Microstructure and mechanical property control of a Mg-Gd-Y-Nd-Zr alloy via extrusion: insights from isothermal compression analysis

Abstract

Based on isothermal compression as the theoretical foundation, this study systematically investigates the dynamic recrystallization (DRX) behavior and texture evolution of Mg-8Gd-4Y-1Nd-0.5Zr alloy under varying temperatures and strain rates. Furthermore, extrusion experiments were conducted to validate the effectiveness of the theoretical guidance derived from isothermal compression. The results of isothermal compression reveal that discontinuous DRX predominates under low-temperature and high-strain-rate conditions, whereas continuous DRX mechanisms accompany the process under high-temperature and low-strain-rate conditions. At 400 °C, dynamic precipitation occurs, which induces particle-stimulated nucleation and promotes grain refinement. As the degree of recrystallization increases, the texture transitions from a strong texture to a more dispersed one. Guided by the isothermal compression qualitative model, extrusion experiments were performed at 400 °C, 450 °C, and 500 °C. The results demonstrate that the alloy extruded at lower temperatures exhibits higher strength due to dynamic precipitation and grain refinement, while the alloy extruded at higher temperatures shows significantly enhanced plasticity attributed to texture randomization. This study verifies the guiding role of isothermal compression qualitative model in the large plastic deformation processing of magnesium alloys and provides both theoretical and experimental foundations for optimizing their hot-working processes.