CALPHAD-type thermodynamic assessment of the Ti-Mo-Cr-V quaternary system

Based on the thermodynamic descriptions of six constitutive binary systems (Ti-Mo, Ti-Cr, Ti-V, Mo-Cr, Mo-V and Cr-V) as well as the experimental phase equilibria data of the ternary and quaternary systems available in the literature, the Ti-Mo-Cr-V quaternary system has been evaluated using the CALPHAD (CALculation of PHAse Diagram) approach. There are no ternary and quaternary compounds in this quaternary system. The solution phases, i.e. liquid, bcc ((βTi), (Mo), (Cr) and (V)) and hcp (αTi), are described by the substitutional solution model. The Laves phase αCr2Ti is modeled using the two sublattice model (Cr, Mo, Ti,V)2(Cr, Mo, Ti,V)1 with Mo and V entering both sublattices. A set of self-consistent thermodynamic parameters for the Ti-Mo-Cr-V systems is obtained. The present thermodynamic description can satisfactorily account for most of the reliable experimental data. The complete liquidus and solidus projection of the Ti-Mo-Cr, Ti-Mo-V and Mo-Cr-V systems are also presented.