Etude Calorimétrique d’un alliage d’Aluminium de la sérié 6xxx à excès de Silicium

Abstract

In the various sectors of industry; such as construction; automobile, aeronautics, etc., the Al-Mg-Si alloys of the 6xxx series are the most frequently used. Scientists and researchers are usually performing various heat treatment processes on materials and alloys to meet different requirements for different practical applications. This work is a calorimetric and thermal study of an Al-Mg-Si alloy of the 6xxx series with excess silicon. In this regard, we used two investigation methods: differential scanning calorimetry (DSC) and optical microscopy (OM). The various peaks, which appeared on the DSC curves, were characterized to identify phase transformation processes (precipitation or dissolution of different metastable phases). The maximum of certain peaks obtained on the DSC curve are used to estimate the values of the activation energies. The results obtained show that the kinetic parameters of precipitation of the transformation process significantly vary from one phase to another. The lowering of the heating rate accelerates the precipitation sequence in the Al-Mg-Si alloy. This sequence is described as follows: the G.P zones →  ’’ →  ’ →  (Mg2Si). For their formation, the intermediate phases '', ' and the stable phase , require activation energies of approximately 41 KJ/mol, 60 KJ/mol and 48 KJ/mol, respectively. The homogenization treatment of the studied alloy promotes the release of particles in the aluminum matrix, and the artificial aging treatment at 300°C promotes the reduction in grain size.