Migration and clustering of early-stage irradiation damage in vanadium

The early stages of irradiation damage are characterized by the formation of monovacancy defects and self-interstitial atoms (SIAs). With increasing damage levels, these point defects migrate and eventually cluster to form larger structures such as voids or dislocation loops. Temperature-activated migration of these elementary point defects controls the self-healing processes. In this work, the authors use positron annihilation spectroscopy to monitor the defect evolution in vanadium from 35 K until the full recovery of the irradiation-induced defects at 500 K. They identify recovery stages each related to the migration of a separate defect species: SIAs, mono-vacancies, vacancy clusters, and multivacancy-hydrogen complexes.