Microstructure evolution of AZ91D magnesium alloy during high temperature compression

High temperature compression tests of AZ91D magnesium alloy were performed on Gleeble-1500 thermal mechanical simulator at strain rate of 0.01 s-1 and temperature of 400°C. The microstructure evolution of the alloy during compression was examined by optical microscope (OM) and transmission electron microscope (TEM). The results show that {101¯2} twin is primary deformation mechanism and the size of twins is larger at the initial stage of compressive deformation, however, these larger twins will be fragmented and become small under large deformation. With the increasing of strain, some twins cross each other and dynamic recrystallization (DRX) grains are nucleated at twin boundaries and twin intersections.