Thermodynamic assessments of the Co–Er and V–Er systems

The Co–Er and V–Er binary systems have been thermodynamically assessed by using the CALPHAD (calculation of phase diagrams) approach on the basis of the experimental data including the thermodynamic properties and phase equilibria. Gibbs free energies of the solution phases (liquid, fcc, bcc and hcp) were modeled by the subregular solution model with the Redlich–Kister formula, and those of the intermetallic compounds (Co17Er2, Co5Er, Co7Er2, Co3Er, Co2Er, Co7Er12 and CoEr3) were described by the sublattice model. A proper set of the thermodynamic parameters has been derived for describing the Gibbs free energies of each phase in the Co–Er and V–Er systems. An agreement between the calculated results and experimental data is obtained.