EP0270934A1
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A method for producing a rare earth metal-iron-boron anisotropic sintered magnet from rapidly-quenched rare earth metal-iron-boron alloy ribbon-like flakes
Assignee: Tokin Corp
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Filing: 1987-11-26
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Granted: —
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Expires: 2007-11-26
Abstract
Abstract In a method for producing a rare earth metal-iron-boron (R-Fe-B) anisotropic sintered magnet from R-Fe-B alloy ribbon-like flakes, each flake is formed with a thickness of about 20-500 µm and contains R₂Fe₁₄B crystal grains dispersed in the flake with an average grain size of 10 µm or less. The flakes are ground into a powder having an average particle size less than the thickness value of the flake. The powder is magnetically aligned and compacted into a compact body which is then sintered. Thus, the anisotropic sintered magnet is obtained with a high energy product and a high anti-corrosion property. The ribbon-like flakes are prepared by the continuous splat-quenching method. Alternatively, the flakes can be prepared by spraying the molten R-Fe-B alloy in a form of particles and cooling the particles on a cooling plate into flat small pieces.
Inventors
- 👤 Tadakuni Sato
- 👤 Yuichi Tachiya
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 05:23
CPC Classifications
B; B22; B22D; B22D11/00; B22D11/06; B22D11/0622; B22D11/0611; B22F; B22F9/00; B22F9/02; B22F9/06; B22F9/08; B22F9/10; 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; H01F1/0578
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
174 words
In a method for producing a rare earth-transition metal-boron (R-T-B) sintered magnet by preparing an R-T-B alloy powder containing R₂T₁₄B crystal grains, putting the powder in a magnetic field and compacting the powder into a compact body of a desired shape, and sintering the compact body at a sintering temperature thereby to produce the sintered magnet, the improvement wherein said R-T-B alloy powder is a rapidly quenched alloy powder produced by: preparing said R-T-B alloy in a molten state; rapidly quenching said molten R-T-B alloy to form ribbons and/or ribbon-like flakes, each ribbon and/or flake having a thickness and containing said crystal grains uniformly dispersed in said ribbon and/or flake, said crystal grains having an average grain size; and crushing and grounding said ribbons and/or flakes into a powder of an average particle size of a value less than said thickness but larger than said average grain size, each particle of said powder containing said crystal grains extending in a direction, to thereby enable said powder to be magnetically aligned in said magnetic field.
Claim 2
Dependent Claim
174 words
In a method for producing a rare earth-transition metal-boron (R-T-B) sintered magnet by preparing an R-T-B alloy powder containing R₂T₁₄B crystal grains, putting the powder in a magnetic field and compacting the powder into a compact body of a desired shape, and sintering the compact body at a sintering temperature thereby to produce the sintered magnet, the improvement wherein said R-T-B alloy powder is a rapidly quenched alloy powder produced by: preparing said R-T-B alloy in a molten state; rapidly quenching said molten R-T-B alloy to form ribbons and/or ribbon-like flakes, each ribbon and/or flake having a thickness and containing said crystal grains uniformly dispersed in said ribbon and/or flake, said crystal grains having an average grain size; and crushing and grounding said ribbons and/or flakes into a powder of an average particle size of a value less than said thickness but larger than said average grain size, each particle of said powder containing said crystal grains extending in a direction, to thereby enable said powder to be magnetically aligned in said magnetic field.
Claim 3
Dependent Claim
31 words
A method as claimed in Claim 1, wherein each of said flakes has a thickness of 20-500 µm, said crystal grains having an average grain size of 10 µm or less.
Claim 4
Dependent Claim
20 words
A method as claimed in Claim 2, wherein each of said ribbons and/or flakes has a thickness of 50-500 µm.
Claim 5
Dependent Claim
19 words
A method as claimed in Claim 2, wherein said crystal grains has an average grain size of 1-10 µm.
Claim 6
Dependent Claim
21 words
A method as claimed in Claim 2, wherein said crushed and ground powder has an average particle size of 0.3-15 µm.
Claim 7
Dependent Claim
21 words
A method as claimed in Claim 5, wherein said crushed and ground powder has an average particle size of 1.5-7 µm.
Claim 8
Dependent Claim
28 words
A method as claimed in Claim 5, wherein said sintering is carried out so that said crystal grains are grown to have a grain size of 7-30 µm.
Claim 9
Dependent Claim
26 words
A method as claimed in Claim 1, wherein said R-T-B alloy powder consists, by weight, of R 28.0-65.0 %, and the balance of T and B.
Claim 10
Dependent Claim
25 words
A method as claimed in Claim 8, wherein said R-T-B alloy powder consists, by weight, of R 30-40%, B 0.8-1.3%, and the balance of T.
Claim 11
Dependent Claim
33 words
A method as claimed in Claim 8, wherein said transition metal elements T in said R-T-B alloy are Fe and Co represented by Fe 1-x Co x , x being 0.35 or less.
Claim 12
Dependent Claim
52 words
A method as claimed in Claim 1, wherein said molten R-T-B alloy is ejected through a small orifice onto an outer peripheral chill surface of a quenching disk rotating at a predetermined speed in said rapidly-quenching step, said ejected molten alloy thereby being rapidly cooled into the rapidly-quenched ribbons and/or ribbon-like flakes.
Claim 13
Dependent Claim
33 words
A method as claimed in Claim 11, wherein a magnetic field is applied in a radial direction of said quenching disk so that said ejected molten alloy is cooled in said magnetic field.
Claim 14
Dependent Claim
52 words
A method as claimed in Claim 11, wherein said quenching disk is provided with a plurality of projections formed in said chilling surface and a cooling plate is disposed adjacent said quenching disk, said molten alloy ejected onto the chilling surface is sprayed onto said cooling plate to form flat ribbon-like flakes.
Claim 15
Dependent Claim
19 words
A method as claimed in Claim 13, wherein each of flat ribbon-like flakes has a thickness of 7-500 µm.
Claim 16
Dependent Claim
36 words
A method as claimed in Claim 1, wherein said molten R-T-B alloy is sprayed and atomized through a spray nozzle onto a cooling plate and rapidly cooled on said cooling plate to form flat ribbon-like flakes.
Claim 17
Dependent Claim
46 words
A method as claimed in Claim 11, wherein after said molten alloy is deposited onto said chilling surface and is rapidly quenched to form a ribbon, an outer surface of said ribbon is rapidly quenched by engagement with another quenching disk to obtain a rapidly-quenched ribbon.
Claim 18
Dependent Claim
17 words
A method as claimed in Claim 16, wherein said rapidly-quenched ribbon has a thickness of 20-1,000 µm.
Claim 19
Dependent Claim
25 words
A method as claimed in Claim 1, wherein said rapidly-quenched ribbons and/or flakes are subjected to a heat treatment at a temperature of 650-950 °C.
References Cited (Backward Citations)
EP0197712B1
Cited
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