By using combined electrochemical and gas-volumetric techniques, a study was made of the permeation of H through Fe specimens of various degrees of purity. The results indicated (table 30) that O concentrations of 150 to 400ppm and Ni concentration of up to 0.04wt% had no measurable influence upon the H diffusion coefficients; as calculated from the time-dependence of the permeability data. However, Ni concentrations above 0.04wt% - as well as increasing concentrations of other impurities - resulted in a decreased diffusion coefficient. Within the range of I = 0 to 0.5wt% of impurities, the diffusivity of H at 25C could be described by:

D (cm2/s) = 4.3 x 10-6 exp[-4.8 I(wt%)]

W.Dresler, M.G.Frohberg, H.G.Feller: Zeitschrift für Metallkunde, 1972, 63[2], 94-8