时效强化是稀土镁合金获得高强度的主要因素。为了获得高的时效硬化效果，镁合金的稀土含量较高、时效时间较长，如何降低稀土含量同时保证力学性能成为镁合金研究的热点。本项目拟在低含量稀土镁合金时效过程中添加外应力，通过应力场和温度场的耦合作用精细调控合金的微观组织，优化合金性能。本项目以Mg-3Sm-1.5Gd-0.3Zn-0.5Zr（wt%）合金为研究对象，应用高分辨透射电子显微技术和高角度环形暗场扫描透射技术，结合第一性原理计算研究稀土镁合金在应力时效过程中的析出行为，研究应力的加载方式和大小对稀土镁合金应力时效过程中强化相析出的种类、数量、尺寸、分布、形貌、取向等特征的影响规律。探讨应力诱发析出过程的机理，探明应力时效工艺对稀土镁合金组织和性能的影响规律。通过应力时效处理提高稀土镁合金的综合力学性能同时缩短时效时间，为开发稀土镁合金微观组织调控新技术提供实验依据和理伦指导。

Age hardening is the main factor for obtaining high strength of rare earth magnesium alloy. Generally, in order to obtain a high age hardening effect, the magnesium alloy has a high rare earth content and a long aging time. How to reduce the amount of rare earth and ensure the mechanical properties has become a hot spot in the research of magnesium alloys. This project intends to add external stress during the aging process of the low-content rare earth magnesium alloy, finely regulate the microstructure of the alloy through the coupling of stress field and temperature field to optimize the alloy performance. This project takes Mg-3Sm-1.5Gd-0.3Zn-0.5Zr (wt%) rare earth magnesium alloy as the research object, using high resolution electron microscopy (HRTEM) and high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM), combine with the first principles method to study the precipitation behavior of rare earth magnesium alloy during stress aging, study the effect of stress loading mode and stress magnitude on the type, quantity, size, distribution, morphology and orientation of the strengthening phase of the rare earth magnesium alloy. The mechanism of stress-induced precipitation process was discussed, and the influence of stress aging process conditions on the microstructure and properties of rare earth magnesium alloy was studied. Using stress aging treatment improves the mechanical properties of rare earth magnesium alloys while shortening the aging time, which provides experimental basis and theoretical guidance for the development of new microstructure control technology of rare earth magnesium alloys.