Effect of annealing on VmHn complexes in hydrogen ion irradiated Fe and Fe-0.3%Cu alloys

The effect of annealing on VmHn complexes in irradiated Fe-0.3%Cu alloy was investigated using positron annihilation spectroscopy based on a slow positron beam. The formation of vacancy-type defects due to the 0.1 dpa irradiation would lead to the increment of the S parameter compared to the unirradiated specimen. A larger number of hydrogen deposited at the damage area and hydrogen atoms (Hn) occupied vacancy sites (Vm), which could lead to the formation of numerous VmHn complexes. The irradiated sample was annealed isochronally for 30 min at 150 °C, 200 °C, 300 °C, 400 °C and 500 °C, respectively. An evident defect peak formed at 150 °C, which meant the VmHn complexes were broken and a larger of hydrogen atoms was escaping. The remaining vacancy-type defect induced the increment of the S parameter. The peaks migrated from the damage area towards to surface region (peaks 1-5). The S parameters in the damage area gradually decreased with the increasing annealing temperature. The shrinkage of vacancy-type defects and the density of defects induced the decrease of S parameters during elevated annealing treatment.159