Investigation on deformation mechanism and recrystallization behavior of a Mg–Gd–Y–Zn–Mn alloy by hot compression

Abstract

This study investigates the hot deformation behavior of a Mg–Gd–Y–Zn–Mn alloy. A strain-compensated hyperbolic-sine Arrhenius constitutive model was established, and hot processing maps were constructed. The dynamic recrystallization (DRX) mechanisms and the roles of second phases under different deformation conditions were systematically examined. The results show that the constitutive model exhibits reasonable fitting accuracy (correlation coefficient R = 0.992, root mean square error RMSE = 8.992MPa, and average absolute relative error AARE = 7.283%). The hot processing maps indicate that the optimum hot working window is 420–500 °C with a strain rate of approximately 0.01 s⁻¹. Microstructural analysis reveals that in the instability region, deformation is dominated by prismatic <a> slip, the DRX fraction is below 10%, and discontinuous DRX (DDRX) is the primary mechanism, while continuous DRX (CDRX) is suppressed by lamellar LPSO phases. In the instability-edge region, prismatic <a> slip remains dominant but is accompanied by limited basal and pyramidal slip and DDRX still dominates. In the stable region, multiple slip systems are activated simultaneously, and distinct Orowan looping is observed. At high temperatures, most lamellar long-period stacking-ordered (LPSO) phases dissolve, while the undissolved LPSO phases together with α–Mn particles inhibit grain boundary migration, resulting in a bimodal grain structure. This work provides a theoretical basis for designing hot working processes for Mg–Gd–Y–Zn–Mn alloys.