Realization of high-strain-rate superplasticity at low temperatures in a Mg–Zn–Zr alloy

Possibility of combination of high-strain-rate superplasticity and low-temperature superplasticity was experimentally confirmed using extremely fine-grained magnesium alloy. In order to achieve such a superior superplastic behavior, the required grain size and the suitable processing was considered. It was suggested that the required grain size of ≤≈0.4 μm can be obtained through the processing from powder metallurgy route, using rapidly solidified powder. Therefore, superplastic behavior was examined using powder metallurgy processed Mg–Zn–Zr alloy (ZK61). Tensile tests revealed that high-strain-rate superplasticity was obtained even at low temperatures of ≈473 K, which is corresponding to half the absolute melting point of the material. This was attributed to the fine grain size of 0.65 μm.