The H permeability of Ni and ordered Ni-(0 to 25%)Mn alloys was studied. In pure Ni, the activation energy for permeation was equal to 31.0kcal/mol at temperatures of 300 to 360C, and equal to 24.0kcal/mol at 360 to 800C. The addition of up to 18%Mn decreased the activation energy and increased the permeability. The addition of 20 to 25%Mn decreased the permeability, and the temperature dependence of the permeability exhibited a complex behavior; thus reflecting the destruction of long-range order. The temperature dependence of the diffusivity was essentially the same for pure Ni and for Ni alloys with up to 18%Mn. At Mn additions of 20 to 25%, the activation energy for diffusion increased and the diffusivity decreased. This was attributed to short-range ordering in the alloys.

J.P.Simakov, P.V.Geld, M.M.Shteinberg, V.A.Goltsov: Uch. Zap. Perm. Gos. Univ., 1968, 194, 102-9