A method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy

Abstract

The application discloses a preparation method of a titanium-aluminum alloy unidirectional lamellar structure and relates to the technical field of titanium-aluminum alloy lamellar orientation regulation, which is used to solve the technical problems that the existing titanium-aluminum alloy is difficult to control in unidirectional lamellar structure and the preparation process is complex. The preparation method comprises two steps of heat preservation treatment and directional drawing. In the strong magnetic field, the titanium-aluminum alloy is subjected to heat preservation treatment above the alpha phase transition temperature, an additional magnetic driving force is applied by the strong magnetic field to make the alpha phase <0001> orientation grain preferentially grow in the direction perpendicular to the magnetic field, then the drawing is carried out at a certain speed, the preferentially grown alpha grains grow against the heat flow direction due to the relative downward heat flow during the drawing, and the lamellar structure obtained is cooled to room temperature, so that the lamellar structure orientation is close to parallel to the magnetic field direction.

Description

Technical Field

[0001] This invention relates to the field of titanium-aluminum alloy lamellar orientation control technology, and in particular to a method for preparing a unidirectional lamellar structure of titanium-aluminum alloy. Background Technology

[0002] Titanium-aluminum alloy is a novel lightweight high-temperature structural material with broad application prospects in aerospace, military, and automotive engine fields. It possesses excellent properties such as low density, high specific strength, high specific stiffness, good oxidation resistance, creep resistance, fatigue resistance, and good flame retardancy. It is the most promising alternative to nickel-based superalloys in the 650–900℃ service range, achieving a weight reduction of 40–50%, thereby significantly improving equipment performance. Research shows that when the α2 / γ lamellar microstructure of titanium-aluminum alloy has a consistent orientation, not only is the strength-ductility match optimal, but creep resistance is also improved, giving it significant advantages in high-temperature environments, especially for components subjected to uniaxial stress, such as engine blades. The lamellae in titanium-aluminum alloy are formed during the α→α2+γ solid-state phase transformation, and α and γ follow {0001} α / / {111} γ , <11-20> α / / <110> γ The Blackburn orientation relationship has a unique habit plane. Therefore, the crystal orientation of the α phase determines the lamellar orientation.

[0003] In recent years, researchers both domestically and internationally have proposed numerous methods and conducted extensive research on this issue, including seed crystal methods, directional solidification, thermomechanical processing, and directional heat treatment. The seed crystal method utilizes pre-prepared seed crystals with specific orientations and structures as guides, allowing the melt to grow along the seed crystal's orientation during solidification, thus obtaining a unidirectional lamellar structure. However, currently, there are few suitable titanium-aluminum alloy seed crystals, mainly in the Ti-Al-Si system, which significantly limits the application of the seed crystal method. Due to the controllability of heat flow direction and solidification parameters, directional solidification technology is often used to prepare single-crystal materials. During solidification, the first precipitated phase is controlled to be the all-β phase. Based on the phase relationship, the β→α phase transformation process is controlled to achieve the purpose of controlling the lamellar orientation. However, during solidification, 0° lamellae are gradually replaced by 45° lamellae during growth. Furthermore, numerous research results indicate that controlling the crystal orientation of the high-temperature α phase in titanium-aluminum alloys can achieve lamellar structure orientation control, including thermomechanical processing and directional heat treatment. Based on the theory of preferred nucleation and growth of α recrystallization, hot extrusion in the α single-phase region forms a fibrous texture of {0001} / / ED (extrusion direction), increasing the proportion of α2 / γ lamellae parallel to the extrusion direction to 60%. Under the action of directional heat flow and directional pulling of the specimen, a curved interface is formed between the competing growing grains. Due to the generation of additional pressure, atoms on both sides of the curved interface undergo directional diffusion, causing directional migration of the grain boundaries. Ultimately, 41% of the lamellae are parallel to the growth direction of the columnar crystals. However, due to the low room temperature plasticity of titanium-aluminum alloys, defects such as pores and cracks are easily formed during hot working, resulting in low material utilization. It is evident that existing methods for preparing lamellae structures of titanium-aluminum alloys suffer from the technical problems of difficulty in controlling unidirectional lamellae structures and complex preparation processes. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a unidirectional lamellar structure of titanium-aluminum alloys, which solves the technical problems of existing methods for preparing unidirectional lamellar structures being difficult to control and having complex preparation processes. In view of this, this invention is achieved through the following solution.

[0005] In a first aspect, the present invention provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy. Under strong magnetic field conditions, the titanium-aluminum alloy is held at a temperature above its α-phase transformation temperature, and an additional magnetic driving force is applied by a strong magnetic field to induce the α-phase transformation. <0001> Grains oriented perpendicular to the magnetic field direction are preferentially grown and then pulled at a certain rate. Due to the relatively downward heat flow during the pulling process, the preferentially grown α grains grow against the direction of the heat flow. After cooling to room temperature, the resulting lamellar structure is oriented nearly parallel to the magnetic field direction.

[0006] Compared with existing technologies, this invention introduces a strong magnetic field condition into the preparation method of unidirectional lamellar structure of titanium-aluminum alloy. During the heat treatment of titanium-aluminum alloy above its α-phase transformation temperature, the magnetic driving force applied to the titanium-aluminum alloy by the strong magnetic field induces the α-phase of the titanium-aluminum alloy. <0001> Grains with a preferred orientation perpendicular to the magnetic field direction grow preferentially, forming a preferred orientation of the α phase. During directional pulling, the preferredly oriented α phase can grow against the heat flow, resulting in a unidirectional lamellar structure of titanium-aluminum alloy during subsequent cooling. The technical solution of this invention can precisely control the formation of a unidirectional lamellar structure of titanium-aluminum alloy by controlling the magnetic field strength, holding temperature, holding time, and pulling rate. It is convenient to operate and has a simple process, solving the technical problems of existing methods for preparing unidirectional lamellar structures of titanium-aluminum alloys, which suffer from difficulty in controlling the unidirectional lamellar structure and complex preparation processes.

[0007] Furthermore, the method for preparing the unidirectional lamellar structure of the titanium-aluminum alloy of the present invention includes:

[0008] Obtain titanium-aluminum alloy billets, including cast titanium-aluminum alloys, powder hot isostatic pressing titanium-aluminum alloys, and wrought titanium-aluminum alloys;

[0009] The titanium-aluminum alloy blank is machined into a cylinder with a diameter of 4-8mm, and the wire cutting marks on the sample are ground off.

[0010] The titanium-aluminum alloy is installed on the pull rod of the equipment and subjected to heat treatment in a strong magnetic field and vacuum environment for 20-90 minutes; wherein the heat treatment temperature is higher than the α-phase transformation temperature of the titanium-aluminum alloy.

[0011] After the heat preservation treatment, directional pulling is performed. After the pulling is completed, the sample surface temperature drops below 100℃, the sample is taken out, and after cooling, a unidirectional lamellar structure of titanium-aluminum alloy is obtained; wherein the magnetic field direction is parallel and opposite to the pulling direction.

[0012] Furthermore, the method for preparing the unidirectional lamellar structure of titanium-aluminum alloy of the present invention includes two steps: heat preservation treatment at a specified magnetic field strength and temperature, and subsequent directional pulling.

[0013] Furthermore, in the method for preparing the unidirectional lamellar structure of titanium-aluminum alloy of the present invention, the strength of the magnetic field is greater than or equal to 5T.

[0014] Furthermore, in the method for preparing the unidirectional lamellar structure of the titanium-aluminum alloy of the present invention, after heat preservation treatment, the titanium-aluminum alloy is subjected to directional drawing, including:

[0015] The direction of the magnetic field is parallel to and opposite to the direction of the pull;

[0016] During the directional pulling process, a relatively downward heat flow is maintained.

[0017] Furthermore, in the method for preparing the unidirectional lamellar structure of titanium-aluminum alloy of the present invention, the directional pulling rate is less than or equal to 20 μm / s.

[0018] Furthermore, in the method for preparing the unidirectional lamellar structure of the titanium-aluminum alloy of the present invention, after the drawing is completed, a unidirectional α2 / γ lamellar structure is formed during the cooling process.

[0019] Furthermore, in the method for preparing a unidirectional lamellar structure of titanium-aluminum alloy of the present invention, after the pulling is completed, waiting for the sample surface temperature to drop below 100°C includes:

[0020] After the titanium-aluminum alloy is directionally pulled, and the surface temperature of the sample is reduced to below 100°C, a unidirectional lamellar structure of the titanium-aluminum alloy is obtained.

[0021] Secondly, the present invention provides a unidirectional lamellar structure of a titanium-aluminum alloy, which is prepared by the above-mentioned method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy.

[0022] Compared with the prior art, the preparation method of the present invention is novel, the equipment is easy to operate, the process is simple, and the preparation method of the titanium-aluminum alloy unidirectional lamellar structure has significant effects. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 This is a schematic diagram of the titanium-aluminum alloy lamellar structure of Embodiment 1 of the present invention;

[0025] Figure 2 This is a schematic diagram of the titanium-aluminum alloy lamellar structure in Embodiment 2 of the present invention;

[0026] Figure 3 This is a schematic diagram of the titanium-aluminum alloy lamellar structure in Embodiment 3 of the present invention;

[0027] Figure 4 This is a schematic diagram of the α-phase crystal orientation of the titanium-aluminum alloy lamellar structure in Embodiment 3 of the present invention;

[0028] Figure 5 This is a schematic diagram of the titanium-aluminum alloy lamellar structure in Embodiment 4 of the present invention;

[0029] Figure 6 This is a schematic diagram of the titanium-aluminum alloy lamellar structure of Comparative Example 1 of the present invention;

[0030] Figure 7 This is a schematic diagram of the strong magnetic field directional heat treatment equipment and a schematic diagram of sample placement according to the present invention. Detailed Implementation

[0031] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0032] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0033] Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise expressly and specifically defined. "Several" means one or more, unless otherwise expressly and specifically defined.

[0034] Existing methods for controlling the lamellar orientation of TiAl alloys mainly include seed crystal method, directional solidification method, directional heat treatment method, and thermomechanical processing. The seed crystal method utilizes pre-prepared seed crystals with specific orientations and structures as guides, allowing the melt to grow along the seed crystal's orientation during solidification, thus obtaining a unidirectional lamellar structure. However, currently, there are few TiAl alloy seed crystals that meet the requirements, mainly in the Ti-Al-Si system, which greatly limits the application of the seed crystal method. Due to the controllability of heat flow direction and solidification parameters, directional solidification technology is often used to prepare single-crystal materials. The key to this method is controlling the first precipitated phase to be the all-β phase during solidification. Based on the phase relationship, the β→α phase transformation process is controlled to achieve the purpose of controlling the lamellar orientation. However, during solidification, 0° lamellae are gradually replaced by 45° lamellae during growth. Furthermore, directional heat treatment and hot extrusion are based on the formation of α-preferred orientation, thereby achieving control of lamellar orientation. However, due to the low room temperature plasticity of titanium-aluminum alloys, defects such as pores and cracks are easily formed during hot working, resulting in low material utilization. It is evident that existing methods for preparing lamellar structures of titanium-aluminum alloys suffer from technical problems, such as difficulty in controlling unidirectional lamellar structures and complex preparation processes.

[0035] To address the aforementioned technical problems, in a first aspect, the present invention provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy. Under strong magnetic field conditions, the titanium-aluminum alloy is held at a temperature above its α-phase transformation temperature, and an additional magnetic driving force is applied using a strong magnetic field to induce the α-phase... <0001> Grains oriented perpendicular to the magnetic field direction are preferentially grown and then pulled at a certain rate. Due to the relatively downward heat flow during the pulling process, the preferentially grown α grains grow against the direction of the heat flow. After cooling to room temperature, the resulting lamellar structure is oriented nearly parallel to the magnetic field direction.

[0036] Using the above technical solution, in the method for preparing a unidirectional lamellar structure of titanium-aluminum alloy of the present invention, during the heat treatment of titanium-aluminum alloy above its α-phase transformation temperature, the α-phase of the titanium-aluminum alloy is induced by the magnetic driving force applied to the titanium-aluminum alloy by a strong magnetic field. <0001> Grains with a preferred orientation perpendicular to the magnetic field direction grow preferentially, forming a preferred orientation of the α phase. During directional pulling, the preferredly oriented α phase can grow against the heat flow, resulting in a unidirectional lamellar structure of titanium-aluminum alloy during subsequent cooling. The technical solution of this invention can precisely control the formation of a unidirectional lamellar structure of titanium-aluminum alloy by controlling the magnetic field strength, holding temperature, holding time, and pulling rate. It is convenient to operate and has a simple process, solving the technical problems of existing methods for preparing unidirectional lamellar structures of titanium-aluminum alloys, which suffer from difficulty in controlling the unidirectional lamellar structure and complex preparation processes.

[0037] As one possible implementation, the method for preparing a unidirectional lamellar structure of titanium-aluminum alloy according to the present invention includes:

[0038] Obtain titanium-aluminum alloy billets, including cast titanium-aluminum alloys, powder hot isostatic pressing titanium-aluminum alloys, and wrought titanium-aluminum alloys;

[0039] The titanium-aluminum alloy blank is machined into a cylinder with a diameter of 4-8mm, and the wire cutting marks on the sample are ground off.

[0040] The titanium-aluminum alloy is installed on the pull rod of the equipment and subjected to heat treatment in a strong magnetic field and vacuum environment for 20-90 minutes; wherein the heat treatment temperature is higher than the α-phase transformation temperature of the titanium-aluminum alloy.

[0041] After the heat preservation treatment, directional pulling is performed. After the pulling is completed, the sample surface temperature drops below 100℃, the sample is taken out, and after cooling, a unidirectional lamellar structure of titanium-aluminum alloy is obtained; wherein the magnetic field direction and the pulling direction are parallel and opposite.

[0042] Using the above technical solution, in the method for preparing a unidirectional lamellar structure of titanium-aluminum alloy of the present invention, during the heat treatment of titanium-aluminum alloy above its α-phase transformation temperature, the α-phase of the titanium-aluminum alloy is induced by the magnetic driving force applied to the titanium-aluminum alloy by a strong magnetic field. <0001> Grains preferentially grow in the direction perpendicular to the magnetic field, leading to a preferred orientation of the α-phase. During directional pulling, the preferredly oriented α-phase can grow against the direction of heat flow, resulting in a unidirectional lamellar structure of titanium-aluminum alloy during subsequent cooling. The vacuum environment protects the heating element and the titanium-aluminum alloy from oxidation during the process, ensuring the cleanliness of the material surface and the purity of the internal structure, which is beneficial for forming a high-quality unidirectional lamellar structure of titanium-aluminum alloy.

[0043] It should be understood that in the preparation method of the titanium-aluminum alloy unidirectional lamellar structure of the present invention, in order to further improve the preparation efficiency of the titanium-aluminum alloy unidirectional lamellar structure, it is also necessary to control the magnetic field strength, pulling rate and holding time. For example, the pulling rate can be less than or equal to 20 μm / s, the magnetic field strength can be greater than or equal to 5 T, and the holding time can be 20 min to 90 min. In another example, the pulling rate can be 20 μm / s, 15 μm / s, 10 μm / s or 5 μm / s, the magnetic field strength can be 5 T, 7 T, 9 T or 10 T, and the holding time can be 20 min, 30 min, 60 min or 90 min.

[0044] Secondly, the present invention provides a unidirectional lamellar structure of a titanium-aluminum alloy, which is prepared by the above-mentioned method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy.

[0045] Compared with the prior art, the preparation method of the present invention is novel, the equipment is easy to operate, the process is not complicated, and the preparation method of the titanium-aluminum alloy unidirectional lamellar structure has significant effects.

[0046] To better understand the present invention, the following specific embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0047] Unless otherwise specified, all raw materials used in the following examples are commercially available. Example 1

[0048] This embodiment provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, including:

[0049] S100, using wire cutting, cut the cast Ti-43Al-0.7Fe alloy into samples with dimensions of Φ4×100mm. Place the sample on the pull rod, and raise the pull rod to evacuate to a vacuum level of 3×10⁻⁶. -2 Pa;

[0050] S200, set the heat treatment temperature of the device to 1350℃ and the magnetic field strength to 5T. The temperature is increased from room temperature according to a fixed heating program, and the excitation program is started at the same time. When the temperature and magnetic field strength reach the set values ​​at the same time, the temperature is held for 20 minutes. Then the pulling is performed at a pulling speed of 10μm / s and a pulling distance of 30mm. After the pulling is completed, the sample is taken out when the sample surface cools to 100℃.

[0051] S300, polishing the cross section of the sample parallel to the magnetic field direction: first polish with SiC sandpaper to 2000#, then electropolish with an electrolyte of 60% methanol + 35% n-butanol + 5% perchloric acid, voltage 35V, time 25s, electrolyte temperature less than or equal to 10℃. After polishing, place it in an ultrasonic bath, clean it with alcohol and air dry it. Characterize its microstructure with an optical microscope.

[0052] After obtaining the unidirectional lamellar structure of the titanium-aluminum alloy in this embodiment, its microstructure was characterized using an optical microscope. The characterization results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the Ti-43Al-0.7Fe alloy lamellar orientation in this embodiment is basically parallel to the direction of the magnetic field, indicating that the preparation method in this embodiment can effectively realize the preparation of unidirectional lamellar structure of titanium-aluminum alloy. Example 2

[0053] This embodiment provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, including:

[0054] S100, the Ti-43.5Al-4Nb-1Mo-0.1B alloy prepared by powder hot isostatic pressing was cut into samples with a size of Φ4×100mm using wire cutting; the sample was placed on the pull rod, and the pull rod was raised to evacuate to a vacuum degree of 1×10 - 2 Pa;

[0055] S200, set the heat treatment temperature of the device to 1300℃ and the magnetic field strength to 10T. The temperature is increased from room temperature according to a fixed heating program, and the excitation program is started at the same time. When the temperature and magnetic field strength reach the set values, the temperature is held for 30 minutes. Then the pulling is performed at a pulling speed of 10μm / s and a pulling distance of 30mm. After the pulling is completed, wait for the sample surface to cool to 100℃ and then take out the sample.

[0056] S300, polishing the cross section of the sample parallel to the magnetic field direction: first polish with SiC sandpaper to 2000#, then electropolish with an electrolyte of 60% methanol + 35% n-butanol + 5% perchloric acid, voltage 30V, time 15s, electrolyte temperature less than or equal to 10℃, after polishing, place in an ultrasonic bath, clean with alcohol and air dry, and characterize its microstructure with an optical microscope.

[0057] After obtaining the unidirectional lamellar structure of the titanium-aluminum alloy in this embodiment, its microstructure was characterized using an optical microscope. The characterization results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the Ti-43.5Al-4Nb-1Mo-0.1B alloy lamellar orientation in this embodiment is basically parallel to the direction of the magnetic field, indicating that the preparation method in this embodiment can effectively realize the preparation of unidirectional lamellar structure of titanium-aluminum alloy. Example 3

[0058] This embodiment provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, including:

[0059] S100, using wire cutting, cut the cast Ti-43Al-0.7Fe alloy into samples with dimensions of Φ4×100mm. Place the sample on the pull rod, and raise the pull rod to evacuate to a vacuum level of 5×10⁻⁶. -2 Pa;

[0060] S200, set the heat treatment temperature of the device to 1350℃ and the magnetic field strength to 10T. The temperature is increased from room temperature according to a fixed heating program, and the excitation program is started at the same time. When the temperature and magnetic field strength reach the set values, the temperature is held for 30 minutes. Then the sample is pulled out at a pulling speed of 5μm / s and a pulling distance of 20mm. After the pulling is completed, the sample is taken out after the sample surface temperature drops to 100℃.

[0061] S300, polishing the cross section of the sample parallel to the magnetic field direction: first polish with SiC sandpaper to 2000#, then electropolish with an electrolyte of 60% methanol + 35% n-butanol + 5% perchloric acid, voltage 35V, time 25s, electrolyte temperature less than or equal to 10℃. After polishing, place it in an ultrasonic bath, clean it with alcohol and air dry it. Characterize its microstructure with an optical microscope.

[0062] After obtaining the unidirectional lamellar structure of the titanium-aluminum alloy in this embodiment, its microstructure was characterized using an optical microscope. The characterization results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the Ti-43Al-0.7Fe alloy sheets in this embodiment are oriented basically parallel to the direction of the magnetic field. For example... Figure 4 As shown, electron backscatter diffraction (EBSD) results also reveal its α phase. <0001> The crystal orientation is perpendicular to the magnetic field direction, indicating that the preparation method of this embodiment can effectively realize the preparation of unidirectional lamellar structures of titanium-aluminum alloys. Example 4

[0063] This embodiment provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, including:

[0064] S100, the extruded Ti-43.25Al-3.91Nb-0.98Mo-0.1B alloy was cut into samples with dimensions of Φ4×100mm using wire cutting. The sample was placed on the pull rod, and the pull rod was raised to evacuate the vacuum to a vacuum degree of 9.5×10⁻⁶. -3 Pa;

[0065] S200, set the heat treatment temperature of the device to 1300℃ and the magnetic field strength to 10T. The temperature is increased from room temperature using a fixed heating program, and the excitation program is started at the same time. When the temperature and magnetic field strength reach the set values, the temperature is held for 60 minutes. Then, the sample is pulled out at a pulling speed of 10μm / s and a pulling distance of 30mm. After the pulling is completed, the sample is taken out after the sample surface temperature drops to 100℃.

[0066] S300, polishing the cross section of the sample parallel to the magnetic field direction: first polish with SiC sandpaper to 2000#, then electropolish with an electrolyte of 60% methanol + 35% n-butanol + 5% perchloric acid, voltage 30V, time 15s, electrolyte temperature less than or equal to 10℃, after polishing, place in an ultrasonic bath, wash with alcohol and air dry, and characterize its microstructure with an optical microscope.

[0067] After obtaining the unidirectional lamellar structure of the titanium-aluminum alloy in this embodiment, its microstructure was characterized using an optical microscope. The characterization results are as follows: Figure 5 As shown, from Figure 5 It can be seen that the Ti-43.25Al-3.91Nb-0.98Mo-0.1B alloy lamellar orientation in this embodiment is basically parallel to the direction of the magnetic field, indicating that the preparation method in this embodiment can effectively realize the preparation of unidirectional lamellar structure of titanium-aluminum alloy.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, including:

[0070] S100, the cast Ti-43Al-0.7Fe alloy was cut into samples with dimensions of Φ4×100mm using wire cutting; the sample was placed on the pull rod, and the pull rod was raised to evacuate the vacuum to a vacuum degree of 1×10⁻⁶. -2 Pa;

[0071] S200, set the heat treatment temperature of the device to 1350℃, raise the temperature from room temperature with a fixed heating program, when the temperature reaches the set value, pull at a rate of 5μm / s, pull distance of 20mm, after the pull is completed, wait for the sample surface temperature to drop to 100℃, and take out the sample.

[0072] S300, polish the cross section of the sample parallel to the magnetic field direction: first polish with SiC sandpaper to 2000#, then electropolish with 60% methanol + 35% n-butanol + 5% perchloric acid, voltage 35V, time 25s, electrolyte temperature less than or equal to 10℃, after polishing, put it in ultrasonic bath, clean it with alcohol and let it dry.

[0073] After obtaining the comparative titanium-aluminum alloy lamellar structure, its microstructure was characterized using an optical microscope. The characterization results are as follows: Figure 6 As shown, from Figure 6 It can be seen that the Ti-43Al-0.7Fe alloy lamellar orientation in this comparative example has a large angle with the direction of the magnetic field, indicating that the introduction of a strong magnetic field in the preparation method of this embodiment can effectively realize the preparation of unidirectional lamellar structure of titanium-aluminum alloy.

[0074] It should be noted that the schematic diagram of the equipment manufacturing process used in the embodiments of the present invention is as follows: Figure 7 As shown, the device is equipped with a gallium-indium-tin (Ga-In-Sn) alloy pool. In the above embodiment, during the pulling process of the titanium-aluminum alloy, the magnetic field direction is parallel and opposite to the pulling direction, and a relatively downward heat flow is maintained. This facilitates the growth of preferentially oriented α grains against the direction of heat flow. After cooling, the obtained lamellar structure orientation is nearly parallel to the magnetic field direction. In the two-step process of heat preservation and directional pulling of the titanium-aluminum alloy, the lamellar structure orientation obtained during the subsequent cooling process is parallel to the magnetic field direction, with an angular deviation of less than 10°, thus preparing a high-quality unidirectional lamellar structure of titanium-aluminum alloy. Furthermore, controlling the pulling rate is crucial during the directional pulling process. A slower pulling rate results in a better preferential alignment of the prepared lamellar structure orientation. This invention prepares a high-quality unidirectional lamellar structure of titanium-aluminum alloy under strong magnetic field conditions through two steps: heat preservation and directional pulling.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a unidirectional lamellar structure of a titanium-aluminum alloy, characterized in that, Under strong magnetic field conditions, by holding the titanium-aluminum alloy at temperatures above its α-phase transformation temperature, an additional magnetic driving force is applied using a strong magnetic field to induce the α-phase... <0001> Grains oriented perpendicular to the magnetic field direction are preferentially grown, then pulled at a certain rate. Due to the relatively downward heat flow maintained during the pulling process, the preferentially grown α grains grow against the direction of the heat flow. After cooling to room temperature, the resulting lamellar structure is oriented nearly parallel to the magnetic field direction; the strength of the magnetic field is equal to 5T; the preparation method includes: Obtain titanium-aluminum alloy billets, including cast titanium-aluminum alloys, powder hot isostatic pressing titanium-aluminum alloys, and wrought titanium-aluminum alloys; The titanium-aluminum alloy blank is machined into a cylinder with a diameter of 4-8mm, and the wire cutting marks on the sample are ground off. The titanium-aluminum alloy is installed on the pull rod of the equipment and subjected to heat treatment in a strong magnetic field and vacuum environment for 20-90 minutes; wherein the heat treatment temperature is higher than the α-phase transformation temperature of the titanium-aluminum alloy. After the heat preservation treatment is completed, directional pulling is performed. During the pulling process, the direction of the magnetic field is parallel and opposite to the pulling direction. During the directional pulling process, the heat flow is kept relatively downward. After the pulling is completed, the sample surface temperature drops below 100°C, the sample is taken out, and after cooling, a unidirectional lamellar structure of titanium-aluminum alloy is obtained. The direction of the magnetic field is parallel and opposite to the pulling direction.

2. The method for preparing a unidirectional lamellar structure of titanium-aluminum alloy according to claim 1, characterized in that, The preparation method includes two steps: heat preservation under a specified magnetic field strength and temperature, and subsequent directional pulling.

3. The method for preparing a unidirectional lamellar structure of titanium-aluminum alloy according to claim 2, characterized in that, The directional pulling rate is less than or equal to 20 μm / s.

4. The method for preparing a unidirectional lamellar structure of titanium-aluminum alloy according to claim 3, characterized in that, After the drawing process is completed, a unidirectional α2 / γ lamellar structure is formed during the cooling process.

5. The method for preparing a unidirectional lamellar structure of titanium-aluminum alloy according to claim 4, characterized in that, After the pulling process is completed, wait for the sample surface temperature to drop below 100°C, including: After the titanium-aluminum alloy is directionally pulled, and the surface temperature of the sample is reduced to below 100°C, a unidirectional lamellar structure of the titanium-aluminum alloy is obtained.

6. A unidirectional lamellar structure of a titanium-aluminum alloy, characterized in that, The titanium-aluminum alloy unidirectional lamellar structure was prepared using any one of claims 1 to 5.

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