Rare earth magnet powder and method of producing the same

  • US 7,632,360 B2
  • Filed: 05/13/2004
  • Issued: 12/15/2009
  • Est. Priority Date: 08/27/2003
  • Status: Expired due to Fees
First Claim
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1. A rare earth magnet powder comprising:

  • a chemical composition comprising R;

    5 to 20 atom % (wherein R represents one, or two or more rare earth elements being inclusive of Y but exclusive of Dy and Tb), one or both of Dy and Tb;

    0.01 to 10 atom %, and B;

    3 to 20 atom %, with the balance comprising Fe and inevitable impurities, an average particle diameter being 10 to 1,000 μ

    m, wherein70% or more of the entire surface of the rare earth magnet powder is covered with a Dy—

    Tb rich layer being rich in content of the one or both of Dy and Tb and having a thickness of 0.05 to 50 μ

    m, anda concentration of the one or both of Dy and Tb in the Dy—

    Tb rich layer is such that the maximum detected intensity of the one or both of Dy and Tb, as measured by wavelength dispersive X-ray spectroscopy, is 1.2 to 5 times the average detected intensity in the central portion being present in the range of ⅓

    of the particle diameter of a particle of the rare earth magnet powder.

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