R-T-B-based sintered magnet
AssigneeTDK Corporation
InventorsMariko Fujiwara, Masashi Miwa
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Abstract
An R-T-B-based sintered magnet 2 contains a rare earth element R, a transition metal element T, B, Ga, and O, the sintered magnet 2 includes a magnet body 4 and an oxidized layer 6 covering the magnet body 4, the magnet body 4 includes main phase grains 8 containing a crystal of R2T14B and a grain boundary phase 1 positioned between the main phase grains 8 and containing R, the oxidized layer 6 includes a plurality of oxide phases 3A containing R, T, Ga, and O, the oxide phase 3A satisfies the following Formulas (1) and (2) regarding the content (unit: atom %) of each element, and the oxide phase 3A in the oxidized layer 6 covers the grain boundary phase 1 in the magnet body 4. 0.3≤[R]/[T]≤0.5 (1) 0.2≤[O]/([R]+[T]+[Ga]+[O])≤0.7 (2)
Claims5
An R-T-B-based sintered magnet comprising:
- a rare earth element R, a transition metal element T, B, Ga, and O,
- wherein the R-T-B-based sintered magnet contains at least one of Nd and Pr as R,
- the R-T-B-based sintered magnet contains at least Fe of Fe and Co as T,
- the R-T-B-based sintered magnet includes a magnet body and an oxidized layer covering at least a part of the magnet body,
- the magnet body includes:
- a plurality of main phase grains including a crystal of R2T14B, and
- a grain boundary phase positioned between at least two of the plurality of main phase grains and containing R,
- the oxidized layer includes a plurality of oxide phases containing R, T, Ga, and O,
- a content of R in the plurality of oxide phases is [R] atom %,
- a total content of Fe and Co in the plurality of oxide phases is [T] atom %,
- a content of Ga in the plurality of oxide phases is [Ga] atom %, and
- a content of O in the plurality of oxide phases is [O] atom %,
- the plurality of oxide phases satisfy:
- 0.3≤[R]/[T]≤0.5, and
- 0.2≤[O]/([R]+[T]+[Ga]+[O])≤0.7, and
- at least a part of the plurality of oxide phases included in the oxidized layer covers at least a part of the grain boundary phase included in the magnet body.
Dependencies are inferred from the claim text.