1179. 電子線と中性子によるFe-Cuモデル合金の照射硬化

抄録

In addition to fast neutron, thermal neutron and gamma-ray also contribute to the irradiation induced embrittlement of reactor pressure vessel steels. Although there is a possibility that gamma-ray induces embrittlement more efficiently than fast neutron, the irradiation effect of gamma-ray has not been fully clarified. In this study, to simulate hardening by gamma-ray irradiation, comparative experiments on irradiation hardening by 2.5 MeV electrons and by neutrons were performed for Fe-Cu model alloys. During these irradiations, temperature and dose rate were accurately controlled. We obtained the dose dependence and the temperature dependence of irradiation induced hardening. The growth of Cu clusters with increase in irradiation dose was examined by using the small angle neutron scattering measurements. Although the electron irradiation hardening was initiated slightly earlier than that of the neutron irradiation, the differences in hardening between electron and neutron irradiations were very small on a displacement-per-atom (dpa) basis. The growth of Cu clusters with increase in irradiation dose was a principal cause of hardening, and it became saturated before the doses reached 10^-3 dpa. The present results suggest that, from an engineering point of view, both the gammaray induced and neutron induced hardening can be well scaled by using dpa as an index of irradiation dose.