Magnetic materials and permanent magnets

• US 4,770,723 A
• Filed: 02/10/1987
• Issued: 09/13/1988
• Est. Priority Date: 08/21/1982
• Status: Expired due to Term

• Current Assignee: Sumitomo Seika Chemicals Company Limited
• Original Assignee: Sumitomo Seika Chemicals Company Limited
• Inventors: Matsuura, Yutaka, Sagawa, Masato, Fujimura, Setsuo
• Primary Examiner(s): Sheehan, John P.
• Application Number:
  US07/013,165
• Time in Patent Office: 581 Days
• Field of Search: 148/302, 420/83, 420/121, 75/251, 75/244, 75/245, 75/246
• US Class Current: 148/302
• CPC Class Codes: C22C 1/0441 Alloys based on intermetallic compounds of the type rare earth - Co, Ni
• CPC Class Codes: H01F 1/057 and IIIa elements, e.g. Nd2Fe14B
• CPC Class Codes: H01F 1/0577 sintered

Abstract

Magnetic materials comprising Fe, B and R (rare earth elements) having a major phase of Fe--B--R intermetallic compound(s) of tetragonal system, and sintered anisotropic permanent magnets consisting essentially of, by atomic percent, 8-30% R (at least one of rare earth elements inclusive of Y), 2-28% B and the balance being Fe with impurities. Those may contain additional elements M (Ti, Ni, Bi, V, Nb, Ta, Cr, Mo, W, Mn, Al, Sb, Ge, Sn, Zr, Hf) providing Fe--B--R--M type materials and magnets.

Claims

1. An anisotropic magnetic material having a mean crystal grain size of at least about 1 micron, an intrinsic coercivity of at least 1 kOe and having a maximum energy product of at least 10 MGOe upon sintering, said material consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B and the balance being at least 56 percent Fe, in which at least 50 vol % of the entire material is occupied by a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure.

23. A magnetic material as defined in claim 1 or 12, wherein R is about 15 at % and B is about 8 at %.

27. A magnetic article in the form of powder compact or sintered mass of the magnetic material as defined in any of claims 1 and 12.

32. A magnetic material as defined in claim 1, 12, 24 or 30 wherein said Fe--B--R type tetragonal crystal structure has the lattice constants a_o of about 8.8 angstroms and c_o of about 12 angstroms.

33. A magnetic article in the form of powder compact or sintered mass of the magnetic material as defined in claim 32.

34. A magnet or material as defined in claim 1, 2, 3, 12, 13, 14, 29 or 30 which is substantially Co-free.

35. A magnet or material as defined in claim 1, 3, 12, 14, 29 or 30 wherein oxygen is present in an amount of not more than 1 at %.

2. A sintered anisotropic permanent magnet having maximum energy product of at least 10 MGOe and consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B and the balance being at least 56 percent Fe.

5. A permanent magnet as defined in claim 2 or 3, in which the mean crystal grain size is in the range of from 1 to 80 microns.

6. A permanent magnet as defined in claim 5, in which the mean crystal grain size is in the range of from 2 to 40 microns.

7. A permanent magnet as defined in claim 2 or 3 in which Sm is no more than 2 atomic percent in the entire magnet.

8. A permanent magnet as defined in claim 2 or 3, in which R is about 15 atomic percent, and B is about 8 atomic percent.

9. A permanent magnet as defined in claim 2 or 3, in which the maximum energy product is no less than 20 MGOe.

10. A permanent magnet as defined in claim 9, in which the maximum energy product is no less than 30 MGOe.

11. A permanent magnet as defined in claim 10, in which the maximum energy product is no less than 35 MGOe.

3. A sintered anisotropic permanent magnet having a mean crystal grain size of at least about 1 micron and consisting essentially of, by atomic percent 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B and the balance being at least 56 percent Fe, in which at least 50 vol % of the entire magnet is occupied by a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure, said magnet having a maximum energy product of at least 10 MGOe.

4. A permanent magnet as defined in claim 3, which contains no less than 1 vol % of nonmagnetic phases.

12. An anisotropic magnetic material having a mean crystal grain size of at least about 1 micron and an intrinsic coercivity of at least 1 kOe and having a maximum energy product of at least 10 MGOe upon sintering, said material consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B, at least one additional element M selected from the group given below in the amounts of no more than the atomic percentages specified below wherein the sum of M is no more than the maximum value of any one of the values specified below for M actually added and the balance being at least 56 percent Fe, in which a crystal phase of a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure occupies at least 50 vol % of the entire material:

space="preserve" listing-type="tabular">______________________________________ 3.3% Ti, 4.5% Ni, 5.0% Bi, 6.6% V, 10.0% Nb, 8.4% Ta, 5.6% Cr, 6.2% Mo, 5.9% W, 3.5% Mn, 6.4% Al, 1.4% Sb, 4.5% Ge, 1.8% Sn, 3.7% Zr, and 3.7% Hf. ______________________________________

13. A sintered anisotropic permanent magnet having a maximum energy product of at least 10 MGOe and consisting essentially of, by atomic percent, 12-20 percent R wherein R is at leat one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B, at least one additional element M selected from the group given below in the amounts of no more than the atomic percentages specified below, wherein the sum of M is no more than the maximum value of any one of the values specified below for M actually added and the balance being at least 56 percent Fe,:

space="preserve" listing-type="tabular">______________________________________ 3.3% Ti, 4.5% Ni, 5.0% Bi, 6.6% V, 10.0% Nb, 8.4% Ta, 5.6% Cr, 6.2% Mo, 5.9% W, 3.5% Mn, 6.4% Al, 1.4% Sb, 4.5% Ge, 1.8% Sn, 3.7% Zr, and 3.7% Hf. ______________________________________

16. A permanent magnet as defined in claim 13 or 14, in which the mean crystal grain size is in the range of from 1 to 90 microns.

17. A permanent magnet as defined in claim 16, in which the mean crystal grain size is in the range of from 2 to 40 microns.

18. A permanent magnet as defined in claim 13 or 14, in which Sm is no more than 2 atomic percent in the entire magnet.

19. A permanent magnet as defined in claim 13 or 14, in which R is about 15 atomic percent, and B is about 8 atomic percent.

20. A permanent magnet as defined in claim 13 or 14, in which the maximum energy product is no less than 20 MGOe.

21. A permanent magnet as defined in claim 20, in which the maximum energy product is no less than 30 MGOe.

22. A permanent magnet as defined in claim 21, in which the maximum energy product is no less than 35 MGOe.

25. A permanent magnet as defined in claim 13 or 14 wherein said additional elements M is at least one selected from the group consisting of V, Nb, Mo, W and Al.

26. A magnet as defined in claim 25, wherein said additional elements M is contained no more than the amount by atomic percent as specified below:

space="preserve" listing-type="tabular">______________________________________ 3.7% V, 6.2% Nb, 4.0% Mo, 3.7% W, and 3.4% Al;

______________________________________

wherein the sum of M is no more than the maximum value of any one of the values specified above for M actually added.

28. A sintered anisotropic permanent magnet as defined in claim 2, 3, 13 or 14, wherein Si is present in an amount of at most 5 at %.

31. A sintered anisotropic permanent magnet as defined in claim 2, 3, 13 or 14, wherein R is Nd.

14. A sintered anisotropic permanent magnet having a mean crystal grain size of at least about 1 micron and consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B, at least one additional element M selected from the group given below in the amounts no more than the atomic percentages specified below, wherein the sum of M is no more than the maximum value of any one of the values specified below for M actually added and the balance being at least 56 percent Fe:

space="preserve" listing-type="tabular">______________________________________ 3.3% Ti, 4.5% Ni, 5.0% Bi, 6.6% V, 10.0% Nb, 8.4% Ta, 5.6% Cr, 6.2% Mo, 5.9% W, 3.5% Mn, 6.4% Al, 1.4% Sb, 4.5% Ge, 1.8% Sn, 3.7% Zr, and 3.7% Hf ______________________________________

in which a crystal phase of a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure occupies at least 50 vol % of the entire magnet, said permanent magnet having a maximum energy product of at least 10 MGOe.

15. A permanent magnet as defined in claim 14, which contains no less than 1 vol % of nonmagnetic phases.

24. A sintered anisotropic permanent magnet as defined in claim 3 or 14 wherein said Fe--B--R type tetragonal crystal structure has the lattice constants a_o of about 8.8 angstroms and c_o of about 12 angstroms.

29. A powdery magnetic material capable of uniaxial alignment upon orientation in a magnetic field to provide magnetic anisotropy, and having a maximum energy product of at least 10 MGOe and an intrinsic coercivity of at least 1 kOe upon sintering, said material having a mean crystal grain size of at least about 1 micron, and consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4-24 percent B and the balance being at least 56 percent Fe, in which at least 50 vol % of the entire material is occupied by a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure.

30. A powdery magnetic material capable of uniaxial alignment upon orientation in a magnetic field to provide magnetic anisotropy, and having a maximum energy product of at least 10 MGOe and an intrinsic coercivity of at least 1 kOe upon sintering, said material having a mean crystal grain size of at least about 1 micron, and consisting essentially of, by atomic percent, 12-20 percent R wherein R is at least one element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and wherein at least 50% of R consists of Nd and/or Pr, 4--24 percent B, at least one additional element M selected from the group given below in the amounts of no more than the atomic percentages specified below wherein the sum of M is no more than the maximum value of any one of the values specified below for M actually added and the balance being at least 56 percent Fe, in which crystal phase of a ferromagnetic compound having a Fe--B--R type tetragonal crystal structure occupies at least 50 vol % of the entire material:

space="preserve" listing-type="tabular">______________________________________ 3.3% Ti, 4.5% Ni, 5.0% Bi, 6.6% V, 10.0% Nb, 8.4% Ta, 5.6% Cr, 6.2% Mo, 5.9% W, 3.5% Mn, 6.4% Al, 1.4% Sb, 4.5% Ge, 1.8% Sn, 3.7% Zr, and 3.7% Hf. ______________________________________