Development of anisotropic Sm-Fe-Mn-N magnet powder by controlling the rotation of nano-cell structrue

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K18246
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Material processing/Microstructural control engineering
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Hosokawa Akihide 国立研究開発法人産業技術総合研究所, 磁性粉末冶金研究センター, 研究員 (10748461)
• Research Collaborator: TAKAGI Ketna 国立研究開発法人産業技術総合研究所, 磁性粉末冶金研究センター, チームリーダー
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 永久磁石 / 窒化 / TEM / SEM / EBSD / 集合組織

Outline of Final Research Achievements

It is known that the refinement of particle size is effective in improving coercivity of Sm-Fe-N magnet powder. By contrast, it is also known that high coercivity can be obtained by overnitridation that introduces a unique microstructure made of amorphous and nanocrystalline cells. This highly coercive magnet powder unfortunately becomes isotropic and exhibits poor squareness, which has been ascribed to the random crystallographic orientations of the cells. In this study, detailed multi-scale electron microscopy was peformed to clarify the formation mechanism of those fine microstructure. The results demonstrated that the mcirostructure inside a particle is highly heterogeneous, and that the orientations of the nanocrystalline cells are aligned meaning that the statement that the cells rotate during overnitridation seems to be wrong. To improve the property and squareness, it would be effective to improve the homogeneity in microstructure inside the individual overnitrided particles.

Free Research Field

組織制御