Effects of alloying elements on the generalised stacking fault energies of Pt: a first-principles study

By adding alloying elements in Pt, the solid-solution strengthening is extensively used to improve the mechanical properties of Pt-based alloys, one of the most promising high-temperature materials due to its higher melting point. Yet the microscopic mechanism of the alloying effects on the mechanical properties of Pt is unclear. Based on a systematic study of the influence of alloying elements on the generalised stacking fault energy (GSFE) of Pt with first-principles calculations, the alloying effects on deformation mechanism and ductility of Pt are explored in this study. It is found that the alloying elements such as Y, Hf, Mo tend to decrease the intrinsic stacking fault energy (γisf) of Pt and improve its ductility, while Ru, Rh, Ir tend to increase the γisf and result in brittleness. The analysis of the electron localisation function (ELF) and density of states (DOS) indicates that the weaker or enhancer bonding between Pt atom and alloying atom at the local stacking fault area is responsible for the variation of the GSFEs, which further affects the mechanical properties of Pt-based alloys.