This diploma thesis examines the effect of cerium addition on the aluminium alloy EN AW-6082, which belongs to the heat-treatable 6xxx series. The main alloying elements are magnesium and silicon, which enable the formation of the Mg₂Si phase, important for strengthening. The aim of the thesis was to determine how cerium addition affects the phase composition, solidification behaviour, phase transformations and microstructural development of the alloy.
Three samples were compared in the study: a reference sample without cerium addition, and two samples with additions of 0.1 wt.% and 0.2 wt.% Ce. In addition to thermodynamic calculations, the analyses of the samples included simple thermal analysis, differential scanning calorimetry, and metallographic analysis (optical and scanning electron microscopy with EDS).
The results of the thermodynamic calculations showed that cerium in the aluminium matrix forms additional intermetallic phases. In the samples with cerium added, the AlSiCe phase was predominantly observed. It was also found that the addition of cerium did not cause a significant shift in the solidus or liquidus temperatures. Simple thermal analysis and DSC analysis indicated that all samples exhibited similar basic solidification and melting behaviour. In the samples with cerium addition, minor shifts in some characteristic temperatures were observed. Metallographic analysis confirmed the presence of the primary α-Al phase, the Mg2Si eutectic, the α-Al(FeMn)Si eutectic and a quaternary eutectic composed of α-Al(FeMn)Si, β-Al5FeSi and Mg2Si. In the samples with added cerium, an additional polyhedral AlSiCe phase was also present.
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