THE EFFECT OF COLD DEFORMATION AND ANNEALING PHENOMENA ON THE MICROSTRUCTURAL CHANGES AND MICRO-HARDNESS IN Al-Mg-Si ALUMINIUM ALLOYS

Abstract

Aluminium alloys are of particular interest because of their low density, low cost and ease of thermo-mechanical processing. During the recent years, much interest has been shown in the development of alloys with optimal mechanical properties which can be retained at high temperatures. The purpose of the present investigation is to study the microstructure of two Al-Mg-Si alloys containing transition elements after cold deformation 10%, 20 %, 30%, 40% and 50% reduction in thickness and annealing at 1 hour at different temperature by using the optical microscopy, transmission electron microscopic (TEM), Vickers hardness measurement. We notice that the micro-hardness increases with the increasing of the deformation level. The coarse particles, with a particle size of about 2 to 3 µm, give rise to a heavily local deformation of the Aluminium matrix. The formation of well-defined substructure due to the arrangement of dislocations is observed after an increase in annealing temperature.