Thermodynamic assessment of Au-Pt-Ni system

This study assesses the Au-Pt-Ni system by using the calculation of phase diagrams (CALPHAD) method. Through a critical analysis of the thermodynamic properties, the thermodynamic description of the binary Pt-Ni system has been optimized to obtain a better agreement with the experimental data. Moreover, based on FCC lattices in binary Pt-Ni and ternary Au-Pt-Ni systems, first principles calculations are used to determine the enthalpies of formation of the ordered structures. Considering the solid solubility between Au, Pt, and Ni in the Au-Pt-Ni system, a four-sublattice model (Au,Pt,Ni)0.25(Au,Pt,Ni)0.25 (Au,Pt,Ni)0.25(Au,Pt,Ni)0.25 is used to describe the order-disorder transition in the Au-Pt-Ni system. Based on the parameters of the proposed optimized model, the order-disorder transition in ternary system can be reproduced satisfactorily.