Isochronal annealing experiments were performed on material bombarded with H or He ions in order to study the interactions between gas atoms and vacancy clusters. The energies of the H and He ions were 1.0 and 3.3MeV, respectively. The total dose was 1.0 x 1021H/m2 (0.2dpa) or 9.6 x 1019He/m2 (0.3dpa), and the irradiation temperature was 300C. Positron annihilation lifetime and coincidence Doppler broadening measurements were carried out after irradiation and annealing (1h) up to the complete-recovery temperature. Micro-voids were detected after H or He ion bombardment. Characteristic differences were found mainly in the recovery of vacancy-type defects. The recovery of vacancy-type defects introduced by H-ion bombardment was completely finished at 450C, while that produced by He-ion bombardment was finished at 1000C. This suggested that H-vacancy complexes were less stable than He-vacancy complexes. The vacancy clusters formed by He-ion irradiation grew after annealing at 600C, and this was attributed to the emission of He atoms from small He-vacancy clusters, coalescence between free vacancies and vacancy clusters, and the migration and coalescence of He bubbles.

The Recovery of Gas-Vacancy-Complexes in Fe Irradiated with High Energy H or He Ions. T.Ishizaki, Q.Xu, T.Yoshiie, S.Nagata: Materials Transactions, 2004, 45[1], 9-12