Point defect behavior in electron irradiated V-4Cr-4Ti alloy

To investigate the migration behavior of interstitials and vacancies in vanadium alloy V-4Cr-4Ti, high purity V alloys were irradiated with 2 MeV electrons using a high voltage electron microscope (HVEM) and 28 MeV electrons using a electron linear accelerator. Interstitial type dislocation loops formed quickly in all cases of HVEM irradiation. The saturation density of the dislocation loops was independent of irradiation temperature and defect production rate at temperatures in the range of 323-448 K. However, the logarithm of saturated dislocation loop density was inversely proportional to the irradiation temperature, and dislocation loop density was directly proportional to the square root of the defect production rate above 448 K. The dissociation energy of the interstitial-impurity complex in V-4Cr-4Ti alloy was estimated to be 1.1 eV from the HVEM experiment. It was found from positron lifetime measurements that the vacancies form vacancy clusters at 373 K