The occurrence of H-induced lattice migration, which led to rearranged lattices, was considered on the basis of recent studies of Pd-rich alloys. In initially homogeneous face-centered cubic Pd-based alloys, H heat-treatment caused segregation. In the case of Pd-Rh alloys, the segregation was clearly due to the miscibility gap of the system. This occurred at both low H contents and high (873K) temperatures or moderate (473K) temperatures and relatively high H contents. However, in the case of Pd-Ni and Pd-Pt alloys segregation which arose from H heat-treatment occurred only at moderate temperatures and relatively high H contents. In the case of Pd-Ni, H heat-treatment at high temperatures promoted metal atom diffusion which led to the elimination of compositional variations in an initially inhomogeneous alloy. It was noted that dissolved H played a dual role in some of the alloys. That is, it catalyzed metal atom diffusion and also affected the equilibrium state.

T.B.Flanagan, H.Noh: Journal of Alloys and Compounds, 1995, 231, 1-9