First-Principles Study of Mechanical Properties, Electronic Structure, High-Temperature and High-Pressure Properties of Au-Ga Intermetallic Compounds

Based on density functional theory, four Au-Ga intermetallic compounds (IMCs: AuGa2, Au7Ga2, AuGa, Au2Ga) are explored. First-principles calculations disclose that among them, AuGa boasts the optimal thermal stability, whereas Au7Ga2 has the poorest. The large bulk modulus of Au7Ga2 implies strong compression resistance. In contrast, AuGa2 shows inferior mechanical properties. These IMCs, with relevant values greater than 1.75 (for modulus values) and Poisson's ratios above 2.6, are ductile. Analyses of density of states suggest Au7Ga2 and Au2Ga form sturdier bonds. Debye temperature results show Au7Ga2 has the strongest interatomic bonding, Au2Ga the weakest. Thermal expansion of AuGa2/Au7Ga2 aligns with Au, and Au2Ga is less stable. This study guides medium-to-high temperature Au-Ga welding.