Nucleation and growth of dislocation loops in austenitic stainless steels irradiated by fission and fusion neutrons

Abstract

Nucleation and growth of interstitial type dislocation loops were investigated by fusion and fission neutron irradiations with improved temperature control. The density of loops formed by both irradiations increased linearly with fluence. The average size of loops also increased. It was concluded that the loops were nucleated directly by the defect processes in the cascade zone, and not by the reaction among the freely migrating point defects in the matrix. If the efficiency of loop formation is assumed to be directly proportional to the energy of the primary knock-on atom (PKA) produced by the neutron, the threshold energy of 20 keV and the efficiency of loop formation of 0.4% at this energy were obtained.