Numerous alloying elements are added to pure aluminum to improve its mechanical properties. Which of the alloying elements we choose depends on the application, the use of the alloy. Copper is added to aluminum to increase the strength and machinability. One of such alloys is the alloy EN AW2011, which in addition to 5.00 - 6.00 wt. % Cu also contains lead and bismuth. As the solidification of alloys in standard industrial practices occurs at higher cooling rates, inhomogeneities, leaks and intermetallic phases, mainly in the form of Al2Cu in alloys of the 2xxx series occur in the microstructure. By homogenization of this series's alloys, we can reduce the proportion of brittle and unbalanced phases and the average size of the Al2Cu phase, dissolve soluble components, and enable a more homogeneous distribution throughout the microstructure.
The main aim of the diploma work was analysis of EN AW2011 alloy homogenization with electrical resistivity measurement. For this purpose, we made cylindrical samples and performed measurements of specific electrical resistance as a function of time in a horizontal tubular resistance electric furnace. For comparative analysis, 12-hour homogenization was conducted at two temperatures: 480 and 520 °C, and DSC analysis was performed.
After the measurements, we made curves of the homogenization course as a function of time. The specific electrical resistivity curves increased markedly in the first 100 minutes and the DSC curves in the first 50 minutes of homogenization annealing at 520 °C, while on the curves of samples homogenized at 480 °C in the first minutes of annealing before rise there was an additional deviation. In the following hours of homogenization, the slope of the curves in the measurements at both temperatures was adjusted. It can be concluded that most of the main processes of EN AW2011 homogenization at a temperature of 520 °C are carried out in the first 100 minutes of homogenization annealing.
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