Ultrafine-grained Mg-Zn-Zr alloy with high strength and high-strain-rate superplasticity

► An ultrafine-grained ZK60 alloy could be produced by HRDSR. ► The processed ZK60 yielded high strength and high strain rate superplasticity. ► The high strength was attributed to grain-size and precipitation strengthening. ► Thermally stable microstructure was important in the enhanced superplasticity.