GP zone formation without quenched-in vacancies in Al–12 wt% Mg alloy

Dissolution of GP zones, formed in aged Al–12?wt%?Mg alloy at ?15 and 24°C, occurs during primary dilatometric and calorimetric tests, but the effect disappears after secondary tests, at low heating and cooling rates (1–2°C/min). After a?new holding at the above temperatures, GP zones again form and β and β′ phases precipitate. The results suggest the formation of GP zones without the presence of quenched-in vacancies.