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.