Muon Spin Relaxation and Positron Annihilation Spectroscopy Studies of Natural Aging in Al-Mg-Si Alloys

Abstract

Muon spin relaxation (µSR) is sensitive to magnetic fields from atomic nuclei, making it suitable for studying vacancies and solute clustering inside aluminium alloys. Positron annihilation spectroscopy (PAS) gives complimentary information about the electron density. We have conducted µSR and PAS experiments on an Al alloy with 1.07 at.% Mg and 0.53 at.% Si during natural aging after solution heat treatment. Three stages of positron lifetime change are visible, while the muon depolarization shows a decrease through the first two of these. This is explained on the basis of vacancy migration, vacancy–solute binding and solute clustering.