電気学会論文誌A(基礎・材料・共通部門誌)
Online ISSN : 1347-5533
Print ISSN : 0385-4205
ISSN-L : 0385-4205
最新号
選択された号の論文の10件中1~10を表示しています
特集:高性能永久磁石材料の開発・応用動向と展望
特集解説論文
  • 竹澤 昌晃
    2025 年 145 巻 7 号 p. 182-187
    発行日: 2025/07/01
    公開日: 2025/07/01
    ジャーナル 認証あり

    High-performance permanent magnets are essential in fields such as industrial machinery, medical equipment, and energy, and demand for them is expected to increase as we move toward carbon neutrality. It is essential to address the issues surrounding the supply of rare earth resources, and there is a need to improve the performance of Nd-Fe-B magnets and develop alternative materials that use less rare earth. In this paper, we review recent trends in the reduction of heavy rare earth elements, optimization of magnet microstructure, evaluation and analysis technology for magnet materials, development of innovative magnet materials, recycling technology for magnet motors, and application fields. Finally, we consider magnet material research’s future direction and role in achieving carbon neutrality.

  • 高木 健太
    2025 年 145 巻 7 号 p. 188-193
    発行日: 2025/07/01
    公開日: 2025/07/01
    ジャーナル 認証あり

    Neodymium magnets (Nd2Fe14B), which are used in the drive motors of electric vehicles, pose high geopolitical risks, so there is active development of alternative magnets in Japan. Sm-Fe compounds have superior intrinsic magnetic properties to Nd2Fe14B compound and are therefore considered to be the leading candidates for the alternative magnets. Sm-Fe compounds are classified into Th2Zn17-type, TbCu7-type, and ThMn12-type based on differences in crystal structure, and have characteristics such as anisotropic magnetic field, saturation magnetization, and Curie temperature that exceed those of Nd2Fe14B compound. However, these Sm-Fe compounds have issues that neodymium magnets do not have, such as difficulty in sintering due to thermal decomposition and the difficulty in synthesizing single crystal powder. Recently, various new metallurgical technologies have been developed to address these issues. For example, Th2Zn17-type Sm2Fe17N3 sintered magnets that do not degrade in magnetic properties have been reported using low-oxygen powder metallurgy and novel liquid phase sintering techniques. Moreover, it was reported that single crystal powder of metastable TbCu7-type Sm-Fe, for which only polycrystalline powder was conventionally available, can be produced by reduction diffusion technique and the thermal plasma technique. In addition, Sm-Fe alloys could not achieve uniaxial anisotropy unless they were nitrided, but nitrogen-free Sm-Fe magnets have currently been invented.

  • 大久保 忠勝
    2025 年 145 巻 7 号 p. 194-199
    発行日: 2025/07/01
    公開日: 2025/07/01
    ジャーナル 認証あり

    We have investigated the mechanism of coercivity evolution in magnets through multi-scale microstructural characterization. Based on these findings, our goal is to enhance the coercivity of heavy rare-earth-lean magnets by optimizing their microstructure. We have developed several new processes and demonstrated improved magnet properties. This review paper describes (1) coercivity enhancement by the eutectic alloy diffusion process, (2) the development of light rare earth magnets, and (3) the development of high electrical resistance magnets. Recently, there has been an increasing demand for highly efficient magnet development that not only improves properties but also meets multiple requirements. Accordingly, (4) data-driven methods are being employed in ongoing magnet development.

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