Dynamic compression experiments of fine grained Mg–7Gd–5Y–1.2Nd–0.5Zr alloy were measured by the split-Hopkinson pressure bar test at the strain rates in the range 1000–2000 s⁻¹ and the temperature range 293–573 K along the transverse direction. The microstructure of the alloy was characterized by electron back-scattering diffraction and transmission electron microscopy. The results showed that the deformation hardening mechanisms dominated by pyramidal <c + a> slip and assisted by many mechanisms such as tension twinning, while the deformation softening mechanism just dominated by a partial dynamic recrystallization at the grain boundaries. During the entire deformation process at different temperatures, softening was found as the only accompanying mechanism of hardening. Even at 573 K, the fully recrystallized structure was not achieved, and the hardening mechanism was always dominant until they tend to balance. Based on these deformation mechanisms, especially the continuous attenuation mechanism of dynamic recrystallization softening associated with hardening, the Johnson–Cook model was modified, and a unified constitutive equation for deformation under high strain rate at different temperatures was constructed. The resulted obtained by this equation were in good agreement with the experimental results.

细晶粒Mg-7Gd-5Y-1.2Nd-0.5Zr合金的动态压缩实验通过裂口霍普金森压力棒试验在1000-2000 s ^-1范围内的应变速率下进行了测量。沿横向方向的温度范围为293-573K。通过电子反向散射衍射和透射电子显微镜对合金的微观结构进行了表征。结果表明，形变硬化机制主要由锥体<c + a>滑移主导，并由许多机制如张力孪生辅助，而形变软化机制仅由晶界的部分动态再结晶决定。在不同温度下的整个变形过程中，发现软化是硬化的唯一伴随机制。即使在573 K时，也无法实现完全重结晶的结构，并且硬化机制始终占主导地位，直到它们趋于平衡为止。基于这些变形机制，尤其是动态再结晶软化与硬化的连续衰减机理，修改了Johnson-Cook模型，并建立了一个统一的本构方程，用于在不同温度下高应变率下的变形。该方程得到的结果与实验结果吻合良好。