Institute of Engineering Innovation, The University of Tokyo, Tokyo, Japan.
Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Kyoto, Japan.
Nat Mater. 2021 Jul;20(7):951-955. doi: 10.1038/s41563-020-00879-z. Epub 2021 Jan 11.
Grain boundary (GB) migration plays an important role in modifying the microstructures and the related properties of polycrystalline materials, and is governed by the atomistic mechanism by which the atoms are displaced from one grain to another. Although such an atomistic mechanism has been intensively investigated, it is still experimentally unclear as to how the GB migration proceeds at the atomic scale. With the aid of high-energy electron-beam irradiation in atomic-resolution scanning transmission electron microscopy, we controllably triggered the GB migration in α-AlO and directly visualized the atomistic GB migration as a stop motion movie. It was revealed that the GB migration proceeds by the cooperative shuffling of atoms on GB ledges along specific routes, passing through several different stable and metastable GB structures with low energies. We demonstrated that GB migration could be facilitated by the GB structural transformations between these low-energy structures.
晶界（GB）迁移在改变多晶材料的微观结构和相关性质方面起着重要作用，并且受原子从一个晶粒迁移到另一个晶粒的原子机制控制。尽管这种原子机制已经得到了深入研究，但在原子尺度上晶界迁移是如何进行的，在实验上仍不清楚。借助原子分辨扫描透射电子显微镜中的高能电子束辐照，我们可以在原子尺度上可控地触发 α-AlO 中的晶界迁移，并直接将原子尺度的晶界迁移可视化作为一个定格电影。结果表明，晶界迁移是通过沿特定路径在晶界梯级上的原子协同交错进行的，在这个过程中经历了几个不同的低能稳定和亚稳态晶界结构。我们证明了晶界迁移可以通过这些低能结构之间的晶界结构转变来促进。
