This study is focused on high strain rate superplasticity of commercial magnesium alloy Mg–4Y-3RE (WE43) in ultrafine-grained condition prepared by equal channel angular pressing (ECAP). Attaining microstructure with the average grain size of ∼340 nm and high density of secondary phase particles provided a possibility to significantly decrease temperature during the deformation at strain rate 10⁻² s⁻¹ and 10⁻¹ s⁻¹ in comparison with previous studies. Consequently, extent of negative effect of grain growth was partially suppressed and the investigated alloy did exhibit exceptionally high deformability with a maximum elongation of ∼1230% at strain rate 10⁻² s⁻¹ and at two temperatures: 350 °C and 400 °C. Increase in the strain rate to 10⁻¹ s⁻¹ resulted in maximum elongation of ∼1000% at the temperature of 400 °C. The microstructural analysis after the deformation showed that the microstructure was fine-grained even after large deformation and plasticity-controlled growth of cavities did occur only at a temperature of 450 °C. The optimization of ECAP processing resulted in very weak texture and, therefore, the deformability should be more isotropic in comparison with strongly textured materials usually investigated in this regard.

这项研究的重点是通过等通道角向压制（ECAP）在超细晶粒条件下商业镁合金Mg–4Y-3RE（WE43）的高应变速率超塑性。与先前的研究相比，获得具有约340 nm的平均晶粒尺寸和高密度的第二相颗粒的显微组织，提供了在应变速率10 ^-2 s ^-1和10 ^-1 s ^-1变形期间显着降低温度的可能性。因此，晶粒生长的负面影响程度得到部分抑制，并且所研究的合金确实表现出异常高的变形性，在应变率10 ^-2 s ^-1时最大伸长率约为1230％以及两个温度：350°C和400°C。应变速率增加到10 ^-1 s ^-1导致在400°C的温度下最大伸长率约为1000 ％。变形后的显微组织分析表明，即使在大变形之后，显微组织仍是细晶粒的，并且仅在450°C的温度下才发生了可塑性控制的空洞生长。ECAP工艺的优化导致非常弱的质地，因此，与通常在这方面进行研究的强烈质地的材料相比，变形能力应更具各向同性。