Deformation and microstructure evolution of a high strain rate superplastic Mg–Li–Zn alloy

An Mg–8Li–2Zn alloy plate was prepared through a two-pass extrusion process, and the high-temperature behavior of the alloy was investigated at 473–593 K under the initial strain rate of 1.0 × 10−2–1.0 × 10−1 s−1. The results indicated that the alloy exhibits a significant high strain rate superplasticity with a maximum elongation of 279% under an initial strain rate of 1.0 × 10−2 s−1. The activation energy is 89.4 kJ/mol, indicating that the dominant deformation mechanism in the alloy is grain-boundary sliding controlled by grain-boundary diffusion. Cavities nucleate and coalesce during deformation, which is one of the results leading to the fracture of the material.

► High strain rate superplastic in Mg–Li alloy. ► Measurement of the activation energy and superplastic deformation mechanism of the alloy. ► Microstructure evolution, the cavitation development during the tensile testing.