First-principles calculations and thermodynamic modeling of the Re–Y system with extension to the Ni–Re–Y system

The thermodynamic properties of the Re–Y binary system were modeled by complimenting the CALculation of PHAse Diagram (CALPHAD) method with first-principles calculations. Hcp and bcc solid solution phases were predicted from first-principles calculations to have positive enthalpies of mixing, indicating the existence of a miscibility gap. Heat capacity, entropy of formation, and enthalpy of formation as a function of temperature were predicted by first-principles calculations for Re2Y using the supercell method with the quasi-harmonic approximation. Together with the experimental data in the literature, a complete thermodynamic description for this binary system was developed. To predict the properties of the Ni–Re–Y system, the Ni–Re system was remodeled to be consistent with the current thermodynamic database and combined with the Ni–Y system from the literature and the Re–Y system from the current work. An isothermal section and the liquidus projection are presented.