Effects of impurities on microstructural evolution and deformation process of ion-irradiated V-Cr-Ti alloys

Microstructural examination and microhardness test were carried out for unalloyed vanadium, V-5Ti, V-4Cr-4Ti alloys irradiated with 4 MeV Cu ions at temperatures from 200 to 600degC. In order to investigate the impurity effect, high purification technique was used. Impurity effects can be seen in the nucleation and growth processes of voids in unalloyed vanadium and those of Ti(OCN) precipitates in V-5Ti. The changes in microstructure due to interstitial impurity could not be seen in V-4Cr-4Ti after the irradiations below 300degC. The effect of impurity for irradiation hardening in ion-irradiated V-4Cr-4Ti alloys could be seen at 400degC, but it could not be seen at 200 and 300degC. On the other hand, dislocation channels were observed at 200 and 300 degC, and the total length of dislocation channels became larger as the impurity level increased. It can be considered that there was practically no correlation between irradiation hardening and total length of dislocation channels due to impurity effects. (author)