JP2002343618A - Soft magnetic material and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-resistance soft magnetic material having superior manufacture reproductivity. SOLUTION: This soft magnetic material contains magnetic particles 2, which are formed of metal particles 21, that are made of iron alloy containing at least one of silicon and aluminum and of which the average particle size is 10-400 μm, and an insulation oxide film 22 of 0.2-10 μm in thickness, that is made mainly of either of silicon and aluminum that tends to be oxidized as compared with iron covering the periphery of the metal particles, and a binder metal to joint the magnetic particles with each other, and it is made a molded body having a volume of metal particles at 80% of the whole body, and the binder metal is a copper alloy containing at least one among copper oxide, phosphorus, aluminum, zinc, and silicon that are easier to be oxidized than iron, and set at 1-5 wt.%. In addition, if thickness is defined as t and the width as w, the metal particle is of plate shape, having an aspect ratio (w/t) of 10 to 100 and width (w) of 10-4,000 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material applied to electric equipment such as a motor, a reactor, a transformer, a yoke for a magnetic head, and more particularly to a material having a low eddy current loss, a high saturation magnetic flux density and a high magnetic permeability at a high frequency. The present invention relates to a soft magnetic material and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, electric devices such as motors have been frequently used in a high frequency range. As a magnetic material used for such a device, a soft magnetic material having excellent magnetic properties is selected and used. However, in AC use, iron loss (sum of hysteresis loss and eddy current loss) is large, resulting in energy loss. Eddy current loss increases in proportion to the square of the frequency, so in order to reduce AC loss,
For example, a silicon steel sheet is laminated and used. Nevertheless, eddy current loss accounts for 20% of iron loss in the commercial frequency range. Also, 1 kHz
If it exceeds z, the eddy current loss becomes larger than the hysteresis loss and the hysteresis loss also becomes larger. Therefore,
A magnetic material used in a high frequency region can be used only at a magnetic flux density much lower than the original material itself's saturation magnetic flux density due to a decrease in magnetic permeability. Energy conservation is also being called out from global environmental issues, and it is essential to improve the efficiency of motors. In order to solve such problems, application of amorphous to soft magnetic material was studied. However, although there is an effect of reducing eddy current loss, magnetic properties are reduced by a small stress at the time of product molding. Limited. Further, as seen in Japanese Patent Publication No. 6-82577, a dust core made by compression molding iron covered with an oxide film, or a resin disclosed in JP-A-9-102409 was coated on the surface of the iron powder. Resin moldings were considered. Powder magnetic cores have weak binders, so their use is limited because the molded product is chipped or cracked during handling, and high temperature that improves magnetic properties within a range where electrical resistance does not decrease Since the heat treatment could not be performed for a long time, the magnetic properties were also insufficient. Since the resin molded body uses resin as a binder, heat treatment to improve the magnetic properties of iron deteriorated by stress at the time of molding cannot be performed at 700 ° C or more, so only electric resistance is large, but magnetic Properties were very low. If the heat treatment is performed at 700 ° C or higher, the resin film disappears and the electric resistance decreases. In order to solve the above problems, there has been proposed a material and a manufacturing method (JP-A-11-23861).
Four ). FIG. 5 is a schematic diagram of a cross section of a soft magnetic material formed by this method. In the figure, 1 is a compact, 2 is magnetic particles, and 3 is a binding metal. The molded body 1 is composed of magnetic particles 2 and a bonding metal 3 for bonding them. Magnetic particles 2
Are metal particles 2 made of an iron alloy having an average particle size of 10 to 400 μm.
1 and an oxide film of a metal which is more easily oxidized than iron covering the periphery thereof, that is, an insulating oxide film 22 (alumina or the like). Bonding metal 3 is the same metal as the element constituting insulating oxide film 22 or an alloy thereof, and is aluminum here. FIG. 6 shows an example of a manufacturing process of the molded body 1. That is, it is as follows. (1) The surfaces of the metal particles 21 (iron alloy particles) are oxidized. (2) The metal particles 21 whose surfaces are oxidized are put into a mold and molded. (3) Impregnating aluminum as the bonding metal 3. While the compact is being heated, the voids of the compact are impregnated with molten aluminum, which is more easily oxidized than iron. (4) Heat the molded body. Iron oxide generated on the surface of the metal particles 21 is changed to alumina by a contact reaction with molten aluminum. Thus, a molded body of the soft magnetic material is completed. This insulating oxide film 22 (alumina)
Since it is thin and has excellent electrical insulation properties, its characteristics do not deteriorate even when it is heated to 700 ° C. or more, so it is an excellent material as a high-resistance soft magnetic material. The bonding metal 3 may be magnesium in addition to aluminum. It is characterized by taking electrical insulation with the formed alumina or magnesia.

[0003]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 11-238614, since the contact reaction between the iron oxide and the molten aluminum or the molten magnesium occurs extremely rapidly, it is difficult to control the reaction. The reaction between iron oxide and molten aluminum is also known as thermite reaction and is known to react explosively. Since the control of the reaction is difficult, reproducibility during production is difficult depending on the state of filling of the molten metal, and there is a problem that a material having excellent characteristics cannot be stably obtained. In addition, since iron alloy particles have a large demagnetizing field due to the particle shape and a low initial magnetic permeability, when such a material is used for an apparatus, it is not enough to achieve miniaturization. Accordingly, an object of the present invention is to provide a high-resistance soft magnetic material having excellent production reproducibility and high initial magnetic permeability, and a method for producing the same.

[0004]

According to a first aspect of the present invention, there is provided a soft magnetic material comprising an iron alloy containing at least one element of silicon and aluminum and having an average particle size of 10 to 400 μm. A magnetic particle composed of metal particles and an insulating oxide film having a thickness of 0.2 to 10 μm and containing silicon or aluminum as a main component, which is more easily oxidized than iron covering the periphery of the metal particles; A metal having a volume of 80% or more of the total volume of the metal particles, wherein the binding metal is at least one of copper oxide, phosphorus, aluminum, zinc, and silicon, which is more easily oxidized than iron. One is a copper alloy containing 1 to 5 wt%. The soft magnetic material according to claim 2, wherein the metal particles
When the thickness is t and the width is w, the aspect ratio (w / t) is 10
-100, and a width (w) of 10-4000 μm. According to the soft magnetic material according to claims 1 and 2,
Since the electric insulating film is not broken even by high-temperature annealing, eddy current hardly occurs, and a high permeability material can be obtained because the distortion of the iron alloy particles is small. The method for producing a soft magnetic material according to claim 3, wherein at least one of silicon and aluminum is used.
Made of an iron alloy containing two elements with an average particle size of 10 to 400 μm
Magnetic particles comprising metal particles and an iron oxide film containing iron as a main component covering the periphery of the metal particles to form a molded body,
A molten copper alloy, which is a bonding metal that bonds the magnetic particles together while the molded body is being heated, is impregnated into the voids of the molded body, and subsequently heat-treated, and the iron is formed by silicon and aluminum in the metal particles. Reduces the oxygen in the oxide film,
This is changed to an insulating oxide film containing silicon or aluminum as a main component. A method for producing a soft magnetic material according to claim 4 is characterized in that a metal particle made of an iron alloy containing at least one element of silicon and aluminum and having an average particle diameter of 10 to 400 μm is formed into a compact, and the compact is formed. A bonding metal that oxidizes the surface of the metal particles by heating to 300 ° C. or higher to form an iron oxide film containing iron as a main component, and then bonds the magnetic particles together while the molded body is heated. The molten copper alloy is impregnated into the voids of the compact, and subsequently heat-treated to reduce oxygen in the iron oxide film by at least one of silicon and aluminum in the metal particles,
This is changed to an insulating oxide film containing silicon or aluminum as a main component. The method for producing a soft magnetic material according to claim 5, wherein the main component is a metal particle made of an iron alloy containing at least one element of silicon and aluminum and having an average particle diameter of 10 to 400 µm and iron surrounding the metal particle. Magnetic particles comprising an iron oxide film to be formed, and particles of a copper alloy which is a binding metal that binds the magnetic particles together to form a molded body, and heat-treats the molded body to form a metal body. The oxygen in the iron oxide film is reduced by at least one of silicon and aluminum to convert it into an insulating oxide film containing silicon or aluminum as a main component. The method for producing a soft magnetic material according to claim 6, wherein the copper alloy is more easily oxidized than iron, such as copper oxide, phosphorus, aluminum, zinc,
At least one of silicon and magnesium is contained in an amount of 1 to 5% by weight. The method for producing a soft magnetic material according to claim 7, wherein the metal particles made of the iron alloy have an aspect ratio (w / t) of 10 to 100 and a width (w) when the thickness is t and the width is w. In a plate shape of 10 to 4000 μm. According to the method for manufacturing a soft magnetic material according to claims 3 to 7, a soft magnetic material having excellent manufacturing stability and high reproducibility can be obtained because the insulating oxide film can be gradually formed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a material and a method for producing the same were studied on how to stably control the reaction rate during production. As a result, the reaction rate is controlled not by using a fast-reacting binding metal such as aluminum, but by adding a metal element, aluminum or silicon, which is more easily oxidized than iron, to metal particles of an iron alloy in advance. The present inventors have found a method of gradually diffusing the surface of iron particles by heat treatment to react with iron oxide to change into an insulating oxide film such as aluminum and silicon. In addition, a copper alloy to which an element having good adhesion and reacting with iron oxide is added as a binding metal is used. The specific features of the present invention are as follows. (1) Bonding metal When a molten copper alloy is pressed into a molded body of iron-aluminum alloy particles whose surface has been oxidized and heated and held, oxygen of iron oxide is reduced and changed to aluminum-based oxide. That is, a magnetic material in which a copper alloy as a binding metal exists between magnetic particles of an iron alloy mainly covered with alumina and magnetic particles is produced. Since the boundary between the copper alloy as the bonding metal and alumina also partially reacts, the bonding force is increased.
The alloy component added to copper is preferably an element having good wettability with iron oxide. Copper oxide, phosphorus, aluminum,
Examples include zinc, silicon, and magnesium. But,
If the content is less than 1%, it is difficult to react, and if it exceeds 5%, the reaction is too fast and the production stability is lost. (2) Thickness of Insulating Oxide Film The thickness of the insulating oxide film is limited by the specific resistance value and the saturation magnetic flux density. If the insulating oxide film is too thin, insulating properties cannot be maintained. The specific resistance of the oxide film is desirably 100 μΩcm or more. The specific resistance value of 100 μΩcm is five times the value of a silicon steel plate (20 μΩcm), whereby the loss can be reduced to one fifth. If the insulating oxide film is too thick, the presence of a non-magnetic phase in the material as a whole increases, leading to a decrease in the saturation magnetic flux density. When the thickness of the magnetic particles is 10 μm and the film thickness is 0.2 μm or less, and when the particle size is 400 μm and the film thickness is 10 μm or less, the saturation magnetic flux density becomes poor at 15,000 G or less. (3) Average particle size, material, and manufacturing method of magnetic particles If the average particle size of the magnetic particles is less than 10 μm, the magnetic permeability decreases. On the other hand, if it is larger than 400 μm, the loss increases due to eddy current generated in the particles. Since iron oxide has insufficient electrical insulation, a metal element that is more easily oxidized than iron and an insulating oxide film that has excellent electrical insulation is preferably a metal element that has a higher oxide generation energy than iron. Examples include aluminum and silicon. Therefore, the alloy components for forming the oxide of the iron alloy as the metal particles are aluminum and silicon. On the other hand, the reason why the volume of the iron alloy particles is set to 80% or more is that the saturation magnetic flux density becomes less than 15,000 G when the portion of the magnetic material decreases. Currently used magnetic steels, Fe-Si, Fe-Al, Sendust, Fe-25Co, Fe-5
Alloys such as 0Co are 15,000G. Fe-25Co, Fe-50Co
Was made of iron alloy metal particles, an alloy component for forming an insulating oxide film was further added to these alloys. Various methods can be applied to the method for producing metal particles. Among the plasma methods, the water plasma method is advantageous in terms of cost. The reason is that the surface is oxidized simultaneously with the production of the particles, so that the step of the oxidation treatment can be omitted. (4) Impregnation of Bonding Metal and Heat Treatment When impregnating the binding metal, it is easier to press the melted metal in between the particles, and it is more preferable to reduce the pressure. Also, when compacting powders to produce a compact,
Sintering is desirable for increasing the strength. The purpose of the heat treatment is twofold. One is to form a new insulating oxide film simultaneously with the reduction of the iron oxide film. For example, when aluminum in an iron-aluminum alloy is brought into contact with iron oxide at 300 ° C. or more, iron oxide is reduced to aluminum oxide. The other is a reaction between an alloy component in a copper alloy as a bonding metal and iron oxide. 300 ° C for all reactions
A lower temperature of less than 10 mm is acceptable, but it takes time and is disadvantageous in cost. An insulating oxide film is more likely to be formed in a vacuum atmosphere. Iron oxides are Fe2O3, Fe3O4, FeO, and their composite substances.To reduce these iron oxides, iron oxides may remain depending on the reduction conditions,
There is no problem as long as there is no influence on the characteristics. (5) Aspect ratio As a result of studying the improvement of the initial magnetic permeability, the demagnetizing field can be reduced by selecting the shape of the magnetic particles (iron alloy), that is, by increasing the ratio of the width to the thickness of the particles. Was found to improve. The iron alloy particles of the present invention,
It is manufactured by an atomizing method, a carbonyl method, an electrolytic method, a quenching method, a punching method, or the like. FIG. 4 shows a method for producing iron alloy particles by the centrifugal atomization method. The particle shape of the molten iron alloy can be changed by adjusting the viscosity of the molten iron alloy, the atmospheric gas, and the amount of iron or iron alloy to be supplied, depending on the added element. Plate-like metal particles (iron alloy) are produced according to the particle shape of the molten metal. The desired shape can also be obtained by crushing the granular particles by rolling.
The simplest method is to obtain a target shape by punching a plate obtained by a quenching method or the like. The length and thickness of the plate-like iron alloy particles to be produced are limited by the generated initial permeability, eddy current loss, and saturation magnetization. When the aspect ratio (w / t) of the plate-like particles is smaller than 10, the initial magnetic permeability decreases. On the other hand, if the width is larger than 4000 μm, the loss increases due to the eddy current generated in the particles. Even if the width is less than 10 μm, the magnetic permeability decreases.

[0006]

(First Embodiment) FIG. 1 is a schematic view showing a cross section of a soft magnetic material according to a first embodiment of the present invention. The appearance is the same as that of the conventional example, and the molded body 1 is composed of the magnetic particles 2 and the bonding metal 3 for bonding these particles.
Means metal particles 21 (iron alloy) having an average particle size of 10 to 400 μm
And an oxide film of a metal that is more easily oxidized than iron that surrounds it,
That is, the insulating oxide film 22 is formed. The metal particles 21
Fe-3% Si, Fe-7% Si, Fe-5% Al, Fe-25Co-3Al, Fe-50Co-5S
i, Fe-5Si-1Al was used. The insulating oxide film 22 is made of SiO2
And Al2 O3, the film thickness was approximately 1 .mu.m. The bonding metal 3 is Cu-3.5P, Cu-1.5Cu2O, Cu-5Al, Cu-3Si, Cu-3P
And Cu-3Zn copper alloy. The mixing of the metal particles 21 and the binding metal 3 was performed by adjusting the amount of the metal particles 21 and the amount of the binding metal 3 so that the volume of the metal particles 21 was 80% or more. The oxidation treatment of the metal particles 21 is performed at 350 ° C. in air.
For 8 hours. The molded body 1 is formed into a rectangular parallelepiped having a length of 5 mm, a width of 10 mm and a length of 60 mm by using the three methods shown in FIG.
Press molding was performed at ton / cm2. For the impregnation of the bonding metal 3, after the heating, the molten metal was press-fitted by a press-fitting device (not shown). The heat treatment after the impregnation was performed at two temperatures: a melting temperature during the impregnation and a temperature lower than the melting temperature. Table 1 shows sample types and manufacturing conditions.

[0007]

[Table 1]

The method shown in FIG. 2 (a) is a process in which the metal particles 21 (iron alloy) are oxidized, and then subjected to molding, impregnation with a bonding metal, and heat treatment. 7, 8
It is. FIG. 2 (b) shows the process of surface oxidation, bonding metal impregnation, and heat treatment after molding.
~ 6. FIG. 2 (c) shows that Fe
The magnetic particles 2 on which the 2O3 film is formed and the copper alloy particles of the bonding metal 3 are mixed, formed by pressing, and then subjected to a heat treatment to change into the insulating oxide film 22. The heat treatment was performed in a vacuum at a temperature of 750 ° C. (sample No. 9). In addition,
As a comparative example, magnetic particles 2 were made of Fe-5Al, oxidized after forming, and impregnated with Al as the bonding metal 3. The thickness and material of the insulating film of the formed body were measured with an electron microscope and an X-ray microanalyzer. Iron oxide remained in some of the insulating films. Next, the specific resistance value and the saturation magnetic flux density of the manufactured sample were measured to evaluate the characteristics. The measurement results and evaluation of the resistance value are also shown in the right end column of Table 1. The samples of the present invention (Nos. 1 to 9) showed extremely stable characteristics with a variation in resistance of ± 70 or less. In contrast, the conventional sample used as a comparative example
The characteristic variation was as large as ± 200 and extremely unstable. In addition, according to the results of measuring the saturation magnetic flux density with a BH tracer, all the samples of the present invention exceeded 15,000 Gauss,
Good characteristics were obtained. In contrast, 15,000 in the comparative example
The value was as low as 0 Gauss or less. Further, the molded article was bent to examine the adhesion between the insulating oxide film and the bonding metal. As a result, it was found that the sample of the present invention was extremely superior to the comparative example. As described above, since stable characteristics are obtained, electric devices with small loss can be mass-produced.

(Second Embodiment) FIG. 3 shows a schematic diagram of a cross section of a soft magnetic material according to a second embodiment of the present invention. In the present embodiment, plate-shaped metal particles (iron alloy particles) 21 are used to improve the initial magnetic permeability. The iron alloy particles have an aspect ratio (width w / thickness t) of 10 to 100 and a width w
Is 10 to 4000 μm. An insulating oxide film 22 is formed on the surface of the iron alloy particles in the same manner as in the first embodiment, and is bonded by the copper alloy of the bonding metal 3. Iron alloy particles, Fe-3Si, Fe-7Si, Fe-5Al, using a plate thickness t of 0.5 to
The width was 100 μm, and the width w was 10 to 4500 μm. The insulating oxide film 22 was made of SiO2 and Al2 O3 and had a thickness of about 1 .mu.m. The bonding metal 3 is Cu-3.5
A copper alloy of P, Cu-1.5Cu2O, Cu-3Al, Cu-3Mg and Cu-Al-11Si was used. The manufacturing method was the same as in the first embodiment, using the three methods shown in FIG. As comparative examples, iron alloy particles having a small aspect ratio and particles having a large width were also added. Table 2 shows the samples used in the present invention.

[0010]

[Table 2]

The plate-like metal particles (iron alloy particles) 21 were produced by a centrifugal atomizer shown in FIG. Crucible 4
The iron alloy 5 is put into the furnace and heated to about 1500 ° C. by the heater 6 to melt the iron alloy 5. The molten iron alloy 5 is ejected from the nozzle 7 and collides with the rotated disk 8. The aspect ratio of the iron alloy particles was determined by adjusting the rotation speed of the disk 8 and the viscosity of the molten iron alloy. Although the viscosity of the molten metal changes depending on the temperature, composition, and oxygen concentration of the atmosphere of the molten metal, in this embodiment, the acidity concentration in the container 9 was adjusted by argon and nitrogen to adjust the atmosphere. The manufacturing steps of the soft magnetic material are the three types shown in FIG. 2 as in the first embodiment. The method of FIG. 2A is for sample No. 1 in Table 2, and FIG. 2B is for sample Nos. 2 to 12. The method of FIG. The thickness of the insulating oxide film was measured with an electron microscope and an X-ray microanalyzer. Next, the result of measuring the initial magnetic permeability of the manufactured sample is also shown in the right end column of Table 2. Samples 1 to 13 used as examples of the present invention have an initial magnetic permeability of 500
The above shows good characteristics. The saturation magnetic flux density
As good as 15,000G or more. On the other hand, among the samples used as comparative examples, those having a small aspect ratio have a small initial permeability of 500 or less and a large aspect ratio.
Those having a large width had an initial magnetic permeability of 500 or more, but were difficult to produce powder.

[0012]

As described above, according to the present invention, the iron alloy particles 1 having an average particle diameter of 10 to 400 .mu.m covered with an insulating oxide film 2 having a thickness of 0.2 to 10 .mu.m which is more easily oxidized than iron. The metal element forming the insulating oxide film is made of at least one of the alloying elements forming the iron alloy, and the particles covered with the insulating oxide film are combined with an alloy mainly containing copper. In this case, the iron alloy occupies 80% by volume or more of the molded body, so that there is an effect of obtaining a soft magnetic material with less variation in resistance value and saturation magnetic flux density characteristics.
Further, since the iron alloy particles are formed in a plate shape and the aspect ratio is specified, a soft magnetic material having a high initial magnetic permeability can be obtained, and an electric device with a small loss can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cross section of a soft magnetic material molded body according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a manufacturing process of a soft magnetic material of the present invention.

FIG. 3 is a schematic view showing a cross section of a soft magnetic material molded body according to a second embodiment of the present invention.

FIG. 4 is a schematic view showing an apparatus for producing iron alloy particles used in a second embodiment of the present invention.

FIG. 5 is a schematic view showing a cross section of a conventional soft magnetic material molded body.

FIG. 6 is a block diagram showing a manufacturing process of a conventional soft magnetic material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded body 2 Magnetic particle 21 Metal particle (iron alloy particle) 22 Insulating oxide film 3 Bonding metal 4 Crucible 5 Iron alloy 6 Heater 7 Nozzle 8 Disk 9 Container

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/00 303 C22C 38/16 38/16 H01F 1/14 A (72) Inventor Mitsuaki Ikeda Kitakyushu, Fukuoka Prefecture 2-1 Kurosaki Castle Stone, Yawata Nishi-ku Yasukawa Electric Co., Ltd. F-term (reference) 4K018 AA10 AA25 AA26 AA29 BA15 BA16 BB01 BB04 BC18 CA11 FA08 FA36 KA43 KA44 5E041 AA04 CA02 CA04 CA05 NN01

Claims (7)

[Claims] (1) A metal particle comprising an iron alloy containing at least one element of silicon and aluminum and having an average particle diameter of 10 to 400 μm, and any one of silicon and aluminum which are more easily oxidized than iron covering the periphery of the metal particle. Thickness of the main component 0.2 ~
A soft magnetic material comprising a magnetic body comprising a 10 μm insulating oxide film and a binding metal for binding the magnetic particles together, and wherein the volume of the metal particle is 80% or more of the whole, A soft magnetic material characterized in that the binding metal is a copper alloy containing 1 to 5% by weight of at least one of copper oxide, phosphorus, aluminum, zinc and silicon, which is more easily oxidized than iron. 2. The metal particles are in the form of a plate having an aspect ratio (w / t) of 10 to 100 and a width (w) of 10 to 4000 μm, where t is the thickness and w is the width. The soft magnetic material according to claim 1, wherein 3. The method according to claim 1, wherein metal particles made of an iron alloy containing at least one element of silicon and aluminum and having an average particle size of 10 to 400 μm are heated to 300 ° C. or more to oxidize the surface of the metal particles and to mainly contain iron. Forming an iron oxide film as a component to form magnetic particles, and then forming the magnetic particles into a molded body, and a molten copper alloy that is a bonding metal that binds the magnetic particles together while the molded body is heated. Is impregnated into the voids of the compact, and subsequently heat-treated, silicon in the metal particles,
A method for manufacturing a soft magnetic material, comprising reducing oxygen in the iron oxide film with aluminum to convert it to an insulating oxide film containing silicon or aluminum as a main component. 4. A compact is formed by molding metal particles made of an iron alloy containing at least one element of silicon and aluminum and having an average particle size of 10 to 400 μm. A surface of metal particles is oxidized to form an iron oxide film containing iron as a main component to form magnetic particles, and thereafter, a molten copper alloy that is a bonding metal that bonds the magnetic particles together while heating the compact. Is impregnated into the voids of the molded body, and subsequently heat-treated to reduce oxygen in the iron oxide film by at least one of silicon and aluminum in the metal particles to form an insulating oxide film containing silicon or aluminum as a main component. A method for producing a soft magnetic material, characterized by being changed. 5. An iron alloy containing at least one element of silicon and aluminum, comprising metal particles having an average particle size of 10 to 400 μm and an iron oxide film mainly composed of iron and surrounding the metal particles. Magnetic particles and particles of a copper alloy, which is a binding metal that binds the magnetic particles together, are formed by pressing and formed into a formed body, and the formed body is subjected to a heat treatment, and silicon, aluminum in the metal particles at least. A method of manufacturing a soft magnetic material, comprising reducing oxygen in the iron oxide film by one to convert it to an insulating oxide film containing silicon or aluminum as a main component. 6. The copper alloy according to claim 3, wherein said copper alloy contains 1 to 5% by weight of at least one of copper oxide, phosphorus, aluminum, zinc, silicon and magnesium, which is more easily oxidized than iron. A method for producing a soft magnetic material according to any one of the preceding claims. 7. The metal particles made of the iron alloy have an aspect ratio (w / t) of 10 when the thickness is t and the width is w.
The method for producing a soft magnetic material according to any one of claims 3 to 6, wherein the soft magnetic material has a plate shape having a width (w) of 10 to 4000 µm.