A novel in-situ 59Ni(n,a) reaction He-implanter technique is described, that was used to characterize the effect of the He/dpa ratio on microstructural evolution and changes in the flow properties of various materials at fusion relevant conditions. Irradiations in the High Flux Isotope reactor (HFIR) resulted in a-implantation from thin 1 to 5 µm NiAl coatings on TEM discs producing a uniform He concentration of 5 to 50 appm He/dpa to a depth of 5 to 8 µm. Initial post-irradiation TEM observations of MA957 irradiated to 9 dpa and 380 appm He at 500 ºC provide strong evidence for the existence of high density of small = 1 nm size bubbles trapped on nano-scale YTiO clusters. In contrast, similar irradiations of Eurofer 97, described in a companion paper, produce a lower number density of larger cavities, which may be a mixture of bubbles and voids.
Revised: October 11, 2007 |
Published: August 1, 2007
Citation
Yamamoto T., G.R. Odette, P. Miao, D.T. Hoelzer, J. Bentley, N. Hashimoto, and H. Tanigawa, et al. 2007.The Transport and Fate of Helium in Nanostructured Ferritic Alloys at Fusion Relevant He/DPA Ratios and DPA Rates.Journal of Nuclear Materials 367-370.PNNL-SA-55263.doi:10.1016/j.jnucmat.2007.03.047