SELF-ION IRRADIATION OF FCC METALS TO ELUCIDATE PRIMARY RECOIL ENERGY-DEPENDENCE OF DEFECT STRUCTURE DEVELOPMENT DURING NEUTRON-IRRADIATION

Irradiation effect with neutrons is generated from the superposition of recoils with a wide energy distribution, an knowledge of the effect from each recoil is essential. Self-ion irradiation is performed for fcc metals and induced defect structures are analyzed placing the prime interest in the variation of defect structures within the same ion energy and its variation with the ion energy. Mainly discussed are the data on silver as a typical material with closely spaced subcascades. Tendency for saturation of vacancy cluster formation is found to start at low irradiation dose, as low as 10(15) ions/M2, and the intercascade reaction is discussed from this dose dependence. An appreciable percentage of incident ions is found not to contribute in vacancy cluster formation. A wide variation of the formation of vacancy cluster groups was found for the same ion energy. Intracascade/intersubcascade reactions is discussed from the variation of vacancy duster size and the number of the dusters in groups. A method is proposed to construct neutron irradiation induced defect structures from ion irradiation data.