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-Al₂O₃ 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能方面发挥着重要作用，并且受原子从一个晶粒转移到另一个晶粒的原子机制支配。尽管已经对这种原子机制进行了深入研究，但对于 GB 迁移如何在原子尺度上进行尚不清楚。借助原子分辨率扫描透射电子显微镜中的高能电子束照射，我们可控地触发了 α-Al ₂ O _{3中的 GB 迁移}并将原子 GB 迁移直接可视化为定格动画。研究表明，GB 迁移是通过 GB 壁架上的原子沿特定路线协同改组进行的，通过几种不同的低能量稳定和亚稳态 GB 结构。我们证明了这些低能结构之间的GB结构转变可以促进GB迁移。