Nd-Fe-B系焼結磁石における省Dy技術の研究動向

概要

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Nd-Fe-B sintered magnets are widely used in many applications and the motor for hybrid electric vehicles (HEV) becomes one of the promising applications for the magnets. However, as the operating temperature of the magnets becomes over 200°C in the application, a room temperature coercivity around μ0HcJ=3 T is needed. To meet this requirement, currently shipped Nd-Fe-B magnets contain a huge amount of Dy. But, this method has a crucial disadvantage. That is, an estimated short supply of Dy owing to its low natural abundance as compared with that of Nd. In order to realize a high μ0HcJ in Nd-Fe-B magnets without Dy or with a much-reduced Dy content, and to secure a stable future supply of these high-performance magnets, a five year national project has started in Japan. This paper introduces unique researches in the project toward Dy-free or Dy-lean Nd-Fe-B sintered magnets.