The diffusivity of H in Fe3Al-based alloy samples (5Cr, 0.1Zr, 0.05B) with various grain shapes and sizes was investigated. This showed that the H diffusion coefficients were all similar at a given temperature (figure 9), and indicated that neither the grain shape nor the size affected H diffusion.

Hydrogen Diffusivity in a Fe3Al-Based Alloy. X.Y.Cheng, X.J.Wan: Scripta Materialia, 1998, 38[10], 1505-9

Figure 9

Diffusivity of H in Fe3Al-Based (5Cr, 0.1Zr, 0.05B) Alloy