Study of point defect behavior in V–Ti alloys using HVEM

Microstructural evolution and point defect behavior in vanadium, V–5Ti binary alloy and V–4Cr–4Ti alloy have been examined by using a high voltage electron microscope. In order to examine the effects of interstitial impurity atoms, V–Ti alloys with different levels of purity have also been examined. During irradiation, interstitial-type dislocation loops formed and grew in all of the materials. In alloys, the loop number density (CL) was much higher than that in vanadium. In high purity V–4Cr–4Ti, contrary to results from our previous study on vanadium, CL did not significantly decrease or change by purification, indicating solute atoms themselves strongly trap self-interstitial atoms (SIAs). From the temperature dependence of loop density in V–4Cr–4Ti, the effective migration energy of a SIA of 0.50 eVwas obtained. Various observed phenomena are discussed in terms of this activation energy.