First-principles calculations of finite-temperature thermodynamic properties of binary solid solutions in the Al-Cu-Mg system

Based on first-principles calculations in terms of the 16-atom special quasirandom structures (SQSs), enthalpy of mixing at 0 K as well as thermodynamic properties, including Gibbs energy of mixing, enthalpy of mixing, and entropy of mixing (ΔG, ΔH, ΔS), have been investigated for the binary solid solutions in the Al-Cu-Mg system. The targeted binary solid solutions include fcc, bcc, hcp phases in the Al-Cu, Al-Mg, and Cu-Mg systems. For the Al-Cu system, the present first-principles predictions are in good agreement with the experimental data and the CALculation of PHAse Diagram (CALPHAD) modeling results. For the Al-Mg and Cu-Mg systems, where the reliable experimental information is not available, it is expected that the presently predicted thermodynamic properties could yield a helpful insight into the phase stabilities in these two systems, in particular for the metastable phases.