Cyclicity of the dislocation restructuring in necking in an hcp Zr-Nb alloy

Cyclic dislocation transformations are detected in the deformation macrolocalization zone during tension of a Zr-1% Nb alloy, and this cyclicity is accompanied by periodic relaxation of internal stresses as a result of the decomposition of sub-boundaries and dislocation redistribution. The oscillatory instability of deformation localization in the hardening-softening mode at the parabolic stage of plastic flow in zirconium alloys is found to be related to the cyclicity of dislocation transformations in the macrolocalization zone during its transformation into a neck.