Effect of 6.25 at% Al addition on structural stability of magnesium under high pressure: A first-principles study

The structural stability of pure Mg and Mg–6.25 at% Al under hydrostatic pressures at zero temperature was investigated by employing first-principles total energy calculations. The results show that the adding Al leads to higher enthalpy of forming for all structures of Mg with the increase in the enthalpy for the bcc structure being the highest. The structural stability order does not get affected by the application of hydrostatic pressure. However, compared with pure magnesium, the magnesium with added 6.25 at% Al shows higher hcp → bcc phase transformation pressure point, but lower hcp → fcc pressure point.

Research highlights▶ In this paper, the structural stability for the hcp, bcc and fcc structures of magnesium with added 6.25 at% Al (chemical component similar to a typical Mg–Al system alloy – AZ71) and pure magnesium under hydrostatic pressures are studied by first-principles total energy calculations, respectively. The present work can be expected beneficial to the further improvement of mechanical property for the most widely used magnesium alloy – Mg–Al series alloy.