DFT Study of AuIn and AuIn Intermetallic Compounds: Structural Stability, Fracture Toughness, Anisotropic Elasticity, and Thermophysical Properties for Advanced Applications.

This study systematically explores the structural stability, mechanical properties, elastic anisotropy, fracture toughness, and thermophysical characteristics of AuIn and AuIn intermetallic compounds (IMCs) through density functional theory (DFT) simulations. Employing the generalized gradient approximation (GGA) and the Voigt-Reuss-Hill approximation enables precise predictions of polycrystalline elastic behavior, providing critical insights into the intrinsic stability and mechanical anisotropy of these IMCs. Structural optimization identifies the equilibrium lattice parameters and cohesive energies, indicating stronger atomic bonding and superior structural stability in AuIn relative to AuIn. Elastic constant calculations confirm mechanical stability and reveal pronounced anisotropic elastic behavior; AuIn exhibits significant stiffness along the [010] crystallographic direction, while AuIn demonstrates notable stiffness predominantly along the [001] direction. Both AuIn and AuIn exhibit ductile characteristics, confirmed by positive Cauchy pressures and elevated bulk-to-shear modulus (/) ratios. Fracture toughness analysis further establishes that AuIn offers greater resistance to crack propagation compared to AuIn, suggesting its suitability in mechanically demanding applications. Thermophysical property evaluations demonstrate that AuIn possesses higher thermal conductivity, elevated Debye temperature, and superior volumetric heat capacity relative to AuIn, reflecting its enhanced capability for effective thermal management in electronic packaging. Anisotropy assessments, utilizing both universal and Zener anisotropy indices, reveal significantly higher mechanical anisotropy in AuIn, influencing its practical applicability.