高性能ラジアル異方性Nd-Fe-B磁石

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High Performance Radially-Oriented Nd-Fe-B Magnet Takahiko Iriyama, Norio Yoshikawa, Hiyoshi Yamada, Yasuaki Kasai Radially-oriented Nd-Fe-B magnets with (B H)max of 29 ~ 37 MGOe have been produced by hot extrusion of isotropic fully dense magnets made from melt spun powder. The key factors which enhance the (B H)max are the volume fraction and the orientation of magnetic phase (Nd 2 Fe 14 B phase). The orientation of Nd 2 Fe 14 B crystals, which occurs during the hot extrusion, depends on the hot workability of the material. Therefore, in addition to the magnetic properties, the hot workability has been investigated in the material with the composition of 29.0 ~ 32.0 wt% Nd-0.82 ~ 1.03 wt% B-balance Fe-6 wt% Co-0.6 wt% Ga in order to develop the higher (B H)max magnet. The following results were obtained: 1. A good hot workability was observed in the wide composition range except for the composition range of Nd < 30 wt% and B > 0.95 wt%. 2. A (B H ) m a x over 40 MGOe was obtained for the magnet with the composition of 29.0 ~ 29.8 wt% Nd- 0.90 ~ 0.95 wt% B-balance Fe-6 wt% Co- 0.6 wt% Ga by hot extrusion at 800 °C. 3. The newly developed radially-oriented magnet (ND-39R) had the comparable thermal-coefficients of B r and i H c to the conventional magnets (ND-35R and ND-31HR), and its excellent practical property for motors was also confirmed by flux-density evaluation with the sample magnetized
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