Method and device for preparing metal materials by multi-magnetic field assisted directional solidification

Abstract

The present invention discloses a method and device for preparing metal materials by multi-magnetic field assisted directional solidification, including a smelting device, a magnetic field generating device, a vacuum cavity, a cooling tank, a temperature measuring system, a pulling device, a vacuum system and an experimental atmosphere source; the cooling tank is arranged at the bottom of the vacuum cavity, the smelting device is arranged in the vacuum cavity, the magnetic field generating device is arranged in the cooling tank, the vacuum system is connected to the inner cavity of the vacuum cavity, and is used to evacuate the vacuum cavity, the experimental atmosphere source is connected to the inner cavity of the vacuum cavity, and is used to fill the experimental atmosphere into the vacuum cavity after evacuation; the temperature measuring system is used to monitor the upper surface temperature of the sample in the vacuum cavity; the present invention regulates the pulling speed, magnetic field strength and magnetic field type of directional solidification during the directional solidification of the metal melt, and can design the material structure according to the requirements of different performances of different sections of the material in complex application environments. The prepared material has gradient organization and performance along the radial direction.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material preparation, and in particular to a method and a device for preparing metal materials by multi-magnetic field assisted directional solidification. Background Art

[0002] Applying a magnetic field to the metal melt during the solidification process can effectively improve the structure and properties of the metal material by changing the convection inside the melt and controlling its mass and heat transfer behavior. At present, the main types of external magnetic fields include steady magnetic field and traveling magnetic field. The convection behavior in the melt shows great differences under the action of different magnetic fields. Under the action of the transverse steady magnetic field, the solute will show a segregation behavior toward the crucible wall, which is widely used in the field of metal impurity removal; the longitudinal steady magnetic field can effectively regulate the crystal orientation characteristics of the alloy material; the traveling magnetic field can promote convection inside the melt to reduce defects such as shrinkage cavities and segregation.

[0003] In directional solidification technology, the alloy melt grows against the temperature gradient, and the crystal solidifies in the opposite direction of the heat flow. This technology can obtain columnar crystals or single crystal structures with the same orientation, thereby improving the application performance of the material. Compared with traditional solidification methods, directional solidification technology has broader application prospects in the preparation of high-performance alloys. However, it has certain limitations in the research and development and manufacturing of new functional metal materials due to the limitations of technical conditions such as the directional solidification pulling speed. The external magnetic field directional solidification technology proposed in recent years combines the advantages of magnetic field regulation and directional solidification. Chinese patent CN108655375A proposes a method for preparing gradient materials by directional solidification under axial steady magnetic field conditions, and prepares functional gradient materials with gradient properties by changing the magnetic induction intensity of the external magnetic field; Chinese patent CN104625022A proposes a method for removing impurities from metal materials by applying a transverse magnetic field during directional solidification. The thermal electromagnetic flow formed in the metal melt is used to make the inclusions concentrate on one side of the crucible; Chinese patent CN102071469B proposes a device for applying a traveling wave magnetic field during directional solidification, which can refine the dendrite structure of the material by changing the intensity and frequency of the traveling wave magnetic field. The above existing technologies mainly use a single magnetic field to regulate the organizational properties of metal materials, and the solidification mechanism of metal materials under multiple magnetic field conditions and the design of the preparation device have not yet been involved. In the design of the external magnetic field directional solidification device, the volume of the magnetic field generator is very large and the types of external magnetic fields are relatively small. At the same time, in the preparation of new metal materials, the materials prepared by using a single external magnetic field have small gradient differences along the directional growth direction, which makes it difficult to meet the differentiated performance requirements of each section of the material in complex application environments.

[0004] In summary, providing a method and device for preparing metal materials by multi-magnetic field assisted directional solidification is an issue that needs to be urgently addressed by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for preparing metal materials by multi-magnetic field assisted directional solidification, so as to solve the problems existing in the above-mentioned prior art. It can apply a single magnetic field, a multi-level magnetic field and a composite magnetic field during the directional solidification process of the material, and can design the material structure according to the requirements of complex application environments for differentiated performance of different sections of the material, thereby providing a way to design and develop new metal materials.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a method for preparing a metal material by multi-magnetic field assisted directional solidification, comprising the following steps:

[0008] (1) Select high-purity bulk metal raw materials and configure the required metal materials in proportion; process the materials into suitable sizes, load them into a ceramic crucible, and connect the crucible to a pull rod;

[0009] (2) Installing four magnetic field generators in the cooling tank corresponding to the moving device; adjusting the working position of the magnetic field generator by means of the magnetic field lifting assembly and the magnetic field translation assembly;

[0010] (3) evacuating the vacuum chamber; melting the alloy material into a metal melt to achieve directional growth of the alloy during the directional pulling process of the pulling rod;

[0011] (4) First solidification stage: starting the pulling device to pull the molten metal into the Ga-In-Sn liquid metal cooling medium in the cooling tank for directional solidification; the molten metal solidifies under the action of a first external magnetic field, and the magnetic field mainly acts on the solid-liquid interface of the material; the first external magnetic field can be a transverse steady magnetic field, a longitudinal steady magnetic field, a transverse traveling wave magnetic field, a longitudinal traveling wave magnetic field, or a composite magnetic field formed by any two of the four magnetic fields;

[0012] (5) Second solidification stage: when the material is immersed in the Ga-In-Sn liquid metal cooling medium at a set distance, the position of the magnetic field generator is adjusted so that the material solidifies under the action of a second external magnetic field; the second external magnetic field has a different type, intensity or frequency from the first external magnetic field;

[0013] (6) nth solidification stage: when the material is immersed in the Ga-In-Sn liquid metal cooling medium at a set distance, the position of the magnetic field generator is adjusted so that the material solidifies under the action of the nth external magnetic field;

[0014] (7) After the metal material is cooled to room temperature, it is taken out and the metal material has a solidified structure with multiple sections of different directional growth characteristics along the radial direction.

[0015] The present invention also provides a device for preparing metal materials by multi-magnetic field assisted directional solidification, which is applied to the above-mentioned method for preparing metal materials by multi-magnetic field assisted directional solidification, and comprises a smelting device, a magnetic field generating device, a vacuum chamber, a cooling tank, a temperature measuring system, a pulling device, a vacuum pumping system and an experimental atmosphere source;

[0016] The cooling tank is arranged at the bottom of the vacuum cavity, the smelting device is arranged in the vacuum cavity, the magnetic field generating device is arranged in the cooling tank, the vacuum pumping system is connected to the inner cavity of the vacuum cavity, and is used to evacuate the vacuum cavity, and the experimental atmosphere source is connected to the inner cavity of the vacuum cavity, and is used to fill the vacuum cavity after evacuation with the experimental atmosphere; the temperature measuring system is used to monitor the upper surface temperature of the sample in the vacuum cavity;

[0017] The smelting device comprises an induction coil, a graphite sleeve and a crucible; the graphite sleeve is cylindrical graphite, the induction coil is wound around the outside of the graphite sleeve, the crucible is arranged in the graphite sleeve, the bottom of the crucible is connected to the pulling device, and the pulling device controls the crucible to move vertically in the graphite sleeve; an annular graphite pad is arranged at the bottom of the graphite sleeve, a ceramic pad is arranged at the bottom of the graphite pad, and a graphite felt is arranged between the ceramic pad and the top plate of the cooling tank at the bottom thereof;

[0018] The magnetic field generating device comprises a magnetic field generator, a heat protection sleeve, a magnetic field control device and a power supply device; the magnetic field generator comprises a longitudinal steady magnetic field generator, a transverse steady magnetic field generator, a longitudinal traveling wave magnetic field generator and a transverse traveling wave magnetic field generator;

[0019] The longitudinal steady magnetic field generator is composed of an annular permanent magnet and a heat protection sleeve sleeved outside the annular permanent magnet, and can generate a steady magnetic field parallel to the directional solidification direction;

[0020] The transverse constant magnetic field generator comprises two square permanent magnets placed opposite to each other and a heat protection sleeve sleeved outside the square permanent magnets, wherein the N poles and S poles of the two square permanent magnets are placed opposite to each other, and can provide a transverse constant magnetic field;

[0021] The longitudinal traveling wave magnetic field generator is composed of a longitudinally distributed copper coil and a heat protection sleeve sleeved outside the copper coil, and can generate a traveling wave magnetic field parallel to the directional solidification direction;

[0022] The transverse traveling wave magnetic field generator comprises two rectangular coils placed opposite to each other and a heat protection sleeve sleeved outside the rectangular coils, and is capable of generating a transverse traveling wave magnetic field;

[0023] The magnetic field control device includes a magnetic field lifting component and a magnetic field translation component, wherein the magnetic field lifting component is composed of a lifting rod and a servo motor 1, which is used to control the lifting and lowering of the annular permanent magnet and the copper coil in the cooling tank cavity; the magnetic field translation component includes a translation support rod and a servo motor 2, which is used to control the horizontal position of the square permanent magnet and the rectangular coil;

[0024] The power supply device is used to supply power to the internal coil of the magnetic field generating device.

[0025] Preferably, the vacuum pumping system comprises a mechanical pump and a molecular pump, the mechanical pump is connected to the molecular pump, and the molecular pump pipeline is connected to the cavity of the vacuum cavity.

[0026] Preferably, the induction coil is a copper coil with circulating cooling water flowing inside.

[0027] Preferably, the pulling device comprises a pulling motor and a pulling rod, the bottom of the pulling rod is connected to the pulling motor, and the top of the pulling rod is connected to the crucible via a molybdenum alloy adapter, and the crucible is a cylindrical corundum crucible with a flat bottom.

[0028] Preferably, the heat protection sleeve is an alumina ceramic sleeve.

[0029] Preferably, the cooling tank comprises a cylindrical demagnetized stainless steel tank body, a Ga-In-Sn liquid metal cooling medium and a copper tube with circulating cooling water, the Ga-In-Sn liquid metal cooling medium is installed in the tank body, and the copper tube is located in the Ga-In-Sn liquid metal cooling medium in the tank body.

[0030] Preferably, the power supply device includes an electrode flange and a power supply; the electrode flange is installed on the side wall of the vacuum chamber, and the electrode flange connects the external power supply with the internal longitudinal traveling wave magnetic field generator and transverse traveling wave magnetic field generator through a wire.

[0031] Preferably, the side walls of the vacuum cavity and the cooling tank are both double-layer water-cooled structures with water-cooled interlayers inside, and the water-cooled interlayers of the vacuum cavity and the cooling tank are connected to a water cooler through pipelines.

[0032] Preferably, the temperature measuring device is an infrared thermometer; the infrared thermometer is installed on the top of the vacuum chamber.

[0033] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0034] 1. The metal material preparation method provided by the present invention regulates the directional solidification pulling speed, magnetic field strength and magnetic field generator type during the directional solidification of the metal melt, and can design the material structure according to the requirements of different performances of different sections of the material in complex application environments. The prepared material has gradient organization and performance along the radial direction.

[0035] 2. The magnetic field generating device of the directional solidification apparatus provided by the present invention is directly switched in the cavity, which can meet the directional solidification of metal materials in a single magnetic field and a composite magnetic field, simplifying the experimental operation process while greatly reducing the cost of experimental equipment.

[0036] 3. The magnetic field generating device of the present invention adopts liquid metal cooling, and multi-layer heat insulation treatment of graphite pads, ceramic pads, and graphite felt, so as to realize the stable operation of the magnetic field generator in a high temperature and high frequency magnetic field environment.

[0037] 4. The distance between all magnetic field generating devices and samples in the present invention is very small, which effectively reduces the attenuation of magnetic field with distance, reduces energy consumption and experimental costs. It is a more low-carbon and environmentally friendly method for preparing new high-temperature metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the method for preparing metal materials by multi-magnetic field assisted directional solidification in the present invention;

[0040] Figure 2 A schematic diagram of the structure of the device for preparing metal materials by multi-magnetic field assisted directional solidification according to the present invention;

[0041] Figure 3 for Figure 2 Horizontal schematic diagram of the medium magnetic field generating device;

[0042] Figure 4 for Figure 2 A vertical schematic diagram of the medium magnetic field generating device;

[0043] Figure 5 It is a structural schematic diagram of a longitudinal steady magnetic field generator;

[0044] Figure 6 It is a structural schematic diagram of a transverse steady magnetic field generator;

[0045] Figure 7 It is a structural schematic diagram of a longitudinal traveling wave magnetic field generator;

[0046] Figure 8 It is a structural schematic diagram of a transverse traveling wave magnetic field generator;

[0047] In the figure: 1-induction coil; 2-graphite sleeve; 3-crucible; 4-ceramic pad; 5-magnetic field generator; 6-mechanical pump; 7-molecular pump; 8-experimental atmosphere source; 9-vacuum chamber; 10-water chiller; 11-infrared thermometer; 12-pulling device; 13-annular permanent magnet; 14-square permanent magnet; 15-copper coil; 16-rectangular coil; 17-servo motor 2; 18-translational support rod; 19-Ga-In-Sn liquid metal cooling medium; 20-pulling rod; 21-servo motor 1; 22-lifting rod; 23-cooling tank; 24-sample; 25-thermal protection sleeve. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The purpose of the present invention is to provide a device and method for preparing metal materials by multi-magnetic field assisted directional solidification, so as to solve the problems existing in the prior art.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] This embodiment provides a method for preparing metal materials by multi-magnetic field assisted directional solidification, such as Figure 1 As shown, the following steps are included:

[0052] (1) Select high-purity bulk metal raw materials and configure the required metal materials in proportion; process the materials into suitable sizes and load them into the ceramic crucible 3 and connect the crucible 3 to the pull rod 20;

[0053] (2) four magnetic field generators 5 are installed in the cooling tank 23 corresponding to the mobile device; the working position of the magnetic field generator 5 can be adjusted by the magnetic field lifting assembly and the magnetic field translation assembly;

[0054] (3) evacuating the vacuum chamber 9; melting the alloy material into a metal melt to achieve directional growth of the alloy during the directional pulling process of the pulling rod 20;

[0055] (4) First solidification stage: Start the pulling device 12 to pull the molten metal into the Ga-In-Sn liquid metal cooling medium 19 in the cooling tank 23 for directional solidification; the molten metal solidifies under the action of the first external magnetic field, and the magnetic field mainly acts on the solid-liquid interface of the material; the first external magnetic field can be a transverse steady magnetic field, a longitudinal steady magnetic field, a transverse traveling wave magnetic field, a longitudinal traveling wave magnetic field, or a composite magnetic field formed by any two of the four magnetic fields;

[0056] (5) Second solidification stage: when the material is immersed in the Ga-In-Sn liquid metal cooling medium at a distance of 19x1, the position of the magnetic field generator 5 is adjusted so that the material solidifies under the action of a second external magnetic field; the second external magnetic field has a different type, intensity or frequency from the first external magnetic field;

[0057] (6) The nth solidification stage: the material is immersed in the Ga-In-Sn liquid metal cooling medium x n-1 When the distance is n, the position of the magnetic field generator 5 is adjusted so that the material solidifies under the action of the nth external magnetic field;

[0058] (7) After the metal material is cooled to room temperature, it is taken out and the metal material has a solidified structure with multiple sections of different directional growth characteristics along the radial direction.

[0059] This embodiment also provides a device for preparing metal materials by multi-magnetic field assisted directional solidification, which is applied to the method for preparing metal materials by multi-magnetic field assisted directional solidification, such as Figure 2-Figure 8 As shown, it includes a melting device, a magnetic field generating device, a vacuum chamber 9, a cooling tank 23, a temperature measuring system, a pulling device 12, a vacuum system and an experimental atmosphere source 8;

[0060] The cooling tank 23 is arranged at the bottom of the vacuum cavity 9, the smelting device is arranged in the vacuum cavity 9, the magnetic field generating device is arranged in the cooling tank 23, the vacuum pumping system is connected to the inner cavity of the vacuum cavity 9, and is used to evacuate the vacuum cavity 9, and the experimental atmosphere source 8 is connected to the inner cavity of the vacuum cavity 9, and is used to fill the vacuum cavity 9 after evacuation with the experimental atmosphere; the temperature measuring system is used to monitor the upper surface temperature of the sample 24 in the vacuum cavity 9;

[0061] The smelting device includes an induction coil 1, a graphite sleeve 2 and a crucible 3; the graphite sleeve 2 is a cylindrical graphite, the induction coil 1 is a copper coil 15 with circulating cooling water flowing inside, the induction coil 1 is wound around the outside of the graphite sleeve 2, the crucible 3 is arranged in the graphite sleeve 2, the bottom of the crucible 3 is connected to the pulling device 12, and the crucible 3 is controlled by the pulling device 12 to move vertically in the graphite sleeve 2; an annular graphite pad is arranged at the bottom of the graphite sleeve 2, a ceramic pad is arranged at the bottom of the graphite pad to reduce the heat radiation received by the magnetic field generating device, and a graphite felt is arranged between the ceramic pad and the top plate of the cooling tank 23 at the bottom thereof, so as to reduce the temperature gradient inside the ceramic pad and prevent the ceramic pad from breaking;

[0062] The magnetic field generating device includes a magnetic field generator 5, a heat protection sleeve 25, a magnetic field control device and a power supply device; the magnetic field generator 5 includes a longitudinal steady magnetic field generator, a transverse steady magnetic field generator, a longitudinal traveling wave magnetic field generator and a transverse traveling wave magnetic field generator;

[0063] The longitudinal steady magnetic field generator is composed of an annular permanent magnet 13 and a heat protection sleeve 25 sleeved outside the annular permanent magnet 13, and can generate a steady magnetic field parallel to the directional solidification direction;

[0064] The transverse constant magnetic field generator includes two square permanent magnets 14 placed opposite to each other and a heat protection sleeve 25 sleeved outside the square permanent magnets 14. The N poles and S poles of the two square permanent magnets 14 are placed opposite to each other, and can provide a transverse constant magnetic field.

[0065] The longitudinal traveling wave magnetic field generator is composed of a longitudinally distributed copper coil 15 and a heat protection sleeve 25 sleeved outside the copper coil 15, and can generate a traveling wave magnetic field parallel to the directional solidification direction;

[0066] The transverse traveling wave magnetic field generator includes two rectangular coils 16 placed opposite to each other and a heat protection sleeve 25 sleeved outside the rectangular coils 16, which can generate a transverse traveling wave magnetic field;

[0067] Specifically, the annular permanent magnet 13 and the copper coil 15 are arranged on the top of the cooling tank 23, the two are arranged concentrically, and the annular permanent magnet 13 is located on the periphery of the copper coil 15; two square permanent magnets 14 and two rectangular coils 16 are respectively arranged on both sides of the top of the cooling tank 23, and the pull rod 20 passes through the center of the copper coil 15 and passes between the square permanent magnet 14 and the rectangular coil 16. The magnetic field generating device can provide 0-5T transverse steady magnetic field, 0-5T longitudinal steady magnetic field, 0-200mT longitudinal traveling wave magnetic field and 0-200mT transverse traveling wave magnetic field, and the traveling wave magnetic field frequency is 10-500Hz.

[0068] The magnetic field control device includes a magnetic field lifting component and a magnetic field translation component, wherein the magnetic field lifting component is composed of a lifting rod 22 and a servo motor 21, which is used to control the lifting and lowering of the annular permanent magnet 13 and the copper coil 15 in the cavity of the cooling tank 23; the bottom end of the lifting rod 22 is connected to the servo motor 21, and the top end is connected to the annular permanent magnet 13 and the copper coil 15 at the same time through a lifting platform.

[0069] The magnetic field translation assembly includes a translation support rod 18 and a servo motor 17, which are used to control the horizontal position of the square permanent magnet 14 and the rectangular coil 16; two servo motors 17 are provided, and the two servo motors 17 are respectively connected to a translation support rod 18, and the translation support rod 18 is connected to a push plate, and the two push plates are respectively installed on the two square permanent magnets 14 and the two rectangular coils 16. The two servo motors 17 can control the lateral position of the square permanent magnet 14 and the rectangular coil 16 respectively.

[0070] The power supply device is used to supply power to the internal coil of the magnetic field generating device; the power supply device includes an electrode flange and a power supply, the electrode flange is installed on the side wall of the vacuum chamber 9, and the electrode flange is connected to the external power supply and the internal longitudinal traveling wave magnetic field generator and transverse traveling wave magnetic field generator through a wire.

[0071] In this specific embodiment, the vacuum system includes a mechanical pump 6 and a molecular pump 7. The mechanical pump 6 is connected to the molecular pump 7. The molecular pump 7 is connected to the cavity of the vacuum cavity 9 by a pipeline. The vacuum system can evacuate the cavity to 1×10 -4 -1×10 -6 Pa; the experimental atmosphere source 8 is argon gas. After the vacuum system evacuates the cavity to a vacuum, the solenoid valve can be opened to backfill the vacuum cavity 9 with argon gas.

[0072] In this specific embodiment, the pulling device 12 includes a pulling motor and a pulling rod 20. The bottom of the pulling rod 20 is connected to the pulling motor. Driven by the pulling motor, the pulling rod 20 can achieve a pulling speed of 1-500 μm / s. The top of the pulling rod 20 is connected to the crucible 3 through a molybdenum alloy adapter. The crucible 3 is a cylindrical corundum crucible 3 with a flat bottom.

[0073] In this specific embodiment, the heat protection sleeve 25 is an alumina ceramic sleeve, which is used to prevent the internal magnetic field generator 5 from being damaged by high temperature.

[0074] In this specific embodiment, the cooling tank 23 includes a cylindrical demagnetized stainless steel tank body, a Ga-In-Sn liquid metal cooling medium 19 and a copper tube with circulating cooling water. The Ga-In-Sn liquid metal cooling medium 19 is installed in the tank body, and the copper tube is located in the Ga-In-Sn liquid metal cooling medium 19 in the tank body.

[0075] In this specific embodiment, the side walls of the vacuum cavity 9 and the cooling tank 23 are both double-layer water-cooled structures with water-cooled interlayers inside, and the water-cooled interlayers of the vacuum cavity 9 and the cooling tank 23 are connected to the water chiller 10 through pipelines.

[0076] In this specific embodiment, the temperature measuring device is an infrared thermometer 11, which is installed on the top of the vacuum chamber 9. The infrared thermometer 11 has a temperature measuring range of 500-2500°C and can monitor the upper surface temperature of the sample 24 in real time.

[0077] Embodiment 1:

[0078] This embodiment provides an experimental scheme for directional solidification of metal materials under the action of a multi-level magnetic field.

[0079] (1) High-purity Ni and high-purity Cu with a purity of 99.995% are selected to prepare a Ni-30Cu (wt.%) alloy, which is smelted in a high vacuum suction casting furnace. After the raw materials are fully and evenly melted, they are suction cast to obtain a Ni-Cu alloy rod.

[0080] (2) The annular permanent magnet 13 with an outer diameter of 60 mm, an inner diameter of 36 mm, and a thickness of 60 mm provides the first magnetic field, the 200-turn copper coil 15 with an inner diameter of 14 mm provides the second magnetic field, the 50×50×50 mm square permanent magnet 14 provides the third magnetic field, and the 50×50 mm 200-turn rectangular coil 16 provides the fourth magnetic field. The magnetic field generator 5 is installed in the thermal protection sleeve 25. The annular permanent magnet 13 and the longitudinally distributed copper coil 15 are coaxially placed with the sample 24; the square permanent magnet 14 and the rectangular coil 16 are arranged with the N pole and the S pole facing each other. The servo motor is started to make the first magnetic field act on the solid-liquid interface of the metal melt.

[0081] The alloy rod is placed in a crucible 3 with an inner diameter of 10 mm and an outer diameter of 12 mm. The crucible 3 is bonded to the upper end of the pulling rod 20 using an adhesive prepared from alumina powder and silica sol. A graphite sleeve 2 with an outer diameter of 40 mm, an inner diameter of 20 mm and a height of 200 mm is placed.

[0082] (4) Use the vacuum system to evacuate to 5×10 -6 Pa, and then recoil high-purity argon gas into the chamber to 0.5×10 5 Pa.

[0083] (5) Turn on the high-frequency power supply for heating and the infrared thermometer 11. When the infrared thermometer 11 shows that the alloy temperature rises to an overheated temperature of 200 K, the experiment begins.

[0084] (6) First solidification stage: start the power supply of the pulling device 12, and immerse the sample 24 into the liquid metal at a rate of 5 μm / s; second solidification stage: after the sample 24 is immersed in the liquid metal for 5 mm, adjust the second level magnetic field to act on the solid-liquid interface of the material; third solidification stage: after the sample 24 is immersed in the liquid metal for 10 mm, adjust the third level magnetic field to act on the solid-liquid interface of the material; fourth solidification stage: after the sample 24 is immersed in the liquid metal for 15 mm, adjust the fourth level magnetic field to act on the solid-liquid interface of the material.

[0085] (7) After the sample 24 is immersed in the liquid metal for 20 mm, the power supply of the pulling device 12, the coil power supply and the high-frequency heating power supply are turned off. After the sample 24 is cooled to room temperature, the cavity is opened, and the sample 24 and the crucible 3 are taken out together. After demolding, the metal material prepared under the condition of the fourth-level magnetic field is obtained.

[0086] Embodiment 2:

[0087] This embodiment provides an experimental scheme for directional solidification of metal materials by applying a multi-level composite magnetic field.

[0088] (1) A Ni-25Al (wt.%) alloy is prepared by selecting high-purity Ni with a purity of 99.995% and high-purity Al with a purity of 99.95%, and smelting is performed in a high vacuum suction casting furnace. After the raw materials are fully and evenly melted, suction casting is performed to obtain a Ni-Al alloy rod.

[0089] (2) The annular permanent magnet 13 with an outer diameter of 60 mm, an inner diameter of 36 mm, and a thickness of 60 mm and a 200-turn copper coil 15 with an outer diameter of 34 mm and an inner diameter of 14 mm provide the first-level magnetic field simultaneously, and the 50×50×50 mm square permanent magnet 14 and the 50×20 mm 200-turn rectangular coil 16 provide the second-level magnetic field simultaneously. The annular permanent magnet 13 and the longitudinally distributed copper coil 15 are placed coaxially with the sample 24; the N pole and the S pole of the rectangular coil 16 are placed opposite to each other with a distance of 16 mm, and the N pole and the S pole of the square permanent magnet 14 are arranged opposite to each other with a distance of 58 mm. The first-level magnetic field is adjusted to the solid-liquid interface of the metal material.

[0090] (3) The alloy rod is placed in a crucible 3 with an inner diameter of 10 mm and an outer diameter of 12 mm. The crucible 3 is bonded to the upper end of the pulling rod 20 using an adhesive prepared from alumina powder and silica sol. A graphite sleeve 2 with an outer diameter of 40 mm, an inner diameter of 20 mm, and a height of 200 mm is placed.

[0091] (4) Use a vacuum pump to evacuate to 1×10 -5 Pa, and then recoil high-purity argon gas into the chamber to 0.5×10 5 Pa.

[0092] (5) Turn on the high-frequency power supply heating and the infrared thermometer 11. The infrared data shows that the experiment starts when the alloy temperature rises to overheating 300K.

[0093] (6) First solidification stage: start the power supply of the pulling device 12 and the coil power supply, and immerse the sample 24 in the liquid metal at a rate of 50 μm / s; second solidification stage: after the sample 24 is immersed in the liquid metal for 15 mm, adjust the first-level magnetic field to a position away from the sample 24; start the servo motor 17 so that the second-level magnetic field acts on the solid-liquid interface of the sample 24.

[0094] (7) After the sample 24 is immersed in the liquid metal for 20 mm, the power supply of the pulling device 12, the coil power supply and the high-frequency heating power supply are turned off. After the sample 24 is cooled to room temperature, the cavity is opened and the sample 24 and the crucible 3 are taken out together. After demolding, the metal material prepared under the two magnetic field coupling conditions is obtained.

[0095] Example 3

[0096] This embodiment provides a method for directional solidification of a metal material under a single magnetic field.

[0097] (1) A Ti-6Al-4V (wt.%) alloy is prepared by selecting high-purity Ti, high-purity Al and high-purity V alloys with a purity of 99.95%, and smelting is performed in a high vacuum suction casting furnace. After the raw materials are fully and evenly melted, suction casting is performed to obtain a Ti-6Al-4V alloy rod.

[0098] (2) A ring-shaped permanent magnet 13 with an outer diameter of 80 mm, an inner diameter of 15 mm and a thickness of 60 mm is selected to provide a longitudinal steady magnetic field.

[0099] (3) The alloy rod is placed in a crucible 3 with an inner diameter of 10 mm and an outer diameter of 12 mm. The crucible 3 is bonded to the upper end of the pulling rod 20 using an adhesive prepared from alumina powder and silica sol. A graphite sleeve 2 with an outer diameter of 40 mm, an inner diameter of 20 mm, and a height of 200 mm is placed.

[0100] (4) Use a vacuum pump to evacuate to 1×10 -5 Pa, and then recoil high-purity argon gas into the chamber to 0.5×10 5 Pa.

[0101] (5) Turn on the high-frequency power supply heating and the infrared detection probe. When the infrared data shows that the alloy temperature rises to an overheated 100K, start the power supply of the pulling device 12, and the sample 24 is immersed in the liquid metal at a rate of 200 μm / s.

[0102] (6) After the sample 24 is immersed in the liquid metal for 50 mm, the pulling power supply and the high-frequency heating power supply are turned off. After the sample 24 is cooled to room temperature, the cavity is opened, and the sample 24 and the crucible 3 are taken out together. After demolding, the directionally solidified metal material is obtained by applying a longitudinal constant magnetic field.

[0103] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A device for preparing metal materials by multi-magnetic field assisted directional solidification, characterized in that: It includes a melting device, a magnetic field generating device, a vacuum chamber, a cooling tank, a temperature measuring system, a pulling device, a vacuum pumping system and an experimental atmosphere source; The cooling tank is arranged at the bottom of the vacuum cavity, the smelting device is arranged in the vacuum cavity, the magnetic field generating device is arranged in the cooling tank, the vacuum pumping system is connected to the inner cavity of the vacuum cavity, and is used to evacuate the vacuum cavity, and the experimental atmosphere source is connected to the inner cavity of the vacuum cavity, and is used to fill the vacuum cavity after evacuation with the experimental atmosphere; the temperature measuring system is used to monitor the upper surface temperature of the sample in the vacuum cavity; The smelting device comprises an induction coil, a graphite sleeve and a crucible; the graphite sleeve is cylindrical graphite, the induction coil is wound around the outside of the graphite sleeve, the crucible is arranged in the graphite sleeve, the bottom of the crucible is connected to the pulling device, and the pulling device controls the crucible to move vertically in the graphite sleeve; an annular graphite pad is arranged at the bottom of the graphite sleeve, a ceramic pad is arranged at the bottom of the graphite pad, and a graphite felt is arranged between the ceramic pad and the top plate of the cooling tank at the bottom thereof; The pulling device comprises a pulling motor and a pulling rod, the bottom of the pulling rod is connected to the pulling motor, and the top of the pulling rod is connected to the crucible through a molybdenum alloy adapter, and the crucible is a cylindrical corundum crucible with a flat bottom; The magnetic field generating device comprises a magnetic field generator, a heat protection sleeve, a magnetic field control device and a power supply device; the magnetic field generator comprises a longitudinal steady magnetic field generator, a transverse steady magnetic field generator, a longitudinal traveling wave magnetic field generator and a transverse traveling wave magnetic field generator; The longitudinal steady magnetic field generator is composed of an annular permanent magnet and a heat protection sleeve sleeved outside the annular permanent magnet, and can generate a steady magnetic field parallel to the directional solidification direction; The transverse constant magnetic field generator comprises two square permanent magnets placed opposite to each other and a heat protection sleeve sleeved outside the square permanent magnets, wherein the N poles and S poles of the two square permanent magnets are placed opposite to each other, and can provide a transverse constant magnetic field; The longitudinal traveling wave magnetic field generator is composed of a longitudinally distributed copper coil and a heat protection sleeve sleeved outside the copper coil, and can generate a traveling wave magnetic field parallel to the directional solidification direction; The transverse traveling wave magnetic field generator comprises two rectangular coils placed opposite to each other and a heat protection sleeve sleeved outside the rectangular coils, and is capable of generating a transverse traveling wave magnetic field; The annular permanent magnet and the copper coil are arranged on the top of the cooling tank, the two are arranged concentrically, and the annular permanent magnet is located on the periphery of the copper coil; the two square permanent magnets and the two rectangular coils are respectively arranged on both sides of the top of the cooling tank, and the pull rod passes through the center of the copper coil and passes between the square permanent magnet and the rectangular coil; The magnetic field control device includes a magnetic field lifting component and a magnetic field translation component, wherein the magnetic field lifting component is composed of a lifting rod and a servo motor 1, which is used to control the lifting and lowering of the annular permanent magnet and the copper coil in the cooling tank cavity; the magnetic field translation component includes a translation support rod and a servo motor 2, which is used to control the horizontal position of the square permanent magnet and the rectangular coil; The power supply device is used to supply power to the internal coil of the magnetic field generating device.

2. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The vacuum pumping system comprises a mechanical pump and a molecular pump, the mechanical pump is connected to the molecular pump, and the molecular pump pipeline is connected to the vacuum chamber.

3. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The induction coil is a copper coil with circulating cooling water flowing inside.

4. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The heat protection sleeve is an alumina ceramic sleeve.

5. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The cooling tank comprises a cylindrical demagnetized stainless steel tank body, a Ga-In-Sn liquid metal cooling medium and a copper tube with circulating cooling water. The Ga-In-Sn liquid metal cooling medium is installed in the tank body, and the copper tube is located in the Ga-In-Sn liquid metal cooling medium in the tank body.

6. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The power supply device includes an electrode flange and a power supply; the electrode flange is installed on the side wall of the vacuum chamber, and the electrode flange connects the external power supply with the internal longitudinal traveling wave magnetic field generator and transverse traveling wave magnetic field generator through a wire.

7. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The side walls of the vacuum cavity and the cooling tank are both double-layer water-cooled structures with water-cooled interlayers inside, and the water-cooled interlayers of the vacuum cavity and the cooling tank are connected to a water cooler through pipelines.

8. The device for preparing metal materials by multi-magnetic field assisted directional solidification according to claim 1, characterized in that: The temperature measurement system is an infrared thermometer; the infrared thermometer is installed on the top of the vacuum chamber.

9. A method for preparing metal materials by multi-magnetic field assisted directional solidification, using the device for preparing metal materials by multi-magnetic field assisted directional solidification according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Select high-purity bulk metal raw materials and configure the required metal materials in proportion; process the materials into suitable sizes, load them into a ceramic crucible, and connect the crucible to a pull rod; (2) Four magnetic field generators are installed in the cooling tank corresponding to the moving device; the working position of the magnetic field generator can be adjusted by the magnetic field lifting assembly and the magnetic field translation assembly; (3) evacuating the vacuum chamber; melting the alloy material into a metal melt to achieve directional growth of the alloy during the directional pulling process of the pulling rod; (4) First solidification stage: starting the pulling device to pull the molten metal into the Ga-In-Sn liquid metal cooling medium in the cooling tank for directional solidification; the molten metal solidifies under the action of a first external magnetic field, and the magnetic field mainly acts on the solid-liquid interface of the material; the first external magnetic field can be a transverse steady magnetic field, a longitudinal steady magnetic field, a transverse traveling wave magnetic field, a longitudinal traveling wave magnetic field, or a composite magnetic field formed by any two of the four magnetic fields; (5) Second solidification stage: when the material is immersed in the Ga-In-Sn liquid metal cooling medium at a set distance, the position of the magnetic field generator is adjusted so that the material solidifies under the action of a second external magnetic field; the second external magnetic field has a different type, intensity or frequency from the first external magnetic field; (6) nth solidification stage: when the material is immersed in the Ga-In-Sn liquid metal cooling medium at a set distance, the position of the magnetic field generator is adjusted so that the material solidifies under the action of the nth external magnetic field; (7) After the metal material is cooled to room temperature, it is taken out and the metal material has a solidified structure with multiple sections of different directional growth characteristics along the radial direction.

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