Refined iron-based magnetically soft alloy and preparation method and application thereof

Abstract

The embodiment of the invention provides a refined iron-based magnetically soft alloy and a preparation method and application thereof, and the preparation method comprises the following steps: carrying out first ball milling treatment on an iron-based magnetically soft alloy with a first particle size to obtain first alloy powder; placing the alloy powder in a closed container, and carrying out hydrogenation-disproportionation treatment to obtain a metal hydride; the metal hydride is subjected to second ball milling treatment, and second alloy powder is obtained; placing the second alloy powder in another closed container, and carrying out dehydrogenation recombination to obtain third alloy powder; the third alloy powder is subjected to third ball milling treatment, and the refined iron-based soft magnetic alloy with the second particle size is obtained; the first particle size is larger than the second particle size. According to the preparation method of the refined iron-based magnetically soft alloy provided by the embodiment of the invention, the efficiency and damage bottleneck of pure mechanical ball milling are broken through by virtue of a chemical auxiliary refining mechanism of HDDR, high-yield, low-defect and easily-amplified fine powder preparation is realized, and a feasible path is provided for obtaining the high-performance refined iron-based magnetically soft alloy in batches.

Description

Technical Field

[0001] This application belongs to the field of soft magnetic material manufacturing technology, and in particular relates to a refined iron-based soft magnetic alloy, its preparation method and application. Background Technology

[0002] Iron-based soft magnetic alloy fine powders possess characteristics such as high frequency, low loss, high permeability, and easy molding, making them irreplaceable in high-efficiency, miniaturized electronic and power equipment. Applications include switching power supplies, photovoltaic inverter inductors, 5G base station RF inductors, and 3D printing of precision parts.

[0003] Currently, the main methods for refining iron-based soft magnetic alloys include gas atomization, water atomization, mechanical alloying, and chemical reduction. Among these, gas atomization produces fine powders with high sphericity and low oxygen content, but it suffers from high cost. Water atomization offers low manufacturing cost and a wide particle size range, but it suffers from high oxygen content and irregular morphology. Mechanical alloying uses simple equipment, but its refining efficiency is low and its oxygen content is high. Chemical reduction can produce nanoscale fine powders, but it is costly and difficult to mass-produce. Furthermore, none of these methods can mass-produce nanoscale fine powders of iron-based soft magnetic alloys; the collection of extremely fine powders relies on mechanical screening, but this still suffers from low yield and high powder loss.

[0004] As electronic products continue to develop towards intelligence, miniaturization, and thinness, it is foreseeable that small-sized iron-based soft magnetic alloys have huge application potential. Therefore, there is an urgent need to develop an efficient, low-cost powder refining process with mass production potential to meet the powder refining needs of iron-based soft magnetic alloys. Summary of the Invention

[0005] In view of this, the present application provides a refined iron-based soft magnetic alloy, its preparation method and application, to solve the technical problem that existing methods are still unable to mass-produce iron-based soft magnetic alloy nanoscale fine powder.

[0006] In a first aspect, embodiments of this application provide a method for preparing refined iron-based soft magnetic alloys, comprising: The first ball milling process was performed on the iron-based soft magnetic alloy with the first particle size to obtain the first alloy powder; The alloy powder was placed in a sealed container and subjected to hydrogenation-disproportionation treatment to obtain a metal hydride. The metal hydride is subjected to a second ball milling process to obtain a second alloy powder; The second alloy powder was placed in another sealed container and dehydrogenated and recombined to obtain the third alloy powder. The third alloy powder is subjected to a third ball milling process to obtain the refined iron-based soft magnetic alloy with a second particle size; wherein the first particle size is larger than the second particle size.

[0007] In some embodiments, the first particle size ranges from 1 to 500 μm. In some embodiments, the second particle size ranges from 100 nm to 1000 nm.

[0008] In some embodiments, the iron-based soft magnetic alloy with the first particle size includes a first soft magnetic alloy with a particle size of 1~10μm, a second soft magnetic alloy with a particle size of 10~50μm, and a third soft magnetic alloy with a particle size of 100~500μm.

[0009] In some embodiments, the mass ratio of the first soft magnetic alloy, the second soft magnetic alloy, and the third soft magnetic alloy is (0.5~1):(0.5~2):(7~9).

[0010] In some embodiments, the first ball milling process includes: A planetary ball mill was used, with a rotation speed of 200~400 r / min and a time of 5~8 h.

[0011] In some embodiments, the second ball milling process includes: The media used are zirconia ball mill jars and grinding balls, the rotation speed is 300~500 r / min, and the time is 10~30 h.

[0012] In some embodiments, the third ball milling process includes: The medium used is a stainless steel ball mill jar under nitrogen protection, with a rotation speed of 150~300 r / min and a time of 2~5 h.

[0013] In some embodiments, the hydrogenation-disproportionation treatment includes: evacuating to 10... -2 After Pa, inert gas is introduced to 1~2 MPa, and the air is removed by repeated steps. Then hydrogen is introduced and pressurized to 2~8 MPa. Adsorption is carried out at room temperature for 18~24 h to form metal hydrides. Then the pressure is released to 1~2 MPa and kept at 200~400℃ for 20~60 min.

[0014] In some embodiments, the heating temperature for the dehydrogenation and recombination is 700-850°C, the holding time is 20-40 minutes, and the process is carried out under a vacuum of 10... -2 The experiment was conducted under Pa conditions.

[0015] In some embodiments, the iron-based soft magnetic alloy of the first particle size is selected from at least one of iron-silicon-chromium alloy, iron-silicon-aluminum alloy, carbonyl iron powder, iron-aluminum alloy, and iron-based amorphous alloy.

[0016] In some embodiments, the sealed container is one of a high-pressure reactor, a vacuum sintering furnace, or a tubular reduction furnace.

[0017] Secondly, embodiments of this application provide a refined iron-based soft magnetic alloy, which is prepared using the preparation method described in the first aspect.

[0018] Thirdly, embodiments of this application provide an application of refined iron-based soft magnetic alloys, in which the refined iron-based soft magnetic alloys prepared by the preparation method described in the first aspect are applied to the manufacture of inductors, transformers, or electromagnetic shielding materials, as well as in additive manufacturing technology.

[0019] This application provides a refined iron-based soft magnetic alloy, its preparation method, and its application. It proposes a method for refining iron-based soft magnetic alloys by combining multi-stage ball milling with a hydrogenation-disproportionation-dehydrogenation and recombination (HDDR) process, effectively overcoming the difficulties of balancing cost, purity, efficiency, and mass production in existing technologies. The proposed method uses conventional micron-sized iron-based soft magnetic alloys as raw materials. The first stage involves surface activation through ball milling, followed by HDDR process in a closed environment to achieve hydrogen-induced embrittlement and phase structure decomposition of the material, significantly reducing subsequent ball milling energy consumption and avoiding excessive oxidation. The second stage involves efficient crushing in a hydride-brittle state to obtain fine powder. Dehydrogenation and recombination restore the soft magnetic phase structure and inhibit grain growth under vacuum conditions. Finally, a third stage of ball milling controls dispersibility and particle size distribution. The entire process requires no expensive atomization equipment or toxic chemical reagents, and the atmosphere is controllable throughout, effectively suppressing oxygen pollution. At the same time, by leveraging the chemical-assisted refining mechanism of HDDR, it overcomes the efficiency and damage bottlenecks of pure mechanical ball milling, achieving high yield, low defect, and easy scale-up fine powder preparation, providing a feasible path for mass production of high-performance refined iron-based soft magnetic alloys. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of the preparation method of refined iron-based soft magnetic alloys provided in the embodiments of this application. Detailed Implementation

[0022] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the embodiments of this application with unnecessary detail.

[0023] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0025] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0026] Furthermore, in the description of the embodiments and the appended claims of this application, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0027] In the description of embodiments in this application, references to "some embodiments" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in some embodiments," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiments, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" refers to two or more.

[0028] The first aspect of this application provides a method for preparing refined iron-based soft magnetic alloys, such as... Figure 1 As shown, it includes the following steps: S10. The iron-based soft magnetic alloy with the first particle size is subjected to a first ball milling process to obtain the first alloy powder; S20. The alloy powder is placed in a sealed container and subjected to hydrogenation-disproportionation treatment to obtain metal hydrides. S30. The metal hydride is subjected to a second ball milling process to obtain a second alloy powder; S40. Place the second alloy powder in another sealed container and perform dehydrogenation and recombination to obtain the third alloy powder. S50. The third alloy powder is subjected to a third ball milling process to obtain the refined iron-based soft magnetic alloy with a second particle size; wherein the first particle size is larger than the second particle size.

[0029] This application proposes a method for refining iron-based soft magnetic alloys by combining multi-stage ball milling with a hydrogenation-disproportionation-dehydrogenation and recombination (HDDR) process, effectively overcoming the challenges of balancing cost, purity, efficiency, and mass production in existing technologies. This method uses conventional micron-sized iron-based soft magnetic alloys as raw materials. The first stage involves surface activation through ball milling, followed by HDDR process in a closed environment to achieve hydrogen-induced embrittlement and phase structure decomposition, significantly reducing subsequent ball milling energy consumption and avoiding excessive oxidation. The second stage involves efficient crushing in a hydride-brittle state to obtain fine powder. Dehydrogenation and recombination restore the soft magnetic phase structure and inhibit grain growth under vacuum conditions. Finally, a third stage of ball milling controls dispersibility and particle size distribution. The entire process requires no expensive atomization equipment or toxic chemical reagents, and the atmosphere is controllable throughout, effectively suppressing oxygen pollution. Simultaneously, the chemical-assisted refining mechanism of HDDR overcomes the efficiency and damage bottlenecks of purely mechanical ball milling, achieving high yield, low defects, and easily scalable fine powder preparation, providing a feasible path for mass production of high-performance refined iron-based soft magnetic alloys.

[0030] In application, in step S10, the first particle size is 1~500μm. Using a wide range of initial particle sizes (1~500μm) is compatible with commonly used industrial atomizing powders or recycled materials, reducing costs. In a preferred embodiment, the iron-based soft magnetic alloy with the first particle size includes a D50 of 1~10μm. Further, the iron-based soft magnetic alloy with the first particle size includes a first soft magnetic alloy with a particle size of 1~10μm, a second soft magnetic alloy with a particle size of 10~50μm, and a third soft magnetic alloy with a particle size of 100~500μm. By further defining it into three particle size ranges (1~10μm, 10~50μm, 100~500μm) and controlling the mass ratio (0.5~1:0.5~2:7~9), the packing density and ball milling efficiency can be optimized—large particles provide skeletal support, while small particles fill voids and accelerate hydrogen diffusion. The multi-scale mixed powder forms a gradient hydrogen permeation path during hydrogenation, promoting overall disproportionation uniformity and avoiding localized over-hydrogenation or incomplete reaction.

[0031] It is worth mentioning that after the first ball milling treatment of the micron-sized iron-based soft magnetic alloy, microcracks were generated on the surface of the iron-based soft magnetic alloy. The characteristics of the microcracks are as follows: the width is about 10~100nm, which is much smaller than the original particle size; the depth can extend into the particle interior by 0.5~5μm, and they initiate along grain boundaries or hard phase interfaces, in the form of a network or radial pattern, which is especially prominent on the surface of large particles.

[0032] The presence of microcracks can significantly accelerate the hydrogen diffusion path and enhance the hydrogenation reaction kinetics. The bulk diffusion rate of hydrogen molecules in metals is slow, especially in dense alloys. Microcracks act as highly permeable channels, allowing hydrogen to quickly penetrate deep into the particle interior along the cracks, significantly shortening the time it takes for hydrogen to reach the core. Experiments show that the hydrogenation completion time of microcracked powder is effectively shortened compared to intact particles, and hydrogen absorption is more uniform. Stress concentration at the crack tip and local lattice distortion can reduce the activation energy of hydrogen adsorption and dissociation; therefore, effective hydrogenation can be achieved at lower hydrogen pressures, reducing equipment requirements and energy consumption. Without microcracks, hydrogen can only diffuse slowly from the surface inwards, leading to excessive hydrogenation or even pulverization of the outer layer, while the core remains unreacted. The microcrack network allows for three-dimensional hydrogen penetration, promoting simultaneous phase decomposition throughout the particle during the heating disproportionation stage, resulting in a product with highly uniform composition and grain size. Microcracks further weaken the particle structure on top of subsequent hydrogenation embrittlement; during the second ball milling, fracture preferentially propagates at the cracks, achieving low-energy, high-efficiency crushing and reducing ball milling time and energy input.

[0033] In some embodiments, the alloy particles of the three sizes each have their own function while also working synergistically. First, the large particles (100~500 μm) serve as the main framework, reducing excessive agglomeration and cold welding of powders during ball milling, maintaining the fluidity of the system, and forming macroscopic hydrogen channels during the hydrogenation stage to avoid hydrogen permeation obstruction caused by dense accumulation of fine powders. Second, the medium-sized particles (10~50 μm) act as a transitional bridge, enhancing the density of contact points between particles and providing a suitable specific surface area to balance the reaction rate and structural stability. Finally, the micro-fine particles (1~10 μm) have a high specific surface area and short diffusion paths, significantly accelerating hydrogen molecule adsorption and lattice diffusion, triggering local rapid disproportionation, thereby igniting the overall reaction.

[0034] In a preferred embodiment, the mass ratio of the first soft magnetic alloy, the second soft magnetic alloy, and the third soft magnetic alloy is (0.5~1):(0.5~2):(7~9). Specifically, the mass ratio of the first soft magnetic alloy, the second soft magnetic alloy, and the third soft magnetic alloy can be 1:1:8, 0.5:0.5:9, 1:2:7, etc. When these three are mixed in a specific ratio, a multi-scale compact packing structure is formed. This not only improves the pore connectivity of the initial powder bed but also constructs a gradient hydrogen concentration field and reaction front from the outside to the inside and from fine to coarse during the hydrogenation-disproportionation process, making the hydrogen permeation and phase change process more uniform and controllable. This effectively avoids common problems in single-particle-size systems, such as surface over-hydrogenation (leading to uncontrolled powder pulverization) or incomplete internal reactions (residual coarse grains), ultimately obtaining high-quality refined powder with uniform composition, fine grains, and consistent magnetic properties.

[0035] In some embodiments, the iron-based soft magnetic alloy with the first particle size is selected from at least one of iron-silicon-chromium alloy, iron-silicon-aluminum alloy, carbonyl iron powder, iron-aluminum alloy, and iron-based amorphous alloy. The iron-based soft magnetic alloy can be selected from iron-silicon-chromium (Fe-Si-Cr), iron-silicon-aluminum (Fe-Si-Al), carbonyl iron powder, iron-aluminum alloy (Fe-Al), iron-based amorphous alloy, etc., demonstrating the universality of this method, applicable to both crystalline and amorphous systems. It should be further noted that the diversity of alloy composition can adapt to different application scenarios. Iron-silicon-chromium and iron-silicon-aluminum have high resistivity and excellent high-frequency characteristics, suitable for switching power supply inductors; carbonyl iron powder has high purity and high permeability, suitable for high-frequency electromagnetic shielding; iron-aluminum alloy has both low loss and good corrosion resistance; iron-based amorphous alloys can achieve a controllable transformation from amorphous to nanocrystalline after HDDR treatment. This method can uniformly process these significantly different materials, indicating its good adaptability to both crystalline and amorphous structures. The above alloys all contain an iron matrix (such as α-Fe) that readily undergoes a reversible reaction with hydrogen, and can form metal hydrides (such as FeH) under mild conditions. x This provides a thermodynamic driving force for subsequent disproportionation. In particular, amorphous alloys are more prone to structural relaxation and phase separation during hydrogenation, which is actually beneficial for nanocrystal nucleation. The selected alloy system contains Si, Al, Cr and other additive elements with low vapor pressure and good chemical stability within the HDDR process temperature range (≤850℃). They will not volatilize in large quantities or generate harmful impurity phases during the dehydrogenation and recombination stage, thus ensuring compositional consistency and magnetic property stability.

[0036] In step S10, the first ball milling treatment includes: using a planetary ball mill at a rotation speed of 200~400 r / min for 5~8 h. Specifically, the rotation speed can be 200 r / min, 300 r / min, 400 r / min, etc., and the time can be 5 h, 6 h, 7 h, 8 h, etc. This initially breaks down large particles, exposing fresh surfaces and improving the activity of subsequent hydrogenation reactions; moderate ball milling avoids excessive cold welding or amorphization. Mechanism of action: Planetary ball milling provides high-energy impact and shear force, effectively breaking up the original aggregates, increasing the specific surface area, and creating conditions for hydrogen molecule adsorption and diffusion.

[0037] In applications, initial iron-based soft magnetic alloys (such as atomized powder or bulk crushed material) typically possess surface oxide films, agglomerates, or passivation layers. Ball milling at a moderate speed of 200–400 r / min for 5–8 hours effectively breaks down large particles, breaks up agglomerates, and exposes a clean, high-energy metal surface, significantly improving the adsorption activity and hydrogen diffusion rate of subsequent hydrogenation reactions. If the speed is too low (<200 r / min) or the time is too short (<5 h), activation is insufficient, and hydrogenation efficiency decreases; if the speed is too high (>400 r / min) or the time is too long (>8 h), cold welding, amorphization, or excessive temperature rise leading to pre-oxidation can easily occur, which is detrimental to the HDDR process. Although planetary ball milling is a high-energy ball milling method, it is only used as a "pretreatment" rather than the main refining method in this stage. A speed of 200–400 r / min combined with a time of 5–8 h can achieve initial particle size reduction (typically from hundreds of micrometers to tens of micrometers) with minimal lattice defect introduction. This "mild mechanical activation" improves reaction kinetics while avoiding severe dislocation buildup or amorphization—the latter hindering the orderly diffusion of hydrogen in the crystal lattice and affecting the uniformity and reversibility of the disproportionation reaction. After this stage, the powder transforms from irregular lumps or dense spheres into particles with certain angles but good dispersibility. This increases the specific surface area while maintaining sufficient fluidity, facilitating uniform spreading in closed containers (such as high-pressure reactors) and preventing uneven hydrogen permeation caused by localized accumulation, thus ensuring the macroscopic uniformity of the hydrogenation-disproportionation reaction.

[0038] In step S20, the sealed container is one of a high-pressure reactor, a vacuum sintering furnace, or a tubular reduction furnace. The sealed container can be a high-pressure reactor (suitable for hydrogenation), a vacuum sintering furnace, or a tubular reduction furnace (suitable for dehydrogenation), reflecting the flexibility of the process and its adaptability to industrialization.

[0039] In step S20, the hydrogenation-disproportionation process includes: evacuating to 10... -2 After passing through a pressure of 1-2 MPa, an inert gas is introduced to purge the air repeatedly. Then, hydrogen is introduced and pressurized to 2-8 MPa. Adsorption occurs at room temperature for 18-24 hours to form metal hydrides. The pressure is then released to 1-2 MPa, and the mixture is held at 200-400℃ for 20-60 minutes. Hydrogen atoms diffuse into the crystal lattice to form hydrides, inducing lattice expansion and embrittlement. Subsequently, a disproportionation reaction occurs during the heating phase, decomposing the original coarse grains into nanoscale new phases. The HDDR process is essentially a destruction-reconstruction mechanism, utilizing hydrogen-induced phase transitions to achieve grain refinement while maintaining compositional consistency, which is superior to the impurities introduced by pure mechanical crushing.

[0040] In application, vacuum is drawn to 10. -2Pa effectively removes most of the air from the container; then, an inert gas (such as Ar or N2) is introduced to 1-2 MPa and then depressurized, repeated multiple times, using the pressurization-depressurization flushing principle to forcefully remove residual oxygen, moisture, and volatile impurities. The oxygen partial pressure of the system is reduced to the ppm level, avoiding the formation of oxides during subsequent hydrogenation. These oxides not only hinder hydrogen diffusion but also become pinning centers for magnetic degradation. Introducing hydrogen at 2-8 MPa at room temperature and allowing it to adsorb for a long time (18-24 h) ensures that hydrogen molecules diffuse fully into the interior of the alloy particles; under these conditions, iron-based alloys (such as α-Fe) undergo a reversible reaction with H2 to form metal hydrides, accompanied by significant lattice expansion and the generation of internal stress. Controlled pressure and temperature disproportionation (depressurization to 1-2 MPa, holding at 200-400℃ for 20-60 min) triggers controlled phase decomposition. After adsorption, the pressure is released to 1-2 MPa (not completely to atmospheric pressure) to reduce system pressure, thus promoting hydrogen activity changes while maintaining a certain hydrogen atmosphere to prevent premature dehydrogenation. The temperature is then raised to 200-400℃ and held to induce a disproportionation reaction in the hydride. The entire process is carried out in a closed container, producing no acid or alkali waste liquids or organic solvents, meeting green manufacturing requirements. Compared to chemical reduction or plasma methods, energy consumption is significantly reduced. Hydrogen can be recycled, further reducing costs.

[0041] In step S30, the second ball milling process includes: using a zirconia ball mill jar and milling balls as the medium, a rotation speed of 300~500 r / min, and a time of 10~30 h. Specifically, the rotation speed can be 300 r / min, 400 r / min, 500 r / min, etc., and the time can be 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, 25 h, 28 h, 30 h, etc. A rotation speed of 300~500 r / min provides sufficient impact and shear force to break brittle hydrides, but avoids local overheating that could lead to premature hydrogen desorption or amorphization; a time of 10~30 h ensures sufficient refinement to the target size. Experiments have shown that exceeding 30 h can easily induce slight agglomeration or surface oxidation (even under inert gas), while less than 10 h results in a coarser particle size distribution and poor uniformity. Hydrogenation significantly enhances the brittleness of the material, enabling efficient refining to submicron levels with low energy consumption. The use of zirconium oxide media avoids iron contamination, ensuring product purity. Prolonged high-speed ball milling further breaks down the hydrogenation-disproportionation products, yielding uniform fine powder that provides a highly active precursor for subsequent dehydrogenation and recombination.

[0042] In applications, after hydrogenation-disproportionation treatment, iron-based alloys are transformed into metallic hydrides and novel nanoscale phases generated by disproportionation. These hydrides exhibit lattice expansion, weakened bonding forces, significant embrittlement, and reduced hardness, making them brittle. Ball milling under these conditions, even at medium to high speeds (300–500 r / min), can achieve highly efficient crushing with relatively low energy input, rapidly refining powder particle sizes from micrometers to submicrometers or even nanometers.

[0043] If ball milling of the same intensity is performed directly in the unhydrogenated state, higher energy and longer time are required, accompanied by severe cold welding, temperature rise, and lattice distortion. However, this solution, through a "soften first, then pulverize" strategy, significantly improves the refining efficiency and reduces structural defects. The powder obtained after the second ball milling has a high specific surface area, uniform nanoscale, and abundant grain boundaries. In the subsequent dehydrogenation and recombination process: the hydrogen desorption path is shorter, and dehydrogenation is more thorough; the driving force for atomic rearrangement is stronger, which is conducive to the formation of fine and uniform recrystallized grains; abnormal grain growth is suppressed, and ultimately a high-density, low-coercivity soft magnetic structure is obtained.

[0044] In step S40, the second alloy powder is placed in another sealed container for dehydrogenation and recombination to obtain the third alloy powder. The dehydrogenation and recombination is carried out at a heating temperature of 700–850°C for 20–40 minutes under a vacuum of 10⁻² Pa. Under this high-temperature vacuum environment, hydrogen is completely removed, and atomic rearrangement restores the soft magnetic alloy phase. Furthermore, because the precursor is a nanostructure, the recombined material retains fine grains, significantly reducing coercivity and hysteresis loss. The dehydrogenation process is accompanied by recrystallization, but grain growth is suppressed due to the original nanoscale, achieving the dual goals of fine grain strengthening and soft magnetic optimization.

[0045] In applications, in high vacuum (10 -2 Under conditions of 700-850°C, the extremely low partial pressure of hydrogen greatly promotes the desorption reaction of hydrogen in metal hydrides. Temperatures of 700-850°C provide sufficient activation energy for hydrogen atom diffusion and escape, ensuring near-complete dehydrogenation within 20-40 minutes. If residual hydrogen is not removed, it will slowly release during subsequent applications, leading to material volume expansion, permeability drift, and even structural cracking. Thorough dehydrogenation ensures the long-term stability and consistent magnetic properties of the powder. Small grain size significantly reduces coercivity and increases high-frequency permeability while reducing eddy current losses, meeting the requirements of miniaturized electronic devices for high-frequency, low-loss materials. The finished powder has an oxygen content controllable to <500 ppm, a clean surface, and is suitable for demanding applications (such as GHz-level EMI shielding and high-frequency inductors).

[0046] In step S50, the third ball milling process includes: using a stainless steel ball mill jar under nitrogen protection, rotating at a speed of 150~300 r / min, and for a time of 2~5 h. Specifically, the rotation speed can be 150 r / min, 200 r / min, 300 r / min, etc., and the time can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc. Light ball milling adjusts the final particle size distribution, eliminates agglomeration, and obtains a finished powder with good flowability and uniform dispersion; nitrogen protection prevents oxidation and maintains high magnetic permeability. Short-time low-energy ball milling is only used for deagglomeration to avoid lattice damage and ensure stable magnetic properties.

[0047] In applications, although the third alloy powder, after dehydrogenation and recombination, already possesses nano / submicron-sized grains, its high specific surface area and surface energy make it highly susceptible to hard agglomeration or sintering neck connections, resulting in an actual dispersed particle size much larger than the primary grain size. The third ball milling, performed at a lower speed (150–300 r / min) and for a shorter time (2–5 h), provides mild mechanical treatment. Its primary purpose is not to further reduce grain size, but rather to break up soft agglomerates, improve powder dispersibility, and bring the final product's actual particle size closer to the target range (e.g., 100–1000 nm), achieving a narrow and uniform particle size distribution. Omitting this step results in poor powder flowability and low compression density, making it difficult to meet the requirements of subsequent molding processes (e.g., magnetic core pressing or 3D printing). Conversely, excessively high parameters (e.g., speed > 300 r / min or time > 5 h) may cause lattice damage and introduce defects, ultimately degrading magnetic properties. Iron-based soft magnetic alloys are extremely sensitive to surface oxidation—even a trace oxide layer can significantly increase high-frequency eddy current losses and reduce permeability. The third ball milling is conducted under a high-purity nitrogen protective atmosphere, which effectively isolates oxygen and moisture, preventing surface oxidation of the powder in the final processing stage. This is especially crucial for highly refined powders where oxidation resistance is paramount. This measure ensures that the finished powder has low oxygen content, a clean surface, and excellent high-frequency soft magnetic properties.

[0048] In step S50, the second particle size ranges from 100 nm to 1000 nm. Through the above steps, a refined iron-based soft magnetic alloy with a second particle size is obtained, achieving an effective leap from the micrometer scale to the nanometer / submicrometer scale.

[0049] It should be noted that the three ball milling processes in this invention are not isolated operations, but rather form a highly synergistic and progressive process system around the logical main line of activation-refinement-preparation, jointly achieving the core objective of efficiently, cleanly, and controllably preparing high-performance nano / submicron-sized iron-based soft magnetic alloy powders. The first ball milling focuses on surface activation and preliminary crushing, creating highly reactive precursors for hydrogenation; the second ball milling performs deep refinement under the hydride embrittlement state, utilizing material state changes to achieve low-energy and high-efficiency crushing; the third ball milling focuses on deagglomeration and surface protection, optimizing powder dispersibility and application adaptability. Each of the three processes performs its specific function, avoiding the oxidation, cold welding, amorphization, or magnetic property degradation problems caused by traditional single high-intensity ball milling. Furthermore, the three ball milling processes are deeply coupled with the HDDR process, forming a mechanochemical synergistic refinement mechanism, with the three ball milling processes placed at the three key nodes before, during, and after the HDDR process. The first ball milling improves hydrogenation efficiency, the second ball milling amplifies the hydrogen-induced embrittlement effect, and the third ball milling consolidates the dehydrogenation and recombination results. Throughout the entire process, impurity introduction and structural damage are controlled to ensure magnetic properties. The first and second ball mills utilize planetary ball mills and zirconia media, respectively, to minimize Fe contamination. Although the third ball mill uses a stainless steel jar, its low strength and nitrogen protection minimize risks. The rotation speed and time at each stage are precisely matched to the material state to avoid the accumulation of lattice defects caused by over-processing. These three processes work together to ensure high purity, low oxygen content, and few defects in the final powder, resulting in low coercivity, high permeability, and excellent high-frequency characteristics. The final product not only has a particle size within the ideal range of 100–1000 nm but also possesses good compressibility, dispersibility, and process compatibility, making it suitable for high-end applications such as inductors, transformers, electromagnetic shielding, and additive manufacturing.

[0050] This application also provides a refined iron-based soft magnetic alloy, which is prepared using the preparation method described in the first aspect.

[0051] The refined iron-based soft magnetic alloy provided in this application produces alloy powder with a stable particle size in the range of 100 nm to 1000 nm, which is much smaller than that of conventional atomized powder. Furthermore, the particle size distribution is narrow and the degree of agglomeration is low. This submicron / nanoscale structure can effectively suppress eddy current losses at high frequencies, meeting the urgent need for small-sized magnetic materials in high-frequency, high-power-density electronic devices such as 5G communications, fast-charging power supplies, and miniature inductors.

[0052] This application also provides an application of refined iron-based soft magnetic alloys, in which the refined iron-based soft magnetic alloys prepared by the preparation method described in the first aspect are applied to the manufacture of inductors, transformers or electromagnetic shielding materials and additive manufacturing technology.

[0053] The effects of refined iron-based soft magnetic alloys in inductors and high-frequency transformers include: the alloy powder particle size is 100~1000nm, much smaller than traditional micron-sized powders, effectively suppressing eddy current effects; at the same time, the fine and uniform grains significantly reduce hysteresis losses. High saturation magnetic induction combined with low loss characteristics allows the magnetic core to operate at higher frequencies and smaller volumes, meeting the high power density and thin-film requirements of 5G base station power supplies, fast charging adapters, and automotive OBCs. Low oxygen content and a clean interface reduce permeability temperature drift, ensuring stable device performance over a wide temperature range. In electromagnetic shielding materials, the nano-sized powder, with its high permeability and natural resonant frequency shift towards the GHz band, can effectively absorb electromagnetic interference in the 1~18GHz range, achieving a shielding effectiveness of 35~50dB, superior to conventional micron-sized iron powders. The powder exhibits excellent dispersibility and small particle size, making it easy to uniformly fill flexible matrices such as silicone, epoxy resin, or TPU. The resulting shielding coatings or films combine flexibility, lightweight design, and high shielding performance, making them suitable for wearable devices, flexible circuits, and mobile phone frames. In additive manufacturing applications, while the powder's sphericity is not perfect, its narrow particle size distribution and good flowability make it suitable for laser powder bed melting or binder jetting processes, with no obvious pores or cracks.

[0054] By applying the refined iron-based soft magnetic alloy prepared in this invention to the above-mentioned fields, not only are its material advantages of nanoscale, low loss, high purity and good process adaptability fully utilized, but it also promotes the development of electronic components towards high frequency, miniaturization, flexibility and structural-functional integration, which has significant technological advancement and industrialization value.

[0055] Example Example 1 This application provides a method for preparing a preferred iron-based soft magnetic alloy, comprising the following steps: S10. Ball milling of iron-silicon-chromium soft magnetic alloy with D50=6μm for 6h produces first alloy powder with microcracks. S20. Place the ball-milled iron-silicon-chromium soft magnetic alloy from step S10 into a high-pressure reactor and evacuate to 10°C. - 2 The pressure was increased to 2 MPa, then nitrogen was introduced to remove the air from the container, and a vacuum was drawn. This process was repeated three times to remove the air from the container. Then hydrogen was introduced to pressurize the container to 6 MPa, and it was left at room temperature for 24 hours to allow the hydrogen to be saturated and adsorbed, forming a certain amount of metal hydrides. Subsequently, the pressure was released to 2 MPa, and the container was kept at 350°C for 50 minutes to complete the hydrogenation-disproportionation process, which improved the brittleness of the powder. S30. The disproportionation product from step S20 is ball-milled for 20 hours to obtain the second alloy powder. S40. Place the powder from step S20 into a high-pressure reactor and evacuate to 10°C. -2Pa was subjected to dehydrogenation and recombination at 750℃ for 30 min to obtain the third alloy powder; S50. The powder from step S40 is ball-milled for 5 hours to break up the agglomerated powder particles and obtain iron-silicon-chromium soft magnetic alloy powder with a particle size D50=0.76μm.

[0056] Example 2: This application provides a method for preparing refined iron-based soft magnetic alloys, comprising the following steps: S10. Ball milling of iron-silicon-chromium soft magnetic alloy with D50=10μm for 8 hours to produce first alloy powder with microcracks; S20. Place the ball-milled iron-silicon-chromium soft magnetic alloy from step S10 into a high-pressure reactor and evacuate to 10°C. - 2 The pressure was increased to 2 MPa, then nitrogen was introduced and the pressure was increased to 2 MPa. A vacuum was then created, and this process was repeated three times to remove air from the container. Hydrogen was then introduced and pressurized to 8 MPa. The container was left at room temperature for 24 hours to allow for hydrogen saturation and the formation of a certain amount of metal hydrides. The pressure was then released to 3 MPa and held at 400°C for 60 minutes to complete the hydrogenation-disproportionation process, which improved the powder's brittleness. S30. The disproportionation product from step S20 is ball-milled for 30 hours to obtain the second alloy powder. S40. Place the powder from step S20 into a high-pressure reactor and evacuate to 10°C. -2 Pa was subjected to dehydrogenation and recombination at 750℃ for 30 min to obtain the third alloy powder; S50. The powder from step S40 is ball-milled for 5 hours to break up the agglomerated powder particles and obtain iron-silicon-chromium soft magnetic alloy powder with a particle size D50=0.91μm.

[0057] Examples 3-5 The results are basically the same as in Example 1, except that the particle size range and weight ratio of the first-size iron-based soft magnetic alloy are different, as shown in the table below:

[0058] A higher proportion of large particles (as in Example 3) results in a coarser final particle size (0.95 μm). This is because large particles are difficult to refine completely, and coarse phase residues may remain. Increasing the proportion of small / medium particles (as in Example 5) leads to a finer final particle size (0.6 μm). This is because small particles are inherently easier to refine and are more readily disproportionated in HDDR. The optimal formulation trend is that increasing the proportion of small (1~10 μm) and medium (10~50 μm) particles is beneficial for obtaining a finer and more uniform final powder.

[0059] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0060] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of the embodiments of this application.

Claims

1. A method for preparing refined iron-based soft magnetic alloys, characterized in that, Includes the following steps: The first ball milling process was performed on the iron-based soft magnetic alloy with the first particle size to obtain the first alloy powder; The alloy powder was placed in a sealed container and subjected to hydrogenation-disproportionation treatment to obtain a metal hydride. The metal hydride is subjected to a second ball milling process to obtain a second alloy powder; The second alloy powder was placed in another sealed container and dehydrogenated and recombined to obtain the third alloy powder. The third alloy powder is subjected to a third ball milling process to obtain the refined iron-based soft magnetic alloy with a second particle size; wherein the first particle size is larger than the second particle size.

2. The preparation method according to claim 1, characterized in that, The first particle size ranges from 1 to 500 μm; and / or, The second particle size ranges from 100 nm to 1000 nm.

3. The preparation method according to claim 1, characterized in that, The first particle size of the iron-based soft magnetic alloy includes a first soft magnetic alloy with a particle size of 1~10μm, a second soft magnetic alloy with a particle size of 10~50μm, and a third soft magnetic alloy with a particle size of 100~500μm.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the first soft magnetic alloy, the second soft magnetic alloy, and the third soft magnetic alloy is (0.5~1):(0.5~2):(7~9).

5. The preparation method according to claim 1, characterized in that, The first ball milling process includes: A planetary ball mill is used, with a rotation speed of 200~400 r / min and a time of 5~8 h; and / or, The second ball milling process includes: The media used are zirconia ball mill jars and grinding balls, the rotation speed is 300~500 r / min, and the time is 10~30 h; and / or, The third ball milling process includes: The medium used is a stainless steel ball mill jar under nitrogen protection, with a rotation speed of 150~300 r / min and a time of 2~5 h.

6. The preparation method according to claim 1, characterized in that, The hydrogenation-disproportionation treatment includes: evacuating to 10... - 2 After Pa, inert gas is introduced to 1~2 MPa, and the air is removed by repeated steps. Then hydrogen is introduced and pressurized to 2~8 MPa. Adsorption is carried out at room temperature for 18~24 h to form metal hydrides. Then the pressure is released to 1~2 MPa and kept at 200~400℃ for 20~60 min.

7. The preparation method according to claim 1, characterized in that, The dehydrogenation and recombination process is carried out at a heating temperature of 700-850°C for 20-40 minutes under a vacuum of 10°C. -2 The experiment was conducted under Pa conditions.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The first particle size of the iron-based soft magnetic alloy is selected from at least one of iron-silicon-chromium alloy, iron-silicon-aluminum alloy, carbonyl iron powder, iron-aluminum alloy, and iron-based amorphous alloy; and / or, The sealed container is one of a high-pressure reactor, a vacuum sintering furnace, or a tubular reduction furnace.

9. A refined iron-based soft magnetic alloy, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. An application of refined iron-based soft magnetic alloys, characterized in that, The refined iron-based soft magnetic alloy prepared by the preparation method according to any one of claims 1 to 8 is applied to the manufacture of inductors, transformers or electromagnetic shielding materials and in additive manufacturing technology.

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