Magnetic alloy strips, laminates and magnetic cores

Abstract

The present invention relates to a magnetic alloy strip, a laminate, and a magnetic core containing Fe, wherein, when the Fe concentration is measured along the depth direction from the first surface of the strip, a specific depth at which the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the first surface, and the Fe concentration is less than 10 at% from the first surface to the specific depth, and there is a positive increasing region in which the Fe concentration substantially increases with a positive concentration gradient.

Description

Technical Field

[0001] This invention relates to a magnetic alloy strip, a laminate, and a magnetic core. Background Technology

[0002] As the core of ceramic components used in power supply circuits, there are laminated cores. As its raw material, soft magnetic alloy strips with excellent magnetic properties can be cited, but due to the characteristics of metals with low resistance, eddy currents are generated under the alternating magnetic field used, and the resulting core loss becomes significant with increasing frequency.

[0003] To reduce this loss by increasing the resistance between thin strips, techniques for forming an insulating layer on the surface of the thin strips have been used, such as methods formed from non-magnetic oxide particles, as described in Patent Documents 1-3. The thickness of the insulating layer depends on the particle size, and the need for smaller particle sizes to achieve this becomes significantly difficult to achieve in the nanoscale region. Furthermore, it is also difficult to form a smooth insulating layer within the particles.

[0004] Furthermore, the vapor deposition method shown in Patent Document 4 easily forms a smooth layer, but its processing capacity is small and it incurs process costs for use in laminated cores. The formation of a smooth layer can also be achieved through anodizing, as in Patent Documents 5 or 6, but this requires preparing a thin film with a uniform surface state relative to the applied voltage. In addition, due to the wet process, the time required for subsequent drying and other processes increases, making it more complex.

[0005] Furthermore, in these existing technologies, different materials are fixed from the outside to form an insulating layer, but uneven stress is generated at the interface with the alloy surface. The impact becomes greater when the alloy strip is thin, which becomes a cause of the deterioration of magnetic properties.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-51898

[0007] Patent Document 2: Japanese Patent Application Publication No. 2008-150635

[0008] Patent Document 3: Japanese Patent Application Publication No. 62-104009

[0009] Patent Document 4: Japanese Patent No. 2716064

[0010] Patent Document 5: Japanese Patent Application Publication No. 2-133517

[0011] Patent Document 6: Japanese Patent Application Publication No. 61-227194 Summary of the Invention

[0012] The present invention was made in view of the actual situation, and its object is to provide a magnetic alloy strip, laminate and magnetic core with low eddy current loss and excellent magnetic properties when used in a stacked manner.

[0013] The inventors focused on the composition of magnetic alloys along the depth direction from the surface and discovered that by achieving a Fe concentration of 10 at% at a specific depth of 18 nm or more and 500 nm or less from the first surface, even when the alloys are stacked, it is possible to obtain magnetic alloy strips with low eddy current loss and excellent magnetic properties, thus completing the present invention.

[0014] That is, the magnetic alloy strip of the present invention is a magnetic alloy strip containing Fe. When the concentration of Fe is measured along the depth direction from the first surface of the strip, the specific depth at which the concentration of Fe reaches 10 at% is 18 nm or more and 500 nm or less from the first surface. From the first surface to the specific depth, the concentration of Fe is less than 10 at%, and there is a positive increasing region in which the concentration of Fe increases substantially with a positive concentration gradient.

[0015] According to the present invention, a magnetic alloy strip with low eddy current loss and excellent magnetic properties can be provided when used in a stacked configuration. The rationale for this is not necessarily clear, but it is believed that the Fe concentration from the first surface to the aforementioned specific depth is less than 10 at%, and the specific depth where the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the first surface, thereby increasing the insulation resistance near the first surface. Preferably, the specific depth where the Fe concentration reaches 10 at% is 50 nm or more and 400 nm or less from the first surface. Furthermore, if the specific depth where the Fe concentration reaches 10 at% is too deep, there is a tendency for the saturation magnetization rate to deteriorate.

[0016] Preferably, a low-concentration Fe region with a Fe concentration of 0.5 at% or less is continuous at a depth of 10 nm or more, closer to the first surface than the aforementioned positively increasing region. It can be considered that this configuration allows for a further increase in the insulation resistance near the first surface.

[0017] Preferably, the magnetic alloy strip further contains boron (B). Furthermore, it is preferable that the depth of the BO concentration exceeding 0 at% from the first surface is 25 nm or more and less than 360 nm. B₂O₃ generally has high water absorption; therefore, if it appears on the alloy surface, the moisture resistance tends to deteriorate. By ensuring that the depth of the BO concentration exceeding 0 at% from the first surface is 25 nm or more, the deterioration of core loss caused by moisture absorption can be suppressed. However, if the depth of the BO concentration exceeding 0 at% from the first surface is too deep, there is a tendency for the magnetic properties of the magnetic alloy strip to deteriorate.

[0018] Preferably, the magnetic alloy strip has a composition containing 70 at% or more Fe. This configuration improves the magnetic properties of the magnetic alloy strip.

[0019] The thickness of magnetic alloy strips can be less than 100 μm, and even such thin magnetic alloy strips show little deterioration in magnetic properties.

[0020] In this invention, the second surface, which is opposite to the first surface of the thin strip, does not necessarily need to have the same structure as the first surface, but it can also have the same structure. That is, it is also possible that, when measuring the Fe concentration along the depth direction from the second surface, the specific depth at which the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the second surface, and from the second surface to the specific depth, the Fe concentration is less than 10 at%, and there is a positively increasing region where the Fe concentration substantially increases with a positive concentration gradient.

[0021] The laminate of the present invention has a structure in which the magnetic alloy strips described above are laminated. The laminated structure can be either a structure in which one or more alloy strips are wound in the rotational direction, or a structure in which multiple alloy strips are laminated in a single direction.

[0022] The magnetic core of the present invention has the magnetic alloy strip described above. Attached Figure Description

[0023] Figure 1A This is a schematic diagram of a laminate of soft magnetic alloy strips according to one embodiment of the present invention.

[0024] Figure 1B This is a schematic diagram of a laminate according to another embodiment of the present invention.

[0025] Figure 2 This is a graph showing the results of compositional analysis of the Fe content of the soft magnetic alloy strips involved in the embodiments and comparative examples of the present invention, performed along the depth direction from the first surface.

[0026] Figure 3 This is a graph showing the analytical results of the BO content from the surface along the depth direction of the soft magnetic alloy strips involved in the embodiments and comparative examples of the present invention.

[0027] Figure 4 This is an example of a SEM (scanning electron microscope) image on the first surface of a soft magnetic alloy strip according to an embodiment of the present invention.

[0028] Figure 5 It means to Figure 4 The SEM image shown is a magnified portion of an embodiment of the present invention.

[0029] Figure 6 This is related to another embodiment of the present invention. Figure 5 SEM images magnified at the same magnification.

[0030] Symbol Explanation

[0031] 2……(Soft magnetic alloy) thin strip

[0032] 2a……First Surface

[0033] 2b...Second Surface

[0034] 4... Adhesive layer

[0035] 20, 20a...Laminated bodies Detailed Implementation

[0036] The present invention will now be described based on the embodiments shown in the accompanying drawings.

[0037] like Figure 1A As shown, the laminate 20 according to one embodiment of the present invention is used, for example, as a magnetic core. In this laminate 20, a plurality of soft magnetic alloy strips 2 are laminated with an adhesive layer 4 in between. Each magnetic strip 2 has a first surface 2a and a second surface 2b. In this embodiment, adjacent magnetic strips 2 are laminated with their first surfaces 2a and second surfaces 2b facing each other with the adhesive layer 4 in between. Such a lamination method is also referred to as a conventional lamination.

[0038] In this embodiment, the thickness t2 of each magnetic strip 2 is not particularly limited, for example, it is 5 to 150 μm, preferably 100 μm or less, and more preferably 10 to 50 μm, all of which are of the same thickness, but may also be different. Furthermore, the thickness t4 of the adhesive layer 4 is not particularly limited, but is preferably 2 μm or less, or 1 μm or less, or 0.5 μm or less, more preferably 0.1 μm or less, and particularly preferably 0.05 μm or less.

[0039] In this embodiment, the resin constituting the adhesive layer 4 is not particularly limited, and insulating resins such as epoxy resin, phenolic resin, silicone resin, and acrylic resin can be used as examples.

[0040] Next, the magnetic strip 2 will be described in detail.

[0041] (Composition of soft magnetic alloy strips)

[0042] The soft magnetic alloy strip 2 of this embodiment has a composition of (Fe) (1-(α+β)) X1 α X2 β ) (1-(a+b+c+d+e+f)) M a Bb P c Si d C e S f The main components of the composition

[0043] X1 is selected from one or more of Co and Ni.

[0044] X2 is selected from one or more elements including Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements.

[0045] M is selected from one or more of Nb, Hf, Zr, Ta, Mo, W, Ti, and V.

[0046] 0≤a≤0.140、

[0047] 0≤b≤0.200, preferably 0.020≤b≤0.200.

[0048] 0≤c≤0.150、

[0049] 0≤d≤0.090、

[0050] 0≤e≤0.030、

[0051] 0≤f≤0.030、

[0052] α≥0、

[0053] β≥0、

[0054] 0≤α+β≤0.50,

[0055] Preferably, at least one of a, c, and d is greater than 0.

[0056] Furthermore, the soft magnetic alloy strip preferably has a structure containing nanocrystals with Fe as the main component.

[0057] When the soft magnetic alloy strip with the above composition is heat-treated, Fe-based nanocrystals are easily precipitated in the soft magnetic alloy strip 2. In other words, the soft magnetic alloy strip with the above composition can easily serve as a starting material for the soft magnetic alloy strip 2 with Fe-based nanocrystals precipitated.

[0058] Furthermore, the soft magnetic alloy strip with the above composition before heat treatment may also have a structure composed solely of amorphous material, or it may have a nano-heterogeneous structure containing initial microcrystals within the amorphous material. Additionally, the average particle size of the initial microcrystals may be 0.3–10 nm. In this embodiment, when the amorphization rate is 85% or higher, it has a structure composed solely of amorphous material, or it has a nano-heterogeneous structure.

[0059] Here, Fe-based nanocrystals refer to crystals with a nanometer-scale particle size and a bcc (body-centered cubic) lattice structure containing Fe as the main component. In this embodiment, Fe-based nanocrystals with an average particle size of 5–30 nm can also be precipitated. The soft magnetic alloy thin strip 2 precipitated with such Fe-based nanocrystals tends to have a higher saturation magnetic flux density and a lower coercivity. In this embodiment, when the structure contains Fe-based nanocrystals, the amorphization rate is less than 85%.

[0060] The following describes a method for confirming that a soft magnetic alloy ribbon has a structure composed of an amorphous phase (a structure composed only of amorphous phase or a nanostructure) or a structure composed of a crystalline phase. In this embodiment, a soft magnetic alloy ribbon with an amorphization rate X of 85% or more as shown in the following formula (1) has a structure composed of an amorphous phase, and a soft magnetic alloy ribbon with an amorphization rate X of less than 85% has a structure composed of a crystalline phase.

[0061] X=100-[Ic / (Ic+Ia)×100]…(1)

[0062] Ic: Integral intensity of crystalline scattering

[0063] Ia: Integral intensity of amorphous scattering

[0064] Regarding the amorphization rate X, X-ray crystal structure analysis of soft magnetic alloy thin strips is performed by XRD to identify the phase, and the peaks of crystallized Fe or compounds (Ic: integrated intensity of crystalline scattering, Ia: integrated intensity of amorphous scattering) are read. The crystallization rate is calculated based on its peak intensity and is obtained by the above formula (1).

[0065] The following is a detailed description of the components of the soft magnetic alloy strip 2 of this embodiment.

[0066] M is selected from one or more of Nb, Hf, Zr, Ta, Mo, W, Ti, and V.

[0067] The content (a) of M satisfies 0 ≤ a ≤ 0.140. That is, it can also be free of M. The content (a) of M preferably satisfies 0.020 ≤ a ≤ 0.120, more preferably satisfies 0.040 ≤ a ≤ 0.100, and particularly preferably satisfies 0.060 ≤ a ≤ 0.080. When a is large, the saturation magnetic flux density tends to decrease.

[0068] The content of B (b) preferably satisfies 0.020 ≤ b ≤ 0.200. Alternatively, it can be 0.025 ≤ b ≤ 0.200, more preferably 0.060 ≤ b ≤ 0.150, and even more preferably 0.080 ≤ b ≤ 0.120. When b is small, a crystalline phase consisting of crystals with a particle size greater than 30 nm is easily formed in the soft magnetic alloy strip before heat treatment. With the formation of this crystalline phase, it is impossible to precipitate Fe-based nanocrystals through heat treatment. Furthermore, the coercivity tends to increase. When b is large, the saturation magnetic flux density tends to decrease.

[0069] The content of P (c) satisfies 0 ≤ c ≤ 0.150. That is, it is also possible to have no P. In addition, it is preferable to have 0.015 ≤ c ≤ 0.100, or more preferably 0.030 ≤ c ≤ 0.100, and even more preferably 0.030 ≤ c ≤ 0.050. When c is large, the saturation magnetic flux density tends to decrease.

[0070] The Si content (d) satisfies 0 ≤ d ≤ 0.090. That is, it is also possible to have no Si. Furthermore, it is preferable to have 0 ≤ d ≤ 0.020. By including Si, the coercivity tends to decrease. Conversely, when d is large, the coercivity tends to increase.

[0071] The C content (e) satisfies 0 ≤ e ≤ 0.030. That is, it is also possible to have no C. Furthermore, it is preferable to have 0.001 ≤ e ≤ 0.010. By including C, the coercivity is easily reduced. When e is large, a crystalline phase consisting of crystals with a particle size greater than 30 nm is easily formed in the soft magnetic alloy ribbon before heat treatment. When a crystalline phase is formed, it is impossible to precipitate Fe-based nanocrystals through heat treatment. Moreover, the coercivity tends to increase.

[0072] The sulfur content (f) satisfies 0 ≤ f ≤ 0.030. That is, it can also be free of sulfur. When f is large, a crystalline phase consisting of crystals with a particle size greater than 30 nm is easily formed in the soft magnetic alloy ribbon before heat treatment. When a crystalline phase is formed, it is impossible to precipitate Fe-based nanocrystals through heat treatment. Moreover, the coercivity tends to increase.

[0073] Furthermore, in the soft magnetic alloy strip of this embodiment, at least one of a, c, and d is greater than 0. That is, it includes at least one of M, P, and Si. Additionally, at least one of a, c, and d being greater than 0 means that at least one of a, c, and d is 0.001 or more. Alternatively, at least one of a and c may be greater than 0. That is, it may also include at least one of M and P. Furthermore, if a significant reduction in coercivity is desired, a is preferably greater than 0.

[0074] There is no particular limitation on the Fe content (1-(a+b+c+d+e+f)), but it is preferably 0.70 or more (containing more than 70 at% Fe), or 0.73≤(1-(a+b+c+d+e+f))≤0.95, or 0.73≤(1-(a+b+c+d+e+f))≤0.91. By keeping (1-(a+b+c+d+e+f)) within the above range, it is more difficult to generate a crystalline phase composed of crystals with a grain size greater than 30 nm during the manufacture of soft magnetic alloy strips.

[0075] Furthermore, in the soft magnetic alloy strip of this embodiment, a portion of Fe may be replaced by X1 and / or X2.

[0076] X1 is selected from one or more of Co and Ni. Regarding the content of X1, α can be 0. That is, it can also be free of X1. Furthermore, the number of X1 atoms is preferably 40 at% or less, calculated based on 100 at% of the total number of atoms. That is, it is preferable to satisfy 0 ≤ α{1-(a+b+c+d+e+f)} ≤ 0.40.

[0077] X2 is selected from one or more elements chosen from Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements. The content of X2 can also be β = 0. That is, it can also be free of X2. Furthermore, the number of X2 atoms is preferably 3.0 at% or less, calculated based on 100 at% of the total number of atoms. That is, it is preferable to satisfy 0 ≤ β{1-(a+b+c+d+e+f)} ≤ 0.030.

[0078] The range of substitution amounts for Fe with X1 and / or X2 is preferably based on less than half the number of Fe atoms. That is, preferably 0 ≤ α + β ≤ 0.50.

[0079] Furthermore, the soft magnetic alloy strip of this embodiment may also contain elements other than those described above as unavoidable impurities. For example, it may contain less than 0.1% by weight of unavoidable impurities per 100% by weight of the soft magnetic alloy strip.

[0080] (Surface morphology of soft magnetic alloy strip)

[0081] Generally, when a soft magnetic alloy strip 2 is manufactured using a roller method such as the single-roll method, the soft magnetic alloy strip 2 has a first surface 2a (the surface that contacts the surface of the roller) and a second surface 2b (the surface that does not contact the surface of the roller). In addition, the first surface 2a and the second surface 2b are surfaces perpendicular to the thickness direction.

[0082] In this embodiment, the change in Fe content along the depth direction from the surface is measured by performing compositional analysis on the first surface 2a using XPS (X-ray photoelectron spectroscopy). For example, Figure 2 As shown in Ex.1 to Ex.3, the specific depths D1 to D3 where the Fe concentration reaches 10 at% are the distances from the first surface ( Figure 2 The position of the horizontal axis 0 in the chart is above 18nm and below 500nm (preferably 50-400nm). For example, in the context of... Figure 2 In Example 1, the specific depth D1 is about 70 nm; in Example 2, the specific depth D2 is about 140 nm; and in Example 3, the specific depth D3 is about 180 nm.

[0083] In addition, such as Figure 2 As shown, in each embodiment, from the first surface (depth 0 position) to specific depths D1 to D3, there are positively increasing regions P1 to P3, where the Fe concentration is less than 10 at% and the Fe concentration increases substantially with a positive concentration gradient. Moreover, at depths closer to the first surface (depth 0 position) than the positively increasing regions P1 to P3, there are low-concentration Fe regions with an Fe concentration of 0.5 at% or less (preferably 0.3 at% or less) that are continuous at a depth of 10 nm or more (preferably 15 nm or more).

[0084] Furthermore, in this embodiment, such as Figure 3 As shown in Ex.1 to Ex.3, from the first surface ( Figure 3 In the graph (where the horizontal axis 0 is located), the concentration of BO was measured using XPS along the depth direction. From the first surface to at least 20 nm, the concentration of BO was substantially 0 at%. Furthermore, in this embodiment, as... Figure 3 As shown in Ex.1 to Ex.3, there is a BO-containing region with a concentration of more than 1 at% (preferably more than 2 at% or more than 3 at%) in a region deeper than 20 nm (preferably deeper than 30 nm).

[0085] The magnetic properties are improved by including boron (B) in the soft magnetic alloy strip 2.

[0086] Preferably, the depth of BO concentration exceeding 0 at% from the first surface is 25 nm or more but less than 360 nm. B₂O₃ generally has high water absorption; therefore, its presence on the alloy surface tends to deteriorate moisture resistance. By ensuring that the depth of BO concentration exceeding 0 at% from the first surface is 25 nm or more, the degradation of core loss caused by moisture absorption can be suppressed. It should be noted that if the depth of BO concentration exceeding 0 at% from the first surface is too deep, there is a tendency for the magnetic properties of the soft magnetic alloy strip to deteriorate.

[0087] Furthermore, in this embodiment, as Figure 4 As shown, on the first surface 2a, the protrusions with an average height of preferably 7 to 130 nm, and more preferably 10 nm or more and less than 100 nm (hereinafter also referred to as protrusions with a specified height range) are presented in a connected pattern (including mesh).

[0088] It should be noted that, in this embodiment, unlike the first surface 2a, the second surface 2b does not need to have the aforementioned Fe concentration distribution, or BO concentration distribution, or protrusions of a specified height. However, in another embodiment of the present invention, the aforementioned Fe concentration distribution, or BO concentration distribution, or protrusions of a specified height may appear only on the second surface 2b, or on both the first surface 2a and the second surface 2b.

[0089] In the following description, the case in which a protrusion of a specified height appears on the alloy surface of the first surface 2a will be explained.

[0090] When the first surface 2a of the soft magnetic alloy strip 2 of this embodiment is observed, for example, by magnification of 10,000 times using SEM (scanning electron microscope), as... Figure 4 As shown, the convex parts (white areas) are observed to form a connected pattern (including a mesh-like structure). Figure 5 The image shown is an example of an SEM image with the convex portion (white portion) at a specified height further magnified.

[0091] like Figure 5 As shown, the protrusions within a specified height range are formed into an interconnected pattern. Figure 5 The average height of the convex portion shown can be determined, for example, by taking an AFM (atomic force microscope) image.

[0092] In this embodiment, when a protrusion of a specified height exists on the first surface 2a, the area ratio of the protrusion on the first surface 2a is preferably 15% or more and 100% or less, and more preferably 65% ​​or more and 85% or less.

[0093] When determining the presence or absence of convexities, the judgment is made based on the presence or absence of regions that are extremely large in the height distribution of the AFM image in a local area. For example, by limiting the area of ​​the height distribution observed in the AFM image to a local area, within an area of ​​10μm × 10μm, a predetermined number of local areas are randomly selected at intervals of more than 1μm, which can effectively evaluate the presence, height, and area ratio of very small convexities.

[0094] Specifically, when determining the area ratio of convexities, firstly, the height of a 1μm × 1μm quadrilateral region is measured at 40nm intervals (26 × 26 points) using AFM. The presence or absence of convexities is confirmed by adjusting the height distribution relative to the longitudinal and transverse axes. For example, if a maximum value exists that is larger than a specified value (e.g., 10nm) than the center value of the distribution, it is determined that a convexity exists in the 1μm × 1μm region; if such a maximum value does not exist, it is determined that no convexity exists in the 1μm × 1μm region.

[0095] The convexity height can be calculated as the standard deviation σ×4 of the height distribution (equivalent to the maximum-minimum of 95% of a normal distribution). Furthermore, within a 10μm×10μm area, the convexity heights of 20 randomly selected locations at intervals of 1μm or more at 1μm intervals in the four corner regions can be measured, and the average of these convexity heights is taken as the average convexity height. When calculating the convexity area ratio, in areas where there are no convexities exceeding a specified height (e.g., 10nm) above the center value of the distribution, the area of ​​the convexity height in that measured region is calculated as 0. Furthermore, the area ratio of the convexity is obtained by dividing the number of measured locations where convexities exceeding a specified height (e.g., 10nm) above the center value of the distribution by the total number of measured locations.

[0096] (Manufacturing method of soft magnetic alloy thin strip)

[0097] The manufacturing method of the soft magnetic alloy strip according to this embodiment will be described below.

[0098] The method for manufacturing the soft magnetic alloy strip in this embodiment is arbitrary. For example, there is a method for manufacturing soft magnetic alloy strips using a single-roll method. Furthermore, the strip can also be a continuous strip.

[0099] In the single-roller process, firstly, pure metals of each metallic element contained in the final soft magnetic alloy strip are weighed to achieve the same composition as the final soft magnetic alloy strip. Then, the pure metals of each metallic element are melted and mixed to create a master alloy. Furthermore, the method for melting the pure metals is arbitrary; for example, a method involving melting the metals by high-frequency heating after evacuating the chamber. It should be noted that the master alloy and the final soft magnetic alloy strip typically have the same composition.

[0100] Next, the prepared master alloy is heated to melt it, resulting in molten metal (metal melt). There are no particular restrictions on the temperature of the molten metal; for example, it can be set to 1200–1500°C.

[0101] In this single-roller method, molten metal is injected from a nozzle into a rotating roll inside the chamber, thereby producing a thin strip in the direction of the roll's rotation. Furthermore, in this embodiment, the material of the roll is arbitrary. For example, a roll made of Cu can be used.

[0102] In this embodiment, the temperature of the roller is not particularly limited, for example, it is 5 to 30°C, and the pressure difference (injection pressure) between the chamber and the injection nozzle is not particularly limited, for example, it is preferably set to 20 to 80 kPa.

[0103] In the single-roller method, the thickness of the resulting strip 2 can be adjusted primarily by regulating the rotational speed of the roller. However, the thickness of the resulting strip 2 can also be adjusted, for example, by adjusting the distance between the nozzle and the roller or the temperature of the molten metal. Furthermore, when the injection pressure is low, the strip 2 can sometimes be formed by adjusting the distance between the nozzle and the roller or the temperature of the molten metal.

[0104] There are no particular restrictions on the vapor pressure inside the chamber. For example, the vapor pressure inside the chamber can be set to below 11 hPa using Ar gas with dew point conditioning. Furthermore, there is no specific lower limit for the vapor pressure inside the chamber. The vapor pressure can also be set below 1 hPa by filling with dew point-conditioned Ar gas, thus achieving a near-vacuum state.

[0105] The soft magnetic alloy strip 2 before heat treatment preferably does not contain crystals with a particle size greater than 30 nm. Moreover, the soft magnetic alloy strip 2 before heat treatment can have a structure composed solely of amorphous material, or it can have a nano-heterogeneous structure in which microcrystals initially exist within the amorphous material.

[0106] Furthermore, there are no particular limitations on the method for confirming whether the thin band 2 contains crystals with a particle size greater than 30 nm. For example, the presence or absence of crystals with a particle size greater than 30 nm can be confirmed by conventional X-ray diffraction.

[0107] Furthermore, there are no particular limitations on the methods for observing the presence or absence of the aforementioned initial microcrystals and their average particle size. For example, for samples thinned by ion milling, confirmation can be made using a transmission electron microscope to obtain confined-field diffraction images, nanobeam diffraction images, bright-field images, or high-resolution images. When using confined-field diffraction images or nanobeam diffraction images, in the diffraction pattern, ring-shaped diffraction is formed in the case of amorphous materials, while in the case of non-amorphous materials, diffraction spots caused by crystalline structures are formed. Furthermore, when using bright-field images or high-resolution images, by using a magnification of 1.00 × 10⁻⁶... 5 ~3.00×10 5 Visual observation allows for observation of the presence and average particle size of early-stage microcrystals.

[0108] Next, the soft magnetic alloy strip 2 undergoes heat treatment. In this embodiment, by heat treating the first surface 2a (and / or the second surface 2b, hereinafter omitted) of the soft magnetic alloy strip 2 under a specific atmosphere, a specific Fe concentration distribution can be formed on the first surface 2a. Depending on the heat treatment conditions, protrusions of a specified height can also be formed.

[0109] In this embodiment, after a first stage of heat treatment at a predetermined temperature under an active atmosphere, a second stage of heat treatment at a predetermined temperature is performed under an inert atmosphere, thereby forming a specific Fe concentration distribution along the depth direction from the first surface 2a. Examples of gases contained in the active atmosphere include hydrogen as a reducing active atmosphere gas, oxygen as an oxidizing active atmosphere gas, and the atmosphere itself can also be used as an oxidizing active atmosphere gas. Examples of gases contained in the inert atmosphere include nitrogen and argon, and a low oxygen concentration state containing a small amount of oxygen in these gases can also be utilized.

[0110] For the first stage of heat treatment, the conditions are, for example, an atmosphere with a hydrogen concentration of 1–10 vol%, a heat treatment temperature of 200–500 °C, and a heat treatment time of approximately 0.1–5 hours. Furthermore, the conditions for the second stage of heat treatment are, for example, an atmosphere with an oxygen concentration of 0–10 vol%, a heat treatment temperature of 200–500 °C, and a heat treatment time of approximately 0.1–100 hours. Under these heat treatment conditions, a specific Fe concentration distribution is easily formed on the first surface 2a. Moreover, if the heat treatment is performed above the temperature at which Fe-based nanocrystals precipitate, Fe-based nanocrystals will precipitate.

[0111] Increasing the oxygen concentration in an inert atmosphere further deepens the Fe concentration to reach the specific depth of 10 at%. Furthermore, increasing the heat treatment temperature further deepens the Fe concentration to reach the specific depth of 10 at%. Moreover, extending the heat treatment time further deepens the Fe concentration to reach the specific depth of 10 at%.

[0112] It should be noted that in the above embodiments, by exposing only the first surface 2a to a specific atmosphere for heat treatment, a specific Fe concentration distribution is formed only on the first surface. However, it is also possible to expose the second surface 2b to a specific atmosphere for heat treatment. In this case, a specific Fe concentration distribution can also be formed on the first surface 2a and / or the second surface 2b.

[0113] (Summary of this implementation method)

[0114] In this embodiment, when the Fe concentration in the first surface 2a is measured in the depth direction, the specific depth at which the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the first surface. Furthermore, from the first surface to the specific depth, the Fe concentration is less than 10 at%, and there is a positively increasing region where the Fe concentration substantially increases with a positive concentration gradient.

[0115] According to this embodiment, a magnetic alloy strip with low eddy current loss and excellent magnetic properties can be provided when used in a stacked configuration. The reason for this is not necessarily clear, but it is believed that by ensuring the Fe concentration is less than 10 at% from the first surface to a specific depth, and that the specific depth where the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the first surface, the insulation resistance near the first surface can be increased. Furthermore, it is preferable that the specific depth where the Fe concentration reaches 10 at% is 50 nm or more and 400 nm or less from the first surface. Additionally, if the specific depth where the Fe concentration reaches 10 at% is too deep, the magnetic properties (e.g., the rate of change of saturation magnetization) tend to deteriorate.

[0116] Furthermore, in this embodiment, such as Figure 2 As shown in Ex.1 to Ex.3, at a depth closer to the first surface (position 0 on the horizontal axis) than the positively increasing regions P1 to P3, a low-concentration Fe region with a Fe concentration of less than 0.5 at% (essentially 0 at%) is continuous at a depth of more than 10 nm. It can be considered that by constructing it in this way, the insulation resistance near the first surface can be further increased.

[0117] Furthermore, the magnetic alloy strip 2 in this embodiment is a magnetic alloy strip that further contains B, such as... Figure 3As shown in Ex.1 to Ex.3, when the concentration of BO was measured along the depth direction from the first surface (position 0 on the horizontal axis), the concentration of BO was substantially 0 at% up to at least 20 nm from the first surface. Furthermore, there were BO-containing regions with a concentration of more than 1 at% continuously present in the region deeper than 20 nm.

[0118] For example in Figure 3 In Ex.1, a BO-containing region with a concentration exceeding 2 at% is continuously present in a region deeper than 30 nm. Furthermore, in Figure 3 In Ex.2, a BO-containing region with a concentration exceeding 2 at% exists continuously in a region deeper than 60 nm. Furthermore, in Figure 3 In Ex.3, there are BO-containing regions with a concentration of more than 3 at% that are continuously present in a region deeper than 120 nm.

[0119] The magnetic properties are improved by including boron (B) in the soft magnetic alloy strip 2. Furthermore, in this embodiment, as... Figure 3 As shown in EX.1 to EX.3, the depth of BO concentration exceeding 0 at% at the first surface is greater than 25 nm and less than 360 nm (in Figure 3 (The concentration of BO is 25 nm or more but less than 160 nm). B2O3 generally has high water absorption, so if it appears on the alloy surface, the moisture resistance tends to deteriorate. By ensuring that the concentration of BO exceeds 0 at% at a depth of 25 nm or more from the first surface, the deterioration of core loss caused by moisture absorption can be suppressed. Furthermore, if the concentration of BO exceeds 0 at% at a depth too deep from the first surface, there is a tendency for the magnetic properties of the magnetic alloy strip to deteriorate.

[0120] Furthermore, in this embodiment, the soft magnetic alloy strip 2 has a composition containing 70 at% or more Fe. This configuration improves the magnetic properties of the magnetic alloy strip.

[0121] Moreover, in this embodiment, the thickness t2 of the soft magnetic alloy strip 2 can be less than 100 μm, and even with such a thin soft magnetic alloy strip 2, the deterioration of magnetic properties is minimal.

[0122] Furthermore, in this embodiment, on the first surface 2a and / or the second surface 2b, for example, as shown below... Figures 4-6 The protrusions are present as shown. The average height of the protrusions is preferably 7 to 130 nm, and more preferably 10 nm or more but less than 100 nm. The protrusions can exist in a connected pattern (including a mesh pattern).

[0123] By forming such protrusions on the alloy surface, surface wettability can be improved, thereby increasing resin coverage. Furthermore, surface slipability is improved, and through enhanced filling during core forming, magnetic permeability is increased.

[0124] In this embodiment, when a protrusion is formed on the first surface 2a, the area ratio of the protrusion having an average height of 10 nm or more is preferably 15% or more and 100% or less, and more preferably 65% ​​or more and 85% or less. Within such a range, in particular, there is an excellent balance between the increase in the coverage of the resin constituting the adhesive layer 4 relative to the first surface 2a and the increase in magnetic permeability.

[0125] In this embodiment, the laminated structure of the laminate 20 can be either a structure in which one or more alloy strips 2 are wound in the rotational direction, or it can be as follows: Figure 1A The structure shown is formed by stacking multiple alloy strips 2 in the same stacking direction L.

[0126] Or, it can be like Figure 1B As shown, this is a stacked structure (opposite stacked structure) in which adjacent alloy strips 2 have their second surfaces 2b facing each other and their first surfaces 2a facing each other, alternating along the stacking direction L. Figure 1B In the laminate 20a of the illustrated embodiment with a relative laminated structure, the thickness t4a of the adhesive layer 4a disposed at positions where the first surface 2a exhibits a specific Fe concentration distribution is opposite to each other, and / or the thickness t4b of the adhesive layer 4b disposed at positions where the second surface 2b is opposite to each other, is not particularly limited, and can be [missing information]. Figure 1A The thickness t4a of the adhesive layer 4 shown is the same. Alternatively, if a method such as resin impregnation is used, the thickness t4a of the adhesive layer can be essentially set to 0.

[0127] exist Figure 1B In the embodiment shown, it is believed that at the positions where the first surfaces 2a with a specific Fe concentration distribution are opposite each other, a region with a low Fe concentration is formed at its boundary to a degree of 20 nm (10 nm + 10 nm) or more. Even without additional insulating layers other than thin strips, this helps to prevent eddy currents.

[0128] The laminates 20 and 20a of this embodiment can be used, for example, in electric motors, variable transformers, switching power supplies, resonant power supplies, as well as high-frequency transformers, noise filters, chokes, etc.

[0129] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention. For example, insulating sheets made of organic materials such as plastics and rubber may be used instead of adhesive layers 4, 4a, and 4b. In addition, the magnetic alloy strip of the present invention is not limited to soft magnetic alloy strips, but may also be hard magnetic alloy strips.

[0130] Example

[0131] The present invention will now be described with reference to more detailed embodiments, but the present invention is not limited to these embodiments.

[0132] Example 1

[0133] To become Fe 82 Nb 5.5 B9P 1.5 The Si2 alloy composition involves weighing the raw metal and melting it using high-frequency heating to create a master alloy. This master alloy is then heated to melt, producing a molten metal at 1250°C. The molten metal is then sprayed onto a single-roller rotating at 25 m / sec to create a thin strip. It should be noted that the roller is made of Cu.

[0134] The roller temperature is set to 10–20°C. The pressure difference (injection pressure) between the chamber and the injection nozzle is 30–80 kPa. The resulting soft magnetic alloy strip has a thickness of 20–30 μm and a length of tens of meters.

[0135] For soft magnetic alloy ribbons, Fe-based nanocrystals are precipitated and then heat-treated under a specific atmosphere. In the first stage, hydrogen gas with a concentration of 2% by volume in nitrogen is used, the heat treatment temperature is set to 300°C, and the heat treatment time is set to 1 hour. In the second stage, oxygen gas with a concentration of 0.2% by volume in nitrogen is used, the heat treatment temperature is set to 400°C, and the heat treatment time is set to 1 hour.

[0136] Compositional analysis was performed on the surface (first surface) of the heat-treated ribbon sample using XPS (X-ray photoelectron spectroscopy) along the depth direction. The results of investigating the Fe concentration distribution (at%) along the depth direction from the surface are shown below. Figure 2 Example 1. Figure 2 As shown, the specific depth D1 where the Fe concentration reaches 10 at% (in Table 1, the depth at which Fe reaches 10 at%) can be confirmed is about 70 nm from the position of the horizontal axis 0, which is more than 18 nm and less than 500 nm (or 50-400 nm).

[0137] In addition, such as Figure 2As shown, it can be confirmed that in Example 1, from the position at surface depth 0 to a specific depth D1, the Fe concentration is less than 10 at%, and there is a positively increasing region P1 where the Fe concentration substantially increases with a positive concentration gradient. Moreover, it can be confirmed that at depths closer to the position at depth 0 than the positively increasing region P1, a low-concentration Fe region with a Fe concentration of less than 0.5 at% (substantially 0 at%) is continuous at a depth of 15 nm or more.

[0138] Furthermore, in Example 1, as Figure 3 As shown in Ex.1, from the first surface ( Figure 3 In the graph (where the horizontal axis 0 is located), the concentration of BO was measured using XPS along the depth direction, confirming that the concentration of BO was substantially 0 at% from the first surface up to at least 20 nm. Furthermore, in Example 1, as... Figure 3 As shown in Ex.1, it can be confirmed that there are BO-containing regions with a concentration of more than 2 at% or more than 3 at% in a region deeper than 20 nm (preferably deeper than 30 nm).

[0139] Furthermore, such as Figure 3 As shown, it can be confirmed that in Example 1, the depth of the first surface where the concentration of BO exceeds 0 at% (also recorded in Table 1 as "BO manifestation depth") is approximately 35 nm, which is more than 25 nm and less than 360 nm.

[0140] The saturation magnetization of the thin strip sample of Example 1 was measured using a vibrating sample magnetometer (VSM) at a magnetic field of 1500 kA / m. For Comparative Example 1 described later, the rate of decrease (expressed as a percentage) compared to the saturation magnetization value measured under the same conditions was calculated as the rate of change of saturation magnetization. A rate of change of saturation magnetization closer to 0% is preferred; -5% or more was defined as VG, less than -5% but more than -10% as G, and less than -11% as NG. The results are shown in Table 1.

[0141] Furthermore, a stacked toroidal magnetic core was fabricated using a thin strip sample with a specific Fe concentration distribution formed on its first surface. First, a 38 μm thick PET film was laminated as an insulating layer onto the second surface of the thin strip using acrylic resin with an adhesive. Next, the thin strip with the laminated insulating layer was punched into a ring shape with an outer diameter of 18 mm and an inner diameter of 10 mm. Ten of these punched thin strip sheets were then used to fabricate multiple [types of magnetic cores]. Figure 1A The sample shown is a toroidal magnetic core consisting of multiple alloy strips 2 stacked in the same stacking direction L.

[0142] Ten thin strips obtained from punching are used to manufacture multiple... Figure 1BAs shown, a sample of a toroidal magnetic core is shown, in which adjacent alloy strips 2 second surfaces 2b are stacked opposite each other along the stacking direction L, and adjacent alloy strips 2 first surfaces 2a are stacked opposite each other.

[0143] The core loss of the obtained stacked toroidal core sample was measured using a BH analyzer at 75 mT and 600 kHz to determine the optimal stacking method. Figure 1A Change to Figure 1B The resulting increase in core loss (in percentage terms) was calculated. Core loss was calculated as the average of three samples. An increase in core loss of 10% or more was designated as NG, less than 10% as G, and less than 6% as VG. The results are shown in Table 1.

[0144] Furthermore, for samples with three stacked toroidal magnetic cores, the core loss before and after the humidity test was determined under the same measurement conditions as described above, and the increase rate (%) of core loss before and after the test was calculated. The humidity test was conducted based on JIS C60068-2-38:2013 "Environmental Test Methods (Electrical and Electronic) Temperature and Humidity Combination (Cyclic) Test Method". However, 10 cycles were performed without the low-temperature sub-cycle. A core loss increase rate of 5% or more was defined as NG, less than 5% as G, and less than 3% as VG. The results are shown in Table 1.

[0145] Example 2

[0146] Except for the conditions under which the heat treatment of the strip was performed, the strip sample and the sample of the stacked toroidal magnetic core were formed in the same manner as in Example 1, and the same evaluation was performed as in Example 1. The results are shown in Table 1.

[0147] In Example 2, the oxygen concentration in the second stage heat treatment was set to approximately 15 times that of Example 1.

[0148] The results of the Fe concentration measurement along the depth direction from the first surface in Example 2 are shown below. Figure 2 Ex.2, and the determination results of BO are shown in Figure 3 Ex.2 in the example.

[0149] In Example 2, as Figure 2 As shown, it can be confirmed that the specific depth D2 where the Fe concentration reaches 10 at% (in Table 1, the depth at which Fe reaches 10 at%) is from the position of the horizontal axis 0 to about 140 nm, which is above 18 nm and below 500 nm (or 50 to 400 nm).

[0150] In addition, such as Figure 2As shown, it can be confirmed that in Example 2, from the surface depth 0 to a specific depth D2, the Fe concentration is less than 10 at%, and there is a positively increasing region P2 where the Fe concentration substantially increases with a positive concentration gradient. Moreover, it can be confirmed that at depths closer to the depth 0 than the positively increasing region P2, a low-concentration Fe region with a Fe concentration of less than 0.5 at% (substantially 0 at%) is continuous at a depth of 15 nm or more.

[0151] Furthermore, in Example 2, as Figure 3 As shown in Ex.2, from the first surface ( Figure 3 In the graph (where the horizontal axis 0 is located), the concentration of BO was measured using XPS along the depth direction, confirming that the concentration of BO was substantially 0 at% from the first surface up to at least 20 nm. Furthermore, in Example 2, as... Figure 3 As shown in Ex.2, it can be confirmed that there are BO-containing regions with a concentration of more than 2 at% or more than 3 at% in a region deeper than 20 nm (actually deeper than 60 nm).

[0152] Furthermore, such as Figure 3 As shown, it can be confirmed that in Example 2, the depth of the first surface where the concentration of BO exceeds 0 at% (also recorded in Table 1 as "BO manifestation depth") is approximately 65 nm, which is more than 25 nm and less than 360 nm.

[0153] Furthermore, the SEM image of the first surface in Example 2 is shown below. Figure 4 and Figure 5 The surface (first surface) of the heat-treated ribbon sample was observed using SEM and AFM, and convexities with an average height of more than 10 nm and less than 100 nm were observed.

[0154] Example 3

[0155] Except for the conditions under which the heat treatment of the strip was performed, the strip samples and the stacked annular samples were formed in the same manner as in Example 2, and the same evaluation was performed as in Example 2. The results are shown in Table 1. In Example 3, the heat treatment time in the second stage was set to approximately 7 times the heat treatment time of Example 2.

[0156] Furthermore, the measurement results of the Fe concentration measured from the first surface along the depth direction in Example 3 are shown below. Figure 2 Ex.3 shows the determination results of BO. Figure 3 Ex.3 in the example.

[0157] In Example 3, as Figure 2As shown, it can be confirmed that the specific depth D3 where the Fe concentration reaches 10 at% (in Table 1, the depth at which Fe reaches 10 at%) is from the position of the horizontal axis 0 to about 180 nm, which is above 18 nm and below 500 nm (or 50 to 400 nm).

[0158] In addition, such as Figure 2 As shown, it can be confirmed that in Example 3, from the surface depth 0 to a specific depth D3, the Fe concentration is less than 10 at%, and there is a positively increasing region P3 where the Fe concentration substantially increases with a positive concentration gradient. Moreover, it can be confirmed that at depths closer to the depth 0 than the positively increasing region P3, a low-concentration Fe region with a Fe concentration of less than 0.5 at% (substantially 0 at%) is continuous at a depth of 15 nm or more.

[0159] Furthermore, in Example 3, as Figure 3 As shown in Ex.3, from the first surface ( Figure 3 In the graph (where the horizontal axis is 0), the concentration of BO was measured using XPS along the depth direction, confirming that the concentration of BO was substantially 0 at% from the first surface up to at least 20 nm. Furthermore, in Example 3, as... Figure 3 As shown in Ex.3, in regions deeper than 20 nm (actually deeper than 120 nm), there are continuous BO-containing regions with a concentration of more than 2 at% or more than 3 at%.

[0160] Furthermore, such as Figure 3 As shown, it can be confirmed that in Example 3, the depth of the first surface where the concentration of BO exceeds 0 at% (also recorded in Table 1 as "BO manifestation depth") is approximately 129 nm, which is more than 25 nm and less than 360 nm.

[0161] Furthermore, the SEM image of the first surface in Example 3 is shown in... Figure 6 The surface (first surface) of the heat-treated ribbon sample was observed using SEM and AFM, and convexities with an average height of more than 10 nm and less than 100 nm were observed.

[0162] Comparative Example 1

[0163] Except for not performing heat treatment on the strip, the strip sample and the stacked annular sample were formed in the same manner as in Example 1, and the same evaluation was performed as in Example 1. The results are shown in Table 1. In addition, the Fe concentration and BO concentration measured from the first surface along the depth direction in Comparative Example 1 are shown in Table 1. Figure 2 and Figure 3 Cex.1 in the middle.

[0164] like Figure 2As shown, it can be confirmed that in Comparative Example 1, the Fe concentration is 10 at% or more at a position within 18 nm of the surface depth 0.

[0165] Furthermore, in Comparative Example 1, such as Figure 3 As shown in Cex.1, it can be confirmed that from the first surface ( Figure 3 In the graph (where the horizontal axis 0 is located), the concentration of BO was determined by XPS along the depth direction, and a peak of BO concentration appeared in the range from the first surface to at least 20 nm.

[0166] Furthermore, for Comparative Example 1, even when observing the SEM image of the first surface, no abnormalities were observed. Figures 4-6 The convex portion within the specified height range shown.

[0167] Comparative Example 2

[0168] Except for the conditions under which the heat treatment of the strip was performed, the strip samples and the stacked annular samples were formed in the same manner as in Example 2, and the same evaluation was performed as in Example 2. The results are shown in Table 1.

[0169] In Comparative Example 2, the heat treatment temperature in the second stage was set to be about 100°C lower than the heat treatment temperature in Example 2.

[0170] Example 4

[0171] Except for the conditions under which the heat treatment of the strip was performed, the strip samples and the stacked annular samples were formed in the same manner as in Example 2, and the same evaluation was performed as in Example 2. The results are shown in Table 1.

[0172] In Example 4, the heat treatment time in the second stage is set to approximately 50 times the heat treatment time in Example 2.

[0173] Example 5

[0174] Except for the conditions under which the heat treatment of the strip was performed, the strip samples and the stacked annular samples were formed in the same manner as in Example 4, and the same evaluation was performed as in Example 4. The results are shown in Table 1.

[0175] In Example 5, the heat treatment temperature in the second stage was set to be about 50°C higher than the heat treatment temperature in Example 4.

[0176] Comparative Example 3

[0177] Except for the conditions under which the heat treatment of the strip was performed, the strip samples and the stacked annular samples were formed in the same manner as in Example 5, and the same evaluation was performed as in Example 5. The results are shown in Table 1.

[0178] In Comparative Example 3, the heat treatment time in the second stage was set to approximately three times the heat treatment time of Example 5.

[0179] Example 10

[0180] Except for the conditions under which the heat treatment of the strip was performed, the strip sample and the stacked annular sample were formed in the same manner as in Comparative Example 2, and the same evaluation was performed as in Comparative Example 2. The results are shown in Table 1.

[0181] In Example 10, the heat treatment temperature in the second stage was set to be about 50°C higher than the heat treatment temperature in Comparative Example 2.

[0182] Example 6

[0183] The raw material metal was weighed to form an alloy composition of Fe79B13.5Cu2Si5.5. The first stage of heat treatment of the strip was carried out under an oxidizing atmosphere. Otherwise, strip samples and stacked annular samples were formed in the same manner as in Example 1, and the same evaluation was performed. The results are shown in Table 1.

[0184] Example 7

[0185] Compared to Example 6, the oxygen concentration in the second stage was set to approximately 15 times. Otherwise, the thin strip samples and stacked annular samples were formed in the same manner as in Example 6, and the same evaluation was performed. The results are shown in Table 1.

[0186] Example 8

[0187] Compared to Example 7, except that the heat treatment time was set to approximately 7 times, thin strip samples and stacked annular samples were formed in the same manner as in Example 7, and the same evaluation was performed. The results are shown in Table 1.

[0188] Comparative Example 4

[0189] Except for not performing heat treatment on the strip, the strip samples and stacked annular samples were formed in the same manner as in Example 6, and the same evaluation was performed as in Example 6. The results are shown in Table 1. It should be noted that the saturation magnetization change rates of Examples 6 to 8 in Table 1 are relative to Comparative Example 4.

[0190] Comparative Example 5

[0191] Except for the heat treatment conditions for the thin strip, the thin strip samples and stacked annular samples were formed in the same manner as in Example 6, and the same evaluation was performed as in Example 6. The results are shown in Table 1.

[0192] In Comparative Example 5, the heat treatment temperature in the second stage was set to be about 100°C lower than the heat treatment temperature in Example 6.

[0193] evaluate

[0194] As shown in Table 1, compared with Comparative Examples 1-5, it can be confirmed that in Examples 1-8 and 10, a specific Fe concentration distribution is formed on the alloy surface at a predetermined depth from the surface, thereby reducing the increase rate of core loss and the rate of change of saturation magnetization. Furthermore, it can be confirmed that the specific depth at which the Fe concentration reaches 10 at% is 50 nm or more and 400 nm or less from the first surface, further reducing the increase rate of core loss and the rate of change of saturation magnetization. In addition, the depth position at which the BO concentration increases by more than 0 at% from the first surface (the BO manifestation depth in Table 1) is preferably 25 nm or more, and more preferably 35 nm or more, confirming that the deterioration of core loss caused by moisture absorption can be effectively suppressed.

[0195]

Claims

1. A magnetic alloy thin strip, wherein, The magnetic alloy strip contains Fe. When the Fe concentration is measured along the depth direction from the first surface of the thin strip, the specific depth at which the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the first surface. From the first surface to the specific depth, the Fe concentration is less than 10 at%, and there is a positive increasing region where the Fe concentration increases substantially with a positive concentration gradient. At a depth closer to the first surface than the positively increasing region, a low-concentration Fe region with a Fe concentration of less than 0.5 at% is continuous at a depth of more than 10 nm.

2. The magnetic alloy strip according to claim 1, wherein, The magnetic alloy strip also contains B.

3. The magnetic alloy strip according to claim 2, wherein, The concentration of BO exceeding 0 at% is located at a depth of more than 25 nm and less than 360 nm from the first surface.

4. The magnetic alloy strip according to claim 1, wherein, The magnetic alloy strip has a composition containing more than 70 at% Fe.

5. The magnetic alloy strip according to claim 1, wherein, The thickness of the magnetic alloy strip is less than 100 μm.

6. The magnetic alloy strip according to claim 1, wherein, When the Fe concentration is measured along the depth direction from the second surface located on the opposite side of the first surface of the thin strip, the specific depth at which the Fe concentration reaches 10 at% is 18 nm or more and 500 nm or less from the second surface. From the second surface to the specific depth, the Fe concentration is less than 10 at%, with a positive increasing region where the Fe concentration increases substantially with a positive concentration gradient.

7. The magnetic alloy strip according to claim 1, wherein, The magnetic alloy strip is made of a soft magnetic alloy.

8. A layered body, wherein, The laminate has a structure in which the magnetic alloy strip of claim 1 is laminated.

9. A magnetic core, wherein, The magnetic core has a magnetic alloy strip as described in any one of claims 1 to 7 or a laminate as described in claim 8.

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