Zone-melting directional solidification device and preparation method of high-orientation metal

Abstract

The invention provides a zone-melting directional solidification device and a preparation method of high-orientation metal, the zone-melting directional solidification device comprises a raw material rod protection pipe, a raw material rod fixing mechanism and a raw material rod displacement mechanism are arranged at one end of the raw material rod protection pipe, and an induction heating assembly is arranged on the outer side of the raw material rod protection pipe; the other end, away from the raw material rod fixing mechanism, of the raw material rod protection pipe is provided with a heat insulation piece, and a heat insulation layer is arranged in the pipe wall of the raw material rod protection pipe. A heat conduction base is arranged on the raw material rod fixing mechanism, located in the raw material rod protection pipe and is a cylinder or a circular truncated cone with a hollow cavity. According to the directional solidification device and the preparation method, the high-orientation-degree material is prepared through the structural design of the device and the regulation and control of the temperature gradient direction and the smelting and heating uniformity of the raw materials, the crystal growth direction is close to the axial direction of a raw material rod, the internal texture and orientation of the material are uniform and obvious, and the orientation degree is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation, and relates to a metal preparation method based on directional solidification, and in particular to a zone melting directional solidification device and a preparation method for highly oriented metal. Background Art

[0002] When the grains inside a material have a crystallographically preferred orientation, a so-called texture is formed, which makes the material have obvious anisotropy, that is, the physical and mechanical properties of the material in different directions will vary greatly. For example, in the semiconductor industry, the orientation of silicon wafers <100> Orientation usually has higher electrical conductivity and carrier mobility, so it is often used to manufacture high-speed and high-efficiency electronic devices; in aircraft engines, key components such as turbine blades often use directional solidification technology to obtain ideal crystal orientation, thereby improving high-temperature strength and fatigue resistance. In addition, when manufacturing high-performance alloys and functional materials, by controlling crystal orientation, the thermal conductivity, electrical conductivity, magnetic and mechanical properties of the material can be significantly improved. Therefore, controlling and optimizing crystal orientation is an important way to improve material performance and develop new materials.

[0003] In order to prepare metal materials with specific orientation, directional solidification technology is currently widely used. The solidification process is controlled by adjusting the movement direction of the solid-liquid interface and the solidification rate, thereby achieving precise control of the crystal orientation.

[0004] Zone melting and solidification technology is a typical directional solidification process method. This method uses an induction coil to locally heat the cast master alloy raw material rod to melt it, and cools one end of the raw material rod at the same time, so as to form an axial temperature gradient between the heating part and the cooling end of the raw material rod. The relative position of the raw material rod and the induction heating coil is changed by an automatic displacement device to achieve remelting and sequential solidification of the master alloy to form a texture structure with a specific orientation. This process technology is generally used for material impurity removal and purification, and can also be used for oriented crystal material growth. CN114318497A discloses a zone melting furnace for preparing alloy crystal rods. By arranging a top fixing sleeve at the upper end of the melting cavity in the zone melting furnace, and arranging a melting cavity adjustment rod and a bottom support rod at the lower end, the melting cavity is coaxial with the hole on the heater, so that the bismuth telluride-based alloy crystal rod is heated to the same degree, the problem of uneven heating during the zone melting process is improved, the zone melting efficiency is improved, and the bismuth telluride-based oriented crystal rod is prepared. CN117385447A discloses a suspension zone melting directional solidification device and method thereof, which realizes multiple zone melting of polycrystalline rods by arranging a number of high-frequency coils in the furnace body at intervals in the vertical direction, so that the single crystal rod finally taken out of the furnace body has a lower internal impurity content and a more uniform structure, which is convenient for producing long-length single crystal rods and improving production efficiency. The above device and method realize uniform induction heating and control the direction of grain growth by adding a positioning device or magnetic field regulation.

[0005] There are still two problems with the existing regional melting and solidification equipment: on the one hand, the local heating of the raw material rod is often uneven, which is related to the difficulty of coaxiality between the master alloy raw material rod and the induction heating coil, which will lead to incomplete melting and may cause sudden collapse of the molten zone. The surface of the prepared material is bumpy and the orientation degree is extremely poor; on the other hand, the temperature gradient of the solidification process is mainly in the same direction as the axis of the raw material rod. This temperature gradient direction will cause the internal grain orientation direction of some materials to form a certain angle with the axis when they grow, and the preferred growth direction actually required is not necessarily growth along the ideal crystallographic close-packed plane.

[0006] Therefore, based on the above two problems, the present invention provides a zone melting directional solidification device and a method for preparing highly oriented metal. Summary of the invention

[0007] The object of the present invention is to provide a zone melting directional solidification device and a method for preparing a highly oriented metal, so as to adjust the temperature gradient direction of a raw material rod, improve the uniformity of smelting and heating, and prepare a metal material with a high degree of orientation.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a zone melting directional solidification device, the zone melting directional solidification device comprising:

[0010] A raw material rod protection tube, one end of which is provided with a raw material rod fixing mechanism and a raw material rod displacement mechanism, and an induction heating component is provided on the outer side of the raw material rod protection tube;

[0011] A heat insulation member is provided at the other end of the raw material rod protection tube away from the raw material rod fixing mechanism, and a heat insulation layer is provided in the tube wall of the raw material rod protection tube;

[0012] The raw material rod fixing mechanism is provided with a heat-conducting base, the heat-conducting base is located in the raw material rod protection tube, and the heat-conducting base is a cylinder or a frustum with a hollow cavity.

[0013] The directional solidification device provided by the present invention is based on the regional smelting technology. During the smelting process, the raw material rod protection tube plays a role in shaping and fixing. A heat insulation layer is arranged on the inner wall of the raw material rod protection tube. The heat insulation layer forms a hollow tubular structure similar to the raw material rod protection tube. The heat insulation layer adopts a conductive heat insulation material. When in use, it is coaxial with the raw material rod to realize secondary induction heating and improve the uniformity of local heating of the raw material rod. A heat insulation piece is arranged at the open end of the raw material rod protection tube. When the device is in use, after the raw material rod is placed in the raw material rod protection tube, The thermal insulation parts at the top of the raw material rod cooperate with the thermal insulation layer in the wall of the raw material rod protection tube to change the temperature gradient in the vertical direction of the raw material rod during regional melting, so that the heat flow diffuses downward along the axial direction of the raw material rod, and the growth orientation of the material is regulated; at the same time, the heat conductive base is structurally designed, and the heat conductive base is a frustum with a certain taper, so that the heat flow diffuses along the direction of the heat conductive base, thereby changing the heat transfer direction, forming a temperature gradient with a certain inclination angle, and "straightening" the crystal growth direction along the axis of the raw material rod, thereby improving the axial orientation of the material.

[0014] In the present invention, the raw material rod displacement mechanism is a conventional moving device in the art, which can realize the movement of the smelting cavity and the raw material rod for regional induction heating, and the present invention does not specifically limit its structure.

[0015] Preferably, the material of the thermal insulation component includes boron nitride.

[0016] Preferably, the diameter of the thermal insulation component is 1.0-1.2 times the diameter of the raw material rod, for example, it can be 1.0 times, 1.05 times, 1.1 times, 1.15 times or 1.2 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the height of the thermal insulation component is 1 / 4 to 1 / 2 of the length of the raw material rod, for example, it can be 1 / 4, 1 / 3 or 1 / 2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the thermal insulation layer is made of graphite paper.

[0019] Preferably, the thickness of the thermal insulation layer is 0.1-5 mm, for example, it can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the height of the thermal insulation layer is 1.0-1.2 times the length of the raw material rod, for example, it can be 1.0 times, 1.05 times, 1.1 times, 1.15 times or 1.2 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, when the thermally conductive base is a truncated cone, the angle between the hypotenuse of the truncated cone and the axial direction of the thermally conductive base is 0-30°, excluding 0, for example, it can be 0.1°, 1°, 5°, 10°, 15°, 20°, 25° or 30°, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the cross-section of the hollow cavity of the heat-conducting base is square or trapezoidal.

[0023] Preferably, when the cross-section of the hollow cavity of the thermally conductive base is a trapezoid, the angle between the hypotenuse of the trapezoid and the axial direction of the thermally conductive base is 0-30°, excluding 0, for example, it can be 0.1°, 1°, 5°, 10°, 15°, 20°, 25° or 30°, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the ratio of the thickness of the top surface of the thermally conductive base to the height of the thermally conductive base is 0-0.5, excluding 0, for example, it can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In the present invention, the top surface of the heat-conducting base is the surface in contact with the raw material rod.

[0026] Preferably, the melting point of the material of the heat-conducting base is higher than the sum of the melting point and the superheat of the raw material rod.

[0027] Preferably, the material of the heat-conducting base includes heat-resistant steel and / or tungsten alloy.

[0028] Preferably, the hollow cavity of the heat-conducting base is filled with heat-insulating material.

[0029] In the present invention, a heat insulating material is filled in the hollow cavity of the heat conductive base to reduce the thermal conductivity therein, thereby promoting the heat flow to diffuse along the bottom direction of the heat conductive base, and further regulating the heat transfer direction.

[0030] Exemplarily, the thermal insulation material includes any one of glass fiber, asbestos, rock wool, perlite or silicate, or a combination of at least two thereof.

[0031] Preferably, the raw material rod protection tube is a double-layer quartz tube.

[0032] In a second aspect, the present invention provides a method for preparing a highly oriented metal, the method using the zone melting directional solidification device described in the first aspect, the method comprising the following steps:

[0033] Place the metal raw material rod axially into the raw material rod protection tube of the zone melting directional solidification device, place it on a heat-conducting base, place heat-insulating parts, seal the zone melting directional solidification device, and then turn on the induction heating component to a predetermined temperature, control the raw material rod displacement mechanism to move the metal raw material rod, so that the induction heating component moves axially relative to the metal raw material rod for zone melting, and the induction heating component moves from one end of the metal raw material rod to the other end to end the melting.

[0034] In the present invention, a zone melting solidification furnace cavity is provided outside the zone melting directional solidification device, and the method for sealing the zone melting directional solidification device comprises closing the cavity cover of the zone melting solidification furnace cavity, and filling it with argon gas after vacuuming.

[0035] In the present invention, the “high orientation” refers to that the angle between the crystal orientation growth direction in the material and the axial direction of the material is ≤20°.

[0036] Preferably, during the relative movement of the induction heating component, the temperature variation range is 0-50°C, for example, it can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the relative movement speed of the induction heating component is 0.05-15 mm / min, for example, it can be 0.05 mm / min, 0.1 mm / min, 0.5 mm / min, 1 mm / min, 2 mm / min, 4 mm / min, 5 mm / min, 6 mm / min, 8 mm / min, 10 mm / min, 12 mm / min, 14 mm / min or 15 mm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the metal raw material rod is prepared by vacuum induction heating melting and casting.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The zone melting directional solidification device provided by the present invention regulates the temperature gradient direction and melting heating uniformity of the raw materials through the device structure design, and prepares high-orientation materials. The crystal growth direction is close to the axial direction of the raw material rod, the internal texture organization and orientation of the material are uniform and obvious, and the orientation degree is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic structural diagram of a zone melting directional solidification device provided in Example 1;

[0042] Among them: 1-quartz tube; 11-inner quartz protection tube; 12-outer quartz protection tube; 2-raw material rod fixing device; 3-raw material rod displacement mechanism; 4-induction heating coil; 5-thermal insulation layer; 6-thermal conductive base; 7-thermal insulation component; 8-master alloy raw material rod; 81-local melting area;

[0043] Figure 2 is a schematic cross-sectional structure diagram of a heat-conducting base of a zone melting directional solidification device provided in Example 1;

[0044] Figure 3 is a metallographic image of a highly oriented metal material prepared in Application Example 1;

[0045] Figure 4 is a metallographic diagram of the metal material prepared in comparative application example 1;

[0046] Figure 5 This is a metallographic diagram of the metal material prepared in comparative application example 2. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0048] Example 1

[0049] This embodiment provides a Figure 1 The zone melting directional solidification device shown comprises:

[0050] Quartz tube 1;

[0051] The lower end of the quartz tube 1 is provided with a raw material rod fixing device 2 and a raw material rod displacement mechanism 3;

[0052] An induction heating coil 4 is arranged outside the quartz tube 1;

[0053] The top of the quartz tube 1 is provided with a heat-insulating component 7 made of boron nitride, and the heat-insulating component 7 has a diameter of 12 mm and a height of 45 mm;

[0054] A heat-insulating layer 5 made of graphite paper is provided in the tube wall of the quartz tube 1, and the quartz tube 1 is divided into an inner quartz protection tube 11 and an outer quartz protection tube 12, and the thickness of the heat-insulating layer 5 is 0.25 mm;

[0055] The raw material rod fixing device 2 is provided with a heat-conducting base 6, and the heat-conducting base 6 is located in the quartz tube 1. The heat-conducting base 6 is a truncated cone with a hollow cavity. The cross-sectional schematic diagram of the heat-conducting base 6 is as shown in FIG. Figure 2 As shown;

[0056] The included angle α between the hypotenuse of the heat-conducting base 6 and the axial direction of the heat-conducting base is 30°;

[0057] The cross section of the hollow cavity of the heat-conducting base 6 is a trapezoid, and the angle β between the hypotenuse of the trapezoid and the axial direction of the heat-conducting base is 30°;

[0058] The thickness h of the top surface of the heat-conducting base 6 is 22.5 cm, the height H of the heat-conducting base 6 is 45 cm, and the ratio of the top thickness to the height h / H is 0.5;

[0059] The material of the heat-conducting base 6 is heat-resistant steel.

[0060] Comparative Example 1

[0061] This comparative example provides a zone melting directional solidification device. Compared with Example 1, no heat insulation layer is arranged inside the quartz tube of the directional solidification device, and the heat conductive base is a cylinder without a hollow cavity, that is, a solid cylinder. The diameter of the cylinder is the same as the top surface diameter of the cone in Example 1, and the rest is the same as Example 1.

[0062] Comparative Example 2

[0063] This comparative example provides a zone melting directional solidification device. Compared with Example 1, the heat-conducting base is a cylinder without a hollow cavity, that is, a solid cylinder. The diameter of the cylinder is the same as the top surface diameter of the cone in Example 1, and the rest is the same as Example 1.

[0064] Application Example 1

[0065] This application example provides a method for preparing a highly oriented metal material, using the zone melting directional solidification device provided in Example 1, and the preparation method comprises the following steps:

[0066] (1) Press Tb 0.3 Dy 0.7 Fe 2 Alloy Proportion Weigh the metal raw materials;

[0067] (2) melting the raw materials by vacuum induction heating in an argon atmosphere, casting the alloy round rods through a mold, polishing to remove the surface oxide scale and impurities of the alloy round rods, and then washing the surface dust particles with alcohol to obtain the master alloy raw rods;

[0068] (3) placing the master alloy raw material rod axially onto a fixed heat-conducting base in a zone melting directional solidification device, and placing a boron nitride heat-insulating component on the top of the master alloy raw material rod;

[0069] (4) After closing the chamber cover of the zone melting solidification furnace, the vacuum degree in the chamber is drawn to 2×10 -3 Pa, argon was introduced as a protective gas, and then the vacuum was evacuated to 2×10 -3 Pa, and finally introduce argon to -0.05MPa, turn on the induction melting power supply, slowly adjust the power output, and after the temperature rises to the preset temperature of 1050℃, move the alloy rod by manipulating the alloy rod displacement device. During the movement of the alloy rod, slowly adjust the power supply to control the temperature change amplitude to be less than 50℃. When the moving distance of the induction coil exceeds the length of the alloy rod, turn off the power supply, and after the alloy rod is completely cooled, fill the cavity with air to normal pressure, open the cavity cover and take out the alloy rod.

[0070] Comparative application example 1

[0071] This comparative application example provides a method for preparing a metal material. Compared with Application Example 1, the zone melting directional solidification device provided in Comparative Example 1 is used, and the rest is the same as Application Example 1.

[0072] Comparative Application Example 2

[0073] This comparative application example provides a method for preparing a metal material. Compared with Application Example 1, the zone melting directional solidification device provided in Comparative Example 2 is used, and the rest is the same as Application Example 1.

[0074] The metallographic photograph of the alloy rod prepared in Application Example 1 is as follows: Figure 3 As shown in FIG. 1 , it can be seen that the deviation angle between the growth direction of the strip texture in the sample and the axial direction of the alloy rod is small, only about 10°, and has a significantly higher orientation degree; the metallographic photograph of the alloy rod prepared in Example 1 is shown in FIG. Figure 4 As shown in FIG. 1 , it can be seen that without setting a heat insulation layer and using a solid heat conductive base, due to uneven heating, the zone melting sample is severely overburned, with many dense holes and no obvious orientation; the metallographic photograph of the alloy rod prepared in Example 2 is shown in FIG. Figure 5 As shown, it can be seen that the thermal conductive base adopts a solid cylinder without a hollow cavity. The zone melting sample shows an obvious strip texture organization with a relatively uniform orientation. However, compared with Application Example 1, the deviation angle between its growth direction and the axial direction of the alloy rod is still relatively large, about 23°.

[0075] In summary, the zone melting directional solidification device and the method for preparing highly oriented metals provided by the present invention provide a graphite paper thermal insulation layer in the device structure design, and design the heat conductive base as a hollow structure, so as to effectively regulate the crystal orientation growth method, the crystal growth direction is close to the axial direction of the raw material rod, and the material orientation degree is high.

[0076] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A zone melting directional solidification device, characterized in that: The zone melting directional solidification device comprises: A raw material rod protection tube, one end of which is provided with a raw material rod fixing mechanism and a raw material rod displacement mechanism, and an induction heating component is provided on the outer side of the raw material rod protection tube; A heat insulation member is provided at the other end of the raw material rod protection tube away from the raw material rod fixing mechanism, and a heat insulation layer is provided in the tube wall of the raw material rod protection tube; The raw material rod fixing mechanism is provided with a heat-conducting base, the heat-conducting base is located in the raw material rod protection tube, and the heat-conducting base is a cylinder or a frustum with a hollow cavity.

2. The melt-zone directional solidification device according to claim 1, characterized in that: The material of the thermal insulation component includes boron nitride; Preferably, the diameter of the heat-insulating member is 1.0-1.2 times the diameter of the raw material rod; Preferably, the height of the thermal insulation component is 1 / 4 to 1 / 2 of the length of the raw material rod.

3. The zone melting directional solidification device according to claim 1 or 2, characterized in that: The material of the heat insulation layer includes graphite paper; Preferably, the thickness of the thermal insulation layer is 0.1-5 mm; Preferably, the height of the thermal insulation layer is 1.0-1.2 times the length of the raw material rod.

4. The melt-zone directional solidification device according to any one of claims 1 to 3, characterized in that: When the heat-conducting base is a truncated cone, the angle between the hypotenuse of the truncated cone and the axial direction of the heat-conducting base is 0-30°, excluding 0; Preferably, the cross-section of the hollow cavity of the heat-conducting base is square or trapezoidal; Preferably, when the cross-section of the hollow cavity of the heat-conducting base is a trapezoid, the angle between the hypotenuse of the trapezoid and the axial direction of the heat-conducting base is 0-30°, excluding 0.

5. The melt-zone directional solidification device according to any one of claims 1 to 4, characterized in that: The ratio of the thickness of the top surface of the thermally conductive base to the height of the thermally conductive base is 0-0.5, and does not include 0.

6. The melt-zone directional solidification device according to any one of claims 1 to 5, characterized in that: The melting point of the material of the heat-conducting base is higher than the sum of the melting point and the superheat of the raw material rod.

7. The melt-zone directional solidification device according to any one of claims 1 to 6, characterized in that: The hollow cavity of the heat-conducting base is filled with heat-insulating material.

8. The melt-zone directional solidification device according to any one of claims 1 to 7, characterized in that: The raw material rod protection tube is a double-layer quartz tube.

9. A method for preparing a highly oriented metal, characterized in that: The preparation method uses the zone melting directional solidification device according to any one of claims 1 to 8, and the preparation method comprises the following steps: Place the metal raw material rod axially into the raw material rod protection tube of the zone melting directional solidification device, place it on a heat-conducting base, place heat-insulating parts, seal the zone melting directional solidification device, and then turn on the induction heating component to a predetermined temperature, control the raw material rod displacement mechanism to move the metal raw material rod, so that the induction heating component moves axially relative to the metal raw material rod for zone melting, and the induction heating component moves from one end of the metal raw material rod to the other end to end the melting.

10. The preparation method according to claim 9, characterized in that: During the relative movement of the induction heating assembly, the temperature changes by 0-50°C; Preferably, the relative movement speed of the induction heating component is 0.05-15 mm / min.

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