Positron lifetime and Moessbauer spectroscopy study of vacancy-tin interaction in dilute Al-Sn alloys

Vacancy-tin interaction is studied in dilute Al-Sn alloys quenched from 613 to -70 0C and annealed up to room temperature using parallel positron lifetime and Moessbauer effect measurements. Evidence is found on the formation of small vacancy clusters around tin atoms during the fast quench. The Moessbauer line with an isomer shift of (2.86 ± 0.01) mm/s is identified with these vacancy clusters. Further clustering of isolated vacancies is observed upon isochronal annealing below room temperature. The results also suggest that single vacancies have minor effect on the isomer shift of the line corresponding to tin in solid solution. (author)