Abstract

Fabrication and extensive characterization of hard-soft nanocomposites composed of hard magnetic low-temperature phase LTP-MnBi and amorphous Fe70Si10B20 soft magnetic phase for bulk magnets are reported. Samples with compositions Mn55Bi45 + x⋅(Fe70Si10B20) (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 and 57Fe 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.

Details

Title
Microstructure and coupling mechanisms in MnBi–FeSiB nanocomposites obtained by spark plasma sintering
Author
Alexandru-Dinu, A. 1 ; Locovei, C. 1 ; Bartha, C. 2 ; Grigoroscuta, M. A. 2 ; Burdusel, M. 2 ; Kuncser, A. 2 ; Palade, P. 2 ; Schinteie, G. 2 ; Iacob, N. 2 ; Lu, W. 3 ; Batalu, D. 4 ; Badica, P. 2 ; Kuncser, V. 2 

 National Institute of Materials Physics, Magurele, Romania (GRID:grid.443870.c) (ISNI:0000 0004 0542 4064); University of Bucharest, Faculty of Physics, Magurele, Romania (GRID:grid.5100.4) (ISNI:0000 0001 2322 497X) 
 National Institute of Materials Physics, Magurele, Romania (GRID:grid.443870.c) (ISNI:0000 0004 0542 4064) 
 Tongji University, Shanghai Key Laboratory of D&A for Metal-Functional Materials, School of Materials Science and Engineering, Shanghai, China (GRID:grid.24516.34) (ISNI:0000 0001 2370 4535) 
 National University of Science and Technology Politehnica Bucharest, Faculty of Materials Science and Engineering, Bucharest, Romania (GRID:grid.24516.34) 
Pages
17029
Publication year
2024
Publication date
2024
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3083766442
Copyright
© The Author(s) 2024. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.