U.S. patent number RE34,838 [Application Number 07/572,568] was granted by the patent office on 1995-01-31 for permanent magnet and method for producing same.
This patent grant is currently assigned to TDK Corporation. Invention is credited to Kaneo Mohri, Jiro Yamasaki.
United States Patent |
RE34,838 |
Mohri , et al. |
January 31, 1995 |
Permanent magnet and method for producing same
Abstract
In the rare earth-iron-boron permanent magnet, Ce and La
decrease the magnetic properties when used alone but
synergistically enhance iHc when used in combination. The
composition provided by the present invention is generally
expressed by [(Ce.sub.x La.sub.1-x).sub.y R.sub.1-y ].sub.2
[(Fe.sub.1-u-w Co.sub.w M.sub.u).sub.1-v B.sub.v ].sub.1-z with a
proviso of 0.4.ltoreq.x.ltoreq.0.9, 0.2<y.ltoreq.1.0,
0.05.ltoreq.z.ltoreq.0.3, 0.01.ltoreq.v.ltoreq.0.3,
0.ltoreq.u.ltoreq.0.2, 0.ltoreq.w.ltoreq.0.5, and M is at least one
element selected from the group consisting of Al, Ti, V, Cr, Mn,
Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag.
Inventors: |
Mohri; Kaneo (Fukuoka,
JP), Yamasaki; Jiro (Fukuoka, JP) |
Assignee: |
TDK Corporation (Tokyo,
JP)
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Family
ID: |
27566528 |
Appl.
No.: |
07/572,568 |
Filed: |
August 23, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
814183 |
Dec 27, 1985 |
04765848 |
Aug 23, 1988 |
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Foreign Application Priority Data
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Dec 31, 1984 [JP] |
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59-280125 |
Sep 17, 1985 [JP] |
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60-205004 |
Sep 17, 1985 [JP] |
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60-205005 |
Sep 17, 1985 [JP] |
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60-205006 |
Nov 21, 1985 [JP] |
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60-259816 |
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Current U.S.
Class: |
148/302; 420/121;
420/83 |
Current CPC
Class: |
H01F
1/0571 (20130101); H01F 1/0577 (20130101); H01F
1/0578 (20130101) |
Current International
Class: |
H01F
1/057 (20060101); H01F 1/032 (20060101); H01F
001/04 () |
Field of
Search: |
;148/302
;420/83,121 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0101552 |
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Feb 1984 |
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EP |
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0106948 |
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May 1984 |
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EP |
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55-24909 |
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Feb 1980 |
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JP |
|
58-123853 |
|
Jul 1983 |
|
JP |
|
59-46008 |
|
Mar 1984 |
|
JP |
|
59-64733 |
|
Apr 1984 |
|
JP |
|
59-64739 |
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Apr 1984 |
|
JP |
|
59-76856 |
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May 1984 |
|
JP |
|
59-211549 |
|
Nov 1984 |
|
JP |
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60-145357 |
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Jul 1985 |
|
JP |
|
60-184603 |
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Sep 1985 |
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JP |
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60-194502 |
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Oct 1985 |
|
JP |
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60-221550 |
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Nov 1985 |
|
JP |
|
60-224757 |
|
Nov 1985 |
|
JP |
|
60-224761 |
|
Nov 1985 |
|
JP |
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60-238448 |
|
Nov 1985 |
|
JP |
|
61-80805 |
|
Apr 1986 |
|
JP |
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Primary Examiner: Sheehan; John P.
Attorney, Agent or Firm: Burgess, Ryan and Wayne
Claims
We claim:
1. A permanent .[.magnet.]. .Iadd.magnetic powder or ribbon
obtained by the rapid cooling method and .Iaddend.having a
composition expressed by (Ce.sub.x La.sub.1-x).sub.z (Fe.sub.1-v
B.sub.v).sub.1-z, with a proviso of 0.4.ltoreq.x.ltoreq.0.9,
0.05.ltoreq.z.ltoreq.0.3, and 0.01.ltoreq.v.ltoreq.0.3 and having a
coercive force (iHc) of at least 4 kOe. .[.2. A permanent magnet
according to claim 1, wherein said permanent magnet is a sintered
magnet..]. .[.3. A permanent magnet according to
claim 1, wherein said permanent magnet is a bonded magnet..]. 4. A
permanent .[.magnet.]. .Iadd.magnetic powder or ribbon
.Iaddend.according to claim 1, wherein x is from 0.6 to 0.8, v is
from 0.02 to 0.15, and z is
from 0.1 to 0.2. 5. A permanent .[.magnet.]. .Iadd.magnetic powder
or ribbon .Iaddend.according to claim .[.2.]. .Iadd.1.Iaddend.,
wherein v is
from 0.03 to 0.12. 6. A permanent .[.magnet.]. .Iadd.magnetic
powder or ribbon .Iaddend.according to claim .[.2.].
.Iadd.1.Iaddend., wherein x is
approximately 0.65. 7. A permanent magnet .[.according to claim 1,
2, 3, 4, 5, or 6, wherein.]. .Iadd.formed from a rapidly cooled
magnetic material having a composition expressed by (Ce.sub.x
La.sub.1-x).sub.z (Fe.sub.1-v B.sub.v).sub.1-z, with a proviso of
0.4.ltoreq.x.ltoreq.0.9, 0.05.ltoreq.z.ltoreq.0.3, and
0.01.ltoreq.v.ltoreq.0.3 and containing .Iaddend.at least one
element selected from the group consisting of Al, Ti, V, Cr, Mn,
Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag .[.is
contained.]. at an atomic ratio .Iadd.u .Iaddend.of
.Iadd.0<u.ltoreq..Iaddend.0.2 .[.or less.]. based on the sum of
said at least one element and Fe .Iadd.and having a coercive force
(iHC) of at
least 4 KOe.Iaddend.. 8. A permanent magnet according to claim
.[.1, 2, 3, 4, 5, or 6.]. .Iadd.7 or 9.Iaddend., wherein B is
partly replaced with at least one element selected from the group
consisting of Si, C, P, N, Ge, and S in an atomic ratio of 0.5 or
less based on a sum of B and said at
least one element. 9. A permanent magnet according to claim .[.1.].
.Iadd.7.Iaddend., wherein Co is contained at an atomic ratio (w)
and at least one element selected from the group consisting of Al,
Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu and Ag
is contained at an atomic ratio (u), wherein said (w) is from more
than 0 to 0.5 and said (u) is from .[.0.]. .Iadd.0.001 .Iaddend.to
0.2, with the proviso that sum of
(u), (w) and atomic ratio of Fe is 1.0. 10. A permanent magnet
according to claim .Iadd.7 or .Iaddend.9, wherein said permanent
magnet is a
sintered magnet. 11. A permanent magnet according to claim .Iadd.7
or
.Iaddend.9, wherein said permanent magnet is a bonded magnet. 12. A
permanent magnet according to claim .Iadd.7 or .Iaddend.9, wherein
x is
from 0.6 to 0.8, v is from 0.02 to 0.15, and z is from 0.1 to 0.2.
13. A permanent magnet according to claim .[.10.]. .Iadd.7 or
9.Iaddend.,
wherein v is from 0.03 to 0.12. 14. A permanent magnet according to
claim .[.10.]. .Iadd.7 or 9.Iaddend., wherein x is approximately
0.65. .[.15. A permanent magnet having a composition of [(Ce.sub.x
La.sub.1-x).sub.y R.sub.1-y ].sub.z (Fe.sub.1-v B.sub.v).sub.1-z,
wherein R is at least one rare earth element except for Ce and La,
but including Y with a proviso of 0.4.ltoreq.x.ltoreq.0.9,
0.2<y<1.0, 0.05.ltoreq.z.ltoreq.0.3,
0.001.ltoreq.v.ltoreq.0.3, and having a coercive force (iHc) of at
least 4 kOe..]. .[.16. A permanent magnet according to claim 15,
wherein said permanent magnet is a sintered magnet..]. .[.17. A
permanent magnet according to claim 15, wherein said permanent
magnet is a bonded
magnet..]. 18. A permanent .[.magnet.]. .Iadd.magnetic powder or
ribbon .Iaddend.according to claim .[.15.]. .Iadd.34.Iaddend.,
wherein x is from
0.6 to 0.8, v is from 0.02 to 0.15, and z is from 0.1 to 0.2. 19. A
permanent .[.magnet.]. .Iadd.magnetic powder or ribbon
.Iaddend.according
to claim .[.18.]. .Iadd.34.Iaddend., wherein v is from 0.03 to
0.12. 20. A permanent .[.magnet.]. .Iadd.magnetic powder or ribbon
.Iaddend.according to claim .[.19.]. .Iadd.34.Iaddend., wherein x
is approximately 0.65. .[.21. A permanent magnet according to claim
15, 16, 17, 18, 19, or 20, wherein at least one element selected
from the group consisting of Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo,
Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag is contained at an atomic ratio
of 0.2 or less based on the sum of said at
least one element and Fe..]. 22. A permanent magnet according to
claim .[.15, 16, 17, 18, 19 or 20.]. .Iadd.23 or 31.Iaddend.,
wherein B is partly replaced with at least one element selected
from the group consisting of Si, C, P, N, Ge, and S in an atomic
ratio of 0.5 or less
based on a sum of B and said at least one element. 23. A permanent
magnet according to claim .[.15.]. .Iadd.31.Iaddend., wherein Co is
contained at an atomic ratio (w) and at least one element selected
from the group consisting Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo,
Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag is contained at an atomic ratio
(u), wherein said (w) is from more than 0 to 0.5 and said (u) is
from .[.0.]. .Iadd.0.001 .Iaddend.to 0.2, with the proviso that sum
of (u), (w) and atomic ratio of Fe is 1.0.
4. A permanent magnet according to claim 23 .Iadd.or 31.Iaddend.,
wherein
said permanent magnet is a sintered magnet. 25. A permanent magnet
according to claim 23 .Iadd.or 31.Iaddend., wherein said permanent
magnet
is a bonded magnet. 26. A permanent magnet according to claim 23
.Iadd.or 31.Iaddend., wherein x is from 0.6 to 0.8, v is from 0.02
to 0.15, and z
is from 0.1 to 0.2. 27. A permanent magnet according to claim
.[.26.].
.Iadd.23 or 31.Iaddend., wherein v is from 0.03 to 0.12. 28. A
permanent magnet according to claim .[.26.]. .Iadd.23 or
31.Iaddend., wherein x is approximately 0.65. .[.29. A permanent
magnet having a composition of [(Ce.sub.x La.sub.1-x).sub.y
R.sub.1-y ].sub.z [(Fe.sub.1-u-w Co.sub.w M.sub.u).sub.1-v B.sub.v
].sub.1-z with a proviso of 0.4.ltoreq.x.ltoreq.0.9,
0.2<y.ltoreq.1.0, 0.05.ltoreq.z.ltoreq.0.3,
0.01.ltoreq.v.ltoreq.0.3, 0.ltoreq.u.ltoreq.0.2,
0.ltoreq.w.ltoreq.0.5, and M is at least one element selected from
the group consisting of Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge,
Sb, Sn, Bi, Ni, W, Cu, and Ag, having a coercive force (iHc) of at
least 4 kOe, having been plastically
worked. 30. A permanent magnet according to claim .[.29.].
.Iadd.33.Iaddend., wherein the plastic working method is a method
selected from the group consisting of hot-pressing, swaging,
extruding, forging, and rolling. .Iadd.31. A permanent magnet
formed from a rapidly cooled magnetic material having a composition
of [((Ce.sub.x La.sub.1-x).sub.y R.sub.1-y).sub.z ]((Ce.sub.x
La.sub.1-x).sub.y R.sub.1-y).sub.z (Fe.sub.1-v B.sub.v).sub.1-z
wherein R is at least one rare earth element except for Ce and La,
but including Y with a proviso of 0.4.ltoreq.x.ltoreq.0.9,
0.2<y<1.0, 0.05.ltoreq.z.ltoreq.0.3, 0.01.ltoreq.v.ltoreq.0.3
containing at least one element selected from the group consisting
of Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W,
Cu, and Ag at an atomic ratio u of 0<u.ltoreq.0.2 based on the
sum of said at least one element and Fe, having a coercive force
(iHc) of at least 4 KOe. .Iaddend. .Iadd.32. A permanent magnet
formed of a magnetic powder of claims 1 or 34. .Iaddend. .Iadd.33.
A permanent magnet having a composition of ((Ce.sub.x
La.sub.1-x).sub.y R.sub.1-y).sub.z (Fe.sub.1-u-w Co.sub.w
M.sub.u).sub.1-y B.sub.v ].sub.1-z with a proviso of
0.4.ltoreq.x.ltoreq.0.9, 0.2<y<1.0, 0.05.ltoreq.z.ltoreq.0.3,
0.01.ltoreq.v.ltoreq.0.3, 0.ltoreq.u.ltoreq.0.2,
0.ltoreq.w.ltoreq.0.5, and M is at least one element selected from
the group consisting of Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge,
Sb, Sn, Bi, Ni, W, Cu, and Ag having a coercive force (IiHc) of at
least 4 kOe, comprising a rapidly cooled magnetic material which
has been plastically worked. .Iaddend. .Iadd.34. A permanent
magnetic powder or ribbon obtained by a rapid cooling method having
a composition of ((Ce.sub.x La.sub.1-x).sub.y R.sub.1-y).sub.z
(Fe.sub.1-v B.sub.v).sub.1-z, wherein R is at least one rare earth
element except for Ce and La but including Y with a proviso of
0.4.ltoreq.x.ltoreq.0.9, 0.2<y<1.0, 0.5.ltoreq.z.ltoreq.0.3,
0.01.ltoreq.v.ltoreq.0.3, and having a coercive force (iHc) of at
least 4 KOe. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rare-earth-iron-boron permanent
magnet.
2. Description of the Related Art
Recently, permanent magnets containing rare earth, Fe, and, B as
the basic components have been closely studied, and the results of
these studies have been published in patent documents and the
like.
Japanese Unexamined Patent Publication No. 57-141901 discloses a
method for producing a permanent magnet powder wherein the
composition of a transition group metal (T), metalloid metal (M),
and a lanthanoid element (R) is glassified, and the obtained
amorphous composition is then crystallized and a coercive force is
generated by heat treatment. According to this publication, T is
one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zr, Nb, Mo, Hf, Ta, and W; M is one or more elements selected from
B, Si, P, and C; and R is one or more elements selected from Y and
lanthanoid elements. This publication claims a permanent magnet
powder expressed by the formula (T.sub.1-x M.sub.x).sub.z
R.sub.1-z, wherein 0.ltoreq.x.ltoreq.0.35 and
0.35.ltoreq.z.ltoreq.0.90.
Japanese Unexamined Patent Publication No. 58-123853 proposes a La-
and Pr-containing material having the composition (Fe.sub.x
B.sub.1-x).sub.y -(La.sub.z Pr.sub.w R.sub.1-z-w).sub.1-y, in which
R is one or more rare earth elements except for La and Pr,
x=0.75.about.0.85, y=0.85.about.0.95, z=0.40.about.0.75,
w=0.25.about.0.60, and z+w.ltoreq.1.0. According to this
publication, the kinds and proportion of rare-earth elements are
adjusted to provide the above composition (La.sub.z Pr.sub.w
R.sub.1-z-w) so as to attain an appropriate enhancement of the
coercive force at the annealing and crystallizing of the rare
earth-iron-boron alloy. The coercive force is enhanced at
approximately 3 kOe.
Japanese Unexamined Patent Publication No. 59-46008 proposes a
magnetically anisotropic sintered body consisting of from 8 to 30
atomic % of R (at least one of the rare earth elements), from 2 to
28 atomic % of B, and Fe in balance. The invention of this
publication aims at producing a permanent magnet having a desired
shape by the sintering method, since the method of rapid cooling
the melt brings about certain limitations in the magnet shape. The
above publication discloses, as R, Nd alone, Pr alone, a
combination of Nd and Pr, a combination of Nd and Ce, a combination
of Sm and Pr, Tb alone, Dy alone, Ho alone, and a combination of Er
and Tb.
The above prior art disclose that excellent magnetic properties are
obtained for the rare earth-iron-boron magnet, in which the rare
earth element is Nd or Pr. In addition, La and Ce are set forth in
the claim in the unexamined patent publications as the rare earth
elements, but the highest content of La and Ce are limited so as
not to incur a reduction in the magnetic properties. There is a
substantial absence of disclosure directed to the rare
earth-iron-boron permanent magnet, the rare earth components of
which are mainly composed of La and Ce. This is further explained
with reference to FIG. 1.
Referring to FIG. 1, Pr and Nd as the rare earth components of the
rare earth-iron-boron permanent magnet exhibit the best magnetic
properties. When La or Ce is used as the rare earth component, the
alloy consisting of La or Ce, Fe, and B cannot exhibit the same
magnetic properties as the permanent magnet. FIG. 1 teaches that
the replacement of Nd, and Pr with La or Ce causes a reduction in
the magnetic properties required for the permanent magnet. Based on
the teaching of FIG. 1, it can be said that the prior arts
explained above teach R-Fe-B alloy which can exhibit the magnetic
properties required for the permanent magnet only at a slight
replacement of Nd and Pr with La or Ce but not an alloy wherein the
rare earth elements are composed mainly or totally of La or Ce.
A recent prominent advancement of the rare earth-iron-boron
permanent magnet is disclosed in the publication "DIDYMIUM-Fe-B
SINTERED PERMANENT MAGNETS" at MMM on October 1984, which attained
a coercive force (iHc) of 10.2 kG and a maximum energy product
((BH) max) of 40MGOe by a magnet consisting of 32.5.about.34.5% of
R, 1.about.1.6% of B, and balance of iron, wherein R is (Nd -10%
Pr), 5% Ce-didymium, or 40% Ce-didymium. In this permanent magnet,
the main rare earth component is also Nd.
Japanese Unexamined Patent Publication No. 60-100402 discloses a
method in which melt containing Fe, B, and Nd and/or Pr is rapidly
cooled to form amorphous or finely crystalline, solid material, and
further, it is subjected to a high-temperature treatment by
hot-pressing to form a plastically deformed body having a
microstructure formed by fine particles, followed by cooling.
The time duration of the high-temperature treatment and the cooling
speed are adjusted to induce a magnetic anisotropy in the resultant
permanent magnet body.
One of the drawbacks of the permanent magnet, the main components
of which are rare earth elements Fe, and B, is that Nd, or Pr must
be the main components of the rare earth elements to attain
excellent magnetic properties, and hence the permanent magnet
becomes expensive. The permanent magnet containing dydimium is
attractive, since the dydimium is inexpensive, and further, the
permanent magnet can exhibit magnetic properties comparable to
magnets containing Nd and Pr.
If La or Ce can be contained in the rare earth-iron-boron magnet as
a main component(s) of the rare earth components, a drastic cost
reduction of such a magnet becomes possible, since La and Ce are
available in a greater amount than the other rare earth elements
and hence are inexpensive. Nevertheless, La and Ce are detrimental
to the magnetic properties, as is understood from FIG. 1. The
ferromagnetic crystal of the rare earth-iron-boron magnet is an
R.sub.2 Fe.sub.14 B compound which becomes unstable or is not at
all formed when R is La. When R is Ce although R(Ce).sub.2
Fe.sub.14 B is formed, the coercive force of this compound becomes
low.
As described above, there is a substantial absence of any
disclosure in the prior art for replacing Nd, Pr, and the like with
a large quantity of La or Ce.
The plastic working method disclosed in Japanese Unexamined Patent
Publication No. 60-100,402, i.e., the hot-working method, involves
a problem in that: an appropriate temperature for the plastic
working is from 700.degree. C. to 850.degree. C. and thus
relatively high; the pressure is from 1 to 3 ton/cm.sup.2 and
relatively high; and, an appropriate pressing time is approximately
5 minutes and thus relatively short. According to this publication,
during plastic working of the microstructure material the magnetic
anisotropy is induced and the magnetic properties are therefore
improved. To improve the magnetic properties, it is crucial to
control the plastic working in terms of temperature, pressure, and
time in such a manner as mentioned above. Such control is
complicated. If the control is unsatisfactory, not only are the
desired magnetic properties unobtainable, but also the shape and
dimension of the products is restricted, so that products
appropriate for various uses cannot be obtained, and this is a
drawback in industrial application. If an appropriate temperature
for the plastic working becomes low, and if the pressure for the
plastic working becomes low, the plastic working method can be
broadly applied for the production of various shapes, for example,
an extremely thin magnet.
The anisotropic magnet having a radial direction of anisotropy is
well known in the field of plastic magnets. The magnetic powder
generally used for the radial anisotropic permanent magnet is Sm-Co
powder. The rare earth-iron-boron magnet has a drawback that, when
pulverized, the coercive force is decreased. Because of this, it
has been heretofore difficult to produce a radial anisotropic
permanent magnet using the rare earth-iron-boron powder.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rare
earth-iron-boron magnet free of the drawbacks described above.
In accordance with the present invention, there is provided a
permanent magnet having a composition (hereinafter referred to as
the "first composition") expressed by (Ce.sub.x La.sub.1-x).sub.z
(Fe.sub.1-v B.sub.v).sub.1-z, with the proviso of
0.4.ltoreq.x.ltoreq.0.9, 0.05.ltoreq.z.ltoreq.0.3, and
0.01.ltoreq.v.ltoreq.0.3, and having a coercive force (iHc) of at
least 4 kOe.
There is also provided a permanent magnet having a composition
(hereinafter referred to as "the second composition") of [(Ce.sub.x
La.sub.1-x).sub.y R.sub.1-y ].sub.z (Fe.sub.1-v B.sub.v).sub.1-z,
wherein R is at least one rare earth element except for Ce and La,
but including Y, with the proviso of 0.4.ltoreq.x.ltoreq.0.9,
0.2<y<1.0, 0.05.ltoreq.z.ltoreq.0.3,
0.01.ltoreq.v.ltoreq.0.3, and having a coercive force (iHc) of at
least 4 kOe.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a graph reproduced from J. Appl. Phys. Vol 55(1984), page
2079, showing the demagnetizing curve of R.sub.0.135 (Fe.sub.0.935
B.sub.0.065).sub.0.865 ;
FIG. 2 is a graph indicating the relationship between the x-value
of Fe.sub.77 (La.sub.1-x Ce.sub.x).sub.17 B.sub.6 and the coercive
force (iHc); and,
FIGS. 3 and 4 are graphs indicating the relationship between the
coercive force (iHc) and the circumferential speed (V) of the
single cooling roll used for cooling Fe.sub.75 M.sub.15 B.sub.10
and Fe.sub.78 M.sub.17 B.sub.5, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 2, the coercive force (iHc) of Fe.sub.77
(La.sub.1-x Ce.sub.x).sub.17 B.sub.6 allow in the form of a sheet
20 .mu.m in thickness and 3 mm in width is shown. This sheet is
formed by a method of rapid cooling of the melt. The values of
coercive force (iHc) of the Fe.sub.77 (La.sub.1-x Ce.sub.x).sub.17
Be.sub.6 alloy with x=1 (i.e., Fe.sub.77 Ce.sub.17 B.sub.6) and x=0
(i.e., Fe.sub.77 La.sub.17 B.sub.6) corresponds to those of "Ce"
and "La" shown in FIG. 1, respectively. There is a slight
difference in the values of coercive force (iHc) between FIGS. 1
and 2 due to the composition change. As is shown in FIG. 2, the
coercive force (iHc) is drastically enhanced by the copresence of
La and Ce, as compared with the case of the presence of La or Ce
above. The coercive force (iHc) amounts to approximately 7 KOe at
the x value of approximately 0.65. This value of coercive force
(iHc) is approximately one half of the rare earth-iron-cobalt
permanent magnet, in which the rare earth component is mainly
composed of Pr or Nd.
The reasons for limiting the quantity of each elements for
(Ce.sub.x La.sub.1-x).sub.z (Fe.sub.1-v B.sub.v).sub.1-z alloy
(first composition) are now explained.
The content (x) of Ce based on the sum of Ce and La is determined
as x=0.4.about.0.9, because at x<0.4 or x>0.9 the coercive
force (iHc) attained is only approximately the same value as
attained by La alone or Ce alone. The content (z) of Ce and La is
determined as z=0.05.about.0.3, because at z<0.05 the squareness
ratio and coercive force (iHc) are low and at z>0.3 the
remanence is low. The content (v) of B based on sum of Fe and B is
from 0.01 to 0.3, because at v<0.01 the coercive force is low
and at v>0.3 the remanence is low. To obtain a high coercive
force (iHc), preferably 0.6.ltoreq.x.ltoreq.0.8,
0.02.ltoreq.v.ltoreq.0.15, and 0.1.ltoreq.z.ltoreq.0.2. More
preferably, v from 0.03 to 0.12 (0.03.ltoreq.v.ltoreq.0.12).
The coercive force (iHc) of at least 4 kOe is an index for a
prominent synergistic effect of Ce and La as is shown in FIG. 2,
and is a magnetic property which allows the permanent magnet
according to the present invention to replace the various permanent
magnets now on the market. The competitiveness of permanent magnets
is determined by the magnetic properties, in view of the cost. In
the present invention, a large quantity of Fe and B, which are
inexpensive, is used, and La and Ce, which are the most abundant
among the rare earth elements, are used, so that the cost of such a
permanent magnet is considerably less than the rare earth-cobalt
magnet and the Pr/Nd-Fe-B magnet. Accordingly, the permanent magnet
according to the present invention is extremely competitive with
the rare earth-cobalt magnet, Pr/Nd-Fe-B magnet, and ferrite
magnet.
FIGS. 3 and 4 are graphs showing the coercive force (iHc) of the
Fe.sub.75 M.sub.15 B.sub.10 and Fe.sub.78 M.sub.17 B.sub.5 alloys,
respectively, in dependency on the circumferential speed V(m/sec)
of a single roll for cooling the melt of the two alloys. The symbol
M of these two alloys is a mixed metal consisting of approximately
32% of La, approximately 48% of Ce, approximately 15 % of Nd,
approximately 4.5% of Pr, approximately 0.3% of Sm, and a balance
of Fe and impurities. The curves--O--indicates the coercive force
(iHc) after rapid cooling. As is apparent from FIGS. 3 and 4, the
coercive force (iHc) amounts to a highest value of approximately 8
kOe at the circumferential speed of the roll (V) of 30 m/sec.
The curves-- --and-- -- indicate the coercive force (iHc) when
rapid cooling at a rate as shown in FIGS. 3 and 4 and then aging at
550.degree. C. and 600.degree. C., respectively are carried out.
These curves indicate that the coercive force (iHc), though low
after cooling, can be enhanced by aging.
The results shown in FIGS. 3 and 4 indicate that the synergistic
effect of La and Ce is attained even in the presence of a minor
quantity of rare earth elements other than La and Ce.
The permanent magnet having the second composition is based upon
the above recognition and contains a rare earth element(s) other
than La and Ce. The ranges of x, y, and z and their preferred
ranges, as well as the reasons for determining them, are the same
as those for the first composition. The content (y) of Ce and La
based on the sum of Ce, La, and R is more than 0.2 (y>0.2) and
less than 1.0 (y<1.0), preferably from 0.5 to less than 1.0
(0.5.ltoreq.y<1.0).
In the alloys having the first and second compositions, at least
one element selected from the group consisting of Al, Ti, Y, Cr,
Mn, Mn, Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag may
be contained at an atomic ratio of 0.2 or less based on the sum of
the at least one element and Fe. These elements such as Al, Ti and
the like are effective for enhancing the coercive force (iHc). When
the atomic ratio (u) exceeds 0.2, the remanence decreases. A
preferred (u) is from 0.001 to 0.1, and more preferred (u) is from
0.002 to 0.05, in the light of high coercive force (iHc) and energy
product. In addition, at least one element selected from the group
consisting of Si, C, P, N. Ge, and S may partly substitute for B of
the first and second compositions, at an atomic ratio of 0.5 or
less based on the sum of B and said at least one element. Boron
which is partly replaced with Si and the like exerts the same
effects as the boron alone.
The first and second compositions may contain Co at an atomic ratio
(w) and at least one element selected from the group consisting of
Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu,
and Ag is contained at an atomic ratio (u), wherein said (w) is
from more than 0 to 0.5 and said (u) is from 0 to 0.2, with the
proviso that sum of (u), (w) and atomic ratio of Fe is 1.0.
Co enhances the Curie point and improves the magnetic properties,
especially the temperature characteristic of remanence (Br). When
the atomic ratio (w) exceeds 0.5, the magnet becomes expensive and
the coercive force (iHc) becomes low. A preferred (w) is from 0.001
to 0.35.
The permanent magnet can be produced by a rapid cooling method.
The permanent magnet also can be produced by rapidly cooling and
then aging the product. The aging at a temperature of from
350.degree. C. to 950.degree. C. can increase the coercive force
(iHc).
The permanent magnet according to the present invention can also be
produced by a sintering method as explained hereinafter.
The raw materials are mixed to obtain a predetermined composition
and are then melted within an inert gas atmosphere, such as argon
atmosphere, or under vacuum. The melt is then cast into an ingot.
Instead of forming an ingot, a ribbon or powder may be formed of
means of rapidly cooling the melt which may be obtained by melting
the predetermined composition of the raw materials or by remelting
the ingot. Subsequently, the obtained ingot, ribbon or powder is
solutionized and then aged, if necessary, and is then pulverized.
The pulverizing is carried out by a conventional rough crushing and
fine crushing. The obtained magnet-alloy powder usually has a size
of from 2 to 15 .mu.m. The magnet-alloy powder is
compression-formed under the absence of a magnetic field or under
magnetic field of from 3 to 15 kOe. The obtained green compact is
sintered at a temperature of from 900.degree. C. to 1200.degree. C.
for the time period of from 0.5 to 6 hours, under vacuum, or in an
inert gas atmosphere. After the sintering, the sintered body is
cooled. If necessary, the aging is carried out at a temperature of
from 350.degree. C. to 950.degree. C. for the time period of from
0.2 to 60 hours. The multiple stage aging, in which the first aging
is at a high temperature with subsequent aging stages carried out
at a lower temperature, is preferred in the light of a high
coercive force.
The permanent magnet according to the present invention can be
produced by bonding the powder with resin or the like, as explained
hereinafter.
The raw materials are mixed to obtain a predetermined composition
and are then melted in an inert gas atmosphere, such as argon
atmosphere, or under vacuum. The melt is then cast into an ingot.
The ingot is crushed into fine pieces and these pieces are melted
and subjected to the rapid cooling method so as to produce a ribbon
or powder. The ribbon or powder is, if necessary, appropriately
heat treated under normal pressure or under the application of
pressure. The pressure application may be carried out by hot
pressing for inducing a uniaxial crystal anisotropy.
The sintered body produced by the above described process may be
aged at a temperature of from 950.degree. C. to 350.degree. C. for
the time period of from 0.2 to 60 hours. The temperature and time
pattern for aging can be varied to obtain the optimum results.
Preferably, the sintered body is aged in an inert gas atmosphere or
under vacuum.
The ribbon, fine pieces, and sintered body are crushed to obtain
the magnet alloy powder. The crushing is carried out by the
conventional rough crushing and fine crushing method. The obtained
magnet-alloy powder has usually a size of from 5 to 300 .mu.m. The
magnet-alloy powder is surface treated, if necessary. The
magnet-alloy powder and a binder are mixed together at a
predetermined proportion. The binder may be either a resin binder
or metal binder. Instead of mixing the binder with the magnet-alloy
powder, the binder may be impregnated into the shaped mass of
magnet alloy powder. The mixed powder and binder are
compression-shaped in the presence of a magnetic field of from 3 to
15 kOe, to shape the mixture.
The binder is satisfactorily hardened after the compression
shaping. The magnet alloy-powder is oriented in the presence of the
magnetic field which is applied to the mixture prior to or during
the compression.
Alternatively, injection molding may be carried out instead of
compression shaping.
The compression force, and the solidification time and temperature
may be those used for the known bonded magnets.
Plastic working methods according to the present invention are
described hereinafter.
(1) Melting Step
Metal, alloy, or a compound as the raw materials are mixed, heated,
and melted in a high frequency melting furnace, electric furnace,
or the like.
(2) Casting Step
Molten alloy is injected through a quartz nozzle onto a cooling
roll in an inert gas atmosphere, such as argon gas, and is rapidly
cooled, so as to form a ribbon having a thickness of several tens
of microns (.mu.m). Alternatively, the molten alloy may be cast as
an ingot or pulverized as powder or pieces. The powder or pieces
may be in any form.
(3) Pulverizing Step
The ribbon is pulverized in an inert gas atmosphere, by means of a
mill, into powder having a diameter in the range of a few microns
(.mu.m) to a few millimeters (.mu.m). The ingot is pulverized
similarly. The pulverizing may be such that minute particles having
a single magnetic domain are obtained. Alternatively, particles
coarser than single domain particles may be obtained. The
pulverizing step may be occasionally omitted.
(4) Forming Step
In this step, the powder is formed to obtain the shape of an
intermediate or final product, and the magnetic anisotropy is
induced by plastic working. The kinds of forming are
powder-compacting, hot-pressing, sintering, swaging, extruding,
forging, rolling, and the like. The final product can be shaped
into a sheet, a ring, a rod, or a block, etc.
Material having a ridigity appropriate for the plastic working,
such as the green compact or sintered body, is subjected to
deformation by the plastic working, e.g., hot-pressing, swaging,
extruding, forcing, rolling, and the like. The once plastically
worked material may be again plastically worked.
When plastically working the hot-pressed body, the powder is
hot-pressed in an inert gas atmosphere or vacuum, and the
hot-pressed powder is heated to a temperature of from 600.degree.
C. to 1100.degree. C. in an electric furnace or by induction
heating in an inert gas atmosphere or vacuum and then plastically
worked under the temperature-elevated condition.
When plastically working the sintered body, the sintering is
carried out at a temperature of from 800.degree. C. to 1150.degree.
C. and the plastic working then carried out at a
temperature-elevated state up to 600.degree. C. to 1100.degree.
C.
When carrying out the plastic working by hot pressing, the
hot-pressing for obtaining an intermediate or final product is
carried out under a pressure ranging from 200 to 1000 kg/cm.sup.2
and at a time ranging from 1 to 300 minutes. The magnetic
properties are stable regardless of variation in the plastic
working condition within the above ranges, and the products having
stable magnetic properties are easily industrially produced.
When carrying out the plastic working by extrusion, products having
stable magnetic properties are obtained at the extrusion pressure
ranging from 400 to 3000 kg/cm.sup.2.
The permanent magnet according to the present invention is
plastically worked at a rate of from 5 to 80%. This rate refers to
the degree of working from the starting material to the final
product, expressed as usual in terms of reduction in thickness or
cross sectional area. The plastic working can be carried out at any
time for forming the starting material into the final product. The
single plastic working at 80% can be applied to the starting
material for forming the final product. When the deformation force
is imparted to a workpiece in a radial direction, such as in the
extrusion and swaging, a radially oriented magnet can be obtained
by this plastic working, since the alloy particles are radially
oriented at a high degree, with the proviso that the working degree
is 30% or more.
The permanent magnet having the compositions explained above has
improved plastic workability due to the Ce, La, R, Fe, and B, and
magnetic anisotropy is induced due to warm hot-working. The
permanent magnet may be subjected to any plastic working but is
preferably subjected to plastic working that includes hot-pressing
of the sintered body. According to this method, the powder having a
predetermined composition is sintered to obtain an intermediate
form, and then the sintered body is finally, plastically formed. In
this method, the degree of plastic working is made to be
appropriate because not the starting workpiece but the intermediate
shape is plastically formed. In addition, bending and warping of
the sintered body are prevented because the sintered body doe not
have the final shape but only an intermediate shape. By subjecting
the sintered body to the final plastic working, it is possible to
obtain a very thin or fine product having a high dimensional
accuracy and a good shape. The product obtained by this method can
have a sheet thickness of 0.1 mm or more or a diameter of 0.1 mm or
more.
When the rare earth elements other than La and Ce are used, that
is, in the case of the first and second compositions, the weight
ratio of a heavy rare earth element is preferably 0.4 or less, more
preferably 0.2 or less, based on the total weight of the rare earth
elements.
According to the present invention, the coercive force (iHc)
arrives at the highest value at the atomic proportion of La: Ce of
approximately 0.35: approximately 0.65. The highest coercive force
(iHc) is approximately 35 times as high as the composition
containing La alone as the rare earth, and approximately 3.5 times
as high as that containing Ce as the rare earth element.
The present inventors investigated, by the X-ray diffraction
method, the crystal structure of the Fe.sub.78 (La.sub.1-x
Ce.sub.x).sub.17 B.sub.5 alloy explained with reference to FIG. 2
and confirmed the presence of R.sub.2 Fe.sub.14 B type crystal
therein, which has heretofore been identified in the Nd-Fe-B alloy.
La has heretofore been deemed not to form the R.sub.2 Fe.sub.14 B
crystal and has not been used as the main rare earth (R) component.
It was discovered by the present inventors that when La and Ce are
copresent the R.sub.2 Fe.sub.14 B crystal is formed. It is
therefore believed that the R.sub.2 Fe.sub.14 B crystal contributes
to enhancing the coercive force (iHc).
It is known that Ce.sub.2 Fe.sub.14 B forms a tetragonal crystal
with the lattice parameter (a.sub.0)=0.8777, having the coercive
force (iHc) considerably higher than La-Fe-B. The coercive force
(iHc) attained by the copresence of Ce and La according to the
present invention is considerably higher than that of Ce.sub.2
Fe.sub.14 B. Such an enhancement of coercive force (iHc) may be
attributed to the particular proportion of La to Ce present in the
R.sub.2 Fe.sub.14 B crystal. Such proportion appears to be
advantageous from the view points of lattice constant and crystal
anisotropy.
Methods for producing the permanent magnet according to the present
invention are described hereinafter.
The present invention is hereinafter explained with reference to
the examples.
EXAMPLE 1
Ingots having the composition given in Table 1 were produced by a
melting method and then pulverized. Using the obtained powder,
samples in a ribbon form were produced by a melt-rapid cooling
method using a single roll while varying its surfacial speed from
10 to 50 m/sec. The highest coercive force (iHc) obtained by
varying the surfacial speed is given in Table 1.
TABLE 1
__________________________________________________________________________
No. Composition iHc(KOe) Remarks
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.8 (Nd.sub.0.7
Pr.sub.0.3).sub.0.2).sub.0 .17 (Fe.sub.0.93 B.sub.0.07).sub.0.83
8.3 2 ((Ce.sub.0.6 La.sub.0.4).sub.0.8 (Nd.sub.0.7
Pr.sub.0.3).sub.0.2).sub.0 .17 (Fe.sub.0.93 B.sub.0.07).sub.0.83
7.1 3 ((Ce.sub.0.8 La.sub.0.2).sub.0.8 (Nd.sub.0.7
Pr.sub.0.3).sub.0.2).sub.0 .17 (Fe.sub.0.93 B.sub.0.07).sub.0.83
7.2 4 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub.0 .17 (Fe.sub.0.93 B.sub.0.07).sub.0.83
8.3 5 ((Ce.sub.0.7 La.sub.0.3).sub.0.9 (Nd.sub.0.7
Pr.sub.0.3).sub.0.1).sub.0 .17 (Fe.sub.0.93 B.sub.0.07).sub.0.83
7.8 6 (Ce.sub.0.8 (Nd.sub.0.7 Pr.sub.0.3).sub.0.2).sub.0.17
(Fe.sub.0.93 B.sub.0.07).sub.0.83 2.5 Comparative 7 (La.sub.0.8
(Nd.sub.0.7 Pr.sub.0.3).sub.0.2).sub.0.17 (Fe.sub.0.93
B.sub.0.07).sub.0.83 0.7 " 8 (Ce.sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.93 B.sub.0.07).sub.0.83 3.0
" 9 (La.sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub.0.17
(Fe.sub.0.93 B.sub. 0.07).sub.0.83 1.2 " 10 (Ce.sub.0.9 (Nd.sub.0.7
Pr.sub.0.3).sub.0.1).sub.0.17 (Fe.sub.0.93 B.sub.0.07).sub.0.83 2.7
" 11 (La.sub.0.9 (Nd.sub.0.7 Pr.sub.0.3).sub.0.1).sub.0.17
(Fe.sub.0.93 B.sub.0.07).sub.0.83 0.6 "
__________________________________________________________________________
EXAMPLE 2
The raw materials were mixed so that the alloy according to the
present invention, having the composition [(Ce.sub.0.7
La.sub.0.3).sub.0.6 (Nd.sub.0.7 Dy.sub.0.3).sub.0.4 ].sub.0.15
(Fe.sub.0.91 (B.sub.0.09).sub.0.85, and the conventional alloy
having the composition Nd.sub.0.15 (Fe.sub.0.91
B.sub.0.09).sub.0.85, were obtained. The raw materials were melted
in a high-frequency furnace and cast as ingots. The ingots were
pulverized by successively using a jaw-crusher, a Brown mill, and a
jet mill, to obtain powder successively finer in size. Fine powders
5 .mu.m in diameter were finally obtained. The fine powder was
pressed under a magnetic field and then pre-sintered at 950.degree.
C. to obtain a pre-sintered body having the dimension of
20.times.20.times.20 mm. The pre-sintered body was hot-pressed in a
direction parallel to the easy direction of magnetization, using
dies having a dimension of 24.times.24 mm. The conditions for
hot-pressing were: a temperature of 830.degree. C.; a time of 1
hour, and a pressure of 650 kg/cm.sup.2. The plastic workability
and magnetic properties are shown in Table 2.
TABLE 2 ______________________________________ Coercive Maximum
Force Remanence Energy (iHc) (Br) Product Plastic (kOe) (KG) (MGOe)
Workability ______________________________________ Invention 7.0
10.5 23 .circleincircle. Invention 7.0 10.0 21 -- Conventional 12.1
12.3 35 X Conventional 12.1 12.0 35 --
______________________________________
The plastic workability was evaluated by the following four
standards: good ()-working degree of 30% or more; acceptable
()-working degree less than but close to 30%; poor
(.DELTA.)-working degree less than 20%; and, unacceptable
(.times.)-virtually no deformation.
The sintered bodies (without hot-pressing) had a density of 94%
relative to theoretical density.
As is apparent from Table 2, the plastic workability is drastically
enhanced by the replacement of Nd with La and Ce.
EXAMPLE 3
The ingots having the composition as shown in Table 3 were produced
by the melting method. The ingots were crushed into fine pieces.
The fine pieces were melted and then rapidly cooled by the rapid
cooling method used in Example 1.
The coercive force (iHc) of the ribbon is given in Table 3.
TABLE 3
__________________________________________________________________________
Sample Nos. Composition iHc(kOe)
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.99 Al.sub.0.01).sub.0.92
B.sub.0.08).sub.0.83 10.2 2 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.97
Al.sub.0.03).sub.0.92 B.sub.0.08).sub.0.83 12.5 3 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.99 Nb.sub.0.01).sub.0.92 B.sub.0.08).sub.0.83 10.1 4
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.97 Nb.sub.0.03).sub.0.92
B.sub.0.08).sub.0.83 11.5 5 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2). sub.0.3).sub.0.17
((Fe.sub.0.985 Zr.sub.0.015).sub.0.92 B.sub.0.08).su b.0.83 10.1 6
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Mo.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 10.3 7 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.985 Hf.sub.0.015 ).sub.0.92 B.sub.0.08).sub.0.83 9.7 8
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Ag.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 9.7 9 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.985 Ti.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 9.6 10
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985 V.sub.0.015).sub.0.92
B.sub.0.08).sub.0.83 9.5 11 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Ni.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 9.4 12 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.835 Co.sub.0.15 Al.sub.0.015).sub.0.92 B.sub.0.08).sub
.0.83 10.1 13 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.835 Co.sub.0.15
Nb.sub.0.015).sub.0.92 B.sub.0.08).sub .0.83 10.0 14 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
(Fe.sub.0.92 B.sub.0.08).sub.0.83 8.3 15 ((Ce.sub.0.7 La.sub.0.3
).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83 7.0 16 ((Ce.sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 3.0 Comparative 17 ((La.sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83 1.2
__________________________________________________________________________
EXAMPLE 4
The ingots having the composition as shown in Table 4 were produced
by the melting method. The ingots were crushed into fine pieces.
The fine pieces were melted and then rapidly cooled by the rapid
cooling method used in Example 1.
The obtained powder was surface-treated and was mixed with a binder
at a weight proportion of from 1:0.02.about.0.4. The mixture was
compression-formed in the presence of a magnetic field of 10 kOe,
and then the binder was solidified.
The magnetic properties of the bonded magnet are shown in Table
4.
TABLE 4
__________________________________________________________________________
Properties Sample Br Hc (BH)max Nos. Composition (KG) (kOe) (MGOe)
Remarks
__________________________________________________________________________
1 (Ce.sub.0.7 La.sub.0.3).sub.0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 4.4 6.5 4.2 2 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 4.9 8.5 5.5 3 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Al.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 4.7 11.0 5.1 4
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Nb.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 4.9 10.5 5.2 5
(Ce.sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 3.5 3.0 1.8 Comparative 6 (La.sub.0.7
(Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 2.0 1.2 0.7
__________________________________________________________________________
EXAMPLE 5
The raw materials were mixed to provide the composition as given in
Table 5 and then melted by a high frequency furnace in an argon
atmosphere. The melt was cast and the obtained ingots were finely
crushed to obtain powder having particles from 3 to 10 .mu.m in
size. The powder was compression formed in the presence of a
magnetic field of approximately 10 kOe, to obtain oriented green
compacts. The green compacts were sintered at a temperature of from
950.degree. to 1150.degree. C. for approximately 2 hours under
vacuum, followed by cooling. The sintered bodies were aged, while
lowering the temperature from 950.degree. C. down to 350.degree. C.
The sintered bodies were then crushed to obtain powder having
particles from 10 to 200 .mu.m in size. The powder was subjected to
stress relief annealing. The powder was mixed with a binder at a
weight proportion of from 1:0.02.about.0.4. The mixture was
compression-formed in the presence of a magnetic field of 10 kOe,
and the binder was then solidified.
The magnetic properties of the bonded magnet are shown in Table
5.
TABLE 5
__________________________________________________________________________
Properties of Magnet Sample iHc Br (BH)max Nos. Composition (kOe)
(KG) (MGOe) Remarks
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.55 Pr.sub.0.1
Dy.sub.0.35) .sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83
6.8 5.4 5.8 2 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65
Pr.sub.0.15 Dy.sub.0.2) .sub.0.3).sub.0.17 ((Fe.sub.0.985
Al.sub.0.015).sub.0.92 B.sub.0.08). sub.0.83 5.5 5.9 6.9 3
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.2) .sub.0.3).sub.0.17 ((Fe.sub.0.985
Nb.sub.0.015).sub.0.92 B.sub.0.08). sub.0.83 4.6 5.6 6.2 4
((Ce.sub.0.7 La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.2) .sub.0.5).sub.0.17 ((Fe.sub.0.97 Al.sub.0.015
Nb.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 8.5 6.5 7.8 5
((Ce.sub.0.7 La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.2) .sub.0.5).sub.0.17 (Fe.sub.0.835 Co.sub.0.015
Al.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 7.3 6.3 7.9 6
(Ce.sub.0.7 (Nd.sub.0.65 Pr.sub.0.2 Dy.sub.0.15).sub.0.3).sub.0.17
(Fe.sub.0.92 B.sub.0.08).sub.0.83 2.0 3.0 1.5 Comparative 7
(La.sub.0.7 (Nd.sub.0.65 Pr.sub.0.2 Dy.sub.0.15).sub.0.3).sub.0.17
(Fe.sub.0.92 B.sub.0.08).sub.0.83 0.4 1.5 0.2
__________________________________________________________________________
EXAMPLE 6
The ribbons having the composition given in Table 6 were produced
by the process essentially the same as used in Example 1. The
temperature coefficient of remanence (Br) was measured.
The results are given in Table 6. As is understood from Table 6, Co
improves the temperature characteristic of remanence (Br).
TABLE 6
__________________________________________________________________________
Sample Temperature Coefficient Nos. Composition of Br
(%/.degree.C.)
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.985
Al.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 -0.15 2 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.985 Nb.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 -0.15 3
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub. 0.17 ((Fe.sub.0.835 Co.sub.0.15
Al.sub.0.015).sub.0.92 B.sub.0.08).sub .0.83 -0.10 4 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub. 0.17
((Fe.sub.0.835 Co.sub.0.15 Al.sub.0.015).sub.0.92 B.sub.0.08).sub
.0.83 -0.10
__________________________________________________________________________
EXAMPLE 7
The ingots having the composition as given in Table 7 were
produced, followed by rough and then fine crushing to obtain fine
powder having particles from approximately 3 to 6 .mu.m in size.
The powder was then compression molded in the presence of a
magnetic field of approximately 10 kOe and at a pressure of 1.5
ton/cm.sup.2. The obtained green compacts were sintered at a
temperature of from 1000.degree. C. to 1100.degree. C. for 2 hours.
The sintered bodies were aged at 500.degree. C.-900.degree. C. The
magnetic properties of the produced magnets are given in Table
7.
TABLE 7
__________________________________________________________________________
Sample iHc Br (BH)max Nos. Composition (kOe) (KG) (MGOe) Remarks
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.2
Dy.sub.0.15) .sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83
4.5 8.8 16.0 2 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.5
Pr.sub.0.1 Dy.sub.0.4).s ub.0.3).sub.0.17 (Fe.sub.0.92
Al.sub.0.08).sub.0.83 9.0 7.7 14.9 3 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.3).sub.0.17 ((Fe.sub.0.99 Al.sub.0.01).sub.0.92
B.sub.0.08).su b.0.83 6.0 8.5 17.0 4 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.3).sub.0.17 ((Fe.sub.0.97 Al.sub.0.03).sub.0.92
B.sub.0.08).su b.0.83 7.1 7.8 15.0 5 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.3).sub.0.17 ((Fe.sub.0.99 Nb.sub.0.01).sub.0.92
B.sub.0.08).su b.0.83 5.0 8.7 15.1 6 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.3).sub.0.17 ((Fe.sub.0.97 Nb.sub. 0.03).sub.0.92
B.sub.0.08).s ub.0.83 6.0 7.8 15.3 7 ((Ce.sub.0.7
La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.5).sub.0.17 ((Fe.sub.0.99 Al.sub.0.01).sub.0.92
B.sub.0.08).su b.0.83 9.0 9.8 21.7 8 ((Ce.sub.0.7
La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.5).sub.0.17 ((Fe.sub.0.97 Al.sub.0.03).sub.0.92
B.sub.0.08).su b.0.83 11.0 8.6 16.2 9 ((Ce.sub.0.7
La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.5).sub.0.17 ((Fe.sub.0.99 Nb.sub.0.01).sub.0.92
B.sub.0.08).su b.0.83 8.1 9.7 21.5 10 ((Ce.sub.0.7
La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.5).sub.0.17 ((Fe.sub.0.97 Nb.sub.0.03).sub.0.92
B.sub.0.08).su b.0.83 10.2 8.7 16.0 11 ((Ce.sub.0.7
La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2)
.sub.0.3).sub.0.17 ((Fe.sub.0.97 Al.sub.0.015
Nb.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 6.5 8.5 17.0 12
((Ce.sub.0.7 La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.2) .sub.0.5).sub.0.17 ((Fe.sub.0.97 Al.sub.0.015
Nb.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 11.7 9.7 22 13
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.2
Tb.sub.0.15) .sub.0.3).sub.0.17 ((Fe.sub.0.985
Al.sub.0.015).sub.0.92 B.sub.0.08). sub.0.83 5.0 8.5 15.0 14
((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.20 ).sub.0.3).sub.0.17 ((Fe.sub.0.835 Co.sub.0.15
Al.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 6.5 8.1 15.5 15
((Ce.sub.0.7 La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.20 ).sub.0.5).sub.0.17 ((Fe.sub.0.835 Co.sub.0.15
Al.sub.0.015).sub.0.92 B.sub.0.08).sub.0.83 9.9 9.1 19.8 16
((Ce.sub.0.7 (Nd.sub.0.7 Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92
B.sub.0.08).sub.0.83 2.1 4 1 17 ((La.sub.0.7 (Nd.sub.0.7
Pr.sub.0.3).sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83 0.5
2 0.2 18 ((Ce.sub.0.7 (Nd.sub.0.65 Pr.sub.0.2
Dy.sub.0.15).sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83
2.8 4.5 2 Comparative 19 ((La.sub.0.7 (Nd.sub.0.65 Pr.sub.0.2
Dy.sub.0.15).sub.0.3).sub.0.17 (Fe.sub.0.92 B.sub.0.08).sub.0.83
0.7 2.1 0.2
__________________________________________________________________________
EXAMPLE 8
The ribbons having the composition given in Table 8 were produced
by the process which was essentially the same as used in Example 7.
The temperature coefficient of remanence (Br) was measured.
The results are given in Table 8. As is understood from Table 8, Co
improves the temperature characteristic of remanence (Br).
TABLE 8
__________________________________________________________________________
Temperature Coefficient No. Composition of Br (%/.degree.C.)
__________________________________________________________________________
1 ((Ce.sub.0.7 La.sub.0.3).sub.0.7 (Nd.sub.0.65 Pr.sub.0.15
Dy.sub.0.2).s ub.0.3).sub.0.17 ((Fe.sub.0.985
Al.sub.0.015).sub.0.92 B.sub.0.08).sub. 0.83 -0.14 2 ((Ce.sub.0.7
La.sub.0.3).sub.0.5 (Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2).s
ub.0.5).sub.0.17 ((Fe.sub.0.985 Al.sub.0.015).sub.0.92
B.sub.0.08).sub. 0.83 -0.14 3 ((Ce.sub.0.7 La.sub.0.3).sub.0.7
(Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2).s ub.0.3).sub.0.17
((Fe.sub.0.835 Co.sub.0.15 Al.sub.0.015).sub.0.92
B.sub.0.08).sub.0.83 -0.10 4 ((Ce.sub.0.7 La.sub.0.3).sub.0.5
(Nd.sub.0.65 Pr.sub.0.15 Dy.sub.0.2).s ub.0.5).sub.0.17
((Fe.sub.0.835 Co.sub.0.15 Al.sub.0.015).sub.0.92
B.sub.0.08).sub.0.83 -0.10
__________________________________________________________________________
* * * * *