Exact and approximate expressions were derived for the mean square penetration depth in grain boundary diffusion. The penetration depths in boundary diffusion were found to be functionally different to those in lattice diffusion, in that the former was t-dependent while the latter was almost t-dependent. In general, the penetration depths for grain boundaries was some orders of magnitude greater than the penetration depths for the lattice.

Y.T.Chou, Y.Z.Li, C.T.Liu: Metallurgical and Materials Transactions A, 1996, 27[11], 3473-7