Figuring out the effects of LPSO morphology on the deformation mode and strengthening mechanism of Mg-RE alloys is helpful to improve their formability and mechanical properties. In this work, the Mg-8Gd-1Er-1Zn-0.6Zr (GEZ811) alloys with monolithic block LPSO (B-alloy) and lamellar LPSO (L-alloy) phase were respectively prepared by different heat treatment route. The effects of the monolithic LPSO morphology on deformation mode and strengthening mechanisms during high strain rate multidirectional forging (HSMDF) were analyzed. Results showed at the initial stage of HSMDF, twinning was the dominant deformation mode for B-alloy while non-basal slip was for L-alloy. With increasing forging pass, kink band of grains became primary for B-alloy, whereas kinking and breaking of the lamellar LPSO phase was dominant for L-alloy. The optimal UTS, YS and EL of the HSMDFed B-alloy and L-alloy at 12 P were 381.6 MPa, 324.1 MPa, and 8.8 %, and 358.4 MPa, 295.0 MPa, and 5.5 %, respectively. The difference in strength between B-alloy and L-alloy resulted primarily from the contribution of grain boundary strengthening and stacking fault strengthening, while the better plasticity of B-alloy was attributed to its lower deformation activation energy and the formed kink band of grains. Retaining the block LPSO phase as much as possible in the alloy before deformation is beneficial to enhancing the mechanical performance of Mg-RE alloys.

中文翻译：

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不同LPSO形貌Mg-Gd-Er-Zn-Zr合金的变形模式及强化机制

弄清楚LPSO形貌对Mg-RE合金变形模式和强化机制的影响有助于提高其成形性能和力学性能。本文通过不同的热处理途径分别制备了具有整体块状LPSO（B合金）和片状LPSO（L合金）相的Mg-8Gd-1Er-1Zn-0.6Zr（GEZ811）合金。分析了整体 LPSO 形态对高应变率多向锻造 (HSMDF) 过程中变形模式和强化机制的影响。结果表明，在HSMDF的初始阶段，B合金的主要变形模式是孪晶，而L合金的主要变形模式是非基础滑移。随着锻造道次的增加，B 合金中晶粒扭结带成为主要现象，而 L 合金中片状 LPSO 相的扭结和断裂则占主导地位。 HSMDFed B 合金和 L 合金在 12 P 时的最佳 UTS、YS 和 EL 分别为 381.6 MPa、324.1 MPa 和 8.8%，以及 358.4 MPa、295.0 MPa 和 5.5%。 B合金和L合金的强度差异主要归因于晶界强化和堆垛层错强化的贡献，而B合金较好的塑性归因于其较低的变形激活能和形成的晶粒扭结带。变形前合金中尽可能保留块状LPSO相，有利于提高Mg-RE合金的力学性能。