Magnetic properties and microstructure of high coercivity Zn-bonded Sm-Fe-N magnets
The 10th Pacific Rim International Conference on Advanced Materials and Processing (PRICM10)
Masashi Matsuura, Ryo Matsunami, Nobuki Tezuka, Satoshi Sugimoto (Tohoku Univerisity), Tetsuya Shoji, Noritsugu Sakuma (Toyota Motor Corp, MagHEM)
Abstract
Sm2Fe17N3 has a high saturation magnetization, a large anisotropy field, and a high Curie temperature, however, this compound cannot be sintered because of decomposition above about 600 oC. To obtain high performance Sm-Fe-N bulk magnet, Zn-bonded Sm-Fe-N magnets is expected. Our group prepared Zn-bonded Sm-Fe-N magnets using Zn fine powder with low oxygen content (d50= 0.23 m, oxygen content= 680 ppm), and the low oxygen Zn-bonded Sm-Fe-N magnets showed high coercivity of 2.66 MA/m (15 wt% Zn) [1].
In this study, we investigated relationship between microstructure and coercivity. In magnets without Zn, coercivity decreased and there were -Fe grains at the surface of Sm-Fe-N powder after annealing. However, in high coercive Zn-bonded magnets, Zn-diffused layer existed between the Fe-rich and Sm2Fe17N3 phases after annealing. This indicates that the Zn-diffused layer isolates Sm2Fe17N3 phase from soft magnetic phase (Fe-rich phase), therefore the magnetic isolation can induce high coercivity.
[1]M. Matsuura et al, J. Magn. Magn. Mater., 452 (2018) 243-248.
In this study, we investigated relationship between microstructure and coercivity. In magnets without Zn, coercivity decreased and there were -Fe grains at the surface of Sm-Fe-N powder after annealing. However, in high coercive Zn-bonded magnets, Zn-diffused layer existed between the Fe-rich and Sm2Fe17N3 phases after annealing. This indicates that the Zn-diffused layer isolates Sm2Fe17N3 phase from soft magnetic phase (Fe-rich phase), therefore the magnetic isolation can induce high coercivity.
[1]M. Matsuura et al, J. Magn. Magn. Mater., 452 (2018) 243-248.
その他特記事項
This work was partially supported by the Future Pioneering Program “Development of magnetic material technology for high-efficiency motors” commissioned by the New Energy and Industrial Technology Development (NEDO), Japan, and the Elements Strategy Initiative Center for Magnetic Materials (ESICMM) under the outsourcing project of MEXT, Japan.
