Rolling strain rate-driven deformation mechanism transition and mechanical properties enhancement in Mg–10Gd–3Y–0.5Zr alloy

Abstract

This work investigated the effects of rolling strain rates on the deformation mechanisms, microstructure, and mechanical properties of Mg–10Gd–3Y–0.5Zr alloys. As the strain rate increases, the dominant deformation mechanism during the rolling process transitions from a combination of twinning and dislocation slip to a multi-slip mechanism. Correspondingly, the microstructure of low strain rate rolling (LSRR)-treated sample is mainly composed of numerous {10$\overline{1}$2} extension twins and deformed grains. In contrast, twins disappear in the middle (MSRR) and high strain rate rolling (HSRR)-treated samples, and the dynamic recrystallization (DRX) fraction increases with the increasing strain rate, resulting in significant decrease in average grain size. The dominant DRX mechanism also transitions from discontinuous dynamic recrystallization (DDRX) in the MSRR-treated sample to continuous dynamic recrystallization (CDRX) in the HSRR-treated sample. In addition, the basal texture intensity shows an overall decreasing trend with increasing strain rate, while the orientation changes from <10$\overline{1}$0> − <11$\overline{2}$0>//Rolling direction (RD) to <10$\overline{1}$0>//RD. The mechanical properties of the rolled samples monotonically improve with increasing strain rate, specifically, the HSRR-treated sample exhibits enhancements of 44 MPa in yield strength (YS), 96 MPa in ultimate tensile strength (UTS), and 2.9% in fracture elongation (FE) compared to the LSRR sample.