C. Servant

Thermodynamic assessment of the CuFeNi system

Abstract The CuFeNi system was reassessed taking into account new experimental data in particular in the region of the ordered phase (Cu,Ni) 3 Fe. Its thermodynamic description was assessed using a four sub-lattice model, while a random substitutional solution model was used for the disordered solution phases.

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.

Thermodynamic assessment of the Fe-Nb system

The Gibbs energy of formation of the solution and compounds phases in the Fe-Nb system were derived from an optimization procedure using all the available experimental thermodynamic and phase diagram data. The thermodynamic description of the stoichiometric and non-stoichiometric compounds was made using two, three or four sublattice models, while a Redlich-Kister polynomial was used for the solution phases.

Thermodynamic reassessment of the AlN-Al2O3 system

Abstract The AlN-Al2O3 system has been reassessed due to new experimental data published in particular near the Al2O3 rich part and relative to the φ′ and δ phases. The Gibbs energy of formation of the solution and compound phases in the AlN-Al2O3 binary section were derived from an optimisation procedure using all the available experimental thermodynamic and phase diagram data. The thermodynamic description of the ordered compounds was made using the sub-lattice model, while a Redlich-Kister polynomial was used for the solution phases.

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 assessment of the SiZr system

Abstract The binary Si-Zr system was thermodynamically assessed using the available experimental information: enthalpies of formation of the liquid and compound phases, and phase diagram data. A set of thermodynamic parameters consistent with phase diagram data was obtained.

Thermodynamic modelling of the order-disorder transformation of the orthorhombic phase of the Al-Nb-Ti system

The order/disorder transformation of the orthorhombic phase of the Al-Nb-Ti system has been modelled using the sublattice formalism with the aim of representing the thermodynamic properties of the two states, ordered and disordered, with a continuous function. The molar Gibbs energy of that phase was expressed as the sum of two terms, one order-dependent and the other order-independent. Constraints between the parameters of the order-dependent term were required to ensure the stability of the disordered phase.

A thermodynamic evaluation of the Ta–V system

Abstract We present a thermodynamic study of the Ta–V system based on the Calphad–Thermocalc approach. This work is part of a broader project concerning the thermodynamic description of Ta-containing low activation steels, which were developed in the past decade for applications in fusion technology. In the binary system Ta–V, the Gibbs energy functions of the liquid, the bcc solid solution and the Laves phases were determined. Conflicting information exists in the literature concerning the possible polymorphism of the Laves phase at high temperature; a preliminary assessment of the phase diagram was made without taking into account this phenomenon. Then, the C14–C15 transition was introduced for the Laves phase. The calculated phase equilibria were compared with experimental data.

A study of the Si-rich domain of the AlCaFeSi quaternary system

Abstract Different phases appear in the elaboration of metallurgical grade silicon containing impurities such as Fe, Ca or Al. In this contribution, an attempt is made to correlate the observed phases in industrial alloys with results from a thermodynamic calculation of the quaternary system Al-Ca-Fe-Si in the Si-rich corner. In addition, differential thermal analyses as well as X-ray diffraction were performed on selected compositons of quaternary alloys, the results of which are discussed with the predicted phase diagram.