Study of dynamic recrystallization behavior by regulating morphology of LPSO phases in Mg-6Gd-3Y-1.5Zn-0.6Zr alloy

Long-period stacking ordered (LPSO) phases with different morphologies exhibit different deformation behaviors and have different influences on the microstructure evolution of Mg alloy during hot deformation. To investigate the effects of LPSO phases with different morphologies on microstructure and texture, block-shaped and lamellar LPSO phases were obtained by adjusting heat treatment parameters. Hot compression tests were conducted at temperatures ranging from 350 °C to 500 °C and strain rates of 0.001 s -1 ∼1 s -1 . The dynamic recrystallization (DRX) mechanisms of the alloy with block-shaped LPSO phases include continuous dynamic recrystallization (CDRX) and particle-stimulated nucleation (PSN). In contrast, the alloy with lamellar LPSO phases includes CDRX and kinking-assisted DRX. At low temperatures and high strain rates, the block-shaped LPSO phases promoted DRX more efficiently through the PSN mechanism, and the PSN-induced DRX grains effectively reduced the texture intensity. However, more pronounced kinking of the lamellar LPSO phase occurred in the alloy with lamellar LPSO phases at low temperatures and high strain rates. Kinking can weaken the texture, and DRX grains tend to nucleate at the kinking sites. Furthermore, the { } tensile twins were activated to accommodate the deformation due to the absence of kinking behavior of lamellar LPSO phases. Research reveals that the morphology of LPSO phases regulates the DRX nucleation, kinking, and twinning behaviors of Mg-Gd-Y-Zn-Zr alloy during hot compression, which further affects the texture evolution and activation of the slip system.