The diffusion coefficients (table 147) were measured, at temperatures of between 0 and 50C, by using an electrochemical method. The H content was less than 0.1at%, and its diffusivity was markedly decreased by Nb additions. This effect was attributed to a trapping phenomenon, and this assumption was supported by the observation that there was no dependence of the diffusivity upon the H concentration. The addition of Cu also decreased the H diffusivity, but to a lesser extent. A change in the diffusion activation energy was detected in the case of the 6.5%Nb alloy. The activation energy was increased by 7kJ/mol with respect to that for pure Pd.

Diffusivity of Hydrogen in Dilute Alloys of Copper and Niobium in Palladium. R.Kirchheim, R.B.McLellan: Acta Metallurgica, 1980, 28[11], 1549-54

Table 148

Diffusivity Parameters for H in Pd-Er Alloys

Table 149

Parameters for D and H Diffusion in Pd-Ni