Claims
- 1. A permanent magnet formed of a sintered alloy, comprising:
- (i) 10 to 40% by weight of at least one metal element selected from the group consisting of the rare earth elements (R) and yttrium, (ii) 0.8 to 1.1% by weight boron and (iii) the balance iron, wherein said sintered alloy consists essentially of a ferromagnetic Fe-rich phase as the main phase, 2.5 to 5.0% by volume of a R-rich phase and less than 1% by volume of a B-rich phase, said alloy having a maximum energy product (BH.sub.max) of at least 38.0 MGOe.
- 2. The permanent magnet according to claim 1, wherein the oxygen content of the alloy ranges between 0.005 and 0.03% by weight.
- 3. The permanent magnet according to claim 17, wherein said B-rich phase consists of the alloy Nd.sub.2 Fe.sub.7 B.sub.6.
- 4. The permanent magnet according to claim 1, wherein the content of the B-rich phase is less than 0.5 vol. %.
- 5. The permanent magnet according to claim 1, wherein R represents Nd.
- 6. The permanent magnet according to claim 1, wherein R contains more than 70% by weight of Nd.
- 7. The permanent magnet according to claim 1, wherein R represents Pr.
- 8. The permanent magnet according to claim 1, wherein R contains more than 70% by weight of Pr.
- 9. The permanent magnet according to claim 1, wherein the Fe-rich phase is formed of a tetragonal system of Nd.sub.2 Fe.sub.14 B.
- 10. The permanent magnet according to claim 1, wherein the R-rich phase contains more than 90 atm. % of R.
- 11. The permanent magnet according to claim 1, wherein less than 80 atm. % of the boron content is replaced by C, N, Si, P, or Ge.
- 12. The permanent magnet according to claim 1, wherein part of the Fe content is replaced by Co, Al or Co+Al.
- 13. The permanent magnet according to claim 12, wherein the content of Co is 1 to 20% by weight and the content of Al is 0.4 to 2% by weight (as measured on the basis of the content of Fe).
- 14. A permanent magnet formed of a sintered alloy, comprising:
- 10 to 40% by weight of at least one element selected from the group consisting of the rare earth metals (R) and yttrium, 0.8 to 1.1% by weight boron and with the balance being iron, wherein said sintered alloy comprises at least 96.5% by volume of a ferromagnetic Fe-rich phase as the main phase, at least 2.5% by volume of a R-rich phase and less than 1% by volume of a B-rich phase, said permanent magnet having a maximum product (BH.sub.max) of at least 38.0 MGOe.
- 15. The permanent magnet according to claim 14, wherein the oxygen content of the alloy ranges from 0.005 to 0.03% by weight.
- 16. The permanent magnet according to claim 14, wherein the content of the B-rich phase is less than 0.5% by volume.
- 17. The permanent magnet according to claim 14, wherein said element comprises more than 70% by weight of Nd.
- 18. The permanent magnet according to claim 14, wherein the Fe-rich phase is formed of a tetragonal system of Nd.sub.2 Fe.sub.14 B.
- 19. The permanent magnet according to claim 14, wherein a portion of the Fe content is replaced by Co, Al or Co+Al.
- 20. The permanent magnet according to claim 19, wherein the content of Co is 1 to 20% by weight and the content of Al is 0.4 to 2% by weight (as measured on the basis of the content of Fe).
- 21. A permanent magnet having a maximum energy product (BH.sub.max) of at least 38.0 MGOe, comprising at least 96.5% by volume of a ferromagnetic Fe-rich phase as the main phase, at least 2.5% by volume of an R-rich phase and less than 1% by volume of a B-rich phase, manufactured by a process comprising the steps of:
- (i) preparing an alloy consisting essentially of about 10-40% by weight of R, about 0.8 to 1.1% by weight of boron with the balance being iron, wherein R is at least one element selected from the group consisting of yttrium and the rare earth elements;
- (ii) pulverizing the alloy into a powder;
- (iii) molding said powder in a magnetic field thereby obtaining a molded mass; and
- (iv) sintering the molded mass at a temperature of about 1000.degree.-1200.degree. C. in an atmosphere of 5.times.10.sup.-1 Torr or less to obtain said permanent magnet.
Priority Claims (1)
Number |
Date |
Country |
Kind |
60-61837 |
Mar 1985 |
JPX |
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Parent Case Info
This application is a continuation of abandoned application Ser. No. 07/142,356, filed Dec. 28, 1987 which in turn is a continuation of abandoned application Ser. No. 06/843,286, filed Mar. 24, 1986.
Foreign Referenced Citations (2)
Number |
Date |
Country |
0101552 |
Feb 1984 |
EPX |
0106948 |
May 1984 |
EPX |
Non-Patent Literature Citations (1)
Entry |
Sagawa et al., "New Material for Permanent Magnets on a Base of Nd and Fe", J. Appl. Phys. 55(6), Mar. 15, 1984 pp. 2083-2087. |
Continuations (2)
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Number |
Date |
Country |
Parent |
142356 |
Dec 1987 |
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Parent |
843286 |
Mar 1986 |
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