[O9] RE Nitrides

9:30 AM - 9:50 AM JST(12:30 AM - 12:50 AM UTC)

[O9-2] Process development of high-performance Sm-Fe-N permanent magnet

*Yusuke Hirayama¹, Shusuke Okada¹, Wataru Yamaguchi¹ (1. National Institute of Advanced Industrial Science and Technology (Japan))

Keywords:

Sm2Fe17N3,powder metallurgy

Sm-based compounds have great potential as permanent magnet compounds. For example, the stable phase Sm₂Fe₁₇N₃ compound^1,2 , the metastable phase TbCu₇-type Fe-rich SmZrFeCoN compound³ , and the non-nitride SmZrFeCoNbB compound⁴ are promising post-neodymium magnets. However, no process has been developed that can fully utilize the potential of any compound. In this presentation, we will focus on the following two compounds and report on the high properties achieved by optimizing the powder synthesis process. Sm₂Fe₁₇N₃ compoundWe are working on improving the process for Sm₂Fe₁₇N₃ single crystal powder using the jet mill and reduction diffusion methods, which are pulverization methods. By optimizing the process parameters in the jet mill process, we have succeeded in synthesizing powder with a much narrower particle size distribution than conventionally obtained powders. The magnetic properties of the powder showed an improvement of more than 7% in both coercivity and remanence. In contrast, the reduction diffusion method had a problem of poor orientation due to strong necking between particles⁵. By properly crushing using a wet jet mill, we succeeded in synthesizing powder with a BHMAX exceeding 370 kJ/m3, which had not been achieved until now. In addition to these powder synthesis process developments, we would like to briefly introduce the sintered Sm₂Fe₁₇N₃ magnet by liquid phase sintered that we have been working on recently. TbCu₇ type Fe-rich Sm-Fe-N compounds Because of a metastable phase, single crystal powder rather than polycrystal is difficult to obtain. At present, processes using low-temperature reduction diffusion⁶ or thermal plasma⁷ have been reported. However, neither process has been able to prepare a Fe-rich compound. Therefore, following the report that achieved Fe-richness by replacing Zr or Y with Sm^3,8, we attempted to synthesize Fe-rich SmZrY-Fe-N compounds using a thermal plasma process. From the XRD measurement results, the peak positions also suggested that the Fe/Sm (at%) ratio was greater than 8.5, so we succeeded in synthesizing Fe-rich SmZrY-Fe-N compound single crystal powder. There is still room for developing permanent magnets using Sm-based compounds, and it is highly significant to continue developing this process. Iriyama, T., et al., Magnetics, IEEE Transactions on (1992) 28 (5), 2326 Coey, J. M. D., et al., Journal of Applied Physics (1991) 69 (5), 3007 Sakurada, S., et al., J. Appl. Phys. (1996) 79 (8), 4611 Kurokawa, N., et al., J. Magn. Magn. Mater. (2022) 556, 169414 Okada, S., et al., Journal of Alloys and Compounds (2023) 960, 170726 Okada, S., and Takagi, K., Journal of Rare Earths (2021) Hirayama, Y., et al., IEEE Transactions on Magnetics (2023) 59 (11), 1 Suzuki, H., AIP Advances (2017) 7 (5), 056208