Irradiation-induced displacement of Ag atoms from lattice sites in an Al-0.2% Mg-0.1% Ag crystal

In irradiated alloys of Al containing approximately 0.1 at.% Ag, Al-Ag (100) dumbbells are created by the trapping of Al interstitial atoms at Ag solute atoms. The results demonstrate that the addition of 0.2% at.% Mg retards not only the formation of Al-Ag dumbbells during annealing from 30 to 100K but also their annihilation during annealing from 180 to 240K. Al interstitials are released from Mg traps at 100-160K, causing further trapping at Ag atoms. Approximately 70% of the Ag atoms return to lattice sites at approximately 200K (stage III) and the remainder at approximately 260K. These results favour migration of Al-Ag dumbbells rather than vacancies during stage III annealing.