A technique which involved the combination of segregation experiments with a H permeation technique was used to investigate the H-stimulated segregation of impurities on the metal surface. The diffusivity of S in the bulk Ni was determined at 923 to 1123K; with and without H (figure 30). It was found that H intensified S segregation on the Ni surface. This effect of H was explained in terms of substitutional solid-solution, with H as an interstitial impurity, while taking account of various atomic configurations among the nearest neighbours.

O.G.Romanenko, V.P.Shestakov, I.L.Tazhibaeva: Physical Review B, 2000, 61[7], 4934-40

Figure 30

Diffusivity of S in Ni

(a: with H, b: without H)