The short-range and long-range diffusion of H was studied by using magnetic after-effect and thermal desorption spectroscopic techniques. It was found that the substitution of Ga for Fe greatly reduced the up-take and diffusion of H. The Fe17Sm2 exhibited a H-induced magnetic after-effect relaxation maximum at 190K, with a mean activation enthalpy of 0.48eV and a pre-exponential factor of 5 x 10-12s. The results were explained in terms of differing interstitial sites for H.

N.Mommer, J.Van Lier, M.Hirscher, H.Kronmuller: Journal of Alloys and Compounds, 1998, 270[1-2], 58-62

Figure 29

Diffusivity of Si in Fe-Si Alloys

(a: 12%Si, b: 5%Si)