JPH0917623A - Nano crystal alloy magnetic core and its manufacture - Google Patents

Abstract

PURPOSE: To obtain a magnetic core having a small diameter which exhibits a high permeability, by performing heat treatment at a comparatively low temperature after heat treatment to raise the temperature higher than or equal to crystallization temperature. CONSTITUTION: A nano crystal alloy strip has composition containing the following as inevitable elements; at least one kind of element selected out of Cu and Au, at least one king of element selected out of Nb, Mo, Ta, Ti, Zr, Hf, V and W, at least one kind of element selected out of Si and B, and Fe. This mano crystal alloy magnetic core consists of the nano crystal alloy strip. The inner diameter is less than 10mm, and the permeability at 20kHz is at least 50000, or the rectangularity ratio is at most 30. This manufacturing method is as follows; after the temperature of a magnetic core composed of amorphous alloy of the same composition as the nano crystal alloy strip is raised higher than or equal to the crystallization temperature, and the core is maintained for at least 0 minutes and at most 24 hours for microcrystallization, heat treatment to maintain the core at a temperature of at least 60 deg.C and at most 300 deg.C for 5 minutes or longer. Thereby a nano crystal alloy magnetic core exhibiting remarkably high permeability and its manufacturing method can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nanocrystalline alloy magnetic core having a particularly high magnetic permeability, which is used for various magnetic parts such as various transformers and choke coils for noise filters, and a method for producing the same.

[0002]

2. Description of the Related Art Since nanocrystalline alloys have excellent soft magnetic properties, common mode choke coils, high frequency transformers,
It is used for magnetic cores such as earth leakage alarms and pulse transformers. As typical composition systems, the alloy systems described in Japanese Patent Publication No. 4393/1992 and JP-A-1-242755 are known. These nanocrystalline alloys are usually rapidly cooled from liquid phase or vapor phase to form amorphous alloys,
It is produced by microcrystallizing this by heat treatment. As a method of quenching from a liquid phase, a single roll method, a twin roll method, a centrifugal quenching method, a spinning method in a rotating liquid, an atomizing method, a cavitation method and the like are known. Further, as a method of rapidly cooling from a gas phase, a sputtering method, a vapor deposition method, an ion plating method, and the like are known. Nanocrystalline alloy is a microcrystal of amorphous alloy produced by these methods, and it has almost no thermal instability as seen in amorphous alloy, high saturation magnetic flux density, low magnetostriction and excellent softness. It is known to exhibit magnetic properties. Furthermore, it is known that the nanocrystalline alloy has a small change over time and is excellent in temperature characteristics.

By the way, as magnetic core materials used for noise filters, pulse transformers and the like, high magnetic permeability materials having excellent high frequency characteristics such as ferrite and amorphous alloy are used. Further, as described above, it is disclosed that the Fe-based microcrystalline alloy (nanocrystalline alloy) as described in JP-B-4-4393 exhibits high permeability and low core loss characteristics, and is suitable for these applications. ing.

In addition, ISDN (Integrated Service Digital Network [Integrated Ser
vices Digital Network]) The magnetic core material used for the interface pulse transformer is required to have high magnetic permeability and excellent temperature characteristics. In applications for ISDN, it is important that the magnetic permeability around 20kHz is high. Also,
Depending on the purpose of use, a flat BH rule with a low squareness ratio
What is needed is an index. However, in recent years, pulse transformers used for ISDN interfaces have been considered for use in card-type interfaces, and there is a growing demand for miniaturization and thinning, which requires an inductance of 20 mH or more at 20 kHz. In order to satisfy the standard with a small and thin shape, a material having higher magnetic permeability is required. In addition, interface cards typified by PC cards used in personal computers and the like tend to be thinned and downsized, and magnetic cores used for them are required to have a low height and a small diameter. It is like this.

However, ferrite and Fe-based amorphous alloys have low magnetic permeability, and it is difficult to meet the demand for such thinning and miniaturization. Further, ferrite has inferior temperature characteristics, and there is also a problem that the magnetic permeability sharply decreases especially at room temperature or lower. It is easy to obtain a Co-based amorphous alloy having a high magnetic permeability, but there is a problem in that when the ambient temperature is high, there is a problem that the change over time is large and the cost is high, and therefore there is a limit in using it for general-purpose parts. Further, in current sensors such as leakage alarms, magnetic sensors, etc., materials having higher magnetic permeability are required from the viewpoint of small size and high sensitivity. Further, from the viewpoint of realizing a linear output, a material having a low squareness ratio, a flat BH loop shape, an excellent constant magnetic permeability, and a high magnetic permeability is also required. On the other hand, the above-mentioned nanocrystalline alloy has a high magnetic permeability comparable to that of a Co-based amorphous alloy, and is considered to be promising for these applications.

[0006]

However, as a result of earnest studies by the present inventors, the magnetic core made of a small diameter nanocrystalline alloy produced by the conventional method has a lower magnetic permeability than the magnetic core having a large diameter. I found it easy. The degree of decrease in magnetic permeability due to this size reduction is larger than that of Co-based amorphous magnetic cores, etc. It has been found that it is difficult to achieve such a high magnetic permeability. An object of the present invention is to provide a small-diameter magnetic core having a high magnetic permeability and a method for producing a high-permeability nanocrystalline alloy magnetic core, which is highly effective for a small-diameter magnetic core.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inventors of the present invention selected from at least one element selected from Cu and Au, Nb, Mo, Ta, Ti, Zr, Hf, V and W. At least one element selected from the group consisting of Si, at least one element selected from the group consisting of B and a magnetic core consisting of a nanocrystalline alloy ribbon of a composition containing Fe as an essential element at a relatively low temperature The present invention was found by carrying out the heat treatment step, and found that even a magnetic core having an inner diameter of less than 10 mm could have a relative magnetic permeability at 20 kHz of 50,000 or more. That is, the present invention, Cu, at least one element selected from Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, Si, consisting of At least one element selected from the group and consisting of a nanocrystalline alloy ribbon of the composition containing Fe as an essential element, the inner diameter is less than 10 mm,
A nanocrystalline alloy magnetic core having a relative magnetic permeability at 20 kHz of 50,000 or more.

In particular, a nanocrystalline alloy magnetic core having a squareness ratio of 30% or less obtained by applying a magnetic field in a direction perpendicular to the magnetic path of the magnetic core and performing heat treatment in the magnetic field has a small change in relative permeability depending on the magnetized state, and is therefore demagnetized. Even if not sufficiently performed, the characteristics are stable, and more preferable results can be obtained. A particularly preferable squareness ratio is 20% or less. In the case of a wound magnetic core, the direction perpendicular to the magnetic path corresponds to the width direction of the ribbon used. By optimizing the heat treatment conditions, it is possible to achieve a very high magnetic permeability with a relative magnetic permeability of 70,000 or more at 20 kHz even with a core having an inner diameter of less than 10 mm.

According to another aspect of the present invention, at least one element selected from Cu and Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, Si. , A magnetic core made of an amorphous alloy having a composition containing at least one element selected from the group consisting of B and Fe as an essential element, a microcrystallized material that is heated to a crystallization temperature or higher and held for 0 minutes or more and 24 hours or less. The method for producing a nanocrystalline alloy magnetic core is characterized in that after the heat treatment step for performing the second heat treatment, a second heat treatment is carried out at a temperature of 60 ° C. or higher and lower than 300 ° C. for 5 minutes or longer. If the holding temperature of the second heat treatment is less than 60 ° C, the effect of sufficiently improving the magnetic permeability cannot be obtained, and if it is 300 ° C or higher, the magnetic permeability is rather lowered due to oxidation or induced magnetic anisotropy. A particularly desirable second heat treatment temperature range is 80 ° C to 200 ° C. The reason why the holding time of the second heat treatment is limited to 5 minutes or more is that the effect of the present invention is not remarkable when the holding time is less than 5 minutes.

As a specific heat treatment method, the temperature is raised from a temperature lower than the crystallization temperature to a temperature higher than the crystallization temperature, and 0 minutes or more 24
A method of performing a second heat treatment in which the temperature is maintained at a temperature of 60 ° C or higher and lower than 300 ° C for 5 minutes or more after the heat treatment step for microcrystallization in which the temperature is kept constant for a time or less and then cooled to room temperature Alternatively, the temperature is raised from the temperature lower than the crystallization temperature to the temperature above the crystallization temperature and maintained at a constant temperature for 0 minutes to 24 hours and then cooled to 60 ° C.
There is a method in which the temperature is kept above 300 ° C for 5 minutes or more and then cooled to room temperature. The effect of the present invention can be obtained even if the heat treatment for crystallization is performed in multiple stages or a plurality of times.

It is possible to change the shape of the BH loop by applying a magnetic field during at least part of the heat treatment process. In particular, when the direction in which the magnetic field is applied is perpendicular to the magnetic path of the magnetic core, it is possible to realize a magnetic core having a low squareness ratio and improved high frequency characteristics of permeability. In this case, the change in magnetic permeability is small and the characteristics can be stabilized even if the magnetic field is not completely demagnetized. In the case of a wound magnetic core, the direction perpendicular to the magnetic path corresponds to the width direction of the ribbon used.

[0012] according to the present invention the alloy has the general _{formula: (Fe 1-a M a} ) 100-xyzb A x M 'y M''z X b Si c B d ( atomic%) wherein M is Co, Ni At least one element selected from
At least one element selected from Cu, Au, M'is Ti, V, Zr,
Nb, Mo, Hf, at least one element selected from Ta and W, M '' is Cr, Mn, Sn, Zn, Ag, In, white metal element, Mg, Ca, Sr, Y,
Rare earth element, at least one element selected from N, O and S, X represents at least one element selected from C, Ge, Ga, Al and P, a, x, y, z, b , c and d are 0 ≦ a ≦ 0.
1, 0.1 ≦ x ≦ 3, 1 ≦ y ≦ 10, 0 ≦ z ≦ 10, 0 ≦ b ≦ 10, 11 ≦ c
An alloy having a composition represented by numbers satisfying ≦ 17 and 3 ≦ d ≦ 10 can be mentioned.

In the alloy according to the present invention, Cu, Au
The content x of at least one element selected from is 0.1 to 3
It is in the atomic% range. If it is less than 0.1 atom%, there is no effect of improving the magnetic permeability, whereas if it is more than 3 atom%, the saturation magnetic flux density and the magnetic permeability are lowered, which is not preferable. A more preferable range is 0.5 to 2 atomic%, and a particularly high magnetic permeability is obtained in this range.

M'is at least one element selected from the group consisting of Ti, V, Zr, Nb, Mo, Hf, Ta and W, and is Cu, Au.
And the like have the effect of making crystal grains finer and improving soft magnetic properties. The content y of M ′ is 1 to 10 atom%, and if it is less than 1 atom%, the effect of grain refinement is insufficient, and if it exceeds 10 atom%, the saturation magnetic flux density is remarkably reduced. The preferable content y of M'is 2 to 8 atom%. Ti, Zr, N
When b, Mo, Hf, Ta and W are not present, the crystal grains are not refined so much and the soft magnetic properties are poor. Nb, Mo, and Ta are particularly effective, but when Nb is added among these elements, the crystal grains tend to become finer and soft magnetic characteristics are excellent. The reason why the permeability increases due to the combined addition of Cu, Au and Ti, Zr, Nb, Mo, Hf, Ta and W is not clear, but it is considered as follows.

Since the interaction parameters of Cu, Au and Fe are positive and tend to separate, the alloy (film) in an amorphous state
When Fe is heated, Fe atoms or Cu, Au atoms gather together to form clusters, resulting in composition fluctuations.
For this reason, a large number of regions that are likely to be partially crystallized are formed, and a large number of fine crystal grains are formed with these regions as nuclei. This crystal grain contains Fe as a main component, and since there is almost no solid solubility of Fe, Cu, and Au, the Cu and Au concentrations around the crystal grain become high. In addition, there are many Si etc. around this crystal grain, and Ti, Zr, Nb, Mo,
When Hf, Ta, W, etc. are present, it is difficult to crystallize, and it is considered that crystal grains are difficult to grow. Therefore, it is considered that the crystal grains are made finer. As the crystal grains are made finer in this way, the magnetocrystalline anisotropy apparently cancels each other out, and the crystal phase is mainly Fe solid solution of bcc structure and the magnetostriction is small. It is considered that the soft magnetic properties are improved and the high magnetic permeability is obtained due to the reduced magnetic properties.

Cr, Mn, Sn, Zn, which are additional elements represented by M ",
Ag, In, white metal element, Mg, Ca, Sr, Y, rare earth element, N, O and S
At least one element selected from the group consisting of has the effect of improving corrosion resistance, improving magnetic properties, adjusting magnetostriction, etc., but its content is at most 10 atomic% or less. is there.

The alloy according to the present invention may contain 10 atomic% or less of at least one element selected from the group consisting of C, Ge, Ga, Al and P represented by X. These elements are effective for amorphization, and when added together with Si and B, they help amorphization of the alloy and are effective in adjusting magnetostriction and Curie temperature.

Si and B are elements particularly useful for refining the alloy. The Fe-based soft magnetic alloy film of the present invention is preferably obtained by once forming an amorphous alloy film by the effect of adding Si and B and then forming fine crystal grains by heat treatment. Si
The reason for limiting the contents c and d of B and B is that when the content c of Si is more than 17 atomic%, the saturation magnetic flux density is remarkably reduced and the soft magnetic characteristics are deteriorated. Further, the content d of B is 3
If it is less than atomic%, there is no effect of grain refinement, and it is 10 atomic%.
This is because if the amount is larger, the saturation magnetic flux density decreases and the soft magnetic characteristics deteriorate.

The balance is essentially Fe mainly except impurities, but a part of Fe may be replaced by the component M (Co and / or Ni). The content a of M is 0 ≦ a ≦ 0.1. a
This is because if the value exceeds 0.1, the magnetic permeability may decrease. Co substitution also has the effect of increasing the saturation magnetic flux density, and a smooth choke coil used for high coercive force recording media,
It is more advantageous as a low frequency transformer material.

The alloy ribbon according to the present invention is usually manufactured as follows. First, an amorphous alloy ribbon having a plate thickness of about 3 to 100 μm is formed in the atmosphere, an inert gas atmosphere such as argon or helium, or a decompressed atmosphere such as helium by a liquid quenching method such as a single roll method or a twin roll method. Made in. If necessary, the ribbon is slit. The thickness of the ribbon is 20
It is more preferable that the thickness be less than or equal to μm, and particularly preferable that the thickness be less than or equal to 15 μm, and a higher magnetic permeability can be realized with a small diameter magnetic core.
Next, the alloy ribbon is wound into a toroidal shape, and then heat-treated in an atmosphere of an inert gas such as argon gas or nitrogen gas or in a vacuum to produce a magnetic core made of the alloy ribbon made of the fine crystal grains. .

At this time, if the surface of the alloy ribbon is covered with an oxide such as SiO ₂ or Al ₂ O ₃ to perform interlayer insulation, more preferable results can be obtained especially in a wide material. As the method of interlayer insulation, a method of depositing an oxide such as MgO by an electrophoretic method, or applying a metal alkoxide solution on the surface and subjecting it to heat treatment
SiO ₂ , Li ₂ O, a method of forming a film of oxide such as MgO, a method of performing phosphate or chromate treatment to coat the surface with an oxide, and flowing fine ceramic powder into There is a method of passing the ribbon and attaching it. A tension of 50 MPa or less at the time of manufacturing the wound magnetic core is usually desirable for achieving high magnetic permeability. As a result, the effect of improving the characteristics of the manufacturing method of the present invention becomes more remarkable. Further, the magnetic core is used by putting it in a core case or coating the periphery thereof as needed. It may be impregnated with an epoxy resin, a polyimide resin, an acrylic resin, or a silicon resin.

[0022]

[Operation] In the case of a small-diameter magnetic core, a force is applied between the ribbons, and the magnetic characteristics are likely to deteriorate. Even if the tension is adjusted when manufacturing a wound magnetic core, the effect is completely eliminated in the case of a small-diameter magnetic core. It is difficult. The present invention reduces the effect of stress acting on the ribbon in a small-diameter magnetic core by performing a heat treatment of 60 ° C to 300 ° C after the heat treatment of raising the temperature above the crystallization temperature, resulting in a very high magnetic permeability. There is an effect that it can be realized.

[0023]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. (Example 1) Cu 1%, Nb 3.1%, Si 15.6%, B 6.6 in atomic%
The remaining alloy melt consisting essentially of Fe was quenched by the single roll method to obtain an amorphous alloy ribbon with a width of 25 mm and a thickness of 18 μm. Next, this thin strip was slit into a width of 3 mm. This slit-processed amorphous alloy ribbon was wound around an outer diameter of 7.5 mm and an inner diameter of 4.5 mm to produce a toroidal magnetic core. The crystallization temperature T _x of this alloy was measured and found to be 508 ° C. The prepared magnetic core was inserted into a heat treatment furnace kept at 450 ° C. in an argon atmosphere, and heat-treated in a heat treatment pattern shown in FIGS. 1 (a) and 1 (b) to produce a nanocrystalline alloy magnetic core. For comparison, the conventional heat treatment pattern shown in (c) was also used. H = 360K in the direction perpendicular to the magnetic path during heat treatment above the crystallization temperature
A magnetic field of A · m ⁻¹ was applied. Table 1 shows the obtained magnetic characteristics.

[0024]

[Table 1]

As can be seen from the table, the magnetic core subjected to the heat treatment of the present invention has characteristics that the specific initial permeability μ _{20k at} 20 kHz is 50,000 or more. On the other hand, the conventional heat treatment method can obtain only a value of μ _20k of less than 50,000 with such a small-diameter magnetic core.

(Example 2) Cu 1%, Nb 3%, Si 1 in atomic%
4.8%, B 7.5% balance The alloy melt consisting essentially of Fe is rapidly cooled by the single roll method in helium gas under a reduced pressure, and the width is 1.
An amorphous alloy ribbon having a thickness of 3 mm and a thickness of 8 μm was produced. Next, the surface of this amorphous alloy ribbon was covered with SiO ₂ . This amorphous alloy ribbon was wound around an outer diameter of 8 mm and an inner diameter of 4 mm to produce a toroidal magnetic core. The crystallization temperature T _x of this alloy was measured and found to be 520 ° C. Next, this alloy was heat-treated by the heat treatment pattern shown in FIG. 2 to measure the magnetic characteristics. During the heat treatment at the crystallization temperature or higher, a magnetic field of H = 360 KA · m ⁻¹ was applied in the direction perpendicular to the magnetic path. Table 2 shows the obtained results. 5 when the second heat treatment temperature is 60 ℃ -300 ℃
It can be seen that μ _{20k of} 0000 or more is obtained.

[0027]

[Table 2]

Example 3 A molten alloy having the composition shown in Table 3 was rapidly cooled by a single roll method to obtain an amorphous alloy ribbon having a width of 50 mm and a thickness of 15 μm. Next, after slitting this ribbon to a width of 2 mm, this alloy ribbon was wound around an outer diameter of 9 mm and an inner diameter of 5 mm to produce a toroidal magnetic core. Next, heat treatment was performed using the heat treatment pattern shown in FIG. For comparison, a sample heat-treated by a conventional heat-treatment pattern without the second heat treatment was also prepared. During heat treatment above the crystallization temperature, H = 36 in the direction perpendicular to the magnetic path.
A magnetic field of ⁰ KA · m ⁻¹ was applied. The results of measuring the magnetic properties are shown in Table 3.

[0029]

[Table 3]

The magnetic core of the present invention has a small diameter but a high magnetic permeability. On the other hand, in the conventional heat treatment pattern, the magnetic permeability of the small diameter magnetic core is lower than that of the magnetic core of the present invention.

(Example 4) Cu 1%, Nb 2.5%, Cr in atomic%
0.2%, Si 15.8%, B 7.2%, Sn 0.07% Remaining alloy melt consisting essentially of Fe was quenched by the single roll method, and width 1.5 mm thickness 1
A 2 μm amorphous alloy ribbon was obtained. The crystallization temperature of this alloy was 495 ° C. The amorphous alloy ribbon was wound by changing the inner diameter and the outer diameter, to produce a toroidal magnetic core having the shape shown in Table 4. Next, heat treatment was performed using the heat treatment pattern shown in FIG. Table 4 shows the relative magnetic permeability at 20 kHz. For comparison, the characteristics when the conventional heat treatment shown in FIG. 4B is also shown. During the heat treatment at the crystallization temperature or higher, a magnetic field of H = 360 KA · m ⁻¹ was applied in the direction perpendicular to the magnetic path.

[0032]

[Table 4]

When the heat treatment of the present invention is performed, even if the inner diameter is 10 mm or less, a high μ _{20k of} 50,000 or more can be realized.
When the conventional heat treatment is performed, the decrease in magnetic permeability is large especially when the inner diameter is 10 mm or less. As described above, by applying the heat treatment method of the present invention, high magnetic permeability can be realized even with a small-diameter magnetic core.

[0034]

According to the present invention, it is possible to provide a nanocrystalline alloy magnetic core exhibiting a remarkably high magnetic permeability and a method for producing the same, and the effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a heat treatment pattern according to the present invention and a conventional heat treatment pattern.

FIG. 2 is a view showing a heat treatment pattern according to the present invention.

FIG. 3 is a view showing a heat treatment pattern according to the present invention.

FIG. 4 is a diagram showing a heat treatment pattern according to the present invention and a conventional heat treatment pattern.

Claims (10)

[Claims] 1. A group consisting of at least one element selected from Cu and Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, and Si and B. Consisting of a nanocrystalline alloy ribbon having a composition containing at least one element selected from Fe and Fe as an essential element, an inner diameter of less than 10 mm, and a relative magnetic permeability at 20 kHz of 50,000 or more. . 2. The nanocrystalline alloy magnetic core according to claim 1, wherein the squareness ratio is 30% or less. 3. The nanocrystalline alloy magnetic core according to claim 1, wherein the relative magnetic permeability at 20 kHz is 70,000 or more. Wherein the general _{formula: (Fe 1-a M a} ) 100-xyzb A x M 'y M''
_z X _b Si _c B _d (atomic%) In the formula, M is at least one element selected from Co and Ni, and A is
At least one element selected from Cu, Au, M'is Ti, V, Zr,
Nb, Mo, Hf, at least one element selected from Ta and W, M '' is Cr, Mn, Sn, Zn, Ag, In, white metal element, Mg, Ca, Sr, Y,
Rare earth element, at least one element selected from N, O and S, X represents at least one element selected from C, Ge, Ga, Al and P, a, x, y, z, b , c and d are 0 ≦ a ≦ 0.
1, 0.1 ≦ x ≦ 3, 1 ≦ y ≦ 10, 0 ≦ z ≦ 10, 0 ≦ b ≦ 10, 11 ≦ c
The nanocrystalline alloy magnetic core according to any one of claims 1 to 3, comprising a nanocrystalline alloy ribbon having a composition represented by a number satisfying ≤17 and 3≤d≤10. 5. A group consisting of at least one element selected from Cu and Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, and Si and B. A magnetic core made of an amorphous alloy having a composition containing at least one element selected from Fe and Fe as an essential element, a heat treatment step for microcrystallization for raising the temperature to a crystallization temperature or higher and holding it for 0 minute to 24 hours. A method for producing a nanocrystalline alloy magnetic core, which is characterized in that after that, a second heat treatment is carried out at a temperature of 60 ° C. or higher and lower than 300 ° C. for 5 minutes or longer. 6. A group consisting of at least one element selected from Cu and Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, and Si and B. The core made of an amorphous alloy with a composition containing at least one element selected from Fe and Fe as an essential element is heated from a temperature lower than the crystallization temperature to the crystallization temperature or higher and maintained at a constant temperature for 0 minutes or more and 24 hours or less. After the heat treatment step for microcrystallization for further cooling to room temperature, a second heat treatment is performed in which the temperature is raised from room temperature to a temperature of 60 ° C or higher and lower than 300 ° C and held for 5 minutes or longer. 5. The method for producing the nanocrystalline alloy magnetic core according to 5. 7. A group consisting of at least one element selected from Cu and Au, at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V and W, and Si and B. A magnetic core made of an amorphous alloy having a composition containing at least one element selected from Fe and Fe as an essential element, and the temperature is raised from a temperature lower than the crystallization temperature to the crystallization temperature or more to a constant temperature of 0 minutes or more and 24 hours or less. The method for producing a nanocrystalline alloy magnetic core according to claim 5, characterized in that the nanocrystalline alloy magnetic core is cooled after being held, and after being held at a temperature of 60 ° C or higher and lower than 300 ° C for 5 minutes or more, then cooled to room temperature. 8. The method for producing a nanocrystalline alloy magnetic core according to claim 5, wherein a magnetic field is applied during at least a part of the heat treatment step. 9. The method for producing a nanocrystalline alloy magnetic core according to claim 8, wherein the direction in which the magnetic field is applied is perpendicular to the magnetic path of the magnetic core. 10. A general formula: (Fe _1-a M _a ) _100-xyzb A _x M '
_y M '' _z X _b Si _c B _d (atomic%) In the formula, M is at least one element selected from Co and Ni, and A is
At least one element selected from Cu, Au, M'is Ti, V, Zr,
Nb, Mo, Hf, at least one element selected from Ta and W, M '' is Cr, Mn, Sn, Zn, Ag, In, white metal element, Mg, Ca, Sr, Y,
Rare earth element, at least one element selected from N, O and S, X represents at least one element selected from C, Ge, Ga, Al and P, a, x, y, z, b , c and d are 0 ≦ a ≦ 0.
1, 0.1 ≦ x ≦ 3, 1 ≦ y ≦ 10, 0 ≦ z ≦ 10, 0 ≦ b ≦ 10, 11 ≦ c
The method for producing a nanocrystalline alloy magnetic core according to any one of claims 5 to 9, comprising an amorphous alloy having a composition represented by a number satisfying ≤17 and 3≤d≤10.