Electron- and neutron-irradiation effects upon dilute Fe-Cu model alloys of nuclear reactor pressure vessel steels were studied by positron annihilation spectroscopy. It was found that, not only during high-dose neutron-irradiation but also during low-dose electron-irradiation, the aggregation of Cu atoms and vacancies took place and the ultrafine Cu precipitates were formed after post-irradiation annealing at 400C. In spite of large difference in the irradiation doses between the electron- and the neutron-irradiated samples, no significant difference was observed in the isochronal annealing behaviour above 400C of positron annihilation and micro-hardness, indicating that small amount of extra vacancies enhance the aggregation of Cu atoms in Fe during the annealing-out process of the vacancies.

Effect of Electron- and Neutron-Irradiation on Fe-Cu Model Alloys Studied by Positron Annihilation Spectroscopy. Y.Nagai, K.Takadate, Z.Tang, H.Ohkubo, H.Sunaga, H.Takizawa, M.Hasegawa: Journal of Physics - Conference Series, 2011, 265[1], 012007