JP2007270271A - Soft magnetic alloy, its manufacturing method, and magnetic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a software magnetic alloy containing fine crystals of nano-scale, and having the high saturated magnetic flux density, excellent soft magnetic characteristic, and especially excellent AC magnetic characteristic, and its manufacturing method. <P>SOLUTION: The soft magnetic alloy manufacturing method comprises: a step of manufacturing an Fe-based alloy having a structure in which crystal grains having the mean grain size of ≤ 20 nm in an amorphous mother phase are dispersed with the mean crystalline intergranular distance of ≤ 50 nm by quenching a molten alloy containing Fe and metalloid elements; and a step of forming a structure in which crystal grains of the body-centered cubicle structure of the mean grain size of ≤ 50 nm are dispersed at ≥ 30% in terms of the volume fraction in an amorphous mother phase by heating the Fe-based alloy to perform the heat treatment. The soft magnetic alloy is manufactured by using the manufacturing method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes various transformers, reactor / choke coils, noise countermeasure components, pulse power magnetic components used in laser power supplies and accelerators, communication pulse transformers, motor cores, generators, magnetic sensors, antenna cores, current sensors, magnetic Soft magnetic alloy with high saturation magnetic flux density and fine soft magnetic properties including nanoscale fine crystal grains used in shields, electromagnetic wave absorbing sheets, yoke materials, etc., and particularly its production method and magnetism Regarding parts.

  Silicon steel is used as a soft magnetic material for various transformers, motors, generators, reactor choke coils, noise countermeasure parts, laser power supplies, pulse power magnetic parts for accelerators, various sensors, magnetic shields, magnetic circuit yokes, etc. Ferrite, amorphous alloys, FeCuNbSiB alloys and Fe-based nanocrystalline alloys represented by FeZrB alloys are known. Ferrite materials have a low saturation magnetic flux density and a low Curie temperature, so when used in high-power applications such as high-power magnetic cores designed to have a high operating magnetic flux density, the temperature characteristics compared to the problems of large magnetic core size and metal-based soft magnetic materials There is a problem that makes it worse. Silicon steel is advantageous in terms of downsizing in low-frequency applications where the material is inexpensive and magnetic flux density is high, but there is a problem that the core loss is large, especially in high-frequency applications, because the eddy current loss increases, There is a problem that the loss becomes remarkably large. Fe-based and Co-based amorphous alloys (amorphous alloys) are usually manufactured by ultra-rapid cooling from the liquid phase or gas phase, and are essentially free of crystalline magnetic anisotropy due to the absence of crystal grains. It is known to exhibit soft magnetic properties. Amorphous alloys have low loss and high magnetic permeability, and are used as magnetic core materials for power transformers, choke coils, magnetic heads and current sensors. Further, the plate thickness is usually about 5 μm to 50 μm, and since eddy current loss is low, it is suitable for high frequency applications. However, the Fe-based amorphous alloy has a large magnetostriction, and there is a problem of noise, and when impregnated with a resin or the like, there is a problem that magnetic characteristics are deteriorated due to a stress generated by the resin impregnation. In addition, the saturation magnetic flux density is less than 1.7 T when an expensive element such as Co is not added, which is insufficient. Co-based amorphous alloys have low magnetostriction and high magnetic permeability, but the saturation magnetic flux density is as low as 1T or less, and there is a problem that the magnetic core becomes large in applications where DC is superimposed or in low frequency applications. There is a problem that the change with time becomes large. Moreover, since Co is expensive, the use is limited.

Fe-based nanocrystalline alloys are known to exhibit excellent soft magnetic properties comparable to Co-based amorphous alloys and high saturation magnetic flux densities comparable to Fe-based amorphous alloys, such as common mode choke coils. It is used for magnetic cores such as noise countermeasure parts, high-frequency transformers, pulse transformers, and current sensors. Typical composition systems are Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -Si-B alloys and Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) alloys described in JP-B-4-4393 and JP-A-1-242755. -Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -B alloys and the like are known. These Fe-based nanocrystalline alloys are usually produced by rapidly cooling from a liquid phase or a gas phase to form an amorphous alloy and then microcrystallizing it by heat treatment. As a method of quenching from the liquid phase, a single roll method, a twin roll method, a centrifugal quench method, a spinning in spinning solution, an atomizing method, a cavitation method, and the like are known. Further, as a method of quenching from the gas phase, a sputtering method, a vapor deposition method, an ion plating method and the like are known. Fe-based nanocrystalline alloy is a microcrystallized amorphous alloy produced by these methods, and there is almost no thermal instability as found in amorphous alloys. It is known that it exhibits excellent soft magnetic characteristics with a high saturation magnetic flux density and low magnetostriction. Furthermore, nanocrystalline alloys are known to have little change over time and excellent temperature characteristics.
Japanese Examined Patent Publication No. 4-4393 (page 5, right column, lines 31-43, FIG. 1) Japanese Examined Patent Publication No. 1-2242755 (page 3, upper left column 15 to upper right column, fifth line)

However, the saturation magnetic flux density Bs of the Fe-based amorphous alloy is such that when an expensive element such as Co is not added, increasing the amount of Fe to increase the saturation magnetic flux density lowers the Curie temperature. It is difficult for the saturation magnetic flux density Bs to exceed 1.7T, and the Fe-based amorphous alloy has a much lower Bs than silicon steel, so low-frequency applications such as power transformers and excellent DC superposition characteristics are required. In applications such as reactors (power chokes) that are used, there is a problem that the core volume increases.
The silicon steel sheet has a problem from the viewpoint of energy saving because the iron loss is larger than that of the Fe-based amorphous alloy. In addition, silicon steel sheets are inferior in terms of magnetic core loss compared to conventional amorphous alloys and nanocrystalline soft magnetic alloys because eddy current loss increases at high frequencies.
Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -Si-B alloy and Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -B alloy A typical conventional Fe-based nanocrystalline soft magnetic alloy is an alloy that can produce a wide material without adding Co, and the saturation magnetic flux density at room temperature is less than 1.73 T as in the case of an Fe-based amorphous alloy. Since the volume increases, further higher saturation magnetic flux density is desired. Conventional Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -Si-B based alloys and Fe-Cu- (Nb, Ti, Zr, Hf, Mo, W, Ta) -B based An alloy is manufactured by once producing an alloy that is entirely in an amorphous phase as much as possible, and then nanocrystallizing it by the combined effect of elements such as Cu and Nb.
Cu forms a cluster by heat treatment, which becomes a heterogeneous nucleation site of a crystal phase (bcc phase) of a body-centered cubic structure, and further, an element such as Nb stabilizes the amorphous layer, and crystal grains of the bcc phase It is considered that excellent soft magnetic properties can be obtained in order to realize a nanocrystalline alloy in which growth is suppressed and nanocrystalline grains are dispersed. However, in order to increase the saturation magnetic flux density, the amount of Fe must be increased, and the amount of Nb, which is a nonmagnetic element, must be reduced. However, in the conventional manufacturing method in which nanocrystallization is performed by heat treatment after amorphization, there is a problem that when Nb or the like is reduced, crystal grains become coarse and soft magnetic characteristics are greatly deteriorated. The crystal grains generated before the heat treatment have a large crystal grain size and deteriorate the soft magnetic properties after the heat treatment.Therefore, as much as possible, there is no crystal in the alloy before the heat treatment after the rapid cooling, and a completely amorphous state is obtained. It was known that it would be preferable to realize it. For this reason, in order to produce a complete amorphous alloy by a rapid quenching method such as a single roll method, the amount of Fe cannot be increased so much, and there is a limit to achieving both high saturation magnetic flux density and soft magnetic properties. was there.
When an Fe-based amorphous alloy typified by Fe-B or Fe-Si-B system is crystallized, the saturation magnetic flux density increases, but the crystal grains become coarse and the soft magnetism deteriorates significantly. is there.
Further, when the amount of Fe is increased in the Fe-B system or Fe-Si-B system and the crystal material is directly manufactured, the formation of the compound phase and the grain of the Fe phase (bccFe phase) having a body-centered cubic structure are coarsened, There is a problem that soft magnetism cannot be obtained.

As described above, the conventional Fe-based nanocrystalline soft magnetic alloy and Fe-based amorphous alloy have a saturation magnetic flux density of less than 1.73 T, and the high Bs crystal material manufactured by the ultra-quenching method has soft magnetic properties. There is a problem that it is remarkably inferior, it has a higher saturation magnetic flux density than conventional Fe-based nanocrystalline soft magnetic alloys and Fe-based amorphous alloys, lower core loss than a silicon steel sheet, and exhibits excellent soft magnetic properties with high permeability. Realization of a method for producing a soft magnetic alloy is strongly desired.
Therefore, an object of the present invention is to provide a method for producing a soft magnetic alloy exhibiting excellent soft magnetic properties at a high saturation magnetic flux density, particularly excellent alternating magnetic properties.

  The present invention rapidly quenches a molten alloy containing Fe and a metalloid element, and crystal grains having an average grain size of 30 nm or less (not including 0 nm) are contained in the amorphous matrix by a volume fraction in the amorphous matrix. A process for producing an Fe-based alloy having a structure in which the structure is dispersed in an amount of more than 0% and less than 30%, and heat treatment is performed on the Fe-based alloy so that body-centered cubic crystal grains having an average grain size of 50 nm or less are contained in the amorphous matrix. This is a method for producing a soft magnetic alloy comprising a step of forming a structure in which a volume fraction is 30% or more dispersed. The alloy produced by this production method exhibits superior soft magnetic properties, particularly excellent alternating magnetic properties, at a high saturation magnetic flux density than conventional nanocrystalline soft magnetic alloys and amorphous alloys.

When the molten alloy is quenched, an Fe-based alloy with a structure in which grains with an average grain size of 30 nm or less are dispersed in the amorphous matrix in a volume fraction of more than 0% and less than 30% in the amorphous matrix As a result, in a composition with a large amount of Fe in which the crystal grains become coarser, the crystal grain size does not increase significantly even after subsequent heat treatment, which is higher than that of conventional Fe-based nanocrystalline alloys and Fe-based amorphous alloys. It has been found that it exhibits excellent soft magnetic properties while having a saturation magnetic flux density. Conventionally, it was thought that an alloy consisting of a completely amorphous phase was heat treated and crystallized to show excellent soft magnetism. However, as a result of intensive studies, an alloy with a large amount of Fe is completely amorphous. Rather than making an alloy, it is better to heat-treat after producing an alloy in which fine crystal grains are dispersed in an amorphous matrix (matrix). And found that excellent soft magnetic properties can be realized. The average grain size of the crystal grains dispersed in the amorphous matrix before the heat treatment needs to be 30 nm or less.
The reason for this is that if the average grain size exceeds this range before the heat treatment, the soft magnetism deteriorates due to the crystal grains becoming too large or a non-uniform grain structure when the heat treatment is performed. It is. Preferably, the average grain size of the crystal grains dispersed in the amorphous matrix is 20 nm or less. Within this range, more excellent soft magnetic characteristics can be realized. Further, the average distance between crystal grains (the center-to-center distance of each crystal) is usually 50 nm or less. When the average inter-grain distance is large, the crystal grain size distribution of the crystal grains after the heat treatment becomes wide. The body-centered crystal grains dispersed in the amorphous matrix after the heat treatment must have an average particle size of 50 nm or less and a volume fraction of 30% or more. This is because if the average grain size of the crystal grains exceeds 50 nm, the soft magnetic characteristics deteriorate, and if the volume fraction of the crystal grains is less than 30%, the amorphous fraction is large and it is difficult to obtain a high saturation magnetic flux density. A more preferable average grain size of crystal grains is 30 nm or less, and a more preferable volume fraction of crystal grains is 50% or more. Within this range, it is possible to realize an alloy that is more excellent in soft magnetism and has a lower magnetostriction than an Fe-based amorphous alloy.

  In the present invention, when the soft magnetic alloy contains at least one element selected from Cu and Au of 3 atomic% or less, crystal grains having an average grain size of 30 nm or less are present in the amorphous matrix. It is easy to realize a structure in which the volume fraction in the phase is more than 0% and less than 30%. In the case of containing at least one element selected from Cu and Au, an amorphous state cluster or a face-centered cubic structure (fcc structure) with a high Cu or Au concentration is present in the alloy before the heat treatment after quenching. May exist. In particular, when at least one element selected from Cu and Au is more than 1 atomic% and less than 2 atomic%, excellent soft magnetic characteristics can be obtained, and more preferable results can be obtained.

  When the soft magnetic alloy contains 80 atomic% or more of Fe, a soft magnetic alloy having a high saturation magnetic flux density can be produced, and thus a more preferable result can be obtained.

  When the soft magnetic alloy contains at least one metalloid element selected from B, Si, P, C and Ge, it can be amorphized by quenching the molten metal, and in the amorphous matrix It is possible to realize a structure in which crystal grains having an average particle size of 30 nm or less are dispersed in an amorphous matrix at a volume fraction of less than 30%.

The composition of the soft magnetic alloy is represented by a composition formula: Fe _100-xy A _x X _y (atomic%), where A is one or more elements selected from Cu and Au, X is B, Si One or more elements selected from P, C, Ge, 0 ≦ x ≦ 3, 12 ≦ y ≦ 20, high saturation magnetic flux density, and excellent soft magnetic characteristics can be realized. B is an element effective for realizing an excellent soft magnetism at a high saturation magnetic flux density, and a magnetic property superior to a case where B is contained in an amount of 12 atomic% or more and 20 atomic% or less as an X element, and more preferable results are obtained. can get. The sum of the element amounts of A and X is preferably x + y ≦ 20.

  Further, when the amount of A of the soft magnetic alloy is 0.5 ≦ x ≦ 2, crystal grains having an average grain size of 30 nm or less are present in the amorphous matrix before the heat treatment. A structure dispersed with a volume fraction of less than 30% can be easily realized, and particularly excellent soft magnetic properties can be realized after heat treatment, and more preferable results can be obtained. Although the effect of Cu has not been clarified yet, it is thought that Cu clusters or fcc Cu contributes to the formation of bcc Fe crystal grains. Cu clusters or fcc Cu may be heterogeneous nucleation sites.

The above-mentioned manufacturing method shows a soft magnetic property with a saturation magnetic flux density of 1.73 T or more and soft magnetism, excellent soft magnetism at a high saturation magnetic flux density, and low loss soft magnetism with a core loss of 20 W / kg or less at 20 kHz and 0.2 T. An alloy can be realized.
Also, a soft magnetic alloy having a coercive force Hc of 200 A / m or less, and further 100 A / m or less can be realized. In addition, a soft magnetic alloy having an AC ratio initial permeability μk of 3000 or more, further 5000 or more can be realized.

  Further, a part of Fe may be substituted with at least one element selected from Co and Ni. It is possible to control the magnitude of the induced magnetic anisotropy by substituting Co and Ni. A B-H loop with a high squareness ratio and a B-H loop with better linearity can be obtained, and more suitable characteristics can be realized with a saturable reactor magnetic core and a current sensor magnetic core.

In addition, a part of Fe is within a range in which the saturation magnetic flux density does not significantly decrease, Cr, Mn, Zn, As, Se, S, O, N, Sb, Sn, In, Cd, Ag, Bi, Mg, Sc, It may be substituted with at least one element selected from Re, Ag, platinum group elements, Y, and rare earth elements. By substituting these elements, the corrosion resistance can be improved, or the electrical resistivity and magnetic properties can be adjusted and improved.
The crystal phase of the body-centered cubic structure of the soft magnetic alloy produced by the production method of the present invention is mainly Fe, but depending on the alloy composition, Si, B, Al, Ge, Zr, etc. may be dissolved. is there. In addition, a face-centered cubic structure phase (fcc phase) partially containing Cu or Au may exist.

  In the alloy of the present invention produced by the manufacturing method of the present invention, it is desirable that the magnetic core loss is low in the absence of the compound phase, but the compound phase may be partially included.

In the present invention, as a method for rapidly cooling the molten metal, there are a single roll method, a twin roll method, a rotating liquid prevention method, a gas atomization method, a water atomization method, and the like, and a ribbon or powder can be produced. Further, it is desirable that the molten metal temperature at the time of rapid cooling of the molten metal is higher by about 50 ° C. to 300 ° C. than the melting point of the alloy.
The ultra-rapid cooling method such as the single roll method can be performed in the atmosphere or in an atmosphere such as local Ar or nitrogen gas when no active metal is contained, but when active metal is contained, Ar, He, etc. In the inert gas, nitrogen gas or reduced pressure, or by controlling the gas atmosphere near the roll surface at the nozzle tip, the CO ₂ gas is blown onto the roll, or the CO gas is burned near the roll surface near the nozzle. While manufacturing the alloy ribbon.
In the case of the single roll method, the peripheral speed of the cooling roll is desirably in the range of about 15 m / s to 50 m / s, and the cooling roll is made of pure copper, Cu—Be, Cu—Cr, Cu—Zr, Cu, which has good heat conduction. A copper alloy such as -Zr-Cr is suitable. When manufacturing in large quantities, when manufacturing a thin strip with a large plate thickness or a wide strip, it is preferable that the cooling roll has a water cooling structure.

The heat treatment is usually performed in an inert gas such as argon gas, nitrogen gas, or helium. By heat treatment, the volume fraction of crystal grains mainly composed of Fe having a body-centered cubic structure is increased, and the saturation magnetic flux density is increased. Moreover, magnetostriction is also reduced by the heat treatment. The soft magnetic alloy of the present invention can be provided with induced magnetic anisotropy by performing a heat treatment in a magnetic field. The heat treatment in a magnetic field is performed by applying a magnetic field having a strength sufficient to saturate the alloy for at least a part of the heat treatment period. Although it depends on the shape of the alloy magnetic core, generally, a magnetic field of 8 kAm ⁻¹ or more is applied in the longitudinal direction (in the case of an annular core) when applied in the width direction of the ribbon (in the case of an annular core: the height direction of the core). (Magnetic path direction) When applying, apply a magnetic field of 80 Am ⁻¹ or more. As the magnetic field to be applied, any of direct current, alternating current, and repetitive pulse magnetic field may be used. A magnetic field is usually applied for 20 minutes or more in a temperature range of 200 ° C. or more. A better uniaxial induction magnetic anisotropy is imparted when the temperature is increased, maintained at a constant temperature and during cooling, so that a more desirable DC or AC hysteresis loop shape is realized. By applying heat treatment in a magnetic field, an alloy exhibiting a DC hysteresis loop with a high squareness ratio or a low squareness ratio can be obtained. When no heat treatment in a magnetic field is applied, the alloy of the present invention becomes a DC hysteresis loop with a medium squareness ratio. It is desirable to perform the heat treatment in an inert gas atmosphere having a dew point of −30 ° C. or lower. When the heat treatment is performed in an inert gas atmosphere having a dew point of −60 ° C. or lower, the variation is further reduced and more preferable results are obtained. . The maximum temperature reached during the heat treatment is usually in the range of 300 ° C to 600 ° C. In the case of the heat treatment pattern held at a constant temperature, the holding time at the constant temperature is usually 100 hours or less, preferably 4 hours or less from the viewpoint of mass productivity. The average heating rate during the heat treatment is preferably from 0.1 ° C / min to 200 ° C / min, more preferably from 0.1 ° C / min to 100 ° C / min, and the average cooling rate is preferably 0.1 ° C / min. To 3000 ° C./min, more preferably 0.1 ° C./min to 100 ° C./min. In this range, an alloy having a particularly low magnetic core loss can be obtained. The heat treatment is not limited to a single step, and a multi-step heat treatment or a plurality of heat treatments can be performed. Furthermore, the alloy can be heated and heat-treated by passing a direct current, an alternating current or a pulsed current through the alloy. Further, during the heat treatment, the magnetic properties can be improved by heat treatment while applying tension or compressive force.

  Another aspect of the present invention is a soft magnetic alloy produced by the above production method and comprising a structure in which body-centered cubic crystal grains having an average grain size of 50 nm or less are dispersed in an amorphous matrix by a volume fraction of 30% or more It is. The alloy of the present invention exhibits a high saturation magnetic flux density of 1.73 T or more and excellent AC magnetic characteristics with a core loss of 20 W / kg or less at 20 kHz and 0.2 T.

  In the alloy of the present invention, a more preferable average grain size of crystal grains is 30 nm or less, and a more preferable volume fraction of crystal grains is 50% or more. Within this range, it is possible to realize an alloy that is more excellent in soft magnetism and has a lower magnetostriction than an Fe-based amorphous alloy.

The soft magnetic alloy of the present invention is formed by coating the alloy ribbon or powder surface with a powder or film of SiO ₂ , MgO, Al ₂ O _3, etc. as necessary, forming a surface treatment by chemical conversion treatment, and forming an insulating layer. Thus, a treatment such as forming an oxide insulating layer on the surface or forming an organic resin layer and performing interlayer insulation can be performed. By such treatment, the high frequency characteristics are further improved, and a more preferable result can be obtained. This is because, particularly when a magnetic core is manufactured, the effect of eddy currents at high frequencies across layers or particles is reduced, and the magnetic core loss at high frequencies is improved. This effect is particularly remarkable when used in a magnetic core having a good surface state and a wide thin ribbon or a powder magnetic core obtained by solidifying powder.
The soft magnetic alloy of the present invention can be impregnated or coated as necessary. It can be used as a wound core cut core or a laminated core by impregnating with a resin such as an epoxy resin, an acrylic resin, or a polyimide resin, or by bonding an alloy. In general, the magnetic core is used in a resin case or by being coated. Moreover, it may cut | disconnect and it may be set as a cut core. In some cases, a powder magnetic core obtained by crushing the alloy into powder or flakes and solidifying with water glass or resin, or powder or flakes made from the alloy are mixed with a resin to form a sheet. .

  Another aspect of the present invention is a magnetic component using the soft magnetic alloy. Since the soft magnetic alloy of the present invention exhibits low magnetic core loss even at commercial frequencies and relatively low frequencies, it is suitable for transformer iron cores, motor iron cores, reactor iron cores, and the like, and can realize high-performance magnetic parts.

  According to the present invention, it is possible to provide a method for producing a soft magnetic alloy, a soft magnetic alloy and a magnetic component exhibiting a high saturation magnetic flux density and excellent soft magnetic characteristics, particularly excellent AC magnetic characteristics. is there.

EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, this invention is not limited to these.
Example 1
A molten alloy with an alloy composition of Fe _bal. Cu _1.35 B ₁₄ Si ₂ (atomic%) heated to 1250 ° C is ejected from a slit nozzle to a Cu-Be alloy roll with an outer diameter of 300 mm rotating at a peripheral speed of 30 m / s. An alloy ribbon having a width of 5 mm and a thickness of 18 μm was produced. As a result of X-ray diffraction and transmission electron microscope (TEM) observation of the produced alloy ribbon, it was confirmed that the alloy ribbon was composed of a structure in which crystal grains were distributed in the amorphous matrix. FIG. 1 shows a microstructure inside the alloy ribbon observed with a transmission electron microscope, and FIG. 2 shows a schematic diagram of the microstructure inside the alloy ribbon. It was confirmed that fine crystal grains having an average particle diameter of about 5.5 nm were contained in the amorphous matrix (matrix) by a volume fraction of 4.8% from the microstructure by electron microscope observation.
Next, the produced alloy ribbon was wound around an outer diameter of 19 mm and an inner diameter of 15 mm to produce a wound core. This winding core is inserted into a furnace in a nitrogen gas atmosphere and heated from room temperature to 420 ° C at a heating rate of 7.5 ° C / min while applying a magnetic field of 240 KA / m in the height direction of the winding core. After holding for 60 minutes, it was cooled to 200 ° C. at an average cooling rate of 1.2 ° C./min, removed from the furnace, cooled to room temperature, and subjected to heat treatment in a magnetic field. The magnetic properties of the sample after heat treatment were measured. Moreover, the X-ray diffraction and transmission electron microscope (TEM) observation of the heat-processed sample were performed. FIG. 3 shows an X-ray diffraction pattern of the heat-treated sample, FIG. 4 shows a microstructure inside the alloy ribbon observed with a transmission electron microscope, and FIG. 5 shows a schematic diagram of the microstructure inside the alloy ribbon. From the observed microstructure and X-ray diffraction, it was confirmed that fine body-centered cubic crystal grains with an average particle size of about 14 nm were dispersed in the amorphous phase, accounting for 60% of the structure. It was. Further, when the composition of the crystal grains was investigated, it was confirmed that the crystal grains had a body-centered cubic structure (bcc structure) mainly composed of Fe.
Table 1 shows the saturation magnetic flux density Bs, coercive force Hc, AC ratio initial permeability μ _{1k at 1} kHz, magnetic core loss P _{cm at} 20 kHz, 0.2 T, and average grain size D after heat treatment. For comparison, magnetic properties and grain size after heat treatment and crystallization of Fe _bal. B ₁₄ Si ₂ (atomic%) alloy, which was a completely amorphous alloy after quenching the molten alloy D (Comparative Example 1), Fe _bal. Cu ₁ Nb ₃ Si _13.5 B ₉ (atomic%), which is a typical nanocrystalline soft magnetic alloy produced by heat-treating and crystallizing a conventionally known amorphous alloy _. ) Magnetic properties and grain size of alloy (Comparative Example 2) and Fe _bal. Nb ₇ B ₉ (Atom%) alloy (Comparative Example 3), typical Fe-based amorphous alloy Fe _bal. B ₁₃ Si The magnetic characteristics of ₉ alloy (atomic%) (Comparative Example 4) and 6.5 mass% silicon steel strip (50 μm) (Comparative Example 5) are shown.
The alloy produced by the production method of the present invention exhibits a high saturation magnetic flux density Bs of 1.73 T or more, and exhibits a higher Bs than conventional Fe-based amorphous alloys and conventional Fe-based nanocrystalline alloys. In addition, when Fe _bal. Si ₂ B ₁₄ (atomic%) alloy, which was a completely amorphous alloy, is heat-treated and crystallized, the soft magnetism is remarkably inferior, especially the core loss P at 20 kHz, 0.2 T. _cm was too large to be measured because it could not be excited by a normal device. Since the AC ratio initial permeability μ _{1k at} 1 kHz is higher and the core loss Pcm is lower than the conventional 6.5 mass% silicon steel strip, it has characteristics suitable for power choke coils, high frequency transformers, and the like.

As a result of measuring the saturation magnetostriction constant λs of the alloy of the present invention, λs was + 14 × 10 ⁻⁶ . It has been found that the magnetostriction can be reduced to 1/2 or less of the Fe-based amorphous alloy. For this reason, it has been found that when impregnation or adhesion is performed, deterioration of soft magnetic properties can be suppressed as compared with Fe-based amorphous alloys, and it is suitable for power choke coil cut cores and motor core materials.
Next, as a result of trial manufacture and evaluation of a power choke using the alloy of the present invention, it showed a DC superposition characteristic superior to that of a choke coil made from a dust core or an Fe-based amorphous alloy, and realized a high-performance choke coil It was confirmed that it was possible.

(Example 2)
The Bm dependence of the core loss (iron loss) Pcm per unit weight at 50 Hz of the wound core made of the alloy of the present invention shown in Example 1 was measured. The result is shown in FIG. For comparison, the Bm dependence of the core loss Pcm of a conventional grain-oriented electrical steel sheet and an Fe-based amorphous alloy wound core is also shown. The wound core made of the alloy of the present invention manufactured by the manufacturing method of the present invention shows a low magnetic core loss comparable to the wound core made of an Fe-based amorphous alloy and has a high saturation magnetic flux density. The core loss is lower than that of the Fe-based amorphous alloy, and the core loss does not increase rapidly until the magnetic flux density is about 1.65T. For this reason, when used for a transformer or the like, the designed magnetic flux density can be made higher than that of a conventional Fe-based amorphous alloy, and the transformer can be miniaturized. Moreover, since the magnetic core loss is lower than that of the grain-oriented electrical steel sheet up to the high magnetic flux density region, it has excellent performance in terms of energy saving.

(Example 3)
The frequency dependence of the core loss (iron loss) Pcm per unit weight at 0.2 T of the wound core made of the alloy of the present invention shown in Example 1 was measured. The result is shown in FIG. For comparison, the frequency dependence of the core loss Pcm of a conventional 6.5 mass% silicon steel sheet and Fe-based amorphous alloy is also shown. Although the alloy of the present invention is a high-saturation magnetic flux density material and exhibits a lower core loss than conventional Fe-based materials, it should be suitable for magnetic core materials such as reactors, choke coils and transformers used at high frequencies. I understand. Moreover, when the AC ratio initial permeability was measured from 1 kHz to 100 kHz, a value of 6000 or more was obtained up to 100 kHz, and it was confirmed that the high-frequency permeability was higher than that of Fe-based amorphous alloys and 6.5 mass% silicon steel sheets. It was. For this reason, it has been found that it is suitable for various choke coils such as a common mode choke, various transformers such as a pulse transformer, a magnetic shield material, and an antenna core.

Example 4
An alloy ribbon was produced by spraying a molten alloy heated to 1300 ° C having the composition shown in Table 2 onto a Cu-Be alloy roll with an outer diameter of 300 mm rotating at a peripheral speed of 32 m / s. The produced alloy ribbon has a width of 5 mm and a thickness of about 21 μm. As a result of X-ray diffraction and transmission electron microscope (TEM) observation, it was confirmed that the structure was dispersed in the amorphous matrix at a volume fraction of less than 30%.
Next, these produced alloy ribbons were wound to an outer diameter of 19 mm and an inner diameter of 15 mm to prepare a wound core, which was then inserted into a furnace in a nitrogen gas atmosphere, and a temperature increase rate of 8.5 ° C./min from room temperature to 400 ° C. The mixture was heated at 410 ° C. for 60 minutes, cooled to room temperature and cooled. The average cooling rate was estimated to be over 30 ℃ / min. Next, the magnetic properties of the sample after the heat treatment were measured. Further, the heat-treated alloy was subjected to X-ray diffraction and observation with a transmission electron microscope. The average crystal grain size D was estimated from the crystal peak half width of X-ray diffraction. Moreover, as a result of observing the microstructure with a transmission electron microscope, it was confirmed that in each sample, fine crystal grains having a body-centered cubic structure with a particle size of 60 nm or less occupy 30% or more of the structure.
Table 2 shows the saturation magnetic flux density Bs, the coercive force Hc, and the magnetic core loss P _cm at 20 kHz, 0.2 T of the alloy sample after the heat treatment. The saturation magnetic flux density Bs and the characteristics of an alloy manufactured by a manufacturing method different from the present invention are also shown for comparison. The Fe _bal. B ₆ alloy had a high Bs, but there was no amorphous phase before the heat treatment, and the crystal accounted for 100%. The crystal grain size was also estimated to be 100 nm. Since Hc was very large and soft magnetism was inferior, the core loss Pcm was too large, and excitation to the measured magnetic flux density level was difficult, and Pcm could not be measured. Conventional nanocrystalline soft magnetic alloys are once amorphized and then nanocrystallized by heat treatment, and it has been desired to be as completely amorphous as possible before the heat treatment. Fe _bal. Cu ₁ Nb ₃ Si _13.5 B ₉ alloy, which is a typical nanocrystalline soft magnetic alloy, has Bs of 1.24T, Fe _bal. Nb ₇ B ₉ alloy is 1.52T, compared to the alloy produced by the manufacturing method of the present invention. Bs is low. The volume fraction of crystal grains was 75% and 70%, respectively, and the average crystal grain size was 12 nm and 9 nm, respectively. As described above, it has been clarified that the alloy manufactured by the manufacturing method of the present invention can realize an alloy exhibiting excellent soft magnetism while having high Bs.

(Example 5)
A molten alloy with an alloy composition of Fe _bal. Cu _1.35 Si ₂ B ₁₄ (atomic%) heated to 1250 ° C is ejected from a slit-shaped nozzle onto a Cu-Be alloy roll with an outer diameter of 300 mm rotating at a peripheral speed of 30 m / s. An alloy ribbon having a width of 5 mm and a thickness of 18 μm was produced. As a result of X-ray diffraction and transmission electron microscope (TEM) observation of the produced alloy ribbon, it was confirmed that the alloy ribbon was composed of a structure in which crystal grains were distributed in the amorphous matrix. It was confirmed that fine crystal grains having an average particle diameter of about 5.5 nm were distributed in the amorphous matrix (matrix) with an average inter-grain distance of 24 nm from the microstructure by electron microscope observation.
Next, the produced alloy ribbon was cut into 120 mm. This sample was inserted into a tube furnace in a nitrogen gas atmosphere heated in advance, held for 60 minutes, taken out from the furnace and air-cooled, and the dependence of the magnetic properties on the heat treatment temperature was examined. The average cooling rate of the heat treatment was 30 ° C./min or more. Moreover, the X-ray diffraction and transmission electron microscope (TEM) observation of the sample after heat processing were performed. From the observed microstructure and X-ray diffraction, at a heat treatment temperature of 330 ° C. or higher, a fine body-centered cubic crystal grain with an average particle size of 50 nm or less is dispersed in a volume fraction of 30% or more in the amorphous phase. It was confirmed that. Further, when the composition of the crystal grains was investigated, it was confirmed that the crystal grains had a body-centered cubic structure (bcc structure) mainly composed of Fe.
For comparison, a production different from the production method of the present invention was performed for comparison. A molten alloy heated to 1250 ° C with an alloy composition of Fe _bal. Si ₂ B ₁₄ (atomic%) was ejected from a slit-shaped nozzle onto a Cu-Be alloy roll with an outer diameter of 300 mm rotating at a peripheral speed of 33 m / s. An alloy ribbon having a width of 5 mm and a thickness of 18 μm was produced. As a result of X-ray diffraction and transmission electron microscope (TEM) observation of the produced alloy ribbon, it was confirmed that there was no crystal grain and it was an amorphous single phase. Next, the produced alloy ribbon was cut into 120 mm and subjected to the same heat treatment to examine the heat treatment temperature dependence of the magnetic properties.
FIG. 8 shows the heat treatment temperature dependence of the saturation magnetic flux density Bs, and FIG. 9 shows the heat treatment temperature dependence of the coercive force Hc. In the production method of the present invention, when the temperature exceeds 330 ° C., Bs rises, Hc does not increase, and a soft magnetic alloy exhibiting high Bs and excellent soft magnetism is realized at a heat treatment temperature centered at 420 ° C. On the other hand, when an amorphous single-phase alloy is heat-treated, Hc increases rapidly due to crystallization, and good soft magnetism cannot be obtained.
As described above, an alloy having a structure in which a crystal grain having an average grain size of 30 nm or less in the amorphous matrix is distributed to a volume fraction of 30% or less and an average crystal grain distance of 50 nm or less is heat-treated, and the average An alloy mainly composed of Fe produced by the production method of the present invention having a structure in which body-centered cubic structure grains having a particle size of 50 nm or less are dispersed in a volume fraction of 30% or more in an amorphous matrix is excellent in high Bs. It has been found that it exhibits soft magnetism.

(Example 6)
A molten alloy with an alloy composition of Fe _bal. Cu _1.25 Si ₂ B ₁₄ (atomic%) heated to 1250 ° C is ejected from a slit-shaped nozzle onto a rotating Cu-Be alloy roll with a diameter of 300 mm. Alloy ribbons with different grain volume fractions in the crystalline matrix were prepared, and the grain volume fractions were determined from transmission electron microscope images. Next, this alloy ribbon was wound around an outer diameter of 19 mm and an inner diameter of 15 mm to produce a wound core, which was heat-treated at 4 ° C. for 1 hour, and the saturated magnetic flux density Bs and coercive force Hc after the heat treatment were measured. The crystal grain volume fraction of the alloy after the heat treatment was 30% or more, and Bs was 1.8T to 1.87T.
Table 3 shows the Hc after the heat treatment. When an alloy having no crystal grains in the alloy before the heat treatment was heat treated so that the crystal grains in the amorphous matrix were 60% after the heat treatment, the coercive force Hc was remarkably increased to 750 A / m. When heat treatment is performed on an alloy whose volume fraction of crystal grains in the amorphous matrix before heat treatment is less than 30%, Hc after heat treatment is small, and the present manufacturing method realizes an alloy with high Bs and excellent soft magnetism. It was confirmed that it was possible. In contrast, in an alloy in which the volume fraction of crystal grains in the amorphous matrix before heat treatment is 30% or more and the remaining amorphous phase is crystallized, the coarsened crystal grains are It has been found that it tends to increase and Hc tends to increase.
As described above, a high Bs material with a large amount of Fe is heat-treated with an alloy having a structure in which fine crystal grains are dispersed in an amount of more than 0% and less than 30% in a rapidly cooled state before heat treatment, and further crystallization of the alloy It has been found that soft magnetism is superior to an alloy in a completely amorphous state or an alloy having 30% or more of crystal grains.

  According to the present invention, it is possible to provide a soft magnetic alloy manufacturing method, a soft magnetic alloy and a magnetic component which exhibit a saturation magnetic flux density and excellent soft magnetic characteristics, particularly excellent AC magnetic characteristics, and the effects are remarkable.

It is the figure which showed an example of the microstructure inside the alloy ribbon observed by the transmission electron microscope (TEM) of the alloy after quenching the molten alloy concerning this invention. It is a schematic diagram of the microstructure inside the alloy ribbon after quenching the molten alloy according to the present invention. It is the figure which showed an example of the X-ray-diffraction pattern of the alloy after the heat processing manufactured by this invention. It is the figure which showed an example of the microstructure observed with the transmission electron microscope of the alloy after the heat processing manufactured by this invention. It is the figure which showed an example of the microstructure observed with the transmission electron microscope of the alloy after the heat processing manufactured by this invention. FIG. 6 is a diagram showing an example of Bm dependence of a core loss (iron loss) Pcm per unit weight at 50 Hz of a wound core made of an alloy of the present invention and a magnetic core made of a conventional material. FIG. 4 is a diagram showing an example of frequency dependence of a core loss (iron loss) Pcm per unit weight at 0.2 T of a wound core made of an alloy of the present invention and a magnetic core made of a conventional material. It is the figure which showed an example of the heat processing temperature dependence of the saturation magnetic flux density Bs of the alloy which concerns on this invention, and the alloy of the manufacturing method which is not this invention manufacturing method. It is the figure which showed an example of the heat treatment temperature dependence of the coercive force Hc of the alloy which concerns on this invention, and the alloy of the manufacturing method which is not this invention manufacturing method.

Claims (10)

The alloy melt containing Fe and metalloid elements is quenched, and crystal grains with an average grain size of 30 nm or less (not including 0 nm) in the amorphous matrix are more than 0% in volume fraction in the amorphous matrix. A process for producing an Fe-based alloy having a structure dispersed at less than%, and heat-treating the Fe-based alloy so that body-centered cubic crystal grains having an average grain size of 50 nm or less are contained in an amorphous matrix at a volume fraction. A method for producing a soft magnetic alloy comprising a step of forming a structure in which 30% or more is dispersed. The method for producing a nanocrystalline soft magnetic alloy according to claim 1, wherein the soft magnetic alloy contains at least one element selected from Cu and Au of 3 atomic% or less. 3. The method for producing a soft magnetic alloy according to claim 1, wherein the soft magnetic alloy contains 80 atomic% or more of Fe. 4. The method for producing a soft magnetic alloy according to claim 1, wherein the soft magnetic alloy contains at least one metalloid element selected from B, Si, P, C and Ge. . The composition of the soft magnetic alloy is represented by a composition formula: Fe _100-xy A _x X _y (atomic%), where A is one or more elements selected from Cu and Au, X is B, Si The soft magnetic alloy according to claim 1, wherein one or more elements selected from the group consisting of P, C, Ge, 0 ≦ x ≦ 3, and 12 ≦ y ≦ 20. Production method. 6. The method for producing a soft magnetic alloy according to claim 5, wherein the A amount x of the soft magnetic alloy is 0.5 ≦ x ≦ 2. A structure produced by the production method according to any one of claims 1 to 6, wherein body-centered cubic crystal grains having an average grain size of 50 nm or less are dispersed in an amorphous matrix by 30% or more by volume fraction A soft magnetic alloy comprising: The soft magnetic alloy according to claim 7, wherein a saturation magnetic flux density is 1.73 T or more. The soft magnetic alloy according to claim 7 or 8, wherein the core loss at 20kHz, 0.2T is 20 W / kg or less. A magnetic part using the soft magnetic alloy according to claim 7.