High-permeability nanocrystalline soft magnetic alloy, strip and preparation method and application of high-permeability nanocrystalline soft magnetic alloy

Abstract

The invention relates to a nanocrystalline soft magnetic alloy with high magnetic conductivity, a strip and a preparation method and application of the nanocrystalline soft magnetic alloy. The chemical formula of the nanocrystalline soft magnetic alloy with the high magnetic conductivity is FeaCobNicTidSihBfRjMk (NbO) x, wherein R is a rare earth element and is selected from at least one of La, Nd and Y; m is a transition metal element and is selected from at least one of Zr and Hf; a, b, c, d, h, f, j and k are atomic percentages of the corresponding components: 72 < = a < = 85, 2 < = b < = 5, 3 < = c < = 8, 1 < = d < = 2, 2 < = h < = 4, 2 < = f < = 4, 0.5 < = j < = 1, 0.5 < = k < = 2, 0.5 < = x < = 2, and the sum of the atomic percentages of all the components is 100. The nanocrystalline soft magnetic alloy disclosed by the invention has high magnetic conductivity, low loss and excellent mechanical property and thermal stability.

Description

Technical Field

[0001] The present invention belongs to the field of soft magnetic alloys and their preparation, and particularly relates to a high magnetic permeability nanocrystalline soft magnetic alloy, strip, and their preparation methods and applications. Background Art

[0002] Soft magnetic materials are a type of materials that can be easily magnetized and demagnetized under an external magnetic field, with characteristics such as high magnetic permeability, low coercivity, and low loss, and are one of the key materials in modern power electronic devices. Common soft magnetic materials include silicon steel, ferrite, and amorphous alloys. However, in high-frequency electromagnetic applications, these traditional materials face certain performance bottlenecks and are difficult to meet the requirements of new-generation power equipment for high efficiency, low loss, and high-frequency stability.

[0003] As a traditional soft magnetic material, it has certain limitations. For example, silicon steel, as a widely used soft magnetic material, has good low-frequency magnetic properties and high mechanical strength. However, silicon steel exhibits large eddy current losses and low magnetic permeability under high-frequency conditions and is difficult to be effectively applied in high-frequency transformers and high-frequency motors.

[0004] For ferrite, it has a high resistivity and low eddy current losses, but its saturation magnetic induction intensity is low, it cannot withstand a high magnetic flux density, and at the same time its brittleness is large, making it difficult to meet the requirements of some high-strength mechanical applications.

[0005] For amorphous alloys, due to their amorphous structure, they have low loss and high magnetic permeability and are excellent in high-frequency applications. However, amorphous alloys have poor thermal stability at high temperatures and lack sufficient mechanical strength, making it difficult to be widely applied in some high-strength scenarios.

[0006] In contrast, nanocrystalline soft magnetic alloys have application advantages in the above aspects. First, nanocrystalline soft magnetic alloys are composite structural materials formed by controlling the grain size at the nanometer level on the basis of amorphous alloys. While maintaining low loss and high magnetic permeability, they have better mechanical properties and thermal stability and are an ideal high-frequency soft magnetic material. Second, existing nanocrystalline soft magnetic alloys mostly adopt combinations of elements such as iron, silicon, and boron, and the magnetic properties can be further improved by adding cobalt, nickel, and rare earth elements. Although there have been some studies and applications, there is still much room for improvement in how to effectively refine grains, improve thermal stability, and reduce losses.

[0007] While traditional nanocrystalline soft magnetic alloys achieve high magnetic permeability and low loss, it is often difficult to balance thermal stability, and grain growth is likely to occur in a high-temperature environment, resulting in performance degradation. And for high-frequency applications, the control of eddy current loss and hysteresis loss is crucial. However, in existing nanocrystalline soft magnetic alloys, the uniformity and nanocrystallization degree of grains have not reached an ideal state, resulting in large losses of the material under high-frequency conditions.

[0008] Regarding the high magnetic flux density requirements in complex power electronic devices, the current nanocrystalline alloys still have deficiencies in saturation magnetic induction intensity and cannot maintain good magnetic properties under high load conditions. In addition, existing preparation methods often face challenges in stability and consistency in industrial production, making it difficult to ensure high-performance output in mass production. Summary of the Invention

[0009] The object of the present invention is to solve the problems of high loss, poor thermal stability, and low saturation magnetic induction intensity of existing nanocrystalline soft magnetic materials at high frequencies.

[0010] The object of the present invention is achieved by the following technical solutions: A high magnetic permeability nanocrystalline soft magnetic alloy, and the chemical formula of the high magnetic permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ; wherein, R is a rare earth element selected from at least one of La, Nd, and Y; M is a transition metal element selected from at least one of Zr and Hf; a, b, c, d, h, f, j, k are the atomic percentages of the corresponding components respectively: 72 ≤ a ≤ 85, 2 ≤ b ≤ 5, 3 ≤ c ≤ 8, 1 ≤ d ≤ 2, 2 ≤ h ≤ 4, 2 ≤ f ≤ 4, 0.5 ≤ j ≤ 1, 0.5 ≤ k ≤ 2, 0.5 ≤ x ≤ 2, and the sum of the atomic percentages of all components is 100.

[0011] Preferably, the NbO is niobium oxide, which is introduced as a reactive substance during melting and reacts with boron and silicon to form a composite phase.

[0012] In the initial stage of melting, different from the previous alloys using elemental niobium as raw material, niobium oxide is introduced as a reactive substance during melting. First, it reacts with boron to form niobium boride (NbB2), releasing heat and promoting the stability of the reaction environment. Then, niobium continues to react with silicon to form niobium silicide (NbSi2). This process can effectively refine the grain structure, enhance the uniformity between grains, and improve the magnetic permeability of the iron-based alloy under the action of niobium element, while maintaining the low coercivity and high magnetic saturation intensity of the alloy.

[0013] The niobium silicide and niobium boride formed by the composite reaction of niobium oxide with boron and silicon effectively reduce the hysteresis loss and eddy current loss. The composite phase of niobium silicide and niobium boride effectively inhibits grain growth through the "pinning effect", ensuring that the grains are within the nanoscale range; and this refinement effect not only improves the soft magnetic properties but also enhances the mechanical strength and thermal stability of the alloy. At the same time, the high melting point characteristics of niobium silicide and niobium boride endow the alloy with thermal stability in high-temperature environments. This means that during high-temperature annealing or actual application, the microstructure of the alloy can remain stable, preventing abnormal grain growth, thereby ensuring the long-term stability of the soft magnetic properties in high-temperature environments.

[0014] Preferably, the high-permeability nanocrystalline soft magnetic alloy is a high-permeability nanocrystalline soft magnetic alloy strip.

[0015] Preferably, the resistivity of the soft magnetic alloy strip is 150 - 180 μΩ•cm; and / or the saturation magnetic induction intensity of the soft magnetic alloy strip is 1.7 - 2.1 T; and / or the high-frequency loss of the soft magnetic alloy strip at a frequency of 10 kHz and a magnetic flux density of 1 T is 10 - 20 W / kg.

[0016] The present invention also provides a method for preparing the high-permeability nanocrystalline soft magnetic alloy strip, comprising the following steps: Precisely weigh the raw materials of iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, NbO and transition metals according to the alloy composition of the high-permeability nanocrystalline soft magnetic alloy, and the purity of all raw materials needs to be greater than 99%; After mixing the raw materials, heat them to 1800 - 2000 °C under the protection of inert gas and melt for 5 - 10 minutes to obtain a molten alloy; Cool the molten alloy by centrifugal casting process to obtain alloy sheets; Clean and dry the alloy sheets, and ball-mill the dried alloy sheets to obtain refined particles; Put the refined particles into a mold and perform hot pressing at a temperature of 600 - 900 °C, with a forming pressure of 400 - 800 MPa and a forming time of 30 - 60 minutes to obtain a bulk material; Place the bulk material in a hot rolling mill and perform multi-pass rolling at a temperature of 500 - 700 °C to obtain a strip with a thickness of 10 - 14 μm; Continuous annealing: Perform continuous annealing treatment on the strip at 250 - 560 °C for 2 - 4 hours to obtain the high-permeability nanocrystalline soft magnetic alloy strip.

[0017] Preferably, the inert gas is argon with a purity greater than 99.99%. In plasma melting, the use of high-purity argon can prevent impurities from contaminating the molten metal. By strictly controlling the melting temperature and time, element loss and incomplete reactions can be prevented.

[0018] Preferably, the rapid cooling of the molten alloy by centrifugal casting specifically includes: Rapidly cooling the molten alloy by centrifugal casting under vacuum conditions, with a cooling rate greater than 10 4 K / s.

[0019] The rapid centrifugal cooling process is carried out under vacuum conditions, which can avoid oxidation on the alloy surface and ensure the stability of the centrifugal speed and cooling rate; the cooling rate must be controlled to be greater than 10 4 K / s to ensure that the alloy rapidly solidifies to form flaky materials and achieves a preliminary transition to amorphous and nanocrystalline structures at the microstructural level.

[0020] Preferably, the drying specifically includes: performing in a vacuum drying oven at a drying temperature of 50 - 100 °C.

[0021] Preferably, in the ball milling treatment, the ball milling medium is cemented carbide balls and the ball milling time is 1 - 2 hours.

[0022] Using cemented carbide balls as the ball milling medium can reduce the contamination of the material during the ball milling process.

[0023] Preferably, in the hot pressing forming treatment, the forming pressure is 600 - 800 MPa and the forming time is 45 - 60 minutes.

[0024] Preferably, the number of rolling passes is not less than 5.

[0025] Preferably, the continuous annealing treatment adopts a step annealing process, with the first-stage temperature being 200 - 300 °C; the second-stage temperature being 300 - 400 °C; the third-stage temperature being 400 - 500 °C; the fourth-stage temperature being 520 - 560 °C; the treatment time for each stage does not exceed 1 hour, and the total continuous annealing time does not exceed 4 hours.

[0026] During the continuous annealing process, temperature control is crucial, and the step treatment can effectively promote the stabilization of the nanocrystalline structure and improve the magnetic properties. Additionally, the annealing process helps with the homogenization of the nanocrystalline phase, improving the magnetic permeability and soft magnetic properties. The treatment time for each stage does not exceed 1 hour, and the total continuous annealing time does not exceed 4 hours. Within this time range, grain growth can be prevented.

[0027] Preferably, it further includes surface treatment of the high magnetic permeability nanocrystalline soft magnetic alloy strip using electrolytic polishing technology.

[0028] The present invention also provides the application of the high magnetic permeability nanocrystalline soft magnetic alloy strip prepared by the described preparation method in high-frequency transformers, inductors, and stators and rotors of electric motors.

[0029] In practical applications, the high magnetic permeability nanocrystalline soft magnetic alloy strip can also be cut and formed into a coil according to application requirements.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The high magnetic permeability nanocrystalline soft magnetic alloy provided by the present invention, the chemical formula of the high magnetic permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ; wherein, R is a rare earth element selected from at least one of La, Nd, and Y; M is a transition metal element selected from at least one of Zr and Hf; the a, b, c, d, h, f, j, k are the atomic percentages of the corresponding components: 72 ≤ a ≤ 85, 2 ≤ b ≤ 5, 3 ≤ c ≤ 8, 1 ≤ d ≤ 2, 2 ≤ h ≤ 4, 2 ≤ f ≤ 4, 0.5 ≤ j ≤ 1, 0.5 ≤ k ≤ 2, 0.5 ≤ x ≤ 2, and the sum of the atomic percentages of all components is 100. Through the combined action of reasonably proportioned iron, cobalt, nickel, silicon, and rare earth elements, the present invention realizes the optimization of the magnetic domain structure and the reduction of magnetic loss, and the magnetic permeability of the alloy is significantly improved. Especially in high-frequency applications, the magnetic response ability can be significantly enhanced; the addition of transition metals (such as zirconium and hafnium) enables the alloy to exhibit better structural stability at high temperatures. These elements form a variety of nano-scale composite phases through complex reactions with titanium, boron, and rare earth elements, significantly improving the oxidation resistance and magnetic properties of the alloy under high-temperature conditions. The present invention adopts the synergistic action of multiple elements, including iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, niobium oxides, and transition metals. This diversified design enables the material to not only have high magnetic permeability and low loss but also be optimized in mechanical properties and thermal stability, especially having high tensile strength and ductility. In summary, the nanocrystalline soft magnetic alloy in the present invention has significant electromagnetic properties, excellent mechanical properties and thermal stability, and at the same time has good process stability and cost-effectiveness, making the alloy perform excellently in high-frequency electromagnetic application scenarios and having broad application potential and market value.

[0031] The preparation method of the high magnetic permeability nanocrystalline soft magnetic alloy provided by this application forms a strip with a uniform nanocrystalline structure through processes such as plasma melting, rapid cooling, ball milling, hot pressing, hot rolling, and continuous annealing. Rapid cooling and a reasonable annealing process promote the formation and stabilization of the nanocrystalline phase, effectively improving the comprehensive properties of the alloy. Moreover, this preparation method has stable processes and is suitable for mass production, ensuring the consistency and quality stability of the products.

[0032] The high magnetic permeability nanocrystalline soft magnetic alloy provided by the present invention is applicable to the stators and rotors of high-frequency transformers, inductors, and electric motors. Due to its high magnetic permeability, low loss, and high thermal stability, it can significantly improve the efficiency and stability of these devices under high-frequency working conditions. Detailed implementation manners

[0033] The technical solutions of the present invention are clearly and completely described below through examples. Obviously, the described examples are only a part of the examples of the present invention, and cannot be regarded as all the examples. All other examples obtained by those of ordinary skill in the art based on the examples of the present invention without creative efforts fall within the scope of protection of the present invention.

[0034] A high magnetic permeability nanocrystalline soft magnetic alloy, the chemical formula of the high magnetic permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ; wherein, R is a rare earth element, selected from at least one of La, Nd, and Y; M is a transition metal element, selected from at least one of Zr and Hf; The a, b, c, d, h, f, j, k are the atomic percentages of the corresponding components: 72 ≤ a ≤ 85, 2 ≤ b ≤ 5, 3 ≤ c ≤ 8, 1 ≤ d ≤ 2, 2 ≤ h ≤ 4, 2 ≤ f ≤ 4, 0.5 ≤ j ≤ 1, 0.5 ≤ k ≤ 2, 0.5 ≤ x ≤ 2, and the sum of the atomic percentages of all components is 100.

[0035] The NbO is niobium oxide, which is introduced as a reactive substance during the melting process and reacts with boron and silicon to form a composite phase.

[0036] In the present invention, except for NbO which is niobium oxide, the raw materials of the above chemical formula are all elemental substances of each element, and all are of high purity: greater than 99%.

[0037] The functions of each element in the alloy of the present invention are described as follows: Iron (Fe) is the main component of the iron-based nanocrystalline soft magnetic alloy, which provides high magnetic permeability and magnetic saturation intensity and is the core basis of soft magnetic properties. When the atomic percentage content of Fe is 72 ≤ a ≤ 85, as the matrix metal, the interaction between iron and other elements can form a stable grain structure of the alloy and the distribution of the nanocrystalline phase. At the same time, the formed amorphous / nanocrystalline composite structure ensures relatively high magnetic permeability and magnetic saturation intensity. When the atomic percentage of Fe is less than 72, the interaction between iron and other elements becomes weak, and the strength of the formed alloy is insufficient, thus affecting subsequent applications.

[0038] The function of cobalt (Co) is to increase the magnetic saturation intensity and magnetic permeability, and it performs better especially in high-frequency applications. In addition, the cobalt element can provide better thermal stability and reduce the performance degradation of the material at high temperatures. When the atomic percentage content of Co is 2 ≤ b ≤ 5, it is more likely to form a eutectic phase with iron, thereby improving the magnetic properties of the material. At the same time, it can promote the formation of nanocrystals during the melting process. And when the atomic percentage content of Co is within the above range, it is easy to form a complex phase with silicon, titanium, and rare earth elements, further refining the grain structure. However, when the atomic percentage of Co is greater than 5, it will cause an increase in magnetic loss and coercivity, and the soft magnetic properties will deteriorate.

[0039] The function of nickel (Ni) is to increase the corrosion resistance and workability of the alloy, and it also helps to improve the magnetic permeability; in a high-frequency magnetic field, nickel can reduce the hysteresis loss. When the atomic percentage content of Ni is 3 ≤ c ≤ 8, it is more likely to form a solid solution with iron and cobalt, which helps to stabilize the nanocrystalline phase. And when the atomic percentage content of Ni is within the above range, nickel further promotes the uniform distribution of boron during the melting process, which helps to form nanocrystals. However, when the atomic percentage of Ni is greater than 8, it will cause an increase in eddy current loss and coercivity, and the soft magnetic properties will deteriorate.

[0040] The function of titanium (Ti) is to act as a grain refiner. Titanium can inhibit the growth of grains and help to maintain the uniformity of the nanocrystalline structure. It enhances the mechanical properties of the alloy, making the strip have better tensile strength and wear resistance. When the atomic percentage content of Ti is 1 ≤ d ≤ 2, titanium is more likely to form titanium boride or titanium silicide with boron and silicon during the melting process, which helps to uniformly distribute the nanocrystalline phase and refine the grains; at the same time, within this range, by acting together with rare earth elements, it can improve the structural stability of the alloy, especially ensuring the structural stability of the alloy during high-temperature annealing. When the atomic percentage of Ni is greater than 2, it will cause a decrease in the saturation magnetic induction.

[0041] The role of silicon (Si) is to increase the resistivity of the alloy, which helps reduce eddy current losses; it promotes the formation of the amorphous phase and further improves the soft magnetic properties of the alloy. When the atomic percentage content of Si is 2 ≤ h ≤ 4, silicon is more likely to react with niobium oxides during melting to form niobium silicides, which helps refine the grain structure; at the same time, silicon dissolves with iron and nickel, which helps improve the distribution uniformity of the nanocrystalline phase and maintain structural stability during subsequent heat treatment. However, when the atomic percentage of Si is greater than 4, it will cause a decrease in saturation magnetic induction.

[0042] Boron (B) is a typical nanocrystal-forming element that promotes the rapid formation of the amorphous phase. It increases the high-frequency magnetic permeability of the alloy while reducing the hysteresis loss. When the atomic percentage content of B is 2 ≤ f ≤ 4, boron reacts with titanium, rare earth elements, and niobium oxides to form titanium borides and niobium borides, which further refine the grains and improve the high-temperature performance of the material; and during melting and annealing, the interaction between boron and rare earth elements can help reduce impurities and improve magnetic properties. When the atomic percentage of B is greater than 4, it will cause a decrease in saturation magnetic induction.

[0043] Rare earth elements (lanthanum La, neodymium Nd, yttrium Y) help improve the high magnetic permeability and antioxidant capacity of nanocrystalline soft magnetic alloys. In the alloy, the addition of rare earth elements can significantly reduce the impurity content and improve the magnetic properties of the alloy. When the atomic percentage content of rare earth elements is 0.5 ≤ j ≤ 1, rare earth elements react with titanium and boron during melting to form composite phases. These composite phases can further refine the grains, promote the stabilization of the amorphous and nanocrystalline phases, and inhibit grain growth during high-temperature annealing to maintain the uniformity of the nanocrystalline structure. When the atomic percentage of rare earth elements is greater than 1, it will cause a decrease in saturation magnetic induction and deterioration of magnetic properties.

[0044] Niobium oxides (NbO) are introduced as reactive substances, which react with boron and silicon during melting to form niobium silicides and niobium borides. When the atomic percentage content of niobium oxides is 0.5 ≤ x ≤ 2, these composite phases help improve the magnetic permeability, refine the grains, and improve the thermal stability of the material. And the chain reaction of niobium oxides with silicon and boron promotes the formation of complex nanocomposite phases, which can significantly improve the soft magnetic properties of the alloy; at the same time, if the atomic percentage content of niobium oxides is within this range, niobium oxides can also regulate the grain size and distribution of the alloy and enhance the high-temperature resistance of the material. When the atomic percentage of niobium oxides is greater than 2, it will cause a decrease in saturation magnetic induction and deterioration of magnetic properties. The atomic percentage content of niobium oxides is preferably 0.6 ≤ x ≤ 1.8, more preferably 0.75 ≤ x ≤ 1.5.

[0045] Regarding the mechanism of the improvement of material properties by the formation of composite phases of niobium oxides: The reaction of niobium oxides with silicon: During the smelting process, niobium oxides can chemically react with silicon to form niobium silicide (NbSi2). This compound belongs to high melting point and hard compounds and is distributed in the melt in the form of nanoparticles. In addition, the formation of niobium silicide helps to inhibit grain growth because it forms a hindrance effect at the grain boundaries, preventing the further expansion of grains. Moreover, the nanoscale niobium silicide particles can also promote the formation and stability of amorphous and nanocrystalline phases in the alloy matrix.

[0046] Reaction of niobium oxides with boron: Niobium oxides can also react with boron at high temperatures to form niobium borides (such as NbB2). Niobium borides are a kind of hard phase and can act as a strong and effective grain refiner, thereby further reducing the grain size and being uniformly distributed in the material matrix. In addition, the formation of niobium borides also helps to inhibit grain growth and can improve the magnetic permeability of the material. And the nanostructured composite phase can effectively optimize the magnetic domain structure and improve the soft magnetic properties of the material.

[0047] Function of grain refinement: The nanoscale distribution of the formed niobium silicide and niobium boride inhibits the grain growth in the iron-based alloy through the pinning effect of grain boundaries. This refinement effect not only improves the strength and hardness of the alloy, but also improves the soft magnetic properties. And the refinement and homogenization of grains can reduce the movement resistance of magnetic domain walls, improving the magnetic permeability and magnetic saturation intensity.

[0048] Function of improving magnetic permeability: The presence of niobium silicide and niobium boride improves the uniformity and consistency of magnetic domains inside the material. Since these nanoscale composite phases form a continuous distribution in the alloy matrix, they help to reduce the hysteresis loss, thereby improving the magnetic permeability. And these composite phases make the movement of magnetic domain walls easier by reducing the energy barrier at grain boundaries in the microstructure, significantly improving the magnetic properties of the alloy.

[0049] Function of enhancing thermal stability: The presence of niobium silicide and niobium boride increases the high-temperature stability of the alloy. Due to the high melting point and good thermal stability of these composite phases, they can effectively inhibit the abnormal growth of matrix grains in a high-temperature environment, thereby maintaining the stable microstructure of the alloy. This means that in high-temperature annealing or actual applications, the soft magnetic properties of the alloy can be maintained for a long time, avoiding performance degradation caused by grain growth.

[0050] In addition, in the nanocrystalline soft magnetic alloy of the present invention, transition metals (zirconium Zr, hafnium Hf) are used as additional grain refiners, which can further refine the grains of the alloy during the smelting process, improving its structural stability and magnetic permeability. The composite reactions with titanium, boron and rare earth elements form a variety of composite phases, and these composite phases can all help to maintain the nanocrystalline structure and stability of the material.

[0051] As described above, through the mutual reaction of the above elements and the formation of the composite phase, they can jointly refine the grains, enhance the magnetic permeability, reduce the loss, improve the high-temperature resistance and thermal stability. The comprehensive effects of these elements and their interactions ensure that the iron-based nanocrystalline soft magnetic alloy has high magnetic permeability, low loss, high magnetic saturation intensity and good thermal stability. By reasonably proportioning the elements and optimizing their interactions, a stable nanocrystalline phase can be formed in the microstructure, further improving the soft magnetic properties of the material.

[0052] Furthermore, the resistivity of the alloy is 150-180 μΩ•cm, the saturation magnetic induction intensity is 1.7-2.1 T, and the high-frequency loss is 10-20 W / kg at a frequency of 10 kHz and a magnetic flux density of 1 T.

[0053] The alloy of the present invention can be used for the stators and rotors of high-frequency transformers, inductors and motors.

[0054] Example 1 This example provides a nanocrystalline soft magnetic alloy, and the chemical formula of the nanocrystalline soft magnetic alloy is: Fe 76 Co5Ni7Ti1Si3B4R1M2(NbO)1; wherein, R is La; M is Zr; NbO is niobium oxide.

[0055] This example also provides a nanocrystalline soft magnetic alloy strip, and the preparation method of the strip includes the following steps: 1) Raw material preparation According to the above element chemical composition formula, weigh iron, cobalt, nickel, titanium, silicon, boron, La, niobium oxide and Zr with a purity greater than 99%; And accurately weigh according to the preset ratio of the above chemical formula; Ensure that all raw materials are evenly mixed and placed in a dry environment to prevent the influence of impurities and moisture.

[0056] 2) Plasma melting Put all the raw materials into a plasma melting furnace and heat them under an argon atmosphere (argon purity ≥ 99.99%); The melting temperature is set at 1850 °C and the melting time is 610 minutes to ensure that the alloy raw materials are completely melted and fully mixed.

[0057] 3) Rapid centrifugal cooling The molten alloy is thrown out through a centrifugal casting device at a rotational speed of 35 m / s, and then rapidly cooled at a rate greater than 10 4 K / s to form an alloy sheet.

[0058] 4) Cleaning and drying The alloy flakes formed by centrifugal casting are immersed in deionized water for cleaning. Subsequently, the flakes are placed in a vacuum drying oven for drying, and the drying temperature is controlled at 60 °C to remove surface moisture.

[0059] 5) Ball milling The dried alloy flakes are placed into a high-energy ball mill, and cemented carbide balls are used as the ball milling medium. The ball milling time is 1 hour to further refine the particles and improve the uniformity.

[0060] 6) Hot pressing The particles after the above ball milling are loaded into a mold and hot pressed at a temperature of 650 °C. The pressing force is set at 700 MPa and maintained for 50 minutes to ensure the tight combination and densification of the particles, forming a bulk material.

[0061] 7) Hot rolling The bulk material after hot pressing is placed in a hot rolling mill and rolled 6 times at a temperature of 600 °C to roll the bulk material into a strip with a thickness of 10 μm to achieve an ideal nanocrystalline structure.

[0062] 8) Continuous annealing The rolled strip is placed in a continuous annealing furnace and treated by a step annealing process to obtain an annealed strip. The step annealing temperatures at this time are 250 °C, 350 °C, 450 °C, and 550 °C respectively, and the treatment time for each step is 1 hour, and the total annealing time is 4 hours.

[0063] 9) Surface treatment and forming The above annealed strip is subjected to electrolytic polishing forming, thereby obtaining a nanocrystalline soft magnetic alloy strip.

[0064] Example 2 - 12 The alloy composition and percentage content of Examples 2 to 12 are shown in Table 1. The preparation method is basically the same as that of Example 1, and the specific process parameters are different as shown in Table 2.

[0065] Table 1 Composition of Examples 1 - 12

[0066] Table 2 Process conditions adopted in the preparation methods of Examples 1 - 12

[0067] Comparative Examples 1 - 3 Three comparative products on the market were used for relevant comparisons. The composition of the comparative products is shown in Table 3.

[0068] Table 3 Composition of Comparative Examples 1 - 3

[0069] Test Example Performance tests were conducted on the high magnetic permeability nanocrystalline soft magnetic alloy strips prepared in Examples 1-2, and relevant comparisons were made with three comparative products (Comparative Examples 1-2) on the market. The test results are shown in Table 4.

[0070] Table 4 Performance test results of Examples 1-12 and Comparative Examples 1-3

[0071] Methods and equipment used for testing the performance of the above products: 1. Resistivity test Test method: The four-probe method was used to measure the resistivity of the alloy strip.

[0072] Test conditions: Conducted at room temperature, and the sample size was 20 mm×5 mm ×0.013 mm.

[0073] Result analysis: As can be seen from Tables 1-4, in Examples 1-12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the resistivity range of the obtained nanocrystalline soft magnetic alloy strip is 160-172 μΩ•cm. Compared with the comparative examples where the content of each component and the process conditions are not within the scope of the present invention, it is higher than that of the existing Comparative Examples 1-3 (150-155 μΩ•cm). Therefore, the products of the present invention meet the target requirements of the market (160-180 μΩ•cm). Thus, it can be seen that the alloy strip of the present invention has a relatively high resistivity, which means that the strip has lower eddy current loss under high-frequency conditions.

[0074] 2. Saturation magnetic induction intensity test Test method: A vibrating sample magnetometer (VSM) was used to measure the saturation magnetic induction intensity under an applied magnetic field.

[0075] Test conditions: In the magnetic field range of 0-2 T, the sample size was 10 mm×10 mm ×0.013 mm.

[0076] Result analysis: As can be seen from Tables 1-4, in Examples 1-12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the saturation magnetic induction intensity of the obtained nanocrystalline soft magnetic alloy strip is between 1.7-1.85 T, which is significantly higher than that of the comparative examples with indicators not within the scope of the present invention, which is 1.52-1.6 T.

[0077] This shows that the nanocrystalline soft magnetic alloy of the present invention has higher magnetic saturation performance and is more suitable for high magnetic flux density application scenarios.

[0078] 3. Coercivity Test Test method: The B-H curve measurement method is adopted to evaluate the coercivity of the alloy.

[0079] Test conditions: Measure under the magnetic field conditions of 25 °C and 0 - 100 A / m.

[0080] Result analysis: As can be seen from Table 1 - 4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the coercivity of the obtained nanocrystalline soft magnetic alloy strip is between 2.1 - 3.0 A / m, much lower than 3.5 - 3.8 A / m of the comparative examples not within the scope of the present invention.

[0081] As known to those skilled in the art, the lower the coercivity, the better its magnetic properties. Therefore, materials with lower coercivity are more suitable for the application requirements of high-frequency transformers and inductors.

[0082] 4. High-frequency Loss Test Test method: Use an iron loss analyzer to conduct the test at a frequency of 10 kHz and a magnetic flux density of 1 T.

[0083] Test conditions: The sample size is 30 mm × 5 mm × 0.013 mm.

[0084] Result analysis: As can be seen from Table 1 - 4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the high-frequency loss of the obtained nanocrystalline soft magnetic alloy strip is 14 - 18 W / kg. Only the high-frequency loss of Example 1 is 18, and the others are all lower than 18. That is to say, Examples 2 to 12 are generally lower than 18 - 19 W / kg of the comparative examples, meeting the target range (10 - 20 W / kg).

[0085] Although the high-frequency losses of both the examples and the comparative examples are within the industry target range, a lower high-frequency loss means that the material performs better under high-frequency conditions, can reduce the energy loss of transformers and inductors, lower the economic cost, and further enhance the application value in related industries.

[0086] 5. Permeability Test Test method: Use an alternating current permeability measuring instrument to measure under the conditions of 1 kHz and 1 T.

[0087] Test conditions: The sample is 10 mm×10 mm ×0.013 mm.

[0088] Result analysis: As can be seen from Table 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the magnetic permeability of the obtained nanocrystalline soft magnetic alloy strip is between 55,000 and 64,000, which is significantly higher than that of the comparative example outside the scope of the present invention, which is between 48,000 and 52,000.

[0089] Since a higher magnetic permeability indicates that the material has excellent magnetic response characteristics at high frequencies, the material of the present invention is more suitable for applications in high-frequency transformers and motors.

[0090] 6. Tensile Strength and Elongation Test Test method: Use a material testing machine and conduct the test according to the standard of GB / T228.1-2010.

[0091] Test conditions: The sample is 10 mm×10 mm ×0.013mm, and the tensile rate is 10 mm / min.

[0092] Result analysis: As can be seen from Table 1-4, in Examples 1 to 12, when the content of each component element is within the scope of the present invention and each process condition is within the scope of the present invention, the tensile strength of the obtained nanocrystalline soft magnetic alloy strip is between 1200-1400 MPa, and the elongation is between 5-6%, both of which are higher than the tensile strength (1050-1100 MPa) and elongation (3.5-4%) of the comparative example.

[0093] This means that Examples 1 to 12 have high mechanical strength and ductility while maintaining excellent magnetic properties.

[0094] Generally speaking: From the perspective of electromagnetic properties, the electromagnetic properties of Examples 1 to 12 are significantly higher than those of existing products, including higher saturation magnetic induction intensity, lower coercivity, and higher magnetic permeability, indicating that they have greater application potential in high-frequency transformers, inductors, and motors.

[0095] From the perspective of mechanical properties, the improvement of the tensile strength and elongation of the alloy of the present invention proves that the examples maintain good mechanical properties while having high magnetic permeability and low loss.

[0096] From the perspective of process stability, under the same process conditions, the examples show better comprehensive performance, proving the rationality of the process scheme and the superiority of the material design.

[0097] In addition, the strips of the examples are suitable for the stators and rotors of high-frequency transformers, inductors, and motors, and can effectively reduce losses in high-frequency applications, improving the efficiency and stability of the equipment.

[0098] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high magnetic permeability nanocrystalline soft magnetic alloy, characterized in that, The chemical formula of the high magnetic permeability nanocrystalline soft magnetic alloy is Fe a Co b Ni c Ti d Si h B f R j M k (NbO) x ; Among them, R is a rare earth element, selected from at least one of La, Nd, and Y; M is a transition metal element, selected from at least one of Zr and Hf; a, b, c, d, h, f, j, k are respectively the atomic percentages of the corresponding components: 72 ≤ a ≤ 85, 2 ≤ b ≤ 5, 3 ≤ c ≤ 8, 1 ≤ d ≤ 2, 2 ≤ h ≤ 4, 2 ≤ f ≤ 4, 0.5 ≤ j ≤ 1, 0.5 ≤ k ≤ 2, 0.5 ≤ x ≤ 2, and the sum of the atomic percentages of all components is 100.

2. The high magnetic permeability nanocrystalline soft magnetic alloy according to claim 1, wherein The NbO is niobium oxide, introduced as a reactive substance during the smelting process, and reacts with boron and silicon to form a composite phase.

3. The high magnetic permeability nanocrystalline soft magnetic alloy according to claim 1, characterized in that the resistivity of the soft magnetic alloy is 150 - 180 μΩ•cm; and / or the saturation magnetic induction intensity of the soft magnetic alloy is 1.7 - 2.1 T; and / or the high-frequency loss of the soft magnetic alloy at a frequency of 10 kHz and a magnetic flux density of 1 T is 10 - 20 W / kg.

4. The high magnetic permeability nanocrystalline soft magnetic alloy according to claim 1, characterized in that, The nanocrystalline soft magnetic alloy is a high magnetic permeability nanocrystalline soft magnetic alloy strip.

5. A preparation method of a high magnetic permeability nanocrystalline soft magnetic alloy strip, characterized in that, It includes the following steps: Accurately weigh iron, cobalt, nickel, titanium, silicon, boron, rare earth elements, niobium oxide, and transition metal raw materials according to the alloy composition of the high magnetic permeability nanocrystalline soft magnetic alloy as described in any one of claims 1 - 3. The purity of all raw materials needs to be greater than 99%; After mixing the raw materials, heat them to 1800 - 2000 °C under the protection of inert gas and melt for 5 - 10 minutes to obtain a molten alloy; Cool the molten alloy through a centrifugal casting process to obtain alloy sheets; Clean and dry the alloy sheets, and ball-mill the dried alloy sheets to obtain refined particles; Load the refined particles into a mold and perform hot pressing at a temperature of 600 - 900 °C, with a forming pressure of 400 - 800 MPa and a forming time of 30 - 60 minutes to obtain a bulk material; Place the bulk material in a hot rolling mill and perform multi-pass rolling at a temperature of 500 - 700 °C to obtain a strip with a thickness of 10 - 14 μm; Perform continuous annealing treatment on the strip at 250 - 560 °C for 2 - 4 hours to obtain the high magnetic permeability nanocrystalline soft magnetic alloy strip.

6. The preparation method according to claim 5, characterized in that, The inert gas is argon with a purity greater than 99.99%.

7. The preparation method according to claim 5, wherein The rapid cooling of the molten alloy through the centrifugal casting process specifically includes: The molten alloy is rapidly cooled under vacuum conditions by centrifugal casting, and the cooling rate is greater than 10 4 K / s.

8. The preparation method according to claim 5, characterized in that, The drying specifically includes: performing in a vacuum drying furnace, with a drying temperature of 50 - 100 °C.

9. The preparation method according to claim 5, characterized in that, In the ball-milling process, the ball-milling medium is cemented carbide balls, and the ball-milling time is 1 - 2 hours.

10. The preparation method according to claim 5, characterized in that, In the hot pressing process, the forming pressure is 600 - 800 MPa, and the forming time is 45 - 60 minutes.

11. The preparation method according to claim 5, characterized in that, The number of rolling passes is not less than 5 times.

12. The preparation method according to claim 5, characterized in that, The continuous annealing treatment adopts a step annealing process. The first-stage temperature is 200 - 300 °C; the second-stage temperature is 300 - 400 °C; the third-stage temperature is 400 - 500 °C; the fourth-stage temperature is 520 - 560 °C; the treatment time for each stage does not exceed 1 hour, and the total continuous annealing time does not exceed 4 hours.

13. The preparation method according to claim 5, characterized in that, It further includes subjecting the high magnetic permeability nanocrystalline soft magnetic alloy strip to surface treatment using an electrolytic polishing technique.

14. Application of a high magnetic permeability nanocrystalline soft magnetic alloy strip prepared by the preparation method according to any one of claims 5 to 13 in a high-frequency transformer, an inductor, and stators and rotors of an electric motor.

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