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; 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; and a Fe concentration region present closer to the surface side than the SB concentration region and containing Fe. In the soft magnetic alloy, a crystallization area ratio of the SB concentration region is set to S SB cry / S SB a crystallization area ratio of the Fe concentration region is set to S Fe cry / S Fe , (S SB cry / S SB ) < (S Fe cry / S Fe ).

Description

TECHNICAL FIELD

[0001] The present application relates to a soft magnetic alloy, and a magnetic component using the same. BACKGROUND

[0002] As a magnetic material used in various magnetic components such as an inductor, a soft magnetic alloy such as that shown in Patent Documents 1 to 3 is known. These soft magnetic alloys have a higher saturation magnetic flux density Bs than ferrite materials, and have good soft magnetic characteristics. However, the soft magnetic alloys sometimes corrode due to a storage state or a use environment, and improvement in corrosion resistance is required.

[0003] PRIOR ART 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

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] The present application was developed in view of the above-described circumstances, and aims to provide a soft magnetic alloy having high corrosion resistance, and a magnetic component using the same.

[0010] MEANS OF SOLVING THE PROBLEMS

[0011] To achieve the above-described object, the present application provides a soft magnetic alloy having:

[0012] an inner region having a soft magnetic alloy composition containing Fe and Co;

[0013] a Co concentration region existing closer to a surface side than the inner region, and having a higher concentration of Co than the inner region;

[0014] an SB concentration region existing 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; and

[0015] a Fe concentration region existing closer to the surface side than the SB concentration region, and containing Fe,

[0016] a crystallization area ratio of the SB concentration region is set to S SB cry / SSB and the crystallization area ratio of the Fe-enriched region is S Fe cry / S Fe (S SB cry / S SB ) < (S Fe cry / S Fe ).

[0017] The present inventors have conducted intensive studies, and as a result, have found that in the soft magnetic alloy having the above-described characteristics, rust during immersion in water is suppressed, and corrosion resistance is improved.

[0018] Preferably, the SB-enriched region is an amorphous oxide phase.

[0019] Preferably, the Co-enriched region is a metallic phase.

[0020] Preferably, the Co-enriched degree of the Co-enriched region is greater than 1.2.

[0021] Preferably, the amorphous degree of the soft magnetic alloy is 85% or more.

[0022] The soft magnetic alloy can have a thin strip shape, or can have a powder shape.

[0023] The use of the soft magnetic alloy of the present application is not particularly limited, and for example, can be applied to coil members such as inductors, various magnetic members such as filters, antennas, and the like. Even in the above-described uses, the soft magnetic alloy of the present application is suitable as a material for a magnetic core in coil members and the like. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a cross-sectional view that enlarges a main portion of the soft magnetic alloy 1 of one embodiment of the present application.

[0025] Figure 2A is an example of a graph obtained by X-ray crystal structure analysis.

[0026] Figure 2B is an example of a pattern obtained by profile fitting of the graph shown in FIG. 6. Figure 2A

[0027] Figure 3 is an example of a graph obtained by line analysis using EDX along the measurement line L M Figure 1

[0028] Figure 4A is a cross-sectional view that shows the soft magnetic alloy 1b of one embodiment of the present application.​​​

[0029] Figure 4B is an enlarged cross-sectional view of the region IVB shown in FIG. 1. Figure 4A

[0030] Figure 5A Figure 1

[0031] Figure 5B Figure 4A

[0032] Explanation of symbols

[0033] 1, 1b... Soft magnetic alloy

[0034] 2... Inner region

[0035] 10... Surface

[0036] 11... Co concentration region

[0037] 12... SB concentration region

[0038] 13... Fe concentration region

[0039] 20... Coating layerDETAILED DESCRIPTION

[0040] Hereinafter, the present application will be described in detail based on the embodiments shown in the drawings.

[0041] The soft magnetic alloy 1 of the present embodiment can have a thin strip shape, a powder shape, or another bulk shape, and the shape of the soft magnetic alloy 1 is not particularly limited. In addition, the size of the soft magnetic alloy 1 is also not particularly limited. For example, in the case where the soft magnetic alloy 1 is a thin strip shape, the thickness of the thin strip can be set to 15 μm to 100 μm, and in the case where the soft magnetic alloy 1 is a powder shape, the average particle diameter of the soft magnetic alloy powder can be set to 0.5 μm to 150 μm, and preferably 0.5 μm to 25 μm.

[0042] ​​​​​Further, the average particle diameter described above can be measured by various particle size analysis methods such as a laser diffraction method, but it is preferable to measure it using a particle image analyzer, Morphologi G3 (manufactured by Malvern Panalytical). In the Morphologi G3, the soft magnetic alloy powder is dispersed by air, and the projected area of the particles constituting the powder is measured, and the particle size distribution of the circle equivalent diameter is obtained from the projected area. Further, in the obtained particle size distribution, it is only necessary to calculate the average particle diameter as the particle diameter at which the cumulative relative number becomes 50% on a volume basis or on a number basis. Further, in the case where the soft magnetic alloy 1 is included in the magnetic core, it is only necessary to measure the circle equivalent diameter of the particles contained in the cross section by cross-sectional observation using an electron microscope (SEM, STEM, etc.), and thereby calculate the average particle diameter of the soft magnetic alloy 1 (powder).

[0043] Figure 1 is an enlarged cross-sectional view of the vicinity of the surface of the soft magnetic alloy 1. As shown in Figure 1 , the soft magnetic alloy 1 has an inner region 2, a Co concentration region 11 located closer to the surface side of the soft magnetic alloy 1 than the inner region 2, an SB concentration region 12 located closer to the surface side of the soft magnetic alloy 1 than the Co concentration region 11, and an Fe concentration region 13 located closer to the surface side of the soft magnetic alloy 1 than the SB concentration region 12. Further, in the present embodiment, the "inner side" refers to the side closer to the center of the soft magnetic alloy 1, and the "surface side" or "outer side" refers to the side farther from the center of the soft magnetic alloy 1.

[0044] (Inner Region 2)

[0045] The inner region 2 is a base portion of the soft magnetic alloy 1 occupying at least 90 vol% or more of the volume of the soft magnetic alloy 1. Therefore, the average composition of the soft magnetic alloy 1 can be regarded as the composition of the inner region 2, and the crystal structure of the soft magnetic alloy 1 can be regarded as the crystal structure of the inner region 2. Further, the volume ratio of the above-described inner region 2 can be replaced by an area ratio, and at least 90% or more of the cross-sectional area of the soft magnetic alloy 1 is the inner region 2.

[0046] 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 provided as a soft magnetic alloy of a crystal system of Fe-Co-based alloy or Fe-Co-V-based alloy, Fe-Co-Si-based alloy, Fe-Co-Si-Al-based alloy, or the like. It is preferable that P be further contained in the inner region 2, and as a soft magnetic alloy of a crystal system containing P, Fe-Co-Si-P-based alloy or Fe-Co-Si-P-Cr-based alloy, or the like can be cited. By containing P in the inner region 2, Co is easily concentrated at the outer edge of the inner region 2.

[0047] In addition, from the viewpoint of reducing the coercive force, the inner region 2 preferably has an amorphous or nanocrystalline alloy composition, and as an amorphous or nanocrystalline soft magnetic alloy, Fe-Co-P-C-based alloy, Fe-Co-B-based alloy, or Fe-Co-B-Si-based alloy, or the like can be cited. More specifically, the inner region 2 preferably has an alloy composition satisfying the composition 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 By having the above composition, an amorphous, heteroamorphous, or nanocrystalline crystal structure is easily obtained.

[0048] In the above composition formula, B is boron, P is phosphorus, C is 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. The rare earth elements include Sc, Y, and lanthanoids, and the platinum group elements include Ru, Rh, Pd, Os, Ir, and Pt. In addition, a, b, c, d, and e are atomic ratios, and these atomic ratios preferably satisfy the following requirements.

[0049] The content (a) of Co with respect to Fe is 0.005 ≤ a ≤ 0.700, can also be 0.010 ≤ a ≤ 0.600, can also be 0.030 ≤ a ≤ 0.600, and can also be 0.050 ≤ a ≤ 0.600. By a being within the above range, Bs and corrosion resistance are improved. From the viewpoint of improving Bs, it is preferable that 0.050 ≤ a ≤ 0.500. The greater a is, the more corrosion resistance tends to be improved, and in the case where a is excessively large, Bs is easily reduced.

[0050] In addition, the content of Ni relative to Fe (β) is 0 < β < 0.200. That is, Ni can not be contained, or 0.005 < β < 0.200. From the viewpoint of increasing Bs, 0 < β < 0.050, 0.001 < β < 0.050, or 0.005 < β < 0.010 can be used. The greater β is, the more the corrosion resistance tends to increase, but in the case where β is too great, Bs decreases.

[0051] X1 can also be contained as an impurity or can be intentionally added. The content of X1 (γ) is 0 < γ < 0.030. That is, X1 can be used to replace a portion of less than 3.0% of the total content of Fe, Co, and Ni.

[0052] In addition, when the sum of the atomic ratios of the respective elements that constitute 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, and more preferably 0.780 < (1 - (a + b + c + d + e)) < 0.890. By satisfying this requirement, Bs is easily increased. In addition, by being 0.720 < (1 - (a + b + c + d + e)) < 0.890, an amorphous state is easily obtained.

[0053] a is the atomic ratio of B, and is preferably 0 < a < 0.200, and more preferably 0 < a < 0.150 from the viewpoint of increasing Bs.

[0054] b is the atomic ratio of P, and is preferably 0 < b < 0.100. That is, P can not be contained, and from the viewpoint of balancing the increase in Bs and the corrosion resistance, more preferably 0.001 < b < 0.100, further preferably 0.005 < b < 0.080, and particularly preferably 0.005 < b < 0.050.

[0055] c is the atomic ratio of Si, and is preferably 0 < c < 0.150. That is, Si can not be contained, and from the viewpoint of balancing the increase in Bs and the corrosion resistance, more preferably 0.001 < c < 0.070.

[0056] d is the atomic ratio of C, and is preferably 0 < d < 0.050. That is, C can not be contained, and from the viewpoint of balancing the increase in Bs and the corrosion resistance, more preferably 0 < d < 0.020.

[0057] e is the atomic ratio of Cr, and is preferably 0 < e < 0.050. That is, from the viewpoint of increasing Bs, Cr can not be contained, and from the viewpoint of balancing the increase in Bs and the corrosion resistance, more preferably 0.001 < e < 0.020.

[0058] The composition of the internal region 2 (i.e., the composition of the soft magnetic alloy 1) described above can be analyzed using, for example, inductively coupled plasma emission spectroscopy (ICP). In this case, in the case where it is difficult to obtain the oxygen content by ICP, pulsed heating fusion extraction can be used in combination. In addition, in the case where it is difficult to obtain the carbon content and the sulfur content by ICP, infrared absorption can be used in combination.

[0059] In addition, composition analysis can be performed by EDX (energy dispersive X-ray analysis) or EPMA (electron probe microanalyzer) attached to an electron microscope, in addition to ICP. For example, in the case of the soft magnetic alloy 1 contained in a magnetic core having a resin component, it is sometimes difficult to perform composition analysis by ICP, in which case composition analysis can be performed using EDX or EPMA. In addition, in the case where detailed composition analysis is difficult by any of the above-described methods, composition analysis can be performed using 3DAP (three-dimensional atom probe). In the case of using 3DAP, the resin component and the effects of surface oxidation can be excluded, and the composition of the soft magnetic alloy 1, i.e., the internal region 2, can be measured in the region of analysis. This is because, in 3DAP, a small region (for example, a region of φ 20 nm x 100 nm) can be set in the interior of the soft magnetic alloy 1 and the average composition can be measured.

[0060] Further, in the case of performing line analysis on a 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 in which the concentration of Fe or the concentration of Co is stable (see FIG. 6). Figure 3 In addition, for example, the average composition of the internal region 2 obtained by mapping analysis can be set as the composition of the soft magnetic alloy 1. In this case, mapping analysis is performed using EDX or EELS, and the measurement site at this time is set to a region (corresponding to the internal region 2) of 100 nm or more in the depth direction from the surface of the soft magnetic alloy 1, and the measurement field of view is set to a range of 256 nm x 256 nm or more.

[0061] The crystal structure of the internal region 2 (i.e., the crystal structure of the soft magnetic alloy 1) can be crystalline, nanocrystalline, amorphous, and more preferably amorphous. In other words, the amorphous degree X of the internal region 2 (i.e., the amorphous degree X of the soft magnetic alloy 1) is preferably 85% or more. The crystal structure having an amorphous degree X of 85% or more is a structure substantially composed of amorphous, or a structure composed of heterogeneous amorphous. Here, the structure composed of heterogeneous amorphous refers to a structure in which crystals are present in a very small amount in amorphous. That is, in the present embodiment, the "crystal structure of amorphous" refers to a crystal structure having an amorphous degree X of 85% or more, and crystals can be included within the range satisfying the amorphous degree X.

[0062] 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 crystalline 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 crystalline structure with an amorphization degree X of less than 85% and an average crystal grain size of more than 100 nm.

[0063] The degree of amorphization, X, can be determined by X-ray crystallographic analysis using XRD. Specifically, the soft magnetic alloy 1 of this embodiment is subjected to 2θ / θ measurement by XRD to obtain... Figure 2A The diagram is as shown. 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°.

[0064] 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 obtained 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+a Furthermore, 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).

[0065] X=100-(Ic / (Ic+Ia)×100)……(1)

[0066] Ic: Integral intensity of crystalline scattering

[0067] Ia: Integral intensity of amorphous scattering

[0068]

[0069] h: Peak height

[0070] u: Peak position

[0071] w: half-width

[0072] b: Background height

[0073] Further, the method for measuring the amorphous degree X is not limited to the above-described method using XRD, and can be measured by EBSD (crystal orientation analysis) or electron beam diffraction.

[0074] (Co concentration region 11)

[0075] The Co concentration region 11 is a region in which the concentration of Co is higher than that of the above-described inner region 2. In the present embodiment, the Co concentration region 11 is preferably an amorphous metallic phase continuous from the inner region 2, covering at least a part of the outer periphery of the inner region 2. In the cross section of the soft magnetic alloy 1, the coverage ratio of the Co concentration region 11 with respect to the inner region 2 is not particularly limited, and can be set to 50% or more, and more preferably 80% or more.

[0076] Whether or not the Co concentration region 11 exists and the coverage ratio thereof can be confirmed by observing the cross section of the soft magnetic alloy 1 near the surface using STEM (scanning transmission electron microscope) or TEM (transmission electron microscope), and performing mapping analysis using EDX or EELS at that time. For example, Figure 5A The image (EELS image) shown is an example of the result of mapping analysis by EELS. Figure 5A The three EELS images of FIG. 3 are all results of measuring the same site, and the left EELS image (Co-L) indicates the distribution of Co, the central EELS image (B-K) indicates the distribution of B, and the right EELS image (Fe-L) indicates the distribution of Fe. In the EELS images, the inner region 2 can be recognized as a region in which there is almost no concentration difference in the concentration distribution of Fe and Co. Further, at the end edge of the inner region 2, the contrast indicating Co becomes bright (with reference to the EELS image of Co-L), and it is known that the Co concentration is higher than that of the inner region 2. This region in which the Co concentration is high is the Co concentration region 11, and the presence or absence of the Co concentration region 11 can be confirmed by the EELS image related to Co.

[0077] The average thickness t1 of the Co concentration region 11 specified by the mapping analysis is preferably 0.3 nm or more. The upper limit of t1 is not particularly limited, and can be set to 30.0 nm or less, for example. By thickening t1 within this appropriate range, a more favorable result with respect to corrosion resistance is obtained. Further, the average thickness t1 is preferably determined by measuring the thickness of the Co concentration region 11 at at least three sites or more and calculating.

[0078] As described above, the Co concentration region 11 is sometimes extremely thin in thickness, and when the Co concentration region 11 is specified, it is preferable to use not only mapping analysis but also line analysis. Figure 3 is an example of a measurement line L Figure 1 The measurement line L shown in FIG. 4 is a line parallel to the direction of the arrow of the soft magnetic alloy 1, and is a line extending in the direction of the arrow of the soft magnetic alloy 1. MA schematic diagram of the results of the line analysis is shown. The vertical axis represents the detection intensity of each element (i.e., the intensity of the characteristic X-rays), and the horizontal axis represents the distance (depth) from the outermost surface 10. As shown in Figure 3, 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. The location of this Co peak is the Co concentration region 11. In other words, the Co concentration maximum exists in the Co concentration region 11. The presence or absence of the aforementioned peak confirms the existence of the Co concentration region 11.

[0079] 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, for example, by the aforementioned line analysis, mapping analysis, or analysis using a STEM or an EELS (electron energy loss spectroscopy) detector attached to a TEM. Specifically, when the Co-enriched region 11 is a metallic phase, in line analysis or mapping analysis, the oxygen concentration in the Co-enriched region 11 becomes lower than the oxygen concentration in the SB-enriched region 12 described later (see reference). Figure 3 Furthermore, when analyzing the spectrum obtained from 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, observing the TEM image of the transmitted wave reveals a darker contrast compared to the SB-enriched region 12, which is an oxide phase, further confirming that the Co-enriched region 11 is a metallic phase.

[0080] 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 Co The 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.

[0081] 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 is 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.

[0082] C2 used to calculate Co concentration Co and C11 CoThe measurement is performed by composition analysis using EELS. Specifically, C2 Co is the mass fraction of Co detected in the internal region 2 with respect to the total of Fe and Co, and is calculated by analysis of the EELS spectrum. Also, C11 Co is the mass fraction of Co detected in the Co concentration region 11 with respect to the total of Fe and Co. That is, the mass fraction of Co in each region is expressed as Co / (Fe+Co), and in order to exclude the influence of impurities (elements mixed in when the measurement sample is produced, etc.), the denominator is set to (Fe+Co). Furthermore, the resolution in this analysis is preferably set to 0.5 nm or less, C2 Co measurement is preferably performed on at least 5 or more sites in the field of view, and the average value thereof is calculated.

[0083] Furthermore, in the Co concentration region 11, Co is detected as the main constituent element, and in addition thereto, elements such as Fe that constitute the internal region 2 are contained. Also, in the Co concentration region 11, concentration of other elements can also occur in addition to the concentration of Co, and as the other elements, for example, P can be cited. In this case, in the mapping analysis or the line analysis, a high concentration region of P can sometimes be observed in a manner repeated with the portion where the concentration of Co is high.

[0084] (SB concentration region 12)

[0085] The SB concentration region 12 is a region where the concentration of at least one element selected from Si and B is higher than that of the internal region 2, and in the SB concentration region 12, either one of Si or B can be concentrated, or both Si and B can be concentrated. In the present embodiment, this SB concentration region 12 covers at least a part of the outer periphery of the Co concentration region 11. Also, in a portion where the Co concentration region 11 is not present locally, the SB concentration region 12 sometimes directly borders on and covers the internal region 2. The coverage rate of the SB concentration region 12 in the soft magnetic alloy 1 is not particularly limited, and for example, it can be set to 50% or more, and more preferably 80% or more.

[0086] As with the Co concentration region 11, the presence or absence of the SB concentration region 12 can also be confirmed by mapping analysis using EDX or EELS. For example Figure 5A In the EELS image (B-K) of the center of FIG. 10, the concentration of B is expressed by the contrast of the brightness, and it can be confirmed that the concentration of B becomes higher than that of the internal region 2 on the surface side of the Co concentration region 11. In Figure 5A the case of FIG. 10, the region where the concentration of B is high is the SB concentration region 12.

[0087] The average thickness t2 of the SB concentration region 12 specified by the mapping analysis is preferably 0.5 nm or more. The upper limit of t2 is not particularly limited, and can be set to 30 nm or less, for example. Also, for the average thickness t2, as with t1, it is preferable to change the measurement field of view, measure the thickness of the SB concentration region 12 at at least three sites or more, and perform the calculation.

[0088] In addition, the SB concentration region 12 is preferably specified by both the mapping analysis and the line analysis. As shown in FIG. 6, in the line analysis result, a peak (a peak including a Si or / and B maximum value) of the concentration of Si or / and B can be confirmed on the surface side closer than the peak of Co, and the existence site of this peak is the SB concentration region 12. More specifically, it can be judged based on the intensity of the characteristic X-rays caused by Si and B at the time of the line analysis. That is, in the case where the intensity of the characteristic X-rays caused by Si and B with respect to the internal region 2 is higher in the SB concentration region 12, it can be judged that Si or / and B is concentrated. Also, as described above, in the mapping analysis, the content of each element can also be mapped from the intensity of each element, and thus the SB concentration region 12 can be identified based on the obtained mapping image. Figure 3

[0089] Regarding the SB concentration region 12, the degree of concentration of Si and B is expressed by the intensity ratio, which is calculated by the line analysis using EDX or EELS. Specifically, the detection intensity of Si in the SB concentration region 12 is set to C12 S , and the detection intensity of Si in the internal region 2 is set to C2 S , C12 S / C2 S is set to the Si intensity ratio (concentration degree) in the SB concentration region 12. From the viewpoint of resolution, the Si intensity ratio is preferably measured by EDX, and in the case where Si is concentrated in the SB concentration region 12, the Si intensity ratio exceeds 1.0. In the present embodiment mode, the Si intensity ratio is preferably 1.1 or more, and more preferably 1.2 or more. In addition, the upper limit of the Si intensity ratio is not particularly limited, and can be set to 20 or less, for example.

[0090] Similarly, the detection intensity of B in the SB concentration region is set to C12 B , and the detection intensity of B in the internal region 2 is set to C2 B , C12 B / C2 B ​The B intensity ratio (concentration degree) in the SB concentration region 12 is set. From the viewpoint of resolution, the B intensity ratio is preferably measured by EELS, and in the case where B is concentrated in the SB concentration region 12, the B intensity ratio exceeds 1.0. In the present embodiment, the B intensity ratio is preferably 1.1 or more, and more preferably 1.2 or more. In addition, the upper limit of the B intensity ratio is not particularly limited, and can be set to 20 or less, for example.

[0091] The SB concentration region 12 is preferably an oxide phase. In the case where the SB concentration region 12 is an oxide phase, it is possible to confirm in the mapping analysis described above that a high concentration region of oxygen and a high concentration region of Si or / and B repeatedly exist. In addition, in the line analysis result, the concentration of oxygen is higher than that in the inner region 2 or the Co concentration region 11 at the portion where a peak of Si or / and B exists. For example, FIG. 3 illustrates a case where a part of the peak of Si concentration and the peak of oxygen in the SB concentration region 12 repeatedly exist. Furthermore, in the case where the SB concentration region 12 is an oxide phase, in the TEM image, the SB concentration region 12 can be recognized as a region brighter than the inner region 2 in contrast. In addition, also for the SB concentration region 12, as with the Co concentration region 11, the phase state can be confirmed by analyzing (fitting) the spectrum obtained by EELS.

[0092] In addition, the SB concentration region 12 is preferably amorphous. Here, the crystallinity of the SB concentration region 12 is judged from the presence or absence of a spot caused by crystallization in the FFT (Fast Fourier Transform) pattern. That is, if no spot is confirmed in the FFT pattern of the SB concentration region 12, it is judged that the SB concentration region 12 is amorphous, and if a spot is confirmed, it is judged that it is crystalline. By observing the cross section including the SB concentration region 12 by HRTEM (High Resolution Transmission Electron Microscopy), the FFT pattern can be obtained by performing fast Fourier transform processing on the obtained HRTEM image. In addition, the crystal structure of the SB concentration region 12 can also be analyzed by a restricted field method or a nanobeam diffraction method in a small region.

[0093] Furthermore, in the case where the crystallinity of the SB concentration region 12 is amorphous in the method described above, a crystal is sometimes locally mixed in the inside of the SB concentration region 12. That is, even in the case where the SB concentration region 12 is set to be amorphous, a crystal can be contained to such a degree that no spot caused by crystallization is generated in the FFT pattern.

[0094] More specifically, the crystallization area ratio (S SB cry / S SBThe preferred value is 0 to 0.5. This crystallization area ratio can be determined by image analysis of HRTEM images. In HRTEM images, by using phase contrast, a regular lattice arrangement can be confirmed in the crystalline region, while an irregular random pattern can be confirmed in the amorphous region. Therefore, by performing image analysis on HRTEM images, the area S of the SB-concentrated region 12 contained within the measurement field of view can be determined. SB And the area S of the region where the regular lattice arrangement can be confirmed (i.e., the crystalline portion). SB cry As S SB cry Compared to S SB The ratio can be used to calculate the crystallization area.

[0095] In addition, in the SB enrichment region 12, as described above, Si, B, and O can be detected, as well as Fe and Co, which are constituent elements of the internal region 2.

[0096] (Fe concentration region 13)

[0097] The Fe-enriched region 13 is an oxide phase containing at least Fe, covering at least a portion of the outer periphery of the SB-enriched region 12. Additionally, in areas where the SB-enriched region 12 is not present, the Fe-enriched region 13 may be directly connected to the Co-enriched region 11 or the internal region 2. The coverage percentage of the Fe-enriched region 13 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.

[0098] The Fe concentration C13 in Fe concentration region 13 Fe Preferably, the Fe concentration is higher than that in other concentration regions (11, 12). For example, the Fe concentration C13 in Fe concentration region 13 is higher. Fe / C2 Fe It can be set to 1 < (C13) Fe / C2 Fe The concentration of Fe in each of the aforementioned regions (2, 11–13) can be determined using EELS or similar methods. Similar to the concentration of Co, it can be calculated as the molar ratio of Fe to the total amount of Fe and Co detected at the measurement point (i.e., Fe / (Fe+Co)). Furthermore, as with the concentrations of Co and SB, it is preferable to change the measurement field of view and perform component analysis using EELS or similar methods at at least five sites, and calculate the average value.

[0099] Like the other concentrated regions (11, 12), the presence of Fe-concentrated region 13 could be confirmed by mapping analysis using EDX or EELS. For example, Figure 5AIn the EELS image (Fe-L) on the left side, the detection intensity of Fe in the SB concentration region 12 in which the detection intensity of Si or / and B is high is confirmed to be lower than that in the inner region 2. Also, in the case where the Fe concentration region 13 exists, a region in which the detection intensity of Fe is high exists in a manner of covering the region (SB concentration region 12) in which the intensity of Fe is low, and Fe is concentrated outside the SB concentration region 12. In this way, the Fe concentration region 13 can be identified by mapping analysis.

[0100] The average thickness t3 of the specific Fe concentration region 13 by the above-described method is preferably 1 nm or more. The upper limit of t3 is not particularly limited, and can be set to 50 nm or less, for example. The average thickness t3 of the Fe concentration region 13 is also preferably changed in the measurement field of view, and the thickness of the Fe concentration region 13 is measured at at least three or more sites and calculated.

[0101] In addition, the presence or absence of the Fe concentration region 13 can be confirmed not only by mapping analysis but also by line analysis. In the case where the Fe concentration region 13 exists, the Fe concentration region 13 can be confirmed by the line analysis result shown in FIG. 6. Figure 3 In the line analysis result shown in FIG. 6, a peak in which the detection intensity of Fe in the Fe concentration region 13 is higher than that in the SB concentration region 12 exists, and based on the Fe peak, it can be confirmed that Fe is concentrated outside the SB concentration region 12. In addition, as described above, the Fe concentration region 13 is an oxide phase, and thus, when the Fe concentration region 13 is analyzed by mapping analysis or line analysis, it can be confirmed that the concentration of oxygen exists at a higher concentration than that in the inner region 2. In addition, when the spectrum obtained by EELS is analyzed, the proportion of oxide Fe and metallic Fe in the Fe concentration region 13 can be calculated, and in the case where the proportion of oxide Fe is higher than that of metallic Fe, the Fe concentration region 13 is defined as an oxide phase. In this way, as long as the presence or absence or the phase state of the Fe concentration region 13 is analyzed by mapping analysis, line analysis, or spectrum analysis of EELS, or the like.

[0102] The crystal structure of the Fe concentration region 13 is a structure including crystallinity, and a spot caused by crystallization can be confirmed in the FFT pattern of the Fe concentration region 13. In addition, as with the SB concentration region 12, when the crystallization area ratio (S Fe cry / S Fe ) in the cross section of the Fe concentration region 13 is measured by image analysis of the HRTEM image, S Fe cry / S Fe is higher than that of the SB concentration region 12, and satisfies (S SB cry / S SB . SB cry / S SB )<(S Fe cry / S Fe ). In other words, the Fe concentration region 13 and the SB concentration region 12 are represented by "(S Fe cry / S Fe )-(S SB cry / S SB )" and the difference DCA in the crystallization area ratio is 0 < DCA. By forming the Fe concentration region 13 having such a crystalline structure outside the SB concentration region 12, the corrosion resistance of the soft magnetic alloy 1 is improved.

[0103] crystallization area ratio S Fe cry / S Fe The specific numerical range of the difference "(S Fe cry / S Fe )-(S SB cry / S SB )" is not particularly limited, and is preferably 0.01 or more, and more preferably 0.05 or more. In addition, for the crystalline structure of the Fe concentration region 13, in addition to the analysis method using the HRTEM described above, a restricted field method or a nanobeam diffraction method in a small region can be used for analysis.

[0104] In the Fe concentration region 13 having the above-described characteristics, at least Fe and O can be detected, and in addition, Co, Si, B, P, and the like, which are the constituent elements of the inner region 2, can be detected. However, the Co concentration in the Fe concentration region 13 is lower than the Co concentration in the inner region 2 or the Co concentration region 11, and the total concentration of Si and B in the Fe concentration region 13 is lower than the inner region 2 and the SB concentration region 12.

[0105] As described above, the soft magnetic alloy 1 has a characteristic surface structure including the Co concentration region 11, the SB concentration region 12, and the Fe concentration region 13. In particular, in the present embodiment, as shown in FIG. 1, the Fe concentration region 13 is located at the most surface side and constitutes the most surface 10 of the soft magnetic alloy 1. However, as shown in the soft magnetic alloy 1b of FIG. 2, an insulating coating layer 20 can be formed outside the Fe concentration region 13. Figure 1 Figure 4A Figure 4B In this case, the most surface 10 of the soft magnetic alloy 1b is constituted by the coating layer 20. In fact,

[0106] In this case, the most surface 10 of the soft magnetic alloy 1b is constituted by the coating layer 20. In fact, Figure 5B Figure 4A ​​​An example of a STEM image of the soft magnetic alloy 1b is shown. In the STEM image, a region with a bright contrast can be confirmed at the surface of the soft magnetic alloy 1b, and this region is the coating layer 20. The coating layer 20 is a film formed by surface treatment such as coating after the formation of the respective concentration regions (11 to 13), and the average thickness thereof is preferably 5 nm or more and 100 nm or less, and more preferably 50 nm or less. Further, as shown in the figure, such a coating layer 20 is formed in a soft magnetic alloy in a powder shape, and can also be formed in a soft magnetic alloy in a thin strip shape. Figure 4A

[0107] Thus, the coating layer 20 or the like can be contained in the surface layer structure of the soft magnetic alloy 1, but even in the case where the coating layer 20 is present, the Co concentration region 11 is present on the side in contact with the inner region 2. Further, the perpendicular distance dl from the surface 10 to the Co concentration region 11 is preferably 200 nm or less, more preferably 100 nm or less, and further preferably 50 nm or less. In particular, in the case where the Fe concentration region 13 constitutes the surface 10 in the absence of the coating layer 20, the perpendicular distance dl is preferably 30 nm or less, and more preferably 20 nm or less.

[0108] Further, the measurement sample at the time of analyzing the respective concentration regions (11 to 13) is preferably produced by a microsampling method using an FIB (focused ion beam). For example, in order to protect the surface at the time of processing, a Pt film with a thickness of 30 nm or so is formed on the surface 10 of the soft magnetic alloy 1 by sputtering, and then a range with a depth of about 2 μm or so from the surface is cut out by an FIB, and a thin sample is obtained. Then, the thin sample is processed so as to be thinned to 20 nm or less in thickness in a direction orthogonal to the depth direction. This thinned sample can be used as a measurement sample for TEM or HRTEM observation.

[0109] Next, the method for producing the soft magnetic alloy 1 of the present embodiment will be described.

[0110] The base portion (inner region 2) of the soft magnetic alloy 1 can be produced by various dissolution methods, and is particularly preferably produced by a method in which a molten metal (metallic melt) is rapidly cooled. This is because an amorphous soft magnetic alloy 1 is easily obtained by rapid cooling. For example, a soft magnetic alloy 1 in a thin strip shape can be produced by a single roll method, and a soft magnetic alloy 1 in a powder shape can be produced by an atomization method. Hereinafter, a method for obtaining a soft magnetic alloy thin strip by a single roll method, and a method for obtaining a soft magnetic alloy powder by a gas atomization method as an example of the atomization method will be described.

[0111] ​In the single-roller method, first, raw materials (pure metals or the like) of each element constituting the soft magnetic alloy 1 are prepared and weighed so as to have the target alloy composition. Then, the raw materials of each element are dissolved to produce a master alloy. The method of dissolving at the time of producing the master alloy is not particularly limited, and for example, there is a method of dissolving by high-frequency heating in a chamber at a prescribed vacuum degree.

[0112] Next, the above master alloy is heated and dissolved to obtain molten metal. The temperature of the molten metal can be set as appropriate in consideration of the melting point of the target alloy composition, and for example, can be set to 1200 to 1600°C. In the single-roller method, the molten metal can be supplied to a cooled rotating roller by using a nozzle or the like, and a thin ribbon of the soft magnetic alloy can be produced toward the rotating direction of the roller. At this time, the thickness of the obtained thin ribbon can be adjusted by controlling the rotation speed of the roller, the interval between the nozzle and the roller, the temperature of the molten metal, and the like. In addition, the temperature or the rotation speed of the roller can be set as appropriate so that the soft magnetic alloy easily becomes amorphous, and for example, the roller temperature is preferably 20 to 30°C, and the rotation speed is preferably set to 20 to 30 m / sec. Furthermore, the atmosphere in the chamber is not particularly limited, and for example, can be set to an atmospheric atmosphere or an inert gas atmosphere.

[0113] In the gas atomization method, as in the above single-roller method, after obtaining molten metal at 1200 to 1600°C, the molten metal is sprayed in a chamber to produce a powder. Specifically, the molten metal is sprayed from a spray outlet to a cooling portion in the chamber, at which time high-pressure gas is sprayed toward the sprayed droplet molten metal. By the spraying of the high-pressure gas, the droplet molten metal scatters in the chamber, and then collides with the cooling portion (cooling water), whereby it is rapidly solidified to become a soft magnetic alloy powder. The particle shape of the soft magnetic alloy powder obtained by the gas atomization method is generally spherical, and the average circularity of the soft magnetic alloy powder is preferably 0.8 or more, more preferably 0.9 or more, and further preferably 0.95 or more.

[0114] As the high-pressure gas, an inert gas such as nitrogen, argon, or helium, or a reducing gas such as ammonia decomposition gas is preferably used, and the pressure of the sprayed high-pressure gas is preferably set to 2.0 MPa or more and 10 MPa or less. In addition, the spraying amount of the sprayed molten metal is preferably set to 0.5 kg / min or more and 4.0 kg / min or less. In the gas atomization method, the particle diameter or the shape of the soft magnetic alloy powder can be adjusted according to the ratio of the pressure of the high-pressure gas to the spraying amount of the molten metal.

[0115] After obtaining the soft magnetic alloy in the form of a thin ribbon or a powder as described above, the soft magnetic alloy is heat-treated at a low temperature in an oxygen concentration atmosphere at a prescribed pressure state, whereby each concentration region (11 to 13) is formed.

[0116] Specifically, the holding temperature at the time of heat treatment is preferably set to a temperature at which the soft magnetic alloy is not crystallized, for example, preferably 300°C to 400°C. In addition, the temperature holding time is preferably set to 0.25 hours to 3.0 hours, more preferably 1.0 hour to 1.5 hours. The oxygen concentration in the heating furnace is preferably set to 100 ppm or more and 2000 ppm or less, more preferably 300 ppm or more and 1000 ppm or less. In addition, 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 set to a positive pressure, and the gauge pressure in the heating furnace is set to 0.15 kPa or more and 0.50 kPa or less, more preferably 0.15 kPa or more and 0.45 kPa or less. In addition, the gauge pressure refers to the pressure obtained by subtracting the atmospheric pressure from the absolute pressure (the pressure when the absolute vacuum is set to 0 Pa).

[0117] By performing heat treatment under such conditions, the Co concentration region 11, the SB concentration region 12, and the Fe concentration region 13 having predetermined characteristics can be formed on the surface layer side of the soft magnetic alloy. In addition, in the case where the soft magnetic alloy 1 is crystallized or nanocrystallized (i.e., in the case where the amorphous degree X is set to be lower than 85%), a pre-process heat treatment for controlling the crystallinity can also be performed before the heat treatment for forming the above-described respective concentration regions is performed.

[0118] As shown in FIG. 1, the soft magnetic alloy 1 according to the present embodiment has a Co concentration region 11, an SB concentration region 12, and an Fe concentration region 13 on the surface layer side. The respective concentration regions 11 to 13 are formed by heat treatment. Figure 4A and Figure 4B As shown in FIG. 1, the soft magnetic alloy 1 according to the present embodiment has a Co concentration region 11, an SB concentration region 12, and an Fe concentration region 13 on the surface layer side. The respective concentration regions 11 to 13 are formed by heat treatment.

[0119] The soft magnetic alloy 1 having the predetermined concentration regions (11 to 13) can be obtained by the above process. The soft magnetic alloy 1 according to the present embodiment can be applied to various magnetic members such as a coil member of an inductor, a wave filter, an antenna, and particularly preferably to a magnetic core in a coil member such as an inductor. In addition, the soft magnetic alloy 1 can be configured by combining groups of particles having different alloy compositions and particle diameters, and the like, and other magnetic materials not having the respective concentration regions 11 and 12 can be mixedly used. For example, in a magnetic core including the soft magnetic alloy 1, a magnetic material not having the respective concentration regions 11 and 12 can be included, and a resin component can be included.

[0120] (Summary of Embodiments)

[0121] In the soft magnetic alloy 1 of the present embodiment, the Co concentration region 11, the SB concentration region 12, and the Fe concentration region 13 having prescribed characteristics are formed outside the inner region 2 having a soft magnetic alloy composition containing Fe and Co. Also, the SB concentration region 12 and the Fe concentration region 13 satisfy prescribed relationships: (S SB cry / S SB ) < (S Fe cry / S Fe ). By having such characteristics, rust of the soft magnetic alloy 1 at the time of immersion in water can be suppressed, and corrosion resistance can be improved. In particular, by setting the Co concentration degree in the Co concentration region 11 to be more than 1.20, the corrosion resistance of the soft magnetic alloy 1 can be further improved.

[0122] In addition, by forming each of the concentration regions (11 to 13) in the amorphous soft magnetic alloy 1 having an amorphous 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.

[0123] The above describes an embodiment of the present application, but the present application is not limited to the above-described embodiment, and various changes can be made within the scope of the present application.

[0124] Example

[0125] Hereinafter, the present application will be described in more detail based on specific examples. However, the present application is not limited to the following examples. In addition, in the table shown below, the sample number marked with a symbol is a comparative example.

[0126] Experiment 1

[0127] In Experiment 1, a soft magnetic alloy powder was produced by a gas atomization method. In the gas atomization, the following conditions were set: injection temperature of molten metal: 1500°C, injection amount of molten metal: 1.2 kg / min, pressure of high-pressure gas: 7.0 MPa, water pressure of cooling water: 10 MPa, and a soft magnetic alloy powder having an average particle diameter (D50) in the range of 15 to 30 μm on a volume basis was obtained. Then, the soft magnetic alloy powder was subjected to heat treatment under the conditions shown in Table 1, and a soft magnetic alloy of samples 2 to 16 was obtained. In addition, in Experiment 1, a soft magnetic alloy of sample 1 which was not subjected to heat treatment was also produced, and based on this sample 1, the evaluations shown below were performed.

[0128] Composition and Crystal Structure of Soft Magnetic Alloy Powder

[0129] The composition of the soft magnetic alloy powder obtained by the gas atomization method was measured by ICP. As a result, in all of the samples of Experiment 1, it was confirmed that the soft magnetic alloy powder (i.e., the inner 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 (atom ratio; α = 0.300, β = 0, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010). In addition, the soft magnetic alloy powder of Experiment 1 was subjected to X-ray crystal structure analysis by XRD, and as a result, it was confirmed that in all of the samples of Experiment 1, the soft magnetic alloy powder (i.e., the inner region 2) was an amorphous substance having an amorphous degree X of 85% or more.

[0130] <Analysis of the Surface Layer Structure>

[0131] For the soft magnetic alloy of each sample of Experiment 1, a thin sample of the vicinity of the surface layer was taken by the microsampling method using FIB. Then, using this thin sample, mapping analysis was performed by TEM-EDX, and the presence or absence of each concentration region (11 to 13) was investigated. In addition, composition analysis in a specific region was performed by TEM-EELS, and the Co concentration degree in the Co concentration region 11 was measured. In addition, the crystallization area ratio of the SB concentration region 12 and the Fe concentration region 13 was measured by image analysis of the HRTEM image, and the difference DCA in the crystallization area ratio was calculated: (S Fe cry / S Fe )-(S SB cry / S SB ). The analysis results of each sample of Experiment 1 are shown in Table 1.

[0132] Further, in Experiment 1, in the samples in which the Co concentration region 11 was present, it was confirmed that the Co concentration region 11 was an amorphous metallic phase. In addition, in the samples satisfying the relational expression 0 < DCA, it was confirmed that both the SB concentration region 12 and the Fe concentration region 13 were oxide phases, no crystal-induced spots were confirmed in the FFT pattern of the SB concentration region 12, and crystal-induced spots were confirmed in the FFT pattern of the Fe concentration region 13.

[0133] <Saturation Magnetic Flux Density Bs>

[0134] Bs of the soft magnetic alloy of each sample was measured using a vibrating sample magnetometer (VSM) under a magnetic field of 1000 kA / m. The measurement results are shown in Table 1. For this Bs, 1.50 T or more was judged to be good, and 1.70 T or more was judged to be better.

[0135] <Immersion Test>

[0136] First, before the immersion test was performed, a magnetic core sample was produced using the soft magnetic alloy of each sample. The magnetic core sample was produced by the following sequence. 3 parts by mass of an epoxy resin was mixed to 100 parts by mass of the soft magnetic alloy to obtain a granule. Then, the granule was filled into a mold, and press-molding was performed at a pressure of 4 ton / cm 2 to obtain a magnetic core sample in a ring shape having an outer diameter of 11 mmφ, an inner diameter of 6.5 mmφ, and a height of 1.0 mm.

[0137] In order to evaluate the corrosion resistance of the magnetic core sample obtained in the above, an immersion test was performed. In the immersion test, the magnetic core sample was immersed in tap water, and the time until rust was observed by visual observation (rust generation time) was measured. In Experiment 1, the rust generation time of Sample 1 in which heat treatment was not performed was taken as a reference, and the corrosion resistance of each sample was evaluated. Specifically, in Experiment 1, a sample in which the rust generation time was less than 1.3 times the rust generation time of Sample 1 (T1) was set to "F (not good)", a sample in which the rust generation time was 1.3 times or more and less than 1.5 times the rust generation time of Sample 1 (T1) was set to "G (good)", and a sample in which the rust generation time was 1.5 times or more the rust generation time of Sample 1 (T1) was judged to be "VG (particularly good)". The results of the evaluation of the three levels of "F, G, VG" described above are shown in Table 1.

[0138] [Table 1]

[0139]

[0140] As shown in Table 1, in Samples 4 to 8, 10 to 11, and 14 to 16 in which heat treatment was performed under the prescribed conditions, it was confirmed that each of the concentration regions (11 to 13) was formed, and it was confirmed that the relationship 0 < DCA was satisfied. Then, in these samples, it was confirmed that a high Bs could be maintained, and the relative corrosion resistance with respect to the reference alloy (Sample 1) was good. In addition, in Samples 4 to 8, 10 to 11, and 14 to 16, it was confirmed that the vertical distance d1 from the surface 10 to the Co concentration region 11 was 30 nm or less. From these results, it was confirmed that by forming the Co concentration region 11, the SB concentration region 12, and the Fe concentration region 13 having the prescribed characteristics on the surface side of the soft magnetic alloy, the corrosion resistance was improved.

[0141] Experiment 2

[0142] In Experiment 2, the alloy composition was changed to obtain soft magnetic alloys of Samples 17 to 106. The alloy composition of each sample analyzed by ICP is shown in Tables 2 to 7 (part of the evaluation results of Experiment 1 are included).

[0143] Specifically, in Samples 17 to 30 shown in Table 2, the atomic ratio a of Co was changed from the base of the composition formula: (Fe 1-α Co α ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 (atomic ratio; a = 0.300, β = 0, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010) to produce soft magnetic alloys. In addition, Sample 23 is the same sample as Sample 1 of Table 1, and Sample 24 is the same sample as Sample 10 of Table 1.

[0144] In addition, in Samples 31 to 50 shown in Table 3, the atomic ratios of non-metals (B, P, Si, C) and Cr were changed from the base of fixing the atomic ratios of Co, Ni, X1 to a = 0.300, β = 0, γ = 0 to produce soft magnetic alloys.

[0145] In addition, in Samples 51 to 54 shown in Table 4, the atomic ratio β of Ni was changed from the base of the composition formula: (Fe (1-(0.3+β) Co 0.3 Ni β ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 (atomic ratio; a = 0.300, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010) to produce soft magnetic alloys.

[0146] In addition, in Samples 55 to 106 shown in Tables 5 to 7, the atomic ratio of X1 was changed from the base of 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 0.01Based 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, thus creating a soft magnetic alloy.

[0147] 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 marked "Y", and the cases without heat treatment are marked "N". The heat treatment conditions in Experiment 2 were set as follows: holding temperature: 300°C, holding time: 1 h, oxygen concentration in the furnace: 300 ppm, and gauge pressure in the furnace: 0.15 kPa.

[0148] In addition, in Experiment 2, samples 17–106 were subjected to Bs determination and immersion tests, similar to those in Experiment 1. In the immersion test of Experiment 2, the rust formation time T of samples that were not heat-treated with the same composition was measured. 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 < 1.3 are judged as "F (unacceptable)", and samples with a value 1.3 ≤ T are judged as "F (unacceptable)". Y / T N Samples with a value <1.5 are judged as "G (good)" and samples with a value 1.5 ≤ 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.

[0149] [Table 2]

[0150]

[0151] [Table 3]

[0152]

[0153] [Table 4]

[0154]

[0155] [Table 5]

[0156]

[0157] [Table 6]

[0158]

[0159] [Table 7]

[0160]

[0161] As shown in Tables 2 to 7, in the test pieces on which the prescribed heat treatment was performed, higher corrosion resistance than that of the test pieces on which the heat treatment was not performed was obtained. From this result, it was known that, by forming each of the concentration regions 11 to 13 having the prescribed characteristics in the range of the alloy composition shown in Experiment 2, it is possible to maintain a high Bs and improve the corrosion resistance.

[0162] In addition, from the results of Tables 1 to 7, it was known that the Co concentration degree in the Co concentration region 11 is preferably more than 1.20. In addition, it was confirmed that the higher the Co concentration degree, the more the tendency of the improvement effect of the corrosion resistance with respect to the reference alloy (the test piece on which the heat treatment for forming the concentration region was not performed) becomes higher. Furthermore, when the results of Table 2 are supplemented, the more the Co content in the inner region 2 (i.e., the Co content of the soft magnetic alloy), the more the tendency of the rust generation time becomes longer. That is, the more the Co content in the inner region 2, the higher the corrosion resistance as an absolute evaluation. However, as shown in the test piece 30 of Table 2, when the Co content in the inner region 2 is high, the Co concentration degree has a tendency to easily become low. Moreover, in terms of the improvement effect of the corrosion resistance in relative terms (i.e., the corrosion resistance with respect to the reference alloy), the other test pieces 18, 20, 22, 24, 26, 28 having a high Co concentration degree became a more favorable result than the test piece 30.

[0163] Experiment 3

[0164] In Experiment 3, a soft magnetic alloy powder of amorphous phase having an amorphous degree X of 85% or more (test pieces 1, 10), a soft magnetic alloy powder of nanocrystalline having an amorphous degree X of less than 85% (test pieces 107, 108), and a soft magnetic alloy powder of crystalline having an amorphous degree X of less than 85% (test pieces 109, 110) were manufactured, and the influence of the difference in the crystal structure of the soft magnetic alloy on the corrosion resistance was investigated.

[0165] In Experiment 3, the crystal structure of each sample was controlled by the pre-process heat treatment. Specifically, in Samples 1 and 10 of Experiment 3, the pre-process heat treatment was not performed, and therefore, amorphous soft magnetic alloy powders were obtained. In addition, in Samples 107 and 108 of Experiment 3, the pre-process heat treatment was performed at a holding temperature of 500°C, and therefore, nanocrystalline soft magnetic alloy powders were obtained. In addition, in Samples 109 and 110 of Experiment 3, the pre-process heat treatment was performed at a holding temperature of 650°C, and therefore, crystalline soft magnetic alloy powders were obtained. Further, the other conditions in the above-described pre-process heat treatment were set to a temperature increasing rate of 100°C / min, an atmosphere in the furnace of Ar atmosphere, and a gage pressure in the heating furnace of 0.0 kPa, and the crystal structure was controlled in a state where the concentration portion of Co was not formed.

[0166] 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 was 0.5%. In addition, in Experiment 3, for each crystal structure, a sample in which the heat treatment for forming each concentration region (11 to 13) was performed and a sample in which the heat treatment for forming each concentration region (11 to 13) was not performed were prepared, and in Table 8, the case where the heat treatment was performed is described as "Y", and the case where the heat treatment was not performed is described as "N". Further, in the samples (108, 110) in which the pre-process heat treatment was performed, the heat treatment for forming each concentration region was performed after the pre-process heat treatment. In addition, the conditions of the heat treatment in Experiment 3 were set to a holding temperature of 300°C, a holding time of 1.0 h, an oxygen concentration in the heating furnace of 300 ppm, and a gage pressure in the heating furnace of 0.15 kPa.

[0167] In addition, in Experiment 3, the measurement of Bs and the immersion test were also performed similarly to Experiment 2. In the immersion test of Experiment 3, in the same crystal structure, the rust generation time T N of the sample in which the heat treatment was not performed was taken as a reference, and the rust generation time T Y of the sample in which the heat treatment was performed was taken as T Y . The sample in which T N / T Y was less than 1.3 was taken as "F (Fail)", the sample in which 1.3 ≤ T N / T Y was less than 1.5 was taken as "G (Good)", and the sample in which 1.5 ≤ T N / T N was taken as "VG (Very Good)". The evaluation results of Experiment 3 are shown in Table 8.

[0168] [Table 8]

[0169]

[0170] As shown in Table 8, in the samples 108, 110 in which the respective concentration regions 11 to 13 were formed by the prescribed heat treatment, even in the case of the nanocrystalline or crystalline soft magnetic alloy, the corrosion resistance was improved compared with the samples 107, 109 in which the heat treatment was not performed, as in the case of the amorphous soft magnetic alloy. Further, when the results of the samples 107 to 110 shown in Table 8 are compared with the results of the samples 1, 10, it is found that the effect of improving the corrosion resistance is particularly good in the case of the soft magnetic alloy being amorphous.

[0171] Experiment 4

[0172] In Experiment 4, thin strip-shaped soft magnetic alloy samples (samples 111, 112) were produced by the single-roller method. The conditions for the production of the thin strips were set to the temperature of the molten metal sprayed to the roller: 1300°C, the roller temperature: 30°C, the roller rotation speed: 25 m / sec. Further, the chamber was set to an atmospheric atmosphere. The thickness of the soft magnetic alloy thin strips obtained by the above conditions was 20 to 25 μm, the width in the short side direction was about 5 mm, and the length of the thin strips was about 10 m.

[0173] Further, in Experiment 4, the alloy compositions of the samples 111, 112 were measured by ICP, as in Experiment 1, and it was confirmed that the compositions of the samples 111, 112 satisfied the composition formula: (Fe 0.7 Co 0.3 ) 0.84 B 0.11 Si 0.03 C 0.01 Cr 0.01 (atom ratio; α = 0.300, β = 0, γ = 0, a = 0.110, b = 0, c = 0.030, d = 0.010, e = 0.010). Further, the crystal structures of the soft magnetic alloy thin strips of the samples 111, 112 were measured by XRD, and it was confirmed that the samples 111, 112 were amorphous with an amorphous degree X of 85% or more.

[0174] For the soft magnetic alloy ribbon of the sample 111, no heat treatment was performed, but analysis of the surface layer structure, measurement of Bs, and a water immersion test were performed. On the other hand, for the soft magnetic alloy ribbon of the sample 112, heat treatment was performed under the conditions shown in Table 9, and then the same evaluation as the sample 111 was performed. Further, in the water immersion test of the soft magnetic alloy ribbon, a test sample was prepared by cutting the ribbon into an arbitrary size (length of about 4 cm x width of about 5 mm), and the ribbon-shaped test sample was immersed in tap water. The method of the pass / fail determination in Experiment 4 was the same as in Experiment 1. The evaluation results of each sample of Experiment 4 are shown in Table 9. Further, in Table 9, the experimental results of the soft magnetic alloy powder having the same alloy composition as the samples 111, 112 (samples 1, 10 of Experiment 1) are also shown.

[0175] [Table 9]

[0176]

[0177] As shown in Table 9, it was confirmed that even in the case where the soft magnetic alloy has a ribbon shape, by forming each of the concentration regions 11 to 13 through the prescribed heat treatment, it is possible to maintain a high Bs and improve 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 than in the inner region. 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. as well as The Fe-concentrated region exists closer to the surface than the SB-concentrated region and contains Fe. The crystallization area ratio of the SB concentration region is set as S. SB cry / S SB And the crystallization area ratio of the Fe-concentrated region is set as S. Fe cry / S Fe hour, S SB cry / S SB <S Fe cry / S Fe 。 2. The soft magnetic alloy according to claim 1, wherein, The SB enrichment region is an amorphous oxide phase.

3. The soft magnetic alloy according to claim 1 or 2, wherein, The Co-concentrated region is a metallic phase.

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. The Co concentration is the ratio of the Co mass ratio in the Co-concentrated region to the Co mass ratio in the internal region.

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 soft magnetic alloy comprising any one of claims 1 to 7.

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