(19) |
 |
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(11) |
EP 0 286 357 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
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06.06.1990 Bulletin 1990/23 |
(43) |
Date of publication A2: |
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12.10.1988 Bulletin 1988/41 |
(22) |
Date of filing: 05.04.1988 |
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(84) |
Designated Contracting States: |
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DE FR GB |
(30) |
Priority: |
06.04.1987 US 34862
|
(71) |
Applicants: |
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- FORD MOTOR COMPANY LIMITED
Brentwood,
Essex CM13 3BW (GB)
GB
- FORD FRANCE SOCIETE ANONYME
F-92506 Rueil Malmaison Cedex (FR)
FR
- FORD-WERKE AKTIENGESELLSCHAFT
D-50725 Köln (DE)
DE
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(72) |
Inventors: |
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- Patel, Suresh G.
Canton
Michigan 48187 (US)
- Hadjipanayis, George C.
Manhattan, KS 66502 (US)
- Christoduoulou, Christodoulos
Pittsburgh PA 15206 (US)
- Abbott, Edward H.
Ann Arbor
Michigan 48104 (US)
- Erickson, Robert H.
West Bloomfield
Michigan 48003 (US)
|
(74) |
Representative: Messulam, Alec Moses et al |
|
A. Messulam & Co.
24 Broadway Leigh on Sea
Essex SS9 1BN Leigh on Sea
Essex SS9 1BN (GB) |
|
|
|
(54) |
Multiphase permanent magnet of the Fe-B-MM type |
(57) A method is disclosed for producing a permanent magnet of the Fe-B-MM type, comprising:
(a) preparing a metallic powder having a mean particle size of 2-5 microns and having
a composition comprising, by atomic weight percent: 60-80% Fe, 1-8% Al, 6-10% B, .1-.43%
oxygen, 0-5% Dy and/or 0-10% Ni, and 12-22% MM, where MM is a misch metal (preferably
having at least four naturally occurring insoluble cerium earth metals with a least
20% of the misch metal consisting of cerium and lanthanum), the powder having essentially
a multiphase crystalline structure dominated by at least two R₂Fe₁₄B phases; (b) aligning
such powder in a magnetic field; (c) compacting the aligned powder into shapes; (d)
sintering such shapes at a temperature and for a period of time (i.e., in the range
of 1000-1100°C for .5-9 hours) to fuse the powder and increase the proportion of said
R₂Fe₁₄B phases to at least 70% by volume of the shapes; and preferably (e) anealing
the sintered shapes at a temperature (i.e., in the range of 550-650°C for 1-4 hours)
to cause the shapes to consist essentially of at least two R₂Fe₁₄B phases comprising
the matrix and the phase RFe₄B₄ and the R-rich phase residing essentially in the grain
boundaries.
