Thermodynamic stability of Mg–Y–Zn long-period stacking ordered structures

Although long-period stacking ordered (LPSO) structures have been known to improve mechanical strength in Mg alloys for over a decade, only recently have LPSO crystal structure models been proposed. Using density functional theory (DFT), we explore the thermodynamic stability of two such models with Mg–Y–Zn LPSO structures of 18R and 14H types. All LPSO structures are predicted to be metastable when compared to the 0 K ground state phase diagram, which we construct from DFT calculations of 13 Mg–Y–Zn intermetallic compounds.