The permeation behavior under oscillating pressure conditions was studied. From the results, it was deduced that the diffusivity at 500 to 1000K could be described by:

D (cm2/s) = 4.28 x 10-4 exp[-1.54(kcal/mol)/RT]

The ratio of the diffusion coefficients of D and H approached unity with increasing temperature.

A.Tahara, Y.Hayashi: Journal of the Japan Institute of Metals, 1985, 49[4], 248-52