Aluminium alloys have a wide range of applications and they are becoming more commonly used, because they have very good mechanical properties. The aluminium alloys can be divided into casting and wrought alloys, which are further divided into alloys which can be heat treated and non-heat treated. Alloys can also be divided according to the alloying elements used in the alloy itself.
Aluminium alloys in Group 2xxx contain as the main alloying element 2 to 6 wt. % of copper. This increases the strength and workability of the alloy, but also reduces corrosion resistance and weldability. At casting a non-equilibrium solidification occurs. Therefore, the cooled alloy needs to be heat treated, which is called homogenization. Homogenization allows to eliminate crystalline segregations and low-melting eutectics, but also causes changes in the forms of intermetallic phases. Deformation ability is in this way increased.
In diploma work the subject of investigations was the aluminium alloy with designation EN AW 2011 (AlCuBiPb), whereas the comparative analysis before and after homogenization annealing was made. Homogenization was made at 520 °C for 6 h. First a slice from two rods before and after homogenization was cut out, then three samples from each slice of the rod, namely in the middle, on D/4 and at the edge of the slice was prepared. Differential scanning calorimetry (DSC) was performed on all six samples, whereas the results were compared with each other. Samples for optical microscopy and scanning electron microscopy (SEM) were also prepared, whereas phase and chemical composition was analysed. Using Thermo-Calc program, an equilibrium phase diagram, a cooling curve of the alloy and the phase formation during solidification was examined. From obtained results, it was found that the homogenization was carried out successfully, due to a fairly homogeneous chemical composition throughout the cross-section.
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