The effects of H charging on the dislocation behaviour in Ni-Cr binary alloys were investigated by means of transmission electron microscope observations using single-crystalline specimens. The deformation mode of Ni-Cr alloys in the absence of H was

characterized by planar dislocations. However, H charging changed the dislocation configurations to promote curved dislocations, such as dislocation loops and dipoles. The H-affected dislocation configurations were enhanced with increasing Ni content and reducing Cr content. Weak-beam images showed that the Shockley partials of the H-affected dislocations frequently constrict to make kinks and cross-slip, as if the dislocations were generated by a thermally activated process. The effect of H charging on super-dislocations of a Ni2Cr superstructure was also investigated using an aged 70Ni-30Cr alloy. While the deformation mode in the Ni2Cr superlattice was classified as five variants of super-dislocation triplets and one variant of ordinary dislocations, the H charging has preferred the ordinary dislocations to the super-dislocation triplets. The results suggested that the charged H changed the local plasticity to affect the deformation dynamics in Ni-Cr alloys, where the influence of H on the plasticity was sensitive to the Ni/Cr concentration and the symmetry of atomic arrangement.

Effect of Hydrogen Charging on Dislocation Behavior in Ni-Cr and Ni2Cr Alloys. K.Miyata: Metallurgical and Materials Transactions A, 2003, 34[6], 1249-57

 Table 5

           Bulk Diffusivity of 51Cr in Ni-15.18Cr-7.76Fe-0.07wt%C