Permanent magnet alloy having improved resistance to oxidation and process for production thereof
First Claim
1. A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
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Accused Products
Abstract
A permanent magnet made of an R-Fe-B-C or R-Fe-Co-B-C based alloy (where R is at least one rare-earth element) consisting of its individual magnetic crystal grains that are covered with an oxidation-resistant protective film is promising as a practicable next-generation magnet because of its having not only excellent magnetic properties inclusive of magnetic force that surpasses Sm-Co based magnets but also such highly improved oxidation resistance that may withstand use in practical applications for a prolonged time period without being coated on its outermost exposed surface with an oxidation-resistant protective film. Said protective film surrounding the individual magnetic crystal grains contains at least one, preferably substantially all, of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt. %, preferably 0.1-16 wt. % of said protective film being composed of C.
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Citations
32 Claims
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1. A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (10, 11, 12, 13)
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14. A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20%, C up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. In an improved permanent magnet made of a R-Fe-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (29)
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30. In an improved permanent magnet made of a R-Fe-Co-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μ
- m and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
- View Dependent Claims (31, 32)
Specification