Grain growth under shear annealing is crucial for controlling the properties of polycrystalline materials. However, their microscopic kinetics are not well understood because individual atomic trajectories are difficult to track. Here, we study grain growth with single-particle kinetics in colloidal polycrystals using video microscopy. Rich grain-growth phenomena are revealed in three shear regimes, including the normal grain growth (NGG) in weak shear melting–recrystallization process in strong shear. For intermediate shear, early stage NGG is arrested by built-up stress and eventually gives way to dynamic abnormal grain growth (DAGG). We find that DAGG occurs via a melting–recrystallization process, which naturally explains the puzzling stress drop at the onset of DAGG in metals. Moreover, we visualize that grain boundary (GB) migration is coupled with shear via disconnection gliding. The disconnection-gliding dynamics and the collective motions of ambient particles are resolved. We also observed that grain rotation can violate the conventional relation R×θ=constant (R is the grain radius, and θ is the misorientation angle between two grains) by emission and annihilation of dislocations across the grain, resulting in a step-by-step rotation. Besides grain growth, we discover a result in shear-induced melting: The melting volume fraction varies sinusoidally on the angle mismatch between the triangular lattice orientation of the grain and the shear direction. These discoveries hold potential to inform microstructure engineering of polycrystalline materials.

剪切退火下的晶粒生长对于控制多晶材料的性能至关重要。但是，由于很难追踪各个原子的轨迹，因此对它们的微观动力学还不太了解。在这里，我们使用视频显微镜研究胶体多晶体中单颗粒动力学的晶粒长大。在三种剪切状态下都显示出丰富的晶粒长大现象，包括弱剪切熔融-重结晶过程中的正常晶粒生长（NGG）。对于中等剪切，早期的NGG被积聚的应力阻止，最终让位于动态异常晶粒生长（DAGG）。我们发现DAGG是通过熔化-再结晶过程发生的，这自然可以解释在金属中DAGG出现时令人费解的应力下降。此外，我们可以看到，晶界（GB）的迁移是通过断续滑动与剪切作用相结合的。解决了分离滑行动力学和周围粒子的集体运动。我们还观察到谷物旋转会违反常规关系[R×θ=CØñsŤ一种ñŤ（R是晶粒半径，θ是两个晶粒之间的取向差角）是通过发射和an灭整个晶粒上的位错而引起的，从而逐步旋转。除了晶粒长大之外，我们还发现了剪切引起的熔化的结果：熔化体积分数在晶粒的三角形晶格取向与剪切方向之间的角度不匹配上呈正弦变化。这些发现具有为多晶材料的微结构工程提供信息的潜力。