Permeation through monocrystalline and polycrystalline specimens of fully annealed material was measured, at 230 to 300K, by using an electrochemical method in which alcoholic solutions were used as electrolytes. The resultant permeation curves were analyzed by taking particular account of variations in the H concentration at the cathode surface during measurement. The H diffusion coefficients which were thereby deduced for monocrystalline Fe could be described by:

D (m2/s) = 1.1 x 10-7 exp[-6.70(kJ/mol)/RT]

The data for polycrystalline specimens could not be expressed by using a single Arrhenius equation.

H.Hagi, Y.Hayashi, N.Ohtani: Journal of the Japan Institute of Metals , 1978, 42[8], 801-7