US5201963A
Expired / Lapsed
US
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Rare earth magnets and method of producing same
Assignee: Nippon Steel Corp
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Filing: 1991-12-04
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Granted: 1993-04-13
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Expires: 2011-12-04
Abstract
Abstract Rare earth magnets comprising 12 to 20 at % R (where R denotes rare earth elements including at least one selected from neodymium and praseodymium) and 2 to 10 at % boron, with the remainder being TM (where TM=Fe1-xCox (0</=x</=0.4)) and unavoidable impurities, wherein 50 to 100 vol % of the magnet is formed of recrystallization grains of R2Fe14B intermetallic compound having a tetragonal crystal structure with an average grain size of 1 to 100 mu m and an induced anisotropy P of 0.1 or more (where P=(Br( PARALLEL )-Br( ORTHOGONAL ))/(Br( PARALLEL )+Br( ORTHOGONAL )), Br( PARALLEL ) being residual magnetic flux density along the easy magnetization axis and Br( ORTHOGONAL ) being residual magnetic flux density perpendicular to the easy magnetization axis), and the method of producing the rare earth magnets.
Inventors
- 👤 Toshio Mukai
- 👤 Tatsuo Fujimoto
- 👤 Toru Inaguma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:26
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; H01F1/0576; B; B22; B22F; B22F3/00; B22F3/12; B22F3/14
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
187 words
A method of producing an anisotropic rare earth magnet, comprising the steps of: rapidly quenching a melt and forming an alloy powder consisting essentially of 12 to 20 at % R (where R denotes rare earth elements including at least one member selected from the group consisting of neodymium and praseodymium), 2 to 10 at % boron, up to 5 at % copper, with the remainder being TM (where TM=Fe 1-x Co x (0≦x≦0.4)) and unavoidable impurities; hot-pressing the alloy powder to form a pressed body by consolidating the powder to 90% or more of the full density of the alloy powder; recrystallization heat treating the pressed body at 750°-1150° C.; and aging the pressed body at 450°-750° C.; wherein the resultant anisotropic rare earth magnet has recrystallization grains of R 2 Fe 14 B intermetallic compound having a tetragonal crystal structure with an average grain size of 1 to 100 μm and an induced anisotropy P of 0.1 or more where P=(Br(∥)-Br(⊥))/(Br(∥)+Br(⊥)), Br(∥) being residual magnetic flux density along the easy magnetization axis and Br(⊥) being residual magnetic flux density perpendicular to the easy magnetization axis.
Claim 2
Independent Claim
187 words
A method of producing an anisotropic rare earth magnet, comprising the steps of: rapidly quenching a melt and forming an alloy powder consisting essentially of 12 to 20 at % R (where R denotes rare earth elements including at least one member selected from the group consisting of neodymium and praseodymium), 2 to 10 at % boron, up to 5 at % copper, with the remainder being TM (where TM=Fe 1-x Co x (0≦x≦0.4)) and unavoidable impurities; hot-pressing the alloy powder to form a pressed body by consolidating the powder to 90% or more of the full density of the alloy powder; recrystallization heat treating the pressed body at 750°-1150° C.; and aging the pressed body at 450°-750° C.; wherein the resultant anisotropic rare earth magnet has recrystallization grains of R 2 Fe 14 B intermetallic compound having a tetragonal crystal structure with an average grain size of 1 to 100 μm and an induced anisotropy P of 0.1 or more where P=(Br(∥)-Br(⊥))/(Br(∥)+Br(⊥)), Br(∥) being residual magnetic flux density along the easy magnetization axis and Br(⊥) being residual magnetic flux density perpendicular to the easy magnetization axis.
Claim 3
Dependent Claim
19 words
The method according to claim 1, wherein up to 20 at % of the total R amount is dysprosium.
Claim 4
Dependent Claim
21 words
The method according to claim 1 in which hot-pressing is effected by passing an electric current through the powder under pressure.
Claim 5
Dependent Claim
21 words
The method according to claim 2 in which hot-pressing is effected by passing an electric current through the powder under pressure.
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