U.S. patent application number 11/059307 was filed with the patent office on 2006-01-05 for fe-based amorphous alloy ribbon and magnetic core formed thereby.
This patent application is currently assigned to Hitachi Metals, Ltd.. Invention is credited to Masamu Naoe, Yuichi Ogawa, Yoshihito Yoshizawa.
Application Number | 20060000525 11/059307 |
Document ID | / |
Family ID | 35079340 |
Filed Date | 2006-01-05 |
United States Patent
Application |
20060000525 |
Kind Code |
A1 |
Naoe; Masamu ; et
al. |
January 5, 2006 |
Fe-based amorphous alloy ribbon and magnetic core formed
thereby
Abstract
A magnetic core provided with a shape for a transformer by a
cut-lap or step-lap method, which is constituted by an Fe-based
amorphous alloy ribbon having excellent magnetic characteristics,
which is represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cM.sub.x or
Fe.sub.aSi.sub.bB.sub.cC.sub.dM.sub.x wherein M is Cr and/or Ni, a
is 78 to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic
%, x is 0.01 to 5 atomic %, and d is 0.001 to 4 atomic %, (a+b+c+x)
or (a+b+c+d+x) being 100.
Inventors: |
Naoe; Masamu; (Saitama-ken,
JP) ; Ogawa; Yuichi; (Saitama-ken, JP) ;
Yoshizawa; Yoshihito; (Saitama-ken, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
Hitachi Metals, Ltd.
Tokyo
JP
|
Family ID: |
35079340 |
Appl. No.: |
11/059307 |
Filed: |
February 17, 2005 |
Current U.S.
Class: |
148/304 |
Current CPC
Class: |
H01F 3/04 20130101; H01F
3/14 20130101; H01F 1/15308 20130101 |
Class at
Publication: |
148/304 |
International
Class: |
C22C 45/02 20060101
C22C045/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2004 |
JP |
2004-198197 |
Dec 27, 2004 |
JP |
2004-376872 |
Claims
1. An Fe-based amorphous alloy ribbon having excellent magnetic
characteristics, which is represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cM.sub.x, wherein M is Cr and/or Ni, a is 78
to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic %,
and x is 0.01 to 5 atomic %, (a+b+c+x) being 100.
2. The Fe-based amorphous alloy ribbon according to claim 1, having
a saturation magnetic flux density of 1.6 T or more, and a magnetic
flux density of 1.5 T or more in a magnetic field of 80 A/m.
3. The Fe-based amorphous alloy ribbon according to claim 1,
wherein a is 78 to 85 atomic %, b is 0.001 to 3 atomic %, c is 10
to 20 atomic %, and x is 0.02 to 4 atomic %, and wherein said alloy
ribbon has a saturation magnetic flux density of 1.65 T or more,
and a magnetic flux density of 1.6 T or more in a magnetic field of
80 A/m.
4. The Fe-based amorphous alloy ribbon according to claim 1,
wherein said M is Cr, and x is 0.01 to 1 atomic %.
5. The Fe-based amorphous alloy ribbon according to claim 1,
wherein said M is Ni, and x is 0.1 to S atomic %.
6. An Fe-based amorphous alloy ribbon having excellent magnetic
characteristics, which is represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cC.sub.dM.sub.x, wherein M is Cr and/or Ni, a
is 78 to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic
%, d is 0.001 to 4 atomic %, and x is 0.01 to 5 atomic %,
(a+b+c+d+x) being 100.
7. The Fe-based amorphous alloy ribbon according to claim 6, having
a saturation magnetic flux density of 1.6 T or more, and a magnetic
flux density of 1.5 T or more in a magnetic field of 80 A/m.
8. The Fe-based amorphous alloy ribbon according to claim 6,
wherein a is 78 to 85 atomic %, b is 0.001 to 3 atomic %, c is 10
to 20 atomic %, d is 0.01 to 3 atomic %, and x is 0.02 to 4 atomic
%, and wherein said alloy ribbon has a saturation magnetic flux
density of 1.65 T or more, and a magnetic flux density of 1.6 T or
more in a magnetic field of 80 A/m.
9. The Fe-based amorphous alloy ribbon according to claim 6,
wherein said M is Cr, and x is 0.01 to 1 atomic %.
10. The Fe-based amorphous alloy ribbon according to claim 6,
wherein said M is Ni, and x is 0.1 to 5 atomic %.
11. A magnetic core constituted by the Fe-based amorphous alloy
ribbon recited in any one of claims 1 to 10, which is provided with
a shape for a transformer by a cut-lap or step-lap method.
Description
FIELD OF TH INVENTION
[0001] The present invention relates to an Fe-based amorphous alloy
ribbon having excellent magnetic properties, and a magnetic core
constituted by such an Fe-based amorphous alloy ribbon, and
particularly to an Fe-based amorphous alloy ribbon and its magnetic
core usable for various transformers, reactors, noise reduction
parts such as choke coils for active filters, smoothing choke
coils, common-mode choke coils, etc., laser power supplies,
magnetic pulse power parts of accelerators, motors, generators,
etc.
BACKGROUND OF THE INVENTION
[0002] Known as magnetic alloys having high saturation magnetic
flux densities and low core losses used for various transformers
and reactors, noise reduction parts such as choke coils for active
filters, smoothing choke coils, common-mode choke coils and
electromagnetic shields, laser power supplies, magnetic pulse power
parts of accelerators, motors, generators, etc. are silicon steel
and Fe-based amorphous alloys. Though silicon steel has a high
magnetic flux density with low cost, it disadvantageously suffers
from a core loss in high-frequency applications. The Fe-based
amorphous alloys have lower saturation magnetic flux densities than
silicon steel, resulting in a larger magnetic core size. They also
have large magnetostriction, vulnerable to the deterioration of
characteristics due to stress.
[0003] As magnetic core materials for transformers, JP 9-31610 A
discloses a method for producing an amorphous Fe--Si--B-M alloy
ribbon, wherein M represents an inevitable impurity, at least one
selected from the group consisting of Al, Ti, S, Mn and Zr. This
amorphous alloy has a magnetic flux density of 1.4 T or more in a
magnetic field of 80 A/m.
[0004] As a method for improving the core loss of an Fe-based
amorphous alloy, JP 10-324961 A discloses a method for producing an
Fe--Si--B-M amorphous alloy ribbon, wherein M is at least one
selected from the group consisting of Mn, Co, Ni and Cr. In this
method, a heat treatment at a relatively low temperature is carried
out for at least 6 hours or more before a conventional heat
treatment at an intermediate or high temperature in a magnetic
field.
[0005] However, the above conventional Fe-based amorphous alloy
ribbons are not suitable as magnetic core materials for
transformers because of low magnetic flux densities. Because a low
magnetic flux density necessitates a low maximum operation magnetic
flux density, the magnetic core having a low magnetic flux density
inevitably has large volume or weight.
[0006] Though core loss has been investigated on plates obtained
from the above conventional Fe-based amorphous alloy ribbons, no
investigation has been conducted with respect to stress generated
when worked to magnetic cores. Further, because a heat treatment
needs a long period of time in the production method proposed by JP
10-324961, it is extremely poor in mass producibility.
[0007] Because amorphous Fe--Si--B or Fe--Si--B--C alloys have low
crystallization temperatures in compositions suitable for high
saturation magnetic flux densities, the should be heat-treated at
low temperatures. In this case, because stress generated in the
Fe-based amorphous alloys worked to magnetic cores for transformers
is not sufficiently relaxed, the magnetic characteristics of the
Fe-based amorphous alloys are extremely deteriorated.
OBJECT OF THE INVENTION
[0008] Accordingly, an object of the present invention is to
provide an Fe-based amorphous alloy ribbon having improved
saturation magnetic flux density and soft magnetic characteristics,
whose stress is sufficiently relaxed by a heat treatment for a
relatively short period of time.
[0009] Another object of the present invention is to provide a
magnetic core constituted by such an Fe-based amorphous alloy
ribbon.
SUMMARY OF THE INVENTION
[0010] The first Fe-based amorphous alloy ribbon having excellent
magnetic characteristics according to the present invention is
represented by the general formula: Fe.sub.aSi.sub.bB.sub.cM.sub.x,
wherein M is Cr and/or Ni, a is 78 to 86 atomic %, b is 0.001 to 5
atomic %, c is 7 to 20 atomic %, and x is 0.01 to 5 atomic %,
(a+b+C+x) being 100. x is preferably 0.01 to 1 atomic % when M is
Cr, and 0.1 to 5 atomic % when M is Ni. A heat treatment under
predetermined conditions can provide this Fe-based amorphous alloy
ribbon with an improved magnetic flux density and sufficiently
relaxed stress. This Fe-based amorphous alloy ribbon preferably has
a thickness of 25 to 40 .mu.m, a saturation magnetic flux density
of 1.6 T or more, and a magnetic flux density of 1.5 T or more in a
magnetic field of 80 A/m.
[0011] More preferably, a is 78 to 85 atomic %, b is 0.001 to 3
atomic %, c is 10 to 20 atomic %, and x is 0.02 to 4 atomic %, to
provide an Fe-based amorphous alloy ribbon with a further improved
magnetic flux density and sufficiently relaxed stress. This
Fe-based amorphous alloy ribbon has a saturation magnetic flux
density of 1.65 T or more, and a magnetic flux density of 1.6 T or
more in a magnetic field of 80 A/m.
[0012] The second Fe-based amorphous alloy ribbon having excellent
magnetic characteristics according to the present invention is
represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cC.sub.dM.sub.x, wherein M is Cr and/or Ni, a
is 78 to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic
%, d is 0.001 to 4 atomic %, and x is 0.01 to 5 atomic %,
(a+b+c+d+x) being 100. x is preferably 0.01 to 1 atomic % when M is
Cr, and 0.1 to 5 atomic % when M is Ni. A heat treatment under
predetermined conditions can provide this Fe-based amorphous alloy
ribbon with an improved magnetic flux density and sufficiently
relaxed stress. This Fe-based amorphous alloy ribbon preferably has
a thickness of 25 to 40 .mu.m, a saturation magnetic flux density
of 1.6 T or more, and a magnetic flux density of 1.5 T or more in a
magnetic field of 80 A/m.
[0013] More preferably, a is 78 to 85 atomic %, b is 0.001 to 3
atomic %, c is 10 to 20 atomic %, d is 0.01 to 3 atomic %, and x is
0.02 to 4 atomic %, to provide an Fe-based amorphous alloy ribbon
with a further improved magnetic flux density and sufficiently
relaxed stress. This Fe-based amorphous alloy ribbon has a
saturation magnetic flux density of 1.65 T or more, and a magnetic
flux density of 1.6 T or more in a magnetic field of 80 A/m.
[0014] The magnetic core of the present invention is constituted by
either one of the above Fe-based amorphous alloy ribbons by a
cut-lap or step-lap method to have a shape for a transformer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1(a) is a plan view showing one example of a
ring-shaped magnetic core constituted by the Fe-based amorphous
alloy ribbon of the present invention;
[0016] FIG. 1(b) is a cross-sectional view taken along the line A-A
in FIG. 1(a);
[0017] FIG. 2(a) is a plan view showing another example of a
ring-shaped magnetic core constituted by the Fe-based amorphous
alloy ribbon of the present invention;
[0018] FIG. 2(b) is a cross-sectional view taken along the line B-B
in FIG. 2(a);
[0019] FIG. 3(a) is a partially enlarged plan view showing a
ring-shaped magnetic core produced by a cut-lap or step-lap method;
and
[0020] FIG. 3(b) is a cross-sectional view taken along the line C-C
in FIG. 3(a); and
[0021] FIG. 4 is a schematic view showing the method of measuring a
stress relaxation rate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[1] Composition
[0022] The first Fe-based amorphous alloy of the present invention
is represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cM.sub.x, wherein M is Cr and/or Ni, a is 78
to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic %,
and x is 0.01 to 5 atomic %, (a+b+c+x) being 100.
[0023] The second Fe-based amorphous alloy of the present invention
is represented by the general formula:
Fe.sub.aSi.sub.bB.sub.cC.sub.dM.sub.x, wherein M is Cr and/or Ni, a
is 78 to 86 atomic %, b is 0.001 to 5 atomic %, c is 7 to 20 atomic
%, d is 0.001 to 4 atomic %, and x is 0.01 to 5 atomic %,
(a+b+c+d+x) being 100.
[0024] When the Fe-based amorphous alloy of the present invention
containing Cr and/or Ni is used, stress generated at the time of
producing a magnetic core is sufficiently relaxed by a heat
treatment. Cr functions to provide the alloy with a reduced melt
viscosity, and improved wettability with a roll and surface
conditions. Cr and Ni also have an effect of accelerating the
relaxation of stress in the Fe-based amorphous alloy at the time of
a heat treatment, thereby improving its soft magnetic
characteristics. However, sufficient effects cannot be obtained
when too small amounts of Cr and/or Ni are contained, and there is
remarkable deterioration in a Curie temperature and a saturation
magnetic flux density when their amounts are excessive.
Accordingly, the amount of Cr and/or Ni is 0.01 to 5 atomic %,
preferably 0.02 to 4 atomic %, more preferably 0.1 to 4 atomic %,
based on 100 atomic % of the main composition (a+b+c+x or
a+b+c+d+x) of the alloy.
[0025] When M is Cr, the range of x is preferably 0.01 to 1 atomic
%, more preferably 0.02 to 0.5 atomic %. When M is Ni, the range of
x is preferably 0.1 to 5 atomic %, more preferably 0.3 to 4 atomic
%. There is thus difference between Cr and Ni in a necessary
amount. Cr is effective in a small amount to relax stress generated
during working to a magnetic core, while Ni is effective in a
larger amount than that of Cr to relax stress generated during
working to a magnetic core. Cr and Ni may be properly selected
depending on the required magnetic properties and stress relaxation
rate.
[0026] Si is an element important to make the alloy amorphous and
necessary to keep the Curie temperature of the alloy high to some
extent. When the amount of Si is too small, the Curie temperature
of the alloy is too low for practical applications. On the other
hand, when its amount is too much, the core loss of the alloy is
increased, and the percentages of Fe and/or B in the alloy are
reduced, resulting in lowered magnetic flux density and thermal
stability. Accordingly, the amount of Si is 0.001 to 5 atomic %,
preferably 0.001 to 3 atomic %, based on 100 atomic % of the main
composition of the alloy.
[0027] B is an important element for making the alloy amorphous.
When the amount of B is too small, the alloy is not easily made
amorphous, resulting in reduced soft magnetic characteristics and
increased core loss. On the other hand, when the amount of B is too
much, the percentages of Fe and/or Si in the alloy are reduced,
resulting in lowered magnetic flux density and thermal stability.
Accordingly, the amount of B is 7 to 20 atomic %, preferably 10 to
20 atomic %, based on 100 atomic % of the main composition of the
alloy.
[0028] C is effective to lower the melt viscosity of the alloy and
improve wettability with a roll. However, too much C leads to the
deterioration of magnetic characteristics by aging. Thus, the
amount of C is 0.001 to 4 atomic %, preferably 0.01 to 3 atomic %,
more preferably 0.1 to 3 atomic %, based on 100 atomic % of the
main composition of the alloy.
[0029] The balance is substantially Fe, which is an important
element to obtain a high magnetic flux density. However, too much
Fe leads to an increased core loss and deteriorated thermal
stability. Thus, the amount of Fe is 78 to 86 atomic %, preferably
78 to 85 atomic %, based on 100 atomic % of the main composition of
the alloy.
[0030] The Fe-based amorphous alloy of the present invention may
contain at least one of Mn, P, S, Cu, Al, Sn, Pb, Ca, Ti and Zr as
an inevitable impurity in an amount of about 0.0002 to 0.2 atomic %
based on 100 atomic % of the main composition of the above
alloy.
[2] Production Method
[0031] The Fe-based amorphous alloy of the present invention is
obtained by rapidly quenching a melt of the above composition by
single roll method, etc. and heat-treating the resultant Fe-based
amorphous alloy at a predetermined temperature to relax stress in
the alloy. Though the rapid quenching by a single roll method, etc.
is usually carried out in the air, in an atmosphere of Ar or He, or
in a reduced-pressure atmosphere, it may be carried out in an
atmosphere containing nitrogen, carbon monoxide or carbon dioxide.
Though the heat treatment is usually carried out in an inert gas
atmosphere of Ar, He, N.sub.2, etc. or in vacuum, it may be carried
out in the air.
[0032] The heat treatment is carried out desirably in an inert gas
atmosphere usually having a dew point of -30.degree. C. or lower.
The heat treatment in an inert gas atmosphere having a dew point of
-60.degree. C. or lower is more preferable because of small
unevenness in the heat-treated ribbon. In the case of a heat
treatment at a constant temperature, the temperature-holding time
is usually 24 hours or less, preferably 4 hours or less, from the
aspect of mass producibility. During the heat treatment, an average
temperature-elevating speed is preferably 0.1-200.degree. C./min,
more preferably 0.1-100.degree. C./min, and the average cooling
speed is preferably 0.1-3000.degree. C./min, more preferably
0.1-100.degree. C./min. The heat treatment in this range can
provide the alloy with a low magnetic core loss. The heat treatment
may be carried out by a single step or multiple steps, or may be
repeated plural times. Further, DC, AC or pulse current may be
supplied to the alloy to generate heat for a heat treatment.
[0033] The Fe-based amorphous alloy ribbon of the present invention
may be coated with (1) a powder or film of SiO.sub.2, MgO,
Al.sub.2O.sub.3, etc., (2) an insulating layer formed by a chemical
conversion treatment, or (3) an insulating oxide layer formed by an
anodic oxidation treatment, for interlayer insulation, if
necessary. These treatments decrease the influence of eddy current
flowing particularly between layers at high frequencies, thereby
reducing a magnetic core loss at high frequencies. These treatments
are particularly effective for magnetic cores constituted by as
wide ribbons as 50 mm or more having good surface conditions.
Further, impregnation, coating, etc. may be conducted in the
production of magnetic cores.
[0034] The Fe-based amorphous alloy ribbon of the present invention
can be worked to rings for magnetic cores 1 for transformers,
motors and generators, etc. as shown in FIGS. 1 and 2. The Fe-based
amorphous alloy ribbon 10 of the present invention is suitably
formed to transformer shapes by a cut-lap or a step-lap method to
provide magnetic cores.
[0035] The present invention will be described referring to
Examples below without intention of limiting the present invention
thereto.
EXAMPLE 1
[0036] Alloy melts having compositions represented by
Fe.sub.aSi.sub.bB.sub.cM.sub.x (a+b+c+x=100) as shown in Table 1
were rapidly quenched by a single roll method to produce amorphous
alloy ribbons of 5 mm in width and 25 .mu.m in thickness.
[0037] Each Fe-based amorphous alloy ribbon was wound to form a
toroidal magnetic core of 19 mm in outer diameter and 15 mm in
inner diameter, which was heat-treated in an Ar gas atmosphere.
During the heat treatment, a magnetic field of 1 kA/m was applied
in a direction aligned with the magnetic path of the core, and the
temperature was elevated to an optimum heat-treating temperature
between 320.degree. C. and 370.degree. C., at which the highest
saturation magnetic flux density and other soft magnetic properties
were obtained, over 2 hours, kept at each heat-treating temperature
for 1 hour, and then cooled to 200.degree. C. over 1 hour. The
heat-treated ribbons were mostly amorphous. The resultant toroidal
magnetic cores were measured with respect to a saturation magnetic
flux density Bs, a magnetic flux density B.sub.80 in a magnetic
field of 80 A/m, a core loss W.sub.13/50 in a magnetic flux density
of 1.3 T at a frequency of 50 Hz, and core loss W.sub.14/50 in a
magnetic flux density of 1.4 T at a frequency of 50 Hz.
[0038] As shown in FIG. 4, each Fe-based amorphous alloy ribbon 10
cut to a length of 10.5 (.pi.R.sub.0) cm was wound around a quartz
pipe 11 having a diameter of R.sub.0 cm to form a single-plate
sample and heat-treated under the same conditions as above to relax
stress during working to a ring. A diameter R.sub.1 of a circle
corresponding to the C-shaped sample 10' freed from the quartz pipe
11 was measured to determine a stress relaxation rate Rs expressed
by the formula: Rs=(R.sub.0/R.sub.1).times.100 [%], as a parameter
expressing to which extent stress is relaxed by the annealing (heat
treatment). The stress relaxation rate Rs of 100% means that the
stress is completely relaxed.
[0039] The results are shown in Table 1. TABLE-US-00001 TABLE 1
Sample Bs B.sub.80 W.sub.13/50 W.sub.14/50 Rs No. Composition [T]
[T] [W/kg] [W/kg] [%] 1-1 Fe.sub.82Si.sub.2B.sub.15.95Cr.sub.0.05
1.64 1.62 0.27 0.35 92.5 1-2 Fe.sub.82Si.sub.2B.sub.15.9Cr.sub.0.1
1.64 1.63 0.20 0.26 95.7 1-3 Fe.sub.82Si.sub.2B.sub.15.5Cr.sub.0.5
1.62 1.51 0.20 0.24 98.8 1-4 Fe.sub.82Si.sub.2B.sub.15Cr.sub.1 1.60
1.50 0.24 0.30 99.0 1-5 Fe.sub.82Si.sub.2B.sub.15.98Ni.sub.0.02
1.64 1.60 0.28 0.36 92.3 1-6 Fe.sub.82Si.sub.2B.sub.15.9Ni.sub.0.1
1.64 1.57 0.21 0.28 95.1 1-7 Fe.sub.82Si.sub.2B.sub.15.5Ni.sub.0.5
1.63 1.57 0.21 0.29 97.0 1-8 Fe.sub.82Si.sub.2B.sub.15Ni.sub.1 1.60
1.54 0.25 0.33 97.2 1-9
Fe.sub.82Si.sub.2B.sub.15.8Cr.sub.01Ni.sub.0.1 1.62 1.58 0.27 0.37
93.1 1-10 Fe.sub.82Si.sub.2B.sub.15.5Cr.sub.03Ni.sub.0.2 1.61 1.56
0.23 0.31 95.2 1-11 Fe.sub.82Si.sub.2B.sub.15Cr.sub.05Ni.sub.0.5
1.60 1.52 0.25 0.33 97.3 1-12
Fe.sub.83.9Si.sub.0.1B.sub.15.9Cr.sub.0.1 1.63 1.61 0.31 0.44 94.4
1-13 Fe.sub.83Si.sub.1B.sub.15.9Cr.sub.0.1 1.64 1.62 0.22 0.29 94.7
1-14 Fe.sub.81Si.sub.3B.sub.15.9Cr.sub.0.1 1.62 1.60 0.22 0.27 95.1
1-15 Fe.sub.83.9Si.sub.2B.sub.14Cr.sub.0.1 1.64 1.63 0.21 0.26 96.0
1-16 Fe.sub.80.9Si.sub.2B.sub.17Cr.sub.0.1 1.61 1.56 0.22 0.29 95.6
1-17 Fe.sub.81 5Si.sub.0.01B.sub.17.99Ni.sub.0.5 1.68 1.65 0.28
0.37 92.1 1-18 Fe.sub.80Si.sub.0.01B.sub.17.99Ni.sub.2 1.68 1.66
0.30 0.35 92.5 1-19 Fe.sub.77Si.sub.0.01B.sub.17.99Ni.sub.5 1.65
1.63 0.32 0.35 93.3 1-20 Fe.sub.81.5Si.sub.1B.sub.17Ni.sub.0.5 1.67
1.65 0.29 0.35 93.4 1-21 Fe.sub.80Si.sub.1B.sub.17Ni.sub.2 1.67
1.65 0.29 0.36 93.3 1-22 Fe.sub.77Si.sub.1B.sub.17Ni.sub.5 1.65
1.63 0.31 0.38 95.6 1-23 Fe.sub.81.5Si.sub.2B.sub.16Ni.sub.0.5 1.68
1.65 0.25 0.31 93.0 1-24 Fe.sub.80Si.sub.2B.sub.16Ni.sub.2 1.67
1.65 0.24 0.29 93.2 1-25 Fe.sub.77Si.sub.2B.sub.16Ni.sub.5 1.65
1.62 0.28 0.37 93.1 1-26* Fe.sub.82Si.sub.0.01B.sub.17.99 1.64 1.63
0.38 0.49 90.2 1-27* Fe.sub.82Si.sub.1B.sub.17 1.64 1.63 0.35 0.48
91.3 1-28* Fe.sub.82Si.sub.2B.sub.16 1.64 1.62 0.30 0.41 92.2 1-29*
Fe.sub.72Si.sub.0.01B.sub.17.99Ni.sub.10 1.58 1.57 -- -- -- 1-30*
Fe.sub.72Si.sub.1B.sub.17Ni.sub.10 1.58 1.55 -- -- -- 1-31*
Fe.sub.72Si.sub.2B.sub.16Ni.sub.10 1.64 1.61 0.35 0.51 89.9 1-32*
Fe.sub.82Si.sub.2B.sub.10Cr.sub.6 1.55 1.49 -- -- -- 1-33*
Fe.sub.82Si.sub.2B.sub.10Ni.sub.6 1.58 1.48 -- -- -- 1-34*
Fe.sub.82Si.sub.2B.sub.6Cr.sub.5Ni.sub.5 1.51 1.45 -- -- -- 1-35*
Fe.sub.79Si.sub.6B.sub.15.95Cr.sub.0.05 1.58 1.55 -- -- -- 1-36*
Fe.sub.76Si.sub.8B.sub.15.95Cr.sub.0.05 1.52 1.45 -- -- -- 1-37*
Fe.sub.84.9Si.sub.10B.sub.5Cr.sub.0.1 1.61 1.57 0.39 0.59 92.4
1-38* Fe.sub.75.9Si.sub.2B.sub.22Cr.sub.0.1 1.50 1.45 -- -- --
Note: *A sample outside the present invention.
[0040] It is clear from Table 1 that Samples 1-1 to 1-25 have
larger stress relaxation rates Rs than those of Samples 1-26 to
1-28, 1-31 and 1-37, so that their stress generated when worked to
rings was sufficiently relaxed. More improvement was obtained in
Samples 1-1 to 1-25 than in Samples 1-26 to 1-38 with respect to
the core losses W.sub.13/50 and W.sub.14/50.
[0041] When an alloy having a low magnetic flux density is used at
an operating magnetic flux density of 1.3 T or more, it suffers
from an extremely large core loss, for instance, W.sub.14/50,
unsuitable as a magnetic core material. However, because the
Fe-based amorphous alloy ribbon of the present invention has as
high a saturation magnetic flux density as 1.6 T or more, its
operating magnetic flux density can be increased to 1.4 T, so that
its core loss W.sub.14/50 is so small that the magnetic core can
withstand practical applications.
[0042] Accordingly, the Fe-based amorphous alloy ribbon of the
present invention can provide smaller and higher-performance
magnetic cores than conventional ones.
EXAMPLE 2
[0043] 20 Samples 2-1 to 2-11 and 2-12 to 2-16 of various
compositions were produced and heat-treated in the same manner as
in Example 1. The core loss increase ratio Wr of each resultant
Fe-based amorphous alloy ribbon is shown in Table 2 together with a
composition, a heat treatment temperature, a saturation magnetic
flux density Bs, a stress relaxation rate Rs, an average surface
roughness Ra, and a space factor. The saturation magnetic flux
density Bs and the stress relaxation rate Rs were measured in the
same manner as in Example 1.
[0044] The core loss increase ratio Wr is a parameter expressing an
increase ratio of the core loss when the operating magnetic flux
density increases from 1.3 T to 1.4 T, which is represented by the
following equation:
Wr=(W.sub.14/50-W.sub.13/50)/W.sub.13/50.times.100 [%] (2), wherein
W.sub.13/50 represents a core loss at a magnetic flux density of
1.3 T and a frequency of 50 Hz, and W.sub.14/50 represents a core
loss at a magnetic flux density of 1.4 T and a frequency of 50 Hz.
In Sample 2-12, stress generated when worked to a toroidal magnetic
core was not sufficiently relaxed, and its saturation magnetic flux
density was small. Accordingly, it had drastically increased core
loss with large Wr at an operating magnetic flux density of 1.4 T.
Though Sample 2-13 had a high saturation magnetic flux density, it
had large Wr because of a low relaxation rate of stress generated
when worked to a toroidal magnetic core. Because Samples 2-1 to
2-11 containing proper amounts of Cr or Ni had stress sufficiently
relaxed by a heat treatment, and high saturation magnetic flux
density, their core loss increase ratios Wr were smaller than those
of Samples 2-12 and 2-13.
[0045] To measure surface roughness, each Fe-based amorphous alloy
ribbon was cut to a rectangular shape of 5 mm in width, 25 .mu.m in
thickness and 12 cm in length, and heat-treated in the same manner
as above. The measured surface roughness was arithmetically
averaged in a width direction of the ribbon. The space factor of a
magnetic core constituted by each Fe-based amorphous alloy ribbon
was further measured. In general, the smaller the surface roughness
Ra, the larger the space factor of the magnetic core. The addition
of Cr and/or Ni in proper amounts serves to reduce the melt
viscosity of the alloy, thereby making a roll well wettable by the
alloy melt. Accordingly, the resultant amorphous alloy ribbon has a
smoother surface than those of conventional amorphous alloy ribbons
containing no Cr or Ni. The Fe-based amorphous alloy ribbon with a
smoother surface provides a magnetic core with a larger space
factor, thereby making the magnetic core smaller and lighter in
weight. TABLE-US-00002 TABLE 2 Sample Bs Wr Rs Ra.sup.(1) Space No.
Composition [T] [%] [%] [.mu.m] Factor [%] 2-1
Fe.sub.82Si.sub.2B.sub.15.95Cr.sub.0.05 1.64 29.6 92.5 0.28 87 2-2
Fe.sub.82Si.sub.2B.sub.15.9Cr.sub.0.1 1.64 30.0 95.7 0.28 88 2-3
Fe.sub.82Si.sub.2B.sub.15.5Cr.sub.0.5 1.62 20.0 98.8 0.26 87 2-4
Fe.sub.83.9Si.sub.2B.sub.14Cr.sub.0.1 1.64 28.3 96.0 0.31 88 2-5
Fe.sub.80.9Si.sub.2B.sub.17Cr.sub.0.1 1.61 31.8 95.6 0.33 87 2-6
Fe.sub.81.5Si.sub.1B.sub.17Ni.sub.0.5 1.67 20.7 93.4 0.25 91 2-7
Fe.sub.80Si.sub.1B.sub.17Ni.sub.2 1.67 24.1 93.3 0.26 90 2-8
Fe.sub.77Si.sub.1B.sub.17Ni.sub.5 1.65 22.6 95.6 0.41 86 2-9
Fe.sub.81.5Si.sub.2B.sub.16Ni.sub.0.5 1.68 24.0 93.0 0.29 93 2-10
Fe.sub.80Si.sub.2B.sub.16Ni.sub.2 1.67 20.8 93.2 0.23 92 2-11
Fe.sub.77Si.sub.2B.sub.16Ni.sub.5 1.65 32.1 93.1 0.36 89 2-12*
Fe.sub.79Si.sub.9B.sub.12 1.58 32.5 90.1 0.44 86 2-13*
Fe.sub.82Si.sub.2B.sub.16 1.64 36.7 92.2 0.45 85 2-14*
Fe.sub.81.5Si.sub.2B.sub.16Co.sub.0.5 1.68 25.1 94.2 0.25 86 2-15*
Fe.sub.80Si.sub.2B.sub.16Co.sub.2 1.69 23.3 94.3 0.25 87 2-16*
Fe.sub.77Si.sub.2B.sub.16Co.sub.5 1.71 31.2 93.1 0.28 90 Note: *A
sample outside the present invention. .sup.(1)Arithmetically
averaged surface roughness.
[0046] Toroidal magnetic cores produced by ribbons of Samples 2-12
and 2-13 had smaller saturation magnetic flux densities Bs than
those of the single-plate samples of the same composition because
of stress generated when worked to the magnetic cores. On the other
hand, because stress was sufficiently relaxed by a heat treatment
in the toroidal magnetic cores produced by the ribbons of Samples
2-1 to 2-11 within the scope of the present invention, there was
only small decrease in the saturation magnetic flux density, and
their decrease ratios were extremely smaller than those of Samples
2-12 and 2-13.
[0047] When elements for improving core loss and corrosion
resistance are added to the Fe-based amorphous alloy, the magnetic
characteristics of the alloy are generally likely to be
deteriorated. However, the Fe-based amorphous alloy ribbons of the
present invention containing proper amounts of Cr and/or Ni
effective for stress relaxation have comparable saturation magnetic
flux densities to those of the alloys containing neither Cr nor Ni.
Accordingly, the Fe-based amorphous alloy ribbons of the present
invention have excellent magnetic characteristics, suitable for
magnetic cores for transformers, because stress generated during
producing magnetic cores is sufficiently relaxed.
[0048] As well known, the addition of Co increases the saturation
magnetic flux density of the Fe-based amorphous alloy. Samples 2-14
to 2-16 containing Co had large saturation magnetic flux density
and space factor. However, the addition of Co increases the cost of
the Fe-based amorphous alloy because Co is a rare metal. On the
other hand, Ni and Cr are less expensive than Co. If Ni or Cr is
added in a proper amount, the Fe-based amorphous alloy is provided
with improved magnetic flux density and space factor as in the
addition of Co. Accordingly, the addition of Ni and/or Cr in proper
amounts is effective to provide the Fe-based amorphous alloy ribbon
with sufficiently relaxed stress and excellent magnetic properties,
which enables the production of small, lightweight magnetic
cores.
EXAMPLE 3
[0049] Alloy melts having compositions represented by
Fe.sub.aSi.sub.bB.sub.cC.sub.dM.sub.x (a+b+c+d+x=100) as shown in
Table 3 were rapidly quenched by a single roll method, to form
Fe-based amorphous alloy ribbons of 5 mm in width and 25 .mu.m in
thickness. Each of the resultant Fe-based amorphous alloy ribbons
was wound to form a toroidal magnetic core of 19 mm in outer
diameter and 15 mm in inner diameter, and heat-treated in the same
manner as in Example 1. The heat-treated alloys were mostly
amorphous.
[0050] Each Sample was measured in the same manner as in Example 1
with respect to a saturation magnetic flux density Bs, a magnetic
flux density B80 in a magnetic field of 80 A/m, a core loss
W.sub.13/50 at a magnetic flux density of 1.3 T and a frequency of
50 Hz, a core loss W.sub.14/50 at a magnetic flux density of 1.4 T
and a frequency of 50 Hz, and a stress relaxation rate Rs. The
results are shown in Table 3. TABLE-US-00003 TABLE 3 Sam- ple Bs
B.sub.80 W.sub.13/50 W.sub.14/50 Rs No. Composition [T] [T] [W/kg]
[W/kg] [%] 3-1 Fe.sub.82Si.sub.2B.sub.13.95C.sub.2Cr.sub.0.05 1.64
1.61 0.28 0.38 95.2 3-2
Fe.sub.82Si.sub.2B.sub.13.9C.sub.2Cr.sub.0.1 1.64 1.61 0.20 0.23
97.2 3-3 Fe.sub.82Si.sub.2B.sub.13.5C.sub.2Cr.sub.0.5 1.63 1.60
0.21 0.25 99.5 3-4 Fe.sub.82Si.sub.2B.sub.13C.sub.2Cr.sub.1 1.62
1.54 0.25 0.30 99.2 3-5
Fe.sub.82Si.sub.2B.sub.13.98C.sub.2Ni.sub.0.02 1.64 1.61 0.28 0.38
95.0 3-6 Fe.sub.82Si.sub.2B.sub.13.9C.sub.2Ni.sub.0.1 1.63 1.59
0.23 0.29 95.1 3-7 Fe.sub.82Si.sub.2B.sub.13.5C.sub.2Ni.sub.0.5
1.63 1.57 0.26 0.30 98.3 3-8
Fe.sub.82Si.sub.2B.sub.13C.sub.2Ni.sub.1 1.62 1.55 0.27 0.33 99.0
3-9 Fe.sub.81.5Si.sub.2B.sub.14C.sub.2Ni.sub.0.5 1.67 1.63 0.28
0.31 94.9 3-10 Fe.sub.80Si.sub.2B.sub.14C.sub.2Ni.sub.2 1.67 1.64
0.25 0.31 95.1 3-11 Fe.sub.77Si.sub.2B.sub.14C.sub.2Ni.sub.5 1.66
1.63 0.27 0.35 95.0 3-12
Fe.sub.82Si.sub.2B.sub.13.8C.sub.2Cr.sub.0.1Ni.sub.01 1.63 1.61
0.23 0.28 93.0 3-13
Fe.sub.82Si.sub.2B.sub.13.5C.sub.2Cr.sub.0.3Ni.sub.02 1.63 1.60
0.25 0.30 96.3 3-14
Fe.sub.82Si.sub.2B.sub.13C.sub.2Cr.sub.0.5Ni.sub.05 1.60 1.57 0.28
0.35 97.3 3-15 Fe.sub.83.9Si.sub.0.1B.sub.13.9C.sub.2Cr.sub.0.1
1.64 1.60 0.35 0.47 94.5 3-16
Fe.sub.83Si.sub.1B.sub.13.9C.sub.2Cr.sub.0.1 1.63 1.61 0.23 0.28
96.8 3-17 Fe.sub.81Si.sub.3B.sub.13.9C.sub.2Cr.sub.0.1 1.62 1.61
0.24 0.27 97.1 3-18 Fe.sub.80.9Si.sub.2B.sub.15C.sub.2Cr.sub.0.1
1.61 1.53 0.25 0.31 96.8 3-19
Fe.sub.78.9Si.sub.2B.sub.17C.sub.2Cr.sub.0.1 1.60 1.52 0.26 0.32
95.4 3-20* Fe.sub.82Si.sub.2B.sub.14C.sub.2 1.65 1.63 0.29 0.39
94.9 3-21* Fe.sub.79Si.sub.2B.sub.11C.sub.2Cr.sub.6 1.54 1.48 -- --
-- 3-22* Fe.sub.79Si.sub.2B.sub.11C.sub.2Ni.sub.6 1.51 1.45 -- --
-- 3-23* Fe.sub.76Si.sub.2B.sub.10C.sub.2Cr.sub.5Ni.sub.5 1.50 1.39
-- -- -- 3-24* Fe.sub.77Si.sub.5B.sub.17.87C.sub.0.08Cr.sub.0.05
1.57 1.45 -- -- -- 3-25*
Fe.sub.77Si.sub.5B.sub.14.95C.sub.3Cr.sub.0.05 1.58 1.46 -- -- --
3-26* Fe.sub.77Si.sub.5B.sub.11.95C.sub.6Cr.sub.0.05 1.52 1.45 --
-- -- 3-27* Fe.sub.76Si.sub.8B.sub.13.9C.sub.2Cr.sub.0.1 1.52 1.44
-- -- -- 3-28* Fe.sub.82.9Si.sub.10B.sub.5C.sub.2Cr.sub.0.1 1.62
1.60 0.29 0.42 94.6 3-29*
Fe.sub.73.9Si.sub.2B.sub.22C.sub.2Cr.sub.0.1 1.51 1.44 -- -- --
Note: *A sample outside the present invention.
[0051] It is clear from Table 3 that Samples 3-1 to 3-19 had
improved core losses W.sub.13/50 and W.sub.14/50 than those of
Samples 3-21 to 3-29.
EXAMPLE 4
[0052] The same alloy melts as in Examples 1 to 3 were rapidly
quenched by a single roll method, to obtain Fe-based amorphous
alloy ribbons of 25 .mu.m in thickness and 50 mm in width. Each
ribbon was wound to a toroidal magnetic core of 19 mm in outer
diameter and 15 mm in inner diameter for a transformer by a cut-lap
or step-lap method, and heat-treated in the same manner as in
Example 1. Because proper amounts of Cr and/or Ni were contained in
the amorphous alloys, stress generated when worked to rings was
sufficiently relaxed by the heat treatment, resulting in magnetic
cores for transformers having narrow gaps and excellent magnetic
characteristics.
[0053] The Fe-based amorphous alloy ribbons of the present
invention having high saturation magnetic flux densities and low
magnetic core losses are usable for power transformers and
reactors, noise reduction parts such as choke coils for active
filters, smoothing choke coils, common-mode choke coils,
electromagnetic shields, etc., laser power supplies, parts for
pulse power circuits of accelerators, motors, generators, etc.
Because stress is sufficiently relaxed by a heat treatment for a
relatively short period of time in the Fe-based amorphous alloy
ribbons of the present invention, which contain proper amounts of
Cr and/or Ni, they are suitable for mass production. Particularly
in magnetic cores for power source transformers worked by a cut-lap
or step-lap method as shown in FIG. 3, the deterioration of
magnetic characteristics and magnetic core losses can be made
extremely small.
[0054] The addition of Cr and/or Ni in proper amounts lowers the
viscosity of the alloy melt, thereby making a roll well wettable by
the alloy melt and thus improving the surface conditions of the
resultant Fe-based amorphous alloy ribbon. The alloy ribbon with a
smooth surface makes it possible to produce small, lightweight
magnetic cores with high space factors.
* * * * *