The effect of rotational-die equal channel angular pressing (RD-ECAP) temperature and deformation route on the microstructure and mechanical properties of pre-extruded Mg-5Gd-3Y-1Zn-0.5Zr (wt%) alloys were investigated. The results indicate that the RD-ECAP updates both the α-Mg texture and long-period stacking ordered (LPSO) arrangement in the pre-extruded alloy, while the α-Mg texture is more sensitive to the change of deformation route. The LPSO streamlines modify the anisotropy of mechanical properties of the ECAP alloys via exerting different reinforcing effects and modifying the crack propagation. The lower ECAP temperature of 350 °C rather than 400 °C promotes dynamic precipitation which deteriorates the following ageing-hardening response but conduces to refining the α-Mg grains and preventing a sharp drop in elongation after peak ageing. The 350A peak-aged alloy exhibits the optimal mechanical properties with the average tensile yield strength (TYS) of 311 MPa ( = 3.7, indicates standard deviation) and elongation of 7.6 % ( = 0.7). Its higher strength should mainly be attributed to the finer grain size, and its quasi-isotropic performance should be inherited from the ECAP state induced by the rational arrangement of LPSO phases.

中文翻译：

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ECAP温度和变形路径对预挤压Mg-5Gd-3Y-1Zn-0.5Zr合金力学性能的影响


研究了旋转模等通道角挤压（RD-ECAP）温度和变形路径对预挤压Mg-5Gd-3Y-1Zn-0.5Zr（wt%）合金显微组织和力学性能的影响。结果表明，RD-ECAP同时更新了预挤压合金中的α-Mg织构和长周期堆叠有序（LPSO）排列，而α-Mg织构对变形路径的​​变化更敏感。 LPSO流线通过发挥不同的强化效应和改变裂纹扩展来改变ECAP合金机械性能的各向异性。 350 °C（而非 400 °C）的较低 ECAP 温度会促进动态析出，从而恶化随后的时效硬化响应，但有助于细化 α-Mg 晶粒并防止峰值时效后伸长率急剧下降。 350A 峰值时效合金表现出最佳的机械性能，平均拉伸屈服强度 (TYS) 为 311 MPa（= 3.7，表示标准差），伸长率为 7.6%（= 0.7）。其较高的强度主要归因于更细的晶粒尺寸，其准各向同性性能应继承自LPSO相合理排列引起的ECAP状态。