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697 articles found

L0190 – Studies on the synthesis of a Mo–30wt%W alloy by non-conventional approaches

In the present study, alternate routes for the synthesis of a single phase Mo–30 wt% W alloy were pursued to surmount the limitations experienced in conventional technique. The process essentially consists of preparation of active Mo and W powders by H2 reduction of the respective oxide intermediates through multiple processing steps and then converting those pure powders into Mo–30 wt% W alloy by mechanical alloying technique (MA) at RT under Ar atmosphere in a high-energy planetary ball mill. The structural evolution of the alloy from the milled powders at different interval of time was studied by X-ray diffraction (XRD) and phase corresponding to Mo–30W alloy was confirmed. The broadening of peaks in XRD pattern was due to crystallite refinement during milling towards the formation of the designated alloy. A high rate of densification for MA powder was achieved during sintering between 900 °C and 1200 °C and density close to theoretical density was attained. The microstructure of sintered alloy exhibited uniform, polyhedral grains with average grain size of about 3 ?m. The morphological evolution of as-milled powder was studied by Scanning electron microscopy (SEM) which revealed the formation of nano sized crystallites with polyhedral shapes. The crystallites were initially arranged in clusters which later on got distributed uniformly with the progress in milling time. The average crystallite size of MA powder was found to be 7.3 nm after 25 h of milling.
S.P. Chakraborty, S. Banerjee, Gopal Sanyal, V.S. Bhave, Bhaskar Paul, I.G. Sharma, A.K. Suri, Journal of Alloys and Compounds 501 (2010) 211–217

L0176 – Feasibility study on utilizing carbon dioxide during the processing of Mg–Al alloys

The feasibility of utilizing carbon dioxide (CO2) during magnesium–aluminium (Mg–Al) alloys processing was investigated by incorporating CO2 gas during melting and casting of the alloys. Mg–Al alloys containing ?3 wt.% and ?5 wt.% Al were processed with and without CO2 atmosphere using the disintegrated melt deposition (DMD) technique. The cast alloys after extrusion were characterized for their structural, physical and mechanical properties to identify the utilization of carbon dioxide during processing. Results indicated that sound, defect-free Mg-Alloys were produced with CO2 processing. Improvement in mechanical properties such as hardness, tensile strength and compressive yield strength were observed. The in situ formation of Al4C3 phase during processing was identified as the reason for the improvement in the properties, which indicated the utilization of carbon dioxide by the melt.
Jayalakshmi Subramanian, Khoo Chee Guan, Joshua Kuma, Manoj Gupta, Journal of Materials Processing Technology 211 (2011) 1416–1422

L0150 – Interfacial investigation of the Co-fired NiCuZn Ferrite/PMN composite prepared by tape casting

The co-firing behavior and interfacial diffusion of the co-fired system of NiCuZn ferrite (abbreviated as NiCuZn) and Pb(Mg1/3Nb2/3)O3 (abbreviated as PMN) relaxor ferroelectric are studied in this work. NiCuZn layers and PMN layers prepared by tape casting were stocked alternately. X-ray diffraction analysis shows no new phase appeared in the mixture of NiCuZn and PMN. Scanning electronic microscopy observation of the bi-layer composite indicates obvious warp at the interface due to the sintering mismatch between ferrite and ferroelectrics. The co-firing property of NiCuZn and PMN is modified by doping appropriate content of Bi2O3. By pressing a mixed composition interlayer in the ratio 50:50 between the ferrite and ferroelectric layers, a crack-free multilayer structure could be obtained.
Chunlin Miao, Ji Zhou, Xuemin Cui, Zhenxing Yue, Longtu Li, J Electroceram (2008) 21, 536–540

L0144 – Non-Newtonian Deformation of Co-Based Metallic Glass at Low Stresses

Abstract—The results of precision measurements of creep in Co-based metallic glass are presented. It is shown that, in spite of generally accepted concepts, plastic flow at low stresses under intense structural relaxation conditions is of a non-Newtonian type. Consequences of this fact are considered
V. Ocelik, Yu. V. Fursova, V. A. Khonik, K. Csach, Physics of the Solid State, Vol. 42, No. 4, 2000, pp. 697–700

L0143 – Mechanisms in oxidation and sintering of magnetite iron ore green pellets

Thermal volume changes and oxidation mechanisms in magnetite iron ore green pellets balled with 0.5% bentonite binder, as a function of raw material fineness and pellet porosity, are shown. When a pellet starts to oxidize, a shell of hematite is formed around the pellet while the core still is magnetite. Dilatation curves were measured under non-oxidizing and oxidizing atmospheres to separately describe thermal volume changes in these two phases. Dilatation measurements showed contraction during oxidation between 330 and 900 °C by 0.5%. The extent of contraction was not influenced by the raw material fineness or the original porosity in pellets. Sintering started earlier in the magnetite phase (950 °C) compared to the hematite phase (1100 °C). The sintering rate increased with increasing fineness in the magnetite concentrate. A finer grind in the raw material would, therefore, promote the formation of duplex structures with a more heavily sintered core pulling away from the less sintered outer shell. At constant porosity in green pellets, the oxidation time became longer as the magnetite concentrate became finer, because of the enhanced sintering. In practical balling, however, the increase in fineness would necessitate the use of more water in balling, which results in an increase in green pellet porosity. These two opposite effects levelled out and the oxidation time became constant when green pellets were balled at constant plasticity. Combining the results from the oxidation and dilatation studies revealed new information on the rate limiting factors in oxidation of iron ore pellets. At 1100 °C, the diffusion rate of oxygen was limited by sintering in the magnetite core, taking place before oxidation rather than by the diffusion rate of oxygen through the oxidized hematite shell, as has been claimed in earlier literature. The oxidation rate was at maximum at around 1100 °C. At 1200 °C, the rate of oxidation substantially decreased because both the hematite shell and the magnetite core show heavy sintering at this temperature. Dilatometer measurements showed large thermal volume changes in the presence of olivine, at temperatures above 1200 °C. This is explained by the dissociation of hematite back to magnetite. Dissociation leads to an increase in the volume of the oxidized shell, while sintering of the magnetite core is further enhanced by the olivine additive.
S.P.E. Forsmo, S.-E. Forsmo, P.-O. Samskog, B.M.T. Björkman, Powder Technology 183 (2008) 247–259

L0132 – Calcined resin microsphere pelletization (CRMP): A novel process for sintered metallic oxide pellets

This study deals with the preliminary development of a powder-free process called calcined resin microsphere pelletization (CRMP) used for the fabrication of metallic oxide pellets. This dustless process could be used for the fabrication of mixed U1?yAmyO2±x pellets dedicated to the transmutation of Am in fast neutron reactors. In this study, porous CeO2 microspheres, used as a surrogate of AmO2, were obtained after ineralization of cerium loaded ion exchange resin beads. These millimetric oxide microspheres were die-pressed into pellets which were then sintered under air to form ceramic pellets. Their densities approached 95% of theoretical density of CeO2 and a homogeneous microstructure was obtained by using optimized microspheres. The influence of calcination parameters on the characteristics of microspheres and on the properties of sintered pellets is discussed.
E. Remy, S. Picart, S. Grandjean, T. Delahaye, N. Herlet, P. Allegri, O. Dugne, R. Podor, N. Clavier, P. Blanchart, A. Ayral, Journal of the European Ceramic Society 32 (2012) 3199–3209

L0131 – Co-sintering and microstructural characterization of steel/cobalt base alloy bimaterials

The objective of this study is to process a bimaterial that combines the mechanical strength of a martensitic steel (X3CrNiMo13-4) and the wear and corrosion resistance of a cobalt base alloy (Stellite 6). The powder metallurgy route includes three steps: co-compaction, debinding, and pressureless co-sintering. The experimental approach consists in studying the compaction, the debinding and the sintering behavior of single materials (dimensional changes during sintering, microstructure, and hardness after sintering) before studying co-sintering. The co-sintering temperature range is defined from thermochemical calculations and single material sintering experiments especially for Stellite 6. Finally, the co-sintering ability is evaluated (green and final densities, shrinkage mismatch, coefficient of thermal expansion…) and the bimaterial sintering is studied. Despite the shrinkage mismatch of single materials, cohesion is achieved between the two materials through the infiltration of the supersolidus liquid from the Co base alloy to the steel and through the formation of an interdiffusion layer between the two materials characterized by a composition gradient.
Céline Pascal, Aurélie Thomazic, Annie Antoni-Zdziobek, Jean-Marc Chaix, J Mater Sci (2012) 47, 1875–1886

L0130 – A Phenomenological Analysis of Sintering Mechanisms of W-Cu from the Effect of Copper Content on Densification Kinetics

The effect of addition of copper on the sintering of a W powder was systematically investigated by the analysis of dilatometric experiments on W and W-Cu compacts prepared with submi- crometric powders. A pure W powder compact and a W-10 wt pct Cu powder compact with the same packing fraction ofWparticles were first studied, in order to analyze the effect of copper at fixed microstructure of the solid W particle packing. A more systematic set of experiments with different copper contents and W particle sizes was also qualitatively analyzed. A phenomeno- logical model of sintering was developed and fitted in order to extrapolate the effect of copper content on sintering kinetics at fixed microstructure of the W particle skeleton. An interpreta- tion of the sintering mechanisms was then proposed. Sintering of a W-Cu powder compact is the result of solid-state sintering of the W skeleton, enhanced by the capillary forces exerted by copper, with the superimposition of a particle rearrangement step after copper melting.
J.-J. Raharijaona, J.-M. Missiaen, D. Bouvard, Metallurgical and Materials Transactions A, Volume 42A, August 2011—2411

L0126 – Dilatometric analysis on shrinkage behavior during nonisothermal sintering of nanocrystalline tungsten mechanically alloyed with molybdenum

The paper attempts to study the shrinkage behavior of nanocrystalline tungsten mechanically alloyed with molybdenum (5, 10, 15 and 20 wt.%). The dilatometric analysis was performed by Setsys Evolution TMA (ambient to 1600 ?C) using constant heating rate (CHR) method. The significant improvement in shrinkage with alloying of molybdenum is attributed to reduced grain size, lowered tungsten carbide contamination and enhanced diffusion kinetics. The initial stage sintering kinetics of W–20Mo alloy has been investigated. The densification starts with Mo diffusion (calculated activation energy = 128 kJ/mol) and proceeds with the diffusion of both along the grain boundaries (calculated activation energy = 307 ± 1 kJ/mol).
Ajeet K. Srivastav, B.S. Murty, Journal of Alloys and Compounds (2012)

L0125 – Sintering kinetics study of mechanically alloyed nanocrystalline Mo- 30 wt % W

The paper details the results of sintering kinetics studies conducted on nanocrystalline Mo- 30 wt % W alloy powders using both conventional sintering method as well as stepwise isothermal dilatometry technique.
Bhaskar Paul, Dheeraj Jain, S.P. Chakraborty, I.G. Sharma, C.G.S. Pillai, A.K. Suri, Thermochimica Acta, 512 (2011) 134-141

L0124 – Sintering kinetics of submicron sized coblat powders

The paper details the results of sintering kinetics studies on submicron sized fine cobalt metal powder prepared through oxalate decomposition route using both conventional sintering method as well as stepwise isothermal dilatometry technique.
Bhaskar Paul, Dheeraj Jain, A.C. Bidaye, I.G. Sharma, C.G.S. Pillai, Thermochimica Acta, 488 (2009) 54-59

L0119 – Thermal cycling behaviour of stir cast Al–Mg alloy reinforced with fly ash

The thermal cycling behaviour of stir cast Al–Mg alloy A535 composites reinforced with various amounts of fly ash was investigated in this study. The test samples were subjected to 10 thermal cycles between 40 and 300 ?C in a Seteram Setsys Evolution Thermomechanical Analyser (TMA). The results show that strain hysteresis loops developed during thermal cycling. The hysteresis and residual plastic strains induced in the alloy during thermal cycling decreased with the addition of fly ash. Also, the incorporation of fly ash in A535 improved its dimensional stability
W.A. Uju, I.N.A. Oguocha, Materials Science and Engineering A 526 (2009) 100–105

L0111 – Effect of milling on the damping behavior of nano-structured copper

In the present study, elemental Cu powder was mechanically milled (MMed) for 10 h to reduce the grain (crystalline) size in the nano-range (<100 nm). The mechanically milled powder (10 h-MMed) and elemental powder without mechanical milling (MM) (0 h-MMed) was consolidated by die-cold compaction and were further hot extruded at different temperatures to maintain a crystallite size within the nano-range. Further, the specimen was tested by a novel free-free type suspended beam arrangement, coupled with circle-fit approach to determine damping characteristics. The characterization results help to understand the effect of the nano-size grains on the overall damping capacity of the bulk samples compared to a normal micro-crystalline sample. Results show that the damping capacity of the nano-grained material increases due to the presence of process induced microstructural changes similar to the damping behavior of a micro-grain sized specimen.
N. Srikanth, M.A. Thein, M. Gupta, Materials Science and Engineering A366 (2004) 38-44

L0106 – The mechanical behavior of magnesium alloy AZ91 reinforced with fine copper particulates

In this study, a hybrid composite based on magnesium alloy AZ91A reinforced with copper particulateswas fabricated using the disintegrated melt deposition (DMD) processing technique followed by hot extrusion. Microstructural characterization of the as-extruded composite sample revealed a near uniform distribution of the copper particulates and other intermetallic phases through the magnesium alloy metal matrix, good integrity at the copper-magnesium alloy matrix interfaces and evidence of minimal porosity. Mechanical property quantification revealed that addition of copper particulates resulted in a significant increase in elastic modulus, 0.2% offset yield strength and ultimate tensile strength of the composite material. However, ductility of the composite was marginally affected when compared to the unreinforced monolithic counterpart. The overall mechanical properties of AZ91A/Cu composite were found to be higher than the silicon carbide particulate reinforced AZ91 composite, even for higher volume fractions of the particulate reinforcement. Influence of copper in the matrix of magnesium alloy AZ91A is examined in light of intrinsic microstructural features and mechanical properties of the composite.
K.F. Ho, M. Gupta, T.S. Srivatsan, Materials Science and Engineering A369 (2004) 302-308

L0105 – Experimental and numerical analysis of the deformation of ferrite segments during sintering

The thermo-mechanical behaviour of hard ferrite powder compacts at high temperature is investigated with a view to simulating dimensional changes occurring during sintering of industrial components. Emphasis is laid on the anisotropy in both shrinkage and viscosity, which is induced by the prior pressing operation performed under magnetic field. Anisotropic shrinkage and viscosity are described according to an original approach based on an orthotropic thermo-elastic equation, which assumes an analogy between the thermal and elastic terms of this equation and the viscous and free sintering deformations. Finite element calculations using this constitutive equation are then carried out on two industrial parts. The comparison between the obtained numerical results and experimental measurements proves the relevance of the proposed model.
F. Toussaint, D. Bouvard, Ph. Tenaud, E. Di Marcello, Journal of Materials Processing Technology 147 (2004) 72-78

L0102 – Increasing elastic modulus, strength and CTE of AZ91 by reinforcing pure magnesium with elemental copper

Heat-treatable AZ91 and 3.9 vol.% copper particulate reinforced magnesium composite was synthesized using an innovative disintegrated melt deposition (DMD) technique followed by hot extrusion. Microstructural characterization of the composite material revealed retention and uniform distribution of reinforcement with defect free interface with the matrix. Physical properties characterization revealed improved dimensional stability of composite when compared to AZ91. Mechanical properties characterization revealed an increase in average values of modulus, 0.2% yield strength and ultimate tensile strength of un-heat-treated composite when compared to T6 heat-treated AZ91 while the ductility was adversely affected. An attempt is made in the present study to compare the microstructural, physical and mechanical properties of Mg/Cup composite with that of the commercially used AZ91 alloy.
S.F. Hassan, K.F. Ho, M. Gupta, Materials Letters 58 (2004) 2143-2146

L0099 – Ductility improvement of Ni-added molybdenum compacts through the addition of Cu and Fe powders

The sintered density of molybdenum can be significantly improved through the addition of a small amount of nickel. However, such addition impairs the ductility due to the formation of a NiMo intermetallic compound at the grain boundaries. This makes the plastic deformation process, such as rolling, drawing, and forging, impossible. This study shows that when copper is added, the sintered density can be further increased, but, not the ductility. This ductility problem of the Mo-Ni-Cu system can be improved when a small amount of iron is added and when the total amount of the alloying Ni, Cu, and Fe is over 6wt%, such as in the Mo-4Ni- 1Cu-1Fe system. Such improvement is attributed to the elimination of the brittle NiMo compounds in the matrix.
K.S. Hwang, H.S. Huang, International Journal of Refractory Metals & Hard Materials 22 (2004) 185-191

L0094 – Microstructural evolution of Y2O3 and MgAl2O4 ODS EUROFER steels during their elaboration by mechanical milling and hot isostatic pressing

Different ODS EUROFER steels reinforced with Y2O3 and MgAl2O4 were elaborated by mechanical milling and hot isostatic pressing. Good compromise between strength and ductility could be obtained but the impact properties remain low (especially for the Y2O3 ODS steel). The materials were structurally characterized at each step of the elaboration. During milling, the martensite laths of the steel are transformed into nano-metric ferritic grains and the Y2O3 oxides dissolve (but not the MgAl2O4 spinels). After the HIP, all the ODS steels remain ferritic with micrometric grains, surrounded by nano-metric grains for the Y2O3 ODS steels. The mechanisms in the Y2O3 ODS steels are complex: the Y2O3 oxides re-precipitate as nano-Y2O3 particles that impede a complete austenitization during the HIP. The quenchability of the ODS steels is modified by the milling process, the oxide nature and the oxide content. Eventually, the advantages and drawbacks of each oxide type are discussed.
C. Cayron, E. Rath, I. Chu, S. Launois, Journal of Nuclear Materials 335 (2004) 83-102

L0093 – Thermal stability and mechanical properties of a Zr-based bulk amorphous alloy

The thermal and mechanical properties of a Zr-Al-Cu-Ti-Ni bulk metallic glass were investigated. The glass transition and the crystallization were studied by calorimetry and X-ray diffraction. It was found that the crystallization occurred in two steps. The precipitating phases, and the activation energies were determined. It was established that the crystallization was controlled by the diffusion of the alloying Cu and Ni atoms. The creep behavior was investigated by indentation tests. The viscosity and the activation energy of the deformation process determined from indentation were in reasonable agreement with those obtained by compression tests.
D. Fatay, J. Gubicza, P. Szommer, J. Lendvai, M. Blétry, P. Guyot, Materials Science and Engineering A 387-389 (2004) 1001-1004

L0092 – Improvements in sintered density and dimensional stability of powder injection-molded 316L compacts by adjusting the alloying compositions

Powder injection molding is a process that provides advantages when making small parts with high density and complicated shapes. However, dimensional control of powder injection-molded stainless steel parts is difficult due to the presence of the liquid phase and the large amount of shrinkage that occurs during sintering. This study examines whether such a problem can be overcome through adjustments in the alloy composition and by making use of Thermo-Calc analysis. The results show that, with an increase in the molybdenum content up to the maximum limit according to existing specifications, a compact can be sintered to high densities without the presence of the liquid phase, while maintaining it in the dual-phase region of gamma + delta. In addition, dimensional control is improved. A slower heating rate is also found to be beneficial. These results are explained through dilatometric analysis and phase diagrams that are calculated using the Thermo-Calc program.
G.J. Shu, K.S. Hwang, Y.T. Pan, Acta Materialia 54 (2006) 1335-1342

L0091 – Studies of Fe-Co based perovskite cathodes with different A-site cations

Iron-cobalt based perovskite cathodes with different A-site cations ((Ln0.6Sr0.4)0.99Fe0.8Co0.2O(3-d), where Ln is La, Pr, Sm or Gd) have been synthesised, characterised by a powder XRD, dilatometry, 4-point DC conductivity measurements, and electrochemical impedance spectroscopy (EIS) on cone shaped electrodes. In addition to this scanning electron microscopy (SEM) was used to characterise the bars. XRD revealed that only the La-containing perovskite was hexagonal. The Pr and Sm perovskites were orthorhombic. The gadolinium-based perovskite was a two phase system consisting of an orthorhombic and a cubic perovskite phase. The thermal expansion coefficient (TEC) increased systematically with a decrease in the size of the A-site cation until the gadolinium-containing perovskite where the TEC decreases abruptly. The total electric conductivity was the highest for the La-based perovskite and the lowest for the Gd-based perovskite as determined by 4-point DC conductivity measurements on bars. A clear correlation between the size of the A-site cation and the electrochemical performance was revealed, as the area specific resistance (ASR) was the lowest for the compounds with the smallest A-site cation. This might be explained on the background of the creation of a two-phase structure with a unique microstructure when the size of the A-site cation is lowered, or that one of the phases has a high electro-catalytic activity towards the electrochemical reduction of oxygen.
K. Kammer, Solid State Ionics 177 (2006) 1047-1051

L0087 – Improving the performance of lead-free solder reinforced with multi-walled carbon nanotubes

In this study, varying weight fractions of multi-walled carbon nanotubes were successfully incorporated into 95.8Sn-3.5Ag-0.7Cu solder, to synthesize novel lead-free composite solders. The composite solders were synthesized via the powder metallurgy route of: blending, compaction, sintering and extrusion. The extruded materials were then characterized for their physical, thermal and mechanical properties. With the addition of increasing weight percentage of carbon nanotubes, the composite solders experienced a corresponding decrease in density values and wetting property improved. The melting temperatures of the composite solders were found to be unchanged with the carbon nanotube additions. Thermomechanical analysis of the composites also showed that the presence of reinforcements decreased the average coefficient of thermal expansion of the solder matrix. An improvement in the mechanical properties was also recorded with the presence of increasing carbon nanotubes. An attempt was made, to correlate the increasing presence of reinforcements with the physical, thermal and mechanical properties obtained.
S.M.L. Nai, J. Wei, M. Gupta, Materials Science and Engineering A 423 (2006) 166-169

L0084 – Development of a novel hybrid aluminum-based composite with enhanced properties

In the present study, a novel aluminum-based hybrid composite containing titanium particulates (discontinuous/particulates reinforcement) and iron mesh (continuous/interconnected reinforcement)was synthesized using a solidification processing route involving disintegrated melt deposition coupled with hot extrusion. Microstructural characterization studies conducted on hybrid composite revealed reduced grain size (~44%) when compared to monolithic aluminum, uniform distribution of unreacted and reacted titanium in matrix, and absence of reaction products at the iron-wire/aluminum matrix interface. Results of properties characterization revealed that the presence of hybrid reinforcement led to a reduction in coefficient of thermal expansion (~7.6%) and an increase in hardness, elastic modulus (~10%), 0.2% yield strength (20%) and ultimate tensile strength (~27%). The enhancement in properties realized in hybrid composite was found to be much higher when compared to conventional Al/SiC composite formulations containing relatively higher weight percentages of SiC particulates.
M. Gupta, M.O. Lai, C.Y.H. Lim, Journal of Materials Processing Technology 176 (2006) 191-199

L0078 – Development of Mg/Cu nanocomposites using microwave assisted rapid sintering

In the present study, magnesium composites containing different amounts of nano-size Cu particulates were successfully synthesized using powder metallurgy (PM) technique incorporating microwave assisted two-directional sintering. The sintered specimens were hot extruded and characterized in terms of physical, microstructural and mechanical properties. Microstructural characterization revealed minimal porosity and the presence of a continuous network of nano-size Cu particulates and Mg2Cu intermetallic phase decorating the particle boundaries of the metal matrix. Coefficient of thermal expansion (CTE) value of magnesium matrix was improved marginally with the addition of nano-size Cu particulates. Mechanical characterization revealed that the addition of nano-size Cu particulates lead to an increase in hardness, elastic modulus, 0.2% yield strength (YS), ultimate tensile strength (UTS) and work of fracture of the matrix. An attempt is made in the present study to correlate the effect of increasing amount of nano-size Cu reinforcement on the microstructure and properties of monolithic magnesium.
W.L.E. Wong, M. Gupta, Composites Science and Technology 67 (2007) 1541-1552

L0072 – Indentation creep behavior of a Zr-based bulk metallic glass

The deformation behavior of a Zr44Ti11Cu10Ni10Be25 bulk metallic glass (LM-1B) was studied in the supercooled liquid region by indentation creep test. Before indentation the glass transition and the crystallization temperatures were determined by calorimeter as 625 and 725 K, respectively. The phases formed during crystallization were identified by X-ray diffraction. The indentation creep experiments were carried out at different temperatures and loads. It was found that the creep can be regarded as Newtonian flow at strain rates between 5x10^(-5) and 5x10^(-4) s-1. The values of the viscosity and the activation energy of deformation were determined in the temperature range of 667-687 K.
D. Fatay, J. Gubicza, J. Lendvai, Journal of Alloys and Compounds 434-435 (2007) 75-78

L0057 – Deformation of steel powder compacts during sintering: Correlation between macroscopic measurement and in situ microtomography analysis

Powder compacts obtained by warm pressing of steel powder containing lubricant were found to swell during a typical delubrication cycle and shrink during sintering. The final dimensional changes of the denser compact were strongly anisotropic. Dilatometry measurements showed that final deformation resulted from microstructure induced by prior die pressing and from various phenomena arising at different stages of the cycle, each of them leading to a specific anisotropic effect. To corroborate this assumption the microstructure evolution of the denser material throughout sintering has been observed using in situ synchrotron X-ray computed microtomography. In addition to visual examination, quantitative analysis of 3D images consisted in searching for a relationship between the morphology and the orientation of pores in 2D sections and measuring local strain with an image correlation technique. From this information a schematic description of the main phenomena responsible for the deformation of steel powder compacts during sintering is proposed.
A. Vagnon, O. Lame, D. Bouvard, M. Di Michiel, D. Bellet, G. Kapelski, Acta Materialia 54 (2006) 513-522

L0043 – Stress relaxation of bulk and ribbon glassy Pd40Cu30Ni10P20

Detailed measurements of linear heating and isothermal stress relaxation of bulk and ribbon glassy Pd40Cu30Ni10P20 below the glass transition temperature have been performed. Using the activation energy spectrum reconstructed from these measurements, the temperature dependence of the shear viscosity has been calculated. It has been found that this dependence agrees with that derived directly from the creep measurements. This provides strong support for understanding the stress relaxation as a result of the stress-oriented irreversible structural relaxation with distributed activation energies.
O.P. Bobrov, K. Csach, V.A. Khonik, K. Kitagawa, S.N. Laptev, M.Yu. Yazvitsky, Scripta Materialia 54 (2006) 369-373

G0014 – Technological plasticity studies of the FeAl intermetallic phase-based alloy

Results of hot torsion tests of the Fe-40Al-5Cr-0.2Mo-0.2Zr-0.02B alloy are presented in the paper. The alloy was obtained by melting in an induction furnace. The tests were carried out using a plastometer of the Sataram type in the temperature range of 1123-1273 K and strain rates of 0.06, 0.24, 0.48 and 2.42 s-1 that were close to those used in plastic working processes. In the alloy studied the super-plasticity phenomenon was observed. The shape of the flow curves indicated that dynamic recrystallisation occurred during the super-plastic deformation. This was confirmed by studies of the alloy structure. Also traces of dynamic recovery were observed. The value of the activation energy Q=343 kJ/mol for dynamical recrystallisation is close to the activation energy of aluminium diffusion in the FeAl phase. The results have revealed that cast FeAl-based alloy can be process by superplasic forming in the range 1123-1223 K at strain rates about 1 s-1.
M. Kupka, Intermetallics 12 (2004) 295-302

G0011 – High-temperature thermogravimetric analysis. Influence of gas pressure on kinetics of reactions in the solid state

A magnetic balance apparatus has been set up to follow reactions in the solid state under controlled conditions of pressure and temperature (25-1000°) Magnetic properties are characteristic of solid structures, and thermomagnetic analysis (T. M. A.) can give the variations of the sample susceptibility during the course of a reaction (susceptibilities of the new phases and of initial compounds not yet transformed). By continuous measurement of this susceptibility with the Faraday method, the conversion degree of the synthesis can be obtained. T. M. A. has been used to study the influence of a gas on a solid-solid reaction in which no gas can be evolved or consumed. An example is given for iron tungstate synthesis: Fe203(s) + WO3(s) --> Fe2WO6(s). At 800° the reaction kinetics depends on the nature and the pressure of the gas.
G. Thomas and F. Ropital, Journal of Thermal Analysis 30 (1985) 121-128

E0343 – Investigation of hot cracking resistance of 2205 duplex steel

Austenitic duplex steel of the brand 2205 according to Avesta Sheffield is used for welded constructions (pipelines, tanks) in the petrol industry, chemical industry and food industry. It is important to know the range of high-temperature brittleness in designing welding technology for constructions made of this steel type. There is no data in literature concerning this issue. High-temperature brittleness tests using the simulator of heat flow device Gleeble 3800 were performed. The tests results allowed the evaluation of the characteristic temperatures in the brittleness temperature range during the joining of duplex steels, specifically the nil-strength temperature (NST) and nil-ductility temperatures (NDT) during heating, the strength and ductility recovery temperatures (DRT) during cooling, the Rfparameter (Rf = (Tliquidus – NDT)/NDT) describing the duplex steel inclination for hot cracking, and the brittleness temperature range (BTR). It has been stated that, for the examined steel, this range is wide and amounts to ca. 90 °C. The joining of duplex steels with the help of welding techniques creates a significant risk of hot cracks. After analysis of the DTA curves a liquidus temperature of TL = 1465 °C and a solidus temperature of TS = 1454 °C were observed. For NST a mean value was assumed, in which the cracks appeared for six samples; the temperature was 1381 °C. As the value of the NDT temperature 1367 °C was applied while for DRT the assumed temperature was 1375 °C. The microstructure of the fractures was observed using a Hitachi S-3400N scanning electron microscope (SEM). The analyses of the chemical composition were performed using an energy-dispersive X-ray spectrometer (EDS), Noran System Six of Thermo Fisher Scientific. Essential differences of fracture morphology type over the brittle temperature range were observed and described.
J Adamiec, B ?cibisz, IOP Conf. Series: Materials Science and Engineering 7 (2010) 012001

E0342 – Experimental study of the Fe–Ni–Ti system

In this investigation phase relations in the Fe–Ni–Ti system were studied and two isothermal sections at 800 °C and 1000 °C as well as a revised liquidus projection were established. Microstructural characterisation of the as-cast alloys and of samples equilibrated at 800 and 1000 °C was performed by scanning electron microscopy (SEM), chemical compositions of the phases were analysed by electron probe microanalysis (EPMA), and liquidus temperatures were examined by differential thermal analysis (DTA). The experimental results clarify some uncertainties concerning the melting behaviour and the solid-state phase equilibria between the phases (Ni,Fe)Ti2, (Fe,Ni)Ti and ?-Ti. The present data also confirm that the solid solubility of Ti in ?-(Fe,Ni) varies in dependence on the Fe:Ni ratio and decreases with decreasing temperature. The liquidus projection as well as the reaction scheme in the Ti-lean part are modified because two ternaries eutectic E1: L ? ?-(Fe,Ni) + Fe2Ti + Ni3Ti and E2: L ? Fe2Ti + Ni3Ti + (Fe,Ni)Ti are found at 1108 and 1099 °C, respectively.
L.I. Duarte, U.E. Klotz, C. Leinenbach, M. Palm, F. Stein, J.F. Löffler, Intermetallics 18 (2010) 374–384

E0341 – Cu-based metallic glass particle additions to significantly improve overall compressive properties of an Al alloy

We report the development of a novel light-weight Al (520) alloy-based composite reinforced with particles of a Cu-based (Cu54Zr36Ti10) metallic glass by mechanical milling followed by induction heated sintering. The consolidation of the composite is performed at a temperature in the super-cooled liquid region of the metallic glass just above its glass-transition temperature (Tg). Metallic glasses are a promising alternative reinforcement material for metal-matrix composites capable of producing significant strengthening along with a «friendly» sintering behavior. The mechanical milling procedures were properly established to allow reduction of the size of the metallic glass particles and their uniform distribution in the matrix. Microstructural observation of the composite did not reveal any porosity. The interface between the glassy particles and the matrix remained free of such defects. The fully dense consolidated composite showed a drastic gain in specific yield strength under compression relative to the matrix alloy and appreciable plasticity at fracture.
D.V. Dudina, K. Georgarakis, M. Aljerf, Y. Li, M. Braccini, A.R. Yavari, A. Inoue, Composites: Part A 41 (2010) 1551–1557

E0330 – Influence of the morphologic evolution of the eutectic carbides at high temperature on the thermal expansion behavior of refractory cast alloys

Two alloys particularly rich in carbides, a nickel-based one reinforced by chromium carbides and a cobalt-based one strengthened by tantalum carbides were characterized by metallography and their hardness and thermal expansion behavior tested, after alloys had undergone a more or less long aging treatment at high temperature. Aging induces a progressive coarsening and/or fragmentation of these interdendritic carbides, with as first consequence a decrease in hardness. Also due to these morphology changes, aging the alloys on long time leads to a loss of effect of the carbides on the thermal expansion behavior of the alloys. The total thermal expansion, initially lowered by the rigid carbides network, is then free again. Indeed, the high temperature phenomenon of plastic or viscous-plastic deformation in compression of the matrix by the initial continuous carbides network has almost disappeared.
Patrice Berthod, Cédric Heil, Lionel Aranda, Journal of Alloys and Compounds 504 (2010) 243–250

E0329 – The ternary Cr–Al–Nb phase diagram: Experimental investigations of isothermal sections at 1150, 1300 and 1450 ?C

Isothermal sections of the ternary Cr–Al–Nb phase diagram were experimentally investigated for temperatures of 1150, 1300, and 1450 °C by electron-probe microanalysis (EPMA), X-ray diffraction (XRD), differential thermal analysis (DTA) and light-optical (LOM) as well as scanning electron microscopy (SEM). Cr–Al–Nb alloys were prepared by levitation melting and annealed at temperatures between 1150 and 1450 °C for up to 1500 h. The most striking feature of the ternary Cr–Al–Nb phase diagram is the extended phase field of the cubic C15 and the hexagonal C14 Laves phase Nb(Cr,Al)2. With increasing Al content, the Laves phase polytype changes from C15 to C14. Both phase fields are separated by a small two-phase field, which shifts to lower Al contents with increasing temperature. The lattice parameters of both Laves phase polytypes and of all other phases occurring in this system were studied in dependence on composition and the solubilities of ternary elements in the binary phases were established.
O. Prymak, F. Stein, Journal of Alloys and Compounds 513 (2012) 378– 386

E0328 – Experimental determination and thermodynamic modeling of the Ni–Re binary system

The phase diagram of the Ni–Re binary system has been partially reinvestigated by chemical, structural and thermal characterization of the arc melted alloys. The experimental results obtained during the present investigation were combined with the literature data and a new phase diagram of the Ni–Re binary system is proposed. In comparison with the Ni–Re phase diagram proposed by Nash et al. in 1985 [1], significant differences in the homogeneity domains, freezing ranges and peritectic reaction temperature were evidenced. On the other hand, thermodynamic modeling of the studied system by using the new experimental information has also been carried out with the help of the CALPHAD method. The calculated Ni–Re phase diagram showed a good agreement with the selected experimental information.
Khurram Yaqoob,Jean-Marc Joubert, Journal of Solid State Chemistry 196 (2012) 320–325

E0318 – Parametric optimization of Ti–Ni powder mixtures produced by mechanical alloying

In this study, a set of Ti–50 at.% Ni elemental powder mixtures were processed through mechanical alloying (MA). The objectives were to induce during MA the formation of a lamellar microstructure and to apply a design of experiments, based on the Taguchi method, to optimize the MA parameters. Enthalpy measurements associated to the high temperature reaction between Ni and Ti powders were used to evaluate the effect of the MA parameters. It is known that different ball-impact energies lead to different reaction pathways. The results indicate that milling time affects significantly (74% contribution) the enthalpy of the high temperature reaction while the milling speed has a lower effect (25% contribution). Moreover, whatever the milling conditions, the powder was a mixture of both crystalline phases and an amorphous phase. Their microstructure was composed of a multilayer of alternating Ni and Ti that in some cases was constituted by nanolayers. The oxygen and nitrogen contents of the milled powders ranged between 0.29 and 0.79 wt%, and 0.15 and 0.90 wt%, respectively.
F. Neves, F.M. Braz Fernandes, I. Martins, J.B. Correia, Journal of Alloys and Compounds 509S (2011) S271–S274

E0313 – Experimental investigation of the Cu-Si phase diagram at x(Cu)>0.72

Cu–Si phase equilibria have been investigated at compositions greater than 72 at.% Cu by X-ray diffraction, optical and electronic microscopy, electron probe microanalysis and differential thermal analysis. The general aspects of the phase equilibria already reported in literature have been substantially confirmed, but selected composition ranges and the nature of a few invariant equilibria have been modified. In particular stability ranges of the ?, ? and ? phases have been slightly modified as well as temperature and nature of the invariant equilibria related to the ? ? ? transformation. Stability of the ?-(Cu15Si4) phase has been especially investigated concluding that it is thermodynamically stable but kinetically inhibited by nucleation difficulties which become especially effective when samples are synthesized in very high purity conditions. Crystal structure and composition ranges of the high temperature ? and ? phases, despite difficulties by the non-quenchability of these phases, have been investigated by different methods including high temperature XRD.
Katarzyna Sufryd, Norbert Ponweiser, Paola Riani, Klaus W. Richter, Gabriele Cacciamani, Intermetallics 19 (2011) 1479-1488

E0312 – Microstructures and mechanical properties of Fe-Al-Ta alloys with strengthening Laves phase

The addition of Ta to Fe–Al alloys results in the formation of a stable Ta(Fe,Al)2 Laves phase with hexagonal C14 structure in the Fe–Al phase at temperatures of 800, 1000 and 1150 °C. It was found that the solubility of Ta in Fe–Al is generally low and the solubility of Ta varies with Al content. Respective isothermal sections of the Fe–Al–Ta system have been established. Particular attention has been given to precipitation in the Fe3Al phase with a small addition of Ta. At intermediate temperatures, 600–750 °C, an additional Heusler-type phase with L21-structure precipitates, which transforms at longer times and high temperatures to the stable C14 Laves phase. The yield stress in compression and the creep behaviour of the Fe–Al–Ta alloys with various microstructures were studied. Due to the presence of the L21-Heusler phase, the yield stress and the creep resistance at temperatures below 700 °C was increased considerably
D.D. Risanti, G. Sauthoff, Intermetallics 19 (2011) 1727-1736

E0311 – Phase equilibria in the Al-Mo-Si system

The ternary Al–Mo–Si phase diagram was investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA), electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). Ternary phase equilibria were investigated within two isothermal sections at 600 °C for the Mo-poor part and 1400 °C for the Mo-rich part of the phase diagram. The solubility ranges of several phases including MoSi2 (C11b) as well as Mo(Si,Al)2 with C40 and C54 structure were determined. The binary high temperature phase Al4Mo was found to be stabilized at 600 °C by addition of Si. DTA was used to identify 9 invariant reactions and thus constructing a ternary reaction scheme (Scheil diagram) in the whole composition range. A liquidus surface projection was constructed on basis of the reaction scheme in combination with data for primary crystallization from as-cast samples determined by SEM measurements.
Norbert Ponweiser, Werner Paschinger, Anna Ritscher, Julius C. Schuster, Klaus W. Richter, Intermetallics 19 (2011) 409-418

E0310 – Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase ?1-Al(1 ?)Cu

The phase equilibria and reaction temperatures in the system Al–Cu were re-investigated by a combination of optical microscopy, powder X-ray diffraction (XRD) at ambient and elevated temperature, differential thermal analysis (DTA) and scanning electron microscopy (SEM). A full description of the phase diagram is given. The phase equilibria and invariant reactions in the Cu-poor part of the phase diagram could be confirmed. The Cu-rich part shows some differences in phase equilibria and invariant reactions compared to the known phase diagram. A two phase field was found between the high temperature phase ?1 and the low temperature phase ?2 thus indicating a first order transition. In the ?1/?2 region of the phase diagram recent findings on the thermal stability could be widely confirmed. Contrary to previous results, the two phase field between ? and ?1 is very narrow. The results of the current work indicate the absence of the high temperature ?0 phase as well as the absence of a two phase field between ?1 and ?0 suggesting a higher order transition between ?1 and ?0. The structure of ?0 (I-43m, Cu5Zn8-type) was confirmed by means of high-temperature XRD. Powder XRD was also used to determine the structure of the high temperature phase ?1-Al1??Cu. The phase is orthorhombic (space group Cmmm) and the lattice parameters are a = 4.1450(1) Å, b = 12.3004(4) Å and c = 8.720(1) Å; atomic coordinates are given.
Norbert Ponweiser, Christian L. Lengauer, Klaus W. Richter, Intermetallics 19 (2011) 1737-1746

E0308 – Constitutional and microstructural investigation of the pseudobinary NiAl-W system

Pseudobinary NiAl–W section in the range 0.7–1.8 at% was characterised regarding solidification microstructure and constitution. The existence of eutectic reaction was confirmed and occurs at temperature of 1664 ± 2 °C and the composition of 1.5 at% W. As-cast microstructures indicated that the NiAl–W system is an anomalous eutectic with skewed coupled zone and that the NiAl phase is a preferential phase for eutectic nucleation. Directionally solidified alloy containing 1.5 at% W exhibited entirely eutectic structure characterised by eutectic cells with the average value of 500 ?m, interfibre spacing 3.5 ?m, fibre diameter 300 nm, and volume fraction of the W phase 1.4%. The solubility of W in the intermetallic phase is <0.04 at% and the solubility of Ni and Al in the W phase is negligible. Crystallographic orientation between the constituent phases was established to be cube on cube. Based on the results obtained by DTA, microstructural and compositional analysis, a new isoplethal section NiAl–W of the ternary Al–Ni–W system has been proposed.
Srdjan Milenkovic, André Schneider, Georg Frommeyer, Intermetallics 19 (2011) 342-349

E0307 – Phase equilibria in the AleSieV system: The vanadium rich part

The V-rich part of the Al–Si–V phase diagram was determined by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Phase equilibria were investigated at two isothermal sections at 850 and 1300 °C. High temperature DTA was performed to identify the ternary invariant reactions yielding a ternary reaction scheme and the vertical section at 50 at.% V. As cast samples were investigated in order to gain additional information about primary crystallization fields. A liquidus surface projection was constructed for the entire ternary system by combining our experimental data with those from literature.
Beatrix Huber, Klaus W. Richter, Intermetallics 19 (2011) 369-375

E0304 – Carburization of W- and Re-rich Ni-based alloys in impure helium at 1000 C

The surface and microstructure stability of experimental W- and Re-rich Ni-based alloys in an impure-helium environment containing only CO and CO2 as impurities (ppm level) have been investigated at 1000 °C. All the alloys carburized during 50 h of exposure, and, depending on the alloy composition, different carbides of the type M6C, M7C3 and M23C6 formed on the alloy surface, in grain interiors and at grain boundaries. Microprobe analysis and Calphad-based calculations indicated that the chromium carbides (particularly Cr23C6) were enriched by rhenium. Extended exposure (225 h) led to the disappearance of surface transient carbides and the growth of surface oxide Cr2O3 occurred.
Raghavendra R. Adharapurapu, Deepak Kumar, Jun Zhu, Tresa M. Pollock, Corrosion Science 53 (2011) 388–398

E0302 – Is Tl2Ni3S2 a mixed valent compound? Crystal and electronic structure investigations

The crystal and electronic structure of Tl2Ni3S2 is investigated by X-ray structure determination and DFT calculations. The question of charges and possible mixed valences of two different Tl positions in Tl2Ni3S2 is discussed with respect to crystal and electronic structure arguments. Crystal structure parameters were redetermined from single crystal data. A relation is given to typical Tl states in reference compounds like mixed valent Tl2S2, high-pressure TlS, LiTl, and ThCr2Si2 type TlNi2S2. This allows for a comparison of different Tl sites with respect to atomic distances, coordinations, valence, charge, and bonding as well as charge redistribution within layered Ni–S substructures. Complementary methods of charge determination from theory are applied as orbital analysis from precise full potential calculations and charge density analysis by zero flux surface integration according to the AIM theory.
F. Bachhuber, I. Anusca, J. Rothballer, F. Pielnhofer, P. Peter, R. Weihrich, Solid State Sciences 13 (2011) 337-343

E0300 – Self-flux growth of large EuCu2Si2 single crystals

Large single crystals of the EuCu2Si2 intermetallic compound have been successfully grown by a high pressure vertical floating zone method with optical heating. The suppression of evaporation of volatile elements and control of the floating zone temperature are the key factors for the stability of the growth process. A low travelling velocity of 3 mm/h and a short length of the floating zone play an important role in phase selection and formation of a EuCu2Si2 single crystal. Measurements of oriented single crystalline EuCu2Si2 samples reveal a non-linear temperature dependence of the magnetic susceptibility attributed to the valence fluctuations in Eu ion. But no magnetic ordering transition occurs at T>2 K. The magnetic susceptibility data display significant anisotropy with a magnetic easy c-axis ([0 0 1]). In contrast to the magnetic susceptibility, the anisotropy in the electrical resistivity for the two different crystallographic orientations is less significant.
Chongde Cao, Wolfgang Löser, Günter Behr, Rüdiger Klingeler, Norman Leps, Hartmut Vinzelberg, Bernd Büchner, Journal ofCrystal Growth 318(2011)1043–1047

E0299 – New types of lead-free solders on the base of tin and their properties

The aim of the work is an experimental study of binary, ternary and quaternary systems on the base of tin alloys. 22 alloys with different ratios of individual elements Ag, Cu, In, Sb, Bi, and Sn were prepared experimentally. In addition, 6 alloys of lead-free solders produced commercially (Kovohut? P?íbram nástupnická, a.s.) were used and the Pb-Sn solder served as a comparative etalon. The following characteristics were studied: temperatures and enthalpies of phase transformations (DTA, TG, DSC) of individual solders at the rates of re-heating and cooling of specimens of about 4?Cmin?1, microstructural analysis (optical metallography) and microhardness of specimens, chemical analysis, microanalysis of individual phases in the structure of solders (WDX, EDX), measurement of surface tension and density of solders in dependence on the temperature, test of wettability with or without use of fluxes, measurement of corrosion properties, measurement of electrical resistivity
J. Drápala, R. Kozelková, R. Burkovi?, B. Smetana, R. Dudek, S. Lasek, J. Urbánek, K. Dušek, M. Hájek, Kovove Mater. 47, 2009, 283–293

E0281 – Isothermal section of the Er–Cu–Ga ternary system at 973 K

Phase relations in the Er–Cu–Ga ternary system have been established at 973 K by means of powder X-ray diffraction complemented by energy dispersive spectroscopy coupled to scanning electron microscopy. The isothermal section of the phase diagram comprises eight extensions of binaries into the ternary system, ErCu1?xGax (x ? 0.5), ErCu2?xGax (x ? 1.1), ErCu5?xGax (x ? 0.5), Er5CuxGa3?x (x ? 0.60), Er3CuxGa2?x (x ? 0.24), ErCuxGa1?x (x ? 0.10), ErCuxGa2?x (x ? 0.30) and ErCuxGa3?x (x ? 0.35), as well as six ternary intermediate phases, ErCuxGa2?x (0.4 ? x ? 0.7), Er14Cu51?xGax (5.5 ? x ? 11.0), ErCu5?xGax (0.8 ? x ? 2.3), Er2Cu17?xGax (4.9 ? x ? 8.0), ErCu12?xGax (5.7 ? x ? 6.7) and Er3CuxGa11?x (1.5 ? x ? 4.4), all deriving from binary structure-types.
B. Belgacem, M. Pasturel, O. Tougait, S. Nouri, H. El Bekkachi, I. Péron, R. Ben Hassen, H. Noël, Journal of Alloys and Compounds 531 (2012) 41– 45

E0280 – Thermal studies for preparation of Nb10Hf1Ti Alloy

The aim of this work is to evaluate the feasibility of preparation of Nb10Hf1Ti alloy by magnesiothermic reduction of its oxides. DTA studies were conducted to identify the reduction temperature for coreduction of the mixed oxides of Nb2O5, HfO2, and TiO2 by magnesium under reducing atmosphere. Based on DTA analysis, experiments were carried out to prepare Nb10Hf1Ti alloy by magnesiothermic reduction of their oxides at 750 °C. The reduced product was analyzed for its phases by X-ray diffraction. The excess Mg was leached out, the alloy mixture was vacuum dried, pelletized, sintered, and electron beam melted to get a consolidated alloy of the required composition. The alloy was characterized using different techniques such as optical microscopy, scanning electron microscopy, and chemical analysis. Microstructural observations revealed the formation of coarse grain structure in the consolidated alloy. The alloy product was also evaluated for its micro hardness.
Pamela Alex, Jugal Kishor, I. G. Sharma, J Therm Anal Calorim, 2012

E0278 – Phase transition temperatures of Sn–Zn–Al system and their comparison with calculated phase diagrams

The Sn–Zn–Al system was studied in connection with the possible substitution of lead-based solders for temperatures up to 350 °C. Ternary alloys with up to 3 wt% of aluminium were prepared. The investigated alloys lie close to the monovariant line (eutectic valley) of the Sn–Zn–Al system. The temperatures of phase transitions of six binary Sn–Zn reference alloys and fourteen ternary Sn–Zn–Al alloys using DTA method were investigated in this paper. DTA experiments were performed at the heating/cooling rate of 4 °C min-1 using Setaram SETSYS 18TM experimental equipment. The temperatures of phase transitions in the ternary Sn–Zn–Al system were obtained, namely, the temperature of ternary eutectic reaction TE1 (197.7 ± 0.7 °C), temperature of ternary transition reaction TU1 (278.6 ± 0.7 °C), temperatures of liquidus and other transition temperatures for studied alloys. Temperatures obtained during DTA heating runs were used as authoritative. DTA curves obtained during cooling enabled realising better differentiation of the obtained overlapped heat effects (peaks) during heating. Theoretical isopleths of the Sn–Zn–Al phase diagram were calculated using the Thermocalc software and MP0602 thermodynamic database. Experimental data were compared with the calculated temperatures, and a good agreement was obtained.
Bedrich Smetana, Simona Zla, Ales Kroupa, Monika Zaludova, Jarom?r Drapala, Rostislav Burkovic, Daniel Petlak, J Therm Anal Calorim (2012) 110:369–378

E0277 – Experimental study of Fe–C–O based system below 1000 °C

The paper deals with the study of phase transformation temperatures of Fe (Fe–C–O) basedmetallic alloys. Six model alloyswith graded carbon and oxygen contentwere used for experimental investigation. Low-temperature region (<1000 °C) was the investigated area. Phase transformation temperatureswere obtained using Differential thermal analysis and Setaram Setsys 18TM laboratory system. Controlled heating was conducted at the rates of 2, 4, 7, 10, 15, 20 °C min-1. Region of eutectoid transformation (Fe?(C) + Fe3C ? Fe?(C)), alpha–gamma (Fe?(C) ? Fe?(C)) and transformation Fe?(O) + Fe0.92O ? Fe?(O) + Fe0.92O was studied. New original data (phase transformation temperatures) were obtained in this study. The relationship between shift of phase transformation temperatures and chemical composition (mainly carbon and oxygen content) is investigated in this paper. To achieve good approximation to the equilibrium conditions, the extrapolation of the obtained phase transformation temperatures to the zero heating rate was performed. The influence of experimental conditions (heating rate) on temperatures of phase transformations was studied as well. Comparison of the obtained experimental data with the data presented in the accessible literature and IDS calculations (Solidification Analysis Package)was carried out. It follows fromliterature search that there is a lack of thermo-physical and thermo-dynamical data on Fe–C–O system.
Monika Zaludova, Bedrich Smetana, Simona Zla, Jana Dobrovska, Vlastimil Vodarek, Katerina Konecna, Vlastimil Matejka, Petra Matejkova, J Therm Anal Calorim, 2012

E0275 – Determination of thermophysical properties of high temperature alloy IN713LC by thermal analysis

The presented paper deals with the study of thermophysical properties of cast and complex alloyed nickel based on superalloy Inconel 713LC (IN713LC). In this work, the technique of Differential Thermal Analysis was selected for determination of the phase transformation temperatures and for the study of the effect of varying heating/cooling rate at these temperatures. The samples taken from as-received state of superalloy were analysed at heating and cooling rates of 1, 5, 10, 20 and 50°C min-1 with the help of the experimental system Setaram SETSYS 18TM. Moreover, the transformation temperatures at zero heating/cooling rate were calculated. The recommended values for IN713LC after correcting to a zero heating rate, are 1205°C (Tc0,solvus), 1250°C (solidus) and 1349°C (liquidus). Influence of heating/cooling rate on shift of almost all temperatures of phase transformations was established from the DTA curves. Undercooling was observed at the cooling process. T
Simona Zla, Bedrich Smetana, Monika Zaludova, Jana Dobrovska, Vlastimil Vodarek, Katerina Konecna, Vlastimil Matejka, Hana Francova, J Therm Anal Calorim, 2012

E0274 – Experimental study of Fe–C–O based system below 1000°C

The paper deals with the study of phase transformation temperatures of Fe (Fe–C–O) based metallic alloys. Six model alloys with graded carbon and oxygen content were used for experimental investigation. Low-temperature region (1000°C) was the investigated area. Phase transformation temperatures were obtained using Differential thermal analysis and Setaram Setsys 18TM laboratory system. Controlled heating was conducted at the rates of 2, 4, 7, 10, 15, 20°Cmin-1. Region of eutectoid transformation (Fe?(C) + Fe3C ? Fe?(C)), alpha–gamma (Fe?(C) ? Fe?(C)) and transformation Fe?(O) + Fe0.92O ? Fec(O) + Fe0.92O was studied. New original data (phase transformation temperatures) were obtained in this study. The relationship between shift of phase transformation temperatures and chemical composition (mainly carbon and oxygen content) is investigated in this paper. To achieve good approximation to the equilibrium conditions, the extrapolation of the obtained phase transformation temperatures to the zero heating rate was performed. The influence of experimental conditions (heating rate) on temperatures of phase transformations was studied as well. Comparison of the obtained experimental data with the data presented in the accessible literature and IDS calculations (Solidification Analysis Package) was carried out. It follows from literature search that there is a lack of thermo-physical and thermo-dynamical data on Fe–C–O system.
Monika Zaludova, Bedrich Smetana, Simona Zla, Jana Dobrovska, Vlastimil Vodarek, Katerina Konecna, Vlastimil Matejka, Petra Matejkov, J Therm Anal Calorim, 2012

E0273 – Phase transition temperatures of Sn–Zn–Al system and their comparison with calculated phase diagrams

The Sn–Zn–Al system was studied in connection with the possible substitution of lead-based solders for temperatures up to 350 C. Ternary alloys with up to 3 wt% of aluminium were prepared. The investigated alloys lie close to the monovariant line (eutectic valley) of the Sn–Zn–Al system. The temperatures of phase transitions of six binary Sn–Zn reference alloys and fourteen ternary Sn–Zn–Al alloys using DTA method were investigated in this paper. DTA experiments were performed at the heating/cooling rate of 4 C min-1 using Setaram SETSYS 18TM experimental equipment. The temperatures of phase transitions in the ternary Sn–Zn–Al system were obtained, namely, the temperature of ternary eutectic reaction TE1 (197.7 ± 0.7 C), temperature of ternary transition reaction TU1 (278.6 ± 0.7 C), temperatures of liquidus and other transition temperatures for studied alloys. Temperatures obtained during DTA heating runs were used as authoritative. DTA curves obtained during cooling enabled realising better differentiation of the obtained overlapped heat effects (peaks) during heating. Theoretical isopleths of the Sn–Zn–Al phase diagram were calculated using the Thermocalc software and MP0602 thermodynamic database. Experimental data were compared with the calculated temperatures, and a good agreement was obtained.
Bedrich Smetana, Simona Zla, Ales Kroupa, Monika Zaludova, Jarom?r Drapala, Rostislav Burkovic, Daniel Petlak, J Therm Anal Calorim, 2012

E0271 – Stabilization of Thermosolutal Convective Instabilities in Ni-Based Single-Crystal Superalloys: Carbon Additions and Freckle Formation

The effect of carbon additions on the solidification characteristics of single-crystal Ni-based superalloys has been studied over a range of composition with large variations in Re, W, and Ta. Under constant processing conditions, nominally similar experimental alloys containing additions of 0.1 wt pct C exhibited a decreased tendency to develop grain defects, such as freckle chains. The carbon additions resulted in the formation of Ta-rich MC carbides with three distinct morphologies: blocky, nodular, and script. These carbides all precipitate near the liquidus temperature of the alloy. Intentional carbon additions also affected the segregation behavior of the constituent elements. Comparison of experimentally measured distribution coefficients assessed via application of a Scheil-type analysis revealed reduced segregation of Re,W, and Ta in experimental single-crystal alloys containing carbon. The mechanisms by which carbon additions influence freckle formation are considered.
S. Tin, T.M. Pollock, W. Murphy, Metallurgical and Materials Transactions A, 32A, July 2001, 1743

E0269 – Reaction Sequences in the Formation of Silico-Ferrites of Calcium and Aluminum in Iron Ore Sinter

Complex silico-ferrites of calcium and aluminium (low-Fe form, denoted as SFCA; and high-Fe, low-Si form, denoted as SFCA-I) constitute up to 50 vol pct of the mineral composition of fluxed iron ore sinter. The reaction sequences involved in the formation of these two phases have been determined using an in-situ X-ray diffraction (XRD) technique. Experiments were carried out under partial vacuum over the temperature range of T = 22°C to 1215°C (alumina-free compositions) and T = 22°C to 1260°C (compositions containing 1 and 5 wt pct Al2O3) using synthetic mixtures of hematite (Fe2O3), calcite (CaCO3), quartz (SiO2), and gibbsite (Al(OH)3). The formation of SFCA and SFCA-I is dominated by solid-state reactions, mainly in the system CaO-Fe2O3. Initially, hematite reacts with lime (CaO) at low temperatures (T ~ 750 °C to 780 °C) to form the calcium ferrite phase 2CaO.Fe2O3 (C2F). The C2F phase then reacts with hematite to produce CaO.Fe2O3 (CF). The breakdown temperature of C2F to produce the higher-Fe2O3 CF ferrite increases proportionately with the amount of alumina in the bulk sample. Quartz does not react with CaO and hematite, remaining essentially inert until SFCA and SFCA-I began to form at around T = 1050 °C. In contrast to previous studies of SFCA formation, the current results show that both SFCA types form initially via a low-temperature solid-state reaction mechanism. The presence of alumina increases the stability range of both SFCA phase types, lowering the temperature at which they begin to form. Crystallization proceeds more rapidly after the calcium ferrites have melted at temperatures close to T = 1200 °C and is also faster in the higher-alumina-containing systems.
Nicola V.Y. Scarlett, Mark I. Pownceby, Ian C. Madsen, Axel N. Christensen, Metallurgical and Materials Transactions B, 35B, October 2004, 929

E0265 – A new experimental phase diagram investigation of Cu–Sb

The binary system Cu–Sb is a constituent system that is studied in investigations of technically important ternary and quaternary alloy systems (e.g., casting alloys and lead-free solders). Although this binary system has been thoroughly investigated over the last century, there are still some uncertainties regarding its high-temperature phases. Thus, parts of its phase diagram have been drawn with dashed lines in reviews published in the literature. The aim of this work was to resolve these uncertainties in the current phase diagram of Cu–Sb by performing XRD, SEM-EDX, EPMA, and DTA. The results from thermal analysis agreed well with those given in the literature, although some modifications due to the invariant reaction temperatures were necessary. In particular, reactions located on the Cu-rich side of the nonquenchable high-temperature b phase (BiF3-type) left considerable scope for interpretation. Generally, the structural descriptions of the various binary phases given in the literature were verified. The range of homogeneity of the e phase (Cu3Ti type) was found to be higher on the Sb-rich side. Most of the reaction temperatures were verified, but a few had to be revised, such as the eutectoid reaction ? ? ? + ? at 440 °C (found to occur at 427 °C in this work) and the eutectoid reaction ? ? (Cu) + ? at 400 °C (found to occur at 440 °C in this work). Further phase transformations that had previously only been estimated were confirmed, and their characteristic temperatures were determined.
Siegfried Fürtauer, Hans Flandorfer, Monatsh Chem (2012) 143, 1275–1287

E0263 – Microsegregation and Secondary Phase Formation During Directional Solidification of the Single-Crystal Ni-Based Superalloy LEK94

A multicomponent phase-field method coupled to thermodynamic calculations according to the CALPHAD method was used to simulate microstructural evolution during directional solidification of the LEK94 commercial single-crystal Ni-based superalloy using a two-dimensional unit cell approximation. We demonstrate quantitative agreement of calculated microsegregation profiles and profiles determined from casting experiments as well as calculated fraction solid curves with those determined in differential thermal analysis (DTA) measurements. Finally, the role of solidification rate on dendrite morphology and precipitation of the secondary phases is investigated and a new measure of the dendrite morphology is presented to quantify the effect of back diffusion on the amount of secondary phases.
Inmaculada Lopez-Galilea, Stephan Huth, Suzana G. Fries, Nils Warnken, Ingo Steinbach, Werner Theisen, Metallurgical and Materials Transactions A, August 2012

E0261 – Phase Equilibria in the Fe-Nb System

A review of the literature revealed that recently published phase diagrams of the Fe-Nb system show considerable discrepancies regarding phase equilibria with the melt and the homogeneity ranges of the intermetallic phases, specifically of the Laves phase Fe2Nb. Therefore the system has been reinvestigated by metallography, electron probe microanalysis (EPMA), and differ- ential thermal analysis (DTA). Temperatures of invariant reactions were determined and the homogeneity ranges of the two intermetallic phases, Fe2Nb Laves phase and Fe7Nb6 l phase, which both exist within a wide composition range, were established.
S. Voß, M. Palm, F. Stein, D. Raabe, Journal of Phase Equilibria and Diffusion Vol. 32 No. 2, 2011

E0259 – Thermodynamic Assessment of the Cu-Fe-O System

The system Cu-F-O was assessed with CALPHAD technique using computerized optimization procedure (PARROT). Two solid phases CuFe2O4 and Fe3O4 forming solid solution at high temperatures were modeled with compound energy formalism. Presence of Cu1+ on tetrahedral sites in the samples with compositions close to CuFe5O8 reported in the literature was taken into account. The second ternary compound, CuFeO2, was modeled as a stoichiometric phase. For the liquid phase, an ionic two-sublattice model was used. In total 17 adjustable parameters were optimized (9 for the spinel phase, 2 for the delafossite and 6 for the liquid phase) to describe the experimental data. The consistent dataset, which gives a description of the properties from 923 to 1273 K, was obtained.
Alexandra V. Khvan, Olga B. Fabrichnaya, Galina Savinykh, Robert Adam, Hans J. Seifert, Journal of Phase Equilibria and Diffusion Vol. 32 No. 6 2011

E0258 – Liquidus Projection and Reaction Scheme of the Co-Al-Nb System

By metallographic observation of the as-cast microstructures, determination of the liquidus temperatures and the temperatures of invariant reactions by differential thermal analysis, and mea- surement of the compositions of the primary phases and the eutectic residuals by electron probe miroanalysis, a liquidus projection for the Co-Al-Nb systemhas been established for the first time. The binary Co-Nb intermetallic phases have a large solid solubility for Al and their melting temperatures increase markedly by the addition of Al. The only ternary compound, the Heusler phase NbCo2Al, melts incongruently at about 1485 °C. ByCALPHADmodelling the consistency of the experimental data has been checked. Calculated and experimentally determined temperatures of the invariant reactions are in good agreement and are summarised within a reaction scheme.
M. Palm, C. He, O. Dovbenko, F. Stein, J.C. Schuster, Journal of Phase Equilibria and Diffusion Vol. 33 No. 3, 2012

E0257 – Phase equilibria in the oxide system Nd2O3-K2O-P2O5

A phase equilibria diagram of the partial system NdPO4-K3PO4-KPO3 has been developed as part of the research aimed at determining the phase equilibriumrelationships in the oxide system Nd2O3-K2O-P2O5. The investigations were conducted using thermoanalytical techniques, X-ray powder diffraction analysis and reflected-light microscopy. Three isopleths existing between: K3Nd(PO4)2-K4P2O7, NdPO4-K5P3O10 and NdPO4-K4P2O7 have been identified in the partial NdPO4-K3PO4-KPO3 system. Previously unknown potassium-neodymium phosphate “K4Nd2P4O15” has been discovered in the latter isopleth section. This phosphate exists in the solid phase up to a temperature of 890°C at which it decomposes into the parent phosphates NdPO4 and K4P2O7. Four invariant points: two quasi-ternary eutectics, E1 (1057°C) and E2 (580°C) and two quasi-ternary peritectics, P1 (1078°C) and P2 (610°C), occur in the NdPO4-K3PO4-KPO3 region.
Irena Szczygiel, Teresa Znamierowska, Dagmara Mizer, Solid State Sciences 12 (2010) 1205-1210

E0256 – Phase equilibria in the partial system CePO4–K4P2O7–KPO3

The CePO4–K4P2O7–KPO3 portion of the oxide Ce2O3–K2O–P2O5 system has been investigated using thermoanalytical methods, powder X-ray diffraction, XPS and IR spectroscopy. The phase diagram with liquidus isotherms and isothermal section at room temperature of the system CePO4–K4P2O7–KPO3 has been determined. One section, CePO4–K5P3O10, which is quasi–binary only in the subsolidus region (below 560°C), have been found. The system contains one double phosphate K4Ce2P4O15, which exists only in solid state, below 880°C.
Irena Szczygie?, Solid State Sciences 8 (2006) 178–184

E0255 – New intermetallic compounds in the Ce–Pt system

The Ce-rich part of Ce–Pt phase diagram has been investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD), optical and electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Two new intermediate phases, Ce5Pt3 and Ce5Pt4, have been discovered and found to crystallize with tetragonal Pu5Pd3-type structure and orthorhombic Ge4Sm5-type structure, respectively. All the Ce-rich compounds of the system were found to crystallize with a peritectic type formation. We have determined the temperatures of the peritectic plateaus and established the liquidus curves up to 1500°C.
A. Janghorban, M. Lomello-Tafin, J. M. Moreau, Ph. Galez, J Therm Anal Calorim (2011) 103, 137–140

E0254 – Structural Stability of Platinum-Group-Metal-Modified ? + ?’ Ni-Base Alloys

The structural and surface stabilities of two experimental ?-Ni+ ?'-Ni3Al-base alloys containing Pt or Ir were investigated. These alloys are representative of alloys currently being developed to occupy a unique domain with a good combination of high-temperature strength and resistance to oxidation and hot corrosion. Structural characterization included differential thermal analysis (DTA), transmission synchrotron X-ray analysis, precipitate morphology evolution, phase-partitioning behavior, transmission electron microscopy (TEM), dislocation analysis, and isothermal precipitate-coarsening behavior. Electron microprobe investigations showed that Pt partitions largely to the ?' phase, while Ir partitions more to the c phase. As a consequence, the influence of these two elements on the ?-?' lattice-parameter mismatch was quite different. Specifically, synchrotron X-ray analysis confirmed a positive ?-?' misfit in both the Pt- and Ir-modified alloys in the temperature range 700 °C to 1200 °C; however, the Pt partitioning to the ?' phase resulted in a much larger misfit. The coarsening kinetics of both alloys followed a cubic time dependence and Pt addition was more effective than Ir in slowing the coarsening rate. Thermodynamic predictions about elemental partitioning and about the solidus, liquidus, and ?' solvus temperatures were made using the software package PANDAT; the results of these predictions were compared with experimental measurements.
A.J. Heidloff, J. Van Sluytman, T.M. Pollock, B. Gleeson, Metallurgical and Materials Transactions A, 40A, July 2009, 1529

E0253 – Chromia-Assisted Decarburization of W-Rich Ni-Based Alloys in Impure Helium at 1273 K (1000 °C)

The microstructure and surface stability of two experimental W-rich Ni-based alloys have been studied at 1273 K (1000 °C) in an impure-He environment containing only CO and CO2 as impurities. The alloy Ni-2.3Al-12Cr-12W contained 0.08 wt pct carbon in solution, whereas the second alloy Ni-2.3Al-3Mo-12Cr-12Co-12W contained M6C carbides at the same carbon level. Both alloys, which were preoxidized with ~2.3 lm Cr2O3 layer, were decarburized completely within 50 hours of exposure to the helium gas mixture at 1273 K (1000 °C) via the following chromia-assisted decarburization reaction: Cr2O3 (s)+3Calloy (s) fi 2Cr (s)+3CO (g). Microstructural observations, bulk carbon analysis, and microprobe measurements confirmed that the carbon in solid solution reacted with the surface chromium oxide resulting in the simultaneous loss of chromia and carbon. The Cr produced by the decomposition of the Cr2O3 diffused back into the alloy, whereas CO gas was released and detected by a gas chromatograph. Once the alloy carbon content was reduced to negligible levels, subsequent exposure led to the uninterrupted growth of Cr2O3 layer in both alloys. In the preoxidized alloys, chromia-assisted decarburization rates were slower for an alloy containing carbides compared with the alloy with carbon in solid solution only. The formation of Cr2O3 is shown to be the rate-limiting step in the chromia-assisted decarburization reaction. Exposure of as-fabricated alloys to the impure-He environment led to the formation of a thin layer of Al2O3 (<1 lm) between the substrate and surface Cr2O3 oxide that inhibited this decarburization process by acting as a diffusion barrier.
Raghavendra R. Adharapurapu, Deepak Kumar, Jun Zhu, Christopher J. Torbet, Gary S. Was, Tresa M. Pollock, Metallurgical and Materials Transactions A, 42A, May 2011, 1229

E0245 – Phase Equilibria of the Constituent Ternaries of the Mg-Al-Ca-Sr System

Thermodynamic modeling of the Al-Ca-Sr, Mg-Ca-Sr, Mg-Al-Ca and Mg-Al-Sr systems was conducted using the modified quasichemical model. A self-consistent database has been established for these systems. Mg-Al-Ca and Mg-Al-Sr ternary systems were studied experimentally through microstructure characterization, phase identification, and thermal analysis and thermodynamic modeling based on these experimental fi ndings. It has been observed that the intermetallic compounds in the Mg-Ca, Mg-Sr, Al-Ca, and Al-Sr binary systems dissolve the third component in the respective ternary phase diagrams. In addition, two ternary compounds, Mg56Al40Sr4 and Mg2Al4Ca3, have been reported.
M. Aljarrah, M. Medraj, Jian Li, and E. Essadiqi, JOM, Vol. 61 No. 5, May 2009

E0242 – Stabilization of Thermosolutal Convective Instabilities in Ni-Based Single-Crystal Superalloys: Carbide Precipitation and Rayleigh Numbers

The influence of carbide precipitation on grain-defect formation during unidirectional solidification of experimental single-crystal Ni-based superalloys has been assessed over a wide range of compositions with large variations in Re, W, and Ta. In all instances, carbon additions of up to 0.15 wt pct were determined to be statistically significant with respect to stabilizing against the formation of grain defects, such as freckle chains, during solidification. Assessment of the segregation behavior of the constituent alloying additions via a Scheil-type analysis enabled estimation of critical Rayleigh numbers denoting the onset of thermosolutal convection. Precipitation of Ta-rich MC carbides near the liquidus temperature of the alloy was found to interact strongly with the mechanisms associated with freckle formation. Segregation analyses and phase-transformation temperature measurements were used to assess the corresponding Rayleigh numbers for the experimental alloys and to modify the Rayleigh criterion to account for carbide precipitation. Mechanisms pertaining to the interaction of carbides with the onset of thermosolutal convection are discussed.
S. Tin, T.M. Pollock, Metallurgical and Materials Transactions A, Volume 34A, September 2003—1953

E0240 – Martensitic Transformations, Microstructure, and Mechanical Workability of TiPt

The TiPt phase with the B2 structure has been reported to undergo a reversible displacive transformation to B19 martensite at about 1000°C. This system could, therefore, serve in principle as the basis of a high-temperature shape-memory alloy (SMA). However, very few additional details of the B2 and B19 forms of TiPt have been published. In the present work, the B19®B2 transformation temperatures previously reported are confirmed, but the B2 ? B19 temperatures are found to be about 40°C lower than previously accepted. The hardness of B19 martensite shows a minimum at a stoichiometry of ~ 50 at. pct Pt. Between 45 and ~ 50 at. pct Pt, the B2 ? B19 transformations appear to take place in a complex sequence, with up to two intermediate phases being stable over a range of about 50°C. No evidence for this intermediate phase was found for Pt contents from 50 to 56 at. pct Pt. It is clear that a Pt content of about 50 at. pct marks a significant change in the nature of the TiPt phase and its martensite or martensites. It was also found that TiPt has a slightly wider stability range than is shown in the current phase diagram, extending from 45 to 56 at. pct Pt at 1300°C.
T. Biggs, M.B. Cortie, M.J. Witcomb, L.A. Cornish, Metallurgical and Materials Transactions A, Volume 32A, August 2001—1881

E0239 – Study of DTA method experimental conditions and of their influence on obtained data of metallic systems

Differential thermal analysis (DTA) is one of the methods that are suitable for obtaining of thermo-physical and thermo-dynamical data. This method enables determination of temperatures and latent heats of phase transformations of metallic systems. This paper deals with the influence of the experimental conditions settings of the used DTA method on the obtained data. The paper is focused on the study of heating rate and sample mass influence on shift of phase transformations’ temperatures of Fe sample. Research was aimed at high temperature region. Melting region was studied. DTA measurements were realised using Setaram Setsys 18TM laboratory system. Controlled heating of Fe samples (with different mass) was conducted at the following rates: 1, 2, 5, 10, 20 K/min. On the basis of adjusted experimental conditions (different heating rates and different sample masses), the experimental data set was obtained and corresponding dependencies were derived. Using corresponding dependencies the corrections can be applied to reduce the influence of experimental conditions on studied data of investigated alloys (samples). Application of derived dependencies can substantially lead to reduction (minimization) of the influence of experimental conditions, and extrapolation to the so called “zero” mass and “zero” heating rate is possible.
Monika Žaludova, Bed?ich Smetana, Simona Zla, Jana Dobrovska, Karel Gryc, Karel Michalek, Rostislav Dudek, Metal 2012 conference, 23-25. 5. 2012, Brno, Czech Republic

E0237 – Cu9Ni6Sn: Determination of Phase Transformation at High Temperature

The copper rich corner of the CuNiSn system is frequently studied for the high tensile strength and good electrical conductivity of the alloys. In this study, we focus on the phase transfor- mations at high temperature. The incipient melting is studied in some detail just below 1000 °C since the presence of an unexpected peak at 985 °C on the DTA’s thermograms is detected.
A. Deraisme, C. Servant, D. Pachoutinsky, Y. Bienvenu, J.-D. Bartout, L.-T. Mingault, P. Bertrand, R. Bailly, Journal of Phase Equilibria and Diffusion Vol. 31 No. 2 2010

E0234 – Etude des évolutions microstructurales et comportement mécanique des alliages base nickel 617 et 230 à haute température

Afin de répondre aux contraintes sévères subies par les parties chaudes du circuit de refroidissement du VHTR (Very High Temperature Reactor) contenant de l’hélium en sortie des Réacteurs à Haute Température, l’alliage base nickel en solution solide Inconel 617 a été sélectionné dans les années 1980 pour le projet allemand grâce à ses propriétés mécaniques, sa stabilité thermique et sa résistance à la corrosion. L'ATD est utilisée pour caractériser les évolutions de microstructure des matériaux
Chomette Sébastien, Thèse Université de Toulouse, Novembre 2009

E0232 – Effects of Liquid Quenching and Subsequent Heating on the Structure of Co–Al Alloys

The phase composition and structure of Co–Al alloys after liquid-quenching (LQ) and subsequent heating were determined by x-ray diffraction, differential thermal analysis, and differential scanning calorimetry. The phase composition of the LQ alloy and the lattice parameters of the intermetallic phase CoAl and solid solution corresponded to a solidification temperature of 1100 °C, rather than to the eutectic temperature (1400°C). Heating to 1000°C brought the alloy to the equilibrium state. In the range 25–28 at % Al, the LQ alloys were single-phase and consisted of Co-enriched CoAl (B2). Decomposition of this intermetallic phase during heating in the calorimeter gave rise to an exothermic peak at 680°C and led to precipitation of hcp Co. The activation energy of the decomposition process, evaluated by the Kissinger method, was Ea = 125 ± 10 kJ/mol.
V. K. Portnoi, K. V. Tretyakov, S. E. Filipova, J. Latuch, Inorganic Materials, Vol. 41, No. 4, 2005, pp. 350–355

E0230 – Cascade of Peritectic Reactions in the B-Fe-U System

The solidification paths for UFeB4, UFe3B2 and UFe4B, ternary compounds, situated along the U:(Fe,B) = 1:5 line in the B-Fe-U phase diagram, are proposed based on x-ray powder diffraction measurements, differential thermal analysis, heating curves and scanning electron microscopy observations complemented with energy and wavelength dispersive x-ray spectroscopies. The compounds melt incongruently and are formed by peritectic reactions. The present work demonstrates the existence of a cascade of peritectic reactions along the U:(Fe,B) = 1:5 composition line, establishes peritectic temperatures and proposes an isopleth diagram along this line.
M. Dias, P.A. Carvalho, A.P. Dias, M. Bohn, N. Franco, O. Tougait, H. Noël, A.P. Gonçalves, Journal of Phase Equilibria and Diffusion Vol. 31 No. 2 2010

E0219 – Investigation of Selected Thermo-physical Properties of Ternary Sn-Zn-Al Alloys Using DTA

The paper deals with the investigation of temperatures and latent heats of phase transformations of two binary alloys Sn-Zn and five ternary Sn-Zn-Al alloys using the DTA method. The investigated alloys belong to the area of the so called eutectic „valley“ of the Sn-Zn-Al system. DTA of investigated samples was performed at the rate of heating/cooling of 4°C/min. In this way there were obtained temperatures of phase transformations of the ternary system Sn-Zn-Al, temperature of ternary eutectics TE1 197.6°C, temperature of liquidus, and other transformations. Latent heats of melting and solidification were calculated. Latent heat of melting of alloys varies within the interval 71-91 J?.g-1, solidification within the range 73-99 J?g-1. Theoretical isoplethic phase diagrams were created with use of the software MTData and Pandat. Experimental data were compared with the calculated temperatures. It follows from bibliographic searches that description of behaviour of ternary system Sn-Zn-Al is still not quite known. The Sn-Zn-Al alloys could become a suitable alternative substitute of lead based solders for temperatures up to 350°C.
Bed?ich Smetana, Simona Zlá, Jaromír Drápala, Aleš Kroupa, Kristina Pe?inová, Rostislav Burkovi?, Neželezné kovy a slitiny, Hutnické listy ?.1/2010, ro?. LXIII

E0218 – Phase transformation temperatures of pure iron and low alloyed steels in the low temperature region using DTA

The paper reports a study of temperatures of phase transitions of nine samples of real grades of low-alloyed steels, including one sample of pure iron, using differential thermal analysis. Temperatures of phase transitions were measured in the low-temperature interval (20–10008C). Investigated systems were analysed at selected rates of heating/cooling and then temperatures of phase transitions for zero heating/cooling rate were determined. The results obtained are compared with temperatures of the equilibrium metastable diagram Fe–C, with results from the software IDS and with temperatures of phase transitions calculated according to relations published in available literature. It follows from the results that differences, sometimes considerable ones, still exist between experimental and theoretical data, which implies the necessity for further systematic research in this area.
Bedrich Smetana, Simona Zlá, Jana Dobrovská, Petr Kozelsky, Int. J. Mat. Res. (formerly Z. Metallkd.) 101 (2010) 3

E0217 – Contribution à l’étude de la précipitation des phases intermétalliques dans l’alliage 718

Many structural alloys are strengthened by the presence of precipitates in the grains or at grain boundaries. Nickel based superalloys often present an austenitic matrix in which ordered intermetallic phases precipitate. In the alloy Inconel 718, one can find ?' L12 cubic ordered precipitates together with the compound Ni3Nb in its metastable form ?" (D022 - tetragonal) or the stable phase ? (D0a - orthorhombic). The incidence of those precipitates on macroscopic properties of the alloy 718 is well known and widely used in industrial applications. However the mechanisms responsible for the precipitation and transformation of these phases are not fully understood, which motivated the present study. The alloy microstructure has been observed by optical microscopy (OM) and electron microscopy (scanning and transmission, SEM and TEM) in the as received state as well as after heat treatment (isothermal and anisothermal). Differential thermal analysis (DTA) was used to determine the precipitation and dissolution temperatures of the phases ?', ?" and ?. Various precipitation microstructures were obtained by heat treatments based on available TTT diagrams. Some of the structural defects present in ?" and ? precipitates have been characterised by lattice imaging TEM observations. It is shown that stacking faults in phase can act as a seed for the germination of ?. The structure of the interface and the orientation defects in lamellae suggest that the growth of phase occurs directly from the matrix (and not by transformation of the ?’’ phase).
Aliou NIANG, Thèse Université de Toulouse, 2010

E0216 – Thermophysical and structural study of IN 792-5A Nickel based superalloy

The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C·min-1) and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733) equipped with energy dispersive analyser EDAX (EDAM 3).
S. Zla, J. Dobrovska, B. Smetana, M. Žaludova, V. Vodarek, K. Konecna, METABK 2010

E0215 – Application of high temperature DTA to micro-alloyed steels

Paper deals with investigation of phase transitions temperatures for selected real grades of micro-alloyed steels. Temperatures of characteristic phase transitions were obtained using Setaram SETSYS 18TM. The DTA technique was selected for the study of micro-alloyed steels. Temperatures of phase transitions (liquidus, solidus etc.) were obtained. Influence of admixed and alloyed elements on shift of temperatures was investigated. Resulting data were compared with temperatures of phase transitions of Fe-C, Fe-Mn systems and with temperatures calculated according to relations published in available literature. Thermodynamic-kinetic solidification model IDS was used to calculate characteristic equilibrium temperatures of investigated systems.
B. Smetana, S. Zla, M. Žaludova, J. Dobrovska, P. Kozelsky, METABK 2010

E0210 – Application of high temperature DTA technique to Fe based systems

The paper deals with the study of phase transformation temperatures of Fe (Fe-C) based metallic alloys. Influence of heating/cooling rate and composition on shift of phase transformation temperatures is investigated in this paper. Six samples with graded carbon content were investigated. Plasma and vacuum melting was performed to prepare alloys. Liquidus-solidus and ??? region was studied. Temperatures of phase transformations were obtained using DTA and Setaram Setsys 18TM laboratory system. DTA experiments of prepared alloys were conducted under inert atmosphere (Ar, >6N). Controlled rate of heating/cooling of alloys was conducted: 2, 4, 7, 10, 15, 20 K min-1. Aproximation to the equilibrium conditions was achieved. The extrapolation of obtained phase transformation temperatures to a zero heating/cooling rate was performed. Comparison of obtained experimental data with data presented in the literature and IDS results was carried out. It follows from copmarison of obtained results with accessible data in the literature the lack of these data and differencies between them. The knowledge of simple binary system Fe-C behaviour is important for the description of more complex systems; ternary, quaternary,… and multicomponent (steels) also. This study is the base of wide research activity at our department in the future.
Bed!ich Smetana, Monika Žaludova, Simona Zla, Jana Dobrovska, Michal Cagala, Ivo Szurman, Daniel Petlak, Metal 2010, Roznov pod Radhostem,Czech Republic

E0209 – Investigation of relevant phase diagrams for high temperature solder materials: The binary systems Cu-Sn and Cu-Sb

Although solders in the electronic industry have only a relative small contribution to the worldwide consumption of lead, the recycling of the electronic waste is complicated and thus it pollutes the environment. Therefore the electronic industry has tried to substitute the poisonous lead in the solders for less harmful materials during the last decade. Interested alloys are those ones which could include the components of the lead free solder and the substrate materials. This work concentrates on the experimental research of the binary systems Cu-Sn and Cu-Sb. Experimental techniques are the powder X-ray diffraction at normal and higher temperatures (PXRD / HTPXRD), thermal analysis (DTA) and metallographic methods (EPMA / ESEM).
Siegfried Fürtauer, Thesis, University of Vienna, 2010

E0208 – The Structure and Stability of High Temperature Intermetallic Phases for Application within Coating Systems

The reduction of noise and emissions is becoming increasingly important in civil aircraft jet engines as well as requirements for reduced fuel consumption and improved efficiency. This has resulted in the drive towards increasing turbine entry temperatures and the development of thermal barrier coatings (TBCs). Due to the effectiveness of the platinum-modified nickel aluminides currently used as bond coat layers for Ni-based superalloy TBCs, higher temperature ruthenium-containing bond coat layers are being examined as a possible low cost alternative to platinum.The aim of this research was to examine the stability of various phases within platinum and ruthenium-containing multilayer systems formed during the above reaction process and to determine the most stable intermetallics for inclusion in future coating systems. Foil samples were manufactured using multilayer sputter coating methods and the exothermic formation of these phases was examined using differential scanning calorimetry. The identification of the phases formed was carried out using X-ray diffraction.
Tracey Roberts, Thesis, Cranfield University November 2009

E0204 – Thermal stability and glass forming ability of cast iron-phosphorus amorphous alloys

The effect of P addition on the thermal stability and on the glass forming ability (GFA) of bulk amorphous sheets and melt-spun ribbons of cast iron Ci(100-x)Px (x = 1.56, 3.1, 4.63, 6.14, 7.63, 9.1 at.%) was studied by calorimetric measurements. Bulk amorphous sheets of 1mm x 4mm transverse cross-section were prepared by centrifugal copper mold casting. For the as-quenched ribbons, it was found that only for x = 7.63 and 9.1 glass transition temperatures Tg were detected. The reduced glass transition temperatures Tg/Tl (where Tl is the liquidus temperature) are 0.542 and 0.551, respectively. The as-quenched melt-spun ribbons and the bulk amorphous sheets have nearly the same thermal transition and glass forming ability characteristics.
M. Shapaan, A. Bardos, L.K. Varga, J. Lendvai, Materials Science and Engineering A366 (2004) 6-9

E0203 – The crystal structure of zeta1-Al3Cu4

The crystal structure of the zeta1-phase Al3Cu4 was determined by means of X-ray powder diffraction: a = 812.67(3) pm, b = 1419.85(5) pm, c = 999.28(3) pm, space group Fmm2, Pearson symbol oF88-4.7, RI = 0.0633. The structure represents a distinctive 2a x 2?3a x 2c superstructure of a metal-deficient Ni2In-related structure. The ordering of the minor component and the vacancies in the atomic layers of hexagonal topology fulfill the principle of maximal self-avoidance.
L.D. Gulay, B. Harbrecht, Journal of Alloys and Compounds 367 (2004) 103-108

E0194 – Crystallization behavior of Fe62Nb(8-x)ZrxB30 bulk amorphous alloy

The effect of Zr addition on the glass-forming ability has been investigated in the Fe62Nb(8-x)ZrxB30 bulk amorphous alloy system by thermal (differential scanning calorimeter (DSC) and differential thermal analysis (DTA)) and structural (X-ray diffractometry (XRD) and high-resolution transmission electron microscope (HRTEM)) analysis. Zr addition reduces the bulk glass-forming ability (BGFA) and changes the microstructure obtained after crystallization. The Kissinger method was used to estimate the activation energy (Ea) of crystallization. A strong correlation between Ea and BGFA parameters was observed. Among the crystallization products the metastable Fe23B6 phase appeared, which is probably a consequence of the Nb content in the alloy.
M. Shapaan, J. Labar, J. Lendvai, L.K. Varga, Materials Science and Engineering A 375-377 (2004) 789-793

E0193 – Crystallization behavior of (Fe(100-x)Cox)62Nb8B30 bulk amorphous alloy

The effect of Co addition on the glass-forming ability (GFA) has been investigated in the (Fe(100-x)Cox)62 Nb8B30 (x = 0, 33, and 50) bulk amorphous alloy system by differential scanning calorimeter (DSC). The thermal stability measured by the apparent activation energies decreased from about 5.5 to 4.5 eV upon Co addition. The glass-forming ability measured by the temperature interval Tx - Tg was decreased substantially compared to Fe62Nb8B30 alloy, but it is still large enough for practical applications. The DSC and DTA parameters, Tg, Tx, Tm and Tl were combined in different parameters, Tg/Tm, Tx/Tl and Tx/(Tg + Tl) and Tx/(Tl - Tg) to express the glass-forming ability. The cystallization products were studied by XRD. The metastable Fe23B6 crystallization product was found in all the alloys.
M. Shapaan, J. Gubicza, J. Lendvai, L.K. Varga, Materials Science and Engineering A 375-377 (2004) 785-788

E0192 – Influence of the wheel speed on the thermal behaviour of Cu60Zr20Ti20 alloys

The effect of the wheel velocity's strong influence on the glass forming ability (GFA), the thermal stability and the crystallization kinetics of ductile Cu60Zr20Ti20 ribbons has been studied. The samples were characterised by differential scanning calorimetry (DSC) using continuous heating and isothermal annealings, X-ray diffraction and microhardness. The DSC measurements revealed that the higher wheel speed results in a higher glass transition (Tg) and higher crystallization temperature (Ton). Independent of wheel speed, the crystallization takes place in a two-stage process. From the isothermal treatment, the crystallization kinetics was analysed using the Avrami model. The microhardness exhibits a linear relationship as a function of the crystallized volume fraction. A perfect solute mixture model of defect free nanoparticles embedded in an amorphous matrix was used to account for this strengthening mechanism.
A. Révész, A. Concustell, L.K. Varga, S. Surinach, M.D. Baro, Materials Science and Engineering A 375-377 (2004) 776-780

E0190 – Revised phase diagram for the Pt-Ti system from 30 to 60 at.% platinum

Alloys of the Ti-Pt system between 30 and 61 at.% Pt were studied using metallography with optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential thermal analysis (DTA). A phase of nominal composition Ti4Pt3, in the range 41.7-43.4 at.% Ptwas found in samples containing between 30 and 47 at.% Pt, andwas apparently formed by a peritectoid reaction between beta-TiPt and Ti3Pt at 1205 ± 10°C. The eutectic reaction betweenTi3Pt and -TiPtwas found to be at ~35 at.% Pt and 1424 ± 10°C, and theTi3Pt phase melted at circa 1500°C. The other phase boundaries agreed with the published literature, except that a slightly wider range was found at 1200°C for beta-TiPt.
T. Biggs, L.A. Cornish, M.J. Witcomb, M.B. Cortie, Journal of Alloys and Compounds 375 (2004) 120-127

E0179 – Mixed crystals in the system Cu2MnGexSn(1-x)S4: Phase analytical investigations and inspection of tetrahedra volumes

Cu2MnGeS4 crystallizes orthorhombic in a wurtzite superstructure type while Cu2MnSnS4 crystallizes in a tetragonal sphalerite superstructure type. Lattice constants and thermal analyses of the solid solution series Cu2MnGexSn(1-x)S4 are presented. A two-phase region is found from Cu2MnGe0.3Sn0.7S4 to Cu2MnGe0.5Sn0.5S4. The cell volume of the mixed crystals increases with increasing Sn content. The melting points increase smoothly with increasing Ge content to x = 0:5 and then steeply for higher Ge contents. The single crystal X-ray structure analysis of Cu2MnGe0.55Sn0.45S4 is presented. The refinement converges to R = 0:0270 and wR2 = 0:0586, Z is 2. The volumes of the tetrahedra [MS4] (M = Cu, Mn, Ge, Sn) are calculated. From these volumes the differences in size of the tetrahedra are derived and compared with the corresponding differences in the end members of the solid solution series. It turns out that the resulting structure type in these materials depends on the volume differences of the constituting tetrahedra [MS4].
T. Bernert, M. Zabel, A. Pfitzner, Journal of Solid State Chemistry 179 (2006) 849-854

E0175 – Influence of the Ti/Zr ratio and the synthesis route on hydrogen absorbing properties of (Ti(1-x)Zrx)Mn1.5V0.5 alloys

The hydrogenation properties of two pseudo-binary Ti(1-x)ZrxMn1.5V0.5 alloys with x=0.15 and 0.5 obtained by arc melting and mechanical alloying have been studied. All alloys crystallize in the hexagonal C14 Laves phase. Arc-melted alloys are microcrystralline and exhibit local variations of Ti and Zr contents which are not overcome by annealing treatments. As for milled alloys, agglomerated nanocrystallites (~9 nm in diameter) are obtained after subsequent thermal annealing at 800°C. For high Zr-contents, a better chemical homogeneity is obtained by the milling route. Whatever the synthesis route is, the hydrogen equilibrium pressure decreases with increasing Zr content due to cell-volume increase of the intermetallic compound. As concerns kinetics, very fast hydrogenation rates of few seconds are obtained at room temperature, particularly for milled alloys.
B. Villeroy, F. Cuevas, J. Bettembourg, P. Olier, M. Latroche, Journal of Physics and Chemistry of Solids 67 (2006) 1281-1285

E0171 – Pt29Zn49, a complex defective AlB2-type derivative structure

The crystal structure of the title compound has been determined by X-ray diffraction means. Pt29Zn49 forms a complex superstructure of a defective AlB2-type derivative of the order 58: a = 279.0(1) pm, b = 11895.2(4) pm, c = 698.0(1) pm, space group Amm2, Z = 2. Ordering of vacancies is accompanied by a particular distortion of defective graphite-like 63 nets consisting exclusively of Zn atoms. The ordering induces a modulation of the structure along ah of an AlB2-type structure with a periodicity of nearly 12 nm. A mechanistic model is proposed elucidating how Pt29Zn49 evolves from the eutectoid decomposition of the inter-mediate high temperature precursor Pt7Zn12.
S. Thimmaiah, B. Harbrecht, Journal of Alloys and Compounds 417 (2006) 45-49

E0168 – Cytotoxicity of Zr-based bulk metallic glasses

Recently we developed a family of Ni-free Zr-based bulk metallic glasses in the Zr-Cu-Fe-Al system. X-ray diffraction and differential thermal analysis measurements demonstrate its good glass-forming ability, and amorphous rods of up to 13 mm in diameter can be produced for the alloy Zr58Cu22Fe8Al12. This new glassy system is potentially very interesting for biomedical applications. Thus we have investigated the effect of surface modification (treatment with nitric acid and oxygen plasma) on the alloy's cytotoxicity and compared it with the results for a Ni-bearing Zr-based bulk metallic glass. The surfaces were analyzed by X-ray photoelectron spectroscopy, and cytotoxicity was tested by measuring the viability and metabolic activity of mouse fibroblasts. Our results show that the surfaces of the as-cast glasses consist almost exclusively of zirconium oxide, which yields good biocompatibility. With nitric acid treatment this oxide layer can be stabilized further, to the extent that the cytotoxicity becomes as good as that of the non-toxic negative control (polystyrene).
S. Buzzi, K. Jin, P.J. Uggowitzer, S. Tosatti, I. Gerber, J.F. Löffler, Intermetallics 14 (2006) 729-734

E0158 – Phase equilibria and phase transformations in the Ti-rich corner of the Fe-Ni-Ti system

While the main features of the Fe-Ni-Ti system are well known at low Ti content, literature review of the Ti-rich corner revealed inconsistencies between experimental reports. This investigation presents new experimental results, defined to remove the uncertainties concerning melting behavior and solid-state phase equilibria of the (Ni,Fe)Ti2 phase with the adjacent (Fe,Ni)Ti (B2, CsCl-type structure) and beta-Ti (A2, W-type) phases. Six samples have been prepared and examined by differential thermal analysis performed in yttria and alumina crucibles, and by scanning electron microscopy in the as-cast state as well as equilibrated at 900°C.
P. Riani, G. Cacciamani, Y. Thebaut, J. Lacaze, Intermetallics 14 (2006) 1226-1230

E0156 – Magnetically soft nanomaterials for high-temperature applications

Nanomaterials for high-temperature applications must meet two basic requirements: (i) very soft magnetic behaviour at elevated temperature, and (ii) stable properties at elevated temperature for a long time (application time). The latter requirement is related to thermal stability of nanocrystalline structure of these materials. The paper presents the current status of research in the field of magnetically soft nanocrystalline materials, highlighting the influence of alloy composition on magnetic properties and their stability at elevated temperatures during very long time annealing (several thousands of hours at temperature up to 550°C). It was found that modification of the alloys allows to tailor their chemical composition and manufacturing process to particular application temperature requirements. FINEMETs are the most suitable materials for application at temperature, T, up to 300°C, FINEMET modified by cobalt (Fe0.6Co0.4)73.5Cu1Nb3Si13.5B9 (at.%) for T = 300-350°C, NANOPERM for T = 350-400°C and HITPERM (Fe0.6Co0.4)86Hf7B6Cu1 for T = 400-550°C.
T. Kulik, J. Ferenc, A. Kolano-Burian, X.B. Liang, M. Kowalczyk, Materials Science and Engineering A 449-451 (2007) 397-400

E0155 – High temperature behavior of ball-milled Al-Ni-Ce-Co alloys

Microstructure of ball-milled Al85Ni8Ce5Co2 powder indicates the formation of fine nanoparticles with some amorphous fraction. Thermal analysis revealed that the release of internal stress and grain growth is followed by the redistribution and possible melting of high solute concentration interfaces. In addition, mechanical properties of compacted powder specimens were also investigated.
A. Révész, P. Henits, Zs. Kovacs, Journal of Alloys and Compounds 434-435 (2007) 424-427

E0153 – Preparation of nanocrystalline Mn-Al-C magnets by melt spinning and subsequent heat treatments

Mn54Al44C2 ribbon samples have been prepared by melt spinning in a single-phase epsilon hexagonal disordered state and its exothermal transformation at around 500°C into a tetragonal L10 type magnetic structure (t-phase) was followed by DTA, DSC, X-ray diffraction and thermomagnetic measurements. The metastable t-phase stabilized by carbon addition could be transformed reversibly into the epsilon-phase at around 800°C, without decomposition into the stable Al8Mn5 and beta manganese phases. The almost constant Curie temperature obtained for partially transformed two-phase samples indicated a compositionally invariant transformation. By grinding the thin (25 µm) ribbon into sub-millimeter flakes, a bulk anisotropic magnet could be compacted by magnetic field oriented powder technology.
E. Fazakas, L.K. Varga, F. Mazaleyrat, Journal of Alloys and Compounds 434-435 (2007) 611-613

E0151 – Magnetically soft nanomaterials for high-temperature applications

The paper summarizes the current status of research in the field of magnetically soft nanocrystalline materials especially highlighting the influence of alloy composition on structure and magnetic properties as well as their stability at elevated temperature during very long time annealing (several thousand hours at temperature up to 550°C). Modification of the alloys allows to tailor their chemical composition and manufacturing process to particular application temperature requirements. FINEMET is the most suitable material for application at temperature up to 300°C, FINEMET modified by cobalt (Fe0.6Co0.4)73.5Cu1Nb3Si13.5B9 for 300°C
T. Kulik, J. Ferenc, A. Kolano-Burian, X.B. Liang, M. Kowalczyk, Journal of Alloys and Compounds 434-435 (2007) 623-627

E0148 – Effect of Pb addition on ageing behavior of AZ91 magnesium alloy

The ageing behavior of AZ91 alloy containing 2 wt.% lead is investigated. The results show that addition of Pb suppresses the discontinuous precipitation and thereby slows down the ageing kinetics. Even though the peak hardness obtained for both alloys is almost same, the peak hardness reaches after 2400 min for Pb added alloy against 900 min for the base alloy. The presence of Pb in solid solution might have inhibited the diffusion of Al and Mg atoms, which is essential for the formation, and growth of discontinuous precipitation in this alloy.
A. Srinivasan, U.T.S. Pillai, B.C. Pai, Materials Science and Engineering A 452-453 (2007) 87-92

E0144 – X-ray diffraction, 119Sn Mössbauer and thermal study of SnSe-Bi2Se3 system

The phase equilibrium diagram of the SnSe-Bi2Se3 system has been re-investigated using X-ray powder diffraction, thermal analysis (DTA and DSC) and 119Sn Mössbauer spectroscopy data. It shows solid solutions based on Bi2Se3 and SnSe ( alpha and beta forms) and three intermediate phases: well-defined, SnBi4Se7, SnBi4Se7, and a new phase Sn2Bi2Se5. The new phase Sn2Bi2Se5 exists in the composition range 25-55 mol% Bi2Se3. Its structure is still under study. However, 119Sn Mössbauer spectroscopy study of the latter allowed to achieve a well knowledge of the local environment of tin atoms and could contribute to the actual structural study.
K. Adouby, M.L. Elidrissi Moubtassim, C.P. Vicente, J.C. Jumas, A.A. Touré, Journal of Alloys and Compounds xxx (2007) xxx-xxx

E0130 – Chemical inhomogeneity of intermetallic phases precipitates formed during solidification of Al-Si alloys

In this work, the results of an examination of the solidification process of the AlSi6 and AlSi12 alloys as influenced by the content of the transition metals, Fe, Mn and Cr, are presented. The concentration of these elements in alloys prepared from pure components has been changed in the following range: Fe 0.5-3 wt.%, Mn 0-2 wt.% and Cr 0.3 wt.%. The thermal effects during solidification of alloys at a cooling rate of 3.3 K/min (between liquidus and solidus) connected with forming of structural components of alloy were determined. The temperature of the phase transformations was evaluated and correlated with chemical composition of alloys. It was stated that, on an average, an increase in Fe and Mn content of about 1 wt.% increases the temperature of primary proeutectic iron-bearing phase precipitation by about 40 K (in the examined range of the alloys compositions). By means of microscopic observations of the alloy microstructure, the morphology of the primary phase precipitates frozen at a chosen temperature was estimated. On the basis of the results of X-ray microanalysis (EDS), the chemical composition of the primary iron-bearing phases was analysed, and a relation among the components (i.e., Al, Si, Fe, Mn and Cr) was established. The sequence of microstructural component formation during solidification of the alloys examined was presented.
M. Warmuzek, W. Ratuszek, G. Sek-Sas, Materials Characterization 54 (2005) 31-40

E0127 – Effect of strontium and cooling rate upon eutectic temperatures of A319 aluminum alloy

DTA analysis was used to investigate the solidification reactions of alloy A319 with either 12 or 136 ppm of Sr added. Strontium does not affect primary solidification of (Al) dendrites but modifies the kinetics of the (Al)-Si eutectic. The effects of Sr level and of cooling rate on the characteristic temperatures for the (Al)-Si and other eutectic reactions are described.
E.J. Martinez D., M.A. Cisneros G., S. Valtierra, J. Lacaze, Scripta Materialia 52 (2005) 439-443

E0125 – Delineation of phase fields at the Te-rich end of the Ru-Te binary system

The tellurium rich side of the ruthenium-tellurium binary system was studied by differential thermal analysis. To avoid reported problems of Te loss by evaporation and reactive interference of Te to the thermocouples of the thermal analyzer, the present study made use of specially designed sealed quartz capsules as DTA containers. The thermal analyses were carried out over the compositional range of 0.66 < xTe < 1.00 with the help of SETARAM TG/DTA and other indigenously built thermal analyzers available in this laboratory. The thermal data generated for fifteen different compositions were interpreted for the nature of phase transitions occurring at their characteristic temperatures. The Ru-Te binary system was found to have a eutectic transformation at 444°C at a composition of xTe = 0.918 and a monotectic transformation at 447°C at a composition of xTe = 0.700. Up to 6 at.% Ru is soluble in Te at about 440°C.
M. Ali (Basu), S.R. Bharadwaj, D. Das, Journal of Nuclear Materials 340 (2005) 214-218

E0124 – Equilibrium phase diagram of the Ag-Au-Pb ternary system

The phase diagram of the ternary system Ag-Au-Pb has been established using differential thermal analysis and X-ray powder diffraction analysis. Four vertical sections were studied: XPb = 0.40, XAu/XPb = 1/3, XAg/XAu = 4/1 and XAg/XAu = 1/1. Two ternary transitory peritectics and one ternary eutectic were characterized. A schematic representation of the ternary equilibria is given.
S. Hassam, Z. Bahari, Journal of Alloys and Compounds 392 (2005) 120-126

E0117 – Contribution à l’étude du système quasi-binaire ZrAu-CeAu

A. Ait Chaou, M. Lomello-Tafin, P. Lejay, J. Allemand, Ph. Galez, 30ieme JEEP (2005) 87-88

E0116 – Phases and phase equilibria in the Fe-Al-Zr system

F. Stein, G. Sauthoff, M. Palm, Z. Metallkd. 95 (2004) 469-485

E0113 – Equilibres solide-liquide dans le système Al-Fe-Si

S. Pontevichi, M. Peronnet, F. Bosselet, J.C. Viala, J. Bouix, 28ème JEEP (2002)

E0107 – The ruthenium-tin system.

The Ru---Sn liquid-solid and some solid-solid equilibria have been completely revised by means of differential thermal analysis, X-ray powder diffraction and microprobe investigations. The existence of two intermetallic phases has been clearly established: Ru0.4Sn0.6 decomposed by a peritectic reaction at 1266(± 4)°C and Ru0.1Sn0 - congruently melting at 1257(± 2)°C.
L. Perring, P. Feschotte, F. Bussy and J.C. Gachon, Journal of Alloys and Compounds 245 (1996) 157-163

E0106 – The germanium-ruthenium system.

L. Perring, P. Feschotte and J.C. Gachon, Journal of Phase Equilibria 17 (1996) 101-106

E0105 – Brasage d’aciers réfractaires par des poudres de brasage à base de nickel.

J.D. Bartout, Y. Bienvenu, A. Germidis and J. Favennec

E0100 – The Ag + Au + Pb system : determination of the liquidus surface

The liquidus surface of the Ag + Au + Pb system has been determined by differential thermal analysis. In the temperature range 973-298 K, experiments were performed along the four following sections: = with 0
S. Hassan, M. Gambino, J.P. Bros, Thermochimica Acta 257 (1995) 83-92

E0075 – Quelques possibilités d’application de l’analyse thermique différentielle pour l’étude de l’élaboration par la métallurgie des poudres

Y. Bienvenu, J.C. Le Flour, M. Jeandin

B3351 – Study of order–disorder transitions in Fe–Ge alloys and related anelastic phenomena

Several methods were used to study the phase transitions and related anelastic mechanisms in some alloys of the Fe–Ge system. Obtained results show the appearance of the DTA and dilatometric effects at temperature 200–350 °C due to ordering process corresponding to the peak on internal friction curves (denoted as the P3 peak in this paper). The formation of ordered structure in Fe–Ge system at low Ge concentration is sensitive to the thermal history of the specimen. The formation of the ordered structure (with activation energy of ordering H ? 1.14 eV for a concentration of 12 at.% Ge) leads to the increase in the microhardness of studied alloys
Zehira Belamri, Djamel Hamana, Igor S. Golovin, Journal of Alloys and Compounds 554 (2013) 348–356

B3350 – Enthalpy of mixing of liquid Ag-Bi-Cu alloys at 1073K

The Ag–Bi–Cu system is among those ternary systems which have not been fully studied yet, in particular the thermodynamic description of the liquid phase is missing. Partial and integral enthalpies of mixing of liquid ternary Ag–Bi–Cu alloys were determined over a broad composition range along six sections: x(Ag)/x(Bi) = 0.25, 1, 4; x(Ag)/x(Cu) = 1.5; x(Bi)/x(Cu) = 1.86, 4. Measurements were carried out at 1073 K using two Calvet type microcalorimeters and drop calorimetric technique. It was found that integral enthalpies of mixing are small and endothermic, similarly to limiting binary alloys. The ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions. There are no significant additional ternary interactions.
P. Fima, H. Flandorfer, Thermochimica Acta (2013)

B3349 – Heat capacities of several Co2YZ Heusler compounds

Heat contents of several Co2-based Heusler compounds Co2YZ (Y = Fe, Mn, Ti; Z = Al, Ga, Si, Ge, Sn) were measured from 500 K to 1500 K using a Setaram MTHC 96 drop calorimeter. Second order polynomials were adopted to fit the data and heat capacities were obtained by taking the derivatives with respect to temperature. Melting points were determined by differential scanning calorimetry (DSC) and measured heats of fusion were compared with those obtained from extrapolation of heat contents
Ming Yin, Philip Nash, Song Chen, Thermochimica Acta 574 (2013) 79– 84

B3347 – Thermodynamic assessment and experimental study of Mg–Gd alloys

The solid solubility of Gd in (Mg) is studied experimentally using microstructure, chemical and EDX analysis on permanent mould chill cast samples which were annealed for 1–14 days at 300–550 °C. Based on those key data and all the critically assessed experimental phase equilibrium and thermodynamic data of the Mg–Gd system two Calphad-type thermodynamic descriptions are developed. This provides calculated phase diagrams, and an inherent inconsistency between the vapor pressure data and the Mg-rich phase diagram is indicated. A previous misperception of “experimental” enthalpy of formation data of binary GdxMgy intermetallic compounds is also revealed. The assumption of systematic trends in these key thermodynamic data for the series of rare earth elements R = (La, Ce, Pr, Nd, Sm, Gd) is scrutinized.
M. Hampl, C. Blawert, M.R. Silva Campos, N. Hort, Q. Peng, K.U. Kainer, R. Schmid-Fetzer, Journal of Alloys and Compounds 581 (2013) 166–177

B3346 – Phase transformation studies in U–Nb–Zr alloy

Phase transformation diagrams provide fundamental informations for designing thermomechanical processes being a must regarding uranium alloys nuclear fuels. The work shows the evaluation of a kinetic transformation diagram for U–7.5Nb–2.5Zr (wt.%) based on both calorimetry experiments and dilatometry allied to X-ray diffraction analysis. Calorimetry measurements in scanning and drop modes can detect enthalpies of heating and transformation onset points from ambient up to select isotherms while the dilatometer is used to scan for sample volume changes related to phase transformations. The resulted kinetic diagram shows the gamma phase is stable for this alloy, guiding the rolling deformation process to temperature ranges where this phase remains for longer periods. Comparing to the literature results, the low temperature transformation (300–400 °C) is shifted to longer times accordingly to the disclosed TTT kinetic diagram. Therefore, two forming process windows can be proposed at 200 °C and 400 °C neighborhood where gamma-phase remains for enough time to accomplish total reduction.
Denise Adorno Lopes, Thomaz Augusto Guisard Restivo, Angelo Fernando Padilha, Nuclear Engineering and Design 265 (2013) 619– 624

B3305 – Thermodynamic evaluation of hypereutectic Al–Si (A390) alloy with addition of Mg

This paper presents the thermodynamic evaluation of A390 hypereutectic Al–Si alloy (Al–17% Si–4.5% Cu–0.5% Mg) and alloys up to 10% Mg, using the Factsage® software. Two critical compositions were detected at 4.2% and 7.2% Mg where the temperatures of the liquidus, the start of the binary and of the ternary eutectic reaction are changed. These critical compositions show differences in the formation of Mg2Si intermetallic particles during the solidification interval. For compositions up to 4.2% Mg, the Mg2Si intermetallic phase first appears in the ternary eutectic zone. With Mg contents between 4.2% and 7.2%, Mg2Si particle appears in both the binary and ternary eutectic reactions. Above 7.2% Mg, it solidifies as a primary phase and also during the binary and ternary reactions. The calculated liquid fraction vs. temperature curves also showed a decrease of the eutectic formation temperature (knee point temperature) with the addition of Mg content up to 4.2% Mg. This temperature becomes almost constant up to 10% Mg. The calculation of eutectic formation temperature shows a good agreement with differential scanning calorimetry (DSC) tests.
Alireza Hekmat-Ardakan, Frank Ajersch, Acta Materialia 58 (2010) 3422–3428

B3300 – Ageing study of Cu–Al–Be hypoeutectoid shape memory alloy

Thermal ageing at constant temperature (350 °C) and under systematically designed temperature-varying conditions were performed on the metastable austenitic phase of hypoeutectoid Cu–Al–Be shape memory alloy. Thermal precipitations and their effects on the alloy global microstructure were studied by DSC, XRD and SEM techniques. Precipitations of equilibrium phases (? + ?2) within the temperature range of 330–370 °C, and their generalization by a discontinuous mechanism for an ageing time of 864 ks (240 h), were identified and analyzed. The results of this study are expected to benefit the applications of copper-based shape memory alloys under various thermal conditions
S.M. Chentouf, M. Bouabdallah, H. Cheniti, A. Eberhardt, E. Patoor, A. Sari, Materials Characterization 61 (2010) 1187-1193

B3298 – Precipitation kinetics of the hardening phase in two 6061 aluminium alloys

The purpose of this work is to study the kinetics of the precipitation of the hardening phase in two Al–Mg–Si alloys. A review of the theoretical framework for solid-state reaction kinetics and the determination of kinetic parameters from DSC curves are provided, then used to quantify ?? precipitation in the two alloys studied. Despite failure to achieve high levels of accuracy, due, in particular, to the dilution of the alloys, the procedure to analyse this precipitation reaction yields valuable results. It is established that ?? precipitates homogenously as needles which grow through an enhanced-diffusion mechanism.
Youcef Aouabdia, Abdelhamid Boubertakh, Smail Hamamda, Materials Letters 64 (2010) 353–356

B3295 – Analysis of the multistage phase separation reaction in Fe–25 at% Co–9at%Mo

Differential scanning calorimetry (DSC) has been used to characterize the phase reactions during age hardening of a Fe–25 at%Co–9 at%Mo alloy. The heat of reaction which can be accounted for the development of the hardening phase was further analyzed on the basis of the Kissinger method and a fit based on the JMA model. Additionally, the precipitation sequence was studied by in situ small-angle neutron scattering (SANS) as well as in situ X-ray diffraction (XRD) to gain knowledge on the chemistry and crystallography of the prevailing phases. As direct imaging techniques 3D atom probe (3DAP) and high-resolution transmission electron microscopy (HRTEM) were used. The combination of these methods revealed that hardening in the investigated alloy starts with spinodally formed Mo-rich clusters followed by precipitation of the intermetallic m-phase (Fe,Co)7Mo6.
Elisabeth Eidenberger, Michael Schober, Thomas Schmoelzer, Erich Stergar, Peter Staron, Harald Leitner, Helmut Clemens, Phys. Status Solidi A 207, No. 10, 2238–2246 (2010)

B3291 – Thermodynamic and Transport Properties of the PrBr3-KBr Binary System

Phase equilibrium in the PrBr3?KBr binary system was established from differential scanning calorimetry (DSC). This system exhibits three compounds, K3PrBr6, KPrBr5, and KPr2Br7, and two eutectics located at a mole fraction of PrBr3 (x = 0.182; 849 K and x = 0.552; 753 K), respectively. K3PrBr6 forms at 727 K and melts congruently at 904 K. K2PrBr5 melts incongruently at 847 K, and finally KPr2Br7 forms at 697 K and melts incongruently at 786 K. The electrical conductivity of PrBr3?KBr liquid mixtures was measured down to temperatures below solidification over the whole composition range. Results obtained are discussed in terms of possible complex formation.
Joanna Rejek, Leszek Rycerz, Ewa Ingier-Stocka, Marcelle Gaune-Escard, J. Chem. Eng. Data 2010, 55, 1871–1875 1871

B3242 – Maps of Fe–Al phases formation kinetics parameters during isothermal sintering

The influence of technological parameters (compaction pressure and sintering temperature) on Fe–Al phase formation was investigated. The kinetics of phase transformation preceding and during an SHS reaction was studied in isothermal conditions by DSC using the JMA (Johnson–Mehl–Avrami) model. This model allowed us to determine basic kinetic parameters, including the Avrami exponent, which characterises the rate and manner of particular phase nucleation. The activation energy (Ea) of particular phase formation was determined by the Kissinger method. XRD analysis and SEM observations of sintered material showed that not only Fe2Al5 phase and low-aluminium solid solution in iron but also aluminium-rich FeAl2 and FeAl3 phases are formed during the sintering of an FeAl50 elementary powder mixture in isothermal conditions with an SHS reaction. The above conclusions were confirmed by iron-based solid solution lattice parameter studies and microhardness measurements
Ewelina Pochec, Stanis?aw Józwiak, Krzysztof Karczewski, Zbigniew Bojar, Thermochimica Acta 545 (2012) 14– 19

B3241 – Combined ab initio, experimental, and CALPHAD approach for an improved thermodynamic evaluation of the Mg–Si system

A new thermodynamic evaluation of the well-known Mg–Si system is presented with the aim to resolve persistent uncertainties in the Gibbs energy of its only compound, Mg2Si. For this purpose the heat capacity and enthalpy of melting of Mg2Si were measured by differential scanning calorimetry. Using finite temperature density functional theory and the quasiharmonic approximation, thermodynamic properties of Mg2Si were additionally calculated up to and above its melting temperature. Using these new data, in particular the heat capacity, the Mg–Si system was evaluated thermodynamically with the CALPHAD method leading to a thermodynamic description of the system within narrow bounds. In contrast to several previous evaluations there is no problem with an inverted miscibility gap in the liquid. Although present enthalpy of melting data turned out to be inconsistent with other data in this system, the new evaluation accurately describes all other available data in this system. In particular the Gibbs energy of Mg2Si can now be considered reliably described.
Michael Schick, Bengt Hallstedt, Albert Glensk, Blazej Grabowski, Tilmann Hickel, Milan Hampl, Joachim Gröbner, Jörg Neugebauer, Rainer Schmid-Fetzer, CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry 37 (2012) 77–86

B3235 – Influence of mechanical alloying conditions on amorphous phase formation in Fe67B33

Mechanical alloying of Fe67B33 mixture was carried out in a planetary ball mill. Variable milling parameters were a balls size, a milling atmosphere (Ar, He) and a filling ratio. Powders were characterized by X-ray diffraction analysis, electron scanning microscopy (SEM) and differential scanning calorimetry (DSC). It was found that balls temperature strongly affects the amorphous phase quantity: the use of atmosphere with higher thermal conductivity (He) and small balls noticeably increases the amorphous phase output. It was revealed by SEM that considerable part of boron particles survives in the course of the milling and their presence can be responsible for a broad exothermic effect on the DSC curves. The maximal volume fraction of amorphous phase was about 77% and its composition was evaluated as 20/22 at.% B.
T.A. Sviridova, E.V. Shelekhov, V.I. Bazilyan, T.R. Chueva, N.V. Shvyndina, N.P. Dyakonova, Journal of Alloys and Compounds (2012)

B3208 – Half-Heusler phase related structural perturbations near stoichiometric composition FeZnSb

Half-Heusler phases XYZ (Pearson symbol cF12) are chemically versatile and rich in physical properties. The half-Heusler phase in the Fe–Zn–Sb ternary system was reported in the year 2000. In this work, two new ternary phases are identified in the vicinity of the equiatomic composition FeZnSb in the same system: Fe1?xZnSb (tetragonal, space group P4/nmm, Pearson symbol tP6??, Z=2: a=4.1113(6) Å, c=6.0127(12) Å for x=0.08 (1), and a=4.1274(6) Å, c=6.0068(12) Å for x=0.12 (2)); and Fe7.87Zn6.72Sb8 (Fe0.98Zn0.84Sb) (3) (cubic, space group Fm-3m, Pearson symbol cF96??, Z=4, a=11.690(13) Å). 1 and 2 crystallize in the PbFCl-type structure, and 3 adopts a unique 2×2×2 supercell of a normal half-Heusler structure. The structures of both the tetragonal and cubic phases can be described as assemblies of half-Heusler structure related subunits. Electrical resistivity measurement on the pure sample of 2 shows it has metallic-like behavior, and its thermal and magnetic properties are also characterized.
Ding-Bang Xiong, Yufeng Zhao, Journal of Solid State Chemistry 184 (2011) 1159–1164

B3207 – Effects of short-time heat treatment and subsequent chemical surface treatment on the mechanical properties, low-cycle fatigue behavior and corrosion resistance of a Ni–Ti (50.9 at.% Ni) biomedical alloy wire used for the manufacture of stents

Cold-drawn and straight-annealed NiTi wires (50.9% Ni) with a tensile strength of 1650 MPa were subjected to heat treatments at 450, 510 and 600 °C for 10 min in air to simulate the shape-setting process in the manufacture of stents. Afterwards, the wires were chemically etched in acidic baths containing HF, HNO3 and H2O, followed by boiling in water. Variations in the internal structure, surface state and chemistry and transformation behavior of the wires due to these treatments were examined in detail by scanning and transmission electron microscopy, energy dispersion spectrometry, glow discharge spectrometry, X-ray photoelectron spectroscopy and differential scanning calorimetry. Mechanical properties were determined by tensile tests, and low-cycle fatigue behavior was measured by bend-type cyclic loading tests. Corrosion behavior was assessed by immersion tests and potentiodynamic measurements. A high tensile strength of the wire was shown to be attributable to a very fine-grained structure and work hardening. Heat treatment at 450–510 °C/10 min did not significantly affect the tensile strength of the wire. At 600 °C/10 min, the strength decreased by about 600 MPa due to recrystallization. The transformation temperatures first slightly increased after heat treatment at 450 °C and then reduced after treatments at higher temperatures due to changes in the composition of the B2 phase. The fatigue life was observed to prolong with both heat treatment and chemical etching. In contrast, the corrosion resistance worsened with heat treatment, but it improved significantly upon chemical etching. The observed behaviors are discussed in relation to the structural and chemical characteristics of the wires subjected to various treatment regimes.
D. Vojtech,?, M. Voderová, J. Kubásek, P. Novák, P. Sedáa A. Michalcová, J. Fojt, J. Hanus, O. Mestek, Materials Science and Engineering A 528 (2011) 1864–1876

B3198 – Lead-free soldering: Investigation of the Cu–Sn–Sb system along the Sn:Sb = 1:1 isopleth

The Cu–Sn–Sb system has been experimentally investigated by a combination of optical microscopy, differential scanning calorimetry (DSC) and electron probe microanalysis (EPMA). DSC was used to identify a total number of five invariant ternary reactions and the Sn:Sb = 1:1 isopleth section up to 65 at.% Cu was constructed by combining the DSC data with the EPMA analyses of annealed alloys and literature information. The composition limits of the binary phases were detected.
Y. Yuan, G. Borzone, G. Zanicchi, S. Delsante, Journal of Alloys and Compounds 509 (2011) 1595–1600

B3192 – Development and characterization of advanced 9Cr ferritic/martensitic steels for fission and fusion reactors

This paper presents the results on the physical metallurgy studies in 9Cr Oxide Dispersion Strengthened (ODS) and Reduced Activation Ferritic/Martensitic (RAFM) steels. Yttria strengthened ODS alloy was synthesized through several stages, like mechanical milling of alloy powders and yttria, canning and consolidation by hot extrusion. During characterization of the ODS alloy, it was observed that yttria particles possessed an affinity for Ti, a small amount of which was also helpful in refining the dispersoid particles containing mixed Y and Ti oxides. The particle size and their distribution in the ferrite matrix, were studied using Analytical and High Resolution Electron Microscopy at various stages. The results showed a distribution of Y2O3 particles predominantly in the size range of 5–20 nm. A Reduced Activation Ferritic/Martensitic steel has also been developed with the replacement of Mo and Nb by W and Ta with strict control on the tramp and trace elements (Mo, Nb, B, Cu, Ni, Al, Co, Ti). The transformation temperatures (Ac1, Ac3 and Ms) for this steel have been determined and the transformation behavior of the high temperature austenite phase has been studied. The complete phase domain diagram has been generated which is required for optimization of the processing and fabrication schedules for the steel.
S. Saroja, A. Dasgupta, R. Divakar, S. Raju, E. Mohandas, M. Vijayalakshmi, K. Bhanu Sankara Rao, Baldev Raj, Journal of Nuclear Materials 409 (2011) 131–139

B3190 – Characteristic free volumes of bulk metallic glasses: Measurement and their correlation with glass-forming ability

A convenient method is proposed for the measurement of the characteristic free volumes, viz., the amount of excess free volume annihilation in structural relaxation Vf-sr and the amount of new free volume production in glass transition Vf-gt of bulk metallic glasses (BMGs) by thermal dilation (DIL) test. Through the DIL tests, the characteristic free volumes are found to be sensitive to the change of glass forming ability (GFA). The Pd40Cu30Ni10P20 BMG has a quite small Vf-sr. For a series of Fe–Cr–Mo–C–B–(Er) BMGs, Fe48Cr15Mo14C15B6Er2 with the largest GFA is identified to have the largest Vf-gt and smallest Vf-sr. The correlation between Vf-sr and the squares of critical diameters of these iron-based BMGs can be fitted as a negative exponential function with high accuracy.
Qiang Hu, Xie-Rong Zeng, M. W. Fu, Journal of Applied Physics 109, 053520 (2011)

B3188 – Effect of (Mo, W) substitution for Nb on glass forming ability and magnetic properties of Fe–Co-based bulk amorphous alloys fabricated by centrifugal casting

In this study, effects of simultaneous Mo and W substitution for Nb additions on the stability and magnetic properties of Fe–Co-based bulk metallic glass (BMG) alloys fabricated by centrifugal casting are investigated. The saturation magnetization (Js) and coercivity (Hc) for the as-cast Fe36Co36B19.2Si4.8X4 (X = Nb or Mo0.5W0.5) BMG alloys and melt-spun Fe36Co36B19.2Si4.8Mo2W2 were in the range of 1.02–1.57 T and 11.13–1685 A/m, respectively. The Fe36Co36B19.2Si4.8X4 (X = Nb or Mo0.5W0.5) BMG alloys in the shape of wedge with the maximum thickness of 1.5–2 mm were obtained successfully by means of conventional centrifugal casting. Replacing Nb with Mo0.5W0.5 deteriorates magnetic properties in bulk form and reduces the GFA of the alloy due to promoting the precipitation of non-magnetic compounds, while it results in good soft magnetic properties in melt-spun ribbon form.
Ilker Kucuk, Muratahan Aykol, Orhan Uzun, Mehmet Yildirim, Mehmet Kabaer, Nagehan Duman, Fikret Yilmaz, Kadir Erturk, M. Vedat Akdeniz, Amdulla O. Mekhrabov, Journal of Alloys and Compounds 509 (2011) 2334–2337

B3187 – The reactive stabilization of Al–Zn foams using a powder metallurgy approach

The Al–Zn binary system was chosen in order to study the possibility of generating a reactive foam system within the semi-solid region. The idea is to create foam at lower temperatures than the melting point of pure aluminum using a transient liquid phase that softens the matrix prior to bulk expansion. This minimizes crack formation, collapse, drainage and deformation generated during processing. The Al–Zn foams were fabricated via the powder metallurgy route by hot compaction and subsequently foamed using TiH2 as a blowing agent. The investigated systems consist of low, medium and high concentrations of Zn (10 wt%, 33 wt% and 50 wt%) in an Al based matrix containing 0.8 wt% TiH2. High temperature in situ confocal microscopy was used to study the formation of the transient liquid phase of the compacted elemental powders. As the percentage of Zn was increased, the liquidus temperature of the melt was lowered along with an increase in the volume of transient liquid phase. This reduces the mismatch between the hydrogen release temperature of the blowing agent and the liquidus temperature of the melt, thus increasing foaming stability. Reasonable foam structures near 300 vol% expansion and fair pore distributions were achieved at low concentrations of Zn (10 wt%) only above the alloy liquidus point. The mechanical compressive strength properties of the alloyed foam systems were also assessed.
M. Lafrance, M. Isac, F. Jalilian, K.E. Waters, R.A.L. Drew, Materials Science and Engineering A 528 (2011) 6497– 6503

B3185 – The characterization of structure, thermal stability and magnetic properties of Fe–Co–B–Si–Nb bulk amorphous and nanocrystalline alloys

Recently bulk amorphous alloys have attracted great attention due to their excellent magnetic properties. The glass-forming ability of bulk amorphous alloys depends on the temperature difference (?Tx) between glass transition temperature (Tg) and crystallization temperature (Tx). The increase of ?Tx causes a decrease of the critical cooling rate (Vc) and growth of the maximum casting thickness of bulk amorphous alloys. The aim of the present paper is to characterize the structure, the thermal stability and magnetic properties of Fe36Co36B19Si5Nb4 bulk amorphous alloys using XRD, Mössbauer spectroscopy, DSC and VSM methods. Additionally the magnetic permeability ?i (at force H ? 0.5 A/m and frequency f ? 1 kHz) and the intensity of disaccommodation of magnetic permeability ??/?(t1) (?? = ?(t1 = 30 s) ? ?(t2 = 1800 s)), have been measured, where ? is the initial magnetic permeability measured at time t after demagnetisation, the Curie temperature TC and coercive force Hc of rods are also determined with the use of a magnetic balance and coercivemeter, respectively. Fe–Co–B–Si–Nb bulk amorphous alloys were produced by pressure die casting with the maximum diameters of 1 mm, 2 mm and 3 mm. The glass transition temperature (Tg) of studied amorphous alloys increases from 807 K for a rod with a diameter of 1 mm to 811 K concerning a sample with a diameter of 3 mm. The crystallization temperature (Tx) has the value of 838 K and 839 K for rods with the diameters of 1 mm and 3 mm, respectively. The supercooled liquid region (?Tx = Tx ? Tg) has the value of about 30 K. These values are presumed to be the origin for the achievement of a good glass-forming ability of the Fe–Co–B–Si–Nb bulk amorphous alloy. The investigated amorphous alloys in the form of rods have good soft magnetic properties (e.g. Ms = 1.18–1.24 T). The changes of crystallization temperatures and magnetic properties as a function of the diameter of the rods (time of solidification) have been stated.
S. Lesz, R. Babilas, M. Nabia?ek, M. Szota, M. Dospia?, R. Nowosielski, Journal of Alloys and Compounds 509S (2011) S197–S201

B3181 – Rapid solidification and phase stability evaluation of Ti–Si–B alloys

Ti-rich Ti–Si–B alloys can be considered for structural applications at high temperatures (max. 700 °C), however, phase equilibria data is reported only for T = 1250 °C. Thus, in this work the phase stability of this system has been evaluated at 700 °C. In order to attain equilibrium conditions in shorter time, rapid solidified samples have been prepared and carefully characterized. The microstructural characterization of the produced materials were based on X-ray diffraction (XRD), scanning electron microscopy (SEM-BSE), high resolution transmission electron microscopy (HRTEM), High Temperature X-ray diffraction with Synchrotron radiation (XRDSR) and Differential Scanning Calorimetry (DSC). Amorphous and amorphous with embedded nanocrystals have been observed after rapid solidification from specific alloy compositions. The values of the crystallization temperature (Tx) of the alloys were in the 509–647 °C temperature range. After Differential Scanning Calorimetry and High Temperature X-ray Diffraction with Synchrotron radiation, the alloys showed crystalline and basically formed by two or three of the following phases: ?Ti, Ti6Si2B; Ti5Si3; Ti3Si and TiB. It has been shown the stability of the Ti3Si and Ti6Si2B phases at 700 °C and the proposition of an isothermal section at this temperature.
K.C.G. Candioto, C.A. Nunes, G.C. Coelho, P.A. Suzuki, S.B. Gabriel, Journal of Alloys and Compounds 509 (2011) 5263–5268

B3180 – Fe–Al phase formation around SHS reactions under isothermal conditions

This study investigates the phenomena preceding and accompanying the SHS reaction between Fe and Al elemental powders during sintering. SEM and XRD analysis were used to observe the mechanisms of formation of Fe–Al intermetallic phases. The analysis of sintered material just before the SHS reaction demonstrates that in addition to the well-known Fe2Al5 phase and the low-aluminum solid solution of iron, the high-aluminum phases FeAl2 and FeAl3 are formed. The kinetics of phase transformations under isothermal conditions were investigated by DSC using the JMA (Johnson–Mehl–Avrami) model. This approach allowed us to calculate Avrami coefficients, which characterize the speed and the manner of particular phase transformations.
Ewelina Pochec, Stanis?aw Józwiak, Krzysztof Karczewski, Zbigniew Bojar, Journal of Alloys and Compounds 509 (2011) 1124–1128

B3178 – Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

Three-point bending experiments were performed on as-cast and annealed samples of Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit105) bulk metallic glasses over a wide range of temperatures varying from room temperature (293 K) to liquid nitrogen temperature (77 K). The results demonstrated that the free volume decrease due to annealing and/or cryogenic temperature can reduce the propensity for the formation of multiple shear bands and hence deteriorate plastic deformation ability. We clearly observed a sharp ductile-to-brittle transition (DBT), across which microscopic fracture feature transfers from micro-scale vein patterns to nano-scale periodic corrugations. Macroscopically, the corresponding fracture mode changes from ductile shear fracture to brittle tensile fracture. The shear transformation zone volume, taking into account free volume, temperature and strain rate, is proposed to quantitatively characterize the DBT behavior in fracture of metallic glasses.
F. Jiang, M.Q. Jiang, H.F. Wang, Y.L. Zhao, L. He, J. Sun, Acta Materialia 59 (2011) 2057–2068

B3172 – Effect of annealing treatment on microstructure and properties of high-entropy FeCoNiCrCu0.5 alloy

As-cast FeCoNiCuAl high entropy alloys were annealed at various temperatures for a given time. The microstructure and mechanical properties of the annealed FeCoNiCuAl high entropy alloys were investigated using optical microscopy, scanning electron microscopy, X-ray diffraction, compressive and hardness tests. It has been found that the FeCoNiCuAl has high thermal stability. A needle-like Cu-rich FCC phase has been precipitated from the BCC dendrite region when the annealing temperature is higher than 973 K. The higher temperature treatment greatly enhances the plasticity of the alloys, and reduces the hardness of the alloys. The annealing induced change in microstructure and properties could be attributed to a solid phase transformation, which consists of the dissolution of the FCC interdendrite phase into the matrix and the concomitant precipitation of the needle-like shape FCC phase from dendrite region.
Chun-Ming Lin, Hsien-Lung Tsai, Materials Chemistry and Physics 128 (2011) 50–56

B3171 – The role of heat treatment on microstructure and mechanical properties of Ti–13Zr–13Nb alloy for biomedical load bearing applications

The effect of heat treatment on microstructure and mechanical properties of a ferritic heat-resistant steel, 2.25Cr–1Mo, was investigated. The characteristics of carbides, i.e., size, morphology, distribution, and composition, in different stages of heat treatment were examined by using transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). As the heat treatment proceeded from normalizing and tempering (NT, the delivery state), simulated post-welding heat treatment (PWHT), to step cooling (SC), the carbides evolved from M3C, Mo2C to M7C3, M23C6. The uniformly dispersed carbides, e.g., Mo2C, M7C3, and M23C6, are responsible for the excellent mechanical properties and creep resistance of the steel. The result demonstrates that the coarsening of carbides deteriorates impact toughness and the morphology, crystal structure, and chemical composition of carbides are also important influencing factors.
P. Majumdar, S.B. Singh, M. Chakraborty, Journal of the Mechanical Behavior of Biomedical Materials 4 (2011) 1132-1144

B3170 – Experimental characterization of plastic flow initiation in a bulk metallic glass via intermittent compression test

Intermittently plastic compression tests of the Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass were performed under a geometrically constrained condition at different cross-head displacement rates. A flow stress-overshoot phenomenon was observed during the macroscopically plastic deformation. It was found that there is a close correlation between the stress-overshoot intensity and the spatial density of shear bands. The stress-overshoot intensity can be used as a parameter to characterize the ability of plastic flow initiation caused by the spatial nucleation of shear bands in the bulk metallic glass. The micromechanisms of shear band multiplication were discussed.
Z.H. Han, X.P. Li, L. He, W. Chen, F. Jiang, J. Sun, Intermetallics 19 (2011) 942-946

B3167 – Effect of cooling rate on solidification of Al-Ni alloys

Particles of Al-Ni alloys with different compositions (Al–50 wt-% Ni and Al–36 wt-% Ni) were produced using a drop tube-impulse system, known as Impulse Atomization. The microstructure of these rapidly solidified particles was compared with those solidified in a DSC at low cooling rates (0.083 and 0.33 K/sec). Also, the microstructure of the sample solidified in microgravity on-board of the TEXUS 44 sounding rocket was analyzed. Neutron diffraction was used to investigate the phases formed during different solidification processes. From SEM micrographs and neutron diffraction it was found that the inner parts of the TEXUS sample and the sample that was cooled at 0.083 K/sec contain almost no eutectic structure. The outer rim of the TEXUS sample showed the highest amount of Al3Ni and lowest amount of Al3Ni2 Increasing the cooling rate from 0.083 to 0.33 K/sec increased the Al3Ni/Al3Ni2 ratio. Opposite trend was observed in the impulse-atomized particles, where increasing the cooling rate decreased the Al3Ni/Al3Ni2 ratio.
A. Ilbagi, P. Delshad Khatibi, H. Henein, R. Lengsdorf, D. M. Herlach, Journal of Physics: Conference Series 327 (2011) 012010

B3166 – Optimization of composition and heat treatment design of Mg–Sn–Zn alloys via the CALPHAD method

This work is focused on the application of the calculation of phase diagrams method for alloy and heat treatment design. We analyzed the influence of Zn content on the precipitation of Mg2Sn in Mg–Sn–Zn alloys. A comparison with previous studies in the Mg–Sn–Zn system was made according to the published results and computational thermochemistry simulations. The phase evolution in the Mg–Sn–Zn system was evaluated for the different compositions, and the simulations were used for precise alloy and heat treatment design. The composition of the ternary alloy was set as Mg–8wt%Sn–1.25wt%Zn. The Sn and Zn content was designed and confirmed to be within the ?-Mg solubility limit at the solution treatment temperature. The addition of Zn and the heat treatment applied resulted in the enhancement and refinement of the Mg2Sn precipitation. Three Vickers micro-hardness maxima were detected: precipitation of metastable Mg–Zn phases, heterogeneous precipitation of Mg2Sn on the Mg–Zn precipitates, and Mg2Sn precipitation in the ?-Mg matrix. The CT simulations were found to be a valuable alloy design tool.
S. Avraham, A. Katsman, M. Bamberger, J Mater Sci (2011) 46:6941–6951

B3161 – The effect of Si content on the martensitic transformation temperature of Ni55:5Fe18Ga26.5-xSix alloys

This paper investigates the effects of substitution of Si for Ga on the martensitic transformation behaviours in Ni-Fe-Ga alloys by using optical metallographic microscope and differential scanning calorimetry (DSC) methods. The structure type of Ni55.5Fe18Ga26.5?xSix alloys is determined by x-ray diffraction (XRD), and the XRD patterns show the microstructure of Ni—Fe—Ga—Si alloys transformed from body-centred tetragonal martensite (with Si content x = 0) to body-centred cubic austenite (with x = 2) at room temperature. The martensitic transformation temperatures of the Ni55.5Fe18Ga26.5?xSix alloys decrease almost linearly with increasing Si content in the Si content range of x ? 3. Thermal treatment also plays an important role on martensitic transformation temperatures in the Ni-Fe-Ga-Si alloy. The valence electronic concentrations, size factor, L21 degree of order and strength of parent phase influence the martensitic transformation temperatures of the Ni-Fe-Ga-Si alloys. An understanding of the relationship between martensitic transformation temperatures and Si content will be significant for designing an appropriate Ni-Fe-Ga-Si alloy for a specific application at a given temperature.
Shen Hua-Hai, Yu Hua-Jun, Fu Hao, Guo Yuan-Jun, Fu Yong-Qing, Zu Xiao-Tao, Chin. Phys. B Vol. 20, No. 4 (2011) 046102

B3157 – Internal friction, dilatometric and calorimetric study of anelasticity in Fe–13 at.%Ga and Fe–8 at.% Al–3 at.% Ga alloys

This paper investigates the structural transitions associated with different cooling rates from a high temperature disordered state and the effect of substitution of Ga atoms by Al atoms in Fe–Ga binary alloys on the ordering processes. Two iron-based low carbon (about 0.04 at.% C) alloys Fe–13 at.% Ga and Fe–8 at.% Al–3 at.% Ga are studied. Internal friction, dilatometric and calorimetric tests are carried out to check ordering in these alloys and contribution of structural defects to relaxation spectrum. Several thermally activated internal friction peaks have been observed and their activation parameters evaluated by means of temperature and frequency dependent internal friction tests using forced vibration. For most of these peaks physical mechanisms are proposed. Apart from these thermally activated relaxation peaks, a structural, frequency independent relaxation takes place at 250–300 °C. Dilatometric and DSC curves show the appearance of a contraction effect in the same temperature range. This effect was studied in alloys cooled down with different cooling rates. We believe that the frequency independent internal friction peak (denoted as the P3 peak in this paper) and peaks at dilatometric and DSC curves are controlled by the same structural mechanism and therefore the activation energy for this anelastic mechanism is derived from DSC data.
I.S. Golovin, Z. Belamri, D. Hamana, Journal of Alloys and Compounds 509 (2011) 8165– 8170

B3155 – Microstructure and magnetocaloric effects in partially amorphous Gd55Co15Al30?xSix alloys

In order to clarify the phase components and further improve the glass-forming ability of Gd55Co15Al30 alloy, substitution of Al with Si was adopted. Although the X-ray powder diffraction experiment indicated an amorphous structure of the Gd55Co15Al30-xSix (x = 1, 2, 3) alloys, precipitation of crystalline Gd2Al phase was evident from the energy-dispersive spectroscopy, selected-area diffraction, and magnetization measurements. The magnetocaloric effect of Si substituted alloys is lower than that of Gd52.5Co16.5Al31 alloy with a similar composition and full amorphous structure, which is ascribed to the presence of antiferromagnetic Gd2Al phase whose magnetic entropy change is lower
H. Fu, M. Zou, Q. Cao, V.K. Pecharsky, K.A. Gschneidner Jr, L.S. Chumbley, Materials Science and Engineering A 528 (2011) 5219–5222

B3153 – Solidification behavior, glass forming ability and thermal characteristics of soft magnetic Fe-Co-B-Si-Nb-Cu bulk amorphous alloys

The effect of varying Cu content on the bulk glass forming ability (GFA) of (Fe0.36Co0.36B0.192Si0.048Nb0.04)100?XCuX alloys (X = 0, 0.5, 0.75 and 1.0) is revealed by investigating the thermal behaviors and phase competitions upon solidification. The changes in GFA are interpreted in terms of suppression of consecutive solidification reactions via microstructural and thermal features. Instead of the type of the primary crystallization product originating from the prevalent atomic order in the glass or supercooled liquid, precipitation of faceted binary and higher-order pro-eutectic compounds such as (Fe,Co)2B and (Fe,Co)NbB from the alloy melt and resulting skewed eutectic coupled zone are correlated with the observed GFA. With the employed centrifugal casting method, the (Fe0.36Co0.36B0.192Si0.048Nb0.04)99.25Cu0.75 alloy shows the largest critical thickness of 3 mm and the best soft magnetic properties such as 1.58 T saturation magnetization intensity and 11.7 A/m coercivity after annealing.
Muratahan Aykol, M. Vedat Akdeniz, Amdulla O. Mekhrabov, Intermetallics 19 (2011) 1330-1337

B3146 – Loading rate dependency of maximum nanoindentation depth in nano-grained NiTi shape memory alloy

We examined the effect of loading rate on maximum nanoindentation depth for nano-grained superelastic NiTi shape memory alloy during stress-induced phase transformation. The depth decreases significantly with increasing loading rate. It is argued that the observed rate dependency is attributed to the release and transfer of latent heat during indentation and the temperature dependence of the material's transition stress. Dimensional analysis further shows that the depth is mainly governed by the normalized average stress in the phase transition zone and the ratio of heat conduction time over loading time. Experimental results support the rationale.
Abbas Amini, Yongjun He, Qingping Sun, Materials Letters 65 (2011) 464–466

B3136 – The quasicrystalline phase formation in Al–Cu–Cr alloys produced by mechanical alloying

Almost single-phase decagonal quasicrystal with periodicity of 1.26 nm along 10-fold axis was produced in Al69Cu21Cr10 and Al72.5Cu16.5Cr11 alloys using combination of mechanical alloying (MA) and subsequent annealing. Phase transformations of as-milled powders depending on annealing temperature in the range of 200–800 °C are examined. Since the transformations can be explained based on kinetic and thermodynamic reasons it seems that applied technique (short preliminary MA followed by the annealing) permits to produce the equilibrium phases rather than metastable ones.
T.A. Sviridova, A.P. Shevchukov, E.V. Shelekhov, D.L. Diakonov, V.V. Tcherdyntsev, S.D. Kaloshkin, Journal of Alloys and Compounds 509S (2011) S299–S303

B3134 – Influence of superheat before quench on the structure and stability of NiP metallic glasses studied by neutron scattering techniques

The temperature dependent structure of Ni81P19 metallic glasses, rapidly quenched from melts which have undergone different heat treatments, has been investigated by small angle neutron scattering and neutron diffraction. All samples contain in the as-quenched state particles or clusters of a very wide range of sizes. These are amorphous regions of different compositions in a large composition range and/or crystallites of another Ni composition than the matrix, such as Ni3P, Ni5P2 or Ni12P5, or even “voids”. The results can be interpreted within the concept of a heterogeneous structure existing in eutectic melts in a certain temperature range. Comparison is made with results from the literature on samples from the same ribbons investigated by calorimetry as well as by fractography and Weibull analysis of mechanical properties.
M. Calvo-Dahlborg, U. Dahlborg, J.M. Ruppert, Journal of Non-Crystalline Solids 357 (2011) 798–808

B3118 – Investigation of phase transformations in ductile cast iron of differential scanning calorimetry

The effect of heating rate on phase transformations to austenite range in ductile cast iron of the EN-GJS-450-10 grade was investigated. For studies of phase transformations, the technique of differential scanning calorimetry (DSC) was used. Micro structure was examined by optical microscopy. The calorimetric examinations have proved that on heating three transformations occur in this grade of ductile iron, viz. magnetic transformation at the Curie temperature, pearlite?austenite transformation and ferrite?austenite transformation. An increase in the heating rate shifts the pearlite?austenite and ferrite?austenite transformations to higher temperature range. At the heating rate of 5 and 15 °C min?1, local extrema have been observed to occur: for pearlite?austenite transformation at 784 °C and 795 °C, respectively, and for ferrite+ graphite ?austenite transformation at 805 °C and 821 °C, respectively. The Curie temperature of magnetic transformation was extrapolated to a value of 740 °C. Each transformation is related with a specific thermal effect. The highest value of enthalpy is accompanying the ferrite?austenite transformation, the lowest occurs in the case of pearlite?austenite transformation
R. Przeliorz, J. Pi?tkowski, IOP Conf.Series:Materials Science and Engineering 22 (2011) 012019

B3117 – Thermodynamics of ???? phase transformation and heat capacity measurements in Ti–15 at% Nb alloy

The phase stability of Ti–15 at% Nb alloy has been studied in the temperature range 466–1258 K using inverse drop calorimetry. In the annealed condition, the alloy consists of orthorhombic ??-martensite and bcc ? phases. The calorimetry experiments indicated the occurrence of two phase changes upon heating. They are (i) precipitation of hexagonal ? phase at 582±2 K followed by (ii) ???? in the temperature domain 836–985±2 K. The enthalpy change due to ? formation is small; however, the ???? phase transformation is associated with a measurable enthalpy effect of 57±3 J g?1. Since ???? phase change occurs over a temperature interval, the measured enthalpy in the transformation domain derives from two principal contributions, namely, the matrix contribution coming from untransformed ??-martensite and ? phase mix and another transformational component arising from continuous ???? phase change. Since the fractional extent of ???? transformation varies continuously with temperature the transformation enthalpy also exhibits similar temperature dependence. This aspect is modeled using Kolmogorov–Johnson–Mehl–Avrami formalism for treating the diffusional transformation kinetics. Further, the measured enthalpy variation with temperature has been subjected to standard analytical treatment to obtain a comprehensive thermodynamic description of entire ??+? region.
A. Josephine Prabha, S.Raju, B.Jeyaganesh, Arun Kumar Rai, Madhusmita Behera, M. Vijayalakshmi, G.Paneerselvam, I.Johnson, Physica B406(2011)4200–4209

B3076 – Experimental verification of hematite ingot mould heat capacity and its direct utilisation in simulation of casting process

Heat capacity of alloys (metals) is one of the crucial thermophysical parameters used for process behaviour prediction in many applications. Heat capacity is an input variable for many thermodynamical (e.g. Thermocalc, Pandat, MTData, …) and kinetic programs (e.g. IDS-Solidification analysis package, …). The dependences of heat capacity on common variables (temperature, pressure, ...) are also commonly used as the input data in software packages (e.g. ProCast, Magmasoft, ANSYS Fluent, …) that are applicable in the field of applied research for simulations of technological processes. It follows from the above that the heat capacities of materials, alloys in our case, play a very important role in the field of basic and applied research. Generally speaking, experimental data can be found in the literature, but corresponding (needed) data for the given alloy can very seldom be found or can differ from the tabulated ones. The knowledge of proper values of heat capacities of alloys at the corresponding temperature can be substantially used for addition to and thus towards the precision of the existing database and simulation software. This study presents the values of Cp measured for the hematite ingot mould and comparison of the measured data with the Cp values obtained using the software CompuTherm with respect to simulation of technological casting process
Bedrich Smetana, Monika Zaludova, Marketa Tkadleckova, Jana Dobrovska, Simona Zla, Karel Gryc, Petr Klus, Karel Michalek, Pavel Machovcak, Lenka Rehackova, J Therm Anal Calorim (2013) 112, 473–480

B3063 – Solidifying incongruently melting intermetallic phases as bulk single phases using the example of Al2Cu and Q-phase in the Al–Mg–Cu–Si system

Plane front directional solidification experiments were carried out for preparing incongruently melting intermetallic phases in the quaternary alloy system Al–Cu–Mg–Si, particularly the binary Al2Cu phase and the quaternary phase (“Q-phase”). By this method, bulk samples that consist of only a single phase are generated. Sample sections consisting of 100% single phase Al2Cu and of 95% Q-phase, respectively, were obtained. The composition of the Q-phase was measured by Energy Dispersive X-ray Spectroscopy (EDX). The measured concentrations are close to the Al3Cu2Mg9Si7 composition that has recently been predicted as most stable by ab initio calculations. A peritectic temperature of 703 °C for the reaction Q ? L + Mg2Si + (Si) was determined by differential scanning calorimetry (DSC). An optimization of the Calphad database was performed considering the measured composition and peritectic temperature. For validating the optimized database, Scheil calculations were performed and compared with the experimentally determined sequence of solidifying phases.
Andrea Löffler, Joachim Gröbner, Milan Hampl, Hannes Engelhardt, Rainer Schmid-Fetzer, Markus Rettenmayr, Journal of Alloys and Compounds 515 (2012) 123– 127

B3062 – Standard enthalpies of formation of Ce–Au congruent compounds (CeAu, CeAu2, and Ce14Au51)

The enthalpies of formation of Ce–Au congruent compounds (CeAu, CeAu2, and Ce14Au51) have been determined at 1123 K and the standard enthalpies of formation at 298 K have been deduced from the measurements of enthalpy increments of single-phase samples. The following values (kJ/mole of atoms) are reported: ?fH°1123 K (CeAu) = ?75.2 ± 1.4, ?fH°298 K (CeAu) = ?76.2 ± 1.9, ?fH°1123 K (CeAu2) = ?71.3 ± 2.0, ?fH°298 K (CeAu2) = ?70.3 ± 2.2, ?fH°1123 K (Ce14Au51) = ?55.0 ± 1.7, and ?fH°298 K (Ce14Au51) = ?53.2 ± 1.9.
A. Janghorban, M. Lomello-Tafin, T. Mazingue, J. Chem. Thermodynamics 51 (2012) 65–69

B3061 – Preparation and characterization of Fe-based bulk metallic glasses in plate form

Amorphous alloys with composition (at%) Fe48Cr15Mo14C15B6Gd2 (alloy A) and Fe48Cr15Mo14C15B6Y2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness (?13 GPa) and the Young modulus (?180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.
G.C. Lavorato, G.Fiore, A.Castellero, M.Baricco, J.A.Moya, Physica B407 (2012) 3192–3195

B3060 – Structural and magnetic properties of Fe76P5(Si0.3B0.5C0.2)19 amorphous alloy

Recently, bulk amorphous alloys were produced in the Fe–B–Si–P–C system with high glass forming ability, excellent magnetic properties and the advantage of containing no expensive glass-forming elements, such as Ga, Y, Cr or Nb, having, therefore, a good perspective of commercial applications. In the present work, the Fe76P5(Si0.3B0.5C0.2)19 amorphous alloy prepared by two quenching techniques has been studied. Amorphous ribbons of about 40 ?m thick were obtained by planar-flow casting together with cylinders having 1 and 2 mm diameter produced by copper mold injection casting. All the samples appear fully amorphous after X-ray diffraction analysis. A comprehensive set of thermal data (glass, crystallization, melting and liquidus temperatures) were obtained as well as a description of the melting and solidification processes. Mechanical microhardness tests showed that the samples have a hardness of 9.7 ± 0.3 GPa. Good soft-magnetic properties were obtained, including a high magnetization of 1.44 T and a low coercivity (4.5 A/m for ribbons and 7.5 A/m in the case of 1 mm rod samples, both in as-cast state). Thermomagnetic studies showed a Curie temperature around 665 K and the precipitation of new magnetic phases upon temperatures of 1000 K. Furthermore, the frequency dependence of magnetic losses at a fixed peak induction was studied. The results suggest the occurrence of a fine magnetic domain structure in bulk samples. The good soft magnetic properties of the bulk metallic glass obtained by copper mold casting for this particular Fe-based composition suggests possible applications in transformer cores, inductive sensors and other devices.
G.C. Lavorato, G. Fiore, P. Tiberto, M. Baricco, H. Sirkin, J.A. Moya, Journal of Alloys and Compounds 536S (2012) S319– S323

B3048 – Simulated body-fluid tests and electrochemical investigations on biocompatibility of metallic glasses

This paper presents the in-vitro and electrochemical investigations of four metallic glasses (MGs) for finding potential MG-based bio-materials. The simulation body-fluid Hanks solution is utilized for testing the corrosion resistance of MGs, and microorganisms of Escherichia coli are used in testing the bio-toxicity. In addition, a simple cyclic voltammetry method is used for rapid verification of the potential electrochemical responses. It is found that the Zr-based MG can sustain in the body-fluid, exhibiting the best corrosion resistance and electrochemical stability. The microbiologic test shows that E. coli can grow on the surface of the Zr-based metallic glass, confirming the low cell toxicity of this Zr-based MG.
C.H. Li, C.H. Huang, J.F. Chuang, H.C. Lee, M.C. Liu, X.H. Du, J.C. Huang, J.S.C. Jang, C.H. Chen, Materials Science and Engineering C 32 (2012) 2578–2582

B3041 – Evolution of precipitation during non-isothermal ageing of an Mg–Ca–Zn alloy with high Ca content

In this work, the precipitation behaviour of an Mg–Ca–Zn alloy with high content of Ca relative to Zn was studied. Differential scanning calorimetry (DSC) was combined with transmission electron microscopy (TEM) and hardness measurement to examine the precipitate evolution in this alloy. A non-isothermal age-hardening heat treatment was performed to allow for a direct comparison to DSC results. Thermodynamic analysis aided in identifying ageing heat treatments to further de-convolute the overlapping DSC data. Results suggested the precipitation events followed sequential evolution towards the formation of two types of equilibrium phases (i.e. Mg2Ca and Mg6Ca2Zn3). Early stage decomposition of the solid solution had no observable effect on hardness, but was followed by the formation of hardening GP zones. Fine basal plates, as well as large coarse basal plates of Mg2Ca-type formed on further ageing. Contrast due to fine unidentified nanoscale precipitates was also observed in the over-aged state. These precipitates tended to disappear, while blocky Mg2Ca equilibrium phase precipitates formed as the heat treatment progressed to the highest temperature studied (i.e. 300 °C). However, the equilibrium Mg6Ca2Zn3phase was not observed when this final test temperature was achieved at the end of the non-isothermal heat treatment process.
Brian Langelier, Xiang Wang, Shahrzad Esmaeili, Materials Science and Engineering A 538 (2012) 246– 251

B3038 – Foaming behavior of powder metallurgical Al–Sn foams

Foaming Al by the powder metallurgy technique was investigated with Sn additions (<5 wt.%). The low melting point of Sn and its immiscibility with Al creates integrity of the powder mixture during hot compaction and foaming. Furthermore, it decreases the surface tension of Al, reducing pore coalescence. Different alloying compositions and pressing and foaming parameters were evaluated. The materials were characterized using differential scanning calorimetry and thermodynamic simulation. Foam expansion and pore shape were studied by the construction of expansion maps and image analysis on foam cross-sections. It was established that, with Sn additions, not only is foaming possible at lower temperatures, but also the Sn stabilizes the foam, preventing collapse. The number of pores and sphericity values increased with increasing Sn concentrations. Optimized process parameters leading to an expansion of 375% for up to 10 min were achieved with 2–3 wt.% Sn additions, hot pressing at 300 C followed by foaming at 725 C.
Lydia Y. Aguirre-Perales, In-Ho Jung, Robin A.L. Drew, Acta Materialia 60 (2012) 759–769

B3036 – Heat treatment of twin-belt cast EN AW 7075 alloy

The potential of twin-belt cast EN AW 7075 sheet for structural sheet applications was investigated with a particular emphasis on its response to the standard industrial T6 heat treatment. The twin belt cast EN AW 7075 strip is dendritic with an ?(Al)–Mg(Zn,Cu,Al)2 eutectic and predominantly Mg2Si and Al12(Fe,Cr,Mn)3Si particles at interdendritic sites. The ?(Al)–Mg(Zn,Cu,Al)2 eutectic has largely transformed into a Mg(Zn,Cu,Al)2 precipitate-rich network during the break down pass. The coarse intermetallic particles have fragmented while the fine intragranular precipitates have coarsened upon further hot rolling to a gauge of 2 mm. The predominant restoration process during rolling at 350 °C was dynamic recovery with no evidence of recrystallization. A fraction of Mg(Zn,Cu,Al)2 was replaced with Al2CuMg. Both phases dissolved during the solution heat treatment at 470 °C while the hot band has entirely recrystallized. Subsequent ageing at 121 °C for 16 h has produced a T6 hardness of 170 HB, considerably higher than that reported for the conventionally processed counterpart (150 HB). In addition to a remarkable age hardening capacity, twin belt cast EN AW 7075 alloy has enjoyed a very high resistance to age softening as inferred from a nearly T6 hardness after the industrial T73 heat treatment with an additional ageing cycle at 160 °C.
Yucel Birol, Materials Characterization, 63 (2012) 1-8

B3028 – Correlation between thermal induced structural and magnetic transformations in Si-rich Fe73Cu1Si16B7Nb3 metal alloy

Properties of amorphous Fe73Cu1Si16B7Nb3 foil, the Si rich metal alloy, and the foils partly crystallised after annealing, were analysed structurally and magnetically in the temperature range from 4 to 1000 K. The Fe (Si) and Fe (B) structures were identified and characterised with the crystallisation temperatures: 750 and 893 K, activation energies 460 and 580 kJ/mol. The Curie temperatures for amorphous structure: 613 K and for crystalline structures: 820, 875, 920 and 980 K were determined. It was found and analysed a delay of the sample magnetisation, determined by thermomagnetometry, with respect to structural crystallisation, determined by scanning calorimetry, which was correlated with magnetic hyperfine field, determined by transmission Mössbauer spectroscopy.
Romuald Brzozowski, Marek E. Moneta, Nuclear Instruments and Methods in Physics Research B 279 (2012) 208–211

B2983 – Phase diagram and electrical conductivity of the DyBr3–RbBr binary system

Phase equilibrium in the DyBr3–RbBr binary system was established from differential scanning calorimetry measurements. This system exhibits three compounds, namely Rb3DyBr6, Rb2DyBr5, and RbDy2Br7, and two eutectics located at DyBr3 molar fraction x = 0.116 (T = 886 K) and x = 0.458 (T = 702 K), respectively. Rb3DyBr6 undergoes a solid–solid phase transition at 726 K and melts congruently at 1,059 K. Rb2DyBr5 and RbDy2Br7 melt incongruently at 737 and 748 K, respectively. The electrical conductivity of DyBr3–RbBr liquid mixtures was measured over the whole composition range. Results obtained are discussed in term of possible complex formation.
I. Chojnacka, L. Rycerz, M. Berkani, M. Gaune-Escard, J Therm Anal Calorim (2012) 108:481–488

B2979 – Synthesis and characterization of the intermetallic compound NiSbS

The results recently obtained by our group to get new thermoelectric materials belonging to the M–Pn–Ch ternary systems (M=Co, Fe, Ni; Pn=P, As, Sb, Ch=S, Se, Te) are here reported. We have considered the Ni–Sb–S ternary system, and some homogeneous samples of composition near to 1:1:1 were prepared employing a new and simple synthetic route, starting from pure elements. Scanning electronic microscopy, electron-probe microanalysis and X-ray powder diffraction were used to investigate the microstructure. The NiSbS lattice parameters were determined and the crystal structure was refined by Rietveld method. The crystal cell of NiSbS belongs to the P213 space group with a = 0.5931 nm. The thermal stability of the ternary compounds Ni–Sb–S was investigated by DSC technique. Electrical resistivity and thermoelectric power measurements at room temperature and at 77 K were performed on platelets obtained by cleavage of the bulk.
R. Carlini, G. Zanicchi, G. Borzone, N. Parodi, G. A. Costa, J Therm Anal Calorim (2012) 108, 793–797

B2953 – Calorimetric investigation of order–disorder transition in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys

Order–disorder phase transitions in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys have been investigated using differential scanning calorimetry and drop calorimetry. The differential scanning calorimetry measurements show that the transition in both these alloys are reversible in nature and the enthalpy increment measurements reveal that these transitions are first order in nature. The transition temperature of first-order phase transition in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys have been evaluated to be 884(±2) and 799(±2) K, respectively, from drop calorimetric measurements. The latent heat of first-order phase transition in Cu0.6Pd0.4 alloy were evaluated to be 31.2(±0.6) and 28.9(±0.5) J g-1, by enthalpy increment and differential scanning calorimetry measurements, respectively. Similarly, the latent heat of first-order phase transition in Cu0.85Pd0.15 alloy were evaluated to be 23.1(±0.6) and 21.3(±0.5) J g-1, by enthalpy increment and differential scanning calorimetry measurements, respectively. The solidus temperatures of Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys were found to be 1,457(±2) and 1,360 K, respectively.
S.C. Parida, N. S. Anand, Ram Avtar Jat, S. G. Kulkarni, J Therm Anal Calorim 2012

B2950 – Heat capacity of the AuZr compound obtained by high-temperature drop calorimetry

The enthalpy increments of the Zr0.50Au0.50 phase have been measured by high-temperature drop calorimetry in the temperature range 372e1245 K. From these results, heat capacities of ZrAu have been derived and two changes of the Cp values have been observed, in agreement with the existence of three crystalline forms of ZrAu. No latent heat was observed for the low-temperature (564 K) transition, whereas the enthalpy change at high temperature (841 K) was estimated at 1.55 kJ$mol 1, from enthalpy increments obtained by drop calorimetry. These results are discussed in relation to the crystal modifications already reported for the ZrAu compound
M. Lomello-Tafin, M.Y. Benarchid, C. Antion, A. Janghorban, J.M. Moreau, Intermetallics 19 (2011) 282-287

B2948 – Development of a Ti-based Alloy: Design and Experiment

We proposed the design methodology for titanium-based alloys based on a combination of literature survey, simulation, and experiment. We have selected and investigated the properties of novel Ti-Fe-Zr alloys specifi cally designed for densification via powder metallurgy techniques. Samples were produced by die compaction of mixed elemental powders with subsequent densification by sintering at 1,275°C in vacuum. Scanning electron microscopy and optical microscopy were used to examine the sintered microstructures to compliment hardness and tensile testing. The results show that density and mechanical properties increase with the iron and zirconium content. The best property combination was obtained with the addition of 5 wt.% iron and 5 wt.% zirconium when vacuum sintered at 1,275°C for 60 min
Haitham El Kadiri, Liang Wang, H. Ozkan Gulsoy, Pavan Suri, Seong Jin Park, Youssef Hammi, and Randall M. German, JOM, Vol. 61 No. 5, May 2009

B2947 – The Influence of Cr on the Solidification Behavior of Polycrystalline ?c(Ni)/?'(Ni3Al)-?(Ni3Nb) Eutectic Ni-Base Superalloys

In the current investigation, the effect of Cr on the solidification characteristics and as-cast microstructure of pseudobinary ?-? eutectic alloys based on a near-eutectic composition (Ni-5.5Al-13.5Nb at. pct) was investigated. It was found that Cr additions promote the formation of a higher volume fraction of ?-? eutectic microstructure in the interdendritic region. Increasing levels of Cr also triggered morphological changes in the c-d eutectic and the formation of ?-?'-? ternary eutectic during the last stage of solidification. A detailed characterization of the as-cast alloys also revealed that Cr additions suppressed the liquidus, solidus, and ?' precipitation temperature of these ?-?'-? eutectic alloys. A comparison of the experimental results with thermodynamic calculations using the CompuTherm Pandat database (CompuTherm LLC, Madison, WI) showed qualitative agreement.
Mengtao Xie, Randolph Helmink, Sammy Tin, Metallurgical and Materials Transactions A, Volume 43A, April 2012—1259

B2946 – Effect of Ternary Alloying Elements Addition on the Order-Disorder Transformation Temperatures of B2-Type Ordered Fe-Al-X Intermetallics

The effect of alloying element additions on B2MA2 order-disorder phase transformation temperatures of B2-type ordered Fe0.5(Al1ÿnXn)0.5 intermetallics (X = Cr, Ni, Mo, Ta, Mn, Ti, and W) that readily form single-phase solid solution for X = 1 at. pct were investigated experimentally. It was shown that the type of the ternary substitutional alloying elements have a profound effect on the variation of order-disorder transition temperature of Fe0.5(Al1ÿnXn)0.5 alloys. Based on the magnitude of partial ordering energies of the Al-X and Fe-X atomic pairs, predicted normalized transition temperatures, DT/To, were verified experimentally. Besides the normalized transition temperature, the relative partial ordering energy (RPOE) parameter, b, was also defined to estimate the extent of variation in B2?A2 order-disorder phase transformation temperatures upon ternary alloying additions. The RPOE parameter, b, takes into account both the effects of magnitude of partial ordering energies of Al-X and Fe-X atomic pairs and also the lattice site occupation preferences of X element atoms over B2-type ordered Fe-Al sublattices. The alloying elements, which are preferentially distributed Fe sublattice sites, b > 0, and owing to b >> 1, are more effective in increasing order-disorder transformation temperature in Fe-Al (B2) intermetallics. On the contrary, alloying elements having b<1 tend to decrease the transition temperature slightly relative to the binary FeAl intermetallic. The experimentally determined B2?A2 order-disorder transition temperatures are in good qualitative or semiquantitative agreement with theoretical predictions for all X ternary alloying elements. Accordingly, the present experimental results confirm the validity of the theoretical model and calculations proposed in our previous study on the B2?A2 order-disorder transition temperatures of single-phase Fe0.5(Al(1-n)Xn)0.5 intermetallics.
Mehmet Yildirim, M. Vedat Akdeniz, Amdulla O. Mekhrabov, Metallurgical and Materials Transactions A, Volume 43A, June 2012—1809

B2945 – Mechanical Properties and Crystallization Behaviors of Microstructured Co-Fe-P Amorphous Alloys

Microstructure with microsized amorphous grains is found in thick-film Co-Fe-P amorphous alloys prepared by electrodeposition. The amorphous alloys exhibit different structure, mechanical properties, and crystallization behaviors compared with those of homogeneous amorphous alloys, e.g., bulk metallic glasses. The mechanical properties of these microstructured amorphous alloys are characterized by tensile tests, dynamic mechanical analysis, and micro- and nanoindentations. Using a differential scanning calorimeter, the activation energy of the crystallization process of the microstructured amorphous alloy is measured and is found to depend on its microstructure.
Ying Shen, Xiu-Cheng Zheng, Guang-Ping Zheng, Metallurgical and Materials Transactions A, Volume 42A, January 2011—211

B2944 – A Study on the Effect of Thermal Ageing on the Specific-Heat Characteristics of 9Cr–1Mo–0.1C (mass%) Steel

The effect of thermal ageing on the heat-capacity behavior of 9Cr–1Mo–0.1C (mass%) ferritic/martensitic steel has been studied using differential scanning calorimetry (DSC) in the temperature range from 473K to 1,273K. The DSC results in the case of slow cooled, normalized and tempered, and subsequently thermally aged samples (500 h to 5,000 h at 823K (550 ?C) and 923K (650 ?C), clearly marked the presence of both magnetic and ?-ferrite+carbide ? ? -austenite phase transformations that take place successively upon heating. Furthermore, for the case of fully martensitic microstructure, an additional exothermic transformation at about 920K (647 ?C), arising from carbide precipitation is noticed. This event is characterized by a sharp drop in CP. It is found that the ?-ferrite + carbide ? ? -austenite phase transformation temperature is only mildly sensitive to microstructural details, but the enthalpy change associated with this phase transformation, and especially the change in specific heat around the transformation regime, are found to be dependent on the starting microstructure generated by thermal ageing treatment. Prolonged ageing for about 500 h to 5,000 h in the temperature range from823Kto 923K(550 ?C to 650 ?C) contributed to a decrease in heat capacity, as compared to the normalized and tempered sample. This is due to the increase in carbide volume fraction. The martensitic microstructure is found to possess the lowest room-temperature CP among different microstructures.
B. Jeyaganesh, S. Raju, S. Murugesan, E. Mohandas, M. Vijayalakshmi, Int J Thermophys (2009) 30, 619–634

B2943 – Transition of Crack from Type IV to Type II Resulting from Improved Utilization of Boron in the Modified 9Cr-1Mo Steel Weldment

The roles of boron and heat-treatment temperature in improving the type IV cracking resistance of modified 9Cr-1Mo steel weldment were studied. Two different heats of P91 steel, one without boron, designated as P91 and the other with controlled addition of boron with very low nitrogen, designated as P91B, were melted for the current study. The addition of Boron to modified 9Cr-1Mo steel has increased the resistance against softening in fine-grained heat-affected zones (FGHAZ) and intercritical heat-affected zones (ICHAZ) of the weldment. Creep rupture life of boron containing modified 9Cr-1Mo steel weldment, prepared from 1423 K (1150 °C) normalized base metal, was found to be much higher than that prepared from 1323 K (1050 °C) nor- malized base metal because of the stabilization of lath martensite by fineM23C6 precipitates. This finding is in contrast to the reduction in creep rupture life of P91 weldment prepared from 1423 K (1150 °C) normalized base metal compared with that of the weldment prepared from 1323 K (1050 °C) normalized base metal. The trace of failure path from the weld metal to ICHAZ in P91B weldment was indicative of type II failure in contrast to type IV failure outside the HAZ and base metal junction in P91 weldment, which suggested that boron strengthened the micro- structure of the HAZ, whereby the utilization of boron at a higher normalizing temperature seemed to be significantly greater than that at the lower normalizing temperature.
C.R. Das, S.K. Albert, J. Swaminathan, S. Raju, A.K. BhaduriI, B.S. Murty, Metallurgical and Materials Transactions A, Volume 43A, October 2012—3724

B2935 – Enthalpies of mixing of liquid systems for lead free soldering: CoeSbeSn

The partial and integral enthalpy of mixing of molten ternary CoeSbeSn alloys was determined performing high temperature drop calorimetry in a large compositional range at 1273 K. Measurements have been done along five sections, xSb/xSnz1:1, xSb/xSnz1:3, xSb/xSnz3:1, xCo/xSnz1:4, and xCo/xSbz1:5. Additionally, binary alloys of the constituent systems CoeSb and CoeSn were investigated at the same temperature. All the binary data were evaluated by means of a standard RedlicheKister polynomial fit whereas ternary data were fitted on the basis of an extended RedlicheKistereMuggianu model for substitutional solutions. An iso-enthalpy plot of the ternary system was constructed. In addition, the extrapolation Model of Toop was applied and compared to our data.
A. Elmahfoudi, A. Sabbar, H. Flandorfer, Intermetallics 23 (2012) 128-133

B2934 – Thermodynamic Properties of SmFeO3(s) and Sm3Fe5O12(s)

The enthalpy increments and the standard molar Gibbs energy (G) of formation of SmFeO3(s) and Sm3Fe5O12(s) have been measured using a Calvet micro-calorimeter and a solid oxide galvanic cell, respectively. A l-type transition, related to magnetic order-disorder transformation (antiferromagnetic to paramagnetic), is apparent from the heat capacity data at ~673 K for SmFeO3(s) and at ~560 K for Sm3Fe5O12(s).
S.C. Parida, K.T. Jacob, V. Venugopal, Journal of Phase Equilibria Vol. 24 No. 5 2003

B2932 – Enthalpy measurements of La2Te3O9 and La2Te4O11

Enthalpy increment measurements on La2Te3O9(s) and La2Te4O11(s) were carried out using a Calvet micro-calorimeter. The enthalpy values were analyzed using the non-linear curve fitting method. The dependence of enthalpy increments with temperature was given as: H°(T) ? H°(298.15 K) (J mol?1) = 360.70T + 0.00409T2 + 133.568 × 105/T ? 149 923 (373 < T (K) < 936) for La2Te3O9 and H°(T) ? H°(298.15 K) (J mol?1) = 331.927T + 0.0549T2 + 29.3623 × 105/T ? 114 587 (373 < T (K) < 936) for La2Te4O11.
M. Ali (Basu), S.R. Bharadwaj, D. Das, Journal of Nuclear Materials 360 (2007) 99–103

B2931 – Lead-Free Solder Materials: Experimental Enthalpies of Mixing of Liquid Ag-In-Pd-Sn Alloys

The partial and integral enthalpies of mixing of liquid Ag-In-Sn and Ag-In-Pd-Sn alloys were determined at 900 °C by a drop calorimetric technique using a Calvet-type microcalorimeter. The binary interaction parameters of Ag-In and the ternary interaction parameters of Ag-In-Pd and Ag-In-Sn were fitted based on both literature data and the authors’ measurements employing the Redlich–Kister–Muggiano model for substitutional solutions. Furthermore, it was investigated whether additional quaternary interactions have to be taken into account for the description of the enthalpy of mixing in the Ag-In-Pd-Sn system
Christoph Luef, Hans Flandorfer, Herbert Ipser, Metallurgical and Materials Transactions A, Volume 36A, May 2005—1273

B2930 – Thermodynamic Properties and Melting Behavior of Bi–Sn–Zn Alloys

The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500 C by a drop calorimetric technique using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500 C were constructed. Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well as the invariant reaction temperature of the ternary eutectic L ? (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found at 135 C.
Christoph Luef, Aloke Paul, Jiri Vizdal, Ales Kroupa, Alexander Kodentsov, Herbert Ipser, Monatshefte für Chemie 137, 381–395 (2006)

B2926 – Possibilities of heat capacity measurement of metallic systems

The paper deals with the study possibilities of heat capacities, mainly of metallic systems (alloys) on the basis of Fe (Fe-C). Possibilities of theoretical calculations dependencies of heat capacities on temperature are presented in this work in a wide temperature region. Theoretical basis of heat capacities determination using Neumann-Kopp rule is discussed. Experimental possibilities of heat capacities acquisition are determined by our experimental base. Two classical thermal analysers (2D DSC sensors) are used at our working site. The third experimental system is Setaram MHTC (Multi High Temperature Calorimeter). MHTC is equipped with unique 3D DSC sensors. Furthermore, the MHTC enables to analyse samples with substantially higher sample weight (2.5; up to 30 g respectively). It should be possible to obtain more accurate results with MHTC in comparison with classical 2D DSC sensors (max. sample weight approximately 500 mg). Various methods of heat capacities measurement and calculations are presented in the paper (continuous, stepped and DROP method, theoretical Neumann-Kopp rule). Initial results obtained at our working site are presented in this paper
Bed?ich Smetana, Monika Žaludova, Simona Zla, Jana Dobrovska, Markéta Tkadleckova, Petr Klus, Silvie Rosypalova, Metal 2012, Brno, Czech Republic

B2911 – Stability in Phase Transformation After Multiple Steps of Marforming in Ti-Rich Ni-Ti Shape Memory Alloy

Nickel-titanium (Ni-Ti) alloys are the most attractive among shape memory alloys (SMA) due to their good functionality properties coupled with high strength and ductility. The transformation temperatures in Ti-rich Ni-Ti SMA can be altered by subjecting them to suitable thermal and/or mechanical treatments to obtain martensitic transformation in one or more steps above 0 °C. The goal of the present work is to investigate the stability of phase transformation characteristics, such as, type of sequence (one, two, and multiple steps) and transformation temperatures in Ti-Rich Ni-Ti SMA (Ni-51 at.%Ti), after being subjected to an initial heat treatment at 500 °C for 30 min in air followed by multiple steps of marforming (cold rolling, 30% thickness reduction) intercalated with heat treatments at 500 °C for 30 min in air and a final heat treatment at four different temperatures (400, 450, 500, and 600 °C) for 30 min in air atmosphere. Differential scanning calorimetry (DSC) and electrical resistivity (ER) were used to identify the phase transformation sequences and the stability of transformation temperatures during initial 10 thermal cycles for each sample with distinct thermo-mechanical treatment.
Andersandos Santos Paula, Karimbi Koosappa Mahesh, and Francisco Manuel Braz Fernandes, Journal of Materials Engineering and Performance, Volume 20(4–5) July 2011—771

B2908 – Evolution of phase transformations after multiple steps of marforming in Ti-rich Ni-Ti SMA

The phase transformations associated with Shape Memory Effect (SME) can be one step, B19’ (martensite) ? B2 (austenite), or two/multiple steps which include the intermediate R phase, depending on the thermal and thermomechanical history of the alloy. The transformation temperatures are generally observed above room temperature in Ti-rich Ni-Ti alloys, while those observed in Ni-rich alloys occur below room temperature. The goal of the present work is to investigate the phase transformations evolution in Ti-Rich Ni-Ti SMA (Ni-51 at%Ti) when subjected to two distinct thermal treatments (500?C for 30 minutes in air and 800?C for 300 minutes in vacuum) and subsequently multiple steps of marforming thermomechanical treatments intercalated with thermal treatments (500?C for 30 minutes in air) and subsequent four distinct final thermal treatments (400, 450, 500 or 600?C for 30 minutes in air). Further, the stability of phase transformations in the initial ten thermal cycles of these thermomechanically treated samples is also studied. Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) were used to identify the transformation temperatures and the phases that are present after the thermomechanical treatments.
A.S. Paula, K.K. Mahesh, F.M. Braz Fernandes, Eur. Phys. J. Special Topics 158, 45–51 (2008)

B2898 – Heat capacities of polycrystalline nLiH and nLiD by differential scanning calorimetric method

The heat capacities of polycrystalline nLiH and nLiD were measured by differential scanning calorimeter in the temperature range from 125 to 800 K. The smoothed values of heat capacities were used to calculate various thermodynamic functions for nLiH and nLiD from 0 to 800 K. Isotopic effect on heat capacity of nLiH and nLiD is predominant at higher temperatures (>80 K) whereas below 80K the isotopic effect is negligible
Ram Avtar Jat, S.C. Parida, K. Krishnan, N.S. Anand, S.G. Sawant, Renu Agarwal, Ziley Singh, S.K. Aggarwal, V. Venugopal, Journal of Alloys and Compounds 505 (2010) 309–314

B2889 – Rapid Heat Treatment of Aluminum High-Pressure Diecastings

Recently, it has been demonstrated that common high-pressure diecasting (HPDC) alloys, such as those based on the Al-Si-Cu and Al-Si-Mg-(Cu) systems, may be successfully heat treated without causing surface blistering or dimensional instability. In some compositions, the capacity to exploit age hardening may allow the proof stress values to be doubled when compared to the as-cast condition. This heat treatment procedure involves the use of severely truncated solution treatment cycles conducted at lower than normal temperatures, followed by quenching and natural or artificial aging. The potential therefore exists to develop and evaluate secondary HPDC alloys designed specifically for rapid heat treatment, while still displaying high castability. This article reports results of an experimental program in which responses of various alloy compositions to age hardening have been investigated with the primary aim of further reducing the duration and cost of the heat treatment cycle while maintaining high tensile properties. Composition ranges have been established for which values of 0.2 pct proof stress exceeding 300 MPa (i.e., increases of ~100 pct above as-cast values) can be achieved using a procedure that involves a total time for solution treatment plus age hardening of only 30 minutes. This rapid aging behavior is shown to be related to precipitation of the complex Q' phase, which forms primarily when Mg contents of the alloys are above ~0.2 wt pct.
R.N. Lumley, I.J. Polmear, P.R. Curtis, Metallurgical and Materials Transactions A, Volume 40A, 1716, JULY 2009

B2868 – Differences in reactivity of oxide growth during the oxidation of Zircaloy-4 in water vapour before and after the kinetic transition

The oxidation of Zircaloy-4 by water vapour has been studied between 500 and 550 °C, the water vapour partial pressure ranging in 13–80 hPa, using isothermal and isobaric thermogravimetry, and calorimetry. During gravimetry experiments, sudden changes in temperature or water vapour pressure have also been performed. It results that the approximations of steady state and rate-limiting step are only valid before the kinetic transition. In the post-transition region, a significant influence of water vapour and hydrogen partial pressures has been found, contrarily to the kinetic behaviour before the transition (which is in this last case, in good agreement with a rate-limiting step of diffusion of oxygen vacancies). It comes out that the post-transition kinetic behaviour is definitely not the same as before the transition.
M. Tupin, M. Pijolat, F. Valdivieso, M. Soustelle, A. Frichet, P. Barberis, Journal of Nuclear Materials 317 (2003) 130–144

B2863 – The Sm–Ni system: new phases in the Sm-rich region

The Sm–Ni system on the Sm-rich side was experimentally investigated using differential scanning calorimetry with a slow scanning rate, as well as microscope and X-ray diffraction analyses. Two new phases Sm7Ni3 and Sm3Ni2 were observed and both of them form through a peritectic reaction and decompose at low temperature. The related invariant reactions and phase relations were determined. The phase diagram of the Sm–Ni system in the Sm-rich side has accordingly been modified. The results are discussed and compared with those of similar previously known systems.
Gabriella Borzone, Yuan Yuan, Simona Delsante, Nadia Parodi, Monatsh Chem (2012) 143,1299–1307

B2859 – Thermodynamic Properties of the Ni0.333Zr0.667 Alloy in Amorphous and Crystalline States

The heat capacity of the Ni0.333Zr0.667 alloy in amorphous and crystalline states is measured by adiabatic calorimetry from 13 to 326 K. The thermal behavior of the amorphous alloy is studied by differential scanning calorimetry between room temperature and 800 K. Amorphous Ni0.333Zr0.667 is found to crystallize in the range 628–686 K, with a heat evolution maximum at 655 K and an enthalpy increment ?crH= 2.91 kJ/mol. The heat capacity data are used to evaluate the thermodynamic properties of the Ni0.333Zr0.667 alloy in amorphous and crystalline states in the temperature range 15–320 K.
K. S. Gavrichev, V. E. Gorbunov, G. A. Sharpataya, A. V. Khoroshilov, A. I. Zaitsev, N. E. Zaitseva, B. M. Mogutnov, V. V. Molokanov, Inorganic Materials, Vol. 40, No. 6, 2004, pp. 610–615

B2831 – Precipitation Behavior of Fe-25 At. Pct Co-9 At. Pct Mo Investigated by In-Situ Small-Angle Neutron Scattering and Complementary Methods

The precipitation behavior of a nanoscaled intermetallic phase in a martensitic Fe-25 at. pct Co-9 at. pct Mo alloy was investigated by in-situ small-angle neutron scattering (SANS). Solution-annealed samples were heated to 700 °C using different heating rates while successively measuring the scattered intensity. The ratio R of nuclear and magnetic scattering intensity, sensitive to change in the chemical composition of the developing precipitates, was analyzed. Differential scanning calorimetry (DSC) was performed using identical heating rates to gain knowledge of the kinetics of the precipitation reaction. Complementarily, three-dimensional atom probe (3DAP) measurements were conducted to characterize the chemical composition of the precipitates. A good correlation of the evolution of R and the peaks occurring in the DSC curves was found. The onset temperature of the precipitation reaction was determined to be 420 °C.
E. Eidenberger, M. Schober, E. Stergar, H. Leitner, P. Staron, H. Clemens, Metallurgical and Materials Transactions A, Vol. 41, Number 5, May 2010

B2825 – Using Differential Scanning Calorimetry to Characterize the Precipitation Hardening Phenomena in a Cu-9Ni-6Sn Alloy

An attempt has been made to characterize the transformations in a Cu-9Ni-6Sn alloy using heat flux differential scanning calorimetry (DSC) assisted by hardness measurements. Both solution heat treatment and precipitation transformations have been studied. Different starting conditions were imposed on the material to allow a clearer understanding of the transformations involved. The precipitation from the supersaturated solid solution happens in two temperature ranges, i.e., from 200 to 400 °C and from 440 to 600 °C. In the temperature range from 400 to 440 °C, the alloy does not usually transform. Thermal cycles leading to aging and overaging were determined. The precipitation hardening conditions at 350 °C or lower for less than 600 min, or 375 °C for up to 120 min, lead to metastable precipitation. Precipitation hardening for 120 min at 400 °C or 1200 min at 350 °C results in stable precipitation and is responsible for overaging the alloy.
N. Lourenço, H. Santos, Journal of Materials Engineering and Performance, Volume 14(4) August 2005

B2824 – Effect of Hypoeutectic Boron Addition on the ? Transus of Ti-6Al-4V Alloy

In the present study, the ? transus of boron-modified Ti-6Al-4V alloy was found to be almost equivalent to that of the normal alloy, although there is a difference in interstitial element content large enough to produce significant change. Compositional analysis confirms the scavenging ability of the boride particles that are present in the microstructure toward the interstitial elements. This factor can successfully retard the ??? phase transformation locally and increase the overall ? transus of boron-added material.
Shibayan Roy, Vedavyas Tungala, Satyam Suwas, Metallurgical and Materials Transactions A, Volume 42A, September 2011—2535

B2823 – Homogenization of EN AW 6005A Alloy for Improved Extrudability

The homogenization practice for EN AW 6005A was investigated. It requires an 8-hour soaking at 853 K (580 °C) to even out the Mg and Si distribution in the aluminum matrix and to fully transform the monoclinic b-Al5FeSi plates into relatively small round ac-Al12(Fe,Mn)3Si particles with a ‘‘necklace’’ type configuration. It is predominantly the equilibrium b-Mg2Si phase that precipitates during subsequent cooling at 1000 K hÿ1 while orthogonal b¢-Mg2Si platelets are also noted starting at 500 K hÿ1. The hardness decreases with decreasing cooling rate from 41.1 ± 1 HV to 35.8 ± 0.8 HV, by 15 pct, over the range investigated. The precipitation capacity retained in homogenized samples cooled to room temperature at less than 250 K hÿ1 is reduced substantially. The solvus temperatures of these samples are below 773 K (500 °C) ensuring full solutionizing of the Mg2Si precipitates below the press exit temperatures typically employed by extruders. An 8-hour soaking at 853 K (580 °C) followed by cooling at 250 K hÿ1 is identified to be the optimum homogenization treatment as it gives a homogeneous structure with predominantly spherical-shaped ac-Al12(Fe,Mn)3Si particles and sufficiently low hardness for improved extrudability and a solvus temperature below 773 K (500 °C) to ensure adequate age-hardening capacity.
Yucel Birol, Metallurgical and Materials Transactions A, August 2012

B2822 – Influence of Severe Plastic Deformations on Secondary Phase Precipitation in a 6082 Al-Mg-Si Alloy

The role of severe plastic deformation on the second-phase stability in a 6082 Al-Mg-Si alloy was studied using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) techniques. The alloy was fully annealed prior to undergoing up to six equal channel angular pressing (ECAP) passes using route C. The Orowan strengthening mechanism was calculated on the basis of TEM inspections for the two hardening second-phase precipitates: Mg2Si and Si. The former had a major tendency to be cut and fragmented by dislocations, while in the latter, a dissolution process was induced by severe plastic deformation. Accordingly, the second-phase Si particles became progressively less effective with increasing deformation (i.e., additional ECAP passes). The increase in hardness with the ECAP passes was mostly due to the grain refining mechanism and to dislocation tangles within the newly formed grains. The expected, though if limited, contribution of second-phase hardening was prevalently accounted for by the Mg2Si particles.
M. Cabibbo, E. Evangelista, M. Vedani, Metallurgical and Materials Transactions A, Volume 36A, May 2005—1353

B2748 – On the Precipitation-Hardening Behavior of the Al-Mg-Si-Cu Alloy AA6111

The precipitation-hardening behavior of aluminum alloy AA6111 during artificial aging and the influence of prior natural aging on the aging behavior were investigated. The evolution of microstructure was studied using quantitative transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The evolution of the relative volume fraction of precipitates for the solutiontreated alloy was determined using isothermal calorimetry and a new analysis based on the DSC technique. Quantitative TEM was also used to obtain the rate of precipitation of microscopically resolvable phases during aging at 180 °C. Three types of precipitates, i.e., unresolved Guinier-Preston (GP) zones, b0, and Q9, were found to form during aging at 180 °C. The evolution of yield strength was related to the evolution of microstructure. It was found that the high hardening rate during artificial aging for the solution-treated alloy is due to the rapid precipitation of the b0 phase. Natural aging prior to artificial aging was found to decrease the rate of precipitation of b0. The slow hardening rate for the naturally aged alloy was attributed to the slower nucleation and growth of b0 phase.
S. Esmaeli, X. Wang, D.J. Lloyd, W.J. Poole, Metallurgical and Materials Transactions A, Volume 34A, March 2003—751

B2720 – Experimental study and thermodynamic assessment of ternary Mg–Zn–Ce phase relations focused on Mg-rich alloys

The Mg-rich part of the ternary Mg–Zn–Ce system was investigated by key samples to determine the solubilities, primary crystallization and invariant reactions. Ten alloys were prepared from pure elements and investigated by DTA/DSC and SEM/EDS. A consistent thermodynamic model of the ternary Mg–Zn–Ce system is developed for the first time by using the Calphad method. Phase diagram sections at constant 300 C, at constant 85 at.% Mg and the liquidus projection of the Mg–Zn–Ce ternary system were calculated and compared with all available experimental data. The thermodynamic description is reasonably well supported by experimental data, especially in the Mg-rich region.
Chen-nan Chiu, Joachim Gröbner, Artem Kozlov, Rainer Schmid-Fetzer, Intermetallics 18 (2010) 399–405

B2719 – Phase formation in Mg–Sn–Si and Mg–Sn–Si–Ca alloys

Experimental work is done and combined with the Calphad method to generate a consistent thermodynamic description of the Mg–Ca–Si–Sn quaternary system, validated for Mgrich alloys. The viability of a procedure for the selection of multicomponent key samples is demonstrated for this multicomponent system. Dedicated thermal analysis with DTA/DSC on sealed samples is performed and the microstructure of slowly solidified alloys is analyzed using SEM/EDX. The thermodynamic description and phase diagram of the ternary Mg–Si–Sn system, developed in detail also in this work, deviates significantly from a previous literature proposal. The phase formation in ternary and quaternary alloys is analyzed using the tool of thermodynamic equilibrium and Scheil calculations for the solidification paths and compared with present experimental data. The significant ternary/quaternary solid solubilities of pertinent intermetallic phases are quantitatively introduced in the quaternary Mg–Ca–Si–Sn phase diagram and validated by experimental data.
A. Kozlov, J. Gröbner, R. SchmidFetzer, Journal of Alloys and Compounds 509 (2011) 3326–3337

B2718 – Phase equilibria, thermodynamics and solidification microstructures of MgeSneCa alloys, Part 1: Experimental investigation and thermodynamic modeling of the ternary MgeSneCa system

The phase equilibria of the MgeSneCa system for the entire composition and temperature ranges have been clarified based on the Calphad method. To obtain a reliable thermodynamic description, we performed key experiments for the phase boundary data and also utilized the first-principle results of the finite-temperature properties for the binary and ternary compounds. Experimental works for the phase equilibria, which consist of thermal, crystallographic and microstructural analyses, and the thermodynamic modeling combined with finite-temperature first- principle calculations are reported. The satisfying agreements between the experimental and calculated results support the reliability of the proposed thermodynamic description. The phase diagram for overall composition and temperature ranges of the ternary system based on the thermodynamic calculations is presented. In a second study this result is applied to obtain details of the phase formation during solidification for practically important Mg-rich as-cast alloys.
A. Kozlov, M. Ohno, R. Arroyave, Z.K. Liu, R. Schmid-Fetzer, Intermetallics 16 (2008) 299e315

B2717 – Phase analysis of MgeLaeNd and MgeLaeCe alloys

The ternary solubilities and solidification details of the MgeNdeLa and MgeLaeCe systems were examined through the evaluation of two alloys from each system. Thermodynamic parameters of the two systems were optimized using the observed phase constituents and measured ternary solubilities by SEM combined with the DSC signals of the four alloys. Isothermal sections at 500 !C and solidification paths of the two systems were evaluated.
Joachim Gröbner, Milan Hampl, Rainer Schmid-Fetzer, Mark A. Easton, Suming Zhu, Mark A. Gibson, Jian-Feng Nie, Intermetallics 28 (2012) 92e101

B2716 – Phase equilibria and transformations in ternary Mg-rich Mg–Y–Zn alloys

The long-period stacking ordered structures 18R and 14H formed in Mg–Y–X (X = Zn, Cu, Ni) systems have received considerable interest over the past decade, but their thermal stability and relationships with other intermetallic phases in the Mg–Y–X systems remain to be unambiguously established. In this study, the occurrence and transformations of long-period stacking ordered structures 18R and 14H are clarified in as-cast and heat-treated Mg–Y–Zn alloys. The 18R structure is a stable equilibrium phase that forms directly from the melt whereas the 14H cannot form directly from the melt but forms in a solid-state transformation. That explains the absence of 14H in the as-cast microstructures of the alloys. These findings are embedded in the complete description of Mg–Y–Zn phase equilibria, generated by Calphad-type thermodynamic calculations and verified for a range of Mg-rich alloys by electron microscopy and thermal anal- ysis. It is found that the 18R is a stable equilibrium phase that exists in the high temperature range from 753 to 483 °C, and that the 14H is an equilibrium phase below 537 °C. In the small temperature range between 537 and 483 °C, the 18R and 14H can co-exist in equilibrium in some special alloy compositions.
J. Gröbner, A. Kozlov, X.Y. Fang, J. Geng, J.F. Nie, R. Schmid-Fetzer, Acta Materialia 60 (2012) 5948–5962

B2715 – Thermodynamic modeling of the Mg–Al–Ca system

A thermodynamic model has been developed that provides a quantitative description for a wide area of the Mg–Al–Ca system. All available experimental data plus new key experiments using differential scanning calorimetry/differential thermal analysis have been considered to create a dataset which reproduces the primary crystallizing phases, the extensive ternary solubilities of binary phases and the ternary C36 Laves phase. This enables validated thermodynamic calculations in various areas of this ternary system.
A. Janz, J. Gröbner, H. Cao, J. Zhu, Y.A. Chang, R. Schmid-Fetzer, Acta Materialia 57 (2009) 682–694

B2711 – Thermodynamic analysis of as-cast and heat-treated microstructures of Mg–Ce–Nd alloys

Alloys based on Mg–rare earth (RE) systems are of increasing technical interest in automotive powertrain applications due to their superior elevated temperature creep resistance. However, there is a deficiency in the literature of phase diagrams of multi-component RE systems that could assist alloy development and composition refinement for enhanced property optimization. The phase relationships in the Mg-rich corner of the Mg–Ce–Nd system have been investigated through the evaluation of selected compositions in the as-cast and heat-treated condition. Consistent thermodynamic CALPHAD-type assessments have also been generated for the Mg–Ce–Nd system. It is shown that this system reveals a significant degree of metastability under technologically significant solidification conditions (i.e. permanent-mould or high-pressure die casting). This is simulated in thermodynamic calculations by suppression of the RE5Mg41 phase and reasonable agreement is found with the as-cast microstructures. After heat treatment these microstructures transform, depending on the alloy composition, into phase assemblies consistent with the calculated stable equilibrium phase diagram. It is the elucidation of such metastable phase formation and the subsequent transformation from the as-cast to the heat-treated state that is a particular strength of the thermodynamic approach and which makes it a powerful tool for alloy development.
Joachim Grôbner, Artem Kozlov, Rainer Schmid-Fetzer, Mark A. Easton, Suming Zhu, Mark A. Gibson, Jian-Feng Nie, Acta Materialia 59 (2011) 613–622

B2710 – Mixing enthalpies of liquid Au–Sb–Sn alloys

Using a MHTC 96 Setaram high-temperature drop calorimeter, partial and integral enthalpies of liquid alloy mixing were determined in the ternary Au–Sb–Sn system. The alloys were investigated along three cross sections at two different temperatures: 923 and 1,078 K. Experimental data were used to find ternary interaction parameters by applying the Redlich-Kister-Muggianu model for substitutional solutions, and a full set of parameters describing the concentration dependence of the mixing enthalpy was derived. It was found that the entire system shows exothermic mixing enthalpy at the given temperature. Moreover, experimental data indicate that the mixing heat in this system is temperature independent, at least in the measured temperature range.
Dominika Jendrzejczyk-Handzlik, Krzysztof Fitzner, Monatsh Chem (2012) 143,1225–1233

B2709 – Thermodynamic Aspects of the Constitution, Grain Refining, and Solidification Enthalpies of Al-Ce-Si Alloys

The ternary Al-Ce-Si phase equilibria were investigated using X-ray diffraction (XRD) methods, metallography, scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDX) and wavelength-dispersive X-ray microanalysis, and differential thermal analysis (DTA). The focus was on the Al-rich corner and the phases in equilibrium with (Al). Key experiments were selected by preliminary thermodynamic calculations. A consistent thermodynamic description was developed using the Calphad method incorporating all experimental data. A thermodynamic assessment for the binary Ce-Si system was also performed. Two ternary phases, Ce(Si1 xAlx)2 ( 1) and AlCeSi2 ( 2), were confirmed. The phase Al2CeSi2 ( 4) was sporadically observed, but is apparently metastable. The earlier reported phase Al4Ce3Si6 could not be confirmed. In addition, the enthalpy of solidification of five Al-rich ternary alloys was measured in a differential scanning calorimetry (DSC) heat flux calorimeter. The agreement with the thermodynamic enthalpy calculations is acceptable. The fundamental intricacies involved in calculating a “latent” heat for alloys with a freezing range are pointed out. Various phase diagrams of the Al-Ce-Si system were calculated based on the thermodynamic description. They were used to quantitatively identify possible contributions to the grain refinement potential of Ce in Al-Si alloys due to the phase equilibria.
Joachim Gröbner, Djordje Mirkovic, Rainer Schmid-Fetzer, Metallurgical and Materials Transactions A, Volume 35A, November 2004—3349

B2701 – A Study on Thermal Properties and ?(hcp) ? ?(bcc) Phase Transformation Energetics in Ti–5mass% Ta–1.8mass% Nb Alloy Using Inverse Drop Calorimetry

Accurate measurements of enthalpy increment (HT ? H298.15) values have been made on a Ti–5mass% Ta–1.8mass% Nb alloy using the inverse drop calorimetry technique in the temperature range from 463K to 1457 K. The measured enthalpy increment values show a steady increase with temperature in both ?-hcp and ?-bcc solid solution regions. It is found that both the onset as well the completion of the ? ? ? phase change are demonstrated by a marked deviation of the enthalpy increment behavior from the otherwise smooth variation encountered in the respective low-temperature ?- and high-temperature ?-phase domains. The transformation start (Ts) and finish (Tf ) temperatures of the ? ? ? phase change are found to be (1072±10)K and (1156±10)K, respectively. In the actual ? ? ? phase transformation region, the variation of the enthalpy with the progress of transformation is found to follow a sigmoidal shape which is in line with the diffusive nature of the phase transformation. An estimation of the total enthalpy change associated with the ? ? ? phase transformation ( ??Htr) has been made by assuming a simple diffusion limited kinetic model for the phase change. The net enthalpy change for the ? ? ? transformation is found to be 76 J · g?1. The measured temperature variation of the enthalpy increment in both ?- and ?-phase regimes are fitted to simple analytical functional forms to obtain temperature-dependent estimates of the specific heat, Cp. The total specific heat change associated with the ? ? ? phase transformation ??Cp(? ??) is estimated to be 904 J · kg?1 · K?1.
Madhusmita Behera, S. Raju, B. Jeyaganesh,,R. Mythili, S. Saroja, Int J Thermophys (2010) 31:2246–2263

B2700 – Thermodynamics of Ca-Ga Alloys

The enthalpies of formation of the intermetallic compounds CaGa4, Ca3Ga8, and CaGa2, at 298.15 K, were determined by high-temperature liquid gallium solution calorimetric measurements to be -24.9 ± 4.9 kJ.g at.-1, -25.4 ± 2.4 kJ.g at.-1, and -38.8 ± 4.8 kJ.g at.-1, respectively. The enthalpies of formation of CaGa4 at 988 K and that of Ca3Ga8 at 1070 K were determined, using precipitation calorimetry, to be -28.2 ± 1.7 kJ.g at.-1 and 22..5 ± 1.4 kJ.g at.-1, respectively. The integral enthalpy of mixing of the (Ca-Ga) liquid alloys (DH0) measured at 1309 K are described by the following Redlich–Kister equation. The partial enthalpy of calcium in gallium at infinite dilution (?H0 Ca), deduced from the measured integral enthalpies of mixing at 1309 K, is -104.8 ± 1.7 kJ.g at.-1, which is in very good agreement with that derived from the gallium solution calorimetric measurements at 1074 K (-108.2 ± 6.9 kJ.g at.-1).
B. Prabhakara Reddy, R. Babu, K. Nagarajan, P.R. Vasudeva Rao, Metallurgical and Materials Transactions B, Volume 30B, June 1999—459

B2687 – DSC study of the kinetic parameters of the metastable phases formation during non-isothermal annealing of an Al–Si–Mg alloy

Kinetics of ?'' and ?' precipitations in an AlSiMg have been studied under non-isothermal conditions using differential scanning calorimetry (DSC) technique. The variation of the activation energy as a function of transformed fraction is determined using two isoconversional methods of Kissinger–Akahira–Sunose (KAS) and Friedman. The results obtained using the two methods show a change in the activation energy for both metastable phases precipitations as a function of transformed fraction. The results obtained from KAS method as compared with those obtained from Friedman method, show some major disagreements between the two methods. The growth exponent, determined by Ozawa method, decreases as a function of temperature for both phases.
Mourad Ibrahim Daoudi, Abdelhafid Triki, Abdelkrim Redjaimia, J Therm Anal Calorim (2011) 104, 627–633

B2684 – Continuous cooling precipitation diagrams of Al–Mg–Si alloys

The temperature and time dependent precipitation behaviour of Albased 6060, 6063, 6005A and 6082 alloys at different cooling rates after solution annealing has been investigated. The continuous cooling precipitation diagrams of these alloys were recorded by differential scanning calorimetry. The cooling rate was varied over five orders of magnitude (0.05–20,000 K/min). Cooling rate dependent precipitate formation was analysed by light microscopy, scanning and transmission electron microscopy. Cooling rate dependent hardness was tested after artificial ageing. Over an appropriate range of cooling rates all alloys show similar precipitation behaviour. At least two precipitation reactions were observed in different temperature ranges. The high temperature reactions correspond to the precipitation of the equilibrium phase Mg2Si, and the low temperature reactions correspond to the precipitation of precursor phases such as b? and B? . The precipitation kinetics depends on the alloy composition. Maximum hardness values are to find as long as the materials were cooled faster than alloy specific critical cooling rate, which increases with increasing alloy content.
Benjamin Milkereit, Nelia Wanderka, Christoph Schick, Olaf Kessler, Materials Science and Engineering A 550 (2012) 87– 96

B2677 – A thermodynamic description of the Al-Fe-Si system over the whole composition and temperature ranges via a hybrid approach of CALPHAD and key experiments

A consistent thermodynamic data set for the Al-Fe-Si system over the entire composition and temperature ranges is obtained by using CALPHAD approach applied to predominant literature data, supplemented with the present experimental data resulting from Xray diffraction, differential thermal analysis, electron probe microanalysis, and enthalpy measurements of decisive alloys. Numerous comparisons between the calculated and measured phase diagrams as well as thermodynamic quantities indicate that almost all of the reliable experimental information is satisfactorily accounted for by the present thermodynamic modeling. The inconsistency between the measured and computed enthalpies of formation via CALPHAD method for the ternary compounds is traced to the FeeSi system in which there is a disagreement between the experimental enthalpy of formation and CALPHAD type one. The reliability of calculated thermodynamic properties for ternary phases is verified through enthalpy measurement employing drop calorimetry. A hybrid approach of CALPHAD method and key experiment to acquire a thermodynamic description of a complex ternary system is recommended.
Yong Du, Julius Clemens Schuster, Zi-Kui Liu, Rongxiang Hu, Philip Nash, Weihua Sun, Weiwei Zhang, Jiong Wang, Lijun Zhang, Chengying Tang, Zhijun Zhu, Shuhong Liu, Yifang Ouyang, Wenqing Zhang, Nataliya Krendelsberger, Intermetallics 16 (2008) 554-570

B2675 – Enthalpy of mixing of liquid systems for lead free soldering: Ni–Sb–Sn system

The partial and integral enthalpies of mixing of liquid ternary Ni–Sb–Sn alloys were determined along five sections xSb/xSn = 3:1, xSb/xSn = 1:1, xSb/xSn = 1:3, xNi/xSn = 1:4, and xNi/xSb = 1:4 at 1000 ?C in a large compositional range using drop calorimetry techniques. The mixing enthalpy of Ni–Sb alloys was determined at the same temperature and described by a Redlich–Kister polynomial. The other binary data were carefully evaluated from literature values. Our measured ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Toop is given. The entire ternary system shows exothermic values of 1mixH ranging from approx. ?1300 J/mol, the minimum in the Sb–Sn binary system down to approx. ?24,500 J/mol towards Ni–Sb. No significant ternary interaction could be deduced from our data.
A. Elmahfoudi, S. Fürtauer, A. Sabbar, H. Flandorfer, Thermochimica Acta 534 (2012) 33– 40

B2653 – Separation of overlapping retained austenite decomposition and cementite precipitation reactions during tempering of martensitic steel by means of thermal analysis

During isochronal tempering of martensitic steels, several decomposition reactions take place within to some extent overlapping temperature regions. For the kinetic study of these reactions, differential scanning calorimetry and dilatometry are well established complementary experimental techniques. During tempering stages II and III of martensitic steels with increased carbon contents, the simultaneous transformation of retained austenite and the precipitation of cementite produce strong signals as well in the differential scanning calorimeter as in the dilatometer. For the determination of the individual kinetic parameters and reaction enthalpies, these reactions have to be separated, which is attempted in the present study. This is accomplished by tempering room temperature quenched as well as liquid nitrogen quenched specimens in a differential scanning calorimeter. The investigated material is the SAE 1070, a spring-steel with 10 vol% retained austenite after quenching to room temperature. The data evaluation procedure is explained in detail and the results are compared with literature data.
S. Primig, H. Leitner, Thermochimica Acta 526 (2011) 111–117

B2650 – Nucleation Barriers for the Liquid-To-Crystal Transition in Ni: Experiment and Simulation

Nucleation in undercooled Ni is investigated by a combination of differential scanning calorimetry (DSC) experiments and Monte Carlo (MC) simulation. By systematically varying the sample size in the DSC experiments, nucleation rates J over a range of 8 orders of magnitude are obtained. Evidence is given that these rates correspond to homogeneous nucleation. Free energy barriers G , as extracted from the measured J, are in very good agreement with those from the MC simulation. The MC simulation indicates a nonspherical geometry of crystalline clusters, fluctuating between prolate and oblate shape at a given size. Nevertheless, the temperature dependence of G is well described by classical nucleation theory.
J. Bokeloh, R. E. Rozas, J. Horbach, G. Wilde, Physical Review Letter 107, 145701 (2011)

B2644 – Enthalpies of formation of Nb–Ru and Nb–Ru–Al alloys

The enthalpies of formation of Nb–Ru alloys in the whole range of composition and of two compositions in the Nb–Ru–Al ternary system corresponding to Nb(Ru,Al)2 and NbRu2Al identified by Cerba et al. [P. Cerba, M. Vilasi, B. Malaman, J. Steinmetz, J. Alloys Compd. 201 (1993), 57–60], have been measured by high-temperature direct reaction synthesis calorimetry at 1775 K. For some binary alloys the experiment cannot provide results because the direct reaction synthesis is not completed contrarily to ternary alloys experiments. The results are compared with predicted ab initio data.
My.Y. Benarchid, N. David, J.-M. Fiorani, M. Vilasi, T. Benlaharche, Thermochimica Acta, 482 (2009) 39–41

B2643 – Enthalpies of formation of Mo–Ru and Mo–Ru–Si compounds determined by high-temperature direct reaction synthesis calorimetry

The enthalpies of formation of (Ru) hcp solid solution and Mo5Ru3 (? phase) in the Mo–Ru system and ternary extension in the Mo–Ru–Si system at Mo56Ru37Si7 composition, have been determined by high-temperature direct reaction synthesis calorimetry at 1760 K. The following values are reported: ?fH1760 K(Ru) = ?10.6 ± 0.5 kJ/mol at.%; ?fH1760 K(Mo5Ru3) = ?7.4 ± 0.4 kJ/mol at.%; ?fH1760 K(Mo56Ru37Si7) = ?13.1 ± 3.3 kJ/mol at.%. The results are compared with the previous values derived from e.m.f. measurements. They are also compared with the predicted values obtained by Calphad, by ab initio method combined to Calphad modelling, and derived from a thermodynamic database named “TM16.TDB”.
My. Y. Benarchid, N. David, J.-M. Fiorani, M. Vilasi, Thermochimica Acta, 494 (2009) 26–29

B2635 – Recording of continuous cooling precipitation diagrams of aluminium alloys

The purpose of this report is to present a methodology to record continuous cooling precipitation (CCP) diagrams over the complete range of technical interesting cooling rates for some aluminium wrought alloys. With the information out of CCP-diagrams, the quenching step of the heat-treatment process “Age Hardening” can be optimized. The nanosized precipitations were detected via Differential Scanning Calorimetry (DSC) by identifying their exothermal heat. Aluminium wrought alloy EN AW-6005A was age hardened in three different DSCs whereby cooling rate range varies over 3 orders of magnitude. With increasing cooling rate, the precipitation heat is decreasing. The CCP-diagram covers cooling rates form close to equilibrium conditions at 0.1 K/min up to the critical cooling rate at 375 K/min where the precipitation reaction is suppressed completely. The DSC delivers a very useful method to record full range CCP-diagrams of aluminium alloys. Opposite to other possible methods, it also delivers a measure for the amount of the nanosized precipitates by the amount of released heat. A strategy is presented for the deconvolution of overlapping DSC-peaks.
Benjamin Milkereit, Olaf Kessler, Christoph Schick, Thermochimica Acta, 492 (2009) 73–78

B2634 – Precipitation kinetics of an aluminium alloy during Newtonian cooling simulated in a differential scanning calorimeter

The purpose of this report is to compare linear and non-linear cooling with respect to the precipitation behaviour of aluminium alloy EN AW-6082. Therefore an approximation of gas cooling by Newtonian law was performed. However, DSCs are typically designed for linear scanning. Hence a completely new method has been developed, to perform DSC-experiments during non-linear cooling. The temperature/time profile for two different types of DSCs was optimized avoiding overshoots at each change of cooling rate. Smooth curves were obtained by normalizing the measured heat flow rate by the actual heating rate yielding excess heat capacity as function of temperature. For the investigated aluminium alloy EN AW-6082 both kinds of cooling, linear and Newtonian, delivered comparable information about the characteristic precipitation reactions. Essential parts of the continuous cooling precipitation diagram could be recorded for both types of cooling. The intensities of the reactions, measured by the specific precipitation heat, were similar.
Benjamin Milkereit, Martin Beck, Michael Reich, Olaf Kessler, Christoph Schick, Thermochimica Acta, 522 (2011) 86–95

B2630 – Heat capacities of several Al–Ni–Ti compounds

The heat capacities of several Al–Ni–Ti compounds were determined by drop calorimetry over the temperature range of 500–1500 K. A modified Einstein model and a two-parameter polynomial model provide reasonable representations of the experimental heat capacity data. The heat capacities, Cp, using a two-parameter polynomial representation are as follows: Ni0.5Ti0.5, Cp = 22.39 + 8.24 × 10?3 T (J/(mol K)); Al0.45Ni0.5Ti0.05, Cp = 23.01 + 5.12 × 10?3 T (J/(mol K)); Al0.16Ni0.74Ti0.10, Cp = 18.36 + 10.76 × 10?3 T (J/(mol K)); and Al0.25Ni0.5Ti0.25, Cp = 25.38 + 1.088 × 10?3 T (J/(mol K)). The experimental data are compared with the values derived from a thermodynamic database of Gibbs energy functions. The analysis shows that (1) either model is a good representation of the data; (2) it is not adequate to assume the Neumann-Kopp rule for the description of the heat capacities of Al0.45Ni0.5Ti0.05, Al0.16Ni0.74Ti0.10 and Al0.25Ni0.5Ti0.25; (3) it is not appropriate to determine a compound Cp from a thermodynamic database of Gibbs energy functions if the compound is modeled by using the Neumann-Kopp rule and any of its components undergoes melting in the temperature range of interest.
Rongxiang Hu, Philip Nash, Qing Chen, Lijun Zhang, Yong Du, Thermochimica Acta, 486 (2009) 57–65

B2627 – Thermochemistry of Pd–In, Pd–Sn and Pd–Zn alloy systems

The standard enthalpy of formation of several Pd–M alloys (M = In, Sn and Zn) has been measured using a high temperature direct drop calorimeter. The reliability of the calorimetric results has been determined and supported by using different analytical techniques: light optical microscopy, scanning electron microscopy equipped with electron probe microanalysis (EPMA with EDS detector) and X-ray powder diffraction analysis. The values of ?fH (kJ/mol atoms) for the following phases were obtained for the formation in the solid state at 300 K: PdIn (49 at.%In): ?69.0 ± 1.0; Pd2In3 ?57.0 ± 1.0; Pd3In7: ?43.0 ± 1.0; PdSn2: ?50.0 ± 1.0; Pd2Zn9 (77 at.%Zn): ?33.7 ± 1.0; Pd2Zn9 (78 at.%Zn): ?34.0 ± 1.0; Pd2Zn9 (80 at.%Zn): ?35.0 ± 1.0. The results show exothermic values which increase from the Pd–Zn to the Pd–Sn and Pd–In systems; the data obtained have been discussed in comparison with those available in literature
S. Amore, S. Delsante, N. Parodi, G. Borzone, Thermochimica Acta, 481 (2009) 1-6

B2626 – Partial and integral enthalpies of mixing of Ag–Ga–Sn liquid alloys

A Calvet type calorimeter was used for measurement of partial and integral enthalpies of mixing of Ag–Ga–Sn alloys. The Ag–Ga binary alloys have been studied with 0 < xAg < 0.79 composition and in the 803–1073 K temperature range. The mixing enthalpies at 803 K of Ga–Sn binary alloys have been determined for xSn < 0.35. The Ag–Ga–Sn ternary liquid alloys have been investigated at 803 K along the following sections: xAg/xGa = 1/3, xAg/xGa = 0.36/0.64, xAg/xGa = 1/1, xGa/xSn = 1/3, xGa/xSn = 1/1, xGa/xSn = 0.65/0.35 and xGa/xSn = 3/1. Experimental data were used to obtain the binary interaction parameters by using the Redlich–Kister polynomial for the Ag–Ga binary system, while the Redlich–Kister–Muggianu method was used to determine the ternary interaction parameters for the Ag–Ga–Sn system. The experimental values and the fitted curves were compared with those predicted from the Muggianu and Toop methods.
D. Li, S. Delsante, W.Gong, G. Borzone, Thermochimica Acta, 523 (2011) 51-62

B2625 – Heat contents of the intermetallics V3Ge and V5Ge3 and thermodynamic modeling of the Ge–V system

Fourteen alloys were prepared by arc-melting the pure elements and annealing the alloys at 850 °C for 30 days. The annealed alloys were examined by X–ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray analysis (SEM/EDX), differential scanning calorimetry (DSC) and drop calorimeter. The major experimental results are as follows. (I) The heat contents of V3Ge and V5Ge3 were measured by drop calorimeter from 400 to 900 °C. (II) The microstructure analysis of as-cast alloy V87.1Ge12.9 indicates that the eutectic composition of liquid ? (V) + V3Ge is above 12.9 at.% Ge, and that of V2.9Ge97.1 shows that the eutectic composition of liquid ? V17Ge31 + Ge is close to 97.1 at.% Ge. (III) The invariant reaction temperatures of liquid + V11Ge8 ? V17Ge31 and liquid ? V17Ge31 + Ge are at 960.0 ± 2 °C and 930.7 ± 2 °C, respectively. Based on the experimental results in this study and in the literature, the Ge–V system was modeled by CALPHAD approach.
Xiaoming Yuan, Weihua Sun, Yoonsung Chung, Honghui Xu, Shuhong Liu, Yong Du, Philip Nash, Dewen Zeng, Thermochimica Acta, 513 (2011) 100–105

B2624 – Enthalpies of mixing of liquid systems for lead free soldering: Al–Cu–Sn system

The present work refers to high-temperature drop calorimetric measurements on liquid Al–Cu, Al–Sn, and Al–Cu–Sn alloys. The binary systems have been investigated at 973 K, up to 40 at.% Cu in case of Al–Cu, and over the entire concentrational range in case of Al–Sn. Measurements in the ternary Al–Cu–Sn system were performed along the following cross-sections: xAl/xCu = 1:1, xAl/xSn = 1:1, xCu/xSn = 7:3, xCu/xSn = 1:1, and xCu/xSn = 3:7 at 1273 K. Experimental data were used to find ternary interaction parameters by applying the Redlich–Kister–Muggianu model for substitutional solutions, and a full set of parameters describing the concentration dependence of the enthalpy of mixing was derived. From these, the isoenthalpy curves were constructed for 1273 K. The ternary system shows an exothermic enthalpy minimum of approx. ÿ18,000 J/mol in the Al–Cu binary and a maximum of approx. 4000 J/mol in the Al–Sn binary system. The Al–Cu–Sn system is characterized by considerable repulsive ternary interactions as shown by the positive ternary interaction parameters.
Hans Flandorfer, Meryem Rechchach, A. Elmahfoudi, László Bencze, Arkadij Popovic, Herbert Ipser, J. Chem. Thermodynamics 43 (2011) 1612–1622

B2619 – Enthalpy of formation of the La–Mg intermediate phases

The aim of this work is to complete the available set of thermodynamic data on the La–Mg system in order to get reliable optimisation of this system by the CALPHAD method. Indeed the CALPHAD method requires a large set of consistent input data including both phase diagram and thermodynamic data. The enthalpies of formation of the La–Mg intermediate compounds were determined at 298 K by means of solution calorimetry in liquid Sn in a Tian–Calvet calorimeter. In these experiments, the partial enthalpies of solution of the compounds at infinite dilution in liquid tin were measured at 665 K. The enthalpies of formation of LaMg, LaMg2 and La2Mg17 compounds were also calculated at 0 K by density functional theory to compare experimental and calculated values.
A. Berche, F. Marinelli, J. Rogez, M.-C. Record, Thermochimica Acta, 499 (2010) 65–70

B2618 – Calorimetric investigations of Au–In, In–Sb and Au–In–Sb systems at 973 K

The molar enthalpies of mixing of the Au–In, In–Sb and Au–In–Sb alloys have been determined at 973 K using a Calvet hightemperature microcalorimeter by the drop method. Measurements in the ternary system Au–In–Sb were performed along four sections, xAu/xIn = 1/3–1/1 and xIn/xSb = 1/1–3/1. The experimental calorimetric data and estimated values with a Redlich–Kister–Muggianu formulation are compared.
S. Hassam, D. Boa, J. Rogez, Journal of Alloys and Compounds 520 (2012) 65– 71

B2566 – Critical assessment and optimization of the Ag–Au–Pb system

By means of an optimization procedure, the ternary Ag–Au–Pb system has been assessed. All available experimental data of the ternary system and the results derived from thermodynamic descriptions for the three limiting binary systems are used. For the Ag–Au and Au–Pb systems, optimized Gibbs energy expressions were taken from the literature. A new assessment of the binary Ag–Pb system based on our calorimetric investigations is presented in this paper.Calculated phase diagrams and some calculated thermochemical functions for the binary Ag–Pb and the ternary Ag–Au–Pb systems are compared with experimental data.
S. Hassam, D. Boa, P. Benigni, J. Rogez, Thermochimica Acta, 510 (2010) 37–45

B2563 – Enthalpies of mixing of liquid systems for lead-free soldering: Cu–Sb–Sn system

Using two different types of high temperature drop calorimeters, partial and integral enthalpies of mixing of liquid alloys were determined in the ternary Cu–Sb–Sn system. The system was investigated along four sections at 1100 K. Experimental data were used to find ternary interaction parameters by applying the Redlich–Kister–Muggianu model for substitutional solutions, and a full set of parameters describing the concentration dependence of the enthalpy of mixing was derived. From these, the isoenthalpy curves were constructed for 1100 K. The entire system shows exothermic enthalpy of mixing at the given temperature.
Dominika Jendrzejczyk-Handzlik, Meryem Rechchach, Wojciech Gierlotka, Herbert Ipser, Hans Flandorfer, Thermochimica Acta, 512 (2011) 217-224

B2561 – The determination of the integral enthalpies of mixing of liquid Au–In–Sn alloys and the enthalpy of formation of the Au4In3Sn3 compound

With a view to modelling the Au–In–Sn alloy system, the enthalpies of mixing of liquid Au–In–Sn alloys have been measured as a function of Au content by drop calorimetry at 609 °C for constant In:Sn ratios of 1:1, 1:3 and 3:1. For each of the three sections studied, the enthalpies of mixing were exothermic. In addition, the enthalpy of formation of the ternary Au4In3Sn3 at 298 K was measured both by direct-reaction calorimetry and by tin-solution calorimetry
A. Watson, G. Borzone, N.Parodi, G. Cacciamani, Thermochimica Acta, 510 (2010) 24–31

B2560 – Thermodynamics of the Al3Ni phase and revision of the Al–Ni system

The heat capacity of the Al3Ni phase had been measured for the first time, by means of relaxation method over the low temperature range 2–323 K and by measuring heat content increments using drop calorimetry over the higher temperature range of 583–1073 K. The Debye function was employed to fit the low-temperature heat capacities, and from the function, the absolute entropy was evaluated, . A three-term polynomial representation, a + b·T + c·T?2, was used for describing heat capacity above 298.15 K. The Gibbs energy function of the Al3Ni phase was derived with a fixed reference state by incorporating the polynomial expression of the heat capacity, the recently reported enthalpy of formation and the related phase equilibria in the Al–Ni system. A revised thermodynamic description of the entire Al–Ni system together with the calculated phase diagram is also presented.
H.-L. Chen, E. Doernberg, P. Svoboda, R. Schmid-Fetzer, Thermochimica Acta, 512 (2011) 189–195

B2559 – Thermodynamic properties of liquid silver–gallium alloys determined from e.m.f. and calorimetric measurements

The thermodynamic properties of the liquid Ag–Ga alloys were determined using e.m.f. and calorimetric methods. In the e.m.f. method, solid oxide galvanic cells were used with zirconia electrolyte. At first, the Gibbs free energy of formation of pure solid gallium oxide, Ga2O3, from pure elements was derived. Using values of the measured e.m.f. for the cell with xGa = 1.0, the following temperature dependence was obtained. Next, the activity of the gallium was derived as a function of the alloy composition from the values of the measured e.m.f. Activities of silver were calculated using the Gibbs–Duhem equation. The drop calorimetric measurements were carried out at two temperatures, viz. 923 K and 1123 K, using a Setaram MHTC calorimeter. Integral enthalpies of mixing of liquid binary alloys were determined at those temperatures. Finally, thermodynamic properties of the liquid alloys were described with the Redlich–Kister equation using ThermoCalc software.
Dominika Jendrzejczyk-Handzlika, Krzysztof Fitzner, The Journal of Chemical Thermodynamics, 43, 3 (2011) 392–398

B2558 – Physicochemical investigation of platinum dichloride polymorphism

The physicochemical characteristics of phase transitions of PtCl2 were investigated for the first time. The irreversible character of the transition from ?-modification to ?-form of PtCl2 and the temperature range of process were established (570–870 K). ?-PtCl2 has one reversible transition at a temperature of 660 ± 5 K; the thermal effect of this process is +167 ± 17 J/mol.
Tamara P. Chusova, Zinaida I. Semenova, Thermochimica Acta, 469 (2008) 77-85

B2557 – Kinetics of intermetallic phase formation in the Ti/Al multilayers

The kinetics of the synthesis of elemental nanoscaled multilayers of Ti and Al in the regime of continuous heating from 300 K up to 973 K was investigated. A series of sputter deposited Ti/Al multilayer thin films with individual layer thickness (d) from 4 nm up to 1000 nm have been used. Differential scanning calorimetry, Friedman–Gupta, Kissinger and Suriñach methods of complex kinetic analysis, classical and time resolved X-ray diffraction and scanning electron microscopy have been applied. In the Ti/Al multilayers the sequence of reactions leading to the final product TiAl (and Ti3Al) is determined. The final products as well as the kinetics of their formation depend on the individual layer thickness. Three different kinetic regimes depending on the layer thicknesses have been found.
Emília Illeková, Jean-Claude Gachon, Alex Rogachev, Hamazasp Grigoryan, Julius Clemens Schuster, Anton Nosyrev, Petr Tsygankov, Thermochimica Acta, 469 (2008) 77-85

B2548 – Phase transformation and phase diagram at equilibrium in the Cu–Ni–Sn system

The Cu–Ni–Sn ternary phase diagram in the Cu rich side has not been experimentally determined or calculated at low temperatures. Two Cu9NixSn alloys with x=2 and 6 mass% Sn were studied. The precipitation sequence during the ageing and phases responsible for the strengthening were determined.
F. Sadi, C. Servant, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 2, 319–323

B2547 – Study on the effect of mechanical alloying on properties of Zn–Sb alloy

The effect of mechanical alloying on Zn–Sb alloy system is investigated with X-ray diffraction (XRD), laser grain size analysis and differential scanning calorimetry (DSC) respectively. The results of laser particle size analysis shows that the particle size decreases with increasing of the grinding time between 0 and 24 h. XRD and DSC results indicate that longer the grinding time of Zn–Sb is, the more content of Zn4Sb3 become in the product in this process.
Z. L. Xiao, D. Liu, C. F. Wang, Z. Cao, X. F. Zhan, Z. L. Yin, Q. Y. Chen, H. L. Liu, F. Xu, L. X. Sun, Journal of Thermal Analysis and Calorimetry, Vol. 95 (2009) 2, 513–515

B2462 – Recrystallization of pure copper investigated by calorimetry and microhardness

The recrystallization of cold rolled copper has been investigated using both differential scanning calorimetry (DSC) and Vickers microhardness techniques. The activation energy of the recrystallization process has been determined by microhardness and by DSC under isochronal conditions. The DSC results have been analyzed using models developed by Kissinger, Ozawa and Boswell. In addition, the recrystallized fraction, as a function of temperature, has been determined from the DSC analysis and compared to that obtained by microhardness measurements.
G. Benchabane, Z. Boumerzoug, I. Thibon, T. Gloriant, Materials Characterization 59 (2008) 1425-1428

B2450 – Mechanism and kinetics of the formation of zinc pack coatings

A zinc deposition method that could be used instead hot-dip galvanizing is pack cementation, where the substrate is heated immersed in a powder mixture containing Zn and a halide activator (NH4Cl). In the present work the mechanism of this process is examined, along with the effect of temperature and heating time on the coating thickness and structure. For this purpose the coating was deposited and characterized with SEM, while the deposition mechanism was investigated with DSC. From the above examination it was deduced that the deposition of Zn takes place with a multiple-step mechanism, which involves several reactions in the gaseous phase including the formation of volatile zinc halides and finally the diffusion of zinc in the crystal lattice of the ferrous substrate. This procedure is accomplished at about 300°C and leads to the growth of a coating composed by two layers referring to and phase of the Fe–Zn system. The coating deposition rate seems to be controlled by the zinc diffusion as its determination at 300 and 350°C showed, where it was deduced that the coating thickness is a linear function of the square root of heating time. However the coating structure is not affected by the heating time and temperature
G. Vourlias, N. Pistofidis, K. Chrissafis, E. Pavlidou, G. Stergioudis, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 497–501

B2433 – Enthalpy increment and heat capacity of Pb3Bi

Enthalpy increments of Pb0.71Bi0.29 compound and enthalpy change associated with peritectic decomposition reaction of the compound were determined using high temperature Calvet calorimeter. The heat capacity of the compound was determined in the temperature range 230–440K using heat flow DSC. The enthalpy increment data was fitted into the following polynomial equations. ?T 298.15K (J/mol) = ?6492.2 + 21.2775T + 0.00919T2 ? 199, 341/T (298.15–457 K) The enthalpy of decomposition reaction of the compound at the peritectic temperature, 457 K, was found to be 984 J/mol. The heat capacity of the compound determined using DSC was fitted into the following polynomial equation. Cp (J/mol K) = 23.486 ? 0.01482T + 97, 338.4/T2 (228–457 K) The heat capacity values obtained from DSC were in reasonably good agreement with the values calculated from enthalpy increment equation and both were slightly higher than the heat capacity values calculated using Neumann–Kopp’s rule.
Renu Agarwal, Pradeep Samui, Journal of Alloys and Compounds 508 (2010) 333–337

B2419 – Thermodynamic properties of liquid silver–gallium alloys determined from e.m.f. and calorimetric measurements

The thermodynamic properties of the liquid Ag–Ga alloys were determined using e.m.f. and calorimetric methods. In the e.m.f. method, solid oxide galvanic cells were used with zirconia electrolyte. The cells of the type W, AgxGa(1-x), Ga2O3 // ZrO2 + (Y2O3)//FeO, Fe, W were used in the temperature range from 1098 K to 1273 K, and in the range of mole fraction from xGa = 0.1 to xGa = 1.0. At first, the Gibbs free energy of formation of pure solid gallium oxide, Ga2O3, from pure elements was derived. Using values of the measured e.m.f. for the cell with xGa = 1.0, the following temperature dependence was obtained: ?fGm(Ga2O3) (± 4 kJ.mol 1) = -1061.7235 + 0:2899T/K: Next, the activity of the gallium was derived as a function of the alloy composition from the values of the measured e.m.f. Activities of silver were calculated using the Gibbs–Duhem equation. The drop calorimetric measurements were carried out at two temperatures, viz. 923 K and 1123 K, using a Setaram MHTC calorimeter. Integral enthalpies of mixing of liquid binary alloys were determined at those temperatures. Finally, thermodynamic properties of the liquid alloys were described with the Redlich–Kister equation using ThermoCalc software
Dominika Jendrzejczyk-Handzlik, Krzysztof Fitzner, J. Chem. Thermodynamics 43 (2011) 392–398

B2418 – Enthalpy of formation of selected mixed oxides in a CaO–SrO–Bi2O3–Nb2O5 system

The heats of drop-solution in 3Na2O+4MoO3 melt at 973K and 1073K for calcium and strontium carbonates, Bi2O3, Nb2O5 and several stoichiometric mixed oxides in CaO–Nb2O5, SrO–Nb2O5 and Bi2O3–Nb2O5 systems were measured using a Setaram Multi HTC-96 calorimeter. The values of enthalpy of formation from constituent binary oxides at 298 K, ?oxH, were derived for the mixed oxides under investigation: ?oxH(CaNb2O6) =?132.0±23.8 kJ mol?1, ?oxH(Ca2Nb2O7) =?208.0±31.9 kJ mol?1, ?oxH(SrNb2O6) =?167.9±19.1 kJ mol?1, ?oxH(Sr2Nb2O7) =?289.2±37.5 kJ mol?1 and ?oxH(BiNbO4) =?41.9±11.1 kJ mol?1. Additionally, the values ?oxH for other mixed oxides with different stoichiometries were estimated on the basis of these experimental results.
J. Leitner, M. Nevriva, D. Sedmidubsky, P. Vonka, Journal of Alloys and Compounds 509 (2011) 4940–4943

B2399 – Enthalpies of formation of Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 intermetallic compounds

Cadmium is expected to be the solvent for pyrochemical processing of the metallic nuclear fuel. Therefore, thermodynamic properties of cadmium with various fuel and clad elements are of interest. Enthalpies of formation of the intermetallic compounds of Cd–Sr system, Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 were determined by precipitation using Calvet calorimeter. Enthalpies of formation of the compounds were found to be ?3.05±0.5 kJ mol?1 at 723 K, ?14.2±0.7 kJ mol?1 at 843K and ?28.4±0.8 kJ mol?1 at 863 K, respectively. Enthalpies of formation of Cd0.917Sr0.083 and Cd0.857Sr0.143 were also determined by partial enthalpy of formation measurements and the values were found to be ?3.9±1.1 kJ mol?1 at 723K and ?13.42±1.2 kJ mol?1 at 843 K, respectively. Miedema model was used to estimate the enthalpies of formation of these compounds and the estimated values were compared with the experimentally determined values.
Renu Agarwal, Ziley Singh, Journal of Alloys and Compounds 448 (2008) 166–170

B2372 – Calorimetric investigation of the Cu–Sn–Bi lead-free solder system

The thermodynamic properties play a crucial role in the development of new solder materials. In this work a calorimetric investigation of the ternary Cu–Sn–Bi system was carried out by using a Calvet-type calorimeter in order to obtain the molar limiting partial enthalpy of Cu in liquid Sn–Bi alloys with different compositions. The molar limiting partial enthalpy of Cu at 820 K was determined in the Sn–75 at% Bi, Sn–43 at% Bi and Sn–26 at% Bi liquid bath showing an endothermic behaviour. The results are compared with the literature data available for Cu in the pure liquid Bi and Sn and then discussed
S. Amore, S. Delsante, N. Parodi, G. Borzone, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 227–232

B2324 – Standard enthalpy of formation of compounds of the Cd–Zr system

Thermodynamic properties of two intermetallic phases CdZr2(s) and Cd3Zr(s) in the binary Cd–Zr system have been investigated. The standard molar enthalpy of formation ?fH°298 of CdZr2(s) and Cd3Zr(s) was obtained by measuring the reaction enthalpy of CdZr2(s), Cd3Zr(s) and Zr(s), respectively, using Cd(l) in a Calvet calorimeter. The values of ?fH°298 of CdZr2(s) and Cd3Zr(s) at 298 K were found to be -(61.7 ± 1.2) kJ mol-1 and -(72.3 ± 0.9) kJ mol-1, respectively.
S. Phapale, R. Mishra, D. Das, Journal of Nuclear Materials 375 (2008) 259–262

B2322 – Review: Experimental enthalpies of formation of compounds in Al-Ni-X systems

The published experimental enthalpies of formation for compounds in the Al-Ni-X ternary system are reviewed. Most of these experimental data were obtained by either solution calorimetry or high temperature direct synthesis calorimetry. Data for the Al-Ni-Cu compounds determined by the current authors using direct synthesis calorimeter are presented for the first time
Rongxiang Hu, Philip Nash, J. Mater. Sci. 4 1 (2 0 0 6 ) 6 3 1 –6 4 1

B2321 – Study of secondary intermetallic phase precipitation/dissolution in Zr alloys by high temperature–high sensitivity calorimetry

It is well established that in Zr alloys, secondary precipitate phases (SPP) have a major influence on the materials properties (corrosion and mechanical behaviour). Thus, it is of great importance to know the SPP formation and dissolution temperatures and their possible metastability as a function of the alloy chemical composition, the thermal treatments and the SPP characteristics (crystallographic structure and chemical composition). The aim of the present paper is to give an overview of the studies performed recently on different alloy families, i.e., Zr–Fe–V, Zr–Fe–Mo, Zr–Nb–Fe and Zircaloy (Zr–Sn–Fe–Cr) types. High temperature–high sensitivity calorimetry (Setaram HF-DSC) has been extensively applied on these alloys. From the experimental thermograms, we have derived the SPP fraction evolution as a function of the temperature, and also the enthalpy associated with their dissolution upon heating and precipitation upon cooling. It has thus been possible to study the reversibility of the reactions involved. Depending upon the thermal diffusivities of the alloying elements, we have shown that the alloys studied can be classified into two sub-groups: (1) alloys with fast-diffusing elements, such as Cr, Fe, V, showing reversible phase transformations upon heating and cooling; (2) alloys with slow-diffusing elements, such as Nb or Mo, showing metastable phase transformations, that are characterised by a partial Zr-Beta decomposition and metastable SPP precipitation upon cooling. In addition, the sensitivity of calorimetric measurements to low fractions of SPP (less than 1%) is demonstrated
C. Toffolon-Masclet, T. Guilbert, J.C. Brachet, Journal of Nuclear Materials 372 (2008) 367–378

B2319 – Integral enthalpy of mixing of the liquid ternary Au–Cu–Sn system

The integral enthalpy of mixing of the ternary Au–Cu–Sn has been determined with a Calvet type calorimeter at 6 different cross sections at 1273 K. The substitutional solution model of Redlich–Kister–Muggianu was used for a least square fit of the experimental data in order to get an analytical expression for the integral enthalpy of mixing. The ternary extrapolation models of Kohler, Muggianu and Toop were used to calculate the integral enthalpy of mixing and to compare measured and extrapolated values. Additional calculations of the integral enthalpy of mixing using the Chou model have been performed. With the calculated data, the iso-enthalpy lines have been determined using the Redlich–Kister–Muggianu model. A comparison of the data has been made.
S. Knott, Z. Li, A. Mikula, Thermochimica Acta 470 (2008) 12–17

B2313 – Thermodynamic Assessment of the Ag–Au–Bi and Ag–Au–Sb systems

The aim of the action of COST 531 taking into account the eleven elements Ag,Au,Bi,Cu,In,Pb,Sb,Sn,Zr (solder), Ni and Pd (substrate) is the database assessment for candidates of lead free soldering process. We studied four of them forming the ternary systems Ag–Au–Bi and Ag–Au–Sb. First we determined experimentally their phase diagrams, then the integral enthalpy of mixing of the liquid phase along different sections at different temperatures by using a SETARAM device heat flow calorimeter of Tian-Calvet type. All these data were used to optimize the thermodynamic parameters of the different phases of both ternary systems.
E. Zoro, C. Servant and B. Legendre, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 2, 347–353

B2312 – Enthalpies of mixing of liquid In–Sn and In–Sn–Zn alloys

Partial and integral enthalpies of mixing of liquid ternary In–Sn–Zn alloys were determined at 500 ?C along seven sections over a large composition range. Additionally, binary alloys of the constituent system In–Sn were investigated at the same temperature. The measurements were carried out using a Calvettype microcalorimeter and a drop calorimetric technique. The binary data were evaluated by means of a standard Redlich–Kister polynomial fit whereas ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions.
M. Rechchach, A. Sabbar, H. Flandorfer, H. Ipser, Thermochimica Acta 502 (2010) 66–72

B2306 – Enthalpies of mixing of liquid Bi–Cu and Bi–Cu–Sn alloys relevant for leadfree soldering

Partial and integral enthalpies of mixing of liquid ternary Bi–Cu–Sn alloys at 800 ?C were determined along nine sections in a large composition range. Additionally, binary alloys of the constituent binary system Bi–Cu were investigated at 800 and 1000 ?C. Measurements were carried out using a Calvettype microcalorimeter and a drop calorimetric technique. The binary data were evaluated by means of a standard Redlich–Kister polynomial fit whereas ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions
Hans Flandorfera, Abdelaziz Sabbar, Christoph Luef, Meryem Rechchach, Herbert Ipser, Thermochimica Acta 472 (2008) 1–10

B2280 – Thermal stability and crystallization studies of amorphous TM-C films

During the last years, several binary transition metals (TM)-Carbon systems have been explored with the aim of, first obtaining amorphous alloys in a wide range of composition, especially towards the carbon-rich concentrations and second, studying the thermal stability and the crystallization of these new materials. Sputtering has been chosen as means of elaboration to obtain the films and electron probe microanalysis was used to determine the composition. The as-sputtered amorphous state was detected by electron diffraction and/or X-ray. For each amorphous film, the thermal stability was studied by differential scanning calorimetry and the crystallization was followed by hot-stage transmission electron microscopy. The products of crystallization were identified by electron diffraction. In this paper, we present a comparison of the main results we have got on amorphous and then crystallized films belonging to the well-known Fe-C, Mn-C and Cr-C systems. The thermal stability increases from Fe-C to Cr-C systems. Depending both on the carbon content and the nature of the transition metal, various unknown carbides form from the amorphous films. We find that they are often isomorphous with interstitial compounds already existing among borides, nitrides, carbonitrides and other carbides. The emphasis is put in their structural description. It is thus demonstrated that the new structures can offer either prismatic, octahedral or both sites to the C atoms. This suggests that more than one type of local orders may exist in the amorphous state for these TM-C systems.
E. Bauer-Grosse, Thin Solid Films 447-448 (2004) 311-315

B2269 – The effect of strain path and temperature on the microstructure developed in copper processed by ECAE

The microstructure of copper developed by equal channel angular extrusion (ECAE) to a strain ~8 was investigated using different strain path and temperature. Two different strain paths were obtained by rotating the billets through 90° (route BC) or 180° (route C) between each pass. In general, the microstructure should be characterized as a cold-worked structure with varied degree of recrystallization depending on the processing route and temperature. At room temperature, both routes produced similar microstructure except the formation of recrystallized grains by route BC. By the use of route BC, the volume fraction and size of recrystallized grains were found to increase with increasing deformation temperature, while the size of recrystallized grains showed considerable increase above 150°C. Comparing with aluminum deformed by ECAE at similar homologous temperature (~0.32Tm), the most distinct difference in the microstructure development is the presence of dynamic recrystallization in copper.
W.H. Huang, C.Y. Yu, P.W. Kao., C.P. Chang, Materials Science and Engineering A366 (2004) 221-228

B2268 – Combined study of crystallization of amorphous Fe(75-x)NixSi9B16 alloy

The crystallization of the amorphous Fe(75-x)NixSi9B16 alloy is studied by different methods. Particularly the influence of the substitution of Fe by Ni atoms on the crystallization properties of the material is investigated by transmission electron microscopy, linear heating differential scanning calorimetry, magnetization and electrical measurements. The crystallization process consists of three distinct steps. The crystallization starts with the formation of small Fe (Si, Ni) particles followed by the crystallization of the [Fe (Si, Ni)]3B phase together with the dendritic growth of Fe (Si, Ni). Finally the metastable [Fe (Si, Ni)]3B decomposes into Fe (Si, Ni) and Fe2B. In the 4 at.% Ni alloy the crystallization process changes completely and the crystallization is completed in two steps creating a nanostructured material.
K.G. Efthimiadis, K. Chrissafis, E.K. Polychroniadis, Materials Science and Engineering A366 (2004) 211-220

B2266 – Thermodynamic studies on Al-U-Zr alloy

The ternary alloys, Al0.9749U0.0216Zr0.0035, Al0.9607U0.0316Zr0.0077, Al0.940U0.0472Zr0.0088 and Al0.8933U0.0911Zr0.0156, were prepared by induction melting and casting. The enthalpy increment measurements were carried out using Calvet calorimetry. The enthalpy increment values as a function of temperature are least squares fitted to polynomial expressions using the constraint that H°(T)-H°(298.15 K)=0 at 298.15 K. The specific heat capacity expressions for these alloys have been derived and it is observed that Cp°(T) of U-Al-Zr alloy decreases with increasing U content.
S. Dash, Z. Singh, T.R.G. Kutty, S.C. Parida, V. Venugopal, Journal of Alloys and Compounds 365 (2004) 291-299

B2263 – Crystallization behaviour of Al87Ni7La6 and Al87Ni7Sm6

Devitrification in Al87Ni7La6 and Al87Ni7Sm6 alloys was investigated at the European Synchrotron Radiation Facility and by DSC, XRD and TEM. For Al87Ni7La6 the primary precipitating phase has a primitive cubic structure, while for Al87Ni7Sm6 alloy the primary phase is fcc-Al. Results are also presented for in situ melting of the alloys.
V. Ronto, L. Battezzati, A.R. Yavari, M. Tonegaru, N. Lupu, G. Heunen, Scripta Materialia 50 (2004) 839-843

B2261 – Kinetics and mechanism of formation and transformation of metastable beta’-phase in Al-Mg alloys

The analysis of dilatometric and calorimetric curves, completed by optical microscopy observations, permitted to follow the kinetics and the morphology changes of beta'-phase particles during ageing of Al-12 wt.%Mgalloy. It is nowwell established that beta'-phase particles, which are semi-coherent and metastable, appear initially in a globular shape, transform into thin needles, then into particles of the equilibrium beta-phase after a long ageing time, as predicted by the phase diagram. In addition, beta' and beta-phases are formed and dissolved successively and independently one of the other, during non-isothermal ageing.
D. Hamana, L. Baziz, M. Bouchear, Materials Chemistry and Physics 84 (2004) 112-119

B2260 – Vapour pressure and heat capacities of metal organic precursors, Y(thd)3 and Zr(thd)4

The vapour pressure of two metal organic precursors, Y(thd)3 [CAS RN: 15632-39-0] and Zr(thd)4 [CAS RN: 18865- 74-2] (thd=2,2,6,6-tetramethylheptane-3,5-dionate), used for metal organic chemical vapour deposition of hightemperature superconductor layers, was measured by a static method in the technologically important temperature range from 395 to 465 K. The experimental data were fitted by simple two-parameter equation and represent updated values of the present day high-purity materials providing comparison with the previously published data. Heat capacities in the temperature range from 308 to 565K are also reported.
M. Fulem, K. Ruzicka, V. Ruzicka, T. Simecek, E. Hulicius, J. Pangrac, Journal of Crystal Growth 264 (2004) 192-200

B2257 – On the synthesis of Zr-based bulk amorphous alloys from glass-forming compounds and elemental powders

The possibility of producing Zr-based bulk amorphous alloys (Zr65Cu17.5Ni10Al7.5 and Zr57Ti5Cu20Ni8Al10) by mechanical alloying (MA) from either a mixture of elemental powders (EP), or a mixture of glass-forming compounds (GFC), has been investigated. A preliminary study of the crystal structure stability of the GFC-ingredients during mechanical milling was performed. Amorphization was found to be significantly enhanced during MA by using a GFC mixture. A considerable difference in the phase transformations observed on heating the amorphous phase (AP) was noted for alloys obtained from GFC, as compared with those produced by melt quenching (MQ) or milling of a mixture of elemental powders. It is shown that the amorphous phase obtained by MA from GFC has a wider undercooled liquid region between the glass transition temperature Tg and the crystallization temperature Tx than the amorphous phase produced by the conventional MQ technique.
N.P. Djakonova, T.A. Sviridova, E.A. Zakharova, V.V. Molokanov, M.I. Petrzhik, Journal of Alloys and Compounds 367 (2004) 191-198

B2252 – Observation of changing of magnetic properties and microstructure of metallic glass Fe78Si9B13 with annealing

Magnetic measurements of metallic glass Fe78Si9B13 were taken using a DC inductive magnetometer. Samples were isothermally annealed in air at 773 K, and convenient annealing times were chosen for each step. For every annealing step, M-H plots were taken and coercivities obtained. Changes in coercivity were observed, and coercivity-annealing time graphs were plotted. The minimum coercivity was measured as 1.6 A/m at this fixed temperature. After each annealing step X-ray diffraction patterns and magnetic domain pictures were taken. Magnetic domain pictures were taken by the Bitter Technique. The observations are interpreted in terms of stress relief and sample crystallization. The appearance of zig-zag domain walls in the as-cast sample should be particularly noted. We show the development of regions of maze domains as surface crystallization onset occurs.
R. Sahingoz, M. Erol, M.R.J. Gibbs, Journal of Magnetism and Magnetic Materials 271 (2004) 74-78

B2239 – Influence of Gd addition on the magnetism and structure of Finemet-type nanocrystalline alloys

The effect of rare earth addition in the structure and magnetism of melt spun nanocrystalline Finemet-type alloys devitrified from amorphous precursor ribbons is discussed. Starting with the initial composition Fe73.5Cu1Nb3Si13.5B9 an amount of 5 at% Gd is introduced into the primary alloy. The purpose is to enable after appropriate recrystallization the occurrence of hard and soft magnetic, suitably dispersed, exchange-coupled nanograins and to determine the transformation sequences of the crystallization process and the obtained crystallization products.
O. Crisan, J.M. Le Breton, A.D. Crisan, F. Machizaud, Journal of Magnetism and Magnetic Materials 272-276 (2004) 1396-1397

B2218 – Thermodynamic properties of Sr2RuO4(s) and Sr3Ru2O7(s) by using solid-state electrochemical cells

The standard Gibbs free energies of formation of Sr2RuO4(s) and Sr3Ru2O7(s) have been determined using two types of solid-state electrochemical cells: one using CaF2(s) as the solid electrolyte, the fluoride cell and the other wherein calcia-stabilized zirconia (CSZ) has been used as the solid electrolyte, the oxide cell. The standard Gibbs free energies of formation of Sr2RuO4(s) and Sr3Ru2O7(s) from elements in their standard state, calculated by combining results obtained from fluoride and oxide cells, can be given respectively by: ?fG°[Sr2RuO4(s)](kJ mol-1)(±1) = -1595.8 + 0.3588(T(K)). ?fG°[Sr3Ru2O7(s)](kJ mol-1)(±1) = -2546.7 + 0.6010(T(K)). The enthalpy increments of Sr2RuO4(s) measured using a high-temperature Calvet micro-calorimeter can be represented by the polynomial expression: H°(T) - H°(298.15K)(J mol-1) = -69975.4 + 166.2(T/K) + 0.554 x 10^(-1)(T/K)2 + 46.18 x 10^(5)(K/T), 310.4 < T(K) < 903.0. Molar heat capacity Cp,m°(T) of Sr2RuO4(s), was derived. The second law method gave the enthalpy of formation of Sr2RuO4(s) from elements in their standard state as ?fH°(Sr2RuO4,s, 298.15K) = -1643.2 kJ mol-1.
A. Banerjee, R. Prasad, V. Venugopal, Journal of Alloys and Compounds 373 (2004) 59-66

B2217 – Magnesium alloys (WE43 and ZE41) characterisation for laser applications

One of the most important parameters in laser treatment is the quantity of beam energy absorbed by the substrate. Despite its important role played in laser processes, this factor is rarely available for the laser sources wavelengths and at high temperatures reached during such treatments. A series of experiments were carried out in order to characterise, from this point of view, two types of magnesium alloys, WE43 and ZE41, often used in laser applications (cladding, alloying, welding, etc.). The results represent an important step in order to understand Mg-alloys behaviour under laser beam action.
S. Ignat, P. Sallamand, D. Grevey, M. Lambertin, Applied Surface Science 233 (2004) 382-391

B2208 – Thermodynamic analysis of the clustering in the Al90Fe7Nb3 alloy

The devitrification of the rapidly quenched Al90Fe7Nb3 alloy was studied by the use of the differential scanning calorimeter, differential thermal analyzer, X-ray difractometer and the transmission electron microscope. The heat capacity of the ribbon was related to that of its master alloy and to the capacities of the Al, Al3Fe and Al3Nb components. The results were interpreted by the two-type cluster model of the alloy structure. The dominant Al-Fe bond is preserved up to 1770 K.
E. Illekova, D. Janickovic, P. Kubecka, P. Svec, J.C. Gachon, Materials Science and Engineering A 375-377 (2004) 946-950

B2207 – Decrystallization in Fe(100-x)Bx system by mechanical alloying

Mechanical alloying technique is used for the decrystallization of Fe(100-x)Bx samples with soft magnetic character. Wide angle X-ray scattering (WAXS) and differential scanning calorimetry have been used to monitor the decrystallization kinetics, whose time dependence can be fitted by a stretched exponential function. In all the samples, milling times of around 500 h lead to very low crystallinity percentages (around 5%). This residual crystalline phase corresponds to a mixture of FeB and Fe2B phases, and the alpha-Fe phase almost disappeared at the same time. During the decrystallization, the grain size of the alpha-Fe phase changes appreciably from 40 down to 15 nm. Magnetic properties of the samples in their final lowest crystalline state showed different behaviours for the samples rich in boron or in iron.
C. Miguel, J.J. del Val, J. Gonzalez, J.M. Gonzalez, Materials Science and Engineering A 375-377 (2004) 849-852

B2206 – Synthesis and crystallisation of Fe61Co7Zr10Mo5W2B15 bulk metallic glasses

This paper focuses on the effects of casting temperature and cooling rate on glass formation of Fe61Co7Zr10Mo5W2B15. The presence of the highly stable ZrB2 crystalline phase in the master alloy allows to obtain a composite (amorphous + ZrB2) directly by casting the liquid phase from a temperature below the liquidus, without preventing glass formation. Incomplete dissolution of ZrB2 causes a reduction of the B content in the amorphous matrix and, consequently, a shift of crystallisation to lower temperatures and a change of the mechanism. The effect of cooling rate on glass formation is clearly visible in a conical bulk sample, where the amorphous fraction decreases as the sample diameter increases from 1 to 3 mm, because of the precipitation of bcc-Fe. Furthermore, nanoindentation experiments show different values of hardness and elastic modulus for the fully amorphous and composite samples.
A. Castellero, M. Motyka, A.L. Greer, M. Baricco, Materials Science and Engineering A 375-377 (2004) 250-254

B2200 – Experimental determination of creep properties of Zirconium alloys together with phase transformation

The temperatures of alpha --> beta transformation for the Zircaloy-4 and Zr-1%NbO alloys were determined using resistivity, calorimetry, image analysis and thermodynamic equilibrium calculations. The experimental and calculated results were found to be in good agreement. The steady state creep behavior was then determined in the single phase and (alpha+beta) phase temperature ranges. Finally, the creep results for both alloys were modeled and summarized into deformation-mechanism maps.
D. Kaddour, S. Frechinet, A.F. Gourgues, J.C. Brachet, L. Portier, A. Pineau, Scripta Materialia 51 (2004) 515-519

B2169 – Formation and phase transition of argyrodite type Ag7TaSe6xS6(1-x) solid solution

The phase relations of Ta-containing argyrodites between Ag7TaS6 and Ag7TaSe6 have been examined by sealed silica tube method at 873 K. Formation of the cubic solid solution Ag7TaSe6xS6(1-x) was confirmed in all the composition range where F43m and P21 3 phases exist in the range of 0 < x < 0.93 and 0.95 < x < 1, respectively. The lattice parameter of mixed crystals obeys the Vegard's rule. It varies linearly from 10.51 to 10.83 Å. The phase transition has been studied by in situ X-ray powder diffraction and DSC measurements. It was found that Ag7TaSe6 and Ag7TaS6 transform to the fcc-high temperature form above 324K and to the monoclinic low temperature one below 250 K, respectively. The transition temperature of the mixed crystals decreases monotonously in a V-shape on going from both the end members to the middle composition Ag7TaS3Se3.
H. Wada, M. Onoda, M. Ishii, A. Sato, M. Tansho, N. Iyi, Journal of Alloys and Compounds 383 (2004) 144-147

B2163 – Thermodynamic analysis and assessment of the Ce-Ni system

An optimised set of thermodynamic parameters for the Ce-Ni system has been obtained using the CALPHAD approach. A thorough thermodynamic analysis of the system has been carried out using different calorimetric techniques and the data have been used in the assessment. The free energy of the liquid phase has been described as a function of temperature and composition using a Redlich-Kister polynomial. Solid compounds have been considered as stoichiometric with the exception of the Laves phases. The phase diagram and thermodynamic quantities calculated from assessed parameters agree well with experimental data.
M. Palumbo, G. Borzone, S. Delsante, N. Parodi, G. Cacciamani, R. Ferro, L. Battezzati, M. Baricco, Intermetallics 12 (2004) 1367-1372

B2159 – Experimental study and thermodynamic re-assessment of the Al-B system

Controversial thermodynamic data in previous assessments of the Al-B system were used to identify a key experiment regarding the enthalpy of formation of AlB2 and its peritectic decomposition temperature. Experiments were performed using AlB2 powder purified by vacuum sublimation. Differential scanning calorimetry (DSC) in a heat-flux twin cylindrical Calvet-type calorimetric system was utilized to measure the enthalpy of decomposition and the reaction temperatures. Samples were characterized by X-ray powder diffraction (XRD). Based on that, a comprehensive and consistent re-assessment of the Al-B system was performed. The incongruent melting of AlB2 occurs at 972°C and a eutectoid decomposition of AlB2 at 213°C is predicted from the thermodynamic description. The present enthalpy data are supported by realistic values of absolute entropies of solid Al-B phases. The formation of AlB2 was never observed on cooling, it is extremely sluggish. Upon heating AlB2, the peritectic reaction does not produce perfectly crystalline AlB12. Based on that and constraints in the thermodynamic data, it is derived that the stability range of AlB2 in equilibrium with perfect crystalline AlB12 may be even more narrow than 972-213°C.
D. Mirkovic, J. Gröbner, R. Schmid-Fetzer, O. Fabrichnaya, H.L. Lukas, Journal of Alloys and Compounds 384 (2004) 168-174

B2157 – Kinetics of iron oxidation in silicate melts: a preliminary XANES study

X-ray Absorption Near Edge Structure (XANES) experiments made between 600 and 700°C at the Fe K-edge have been used to study the kinetics of iron oxidation in a supercooled melt of Fe-bearing pyroxene composition. To provide a firmer basis to redox determinations, the redox state of a series of samples was first determined from wet chemical, Mfssbauer spectroscopy and electron microprobe analyses. The XANES experiments show that variations in relative abundances of ferric and ferrous iron can be determined in situ, even just above the glass transition, and that some information can also be obtained on the structural environment around iron cations. The kinetics of iron oxidation do not vary much with temperature down to the glass transition. This observation suggests that the rate-limiting factor in this process is not oxygen diffusion, which is coupled to relaxation of the silicate network, but, as described by Cooper and coworkers, diffusion of network modifying cations along with a counter flux of electrons.
V. Magnien, D.R. Neuville, L. Cormier, B.O. Mysen, V. Briois, S. Belin, O. Pinet, P. Richet, Chemical Geology 213 (2004) 253- 263

B2155 – Phase transformation in CuAgSe: a DSC and electron diffraction examination

The phase transformation of CuAgSe is examined by DSC and electron diffraction methods. It is found that the transformation occurs at the onset temperature of about 201.8 ± 0.2°C and it is followed by a remarkable hysteresis between heating and cooling. The electron diffraction patterns indicate an orthorhombic superstructure at room temperature. By heating above the transition temperature fcc structure appears. A remarkable short range order, however, persists in this temperature range.
K. Chrissafis, N. Vouroutzis, K.M. Paraskevopoulos, N. Frangis, C. Manolikas, Journal of Alloys and Compounds 385 (2004) 169-172

B2132 – The binary system In-Ir: a new investigation of phase relationships, crystal structures, and enthalpies of mixing

The In-Ir phase diagram was investigated by means of X-ray diffraction, electron probe microanalysis and thermal analysis. The existence of the two intermetallic compounds In3Ir and In2Ir was confirmed, and it was found, that In3Ir transforms into a low-temperature modification In3Ir-LT (CFe3-type structure, oP16, Pnma) at temperatures below about 350°C. The peritectic decomposition reaction of In3Ir and In2Ir at 981°C and 1188°C, resp., was confirmed. There are no indications of a liquid miscibility gap as suggested earlier in the literature. On the other hand, some of the experimental results point to the existence of a metastable high-temperature phase In54Ir46. Enthalpies of mixing were determined by high-temperature drop-calorimetry between 1190 and 1390°C. The minimum in the extrapolated enthalpy of mixing curve is about -18 kJ mol-1 at a composition slightly above x(Ir) = 0.5.
H. Flandorfer, K.W. Richter, E. Hayer, H. Ipser, G. Borzone, J-P. Bros, Journal of Alloys and Compounds 345 (2002) 130-139

B2127 – Thermodynamic properties of germanium and lead tellurites

The temperature dependence of the molar heat capacities of the tellurites PbTeO3, Pb2Te3O8 and Ge(TeO3)2 are determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding compounds showing this dependence are determined using the least-squares method. These equations and the standard molar entropies are used to determine the thermodynamic functions ?Sm°, ?Hm° and (?m° + ?Hm°/T) T=298.15 K.
G. Gospodinov and L. Atanasova, Journal of Thermal Analysis and Calorimetry 87 (2007) 557-559

B2122 – DSC analysis of the precipitation reactions in the alloy AA6082 – Effect of sample preparation

The deformation introduced during the sample preparation had a high impact on the response of the alloy AA6082 to heating in the DSC cell. The DSC curve was strikingly different when DSC samples of this alloy were punched after the solution treatment. Dislocations introduced by punching have annihilated the quenched-in vacancies and have suppressed clustering initially. Dislocations have also provided heterogeneous nucleation sites for the GP-1 zones that readily grew to become stable nuclei for the beta" phase owing to the enhanced atomic transport. beta" as well as the beta' precipitation kinetics were thus accelerated leading to a substantial change in the DSC peak arrangement. Deformation introduced during sample preparation by gentle grinding alone, on the other hand, did not suffice to alter the precipitation sequence, producing a DSC curve very similar to that obtained with samples punched before the solution treatment.
Y. Birol, Journal of Thermal Analysis and Calorimetry 83 (2006) 219-222

B2119 – Effect of ageing on the martensitic transformation of Ni-Fe-Ga alloys

Three polycrystalline Ni(53.5+x)-Fe(19.5-x)-Ga27.0 alloys, with x = 0, 0.5, 1.5, have been aged at 520, 670 and 770 K. All the alloys show good long-term thermal stability after treatments at 520 K, whereas ageing at 670 and 770 K causes degradation of the martensitic transformation after ~10^5-10^6 s, which is more intense in the alloy with lower Fe content. Transmission electron microscopy reveals the appearance of small and mostly elongated precipitates after long ageing periods at 670 and 770 K, associated with a drop of temperatures and heat of transformation measured by differential scanning calorimetry.
R. Santamarta, J. Font, J. Muntasell, F. Masdeu, J. Pons, E. Cesari, J. Dutkiewicz, Scripta Materialia 54 (2006) 1105-1109

B2118 – Effect of microalloying on glass-forming ability and crystallization kinetics of Zr52.5Cu17.9Ni14.6Al10Ti5 alloy

Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass prepared using sponge zirconium was microalloyed with 0.1 at.%B + 0.2 at.%- Si + 0.1 at.%Pb. The effect of microalloying on the glass-forming ability and thermal stability of the alloy is studied. The crystallization kinetic parameters are determined by means of a Kissinger plot. The interrelation between these parameters is discussed.
L. He, J. Sun, Scripta Materialia 54 (2006) 1081-1085

B2114 – Phase equilibria in the binary Rh-Ti system

The present study of the binary Ti-Rh system provides a revised phase diagram clarifying controversial results in the literature. Various experimental methods were applied: electron probe microanalysis, X-ray diffraction, and differential scanning calorimetry. The tie-lines of two-phase equilibria and the second-order transition A2/B2 were identified by means of diffusion couple experiments and by analysis of annealed bulk alloys. The diffusion couple experiments revealed two phenomena which were identified as pseudo-interfaces: one associated with crossing the stoichiometric composition of the B2 phase; a second between pure Rh and the Rh-rich solution.
J. Balun, G. Inden, Intermetallics 14 (2006) 260-271

B2110 – Assessment of the thermodynamic properties and phase diagram of the Bi-Pd system

New experimental DTA, XRD, SEM, solution calorimetry and ab initio calculated results are used together with data from the literature to assess the thermodynamic parameters of the Bi-Pd system, necessary for calculation of the phase diagram by the CALPHAD method. Samples were prepared with compositions of 51and 82 at.% Pd, and their homogeneity checked by SEM/EDX before being employed in DTA studies. High temperature solution calorimetry was used for the determination of the enthalpies of mixing of liquid Pd and Bi, in the range from 0 up to 50 at.% Pd at 1028 K. XRD determination of the structures of equilibrated samples after quenching to room temperature provided important information for the evaluation of structure. Ab initio electronic structure calculations provided information on the energetics of the intermetallic phases of the system. The calculated phase diagram was compared with new phase equilibrium data and with the data presented in the literature.
J. Vrest'al, J. Pinkas, A. Watson, A. Scott, J. Houserova, A. Kroupa, Computer Coupling of Phase Diagrams and Thermochemistry 30 (2006) 14-17

B2100 – Synthesis based on the wet impregnation method and characterization of iron and iron oxide-silica nanocomposites

The present work describes an easy procedure for the preparation of iron-silica and iron oxide-silica composites using the wet impregnation method and subsequent heat treatment in different atmospheres. In this way, a specific composite can be produced with a high content of iron or an iron oxide phase (about 24wt.%) uniformly dispersed in the silica matrix. No pre-treatment before calcinations was necessary to obtain the magnetic phases. Material characterization is also reported.
M.D. Alcala, C. Real, Solid State Ionics 177 (2006) 955-960

B2090 – Phase equilibria and solidification of Mg-rich Mg-Al-Zn alloys

Phase equilibria in Mg-rich corner of Mg-Al-Zn system are analyzed in detail. Thermodynamic calculations are compared with literature data and own key experimental results by means of DSC and DTA measurements. The detailed comparison strongly supports the reliability of the selected thermodynamic description. Furthermore, our focus is placed on proper interpretation of experimental results obtained by thermal analysis. Based on thermodynamic calculation, it is clarified that a signal observed in thermal analysis, which was interpreted as end of solidification in the literature, is related to the start of the monovariant eutectic reaction L + (Mg) + gamma-Mg17Al12 under non-equilibrium condition and the solidification process ends at lower temperature. This fact is supported by our microstructural observation.
M. Ohno, D. Mirkovic, R. Schmid-Fetzer, Materials Science and Engineering A 421 (2006) 328-337

B2086 – Study of the textural evolution in Ti-rich NiTi using synchrotron radiation

The aim of the present work is to investigate the textural evolution in high-temperature phase (austenite - B2) of Ti-rich NiTi (Ni-51at%Ti) shape memory alloys (SMA). The alloy was subjected to different thermomechanical treatments involving various heat treatments and cold rollings (10% and 40%). The qualitative texture analysis was performed at BM20 (ROBL-CRG) of the European Synchrotron Research Facility (ESRF) using in-situ high-temperature X-ray diffraction (XRD) with a wavelength of 0.154 nm. In-situ high-temperature texture determination has been carried out for the first time for Ni-Ti alloys, by annealing at different temperatures up to 800°C under a vacuum better than 10^(-4) Pa. The discussion highlights the evolution of texture during annealing at high temperatures and the change in the coherency domain size and microstrain.
A.S. Paula, J.H.P.G. Canejo, K.K. Mahesh, R.J.C. Silva, F.M. Braz Fernandes, R.M.S. Martins, A.M.A. Cardoso, N. Schell, Nuclear Instruments and Methods in Physics Research B 246 (2006) 206-210

B2081 – Differential calorimetric analysis of the binary system Sb-Zn

The experimental study of the system Sb-Zn by differential calorimetry made it possible to plot the whole phase diagram.We found the stability domains of existence of the stoichiometric compound SbZn and the solid solutions which extend on both sides from the compositions corresponding to Sb3Zn4 (forms gamma and beta) and Sb2Zn3 (forms eta and zeta). Sb3Zn4 and Sb2Zn3 are both congruent melting compounds at 566 and 568°C respectively with an eutectic transformation at 563°C: liquid(43% Zn) <=> Sb3Zn4(gamma) + Sb2Zn3(eta). Sb2Zn3(zeta) is formed at 407°C starting from Sb3Zn4(beta) and zinc. The decomposition, by cooling, occurs around 360°C.
F. Adjadj, E-d. Belbacha, M. Bouharkat, Journal of Alloys and Compounds 430 (2007) 85-91

B2079 – Restoration of the bake hardening response in a naturally aged twin-roll cast AlMgSi automotive sheet

Reversion treatments at 225°C for several minutes were effective in improving the bake hardening response of the naturally aged twin-roll cast AlMgSi sheet which, when processed without reversion, failed to meet in-service strength requirements with a rather poor bake hardening response.
Y. Birol, Scripta Materialia 54 (2006) 2003-2008

B2078 – Effect of atomic order on the martensitic transformation of Ni-Fe-Ga alloys

The effect of atomic order on martensitic transformation (MT) temperatures has been studied by differential scanning calorimetry in three polycrystalline alloys with compositions Ni(53.5+x)-Fe(19.5-x)-Ga27.0 (x = 0, 0.5 and 1.5). Samples water quenched from different temperatures (470-1070 K) exhibit higher MT temperatures than ones slow cooled from the same temperature. This effect has been ascribed to a decrease of the L21 degree of order of the austenitic phase, which promotes an increase in the MT temperatures in these Ni-Fe-Ga alloys. The differences in ordering with cooling rate have been qualitative confirmed by electron diffraction patterns.
R. Santamarta, E. Cesari, J. Font, J. Muntasell, J. Pons, J. Dutkiewicz, Scripta Materialia 54 (2006) 1985-1989

B2074 – Experimental study of the CeNi5-CeCu5 system

The Ce(Ni(1-x)Cux)5 system has been studied by X-ray diffraction, DTA, aluminium drop solution calorimetry, optical and electron microscopy coupled to an EDX analysis system. The existence of a continuous, ideal solid solution Ce(Ni(1-x)Cux)5 has been confirmed and a temperaturecomposition section is given. In addition, it was found that a Ni solubility exists in the solid solution shifting the composition to the Ce-poor direction. No extended Cu solubility has been observed.
J. Wang, J.L. Jorda, A. Pisch, R. Flükiger, Intermetallics 14 (2006) 695-701

B2069 – The isothermal section at 500°C of the Gd-Tb-Ga ternary system

Phase equilibria in the Gd-Tb-Ga ternary system at 500°C were investigated by X-ray powder diffraction and differential scanning calorimetry. The binary compounds, Gd5Ga3, Gd3Ga2, GdGa, GdGa2, Tb5Ga3, TbGa, TbGa2 and TbGa3 have been confirmed at 500°C. No ternary compound was found in this system. The isothermal section of this system at 500°C was constructed. It is composed of 7 single-phase regions, 8 two-phase regions and 2 three-phase regions. Four ternary continuous solid solutions, (Gd, Tb), (Gd, Tb)5Ga3, (Gd, Tb)Ga, (Gd, Tb)Ga2 were formed in this isothermal section. The maximum solid solubilities of Ga in (Gd, Tb) at 500°C is 5.0 at.%. The homogeneity range of (Gd, Tb)Ga2 is from 20 to 33.3 at.% Ga in Gd-Ga side but limited in Tb-Ga side. The solid solubilities of Ga in the other phases cannot be detected. The Curie temperatures of the Gd0.6Tb(0.4-x)Gax alloys increase from 270 to 298K as x increases from 0 to 0.03.
J.Q. Li, Y.X. Jian, W.Q. Ao, Y.H. Zhuang, W. He, Journal of Alloys and Compounds 416 (2006) 160-163

B2067 – The formation of gamma-TiAl from Ti/Al multilayers with different periods

In this paper multilayer thin films with periods (?) ranging from 4 to 1000 nm are studied in order to determine the maximum period leading to the gamma-TiAl phase. The production of high period multilayers (?>20 nm) requires the use of Ti and Al targets one by one. The influence of silver on the thin films transformation Ti/Al multilayer => gamma-TiAl is also analysed. The introduction of a few percent of silver was performed by superimposing small Ag foils on the targets. The kinetics of the phase transformation was studied by differential scanning calorimetry and X-ray diffraction. Up to ?=200 nm, heat treating at 600°C during 1 h leads to gamma-TiAl, with or without small amounts of alpha2-Ti3Al, while for ?=500 and 1000 nm the presence of extra Al-rich phases is detected. For high periods (200, 500 and 1000 nm) an Al3Ti intermediate phase is formed. In the presence of silver the peak temperatures are shifted to lower values and the activation energy values slightly decrease.
A.S. Ramos, R. Calinas, M.T. Vieira, Surface & Coatings Technology 200 (2006) 6196-6200

B2051 – Structural evolution of rapidly solidified Al-Mn and Al-Mn-Sr alloys

In the present paper, microstructure, phase composition and elevated temperature behaviour of two rapidly solidified (RS) Al-5.0 wt.% Mn and Al-4.6 wt.% Mn-2.1 wt.% Sr melt spun ribbons are described. The RS binary alloy was composed of supersaturated alpha-Al solid solution and finely dispersed spheroids of quasi-crystalline icosahedral I-Al6Mn phase. The Sr-addition led to a reduction of volume fraction of the I-Al6Mn phase. Manganese was more concentrated in stable tetragonal beta-Al4Sr phase. DSC measurements revealed exothermal reactions between 400 and 500°C which were more pronounced in the binary Al-Mn alloy. This proved a higher degree of metastability of the binary alloy. The solid state phase transformations included: 1. Decomposition of the supersaturated alpha-Al solid solution. 2. Polymorphous transformation of the quasi-crystalline icosahedral I-Al6Mn phase to a stable orthorhombic O-Al6Mn phase. The decomposition of the supersaturated solid solution produced finely dispersed O-Al6Mn precipitates which induced some hardening of both alloys after pre-annealing at 350°C/5 h.
D. Vojtech, K. Saksl, J. Verner, B. Bartova, Materials Science and Engineering A 428 (2006) 188-195

B2049 – Phase equilibria in the Gd-Bi-Sb ternary system at room temperature

Phase equilibria were established in the Gd-Bi-Sb ternary system at room temperature based on X-ray powder diffraction and differential scanning calorimetry analysis. The binary compounds: Gd5Sb3, Gd4Sb3, GdSb, Gd16Sb39, Gd5Bi3, Gd4Bi3 and GdBi have been confirmed at room temperature. No ternary compound was found in this system. The isothermal section of this system at room temperature consists of six single-phase regions, six two-phase regions and one three-phase regions. Four ternary continuous solid solutions: (Sb, Bi, Gd), Gd(Sb, Bi), Gd4(Sb, Bi)3, Gd5(Sb, Bi)3 were formed in this isothermal section. The binary compounds GdBi2 does not exist in the Gd-Bi phase diagram. The maximum solid solubility of Gd in (Sb, Bi) at room temperature is 7.5 at.%, while the solid solubility of Gd in the other solid solubility are non-observable.
Y.X. Jian, J.Q. Li, F.S. Liu, W.Q. Ao, Journal of Alloys and Compounds 433 (2007) 125-128

B2038 – Experimental investigation of the Mg-Al-Ca system

This work focuses on the experimental investigation of the ternary Mg-Al-Ca system using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and metallographic techniques. DSC has permitted real time measurement of the temperature and enthalpy of the phase transformations. One of the invariant transformations predicted by thermodynamic modeling was verified experimentally and found to occur at 513°C with composition close to 10.8 at.% Ca, 79.5 at.% Mg and 9.7 at.% Al. Three binary compounds are found to have an extended solid solubility into the ternary system: (Mg2Ca) where Al substitute Mg in the binary compound Mg2Ca, (Al2Ca) and (Al3Ca8) where Mg substitute Al in the binary compounds Al2Ca and Al3Ca8, respectively. Two morphologies of eutectic structure were observed in the micrographs and supported by solidification curves; a coarse and fine eutectic microstructures due to the existence of Al2Ca and Mg2Ca, respectively.
M. Aljarrah, M. Medraj, X. Wang, E. Essadiqi, A. Muntasar, G. Dénès, Journal of Alloys and Compounds 436 (2007) 131-141

B2034 – Reply to comments on ‘Incomplete transformation induced multiple-step transformation in TiNi shape memory alloys’

The discussion is focused on clarifying whether there is temperature memory effect (TME) in the R-phase to parent phase transformation in TiNi shape memory alloys. The authors prove that the TME dose occurs. However, the TME in this transformation is much weaker than that in the martensite to parent transformation. In some cases, it needs many repetitions to observe TME in this transformation.
Z.G. Wang, X.T. Zu, H.J. Yu and H. Fu, Scripta Materialia 55 (2006) 497-500

B2032 – Liquidus and solidus temperatures of Mg-rich Mg-Al-Mn-Zn alloys

The phase equilibria and solidification process for Mg-rich Mg-Al-Mn-Zn alloys are analyzed based on a combination of computational thermochemistry and differential thermal analysis and differential scanning calorimetry measurements. Our main concern is the proper interpretation of the experimental results of thermal analysis. For a wide range of Mg-rich alloys it is demonstrated that: (i) the high-temperature signal does not represent the actual liquidus temperature and this signal is related to the phase boundary, L + Al8Mn5/L + Al8Mn5 + (Mg); and (ii) the low-temperature signal in thermal analysis is associated not with the end of the solidifi- cation process but with the precipitation of gamma-Mg17Al12 phase under the Scheil condition. In addition, we demonstrate that the actual solidification temperature, either at a slow cooling rate (1 K/min) or in casting, is virtually identical to the incipient melting temperature of as-cast alloys during subsequent heating.
M. Ohno, D. Mirkovic, R. Schmid-Fetzer, Acta Materialia 54 (2006) 3883-3891

B2031 – Liquidus and solidus temperatures of Mg-rich Mg-Al-Mn-Zn alloys

The phase equilibria and solidification process for Mg-rich Mg-Al-Mn-Zn alloys are analyzed based on a combination of computational thermochemistry and differential thermal analysis and differential scanning calorimetry measurements. Our main concern is the proper interpretation of the experimental results of thermal analysis. For a wide range of Mg-rich alloys it is demonstrated that: (i) the high-temperature signal does not represent the actual liquidus temperature and this signal is related to the phase boundary, L + Al8Mn5/L + Al8Mn5 + (Mg); and (ii) the low-temperature signal in thermal analysis is associated not with the end of the solidifi- cation process but with the precipitation of gamma-Mg17Al12 phase under the Scheil condition. In addition, we demonstrate that the actual solidification temperature, either at a slow cooling rate (1 K/min) or in casting, is virtually identical to the incipient melting temperature of as-cast alloys during subsequent heating.
M. Ohno, D. Mirkovic, R. Schmid-Fetzer, Acta Materialia 54 (2006) 3883-3891

B2021 – Study of crystallization processes in Gd-substituted Finemet alloys

The crystallization processes that occur in amorphous melt-spun ribbons of nominal composition Fe73.5Cu1Nb3Si13.5B9 with Gd addition in different concentrations are studied by differential scanning calorimetry (DSC). The aim of Gd addition is to study the changes induced in the calorimetric behavior of Finemet alloys, the crystallization sequences at intermediate stages of annealing as well as the nature of obtained crystallization products. The nature and structural properties of the phases formed at the end of the calorimetric process are investigated using X-ray diffraction (XRD) and Mössbauer spectrometry (MS). The crystallization sequence and also the phase composition at different stages of annealing were investigated for the Fe68.5Gd5Cu1Nb3Si13.5B9 alloy. Structure and magnetic properties of resulting crystallized samples have been thoroughly investigated. It is shown that in the above-mentioned composition, the decomposition at around 690°C of the metastable Gd3Fe62B14 phase formed at incipient stages of crystallization leads to the co-existence of Gd2Fe14B, Fe2B and alpha-Fe(Si) phases. Magnetic measurements of as-cast and annealed samples are in good agreement with the XRD and MS results and with the proposed crystallization sequences and decomposition of intermediate metastable phases.
O. Crisan, J.M. Le Breton, A.D. Crisan, G. Filoti, Journal of Alloys and Compounds 422 (2006) 194-202

B2017 – Nanometric multilayers: A new approach for joining TiAl

A novel intermetallic alloy diffusion bonding procedure is being developed. The innovative aspect relies on the use of sputtered nanometallic multilayers made up of the elements present in the bulk intermetallics to enhance the bonding mechanisms. For this purpose a deep knowledge of the multilayer thin films is required, focusing on thermal phase stability and grain size evolution. gamma-TiAl was selected for this study and Ti/Al multilayer thin films with nanometric period (Lambda = 4 nm) were deposited onto Ti-(45-49)Al-(3-2)Nb-2Cr (at.%) substrates by d.c. magnetron sputtering. The as-deposited titanium and aluminium nanolayers with crystallite sizes of 5e50 nm evolve toward the equilibrium gamma-TiAl structure after heat treatment for at least up to 600°C at a 10°C min-1 heating rate. Whatever the heating temperature and holding time, between 600 and 1000°C, the gamma-TiAl phase is stable. During the thermal cycle the growth of the nanometric grains is promoted, this effect being more pronounced as the temperature and holding time increase. Consequently, the hardness decreases from 11.9 GPa (600°C, 1 h) to 6.5 GPa (1000°C, 3 h). This study allowed the thermal treatment required to join gamma-TiAl parts to be established.
A.S. Ramos, M.T. Vieira, L.I. Duarte, M.F. Vieira, F. Viana, R. Calinas, Intermetallics 14 (2006) 1157-1162

B2008 – Influence of initial phase composition on glass-forming ability of Co-based alloys

The glass-forming ability depending on initial phase composition of soft-magnetic Co70Fe2Mn4Si14B9Mo1 and Co68Cr3Fe3B12Si14 alloys has been studied. It was found that granules of Co70Fe2Mn4Si14B9Mo1 alloy have the best glass-forming ability which allows to use these granules as a crystal precursor of amorphous state, which is prone to rapid amorphization with minimum energy consumption both on quenching alloy and on mechanical processing in a ball mill.
E.A. Chikina, N.P. Dyakonova, V.V. Molokanov, T.A. Sviridova, Journal of Alloys and Compounds 434-435 (2007) 394-399

B2001 – The liquid metastable miscibility gap in Cu-based systems

Some Cu-based alloys, like Cu-Co, Cu-Fe and Cu-Co-Fe, display a liquid metastable miscibility gap. When the melt is undercooled below a certain temperature depending on the alloy composition, they present a separation in two liquid phases, followed by coagulation before dendritic solidification. In order to predict the phase equilibria and the mechanisms of microstructure formation, a determination of the metastable monotectics in the phase diagrams is essential. This paper focuses on the up-to-date findings on the Cu-Co, Cu-Fe and Cu-Co-Fe metastable miscibility gap in the liquid phase. Furthermore, the knowledge on the phase equilibria in the three systems is extended by presenting new results obtained by differential scanning calorimetry (DSC) and comparing them with the calculated phase diagrams.
S. Curiotto, R. Greco, N.H. Pryds, E. Johnson, L. Battezzati, Fluid Phase Equilibria 256 (2007) 132-136

B1998 – Experimental study and thermodynamic calculation of Al-Mg-Sr phase equilibria

Selected samples of ternary Al-Mg-Sr alloys were investigated using thermal analysis, scanning electron microscopy and electron microprobe analysis. Additional samples, prepared in Montreal, were re-evaluated by simulation of their X-ray diffraction spectra and by careful analysis of their thermal analysis signal curves. A comprehensive and consistent thermodynamic description for the ternary Al-Mg-Sr system is generated by assessing all experimental data from the literature combined with the present experimental results. Extended ternary solid solubilities of binary phases and one ternary intermetallic phase are established in this system. Calculated phase diagram sections and the liquidus surface together with thermodynamic equilibrium and non-equilibrium Scheil calculations of selected alloys are used to demonstrate the good agreement with all of the experimental microstructures. This provides additional support for the thermodynamic description generated in this work.
A. Janz, J. Gröbner, D. Mirkovic, M. Medraj, Jun Zhu, Y.A. Chang, R. Schmid-Fetzer, Intermetallics 15 (2007) 506-519

B1997 – Characterization of crystallization kinetics of a Ni- (Cr, Fe, Si, B, C, P) based amorphous brazing alloy by non-isothermal differential scanning calorimetry

The thermal stability and crystallization kinetics of a Ni- (Cr, Si, Fe, B, C, P) based amorphous brazing foil have been investigated by nonisothermal differential scanning calorimetry. The glass transition temperature Tg, is found to be 720±2K. The amorphous alloy showed three distinct, yet considerably overlapping crystallization transformations with peak crystallization temperatures centered around 739, 778 and 853±2K, respectively. The solidus and liquidus temperatures are estimated to be 1250 and 1300±2K, respectively. The apparent activation energies for the three crystallization reactions have been determined using model free isoconversional methods. The typical values for the three crystallization reactions are: 334, 433 and 468 kJ mol-1, respectively. The X-ray diffraction of the crystallized foil revealed the presence of following compounds Ni3B (Ni4B3), CrB, B2Fe15Si3, CrSi2, and Ni4.5Si2B.
S. Raju, N.S. Arun Kumar, B. Jeyaganesh, E. Mohandas, U. Kamachi Mudali, Journal of Alloys and Compounds 440 (2007) 173-177

B1995 – Glass formation and magnetic characterization of (Fe78B14Si8)-Nb-Y alloys

In the present work, the glass formation of Fe78B14Si8 alloy with small additions of Nb and Y has been investigated. Ribbons were prepared by planar-flow casting. Small ingots (up to 5mm in diameter) were obtained by injection casting technique into a conical Cu mold. Thermal and structural properties were measured using differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. The microstructure has been observed by scanning electron microscopy (SEM). Quasi-static hysteresis loops have been measured using a vibrating sample magnetometer (VSM). Rapid solidification leads to a fully amorphous structure for all compositions. A partial amorphous structure has been obtained in samples prepared by copper mold casting, when adding Nb and Y. The role of Nb and Y addition on glass formation is discussed on the basis of melting behavior, analyzed by HT-DSC. Magnetic properties are correlated with the observed microstructures.
R. Piccin, P. Tiberto, M. Baricco, Journal of Alloys and Compounds 434-435 (2007) 628-632

B1990 – Wetting behaviour and reactivity of lead free Au-In-Sn and Bi-In-Sn alloys on copper substrates

The main objective of this work is to determine the wetting behaviour of lead-free solders on copper substrates in view of their applications in electronic industry. The wetting behaviour of X-In-Sn (X = Au, Bi) ternary molten alloys in contact with copper has been studied and compared with the corresponding behaviour of their binary subsystems with a particular attention to the In-Sn/Cu system. The contact angle measurements on Cu-plates were performed by using a sessile drop apparatus. The solder/copper interface was characterised by the SEM-EDS analysis.
F. Gnecco, E. Ricci, S. Amore, D. Giuranno, G. Borzone, G. Zanicchi, R. Novakovic, International Journal of Adhesion & Adhesives 27 (2007) 409-416

B1965 – Enthalpies of formation of Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 intermetallic compounds

Cadmium is expected to be the solvent for pyrochemical processing of the metallic nuclear fuel. Therefore, thermodynamic properties of cadmium with various fuel and clad elements are of interest. Enthalpies of formation of the intermetallic compounds of Cd-Sr system, Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 were determined by precipitation using Calvet calorimeter. Enthalpies of formation of the compounds were found to be -3.05±0.5 kJ mol-1 at 723 K, -14.2±0.7 kJ mol-1 at 843K and -28.4±0.8 kJ mol-1 at 863 K, respectively. Enthalpies of formation of Cd0.917Sr0.083 and Cd0.857Sr0.143 were also determined by partial enthalpy of formation measurements and the values were found to be -3.9±1.1 kJ mol-1 at 723K and -13.42±1.2 kJ mol-1 at 843 K, respectively. Miedema model was used to estimate the enthalpies of formation of these compounds and the estimated values were compared with the experimentally determined values.
R. Agarwal, Z. Singh, Journal of Alloys and Compounds xxx (2007) xxx-xxx

B1960 – Effect of ageing in Ni-Fe-Ga ferromagnetic shape memory alloys

Three polycrystalline Ni(53.5+x)-Fe(19.5-x)-Ga27.0 alloys, with x = 0, 0.5, 1.5 (at.%), have been aged at 520 and 670 K. The initial increase of martensitic transformation temperatures upon ageing has been attributed to a decrease of L21 order. The alloys with lower Fe content show remarkable thermal stability for ageing times larger than 10^7 s at 520 K. In the case of ageing at 670 K, degradation of the alloys occurs after ~10^6 s. Optical and transmission electron microscopy reveal the initial presence of gamma' particles mostly located at the grain boundaries, as well as the appearance of small (<1µm) elongated precipitates after long ageing periods at 670 K, associated to a drop of transformation temperatures.
J. Font, J. Muntasell, R. Santamarta, F. Masdeu, J. Pons, E. Cesari, C. Segui, J. Dutkiewicz, Materials Science and Engineering A 438-440 (2006) 919-922

B1958 – Effect of high magnetic field on the coercivity in sintered Nd-Fe-B magnets

An influence of a 140 kOe magnetic field applied during the last-stage annealing process was investigated in Dy-free Nd-Fe-B sintered magnets. When a sample containing small amount of Cu and Al was annealed at Ta = 500 and 550°C under a magnetic field of Ha = 140 kOe, the coercivity Hc increased by 20% and 16%, respectively, as compared with the control sample annealed at zero field. DSC data of this sample showed anomalies around 500 and 540°C. These results were discussed in terms of a field-induced change in interface matching between Nd2Fe14B and intergranular phases.
H. Kato, T. Akiya, M. Sagawa, K. Koyama, T. Miyazaki, Journal of Magnetism and Magnetic Materials 310 (2007) 2596-2598

B1945 – Effect of the heating rate on crystallization behavior of mechanically alloyed Mg50Ni50 amorphous alloy

The mechanical alloying is the most convenient method to produce Mg-Ni alloys. In this study, the effect of ball-to-powder weight ratios and the mechanical alloying time on amorphization of Mg50Ni50 alloy and its thermal stabilities were investigated. Mg50Ni50 alloy has been produced by using Spex 8000 D mixer/mill with different ball-to-powder weight ratios (5:1, 10:1, 20:1). Amorphization times by XRD analysis are found to be 60 h for 5:1 ball-to-powder weight ratio, 10 h for 10:1 ball-to-powder weight ratio and 5 h for 20:1 ball-to-powder weight ratio. The thermal stabilities of amorphous Mg50Ni50 alloys, obtained by different ball-to-powder weight ratios, have been determined and the effect of heating rates on the crystallization temperatures have also been investigated by DSC. The heating rates employed were 5, 10, 15, 20°C/min. During the first crystallization reaction, the amorphous and Mg2Ni intermetallic phases occurred. DSC studies show that increase in heating rates increased the crystallization temperatures for all samples. The apparent activation energies were determined by means of the Kissinger method.
N. Aydinbeyli, O.N. Celik, H. Gasan, Kerem Aybar, International Journal of Hydrogen Energy 31 (2006) 2266 - 2273

B1943 – Bismuth activity in lead-free solder Bi-In-Sn alloys

The thermodynamics of Bi-In-Sn lead-free solder alloys has been studied by two different experimental techniques: torsion-effusion and differential scanning calorimetry. The results show that this ternary system at fixed Bi composition, XBi = 0.20, and 565 K behaves as a non-ideal system with exothermic ?mixHT° passing through a minimum at XIn = 0.58 and XSn = 0.22. In the whole range of the quantity XSn/(XSn+XIn) and at 1050 K the average value of the bismuth activity is 0.14 ± 0.02 which implies an average activity coefficient of Bi equal to 0.70 ± 0.01. The Bi activity in ternary alloys at 1000 K with variable XBi and fixed ratio r = XSn/XIn = 0.85 has been measured. The excess integral free energy change for the mixing, ?mixGT° (xs), has also been evaluated by making use of both the torsion-effusion experimental and literature data for Bi-Sn and Bi-In binary systems. Under these conditions, the ternary system is not a regular solution and the entropy contribution to the free energy of mixing is dominating the Gibbs energy.
B. Brunetti, D. Gozzi, M. Iervolino, V. Piacente, G. Zanicchi, N. Parodi, G. Borzone, Computer Coupling of Phase Diagrams and Thermochemistry 30 (2006) 431-442

B1940 – Preparation of CuInSe2 thin films through metal organic chemical vapor deposition method by using di-?-methylselenobis(dimethylindium) and bis (ethylisobutyrylacetato) copper(II) precursors

Highly polycrystalline copper indium diselenide (CuInSe2) thin films on molybdenum substrate were successfully grown at 330°Cthrough two-stage metal organic chemical vapor deposition (MOCVD) method by using two precursors at relatively mild conditions. First, phase pure InSe thin film was prepared on molybdenum substrate by using a single-source precursor, di-?-methylselenobis(dimethylindium). Second, on this InSe/ Mo film, bis(ethylisobutyrylacetato) copper(II) designated as Cu(eiac)2 was treated by MOCVD to produce CuInSe2 films. The thickness and stoichiometry of the product films were found to be easily controlled in this method by adjusting the process conditions. Also, there were no appreciable amounts of carbon and oxygen impurities in the prepared copper indium diselenide films.
S.H. Yoon, K.W. Seo, S.S. Lee, I-W. Shim, Thin Solid Films 515 (2006) 1544-1547

B1939 – Thermal and conductometric studies of the CeBr3-MBr binary systems (M = Li, Na)

DSC was used to investigate phase equilibrium in the CeBr3-MBr (M = Li, Na) systems. They represent typical examples of simple eutectic systems. The eutectic composition and eutectic temperature, x(CeBr3) = 0.249, Teut = 709K and x(CeBr3) = 0.372, Teut = 692 K, were found for CeBr3-LiBr and CeBr3-NaBr systems, respectively. The electrical conductivity of CeBr3-MBr liquid mixtures, together with that of pure components was measured down to temperatures below solidification. Results obtained are discussed in term of possible complex formation.
E. Ingier-Stocka, L. Rycerz, S. Gadzuric, M. Gaune-Escard, Journal of Alloys and Compounds xxx (2007) xxx-xxx

B1938 – Physicochemical properties of the EuBr2-KBr binary system

The phase diagram of the EuBr2-KBr binary system was derived from DSC measurements. It exhibits three eutectics and three stoichiometric compounds. The first compound, K2EuBr4, melts congruently at 834 K. The second one, KEuBr3 undergoes a solid-solid phase transition at 810K and decomposes peritectically at 846 K. The third compound, KEu2Br5, melts congruently at 880 K. The composition of the three eutectic mixtures, x(EuBr2) = 0.318, 0.433 and 0.789, respectively, were determined by the Tamman method. The respective eutectic temperatures are 829, 811 and 854 K. Diffuse reflectance spectra of the pure components and their solid mixtures confirmed the existence of new phases exhibiting their own spectral characteristics, which may be related to the existence of above mentioned compounds in the system under investigation.
L. Rycerz, E. Ingier-Stocka, M. Cieslak-Golonka, A. Wojciechowska, S. Gadzuric, M. Gaune-Escard, Journal of Alloys and Compounds xxx (2007) xxx-xxx

B1929 – Experimental study of the phase diagram of the Ag-Au-Sb ternary system

The phase diagram of the Ag-Au-Sb ternary system has been assessed using X-ray diffraction analysis, electron-probe micro-analysis and differential scanning calorimetry. Four isopletic sections were studied: 80, 70 and 10 at.% Ag and 10 at.% Au. Three ternary invariant reactions were noted. This study is part of an international program, COST 531, about lead-free soldering materials.
E. Zoro, C. Servant, B. Legendre, Journal of Alloys and Compounds 426 (2006) 193-199

B1928 – Experimental study of the phase diagram of the Ag-Au-Sb ternary system

The phase diagram of the Ag-Au-Sb ternary system has been assessed using X-ray diffraction analysis, electron-probe micro-analysis and differential scanning calorimetry. Four isopletic sections were studied: 80, 70 and 10 at.% Ag and 10 at.% Au. Three ternary invariant reactions were noted. This study is part of an international program, COST 531, about lead-free soldering materials.
E. Zoro, C. Servant, B. Legendre, Journal of Alloys and Compounds 426 (2006) 193-199

B1926 – Calorimetric measurements of the ternary Ag-Au-Sn system

Using a Calvet type calorimeter, the enthalpy of mixing in the ternary system Ag-Au-Sn was determined at 873 and at 1023 K. The investigations were carried out at three cross-sections with constant molar ratios of Ag:Sn = 1:1, 1:2, and 1:9 at 873 K, and at four cross-sections with constant molar ratios of Ag:Sn = 2:1, 1:1, 1:2, and 1:9 with Au added in the concentration range between 0 and 55 at.%. The substitutional solution model of Redlich-Kister-Muggianu was used for a least square fit of the experimental data in order to get an analytical expression for the integral enthalpy of mixing. The ternary extrapolation models of Kohler, Muggianu and Toop were used to calculate the integral enthalpy of mixing and to compare measured and extrapolated values.
Z. Li, M. Dallegri, S. Knott, Journal of Alloys and Compounds 453 (2008) 442–447

B1925 – A new investigation of the system Ni-Sn

The system Ni-Sn, being one of the key systems for lead-free soldering, has been the subject of intensive investigations in the 1930s and 1940s. The most recent phase diagram assessment as well as various calculations of this system almost exclusively rely on these data. As the assessment seemed to be based on a rather arbitrary selection of experimental data, a new experimental investigation of this system was considered necessary. In this work a new version of the Ni-Sn system was established following a comprehensive survey of existing literature and the investigation of 27 samples. XRD (including high temperature XRD), DTA, EPMA and metallographic examination were performed on these samples annealed at various temperatures. Especially in the region of Ni3Sn considerable differences to existing phase diagram information were recognized. The crystal structure of the Ni3Sn HT-phase was found to be cubic (BiF3-type) by HT-XRD, and the phase transition was determined to be at higher temperature than reported previously. Furthermore a suggestion for the phase transformation in Ni3Sn2 was included. This region of the system was found to be far more complex than hitherto reported, because of the existence of two further incommensurate Ni3Sn2 lowtemperature modifications first discovered by Leineweber et al.
C. Schmetterer, H. Flandorfer, K.W. Richter, U. Saeed, M. Kauffman, P. Roussel, H. Ipser, Intermetallics 15 (2007) 869-884

B1923 – X-ray diffraction, 119Sn Mössbauer and thermal study of SnSe-Bi2Se3 system

The phase equilibrium diagram of the SnSe-Bi2Se3 system has been re-investigated using X-ray powder diffraction, thermal analysis (DTA and DSC) and 119Sn Mössbauer spectroscopy data. It shows solid solutions based on Bi2Se3 and SnSe ( alpha and beta forms) and three intermediate phases: well-defined, SnBi4Se7, SnBi4Se7, and a new phase Sn2Bi2Se5. The new phase Sn2Bi2Se5 exists in the composition range 25-55 mol% Bi2Se3. Its structure is still under study. However, 119Sn Mössbauer spectroscopy study of the latter allowed to achieve a well knowledge of the local environment of tin atoms and could contribute to the actual structural study.
K. Adouby, M.L. Elidrissi Moubtassim, C.P. Vicente, J.C. Jumas, A.A. Touré, Journal of Alloys and Compounds xxx (2007) xxx-xxx

B1919 – Effects of RE on the microstructure and mechanical properties of Mg-8Zn-4Al magnesium alloy

Effects of rare earth (RE) alloy element on the microstructure and mechanical properties of Mg-8Zn-4Al (ZA84) alloy have been investigated. The differential scanning calorimetry (DSC) technique was used to study the solidification and aging process of ZA84 and ZA84-xRE alloys. The results show that a new quaternary precipitate Mg3Al4Zn2RE forms during the solidification and its phase transformation temperature point is 413°Cin RE-containing ZA84 alloys. The microstructure of ZA84 alloy can be refined, phases formed, microhardness of the matrix increased and time for attaining microhardness peak value of aging ZA84-xRE alloys delayed, with increasing RE. Thus, the room temperature and high temperature tensile properties of as-cast and aged ZA84 alloys can be improved by RE addition.
Y. Wang, S. Guan, X. Zeng, W. Ding, Materials Science and Engineering A 416 (2006) 109-118

B1903 – On the mechanism of formation of zinc pack coatings

The mechanism of the formation of zinc (Zn) pack coatings is studied with scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). DSC showed that the coatings formation takes place in three steps. The initial step (at 193.9°C) is endothermic and involves the transformation of alpha-NH4Cl to beta-NH4Cl and the NH4Cl decomposition to NH3 and HCl. During the second step (at 248.6°C), which is exothermic, Zn2+ salts are formed and especially ZnCl2. Finally at 264.1°C Zn is deposited by an endothermic reaction on the ferrous substrate through the decomposition of ZnCl2. The as-cast Zn diffuses into the iron lattice forming the gamma ( gamme-Fe11Zn40) and delta ( delta-FeZn10) phases. Al2O3 is not involved in the above-mentioned mechanism and acts only as filler.
N. Pistofidis, G. Vourlias, D. Chaliampalias, K. Chrysafis, G. Stergioudis, E.K. Polychroniadis, Journal of Alloys and Compounds 407 (2006) 221-225

B1888 – Role of phase transition in the unusual microwear behavior of superelastic NiTi shape memory alloy

The excellent microwear performance of nano-grained superelastic nickel titanium (NiTi) polycrystalline shape memory alloy (SMA) is reported in this paper. The microwear test was conducted at temperatures ranging from 22 to 120°C by a Hysitron triboindenter. The results showed that the NiTi SMA has superior microwear resistance compared to traditional tribo-materials such as stainless steel AISI 304 and that the material exhibits unusual hardness dependence of wear within certain temperature regimes. With the increase in temperature from 22 to 120°C, wear resistance was found to decrease anomalously with an increase in hardness. Further investigation and analysis confirmed that the stress-induced phase transition during contact and wear play an essential role in the material's high wear resistance. It is demonstrated through contact mechanics analysis that the increase of hardness with temperature was mainly due to the increase in the phase transition stress. The observed applied threshold load that corresponds to the onset of the plastic deformation in the contact area was strongly influenced by the phase transition process at the tip region. For the investigated superelastic NiTi, the temperature-dependent interplay between reversible phase transition and irreversible plastic yielding plays a key role in the temperature dependence of the wear performance and is responsible for the observed apparent unusual hardness-wear relationships.
L. Qian, Q. Sun, X. Xiao, Wear 260 (2006) 509-522

B1886 – High-purity amorphous Zr52.5Cu17.9Ni14.6Al10Ti5 powders via mechanical amorphization of crystalline pre-alloys

Fully amorphous Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit 105) powder with very low oxygen contamination was successfully produced from pre-alloyed crystalline material. A yield of over 80% was achieved without the use of a milling agent. The amorphization process was observed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The extremely fast amorphization rate was fitted by an exponential relaxation function. A partial time-temperature-transformation (TTT) diagram was obtained from isothermal annealing experiments based on the Johnson-Mehl-Avrami (JMA) model. In addition, the microstructure of the powder was observed by scanning electron microscopy (SEM), and gas analysis was conducted at various stages of the ball-milling process.
M.E. Siegrist, M. Siegfried, J.F. Loffler, Materials Science and Engineering A 418 (2006) 236-240

B1863 – Solidification behaviour of bulk glass-forming alloy systems

The solidification behaviour and resultant microstructures of bulk glass forming ferrous (Fe60Co8Zr10Mo5W2B15) and non-ferrous (Zr65Al10Ni10Cu15) alloy systems have been investigated. It was shown that the suppression of the eutectic reaction during solidification ultimately leads to the formation of an amorphous structure. The characteristic DSC pattern of melting involving a sequence of eutectic and peritectic like reactions with a high magnitude of reaction enthalpies ratio ( Hp/ He), appear to be essential parameters for high bulk glass forming ability.
M.V. Akdeniz, A.O. Mekhrabov, M.K. Pehlivanoglu, Journal of Alloys and Compounds 386 (2005) 185-191

B1860 – Study of transformation behavior in a Ti-4.4 Ta-1.9 Nb alloy

An alloy of composition Ti-4.4 wt.% Ta-1.9 wt.% Nb is being developed as a structural material for corrosion applications, as titanium and its alloys possess excellent corrosion resistance in many oxidizing media. The primary physical metallurgy database for the Ti-4.4 wt.% Ta-1.9 wt.% Nb alloy is being presented for the first time. Determination of the beta transus, Ms temperature and classification of the alloy have been carried out, employing a variety of microscopy techniques, X-ray diffraction (XRD), micro-hardness and differential scanning calorimetry (DSC). The beta transition temperature or beta transus determined using different experimental techniques was found to agree very well with evaluations based on empirical calculations. Based on chemistry and observed room temperature microstructure, the alloy has been classified as an alpha + beta titanium alloy. The high temperature beta transforms to either alpha' or alpha + beta by a martensitic or Widmanstatten transformation. The mechanisms of transformation of beta under different conditions and characteristics of different types of alpha have been studied and discussed in this paper.
R. Mythili, V. Thomas Paul, S. Saroja, M. Vijayalakshmi, V.S. Raghunathan, Materials Science and Engineering A 390 (2005) 299-312

B1858 – Pre-aging to improve bake hardening in a twin-roll cast Al-Mg-Si alloy

Heat-treatable Al-Mg-Si aluminum alloys are increasingly used for automotive body panel applications. They are shipped and formed in T4 temper while still formable and are subsequently given a bake cycle to increase strength by age hardening while the paint is cured. The industrial paint-bake treatment, however, is too short to fully exploit the age hardening potential of these alloys. Hence, the microstructure in the conventional T4 temper must be modified by creating clusters that grow and readily transform into coherent precipitates upon paint baking. The present work was undertaken to improve the paint-bake response of a twin-roll cast 6016 sheet by employing artificial aging between the solution treatment and the paint-bake cycle. Pre-aging in a wide temperature range (60-200°C) was effective in improving the bake hardening response of the twin-roll cast 6016 sheet which, when processed without any pre-aging, failed to meet in-service strength requirements with a rather poor bake hardening response of 35MPa.
Y. Birol, Materials Science and Engineering A 391 (2005) 175-180

B1855 – Temperature memory effect induced by incomplete transformation in TiNi shape memory alloy

Temperature memory effect can be induced by incomplete transformation upon either heating or cooling in TiNi shape memory alloys (SMAs). An incomplete cycle on heating (ICH) of shape memory alloy arrested at a temperature between As and Af induce a kinetic stop slight higher than the arrested temperature in the next complete transformation cycle. An incomplete cycle on cooling of a shape memory alloy arrested at a temperature between Ms and Mf induce an increase of the transformation heat of the reverse transformation with a decrease in the arrested temperature in the following heating for a sample without R-phase transformation. And for a sample with R-phase transformation, when the stop temperature arrested in the temperature range between Rf and Ms, the heat flow detected upon following heating only shows one endothermic peak. With decreasing arrested temperature Ts to the temperature range between Ms and Mf, two endothermic peaks can be found upon the following heating. With decreasing arrested temperature Ts the transformation heat of the first peak decreases and that of the second peak increases.
Z.G. Wang, X.T. Zu, S. Zhu, L.M. Wang, Materials Letters 59 (2005) 491- 494

B1854 – Pre-straining to improve the bake hardening response of a twin-roll cast Al-Mg-Si alloy

Twin-roll cast (TRC) Al-Mg-Si sheet samples were pre-strained in tension shortly after the solution treatment. Microhardness, electrical conductivity and differential scanning calorimetry measurements were employed to investigate the effect of a mechanical rather than a thermal treatment on the bake hardening response.
Y. Birol, Scripta Materialia 52 (2005) 169-173

B1853 – On the mechanism of heterogeneous reaction and phase formation in Ti/Al multilayer nanofilms

This article describes results obtained during the study of the combustion syntheses of intermetallic Al-Ti films, starting from elemental nanoscaled multilayers of Al and Ti. The original multilayers were prepared by plasma sputtering and the combustion synthesis was started by local or general heating, depending on the case. Atomic scanning tunneling microscopy, scanning and transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry have been used to study the slow and self propagating reaction modes. Self-sustained reaction starts at temperature 600 K, which is much lower than the value for powder mixtures of similar composition and may be explained by abnormally fast diffusion along grain boundaries. Formation of product "bridges" across the nanolayers was observed at the first stages of the reaction. The combustion product (TiAl) inherits the texture of initial Ti and Al layers. An interpretation of the reaction mechanisms for the formation of TiAl and TiAl3 is given and discussed.
J.-C. Gachon, A.S. Rogachev, H.E. Grigoryan, E.V. Illarionova, J.-J. Kuntz, D.Yu. Kovalev, A.N. Nosyrev, N.V. Sachkova, P.A. Tsygankov, Acta Materialia 53 (2005) 1225-1231

B1846 – The combined role of nickel and boron on the nucleation and growth of Fe-based non-crystalline alloys

Amorphous ribbons of composition Fe(75-x)Ni(x)Si9B16 (x = 1; 2, 3, 4) were in situ crystallized upon heat treatment and electron beam irradiation. Depending on the Ni concentration an eutectic or primary crystallization tookplace. The sequence of phases formation was followed by transmission electron microscopy observations and thermal analysis. Other studies (Scripta Metall. 12 (1978) 75, Appl. Phys. Lett. 33 (1978) 233, RQ 111, 1 (1978) 44428) led to the conclusion that the presence of a supersaturated solid solution of boron in Fe-based amorphous alloys strongly influences the crystallization process. In our case, the onset crystallization is determined by the boron solid solution in iron in the case of Ni content less than 3 wt%, while Ni admixtures more than 4 wt% alter the process of the nucleation and the subsequent crystallization. The last one results in the formation of an ultrafine grain structure composed mainly of alpha-Fe(Si) crystallites. It seems that the modification of the crystallization is a result of the inhibition of the formation of a supersaturated solid solution of boron in iron. An observed large scattering of the values of the lattice parameter of alpha-Fe(Si) crystallites was ascribed to a different degree of occupation of metalloid atoms in the a-Fe grains.
G. Stergioudis, G. Vourlias, N. Pistofidis, K. Chrissafis, E.K. Polychroniadis, Journal of Crystal Growth 275 (2005) e1821-e1825

B1839 – Effects of proton irradiation on transformation behavior of TiNi shape memory alloy thin films

In this work, Ti-49.8 at.% Ni shape memory alloy (SMA) thin films were irradiated by 60-keV protons with two types of doses: 5 1016 and 1 1017 H+/cm2. The influence of proton irradiation on the transformation behavior of TiNi shape memory alloy films was investigated by differential scanning calorimetry (DSC) and glancing-incidence X-ray diffraction (GIXRD). The martensite transformation temperatures and austenite transformation temperatures shifted to lower value after proton irradiation, whereas proton irradiation has little effect on the R-phase transformation temperatures. This observation can be attributed to the formation of hydrides after proton irradiation.
Z.G. Wang, X.T. Zu, Y.Q. Fu, J.H. Wu, H.J. Du, Thin Solid Films 474 (2005) 322- 325

B1827 – Mechanical alloying of Fe-Ni based nanostructured magnetic materials

Alloys with the composition Fe40Ni38B18Mo4, Fe49Ni46Mo5 and Fe42Ni40B18 were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe3B phase formed in the Fe42Ni40B18 alloy while no boride phase formed in the Fe40Ni38B18Mo4 alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe40Ni38B18Mo4 and Fe42Ni40B18 alloys. A two-stage crystallization process was found in the Fe40Ni38B18Mo4 and Fe42Ni40B18 alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe40Ni38B18Mo4 and Fe42Ni40B18 alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe40Ni38B18Mo4 alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the Ms of heat-treated Fe42Ni40B18 alloy milled for 100 h decreased and the Hc increased. This difference in magnetic behavior is due to the alloying addition of molybdenum which affected the microstructural evolution during heat treatment, specifically by inhibition of the increase in grain size.
S.W. Du, R.V. Ramanujan, Journal of Magnetism and Magnetic Materials 292 (2005) 286-298

B1820 – Enthalpies of mixing of metallic systems relevant for lead-free soldering: Ag-Pd and Ag-Pd-Sn

The partial and integral enthalpies of mixing of binary liquid Ag-Pd alloys (with compositions up to about 55 at.% Pd) were determined at 1400°C. A Calvet type microcalorimeter was used for the measurements employing a drop calorimetric technique. Additionally, eight sections in the Sn-rich corner of the ternary Ag-Pd-Sn system, which is relevant for lead-free soldering, were investigated at 900°C. The ternary interaction parameters were fitted using the Redlich-Kister-Muggiano model for substitutional solutions. The isoenthalpy curves for Ag-Pd-Sn at 900°C were constructed for the integral molar enthalpy of mixing.
C. Luef, A. Paul, H. Flandorfer, A. Kodentsov, H. Ipser, Journal of Alloys and Compounds 391 (2005) 67-76

B1817 – Crystallization kinetics of Ge20Te80 chalcogenide glasses doped with Sb

A study of kinetics of non-isothermal crystallization process for Ge20-xTe80Sbx (x = 0; 3; 4; 5) system was reported and interpreted in this work by using Matusita's model. From the differential scanning calorimetry (DSC) traces obtained under dynamic conditions, the activation energy of growth process and values of n and m which are numerical factors depending on crystallization mechanisms are evaluated. The validity of Matusita's model was ascertained by comparison with the results obtainedby application of two well-known methods which are Ozawa andKissinger ones.
N. Ziani, M. Belhadji, L. Heireche, Z. Bouchaour, M. Belbachir, Physica B 358 (2005) 132-137

B1812 – Synthesis and thermodynamic properties of a metal-organic framework: [LaCu6(µ-OH)3(Gly)6im6](ClO4)6

A metal-organic complex, which has the potential property of absorbing gases, [LaCu6(µ-OH)3(Gly)6im6](ClO4)6 was synthesized through the self-assembly of La3+, Cu2+, glycine (Gly) and imidazole (Im) in aqueous solution and characterized by IR, element analysis and powder XRD. The molar heat capacity, Cp,m, was measured from T = 80 to 390K with an automated adiabatic calorimeter. The thermodynamic functions [HT -H298.15] and [ST -S298.15] were derived from the heat capacity data with temperature interval of 5K. The thermal stability of the complex was investigated by differential scanning calorimetry (DSC).
X-C. Lv, Z-C. Tan, X-H. Gao, Z-H. Zhang, L-N. Yang, J-N. Zhao, L-X. Sun, T. Zhang, Thermochimica Acta 450 (2006) 102-104

B1803 – A combined characterization of zinc hot-dip galvanized wires with DSC, XRD and SEM

The effect of Pb and Sn on the structure of zinc hot-dip galvanized coatings on steel wires is examined. The coating quality is often low because of the Sandelin effect. An improvement could be expected if 1.0 mass% Pb is added to the Zn bath. In this case the phase formation is enhanced, while the coating thickness is reduced. The Sn addition at the same concentration promotes the formation of the phase but it does not affect the thickness.
N. Pistofidis, G. Vourlias, E. Pavlidou, K. Chrissafis, G. Stergioudis, E.K. Polychroniadis and D. Tsipas, Journal of Thermal Analysis and Calorimetry 86 (2006) 417-422

B1800 – Enthalpies of formation of Ni-Sn compounds

Enthalpies of formation ( fH) of nickel-tin compounds have been measured by direct reaction calorimetry: fHNi3Sn2 LT = -29.0 ± 0.9 kJ mol-1 (approximate value); fHNi3Sn2 HT = -35.0 ± 0.2 kJ mol-1; fHNi3Sn2 HT = -34.3 ± 1.7 kJ mol-1; fHNi3Sn HT = -21.0 ± 2.4 kJ mol-1; fHNi3Sn LT = -24.4 ± 1.2 kJ mol-1 and fHNi3Sn4 = -29.8 ± 1 kJ mol-1. Standard states are solid Ni and liquid Sn at the respective working temperatures: 728, 1288, 1389, 1332, 943 and 846 K. The enthalpy of formation of the Ni3Sn high-temperature form is measured for the first time, while that of Ni3Sn2 LT must be considered as approximate because the corresponding calorimetric reaction was incomplete. The chemical and phase compositions of the specimens have been verified by electron probe microanalyses and by high- and room-temperature X-ray diffraction analyses. Unidentified thermal effects have been observed in the Ni3Sn2 phases region.
G.P. Vassilev, K.I. Lilova, J.C. Gachon, Thermochimica Acta 447 (2006) 106-108

B1797 – Self-propagating high-temperature synthesis of IrAl and its application to coating process

An IrAl intermetallic compound was fabricated by a self-propagating high-temperature synthesis (SHS) process. Single phase IrAl pellets were produced; however, the IrAl coatings produced, with the aid of numerical simulations, contained unreacted Ir and was found to have poor adhesion. Nevertheless, this study confirmed that IrAl coatings can be obtained using the SHS process.
M. Ode, H. Murakami, H. Onodera, Scripta Materialia 52 (2005) 1057-1062

B1790 – Comparison of nano-indentation hardness to microhardness

With a nano-indenter and a microhardness testing machine, nano-indentation hardness and microhardness are measured in a wide load range (0.1-19600 mN) for five materials. Even fused silica and silicon almost have constant hardness during the load range, the nanoindentation hardness of copper, stainless steel and nickel titanium alloy shows obvious indentation size effect, namely that the hardness decreases with the increase of depth. For the measured materials, the nano-indentation hardness is about 10-30% in magnitude larger than the microhardness. The main reasons can be explained as the analysis of the nano-indentation hardness using the projected contact area at peak load Ac instead of the residual projected area Ar, as well as the purely elastic contact assumption describing the elastic/plastic indentation process. The analysis based on a simple model indicates that Ac is always smaller than Ar, and the more heavily the indent piles up (or sinks in), the larger the difference between the nano-indentation hardness and microhardness.
L. Qian, M. Li, Z. Zhou, H. Yang, X. Shi, Surface & Coatings Technology 195 (2005) 264- 271

B1784 – Monotectic four-phase reaction in Al-Bi-Zn alloys

Thermodynamic phase diagram calculations were used for the systematic search for a monotectic four-phase reaction in ternary Al-alloys. Systems with intermetallic phases and also the elements Cd and Hg were excluded in the present search. The ternary Al- Bi-Zn is a rare occasion where such a reaction, L' = L" + (Al)' + (Zn), actually occurs. Experimental work could be focused on key samples in that system and involved DSC for thermal analysis and calorimetry, and also metallographic analysis using SEM/EDX. Experimental results verify the existence of the monotectic reaction and were also used for a quantitative thermodynamic modeling of Al-Bi-Zn. Solidification paths and microstructures of Al-Bi-Zn alloys are shown to be rather complex. Using thermodynamic calculations, these rich details involving up to three invariant reactions and unexpected monovariant reaction types can be clearly revealed and understood.
J. Grobner, D. Mirkovic, R. Schmid-Fetzer, Acta Materialia 53 (2005) 3271-3280

B1776 – The role of phase transition in the fretting behavior of NiTi shape memory alloy

Fretting wear tests of a NiTi shape memory alloy plate against a GCr15 steel ball (NiTi/GCr15) were performed on a horizontal servohydraulic fretting test machine at various temperatures. As a comparison, fretting wear tests of a GCr15 steel plate against a GCr15 steel ball were also conducted under the same experimental conditions. The fretting behavior of GCr15 and NiTi alloy was studied by analyzing both the frictional logs (variation of the tangential force Ft and displacement D with the number of fretting cycles N) and fretting scar features. The experiments showed that NiTi exhibits much better fretting behavior than GCr15 steel even with a relatively low hardness at room temperature.With an increase in temperature from 22 to 200°C, while the fretting behavior of GCr15 is almost temperature independent, the range of the partial slip regime of NiTi/GCr15 becomes small and the fretting wear resistance of NiTi is found to anomalously decrease with an increase in nominal hardness. It was demonstrated that the unique temperature dependent phase transition properties of NiTi play a key role in its fretting behavior. The stress-induced phase transition not only greatly improves the elastic accommodation ability of NiTi through the large recoverable deformation, but also increases its fretting wear resistance through the transformation shielding effect. With the increasing temperature, the elastic accommodation ability of NiTi decreases not only because of the increase of austenite elastic modulus and phase transition stress but also the plastic deformation of austenite, which in turn causes a small range of the partial slip regime in the NiTi/GCr15 pair. As the temperature increases, the decrease in fretting wear resistance is attributed to the decrease in the elastic accommodation ability of NiTi and the plastic yield of austenite before phase transition at high temperatures.
L. Qian, Z. Zhou, Q. Sun, Wear 259 (2005) 309-318

B1772 – Calorimetric measurement of the intermetallic compounds Cr3Ga and CrGa4 and thermodynamic assessment of the (Cr-Ga) system

The enthalpies of formation have been measured for the two binary compounds Cr3Ga and CrGa4 richest and least rich in chromium of the (Cr-Ga) system. We have used two types of calorimetric method: direct reaction and progressive precipitation calorimetry. Thermodynamic optimizations for the binary (Cr-Ga) system using Calphad method are investigated and a set of parameters describing the Gibbs energy of the different phases is given, the phase diagram has been also calculated and presented.
A. Belgacem-Bouzida, Y. Djaballah, M. Notin, Journal of Alloys and Compounds 397 (2005) 155-160

B1768 – Incomplete transformation induced multiple-step transformation in TiNi shape memory alloys

The incomplete transformations of TiNi shape memory alloys were investigated. The results show that the incomplete transformation upon heating can induce multiple-step transformations in a TiNi alloy with or without R-phase transformation, but the incomplete transformation upon cooling can induce multiple-step transformations in a TiNi alloy showing R-phase transformation.
Z.G. Wang, X.T. Zu, Scripta Materialia 53 (2005) 335-339

B1767 – Enthalpies of mixing of the liquid phase in the ternary system Ag-Au-Bi

The enthalpies of mixing of the liquid phase of the Ag-Au-Bi ternary alloys along the sections AgxBi1-x-Au (x = 0.11, 0.10 and 0.24) and AuxBi1-x-Ag (x = 0.11 and 0.27) have been determined at 673 and 773 K.We used a SETARAM devised heat flow calorimeter of Tian-Calvet type. The values obtained are almost compatible with estimations from Scientific Group of Thermodata Europe (SGTE) binary database without adding ternary thermodynamic excess parameters. However, slight discrepancies are observed. The result of this study is useful tools for the Ag-Au-Bi ternary system thermodynamic computer optimization in process by the authors.
E. Zoro, D. Boa, C. Servant, B. Legendre, Journal of Alloys and Compounds 398 (2005) 106-112

B1760 – Experimental study of the Ag-Sn-In phase diagram

Combined metallographic, differential scanning calorimetry, X-ray and scanning electron microscopy studies have been performed using 27 ternary alloys. The microhardness of the (Ag), (Ag3Sn) and (Ag4Sn,Ag3In) phases has been measured. The ternary extension of the phase (AgxInySnz, where x?0.36, y?0.61, z?0.03) has been revealed in some specimens, although the binary compound (AgIn2) melts at 166°C. This finding is attributed to the limited cooling rate. The solubility ranges of the solid solution and the intermetallic phases have been determined. The tin and the indium show approximately equal mutual solubility (around 2 at.%) in the ternary extensions of their Ag-Sn or Ag-In phases. The experimental data have been compared with a calculated isothermal section at 280°C and with a vertical section at 2.5 at.% Ag. The thermal analyses have confirmed, in general, the temperatures of the invariant reactions in the Ag-Sn-In system as calculated by literature data.
G.P. Vassilev, E.S. Dobrev, J-C. Tedenac, Journal of Alloys and Compounds 399 (2005) 118-125

B1754 – Phase equilibria in the Ag-Au-Bi ternary system

The aim of the action of Cost 531 taking into account the 11 elements: Ag, Au, Bi, Cu, In, Pb, Sb, Sn, Zn (solder), Ni and Pd (substrate) is the database assessment of candidates for lead free soldering process. Among those elements, we chose to study three of them forming the ternary Ag-Au-Bi system. We have determined its phase diagram using X-ray powder diffraction, differential scanning calorimetry and electron probe micro-analysis. Four vertical sections (isopleths) were studied at 20 at.% Ag, 50 at.% Bi, 85 at.% Bi and the section with ratio Ag:Au = 1:4. The results give one transitory peritectic reaction and an extremely large primary crystallization area, L + , restricting thus the two others reactions (L + (Bi) and L +Au2Bi). Schematic representations of the ternary equilibria are given.
E. Zoro, E. Dichi, C. Servant, B. Legendre, Journal of Alloys and Compounds 400 (2005) 209-215

B1751 – Microstructure and electrochemical properties of high entropy alloys-a comparison with type-304 stainless steel

High entropy alloys (HEAs) are a newly developed family of multi-component glassy alloys composed of several major alloying elements, such as copper, nickel, aluminum, cobalt, chromium, iron, silicon, titanium, etc. The HEA studied had a nearly amorphous structure as proven by X-ray diffraction (XRD), selected area diffraction (SAD), and differential scanning calorimetry (DSC) analysis. The dendritic phase was composed mainly of a non-crystalline phase with a little body centered cubic (BCC) structure whereas the interdendritic phase had an amorphous structure containing small amounts of nano-scale precipitates. The HEA had a high degree of atomic disorder with mechanical properties comparable to that of glass and it was therefore hard but brittle. Its hardness (Hv860) was much higher than that of type- 304 stainless steel (Hv265). The anodic polarization curves of the HEA, obtained in aqueous solutions of NaCl and H2SO4, clearly indicated that the general corrosion resistance of the HEA at ambient temperature ( 25°C) is superior to that of 304S, irrespective of the concentration of electrolyte in the range 0.1-1 M. On the other hand, the HEA s resistance to pitting corrosion in a Cl environment is inferior to that of 304S, as indicated by a lower pitting potential and a narrower passive region for the HEA. Tests in 1 N sulfuric acid containing different concentrations of chloride ions showed that the HEA has least resistance to general corrosion at a chloride ion concentration of 0.5 M (close to the concentration in seawater). The lack of hysteresis in cyclic polarization tests confirmed that the HEA -like 304S- is not susceptible to pitting corrosion in chloride-free 1 N H2SO4.
Y.Y. Chen, T. Duval, U.D. Hung, J.W. Yeh, H.C. Shih, Corrosion Science 47 (2005) 2257-2279

B1746 – Formation of Zr-based bulk metallic glasses from low purity materials by scandium addition

Zr55Al10Cu30Ni5 bulk metallic glass (BMG) is formed by using low purity sponge zirconium, instead of high purity zirconium, and other high purity raw materials with a small amount of scandium addition. The results show that glass forming ability and thermal stability of the Zr55Al10Cu30Ni5 alloy are improved with scandium addition. Compressive fracture strength is similar to that of BMG alloy produced with high purity raw materials. However, plasticity of BMGs with sponge zirconium and scandium addition deteriorates.
F. Jiang, Z.J. Wang, Z.B. Zhang, J. Sun, Scripta Materialia 53 (2005) 487-491

B1734 – Selection of optimum microstructure for improved corrosion resistance in a Ti-5%Ta-1.8%Nb alloy

This paper presents the results on (i) selection of microstructure with improved corrosion resistance in a Ti-5%Ta- 1.8%Nb alloy and (ii) optimization of thermo-mechanical treatment to achieve the desirable structure. Ti-5%Ta- 1.8%Nb is an a + b alloy and the decomposition of bcc b! a + b is found to proceed via a number of transformation modes leading to different morphological products of a and b. The distribution of isolated b particles in a matrix of equiaxed a offered superior corrosion resistance in comparison to a lamellar a + b structure. In an attempt to obtain this desired structure, the b annealed alloy with a lamellar structure was subjected to a series of thermal and thermomechanical treatments. A combination of thermal and mechanical treatments was found to be essential to achieve the structure of equiaxed a with discrete b particles.
R. Mythili, S. Saroja, M. Vijayalakshmi, V.S. Raghunathan, Journal of Nuclear Materials 345 (2005) 167-183

B1726 – Experimental study of the ternary magnesium-aluminium-strontium system

The phase diagram of the ternary magnesium-aluminium-strontium (Mg-Al-Sr) system has been investigated with 22 different alloys by DSC, XRD and metallography. Liquidus temperature and enthalpy were determined. Al4Sr and (Mg) were found to be the dominating phases in the investigated alloys. Four new phase fields have been identified; the new phases were tentatively designated as t1, t2, t3 and t4 and may be ternary intermetallics or solid solutions. Some peak positions of t1 corresponded well with the newly reported ternary compound Al3Mg13Sr. The identified phases in the as-cast condition were found consistent and thermodynamically stable with the post-DSC sample (25 <--> 700°C) in the investigated alloys. Two ternary eutectic transformations have been observed. The experimental results were compared with the pertinent thermodynamic findings. A considerable discrepancy in the solid-phase transformation temperature was observed. Predicted phases by the thermodynamic calculation do not agree with the present XRD results for nine samples, which suggests that this system should be remodeled
M.A. Parvez, M. Medraj, E. Essadiqi, A. Muntasar, G. Dénès, Journal of Alloys and Compounds 402 (2005) 170-185

B1707 – Modeling of precipitation hardening in pre-aged AlMgSi(Cu) alloys

A new analytical method to estimate the evolution of the relative volume fraction of precipitates during artificial aging of preaged AlMgSi(Cu) alloys in the underaged regime is introduced. The analytical results demonstrate that the precipitation processes in AlMgSi(Cu) alloys are isokinetic in commercially relevant temperature ranges. The theory of transformations is used to model isothermal and non-isothermal aging kinetics in isokinetic systems where the precipitate nuclei pre-exist at the start of aging and definite precipitate contents are reached at the end of transformation. A simple physically based model is also developed for the prediction of the average size of precipitates during artificial aging of pre-aged alloys, when "growth" is the controlling mechanism of precipitation. The microstructural models are combined with a previously developed yield strength model and the evolution of yield strengths during isothermal and non-isothermal aging of AlMgSi(Cu) alloys, with various pre-aging histories, are modeled. The analytical method and the microstructural and yield strength models are validated using experimental results.
S. Esmaeili, D.J. Lloyd, Acta Materialia 53 (2005) 5257-5271

B1689 – Temperature memory effect in CuAlNi single crystalline and CuZnAl polycrystalline shape memory alloys

Temperature memory effect (TME) induced by incomplete cycling in CuAlNi single crystalline and CuZnAl polycrystalline shape memory alloys were investigated by differential scanning calorimeter. Results showed that the TME is a common phenomenon in shape memory alloys, caused by a partial martensite to parent phase transformation.
Z.G. Wang, X.T. Zu, H.J. Yu, X. He, C. Peng and Y. Huo, Thermochimica Acta 448 (2006) 69-72

B1654 – Structure and phase transformation of melt-spun Gd5Si2Ge2

Gd5Si2Ge2 materials were prepared by rapid solidification at different wheel speeds. The crystal phase and phase transformation of the rapidly solidified materials have been investigated by powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The materials contained mainly a Gd5Si2Ge2-type single phase at a wheel speed of 20 m/s; a Gd5Si4-type major phase and a Gd5Si2Ge2-type minor phase at 30 m/s; a Gd5Si4-type single phase at 40 m/s; and Gd5Si4-type and Gd5Si2Ge2-type double phase at 50 m/s. A first-order phase transformation occurred at approximately 273 K in the materials prepared at a wheel speed of 20 m/s whereas a second-order phase transformation appeared at approximately 290 K in the materials prepared at other wheel speeds. Furthermore, we observed some exothermic peaks located at 250-300°C in the DSC curves for all the melt-spun samples. These exothermic reactions can be attributed to the crystallization of a small amount of glassy phase. The presence of glassy phase has been confirmed by both the electron diffraction pattern observed in the TEM observation and the glass transition found in the DSC scan.
H. Fu, X.T. Zu, and T.D. Shen, Thermochimica Acta 445 (2006) 53-56

B1619 – Temperature memory effect in TiNi-based shape memory alloys

An incomplete thermal cycle upon heating of a shape memory alloy (arrested at a temperature between austenite transformation start and finish temperatures, As and Af) induced a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon is named temperature memory effect (TME). In this work, the TME induced by incomplete cycling in TiNi and TiNiCu ribbons, TiNiCu thin films and TiNiCu wire showing two-way shape memory effect was systematically investigated by performing either a single incomplete cycle, or a sequence of incomplete cycles with different arrested temperatures. Results showed that the TME is a common phenomenon in shape memory alloys, caused by a partial martensite to parent phase (M => P) transformation. N points of temperatures could be memorized if N times of incomplete cycles on heating were performed with different arrested temperatures in a decreasing order. On the contrary, if a partial parent phase to martensite (P => M) transformation was performed by an incomplete cycle on cooling, the next complete P => M transformation did show any evidence of TME. The incomplete cycle of parent phase to R-phase and R-phase to parent phase transformations did not show any evidence of TME. Results showed that the capability to memorize the temperature is a specific characteristic of the martensitic phase, and the decrease in microstrains and elastic energy after ICH procedure has significant contributions to the TME.
Z.G. Wang, X.T. Zu, Y.Q. Fu and L.M. Wang, Thermochimica Acta 428 (2005) 199-205

B1575 – Effect of heating / cooling rate on the transformation temperatures in TiNiCu shape memory alloys

In this note, the effects of heating and cooling rate on the transformation characteristics in TiNiCu shape memory alloy were investigated by differential scanning calorimetry (DSC). The results showed that the martensitic end transformation temperature (Mf) and reverse end transformation temperature (Af) depend strongly on the scanning rate of the heating-cooling process, Mf decreased and Af increased with increasing cooling/heating rate. However, the martensitic start transformation temperature (Ms) and reverse start transformation temperature (As) are not so sensitive to the scanning rate. The results are in good agreement with simulation results of our previous published model of martensitic transformation [Y. Huo, X.T. Zu, A. Li, Z.G. Wang, L.M. Wang, Acta Mater. 52 (2004) 2683].
Z.G. Wang, X.T. Zu, Y. Huo, Thermochimica Acta 436 (2005) 153-155

B1565 – Study of incomplete transformations of near equiatomic TiNi shape memory alloys by DSC methods

The incomplete transformations of near equiatomic TiNi shape memory alloys were investigated by differential scanning calorimeter (DSC). The results showed that the incomplete transformation can induce multistage phase transformation in a sample showing R-phase transformation, when the turn back temperature located in a value between Rf and Ms, the heat flow detected upon following heating only shows one endothermic peak. With decreasing the turn back temperature to a temperature between Ms and Mf , two endothermic peaks (multistage phase transformation) can be observed upon the following heating. There were no incomplete transformation induced multistage phase transformations in a sample without R-phase transformation.
Z.G. Wang, X.T. Zu, Y.Q. Fu, Material science and Engineering A 390 (2005) 400-403

B1563 – Thermal property characterization of a titanium modified austenitic stainless steel (alloy D9)

The temperature dependence of lattice parameter and enthalpy increment of alloy D9, a titanium modified nuclear grade austenitic stainless steel were studied using high temperature X-ray diffraction and inverse drop calorimetry tech- niques, respectively. A smooth variation of the lattice parameter of the austenite with temperature was found. The instantaneous and mean linear thermal expansion coefficients at 1350 K were estimated to be 2.12 . 10 5 K 1 and 1.72 . 10 5 K 1, respectively. The measured enthalpy data were made use in estimating heat capacity, entropy and Gibbs energy values. The estimated isobaric heat capacity Cp at 298 K was found to be 406 J kg 1 K 1. An integrated theoretical analysis of the thermal expansion and enthalpy data was performed to obtain approximate values of bulk modulus as a function of temperature.
A. Banerjee, S. Raju, R. Divakar, E. Mohandas, G. Panneerselvam, M.P. Antony, Journal of Nuclear Materials 347 (2005) 20-30

B1562 – Enthalpy measurements on a titanium modified austenitic stainless steel

The enthalpy values for a titanium modified, neutron swell-resistant austenitic stainless steel (D9) with a titanium to carbon ratio of about six, have been measured by drop calorimetry technique in the temperature range 295 to 1100 K. The specific heat of D9 has also been estimated from the measured variation of enthalpy with temperature.
A. Banerjee, S. Raju, R. Divakar, E. Mohandas, Materials Letters 59 (2005) 1219-1222

B1540 – Effect of TixAly catalysts on hydrogen storage properties of LiAlH4 and NaAlH4

The high catalytic activities of TiCl4 and TiCl3 on the hydrogen storage properties of alkali metal aluminum hydrides have been attributed to intermetallic TiAl3. Therefore, in this work, the hydrogen storage properties of LiAlH4 and NaAlH4 doped with titanium aluminum alloys were investigated. The dopants were incorporated into the alanates by ball milling. The catalysts studied included TiAl3, Ti3Al, elemental titanium, and elemental aluminum. Ball milling in the absence of the catalyst was found to decrease the release temperature of hydrogen. Doping LiAlH4 with Ti3Al, TiAl3 and elemental aluminum additionally reduced the temperature required for hydrogen release. That effect was not observed for mixtures with NaAlH4.
M. Resan, M.D. Hampton, J.K. Lomness, D.K. Slattery, International Journal of Hydrogen Energy 30 (2005), 1417-1421

B1539 – The activation of Mg2Ni for initial hydrogen uptake by treatment with water vapor

The alloy Mg1Ni is a good candidate for the storage of hydrogen[ One problem associated with the use of this alloy for hydrogen storage is the di.culty of its activation for initial hydrogen uptake[ A great deal of research has been done in this area[ However the resulting methods require hazardous conditions and reagents and:or prohibitively long periods of time[ It has been found in this laboratory that water vapor can be used to activate Mg1Ni for hydrogen uptake in as little as 0 h at ambient temperature and pressure[ This _nding is particularly interesting considering the long!held view of water acting as a poison in metallic hydrogen storage systems[ 0888 International Association for Hydrogen Energy[
M.D. Hampton, R. Juturu, J.Lomness, International Journal of Hydrogen Energy 24 (1999) 981-988

B1522 – Etude du système ternaire Ag-Au-Bi : le diagramme d’équilibre entre phases

E. Zoro, E. Dichi, C. Servant, B. Legendre, 30ieme JEEP (2005) 31-33

B1483 – Enthalpies of mixing of liquid alloys in the In-Pd-Sn system and the limiting binary systems

The partial and integral enthalpies of mixing of molten binary In-Pd (up to about 29 at.% Pd), In-Sn (entire compositional range) and Pd-Sn (up to about 53 at.% Pd) alloys were determined at 900°C. A Calvet-type microcalorimeter was used for the measurements employing a drop calorimetric technique. Additionally, five sections in the ternary In-Pd-Sn system (compositions up to about 40 at.% Pd) were investigated at 900°C. The ternary interaction parameters were fitted using the Redlich-Kister-Muggiano model for substitutional solutions. The isoenthalpy curves for In-Pd-Sn at 900°C were constructed for the integral molar enthalpy of mixing. Furthermore, the experimental results in the ternary system were compared with calculated values obtained by employing different binary extrapolation models.
C. Luef, H. Flandorfer, H. Ipser, Thermochimica Acta 417 (2004) 47-57

B1464 – Crystallization kinetics of amorphous Fe(75-x)AgxSi9B16

The influence of Ag admixtures on the crystallization process of amorphous Fe-Si-B alloys of the series Fe75-xAgxSi9B16 (x=0, 1, 2, 3 and 4) was studied by differential scanning calorimetry (DSC) measurements at different heating rates. Two exothermic peaks were observed in the DSC trace when the Ag content was 2-4 at.% and one when it was 1 at.%, respectively. The activation energy was calculated both with Kissinger's and isoconversional Flynn, Wall and Ozawa methods. The possibility of analysis with the JMA model using the Avrami plot was investigated for the third stage of crystallization.
K. Chrissafis, Thermochimica Acta 411 (2004) 7-11

B1460 – Crystallization kinetics of amorphous Fe(78-x)MoxSi9B13

In this work we study the influence of Mo admixtures on the crystallization process of amorphous Fe78-xMoxSi9B13 (x=1, 2, 3 and 4) alloys by measurements of differential scanning calorimetry and on the soft ferromagnetic properties of the alloys by magnetic measurements. The addition of Mo by replacing Fe, results in magnetic hardening of materials. In DSC curves two peaks appear which are distinct when the concentration of Mo is 1 at.% and partly overlap when the Mo content is 2 at.%. Further increase in the Mo content leads to the appearance of just one peak. The activation energy was calculated both with Kissinger's and isoconversional Flynn, Wall and Ozawa methods.
K. Chrissafis, K. G. Efthimiadis, E. K. Polychroniadis, S. C. Chadjivasiliou, Journal of Thermal analysis and calorimetry 74 (2003) 761-767

B1446 – Crystallization kinetics of amorphous Fe(75-x)CuxSi9B16

In this work the influence of Cu admixtures on the crystallization process of amorphous Fe-Si-B alloys is studied, based on measurements of differential thermal calorimetry of the series Fe75-xCuxSi9B16 (x=0, 1, 2, 2.8 and 3.5) during their heating with different heating rates. The first crystallization stage can not be traced for any of the amounts of Cu content examined, while the second stage is observed only when the Cu content is 1 at%. The activation energy as estimated with Kissinger's method for the third crystallization stage has a mean value of 326 kJ mol-1 and with the isoconversional Flynn, Wall and Ozawa method is almost constant when 0.05<<0.6 and exhibits a small monotical decrease when >0.6. The main crystallization peak can not be described by means of a single JMA-type function.
K. Chrissafis, Journal of Thermal Analysis and Calorimetry 73 (2003) 745-753

B1421 – Modeling of precipitation hardening for the naturally aged Al-Mg-Si-Cu alloy AA6111

The effect of natural aging on the artificial aging behavior of the Al-Mg-Si-Cu alloy AA6111 is examined by isothermal calorimetry and the results are analyzed in a new kinetic model. The model describes the kinetics of concurrent precipitate formation and cluster dissolution during artificial aging of the alloy with variable levels of natural aging. The kinetic model is then combined with a recently developed yield strength model for AA6111 to predict the precipitation hardening behavior of the naturally aged alloy. The validity of both models is verified by agreement between the predictions of the models and independent experimental results.
S. Esmaeili, D.J. Lloyd and W.J. Poole, Acta Materialia 51 (2003) 3467-3481

B1420 – On the precipitation-hardening behavior of the Al-Mg-Si-Cu Alloy AA6111

The precipitation-hardening behavior of aluminum alloy AA6111 during artificial aging and the influence of prior natural aging on the aging behavior were investigated. The evolution of microstructure was studied using quantitative transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The evolution of the relative volume fraction of precipitates for the solutiontreated alloy was determined using isothermal calorimetry and a new analysis based on the DSC technique. Quantitative TEM was also used to obtain the rate of precipitation of microscopically resolvable phases during aging at 180°C. Three types of precipitates, i.e., unresolved Guinier-Preston (GP) zones, b0, and Q9, were found to form during aging at 180°C. The evolution of yield strength was related to the evolution of microstructure. It was found that the high hardening rate during artificial aging for the solution-treated alloy is due to the rapid precipitation of the b0 phase. Natural aging prior to artificial aging was found to decrease the rate of precipitation of b0. The slow hardening rate for the naturally aged alloy was attributed to the slower nucleation and growth of b0 phase.
S. Esmaeili, X. Wang, D.J. Lloyd and W.J. Poole, Metalurgical and Materials Transactions 34A (2003) 751-763

B1418 – Kinetic analysis of the alpha-beta HgI2 phase transition : using isothermal and non-isothermal DSC

The kinetics of the - phase transition of HgI2 were investigated by isothermal and non-isothermal differential scanning calorimetry. The effective activation energy of the transition, 415±40 kJ mol-1, was determined applying the methods of Kissinger and Ozawa. The transition kinetics were described by the Johnson-Mehl-Avrami model and the value of the Avrami exponent n was found to range from high values (n>3) at the early stages to lower values at later stages of the transformation, with an average value of 2.
M. Daviti, K. Chrissafis, K.M. Paraskevopoulos, E.K. Polychroniadis and T. Spassov, Journal of Thermal Analysis and Calorimetry 70 (2002) 605-614

B1403 – The Ag-Bi-In system : enthalpy of formation

The Ag-Bi-In ternary alloys as lead-free solder candidates in electronic industry were studied. Using a high temperature microcalorimeter, the enthalpy of formation of this system was determined along six isoplethic sections (xBi/xIn=1/4, 1/2, 1/1, 62/38, xAg/xBi=1/3 and xAg/xIn=1/1) in the temperature range of 809-911 K. A critical analysis of these results leads us to the following conclusion: the enthalpy of formation of the Ag-Bi-In liquid system (?mixHm(Ag-Bi-In)°=f(xAg,xBi)) can be correctly represented by the Toop relation on the entire ternary molar fraction range.
A. Sabbar, A. Zrineh, J.P. Dubès, M. Gambino, J.P. Bros, G. Borzone, Thermochimica Acta 395 (2003) 47-58

B1395 – The equilibrium phase diagram of the copper-indium system : a new investigation

The entire phase diagram of the Cu-In system was investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), metallography and electron probe microanalysis (EPMA) studies. The results indicate the existence of a solubility region of In in Cu with the limit of the solid solution at 5.20 at.% In at 400°Cand of six intermediate phases, the three low-temperature phases delta, eta and Cu11In9, and the three high-temperature phases gamma, eta' and beta. The boundaries of each phase were defined with respect to temperature and composition.
Z. Bahari, E. Dichi, B. Legendre, J. Dugué, Thermochimica Acta 401 (2003) 131-138

B1382 – Suivi des transformations de phase dans un alliage Al-Mn-Fe-Si lors du chauffage avant homogénéisation par méthodes in situ

M. Dehmas, P. Archambault, M. Serriere, E.A. Gautier, Matériaux (2002)

B1365 – Kinetic study of the oxidation by water vapour of a zirconium based alloy: recrystallised Zircaloy-4

F. Ledoux, F. Valdivieso, M. Pijolat, M. Soustelle, A. Frichet, P. Barberis, Materials Science Forum, vols 369-372 (2001) 223-230

B1359 – Phase equilibria, calorimetric study and thermodynamic modeling of Mg-Li-Ca alloys

The binary Ca-Li and the ternary Ca-Li-Mg systems were studied experimentally by calorimetry and phase equilibration and also by thermodynamic calculations using the Calphad method. The enthalpy of formation of the binary phase CaLi2 was investigated by drop solution calorimetry in a liquid aluminum bath. Ternary phase equilibria at 150°C were studied with 54 different alloys annealed for 400 h and analyzed by X-ray diffractometry. A thermodynamic assessment of the binary Ca-Li system was performed. All available experimental data agree with the calculation in the binary Ca-Li system. In the ternary Ca-Li-Mg system, a complete ternary solubility of CaMg2 and CaLi2 at 150°C was found. For this Ca(Li,Mg)2 solution phase, a thermodynamic interaction parameter was assessed. Based on the present thermodynamic datasets and those of the binaries Ca-Mg and Li-Mg from literature, the phase equilibria in the entire ternary system were calculated. Isothermal and vertical sections of the phase diagram and the projection of the liquidus surface are shown. These calculated phase diagrams are well supported by the experimental data.
J. Gröbner, R. Schmid-Fetzer, A. Pisch, C. Colinet, V.V. Pavlyuk, G.S. Dmytriv, D.G. Kevorkov, O.I. Bodak, Thermochimica Acta 389 (2002) 85-94

B1338 – Crystallization of steelslag

The heat flux and crystallization sequence during solidification of a steelslag melt have been studied. The experiments serve to determine the controlling parameters for slag freezing onto the inner-wall of a converter vessel used in steel production. Such a slag layer can provide a protective layer that diminishes the wear of the refractory wall of the vessel.
Chris Kooij, Setaram news n°6 (2001)

B1337 – Oxidation of MoSi2 and alumina platelets MoSi2 composites

MoSi2 is an intermetallic material with a high melting temperature (2030°C) and an excellent oxidation resistance. It is used as a heating element for high temperature furnaces and can operate above 1700°C in air. But MoSi2 shows low toughness and high creep rate at elevated temperature. MoSi2 can be reinforced by adding alumina platelets in order to increase the creep resistance and the lifetime of the heating elements
G. Fantozzi, S. Cardinal, Setaram news n°6 (2001)

B1336 – Phase diagram investigation in high-melting rare earth-transition metal compound forming systems

To grow single crystals of different classes of high melting multi-component Rare Earth(RE)-Transition Metal(TM)-compounds by vertical floating zone melting details of the phase diagrams are necessary. Therefore, phase diagram features of RE-Ni-B-C and RE-Pd-Si multi-component systems relevant for the crystallization process of RENi2B2C and RE2PdSi3 phases of interest have been revealed.
G. Behr, Setaram news n°6 (2001)

B1331 – Melting and solidification studies by advanced thermal analysis of cast iron

A tool widely employed in foundry is measuring the melt temperature during free cooling in cups. Thermal analysis curves provide information on liquidus, eutectic, solidus temperatures and recalescence effects. More advanced analyses can be performed in the laboratory using differential devices where a temperature program is imposed to both the sample and an inert reference. The sensitivity in the detection of temperature points is enhanced and quantitative determination of the heat release during solidification, and therefore of the solid fraction, becomes feasible. In this work we have employed a high temperature differential scanning calorimeter (Setaram HTDSC) capable of reaching temperatures up to 1600°C to follow melting and solidification of master alloys for the production of lamellar, compact graphite and spheroidal cast irons, at various heating and cooling rates under protective helium atmosphere. Binary Fe-C alloys prepared in the laboratory with composition of 4.3 wt% C were analysed as well. The solid fraction as a function of temperature is obtained by integration of the DSC traces. The correlation between thermal data obtained by HTDSC, free cooling in cups and microstructure is shown.
L. Battezzati, M. Baricco, F. Marongiu, G. Serramoglia, D. Bergesio, Metallurgical Science and Technology pp 16-20

B1310 – Enthalpies of formation of Cd0.83Ni0.17 and Cd0.5Ni0.5

R. Agarwal, R. Prasad, V. Venugopal, Thermans (2000) 91-92

B1309 – Enthalpy increments of Cd0.83Ni0.17 and Cd0.5Ni0.5

R. Agarwal, R. Prasad, V. Venugopal, Thermans (2000) 89-90

B1263 – Heat capacity measurements by differential scanning calorimetry in the Pd-Pb, Pd-Sn and Pd-In systems

Molar heat capacities at constant pressure of six solid solutions and 11 intermediate phases in the Pd-Pb, Pd-Sn and Pd-In systems were determined each 10 K by differential scanning calorimetry from 310 to 1000 K. The experimental values have been fitted by polynomials Cp=a+bT+cT2+d/T2. Results are given, discussed and compared with available literature data.
L. Perring, J.J. Kuntz, F. Bussy and J.C. Gachon, Thermochimica Acta 366 (2001) 31-36

B1258 – Effects of particle size on the progressive oxidation of nanometer platinum by dioxygen

Platinum particles in nanometer size were dispersed on the y-Al2O3support by the impregnation technique. Oxidation phenomena of the supported particles with dioxygen were pursued by a simultaneous TG-DSC technique. Observed extent of oxidation varies in four consecutive steps, i.e., adsorption of oxygen on the surface of supported platinum crystallites at ambient or lower temperatures, reconstruction of platinum surface for extended accommodation of oxygen above 300 K, formation of a stable surface layer of platinum oxides about 750 K, and desorption of oxygen and/or platinum dioxide over 800 K, while raising the temperature. Measured heat of oxidation (-Qox) generally decreases with the extent of oxidation. The particle size (d) of dispersed platinum has a profound effect on the oxidation. The species of surface platinum oxide formed at 770 K was PtsO2[-?Hf=190 kJ (mol O2)-1] asd< 1.3 nm but became PtsO [-?Hf= 169 kJ (mol O2)-1] ond> 2.0 nm. The heat of dioxygen adsorption (?Had) atT< 300 K could be also correlated with the average diameter (d) of supported platinum according to -?Had[kJ (mol O2)-1] = 406 - 81d/nm when the platinum diameter was less than 2.5 nm.
C-B. Wang and C-T. Yeh, Journal of Catalysis 178 (1998) 450-456

B1253 – Contribution à l’étude du diagramme d’équilibre des phases du système ternaire indium-étain-zinc

The phase diagram of the In-Sn-Zn system has been determined by differential scanning calorimetry on the entire molar fraction range. The location of the liquidus surface and of the ternary eutectic plan have been precised. This new information, in good agreement with some results already published, allows the In-Sn-Zn phase diagram to be proposed.
A. Sabbar, A. Zrineh, M. Gambino and J. P. Bros, Thermochimica Acta 369 (2001) 125-136

B1232 – Thermal properties of beryllium.

The temperatures of transformation Ttr and melting Tm and the enthalpies of transformation ?trH and melting ?mH were measured by difference thermal analysis and by anisothermal calorimetry. The results for the hcp-bcc transformation of Be are Ttr = (1269 ± 1)°C and ?trH = (6100 ± 500) J/mol and those for the melting process are Tm = (1283 ± 2)°C and ?mH = (7200 ± 500) J/mol.
H. Kleykamp, Thermochimica Acta 345 (2000) 179-184

B1228 – Enthalpy of formation of the alpha-phase AIMnSI.

In order to optimise the phase equilibria of higher order alloys containing aluminium, manganese, silicon and iron, it is necessary to use thermodynamic data. In this paper, the heat of dissolution at infinite dilution of manganese in aluminium is determined, and the enthalpy of formation at 298 K of a ternary alloy alpha-AlMnSi is calculated from calorimetric measurements. These values have been measured with a Tian-Calvet calorimeter (Setaram), by dissolution in an aluminium bath at 1073 K.
B. Legendre, Y. Li, P. Kolby, Thermochimica Acta 354 (2000) 1-6

B1227 – A calorimetric study of alloy formation in Au-Cu and Au-In systems.

A calorimetric study of alloy formation in Au-Cu and Au-In systems was carried out. The heats of mixing, H mix, were measured at 1380,1484 and 1604 K for Au-Cu and at 1387, 1449 and 1505 K for Au-In in the full concentration range. The results of experiments were described by approximating equations. Observed values of H mix were discussed using the phase diagrams of the systems. It was shown that the systems become closer to the ideal state with increasing temperature. From the experimental data, the dependencies of the enthalpies of the systems on the composition and temperature were estimated. The simultaneous effects of composition and temperature on enthalpy are represented in 3D diagrams. The specific heats of the alloys, in the temperature range of experiments, were derived from the slopes of enthalpy planes.
A. Bykov and E. Pastukhov, Journal of Thermal Analysis and Calorimetry 60 (2000) 845-850

B1197 – The Fe-Ni distribution between pentlandite and monosulfide solid solution equalized at low temperature.

Two mixtures of pentlandite and the monosulfide solid solution (mss) have been synthesized. The bulk compositions of the samples are Fe6Ni3S8 and Fe3Ni6S8. Differential scanning calorimetry detected exothermic process in the samples under heating. The process takes place in temperature range between phase transition in the mss (near 400 K) and 690 K and is governed by diffusion. X-ray powder diffraction has showed that equilibrium Fe-Ni distribution between pentlandite and the mss is achieved after short-time heating up to 670 K.
V.A. Drebushchak and T.A. Kravchenko, Journal of Thermal Analysis and Calorimetry 56 (1999) 925-929

B1177 – Etude du système ternaire Se-Te-Sn.

This work is a part of the systematic study of the ternary based chalcogenides systems. The aim is to determine the phase equilibrium, and to determine the limits of the phase area. This is done in view to perfecting knowledge of elaboration conditions for new materials and to study of their physical properties. Few works have been devoted to the study of the ternary system Se-Te-Sn, only the cross section SnSe-SnTe has been studied [1] and [2]. The experimental study by DTA, DSC and X-ray diffraction on powder performed at room temperature, exhibits a miscibility gap in the liquid state which narrows as it goes through the Sn-Se binary system. Three cross sections behave as quasi-binary system and six ternary invariants have been exhibited: three ternary eutectics and three ternary quasi-peritectics.
M. Majid, B. Legendre, Journal of Thermal Analysis 54 (1998) 963-990

B1165 – Détermination de quelques données thermodynamiques pour le système Al-Nb-Ti.

En raison d'un manque de données thermodynamiques concernant les alliages du système Al-Nb-Ti, nous avons entrepris la détermination des températures de liquidus et de solidus de quelques alliages ternaires ainsi que des enthalpies de fusion et de formation de quelques phases ternaires, respectivement par analyse thermique différentielle et calorimétrie de chute. Ces résultats ont contribué à optimiser certains paramètres thermodynamiques de la base de données du système ternaire considéré.
F.A. Sadi, C. Servant, J. Gachon, La Revue de Métallurgie-CIT (1998) 1059-1065

B1164 – La calorimétrie à haute température. Principales applications et évolutions récentes.

Les variables thermodynamiques déterminées par calorimétrie ainsi que les méthodes classiquement utilisées pour les obtenir sont présentées sous forme synthétique. L'analyse thermique dans la détermination des diagrammes de phases en fait partie. Des méthodes moins courantes sont mentionnées dans la bibliographie. La calorimétrie est de même replacée parmi les autres méthodes nécessaires à la description complète d'un système thermodynamique : les caractérisations structurales, les mesures d'activités, les calculs et simulations ab initio et enfin les optimisations.
J. Rogez, La Revue de Métallurgie-CIT (1998) 1047-1057

B1139 – Determination of the heat capacity, enthalpy and entropy of crystallisation of ternary eutectic melt in the system 3CaO.2SiO2(C3S2)-CaO.SiO2(CS)-2CaO.Al2O3.SiO2(C2AS)

Inverse drop calorimetry performed in a SETARAM HTC 1800 K was used to measure the values of relative enthalpy of the ternary eutectic melt in the system C3S2-CS-C2AS in the temperature interval 1653-1773 K with regard to the reference state of a mechanical mixture of ")'-C2S, CS, and C2AS crystals of corresponding composition at 298 K. The linear temperature dependence of specific relative enthalpy and the temperature-independent value of specific heat capacity of the eutectic melt (eut.melt) cp(eut.melt)/(Jg -1 K -1) = 1.760 4- 0.089 were determined from measured data. The specific enthalpy of crystallisation of eutectic melt at 1583 K Ac~ysth(eut.melt; 1583 K) = (-324.6 ± 14.4)J g-~ was calculated using specific relative enthalpy of eutectic melt at 1583 K determined experimentally, enthalpies of formation of C3S2, "y-CzS and CS at 298 K, and enthalpy increases on heating of C3S2, CS, and C2AS from 298 to 1583 K taken from literature. The material balance of the process was also used. The value of specific enthalpy of crystallisation of eutectic melt at 1583 K represents about 25% of the heat released on subsequent cooling of the separated crystals of C3S2, CS, and CzAS from 1583 to 298 K.
L. Kosa, I. Nerad, K. Adamkovicova, I. Proks, Thermochimica Acta 302 (1997) 189-193

B1130 – Heat capacity and heat content measurements on binary compounds in the Ru-Si, Ru-Ge, and Ru-Sn systems

Molar heat capacities of Ru0.5Si0.5, Ru0.4Si0.6, Ru0.5Ge0.5, Ru0.4Ge0.6, Ru0.4Sn0.6, and Ru0.3Sn0.7were determined every 10 K by differential scanning calorimetry in the temperature range from 310 to 1080 K. The present results have been fitted by a polynomial function of temperature:Cp=a+bT-cT-2. Heat contents of the six phases have been verified by drop calorimetry. Standard enthalpies of formation are given for the studied compounds.
J.J. Kuntz, L. Perring, P. Feschotte and J.C. Gachon, Journal of Solid State Chemistry 133 (1997) 439-444

B1122 – Enthalpies of formation of Ru-Ge compounds and of the Ge-rich RuGe liquid by direct reaction calorimetry.

The enthalpies of formation of RuGe and Ru2Ge3 have been measured by direct reaction calorimetry at 1173 K. Ru0.4Ge0.6: ?fH (1173 K)=-34.8 kJ mol-1 (±1) Ru0.5Ge0.5: ?fH (1173 K)=-28.7 kJ mol-1 (±1.3) with reference to pure metals in their equilibrium states at the reaction temperature. The Ge rich RuGe liquid was also studied by dissolution of Ru in the liquid alloy of variable composition at 1423 K. The results are compared with the existing literature
L. Perring and J.C. Gachon, Journal of Alloys and Compounds 224 (1995) 228-231

B1120 – The determination of the enthalpy of formation and the enthalpy increment of Cd0.5Te0.5 by Calvet calorimetry.

The enthalpy of formation of Cd0.5Te0.5 has been determined using a Calvet calorimeter at 785 K by direct reaction calorimetry. The heat changes were measured for the additions of Cd(s) or Te(s) from 298 K to a reaction crucible containing the other liquid metal at 785 K. Measurements were also carried out to determine the enthalpy changes due to the direct reaction of the Te(l) and Cd(l) at 785 K. The enthalpies of formation of Cd0.5Te0.5 calculated from the two sets of experiments were in agreement. The HT°---H298° values of the Cd0.5Te0.5 compound have also been determined in the temperature range 406-826 K by the drop method. Using ?Hfm° at 785 K and HT---H298° values of Cd0.5Te0.5, ?Hfm° at 298 K was determined to be -(50.349±0.510) kJ mol-1
R. Agarwal, V. Venugopal and D. D. Sood, Journal of Alloys and Compounds 200 (1993) 93-98

B1049 – Isobaric and isothermal DSC measurements of metal-hydrogen systems

The reversible formation reaction of hydrides from metals and hydrogen is used as a prototype of a gas-solid heterogeneous reaction in order to show that a sufficient thermodynamic and kinetic characterization of such reactions can be achieved by isothermal and isobaric DSC measurements. The isobaric measurements essentially provide thermodynamic data such as reaction enthalpy, yield and the pressure-temperature relation. On the other hand, the isothermal measurements can be used for kinetic evaluation due to the small number of parameters. Results are given for the Pd---H and La---Mg---H systems.
K. Bohmammel, B. Christ, G. Wolf, Thermochimica Acta 271 (1996) 67-73

B1047 – On the phase diagram of Nickel – Tin

R. Haddad, M. Gambino, M. Gaune-Escard, F.P. Bros, A. Ranninger-Havlicek, E. Hayer, JEEP (1996) 168-172

B1046 – Contribution à l’étude thermodynamique des systèmes binaires (terre rare + aluminium) : capacités calorifiques molaires dans la région riche en terre rare

M. Gambino, J.P. Bros, G. Borzone, N. Parodi, R. Ferro, JEEP (1996) 164-166

B1045 – Miscibility curve modelling in the bismuth-zinc system.

F. Adjadj-Bouharkat, J.J. Counioux, J.R. Vignalou, J. Said, JEEP (1996) 120-123

B0994 – Détermination expérimentale du système ternaire antimoine-bismuth-zinc : alliages précurseurs de céramiques semi-conductrices

F. Adjadj, N. Achard, J.R. Vignalou, J. Said, JEEP (1995) 88-91

B0993 – Le système binaire thallium-tellure : mise en évidence du composé défini Tl2Te, calcul du diagramme d’équilibres entre phases

M.C. Record, Y. Feutelais, B. Legendre, JEEP (1995) 102-105

B0992 – Le système (Ga + Pb) : thermodynamique et diagramme des phases

M. Mathon, J.M. Miane, M. Gambino, J.P. Bros, JEEP (1995) 268-271

B0979 – Enthalpy of mixing of liquid Au-Sn alloys

E. Hayer, K.L. Komarek, J.P. Bros, M. Gaune-Escard, Z. Metallkde 72 (1981) 109-115

B0914 – Enthalpy and heat capacity of titanium based alloys

Light metal alloys, as aluminium- and titanium based alloys, are of great interest to aerospace industry but thermodynamic information, mainly heat capacity, is often missing. Then we measured on heating the heat content of seven industrial titanium alloys from room temperature to 600°C with the help of a high-temperature Calvet calorimeter (drop method). Their heat capacities were deduced by derivation of the enthalpy with respect to temperature. The departures from Kopp-Neuman law were calculated.
H. Bros, M-L. Michel, R. Castanet, Journal of Thermal Analysis 41 (1994) 7-24

B0898 – Le système Sn-Se

M. Majid, B. Legendre, J.R. Didry, Y. Feutelais, S.G. Fries, JEEP (1994) 221-223

B0897 – Capacités calorifiques et diagrammes d’équilibre des phases du système Lutécium-Plomb.

N. Parodi, G. Borzone, R. Ferro, M. Gambino, J.P. Bros, JEEP (1994) 81-84

B0850 – The enthalpy of formation of the Cd-Ga-Zn liquid system

Using a high-temperature Calvet calorimeter, the molar enthalpies of formation (?mixHm = f(xCd, xZn)) of the liquid Cd + Ga + Zn alloys were measured at 730 K over a large molar fraction range. The direct drop method (successive additions of solid cadmium
S. Hassam, M. Gambino and J.P. Bros, Thermochimica Acta 217 (1993) 19-28

B0848 – Etude d’alliages précurseurs de céramiques semi-conductrices. Détermination expérimentale des coupes isopléthiques du ternaire zinc-antimoine-bismuth

F. Adjadj, A. Marchand, J.R. Vignalou, J. Said, JEEP (1993) 279-282

B0823 – Is the DSC technique capable of determining accurate specific heats of metallic ribbons ?

Using the scanning (differential) method and a PE DSC in continuous heating regime as well as the integral (enthalpic) method and a SETARAM DSC in a discontinuous heating regime the specific heats of several metallic glassy ribbons were measured. The linear CpM(T) dependencies in the as-quenched, relaxed and also the stable crystalline forms of the ribbons in the medium temperature region were found. The room temperature specific heats of these ribbons, the excess contributions due to the relaxed glassy state as well as the non-relaxed glassy state were determined. The sensitivity of CpM(T) measurements of metallic ribbons was better than 0.2%, the long term reproducibility in the case of glassy ribbons was 2%. They are related to the errors in CpM(T) measurements of synthetic sapphire standard or bulk chaleogenide glasses.
E. Illekova, B. Aba and F.A. Kuhnast, Journal of Thermal Analysis 38 (1992) 397-407

B0811 – Thermodynamic behaviour of Bi-Te alloys

Mesure de l'enthalpie de formation du composé par calorimétrie, dans tout le domaine de composition. Déduction des données thermodynamiques concernant la phase liquide et les composés Bi[2]Te, BiTe et Bi[2]Te[3]. L'enthalpie de formation du mélange est négative pour toutes les compositions et varie linéairement avec la température. L'évolution de la capacité calorifique est typique d'un ordre à courte distance
G. Morgant, Y. Feutelais, B. Legendre, R. Castanet, A. Coulet, Zeitschrift für Metallkunde 81 (1990) 44-48

B0797 – Heats of mixing in ternary systems I:Enthalpies of mixing of indium-antimony tellurium.

The enthalpy of mixing of the ternary system In-Sb-Te was determined using a heat flow calorimeter at 918 K. The experimental data are presented in a graph of isoenthalpic curves and are compared with calculated ternary enthalpies of mixing. A ternary influence is proposed.
B. Gather, B. Legendre and R. Blachnik, Journal of the Less Common Metals 77 (1981) 71-80

B0796 – The ternary system silver-antimony-tellurium. Study of the subternary Sb2Te3 – Ag2Te-Te

The Sb2Te3-Ag2Te-Te subternary system was investigated using thermal analysis, differential scanning calorimetry metallographic technics and X-ray powder analysis. Three isopleth sections were constructed. The transitory reactions were characterized and the eutectic point coordinates were determined. Analysis of polythermal projection of this system is given.
R.M. Marin-Ayral, B. Legendre, G. Brun, B. Liautard and J. C. Tedenac, Thermochimica Acta 131 (1988) 37-45

B0795 – Determination of the formation enthalpy of crystalline and quasicrystalline phases of the Al-Cu-Fe system by solution calorimetry

Dans le cadre de l'étude de la stabilité thermodynamique de la phase icosaédrique dans le système Al-Cu-Fe, nous avons mesuré par calorimétrie de dissolution dans un bain d'aluminium à la température de 976 K l'enthalpie de formation de plusieurs phases binaires et ternaires de ce système. Les mesures ont été effectuées à l'aide d'un microcalorimètre Calvet haute température (SETARAM). L'étalonnage a été réalisé à l'aide d'alumine alpha du NBS. Les variations d'enthalpie de l'aluminium, du cuivre et du fer ont été mesurées entre 298 et 976 K
N. Saâdi, M. Harmelin, B. Legendre, Journal de Chimie Physique 90 (1993) 355-366

B0794 – Enthalpies de mélange du système antimoine-tellure à 909,30K, 911,85 K et 917,95 K.

Thermodynamical data on Sb--Te system at 909,30 K, 911,85 K and 917,95 K. The integral molar enthalpies of formation of liquid Sb-Te alloys were measured at three temperatures, by drop calorimetry. Partial molar enthalpies of formation of these alloys, referring to the pure liquid constituants, and enthalpie of formation at 298 K of the compound Sb.405Te.595 were deduced.
Y. Feutelais, B. Legendre et G. Morgant, Journal of Thermal Analysis 34 (1988) 1093-1100

B0788 – Contribution à l’étude thermodynamique du système Etain-Nickel

R. Haddad, M. Gaune-Escard, E. Hayer, J.P. Bros, JEEP (1992)

B0787 – Etude thermodynamique des alliages liquides Au-Pb et Pd-Pb

R. Castanet, JEEP (1992)

B0769 – Mise au point d’un ensemble de calorimétrie à chute sous atmosphère contrôlée à pression constante

J. Carré, P. Claudy, J.M. Létoffé, JCAT (1992) 415-421

B0752 – Ni + Pd + Ga and Ni + Pd + In liquid alloys : enthalpies of formation

In order to fill the evident gap in the thermodynamic data of nickel-palladium-gallium and nickel-palladium-indium ternary alloys, the enthalpies of formation of these systems in the liquid state have been determined. This was achieved by means of a very high temperature calorimeter (T < 1800 K), using the direct drop method, and based on analogous measurements of the respective binary alloys previously published. Complete automation of the calorimeter led to a good precision even at the highest temperatures. The enthalpies of formation of the ternary liquid alloys were measured between 1400 and 1600 K on the whole composition range. As in the limiting binary systems, enthalpies of formation are negative and non temperature dependent at any composition.
D. EI Allam, E. Hayer, M. Gaune-Escard and J. P. Bros, Journal of Thermal Analysis 37 (1991) 1687-1695

B0750 – Bestimmung der Schmelzwärme von Zinn und von Indium mit einem Dynamischen Wärmestrom-Differenzkalorimeter

W. Hemminger, K. Raetz, PTB-Mitteilungen 99 (1989) 83-88

B0736 – Mesure des capacités calorifiques et des enthalpies de la solution solide AIN-SiC.

The AIN-SiC solid solution was prepared by a reaction of powdered silicon, carbon and aluminium nitride at 2000°C. In the molar ratio range from 1 AIN - 0 SiC to about 0.5 AIN - 0.5 SiC high purity phases with wurtzite structure were obtained. Heat capacities of some mixtures were measured at constant pressure between 313 and 533 K, and also the enthalpy changes between 298 and 453 K. It was observed that addition of small amounts of silicon carbide to aluminium nitride resulted Cp and AH values close to those of silicon carbide.
L. Avignon-PoquiIlon, P. Verdier, Y. Laurent, P. Rebouillon, M. Gambino, H. Bros et R. Castanet, Journal of Thermal Analysis 36 (1990) 2623-2633

B0730 – Contribution à l’étude thermodynamique de l’alliage Or-Plomb par la détermination de ses capacités calorifiques molaires

S. Hassam, M. Gambino, J.P. Bros, JCAT (1991) 337-344

B0698 – Measurement of enthalpic parameters using a differential calorimetric method : application to In-Bi alloys

An attempt is made to develop a calorimetric method by taking full advantage of the differential possibilities offered by the Tian-Calvet calorimeter. This method is intended to measure the enthalpic parameter, defined as the limiting value (dilute solutions) of the derivative of the partial enthalpy of mixing with respect to the concentration, in liquid In-Bi alloys. The results, although rather scattered, exhibit a systematic discrepancy when compared with those obtained by the classical direct reaction calorimetry method with the same calorimeter. They are in better agreement with the values estimated from simple thermodynamic models.
C. Bichara, C. Bergman and J.C. Mathieu, Journal of Thermal Analysis 35 (1989) 2447-2460

B0697 – Etude de la transition de phase du composé Sb0,405 Te0,595 entre 630 K et 665 K

The present study was performed in an attempt to confirm the existence of the Sb.,osTels95 phase transition by employing drop calorimetric method and high temperature X-ray diffractometry. Heat capacity of Sb.4osTe.sgs, in the solid state is deduced. Low and high temperature X-ray powder data are given.
Y. Feutelais, N.B. Chanh, B. Legendre et J.R. Didry, Journal of Thermal Analysis 35 (1989) 2423-2431

B0691 – Etude des propriétés thermodynamiques des alliages liquides sélénium-tellure. Partie II. Détermination des propriétés thermodynamiques par calorimétrie et étude des propriétés structurales des alliages liquides sélénium-tellure

Nous avons étudié, par calorimétrie, l'influence de la température sur l'enthalpie molaire de formation des alliages liquides (Se,Te). Les résultats expérimentaux obtenus, ainsi que ceux déduits de mesures de forces électromotrices de piles (Mouloudj et coll., Thermochim. Acta, à paraître), sont interprétés, dans un domaine de concentration limité, en nous aidant notamment d'informations d'ordre structural déjà disponibles dans la littérature et concernant les constituants purs sélénium et tellure et les alliages à l'état liquide.
N. Mouloudj, M.C. Baron and C. Petot, Thermochimica Acta 136 (1988) 103-118

B0672 – Enthalpies de mélange du système ternaire Bismuth-Antimoine-Tellure à 911 K

Les enthalpies de mélange du système Bi-Sb-Te ont été déterminées à partir de mesures de calorimétrie de chute effectuées à 911 K. Les résultats, présentés sous forme de diagramme isoenthalpique, sont comparés avec ceux déduits des modèles thermodynamiques symétriques.
Y. Feutelais, G. Morgant and B. Legendre, Thermochimica Acta 149 (1989) 33-52

B0670 – Redetermination of the phase equilibria in the system TI2Te-Ag2Te

The Tl2Te-Ag2Te system phase equilibria have been redetermined by DTA, X-ray diffraction and the measurement of thermoelectric power. The existence of the phase Tl2Te was first established and its crystallographic parameters were determined. At least four compounds are formed in the system. The crystallographic parameters of the congruently melting AgTlTe (483°C) and the incongruently melting AgTl3Te2 (382°C), Ag8Tl2Te5 (440°C) Ag5TlTe3 (446°C) and Ag9TlTe5 (504°C) were determined. The 0-50 mol% Ag2Te range of the system is non-quasi-binary and a narrow solid solution range around the AgTITe composition gives a new insight into its dimorphic transformation.
G. Brun, M. Boubali, J-C. Tedenac, R.M. Ayral, B. Legendre, Thermochimica Acta 165 (1990) 93-101

B0663 – Capacités calorifiques et diagrammes d’équilibre des phases.

M. Gambino, AFCAT (1990) 345-359

B0640 – Capacité calorifique molaire du composé Sb0,405 Te0,595 dans les états solides et liquides entre 298K et 922K

Heat capacity (Cp) of the compound Sb.4osTe.595 in solid and liquid states at constant pressure are calculated from the results of experimental "drop calorimetric" method. The heat of fusion of the compound is deduced. A phase transition in the solid state has been put in evidence.
B. Legendre, Y. Feutelais et J.R. Didry, Journal of Thermal Analysis 34 (1988) 345-357

B0639 – Etude des transitions de phase du sulfate dibasique de plomb PbSO4. 2PbO :Influence de la vitesse de montée en température et de l’histoire thermique

Basic lead sulfate, PbSO4-2PbO, was studied by means of DTA, X-ray diffraction and scanning electron microscopy. DTA runs at different heating rates showed that two kinds of thermal evolution are possible for PbSO4' 2PbO. If T<40 deg h -1, we have the "normal" process according to the following transitions: 440°C : 3(alpha-PbSO4. 2PbO) => 2(PbSO4 .PbO)+ 620°C : + PbSO4 . 4PbO => 3(beta-PbSO4 .2PbO) If T> 40 deg h-1 the beta-PbSO4 .2PbO phase appears at 440°C but is unstable and breaks down into monobasic and tetrabasic lead sulfates. Reaction enthalpies were evaluated and correlated with the cell volume variations determined by X-ray diffraction. An interpretation of the existence of two types of process is proposed.
P. Boher, P. Grégoire, P. Garnier et B.F. Mentzen, Journal of Thermal Analysis 32 (1987) 79-90

B0632 – Contribution à l’étude du diagramme des phases du système CdTe-HgTe

V. Vassiliev, M. Gambino, J.P. Bros, 16ème JEEP (1990) 183-187

B0631 – Le sytème ytterbium-plomb : capacités calorifiques et diagramme d’équilibre des phases.

M. Gambino, J.P. Bros, G. Borzone, G. Cacciamani, R. Ferro, 16ème JEEP (1990) 127-129

B0630 – Localisation de la vallée eutectique des systèmes Al-Ga-Ge, Al-Ge-Sn et Al-Ge-Si

J.M. Miane, P. Rebouillon, J. Riou, S. Spas, J.P. Bros, 16ème JEEP (1990) 149-152

B0628 – Calorimetric determination of the enthalpies of formation of liquid Ni-Ti alloys.

The enthalpies of formation of liquid Ni-Ti alloys have been measured independently with two different calorimeters, one set at 1741 and the other at 1838 K. Measurements were made within the composition range 0 < XTi < 0.5 where XTi is the mole fraction of Ti. A minimum in the compositional dependence of ?MH between XTi = 0.3 and XTi = 0.4 shows definitively that the solution is not regular. Rather there is indication that atomic packing considerations lead to the persistence of short-range order in the liquid phase above and in the vicinity of the efficiently packed intermetallic phase at Ni3Ti.
R. Lück, I. Arpshofen, B. Predel, J. F. Smith, Thermochimica Acta 131 (1988) 171-181

B0604 – Etude expérimentale des propriétés thermodynamiques des alliages liquides plomb-tellure

L'activité du plomb dans les alliages liquides (Pb, Te) a été déterminée par la méthode des FEM de piles, dans l'intervalle de température 653-1273 K et dans toute la gamme de concentration. Nous avons pu déduire de ces résultats les grandeurs thermodynamiques intégrales ?HM, ?SM et ?GM à 1200 K. De plus, nous avons mesuré par calorimétrie l'enthalpie partielle de dissolution du plomb et du tellure dans les alliages liquides à 879 K.
N. Moniri and C. Petot, Thermochimica Acta 77 (1984) 151-166

B0598 – Méthode calorimétrique de mesure des enthalpies de formation des alliages liquides à forte tension de vapeur

The heat effects corresponding to the dissolution of solid PbSe in liquid Pb-Se alloys starting from pure Pb were measured with a direct reaction calorimeter. The partial enthalpy of formation of PbSe in the melt and the integral enthalpy of formation of the Pb-PbSe system in the liquid state referred the liquid Pb and PbSe were deduced. Then, from a very simple change of reference state, and in the knowledge of the enthalpy of PbSe, the integral enthalpy of formation of Pb-Se liquid alloys with reference to pure liquid components could be derived. The results agreed very well with those obtained previously on the dissolution of Se in Pb. The method used can be applied whenever the component to be added to the bath has a high vapor pressure.
K.P. Kotchi, R. Castanet et J.C. Mathieu, Journal of Thermal Analysis 32 (1987) 1477-1486

B0566 – Capacité calorifique molaire du composé Bi.4 Te.6 dans les états solide et liquide

The heat capacities of Bi. 4 Te. 6 in the solid and liquid states are calculated from the results of the experimental "drop calorimetric" method, and the heat of fusion of the compound is deduced.
G. Morgant, C. Souleau, B. Legendre, S. Bordas, Journal of Thermal Analysis 32 (1987) 1201-1207

B0548 – Review of some metallurgical problems suitable for quantitative calorimetric treatment

A review is given of various metallurgical problems treated in the author's laboratory, for which quantitative calorimetry gave very valuable information. Measurements of thermodynamic data for phase diagram calculations, vacancies in ordered alloys, annealing of steels, and the recovery and crystallization of amorphous alloys are successively examined.
J. Hertz, Journal of Thermal Analysis 30 (1985) 1227-1240

B0535 – Evidence for gp-zone formation in an AI-3% Zn alloy

The presence of small GP-zones in an AI-3 wt% Zn solid solution aged at temperatures below 80 ~ is inferred from calorimetric reversion studies, although this composition lies outside the miscibility gap of the accepted phase diagram. The size of the zones is about 1 to 1.5 nm, as measured by high resolution electron microscopy.
A. Zahra, C.Y. Zahra, A. Charai and C. Boulesteix, Journal of Thermal Analysis 30 (1985) 671-675

B0519 – Contribution à l’étude du diagramme d’équilibre du système Ag+ Au+ Pb

S. Hassam, M. Gambino, M. Gaune-Escard, J.P. Bros, AICAT, Ferrara, (1986) 342-348

B0504 – Enthalpies de formation des alliages ternaires liquides Ag-Au-Si (Ge), Au-Cu-Si (Ge) et Cu-Ag-Si (Ge) par calorimétrie de réaction directe

R. Castanet, AICAT, Ferrara, (1986) 353-357

B0503 – Enthalpie de formation des alliages liquides Ga+In+Pb

R. Rebouillon, M. Gambino, J.P. Bros, C. Girard, R. Baret, AICAT, Ferrara, (1986) 120-124

B0481 – Influence de l’oxygène adsorbé sur la sulfatation de l’oxyde de nickel par le dioxyde de soufre

The interactions between gaseous sulfur dioxide and nickel oxide at 250° have been investigated by means of temperature-programmed desorption (TPD) and microcalorimetric techniques. Depending on the thermal treatment of the oxide, different NiO samples were prepared containing chemisorbed oxygen species, O1, O2, O3 and O4, with different energies. The calorimetric data indicated that the weakly-bound species O1 is the most reactive of the oxygen forms towards sulfur dioxide. In this case, the TPD curves (m/e = 48 and m/e = 32) show a new peak at 710° this may be correlated with the desorption of a sulfur-containing compound, probably NiSO4, created by oxidation of sulfur according to the reaction S IV => S Vl. The regeneration of the species O1 has been studied as a function of the temperature of oxygen adsorption; the most favourable temperature for the sulfation of nickel oxide appears to be about 400°.
R. Lalauze et J.C. Le Thiesse, Journal of Thermal Analysis 29 (1984) 29-39

B0478 – Etude thermodynamique du système plomb-selenium par calorimétrie

L'enthalpie de formation des alliages liquides de plomb et de sélenium a été mesurée à neuf températures par calorimétrie de réaction directe (méthode de chute) pour 0 < xSe < 0,5 et 883 < T < 1365 K. L'enthalphie de formation est fortement négative dans tout le domaine étudié. Elle est indépendante de la température pour xSe < 0,3 et augmente au contraire fortement avec elle pour 0,3 < xSe < 0,5 (?Cp,max 90 J K-1 mol-1 pour xSe = 0,5).
K.P. Kotchi, R. Castanet and J-C. Mathieu, Thermochimica Acta 76 (1984) 311-323

B0462 – The phase diagram of the system lithium-cadmium

Liquidus and solidus temperatures of a large number of Li-Cd alloys with compositions between 35 and 100 at % Cd have been determined by means of resistivity measurements and differential scanning calorimetry. The results are partly in disagreement with old literature data. According to our measurements the liquidus, which is bell-shaped, attains a maximum of 544°C for 59 at% Cd
C. van der Marel, G.J.B. Vinke, J. Hennephof and W. van der Lugt, J. Phys. Chem. Solids 43 (1982) 1013-1014

B0460 – Enthalpic and structural studies of the NiZr system

The enthalpies of formation of four phases in the NiZr system were studied by direct reaction calorimetry at high temperatures. The results for the phases Ni0.33Zr0.67, Ni0.50Zr0.50, Ni0.78Zr0.22 and Ni0.83Zr0.17 are given, discussed and compared with the calculations of Miedema and Niessen and of Watson and Bennett. The phase structures were analysed by X-ray diffraction techniques.
J.C. Gachon, M. Dirand and J. Hertz, Journal of the Less Common Metals 92 (1983) 307-315

B0459 – Etude des systèmes ternaires à base d’or et de silicium .I. Le système Au-Si-Sn

B. Legendre, C. Hancheng, A. Prince, Bulletin de la Société Chimique de France, n°1 (1985) 50-57

B0458 – Capacité calorifique de l’alliage Sn0,5 Se0,5 à l’état solide entre 375 et 1135K

La capacité calorifique de l'alliage Sn0,50Se0,50, correspondant à la formule du composé stoechiométrique SnSe à fusion congruente décrit dans la littérature, a été mesurée dans l'état solide entre 375 et 1135 K. Les mesures d'enthalpimétrie de chute conduisent à la définition de deux domaines de température, où les capacités calorifiques peuvent être calculées avec précision: T 762 K, Cp = 53,25 J K-1mol-1; T 839 K, Cp = 51,79 J K-1mol-1. Entre ces deux températures, la définition de Cp est mauvaise. Il ne nous semble pas possible dans ces conditions d'affirmer qu'il s'agit d'une transition du second ordre car l'analyse des fonctions ?TT0h = f(T), dans les deux domaines où elles sont définies, conduit à penser qu'il existe une variation d'enthalpie ?H° = 1600 J mol-1, s'apparentant à une enthalpie de transformation polymorphique sans qu'il soit possible de mettre en évidence une température de transition nette.
L. Baldé, B. Legendre, C. Souleau, P. Khodadad, J.R. Didry, Journal of the Less Common Metals 80 (1981) 45-50

B0457 – Données thermochimiques relatives au système thallium-selenium à 738K, 675K et 655K

G. Morgant, B. Legendre, C. Souleau, J.R. Didry, Ann. Chim. Fr. 6 (1981) 661-670

B0455 – Mischungswärmen in ternären systemen. II. Das system Ag-Sb-Te

B. Gather, R. Blachnik, Z. Metallkde 73 (1982) 245-248

B0454 – Thermodynamical interpretation of the structural and enthalpic properties of the crystallization of the Fe—B glasses

The crystallization of melt quenched Fe1-xBx glasses has been studied by means of differential enthalpic analysis. The crystallization enthalpies show that a phase separation at a microscopic scale prevails in the glasses with x < 0.2, in agreement with our previous Mössbauer results. The origin of this micro-phase separation is discussed. A tentative description of the thermodynamical properties of these glasses is proposed on the basis of our measurements and of the published data for the pure elements.
C. Cunat, M. Notin, J. Hertz, J.M. Dubois and G. Le Caer, Journal of Non-Crystalline Solids 55 (1983) 45-60

B0452 – Capacités calorifiques molaires des composés TlSe etTl2Se dans les états solide et liquide

G. Morgant, B. Legendre, C. Souleau, Ann. Chim. Fr. 7 (1982) 301-308

B0451 – The enthalpies of formation of the intermediate phases Co0.33Zr0.67,Co0.50Zr0.50, Co0.67Zr0.33 and Co0.80Zr0.20 by direct reaction calorimetry at high temperature

The enthalpies of formation of four solid phases of the Co---Zr system were measured by direct reaction calorimetry at temperatures in the neighbourhood of the phase melting points. The products were checked by X-ray diffraction and microprobe analysis. The results are described and compared with numerical data reported recently.
J.C. Gachon, M. Dirand and J. Hertz, Journal of the Less Common Metals 85 (1982) 1-9

B0450 – Remarques sur le diagramme de phases Ti-Zr: Étude microcalorimétrique de la transition alpha <=> beta

Une étude microcalorimétrique de la transformation allotropique de l'alliage équiatomique Ti-Zr a été effectuée pour des alliages de puretés différentes. Afin d'assurer les meilleures conditions expérimentales au cours de nos expériences toujours de longue durée, nous avons utilisé des cellules spécialement construites et employé les techniques de l'ultravide pour en dégazer les parois. Notre étude expérimentale met en évidence les modifications importantes des températures et du déroulement des transitions de phases en fonction d'une part de la teneur en impureté des alliages et de leur histoire thermique (pour l'alliage le plus pur ?i(alpha --> beta) = 616°C et ?i(beta --> alpha) = 600°C), d'autre part de leur pollution dans les dispositifs expérimentaux au cours d'expériences de longue durée menées à basse température dans des conditions expérimentales mauvaises. La pureté des alliages et l'histoire thermique n'ont pas d'influence sur les valeurs des chaleurs de transformation ?H, p. ex. pour l'alliage le plus pur ?Halpha --> beta = 2460 J mol-1. L'étude d'une solution solide 50Ti-50Zr chargée à 1,7 at.% N confirme les résultats obtenus par dilatométrie sur des alliages homogènes à 1 et 3 at.% N, pour lesquels nous proposons un diagramme de phase pseudobinaire (50Ti-50Zr)-N. Une exploitation pseudothéorique de nos résultats expérimentaux a abouti au calcul d'une courbe d'isoenthalpie libre des phases a et beta à partir de la méthode récemment développée par Ramachandrarao et Lele.
J-P. Auffredic, E. Etchessahar and J. Debuigne, Journal of the Less Common Metals 84 (1982) 49-64

B0427 – Thermodynamic investigation of (a transition metal + germanium or silicon) II. (Palladium + silicon) alloys

The molar enthalpy of formation ?fHm of the liquid alloys {xPd+(1-x)Si} at 1723 K was measured by direct reaction calorimetry (drop method) using a very high-temperature Setaram calorimeter. The molar entropy of formation was deduced by combining ?fHm with the molar Gibbs free energy of formation obtained by (Knudsen effusion + mass spectrometry) and published elsewhere.
R. Castanet, R. Chastel and C. Bergman, J. Chem. Thermodynamics 15 (1983) 773-777

B0411 – Le liquidus du système Al-Ga-Sb

C. Girard, JEEP, Barcelone (1983)

B0410 – Composition et entropie de fusion des mélanges eutectiques.

J.P Bros, JEEP, Barcelone (1983)

B0409 – Article relatif a GeTe

G.K. Demensky et al., Solid State Physics 23 (1981) 3387

B0408 – Calorimetric investigation of the martensitic transformation in near stoichiometric and stoichiometric Fe3Pt

G.K Demensky et al., Journal de Physique 43 (1982) 377

B0405 – Conditions de sulfatation de l’oxyde de nickel à partir du dioxyde de soufre

M. Soustelle et al., AFCAT, La Gaillarde (1983) 352

B0401 – Système Au-Ag-Si diagramme d’équilibre des phases et enthalpies de formation à 1400K et 1500K

J.P. Bros et al., AFCAT, La Gaillarde (1983) 166

B0389 – Heats of ion-exchange on dowex 50W of alkali metal cations. Thermal effects of long duration in these exchange systems

An experimental device for the calorimetric measurement of enthalpies of cation-exchange is described, giving the values of these enthalpies for K+/H+, Na+/H+, H+/Li+,K+/Li-,Na+/Li+ and K+/Na+ exchange systems on Dowex 50W with several degrees of cross-linking. Weak thermal effects of long duration have been found in these exchange processes. The influence of the exchange system and cross-linking of the resin is studied.
M. Zamora, E. Rojas and J. Algaba, Thermochimica Acta 57 (1982) 301-308

B0383 – Utilisation d’un micro-ordinateur pour la détermination par calorimétrie de Cp de matériaux métalliques

C. Cunat et al., Revue de Métallurgie (avril 1982) 177

B0378 – Calorimetric study of water vapour interaction with bismuth molybdate

G. Venturello et al., Proceedings ICTA, Kingston (Canada) (1982) 1244

B0369 – Détermination calorimétrique de l’enthalpie de formation des alliages (Al, Ba) riches en aluminum

L'enthalpie de formation des alliages (Al, Ba) a été déterminée par calorimétrie de chute à haute température. L'enthalpie de mélange des métaux liquides purs Al et Ba pour donner l'alliage liquide présente les valeurs mH(xBa =0,056; 1215 K)= -6.6 kJ mole-1 et mH(xBa =0,333; 1215 K)=-31,0 kJ mole-1. Pour mesurer l'enthalpie de formation du composé solide Al4Ba, on provoque sa précipitation dans un bain liquide (Al, Ba) par ajout de baryum pur. On trouve fH(Al0,8Ba0,2, solide, 1215 K)=-(37,11,5) kJ mole- par référence aux métaux purs pris à l'état solide.
M. Notin, B. Djamshidi, J. C. L. Gachon and J. Hertz, Thermochimica Acta 57 (1982) 57-66

B0365 – Enthalpy of formation of Al4Ca and Al2Ca and of the liquid alloys (aluminium + calcium)

The enthalpies of formation of the intermediate phases of (aluminium + calcium) were measured directly from the enthalpies of solution of Ca in liquid Al. For the reaction: 4Al(s)+Ca(s) = Al4Ca(s) we obtained ?fH(Al4Ca, s, 953 K) = -93.3 ± 1.2) kJ.mol-1, and for 2Al(s)+Ca(s) = Al2Ca(s) we found ?fH(Al2Ca, s, 1038 K) = -(100.2 ± 2.0) kJ.mol-1. For {(1 - x)Al + xCa}(1) with mole fraction x = 0.08 short-range order correlated to a ?Cp of about 20 J.K-1.mol-1 is shown in the range of temperature 950 to 1040 K.
M. Notin, J. C. Gachon and J. Hertz, J. Chem. Thermodynamics 14 (1982) 425-434

B0362 – Réactivité thermique du dioxyde de soufre sur l’oxyde de nickel

R. Lalauze et al., AFCAT, Genève (1982)

B0337 – Experimental and theoretical mixing enthalpy of binary CsCe phases : FeTi, CoTi, NiTi

J. Hertz et al., Scripta Metallurgica 15 (1981) 981

B0336 – The enthalphy of mixing of the intermediate phases in the systems FeTi, CoTi, and NiTi by direct reaction calorimetry

The enthalphy of mixing of some intermediate phases in the systems FeTi, CoTi, and NiTi have been measured by direct reaction calorimetry between 1200 and 1500 K. The method is described, the results are given and compared with available data from diagram estimations and from earlier experimental work.
J.C. Gachon, M. Notin and J. Hertz, Thermochimica Acta 48 (1981) 155-164

B0329 – The thermodynamics of the LaNi5-H2 system by differential heat flow calorimetry II: The alpha and beta single-phase regions

Simultaneous pressure-composition isotherms and partial relative molar enthalpies of hydrogen for the single-phase portions of the system LaNi5Hx with 0 x 6.4 were obtained. In absorption the system exhibits chemisorption for 0 x 0.05 with , followed by trapping for 0.05 x 0.23 with at x = 0.05 and then contains an alpha solid solution to the phase limit at x = 0.42. In desorption this phase limit is at x = 0.34. Both the alpha-(alpha + beta) and the (alpha + beta)-beta phase boundaries exhibit discontinuous changes in with single-phase ¦?¦ values of 26.5 kJ (mol H2)-1 and 38.5 kJ (mol H2)-1 respectively. The partil relative enthalpy for the beta single phase for x > 6.05 decreases slowly with increasingx.
J.J. Murray, M.L. Post and J.B. Taylor, Journal of the Less Common Metals 80 (1981) 211-219

B0328 – The thermodynamics of the LaNi5-H2 system by differential heat flow calorimetry I: Techniques; the alpha + beta two-phase region

The use of a heat flow calorimeter with the differential twin cell configuration to study intermetallic compound-hydrogen reactions is described. The techniques of calibration and operation of both the gas titration system and the calorimeter, which are required to obtain high precision enthalpies, are described and discussed. Enthalpies for the reaction in the two-phase region of the LaNi5-H2 system are independent of the overall composition but exhibit a small hysteresis with ?Habs = -32.30 ± 0.07 kJ (mol H2)-1?Hdes = 31.83 ± 0.09 kJ (mol H2)-1 where ?Habs is the enthalpy of absorption, ?Hdes is the enthalpy of desorption and the errors are the standard deviations. The value of ?Hdes is the best value for the enthalpy of reaction between equilibrium phases with a total probable error of ±0.5 kJ (mol H2)-1.
J.J. Murray, M.L. Post and J.B. Taylor, Journal of the Less Common Metals 80 (1981) 201-209

B0327 – Differential heat flow calorimetry of the hydrides of intermetallic compounds

The thermodynamic properties of selected hydrides of intermetallic compounds are measured using a gas-solid equilibration apparatus (Sievert's) coupled to a Tian-Calvet differential calorimeter. This combination allows simultaneous measurement of enthalpy changes and Gibb's energy; the differential configuration eliminates the p?V correction. The experimental technique and apparatus are briefly described and the limits to accurate measurements are discussed. Preliminary small-sample measurements of the partial molar enthalpies of hydrogen in the two-phase coexistence region of the systems LaNi5 + H2 and CaNi5 + H2 have been performed.
J.J. Murray, M.L. Post and J.B. Taylor, Journal of the Less Common Metals 73 (1980) 33-40

A2352 – Oxidation behavior at 300–1000 C of a (Mo,W)Si2-based composite containing boride

The oxidation behavior of a (Mo,W)Si2 composite with boride addition was examined at 300–1000 C for 24 h in dry O2. The oxidation kinetics was studied using a thermobalance, and the oxide scales were analyzed using a combination of electron microscopy (SEM/EDX, FIB, BIB) and XRD. Accelerated oxidation was found to occur between 500 C and 675 C, with a peak mass gain at 625 C. The rapid oxidation is attributed to the vaporization of molybdenum oxide that leaves a porous and poorly protective silica layer behind. At higher temperature (700–1000 C) a protective scale forms, consisting of a dense SiO2/ B2O3 glass
L. Ingemarsson, M. Halvarsson, K. Hellström, T. Jonsson, M. Sundberg, L.-G. Johansson, J.-E. Svensson, Intermetallics 18 (2010) 77–86

A2351 – Oxidation behavior of a Mo (Si, Al)2-based composite at 300–1000 °C

The oxidation behavior of a Mo (Si,Al)2-based composite of Mo(Si,Al)2, Al2O3 and Mo5(Si,Al)3 (Kanthal Super ER) in synthetic air was investigated. The samples were oxidized isothermally for up to 72 h at 300–1000 C using a thermobalance. The microstructure was analyzed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Auger Electron Spectroscopy (AES) depth profiling. Broad ion beam milling (BIB) was used to prepare cross-sections. Oxidation behavior depended strongly on the composition of the substrate which consisted of a Mo(Si,Al)2 matrix and the minority phases Mo5(Si,Al)3 and Al2O3. At 300–500 C the mass gains were small with parabolic kinetics, oxidation resulting in a mixture of oxides that reflects the substrate composition. At 600 and 700 C the oxide scale is thin and protective and depleted in molybdenum, a mass loss occurring due to MoO3 vaporization. At 1000 C a protective a-alumina scale forms.
L. Ingemarsson, M. Halvarsson, J. Engkvist, T. Jonsson, K. Hellström, L.-G. Johansson, J.-E. Svensson, Intermetallics 18 (2010) 633–640

A2344 – Oxidation resistance of Fe-25Al-2Ta (at.%) in air

The high-temperature oxidation behaviour of Fe–25Al–2Ta (in at.%) has been investigated between 600 and 1000 °C using thermogravimetric analysis (TGA) in synthetic air. After oxidation for 1000 h the scales were analysed by light optical microscopy (LOM), grazing incidents X-ray diffraction (GI-XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Between 600 and 800 °C thin adherent oxide scales grew according to a parabolic rate law. At 900 °C parabolic growth was observed for several hundred hours, interrupted by sudden mass gains which are probably caused by cracking of the scales, while at 1000 °C no protective scales formed. The scales are predominantly formed by Al2O3 and minor amounts of Fe2O3. While scales formed between 600 and 800 °C are still adherent after cooling to room temperature, scales formed at higher temperatures spalled during/after cooling, possibly because the Laves phase Fe2Ta formed on the sample surfaces underneath the oxide scales. Parabolic rate constants kp show that compared to other Fe–Al alloys addition of 2 at.% Ta has no detrimental effect to the excellent oxidation resistance in air between 600 and 800 °C.
A.Hotar, M.Palm, Intermetallics 18 (2010) 1390-1395

A2338 – Air oxidation of the bulk amorphous alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 studied by using a TGA

The oxidation in air of the bulk amorphous alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 in its amorphous state and the supercooled liquid state was studied in the temperature range of 588–633?K by using a thermogravimetric analyser (TGA). The oxidation kinetics of the alloy obeys the parabolic rate law during oxidation in its amorphous state as well as in the supercooled liquid state. The results were compared with those obtained in our previous study of the air oxidation of another well-known bulk alloy, Zr65Cu17.5Ni10Al7.5, in the temperature range of 591–684?K. The value of the parabolic rate constant (K) for the alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 (e.g. K=5.9× 10?9?g?cm?2?s?1/2 at 588?K) is about two orders of magnitude less than its value for the other bulk alloy Zr65Cu17.5Ni10Al7.5 (K=6.8× 10?7?g?cm?2?s?1/2 at 588?K), thus suggesting that the bulk amorphous alloy Zr46.75Ti8.25Cu7.5Ni10Be7.5 displays a better oxidation resistance in air than Zr65Cu17.5Ni10Al7.5.
Anil Dhawan, Shubhra Mathur, Rishi Vyas, K Sachdev, M Kamruddin, A K Tyagi, S K Sharma, Phys. Scr. 82 (2010) 045602

A2269 – A combined study of the oxidation mechanism and resistance of AISI D6 steel exposed at high temperature environments

In this work it is thoroughly examined the oxidation performance of D6 tool steel under isochronal and isothermal oxidations. Isochronal oxidation tests, from ambient temperature to 1000 °C, revealed the oxidation rate of the coupons at different temperatures. Four different temperatures were selected for the isothermal oxidation test, which correspond to different oxidation rates. The oxidation and the examination of the samples were accomplished by thermogravimetric analysis (TG) in air with which the mass gain of the samples due to oxidation was simultaneously acquired. The samples were, also, examined by scanning electron microscopy (SEM), in order to observe their surface before and after the oxidation tests. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for the accurate identification of the as formed oxides. The results revealed that in every case two distinct layers of oxides were formed while their composition was different, depending on the temperature of oxidation. Furthermore, the thickness of the as formed oxides is increased when the oxidation is performed at higher temperatures
G. Vourlias, D. Chaliampalias, T.T. Zorba, E. Pavlidou, P. Psyllaki, K.M. Paraskevopoulos, G. Stergioudis, K. Chrissafis, Applied Surface Science 257 (2011) 6687–6698

A2230 – Air-stable silver-coated copper particles of sub-micrometer size

Silver-coated copper particles with various silver loading were prepared by a direct liquid-to-particle conversion process in spray pyrolysis reactor system. The prepared particles were completely densified at 900 °C within a residence time of 2.1 s and had core–shell structure, of which formation mechanism was proposed. The mean diameter of particles was 0.45 ?m. Copper particles of 20 wt.% of silver loading were stable under air and 95% of copper remained as metallic copper even after 1 month of exposure to air. This enhanced air-stability contributed to the enhanced electrical property of conductive film obtained from the coated particles. The conductive film obtained from 15 wt.% of silver-coated copper particles had a sheet resistance of 1.2 m? square?1. This low resistance resulted from the lack of oxide layer and low sintering temperature of silver layer
D.S. Jung, H.M. Lee, Y.C. Kang, S.B. Park, Journal of Colloid and Interface Science 364 (2011) 574–581

A2188 – Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3 scale totally disappeared and exclusively Fe2O3 was formed, in AISI 316 stainless steel some Cr2O3 persisted and Fe3O4 was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown
K. A. Habib, M. S. Damra, J. J. Saura, I. Cervera, and J. Bellès, International Journal of Corrosion Volume 2011, Article ID 824676

A2181 – Effect of various lanthanum sol–gel coatings on the 330Cb (Fe–35Ni–18Cr–1Nb–2Si) oxidation at 900 ?C

The influence of a lanthanum sol–gel coating on the oxide scale adherence has been studied during the 330Cb (Fe–35Ni–18Cr–1Nb–2Si) oxidation at 900 °C, in air. The alloy oxidation is performed in order to generate a protective chromia scale acting as a good barrier against carburization. Argon annealing of lanthanum sol–gel coatings have been performed at various temperatures in order to find the best conditions to insure the scale adherence. Kinetic results show that lanthanum sol–gel coatings lead to a lower oxidation rate compared to blank specimens. Thermal cycling tests on lanthanum the sol–gel coated specimen show that the oxide scale formed at 900 °C, in air, is adherent.
H. Buscail,?, C. Issartel, F. Riffard, R. Rolland, S. Perrier, A. Fleurentin, C. Josse, Applied Surface Science 258 (2011) 678– 686

A2164 – Etude d’un alliage chromino-formeur comme matériau d’interconnecteur pour l’électrolyse à Haute Température

Dans les systèmes d’Electrolyse Haute Température (EHT), le matériau choisi comme interconnecteur doit avoir une bonne résistance à la corrosion sous air et sous mélange H2/H2O à 800 °C, et maintenir une bonne conductivité sur de longues durées. Dans ce cadre, l’objectif de ce travail était, d’une part, d’évaluer un alliage ferritique commercial (l’alliage K41X) comme matériau d’interconnecteur pour l’application EHT. Dans ce but, ont été mis en place des essais d’oxydation en four et en thermoblance pour accéder aux cinétiques d’oxydation, et des mesures de résistivité pour évaluer le paramètre ASR (Area Specific Resistance) à 800°C.
Sébastien Guillou, Thèse CEA/Université de Bourgogne, Décembre 2011

A2154 – Short-term oxidation resistance and degradation of Cr2AlC coating on M38G superalloy at 900–1100 C

High temperature oxidation behavior of the Cr2AlC coating was investigated at 900–1100 °C. During the oxidation, a continuous Al2O3 scale formed, resulting in the improvement of the oxidation resistance of the substrate. Meanwhile, the oxidation induced depletion of Al within the Cr2AlC coating resulted in the transformation of Cr2AlC to Cr–C phases. Compared with bulk Cr2AlC, the Cr2AlC coating possessed similar oxidation behavior, but with higher oxidation rate. This is because a great number of columnar grain boundaries existed in the as-deposited coating, through which oxygen and nitrogen could diffuse inwardly, resulting in the internal oxidation and nitridation.
J.J. Li, M.S. Li, H.M. Xiang, X.P. Lu, Y.C. Zhou, Corrosion Science 53 (2011) 3813–3820

A2150 – Oxidation behavior of MoSi2 and Mo(Si, Al)2 coated Mo-0.5Ti-0.1Zr-0.02C alloy

MoSi2 and Mo(Si, Al)2 coatings were prepared on Mo–0.5Ti–0.1Zr–0.02C alloy using pack cementation process. Oxidation studies revealed that Mo(Si, Al)2 coating had a much superior oxidation resistance in the temperature range from 400 to 900 °C, where pest disintegration of MoSi2 occurs due to internal oxidation. The growth kinetics of Al2O3 layer formed on Mo(Si, Al)2 coating was much slower than that of SiO2 layer formed on MoSi2 coatings during oxidation
S. Majumdar, I.G. Sharma, Intermetallics 19 (2011) 541-545

A2142 – On the potential of Ti50Au50 compound as a high temperature shape memory alloy

High temperature shape memory alloys have received a large interest for many years but none of the systems studied so far has led to industrial applications yet. The titanium-gold system has been reported to develop a martensitic transformation at high temperature but the previous studies did not mention about shape memory effect in a quantitative way. Here are presented first elements concerning the potential of this compound as a high temperature shape memory alloy, from the functional properties and oxidation resistance point of view. A maximum recovered compression strain of 3.9% can be obtained for an initial compression strain of 5% corresponding to a 78% shape recovery, in the range of temperature 850–950 K. A two-way shape memory effect is also reported for the first time for this compound. The oxidation of the alloy at these temperatures seems to be a limitation but its behavior around 700 K is very promising.
C. Declairieux, A. Denquin, P. Ochin, R. Portier, P. Vermaut, Intermetallics 19 (2011) 1461-1465

A2137 – Self ignition of layers of powder mixtures: Effect of solid inertants

Within the scope of risk assessment in the nuclear industries, the influence of alumina insertion on the self-ignition behavior of zirconium powder layers has been studied. A model, based on a set of partial differential equation describing the distribution of temperature and species concentrations and their evolution with time has been developed. Numerous experiments, both in static and dynamic modes, have been carried out in order to validate the model. They have notably allowed the identification of the oxidation kinetics, which is governed by the diffusion into the oxide layer and represented by Jander's model. The activation energy has been set at 97.5 kJ mol? 1. The experimental minimum ignition temperature of pure zirconium has been determined to be 213 °C, whereas the model leads to a value of 210 °C. It has also shown a good agreement with the tests performed both in static and dynamic modes at various alumina concentrations ranging from 0 to 90 wt.%. The average deviation obtained is 3.5%, which confirms the adequacy of the model. In static mode, a threshold-like behavior has been observed with a threshold level as high as 85 wt.%, whereas a more progressive increase has been obtained for the dynamic heating mode. A parametric study including especially the influences of layer porosity, oxygen partial pressure and layer dimensions has notably demonstrated the importance of the thermal effusivity and of the oxidation kinetics. The limitation due to the oxygen diffusion being predominant, the chemical reactions between nitrogen and zirconium could not be neglected in the lower part of the dust layers. This model allows a good visualization of the ignition process. Thus, it enables the estimation of the ignition delay and temperature, parameters which are essential to evaluate quantitatively the ignition risk of such powders and to propose adequate prevention and protection means.
David Bideau, Olivier Dufaud, Fabienne Le Guyadec, Laurent Perrin, Xavier Genin, Jean-Pierre Corriou, Audrey Caleyron, Powder Technology 209 (2011) 81–91

A2133 – A novel C-free Co-based alloy for high temperature tooling applications

The principle failure mechanism in thixoforming dies is thermal fatigue as the mechanical loading is modest owing to a mushy feedstock. A novel C-free Co-based alloy was submitted to thermal cycling under conditions which mimic thixoforming of steels. The eutectic carbides, typical of Stellite alloys, are replaced in this alloy with Mo-rich coarse secondary phase particles dispersed predominantly at interdendritic sites. Its response to thermal cycling is remarkable with at least a threefold service life extension with respect to the Stellite 6 alloy, identified to be the best die material for steel thixoforming until today. The superior thermal fatigue performance of the present alloy is attributed to its resistance to high temperature oxidation, to a Co-based matrix free of brittle carbides and to its potential to retain its mechanical strength at elevated temperatures.
Yucel Birol, Materials Science and Engineering A 528 (2011) 1117–1124

A2099 – Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium–vanadium solution (1:1) at 75 °C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM–EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV6O15 (predominant component) and Na1.1V3O7.9 with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 °C changes the composition, optical and electrochemical properties
Metodija Najdoski, Violeta Koleva, Sani Demiri, Materials Research Bulletin 47 (2012) 737–743

A2051 – High-temperature oxidation behaviour of Zr alloyed Fe3Al-type iron aluminide

The oxidation behaviour of two Fe3Al-based Fe–Al–Cr–Zr–C alloys has been evaluated between 900 and 1200 °C. The alloys contained either (Fe,Al)2Zr Laves phase or ZrC carbide. The alloys were oxidised for up to 1000 h in synthetic air using thermogravimetric analysis (TGA). Scales that formed on the surfaces of the sample as well as cross sections were analysed by light optical microscopy (LOM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry (EDS). At 900 °C parabolic growth and low weight gains for both tested alloys were observed. The scales are predominantly formed by Al2O3 with minor amounts of ZrO2. Some Fe2O3 was observed after oxidation at 900 °C. At 1000 °C oxidation ingresses into the samples along grain boundaries due to preferential oxidation of the Zr-rich precipitates, becoming more severe at higher temperatures. Ingress of oxidation into the sample is more pronounced for the alloy containing ZrC where at 1200 °C it is not any longer limited to the carbide but extends markedly into the Fe3Al matrix.
A. Hotar, M. Palm, P. Kratochvíl, V. Vodicková, S. Daniš, Corrosion Science 63 (2012) 71–81

A2033 – Generation of vapor and concomitant plasma production in an electron-beam evaporator

Electron beam heating is a technique to generate vapor of refractory and high melting point metals. Vapor production finds application in thin film deposition and laserbased purification of materials. A strip electron-gun whose filament is heated by AC current is generally used because of larger molten pool formation and quiet evaporation. Electron-gun thus generates vapor. The incident beam of electrons is backscattered with large angular distribution. Both the electron groups, namely the primary and the backscattered electrons participate in production of plasma by electron-impact ionization. The plasma is weakly ionized (~ 0.1% degree of ionization) with ion density ~ 108 cm-3 and has low electron temperature (~ 0.3 eV). The vapor and the simultaneously produced plasma expand in the space above the target. Plasma expands by ambipolar diffusion in a transverse magnetic field while the vapor expands as a collision-less atomic beam. In this paper we study vapor and plasma formation of copper and zirconium.
A. Majumder, G. K. Sahu, S. Barauh, B. Jana, V. K. Mago, A. K. Das and K. B. Thakur, Journal of Physics: Conference Series 390 (2012) 012049

A2023 – Electroplating sludge metal recovering with vitrification using mineral powder additive

Electroplating sludge is a potential secondary metal resource. In this study, vitrification process was employed to recover the metal from plating sludge, and the mineral powder additive was used to improve the recovery efficiency of vitrification process. Plating sludge was collected from an industrial Ni electroplating workshop in Taiwan. Mineral powder composed of dolomite, limestone, and cullet was employed as the reductant additive to improve the efficiency of producing metallic ingot in the vitrification process. The metals Al, Ca, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were analyzed with an atomic adsorption spectrometer (AAS). Ni, Fe, and Cr are potential candidates for recovery using the vitrification process due to their relatively high mass content. To determine the optimal efficiency, vitrification processes were performed with additive to sludge mass ratios of 5:5, 6:4, 7:3, 8:2, and 9:1. The results indicate that the optimal metal recovery efficiency of Ni, Fe, and Cr was achieved at an additive to sludge ratio of 8:2. In addition, the toxicity characteristic leaching procedure (TCLP) test results for the slag meet the Taiwan EPA's regulated level of Cr(VI), Cr, Pb, and Cu. To examine the changes in microstructure, the crystalline phases of slag were analyzed with XRD. The XRD patterns show that the appearance of pseudowollastonite improves the metal recovery efficiency, whereas the appearance of diopside and quartz decreased efficiency. The preliminary economic analysis indicated that the vitrification was not only a feasible but also a cost-effective technology for the electroplating sludge treatment in this study. However, the practical application should further depend on the building cost of the plant and financial support from the government.
I-Cheng Chou, Yi-Ming Kuo, Chitsan Lin, Jian-Wen Wang, Chih-Ta Wang, Guo-Ping Chang-Chien, Resources, Conservation and Recycling 58 (2012) 45– 49

A2008 – Optimizing structural and compositional properties of electrodeposited ceria coatings for enhanced oxidation resistance of a nickel-based superalloy

Cathodic electrodeposition was used to generate ceria coatings onto a Ni-based superalloy substrate. The electrochemical parameters were optimized so as to obtain relatively thick but adherent films with tailored composition and microstructural features (multi-cracked network) designed for high temperature applications. Whereas the applied current density was shown to mainly influence the appearance and size of the cracks as well as the amount of oxygen vacancies, the linear trend between the deposited mass and the deposition time allowed a good control of the deposited thickness. A crystallization/diffusion thermal treatment was then applied to promote the dehydration of the deposit, thus resulting in a network of refined cracks, and in the complete crystallization of nanometric CeO2?x exhibiting either a needle-like or a quasi “foam-like” microstructure depending on the applied temperature. This also provided the establishment of an inwardly grown ?-Al2O3 scale at the substrate/coating interface expected to further increase the high temperature oxidation resistance of the coated superalloy.
B. Bouchaud, J. Balmain, G. Bonnet, F. Pedraza, Applied Surface Science, Volume 268, 1 March 2013, Pages 218–224

A1988 – Influence of various gaseous environments on SiO2 formation on the 330Cb (Fe-35Ni-18Cr-1Nb-2.15Si) alloy at 900 C

The influence of various gaseous environments on the 330Cb (Fe-35Ni-18Cr-1Nb-2.15Si) oxidation during 144 h, at 900 C, has been studied. In air, a non-adherent Mn1.5Cr1.5O4 and Cr2O3 containing scale is formed and no continuous silica scale is observed at the alloy/oxide interface. In nitrogen, the chromia scale is adherent and a continuous cristobalite subscale is detected at the alloy/oxide interface. In Ar-5 vol.% H2, the oxide scale is mainly composed of chromia and manganese chromite. A thick cristobalite scale is also present at the alloy/oxide interface. On this austenitic alloy the protective silica scale formation is promoted by low oxygen containing gaseous environments and the high silicon content.
Henri Buscail, C. Issartel, F. Riffard, R. Rolland, S. Perrier, A. Fleurentin, Corrosion Science 65 (2012) 535–541

A1963 – Zircaloy-4 and M5 high temperature oxidation and nitriding in air

For the purpose of nuclear power plant severe accident analysis, degradation of Zircaloy-4 and M5 cladding tubes in air at high temperature was investigated by thermo-gravimetric analysis, in isothermal conditions, in a 600–1200°C temperature range. Alloys were investigated either in a ‘as received’ bare state, or after steam pre-oxidation at 500°C to simulate in-reactor corrosion. At the beginning of air exposure, the oxidation rate obeys a parabolic law, characteristic of solid-state diffusion limited regime. Parabolic rate constants compare, for Zircaloy-4 as well as for M5 , with recently assessed correlations for high temperature Zircaloy-4 steam-oxidation. A thick layer of dense protective zirconia having a columnar structure forms during this diffusion-limited regime. Then, a kinetic transition (breakaway type) occurs, due to radial cracking along the columnar grain boundaries of this protective dense oxide scale. The breakaway is observed for a scale thickness that strongly increases with temperature. At the lowest temperatures, the M5 alloy appears to be breakaway-resistant, showing a delayed transition compared to Zircaloy-4. However, for both alloys, a pre-existing corrosion scale favours the transition, which occurs much earlier. The post transition kinetic regime is linear only for the lowest temperatures investigated. From 800°C, a continuously accelerated regime is observed and is associated with formation of a strongly porous non-protective oxide. A mechanism of nitrogen-assisted oxide growth, involving formation and re-oxidation of ZrN particles, as well as nitrogen associated zirconia phase transformations, is proposed to be responsible for this accelerated degradation.
C. Duriez, T. Dupont, B. Schmet, F. Enoch, Journal of Nuclear Materials 380 (2008) 30–45

A1962 – Air oxidation of Zircaloy-4 in the 600–1000 C temperature range: Modeling for ASTEC code application

Progress in the treatment of air oxidation of zirconium in severe accident (SA) codes are required for a reliable analysis of severe accidents involving air ingress. Air oxidation of zirconium can actually lead to accelerated core degradation and increased fission product release, especially for the highly-radiotoxic ruthenium. This paper presents a model to simulate air oxidation kinetics of Zircaloy-4 in the 600–1000°C temperature range. It is based on available experimental data, including separate-effect experiments performed at IRSN and at Forschungszentrum Karlsruhe. The kinetic transition, named ‘‘breakaway”, from a diffusion-controlled regime to an accelerated oxidation is taken into account in the modeling via a critical mass gain parameter. The progressive propagation of the locally initiated breakaway is modeled by a linear increase in oxidation rate with time. Finally, when breakaway propagation is completed, the oxidation rate stabilizes and the kinetics is modeled by a linear law. This new modeling is integrated in the severe accident code ASTEC, jointly developed by IRSN and GRS. Model predictions and experimental data from thermogravimetric results show good agreement for different air flow rates and for slow temperature transient conditions.
O. Coindreau, C. Duriez, S. Ederli, Journal of Nuclear Materials 405 (2010) 207–215

A1898 – Examination of Zinc coatings on Copper substrates by thermal analysis

Copper has excellent thermal conductivity and is mainly applied in electrical and machinery applications. Its main disadvantage is its poor resistance in aggressive environments which can be significantly enforced by the deposition of Zinc coatings. In this study the effect of the deposition time and temperature on the thickness and microstructure of Zinc coatings on Copper substrates by pack cementation process using a DSC apparatus, is investigated. Moreover, the oxidation performance of the coated samples has been evaluated in a high-temperature environment. Oxidation tests were accomplished by thermogravimetric measurements while the coated and oxidized samples were examined with SEM microscopy and XRD diffraction analysis. DSC results revealed that the chemical reactions, which lead to the coating formation, take place up to 300 °C while the coating thickness increases with the duration of the deposition process. The as formed coatings consist of two layers corresponding to different Cu–Zn phases. Finally the coated samples were found to be more resistant when exposed in the aggressive environment, as they begin to oxidize at significant higher temperatures than the uncoated samples. This can mainly attributed to the formation of ZnO on the surface of the coating.
G. Vourlias, D. Chaliampalias, E. Pavlidou, G. Stergioudis, K. Chrissafis, J Therm Anal Calorim, 2012

A1897 – Examination of the oxidation resistance of Cr–Mo–V tool steel by thermal analysis

In the present study, the oxidation behavior of Cr–Mo–V tool steel was examined at different temperatures in air. The examination was conducted by means of thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction (XRD). After non-isothermal oxidation from ambient temperature to 1000 °C, it was revealed that the specimen begins to oxidize over 700 °C, while over 800 °C the oxidation rate increases significantly. Finally over 900 °C, this rate has a considerable value, and the specimen’s oxidation resistance is inadequate. From these results, four different oxidation temperatures (805, 835, 865, and 895 °C) were selected for the isothermal test, as referred above, which correspond to different oxidation rates, to determine the oxidation activation energy of the Cr–Mo–V specimens. Energy dispersive X-ray spectroscopy (EDX) and XRD phase identification of the as-formed scales showed that in every case, it contains two distinguishable regions. The inner layer is a mixture of chrome and iron oxides and the outer layer contains iron oxides and is also characterized by high porosity. This phenomenon was explained by the different diffusion coefficients of every element in the steel matrix.
D. Chaliampalias, G. Vourlias, E. Pavlidou, K. Chrissafis, J Therm Anal Calorim (2012) 108, 677–684

A1880 – On the influence of the milling time in the Curie temperature of Fe56Co7Ni7Zr10B20 investigated by magnetic thermogravimetric analysis

Magnetic thermogravimetric analysis (TGM) was used to investigate the influence of the milling time (tmill) in the Curie temperature (TC) of nanocrystalline powders and of a melt-spun amorphous ribbon with composition Fe56Co7Ni7Zr10B20. The TGM analysis was carried in a continuous flow of 99.99% pure argon from room temperature up to 1250 K. A magnetic field of 100 Oe was applied throughout the measurements. Nanopowders of Fe56Co7Ni7Zr10B20 were produced by mechanical alloying the samples in an argon atmosphere for milling times ranging from 1 to 100 h. The samples were characterized by X-ray diffraction and by scanning electron microscopy. The average particle size decreased from 45.4 nm for a powder milled for 1 h to 5 nm after being milled for 100 h. Moreover, TC (=1126.4 ± 4.4 K) was found to be nearly independent of tmill while for the melt-spun amorphous ribbon it was found to be substantially smaller (TC = 482 K). This is a clear indication that TC is quite sensitive to the degree of amorphosity present in the sample. The activation energy associated to the crystallization process was estimated from DSC data by using the Kissinger’s method to be 193 kJ/mol.
G. F. Barbosa, F. L. A. Machado, A. R. Rodrigues, W. M. Azevedo, J Therm Anal Calorim (2012) 109, 825–829

A1866 – Oxidation and carburisation of model chromia-forming alloys in carbon dioxide

Materials to convey hot CO2-rich gases are needed in carbon capture technologies currently being developed. This work is aimed at investigating the factors controlling the oxidation of chromia-forming alloys in these atmospheres. To do so, model Fe–Cr and Fe–Cr–Ni alloys were exposed to Ar–CO2–H2O gas mixtures at 650 and 800 °C, and the reaction products examined using conventional metallography techniques. Carbide precipitation beneath oxide scales reflects a carbon supersaturation at the metal/oxide interface relative to the external atmosphere: as a gradient of oxygen potential is established across the growing scale, an elevated carbon activity results at the interface if the scale transmits carbon. On the basis of a local equilibrium model, measured carburisation rates and precipitate volume fractions were used to evaluate the influence of oxide composition and of the presence of H2O in the gas on carbon uptake/transport in the scales. Limited carburisation beneath Cr2O3 scales was shown by means of an analysis of subscale chromium depletion not to alter the oxide stability. The morphological evolution of Fe-rich oxide nodules formed as a result of localised Cr2O3 failure was studied in relation to the alloy ability to supply chromium to the metal/oxide interface. Application of nucleation-growth models to the kinetics of nodule development allowed the resistance of Cr2O3 scales to be evaluated in terms of nodule nucleation rates determined from experimental nodule surface coverages and specimen weight gains. The relative importance of nodule nucleation and growth in determining the overall alloy performance as a function of reaction temperature is discussed.
Thomas Gheno, Thèse CIRIMAT, Août 2012

A1864 – Oxidation of Fe-V Melts Under CO2-O2 Gas Mixtures

The oxidation mechanism of liquid Fe-V alloys with V content from 5 to 20 mass pct under different oxygen partial pressures using CO2-O2 mixtures with CO2 varying from 80 pct to 100 pct was investigated by thermogravimetric analysis between 1823 K and 1923 K (1550 °C and 1650 °C). The products after oxidation were identified by scanning electron microscopy energy-dispersive spectrograph and X-ray diffraction. The results indicate that the oxidation process can be divided into the following steps: an apparent incubation period, followed by a chemical reaction step with a transition step before the reaction, and diffusion as the last stage. At the initial stage, a period of slow mass increase was observed that could be attributed to possible oxygen dissolution in the liquid iron-vanadium coupled with the vaporization of V2O. The length of this period increased with increasing temperature as well as vanadium content in the melt and decreased with increasing oxygen partial pressure of the oxidant gas. This analysis was followed by a region of chemical oxidation. The oxidation rate increased with the increase of the O2 ratio in the CO2-O2 gas mixtures. During the final stage, the oxidation seemed to proceed with the diffusion of oxygen through the product layer to the reaction front. The Arrhenius activation energies for chemical reaction and diffusion were calculated, and kinetic equations for various steps were setup to describe the experimental results. The transition from one reaction mechanism to the next was described mathematically as mixed-control equations. Thus, uniform kinetic equations have been setup that could simulate the experimental results with good precision.
Haijuan Wang, Lidong Teng, Jiayun Zhang, SeshadriI Seetharaman, Metallurgical and Materials Transactions B, 41B, October 2010, 1042

A1862 – Kinetic Studies on Evaporation of Liquid Vanadium Oxide, VOx (Where x = 4 or 5)

As part of the Swedish National Eco-steel project, the present work was carried out with a view to study the evaporation of vanadium as V2O5 with a focus on the health hazards. The evaporation rate was followed by monitoring the mass loss from liquid V2O5 melts by thermogravimetric analysis (TGA) in the temperature range 1723 K to 1873 K (1450 C to 1600 C). The studies were carried out under three different oxygen partial pressures, viz, oxygen, air, or CO2. The experiments were carried out in the isothermal mode. The Arrhenius activation energies for the evaporation reaction in different atmospheres were calculated from the results. A mathematical model was developed in order to describe the kinetics of the evaporation process. Good agreement could be achieved between the mathematical model and the experimental results. Evaporation coefficients and enthalpies in different atmospheres were also estimated. The present results may also have implications in recovering vanadium values from different vanadium sources.
Yang Yang, Lidong Teng, SeshadriI Seetharaman, Metallurgical and Materials Transactions B, October 2012

A1861 – Oxidation Behavior of TiAl-8Nb Turbine Blade Alloy

GOOD heat-resistant and oxidation-resistant properties are essential for alloys that are used for the gas turbine blade parts of jet engine, because these parts are exposed to severe oxidizing conditions. Ni-based alloys have been used as turbine blade materials because of their good oxidation-resistant properties. However, the Ni-based alloys have relatively high densities and, thus, are less agreeable as turbine blade material in the aerospace field and car industry. Ti-based alloys, on the other hand, have high melting point and low density; however, the oxidation resistance of these alloys needs better understanding. ?-TiAl is an intermetallic alloy and has a high melting point, good oxidation, and creep-resistant properties around 1023 K due to the stable structure of crystallization. This alloy has been used in the automobile industry and in the nuclear field. However, the mechanical properties of this alloy are greatly affected by the quantity and species of additive elements. Besides, these alloys are sensitive with respect to oxidation. In recent days, serious research efforts have been made to improve the mechanical and oxidation-resistant properties of ?-TiAl alloys by additive elements. TiAl-Nb alloy, which belongs to the next generation of alloys with improved properties, is well known to have good oxidation resistance due to the addition of Nb up to 10 at. pct. Thus, this alloy can be used in applications from room temperature to 1123 K. The effect of the additive elements on the oxidation properties of TiAl has earlier been studied. However, a consideration of the relevant literature shows that the oxidation mechanism of the TiAl-Nb alloys is still not fully understood. In the present work, the oxidation behavior of the TiAl-8Nb alloy supplied by ACCESS, Germany in connection with the EU-funded project ‘‘IMPRESS’’ has been studied. The investigations have been carried out under isothermal conditions in the temperature range of 1173 to 1473 K by thermogravimetric method. The product layer was analyzed by scanning electron microscopy (SEM) and electron dispersion spectroscopy (EDS) techniques.
Lidong Teng, Daisuke Nakatomi, SeshadriI Seetharaman, Metallurgical and Materials Transactions B, Volume 38B, June 2007, 477

A1855 – Kinetics of Oxidation and Decarburization in Al-Si Transformation Induced Plasticity Steel

This research elucidates the evolution of internal oxidation, external oxidation, and decarburization and their interdependence under different gas atmospheres for a transformation induced plasticity (TRIP) steel sample. A rolled steel sample chemistry of 0.14 wt pct C, 1.8 wt pct Mn, 0.6 wt pct Si, and 1 wt pct Al is used as a case study. Thermogravimetric techniques are used to examine the net mass change in a sample during isothermal heat treatment under five different atmospheres: PH2O=PH2= 0.01, 0.06, 0.13, 0.20, and 0.32. The results show an initial mass decrease and later an increase. Scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), optical microscopy, and glancing-angle X-ray are used to quantify the microstructure and show that the samples have four distinct zones: (1) the external scale, often rich in fayalite; (2) an internally oxidized region with Al, Si, and Mn oxides in an Fe matrix; (3) a decarburized steel region, characterized by large ferrite grains and low carbon content; and (4) a relatively unaffected steel core with a structure similar to the starting material. The results show that the oxidation is predominantly internal and proceeds independently of decarburization, following a parabolic oxidation law where the parabolic rate constant is higher, as would be expected, at higher water vapor contents. Decarburization rates are slightly lower than the predicted rates based on carbon diffusion only, suggesting that the external scale might have an effect in blocking CO escape from the surface.
T.L. Baum, R.J. Fruehan, S. Sridhar, Metallurgical and Materials Transactions B, Volume 38B, April 2007, 287

A1848 – First Stages of Oxidation of Pt-Modified Nickel Aluminide Bond Coat Systems at Low Oxygen Partial Pressure

The ?-Al2O3 ? ?-Al2O3 phase transformation was investigated in thermally grown oxide formed on b-(Ni,Pt)Al bond coats during isothermal exposures at 900–1,200 °C in an argon atmosphere stream with the O2 partial pressure of 1 9 10-5 atm. Local curve fitting was used to evaluate the evolution of the parabolic rate constant, kp, using a general kinetic model (t = A + B?m + C?m2), during the first 5 h of oxidation. All net mass–gain curves exhibited deviations from the classic parabolic model, ?m = kpt‘1/2 a steady state regime was established only after 4 h of exposures, except for the sample oxidized at 1,100 °C.
J. M. Alvarado-Orozco, R. Morales-Estrella, M. S. Boldrick, J. L. Ortiz-Merino, D. G. Konitzer, G. Trapaga-Mart?nez, J. Munoz-Saldana, Oxid Met (2012) 78, 269–284

A1847 – Ore Melting and Reduction in Silicomanganese Production

The charge for silicomangansese production consists of manganese ore (often mixed with ferromanganese slag) dolomite or calcite, quartz, and in some cases, other additions. These materials have different melting properties, which have a strong effect on reduction and smelting reactions in the production of a silicomanganese alloy. This article discusses properties of Assman, Gabonese, and Companhia Vale do Rio Doce (CVRD) ores, CVRD sinter and high-carbon ferromanganese (HC FeMn) slag, and their change during silicomanganese production. The melting and reduction temperatures of these manganese sources were measured in a carbon monoxide atmosphere, using the sessile drop method and a differential thermal analysis/ thermogravimetric analysis. Equilibrium phases were analyzed using FACTSage (CRCT, Montreal, Canada and GTT, Aachen, Germany) software. Experimental investigations and an analysis of equilibrium phases revealed significant differences in the melting behavior and reduction of different manganese sources. The difference in smelting of CVRD ore and CVRD sinter was attributed to a faster reduction of sinter by the graphite substrate and carbon monoxide. The calculation of equilibrium phases in the reduction process of manganese ores using FACTSage correctly reflects the trends in the production of manganese alloys. The temperature at which the manganese oxide concentration in the slag was reduced below 10 wt pct can be assigned to the top of the coke bed in the silicomanganese furnace. This temperature was in the range 1823 K to 1883 K (1550 °C to 1610 °C).
Eli Ringdalen, Sean Gaal, Merete Tangstad, Oleg Ostrovski, Metallurgical and Materials Transactions B, Volume 41B, Décembre 2000, 1220

A1844 – Air-Oxidation Behavior of a Cu60Hf25Ti15 Bulk Metallic Glass at 375–520 °C

The oxidation behavior of a Cu60Hf25Ti15 bulk metallic glass was studied over the temperature range of 375–520 °C in dry air. The oxidation kinetics of the amorphous alloy generally followed the parabolic law at all temperatures, with an oxidation rate increasing with temperature. The oxidation rates of the amorphous alloy were much higher than those of polycrystalline pure-Cu, implying that the additions of Hf and Ti accelerated the oxidation reaction. The composition of the scales formed on the amorphous alloy was strongly temperature-dependent, since they consisted mostly of Cu4O3 and CuO with minor amounts of HfO2 at T < 450 °C, while mostly CuO with minor amounts of HfO2 and Cu2TiO3 were detected at higher temperatures. In addition, nanocrystalline Cu51Hf14 and Cu3Ti2 phases were detected on the substrate after oxidation at T > 450 °C, indicating the occurrence of phase transformation.
W. Kai, H. H. Hsieh, T. H. Ho, R. T. Huang, Y. L. Lin, Oxid Met (2007) 68, 177–192

A1842 – Investigation on Reduction of CoAl2O4 by Hydrogen Gas Using TGA

The reduction of metallic oxides is an important route for the production of metal and ceramic matrix composites for high technology applications. Experimental investigation on reduction of metallic oxides by hydrogen has special relevance in potential use of natural gas as a reducing agent. In view of this, the Department of Metallurgy, Royal Institute of Technology, has been pursuing kinetic studies on reduction of various complex metallic oxides.[1–5] The present work aims at a study of the reduction kinetics of CoAl2O4.
J.A. Bustnes, N.N. Viswanathan, Du Sichen, S. Seetharaman, Metallurgical and Materials Transactions B, Volume 31B, June 2000, 540

A1841 – The Oxidation Resistance of Copper-Aluminum Alloys at Temperatures up to 1,000°C

In this study, the high-temperature oxidation resistance of copper and copper-aluminum alloys in air was investigated using thermo-gravimetric analysis. Upon heating in air, copper starts to noticeably oxidize at temperatures above 400°C. It was found that as the temperature increased, more aluminum was required in order to protect the copper. Alloying with 4 wt.% aluminum leads to a remarkable improvement in oxidation resistance. The atmosphere used to heat the samples to the required test temperatures had a noticeable impact on the subsequent oxidation rates. When heated in argon before being oxidized, copper alloys with 3 wt.% and 4 wt.% aluminum showed excellent oxidation resistance with rates 1,000 times less than that of pure copper at 1,000°C. However, when these alloys were heated in air, they were much less effective at providing oxidation resistance.
Gabriel Plascencia, Torstein Utigard, Tanai Marín, JOM, January 2005

A1840 – About the Role of Chromium and Oxygen Ion Diffusion on the Growth Mechanism of Oxidation Films of the AISI 304 Austenitic Stainless Steel

To study the role of ion diffusion on the oxidation process of the AISI 304 austenitic stainless steel, chromium diffusion coefficients were determined in oxide films grown on this steel at 750, 800 and 850 °C, in air. The isotope 54Cr was used as a chromium tracer and the diffusion profiles were established by SIMS. The bulk diffusion coefficients are five orders of magnitude smaller than the grain boundary diffusion coefficients. It was found that the values of the chromium diffusivities are lower than the corresponding oxygen diffusivities obtained in previous work. Parabolic oxidation constants calculated as a function of the chrome and oxygen diffusivities, using Wagner0s theory, are close to those determined experimentally, which shows that the growth rate of chromia is controlled by ion diffusion, but inward oxygen diffusion plays the main role on the growth kinetics of chromia formed by the oxidation of the AISI 304 steel.
Antonio Claret Soares Sabioni, Roberto Paulo Barbosa Ramos, Vincent Ji, François Jomard, Waldemar Augusto de Almeida Macedo, Pedro Lana Gastelois, Vicente Braz Trindade, Oxid Met (2012) 78, 211–220

A1828 – Roasting of Nickel Concentrates

The oxidation of three nickel concentrates from two Canadian smelters was studied by thermogravimetric analysis. Concentrate samples were heated to 1223 K (950 °C) in inert or oxidizing atmospheres to determine the reaction behavior. By recording the mass change as well as the SO2 content in the outlet gas, the oxidation behaviors were quantified. Isothermal roasting tests were carried out on the concentrates over the temperature range of 673 K (400 °C) to 1123 K (850 °C).When heated in air, the samples gain mass as a result of sulfate formation at temperatures up to approximately 873 K (600 °C) to 973 K (700 °C), whereas at higher temperatures, the samples exhibit a large mass loss attributed to sulfate decomposition as well as direct SO2 formation by oxidation. In a 4 pct O2 gas atmosphere, significantly less sulfates were formed. Mixed reactions take place, in which some lead to mass loss and SO2 generation, and others lead to mass gain and SO2 consumption. The relative importance of the various reactions depends on the experimental conditions.
R. Pandher, T. Utigard, Metallurgical and Materials Transactions B, Volume 41B, August 2010, 780

A1827 – Sulfate Formation and Decomposition of Nickel Concentrates

Nickel sulfide concentrates from two Canadian nickel concentrators were investigated to improve the understanding of SO2 formation and release during processing. The concentrates were heated in gases of various oxygen concentrations up to 1573 K (1300 C) in a thermal gravimetric analysis unit to simulate what may take place during calcine collection and processing. The resulting SO2 gases were also measured. It was determined that during oxidation, there are competing reactions, such as 3FeS þ 5O2 ¼ Fe3O4 þ 3SO2 leading to mass loss, or 2FeS þ 5O2 þ SO2 ¼ Fe2ðSO4Þ3 causing mass gain. At temperatures up to approximately 973 K (700 C), sulfates were formed readily, whereas at higher temperatures, they would decompose, evolving SO2. By lowering the oxygen content in the surrounding gas, the sulfates decomposed more readily. In an argon or hydrogen atmosphere or in vacuum, it is possible to enhance the sulfate decomposition greatly, possibly allowing for reduced SO2 emissions from the electric furnaces.
R. Pandher, S. Thomas, D. Yu, M. Barati, T. Utigard, Metallurgical and Materials Transactions B, Volume 42B, April 2011, 291

A1826 – Oxidation Mechanism of Molybdenite Concentrate

The oxidation mechanism of a commercial molybdenum concentrate was investigated up to 650 C using thermal analysis. Upon introduction of air, the molybdenite concentrate started to lose mass due to the oxidation of MoS2 to form molybdenum oxide and SO2. After a rapid mass loss, this was followed by a period of mass gain due to the oxidation of MoO2 to MoO3. The solid-state reaction between MoS2 and MoO3 to form MoO2 was also found to take place. Initially, as air is introduced, the rate is controlled by gas-phase diffusion of oxygen to the reaction surface. With time, as the surfaces of the MoS2 particles become oxidized and the rates start to slow, MoO3 starts to form. This generally leads to a mass gain as well as a slow down in oxidation rate due to the formation of a fairly dense MoO3 product layer. The timing of the various reactions was very dependent on the actual experimental conditions such as sample mass, gas flow rate, and heating rates.
T. Utigard, Metallurgical and Materials Transactions B, Volume 40B, August 2009, 490

A1824 – The Kinetics of Oxidation of Liquid FeO-MnO-CaO-SiO2 Slags in Air

The oxidizing kinetics of the liquid FeO-MnO-CaO-SiO2 slags in air has been studied in the temperature range of 1500 K to 1600 K (1227 C to 1327 C) by using a thermogravimetric analysis (TGA). The reaction products after oxidation were analyzed by X-ray diffraction analysis (XRD). The surface topography of the obtained samples was analyzed by scanning electron microscopy (SEM). The products after oxidation showed the presence of manganese ferrite/magnetite and calcium silicate for all the samples in the experimental temperatures range. The oxidation process was developed through the following three consequent steps: (1) incubation period followed by a chemical reaction controlled stage (2) and later (3) diffusion of oxygen through the product layer. Appropriate mathematical relationships were constructed for these steps. Combining equations corresponding to the mechanism of oxidation, the experimental results were consistently reproduced, validating thereby the theoretical analysis.
Anna Semykina, Metallurgical and Materials Transactions B, Volume 43B, February 2012, 56

A1789 – Phase transformations and mechanical strength of OPC/ Slag pastes submitted to high temperatures

Ground granulated blast furnace slag (GGBFS or ‘‘slag’’) is a by product of the steel industry and is often used in combination with ordinary Portland cement (OPC) as a binder in concrete. When concrete is exposed to high temperatures, physical and chemical transformations lead to significant loss of mechanical strength. Past studies have reported changes in concrete where OPC is 100% of the binder, but there is a lack of published data on slag blended cements. This work provides better understanding of how slag blended cement pastes behave when exposed to high temperatures, when the critical transformations occur, and what the consequences in the structure of these pastes are. Thermogravimetric analysis made it possible to identify when the transformations occurred and the changes in mechanical strength in the cement paste. A unique outcome of this work is the lower damage presented by slag blended cements after exposure to high temperatures
Alessandra Mendes, Jay Sanjayan, Frank Collins, Materials and Structures (2008) 41, 345–350

A1783 – Preparation and Characterization of Mo/W Bimetallic Carbides by Using Different Synthesis Methods

Molybdenum and tungsten bimetallic oxides were synthetized according to the following methods: Pechini, coprecipitation and solid state reaction (SSR). After the characterization, those solids were carbureted at programmed temperature. The carburation process was monitored by checking the consumption of carburant hydrocarbon and CO produced. The monitoring process permits to avoid or to diminish the formation of pirolytic carbon.
Luiz C. A. Bastos, Waldinei R. Monteiro, Marisa A. Zacharias, Gilberto M. da Cruz, Jose Augusto J. Rodrigues, Catal Lett (2008) 120, 48–55

A1782 – Thermal Fatigue Testing of Plasma Transfer Arc Stellite Coatings on Hot Work Tool Steels under Steel Thixoforming Conditions

The thermal fatigue performance of Stellite 12 coating deposited on X32CrMoV33 hot work tool steel via the plasma transfer arc (PTA) process was investigated under steel thixoforming conditions. Stellite 12 coating has made a favorable impact on the thermal fatigue performance of the X32CrMoV33 hot work tool steel. The latter survived steel thixoforming conditions lasting much longer, for a total of 5000 cycles, when coated with a PTA Stellite 12 layer. This marked improvement is attributed to the higher resistance to oxidation and to temper softening of the Stellite 12 alloy. The Cr-rich oxides, which form during thermal cycling, provide adequate protection to high-temperature oxidation. In contrast to hot work tool steel, Stellite 12 alloy enjoys hardening upon thermal exposure under steel thixoforming conditions. This increase in the strength of the coating is produced by the formation of carbides and contributes to the superior thermal fatigue resistance of the Stellite 12 alloy. When the crack finally initiates, it propagates via the fracture of hard interdendritic carbides. The transformation of M7C3 to M23C6, which is more voluminous than M7C3, promotes crack propagation.
Yucel Birol, Agca B. Kayihan, Metallurgical and Materials Transactions A, Volume 42A, November 2011, 3277

A1773 – Studies on Synthesis and Characterization of Mo Based In Situ Composite by Silicothermy Co-reduction Process

The results of an in situ synthesis of refractory metal–intermetallic composite (RMIC), Mo-16Cr-4Si (wt pct) multiphase alloy and its characterization, are presented in this study. The alloy was prepared from the oxides of molybdenum and chromium by their co-reduction with Si metal powder as a reductant. The exothermic nature of these reactions resulted in the formation of consolidated composite as a product in a single step. The thermodynamic aspects of exothermic reactions were studied by thermogravimetry/differential thermal analyzer. As-reduced alloys were remelted by arc melting and heat treated to obtain a homogenous microstructure. The evolution of phases and microstructures qA studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectrum analysis. The multiphase alloy consisted of Mo3Si and discontinuous (Mo, Cr) (ss) phase with a volume percentage of 28 pct. The synthesized alloys were characterized with respect to composition, phases, microstructure, hardness, and oxidation behavior.
Bhaskar Paul, S.P. Chakraborty, Jugal Kishor, I.G. Sharma, A.K. Suri, Metallurgical and Materials Transactions B, Volume 42B, August 2011, 700

A1768 – Kinetic Studies on Hydrogen Reduction of MoO3 and Morphological Analysis of Reduced Mo Powder

The studies on hydrogen reduction of MoO3 indicated two main stages, namely, MoO3 toMoO2 and MoO2 to Mo. In both stages, temperature and time of reduction progressively increased on diluting hydrogen from 100 to 10 pct. Detailed kinetic analysis of the MoO2 to Mo stage was conducted by carrying out isothermal reduction between 625 C and 900 C by pure hydrogen. The kinetic equation was found to be g(?)= [-ln(1-?)1/n] = kt, with n ranging from 1.49 to 2.13. The rate constant k obeyed the Arrhenius temperature dependence with the associated activation energy of 136 kJ mol-1. The X-ray diffraction (XRD) analysis of the product confirmed the phases predicted by thermal analysis. The scanning electron microscope (SEM) analysis of molybdenum powder revealed the presence of a greater number of pores and cracks in the individual particles produced at lower reduction temperatures and the tendency of acquiring spherical morphology with increasing reduction temperature. Based on the studies conducted, the optimum conditions for MoO3 to Mo reduction were predicted.
S. Majumdar, I.G. Sharma, I. Samajdar, P. Bhargava, Metallurgical and Materials Transactions B, Volume 39B, June 2008, 431

A1766 – Cyclic Oxidation Behavior of Simulated Post-Weld Heat-Treated P91

For long-term service life it is desirable that the high-temperature components posses slow-growing oxide scale. The growth and degradation of the oxide scale on P91 were studied by a thermal cycling method. The oxidation temperature was 780 °C and the duration of each cycle was 2 h. The mass gain and integrity of the scale was examined using a thermogravimetric balance. Any lack of integrity is monitored by the transient mass gain associated with the exposure of fresh surface. The scale retained the integrity throughout 100 cycles. Post-oxidation examination was carried out by scanning electron microscopy, energy dispersive spectroscopy and laser Raman spectroscopy. The nature of the scale was characterized and the reason for the compositional segregation is analyzed.
S. Rajendran Pillai, R.K. Dayal, Journal of Materials Engineering and Performance, Volume 20(7) October 2011—1285

A1765 – Cyclic Oxidation of P91 by Thermogravimetry and Investigation of Integrity of Scale by ‘‘Transient-Mass-Gain’’ Method

The growth and degradation of the oxide scale on modified 9Cr–1Mo ferritic steel was studied at 1123 K using a thermogravimetric balance by employing the ‘‘transient-mass-gain method’’ in conjunction with the adaptation of a cyclic-oxidation procedure. The total duration of the oxidation was 1000 h. The experiment revealed that the cracking of the scale was initiated when the average thickness was 72 lm. Spallation occurred when the average thickness was 75 lm. The rate of spallation was found to be enhanced as the scale thickens and attained a higher rate after 90 lm. The rate constants for the different stages of oxidation were found to be different. The specimen was examined by SEM, EDS and XRD. The scale morphology revealed outwardly protruded growth, a uniform adherent oxide layer and a spalled region. Four oxide phases were identified; Cr2O3, Fe2O3, (FeCr)2O3 and FeCr2O4. The spall contained more (FeCr)2O3 whereas the adherent scale was more FeCr2O4.
S. Rajendran Pillai, R. K. Dayal, Oxid Met (2008) 69, 131–142

A1754 – The oxidation behavior of Cu–Zr–Ti–base bulk metallic glasses in air at 350–500 °C

The oxidation behavior of two Cu-base bulk metallic glasses (BMGs), having compositions Cu–30Zr–10Ti and Cu–20Zr–10Ti–10Hf (in at.%), was studied over the temperature range of 350–500 °C in dry air. In general, the oxidation kinetics of both BMGs followed the parabolic rate law, with the oxidation rates increasing with increasing temperature. The addition of Hf slightly reduced the oxidation rates at 350–400 °C, while the opposite results observed at higher temperatures. It was found that the oxidation rates of both BMGs were significantly higher than those of polycrystalline pure-Cu. The scales formed on both BMG alloys were strongly composition dependent, consisting of mostly CuO/Cu2O and minor amounts of cubic-ZrO2 and ZrTiO4 for the ternary BMG, and of CuO, cubic-ZrO2, and Zr5Ti7O24 for the quaternary BMG. The formation of ternary oxides (ZrTiO4 and Zr5Ti7O24) was inferred to be responsible for the fast oxidation rates of the BMGs.
H. H. Hsieh, W. Kai, W. L. Jang, R. T. Huang, P. Y. Lee, W. H. Wang, Oxid Met (2007) 67, 179–192

A1751 – Morphological and Microstructural Aspects of Metal Dusting on 304L Stainless Steel with Different Surface Treatments

The effect of surface treatment on the susceptibility to metal dusting of 304L stainless steel (SS) exposed in a mixed gas of CO/CO2 =100/1 in the temperature ranging from 500–700 ?C was investigated. Thermogravimetric analyses (TGA) and long-term exposure tests in the above environments, followed by surface-morphological examination and cross-section chemical composition and microstructure analyses were conducted. The results showed that the decomposition of CO gas to form graphite and nano-sized carbon filaments was affected by the surface pre-treatment applied on the 304L SS. Enhanced carbon deposition but with a significant resistance to metal dusting was found on the sand-blasted 304L SS. The existence of an initial non-protective oxide on the pre-oxidized 304L SS surface, however, gave rise to the highest susceptibility to metal-dusting-associated-localized attack. The roles of different surface treatments on the reactions between 304L SS and the exposing gas environment are discussed.
Chao-Yi Lin, Chia-Hao Chang, Wen-Ta Tsai, Oxidation of Metals, Vol. 62, Nos. 3/4, October 2004

A1750 – Air Oxidation of FeCoNi-Base Equi-Molar Alloys at 800–1000°C

The oxidation behavior of FeCoNi, FeCoNiCr, and FeCoNiCrCu equi-molar alloys was studied over the temperature range 800–1000 °C in dry air. The ternary and quaternary alloys were single-phase, while the quinary alloy was two-phase. In general, the oxidation kinetics of the ternary and quinary alloys followed the two-stage parabolic rate law, with rate constants generally increasing with temperature. Conversely, three-stage parabolic kinetics were observed for the quaternary alloy at T ?900°C. The additions of Cr and Cu enhanced the oxidation resistance to a certain extent. The scales formed on all the alloys were triplex and strongly dependent on the alloy composition. In particular, on the ternary alloy, they consist of an outerlayer of CoO, an intermediate layer of Fe3O4, and an inner-layer of CoNiO2 and Fe3O4. Internal oxidation with formation of FeO precipitates was also observed for this alloy, which had a thickness increasing with temperature. The scales formed on the quaternary alloy consisted of an outer layer of Fe3O4 and CoCr2O4, an intermediate layer of FeCr2O4 and NiCr2O4, and an inner layer of Cr2O3. Finally, the scales formed on the quinary alloy are all heterophasic, consisting of an outer layer of CuO, an intermediate-layer of CuO and Fe3O4, and an inner-layer of Fe3O4, FeCr2O4, and CuCrO2. The formation of Cr2O3 on the quaternary alloy and possibly that of Cu-CrO2 on the quinary alloy was responsible for the reduction of the oxidation rates as compared to the ternary alloy.
W. Kai, W. L. Jang, R. T. Huang, C. C. Lee, H. H. Hsieh, C. F. Du, Oxidation of Metals, Vol. 63, Nos. 3/4, April 2005

A1748 – Oxidation Resistance of a Cr0.50Al0.50N Coating Prepared by Magnetron Sputtering on Alloy K38G

A Cr0.50Al0.50N coating has been prepared by a reactive-magnetron-sputtering method on alloy K38G. The coating possesses mainly the B1 type with a small amount of B4-type crystal structure phase. Isothermal oxidation tests were performed at 900–1,100 °C for 20 h by thermogravimetric analysis (TGA) in air. The results reveal that the coated samples have much lower mass gain than that of the bare alloy. The parabolic rate constants of the coated samples decrease by 2 orders of magnitude compared with the bare alloy at 1,000 and 1,100 °C. During the oxidation of the coated samples below 1,000 °C, the main oxide is Cr2O3, but above 1,000 °C, the scale changes to ?-Al2O3. The observed oxidation behaviors demonstrate that the Cr0.50Al0.50N coating can provide good protection against corrosion over a wide temperature range.
T. P. Li, X. H. Yin, M. S. Li, Y. C. Zhou, Oxid Met (2007) 68, 193–210

A1741 – Effect of Substrate Grain Size on the Growth, Texture and Internal Stresses of Iron Oxide Scales Forming at 450 °C

The oxidation behavior of iron polycrystals and single crystals with (110) surface orientation was studied at 450 °C. Energy-dispersive diffraction with synchrotron radiation provided in situ information regarding the evolution of stress gradients and fiber texture in the oxide scales. Within this low-temperature regime, grain boundaries caused the oxidation kinetics of polycrystalline iron to be more rapid than iron single crystals only during the first minutes of oxidation. Epitaxial growth of iron oxides occurred only on single crystal substrates during the initial oxidation. In situ stress analyses suggested that stress relief occurred invariably in the magnetite layer due to the formation of a fine-grained seam near the iron substrates. Above the magnetite and in the hematite layer, the growth stresses depend initially on volumetric strains and later on inner oxide formation and creep of the hematite.
C. Juricic, H. Pinto, D. Cardinali, M. Klaus, Ch. Genzel, A. R. Pyzalla, Oxid Met (2010) 73, 15–41

A1740 – Evolution of Microstructure and Internal Stresses in Multi-Phase Oxide Scales Grown on (110) Surfaces of Iron Single Crystals at 650 °C

The evolution of microstructure and growth stresses in oxide scales grown on a (110) iron single crystal surface at 650 °C was studied by electron backscatter diffraction and in situ energy-dispersive diffraction with synchrotron radiation. Within this high temperature regime, the oxidation kinetics and scale microstructure were not significantly different from those encountered in the oxidation of ferrous polycrystals. Thus, epitaxial strains did not determine the stress state within the oxide scale. Relevant sources of growth stresses were inferred to be volumetric differences between the iron oxides in the early stages, and later, inner oxide formation, scale consumption as well as pore formation. These sources caused time-dependent stress cycles in magnetite and wu¨stite during oxidation. In the hematite layer stress cycles did not occur and creep appeared to be the predominant stress relieving mechanism. On cooling, the differences in thermal expansion caused residual stress gradients through the oxide scale.
C. Juricic, H. Pinto, D. Cardinali, M. Klaus, Ch. Genzel, A. R. Pyzalla, Oxid Met (2010) 73, 115–138

A1739 – Effect of Zr Additions on the Oxidation Kinetics of FeCrAlY Alloys in Low and High pO2 Gases

Alloys of nominal composition Fe-20Cr-5Al-0.05Y (mass pct) with and without a 0.03 pct Zr addition were isothermally oxidized at temperatures of 1473 to 1573 K (1200 to 1300 °C) in both flowing Ar-O2 and Ar-H2-H2O. Continuous thermogravimetric (TG) measurements of oxygen uptake showed the rates to be faster in both gases for Zr-containing than for the Zr-free alloy. Scale growth on the Zr-bearing alloy by inward oxygen diffusion is accelerated by the fine alumina grain size and the formation of elongated zirconia particles in the two-phase scales. Zirconia formation ceases when the supply of metal in the thin alloy substrate is exhausted, and subsequent single-phase alumina growth proceeds at a slower rate. A simple diffusion model is shown to account semiquantitatively for zirconium enrichment in alumina scales. The presence of hydrogen modifies both oxygen transport in the scale and its permeability in the alloy.
D.J. Young, D. Naumenko, E. Wessel, L. Singheiser, W.J. Quadakkers, Metallurgical and Materials Transactions A, Volume 42A, May 2011—1173

A1738 – Effect of Water Vapor on High Temperature Oxidation of FeCr Alloys

The suppression of protective chromia scale formation in water vapor containing service environments limits in many cases the upper application temperature of high-Cr martensitic and ferritic steels. The present paper discusses the mechanisms which are responsible for this technologically important effect, using results of oxidation tests with two types of FeCr model alloys in Ar-O2, Ar-O2-H2O, and Ar(-H2)-H2O mixtures. The data shows that in atmospheres with a high ratio of water vapor to oxygen, Cr exhibits a higher tendency to become internally oxidized than in dry Ar-O2, or e.g. air. Contrary to previous studies which showed the presence of water vapor to affect transport processes in the scale and/or to enhance formation of volatile Cr species, the present results thus reveal that the presence of water vapor also affects the transport processes in the alloy, likely by incorporation of hydrogen. INTR
W.J. Quadakkers, J. ?urek, M. Hänsel, JOM, Vol. 61 No. 7, 44-50

A1737 – The Effect of Water Vapor on Selective Oxidation of Fe–Cr Alloys

Binary Fe–Cr alloys containing 10 and 20 mass% Cr were studied with respect to isothermal oxidation behavior at 900 and 1,050 °C in Ar–20%O2, Ar–7%H2O and Ar–4%H2-7%H2O. Thermogravimetric analyses in combination with analytical studies using SEM/EDX and Raman Spectroscopy revealed, that in atmospheres in which water vapor is the source of oxygen, Cr exhibits a higher tendency to become internally oxidized than in the Ar–O2 gas. Contrary to previous studies which showed the presence of water vapor to affect transport processes in the scale, the present results thus reveal that the presence of water vapor also affects the transport processes in the alloy. This mechanism is an ‘‘easy’’ explanation of the frequently observed effect that Fe–Cr alloys with intermediate Cr contents (e.g. 10–20%, depending on temperature) exhibit protective chromia-rich scale formation in dry gases but breakaway type Fe-rich oxides in wet gases, provided the oxygen partial pressure is sufficiently high for Fe to become oxidized.
E. Essuman, G. H. Meier, J. Zurek, M. Hänsel, W. J. Quadakkers, Oxid Met (2008) 69, 143–162

A1735 – Oxidation of Orthorhombic Titanium Aluminide TI-22AL-25NB in Air between 650 and 1000 °C

The oxidation behavior of orthorhombic titanium aluminide alloy Ti-22Al-25Nb was studied in air between 650 and 1000 °C by isothermal thermogravimetry and postoxidation scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction. Microhardness measurements were performed after exposure to gage hardening due to nitrogen and oxygen ingress. The parabolic rate constant of Ti-22Al-25Nb was of the same order as conventional titanium alloys and Ti3Al-based titanium aluminides at and below 750 °C. Between 800 and 1000 °C, the oxidation resistance of Ti-22Al-25Nb was as good as that of g-TiAl based aluminides; however, the growth rate changed from parabolic to linear after several tens of hours at 900 and 1000 °C. The mixed oxide scale consisted of TiO2, AlNbO4, and Al2O3, with TiO2 being the dominant oxide phase. Underneath the oxide scale, a nitride-containing layer formed in the temperature range investigated, and at 1000 °C, internal oxidation was observed below this layer. In all cases, oxygen diffused deeply into the subsurface zone and caused severe embrittlement. Microhardness measurements revealed that Ti-22Al-25Nb was hardened in a zone as far as 300 mm below the oxide scale when exposed to air at 900 °C for 500 h. The peak hardness depended on exposure time and reached five times the average hardness of the bulk material under the above conditions.
C. Leyens, Journal of Materials Engineering and Performance, (2001) 10, 225-230

A1733 – Investigation of the Effect of Alloying Elements and Water Vapor Contents on the Oxidation and Decarburization of Transformation-Induced Plasticity Steels

The present research deals with an investigation of the effect of alloying element additions (Si, P, and Sb) and water vapor content ðPH2O=PH2 ¼ 0:01 to 0:13Þ on the oxidation and decarburization behavior of transformation-induced plasticity (TRIP) steels in a gas mixture of 95 vol pct argon and 5 vol pct hydrogen/steam, by thermogravimetry (TG). The oxidation proceeds primarily as an internal oxidation front in the TRIP steels, but a thin external scale on the order of a micrometer thickness exists and is comprised primarily of fayalite ((Mn,Fe)2SiO4) and ((MnO)x(FeO)1ÿx. The oxidation products are distributed near the surface and along grain boundaries. A comparison between calculated and measured oxidation curves indicated that the oxidation and decarburization are independent. The results for TRIP steels, both with and without an Sb addition, indicate that increasing Si and P contents accelerate, whereas Sb addition suppresses, both decarburization and oxidation rates. Water vapor content has no obvious effect on decarburization but has a pronounced effect on oxidation, and decreasing water vapor content decreases the oxidation rates.
Z.T. Zhang, I.R. Sohn, F.S. Pettit, G.H. Meier, S. Sridhar, Metallurgical and Materials Transactions B, Volume 40B, August 2009—567

A1732 – Effect of Alloying Elements, Water Vapor Content, and Temperature on the Oxidation of Interstitial-Free Steels

The present study is an investigation of the surface and subsurface oxidation of Mn solid-solution-strengthened interstitial-free (IF) steels with the objective of elucidating the surface evolution before coating. Thermogravimetric (TG) analysis was carried out under 95 vol pct Ar+5 vol pct (H2+H2O) atmospheres with PH2O=PH2 ranging from 0.01 to 0.13 and temperatures ranging from 800 °C to 843 °C. Post-exposure characterization was carried out through scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and glancing-angle X-ray diffraction (XRD) to study the external and internal oxide evolution. The oxidation proceeds as a combination of the internal and external formation of Mn oxides. Decreasing the PH2O=PH2 ratios or temperature has the effect of decreasing the amount of oxidation, which is a combination of internal and external oxidation controlled by solid-state oxygen and manganese diffusion, respectively. External oxides are not continuous; they are instead concentrated near the intersection of alloy grain boundaries with the external surface. Internal oxides are concentrated along the grain boundaries. The effects of Sb (0.03 wt pct), B (10 ppm), P (0.04 and 0.08 wt pct), and Si (0.06 to 1.5 wt pct) on the oxidation were investigated. It is found that small amounts of Sb and B have a significant effect on decreasing both the external and internal oxidation, whereas Si and P increase the external and internal oxidation.
Z.T. Zhang, I.R. Sohn, F.S. Pettit, G.H. Meier, S. Sridhar, Metallurgical and Materials Transactions B, Volume 40B, August 2009—550

A1728 – The Effect of Water Vapour on the Oxidation of High Speed Steel, Kinetics and Scale Adhesion

An investigation has been carried out into the effects of steam on the adhesion of oxide scales grown on four different chemical compositions of high speed steels. The oxidation tests were carried out in a thermobalance at 650 °C for up to 14.4 ks. The mass gain of the specimens increased with increasing contents of water vapour, and in no case were parabolic kinetics obeyed. Increasing the alloy chromium content reduced the oxidation rate in dry conditions but increases in the V and W content had no effect. In moist conditions, the alloys containing increased Cr and W had the lowest oxidation rates followed by the alloy with increased V levels, however these effects were small. The ‘‘adhesion’’ of the oxide scale was determined using indentation with a Rockwell C diamond and the pull adhesion test to determine the interfacial toughness and the tensile strength of the oxide metal bond, respectively. Generally, the results of the investigation indicated that oxide adhesion was lowest for the specimens exposed to dry conditions, and that with increasing water vapour content, the scale was more adherent. It is noteworthy that whereas the scale formed in dry conditions spalled at the metal oxide interface, that formed in moist gas failed cohesively within the scale, mostly at the Cr spinel/magnetite interface. Examination of the fractured scale after indentation shows that the outer oxide layer became more porous as the water vapour content of the gas increased. Indentation test results showed that an increase in the V concentration was deleterious to oxide adhesion in both the dry and wet environments, whereas an increase in the Cr-content had little effect on adhesion. The results with the pull test were less clear.
M. J. Monteiro, S. R. J. Saunders, F. C. Rizzo, Oxid Met (2011) 75, 57–76

A1718 – Influence of Preoxidation and Annealing Treatments on the Isothermal Oxidation in Air at 1173 K of Cerium-Implanted EN-1.4301 Stainless Steel

Improvement of the high temperature oxidation behavior of conventional EN-1.4301 (AISI type 304) stainless steel was achieved by implanting cerium ions.Implantation was performed in samples with two different surface treatments: commercial 2B mill finishing and preoxidation in synthetic air. One set of samples was annealed after implantation in order to recover the damage induced in the crystalline structure. Results show that the implantation of Ce greatly improves the oxidation resistance at 1173 K of the EN-1.4301 grade stainless steels and that the annealing treatment after the implantation is beneficial during the subsequent oxidation. Experiments confirm the presence of spinel-type compounds and Cr2O3 and Fe–Cr mixed oxides with high Cr content in the scale, and martensite being the dominating metallic phase. Chromium depletion in the near-surface layers is also described. Results are compared to previously published data on surface modification using La and Ce by pyrolysis of aerosols.
A. Paul, S. Elmrabet, F. J. Ager, J. A. Odriozola, M. A. Respaldiza, M. F. da Silva, J. C. Soares, Oxidation of Metals, Vol. 57, Nos. 1/2, February 2002

A1716 – The Role of Silicon in the Reactive-Elements Effect on the Oxidation of Conventional Austenitic Stainless Steel

In this work we evaluate the influence of silicon on the high-temperature oxidation of austenitic stainless steels and propose a mechanism that explains the Reactive-Element Effect (REE) in terms of a synergistic action between the reactive element and the silica layer that forms in the innermost areas of the scale. To do this we have studied the oxidation at 900°C of austenitic commercial alloys (AISI-304, AISI-316 and AISI-310S) and a laboratory-designed high-silicon stainless steel (AISI-304). Lanthanum was selected as the reactive element which was surface deposited by means of ion interchange. Results obtained in this work allowed us to state that the reactive element would enhance the formation of a silica layer that shows diffusion through the scale. The reactive element also changes the expansion coefficient at the scale-alloy interface, increasing the adherence of the oxide layer to the metal.
A. Paul, R. Sanchez, O. M. Montes, J. A. Odriozola, Oxidation of Metals, Vol. 67, Nos. 1/2, February 2007

A1712 – TG/DTA study on the oxidation of nickel concentrate

The oxidation mechanism of nickel concentrate from ambient up to 1000 ?C was investigated by thermogravimetric (TG) and differential thermal analysis (DTA) to improve the understanding of the oxidation behavior of the nickel concentrate during industrial roasting. The reaction products at intermediate temperatures were analyzed by X-ray powder diffraction (XRD), SEM/EDS, electron probe micro-analysis (EPMA), and chemical analysis. A reaction scheme was deduced, in which the preferential oxidation of iron sulfide species took place in the temperature range of 350–700 ?C, forming Ni1?xS and Fe2O3. Subsequently, the resulting Ni1?xS was transformed into Ni3±xS2. Ni3±xS2 core melted at 813 ?C and accelerated its oxidation forming NiO and NiSO4. At 942 ?C, NiSO4 decomposed and the complete oxidation of the remaining nickel sulfide took place due to the absence of the protective sulfate shell. The kinetic results indicate that the diffusion of O2 through the sample bed controls the reaction rate if the bed depth is larger than approximately 125 m.
Dawei Yu, Torstein A. Utigard, Thermochimica Acta 533 (2012) 56– 65

A1693 – Initial stages of oxidation of a precipitation-hardening (PH) steel

The oxidation of a precipitation-hardening (PH) steels is a rather unexplored area. In this study an attempt is made to estimate the oxidation mechanism and the kinetics that take place up to 850°C. For this purpose specimens of the material under examination were isothermally heated at 725, 775, 800, 825, and 850°C for 12 h in O2 atmosphere. The as-treated samples were examined with SEM and XRD, while kinetics were based on thermogravimetric (TG) results. From this examination it was deduced that the oxidation of this steel is accomplished at minimum three steps, following the changes of the scale morphology and the kinetics. After 850°C although that the oxidation rate increases, the scale morphology does not change. From the calculations of the rate constant kp and the activation energy for the phenomena below 850°C, it was deduced that the oxidation phenomena during this stage provides another barrier to the deterioration of the ferrous material.
G. Vourlias, N. Pistofidis, P. Psyllaki, E. Pavlidou, K. Chrissafis, J Therm Anal Calorim (2010) 101, 893–898

A1689 – Nano-phenomena during exposure of plasma-sprayed ceria stabilised zirconia coatings to oxygen rich environments

Plasma-sprayed zirconia coatings are widely used for oxidation protection. Up-to-date, microstructural stabilisation of such coatings is mainly achieved with yttrium oxide; however recent scientific attempts indicated that ceria stabilised zirconia coatings could be a very promising alternative. In the presentwork, a coating of this kind has been deposited onto a Ni-based superalloy with the interference of a NiCrAlY bond coating by plasma spraying. Its oxidation resistancewas estimated with thermogravimetric analysis with exposure at 1100 ?C in air. The microstructure of the as-sprayed coating was studied with X-ray diffraction and electron microscopy before and after oxidation. From this examination it was deduced that ceria stabilised zirconia (CSZ) coating is rather stable at the temperature under question. However reduction of ceria takes place at larger exposure periods.
G. Vourlias, N. Pistofidis, P. Psyllaki, E. Pavlidou, G. Stergioudis, K. Chrissafis, Journal of Alloys and Compounds 483 (2009) 378–381

A1688 – Examination of the oxidation resistance of high-alloyed tool steels at elevated temperatures

In the present work the structure of two different tool steels is examined before and after oxidation up to 1000 8C in air. The materials under examination have different chromium contents. Also, the first contains vanadium (S1 tool steel) and the second tungsten (S2 tool steel) as alloying element, while the rest are common. The examination took place by thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. From this study it is deduced that the structure of the two steels, before oxidation, has several distinguishing differences mostly in the chromium distribution in the iron matrix. The oxidation tests revealed that S2 oxidizes at higher temperatures than S1, but finally, at 1000 8C, S2 tool steel has greater mass gain, because it oxidizes at a higher rate.
D. Chaliampalias, G. Vourlias, E. Pavlidou, G. Stergioudis, K. Chrissafis, Applied Surface Science 255 (2009) 6244–6251

A1687 – A combined study of the oxidation mechanism and resistance of AISI D6 steel exposed at high temperature environments

In this work it is thoroughly examined the oxidation performance of D6 tool steel under isochronal and isothermal oxidations. Isochronal oxidation tests, from ambient temperature to 1000 ?C, revealed the oxidation rate of the coupons at different temperatures. Four different temperatures were selected for the isothermal oxidation test, which correspond to different oxidation rates. The oxidation and the examination of the samples were accomplished by thermogravimetric analysis (TG) in air with which the mass gain of the samples due to oxidation was simultaneously acquired. The samples were, also, examined by scanning electron microscopy (SEM), in order to observe their surface before and after the oxidation tests. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for the accurate identification of the as formed oxides. The results revealed that in every case two distinct layers of oxides were formed while their composition was different, depending on the temperature of oxidation. Furthermore, the thickness of the as formed oxides is increased when the oxidation is performed at higher temperatures.
G. Vourlias, D. Chaliampalias, T.T. Zorba, E. Pavlidou, P. Psyllaki, K.M. Paraskevopoulos, G. Stergioudis, K. Chrissafis, Applied Surface Science 257 (2011) 6687–6698

A1686 – High temperature oxidation and corrosion in marine environments of thermal spray deposited coatings

Flame spraying is a widely used technique for depositing a great variety of materials in order to enforce themechanical or the anticorrosion characteristics of the substrate. Its high rate application is due to the rapidity of the process, its effectiveness and its low cost. In this work, flame-sprayed Al coatings are deposited on low carbon steels in order to enhance their anticorrosion performance. The main adhesion mechanism of the coating is mechanical anchorage, which can provide the necessary protection to steel used in several industrial and constructive applications. To evaluate the corrosion resistance of the coating, the as-coated samples are subjected in a salt spray chamber and in elevated temperature environments. The examination and characterization of the corroded samples is done by scanning electron microscopy and X-ray diffraction analysis. The as-formed coatings are extremely rough and have a lamellic homogeneous morphology. It is also found that Al coatings provide better protection in marine atmospheres, while at elevated temperatures a thick oxide layer is formed, which can delaminate after long oxidation periods due to its low adherence to the underlying coating, thus eliminating the substrate protection.
D. Chaliampalias, G. Vourlias, E. Pavlidou, G. Stergioudis, S. Skolianos, K. Chrissafis, Applied Surface Science 255 (2008) 3104–3111

A1679 – Plasma-sprayed YSZ coatings: Microstructural features and resistance to molten metals

Yttria Stabilized Zirconia (YSZ) coatings deposited by plasma spraying are widely used as thermal barriers onto metallic substrates, due to their attractive thermal properties and chemical inertia. In the present study, YSZ coatings were deposited onto steel substrates and their microstructure was investigated with X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The micro- and nano-scopic structural features were correlated to the performance of the coatings against corrosion by molten metals, which could simulate the industrial conditions of numerous applications. More precisely, in-scale porosity of the coatings and crystal parameters modifications were systematically examined and correlated to the corrosion behaviour in molten zinc, tin and aluminium baths for a 6 days testing period. The structural stability of the ceramic coating at high temperature, as well as the reactivity of the molten metal on the ceramic surfacewere preliminarily evaluated by thermogravimetric analysis and differential scanning calorimetry.
G. Vourlias, N. Pistofidis, P. Psyllaki, E. Pavlidou, G. Stergioudis, K. Chrissafis, Journal of Alloys and Compounds 483 (2009) 382–385

A1678 – Comparative examination of the microstructure and high temperature oxidation performance of NiCrBSi flame sprayed and pack cementation coatings

Coatings formed from NiCrBSi powder were deposited by thermal spray and pack cementation processes on low carbon steel. The microstructure and morphology of the coatings were studied by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Flame sprayed coatings exhibited high porosity and were mechanically bonded to the substrate while pack cementation coatings were more compact and chemically bonded to the substrate. The microhardness and the high temperature oxidation resistance of the coated samples were evaluated by a Vickers microhardness tester and by thermogravimetric measurements (TG), respectively. Pack cementation coatings showed higher hardness and were more protective to high temperature environments than the flame sprayed coatings
D. Chaliampalias, G. Vourlias, E. Pavlidou, S. Skolianos, K. Chrissafis, G. Stergioudis, Applied Surface Science 255 (2009) 3605–3612

A1674 – Reduction of Fe2MoO4 by Hydrogen Gas

In the present work, the reduction kinetics of iron molybdate (Fe2MoO4) by hydrogen gas was investigated by thermogravimetric analyses (TGA). Both isothermal and nonisothermal experiments were conducted. By using fine particles, very shallow powder bed, and high hydrogen flow rate, the study could be focused on the chemical reaction. The activation energy obtained from the isothermal experiments was found to be 173.5 kJ/mol, which was in reasonable agreement with the value of 158.3 kJ/mol obtained from the nonisothermal experiments. The reduction product was found to be an intermetallic compound, Fe2Mo, of microcrystalline structure.
R. Morales, I. Arvanitidis, Du Sichen, S. Seetharaman, Metallurgical and Materials Transactions B, Vol. 33B, 589, Aout 2002

A1673 – Investigation of the Oxidation Kinetics of Fe-Cr and Fe-Cr-C Melts under Controlled Oxygen Partial Pressures

In the current work, oxidation kinetics of Fe-Cr and Fe-Cr-C melts by gas mixtures containing CO2 was investigated by Thermogravimetric Analysis (TGA). The experiments were conducted keeping the melt in alumina crucibles, allowing the alloy melt to get oxidized by an oxidant gas. The oxidation rate was followed by the weight changes as a function of time. The oxidation experiments were conducted using various mixtures of O2 and CO2 with PO2 = 10ÿ2 to 104 Pa. In order to understand the mechanism of oxidation, the wetting properties between the alumina container and the alloys used in the thermogravimetric analysis (TGA) experiments and the change of the alloy drop shape during the course of the oxidation were investigated by X-ray radiography.The experiments demonstrated that the oxidation rate of Fe-Cr melt increased slightly with temperature under the current experimental conditions, but it is strongly related to the Cr-content of the alloy as well as the oxygen partial pressure in the oxidant gas mixture, both of which caused an increase in the rate. For the Fe-Cr-C system, the oxidation rate has a negative relationship with carbon content, viz. with increasing carbon, the oxidation rate of the alloy melt slightly decreased. The chemical reaction was found to be the rate determining step during the initial stages, whereas as the reaction progressed, the diffusion of oxygen ions through slag phase to the slag–melt interface was found to have a strong impact on the oxidation rate. Simulation of the oxidation kinetics using this model showed good agreement with the experimental results.
Haijuan Wang, Lidong Teng, Seshadri Seetharaman, Metallurgical and Materials Transactions B, Aout 2012

A1665 – Effects of water vapour on the oxidation of a nickel-base 625 alloy between 900 and 1,100 C

The effect of water vapour was studied on a nickel-based SY 625 alloy oxidized at 900, 1000 and 1100°C under dry and wet conditions. It appears that H2O has little effect on the oxidation rate and scale composition after 48 h. The outer scale is composed of chromia Cr2O3. At 900 and 1,000°C, NbNi4 and Ni3Mo intermetallics are found at the oxide/alloy interface. At 1,100°C, the scale is composed of an outer chromia scale and an internal CrNbO4 subscale. At this temperature the oxide scale morphology differs between dry and wet conditions. Under dry conditions the oxide scale appears to be compact but the external part of the scale partially spalled of during cooling. The oxide scales formed under wet conditions show porosities spread inside the scale and the chromia grain size is smaller. At 1,100°C scale spallation is observed under dry conditions due void accumulation in the middle part of the scale. Under wet conditions the uniform distribution of the porosities inside the scale leads to a better scale adherence.
H. Buscail, R. Rolland, C. Issartel, F. Rabaste, F. Riffard, L. Aranda, M. Vilasi, J Mater Sci (2011) 46:5903–5915

A1661 – Oxidation behaviour of arc-melted and uniaxial hot pressed MoSi2 at 500 C

Samples of MoSi2 were synthesised by arc melting and uniaxial hot pressing from different starting materials in order to distinguish the effects of sample preparations on the occurrence of the pest phenomenon, i.e. the rapid fragmentation of the pieces. The arc-melted samples presented cracks and porosities after preparation whereas the hot pressed samples were well densified (>95%). The pest appeared after no more than a few hours of exposure in air at 500 C for arc-melted samples, whereas the sintered MoSi2 samples with our experimental conditions were not at all affected. The corrosion products consisted of stoichiometric MoO3 and SiO2 mixtures. Both isothermal and cyclic oxidation measurements over long durations (>2000 h) support these results. It appears that the oxidation kinetics of hot pressed samples are governed by surface or phase boundary reactions and consequently depends on the grain size and the distribution of the initial SiO2 particles, i.e. on the MoSi2 microstructure.
S. Knittel, S. Mathieu, M. Vilasi, Intermetallics 18 (2010) 2267-2274

A1660 – Protection of cobalt-based refractory alloys by chromium deposition on surface Part II: Behaviour of the coated alloys in oxidation at high temperature

A high chromiumcontent, typically 30 wt.%, is generally considered as necessary for cobalt-based alloys to allow themto resist oxidation by hot gases. Cobalt alloys with a bulk poorer in chromiummay become resistant against high temperature oxidation if they are enriched in chromiumon surface. The aimof this second part of thework is to expose to air at 1200 °C three low-chromium cobalt-based alloys (Co–10Cr, Co–10Cr–0.25C–4.4Ta and Co–10Cr–0.5C–8.7Ta in wt.%), previously enriched in chromium on surface by pack cementation, in order to examine if the applied cementation treatments are enough to ensure a good behaviour for a long time. The initial surface enrichment in chromium of the Ta-containing alloys, characterized by a maximal content on surface of about 30 wt.% Cr and a depth of enrichment of several hundreds ofmicrometers, gives them a good resistance to oxidation at 1200 °C, despite the very low-chromiumcontent in the bulk. This is also due to the interdendritic TaC carbides which may facilitate outward diffusion of chromium during oxidation as they facilitated its inward diffusion during cementation. In contrast, the CoCr alloy, enriched in chromium in the same conditions did not display a so good oxidation behaviour.
Grégory Michel, Patrice Berthod ?, Michel Vilasi, Stéphane Mathieu, Pierre Steinmetz, Surface & Coatings Technology 205 (2011) 5241–5247

A1658 – Influence of Yttrium-Alloying Addition on the Oxidation of Alumina Formers at 1173 K

The oxidation behavior of three commercial Fe–Cr–Al alloys, Kanthal APM, Kanthal A1, and Kanthal AF (containing alloying additions of yttrium), has been investigated during isothermal exposures in air at 1173 K. After an initial transient stage, a diffusional process appears to predominantly control the oxidation kinetics of both alloys. During the transient stage, relatively important mass gains have been registered and the presence of yttrium does not seem to have a significant effect on the oxidation rate. On the contrary, the reactive element markedly influences the parabolic oxidation rate and the composition of the oxide scale. In situ X-ray diffraction (XRD) shows that yttrium promotes the transformation of transition alumina into a-Al2O3 , leading to the formation of a more protective oxide scale.
R. Cueff, H. Buscail, E. Caudron, C. Issartel, F. Riffard, Oxidation of Metals, Vol. 58, Nos. 5/6, December 2002

A1657 – Structural Characterization of Yttrium-Implanted Pure Iron and Steels Oxidized at High Temperature

Yttrium-implanted and unimplanted pure electrolytic iron, low-manganese and low-manganese–carbon steels were analyzed at high temperature (T=700°C) under oxygen partial pressure PO2 =0.04 Pa to obserûe their oxidation resistances. X-ray diffraction (XRD), reflected high-energy electron diffraction (RHEED), and glancing-angle X-ray diffraction (GAXRD) analyses per- formed on yttrium-implanted samples before high-temperature oxidation tests show that yttrium implantation promotes the formation of Y2O3 , and yttrium–iron mixed oxides (i.e., FeYO3 and Y3Fe5O12) whateûer the sample nature and Mn3O4 and YMnFeO4 , in the case of samples containing manganese. In situ, high-temperature X-ray analyses allow the obserûation of the main compounds grown on yttrium-implanted and unimplanted samples during oxidation test at high temperature. The aim of this paper is to show that FeYO3 and Fe2YO4 , in the case of pure iron, and YMnO3 , in the case of steels, seem to be responsible for the improûed corrosion resistance at high temperature.
E. Caudron, H. Buscail, Oxidation of Metals, Vol. 55, Nos. 3/4, 2001

A1656 – Water-vapor-effect on the oxidation of Fe-21.5 wt.%Cr-5.6 wt.%Al at 1000°C

Fe-21.5 wt. %Cr-5.6 wt. %Al oxidation, at 1000°C, in dry or wet oxygen shows that steam has an influence on the oxide-scale growth mechanism. Steam modifies the kinetics of early-stage oxidation. In dry oxygen, an initial fast linear regime is observed during one hour. Under wet conditions, weight-gain curves follow the same parabolic regime over the entire oxidation test. The scale structure strongly depends on the presence of steam in the gaseous environment. With dry oxygen, the scale is composed mainly of?-Al2O3 after the initial formation of?-Al2O3 identified by ESCA and RHEED. The kinetics transient stage corresponds to the necessary time for the internal part of the initial?-Al2O3 scale to transform into a continuous?-Al2O3 diffusion barrier. Under wet oxygen conditions, transient oxides are identified as (Mg, Fe) (Cr, Al)2O4, MgAl2O4 (orthorhombic), Al2O3 (hexagonal), these oxides transform into MgAl2O4 (cubic), Cr3O4, Fe2O3,?-Al2O3, with time. When water vapor does not change drastically oxidation kinetics, the induced presence of iron and chromium in the oxide scale could be responsible for weakening the protectiveness of alumina scales.
H. Buscail, S. Heinze, Ph. Dufour, J. P. Larpin, Oxidation of Metals June 1997, Volume 47, Issue 5-6, pp 445-464

A1652 – Effect of Pre-Oxidation at 800 °C on the Pitting Corrosion Resistance of the AISI 316L Stainless Steel

In situ X-ray diffraction was used to identify the oxides formed on the AISI 316L (containing 2% Mo) stainless steel during isothermal oxidation at 800 °C, in air. Good oxidation behavior was observed on this steel when considering kinetics, structural characteristics and scale adherence. It was demonstrated that molybdenum plays a protective role in that it hinders the outward iron diffusion and leads to the lower growth rate and the better scale adherence. The oxide scale was then composed of Cr2O3 with a small amount of Mn1,5Cr1,5O4 at the external interface. Pre-oxidation of the AISI 316L also improved its aqueous corrosion resistance. No pitting corrosion occured during the corrosion test. Aqueous corrosion testing also showed that the oxide scale formed at 800 °C is crack-free and still adherent after cooling to room temperature.
H. Buscail, S. El Messki, F. Riffard, S. Perrier, C. Issartel, Oxid Met (2011) 75, 27–39

A1650 – On the Oxidation and Nitridation of Chromium at 1300 °C

Chromium can be a candidate of interest as a base component for refractory alloys for high temperature applications. Few data are available about oxidation kinetic of chromium in air for temperature as high as 1300 °C. Moreover, rare papers take the nitridation of chromium into account in the description of the oxidation process or in the calculation of the kinetic constants. In the present study, global methods like thermogravimetry were linked to thickness measurements and microstructural characterisation to evaluate oxidation and nitridation contribution to weight gain. High stress levels were induced in the oxide layer during its formation. The kinetic constant associated to the nitridation, at this temperature, was one order of magnitude higher than the parabolic oxidation constant. Experiments demonstrated that the presence of nitrogen in the substrate is always a precursor to breakdown of the oxide layer and does not result from diffusion through the Cr2O3 layer.
Laurent Royer, Xavier Ledoux, Stéphane Mathieu, Pierre Steinmetz, Oxid Met (2010) 74, 79–92

A1649 – Cyclic and Isothermal Oxidation at 1,100 °C of a CVD Aluminised Directionally Solidified Ni Superalloy

CVD aluminide coatings deposited on a Directionally Solidified (DS) substrate were oxidized at 1,100 °C up to 240 h under isothermal and cyclic oxidation conditions to study the growth mechanisms of the oxide scales and the possible degradation of the coatings. The specimens were investigated using light and scanning electron (SEM) microscopy, energy-dispersive spectrometry (EDS) and X-Ray Diffraction (XRD). The results indicate that the coatings provide a much greater beneficial effect under isothermal conditions than upon cycling. The cycled specimens undergo oxide-scale spallation and increased roughening, which can derive from growth and thermal stresses as well as from the NiAl ? Ni3Al phase transformation associated with Al depletion. Under isothermal conditions, typical oxide scales formed with the appearance of some rumples. However, the origin of rumpling is uncertain from these experimental results.
B. Bouchaud, J. Balmain, F. Pedraza, Oxid Met (2008) 69, 193–210

A1648 – High-Temperature Oxidation of an Aluminized NiCr Alloy formed by a Magnetron-Sputtered Al Diffusion Coating

Aluminium diffusion coatings were obtained on Ni–20Cr substrate by sputtering an aluminium film, followed by a two stage diffusion treatment in an argon inert gas atmosphere (first stage at 600?C, second at 900 or 1100?C). Aluminides obtained at 900?C and 1100?C are close to those obtained by pack cementation process with high aluminium activity. These diffusion coatings are able to develop alumina scales during isothermal oxidation at high temperatures, whereas the untreated substrate had a chromia-forming behaviour. The weight gain recorded at 1100?C on coated sample is then smaller than the one of uncoated NiCr at 950?C. Presence of chromium was detected in the diffusion coating and Cr-rich precipitates were observed at the diffusion coating/substrate interface. After oxidation at 900?C and 1100?C, only ?-Al2O3 was revealed by XRD. An intermediate scale with a “whiskered” morphology could however be observed after 48 hr oxidation at 900?C. After 100 hr of oxidation at 1100?C, the NixAly diffusion phases were no longer detectable and the upper part of the oxide scale spalled away during cooling. Large cavities appeared at the initial location of the diffusion coating/substrate interface.
J.-M. Brossard, J. Balmain, F. Sanchette, G. Bonnet, Oxidation of Metals, Vol. 64, Nos. 1/2, August 2005

A1647 – Segregation of Neodymium in Chromia Grain-Boundaries during High-Temperature Oxidation of Neodymium Oxide-Coated Chromia-Forming Alloys

The influence of MOCVD reactive-element-oxide (REO) coatings (Nd2O3) on high-temperature, chromia-forming alloy oxidation was investigated. REO coatings decreased steel oxidation rates and greatly enhanced oxide scale adherence. Uncoated and coated F17Ti samples were oxidized over the temperature range 700–1050°C in air at atmospheric pressure. SIMS experiments were performed on oxidized-coated samples in order to determine the RE distribution through the oxide scale. Nd was distributed across the oxide layers with a higher concentration in the outer part of the scale. Transmission-electron microscopy (TEM) investigations were performed to more precisely locate the RE through the scale. Transverse cross sections, prepared on oxidized Nd2O3-coated Fe–30Cr (model system), showed that Nd, associated with Cr and O, segregated at chromia grain boundaries. It is thought that this is the main cause of the beneficial effects usually ascribed to the RE in chromia-forming alloys. The effect of chromia grain-boundary segregation on chromia growth mechanism and its influence on the reactive-element effect (REE) are discussed.
S. Chevalier, G. Bonnet, K. Przybylski, J. C. Colson, J. P. Larpin, Oxidation of Metals, Vol. 54, Nos. 5/6, 2000

A1645 – Influence of Reactive Element Oxide Coatings on the High Temperature Oxidation Behavior of Alumina-Forming Alloys

Reactive-element-oxide coatings were processed by a metal-organic chemical vapor-deposition technique on the surface of a model FeCrAl alloy. The high temperature performances of Nd2O3-, Y2O3-coated and uncoated alloys were tested in air under atmospheric pressure at 1050, 1100 and 1200?C. The coated samples did not exhibit the expected reactive-element effects since the oxidation rates were not decreased, and the oxide-scale adherence was only slightly improved. The study of the oxide-scale morphology revealed very convoluted oxide scales, except for alumina scales formed on uncoated materials at 1100 and 1200?C. Two-stage oxidation experiments showed that the reaction proceeded by a mixed anionic–cationic diffusion process; consequently, the growth of alumina within the existing alumina layer results in convoluted scales. It is proposed that the weak incorporation of the reactive elements within the thermally growing alumina scales was responsible for the limited reactive element effects, when reactive-elements were applied as oxide coatings on alumina-forming steels.
S. Chevalier, C. Nivot, J. P. Larpin, Oxidation of Metals, Vol. 61, Nos. 3/4, April 2004

A1642 – High Temperature Oxidation of the Al3Mg2 Complex Metallic Alloy

High temperature air oxidation of the Al3Mg2 complex metallic alloy was investigated on powder samples and bulk polycrystals in the temperature range 350–420 °C by thermogravimetric measurements, SEM and TEM. Oxidation at 420 °C on the polycrystalline samples comprised three successive phases characterised by linear kinetics laws. The first stage corresponded to the formation of a porous non adherent nanocrystalline MgO scale having a cauliflower morphology. A first acceleration in the kinetics law was ascribed to the nucleation and growth of MgAl2O4 crystallites which form a thin (*10 nm) film at the interface between the substrate alloy and the MgO top layer. A new linear regime was observed in the oxidation process corresponding to diffusion of magnesium through the grain boundaries of the spinel film and through the porous MgO layer. Finally, fragmentation and cracking of the scale leads to a further acceleration followed by a new linear regime.
M.-N. de Noirfontaine, G. Baldinozzi, M.-G. Barthès-Labrousse, J. Kusinski, G. Boëmare, M. Herinx, M. Feuerbacher, Oxid Met (2010) 73, 219–232

A1640 – High-Temperature Oxidation of Fe3Al and Fe3Al–Zr Intermetallics

The oxidation behavior of Fe3Al and Fe3Al–Zr intermetallic compounds was tested in synthetic air in the temperature range 900–1200 °C. The addition of Zr showed a significant effect on the high-temperature oxidation behavior. The total weight gain after 100 h oxidation of Fe3Al at 1200 °C was around three times more than that for Fe3Al–Zr materials. Zr-containing intermetallics exhibited abnormal kinetics between 900 and 1100 °C, due to the presence and transformation of transient alumina into stable a-Al2O3. Zr-doped Fe3Al oxidation behavior under cyclic tests at 1100 °C was improved by delaying the breakaway oxidation to 80 cycles, in comparison to 5 cycles on the undoped Fe3Al alloys. The oxidation improvements could be related to the segregation of Zr at alumina grain boundaries and to the presence of Zr oxide second-phase particles at the metal–oxide interface and in the external part of the alumina scale. The change of oxidation mechanisms, observed using oxygen–isotope experiments followed by secondary-ion mass spectrometry, was ascribed to Zr segregation at alumina grain boundaries.
S. Chevalier, P. Juzon, G. Borchardt, A. Galerie, K. Przybylski, J. P. Larpin, Oxid Met (2010) 73, 43–64

A1639 – Influence of the oxide content on the ignition energies of aluminium powders

Some results of determination of ignition energies for an aluminium powder with various oxide contents are presented. Common use of processes like high-speed cutting produce explosive dust clouds, so that we focused this study on hazard of metallic powders. An industrial aluminium powder has been used for this work. An original process, based on the principle of electrochemical anodisation, has been developed to increase, under control, the oxide coating of particles. The sensitivity study to spark ignition was performed in an Hartmann explosion tube of 1.3L. The Langlie test method was applied to evaluate the energies leading to a probability of ignition of 50% (E50) of the selected samples. The results confirm that the ignition energies increase with the oxide content of the powder.
G. Baudry, S. Bernard, P. Gillard, Journal of Loss Prevention in the Process Industries 20 (2007) 330–336

A1635 – Water Vapour Effect on Ferritic 4509 Steel Oxidation Between 800 and 1000 °C

The 4509 alloy (Fe–18Cr–Nb–Ti) was oxidised in dry and wet air in the 800–1000 °C temperature range. Results showed that the formation of a chromia layer acts as a good diffusion barrier under isothermal conditions at 800 and 900 °C, under 7.5 vol.% water vapour and dry air. Nevertheless, a breakaway is generally observed at 1000 °C, under wet air 7.5 vol.% H2O. It is proposed that the oxidant H?/OH- species react at the internal interface with iron in the chromium-depleted alloy zone. Wu¨ stite reacts with Cr2O3 to form FeCr2O4. Outward iron diffusion leads to Fe3O4 and Fe2O3 formation. The chromia scale was consumed by reaction with wu¨stite, but chromia also internally forms owing to a chromium oxidation process with the inner chromium-rich alloy area.
C. Issartel, H. Buscail, Y. Wang, R. Rolland, M. Vilasi, L. Aranda, Oxid Met (2011) 76, 127–147

A1630 – Kinetics of High Temperature Oxidation and Chromia Volatilization for a Binary Ni–Cr Alloy

The volatilization of the external chromia layer formed by oxidation of a Ni–30Cr alloy was studied at 1000, 1100, 1200 and 1300?C. This was done by analyzing the mass gain curves obtained by thermogravimetry on the basis of the differential equation that describes the oxidation kinetic, taking into account at each step the loss of Cr2O3 oxidized again into gaseous CrO3. The quantification of the parabolic constant and the volatilization constant was done by drawing m· dm/dt =Kp ?Kv ·m. This led to the values of both Kp and Kv for the four tested temperatures. These were compared to chromium balance sheets obtained by measuring the thicknesses of the chromia layer and chromium depletion in the alloy. A good agreement was found between the two methods. They both follow an Arrhenius law and precise values of the two constants are provided.
Patrice Berthod, Oxidation of Metals, Vol. 64, Nos. 3/4, October 2005

A1627 – Influence of Chromium Carbides on the High Temperature Oxidation Behavior and on Chromium Diffusion in Nickel-Base Alloys

Two simple cast nickel alloys Ni–30Cr–0.2C and Ni–30Cr–0.8C were oxidized at 1,000, 1,100 and 1,2008C. Their behaviors were characterized using thermogravimetry techniques and their parabolic and chromia volatilization constants were determined by analyzing the m . dm/dt versus -m curves. The constants obtained were generally in good agreement with experimental mass-gain kinetics and chromium-balance aspects. A higher carbon content i.e., a higher carbides density leads to higher values of the transient linear-oxidation constant Kl, of the parabolic constant Kp, and obviously also of the volatilization constant Kv. Chromium diffusion coefficients through the zone affected by oxidation were calculated from the oxidation kinetics and chromium gradients. They increase when the carbide density increases.
Patrice Berthod, Oxid Met (2007) 68, 77–96

A1625 – Characterisation of oxidised aluminium powder: Validation of a new anodic oxidation bench

Aluminium powder is of major interest in many applications but it presents a risk due to its high explosibility, particularly when dispersed in air. The safety is directly linked to the particles oxidation because the Minimum Ignition Energy (MIE), which is required to initiate an Al dust explosion, increases with the oxide layer thickness. This study provides a controlled method to furnish reproducible homogeneous set of powder for such safety studies. Thanks to a new experimental bench, the influence on the oxidation rate of seven treatment parameters is investigated (current density, time of treatment, acid concentration, mass of powder, particles size, stirring, neutralisation by ammonia solution). The oxide content is plotted versus the current density, the time and the acid concentration to provide reference curves for further elaboration of oxidised powder. The particles size of sieved powder is measured before and after treatment by different methods (optical and Scanning Electron Microscopes, laser measurement). A high refinement of the powder in terms of size distribution is achieved thanks to the employed sieving. The present bench and the elaborated procedure are of great interest to provide well calibrated oxidised powder directly available for safety studies. The time must be adjusted, depending on the wanted oxide content – from 2 to 18wt.% – and the other treatment parametersmust be kept constant: acid concentration (5wt.%), current density (1Adm?2), treated powder (20 g). In these conditions, the ratio of the oxide layer thickness on the particles diameter is found to be constant for a given oxide content whatever the particles size.
Nicolas Gascoin, Philippe Gillard, Guillaume Baudry, Journal of Hazardous Materials 171 (2009) 348–357

A1624 – Comparison of the High-Temperature Oxidation of Uncoated and CVD–FBR Aluminized AISI-304 Stainless Steel

Aluminide coatings were obtained by means of the CVD–FBR technique at 525°C for 1.5 hr under a reactive-gas mixture composed of 10 vol.% H2C 1 ûol.% HCl, the rest being Ar as the fluidizing inert gas. Subsequent heat treatment at temperatures to 900°C was conducted to enhance interdiffusion of the components. As a result, substoichiometric Ni–Al phases were found to form. Uncoated and coated plus heat-treated specimens were then subjected to 950°C oxidation for up to about 200 hr under isothermal conditions. The coated plus heat-treated specimens had much lower oxidation rates than the uncoated ones because of the formation of protective alumina scales. Loss of protective behavior occurred only by spalling of the alumina scales upon cooling from the oxidation temperature. The higher oxidation rates of uncoated specimens have been attributed to nodule formation and minor subsequent spalling of the oxide scale.
F. J. Perez, F. Pedraza, M. P. Hierro, J. Balmain, G. Bonnet, Oxidation of Metals, Vol. 58, Nos. 5/6, December 2002