| (19) |
 |
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(11) |
EP 0 632 471 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
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15.02.1995 Bulletin 1995/07 |
| (43) |
Date of publication A2: |
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04.01.1995 Bulletin 1995/01 |
| (22) |
Date of filing: 09.06.1994 |
|
| (51) |
International Patent Classification (IPC)6: H01F 1/053 |
|
| (84) |
Designated Contracting States: |
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AT DE ES FR GB IT NL SE |
| (30) |
Priority: |
14.06.1993 JP 142156/93
|
| (71) |
Applicant: SANTOKU METAL INDUSTRY CO., LTD. |
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Kobe-shi,
Hyogo-ken (JP) |
|
| (72) |
Inventors: |
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- Yamamoto, Kazuhiko
Kobe-shi,
Hyogo-ken (JP)
- Miyake, Yuichi
Kasai-shi,
Hyogo-ken (JP)
- Okada, Chikara
Kobe-shi,
Hyogo-ken (JP)
|
| (74) |
Representative: Kraus, Walter, Dr. et al |
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Patentanwälte Kraus, Weisert & Partner
Thomas-Wimmer-Ring 15
D-80539 München
D-80539 München (DE) |
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| |
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| (54) |
Permanent magnet containing rare earth metal, boron and iron |
(57) A permanent magnet is obtained by pulverizing, molding and sintering a starting material
containing an alloy ingot. The alloy ingot contains not less than 90% by volume of
prismatic crystals each having a prismatic crystal grain size of 0.1 to 50 µm along
a short axis thereof and a prismatic crystal grain size of larger than 100 µm and
not larger than 300 µm along a long axis thereof, and is obtained by uniformly solidifying
by a single roll method a molten alloy containing 25 to 31% by weight of a rare earth
metal, 0.5 to 1.5% by weight of boron and iron under cooling conditions of a cooling
rate of higher than 500°C/sec. and not higher than 10,000°C/sec. and a supercooling
degree of 50 to 500°C.