Defect clusters and annealing in self-ion-irradiated nickel

Abstract

Transmission electron microscopy and x-ray diffuse scattering have been used to study defect clusters in 4-MeV self-ion-irradiated (total doses of 2.5×1013 and 5.0×1013 ions/cm2) nickel. The distribution of defect clusters as a function of the ion penetration depth was measured directly in the electron microscope using a transverse sectioning technique. For an ion dose of 2.5×1013 cm -2, the average cluster radius of 32±2 Å at the damage peak depth (0.82 μm) was 20% larger than the average radius near the crystal surface. The fraction of point defects created in the displacement cascades that survived in the form of defect clusters was found to be about 1% for these doses. Annealing at 125, 250, and 450°C gave a monotonic decrease in the number of point defects stored in the form of loops.