Modulated permeation experiments were carried out on foils of cold-worked material at temperatures of between 373 and 920K. The frequency response of the permeation flux exhibited a characteristic form, and permeation and trapping data were deduced by fitting the model to experimental data. It was noted that the degree of trapping decreased as the extent of annealing was increased and decreased as the pressure was increased. It was suggested that trapping sites had been introduced by cold-working, but were not directly associated with the accumulation of H gas in micro-voids. It was proposed that dislocation networks which formed around thoria particles were responsible for H-trapping in Ni-ThO2; with an associated energy of 40kJ/mol. Trapping was also detected, in cold-worked Ni, at much lower temperatures than in Ni-ThO2.

A.K.Altunoglu, N.S.J.Braithwaite: Metallurgical and Materials Transactions A, 1996, 27[9], 2495-503