Effect of cryogenic rolling process on microstructure and mechanical properties of Mg-14Li-1Al alloy

Mg-14Li-1Al (LA141) alloy was processed by cryogenic rolling (CR) and room temperature rolling (RTR) with large deformation. The microstructure evolution in the CR and RTR-processed samples was investigated. The dynamic recrystallization grains with sub-micron size were observed in both rolled samples. A large number of nano-twins appeared in the CR-processed sample. Compared with the as-homogenized specimen, the mechanical properties of both rolled specimens were significantly improved. The ultimate tensile strength (UTS) of the RTR and CR-processed specimens increased by 36% and 46% respectively, reaching 208 MPa and 223 MPa due to the grain boundary strengthening and dislocation strengthening. The elongation of the RTR-processed specimen increased by nearly three times, 18.5%, mainly due to the formation of dynamic recrystallization grains. And that of the CR-processed specimen increased by more than four times, 25.8%, because of the coordinated deformation of dynamic recrystallization and nano-twins.