Soft magnetic alloy and magnetic component

Abstract

A soft magnetic alloy has an inner region having a soft magnetic alloy composition containing Fe and Co, a Co concentration region present closer to a surface side than the inner region and having a higher concentration of Co than the inner region, and an SB concentration region present closer to the surface side than the Co concentration region and having a higher concentration of at least one element selected from Si and B than the inner region.

Description

Technical Field

[0001] This invention relates to a soft magnetic alloy and a magnetic component using the soft magnetic alloy. Background Technology

[0002] Soft magnetic alloys, as shown in Patent Documents 1-3, are known as magnetic materials used in various magnetic components such as inductors. These soft magnetic alloys have a higher saturation magnetic flux density Bs than ferrite materials and possess excellent soft magnetic properties. However, soft magnetic alloys sometimes corrode due to storage conditions or the environment in which they are used, requiring improved corrosion resistance.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-293099

[0006] Patent Document 2: Japanese Patent Application Publication No. 2007-231415

[0007] Patent Document 3: Japanese Patent Application Publication No. 2014-167139 Summary of the Invention

[0008] The technical problem the invention aims to solve

[0009] The present invention was made in view of the above-mentioned actual situation, and its object is to provide a soft magnetic alloy with high corrosion resistance and a magnetic component using the soft magnetic alloy.

[0010] Means for solving technical problems

[0011] To achieve the above objectives, the present invention provides a soft magnetic alloy having:

[0012] The internal region is composed of a soft magnetic alloy containing Fe and Co;

[0013] A Co-concentrated region exists closer to the surface than the internal region, and the Co concentration is higher in this region than in the internal region; and

[0014] The SB enrichment region exists closer to the surface than the Co enrichment region, and the concentration of at least one element selected from Si and B is higher than that of the inner region.

[0015] The inventors conducted a special study and found that soft magnetic alloys with the above characteristics suppress rusting when immersed in water and improve corrosion resistance.

[0016] Preferably, the SB-concentrated region is an oxide phase. Furthermore, it is preferable that the SB-concentrated region is amorphous.

[0017] Preferably, the Co-enriched region is a metallic phase. Furthermore, it is preferable that the Co concentration in the Co-enriched region is greater than 1.2.

[0018] Preferably, the degree of amorphization of the above-mentioned soft magnetic alloy is 85% or higher.

[0019] The aforementioned soft magnetic alloys can be in the form of strips or powders.

[0020] The soft magnetic alloy of the present invention has no particular limitations in its application; for example, it can be used in various magnetic components such as inductors, filters, and antennas. Even in the above applications, the soft magnetic alloy of the present invention is suitable as a core material in coil components and the like. Attached Figure Description

[0021] Figure 1A This is an enlarged cross-sectional view of the main part of the soft magnetic alloy 1 according to one embodiment of the present invention.

[0022] Figure 1B This is an example of an enlarged cross-sectional view of the main part of the soft magnetic alloy 1a according to one embodiment of the present invention.

[0023] Figure 2A This is an example of a chart obtained through X-ray crystal structure analysis.

[0024] Figure 2B Through the Figure 2A The diagram shown is an example of a pattern obtained by contour fitting.

[0025] Figure 3 By along Figure 1A The measurement line L shown M Here is an example of a chart obtained by using line analysis with EDX.

[0026] Figure 4A This is a cross-sectional view of a soft magnetic alloy 1b according to one embodiment of the present invention.

[0027] Figure 4B It is Figure 4A The region shown is an enlarged cross-sectional view of IVB.

[0028] Figure 5A yes Figure 1A An example of an EELS image of the soft magnetic alloy 1 shown.

[0029] Figure 5B yes Figure 1B An example of an EELS image of the soft magnetic alloy 1a shown.

[0030] Figure 5C yes Figure 4A An example of a STEM image of the soft magnetic alloy 1b shown.

[0031] Symbol Explanation

[0032] 1, 1a, 1b... soft magnetic alloys

[0033] 2...internal area

[0034] 10...the most superficial

[0035] 11……Co Concentration Zone

[0036] 12……SB Concentration Zone

[0037] 13...Oxide layer

[0038] 20……Covering layer Detailed Implementation

[0039] The present invention will now be described in detail based on the embodiments shown in the accompanying drawings.

[0040] The soft magnetic alloy 1 of this embodiment can have a strip shape, a powder shape, or other block shape, and the shape of the soft magnetic alloy 1 is not particularly limited. Furthermore, the size of the soft magnetic alloy 1 is not particularly limited. For example, when the soft magnetic alloy 1 is in the shape of a strip, the thickness of the strip can be set to 15 μm to 100 μm; when the soft magnetic alloy 1 is in the shape of a powder, the average particle size of the soft magnetic alloy powder can be set to 0.5 μm to 150 μm, preferably 0.5 μm to 25 μm.

[0041] Furthermore, the aforementioned average particle size can be determined using various particle size analysis methods such as laser diffraction, but it is preferable to use a particle image analysis device, the Morphologi G3 (manufactured by Malvern Panalytical Co., Ltd.). In the Morphologi G3, soft magnetic alloy powder is dispersed in air, and the projected area of ​​the particles constituting the powder is measured. The particle size distribution obtained from the circular equivalent diameter is then calculated based on this projected area. Moreover, in the obtained particle size distribution, the average particle size is taken as the particle size at which the cumulative relative degree based on volume or number is 50%. Furthermore, when the soft magnetic alloy 1 is contained within a magnetic core, the average particle size of the soft magnetic alloy 1 (powder) can be calculated by observing the circular equivalent diameter of the particles contained in the cross-section using an electron microscope (SEM, STEM, etc.).

[0042] Figure 1A This is an enlarged cross-sectional view of the area near the surface of soft magnetic alloy 1. For example... Figure 1AAs shown, the soft magnetic alloy 1 has: an inner region 2, a Co-enriched region 11 located closer to the surface of the soft magnetic alloy 1 than the inner region 2, and an SB-enriched region 12 located closer to the surface of the soft magnetic alloy 1 than the Co-enriched region 11. Furthermore, in this embodiment, "inner side" refers to the side closer to the center of the soft magnetic alloy 1, and "surface side" or "outer side" refers to the side farther away from the center of the soft magnetic alloy 1.

[0043] (Internal Area 2)

[0044] The internal region 2 is the matrix portion of the soft magnetic alloy 1, comprising at least 90 vol% of its volume. Therefore, the average composition of the soft magnetic alloy 1 can be considered as the composition of the internal region 2, and the crystal structure of the soft magnetic alloy 1 can be considered as the crystal structure of the internal region 2. Furthermore, the aforementioned volume ratio of the internal region 2 can be replaced by an area ratio, meaning that at least 90% of the cross-sectional area of ​​the soft magnetic alloy 1 is the internal region 2.

[0045] The inner region 2 (i.e., the soft magnetic alloy 1) has a soft magnetic alloy composition containing Fe and Co, and the specific alloy composition is not particularly limited. For example, the inner region 2 can be a soft magnetic alloy with a crystalline system such as Fe-Co, Fe-Co-V, Fe-Co-Si, or Fe-Co-Si-Al. Furthermore, it is preferable that the inner region 2 contains P. Examples of soft magnetic alloys with a P-containing crystalline system include Fe-Co-Si-P alloys and Fe-Co-Si-P-Cr alloys. By containing P in the inner region 2, Co tends to concentrate at the outer edge of the inner region 2.

[0046] Furthermore, from the viewpoint of reducing coercivity, the internal region 2 preferably has an amorphous or nanocrystalline alloy composition. Examples of amorphous or nanocrystalline soft magnetic alloys include Fe-Co-PC alloys, Fe-Co-B alloys, or Fe-Co-B-Si alloys. More specifically, the internal region 2 preferably has a composition satisfying the formula ((Fe... (1-(α+β)) Co α Ni β ) 1-γ X1 γ ) (1-(a+b+c+d+e)) B a P b Si c C d Cr e The alloy composition, by having the above composition, easily yields amorphous, heteroamorphous, or nanocrystalline crystal structures.

[0047] In the above composition, B represents boron, P represents phosphorus, C represents carbon, and X1 is one or more elements selected from Ti, Zr, Hf, Nb, Ta, Mo, W, Al, Ga, Ag, Zn, S, Ca, Mg, V, Sn, As, Sb, Bi, N, O, Au, Cu, rare earth elements, and platinum group elements. Rare earth elements include Sc, Y, and lanthanum, while platinum group elements include Ru, Rh, Pd, Os, Ir, and Pt. Furthermore, α, β, γ, a, b, c, d, and e are atomic ratios, which preferably satisfy the following requirements.

[0048] The Co content relative to Fe (α) can be 0.005 ≤ α ≤ 0.700, or 0.010 ≤ α ≤ 0.600, or 0.030 ≤ α ≤ 0.600, or 0.050 ≤ α ≤ 0.600. Within the above ranges, Bs and corrosion resistance are improved. From the viewpoint of increasing Bs, 0.050 ≤ α ≤ 0.500 is preferred. The larger the α, the greater the tendency for improved corrosion resistance; however, if α is too large, Bs tends to decrease.

[0049] Furthermore, the Ni content relative to Fe (β) is 0 ≤ β ≤ 0.200. That is, it can be Ni-free, or it can be 0.005 ≤ β ≤ 0.200. From the perspective of increasing Bs, it can be 0 ≤ β ≤ 0.050, 0.001 ≤ β ≤ 0.050, or 0.005 ≤ β ≤ 0.010. The larger the β, the more likely the corrosion resistance will be improved, but if the β is too large, the Bs will decrease.

[0050] X1 can be present as an impurity or intentionally added. The content (γ) of X1 is 0 ≤ γ < 0.030. That is, relative to the total content of Fe, Co and Ni, X1 can replace the portion below 3.0%.

[0051] Furthermore, when the sum of the atomic ratios of the elements constituting the soft magnetic alloy is set to 1, the atomic ratio of the total content of Fe, Co, Ni, and X1 (1-(a+b+c+d+e)) is preferably 0.720≤(1-(a+b+c+d+e))≤0.950, more preferably 0.780≤(1-(a+b+c+d+e))≤0.890. By satisfying this condition, Bs can be easily increased. In addition, by setting it to 0.720≤(1-(a+b+c+d+e))≤0.890, an amorphous alloy is easily obtained.

[0052] a is the ratio of the number of atoms of B, preferably 0≤a≤0.200, and more preferably 0≤a≤0.150 from the viewpoint of increasing Bs.

[0053] b is the atomic ratio of P, preferably 0 ≤ b ≤ 0.100. That is, it may not contain P. From the viewpoint of balancing the improvement of Bs and corrosion resistance, it is more preferably 0.001 ≤ b ≤ 0.100, further preferably 0.005 ≤ b ≤ 0.080, and particularly preferably 0.005 ≤ b ≤ 0.050.

[0054] c is the atomic ratio of Si, preferably 0 ≤ c ≤ 0.150. That is, it may not contain Si, but from the viewpoint of balancing the improvement of Bs and corrosion resistance, it is more preferably 0.001 ≤ c ≤ 0.070.

[0055] d is the atomic ratio of C, preferably 0 ≤ d ≤ 0.050. That is, it may not contain C, but from the viewpoint of balancing the improvement of Bs and corrosion resistance, it is more preferably 0 ≤ d ≤ 0.020.

[0056] e is the atomic ratio of Cr, preferably 0 ≤ e ≤ 0.050. That is, from the viewpoint of improving Bs, it is possible to have no Cr, but from the viewpoint of balancing the improvement of Bs and corrosion resistance, it is more preferable to have 0.001 ≤ e ≤ 0.020.

[0057] The composition of the aforementioned internal region 2 (i.e., the composition of the soft magnetic alloy 1) can be analyzed using, for example, inductively coupled plasma optical emission spectrometry (ICP). In cases where it is difficult to determine the oxygen content via ICP, a pulsed heating melting extraction method can be used. Furthermore, if it is difficult to determine the carbon and sulfur content via ICP, an infrared absorption method can be used.

[0058] In addition to ICP, compositional analysis can also be performed using EDX (energy-dispersive X-ray diffraction) or EPMA (electron probe microanalysis) attached to an electron microscope. For example, for soft magnetic alloy 1 contained in a resin-containing magnetic core, compositional analysis is sometimes difficult using ICP; in such cases, EDX or EPMA can be used. Furthermore, if detailed compositional analysis is difficult to perform using any of the above methods, 3DAP (three-dimensional atomic probe microanalysis) can be used. When using 3DAP, the influence of resin components or surface oxidation can be eliminated, allowing the determination of the composition of the soft magnetic alloy 1, i.e., the internal region 2, within the analyzed area. This is because 3DAP allows the determination of an average composition by setting a small region (e.g., a region of φ20nm × 100nm) within the soft magnetic alloy 1.

[0059] Furthermore, when performing line analysis on the cross-section near the surface of the soft magnetic alloy 1 using EDX or EELS (electron energy loss spectroscopy), the internal region 2 can be identified as a region where the concentration of Fe or Co is stable (see reference). Figure 3Alternatively, for example, the average composition obtained by mapping analysis of the internal region 2 can be set as the composition of the soft magnetic alloy 1. In this case, the mapping analysis is performed using EDX or EELS, and the measurement site only needs to be set to a region at least 100 nm away from the surface of the soft magnetic alloy 1 in the depth direction (equivalent to the internal region 2), and the measurement field of view can be set to a range of approximately 256 nm × 256 nm.

[0060] The crystal structure of the internal region 2 (i.e., the crystal structure of the soft magnetic alloy 1) can be crystalline, nanocrystalline, or amorphous, but is more preferably amorphous. In other words, the degree of amorphization X of the internal region 2 (i.e., the degree of amorphization X of the soft magnetic alloy 1) is preferably 85% or more. A crystal structure with a degree of amorphization X of 85% or more is a structure that is substantially composed of amorphous material, or a structure composed of heteroamorphous material. Here, a structure composed of heteroamorphous material refers to a structure in which very little crystal is present in the amorphous material. That is, in this embodiment, "amorphous crystal structure" refers to a crystal structure with a degree of amorphization X of 85% or more, which may contain crystals within the range that satisfies the degree of amorphization X.

[0061] Furthermore, in the case of a structure composed of heteromorphic amorphous materials, the average crystal grain size of the crystals present in the amorphous material is preferably 0.1 nm or more and 10 nm or less. In addition, in this embodiment, "nanocrystalline" refers to a crystal structure with an amorphization degree X of less than 85% and an average crystal grain size of 100 nm or less (preferably 3 nm to 50 nm), and "crystalline material" refers to a crystal structure with an amorphization degree X of less than 85% and an average crystal grain size of more than 100 nm.

[0062] The degree of amorphization X can be determined by X-ray crystal structure analysis using XRD. Specifically, the 2θ / θ ratio of the soft magnetic alloy 1 of this embodiment was measured by XRD, and the results were as follows: Figure 2A The diagram shown is used. At this time, the measurement range of the diffraction angle 2θ is set to a range that can confirm the halo originating from the amorphous material, for example, preferably set to a range of 2θ = 30° to 60°.

[0063] Next, using the Lorentz function shown in equation (2) below, for Figure 2A A contour fit is performed on the chart shown. In this contour fit, it is preferable to set the error between the measured integral intensity generated by XRD and the integral intensity calculated using the Lorentz function to within 1%. Through this contour fit, the following is obtained: Figure 2B The crystal composition pattern α shown represents the crystalline scattering integral intensity Ic. c α represents the amorphous composition pattern representing the amorphous scattering integral intensity Ia. a and the pattern α that combines them c+aFurthermore, the degree of amorphization X can be obtained by incorporating the crystalline scattering integral intensity Ic and the amorphous scattering integral intensity Ia obtained here into the following equation (1).

[0064] X=100-(Ic / (Ic+Ia)×100)……(1)

[0065] Ic: Integral intensity of crystalline scattering

[0066] Ia: Integral intensity of amorphous scattering

[0067]

[0068] h: Peak height

[0069] u: Peak position

[0070] w: Half width

[0071] b: Background height

[0072] Furthermore, the method for determining the degree of amorphization X is not limited to the XRD method described above; it can also be determined by EBSD (crystallization orientation analysis) or electron beam diffraction.

[0073] (Co Concentration Zone 11)

[0074] The Co-enriched region 11 is a region where the Co concentration is higher than that of the internal region 2 described above. In this embodiment, the Co-enriched region 11 is preferably a continuous amorphous metallic phase extending from the internal region 2, covering at least a portion of the outer periphery of the internal region 2. In the cross-section of the soft magnetic alloy 1, the coverage ratio of the Co-enriched region 11 relative to the internal region 2 is not particularly limited, but can be set to 50% or more, more preferably 80% or more.

[0075] The presence and coverage of the Co-concentrated region 11 can be confirmed by observing the cross-section near the surface of the soft magnetic alloy 1 using STEM (scanning transmission electron microscopy) or TEM (transmission electron microscopy), and performing mapping analysis using EDX or EELS at this time. For example, Figure 5A The image shown (EELS image) is an example of the results of mapping analysis performed by EELS. Figure 5A The EELS image on the left shows the distribution of Co, with contrast indicating Co concentration. In this EELS image, inner region 2 can be identified as a region where Co concentration is almost negligible. Moreover, the contrast brightens at the edge of inner region 2, indicating a higher Co concentration than in inner region 2. This region with high Co concentration is Co concentration region 11, and its presence or absence can be confirmed using EELS images related to Co.

[0076] The average thickness t1 of the specific Co-concentrated region 11 obtained through this mapping analysis is preferably 0.3 nm or more. There is no particular upper limit to t1; for example, it can be set to 30.0 nm or less. By increasing t1 within this appropriate range, better results relative to corrosion resistance can be obtained. Furthermore, it is preferable to measure and calculate the average thickness t1 at at least three locations by changing the measurement field of view.

[0077] As mentioned above, the Co concentration region 11 is sometimes extremely thin. In a particular Co concentration region 11, it is preferable to use not only mapping analysis but also line analysis. Figure 3 Is the example along Figure 1A The measurement line L shown M A schematic diagram of the results of the line analysis is shown, with the vertical axis representing the detection intensity of each element (i.e., the intensity of the characteristic X-rays) and the horizontal axis representing the distance (depth) from the outermost surface (10). For example... Figure 3 As shown in the line analysis results, a peak indicating a higher Co concentration can be identified at the edge of the inner region 2 where the Fe or Co concentration is stable. This Co peak is located in the Co concentration region 11. In other words, a maximum Co concentration exists in the Co concentration region 11. The presence or absence of the aforementioned peak confirms the existence of the Co concentration region 11.

[0078] Furthermore, the Co-enriched region 11 where the aforementioned peak exists is preferably a metallic phase. The phase state of the Co-enriched region 11 can be confirmed by, for example, the line analysis, mapping analysis, or analysis using STEM or EELS attached to TEM, as described above. Specifically, when the Co-enriched region 11 is a metallic phase, in the line analysis or mapping analysis, the oxygen concentration in the Co-enriched region 11 is lower than the oxygen concentration in the SB-enriched region 12 described later (see reference). Figure 3 Furthermore, when analyzing the spectrum obtained via EELS, the ratio of Co in the oxide to metallic Co in the Co-enriched region 11 can be calculated. If the proportion of metallic Co is greater than that of the oxide, the Co-enriched region 11 is defined as a metallic phase. Additionally, in the TEM image of the transmitted wave, the contrast of the Co-enriched region 11 is darker than that of the SB-enriched region 12, which is an oxide phase, further confirming that the Co-enriched region 11 is a metallic phase.

[0079] Furthermore, in this embodiment, the Co concentration degree in the Co concentration region 11 is defined as the Co mass ratio (C11) of the Co concentration region 11. Co The ratio of Co mass to internal region 2 (C2) Co The ratio of (C11) Co / C2 CoThe Co concentration is preferably greater than 1.02, more preferably greater than 1.20. Furthermore, there is no particular upper limit to the Co concentration; for example, it can be set to 20 or less.

[0080] When a soft magnetic alloy consisting of an internal region 2 without Co concentration region 11 is used as a reference alloy, the corrosion resistance of the soft magnetic alloy 1 of this embodiment tends to increase relative to the reference alloy as the Co concentration increases. That is, a positive correlation can be observed between Co concentration and corrosion resistance. Furthermore, since the internal region 2 of the soft magnetic alloy 1 contains a predetermined amount of P, the Co concentration tends to increase easily, and the corrosion resistance tends to be further improved.

[0081] C2 used to calculate Co concentration Co and C11 Co The composition was determined using EELS analysis. Specifically, C2 Co This is the molar ratio of Co relative to the total amount of Fe and Co detected in internal region 2, calculated through EELS spectral analysis. Similarly, C11... Co This is the molar ratio of Co detected in Co concentration region 11 relative to the total amount of Fe and Co. That is, the molar ratio of Co in each region is expressed as Co / (Fe+Co), and to exclude the influence of impurities (elements introduced during sample preparation, etc.), the denominator is set to (Fe+Co). Furthermore, the resolution in this analysis is preferably set to 0.5 nm or less. Co Preferably, the measurement is performed at a depth of 0.2 μm or more from the outermost surface 10 of the soft magnetic alloy 1 into the interior. Furthermore, the Co concentration is preferably measured at at least five different fields of view, and the average value is calculated.

[0082] Furthermore, in the Co concentration region 11, Co is detected as the main constituent element, in addition to elements such as Fe that constitute the internal region 2. Moreover, in the Co concentration region 11, similar to the concentration of Co, the concentration of other elements can also occur, such as P. In this case, in mapping analysis or line analysis, high concentration regions of P are sometimes observed in a manner that repeats the region with high Co concentration.

[0083] (SB Concentration Zone 12)

[0084] The SB enrichment region 12 is a region where the concentration of at least one element selected from Si and B is higher than that of the inner region 2. The SB enrichment region 12 may be enriched by either Si or B, or by both Si and B. In this embodiment, the SB enrichment region 12 covers at least a portion of the outer periphery of the Co enrichment region 11. Furthermore, in locations where the Co enrichment region 11 is not present, the SB enrichment region 12 may sometimes be directly connected to and cover the inner region 2. The coverage ratio of the SB enrichment region 12 in the soft magnetic alloy 1 is not particularly limited; for example, it can be set to 50% or more, more preferably 80% or more.

[0085] Similar to Co-concentration region 11, the presence of SB-concentrated region 12 could be confirmed through mapping analysis using EDX or EELS. For example, as an example of the analysis results... Figure 5A The image on the right is an EELS image representing the distribution of B, measured at the same location as the EELS image (Co-L) on the left. In this EELS image, the concentration of B is represented by the contrast between light and dark areas, and it can be confirmed that the concentration of B becomes higher on the surface side of the Co-concentrated region 11 than in the inner region 2. Figure 5A In this case, the region with high B concentration is SB concentration region 12.

[0086] The average thickness t2 of the specific SB-concentrated region 12 obtained through this mapping analysis is preferably 0.5 nm or more. There is no particular upper limit to t2, for example, it can be set to 30 nm or less. Furthermore, for the average thickness t2, as with t1, it is preferable to change the measurement field of view and measure and calculate the thickness of the SB-concentrated region 12 at at least three locations.

[0087] Furthermore, the SB concentration region 12 is also preferably characterized using mapping analysis and line analysis. For example... Figure 3 As shown, in the line analysis results, peaks indicating the concentration of Si and / or B (including peaks containing Si and / or B maxima) can be identified closer to the surface than the Co peak. The location of these peaks is the SB enrichment region 12. More specifically, this can be determined based on the intensity of the characteristic X-rays induced by Si and B during line analysis. That is, if the intensity of the characteristic X-rays induced by Si and B in the SB enrichment region 12 is higher than that in the inner region 2, it can be determined that Si and / or B are enriched. Furthermore, as described above, in the mapping analysis, the elemental content can be mapped based on the intensity of each element; therefore, the SB enrichment region 12 can be identified based on the acquired mapping image.

[0088] Regarding the SB enrichment region 12, the degree of Si or B enrichment is represented by an intensity ratio, which is calculated using line analysis via EDX or EELS. Specifically, the detection intensity of Si in the SB enrichment region 12 is set as C12. S The detection intensity of Si in internal region 2 is set to C2. S C12 S / C2 S The Si intensity ratio (concentration degree) in the SB concentration region 12 is defined as follows. From a resolution point of view, this Si intensity ratio is preferably measured by EDX, and when Si is concentrated in the SB concentration region 12, the Si intensity ratio exceeds 1.0. In this embodiment, the Si intensity ratio is preferably 1.1 or more, and more preferably 1.2 or more. In addition, there is no particular upper limit to the Si intensity ratio, for example, it can be set to 20 or less.

[0089] Similarly, the detection intensity of B in the SB concentration region is set to C12. B Set the detection intensity of B in internal region 2 to C2. B C12 B / C2 B The intensity ratio (concentration degree) of B in the SB concentration region 12 is defined as follows. From the viewpoint of resolution, this intensity ratio of B is preferably measured by EELS, and when B is concentrated in the SB concentration region 12, the intensity ratio of B exceeds 1.0. In this embodiment, the intensity ratio of B is preferably 1.1 or more, and more preferably 1.2 or more. In addition, there is no particular limitation on the upper limit of the intensity ratio of B, for example, it can be set to 20 or less.

[0090] The SB enrichment region 12 is preferably an oxide phase. When the SB enrichment region 12 is an oxide phase, the above mapping analysis confirms that high-concentration oxygen regions repeatedly coexist with high-concentration Si and / or B regions. Furthermore, in the line analysis results, at the locations where Si and / or B peaks are present, the oxygen concentration becomes higher than in other regions (internal region 2, Co enrichment region 11). For example, in… Figure 3 The diagram shows the repetition of the Si concentration peak and the oxygen peak in the SB enrichment region 12. Furthermore, when the SB enrichment region 12 is an oxide phase, it can be identified as a region with a brighter contrast than the inner region 2 in the TEM image. Additionally, similar to the Co enrichment region 11, the phase state of the SB enrichment region 12 can be confirmed by analyzing (fitting) the spectrum obtained from EELS.

[0091] Furthermore, the SB-enriched region 12 is preferably amorphous. Here, the crystallinity of the SB-enriched region 12 is determined based on the presence or absence of spots caused by crystallization in the FFT (Fast Fourier Transform) pattern. That is, if no spots are detected in the FFT pattern of the SB-enriched region 12, it is determined to be amorphous; if spots are detected, it is determined to be crystalline. The FFT pattern can be obtained by observing the cross-section containing the SB-enriched region 12 using HRTEM (High Resolution Electron Microscopy) and performing Fast Fourier Transform processing on the obtained HRTEM image.

[0092] Alternatively, the crystallinity of the SB-concentrated region 12 can also be determined through image analysis of the HRTEM image. In the HRTEM image, based on phase contrast, a regularly arranged lattice can be identified in the crystalline region, while random, irregular patterns can be identified in the amorphous region. Therefore, by analyzing the HRTEM image, the area S of the SB-concentrated region 12 within the measurement field of view can be determined. SB The area S of the irregularly patterned region (i.e., the amorphous portion). SB amo able to serve as S SB amo Compared to S SB The area ratio of amorphous material is calculated by the ratio of the amorphous material to the area ratio of the SB-concentrated region 12. In this embodiment, the area ratio of amorphous material in the SB-concentrated region 12 is preferably 85% or more. If this condition is met, the SB-concentrated region 12 can be identified as amorphous.

[0093] In addition, the above-mentioned evaluation of crystallinity can also be carried out using the confined field method or nanobeam diffraction method in a small region.

[0094] Furthermore, in the SB concentration region 12, as described above, Si, B, and O can be detected, in addition to Fe and Co, which are constituent elements of the internal region 2.

[0095] As described above, the soft magnetic alloy 1 has a characteristic surface microstructure comprising Co-enriched regions 11 and SB-enriched regions 12. Particularly in this embodiment, such as Figure 1A As shown, the SB-enriched region 12 is located on the outermost surface and constitutes the outermost surface 10 of the soft magnetic alloy 1. However, other surface structures may also exist outside the SB-enriched region 12.

[0096] For example, such as Figure 1B The soft magnetic alloy 1a shown can also have an oxide layer 13 containing Fe formed to cover the surface side of the SB-concentrated region 12. In this case, the outermost surface 10 of the soft magnetic alloy 1a is composed of the oxide layer 13. In fact, Figure 5B yes Figure 1BAn example of an EELS image of the soft magnetic alloy 1a is shown. Figure 5B As shown, a region on the surface where the Fe concentration is higher than that of the SB-enriched region 12 can be identified. That is, in the oxide layer 13, the Fe concentration is higher than that of the Co-enriched region 11 and the SB-enriched region 12, and more preferably, the crystallization area is higher than that of the SB-enriched region 12. The oxide layer 13 with this characteristic is sometimes formed together with the Co-enriched region 11 and the SB-enriched region 12 during their formation. The average thickness t3 of the oxide layer 13 is preferably 1 nm or more. The upper limit of t3 is not particularly limited, for example, it can be set to 30 nm or less.

[0097] In addition, such as Figure 4A and Figure 4B The soft magnetic alloy 1b shown can also have an insulating cladding layer 20 formed on the outer side of the SB enrichment region 12 or the outer side of the oxide layer 13. In this case, the outermost surface 10 of the soft magnetic alloy 1b is composed of the cladding layer 20. In fact, Figure 5C yes Figure 4A An example of a STEM image of the soft magnetic alloy 1b is shown. In this STEM image, a bright contrast region can be identified on the outermost surface of the soft magnetic alloy 1b; this region is the coating layer 20. The coating layer 20 is a film formed by surface treatment such as coating after forming the Co-enriched region 11 and the SB-enriched region 12. Its average thickness is preferably 5 nm or more and 100 nm or less, more preferably 50 nm or less. Furthermore, as... Figure 4A As shown, this coating layer 20 is mostly formed on soft magnetic alloys in powder form, but it can also be formed on soft magnetic alloys in strip form.

[0098] Thus, in the surface structure of the soft magnetic alloy 1, in addition to the Co-enriched region 11 and the SB-enriched region 12, other layers (oxide layer 13, cladding layer 20, etc.) may be included. However, even when these other layers are present, the Co-enriched region 11 is present on the side connected to the inner region 2. Moreover, the vertical distance d1 from the outermost surface 10 to the Co-enriched region 11 is preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. In particular, when the cladding layer 20 is absent and the oxide layer 13 or the SB-enriched region 12 constitutes the outermost surface 10, the aforementioned vertical distance d1 is preferably 30 nm or less, more preferably 20 nm or less.

[0099] Furthermore, the test samples used for analyzing the Co-concentrated region 11 and the SB-concentrated region 12 are preferably fabricated using a microsampling method employing FIB (Focused Ion Beam). For example, to protect the surface during processing, a Pt film with a thickness of approximately 30 nm is formed on the outermost surface 10 of the soft magnetic alloy 1 by sputtering. Then, a section approximately 2 μm deep from the outermost surface is cut using FIB to obtain a thin sheet sample. This thin sheet sample is then processed to reduce the thickness in the direction orthogonal to the depth direction to less than 20 nm. This thin-film sample can then be used as a test sample for TEM or HRTEM observation.

[0100] The manufacturing method of the soft magnetic alloy 1 of this embodiment will be described below.

[0101] The matrix portion (internal region 2) of the soft magnetic alloy 1 can be manufactured by various melting methods, and is particularly preferably manufactured by quenching molten metal (molten metal). This is because quenching readily yields an amorphous soft magnetic alloy 1. For example, a strip-shaped soft magnetic alloy 1 can be manufactured by a single-roll method, and a powder-shaped soft magnetic alloy 1 can be manufactured by an atomization method. Hereinafter, methods for obtaining soft magnetic alloy strips by a single-roll method and methods for obtaining soft magnetic alloy powder by gas atomization, as an example of an atomization method, will be described.

[0102] In the single-roller process, firstly, raw materials (pure metals, etc.) constituting the soft magnetic alloy 1 are prepared and weighed in a manner that achieves the desired alloy composition. Then, the raw materials of each element are dissolved to produce a master alloy. The dissolution method for producing the master alloy is not particularly limited; for example, it can be achieved by high-frequency heating within a chamber with a specified vacuum level.

[0103] Next, the aforementioned master alloy is heated to melt it, yielding molten metal. The temperature of the molten metal can be set by considering the melting point of the target alloy composition, for example, it can be set to 1200–1600°C. In the single-roll method, the molten metal is supplied to a cooled rotating roll using a nozzle or the like, and a thin strip of soft magnetic alloy can be manufactured in the direction of the roll's rotation. At this time, the thickness of the obtained strip can be adjusted by controlling the roll's rotational speed, the distance between the nozzle and the roll, and the temperature of the molten metal. In addition, the temperature or rotational speed of the roll can be set to conditions that make the soft magnetic alloy easily become amorphous; for example, the roll temperature is preferably 20–30°C, and the rotational speed is preferably set to 20–30 m / sec. Furthermore, the atmosphere in the chamber is not particularly limited; for example, it can be set to an atmospheric atmosphere or an inert gas atmosphere.

[0104] In the gas atomization method, molten metal at 1200–1600°C is obtained similarly to the single-roller method described above. This molten metal is then sprayed into a chamber to produce powder. Specifically, molten metal is sprayed from the nozzle into the cooling section within the chamber, while high-pressure gas is injected into the sprayed molten metal. Through the injection of high-pressure gas, the molten metal is dispersed within the chamber and then collides with the cooling section (cooling water), where it is rapidly cooled and solidified into a soft magnetic alloy powder.

[0105] As the high-pressure gas, inert gases such as nitrogen, argon, and helium, or reducing gases such as ammonia decomposition gases, are preferably used. The pressure of the injected high-pressure gas is preferably set to 2.0 MPa or higher and 10 MPa or lower. Furthermore, the injection rate of the ejected molten metal is preferably set to 0.5 kg / min or higher and 4.0 kg / min or lower. In this gas atomization method, the particle size and shape of the soft magnetic alloy powder can be adjusted according to the ratio of the high-pressure gas pressure to the injection rate of the molten metal. The soft magnetic alloy powder obtained by this gas atomization method is generally spherical, and the average sphericity of the soft magnetic alloy powder is preferably 0.8 or higher, more preferably 0.9 or higher, and even more preferably 0.95 or higher.

[0106] After obtaining the soft magnetic alloy in the form of a thin strip or powder as described above, the soft magnetic alloy is heat-treated at low temperature in an oxygen concentration atmosphere under a specified pressure state, thereby forming the Co enrichment region 11 and the SB enrichment region 12.

[0107] Specifically, the holding temperature during heat treatment is preferably set to a temperature at which the soft magnetic alloy does not crystallize, for example, preferably 200°C to 400°C, more preferably 200°C to 300°C. Furthermore, the holding time is preferably set to 0.5 hours to 3.0 hours. The oxygen concentration in the heating furnace is preferably set to 20 ppm or more and 2000 ppm or less, more preferably 100 ppm or more and 1000 ppm or less. Additionally, in the heating furnace, the oxygen concentration is preferably managed as described above, and an inert gas such as argon or nitrogen is introduced and the pressure is set to positive pressure. The gauge pressure in the heating furnace is preferably set to 0.05 kPa or more and 0.50 kPa or less, more preferably 0.15 kPa or more and 0.45 kPa or less. Furthermore, gauge pressure refers to absolute pressure (pressure when absolute vacuum is set to 0 Pa) minus atmospheric pressure.

[0108] By performing heat treatment under these conditions, Co-enriched regions 11 and SB-enriched regions 12 with defined characteristics can be formed on the surface side of the soft magnetic alloy. Furthermore, depending on the heat treatment conditions, an Fe-containing oxide layer 13 may sometimes be formed on the surface side of the SB-enriched region 12. Additionally, when the soft magnetic alloy 1 is made crystalline or nanocrystalline (i.e., when the degree of amorphization X is set to less than 85%), a pre-process heat treatment for controlling crystallinity may be performed before performing the heat treatment for forming the aforementioned enriched regions.

[0109] exist Figure 4A and Figure 4B When the cladding layer 20 is formed as shown, it is sufficient to perform coating formation treatments such as phosphate treatment, mechanical alloying treatment, silane coupling treatment, and hydrothermal synthesis after the aforementioned heat treatment. Examples of types of cladding layer 20 include: phosphates, silicates, soda-lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, and sulfate glass. Furthermore, examples of phosphates include: magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium oxyphosphate; examples of silicates include: sodium silicate. When the cladding layer 20 is formed, an improvement in voltage withstand capability can be expected in the magnetic core containing the soft magnetic alloy 1.

[0110] Through the above processes, a soft magnetic alloy 1 having a Co-enriched region 11 and an SB-enriched region 12 can be obtained. The soft magnetic alloy 1 of this embodiment is applicable to various magnetic components such as coil components of inductors, filters, and antennas, and is particularly preferred for magnetic cores in coil components such as inductors. Furthermore, the soft magnetic alloy 1 can be constructed by mixing alloy compositions and particle groups with different particle sizes, or by mixing in other magnetic materials that do not have the enriched regions 11 and 12. For example, a magnetic core containing the soft magnetic alloy 1 may contain magnetic materials that do not have the enriched regions 11 and 12, or it may contain resin components.

[0111] (Summary of Implementation Methods)

[0112] In the soft magnetic alloy 1 of this embodiment, a Co-enriched region 11 and a Co-enriched region 12 with defined characteristics are formed on the outer side of the internal region 2, which is composed of a soft magnetic alloy containing Fe and Co. These characteristics suppress rusting of the soft magnetic alloy 1 when immersed in water, thus improving its corrosion resistance. In particular, by setting the Co concentration in the Co-enriched region 11 to be greater than 1.20, the corrosion resistance of the soft magnetic alloy 1 can be further improved.

[0113] Furthermore, by forming a Co-enriched region 11 and an SB-enriched region 12 in an amorphous soft magnetic alloy 1 with an amorphization degree of 85% or more, a high saturation magnetic flux density Bs can be ensured, and the corrosion resistance of the soft magnetic alloy 1 can be further improved.

[0114] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made within the scope of the present invention.

[0115] Example

[0116] The present invention will now be described in more detail based on specific embodiments. However, the present invention is not limited to the following embodiments. Furthermore, in the tables shown below, sample numbers marked with ※ are comparative examples.

[0117] Experiment 1

[0118] In Experiment 1, soft magnetic alloy powder was prepared by gas atomization. The gas atomization settings were: molten metal injection temperature: 1500℃, molten metal injection rate: 1.2 kg / min, high-pressure gas pressure: 7.0 MPa, and cooling water pressure: 10 MPa. This yielded soft magnetic alloy powder with an average particle size (D50) ranging from 15 to 30 μm on a volume basis. The soft magnetic alloy powder was then heat-treated under the conditions shown in Table 1 to obtain samples 2 to 11. Additionally, in Experiment 1, a sample 1 without heat treatment was also prepared, and the following evaluation was performed using sample 1 as a reference.

[0119] <Composition and Crystal Structure of Soft Magnetic Alloy Powder>

[0120] The composition of the soft magnetic alloy powder obtained by gas atomization was determined by ICP. The results confirmed that in all samples of Experiment 1, the soft magnetic alloy powder (i.e., internal region 2) had a composition satisfying the formula: (Fe... 0.7 Co 0.3 ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 The alloy composition is as follows: (atomic ratio; α = 0.300, β = 0, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010). Furthermore, X-ray crystal structure analysis of the soft magnetic alloy powder in Experiment 1 confirmed that in all samples of Experiment 1, the soft magnetic alloy powder (i.e., internal region 2) is amorphous with a degree of amorphization X: greater than 85%.

[0121] <Analysis of Surface Tissue>

[0122] For the soft magnetic alloys of each sample in Experiment 1, thin sheet samples were taken near the surface using the FIB microsampling method. These thin sheet samples were then analyzed by TEM-EDX to investigate the presence of Co-enriched region 11 and SB-enriched region 12. Compositional analysis was then performed in specific regions using TEM-EELS, and the Co concentration in Co-enriched region 11 was determined. The analytical results for each sample in Experiment 1 are shown in Table 1. Furthermore, for samples where Co-enriched region 11 or SB-enriched region 12 could be identified, HRTEM observation was also performed to confirm the phase state of each region. As a result, in the samples (samples 3–8, 10, and 11) where Co-enriched region 11 could be identified in Experiment 1, Co-enriched region 11 was an amorphous metallic phase, and SB-enriched region 12 was an amorphous oxide phase.

[0123] <Saturation magnetic flux density Bs>

[0124] The biomagnetic strength (Bs) of the soft magnetic alloys in each sample was measured using a vibrating sample magnetometer (VSM) under a magnetic field of 1000 kA / m. The results are shown in Table 1. For this Bs, values ​​above 1.50 T were considered good, and values ​​above 1.70 T were considered even better.

[0125] <Immersion Test>

[0126] First, before conducting the immersion test, magnetic core samples were fabricated using the soft magnetic alloy of each specimen. The magnetic core samples were fabricated in the following order: 100 parts by weight of the soft magnetic alloy were mixed with 3 parts by weight of epoxy resin to obtain granules. These granules were then filled into a mold at a rate of 4 tons / cm³. 2 The pressure was applied to form a ring-shaped magnetic core sample with an outer diameter of 11 mmφ, an inner diameter of 6.5 mmφ, and a height of 1.0 mm.

[0127] To evaluate the corrosion resistance of the obtained magnetic core samples, an immersion test was conducted. In the immersion test, the magnetic core samples were immersed in tap water, and the time until rust was visually observable (rust formation time) was measured. In Experiment 1, the corrosion resistance of each sample was evaluated based on the rust formation time T1 of sample 1 (which did not undergo heat treatment). Specifically, in Experiment 1, samples with a rust formation time less than 1.0 times T1 (rust formation time of sample 1) were designated "NG (Unacceptable)", samples with a rust formation time greater than 1.0 times but less than 1.2 times T1 were designated "G (Good)", and samples with a rust formation time greater than 1.2 times T1 were designated "VG (Exceptionally Good)". The results of the above three levels of evaluation ("NG", "G", and "VG") are shown in Table 1.

[0128] [Table 1]

[0129]

[0130] As shown in Table 1, in samples 3-8, 10, and 11 that underwent heat treatment under specified conditions, it was confirmed that Co-enriched regions 11 and SB-enriched regions 12 were formed. Furthermore, in these samples, high Bs levels were maintained, and the relative corrosion resistance compared to the reference alloy (sample 1, which did not undergo the specified heat treatment) was good. In addition, in samples 3-8, 10, and 11, the vertical distance d1 from the outermost surface 10 to the Co-enriched region 11 was less than 30 nm. Based on these results, it can be confirmed that corrosion resistance is improved by forming Co-enriched regions 11 and SB-enriched regions 12 with specified characteristics on the surface side of the soft magnetic alloy.

[0131] Furthermore, based on the results shown in Table 1, it can be confirmed that the Co concentration in the Co concentration region 11 is preferably greater than 1.02, and more preferably greater than 1.2.

[0132] Experiment 2

[0133] In Experiment 2, the alloy composition was changed to obtain soft magnetic alloys of samples 12 to 101. The alloy compositions of each sample analyzed by ICP are shown in Tables 2 to 7 (partially including the evaluation results of Experiment 1).

[0134] Specifically, among samples 12-25 shown in Table 2, those satisfying the composition formula: (Fe 1-α Co α ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 Based on the atomic ratios (β=0, γ=0, a=0.110, b=0, c=0.030, d=0.010, e=0.010), the atomic ratio α of Co was changed to produce a soft magnetic alloy. Furthermore, sample 18 is identical to sample 1 in Table 1, and sample 19 is identical to sample 5 in Table 1.

[0135] In addition, among the samples 26 to 45 shown in Table 3, soft magnetic alloys were produced by changing the atomic ratios of non-metals (B, P, Si, C) and Cr while keeping the atomic ratios of Co, Ni, and X1 fixed at α = 0.300, β = 0, and γ = 0.

[0136] In addition, among samples 46-49 shown in Table 4, those satisfying the composition formula: (Fe (1-(0.3+β) Co 0.3 Ni β ) 0.84B 0.11 Si 0.03 C 0.01 Cr 0.01 Based on the atomic ratios (α=0.300, γ=0, a=0.110, b=0, c=0.030, d=0.010, e=0.010), the atomic ratio β of Ni was changed, thereby creating a soft magnetic alloy.

[0137] In addition, among samples 50 to 101 shown in Tables 5 to 7, those satisfying the composition formula ((Fe 0.7 Co 0.3 ) 0.975 X1 0.025 ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 Based on the atomic ratio (α=0.300, β=0, γ=0.025, a=0.110, b=0, c=0.030, d=0.010, e=0.010), the types of elements in X1 were changed, thereby creating a soft magnetic alloy.

[0138] Furthermore, it was confirmed that the degree of amorphization X of each soft magnetic alloy in Experiment 2 was above 85%. In Experiment 2, for each alloy composition, samples subjected to the prescribed heat treatment and samples without heat treatment were prepared. In Tables 2 to 7, the cases with heat treatment are recorded as "Y", and the cases without heat treatment are recorded as "N". The heat treatment conditions for Experiment 2 were set as follows: holding temperature: 200°C, holding time: 1 h, oxygen concentration in the furnace: 100 ppm, and gauge pressure in the furnace: 0.3 kPa.

[0139] In addition, in each of the samples 12 to 101 of Experiment 2, the Bs content and water immersion test were performed in the same manner as in Experiment 1. In the water immersion test of Experiment 2, the rust formation time T of the samples that were not heat-treated with the same composition was used as the reference. N As a benchmark, the rust formation time of the heat-treated specimen was set as T. Y , will T Y / T N Samples with a value ≤1.0 are judged as "NG (non-compliant)," and samples with a value 1.0 <T are judged as "NG (non-compliant)." Y / T N Samples with a value < 1.2 are judged as "G (good)" and samples with a value 1.2 ≤ T are judged as "G (good)". Y / T N The samples were judged as "VG (Very Good)". The evaluation results are shown in Tables 2 to 7.

[0140] [Table 2]

[0141]

[0142] [Table 3]

[0143]

[0144] [Table 4]

[0145]

[0146] [Table 5]

[0147]

[0148] [Table 6]

[0149]

[0150] [Table 7]

[0151]

[0152] As shown in Tables 2 to 7, the specimens subjected to the specified heat treatment exhibited higher corrosion resistance than those without heat treatment. Based on these results, it can be concluded that by forming Co-enriched region 11 and SB-enriched region 12 within the alloy composition range shown in Experiment 2, high Bs levels can be maintained and corrosion resistance improved.

[0153] Furthermore, when supplementing the results in Table 2, a higher Co content in internal region 2 (i.e., the Co content of the soft magnetic alloy) tends to result in a longer rust formation time. That is, a higher Co content in internal region 2 generally indicates higher corrosion resistance as an absolute evaluation. However, as shown in sample 25 of Table 2, a higher Co content in internal region 2 tends to lead to a lower Co concentration. Moreover, regarding the relative improvement in corrosion resistance (i.e., corrosion resistance relative to the reference alloy), samples 13, 15, 17, 19, 21, and 23, with higher Co concentrations, show better results compared to sample 25. In other words, this result confirms that a higher Co concentration tends to further improve corrosion resistance relative to the reference alloy (samples that do not undergo heat treatment to form the concentration region).

[0154] Experiment 3

[0155] In Experiment 3, amorphous soft magnetic alloy powders with an amorphization degree X of 85% or higher (samples 1 and 5), nanocrystalline soft magnetic alloy powders with an amorphization degree X of less than 85% (samples 102 and 103), and crystalline soft magnetic alloy powders with an amorphization degree X of less than 85% (samples 104 and 105) were manufactured, and the influence of different crystal structures of soft magnetic alloys on corrosion resistance was investigated.

[0156] In Experiment 3, the crystal structure of each sample was controlled by a pre-process heat treatment. Specifically, samples 1 and 5 in Experiment 3 were not subjected to pre-process heat treatment, thus yielding amorphous soft magnetic alloy powder. Samples 102 and 103 in Experiment 3 underwent pre-process heat treatment at a holding temperature of 500°C for 10 minutes, resulting in nanocrystalline soft magnetic alloy powder. Samples 104 and 105 in Experiment 3 underwent pre-process heat treatment at a holding temperature of 650°C for 1 hour, resulting in crystalline soft magnetic alloy powder. Furthermore, other conditions in the above pre-process heat treatment were set as follows: heating rate of 100°C / min, furnace atmosphere of Ar, and gauge pressure in the furnace of 0.0 kPa, controlling the crystal structure without forming a Co concentration zone.

[0157] The composition of the soft magnetic alloy in each sample of Experiment 3 was (Fe) 0.7 Co 0.3 ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 Furthermore, in Experiment 3, samples were prepared according to each crystal structure, including those subjected to heat treatment to form each enriched region (11, 12) and those not subjected to heat treatment. In Table 8, the cases where heat treatment was performed are recorded as "Y", and the cases where heat treatment was not performed are recorded as "N". In addition, in the samples (103, 105) that underwent the previous heat treatment, the heat treatment to form each enriched region was performed after the previous heat treatment. In addition, the conditions for this heat treatment in Experiment 3 were set as follows: holding temperature: 200°C, holding time: 1 h, oxygen concentration in the furnace: 100 ppm, and gauge pressure in the furnace: 0.3 kPa.

[0158] In addition, in Experiment 3, the Bs content and immersion test were performed in the same manner as in Experiment 2. In the immersion test of Experiment 3, within the same crystal structure, the rust formation time T of the untreated sample was used as the reference. N As a benchmark, the rust formation time of the heat-treated specimen was set as T. Y , will T Y / T N Samples with a value ≤1.0 are judged as "NG (Not Acceptable)", and samples with a value 1.0 <T are judged as "NG (Not Acceptable)". Y / T N Samples with a value < 1.2 are judged as "G (good)" and samples with a value 1.2 ≤ T are judged as "G (good)". Y / T NThe sample was judged as "VG (Very Good)". The evaluation results of Experiment 3 are shown in Table 8.

[0159] [Table 8]

[0160]

[0161] As shown in Table 8, even in nanocrystalline or crystalline soft magnetic alloys, similar to the amorphous case, the corrosion resistance of samples 103 and 105, which underwent specified heat treatment to form Co-enriched region 11 and SB-enriched region 12, was improved compared to samples 102 and 104, which were not subjected to heat treatment. Furthermore, comparing the results of samples 102–105 with those of samples 1 and 5 in Table 8 shows that the improvement in corrosion resistance is particularly good when the soft magnetic alloy is amorphous.

[0162] Experiment 4

[0163] In Experiment 4, thin strip-shaped soft magnetic alloy samples (samples 106 and 107) were fabricated using the single-roller method. The fabrication conditions were set as follows: molten metal temperature sprayed onto the roll: 1300℃; roll temperature: 30℃; roll speed: 25 m / sec. Additionally, the chamber was set to an atmospheric atmosphere. The resulting soft magnetic alloy strips had a thickness of 20–25 μm, a width of approximately 5 mm along the short side, and a length of approximately 10 m.

[0164] In addition, in Experiment 4, the alloy composition of samples 106 and 107 was determined by ICP, similar to that in Experiment 1. The results confirmed that both samples met the composition formula: (Fe 0.7 Co 0.3 ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 (Atomic ratio; α = 0.300, β = 0, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010). Furthermore, XRD analysis of the crystal structure of the soft magnetic alloy ribbons in samples 106 and 107 confirmed that they were both amorphous with a degree of amorphization X: ≥ 85%.

[0165] For the soft magnetic alloy strip of sample 106, no heat treatment was performed, but surface microstructure analysis, Bs determination, and immersion test were conducted. On the other hand, for the soft magnetic alloy strip of sample 107, heat treatment was performed under the conditions shown in Table 9, and then the same evaluation as for sample 106 was conducted. Furthermore, in the immersion test of the soft magnetic alloy strip, test samples were prepared by cutting the strip into arbitrary sizes (approximately 4 cm in length × approximately 5 mm in width), and the strip-shaped test samples were immersed in tap water. The method for determining suitability in Experiment 4 was the same as in Experiment 1. The evaluation results of each sample in Experiment 4 are shown in Table 9. In addition, Table 9 also shows the experimental results of soft magnetic alloy powder with the same alloy composition as samples 106 and 107 (samples 1 and 5 of Experiment 1).

[0166] [Table 9]

[0167]

[0168] As shown in Table 9, it can be confirmed that even when the soft magnetic alloy has a thin strip shape, the Co enrichment region 11 and the SB enrichment region 12 are formed by the specified heat treatment, thereby maintaining high Bs and improving corrosion resistance.

Claims

1. A soft magnetic alloy, wherein, have: The internal region is composed of a soft magnetic alloy containing Fe and Co; The Co-concentrated region exists closer to the surface than the inner region, and the Co concentration is higher in the inner region. as well as The SB enrichment region is in contact with the surface of the Co enrichment region, and the concentration of at least one element selected from Si and B is higher than that of the inner region. The Co-concentrated region is a metallic phase. The alloy composition is based on the formula ((Fe) (1-(α+β)) Co α Ni β ) 1-γ X1 γ ) (1-(a+b+c+d+e)) B a P b Si c C d Cr e express, X1 is one or more elements selected from Ti, Zr, Hf, Nb, Ta, Mo, W, Al, Ga, Ag, Zn, S, Ca, Mg, V, Sn, As, Sb, Bi, N, O, Au, Cu, rare earth elements, and platinum group elements. The constituent α, β, γ, a, b, c, d, e satisfy the following requirements: 0.005≤α≤0.700， 0≤β≤0.200， 0 ≤ γ < 0.030, 0≤a≤0.200， 0≤b≤0.100， 0≤c≤0.150， 0≤d≤0.050， 0≤e≤0.050， 0.720≤(1-(a+b+c+d+e))≤0.

950.

2. The soft magnetic alloy according to claim 1, wherein, The SB enrichment region is an oxide phase.

3. The soft magnetic alloy according to claim 1 or 2, wherein, The SB enrichment region is amorphous.

4. The soft magnetic alloy according to claim 1 or 2, wherein, The Co concentration in the Co concentration region is greater than 1.

2.

5. The soft magnetic alloy according to claim 1 or 2, wherein, The degree of amorphization is above 85%.

6. The soft magnetic alloy according to claim 1 or 2, wherein, The soft magnetic alloy has a thin strip shape.

7. The soft magnetic alloy according to claim 1 or 2, wherein, The soft magnetic alloy is in powder form.

8. A magnetic component, wherein, The magnetic component comprises a soft magnetic alloy as described in any one of claims 1 to 7.

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