Fe-Co-Nb-Mo series high-frequency low-loss nanocrystalline alloy and preparation method thereof

Abstract

The invention discloses a Fe-Co-Nb-Mo series high-frequency low-loss nanocrystalline alloy and a preparation method of the Fe-Co-Nb-Mo series high-frequency low-loss nanocrystalline alloy, and belongs to the technical field of soft magnetic materials. The preparation method comprises the following steps: smelting mother alloy, preparing an amorphous strip by single-roller rapid quenching, and carrying out nanocrystalline heat treatment at 520-580 DEG C. Through composite addition of Nb and Mo and component optimization, the alloy has high saturation flux density and excellent high-frequency low-loss characteristics, the process is simple and convenient, the cost is low, and the alloy is particularly suitable for manufacturing magnetic elements such as high-frequency high-power inductors and transformers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft magnetic materials, and particularly relates to a high-saturation magnetic induction intensity, high-frequency low-loss soft magnetic material and a preparation method thereof. BACKGROUND

[0002] With the development of power electronics technology towards high frequency, miniaturization and high efficiency, higher requirements are put forward for soft magnetic materials. Nanocrystalline soft magnetic alloy has become an ideal material for manufacturing high-frequency transformers, inductors, common-mode choke coils and other magnetic components due to its high magnetic permeability, low coercivity and low high-frequency loss and other excellent comprehensive performances.

[0003] At present, the most widely used iron-based nanocrystalline alloy is mainly FINEMET type, that is, Fe81Si8.5B1.5C15Nb3Cu1 system soft magnetic alloy.

[0004] Therefore, a Chinese patent document with the publication number CN107365950B discloses an iron-based amorphous / nanocrystalline soft magnetic alloy material and a preparation and heat treatment process. The iron-based amorphous / nanocrystalline soft magnetic alloy material comprises the following component elements in percentage by mass: Fe81-83%, Si8.5-9.5%, B1.5-2%, Nb3-4.5%, Cu1-2%, Mo1-2%, Ni0-0.5% and Cr0-0.5%. The metal elements of Mo, Ni and Cr are introduced into the system to ensure better amorphous forming ability of the iron-based amorphous / nanocrystalline alloy material, and the alloy strip material with an amorphous structure is obtained through a heat treatment process. The alloy has better oxidation resistance in the strip spraying process and the heat treatment process, and helps to improve temperature consistency and reduce product performance discreteness in the heat treatment process under the atmosphere protection, has the characteristics of high heat treatment efficiency and good toughness. However, the above-mentioned disclosed soft magnetic material alloy still has the technical problems of low saturation magnetic induction intensity. Specifically, in the technical solution disclosed in the prior art, the saturation magnetic induction intensity / Bs of the FINEMET type system is usually lower than 1.35T, which limits its application in the field of pursuing high power density to some extent.

[0005] For example, the addition of W element has a high melting point and requires harsh smelting process; the addition of Al element may introduce impurities, affecting the amorphous forming ability and crystallization behavior.

[0006] Therefore, developing a novel nanocrystalline soft magnetic alloy and its preparation method that combines high saturation magnetic induction, excellent high-frequency soft magnetic properties, good thermal stability, moderate cost, and simple process has significant industrial application value. Summary of the Invention

[0007] Therefore, it is necessary to provide a solution to the technical problems of how to improve the magnetic flux density and high-frequency loss of soft magnetic materials. This invention relates to a high-frequency, low-loss nanocrystalline alloy and its preparation method.

[0008] A sort of It is a high-frequency, low-loss nanocrystalline alloy, and its composition, expressed as atomic percentage, has the following general formula: Where x, y, z, p, q, r, s are the atomic percentages of each element, and satisfy the following: 65.0 ≤ x ≤ 80.0 10.0≤y≤20.0, 1.0≤z≤3.0, 0.5≤p≤2.0, 10.0≤q≤15.0, 5.0≤r≤8.0, 0.5≤s≤1.5, And x+y+z+p+q+r+s=100.

[0009] Specifically, the aforementioned The saturation magnetic induction intensity Bs of the high-frequency, low-loss nanocrystalline alloy is ≥1.70T.

[0010] Furthermore, a method for preparing the aforementioned high flux density, high frequency, low loss nanocrystalline soft magnetic alloy includes the following steps: S1. Batching and smelting: Weigh each element pure raw material according to the atomic percentage of the general formula, and smelt it under vacuum or inert gas protection to obtain a master alloy ingot with uniform composition. S2. Preparation of amorphous ribbon: The master alloy ingot is remelted and the alloy melt is rapidly cooled into amorphous ribbon by single-roll rapid quenching method; S3. Nanocrystallization heat treatment: The amorphous ribbon is heat-treated under vacuum or inert atmosphere protection at a temperature of 520°C to 580°C for 10 to 30 minutes, followed by rapid cooling to obtain a nanocrystalline alloy ribbon.

[0011] Specifically, in step S1, the smelting process adopts vacuum induction melting or electric arc melting, and the smelting temperature is 1500℃ to 1650℃.

[0012] Specifically, in step S2, the linear velocity of the copper roller in the single-roller rapid quenching method is 30 m / s to 40 m / s.

[0013] Specifically, in step S3, the heat treatment temperature is 540°C to 560°C.

[0014] Furthermore, a nanocrystalline soft magnetic powder core, which is composed of the aforementioned The nanocrystalline alloy strip prepared by the high-frequency low-loss nanocrystalline alloy preparation method is crushed into powder, mixed with a binder, pressed into shape and cured.

[0015] Specifically, the binder is one of epoxy resin, silicone resin or phenolic resin, and the amount added is 1.0 wt% to 3.0 wt% of the weight of the alloy powder.

[0016] Specifically, the curing conditions are: heat treatment at 180°C to 220°C for 1 to 3 hours.

[0017] In summary, this invention discloses a high flux density, high frequency, and low loss magnetic flux density method. This paper describes a nanocrystalline soft magnetic alloy and its preparation method. The atomic percentage composition of this alloy is as follows: The alloy composition is defined as follows: 65.0≤x≤80.0, 10.0≤y≤20.0, 1.0≤z≤3.0, 0.5≤p≤2.0, 10.0≤q≤15.0, 5.0≤r≤8.0, 0.5≤s≤1.5, and x+y+z+p+q+r+s=100. The preparation method includes: melting the master alloy, preparing amorphous ribbons using single-roll rapid quenching, and performing nanocrystallization heat treatment at 520-580℃. This invention, through the composite addition and composition optimization of Nb and Mo, enables the alloy to simultaneously possess high saturation magnetic induction intensity (Bs≥1.70T) and excellent high-frequency, low-loss characteristics. Furthermore, the process is simple and cost-effective, making it particularly suitable for manufacturing high-frequency, high-power inductors, transformers, and other magnetic components. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] Specifically, the present invention is a It is a high-frequency, low-loss nanocrystalline alloy, and its composition, expressed as atomic percentage, has the following general formula: Where x, y, z, p, q, r, s satisfy the following relations respectively: 65.0 ≤ x ≤ 80.0 10.0≤y≤20.0, 1.0≤z≤3.0, 0.5≤p≤2.0, 10.0≤q≤15.0, 5.0≤r≤8.0, 0.5≤s≤1.5, And x+y+z+p+q+r+s=100.

[0020] A method for preparing the above-mentioned nanocrystalline soft magnetic alloy includes the following steps: (1) Batching and smelting: Weigh each element pure raw material according to the atomic percentage of the aforementioned general formula, and smelt it under vacuum or inert gas protection to obtain a master alloy ingot with uniform composition. (2) Preparation of amorphous ribbon: The master alloy ingot is remelted and the alloy melt is rapidly cooled into amorphous ribbon by single-roll rapid quenching method; (3) Nanocrystallization heat treatment: The amorphous ribbon is heat-treated under vacuum or inert atmosphere protection. The heat treatment temperature is 520°C to 580°C and the holding time is 10 to 30 minutes. Then it is rapidly cooled to room temperature to obtain nanocrystallized alloy ribbon. (4) Crushing and molding: The nanocrystalline alloy strip is crushed into powder, mixed evenly with binder, pressed and solidified to obtain nanocrystalline soft magnetic powder core products.

[0021] Specifically, the smelting in step (1) is carried out by vacuum induction smelting or electric arc smelting, and the smelting temperature is 1500℃ to 1650℃.

[0022] Specifically, the linear velocity of the copper roller in the single-roller rapid quenching method described in step (2) is 30 m / s to 40 m / s.

[0023] Specifically, the adhesive in step (4) is one of epoxy resin, silicone resin or phenolic resin, and the amount added is 1.0wt% to 3.0wt% of the weight of the alloy powder; the curing conditions are to keep warm at 180℃ to 220℃ for 1 to 3 hours.

[0024] Furthermore, the beneficial effects of the present invention are as follows: 1. High saturation magnetic induction intensity: By optimizing the Co element content, i.e. 10-20 at%, and reasonably controlling the Fe content, the saturation magnetization intensity of the alloy is significantly improved, and the Bs value can reach more than 1.7T, which is superior to the traditional FINEMET type and many existing improved alloys.

[0025] 2. Excellent high-frequency and low-loss characteristics: By using Nb and Mo in combination, and utilizing their different diffusion rates and binding characteristics with B, more uniform and finer α-Fe(Co,Si) nanocrystals are formed during heat treatment. The grain size can be controlled within 10-15 nm, and grain growth is effectively suppressed. The fine grain size and the high resistivity of the amorphous phase work together to significantly reduce the high-frequency eddy current loss of the material.

[0026] 3. Excellent thermal stability and processability: The combined addition of Nb and Mo increases the crystallization temperature and expands the heat treatment process window, making the nanocrystallization process easier to control and resulting in better product consistency. At the same time, it avoids the use of elements such as W and Al, reducing smelting difficulty and raw material costs.

[0027] 4. Simple process, suitable for industrialization: It adopts a mature single-roller rapid quenching + heat treatment process route, avoiding complex powder making processes such as gas atomization. The process is shorter, the energy consumption is lower, and it is more suitable for large-scale production.

[0028] Furthermore, the present invention will be described in further detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Example 1

[0029] S1. Formulation by atomic percentage Weigh out the pure metal and iron-boron alloy raw materials. Melt the prepared raw materials in a vacuum induction furnace at 1550℃ under argon protection, repeat the melting process three times to ensure uniform composition, and then cast them into a master alloy ingot.

[0030] S2. After crushing the master alloy ingot, place it in a quartz crucible and use a single-roller rapid quenching device under argon protection with a copper roller linear speed of 35m / s to prepare an amorphous ribbon with a width of about 2mm and a thickness of about 25μm.

[0031] S3. Place the amorphous ribbon in a vacuum heat treatment furnace and hold it at 550°C for 20 minutes, then rapidly cool it to room temperature to obtain a nanocrystalline alloy ribbon.

[0032] S4. Mechanically crush the nanocrystalline alloy strip into powder and pass it through a 200-mesh sieve. Take 100g of alloy powder and 2g of epoxy resin binder, which accounts for 2.0wt% of the powder weight, and mix them evenly. Press the mixture into a toroidal magnetic core with an outer diameter of 20mm, an inner diameter of 12mm, and a height of 5mm under a pressure of 800MPa. Finally, cure the magnetic core at 200℃ for 2 hours to obtain the final product.

[0033] The performance of the prepared nanocrystalline soft magnetic powder core was tested, and the results are as follows: a. Saturation magnetic induction (Bs): 1.72T; b. Effective permeability (μe@100kHz, 0.1V): 85; c. Loss (Pcv@100kHz, 50mT): 320kW / m³; d. Loss (Pcv@1MHz,10mT): 68mW / cm³.

[0034] Test Methodology: All performance tests above used toroidal samples. Saturation magnetic induction was measured using a DC BH loop meter under a magnetization field of 1000 A / m. Effective permeability was measured using an impedance analyzer, Keysight E4990A, at 100 kHz and 0.1 V. Power loss was measured using a high-frequency BH analyzer, IWATSUSY-8219, under specified frequency and magnetic flux density conditions. All tests complied with relevant national or international standards.

[0035] The comparison scale uses the commercial FINEMET type. The nanocrystalline alloy strip was annealed at 550°C for 30 minutes and then crushed into powder cores. The testing conditions were the same as in Example 1.

[0036] a. Saturation magnetic induction (Bs): 1.24T; b. Effective permeability (μe@100kHz, 0.1V): 65; c. Loss (Pcv@100kHz, 50mT): 380kW / m³; d. Loss (Pcv@1MHz,10mT): 125mW / cm³.

[0037] Based on the aforementioned test results, it can be seen that the alloy prepared in Example 1 of the present invention is significantly superior to the traditional FINEMET type alloy in terms of saturation magnetic induction intensity and high-frequency loss.

[0038] Specifically, the performance tests conducted on the nanocrystalline soft magnetic powder core prepared in Example 1 of the present invention and the comparative example, namely the commercial FINEMET type powder core, are described below. All tests were conducted at room temperature, i.e., 23±2°C.

[0039] 1. Saturation magnetic induction intensity / Bs test Test standards: Refer to GB / T3658-2008 "Measurement method of AC magnetic properties of soft magnetic materials ring specimens" or IEC60404-6.

[0040] Test equipment: DC BH loop measuring instrument (e.g., DCB-HAnalyzerModelSY-8232 from Iwasaki Telecommunications Co., Ltd., Japan).

[0041] Sample preparation: Take a toroidal magnetic core, such as a sample with an outer diameter of 20mm, an inner diameter of 12mm, and a height of 5mm, and wind an excitation coil, such as 100 turns, and an induction coil, such as 100 turns, evenly with enameled wire.

[0042] Test method: A sufficiently high DC magnetizing field, typically 1000 A / m, is applied to the sample to induce magnetic saturation. The change in magnetic flux density in the induction coil at this point is measured, and the saturation magnetic induction intensity Bs value is directly calculated by the instrument, with units of T.

[0043] 2. Effective permeability / μe test Test standard: Refer to GB / T11453-2013 "Test method for effective amplitude permeability of soft magnetic ferrite" or IEC62044-3.

[0044] Test equipment: Impedance analyzer, such as Keysight E4990A or equivalent.

[0045] Sample preparation: Same as Bs test sample.

[0046] Test conditions: Apply a low magnetizing field at a frequency of 100kHz, corresponding to a voltage of 0.1V, to ensure that the test is in the small-signal linear region and to avoid core saturation.

[0047] Test method: The inductance (Lx) of the magnetic core wound with the coil is measured using an impedance analyzer. The effective permeability (μe) is calculated using the following formula:

[0048] Where Lx is the measured inductance (H), le is the effective length of the magnetic circuit (m), N is the number of coil turns, Ae is the effective cross-sectional area of ​​the magnetic core (m²), and μ0 is the free permeability. .

[0049] 3. Power Loss / PVV Test Test standards: Refer to GB / T3657-2013 "Method for measuring power loss of soft magnetic materials" or IEC62044-2.

[0050] Test equipment: High-frequency power loss measurement system, such as the ACB-H Analyzer Model SY-8219 from Iwasaki Telecommunications Co., Ltd. of Japan or the Epstein Frame system from Magnet-Physik of the United States, in conjunction with a power analyzer.

[0051] Sample preparation: toroidal magnetic core sample.

[0052] Test conditions: Condition A, high magnetic flux at medium frequency: At a frequency of 100kHz, a sinusoidal excitation is applied, so that the peak magnetic flux density Bm = 50mT.

[0053] Condition B, high frequency and low magnetic flux: At a frequency of 1MHz, a sinusoidal excitation is applied so that the peak magnetic flux density Bm = 10mT.

[0054] Test method: The instrument applies a sinusoidal signal of specific frequency and voltage through an excitation coil, while simultaneously measuring the magnetic flux density (B waveform) through an induction coil. The magnetic field strength (H waveform) is obtained through integration and calculation. Power loss density, Pcv, is expressed in kW / m³ or mW / cm³; it is determined by the area of ​​the BH loop, i.e., hysteresis loss and eddy current loss, and is directly calculated and provided by the instrument. The calculation formula is essentially: (Integration over a period) Where f is the frequency, ρ is the material density, and T is the period.

[0055] In summary, this invention discloses a high flux density, high frequency, and low loss magnetic flux density method. This paper describes a nanocrystalline soft magnetic alloy and its preparation method. The atomic percentage composition of this alloy is as follows: The alloy composition is defined as follows: 65.0≤x≤80.0, 10.0≤y≤20.0, 1.0≤z≤3.0, 0.5≤p≤2.0, 10.0≤q≤15.0, 5.0≤r≤8.0, 0.5≤s≤1.5, and x+y+z+p+q+r+s=100. The preparation method includes: melting the master alloy, preparing amorphous ribbons using single-roll rapid quenching, and performing nanocrystallization heat treatment at 520-580℃. This invention, through the composite addition and composition optimization of Nb and Mo, enables the alloy to simultaneously possess high saturation magnetic induction intensity (Bs≥1.70T) and excellent high-frequency, low-loss characteristics. Furthermore, the process is simple and cost-effective, making it particularly suitable for manufacturing high-frequency, high-power inductors, transformers, and other magnetic components.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A kind It is a high-frequency, low-loss nanocrystalline alloy, characterized in that... Its composition, expressed as atomic percentage, has the following general formula: Where x, y, z, p, q, r, s are the atomic percentages of each element, and satisfy the following: 65.0≤x≤80.0， 10.0≤y≤20.0， 1.0≤z≤3.0， 0.5≤p≤2.0， 10.0≤q≤15.0， 5.0≤r≤8.0， 0.5≤s≤1.5， And x+y+z+p+q+r+s=100.

2. The one according to claim 1 It is a high-frequency, low-loss nanocrystalline alloy, characterized by: The The saturation magnetic induction intensity Bs of the high-frequency, low-loss nanocrystalline alloy is ≥1.70T.

3. A method for preparing the high flux density, high frequency, low loss nanocrystalline soft magnetic alloy as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Batching and smelting: Weigh each element pure raw material according to the atomic percentage of the general formula, and smelt it under vacuum or inert gas protection to obtain a master alloy ingot with uniform composition. S2. Preparation of amorphous ribbon: The master alloy ingot is remelted and the alloy melt is rapidly cooled into amorphous ribbon by single-roll rapid quenching method; S3. Nanocrystallization heat treatment: The amorphous ribbon is heat-treated under vacuum or inert atmosphere protection at a temperature of 520°C to 580°C for 10 to 30 minutes, followed by rapid cooling to obtain a nanocrystalline alloy ribbon.

4. The one according to claim 3 A method for preparing high-frequency, low-loss nanocrystalline alloys, characterized in that: In step S1, the smelting process adopts vacuum induction melting or electric arc melting, and the smelting temperature is 1500℃ to 1650℃.

5. The method according to claim 3 A method for preparing high-frequency, low-loss nanocrystalline alloys, characterized in that: In step S2, the linear velocity of the copper roller in the single-roller rapid quenching method is 30 m / s to 40 m / s.

6. The one according to claim 3 A method for preparing high-frequency, low-loss nanocrystalline alloys, characterized in that: In step S3, the heat treatment temperature is 540°C to 560°C.

7. A nanocrystalline soft magnetic powder core, characterized in that, One of claims 3 to 6 The nanocrystalline alloy strip prepared by the high-frequency low-loss nanocrystalline alloy preparation method is crushed into powder, mixed with a binder, pressed into shape and cured.

8. The nanocrystalline soft magnetic powder core according to claim 7, characterized in that, The binder is one of epoxy resin, silicone resin or phenolic resin, and the amount added is 1.0 wt% to 3.0 wt% of the weight of the alloy powder.

9. The nanocrystalline soft magnetic powder core according to claim 7, characterized in that, The curing conditions are: heat treatment at 180°C to 220°C for 1 to 3 hours.

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