Apparatus and method for producing niobium-silicon based alloys with high columnar grain content using a multi-layer temperature gradient

Abstract

The application relates to an equipment and method for preparing a niobium-silicon-based alloy with high columnar crystal content by controlling a temperature gradient in multiple layers, and relates to the field of alloy preparation. In order to solve the problems of poor regulation of a temperature field and a strong electromagnetic field, low columnar crystal content and insufficient one-way mechanical performance of the niobium-silicon-based alloy prepared in the prior art, a multi-layer temperature gradient control system is established, a temperature gradient beneficial to the formation of columnar crystals of the niobium-silicon-based alloy is established, and in the process of flowing downward, the protrusions at the solid-liquid interface grow in the direction away from the solid-liquid interface due to the beneficial temperature gradient, and in the growth process, the protrusions continuously discharge solute atoms to the two sides, so that the growth of the protrusions in the vicinity is inhibited, and the niobium-silicon-based alloy with high columnar crystal content is obtained. The pore with gradually changed diameters reduces the loss of the niobium-silicon-based alloy caused by residual melt in the solidification process, and reduces the production cost. The application is used for the preparation of alloys.

Description

TECHNICAL FIELD

[0001] The present application relates to a device and method for preparing a niobium-silicon-based alloy, in particular to a device and method for preparing a niobium-silicon-based alloy with high columnar crystal content by multi-layer control of temperature gradient, and belongs to the technical field of alloy preparation. BACKGROUND

[0002] With the increase of the thrust-to-weight ratio of the aero-engine, the working temperature of the aero-engine turbine blade material has been increasing in recent years, which leads to the fact that the working temperature of most current nickel-based high-temperature alloys is close to the limit, so it is urgent to develop an aero-engine turbine blade material that can work stably at 1300 DEG C to 1450 DEG C.

[0003] The niobium-silicon-based alloy is highly expected due to its high melting point, low density and excellent mechanical properties. Since the unidirectional high strength of columnar crystals is consistent with the unidirectional stress of the aero-engine turbine blade, how to improve the columnar crystal content in the niobium-silicon-based alloy becomes a key factor to promote the development and application of the niobium-silicon-based alloy. The existing technology usually only designs a temperature gradient to control the growth of columnar crystals, so it lacks multi-stage control of the temperature gradient during the solidification process of the niobium-silicon-based alloy, and therefore the columnar crystal content of the prepared niobium-silicon-based alloy is generally low, which is not conducive to the unidirectional mechanical properties of the niobium-silicon-based alloy, thereby limiting the further application and development of the niobium-silicon-based alloy.

[0004] In summary, the temperature field, the regulation of strong electromagnetic field, the low columnar crystal content and the insufficient unidirectional mechanical properties of the niobium-silicon-based alloy prepared by the existing technology are often not in place. SUMMARY

[0005] The purpose of the present application is to solve the problems of temperature field, regulation of strong electromagnetic field, low columnar crystal content and insufficient unidirectional mechanical properties of the niobium-silicon-based alloy prepared by the existing technology. Further, a device and method for preparing a niobium-silicon-based alloy with high columnar crystal content by multi-layer control of temperature gradient are provided.

[0006] The technical scheme of the present application is: a device for preparing a niobium-silicon-based alloy with high columnar crystal content by multi-layer control of temperature gradient comprises a furnace body, and further comprises a strong magnetic field generator, an air tank, an air extraction device, an air charging valve, an air extraction mechanism controller, a cooling crucible and a multi-layer temperature gradient control system,

[0007] The strong magnetic field generator is arranged on the upper end inner side wall and the lower end inner side wall of the furnace body in parallel and opposite directions, the multi-layer temperature gradient control system is installed between the upper part and the lower part of the strong magnetic field generator, and the cooling crucible is located directly below the multi-layer temperature gradient control system;

[0008] The multi-layer temperature gradient control system comprises a primary temperature control unit and a secondary temperature control unit, the primary temperature control unit and the secondary temperature control unit are coaxially arranged from top to bottom and located directly above the cooling crucible, the strong magnetic field generated by the strong magnetic field generator passes through the primary temperature control unit and the secondary temperature control unit made of copper material in sequence, the strong magnetic field lines are consistent with the falling direction of the niobium-silicon based alloy liquid in the primary temperature control unit, the crystal preferred orientation under the strong electromagnetic field is consistent with the direction of the favorable temperature gradient, thereby the top end advantage in the columnar crystal growth process is improved, and the number of columnar crystals of the niobium-silicon based alloy is increased.

[0009] The gas extraction device extends into the furnace body through a pipeline, a gas extraction mechanism controller is installed on the pipeline, a gas charging valve is installed on the gas storage tank and connected with the pipeline, the gas charging valve is on the gas storage tank and controls the cold gas in the gas storage tank to enter the furnace body, and the cold gas in the gas storage tank is charged into the furnace body during the operation of the equipment, and the niobium-silicon based alloy liquid flows in the multi-layer temperature gradient control system to realize heat exchange with the cold gas.

[0010] Further, the device further comprises a gas delivery pipe, which is located at the lower part of the furnace body, one end of the gas delivery pipe is connected with the pipeline, and the other end of the gas delivery pipe is open upward.

[0011] Further, the primary temperature control unit comprises a copper crucible, a primary induction heating coil controller, a primary heating induction coil and a stepped shell, the copper crucible is horizontally installed in the furnace body, the niobium-silicon based alloy raw material is placed in the copper crucible, the primary induction heating coil controller is located outside the furnace body, the primary heating induction coil is wound on the outer sidewall of the copper crucible and then extends out to be connected with the primary induction heating coil controller outside the furnace body, and the stepped shell is located at the lower end of the copper crucible, and a primary hole is arranged at the upper part of the stepped shell.

[0012] Preferably, the copper crucible is formed by buckling left and right open-petal crucibles.

[0013] Further, the primary temperature control unit further comprises a sealing ring and a pulling rod, the pulling rod is horizontally inserted into the sidewall of the furnace body through the sealing ring and then extends into the furnace body to be connected with the open-petal crucible, so as to realize buckling and opening of the left and right open-petal crucibles.

[0014] Further, the secondary temperature control unit comprises a secondary induction heating coil and a secondary induction heating coil controller, the secondary induction heating coil is wound on the lower outer side of the stepped shell and connected with the secondary induction heating coil controller outside the furnace body, and a secondary hole and a tertiary hole are arranged at the middle part and the lower part of the stepped shell respectively; wherein the hole diameters of the primary hole, the secondary hole and the tertiary hole are 1mm, 0.1mm and 0.01mm respectively.

[0015] Furthermore, the secondary temperature control unit also includes a retainer and a retaining rod. One end of the retaining rod is horizontally mounted on the side wall of the furnace body, and the other end of the retaining rod is connected to the outer side of the middle part of the stepped shell through the retainer.

[0016] Furthermore, it also includes multiple fixing bolts and multiple positioning bolts. The outer side of the cooling crucible is connected by multiple vertically arranged fixing bolts, and the lower part of the fixing bolts is connected to the furnace body by multiple positioning bolts.

[0017] This invention also provides a method for preparing an apparatus for preparing niobium-silicon-based alloys with high columnar crystal content using a multilayer controlled temperature gradient, comprising the following steps:

[0018] Step 1: Inspection work;

[0019] Check if the fixing bolts, positioning bolts, and fixing devices are loose. If they are loose, adjust them in time. Check if the pressure gauge reading above the furnace body is normal.

[0020] Step 2: Place the niobium-silicon based alloy raw material;

[0021] Place the niobium-silicon-based alloy raw material into the copper crucible. When placing it, it should be spread evenly, and the height of the niobium-silicon-based alloy raw material should not exceed 8cm. Avoid contact with the strong magnetic field generator. After completing the above actions, close the furnace door.

[0022] Step 3: Perform a vacuum treatment inside the equipment;

[0023] Turn on the evacuation device. When the pressure gauge shows that the vacuum level inside the furnace reaches 0.15MPa, control the evacuation mechanism controller to turn off the evacuation device and open the charging valve at the same time to continuously charge the furnace with oxygen-free cold air. Pay attention to the pressure gauge reading again and keep the vacuum level inside the furnace at 0.02MPa.

[0024] Step 4: Melt the niobium-silicon based alloy raw material;

[0025] Turn on the control button of the strong magnetic field generator on the first-level induction heating controller and the strong magnetic field generator. At the same time, observe the melting process of the niobium-silicon-based alloy raw material through the observation window on the furnace body. After the niobium-silicon-based alloy raw material has completely melted, proceed to the next step.

[0026] Step 5: The molten niobium-silicon alloy molten metal undergoes primary temperature control;

[0027] Move the pull rod outwards to both sides to allow the niobium-silicon alloy molten metal to flow downwards through the gap at the bottom of the copper crucible. At the same time, turn on the secondary induction heating coil controller. After all the niobium-silicon alloy molten metal has passed through the copper crucible, return the pull rod to its original position and turn off the primary induction heating controller.

[0028] Step six: the molten Nb-Si based alloy liquid is subjected to secondary temperature control;

[0029] The solidification of the Nb-Si based alloy liquid in the cooling crucible is observed through the observation window, and the Nb-Si based alloy liquid is completely poured into the cooling crucible;

[0030] The secondary induction heating coil controller is turned off after the Nb-Si based alloy liquid is completely poured and solidified;

[0031] Step seven: the strong magnetic field generator control button and the inflation valve are turned off;

[0032] Step nine: after the Nb-Si based alloy is cooled, the Nb-Si based alloy with high columnar crystal content is taken out, and thus the preparation of the Nb-Si based alloy with high columnar crystal content is completed.

[0033] Further, the Nb-Si based alloy in step nine is Nb-20Si-16Ti alloy.

[0034] Compared with the prior art, the present application has the following effects:

[0035] 1. The present application is provided with a multi-layer temperature gradient control system, which establishes a multi-section temperature gradient conducive to the formation of columnar crystals of the Nb-Si based alloy with a simple structure design. In the process of flowing downward, the protrusions at the solid-liquid interface grow away from the solid-liquid interface due to the favorable temperature gradient, and at the same time, they continuously expel solute atoms to the two sides during the growth process, so that the growth of the nearby protrusions is inhibited, thereby obtaining the Nb-Si based alloy with high columnar crystal content. However, the structure design of the prior art is usually more complex, and at most a single-section temperature gradient is established, so that the columnar crystals gradually lose the advantage of the top end during the growth process, and the content of the Nb-Si based alloy columnar crystals is improved very limitedly.

[0036] 2. The present application designs three holes with different diameters, which gradually decrease from top to bottom. This design enables the Nb-Si based alloy liquid to maintain a multi-section favorable temperature gradient while obtaining a refined structure, thereby further improving the mechanical properties of the alloy. In addition, such a gradual design reduces the loss of the Nb-Si based alloy caused by residual melt during the solidification process, thereby reducing the production cost. However, the prior art usually cannot balance the directional growth of the structure and the refinement of the structure, thereby limiting the improvement of the mechanical properties of the Nb-Si based alloy.

[0037] 3、The present application establishes a heat source at the lower part of the multi-layer temperature gradient control system, and further improves the comprehensive mechanical properties of the obtained niobium-silicon-based alloy by heat treatment on the obtained niobium-silicon-based alloy organization. Due to the genetic characteristics of the organization before and after heat treatment, the niobium-silicon-based alloy after heat treatment still retains a high content of columnar crystals, except that the internal stress of the niobium-silicon-based alloy after heat treatment is eliminated, and the ability to resist deformation and cracking is greatly improved. However, due to the limitation of the structure of the existing equipment, it is not possible to simultaneously heat treat the obtained high columnar crystal content niobium-silicon-based alloy by a single device, thereby increasing the production process and cost. At the same time, due to the low columnar crystal content of the niobium-silicon-based alloy before heat treatment, the improvement after heat treatment is also very limited.

[0038] 4、The present application adds a strong electromagnetic field while controlling the temperature field, which further induces the niobium-silicon-based alloy to grow in the direction away from the solid-liquid interface during solidification. The crystal preferred orientation under the strong electromagnetic field coincides with the direction of the favorable temperature gradient, and the two synergistically improve the top advantage of the protruding organization, thereby greatly improving the content of columnar crystals in the obtained niobium-silicon-based alloy. However, the existing technology usually only controls a single temperature field or electromagnetic field, and does not optimize the structure design to make the electromagnetic field and temperature field synergistically act, thereby the control degree of the niobium-silicon-based alloy organization is very limited. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a schematic diagram of a device for preparing a niobium-silicon-based alloy with high columnar crystal content by a multi-layer controlled temperature gradient;

[0040] Figure 2 is a schematic diagram of a multi-layer temperature gradient control system;

[0041] Figure 3 is a schematic diagram of a strong magnetic field induction line;

[0042] Figure 4 is a niobium-silicon-based alloy organization diagram prepared by the present application;

[0043] Figure 5 is a niobium-silicon-based alloy organization diagram prepared by the existing technology;

[0044] Figure 6 is a unidirectional mechanical property comparison diagram of the niobium-silicon-based alloy prepared by the present application and the niobium-silicon-based alloy prepared by the existing technology;

[0045] Figure 7 is a comparison diagram of the columnar crystal area fraction of the niobium-silicon-based alloy prepared by the present application and the niobium-silicon-based alloy prepared by the existing technology, which is counted by using Image-Pro Plus version 6.0 software. DETAILED DESCRIPTION

[0046] The technical solution of the present application is not limited to the following specific embodiments, but also includes any reasonable combination of the specific embodiments.

[0047] Specific embodiment one: combined Figures 1 to 3 In this embodiment, the furnace body 28 further includes a strong magnetic field generator 8, a gas storage tank 4, a gas extraction device 1, a gas filling valve 3, a gas extraction mechanism controller 2, a cooling crucible 21, and a multi-layer temperature gradient control system,

[0048] The strong magnetic field generator 8 is arranged in parallel and opposite on the upper end and lower end inner side walls of the furnace body 28, the multi-layer temperature gradient control system is arranged between the upper and lower parts of the strong magnetic field generator 8, and the cooling crucible 21 is located directly below the multi-layer temperature gradient control system;

[0049] The multi-layer temperature gradient control system includes a primary temperature control unit and a secondary temperature control unit, which are arranged coaxially from top to bottom and located directly above the cooling crucible 21, the strong magnetic field sensing line 27 emitted by the strong magnetic field generator 8 passes through the primary temperature control unit and the secondary temperature control unit made of copper material in turn, the strong magnetic field sensing line 27 is consistent with the falling direction of the niobium-silicon-based alloy liquid 25 in the primary temperature control unit, and the crystal preferred orientation under the strong electromagnetic field coincides with the direction of the favorable temperature gradient, thereby synergistically improving the top end advantage in the columnar crystal growth process, and further improving the number of columnar crystals of the niobium-silicon-based alloy;

[0050] The gas extraction device 1 extends into the furnace body 28 through a pipeline, the gas extraction mechanism controller 2 is installed on the pipeline, the gas storage tank 4 is installed with the gas filling valve 3 and connected with the pipeline, the gas filling valve 3 is installed on the gas storage tank 4 and controls the cold gas in the gas storage tank 4 to enter the inside of the furnace, the cold gas in the gas storage tank 4 is filled into the inside of the furnace 28 during the operation of the equipment, and the niobium-silicon-based alloy liquid 25 flows in the multi-layer temperature gradient control system to realize heat exchange with the cold gas

[0051] The reason for the above-mentioned problems in the existing equipment is that there is a lack of multi-section control of the niobium-silicon-based alloy solidification structure and regulation of the growth process. The present application is designed to control the temperature gradient in multiple sections to keep the top end advantage of the niobium-silicon-based alloy structure during the solidification process, and to suppress the growth of secondary dendrites by regulating the temperature field and adding a strong electromagnetic field, thereby obtaining a niobium-silicon-based alloy with a significantly increased number of columnar crystals with a simple and unique structure design, effectively solving the problem of low columnar crystal content of the niobium-silicon-based alloy, greatly improving the mechanical properties of the niobium-silicon-based alloy in a single direction, and providing a new path for the further development and application of the niobium-silicon-based alloy in the field of aero-engines.

[0052] The gas tank 4, the gas extraction device 1, the gas filling valve 3 and the gas extraction mechanism controller 2 in the embodiment form a gas control system. After the gas extraction mechanism controller 2 is opened, the gas extraction device 1 starts the gas extraction operation, which aims to extract the gas with high oxygen concentration in the furnace body, so as to prevent the niobium-silicon based alloy raw material 24 from being contaminated in the smelting process. The gas filling valve 3 is on the gas tank 4 and controls the cold gas in the gas tank 4 to enter the furnace body. During the operation of the equipment, the cold gas in the gas tank needs to be filled into the furnace body 28. The niobium-silicon based alloy liquid 25 exchanges heat with the cold gas in the multi-layer temperature gradient control system during the downward flowing.

[0053] The gas stored in the gas tank 4 in the embodiment is argon, which is at room temperature and acts as a protective gas while providing a cooling environment, preventing oxygen from reacting with the niobium-silicon based alloy liquid. In addition, argon as a gas refining agent can remove hydrogen in the niobium-silicon based alloy liquid, thereby improving the purity of the niobium-silicon based alloy, which is beneficial to the improvement of the comprehensive mechanical properties.

[0054] The strong magnetic field generator 8 in the embodiment is controlled by the strong magnetic field generator control button 7. The strong magnetic field generator 8 is divided into two parts and the two parts are parallel. During the operation of the equipment, the strong magnetic field induction line 27 generated by the strong magnetic field generator 8 is consistent with the falling direction of the niobium-silicon based alloy liquid 25. The crystal preferred orientation under the strong electromagnetic field is consistent with the direction of the favorable temperature gradient, thereby synergistically improving the top advantage in the columnar crystal growth process and greatly improving the number of columnar crystals of the niobium-silicon based alloy.

[0055] The strong magnetic field induction line 27 in the embodiment will pass through the copper crucible 13, the cooling crucible 21 and the multi-layer temperature gradient control system. Since they are all made of copper material, they have a shielding effect on the magnetic field generated by the strong magnetic field generator 8, so that no loss occurs. In addition, due to the diamagnetism of copper, the copper material can strengthen the effect of the magnetic field on the niobium-silicon based alloy, which will further improve the induction effect on the solidification process of the niobium-silicon based alloy liquid 25.

[0056] Specific implementation method two: combination Figure 1 The embodiment is described. The embodiment also includes a gas delivery pipe 5. The gas delivery pipe 5 is located at the lower part of the furnace body 28. One end of the gas delivery pipe 5 is connected with the pipeline, and the other end of the gas delivery pipe 5 is open upward. In this way, the gas delivery pipe 5 in the embodiment is located at the lower part of the furnace body 28, and the cold gas enters the furnace body 28 from the bottom to the top through the gas delivery pipe 5. The other components and connection relationships are the same as those in the specific implementation method one.

[0057] Specific implementation method three: combination Figure 1 And Figure 2 The embodiment is described. The primary temperature control unit of the embodiment includes a copper crucible 13, a primary induction heating coil controller 11, a primary heating induction coil 12 and a stepped shell 51,

[0058] The copper crucible 13 is horizontally installed in the furnace body 28, the niobium-silicon base alloy raw material 24 is placed in the copper crucible 13, the primary induction heating coil controller 11 is located outside the furnace body 28, the primary heating induction coil 12 is wound on the outer sidewall of the copper crucible 13 and extends out of the furnace body 28 to be connected with the primary induction heating coil controller 11 outside the furnace body 28, the stepped shell 51 is located at the lower end of the copper crucible 13, and the upper part of the stepped shell 51 is provided with the primary hole 14.

[0059] In this way, the gas filling valve 3 controls the argon gas in the gas storage tank 4 to fill the inside of the furnace body 21, and the argon gas can expel oxygen during the filling process as a protective gas to prevent the niobium-silicon base alloy raw material 16 from being oxidized and contaminated. At the same time, since the gas conveying pipe 15 is located directly above the water-cooled crucible body 5 and the upper end surface of the water-cooled crucible body 5 is a flat surface, the argon gas can also be dissolved into the niobium-silicon base alloy liquid as a gas flux while serving as a protective gas, expelling hydrogen in the niobium-silicon base alloy liquid and improving the purity of the niobium-silicon base alloy ingot. In addition, the gas filling valve 3 is adjusted multiple times during the operation of the equipment, which can slowly and smoothly fill the niobium-silicon base alloy liquid into the ingot former 35, and this process ensures the compactness of the niobium-silicon base alloy ingot structure and the smoothness of its surface. The other components and connection relationships are the same as those in the first or second specific embodiment.

[0060] Specific embodiment four: combination Figure 1 In this embodiment, the copper crucible 13 is a left and right split crucible that is buckled together. In this way, it is convenient to flexibly pull out the two parts to realize the downward flow of the alloy liquid. The other components and connection relationships are the same as those in any one of the first to third specific embodiments.

[0061] Specific embodiment five: combination Figure 1 In this embodiment, the primary temperature control unit further includes a sealing ring 9 and a pulling rod 10. The pulling rod 10 is horizontally inserted into the sidewall of the furnace body 28 through the sealing ring 9 and extends into the furnace body 28 to connect with the split crucible, thereby realizing the buckling and opening of the left and right split crucibles.

[0062] In this embodiment, the copper crucible 13 is located directly below the strong magnetic field generator 8 and contains the niobium-silicon base alloy raw material 24 during the operation of the equipment. The copper crucible 13 is divided into left and right parts and is moved and controlled by the pulling rods 10 on both sides. The sealing ring 9 is located inside the furnace body 28 near the end of the pulling rod 10 and plays a sealing role during the movement of the pulling rod 10. The primary induction heating coil 12 is located around the copper crucible 13 and is controlled by the primary induction heating controller 11. The purpose is to heat the niobium-silicon base alloy raw material 24 as a heat source to melt it. The other components and connection relationships are the same as those in any one of the first to fourth specific embodiments.

[0063] Specific implementation six: combined Figure 1 In this embodiment, the secondary temperature control unit includes a secondary induction heating coil 19 and a secondary induction heating coil controller 20. The secondary induction heating coil 19 is wrapped around the lower outer side of the stepped shell 51 and connected to the secondary induction heating coil controller 20 outside the furnace body 28. The middle and lower parts of the stepped shell 51 are respectively provided with a secondary hole 15 and a tertiary hole 16. The hole diameters of the primary hole 14, the secondary hole 15, and the tertiary hole 16 are 1 mm, 0.1 mm, and 0.01 mm, respectively. The other components and connection relationships are the same as any one of the specific implementations one to five.

[0064] The secondary induction heating coil 19 in this embodiment serves as a heat source for heat treatment, which further improves the comprehensive mechanical properties of the obtained niobium-silicon-based alloy by heat treating the solidified niobium-silicon-based alloy 26 structure. The niobium-silicon-based alloy after heat treatment inherits the characteristics of high columnar crystal content generated under the temperature field and strong electromagnetic field, while eliminating the internal stress of the niobium-silicon-based alloy, greatly improving the ability to resist deformation and cracking.

[0065] The multi-layer temperature gradient control system of this embodiment contains three layers and four regions. The plane containing the primary hole 14 is the first layer, the plane containing the secondary hole 15 is the second layer, and the plane containing the tertiary hole 16 is the third layer. The hole diameters of the primary hole, the secondary hole, and the tertiary hole decrease in turn, which are 1 mm, 0.1 mm, and 0.01 mm, respectively. In the upper part between the second layer and the third layer of the multi-layer temperature gradient control system, a fixer 17 is installed to fix. The fixer 17 is fixedly connected to the furnace body 28 through a fixing rod 18 to ensure the stability of the niobium-silicon-based alloy liquid 25 during the downward flow process. The secondary induction heating coil 19 is installed around the lower part of the third layer of the multi-layer temperature gradient control system, and the secondary induction heating coil 19 is controlled by the secondary induction heating coil controller 20 to ensure the smooth passage of the niobium-silicon-based alloy liquid 25 through the multi-section temperature gradient control system and the heat treatment after solidification.

[0066] The three holes with different diameters in this embodiment: the primary hole 14, the secondary hole 15, and the tertiary hole 16, gradually decrease from top to bottom. The purpose is to refine the structure of the niobium-silicon-based alloy liquid 25 during the final solidification. The finer the structure, the better the performance of the niobium-silicon-based alloy, which will be beneficial to the service life of the material. In addition, the gradual design reduces the loss caused by residual melt during the solidification process of the niobium-silicon-based alloy liquid 25, and improves the service life of the equipment.

[0067] Specific implementation seven: combined Figure 1In this embodiment, the secondary temperature control unit further comprises a fixing device 17 and a fixing rod 18. One end of the fixing rod 18 is horizontally installed on the side wall of the furnace body 28, and the other end of the fixing rod 18 is connected to the outer side of the middle part of the stepped shell 51 through the fixing device 17.

[0068] Specific implementation eight: combination Figure 1 In this embodiment, the cooling crucible 21 is connected to the outer side of the cooling crucible 21 through a plurality of vertically arranged fixing bolts 22, and the lower part of the fixing bolt 22 is connected to the furnace body 28 through a plurality of positioning bolts 23. In this way, the cooling crucible 21 of this embodiment is located directly below the multi-layer temperature gradient control system, and the niobium-silicon-based alloy liquid after heat treatment falls into the cooling crucible 21 for cooling. The cooling crucible 21 is fixedly installed on the furnace body 28 through the fixing bolt 22 and the positioning bolt 23 at both ends, respectively. The niobium-silicon-based alloy with high columnar crystal content is solidified and formed in the cooling crucible 21. The other components and connection relationships are the same as any one of the specific embodiments one to seven.

[0069] Specific implementation nine: combination Figures 1 to 3 In this embodiment, the preparation method comprises the following steps:

[0070] Step one: inspection work;

[0071] Check whether the fixing bolt 22, the positioning bolt 23 and the fixing device 17 are loose, and if they are loose, adjust them in time; check whether the reading of the pressure gauge 6 located above the furnace body 28 is normal;

[0072] Step two: placing the niobium-silicon-based alloy raw material 24;

[0073] Place the niobium-silicon-based alloy raw material 24 in the copper crucible 13. When placing, evenly spread the niobium-silicon-based alloy raw material 24, and the height of the spread niobium-silicon-based alloy raw material 24 should not exceed 8 cm to avoid contact with the strong magnetic field generator 8. After the above actions are completed, close the furnace door;

[0074] Step three: vacuumizing the inside of the equipment;

[0075] Open the air exhaust device 1, and when the pressure gauge 6 shows that the vacuum degree in the furnace reaches 0.15 MPa, control the air exhaust mechanism controller 2 to close the air exhaust device 1, and at the same time, open the gas filling valve 3, so that the cold gas without oxygen continuously fills into the furnace, and pay attention to the reading of the pressure gauge 6 again, and keep the vacuum degree in the furnace at 0.02 MPa;

[0076] Step four: melting the niobium-silicon-based alloy raw material 24;

[0077] Step one: Turn on the primary induction heating controller 11 and the strong magnetic field generator control button 7 on the strong magnetic field generator 8, and observe the melting process of the niobium-silicon based alloy raw material 24 through the observation window 29 on the furnace body 28, and wait until the niobium-silicon based alloy raw material 24 is completely melted before proceeding to the next step;

[0078] Step five: Perform primary temperature control on the melted niobium-silicon based alloy metal liquid 25.

[0079] Move the pull rod 10 outward to the two sides, and allow the niobium-silicon based alloy metal liquid 25 to flow downward through the gap at the lower part of the copper crucible 13, and turn on the secondary induction heating coil controller 19, and wait until the niobium-silicon based alloy metal liquid 25 has completely passed through the copper crucible 13 before returning the pull rod 10 to its original position and turning off the primary induction heating controller 11.

[0080] Step six: Perform secondary temperature control on the melted niobium-silicon based alloy metal liquid 25.

[0081] Observe the solidification of the niobium-silicon based alloy metal liquid 25 in the cooling crucible 21 through the observation window 29, and wait until the niobium-silicon based alloy metal liquid has completely fallen into the cooling crucible 21.

[0082] Turn off the secondary induction heating coil controller 20 after the niobium-silicon based alloy metal liquid 25 has completely fallen into and solidified.

[0083] Step seven: Turn off the strong magnetic field generator control button 7 and the air charging valve 3.

[0084] Step nine: After the niobium-silicon based alloy has cooled, remove the high-columnar-crystal-content niobium-silicon based alloy, and thus the preparation of the high-columnar-crystal-content niobium-silicon based alloy is completed.

[0085] Specific implementation method ten: combined with Figures 1 to 3 In this embodiment, the composition of the niobium-silicon based alloy in step nine is Nb-20Si-16Ti alloy. The other compositions and connection relationships are the same as any one of the specific implementation methods one to seven.

[0086] The alloy system of this embodiment covers niobium-silicon based alloys, and the specific example of the niobium-silicon based alloy composition in the example is Nb-20Si-16Ti alloy.

[0087] Combined with Figures 4 to 7 This embodiment illustrates the effects of the invention. By using Figure 4 and Figure 5By comparison: the Nb-20Si-16Ti alloy prepared by the present application has a large amount of columnar crystal organization, and due to the size of the organization being controlled by the present application, the obtained organization is fine, and the NbSS phase and Nb5Si3 phase are distributed between the slender; while the Nb-20Si-16Ti alloy prepared by the prior art has a certain columnar crystal organization, but the content is significantly less than the former, and due to the absence of phase size control, the Nb-20Si-16Ti alloy prepared by the prior art has a NbSS phase and a Nb5Si3 phase which are relatively thick, which will not be conducive to the improvement of the comprehensive mechanical properties of the alloy. Figure 6 is a comparison chart of the unidirectional mechanical properties of the niobium silicon-based alloy prepared by the present application and the niobium silicon-based alloy prepared by the prior art, the niobium silicon-based alloy prepared by the present application has a high degree of order in the material structure due to the presence of a large amount of columnar crystals, so it exhibits excellent unidirectional mechanical properties, and compared with the niobium silicon-based alloy prepared by the prior art, the organization is fine, there is a fine grain strengthening effect, thereby further improving the unidirectional mechanical properties of the alloy; the niobium silicon-based alloy prepared by the prior art has a limited amount of columnar crystals, and the phase organization is also relatively thick, so the resistance to crack propagation is small, so it exhibits low unidirectional mechanical properties.

[0088] Figure 7 is a comparison chart of the columnar crystal area fraction of the niobium silicon-based alloy prepared by the present application and the niobium silicon-based alloy prepared by the prior art, which is counted by using Image-Pro Plus version 6.0 software, Figure 7 The results further confirm the effect of the present device on the improvement of the columnar crystal content of the niobium silicon-based alloy from the perspective of area fraction statistics, and the improvement effect is as high as 55.8%.

[0089] The above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions 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 application.

Claims

1. An apparatus for producing a niobium-silicon based alloy with a high columnar grain content by means of a multi-layer temperature gradient comprising a furnace body (28), characterised in that: It also includes a strong magnetic field generator (8), a gas tank (4), a gas extraction device (1), a gas filling valve (3), a gas extraction mechanism controller (2), a cooling crucible (21) and a multi-layer temperature gradient control system, The strong magnetic field generator (8) is arranged in parallel and opposite on the upper end and lower end inner side wall of the furnace body (28), the multi-layer temperature gradient control system is arranged between the upper and lower parts of the strong magnetic field generator (8), and the cooling crucible (21) is located directly below the multi-layer temperature gradient control system; The multi-layer temperature gradient control system includes a primary temperature control unit and a secondary temperature control unit, which are coaxially arranged from top to bottom and located directly above the cooling crucible (21), and the strong magnetic field generated by the strong magnetic field generator (8) passes through the primary temperature control unit and the secondary temperature control unit made of copper material in sequence, the falling direction of the niobium-silicon-based alloy liquid (25) in the primary temperature control unit is consistent with the strong magnetic field lines (27), and the crystal preferred orientation under the strong electromagnetic field is consistent with the direction of the favorable temperature gradient, thereby synergistically improving the top end advantage in the columnar crystal growth process and increasing the number of columnar crystals of the niobium-silicon-based alloy. The gas extraction device (1) extends into the furnace body (28) through a pipeline, the gas extraction mechanism controller (2) is installed on the pipeline, the gas tank (4) is provided with the gas filling valve (3) and connected with the pipeline, the gas filling valve (3) is arranged on the gas tank (4) and controls the cold gas in the gas tank (4) to enter the inside of the furnace body, and the cold gas in the gas tank (4) is filled into the inside of the furnace body (28) during the operation of the equipment, and the niobium-silicon-based alloy liquid (25) flows down and exchanges heat with the cold gas in the multi-layer temperature gradient control system.

2. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 1, characterized in that: It also includes a gas delivery pipe (5) located at the lower part of the furnace body (28), one end of the gas delivery pipe (5) is connected with the pipeline, and the other end of the gas delivery pipe (5) is opened upward.

3. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 2, characterized in that: The primary temperature control unit includes a copper crucible (13), a primary induction heating coil controller (11), a primary heating induction coil (12) and a stepped shell (51), The copper crucible (13) is horizontally installed in the furnace body (28), the niobium-silicon-based alloy raw material (24) is placed in the copper crucible (13), the primary induction heating coil controller (11) is located outside the furnace body (28), the primary heating induction coil (12) is wound on the outer side wall of the copper crucible (13) and then extends out to connect with the primary induction heating coil controller (11) outside the furnace body (28), and the stepped shell (51) is located at the lower end of the copper crucible (13), and the upper part of the stepped shell (51) is provided with a primary hole (14).

4. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 3, characterized in that: The copper crucible (13) is formed by buckling left and right open-petal crucibles.

5. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 4, characterized in that: The primary temperature control unit also includes a sealing ring (9) and a pulling rod (10), the pulling rod (10) is horizontally inserted into the side wall of the furnace body (28) through the sealing ring (9) and connected with the open-petal crucible after extending into the furnace body (28), thereby achieving buckling and opening of the left and right open-petal crucibles.

6. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 5, characterized in that: The secondary temperature control unit comprises a secondary induction heating coil (19) and a secondary induction heating coil controller (20), the secondary induction heating coil (19) is wound on the lower outer side of the stepped shell (51) and connected with the secondary induction heating coil controller (20) outside the furnace body (28), and the middle and lower parts of the stepped shell (51) are respectively provided with a secondary hole (15) and a tertiary hole (16); wherein the hole diameters of the primary hole (14), the secondary hole (15) and the tertiary hole (16) are 1mm, 0.1mm and 0.01mm respectively.

7. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by multi-layer temperature gradient control according to claim 6, characterized in that: The secondary temperature control unit further comprises a fixer (17) and a fixing rod (18), one end of the fixing rod (18) is horizontally installed on the side wall of the furnace body (28), and the other end of the fixing rod (18) is connected with the outer side of the middle part of the stepped shell (51) through the fixer (17).

8. The apparatus for preparing niobium-silicon based alloy with high columnar grain content by controlling multi-layer temperature gradient according to claim 7, characterized in that: It further comprises a plurality of fixing bolts (22) and a plurality of positioning bolts (23), the outer side of the cooling crucible (21) is connected through a plurality of vertically arranged fixing bolts (22), and the lower part of the fixing bolt (22) is connected with the furnace body (28) through a plurality of positioning bolts (23).

9. A method for producing a niobium-silicon based alloy with a high columnar grain content using the apparatus of any one of claims 1 to 8, characterized in that: It comprises the following steps: Step one: check the work; Check whether the fixing bolt (22), the positioning bolt (23) and the fixer (17) are loose, and if they are loose, they need to be adjusted in time; check whether the reading of the pressure gauge (6) located above the furnace body (28) is normal; Step two: place the niobium-silicon-based alloy raw material (24); Place the niobium-silicon-based alloy raw material (24) in the copper crucible (13), and evenly lay it when placing, and the height of the laid niobium-silicon-based alloy raw material (24) should not exceed 8cm, so as to avoid contact with the strong magnetic field generator (8), and close the furnace door after the above actions are completed; Step three: perform vacuumizing treatment on the inside of the equipment; Open the air exhaust device (1), and when the pressure gauge (6) shows that the vacuum degree in the furnace reaches 0.15MPa, control the air exhaust mechanism controller (2) to close the air exhaust device (1), at the same time, open the air filling valve (3), so that the cold gas without oxygen continuously fills into the furnace, and pay attention to the reading of the pressure gauge (6) again, and keep the vacuum degree in the furnace at 0.02MPa; Step four: melt the niobium-silicon-based alloy raw material (24); Turn on the primary induction coil heating controller (11) and the strong magnetic field generator control button (7) on the strong magnetic field generator (8), and at the same time, observe the melting process of the niobium-silicon-based alloy raw material (24) through the observation window (29) on the furnace body (28), and after the niobium-silicon-based alloy raw material (24) is completely melted, proceed to the next step; Step five: perform primary temperature control on the melted niobium-silicon-based alloy metal liquid (25); Move the pull rod (10) to the outside of both sides, so that the niobium-silicon-based alloy metal liquid (25) flows downward through the gap at the lower part of the copper crucible (13), and at the same time, open the secondary induction heating coil controller (20), and after the niobium-silicon-based alloy metal liquid (25) passes through the copper crucible (13), return the pull rod (10) to the original position and close the primary induction coil heating controller (11); Step six: perform secondary temperature control on the melted niobium-silicon-based alloy metal liquid (25); Observe the solidification of the molten Nb-Si based alloy (25) in the cooling crucible (21) through the observation window (29), and wait until the molten Nb-Si based alloy falls into the cooling crucible (21) completely; After the molten Nb-Si based alloy (25) falls into the cooling crucible (21) completely and solidifies, turn off the secondary induction heating coil controller (20) ; Step seven: turn off the strong magnetic field generator control button (7) and the inflation valve (3) ; Step nine: after the Nb-Si based alloy cools, take out the Nb-Si based alloy with high columnar crystal content, and thus the preparation of the Nb-Si based alloy with high columnar crystal content is completed.

10. The method of claim 9, wherein: The Nb-Si based alloy in step nine is Nb-20Si-16Ti alloy.

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