Vacancy-Solute Aggregates in Al-Zn-Mg-(Cu, Ag)

R. FERRAGUT; A. DUPASQUIER; M.M. IGLESIAS; C.E. MACCHI; A. SOMOZA; I.J. POLMEAR

MATERIALS SCIENCE FORUM

Trans Tech Publications

Año: 2006 vol. 519 p. 309 - 314

0255-5476

Abstract. Positron annihilation spectroscopy in two versions (lifetime and coincidence Dopplerbroadening) has been applied to investigate solute/vacancy interactions when minor amounts(<1wt.%) of Ag or Cu are added to the alloy Al-4Zn-3Mg (wt.%) during ageing at 150°C. Theresults show early clustering of vacancies with Zn (and with Cu, if present). Ag displays a stronginteraction with vacancies in competition with Mg and forms clusters that may help furtheraggregation of the other alloying elements during artificial ageing. High Mg concentration isobserved at the misfit interfaces of semi-coherent or incoherent precipitates