Phase equilibria and thermodynamic assessment of the Co–Cr binary system

The phase equilibria of the Co–Cr binary system were experimentally investigated across the whole composition range. Liquidus and solidus temperatures, measured up to 1800 °C using a differential thermal analyzer and differential scanning calorimeter, were slightly higher than those reported in the literature. The equilibrium compositions of two-phase alloys were analyzed using an electron probe microanalyzer, yielding reliable data regarding the γ(Co) + α(Cr) phase boundaries at high temperatures and ε(Co) + σ phase boundaries at low temperatures. Subsequently, a thermodynamic assessment of the Co–Cr binary system was performed using the CALPHAD technique, relying on our experimental data as well as thermodynamic property data from the literatures. The calculated Co–Cr phase diagram accurately reproduced the experimentally determined phase boundaries and thermodynamic properties, including activity, excess enthalpy, and excess Gibbs energy.