The influence of neutron radiation on the yield stress and on some activation parameters of polycristalline vanadium

Abstract

On neutron irradiated polycrystalline vanadium a thermal activation analysis was performed using the stress relaxation method. Irradiation influences both the thermal and the athermal stress component. The radiation hardening at low and intermediate doses can be described according to the dispersed barrier model by a (φ t) 1 2 -dependence. For high doses saturation phenomena are observed. The rate determining process is not influenced qualitatively by irradiation at doses up to 1 × 10 18 n/cm 2. The strength of the rate determining obstacles is reduced at low doses, perhaps as a result of the formation of oxygen-radiation defect complexes. Whereas interstitial oxygen atoms, elementary radiation defects, and complexes composed from both suffer a contribution to the thermal stress component, visible defect clusters in this case probably affect only the athermal stress component. As one can imagine, these findings are dependent on the content of relevant interstitial impurities. In this case the dominating role being played by the oxygen atoms.