In this master thesis we present the study of magnetism of high-entropy alloy FeCo-NiPdCu. First we introduce general properties of high-entropy alloys. Afterwards we explain some important magnetic concepts and then briefly describe the influence of electrical resistivity on magnet performance in magnetic applications. Later on we list measurement devices and experimental methods used for experiments. Among them the main are X-ray diffraction, used for crystal lattice determination, electron mi-croscopy for micro- and nanostructure specification, temperature dependent magnet-ization measurement for Curie temperature evaluation and magnetization hysteresis loops measurements for depicting coercivity and saturation magnetization values in high magnetic field. Magnetic measurements and the measurement of electrical resis-tivity were performed also with a non-oriented electrical steel, which is a commercial soft magnet used in electromotor stators and in the cores of transformers. This mas-ter thesis includes the main experimental results. From the analysis of structural measurements it is evident that the FeCoNiPdCu material is a composite of nanostructures that are from two to five nanometers in size. Nanostructures have two different compositional phases, FeCoNi and PdCu phase that are intermixed completely randomly. These nanostructures form due to energetically favorable mix-ing of specific pairs of elements which is explained by their binary mixing enthalpies. On one hand, FeCoNi phase consists of magnetic elements iron, cobalt and nickel which contributes to magnetic behavior of these nanostructures. Not only that, these structures are so small that all consisting atomic magnetic moments are aligned and nanostructures form magnetic domains. On the other hand, PdCu phase consist of non-magnetic palladium and copper atoms. Due to the nano-size of nanostructures an exchange coupling between the atoms causes the effect of averaging exchange anisotropy. This causes coercivity of the material to be near-zero, which we also con-firmed with the magnetic measurements. From the measurement analysis we can conclude that the cause for soft magnetic properties of FeCoNiPdCu lies in the na-noscale magnetism effects. We also compared its magnetic properties to other soft magnetic materials, e.g. non-oriented electrical steel, and concluded that its soft magnetic properties are in the same range as for other materials. Results of experi-mental work offer a new understanding of high-entropy alloy FeCoNiPdCu and could contribute to deeper understanding of magnetism of high-entropy alloys in general.
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