Zr–1Nb samples were irradiated with 116 MeV O5+ ions at different doses ranging from 5 × 1017 to 8 × 1018 O5+/m2. X-ray diffraction line profile analysis was performed to characterize the microstructural parameters of these samples. Average domain size, microstrain and dislocation density were estimated as a function of dose. An anomaly was observed in the values of these parameters at a dose of 2 × 1018 O5+/m2. Positron annihilation spectroscopy was used to determine the existence and nature of vacancy clusters in the samples. Isochronal annealing was carried out for a sample to study the evolution of defect clusters.
