First-principles study of mechanical and thermodynamic properties of intermetallic Pt3M (M = Al, Hf, Zr, Co, Y, Sc)

Abstract Pt-based alloys are a potential high-temperature structural material. The formation of second-phase intermetallic Pt3M (M = Al, Hf, Zr, Co, Y, Sc) can further stabilize the high-temperature mechanical properties of Pt-based alloys. Here, we systematically studied the equilibrium geometry, elastic constants, electronic characteristics, Debye temperature and elastic wave velocity of intermetallic Pt3M using first-principles density function theory calculations. Elastic properties are estimated using the Voigt-Reuss-Hill approximation. Pt3Hf has the highest moduli and hardness, while Pt3Y has the lowest values. Pt3Co exhibits the strongest elastic anisotropy, while Pt3Zr is the weakest. Pt3Zr and Pt3Y have the highest and lowest Debye temperature. The metallicity and conductivity of these alloys mainly arise from d-state electronic contribution according to the electronic density of states. The charge density difference analysis shows that electrons flow from Pt to M atoms and accumulate into covalent-like bonds, which results in structural stability and mechanical anisotropy.