Novel medium-entropy FeCoNi-based soft magnetic material and preparation method thereof

Abstract

The invention provides a novel medium-entropy FeCoNi-based soft magnetic material and a preparation method thereof, and belongs to the technical field of soft magnetic materials. The material comprises the following chemical components in atomic ratio: 25-35% of iron (Fe), 25-35% of cobalt (Co), 25-35% of nickel (Ni), 1-5% of aluminum (Al), 1-5% of titanium (Ti), 0.1-2% of niobium (Nb) and the balance of inevitable impurities. The invention further provides a preparation method of the novel medium-entropy FeCoNi-based soft magnetic material, through the synergistic effect of rapid solidification and heat treatment, the problems of uneven material components, stress concentration, insufficient second-phase regulation and control and the like caused by a traditional rapid solidification technology are solved, and a soft magnetic thin strip uniform in organization structure and stable in performance can be obtained. The material and the preparation method are suitable for large-scale production of high-performance power electronic devices, and have wide application prospects in the fields of new energy automobile motors, 5G communication base station radio frequency devices, aerospace power systems, high-efficiency transformers and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic materials, and in particular relates to a novel medium-entropy FeCoNi-based soft magnetic material and a preparation method thereof. Background Art

[0002] Soft magnetic materials are magnetic materials that easily magnetize and demagnetize in weak magnetic fields. As core building blocks for efficient electromagnetic energy conversion and transmission, they play a vital role in modern power electronics, automatic control, and information technology. From everyday electronic devices to large-scale industrial equipment, from traditional power systems to emerging new energy industries, the performance of soft magnetic materials directly impacts equipment efficiency, energy consumption, stability, and the degree of miniaturization and lightweighting. Traditional soft magnetic materials have numerous limitations. For example, silicon steel sheets experience a sharp increase in hysteresis and eddy current losses in high-frequency applications, limiting their use in high-frequency power electronics. Ferrites are suitable for high-frequency applications, but their low saturation magnetic induction makes them difficult to meet the demands of high-power and high-current applications. Permalloy offers high permeability but relatively low saturation magnetization and Curie temperature, as well as high cost. Therefore, developing new soft magnetic materials to meet growing market demand is a pressing task.

[0003] The rapid development of emerging technologies has placed increasingly stringent demands on the performance of soft magnetic materials. On the one hand, soft magnetic materials are required to have higher saturation magnetization to improve the energy conversion efficiency of equipment under high-power conditions and meet the high power density requirements of new energy vehicle motors, aerospace power systems, and other applications. On the other hand, they are required to have lower magnetic losses under high-frequency operating conditions to reduce equipment heat generation, improve energy utilization, and adapt to the application scenarios of magnetic components such as high-frequency transformers and inductors in 5G communication base stations. At the same time, soft magnetic materials are also expected to have high magnetic permeability to enhance the response speed and transmission efficiency of electromagnetic signals, and be used in equipment such as high-performance sensors and communication filters.

[0004] Iron-cobalt-nickel-based alloys, with their advantages of high saturation magnetization and good magnetic permeability, have become a key research and development direction for new soft magnetic materials. However, the production of iron-cobalt-nickel-based alloys using traditional preparation methods such as casting and powder metallurgy has many problems: First, the coarse grains and slow solidification rate of conventional casting lead to severe component segregation and uneven diffusion of elements during alloy solidification, resulting in poor material performance consistency and reduced magnetic permeability; second, low production efficiency. The casting and powder metallurgy processes are complex, energy consumption is high, and the yield rate is low, making large-scale industrial production difficult.

[0005] Rapid solidification technology is a method of solidifying metal or alloy in a short time by rapid cooling, which can obtain materials with special structure and properties. The belt throwing method is a common method of rapid solidification technology. The molten metal liquid flow is sprayed onto the surface of the high-speed rotating cooling roller, so that the metal liquid is 10 5 -10 6 High-speed cooling at 100°C / s effectively inhibits grain growth and forms a refined grain structure. However, the simple belt-spinning method lacks systematic control over alloy composition uniformity, grain size gradient, and second-phase precipitation dynamics, limiting the material's performance.

[0006] Heat treatment is a process that modifies the microstructure and physical properties of metals (and alloys) through a controlled process of heating, holding, and cooling. Its core principle is based on solid-state phase transformation and atomic diffusion. By adjusting temperature and time parameters, precise control of material properties such as hardness, toughness, and strength can be achieved. The metal is first heated to a critical temperature, allowing atoms to gain sufficient energy to break existing bonds. Holding ensures the phase transformation is complete and the composition is homogenized. During this stage, atoms diffuse to a stable state with the lowest energy. During the cooling phase, the cooling rate determines the final microstructure. Heat treatment plays a key role in optimizing the properties of soft magnetic materials, primarily by manipulating microstructural features such as crystal structure, grain size, internal stress, and phase composition. Annealing is used to adjust grain size. High-temperature annealing forms coarse grains, increases magnetic domain size, and significantly reduces iron loss and coercivity. Stress relief annealing below the recrystallization temperature eliminates internal stresses introduced by cold working and restores magnetic permeability. For ordered alloys, annealing in a specific temperature range promotes atomic ordering and significantly improves magnetic permeability.

[0007] At present, there are relatively few studies on the preparation of iron-cobalt-nickel based soft magnetic materials using rapid solidification coupled heat treatment process. The research on the stripping and heat treatment preparation of iron-cobalt-nickel based soft magnetic materials has problems such as unreasonable composition design and unoptimized process parameters, which makes it difficult to fully exert the material performance and cannot meet the urgent demand of modern industry for high-performance soft magnetic materials.

[0008] Therefore, it is still an urgent problem to prepare iron-cobalt-nickel based soft magnetic materials with excellent comprehensive performance by rationally designing material composition and optimizing preparation process. The development of new soft magnetic materials and the optimization of preparation process are of great practical significance. Summary of the Invention

[0009] The present invention aims to provide a novel medium-entropy FeCoNi-based soft magnetic material having excellent soft magnetic properties such as high saturation magnetization (Ms), low coercivity (Hc), and high magnetic permeability (μi); and at the same time, to provide a method for preparing the material. By using vacuum stripping technology and heat treatment processes, the problems of component segregation, stress concentration, coarse grains, and insufficient second phase control in traditional processes are solved, thereby achieving comprehensive improvement in the performance of soft magnetic materials and industrial production.

[0010] To achieve the above objectives, the present invention provides the following technical solutions:

[0011] A new medium-entropy FeCoNi-based soft magnetic material has the following chemical composition, calculated by atomic ratio: iron (Fe) 25-35%, cobalt (Co) 25-35%, nickel (Ni) 25-35%, aluminum (Al) 1-5%, titanium (Ti) 1-5%, niobium (Nb) 0.1-2%, and the balance being unavoidable impurities.

[0012] Iron, as a matrix element, provides a high saturation magnetic induction intensity, laying the foundation for the material's magnetic and mechanical properties. Cobalt can increase the material's Curie temperature and magnetic permeability. Specifically, the cobalt atom has a large magnetic moment, which synergizes with iron and nickel to enhance the material's magnetic properties, improving energy conversion efficiency in high-power electrical equipment. Nickel helps improve the material's processing properties and corrosion resistance, making the material perform better in electromagnetic signal processing and easier to process and shape. At the same time, appropriate amounts of aluminum, titanium, and niobium are added. Aluminum refines the grain size, increasing the material's hardness and resistivity. Titanium and niobium easily form fine carbides or nitrides, which act as dispersion strengthening, inhibiting grain growth, enhancing thermal stability, and ensuring the material's stable performance in high-temperature environments. These elements work together to optimize the material's properties.

[0013] Preferably, the saturation magnetization intensity Ms of the material is ≥270 emu / g, which can meet the requirements of high-power equipment for high saturation magnetic induction intensity. For example, in new energy vehicle motors, it can increase the output power and torque of the motor; under the conditions of 100kHz and 1 T, the magnetic loss is ≤320 W / kg, which effectively reduces energy loss at high frequency, reduces equipment heating, and improves energy utilization efficiency, making it suitable for components such as high-frequency transformers; the initial magnetic permeability μi is ≥6000, which can improve electromagnetic conversion efficiency and accelerate electromagnetic signal response speed. When used in sensors, it can improve detection sensitivity. The corrosion potential of the material in a 3.5% mass fraction NaCl solution is Ecorr ≥-300 mV, and the corrosion current density Icorr ≤3.5×10 -6 A / cm 2 , good corrosion resistance. In addition, the material also has good thermal stability and mechanical properties, can adapt to complex working conditions, such as in the high temperature and vibration environment of aerospace.

[0014] The present invention also provides a method for preparing the novel medium-entropy FeCoNi-based soft magnetic material, which is based on a rapid solidification technology coupled with a heat treatment process, comprising the following steps:

[0015] S1. Raw material pretreatment: Select electrolytic iron, electrolytic cobalt, electrolytic nickel metal raw materials with a purity of ≥99.5%, as well as pure aluminum, pure titanium, and pure niobium as additive raw materials, mix the weighed raw materials, and then dry them;

[0016] S2. Alloy melting: Place the dried raw materials into a vacuum arc melting furnace, evacuate the furnace, and introduce high-purity argon as a protective gas for vacuum melting;

[0017] S3, strip forming: a single-roll strip forming machine is used for the forming operation. The smelted alloy liquid is sprayed onto the surface of the high-speed rotating copper roller of the single-roll strip forming machine. The alloy liquid is rapidly cooled and solidified on the surface of the copper roller to form a metal strip.

[0018] S4, strip forming post-processing: the metal strip is pickled, washed and dried in sequence, and cut into appropriate sizes;

[0019] S5. Heat treatment: The slit metal strip is placed in a tube furnace for heat treatment, and the strip is taken out after cooling;

[0020] S6. Post-processing: sequentially pickling, water washing and vacuum drying the heat-treated thin strip to obtain the novel medium-entropy FeCoNi-based soft magnetic material.

[0021] Preferably, in step S1, mixing is performed in a mixer at a speed of 100 r / min for 60 minutes to ensure that the raw materials are fully and evenly mixed. Drying is performed in a vacuum drying oven at a temperature of 70-100°C for 1.5-3 hours to remove moisture and impurities adsorbed on the surface of the raw materials, avoid defects such as pores during the smelting process, and ensure alloy quality.

[0022] Preferably, in step S2, the dried raw materials are placed in a vacuum arc melting furnace, the furnace door is closed, the vacuum system is started, and the pressure in the furnace is pumped down to 1×10 -3 The pressure is below Pa, and air and impurity gases are excluded. The purpose of introducing high-purity argon is to prevent the alloy from oxidizing during the smelting process. The flow rate of high-purity argon is 8-12 L / min.

[0023] Preferably, in step S2, the vacuum arc melting power is 8-12 kW, the number of melting cycles is 6-8, and each melting cycle lasts 3-5 minutes. Repeated melting ensures uniform alloy composition. After melting, the alloy is allowed to stand in the crucible for 1-2 minutes to allow the slag to float to the surface for subsequent removal.

[0024] Preferably, in step S3, the diameter of the copper roller of the single-roller strip spinning machine is 300-400 mm, and the surface roughness Ra is ≤ 0.8 μm to ensure the surface quality of the thin strip; the copper roller speed is controlled at 10-30 m / s, and the roller surface temperature is controlled at 20-80 ° C, which is precisely adjusted by a frequency converter.

[0025] Preferably, in step S3, the alloy liquid melted in the quartz tube is sprayed onto the surface of the high-speed rotating copper roller through a circular nozzle using high-pressure argon gas at 0.8-1.2 MPa. The nozzle diameter is 2-4 mm, the distance from the copper roller surface is 1-3 mm, the injection pressure of the alloy liquid is 0.1-0.5 MPa, and the injection angle is 30-60°. The cooling rate of the alloy liquid on the copper roller surface is 10 5 -10 6 ℃ / s, the thickness of the ribbon is 20-50 μm.

[0026] Preferably, in step S4, pickling is to immerse the metal strip in a dilute hydrochloric acid solution with a mass fraction of 5-10% for pickling for 3-5 minutes to remove the surface oxide layer and impurities. Water washing is to rinse with deionized water until neutral to avoid the influence of residual acid on the material properties. Drying is to place the rinsed strip in a vacuum drying oven and dry it at a temperature of 60-70 ° C for 2-3 hours to remove moisture. Slitting is to cut the dried strip into suitable sizes with precision slitting equipment according to actual use requirements to facilitate subsequent heat treatment. The slitting size is usually 50 cm.

[0027] Preferably, in step S5, the slit metal strip is placed in a crucible, which is then pushed into a tube furnace. The furnace plug and sealing flange are installed, and the argon bottle is opened to vent the gas in the furnace chamber. The initial heat treatment temperature is 50°C, and the material is heat treated at 700-900°C at a heating rate of 5-15°C / min for 1-3 hours. The furnace is then cooled to 50°C, and the strip is removed after cooling.

[0028] Preferably, in step S6, pickling is performed by immersing the heat-treated metal strip in a 5-10% by mass dilute hydrochloric acid solution for 3-5 minutes to remove the surface oxide layer and impurities. Water washing is performed by rinsing with deionized water until neutral to prevent residual acid from affecting material properties. Drying is performed by placing the rinsed strip in a vacuum drying oven at 60-70°C for 2-3 hours to remove moisture, and finally vacuum packaging.

[0029] The present invention has the following beneficial effects:

[0030] 1. Significant performance improvement: Compared with traditional iron-cobalt-nickel-based soft magnetic materials, the soft magnetic material of the present invention has a 10-20% increase in saturation magnetization, a 20-30% decrease in magnetic loss, and a 15-25% increase in initial magnetic permeability, significantly improving overall soft magnetic properties. The corrosion potential is increased by 10-20%, and the corrosion current density is reduced by 15-30%, better meeting the needs of modern industry for high-performance soft magnetic materials.

[0031] 2. Preparation process advantages: The rapid solidification technology coupled with the heat treatment process preparation method enables the alloy liquid to solidify in an extremely short time, obtaining a refined grain structure and uniform composition distribution. The subsequent heat treatment further enhances the material properties, and the production efficiency is increased by 3-5 times compared with the traditional process. Through the precise process parameters in the production process, such as the cooling roller speed, roller surface temperature, alloy liquid injection pressure, injection angle and heat treatment holding temperature, the thickness, surface quality and internal structure of the thin strip can be effectively controlled, thereby ensuring the stability and consistency of material properties. By optimizing the process parameters, the yield rate exceeds 95%, which reduces production costs and is conducive to large-scale industrial production.

[0032] 3. Broad application prospects: With its excellent comprehensive performance, the soft magnetic material of the present invention can be widely used in new energy vehicle motors, 5G communication base station radio frequency devices, aerospace power systems, high-efficiency transformers and other fields, promoting the technological upgrading of related industries and bringing significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 The cast medium entropy FeCoNi-based soft magnetic alloy prepared in Example 1 of the present invention and the cast Fe 33.34 Co 33.33 Ni 33.33 Metallographic diagram, where (a) is cast Fe 33.34 Co 33.33 Ni 33.33 Metallographic diagram, (b) is cast Fe 32.61 Co 32.6 1Ni 32.61 Ti1Al1Nb 0.17 Metallographic diagram.

[0035] Figure 2 It is a schematic diagram of vacuum belt spinning in the method for preparing the cast medium entropy FeCoNi-based soft magnetic alloy of the present invention.

[0036] Figure 3 This is a physical picture of the medium-entropy FeCoNi-based alloy strip prepared by vacuum spinning in Example 1 of the present invention.

[0037] Figure 4 It is a schematic diagram of an equivalent circuit analytical model for impedance testing of the present invention.

[0038] Figure 5 This is the XRD diffraction pattern of the entropy FeCoNi-based soft magnetic alloy in Example 1 of the present invention.

[0039] Figure 6 1 is the hysteresis loop diagram of the entropy FeCoNi-based soft magnetic alloy in Example 1 and Example 2 of the present invention.

[0040] Figure 7 1 and 2 are TAFEL curves of the FeCoNi-based soft magnetic alloys in Examples 1 and 2 of the present invention.

[0041] Figure 8 1 is the Nyquist diagram of the entropy FeCoNi-based soft magnetic alloy in Example 1 and Example 2 of the present invention.

[0042] Figure 9 This is a metallographic diagram of the cast medium-entropy FeCoNi-based soft magnetic alloy prepared in Example 3 of the present invention.

[0043] Figure 10 This is the XRD diffraction pattern of the medium-entropy FeCoNi-based soft magnetic alloy prepared in Example 3 of the present invention.

[0044] Figure 11 1 is a hysteresis loop diagram of Example 3 of the present invention, wherein (a) is a hysteresis loop diagram of Example 3, and (b) is a partial enlarged diagram of the hysteresis loop.

[0045] Figure 12 These are TAFEL curves of the medium-entropy FeCoNi-based alloy after different treatments in Example 3 of the present invention.

[0046] Figure 13 3 is the Nyquist diagram of the medium-entropy FeCoNi-based alloy of Example 3 of the present invention.

[0047] Figure 14 1 is a hysteresis loop diagram of the medium-entropy FeCoNi-based alloy strip after heat treatment in Comparative Example 1 of the present invention.

[0048] Figure 15 It is a hysteresis loop diagram of the medium-entropy FeCoNi-based alloy strip after heat treatment in Comparative Example 2 of the present invention.

[0049] Figure 163 is a hysteresis loop diagram of the medium-entropy FeCoNi-based alloy strip after heat treatment in Comparative Example 3 of the present invention.

[0050] Figure 17 This is a physical picture of the medium-entropy FeCoNi-based alloy strip prepared by vacuum belting in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0051] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1

[0053] Composition: Calculated by atomic ratio, the raw materials are Fe 32.61%, Co 32.61%, Ni 32.61%, Al 1%, Ti 1%, Nb 0.17%, and the balance is inevitable impurities.

[0054] The preparation process includes the following steps:

[0055] (1) Raw material pretreatment: Select 99.8% pure electrolytic iron, 99.8% pure electrolytic cobalt, 99.8% pure electrolytic nickel, 99.9% pure aluminum, 99.8% pure titanium, and 99.8% pure niobium, weigh them, place them in a mixer, mix them at 100 r / min for 60 min, and then place them in a vacuum drying oven at 80 °C for 2 h.

[0056] (2) Alloy smelting: Place the dried raw materials into a vacuum arc melting furnace and evacuate to 1×10 -3 Pa, introduce 10L / min high-purity argon, set the power to 10 kW to melt the raw materials, repeat the smelting 6 times, each time for 4 minutes, and let it stand for 1.5 minutes after melting.

[0057] (3) Strip forming: A single-roller strip forming machine was used. The copper roller had a diameter of 350 mm, a surface roughness of Ra = 0.6 μm, a rotation speed of 12 m / s, and a roller surface temperature controlled at 40 °C. The smelted alloy liquid was sprayed onto the surface of the copper roller through a circular hole nozzle with a diameter of 4 mm at a pressure of 0.3 MPa. The spraying angle was 60°, and a thin strip with a thickness of about 40 μm was obtained.

[0058] (4) Post-processing of the strip: Immerse the strip in a dilute hydrochloric acid solution with a mass concentration of 8% for pickling for 4 min, rinse with deionized water until neutral, dry in a vacuum drying oven at 65 °C for 2.5 h, and finally cut with precision cutting equipment.

[0059] (5) Heat treatment: Place the slit metal strip into a crucible. Push the crucible into the tube furnace, install the furnace plug and sealing flange, open the argon bottle, and exhaust the gas in the furnace chamber. Then set the heat treatment parameters: initial temperature 50℃, heating to 800℃, heating rate 10℃ / min, heating time 75min, holding temperature for 2 hours, and then cooling to 50℃.

[0060] (6) Post-treatment: Immerse the tape in a dilute hydrochloric acid solution with a mass concentration of 8% for pickling for 4 min, rinse with deionized water until neutral, dry in a vacuum drying oven at 65 °C for 2.5 h, and finally vacuum package.

[0061] The performance test of the medium entropy FeCoNi-based alloy obtained in Example 1 was carried out, and the results are as follows:

[0062] In terms of magnetic properties, the saturation magnetization Ms of the ingot obtained by vacuum melting is 292.86 emu / g, and the coercive force Hc is 5.33 Oe. The saturation magnetization Ms of the strip obtained by stripping is 332.26 emu / g, and the coercive force Hc is 6.46 Oe. The saturation magnetization Ms of the strip after heat treatment is 353.33 emu / g, and the coercive force Hc is 5.55 Oe. The coercive force is slightly reduced, the saturation magnetization is increased, and the comprehensive magnetic properties are improved. In terms of corrosion performance, the corrosion potential of the ingot obtained by vacuum melting is -361 mV, and the corrosion current density is 3.412×10 -6 A / cm 2 The corrosion potential of the strip obtained by strip spinning is -296 mV, and the corrosion current density is 2.577×10 -6 A / cm 2 The corrosion resistance of the heat-treated strip is improved. The corrosion potential of the heat-treated strip is -252mV, and the corrosion current density is 3.287×10 -6 A / cm 2 The corrosion potential is highly positive and the corrosion tendency is small; the comprehensive corrosion performance is slightly lower than that of the unheat-treated strip, but the comprehensive corrosion performance is still better than that of the cast material.

[0063] Example 2

[0064] The raw material formula and the overall preparation method of Example 2 are the same as those of Example 1, except that the heat treatment temperature of Example 2 is 900° C., the heating time is 85 min, and the heat preservation time is 2 hours.

[0065] The performance test of the medium entropy FeCoNi-based alloy obtained in Example 2 was carried out, and the results were as follows:

[0066] In terms of magnetic properties, the saturation magnetization Ms of the heat-treated strip is 338.64 emu / g, and the coercivity Hc is 4.37 Oe. The coercivity is significantly reduced, the saturation magnetization is increased, and the overall magnetic properties are improved. In terms of corrosion performance, the corrosion potential of the heat-treated strip is -250 mV, and the corrosion current density is 3.294×10 -6 A / cm 2 The corrosion potential is highly positive, the corrosion tendency is small, and the comprehensive corrosion performance is slightly lower than that of the unheat-treated strip, but the comprehensive corrosion performance is still better than that of the cast material.

[0067] Example 3

[0068] The preparation method of Example 3 is the same as that of Example 1, except for the content of metal elements in the raw materials.

[0069] Composition: Calculated by atomic ratio, the raw materials are Fe 31.89%, Co 31.89%, Ni 31.89%, Al 2%, Ti 2%, Nb 0.33%, and the balance is inevitable impurities.

[0070] The performance test of the medium entropy FeCoNi-based alloy obtained in Example 3 was carried out, and the results are as follows:

[0071] In terms of magnetic properties, the saturation magnetization Ms of the ingot obtained by vacuum melting is 291.07 emu / g, and the coercive force Hc is 4.77 Oe. The saturation magnetization Ms of the strip obtained by stripping is 281.72 emu / g, and the coercive force Hc is 5.83 Oe. The saturation magnetization Ms of the strip after heat treatment is 353.64 emu / g, and the coercive force Hc is 6.43 Oe. The coercive force is improved, the saturation magnetization is significantly improved, and the comprehensive magnetic properties are improved. In terms of corrosion performance, the corrosion potential of the ingot obtained by vacuum melting is -283 mV, and the corrosion current density is 3.733×10 -6 A / cm 2 The corrosion potential of the strip obtained by strip spinning is -297 mV, and the corrosion current density is 3.404×10 -6 A / cm 2 The corrosion performance of the heat-treated strip is improved. The corrosion potential of the heat-treated strip is -228mV, and the corrosion current density is 2.583×10 -6 A / cm 2 The corrosion potential is highly positive and the corrosion tendency is small; the corrosion current density is small, the corrosion rate is slow, and the comprehensive corrosion performance is excellent.

[0072] The corrosion parameters of the medium-entropy FeCoNi-based alloy obtained in the above examples are shown in Table 1, and the magnetic performance parameters are shown in Table 2.

[0073] Table 1 Corrosion parameters of different materials under different treatment methods

[0074]

[0075] Table 2 Magnetic properties of different materials under different treatment methods

[0076]

[0077] Comparative Example 1

[0078] The preparation method is the same as that of Example 1, except for the type of metal elements in the raw materials.

[0079] Composition: Calculated by atomic ratio, the raw materials are Fe 30%, Co 30%, Ni 30%, Al 7%, Ta 3%, and the balance is inevitable impurities.

[0080] The performance test of the medium entropy FeCoNi-based alloy obtained in Comparative Example 1 was carried out, and the results are as follows:

[0081] The saturation magnetization Ms of the heat-treated strip is 227.34 emu / g, and the coercive force Hc is 5.69 Oe. Compared with Example 1, the coercive force is similar, but the saturation magnetization is much lower than that of Example 1. It can be seen that the magnet prepared by the method of the present invention can obtain a higher saturation magnetization and better overall magnetic properties.

[0082] Comparative Example 2

[0083] The preparation method is the same as that of Example 1, except for the type of metal elements in the raw materials.

[0084] Composition: Calculated by atomic ratio, the raw materials are Fe 29.33%, Co 29.33%, Ni 29.33%, Al 7%, Ta 5%, and the balance is inevitable impurities.

[0085] The performance test of the medium entropy FeCoNi-based alloy obtained in Comparative Example 2 was carried out, and the results are as follows:

[0086] The saturation magnetization Ms of the heat-treated strip is 203.48 emu / g, and the coercivity Hc is 12.41 Oe. The coercivity exceeds the range of soft magnetic materials, and the saturation magnetization is much lower than that of Example 1. It can be seen that the magnet prepared by the preparation method of the present invention can obtain a higher saturation magnetization and better overall magnetic properties.

[0087] Comparative Example 3

[0088] The preparation method is the same as that of Example 1, except for the type of metal elements in the raw materials.

[0089] Composition: Calculated by atomic ratio, the raw materials are Fe 28.66%, Co 28.66%, Ni 28.66%, Al 7%, Ta 7%, and the balance is inevitable impurities.

[0090] The performance test of the medium entropy FeCoNi-based alloy obtained in Comparative Example 3 was carried out, and the results are as follows:

[0091] The saturation magnetization Ms of the heat-treated strip is 163.41 emu / g, and the coercivity Hc is 18.73 Oe. The coercivity exceeds the range of soft magnetic materials, and the saturation magnetization is much lower than that of Example 1. It can be seen that the magnet prepared by the preparation method of the present invention can obtain a higher saturation magnetization and better overall magnetic properties.

[0092] Comparative Example 4

[0093] The raw material formula and overall preparation method of Comparative Example 4 are the same as those of Example 1, except that the copper roller speed of the vacuum belt in Comparative Example 4 is 40 m / s. Figure 17 As shown, it shows that the rotation speed of the copper roller is too high, resulting in the sample being finely divided into particles and needles, which has no practical application value.

[0094] Figure 1 The cast medium entropy FeCoNi-based soft magnetic alloy prepared in Example 1 of the present invention and the cast Fe 33.34 Co 33.33 Ni 33.33 Metallographic diagram, where (a) is cast Fe 33.34 Co 33.33 Ni 33.33 The metallographic diagram is obtained by vacuum melting process; (b) is the cast Fe prepared in Example 1 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 Metallographic diagram. Figure 1 (a) It can be seen that cast Fe 33.34 Co 33.33 Ni 33.33 The grains are equiaxed, coarse, and have an average size of about 300 μm. Figure 1 (b) It can be seen that cast Fe 32.6 1Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The grains are also equiaxed, but the average grain size is only 40 μm. It can be seen that the material prepared using the raw material formula of the present invention has a smaller grain size and a better microstructure.

[0095] Figure 2This is a schematic diagram of the vacuum stripping process used in the present invention's method for preparing a medium-entropy FeCoNi-based soft magnetic alloy as-cast. The diagram shows that in a vacuum or inert gas environment, the metal feedstock is heated above its melting point to form a uniform melt. The molten metal is then passed through a quartz nozzle, driven by high-pressure gas or gravity to form a thin stream. The molten stream is then ejected onto the surface of a high-speed rotating copper roller, where it is instantaneously cooled (contact time <1 ms), forming a thin ribbon with a thickness of 20-50 μm.

[0096] Figure 3 This is a photo of a medium-entropy FeCoNi-based alloy strip produced by vacuum spinning in Example 1 of the present invention. The alloy strip exhibits a continuous ribbon structure, 2 mm in width, and a uniform thickness generally ranging from 20 to 50 μm. The surface exhibits a metallic luster, while the free surface (the side exposed to air) is relatively rough.

[0097] Figure 4 This is a schematic diagram of the equivalent circuit analytical model for the impedance test of the present invention. The equivalent circuit is designed based on the specific electrochemical behavior and interface characteristics of the material, and is then fitted to minimize errors.

[0098] Figure 5 This is the XRD diffraction pattern of the entropy FeCoNi-based soft magnetic alloy in Example 1 of the present invention. It includes the spectrum of the XRD test of the sample after vacuum melting and the spectrum of the XRD test of the sample after vacuum stripping. 32.6 1Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The characteristic diffraction peaks are highly consistent with the standard database PDF47-1417 card, confirming that the material presents a single face-centered cubic (FCC) solid solution feature. This structure has low resistance to magnetic domain wall movement and has the performance advantages of low coercivity, high magnetic permeability, and high saturation magnetization. The diffraction intensity of the material in the (111) and (200) crystal plane directions is large, indicating that the directionality of the crystal orientation arrangement is improved and the degree of atomic ordering is increased, reflecting that the integrity of the material lattice has been further optimized. For the Fe prepared by vacuum belting 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The material is still composed of a single face-centered cubic (FCC) solid solution phase. After stripping, the diffraction peak intensity of the (111) crystal plane increases. The (111) plane is the easy magnetization direction of the FCC structure. Increasing the orientation can optimize the high-frequency magnetic permeability, but may slightly increase the coercivity.

[0099] Figure 6The hysteresis loop diagram of the entropy FeCoNi-based soft magnetic alloy in Example 1 and Example 2 of the present invention. The raw material formula and vacuum belt spinning technical parameters of Example 2 are the same as those of Example 1, except that the heat treatment temperature of Example 2 is 900 °C. Figure 6 (a) is the hysteresis loop diagram of Example 1 and Example 2, which is used to analyze the saturation magnetization intensity of the material. The maximum value of the hysteresis loop corresponds to the saturation magnetization intensity of the material. Figure 6 (b) is a partial enlarged view of the hysteresis loop, which is used to analyze the coercive force of the material. The narrower the hysteresis loop, the smaller the coercive force. Figure 6 The different curves correspond to different preparation methods, including the hysteresis loop of the sample obtained by vacuum melting, the hysteresis loop of the sample obtained by vacuum stripping, the hysteresis loop of Example 1 corresponding to the heat treatment at 800 °C, and the hysteresis loop of Example 2 corresponding to the heat treatment at 900 °C. The corresponding material for vacuum melting is the cast Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 As can be seen from the figure, the saturation magnetization Ms is 292.86 emu / g and the coercive force Hc is 5.33 Oe. The corresponding material of vacuum belting is Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 As can be seen from the figure, the saturation magnetization Ms is 332.26 emu / g and the coercive force Hc is 6.46 Oe.

[0100] The corresponding material for 800 ℃ heat treatment is Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The strip corresponds to the hysteresis loop of Example 1. As can be seen from the figure, the saturation magnetization Ms is 353.33 emu / g and the coercive force Hc is 5.55 Oe. Compared with the unheat-treated strip, the maximum value of the curve of this material is larger, indicating that the saturation magnetization is larger; the hysteresis loop is narrower, indicating that the coercive force is smaller, but still higher than that of the cast alloy. The corresponding material for the 900 ℃ heat treatment is Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17The strip has the same material composition as Example 1 and corresponds to the hysteresis loop of Example 2. As shown in the figure, the saturation magnetization Ms is 338.64 emu / g and the coercivity Hc is 4.37 Oe. Compared with the unheat-treated strip, the maximum value of the curve is larger, indicating a higher saturation magnetization; the hysteresis loop is narrower, indicating a lower coercivity.

[0101] Figure 7 is the TAFEL curve of the FeCoNi-based soft magnetic alloy in Example 1 and Example 2 of the present invention. 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The preparation process is vacuum melting, Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The preparation process is vacuum belt spinning, Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The preparation process (800 ℃) is to keep the temperature at 800 ℃ for two hours after vacuum belting, which corresponds to the hysteresis loop of Example 1. 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The (900°C) preparation process involves vacuum stripping followed by a two-hour hold at 900°C, corresponding to the hysteresis loop of Example 2. Compared to the vacuum-melted cast alloy, the curves of Examples 1 and 2 exhibit larger maximum values, indicating higher saturation magnetization and better magnetic properties. Therefore, magnets prepared using the present invention exhibit larger maximum values ​​in their hysteresis loops, resulting in higher saturation magnetization, essentially unchanged coercivity, and improved overall magnetic properties.

[0102] Figure 8 The Nyquist diagram of the entropy FeCoNi-based soft magnetic alloy in Example 1 and Example 2 of the present invention. The corresponding material of vacuum melting is the cast Fe prepared by vacuum melting. 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The corresponding material of vacuum belt is Fe 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb 0.17 The corresponding material for 800 ℃ heat treatment is Fe strip which is vacuum stripped and kept at 800 ℃ for two hours. 32.61 Co 32.61 Ni 32.61 Ti1Al1Nb0.17 The strip material corresponds to the hysteresis loop of Example 1. The corresponding material for the 900°C heat treatment is the Fe 32.61 Co 32.61 Ni 32.6 1Ti1Al1Nb 0.17 The strip, with the same material composition as Example 1, corresponds to the hysteresis loop of Example 2. The increase in arc radius indicates increased resistance to electron migration, reflecting the material's superior corrosion resistance. The material prepared by vacuum melting has the smallest arc radius and the weakest corrosion resistance. The increased arc radius of the materials in Examples 1 and 2 indicates improved corrosion resistance compared to the cast alloy.

[0103] Figure 9 The metallographic diagram of the cast medium entropy FeCoNi-based soft magnetic alloy prepared in Example 3 of the present invention is shown in FIG. 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 Metallographic diagram. Figure 1 Compared to (b), the grains remain equiaxed. The increased proportions of Ti, Al, and Nb provide more nucleation cores, further reducing the grain size to an average of approximately 20 μm. The material contains only one (Fe, Ni) phase, exhibiting a single face-centered cubic (FCC) solid solution.

[0104] Figure 10 This is the XRD diffraction pattern of the medium entropy FeCoNi-based soft magnetic alloy prepared in Example 3 of the present invention. It includes the spectrum of the XRD test of the sample after vacuum melting and the spectrum of the XRD test of the sample after vacuum stripping. 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The characteristic diffraction peaks are highly consistent with the standard database PDF47-1417 card, confirming that the material presents a single face-centered cubic (FCC) solid solution feature. This structure has low resistance to magnetic domain wall movement and has the performance advantages of low coercivity, high magnetic permeability, and high saturation magnetization. The diffraction intensity of the material in the (111) and (200) crystal plane directions is large, indicating that the directionality of the crystal orientation arrangement is improved and the degree of atomic ordering is increased, reflecting that the integrity of the material lattice has been further optimized. For the Fe prepared by vacuum belting 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33The material is still composed of a single face-centered cubic structure (FCC) solid solution phase. Compared with the cast state, the diffraction intensity of the material in the (111) crystal plane direction is reduced, indicating that the orientation of the crystal orientation is improved and the degree of atomic ordering is reduced, and the magnetic properties are reduced. Figure 16 The analysis results corroborate each other.

[0105] Figure 11 3 is a hysteresis loop diagram of the medium-entropy FeCoNi-based soft magnetic alloy prepared in Example 3 of the present invention. Figure 11 (a) is the hysteresis loop diagram of Example 3, which is used to analyze the saturation magnetization intensity of the material. The maximum value of the hysteresis loop corresponds to the saturation magnetization intensity of the material. Figure 11 (b) is a partial enlarged view of the hysteresis loop, which is used to analyze the coercive force of the material. The narrower the hysteresis loop, the smaller the coercive force. Figure 11 The different curves correspond to different preparation methods, including the hysteresis loop of the sample obtained by vacuum melting, the hysteresis loop of the sample obtained by vacuum stripping, and the hysteresis loop of Example 3 corresponding to the 800 °C heat treatment. The corresponding material for vacuum melting is the cast Fe 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 As can be seen from the figure, the saturation magnetization Ms is 291.07 emu / g and the coercive force Hc is 4.77 Oe. The corresponding material of vacuum belting is Fe 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 Strip. As shown in the figure, the saturation magnetization, Ms, is 281.72 emu / g, and the coercive force, Hc, is 5.83 Oe. Compared to the as-cast alloy, the curve has a smaller maximum, indicating a lower saturation magnetization; the hysteresis loop is wider, indicating a higher coercive force.

[0106] The corresponding material for 800 ℃ heat treatment is Fe 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The strip corresponds to the hysteresis loop of Example 3. As shown in the figure, the saturation magnetization Ms is 353.64 emu / g, and the coercivity Hc is 6.43 Oe. Compared with the as-cast alloy and strip, the maximum value of this curve is significantly larger, indicating a significant increase in saturation magnetization; the wider hysteresis loop indicates a greater coercivity, and overall, the magnetic properties have been improved.

[0107] Figure 12 The TAFEL curves of the medium entropy FeCoNi-based alloy after different treatment methods in Example 3 of the present invention are shown in FIG.31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The preparation process is vacuum melting, Fe 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The preparation process is vacuum belt spinning, Fe 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The preparation process (800°C) involves vacuum stripping followed by two hours of holding at 800°C. Compared to the vacuum-melted cast alloy, the curve for Example 3 exhibits a larger maximum value, indicating a higher saturation magnetization. However, the hysteresis loop is wider, and the coercivity increases (higher coercivity indicates poorer soft magnetic properties). Overall, the magnetic properties are improved. Compared to Example 1, the saturation magnetizations are similar, but Example 3 exhibits a higher coercivity. While Example 1 exhibits better magnetic properties, the difference is not significant. However, Example 3 exhibits a higher proportion of alloying elements, resulting in improved corrosion resistance.

[0108] Figure 13 This is the Nyquist diagram of Example 3 of the present invention. The corresponding material for vacuum melting is the cast Fe prepared by vacuum melting. 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The corresponding material of vacuum belt is Fe 31.89 Co 31.89 Ni 31.8 9Ti2Al2Nb 0.33 The corresponding material for 800 ℃ heat treatment is Fe strip which is vacuum stripped and kept at 800 ℃ for two hours. 31.89 Co 31.89 Ni 31.89 Ti2Al2Nb 0.33 The strip material corresponds to the test results of Example 3. The increase in arc radius indicates increased resistance to electron migration, reflecting the material's superior corrosion resistance. The material prepared by vacuum melting has the smallest arc radius and the weakest corrosion resistance. The increased arc radius of the material in Example 3 indicates improved corrosion resistance compared to the cast alloy.

[0109] Figure 14 This is the hysteresis loop of the medium entropy FeCoNi-based alloy strip after heat treatment in comparative example 1 of the present invention. 30 Co 30 Ni 30Al7Ta3 strip. As shown in the figure, the saturation magnetization Ms is 227.34 emu / g, and the coercivity Hc is 5.69 Oe. Compared with Example 1, the maximum value of this curve is smaller, indicating lower saturation magnetization and poorer magnetic properties. This shows that magnets prepared using the present invention can achieve higher saturation magnetization and better overall magnetic properties.

[0110] Figure 15 This is the hysteresis loop diagram of the medium entropy FeCoNi-based alloy strip after heat treatment in comparative example 2 of the present invention. The material is Fe 29.33 Co 29.33 Ni 29.33 Al7Ta5 strip. As shown in the figure, the saturation magnetization Ms is 203.48 emu / g, and the coercivity Hc is 12.41 Oe. While the coercivity exceeds the range for soft magnetic materials, the saturation magnetization is much lower than that of Example 1. This indicates that the magnet prepared using the present invention can achieve a higher saturation magnetization and better overall magnetic properties.

[0111] Figure 16 This is the hysteresis loop of the medium entropy FeCoNi-based alloy strip after heat treatment in comparative example 3 of the present invention. The material is Fe 28.66 Co 28.66 Ni 28.66 Al7Ta7 strip. As shown in the figure, the saturation magnetization Ms is 163.41 emu / g, and the coercivity Hc is 18.73 Oe. While the coercivity exceeds the range for soft magnetic materials, the saturation magnetization is much lower than that of Example 1. This indicates that the magnet prepared using the present invention can achieve a higher saturation magnetization and better overall magnetic properties.

[0112] Figure 17 This is a physical picture of the medium-entropy FeCoNi-based alloy strip prepared by vacuum belting in Comparative Example 4 of the present invention. The sample is finely divided into particles and needles and has no practical application value.

[0113] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A new medium entropy FeCoNi-based soft magnetic material, characterized in that: Calculated by atomic ratio, its chemical composition is: iron (Fe) 25-35%, cobalt (Co) 25-35%, nickel (Ni) 25-35%, aluminum (Al) 1-5%, titanium (Ti) 1-5%, niobium (Nb) 0.1-2%, and the remainder is unavoidable impurities.

2. The novel medium-entropy FeCoNi-based soft magnetic material according to claim 1, characterized in that The material has a saturation magnetization Ms of ≥270 emu / g; an initial magnetic permeability μi of ≥6000; and a magnetic loss of ≤320 W / kg under conditions of 100 kHz and 1 T.

3. The novel medium-entropy FeCoNi-based soft magnetic material according to claim 1, characterized in that The corrosion potential of the material in 3.5% mass fraction NaCl solution is Ecorr≥-300 mV, and the corrosion current density is Icorr≤3.5×10 -6 A / cm 2 .

4. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Raw material pretreatment: Select electrolytic iron, electrolytic cobalt, electrolytic nickel metal raw materials with a purity of ≥99.5%, as well as pure aluminum, pure titanium, and pure niobium as additive raw materials, mix the weighed raw materials, and then dry them; S2. Alloy melting: Place the dried raw materials into a vacuum arc melting furnace, evacuate the furnace, and introduce high-purity argon as a protective gas for vacuum melting; S3, strip forming: a single-roll strip forming machine is used for the forming operation. The smelted alloy liquid is sprayed onto the surface of the high-speed rotating copper roller of the single-roll strip forming machine. The alloy liquid is rapidly cooled and solidified on the surface of the copper roller to form a metal strip. S4, strip forming post-processing: the metal strip is pickled, washed and dried in sequence, and cut into appropriate sizes; S5. Heat treatment: The slit metal strip is placed in a tube furnace for heat treatment, and the strip is taken out after cooling; S6. Post-processing: sequentially pickling, water washing and vacuum drying the heat-treated thin strip to obtain the novel medium-entropy FeCoNi-based soft magnetic material.

5. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S1, mixing is performed in a mixer at a rotation speed of 100 r / min for 60 minutes; and drying is performed in a vacuum drying oven at a temperature of 70-100° C. for 1.5-3 hours.

6. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S2, the dried raw materials are placed in a vacuum arc melting furnace and the pressure in the furnace is pumped down to 1×10 -3 Below Pa, the flow rate of high-purity argon is 8-12 L / min.

7. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S2, the power of the vacuum arc melting is 8-12 kW, the number of melting times is 6-8 times, and the time of each melting is 3-5 minutes.

8. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S3, the diameter of the copper roller of the single-roller belt spinning machine is 300-400 mm, and the surface roughness Ra is ≤ 0.8 μm; the rotation speed of the copper roller is 10-30 m / s, and the roller surface temperature is 20-80°C.

9. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S3, the molten alloy liquid in the quartz tube is sprayed onto the surface of the high-speed rotating copper roller through a circular nozzle using high-pressure argon gas of 0.8-1.2 MPa. The nozzle diameter is 2-4 mm, the distance from the copper roller surface is 1-3 mm, the injection pressure of the alloy liquid is 0.1-0.5 MPa, and the injection angle is 30-60°. The cooling rate of the alloy liquid on the copper roller surface is 10 5 -10 6 ℃ / s, the thickness of the ribbon is 20-50 μm.

10. The method for preparing the novel medium-entropy FeCoNi-based soft magnetic material according to claim 4, characterized in that: In step S5, the initial temperature of the heat treatment is 50°C, the material is heat treated at 700-900°C, the heating rate is 5-15°C / min, and the holding time is 1-3 hours.

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