The behavior of hydrogen in Fe–Ni alloys was studied using the tritium evolution technique. Applying a three-dimensional analytical solution of Fick’s diffusion equation to the tritium evolution curve from disk shaped samples, hydrogen retention and apparent diffusion coefficients in Fe–Ni alloys with Ni content from 6 to 50at% were determined around RT. In γ phase region, diffusion coefficients were not appreciably changed and increased with lattice parameter. In the α′ phase region, two diffusion components were distinguished: For fast diffusion components, diffusion coefficients have quite good agreement with the literature value and decreased with increase of lattice parameter. The slower diffusion components were likely attributable to retained γ phase precipitates or Ni3Fe dispersed in the α′ matrix and must be very important to understand hydrogen embrittlement and tritium safety handling.

Hydrogen Diffusion in Fe–Ni Alloys Around Room Temperature. T.Otsuka, S.Sasabe, T.Tanabe: Journal of Nuclear Materials, 2009, 386-388, 884-7