Mechanisms of Grain-Boundary Diffusion in Two-Dimensional Metals

The mechanisms of diffusion via grain boundaries in two-dimensional metals have been studied by method of molecular dynamics. It is established that the diffusion can proceed by two mechanisms, which results in deviations from the Arrhenius law. The first mechanism is related to the formation of chains of atomic displacements between two dislocation cores along the boundary (for high-angle boundaries, between the regions of contraction and extension); the second mechanism consists in a cyclic exchange of atomic sites near the same dislocation core (for high-angle boundaries, near the defect region).