The effect of lattice strain upon diffusion was investigated at 23 to 68C by using electrochemical methods. The solubility of H was increased slightly by deformation. The activation energy for H diffusion was unaffected by deformation, and the diffusion data could be described by:

D (cm2/s) = 1.32 x 10-3 exp[-5.35(kcal/mol))/RT]

in the annealed state. The activation energy decreased slightly with increasing deformation; thus suggesting that the interaction energy of H atoms with trapping sites was very small. It was shown that the H content had a marked effect upon the mechanical properties. Thus, the tensile elongation was increased by adding H to below the solubility limit, but further additions of H resulted in the formation of hydrides in the matrix, and reduced the tensile elongation. It was found that the effects of H additions were much more marked in the cold-worked state than in the annealed state.

Hydrogen Diffusion and Effect on the Mechanical Properties in Annealed and Cold-Worked Palladium. H.Hasegawa, K.Nakajima: Journal of the Japan Institute of Metals, 1977, 41[8], 813-20

Table 126

Parameters for H Diffusion in β-Pd as a Function of Pressure