Preparation method and device of metal single crystal

Abstract

The invention relates to a preparation method and device of a metal single crystal in the technical field of metal material processing, and the preparation method comprises the following steps: heating to-be-prepared metal in a high-melting-point metal crucible to above a metal melting point in an electromagnetic induction heating mode to form a melt; metal single crystal seed crystals with the same components as the melt are fixed to the bottom of a seed crystal rod capable of moving up and down to make contact with the surface of the melt, and the top of the seed crystal rod is continuously cooled in a water cooling mode; in a temperature field capable of being accurately regulated and controlled, a seed crystal rod and a crucible are controlled to slowly and reversely rotate, the seed crystal rod is gradually pulled upwards, the temperature of the temperature field is adjusted, and directional growth of crystals is achieved through the links of seeding, necking down, shouldering, necking down, equal-diameter growth, ending and the like. After the directional growth of the crystal is completed, naturally cooling the crystal to room temperature, and taking out the metal single crystal; compared with the prior art, the device provided by the invention has the characteristics of wide application range, good control precision, high crystal quality and the like, and is suitable for popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material processing, and in particular relates to a method and device for preparing a metal single crystal, and belongs to the category of metal single crystal growth process technology. Background Art

[0002] Metal single crystals, with their exceptional anisotropic properties, play an indispensable role in numerous high-end fields, including aerospace, advanced electronics, and energy. In aerospace, for example, the unique properties of metal single crystals can significantly enhance the high-temperature and fatigue resistance of engine blades, thereby increasing engine efficiency and service life. In high-end electronics, their superior electrical properties can be used to manufacture high-performance chips, driving the miniaturization and efficiency of electronic devices. Therefore, the preparation technology of metal single crystals has long been a research hotspot in materials science.

[0003] Currently, traditional methods for producing metal single crystals primarily include zone melting, single crystal continuous casting, and Czochralski. The Czochralski method, with its advantages of high crystallization control precision and high crystal quality, has become a widely adopted metal single crystal production technology in industrial production. Existing Czochralski processes typically heat the metal melt using resistance heating or induction heating. However, in practical applications, these processes present a series of challenges that require urgent attention. First, unstable temperature field control easily leads to the formation of grain boundaries or polycrystalline structures during crystal growth, severely impacting crystal integrity and resulting in reduced final product performance. Second, chemical reactions between the crucible material and the metal can easily occur, reducing crystal purity and failing to meet the stringent purity requirements of high-end applications. Third, the lack of a precise thermal field gradient control system makes it difficult to precisely control the seed crystal undercooling. Both insufficient and excessive undercooling can lead to unstable growth interfaces, further compromising crystal growth quality. Fourth, insufficient control of crystal rotation and crucible rotation during crystal growth results in poor crystal orientation consistency and increased defects, significantly limiting the application and development of metal single crystal materials.

[0004] In summary, the many problems existing in the existing metal single crystal Czochralski process make it difficult for the prepared metal single crystal materials to meet the growing demand for high-end applications. Therefore, it is urgent to develop a metal single crystal preparation method and device with more uniform heating, more stable thermal field control, and higher crystal quality. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of unstable temperature field, poor crystal orientation control, and easy formation of polycrystalline structure in the existing Czochralski method for preparing metal single crystals, and to provide a method and device for preparing metal single crystals with high crystal quality and good control accuracy.

[0006] To achieve one of the above objects, the present invention is implemented according to the following technical solutions:

[0007] A method for preparing a metal single crystal, characterized by comprising the following steps:

[0008] S1, melt preparation: the metal to be prepared is placed in a high melting point metal crucible and heated by electromagnetic induction heating to above the melting point of the metal to form a melt;

[0009] S2, crystal growth preparation: A metal single crystal seed crystal with the same composition as the melt is fixed to the bottom of a seed crystal rod that can move up and down so as to contact the melt surface. The top of the seed crystal rod is continuously cooled by water cooling to form a stable thermal gradient to achieve crystal growth;

[0010] S3, crystal directional growth control: In a precisely controlled temperature field, the seed crystal rod and metal crucible are controlled to slowly rotate in opposite directions, gradually pulling the seed crystal rod upward and adjusting the temperature field to stabilize the growth interface. Through seeding, necking, shoulder release, shoulder reduction, equal diameter growth, and tailing, directional growth of the crystal is achieved.

[0011] In this step, the seed crystal rod and the metal crucible are controlled to rotate slowly in opposite directions to ensure the axial consistency of the crystal and avoid crystal structure defects.

[0012] S4, crystal extraction: After the directional growth of the crystal is completed, the pulling speed of the seed crystal rod is reduced to zero, and the heating power is gradually reduced to zero, the crystal is allowed to cool naturally to room temperature, and the metal single crystal is extracted.

[0013] Preferably, in step S1, the metal to be prepared is nickel metal, copper metal, iron metal, aluminum metal or titanium alloy metal with a purity of ≥99.99%.

[0014] Preferably, in step S2, the seed rod needs to be pretreated, and the pretreatment includes surface mechanical polishing and cleaning.

[0015] Preferably, in step S3, the pulling speed of pulling the seed rod upward is 0.01-20 mm / min.

[0016] Preferably, in step S3, the rotation speeds of the seed rod and the metal crucible are both 0.01-20 rpm.

[0017] To achieve the second objective, the present invention further provides a metal single crystal preparation device for implementing the above-mentioned metal single crystal preparation method, comprising a metal crucible, an electromagnetic induction coil disposed outside the metal crucible, an inner heat-insulating cylinder disposed outside the electromagnetic induction coil, an outer heat-insulating cylinder disposed outside the inner heat-insulating cylinder, a seed crystal rod that slides sequentially from top to bottom through the top of the outer heat-insulating cylinder and the top of the inner heat-insulating cylinder and extends into the metal crucible, and a drive rod that rotatably passes through the bottom of the outer heat-insulating cylinder and the bottom of the inner heat-insulating cylinder from bottom to top;

[0018] A water cooling jacket for cooling the seed crystal rod is provided at the middle position of the top of the outer heat-insulating cylinder, and a driving component 1 is provided at the top of the seed crystal rod to drive the seed crystal rod to move up and down and rotate;

[0019] The top end of the driving rod is provided with a crucible tray for supporting the metal crucible, and the bottom end of the driving rod is provided with a driving component 2, and the driving component 2 is provided below the bottom of the outer insulation cylinder;

[0020] The driving assembly 1 and the driving assembly 2 are respectively used to drive the seed crystal rod and the metal crucible to realize reverse rotation.

[0021] Preferably, the first drive assembly includes a portal bracket mounted on the top of the outer insulation cylinder, a telescopic rod mounted in the middle of the portal bracket's top, and a first servo motor mounted at the bottom of the telescopic rod. The output shaft of the first servo motor is in driving connection with the seed crystal rod. The telescopic rod controls the servo motor to raise and lower the seed crystal rod as needed, and the servo motor controls the seed crystal rod to rotate at a set speed.

[0022] Preferably, the telescopic rod is one of an electric telescopic rod, a pneumatic telescopic rod or a hydraulic telescopic rod, which can control the seed crystal rod to rise and fall as needed and control the pulling speed of the seed crystal rod.

[0023] Preferably, the second driving component includes a second servo motor, and the output shaft of the second servo motor is in transmission connection with the driving rod, so as to control the driving rod to rotate at a set speed.

[0024] Preferably, the bottom of the outer heat-insulating cylinder is provided with supporting legs.

[0025] The present invention also includes other steps, devices, or components that enable the normal use of the method and apparatus for preparing a metal single crystal, all of which are conventional techniques in the art. In addition, steps, devices, or components not specified in the present invention all employ conventional techniques in the art.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) Stable temperature field control: electromagnetic induction heating is used, with a stable heat source and uniform heating, effectively avoiding the impact of temperature fluctuations on crystal quality;

[0028] (2) Thermal gradient optimization: Use a water-cooling jacket to cool the seed crystal to form a stable growth interface and increase the probability of single crystal formation;

[0029] (3) Good structural purity: Use a metal crucible with a high melting point to reduce metal reactions and improve crystal purity;

[0030] (4) High crystal consistency: Through the coordinated control of the seed rod and crucible rotation, the crystal orientation consistency is improved and the grain boundary defects are reduced;

[0031] (5) Strong adaptability: This method is suitable for the single crystal growth of various metal materials and has a wide range of applications.

[0032] In summary, the present invention has the characteristics of wide application range, good control precision, high crystal quality, etc., and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a process flow chart of the present invention in Example 1 and Example 2.

[0034] Figure 2 Schematic diagram of the device structure of the present invention in Example 3. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are intended to explain the present invention but are not intended to limit the present invention.

[0036] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0037] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides a method for preparing a metallic nickel single crystal, comprising the following steps:

[0040] S1, melt preparation: nickel metal to be prepared with a purity of ≥99.99% is heated to 1600°C in a tungsten crucible with a high melting point by electromagnetic induction heating to completely melt the nickel metal to form a melt;

[0041] S2, crystal growth preparation: A nickel single crystal seed crystal with a crystal orientation of

[111] and a size of 50 mm × 6 mm × 6 mm is fixed on the bottom of a pre-treated seed crystal rod that can move up and down to contact the melt surface, and the top of the seed crystal rod is continuously cooled by water cooling to form a stable thermal gradient to achieve crystal growth; wherein, the pretreatment includes surface mechanical polishing and cleaning.

[0042] S3, Crystal Directional Growth Control: In a precisely controlled temperature field, the seed crystal rod and crucible are slowly rotated in opposite directions at 5 rpm. During the seeding phase, the seed crystal rod is gradually pulled upward at a pulling speed of 3 mm / min. After the seeding length reaches 100 mm, the pulling speed is increased to 5 mm / min to initiate necking. After the diameter is reduced to approximately 3 mm, the heating power is reduced by 0.5 kW and the seed crystal pulling speed is reduced to 3 mm / min to release the shoulder. When the diameter reaches 75 mm, the heating power is increased by 0.3 kW and the seed crystal pulling speed is increased to 5 mm / min to initiate shoulder reduction. After shoulder reduction, uniform diameter growth is initiated. The heating power is increased by 0.1 kW and the pulling speed is reduced to 1 mm / mm for every 10 mm of growth. Fine adjustments are made based on the diameter, with an increment of 1 ± 0.5 mm / min, to maintain a diameter of approximately 75 mm. After the growth length reaches 100 mm, the pulling speed is increased to 3 mm / min and the heating power is increased by 1 kW to complete the process, achieving crystal directivity.

[0043] In this step, the seed crystal rod and the metal crucible are controlled to rotate slowly in opposite directions to ensure the axial consistency of the crystal and avoid crystal structure defects.

[0044] S4, crystal extraction: After the directional growth of the crystal is completed, the pulling speed of the seed crystal rod is controlled to be reduced to zero, and the heating power is reduced to zero at a cooling rate of 5w / min. The crystal is allowed to cool naturally to room temperature, and finally a single crystal nickel with a diameter of 75mm, a length of 100mm and a growth direction of

[111] is extracted.

[0045] Testing has shown that the electrical conductivity of the prepared single crystal nickel is 23% IACS (International Annealed Copper Standard), the elongation at break is 25%, and the room temperature thermal conductivity is 92 W / (m·K).

[0046] Example 2

[0047] like Figure 1 As shown, this embodiment provides a method for preparing a metallic copper single crystal, comprising the following steps:

[0048] S1, melt preparation: copper metal to be prepared with a purity of ≥99.99% is heated to 1200°C in a molybdenum crucible with a high melting point by electromagnetic induction heating to completely melt the copper metal to form a melt;

[0049] S2, crystal growth preparation: A copper single crystal seed crystal with a crystal orientation of

[100] and a size of Φ10mm×100mm is fixed to the bottom of a pre-treated seed crystal rod that can move up and down to contact the melt surface, and the top of the seed crystal rod is continuously cooled by water cooling to form a stable thermal gradient to achieve crystal growth; wherein, the pretreatment includes surface mechanical polishing and cleaning.

[0050] S3, Crystal Directional Growth Control: Under a precisely controlled temperature field, the seed crystal rod rotates clockwise at 5 rpm and the molybdenum crucible rotates counterclockwise at 8 rpm to ensure axial alignment and avoid structural defects. During the seeding phase, the seed crystal rod is gradually pulled upward at a pulling rate of 4 mm / min. After the seeding length reaches 80 mm, the pulling rate is increased to 7 mm / min to begin necking. After the diameter is reduced to approximately 5 mm, the heating power is reduced by 0.8 kW and the seed crystal pulling speed is reduced to 3 mm / min to release the shoulder. When the diameter reaches 100 mm, the heating power is increased by 0.4 kW and the seed crystal pulling speed is increased to 4 mm / min to begin shouldering. After shouldering is completed, the pulling speed is fine-tuned to 2 ± 0.3 mm / min. Constant diameter growth is achieved at a heating rate of 0.5 kW per 50 mm of growth. After the growth length reaches 300 mm, the pulling speed is increased to 5 mm / min and the heating power is increased by 1.5 kW to complete the growth, achieving crystal directional growth.

[0051] S5, crystal extraction: After the directional growth of the crystal is completed, the pulling speed of the seed crystal rod is controlled to be reduced to zero, and the heating power is reduced to zero at a cooling rate of 15w / min. The crystal is allowed to cool naturally to room temperature, and finally a single crystal copper with a diameter of 100mm, a length of 300mm and a growth direction of

[100] is extracted.

[0052] The test results show that the electrical conductivity of the single crystal copper is 109% IACS (International Annealed Copper Standard), the elongation at break is 105%, and the room temperature thermal conductivity is 401 W / (m·K).

[0053] Example 3

[0054] like Figure 2 As shown, this embodiment provides a device for preparing a metallic nickel single crystal, comprising a tungsten crucible 1, an electromagnetic induction coil 2 disposed outside the tungsten crucible, an inner heat-insulating cylinder 3 disposed outside the electromagnetic induction coil, an outer heat-insulating cylinder 4 disposed outside the inner heat-insulating cylinder, a seed crystal rod 5 that slides sequentially from top to bottom through the top of the outer heat-insulating cylinder and the top of the inner heat-insulating cylinder and extends into the interior of the tungsten crucible, and a drive rod 6 that rotatably passes through the bottom of the outer heat-insulating cylinder and the bottom of the inner heat-insulating cylinder from bottom to top;

[0055] A water cooling jacket 7 for cooling the seed crystal rod is provided at the middle position of the top of the outer heat preservation cylinder, and a driving component 1 is provided at the top of the seed crystal rod to drive the seed crystal rod to move up and down and rotate;

[0056] The top end of the driving rod is provided with a crucible tray 8 for supporting the tungsten crucible, and the bottom end of the driving rod is provided with a driving component 2, which is arranged below the bottom of the outer insulation cylinder;

[0057] The driving rod and the seed rod rotate in opposite directions.

[0058] Specifically, the drive assembly 1 includes a portal bracket 9 mounted on the top of the outer insulation cylinder, a telescopic rod 10 located in the middle of the portal bracket's top, and a servo motor 11 located at the bottom of the telescopic rod. The output shaft of the servo motor 1 is in driving connection with the seed crystal rod. The telescopic rod controls the servo motor to raise and lower the seed crystal rod as needed, and the servo motor controls the seed crystal rod to rotate at a set speed.

[0059] Continuing with the above embodiment, the telescopic rod is an electric telescopic rod, which facilitates the control of the pulling speed of the seed rod. The second drive assembly includes a second servo motor 12, the output shaft of which is in transmission connection with the drive rod, for controlling the drive rod to rotate at a set speed.

[0060] In addition, support legs 13 are provided at the bottom of the outer heat-insulating cylinder to facilitate the installation and maintenance of the servo motor 2.

[0061] When in use, the nickel single crystal 14 is prepared and taken out according to the preparation method of the metal nickel single crystal in Example 1.

[0062] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

[0063] Example 4

[0064] The only difference between this embodiment and embodiment 3 is that this embodiment proposes a device for preparing a metallic copper single crystal, and replaces the tungsten crucible with a molybdenum crucible. When used, the copper single crystal is prepared and taken out according to the method for preparing the metallic copper single crystal in embodiment 2.

[0065] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a metal single crystal, characterized in that: The following steps are involved: S1, melt preparation: the metal to be prepared is placed in a high melting point metal crucible and heated by electromagnetic induction heating to above the melting point of the metal to form a melt; S2, crystal growth preparation: A metal single crystal seed crystal with the same composition as the melt is fixed to the bottom of a seed crystal rod that can move up and down so as to contact the melt surface. The top of the seed crystal rod is continuously cooled by water cooling to form a stable thermal gradient to achieve crystal growth; S3, crystal directional growth control: In a precisely controlled temperature field, the seed crystal rod and metal crucible are controlled to slowly rotate in opposite directions, gradually pulling the seed crystal rod upward, and adjusting the temperature field to stabilize the growth interface. Through seeding, necking, shoulder release, shoulder reduction, equal diameter growth, and tailing, directional growth of the crystal is achieved; S4, crystal extraction: After the directional growth of the crystal is completed, the pulling speed of the seed crystal rod is reduced to zero, and the heating power is gradually reduced to zero, the crystal is allowed to cool naturally to room temperature, and the metal single crystal is extracted.

2. The method for preparing a metal single crystal according to claim 1, wherein: In step S1, the metal to be prepared is nickel metal, copper metal, iron metal, aluminum metal or titanium alloy metal with a purity of ≥99.99%.

3. The method for preparing a metal single crystal according to claim 1, wherein: In step S2, the seed rod needs to be pre-treated, and the pre-treatment includes surface mechanical polishing and cleaning.

4. The method for preparing a metal single crystal according to claim 1, wherein: In step S3 , the seed rod is pulled upward at a pulling speed of 0.01 to 20 mm / min.

5. The method for preparing a metal single crystal according to claim 1, wherein: In step S3, the rotation speeds of the seed crystal rod and the metal crucible are both 0.01-20 rpm.

6. A metal single crystal preparation device, used to implement the metal single crystal preparation method according to any one of claims 1 to 5, characterized in that: The crucible comprises a metal crucible, an electromagnetic induction coil disposed outside the crucible, an inner heat-insulating cylinder disposed outside the electromagnetic induction coil, an outer heat-insulating cylinder disposed outside the inner heat-insulating cylinder, a seed crystal rod that slides sequentially from top to bottom through the top of the outer heat-insulating cylinder and the top of the inner heat-insulating cylinder and extends into the interior of the metal crucible, and a drive rod that rotatably passes through the bottom of the outer heat-insulating cylinder and the bottom of the inner heat-insulating cylinder from bottom to top; A water cooling jacket for cooling the seed crystal rod is provided at the middle position of the top of the outer heat-insulating cylinder, and a driving component 1 is provided at the top of the seed crystal rod to drive the seed crystal rod to move up and down and rotate; The top end of the driving rod is provided with a crucible tray for supporting the metal crucible, and the bottom end of the driving rod is provided with a driving component 2, and the driving component 2 is provided below the bottom of the outer insulation cylinder; The driving assembly 1 and the driving assembly 2 are respectively used to drive the seed crystal rod and the metal crucible to realize reverse rotation.

7. The metal single crystal preparation device according to claim 6, characterized in that: The driving assembly includes a door-shaped bracket arranged at the top of the outer insulation tube, a telescopic rod arranged at the middle of the top of the door-shaped bracket and a servo motor arranged at the bottom of the telescopic rod. The output shaft of the servo motor is transmission-connected to the seed rod.

8. The metal single crystal preparation device according to claim 7, characterized in that: The telescopic rod is one of an electric telescopic rod, a pneumatic telescopic rod or a hydraulic telescopic rod.

9. The metal single crystal preparation device according to claim 6, characterized in that: The second driving component includes a second servo motor, and the output shaft of the second servo motor is transmission-connected to the driving rod.

10. The metal single crystal preparation device according to claim 6, characterized in that: The bottom of the outer heat-insulating cylinder is provided with supporting legs.

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