Influence of Gd element content (9, 13 wt%) on the hot deformation behavior and microstructure evolution of Mg-Gd-Y-Zn-Zr alloys

The hot compression tests of Mg-xGd-4Y–2Zn-0.5Zr (x = 9, 13 wt%) were conducted through Gleeble-3800 thermal simulation testing machine with deformation temperature range of 400–490 °C and strain rate from 0.001s −1 to 1s −1 . The effects of Gd element content on the hot deformation behavior, dynamic recrystallization and texture evolution were revealed. The results indicate that increasing Gd content significantly enhances the hot deformation activation energy, with values of 287.17 kJ/mol and 296.78 kJ/mol for the 9Gd and 13Gd alloys, respectively, attributed to intensified dynamic precipitation and Zener pinning effects. Processing maps reveal a narrower stable deformation domain for the 13Gd alloy (450–490 °C/0.01–0.1 s −1 ) compared to the 9Gd alloy (420–450 °C/0.01–0.1 s −1 and 450–490 °C/0.01∼1s −1 ), due to its greater susceptibility to flow instability. Microstructural analyses demonstrate that higher Gd content promotes the formation of dense LPSO phases, which facilitate particle-stimulated nucleation of dynamic recrystallization at elevated temperatures, leading to refined grains and increased high-angle grain boundaries. Additionally, Gd addition effectively weakens the basal texture and promotes a randomized rare-earth texture, improving formability.