Experimental determination and thermodynamic calculation of the phase equilibria in the Cu-Cr-Nb and Cu-Cr-Co systems

Phase equilibria in the Cu-Cr-Nb and Cu-Cr-Co systems were, respectively, determined by metallography, X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) techniques. The thermodynamic assessments of the Cu-Cr-Nb and Cu-Cr-Co systems were carried out by using CALPHAD (CALculation of PHAse Diagrams) method on the basis of the experimental data measured by the present and previous works. The Gibbs free energies of the liquid and solid solution phases were described by the subregular solution model, and those of intermetallic compounds were described by the sublattice model. A consistent set of the thermodynamic parameters has been obtained, and the evaluated thermodynamic parameters lead to a better fit between calculated results and experimental data in both the Cu-Cr-Nb and Cu-Cr-Co systems.