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JUNE 26 MONDAY AFTERNOON
RIVA-TF-MoA-OR.14 STUDY OF THE EFFECT OF SILICON EXCESS AND ARTIFI-
CIAL AGEING ON THE MICROSTRUCTURAL STABILITY OF Al-Mg-Si ALLOYS. Y.
Aouabdia*, Boubertakh ABDEL HAMID*, Hamamda SMAÎL*. * Laboratoire des Propriétés Thermodynamiques
et des Traitements de Surface des Matériaux. Faculté des Sciences, Université Mentouri-Constantine
Route Ain El-Bey, 25000 Constantine, Algérie
aouabdiayoucef@yahoo.fr
The use of Al based alloys for automotive body materials has been driven by a number of issues, in
particular weight saving. We are interested in in Al–Mg–Si alloys with excess Si. For this work, we
study the effect of excess Si on the precipitation of the β’’ phase. Samples from an Al–Mg 2 Si–0.5%S
were studied by differential scanning calorimetry (DSC), optical microscopy, Vickers hardness test
ing, and MEB. Data on reaction kinetics, grain size, and micro-hardness are analyzed with reference
to a stoichiometric alloy. This study revealed that excess Si increases the activation energy for the re
action, and globally improves the mechanical properties of the alloy. The precipitation sequence in the
Al-Mg-Si alloys with excess silicon is generally accepted to be:
clusters of solute atoms GP zone IGP zone II/ β” β’ β (Mg 2 Si)+Si
Key words: Al–Mg– Si alloys, excess Si, precipitation, activation energy, β'
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