Effect of oxygen impurity on defect agglomeration and hardening of neutron-irradiated niobium

Abstract

The density and diameter distribution of defect clusters and loops in neutron-irradiated niobium containing either 10, 68, or 185 ppm (wt.) of oxygen impurity was determined for neutron doses up to 4 × 1019 neutrons/cm2. These data were correlated with the increase of resolved shear stress of irradiated niobium single crystals containing oxygen impurity. Based on a dispersed barrier hardening model, the hardening of niobium irradiated at 30-50°C was interpreted to be due primarily to loops and clusters with diameters less than 70 Å. © 1973.