alloy particles

Abstract

The present application provides an alloy particle having high saturation magnetic flux density and excellent corrosion resistance. In the alloy particle of the present application, the total amount of Fe and Co is 82.2 to 96.5 parts by mass, Co is 0 to 30.0 parts by mass, P is 0 to 4.5 parts by mass, B is more than 0 parts by mass and 5.0 parts by mass or less, C is 0 to 3.0 parts by mass, Si is 0 to 6.7 parts by mass, Ni is more than 0 parts by mass and 12.0 parts by mass or less, Cr is more than 0 parts by mass and 4.2 parts by mass or less, the total amount of Mo, W, Zr and Nb is 0 to 4.2 parts by mass, the sum of the parts by mass of P and the parts by mass of Cr is 7.4 parts by mass or less, the product of the parts by mass of Ni and the parts by mass of Cr is 0.5 or more, and the total amount of Fe, Co and Ni is 97.0 parts by mass or less. The above alloy particle includes an amorphous phase, and the volume ratio of the above amorphous phase is 70% or more.

Description

Technical Field

[0001] This invention relates to alloy particles. More specifically, it relates to soft magnetic alloy particles having high saturation magnetic flux density and excellent corrosion resistance. Background Technology

[0002] The demand for miniaturization of coil components (hereinafter also referred to as components) in inductors and reactors is increasing. These components, including coils and magnetic cores, convert current and magnetic flux. Miniaturization requires, for example, reducing the number of turns and radius of the coil, but this reduction results in a decrease in the component's inductance (a reduction in the amount of magnetic flux). This decrease in inductance can be compensated for by increasing the frequency of the current (switching frequency). Therefore, the component needs to operate at high frequencies.

[0003] Furthermore, in small components, to drastically increase inductance, a core containing a soft magnetic material with high permeability is typically used. This core generates energy losses (iron losses) accompanying changes in the magnetic field, and these energy losses increase with frequency. In particular, if the magnetic field within the core is changed at high frequencies, large eddy currents are generated within the core due to magnetic induction. As a result, at high frequencies, the Joule heating caused by eddy currents (eddy current losses) has a greater impact on the overall energy loss, making it difficult for the component to operate at high frequencies. To address this, one solution to reduce eddy current losses is to reduce the size of the soft magnetic material. Therefore, powders (also known as powders or alloy particles) are frequently used as soft magnetic materials for cores in high-frequency applications.

[0004] Furthermore, using materials with high volume resistivity in the magnetic core can reduce eddy current losses. In the same chemical composition, the amorphous phase has a higher volume resistivity than the crystalline phase; therefore, materials containing an amorphous phase are preferred for high-frequency applications.

[0005] Patent Document 1 discloses a technique for using powder containing such an amorphous phase in components. In this technique, the magnetic permeability of the powder is increased, and the magnetic properties are improved.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2005-307291 Summary of the Invention

[0009] However, besides having a large specific surface area, powders also contain amorphous phases that are easily oxidized. Therefore, powders containing amorphous phases tend to have lower corrosion resistance. In particular, reducing the powder particle size in high-frequency applications significantly reduces corrosion resistance.

[0010] Patent Document 1 discloses a powder containing Si as an element to improve corrosion resistance, and having a high-concentration Si layer on its surface. Patent Document 1 also discloses Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pt, Pd, and Au as arbitrary elements to improve the corrosion resistance of this powder; however, even when these elements are included, the powder does not exhibit sufficient corrosion resistance in a humid atmosphere. Thus, when the powder contains only elements to improve corrosion resistance, the required corrosion resistance based on the chemical composition is not very high, and this issue is not yet known.

[0011] Furthermore, in recent years, there has been a demand for components that operate under high currents. Flowing a large alternating current through a coil generates a stronger magnetic field; however, if the material's saturation magnetic flux density is low, magnetic saturation occurs, making it difficult for the component to function. However, when powders contain a large amount of amorphous phases that increase volume resistivity or elements that improve corrosion resistance, there is a problem of reduced saturation magnetic flux density.

[0012] Therefore, it is impossible to obtain powders with high saturation magnetic flux density and excellent corrosion resistance in the existing technology.

[0013] This invention was made in view of the above-mentioned problems, and its object is to provide alloy particles with high saturation magnetic flux density and excellent corrosion resistance. Another object of this invention is to provide a coil component comprising the above-mentioned alloy particles.

[0014] The alloy particles involved in the first embodiment of the present invention are alloy particles containing Fe, B, Ni, and Cr, and arbitrarily containing Mo, W, Zr, Nb, Co, P, C, and Si. When the total content of Fe, Co, B, Ni, P, C, Si, Nb, Cr, Mo, W, and Zr is set to 100 parts by mass, the total content of Fe and Co is: 82.2 to 96.5 parts by mass, Co: 0 to 30.0 parts by mass, P: 0 to 4.5 parts by mass, B: greater than 0 parts by mass and less than 5.0 parts by mass, C: 0 to 3.0 parts by mass, Si: 0 to 6.7 parts by mass, Ni: greater than 0 parts by mass and less than 12.0 parts by mass, Cr: greater than 0 parts by mass and less than 4.2 parts by mass, and Mo, W... The total mass of Zr and Nb is 0 to 4.2 parts by mass; the sum of the mass of P and Cr is 7.4 parts by mass or less; the product of the mass of Ni and Cr is 0.5 or more; the total mass of Fe, Co, and Ni is 97.0 parts by mass or less. When Ni is greater than 0 parts by mass and less than 7.4 parts by mass, the total mass of Fe, Co, and Ni must be 89.6 parts by mass or more. When Ni is greater than 7.4 parts by mass and less than 12.0 parts by mass, the difference obtained by subtracting the mass of Ni × 0.5 from the sum of the mass of Fe and Co must be 78.5 parts by mass or more. The above alloy particles contain an amorphous phase, and the volume proportion of the amorphous phase is 70% or more.

[0015] The alloy particles involved in the second embodiment of the present invention are alloy particles containing an amorphous phase. These alloy particles contain Fe, B, Ni, and Cr, and optionally Mo, W, Zr, Nb, Co, P, C, and Si. In the concentration distribution of the composition along the depth direction of the alloy particles, N1 > N2, the Ni concentration is (N1+N2)×0.5, and the average distance D from the surface is 1.3 nm or more (here, N1 is the Ni concentration at a depth of 0 nm from the surface, and N2 is the average Ni concentration in a region with a depth of 10 nm to 100 nm from the surface).

[0016] It should be noted that the alloy particles involved in the second embodiment of the present invention may include the characteristic points of the alloy particles involved in the first embodiment of the present invention.

[0017] The coil component of the present invention includes a magnetic core containing alloy particles of the present invention and a coil.

[0018] According to the present invention, alloy particles with high saturation magnetic flux density and excellent corrosion resistance can be provided. Therefore, a small coil component operating at high frequency and high current can be provided stably and flexibly. Consequently, the size of electronic devices that can operate at high currents can be reduced. Attached Figure Description

[0019] Figure 1 This is a perspective view schematically illustrating an example of an inductor as one embodiment of the coil component of the present invention.

[0020] Figure 2 It means Figure 1 The diagram shows a three-dimensional view of the internal structure of the inductor.

[0021] Figure 3 The results represent Auger electron spectroscopy (AES) results relative to the alloy particles of Example 5.

[0022] Figure 4 The results represent the AES values ​​relative to the alloy strip of Comparative Example 31.

[0023] Symbol Explanation

[0024] 14 magnetic cores

[0025] 15 Protective Layers

[0026] 16a, 16b External electrodes

[0027] 17 coils

[0028] Ends of 17a and 17b Detailed Implementation

[0029] The inventors have newly discovered that the corrosion resistance of powders can be significantly improved by combining Ni and Cr. Furthermore, they have newly discovered that, in the depth-direction concentration distribution based on Auger electron spectroscopy, Ni concentration near the powder surface can significantly improve the corrosion resistance of the powder. Based on these findings, the inventors have derived that even with the same amount of strongly magnetic elements, high corrosion resistance can be imparted to powders, and even with the same corrosion resistance, high saturation magnetic flux density can be imparted to powders, thus completing this invention.

[0030] Hereinafter, the alloy particles involved in the first embodiment of one embodiment of the present invention will be described.

[0031] First, the chemical composition of the alloy particles involved in this embodiment will be described. The alloy particles involved in this embodiment contain Fe, B, Ni, and Cr, and arbitrarily include Mo, W, Zr, Nb, Co, P, C, and Si. The following description is based on the premise that the above-mentioned elements are present.

[0032] In the following description, unless otherwise specified, "parts by mass" refers to the total content of Fe, Co, B, Ni, P, C, Si, Nb, Cr, Mo, W, and Zr as 100 parts by mass. Similarly, unless otherwise specified, "molar parts" refers to the total content of Fe, Co, B, Ni, P, C, Si, Nb, Cr, Mo, W, and Zr as 100 molar parts.

[0033] Total Fe and Co: 82.2 parts by weight to 96.5 parts by weight

[0034] Co: 0 parts by weight to 30.0 parts by weight.

[0035] Fe (iron) and Co (cobalt) possess strong magnetic properties, increasing the saturation magnetic flux density. Therefore, to obtain a sufficient saturation magnetic flux density, the total mass of Fe and Co needs to be 82.2 parts by mass or more. From the viewpoint of obtaining a higher saturation magnetic flux density, it is preferable that the total mass of Fe and Co is 82.5 parts by mass or more, more preferably 84.9 parts by mass or more. On the other hand, to obtain sufficient thermal stability of the amorphous phase, the total mass of Fe and Co needs to be 96.5 parts by mass or less. From the viewpoint of obtaining higher thermal stability of the amorphous phase, it is preferable that the total mass of Fe and Co is 92.5 parts by mass or less, more preferably 91.5 parts by mass or less. In particular, Fe is an essential element for obtaining a high saturation magnetic flux density without increasing costs. Therefore, the amount of Fe needs to be 52.2 parts by mass or more. Since Co has a high valence, it can be 0 parts by mass. That is, the alloy particles may not contain Co. Co alone has a lower saturation magnetic flux density than Fe, but because it interacts with Fe, it can significantly increase the saturation magnetic flux density. Therefore, from the viewpoint of increasing the saturation magnetic flux density, the amount of Co is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more. On the other hand, as the amount of Co increases, the increase in saturation magnetic flux density in the Co content decreases. Therefore, the amount of Co needs to be 30.0 parts by mass or less. In particular, the amount of Co is preferably 12.0 parts by mass or less, more preferably 10.0 parts by mass or less.

[0036] P: 0 parts by weight to 4.5 parts by weight.

[0037] Phosphorus (P) improves the thermal stability of the amorphous phase. The minimum amount of P is 0 parts by mass, meaning the alloy particles may not contain P. To sufficiently improve the thermal stability of the amorphous phase, the amount of P is preferably 0.3 parts by mass or more, more preferably 0.6 parts by mass or more. On the other hand, to obtain a sufficient saturation magnetic flux density, the amount of P needs to be 4.5 parts by mass or less. From the viewpoint of obtaining a higher saturation magnetic flux density, the amount of P is preferably 3.0 parts by mass or less, more preferably 1.4 parts by mass or less. The amount of P can be 0.1 parts by mass or more.

[0038] B: Greater than 0 parts by weight and less than 5.0 parts by weight.

[0039] Boron (B) is an element required to improve the thermal stability of amorphous phases. From the viewpoint of obtaining higher thermal stability of the amorphous phase, the amount of B is preferably 1.0 parts by mass or more, more preferably 1.2 parts by mass or more. On the other hand, to obtain sufficient saturation magnetic flux density, the amount of B needs to be 5.0 parts by mass or less. From the viewpoint of obtaining higher saturation magnetic flux density, the amount of B is preferably 4.0 parts by mass or less. The amount of B can be 0.1 parts by mass or more.

[0040] C: 0 parts by weight to 3.0 parts by weight.

[0041] Carbon (C) improves the thermal stability of the amorphous phase. The minimum amount of C is 0 parts by mass. That is, the alloy particles may not contain C. To sufficiently improve the thermal stability of the amorphous phase, the total amount of B and C is preferably 1.0 parts by mass or more. From the viewpoint of obtaining higher thermal stability of the amorphous phase, the amount of C is preferably 1.0 parts by mass or more, and the total amount of B and C is more preferably 2.0 parts by mass or more. On the other hand, to obtain sufficient saturation magnetic flux density, the amount of C needs to be 3.0 parts by mass or less. In addition, if there is too much C, the Fe3C phase is easily formed, so to obtain thermal stability of the amorphous phase, the amount of C needs to be 3.0 parts by mass or less. From the viewpoint of obtaining higher saturation magnetic flux density, the amount of C is preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less. The total amount of B and C is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and even more preferably 4.2 parts by mass or less. The amount of C can be 0.1 parts by mass or more.

[0042] Si: 0 parts by mass to 6.7 parts by mass.

[0043] Silicon (Si) improves the thermal stability of the amorphous phase. The minimum amount of Si is 0 parts by mass, meaning the alloy particles may not contain Si. From the viewpoint of obtaining higher thermal stability of the amorphous phase, the amount of Si is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more. On the other hand, to obtain sufficient saturation magnetic flux density, the amount of Si needs to be 6.7 parts by mass or less. From the viewpoint of obtaining higher saturation magnetic flux density, the amount of Si is preferably 4.0 parts by mass or less. The amount of Si can be 0.1 parts by mass or more.

[0044] Ni: greater than 0 parts by mass and less than 12.0 parts by mass

[0045] The total of Fe, Co, and Ni is less than 97.0 parts by mass.

[0046] When Ni is greater than 0 parts by mass and less than 7.4 parts by mass: the total of Fe, Co and Ni is greater than 89.6 parts by mass.

[0047] When Ni is greater than 7.4 parts by mass and less than 12.0 parts by mass: the difference obtained by subtracting the mass of Ni × 0.5 from the sum of the mass of Fe and Co is greater than 78.5 parts by mass.

[0048] Ni (Ni) is an element required to improve corrosion resistance. Ni exhibits significant corrosion resistance by being added to chemical compositions containing boron (B). From the viewpoint of obtaining even higher corrosion resistance, it is preferable that the amount of Ni is 2.0 parts by mass or more, more preferably 3.6 parts by mass or more. The amount of Ni can be 0.1 parts by mass or more.

[0049] If there is too much Ni, the saturation magnetic flux density and Curie point will decrease, and the amorphous forming ability will also decrease. Therefore, the amount of Ni should be 12.0 parts by mass or less. To sufficiently improve the thermal stability of the amorphous phase, the total amount of Fe, Co, and Ni should be 97.0 parts by mass or less. From the viewpoint of obtaining a higher saturation magnetic flux density, the amount of Ni is preferably 10.0 parts by mass or less, and more preferably 9.0 parts by mass or less. In particular, when Ni is greater than 7.4 parts by mass and less than 12.0 parts by mass, in order to obtain a high magnetic flux density, the difference obtained by subtracting the mass of Ni × 0.5 from the sum of the mass of Fe and Co should be 78.5 parts by mass or more. When Ni is greater than 0 parts by mass and less than 7.4 parts by mass, the total amount of Fe, Co, and Ni should be 89.6 parts by mass or more.

[0050] Cr: greater than 0 parts by weight and less than 4.2 parts by weight

[0051] The sum of the mass fractions of P and Cr is less than 7.4 parts by mass.

[0052] The product of the mass fraction of Ni and the mass fraction of Cr is 0.5 or more.

[0053] Chromium (Cr) significantly improves corrosion resistance when combined with phosphorus (P). Therefore, Cr is desirable. Furthermore, the inclusion of Cr allows Ni to concentrate near the surface of the alloy particles, resulting in even higher corrosion resistance. Therefore, the product of the mass fraction of Cr and the mass fraction of Ni needs to be 0.5 or more. On the other hand, to obtain a sufficient saturation magnetic flux density, Cr needs to be 4.2 parts by mass or less. From the viewpoint of obtaining a higher saturation magnetic flux density, Cr is preferably 3.5 parts by mass or less, more preferably 2.5 parts by mass or less. To obtain a sufficient saturation magnetic flux density Bs, the sum of the mass fractions of P and Cr needs to be 7.4 parts by mass or less.

[0054] Mo, W, Zr and Nb total: 0 parts by mass to 4.2 parts by mass.

[0055] Mo, W, Zr, and Nb are any elements that can improve corrosion resistance. On the other hand, if the total amount of Mo, W, Zr, and Nb is too high, the saturation magnetic flux density decreases. Therefore, the total amount of Mo, W, Zr, and Nb needs to be 4.2 parts by mass or less. From the viewpoint of obtaining a higher saturation magnetic flux density Bs, the total amount of Mo, W, Zr, and Nb is preferably 2.0 parts by mass or less.

[0056] The alloy particles involved in this embodiment may contain elements other than Fe, Co, B, P, C, Si, Ni, Cr, Mo, W, Zr, and Nb as impurities. To improve the saturation magnetic flux density, the amount of impurities is preferably 1.0 parts by mass or less, more preferably 0.50 parts by mass or less. Furthermore, the amount of impurities is preferably 1.0 molar parts or less, more preferably 0.50 molar parts or less. Examples of impurities include N, O, Al, S, Ca, Ti, V, Cu, Mn, Zn, As, Ag, Sn, Sb, Hf, Ta, Bi, and rare earth elements (REMs). REMs are Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In particular, to reduce hysteresis loss and improve the thermal stability of the amorphous phase, Ca, Ti, and Al are preferably 0.1 parts by mass or less. Similarly, from the viewpoint of improving the thermal stability of the amorphous phase, the amount of Cu is preferably 0.04 parts by mass or less, or 0.04 moles or less, more preferably 0.02 parts by mass or less, or 0.02 moles or less. From the viewpoint of improving the saturation magnetic flux density, the amount of O is preferably 0.1 parts by mass or less, more preferably 0.05 parts by mass or less. The amount of impurities can be 0 parts by mass. That is, the alloy particles may not contain impurities.

[0057] The amount of each element was determined using a method that yields the aforementioned significant figures with precision. Specifically, the determination methods described in the examples below and equivalent determination methods were used for quantification.

[0058] Next, the internal structure of the alloy particles involved in this embodiment will be described.

[0059] Amorphous phases improve the volume resistivity and permeability of alloy particles, and reduce magnetic anisotropy and coercivity. Therefore, alloy particles need to contain an amorphous phase. The average volume proportion of this amorphous phase needs to be 70% or more, preferably 80% or more. The average volume proportion of the amorphous phase can be 100%. That is, the microstructure within the alloy particles is a microstructure composed of one or more amorphous phases or a multiphase microstructure of amorphous and crystalline phases. When the alloy particles contain a crystalline phase, in order to reduce coercivity, it is preferable that the average grain size of each phase of the crystalline phase obtained by solid diffusion is 30 nm or less, more preferably 25 nm or less. In addition, the crystalline phase is classified into alloy phase and compound phase. Alloy phases are, for example, body-centered cubic Fe phases or Fe-Si phases. In order to improve saturation magnetic flux density, the average volume proportion of the alloy phase can be 10% or more. In addition, in order to reduce coercivity, the average volume proportion of the compound phase is preferably 10% or less, more preferably 2% or less, and particularly preferably 1% or less. The average volume proportion of the compound phase can be 0%. Examples of compound phases include compounds such as Fe3P, Fe3B, Fe3C, Fe2B, oxides, and their solid solutions. The volume ratio of each phase is determined based on peak analysis of data obtained by X-ray diffraction (XRD). This peak analysis uses the method described in the examples below. Here, the alloy particles are used directly as the XRD sample without pulverization. Furthermore, when calculating the amount of amorphous phase using the method described in the examples below, it is defined as the alloy particles containing an amorphous phase.

[0060] Hereinafter, the alloy particles involved in the second embodiment, which is another embodiment of the present invention, will be described.

[0061] The surface structure of the alloy particles involved in this embodiment will be described.

[0062] In the depth-direction concentration distribution obtained using Auger electron spectroscopy, the corrosion resistance of the powder can be significantly improved if Ni is concentrated near the surface of the powder. Specifically, in the depth-direction composition concentration distribution of the alloy particles, determined by repeatedly analyzing the surface of the alloy particles using Auger electron spectroscopy and removing the surface using argon ion irradiation, N1 > N2. Here, N1 is the Ni concentration at a depth of 0 nm from the surface, and N2 is the average Ni concentration in the region from a depth of 10 nm to 100 nm from the surface. Furthermore, the alloy particles must have a Ni concentration of (N1 + N2) × 0.5 and an average distance D from the surface of 1.3 nm or more. On the other hand, the distance D is, for example, 6.0 nm or less.

[0063] It should be noted that the concentration distribution was determined as the content (parts by mass) of each component when the total content of Fe, Co, Ni, P, B, C, Si, Nb, Cr, Mo, W, Zr and O was set to 100 parts by mass.

[0064] The concentration distribution of the alloy particles in the depth direction is measured, for example, at 1.1 nm intervals for the range of depths above 0 nm and below 11 nm, and at 2.2 nm intervals for the range of depths above 11 nm and below 100 nm. The concentration data of adjacent particles in the depth direction are connected by a linear equation.

[0065] When using Auger electron spectroscopy (AES) for measurement, the measured values ​​at a depth of 0 nm exhibit significant inhomogeneity in the acquired spectroscopic spectrum. Therefore, it is preferable to perform only two measurements at the 0 nm depth and calculate the average value. Furthermore, to improve the SN ratio, the number of measurements can be increased to obtain the average value.

[0066] If the surface structure of the alloy particles has the aforementioned characteristics, the elements contained in the group consisting of Ni and Cr will form a sound passivation film, significantly improving corrosion resistance.

[0067] Here, the alloy particles measured using Auger electron spectroscopy were 10, and the average concentration distribution of these 10 alloy particles was used.

[0068] The internal structure of the alloy particles involved in this embodiment will be described.

[0069] In this embodiment, the alloy particles contain an amorphous phase, similar to the first embodiment.

[0070] It should be noted that, as a variation of the second embodiment, the second embodiment may include the feature points of the first embodiment.

[0071] Furthermore, more preferred embodiments of the first embodiment, the second embodiment, and variations thereof will be described.

[0072] The size and shape of the alloy particles involved in this embodiment will be described.

[0073] The size of the alloy particles is arbitrary. To improve the energy efficiency in the frequency band of the coil components and the effective permeability of the core, the D50 of the alloy particles is preferably 1 μm to 50 μm, more preferably 20 μm to 40 μm. Especially when energy efficiency at high frequencies and the fill rate of the alloy particles are important, the D50 of the alloy particles is preferably 1 μm to 10 μm, more preferably 1 μm to 6 μm. In addition, to facilitate the molding of the core or to ensure the insulation of the coil components, the D90 of the alloy particles is preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 60 μm or less. The D90 of the alloy particles can be 1 μm or more. Here, D50 and D90 refer to the particle sizes in the volumetric particle size distribution where the cumulative frequency from the smallest particle size is 50% and 90%, respectively.

[0074] Similarly, the shape of the alloy particles is arbitrary. For example, when actively utilizing shape magnetic anisotropy, the aspect ratio can be 0.10 to 0.70. On the other hand, in order to improve the permeability of the coil components even without considering anisotropy, the aspect ratio can be 0.70 to 1.0. When the filling rate of the alloy particles is important, the aspect ratio is preferably 0.70 to 0.95, more preferably 0.75 to 0.90. Here, the aspect ratio is the ratio of the minor axis length to the major axis length of the two-dimensional projection image of the alloy particles, which is obtained by averaging the values ​​obtained from at least 10 alloy particles.

[0075] The surface microstructure and surface coating of the alloy particles involved in this embodiment will be described.

[0076] In addition to the passivation film, a secondary film can be formed on the surface of the alloy particles as needed. To improve the insulation between alloy particles, the film can be an oxide or a nitride. The film is preferably a phosphate or an oxide containing Si. The method of forming the film is not limited, but for high insulation, the sol-gel method or the mechanochemical reaction method is preferred.

[0077] The internal stress of the alloy particles involved in this embodiment will be explained.

[0078] To reduce coercivity, the internal stress of the alloy particles is preferably low, but quantifying the internal stress is difficult. Therefore, considering the influence of internal stress on coercivity, the coercivity of the alloy particles is preferably 500 A / m or less, more preferably 200 A / m or less, and even more preferably 100 A / m or less. The coercivity of the alloy particles can be 0.0 A / m or more, or 0.1 A / m or more.

[0079] The magnetic core according to one embodiment of the present invention will be described below.

[0080] The magnetic core involved in this embodiment includes the alloy particles involved in the above embodiments. For stable bonding, the magnetic core may include resin. Furthermore, the resin may be selected from at least one of epoxy resin, phenolic resin, and silicone resin. Moreover, the magnetic core may include magnetic materials other than the alloy particles of the above embodiments, and may also include non-magnetic materials such as oxides.

[0081] The coil component according to one embodiment of the present invention will be described below.

[0082] The coil components involved in this embodiment include the magnetic core and coil involved in the above embodiments. The coil can be wound around the outer circumference of the magnetic core or wrapped inside the magnetic core. Examples of coil components include inductors, reactors, and components containing these (e.g., DC-DC converters).

[0083] Figure 1 This is a perspective view schematically illustrating an example of an inductor as one embodiment of the coil component of the present invention.

[0084] exist Figure 1 In the inductor shown, a protective layer 15 is formed approximately at the center of the surface of a rectangular magnetic core 14, and a pair of external electrodes 16a and 16b are formed at both ends of the surface of the magnetic core 14 in a manner that holds the protective layer 15.

[0085] Figure 2 It means Figure 1 The diagram shows a three-dimensional view of the internal structure of the inductor. Figure 2 For ease of explanation, the protective layer 15, external electrode 16a, and external electrode 16b are omitted.

[0086] The magnetic core 14 is formed, for example, from a composite material containing, as a main component, the alloy particles of the present invention and a resin material containing epoxy resin or the like. A coil 17 is embedded in the magnetic core 14.

[0087] It should be noted that the content of alloy particles in the composite material is not particularly limited, but is preferably 60% by volume or more. If the content of alloy particles is less than 60% by volume, the magnetic permeability and saturation magnetic flux density will decrease due to the insufficient content of alloy particles, resulting in a decrease in magnetic properties. In addition, the upper limit of the alloy particle content is only required to contain enough alloy particles to achieve the desired effect of the resin material, and is therefore preferably 99% by volume or less.

[0088] The coil 17 is, for example, a cylindrical shape formed by winding a flat-angle wire into a coil. The ends 17a and 17b of the coil 17 are exposed on the end face of the magnetic core 14 so as to be electrically connected to external electrodes 16a and 16b respectively. The coil 17 is, for example, a flat-angle wire made of copper or the like, coated with an insulating resin such as polyester resin or polyamide-imide resin, and wound into a coil shape in a strip shape with a hollow core.

[0089] Figure 1 The inductor shown can be made, for example, using the following method.

[0090] First, the alloy particles and resin material of the present invention are mixed and dispersed to form a composite material. Next, the coil 17 is embedded in the composite material in a manner that seals the coil 17 within the composite material. Then, a molding process is performed, for example, using compression molding, to obtain a molded body with the coil 17 embedded within it. After removing the obtained molded body from the molding die, it is subjected to heat treatment and surface grinding to obtain the magnetic core 14 with the ends 17a and 17b of the coil 17 exposed at the end faces.

[0091] Next, an insulating resin is applied to the surface of the magnetic core 14 outside the formation sites of the external electrodes 16a and 16b, and then cured to form a protective layer 15.

[0092] Subsequently, external electrodes 16a and 16b, made primarily of conductive material, are formed at both ends of the magnetic core 14. This process creates an inductor.

[0093] There are no particular limitations on the method of forming the external electrodes 16a and 16b. For example, they can be formed by any method such as coating, plating, or thin film formation.

[0094] Figure 1 The inductor shown has coil 17 embedded in magnetic core 14, and magnetic core 14 contains the aforementioned alloy particles as the main component. Therefore, it is possible to obtain a high-purity and high-quality coil component with high saturation magnetic flux density, low magnetic loss, strong magnetism and low hysteresis characteristics with good soft magnetic properties.

[0095] In the above embodiments, coil components such as inductors are exemplified as devices using the alloy particles of the present invention. However, the alloy particles of the present invention have high saturation magnetic flux density and low magnetic loss, and therefore can also be applied to stator cores or rotor cores equipped in motors. A motor typically comprises: a stator core with multiple armature teeth arranged at equal intervals on the same circumference, a coil wound around the armature teeth, and a rotor core rotatably disposed inside the stator core. As described above, the alloy particles of the present invention have high saturation magnetic flux density and low magnetic loss; therefore, by using the alloy particles of the present invention as a main component in at least one of the stator core and the rotor core, preferably both, a high-quality motor with low power loss can be obtained.

[0096] The following describes an electronic device according to one embodiment of the present invention.

[0097] The electronic device involved in this embodiment includes the coil component involved in the above embodiments. Examples of electronic devices include smartphones, tablets, personal computers, servers, and communication devices. In addition, examples of devices that include electronic devices include electric vehicles, hybrid vehicles, two-wheeled vehicles, aircraft, and railways.

[0098] The following describes a method for manufacturing alloy particles according to one embodiment of the present invention.

[0099] The method for manufacturing alloy particles involved in this embodiment includes a dissolution step and a solidification step.

[0100] In the dissolution step, the raw materials are heated and dissolved to produce molten metal. The chemical composition of the molten metal can be controlled by selecting multiple raw materials to achieve a specified chemical composition, or by refining the molten metal. Alternatively, a master alloy or its pulverized form, prepared by pre-dissolving and solidifying, can be used as a raw material in a manner that facilitates the formulation of the chemical composition. Furthermore, molten metals with different chemical compositions can be mixed to prepare a target molten metal. Examples of raw materials include pure iron, pig iron, iron-based waste, ferroalloys (ferroborone, ferrophosphorus, ferrosilicon, ferrochrome), graphite, phosphorus monomer, and metallic chromium. In particular, the chemical composition of the molten metal can be the chemical composition described in the first embodiment. Molten metals with this chemical composition are particularly effective in significantly reducing the oxidation of alloy particles after spraying in water. The heating method can be indirect resistance heating, induction heating, or electric arc heating.

[0101] To achieve a uniform chemical composition and obtain alloy particles containing an amorphous phase, the temperature of the molten metal needs to be higher than the liquidus temperature. Furthermore, to improve the cooling efficiency of the solidification step and stably generate the amorphous phase, the temperature of the molten metal is preferably lower than the liquidus temperature plus 500°C.

[0102] To ensure a uniform chemical composition of the molten metal, the dissolution step preferably involves maintaining the molten metal at the target molten metal temperature for a specified time. For example, this time is preferably 1 minute or more, more preferably 5 minutes or more. Furthermore, to reduce the escape of elements with high vapor pressure and the dissolution of gases from the atmosphere into the molten metal, the time is preferably 60 minutes or less, more preferably 30 minutes or less.

[0103] The atmosphere in contact with the molten metal can be atmospheric. To improve the yield of alloy particles, the atmosphere can be an inert gas atmosphere including nitrogen and argon, or an atmosphere that controls the oxygen potential.

[0104] In the solidification step, molten metal is pulverized into droplets, which are then solidified to form alloy particles. A spraying method can be applied to both the pulverization and solidification of the molten metal. Examples of spraying methods include water spraying, gas spraying, disc spraying, flame spraying, and combinations thereof. Alternatively, molten metal can be pulverized using gas spraying or flame spraying, and then rapidly cooled by water spraying. The fluid used in the spraying method can be water, an inert gas, or a gas containing water mist. The fluid supply rate absorbs the heat from the molten metal and is set within a range sufficient for the formation of an amorphous phase during the solidification of the molten metal. In particular, water, with its high cooling capacity, is especially preferred for the stable formation of the amorphous phase.

[0105] When the solidification step is a water spray method, a water pressure of 20 MPa to 250 MPa is required. If the water pressure is lower than 20 MPa, the volume proportion of the amorphous phase in the resulting alloy particles is low, and the coercivity becomes high. If the water pressure exceeds 250 MPa, the average particle size of the alloy particles becomes too small, thus the space filling rate of the alloy particles decreases, and the inductance of the coil components decreases. In the case of a chemical composition with low amorphous forming ability, it is preferable to crush the molten metal under high water pressure. Therefore, a water pressure of 50 MPa to 250 MPa is preferred. Furthermore, in the case of a chemical composition with low amorphous forming ability, a water pressure of 70 MPa to 250 MPa is preferred.

[0106] The method for manufacturing alloy particles according to this embodiment may further include a drying step after the solidification step. This drying step is preferably after the solidification step. For example, when water is used in the solidification step, to improve the energy efficiency of drying, alloy particles (mud pump) obtained by wetting a mixture of water and alloy particles using a separation method such as a cyclone separator, filtration, or sedimentation can be obtained. In this mud pump, since the alloy particles are in contact with both water and gas, corrosion is easily carried out when the gas contains oxygen. Therefore, it is preferable to reduce the oxygen partial pressure to below 40 Pa. Furthermore, to reduce dissolved oxygen in the water, an inert gas can be blown into the mixture of water and alloy particles used in the spray method. To reduce the area of ​​direct contact between oxygen in the atmosphere and the alloy particles, when the mass of the alloy particles in the mud pump is set to 100, the mass of water in the mud pump is preferably 5 to 100, more preferably 20 to 80.

[0107] Alloy particles can be dried by heating, depressurization, and combinations thereof. When drying by heating, to avoid a decrease in saturation magnetic flux density due to increased oxide content, it is preferable to have an oxygen partial pressure below 20 Pa and a temperature of 100°C to 250°C, more preferably an oxygen partial pressure below 2 Pa and a temperature of 120°C to 200°C. To prevent particle agglomeration, solidification, or adhesion to the drying container, stirring can be performed during drying. Furthermore, to remove agglomerated or solidified particles or particles adhered to the drying container, stress can be applied to the alloy particles after drying. Additionally, the drying step can be performed multiple times. It is believed that a passivation film forms on the surface of the alloy particles between the solidification step and the drying step.

[0108] The method for manufacturing alloy particles according to this embodiment may further include a classification step after the solidification step. This classification step may immediately follow any one of the following steps: solidification step, drying step, the blending step (described later), the heat treatment step (described later), or the surface treatment step (described later). In the classification step, the particle size distribution of the alloy particles is adjusted. For example, a vibrating screen, ultrasonic screen, or air classifier may be used to adjust the particle size distribution. The classification method may be based on differences in inertial forces, weight ratios, and flowability between particles. The desired particle size distribution preferably satisfies, for example, the suitable ranges of D50 and D90 described in the above embodiment. Furthermore, multiple classification steps may be performed.

[0109] The method for manufacturing alloy particles according to this embodiment may further include a blending step after the solidification step. This blending step may occur after any of the following steps: solidification step, drying step, grading step, heat treatment step (described later), or surface treatment step (described later). In this blending step, one or more powders are mixed together. The combination of mixed powders can be arbitrary, as long as at least one type of powder is obtained by the method for manufacturing alloy particles according to this embodiment. Two or more powders with different chemical compositions, microstructures, and particle size distributions can be mixed. For example, alloy particles with a D50 of 50 μm and alloy particles with a D50 of 4 μm can be mixed. As a soft magnetic material, for example, Fe-Si crystalline powder, Fe-Si-Cr crystalline powder, Fe-B amorphous powder, Fe-Si-B amorphous powder, Fe-Si-BP amorphous powder, iron powder, or nanocrystalline powder can be mixed with the alloy particles. As a non-magnetic material, inorganic fillers can be mixed with the alloy particles.

[0110] The method for manufacturing alloy particles according to this embodiment may further include a heat treatment step after the solidification step. This heat treatment step may be after any of the following steps: solidification step, drying step, grading step, fitting step, or surface treatment step (described later). In the heat treatment step, the alloy particles are heated to reduce internal stress contained within them. To ensure a sufficient amount of amorphous phase in the alloy particles, the heat treatment temperature needs to be set to a temperature lower than the crystallization initiation temperature. The heat treatment temperature is preferably at least 20°C lower than the crystallization initiation temperature. Furthermore, to sufficiently reduce internal stress, the heat treatment temperature is preferably at least 300°C. For example, the heat treatment temperature can be from 300°C to 550°C. The heating rate can be from 1°C / min to 5000°C / min. The crystallization initiation temperature varies depending on the heating rate; therefore, it is determined by differential scanning calorimetry (DSC) to determine the crystallization initiation temperature corresponding to the heating rate. The crystallization initiation temperature is determined by expanding the relationship between the heating rate and the crystallization initiation temperature determined by DSC towards higher heating rates, relative to heating rates that cannot be reached in DSC. Furthermore, to sufficiently reduce internal stress, the alloy particles are preferably maintained at a temperature above 300°C for at least 1 minute. This time is preferably 120 minutes or less to prevent the formation of coarse grains. To avoid a decrease in saturation magnetic flux density due to an increase in oxide content, the heat treatment atmosphere is preferably an inactive gas atmosphere that controls oxygen potential. For example, the oxygen partial pressure in the atmosphere is preferably below 100 Pa. Heating methods can include, for example, electromagnetic waves such as infrared radiation, or induction heating. Alternatively, the medium to be heated (solid, liquid, gas, or mixture) can be brought into contact with or near the alloy particles to heat them.

[0111] The method for manufacturing alloy particles according to this embodiment may further include a surface treatment step after the solidification step. This surface treatment step may be performed after any of the following steps: solidification, drying, grading, compounding, or heat treatment. In the surface treatment step, for example, chemical formation treatment, mechanochemical reaction, or sol-gel reaction may be used. Using the surface treatment step, an additional film can be formed on the surface of the alloy particles as needed.

[0112] The alloy particles involved in the first and second embodiments described above, and the alloy particles involved in these suitable embodiments, can be suitably manufactured according to the manufacturing method of the alloy particles involved in this embodiment, but can be manufactured using manufacturing methods other than those in this embodiment.

[0113] The following describes a method for manufacturing a magnetic core according to one embodiment of the present invention.

[0114] In a method for manufacturing a magnetic core according to one embodiment of the present invention, the alloy particles described in the above-described embodiments are used. The molding method may include, for example, pressure molding or molding. Specifically, molding methods such as cold-air uniaxial pressing, hot-air uniaxial pressing, spark plasma sintering (SPS), cold hydrostatic pressing, hot hydrostatic pressing, sheet molding, potting molding, transfer molding, and injection molding can be selected. Furthermore, additives such as binders can be mixed into the alloy particles described in the above-described embodiments. The binder may be at least one selected from epoxy resin, phenolic resin, and silicone resin. Other additives may include silane coupling agents, lubricants, curing accelerators, and curing retarders.

[0115] Example

[0116] The following describes embodiments of the invention in more detail. It should be noted that the invention is not limited to these embodiments.

[0117] (The production of alloy particles)

[0118] Taking into account the changes in chemical composition caused by slag formation during dissolution, the raw materials were weighed to obtain the alloy particles with the chemical compositions shown in Tables 1 and 3. The total weight of the raw materials was 150g. Myron (99.95wt%) manufactured by Toho Zinc Co., Ltd. was used as the Fe source. Materials manufactured by High Purity Chemical Research Institute Co., Ltd. were used as the B, C, Si, Ni, Cr, Mo, W, Zr, Nb, and Co sources. Block iron phosphide Fe3P (99wt%) was used as the P and Fe sources. Granular boron (99.5wt%) was used as the B source. Powdered graphite (99.95wt%) was used as the C source. Pure metals (99wt% or higher purity) were used as the Si, Ni, Cr, Mo, W, Zr, Nb, and Co sources.

[0119] The above-mentioned raw materials were placed in an alumina crucible and heated to 1400°C in an argon atmosphere at 1.0 atmosphere pressure using high-frequency induction heating. The raw materials were held at 1400°C for 10 minutes to prepare molten metal. This molten metal was then allowed to flow down through a hole at the bottom of the crucible, and alloy particles were formed from the molten metal using a water spray method. The alloy particles were then recovered in a precipitation tank. The water pressure for the water spray method was 80 MPa.

[0120] In Comparative Example 30, the chemical composition of the raw materials was the same as that in Example 30, but the water pressure was set to 0.5 times (40 MPa) of that in Example 30 during the spray operation.

[0121] After spraying, the sedimentation tank was allowed to stand for 30 minutes to allow the alloy particles in the dissolving tank to settle, and the mud-like alloy particles were recovered. In this mud-like alloy particle composition, the mass of the alloy particles was 100% and the mass of water was 50%. The mud-like alloy particles were heated to 200°C under a pressure below 1 Pa and maintained at 200°C for 180 minutes to dry the alloy particles. The dried alloy particles were then classified using a vibrating sieve, and the alloy particles between the 20μm and 53μm mesh sizes were recovered.

[0122] (D50 determination)

[0123] The average particle size D50 of the alloy particles was determined using a laser diffraction particle size distribution measuring device (Sympatec HELOS / RODOS). The dispersion pressure was 2 bar (200 kPa).

[0124] (Quantitative analysis of chemical composition)

[0125] The amounts of B and C contained in the alloy particles were determined by atomic absorption spectrometry. The amounts of elements other than B and C (Fe, P, Si, Ni, Cr, Mo, W, Zr, Nb, Co) were determined by inductively coupled plasma mass analysis (ICP-MS).

[0126] (Determination of the volume ratio Va of the amorphous phase)

[0127] The diffraction intensity distribution was obtained by directly measuring the Miniflex (Cu tube) X-ray diffraction apparatus manufactured by Rigaku Corporation using the θ-2θ method. The step size was set to 0.01°, the scanning speed was set to 5° / min, and the scanning range of 2θ was 25° to 90°. In the diffraction intensity distribution, near 2θ = 44°, a halo ring from the amorphous phase and a (110) peak from the (110) plane of the crystalline phase with a body-centered cubic structure and a peak of the compound phase were generated. Using the method described in Japanese Patent Application No. 2017-532527, the area intensity Ia of the halo ring and the area intensity Ic of the (110) peak and the area intensity Ic′ of the compound phase peak were calculated based on the diffraction intensity distribution, and the volume ratio Va of the amorphous phase was obtained using the following equation (1). It should be noted that the volume ratio Vc of the crystalline phase with a body-centered cubic structure can be obtained using the following equation (2).

[0128] Va=Ia / (Ia+Ic+Ic′) (1)

[0129] Vc=Ic / (Ia+Ic+Ic′) (2)

[0130] (Determination of surface concentration distribution)

[0131] For some of the embodiments and comparative examples, Auger electron spectrometry (AES) was used to determine the changes in chemical composition from the surface of the alloy particles to their depth. In this determination, surface analysis and surface removal based on argon ion irradiation were repeated sequentially. Measurements were performed at 1.1 nm intervals for depths greater than 0 nm and less than 11 nm, and at 2.2 nm intervals for depths from 11 nm to 100 nm. Measurements were performed twice only at a depth of 0 nm, and the average value was calculated. Measurements were performed once at depths other than 0 nm. Ten alloy particles were measured using AES, and the concentration distribution of these ten alloy particles was averaged for use.

[0132] (Determination of saturation magnetic flux density Bs)

[0133] Alloy particles were compacted and filled into a powder container. The saturation mass magnetization Ms of the alloy particles was determined using a vibrating sample magnetization measuring instrument (Dongying Industrial VSM-5-15) with a maximum magnetic field of 10 kOe.

[0134] In addition, the apparent density ρ was determined using a hydrometer (AccuPycII1340 manufactured by Shimadzu Corporation). He was used as the displacement gas, and 25g of alloy particles were used as the sample.

[0135] Based on the above saturated mass magnetization Ms and the above apparent density ρ, the saturated magnetic flux density Bs is calculated using the following equation (3).

[0136] Bs=4π×Ms×ρ (3)

[0137] (Determination of coercivity Hc)

[0138] Alloy particles were filled into a capsule for powder testing, and the capsule was compressed under a magnetic field to prevent the alloy particles from moving. The coercivity Hc of the alloy particles in the capsule was measured using a coercivity meter K-HC1000 manufactured by Tohoku Special Steel Co., Ltd.

[0139] (Corrosion potential E of alloy particles) corr and corrosion current density i corr (determination)

[0140] The corrosion potential (spontaneous potential) E of alloy particles was measured using an electrochemical measurement system (HZ-5000, manufactured by Hokuto Electric Co., Ltd.). corr and corrosion current density i corr The working electrode, reference electrode, and counter electrode were GRC-3155, RE-2, and CE-2 manufactured by EC Frontier Corporation. A mixture of alloy particles and carbon slurry (CPO [model 001010] manufactured by BAS Corporation) at a mass ratio of 2:1 was installed into the hole of the cylindrical working electrode. After immersing the working electrode in a 3% (w / w) NaCl aqueous solution for 1 hour, the spontaneous potential E was measured. corr Subsequently, a voltage was applied to the working electrode from its natural potential to +300mV to obtain the anodic polarization curve. The scan rate was set to 2mV / s, and the sampling interval was set to 2s. The corrosion current obtained from the anodic polarization curve was divided by the cross-sectional area of ​​the reference electrode, 0.0176cm². 2 Calculate the corrosion current density i corr It should be noted that the corrosion current density i corr The current density is defined at a potential of 100 mV applied as the corrosion potential. The corrosion potential is used as an indicator of corrosion resistance.

[0141] Tables 2 and 3 show the D50, Va, Bs, Hc, and E of the alloy particles. corr and i corr .

[0142] Table 1

[0143]

[0144] Table 2

[0145]

[0146]

[0147] In Examples 1-55, the alloy particles have the chemical composition and structure of the present invention, and possess high saturation magnetic flux density Bs and excellent corrosion resistance.

[0148] In Comparative Example 1, the saturation magnetic flux density Bs is small because the total mass fraction of P and Cr is large.

[0149] In Comparative Examples 2 and 3, the saturation magnetic flux density Bs is small because the total mass fraction of Fe and Co is small.

[0150] In Comparative Example 4, the coercivity Hc is greater because the total mass fraction of Fe and Co is greater.

[0151] In Comparative Examples 5-6, 8-9, and 24, the saturation magnetic flux density Bs is small because any one of P, B, C, or Si has a higher mass fraction.

[0152] In Comparative Example 7, because C has a larger mass fraction, the saturation magnetic flux density Bs is smaller and the coercivity Hc is larger.

[0153] In Comparative Example 8, due to the higher mass fraction of C, the saturation magnetic flux density Bs is smaller. Compared to Comparative Example 7, the lower mass fraction of C results in a volume ratio of over 70% for the amorphous phase Va, and a smaller coercivity Hc.

[0154] In Comparative Example 9, the saturation magnetic flux density Bs is small because Si has a higher mass fraction.

[0155] In Comparative Examples 10-11, due to the large amount of Ni, the saturation magnetic flux density Bs is small and the coercivity Hc is large.

[0156] Comparative Examples 12-13 and 15 have a higher Cr content, resulting in a lower saturation magnetic flux density Bs.

[0157] In Comparative Example 14, because of the large amount of Cr, the total amount of P by weight and Cr by weight is large, resulting in a small saturation magnetic flux density Bs and a large coercivity Hc.

[0158] In Comparative Examples 16-18, the product of the mass fraction of Ni and the mass fraction of Cr is smaller, resulting in a lower corrosion potential E, which is an indicator of corrosion resistance. corr Low. Additionally, the corrosion current density i corr high.

[0159] In Comparative Examples 19 and 20, the sum of the mass fractions of Fe, Co, and Ni is greater, resulting in a greater coercivity Hc.

[0160] In Comparative Examples 21 and 22, Ni is less, and the sum of the mass fractions of Fe, Co and Ni is small, resulting in a small saturation magnetic flux density Bs.

[0161] In Comparative Example 23, the difference between the sum of the mass fractions of Fe and Co and the mass fraction of Ni × 0.5 is small, resulting in a small saturation magnetic flux density Bs.

[0162] In Comparative Example 24, the saturation magnetic flux density Bs is small because of the higher mass fraction of C. Compared to Comparative Example 7, the mass fraction of C is smaller, and compared to Comparative Example 8, the mass fraction of Fe is smaller, while the mass fraction of B is larger. Therefore, the volume ratio Va of the amorphous phase is 100%, and the coercivity Hc is small.

[0163] In Comparative Example 25, due to the large amount of Nb, the saturation magnetic flux density Bs is high.

[0164] In Comparative Example 26, since it does not contain Cr, the corrosion potential E, which is an indicator of corrosion resistance, is... corr Low.

[0165] Comparative Example 27 has a large amount of Co, therefore the coercivity Hc is large.

[0166] Comparative Example 28 contains B, therefore its coercivity Hc is large.

[0167] In Comparative Example 29, because the product of the mass fraction of Ni and the mass fraction of Cr is small, the corrosion potential E, which is an indicator of corrosion resistance, is... corr Low.

[0168] In Comparative Example 30, the chemical composition of the alloy particles was the same as that of Example 30, but with a lower amorphous forming ability. Because the water pressure was set to 0.5 times that of Example 30 (40 MPa) under spray operation conditions, the volume proportion of the amorphous phase was small, and the coercivity Hc was large.

[0169] Comparative Example 31 is an alloy strip with the same composition as Example 5, produced using a single-roller rapid liquid cooling method. The same raw material as in Example 5 was placed in a quartz crucible and heated to 1400°C in an argon atmosphere at 1.0 atmospheres using high-frequency induction heating. The raw material was held at 1400°C for 10 minutes to form molten metal. This molten metal was discharged at a pressure of 0.015 MPa from a slit nozzle mounted at the lower part of a quartz nozzle onto the surface of a cooling copper roller. The cooling copper roller rotated at a circumferential speed of 25 m / s, and the molten metal was rapidly cooled and solidified to obtain a strip with an average width of 10 mm and an average thickness of 24 μm.

[0170] (Corrosion potential E of alloy strip) corr and corrosion current density i corr (determination)

[0171] The corrosion potential (spontaneous potential) E of alloy particles was measured using an electrochemical measurement system (HZ-5000, manufactured by Hokuto Electric Co., Ltd.).corr and corrosion current density i corr The reference electrode and counter electrode were RE-2 and CE-2 manufactured by EC Frontier Corporation, respectively. One end (20 mm) of an alloy strip up to 10 mm wide and 60 mm long was immersed in a 3% (w / w) NaCl aqueous solution. Using this alloy strip as the working electrode, the spontaneous potential E was measured. corr Subsequently, a voltage was applied to the working electrode from its natural potential up to +300mV to obtain the anodic polarization curve. The scan rate was set to 2mV / s, and the sampling interval was set to 2s. The corrosion current obtained from the anodic polarization curve was divided by the surface area of ​​the alloy strip, 4.0cm². 2 Calculate the corrosion current density i corr It should be noted that the corrosion current density i corr The corrosion potential is defined as the current density at which a potential of 100 mV is applied. It is used as an indicator of corrosion resistance.

[0172] Table 4 shows the Va, Bs, Hc, and E of the alloy ribbon of Comparative Example 31. corr and i corr .

[0173]

[0174] Table 5 shows the AES results for the alloy particles of Example 5 and Comparative Example 26, and the alloy strip of Comparative Example 31.

[0175] Table 5

[0176]

[0177] Figure 3 , Figure 4 The AES data for Example 5 and Comparative Example 31 are shown in the figure.

[0178] In Example 5, the Ni concentration N1 at a depth of 0 nm from the surface of the alloy particles and the Ni concentration N2, which is the average of the depths from the surface of the alloy particles from 10 nm to 100 nm, are in a relationship where N1 > N2. The average distance D from the surface of the alloy particles, which is the sum of N1 and N2 multiplied by 0.5 (N1 + N2) × 0.5, is greater than 1.3 nm. Therefore, the corrosion potential E, which is an indicator of corrosion resistance, is... corr It gets taller.

[0179] In Comparative Example 26, the Ni concentration N1 at a depth of 0 nm from the surface of the alloy particles and the Ni concentration N2 at an average depth of 10 nm to 100 nm from the surface of the alloy particles are in a relationship of N1 > N2. However, the average distance D from the surface of the alloy particles to the Ni concentration ((N1 + N2) × 0.5) multiplied by the sum of N1 and N2 is smaller than 1.3 nm. Therefore, the corrosion potential E, which is an indicator of corrosion resistance, is lower. corr It gets lower.

[0180] In Comparative Example 31, the Ni concentration N1 at a depth of 0 nm from the surface of the alloy strip and the Ni concentration N2 at an average depth of 10 nm to 100 nm from the surface of the alloy strip are in the relationship N1 < N2. Therefore, the corrosion potential E, which is an indicator of corrosion resistance, is... corr Low.

[0181] The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications can be made to the structure without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the foregoing description, nor by the claims.

Claims

1. An alloy particle comprising an amorphous phase, Contains Fe, B, Ni, and Cr, and may contain any of Mo, W, Zr, Nb, Co, P, C, and Si. In the concentration distribution of the alloy particles along the depth direction, N1 > N2, and the average distance D from the surface for a Ni concentration of (N1+N2)×0.5 is greater than 1.3 nm. N1 is the Ni concentration at a depth of 0 nm from the surface, and N2 is the average Ni concentration in the region from a depth of 10 nm to 100 nm from the surface.

2. The alloy particles as described in claim 1, wherein the total content of Fe, Co, B, Ni, P, C, Si, Nb, Cr, Mo, W, and Zr is set to 100 parts by mass. Total Fe and Co: 82.2 parts by weight to 96.5 parts by weight Co: 0 parts by weight to 30.0 parts by weight P: 0 parts by weight to 4.5 parts by weight B: Greater than 0 parts by weight and less than 5.0 parts by weight C: 0 parts by weight to 3.0 parts by weight Si: 0 parts by weight to 6.7 parts by weight Ni: greater than 0 parts by mass and less than 12.0 parts by mass Cr: greater than 0 parts by weight and less than 4.2 parts by weight Total of Mo, W, Zr and Nb: 0 parts by mass to 4.2 parts by mass. The sum of the mass fractions of P and Cr is less than 7.4 parts by mass. The product of the mass fraction of Ni and the mass fraction of Cr is 0.5 or more. Fe, Co, and Ni combined: less than 97.0 parts by mass. When Ni is greater than 0 parts by mass and less than 7.4 parts by mass, the total of Fe, Co, and Ni must be greater than 89.6 parts by mass. When Ni is greater than 7.4 parts by mass and less than 12.0 parts by mass, the difference obtained by subtracting the mass of Ni multiplied by 0.5 from the sum of the mass of Fe and Co must be greater than 78.5 parts by mass. The alloy particles contain an amorphous phase, and the volume proportion of the amorphous phase is more than 70%.

3. An alloy particle containing Fe, B, Ni, Cr, and P, and arbitrarily including Mo, W, Zr, Nb, Co, C, and Si. When the total content of Fe, Co, B, Ni, P, C, Si, Nb, Cr, Mo, W, and Zr is set to 100 parts by mass, Total Fe and Co: 82.2 parts by weight to 96.5 parts by weight Co: 0 parts by weight to 30.0 parts by weight P: greater than 0 parts by weight and less than 4.5 parts by weight B: Greater than 0 parts by weight and less than 5.0 parts by weight C: 0 parts by weight to 3.0 parts by weight Si: 0 parts by weight to 6.7 parts by weight Ni: greater than 0 parts by mass and less than 12.0 parts by mass Cr: greater than 0 parts by weight and less than 4.2 parts by weight Total of Mo, W, Zr and Nb: 0 parts by mass to 4.2 parts by mass. The sum of the mass fractions of P and Cr is less than 7.4 parts by mass. The product of the mass fraction of Ni and the mass fraction of Cr is 0.5 or more. Fe, Co, and Ni combined: less than 97.0 parts by mass. When Ni is greater than 0 parts by mass and less than 7.4 parts by mass, the total of Fe, Co, and Ni must be greater than 89.6 parts by mass. When Ni is greater than 7.4 parts by mass and less than 12.0 parts by mass, the difference obtained by subtracting the mass of Ni multiplied by 0.5 from the sum of the mass of Fe and Co must be greater than 78.5 parts by mass. The alloy particles contain an amorphous phase, and the volume proportion of the amorphous phase is more than 70%.

4. A coil component comprising a magnetic core and a coil containing alloy particles as described in any one of claims 1 to 3.

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