Microstructure of vanadium alloys during ion irradiation with stepwise change of temperature

To understand the influence of a stepwise change of irradiation temperature on pure vanadium and vanadium alloys, ion irradiation were performed at 473 K to 0.25 dpa and 873 K to 0.5 dpa. In pure vanadium and V–5Cr alloy, shrinkage of interstitial type loops was prominent during irradiation at 873 K. These results were explained by the appearance of a vacancy rich condition during the successive irradiation at 873 K. In Ti-containing alloys (V–5Ti, V–4Cr–4Ti), on the other hand, dissociation of vacancy loops leads to the shrinkage of interstitial type loops and the formation of Ti-enriched precipitates.