First-principles investigation of the phase stability and early stages of precipitation in Mg-Sn alloys

Recently, remarkable experimental progress has been made toward understanding the metastable phases in Mg-Sn alloys, a promising candidate for rare-earth-free Mg-based alloys. However, the detailed structures and stability of these phases remain unclear. Here, the authors addressed this question comprehensively using a combined approach of density functional theory, cluster expansion, and Monte Carlo calculations. In addition, the preferred atomic-scale ordering at localized regions and its role in the early stages of precipitation are revealed, suggesting a new precipitation sequence in accordance with experiments. This work paves the way for designing precipitation-strengthened rare-earth-free Mg-Sn based alloys.