Claims
- 1. A thermally stable permanent magnet with reduced irreversible loss of flux and improved intrinsic coercivity iHc of about 20.5 KOe or more having the following composition:
- (Nd.sub.1-.alpha. Dy.sub..alpha.)(Fe.sub.1-x-y-z Co.sub.x B.sub.y M.sub.z).sub.a
- wherein M represents at least one element selected from the group consisting of Nb, Mo, Al, Si, P, Zr, Cu, V, W, Ti, Ni, Cr, Hf, Mn, Bi, Sn, Sb and Ge, 0.01.ltoreq.x.ltoreq.0.4, 0.04.ltoreq.y.ltoreq.0.20, 0.ltoreq.z.ltoreq.0.03, 4.ltoreq.a.ltoreq.7.5, and 0.03.ltoreq..alpha..ltoreq.0.40 wherein the irreversible loss of flux is 10% or less at 200.degree. C. and Pc=2.
- 2. A thermally stable permanent magnet with reduced irreversible loss of flux of less than 3.0% at 200.degree. C. and Pc=2 and improved intrinsic coercivity of 23 KOe or more having the following composition:
- (Nd.sub.1-.alpha. Dy.sub..alpha.)(Fe.sub.1-x-y-z Co.sub.x B.sub.y M.sub.z).sub.a
- wherein M represents at least one element selected from the group consisting of Nb, Mo, P and V, and wherein 0.01.ltoreq.x.ltoreq.0.4, 0.04.ltoreq.y.ltoreq.0.20, 0.ltoreq.z.ltoreq.0.03, 4.ltoreq.a.ltoreq.7.5, and 0.03.ltoreq..alpha..ltoreq.0.40.
- 3. The thermally stable permanent magnet as in claim 1 and being made by (a) sintering an alloy having said composition by a powder metallurgy method; (b) heating the sintered body at 750.degree.-1000.degree. C. for 0.2-5 hours; (c) slowly cooling it at a cooling rate of 0.3.degree.-5.degree. C./min. to temperatures between room temperature and 600.degree. C; (d) heating it at 540.degree.-640.degree. C. for 0.2-3 hours; and (e) rapidly cooling it at a cooling rate of 20.degree.-400.degree. C./min.
Priority Claims (1)
Number |
Date |
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61-7111 |
Jan 1986 |
JPX |
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Parent Case Info
This application is a continuation under 37 CFR 1.62 of prior application Ser. No. 07/299,473 filed Jan. 18, 1989, now abandoned, which is a divisional application of Ser. No. 07/000,103 filed Jan. 2, 1987, now abandoned.
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Number |
Name |
Date |
Kind |
4597938 |
Matsuura et al. |
Jul 1986 |
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4767450 |
Ishigaki et al. |
Aug 1988 |
|
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EPX |
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JPX |
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JPX |
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JPX |
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JPX |
Non-Patent Literature Citations (1)
Entry |
Narasimhan, "Comparative Study of NdFeB and `2:7` Rare Earth Magnets", Dayton, Ohio, May 1985, pp. 459-473. |
Divisions (1)
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Number |
Date |
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Parent |
103 |
Jan 1987 |
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Continuations (1)
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Number |
Date |
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Parent |
299473 |
Jan 1989 |
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