The atomistic mechanism by which grain boundaries migrate was important for understanding the relationship between their structures and dynamic properties. A series of 3-dimensional molecular dynamic simulations of the migration of Σ5 tilt grain boundaries of different inclinations in Ni were performed. The migration mechanism was identified by frequent quenches, and analysis of the atomic displacements, local and global excess volume and stress. The migration mechanism had various components: local volume fluctuations preceded displacements of 3 to 4 linear atomic clusters in a direction parallel to the tilt axis. These, in turn, were followed by individual atomic hopping that were mainly perpendicular to the boundary plane. The excess volume was the key to volume fluctuations and to atomic hopping perpendicular to the boundary plane. Linear, or string-like, atomic motion parallel to the tilt axis also gave rise to a strong anisotropy in grain-boundary self-diffusivity.

Simulation and Analysis of the Migration Mechanism of Σ5 Tilt Grain Boundaries in an FCC Metal. H.Zhang, D.J.Srolovitz: Acta Materialia, 2006, 54[3], 623-33