High-temperature-resistant soft-magnetic high-entropy alloy fiber and preparation method thereof

Abstract

The invention relates to a high-temperature-resistant soft-magnetic high-entropy alloy fiber and a preparation method thereof. The preparation method comprises the following steps: weighing elemental metal raw materials according to a specific proportion of a chemical formula FeaCobNicAldTaeSifCg, uniformly mixing the elemental metal raw materials, smelting the elemental metal raw materials for multiple times through a high-vacuum arc smelting furnace, and carrying out suction casting to obtain a master alloy bar; and heating the mother alloy rod to 1450-1650 DEG C in a protective gas environment through a coil for melting, then preparing the high-entropy alloy fiber by utilizing a spraying process and cooling water cooling, and finally obtaining the high-temperature-resistant soft-magnetic high-entropy alloy fiber through annealing treatment. The alloy fiber provided by the invention has excellent soft magnetic properties including high saturation magnetization intensity and low coercive force, and also has high-temperature stability and good ductility, so that the problems of unstable soft magnetic properties, insufficient high-temperature strength, poor ductility and many processing defects of alloy fibers in the prior art are improved, and the alloy fiber has good application prospects. The fiber is smooth in surface, uniform in size, highly optimized in mechanical property and magnetic property, and suitable for high-performance application in magnetic sensors, high-end electronic equipment and extreme environments.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy fiber preparation, and in particular to a high-temperature resistant soft magnetic high-entropy alloy fiber and a preparation method thereof. Background Art

[0002] Soft magnetic fibers, such as amorphous and polycrystalline fibers based on cobalt (Co) and iron (Fe), are widely used in sensors, actuators, and electromagnetic shielding devices due to their low coercivity (Hc) characteristics. In recent years, the potential applications of cobalt alloys and cobalt / iron-based soft magnetic fibers in geomagnetic navigation, human-computer interaction, and human-like tactile sensing have attracted widespread attention. However, due to their poor elongation, the large-scale production and application of soft magnetic fibers and related devices still face many challenges.

[0003] As a newly developed soft magnetic fiber, high entropy alloy fiber provides a new direction for overcoming the mechanical performance problems of soft magnetic fibers with its excellent mechanical properties. However, after annealing, it is difficult to avoid the annealing brittleness problem of high entropy alloy fibers, which makes it difficult to take into account both mechanical properties and soft magnetic properties. In addition, the main materials for industrial components used in high-temperature environments are currently high-temperature alloys, but the performance improvement of traditional high-temperature alloys has encountered bottlenecks. Its service temperature is affected by the stability of the alloy structure, and traditional high-temperature alloys usually have a more complex phase structure, which increases the possibility of precipitation of harmful phases at high temperatures. In the case of widespread use of fiber materials with higher environmental requirements, how to avoid the annealing brittleness of high entropy alloy fibers and improve their high-temperature performance has become a huge challenge facing the industry.

[0004] At present, the main methods for preparing high-entropy alloy fibers in China are melt drawing, glass coating and inner circle water spinning. However, no matter which preparation method is used, the consistency of the material (such as the diameter change rate at different positions) and its performance will be limited by the stability of the equipment and process. For example, melt drawing and drawing are the main methods for preparing high-entropy alloy fibers at this stage. The drawing method achieves fiber consistency through die extrusion, but the process is complicated and it is difficult to prepare high-entropy alloy fibers with a diameter of less than 500 μm, and it is difficult to meet the needs of large-scale production. The melt drawing method uses a high-speed copper roller to cut the melt to prepare the fiber, which is highly efficient, but the surface of the prepared fiber is irregular and often has large pits. This surface defect easily leads to stress concentration, and the fiber is difficult to use for structural materials, limiting its application range.

[0005] For example, the Chinese invention patent application with application number CN202110896192.9 discloses a method for preparing high entropy alloy fibers, which prepares high entropy alloy fibers by melt drawing method, and performs surface treatment on the fibers to form a porous structure. However, the fibers prepared by this method have many surface defects, which easily lead to stress concentration, limiting the application of fibers in structural materials; another invention patent application with application number CN202410048078.4 discloses a method for preparing medium / high entropy alloy fibers with excellent tensile properties, which comprises: preparing fibers by heat treating a master alloy rod at 1200°C and then drawing the fibers through a multi-pass die at 800°C. Compared with the melt drawing method, the fibers prepared by this method have a more uniform surface and excellent performance, but the preparation process is complicated, and it is difficult to produce fibers with a diameter of less than 500 μm and a high aspect ratio, which cannot meet the needs of industrial production.

[0006] In addition, high entropy alloy fibers are prone to precipitating harmful phases in high-temperature service environments, which reduces their organizational stability and affects the long-term stability of mechanical and magnetic properties. At the same time, high entropy alloy fiber materials prepared in the prior art often show annealing brittleness after annealing, resulting in reduced fiber elongation and deterioration of mechanical properties, further limiting their use under extreme conditions.

[0007] With the widespread application of new sensors and fiber structural materials, higher requirements are placed on the comprehensive performance of alloy fibers, such as better soft magnetic properties, higher elongation, excellent high temperature stability and surface quality. How to overcome the shortcomings of existing technologies and prepare high-entropy alloy fibers with good surface quality, high elongation, high magnetic properties and that can meet industrial-scale production is the focus and difficulty of research in related fields. Summary of the invention

[0008] One of the technical problems to be solved by the present invention is to provide a method for preparing high-temperature resistant soft magnetic high-entropy alloy fibers, so as to solve the problems of unstable fiber performance, complex preparation process and difficulty in balancing mechanical properties and soft magnetic properties existing in the preparation methods of conventional alloy fibers in the prior art.

[0009] In order to overcome the above defects of the prior art, the present invention provides a method for preparing high temperature resistant soft magnetic high entropy alloy fiber, comprising the following steps: S1: Using atomic percentage Fe a Co b Ni c Al d Ta e Si f C gWeigh a single metal raw material according to the chemical formula of , wherein a> 25, b> 25, c> 25, 0≤d≤20, 0≤e≤20, 0≤f≤20, 0≤g≤20, and a+b+c+d+e+f+g= 100, and mix them uniformly to obtain a mixed metal raw material; S2: melting the mixed metal raw material obtained in step S1 in a high vacuum arc melting furnace to obtain a button-shaped master alloy, and then obtaining a master alloy rod by suction casting; S3: putting the master alloy rod obtained in the step S2 into a container, and introducing a protective gas into the container, then heating the master alloy rod to 1450-1650° C. by coil heating, and obtaining a molten liquid after the master alloy rod is melted. The molten liquid is ejected from the ejection port of the container under the action of the protective gas pressure, and cooled by cooling water to obtain a high entropy alloy fiber, which is then further annealed to obtain a high temperature resistant soft magnetic high entropy alloy fiber.

[0010] Compared with the prior art, the preparation method of the high temperature resistant soft magnetic high entropy alloy fiber of the present invention has the following advantages: Taking both mechanical and magnetic properties into account: The present invention adopts a specific proportion of Fe, Co, and Ni as the main components, supplemented by Al, Ta, Si, C and other strengthening elements as raw materials, and effectively enhances the soft magnetic properties and high-temperature stability of the material through high entropy design. Through the specific chemical composition ratio, the saturation magnetization and coercive force of the fiber are properly controlled, and it has excellent soft magnetic properties. By designing a heating temperature of 1450-1650°C and an annealing process, the phase separation or uneven organization of the material caused by high-temperature treatment is avoided, the mechanical properties of the material are improved, and finally the dual optimization of soft magnetic and mechanical properties is achieved; High efficiency and simplicity of preparation method: The present invention combines high vacuum arc melting, suction casting and jet cooling processes, avoiding the complex mold limitation of the drawing method in the prior art. At the same time, the fiber surface prepared by the jet process is smoother, avoiding the fiber surface defect problem caused by the traditional melt drawing method. In the jet cooling process, the design of coil heating and protective gas pressure ensures the uniform spraying of the molten liquid, further improving the morphology and performance consistency of the fiber. The preparation effect of the high entropy alloy fiber prepared by the preparation method of the present invention is remarkable. In the prior art, annealing treatment often introduces material brittleness and reduces the tensile properties of the fiber. The present invention ensures the stability of the FCC phase structure of the high entropy alloy fiber by combining the process of spraying molten liquid with rapid water quenching, while maintaining excellent mechanical and magnetic properties, thereby solving the brittleness problem of the prior art. Through the innovation of material design and preparation process, the problems of complex preparation, unstable mechanical properties and soft magnetic properties, and annealing brittleness of the existing high entropy alloy fiber are successfully solved. The prepared high-temperature resistant soft magnetic high entropy alloy fiber not only has excellent high-temperature stability, mechanical properties and soft magnetic properties, but also can meet the needs of industrial production, and has broad application prospects in magnetic sensors and other high-end fields.

[0011] In a possible embodiment, in step S1, the Fe a Co b Ni c Al d Ta e Si f C g The chemical formula is Fe 34 Co 29 Ni 29 Al3Ta2Si2C1.

[0012] Compared with the existing technology, the above technical scheme ensures the soft magnetic properties of the material by further refining the composition of the raw materials and using specific proportions of Fe (34%), Co (29%) and Ni (29%) as the main components. These three elements are mainly solid solution strengthened and can maintain a stable FCC phase structure at high temperatures, while improving the saturation magnetization and low coercive force of the fiber; while Al, Ta, Si and C are added in trace amounts, mainly by forming a metastable phase or increasing grain boundary energy to improve the high-temperature oxidation resistance, fatigue resistance and ductility of the fiber. In particular, trace amounts of Ta and C contribute significantly to grain refinement and thermal stability, thereby inhibiting the embrittlement phenomenon caused by high-temperature precipitation phases. Through the high-entropy synergistic effect of multiple elements (Fe, Co, Ni, Al, Ta, Si, C), the performance of the fiber material exhibits the characteristics of multiphase stabilization, so that the multiphase stabilization of the alloy fiber prepared by the present invention can inhibit the performance degradation caused by grain boundary sliding or precipitation phases during heat treatment or high-temperature service, and further promote the high-entropy alloy to form a stable FCC single-phase structure with excellent plasticity and crack resistance. In particular, under high-temperature environments, the FCC structure exhibits stronger creep resistance and fatigue resistance.

[0013] In a possible implementation, in step S2, the smelting condition is to smelt at least 3 times.

[0014] Compared with the existing technology, the above technical scheme optimizes the composition uniformity and internal quality of the master alloy by adopting at least three smelting times, significantly improves the purity, mechanical properties and soft magnetic properties of the material, overcomes the problems of composition segregation, unstable performance and subsequent processing defects caused by insufficient smelting times in the existing technology, and lays the foundation for the preparation of high-performance, high-temperature resistant soft magnetic high-entropy alloy fibers.

[0015] In a possible implementation manner, in step S2, the master alloy rod has a diameter of 5-10 mm and a length of 6-12 cm.

[0016] Compared with the prior art, by adopting the above technical scheme, when the diameter and length of the master alloy rod are controlled within the above range, it is possible to ensure that the alloy rod has good dimensional stability, avoid the problem of too fast heat loss caused by too small size, or incomplete smelting and uneven cooling caused by too large size, further reduce the influence of internal and external temperature difference on the uniformity of metal composition, reduce the structural defects caused by thermal stress, and this size range can ensure that under the action of the injection pressure, the molten liquid can be sprayed stably and continuously to form high-entropy alloy fibers with uniform diameter, optimize the key process steps of smelting, suction casting and injection cooling, significantly improve the dimensional consistency, internal quality and comprehensive performance of the high-entropy alloy fibers, and at the same time solve the problems of unstable fiber quality and low production efficiency caused by unreasonable size in the prior art.

[0017] In a possible implementation, in step S3, the protective gas is argon, and the purity of the argon is above 99.9 wt.%.

[0018] Compared with the existing technology, the above technical scheme can effectively isolate oxygen, nitrogen and other impurity gases by using high-purity argon as a protective gas, prevent the high-entropy alloy from undergoing chemical reactions such as oxidation and nitridation when in contact with air under high temperature conditions, significantly reduce the formation of oxides on the surface of the high-entropy alloy fiber, and ensure the smoothness and integrity of the fiber surface.

[0019] In a possible implementation, in step S3, the coil heating condition is: heating by a copper coil, a rotation speed of 230-400 rad / min, and a heating temperature of 1650°C.

[0020] Compared with the prior art, the above technical solution can maintain good fluidity and uniformity of the molten liquid before spraying by rotating at a speed of 230-400 rad / min, while avoiding component segregation caused by static heating. The heating temperature is further optimized to 1650°C, ensuring sufficient melting of the master alloy rod and uniform distribution of the elements, while avoiding element volatilization and grain coarsening caused by excessive temperature.

[0021] In a possible implementation, in step S3, the container is a glass tube, and the diameter of the injection port of the glass tube is 160-260 μm, and the injection pressure is 0.5-6.0 MPa.

[0022] Compared with the prior art, the above technical solution is adopted to set the glass tube as the container because the glass tube has good thermal stability and chemical inertness, which can prevent the molten liquid from reacting with the container before spraying. At the same time, its smooth surface can reduce the flow resistance of the molten liquid, further improving the stability of the spraying process. The diameter of the glass tube nozzle is limited to 160-260 μm, which can ensure that the molten liquid forms a thin stream during the spraying process. The diameter of the fiber after cooling can be controlled within a smaller range to avoid the appearance of too thick or too thin fibers. The spray pressure range is 0.5-6.0 MPa. The spray speed and flow rate of the molten liquid can be accurately adjusted through pressure control to avoid uneven shape or breakage of the fiber due to excessive or too small flow rate during the cooling process.

[0023] In a possible implementation, in step S3, the temperature of the annealing treatment is 600-950°C.

[0024] Compared with the existing technology, the above technical scheme sets the annealing temperature to 600-950°C, which can control the recrystallization process of the alloy fiber, make the internal structure of the fiber more uniform, and effectively reduce the internal stress, improve the mechanical properties and magnetic properties of the fiber. Within this temperature range, the γ′ phase and other strengthening phases in the high entropy alloy fiber can be evenly distributed, while avoiding the precipitation of the second phase, ensuring the structural stability of the alloy fiber.

[0025] Another technical problem to be solved by the present invention is to provide a high-temperature resistant soft magnetic high-entropy alloy fiber to solve the problems of unstable soft magnetic properties, insufficient high-temperature strength, poor ductility and many processing defects existing in conventional alloy fibers in the prior art.

[0026] In order to overcome the above defects of the prior art, the present invention provides a high temperature resistant soft magnetic high entropy alloy fiber, and the alloy fiber is prepared by the above preparation method.

[0027] Compared with the prior art, the high temperature resistant soft magnetic high entropy alloy fiber of the present invention has the following advantages: the alloy fiber prepared by the present invention overcomes the common problems of unstable soft magnetic properties, insufficient high temperature strength, poor ductility and many processing defects in the prior art, and has excellent soft magnetic properties. The high saturation magnetization capacity ensures the sensitivity and stability in a complex electromagnetic environment, and the low coercive force makes its magnetic properties easy to control and reduces energy loss. The mechanical properties of the fiber are also significantly optimized, with excellent high temperature strength and deformation resistance, and can maintain structural integrity under extreme high temperature conditions; in addition, the ductility of the fiber of the present invention is significantly improved, with good toughness and plasticity, and can avoid brittle fracture under stress conditions, and the dimensional accuracy and surface finish of the fiber are greatly improved, effectively reducing the influence of surface defects. In summary, the high temperature resistant soft magnetic high entropy alloy fiber of the present invention has achieved comprehensive improvement in mechanical properties, magnetic properties and dimensional stability, and is suitable for high-end electronic equipment, magnetic sensors and high-performance applications in extreme environments.

[0028] In a possible implementation, the soft magnetic high entropy alloy fiber has a saturation magnetization of ≥145 emu / g, a coercive force of ≤10Oe, a diameter of ≤200 μm and a tensile elongation of ≥20%.

[0029] Compared with the prior art, the high saturation magnetization intensity (≥145 emu / g) of the fiber of the present invention ensures high sensitivity and excellent magnetic response performance in complex magnetic fields by adopting the above technical scheme; the low coercive force (≤10 Oe) reduces hysteresis loss, making the fiber suitable for high-performance magnetic sensors and electromagnetic shielding materials; the setting of diameter ≤200μm significantly improves the dimensional uniformity and precision of the fiber, ensuring the stable performance of the fiber in practical applications; the significant improvement of tensile elongation ≥20% indicates that the fiber can maintain sufficient toughness and fracture resistance under mechanical processing and high strain conditions. Ultimately, the soft magnetic high entropy alloy fiber of the present invention can simultaneously meet the requirements of high soft magnetic properties, high mechanical properties and dimensional accuracy, and remain stable under extreme conditions such as complex magnetic fields, high temperatures and high stresses, providing an important high-performance material choice for high-end electronic equipment, magnetic sensors, and aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The XRD diagrams of the high entropy alloy fiber materials prepared in Examples 1-4 and Comparative Examples; Figure 2 EBSD images of high entropy alloy fiber materials prepared in Examples 1-4 and Comparative Examples; Figure 3 The tensile stress-strain diagram of the high entropy alloy fiber material prepared in Examples 1-4 and Comparative Examples; Figure 4The VSM diagram of the high entropy alloy fiber material prepared in Examples 1-4 and Comparative Examples; Figure 5 The stress impedance diagrams of the high entropy alloy fiber materials prepared in Examples 1-4 and the comparative example. DETAILED DESCRIPTION

[0031] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present invention, and are not intended to limit the protection scope of the embodiments of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0032] The present invention provides a method for preparing a high temperature resistant soft magnetic high entropy alloy fiber, comprising the following steps: S1: Using atomic percentage Fe a Co b Ni c Al d Ta e Si f C g Weigh a single metal raw material according to the chemical formula of , wherein a> 25, b> 25, c> 25, 0≤d≤20, 0≤e≤20, 0≤f≤20, 0≤g≤20, and a+b+c+d+e+f+g= 100, and mix them uniformly to obtain a mixed metal raw material; S2: melting the mixed metal raw material obtained in step S1 in a high vacuum arc melting furnace to obtain a button-shaped master alloy, and then obtaining a master alloy rod by suction casting; S3: putting the master alloy rod obtained in the step S2 into a container, and introducing a protective gas into the container, then heating the master alloy rod to 1450-1650° C. by coil heating, and obtaining a molten liquid after the master alloy rod is melted. The molten liquid is ejected from the ejection port of the container under the action of the protective gas pressure, and cooled by cooling water to obtain a high entropy alloy fiber, which is then further annealed to obtain a high temperature resistant soft magnetic high entropy alloy fiber.

[0033] As a preferred solution, in step S1, the Fe a Co b Ni c Al d Ta e Si f C g The chemical formula is Fe 34 Co 29 Ni 29 Al3Ta2Si2C1.

[0034] As a preferred solution, in step S2, the smelting condition is to smelt at least 3 times.

[0035] As a preferred solution, in step S2, the diameter of the master alloy rod is 5-10 mm and the length is 6-12 cm.

[0036] As a preferred solution, in step S3, the protective gas is argon, and the purity of the argon is above 99.9wt.%.

[0037] As a preferred solution, in step S3, the coil heating conditions are: heating by a copper coil, a rotation speed of 230-400 rad / min, and a heating temperature of 1650°C.

[0038] As a preferred solution, in step S3, the container is a glass tube, and the diameter of the injection port of the glass tube is 160-260 μm, and the injection pressure is 0.5-6.0 MPa.

[0039] As a preferred solution, in step S3, the temperature of the annealing treatment is 600-950°C.

[0040] The present invention also provides a high-temperature resistant soft magnetic high-entropy alloy fiber, and the alloy fiber is prepared by the above-mentioned preparation method.

[0041] As a preferred solution, the saturation magnetization of the soft magnetic high entropy alloy fiber is ≥145 emu / g, the coercive force is ≤10Oe, the diameter is ≤200 μm and the tensile elongation is ≥20%.

[0042] The present invention significantly improves the comprehensive performance of the fiber by comprehensively optimizing the composition design and preparation process of the high-temperature resistant soft magnetic high entropy alloy fiber. By rationally designing the chemical composition and combining high vacuum arc melting with suction casting process, the composition uniformity and high purity of the alloy matrix are ensured, and the performance instability problem caused by composition segregation in conventional processes is avoided. Furthermore, the glass tube injection molding process is adopted, combined with the precise control of the injection nozzle diameter (160-260 μm) and the protective gas pressure (0.5-6.0 MPa), which not only achieves the uniformity and dimensional stability of the fiber diameter, making the fiber diameter ≤200 μm, but also effectively reduces the oxidation defects and cracks on the fiber surface, and improves the surface quality and internal density. At the same time, by optimizing the coil heating process and the spray temperature control (1450-1650℃), the fluidity of the molten liquid and the stability of the spray forming are ensured. The optimization of the annealing treatment (600-950℃) significantly improves the grain structure of the fiber, suppresses the annealing brittleness, and improves the ductility of the fiber, so that the tensile elongation reaches ≥20%, and maintains excellent mechanical properties and high temperature stability. In addition, by reasonably controlling the proportion of multiple principal components and optimizing the process parameters, the soft magnetic properties of the fiber are greatly improved, the saturation magnetization intensity reaches ≥145 emu / g, the coercive force is ≤10 Oe, and the magnetic properties can be maintained even in a high temperature environment. In general, the high-temperature resistant soft magnetic high entropy alloy fiber prepared by the present invention not only far exceeds the existing technology in terms of mechanical properties, soft magnetic properties and high-temperature stability, but also has excellent dimensional uniformity and processing performance, which can meet the needs of magnetic sensors, high-temperature electronic devices and other fields for high-performance soft magnetic fiber materials.

[0043] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, which should be included in the protection scope of the present invention. In the following examples, Fe a Co b Ni c Al d Ta e Si f C g The specific chemical formula and ratio are for reference only, and the chemical formulas within the above-mentioned scope of the present invention are all within the protection scope of the present invention.

[0044] Embodiment 1: This embodiment provides a method for preparing a high temperature resistant soft magnetic high entropy alloy fiber, which specifically comprises the following steps: S1: Mixed metal raw materials According to the atomic percentage of Fe 32 Co 29 Ni 29 The chemical formula of Al3Ta3Si2C2 is adopted, and single metal raw materials are weighed, wherein the mass percentage of each element is: Co: 29%, Al: 3%, Fe: 32%, Ni: 29%, Ta: 3%, Si: 2%, C: 2%. Pure metal particles with a purity of 99.95wt.% are selected as raw materials, and the oxide film on the surface is removed with a steel brush, and ultrasonic cleaning is carried out in anhydrous ethanol for 2 minutes to remove oil and impurities, and then the mixture is dried with cold wind for use, and each single metal particle is weighed using an electronic balance with an accuracy of 0.0001g, and mixed evenly according to proportion to obtain a mixed metal raw material.

[0045] S2: Melting and suction casting The mixed metal raw material obtained in step S1 is placed in a high vacuum arc melting furnace and evacuated to 1×10 -2 Pa, and then high-purity argon with a purity of 99.9wt.% was introduced. The smelting was carried out under the condition of a current of 500A, and the heating rate of the smelting furnace was controlled to be 15℃ / min and the cooling rate was 6℃ / min. After smelting, the alloy melt was cast into a copper mold and cooled to room temperature. The resulting ingot was turned over and smelted repeatedly for 3 times to ensure the uniformity of the alloy composition. Subsequently, the alloy melt was prepared into a master alloy rod with a diameter of 8 mm and a length of 10 cm by a suction casting process.

[0046] S3: Spray cooling and annealing The master alloy rod obtained in step S2 is placed in a glass tube, and high-purity argon gas with a purity of 99.9wt.% is introduced into the glass tube as a protective gas. The master alloy rod is heated by a copper coil heating device at a rotation speed of 300 rad / min to 1650°C, so that the master alloy rod is completely melted and a uniform molten liquid is formed. Under the action of argon pressure of 0.8 MPa, the molten liquid is ejected from the glass tube injection port (with a diameter of 200 μm) and rapidly cooled by cooling water to obtain a high entropy alloy fiber with uniform diameter.

[0047] Subsequently, the obtained high entropy alloy fiber was annealed under the following annealing conditions: keeping at 800°C for 20 minutes and immediately water quenching after annealing to ensure the uniformity of the internal structure of the fiber and reduce internal stress.

[0048] Embodiment 2: Example 2 also provides a method for preparing high-temperature resistant soft magnetic high-entropy alloy fibers. The preparation steps are similar to those of Example 1. The only difference is that the annealing conditions are different, specifically: the annealing temperature is 800°C and the holding time is 60 minutes.

[0049] Embodiment 3: Example 3 also provides a method for preparing high-temperature resistant soft magnetic high-entropy alloy fibers. The preparation steps are similar to those of Example 1. The only difference is that the annealing conditions are different, specifically: the annealing temperature is 800°C and the holding time is 120 minutes.

[0050] Embodiment 4: Example 4 also provides a method for preparing high-temperature resistant soft magnetic high-entropy alloy fibers. The preparation steps are similar to those of Example 1. The only difference is that the annealing conditions are different, specifically: the annealing temperature is 800°C and the holding time is 13h.

[0051] Embodiment 5: This embodiment provides a method for preparing high temperature resistant soft magnetic high entropy alloy fiber, and the specific steps are as follows: S1: Mixed metal raw materials According to the atomic percentage of Fe 33 Co 27 N i28 Al5Ta2Si4C1 chemical formula, weigh the single metal raw materials. Select Fe, Co, Ni, Al, Ta, Si and C single metal particles with a purity of 99.95wt.%, use a steel brush to remove the oxide film, ultrasonically clean in anhydrous ethanol for 2 minutes to remove oil and impurities, and then blow dry with cold air for use. Use an electronic balance with an accuracy of 0.0001g to weigh each single metal raw material in proportion and mix them evenly to obtain a mixed metal raw material.

[0052] S2: Melting master alloy The mixed metal raw material obtained in step S1 is placed in a high vacuum arc melting furnace for melting. The melting conditions are high vacuum (vacuum degree 1.1×10 -2 Pa), argon gas with a purity of 99.9wt.% was introduced to protect the metal raw materials. The metal raw materials were melted in order from low to high melting points. After 5 times of turning over and melting, the raw materials were evenly mixed to obtain a button-shaped master alloy. Subsequently, the master alloy was cast into a master alloy rod with a diameter of 5 mm and a length of 12 cm by a suction casting process.

[0053] S3: Sprayed Fiber Forming and Annealing The master alloy rod prepared in step S2 is placed in a glass tube container, the diameter of the nozzle of the container is 160 μm, and argon gas with a purity of 99.9wt.% or more is introduced for protection. The master alloy rod is heated by a copper coil, and the speed of the coil is set to 230 rad / min. The master alloy rod is heated to 1450°C, and a molten liquid is obtained after the master alloy rod is completely melted. The molten liquid is ejected from the nozzle using an argon injection pressure of 0.5 MPa, and then rapidly cooled by cooling water to form a high entropy alloy fiber.

[0054] Next, the high entropy alloy fiber obtained by spraying was placed in a vacuum environment for annealing at a temperature of 600°C for 30 min, and then immediately water quenched to obtain a high-temperature resistant soft magnetic high entropy alloy fiber with excellent soft magnetic properties.

[0055] Example 6 This embodiment provides a method for preparing high temperature resistant soft magnetic high entropy alloy fiber, and the specific steps are as follows: S1: Mixed metal raw materials According to the atomic percentage of Fe 35 Co 30 N i30 Al3Ta1Si1 chemical formula, weigh the single metal raw materials. Select Fe, Co, Ni, Al, Ta, Si single metal particles with a purity of 99.95wt.%, use a steel brush to remove the oxide film, ultrasonically clean in anhydrous ethanol to remove oil and impurities, then blow dry with cold air for use, use an electronic balance with an accuracy of 0.0001g, weigh each single metal raw material in proportion and mix them evenly to obtain a mixed metal raw material.

[0056] S2: Melting master alloy The mixed metal raw material obtained in step S1 is placed in a high vacuum arc melting furnace for melting. The melting conditions are high vacuum (vacuum degree 1.5×10 -2 Pa), argon gas with a purity of 99.9wt.% was introduced to protect the metal raw materials. The metal raw materials were melted in order from low to high melting points. After 4 times of turning over and melting, the raw materials were evenly mixed to obtain a button-shaped master alloy. Subsequently, the master alloy was cast into a master alloy rod with a diameter of 10 mm and a length of 12 cm by a suction casting process.

[0057] S3: Sprayed Fiber Forming and Annealing The master alloy rod prepared in step S2 is placed in a glass tube container, the diameter of the nozzle of the container is 260 μm, and argon gas with a purity of more than 99.9wt.% is introduced for protection. The master alloy rod is heated by a copper coil, and the speed of the coil is set to 400 rad / min. The master alloy rod is heated to 1650°C, and a molten liquid is obtained after the master alloy rod is completely melted. The molten liquid is ejected from the nozzle using an argon injection pressure of 6.0 MPa, and then rapidly cooled by cooling water to form a high entropy alloy fiber.

[0058] Next, the high entropy alloy fiber obtained by spraying was placed in a vacuum environment for annealing at a temperature of 800°C for 60 min, and then immediately water quenched to obtain a high-temperature resistant soft magnetic high entropy alloy fiber with excellent soft magnetic properties.

[0059] Comparative Example: The comparative example provides a method for preparing high-temperature resistant soft magnetic high-entropy alloy fibers, and its preparation steps are similar to those of Example 1, except that the alloy fibers of the comparative example are not annealed, but are rapidly cooled in cooling water to obtain high-entropy alloy fibers with uniform diameter, which are named quenched fibers.

[0060] The above-mentioned embodiments 1-4 of the present invention and the comparative example were subjected to performance analysis and comparison, and the specific tests were as follows: 1. XRD analysis was performed on the four annealed fibers of Examples 1-4 and the fibers of the comparative example. Figure 1 As shown. It can be seen that the high entropy alloy fibers annealed for a long time are all FCC structures, and no second phase is precipitated, which proves that the phase structure of the high entropy alloy fiber of the present invention can remain stable after long-term annealing;

[0061] 2. Take the four annealed high entropy alloy fibers of Examples 1-4 and the fibers of the comparative example, and perform EBSD tests on each group of samples. The specific process of high temperature friction and wear test is as follows: first, polish the fibers with 800, 1200, 1500, and 2000 mesh sandpaper, and then clean them with alcohol; then polish the fiber surface with a vibration polishing device, the polishing voltage is 90 V, and the polishing time is 2 h, and then use EBSD to test the grain size and orientation of the fibers. The quenched samples are used as the control group to perform the same experiment. The results are shown in Figure 2. Figure 2 As shown, it can be seen that with the increase of annealing time, the grain size and orientation do not change, the grain size is about 59 um, and the orientation is random, indicating that the present invention has excellent high temperature stability.

[0062] 3. Take the four annealed high entropy alloy fibers of Examples 1-4 and the fibers of the comparative example, and perform tensile stress-strain tests on each group of samples. The specific test process is: first, prepare the samples according to ASTM D3379-75 standard, and then use a universal testing machine to perform tensile tests at room temperature, with a tensile strain rate of 5×10-3 / s. The test results are as follows: Figure 3 As shown, the ultimate stress strength and engineering strain rate are shown in Table 1. In Table 1, the quenched state is the fiber of the comparative example, and the following corresponds to the fibers of Examples 1-4 in sequence:

[0063] Table 1: Ultimate stress strength and engineering strain rate of alloys Figure 3 The results in Table 1 show that the ultimate tensile strength and elongation of the FCC single-phase high entropy alloy fiber prepared by the present invention will not decrease with increasing annealing time, and the mechanical properties have excellent thermal stability.

[0064] 4. Take the four annealed high entropy alloy fibers of Examples 1-4 and the fibers of the comparative example, and perform VSM tests on each group of samples. The specific test process is: the fibers are cut into a length of 3 mm, and then arranged in a cross shape to avoid magnetic anisotropy during the test. In order to make the coercivity test more accurate, the sampling frequency is 2 Oe / point in the range of -50 to 50 Oe, and 500 Oe in the rest range. The test results are shown in Figure 2. Figure 4 The saturation magnetization and coercive force are shown in Table 2.

[0065] Table 2: Alloy saturation magnetization and coercivity Figure 4 The results in Table 2 show that the saturation magnetization and coercive force of the FCC single-phase high entropy alloy fiber prepared by the present invention will not deteriorate with increasing annealing time, and the soft magnetic properties have excellent thermal stability.

[0066] 5. Take the four annealed high entropy alloy fibers of Examples 1-4 and the fibers of the comparative example, and perform stress impedance tests on each group of samples. The specific test process is: cut the fiber into 10 cm lengths, then weld it on the circuit board with connectors on both sides, connect the circuit board to the connector of the vector network analyzer, and test it in the 0-2 GHz range. The test results are as follows: Figure 5 As shown, Figure 5 The results show that the reflection coefficient of the FCC single-phase high entropy alloy fiber prepared by the present invention does not change with the annealing time and has excellent stability, which is conducive to its application in high-temperature sensors.

[0067] Through the above embodiments, it is further proved that the present invention provides a high temperature resistant soft magnetic high entropy alloy fiber and a preparation method thereof. By combining high vacuum arc melting, suction casting and spray cooling processes, the composition uniformity and purity of the high entropy alloy master alloy are optimized, and alloy fibers with high dimensional consistency and smooth surface are prepared by the spray process. Through specific composition design and multiple smelting, the FCC single-phase structure of the alloy is ensured, the problem of precipitation phase or tissue separation is avoided, and the fiber has excellent thermal stability and creep resistance in a high temperature environment. Furthermore, by controlling the annealing temperature (600-950°C) and time, and adopting a rapid water quenching process, the annealing brittleness problem is effectively avoided, and the ductility and mechanical properties of the fiber are greatly improved.

[0068] The high entropy alloy fiber prepared by the present invention has achieved comprehensive optimization in terms of mechanical properties and magnetic properties, overcoming the technical problems of unstable soft magnetic properties, insufficient high temperature strength, poor ductility and many processing defects in the prior art. The fiber exhibits excellent soft magnetic properties of high saturation magnetization (≥145 emu / g) and low coercivity (≤10 Oe), and has excellent high temperature strength and tensile elongation (≥20%). In addition, the process optimization of injection molding significantly improves the dimensional accuracy and surface quality of the fiber, ensuring that the fiber diameter is uniform and ≤200μm.

[0069] In summary, the present invention is significantly superior to the prior art in key performance indicators such as soft magnetic properties, high-temperature stability, mechanical properties and dimensional consistency through innovations in component design and process control, successfully solving the bottleneck problems in the prior art. The prepared high-temperature resistant soft magnetic high-entropy alloy fiber is suitable for magnetic sensors, high-end electronic equipment and high-performance applications in extreme environments, and has broad market prospects and important technical value.

[0070] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0071] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing high temperature resistant soft magnetic high entropy alloy fiber, characterized in that: The following steps are involved: S1: Using atomic percentage Fe a Co b Ni c Al d Ta e Si f C g Weigh a single metal raw material according to the chemical formula of , wherein a>25, b>25, c>25, 0≤d≤20, 0≤e≤20, 0≤f ≤20, 0≤g≤20, and a+b+c+d+e+f+g=100, and mix them uniformly to obtain a mixed metal raw material; S2: melting the mixed metal raw material obtained in step S1 in a high vacuum arc melting furnace to obtain a button-shaped master alloy, and then obtaining a master alloy rod by suction casting; S3: putting the master alloy rod obtained in the step S2 into a container, and introducing a protective gas into the container, then heating the master alloy rod to 1450-1650° C. by coil heating, and obtaining a molten liquid after the master alloy rod is melted. The molten liquid is ejected from the ejection port of the container under the action of the protective gas pressure, and cooled by cooling water to obtain a high entropy alloy fiber, which is then further annealed to obtain a high temperature resistant soft magnetic high entropy alloy fiber.

2. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 1, characterized in that: In the step S1, the Fe a Co b Ni c Al d Ta e Si f C g The chemical formula is Fe 34 Co 29 Ni 29 Al3Ta2Si2C1.

3. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 1, characterized in that: In the step S2, the smelting condition is to smelt at least 3 times.

4. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 1, characterized in that: In step S2, the master alloy rod has a diameter of 5-10 mm and a length of 6-12 cm.

5. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 1, characterized in that: In the step S3, the protective gas is argon, and the purity of the argon is above 99.9wt.%.

6. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 1, characterized in that: In step S3, the coil heating conditions are: heating by a copper coil, a rotation speed of 230-400 rad / min, and a heating temperature of 1650°C.

7. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 6, characterized in that: In the step S3, the container is a glass tube, and the diameter of the injection port of the glass tube is 160-260 μm, and the injection pressure is 0.5-6.0 MPa.

8. The method for preparing high temperature resistant soft magnetic high entropy alloy fiber according to claim 6, characterized in that: In the step S3, the temperature of the annealing treatment is 600-950°C.

9. A high temperature resistant soft magnetic high entropy alloy fiber, characterized in that: The alloy fiber is prepared by the preparation method according to any one of claims 1 to 8.

10. The high temperature resistant soft magnetic high entropy alloy fiber according to claim 9, characterized in that: The soft magnetic high entropy alloy fiber has a saturation magnetization intensity of ≥145 emu / g, a coercive force of ≤10Oe, a diameter of ≤200 μm and a tensile elongation of ≥20%.

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