Microstructure and texture evolution for dynamic plastic deformed pure magnesium during isothermal annealing

Abstract

Microstructure and texture evolution during isothermal annealing at 473K, 513K and 553K with various holding times for pure magnesium deformed at a strain rate of 102s−1 to a strain of −0.08 were studied in the present work. High strain rate deformation provides a higher driving force for subsequent recrystallization than a low strain rate. Static recrystallization (SRX) grains and grain growth associated with the vanishing of low angle and twin boundaries were observed during the annealing process. SRX grains were detected adjacent to {101¯1}−{101¯2} double twin as well as original grain boundaries. It indicates that both double twin and original grain boundaries are the sites favored for SRX nucleation, attributing to the relatively high stored energy accumulated by dislocations during dynamic plastic deformation (DPD). Grain growth rate increases with temperature and the highest rates occur at the period of 900–1800s for annealing at 513K and 553K, but retains a relatively low value at 473K. The intensity of macro-texture increases at the beginning of annealing due to the similar orientation between recrystallized grains and the parent matrix, whereas it decreases with further annealing for the migration of grain boundaries during grain growth. The evidence of Schmid factor (SF) value evolution shows that the annealed microstructure is more favorable for basal glide than the deformed condition.