Iron-based nanocrystalline soft magnetic alloy powder, soft magnetic composite material and preparation method thereof

Abstract

The present invention provides an iron-based nanocrystalline soft magnetic alloy powder, a soft magnetic composite material and a preparation method thereof, belonging to the technical field of soft magnetic materials. The iron-based nanocrystalline soft magnetic alloy powder has a heterogeneous nanocrystalline structure comprising a three-dimensional island-shaped amorphous region and a nanocrystalline region. The diameter of the three-dimensional island-shaped amorphous region is 50-100 nm, and the number density of the three-dimensional island-shaped amorphous region is 10 19 ‑10 20 m ‑3 The iron-based nanocrystalline soft magnetic alloy powder has the advantages of high sphericity, high saturation magnetization and low coercive force; the soft magnetic composite material comprises soft magnetic powder and a coating layer coated on the surface of the soft magnetic powder, and the coating layer comprises a binder, wherein the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention, or is composited with at least one of iron-nickel, iron-nickel-molybdenum, iron-silicon, iron-silicon-aluminum, iron-silicon-chromium, carbonyl iron and pure iron powder, and has the advantages of low high-frequency loss, high magnetic permeability and high DC bias.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic materials, and in particular to an iron-based nanocrystalline soft magnetic alloy powder, a soft magnetic composite material and a preparation method thereof. Background Art

[0002] With the advancement and innovation of science and technology, electronic devices and magnetic devices are developing towards large capacity, miniaturization, high efficiency and high frequency stability. Magnetic materials are indispensable materials in the field of electronic devices and magnetic devices, and have huge application space and innovative significance. Soft magnetic materials are one of the most widely used and diverse materials. Soft magnetic materials have low coercivity ( H c ), high magnetic permeability ( μ e ), high saturation magnetization ( M s ) and low power loss ( P cv ) and is an important component of electromagnetic conversion devices. It can also be used in signal processing equipment and is widely used in various transformers, controllers, sensors and magnetic recording equipment. Soft magnetic materials include crystalline soft magnetic materials, ferrite soft magnetic materials, metal magnetic powder materials, magnetic films, and amorphous and nanocrystalline soft magnetic materials. Soft magnetic composite materials are a type of metallic soft magnetic material that is made by mixing and pressing ferromagnetic powder and insulating medium and has a distributed air gap. They have unique advantages such as low eddy current loss, high resistivity, good DC bias performance, easy machining, three-dimensional isotropy and a wide operating frequency range. They are widely used in switching power supplies, filter inductors, main transformers, inductors and high-frequency chokes.

[0003] Iron-based nanocrystalline alloys generally refer to complex phase alloys characterized by a microstructure characterized by a uniform distribution of nanoscale α-Fe crystals (including α-Fe crystals containing solid solutions of other elements such as Si, Co, and Ni) within an amorphous matrix. Preparing iron-based nanocrystalline alloys into powders and fabricating them into soft magnetic composites using powder metallurgy processes combines the advantages of both iron-based nanocrystalline alloys and soft magnetic composites, resulting in a new generation of high-performance soft magnetic materials—nanocrystalline soft magnetic composites—that are driving the development of high-frequency, high-performance electronic devices and power equipment, as well as related industries. Since the invention of the FeSiBNbCu nanocrystalline alloy by Yoshizawa et al. in Japan in 1988, academia and industry have conducted extensive research and explored the industrialization of iron-based nanocrystalline alloys. Literature (Journal of Applied Physics 64 (1988) 6044, Journal of Alloys and Compounds 810 (2019) 151754, Journal of Magnetism and Magnetic Materials 501 (2020) 166457) and patents (CN10126324B, CN104934179B) etc. disclose iron-based nanocrystalline alloys in the form of strips or powders. Transmission electron microscopy analysis shows that their microstructures are uniform nanocrystalline structures, that is, a complex phase structure in which nanoscale α-Fe crystal phases are uniformly distributed in an amorphous matrix. Since the resistivity of the crystalline phase is lower than that of the amorphous phase, the resistivity of nanocrystalline alloys with uniform structure is generally lower than that of amorphous alloys. Fe with uniform nanocrystalline structure 73.5 Si 13.5 The resistivity of B9Cu1Nb3 alloy is 1.15 μΩ·m, while Fe 78 Si9B 13 The resistivity of amorphous alloys is 1.35 μΩ·m. This relatively low resistivity is not conducive to reducing eddy current losses in high-frequency applications, making it difficult to adapt to the high-frequency trend of future power electronic devices.

[0004] The shape of iron-based nanocrystalline soft magnetic alloy powder has a crucial influence on its high-frequency magnetic properties. Due to the weak amorphous-forming ability of iron-based nanocrystalline alloys, it is usually only possible to obtain completely amorphous precursor thin strips through the single-roller spinning method with a high cooling rate. After heat treatment, it is crushed by ball milling to obtain nanocrystalline soft magnetic alloy powders. However, these powders have sharp edges and corners, making them difficult to insulate and coat, resulting in very high high-frequency losses of soft magnetic composite materials, which seriously limits their application in higher frequency bands. Spherical or ellipsoidal alkali metal powders prepared by atomization have good coatability and can effectively reduce the losses of soft magnetic composite materials at high frequencies. However, the traditional gas atomization method has poor cooling capacity and it is difficult to obtain completely amorphous precursor powders, resulting in deterioration of the performance of the prepared nanocrystalline alloy powders. Although water atomization and water-gas combined atomization methods have better cooling capacity, the powders prepared by them have problems such as high oxygen content and poor sphericity. Patent CN202311271977.2 discloses an iron-based nanocrystalline soft magnetic alloy powder, but its preparation method is ball milling, which results in relatively high high-frequency loss.

[0005] In summary, in order to promote the development of power equipment and magnetic devices towards high frequency and high power, it is necessary to develop nanocrystalline soft magnetic alloy spherical powders with excellent soft magnetic properties, high resistivity and high sphericity, and to develop soft magnetic composite materials with high frequency and low loss, high magnetic permeability and high DC bias performance. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides an iron-based nanocrystalline soft magnetic alloy powder, a soft magnetic composite material and a preparation method thereof. The iron-based nanocrystalline soft magnetic alloy powder has both excellent soft magnetic properties and high resistivity, and the soft magnetic composite material has high frequency and low loss, high magnetic permeability and high DC bias performance.

[0007] The specific technical solutions of the present invention are:

[0008] In a first aspect, the present invention provides an iron-based nanocrystalline soft magnetic alloy powder, wherein the powder particles have a heterogeneous nanocrystalline structure, wherein the heterogeneous nanocrystalline structure comprises a three-dimensional island-shaped amorphous region and a nanocrystalline region, wherein the diameter of the three-dimensional island-shaped amorphous region is 50-100 nm, and the number density of the three-dimensional island-shaped amorphous region is between 10 19-20 m -3 Order of magnitude.

[0009] The iron-based nanocrystalline soft magnetic alloy powder provided by the present invention has a special inhomogeneous nanocrystalline structure. In addition to the nanocrystalline region composed of the conventional nanoscale α-Fe crystal phase and the amorphous matrix phase, the inhomogeneous nanocrystalline structure also has a three-dimensional island amorphous region. The amorphous matrix phase in the inhomogeneous nanocrystalline structure is isotropic and does not have magnetic anisotropy; the amorphous matrix phase has a large positive magnetostriction coefficient, while the α-Fe crystal phase has a small negative magnetostriction coefficient. When the inhomogeneous nanocrystalline structure contains a three-dimensional island amorphous region, the amorphous matrix phase and the α-Fe crystal phase can be balanced, so that the iron-based nanocrystalline soft magnetic alloy powder has a magnetostriction coefficient close to 0, reducing the remanence of the iron-based nanocrystalline soft magnetic alloy powder and increasing its magnetic permeability, which also helps the iron-based nanocrystalline soft magnetic alloy powder to obtain excellent soft magnetic properties; further combined with regulating the diameter of the three-dimensional island amorphous region in the inhomogeneous nanocrystalline structure to be 50-100 nm and the number density to be 10 19 -10 20 m -3 The invention discloses an iron-based nanocrystalline soft magnetic alloy powder having a magnetostriction coefficient close to 0 to the greatest extent, and overcomes the problem of low resistivity caused by the α-Fe crystal phase, thereby significantly improving the resistivity of the iron-based nanocrystalline soft magnetic alloy powder and helping to reduce the high-frequency loss of the soft magnetic composite material. The iron-based nanocrystalline soft magnetic alloy powder provided by the present invention has both excellent soft magnetic properties and high resistivity through the coordinated cooperation of the three-dimensional island-shaped amorphous region and the nanocrystalline region in the heterogeneous nanocrystalline structure.

[0010] In one possible embodiment, the nanocrystalline region comprises a nanoscale α-Fe crystal phase and an amorphous matrix phase, wherein the average diameter of the α-Fe crystal phase is 8-14 nm, and the number density of the α-Fe crystal phase is between 10 22 -10 23 m -3 The general α-Fe crystal phase has magnetocrystalline anisotropy, and when the average diameter of the α-Fe crystal phase in the heterogeneous nanocrystalline structure is 8-14 nm and the number density is 10 22 -10 23 m -3 When the order of magnitude is reached, the magnetic cross-coupling between the α-Fe crystal phases can significantly reduce the magnetocrystalline anisotropy, which is beneficial to reducing the coercive force and remanence of the iron-based nanocrystalline soft magnetic alloy powder and increasing its magnetic permeability, so that the iron-based nanocrystalline soft magnetic alloy powder has excellent soft magnetic properties.

[0011] In a possible embodiment, the chemical element composition of the iron-based nanocrystalline soft magnetic alloy powder satisfies the relationship: Fe a Co b Ni c Si d B eP f C g Nb h Cu i , where the subscripts a, b, c, d, e, f, g, h, and i represent the atomic percentage of each alloying element, respectively, and satisfy the following conditions: 59 ≤ a ≤ 72; 0 ≤ b ≤ 10; 0 ≤ c ≤ 5; 69 ≤ a+b+c ≤72; 12.5 ≤ d ≤ 15.5; 9 ≤ e ≤ 12; 0 ≤ f ≤ 2; 0 ≤ g ≤ 2; 3 ≤ h ≤ 5; 0.6 ≤i ≤ 0.9; a+b+c+d+e+f+g+h+i=100. The iron-based nanocrystalline soft magnetic alloy component of the above-mentioned composition has high Si, B and Nb contents, so that the alloy has good amorphous forming ability and low Cu content. Combined with the multi-stage atomization powder making process provided by the present invention, the iron-based nanocrystalline soft magnetic alloy powder with a heterogeneous nanocrystalline structure described in the present invention can be obtained.

[0012] In one possible embodiment, the powder particles are spherical or quasi-spherical, with an average sphericity of ≥0.9. Spherical powder particles have a smooth surface, few defects, low resistance to domain wall movement during magnetization, better magnetic isotropy, less inter-grain pinning, and are easily coated, which can reduce hysteresis loss and eddy current loss between powders at high frequencies. Controlling the average sphericity of the powder particles to ≥0.9 can help reduce hysteresis and eddy current losses in iron-based nanocrystalline soft magnetic alloy powders, improve magnetic permeability, and reduce coercivity.

[0013] In one possible embodiment, the iron-based nanocrystalline soft magnetic alloy powder has a saturation magnetization of 100-145 emu / g and a coercivity of less than 2 Oe. The higher saturation magnetization of the iron-based nanocrystalline soft magnetic alloy powder helps increase the power density of the soft magnetic composite material, while the lower coercivity helps reduce hysteresis losses in the soft magnetic composite material.

[0014] In a second aspect, the present invention also provides a method for preparing the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, comprising the following steps:

[0015] S1: A multi-stage pulverization and atomization process is used to prepare an amorphous precursor powder from a master alloy of an iron-based nanocrystalline soft magnetic alloy. The multi-stage pulverization and atomization process includes four steps, namely, melting the master alloy, gas atomization of the alloy melt, mechanical atomization by a rotary disk, and water cooling. The distance between the gas outlet of the alloy melt gas atomization and the rotary disk in the rotary disk mechanical atomization step is 110-130 mm, and the rotary disk rotation speed in the rotary disk mechanical atomization step is 6000-20000 rpm.

[0016] S2: using a rotary annealing furnace to perform vacuum or inert gas protection heat treatment on the amorphous precursor powder in step S1 to obtain iron-based nanocrystalline soft magnetic alloy powder, wherein the heat treatment temperature is 560-620 ° C, the time is 0.5-2 hours, and the sample chamber rotation rate is 5-60 rpm.

[0017] The preparation method of the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention adopts a multi-stage crushing and atomization process and controls key process parameters such as the distance between the gas outlet in the gas atomization stage and the turntable in the turntable mechanical atomization link and the turntable speed in the high-speed turntable mechanical atomization link, so that the iron-based nanocrystalline soft magnetic alloy can obtain a completely amorphous precursor powder and form local depletion of the Cu element therein. In the subsequent heat treatment process, the temperature and time of the heat treatment are controlled to form a three-dimensional island-shaped amorphous region in the local depletion of the Cu element and a nanocrystalline region containing an α-Fe crystal phase in the Cu element-enriched region, thereby obtaining an iron-based nanocrystalline soft magnetic alloy powder with the described heterogeneous nanocrystalline structure.

[0018] In a third aspect, the present invention further provides a soft magnetic composite material comprising a soft magnetic powder and a coating coated on the surface of the soft magnetic powder, wherein the coating comprises a binder. The soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention, or the soft magnetic powder is a composite of the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention and a crystalline metal powder, wherein the crystalline metal powder comprises at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder, and pure iron powder. The soft magnetic composite material exhibits excellent magnetic properties, including low loss at high frequencies, high magnetic permeability, and high DC bias performance.

[0019] In one possible embodiment, the binder includes at least one of epoxy resin, silicone resin, and phenolic resin. Epoxy resin has strong bonding strength with soft magnetic powder, reducing interfacial defects and improving the mechanical properties of the soft magnetic composite. Silicone resin has excellent high-temperature resistance, which helps improve the high-temperature stability of the soft magnetic composite. Phenolic resin has a cost advantage, which helps reduce the production cost of the soft magnetic composite.

[0020] In one possible embodiment, the mass of the binder is 1%-5% of the total mass of the soft magnetic composite material. Controlling the mass of the binder to 1%-5% of the total mass of the soft magnetic composite material can provide sufficient bonding force to ensure that the soft magnetic composite material maintains its shape integrity during the pressing and sintering processes, while also ensuring that the soft magnetic composite material has high magnetic permeability and low eddy current loss.

[0021] In one possible embodiment, the coating layer further comprises at least one of an insulating material and a lubricant. When the coating layer contains an insulating material, it can reduce the high-frequency eddy current loss of the soft magnetic composite material and enhance the high-temperature stability of the soft magnetic composite material. When the coating layer contains a lubricant, the lubricant adsorbs on the surface of the soft magnetic powder, reducing frictional resistance between soft magnetic powder particles and between the soft magnetic powder and the mold during pressing, thereby increasing the density of the soft magnetic composite material.

[0022] Furthermore, when the coating layer comprises an insulating material, the insulating material is selected from at least one of zinc oxide, silicon dioxide, zirconium dioxide, phosphate, aluminum oxide, titanium dioxide, and magnesium oxide. These insulating materials not only have excellent insulation properties, but silicon dioxide and aluminum oxide also have high dielectric strength, making them suitable for applications in high-frequency, low-loss scenarios. Zirconium dioxide and magnesium oxide also have excellent thermal stability, which is beneficial for improving the thermal stability of soft magnetic composite materials. Zinc oxide and phosphate also have the advantage of low cost, which is conducive to the large-scale production of soft magnetic composite materials.

[0023] Furthermore, when the coating layer comprises an insulating material, the thickness of the insulating material is 10-150 nm. Controlling the thickness of the insulating material within the range of 10-150 nm can achieve a balance between loss and magnetic permeability of the soft magnetic composite material.

[0024] Furthermore, when the coating layer contains a lubricant, the lubricant is selected from at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, and graphite powder. These lubricants not only possess excellent lubrication properties, but zinc stearate also decomposes at low temperatures (120-160°C), leaving little volatile residue during the pressing process, which can reduce contamination of the soft magnetic composite material. Magnesium stearate also has low hygroscopicity, which helps reduce agglomeration of soft magnetic powders caused by moisture absorption. Calcium stearate is also biocompatible, making the soft magnetic composite material suitable for use in medical and food-grade equipment. Graphite powder has an ultra-low coefficient of friction, providing excellent lubrication.

[0025] Furthermore, when the coating layer contains a lubricant, the mass of the lubricant is 0%-1% of the total mass of the soft magnetic composite material. Controlling the mass of the lubricant within the range of 0%-1% of the total mass of the soft magnetic composite material can optimize the molding process and improve the consistency of the soft magnetic composite material product without significantly sacrificing the electromagnetic properties of the soft magnetic composite material.

[0026] In one possible embodiment, when the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder, and the pressing pressure of the soft magnetic composite material is 400-800 MPa and the heat treatment temperature is 150-250 ° C, the loss of the soft magnetic composite material under 1 MHz / 10 mT conditions is 80-120 mW / cm 3 , the loss at 1 MHz / 20 mT is 500-750 mW / cm 3 , the loss at 2 MHz / 30 mT is 2800-3800 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 25-32 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 76%-83% when the bias field is 100 Oe.

[0027] In one possible embodiment, when the soft magnetic powder is a composite of the iron-based nanocrystalline soft magnetic alloy powder and crystalline metal powder, the crystalline metal powder includes at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder, and the pressing pressure of the soft magnetic composite material is 400-800 MPa and the heat treatment temperature is 150-250 ° C, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 200-700 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 40-50 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 75%-93% when the bias field is 100 Oe.

[0028] In one possible embodiment, when the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder, the coating layer of the soft magnetic composite material contains an insulating material, and the pressing pressure of the soft magnetic composite material is 1600-2200 MPa and the heat treatment temperature is 560-620 ° C, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 250-450 mW / cm 3 , the loss at 3 MHz / 50 mT is 10000-18000 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 58-68 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 48%-58% when the bias field is 100 Oe.

[0029] In a fourth aspect, the present invention further provides a method for preparing the soft magnetic composite material, comprising the following steps:

[0030] M1: Mixing soft magnetic powder with a coating layer raw material to obtain composite magnetic powder; the soft magnetic powder is the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, or is a composite of the above-mentioned iron-based nanocrystalline soft magnetic alloy powder and crystalline metal powder, the crystalline metal powder including at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder; the coating layer raw material contains a binder, or also contains a lubricant;

[0031] M2: The composite magnetic powder is pressed and heat-treated to obtain a soft magnetic composite material, wherein the pressing pressure and the heat treatment temperature are 400-800 MPa and 150-250°C, respectively, or the pressing pressure and the heat treatment temperature are 1600-2200 MPa and 560-620°C, respectively.

[0032] The preparation method of the soft magnetic composite material provided by the present invention uses the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention as the soft magnetic powder or one of the soft magnetic powders, combines it with the binder and lubricant, and controls the pressing pressure and heat treatment temperature to obtain a soft magnetic composite material with high frequency and low loss, high magnetic permeability and high DC bias performance.

[0033] Furthermore, when the pressing pressure and heat treatment temperature in step M2 are 1600-2200 MPa and 560-620°C, respectively, the iron-based nanocrystalline soft magnetic alloy powder is an amorphous precursor powder, and the iron-based nanocrystalline soft magnetic alloy master alloy is made into the amorphous precursor powder through a multi-stage pulverization and atomization process. The multi-stage pulverization and atomization process includes four steps, namely, master alloy melting, alloy melt gas atomization, turntable mechanical atomization, and water cooling. The distance between the gas outlet in the alloy melt gas atomization and the turntable in the turntable mechanical atomization step is 110-130 mm, and the turntable speed in the turntable mechanical atomization is 6000-20000 rpm. When the amorphous precursor powder is a soft magnetic powder, it is beneficial to further improve the soft magnetic properties of the soft magnetic composite material.

[0034] Furthermore, when the raw materials for the coating layer in step M1 contain an insulating material, the insulating material is produced via a sol-gel reaction or an in-situ chemical reaction, wherein the solvent used in the sol-gel reaction or the in-situ chemical reaction is acetone or ethanol, and the reaction temperature is 40-100°C. The insulating material produced using these process conditions facilitates the formation of a more uniform and dense coating layer.

[0035] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0036] The reagents and raw materials used in the present invention are commercially available.

[0037] The positive progress effect of the present invention is:

[0038] The iron-based nanocrystalline soft magnetic alloy powder, soft magnetic composite material and preparation method thereof provided by the present invention are prepared by organically combining alloy components and powder preparation process to obtain an iron-based nanocrystalline soft magnetic alloy powder with a unique microstructure. The iron-based nanocrystalline soft magnetic alloy powder has a heterogeneous nanocrystalline structure. The heterogeneous nanocrystalline structure comprises a three-dimensional island-shaped amorphous region and a nanocrystalline region. The diameter of the three-dimensional island-shaped amorphous region is 50-100 nm, and the number density of the three-dimensional island-shaped amorphous region is between 10 19 -10 20 m -3 The nanocrystalline region includes a nanoscale α-Fe crystal phase and an amorphous matrix phase, and the iron-based nanocrystalline soft magnetic alloy powder has excellent magnetoelectric properties. The provided soft magnetic composite material has the performance advantages of high frequency and low loss, high magnetic permeability and high DC bias, among which the high-frequency loss is reduced by 20-60% compared with similar powders at home and abroad, and is very suitable for power electronic devices such as high-frequency miniaturized molded inductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 TEM image of the cross-sectional microstructure of the iron-based nanocrystalline soft magnetic alloy powder in Example 1.

[0040] Figure 2 This is the XRD diffraction pattern of the iron-based nanocrystalline soft magnetic alloy powder in Example 1.

[0041] Figure 3 This is the SEM image of the iron-based nanocrystalline soft magnetic alloy powder in Example 1.

[0042] Figure 4 This is the VSM curve of the iron-based nanocrystalline soft magnetic alloy powder in Example 1.

[0043] Figure 5 This is a data curve showing the change in power loss of the soft magnetic composite material in Example 1 as a function of the maximum working magnetic flux density.

[0044] Figure 6 This is a data curve showing the change in magnetic permeability of the soft magnetic composite material in Example 1 with frequency.

[0045] Figure 7 This is a data curve showing the change of DC bias performance of the soft magnetic composite material in Example 1 with superimposed field strength.

[0046] Figure 8 2. The SEM image and main element distribution diagram of the soft magnetic composite material in Example 8.

[0047] Figure 9Surface morphology, element distribution and cross-sectional SEM image of the iron-based nanocrystalline soft magnetic alloy powder coated with a ZnO insulating layer in Example 18. DETAILED DESCRIPTION

[0048] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0049] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0050] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments was carried out in accordance with the protocols and parameters given by the manufacturers.

[0051] In the first aspect, the present invention provides an iron-based nanocrystalline soft magnetic alloy powder, wherein the powder particles have a heterogeneous nanocrystalline structure, the heterogeneous nanocrystalline structure comprises a three-dimensional island-shaped amorphous region and a nanocrystalline region, and the diameter of the three-dimensional island-shaped amorphous region is D amo 50-100 nm, the number density of the three-dimensional island amorphous region N d, amo In 10 19 -10 20 m -3 Order of magnitude.

[0052] The iron-based nanocrystalline soft magnetic alloy powder provided by the present invention has a special inhomogeneous nanocrystalline structure. In addition to the nanocrystalline region composed of the conventional nanoscale α-Fe crystal phase and the amorphous matrix phase, the inhomogeneous nanocrystalline structure also has a three-dimensional island amorphous region. The amorphous matrix phase in the inhomogeneous nanocrystalline structure is isotropic and does not have magnetic anisotropy; the amorphous matrix phase in the nanocrystalline region has a large positive magnetostriction coefficient, while the α-Fe crystal phase has a small negative magnetostriction coefficient. When the inhomogeneous nanocrystalline structure contains a three-dimensional island amorphous region, the amorphous matrix phase and the α-Fe crystal phase can be balanced, so that the iron-based nanocrystalline soft magnetic alloy powder has a magnetostriction coefficient close to 0, reducing the remanence of the iron-based nanocrystalline soft magnetic alloy powder and increasing its magnetic permeability, which also helps the iron-based nanocrystalline soft magnetic alloy powder to obtain excellent soft magnetic properties; further combined with regulating the diameter of the three-dimensional island amorphous region in the inhomogeneous nanocrystalline structure to be 50-100 nm and the number density to be 10 19 -10 20 m -3 The invention provides an iron-based nanocrystalline soft magnetic alloy powder with a magnetostriction coefficient close to 0 to the greatest extent, and at the same time overcomes the problem of low resistivity caused by the α-Fe crystal phase, significantly improves the resistivity of the iron-based nanocrystalline soft magnetic alloy powder, and helps to reduce the high-frequency loss of the soft magnetic composite material; the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention has both excellent soft magnetic properties and high resistivity through the coordinated cooperation of the three-dimensional island-shaped amorphous region and the nanocrystalline region in the heterogeneous nanocrystalline structure.

[0053] In one possible embodiment, the average diameter of the α-Fe crystal phase in the nanocrystalline region is D cry is 8-14 nm, and the number density of α-Fe crystal phase is N d, cry In 10 22 -10 23 m -3 The general α-Fe crystal phase has magnetocrystalline anisotropy, and when the average diameter of the α-Fe crystal phase in the heterogeneous nanocrystalline structure is 8-14 nm and the number density is 10 22 -10 23 m -3 When the order of magnitude is reached, the magnetic cross-coupling between the α-Fe crystal phases can significantly reduce the magnetocrystalline anisotropy, which is beneficial to reducing the coercive force and remanence of the iron-based nanocrystalline soft magnetic alloy powder and increasing its magnetic permeability, so that the iron-based nanocrystalline soft magnetic alloy powder has excellent soft magnetic properties.

[0054] In a possible embodiment, the chemical element composition of the iron-based nanocrystalline soft magnetic alloy powder satisfies the relationship: Fe a Co b Nic Si d B e P f C g Nb h Cu i , where the subscripts a, b, c, d, e, f, g, h, and i represent the atomic percentage of each alloying element, respectively, and satisfy the following conditions: 59 ≤ a ≤ 72; 0 ≤ b ≤ 10; 0 ≤ c ≤ 5; 69 ≤ a+b+c ≤72; 12.5 ≤ d ≤ 15.5; 9 ≤ e ≤ 12; 0 ≤ f ≤ 2; 0 ≤ g ≤ 2; 3 ≤ h ≤ 5; 0.6 ≤i ≤ 0.9; a+b+c+d+e+f+g+h+i=100. The iron-based nanocrystalline soft magnetic alloy component of the above-mentioned composition has high Si, B and Nb contents, so that the alloy has good amorphous forming ability and low Cu content. Combined with the multi-stage atomization powder making process provided by the present invention, the iron-based nanocrystalline soft magnetic alloy powder with a heterogeneous nanocrystalline structure provided by the present invention can be obtained.

[0055] In one possible embodiment, the powder particles are spherical or quasi-spherical, and the average sphericity of the iron-based nanocrystalline soft coarse alloy powder is ≥0.9. Spherical powder particles have a smooth surface, few defects, low resistance to domain wall movement during magnetization, better magnetic isotropy, less pinning effect between grains, and are easy to coat, which can reduce hysteresis loss and eddy current loss between powders at high frequencies. By controlling the average sphericity of the powder particles to ≥0.9, it is beneficial to reduce the hysteresis loss and eddy current loss of the iron-based nanocrystalline soft magnetic alloy powder, improve the magnetic permeability, and reduce the coercive force.

[0056] In one possible embodiment, the iron-based nanocrystalline soft alloy powder has a saturation magnetization of 100-145 emu / g and a coercivity of less than 2 Oe. The higher saturation magnetization of the iron-based nanocrystalline soft magnetic alloy powder helps increase the power density of the soft magnetic composite material, while the lower coercivity helps reduce hysteresis losses in the soft magnetic composite material.

[0057] In a second aspect, the present invention also provides a method for preparing the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, comprising the following steps:

[0058] S1: A multi-stage pulverization and atomization process is used to prepare an amorphous precursor powder from an iron-based nanocrystalline soft magnetic alloy master alloy. The multi-stage pulverization and atomization process includes four main steps: master alloy melting, alloy melt gas atomization, rotary disk mechanical atomization, and water cooling. The distance between the gas outlet of the alloy melt gas atomization and the rotary disk of the rotary disk mechanical atomization is 110-130 mm, and the rotary disk speed of the rotary disk mechanical atomization is 6000-20000 rpm.

[0059] S2: The amorphous precursor powder in step S1 is subjected to vacuum or inert gas protection heat treatment in a rotary annealing furnace to obtain an iron-based nanocrystalline soft magnetic alloy powder. The heat treatment temperature is 560-620°C, the time is 0.5-2 hours, and the sample chamber rotation rate is 5-60 rpm.

[0060] The present invention provides a method for preparing an iron-based nanocrystalline soft magnetic alloy powder. The method adopts a multi-stage crushing and atomization process and controls key process parameters such as the distance between a gas outlet in the gas atomization stage and a turntable in a turntable mechanical atomization link and the turntable speed in a high-speed turntable mechanical atomization link, so that the iron-based nanocrystalline soft magnetic alloy can obtain a completely amorphous precursor powder and form local depletion of the Cu element therein. In a subsequent heat treatment process, the temperature and time of the heat treatment are controlled to form a three-dimensional island-shaped amorphous region in the local depletion of the Cu element and a nanocrystalline region containing an α-Fe crystal phase in the Cu element-enriched region, thereby obtaining an iron-based nanocrystalline soft magnetic alloy powder with a heterogeneous nanocrystalline structure.

[0061] In a third aspect, the present invention further provides a soft magnetic composite material comprising a soft magnetic powder and a coating layer coated on the surface of the soft magnetic powder, the coating layer comprising a binder. The soft magnetic powder is the aforementioned iron-based nanocrystalline soft magnetic alloy powder, or the soft magnetic powder is a composite of the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention and a crystalline metal powder, wherein the crystalline metal powder comprises at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder, and pure iron powder. The soft magnetic composite material exhibits excellent magnetic properties, including low loss at high frequencies, high magnetic permeability, and high DC bias performance.

[0062] In one possible embodiment, the binder is selected from at least one of epoxy resin, silicone resin, and phenolic resin. Epoxy resin has strong bonding strength with soft magnetic powder, reducing interfacial defects and improving the mechanical properties of the soft magnetic composite. Silicone resin has excellent high-temperature resistance, which helps improve the high-temperature stability of the soft magnetic composite. Phenolic resin has a cost advantage, which helps reduce the production cost of the soft magnetic composite.

[0063] In one possible embodiment, the mass of the binder is 1%-5% of the total mass of the soft magnetic composite material. Controlling the mass of the binder to 1%-5% of the total mass of the soft magnetic composite material can provide sufficient bonding force to ensure that the soft magnetic composite material maintains its shape integrity during the pressing and sintering processes, while also ensuring that the soft magnetic composite material has high magnetic permeability and low eddy current loss.

[0064] In one possible embodiment, the coating layer further comprises at least one of an insulating material and a lubricant. When the coating layer contains an insulating material, it can reduce the high-frequency eddy current loss of the soft magnetic composite material and enhance the high-temperature stability of the soft magnetic composite material. When the coating layer contains a lubricant, the lubricant adsorbs on the surface of the soft magnetic powder, reducing frictional resistance between soft magnetic powder particles and between the soft magnetic powder and the mold during pressing, thereby increasing the density of the soft magnetic composite material.

[0065] Furthermore, when the coating layer includes an insulating material, the insulating material is selected from at least one of zinc oxide, silicon dioxide, zirconium dioxide, phosphate, aluminum oxide, titanium dioxide, and magnesium oxide. These insulating materials not only have good insulation properties, but silicon dioxide and aluminum oxide also have high dielectric strength, making them suitable for applications in high-frequency, low-loss scenarios. Zirconium dioxide and magnesium oxide also have excellent thermal stability, which is beneficial for improving the thermal stability of soft magnetic composite materials. Zinc oxide and phosphate also have the advantage of low cost, which is conducive to the large-scale production of soft magnetic composite materials.

[0066] Furthermore, when the coating layer includes an insulating material, the thickness of the insulating material is 10-150 nm. Controlling the thickness of the insulating material within the range of 10-150 nm can achieve a balance between loss and magnetic permeability of the soft magnetic composite material.

[0067] Furthermore, when the coating layer includes a lubricant, the lubricant is selected from at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, and graphite powder. These lubricants not only possess excellent lubrication properties, but zinc stearate also decomposes at low temperatures (120-160°C), leaving little volatile residue during the pressing process, thus reducing contamination of the soft magnetic composite material. Magnesium stearate also has low hygroscopicity, which helps reduce agglomeration of soft magnetic powders caused by moisture absorption. Calcium stearate is also biocompatible, making the soft magnetic composite material suitable for use in medical and food-grade devices. Graphite powder has an ultra-low coefficient of friction, providing excellent lubrication.

[0068] Furthermore, when the coating layer contains a lubricant, the mass of the lubricant is 0%-1% of the total mass of the soft magnetic composite material. Controlling the mass of the lubricant within the range of 0%-1% of the total mass of the soft magnetic composite material can optimize the molding process and improve the consistency of the soft magnetic composite material product without significantly sacrificing the electromagnetic properties of the soft magnetic composite material.

[0069] In one possible embodiment, when the soft magnetic powder is the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, and the pressing pressure of the soft magnetic composite material is 400-800 MPa and the heat treatment temperature is 150-250 ° C, the loss of the soft magnetic composite material at 1 MHz / 10 mT is 80-120 mW / cm 3, the loss at 1 MHz / 20 mT is 500-750 mW / cm 3 , the loss at 2 MHz / 30 mT is 2800-3800 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 25-32 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 76%-83% when the bias field is 100 Oe.

[0070] In one possible embodiment, when the soft magnetic powder is a composite of the above-mentioned iron-based nanocrystalline soft magnetic alloy powder and crystalline metal powder, the crystalline metal powder includes at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder, and the pressing pressure of the soft magnetic composite material is 400-800 MPa and the heat treatment temperature is 150-250 ° C, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 200-700 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 40-50 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 75%-93% when the bias field is 100 Oe.

[0071] In one possible embodiment, when the soft magnetic powder is the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, the coating layer contains an insulating material, and the pressing pressure of the soft magnetic composite material is 1600-2200 MPa and the heat treatment temperature is 560-620°C, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 250-450 mW / cm 3 , the loss at 3 MHz / 50 mT is 10000-18000 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 58-68 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 48%-58% when the bias field is 100 Oe.

[0072] In a fourth aspect, the present invention further provides a method for preparing the soft magnetic composite material, comprising the following steps:

[0073] M1: Mixing soft magnetic powder with a coating layer raw material to obtain composite magnetic powder; the soft magnetic powder is the above-mentioned iron-based nanocrystalline soft magnetic alloy powder, or is a composite of the above-mentioned iron-based nanocrystalline soft magnetic alloy powder and crystalline metal powder, the crystalline metal powder including at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder; the coating layer raw material contains a binder, or also contains a lubricant;

[0074] M2: The composite magnetic powder is pressed and heat-treated to obtain a soft magnetic composite material, wherein the pressing pressure and the heat-treatment temperature are 400-800 MPa and 150-250°C, respectively, or the pressing pressure and the heat-treatment temperature are 1600-2200 MPa and 560-620°C, respectively.

[0075] The preparation method of the soft magnetic composite material provided by the present invention uses the iron-based nanocrystalline soft magnetic alloy powder provided by the present invention as the soft magnetic powder or one of the soft magnetic powders, combines it with a binder and a lubricant, and controls the pressing pressure and heat treatment temperature to obtain a soft magnetic composite material with high frequency and low loss, high magnetic permeability and high DC bias performance.

[0076] Furthermore, when the pressing pressure and heat treatment temperature in step M2 are 1600-2200 MPa and 560-620°C, respectively, the iron-based nanocrystalline soft magnetic alloy powder is an amorphous precursor powder, and the mother alloy of the iron-based nanocrystalline soft magnetic alloy is made into an amorphous precursor powder through a multi-stage pulverization and atomization process. The multi-stage pulverization and atomization process includes four main steps, namely, mother alloy melting, alloy melt gas atomization, turntable mechanical atomization, and water cooling. The distance between the gas outlet in the alloy melt gas atomization and the turntable in the turntable mechanical atomization step is 110-130 mm, and the turntable speed in the turntable mechanical atomization is 6000-20000 rpm. When the amorphous precursor powder in step S1 of the above-mentioned method for preparing iron-based nanocrystalline soft magnetic alloy powder is a soft magnetic powder, it is beneficial to further improve the soft magnetic properties of the soft magnetic composite material.

[0077] Furthermore, when the raw materials for the coating layer in step M1 contain insulating material, the insulating material is produced via a sol-gel reaction or an in-situ chemical reaction, wherein the solvent used in the sol-gel reaction or the in-situ chemical reaction is acetone or ethanol, and the reaction temperature is 40-100°C. The insulating material produced using these process conditions facilitates the formation of a more uniform and dense coating layer.

[0078] The technical solutions of the present invention are further described below with reference to specific examples. All reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment. The instruments used in the examples are also commercially available.

[0079] Examples 1-13 are examples of iron-based nanocrystalline soft magnetic alloy powders and soft magnetic composite materials using them as soft magnetic powders, Examples 14-23 are examples of soft magnetic composite materials using iron-based nanocrystalline soft magnetic alloy powders and crystalline metal powders as soft magnetic powders, and Examples 24-29 are examples of soft magnetic composite materials using iron-based nanocrystalline soft magnetic alloy powders as soft magnetic powders and having insulating materials or lubricants.

[0080] Example 1

[0081] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder, which is prepared by the following method:

[0082] S1: The atomic percentage of iron-based nanocrystalline soft magnetic alloy is Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 The master alloy was placed in a crucible of a multi-stage crushing and atomizing device, and the temperature was gradually raised to 1500 ° C. After the master alloy was completely melted, the temperature was kept for 5 minutes, the mechanical turntable and cooling water were started, and atomization was started until all the master alloy was sprayed. The atomization pressure was 4 MPa, the nozzle diameter was 3 mm, the preferred distance between the atomizing nozzle and the high-speed turntable was 120 mm, the turntable speed was 10000 rpm, and the cooling water flow rate was 12 L / min. The powder was collected from the mixture of powder and cooling water, dehydrated and dried to obtain an amorphous precursor powder.

[0083] S2: The amorphous precursor powder obtained in step S1 was subjected to vacuum rotation heat treatment to obtain Fe-based nanocrystalline soft magnetic alloy powder. The sample chamber rotation rate was 30 rpm, the heat treatment temperature was 580 °C, the heat treatment time was 1 hour, and the vacuum degree was 10 -3 Pa.

[0084] This embodiment also provides a soft magnetic composite material, which is prepared by the following method:

[0085] M1: Take an appropriate amount of the nanocrystalline soft magnetic alloy powder prepared in this embodiment and measure the particle size when the cumulative particle size distribution percentage reaches 50%. D 50 The nanocrystalline soft magnetic alloy powder was poured into the mixed solution of acetone and epoxy resin, and ultrasonication and stirring were continued. After the acetone was completely evaporated, the composite magnetic powder was obtained and dried at 100 °C for 1 hour.

[0086] M2: Take a small amount of composite magnetic powder and place it into a ring sample mold with an inner diameter of 4 mm and an outer diameter of 8 mm, respectively. The mold is placed in a hydraulic press and the composite magnetic powder is pressed into a magnetic ring at a pressure of 600 MPa. After the magnetic ring is heat treated at 200 °C for 1 hour, a soft magnetic composite material is obtained.

[0087] Example 2

[0088] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 110 mm, the turntable speed is 6000 rpm, the rotation rate of the rotary heat treatment sample chamber is 5 rpm, the heat treatment temperature is 560°C, and the heat treatment time is 1 hour. All other steps are the same as those of Example 1.

[0089] Example 3

[0090] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 130 mm, the turntable speed is 20,000 rpm, the rotation rate of the rotary heat treatment sample chamber is 60 rpm, the heat treatment temperature is 620°C, and the heat treatment time is 0.5 hour. All other steps are the same as those of Example 1.

[0091] Example 4

[0092] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 120 mm, the turntable speed is 8000 rpm, the rotation rate of the rotary heat treatment sample chamber is 20 rpm, the heat treatment temperature is 590°C, and the heat treatment time is 0.75 hours. All other steps are the same as those of Example 1.

[0093] Example 5

[0094] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 120 mm, the turntable speed is 12,000 rpm, the rotation rate of the rotary heat treatment sample chamber is 30 rpm, the heat treatment temperature is 570°C, and the heat treatment time is 1.5 hours. All other steps are the same as those of Example 1.

[0095] Example 6

[0096] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 120 mm, the turntable speed is 15,000 rpm, the rotation rate of the rotary heat treatment sample chamber is 15 rpm, the heat treatment temperature is 580°C, and the heat treatment time is 1 hour. All other steps are the same as those of Example 1.

[0097] Example 7

[0098] This example provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method differs from that of Example 1 in that the preferred distance between the atomizing nozzle and the high-speed turntable is 120 mm, the turntable speed is 10,000 rpm, the rotation rate of the rotary heat treatment sample chamber is 50 rpm, the heat treatment temperature is 590°C, and the heat treatment time is 1 hour. All other conditions are the same as those of Example 1.

[0099] Example 8

[0100] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe 69.7 Si 15.5 B 10 Nb4Cu 0.8 The rest are the same as in Example 1.

[0101] Example 9

[0102] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe 70.8 Si 13.5 B 12 Nb3Cu 0.7 The rest are the same as in Example 1.

[0103] Example 10

[0104] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe 69.6 Si 14.5 B9P2Nb4Cu 0.9 The rest are the same as in Example 1.

[0105] Example 11

[0106] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe 69.8 Si 14.5 B9C2Nb4Cu 0.7 The rest are the same as in Example 1.

[0107] Example 12

[0108] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe59.7 Co 10 Si 15.5 B 10 Nb4Cu 0.8 The rest are the same as in Example 1.

[0109] Example 13

[0110] This embodiment provides an iron-based nanocrystalline soft magnetic alloy powder and a soft magnetic composite material. The preparation method thereof is different from that of embodiment 1 in that: the atomic percentage of the iron-based nanocrystalline soft magnetic alloy is Fe 64.7 Ni5Si 15.5 B 10 Nb4Cu 0.8 The rest are the same as in Example 1.

[0111] Comparative Example 1

[0112] The iron-based nanocrystalline soft magnetic alloy powder and soft magnetic composite material provided in this comparative example are from Example 2 of patent document JP2019189928A. The microstructure of the iron-based nanocrystalline soft magnetic alloy powder is a nanocrystalline structure in which a uniform nanoscale crystal phase is distributed in an amorphous matrix.

[0113] Comparative Example 2

[0114] The iron-based nanocrystalline soft magnetic alloy powder and soft magnetic composite material provided in this comparative example are from Example 2 of patent application document JP2021086941A. The microstructure of the iron-based nanocrystalline soft magnetic alloy powder is a nanocrystalline structure in which a uniform nanoscale crystal phase is distributed in an amorphous matrix.

[0115] Comparative Example 3

[0116] The iron-based nanocrystalline soft magnetic alloy powder and soft magnetic composite material provided in this comparative example are from Example 5 of patent document WO2019031462A1. The microstructure of the iron-based nanocrystalline soft magnetic alloy powder is a nanocrystalline structure in which a uniform nanoscale crystal phase is distributed in an amorphous matrix.

[0117] The microstructure and magnetic properties of the iron-based nanocrystalline soft magnetic alloy powders prepared in Examples 1-13 and Comparative Examples 1-3 are shown in Table 1. As can be seen from the data in Table 1, the diameter of the three-dimensional island-shaped amorphous region of the iron-based nanocrystalline soft magnetic alloy powders prepared in Examples 1-3 is D amo 50-100 nm, the number density of the three-dimensional island amorphous region N d, amo In 10 19 -10 20 m -3 Order of magnitude, the average diameter of the α-Fe crystal phase D cryis 8-14 nm, and the number density of α-Fe crystal phase is N d, cry In 10 22 -10 23 m -3 The order of magnitude, while the iron-based nanocrystalline soft magnetic alloy powders in comparative examples 1-3 do not have three-dimensional island-shaped amorphous regions.

[0118] The magnetic properties of the soft magnetic composite materials prepared in Examples 1-13 and Comparative Examples 1-3 are shown in Table 2. From the data in Table 2, it can be seen that the loss of the soft magnetic composite materials prepared in Examples 1-13 under the conditions of 1 MHz / 10 mT is 85-117 mW / cm 3 , the loss at 1 MHz / 20 mT is 553-716 mW / cm 3 , the loss at 2 MHz / 30 mT is 2981-3655 mW / cm 3 The magnetic permeability of the soft magnetic composite material at 1 MHz is 26.3-30.3, and the DC bias performance of the soft magnetic composite material at a bias field of 100 Oe is 78-81%; while the loss of the soft magnetic composite material prepared in Comparative Example 1 at 1 MHz / 10 mT is 215 mW / cm 3 , which is significantly higher than the soft magnetic composite materials in Examples 1-13; the losses of the soft magnetic composite materials prepared in Comparative Examples 2 and 3 under 2 MHz / 30 mT conditions are 4796 mW / cm 3 and 3739 mW / cm 3 , which is significantly higher than the soft magnetic composite materials in Examples 1-13; and the magnetic permeability of the soft magnetic composite material prepared in Comparative Example 2 is 16.3, which is significantly lower than the soft magnetic composite materials in Examples 1-13.

[0119] Table 1 Microstructure and magnetic properties of the iron-based nanocrystalline soft magnetic alloy powders obtained in Examples 1-13 and Comparative Examples 1-3

[0120]

[0121] Table 2 Magnetic properties of the soft magnetic composite materials obtained in Examples 1-13 and Comparative Examples 1-3

[0122]

[0123] Example 14

[0124] This embodiment provides a soft magnetic composite material, which is prepared by the following method:

[0125] M1: Compound the iron-based nanocrystalline powder prepared in Example 1 with crystalline metal powder, where the crystalline metal powder is Fe50 Ni 50 (wt.%) Fe-Ni powder, crystalline metal powder D 50 The particle size of the composite powder was 3.1 μm, and the mass percentage of the crystalline metal powder in the composite powder was 30%. 2 wt% of the epoxy resin as a binder was dissolved in acetone to form a mixed solution. The composite powder was poured into the mixed solution and ultrasonicated and stirred until the acetone was completely evaporated to obtain the composite magnetic powder, which was then dried at 60 °C for 1 hour.

[0126] M2: Take the composite magnetic powder in step M1 and place it into a ring sample mold with inner and outer diameters of 4 and 8 mm, respectively. Place the ring sample mold in a hydraulic press and press the composite magnetic powder into a magnetic ring sample at a pressure of 600 MPa. Prepare 3-5 magnetic ring samples per batch and heat treat them at 200 °C for 1 hour to obtain a soft magnetic composite material.

[0127] Example 15

[0128] This embodiment provides a soft magnetic composite material, which differs from Example 14 in that the mass percentage of crystalline metal powder in the composite powder is 35%. Other aspects are the same as Example 14.

[0129] Example 16

[0130] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is iron-nickel-molybdenum powder. D 50 The particle size of the composite powder is 9.2 μm, and the mass percentage of the crystalline metal powder in the composite powder is 20%. Other steps are the same as those in Example 14.

[0131] Example 17

[0132] This embodiment provides a soft magnetic composite material. The difference from embodiment 8 is that the crystalline metal powder is iron-nickel-molybdenum powder. D 50 The other aspects are the same as those in Example 8.

[0133] Example 18

[0134] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is carbonyl iron powder. D 50 The other steps are the same as those in Example 14.

[0135] Example 19

[0136] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is carbonyl iron powder. D 50 The particle size was 4.4 μm, and the mass percentage of the crystalline metal powder in the composite powder was 40%. Other steps were the same as those in Example 14.

[0137] Example 20

[0138] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is sendust powder. D 50 The particle size of the composite powder is 7.9 μm, and the mass percentage of the crystalline metal powder in the composite powder is 25%. Other steps are the same as those in Example 14.

[0139] Example 21

[0140] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is sendust powder. D 50 The other steps are the same as those in Example 14.

[0141] Example 22

[0142] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is sendust powder. D 50 The particle size of the composite powder was 8.6 μm, and the mass percentage of the crystalline metal powder in the composite powder was 35%. Other steps were the same as those in Example 14.

[0143] Example 23

[0144] This embodiment provides a soft magnetic composite material. The difference from embodiment 14 is that the crystalline metal powder is sendust powder. D 50 The particle size of the composite powder was 8.6 μm, and the mass percentage of the crystalline metal powder in the composite powder was 40%. Other steps were the same as those in Example 14.

[0145] Table 3 shows the soft magnetic properties of the soft magnetic composite materials prepared in Examples 14-23. From the data in the table, it can be seen that the loss of the soft magnetic composite materials prepared in Examples 14-23 under the conditions of 1 MHz / 20 mT is 219-654 mW / cm 3 The magnetic permeability at 1 MHz is 41.4-48.6, and the DC bias performance of the soft magnetic composite material is 78-91% at a bias field of 100 Oe.

[0146] Table 3 Soft magnetic properties of the soft magnetic composite materials prepared in Examples 14-23

[0147]

[0148] Example 24

[0149] This embodiment provides a soft magnetic composite material containing an insulating material, which is prepared by the following method:

[0150] M1: Take an appropriate amount of the amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder in Example 1, and put it into anhydrous ethanol with 1wt.% polyvinyl pyrrolidone (PVP) in the powder, and stir it by ultrasonic dispersion for 0.5 hours to form a uniform anhydrous ethanol mixture of magnetic powder and PVP; dissolve 1.75 wt.% zinc acetate dihydrate in anhydrous ethanol, and completely dissolve it by ultrasonic dispersion, and add it dropwise to the stirring anhydrous ethanol mixture of magnetic powder and PVP, and then add 50 ml of deionized water, and adjust the pH of the mixture to 8-9 with ammonia water. Stir continuously for 5 hours in a water bath at 60°C to complete the reaction. The amorphous precursor powder after the reaction is filtered and washed 3-5 times, and then dried at 60°C for 3 hours to obtain an amorphous precursor powder coated with ZnO;

[0151] M2: Weigh 2 wt.% of epoxy resin as a binder and dissolve it in acetone. Pour the ZnO-coated amorphous precursor powder in step M1 into the mixed solution of acetone and epoxy resin. Continue ultrasonicating and stirring until the acetone is completely evaporated to obtain an amorphous precursor powder containing insulating material. Dry it at 60°C for 1 hour, then add 0.5 wt.% of zinc stearate as a lubricant to the magnetic powder and mix them evenly.

[0152] M3: Take the powder containing the insulating layer and lubricant in M2 and place it into a ring sample mold with an inner and outer diameter of 4 and 8 mm respectively. Place the ring sample mold in a hydraulic press and press it into a magnetic ring sample at a pressure of 1800 MPa; prepare 3-5 magnetic ring samples per batch and anneal them at 600 °C under vacuum for 1 hour to obtain a soft magnetic composite material containing insulating material.

[0153] Example 25

[0154] This embodiment provides a soft magnetic composite material containing an insulating material, which differs from embodiment 24 in that:

[0155] M1: Anhydrous ethanol and polyvinyl pyrrolidone are mixed in a ratio of 50:1 to form a mixed solution. The amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder prepared in Example 1 is added to the mixed solution and stirred and dispersed for 0.5 hours to obtain a magnetic powder mixture. 1 wt.% K2ZrF6 magnetic powder is dissolved in anhydrous ethanol and gradually added dropwise to the magnetic powder mixture. The pH value is then adjusted to 9-10 with NH3·H2O solution, and the mixture is reacted at 50°C for 3 hours. The reacted powder is filtered and washed 3-5 times, and then dried at 60°C for 3 hours to obtain an amorphous precursor powder coated with an insulating layer.

[0156] The rest is the same as Example 24.

[0157] Example 26

[0158] This embodiment provides a soft magnetic composite material containing an insulating material, which differs from embodiment 24 in that:

[0159] M1: 3-aminopropyltriethoxysilane (APTES) and anhydrous ethanol are mixed in a ratio of 1:125 to form a mixed solution; the amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder in Example 1 is added to the above mixed solution, and ultrasonically treated and mechanically stirred for 0.5 hours to obtain a magnetic powder mixed solution; then ammonia water is quickly dropped into the magnetic powder mixed solution, the pH value is adjusted to about 9, and mechanically stirred in a constant water bath at 50°C for 4 hours; the reacted powder is first filtered and washed with ethanol 2-4 times, and then vacuum dried at 60°C for 2 hours to obtain an amorphous precursor powder coated with an insulating layer.

[0160] The rest is the same as Example 24.

[0161] Example 27

[0162] This embodiment provides a soft magnetic composite material containing an insulating material, which differs from embodiment 24 in that:

[0163] M1: 3-Aminopropyltriethoxysilane (APTES) and anhydrous ethanol were mixed in a ratio of 1:100 to form a mixed solution. The amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder in Example 1 was added to the mixed solution, and ultrasonic treatment and mechanical stirring were performed for 0.5 hours to obtain a magnetic powder mixed solution. 6 wt.% of ethyl orthosilicate and 7 wt.% of ZrOCl2·8H2O were dissolved in deionized water and gradually added dropwise to the magnetic powder mixed solution. The pH value was then adjusted to approximately 9 with aqueous ammonia and mechanical stirring was performed in a constant water bath at 50°C for 4 hours. The reacted powder was first filtered and washed with ethanol 2-4 times, and then vacuum dried at 60°C for 2 hours to obtain an amorphous precursor powder coated with an insulating layer.

[0164] The rest is the same as Example 24.

[0165] Example 28

[0166] This embodiment provides a soft magnetic composite material containing an insulating material, which differs from embodiment 24 in that:

[0167] M1: Take the amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder in Example 1, mix it with 0.5 wt.% polyvinyl pyrrolidone (PVP) in anhydrous ethanol solution and ultrasonically stir it for 0.5 hour to obtain a magnetic powder mixture; then add 10 wt.% tetrabutyl titanate (TBOT) to the magnetic powder mixture and stir it thoroughly, then add deionized water dropwise, and mechanically stir it in a 50°C water bath for 4 hours; the reacted powder is washed with ethanol 2-3 times and filtered, and then dried at 60°C in a vacuum atmosphere for 12 hours to obtain an amorphous precursor powder coated with an insulating layer; add epoxy resin to acetone and dissolve it by ultrasonic dispersion to obtain an epoxy resin solution, the mass of the epoxy resin is 3% of the mass of the amorphous precursor powder coated with the insulating layer; then add the amorphous precursor powder coated with the insulating layer to the epoxy resin solution, stir it continuously under ultrasonic dispersion until the acetone is completely evaporated, and dry it at 60°C for 1 hour to obtain a composite magnetic powder.

[0168] The rest is the same as Example 24.

[0169] Example 29

[0170] This embodiment provides a soft magnetic composite material containing an insulating material, which differs from embodiment 24 in that:

[0171] M1: Take the amorphous precursor powder of the iron-based nanocrystalline soft magnetic alloy powder in Example 1, disperse it in a mixed solution of phosphoric acid, ethanol and deionized water, and the amount of phosphoric acid in the mixed solution is 1 wt% of the powder; ultrasonically stir it in a water bath at 50°C for 0.25 hour, mix the phosphated powder with 0.5 wt% polyvinyl pyrrolidone (PVP) in 60 ml of anhydrous ethanol solution and ultrasonically stir it for 0.5 hour, then add 20 wt% of tetrabutyl titanate (TBOT) of magnetic powder and stir it thoroughly, add deionized water drop by drop, and mechanically stir it in a water bath at 50°C for 4 hours; the reacted powder is first washed with ethanol 2-3 times and filtered, and then dried in a vacuum atmosphere at 60°C for 12 hours to obtain an amorphous precursor powder coated with an insulating layer.

[0172] The rest is the same as Example 24.

[0173] The magnetic properties of the soft magnetic composite materials containing insulating materials obtained in Examples 24-29 are shown in Table 4. As can be seen from the data in Table 4, the loss of the soft magnetic composite materials containing insulating materials obtained in Examples 24-29 at 1 MHz / 20 mT is 296-328 mW / cm 3 , the loss at 3 MHz / 50 mT is 10372-16864 mW / cm 3 , the magnetic permeability is 61.2-64, and the DC bias performance is 50-54% at a bias field of 100 Oe.

[0174] Table 4 Magnetic properties of soft magnetic composite materials containing insulating materials obtained in Examples 24-29

[0175]

[0176] The following tests were performed on the iron-based nanocrystalline soft magnetic alloy powders and soft magnetic composite materials prepared in Examples 1-13, the soft magnetic composite materials prepared in Examples 14-23, and the soft magnetic composite materials containing insulating materials prepared in Examples 24-29.

[0177] XRD test:

[0178] Using XRD powder diffractometer, the scattering from 20° to 90° θ The scanning speed is 4° / min.

[0179] Transmission electron microscope image:

[0180] The microstructure of the iron-based nanocrystalline soft magnetic alloy powder was observed using a ThemoFisher Talos F200x transmission electron microscope.

[0181] SEM images and sphericity test:

[0182] A FEI Quanta FEG 250 scanning electron microscope (SEM) was used to observe the powder's morphology, elemental distribution, cross-sectional structure, and calibrate its sphericity. SEM image processing software was used to capture the powder's outline and measure the particle's projected area (A) and perimeter (B). The sphericity formula (Φ) is: Φ = 4π*A / B^2. The average sphericity is the number-weighted average of the sphericity values ​​of all powders in the sample.

[0183] Particle size test of powder:

[0184] The particle size distribution of the powder was determined using a Sympatec HELOS-OASIS laser particle size analyzer using a dry method.

[0185] Magnetic property test of powder:

[0186] The magnetic properties of Fe-based nanocrystalline soft magnetic alloy powders were tested using a Lakeshore 7410 vibrating sample magnetometer.

[0187] Loss test of soft magnetic composite materials:

[0188] The magnetic ring sample prepared in the embodiment was wound with 20 and 5 turns of primary and secondary respectively, and the magnetic ring loss was tested using an Iwasaki 8218 AC hysteresis loop instrument.

[0189] Magnetic permeability test of soft magnetic composite materials:

[0190] Agilent 4294A was used to test the variation of magnetic permeability of soft magnetic composite materials with frequency.

[0191] DC bias performance test of soft magnetic composite materials:

[0192] The DC bias performance of soft magnetic composites was measured using a Tonghui TH28339 impedance analyzer with a DC bias power supply.

[0193] Test results description:

[0194] Figure 1 TEM image of the cross-sectional microstructure of the iron-based nanocrystalline soft magnetic alloy powder in Example 1. It can be seen from the figure that the microstructure of the iron-based nanocrystalline soft magnetic alloy powder has a heterogeneous nanocrystalline structure. The heterogeneous nanocrystalline structure is divided into a three-dimensional island-shaped amorphous region (white dotted line mark area) and a nanocrystalline region. The nanocrystalline region contains a nanoscale α-Fe crystal phase and an amorphous matrix phase. The nanoscale α-Fe crystal phase is distributed in the amorphous matrix. After measurement and calculation, the average diameter of the island-shaped amorphous region is 80 nm, and the number density is 1.6×10 20 m -3 The average diameter of the nanocrystalline phase is about 10 nm, and the number density is 2.1×10 23 m -3 .

[0195] Figure 2 The XRD diffraction pattern of the iron-based nanocrystalline soft magnetic alloy powder in Example 1 shows that the XRD pattern of the iron-based nanocrystalline soft magnetic alloy powder includes a diffuse scattering peak representing an amorphous state and a diffraction peak corresponding to an α-Fe crystal, indicating that an amorphous phase and an α-Fe crystal phase exist in the powder. Combining the TEM image and the XRD diffraction pattern, the powder microstructure is a composite structure of island-like amorphous regions and nanocrystalline regions of nanoscale α-Fe crystals distributed in an amorphous matrix. The microstructural data of the iron-based nanocrystalline soft magnetic alloy powders in Examples 1-7 are shown in Table 1.

[0196] Figure 3This is an SEM image of the iron-based nanocrystalline soft magnetic alloy powder in Example 1. It shows that the vast majority of the iron-based nanocrystalline soft magnetic alloy powder is spherical, with some being quasi-spherical or rod-shaped. The average sphericity of the iron-based nanocrystalline soft magnetic alloy powder was 0.91 after calibration. The sphericity data for the iron-based nanocrystalline soft magnetic alloy powders in Examples 1-7 are listed in Table 1.

[0197] Figure 4 The VSM curve of the iron-based nanocrystalline soft magnetic alloy powder in Example 1 is shown in the figure. It can be seen from the figure that the VSM curve of the powder is a typical soft magnetic characteristic of the type. M s and H c 125.0 emu / g and 0.8 Oe respectively.

[0198] Figure 5 The power loss of the soft magnetic composite material in Example 1 at 1 MHz frequency varies with the maximum working magnetic flux density. It can be seen from the figure that the 1 MHz / 10 mT loss of the soft magnetic composite material in Example 1 is 85 mW / cm 3 1 MHz / 20 mT loss is 553 mW / cm 3 , 2 MHz / 30 mT loss is 2981 mW / cm 3 The power loss data of the soft magnetic composite materials prepared in Examples 8-17 are listed in Table 2.

[0199] Figure 6 The graph shows the variation of the magnetic permeability of the soft magnetic composite material prepared in Example 1 with frequency. The graph shows that the magnetic permeability of the soft magnetic composite material prepared in Example 1 remains stable in the range of 1 kJ to 10 MHz, with a permeability of 30.3 at 1 MHz. The magnetic permeability data of the soft magnetic composite materials prepared in Examples 8-17 are listed in Table 2.

[0200] Figure 7 The curve below shows the DC bias performance of the soft magnetic composite material prepared in Example 1 as a function of superposition field strength. The curve shows that the DC bias performance of the soft magnetic composite material prepared in Example 1 is 80% when the DC superposition field is 100 Oe. The DC bias performance data for the soft magnetic composite materials prepared in Examples 8-17 are listed in Table 2.

[0201] Figure 8 2. The SEM image and main element distribution diagram of the soft magnetic composite material in Example 14. Figure 8 (a) is the SEM image of the interior of the soft magnetic composite material. Figure 8Figures (b), (c), and (d) show the distribution of Fe, Si, and Ni in the corresponding regions, respectively. The figures show that Si is primarily contained in the nanocrystalline soft magnetic alloy powder, while Ni is primarily distributed in the iron-nickel powder. The nanocrystalline soft magnetic alloy powder has a higher Fe content than the iron-nickel powder.

[0202] The soft magnetic properties of the soft magnetic composite materials prepared in Examples 14-23 are shown in Table 3. It can be seen from the table that the loss of the soft magnetic composite material prepared in Example 14 at 1 MHz / 20 mT is 248 mW / cm 3 , the permeability at 1 MHz is 43.6, and the DC bias performance is 86% when the bias field is 100 Oe.

[0203] Figure 9 Surface morphology, element distribution and cross-sectional SEM image of the iron-based nanocrystalline soft magnetic alloy powder coated with a ZnO insulating layer in Example 24. Figure 9 (a) shows the surface morphology of the iron-based nanocrystalline soft magnetic alloy powder coated with a ZnO insulating layer. Figure 9 (b), (c), (d) and (e) are the distribution diagrams of Fe, Si, O and Zn elements respectively. Figure 9 (f) shows a cross-sectional SEM image of an iron-based nanocrystalline soft magnetic alloy powder coated with a ZnO insulating layer. The image shows a uniform and dense ZnO layer (marked by the white dashed line) formed on the powder surface. The cross-sectional SEM image reveals an average ZnO layer thickness of approximately 110 nm.

[0204] The soft magnetic properties of the soft magnetic composite materials containing insulating materials prepared in Examples 24-29 are shown in Table 4. It can be seen from the table that the loss of the soft magnetic composite material containing insulating materials prepared in Example 24 under the conditions of 1 MHz / 20 mT is 304 mW / cm 3 , the loss at 3 MHz / 50 mT is 11520 mW / cm 3 The permeability is 62.0 at 1 MHz and the DC bias performance is 54% at a bias field of 100 Oe.

[0205] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An iron-based nanocrystalline soft magnetic alloy powder, characterized in that: The powder particles have a heterogeneous nanocrystalline structure, which includes a three-dimensional island-shaped amorphous region and a nanocrystalline region. The average diameter of the three-dimensional island-shaped amorphous region is 50-100 nm, and the number density of the three-dimensional island-shaped amorphous region is between 10 19 -10 20 m -3 The chemical element composition of the iron-based nanocrystalline soft magnetic alloy powder satisfies the relationship: Fe a Co b Ni c Si d B e P f C g Nb h Cu i , where the subscripts a, b, c, d, e, f, g, h, and i represent the atomic percentage of each alloying element, respectively, and the following conditions are met: 59 ≤ a ≤ 72; 0 ≤ b ≤ 10; 0≤ c ≤ 5; 69 ≤ a+b+c ≤ 72; 12.5 ≤ d ≤ 15.5; 9 ≤ e ≤ 12; 0 ≤ f ≤ 2; 0 ≤ g≤ 2; 3 ≤ h ≤ 5; 0.6 ≤ i ≤ 0.9; a+b+c+d+e+f+g+h+i=100.

2. The iron-based nanocrystalline soft magnetic alloy powder according to claim 1, characterized in that: The nanocrystalline region comprises a nanoscale α-Fe crystal phase and an amorphous matrix phase, wherein the average diameter of the α-Fe crystal phase is 8-14 nm, and the number density of the α-Fe crystal phase is 10 22 -10 23 m -3 Order of magnitude.

3. The iron-based nanocrystalline soft magnetic alloy powder according to claim 1, characterized in that: The powder particles are spherical or quasi-spherical in shape, and the average sphericity of the powder particles is ≥0.

9.

4. The iron-based nanocrystalline soft magnetic alloy powder according to claim 1, characterized in that: The saturation magnetization intensity of the iron-based nanocrystalline soft magnetic alloy powder is 100-145 emu / g, and the coercive force is less than 2 Oe.

5. A method for preparing the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: A multi-stage pulverization and atomization process is used to prepare an amorphous precursor powder from a master alloy of an iron-based nanocrystalline soft magnetic alloy. The multi-stage pulverization and atomization process includes four steps, namely, melting the master alloy, gas atomization of the alloy melt, mechanical atomization by a rotary disk, and water cooling. The distance between the gas outlet of the alloy melt gas atomization and the rotary disk of the rotary disk mechanical atomization step is 110-130 mm, and the rotary disk rotation speed of the rotary disk mechanical atomization step is 6000-20000 rpm. S2: using a rotary annealing furnace to perform vacuum or inert gas protection heat treatment on the amorphous precursor powder in step S1 to obtain iron-based nanocrystalline soft magnetic alloy powder, wherein the heat treatment temperature is 560-620 ° C, the time is 0.5-2 hours, and the sample chamber rotation rate is 5-60 rpm.

6. A soft magnetic composite material, characterized in that The invention comprises a soft magnetic powder and a coating layer coated on the surface of the soft magnetic powder, wherein the coating layer comprises a binder, and the soft magnetic powder is an iron-based nanocrystalline soft magnetic alloy powder as described in any one of claims 1 to 4, or the soft magnetic powder is a composite of an iron-based nanocrystalline soft magnetic alloy powder as described in any one of claims 1 to 4 and a crystalline metal powder, wherein the crystalline metal powder comprises at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder.

7. The soft magnetic composite material according to claim 6, characterized in that The binder is selected from at least one of epoxy resin, silicone resin and phenolic resin.

8. The soft magnetic composite material according to claim 6, characterized in that The mass of the binder is 1%-5% of the total mass of the soft magnetic composite material.

9. The soft magnetic composite material according to claim 6, characterized in that The coating layer further includes at least one of an insulating material and a lubricant.

10. The soft magnetic composite material according to claim 9, characterized in that When the coating layer comprises an insulating material, the insulating material is selected from at least one of zinc oxide, silicon dioxide, zirconium dioxide, phosphate, aluminum oxide, titanium dioxide and magnesium oxide.

11. The soft magnetic composite material according to claim 9, characterized in that When the coating layer comprises an insulating material, the thickness of the insulating material is 10-150 nm.

12. The soft magnetic composite material according to claim 9, characterized in that When the coating layer contains a lubricant, the lubricant is selected from at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, and graphite powder.

13. The soft magnetic composite material according to claim 12, characterized in that: When the coating layer contains a lubricant, the mass of the lubricant is 0%-1% of the total mass of the soft magnetic composite material.

14. The soft magnetic composite material according to claim 6, characterized in that When the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4, and the pressing pressure and heat treatment temperature of the soft magnetic composite material are 400-800 MPa and 150-250 ° C, respectively, the loss of the soft magnetic composite material under 1 MHz / 10 mT conditions is 80-120 mW / cm 3 , the loss at 1 MHz / 20 mT is 500-750 mW / cm 3 , the loss at 2 MHz / 30 mT is 2800-3800 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 25-32 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 76%-83% when the bias field is 100 Oe.

15. The soft magnetic composite material according to claim 6, characterized in that When the soft magnetic powder is a composite of the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4 and a crystalline metal powder, the crystalline metal powder includes at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder, and the pressing pressure and heat treatment temperature of the soft magnetic composite material are 400-800 MPa and 150-250 ° C, respectively, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 200-700 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 40-50 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 75%-93% when the bias field is 100 Oe.

16. The soft magnetic composite material according to claim 6, characterized in that When the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4, the coating layer of the soft magnetic composite material contains an insulating material, and the pressing pressure and heat treatment temperature of the soft magnetic composite material are 1600-2200 MPa and 560-620 ° C, respectively, the loss of the soft magnetic composite material under 1 MHz / 20 mT conditions is 250-450 mW / cm 3 , the loss at 3 MHz / 50 mT is 10000-18000 mW / cm 3 The magnetic permeability of the soft magnetic composite material is 58-68 at 1 MHz, and the DC bias performance of the soft magnetic composite material is 48%-58% when the bias field is 100 Oe.

17. A method for preparing the soft magnetic composite material according to any one of claims 6 to 16, characterized in that: The following steps are involved: M1: Mixing soft magnetic powder with a coating layer raw material to obtain composite magnetic powder; the soft magnetic powder is the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4, or is a composite of the iron-based nanocrystalline soft magnetic alloy powder according to any one of claims 1 to 4 and crystalline metal powder, wherein the crystalline metal powder comprises at least one of iron-nickel powder, iron-nickel-molybdenum powder, iron-silicon powder, iron-silicon-aluminum powder, iron-silicon-chromium powder, carbonyl iron powder and pure iron powder; the coating layer raw material contains a binder or a lubricant; M2: The composite magnetic powder is pressed and heat-treated to obtain a soft magnetic composite material, wherein the pressing pressure and the heat treatment temperature are 400-800 MPa and 150-250°C, respectively, or the pressing pressure and the heat treatment temperature are 1600-2200 MPa and 560-620°C, respectively.

18. The method for preparing the soft magnetic composite material according to claim 17, characterized in that: When the pressing pressure and heat treatment temperature in step M2 are 1600-2200 MPa and 560-620 ℃ respectively, the iron-based nanocrystalline soft magnetic alloy powder is an amorphous precursor powder, and the mother alloy of the iron-based nanocrystalline soft magnetic alloy is made into the amorphous precursor powder through a multi-stage crushing and atomization process. The multi-stage crushing and atomization process includes four steps in sequence, namely, mother alloy melting, alloy melt gas atomization, turntable mechanical atomization and water cooling, wherein the distance between the gas outlet in the alloy melt gas atomization and the turntable in the turntable mechanical atomization step is 110-130 mm, and the turntable speed in the turntable mechanical atomization is 6000-20000 rpm.

19. The method for preparing the soft magnetic composite material according to claim 17, characterized in that: When the raw materials of the coating layer in step M1 contain insulating material, the insulating material is generated by sol-gel reaction or chemical in-situ reaction, the solvent used in the sol-gel reaction or chemical in-situ reaction is acetone or ethanol, and the reaction temperature is 40-100°C.

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