Hot deformation behavior and microstructure evolution of Mg-Gd-Sm(-Zn)-Zr alloy

The dynamic recrystallization and dynamic precipitation of Mg-5Gd-3Sm(-1Zn)-0.5Zr alloy after hot compression deformation were analyzed by EBSD and TEM techniques. The dynamic recrystallization mechanisms were investigated. Calculated the deformation activation energy, established the constitutive equation, created a critical strain model. The results indicate that the presence of the Zn element enhanced the production of DRX, considerably reduces the strength of {0001} plane texture, and boosts the Schmidt factor of nonbasal plane slip. The Mg-5Gd-3Sm-0.5Zr alloy had a low degree of DRX and it was manifested as a monolayer of DRX grains at the grain boundaries, and was dominated by the DDRX mechanism. The Mg-5Gd-3Sm-1Zn-0.5Zr alloy had a high degree of DRX, which occurred in the form of multilayered DRX grains by the main mechanism of CDRX. Compared with the Mg-5Gd-3Sm-0.5Zr alloy, in addition to the Mg5(Gd, Sm) phase, the Mg-5Gd-3Sm-1Zn-0.5Zr alloy also introduced a new dynamic precipitation phase called (Mg, Zn)3(Gd, Sm) phase. The dynamic precipitation phase prevented grain boundary migration and dislocation motion, which promoted DRX nucleation and prevented the growth of recrystallized grains.