Structural stability, elastic anisotropy and thermophysical behavior of the Au10In3 intermetallic compound: insights from first-principles calculations

This study presents a thorough investigation of the Au10In3 intermetallic compound using density functional theory, to clarify its fundamental properties and potential applications in microelectronic packaging and high-reliability bonding. As a significant yet underexplored phase in the Au–In system, Au10In3 is systematically analyzed through first-principles calculations within a generalized gradient approximation framework, focusing on its structural stability, anisotropic elastic response and thermophysical properties. Optimized structural calculations confirm the thermodynamic stability of Au10In3, with a negative formation enthalpy of −0.138 eV/atom. Elastic constants satisfy mechanical stability criteria, establishing the compound's stability under mechanical stress. Further mechanical analysis implies ductile behavior, indicated by a high Pugh's ratio of 4.94, positive Cauchy pressures and a Poisson's ratio of 0.405. The material demonstrates Vickers hardness of 1.40 GPa and fracture toughness of 0.897 MPa·m1/2, reflecting resistance to both deformation and fracture. Elastic anisotropy of Au10In3 is estimated with several indices: symmetry-invariant universal anisotropy index (AU) is 1.21, Zener-based equivalent anisotropy parameter (Aeq) is 2.63 and logarithmic Euclidean metric (AL) is 0.48. Directional dependence of elastic moduli is illustrated through three-dimensional mappings of Young's modulus, shear modulus and Poisson's ratio, providing insight into its anisotropic behavior. In thermophysical characteristics, Au10In3 presents a Debye temperature of 151.5 K, thermal expansion coefficient of 24.3 ppm/K and lattice thermal conductivity of 0.291 W/mK, indicative of low phonon transport efficiency. Comparative analyses with related phases, Au3In and Au3In2, highlight that Au10In3 possesses intermediate mechanical strength and thermal conductivity within the Au–In system.