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-y(B1-zCrz)y)100-x-a-b [0.3≤a≤2.0, 2.0≤b≤4.0, 75.5≤x≤79.5, 0.55≤y≤0.91, and 0.015≤z≤0.185 are satisfied]; and a step of heating at a temperature of 420°C or higher and 620°C or lower to produce a soft magnetic alloy powder, wherein a crystal grain size as measured by X-ray diffraction is 5.0 nm or more and 20.0 nm or less, and the volume resistivity of a green compact is 9.0×10-3 [Ω cm] or less.SELECTED DRAWING: Figure 1

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, satisfying 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 performing heat treatment 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 manufacturing 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, it is an issue to improve the manufacturing method so that the coercivity can be more reliably decreased without impairing the manufacturing efficiency of the soft magnetic powder.

Means for Solving the Problems

[0006] The method for manufacturing 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 1-z Cr z ) y ) 100-x-a-b [where a, b, x, y, and z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.185.] a powder manufacturing step of manufacturing an amorphous alloy powder composed of the composition and impurities described above, having an average particle size 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 420°C or higher and 620°C or lower to manufacture a soft magnetic alloy powder, and having a crystal grain size of the soft magnetic alloy powder measured by an X-ray diffraction method of 5.0 nm or more and 20.0 nm or less, 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 9.0×10 -3 [Ω·cm] or less.

[0007] ​The soft magnetic alloy powder according to the application example of the present invention is The composition formula Fe represented by the atomic ratio x Cu a Nb b (Si 1-y (B 1-z Cr z ) y ) 100-x-a-b [a, b, x, y, z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.185, .] Composed of the composition and impurities of The average particle size is 10.0 μm or more and 45.0 μm or less, The crystal grain size measured by the X-ray diffraction method is 5.0 nm or more and 20.0 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 9.0×10 -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 Is provided with 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 Is provided with the magnetic element according to the application example of the present invention.

Brief Description of the Drawings

[0011]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a method for producing a soft magnetic alloy powder, a soft magnetic alloy powder, a compacted magnetic core, a magnetic element, and an electronic device according to 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, for example, it is used for the production of a compacted magnetic core. The compacted magnetic core is produced 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 expressed in atomic ratio x Cu a Nb b (Si 1-y (B 1-z Cr z ) y ) 100-x-a-b and impurities. a, b, x, y, z satisfy 0.3 ≦ a ≦ 2.0, 2.0 ≦ b ≦ 4.0, 75.5 ≦ x ≦ 79.5, 0.55 ≦ y ≦ 0.91, 0.015 ≦ z ≦ 0.185.

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

[0017] Furthermore, the soft magnetic alloy powder according to the embodiment has a crystal grain size measured by the X-ray diffraction method of 5.0 nm or more and 20.0 nm or less. These crystal grains are formed by performing heat treatment on the amorphous alloy powder, which is a precursor, 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 green compact with a mass of 7.0 g, the volume resistivity of the green compact is 9.0×10 -3 [Ω·cm] or less.

[0019] By configuring the volume resistivity of the green compact 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 green compact 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 green compact is within the above range has homogeneity that can suppress the variation in each measured value to a small extent when, for example, it is divided into a plurality of particle groups and the coercive force is measured for each. In other words, it can be said that such a soft magnetic alloy powder stably enjoys the effect of heat treatment in each particle and is a powder in which low coercive force is achieved. Therefore, by manufacturing products such as powder cores using such a soft magnetic alloy powder, products with stable characteristics can be manufactured with few individual differences.

[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 1-z Cr z ) y ) 100-x-a-b This composition formula represents the ratio in terms of the number of atoms in the composition consisting of the six elements Fe, Cu, Nb, Si, B, and Cr.

[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 rate x of Fe is set to be 75.5 atomic % or more and 79.5 atomic % or less, preferably 76.0 atomic % or more and 78.5 atomic % or less, and more preferably 76.5 atomic % or more and 78.0 atomic % or less. If the content rate 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 rate x of Fe exceeds the upper limit value, an amorphous structure cannot be stably formed during the production of the soft magnetic alloy powder, so the crystal grain size becomes too large, which may lead to an increase in the coercive force.

[0023] Cu (copper) tends to be separated from Fe when the soft magnetic alloy powder according to the embodiment is produced from raw materials. For this reason, when Cu is contained, the composition fluctuates, 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 a crystal phase having the crystal grain size as described above is likely to be formed.

[0024] The content rate 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. If the content rate a of Cu is less than the lower limit value, the refinement of the crystal phase may be impaired. On the other hand, if the content rate a of Cu exceeds the upper limit value, the mechanical properties of the soft magnetic alloy powder may deteriorate and it may become brittle.

[0025] Nb (niobium) contributes to the refinement of crystal grains together with Cu when the amorphous alloy powder is subjected to heat treatment. For this reason, crystal grains having the crystal grain size as described above are likely to be formed.

[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. If the content ratio b of Nb is less than the lower limit value, the refinement of crystal grains may be impaired. On the other hand, if the content ratio b of Nb exceeds the upper limit value, the mechanical properties of the soft magnetic alloy powder may deteriorate and it may 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 crystal grain size. The uniform crystal grain 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 crystal grain size. As a result, the coercive force can be reduced and the magnetic permeability can be increased, and the improvement of soft magnetism can be achieved. Also, by using Si and B in combination, based on the difference in atomic radius between the two, the amorphization can be synergistically promoted.

[0029] Cr (chromium) suppresses the coarsening of crystal grains and aims to make the crystal grain size uniform. Thereby, the reduction of the coercive force of the soft magnetic alloy powder can be achieved. Also, Cr increases the oxidation resistance of the soft magnetic alloy powder. As a result, when the soft magnetic alloy powder is compacted, it is possible to suppress the decrease in the density of the compact due to oxides. As a result, the magnetic permeability and saturation magnetic flux density measured in the state of the compact can be increased.

[0030] Here, the total content ratio of Si, B, and Cr (Si + B + Cr) is set to 1, and the ratio of the total content ratio of B and Cr (B + Cr) to this total content ratio (Si + B + Cr) is defined as y.

[0031] This y satisfies 0.55 ≤ y ≤ 0.91, preferably satisfies 0.60 ≤ y ≤ 0.90, and more preferably satisfies 0.65 ≤ y ≤ 0.80. Thereby, the quantitative balance among Si, B, and Cr can be achieved. As a result, both the oxidation resistance and the magnetic permeability of the soft magnetic alloy powder can be enhanced well in balance.

[0032] When y is less than the lower limit value, the oxidation resistance decreases, and the crystal grain size becomes too small, resulting in a decrease in magnetic permeability. On the other hand, when y exceeds the upper limit value, the crystal grain size becomes too large, leading to an increase in coercive force.

[0033] Also, the ratio of the content ratio of Cr to the total content ratio (B + Cr) is defined as z. This z satisfies 0.015 ≤ z ≤ 0.185, preferably satisfies 0.030 ≤ z ≤ 0.150, and more preferably satisfies 0.045 ≤ z ≤ 0.120. Thereby, the quantitative balance between B and Cr can be achieved. As a result, both the oxidation resistance and the magnetic permeability of the soft magnetic alloy powder can be enhanced well in balance.

[0034] When z is less than the lower limit value, the oxidation resistance decreases, and the crystal grain size becomes too small, resulting in a decrease in magnetic permeability. On the other hand, when z exceeds the upper limit value, the crystal grain size becomes too large, leading to an increase in coercive force.

[0035] Note that the content ratio of Si is preferably 1.5 atomic% or more and 14.0 atomic% or less, more preferably 3.0 atomic% or more and 10.0 atomic% or less, and still more preferably 4.0 atomic% or more and 8.0 atomic% or less. Thereby, the magnetic permeability of the soft magnetic alloy powder can be further enhanced, and the coercive force can be further decreased.

[0036] Further, the content rate of B is preferably 5.0 atomic % or more and 17.0 atomic % or less, more preferably 7.0 atomic % or more and 16.0 atomic % or less, and still more preferably 9.0 atomic % or more and 13.5 atomic % or less. Thereby, the magnetic permeability of the soft magnetic alloy powder can be further increased, and the coercive force can be further decreased.

[0037] Further, the content rate of Cr is preferably 0.3 atomic % or more and 2.7 atomic % or less, more preferably 0.5 atomic % or more and 2.2 atomic % or less, and still more preferably 0.8 atomic % or more and 1.8 atomic % or less. Thereby, the oxidation resistance of the soft magnetic alloy powder can be further increased, and the generation of oxides can be further suppressed. As a result, the decrease in the density of the green compact due to the oxides can be suppressed, and the magnetic permeability and saturation magnetic flux density of the compact can be further increased. Further, the crystal grain size of the crystal grains contained in each particle can be appropriately controlled, and the balance between low coercive force and high magnetic permeability can be further optimized.

[0038] The soft magnetic alloy powder according to the embodiment has the above compositional formula Fe x Cu a Nb b (Si 1-y (B 1-z Cr z ) y ) 100-x-a-b In addition to the composition represented by the above formula, it may contain impurities. Examples of the impurities include all elements other than those described above, but the total content rate of the impurities is preferably 0.50 atomic % or less. If it is within this range, even if impurities are mixed, it is difficult to inhibit the above effects, and thus the inclusion is allowed.

[0039] Further, the content rate of each element contained in the impurities is preferably 0.05 atomic % or less for each. If it is within this range, it is difficult for the impurities to inhibit the above effects, and thus the inclusion is allowed.

[0040] Among the impurities, particularly, the oxygen content is preferably 1500 ppm or less, more preferably 800 ppm or less in terms of mass ratio. If the oxygen content is within the above range, the formation of oxides that cause a decrease in the density of the compacted powder can be particularly reduced.

[0041] As described above, the soft magnetic alloy powder according to the embodiment has been explained. The above composition and impurities are specified by the following analysis methods.

[0042] Examples of the analysis methods include atomic absorption spectrometry for iron and steel specified in JIS G 1257:2000, ICP emission spectrometry for iron and steel specified in JIS G 1258:2007, spark discharge emission spectrometry for iron and steel specified in JIS G 1253:2002, fluorescent X-ray analysis for iron and steel specified in JIS G 1256:1997, and gravimetric, titrimetric, and absorptiometric methods specified in JIS G 1211 to G 1237.

[0043] Specifically, a solid emission spectrometry apparatus, for example, SPECTRO LAB M9 manufactured by SPECTRO, QSN750 manufactured by OBLF, etc. are preferably used.

[0044] 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, can be mentioned.

[0045] In particular, when specifying N (nitrogen) and O (oxygen), the nitrogen quantification method for iron and steel specified in JIS G 1228:1997 and the general rule for oxygen quantification method of metallic materials specified in JIS Z 2613:2006 are also used. Specifically, an oxygen and nitrogen analyzer, TC-300 / EF-300 manufactured by LECO, an oxygen, nitrogen, and hydrogen analyzer, ONH836 manufactured by LECO, etc. can be mentioned.

[0046] 1.2. Crystal Grain Size The soft magnetic alloy powder according to the embodiment has a crystal grain size of 5.0 nm or more and 20.0 nm or less as measured by the X-ray diffraction method. If the crystal grain size is within such a range, since the crystal grain size of the soft magnetic alloy powder is optimized, the magnetic permeability of the soft magnetic alloy powder can be increased. Further, the crystal magnetic anisotropy in each crystal grain is easily averaged, and a soft magnetic alloy powder with low coercive force can be obtained. Furthermore, since the magnetic permeability becomes high, it becomes difficult to saturate even under a high current, so it is easy to increase the saturation magnetic flux density of the soft magnetic alloy powder.

[0047] Note that the crystal grain size in the soft magnetic alloy powder is preferably 7.0 nm or more and 15.0 nm or less, and more preferably 8.0 nm or more and 13.0 nm or less.

[0048] The measurement of the crystal grain size by the X-ray diffraction method is performed by obtaining the X-ray diffraction patterns for the soft magnetic alloy powder and the standard sample respectively, estimating the diffraction line width derived from Fe, and then calculating the crystal grain size by the Scherrer method. The X-ray diffraction pattern obtained for the standard sample is used to estimate the diffraction line width derived from the apparatus. The crystal grain size calculated from the soft magnetic alloy powder can be corrected by this diffraction line width.

[0049] Each particle constituting the soft magnetic alloy powder according to the embodiment contains crystal grains having the above-described crystal grain size, but may further contain an amorphous structure. By the coexistence of the crystal grains and the amorphous structure, the magnetostriction of the soft magnetic alloy powder can be made smaller. As a result, a soft magnetic alloy powder having a particularly high magnetic permeability can be obtained. Further, a soft magnetic alloy powder whose magnetization can be easily controlled can be obtained.

[0050] 1.3. Various properties 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 the soft magnetic alloy powder having such an average particle size, the path through which eddy currents flow can be shortened, so that a powder compact core capable of sufficiently suppressing the eddy current loss generated in the particles can be manufactured.

[0051] In particular, when the average particle diameter of the soft magnetic alloy powder is equal to or greater than the lower limit value, by mixing with a soft magnetic alloy powder having a smaller average particle diameter than the soft magnetic alloy powder according to the embodiment, a high green compact density can be achieved.

[0052] The average particle diameter of the soft magnetic alloy powder is determined as the particle diameter D50 at which the cumulative value from the smaller diameter side reaches 50% in the volume-based particle size distribution obtained by the laser diffraction method.

[0053] When the average particle diameter of the soft magnetic alloy powder is less than the lower limit value, the soft magnetic alloy powder becomes too fine, so the fillability of the soft magnetic alloy powder may easily decrease. As a result, since the molding density of the compact magnetic core, which is an example of the green compact, decreases, the saturation magnetic flux density and magnetic permeability of the compact magnetic core may decrease. In addition, there is a risk of crystallization by heat treatment. On the other hand, when the average particle diameter of the soft magnetic alloy powder exceeds the upper limit value, the particle diameter becomes too large, so in the amorphous alloy powder, which is the precursor of the soft magnetic alloy powder, there is a risk that sufficient amorphization cannot be achieved. In addition, the relaxation of stress strain by heat treatment becomes insufficient, and low coercivity magnetization may become difficult.

[0054] For the soft magnetic alloy powder, in the volume-based particle size distribution obtained by the laser diffraction method, when the particle diameter at which the cumulative value from the smaller diameter side reaches 10% is defined as D10 and the particle diameter at which the cumulative value 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. Therefore, a green compact having particularly high magnetic properties such as magnetic permeability and saturation magnetic flux density can be obtained.

[0055] 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 such soft magnetic alloy powder with a small coercive force, a compacted powder core with sufficiently suppressed hysteresis loss can be manufactured.

[0056] 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 a low coercive force. Moreover, if the pursuit of the coercive force is excessive, 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 powder core increases.

[0057] 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.

[0058] The soft magnetic alloy powder according to the embodiment preferably has a magnetic permeability of 24.0 or more at a measurement frequency of 1 MHz when formed into a compacted body, and more preferably 25.0 or more. Such soft magnetic alloy powder has excellent DC superposition characteristics, high electromagnetic conversion efficiency under high frequencies, and contributes to the realization of miniaturized magnetic elements. In addition, this magnetic permeability is measured in a state where a conductor with a wire diameter of 0.6 mm is wound 7 times around a ring-shaped body with an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 3 mm after compacting the soft magnetic alloy powder together with an epoxy resin added at a ratio of 2% by mass to the soft magnetic alloy powder at a molding pressure of 294 MPa (3 t / cm 2 )). For the measurement of the magnetic permeability, for example, an impedance analyzer such as 4194A manufactured by Agilent Technologies, Inc. is used. Then, with the measurement frequency set to 1 MHz, the effective magnetic permeability obtained from the self-inductance of the closed magnetic circuit core coil is taken as the measured value.

[0059] The saturation magnetic flux density of the soft magnetic alloy powder according to the embodiment is preferably 1.25 [T] or more, and more preferably 1.30 [T] or more. Thereby, a magnetic element that is less likely to saturate even at a high current can be obtained.

[0060] The saturation magnetic flux density of the soft magnetic alloy powder is measured, for example, by the following method. First, the true specific gravity ρ of the soft magnetic alloy powder is measured using a fully automatic gas replacement type densitometer, AccuPyc1330 manufactured by Micromeritics Co., Ltd. Next, the maximum magnetization Mm of the soft magnetic alloy powder is measured using a vibrating sample magnetometer, VSM system TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd. Then, the saturation magnetic flux density Bs is calculated by the following formula. Bs = 4π / 10000 × ρ × Mm

[0061] The soft magnetic alloy powder according to the embodiment is mixed with 2% by mass of an epoxy resin, and the density of the compact obtained by press-molding the resulting mixture at a pressure of 294 MPa is 4.99 g / cm 3 or more, preferably 5.01 g / cm 3 or more and 5.20 g / cm 3 or less. If the density of the compact is within the above range, the occupancy rate of the oxide in the molded body can be sufficiently suppressed, and as a result, the occupancy rate of the alloy can be sufficiently ensured. Thereby, the magnetic permeability and saturation magnetic flux density of the magnetic element can be further increased.

[0062] Note that the soft magnetic alloy powder according to the embodiment may be mixed with other soft magnetic powders or non-soft magnetic powders and used as a mixed powder for various applications.

[0063] 2. Method for manufacturing soft magnetic alloy powder Next, a method for manufacturing the soft magnetic alloy powder according to the embodiment will be described. FIG. 1 is a process diagram showing the configuration of a method for manufacturing a soft magnetic alloy powder according to the embodiment. The method for manufacturing the soft magnetic alloy powder shown in FIG. 1 includes a powder manufacturing step S102 and a heat treatment step S104.

[0064] 2.1. Powder manufacturing process In the powder manufacturing process S102, powder (amorphous alloy powder) before heat treatment is manufactured.

[0065] The amorphous alloy powder has a composition formula Fe expressed in atomic ratio x Cu a Nb b (Si 1-y (B 1-z Cr z ) y ) 100-x-a-b [a, b, x, y, z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.185.] It is a powder of an amorphous alloy composed of the composition and impurities. Also, the average particle size of the amorphous alloy powder is 10.0 μm or more and 45.0 μm or less.

[0066] Such amorphous alloy powder may have stress strain in 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.

[0067] The amorphous alloy powder has a crystallinity of less than 50% in each particle, 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 = {crystal-derived intensity / (crystal-derived intensity + amorphous-derived intensity)} × 100

[0068] The amorphous alloy powder may be manufactured by any manufacturing method. For example, it is manufactured by various powdering methods such as atomization methods such as water atomization method, gas atomization method, and rotating water flow atomization method, reduction method, carbonyl method, and pulverization method.

[0069] The atomization method is a method of 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.

[0070] Note that the "water atomization method" in this specification refers to a method of 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.

[0071] In addition, the "rotating water flow atomization method" in this specification is a method of forming a coolant layer on the inner peripheral surface by ejecting and supplying a coolant along the inner peripheral surface of a cooling cylinder and swirling it, and scattering and bringing into contact with the coolant layer a molten metal obtained by melting the raw material of the amorphous alloy powder. The atomized molten metal is taken into the coolant layer and rapidly cooled and solidified. Thereby, amorphous alloy powder is obtained.

[0072] 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.

[0073] The amorphous alloy powder may be subjected to a classification treatment as necessary. Examples of the classification treatment method include dry classification such as sieving classification, inertial classification, centrifugal classification, and pneumatic classification, and wet classification such as sedimentation classification.

[0074] 2.2. Heat treatment process In the heat treatment step S104, the amorphous alloy powder is heat-treated at a temperature of 420°C or higher and 620°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 measured by the X-ray diffraction method of 5.0 nm or more and 20.0 nm or less is obtained.

[0075] The volume resistivity of the compacted powder produced using this soft magnetic alloy powder is 9.0×10 -3 [Ω·cm] or less. Thereby, the variation in the coercive force of the produced soft magnetic alloy powder can be suppressed. As the reason for obtaining such an effect, when the volume resistivity is within the above range, it is considered that the stress strain is easily relaxed in the atomic arrangement or 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 as a whole for the soft magnetic alloy powder, it is possible to form fine crystal grains with uniform particle sizes. In addition, since particles that become defective due to insufficient or excessive heat treatment are unlikely to occur, a soft magnetic alloy powder that satisfies a predetermined coercive force and has stable quality can be efficiently produced.

[0076] 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 generation of oxides in the manufacturing process of the amorphous alloy powder and subsequent heat treatment is one method of reducing the volume resistivity.

[0077] The volume resistivity of the compacted powder is preferably 8.0×10 -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.

[0078] The method for measuring the volume resistivity of the compressed powder is as follows. First, 7.0 g of soft magnetic alloy powder is used as a sample and placed 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 using the resistivity meter connected to the unit. Note that a powder resistivity measurement system manufactured by Nitto Seiko Analytic Co., Ltd. is used for the powder resistivity measurement probe unit. Also, a low resistivity meter Loresta-GP manufactured by Nitto Seiko Analytic Co., Ltd. is used for the resistivity meter.

[0079] The heat treatment temperature is set to 420°C or higher and 620°C or lower, preferably 470°C or higher and 610°C or lower, and more preferably 500°C or higher and 600°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.

[0080] Note that if the heat treatment temperature is lower than 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.

[0081] 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.

[0082] Note that 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.

[0083] 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, 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 can be increased inside the heat treatment furnace. Thereby, 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.

[0084] 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 inter-particle distance. Therefore, it is considered that the thermal conductivity between particles is easily affected by pressure.

[0085] Note that 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.

[0086] 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.

[0087] 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 compacted powder can be suppressed. In addition, when an oxide film is formed, there is a possibility that stress strain is less likely to be relaxed. Based on this, 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.

[0088] Examples of the inert gas constituting the inert atmosphere include nitrogen gas, argon gas, and the like.

[0089] 3. Compressed Powder Core and Magnetic Element Next, the compressed powder core and magnetic element according to the embodiment will be described.

[0090] The magnetic element according to the embodiment is applicable to various magnetic elements provided with 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.

[0091] 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.

[0092] FIG. 2 is a plan view schematically showing a toroidal type coil component. The coil component 10 shown in FIG. 2 includes a ring-shaped compacted powder core 11 and a conductive wire 12 wound around the compacted powder core 11.

[0093] 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.

[0094] In addition, 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.

[0095] 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., and phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, cadmium phosphate, and inorganic materials such as silicates such as sodium silicate.

[0096] 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. In addition, an insulating film is provided on the surface of the conductive wire 12 as necessary.

[0097] Note that the shape of the compacted powder core 11 is not limited to the ring shape shown in FIG. 2, 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.

[0098] In addition, 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.

[0099] 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. 3 is a perspective view showing schematically a closed - magnetic - circuit - type coil component.

[0100] 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.

[0101] The coil component 20 shown in FIG. 3 includes a chip - shaped compacted powder core 21 and a conductor 22 which is 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 low iron loss.

[0102] Also, the coil component 20 includes such a compacted powder core 21. Such a coil component 20 has low iron loss and contributes to power saving of electronic devices.

[0103] Note that the compacted powder core 21 may contain, if necessary, soft magnetic powders or non - magnetic powders other than the soft magnetic alloy powder according to the above - described embodiment.

[0104] 4. Electronic Devices Next, an electronic device including the magnetic element according to the embodiment will be described with reference to FIGS. 4 to 6.

[0105] FIG. 4 is a perspective view showing a mobile - type personal computer which is an electronic device including the magnetic element according to the embodiment. The personal computer 1100 shown in FIG. 4 includes a main body 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 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.

[0106] FIG. 5 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. 5 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.

[0107] FIG. 6 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.

[0108] The digital still camera 1300 shown in FIG. 6 includes a display unit 100 provided on the back surface of a case 1302. The display unit 100 functions as a viewfinder for displaying a subject as an electronic image. Further, on the front side of the case 1302, i.e., the back side in the drawing, a light receiving unit 1304 including an optical lens, a CCD, etc. is provided.

[0109] When a photographer checks 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.

[0110] In addition, as the electronic device according to the embodiment, in addition to the personal computer in FIG. 4, the smartphone in FIG. 5, and the digital still camera in FIG. 6, 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.

[0111] Such an electronic device includes 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.

[0112] 5. Effects achieved 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 1-z Cr z ) y ) 100-x-a-b[a, b, x, y, and z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, and 0.015 ≤ z ≤ 0.185.] A powder manufacturing step S102 for manufacturing an amorphous alloy powder composed of the composition and impurities and 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 a heat treatment on the amorphous alloy powder at a temperature of 420°C or more and 620°C or less to manufacture a soft magnetic alloy powder. And the crystal grain size measured by the X-ray diffraction method for the soft magnetic alloy powder is 5.0 nm or more and 20.0 nm or less. Also, when the soft magnetic alloy powder is pressurized 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 9.0×10 -3 [Ω·cm] or less.

[0113] According to such a configuration, the stress strain of the amorphous alloy powder can be sufficiently relaxed, and a soft magnetic alloy powder with a low coercive force can be manufactured. Also, a soft magnetic alloy powder with little variation in coercive force and stable quality can be obtained.

[0114] In the method for manufacturing a soft magnetic alloy powder according to the above embodiment, the heat treatment time is 5 minutes or more and 60 minutes or less.

[0115] According to such a configuration, the amorphous alloy powder can be appropriately crystallized, and the stress strain can be sufficiently relaxed.

[0116] In the method for manufacturing 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.

[0117] According to such a configuration, a soft magnetic alloy powder capable of manufacturing a powder core with a particularly low coercive force and sufficiently suppressing the hysteresis loss can be obtained.

[0118] Also, in the method for manufacturing 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.

[0119] 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 interparticle 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.

[0120] Also, in the method for manufacturing the soft magnetic alloy powder according to the embodiment, the heat treatment is performed in an inert atmosphere with an oxygen volume concentration of 1500 ppm or less.

[0121] 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 relaxation of stress strain.

[0122] Also, the soft magnetic alloy powder according to the embodiment has a composition formula Fe x Cu a Nb b (Si 1-y (B 1-z Cr z ) y ) 100-x-a-b [a, b, x, y, z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.185, .] and is composed of impurities, has an average particle size of 10.0 μm or more and 45.0 μm or less, has a crystal grain size measured by the X-ray diffraction method of 5.0 nm or more and 20.0 nm or less, when a green compact with a mass of 7.0 g is produced by being pressed at a pressure of 63.7 MPa, the volume resistivity of the green compact is 9.0×10 -3is below [[Ω·cm]].

[0123] According to such a configuration, soft magnetic alloy powder with low coercive force and little variation in coercive force can be obtained.

[0124] In addition, in the soft magnetic alloy powder according to the above embodiment, the Si content is 4.0 atomic % or more and 8.0 atomic % or less, the B content is 9.0 atomic % or more and 13.5 atomic % or less, and the Cr content is 0.5 atomic % or more and 2.2 atomic % or less.

[0125] According to such a configuration, the magnetic permeability of the soft magnetic alloy powder can be further increased and the coercive force can be further decreased.

[0126] In addition, the soft magnetic alloy powder according to the above 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.

[0127] According to such a configuration, soft magnetic alloy powder capable of manufacturing a compacted powder core that can sufficiently suppress hysteresis loss can be obtained.

[0128] In addition, the compacted powder core according to the above embodiment contains the soft magnetic alloy powder according to the above embodiment. According to such a configuration, a compacted powder core with low coercive force and low iron loss can be obtained.

[0129] In addition, the magnetic element according to the above embodiment includes the compacted powder core according to the above embodiment. According to such a configuration, it has low iron loss and can contribute to power saving of electronic devices.

[0130] In addition, the electronic device according to the above embodiment includes the magnetic element according to the above 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.

[0131] The above description has been given based on preferred embodiments of the method for manufacturing soft magnetic alloy powder, soft magnetic alloy powder, compacted powder core, magnetic element, and electronic device according to the present invention. However, 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 above embodiment is replaced with any component having a similar function, or those to which any component is added to the above embodiment.

[0132] Also, in the above embodiment, a compacted powder core has been described as an example of the use of the soft magnetic alloy powder according to the present invention. However, the examples of use are not limited thereto, and for example, magnetic devices such as magnetic fluids, magnetic shielding sheets, and magnetic heads may be used. Further, the shapes of the compacted powder core and magnetic element are not limited to those shown in the drawings, and may be any shape.

[0133] Also, the method for manufacturing the soft magnetic alloy powder according to the present invention may be one to which a process for any purpose is added to the above embodiment.

Examples

[0134] Next, specific examples of the present invention will be described. 6. Manufacture of Compacted Powder Core 6.1. Sample Nos. 1 to 15 First, the raw materials were melted in a high-frequency induction furnace and atomized by the rotating water flow atomization method to obtain amorphous alloy powder. Next, the obtained amorphous alloy powder was heat-treated under the conditions shown in Table 1. Thereby, soft magnetic alloy powder was obtained.

[0135] Next, classification was performed using a classifier with a mesh. The alloy composition of the soft magnetic alloy powder after classification is shown in Table 1.

[0136] Next, the classified soft magnetic alloy powder, epoxy resin as a binder, and toluene as an organic solvent were mixed to obtain a mixture. The addition amount of the epoxy resin was 2 parts by mass with respect to 100 parts by mass of the soft magnetic alloy powder.

[0137] 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.

[0138] Next, the obtained granulated powder was filled into a molding die, and a molded body was obtained based on the following molding conditions.

[0139] <Molding conditions> Molding method: Press molding Shape of molded body: Ring-shaped -Dimensions of molded body: Outer diameter 14mm, inner diameter 8mm, thickness 3mm Molding pressure: 0.5t / cm 2 (49MPa) ·Molding temperature: 70℃

[0140] Next, the compact was heated in an air atmosphere at a temperature of 150° C. for 0.50 hour to harden the binder, thereby obtaining a powder magnetic core.

[0141] The average particle size, crystal particle size, oxygen content, and volume resistivity of the green compact of the soft magnetic alloy powder used in the production of the dust core are shown in Table 2. The average particle size was measured using a particle size distribution measuring device using a laser diffraction method, Microtrac HRA9320-X100 manufactured by Nikkiso Co., Ltd.

[0142] 6.2. Samples No. 16 to 30 Powder cores were obtained in the same manner as for samples Nos. 1 to 15, except that soft magnetic alloy powders were used that were manufactured under the manufacturing conditions shown in Table 3 and had average particle size, crystal particle size, oxygen content, and volume resistivity of the compacted body that were the values shown in Table 4.

[0143] In Tables 1 to 4, among the soft magnetic alloy powders of each sample number, those whose manufacturing method corresponds to the present invention are indicated as "Examples", and those that do not correspond to the present invention are indicated as "Comparative Examples".

[0144]

Table 1

[0145]

Table 2

[0146]

Table 3

[0147]

Table 4

[0148] 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 Table 2 and Table 4.

[0149] 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 Table 2 and Table 4.

[0150] 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.

[0151] 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

[0152] 7.3 Permeability of Magnetic Element Using the compacted powder cores obtained in each example and each comparative example, magnetic elements were fabricated based on the following fabrication conditions.

[0153] · Constituent material of the conductor: Cu · Diameter of the conductor: 0.6 mm · Number of turns: 7 turns

[0154] Next, for the fabricated magnetic elements, the magnetic permeability was measured based on the following measurement conditions. · Measuring device: Impedance Analyzer 4294A manufactured by Keysight Technologies Co., Ltd. · Measurement frequency: 1 MHz

[0155] Then, the obtained magnetic permeability was evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 4.

[0156] A: The magnetic permeability is 24.0 or more B: The magnetic permeability is 22.5 or more and less than 24.0 C: The magnetic permeability is less than 22.5

[0157] 7.4. Iron loss of the magnetic element Using the compacted powder cores obtained in each example and each comparative example, magnetic elements were fabricated based on the following fabrication conditions.

[0158] · Constituent material of the conductor: Cu · Diameter of the conductor: 0.16 mm · Number of turns: 18 turns on the primary side and 18 turns on the secondary side

[0159] Next, for the fabricated magnetic elements, the iron loss was measured based on the following measurement conditions. The measurement results are shown in Tables 2 and 4.

[0160] · Measuring device: BH Analyzer SY-8218 manufactured by Iwasaki Telecommunications Co., Ltd. · Measurement frequency: 1 MHz · Maximum magnetic flux density: 20 mT

[0161] 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.

[0162] Furthermore, it was also confirmed that the soft magnetic alloy powders obtained in each example had good magnetic permeability and low iron loss.

Explanation of Reference Signs

[0163] 10…Coil component, 11…Compacted powder core, 12…Conductor, 20…Coil component, 21…Compacted powder core, 22…Conductor, 100…Display unit, 1000…Magnetic element, 1100…Personal computer, 1102…Keyboard, 1104…Main body part, 1106…Display unit, 1200…Smartphone, 1202…Operation button, 1204…Receiver, 1206…Microphone, 1300…Digital still camera, 1302…Case, 1304…Light receiving unit, 1306…Shutter button, 1308…Memory, 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 １－ｚ Cr ｚ ) ｙ ) １００－ｘ－ａ－ｂ [a, b, x, y, z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.

185. A powder manufacturing process for producing an amorphous alloy powder composed of the composition and impurities as described above, with an average particle size of 10.0 μm or more and 45.0 μm or less, and A heat treatment process for producing a soft magnetic alloy powder by crystallizing the amorphous alloy powder by performing a heat treatment on the amorphous alloy powder at a temperature of 420°C or more and 620°C or less, having The crystal grain size of the soft magnetic alloy powder measured by the X-ray diffraction method is 5.0 nm or more and 20.0 nm or less, When the soft magnetic alloy powder is pressurized 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 9.0×10 －３ [Ω·cm] or less, a method for producing a soft magnetic alloy powder, characterized by this.

2. The method for manufacturing 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 manufacturing 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 manufacturing 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 manufacturing 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 １－ｚ Cr ｚ ) ｙ ) １００－ｘ－ａ－ｂ [a, b, x, y, z satisfy 0.3 ≤ a ≤ 2.0, 2.0 ≤ b ≤ 4.0, 75.5 ≤ x ≤ 79.5, 0.55 ≤ y ≤ 0.91, 0.015 ≤ z ≤ 0.

185. Composed of the composition and impurities as described above, having an average particle size of 10.0 μm or more and 45.0 μm or less, and the crystal grain size measured by the X-ray diffraction method is 5.0 nm or more and 20.0 nm or less, When a compacted powder with a mass of 7.0 g is produced by being pressurized at a pressure of 63.7 MPa, the volume resistivity of the compacted powder is 9.0×10 －３ [Ω·cm] or less. A soft magnetic alloy powder characterized by this.

7. The soft magnetic alloy powder according to claim 6, wherein the Si content is 4.0 atomic% or more and 8.0 atomic% or less, the B content is 9.0 atomic% or more and 13.5 atomic% or less, and the Cr content is 0.5 atomic% or more and 2.2 atomic% or less.

8. The soft magnetic alloy powder according to claim 6, wherein the coercive force is 8.0 [A / m] (0.1 [Oe]) or more and 79.6 [A / m] (1.0 [Oe]) or less.

9. A compacted powder core comprising the soft magnetic alloy powder according to any one of claims 6 to 8.

10. A magnetic element comprising the compacted powder core according to claim 9.

11. An electronic device comprising the magnetic element according to claim 10.

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