The diffusion behavior was studied by performing permeation measurements on fine-grained foils which had been produced by electrodeposition. The permeation data were analyzed by using a modified version of the Hart equation. The grain boundary diffusivity at 30C was at least 3 x 10-12m2/s. This was a factor of 40 times greater than the lattice diffusivity. However, the analysis indicated that a 1000-fold increase might not be unreasonable. The activation energy for grain boundary diffusion was 30kJ/mol. This was approximately equal to 75% of the activation energy for H diffusion in Ni monocrystals.

T.M.Harris, R.M.Latanision: Metallurgical Transactions A, 1991, 22[2], 351-5