Atomistic grain boundary migration in Al₂O₃

Abstract

Grain boundary (GB) migration is one of the most important phenomena in materials science, which plays a key role in modifying the microstructures and properties of polycrystalline ceramic materials. Understanding how GB migrates is thus a fundamental and critical issue for future ceramic material design. While the understanding of GB atomic structures has evolved significantly over the past several decades due to the progress of atomic‐resolution electron microscopy and atomistic simulation, the understanding of the atomistic grain boundary migration is still lacking. The present article briefly reviews our recent progress on the direct observation of atomistic GB migration in ceramic material by atomic‐resolution scanning transmission electron microscopy (STEM). Using Al2O3 as a model material, we found that the atomistic GB migration proceeds with atom shuffling accompanied by GB structural change and/or nucleation of disconnection, which is highly dependent on the GB atomic structures.

Molecular Dynamics Study of Temperature Dependence of Grain Boundaries (100) in Pure Aluminum with Application of Machine Learning

“…The practical significance of studying the energy of GBs of different types is justified by the fact that such physical processes as recrystallisation and the evolution of grain structure in polycrystals in the process of annealing or under the action of load depend on the mobility of GBs, which depends on the GB energy. Experimental studies of GB motion in Al 2 O 3 at the atomic level [32] show that the boundary structure changes inhomogeneously during its motion. The authors show that the GB motion gives rise to grain boundary structural units that change depending on the local curvature of the boundary, and these structural units have different energies [22].…”