Effect of interaction between H and He on micro-defects in Fe9Cr alloy investigated by slow positron beam

Abstract

In order to investigate the effect of interaction between H and He ions on micro-defects in Fe9Cr alloy, well-annealed Fe9Cr alloy were pre-damaged firstly with 1 MeV Ni ions to a dose of 3.4 × 1013/cm2, and then irradiated with single (H or He) ion beam and sequential (H/He or He/H) ions beam. The irradiation were performed with 50 keV H ions, 80 keV He ions with doses of 1 × 1016/cm2 and 2 × 1015/cm2 at 723 K, respectively. Results of slow positron beam show that the S parameter decreased obviously after single (H or He) ions beam irradiation compared to the pre-damaged specimen, which indicate H or He (Hn or Hen) clusters deposit at the damage area caused by Ni ion irradiation and they occupy vacancy sites (Vm), resulting in the formation of numerous HnVm or HenVm clusters. The S parameter induced by He/H ions sequential irradiation didn't change significantly compared to that by single He ion irradiation. However, obvious increment of the S parameter induced by H/He ion sequential irradiation is higher than that induced by singe H ion irradiation. The binding energy of HnVmHe is larger than HenVmH, and it is difficult for subsequent H ions irradiation to decompose the HenVm complexes.