Nb-Si-based alloy thin strip controllable melt-spinning equipment based on liquid metal cooling copper roller and thin strip preparation method

Abstract

The invention discloses Nb-Si-based alloy thin strip controllable melt-spinning equipment based on a liquid metal cooling copper roller and a thin strip preparation method, and relates to the technical field of electromagnetic metallurgy. The method solves the problems of silicide coarsening, poor structure uniformity and the like of the Nb-Si-based alloy in the traditional process. A GaIn liquid metal tank is installed on the lower portion in a furnace body, a copper roller is horizontally installed in the GaIn liquid metal tank, a speed control system is installed outside the furnace body, connected with the copper roller and used for controlling the rotating speed of the copper roller, a nozzle is connected with the lower portion of an electromagnetic cold crucible smelting system located in the furnace body, and the nozzle is located over the axis of the copper roller. The tape collecting device is obliquely inserted into the GaIn liquid metal tank; the auxiliary system is installed outside the furnace body and communicates with the interior of the furnace body. The method is suitable for preparing the Nb-Si-based alloy thin strip with high uniformity and ultrahigh temperature resistance, and can be directly used for extreme environment functional components such as high-temperature sealing and sensor substrates.

Description

Technical Field

[0001] The present invention relates to a controllable strip casting device and a method for preparing thin strips, and particularly to a controllable strip casting device and a method for preparing Nb-Si based alloy thin strips based on a liquid metal cooled copper roll, belonging to the technical field of electromagnetic metallurgy. Background Art

[0002] Nb-Si based alloys have broad application prospects in the fields of aerospace, energy, electronics, etc. due to their excellent high-temperature strength, oxidation resistance, and superconducting properties. Traditional preparation methods for Nb-Si based alloys include: melting and casting, powder metallurgy, etc. These preparation methods have disadvantages such as complex processes, high energy consumption, and difficulty in obtaining a uniform microstructure. Moreover, the solidification structure of Nb-Si alloys obtained by traditional casting methods is uneven and the silicides are relatively coarse.

[0003] As a rapid solidification technology, the strip casting method can obtain metal thin strips with uniform thickness and fine microstructure (thin strips refer to strips with a thickness within 0.02 - 0.4 mm), which can effectively improve the microstructure uniformity of Nb-Si based alloys. Traditional strip casting technologies (such as the melt spinning method) usually involve direct contact between the melt and the crucible. This process may introduce impurities or cause composition segregation, and the cooling rate of the water-cooled copper roll is inaccurate. Among them, (1) the risk of material contamination caused by introducing impurities is that the Nb-Si alloy melt (with a melting point usually higher than 1500 °C) is prone to react with oxide crucibles (such as Al2O3, ZrO2) at high temperatures, resulting in oxygen contamination or the formation of non-metallic inclusions, thereby affecting the purity and performance of the thin strips. (2) The influence in terms of composition segregation: High melting point components (such as Nb) may solidify on the crucible wall, resulting in the deviation of the melt composition from the designed ratio (such as the Nb-Si eutectic composition needs to be precisely controlled).

[0004] In order to effectively solve the above problems, an electromagnetic cold crucible technology has been gradually developed. It uses the principle of electromagnetic confinement to prevent the melt from contacting the crucible wall, which can effectively avoid contamination and is a brand-new structure and preparation method. However, for traditional strip casting devices, they cannot be combined with traditional strip casting devices, resulting in the possibility of impurities mixing in during the melt transportation process in traditional strip casting devices. The electromagnetic cold crucible is a "containerless" technology, while strip casting requires directional transportation of the melt. There is an essential discontinuity between the two processes, and additional interface design is required. The high melting point (>1750 °C) and high reactivity of Nb-Si alloys determine that they are prone to react with most container materials. Although electromagnetic confinement can solve crucible contamination, it cannot completely solve the contamination of the transportation channel.

[0005] In summary, the microstructure uniformity of niobium-silicon based alloys prepared under the existing technology is relatively low, and there are problems such as easy contamination of the melt and inaccurate control of the cooling rate in the traditional strip casting process. Summary of the Invention

[0006] The object of the present invention is to solve the problems that the room-temperature fracture toughness of the niobium-silicon-based alloy prepared under the existing technology is relatively low, and the melt in the traditional melt spinning process is vulnerable to contamination and the cooling rate is not accurately controlled. Furthermore, a controllable melt spinning device for Nb-Si-based alloy thin strips based on a liquid metal-cooled copper roller and a method for preparing thin strips are provided.

[0007] The technical solution of the present invention is as follows:

[0008] A controllable melt spinning device for Nb-Si-based alloy thin strips based on a liquid metal-cooled copper roller includes a furnace body, and it further includes an electromagnetic cold crucible melting system, a melt spinning forming system and an auxiliary system; the melt spinning forming system includes a GaIn liquid metal tank, a nozzle, a copper roller, a speed control system and a tape collecting device. The GaIn liquid metal tank is installed at the lower part inside the furnace body. The copper roller is horizontally installed in the GaIn liquid metal tank. The speed control system is installed outside the furnace body and connected to the copper roller to control the rotation speed of the copper roller. The nozzle is connected to the lower part of the electromagnetic cold crucible melting system located inside the furnace body, and the nozzle is located directly above the axis of the copper roller. The tape collecting device is obliquely inserted into the GaIn liquid metal tank, and the tape collecting device faces the tangent direction of the outer circumference of the copper roller; the auxiliary system is installed outside the furnace body and communicated with the inside of the furnace body.

[0009] Furthermore, the electromagnetic cold crucible melting system includes a water-cooled crucible, an induction coil, a feeding device and a connecting device. The upper part of the nozzle is installed on the lower end face of the connecting device. The water-cooled crucible is located on the upper end face of the connecting device. The induction coil is sleeved outside the water-cooled crucible. The feeding device is installed on the furnace body and located directly above the water-cooled crucible.

[0010] Still further, the tape collecting device includes a guide wheel and a coiling wheel, and the guide wheel and the coiling wheel are sequentially installed in the tape collecting groove.

[0011] Preferably, the ratio of the linear velocity of the coiling wheel to the linear velocity of the surface of the copper roller is 0.95 - 0.98.

[0012] Preferably, a spiral water-cooling channel is provided inside the copper roller.

[0013] Furthermore, the auxiliary system includes a power supply, a cooling water circulation system, a vacuum chamber and an argon gas cylinder. The power supply, the cooling water circulation system, the vacuum chamber and the argon gas cylinder are all installed outside the furnace body and communicated with the inside of the furnace body.

[0014] Still further, it further includes a temperature detection system, and the temperature detection system is installed inside the furnace body to perform real-time temperature measurement on the melt in the water-cooled crucible.

[0015] The present invention also provides a method for preparing a thin strip using the controllable melt spinning device for Nb-Si-based alloy thin strips based on a liquid metal-cooled copper roller, and it includes the following steps:

[0016] Step 1: System pre-treatment of the controllable strip casting equipment for Nb-Si based alloy thin strips:

[0017] Step 1.1: Check the connections and seals of each system;

[0018] Step 1.2: Start the cooling water circulation system to ensure that the water flow rate and pressure reach the set values;

[0019] Step 1.3: Evacuate the inside of the furnace body to a vacuum of less than 10 -3 Pa through the vacuum chamber;

[0020] Step 1.4: Fill the furnace body with high-purity argon gas to 0.05 MPa through the argon gas cylinder;

[0021] Step 1.5: Check the liquid level in the GaIn liquid metal bath to ensure that the immersion depth of the copper roller is 10 - 15 mm;

[0022] Step 2: Melting process:

[0023] Step 2.1: Put the proportioned Nb and Si raw materials into the feeding device;

[0024] Step 2.2: Start the power supply, pass a high-frequency current with a working frequency of 50 - 70 kHz into the induction coil, and gradually increase the power to completely melt the raw materials;

[0025] Step 2.3: Maintain the melting state for 10 - 15 minutes to ensure uniform alloy composition;

[0026] Step 3: Strip casting process:

[0027] Step 3.1: Start the rotation of the copper roller through the speed control system and adjust the rotation speed according to the melt temperature:

[0028] Step 3.2: Open the nozzle at the bottom of the water-cooled crucible, control the melt flow rate to 0.5 - 1.0 kg / min, and the melt contacts the rotating copper roller through GaIn liquid metal and quickly solidifies to form a thin strip;

[0029] Step 3.3: Collect the finished thin strip through the strip collecting device;

[0030] Step 4: System shutdown of the controllable strip casting equipment for Nb-Si based alloy thin strips:

[0031] Step 4.1: Stop feeding, close the nozzle at the bottom of the water-cooled crucible, reduce the power of the induction coil, and gradually turn off the power supply;

[0032] Step 4.2: The copper roller continues to rotate for 5 - 10 minutes to ensure complete solidification of the residual melt, stop the rotation of the copper roller, and close the cooling water circulation system;

[0033] Step 42: After the system cools down to room temperature, restore the atmospheric pressure and take out the finished thin strip.

[0034] Furthermore, in Step 12, the water-cooling circulation temperature of the cooling water circulation system is controlled at 18–22 °C, the flow rate is 0.8 m / s, and the flow rate is adjusted in real time to ensure that the surface temperature gradient of the copper roller is <5 °C / mm.

[0035] Furthermore, the relationship between the speed control system and the melt temperature in Step 31 is:

[0036]

[0037] where k is the proportionality constant, obtained by non-linear regression fitting based on experimental data, v0 is the speed of the copper roller, ΔT is the temperature gradient, L is the contact length, and k and μ are the thermal conductivity and viscosity of the liquid metal, respectively.

[0038] The present invention has the following effects compared with the prior art:

[0039] 1. Through the integrated collaborative process of optimizing the melting process parameters (by adjusting the electromagnetic parameters to make the fluid flow more fully, promoting the solute distribution in the molten pool and at the front of the solid-liquid interface to be more uniform, and avoiding local segregation of the alloy) and the design of the Ga-In cooling system (the cooperation between the GaIn liquid metal tank 3 and the copper roller 5 of the present invention, especially the cooling of the melt in the GaIn liquid metal tank through the spiral cooling in the copper roller 5), the present invention is specifically embodied in: providing uniform heat transfer through the GaIn liquid metal medium to avoid local supercooling or overheating, promoting uniform nucleation, and achieving grain refinement through precise control of the rotation speed to realize a controllable cooling rate; preventing air contact through the protective gas environment and the fully enclosed system, and avoiding contact between the melt and the crucible through electromagnetic melting to reduce the oxidation source; the integrated process module design integrates melting and strip casting in one system to reduce intermediate links and solve the problem of long process.

[0040] 2. The present invention innovatively combines the electromagnetic cold crucible technology with the liquid metal cooling strip casting technology. By using GaIn liquid metal as the heat transfer medium, precise control of the microstructure of the Nb-Si-based alloy thin strip is achieved. The precise control is specifically embodied in: (1) Heat transfer uniformity: The GaIn liquid has high thermal conductivity, which can provide a more uniform heat transfer path, reduce the phenomenon of non-uniform local cooling, and promote uniform nucleation; (2) Controllability of the cooling rate: By adjusting the temperature of the GaIn liquid, controlling the initial cooling conditions, and combining with the control of the copper roller speed, precise regulation of the cooling rate is achieved. That is, the present invention solves the problems in the traditional strip casting process such as the melt being easily polluted by the environmental atmosphere and the inaccurate control of the cooling rate.

[0041] 3. The equipment of the present invention not only solves the problem of melt contamination in the traditional belt-swinging process, but also has the following features: (1) electromagnetic suspension smelting: the melt is suspended under the action of the electromagnetic field and does not contact the crucible wall; (2) GaIn liquid metal barrier: GaIn liquid metal and Nb-Si melt are immiscible, forming a physical isolation; (3) closed conveying channel: the channel from the cold crucible to the GaIn liquid metal tank is designed as a fully enclosed structure; (4) protective atmosphere: the entire system is operated in a high-purity argon or vacuum environment. In addition, the present invention also realizes the controllable adjustment of the thin strip structure, especially the adjustment of the thickness of the thin strip, by precisely controlling the rotation speed of the copper roller, which provides a new way for the large-scale preparation of high-performance Nb-Si-based functional materials.

[0042] 4. The present invention realizes the complete isolation transfer of the melt from liquid to solid by constructing a vacuum-sealed electromagnetic induction melting-liquid metal cooling continuous system, completely avoiding the oxidation pollution problem in the intermediate link. The rotation speed of the copper roller is controlled by water cooling to achieve precise control of the microstructure of the Nb-Si-based alloy thin strip. And after electromagnetic induction melting, it is directly sprayed onto the cooling copper roller, eliminating the intermediate ingot remelting step.

[0043] 5. The present invention integrates ultrafast cooling and multi-field control into an integrated process. Because traditional air cooling or copper roller cooling methods are limited by heat transfer dynamics conditions, it is difficult to effectively suppress the coarsening and precipitation of high-melting-point silicides, which seriously damages the high-temperature oxidation resistance and mechanical properties of the material. The present invention breaks through the extensive control mode of material organization in traditional processes. The liquid metal cooling medium used, with its high thermal conductivity and wetting properties, establishes an ultrafast heat transfer channel during the melt solidification stage, limits the diffusion of alloy elements, and significantly improves the strength and toughness matching of the material, providing a solution with both theoretical value and engineering feasibility for the efficient preparation of high-performance intermetallic compound thin strips. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a structural schematic diagram of the belt-throwing forming system;

[0045] Among them, 1. water-cooled crucible, 2. induction coil, 3. GaIn liquid metal tank, 4. nozzle, 5. copper roller, 6. speed control system, 7. belt taking-up device, 8. power supply, 9. cooling water circulation system, 10. vacuum chamber, 11. argon gas bottle, 12. feeding device, 13. connecting device, 14. strip, 15. guide wheel, 16. coil wheel.

[0046] Figure 3 This is a real picture of a thin strip prepared by the equipment and method of the present invention.

[0047] Figure 4The thin strip prepared by the traditional strip casting process is polished, buffed, and etched, and the SEM microstructure is observed using a scanning electron microscope. Figure 5 The thin strip prepared by the present invention is polished, buffed, and etched, and the SEM microstructure is observed using a scanning electron microscope. Specific embodiments

[0048] Specific embodiment 1: In combination with Figures 1 to 2 This embodiment will be described. This embodiment includes a furnace body, and it further includes an electromagnetic cold crucible melting system, a strip casting forming system, and an auxiliary system; the strip casting forming system includes a GaIn liquid metal bath 3, a nozzle 4, a copper roll 5, a speed control system 6, and a tape winding device 7. The GaIn liquid metal bath 3 is installed at the lower part inside the furnace body. The copper roll 5 is horizontally installed inside the GaIn liquid metal bath 3. The speed control system 6 is installed outside the furnace body and is connected to the copper roll 5 to control the rotation speed of the copper roll 5. The nozzle 4 is connected to the lower part of the electromagnetic cold crucible melting system located inside the furnace body, and the nozzle 4 is located directly above the axis of the copper roll 5. The tape winding device 7 is obliquely inserted into the GaIn liquid metal bath 3, and the tape winding device 7 faces the tangent direction of the outer circumference of the copper roll 5; the auxiliary system is installed outside the furnace body and is in communication with the inside of the furnace body.

[0049] The present invention aims to solve the problems that in the conventional process, step-by-step melting and cooling are adopted, and the melt is easily contaminated by the ambient atmosphere during the transfer process. In addition, the traditional air cooling or copper roll cooling methods are limited by heat transfer kinetics conditions and are difficult to effectively inhibit the coarsening and precipitation of high-melting-point silicides, seriously damaging the high-temperature oxidation resistance and mechanical properties of the material. The present invention integrates ultrafast cooling and multi-field regulation (providing a uniform and stable cooling rate through the synergistic effect of precise rotation speed control and GaIn liquid metal heat transfer, which can significantly refine the grains; an induction coil is wound around the outside of the crucible to generate a controllable alternating magnetic field, and the convection driven by the magnetic field will promote the uniform distribution of solutes to avoid the formation of local segregation.) into an integrated process through a vacuum sealing system. Under the action of the speed control system 6, the strip casting rotation speed is precisely controlled to achieve controllable adjustment of the microstructure of the Nb-Si-based alloy thin strip, and amorphous or crystalline thin strips can be selectively prepared.

[0050] In addition, the present invention solves the problems such as melt contamination and inaccurate control of the cooling rate in the traditional strip casting process, improves the product quality and production efficiency, has the characteristics of simple process, low energy consumption, and excellent product performance, and is suitable for the large-scale preparation of high-performance Nb-Si-based functional materials.

[0051] In this embodiment, the bottom of the electromagnetic cold crucible melting system (GaIn liquid metal bath 3) is connected to the strip casting forming system, enabling the molten Nb-Si based alloy to flow into the GaIn liquid metal bath through the nozzle and contact the copper roller. This avoids the problem of the melt contacting the ambient temperature. Among them, the operating temperature of the GaIn liquid metal in this embodiment is 30 - 50 °C.

[0052] Specific Embodiment 2: Figure 1 This embodiment will be described. The electromagnetic cold crucible melting system of this embodiment includes a water-cooled crucible 1, an induction coil 2, a feeding device 12, and a connecting device 13. The upper part of the nozzle 4 is installed on the lower end face of the connecting device 13. The water-cooled crucible 1 is located on the upper end face of the connecting device 13. The induction coil 2 is sleeved outside the water-cooled crucible 1. The feeding device 12 is installed on the furnace body and is located directly above the water-cooled crucible 1.

[0053] With such an arrangement, the induction coil 2 is used to heat the raw materials in the water-cooled crucible 1 to make them into a melt. The feeding device 12 is used to supply raw materials into the water-cooled crucible 1. The connecting device 13 serves as a link between the upper and lower parts. That is, as the installation carrier of the nozzle 4, it connects the nozzle 4 to the water-cooled crucible 1 to achieve the ejection of the melt, and also serves as a support for the installation of the water-cooled crucible 1. The other components and connection relationships are the same as those in Specific Embodiment 1.

[0054] The structure of the connecting device 13 in this embodiment is preferably a double-layer water-cooled flange connection structure.

[0055] Specific Embodiment 3: Figure 2 This embodiment will be described. The tape collecting device 7 of this embodiment includes a guiding wheel 15 and a coiling wheel 16. The guiding wheel 15 and the coiling wheel 16 are sequentially installed in the tape collecting groove. With such an arrangement, it is used to collect and wind the prepared thin tape. The other components and connection relationships are the same as those in Specific Embodiment 1 or 2.

[0056] The structure of the guiding wheel 15 in this embodiment is preferably a cantilever double-support roller, and the structure of the coiling wheel 16 is preferably single-roller passive winding.

[0057] Specific Embodiment 4: Figure 1 This embodiment will be described. The ratio of the linear velocity of the coiling wheel 16 to the linear velocity of the surface of the copper roller 5 in this embodiment is 0.95 - 0.98. With such an arrangement, it is used to compensate for the thermal shrinkage difference of the Nb-Si alloy thin tape from high temperature (copper roller cooling zone) to room temperature (coiling zone) to ensure dimensional consistency. The other components and connection relationships are the same as those in Specific Embodiments 1, 2, or 3.

[0058] Specific Embodiment 5: Figure 1 This embodiment will be described. A spiral water-cooling channel is provided inside the copper roller 5 in this embodiment.

[0059] Set in this way to improve the cooling efficiency. Other components and connection relationships are the same as those in the first, second, third, or fourth specific implementation manners.

[0060] Specific implementation manner six: Figure 1 In this implementation manner, the auxiliary system includes a power supply 8, a cooling water circulation system 9, a vacuum chamber 10, and an argon gas cylinder 11. The power supply 8, the cooling water circulation system 9, the vacuum chamber 10, and the argon gas cylinder 11 are all installed outside the furnace body and communicate with the inside of the furnace body.

[0061] Set in this way, the protective gas is high-purity argon with a pressure of 0.05 MPa, which is used to control and achieve anti-oxidation and anti-pollution control throughout the process. Other components and connection relationships are the same as any one of the first to fifth specific implementation manners.

[0062] Specific implementation manner seven: Figure 1 In this implementation manner, it further includes a temperature detection system. The temperature detection system is installed inside the furnace body 1 to measure the temperature of the melt in the water-cooled crucible 1 in real time.

[0063] Set in this way, the temperature monitoring system includes an infrared thermometer, which is used to monitor the melt temperature in real time. The temperature measurement range is 1000 - 2000 °C, and the accuracy is ±10 °C. Other components and connection relationships are the same as any one of the first to sixth specific implementation manners.

[0064] Specific implementation manner eight: Figures 1 to 2 In this implementation manner, the method for preparing the thin strip includes the following steps:

[0065] Step one: System pre-treatment of the Nb-Si based alloy thin strip controllable spin casting equipment:

[0066] Step 1.1: Check the connection and sealing conditions of each system;

[0067] Step 1.2: Start the cooling water circulation system 9 to ensure that the water flow rate and pressure reach the set values;

[0068] Step 1.3: Evacuate the inside of the furnace body to below 10 -3 Pa through the vacuum chamber 10;

[0069] Step 1.4: Fill the furnace body with high-purity argon to 0.05 MPa through the argon gas cylinder 11;

[0070] Step 1.5: Check the liquid level in the GaIn liquid metal bath 3 to ensure that the immersion depth of the copper roller 5 is 10 - 15 mm;

[0071] Step two: Melting process:

[0072] Step 2-1: Put the proportioned Nb and Si raw materials into the feeding device 12;

[0073] Step 2-2: Start the power supply 8, pass high-frequency current with a working frequency of 50 - 70 kHz into the induction coil 2, and gradually increase the power to completely melt the raw materials;

[0074] Step 2-3: Maintain the melting state for 10 - 15 minutes to ensure the uniformity of the alloy composition;

[0075] Step 3: The strip casting process:

[0076] Step 3-1: Start the copper roller 5 to rotate through the speed control system 6, and adjust to the corresponding rotation speed according to the melt temperature:

[0077] Step 3-2: Open the nozzle 4 at the bottom of the water-cooled crucible 1, control the melt flow rate to be 0.5 - 1.0 kg / min, and the melt quickly solidifies and forms a thin strip after contacting the rotating copper roller 5 through the GaIn liquid metal;

[0078] Step 3-3: Collect the finished thin strip through the strip collecting device 7;

[0079] Step 4: Shut down the system of the Nb-Si-based alloy thin strip controllable strip casting equipment:

[0080] Step 4-1: Stop feeding, close the nozzle 4 at the bottom of the water-cooled crucible 1, reduce the power of the power supply for the induction coil 2, and gradually turn off the power supply;

[0081] Step 4-2: The copper roller 5 continues to rotate for 5 - 10 minutes to ensure that the residual melt is completely solidified, stop the rotation of the copper roller 5, and close the cooling water circulation system 9;

[0082] Step 4-2: After the system cools down to room temperature, restore the atmospheric pressure and take out the finished thin strip.

[0083] By adjusting the rotation speed of the water-cooled copper roller, the grain size of the obtained thin strip can be controlled.

[0084] The other compositions and connection relationships are the same as any one of the specific embodiments 1 to 7.

[0085] Specific embodiment 9: Combining Figures 1 to 2 To illustrate this embodiment, in step 1-2 of this embodiment, the water-cooling circulation temperature of the cooling water circulation system 9 is controlled at 18 - 22 °C, the flow rate is 0.8 m / s, and the flow rate is adjusted in real time to ensure that the surface temperature gradient of the copper roller < 5 °C / mm.

[0086] With such settings, it is used to achieve efficient cooling and thermal stability. The other compositions and connection relationships are the same as any one of the specific embodiments 1 to 8.

[0087] Specific embodiment 10: CombiningFigures 1 to 2 Regarding this embodiment, the relationship between the medium speed control system 6 and the melt temperature in Step 3 of this embodiment is as follows:

[0088]

[0089] Among them, k is the proportionality constant, which is obtained by non-linear regression fitting based on experimental data, v0 is the speed of the copper roller, ΔT is the temperature gradient, L is the contact length, and k and μ are the thermal conductivity and viscosity of the liquid metal respectively.

[0090] With such a setting, the speed control system includes a high-precision servo motor, which can control the rotation speed of the copper roller. The other components and connection relationships are the same as any one of the specific embodiments 1 to 9.

[0091] Combined with Figures 1 to 2 The working principle of the present invention is described as follows: A controllable strip casting device for Nb-Si based alloy thin strips based on liquid metal cooling of copper rollers in this embodiment includes the following steps:

[0092] 1. System pretreatment:

[0093] Check the connection and sealing of each system, start the cooling water circulation system, and ensure that the water flow and pressure reach the set values. Evacuate to below 10^ -3 Pa, fill with high-purity argon to 0.05 MPa, check the liquid level in the GaIn liquid metal tank, and ensure that the immersion depth of the copper roller is appropriate

[0094] 2. Melting process:

[0095] Put the proportioned Nb and Si raw materials into the feeding system, start the power supply system, pass high-frequency current into the induction coil, gradually increase the power, completely melt the raw materials, and maintain the melting state for 10 - 15 minutes to ensure uniform alloy composition.

[0096] 3. Strip casting process:

[0097] Start the rotation of the copper roller, adjust the speed according to the melt temperature: Open the nozzle at the bottom of the crucible, control the melt flow rate to be 0.5 - 1.0 kg / min, and the melt quickly solidifies and forms a thin strip after contacting the rotating copper roller through GaIn liquid metal. Collect the finished thin strip through the strip collecting device.

[0098] 4. System shutdown:

[0099] Stop feeding, close the nozzle at the bottom of the crucible, reduce the power of the induction power supply, and gradually turn off the power. Continue to rotate the copper roller for 5 - 10 minutes to ensure that the residual melt is completely solidified, stop the rotation of the copper roller, and close the cooling water circulation system. After the system cools to room temperature, restore the atmospheric pressure and take out the finished thin strip.

[0100] The ribbons prepared by the traditional melt spinning process and the present invention are ground, polished and etched, and the SEM microstructure is observed by using a scanning electron microscope. The results are as Figure 4 , Figure 5 shown.

[0101] It can be seen from the cross-section of the solidification microstructure of the alloy that under the conditions of multi-field regulation and rapid solidification of the present invention, the grain size of the alloy is significantly reduced, the refinement effect of the microstructure is remarkable, the silicides are dispersed, and the alloy has a high solid solubility. It can be obtained from the above that the melt spinning process implemented by the present invention can significantly improve the tissue uniformity of the Nb-Si based superalloy.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A controllable strip casting device for Nb-Si based alloy thin strips based on a liquid metal cooled copper roll, which comprises a furnace body, and is characterized in that: It also includes an electromagnetic cold crucible melting system, a strip casting forming system and an auxiliary system; The strip casting forming system includes a GaIn liquid metal bath (3), a nozzle (4), a copper roller (5), a speed control system (6) and a tape collecting device (7). The GaIn liquid metal bath (3) is installed at the lower part inside the furnace body. The copper roller (5) is horizontally installed inside the GaIn liquid metal bath (3). The speed control system (6) is installed outside the furnace body and connected to the copper roller (5) to control the rotation speed of the copper roller (5). The nozzle (4) is connected to the lower part of the electromagnetic cold crucible melting system located inside the furnace body, and the nozzle (4) is directly above the axis of the copper roller (5). The tape collecting device (7) is obliquely inserted into the GaIn liquid metal bath (3), and the tape collecting device (7) faces the tangent direction of the outer circumference of the copper roller (5). The auxiliary system is installed outside the furnace body and communicates with the inside of the furnace body.

2. The controllable strip casting equipment for Nb-Si based alloy thin strip based on a liquid metal cooled copper roll according to claim 1, characterized in that: The electromagnetic cold crucible melting system includes a water-cooled crucible (1), an induction coil (2), a feeding device (12) and a connecting device (13). The upper part of the nozzle (4) is installed on the lower end face of the connecting device (13). The water-cooled crucible (1) is located on the upper end face of the connecting device (13). The induction coil (2) is sleeved outside the water-cooled crucible (1). The feeding device (12) is installed on the furnace body and is directly above the water-cooled crucible (1).

3. A controllable strip casting device for Nb-Si based alloy thin strip based on a liquid metal cooled copper roll according to claim 2, characterized in that: The tape collecting device (7) includes a guide wheel (15) and a coil wheel (16). The guide wheel (15) and the coil wheel (16) are sequentially installed in the tape collecting groove.

4. A controllable spinning device for Nb-Si-based alloy thin strips based on a liquid metal-cooled copper roll according to claim 3, characterized in that: The ratio of the linear velocity of the coil wheel (16) to the linear velocity of the surface of the copper roller (5) is 0.95 - 0.

98.

5. A controllable strip casting device for Nb-Si based alloy thin strips based on a liquid metal cooled copper roll according to claim 4, characterized in that: The copper roller (5) is provided with a spiral water-cooling channel.

6. The controllable strip casting device for Nb-Si-based alloy thin strip based on a liquid metal cooled copper roll according to claim 5, characterized in that: The auxiliary system includes a power supply (8), a cooling water circulation system (9), a vacuum chamber (10) and an argon gas cylinder (11). The power supply (8), the cooling water circulation system (9), the vacuum chamber (10) and the argon gas cylinder (11) are all installed outside the furnace body and communicate with the inside of the furnace body.

7. A controllable strip casting device for Nb-Si based alloy thin strips based on a liquid metal cooled copper roll according to claim 1, characterized in that: It also includes a temperature detection system. The temperature detection system is installed inside the furnace body (1) to measure the temperature of the melt in the water-cooled crucible (1) in real time.

8. A method for preparing a thin strip of an Nb-Si-based alloy by using a controllable spinning device for a thin strip of an Nb-Si-based alloy based on a liquid metal-cooled copper roll according to any one of claims 1 to 7, characterized in that: It includes the following steps: Step 1: System pretreatment of the Nb-Si based alloy thin strip controllable strip casting equipment: Step 1.1: Check the connection and sealing conditions of each system; Step 1.2: Start the cooling water circulation system (9) to ensure that the water flow rate and pressure reach the set values; Step 1-3: Evacuate the interior of the furnace body to below 10 -3 Pa through the vacuum chamber (10); Step 1.4: Fill the furnace body with high-purity argon gas through the argon gas cylinder (11) to 0.05 MPa; Step 1.5: Check the liquid level in the GaIn liquid metal bath (3) to ensure that the immersion depth of the copper roller (5) is 10 - 15 mm; Step 2: Melting process: Step 2.1: Put the proportioned Nb and Si raw materials into the feeding device (12); Step 2.2: Start the power supply (8), pass a high-frequency current with a working frequency of 50 - 70 kHz into the induction coil (2), and gradually increase the power to completely melt the raw materials; Step 2.3: Keep the melting state for 10 - 15 minutes to ensure the uniformity of the alloy composition; Step 3: Strip casting process: Step 3.1: Start the rotation of the copper roller (5) through the speed control system (6) and adjust the rotation speed according to the melt temperature: Step 3-2: Open the nozzle (4) at the bottom of the water-cooled crucible (1), control the melt flow rate to be 0.5 - 1.0 kg / min, and the melt quickly solidifies and forms a thin strip after contacting the rotating copper roller (5) through GaIn liquid metal; Step 3-3: Collect the finished thin strip through the strip collecting device (7); Step 4: Shut down the system of the Nb-Si based alloy thin strip controllable spinning equipment: Step 4-1: Stop feeding, close the nozzle (4) at the bottom of the water-cooled crucible (1), reduce the power of the induction coil (2), and gradually turn off the power supply; Step 4-2: The copper roller (5) continues to rotate for 5 - 10 minutes to ensure that the residual melt is completely solidified, stop the rotation of the copper roller (5), and close the cooling water circulation system (9); Step 4-2: After the system cools down to room temperature, restore the atmospheric pressure and take out the finished thin strip.

9. The method for preparing a thin strip according to claim 8, characterized in that: In Step 1-2, the water-cooling circulation temperature of the cooling water circulation system (9) is controlled at 18–22°C, the flow rate is 0.8 m / s, and the flow rate is adjusted in real time to ensure that the surface temperature gradient of the copper roller is <5°C / mm.

10. The method for preparing a thin strip according to claim 9, characterized in that: In Step 3-1, the relationship between the speed control system (6) and the melt temperature is: where k is the proportionality constant, obtained by non-linear regression fitting based on experimental data, v0 is the speed of the copper roller, ΔT is the temperature gradient, L is the contact length, and k and μ are the thermal conductivity and viscosity of the liquid metal respectively.

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