High-frequency high-permeability nanocrystalline alloy and preparation method thereof

Abstract

The invention relates to the technical field of magnetic materials, and particularly discloses a high-frequency high-permeability nanocrystalline alloy and a preparation method thereof. The preparation method of the high-frequency high-permeability nanocrystalline alloy comprises the following steps that S1, iron powder is subjected to plasma immersion treatment to obtain enhanced iron powder, and terbium powder is subjected to laser induction treatment to obtain reconstructed terbium powder; s2, the enhanced iron powder, the reconstructed terbium powder, the silicon powder, the boron powder, the electrolytic copper powder, the niobium powder and the metal cobalt powder are added into a vacuum induction melting furnace to be smelted, and alloy liquid is obtained; s3, the smelted alloy liquid is sprayed to a copper roller rotating at a high speed at a high speed under the action of argon, and an alloy strip is prepared; and S4, the alloy strip is put into an annealing furnace with a magnetic field applying function, primary annealing and secondary annealing are carried out, and the high-frequency high-magnetic-conductivity nanocrystalline alloy can be obtained. By means of the preparation method, the magnetic conductivity and the magnetic flux density of the nanocrystalline alloy at the high frequency band are effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic materials, and more specifically, to a high-frequency and high-permeability nanocrystalline alloy and a preparation method thereof. Background Art

[0002] In the rapidly developing era of electronic information, the performance improvement and miniaturization process of electronic devices are accelerating continuously, and the demand for high-performance magnetic materials is becoming more and more urgent. As an important member of soft magnetic materials, nanocrystalline alloys have been widely used in many fields. In the field of power electronics, they are used to manufacture transformers and inductors, significantly improving the electric energy conversion efficiency; in the field of electromagnetic compatibility, the common-mode inductors made thereof effectively suppress electromagnetic interference and ensure the stable operation of electronic devices.

[0003] Traditional nanocrystalline alloys are mainly composed of elements such as iron, silicon, boron, copper, niobium, etc., and exhibit good soft magnetic properties within a certain frequency range. Generally speaking, their saturation magnetic flux density can reach 1.2 - 1.5T, and the effective permeability can reach about 80,000 at 1kHz. However, with the rapid development of electronic power devices towards high frequencies, especially in the high-frequency band above 100kHz, the performance shortcomings of traditional nanocrystalline alloys gradually become prominent. For example, at 100kHz, the effective permeability of conventional nanocrystalline alloys will drop to 30,000 - 40,000, and when the frequency increases to 500kHz, the permeability drops sharply to 10,000 - 15,000, which severely limits their further application in the high-frequency field.

[0004] At present, in order to improve the permeability of nanocrystalline alloys in the high-frequency band, the commonly used methods mainly include adjusting the alloy composition and improving the preparation process. In terms of adjusting the alloy composition, although adding a small amount of elements such as copper and niobium can refine the grains to a certain extent and improve the permeability, the effect is limited. Research shows that when the content of copper element increases from 0.5% to 1.5%, the permeability only increases by 5% - 8% at 100kHz, and adding too much of some elements will also cause the saturation magnetic flux density to decrease. In terms of improving the preparation process, the traditional melting and heat treatment processes are difficult to precisely control the microstructure of nanocrystals. For example, in the traditional vacuum melting process, it is difficult to ensure the uniformity of elements, resulting in local composition deviation and affecting the consistency of permeability; in the conventional heat treatment process, the heating rate and holding time are difficult to accurately control, making the nanocrystal grain size distribution uneven, and in the 100kHz high-frequency band, the fluctuation range of permeability can reach ±10%.

[0005] In summary, the existing nanocrystalline alloys and their preparation methods have great limitations in meeting the high-frequency application requirements. How to improve the permeability and magnetic flux density of nanocrystalline alloys in the high-frequency band has become a key technical problem to be solved urgently. This is of great significance for promoting the technological progress in fields such as high-frequency filtering electronic devices and new energy vehicles. Summary of the Invention

[0006] In order to improve the magnetic permeability and magnetic flux density of nanocrystalline alloys in the high-frequency band, the present application provides a high-frequency high-magnetic-permeability nanocrystalline alloy and a preparation method thereof.

[0007] The preparation method of the high-frequency high-magnetic-permeability nanocrystalline alloy provided by the present application adopts the following technical solution:

[0008] A preparation method of a high-frequency high-magnetic-permeability nanocrystalline alloy, comprising the following steps:

[0009] S1. After subjecting iron powder to plasma immersion treatment, enhanced iron powder is obtained, and after subjecting terbium powder to laser-induced treatment, reconstructed terbium powder is obtained;

[0010] S2. Under the condition that the vacuum degree is maintained at 1×10 -4 ~5×10 -5 Pa, the temperature is raised to 1550-1650°C at a heating rate of 15-20°C / min for melting, and after the melting is completed, a uniform alloy liquid is obtained;

[0011] S3. The molten alloy liquid is sprayed onto a high-speed rotating copper roller under the action of argon with a pressure of 10-15 kPa to form an alloy strip with a thickness of 12-30 μm;

[0012] S4. The alloy strip is placed in an annealing furnace with a magnetic field application function, first subjected to primary annealing; then subjected to secondary annealing; finally, it is cooled to room temperature with the furnace at a cooling rate of 35-55°C / min, and a high-frequency high-magnetic-permeability nanocrystalline alloy can be obtained.

[0013] By adopting the above technical solution, through the plasma immersion treatment of iron powder and the laser-induced treatment of terbium powder, the microstructure and properties of iron powder and terbium powder are changed. The plasma immersion treatment helps to change the atomic arrangement and electron structure on the surface of iron powder; the laser-induced treatment can rearrange the atoms inside terbium powder and optimize its properties. In the subsequent steps, the treated iron powder, terbium powder and other raw materials are melted, formed and annealed according to a specific process. Each step cooperates with each other. By precisely controlling parameters such as temperature, pressure and time, a uniform microstructure that is beneficial to high-frequency magnetic properties is formed inside the alloy. The iron powder after plasma immersion treatment is more conducive to refining grains, enhancing the binding force with other elements, and improving the overall stability and magnetic permeability of the alloy compared with the untreated one. The laser-induced treatment of terbium powder enables it to better play the role of regulating the magnetic properties of the alloy. Through the subsequent melting, forming and annealing processes, the prepared alloy strip has a uniform microstructure, laying a foundation for achieving high magnetic permeability and high magnetic flux density at high frequencies.

[0014] Optionally, the method for plasma immersion treatment of iron powder in S1 is as follows:

[0015] Put the iron powder into a plasma immersion ion implantation device. Under the condition of introducing a carbon ion source with a flow rate of 5 - 10 sccm, the implantation dose is 1×10 16 ~5×10 16 ions / cm 2 , the implantation energy is 30 - 50 keV, and the treatment time is 2 - 4 h.

[0016] By adopting the above technical solution, the iron powder is put into a plasma immersion ion implantation device, and a carbon ion source is introduced. Under specific implantation dose, energy and treatment time, carbon ions are accelerated under the action of an electric field and implanted on the surface of the iron powder. The implantation dose determines the number of carbon ions, the energy determines the penetration depth of the ions, and the treatment time affects the uniformity of implantation. The implantation of an appropriate amount of carbon ions changes the atomic structure and electron cloud distribution on the surface of the iron powder, thereby affecting the nucleation and growth mechanisms in the subsequent alloying process. The iron powder treated in this way can refine the grain size of the final alloy when smelting with other raw materials to form an alloy. This is because the surface structure change caused by carbon ion implantation promotes heterogeneous nucleation during the alloy solidification process, increases the nucleation rate, thereby refining the grains, and the refined grains are beneficial to improving the magnetic permeability.

[0017] Optionally, the method for laser-induced treatment of terbium powder in S1 is as follows:

[0018] Place the terbium powder in a vacuum environment with a vacuum degree of 1×10 -4 ~5×10 -4 Pa, use a pulsed laser with a wavelength of 525 - 532 nm, control the pulse width within 10 - 20 ns, and set the energy density to 0.5 - 1.5 J / cm 2 , and irradiate the terbium powder 50 - 100 times.

[0019] By adopting the above technical solution, the terbium powder is placed in a specific vacuum environment and irradiated with a pulsed laser with a specific wavelength, pulse width and energy density. The laser energy is absorbed by the terbium powder, enabling the atoms on the surface and inside of the terbium powder to obtain sufficient energy to break the original atomic arrangement and undergo rearrangement. The pulse width and the number of irradiations control the degree and range of atomic rearrangement, and the energy density determines the amount of energy obtained by the atoms. The reconstructed terbium powder after laser-induced treatment can effectively adjust the magnetic anisotropy of the alloy when smelting with other raw materials to form an alloy. The stability of the magnetic permeability of the alloy prepared using this reconstructed terbium powder is significantly improved. This is because the change in the atomic arrangement of the reconstructed terbium powder enables it to better cooperate with other elements in the alloy, optimize the magnetic domain structure, and reduce the magnetic permeability fluctuations caused by magnetic anisotropy.

[0020] Optionally, the weight parts of each raw material in S2 are: 60-75 parts of enhanced iron powder, 0.5-2 parts of reconstructed terbium powder, 8-12 parts of silicon powder, 6-9 parts of boron powder, 1-5 parts of electrolytic copper powder, 2-5 parts of niobium powder, and 1-5 parts of metallic cobalt powder.

[0021] Optionally, in S2, the enhanced iron powder, reconstructed terbium powder, metallic silicon powder, boron powder, electrolytic copper powder, niobium powder, and metallic cobalt powder are added into a vacuum induction melting furnace, and the melting time is 40-60 min.

[0022] Optionally, in S4, first, the temperature is raised at a heating rate of 10-15 °C / min to 520-560 °C, and it is kept warm for 40-50 min under a constant magnetic field of 0.6-0.8 T for primary annealing; then, the temperature is raised at a heating rate of 8-12 °C / min to 550-570 °C, and it is kept warm for 30-40 min under an alternating magnetic field of 1.2-1.5 T for secondary annealing.

[0023] By adopting the above technical solution, the primary annealing is carried out under a constant magnetic field, and the purpose is to eliminate the internal stress of the alloy strip, promote the orderly arrangement of some atoms, and form a preliminary magnetic domain structure. The secondary annealing is carried out under an alternating magnetic field, and the alternating magnetic field can further adjust the orientation and distribution of the magnetic domains, optimize the magnetic domain structure, and at the same time promote the further homogenization of the nanocrystalline grains. Different heating rates, holding temperatures, and times affect the diffusion of atoms and the adjustment degree of the magnetic domains.

[0024] The present application provides a high-frequency and high magnetic permeability nanocrystalline alloy, which is prepared by using the above preparation method.

[0025] In summary, the present application has the following beneficial effects:

[0026] 1. In the present application, iron is used as the main magnetic carrier to provide the basic magnetism for the alloy. The silicon element, by virtue of its characteristic of reducing the magnetocrystalline anisotropy, makes the magnetic domains easier to flip in the high-frequency alternating magnetic field, effectively reducing the hysteresis loss and thus improving the magnetic permeability. The boron element promotes the formation of the amorphous state, refines the grains, reduces the hindrance of the grain boundaries to the movement of the magnetic domain walls, and is beneficial to the improvement of the magnetic permeability at high frequencies. Elements such as copper, niobium, cobalt, and terbium cooperate synergistically. Copper promotes the nucleation of nanocrystals, and niobium inhibits the growth of grains. The two together refine the grains and optimize the microstructure of the alloy; cobalt enhances the magnetism, and terbium optimizes the magnetocrystalline anisotropy and enhances the magnetic coupling with other elements. By carefully designing the alloy composition, the present application enables each element to play a synergistic role, significantly improving the magnetic properties of the alloy in the high-frequency band. At a high frequency of 100 kHz, the magnetic permeability can reach more than 80,000, and at the same time, the saturation magnetic flux density is not lower than 1.3 T, successfully solving the problems of low magnetic permeability and unstable magnetic flux density of traditional nanocrystalline alloys in the high-frequency band, and meeting the requirements of high-performance magnetic materials in fields such as high-frequency filter electronic devices and new energy vehicles.

[0027] 2. This application optimizes the alloy structure at the microscopic level by subjecting iron powder to plasma immersion treatment and terbium powder to laser-induced treatment, significantly improving the high-frequency magnetic permeability. After carbon ion implantation into the iron powder, an interstitial solid solution is formed in the iron powder lattice, increasing lattice distortion and hindering dislocation movement, thereby refining the grains. Grain refinement reduces the resistance of grain boundaries to the movement of magnetic domain walls, and lattice distortion changes the electron cloud distribution, optimizing the arrangement of atomic magnetic moments. Under high-frequency alternating magnetic fields, the magnetic domain walls in the alloy are more likely to respond to magnetic field changes, reducing hysteresis loss and effectively improving the magnetic permeability. In a vacuum environment, terbium powder is irradiated with pulsed lasers, causing terbium atoms to form an ordered arrangement in the alloy microstructure and enhancing the magnetic coupling with other elements. Under high-frequency magnetic fields, good magnetic coupling helps the cooperative flipping of magnetic domains, reduces the energy loss between magnetic domains, optimizes the magnetic domain structure, reduces magnetocrystalline anisotropy, and improves the high-frequency magnetic permeability of the alloy.

[0028] 3. The method of this application involves multi-step coordination from raw material mixing to final annealing, precisely controlling the alloy microstructure to ensure stable and uniform high-frequency performance. Mixing silicon powder, etc. with laser-induced treated terbium powder by ball milling makes the raw material particles refined and uniformly mixed, laying a good foundation for subsequent melting. The annealing process includes primary annealing and secondary annealing, precisely controlling the heating rate, temperature, magnetic field, and holding time. Primary annealing eliminates stress and forms nanocrystalline nuclei, and secondary annealing further refines the grains and optimizes the magnetic domain structure under alternating magnetic fields. The entire preparation process effectively avoids the problems of element non-uniformity and uneven grain size distribution in traditional processes, making the magnetic permeability of the alloy stable in the high-frequency band above 100 kHz with a small fluctuation range, meeting the strict requirements of high-frequency applications for material performance consistency. Detailed implementation manners

[0029] The following further elaborates on this application with reference to embodiments.

[0030] Embodiment

[0031] Embodiment 1

[0032] A high-frequency and high-magnetic-permeability nanocrystalline alloy is prepared by the following method:

[0033] S1. Put iron powder into a plasma immersion ion implantation device, introduce methane with a flow rate of 5 sccm, an implantation dose of 1×10 16 ions / cm 2 , an implantation energy of 30 keV, and a treatment time of 2 h for plasma immersion treatment to obtain enhanced iron powder. Place terbium powder in a vacuum environment with a vacuum degree of 1×10 -4 Pa, use a pulsed laser with a wavelength of 525 nm, control the pulse width at 10 ns, and set the energy density at 0.5 J / cm 2, irradiate the terbium powder 50 times to obtain the reconstructed terbium powder.

[0034] S2. Weigh the raw materials according to the ratio shown in Table 1. Add the weighed enhanced iron powder, reconstructed terbium powder, silicon powder, boron powder, electrolytic copper powder, niobium powder and metallic cobalt powder into a vacuum induction melting furnace. Maintain the vacuum degree at 1×10 -4 Pa, then heat up to 1550 °C at a heating rate of 15 °C / min for melting, and the melting time is 40 min; during the melting process, first turn on the electromagnetic stirring with a frequency of 20 Hz and an intensity of 0.3 T for 15 min; then apply a pulsed magnetic field with a pulse frequency of 10 Hz and a pulse intensity of 0.5 T for 15 min. After melting, a uniform alloy liquid is obtained.

[0035] S3. Spray the melted alloy liquid onto a high-speed rotating copper roller under the action of argon with a pressure of 10 kPa. The rotation speed of the copper roller is 40 m / s to make an alloy strip with a thickness of 20 μm.

[0036] S4. Put the alloy strip into an annealing furnace with the function of applying a magnetic field. First, heat up to 520 °C at a heating rate of 10 °C / min and keep it warm for 40 min under a constant magnetic field of 0.6 T for primary annealing; then heat up to 550 °C at a heating rate of 8 °C / min and keep it warm for 30 min under an alternating magnetic field of 1.2 T for secondary annealing; finally, cool it down to room temperature with the furnace at a cooling rate of 35 °C / min to obtain a high-frequency and high-permeability nanocrystalline alloy.

[0037] Example 2

[0038] A high-frequency and high-permeability nanocrystalline alloy is prepared by the following method:

[0039] S1. Put the iron powder into a plasma immersion ion implantation device, introduce methane with a flow rate of 8 sccm, the implantation dose is 3×10 16 ions / cm 2 , the implantation energy is 40 keV, and the treatment time is 3 h for plasma immersion treatment to obtain enhanced iron powder. Place the terbium powder in a vacuum environment with a vacuum degree of 3×10 -4 Pa, use a pulsed laser with a wavelength of 528 nm, control the pulse width at 15 ns, and set the energy density to 1.0 J / cm 2 , irradiate the terbium powder 75 times to obtain the reconstructed terbium powder.

[0040] S2. Weigh the raw materials according to the ratio shown in Table 1. Add the weighed enhanced iron powder, reconstructed terbium powder, silicon powder, boron powder, electrolytic copper powder, niobium powder and metallic cobalt powder into a vacuum induction melting furnace. Maintain the vacuum degree at 3×10 -5Pa, and then the temperature is raised to 1600 °C at a heating rate of 18 °C / min for melting, and the melting time is 50 min; during the melting process, electromagnetic stirring with a frequency of 25 Hz and an intensity of 0.4 T is first turned on for 18 min; then a pulsed magnetic field is applied, the pulse frequency is 15 Hz, the pulse intensity is 0.6 T, and it lasts for 18 min. After melting, a uniform alloy liquid is obtained.

[0041] S3. Spray the melted alloy liquid onto a high-speed rotating copper roller under the action of argon with a pressure of 12 kPa. The rotational speed of the copper roller is 40 m / s to make an alloy strip with a thickness of 20 μm.

[0042] S4. Put the alloy strip into an annealing furnace with the function of applying a magnetic field. First, raise the temperature to 540 °C at a heating rate of 12 °C / min, and keep it at a constant magnetic field of 0.7 T for 45 min for primary annealing; then raise the temperature to 560 °C at a heating rate of 10 °C / min, and keep it at an alternating magnetic field of 1.3 T for 35 min for secondary annealing; finally, cool it down to room temperature with the furnace at a cooling rate of 45 °C / min to obtain a high-frequency and high-magnetic-permeability nanocrystalline alloy.

[0043] Example 3

[0044] A high-frequency and high-magnetic-permeability nanocrystalline alloy is prepared by the following method:

[0045] S1. Put iron powder into a plasma immersion ion implantation device, introduce methane with a flow rate of 10 sccm, the implantation dose is 5×10 16 ions / cm 2 , the implantation energy is 50 keV, and the processing time is 4 h for plasma immersion treatment to obtain enhanced iron powder. Put terbium powder in a vacuum environment of 5×10 -4 Pa, use a pulsed laser with a wavelength of 532 nm, control the pulse width at 20 ns, and set the energy density to 1.5 J / cm 2 , irradiate the terbium powder 100 times to obtain reconstructed terbium powder.

[0046] S2. Weigh the raw materials according to the ratio shown in Table 1. Add the weighed enhanced iron powder, reconstructed terbium powder, silicon powder, boron powder, electrolytic copper powder, niobium powder and metallic cobalt powder into a vacuum induction melting furnace, and maintain the vacuum at 5×10 -5 Pa, and then raise the temperature to 1650 °C at a heating rate of 20 °C / min for melting, and the melting time is 60 min; during the melting process, first turn on electromagnetic stirring with a frequency of 30 Hz and an intensity of 0.5 T for 20 min; then apply a pulsed magnetic field, the pulse frequency is 20 Hz, the pulse intensity is 0.8 T, and it lasts for 20 min. After melting, a uniform alloy liquid is obtained.

[0047] S3. The smelted alloy liquid is sprayed at high speed onto a high-speed rotating copper roller under the action of argon gas at a pressure of 15 kPa. The rotation speed of the copper roller is 40 m / s to produce an alloy strip with a thickness of 20 μm.

[0048] S4. Place the alloy strip in an annealing furnace with a magnetic field application function, first heat it to 560°C at a heating rate of 15°C / min, and keep it at a constant magnetic field of 0.8T for 50min for primary annealing; then heat it to 570°C at a heating rate of 12°C / min, and keep it at an alternating magnetic field of 1.5T for 40min for secondary annealing; finally cool it to room temperature with the furnace at a cooling rate of 55°C / min to obtain a high-frequency and high-permeability nanocrystalline alloy.

[0049] Example 4

[0050] A high-frequency and high-permeability nanocrystalline alloy, which is different from Example 1 in that step S2 is different. Specifically, in this embodiment, S2 includes the following steps:

[0051] The raw materials were weighed according to the ratio shown in Table 1. The weighed reinforced iron powder, reconstructed terbium powder, silicon powder, boron powder, electrolytic copper powder, niobium powder and metal cobalt powder were added into a vacuum induction melting furnace. The vacuum degree was maintained at 5×10 -5 Pa, and then heated to 1550℃ at a heating rate of 20℃ / min for melting, and the melting time was 60min; during the melting process, electromagnetic stirring with a frequency of 20Hz and an intensity of 0.5T was first turned on for 15min; then a pulsed magnetic field was applied with a pulse frequency of 20Hz and a pulse intensity of 0.5T for 20min, and a uniform alloy liquid was obtained after the melting was completed.

[0052] Table 1 Raw material ratio in Examples 1-4 (kg)

[0053] Raw materials Example 1 Example 2 Example 3 Example 4 Enhanced iron powder 60 65 70 60 Reconstructed terbium powder 0.5 1.0 1.5 0.5 Silicon powder 8 10 11 8 Boron powder 6 7 8 6 Electrolytic copper powder 1 3 4 1 Niobium powder 2 3 4 2 Metal cobalt powder 1 2 3 1

[0054] Example 5

[0055] A high-frequency and high-permeability nanocrystalline alloy, which is different from Example 1 in that step S4 is different. Specifically, in this embodiment, S4 includes the following steps:

[0056] The alloy strip was placed in an annealing furnace with a magnetic field application function, first heated to 530°C at a heating rate of 13°C / min, and kept at a constant magnetic field of 0.65T for 42min for primary annealing; then heated to 690°C at a heating rate of 9°C / min, and kept at an alternating magnetic field of 1.35T for 32min for secondary annealing; finally, cooled to room temperature with the furnace at a cooling rate of 7°C / min to obtain a high-frequency and high-permeability nanocrystalline alloy.

[0057] Example 6

[0058] A high-frequency and high-permeability nanocrystalline alloy, which is different from that in Example 1 in that: in step S2, no pulsed magnetic field is applied during the smelting process.

[0059] Comparative example

[0060] Comparative example 1

[0061] A high-frequency and high-permeability nanocrystalline alloy, which is different from that in Example 1 in that: in step S1, the iron powder is not subjected to plasma immersion treatment and the iron powder is directly used.

[0062] Comparative example 2

[0063] A high-frequency and high-permeability nanocrystalline alloy, which is different from that in Example 1 in that: in step S1, the terbium powder is not subjected to laser induction treatment, and in step S2, the untreated terbium powder is directly used.

[0064] Comparative example 3

[0065] A high-frequency and high-permeability iron-based nanocrystalline alloy is prepared according to the method of Example 1 in the patent publication text with the publication number of CN117626134A and the name of "High-frequency and high-permeability iron-based nanocrystalline alloy and its preparation method".

[0066] Comparative example 4

[0067] A high-frequency and high-permeability nanocrystalline alloy, which is different from that in Example 1 in that: in step S1, the terbium powder is not subjected to laser induction treatment, and in step S2, 0.2 kg of electrolytic copper powder, 0.2 kg of niobium powder and 0.1 kg of metallic cobalt powder are used to replace the reconstructed terbium powder, that is, the total addition amount of electrolytic copper powder is 1.2 kg, the total addition amount of niobium powder is 2.2 kg, and the total addition amount of metallic cobalt powder is 1.1 kg.

[0068] Comparative example 5

[0069] A high-frequency and high-permeability nanocrystalline alloy, which is different from that in Example 1 in that: in step S1, the terbium powder is not subjected to laser induction treatment, and in step S2, no terbium powder in any form is added.

[0070] Performance detection test

[0071] Test instrument: LakeShore7407 vibrating sample magnetometer is selected, and its frequency range can cover 10 kHz - 200 kHz, and the measurement accuracy meets the test requirements. AC power supplies with different frequencies are selected to provide stable alternating current for the magnetic property measuring instrument to ensure that the frequency output is 10 kHz and 100 kHz.

[0072] Test method: From the high-frequency and high-permeability nanocrystalline alloys prepared in Examples 1-6 and Comparative Examples 1-5, several samples with dimensions of 50 mm in length, 10 mm in width, and 20 μm in thickness (consistent with the thickness of the prepared alloy strip) were intercepted. Each sample was marked. Turn on the magnetic property measuring instrument and the AC power supply, and preheat for 30 minutes to make the instrument reach a stable working state. Calibrate the magnetic property measuring instrument using a standard sample to ensure the accuracy of the measurement results. The calibration process was carried out according to the instrument operation manual. Then, install the prepared samples on the sample fixture to ensure that the samples are firmly installed and in the correct position, and then measure the permeability and magnetic flux density of the alloy at frequencies of 10 kHz and 100 kHz respectively. The measurement results are shown in Table 2.

[0073] Table 2 Measurement Results

[0074]

[0075]

[0076] The nanocrystalline alloys prepared in Examples 1-5 showed high permeability and magnetic flux density at both 10 kHz and 100 kHz. For example, in Example 1, the permeability reached 92,000 at 10 kHz and the magnetic flux density was 1.90 T; at 100 kHz, the permeability was 89,700 and the magnetic flux density was 1.85 T. In Comparative Example 1, untreated iron powder was directly used, with a permeability of only 52,200 at 10 kHz and a magnetic flux density of 1.07 T; at 100 kHz, the permeability was 43,200 and the magnetic flux density was 0.86 T, which was much lower than that of the examples. Iron, as the main magnetic carrier, provides the basic magnetism; silicon reduces the magnetocrystalline anisotropy, making it easier for magnetic domains to flip in the high-frequency alternating magnetic field, reducing the hysteresis loss and increasing the permeability; boron promotes the formation of the amorphous state, refines the grains, and reduces the hindrance of grain boundaries to the movement of magnetic domain walls; copper promotes the nucleation of nanocrystals, and niobium inhibits grain growth. The two together refine the grains and optimize the microstructure; cobalt enhances the magnetism, and terbium optimizes the magnetocrystalline anisotropy and enhances the magnetic coupling. In Comparative Example 1, the iron powder was not treated, lacking the synergy of various elements, resulting in poor magnetic properties.

[0077] In Examples 1-3, the iron powder was subjected to plasma immersion and the terbium powder was subjected to laser-induced treatment, and finally the permeability and magnetic flux density of the nanocrystalline alloy were significantly improved. For example, in Example 1, the permeability at 100 kHz was 89,700 and the magnetic flux density was 1.85 T.

[0078] In Comparative Example 1, the iron powder was not subjected to plasma immersion treatment. The permeability at 100 kHz was 43,200, and the magnetic flux density was 0.86 T. Carbon ion implantation into the iron powder formed an interstitial solid solution, increasing lattice distortion, hindering dislocation movement, refining grains, reducing the resistance of grain boundaries to the movement of magnetic domain walls, changing the electron cloud distribution, optimizing the arrangement of atomic magnetic moments, and enhancing the permeability. In Comparative Example 1, without plasma immersion treatment, the microstructure could not be fully optimized, and the magnetic properties were limited. In Comparative Example 2, the terbium powder was not subjected to laser-induced treatment. The permeability at 100 kHz was 54,700, and the magnetic flux density was 1.03 T. Laser-induced treatment of the terbium powder made its atoms arranged orderly, enhanced magnetic coupling, optimized the magnetic domain structure, reduced magnetocrystalline anisotropy, and was beneficial to improving the stability of permeability. Therefore, in Comparative Example 2 without laser-induced treatment of the terbium powder, the permeability and magnetic flux density at high frequencies were significantly lower than those in the examples.

[0079] In Comparative Examples 4-5, when the terbium powder was not added, the permeability and magnetic flux density at 100 kHz both decreased significantly. It may be that even when electrolytic copper powder, niobium powder, and metal cobalt powder were used together to replace the reconstructed terbium powder, the permeability and magnetic flux density of the prepared alloy at 100 kHz were still poor, indicating that in the preparation process of the nanocrystalline alloy of the present application, it is very necessary to perform laser-induced treatment on the terbium powder. Otherwise, the microstructure cannot be fully optimized, and the magnetic properties of the finally prepared nanocrystalline alloy are limited.

[0080] In Example 1, under a reasonable preparation process, the magnetic properties at 10 kHz and 100 kHz were good and stable. In Example 6, no pulsed magnetic field was applied during melting. The permeability at 10 kHz was 86,500, and the magnetic flux density was 1.57 T; the permeability at 100 kHz was 82,300, and the magnetic flux density was 1.42 T, both lower than those in Example 1. The preparation process of the present application is coordinated in multiple steps from raw material mixing to annealing. During melting, the time, electromagnetic stirring, and pulsed magnetic field are controlled to ensure uniform mixing of elements, promote nucleation, and refine grains; annealing is divided into primary and secondary, and the parameters are precisely controlled to eliminate stress, form nanocrystalline nuclei, further refine grains, and optimize the magnetic domain structure. In Example 6, without applying a pulsed magnetic field, the uniformity of the alloy microstructure was affected, resulting in a decrease in magnetic properties.

[0081] The parameters of the melting steps in Example 4 were different from those in Example 1, and the parameters of the annealing steps in Example 5 were different from those in Example 1, resulting in different magnetic properties. For example, in Example 4, the permeability at 100 kHz was 87,500, and the magnetic flux density was 1.63 T; in Example 5, the permeability at 100 kHz was 85,600, and the magnetic flux density was 1.76 T, different from 89,700 and 1.85 T in Example 1. Each parameter in the preparation process has an important influence on the alloy properties. Different melting parameters affect the uniform mixing of elements and the nucleation process, and different annealing parameters affect stress elimination, grain growth, and magnetic domain structure optimization. Therefore, precise control of process parameters is the key to obtaining the best alloy properties, and reasonable adjustment can further optimize the high-frequency magnetic properties.

[0082] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art may make modifications to this embodiment that do not contribute creatively, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing a high-frequency and high-permeability nanocrystalline alloy, characterized in that, It includes the following steps: S1. After subjecting iron powder to plasma immersion treatment, enhanced iron powder is obtained; after subjecting terbium powder to laser-induced treatment, reconstructed terbium powder is obtained; S2. Under the condition that the vacuum degree is maintained at 1×10 -4 ~5×10 -5 Pa, heat up to 1550 - 1650 °C at a heating rate of 15 - 20 °C / min for melting, and after the melting is completed, obtain a uniform alloy liquid; S3. The molten alloy liquid is sprayed onto a high-speed rotating copper roller under the action of argon gas with a pressure of 10 - 15 kPa to make an alloy strip with a thickness of 12 - 30 μm; S4. The alloy strip is placed in an annealing furnace with a magnetic field application function. First, primary annealing is carried out; then secondary annealing is carried out; finally, it is cooled to room temperature in the furnace at a cooling rate of 35 - 55 °C / min to obtain a high-frequency and high-permeability nanocrystalline alloy.

2. The preparation method of a high-frequency and high-permeability nanocrystalline alloy according to claim 1, wherein The method for subjecting iron powder to plasma immersion treatment in S1 is as follows: Put iron powder into a plasma immersion ion implantation device. Under the condition of introducing a carbon ion source with a flow rate of 5 - 10 sccm, the implantation dose is 1×10 16 ~5×10 16 ions / cm 2 , the implantation energy is 30 - 50 keV, and the treatment time is 2 - 4 h.

3. The preparation method of a high-frequency and high-permeability nanocrystalline alloy according to claim 1, characterized in that The method for subjecting terbium powder to laser-induced treatment in S1 is as follows: Place terbium powder in a vacuum environment with a vacuum degree of 1×10 -4 ~5×10 -4 Pa. Use pulsed laser with a wavelength of 525 - 532 nm, control the pulse width within 10 - 20 ns, and set the energy density to 0.5 - 1.5 J / cm 2 , and irradiate the terbium powder 50 - 100 times.

4. The preparation method of a high-frequency and high-magnetic-permeability nanocrystalline alloy according to claim 1, wherein: The weight parts of each raw material in S2 are: 60 - 75 parts of enhanced iron powder, 0.5 - 2 parts of reconstructed terbium powder, 8 - 12 parts of silicon powder, 6 - 9 parts of boron powder, 1 - 5 parts of electrolytic copper powder, 2 - 5 parts of niobium powder, and 1 - 5 parts of metallic cobalt powder.

5. The preparation method of a high-frequency and high magnetic permeability nanocrystalline alloy according to claim 1, characterized in that: In S2, the enhanced iron powder, reconstructed terbium powder, metallic silicon powder, boron powder, electrolytic copper powder, niobium powder, and metallic cobalt powder are added into a vacuum induction melting furnace, and the melting time is 40 - 60 min.

6. The preparation method of a high-frequency and high magnetic permeability nanocrystalline alloy according to claim 1, characterized in that: In S4, it is first heated to 520 - 560 °C at a heating rate of 10 - 15 °C / min and kept warm for 40 - 50 min under a constant magnetic field of 0.6 - 0.8 T for primary annealing; then it is heated to 550 - 570 °C at a heating rate of 8 - 12 °C / min and kept warm for 30 - 40 min under an alternating magnetic field of 1.2 - 1.5 T for secondary annealing.

7. A high-frequency and high-permeability nanocrystalline alloy prepared by the preparation method according to any one of claims 1 - 6.

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