Influence of Mg/Si ratio on the clustering kinetics in Al–Mg–Si alloys

Abstract

Abstract The clustering kinetics of Al–Mg–Si alloys are 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 K min−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.