Amin Salehi Mobarakeh - Department of Mining and Metallurgical Engineering, Yazd University, Yazd, P.O. Box: 89195-741, Iran
Alireza Mashreghi - Department of Mining and Metallurgical Engineering, Yazd University, Yazd, P.O. Box: 89195-741, Iran
Masoud Mosalayipur - Department of Mining and Metallurgical Engineering, Yazd University, Yazd, P.O. Box: 89195-741, Iran

The cold worked aluminum alloys containing Mg and Cu as the major solutes are strengthened by precipitation of the metastable precursors of the equilibrium β (MgCu) phase in one or more sequences. There are several metastable particles that can form during ageing, but the strengthening potential of these particles relative to one another is not extensively studied. In this paper, the precipitation and hardening potential of different metastable precursors in an Al–0.41%Mg–4.12%Cu–0.50%Fe (wt.%) alloy is studied with the help of differential scanning calorimetry (DSC) and differential thermal analysis (DTA). It has been found that the hardness increase in a freshly solutionized alloy during artificial ageing the T6, 2024 Al alloy showed double-peak age strengthening behavior due to precipitation of clusters and zones. In fact after ageing for 120 min, the samples reached the first peak strength with quite low ductility. However, simultaneous high strength and ductility were achieved by prolonged ageing of 360 min.The particles formed following β'' phase are not effective hardeners

aluminum alloys, precipitation, hardening, ageing ''