How to effectively improve the precipitation hardness response of Mg alloys with relatively low RE content is an interesting and important topic. In the present study, an extra stress is added instead of just exposing the sample (extruded Mg–6Gd–1Ca alloy) in high temperature (175 °C) to modify the precipitation behavior and improve the hardness of alloy. Microstructural examinations of the aged alloy by transmission electron microscopy (TEM) show that the weak age-hardening response is mainly attributed to the low number intensity and relatively large size of precipitates in grains. The results suggest that the creep process can effectively promote precipitation response compared with the aging process. TEM analyses indicate a large amount of nano-scale precipitates (espically β' phase) can be formed in grains of the crept alloy, which is mainly responsible for the obvious hardness increase of the alloy after creep. Electron backscattered diffraction (EBSD) data suggest that the dislocation increase caused by strain during creep is responsible for the precipitate increase through providing more nucleation sites.

如何有效改善稀土含量相对较低的镁合金的沉淀硬度响应是一个有趣而重要的课题。在本研究中，添加了额外的应力，而不是仅仅将样品（挤压的Mg-6Gd-1Ca合金）暴露在高温（175°C）下，以改善析出行为并提高合金的硬度。通过透射电子显微镜（TEM）对时效合金的显微组织检查表明，时效硬化反应较弱，主要归因于晶粒中较低的数量强度和相对较大的析出物尺寸。结果表明，与时效过程相比，蠕变过程可以有效地促进降水响应。TEM分析表明，可在蠕变合金的晶粒中形成大量的纳米级沉淀物（尤其是β'相），这是造成合金蠕变后硬度明显增加的主要原因。电子背散射衍射（EBSD）数据表明，蠕变过程中由应变引起的位错增加是通过提供更多的成核位点而导致沉淀物增加的原因。