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Name (Title):<br />
Kazuhiro Hono (NIMS Fellow and MANA PI)<br />
Affiliation:<br />
MANA and Magnetic Materials Center<br />
Address:<br />
National Instiute for Materials Science<br />
Email: kazuhiro.hono@nims.go.jp<br />
Home Page: http://www.nims.go.jp/apfim/<br />
Presentation Title:<br />
Toward higher performance permanent magnets for automotive applications<br />
Interests in the coercivity mechanism of Nd-Fe-B based permanent magnets have recently<br />
been revived due to the increasing demand for high coercivity Nd-Fe-B based permanent magnets<br />
for automotive applications. To understand the microstructure-coercivity relationships of Nd-Fe-<br />
B magnets, we have investigated the microstructures of commercial and experimental sintered<br />
magnets and the hydrogen disproportionation desorption recombination (HDDR) powder by high<br />
resolution scanning electron microscopy,<br />
transmission electron microscopy and atom<br />
probe tomography. Continuous thin layers<br />
of a Nd-rich amorphous phase were found<br />
along the grain boundaries of optimally<br />
annealed sintered magnets, whose chemical<br />
composition was determined to be<br />
Fe41Nd33Cu32, suggesting that the Nd2Fe14B<br />
grains are completely enveloped by a Cu<br />
and Nd enriched layer. Although the Ndrich<br />
layer was also observed in the<br />
optimally processed HDDR powder, it was<br />
found to be crystalline with much less Ndenrichment.<br />
Based on the information on<br />
the nanostructure feature of Nd-Fe-B<br />
magnets, we propose what we should do<br />
for developing higher coercivity Nd-Fe-B<br />
based magnets.<br />
References:<br />
1. W. F. Li, T. Ohkubo and K. Hono, Acta Mater (2009) in press.<br />
2. W. F. Li, T. Ohkubo and K. Hono, J. Mater. Res. (2009), in press.<br />
3. W. F. Li, T. Ohkubo, K. Hono, T. Nishiuchi, and S. Hirosawa, Appl. Phys. Lett. 93, 052505<br />
(2008).<br />
This work was supported by TOYOTA, CREST-JST, Rare Metal Substitute Materials<br />
Development Project on "Development of technology for reducing dysprosium usage in a rareearth<br />
magnet", METI, Elements Science and Technology Project for "High performance<br />
anisotropic nanocomposite permanent magnets with low rare-earth content", and MEXT, Japan.<br />
4<br />
Oral Presentation 4
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