The synergistic effect of hydrogen and helium implantations in forming H2 molecules in a Fe-12 wt.%Cr-ODS steel characterized by Raman spectroscopy and SIMS

Oxide-dispersion strengthened ferritic steels (ODS) are candidates for a use as first-wall materials in future fission reactors. This application will lead to neutron bombardment and associated helium and hydrogen production by transmutation. The synergistic effects of irradiation damage, helium and hydrogen in a Fe-12 wt.%Cr-0.4 wt.% Y2O3 steel are studied via ion irradiations of this material by 24 MeV Fe8+/600 keV H+ and 1.0 MeV He+/600 keV H+ dual beams, H+ single beam and Fe8+/He+/H+ triple beam. Subsequent analyses of hydrogen in the irradiated ODS by secondary-ion mass spectrometry (SIMS) and Raman spectroscopy were carried out to profile hydrogen and to characterize the formation of the di-hydrogen molecule (H-2). The results show that irradiation damage and helium play a role in the retention of hydrogen in the specimen. The formation of the H-2 molecule is observed only when the ODS steel is co-irradiated with H and He beams in dual or triple modes.