In this work, the in-situ observation of the microstructure in the Mg-2Gd (wt%) alloys during V-bending tests was operated. The microstructure and texture evolutions were characterized by the in-situ electron backscatter diffraction (EBSD), scanning electron microscopy (SEM) and the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) technique. The results revealed a unique microcracks nucleation mechanism in the Mg-Gd alloys compared with the traditional Mg alloy (AZ31 alloy). The microcrack was nucleated at the grain boundary for the Mg-2Gd alloy and in the intragranular for the AZ31 alloy during the bending process. This difference mode between the Mg-Gd and the AZ31 alloys was mainly attributed to the more random topology of the grain boundary network, the lower grain boundary cohesion and the enhanced hinder ability for the dislocations due to the segregated Gd atoms in the Mg-Gd alloy. Furthermore, the microcracks that had a large angle $\theta$ with the extruded direction (ED) in the Mg-Gd alloys were preferred nucleated since grain boundaries had the larger normal stress during the bending process.

在这项工作中，在 V 型弯曲试验期间对 Mg-2Gd (wt%) 合金中的微观结构进行了原位观察。微观结构和织构演变由原位表征电子背散射衍射（EBSD）、扫描电子显微镜（SEM）和高角度环形暗场扫描透射电子显微镜（HAADF-STEM）技术。结果表明，与传统镁合金（AZ31 合金）相比，Mg-Gd 合金具有独特的微裂纹形核机制。在弯曲过程中，微裂纹在 Mg-2Gd 合金的晶界和 AZ31 合金的晶内成核。Mg-Gd 和 AZ31 合金之间的这种差异模式主要归因于晶界网络的更随机的拓扑结构、较低的晶界凝聚力以及由于 Mg-Gd 中的偏析 Gd 原子对位错的阻碍能力增强合金。此外，具有大角度的微裂纹$\theta$由于在弯曲过程中晶界具有较大的法向应力，因此 Mg-Gd 合金中的挤压方向 (ED) 是首选形核的。