The aim of the present paper is to investigate the mechanical properties and precipitation behavior of the Al–
4.4Cu–1.5Mg-0.6Mn-0.25Si (wt%) alloy as a function of heat treatment. The X-Ray diffraction analysis (XRD),
Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy
(TEM) and Microhardness Vickers test (HV) have been used to examine the effects of microalloying and the origins of
hardening precipitates during heat treatment. The combined application of these techniques is particularly important in the
study of nanoscale precipitation processes. The solute clusters precede the formation of GP zones or precipitation and have
a defining role on the nature and kinetics of the subsequent precipitation processes. The lower values of the activation
energy of the precipitate particles indicate that, the driving force of the clustering process is low and the Cu addition to this
kind of alloys enhances the clustering process.