Zhang Hui, Yu Yue, Dai Xinyue, Yu Jinshan, Xu Hua, Wang Shanshan, Ding Feng, Zhang Jin
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, 410000, P. R. China.
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China.
Small. 2021 Dec;17(51):e2102739. doi: 10.1002/smll.202102739. Epub 2021 Oct 13.
Grain boundaries (GBs) play a central role in the fracture of polycrystals. However, the complexity of GBs and the difficulty in monitoring the atomic structure evolution during fracture greatly limit the understanding of the GB mechanics. Here, in situ aberration-corrected scanning transmission electron microscopy and density functional theory calculations are combined to investigate the fracture mechanics in low-symmetry, polycrystalline, 2D rhenium disulfide (ReS ), unveiling the distinctive crack behaviors at different GBs with atomic resolution. Brittle intergranular fracture prefers to rip through the GBs that are parallel to the Re chains of at least one side of the GBs. In contrast, those GBs, which do not align with Re chains on either side of the GBs, are highly resistant to fracture, impeding or deflecting the crack propagation. These results disclose the GB type-dependent mechanical failure of anisotropic 2D polycrystals, providing new ideas for material reinforcement and controllable cutting via GB engineering.
晶界（GBs）在多晶体断裂中起着核心作用。然而，晶界的复杂性以及在断裂过程中监测原子结构演变的困难极大地限制了对晶界力学的理解。在此，结合原位像差校正扫描透射电子显微镜和密度泛函理论计算，研究低对称、多晶二维二硫化铼（ReS₂）中的断裂力学，以原子分辨率揭示不同晶界处独特的裂纹行为。脆性沿晶断裂更倾向于穿过与晶界至少一侧的Re链平行的晶界。相比之下，那些在晶界两侧都不与Re链对齐的晶界对断裂具有高度抗性，会阻碍或使裂纹扩展发生偏转。这些结果揭示了各向异性二维多晶体中晶界类型依赖的机械失效，为通过晶界工程进行材料强化和可控切割提供了新思路。
