Rare earth magnet and method for manufacturing the same
AssigneeSumitomo Special Metals Co., Ltd.
InventorsShigeru Takaki, Ken Makita
Life of this patent
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Abstract
A compact is produced from an alloy powder for R—Fe—B type rare earth magnets including particles having a size in a range of about 2.0 μm to about 5.0 μm as measured by a light scattering method using a Fraunhofer forward scattering in a proportion of approximately 45 vol. % or more and particles having a size larger than about 10 μm in a proportion of less than about 1 vol. %. The compact is then sintered to obtain a R—Fe—B type rare earth magnet having an average crystal grain size in a range of about 5 μm to about 7.5 μm, and an oxygen concentration in a range of about 2.2 at. % to about 3.0 at. %.
Claims16
A method for manufacturing R—Fe—B rare earth magnets, comprising the steps of:
- preparing alloy powder for R—Fe—B rare earth magnets including particles having a size in a range of about 2.0 μm to about 5.0 μm as measured by a light scattering method using a Fraunhofer forward scattering in a proportion of approximately 45 vol. % or more and particles having a size larger than about 10 μm in a proportion of less than approximately 1 vol. %:
- compacting said powder to produce a compact;
- and
- sintering said compact;
- wherein in the step of sintering, a sintered magnet having an average crystal grain size in a range of about 5 μm to about 7.5 μm is produced.
Dependencies are inferred from the claim text.