Investigation of point defects and their agglomerates in irradiated metals by diffuse X-ray scattering

Various experimental techniques for measuring the diffuse scattering intensity over all regions in reciprocal space are reviewed. With these techniques, we obtain information about point defects in the entire size range, starting from the single interstitials and vacancies up to defect clusters, that are large enough to be observed by the electron microscope. The power of these techniques is demonstrated with recent results on aluminum and copper. Defect configurations obtained after low temperature electron irradiation, neutron irradiation, and after annealing at different temperatures are compared. These results resolve many of the long-standing questions in the interpretation of radiation damage and thermal annealing. The -split interstitial is shown to be the stable interstitial configuration after low-temperature irradiation in Al, and very probably also in Cu. During the free migration of the interstitials at the end of recovery stage I, stable interstitial clusters are formed. These clusters grow throughout recovery stage II. In agreement with the observations in the electron microscope, the clusters form dislocation loops on {111} or {110} planes. In copper, there is strong indication for vacancy clustering during recovery stage III. All observations are in good agreement with the 1-interstitial recovery model.