Investigation of the Effect of Addition of Si and Cu on Al-Mg-Si Alloy

The present work is an investigation of the effect of addition of Si and Cu on the precipitation sequence in Al-Mg-Si Alloys. For this purpose, four Al alloys namely, Al-1.1 wt%Mg2Si (balanced), Al-1.12 wt% Mg2Si-0.35 wt % Si (excess Si), Al-1.07 wt% Mg2Si-0.33 wt% Cu (balanced + Cu) and Al-1.1 wt% Mg2Si-0.36 wt% Si-0.34 wt% Cu (excess Si + Cu) have been considered. Microhardness (HV), differential scanning calorimetry (DSC), electrical resistivity and thermoelectric power (TEP) measurements have been carried out for this study. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD), examinations have been utilized to confirm the obtained results. It was found that the excess Si enhances the precipitation kinetics and improves the strength of the material. On the other hand, addition of Cu induced formation of the Q`- phase which has a positive contribution to the alloy strength.