Deformation microstructure of neutron-irradiated pure polycrystalline metals

The effects of neutron-irradiation near 80 °C on the deformation behavior of pure polycrystalline metals vanadium (body centered cubic, BCC), copper (face centered cubic, FCC) and zirconium (hexagonal close packed, HCP) have been investigated. Dislocation channel deformation is observed in all metals, and is coincident with prompt plastic instability at yield. Dislocation pileup was observed at grain boundaries in the deformed vanadium irradiated to 0.012 dpa, indicating that channel formation could lead to dislocation pileup and the resulting stress localization could be a source of grain boundary cracking. TEM analysis suggests that the loss of work hardening capacity in irradiated V, Cu, and Zr at higher doses is mainly due to dislocation channeling in local regions that experience a high resolved shear stress.