High strength BCC magnesium-Lithium alloy processed by cryogenic rolling and room temperature rolling and its strengthening mechanisms

Based on high Li content, optimizing the mechanical properties of Mg-Li alloy can bring about the good com-bination of ultra-low density and high strength, causing high specific strength. Reducing the deformation tem-perature can effectively maintain the strength improvement of deformed beta-based Mg-Li alloy. In this work, the microstructures and mechanical properties of room-rolled (RR) and cryogenic-rolled (CR) Mg-16Li-4Zn-1Er (LZE1641) alloy were investigated. Results show that cryogenic temperature delays the dynamic recovery (DRV) and dynamic recrystallization(DRX). A tensile strength of 267 MPa can be obtained at CR60%, which is attributed to the nanocrystalline grains and the significantly higher dislocation density than that of the RR alloy. Further CR with 80% reduction makes the form of some alloying elements transform from solid state to pre-cipitation phases, causing relatively decreased strength