The dynamic compression behavior and microstructure evolution at 400 °C of an extruded Mg–8Gd–4Y–Nd–Zr alloy with different tempers were investigated. The peak-aged samples exhibit the highest compressive strength, followed by as-extruded samples and over-aged samples. The highest dynamic compressive strength of 582 MPa was achieved by peak-aged sample compressed at 1224 s⁻¹. The high strength was attributed to the formation of abundant thermally stable βʹ precipitates and some dynamic precipitates. The dynamic compressive strength of peak-aged sample and over-aged sample is not sensitive to strain rates, while that of the as-extruded sample is sensitive to strain rates. The dynamic compressive strength of the as-extruded alloy can reach 535 MPa when compressed at 2024 s⁻¹. The high strength was mainly ascribed to the formation of numerous dynamic precipitates and the work hardening effect caused by dislocations. The cracks are composed of crack that is 45° to loading direction on the cylindrical surface and crack on the compressed surface. Microstructure observation indicates that the crack was easily propagated along the interface between the adiabatic shear band and matrix, grain boundaries. The equilibrium phase β in over-aged sample was unable to hinder the crack propagation.

中文翻译：

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Mg-Gd基合金在高温下的动态压缩行为

研究了不同回火态的Mg-8Gd-4Y-Nd-Zr挤压合金在400°C时的动态压缩行为和微观组织演变。峰值时效样品表现出最高的抗压强度，其次是挤压成型的样品和过时效的样品。通过在1224 s ^-1下压缩的峰值时效样品，获得了582 MPa的最高动态抗压强度。高强度归因于大量的热稳定的β1沉淀物和一些动态沉淀物的形成。峰值时效样品和过时效样品的动态抗压强度对应变速率不敏感，而刚挤出的样品的动态抗压强度对应变速率敏感。挤压后的合金在2024 s ^-1压缩时的动态抗压强度可以达到535 MPa。高强度主要归因于大量动态沉淀的形成和位错引起的加工硬化作用。裂纹由圆柱表面上与加载方向成45度角的裂纹和压缩表面上的裂纹组成。显微组织观察表明，裂纹很容易沿着绝热剪切带与基体，晶界之间的界面扩展。过时效样品中的平衡相β无法阻止裂纹扩展。