Positron Annihilation Studies of Early Stages of Precipitation in Aluminium Alloys

Positron annihilation lifetime and Doppler-broadened annihilation line spectroscopy were used to study precipitation phenomena in various high-strength Al alloys such as Al-Cu, Al-Cu-Mg (2024) and Al-Zn-Mg-Cu (7071). While the positron lifetime is sensitive to vacancy-type defects, the curve shape parameter S of the annihilation line mirrors more the chemical surroundings of the defects and its change during aging of quenched alloys. This allows conclusions on microstructure changes occurring on a microscopic and atomic scale