R-T-B-based permanent magnet and method for producing same, motor, and automobile
AssigneeTDK Corporation
InventorsYoshinori Fujikawa, Reiji Yamada
Life of this patent
Estimating the term…
Abstract
An R-T-B-based permanent magnet which contains R that represents at least one rare earth element essentially including Tb or Dy, T that represents Fe or at least one iron-group element essentially including Fe and Co, and B that represents boron, and further contains Cu. The total content of R is 28.35 to 29.95% by mass, inclusive, the content of Cu is 0.05 to 0.40% by mass, inclusive, and the content of B is 0.93 to 1.00% by mass, inclusive. The distribution of the concentration of Tb or Dy decreases from the outside of the R-T-B-based permanent magnet toward the inside of the R-T-B-based permanent magnet.
Claims14
An R-T-B based permanent magnet in which R represents one or more rare earth elements which essentially includes Tb or Dy, T represents one or more iron group elements which essentially includes Fe or a combination of Fe and Co, and B represents boron;
- wherein
- the R-T-B based permanent magnet further includes Cu,
- a total content of R is within a range of 28.35 mass % or more and 29.95 mass % or less,
- a content of Cu is within a range of 0.05 mass % or more and 0.40 mass % or less,
- a content of B is within a range of 0.93 mass % or more and 1.00 mass % or less,
- a content of Ga is within a range of 0 mass % or more and 0.05 mass % or less,
- a concentration distribution of Tb or Dy decreases from a surface area towards an inside of the R-T-B based permanent magnet,
- a residual magnetic flux density is 1485 mT or more, the residual magnetic flux density being measured after a grain boundary diffusion process, and
- a coercivity is 1800 kA/m or more.
Dependencies are inferred from the claim text.