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Multicomponent Alloys Based on Immiscible Systems Prepared by Powder Metallurgy Route
Adam, Ondřej ; Svoboda, Jiří (referee) ; Sopoušek, Jiří (referee) ; Jan, Vít (advisor)
Immiscible alloys are a relatively well-known group of materials, however, they are still being intensively studied, especially from the point of view of heterogeneous materials with very good mechanical properties, but also electrical properties, for example. The main part of the research deals with cast materials, although in the case of immiscible alloys, there is a risk of liquid separation, which results in the loss of mechanical properties. This dissertation deals with the study of Cu-Fe-based immiscible alloys prepared by powder metallurgy methods. The theoretical part summarizes basic information about immiscible alloys, their microstructure, properties, and production options. The experimental part is first devoted to the choice of the suitable chemical composition of the studied alloys and subsequently to the optimization and influence of the mechanical alloying parameters on the properties of prepared powders. The main part of the experiments contains a complex structural, phase, and thermal analysis of Cu50Fe50 and Cu50(FeCo)50 alloys. In both alloys, a dual-phase ultrafine-grained microstructure was formed after sintering. The most significant of the presented results is the excellent resistance to grain coarsening compared to the other ultrafine-grained materials, where even after sintering at very high temperatures, the average grain size remained below 1 micron. The presumed reason is the immiscible nature of the studied alloys.
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