Annealing process in quenched Al-Sn alloys:: A positron annihilation study -: art. no. 064106

The precipitation of tin atoms and vacancy-tin interaction in the diluted (800 at. ppm) Al-Sn alloy were studied by means of positron-lifetime and coincidence Doppler broadening techniques. In particular, the specimen subjected to the solution treatment at 525 degrees C/2 h finished by the rapid quenching down to room temperature was examined and, furthermore, the stability of the as-quenched microstructure at room temperature was tested. At room temperature we observed Sn atoms bound to quenched-in excess vacancies. Subsequently, the specimen was isochronally annealed up to the temperature of the solution treatment and the processes, which take place when increasing the temperature, were investigated. Among others, we could monitor the Sn nanoclusters' formation that starts at about 130 degrees C. Positron measurements were complemented by calculations of several positron characteristics of Al, Sn, and related defects in order to ensure the consistent interpretation of experimental data.