R-T-B based permanent magnet
AssigneeTDK Corporation
InventorsAtsushi Koda, Takahiro Suwa, Hikaru Kudo
Life of this patent
Estimating the term…
Abstract
An R-T-B permanent magnet that contains: main-phase grains composed of an R2T14B compound (where R is a rare earth element, T is a transition metal element, and B is boron); and grain boundaries. R includes Ce. The R-T-B permanent magnet has a Ce content of 15-35 mass % with respect to the total R content. The grain boundaries include an R-rich phase and an R-T phase. In a cross section of the R-T-B permanent magnet, the surface area ratio S(R-T) of the R-T phases with respect to the grain boundaries is 0.60-0.85.
Claims18
An R-T-B based permanent magnet comprising main phase grains including an R2T14B compound (in which R includes a rare earth element, T includes a transition metal element, and B represents boron), and a grain boundary, wherein
- R at least includes Ce,
- an amount of Ce to a total amount of R in the R-T-B based permanent magnet is within a range of 15 mass % or more and 35 mass % or less,
- an amount of Co is within a range of 0.50 mass % or more and 3.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole,
- the grain boundary includes an R-rich phase and an R-T phase, and
- an area ratio of the R-T phase to the grain boundary in one cross section of the R-T-B based permanent magnet represented by S (R-T) is within a range of 0.60 or larger and 0.85 or smaller.
Dependencies are inferred from the claim text.