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Characterization and statistical modeling of the precipitation kinetics in the commercial aluminum alloy AA5182
Precipitation kinetics in the wrought alloy AA5182 during homogenization was investigated by various experimental methods. The constituents generated during casting were identified with energy dispersive X-ray spectroscopy (EDS) analysis. Their volume fraction was measured with optical microscopy. The size evolution of dispersoids during the heat treatment was studied in TEM. The EDS analysis shows that the dispersoids were mainly Al6Mn and α-Al(MnFe)Si. The dispersoids number was counted from a large number of electron back scatter images to yield good statistics. Electrical resistivity measurements were performed to study precipitation indirectly via the solute content. With the above experimental information, the thermodynamics based precipitation model ClaNG was calibrated for the alloy AA5182. Unknown parameters like interface energies of precipitates were adjusted accordingly. ClaNG is capable of describing the simultaneous nucleation, growth and coarsening of all important precipitates in multi-component systems for arbitrary heat treatments. After the unknown parameters were determined, the model was able to predict the volume and size distribution of dispersoids and the matrix composition for varied heat treatments. The predictions were used to design and optimize the heating process with respect to the microstructure of the homogenized ingot.