Thermodynamic modeling of the Cr-Pt binary system using the cluster/site approximation coupling with first-principles energetics calculation

摘要

A thermodynamic description of Cr-Pt was developed in this study by combining first-principles calculation with the Calphad approach. The 0K enthalpies of formation of Cr_3Pt (A15), the ordered Cr_xPt_(1-x) face-centered cubic (fcc) Ll_2 compounds at A-(Pt) = 0.25 and 0.75 and Ll_0 compound at x(Pt) = 0.5 were obtained from first-principles calculation. They were used for optimizing the Gibbs energies of the corresponding phases in the Cr-Pt system. The cluster/site approximation (CSA) model was employed to model the phases in the fcc family: ordered Ll_2, Ll_0 and disordered Al (they are also referred to as the three states of fcc phase). The phase boundaries and thermodynamic properties calculated from the current thermodynamic description are in good agreement with the experimental data as well as the first-principles calculation. The stability of the three fcc states and the order-disorder transition of L1_2/A1 and L1_0/Al are reasonably described by the current description.