High-strain-rate superplasticity of fine-grained Mg-6Zn-0.5Zr alloy subjected to low-temperature indirect extrusion

A commercial Mg-6Zn-0.5Zr alloy was subjected to low-temperature indirect extrusion for grain refinement and the tensile properties of the extruded alloy at 250 degrees C were investigated. After extrusion, the alloy showed finely recrystallized grains with an average size of 1.6 mu m. High-strain-rate superplasticity was observed in the fine-grained alloy, which exhibited a tensile elongation of up to 800% at a strain rate of 0.01 s(-1). Experimental results demonstrating the occurrence of grain boundary sliding during the high-strain-rate superplastic deformation are presented. (C) 2017 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.