Dynamic recrystallization and texture evolution of Mg-6.8Y-2.5Zn-0.3Zr alloy during hot rolling

Abstract

The dynamic recrystallization and changes in the preferred orientation of crystallites during hot rolling at 500 °C have been studied on a cast Mg-6.8Y-2.5Zn-0.3Zr (wt. %) alloy (WZ73) containing long-period stacking ordered (LPSO) phases. The recrystallization began predominantly within twins and also occurred near the LPSO phases. The twinned regions have a much higher stored strain energy compared to the matrix, and are therefore favorable nucleation sites for dynamic recrystallization. Besides, the bits of the LPSO phase located at the grain boundaries of the magnesium matrix grains act as nucleation sites for dynamic recrystallization. With increasing strain from 36 % to 74 %, the average volume fraction of recrystallized grains increased from 3.5 % to 48.8 %. The intensive recrystallization process resulted in basal texture weakening. Thus, the resulting microstructure is a mixture of randomly oriented, dynamically recrystallized and coarse, highly oriented non-recrystallized grains.