Formation of defect clusters in nickel and molybdenum by the collisions of heavy-ions with energies of around 100 MeV

Abstract

Nickel and molybdenum specimens were irradiated with 84–120 MeV C, Cl, Br and I ions at temperatures about 150 K. After the irradiation, the development of defect structures was observed by electron microscopy. In molybdenum, the defect clusters introduced by the irradiation are small dislocation loops of vacancy type. The majority of defect clusters in nickel are stacking fault tetrahedra. The number of these defect clusters increases linearly with the ion fluence, whereas the size of the defect clusters do not increase markedly. This implies that each single collision having energy greater than some threshold causes the formation of a defect cluster. The threshold energies for defect clusters production and the surviving probabilities are determined by the results of the present experiments.