Strong strain hardening ability in an as-cast Mg-3Al-3Sn alloy

► As-cast Mg-3Al-3Sn alloy shows strong strain hardening ability at room temperature. ► Decrease in generalized stacking fault energies plays an important role in the strain hardening of Mg-3Al-3Sn alloy. ► Increase of dislocation densities show the activation of basal , non-basal and slip. ► TEM photographs show the activation of {101¯2} and {101¯1}−{101¯2} twins.