Effects of multiple precipitates on electrical conductivity of aged Al-Mg-Si alloys

The electrical conductivity measurement is a much sensitive tool for studying the precipitation in Al-Mg-Si alloys, but the single effects of solute atoms and fine scale precipitates on electrical conductivity are not clear. In this work, the systematic experiments and modeling were performed to study the effect of multiple precipitates on the electrical conductivity of aged Al-Mg-Si alloys that contain three kinds of precipitates with different compositions and morphologies. The results show that the electrical conductivity of the alloy exhibits the most sensitive to a dominant kind of precipitates, i.e., rod-shaped β″ precipitates at 473 K and needle-shaped β' precipitates at 523 K, respectively. This is because the two kinds of precipitates can form an effective barrier net to hinder the mass migration at 473 and 523 K, respectively. The good agreement between model and experiments indicates the validity of prediction.