EP0197712B1
Expired / Lapsed
EP
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Rare earth-iron-boron-based permanent magnet
Assignee: Toshiba Corp
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Filing: 1986-03-26
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Granted: 1990-01-24
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Expires: 2006-03-26
Abstract
No abstract record available.
Inventors
- 👤 Tetsuhiko C/O Patent Division Mizoguchi
- 👤 Isao C/O Patent Division Sakai
- 👤 Koichiro C/O Patent Division Inomata
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 19:07
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/057; H01F1/0571; H01F1/0575; H01F1/0577
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
121 words
A permanent magnet formed of a sintered alloy, comprising at least one element selected from the group consisting of the rare earth metals and yttrium (R), boron, and iron, characterised in that the alloy comprises 10 to 40% by weight of said at least one element, 0.8 to 1.1% by weight of boron, and the balance of iron, and in that said sintered alloy comprises 2.5% to 5% by volume of an R-rich phase, less than 1% by volume of a B-rich phase, and a balance of up to 100% by volume of a ferromagnetic Fe-rich phase as the main phase, said permanent magnet having a maximum energy product (BH max ) of at least 38.0 MGOe (302 KJ/m 3 ).
Claim 2
Dependent Claim
121 words
A permanent magnet formed of a sintered alloy, comprising at least one element selected from the group consisting of the rare earth metals and yttrium (R), boron, and iron, characterised in that the alloy comprises 10 to 40% by weight of said at least one element, 0.8 to 1.1% by weight of boron, and the balance of iron, and in that said sintered alloy comprises 2.5% to 5% by volume of an R-rich phase, less than 1% by volume of a B-rich phase, and a balance of up to 100% by volume of a ferromagnetic Fe-rich phase as the main phase, said permanent magnet having a maximum energy product (BH max ) of at least 38.0 MGOe (302 KJ/m 3 ).
Claim 3
Dependent Claim
21 words
A permanent magnet according to claim 1, wherein the oxygen content of the alloy ranges from 0.005 to 0.03% by weight.
Claim 4
Dependent Claim
20 words
A permanent magnet according to claim 1, wherein the content of the B-rich phase is less than 0.5% by volume.
Claim 5
Dependent Claim
18 words
A permanent magnet according to claim 1, wherein said element comprises more than 70% by weight of Nd.
Claim 6
Dependent Claim
23 words
A permanent magnet according to claim 1, wherein the Fe-rich phase is formed of a tetragonal system of Nd 2 Fe 14 B.
Claim 7
Dependent Claim
22 words
A permanent magnet according to claim 1, wherein said B-rich phase consists of the alloy Nd 2 Fe 7 B 6 .
Claim 8
Dependent Claim
19 words
A permanent magnet according to claim 1, characterised in that R contains more than 70% by weight of Nd.
Claim 9
Dependent Claim
23 words
A permanent magnet according to claim 1, wherein a portion of the Fe content is replaced by Co, AI or Co + Al.
Claim 10
Dependent Claim
39 words
A permanent magnet according to claim 8, wherein the content of Co is 1 to 20% by weight and the content of AI is 0.4 to 2% by weight (as measured on the basis of the content of Fe).
Claim 11
Dependent Claim
19 words
A permanent magnet according to claim 1, characterised in that R contains more than 70% by weight of Pr.
Claim 12
Dependent Claim
20 words
A permanent magnet according to claim 1, characterised in that the R-rich phase contains more than 90 atm.% of R.
Claim 13
Dependent Claim
27 words
A permanent magnet according to claim 1, characterised in that less than 80 atm.% of the boron content is replaced by C, N, Si, P or Ge.
References Cited (Backward Citations)
No citation records indexed.
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