Freely-migrating-defect production during irradiation at elevated temperatures

Radiation-induced segregation in a Cu–1 at. % Au alloy was investigated using in situ Rutherford backscattering spectrometry. The amount of Au atom depletion in the near surface region was measured as a function of dose during irradiation at 350 °C with four ions of substantially different masses. Relative efficiencies for producing freely migrating defects were evaluated for 1.8-MeV ${}_{}{}^1{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{84}{}_{}{}^{}\mathrm{Kr}$ ions by determining beam current densities that gave similar radiation-induced segregation rates. Irradiations with primary knock-on atom median energies of 1.7, 13, and 79 keV yielded relative efficiencies of 53, 7, and 6 %, respectively, compared to the irradiation with a 0.83-keV median energy. Despite quite different defect and host alloy properties, the relative efficiencies for producing freely migrating defects determined in Cu-Au are remarkably similar to those found previously in Ni-Si alloys. Hence, the reported efficiencies appear to offer a reliable basis for making quantitative correlations of microstructural changes induced in different alloy systems by a wide variety of irradiation particles.