Effect of Composition on Mechanical Properties of Pt-based Binary and Ternary Alloys: A First-Principles Study

In this study, we have performed a comprehensive analysis of face centered cubic (fcc) platinum binary alloys (Pt1_xMx, M = Mo, W, Re, Ru, Os, Rh, Ir, Pd, Al; x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5), focusing on their elastic constant, elastic modulus, hardness and generalized stacking fault energies, using the exact muffin-tin orbital method in combination with coherent potential approximation (EMTO-CPA). Our study has shown that the Pt1_xMx alloys with Ir, Ru, Os elements have higher elastic modulus and hardness. Moreover, Al element can lower the generalized stacking fault energies and facilitate the twinning formation. Based on these results, we provide a coherent explanation for the observed increase in strength and twinning ability in these alloys. This intriguing correlation between the two aspects opens new possibilities for the design of ternary Pt-M-X ternary alloys or Pt-based high-entropy alloys. To verify this, the twinning tendency, elastic modulus, and hardness of two representative alloys, Pt-Al-Ir and Pt-Al-Ru, were further investigated. Our results provide valuable insights into the development of advanced structural materials with high strength and ductile behavior for various engineering applications.