Thermodynamic assessment of Mo-Ni-Ti ternary system by coupling first-principle calculations with CALPHAD approach

Abstract

A thermodynamic description of the Mo-Ni-Ti system is obtained by combining results of first-principle total energy calculations with the CALPHAD approach. The enthalpies of formation of binary intermediate phases are calculated by first-principle method employing ultra-soft pseudopotentials with plane wave basis set, which are compared with the experimental data. The energy of formation of hypothetical end-members due to the sublattice model used for modeling the ternary solubility in the binary phases Ni 3Ti, NiTi, and MoNi 3 are also calculated by first-principle method and incorporated in the modeling of those phases. Gibbs energy parameters for equilibrium phases in the Mo-Ni-Ti system are obtained by optimization of published experimental data, by combining it with thermodynamic descriptions of the limiting binaries from the literature. The liquidus projection, isothermal and vertical sections are calculated and compared with corresponding experimental information.