Special features of grain-boundary diffusion in nanostructural and submicrocrystalline materials caused by structural heterogeneity of grain boundaries

Mechanisms of grain-boundary diffusion are analyzed based on models of structurally heterogeneous grain-boundaries and multipath diffusion in a system of structural elements responsible for accelerated mass transfer. The effective (averaged) coefficients of grain-boundary diffusion are obtained in models of continuous and discrete distribution of partial activation energies. The results of originally processed diffusion data in some submicrocrystalline materials are presented. The conclusion is drawn that, at low temperatures, the mass transfer in these materials is achieved through a small portion of active diffusion paths, presumably via grain triple junctions.