Preparation method of metal single crystal seed crystal

Abstract

The invention belongs to the technical field of metal material processing, particularly relates to a preparation method of a metal single crystal seed crystal, and belongs to the technical field of single crystal material preparation and crystal orientation control. The method comprises the following steps: selecting an original seed crystal, heating and melting high-purity metal, carrying out single crystal growth by adopting a czochralski method, carrying out crystal orientation analysis and labeling, directionally cutting out the seed crystal and the like. According to the method, through multiple times of shouldering / necking and X diffraction analysis, natural preferred growth of crystals and clear calibration of later crystal orientation are achieved, crystal orientation control is facilitated, the prepared single crystal metal rod has the large size (the diameter is 3-4 inches, and the length is 300 mm), multiple seed crystals can be obtained through repeated cutting, and the material utilization rate can be increased; the grain boundary and dislocation density is reduced in the continuous crystal orientation selection process, so that the crystal integrity is excellent; seed crystals in various growth directions can be obtained through directional cutting, different process requirements can be met, and the process compatibility is good.

Description

Technical Field

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

[0002] In modern high-end manufacturing, single-crystal metals play a pivotal role, thanks to their unique anisotropic mechanical, thermal, and electrical properties. In aerospace, single-crystal metal blades are used in aircraft engines, where their anisotropic mechanical properties significantly enhance the blades' high-temperature strength and creep resistance, thereby improving engine efficiency and reliability while reducing energy consumption and maintenance costs. In gas turbines, single-crystal metal components, with their excellent high-temperature performance, can withstand higher operating temperatures, enhancing the turbine's power generation efficiency. In the nuclear energy sector, the excellent thermal properties of single-crystal metals contribute to more efficient heat transfer and control. In electronics, their electrical anisotropy provides a critical foundation for the development of high-performance semiconductor devices.

[0003] At present, the preparation methods of metal single crystal seed crystals mainly include directional solidification method, seed selection method, bridge method, etc. The directional solidification method is to control the temperature gradient and solidification rate so that the metal melt solidifies and crystallizes along a specific direction, thereby obtaining a seed crystal with a certain orientation. However, in actual operation, this method is difficult to accurately control the crystal orientation due to the unevenness of the temperature field and flow field, resulting in a large deviation in the crystal orientation, and defects are easily generated during the crystal growth process, affecting the integrity of the crystal. The seed selection method is to select tiny crystals with a specific crystal orientation from polycrystalline materials as seed crystals, but this method relies on suitable crystals naturally existing in polycrystalline materials. The screening process is cumbersome, and it is difficult to ensure the size consistency of the selected seed crystals. At the same time, it is also impossible to effectively control the growth direction of the seed crystals. The bridge method uses a specific mold structure to guide the metal melt to form seed crystals in the bridge area. However, this method has extremely high requirements on the precision of the mold. A slight error in the mold may cause the crystal orientation of the seed crystal to shift and be inconsistent in size. In addition, the preparation process is complicated and the production efficiency is low.

[0004] In summary, the existing methods for preparing metal single crystal seed crystals have significant deficiencies in terms of crystal orientation control accuracy, crystal integrity, and dimensional consistency, making it difficult to meet the stringent requirements of high-end fields for batch preparation of high-consistency metal single crystals. Especially in terms of crystal orientation control, the existing methods are highly dependent on existing ideal seed crystals, lack a systematic and effective preparation and screening mechanism, and are unable to fundamentally ensure the accuracy and stability of the seed crystal orientation. Therefore, the development of an efficient, controllable, and crystal-oriented metal single crystal seed crystal preparation method is of great practical significance and urgent need for improving the consistency and yield of subsequent single crystal preparation and promoting technological development in high-end fields such as aerospace, gas turbines, nuclear energy, and electronic devices. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the existing metal single crystal seed preparation method, such as uncontrollable crystal orientation, poor crystal integrity, and different sizes and directions, and to propose a preparation method for metal single crystal seed with controllable growth, clear crystal orientation selection, and the ability to be cut on demand to obtain different orientations.

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

[0007] A method for preparing a metal single crystal seed crystal comprises the following steps:

[0008] S1, selecting original seed crystal: preparing polycrystalline metal raw material rods as original seed crystals and performing pretreatment;

[0009] S2, heating and melting the high-purity metal: heating the high-purity metal to above the melting point, and melting it in a high-melting-point metal crucible;

[0010] S3, single crystal growth using the Czochralski method: During the single crystal process, shoulder release and necking operations are performed multiple times to encourage the crystal to freely choose a preferred orientation in the neck region, gradually forming a stable single crystal orientation. The crystal diameter and length are controlled to reach the set size, and after cooling, the metal single crystal rod is prepared;

[0011] S4, performing crystal orientation analysis and marking: performing X-ray diffraction crystal orientation analysis on the prepared metal single crystal rod, accurately determining the main crystal orientation of the single crystal and its crystal integrity, and marking the crystal spatial orientation;

[0012] S5, directional cutting of seed crystals: Based on the desired crystal growth direction and the determined crystal orientation as a reference, metal single crystal seed crystals with different orientations are cut out by directional cutting equipment.

[0013] Preferably, in step S1, the pretreatment includes mechanically polishing and cleaning the surface of the original seed crystal.

[0014] Preferably, in step S2, the polycrystalline metal raw material rod is a polycrystalline metal rod with a purity of ≥99.9%.

[0015] Preferably, in step S2, the purity of the high-purity metal is ≥99.9%.

[0016] Preferably, in step S1, the polycrystalline metal raw material rod is a polycrystalline copper rod, a polycrystalline iron rod, a polycrystalline nickel rod or a polycrystalline copper-nickel alloy rod; in step S2, the high-purity metal is copper metal, iron metal, nickel metal or copper-nickel alloy metal, and the high-purity metal corresponds to the metal material of the polycrystalline metal raw material rod, and the high-melting-point metal crucible is one of an iridium crucible, a tungsten crucible and a molybdenum crucible.

[0017] Preferably, in step S3, the crystal diameter is set to 3 to 4 inches, and the length is set to 300 mm.

[0018] The present invention also includes other steps that enable the preparation method of the metal single crystal seed crystal to be used normally, which are all conventional technical means in the art. In addition, the steps not limited in the present invention all adopt conventional technical means in the art.

[0019] The working principle of the present invention:

[0020] This application realizes the natural preferential growth of crystals and the clear calibration of crystal directions in the later stage through multiple shouldering / necking and X-ray diffraction analysis, which is beneficial to the control of crystal directions. The prepared single crystal metal rods have a large size (3 to 4 inches in diameter and 300 mm in length) and can be repeatedly cut to obtain multiple seed crystals, which can improve material utilization; the continuous crystal direction selection process reduces the grain boundary and dislocation density, making the crystal integrity excellent; seed crystals with multiple growth directions can be obtained through directional cutting, which can adapt to different process requirements and has good process compatibility.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This application has the characteristics of controllable crystal orientation, stable size, high crystal quality and good process compatibility. Seed crystals with various growth directions can be obtained through directional cutting to meet different process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a process flow chart of the present invention in the embodiments.

[0024] Figure 2 Schematic diagram of the process of multiple shouldering and necking operations in the embodiment of the present invention.

[0025] Figure 3 Schematic diagram of the process of cutting out a metal single crystal seed crystal according to the present invention in an embodiment. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts conventional purity used in the art.

[0029] The devices used in the present invention are not particularly limited and can be devices commonly used in the art.

[0030] Example 1:

[0031] like Figure 1 As shown, this embodiment proposes a method for preparing a metal single crystal seed crystal, and takes the preparation of a copper single crystal seed crystal in the

[100] direction as an example to illustrate the implementation process of the present invention:

[0032] S1. Take a high-purity polycrystalline copper rod (10×10×100 mm) with a purity of ≥99.9% as the original seed crystal, and then mechanically polish and clean the surface;

[0033] S2. Place copper material with a purity of ≥99.9% in a molybdenum crucible and melt it using induction heating;

[0034] S3, start the straight pulling process, first necking, shrinking the diameter to 5mm and then shouldering to 50mm, then necking to 5mm and continuing to shoulder to 50mm, then repeating this process twice, so that the crystal can freely choose the crystal direction during the necking and shouldering process; control the shouldering to expand to a diameter of about 100mm, and maintain this size to grow to a length of 300mm. After the growth is completed, cool and remove the single crystal copper rod;

[0035] S4. Use an X-ray diffractometer to analyze the crystal orientation of the single crystal rod and calibrate its crystal orientation to

[110] .

[0036] S5. According to the measurement results, cutting is performed perpendicularly at 90° in the

[110] direction, and multiple 10 mm × 10 mm × 100 mm

[100] oriented seed crystals are cut out by wire cutting equipment for subsequent single crystal growth.

[0037] The single crystal seed crystal obtained was sampled at multiple positions for EBSD, which showed that the orientation was

[100] and the electrical conductivity reached 110% IACS (International Annealed Copper Standard).

[0038] Figure 2 In FIG, the process of multiple shouldering and necking operations of the present invention is shown.

[0039] Figure 3 , the process of cutting out a metal single crystal seed crystal according to the present invention is shown.

[0040] Example 2:

[0041] This embodiment proposes a method for preparing a metal single crystal seed crystal, and takes the preparation of a nickel single crystal seed crystal in the

[110] direction as an example to illustrate the implementation process of the present invention:

[0042] S1. Take a high-purity polycrystalline nickel rod (Φ12×100 mm) with a purity of ≥99.99% as the original seed crystal, and then mechanically polish and clean the surface;

[0043] S2. Place nickel material with a purity of ≥99.99% in a tungsten crucible and melt it using induction heating;

[0044] S3, start the straight pulling process, first necking, shrinking the diameter to 4mm and then shouldering to 40mm, then necking to 4mm and continuing to shoulder to 40mm, then repeating this process 3 times, so that the crystal can freely choose the crystal direction during the necking and shouldering process; control the shouldering to expand to a diameter of about 80mm, and maintain this size to grow to a length of 300mm. After the growth is completed, cool and remove the single crystal nickel rod;

[0045] S4. Use an X-ray diffractometer to analyze the crystal orientation of the single crystal nickel rod and calibrate its crystal orientation to

[100] .

[0046] S5. According to the measurement results, cutting is performed at 90° perpendicular to the

[100] direction, and multiple

[110] -oriented seed crystals of Φ12mm×100mm are cut by wire cutting equipment for subsequent single crystal growth.

[0047] The single crystal seed crystal obtained was sampled at multiple positions for EBSD, which showed that the orientation was

[110] and the electrical conductivity reached 22% IACS (International Annealed Copper Standard).

[0048] Example 3:

[0049] This embodiment proposes a method for preparing a metal single crystal seed crystal, and takes the preparation of an iron single crystal seed crystal in the

[111] direction as an example to illustrate the implementation process of the present invention:

[0050] S1. Take a high-purity polycrystalline iron rod (Φ12×100 mm) with a purity of ≥99.99% as the original seed crystal, and then mechanically polish and clean the surface;

[0051] S2. Place iron material with a purity of ≥99.99% in a molybdenum crucible and melt it by induction heating;

[0052] S3, start the straight pulling process, first necking, shrinking the diameter to 4mm and then shouldering to 40mm, then necking to 4mm and continuing to shoulder to 40mm, then repeating this process 3 times, so that the crystal can freely choose the crystal direction during the necking and shouldering process; control the shouldering to expand to a diameter of about 80mm, and maintain this size to grow to a length of 300mm. After the growth is completed, cool and remove the single crystal iron rod;

[0053] S4. Use an X-ray diffractometer to analyze the crystal orientation of the single crystal iron rod and calibrate its crystal orientation to

[100] .

[0054] S5. According to the measurement results, cutting is performed along an angle of 54.74° with the

[100] direction, and multiple Φ12mm×100mm

[111] oriented seed crystals are cut by wire cutting equipment for subsequent single crystal growth.

[0055] The single crystal seed crystal obtained was sampled at multiple positions for EBSD, which showed that the orientation was

[111] and the electrical conductivity reached 17.5% IACS (International Annealed Copper Standard).

[0056] Example 4:

[0057] This embodiment proposes a method for preparing a metal single crystal seed crystal, and takes the preparation of a copper-nickel alloy single crystal seed crystal in the

[111] direction as an example to illustrate the implementation process of the present invention:

[0058] S1. A high-purity polycrystalline copper-nickel alloy rod (12 mm × 12 mm × 100 mm) with a purity of ≥99.99% is taken as a raw seed crystal, and then the surface is mechanically polished and cleaned;

[0059] S2. Place copper-nickel alloy material (brand name CuNi45) with a purity of ≥99.99% in an iridium crucible and melt it by induction heating;

[0060] S3, start the straight pulling process, first necking, shrinking the diameter to 6mm and then shouldering to 60mm, then necking to 6mm and continuing to shoulder to 60mm, then repeating this process 4 times, so that the crystal can freely choose the crystal direction during the necking and shouldering process; control the shouldering to expand to a diameter of about 125mm, and maintain this size to grow to a length of 300mm. After the growth is completed, cool and remove the single crystal copper-nickel alloy rod;

[0061] S4. Use an X-ray diffractometer to analyze the crystal orientation of the single crystal copper-nickel alloy rod and calibrate its crystal orientation to

[100] .

[0062] S5. According to the measurement results, cutting is performed along an angle of 54.74° with the

[100] direction, and multiple Φ12mm×100mm

[111] oriented seed crystals are cut by wire cutting equipment for subsequent single crystal growth.

[0063] The single crystal seed crystal obtained was sampled at multiple positions for EBSD, which showed that the orientation was

[111] and the electrical conductivity reached 2.5% IACS (International Annealed Copper Standard).

[0064] The working principle of the present invention:

[0065] This application realizes the natural preferential growth of crystals and the clear calibration of crystal directions in the later stage through multiple shouldering / necking and X-ray diffraction analysis, which is beneficial to the control of crystal directions. The prepared single crystal metal rods have a large size (3 to 4 inches in diameter and 300 mm in length) and can be repeatedly cut to obtain multiple seed crystals, which can improve material utilization; the continuous crystal direction selection process reduces the grain boundary and dislocation density, making the crystal integrity excellent; seed crystals with multiple growth directions can be obtained through directional cutting, which can adapt to different process requirements and has good process compatibility.

[0066] 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 seed crystal, characterized in that: The following steps are involved: S1, selecting original seed crystal: preparing polycrystalline metal raw material rods as original seed crystals and performing pretreatment; S2, heating and melting the high-purity metal: heating the high-purity metal to above the melting point, and melting it in a high-melting-point metal crucible; S3, single crystal growth using the Czochralski method: During the single crystal process, shoulder release and necking operations are performed multiple times to encourage the crystal to freely choose a preferred orientation in the neck region, gradually forming a stable single crystal orientation. The crystal diameter and length are controlled to reach the set size, and after cooling, the metal single crystal rod is prepared; S4, performing crystal orientation analysis and marking: performing X-ray diffraction crystal orientation analysis on the prepared metal single crystal rod, accurately determining the main crystal orientation of the single crystal and its crystal integrity, and marking the crystal spatial orientation; S5, directional cutting of seed crystals: Based on the desired crystal growth direction and the determined crystal orientation as a reference, metal single crystal seed crystals with different orientations are cut out by directional cutting equipment.

2. The method for preparing a metal single crystal seed crystal according to claim 1, characterized in that: In step S1, the pretreatment includes mechanically polishing and cleaning the surface of the original seed crystal.

3. The method for preparing a metal single crystal seed crystal according to claim 1, wherein: In step S2, the polycrystalline metal raw material rod is a polycrystalline metal rod with a purity of ≥99.9%.

4. The method for preparing a metal single crystal seed crystal according to claim 3, wherein: In step S2, the purity of the high-purity metal is ≥99.9%.

5. The method for preparing a metal single crystal seed crystal according to claim 4, characterized in that: In step S1, the polycrystalline metal raw material rod is a polycrystalline copper rod, a polycrystalline iron rod, a polycrystalline nickel rod or a polycrystalline copper-nickel alloy rod; in step S2, the high-purity metal is copper metal, iron metal, nickel metal or copper-nickel alloy metal, and the high-purity metal corresponds to the metal material of the polycrystalline metal raw material rod, and the high-melting-point metal crucible is one of an iridium crucible, a tungsten crucible, and a molybdenum crucible.

6. The method for preparing a metal single crystal seed crystal according to any one of claims 1 to 5, characterized in that: In step S3, the crystal diameter is set to 3 to 4 inches, and the length is set to 300 mm.

Images