Correlation between mechanical properties and Cu precipitates induced by neutron irradiation of Fe[sbnd]Cu alloys

Abstract

It is well known that Cu precipitates are formed by neutron irradiation of FeCu alloys, which are the model alloys of reactor pressure vessels (RPVs), and Cu precipitates increase the yield stress and decrease the total elongation of FeCu alloys. However, the correlation between the formation of Cu precipitates and the mechanical properties of FeCu alloys is not clear. In this study, two model alloys, Fe-0.3Cu and Fe-0.6Cu were irradiated with neutrons at 573 K with up to 6.2 × 1022 neutrons/m2 (E > 0.1 MeV), corresponding to 9.5 × 10−3 dpa (displacement per atom). Cu precipitates were formed in both FeCu alloys even after an irradiation of 1.1 × 10−5 dpa. The Vickers microhardness, 0.2% yield stress, and tensile stress increased, but the total elongation decreased with an increased irradiation dose up to about 4.7 × 10−4 ∼ 2.4 × 10−3 dpa for both alloys. After that, the Vickers microhardness, 0.2% yield stress, and tensile stress decreased with an increased irradiation dose. These changes in the mechanical properties of the alloys are related to the growth of microvoids.