Effect of pre-deformation on aging characteristics and mechanical properties of a Mg–Gd–Nd–Zr alloy

The effect of plastic deformation prior to artificial aging on the aging characteristics and mechanical properties of a Mg–11Gd–2Nd–0.5Zr (wt.%) alloy was investigated. Induced pre-deformation ranged from 0% to 10% stretch, with an intermediate of 5% stretch. The as-stretched specimens processed high density of dislocations and twins, which increased with elevated deformation level. As compared to non-stretched alloy, the stretched alloy showed accelerated aging kinetics when aged at 200 °C. Comparison of microstructure in non-stretched and stretched specimens after 200 °C/24 h aging showed that pre-deformation contained not only homogeneous precipitates in the matrix but also heterogeneous precipitates at dislocations and twin boundaries. Tensile test results showed that pre-deformation enhanced the strength of the alloy but declined the ductility at temperature below 250 °C. The gain in strength for stretched and aged alloy was attributed to the strengthening of dislocation substructures and twin boundaries together with heterogeneous precipitates.