Preparation method of bicrystal test plate seed crystal

Abstract

The invention belongs to the field of processing, and relates to a preparation method of a bicrystal test plate seed crystal, which comprises the following steps: preparing a seed crystal mother block with a specific crystal lattice orientation and an axisymmetric stereo structure from a single crystal raw material; averagely cutting the seed crystal mother block parallel to the symmetry axis of the seed crystal mother block to obtain two seed crystals with the same area and an uncut connecting region; applying a reverse moment to the seed crystals on the two sides of the connection area, breaking the connection area, and obtaining a group of specific fractures on the seed crystals on the two sides of the connection area; and randomly selecting one seed crystal from the mixed packaged and transported seed crystals, screening the other seed crystal which is uniquely matched with the fracture from the residual seed crystals based on the fracture, and pressing the two seed crystals to prepare the double-crystal test plate. The target seed crystal which is uniquely matched with the selected seed crystal and is from the same seed crystal mother block is screened out from a pile of mixed packaged and transported seed crystals, the lattice orientation of the two seed crystals is determined when the double-crystal test plate is prepared through pressing, and the problems that in the prior art, the lattice orientation of the two seed crystals is difficult to determine, and the two seed crystals are prone to inversion are solved.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a method for preparing a twin crystal test plate seed crystal. Background Art

[0002] The small-angle grain boundary performance of single-crystal high-temperature alloys is an important data required for blade engineering applications. In order to obtain the small-angle grain boundary performance of single-crystal high-temperature alloys, it is necessary to prepare a twin crystal test plate with a specific grain boundary orientation difference. The current method is to place two rectangular seed crystals with the same orientation into a mold to press the twin crystal test plate. When placing two rectangular seed crystals, it is necessary to ensure the accuracy of the grain boundary orientation of the two.

[0003] The crystal orientation of single crystal high-temperature alloys can only be detected by microscopic equipment, and the front and back sides are easily reversed when placed in the mold for pressing. If the seed crystal is processed into an asymmetric shape to distinguish the front and back sides, it will lead to an increase in processing costs and cycles, and if the two rectangular seed crystals come from different cutting areas, the orientation difference of the two seed crystals may be inconsistent with the design value. In order to avoid mixing seed crystals from different cutting areas, the rectangular seed crystals in the same cutting area need to be packaged and transported separately. For industrial production and cost considerations, separate packaging and transportation is not feasible. Therefore, mixed transportation increases the difficulty of determining the lattice orientation of the two seed crystals when the mold presses the twin crystal test plate.

[0004] Therefore, how to effectively and cost-effectively avoid the difficulty in determining the lattice orientation of the two seed crystals in the twin crystal test plate and the easy inversion, and ensure the accuracy of the two grain boundary orientations has become an urgent problem to be solved. Summary of the invention

[0005] In view of the above analysis and in view of the deficiencies in the prior art, the present invention aims to provide a method for preparing a twin crystal test plate seed crystal to solve at least one of the problems existing in the prior art, namely, difficulty in determining the lattice orientation of the two seed crystals in the twin crystal test plate and easy inversion.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] The present invention discloses a method for preparing a twin crystal test plate seed crystal, comprising:

[0008] S1. preparing a seed crystal mother block with a specific lattice orientation and an axisymmetric three-dimensional structure from a single crystal raw material;

[0009] S2, cutting the seed crystal mother block evenly parallel to the symmetry axis of the seed crystal mother block to obtain seed crystals and uncut connection areas of equal area, and connecting the two seed crystals through the uncut connection area;

[0010] S3, applying a reverse torque to the seed crystals on both sides of the connection area, rotating the seed crystal mother block perpendicular to the symmetry axis, destroying the connection area, and obtaining a set of specific fractures on the seed crystals on both sides of the connection area. The fractures of the seed crystals on both sides of the connection area can be uniquely matched and meshed, so as to obtain seed crystals that can be mixed packaged and transported;

[0011] S4, randomly select one seed crystal from the mixed packaged and transported seed crystals, select another seed crystal with a unique matching fracture surface from the remaining seed crystals based on the fracture surface, and press the two seed crystals to prepare a twin crystal test plate.

[0012] Preferably, S2 includes cutting the cutting area and thinning the connecting area:

[0013] S201, using a constant speed and voltage to penetrate and cut the cutting area of ​​the seed crystal mother block along the central axis parallel to the long axis direction of the seed crystal mother block:

[0014] S202, reducing the output voltage of the cutting machine to thin the surface of the connection area of ​​the seed crystal mother block.

[0015] Preferably, the cutting in S2 and the thinning of the connection area are performed using a medium-speed wire-cut electrical discharge machine.

[0016] Preferably, the output voltage of the cutting machine in S201 is 50V to 400V, and the cutting speed is 1mm 2 / s~10mm 2 / s.

[0017] Preferably, the output voltage of the cutting machine in S201 is 200V to 400V, and the cutting speed is 3mm 2 / s~6mm 2 / s.

[0018] Preferably, the output voltage of the cutting machine in S202 is 10V to 30V.

[0019] Preferably, destroying the connection region in S3 includes: separating the two seed crystals using a gradually increasing external force.

[0020] Preferably, the external force increases at a fixed rate, and the increasing rate is 1N / s to 50N / s.

[0021] Preferably, determining the lattice orientation of the seed crystal mother block in S1 includes: determining the lattice orientation of the seed crystal mother block based on an angle α between the lattice orientation and the long axis direction of the single crystal raw material, and an angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material.

[0022] Preferably, determining the lattice orientation of the seed crystal mother block in S1 includes: determining the angle γ between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material based on the angle α between the lattice orientation and the long axis direction of the single crystal raw material, and the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material, wherein γ is the lattice orientation of the seed crystal mother block relative to the long axis direction of the seed crystal mother block.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] (1) The present invention retains the connection area when cutting the seed crystals from the seed crystal mother block, and further destroys the connection device to obtain a group of random and specifically matched fractures in the seed crystals on both sides of the connection area, thereby screening out the target seed crystal that is uniquely matched with the selected seed crystal and comes from the same seed crystal mother block from a pile of mixed packaged and transported seed crystals. It is easy to determine the lattice orientation of the two seed crystals when pressing to prepare a twin crystal test plate, thus overcoming the problem of difficulty in determining the lattice orientation of the two seed crystals in the twin crystal test plate in the prior art and easy inversion. At the same time, there is no need for separate packaging and transportation, and the difficulty of determining two seed crystals with the same lattice orientation from mixed seed crystals is reduced.

[0025] (2) The present invention sets the output voltage of the electric spark wire cutting to 50V-400V and the cutting speed to 1mm 2 / s~10mm 2 / s, to achieve a better cutting effect, the thickness of the remelting layer is ≤0.015mm, the cutting surface is flat and free of bubbles, preferably, the thickness of the remelting layer is ≤0.005mm, the grain size of the connecting surface of the twin crystal test plate prepared by the seed crystal is good, it is not easy to grow stray crystals, and the lattice orientation of the two seed crystals meets the design value;

[0026] (3) The present invention can suppress the brittle fracture of the fracture surface by bending and destroying the connection area by increasing the external force at a fixed rate of 1N / s to 50N / s, and can obtain a fracture surface with moderate flatness, no seed crystal material breakage, and good matching when the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is in the range of 0 to 15°;

[0027] (4) The present invention utilizes electric sparks to etch and thin the center of the surface of the connection area, which facilitates subsequent external force to destroy the connection area and reduces the maximum force required for destruction; at the same time, the thinned area can become a fracture generation area, making the fracture more regular and less prone to brittle fracture, thereby improving the accuracy of fracture identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 This is a simplified diagram of the process for preparing the twin crystal test plate seed crystal of the present invention.

[0030] Figure 2 This is the cutting fracture of the seed crystal in Example 1 of the present invention.

[0031] Figure 3 This is the cutting fracture of the seed crystal in Example 2 of the present invention.

[0032] Figure 4 This is the cutting fracture of the seed crystal of Comparative Example 1 of the present invention.

[0033] Figure 5 This is the cutting fracture of the seed crystal of Comparative Example 2 of the present invention.

[0034] Figure 6 This is the twin crystal test plate seed crystal sample prepared in Comparative Example 3 of the present invention.

[0035] Reference numerals:

[0036] Cutting area 01; connecting area 02; break 03; double-direction arrow 001; single-direction arrow 002. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] First of all, it should be noted that the crystal orientation of single-crystal high-temperature alloys can only be detected by microscopic equipment and cannot be identified by the naked eye. This makes it easy for the front and back sides of the rectangular seed crystals to be reversed when two rectangular seed crystals with the same orientation are placed in the mold to press the twin crystal test plate, resulting in failure to obtain the planned grain boundary orientation difference; and processing the seed crystals into an asymmetric shape to distinguish the front and back sides will lead to an increase in processing costs and cycles.

[0039] In addition, when rectangular seed crystals of specific shape and orientation are obtained from seed crystal source blocks by cutting and other means, due to the limitation of cutting tools, the orientations of rectangular seed crystals in different cutting areas may be slightly different. If rectangular seed crystals in different cutting areas are selected to prepare twin crystal test plates, the orientation difference of the two seed crystals may be inconsistent with the design value. However, for industrial production and cost considerations, rectangular seed crystals in the same cutting area are difficult to be packaged and transported separately. Mixed transportation increases the difficulty of determining the lattice orientation of the two seed crystals when the twin crystal test plate is pressed by a mold.

[0040] In addition, due to the uneven heat transfer in different directions of single crystal high-temperature alloys, it is difficult to control the uniformity of the cutting surface and the thickness of the remelted layer when cutting to prepare seed crystals, which in turn affects the accuracy of the lattice orientation of the subsequent twin crystal test plate.

[0041] In view of the above problems, on the one hand, the present invention discloses a method for preparing a twin crystal test plate seed crystal, comprising:

[0042] S1. preparing a seed crystal mother block with a specific lattice orientation and an axisymmetric three-dimensional structure from a single crystal raw material;

[0043] S2, cutting the seed crystal mother block evenly parallel to the symmetry axis of the seed crystal mother block to obtain seed crystals and uncut connection areas of equal area, and connecting the two seed crystals through the uncut connection area;

[0044] S3, applying a reverse torque to the seed crystals on both sides of the connection area, rotating the seed crystal mother block perpendicular to the symmetry axis, destroying the connection area, and obtaining a set of specific fractures on the seed crystals on both sides of the connection area, so that the fractures of the seed crystals on both sides of the connection area can uniquely match and mesh;

[0045] S4, randomly select one seed crystal from the mixed packaged and transported seed crystals, select another seed crystal with a unique matching fracture surface from the remaining seed crystals based on the fracture surface, and press the two seed crystals to prepare a twin crystal test plate.

[0046] A feasible implementation method is:

[0047] A preferred implementation manner is to apply a counterclockwise torque to the seed crystal on one side of the connection area and a clockwise torque to the seed crystal on the other side, and rotate the connection area as the axis of rotation in the direction perpendicular to the symmetry axis of the seed crystal mother block, so that the connection area is broken and destroyed, and the two seed crystals are separated. The residual connection area tissues of the two seed crystals form corresponding fractures; when the fracture surfaces of the two fractures of the seed crystal are recombined, they can be completely matched and connected again, and due to the randomness of the fracture destruction, the fracture of any seed crystal can only be completely matched with the fracture of another seed crystal originally connected to the connection area, but cannot be completely matched with the fracture of any additional seed crystal.

[0048] It can be understood that the present invention retains the connection area when cutting to obtain the seed crystal, and further destroys the connection device to obtain a set of random and specifically matched fractures in the seed crystals on both sides of the connection area. It is easy to screen out the target seed crystal that is uniquely matched with the selected seed crystal and comes from the same seed crystal mother block and is cut in the same cutting area from a pile of mixed packaged and transported seed crystals; when the fractures of a group of screened seed crystals are compounded, the positional relationship of the two seed crystals is consistent with the positional relationship in the seed crystal mother block before cutting, and the lattice orientations on the same side must be the same, thereby providing a basis for placing the two seed crystals when pressing to prepare a twin crystal test plate so that the two seed crystals obtain the target lattice orientation.

[0049] Compared with the prior art, the present invention retains the connection area when cutting seed crystals from a seed crystal mother block, and further destroys the connection device to obtain a group of random and specifically matched fractures in the seed crystals on both sides of the connection area, thereby screening out seed crystals that uniquely match the target seed crystal and come from the same seed crystal mother block from a pile of mixed packaged and transported seed crystals. It is easy to determine the lattice orientation of the two seed crystals when pressing to prepare a twin crystal test plate, overcoming the problem of difficulty in determining the lattice orientation of the two seed crystals in the twin crystal test plate in the prior art and easy inversion.

[0050] It should be noted that single crystal raw materials are often rectangular blocks with a single lattice orientation that are smelted and rolled by a specific process. The seed crystal mother blocks prepared by further division are often also rectangular blocks, and the direction of the four longest sides of the parallel rectangle is defined as the direction of the long axis of the rectangle.

[0051] Regarding the determination of the lattice orientation of the seed crystal mother block in S1, taking the case where the single crystal raw material and the seed crystal mother block are both rectangular blocks, their lattice orientation can be defined by the angle α between the lattice orientation and the long axis direction of the single crystal raw material; the lattice orientation of the seed crystal mother block can be determined by the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material; and the seed crystal mother block is obtained by processing the single crystal raw material, and the angle γ between its long axis direction and the long axis direction of the single crystal raw material is related to α and β, satisfying:

[0052] γ=β-α, wherein -90°≤γ, β, α≤90°, and it is defined that γ, β, α are positive values ​​when rotated clockwise from the long axis direction, and are negative values ​​when rotated counterclockwise from the long axis direction.

[0053] It can be understood that it is easy to obtain the angle α between the lattice orientation and the long axis direction of the single crystal raw material through the existing microscopic characterization means. When the target value of the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is known, it is easy to obtain the angle γ between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material based on the above formula, and then obtain the parameters such as the tool cutting direction for preparing the seed crystal mother block from the single crystal raw material, thereby completing the preparation of the seed crystal mother block.

[0054] Specifically, determining the lattice orientation of the seed crystal mother block in S1 includes: determining the lattice orientation of the seed crystal mother block based on an angle α between the lattice orientation and the long axis direction of the single crystal raw material, and an angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material.

[0055] Specifically, determining the lattice orientation of the seed crystal mother block in S1 includes: determining the angle γ between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material based on the angle α between the lattice orientation and the long axis direction of the single crystal raw material, and the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material, wherein γ is the lattice orientation of the seed crystal mother block relative to the long axis direction of the seed crystal mother block.

[0056] Specifically, the process of cutting the seed crystal mother block and destroying the connection area to obtain the seed crystal in S2-S4 is as follows: Figure 1As shown, the double-direction arrow 001 indicates the long-axis direction of the seed crystal mother block, and the unidirectional arrow 002 indicates the lattice orientation; 01 is the cutting area, 02 is the connecting area, and the shadow indicates the lattice orientation; after the cutting is completed in S2, two independent and equal seed crystals are obtained by separation through S3; after one of the seed crystals is rotated 180° in the long-axis direction, the two seed crystals are pressed together with different lattice orientations.

[0057] It should be noted that if Figure 2 As shown, the seed crystal is provided with a cutting area 01 in the long axis direction thereof, and a working area is provided within the cutting area 01. The working area is the area used for testing after the seed crystal is subsequently used to prepare a twin crystal test plate. The fracture 03 is not within the working area and has no direct impact on the twin crystal test plate detection, but may affect the size of the gap between the two seed crystals of the dual-mode test plate.

[0058] Specifically, S2 includes cutting of the cutting area and thinning of the connecting area:

[0059] S201, using a constant speed and voltage to penetrate and cut the cutting area of ​​the seed crystal mother block along the central axis parallel to the long axis direction of the seed crystal mother block:

[0060] S202, reducing the output voltage of the cutting machine to thin the surface of the connection area of ​​the seed crystal mother block.

[0061] Specifically, a medium-speed wire-cut EDM machine is used for cutting in S2 and thinning of the connection area.

[0062] Specifically, the output voltage of the cutting machine in S201 is 50V to 400V, which can be 55V, 60V, 65V, 70V, 75V, 80V, 100V, 120V, 150V, 180V, 200V, 220V, 250V, 280V, 300V, 320V, 350V, 380V or 400V; the cutting speed is 1mm 2 / s~10mm 2 / s, can be 1mm 2 / s, 2mm 2 / s、3mm 2 / s, 4mm 2 / s, 5mm 2 / s, 6mm 2 / s、7mm 2 / s, 8mm 2 / s, 9mm 2 / s or 10mm 2 / s.

[0063] Preferably, the output voltage of the cutting machine in S201 is 200V to 400V, and the cutting speed is 3mm 2 / s~6mm 2 / s.

[0064] It should be noted that the surface of the seed crystal melts at high temperature during the EDM wire cutting, and the heat provided by the EDM wire cutting is dissipated to the seed crystal. When the two reach a balance, stable melted areas and unmelted areas are formed on the surface of the seed crystal. The melted area cools down to form a remelted layer after the cutting is completed. When the cutting speed is too high, it is difficult to dissipate heat on the surface of the seed crystal and the thickness of the remelted layer increases. When the cutting speed is too low, the accumulated heat on the surface of the seed crystal increases and the thickness of the remelted layer increases.

[0065] The inventors have found that the heat conduction of the seed crystal material in all directions is uneven. The heat can be quickly conducted in the seed crystal orientation direction, and the conduction rate is low in the direction perpendicular to the seed crystal orientation. The angle between the cutting direction and the seed crystal orientation affects the cutting effect and the thickness of the remelting layer, which brings great uncertainty to the seed crystal cutting effect and greatly increases the difficulty of cutting process control. The cutting process proposed by the inventor can obtain a lower remelting layer thickness and better cutting effect when the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is in the range of 0 to 15°, wherein the remelting layer thickness is ≤0.015mm, the cutting surface is flat and free of bubbles, and preferably, the remelting layer thickness is ≤0.005mm.

[0066] Compared with the prior art, the present invention sets the output voltage of the electric spark wire cutting to 50V-400V and the cutting speed to 1mm. 2 / s~10mm 2 / s, achieving a better cutting effect, the remelting layer thickness is ≤0.015mm, the cutting surface is flat and free of bubbles, preferably, the remelting layer thickness is ≤0.005mm; the problem that the uniformity of the cutting surface and the thickness of the remelting layer are difficult to control when cutting and preparing seed crystals in the prior art is solved.

[0067] It should be further explained that the smaller the thickness of the remelted layer, the smoother the cut surface, the better the grain size of the connecting surface of the twin crystal test plate prepared by the seed crystal, the less likely it is to grow impure crystals, and the lattice orientation of the two seed crystals meets the design value, so that accurate small-angle grain boundary performance can be further measured.

[0068] Specifically, in S202, the output voltage of the cutting machine tool is 10V to 30V, which can be 10V, 12V, 15V, 18V, 20V, 22V, 25V, 28V or 30V.

[0069] It should be noted that the thinning process is to use electric sparks to etch and thin the center of the surface of the connection area, so as to facilitate subsequent external force to destroy the connection area and reduce the maximum force required for destruction; at the same time, the thinned area can become the fracture generation area, making the fracture more regular, less prone to brittle fracture, and improving the accuracy of fracture identification.

[0070] Compared with the prior art, the present invention utilizes electric sparks to etch and thin the center of the surface of the connection area, making it easier for subsequent external forces to destroy the connection area and reducing the maximum force required for destruction; at the same time, the thinned area can become a fracture generation area, making the fracture more regular, less prone to brittle fracture, and improving the accuracy of fracture identification.

[0071] It should be noted that regarding the external force application area in S3, the seed crystal areas on both sides of the connection area are non-working areas, and the application of external force will not affect the seed crystal working area.

[0072] Specifically, destroying the connection region in S3 includes: separating the two seed crystals by using a gradually increasing external force.

[0073] Preferably, the external force increases at a fixed rate, and the optional range of the increase rate is 1N / s to 50N / s, which can be 1N / s, 3N / s, 5N / s, 8N / s, 10N / s, 12N / s, 15N / s, 18N / s, 20N / s, 22N / s, 24N / s, 25N / s, 28N / s, 30N / s, 33N / s, 35N / s, 38N / s, 40N / s, 42N / s, 45N / s, 48N / s, and 50N / s.

[0074] The inventors found that when metal materials are bent, the bending area will generate heat due to the force, which improves the plasticity of the metal material and reduces the occurrence of brittle fractures; large external forces can easily lead to brittle fractures while increasing the temperature and material plasticity of the bending area, so the increase in external forces has an uncertain effect on the bending of seed crystal materials; at the same time, the heat conduction in all directions of the seed crystal material is uneven, and the heat can be quickly conducted in the seed crystal orientation direction, and the conduction rate is low in the direction perpendicular to the seed crystal orientation. The angle between the bending direction and the seed crystal orientation affects the fracture flatness and bending effect, which greatly increases the process control difficulty of separating seed crystals to obtain a fracture with a flat cross-section and a certain roughness that meets the matching requirements. The bending separation process proposed by the inventor can obtain a fracture with moderate flatness, no seed crystal material fragmentation, and good matching when the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is in the range of 0 to 15°.

[0075] Compared with the prior art, the present invention can suppress the brittle fracture of the fracture by bending and destroying the connection area with an external force increasing at a fixed rate of 1N / s to 50N / s, and can obtain a fracture with moderate flatness, no seed crystal material breakage and good matching when the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is in the range of 0 to 15°.

[0076] Specifically, in S4, selecting another seed crystal with a uniquely matched fracture surface from the remaining seed crystals based on the fracture surface includes:

[0077] S401: selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the first seed crystal;

[0078] S402: selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the second seed crystal;

[0079] S403: Try to match the fracture surfaces of the first seed crystal and the second seed crystal to determine whether the fracture surface of the second seed crystal completely matches the fracture surface of the first seed crystal;

[0080] If the fracture surfaces of the two crystals are completely matched, the second crystal is the target crystal of the first crystal, and the two crystals can be used as raw materials for making twin crystal plates.

[0081] If the fracture surfaces of the two seeds do not completely match, a seed crystal with no wear and clear lines on the fracture surface is selected from the remaining mixed packaged and transported seed crystals as the third seed crystal, and the above fracture surface matching process is repeated to determine whether the fracture surface of the third seed crystal completely matches that of the first seed crystal;

[0082] ...repeat the above steps until the target seed crystal of the first seed crystal is obtained.

[0083] Specifically, in S4, two seed crystals are pressed to prepare a twin crystal test plate, including:

[0084] S411: arranging two seed crystals in different lattice orientations and placing them in abutment in a mold;

[0085] S412: Pressing the twin crystal test plate wax model in the twin crystal test plate mold.

[0086] Specifically, the pressing conditions of S412 are a pressure of 1 bar to 10 bar and a temperature of 60 to 80°C.

[0087] Specifically, the wax model raw material is low melting point wax.

[0088] In order to better illustrate the present invention, the following embodiments are further provided:

[0089] Example 1

[0090] This embodiment discloses a method for preparing a double crystal test plate seed crystal, comprising:

[0091] S1. preparing a seed crystal mother block with a specific lattice orientation and an axisymmetric three-dimensional structure from a single crystal raw material;

[0092] Among them, the single crystal raw material is single crystal high temperature alloy DD5, the lattice orientation can be determined by the lattice orientation and the long axis direction of the single crystal raw material at an angle α=5°, the seed crystal mother block lattice orientation can be determined by the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material at an angle β=15°, and the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material at an angle γ=10°.

[0093] S2, cutting the seed crystal mother block evenly parallel to the symmetry axis of the seed crystal mother block to obtain seed crystals and uncut connection areas of equal area, and connecting the two seed crystals through the uncut connection area;

[0094] S201, using a constant speed and voltage to penetrate the cutting area of ​​the seed crystal mother block along the central axis parallel to the long axis of the seed crystal mother block: the output voltage of the cutting machine in S201 is 200V; the cutting speed is 5mm 2 / s;

[0095] S202, reducing the output voltage of the cutting machine to thin the surface of the connection area of ​​the seed crystal mother block; the output voltage of the cutting machine in S202 is 20V.

[0096] The cut surface was inspected according to standard HB / Z 20053. The inspection result showed that the thickness of the remelted layer was 0.005mm. Figure 2 ;

[0097] S3. Apply reverse torque to the seed crystals on both sides of the connection area, rotate perpendicular to the symmetry axis of the seed crystal mother block, destroy the connection area, and obtain a set of specific fractures on the seed crystals on both sides of the connection area. The fractures of the seed crystals on both sides of the connection area can be uniquely matched and meshed to obtain seed crystals that can be mixed packaged and transported; the external force increases at a fixed rate of 5N / s.

[0098] The fracture surface is tested to be flat, and the two fracture surfaces can be completely recombined. After the two fracture surfaces are recombined, the two seed crystals cannot be displaced in the direction parallel to the fracture surface.

[0099] S4, randomly select one seed crystal from the mixed packaged and transported seed crystals, select another seed crystal with a unique matching fracture surface from the remaining seed crystals based on the fracture surface, and press the two seed crystals to prepare a twin crystal test plate.

[0100] S401, selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the first seed crystal;

[0101] S402, selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the second seed crystal;

[0102] S403, trying to match the fracture surfaces of the first seed crystal and the second seed crystal, and determining whether the fracture surface of the second seed crystal completely matches the fracture surface of the first seed crystal;

[0103] If the fracture surfaces of the two crystals are completely matched, the second crystal is the target crystal of the first crystal, and the two crystals can be used as raw materials for making twin crystal plates.

[0104] If the fracture surfaces of the two seeds do not completely match, a seed crystal with no wear and clear lines on the fracture surface is selected from the remaining mixed packaged and transported seed crystals as the third seed crystal, and the above fracture surface matching process is repeated to determine whether the fracture surface of the third seed crystal completely matches that of the first seed crystal;

[0105] …repeat the above steps until the target seed crystal of the first seed crystal is obtained;

[0106] S404, arranging two seed crystals in different lattice orientations and placing them in abutment in a mold;

[0107] S405, pressing the twin crystal test plate wax mold in the twin crystal test plate mold at a pressure of 7 bar and a temperature of 68°C.

[0108] Example 2

[0109] This embodiment discloses a method for preparing a double crystal test plate seed crystal, comprising:

[0110] S1. preparing a seed crystal mother block with a specific lattice orientation and an axisymmetric three-dimensional structure from a single crystal raw material;

[0111] Among them, the single crystal raw material is single crystal high temperature alloy DD6, the lattice orientation can be determined by the lattice orientation and the long axis direction of the single crystal raw material at an angle α=8°, the seed crystal mother block lattice orientation can be determined by the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material at an angle β=10°, and the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material at an angle γ=2°.

[0112] S2, cutting the seed crystal mother block evenly parallel to the symmetry axis of the seed crystal mother block to obtain seed crystals and uncut connection areas of equal area, and connecting the two seed crystals through the uncut connection area;

[0113] S201, using a constant speed and voltage to penetrate the cutting area of ​​the seed crystal mother block along the central axis parallel to the long axis of the seed crystal mother block: the output voltage of the cutting machine in S201 is 100V; the cutting speed is 8mm 2 / s;

[0114] S202, reducing the output voltage of the cutting machine to thin the surface of the connection area of ​​the seed crystal mother block; the output voltage of the cutting machine in S202 is 10V.

[0115] According to the standard HB / Z-20053, the cutting surface was inspected and the inspection results showed that the thickness of the remelted layer was 0.014mm. Figure 3 ;

[0116] S3. Apply reverse torque to the seed crystals on both sides of the connection area, rotate perpendicular to the symmetry axis of the seed crystal mother block, destroy the connection area, and obtain a set of specific fractures on the seed crystals on both sides of the connection area. The fractures of the seed crystals on both sides of the connection area can be uniquely matched and meshed to obtain seed crystals that can be mixed packaged and transported; the external force increases at a fixed rate of 20N / s.

[0117] The detection shows that the fracture surface has slight fluctuations, which does not affect the placement of the seed crystal in the mold, and the two fracture surfaces can be completely compounded. After the two fracture surfaces are compounded, the two seed crystals cannot be displaced in the direction parallel to the fracture surface.

[0118] S4, randomly select one seed crystal from the mixed packaged and transported seed crystals, select another seed crystal with a unique matching fracture surface from the remaining seed crystals based on the fracture surface, and press the two seed crystals to prepare a twin crystal test plate.

[0119] S401, selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the first seed crystal;

[0120] S402, selecting a seed crystal with no wear on the fracture and clear lines from the mixed packaged and transported seed crystals as the second seed crystal;

[0121] S403, trying to match the fracture surfaces of the first seed crystal and the second seed crystal, and determining whether the fracture surface of the second seed crystal completely matches the fracture surface of the first seed crystal;

[0122] If the fracture surfaces of the two crystals are completely matched, the second crystal is the target crystal of the first crystal, and the two crystals can be used as raw materials for making twin crystal plates.

[0123] If the fracture surfaces of the two seeds do not completely match, a seed crystal with no wear and clear lines on the fracture surface is selected from the remaining mixed packaged and transported seed crystals as the third seed crystal, and the above fracture surface matching process is repeated to determine whether the fracture surface of the third seed crystal completely matches that of the first seed crystal;

[0124] …repeat the above steps until the target seed crystal of the first seed crystal is obtained;

[0125] S404, arranging two seed crystals in different lattice orientations and placing them in abutment in a mold;

[0126] S405, pressing the twin crystal test plate wax mold in the twin crystal test plate mold at a pressure of 7 bar and a temperature of 68°C.

[0127] Comparative Example 1

[0128] This comparative example discloses a method for preparing a twin crystal test plate seed crystal, which is different from Example 1 in that the cutting speed of the medium-speed wire EDM wire cutting machine is about 20 mm 2 / s is significantly greater than the cutting speed protected by the present invention.

[0129] The cutting section inspection results show that the remelting layer thickness is 0.035mm and there are bubbles. Figure 4 .

[0130] Comparative Example 2

[0131] This comparative example discloses a method for preparing a twin crystal test plate seed crystal, which is different from Example 1 in that the cutting speed of the medium-speed wire EDM wire cutting machine is about 0.1 mm 2 / s is significantly smaller than the cutting speed protected by the present invention.

[0132] The cutting section inspection results show that the thickness of the remelted layer is 0.022mm. Figure 5 , and the cutting time of each seed crystal is as long as 12 minutes, which cannot be applied in engineering.

[0133] Comparative Example 3

[0134] This comparative example discloses a method for preparing a twin crystal test plate seed crystal, which is different from Example 1 in that 500N (sufficiently large constant force) is used to instantly separate the seed crystals into two seed crystals.

[0135] The fracture inspection results of the connection area show that some seed crystals are deformed near the fracture, which affects the placement of the seed crystal in the mold. Figure 6 As shown, due to the deformation of the fracture, there is a gap in the connection surface of the working area, which causes the connection surface of the working areas of the two seed crystals in the final double crystal test plate to be bent and uneven.

[0136] Comparative Example 4

[0137] This comparative example discloses a method for preparing a twin crystal test plate seed crystal, which differs from Example 1 in that: a force is increased at a speed of 0.1 N / s to slowly separate the seed crystals into two seed crystals, and 0.1 N / s is significantly smaller than the protection range of the force increase rate of the present invention.

[0138] The fracture inspection results of the connecting area showed that the fracture was smooth and did not affect the placement of the seed crystal in the mold; after the two fractures were combined, the two seed crystals could be displaced in parallel to the fracture direction, and the fractures of the two seed crystals did not play a matching role and did not have a unique pairing characteristic, so a unique pair of seed crystals could not be screened out from the mixed packaged and transported seed crystals; and the process of separating the seed crystals in this comparative example took as long as 2 minutes and could not be applied in engineering.

[0139] From the above examples and comparative test results, it can be seen that the present invention sets the output voltage of the electric spark wire cutting to 50V-400V and the cutting speed to 1mm 2 / s~10mm 2 / s, to achieve a better cutting effect, the thickness of the remelting layer is ≤0.015mm, the cutting surface is flat and free of bubbles, preferably, the thickness of the remelting layer is ≤0.005mm; the present invention can suppress the brittle fracture of the fracture by increasing the external force at a fixed rate of 1N / s to 50N / s to bend and destroy the connecting area, and can obtain a fracture with moderate flatness, no seed crystal material breakage and good matching when the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material is in the range of 0 to 15°.

[0140] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a twin crystal test plate seed crystal, characterized in that: include: S1. preparing a seed crystal mother block with a specific lattice orientation and an axisymmetric three-dimensional structure from a single crystal raw material; S2, cutting the seed crystal mother block evenly parallel to the symmetry axis of the seed crystal mother block to obtain seed crystals and uncut connection areas of equal area, and connecting the two seed crystals through the uncut connection area; S3, applying a reverse torque to the seed crystals on both sides of the connection area, rotating the seed crystal mother block perpendicular to the symmetry axis, destroying the connection area, and obtaining a set of specific fractures on the seed crystals on both sides of the connection area. The fractures of the seed crystals on both sides of the connection area can be uniquely matched and meshed, so as to obtain seed crystals that can be mixed packaged and transported; S4, randomly select one seed crystal from the mixed packaged and transported seed crystals, select another seed crystal with a unique matching fracture surface from the remaining seed crystals based on the fracture surface, and press the two seed crystals to prepare a twin crystal test plate.

2. The method for preparing a twin crystal test plate seed crystal according to claim 1, characterized in that: S2 includes cutting of the cutting area and thinning of the connecting area: S201, using a constant speed and voltage to penetrate and cut the cutting area of ​​the seed crystal mother block along the central axis parallel to the long axis direction of the seed crystal mother block: S202, reducing the output voltage of the cutting machine to thin the surface of the connection area of ​​the seed crystal mother block.

3. The method for preparing a twin crystal test plate seed crystal according to claim 2, characterized in that: S2 cutting and thinning of the connection area use a medium-speed wire EDM machine.

4. The method for preparing a twin crystal test plate seed crystal according to claim 3, characterized in that: The output voltage of the cutting machine in S201 is 50V~400V, and the cutting speed is 1mm 2 / s~10mm 2 / s.

5. The method for preparing a twin crystal test plate seed crystal according to claim 4, characterized in that: The output voltage of the cutting machine in S201 is 200V~400V, and the cutting speed is 3mm 2 / s~6mm 2 / s.

6. The method for preparing a twin crystal test plate seed crystal according to claim 3, characterized in that: The output voltage of the cutting machine in S202 is 10V~30V.

7. The method for preparing a twin crystal test plate seed crystal according to claim 1, characterized in that: Destroying the connection region in S3 includes: separating the two seed crystals using a gradually increasing external force.

8. The method for preparing a twin crystal test plate seed crystal according to claim 7, characterized in that: The external force increases at a fixed rate of 1N / s to 50N / s.

9. The method for preparing a twin crystal test plate seed crystal according to any one of claims 1 to 8, characterized in that: Determining the lattice orientation of the seed crystal mother block in S1 includes: determining the lattice orientation of the seed crystal mother block based on an angle α between the lattice orientation and the long axis direction of the single crystal raw material, and an angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material.

10. The method for preparing a twin crystal test plate seed crystal according to claim 9, characterized in that: Determining the lattice orientation of the seed crystal mother block in S1 includes: determining the angle γ between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material based on the angle α between the lattice orientation and the long axis direction of the single crystal raw material, and the angle β between the long axis direction of the seed crystal mother block and the long axis direction of the single crystal raw material, wherein γ is the lattice orientation of the seed crystal mother block relative to the long axis direction of the seed crystal mother block.

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