Use of high energy ions for the mechanistic study of irradiation embrittlement in pressure vessel steels using Fe–Cu model alloys

To study the mechanism of irradiation embrittlement in pressure vessel steels, it is necessary to sort out the irradiation parameter dependence, which is particularly complex in the neutron irradiation case. Irradiation with high energy heavy ions allows us to carry out single parameter experiments, thereby providing basic data for the modelling of irradiation embrittlement. In this study using Fe–Cu model alloys, three important parameters; ion fluence, irradiation temperature and copper concentration are selected and irradiation induced Vickers hardness change is measured. The hardness change shows a steep increase with fluence after a certain incubation dose. The irradiation temperature dependence of hardness change at fixed fluence shows a peak at around 250–300 °C. Shift of irradiation temperature dependence from neutron irradiation case may be ascribed to the difference in dose rate. Copper concentration dependence shows that the change in hardness seems to depend on the square root of copper concentration. This supports the dispersed barrier hardening model.