Thermodynamic Reassessment of the Au-In Binary System Supported with First-Principles Calculations

Abstract

The Au-In binary system has been reviewed and the thermodynamic description was re-assessed using the CALPHAD method with aid of first-principles calculations based on density functional theory (DFT). The predicted enthalpy of formation of all stable and hypothesized intermetallics in the Au-In binary system were used to support the optimization. Compared with the previous assessment of this system, a part of thermodynamic models of the intermediate phases were renewed by considering their atomic positions in the lattice, e.g. the model of Au$_3$In$_2$ ($\Psi$) phase was revised as (Au)$_{0.2}$(Au, In)$_{0.6}$(In)$_{0.2}$, Au$_9$In$_4$ ($\gamma$) phase was considered as an intermetallic, modeling as (Au)$_{0.6923}$(In)$_{0.3077}$, and Au$_{10}$In$_3$ ($\beta '$) phase was corrected numerically as (Au)$_{0.769}$(In)$_{0.231}$. The calculated phase diagram agrees well the experimental phase equilibrium data in the literature and the resulting thermodynamic properties are more reasonable. By the coupling of the phase diagram data and experimental together with predicted thermodynamic data, a set of thermodynamic parameters describing all phases in the Au-In system was obtained.