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.