A method for preparing fine TiAl alloy wire

Abstract

The present invention provides a method for preparing fine TiAl alloy wire, which relates to the technical field of TiAl alloy preparation. The preparation method includes the following steps: selecting and processing raw materials for wires, twisting raw materials for wires, continuous warm drawing of primary TiAl composite strands, twisting primary TiAl composite wires, continuous warm drawing of secondary TiAl composite strands, multiple warm drawing of TiAl composite wires, continuous extrusion of TiAl wires, and diffusion homogenization of TiAl alloy wires. The present invention can directly prepare TiAl alloy wires with uniform composition distribution at a relatively low temperature through multiple twistings, multiple continuous hot drawing, and final diffusion homogenization annealing, effectively avoiding a high-temperature melting process. The composition and diameter of the TiAl alloy wires can be designed according to the requirements of the target TiAl alloy wires in the preparation and extrusion processes of the TiAl composite wires. The method has high flexibility, simple operation, wide applicability, and low cost, and is very suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of TiAl alloy preparation, in particular to a method for preparing fine TiAl alloy wire. Background Art

[0002] TiAl alloy is an intermetallic compound formed by Ti and Al in a nearly equal atomic ratio. It has the advantages of low density, high specific strength, and good corrosion resistance, especially good oxidation resistance and excellent mechanical properties at high temperatures. Therefore, TiAl alloy has become the currently recognized best new lightweight and high-temperature resistant structural material to replace nickel-based high-temperature alloys. In recent years, with the continuous development of large aircraft, aero-engines, and new-generation launch vehicles, the structure of aerospace TiAl alloy parts has tended to be integrated and complex, and the traditional casting, forging combined with machining production model can no longer meet the high-efficiency, low-cost complex structure manufacturing needs. At present, additive manufacturing technology is increasingly used in the manufacture of TiAl alloys in aerospace.

[0003] Because additive manufacturing technology is based on a bottom-up, layer-by-layer accumulation principle, it excels at complex molding. Depending on the feeding method, it can be categorized into three types: powder laying, powder feeding, and wire feeding. However, powder additive manufacturing requires high-quality raw materials, resulting in slow deposition rates during the preparation process. Furthermore, due to the limitations of existing powder production technology, powders are expensive. In contrast, fused filament additive manufacturing, which uses wire as a raw material, offers fast deposition rates, low production costs, and greater molding freedom.

[0004] Therefore, additively manufactured TiAl alloys have shown great application prospects in the aerospace field. Among them, fused filament additively manufactured TiAl alloys can break through shape constraints while having the advantages of high forming efficiency and low production cost, and are expected to further enhance the engineering application of complex structure TiAl alloys.

[0005] However, due to the poor room-temperature plasticity of TiAl alloys, drawing them into shape is difficult. Existing TiAl alloy fused filament additive manufacturing (FFAM) often relies on a dual-wire feeding method: "Ti wire + Al wire." This method, however, is complex and requires high equipment costs. Even single-wire feeding methods, which use TiAl composite wire as the raw material, present challenges such as complex wire preparation and uneven composition distribution. Therefore, a method for preparing TiAl alloy wire is urgently needed to meet the demands of high-quality FFAM for TiAl alloys.

[0006] For example, Chinese patent CN106636706A discloses a TiAl alloy wire for 3D printing and a method for preparing the same. The alloy wire is prepared by smelting the ingredients, heating and melting, spraying, and drawing. Obviously, it is difficult to achieve uniform distribution of the composition of the alloy wire prepared by drawing, and the alloy wire cannot be mass-produced and is only suitable for laboratory research. The rotation speed of the copper alloy roller is very high, making it difficult to control the quality of the alloy wire.

[0007] Chinese patent CN113523643A discloses Ti / Al composite wire for additive manufacturing of TiAl alloy and its preparation method. The Ti / Al composite wire for TiAl alloy is made of an inner core material and an outer layer material coated on the inner core material. The outer layer material and the inner core material are then processed and assembled, and then swaged and drawn to obtain the Ti / Al composite wire. The Ti / Al composite wire prepared by this method has an uneven distribution of components and a complex preparation method. It may have technical defects such as cracks, irregular streamline distribution, banded structure, and eccentricity.

[0008] Chinese patent CN112139649A discloses a method for in-situ additive preparation of titanium-aluminum intermetallic compounds based on electron beam double-filament fuses. The method is prepared through preliminary preparation - in-situ additive preparation - additive component cooling. The fuse raw materials are aluminum wire and titanium wire, which need to be fed simultaneously and into the same molten pool for deposition. The operation is difficult, costly, and inefficient, and the distribution of the deposited components is uneven. Summary of the Invention

[0009] In order to solve the problems in the prior art of the preparation of fused wires, such as the uneven distribution of the composition of the TiAl alloy raw wire, component segregation, poor room temperature plasticity, which lead to the inability to draw the wire, as well as the complex structure of the device used in the preparation process, high difficulty in operation, high cost, low efficiency, etc., which makes it difficult to ensure the performance of TiAl alloy parts and the uniformity of the composition of each part during the fused wire additive manufacturing deposition process, further causing technical problems such as poor stability of TiAl alloy products; therefore, the embodiment of the present invention provides a method for preparing a fine TiAl alloy wire with low cost, simple preparation method, uniform composition distribution, high mechanical properties, low temperature toughness and fatigue strength. The technical solution is as follows:

[0010] A method for preparing a fine TiAl alloy wire comprises the following steps:

[0011] S1. Selection and processing of wire raw materials: According to the composition and mass ratio of the target TiAl alloy wire, a plurality of Ti wires and a plurality of Al wires are selected as wire raw materials; and the wire raw materials are ultrasonically cleaned using commercially available cleaning agents to obtain wire raw materials with clean surfaces;

[0012] S2. Twisting of wire raw materials: Twisting the wire raw materials in S1 tightly together through a stranding machine to obtain a primary TiAl composite strand with a multi-helical structure;

[0013] S3, continuous warm drawing of primary TiAl composite strand: the primary TiAl composite strand prepared in S2 is subjected to continuous multi-pass hot drawing, and the entire process is automatically transmitted to obtain a primary TiAl composite wire;

[0014] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine to obtain secondary TiAl composite twisted wires with a multi-helical structure;

[0015] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 are subjected to continuous multi-pass hot drawing, with the entire process being automatically conveyed to obtain secondary TiAl composite wires;

[0016] S6. Multiple warm drawing of the TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of the TiAl composite wire, repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, tightly twist the cut TiAl composite wires together through a stranding machine, and then perform the next warm drawing until the target number of passes is completed to obtain the TiAl composite wire;

[0017] S7, continuous extrusion of TiAl wire: the TiAl composite wire prepared in S6 is continuously drawn and extruded through a continuous wire drawing machine, and the entire process is automatically transmitted until the target pass is stopped to obtain a TiAl alloy wire;

[0018] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 is subjected to diffusion homogenization treatment in a vacuum furnace, and fine TiAl alloy wire with uniform composition is obtained after cooling in the furnace.

[0019] Optionally, the wire material in S1 can use existing brand wire, or be customized to adjust the composition; the wire material diameter is 1-5mm; the frequency of ultrasonic cleaning is 20-60kHz, and the power is 240-720W.

[0020] Optionally, the speed of the stranding machine in S2 and S4 is greater than 500 rpm, and the length of the stranded wire after stranding is 70-90% of the wire raw material; the multi-helix structure is a double helix structure or a structure with more than double helix.

[0021] Optionally, the continuous multi-pass hot drawing in S3 and S5 is specifically as follows: first heating to 250-500°C and preheating the drawing die to 250-500°C, and then performing continuous multi-pass drawing, with a drawing rate of 5-30m / min, a deformation amount of each drawing of 10-20%, and a total deformation amount of multi-pass drawing of 20-90%; the tensile strength of the TiAl composite wire is 100-700MPa, the yield strength is 50-600MPa, and the elongation is 6-30%.

[0022] Optionally, S4 is divided into two or more equal parts.

[0023] Optionally, the secondary TiAl composite wire in S5 has a tensile strength of 100-700 MPa, a yield strength of 50-600 MPa, and an elongation of 6-30%.

[0024] Optionally, the number of continuous warm drawing passes in S6 is 2-10 times, the tensile strength of the TiAl composite wire is 100-700 MPa, the yield strength is 50-600 MPa, and the elongation is 6-30%.

[0025] Optionally, the extrusion rate of the continuous drawing extrusion in S7 is 1-20 m / min, the wire drawing machine temperature is 600-1000°C, the extrusion die diameter is 0.8-5 mm and the diameter decreases gradually by 0.2-1 mm, the extrusion target pass matches the TiAl pre-alloyed wire diameter, the extrusion die diameter and the diameter reduction per pass, the tensile strength of the TiAl alloy wire is 300-650 MPa, the yield strength is 200-550 MPa, and the elongation is 3-10%.

[0026] Optionally, the temperature of the diffusion homogenization treatment in S8 is 600-900°C, the holding time is 60-120 minutes, and the vacuum degree is 10 -1 ~10 -3 Pa, the tensile strength of the fine TiAl alloy wire with uniform composition is 400-750MPa, the yield strength is 300-650MPa, and the elongation is 3-10.

[0027] Optionally, the preparation method described in S1-S8 is not only applicable to TiAl alloys, but also to Ti-Al-Nb alloys, Ti-Al-V alloys, Ti-Cu alloys, Ti-Ni alloys, Ti-Fe alloys and Ti-Mo alloys.

[0028] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0029] The present invention proposes a method for preparing fine TiAl alloy wire, which can overcome the technical bottleneck of producing TiAl alloy wire by wire drawing due to the poor room temperature plasticity of TiAl alloy, thereby addressing the limited application of TiAl alloy wire. Traditional single-filament additive manufacturing technology using TiAl composite wire as raw material suffers from complex wire preparation and uneven finished product composition. The fine TiAl alloy wire obtained by the present invention has a uniform composition and structure, a dense structure, a smooth surface, and is free of defects such as oxidation, cracking, and porosity. The performance of all parts of the fused filament additive manufacturing products using this raw material is stable and consistent, providing high-quality raw material for expanding the application of TiAl alloy.

[0030] The present invention is not limited to the preparation of TiAl alloy wires, but is also applicable to the preparation of titanium-containing alloy wires such as Ti-Al-Nb, Ti-Al-V, Ti-Cu, Ti-Ni, Ti-Fe and Ti-Mo. There are no special restrictions on the raw material brand and composition, and the range of selectable raw materials is wide. Additive manufacturing can prepare a large number of titanium-containing alloys with complex shapes and different compositions, which is conducive to large-scale industrial production and commercial promotion and application.

[0031] The present invention utilizes the good room temperature plasticity of a single metal wire, adopts the alloy single metal wire to be compounded, and forms a tight spiral structure with two or more of the aforementioned single metal wires through a twisting method. Combined with a multi-pass continuous warm drawing process, the pre-alloying of the alloy single metal to be compounded can be achieved at a relatively low temperature. The operation is convenient, the cost is low, and it can be applied to the additive manufacturing of complex-shaped alloys with different performance requirements.

[0032] Compared with the cold drawing method, the continuous warm drawing method adopted in the present invention can improve the plastic deformation ability of the wire during the drawing process, reduce the deformation resistance, ensure that no cracking or wire breakage occurs during the deformation process, and can effectively reduce the number of drawing passes and reduce the internal stress of the prepared wire, thereby significantly improving the preparation efficiency of the wire.

[0033] The present invention can completely alloy the pre-alloyed TiAl composite wire by continuously drawing and extruding it at a relatively low temperature with a gradually decreasing die diameter. This avoids the high-temperature melting process, solves the technical bottleneck of the difficulty in preparing alloy wire due to the brittleness of TiAl alloy at room temperature, and effectively reduces the volatilization of low-melting-point Al elements during the preparation of TiAl alloy wire.

[0034] The diffusion homogenization annealing treatment adopted in the present invention can further diffuse the heterogeneous elements in the TiAl alloy wire, ensure that the composition distribution of the obtained TiAl alloy wire is completely uniform, increase the uniformity of the composition distribution of the wire after melting in the additive manufacturing process, and improve the yield of the printed product.

[0035] The automatic conveying device adopted by the present invention can greatly improve the production efficiency of TiAl alloy wire, effectively reduce its production cost, eliminate manual interference in alloy wire preparation, and further improve the production quality of TiAl alloy wire.

[0036] The present invention can make adaptive adjustments in the pass selection during the preparation and extrusion of TiAl composite wires according to the component ratio and diameter of the target TiAl alloy wire, ensuring that the components of TiAl alloy wires with different compositions are evenly distributed and the diameters meet the requirements, and the wires all have high quality and high performance.

[0037] The tensile strength, yield strength and yield strength ratio of the fine TiAl alloy wire prepared by the present invention gradually increase as the process progresses, and the tensile strength can reach about 700 MPa, and the maximum can approach 720 MPa; similarly, the yield strength ratio is above 0.9, and the maximum can approach 0.985.

[0038] In summary, compared with other traditional methods, the method of the present invention can directly prepare TiAl alloy wires with uniform composition distribution at a lower temperature through multiple twisting, multiple continuous hot drawing and final diffusion homogenization annealing, effectively avoiding the high-temperature melting process. The composition and diameter of the TiAl alloy wire can be designed according to the requirements of the target TiAl alloy wire in the preparation and extrusion process of the TiAl composite wire. It has high flexibility, simple operation, wide applicability and low cost, and is very suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 This is a process flow chart of a method for preparing a fine TiAl alloy wire of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0042] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0043] In the embodiments of the present invention, "image" and "picture" may sometimes be used interchangeably. It should be noted that, when the distinction between them is not emphasized, the meanings they convey are the same. "of," "corresponding," and "corresponding" may sometimes be used interchangeably. It should be noted that, when the distinction between them is not emphasized, the meanings they convey are the same.

[0044] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0045] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0046] A method for preparing a fine TiAl alloy wire, such as Figure 1 As shown, the preparation method of the fine TiAl alloy wire comprises the following steps:

[0047] S1. Selection and processing of wire raw materials: According to the composition and mass ratio of the target TiAl alloy wire, a plurality of Ti wires and a plurality of Al wires are selected as wire raw materials; and the wire raw materials are ultrasonically cleaned using commercially available cleaning agents to obtain wire raw materials with clean surfaces;

[0048] S2. Twisting of wire raw materials: Twisting the wire raw materials in S1 tightly together through a stranding machine to obtain a primary TiAl composite strand with a multi-helical structure;

[0049] S3, continuous warm drawing of primary TiAl composite strand: the primary TiAl composite strand prepared in S2 is subjected to continuous multi-pass hot drawing, and the entire process is automatically transmitted to obtain a primary TiAl composite wire;

[0050] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine to obtain secondary TiAl composite twisted wires with a multi-helical structure;

[0051] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 are subjected to continuous multi-pass hot drawing, with the entire process being automatically conveyed to obtain secondary TiAl composite wires;

[0052] S6. Multiple warm drawing of the TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of the TiAl composite wire, repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, tightly twist the cut TiAl composite wires together through a stranding machine, and then perform the next warm drawing until the target number of passes is completed to obtain the TiAl composite wire;

[0053] S7, continuous extrusion of TiAl wire: the TiAl composite wire prepared in S6 is continuously drawn and extruded through a continuous wire drawing machine, and the entire process is automatically transmitted until the target pass is stopped to obtain a TiAl alloy wire;

[0054] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 is subjected to diffusion homogenization treatment in a vacuum furnace, and fine TiAl alloy wire with uniform composition is obtained after cooling in the furnace.

[0055] In particular, the wire raw material in S1 uses existing brands of wire, or customized design and composition adjustment; the wire raw material diameter is 1-5mm; the frequency of ultrasonic cleaning is 20-60kHz, and the power is 240-720W.

[0056] In particular, in S2 and S4, the speed of the stranding machine is greater than 500 rpm, the length of the stranded wire after stranding is 70-90% of the wire raw material; and the multi-helix structure is a double helix structure or a structure with more than double helix.

[0057] In particular, the continuous multi-pass hot drawing in S3 and S5 is specifically as follows: first heating to 250-500°C and preheating the drawing die to 250-500°C, then performing continuous multi-pass drawing, with a drawing rate of 5-30m / min, a deformation of 10-20% per drawing, and a total deformation of 20-90% for multi-pass drawing; the tensile strength of the TiAl composite wire is 100-700MPa, the yield strength is 50-600MPa, and the elongation is 6-30%.

[0058] In particular, S4 is divided into two or more equal parts.

[0059] In particular, the tensile strength of the secondary TiAl composite wire in S5 is 100-700 MPa, the yield strength is 50-600 MPa, and the elongation is 6-30%.

[0060] In particular, the number of continuous warm drawing passes in S6 is 2-10 times, the tensile strength of the TiAl composite wire is 100-700 MPa, the yield strength is 50-600 MPa, and the elongation is 6-30%.

[0061] In particular, the extrusion rate of the continuous drawing extrusion in S7 is 1-20 m / min, the wire drawing machine temperature is 600-1000°C, the extrusion die diameter is 0.8-5 mm and the diameter decreases gradually by 0.2-1 mm. The target extrusion passes match the TiAl pre-alloyed wire diameter, the extrusion die diameter, and the diameter reduction per pass. The tensile strength of the TiAl alloy wire is 300-650 MPa, the yield strength is 200-550 MPa, and the elongation is 3-10%.

[0062] In particular, the temperature of the diffusion homogenization treatment in S8 is 600-900℃, the holding time is 60-120min, and the vacuum degree is 10 -1 ~10 -3 Pa, the tensile strength of the fine TiAl alloy wire with uniform composition is 400-750MPa, the yield strength is 300-650MPa, and the elongation is 3-10%.

[0063] In particular, the preparation method described in S1-S8 is not only applicable to TiAl alloys, but also to Ti-Al-Nb alloys, Ti-Al-V alloys, Ti-Cu alloys, Ti-Ni alloys, Ti-Fe alloys and Ti-Mo alloys.

[0064] Example 1

[0065] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 52% and Al 48% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0066] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, five Ti wires and five Al wires, each with a diameter of 2 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 40 kHz and a power of 360 W to obtain surface-cleaned wire raw materials.

[0067] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 800 rpm. The length of the twisted wire is 80% of the length of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a double helical structure.

[0068] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 400°C and the drawing die was preheated to 380°C. Continuous multi-pass drawing was then performed at a drawing rate of 9 m / min. The deformation per drawing was 12%, and the total deformation over the multi-pass drawing was 60%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 310 MPa, a yield strength of 232 MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 3.10 GPa·%;

[0069] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into two equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 1000 rpm. The length of the twisted wire is 75% of half of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite twisted wire with a double helical structure;

[0070] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 450°C and the drawing die was preheated to 400°C. The strands were then drawn continuously at a rate of 15 m / min. Each drawing had a deformation of 15%, and the total deformation for the multi-pass drawing was 75%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 315 MPa, a yield strength of 252 MPa, a yield strength ratio of 0.800, an elongation of 7%, and a strength-ductility product of 2.21 GPa·%;

[0071] S6. Multiple warm drawing of TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of the TiAl composite wire. The continuous warm drawing passes are 2 times, and there is no need to repeat S4-S5.

[0072] S7. Continuous extrusion of TiAl wire: The secondary TiAl composite wire prepared in S5 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 15 m / min, a wire drawing machine temperature of 850°C, an extrusion die diameter of 3 mm, and a diameter that decreased by 0.5 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was reached, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 512 MPa, a yield strength of 460 MPa, a yield strength ratio of 0.898, an elongation of 6%, and a strength-ductility product of 3.07 GPa·%;

[0073] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 800°C, the holding time was 75 min, and the vacuum degree was 10 -1 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 668 MPa, a yield strength of 621 MPa, a yield strength ratio of 0.930, an elongation of 5%, and a strength-ductility product of 3.34 GPa·%.

[0074] The fine TiAl alloy wire obtained in this embodiment has a diameter of 1 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0075] Example 2

[0076] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 53% and Al 47% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0077] S1. Selection and processing of wire raw materials: Based on the target TiAl alloy wire composition and mass ratio, six Ti wires and four Al wires, each with a diameter of 3 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 600 kHz and a power of 720 W to obtain surface-cleaned wire raw materials.

[0078] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 500 rpm. The length of the stranded wire after twisting is 85% of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a multi-helical structure;

[0079] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 300°C and the drawing die was preheated to 270°C. Continuous multi-pass drawing was then performed at a drawing rate of 6 m / min. The deformation per drawing was 10%, and the total deformation over the multi-pass drawing was 50%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 412 MPa, a yield strength of 288 MPa, a yield strength ratio of 0.699, an elongation of 14.1%, and a strength-ductility product of 5.81 GPa·%;

[0080] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 800 rpm. The length of the twisted wire is 80% of one-third of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite strand with a multi-helical structure;

[0081] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 370°C and the drawing die was preheated to 350°C. The strands were then drawn continuously at a rate of 8 m / min. Each drawing had a deformation of 13%, and the total deformation for the multi-pass drawing was 65%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 437 MPa, a yield strength of 327 MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 4.37 GPa·%;

[0082] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined based on the uniformity of the TiAl composite wire. The continuous warm drawing passes are four times, and S4-S5 are repeated. That is, the TiAl composite wire from the previous warm drawing is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is carried out until the target number of passes is completed. The entire process is automatically transmitted to obtain the TiAl composite wire. The tensile strength of the TiAl composite wire is 447 MPa, the yield strength is 366 MPa, the yield strength ratio is 0.819, the elongation is 7%, and the strength-ductility product is 3.13 GPa·%;

[0083] S7. Continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 18 m / min, a wire drawing machine temperature of 900°C, an extrusion die diameter of 4 mm, and a diameter that decreased by 0.2 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was stopped, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 580 MPa, a yield strength of 527 MPa, a yield strength ratio of 0.909, an elongation of 7%, and a strength-ductility product of 4.06 GPa·%;

[0084] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 750°C, the holding time was 100 min, and the vacuum degree was 10 -2 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 693 MPa, a yield strength of 648 MPa, a yield strength ratio of 0.935, an elongation of 6.8%, and a strength-ductility product of 4.71 GPa·%.

[0085] The fine TiAl alloy wire obtained in this embodiment has a diameter of 3 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0086] Comparative Example 1

[0087] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 52% and Al 48% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0088] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, five Ti wires and five Al wires, each with a diameter of 2 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 40 kHz and a power of 360 W to obtain surface-cleaned wire raw materials.

[0089] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 800 rpm. The length of the twisted wire is 80% of the length of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a double helical structure.

[0090] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 400°C and the drawing die was preheated to 380°C. Continuous multi-pass drawing was then performed at a drawing rate of 9 m / min. The deformation per drawing was 12%, and the total deformation over the multi-pass drawing was 60%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 310 MPa, a yield strength of 232 MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 3.10 GPa·%;

[0091] S4. Continuous extrusion of TiAl wire: The secondary TiAl composite wire prepared in S5 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 15 m / min, a wire drawing machine temperature of 850°C, an extrusion die diameter of 3 mm, and a diameter that decreased by 0.5 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was stopped, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 430 MPa, a yield strength of 365 MPa, a yield strength ratio of 0.849, an elongation of 6%, and a strength-ductility product of 2.58 GPa·%;

[0092] S5. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 800°C, the holding time was 75 min, and the vacuum degree was 10 -1 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 550 MPa, a yield strength of 496 MPa, a yield strength ratio of 0.902, an elongation of 2%, and a strength-ductility product of 1.10 GPa·%.

[0093] The diameter of the fine TiAl alloy wire obtained in this comparative example is 1 mm. Since the continuous warm drawing pass is only one, the wires of different components are mixed unevenly, and the prepared fine TiAl alloy wire has the problem of uneven composition and microstructure.

[0094] Comparative Example 2

[0095] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 53% and Al 47% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0096] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, six Ti wires and four Al wires, each with a diameter of 3 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 60 kHz and a power of 720 W to obtain surface-cleaned wire raw materials.

[0097] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 500 rpm. The length of the stranded wire after twisting is 85% of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a multi-helical structure;

[0098] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 300°C and the drawing die was preheated to 270°C. Continuous multi-pass drawing was then performed at a drawing rate of 6 m / min. The deformation per drawing was 10%, and the total deformation over the multi-pass drawing was 50%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 412 MPa, a yield strength of 288 MPa, a yield strength ratio of 0.699, an elongation of 14.1%, and a strength-ductility product of 5.81 GPa·%;

[0099] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 800 rpm. The length of the twisted wire is 80% of one-third of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite strand with a multi-helical structure;

[0100] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 370°C and the drawing die was preheated to 350°C. The strands were then drawn continuously at a rate of 8 m / min. Each drawing had a deformation of 13%, and the total deformation for the multi-pass drawing was 65%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 437 MPa, a yield strength of 327 MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 4.37 GPa·%;

[0101] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined based on the uniformity of the TiAl composite wire. The continuous warm drawing passes are four times, and S4-S5 are repeated. That is, the TiAl composite wire from the previous warm drawing is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is carried out until the target number of passes is completed. The entire process is automatically transmitted to obtain the TiAl composite wire. The tensile strength of the TiAl composite wire is 447 MPa, the yield strength is 366 MPa, the yield strength ratio is 0.819, the elongation is 7%, and the strength-ductility product is 3.13 GPa·%;

[0102] S7. Continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 18 m / min, a wire drawing machine temperature of 1200°C, an extrusion die diameter of 4 mm, and a diameter that decreased by 0.2 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was reached, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 620 MPa, a yield strength of 576 MPa, a yield strength ratio of 0.929, an elongation of 2%, and a strength-ductility product of 1.24 GPa·%;

[0103] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 1100°C, the holding time was 100 min, and the vacuum degree was 10 -2 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 705 MPa, a yield strength of 691 MPa, a yield strength ratio of 0.980, an elongation of 0.5%, and a strength-ductility product of 0.35 GPa·%.

[0104] The diameter of the fine TiAl alloy wire obtained in this comparative example is 3 mm. Due to the high temperature of continuous extrusion and diffusion homogenization treatment, problems such as wire breakage, oxidation, and cracking occurred during the extrusion process.

[0105] In summary, by comparing the examples with the comparative examples, it can be found that the selection of continuous warm drawing passes and the setting of continuous extrusion parameters will directly determine the uniformity of the final TiAl alloy wire. In addition, due to the room temperature brittleness of TiAl alloy, inappropriate temperature parameters will lead to problems such as wire breakage, cracking, and oxidation during the wire preparation process. Therefore, in actual operation, it is necessary to reasonably set each parameter based on the target TiAl alloy wire properties to obtain high-quality TiAl alloy wire with uniform composition and microstructure, dense structure, smooth surface, and no defects such as oxidation, cracking, and porosity.

[0106] Example 3

[0107] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 54% and Al 46% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0108] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, three Ti wires and three Al wires, each with a diameter of 4 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 20 kHz and a power of 240 W to obtain surface-cleaned wire raw materials.

[0109] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 1000 rpm. The length of the stranded wire after twisting is 75% of the raw materials of the wire, thereby obtaining a primary TiAl composite stranded wire with a multi-helical structure;

[0110] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 480°C and the drawing die was preheated to 450°C. Continuous multi-pass drawing was then performed at a drawing rate of 20 m / min. The deformation per drawing was 15%, and the total deformation over the multi-pass drawing was 60%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 452 MPa, a yield strength of 325 MPa, a yield strength ratio of 0.719, an elongation of 12.9%, and a strength-ductility product of 8.09 GPa·%;

[0111] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into four equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 1500 rpm. The length of the twisted wire is 70% of one-quarter of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite stranded wire with a multi-helical structure;

[0112] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 480°C and the drawing die was preheated to 450°C. The strands were then drawn continuously at a rate of 18 m / min. Each drawing had a deformation of 14%, and the total deformation for the multi-pass drawing was 70%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 483 MPa, a yield strength of 376 MPa, a yield strength ratio of 0.778, an elongation of 8%, and a strength-ductility product of 3.86 GPa·%;

[0113] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined based on the uniformity of the TiAl composite wire. The continuous warm drawing passes are 5 times. S4-S5 are repeated, i.e., the previous TiAl composite wire is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is performed until the target number of passes is completed to obtain the TiAl composite wire. The TiAl composite wire has a tensile strength of 525 MPa, a yield strength of 435 MPa, a yield strength ratio of 0.829, an elongation of 6.5%, and a strength-ductility product of 3.41 GPa·%;

[0114] S7. Continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 10 m / min, a wire drawing machine temperature of 770°C, an extrusion die diameter of 5 mm, and a diameter that decreased by 0.5 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was stopped, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 597 MPa, a yield strength of 525 MPa, a yield strength ratio of 0.879, an elongation of 5%, and a strength-ductility product of 2.99 GPa·%;

[0115] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 680°C, the holding time was 120 min, and the vacuum degree was 10 -3 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 711 MPa, a yield strength of 645 MPa, a yield strength ratio of 0.907, an elongation of 7%, and a strength-ductility product of 4.98 GPa·%.

[0116] The fine TiAl alloy wire obtained in this embodiment has a diameter of 2 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0117] Example 4

[0118] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 54% and Al 46% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0119] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, five Ti wires and five Al wires, each with a diameter of 2 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 60 kHz and a power of 720 W to obtain surface-cleaned wire raw materials.

[0120] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 800 rpm. The length of the twisted wire is 80% of the length of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a double helical structure.

[0121] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 400°C and the drawing die was preheated to 380°C. Continuous multi-pass drawing was then performed at a drawing rate of 9 m / min. The deformation per drawing was 12%, and the total deformation over the multi-pass drawing was 60%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 413 MPa, a yield strength of 293 MPa, a yield strength ratio of 0.709, an elongation of 13.8%, and a strength-ductility product of 5.70 GPa·%;

[0122] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into two equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 1000 rpm. The length of the twisted wire is 75% of half of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite twisted wire with a double helical structure;

[0123] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 450°C and the drawing die was preheated to 400°C. The strands were then drawn continuously at a rate of 15 m / min. Each drawing had a deformation of 15%, and the total deformation for the multi-pass drawing was 75%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 447 MPa, a yield strength of 344 MPa, a yield strength ratio of 0.770, an elongation of 9.7%, and a strength-ductility product of 4.34 GPa·%;

[0124] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined based on the uniformity of the TiAl composite wire. The continuous warm drawing passes are three times, and S4-S5 are repeated. That is, the previous TiAl composite wire is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is performed until the target number of passes is completed to obtain the TiAl composite wire. The TiAl composite wire has a tensile strength of 466 MPa, a yield strength of 370 MPa, a yield strength ratio of 0.794, an elongation of 7.3%, and a strength-ductility product of 3.40 GPa·%;

[0125] S7. Continuous extrusion of TiAl wire: The secondary TiAl composite wire prepared in S5 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 15 m / min, a wire drawing machine temperature of 850°C, an extrusion die diameter of 3 mm, and a diameter that decreased by 0.5 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was reached, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 584 MPa, a yield strength of 513 MPa, a yield strength ratio of 0.878, an elongation of 8.8%, and a strength-ductility product of 5.14 GPa·%;

[0126] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 800°C, the holding time was 75 min, and the vacuum degree was 10 -1 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 698 MPa, a yield strength of 649 MPa, a yield strength ratio of 0.930, an elongation of 7.4%, and a strength-ductility product of 5.17 GPa·%.

[0127] The fine TiAl alloy wire obtained in this embodiment has a diameter of 1 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0128] Example 5

[0129] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 53% and Al 47% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0130] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, three Ti wires and three Al wires, each with a diameter of 4 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 20 kHz and a power of 240 W to obtain surface-cleaned wire raw materials.

[0131] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 1000 rpm. The length of the stranded wire after twisting is 75% of the raw materials of the wire, thereby obtaining a primary TiAl composite stranded wire with a multi-helical structure;

[0132] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 480°C and the drawing die was preheated to 450°C. Continuous multi-pass drawing was then performed at a drawing rate of 20 m / min. The deformation per drawing was 15%, and the total deformation over the multi-pass drawing was 60%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 488 MPa, a yield strength of 356 MPa, a yield strength ratio of 0.730, an elongation of 12.5%, and a strength-ductility product of 6.10 GPa·%;

[0133] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into four equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 1500 rpm. The length of the twisted wire is 70% of one-quarter of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite stranded wire with a multi-helical structure;

[0134] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 480°C and the drawing die was preheated to 450°C. The strands were then drawn continuously at a rate of 18 m / min. Each drawing had a deformation of 14%, and the total deformation for the multi-pass drawing was 70%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 517 MPa, a yield strength of 403 MPa, a yield-to-tensile strength ratio of 0.779, an elongation of 8.1%, and a strength-to-ductility product of 4.19 GPa·%;

[0135] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined based on the uniformity of the TiAl composite wire. The continuous warm drawing passes are three times. S4-S5 are repeated, i.e., the previous TiAl composite wire is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is performed until the target number of passes is completed. The entire process is automatically transmitted to obtain the TiAl composite wire. The tensile strength of the TiAl composite wire is 542 MPa, the yield strength is 439 MPa, the yield strength ratio is 0.810, the elongation is 6.8%, and the strength-ductility product is 3.69 GPa·%;

[0136] S7. Continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 10 m / min, a wire drawing machine temperature of 770°C, an extrusion die diameter of 5 mm, and a diameter that decreased by 0.5 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was stopped, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 633 MPa, a yield strength of 548 MPa, a yield strength ratio of 0.866, an elongation of 5%, and a strength-ductility product of 3.17 GPa·%;

[0137] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 680°C, the holding time was 120 min, and the vacuum degree was 10 -3 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 670 MPa, a yield strength of 626 MPa, a yield strength ratio of 0.934, an elongation of 5%, and a strength-ductility product of 3.35 GPa·%.

[0138] The fine TiAl alloy wire obtained in this embodiment has a diameter of 2 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0139] Example 6

[0140] A method for preparing a fine TiAl alloy wire, wherein the composition of the TiAl alloy wire is as follows: Ti 52% and Al 48% by mass. The method for preparing the fine TiAl alloy wire comprises the following steps:

[0141] S1. Selection and processing of wire raw materials: Based on the mass ratio of the target TiAl alloy wire components, six Ti wires and four Al wires, each with a diameter of 3 mm, were selected as wire raw materials. The wire raw materials were ultrasonically cleaned using commercially available cleaning agents at a frequency of 60 kHz and a power of 720 W to obtain surface-cleaned wire raw materials.

[0142] S2. Twisting of the raw materials of the wire: The raw materials of the wire in S1 are tightly twisted together by a twisting machine at a speed of 500 rpm. The length of the stranded wire after twisting is 85% of the raw materials of the wire, thereby obtaining a primary TiAl composite strand with a multi-helical structure;

[0143] S3. Continuous warm drawing of a primary TiAl composite strand: The primary TiAl composite strand prepared in S2 was subjected to continuous multi-pass hot drawing. The strand was first heated to 300°C and the drawing die was preheated to 270°C. Continuous multi-pass drawing was then performed at a drawing rate of 6 m / min. The deformation of each drawing was 10%, and the total deformation of the multi-pass drawing was 50%. The entire process was automatically transmitted to obtain a primary TiAl composite wire. The primary TiAl composite wire had a tensile strength of 243 MPa, a yield strength of 158 MPa, a yield strength ratio of 0.650, an elongation of 15%, and a strength-ductility product of 3.65 GPa·%;

[0144] S4, twisting of primary TiAl composite wires: the primary TiAl composite wire prepared in S3 is divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine at a twisting machine speed of 800 rpm. The length of the twisted wire is 80% of one-third of the primary TiAl composite wire, thereby obtaining a secondary TiAl composite strand with a multi-helical structure;

[0145] S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 were subjected to continuous multi-pass hot drawing. The strands were first heated to 370°C and the drawing die was preheated to 350°C. The strands were then drawn continuously at a rate of 8 m / min. Each drawing had a deformation of 13%, and the total deformation for the multi-pass drawing was 65%. The entire process was automatically transmitted to obtain a secondary TiAl composite wire. The secondary TiAl composite wire had a tensile strength of 257 MPa, a yield strength of 182 MPa, a yield strength ratio of 0.708, an elongation of 13.4%, and a strength-ductility product of 3.44 GPa·%;

[0146] S6. Multiple warm drawing of the TiAl composite wire: The number of warm drawing passes is determined according to the uniformity of the TiAl composite wire. The continuous warm drawing passes are 5 times. S4-S5 are repeated, i.e., the TiAl composite wire from the previous step is divided into multiple equal parts along the cross section. The cut TiAl composite wires are tightly twisted together by a stranding machine, and then the next warm drawing is performed until the target number of passes is completed. The entire process is automatically transmitted to obtain the TiAl composite wire. The tensile strength of the TiAl composite wire is 320 MPa, the yield strength is 252 MPa, the yield strength ratio is 0.788, the elongation is 7.4%, and the strength-ductility product is 2.37 GPa·%;

[0147] S7. Continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 was continuously drawn and extruded through a continuous wire drawing machine at an extrusion rate of 18 m / min, a wire drawing machine temperature of 900°C, an extrusion die diameter of 4 mm, and a diameter that decreased by 0.2 mm each time. The target extrusion pass matched the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process was automatically transmitted until the target pass was stopped, thereby obtaining a TiAl alloy wire. The TiAl alloy wire had a tensile strength of 556 MPa, a yield strength of 511 MPa, a yield strength ratio of 0.919, an elongation of 7%, and a strength-ductility product of 3.89 GPa·%;

[0148] S8. Diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 was subjected to diffusion homogenization treatment in a vacuum furnace. The temperature of the diffusion homogenization treatment was 750°C, the holding time was 100 min, and the vacuum degree was 10 -2 Pa, and after cooling in the furnace, fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 662 MPa, a yield strength of 615 MPa, a yield strength ratio of 0.929, an elongation of 7.2%, and a strength-ductility product of 4.77 GPa·%.

[0149] The fine TiAl alloy wire obtained in this embodiment has a diameter of 3 mm, uniform composition and microstructure, dense structure, smooth surface, no defects such as oxidation, cracking, and porosity, and no wire breakage during the preparation process.

[0150] The present invention proposes a method for preparing fine TiAl alloy wire, which can overcome the technical bottleneck of producing TiAl alloy wire by wire drawing due to the poor room temperature plasticity of TiAl alloy, thereby addressing the limited application of TiAl alloy wire. Traditional single-filament additive manufacturing technology using TiAl composite wire as raw material suffers from complex wire preparation and uneven finished product composition. The fine TiAl alloy wire obtained by the present invention has a uniform composition and structure, a dense structure, a smooth surface, and is free of defects such as oxidation, cracking, and porosity. The performance of all parts of the fused filament additive manufacturing products using this raw material is stable and consistent, providing high-quality raw material for expanding the application of TiAl alloy.

[0151] The present invention is not limited to the preparation of TiAl alloy wires, but is also applicable to the preparation of titanium-containing alloy wires such as Ti-Al-Nb, Ti-Al-V, Ti-Cu, Ti-Ni, Ti-Fe and Ti-Mo. There are no special restrictions on the raw material brand and composition, and the range of selectable raw materials is wide. Additive manufacturing can prepare a large number of titanium-containing alloys with complex shapes and different compositions, which is conducive to large-scale industrial production and commercial promotion and application.

[0152] The present invention utilizes the good room temperature plasticity of a single metal wire, adopts the alloy single metal wire to be compounded, and forms a tight spiral structure with two or more of the aforementioned single metal wires through a twisting method. Combined with a multi-pass continuous warm drawing process, the pre-alloying of the alloy single metal to be compounded can be achieved at a relatively low temperature. The operation is convenient, the cost is low, and it can be applied to the additive manufacturing of complex-shaped alloys with different performance requirements.

[0153] Compared with the cold drawing method, the continuous warm drawing method adopted in the present invention can improve the plastic deformation ability of the wire during the drawing process, reduce the deformation resistance, ensure that no cracking or wire breakage occurs during the deformation process, and can effectively reduce the number of drawing passes and reduce the internal stress of the prepared wire, thereby significantly improving the preparation efficiency of the wire.

[0154] The present invention can completely alloy the pre-alloyed TiAl composite wire by continuously drawing and extruding it at a relatively low temperature with a gradually decreasing die diameter. This avoids the high-temperature melting process, solves the technical bottleneck of the difficulty in preparing alloy wire due to the brittleness of TiAl alloy at room temperature, and effectively reduces the volatilization of low-melting-point Al elements during the preparation of TiAl alloy wire.

[0155] The diffusion homogenization annealing treatment adopted in the present invention can further diffuse the heterogeneous elements in the TiAl alloy wire, ensure that the composition distribution of the obtained TiAl alloy wire is completely uniform, increase the uniformity of the composition distribution of the wire after melting in the additive manufacturing process, and improve the yield of the printed product.

[0156] The automatic conveying device adopted by the present invention can greatly improve the production efficiency of TiAl alloy wire, effectively reduce its production cost, eliminate manual interference in alloy wire preparation, and further improve the production quality of TiAl alloy wire.

[0157] The present invention can make adaptive adjustments in the pass selection during the preparation and extrusion of TiAl composite wires according to the component ratio and diameter of the target TiAl alloy wire, ensuring that the components of TiAl alloy wires with different compositions are evenly distributed and the diameters meet the requirements, and the wires all have high quality and high performance.

[0158] The tensile strength, yield strength and yield strength ratio of the fine TiAl alloy wire prepared by the present invention gradually increase as the process progresses, and the tensile strength can reach about 700 MPa, and the maximum can approach 720 MPa; similarly, the yield strength ratio is above 0.9, and the maximum can approach 0.985.

[0159] In summary, compared with other traditional methods, the method of the present invention can directly prepare TiAl alloy wires with uniform composition distribution at a lower temperature through multiple twisting, multiple continuous hot drawing and final diffusion homogenization annealing, effectively avoiding the high-temperature melting process. The composition and diameter of the TiAl alloy wire can be designed according to the requirements of the target TiAl alloy wire in the preparation and extrusion process of the TiAl composite wire. It has high flexibility, simple operation, wide applicability and low cost, and is very suitable for large-scale industrial production.

[0160] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. A and B can be singular or plural. Furthermore, the character " / " as used herein generally indicates an "or" relationship between the associated objects, but it may also indicate an "and / or" relationship. For specific understanding, please refer to the context.

[0161] In this disclosure, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0162] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0163] 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 modifications or substitutions that can be easily conceived by a person 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 based on the scope of protection of the claims.

Claims

1. A method for preparing a fine TiAl alloy wire, characterized in that: The preparation method of the fine TiAl alloy wire comprises the following steps: S1. Selection and processing of wire raw materials: According to the composition and mass ratio of the target TiAl alloy wire, a plurality of Ti wires and a plurality of Al wires are selected as wire raw materials; and the wire raw materials are ultrasonically cleaned using commercially available cleaning agents to obtain wire raw materials with clean surfaces; S2. Twisting of wire raw materials: Twisting the wire raw materials in S1 tightly together through a stranding machine to obtain a primary TiAl composite strand with a multi-helical structure; S3, continuous warm drawing of primary TiAl composite strand: the primary TiAl composite strand prepared in S2 is subjected to continuous multi-pass drawing, and the entire process is automatically transmitted to obtain a primary TiAl composite wire; S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together using a twisting machine to obtain secondary TiAl composite twisted wires with a multi-helical structure; S5. Continuous warm drawing of secondary TiAl composite strands: The secondary TiAl composite strands prepared in S4 are subjected to continuous multi-pass drawing, with the entire process being automatically conveyed, to obtain secondary TiAl composite wires; S6. Multiple warm drawing of the TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of the TiAl composite wire, repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, tightly twist the cut TiAl composite wires together through a stranding machine, and then perform the next warm drawing until the target number of passes is completed to obtain the TiAl composite wire; S7, continuous extrusion of TiAl wire: The TiAl composite wire prepared in S6 is continuously drawn and extruded through a continuous wire drawing machine. The extrusion rate of the continuous drawing and extrusion is 1-20 m / min, the wire drawing machine temperature is 600-1000°C, the extrusion die diameter is 0.8-5 mm, and the diameter decreases by 0.2-1 mm each time. The target extrusion pass is matched with the diameter of the TiAl pre-alloyed wire, the extrusion die diameter, and the diameter reduction per pass. The entire process is automatically transmitted until the target pass is stopped to obtain the TiAl alloy wire. The TiAl alloy wire has a tensile strength of 300-650 MPa, a yield strength of 200-550 MPa, and an elongation of 3-10%. S8, diffusion homogenization of TiAl alloy wire: The TiAl alloy wire prepared in S7 is subjected to diffusion homogenization treatment in a vacuum furnace, and after cooling in the furnace, fine TiAl alloy wire with uniform composition is obtained; The continuous multi-pass drawing in S3 and S5 is specifically as follows: first heating to 250-500°C and preheating the drawing die to 250-500°C, then performing continuous multi-pass drawing, with a drawing rate of 5-30m / min, a deformation of 10-20% per drawing, and a total deformation of 20-90% for multi-pass drawing; the tensile strength of the TiAl composite wire is 100-700MPa, the yield strength is 50-600MPa, and the elongation is 6-30%.

2. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The wire material in S1 uses existing brands of wire, or customized design and composition adjustment; the wire material diameter is 1-5mm; the frequency of ultrasonic cleaning is 20-60kHz, and the power is 240-720W.

3. The method for preparing a fine TiAl alloy wire according to claim 1, wherein: In S2 and S4, the speed of the stranding machine is greater than 500 rpm, and the multi-helix structure is a double helix or higher structure; in S2, the length of the stranded wire after stranding is 70-90% of the wire raw material.

4. The method for preparing a fine TiAl alloy wire according to claim 1, wherein: S4 is divided into two or more equal parts.

5. The method for preparing a fine TiAl alloy wire according to claim 1, wherein: The tensile strength of the secondary TiAl composite wire in S5 is 100-700 MPa, the yield strength is 50-600 MPa, and the elongation is 6-30%.

6. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The number of S6 medium temperature drawing passes is 2-10 times, the tensile strength of the TiAl composite wire is 100-700 MPa, the yield strength is 50-600 MPa, and the elongation is 6-30%.

7. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The temperature of the diffusion homogenization treatment in S8 is 600-900℃, the holding time is 60-120min, and the vacuum degree is 10 -1 ~10 -3 Pa, the tensile strength of the fine TiAl alloy wire with uniform composition is 400-750MPa, the yield strength is 300-650MPa, and the elongation is 3-10%.

8. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The preparation method is not only applicable to TiAl alloys, but also to Ti-Al-Nb alloys, Ti-Al-V alloys, Ti-Cu alloys, Ti-Ni alloys, Ti-Fe alloys and Ti-Mo alloys.

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