I. Ansara

Thermodynamic assessment of the AlNi system

The sub-lattice model is used to describe the thermodynamic behaviour of the ordered phases existing in the AlNi system. The model parameters are derived from an optimisation procedure using all available experimental data. The order-disorder transformation f.c.c.-Al:Ll2 phase is modelled using either two or four sub-lattices which are mathematically equivalent.

A binary database for III–V compound semiconductor systems

Abstract A thermodynamic database for binary III-V semiconductor systems has been compiled. It is based upon individual assessments which have been or will be published separately, but each assessment is based on the SGTE recommendation for the pure elements and uses the same solution model expression. The 15 possible binary systems between the group III elements Al, Ga and In on one hand, and the group V elements As, Sb and P are included.

Reply to the paper: “When is a compound energy not a compound energy? A critique of the 2-sublattice order/disorder model”: Of Nigel Saunders, Calphad 20 (1996) 491–499

Abstract An attempt is made to present in a more didactic manner the treatment of the order/disorder transformation expressed in the compound energy formalism. Some statements made in the article by Saunders are analysed and corrected.

A thermodynamic evaluation of the C-Fe-Ni system

Abstract An evaluation of the C-Fe-Ni system has been made using a two-sublattice subregular model for the interstitial solution phases taking into account the magnetic contribution, and an ordinary subregular solution model for the liquid phase. A set of parameter values describing the Gibbs energy of each individual phase is given.

Thermodynamic assessment of the Cr-Ta system

The optimization of the thermodynamic parameters of the various phases existing in the Cr-Ta system was performed taking into account all available thermodynamic and phase diagram data. The liquid and the two terminal bcc solid solutions were described by a Redlich-Kister equation. The Laves phases, C14 and C15-Cr2Ta, were described by the sublattice model; two different descriptions were used for each of these phases. The set of optimized parameters and the calculated phase diagrams are presented.

Critical analysis and optimization of the thermodynamic properties and phase diagrams of the III–V compounds II. The Ga-As and In-As systems

Abstract A critical assessment of thermodynamic and phase diagram data for the Ga-As and In-As systems has been performed by first carrying out a complex chemical equilibrium analysis of the conditions of measurements, then performing a critical analysis of all the experimental methods employed, and finally, after eliminating those results which seem erroneous or which show systematic deviation, and reevaluating the experimental accuracies, by optimizing the retained data together. The best self-consistent values obtained are the following: ΔH°f(GaAs, s, 298 K) =−19.54±0.30 kcal mol−1, S°298(GaAs, s) = 16.05±0.80 cal K−1 mol−1, Lf s→1 (GaAs, ) = 27.0± 0.80 kcal mol−1 at Tf = 1513.5±3 K, ΔH°f(InAs, s, 298 K) = −14.29±0.50 kcal mol−1, S°298 (InAs, s) = 17.84±0.80 cal K−1 mol−1, Lf(InAs, s→1) = 19.04±1.00 kcal mol-1 at Tf = 1212±3 K. The Gibbs energies of formation for the compounds are represented by the equations: ΔG°f(GaAs, s) = -19537+1.849T cal mol−1, ΔG°f(InAs, s) = -14291+2.257 T cal mol−1. Optimized partial pressures of In, Ga, As2, As4, InAs and GaAs molecules and phase diagrams have been obtained.

Étude thermodynamique du système ternaire gallium-indium-antimoine

Abstract With a high temperature microcalorimeter the molar excess enthalpies of mixing for liquid gallium-indium-antimony alloys have been measured at 995 K. From these results and those already obtained for the limiting binary alloys we calculated the whole set of thermodynamic functions in this ternary system. The knowledge of the Gibbs free energies of mixing and of the thermodynamic functions of the GaSb-InSb quasi-binary system enabled one to compute the liquidus of the equilibrium phase diagram on the whole concentration range. The agreement between a few published experimental data and calculated points has been found satisfactory.

Experimental and thermodynamic assessment of the FeZr system

Abstract The Gibbs energies of formation of the solution and compound phases in the FeZr system were derived from an optimization procedure using all the available experimental thermodynamic and phase diagram data. The thermodynamic description of the non-stoichiometric compounds was made using a two-sublattice model, while a Redlich-Kister polynomial was used for the solution phases. The enthalpy and temperature of fusion, as well as the temperature of invariant reactions were determined experimentally by differential thermal analysis. The results derived from the optimization are very satisfactory, despite the sparse data concerning the phase diagram and thermodynamic properties.

Contribution to the experimental and thermodynamic assessment of the AlCaFeSi system—I. AlCaFe, AlCaSi, AlFeSi and CaFeSi systems

Abstract The binary Al-Ca, Ca-Fe, Ca-Si systems and the ternary Al-Ca-Fe, Al -Fe-Si, Ca-Fe-Si systems were thermodynamically assessed. Experimental determination of the enthalpy of fusion of the ternary compounds Si2Al2Ca, Si7Al8Fe5 and Si2Al3Fe, as well as invariant temperatures in the Al-Ca-Si and Al-Fe-Si systems were derived from DTA measurements. A set of thermodynamic parameters consistent with the phase diagram, mainly in the Si-rich region, is obtained.

Thermodynamic optimisation of the Co–Nb system

Abstract The Gibbs energy descriptions of the equilibrium phases of the Co–Nb system were obtained by a computerised least-squares optimisation of the experimental thermodynamic and phase diagram data from the literature. A review of the available experimental data is presented. The modelling of phases and the optimisation procedure are described. Calculated results are compared with experimental data.