Hydrogen diffusion in Fe–Ni alloys around room temperature

We have revisited hydrogen behavior in Fe–Ni alloys with the tritium evolution technique. Applying a 3D 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 50 at.% are 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 are 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.