One of the most common methods used to measure the diffusivity D of H in solids was to determine the out-gassing kinetics of H-charged bodies. The simple out-gassing rate laws depend for their strict validity upon the assumption that the as-charged H-profile in the sample was uniform, and that this profile was not perturbed in the heat-up phase before the out-gassing pressure was recorded. These experimental conditions were difficult to

fulfill, especially at temperatures where D was large. It was shown by computer experiments that the validity of D-values extracted from out-gassing kinetics was not noticeably affected; even when deviations from these boundary conditions were large.

Simulation Calculations of the Outcome of H-Diffusivity Measurements Deduced from the Out-Gassing of Samples with Differing Initial Concentration Profiles. D.Zang, R.B.McLellan: Physica Status Solidi A, 2003, 195[2], 401-4