Deformation microstructure of neutron-irradiated pure polycrystalline vanadium

The deformation microstructure of irradiated pure vanadium has been investigated by transmission electron microscopy. Dislocation pileup on grain boundaries were observed in the deformed specimens irradiated to 0.012 dpa, indicating that the source of channeling could not be grain boundary only. TEM analysis suggested a relationship between tensile direction and channeling-occurred grain: there is a tendency that directions of the applied stress with greater resolved shear stress lie on the trace containing [0 1 1] and [1 1 2] directions. Channel width is wider in case the angle between tensile direction and dislocation slip direction is close to 45°. There is a dose dependence on the correlation between channel width and resolved shear stress, the slope of this correlation decreased with increasing dose. It is suggested that the loss of work hardening capacity in irradiated pure vanadium could be mainly due to dislocation channeling locally formed with high resolved shear stress.