The separation effect of radiation-induced defects in nickel

Pure nickel, the model material for austenitic steels used in reactors, with an electrical resistivity ratio of $\rho_{300 K}/\rho_{4.2 K}\sim$ 300 has been investigated under electron and neutron irradiation at $T_{\mathrm{IRR}}\sim$ 320–340 K. Three of its states have been subjected to irradiation: a recrystallized state at 873 K, a deformed one to 90%, and an annealed one at 450 K after deformation to remove deformation-induced vacancies. It is has been experimentally shown that neutron and electron irradiation of the deformed nickel results in the separation of radiation-induced defects. This separation occurs because a significant portion of the radiation-induced interstitial atoms is captured by dislocation sinks and does not participate in recombination with vacancies. As a result, the concentration of accumulated vacancies in the deformed nickel can exceed their concentration in the annealed nickel and be almost twice as high. At higher doses of neutron irradiation, above 10$^{18}$ cm$^{-2}$, separation does not occur, since vacancy sinks in the form of clusters are more powerful than dislocation sinks.