Thermodynamic description of phase equilibria in the C–Mo–W–N quaternary system

Abstract

The Mo–W–N and C–Mo–W ternary systems have been critically evaluated by means of the CALPHAD approach, wherein the C–Mo–W system was reassessed to ensure the model consistency. The Gibbs energies of individual phases in the ternary systems are described with corresponding models, such as substitutional solution model and sublattice model. A set of self-consistent thermodynamic parameters is obtained. Comprehensive comparisons between the calculated and reported phase diagram data show that the reliable information is satisfactorily accounted for by the present modeling. Based on the present work together with the previously reported assessments of C–Mo–N and C–W–N ternary sub-systems, a thermodynamic description of the C–Mo–W–N quaternary system is obtained and used to calculate the phase equilibria and thermodynamic stability of the hexagonal structured (Mo,W)(C,N) carbonitride phase.