In this doctoral thesis three groups of quasicrystalline aluminium alloys were developed and synthesized. Synthesis of each alloy was followed by gravitational casting in a copper mould with a shape of a tensile-test specimen with diameter of 5,5 mm. Development of the alloys involved known effects of beryllium and silicon on the increased forming ability of Mackay-type icosahedral quasicrystalline phase (iQC-phase) in the Al-Mn(-Cu) system during casting into a copper mould. Alloys’ microstructural characterization was performed via several observing techniques with respect to their average chemical composition. Mechanical properties of the individual alloy were obtained mainly through compression testing at room temperature, 300 and 400 °C. By additional various heat treatments, further potential for improving the mechanical properties of alloys from all three groups was studied. Heat treatment T6 did not increase strength properties in any of the alloys, while the direct artificial aging (T5) at 160 °C or 180 °C did not affect the microstructure and consequently the hardness of the Al-Mn-Be-Cu-alloys. In heat-treated state of the Al-Mn-Be-Cu-Si and Al-Mn-Cu-Si-alloys, the stabilizing effect of silicon on the iQC-alloys was confirmed. Smaller additions of the silicon (0,7–1,2 at. %) had already positive effect, despite possibly lower manganese content in some alloys (less than 2 at. % Mn). During the heat treatment (solutioning at 510 °C) edges of the primary iQC-phase begins to transform, but it’s inner structure remained quasicrystalline. Low additions of the silicon also increased the tendency to the formation of iQC-phase in as-cast state, without the formation of any other primary phases. During the heat treatment of the Al-Mn-Be-Cu alloys, primary iQC-phase gradually transformed to the decagonal quasicrystalline phase and finally into the crystalline phase. On the other hand, the additions of beryllium into the alloys prevented the formation of the hardening precipitates (θ’-Al2Cu) during the heat treatment. Precipitates with a potential hardening effect formed only in the Al-Mn-Cu-Si-alloys, which showed maximum compressive yield strength when comparing all three groups of investigated alloys in T6-state. Considering the microstructure and mechanical properties, it has been found that the presence of iQC-phase increased compressive yield strength, but at the same time reduced the formability at room temperature of all the alloys and at 300 and 400 °C in the case of Al-Mn-Be-Cu and Al-Mn-Be-Cu-Si-alloys. When the strength properties are considered, the alloys in as-cast state are better than in T6-state, the highest compressive yield strength had Al-Mn-Cu-Si-alloy’s sample (247 MPa), whereas the maximum hardness (HV 1 = 120) was achieved in the sample of Al-Mn-Cu-Si-alloy.
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