In this work, the effects of Zn content (0–2 wt%) on microstructural evolution and mechanical properties of cast Mg–10Gd–3.5Er–0.5Zr alloys are studied. The results show that the as-cast Mg–10Gd–3.5Er–xZn–0.5Zr alloys are mainly composed of Mg matrix and secondary (Mg, Zn)₃(Gd, Er) phases distributed along grain boundaries. With the increase in Zn content, the volume fraction of secondary (Mg, Zn)₃(Gd, Er) phases increases and the grains get refined. In the process of solid solution treatment, Zn addition can lead to the formation of long-period stacking ordered (LPSO) structures and the volume fraction of LPSO structures increases with Zn content. In addition, the Zn addition can reduce the vacancy formation energy and accelerate the diffusion rate of RE elements in Mg matrix. Because of the comprehensive effect of secondary phases and the accelerated diffusion rate, the base alloy and 2Zn alloy have less grain growth after solid solution treatment than that of the 0.5Zn alloy and 1Zn alloy. The precipitation process is also accelerated by enhanced diffusion rate. At room temperature (RT), the strengthening effect of βʹ + β₁ precipitates is more effective than that of LPSO structures, so the peak-aged 0.5Zn alloy exhibits the most excellent mechanical performance at RT, with yield strength of 219 MPa, ultimate tensile strength 296 MPa and elongation of 6.4%. While LPSO structures have stronger strengthening effect at elevated temperature than that of βʹ + β₁ precipitates, so the 1Zn alloy and 2Zn alloy have more stable mechanical performance than that of the base alloy and 0.5Zn alloy with the increase in tensile temperature.

在这项工作中，研究了锌含量（0–2 wt％）对铸造Mg-10Gd-3.5Er-0.5Zr合金的组织演变和力学性能的影响。结果表明，铸态的Mg-10Gd-3.5Er- x Zn-0.5Zr合金主要由Mg基体和沿晶界分布的次生（Mg，Zn）₃（Gd，Er）相组成。随着锌含量的增加，次生（Mg，Zn）₃的体积分数（Gd，Er）相增加，晶粒细化。在固溶处理过程中，锌的添加可导致形成长周期堆积有序（LPSO）结构，且LPSO结构的体积分数随锌含量的增加而增加。另外，Zn的添加可以减少空位形成能并加速RE元素在Mg基体中的扩散速率。由于二次相的综合作用和扩散速度的加快，基体合金和2Zn合金固溶处理后的晶粒生长比0.5Zn合金和1Zn合金小。增加的扩散速率也加速了沉淀过程。在室温（RT），的强化效果β '+  β ₁析出物比LPSO结构更有效，因此峰值时效的0.5Zn合金在室温下表现出最优异的机械性能，屈服强度为219 MPa，极限抗拉强度为296 MPa，伸长率为6.4％。虽然LPSO结构具有在升高的温度下强于强化效果β +'  β _1级的析出物，所以1Zn合金和合金2ZN具有比基体合金和0.5Zn合金与拉伸温度的增加更稳定的机械性能。