CALPHAD-type thermodynamic description of phase equilibria in the Ti-W-M (M = Zr, Mo, Nb) ternary systems

Highlights: • The experimental phase equilibria data are critically evaluated. • The Ti-W-M (M = Zr, Mo, Nb) systems are assessed by CALPHAD method. • A set of self-consistent thermodynamic parameters is obtained. • The calculated results agree with the most of the experimental data. -- Abstract: Based on the thermodynamic descriptions of constitutive binary systems as well as the experimental phase equilibria data available in the literature, the Ti-W-M (M = Zr, Mo, Nb) ternary systems have been thermodynamically evaluated by the CALPHAD (CALculation of PHAse Diagram) approach. The solution phases, i.e. liquid and bcc, are described by the substitutional solution model. The binary phase W₂Zr with the solubilities of Ti is modeled using the sublattice model. A set of self-consistent thermodynamic parameters is finally obtained for each of these ternary systems. Some representative isothermal and vertical sections are calculated. Comparisons between the calculated and measured phase diagrams show that the most of experimental data are satisfactorily reproduced by the present thermodynamic descriptions.