Chang, C.S.T.; Liang, Z.; Schmidt, E.; Banhart, J.: Influence of Mg/Si ratio on the clustering kinetics in Al-Mg-Si alloys. International Journal of Materials Research 103 (2012), p. 955-961

The clustering kinetics of Al─Mg─Si alloys is studied by means of differential scanning calorimetry. Five alloys with different Mg and Si contents from 0.4 to 1.1 at.% are used. Two overlapping cluster peaks are observed in the heat flow curves; Cluster 1 (C1) situated at 50 °C and Cluster 2 (C2) situated at around 80 °C when heating at 10 Kmin-1. It was found that the heat effect of clustering is largest in alloys with Mg/Si close to 1, while the C1/C2 heat effect ratio depends on the Si content. Activation energies for the two clustering processes C1 and C2 are obtained by applying different evaluation methods. The alloy having an Mg/Si ratio close to 1 has the smallest initial activation energies for C1, while samples with higher Mg content have lower initial activation energies for C2, inferring that C1 is Si-related, whereas C2 is Mg-related. However, the entire clustering process requires both Mg and Si to proceed.