ON THE NATURE OF TEM-OBSERVED DEFECT CLUSTERS IN LOW-DOSE NEUTRON-IRRADIATED AND ION-IRRADIATED CU, AG AND AU AT ROOM-TEMPERATURE

The nature and the depth of TEM-visible defect clusters were precisely analyzed in 40 keV Cu+-ion and 14 MeV neutron-irradiated thin foil Cu, Ag and Au at room temperature. Results of ion irradiation showed that the fraction of vacancy-type defect clusters increased with the dose and decreased with specimen thickness, leading to the conclusion that vacancies produced by displacement collision cascades thermally migrate toward vacancy-type defect clusters created by collision cascades, and that the probability of the loss of interstitial atoms from the surface is small in a thicker section of thin foil specimens. The same thickness dependence was found in a 14 MeV neutron-irradiated Au in which vacancy-type stacking fault tetrahedra and vacancy-type dislocation loops were dominant in a thinner section and considerable number of interstitial-type dislocation loops were formed in a thicker section.