Method for producing soft magnetic alloy powder, soft magnetic alloy powder, dust core, magnetic element, and electronic device

Abstract

To provide a soft magnetic alloy powder having a low coercive force, a method for producing a soft magnetic alloy powder capable of stably producing such a soft magnetic alloy powder, a dust core including the soft magnetic alloy powder, a magnetic element including the dust core, and an electronic device including the magnetic element.SOLUTION: A method for producing a soft magnetic alloy powder includes: a step of producing an amorphous alloy powder that has an average particle diameter of 10.0 μm or more and 45.0 μm or less and that is formed of a composition represented by FexCuaNbb(Si1-yBy)100-x-a-b [0.3≤a≤2.0, 2.0≤b≤4.0, and 72.5≤x<75.5 are satisfied, and y is a number that satisfies f(x)≤y≤0.99, and f(x)=(4×10-34)x17.56]; and a step of heating at a temperature of 500°C or higher and 600°C or lower to produce a soft magnetic alloy powder containing 30 vol.% or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less, wherein the volume resistivity of a green compact is 10.0×10-3 [Ω cm] or less.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing soft magnetic alloy powder, soft magnetic alloy powder, compacted magnetic cores, magnetic elements, and electronic devices.

Background Art

[0002] Patent Document 1 discloses soft magnetic powder containing amorphous metal particles having a composition represented by the compositional formula Fe 100-a-b-c-d-e-f-g Cr a Si b B c C d Al e Ti f Co g [However, a, b, c, d, e, f, and g are numbers representing atomic percentages, and satisfy 0 < a ≤ 3.0, 5.0 ≤ b ≤ 15.0, 7.0 ≤ c ≤ 15.0, 0.1 ≤ d ≤ 3.0, 0 < e ≤ 0.016, 0 < f ≤ 0.009, 0 ≤ g ≤ 0.025.] According to such a configuration, soft magnetic powder having good magnetic properties due to the amorphous alloy and low coercive magnetization can be obtained.

[0003] Also, Patent Document 1 discloses that heat treatment is performed in the production of soft magnetic powder. By performing heat treatment, various defects and anisotropy (stress-induced anisotropy) introduced when manufacturing soft magnetic powder can be reduced. Thereby, low coercive magnetization can be achieved. Furthermore, Patent Document 1 discloses that the heating temperature in the heat treatment is set to a temperature lower than the crystallization temperature of the amorphous metal particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, from the viewpoint of ensuring further low coercivity magnetization, the method for producing soft magnetic powder described in Patent Document 1 still has room for improvement. For example, even when heat treatment is performed, the coercivity may not sufficiently decrease in some particles. Therefore, an improvement in the production method is an issue so that the coercivity can be more reliably decreased without impairing the production efficiency of the soft magnetic powder.

Means for Solving the Problems

[0006] The method for producing a soft magnetic alloy powder according to an application example of the present invention is a composition formula Fe represented by an atomic ratio x Cu a Nb b (Si 1-y B y ) 100-x-a-b [where a, b, and x are 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 72.5 ≤ x < 75.5 are satisfied. Also, y is a number satisfying f(x) ≤ y ≤ 0.99, where f(x) = (4 × 10 -34 )x 17.56 ).] a powder production step of producing an amorphous alloy powder composed of the composition and impurities as described above and having an average particle diameter of 10.0 μm or more and 45.0 μm or less, a heat treatment step of crystallizing the amorphous alloy powder by performing heat treatment on the amorphous alloy powder at a temperature of 500°C or more and 600°C or less to produce a soft magnetic alloy powder containing 30% by volume or more of crystal grains having a crystal grain diameter of 1.0 nm or more and 30.0 nm or less, and when the soft magnetic alloy powder is pressurized at a pressure of 63.7 MPa to produce a green compact having a mass of 7.0 g, the volume resistivity of the green compact is 10.0 × 10 -3 [Ω·cm] or less.

[0007] The soft magnetic alloy powder according to an application example of the present invention is a composition formula Fe represented by an atomic ratiox Cu a Nb b (Si 1-y B y ) 100-x-a-b [a, b, and x are numbers with units of atomic %, and 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 72.5 ≤ x < 75.5 are satisfied. Also, y is a number that satisfies f(x) ≤ y ≤ 0.99, where f(x) = (4 × 10 -34 )x 17.56 .] composed of the composition and impurities of having an average particle size of 10.0 μm or more and 45.0 μm or less, containing 30% by volume or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less, when a compacted powder with a mass of 7.0 g is produced by being pressed at a pressure of 63.7 MPa, the volume resistivity of the compacted powder is 10.0 × 10 -3 [Ω·cm] or less.

[0008] The compacted powder core according to the application example of the present invention contains the soft magnetic alloy powder according to the application example of the present invention.

[0009] The magnetic element according to the application example of the present invention includes the compacted powder core according to the application example of the present invention.

[0010] The electronic device according to the application example of the present invention includes the magnetic element according to the application example of the present invention.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0012] Hereinafter, a method for manufacturing a soft magnetic alloy powder, the soft magnetic alloy powder, a powder compact core, a magnetic element, and an electronic device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

[0013] 1. Soft magnetic alloy powder First, the soft magnetic alloy powder according to the embodiment will be described.

[0014] The soft magnetic alloy powder can be applied to any use, and for example, it is used for manufacturing a powder compact core. The powder compact core is manufactured by binding and molding particles of the soft magnetic alloy powder.

[0015] The soft magnetic alloy powder according to the embodiment has a composition formula Fe represented by an atomic ratio x Cu a Nb b (Si 1-y B y ) 100-x-a-b and impurities. a, b, x satisfy 0.3 ≦ a ≦ 2.0, 2.0 ≦ b ≦ 4.0, 72.5 ≦ x < 75.5. Also, y is a number satisfying f(x) ≦ y ≦ 0.99, and f(x) = (4 × 10 -34 )x 17.56 .

[0016] In addition, the soft magnetic alloy powder according to the embodiment has an average particle size of 10.0 μm or more and 45.0 μm or less.

[0017] Furthermore, the soft magnetic alloy powder according to the embodiment contains 30% by volume or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less. These crystal grains are formed by subjecting the amorphous alloy powder, which is a precursor, to heat treatment under predetermined conditions during the production of the soft magnetic alloy powder to cause crystallization.

[0018] When the soft magnetic alloy powder formed through such heat treatment is pressed under a pressure of 63.7 MPa to produce a compacted body with a mass of 7.0 g, the volume resistivity of the compacted body is 10.0×10 -3 [Ω·cm] or less.

[0019] By configuring the volume resistivity of the compacted body to be within the above range, a soft magnetic alloy powder with a low coercive force can be obtained. Also, when the volume resistivity of the above compacted body is within the above range, the variation in the coercive force of the soft magnetic alloy powder can be suppressed. That is, the soft magnetic alloy powder configured such that the volume resistivity of the above compacted body is within the above range can be said to have homogeneity that can greatly suppress the variation in each measured value when, for example, it is divided into a plurality of particle groups and the coercive force of each is measured. In other words, such a soft magnetic alloy powder can be said to be a powder in which each particle stably enjoys the effect of heat treatment and achieves a low coercive force. Therefore, by manufacturing products such as compacted magnetic cores using such a soft magnetic alloy powder, products with stable characteristics can be manufactured with little individual difference.

[0020] 1.1. Composition Hereinafter, the composition of the soft magnetic alloy powder will be described in detail. As described above, the soft magnetic alloy powder according to the embodiment has a composition represented by the composition formula Fe x Cu a Nb b (Si 1-y B y ) 100-x-a-b . This composition formula represents the ratio in terms of the number of atoms in the composition consisting of the five elements Fe, Cu, Nb, Si, and B.

[0021] Fe (iron) has a great influence on the basic magnetic properties and mechanical properties of the soft magnetic alloy powder according to the embodiment.

[0022] The content x of Fe is set to be 72.5 atomic % or more and less than 75.5 atomic %, preferably 72.8 atomic % or more and 75.0 atomic % or less, and more preferably 73.0 atomic % or more and 74.5 atomic % or less. Note that if the content x of Fe is less than the lower limit value, the saturation magnetic flux density of the soft magnetic alloy powder may decrease. On the other hand, if the content x of Fe exceeds the upper limit value, it is impossible to stably form an amorphous structure during the production of the soft magnetic alloy powder, so it may be difficult to form crystal grains having a fine particle size as described above. In addition, the coercive force of the soft magnetic alloy powder may increase.

[0023] Cu (copper) tends to be separated from Fe when producing the soft magnetic alloy powder according to the embodiment from raw materials. For this reason, including Cu causes fluctuations in the composition, and regions that are likely to crystallize partially occur in the particles. As a result, the precipitation of the relatively easily crystallized body-centered cubic lattice Fe phase is promoted, and it becomes easier to form crystal grains.

[0024] The content a of Cu is set to be 0.3 atomic % or more and 2.0 atomic % or less, preferably 0.5 atomic % or more and 1.5 atomic % or less, and more preferably 0.7 atomic % or more and 1.3 atomic % or less. Note that if the content a of Cu is less than the lower limit value, the refinement of crystal grains may be impaired, and there is a possibility that crystal grains having a particle size within the above-described range cannot be formed. On the other hand, if the content a of Cu exceeds the upper limit value, the mechanical properties of the particles may deteriorate and become brittle.

[0025] Nb (niobium) contributes to the refinement of crystal grains together with Cu when heat treatment is performed. For this reason, it is possible to easily form crystal grains having a fine particle size as described above.

[0026] The content ratio b of Nb is set to be 2.0 atomic % or more and 4.0 atomic % or less, preferably 2.5 atomic % or more and 3.5 atomic % or less, and more preferably 2.7 atomic % or more and 3.3 atomic % or less. When the content ratio b of Nb is less than the lower limit value, the refinement of crystal grains may be impaired, and there is a possibility that crystal grains having a particle size within the above-described range cannot be formed. On the other hand, when the content ratio b of Nb exceeds the upper limit value, the mechanical properties of the particles may deteriorate and become brittle. There is also a possibility that the magnetic permeability of the soft magnetic alloy powder decreases.

[0027] Si (silicon) promotes amorphization when manufacturing the soft magnetic alloy powder according to the embodiment from raw materials. Therefore, when manufacturing the soft magnetic alloy powder according to the embodiment, once a homogeneous amorphous structure is formed, and then by crystallizing it, it becomes easier to form crystal grains with a more uniform particle size. And the uniform particle size contributes to the averaging of the magnetocrystalline anisotropy in each crystal grain, so that the coercive force can be reduced and the magnetic permeability can be increased, contributing to the improvement of soft magnetism.

[0028] B (boron) promotes amorphization when manufacturing the soft magnetic alloy powder according to the embodiment from raw materials. Therefore, when manufacturing the soft magnetic alloy powder according to the embodiment, once a homogeneous amorphous structure is formed, and then by crystallizing it, it becomes easier to form crystal grains with a more uniform particle size. And the uniform particle size contributes to the improvement of soft magnetism. Further, by using Si and B in combination, based on the difference in atomic radius between the two, amorphization can be promoted synergistically.

[0029] Here, when the total content ratio of Si and B is set to 1 and the ratio of the content ratio of B to this total is y, the ratio of the content ratio of Si to the total is 1 - y.

[0030] This y is a number that satisfies f(x) ≤ y ≤ 0.99. And the function f(x) of x is f(x)=(4×10 -34 )x 17.56 is.

[0031] FIG. 1 is a diagram showing regions A to C representing the composition of soft magnetic alloy powder according to an embodiment in a two-axis orthogonal coordinate system where x is the horizontal axis and y is the vertical axis.

[0032] In FIG. 1, region C is inside the solid line drawn in the orthogonal coordinate system. Specifically, region C is a closed region surrounded by three straight lines and one curve drawn when the (x, y) coordinates satisfying the four equations of x = 72.5, x = 75.5, y = f(x), and y = 0.99 are plotted in the orthogonal coordinate system, but does not include the points on the line x = 75.5.

[0033] Also, y is preferably a number satisfying f’(x) ≦ y ≦ 0.97. f’(x) is f’(x) = (4×10 -29 )x 14.93 where.

[0034] In FIG. 1, region B is inside the dashed line drawn in the orthogonal coordinate system. Specifically, region B is a closed region surrounded by three straight lines and one curve drawn when the (x, y) coordinates satisfying the four equations of x = 72.8, x = 75.0, y = f’(x), and y = 0.97 are plotted in the orthogonal coordinate system.

[0035] Furthermore, y is more preferably a number satisfying f”(x) ≦ y ≦ 0.95. f”(x) is f”(x) = (4×10 -29 )x 14.93 + 0.05.

[0036] In FIG. 1, region A is inside the dotted line drawn in the orthogonal coordinate system. Specifically, region A corresponds to a closed region surrounded by three straight lines and one curve drawn when the (x, y) coordinates satisfying the four equations of x = 73.0, x = 74.5, y = f”(x), and y = 0.95 are plotted in the orthogonal coordinate system.

[0037] When the soft magnetic alloy powder whose composition is included in region C is manufactured, a homogeneous amorphous structure can be formed with a high probability. Therefore, by crystallizing it, crystal grains with particularly uniform and fine particle sizes can be formed. As a result, soft magnetic alloy powder with a sufficiently reduced coercive force and increased magnetic permeability is obtained.

[0038] Also, the soft magnetic alloy powder whose composition is included in region C can enable the formation of uniform crystal grains even when the Fe content is sufficiently increased. As a result, soft magnetic alloy powder with sufficiently increased magnetic permeability and saturation magnetic flux density is obtained.

[0039] In addition, when the value of y is smaller than region C, since the balance between the Si content and the B content is disrupted, it becomes difficult to form a homogeneous amorphous structure when the soft magnetic alloy powder is manufactured. Therefore, crystal grains with a minute particle size cannot be formed, and the coercive force cannot be sufficiently reduced.

[0040] On the other hand, even when the value of y is larger than region C, since the balance between the Si content and the B content is disrupted, it becomes difficult to form a homogeneous amorphous structure when the soft magnetic alloy powder is manufactured. Therefore, crystal grains with a minute particle size cannot be formed, and the coercive force cannot be sufficiently reduced.

[0041] In addition, the lower limit value of y is preferably 0.30 or more, more preferably 0.45 or more, and even more preferably 0.55 or more. Thereby, further increase in the saturation magnetic flux density and magnetic permeability of the soft magnetic alloy powder can be achieved.

[0042] Also, particularly in region B and region A, by suppressing the Fe content, it is possible to achieve low coercive force while suppressing a decrease in the magnetic permeability of the soft magnetic alloy powder.

[0043] The total of the Si content and the B content, (100 - x - a - b), is not particularly limited, but is preferably 15.0 atomic % or more and 24.0 atomic % or less, more preferably 18.0 atomic % or more and 23.5 atomic % or less, and still more preferably 20.0 atomic % or more and 23.0 atomic % or less. When (100 - x - a - b) is within the above range, crystal grains with a particularly uniform particle size can be formed in the soft magnetic alloy powder.

[0044] Note that y(100 - x - a - b) corresponds to the B content in the soft magnetic alloy powder. y(100 - x - a - b) is appropriately set in consideration of the coercive force, saturation magnetic flux density, etc. as described above, but preferably satisfies 5.0 ≤ y(100 - x - a - b) ≤ 17.0, more preferably satisfies 7.0 ≤ y(100 - x - a - b) ≤ 16.0, and still more preferably satisfies 8.0 ≤ y(100 - x - a - b) ≤ 15.0.

[0045] As a result, a soft magnetic alloy powder containing B (boron) at a relatively high concentration can be obtained. Even when the Fe content of such a soft magnetic alloy powder is high, it is possible to form a homogeneous amorphous structure during its production. Therefore, by subsequent heat treatment, crystal grains with a fine particle size and relatively uniform particle size can be formed, and while sufficiently reducing the coercive force, it is possible to increase the magnetic flux density and permeability.

[0046] When y(100 - x - a - b) is less than the above lower limit, since the B content becomes small, depending on the overall composition when producing the soft magnetic alloy powder, there is a possibility that amorphization becomes difficult. As a result, there is a possibility that reducing the coercive force is inhibited. On the other hand, when y(100 - x - a - b) exceeds the above upper limit, the B content increases and the Si content relatively decreases, so there is a possibility that the permeability of the soft magnetic alloy powder decreases and the saturation magnetic flux density decreases.

[0047] The soft magnetic alloy powder according to the embodiment is the above-described Fe x Cu a Nb b (Si1-y B y ) 100-x-a-b In addition to the composition represented by, it may contain impurities. Examples of the impurities include all elements other than the above, but the total content rate of the impurities is preferably 0.50 atomic% or less. Within this range, since the impurities are less likely to inhibit the effects of this embodiment, their inclusion is allowed.

[0048] The content rate of each element of the impurities is preferably 0.05 atomic% or less respectively. Within this range, since the impurities are less likely to inhibit the effects of this embodiment, their inclusion is allowed.

[0049] As described above, the composition and impurities of the soft magnetic alloy powder according to the embodiment have been explained. The composition and impurities are specified by the following analysis methods.

[0050] Examples of the analysis methods include, for example, the atomic absorption spectrometry for iron and steel specified in JIS G 1257:2000, the ICP emission spectrometry for iron and steel specified in JIS G 1258:2007, the spark discharge emission spectrometry for iron and steel specified in JIS G 1253:2002, the fluorescent X-ray analysis method for iron and steel specified in JIS G 1256:1997, the gravimetric, titrimetric, and absorptiometric methods specified in JIS G 1211~G 1237, etc.

[0051] Specifically, for example, a solid emission spectrometry apparatus manufactured by SPECTRO, particularly a spark discharge emission spectrometry apparatus, model: SPECTROLAB, type: LAVMB08A, and an ICP apparatus CIROS120 type manufactured by Rigaku Corporation can be mentioned.

[0052] In particular, when specifying C (carbon) and S (sulfur), the oxygen flow combustion (high-frequency induction heating furnace combustion)-infrared absorption method specified in JIS G 1211:2011 is also used. Specifically, a carbon and sulfur analyzer, CS-200, manufactured by LECO Corporation can be mentioned.

[0053] In addition, especially when specifying N (nitrogen) and O (oxygen), the nitrogen quantification method for iron and steel specified in JIS G 1228:1997 and the general oxygen quantification method for metallic materials specified in JIS Z 2613:2006 are also used. Specifically, an oxygen / nitrogen analyzer, TC-300 / EF-300 manufactured by LECO Corporation can be mentioned.

[0054] 1.2. Crystal grains The particles of the soft magnetic alloy powder according to the embodiment have crystal grains with a particle size of 1.0 nm or more and 30.0 nm or less.

[0055] These crystal grains are composed of, for example, Fe-Si crystals. Fe-Si crystals have the characteristic of high saturation magnetic flux density peculiar to the Fe-Si based composition. By achieving refinement and uniform particle size of the crystal grains containing Fe-Si crystals, the number density of the crystal grains increases, so that the saturation magnetic flux density of the crystal grains hardly decreases even when refined. Therefore, a high saturation magnetic flux density can be realized in the soft magnetic alloy powder.

[0056] In addition, in the particles, since the crystal grains are refined, the magnetocrystalline anisotropy in the crystal grains is easily averaged. Therefore, even when the Fe concentration is high, an increase in coercive force can be suppressed. Therefore, low coercivity can be achieved in the particles. Also, when many such crystal grains are contained, the magnetic permeability of the particles increases.

[0057] From the above, it is possible to achieve low coercivity while increasing the saturation magnetic flux density and magnetic permeability of the particles.

[0058] In the particles, the content ratio of crystal grains is 30% by volume or more, preferably 40% by volume or more and 99% by volume or less, and more preferably 55% by volume or more and 95% by volume or less. When the content ratio of crystal grains is below the lower limit value, since the ratio of crystal grains decreases, the averaging of the magnetocrystalline anisotropy becomes insufficient, and there is a risk that the magnetic permeability of the soft magnetic alloy powder decreases or the coercive force increases. There is also a risk that the saturation magnetic flux density decreases or the iron loss of the compacted magnetic core increases. On the other hand, although the content ratio of crystal grains may exceed the upper limit value, it is considered that the content ratio of crystal grain boundaries described later decreases instead. Then, a situation in which crystal grains are likely to grow rapidly occurs, and there is a risk that the crystal grains are likely to coarsen due to a slight deviation in the heat treatment temperature or the like. As a result, there is a risk that the magnetic permeability of the soft magnetic alloy powder decreases and the coercive force increases.

[0059] The content ratio of crystal grains is a volume ratio, but since it is considered to be approximately equal to the area ratio occupied by crystal grains with respect to the area of the cross section, the area ratio may be regarded as the content ratio. Therefore, the content ratio of crystal grains is determined as the ratio of the area occupied by crystal grains to the total area in the above-described range in the observation image.

[0060] The particle size of crystal grains is determined by observing the cross section of the particles with an electron microscope and reading from a range of 200 nm square centered at a depth of 5 μm from the surface in the observation image. In this method, a perfect circle having the same area as the area of the crystal grain can be assumed, and the diameter of the perfect circle, that is, the equivalent circle diameter can be used as the particle size of the crystal grain. For the electron microscope, for example, STEM (scanning transmission electron microscope) is used.

[0061] Also, the average particle size is obtained by averaging the particle sizes of the read crystal grains. The average particle size of crystal grains is preferably 2.0 nm or more and 25.0 nm or less, and more preferably 5.0 nm or more and 20.0 nm or less. Thereby, the above effects, that is, the effect that the coercive force is low and the magnetic permeability is high, and the effect that the saturation magnetic flux density is high and the iron loss of the compacted magnetic core is low, become more prominent. The average particle size of crystal grains is calculated from 10 or more particle sizes.

[0062] Note that the particles may contain crystal grains with a particle size outside the above-described range, that is, crystal grains with a particle size of less than 1.0 nm or more than 30.0 nm.

[0063] In addition, whether the crystal grains contain Fe—Si crystals can be specified by EDX (energy dispersive X-ray spectroscopy) analysis using STEM. Specifically, first, an observation image is obtained by STEM for the cross section of the particle. Crystal grains are specified from this observation image. Next, EDX analysis using STEM is performed, and quantitative analysis of each element is performed by a quantification method from the analysis results. If the Fe concentration is the highest and then the Si concentration is high in terms of the atomic ratio in the crystal grains, it can be said that Fe—Si crystals are contained.

[0064] Note that, for example, JEM-ARM200F manufactured by JEOL Ltd. can be used for STEM. In addition, NSS7 manufactured by Thermo Fisher Scientific Inc. can be used for the EDX analyzer. Note that the acceleration voltage during analysis is 120 kV, and Cliff-Lorimer (MBTS) that does not take absorption correction into account is used for the quantification method using the EDX spectrum.

[0065] 1.3. Various characteristics The average particle size of the soft magnetic alloy powder is 10.0 μm or more and 45.0 μm or less, preferably 15.0 μm or more and 40.0 μm or less, and more preferably 20.0 μm or more and 30.0 μm or less. By using such soft magnetic alloy powder with an average particle size, the path through which eddy currents flow can be shortened, so that a compacted powder core capable of sufficiently suppressing the eddy current loss generated in the particles can be manufactured.

[0066] In particular, when the average particle size of the soft magnetic alloy powder is equal to or greater than the lower limit value, a high compacted powder molding density can be achieved by mixing with a soft magnetic powder having an average particle size smaller than that of the soft magnetic alloy powder according to the embodiment.

[0067] The average particle size of the soft magnetic alloy powder is determined as the particle size D50 at which the cumulative percentage from the smaller diameter side reaches 50% in the volume-based particle size distribution obtained by the laser diffraction method.

[0068] If the average particle size of the soft magnetic alloy powder is below the lower limit value, the soft magnetic alloy powder becomes too fine, and thus the fillability of the soft magnetic alloy powder may easily decrease. As a result, the molding density of the compacted powder core, which is an example of a compacted body, may decrease, and there is a risk that the saturation magnetic flux density and magnetic permeability of the compacted powder core may decrease. Also, there is a risk of crystallization by heat treatment. On the other hand, if the average particle size of the soft magnetic alloy powder exceeds the upper limit value, the particle size becomes too large, and in the amorphous alloy powder, which is the precursor of the soft magnetic alloy powder, there is a risk that sufficient amorphization may not be achieved. Also, the relaxation of stress strain by heat treatment becomes insufficient, and there is a risk that low coercivity magnetization becomes difficult.

[0069] Regarding the soft magnetic alloy powder, in the volume-based particle size distribution obtained by the laser diffraction method, when the particle size at which the cumulative percentage from the smaller diameter side reaches 10% is defined as D10 and the particle size at which the cumulative percentage from the smaller diameter side reaches 90% is defined as D90, (D90 - D10) / D50 is preferably about 1.0 or more and 2.5 or less, and more preferably about 1.2 or more and 2.3 or less. (D90 - D10) / D50 is an index indicating the degree of spread of the particle size distribution, and when this index is within the above range, the fillability of the soft magnetic alloy powder becomes good. For this reason, a compacted body with particularly high magnetic properties such as magnetic permeability and saturation magnetic flux density can be obtained.

[0070] The coercive force of the soft magnetic alloy powder is preferably 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less, more preferably 15.9 [A / m] (0.2 [Oe]) or more and 63.7 [A / m] (0.8 [Oe]) or less, and even more preferably 23.9 [A / m] (0.3 [Oe]) or more and 47.8 [A / m] (0.6 [Oe]) or less. By using a soft magnetic alloy powder with such a small coercive force, a compacted powder core with sufficiently suppressed hysteresis loss can be manufactured.

[0071] In addition, when the coercive force is lower than the lower limit value, it becomes difficult to stably manufacture such soft magnetic alloy powder with low coercive force. Moreover, if the pursuit of coercive force goes too far, it may affect the magnetic permeability. On the other hand, when the coercive force exceeds the upper limit value, since the hysteresis loss increases, there is a possibility that the iron loss of the compacted magnetic core increases.

[0072] The coercive force of the soft magnetic alloy powder can be measured, for example, by a vibrating sample magnetometer such as TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd.

[0073] Assuming that the maximum magnetization of the soft magnetic alloy powder is Mm [emu / g] and the true density of the particles is ρ [g / cm 3 , the saturation magnetic flux density Bs [T] obtained by 4π / 10000×ρ×Mm = Bs is preferably 1.0 [T] or more, and more preferably 1.1 [T] or more. By using such soft magnetic alloy powder with a high saturation magnetic flux density, a compacted magnetic core that is difficult to saturate even at a high current can be realized.

[0074] For the measurement of the true density ρ of the soft magnetic alloy powder, a fully automatic gas replacement type densitometer, AccuPyc1330 manufactured by Micromeritics, is used. Also, for the measurement of the maximum magnetization Mm of the soft magnetic alloy powder, a vibrating sample magnetometer, a VSM system manufactured by Tamagawa Seisakusho Co., Ltd., TM-VSM1230-MHHL is used.

[0075] 2. Manufacturing method of soft magnetic alloy powder Next, a method for manufacturing the soft magnetic alloy powder according to the embodiment will be described. FIG. 2 is a process diagram showing the configuration of the manufacturing method of the soft magnetic alloy powder according to the embodiment. The manufacturing method of the soft magnetic alloy powder shown in FIG. 2 includes a powder manufacturing step S102 and a heat treatment step S104.

[0076] 2.1. Powder manufacturing step In the powder manufacturing step S102, powder (amorphous alloy powder) before heat treatment is manufactured.

[0077] The amorphous alloy powder has a composition formula Fe represented by the atomic ratio x Cu a Nb b (Si 1-y B y ) 100-x-a-b [a, b, x satisfy 0.3 ≦ a ≦ 2.0, 2.0 ≦ b ≦ 4.0, 72.5 ≦ x < 75.5. Also, y is a number that satisfies f(x) ≦ y ≦ 0.99, and f(x) = (4×10 -34 )x 17.56 .] It is a powder of an amorphous alloy composed of the composition and impurities as described above. The average particle diameter of the amorphous alloy powder is 10.0 μm or more and 45.0 μm or less.

[0078] Such amorphous alloy powder may have stress strain during the manufacturing process or the like. Therefore, by subjecting the amorphous alloy powder to heat treatment described later, the stress strain is relaxed and the amorphous alloy powder is crystallized.

[0079] The crystallinity of each particle of the amorphous alloy powder is less than 50%, preferably 30% or less. The crystallinity is obtained by acquiring an X-ray diffraction spectrum for the amorphous alloy powder and calculated based on the following formula. Crystallinity = {Intensity derived from crystal / (Intensity derived from crystal + Intensity derived from amorphous)} × 100

[0080] The amorphous alloy powder may be manufactured by any manufacturing method. For example, it is manufactured by various powdering methods such as an atomization method such as a water atomization method, a gas atomization method, a rotating water flow atomization method, a reduction method, a carbonyl method, and a pulverization method.

[0081] The atomization method is a method for producing powder by atomizing and cooling molten raw materials by colliding them with a fluid such as a liquid or gas injected at high speed. Depending on the type of cooling medium and the configuration of the apparatus, the atomization method includes the water atomization method, the gas atomization method, the rotating water flow atomization method, and the like. Among these, the amorphous alloy powder is preferably produced by the water atomization method or the rotating water flow atomization method, and more preferably produced by the rotating water flow atomization method.

[0082] In addition, the "water atomization method" in this specification refers to a method for producing metal powder by using a liquid such as water or oil as a coolant, injecting it in an inverted conical shape that converges at one point, and flowing and colliding molten metal toward this convergence point.

[0083] Also, the "rotating water flow atomization method" in this specification is a method in which a coolant is ejected and supplied along the inner peripheral surface of a cooling cylinder and rotated to form a coolant layer on the inner peripheral surface, and a molten metal obtained by melting the raw material of the amorphous alloy powder is scattered and brought into contact with this coolant layer. The atomized molten metal is taken into the coolant layer and rapidly cooled and solidified. Thereby, amorphous alloy powder is obtained.

[0084] In the rotating water flow atomization method, by continuously supplying the coolant, an extremely high cooling rate can be stably maintained, so that the amorphization of the produced amorphous alloy powder is promoted.

[0085] The amorphous alloy powder may be subjected to a classification process as necessary. Examples of the classification method include dry classification such as sieving classification, inertial classification, centrifugal classification, and pneumatic classification, and wet classification such as sedimentation classification.

[0086] 2.2. Heat treatment process In the heat treatment step S104, the amorphous alloy powder is heat-treated at a temperature of 500°C or higher and 600°C or lower. Thereby, the stress strain possessed by the amorphous alloy powder can be relaxed, and a soft magnetic alloy powder having a low coercive force can be obtained. Further, the amorphous alloy powder is crystallized, and a soft magnetic alloy powder containing crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less is obtained.

[0087] The volume resistivity of the compacted powder produced using this soft magnetic alloy powder is 10.0×10 -3 [Ω·cm] or less. Thereby, variations in the coercive force of the produced soft magnetic alloy powder can be suppressed. The reason for obtaining such an effect is considered to be that when the volume resistivity is within the above range, the stress strain is likely to be relaxed in the atomic arrangement and the like. That is, when the volume resistivity of the soft magnetic alloy powder is within the above range, even if the temperature, time, etc. in the heat treatment vary from particle to particle, it is considered that the progress of the heat treatment is hardly affected. For this reason, while achieving low coercive force for the entire soft magnetic alloy powder, it is possible to form crystal grains that are minute and have a uniform particle size. In addition, since particles that become defective due to insufficient or excessive heat treatment are less likely to occur, it is possible to efficiently produce a soft magnetic alloy powder that satisfies a predetermined coercive force and has stable quality.

[0088] Note that the volume resistivity of the compacted powder is considered to be related to the presence or absence of oxides on the particle surface. Therefore, suppressing the formation of oxides in the manufacturing process of the amorphous alloy powder and subsequent heat treatment is one method of reducing the volume resistivity.

[0089] The volume resistivity of the compacted powder is preferably 9.0×10 -3 [Ω·cm] or less, and more preferably 7.0×10 -3 [Ω·cm] or less. On the other hand, from the viewpoint of being able to be manufactured efficiently and stably, the lower limit value of the volume resistivity of the compacted powder is preferably 1.0×10 -3 [Ω·cm] or more, and more preferably 3.0×10 -3 [Ω·cm] or more.

[0090] The method for measuring the volume resistivity of the compressed powder is as follows. First, 7.0 g of soft magnetic alloy powder is placed as a sample in the sample container of the powder resistivity measurement probe unit. The inner radius of the sample container is set to 10.0 mm. Also, the radius of the electrode provided in the sample container is 0.7 mm, the electrode interval is 3.0 mm, and the probe is a four-probe type. Next, the sample is gradually pressurized by the hydraulic pump attached to the unit to prepare a compressed powder in the shape of a column with a mass of 7.0 g. With a pressure of 63.7 MPa applied to the compressed powder, the volume resistivity of the compressed powder is measured by the resistivity meter connected to the unit. Note that for the powder resistivity measurement probe unit, a powder resistivity measurement system manufactured by Nitto Seiko Analytic Co., Ltd. is used. Also, for the resistivity meter, a low resistivity meter Loresta-GP manufactured by Nitto Seiko Analytic Co., Ltd. is used.

[0091] The heat treatment temperature is set to 500°C or higher and 600°C or lower, preferably 520°C or higher and 590°C or lower, and more preferably 540°C or higher and 580°C or lower. If the heat treatment temperature is within the above range, the amorphous alloy powder can be appropriately crystallized while sufficiently relaxing the stress strain.

[0092] Note that if the heat treatment temperature is below the lower limit value, the stress strain cannot be sufficiently relaxed, and the coercive force increases. Also, the crystallization becomes insufficient. On the other hand, if the heat treatment temperature exceeds the upper limit value, the crystallization progresses excessively and the crystal grains become large.

[0093] The time for maintaining the above temperature in the heat treatment (heat treatment time) is preferably 5 minutes or more and 60 minutes or less, more preferably 7 minutes or more and 45 minutes or less, and even more preferably 10 minutes or more and 30 minutes or less. If the heat treatment time is within the above range, the amorphous alloy powder can be appropriately crystallized while sufficiently relaxing the stress strain.

[0094] In addition, if the heat treatment time is less than the lower limit value, stress strain cannot be sufficiently relaxed, and the coercive force may increase. On the other hand, if the heat treatment time exceeds the upper limit value, no further effect can be expected, and the energy efficiency of the heat treatment may decrease. In addition, there is a risk that crystallization may proceed excessively.

[0095] The heat treatment is performed using, for example, a heat treatment furnace. The pressure inside the heat treatment furnace may be atmospheric pressure, negative pressure, or positive pressure. Among these, a positive pressure is preferable. By performing the heat treatment with a positive pressure inside the heat treatment furnace, the thermal conductivity around the amorphous alloy powder inside the heat treatment furnace can be increased. As a result, the amorphous alloy powder can be heated evenly to every corner, and further reduction of the coercive force of the soft magnetic alloy powder as a whole can be achieved.

[0096] The pressure inside the heat treatment furnace is preferably a positive pressure of 5 Pa or more and 1000 Pa or less, more preferably a positive pressure of 10 Pa or more and 700 Pa or less, and even more preferably a positive pressure of 30 Pa or more and 500 Pa or less. If the pressure inside the heat treatment furnace is within the above range, further reduction of the coercive force of the soft magnetic alloy powder as a whole can be achieved. In particular, between the particles of the amorphous alloy powder, gas exists in a narrow space, and it mediates heat conduction while being affected by the interparticle distance. Therefore, it is considered that the thermal conductivity between particles is easily affected by pressure.

[0097] In addition, if the pressure inside the heat treatment furnace is less than the lower limit value, the temperature and the like in the heat treatment are likely to vary for each particle, and there is a risk that heat treatment deficiencies or excesses may occur in some parts. On the other hand, if the pressure inside the heat treatment furnace exceeds the upper limit value, no further effect can be expected, and the energy efficiency of the heat treatment may decrease.

[0098] Note that, for example, a positive pressure of 10 Pa is a pressure 10 Pa higher than atmospheric pressure. For example, when the atmospheric pressure is 101.3 kPa, it refers to 101.31 kPa.

[0099] The atmosphere inside the heat treatment furnace is not particularly limited and may be, for example, an acidic atmosphere, a reducing atmosphere, etc., but an inert atmosphere is preferred. An inert atmosphere with an oxygen volume concentration of 1500 ppm or less is more preferred, an inert atmosphere with an oxygen volume concentration of 200 ppm or more and 1000 ppm or less is even more preferred, and an inert atmosphere with an oxygen volume concentration of 300 ppm or more and 700 ppm or less is particularly preferred. If the oxygen volume concentration of the inert atmosphere is within the above range, oxidation of the amorphous alloy powder can be more reliably suppressed. Therefore, formation of an oxide film on the surface of the particles can be suppressed, and an increase in the volume resistivity of the above-described compact can be suppressed. Further, when an oxide film is formed, there is a possibility that stress strain is less likely to be relaxed. Taking this into account, if the oxygen volume concentration is within the above range, the coercive force of the amorphous alloy powder can be favorably reduced by heat treatment.

[0100] Examples of the inert gas constituting the inert atmosphere include nitrogen gas, argon gas, and the like.

[0101] 3. Compressed Powder Core and Magnetic Element Next, the compressed powder core and magnetic element according to the embodiment will be described.

[0102] The magnetic element according to the embodiment is applicable to various magnetic elements having a core, such as a choke coil, an inductor, a noise filter, a reactor, a transformer, a motor, an actuator, a solenoid valve, a generator, and the like. Further, the compressed powder core according to the embodiment is applicable to the core provided in these magnetic elements.

[0103] Hereinafter, as an example of the magnetic element, two types of coil components will be described as representatives. 3.1. Toroidal Type First, the toroidal type coil component, which is a magnetic element according to the embodiment, will be described.

[0104] FIG. 3 is a plan view schematically showing a toroidal type coil component. The coil component 10 shown in FIG. 3 includes a ring-shaped compacted powder core 11 and a conductive wire 12 wound around the compacted powder core 11.

[0105] The compacted powder core 11 is obtained by mixing the above-described soft magnetic alloy powder and a binder, and supplying the resulting mixture to a mold, followed by pressurization and molding. That is, the compacted powder core 11 is a compacted body containing the soft magnetic alloy powder according to the embodiment. Such a compacted powder core 11 has a low coercive force and a low iron loss.

[0106] Further, the coil component 10 includes such a compacted powder core 11. Such a coil component 10 has a low iron loss and contributes to power saving of electronic devices.

[0107] Examples of the constituent materials of the binder used for manufacturing the compacted powder core 11 include organic materials such as silicone resins, epoxy resins, phenolic resins, polyamide resins, polyimide resins, polyphenylene sulfide resins, etc., phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, cadmium phosphate, and inorganic materials such as silicates such as sodium silicate.

[0108] Examples of the constituent materials of the conductive wire 12 include materials with high conductivity, such as metal materials containing Cu, Al, Ag, Au, Ni, etc. Further, an insulating film is provided on the surface of the conductive wire 12 as necessary.

[0109] Note that the shape of the compacted powder core 11 is not limited to the ring shape shown in FIG. 3, and may be, for example, a shape in which a part of the ring is missing, or a shape in which the longitudinal shape is linear.

[0110] Further, the compacted powder core 11 may contain, as necessary, soft magnetic powders or non-magnetic powders other than the soft magnetic alloy powder according to the above-described embodiment.

[0111] 3.2. Closed magnetic circuit type Next, a closed magnetic circuit type coil component, which is a magnetic element according to the embodiment, will be described. FIG. 4 is a perspective view showing schematically a closed magnetic circuit type coil component.

[0112] Hereinafter, the closed magnetic circuit type coil component will be described. In the following description, the differences from the toroidal type coil component will be mainly described, and the description of the same matters will be omitted.

[0113] The coil component 20 shown in FIG. 4 includes a chip-shaped compacted powder core 21 and a conductor wire 22 embedded inside the compacted powder core 21 and formed in a coil shape. That is, the compacted powder core 21 is a compacted body containing the soft magnetic alloy powder according to the embodiment. Such a compacted powder core 21 has a low coercive force and a low iron loss.

[0114] Further, the coil component 20 includes such a compacted powder core 21. Such a coil component 20 has a low iron loss and contributes to power saving of electronic devices.

[0115] Note that the compacted powder core 21 may contain soft magnetic powders or non-magnetic powders other than the soft magnetic alloy powder according to the above-described embodiment, if necessary.

[0116] 4. Electronic Devices Next, an electronic device including the magnetic element according to the embodiment will be described with reference to FIGS. 5 to 7.

[0117] FIG. 5 is a perspective view showing a mobile personal computer which is an electronic device including the magnetic element according to the embodiment. The personal computer 1100 shown in FIG. 5 includes a main body portion 1104 having a keyboard 1102 and a display unit 1106 having a display portion 100. The display unit 1106 is rotatably supported with respect to the main body portion 1104 via a hinge structure portion. Such a personal computer 1100 incorporates magnetic elements 1000 such as a choke coil, an inductor, and a motor for a switching power supply.

[0118] FIG. 6 is a plan view showing a smartphone, which is an electronic device including a magnetic element according to an embodiment. The smartphone 1200 shown in FIG. 6 includes a plurality of operation buttons 1202, a receiver 1204, and a transmitter 1206. Further, a display unit 100 is disposed between the operation button 1202 and the receiver 1204. Such a smartphone 1200 incorporates a magnetic element 1000 such as an inductor, a noise filter, a motor, etc.

[0119] FIG. 7 is a perspective view showing a digital still camera, which is an electronic device including a magnetic element according to an embodiment. The digital still camera 1300 photoelectrically converts the optical image of a subject by an image sensor such as a CCD (Charge Coupled Device) to generate an imaging signal.

[0120] The digital still camera 1300 shown in FIG. 7 includes a display unit 100 provided on the back surface of a case 1302. The display unit 100 functions as a viewfinder for displaying the subject as an electronic image. Further, on the front side of the case 1302, that is, on the back side in the drawing, a light receiving unit 1304 including an optical lens, a CCD, etc. is provided.

[0121] When the photographer confirms the subject image displayed on the display unit 100 and presses the shutter button 1306, the imaging signal of the CCD at that time is transferred and stored in the memory 1308. Such a digital still camera 1300 also incorporates a magnetic element 1000 such as an inductor, a noise filter, etc.

[0122] In addition, as the electronic device according to the embodiment, in addition to the personal computer in FIG. 5, the smartphone in FIG. 6, and the digital still camera in FIG. 7, for example, mobile phones, tablet terminals, watches, inkjet ejection devices such as inkjet printers, laptop personal computers, televisions, video cameras, video tape recorders, car navigation devices, pagers, electronic notebooks, electronic dictionaries, calculators, electronic game devices, word processors, workstations, videophones, security television monitors, electronic binoculars, POS terminals, electronic thermometers, sphygmomanometers, glucometers, electrocardiogram measuring devices, ultrasonic diagnostic devices, medical devices such as electronic endoscopes, fish finders, various measuring devices, vehicles, aircraft, ship instruments, mobile control devices such as automotive control devices, aircraft control devices, railway vehicle control devices, and ship control devices, flight simulators, etc. can be mentioned.

[0123] Such an electronic device is provided with the magnetic element according to the embodiment. Thereby, the effect of the magnetic element of low iron loss can be enjoyed, and power saving of the electronic device can be achieved.

[0124] 5. Effects Exhibited by the Embodiment As described above, the method for manufacturing the soft magnetic alloy powder according to the embodiment has a composition formula Fe represented by the atomic ratio x Cu a Nb b (Si 1-y B y ) 100-x-a-b [a, b, x satisfy 0.3 ≦ a ≦ 2.0, 2.0 ≦ b ≦ 4.0, 72.5 ≦ x < 75.5. Also, y is a number that satisfies f(x) ≦ y ≦ 0.99, and f(x) = (4 × 10 -34 )x 17.56A powder production step S102 for producing an amorphous alloy powder composed of the composition and impurities thereof, having an average particle size of 10.0 μm or more and 45.0 μm or less, and a heat treatment step S104 for crystallizing the amorphous alloy powder by performing heat treatment on the amorphous alloy powder at a temperature of 500 °C or more and 600 °C or less to produce a soft magnetic alloy powder containing 30% by volume or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less. And when the soft magnetic alloy powder is pressed at a pressure of 63.7 MPa to produce a green compact having a mass of 7.0 g, the volume resistivity of the green compact is 10.0×10 -3 [Ω·cm] or less.

[0125] According to such a configuration, the stress strain of the amorphous alloy powder can be sufficiently relaxed, and a soft magnetic alloy powder having a low coercive force can be produced. Further, a soft magnetic alloy powder with less variation in coercive force and stable quality can be obtained.

[0126] In the method for producing a soft magnetic alloy powder according to the above embodiment, the heat treatment time is 5 minutes or more and 60 minutes or less.

[0127] According to such a configuration, the amorphous alloy powder can be appropriately crystallized and the stress strain can be sufficiently relaxed.

[0128] In the method for producing a soft magnetic alloy powder according to the above embodiment, the coercive force of the soft magnetic alloy powder is 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less.

[0129] According to such a configuration, a soft magnetic alloy powder capable of manufacturing a powder core having a particularly low coercive force and sufficiently suppressing hysteresis loss can be obtained.

[0130] Further, in the method for producing a soft magnetic alloy powder according to the above embodiment, the heat treatment is performed under a positive pressure of 5 Pa or more and 1000 Pa or less.

[0131] According to such a configuration, further low coercivity magnetization can be achieved for the entire soft magnetic alloy powder. Also, during the heat treatment, gas exists in the narrow spaces between the amorphous alloy powder particles, and since it mediates heat conduction while being affected by the inter-particle distance, the thermal conductivity between the particles is considered to be easily affected by pressure. Therefore, by performing the heat treatment under the above pressure, the temperature variation during the heat treatment can be suppressed.

[0132] Moreover, in the method for manufacturing the soft magnetic alloy powder according to the above embodiment, the heat treatment is performed in an inert atmosphere with an oxygen volume concentration of 1500 ppm or less.

[0133] According to such a configuration, oxidation of the amorphous alloy powder can be more reliably suppressed. Also, since the formation of an oxide film on the surface of the particles can be suppressed, it is possible to suppress the difficulty of relaxing stress strain.

[0134] Moreover, the soft magnetic alloy powder according to the above embodiment has a composition formula Fe x Cu a Nb b (Si 1-y B y ) 100-x-a-b [a, b, x are numbers with units of atomic %, respectively, satisfying 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 72.5 ≤ x < 75.5. Also, y is a number satisfying f(x) ≤ y ≤ 0.99, where f(x) = (4×10 -34 )x 17.56 .] composed of the composition and impurities, having an average particle size of 10.0 μm or more and 45.0 μm or less, containing 30% by volume or more of crystal grains with a crystal grain size of 1.0 nm or more and 30.0 nm or less, and when a compacted body with a mass of 7.0 g is produced by being pressed at a pressure of 63.7 MPa, the volume resistivity of the compacted body is 10.0×10 -3 [Ω·cm] or less.

[0135] According to such a configuration, a soft magnetic alloy powder with a low coercivity and little variation in coercivity can be obtained.

[0136] In addition, the soft magnetic alloy powder according to the embodiment has a coercive force of 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less.

[0137] According to such a configuration, a soft magnetic alloy powder capable of manufacturing a compacted powder core capable of sufficiently suppressing hysteresis loss can be obtained.

[0138] In addition, the compacted powder core according to the embodiment contains the soft magnetic alloy powder according to the embodiment. According to such a configuration, a compacted powder core having a low coercive force and a low iron loss can be obtained.

[0139] In addition, the magnetic element according to the embodiment includes the compacted powder core according to the embodiment. According to such a configuration, it has a low iron loss and can contribute to power saving of electronic devices.

[0140] In addition, the electronic device according to the embodiment includes the magnetic element according to the embodiment. According to such a configuration, the effect of the magnetic element of low iron loss can be enjoyed, and power saving of the electronic device can be achieved.

[0141] As described above, the manufacturing method, soft magnetic alloy powder, compacted powder core, magnetic element, and electronic device of the present invention have been described based on preferred embodiments, but the present invention is not limited thereto. For example, the compacted powder core and magnetic element according to the present invention may be those in which each part of the embodiment is replaced with any component having the same function, or those in which any component is added to the embodiment.

[0142] In addition, in the above embodiment, a compacted powder core has been described as an example of the use of the soft magnetic alloy powder of the present invention, but the use example is not limited thereto, and for example, it may be a magnetic device such as a magnetic fluid, a magnetic shielding sheet, or a magnetic head. Also, the shapes of the compacted powder core and the magnetic element are not limited to those shown, and may be any shape.

[0143] Furthermore, the method for producing the soft magnetic alloy powder of the present invention may include any step added for any purpose to the above-described embodiment. EXAMPLES

[0144] Next, specific examples of the present invention will be described. 6. Manufacturing of powder magnetic cores 6.1. Samples No. 1 to 14 First, the raw materials were melted in a high-frequency induction furnace and pulverized by a rotating water jet atomization method to obtain an amorphous alloy powder.

[0145] Next, the obtained amorphous alloy powder was subjected to a heat treatment under the conditions shown in Table 1. As a result, a soft magnetic alloy powder was obtained.

[0146] Next, classification was performed using a classifier using a mesh. The alloy composition of the classified soft magnetic alloy powder is shown in Table 1. The values of x and y obtained from the alloy composition are plotted on the graph shown in Figure 1, and when the alloy composition is included in any of regions A to C, the symbol is shown in Table 1.

[0147] Next, the classified soft magnetic alloy powder was mixed with an epoxy resin as a binder and toluene as an organic solvent to obtain a mixture. The amount of the epoxy resin added was 2 parts by mass with respect to 100 parts by mass of the soft magnetic alloy powder.

[0148] Next, the mixture was stirred and then dried for a short time to obtain a lump-shaped dried body. The dried body was then sieved through a sieve with a mesh size of 400 μm, and the dried body was pulverized to obtain a granulated powder. The obtained granulated powder was dried at 50° C. for 1 hour.

[0149] Next, the obtained granulated powder was filled into a molding die, and a molded body was obtained based on the following molding conditions.

[0150] <Molding conditions> Molding method: Press molding Shape of molded body: Ring-shaped · Dimensions of the compact: outer diameter 14 mm, inner diameter 8 mm, thickness 3 mm · Compaction pressure: 0.5 t / cm 2 (49 MPa) · Compaction temperature: 70 °C

[0151] Next, the compact was heated at a temperature of 150 °C for 0.50 hours in an air atmosphere to cure the binder. Thereby, a powder compact magnetic core was obtained.

[0152] The average particle diameter, the content ratio of crystal grains, and the volume resistivity of the powder compact of the soft magnetic alloy powder used for manufacturing the powder compact magnetic core are shown in Table 2. For the measurement of the average particle diameter, Microtrac, HRA9320-X100, manufactured by Nikkiso Co., Ltd., a particle size distribution measuring device by the laser diffraction method, was used.

[0153] 6.2. Sample Nos. 15 to 33 A powder compact magnetic core was obtained in the same manner as in the case of Sample Nos. 1 to 14, except that a soft magnetic alloy powder manufactured under the manufacturing conditions shown in Table 3 and having an average particle diameter, a content ratio of crystal grains, and a volume resistivity of the powder compact as shown in Table 4 was used.

[0154] In Tables 1 to 4, among the soft magnetic alloy powders of each sample No., those corresponding to the present invention in the manufacturing method are indicated as "Examples", and those not corresponding to the present invention are indicated as "Comparative Examples".

[0155]

Table 1

[0156]

Table 2

[0157]

Table 3

[0158]

Table 4

[0159] 7. Evaluation of Soft Magnetic Alloy Powder 7.1 Coercive Force of Soft Magnetic Alloy Powder For the soft magnetic alloy powders obtained in each example and each comparative example, the coercive force was measured. The measurement results are shown in Tables 2 and 4.

[0160] 7.2 Variation in Coercive Force of Soft Magnetic Alloy Powder For the soft magnetic alloy powders obtained in each example and each comparative example, the variation in coercive force was evaluated by the following method. The evaluation results are shown in Tables 2 and 4.

[0161] First, 50 g of the soft magnetic alloy powder was prepared and divided into 10 equal parts. Then, for each of the divided parts, the coercive force was measured, and the range of the measured values (the difference between the maximum value and the minimum value) was evaluated according to the following evaluation criteria.

[0162] A: The range of the measured values is particularly small B: The range of the measured values is slightly large, but there is little practical problem C: The range of the measured values is large, and there are some practical problems D: The range of the measured values is particularly large, and there are many practical problems

[0163] 7.3 Permeability of Magnetic Element Using the compacted magnetic cores obtained in each example and each comparative example, magnetic elements were fabricated based on the following fabrication conditions.

[0164] · Constituent material of the wire: Cu · Wire diameter of the wire: 0.6 mm · Number of turns: 7 turns

[0165] Next, for the fabricated magnetic elements, the permeability was measured based on the following measurement conditions. · Measuring device: Impedance Analyzer 4294A manufactured by Keysight Technologies Co., Ltd. · Measuring frequency: 1 MHz

[0166] Then, the obtained magnetic permeability was evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 4.

[0167] A: The magnetic permeability is 24.5 or more B: The magnetic permeability is 23.0 or more and less than 24.5 C: The magnetic permeability is less than 23.0

[0168] 7.4. Iron loss of the magnetic element Using the compacted magnetic cores obtained in each example and each comparative example, magnetic elements were produced based on the following production conditions.

[0169] · Constituent material of the wire: Cu · Wire diameter of the wire: 0.16 mm · Number of turns: 18 turns on the primary side and 18 turns on the secondary side

[0170] Next, for the produced magnetic elements, the iron loss was measured based on the following measurement conditions. The measurement results are shown in Tables 2 and 4.

[0171] · Measuring device: BH Analyzer SY-8218 manufactured by Iwasaki Telecommunications Co., Ltd. · Measuring frequency: 1 MHz · Maximum magnetic flux density: 20 mT

[0172] As shown in Tables 2 and 4, it was confirmed that the soft magnetic alloy powders obtained in each example had a lower coercive force than the soft magnetic alloy powders obtained in each comparative example. Also, the variation in the coercive force was suppressed to a small extent.

[0173] Furthermore, it was confirmed that the soft magnetic alloy powders obtained in each example had good magnetic permeability and low iron loss.

Explanation of symbols

[0174] 10... Coil component, 11... Powdered iron core, 12... Conductive wire, 20... Coil component, 21... Powdered iron core, 22... Conductive wire, 100... Display unit, 1000... Magnetic element, 1100... Personal computer, 1102... Keyboard, 1104... Main body, 1106... Display unit, 1200... Smartphone, 1202... Operation button, 1204... Earphone jack, 1206... Microphone jack, 1300... Digital still camera, 1302... Case, 1304... Light receiving unit, 1306... Shutter button, 1308... Memory, A... Area, B... Area, C... Area, S102... Powder manufacturing process, S104... Heat treatment process

Claims

1. The composition formula Fe expressed in terms of atomic ratio ｘ Cu ａ Nb ｂ (Si １－ｙ B ｙ ) １００－ｘ－ａ－ｂ [a, b, and x are such that 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 72.5 ≤ x < 75.5 are satisfied. Also, y is a number that satisfies f(x) ≤ y ≤ 0.99, where f(x) = (4 × 10 －３４ )x １７．５６ .] A powder manufacturing process for producing an amorphous alloy powder composed of the composition and impurities, having an average particle size of 10.0 μm or more and 45.0 μm or less, and a heat treatment process for crystallizing the amorphous alloy powder by performing a heat treatment on the amorphous alloy powder at a temperature of 500°C or more and 600°C or less to produce a soft magnetic alloy powder containing 30% by volume or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less. It has When the soft magnetic alloy powder is pressed at a pressure of 63.7 MPa to produce a green compact with a mass of 7.0 g, the volume resistivity of the green compact is 10.0×10 －３ [Ω·cm] or less, and a method for producing a soft magnetic alloy powder is characterized by this.

2. The method for producing a soft magnetic alloy powder according to claim 1, wherein the time of the heat treatment is 5 minutes or more and 60 minutes or less.

3. The method for producing a soft magnetic alloy powder according to claim 1 or 2, wherein the coercive force of the soft magnetic alloy powder is 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less.

4. The method for producing a soft magnetic alloy powder according to claim 1 or 2, wherein the heat treatment is performed under a pressure of 5 Pa or more and 1000 Pa or less of positive pressure.

5. The method for producing a soft magnetic alloy powder according to claim 1 or 2, wherein the heat treatment is performed in an inert atmosphere with an oxygen volume concentration of 1500 ppm or less.

6. The composition formula Fe expressed in terms of atomic ratio ｘ Cu ａ Nb ｂ (Si １－ｙ B ｙ ) １００－ｘ－ａ－ｂ [a, b, and x are each a number with the unit of atomic %, and 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 72.5 ≤ x < 75.5 are satisfied. Also, y is a number that satisfies f(x) ≤ y ≤ 0.99, where f(x) = (4×10 －３４ )x １７．５６ . Composed of the composition and impurities, having an average particle size of 10.0 μm or more and 45.0 μm or less, containing 30% by volume or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less, When a compacted powder with a mass of 7.0 g is produced under a pressure of 63.7 MPa, the volume resistivity of the compacted powder is 10.0×10 －３ [Ω·cm] or less, and the soft magnetic alloy powder is characterized by this.

7. The soft magnetic alloy powder according to claim 6, having a coercive force of 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less.

8. A compacted powder core characterized by containing the soft magnetic alloy powder according to claim 6 or 7.

9. A magnetic element characterized by including the compacted powder core according to claim 8.

10. An electronic device characterized by including the magnetic element according to claim 9.

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