First principles study of the elastic and thermodynamic properties of Mg-Al alloys

Abstract Magnesium-aluminium (Mg-Al) alloys with different mass ratios and crystal structures can exhibit different physicochemical properties. The stable/metastable crystal structures of MgxAly (y/(x + y) = 1/16 ~ 15/16) were investigated using the CALYPSO (Crystal structure Analysis by Particle Swarm Optimization) method in combination with ab initio calculations. Mg15Al, Mg3Al and MgAl were determined to be the most stable structures by comparing formation energies with other studies. We calculated their elastic constants, moduli, anisotropy, hardness and thermodynamic properties. Our results demonstrate that all these structures exhibit ductility and anisotropy, and Mg15Al has the greatest hardness.