Activation of non-basal <c + a> slip in multicomponent Mg alloys

Activating non-basal slip is a key method to improve room temperature ductility and formability of Mg alloys. However, the detailed criterion for activation of the slip in multicomponent Mg alloys, which can be utilized in commercial Mg alloys, requires further understanding. The present authors investigated the mechanism and criterion using a molecular statics simulation on dislocation behaviors in multicomponent Mg alloys. We found that if multicomponent Mg alloys have an equivalent dislocation binding intensity to associated binary Mg alloys that are optimized to minimize the critical resolved shear stress anisotropy and thus activate the slip, then the critical resolved shear stress anisotropy between slip systems of the multicomponent Mg alloys can also be minimized, resulting in activation of the slip. The activation is maximized in multicomponent Mg alloys when alloying a large amount of weak dislocation binding elements. It was confirmed through experiments that the multicomponent Mg alloys satisfying the above criterion show higher room-temperature tensile elongation and formability than other alloys.