Hardening and microstructure of model reactor pressure vessel steel alloys using proton irradiation

摘要

As part of a broad effort to understand the mechanisms of irradiation embrittlement in reactor pressure vessels steels, irradiation hardening and microstructural evolution in simple model Fe-0,9Cu-1.0Mn, Fe-0.9Cu and Fe alloys irradiated with 3.2 MeV protons at 300°C are compared to the corresponding changes in hardening produced by neutron irradiation over a similar dose range of 0.0004 to 0.015 dpa. In the case of the proton irradiated samples, Vickers hardness was measured at a 25 g load and the microstructures were characterized using small angle x-ray scattering (SAXS). In spite of the much higher dpa rate for protons (3 × 10{sup}-7 dpa/s compared to neutron rates of about 10{sup}-9 to 10{sub}-10 dpa/s) as well as very different primary recoil spectra, the observed hardening-dose response is very similar in both cases. The large increase in hardness in the alloys with 0.9% copper, and the SAXS data are consistent with precipitation of coherent copper-rich features accelerated by irradiation enhanced diffusion, as well as a much smaller contribution presumably from defect clusters that do not require the presence of copper.