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2024-11-24 21:13

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Conference: Bucharest University Faculty of Physics 2024 Meeting

Section: Solid State Physics and Materials Science

Title:

Coupling mechanisms in MnBi-FeSiB nanocomposites obtained by spark plasma sintering

Authors:

Andrei Alexandru-Dinu (1,2), Petre Badica (1), Victor Kuncser (1)

^*
Affiliation:

1)National Institute of Materials Physics, Atomistilor str. 405 A,Magurele, Romania

2)Faculty of Physics, University of Bucharest, Str. Atomistilor, nr. 405,

Magurele, Romania

E-mail

andrei.alexandrudinu@infim.ro

Keywords:

exchange-spring; RE-free permanent magnets; nanocomposites

Abstract:

This study focuses on the development of RE-free permanent magnets, particularly Mn-based ones, with MnBi as a key compound due to its high magneto-crystalline anisotropy and positive temperature coefficient of coercivity [1,2]. The research proposes composites of MnBi-FeSiB, aiming to understand the intricate relationship between microstructural details and magnetic exchange coupling to achieve exchange-spring magnets [3]. These nanocomposites, comprising hard (MnBi) and soft (FeSiB) magnetic phases with strong exchange interactions, offer promising paths for advanced permanent magnet applications, allowing for enhanced maximum energy products ((BH)max) and novel functional characteristics compared to individual constituents [4,5]. Samples with varying compositions (Mn55Bi45 + x∙Fe70Si10B20, where x = 0, 3, 5, 10, 20 wt. %) were prepared via spark plasma sintering (SPS). Comprehensive characterization techniques, including X-ray diffraction, electron microscopy, magnetometry, and Mössbauer spectroscopy, were employed. The study revealed complex correlations between starting compositions, fabrication processes, and functional magnetic characteristics, uncovering unexpected relations between microstructure and magnetic coupling mechanisms. Exchange spring effects were observed, displaying sensitivity to morpho-structural and compositional features controlled by processing conditions. Overall, the results are showing the potential of powder metallurgy routes combined with SPS in designing and optimizing permanent magnet materials. This research paves the way for the development of tunable magnetic properties in bulk magnets, offering alternatives to rare-earth-based equivalents for various applications.

References:

[1] Yang, J. B. et al., Anisotropic nanocrystalline MnBi with high coercivity at high temperature. Appl. Phys. Lett. 99 (8): 082505. (2011).

[2] Yang, Y.B. et al. Temperature dependences of structure and coercivity for melt-spun MnBi compound. Journal of Magnetism and Magnetic Materials, Volume 330. pp. 106-110. (2013).

[3] Park, K., Hirayama, Y., Yamaguci, W., Kobashi, M., Takagi, K. Exchange-Coupled SmCo5/Fe Nanocomposite Magnet Prepared by Low Oxygen Powder Metallurgy Process. IEEE Transactions on Magnetics 58(2). pp. 1-5. (2022)

[4] Li, X., Pan, D., Xiang, Z., Lu, W., Batalu, D. Microstructure and Magnetic Properties of Mn55Bi55 Powders Obtained by Different Ball Milling Processes. Metals. 9(4). 441. (2019).

[5] Yue, S. Magnetic and thermal stabilities of FeSiB eutectic amorphous alloys: Compositional effects. Journal of Alloys and Compounds. 776. pp. 833-838. (2019).

Acknowledgement:

Authors acknowledge financial support from UEFISCDI, Romania through Core project PC2 PN23080202 and through the grant PN-III-P2-2.1-PED-2021-2007 (contract no. 676 PED/2022).