Rotary induction melting device and preparation method of high-entropy alloy powder

Abstract

The invention relates to the technical field of alloy powder preparation, and discloses a high-entropy alloy powder rotating induction melting device and a preparation method, the device comprises a vacuum melting unit integrated with a rotating magnetic field generating unit, a graded feeding control system, a gas atomization unit, a powder collecting unit and a vacuum and atmosphere control system, the rotating magnetic field unit comprises an octupole symmetrical electromagnetic coil for driving the melt to rotate to realize electromagnetic stirring; the feeding control system is divided into a main feeding bin and a secondary feeding device and is used for sequentially adding high-melting-point raw materials and elements Al and Mn easy to burn out; the method comprises the following steps: sequentially carrying out vacuum melting on pretreated raw materials according to melting points, and applying a rotating magnetic field for stirring; refining after supplementing elements easy to burn out; the melt is guided into a tundish, and powder is prepared through gas atomization of a supersonic annular nozzle; according to the method, the problem of segregation of components of the high-entropy alloy is solved through intensified stirring and graded feeding of the rotating magnetic field.

Description

Technical Field

[0001] This invention belongs to the field of alloy powder preparation technology, specifically relating to a rotary induction melting device and preparation method for high-entropy alloy powder. Background Technology

[0002] High-entropy alloys exhibit excellent mechanical properties, corrosion resistance, and wear resistance due to their unique high-entropy effect, lattice distortion effect, and hysteresis diffusion effect, and have broad application prospects in surface engineering, additive manufacturing, and other fields. Their performance is highly dependent on the uniformity of their composition.

[0003] Currently, the preparation of high-entropy alloy powder typically employs a two-step method: first, alloy ingots are prepared through vacuum arc melting or conventional vacuum induction melting, followed by powder production via gas atomization or plasma rotating electrode method. However, traditional melting methods struggle to completely resolve the melt composition segregation problem caused by the multiple principal elements and high melting point differences in high-entropy alloys, easily leading to dendrites or intermetallic compounds in the ingot, affecting the compositional uniformity and performance of the subsequently atomized powder. While conventional induction melting can stir the melt, the stirring direction is singular and the intensity is limited, resulting in poor homogenization of high-viscosity high-entropy alloy melts. Furthermore, for alloys containing easily burnable elements such as Al and Mn, precisely controlling the composition during the melting process remains a significant challenge. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a rotary induction melting device for high-entropy alloy powder, comprising: a vacuum melting unit, a feeding control system, a gas atomization unit, a powder collection unit, and a vacuum and atmosphere control system. The vacuum melting unit includes a vacuum chamber, a rotating magnetic field generating unit, and an induction heating system disposed within the vacuum chamber; the induction heating system includes a medium-frequency induction power supply and a copper main induction coil, with a water-cooled copper crucible placed inside the copper main induction coil; the rotating magnetic field generating unit is used to generate a rotating magnetic field during the melting process to drive the melt inside the water-cooled copper crucible to rotate. The feeding control system includes a main feeding bin located at the top of the vacuum chamber and a secondary feeding device connected to the middle of the vacuum chamber, for adding raw materials in stages; The gas atomization unit forms a molten metal flow by vertically impacting the melt with inert gas, atomizing the molten metal flow into droplets, and the droplets cool and solidify during flight to form alloy powder. The powder collection unit is located below the gas atomization unit and is used to collect the alloy powder after cooling and solidification. The vacuum and atmosphere control system is used to evacuate and fill the cavities of the vacuum melting unit and the gas atomization unit with protective gas.

[0005] Furthermore, the rotating magnetic field generating unit includes a medium-frequency power supply and an electromagnetic coil group; the multiple electromagnetic coils in the electromagnetic coil group are symmetrically distributed in an octagonal pattern and driven by the medium-frequency power supply. The electromagnetic coil group is installed around the copper main induction coil. The phase and frequency of the current input to the electromagnetic coil group are adjusted by a programmable logic controller to generate a rotating electromagnetic force in the melt inside the water-cooled copper crucible.

[0006] Furthermore, the main feeding bin is fixed to the top flange of the vacuum chamber, and the bottom of the bin is equipped with a high-sealing pneumatic gate valve and an integrated weighing sensor; the secondary feeding device is laterally connected to the middle of the vacuum chamber through a vacuum locking chamber, and is used to supplement aluminum and manganese elements into the vacuum chamber during the smelting process.

[0007] Furthermore, the gas atomization unit includes a flow guiding system, an intermediate tundish connected to the bottom of the water-cooled copper crucible via the flow guiding system, a gas supply system, an atomization tower, and a supersonic annular nozzle arranged around the outlet of the intermediate tundish.

[0008] Furthermore, the flow guiding system includes a vertically installed flow guiding pipe and a stopper rod mechanism. The intermediate package is located at the top of the atomizing tower and is connected to the lower end of the flow guiding pipe via a flange. The supersonic annular nozzle has six symmetrical nozzle holes evenly distributed on its annular surface, and the spray angle can be adjusted. The gas supply system provides an inert gas medium for atomization. The atomizing tower is an upright stainless steel cylinder with a mirror-polished inner surface.

[0009] Furthermore, the powder collection unit is located below the gas atomization unit and includes a cooling system, subsequent processing equipment, and a graded collection system; The cooling system includes a cooling tower and a circulating water cooling jacket surrounding the tower wall, as well as an annular nitrogen curtain air inlet at the top of the cooling tower, which together achieve rapid solidification and cooling of the alloy powder. The graded collection system consists of a primary cyclone separator and a secondary bag filter connected in series. At the end of the graded collection system, multiple dust collection tanks are connected for replacing and transferring metal powder under an inert atmosphere. Subsequent processing equipment includes a vibrating screen connected to the outlet of the powder collection tank, used to screen the powder into target particle size ranges.

[0010] On the other hand, a method for preparing high-entropy alloy powder based on the above-mentioned device is also proposed, including the following steps: After cleaning the surface of the raw materials, they are batched according to the target high-entropy alloy composition, and a burn-off compensation amount is preset for easily burnable elements. All raw materials except for easily burnable elements are placed in a water-cooled copper crucible in the vacuum melting unit according to their melting points from high to low. Inert gas is introduced under vacuum, and the raw materials are completely melted through an induction heating system to obtain a melt. Simultaneously, a rotating magnetic field is applied during the melting process to drive the melt to rotate continuously for electromagnetic stirring. Easily burnable elements with burn-off compensation are added to the melt through a feeding control system to continue melting. Subsequently, the temperature is raised and held for degassing and composition homogenization. The refined high-entropy alloy melt is introduced into an intermediate ladle through a guide pipe to form a molten metal flow. A supersonic annular nozzle is used to vertically impact the molten metal flow with inert gas, atomizing it into droplets. The droplets cool and solidify during flight to form metal powder. The metal powder is collected and sieved to obtain high-entropy alloy powder within the target particle size range.

[0011] Furthermore, the purity of the raw material is not less than 99.5 wt.%, and the surface of the raw material is mechanically cleaned to remove oxide scale and impurities; the easily burnable elements include at least one of aluminum and manganese.

[0012] Furthermore, the process of filling an inert gas in a vacuum environment and completely melting the raw material through an induction heating system to obtain a melt is as follows: after the vacuum degree is evacuated to below 0.1 Pa, inert gas is filled to 0.9 × 10⁻⁶ Pa. 5 -1.1×10 5 Pa; the induction heating temperature is 1350-1400℃, the rotating magnetic field drives the melt to rotate at a speed of 10-30 rpm, and the electromagnetic stirring time is 20-30 minutes.

[0013] Furthermore, the collected powder was vacuum dried at 80-120℃ for 1-3 hours, and then sieved to obtain high-entropy alloy powder with a particle size range of 15-53μm.

[0014] Compared with the prior art, the present invention has the following significant advantages: By introducing a controllable rotating magnetic field for active electromagnetic stirring, the limitations of traditional induction melting eddy currents are broken, and strong convection of the melt in three-dimensional space is realized. This effectively overcomes the problems of slow diffusion and easy segregation between high-entropy alloy components, and ensures the extreme uniformity of the melt's microstructure.

[0015] By adopting a staged feeding strategy, high-melting-point, non-burnable elements are first melted and preliminarily homogenized, and then easily burnable elements are added. Combined with a preset burn-off compensation amount, the loss of elements through volatilization is minimized, and precise control of the target composition is achieved.

[0016] By combining rotary induction melting with online gas atomization powder production, compositional fluctuations and energy losses caused by ingot remelting are avoided, enabling continuous, short-process production from raw materials to high-performance powders.

[0017] Because the precursor melt is uniform, clean and has good fluidity, the powder obtained after atomization has high sphericity, few satellite powders, low hollow powder rate and low oxygen content. Its fluidity and bulk density are excellent, making it particularly suitable for supersonic spraying and additive manufacturing processes with strict requirements for powder quality.

[0018] Coatings or components prepared from this powder exhibit higher hardness and superior corrosion and wear resistance due to their uniform composition and defect-free microstructure, resulting in a significant improvement in overall performance compared to materials prepared by traditional methods. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the high-entropy alloy powder preparation method of the present invention; Figure 2 This is a schematic diagram of the rotary induction melting apparatus of the present invention; Figure 3 This is a schematic diagram of the structure of the gas atomization unit in the embodiment; Figure 4 This is a schematic diagram of the structure of the supersonic annular nozzle in the embodiment; The components include: 1. Feeding control system; 2. Vacuum melting unit; 3. Vacuum and atmosphere control system; 4. Gas atomization unit; 5. Powder collection unit; 6. Supersonic annular nozzle; 7. Gas supply system; 8. Atomization tower; 9. Melt; and 10. Tundish. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, but the implementation and protection scope of this invention are not limited thereto.

[0021] This invention provides a method for preparing high-entropy alloy powder based on rotational induction melting, such as... Figure 1 As shown, it includes the following steps: S1. Raw material pretreatment and batching Select metal bulk raw materials with a purity of not less than 99.5 wt.%, and mechanically clean their surfaces to remove oxide scale and impurities; formulate the raw materials according to the atomic percentage of the target high-entropy alloy, and pre-set a burn-off compensation amount of 5-15% for at least one easily burnable element in Al and Mn.

[0022] In one embodiment, the atomic percentages of the target high-entropy alloy are: Al 8 at.%, Fe 20 at.%, Co 20 at.%, Ni 20 at.%, Cr 20 at.%, Mo 12 at.%.

[0023] S2. Staged vacuum induction melting and electromagnetic stirring In step S1, all raw materials except for easily burnable elements are placed into the water-cooled copper crucible of the vacuum melting unit in descending order of their melting points; after evacuating to below 0.1 Pa, inert gas is introduced to a pressure of 0.9 × 10⁻⁶ Pa. 5 -1.1×10 5 Pa; Start the induction heating system and the medium-frequency rotating magnetic field device, heat to 1350-1400℃ to completely melt the raw materials, and drive the melt to rotate continuously at a speed of 10-30 rpm through the rotating magnetic field during the melting process, and the electromagnetic stirring time is 20-30 minutes. S3. Refining and Ingredient Fine-tuning The easily burnable element is added to the melt obtained in step S2 through the feeding control system, and the melting continues for 5-10 minutes; then the melt temperature is raised to 1580-1650℃ and held for 15-25 minutes for degassing and component homogenization. S4. Gas atomization powder production The high-entropy alloy melt refined in step S3 is introduced into the intermediate tundish through a guide pipe to form a stable molten metal flow; a supersonic annular nozzle is used to vertically impact the molten metal flow with inert gas at a pressure of 0.5-0.7 MPa, atomizing it into tiny droplets, which cool and solidify into powder during flight. S5. Powder Collection and Processing The powder obtained in step S4 is collected, and after classification, drying and sieving, high-entropy alloy powder within the target particle size range is obtained.

[0024] The present invention also provides a rotary induction melting apparatus for high-entropy alloy powder, such as... Figure 2 As shown, it includes: I. Vacuum Melting Unit It includes a vacuum chamber, a rotating magnetic field generating unit, and an induction heating system installed inside the vacuum chamber.

[0025] The main body of the vacuum chamber is a cylindrical cavity, precision welded from 304 stainless steel, with an inner diameter of 1200 mm and a height of 1800 mm. The cavity adopts a double-layer water-cooled jacket structure to ensure structural stability and thermal load control under long-term high-temperature operation.

[0026] The core of the induction heating system is a medium-frequency induction power supply with a rated output power of 200 kW and an operating frequency of 2.5 kHz. The copper main induction coil, matched with the medium-frequency induction power supply, has a six-turn spiral structure, an inner diameter of 400 mm, a height of 500 mm, and is circulated with deionized cooling water. Inside the copper main induction coil is a 50 kg capacity water-cooled copper crucible with a wall thickness of 15 mm and a bottom designed as a cone with a 60-degree angle to facilitate the convergence and flow of the molten metal.

[0027] The rotating magnetic field generating unit is integrated into the vacuum melting unit 2 and is used to generate a controllable rotating magnetic field during the melting process to drive the melt 9 in the water-cooled copper crucible to rotate. The rotating magnetic field generating unit is independent of the induction heating system and is powered by a 30-kilowatt medium-frequency power supply with a continuously adjustable output frequency ranging from 1 Hz to 10 Hz. This power supply drives a set of octagonally symmetrically distributed electromagnetic coils, which are mounted around the outer periphery of the copper main induction coil. By precisely adjusting the current phase and frequency of the input coil through a programmable logic controller, a controllable rotating electromagnetic force can be generated in the melt 9 within the water-cooled copper crucible, achieving stepless and stable speed regulation of the melt 9 between 10 and 30 revolutions per minute.

[0028] In practical applications, the phase difference of the electromagnetic coil current is adjusted from 0-180° and the frequency from 1-10Hz via PLC programming, generating a rotating electromagnetic field with a magnetic induction intensity of 0.05-0.2T within the water-cooled copper crucible. This field drives the melt 9 to form a three-dimensional circulation at a speed of 10-30 rpm. The distance between the coil and the water-cooled copper crucible is 50-80mm, and the cooling water flow rate is ≥5L / min to prevent overheating.

[0029] II. Feeding Control System The feeding control system 1 receives signals from the weighing sensor and is linked with the main programmable logic controller (PLC). It can automatically execute graded and batch feeding operations strictly according to the preset quality and timing program. It includes a main feeding bin for initial feeding and a secondary feeding device for replenishing easily burnable elements.

[0030] The main feeding hopper is fixed to the top flange of the vacuum chamber and has a volume of 30 liters. It can be pre-loaded with metal bulk raw materials, excluding easily burnable elements. The bottom of the hopper is equipped with a high-sealing pneumatic gate valve and an integrated weighing sensor with an accuracy of ±10 grams to achieve precise measurement of the feeding amount.

[0031] The secondary feeding device is laterally connected to the center of the vacuum chamber via a vacuum-locked chamber. This five-liter device is specifically designed to replenish easily burnable elements such as aluminum and manganese during the smelting process. The valve system of the secondary feeding device ensures that the main vacuum atmosphere of the smelting chamber is not disrupted during the feeding process.

[0032] III. Air Atomization Unit like Figure 3 As shown, it includes an intermediate ladle 10 connected to the bottom of the water-cooled copper crucible via a flow guiding system, a gas supply system 7, an atomizing tower 8, and a supersonic annular nozzle 6 arranged around the outlet of the intermediate ladle 10. The flow guiding system consists of a vertically mounted flow guide tube and a precision stopper rod mechanism. The flow guide tube is made of high-temperature erosion-resistant graphite-ceramic composite material, with an inner diameter of 25 mm, and is externally encased in a forced-water-cooled copper sleeve. The stopper rod mechanism is driven by a servo motor, with a lifting control accuracy of ±0.5 mm, used to precisely open and close the outlet at the bottom of the water-cooled copper crucible, controlling the start and stop of the molten metal flow.

[0033] The intermediate liner 10 is located at the top of the atomizing tower 8 and is connected to the lower end of the guide pipe via a flange. It has a capacity of ten liters and is made of molybdenum-lanthanum oxide composite material with good high-temperature strength and good compatibility with melt 9. It is externally wrapped with a resistance heating furnace and a heat insulation layer, which can maintain the temperature of melt 9 at a maximum of 1700 degrees Celsius, ensuring that melt 9 has good fluidity before atomization.

[0034] The key component of the atomizing unit 4 is a supersonic annular nozzle 6, such as Figure 4 As shown, it adopts a Laval-type design with six symmetrical nozzles evenly distributed on the annular surface, each with a diameter of 1.2 mm. The nozzle installation position can be finely adjusted to precisely align its axis with the molten metal flow at the outlet of the tundish 10, typically at a distance of 100 mm from the flow, and the spray angle can be adjusted within a range of ±5 degrees to optimize the atomization effect.

[0035] The gas supply system 7 provides a high-purity, high-pressure inert gas medium for atomization. The gas supply system 7 is supplied by a set of high-pressure argon cylinders, with argon purity not less than 99.999%. A gas heater is installed in the pipeline to preheat the atomizing gas to 300 degrees Celsius, reducing the cooling effect on the molten metal droplets. The system pressure is stabilized within the range of 0.5 to 0.7 MPa through a combination of a high-precision pressure reducing valve and a back pressure valve, achieving a control accuracy of ±0.2 MPa.

[0036] The atomizing tower 8 is an upright stainless steel cylinder, eight meters high and three meters in diameter, with its inner surface mirror-polished to reduce powder adhesion.

[0037] IV. Powder Collection Unit Located below the gas atomization unit 4, it includes a cooling system, subsequent processing equipment, and a graded collection system; The cooling system includes a cooling tower and a circulating water cooling jacket surrounding the tower wall, as well as an annular nitrogen curtain air inlet located on the upper part of the cooling tower, which together achieve rapid solidification and cooling of high-temperature powder particles.

[0038] The graded collection system mainly consists of a primary cyclone separator and a secondary bag filter connected in series. The primary cyclone separator efficiently separates and collects the bulk powder with a particle size ranging from 15 to 150 micrometers. Finer sub-15-micrometer powder is carried by the airflow into the secondary bag filter for collection. The end of the graded collection system is connected to six 50-liter dust collection tanks with vacuum-sealed quick-connect interfaces, facilitating powder replacement and transfer under an inert atmosphere.

[0039] Subsequent processing equipment includes a vibrating sieve connected to the outlet of the powder collection tank, used to sieve the powder into target particle size ranges of 15 to 53 micrometers. The sieved powder is then dried, sampled, and finally packaged in a connected vacuum glove box, completely isolating it from air throughout the process.

[0040] V. Vacuum and Atmosphere Control System The vacuum and atmosphere control system 3 includes a vacuum system and an atmosphere control system.

[0041] Used to evacuate and fill the cavities of vacuum melting unit 2 and gas atomization unit 4 with protective gas.

[0042] The vacuum system consists of a three-stage pumping unit comprising a mechanical backing pump, a Roots booster pump, and a molecular pump, connected to the vacuum chamber. This system can achieve an ultimate vacuum of 5 × 10⁻⁶ in the melting chamber. -3 Pa, with a pumping speed of 2,000 liters per second.

[0043] The atmosphere control system includes a mass flow controller for recharging the chamber with high-purity inert gas, with a flow control accuracy of ±1%. Simultaneously, the system integrates an online oxygen analyzer to monitor the oxygen content in the atomizing tower 8 and the collection tank in real time, with a monitoring accuracy of 0.1 ppm.

[0044] Through the precise integration and coordinated control of the above subsystems, the various devices in this embodiment can efficiently and stably implement the complete process of preparing high-entropy alloy powder by combining rotary induction melting with gas atomization. The powder produced has outstanding characteristics such as highly uniform composition, excellent sphericity, and low oxygen content.

[0045] Example 1: This example details the process of preparing high-entropy alloy powder with an atomic percentage of Al8Fe20Co20Ni20Cr20Mo12 using the method of the present invention.

[0046] S1. Raw Material Pretreatment and Batching: Select metal blocks of Al, Fe, Co, Ni, Cr, and Mo with a purity ≥ 99.5%. Grind all raw material surfaces with a grinding wheel until a metallic luster is revealed. Batching is performed according to atomic ratio. Considering the susceptibility of Al to burn-off, an additional 10% compensation is made based on its target content. That is, when actually weighing, the atomic percentage of Al is calculated as 8.8%, and the remaining elements are weighed according to the target proportion to ensure that the total amount is 100%.

[0047] S2. Staged Vacuum Induction Melting and Electromagnetic Stirring: Place the Mo, Cr, Fe, Co, and Ni blocks in sequence into a water-cooled copper crucible. Close the vacuum chamber and start the vacuum system to evacuate to 5 × 10⁻⁶. -2 Pa, then high-purity argon gas was introduced to a pressure of 1.0 × 10⁻⁶ Pa. 5 Pa. Start the induction heating power supply and the medium-frequency rotating magnetic field power supply. Heat to 1380℃ until all the raw materials are melted. Start the rotating magnetic field device to make the melt 9 rotate stably at a speed of 20 rpm, and continue electromagnetic stirring for 25 minutes.

[0048] S3. Refining and Composition Fine-tuning: The compensated Al block is added to melt 9 via a secondary feeding device. Melting continues for 8 minutes to ensure complete melting and incorporation of Al. Subsequently, the temperature of melt 9 is raised to 1620°C and held at this temperature for 20 minutes to perform deep degassing and final homogenization of the composition.

[0049] S4. Gas atomization powder production: Open the stopper at the bottom of the guide tube to introduce the refined alloy melt 9 into the tundish 10, forming a stable liquid flow with a diameter of approximately 5 mm. Simultaneously, turn on the gas source and supply high-purity argon gas at 0.6 MPa to the supersonic annular nozzle 6 at a gas velocity of approximately 300 m / s, breaking up and atomizing the liquid flow. The droplets fall and solidify in the atomization tower 88.

[0050] S5. Powder Collection and Processing: The atomized powder is classified by a cyclone separator, and the fine powder enters the powder collection tank. The collected powder is dried at 80℃ under vacuum for 2 hours, and then sieved using a standard sieve to separate the powder of 15-53μm.

[0051] Characterization of the obtained powder: Scanning electron microscopy showed that the powder had good sphericity, exceeding 92%, with few satellite spheres and a hollow powder rate of approximately 2.1%. Laser particle size analysis showed a D50 of 38 μm. Chemical analysis indicated that the actual composition deviated from the target composition by less than 0.5 at.%, and the oxygen content was below 200 ppm.

[0052] When this powder is used for supersonic flame spraying, the resulting coating is dense with an average hardness of HV0.3620. The corrosion current density in 3.5wt.% NaCl solution is two orders of magnitude lower than that of 304 stainless steel substrate, and the wear resistance is improved by about 2.5 times.

[0053] Example 2: Following the process of Example 1, equiatomic ratio AlCoCrFeNi high-entropy alloy powder was prepared. 8% burn-off compensation was applied to Al during batching. The melting temperature was 1360℃ in step S2 and 1600℃ in step S3. The stirring speed was 15 rpm. The atomizing gas pressure was 0.55 MPa. The resulting 15-53 μm powder had a sphericity ≥90% and a hollow powder ratio <2.5%. It is suitable for laser selective melting additive manufacturing, producing crack-free parts with uniform composition.

[0054] Comparative Example 1: Alloy powder with the same composition as in Example 1 was prepared using a conventional vacuum arc melting ingot casting and inert gas atomization process. Arc melting required five repeated melting cycles to achieve uniformity. After atomization, the powder sphericity was approximately 85%, and the hollow powder rate was close to 5%. Compositional analysis showed approximately 1.2 at.% microsegregation of Mo. The hardness of the sprayed coating with the same parameters was HV0.3, ranging from 540 to 580, showing significant fluctuations, and its corrosion resistance was also lower than that of the coating in Example 1.

[0055] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application.

Claims

1. A rotary induction melting apparatus for high-entropy alloy powder, characterized in that, include: Vacuum melting unit, feeding control system, gas atomization unit, powder collection unit, and vacuum and atmosphere control system; The vacuum melting unit includes a vacuum chamber, a rotating magnetic field generating unit, and an induction heating system disposed within the vacuum chamber; the induction heating system includes a medium-frequency induction power supply and a copper main induction coil, with a water-cooled copper crucible placed inside the copper main induction coil; the rotating magnetic field generating unit is used to generate a rotating magnetic field during the melting process to drive the melt inside the water-cooled copper crucible to rotate. The feeding control system includes a main feeding bin located at the top of the vacuum chamber and a secondary feeding device connected to the middle of the vacuum chamber, for adding raw materials in stages; The gas atomization unit forms a molten metal flow by vertically impacting the melt with inert gas, atomizing the molten metal flow into droplets, and the droplets cool and solidify during flight to form alloy powder. The powder collection unit is located below the gas atomization unit and is used to collect the alloy powder after cooling and solidification. The vacuum and atmosphere control system is used to evacuate and fill the cavities of the vacuum melting unit and the gas atomization unit with protective gas.

2. The apparatus according to claim 1, characterized in that, The rotating magnetic field generating unit includes a medium-frequency power supply and an electromagnetic coil group. The electromagnetic coils in the electromagnetic coil group are symmetrically distributed in an octagonal pattern and driven by the medium-frequency power supply. The electromagnetic coil group is installed around the copper main induction coil. The phase and frequency of the current input to the electromagnetic coil group are adjusted by a programmable logic controller to generate a rotating electromagnetic force in the melt inside the water-cooled copper crucible.

3. The apparatus according to claim 2, characterized in that, The main feeding hopper is fixed to the top flange of the vacuum chamber, and the bottom of the hopper is equipped with a high-sealing pneumatic gate valve and an integrated weighing sensor; the secondary feeding device is laterally connected to the middle of the vacuum chamber through a vacuum locking chamber, and is used to supplement aluminum and manganese elements into the vacuum chamber during the smelting process.

4. The apparatus according to claim 1, characterized in that, The gas atomization unit includes a flow guiding system, an intermediate tundish connected to the bottom of the water-cooled copper crucible via the flow guiding system, a gas supply system, an atomization tower, and a supersonic annular nozzle arranged around the outlet of the intermediate tundish.

5. The apparatus according to claim 4, characterized in that, The flow guiding system includes a vertically installed flow guiding pipe and a stopper rod mechanism. The intermediate package is located at the top of the atomizing tower and is connected to the lower end of the flow guiding pipe via a flange. The supersonic annular nozzle has six symmetrical nozzle holes evenly distributed on its annular surface, and the spray angle can be adjusted. The gas supply system provides an inert gas medium for atomization. The atomizing tower is an upright stainless steel cylinder with a mirror-polished inner surface.

6. The apparatus according to claim 5, characterized in that, The powder collection unit is located below the gas atomization unit and includes a cooling system, subsequent processing equipment, and a graded collection system. The cooling system includes a cooling tower and a circulating water cooling jacket surrounding the tower wall, as well as an annular nitrogen curtain air inlet at the top of the cooling tower, which together achieve rapid solidification and cooling of the alloy powder. The graded collection system consists of a primary cyclone separator and a secondary bag filter connected in series. At the end of the graded collection system, multiple dust collection tanks are connected for replacing and transferring metal powder under an inert atmosphere. Subsequent processing equipment includes a vibrating screen connected to the outlet of the powder collection tank, used to screen the powder into target particle size ranges.

7. A method for preparing high-entropy alloy powder based on the apparatus according to any one of claims 4-6, characterized in that, Includes the following steps: After cleaning the surface of the raw materials, they are batched according to the target high-entropy alloy composition, and a burn-off compensation amount is preset for easily burnable elements. All raw materials except for easily burnable elements are placed in a water-cooled copper crucible in the vacuum melting unit according to their melting points from high to low. Inert gas is introduced under vacuum, and the raw materials are completely melted through an induction heating system to obtain a melt. Simultaneously, a rotating magnetic field is applied during the melting process to drive the melt to rotate continuously for electromagnetic stirring. Easily burnable elements with burn-off compensation are added to the melt through a feeding control system to continue melting. Subsequently, the temperature is raised and held for degassing and composition homogenization. The refined high-entropy alloy melt is introduced into an intermediate ladle through a guide pipe to form a molten metal flow. A supersonic annular nozzle is used to vertically impact the molten metal flow with inert gas, atomizing it into droplets. The droplets cool and solidify during flight to form metal powder. The metal powder is collected and sieved to obtain high-entropy alloy powder within the target particle size range.

8. The preparation method according to claim 7, characterized in that, The purity of the raw material is not less than 99.5 wt.%, and the surface of the raw material is mechanically cleaned to remove oxide scale and impurities; the easily burnable elements include at least one of aluminum and manganese.

9. The preparation method according to claim 7, characterized in that, The process of filling an inert gas in a vacuum environment and then completely melting the raw material through an induction heating system to obtain a melt is as follows: After the vacuum degree is reduced to below 0.1 Pa, inert gas is filled to 0.9 × 10⁻⁶ Pa. 5 -1.1×10 5 Pa; the induction heating temperature is 1350-1400℃, the rotating magnetic field drives the melt to rotate at a speed of 10-30 rpm, and the electromagnetic stirring time is 20-30 minutes.

10. The preparation method according to claim 7, characterized in that, After the collected powder is vacuum dried at 80-120℃ for 1-3 hours, it is sieved to obtain high-entropy alloy powder with a particle size range of 15-53μm.

Images