An electrochemical method was used to measure the permeation of H in electrolytic Fe (0.001C). The transient response was analyzed with particular regard to the trapping effect of impurities and to surface effects of the environment. In order to determine the intrinsic H diffusivity, diffusion theory was applied only to the initial permeation transient; which represented the fast component that was due to lattice diffusion. Errors which were caused by surface reactions were eliminated by considering the size-dependence of the apparent diffusivity. The true H diffusivity in Fe was deduced to be 7 x 10-5cm2/s at 20C. This value was independent of defects in the specimen and of the measurement conditions.

S.Asano, Y.Fujishima, N.Ohtani: Nippon Kinzoku Gakkaishi, 1973, 37[3], 301-6