Preparation method of micro TiAl alloy wire

Abstract

The invention provides a preparation method of a micro TiAl alloy wire, and relates to the technical field of TiAl alloy preparation. The preparation method comprises the steps of raw material selection and treatment of a wire material, raw material twisting of the wire material, continuous warm drawing of a primary TiAl composite stranded wire, twisting of the primary TiAl composite wire, continuous warm drawing of a secondary TiAl composite stranded wire, repeated warm drawing of the TiAl composite wire, continuous extrusion of the TiAl wire and diffusion homogenization of the TiAl alloy wire which are sequentially carried out. According to the preparation method, the TiAl alloy wire with uniformly distributed components can be directly prepared at a lower temperature by combining multiple wire twisting, multiple continuous hot drawing and final diffusion homogenization annealing, the high-temperature melting process is effectively avoided, the components and the diameter of the TiAl alloy wire can be designed according to the requirements of the target TiAl alloy wire for the passes in the preparation and extrusion process of the TiAl composite wire, and the preparation process of the TiAl alloy wire is simplified. The method is high in flexibility, simple to operate, wide in application, low in cost and very suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of TiAl alloy preparation, in particular to a method for preparing a 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 best new lightweight and high-temperature resistant structural material recognized as a substitute for 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 production model of casting, forging and machining can no longer meet the needs of high-efficiency, low-cost complex structure manufacturing. At present, additive manufacturing technology is increasingly used in the manufacture of TiAl alloys in aerospace.

[0003] Since additive manufacturing technology is based on the principle of layer-by-layer accumulation from the bottom up, it has excellent complex molding capabilities. According to different feeding methods, it can be divided into three types: powder laying, powder feeding, and wire feeding. However, powder additive manufacturing technology has high requirements on the quality of powder raw materials, and the deposition speed is slow during the preparation process; and due to the limitations of existing powder making technology, the powder is expensive. In contrast, fused filament additive manufacturing technology using wire as raw material has a fast deposition speed, low production cost, and high molding freedom.

[0004] Therefore, additively manufactured TiAl alloys show 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 plasticity of TiAl alloy at room temperature, it is difficult to draw and form. The existing TiAl alloy fused wire additive manufacturing mostly adopts the "Ti wire + Al wire" double wire feeding method, but its operating mechanism is complex and the equipment cost is high. Even the single wire feeding method uses TiAl composite wire as raw material, which has problems such as complex wire preparation and uneven component distribution. Therefore, it is urgent to invent a preparation method of TiAl alloy wire to meet the high-quality fused wire additive manufacturing needs of TiAl alloy.

[0006] For example: Chinese patent CN106636706A discloses a TiAl alloy wire for 3D printing and a preparation method thereof. The alloy wire is prepared by smelting ingredients, heating and melting, spraying, and drawing. Obviously, it is difficult to achieve uniform distribution of components in the alloy wire prepared by drawing, and the alloy wire preparation cannot be mass-produced and is only suitable for laboratory research. The rotation speed of the copper alloy roller is very high, and it is 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 introduced into assembly, and the Ti / Al composite wire is obtained by rotary forging and drawing in sequence. The Ti / Al composite wire prepared by this method has uneven component distribution and a complicated preparation method, and may have technical defects such as cracks, irregular distribution of streamlines, 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 by 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 fed into the same molten pool for deposition. The operation is difficult, costly, and inefficient, and the distribution of 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 components of the TiAl alloy raw wire, component segregation, poor room temperature plasticity, which lead to the inability to draw wires, 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 components of each part during the deposition process of fused wire additive manufacturing, 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 component distribution, high mechanical properties, low temperature toughness and fatigue strength. The technical scheme is as follows:

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

[0011] S1. Selection and processing of raw materials for wire: according to the mass ratio of the components of the target TiAl alloy wire, select a plurality of corresponding Ti wires and a plurality of Al wires as wire raw materials; and use commercially available cleaning agents to ultrasonically clean the wire raw materials to obtain wire raw materials with clean surfaces;

[0012] S2, twisting of wire raw materials: the wire raw materials in S1 are tightly twisted together by a twisting machine to obtain a primary TiAl composite twisted wire with a multi-helical structure;

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

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

[0015] S5, continuous warm drawing of secondary TiAl composite stranded wire: the secondary TiAl composite stranded wire prepared in S4 is subjected to continuous multi-pass hot drawing, and the whole process is automatically transmitted to obtain secondary TiAl composite wire;

[0016] S6, multiple warm drawing of the TiAl composite wire: according to the uniformity of the TiAl composite wire, the warm drawing passes are determined, and S4-S5 are repeated, that is, the previous TiAl composite wire is divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, and then the next warm drawing is performed until the target pass 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 whole 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 uses existing brands of wire, or a customized design is performed to adjust the composition; the diameter of the wire material is 1-5 mm; the frequency of ultrasonic cleaning is 20-60 kHz, and the power is 240-720 W.

[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 10-20% for each drawing, and a total deformation amount 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%.

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

[0023] Optionally, 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%.

[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 1-20m / min, the wire drawing machine temperature is 600-1000°C, the extrusion die diameter is 0.8-5mm and the diameter decreases by 0.2-1mm each time, 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 300-650MPa, the yield strength is 200-550MPa, 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 above scheme, the present invention proposes a method for preparing fine TiAl alloy wire, which can solve the technical bottleneck of preparing TiAl alloy wire due to poor room temperature plasticity of TiAl alloy and inability to draw and form, and thus solve the problem of limited application of TiAl alloy wire. The traditional process of single-wire additive manufacturing technology using TiAl composite wire as raw material has problems such as complex wire preparation and uneven finished product components. The fine TiAl alloy wire obtained by the present invention has uniform composition and organization, dense structure, smooth surface, and no defects such as oxidation, cracking, and pores. The performance of each part of the fused wire additive manufacturing product using this as raw material is stable and consistent, providing high-quality raw materials 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, and has no special restrictions on the raw material brand, composition, etc. The range of selectable raw materials is wide, and 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 a single metal wire of the alloy to be compounded, and forms a tight spiral structure with two or more of the single metal wires through a twisting method. Combined with a multi-pass continuous warm drawing process, the pre-alloying of the single metal alloy 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 by the present invention can improve the plastic deformation ability of the wire during the drawing process, reduce the deformation resistance, ensure that no cracking, wire breakage, etc. occur during the deformation process, and can effectively reduce the number of drawing passes and reduce the internal stress of the prepared wire, so that the preparation efficiency of the wire is significantly improved.

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

[0034] The diffusion homogenization annealing treatment adopted in the present invention can make the heterogeneous elements in the TiAl alloy wire further diffuse with each other, ensure that the obtained TiAl alloy wire has a completely uniform distribution of components, increase the uniformity of the distribution of components after the wire is melted in the additive manufacturing process, and improve the yield rate of printed products.

[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 the interference of manual labor in the preparation of alloy wire, 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 the TiAl composite wire according to the component ratio and diameter of the target TiAl alloy wire, ensuring that the components of the TiAl alloy wires with different components are evenly distributed and the diameters meet the requirements, and the wires 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 with the progress of the process, and the tensile strength can reach about 700MPa, and the maximum can be close to 720MPa; similarly, the yield strength ratio is above 0.9, and the maximum can be close to 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 wire 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 for the preparation of the TiAl composite wire and the passes in the extrusion process. 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 It 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 "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0043] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same. "of", "corresponding" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express 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 more clear, 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 raw materials for wire: according to the mass ratio of the components of the target TiAl alloy wire, select a plurality of corresponding Ti wires and a plurality of Al wires as wire raw materials; and use commercially available cleaning agents to ultrasonically clean the wire raw materials to obtain wire raw materials with clean surfaces;

[0048] S2, twisting of wire raw materials: the wire raw materials in S1 are tightly twisted together by a twisting machine to obtain a primary TiAl composite twisted wire with a multi-helical structure;

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

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

[0051] S5, continuous warm drawing of secondary TiAl composite stranded wire: the secondary TiAl composite stranded wire prepared in S4 is subjected to continuous multi-pass hot drawing, and the whole process is automatically transmitted to obtain secondary TiAl composite wire;

[0052] S6, multiple warm drawing of the TiAl composite wire: according to the uniformity of the TiAl composite wire, the warm drawing passes are determined, and S4-S5 are repeated, that is, the previous TiAl composite wire is divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, and then the next warm drawing is performed until the target pass 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 whole 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 customizes the design and composition; 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, 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.

[0057] In particular, the continuous multi-pass hot drawing in S3 and S5 is 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 10-20% for each drawing, and a total deformation amount 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 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 by 0.2-1 mm each time, the extrusion target pass matches the TiAl pre-alloyed wire diameter, the extrusion die diameter and the diameter reduction per pass, and 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°C, the holding time is 60-120 min, 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 content of the TiAl alloy wire is as follows: Ti 52%, Al 48% by mass percentage; the method for preparing the fine TiAl alloy wire comprises the following steps:

[0066] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, 5 Ti wires and 5 Al wires with a diameter of 2 mm were selected as raw materials for wires; and commercially available cleaning agents were used to ultrasonically clean the raw materials for wires, respectively, at a frequency of 40 kHz and a power of 360 W to obtain raw materials for wires with clean surfaces;

[0067] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 800 rpm, and the length of the twisted wire is 80% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a double helix structure;

[0068] 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, first heated to 400°C and the wire drawing die is preheated to 380°C, and then continuously drawn in multiple passes, with a drawing rate of 9m / min, a deformation of 12% for each drawing, and a total deformation of 60% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the primary TiAl composite wire has a tensile strength of 310MPa, a yield strength of 232MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 3.10GPa·%;

[0069] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into two equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 1000 rpm, and the length of the twisted wires is 75% of half of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a double helix structure;

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

[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 is continuously drawn and extruded through a continuous wire drawing machine. The extrusion rate of the continuous drawing and extrusion is 15 m / min, the temperature of the wire drawing machine is 850°C, the diameter of the extrusion die is 3 mm and the diameter decreases by 0.5 mm each time. The extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the diameter of the extrusion die and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass stops to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 512 MPa, the yield strength is 460 MPa, the yield strength ratio is 0.898, the elongation is 6%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 668MPa, a yield strength of 621MPa, a yield strength ratio of 0.930, an elongation of 5%, and a strength-ductility product of 3.34GPa·%.

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

[0075] Example 2

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

[0077] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, 6 Ti wires and 4 Al wires with a diameter of 3 mm were selected as raw materials for wires; and commercially available cleaning agents were used to ultrasonically clean the raw materials for wires, respectively, at a frequency of 600 kHz and a power of 720 W to obtain raw materials for wires with clean surfaces;

[0078] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 500 rpm, and the length of the twisted wire after twisting is 85% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a multi-helical structure;

[0079] 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, first heated to 300°C and the wire drawing die is preheated to 270°C, and then continuously drawn in multiple passes, with a drawing rate of 6m / min, a deformation of 10% each time, and a total deformation of 50% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the tensile strength of the primary TiAl composite wire is 412MPa, the yield strength is 288MPa, the yield strength ratio is 0.699, the elongation is 14.1%, and the strength-ductility product is 5.81GPa·%;

[0080] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 800 rpm, and the length of the twisted wires is 80% of one third of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a multi-helical structure;

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

[0082] S6. Multiple warm drawing of TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of TiAl composite wire, and the continuous warm drawing passes are 4 times. Repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, and use a stranding machine to tightly twist the cut TiAl composite wires together before the next warm drawing. The whole process is automatically transmitted to obtain TiAl composite wire; the tensile strength of the TiAl composite wire is 447MPa, the yield strength is 366MPa, the yield strength ratio is 0.819, the elongation is 7%, and the strength-ductility product is 3.13GPa·%;

[0083] 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 18 m / min, the temperature of the wire drawing machine is 900°C, the diameter of the extrusion die is 4 mm and the diameter decreases by 0.2 mm each time, the extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the extrusion die diameter and the diameter reduction of each pass, the whole process is automatically transmitted until the target pass is stopped, and the TiAl alloy wire is obtained; the tensile strength of the TiAl alloy wire is 580 MPa, the yield strength is 527 MPa, the yield strength ratio is 0.909, the elongation is 7%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 693MPa, a yield strength of 648MPa, a yield strength ratio of 0.935, an elongation of 6.8%, and a strength-ductility product of 4.71GPa·%.

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

[0086] Comparative Example 1

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

[0088] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, 5 Ti wires and 5 Al wires with a diameter of 2 mm were selected as raw materials for wires; and commercially available cleaning agents were used to ultrasonically clean the raw materials for wires, respectively, at a frequency of 40 kHz and a power of 360 W to obtain raw materials for wires with clean surfaces;

[0089] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 800 rpm, and the length of the twisted wire is 80% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a double helix structure;

[0090] 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, first heated to 400°C and the wire drawing die is preheated to 380°C, and then continuously drawn in multiple passes, with a drawing rate of 9m / min, a deformation of 12% for each drawing, and a total deformation of 60% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the primary TiAl composite wire has a tensile strength of 310MPa, a yield strength of 232MPa, a yield strength ratio of 0.748, an elongation of 10%, and a strength-ductility product of 3.10GPa·%;

[0091] S4. Continuous extrusion of TiAl wire: The secondary TiAl composite wire prepared in S5 is continuously drawn and extruded through a continuous wire drawing machine. The extrusion rate of the continuous drawing and extrusion is 15 m / min, the temperature of the wire drawing machine is 850°C, the diameter of the extrusion die is 3 mm and the diameter decreases by 0.5 mm each time. The extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the extrusion die diameter and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass stops to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 430 MPa, the yield strength is 365 MPa, the yield strength ratio is 0.849, the elongation is 6%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 550MPa, a yield strength of 496MPa, a yield strength ratio of 0.902, an elongation of 2%, and a strength-ductility product of 1.10GPa·%.

[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 once, the wires of different components are mixed unevenly, and the prepared fine TiAl alloy wire has the problem of uneven composition and organizational morphology.

[0094] Comparative Example 2

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

[0096] S1. Selection and processing of raw materials for wire: According to the mass ratio of the target TiAl alloy wire, 6 Ti wires and 4 Al wires with a diameter of 3 mm were selected as raw materials for wire; and the raw materials for wire were ultrasonically cleaned with commercially available cleaning agents, with a frequency of 60 kHz and a power of 720 W to obtain raw materials for wire with clean surfaces;

[0097] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 500 rpm, and the length of the twisted wire after twisting is 85% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a multi-helical structure;

[0098] 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, first heated to 300°C and the wire drawing die is preheated to 270°C, and then continuously drawn in multiple passes, with a drawing rate of 6m / min, a deformation of 10% each time, and a total deformation of 50% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the tensile strength of the primary TiAl composite wire is 412MPa, the yield strength is 288MPa, the yield strength ratio is 0.699, the elongation is 14.1%, and the strength-ductility product is 5.81GPa·%;

[0099] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 800 rpm, and the length of the twisted wires is 80% of one third of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a multi-helical structure;

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

[0101] S6. Multiple warm drawing of TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of TiAl composite wire, and the continuous warm drawing passes are 4 times. Repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, and use a stranding machine to tightly twist the cut TiAl composite wires together before the next warm drawing. The whole process is automatically transmitted to obtain TiAl composite wire; the tensile strength of the TiAl composite wire is 447MPa, the yield strength is 366MPa, the yield strength ratio is 0.819, the elongation is 7%, and the strength-ductility product is 3.13GPa·%;

[0102] 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 18 m / min, the temperature of the wire drawing machine is 1200°C, the diameter of the extrusion die is 4 mm and the diameter decreases by 0.2 mm each time. The extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the extrusion die diameter and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass is stopped to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 620 MPa, the yield strength is 576 MPa, the yield strength ratio is 0.929, the elongation is 2%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 705MPa, a yield strength of 691MPa, a yield strength ratio of 0.980, an elongation of 0.5%, and a strength-ductility product of 0.35GPa·%.

[0104] The diameter of the fine TiAl alloy wire obtained in this comparative example is 3 mm. Due to the excessively 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 wire breakage, cracking, oxidation and other problems during the wire preparation process. Therefore, in the actual operation process, it is necessary to combine the target TiAl alloy wire performance and reasonably set each parameter to obtain high-quality TiAl alloy wire with uniform composition and organizational morphology, dense structure, smooth surface, and no defects such as oxidation, cracking, and pores.

[0106] Example 3

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

[0108] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, three Ti wires and three Al wires with a diameter of 4 mm were selected as raw materials for wires; and commercially available cleaning agents were used to ultrasonically clean the raw materials for wires, respectively, at a frequency of 20 kHz and a power of 240 W to obtain raw materials for wires with clean surfaces;

[0109] S2, twisting of wire raw materials: the wire raw materials in S1 are tightly twisted together by a twisting machine, the twisting machine speed is 1000 rpm, and the length of the twisted wire is 75% of the wire raw materials, to obtain a primary TiAl composite twisted wire with a multi-helical structure;

[0110] 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, first heated to 480°C and the wire drawing die is preheated to 450°C, and then continuously drawn in multiple passes, with a drawing rate of 20m / min, a deformation of 15% each time, and a total deformation of 60% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the primary TiAl composite wire has a tensile strength of 452MPa, a yield strength of 325MPa, a yield strength ratio of 0.719, an elongation of 12.9%, and a strength-ductility product of 8.09GPa·%;

[0111] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into four equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 1500rmp, and the length of the twisted wires is 70% of one quarter of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires 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, first heated to 480°C and the wire drawing die was preheated to 450°C, and then continuously drawn in multiple passes, with a drawing rate of 18m / min, a deformation of 14% each time, and a total deformation of 70% for multiple drawing passes; the whole process was automatically transmitted to obtain secondary TiAl composite wires; the tensile strength of the secondary TiAl composite wires was 483MPa, the yield strength was 376MPa, the yield strength ratio was 0.778, the elongation was 8%, and the strength-ductility product was 3.86GPa·%;

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

[0114] 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 10 m / min, the temperature of the wire drawing machine is 770°C, the diameter of the extrusion die is 5 mm and the diameter decreases by 0.5 mm each time. The target extrusion pass is matched with the diameter of the TiAl pre-alloyed wire, the diameter of the extrusion die and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass stops to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 597 MPa, the yield strength is 525 MPa, the yield strength ratio is 0.879, the elongation is 5%, and the strength-ductility product is 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, a 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 organizational morphology, dense structure, smooth surface, no defects such as oxidation, cracking, pores, etc., and no broken wire occurs during the preparation process.

[0117] Example 4

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

[0119] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, 5 Ti wires and 5 Al wires with a diameter of 2 mm were selected as raw materials for wires; and the raw materials for wires were ultrasonically cleaned using commercially available cleaning agents, with a frequency of 60 kHz and a power of 720 W to obtain raw materials for wires with clean surfaces;

[0120] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 800 rpm, and the length of the twisted wire is 80% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a double helix structure;

[0121] 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, first heated to 400°C and the drawing die is preheated to 380°C, and then continuously drawn in multiple passes, with a drawing rate of 9m / min, a deformation of 12% for each drawing, and a total deformation of 60% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the tensile strength of the primary TiAl composite wire is 413MPa, the yield strength is 293MPa, the yield strength ratio is 0.709, the elongation is 13.8%, and the strength-ductility product is 5.70GPa·%;

[0122] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into two equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 1000 rpm, and the length of the twisted wires is 75% of half of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a double helix structure;

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

[0124] S6. Multiple warm drawing of TiAl composite wire: the number of warm drawing passes is determined according to the uniformity of the TiAl composite wire, and the continuous warm drawing passes are 3 times. S4-S5 are repeated, that is, the previous TiAl composite wire is divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, and then the next warm drawing is carried out until the target pass is completed to obtain the TiAl composite wire; the tensile strength of the TiAl composite wire is 466MPa, the yield strength is 370MPa, the yield strength ratio is 0.794, the elongation is 7.3%, and the strength-ductility product is 3.40GPa·%;

[0125] S7. Continuous extrusion of TiAl wire: The secondary TiAl composite wire prepared in S5 is continuously drawn and extruded through a continuous wire drawing machine. The extrusion rate of the continuous drawing and extrusion is 15 m / min, the temperature of the wire drawing machine is 850°C, the diameter of the extrusion die is 3 mm and the diameter decreases by 0.5 mm each time. The extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the diameter of the extrusion die and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass is stopped to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 584 MPa, the yield strength is 513 MPa, the yield strength ratio is 0.878, the elongation is 8.8%, and the strength-ductility product is 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, a 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 organizational morphology, dense structure, smooth surface, no defects such as oxidation, cracking, pores, etc., and no broken wire occurs during the preparation process.

[0128] Example 5

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

[0130] S1. Selection and processing of raw materials for wires: According to the mass ratio of the target TiAl alloy wire components, three Ti wires and three Al wires with a diameter of 4 mm were selected as raw materials for wires; and commercially available cleaning agents were used to ultrasonically clean the raw materials for wires, respectively, at a frequency of 20 kHz and a power of 240 W to obtain raw materials for wires with clean surfaces;

[0131] S2, twisting of wire raw materials: the wire raw materials in S1 are tightly twisted together by a twisting machine, the twisting machine speed is 1000 rpm, and the length of the twisted wire is 75% of the wire raw materials, to obtain a primary TiAl composite twisted wire with a multi-helical structure;

[0132] 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, first heated to 480°C and the wire drawing die is preheated to 450°C, and then continuously drawn in multiple passes, with a drawing rate of 20m / min, a deformation of 15% each time, and a total deformation of 60% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the primary TiAl composite wire has a tensile strength of 488MPa, a yield strength of 356MPa, a yield strength ratio of 0.730, an elongation of 12.5%, and a strength-ductility product of 6.10GPa·%;

[0133] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into four equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 1500rmp, and the length of the twisted wires is 70% of one quarter of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a multi-helical structure;

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

[0135] S6. Multiple warm drawing of TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of TiAl composite wire, and the continuous warm drawing passes are 3 times. Repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, and use a stranding machine to tightly twist the cut TiAl composite wires together before the next warm drawing. Until the target pass is completed, the whole process is automatically transmitted to obtain TiAl composite wire; the tensile strength of TiAl composite wire is 542MPa, the yield strength is 439MPa, the yield strength ratio is 0.810, the elongation is 6.8%, and the strength-ductility product is 3.69GPa·%;

[0136] 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 10 m / min, the temperature of the wire drawing machine is 770°C, the diameter of the extrusion die is 5 mm and the diameter decreases by 0.5 mm each time, the extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the extrusion die diameter and the diameter reduction of each pass, the whole process is automatically transmitted until the target pass is stopped, and the TiAl alloy wire is obtained; the tensile strength of the TiAl alloy wire is 633 MPa, the yield strength is 548 MPa, the yield strength ratio is 0.866, the elongation is 5%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 670MPa, a yield strength of 626MPa, a yield strength ratio of 0.934, an elongation of 5%, and a strength-ductility product of 3.35GPa·%.

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

[0139] Example 6

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

[0141] S1. Selection and processing of raw materials for wire: According to the mass ratio of the target TiAl alloy wire, 6 Ti wires and 4 Al wires with a diameter of 3 mm were selected as raw materials for wire; and the raw materials for wire were ultrasonically cleaned with commercially available cleaning agents, with a frequency of 60 kHz and a power of 720 W to obtain raw materials for wire with clean surfaces;

[0142] S2, twisting of raw materials of wire: the raw materials of wire in S1 are tightly twisted together by a twisting machine, the speed of the twisting machine is 500 rpm, and the length of the twisted wire after twisting is 85% of the raw materials of wire, so as to obtain a primary TiAl composite twisted wire with a multi-helical structure;

[0143] 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, first heated to 300°C and the wire drawing die is preheated to 270°C, and then continuously drawn in multiple passes, with a drawing rate of 6m / min, a deformation of 10% for each drawing, and a total deformation of 50% for multiple drawing passes; the whole process is automatically transmitted to obtain a primary TiAl composite wire; the tensile strength of the primary TiAl composite wire is 243MPa, the yield strength is 158MPa, the yield strength ratio is 0.650, the elongation is 15%, and the strength-ductility product is 3.65GPa·%;

[0144] S4, twisting of primary TiAl composite wires: the primary TiAl composite wires prepared in S3 are divided into three equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, the twisting machine speed is 800 rpm, and the length of the twisted wires is 80% of one third of the primary TiAl composite wires, so as to obtain secondary TiAl composite twisted wires with a multi-helical structure;

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

[0146] S6. Multiple warm drawing of TiAl composite wire: Determine the number of warm drawing passes according to the uniformity of TiAl composite wire, and the continuous warm drawing passes are 5 times. Repeat S4-S5, that is, divide the previous TiAl composite wire into multiple equal parts along the cross section, and use a stranding machine to tightly twist the cut TiAl composite wires together before the next warm drawing. The whole process is automatically transmitted to obtain TiAl composite wire. The tensile strength of the TiAl composite wire is 320MPa, the yield strength is 252MPa, the yield strength ratio is 0.788, the elongation is 7.4%, and the strength-ductility product is 2.37GPa·%;

[0147] 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 18 m / min, the temperature of the wire drawing machine is 900°C, the diameter of the extrusion die is 4 mm and the diameter decreases by 0.2 mm each time. The extrusion target pass is matched with the diameter of the TiAl pre-alloyed wire, the diameter of the extrusion die and the diameter reduction of each pass. The whole process is automatically transmitted until the target pass is stopped to obtain the TiAl alloy wire. The tensile strength of the TiAl alloy wire is 556 MPa, the yield strength is 511 MPa, the yield strength ratio is 0.919, the elongation is 7%, and the strength-ductility product is 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, a fine TiAl alloy wire with uniform composition was obtained; the fine TiAl alloy wire with uniform composition had a tensile strength of 662MPa, a yield strength of 615MPa, a yield strength ratio of 0.929, an elongation of 7.2%, and a strength-ductility product of 4.77GPa·%.

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

[0150] The above scheme, the present invention proposes a method for preparing fine TiAl alloy wire, which can solve the technical bottleneck of preparing TiAl alloy wire due to poor room temperature plasticity of TiAl alloy and inability to draw and form, and thus solve the problem of limited application of TiAl alloy wire. The traditional process of single-wire additive manufacturing technology using TiAl composite wire as raw material has problems such as complex wire preparation and uneven finished product components. The fine TiAl alloy wire obtained by the present invention has uniform composition and organization, dense structure, smooth surface, and no defects such as oxidation, cracking, and pores. The performance of each part of the fused wire additive manufacturing product using this as raw material is stable and consistent, providing high-quality raw materials 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, and has no special restrictions on the raw material brand, composition, etc. The range of selectable raw materials is wide, and 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 a single metal wire of the alloy to be compounded, and forms a tight spiral structure with two or more of the single metal wires through a twisting method. Combined with a multi-pass continuous warm drawing process, the pre-alloying of the single metal alloy 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 by the present invention can improve the plastic deformation ability of the wire during the drawing process, reduce the deformation resistance, ensure that no cracking, wire breakage, etc. occur during the deformation process, and can effectively reduce the number of drawing passes and reduce the internal stress of the prepared wire, so that the preparation efficiency of the wire is significantly improved.

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

[0155] The diffusion homogenization annealing treatment adopted in the present invention can make the heterogeneous elements in the TiAl alloy wire further diffuse with each other, ensure that the obtained TiAl alloy wire has a completely uniform distribution of components, increase the uniformity of the distribution of components after the wire is melted in the additive manufacturing process, and improve the yield rate of printed products.

[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 the interference of manual labor in the preparation of alloy wire, 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 the TiAl composite wire according to the component ratio and diameter of the target TiAl alloy wire, ensuring that the components of the TiAl alloy wires with different components are evenly distributed and the diameters meet the requirements, and the wires 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 with the progress of the process, and the tensile strength can reach about 700MPa, and the maximum can be close to 720MPa; similarly, the yield strength ratio is above 0.9, and the maximum can be close to 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 wire 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 for the preparation of the TiAl composite wire and the passes in the extrusion process. 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" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0161] In the present invention, "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 items or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[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 is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope 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 raw materials for wire: according to the mass ratio of the components of the target TiAl alloy wire, select a plurality of corresponding Ti wires and a plurality of Al wires as wire raw materials; and use commercially available cleaning agents to ultrasonically clean the wire raw materials to obtain wire raw materials with clean surfaces; S2, twisting of wire raw materials: the wire raw materials in S1 are tightly twisted together by a twisting machine to obtain a primary TiAl composite twisted wire with a multi-helical structure; S3, continuous warm drawing of a TiAl composite strand: the TiAl composite strand prepared in S2 is subjected to continuous multi-pass hot drawing, and the whole process is automatically transmitted to obtain a TiAl composite wire; S4, twisting of primary TiAl composite wires: dividing the primary TiAl composite wires prepared in S3 into multiple equal parts along the cross section, and tightly twisting the cut TiAl composite wires together by a twisting machine to obtain secondary TiAl composite twisted wires with a multi-helical structure; S5, continuous warm drawing of secondary TiAl composite stranded wire: the secondary TiAl composite stranded wire prepared in S4 is subjected to continuous multi-pass hot drawing, and the whole process is automatically transmitted to obtain secondary TiAl composite wire; S6, multiple warm drawing of the TiAl composite wire: according to the uniformity of the TiAl composite wire, the warm drawing passes are determined, and S4-S5 are repeated, that is, the previous TiAl composite wire is divided into multiple equal parts along the cross section, and the cut TiAl composite wires are tightly twisted together by a twisting machine, and then the next warm drawing is performed until the target pass 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, and the whole process is automatically transmitted until the target pass is stopped to obtain a TiAl alloy wire; 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.

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 customizes the design and composition; 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, characterized in that: In S2 and S4, the speed of the stranding machine 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 above a double helix.

4. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: 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 continuous multi-pass drawing, the drawing rate is 5-30m / min, the deformation of each drawing is 10-20%, and the total deformation of multi-pass drawing is 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%.

5. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: S4 can be divided into two or more equal parts.

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

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

8. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The extrusion rate of continuous drawing extrusion in S7 is 1-20m / min, the temperature of the wire drawing machine is 600-1000℃, the diameter of the extrusion die is 0.8-5mm and the diameter decreases by 0.2-1mm each time, the extrusion target pass matches the diameter of the TiAl pre-alloyed wire, the extrusion die diameter and the diameter reduction of each pass, and the tensile strength of the TiAl alloy wire is 300-650MPa, the yield strength is 200-550MPa, and the elongation is 3-10%.

9. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: The temperature of 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%.

10. The method for preparing a fine TiAl alloy wire according to claim 1, characterized in that: 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.

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