The diffusivity of H in 2 series of solid solutions (1 to 8at%Ti, 1 to 10at%V) was measured by using electrolytic methods (single current pulse and potentiostatic) at temperatures of between 273 and 350K. It was found that the diffusion of H obeyed the Arrhenius relationship (table 155) over the temperature range which was studied. Substitutional solute atoms created trapping sites for H, and the H diffusivity steadily decreased as the concentration of substitutional solute was increased. It was estimated that the increased diffusivity which resulted from solute-induced lattice dilation was insignificant in comparison with the retarding effect of trapping. The trapping sites were shallow (about 3kJ/mol), as compared with the trapping sites which were created by dislocations in Pd. The thermodynamic behavior of the systems could be described in terms of Boltzmann statistics. No indication was found that the condensation of interstitial species into low-energy sites occurred.

The Diffusion of Hydrogen through Palladium-Titanium and Palladium-Vanadium Solid Solutions. M.Yoshihara, R.B.McLellan: Journal of Physics and Chemistry of Solids, 1982, 43[6], 539-45

Table 155

Arrhenius Constants for H Diffusion in Pd-Ti and Pd-V Alloys

Table 156

Diffusivity of H in Pd-Y Alloys