Characterizing accelerated precipitation in proton irradiated steel

Ion irradiation provides a promising substitute to neutron tests for investigating the effects of radiation on materials for fission and fusion reactor plants. Here we show proton irradiation can quantitatively reproduce precipitation that leads to embrittlement in reactor pressure vessel steels, at dose rates 104 times greater than experienced in fission reactor operation. Small-angle neutron scattering (SANS) is used to characterize precipitate size distributions in copper-containing steels irradiated to average doses of similar or equal to 7 mdpa with 5 MeV protons. Comparing our results with the literature on reactor pressure vessel steels containing >= 1 at.% nickel, we find a power-law scaling of dose with exponent 0.25-0.30 accounts for the effects of dose rate on precipitate volume fraction over 6 orders of magnitude in dose rate. In conjunction with dose rate, carbon is identified as performing a leading role in determining precipitate sizes, adding to the known effects of nickel, manganese and irradiation temperature. We discuss the composition of precipitates inferred from SANS, taking previous atom probe tomography studies into consideration. (C) 2021 Published by Elsevier B.V.

Automated summary

Ion irradiation is a promising alternative to neutron tests for studying the effects of radiation on materials in fission and fusion reactor plants. Proton irradiation has been shown to quantitatively reproduce precipitation leading to embrittlement in reactor pressure vessel steels, even at dose rates significantly higher than those experienced in fission reactor operation. The study also highlights the significant impact of dose rate and carbon content on precipitate sizes in these steels, alongside the known effects of nickel, manganese, and irradiation temperature.