It was pointed out that there had been relatively few determinations of the diffusivity of H in this material. The apparent H diffusion coefficient could however be easily measured by using the technique of sub-surface micro-hardness profiling after cathodic hydrogen charging. The technique was used here in order to determine the diffusivity of H in stoichiometric samples, and in material which was alloyed with Cr and Ti (table 9). The diffusivities were estimated at 298K, on the basis of micro-hardness profiles, after cathodic H charging in 0.05mol/1 H2SO4 solution.

Hydrogen Diffusivity in Iron Aluminides Determined by Subscale Microhardness Profiling P.Banerjee, R.Balasubramaniam: Scripta Materialia, 1998, 39[9], 1215-9

Table 9

Diffusivity of H in Fe3Al-Based Alloys at 298K