Neutron irradiation damage in molybdenum

Abstract

Abstract Molybdenum, ranging in resistivity ratio (ρ293°K/ρ4·2°K) from 150 to 8000, has been neutron irradiated at 77°K and 473°K to integrated fission doses of ∼1020 n. cm−2 ∼7 × 1019 n. cm−2, respectively. A detailed electron microscope study has been made of the damage structures both before and after a post-irradiation anneal of one hour at 1173°K. It is found that the defect cluster topology in the irradiated specimens is a sensitive function of both material purity and irradiation temperature. A model has been discussed specifically to explain the topology of interstitial clusters in which impurity assisted nucleation dominates.