The effect of H upon the average dislocation velocity in single crystals was investigated by using the etch-pit technique. It was found that the velocity was markedly decreased by high H contents, and that the tension/compression asymmetry of the dislocation velocity was reversed. A detailed observation of the dislocation structure indicated that the motion of edge super-kinks was markedly inhibited by solute H atoms. The results constituted strong evidence for the mechanism of H strengthening in metals. The interaction between the solute H and edge dislocations also shed light on the role which was played by kinks in producing the flow stress anomaly in NiAl.

A Dramatic Decrease of the Dislocation Velocity in Ni3Al Single Crystals under the Influence of Hydrogen. Jiang, C.B., Li, H., Tan, J., Wu, S.D., Rong, L.J., Patu, S.: Intermetallics, 2001, 9[4], 355-60