Abstract:
The work undertaken in this thesis is reserved for the study of aluminium alloys of different shapes. We are interested in the role of thickness on the different mechanical, spectroscopic, thermodynamic and structural properties. The materials that were the subject of this thesis are the four AlMgSi alloys in the form of sheets obtained by rapid cooling containing several addition elements and two nanocomposites Al + 0.1%NTCM and Al + 1%NTCM. Concerning the sheets, an analysis of the different thermomechanical treatments was carried out using several investigation techniques. For the study of the coefficient of thermal expansion as a function of temperature, it was necessary to take three samples from each sheet in the directions X parallel to the rolling direction; Y perpendicular to the rolling direction and Z perpendicular to the rolling plane. For the purpose of this work, the characterization techniques are differential scanning calorimetry (DSC), thermogravimetry, dilatometry, optical microscopy, X-ray diffraction, microhardness, X-ray diffraction, Raman spectroscopy and infrared spectroscopy. The results of the DSC and dilatometry confirm the precipitation sequences in AlMgSi alloys and show the presence of anomalies whose shapes and intensities vary with temperature. In general, the behaviour is similar to that of conventional aluminium alloys, whose precipitation sequences are well studied. The presence of anisotropy is demonstrated by dilatometry.
Microhardness increases as thickness decreases. The X-ray diffraction study revealed only the presence of the aluminum matrix. The results for the ribbons obtained by DRX showed the presence of alumina and aluminium carbide. Thermogravimetry of nanocomposite reveals a low weight loss compared to pure aluminum Raman spectroscopy revealed the presence of two bands: the D band at 1300cm-1 connected to the disorder while the G band at 1590cm-1 represents the vibration of the sp2 sites. Infrared spectroscopy shows the presence of six peaks: Peak at 3746cm-1 is bound to the hydroxyl group (O-H) ; peak at 2341cm-1 is bound to the hydrogen bond due to oxygen-containing groups (CH...O) ; peak at 2358 cm-1 is bound to CO2 ; peak at 1651 cm-1 is bound to carboxyl functions ; peak at 1047 cm-1 is bound to the C-O bond and peak at 668 cm-1 is bound to aluminum oxide ( Al2O3).
