The recovery of excess dissolved H was studied by using a modified Schultz H-quenching method. Two recovery stages in the electrical resistance were found. The lower-temperature stage was presumed to arise from trapping and/or clustering of H atoms within the specimens. The higher-temperature stage was due to the escape of H from the specimens. This stage was closely studied by means of isothermal annealing over a wide temperature range, using various specimen sizes. All of the results could be fitted to a generalized curve. The diffusivity of H in Ni was described by:

D (cm2/s) = 1.90 x 10-3 exp[-8890/RT]

Diffusion of Hydrogen in Hydrogen-Quenched Nickel. K.Yamakawa, F.E.Fujita: Japanese Journal of Applied Physics, 1977, 16[10], 1747-52