Iron-based amorphous composite magnetically soft alloy and preparation method thereof

Abstract

The invention relates to the technical field of magnetically soft alloys, and particularly discloses an iron-based amorphous composite magnetically soft alloy and a preparation method thereof. The chemical expression of the iron-based amorphous composite soft magnetic alloy is FeaCobNicXdBePfSigYh, X is a transition metal element, Y is a rare earth element, and a, b, c, d, e, f, g and h respectively represent atomic percentage contents of corresponding chemical components; wherein 55 < = a < = 60.1, 15 < = b < = 20, 8 < = c < = 12, 6 < = d < = 9, 0.2 < = e < = 0.7, 0.01 < = f < = 0.03, 2 < = g < = 4, 2 < = h < = 4, a + b + c + d + e + f + g + h = 100, 58 < = a + 0.4b-0.2 c < = 67, 4.0 < = 2.5 e + g + 0.6 h < = 7. Reliable material support is provided for efficient, economical and sustainable operation of electrical equipment, and good market prospects and application potential are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft magnetic alloy, and particularly relates to an iron-based amorphous composite soft magnetic alloy and a preparation method thereof. BACKGROUND

[0002] With the development of modern science and technology, people's demand for high-performance magnetic materials is increasing. In electrical equipment such as motors and transformers, although traditional soft magnetic materials (such as silicon steel and ferrite materials) can meet the application requirements to a certain extent, their performance in high frequency, high temperature and harsh environment often cannot reach the ideal state. In order to improve energy efficiency and reduce energy consumption, there is an urgent need for new magnetic materials, especially soft magnetic alloys with excellent high-temperature resistance, corrosion resistance and high-frequency performance. Iron-based amorphous alloy is a soft magnetic material with excellent comprehensive performance, which has an amorphous structure, good magnetic properties and excellent mechanical properties.

[0003] However, traditional iron-based amorphous alloys are mostly designed with a single transition metal or a small amount of rare earth elements, which makes it difficult to meet the increasing application requirements of high frequency and high temperature in terms of key indicators such as magnetic permeability and saturation magnetization. At the same time, the large number of grain boundary defects in conventional crystalline alloys easily cause magnetic domain wall pinning, resulting in increased magnetic hysteresis loss. In high temperature environment, grain boundary migration easily induces microstructure degradation, which seriously restricts the high temperature stability of the material. Although existing research has tried to improve the performance of iron-based amorphous alloys by adding rare earth elements (such as Nd and Dy), the mechanism is limited to single element solid solution strengthening, and the simultaneous improvement of magnetic properties and thermal stability cannot be achieved through multi-component synergistic effect.

[0004] In terms of preparation process, traditional melting techniques (such as arc melting and ordinary induction melting) are prone to composition segregation due to insufficient cooling rate, making it difficult to effectively form an amorphous structure. In addition, contact between the melt and air can cause oxidation inclusions and element segregation, further reducing the purity and homogeneity of the alloy. In existing powder metallurgy processes, the temperature and pressure parameters are not well matched during pressing and heat treatment, resulting in insufficient inter-particle bonding strength or residual internal stress, which further affects the density and stability of the magnetic properties of the material. Therefore, it is urgent to develop an iron-based amorphous alloy material with more scientific composition design and more optimized preparation process to break through the technical bottlenecks of existing materials in terms of amorphous structure regulation, high temperature stability and low loss characteristics. SUMMARY

[0005] In view of the above problems, the present application provides an iron-based amorphous composite soft magnetic alloy and a preparation method thereof. By controlling the chemical composition and atomic ratio of the iron-based amorphous composite soft magnetic alloy, the magnetic properties of the iron-based amorphous composite soft magnetic alloy are improved, the energy consumption is reduced, and the equipment stability and environmental friendliness are enhanced.

[0006] To solve the above technical problems, the technical scheme provided by the present application is: In the first aspect, the present application provides a kind of iron-based amorphous composite soft magnetic alloy, its chemical expression is Fe a Co b Ni c X d B e P f Si g Y h X is transition metal element, Y is rare earth element, a, b, c, d, e, f, g and h respectively indicate the atomic percentage of corresponding chemical component; Wherein, 55≤a≤60.1, 15≤b≤20, 8≤c≤12, 6≤d≤9, 0.2≤e≤0.7, 0.01≤f≤0.03, 2≤g≤4, 2≤h≤4, a+b+c+d+e+f+g+h=100, 58≤a+0.4b-0.2c≤67, 4.5≤2.5e+g+0.6h≤7.5.

[0007] Compared with the prior art, the iron-based amorphous composite soft magnetic alloy (hereinafter referred to as alloy) provided by the present application, iron is the basic component of the alloy, which provides the main magnetic property and strength. As a transition metal, the magnetic property of iron is the core of the alloy, which determines the performance of the alloy. Iron has high magnetic permeability, and the arrangement of its unpaired electrons in the d orbit allows the magnetic domains to rapidly reorganize under the action of an external magnetic field, thereby rapidly generating magnetism. The electronic structure of iron and its strong exchange interaction enhance its magnetic properties, enabling the alloy to exhibit superior performance in high-frequency applications. If the iron content is insufficient, the magnetic property of the alloy will be greatly reduced, resulting in insufficient saturation magnetization and failing to meet the requirements of high-performance devices. Through extensive experiments, it has been found that an atomic percentage of iron of 55% to 60.1% can achieve a relative balance.

[0008] Cobalt improves the magnetic stability of the alloy at high temperatures, maintains the saturation magnetization, effectively reduces the magnetic hysteresis loss of the alloy, and improves the energy efficiency. By increasing the proportion of cobalt, better magnetic properties can be achieved in high-temperature environments, especially in high-performance applications of motors and transformers. Excessive cobalt content may increase the brittleness of the alloy, affecting the toughness and thus the reliability of the material under high load conditions. The existing cobalt content is generally 5% to 15%, but the present application uses other transition metals and rare earth elements, especially the assistance of ceramic nanoparticles, which makes the alloy as a whole have better toughness and anti-brittleness, thus the content of cobalt can be increased to fully utilize its role in promoting magnetism.

[0009] The addition of nickel can significantly improve the saturation magnetization of the alloy, and improve its performance under high frequency conditions. Nickel can also form a dense oxide film, improving the corrosion resistance of the alloy. Nickel can improve the ductility of the material by reducing the coercivity of the alloy, allowing the alloy to store and transfer energy more effectively in an external magnetic field, thereby reducing energy loss, especially under high frequency conditions. The content of nickel in the present application is 8%~12%, too much nickel not only increases the cost of the material, but also may cause the mechanical properties of the alloy to decrease, such as the decrease of toughness, leading to the increase of brittleness, affecting the processing performance.

[0010] Boron enhances the hardness and wear resistance of the alloy by forming iron boride compounds. Iron boride compounds form strong and tough phases in the material, improving wear resistance and impact resistance. The presence of boron can also effectively improve the amorphous forming ability of the alloy, enhancing the structural stability of the material. The content of boron is 0.2%~0.7%, too high content will cause the alloy to be brittle, affecting the toughness.

[0011] The addition of phosphorus can improve the flowability and processability of the alloy. Phosphorus can reduce the melting point of the alloy in the molten state, improving the flowability of the alloy, thereby facilitating the casting and forming process. Although phosphorus helps to improve flowability, excessive phosphorus will introduce brittleness, affecting the toughness of the material. The content of phosphorus is 0.01%~0.03%, which can ensure its improvement of flowability without affecting the overall performance of the material.

[0012] The addition of silicon can improve the oxidation resistance and corrosion resistance of the alloy. Silicon can form silicate compounds in the alloy, enhancing the oxide film of the alloy and improving the corrosion resistance. The presence of silicon helps to stabilize the structure of the iron-based alloy and reduces the oxidation rate at high temperatures. The content of silicon is 2%~4%, too high silicon content will affect the magnetic properties of the alloy.

[0013] Preferably, X is selected from at least two of Cr, Mn, Mo, Ti or V.

[0014] Further preferably, the atomic percentage content of Cr is 1%~4%, more preferably 2.5%~3.4%.

[0015] Further preferably, the atomic percentage content of Mn is 1%~3%, more preferably 2%~3%.

[0016] Further preferably, the atomic percentage content of Mo is 1%~6%, more preferably 2%~4%.

[0017] Further preferably, the atomic percentage content of Ti is 1%~3%, more preferably 2%~3%.

[0018] Further preferably, the atomic percentage content of V is 0.1%~3%, more preferably 1%~2.3%.

[0019] The preferred transition metal elements in the present application can meet different performance bias requirements, further improving the comprehensive performance of the iron-based amorphous composite soft magnetic alloy. It should be noted that when X is selected from 2 to 5 of Cr, Mn, Mo, Ti or V, Cr, Mn, Mo, Ti and V are all taken from the above range.

[0020] Chromium can improve the oxidation resistance and corrosion resistance of the alloy. Chromium forms a dense oxide film on the surface of the alloy, effectively isolating the metal matrix from the external environment and preventing the intrusion of oxygen and moisture. The oxide film has the ability to self-repair, allowing the alloy to maintain a low corrosion rate in high-temperature and humid environments. The chromium content is limited to 1% to 4%, and excessive chromium will affect the plasticity of the alloy.

[0021] Manganese can enhance the toughness and oxidation resistance of the alloy. A specific amount of manganese can form a strong and tough solid solution, which can help stabilize the microstructure of the alloy, reduce the brittleness caused by phase transformation, and improve the strength and plasticity of the alloy.

[0022] Molybdenum enhances the hardness, tensile strength and wear resistance of the alloy through solid solution strengthening. Molybdenum can form a stable solid solution with iron, thereby improving the overall strength. Molybdenum also improves the stability of the alloy at high temperatures, reducing performance degradation caused by thermal stress. The molybdenum content is 1% to 6%, and excessive molybdenum will affect the magnetic properties.

[0023] Titanium can form compounds such as TiC, enhancing the hardness of the alloy while providing good strength and wear resistance. A specific amount of titanium can effectively inhibit grain growth, thereby improving the high-temperature performance of the alloy.

[0024] A specific amount of vanadium can form a solid solution strengthening effect, enhancing the tensile strength, hardness and toughness of the alloy, and also improving the heat resistance of the alloy to ensure its stable performance in high-temperature environments.

[0025] Preferably, Y is selected from at least two of La, Nd or Sm.

[0026] Further preferably, the atomic percentage of La is 1% to 2%.

[0027] Further preferably, the atomic percentage of Nd is 1% to 2%.

[0028] Further preferably, the atomic percentage of Sm is 1% to 2%, more preferably 1% to 1.5%.

[0029] Rare earth elements play an important role in iron-based amorphous composite soft magnetic alloys, as they not only enhance the magnetic properties of the alloy but also improve its thermal stability and mechanical properties. It should be noted that when Y is selected from 2 to 3 of La, Nd or Sm, La, Nd and Sm are all taken from the above range.

[0030] Lanthanum can enhance the wear resistance and oxidation resistance of the alloy. The presence of lanthanum can improve the microstructure of the alloy, improve the overall strength and toughness. Lanthanum can promote the formation of oxides in the alloy, provide better corrosion resistance, and prolong the service life of the alloy. The content of lanthanum is 1%~2%, excessive amount will increase the cost and cause brittleness problem.

[0031] Neodymium can significantly improve the magnetic properties and energy density of the alloy. Neodymium has a high magnetic moment, which can effectively increase the saturation magnetization of the alloy. This makes the alloy still maintain good magnetism under high frequency and high temperature conditions. The f orbit electrons of neodymium interact with the d orbit electrons, enhancing the overall magnetism of the alloy, making it perform superior in various applications. The content of neodymium is 1%~2%, excessive content will lead to cost increase and brittleness problem of the alloy.

[0032] Samarium can improve the high temperature stability and magnetic properties of the alloy. The addition of samarium helps to optimize the magnetic anisotropy of the alloy, so that it maintains a high saturation magnetization at high temperature. The combination of samarium and iron forms a strong magnetic phase, enhancing the thermal stability of the alloy and reducing performance degradation at high temperature. The content of samarium is 1%~2%, excessive amount will introduce unnecessary brittleness.

[0033] Preferably, 60≤a+0.4b-0.2c≤65.

[0034] Preferably, 5≤2.5e+g+0.6h≤7.

[0035] Test results show that the coercive force of the iron-based amorphous composite soft magnetic alloy provided by the application is 4.0A / m~5.0A / m, the resistivity is 120µΩ·cm~140µΩ·cm, the saturation magnetic induction intensity is 1.6T~1.9T, and the high-frequency magnetic hysteresis loss is 15W / kg~25W / kg.

[0036] In the second aspect, the application provides a preparation method of the iron-based amorphous composite soft magnetic alloy, comprising the following steps: S100, according to the atomic percentage, the alloy raw materials are weighed, the alloy raw materials except rare earth elements and ceramic nanoparticles are put into a vacuum induction melting furnace, and the mother alloy ingot is obtained by melting under a protective atmosphere; S200, the mother alloy ingot is subjected to secondary melting under a protective atmosphere, then the alloy raw material containing rare earth elements is added to the molten alloy, and the soft magnetic alloy particles are obtained by spray cooling; S300, the soft magnetic alloy particles are pressed at 500℃~800℃ under a protective atmosphere, and then subjected to step-by-step heat treatment at 300℃~350℃, 370℃~430℃ and 450℃~500℃, respectively, while an alternating magnetic field is applied; then rolled into a shape to obtain the iron-based amorphous composite soft magnetic alloy.

[0037] The preparation method of the iron-based amorphous composite soft magnetic alloy provided by the present application improves the overall performance by improving the mechanical properties, wear resistance and thermal stability of the alloy through ceramic nanoparticles. The ceramic nanoparticles significantly improve the hardness of the alloy by forming a strengthening phase in the alloy. The nanoparticles can hinder the movement of dislocations, thereby improving the wear resistance of the material. The introduction of ceramic nanoparticles can effectively improve the thermal stability of the alloy, so that it maintains good mechanical properties at high temperatures. The ceramic particles can be dispersed in the metal matrix, reducing thermal stress concentration and reducing the occurrence of thermal fatigue. The refinement of ceramic nanoparticles can improve the microstructure of the alloy and enhance the overall toughness. Under high strength conditions, the presence of nanoparticles helps to resist fracture and damage, improving the impact resistance of the material. The size of the ceramic nanoparticles is usually in the nanometer range, and this small size allows the particles to be uniformly dispersed in the alloy, making it difficult to form macroscopic defects or phase changes. This uniform distribution helps to enhance the hardness and toughness of the alloy without adversely affecting the magnetic properties. Ceramic nanoparticles are usually non-magnetic materials, and their introduction does not increase the magnetic resistance of the alloy; on the contrary, they act as a strengthening phase in the alloy, improving hardness and wear resistance without interfering with the electron arrangement of the magnetic components. In addition, the melting point of ceramic nanoparticles is much higher than that of the alloy raw materials, and they will not melt during the smelting process, thereby ensuring that the alloy maintains its properties at high temperatures. At the same time, ceramic nanoparticles can improve the flowability of the melt and reduce viscosity, thereby improving the formability and processing performance of the material. Ceramic nanoparticles can also effectively suppress eddy current loss, especially in high-frequency applications, reducing the overall magnetic loss of the material, making the alloy superior in electromagnetic performance.

[0038] The spray cooling process can quickly cool the molten alloy, thereby forming an amorphous structure. This structure has lower grain boundaries than traditional crystalline alloys, providing better magnetic permeability and lower magnetic loss, demonstrating the creativity of advanced material design. The present application can make the soft magnetic alloy particles have good adhesion through high temperature pressing, and eliminate internal stress through reasonable heat treatment. The use of a staged annealing process with alternating magnetic fields can further optimize the soft magnetic properties of the alloy and reduce hysteresis loss.

[0039] Preferably, in S100, the purity of the alloy raw material is ≥ 99%. Industrial-grade or high-purity alloy powder is preferred.

[0040] Preferably, in S100, the mass ratio of the alloy raw material to ceramic nanoparticles is 100:(0.05~0.1).

[0041] The present application limits the amount of ceramic nanoparticles to ensure that the mechanical properties are enhanced without occupying too much of the iron-based and transition metal elements of the alloy, and the core magnetic components of the alloy still dominate.

[0042] In an example, the ceramic nanoparticles in S100 include at least one of silicon nitride, aluminum oxide, silicon carbide, or zirconium oxide.

[0043] Preferably, in S100, the temperature of the melting is 1400℃-1600℃, the absolute pressure is ≤9×10 -3 Pa, and the melting time is 10min-30min.

[0044] During the melting process, the melting point of the ceramic nanoparticles is much higher than that of the alloy raw materials, so the ceramic nanoparticles will not melt during the melting process, thereby ensuring that the alloy maintains its properties at high temperatures. In addition, the ceramic nanoparticles can improve the flowability of the melt and reduce the viscosity. During the melting process, the temperature and vacuum degree in the furnace need to be checked regularly to ensure the stability of the melting environment.

[0045] In an example, S100 further includes cooling to room temperature, crushing, and cleaning to remove surface impurities after the melting is completed, thereby obtaining a master alloy ingot.

[0046] In an example, the protective atmosphere includes at least one of nitrogen or argon.

[0047] Preferably, in S200, the temperature of the secondary melting is 1400℃-1600℃, the absolute pressure is ≤9×10 -3 Pa, and the secondary melting time is 7min-10min.

[0048] In an example, S200 further includes performing the secondary melting under electromagnetic stirring after the master alloy ingot is completely melted, so as to ensure uniformity of the components. During the electromagnetic stirring process, the gas flow is kept stable to avoid the formation of bubbles or inclusions.

[0049] Preferably, in S200, the ultrasonic treatment is further included after the rare earth element-containing alloy raw material is added to the molten alloy and before the spray cooling.

[0050] Further preferably, in S200, the ultrasonic treatment has a temperature above the liquidus temperature of the metal, a frequency of 15kHz-40kHz, a power density of 100W / cm 2 -1000W / cm 2 , and an ultrasonic time of 3min-30min.

[0051] The present application reduces bubbles and inclusions in the molten alloy by the ultrasonic treatment, thereby further improving the quality of the soft magnetic alloy particles after cooling.

[0052] Preferably, in S200, the cooling rate of the spray cooling is ≥10 3 ℃ / s.

[0053] In an example, in S200, the spray cooling is performed in a protective atmosphere (e.g., argon) to avoid direct exposure of the soft magnetic alloy particles to air.

[0054] Preferably, in S200, the soft magnetic alloy particles have a micron-level particle size.

[0055] Preferably, in S200, after the spray cooling, the method further comprises: placing the soft magnetic alloy particles into a plasma processing device with an absolute pressure of ≤ 9 × 10 -3 Pa, introducing a rare gas, turning on a power supply to perform plasma processing, and then drying.

[0056] The plasma activates the surface of the soft magnetic alloy particles. Under the action of the plasma, the oxides and other impurities on the surface of the soft magnetic alloy particles are gradually stripped. At the same time, the surface is slightly etched. The rare gas plasma reacts with active sites on the surface of the soft magnetic alloy particles to form a dense passivation layer, thereby preventing further oxidation and impurity adsorption. The passivation layer is usually thin and does not affect the overall performance of the alloy, but can significantly improve the surface stability. The vacuum condition can ensure that oxygen and other contaminants are removed, reducing the influence of impurities in the air. Drying can further prevent recrystallization of the soft magnetic alloy particles.

[0057] In an example, in S200, the rare gas includes at least one of argon, helium, or neon. The present application does not have a requirement for the amount of rare gas introduced, and can achieve the excitation condition of the plasma, such as a gas pressure of 400 Pa to 800 Pa.

[0058] Further preferably, in S200, the plasma processing time is 5 min to 60 min.

[0059] Further preferably, in S200, the drying temperature is 40°C to 60°C.

[0060] Preferably, in S300, the pressing temperature is 600°C to 700°C, the pressure is 500 MPa to 1000 MPa, and the holding time is 30 min to 120 min.

[0061] During the pressing process, it is necessary to ensure uniform pressure to avoid local overpressure or underpressure. After the pressing is completed, the pressure is slowly reduced and naturally cooled to room temperature. During the cooling process, avoid sharp temperature changes to prevent material cracking or deformation.

[0062] Preferably, in S300, the time for each stage of the staged heat treatment is 1 h to 1.5 h.

[0063] Preferably, in S300, the strength of the alternating magnetic field is 10Oe~1000Oe (further preferably 100Oe~500Oe), and the frequency is 1Hz~100Hz (further preferably 30Hz~70Hz).

[0064] It is found through a large number of experiments that a magnetic field with too low strength cannot produce obvious effects, and a magnetic field with too high strength will cause overheating. The use of a low-frequency alternating magnetic field with a frequency of 1Hz~100Hz can avoid material damage and ensure the optimization of magnetic properties. The alternating magnetic field should be consistent with the main magnetization direction of the soft magnetic alloy particles to ensure uniform distribution of the magnetization process and avoid local uneven magnetization.

[0065] The present application can help control the ratio of amorphous phase and nanocrystalline phase and make the microstructure more uniform, thereby improving the magnetic properties, by applying different alternating magnetic fields at different time points. When the temperature reaches the target heat treatment temperature (300℃~500℃), an alternating magnetic field with a low strength of 10Oe~100Oe is first applied when the temperature rises to 150℃~200℃, which helps guide the directional arrangement of magnetic domains during the initial growth stage of the grains and reduces the interference of magnetic domain walls. When the heat treatment temperature reaches the target value (300℃~500℃) and is maintained for 1h, the alternating magnetic field strength is gradually increased to 100Oe~500Oe, which can help further optimize the arrangement of magnetic domains and reduce internal stress. After the end of the staged heat treatment, a low-strength alternating magnetic field of 10Oe~100Oe is applied as the temperature gradually decreases to 150℃~200℃, which can ensure the stability of the magnetic domain structure during the cooling process and avoid the re-initiation of domain wall dislocation by annealing stress. In addition, the application of the alternating magnetic field can be divided into several cycles, each cycle being separated by 5min~10min to maximize the adjustment effect on the magnetic domains at different time points; the duration of each stage of the alternating magnetic field is adjusted according to the site conditions, and generally lasts for 10min~30min to ensure that the magnetic properties are optimized.

[0066] Preferably, in S300, the rolling forming is performed by a multi-pass cold rolling method.

[0067] Further preferably, in S300, the thickness reduction of each pass of the multi-pass cold rolling is 5%~10%.

[0068] Preferably, the thickness reduction of each pass can reduce the introduction of material hardening and internal stress.

[0069] Preferably, in S300, after the rolling forming, annealing at 300℃~500℃ is further included to eliminate stress and restore plasticity.

[0070] The present application has the following beneficial effects: The present application optimizes the chemical composition of the iron-based alloy by combining multiple transition metals and rare earth elements. This diversified design not only enhances the magnetic properties but also improves the high-temperature resistance and stability of the alloy.

[0071] Vacuum induction melting and electromagnetic stirring techniques are employed to ensure the uniformity and purity of the alloy composition, thereby enhancing the overall performance of the alloy. Compared to traditional melting processes, these techniques significantly reduce inclusions and oxidation, enhancing the consistency and reliability of the material.

[0072] During the heat treatment process, the alternating magnetic field effectively releases internal residual stress in the material, avoiding the formation of internal stress during grain growth, which helps to improve the permeability of the soft magnetic alloy and reduce hysteresis loss. The alternating magnetic field can promote the movement of magnetic domain walls, thereby reducing the interaction force and energy dissipation between magnetic domain walls. This effect can significantly reduce hysteresis loss and make the magnetization process smoother. BRIEF DESCRIPTION OF DRAWINGS

[0073] Fig. 1 Figure 1 is the hysteresis loop diagram of the iron-based amorphous composite soft magnetic alloy in Example 1 of the present application; Fig. 2 Figure 2 is the dynamic magnetization curve diagram of the iron-based amorphous composite soft magnetic alloy in Example 1 of the present application; Fig. 3 Figure 3 is the loss characteristic curve diagram of the iron-based amorphous composite soft magnetic alloy in Example 1 of the present application; Fig. 4 Figure 4 is the X-ray diffraction diagram of the iron-based amorphous composite soft magnetic alloy in Example 1 of the present application. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the following combined with examples, the present application is further described in detail. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0075] Unless otherwise specified, all products are commercially available.

[0076] Example 1 This embodiment provides an iron-based amorphous composite soft magnetic alloy, the chemical composition and atomic ratio are shown in Table 1.

[0077] The preparation method of the above-mentioned iron-based amorphous composite soft magnetic alloy includes the following steps: S100, according to the atomic percentage design, weigh each alloy raw material, the purity of each alloy raw material is ≥99%, put the alloy raw materials and ceramic nanoparticles except rare earth elements into a vacuum induction melting furnace, the mass ratio of alloy raw materials and ceramic nanoparticles is 100:0.07, under the protection of atmosphere at 1500℃, 8x10-3 After smelting for 20 min at Pa, the alloy ingot was cooled to room temperature, crushed and washed to obtain a master alloy ingot.

[0078] S201, under a protective atmosphere, the master alloy ingot was placed in a vacuum induction melting furnace and smelted at 1500℃, 8×10 -3 Pa for the second time. After the master alloy ingot was completely melted, the smelting was continued for 8 min under the action of electromagnetic stirring. Then, alloy raw materials containing rare earth elements were added to the molten alloy, an ultrasonic transducer was immersed in the molten alloy, and ultrasonic treatment was performed at a frequency of 30 kHz and a power of 500 W / cm 2 for 15 min at a temperature above the liquidus of the metal. After the ultrasonic treatment, the molten alloy was sprayed and cooled (the molten alloy was sprayed through a high-pressure nozzle to form fine droplets, and the cooling rate was 1.8×10 3 ℃ / s) to obtain micron-sized soft magnetic alloy particles.

[0079] S202, the soft magnetic alloy particles were placed in the vacuum chamber of a plasma treatment device, vacuumed to 8×10 -3 Pa, and then argon was introduced. The high-frequency power was turned on to excite the argon in the vacuum chamber to form a plasma. After 10 min of plasma treatment, the plasma source was turned off, nitrogen was slowly introduced into the vacuum chamber, and the gas pressure was gradually restored. The plasma-treated soft magnetic alloy particles were taken out and dried at 50℃.

[0080] S301, under a protective atmosphere, the dried soft magnetic alloy particles were loaded into a mold, and pressed at 600℃ and a pressure of 800 MPa for 90 min. The pressure was slowly reduced and naturally cooled to room temperature to obtain a soft magnetic alloy block.

[0081] S302, under a protective atmosphere, the soft magnetic alloy block was sequentially subjected to staged heat treatment at 300℃, 400℃ and 500℃, with each stage of treatment lasting for 1 h. At the same time, an alternating magnetic field was applied in the same direction as the main magnetization direction of the soft magnetic alloy particles.

[0082] When the temperature rose to 170℃, a low-intensity alternating magnetic field of 50 Oe was first applied. When the heat treatment temperature reached the target value (300℃-500℃) and was maintained for 1 h, the alternating magnetic field intensity was gradually increased to 300 Oe. After the staged heat treatment was completed, a low-intensity alternating magnetic field of 50 Oe was applied as the temperature gradually decreased to 180℃. The application of the alternating magnetic field was divided into several cycles, with each cycle separated by 7 min, and the duration of each stage of the alternating magnetic field was 20 min.

[0083] S303, cutting and grinding the soft magnetic alloy bulk cooled after the hierarchical heat treatment (using cooling liquid to prevent overheating), ensuring the size and surface finish; adopting multi-pass cold rolling to roll into strip, the thickness reduction of each pass of the multi-pass cold rolling being 7%, and then annealing at 400℃ to obtain the iron-based amorphous composite soft magnetic alloy.

[0084] Example 2 The present embodiment provides an iron-based amorphous composite soft magnetic alloy, the chemical components and atomic proportions of which are shown in Table 1.

[0085] The preparation method of the above-mentioned iron-based amorphous composite soft magnetic alloy comprises the following steps: S100, weighing each alloy raw material according to the atomic percentage, the purity of each alloy raw material being ≥99%, putting the alloy raw materials except rare earth elements and ceramic nano-particles into a vacuum induction melting furnace, the mass ratio of the alloy raw materials and the ceramic nano-particles being 100:0.1, melting at 1400℃, 8.5x10 -3 Pa under a protective atmosphere for 30min, cooling to room temperature, crushing and washing to obtain a mother alloy ingot.

[0086] S201, putting the mother alloy ingot into a vacuum induction melting furnace under a protective atmosphere, and melting at 1400℃, 8.5x10 -3 Pa for the second time, continuing to melt for 10min under the action of electromagnetic stirring after the mother alloy ingot is completely melted; then adding alloy raw materials containing rare earth elements into the molten alloy, immersing an ultrasonic transducer into the molten alloy, and ultrasonic treating at above the liquidus temperature of the metal, 25kHz, 200W / cm 2 for 20min, and spray cooling (spraying the molten alloy through a high-pressure nozzle to form fine droplets, and the cooling rate being 1.5x10 3 ℃ / s) to obtain micron-sized soft magnetic alloy particles.

[0087] S202, putting the soft magnetic alloy particles into a vacuum cavity of a plasma treatment device, vacuumizing to 8.5x10 -3 Pa, then introducing argon, opening a high-frequency power supply to excite the argon in the vacuum cavity to form plasma, treating the plasma for 10min, then closing the plasma source, slowly filling nitrogen into the vacuum cavity, gradually recovering the gas pressure, taking out the soft magnetic alloy particles treated by plasma, and drying at 60℃.

[0088] S301, putting the dried soft magnetic alloy particles into a mold under a protective atmosphere, pressing at 700℃, 700MPa for 60min, slowly reducing the pressure and naturally cooling to room temperature to obtain a soft magnetic alloy bulk.

[0089] S302, under a protective atmosphere, the soft magnetic alloy bulk is sequentially subjected to graded heat treatment at 320℃, 370℃ and 470℃, and each stage of treatment lasts for 1.2h; at the same time, an alternating magnetic field consistent with the main magnetization direction of the soft magnetic alloy particles is applied.

[0090] When the temperature rises to 180℃, an alternating magnetic field with a low intensity of 80Oe is first applied; when the heat treatment temperature reaches the target value (320℃-470℃) and remains for 1h, the intensity of the alternating magnetic field is gradually increased to 200Oe; after the end of the graded heat treatment, as the temperature gradually decreases to 180℃, an alternating magnetic field with a low intensity of 70Oe is applied. The application of the alternating magnetic field is divided into several cycles, each cycle is separated by 6min, and the duration of each stage of the alternating magnetic field is 15min.

[0091] S303, the soft magnetic alloy bulk after the graded heat treatment is cooled is cut and ground (using a cooling liquid to prevent overheating) to ensure the size and surface finish; a multi-pass cold rolling method is used to roll into a strip, and the thickness reduction of each pass of the multi-pass cold rolling is 8%, and then annealing at 500℃ is performed to obtain an iron-based amorphous composite soft magnetic alloy.

[0092] Example 3 The present embodiment provides an iron-based amorphous composite soft magnetic alloy, and the chemical components and atomic ratios thereof are shown in Table 1.

[0093] The preparation method of the above-mentioned iron-based amorphous composite soft magnetic alloy comprises the following steps: S100, according to the atomic percentage design, each alloy raw material is weighed, the purity of each alloy raw material is ≥99%, the alloy raw materials except rare earth elements and ceramic nano-particles are put into a vacuum induction melting furnace, the mass ratio of the alloy raw materials and the ceramic nano-particles is 100:0.05, and the alloy raw materials and the ceramic nano-particles are melted at 1600℃, 8.4×10 -3 Pa under a protective atmosphere for 10min, and then cooled to room temperature, broken and washed to obtain a mother alloy ingot.

[0094] S201, under a protective atmosphere, the mother alloy ingot is put into a vacuum induction melting furnace, and is subjected to secondary melting at 1600℃, 8.4×10 -3 Pa, and after the mother alloy ingot is completely melted, the melting is continued for 7min under the action of electromagnetic stirring; then, alloy raw materials containing rare earth elements are added into the molten alloy, an ultrasonic transducer is immersed into the molten alloy, and the molten alloy is subjected to ultrasonic treatment at above the liquidus temperature of the metal, 40kHz and 800W / cm 2 for 10min, and then is subjected to spray cooling (the molten alloy is sprayed out through a high-pressure nozzle to form fine droplets, and the cooling rate is 1.2×10 3 ℃ / s) to obtain micron-sized soft magnetic alloy particles.

[0095] S202, put the soft magnetic alloy particles into the vacuum cavity of the plasma processing device, vacuumize to 8.4x10 -3 After 10 min, the plasma source is turned off, nitrogen is slowly filled into the vacuum cavity, and the gas pressure is gradually restored. The soft magnetic alloy particles after plasma treatment are taken out and dried at 50℃.

[0096] S301, under a protective atmosphere, the dried soft magnetic alloy particles are loaded into a mold, and after being pressed at 800℃ and a pressure of 600MPa for 100min, the pressure is slowly reduced and naturally cooled to room temperature to obtain a soft magnetic alloy block.

[0097] S302, under a protective atmosphere, the soft magnetic alloy block is sequentially subjected to staged heat treatment at 350℃, 430℃ and 500℃, with each stage being treated for 1h; at the same time, an alternating magnetic field consistent with the main magnetization direction of the soft magnetic alloy particles is applied.

[0098] When the temperature rises to 150℃, a low-intensity alternating magnetic field of 30Oe is first applied; when the heat treatment temperature reaches the target value (350℃-500℃) and is maintained for 1h, the alternating magnetic field intensity is gradually increased to 500Oe; after the staged heat treatment is completed, a low-intensity alternating magnetic field of 30Oe is applied as the temperature gradually decreases to 150℃. The application of the alternating magnetic field is divided into several cycles, each cycle is separated by 5min, and the duration of each stage of the alternating magnetic field is 30min.

[0099] S303, the soft magnetic alloy block after staged heat treatment is cooled is cut and ground (using a cooling liquid to prevent overheating) to ensure the size and surface finish; a multi-pass cold rolling method is used to roll it into a strip, with each pass of the multi-pass cold rolling reducing the thickness by 5%, and then annealing at 300℃ to obtain an iron-based amorphous composite soft magnetic alloy.

[0100] Example 4 The present embodiment provides an iron-based amorphous composite soft magnetic alloy, the chemical composition and atomic ratio of which are shown in Table 1.

[0101] The preparation method of the above-mentioned iron-based amorphous composite soft magnetic alloy comprises the following steps: S100, according to the atomic percentage design, each alloy raw material is weighed, the purity of each alloy raw material is ≥99%, the alloy raw materials except rare earth elements and ceramic nanoparticles are placed in a vacuum induction melting furnace, the mass ratio of the alloy raw materials and the ceramic nanoparticles is 100:0.08, and the alloy raw materials and the ceramic nanoparticles are melted at 1550℃ and 9x10 -3 Pa for 20min under a protective atmosphere, cooled to room temperature, broken and washed to obtain a master alloy ingot.

[0102] S201, under a protective atmosphere, the master alloy ingot is put into a vacuum induction melting furnace, and is subjected to secondary melting at 1500℃, 8.9x10 -3 Pa, and after the master alloy ingot is completely melted, the melting is continued for 9 min under the action of electromagnetic stirring; then, alloy raw materials containing rare earth elements are added into the molten alloy, an ultrasonic transducer is immersed into the molten alloy, and the molten alloy is subjected to ultrasonic treatment at above the liquidus temperature of the metal, 15 kHz, 400 W / cm 2 After the ultrasonic treatment for 25 min, the molten alloy is subjected to spray cooling (the molten alloy is sprayed through a high-pressure nozzle to form fine droplets, and the cooling rate is 1.6x10 3 ℃ / s), and micron-sized soft magnetic alloy particles are obtained.

[0103] S202, the soft magnetic alloy particles are put into a vacuum cavity of a plasma treatment device, vacuum is drawn to 8.9x10 -3 Pa, argon is introduced, a high-frequency power supply is turned on to excite the argon in the vacuum cavity to form a plasma, the plasma is treated for 10 min, the plasma source is turned off, nitrogen is slowly filled into the vacuum cavity, and the gas pressure is gradually restored. The soft magnetic alloy particles after the plasma treatment are taken out and dried at 40℃.

[0104] S301, under a protective atmosphere, the dried soft magnetic alloy particles are loaded into a mold, and are pressed at 500℃ and a pressure of 900 MPa for 40 min, the pressure is slowly reduced and naturally cooled to room temperature, and a soft magnetic alloy block is obtained.

[0105] S302, under a protective atmosphere, the soft magnetic alloy block is sequentially subjected to staged heat treatment at 300℃, 390℃ and 460℃, and each stage of heat treatment lasts for 1.5 h; at the same time, an alternating magnetic field consistent with the main magnetization direction of the soft magnetic alloy particles is applied.

[0106] When the temperature rises to 200℃, an alternating magnetic field with a low intensity of 100 Oe is first applied; when the heat treatment temperature reaches the target value (300℃-460℃) and is maintained for 1 h, the intensity of the alternating magnetic field is gradually increased to 150 Oe; after the staged heat treatment is completed, an alternating magnetic field with a low intensity of 100 Oe is applied as the temperature gradually decreases to 200℃. The application of the alternating magnetic field is divided into several cycles, each cycle is separated by 10 min, and the duration of the alternating magnetic field in each stage is 10 min.

[0107] S303, the soft magnetic alloy block after the staged heat treatment is cooled is cut and ground (a cooling liquid is used to prevent overheating), and the size and surface finish are ensured; the soft magnetic alloy block is rolled into a strip by a multi-pass cold rolling method, the thickness reduction of each pass of the multi-pass cold rolling is 10%, and then the soft magnetic alloy block is annealed at 400℃, and an iron-based amorphous composite soft magnetic alloy is obtained.

[0108] Examples 5-12 Embodiments 5-12 each provide an iron-based amorphous composite soft magnetic alloy, the chemical composition and atomic ratio of which are shown in Table 1.

[0109] The preparation method of the iron-based amorphous composite soft magnetic alloy in embodiments 5-12 is the same as that in embodiment 1, and will not be repeated here.

[0110] Comparative examples 1-3 Comparative examples 1-3 each provide a commercially available iron-based amorphous composite soft magnetic alloy, the chemical composition and atomic ratio of which are shown in Table 1.

[0111] Table 1 Chemical composition and atomic ratio of the alloys in the embodiments and comparative examples

[0112] Verification test The iron-based amorphous composite soft magnetic alloys provided in embodiments 1-12 and comparative examples 1-3 were subjected to magnetic performance tests, and the test results are shown in Table 2 and Figs. 1-4 .

[0113] Among them, the test method is: Coercivity (Hc): closed loop Hall effect measurement method was used.

[0114] Saturation magnetic induction (Bs): tested using a vibrating sample magnetometer (VSM).

[0115] Magnetic loss (P): evaluated by a power loss measurement instrument at a low frequency of 50 Hz and an alternating magnetic field magnetic flux density of 1.0 T, and at a high frequency of 100 Hz and an alternating magnetic field magnetic flux density of 1.5 T.

[0116] Test environment: room temperature (about 25°C), humidity controlled at 50%.

[0117] Table 2 Magnetic performance test results of the alloys in the embodiments and comparative examples

[0118] As can be seen from Table 2 and Figs. 1-4 , compared with comparative examples 1-3, the iron-based amorphous composite soft magnetic alloys provided in embodiments 1-12 have obvious advantages in coercivity, saturation magnetic induction and magnetic loss and other magnetic properties.

[0119] (1) The coercivity of the alloys in embodiments 1-12 is 4.1 A / m-4.6 A / m, which is higher than that of comparative examples 1-3 (3.8 A / m-4.0 A / m), which can be considered as a significant advantage of the alloys in terms of resistance to magnetic field interference. High coercivity means that the alloy can maintain relatively stable magnetic properties during application, which is beneficial to improving the reliability and service life of the equipment. This also suggests that we need to find a balance between high magnetic stability and low loss.

[0120] (2) The saturation magnetic induction of the alloys in Examples 1-12 is 1.73T-1.86T, far exceeding that of Comparative Examples 1-3 (1.35T-1.4T). High saturation magnetic induction means that the alloy can still maintain good magnetic properties in a high magnetic field environment, which is particularly important for electric motors and transformers in high load working conditions. The iron-based amorphous composite soft magnetic alloy provided by the present application can effectively prevent the occurrence of saturation while meeting the high performance requirements.

[0121] (3) The low-frequency magnetic loss (50Hz, 1.0T) of the alloys in Examples 1-12 is 0.018W / kg-0.023W / kg, generally lower than that of Comparative Examples 1-3 (0.028W / kg-0.03W / kg). This indicates that the iron-based amorphous composite soft magnetic alloy provided by the present application has better energy efficiency in low-frequency applications and is suitable for electrical equipment such as electric motors and transformers.

[0122] (4) Under high-frequency (100kHz, 1.5T) conditions, the magnetic loss of the alloys in Examples 1-12 increases significantly, ranging from 18W / kg to 24W / kg, but is still better than that of Comparative Examples 1-3 (28W / kg-30W / kg). Compared with low-frequency magnetic loss, eddy current loss under high frequency has a greater impact on magnetic loss. By optimizing the alloy composition and structure, the present application successfully reduces the loss under high frequency, which makes the iron-based amorphous composite soft magnetic alloy provided by the present application have higher energy efficiency in high-frequency applications such as switching power supplies and high-frequency transformers.

[0123] The iron-based amorphous composite soft magnetic alloys provided by Examples 1-12 and Comparative Examples 1-3 were subjected to physical and mechanical performance tests, and the test results are shown in Table 3.

[0124] Table 3 Physical and mechanical performance test results of the alloys of Examples and Comparative Examples

[0125] As can be seen from Table 3, the iron-based amorphous composite soft magnetic alloy provided by Examples 1-12 of the present application has excellent mechanical properties compared to Comparative Examples 1-3.

[0126] (1) Hardness: The hardness of the alloys in Examples 1-12 is 605HV-640HV, while the hardness of the alloys in Comparative Examples 1-3 is 570HV-580HV, indicating that the iron-based amorphous composite soft magnetic alloy provided by the present application is superior to existing products in terms of wear resistance and deformation resistance, and is suitable for high stress and high wear environments.

[0127] (2) Tensile strength and yield strength: The tensile strength of the alloys in Examples 1-12 is 760MPa-820MPa, and the yield strength is 530MPa-580MPa, which is superior to that of Comparative Examples 1-3 (tensile strength 700MPa-710MPa, yield strength 500MPa-510MPa). This indicates that the iron-based amorphous composite soft magnetic alloy provided by the present invention has better strength and durability under tensile and load conditions.

[0128] (3) Ductility: The ductility of the alloys in Examples 1-12 is 6%-8.5%, while that of Comparative Examples 1-3 is higher (11.5%-12%). This means that the alloys in the comparative examples have better plastic deformation ability and are suitable for applications requiring more ductility. However, the ductility of the alloys in the embodiments of the present invention is sufficient to meet the application requirements of most soft magnetic alloys, and their strength is higher.

[0129] (4) Compressive strength: The compressive strength of the alloys in Examples 1 to 12 is 1165 MPa to 1240 MPa, which is significantly higher than that of Comparative Examples 1 to 3 (1085 MPa to 1100 MPa), indicating that the iron-based amorphous composite soft magnetic alloy provided by the present invention has stronger performance in terms of compressive strength and deformation resistance.

[0130] (5) Density: The density of the alloys in Examples 1-12 is 7.58 g / cm³. 3 ~7.72g / cm 3 Slightly higher than comparative examples 1-3 (7.48 g / cm³). 3 ~7.50g / cm 3 Higher density usually means a more compact microstructure in the alloy, which helps to improve magnetic properties.

[0131] (6) Elastic modulus: The elastic modulus of the alloys in Examples 1-12 is 191 GPa to 210 GPa, while the elastic modulus of the alloys in Comparative Examples 1-3 is 180 GPa to 185 GPa. The higher the elastic modulus, the greater the rigidity of the alloy and the stronger its resistance to deformation. The alloys in the embodiments of the present invention perform well in resisting elastic deformation and are suitable for high-stress applications.

[0132] (7) Fracture toughness: The fracture toughness of the alloys in Examples 1-12 is 22 MPa·m. 1 / 2 ~28MPa·m 1 / 2 Higher than comparative examples 1-3 (19 MPa·m 1 / 2 ~20MPa·m 1 / 2 This indicates that the iron-based amorphous composite soft magnetic alloy provided by the present invention is less prone to cracking or fracture under high stress and has better fatigue resistance.

[0133] (8) Resistivity: The resistivity of the alloys in Examples 1-12 ranged from 126 to 136 µΩ-cm, while the resistivity of the alloys in Comparative Examples 1-3 was 150 to 155 µΩ-cm. Lower resistivity means better electrical conductivity of the alloy, which reduces eddy current losses, especially in high frequency applications.

[0134] In summary, the iron-based amorphous composite soft magnetic alloy of the present application is significantly superior to the mainstream products in performance. The combination of high mechanical strength, high magnetic permeability and saturation magnetic induction provides a good material basis for high-efficiency electrical equipment; moderate coercive force enhances the reliability of the material under complex working conditions; and low magnetic loss not only reduces the operating cost, but also improves the overall performance of the equipment.

[0135] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A type of iron-based amorphous composite soft magnetic alloy, characterized in that, Its chemical formula is Fe a Co b Ni c X d B e P f Si g Y h X represents a transition metal element, Y represents a rare earth element, and a, b, c, d, e, f, g, and h represent the atomic percentage content of the corresponding chemical components. Among them, 55≤a≤60.1, 15≤b≤20, 8≤c≤12, 6≤d≤9, 0.2≤e≤0.7, 0.01≤f≤0.03, 2≤g≤4, 2≤h≤4, a+b+c+d+e+f+g+h=100, 58≤a+0.4b-0.2c≤67, 4.5≤2.5e+g+0.6h≤7.

5.

2. The iron-based amorphous composite soft magnetic alloy as described in claim 1, characterized in that, X is selected from at least two of Cr, Mn, Mo, Ti or V; The Y is selected from at least two of La, Nd, or Sm.

3. The iron-based amorphous composite soft magnetic alloy as described in claim 2, characterized in that, The atomic percentage of Cr is 1%~4%, the atomic percentage of Mn is 1%~3%, the atomic percentage of Mo is 1%~6%, the atomic percentage of Ti is 1%~3%, and the atomic percentage of V is 0.1%~3%. The atomic percentage of La is 1% to 2%, the atomic percentage of Nd is 1% to 2%, and the atomic percentage of Sm is 1% to 2%.

4. The method for preparing the iron-based amorphous composite soft magnetic alloy according to any one of claims 1 to 3, characterized in that, Includes the following steps: S100. Weigh each alloy raw material according to the atomic percentage design, put the alloy raw materials except rare earth elements and ceramic nanoparticles into a vacuum induction melting furnace, and melt them under a protective atmosphere to obtain the master alloy ingot. S200. Under a protective atmosphere, the master alloy ingot is smelted a second time, and then alloy raw materials containing rare earth elements are added to the molten alloy. Spray cooling is performed to obtain soft magnetic alloy particles. S300. Under a protective atmosphere, the soft magnetic alloy particles are pressed at 500℃~800℃, and then subjected to graded heat treatment at 300℃~350℃, 370℃~430℃ and 450℃~500℃ in sequence, while an alternating magnetic field is applied; then rolled into shape to obtain an iron-based amorphous composite soft magnetic alloy.

5. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S100, the mass ratio of the alloy raw material to the ceramic nanoparticles is 100:(0.05~0.1).

6. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S100, the melting temperature is 1400℃~1600℃, and the absolute pressure is ≤9×10⁻⁶. -3 Pa, melting time is 10min~30min; In S200, the temperature of the secondary melting is 1400℃~1600℃, and the absolute pressure is ≤9×10⁻⁶. -3 Pa, the secondary melting time is 7 min to 10 min.

7. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S200, the cooling rate of the spray cooling is ≥10. 3 The temperature is ℃ / s, and the particle size of the soft magnetic alloy particles is in the micrometer range.

8. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S200, after the spray cooling is completed, the following is also included: The soft magnetic alloy particles were placed under an absolute pressure ≤9×10 -3 In Pa's plasma treatment equipment, a rare gas is introduced, the power is turned on to perform plasma treatment, and then the plasma is dried.

9. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S300, the pressing temperature is 600℃~700℃, the pressure is 500MPa~1000MPa, and the heat and pressure holding time is 30min~120min; In S300, the processing time for each stage of the graded heat treatment is 1h to 1.5h.

10. The method for preparing the iron-based amorphous composite soft magnetic alloy as described in claim 4, characterized in that, In S300, the strength of the alternating magnetic field is 10Oe~1000Oe, and the frequency is 1Hz~100Hz.

Images