Electrochemical permeation experiments were performed on fully-annealed commercial-purity samples of 2 types. Type-I samples were plasma-cleaned and pre-sputtered, and type-II samples were not. Measurements were performed at 25 to 80C. The diffusivity of H could be described by:

D (cm2/s) = 7.93 x 10-4 exp[-7.340(kJ/mol)/RT]

When the diffusion activation energy was evaluated by using the time-lag model, the diffusion activation energy for type-II samples was 22.970kJ/mol. The energy barrier to desorption was lower in type-I samples than in type-II samples.

Y.P.Zheng, T.Y.Zhang: Acta Materialia, 1998, 46[14], 5035-43