Abstract In Mg-Gd-Y-Zn-Zr alloy, the ratio of Zn/(Gd+Y) has a significant influence on the structure and distribution of second phases, which further affects the properties of the alloy. Here we regulated the feature of second phases through altering the Zn/(Gd+Y) ratio with 0.14, 0.21 and 0.25, and analyzed the effects of the Zn/(Gd+Y) ratio on microstructure evolution and mechanical properties of these alloys. The extruded alloys all present bimodal structure, which including the fine grain with diameters below 3 μm and coarse grain with diameters more than 3 μm, and the alloy with Zn/(Gd+Y) ratio of 0.21 shows highest area fraction of fine grain. The sample with Zn/(Gd+Y) ratio of 0.25 shows numerous large block-shaped LPSO phases, while the LPSO phases in the alloys with Zn/(Gd+Y) ratio of 0.14 and 0.21 are much finer. For the alloy with Zn/(Gd+Y) ratio of 0.21, lamellar LPSO phases/SFs exist in the matrix, and some atom clusters exist as well. Extruded alloy with Zn/(Gd+Y) ratio of 0.21 possesses excellent ductility as well as a clear yield drop compared with alloys with higher (0.25) or lower (0.14) Zn/(Gd+Y) ratio. The higher area fraction of fine grain and fine LPSO phases ensure excellent ductility, and the significant solute-dislocation interaction is responsible for a clear yield drop.

中文翻译：

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Zn/(Gd+Y)比对Mg-Gd-Y-Zn-Zr合金组织演变和力学性能的影响

摘要 在Mg-Gd-Y-Zn-Zr合金中，Zn/(Gd+Y)比对第二相的结构和分布有显着影响，进而影响合金的性能。在这里，我们通过将 Zn/(Gd+Y) 比改变为 0.14、0.21 和 0.25 来调节第二相的特征，并分析了 Zn/(Gd+Y) 比对这些合金的微观结构演变和机械性能的影响。挤压合金均呈现双峰结构，包括直径小于3 μm的细晶粒和直径大于3 μm的粗晶粒，Zn/(Gd+Y)比为0.21的合金细晶粒面积分数最高。Zn/(Gd+Y) 比为 0.25 的样品显示出许多大块状 LPSO 相，而 Zn/(Gd+Y) 比为 0.14 和 0.21 的合金中的 LPSO 相要细得多。对于Zn/(Gd+Y)比为0.21的合金，基体中存在层状LPSO相/SFs，也存在一些原子簇。与具有较高 (0.25) 或较低 (0.14) Zn/(Gd+Y) 比率的合金相比，Zn/(Gd+Y) 比率为 0.21 的挤压合金具有优异的延展性以及明显的屈服下降。细晶粒和细 LPSO 相的较高面积分数确保了优异的延展性，显着的溶质位错相互作用导致明显的屈服下降。