1. Microstructure and coupling mechanisms in MnBi-FeSiB nanocomposites obtained by spark plasma sintering.
- Author
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Alexandru-Dinu A, Locovei C, Bartha C, Grigoroscuta MA, Burdusel M, Kuncser A, Palade P, Schinteie G, Iacob N, Lu W, Batalu D, Badica P, and Kuncser V
- Abstract
Fabrication and extensive characterization of hard-soft nanocomposites composed of hard magnetic low-temperature phase LTP-MnBi and amorphous Fe
70 Si10 B20 soft magnetic phase for bulk magnets are reported. Samples with compositions Mn55 Bi45 + x⋅(Fe70 Si10 B20 ) (x = 0, 3, 5, 10, 20 wt.%) were prepared by spark plasma sintering of powder mixtures. Characterization has been performed by X-ray diffraction, scanning and transmission electron microscopy, magnetometry and57 Fe Mӧssbauer spectroscopy. It was shown that samples contain crystallized and nanometric LTP-MnBi phases with various elemental compositions depending on the degree of Bi clustering. Complex correlations between starting compositions, processes during fabrication, and functional magnetic characteristics were observed. Unexpected special situations of the relation between microstructure and magnetic coupling mechanisms are discovered. Exchange spring effects of different strengths occur, being very sensitive to morpho-structural and compositional features, which in turn are controlled by processing conditions. An in-depth analysis of related microscopic characteristics is provided. Results of this work suggest that fabrication by powder metallurgy routes, such as spark plasma sintering of hard and soft magnetic powder mixtures, of MnBi-based composites with exchange spring phenomena have a high potential in designing and optimization of suitable materials with tunable magnetic properties towards rare-earth-free permanent magnet applications., (© 2024. The Author(s).)- Published
- 2024
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