Effect of Nature Aging on Positron Lifetime Spectroscopy in Casting and Wrought Al-alloys

Abstract

Positron annihilation has been performed in order to study the isochronal annealing of wrought (2024, 7075) and cast (AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) aluminum alloys, at temperatures ranging from RT to 773K, after having been deformed at RT to 25% deformation. Two annealing stages of the microstructures were distinguished, which were attributed to recovery in (2024, AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) due to point defects and dislocations, respectively, and only one (due to dislocations) in (7075). Also, natural aging for up to more than 650 days was studied as a function of mean lifetime.