Strain-rate sensitivity of die-cast magnesium-aluminium based alloys

The strain-rate effect in die-cast magnesium-aluminium based alloys under quasi-static strain rates ranging from 10-6 to 10-1 s-1 was investigated. The strain-rate sensitivity was shown to decrease with increasing aluminium solute level in the matrix. Microstructural examination by electron backscattered diffraction (EBSD) revealed that deformation twinning is more active in the alloys with lower strain-rate sensitivity. It is suggested that the decrease in strain-rate sensitivity with increasing aluminium solute level is likely due to dynamic strain ageing from the interaction between aluminium solute and dislocations. The correlation between strain-rate sensitivity and ductility in AE44 is briefly discussed.