Study of vacancy clustering in e-irradiated copper by small-angle X-ray scattering

Abstract

The small-angle scattering (SAS) from single vacancies and vacancy clusters in Cu has been observed using a position-sensitive detector system in combination with a high-power (100 kW) rotating-anode X-ray source. The single vacancies were produced at 4 K by irradiation with 3 MeV electrons, and the annealing of the SAS patterns (measured at 4 K) was studied. The experimental results were compared with calculated patterns based on atomistic models for vacancies and vacancy clusters with appropriate corrections for lattice displacements as well as interstitial scattering, For annealing temperatures below 200 K, the SAS patterns corresponded to the expected scattering for single vacancies. Above 200 K, changes in the patterns consistent with the nucleation of small vacancy clusters were observed. These clusters had room-temperature radii of about 7 Å.