Identification of nature of dislocation loops grown as vacancy source after up-quenching

The dislocation loops grown as vacancy source after up-quenching in 99.9999 % aluminum single crystals with a low dislocation density were examined by synchrotron topography in order to determine the Burgers vector and the na ture directly. The specimen crystal was heated to 295 degrees C and hold fo r 15min at the temperature, then cooled down to room temperature to freeze the loops in the specimen. Topographs were taken on the high-speed X-ray to pographic station (BL-15B) at the Photon Factory (KEK-PF), White beam topog raphs were taken using four of symmetrically equivalent I Il and 220 reflec tions for the determination of the Burgers vector. Monochromatic section to pographs were also taken dth 111, 222, 333 and 444 reflections at a wavelen gth of 0.62 Angstrom. The image of the loops was simulated by numerical sol ution of the Takagi-Taupin equations. Burgers vector of the frozen loops wa s determined to be a/2[110]. And comparison between the observed loop image and the simulated one showed that the dislocation loop grown as a vacancy source uas interstitial-type and the size ranged from 3 mu m to 10 mu m in radius.