In austenitic steels used for light water reactors, neutron irradiation induces the microchemical and microstructural changes in matrices and around grain boundaries, which are related to various property changes, such as irradiation hardening and irradiation assisted stress corrosion cracking (IASCC). These phenomena may also be important in fusion reactors, if austenitic steels are used in core components. The grain boundary segregation and the microstructural development depend on irradiation conditions, such as dpa levels, helium contents and temperatures, etc. The effects of helium, however, have not yet been clarified. This paper presents microchemical and microstructural changes in 304SS and XM-19 steel implanted with helium and irradiated with proton. The TEM disks were implanted with helium of 15 appm and irradiated with 2 MeV H+2 ion to about 1 dpa at 300°C. Chemical analysis was performed using Field Emission Transmission Electron Microscope (FE-TEM) and showed that the depletion of chromium at a grain boundary. However, the amount of the depletion strongly depended on both chemical compositions of the steels and helium contents. Observation by TEM also indicated that small cavities generated in both of the irradiated steels. Nucleation of these cavities may be mainly due to the effects of implanted helium prior to H+2 ion irradiation.
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Materials Science(all)
- Nuclear Energy and Engineering