Xie Hongbo, Huang Qiuyan, Bai Junyuan, Li Shanshan, Liu Yang, Feng Jianguang, Yang Yuansheng, Pan Hucheng, Li Hongxiao, Ren Yuping, Qin Gaowu
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
Nano Lett. 2021 Apr 14;21(7):2870-2875. doi: 10.1021/acs.nanolett.0c05008. Epub 2021 Mar 23.
Interfacial segregation is ubiquitous in mulit-component polycrystalline materials and plays a decisive role in material properties. So far, the discovered solute segregation patterns at special high-symmetry interfaces are usually located at the boundary lines or are distributed symmetrically at the boundaries. Here, in a model Mg-Nd-Mn alloy, we confirm that elastic strain minimization facilitated nonsymmetrical segregation of solutes in four types of linear tilt grain boundaries (TGBs) to generate ordered interfacial superstructures. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy observations indicate that the solutes selectively segregate at substitutional sites at the linear TGBs separated by periodic misfit dislocations to form such two-dimensional planar structures. These findings are totally different from the classical McLean-type segregation which has assumed the monolayer or submonolayer coverage of a grain boundary and refresh understanding on strain-driven interface segregation behaviors.
界面偏析在多组分多晶材料中普遍存在，并且在材料性能中起着决定性作用。到目前为止，在特殊高对称界面处发现的溶质偏析模式通常位于边界线上或在边界处对称分布。在此，在一种Mg-Nd-Mn模型合金中，我们证实弹性应变最小化促进了溶质在四种类型的线性倾斜晶界（TGB）中非对称偏析，从而产生有序的界面超结构。像差校正高角度环形暗场扫描透射电子显微镜观察表明，溶质选择性地偏析在由周期性失配位错分隔的线性TGB处的替代位点上，以形成这种二维平面结构。这些发现与假设晶界为单层或亚单层覆盖的经典麦克林型偏析完全不同，并刷新了对应变驱动界面偏析行为的认识。
