Effect of hydrogen on dislocation behavior in Ni-Cr alloys

The effects of hydrogen on dislocations in Ni-Cr alloys have been investigated by TEM observations using single crystals. The deformation mode of Ni-Cr alloys is characterized by planar dislocations in the absence of hydrogen. However, hydrogen charging changed the dislocation configurations to promote curved dislocations, where the Shockley partials frequently constrict to make nodes and cross-slip. The hydrogen-affected dislocations are enhanced with increasing Ni content. The effect of hydrogen on superdislocations of Ni2Cr superstructure has been also investigated using an aged alloy. While the deformation mode in Ni2Cr superlattice is classified as 5 variants of superdislocation triplets and one variant of ordinary dislocations, the hydrogen charging has preferred the ordinary dislocations. The results suggest that the charged hydrogen changes the local plasticity to affect the deformation dynamics in Ni-Cr alloys.