Unveiling the microstructural evolution of an Mg-Gd-Y-Zn-Zr alloy during electrically assisted compression: Deformation mechanisms and dynamic recrystallization

Electrically assisted forming is an advanced plastic forming process that can effectively reduce flow stress and improve formability. In this study, the mechanical response and microstructural evolution of an extruded Mg-8Gd-3Y-0.5Zn-0.5Zr magnesium alloy containing rare earth elements and long period stacking ordered (LPSO) phases during electrically assisted compression (EAC) at equivalent temperatures of 200–450 °C were investigated. The results show that, during EAC, the flow stress of the alloy decreases significantly with increasing equivalent temperature. Microstructural analysis reveals the strong influence of temperature on the dominant deformation mechanisms and dynamic recrystallization behavior. At 250 °C, strain accommodation at the early stage mainly relies on {10−12} extension twinning, resulting in a strong < 0001 > //CD texture. Dynamic recrystallization under this condition is mainly governed by continuous dynamic recrystallization (CDRX). As the temperature increases to 400 °C, twinning is markedly suppressed, 〈c+a〉 dislocation slip is extensively activated, and lamellar LPSO phases undergo kinking to accommodate strain. Under this condition, the discontinuous dynamic recrystallization (DDRX) characteristics of the DRX mechanism become more pronounced. Meanwhile, dynamically precipitated Mg₅RE particles induce PSN, further promoting the randomization of recrystallized grain orientations and thereby significantly weakening the macroscopic compressive texture. This study clarifies the second-phase evolution, dominant deformation mechanisms, and texture evolution characteristics under different current densities, providing experimental evidence and mechanistic guidance for electrically assisted forming and microstructural regulation of rare-earth magnesium alloys.