Institute for Problems of Mechanical Engineering, Russian Academy of Sciences,
Bolshoj 61, Vas. Ostrov, St. Petersburg 199178, Russia
| A theoretical model is suggested which describes percolation of enhanced diffusion along triple junctions of grain boundaries in nanocrystalline materials with very small grains. The effective diffusion coefficient is defined and calculated which takes into account a distribution of diffusivities among triple junctions that form a network in a nanocrystalline solid. It is shown that the effective diffusion coefficient is lower than the average diffusion coefficient in nanocrystalline materials. |
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