Characterization of proton irradiation-induced defect in the A508-3 steel by slow positron beam

Proton irradiated A508-3 steel samples at room temperature were characterized by slow positron Doppler broadening spectroscopy to investigate the evolution of the irradiation-induced defects. S parameters of the irradiated samples were higher than those of the unirradiated samples. The S–W plot indicated that only one type of defect was presented in all the samples. These defects seem to be the vacancy–impurity complexes (associated with C, H, Mn or Ni) or divacancies. On the basis of the assumption that irradiation induced-defects consist of mono-vacancies, the concentration of these defects (∼1020/cm3) rapidly increases at the low dose (below about 0.15 dpa) and then tends to saturate at high dose (up to 0.35 dpa).

► S–W plot indicated only one type of defect in irradiated samples.
► Irradiation-induced defects seem to be vacancy–impurity complexes or divacancies.
► Density of defects increases rapidly below 0.15 dpa and tends to saturate up to 0.35 dpa.