Suppression of the radiation hardening and embrittlement of International Thermonuclear Experimental Reactor materials by multiple intermediate annealing

The paper presents the results from an experimental study on the effect of neutron irradiation in the ‘irradiation–annealing–irradiation (IAI)’ regime on the radiation hardening and embrittlement of pure copper. An ampoule with samples was irradiated at T in=150 °C in the RBT-6 reactor in the following regime: ‘irradiation to 0.004 dpa+annealing at 250 °C+irradiation to 0.004 dpa+···+···’, 15 IAI cycles in all. The experiment showed that the IAI cycles result in suppression of the radiation hardening. By using the Orowan–Seeger model of hardening, we have obtained analytical dependences demonstrating that the hardening value in the cycles is determined only by the initial hardening level during the first irradiation and by the function f(a) n depending on the number n of cycles and the cluster annealing efficiency a. The calculated values of sample hardening after 15 IAI cycles agree well with the experiment.