Ultrafine tantalum metal micro-wire and preparation method thereof

Abstract

The present application relates to a kind of superfine tantalum metal microfilament and its preparation method, belong to non-ferrous metal processing field, at least one of the problems in the preparation of 0.10mm below, especially 0.05mm below tantalum microfilament in prior art, such as high wire breakage rate, low yield, size precision difficult control etc.It is prepared that a kind of superfine tantalum metal microfilament, comprising: coarse wire continuous drawing process: the tantalum wire with diameter Φ2.0mm~Φ2.5mm, diameter is reduced to Φ0.50mm~Φ0.65mm;Middle drawing process: after the tantalum wire of coarse wire drawing, diameter is reduced to Φ0.18mm~Φ0.30mm;Precise microfilament drawing process: after the tantalum wire of middle drawing process, diameter is finally reduced to Φ0.025mm~Φ0.055mm.The present application realizes the continuous stable drawing of superfine tantalum metal microfilament, and the wire breakage rate is 0 per kilometer, with excellent mechanical properties, high size precision and good surface quality.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal processing technology, and in particular to an ultrafine tantalum metal microwire and its preparation method. Background Technology

[0002] Tantalum metal possesses excellent properties such as high melting point, strong corrosion resistance, and good biocompatibility, making its microfilaments widely used in miniaturized electronic devices, high-end smartphones, tablets, and medical applications. With the miniaturization of components, increasingly stringent requirements have been placed on the individual length, diameter, strength, ductility, and surface uniformity of tantalum metal microfilaments. However, the high melting point, high room temperature brittleness, and easy oxidation at high temperatures of tantalum metal microfilaments make the drawing of ultrafine filaments a recognized technical challenge.

[0003] For tantalum metal microwires, existing technologies have the following problems: First, tantalum metal is extremely prone to wire breakage during the drawing process, especially ultrafine wires below 0.10 mm, particularly below 0.05 mm. As the wire diameter continues to decrease, the drawing difficulty increases dramatically, making wire breakage very easy. Second, there is no mature preparation process for ultrafine tantalum metal microwires below 0.10 mm, especially below 0.05 mm. High wire breakage rate, low yield, and difficulty in controlling dimensional accuracy have always been the main bottlenecks restricting its industrialization. Third, existing microwire technologies are all designed for other metal materials, such as beryllium copper alloys, stainless steel, and tungsten wires. The physical properties and processing behavior of these materials are significantly different from tantalum metal, and their preparation processes cannot be directly applied to tantalum metal.

[0004] Therefore, developing a method for preparing ultrafine tantalum metal microwires with diameters below 0.10 mm, especially below 0.05 mm, with continuous wire lengths over kilometers, high precision, and high yield is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide an ultrafine tantalum metal microwire and its preparation method, so as to solve at least one of the problems existing in the preparation of tantalum microwires below 0.10 mm, especially below 0.05 mm, such as high wire breakage rate, low yield, and difficulty in controlling dimensional accuracy.

[0006] The objective of this invention is achieved through the following technical solution: This invention provides a method for preparing ultrafine tantalum metal microwires, comprising: Continuous drawing process for coarse wire: Tantalum wire with a diameter of Φ2.0mm~Φ2.5mm is continuously drawn in N1 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter to Φ0.50mm~Φ0.65mm; wherein, the single-pass die processing rate X iThe percentage is controlled between 12% and 20%, the total number of passes N1 is 17 to 20, and i is a positive integer from 1 to N1; Intermediate drawing process: The tantalum wire, after the continuous drawing process of the coarse wire, is continuously drawn in N2 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter to Φ0.18mm~Φ0.30mm; where the single-pass die processing rate X j The percentage is controlled between 10% and 15%, the total number of passes N2 is 14 to 19, and j is a positive integer from 1 to N2; Precision micro-wire drawing process: The tantalum wire after the intermediate drawing process is continuously drawn in N3 passes using a non-slip wire drawing machine and diamond dies, reducing the diameter to Φ0.025mm~Φ0.055mm; where the single-pass die processing rate X k Controlled within 8%~16%, mold deformation angle θ k The sizing zone length L is controlled within the range of 9° to 14°. k The drawing diameter is controlled within 10μm to 30μm, the drawing tension is controlled within 6N to 12N, the linear speed is controlled within 0.8m / s to 1.8m / s, the total number of passes N3 is 16 to 21, and k is a positive integer from 1 to N3.

[0007] Furthermore, in the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from below Φ2.4mm to below Φ0.63mm, N1=17~20, and the single-pass die processing rate X i Control will be implemented in the following three stages: In the first stage, the number of passes a1 is 3~8, X i =18%~20%; In the second stage, the number of passes a2 is 4~10, X i =15%~17%; In the third stage, the number of passes a3 is 4~10, X i =12%~15%; And a1+a2+a3=N1.

[0008] Furthermore, in the intermediate drawing process, when the tantalum wire diameter is drawn from below Φ0.63mm to below Φ0.27mm, N2 = 14~19, and the single-pass die processing rate X j Control will be implemented in the following three stages: In the first stage, the number of passes b1 is 3-8, X j =14%~15%; In the second stage, the number of passes b2 is 4~10, X j =12%~13%; In the third stage, the number of passes (b3) is 3-8, X j =10%~12%; And b1+b2+b3=N2.

[0009] Furthermore, in the precision micro-wire drawing process, when the tantalum wire diameter is drawn from below Φ0.27mm to below Φ0.052mm, N3 = 16~21, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: In the first stage, the number of rounds c1 is 2~12, X k =15%~16%, θ k =12°~14°, L k =10~14μm; In the second stage, the number of passes c2 is 4~8, X k =11%~14%, θ k =10°~12°, L k =15~19μm; In the third stage, the number of passes (c3) is 5-13, X k =8%~13%, θ k =9°~11°, L k =20~25μm; And c1+c2+c3=N3.

[0010] Furthermore, in the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.59mm~Φ0.63mm, N1=17, and the single-pass die processing rate X i Control will be implemented in the following three stages: Phase 1, Courses 1-6, X i =18%~20%, i=1~6; Phase Two, Courses 7-12, X i =16%~17%, i=7~12; Phase 3, Courses 13-17, X i =14%~15%, i=13~17; And / or, In the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.54mm~Φ0.58mm, N1=18, and the single-pass die processing rate X i Control will be implemented in the following three stages: Phase 1, Courses 1-3, X i =18%~20%, i=1~3; Second stage, courses 4-10, X i =15%~16%, i=4~10; Phase 3, Courses 11-18, X i =12%~13%, i=11~18.

[0011] Furthermore, in the intermediate drawing process, when the tantalum wire diameter is drawn from Φ0.59mm~Φ0.63mm to Φ0.23mm~Φ0.27mm, N2=15, and the single-pass die processing rate X j Control will be implemented in the following three stages: Phase 1, Courses 1-5, X j =14%~15%, j=1~5; Second stage, courses 6-10, X j =12%~13%, j=6~10; Phase 3, Courses 11-15, X j =11%~12%, j=11~15.

[0012] And / or, In the aforementioned drawing process, when the tantalum wire diameter is drawn from Φ0.54mm~Φ0.58mm to Φ0.18mm~Φ0.22mm, N2=18, and the single-pass die processing rate X j Control will be implemented in the following three stages: Phase 1, Courses 1-6, X j =14%~15%, j=1~6; Phase Two, Courses 7-15, X j =12%~13%, j=7~15; Phase 3, Courses 16-18, X j =10%~11%, j=16~18.

[0013] Furthermore, in the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.048mm~Φ0.052mm, N3=17, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-2, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~2; Second stage, courses 3-6, X k =13%~14%, θ k =10°~12°, L k=15~17μm, k=3~6; Phase 3, Courses 7-17, X k =12%~13%, θ k =9°~10°, L k =20~25μm, k=7~17; And / or, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.043mm~Φ0.047mm, N3=18, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-5, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~5; Second stage, courses 6-10, X k =11%~12%, θ k =11°~12°, L k =15~18μm, k=6~10; Phase 3, Courses 11-18, X k =9%~10%, θ k =10°~11°, L k =20~23μm, k=11~18; And / or, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.028mm~Φ0.032mm, N3=20, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-10, X k =15%~16%, θ k =12°~13°, L k =10~13μm, k=1~10; Phase Two, Courses 11-15, X k =11%~12%, θ k =10°~12°, L k =15~18μm, k=11~15; Phase 3, Courses 16-20, X k=8%~9%, θ k =10°~11°, L k =20~23μm, k=16~20.

[0014] Furthermore, prior to the continuous drawing process of the coarse wire, the following steps are also included: Tantalum rods are manufactured using electron beam melting and spin cutting. The tantalum bar is rolled using a rhombohedral die system; Vacuum heat treatment is performed after rolling; After vacuum heat treatment, the surface is treated with molten salt using a NaCl-KCl mixed salt bath.

[0015] Furthermore, the mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (3~7):(1~4); And / or, the temperature of the molten salt treatment is 600~1000℃; And / or, the molten salt treatment time is 2 to 10 minutes.

[0016] This invention provides an ultrafine tantalum metal microwire, which is prepared using the above-described method for preparing ultrafine tantalum metal microwire.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) In the preparation method of the present invention, based on the specific material characteristics of tantalum metal, such as high melting point, high room temperature brittleness, and easy work hardening, the total deformation is reasonably distributed to each pass of the three processes by coarse wire continuous drawing, intermediate drawing, and precision micro wire drawing, as well as by optimizing and controlling the appropriate number of passes and the processing rate of each pass. In the coarse drawing stage, the characteristic that tantalum metal still has good plasticity in a relatively coarse state is utilized, and the diameter is rapidly reduced by using an appropriate number of passes and a large single-pass processing rate; in the intermediate drawing stage, an appropriate number of passes is used and the single-pass processing rate is appropriately reduced to avoid work hardening accumulating too quickly. In particular, in the precision micro wire drawing stage, the wire diameter has been refined to below 0.30 mm. At this time, the absolute load-bearing capacity of tantalum metal drops sharply, and each process parameter is extremely sensitive. Any deviation of any parameter may lead to wire breakage. To address this challenge, this invention employs an appropriate number of passes in the fine drawing stage and precisely controls the single-pass processing rate, deformation angle, sizing zone length, tension, and linear speed, ensuring that deformation energy is released uniformly in each pass. This avoids wire breakage caused by excessively rapid work hardening, stress concentration, or parameter fluctuations, significantly reducing the wire breakage rate, improving the yield, and achieving kilometer-level continuous non-breaking wire production.

[0018] (2) In the preparation method of the present invention, based on the specific material characteristics of tantalum metal, such as high viscosity and easy adhesion and wear with the mold, the rough drawing and intermediate drawing processes adopt a direct-feed wire drawing machine in combination with a tungsten steel mold. The good toughness of the tungsten steel mold can withstand a moderate to large deformation load, thereby achieving rapid diameter reduction. In the precision micro-wire drawing stage, a non-slip wire drawing machine in combination with a diamond mold is used. The advantages of the non-slip wire drawing machine, such as independent servo drive and real-time tension monitoring, are used to eliminate sliding friction and tension fluctuations. The high hardness and excellent wear resistance of the diamond mold are used to maintain the stability of the hole diameter in the sizing zone for a long time, avoiding wire diameter drift caused by mold wear. However, relying solely on the selection of mold and wire drawing machine is still insufficient to achieve stable drawing and high forming accuracy of ultrafine tantalum micro-wires. It is also necessary to coordinate the control of parameters such as pass allocation, processing rate, deformation angle, sizing zone length, tension, and linear speed.

[0019] This invention achieves a reasonable distribution of deformation by optimizing the allocation of the total number of passes and the processing rate per pass in each process. In the rough drawing stage, an appropriate number of passes are used in conjunction with a larger processing rate per pass for rapid diameter reduction; in the intermediate drawing stage, an appropriate number of passes are used and the processing rate per pass is appropriately reduced to avoid excessive accumulation of work hardening; in the precision micro-wire drawing stage, an appropriate number of passes are used in conjunction with an appropriate processing rate per pass for precision forming.

[0020] Especially in the precision micro-wire drawing stage, where the wire diameter has been refined to a certain extent, this invention coordinates the single-pass processing rate, die deformation angle, sizing zone length, drawing tension, and linear speed: the single-pass processing rate is controlled within an optimized range to ensure that the deformation amount in each pass does not exceed the wire's load-bearing limit; the die deformation angle is controlled within an optimized range to ensure a smooth metal deformation path and uniform stress distribution in the deformation zone, matching the processing rate and guaranteeing uniform metal flow and wire roundness; the sizing zone length is controlled within an optimized range to reduce contact friction between the wire and the die, further suppressing surface adhesion and scratches, while avoiding friction accumulation due to an excessively long sizing zone; the drawing tension and linear speed are coordinated and kept stable to avoid diameter deviations caused by tension fluctuations or speed changes. These parameters work together to ensure uniform release of deformation energy in each pass, avoiding wire breakage and dimensional deviations caused by die wear, tension fluctuations, parameter mismatches, or internal stress concentration, effectively reducing the scrap rate and significantly improving the yield, while ensuring the surface smoothness and high dimensional accuracy of the ultrafine tantalum microwire.

[0021] (3) In some preferred embodiments, the present invention employs a pre-processing step different from the prior art before the continuous drawing process of coarse wire: tantalum rods are made by electron beam melting and spin cutting, rolled by a rhombic hole system, and then subjected to vacuum heat treatment and NaCl-KCl mixed salt bath surface treatment.

[0022] Existing technologies mostly employ vacuum sintering to prepare tantalum rods. The electron beam melting method used in this invention can increase tantalum purity to over 99.99%, avoiding stress concentration and wire breakage caused by impurities. Existing technologies often use round-hole rolling, resulting in a single deformation path and easily leading to uneven texture and microstructure. The rhombohedral-hole rolling system used in this invention subjects the metal to multi-directional, alternating stress states during rolling, creating a complex deformation path. This facilitates grain breakage and recrystallization, resulting in a more uniform and fine internal microstructure of the tantalum rod. It also provides better welding and elimination of defects such as porosity and shrinkage in the cast microstructure, and helps eliminate material directionality, ensuring that the mechanical properties of the final product are consistent in all directions. This provides a high-quality, isotropic billet with a uniform microstructure for subsequent drawing.

[0023] Existing technologies mostly use acid pickling for surface treatment. The NaCl-KCl mixed salt bath surface treatment used in this invention can form a uniform oxide protective layer on the tantalum wire surface, improve lubrication conditions, and reduce frictional resistance and surface adhesion tendency during the drawing process.

[0024] The aforementioned pre-process synergy, which differs from existing technologies, provides high-purity, uniformly structured, isotropic, and surface-condition tantalum wire blanks for continuous coarse wire drawing, reducing the risk of wire breakage from the source and laying the foundation for the efficient and stable operation of the subsequent three-stage drawing process.

[0025] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from the description and drawings, which are particularly pointed out. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 The image shows a scanning electron microscope (SEM) image of 0.05 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 3 of this invention. Figure 2 Scanning electron microscope (SEM) image of 0.045 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 13 of the present invention; Figure 3 Scanning electron microscope (SEM) image of 0.03 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 17 of the present invention; Figure 4This is a scanning electron microscope (SEM) image of the surface of a tantalum filament without scratches or groove defects, as described in an embodiment of the present invention. Figure 5 This is a scanning electron microscope (SEM) image of the surface of a tantalum filament without scratches or groove defects, as described in an embodiment of the present invention. Figure 6 This is a scanning electron microscope (SEM) image of the surface of a tantalum filament with shallow trench defects as described in an embodiment of the present invention. Figure 7 The image shows 0.05 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Embodiment 1 of the present invention. Figure 8 Image of 0.045 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 11 of this invention; Figure 9 Image of 0.03 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 16 of the present invention; Figure 10 The image shows the weight of 0.05 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Embodiment 1 of the present invention. Figure 11 The image shows the weight of 0.045 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 11 of this invention. Figure 12 The image shows the weight of 0.03 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 16 of this invention. Figure 13 The scanning electron microscope (SEM) image of 0.05 mm tantalum metal microwires obtained by the preparation method of ultrafine tantalum metal microwires provided in Example 2 of the present invention (the surface has shallow grooves). Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0029] In their long-term research and practice on the preparation of tantalum metal microwires, the inventors of this invention discovered that existing technologies generally suffer from problems such as high wire breakage rate, low yield, and difficulty in controlling dimensional accuracy when preparing ultrafine tantalum metal microwires smaller than 0.10 mm, especially smaller than 0.05 mm. Through in-depth research, the inventors found that the main reason for these problems is: First, the material properties of tantalum metal make drawing its ultrafine wires extremely difficult. Tantalum metal has a high melting point, high brittleness at room temperature, and is easily oxidized at high temperatures. As the wire diameter continues to decrease, its absolute load-bearing capacity decreases sharply, and even minor process fluctuations can lead to wire breakage. Current technology lacks sufficient understanding of the deformation behavior of tantalum metal in its ultrafine state and has failed to design a dedicated drawing process for its material properties.

[0030] Secondly, existing drawing processes lack segmented designs for ultra-fine tantalum wires. Current technologies mostly employ continuous drawing methods, failing to rationally divide the process according to changes in wire diameter. This leads to unreasonable deformation distribution, excessively rapid accumulation of work hardening, and stress concentration, ultimately causing wire breakage. Furthermore, the control of drawing tension and linear speed after reaching a finer diameter is not precise enough; tension fluctuations or improper speed further exacerbate the risk of wire breakage and dimensional deviations.

[0031] Third, there is a lack of coordination and matching between mold selection and process parameters. Existing technologies mostly use molds and parameters for tantalum wires larger than 0.10mm (such as tungsten steel molds and larger single-pass processing rates), without selecting appropriate mold materials and optimizing key parameters such as deformation angle and sizing zone length for the characteristics of ultra-fine tantalum wires, resulting in surface adhesion, scratches and dimensional deviations.

[0032] Fourth, the preceding processes failed to provide high-quality blanks for subsequent drawing. Existing technologies mostly employ vacuum sintering to prepare tantalum rods, resulting in limited microstructure uniformity and purity; round-drilling is used, leading to a single deformation path and significant microstructure anisotropy; and acid pickling surface treatment makes it difficult to form a uniform lubricating protective layer. These factors increase the risk of wire breakage during subsequent drawing from the outset.

[0033] To address the aforementioned problems, the inventors have systematically optimized and controlled various aspects, including process segmentation, pass allocation, processing rate gradient control, mold segmentation selection, deformation angle and sizing zone length optimization, tension and speed synergistic matching, and improvement of preceding billet quality. This has resulted in a method for preparing ultrafine tantalum metal microwires, as detailed below: This invention provides a method for preparing ultrafine tantalum metal microwires, comprising: Continuous drawing process for coarse wire: Tantalum wire with a diameter of Φ2.0mm~Φ2.5mm is continuously drawn in N1 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter of the tantalum wire to Φ0.50mm~Φ0.65mm; wherein, the single-pass die processing rate X i The total number of passes, N1, is controlled between 12% and 20%, and i is a positive integer between 1 and N1 (i is any positive integer between 1 and N1). Intermediate drawing process: The tantalum wire, after the continuous drawing process of the coarse wire, is continuously drawn in N2 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter of the tantalum wire to Φ0.18mm~Φ0.30mm; where the single-pass die processing rate X j The total number of passes, N2, is 14 to 19, and j is a positive integer from 1 to N2 (j is any positive integer between 1 and N2). Precision micro-wire drawing process: The tantalum wire after the intermediate drawing process is continuously drawn in N3 passes using a non-slip wire drawing machine and diamond dies, so that the diameter of the tantalum wire is finally reduced to Φ0.025mm~Φ0.055mm; where the single-pass die processing rate X k Controlled within 8%~16%, mold deformation angle θ k The sizing zone length L is controlled within the range of 9° to 14°. k The drawing thickness is controlled between 10μm and 30μm, the drawing tension is controlled between 6N and 12N, the linear speed is controlled between 0.8m / s and 1.8m / s, the total number of passes N3 is 16 to 21, and k is a positive integer from 1 to N3 (k is taken from any positive integer between 1 and N3).

[0034] Specifically, in the continuous drawing process of the coarse wire, the starting diameter is Φ2.0mm~Φ2.5mm, and for example, the starting diameters are Φ2.0mm, Φ2.1mm, Φ2.2mm, Φ2.3mm, Φ2.4mm, and Φ2.5mm. The ending diameter is Φ0.50mm~Φ0.65mm, and for example, the ending diameters are Φ0.50mm, Φ0.52mm, Φ0.55mm, Φ0.57mm, Φ0.60mm, Φ0.62mm, and Φ0.65mm.

[0035] Specifically, in the continuous drawing process of the coarse wire, the single-pass die processing rate X i Controlled between 12% and 20%, for example, the single-pass mold processing rate X i The percentages are 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0036] Specifically, in the continuous drawing process of the coarse wire, the total number of passes N1 is 17 to 20. For example, the total number of passes N1 is 17, 18, 19, or 20.

[0037] Preferably, in the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from below Φ2.4mm to below Φ0.63mm, N1=17~20, and the single-pass die processing rate X for each pass is... i Control will be implemented in the following three stages: In the first stage, the number of passes a1 is 3~8, X i =18%~20%; In the second stage, the number of passes a2 is 4~10, X i =15%~17%; In the third stage, the number of passes a3 is 4~10, X i =12%~15%; And a1+a2+a3=N1.

[0038] It should be noted that, based on the deformation characteristics of tantalum metal during the coarse wire drawing stage, this invention divides all passes of continuous coarse wire drawing into three stages according to their sequence, and rationally allocates the number of passes and the single-pass processing rate for the three stages based on the work hardening law of tantalum metal. In the first stage, utilizing the good plasticity in the coarse state, a smaller number of passes combined with a higher single-pass processing rate are used to achieve rapid diameter reduction, fully leveraging the plastic potential of the coarse wire stage; in the second stage, as the wire becomes finer and the degree of work hardening increases, a larger number of passes combined with an appropriately reduced single-pass processing rate are used to fully release the deformation energy and control the rate of work hardening accumulation; in the third stage, the wire has been refined to a certain extent and the deformation resistance has increased, with the remaining number of passes combined with an even lower single-pass processing rate to complete the final diameter reduction, avoiding stress concentration that could lead to wire breakage. By using the three-stage, progressively decreasing processing rate and the reasonable ratio of the number of passes in each stage, the deformation amount in each pass is matched with the current diameter and hardening state of the wire, and the deformation energy is released evenly in each pass. This effectively reduces the rate of work hardening accumulation, avoids internal stress concentration, significantly reduces the risk of wire breakage, and ensures the continuous and stable operation of the drawing process.

[0039] More preferably, in the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.54mm~Φ0.63mm, N1 is 17~18, and the single-pass die processing rate X for each pass is... i Control will be implemented in the following three stages: In the first stage, the number of passes a1 is 3~6, ​​X i =18%~20%; In the second stage, the number of passes a2 is 6~7, X i =15%~17%; In the third stage, the number of passes a3 is 5-8, X i =12%~15%; And a1+a2+a3=N1.

[0040] In some preferred embodiments, during the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.59mm~Φ0.63mm, N1=17, and the single-pass die processing rate X for each pass is... i Control will be implemented in the following three stages: Phase 1, Courses 1-6, Xi =18%~20%, i=1~6; Phase Two, Courses 7-12, X i =16%~17%, i=7~12; Phase 3, Courses 13-17, X i =14%~15%, i=13~17.

[0041] In some preferred embodiments, during the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.54mm~Φ0.58mm, N1=18, and the single-pass die processing rate X for each pass is... i Control will be implemented in the following three stages: Phase 1, Courses 1-3, X i =18%~20%, i=1~3; Second stage, courses 4-10, X i =15%~16%, i=4~10; Phase 3, Courses 11-18, X i =12%~13%, i=11~18.

[0042] It should be noted that during the continuous drawing stage of coarse wire, the wire diameter is relatively large and the plasticity is good. However, as the number of passes increases, work hardening gradually accumulates and the deformation resistance continuously increases. Based on this deformation characteristic, this invention comprehensively considers factors such as rapid diameter reduction efficiency, work hardening rate control, suppression of internal stress accumulation, and blank matching for subsequent processes, and provides refined control schemes for the processing rate of each pass for the two pass schemes: For the first pass scheme (17 passes, final diameter Φ0.59mm~Φ0.63mm), this invention controls the single-pass die processing rate of passes 1-6 at 18%~20%, utilizing the good plasticity in the rough state for rapid diameter reduction; the single-pass die processing rate of passes 7-12 is controlled at 16%~17%, controlling the rate of work hardening accumulation; the single-pass die processing rate of passes 13-17 is controlled at 14%~15%, smoothly completing the final diameter reduction and avoiding internal stress concentration.

[0043] For the second pass scheme (18 passes, termination diameter Φ0.54mm~Φ0.58mm), this invention controls the single-pass die processing rate of the 1st to 3rd passes at 18%~20% for rapid diameter reduction; the single-pass die processing rate of the 4th to 10th passes at 15%~16%, allowing the deformation energy to be fully released through more intermediate passes; and the single-pass die processing rate of the 11th to 18th passes at 12%~13%, resulting in more uniform microstructure and a finer termination diameter.

[0044] The aforementioned refined control scheme matches the deformation amount in each pass with the current diameter and hardening state of the filament, effectively reducing the cumulative rate of work hardening and avoiding stress concentration, thus significantly reducing the risk of wire breakage. Simultaneously, the reasonable distribution of deformation ensures the consistency of the filament diameter and surface quality, improving dimensional accuracy and yield, and further enabling continuous, unbroken wire production at the kilometer level. In contrast, if the gradient segment division is unreasonable or the processing rate range is improperly set, it may lead to an imbalance in the distribution of deformation, causing excessively rapid work hardening, stress concentration, or fluctuations in the filament diameter, resulting in problems such as wire breakage and dimensional deviations, ultimately leading to a decrease in yield and making it difficult to meet the requirements for the preparation of ultrafine tantalum microfilaments.

[0045] Specifically, in the intermediate drawing process, the starting diameter is Φ0.50mm~Φ0.65mm (corresponding to the ending diameter of the continuous drawing process for coarse wire). For example, the starting diameters are Φ0.50mm, Φ0.52mm, Φ0.55mm, Φ0.57mm, Φ0.60mm, Φ0.62mm, and Φ0.65mm. The ending diameter is Φ0.18mm~Φ0.30mm. For example, the ending diameters are Φ0.18mm, Φ0.20mm, Φ0.22mm, Φ0.25mm, Φ0.27mm, Φ0.28mm, and Φ0.30mm.

[0046] Specifically, in the intermediate drawing process, the single-pass die processing rate X j Controlled at 10%~15%, for example, single-pass mold processing rate X j The percentages are 10%, 11%, 12%, 13%, 14%, and 15%.

[0047] Specifically, in the intermediate drawing process, the total number of passes N2 is 14 to 19. For example, the total number of passes N2 is 14, 15, 16, 17, 18, or 19.

[0048] Preferably, in the intermediate drawing process, when the tantalum wire diameter is drawn from below Φ0.63mm to below Φ0.27mm, N2 = 14~19, and the single-pass die processing rate X for each pass is... j Control will be implemented in the following three stages: In the first stage, the number of passes b1 is 3-8, X j =14%~15%; In the second stage, the number of passes b2 is 4~10, X j =12%~13%; In the third stage, the number of passes (b3) is 3-8, X j =10%~12%; And b1+b2+b3=N2.

[0049] It should be noted that in the intermediate drawing process, the diameter of the tantalum wire after continuous drawing from the coarse wire has been refined to a certain extent. At this point, the tantalum metal has undergone a certain degree of work hardening after the previous deformation, and its plasticity has decreased compared to the coarse wire stage, while its deformation resistance has further increased. If the processing rate is not properly allocated, work hardening will accumulate rapidly, and internal stress will increase sharply, which can easily lead to wire breakage in subsequent drawing processes. Based on the above deformation characteristics of the intermediate drawing stage, this invention divides all passes of the intermediate drawing process into three stages according to their sequence, and based on the law that the degree of work hardening of tantalum metal gradually increases with the number of passes, the number of passes and the processing rate per pass are reasonably allocated to the three stages. In the first stage, utilizing the remaining good plasticity of the wire, a smaller number of passes combined with a higher single-pass processing rate are used to stabilize the diameter reduction and achieve the initial release of deformation energy. In the second stage, as the wire diameter further decreases and the degree of work hardening continues to increase, a larger number of passes combined with a moderately reduced single-pass processing rate are used to fully release the deformation energy and effectively control the rate of work hardening accumulation. In the third stage, the wire has been refined to a certain extent and the deformation resistance has increased. The remaining number of passes combined with an even lower single-pass processing rate are used to complete the final diameter reduction, avoiding internal stress concentration and wire breakage. Through the gradient reduction of processing rates from high to low in the above three stages and the reasonable ratio of passes in each stage, the deformation amount in each pass is matched with the current diameter and hardening state of the wire, and the deformation energy is released evenly in each pass. This ensures the diameter reduction efficiency while effectively controlling the work hardening rate, avoiding internal stress concentration, further reducing the risk of wire breakage, and providing a blank foundation with uniform diameter and excellent microstructure for subsequent precision microfilament drawing processes.

[0050] More preferably, in the intermediate drawing process, when the tantalum wire diameter is drawn from Φ0.54mm~Φ0.63mm to Φ0.18mm~Φ0.27mm, N2=15~18, and the single-pass die processing rate X for each pass is... j Control will be implemented in the following three stages: In the first stage, the number of passes b1 is 5-6, X j =14%~15%; In the second stage, the number of passes b2 is 5~9, X j =12%~13%; In the third stage, the number of passes (b3) is 3-5, X j =10%~12%; And b1+b2+b3=N2.

[0051] In some preferred embodiments, during the intermediate drawing process, when the tantalum wire diameter is drawn from Φ0.59mm~Φ0.63mm to Φ0.23mm~Φ0.27mm, N2=15, and the single-pass die processing rate X for each pass is... j Control will be implemented in the following three stages: Phase 1, Courses 1-5, Xj =14%~15%, j=1~5; Second stage, courses 6-10, X j =12%~13%, j=6~10; Phase 3, Courses 11-15, X j =11%~12%, j=11~15.

[0052] In some preferred embodiments, during the intermediate drawing process, when the tantalum wire diameter is drawn from Φ0.54mm~Φ0.58mm to Φ0.18mm~Φ0.22mm, N2=18, and the single-pass die processing rate X for each pass is... j Control will be implemented in the following three stages: Phase 1, Courses 1-6, X j =14%~15%, j=1~6; Phase Two, Courses 7-15, X j =12%~13%, j=7~15; Phase 3, Courses 16-18, X j =10%~11%, j=16~18.

[0053] It should be noted that during the intermediate drawing stage, the wire diameter has been refined from a relatively coarse state (e.g., Φ0.50mm~Φ0.65mm) to an even finer state (e.g., Φ0.18mm~Φ0.30mm). At this point, the work hardening degree of tantalum metal is relatively high, the plasticity is lower than in the coarser drawing stage, and the deformation resistance is further increased. Based on this deformation characteristic of the intermediate drawing stage, this invention comprehensively considers factors such as the continuous release of deformation energy, further control of the work hardening rate, and providing uniformly structured blanks for subsequent precision micro-wire drawing processes. It provides refined control schemes for the processing rate of each pass for both intermediate drawing pass schemes.

[0054] For the first type of drawing pass scheme (total of 15 passes, drawing from Φ0.59mm~Φ0.63mm to Φ0.23mm~Φ0.27mm), this invention controls the single-pass die processing rate of passes 1-5 at 14%~15%, utilizing the remaining good plasticity of the wire to stabilize the diameter reduction; the single-pass die processing rate of passes 6-10 is controlled at 12%~13%, appropriately reducing the deformation to control the accumulation of work hardening; the single-pass die processing rate of passes 11-15 is controlled at 11%~12%, completing the final diameter reduction with a smaller deformation and avoiding internal stress concentration. This scheme has fewer passes, a smooth gradient transition, and balances production efficiency and drawing stability.

[0055] For the second type of drawing pass scheme (total of 18 passes, drawing from Φ0.54mm~Φ0.58mm to Φ0.18mm~Φ0.22mm), this invention controls the single-pass die processing rate of passes 1-6 at 14%~15% for stable diameter reduction; the single-pass die processing rate of passes 7-15 is controlled at 12%~13%, with up to 9 passes in this stage, allowing the deformation energy to be fully and uniformly released; the processing rate of passes 16-18 is controlled at 10%~11%, completing the final diameter reduction with a smaller deformation amount, resulting in a more uniform and finer filament structure and a finer final diameter. This scheme focuses more on product quality and structural uniformity, providing blanks with smaller diameters and better structural conditions for subsequent precision microfilament drawing processes.

[0056] The refined control scheme for the intermediate drawing stage described above matches the deformation amount in each pass with the current diameter and hardening state of the wire. This effectively controls the work hardening rate during the intermediate drawing process, avoids stress concentration, and further reduces the risk of wire breakage. Simultaneously, the reasonable distribution of deformation ensures the consistency of the wire diameter and surface quality after intermediate drawing, further improving dimensional accuracy and yield. This also better enables continuous, unbroken wire production at the kilometer level and provides a uniformly structured, appropriately sized blank for subsequent precision microwire drawing processes. In contrast, if the gradient segment division in the intermediate drawing stage is unreasonable or the processing rate range is improperly set, it may lead to an imbalance in deformation distribution, resulting in excessively rapid work hardening, stress concentration, or fluctuations in wire diameter. This can cause problems such as wire breakage and dimensional deviations, ultimately leading to a decrease in yield and making it difficult to meet the requirements for preparing ultrafine tantalum microwires.

[0057] Specifically, in the precision microfilament drawing process, the starting diameter is Φ0.18mm~Φ0.30mm (corresponding to the ending diameter of the intermediate drawing process). For example, the starting diameters are Φ0.18mm, Φ0.19mm, Φ0.20mm, Φ0.21mm, Φ0.22mm, Φ0.23mm, Φ0.24mm, Φ0.25mm, Φ0.26mm, Φ0.27mm, Φ0.28mm, Φ0.29mm, and Φ0.30mm. The termination diameter is Φ0.025mm~Φ0.055mm. For example, the termination diameter is Φ0.025mm, Φ0.028mm, Φ0.030mm, Φ0.032mm, Φ0.035mm, Φ0.038mm, Φ0.040mm, Φ0.042mm, Φ0.045mm, Φ0.048mm, Φ0.050mm, Φ0.053mm, or Φ0.055mm.

[0058] Specifically, in the precision micro-wire drawing process, the single-pass die processing rate X k Controlled between 8% and 16%, for example, the single-pass mold processing rate X kThe percentages are 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, and 16%.

[0059] Specifically, in the precision microfilament drawing process, the die deformation angle θ k Controlled within 9°~14°, for example, the mold deformation angle θ k The angles are 9°, 10°, 11°, 12°, 13°, and 14°.

[0060] Specifically, in the precision microfilament drawing process, the length L of the sizing zone... k The diameter is controlled within 10μm to 30μm. For example, the length L of the sizing zone is... k The sizes are 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, and 30μm.

[0061] Specifically, in the precision microfilament drawing process, the drawing tension is controlled between 6N and 12N. For example, the drawing tensions are 6N, 7N, 8N, 8.5N, 9N, 9.5N, 10N, 11N, and 12N.

[0062] Specifically, in the precision microfilament drawing process, the linear speed is controlled between 0.8 m / s and 1.8 m / s. For example, the linear speeds are 0.8 m / s, 0.9 m / s, 1.0 m / s, 1.1 m / s, 1.2 m / s, 1.3 m / s, 1.4 m / s, 1.5 m / s, 1.6 m / s, 1.7 m / s, and 1.8 m / s.

[0063] Specifically, in the precision microfilament drawing process, the total number of passes N3 is 16 to 21. For example, the total number of passes N3 is 16, 17, 18, 19, 20, or 21.

[0064] Preferably, in the precision microfilament drawing process, the drawing tension is controlled at 8~10N and the linear speed is controlled at 1.0~1.6m / s.

[0065] Preferably, in the precision micro-wire drawing process, when the tantalum wire diameter is drawn from below Φ0.27mm to below Φ0.052mm, N3 = 16~21, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: In the first stage, the number of rounds c1 is 2~12, X k =15%~16%, θ k =12°~14°, L k =10~14μm; In the second stage, the number of passes c2 is 4~8, X k=11%~14%, θ k =10°~12°, L k =15~19μm; In the third stage, the number of passes (c3) is 5-13, X k =8%~13%, θ k =9°~11°, L k =20~25μm; And c1+c2+c3=N3.

[0066] It should be noted that in the precision microwire drawing process, the tantalum wire diameter is already extremely fine. At this point, the tantalum metal has undergone significant work hardening and a marked decrease in plasticity after the two stages of coarse wire and intermediate drawing, resulting in a sharp reduction in absolute load-bearing capacity. Simultaneously, due to the extremely fine wire diameter, surface quality becomes particularly crucial to the final product performance—any minute surface scratches, adhesions, or grooves can lead to microwire breakage during subsequent use or processing. Based on these deformation characteristics of the precision microwire drawing stage, this invention divides all passes of the process into three stages in chronological order, and coordinates and controls the number of passes, single-pass processing rate, die deformation angle, and sizing zone length for each stage. In the first stage, the wire still has a certain degree of plasticity. A smaller number of passes, combined with a higher processing rate, a larger deformation angle, and a shorter sizing zone length, allows the wire to smoothly enter the deformation zone and establish good lubrication, achieving stable diameter reduction. In the second stage, as the wire becomes further refined and the degree of work hardening continues to increase, the number of passes is increased, while the processing rate is appropriately reduced, the deformation angle is decreased, and the sizing zone length is increased to control the work hardening rate and reduce friction, allowing the deformation energy to be fully released. In the third stage, the wire has been refined to near its final specification, with the highest degree of work hardening and the lowest plasticity. Therefore, the remaining number of passes, combined with the lowest processing rate, the smallest deformation angle, and the longest sizing zone length, ensures that the wire, in its extremely fine state, smoothly completes the final diameter reduction with minimal deformation, guaranteeing surface finish and dimensional accuracy. By employing the synergistic control strategy of decreasing processing rate, decreasing deformation angle, and increasing sizing zone length in the three stages mentioned above, the deformation amount of each pass is matched with the current diameter and hardening state of the wire, and the deformation energy is released uniformly in each pass. This effectively controls the work hardening rate, reduces friction and temperature rise, avoids surface adhesion and scratches, significantly reduces the risk of wire breakage, and ensures the surface smoothness, high dimensional accuracy, and high yield of ultrafine tantalum metal microwires.

[0067] More preferably, in the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.028mm~Φ0.052mm, N3=17~20, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: In the first stage, the number of rounds c1 is 2~10, X k =15%~16%, θ k =12°~14°, L k =10~13μm; In the second stage, the number of passes c2 is 4~5, X k =11%~14%, θ k =10°~12°, L k =15~18μm; In the third stage, the number of passes c3 is 5~11, X k =8%~13%, θ k =9°~11°, L k =20~25μm; And c1+c2+c3=N3.

[0068] In some preferred embodiments, during the precision microwire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.048mm~Φ0.052mm, N3=17, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-2, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~2; Second stage, courses 3-6, X k =13%~14%, θ k =10°~12°, L k =15~17μm, k=3~6; Phase 3, Courses 7-17, X k =12%~13%, θ k =9°~10°, L k =20~25μm, k=7~17.

[0069] In some preferred embodiments, during the precision microwire drawing process, when the tantalum wire diameter is drawn from Φ0.23mm~Φ0.27mm to Φ0.048mm~Φ0.052mm, N3=17, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-2, Xk =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~2; Second stage, courses 3-6, X k =13%~14%, θ k =10°~12°, L k =15~17μm, k=3~6; Phase 3, Courses 7-17, X k =12%~13%, θ k =9°~10°, L k =20~25μm, k=7~17.

[0070] In some preferred embodiments, during the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.043mm~Φ0.047mm, N3=18, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-5, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~5; Second stage, courses 6-10, X k =11%~12%, θ k =11°~12°, L k =15~18μm, k=6~10; Phase 3, Courses 11-18, X k =9%~10%, θ k =10°~11°, L k =20~23μm, k=11~18.

[0071] In some preferred embodiments, during the precision microwire drawing process, when the tantalum wire diameter is drawn from Φ0.23mm~Φ0.27mm to Φ0.043mm~Φ0.047mm, N3=18, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-5, X k =15%~16%, θ k =12°~14°, Lk =10~12μm, k=1~5; Second stage, courses 6-10, X k =11%~12%, θ k =11°~12°, L k =15~18μm, k=6~10; Phase 3, Courses 11-18, X k =9%~10%, θ k =10°~11°, L k =20~23μm, k=11~18.

[0072] In some preferred embodiments, during the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.028mm~Φ0.032mm, N3=20, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-10, X k =15%~16%, θ k =12°~13°, L k =10~13μm, k=1~10; Phase Two, Courses 11-15, X k =11%~12%, θ k =10°~12°, L k =15~18μm, k=11~15; Phase 3, Courses 16-20, X k =8%~9%, θ k =10°~11°, L k =20~23μm, k=16~20.

[0073] In some preferred embodiments, during the precision microwire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.22mm to Φ0.028mm~Φ0.032mm, N3=20, and the single-pass die processing rate X for each pass is... k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-10, X k =15%~16%, θ k =12°~13°, L k =10~13μm, k=1~10; Phase Two, Courses 11-15, X k =11%~12%, θ k =10°~12°, L k =15~18μm, k=11~15; Phase 3, Courses 16-20, X k =8%~9%, θ k =10°~11°, L k =20~23μm, k=16~20.

[0074] It should be noted that during the precision micro-wire drawing stage, the wire diameter has been further refined from a relatively fine state to an extremely fine state. At this point, the work hardening degree of tantalum metal is very high, its plasticity has decreased significantly, and its absolute load-bearing capacity has dropped sharply. Any improper setting of process parameters may lead to wire breakage. Based on this deformation characteristic of the precision drawing stage, this invention rationally divides the total number of passes into an initial stage, an intermediate stage, and a final stage for three different pass schemes, and performs fine control on the processing rate, deformation angle, and sizing zone length of each stage.

[0075] For the first precision drawing scheme (17 passes), this invention rationally divides the 17 passes into an initial stage (passes 1-2), an intermediate stage (passes 3-6), and a final stage (passes 7-17), and controls the machining rate, deformation angle, and sizing zone length in each stage. In the initial stage, a larger machining rate and deformation angle, and a shorter sizing zone length are used to smoothly establish lubrication and begin diameter reduction. In the intermediate stage, the machining rate is appropriately reduced, the deformation angle is decreased, and the sizing zone length is increased to control the work hardening rate and reduce friction. In the final stage, a smaller machining rate, a smaller deformation angle, and a longer sizing zone length are used to smoothly complete the final diameter reduction and ensure surface quality and dimensional accuracy.

[0076] For the second precision drawing scheme (18 passes), this invention rationally divides the 18 passes into an initial stage (passes 1-5), an intermediate stage (passes 6-10), and a final stage (passes 11-18), and controls the machining rate, deformation angle, and sizing zone length in each stage. This scheme results in a more uniform pass distribution across stages, a gentler machining rate gradient, and more complete release of deformation energy, making it particularly suitable for applications with higher requirements for diameter accuracy and surface quality.

[0077] For the third precision drawing scheme (20 passes), this invention rationally divides the 20 passes into an initial stage (passes 1-10), an intermediate stage (passes 11-15), and a final stage (passes 16-20), and controls the processing rate, deformation angle, and sizing zone length in each stage. This scheme has up to 10 passes in the initial stage, ensuring sufficient and uniform deformation of the wire in the coarser precision stage; the final stage uses the minimum processing rate, resulting in a more uniform and refined wire structure, superior surface quality, and higher diameter accuracy, making it suitable for applications with higher product quality requirements.

[0078] The refined control scheme of the aforementioned precision microwire drawing process matches the process parameters of each pass with the wire diameter and hardening state, effectively controlling the work-hardening rate, reducing friction and temperature rise, and avoiding surface adhesion and scratches, thereby significantly reducing the risk of wire breakage. Simultaneously, the reasonable parameter allocation ensures the consistency of wire diameter and surface finish, further improving dimensional accuracy and yield, and better realizing continuous, unbroken wire production at the kilometer level. In particular, the precise control of the precision microwire drawing stage directly determines the diameter accuracy, surface quality, and yield of the final product, and is the key to achieving high-quality preparation of ultrafine tantalum metal microwires in this invention.

[0079] The meanings of terms such as single-pass die processing rate, die deformation angle, and sizing zone length in this invention are consistent with their general meanings in the art. For example, in the field of wire drawing, single-pass die processing rate typically refers to the reduction in diameter of the wire after one drawing pass. ) and the diameter before the drawing of this pass percentage , where i represents the i-th pass (i=1, 2, 3...). The diameter after the (i-1)th drawing pass. The diameter after the i-th drawing pass is denoted by . The single-pass die processing rate is a core parameter for measuring the deformation amount in a single drawing pass. The die deformation angle usually refers to the deformation angle of the deformation zone (such as the cone part of the die hole) in the drawing die, and is a key angular parameter that determines the direction of metal flow and the uniformity of deformation. The sizing zone length usually refers to the length of the equal-diameter zone that the wire passes through after entering the die hole, and is used to stabilize the final size of the wire and extend the service life of the die.

[0080] Preferably, in the precision microfilament drawing process, each pass uses a consistent drawing tension and a consistent linear speed, with specific values ​​selected from their respective suitable ranges. For example, a fixed value (e.g., 8N, 9N, or 10N) is selected from the range of 8N to 10N, and this tension value is used for each pass; a fixed value (e.g., 1.0m / s, 1.1m / s, 1.2m / s, 1.3m / s, 1.4m / s, 1.5m / s, or 1.6m / s) is selected from the range of 1.0m / s to 1.6m / s, and this linear speed is used for each pass. This is because the wire diameter is already extremely fine in the precision microfilament drawing stage, and tension fluctuations or speed changes directly affect the wire diameter accuracy and increase the risk of wire breakage. Maintaining consistency and stability of tension and linear speed in each pass ensures that the wire passes through the die deformation zone of each pass in a constant state, avoiding diameter fluctuations and stress concentration caused by tension or speed changes. Meanwhile, the selected tension and speed values ​​are matched with parameters such as processing rate, deformation angle, and sizing zone length for each pass to ensure that the wire is in a better deformation and lubrication state in each pass, thereby reducing the risk of wire breakage while ensuring diameter consistency and surface quality.

[0081] Specifically, prior to the continuous drawing process of the coarse wire, the preparation method of the ultrafine tantalum metal microwire further includes: Tantalum rods are manufactured using electron beam melting and spin cutting. The tantalum bar is rolled using a rhombohedral die system; Vacuum heat treatment is performed after rolling; After vacuum heat treatment, the surface is treated with molten salt using a NaCl-KCl mixed salt bath.

[0082] In some embodiments, for tantalum rods produced by electron beam melting and spin cutting, the electron beam melting process purifies the material to over 99.99%. The vacuum degree of the electron beam melting process is 5 × 10⁻⁶. -5 ~5×10 -1 Pa, melting temperature is 1500~2000℃; the diameter of the tantalum rod produced by spinning is 20~30m (e.g., the length of the tantalum rod is 900mm).

[0083] It is understandable that electron beam melting increases the purity of tantalum to over 99.99%, effectively removing impurities such as oxygen, nitrogen, and carbon from tantalum. This avoids stress concentration and microcracks caused by impurities, providing a high-purity microstructure for subsequent drawing and reducing the risk of wire breakage from the outset. The spinning process produces tantalum rods with uniform microstructure and no internal cracks, ensuring consistent billet quality. The combined effect of these two processes provides pure, dense, and uniformly structured high-quality tantalum rod billets for subsequent rolling and drawing processes.

[0084] Optionally, the preparation of the tantalum billet used in the electron beam melting includes: selecting metallurgical grade tantalum powder, packaging and sealing it, and then performing cold isostatic pressing, with a pressing pressure of 80~200MPa and a holding time of 5~120 minutes; and performing pre-sintering treatment on the cold isostatically pressed billet, with a pre-sintering temperature of 900~1600℃ and a holding time of 0.25~2.5 hours.

[0085] Furthermore, the preparation of the tantalum billet used in the electron beam melting includes: selecting metallurgical grade tantalum powder, packaging and sealing it, and then performing cold isostatic pressing, with a pressing pressure of 100~180MPa and a holding time of 10~40 minutes; and performing pre-sintering treatment on the cold isostatically pressed billet, with a pre-sintering temperature of 1000~1500℃ and a holding time of 0.5~2 hours.

[0086] Preferably, the forming pressure of the cold isostatic pressing is 120~150MPa, and the holding time is 10~20 minutes; the temperature of the pre-sintering treatment is 1200~1400℃, and the holding time is 1~1.5 hours.

[0087] It is understandable that cold isostatic pressing (CIP) densifies tantalum powder under uniform pressure, resulting in a billet with uniform density and no segregation. Pre-sintering initially densifies the billet, increasing its strength and facilitating clamping and operation during subsequent electron beam melting. It also reduces the risk of deformation or cracking due to insufficient billet strength during electron beam melting. The synergistic effect of both processes provides a tantalum billet with uniform structure and suitable strength for electron beam melting, which is beneficial for ensuring the stability and purification effect of the melting process. By controlling appropriate CIP pressure, holding time, pre-sintering temperature, and holding time, optimal billet density and strength can be obtained. This ensures that the billet has sufficient density and strength to withstand the thermal stress and operational requirements during electron beam melting, while avoiding grain coarsening or impurity contamination due to over-sintering. This provides a high-quality tantalum billet with uniform structure and suitable strength for subsequent electron beam melting.

[0088] In some embodiments, the tantalum bar is rolled using a rhombic-square die system. The rolling passes are 16 to 20. The total deformation rate of the rolling process is 80 to 99%. Preferably, the total deformation rate is 85 to 95%. The rolling passes are 16 to 18. After rolling using the rhombic-square die system, the tantalum wire is rolled once or more using a circular die (or round die) to transition the cross-section of the tantalum wire from square / quasi-square to circular, for subsequent coarse wire drawing.

[0089] Understandably, compared to conventional round-pass rolling, this step offers the following advantages: the rhombic-square pass system subjects the metal to multi-directional, alternating stress states during rolling, resulting in a complex deformation path that facilitates grain breakage and recrystallization, leading to a more uniform and finer internal structure in the tantalum rod. Simultaneously, it provides better welding and elimination of defects such as porosity and shrinkage in the cast structure, and helps to eliminate material orientation, ensuring that the mechanical properties of the final product are consistent in all directions. By controlling the total deformation rate and number of passes during rolling, the tantalum rod achieves sufficient cumulative deformation while avoiding cracks or uneven microstructure caused by excessive deformation in a single pass, providing a high-quality billet with uniform microstructure and isotropic properties for subsequent drawing.

[0090] Optionally, vacuum heat treatment is performed after rolling; the vacuum degree of the vacuum heat treatment is 5×10⁻⁶. -3 ~5×10 -1 Pa, vacuum heat treatment temperature is 900~1600℃, and holding time is 0.25~2.5 hours.

[0091] In some embodiments, vacuum heat treatment is performed after rolling. The vacuum degree of the vacuum heat treatment is 5 × 10⁻⁶. -3 ~5×10 -1 Pa, vacuum heat treatment temperature is 1000~1500℃, and holding time is 0.5~2 hours.

[0092] Preferably, the vacuum degree of the vacuum heat treatment is 1×10⁻⁶. -5 ~5×10 -2 Pa, vacuum heat treatment temperature is 1100~1300℃, holding time is 0.5~1.5 hours.

[0093] It is understandable that vacuum heat treatment can eliminate residual internal stress generated during rolling, promote recrystallization, refine and homogenize grains, and prevent tantalum oxidation at high temperatures, thus providing a billet with stable microstructure and good stress state for subsequent drawing. By controlling the appropriate vacuum level, temperature, and holding time, better recrystallization microstructure and stress release effects can be obtained. This avoids insufficient recrystallization due to excessively low temperatures, and prevents grain coarsening due to excessively high temperatures or excessively long holding times, thereby ensuring that the billet has a uniform and fine microstructure and a stable stress state, providing a high-quality billet for subsequent drawing processes.

[0094] In existing technologies, the surface treatment of tantalum materials mainly adopts methods such as pickling, anodizing, or air-heated oxidation. Pickling is prone to over-corrosion or hydrogen embrittlement, anodizing is a complex process to control, and air-heated oxide films have poor uniformity and easily reduce the plasticity of the substrate due to oxygen absorption, making it difficult to form a uniform and dense oxide protective layer.

[0095] To address the aforementioned problems, this invention employs a molten salt treatment after vacuum heat treatment, using a NaCl-KCl mixed salt bath. The advantages of this step are: the NaCl-KCl mixed salt bath can form a uniform and dense oxide protective layer on the tantalum wire surface. This protective layer bonds well with the substrate, significantly improving lubrication between the tantalum wire and the die, reducing frictional resistance and surface adhesion during drawing, and preventing oxidation of the tantalum wire during subsequent drawing processes. Compared to conventional surface treatment methods, the oxide layer formed by molten salt treatment is more uniform and dense, providing superior lubrication and helping to reduce drawing stress and the risk of wire breakage.

[0096] Optionally, the mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (2~8):(1~5), the temperature of the salt bath for molten salt treatment is 500~1050℃, and the time for molten salt treatment is 1~30 minutes.

[0097] Specifically, the mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (3~7):(1~4), the temperature of the salt bath for molten salt treatment is 600~1000℃, and the time for molten salt treatment is 2~10 minutes.

[0098] Preferably, the mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (4~5):(2~3), the temperature of the salt bath for molten salt treatment is 700~900℃, and the time for molten salt treatment is 2~5 minutes.

[0099] By controlling the appropriate salt bath ratio, temperature, and processing time, a moderately thick, uniform, and dense oxide protective layer can be obtained, ensuring good lubrication while avoiding excessive oxide layer thickness that could lead to peeling or affect subsequent drawing.

[0100] Specifically, the surface molten salt treatment includes the following steps: (1) Salt bath preparation NaCl and KCl are mixed evenly in a certain proportion and heated to a molten state in a molten salt furnace. For example, the mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (3~7):(1~4).

[0101] (2) Salt bath heating The molten salt furnace is heated to a set temperature to completely melt the mixed salt and maintain a stable temperature. For example, the salt bath temperature is 600~1000℃.

[0102] (3) Tantalum wire immersion treatment The tantalum wire, after vacuum heat treatment, is immersed in a molten salt bath and held for a certain period of time to allow a uniform protective oxide layer to form on the surface of the tantalum wire. For example, the molten salt treatment time is 2 to 10 minutes.

[0103] (4) Remove and cool The treated tantalum wire was removed from the salt bath and allowed to cool naturally to room temperature, allowing the surface oxide protective layer to stabilize and solidify.

[0104] (5) Cleaning and drying The cooled tantalum wire is cleaned to remove any residual salt stains on the surface, and then dried for later use.

[0105] For example, after the precision microfilament drawing process, the method further includes: performing sinusoidal mechanical straightening to obtain tantalum metal microfilaments.

[0106] This invention provides an ultrafine tantalum metal microwire, which is prepared using the above-described method for preparing ultrafine tantalum metal microwire.

[0107] Optionally, the diameter of the ultrafine tantalum metal microwire is less than 0.10 mm, and more specifically less than 0.055 mm.

[0108] In some embodiments, the diameter of the ultrafine tantalum metal microwire is 0.020~0.055mm. For example, the diameter of the ultrafine tantalum metal microwire is 0.025mm, 0.03mm, 0.035mm, 0.04mm, 0.045mm, or 0.05mm.

[0109] In some embodiments, the tensile strength of the ultrafine tantalum metal microwire is 900~1400MPa, and exemplary tensile strengths are 930MPa, 960MPa, 980MPa, 1000MPa, 1050MPa, 1078MPa, 1100MPa, 1150MPa, 1200MPa, 1250MPa, 1270MPa, 1290MPa, 1320MPa, 1350MPa, and 1380MPa.

[0110] In some embodiments, the elongation of the ultrafine tantalum metal microwire is 3 to 7%, for example, 3%, 4%, 5%, 6%, and 7%.

[0111] In some embodiments, the diameter accuracy of the ultrafine tantalum metal microwire is ≤ ±0.006 mm (diameter fluctuation is controlled within ±0.006 mm). For example, the diameter accuracy is ≤ ±0.006 mm, ≤ ±0.005 mm, ≤ ±0.004 mm, or ≤ ±0.003 mm.

[0112] In some embodiments, the breakage rate per kilometer of the ultrafine tantalum metal microwire is 0.

[0113] In some embodiments, the yield of the ultrafine tantalum metal microwires is greater than 85%. The ultrafine tantalum metal microwires have excellent surface quality, with no scratches, no grooves, or only minor local scratches, but no grooves, or local shallow grooves.

[0114] Non-slip wire drawing machine: a precision metal wire drawing device. Its core feature is that there is no relative slippage between the wire and the drive wheel / drum, and stable drawing is achieved through independent drive and tension control.

[0115] Drawing: The wire passes through multiple drawing dies in sequence. Under the precise and synchronized traction of the drive wheels, the diameter is continuously reduced without slippage or twisting. This can achieve ultra-low tension, large surface area reduction, and high-speed stable drawing, and is suitable for processing difficult-to-process rare metal microwires.

[0116] Surface treatment: Before drawing, oxide scale and impurities are removed by mechanical descaling, pickling, polishing, etc. During drawing, special lubricating / cooling media (such as drawing oil, emulsion) are used to reduce die wear and wire scratches. After drawing, cleaning, passivation and annealing are performed to ensure that the tantalum microwire surface is clean, free of oxidation and has uniform mechanical properties.

[0117] Tantalum metal microwires are made from high-purity tantalum metal (Ta, purity usually ≥99.99%) as raw material, and are produced by non-slip wire drawing and precision drawing. The diameter is extremely fine (generally ≤0.1mm, and microwires are mostly 0.01mm~0.05mm).

[0118] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0119] Example 1: This embodiment provides a method for preparing ultrafine tantalum metal microwires, wherein the final diameter of the ultrafine tantalum metal microwires obtained by the method is Φ0.050 mm. Specifically, the preparation method includes the following steps: Pre-processing: (1) Tantalum rods are produced by electron beam melting and spin cutting: Capacitor-grade tantalum powder with a particle size of 4-7 μm was selected, packaged, sealed, and then cold isostatically pressed at a pressure of 150 MPa for 120 minutes. The cold-isostatically pressed billet was then pre-sintered at 1000℃ for 2 hours. The pre-sintered billet was then placed in an electron beam melting furnace under a vacuum of 5 × 10⁻⁶. -3 The tantalum is purified to over 99.99% by electron beam melting at a melting temperature of 1500℃ and then cut into tantalum rods with a diameter of 20mm.

[0120] (2) The tantalum bar is rolled using a rhombohedral die system: The tantalum rods were rolled using a rhombohedral die system in 20 passes.

[0121] (3) Vacuum heat treatment after rolling: The rolled tantalum wire was placed in a vacuum heat treatment furnace with a vacuum degree of 5×10⁻⁶. -3 Pa, vacuum heat treatment temperature is 1500℃, holding time is 2 hours, to eliminate stress.

[0122] (4) Surface molten salt treatment is performed after vacuum heat treatment: Mix NaCl and KCl at a mass ratio of 3:4 and heat them in a molten salt furnace to a molten state. The salt bath temperature is 500℃. Immerse the vacuum heat-treated tantalum wire in the molten salt bath for 30 minutes. Remove it and let it cool naturally to room temperature to allow the surface oxide protective layer to stabilize and solidify. Then clean the cooled tantalum wire to remove residual salt stains on the surface and dry it for later use.

[0123] Continuous drawing process for coarse wire: A tantalum wire with a pre-processed diameter of Φ2.0mm is drawn in 17 passes using a straight-feed wire drawing machine and tungsten carbide dies to reduce the diameter to Φ0.65mm; the single-pass die processing rate X i The percentages are as follows: Round 1 X1=20%, Round 2 X2=20%, Round 3 X3=19%, Round 4 X4=19%, Round 5 X5=18%, Round 6 X6=18%, Round 7 X7=17%, Round 8 X8=17%, Round 9 X9=17%, Round 10 X... 10 =16%, Course 11 X 11 =16%, Course 12 X 12 =16%, Course 13 X 13 =15%, Course 14 X 14 =15%, 15th round X 15 =15%, 16th round X 16 =14%, Course 17 X 17 =14%.

[0124] Intermediate drawing process: A tantalum wire with a diameter of Φ0.65mm after the continuous drawing process is then drawn in 15 passes using a direct-feed wire drawing machine and tungsten carbide dies to reduce the diameter to Φ0.30mm; the single-pass die processing rate X j The percentages are as follows: Round 1 X1=15%, Round 2 X2=15%, Round 3 X3=15%, Round 4 X4=14%, Round 5 X5=14%, Round 6 X6=13%, Round 7 X7=13%, Round 8 X8=13%, Round 9 X9=12%, Round 10 X... 10 =12%, Course 11 X 11 =12%, Course 12 X 12 =12%, Course 13 X 13=11%, Course 14 X 14 =11%, Course 15 X 15 =11%.

[0125] Precision microfilament drawing process: A tantalum wire with a diameter of Φ0.30mm after the intermediate drawing process is continuously drawn in 16 passes using a non-slip wire drawing machine and a diamond die (polycrystalline diamond) to reduce the diameter to Φ0.050mm. The single-pass die processing rate X k The percentages are as follows: Round 1 X1=16%, Round 2 X2=15%, Round 3 X3=14%, Round 4 X4=14%, Round 5 X5=13%, Round 6 X6=13%, Round 7 X7=13%, Round 8 X8=13%, Round 9 X9=13%, Round 10 X... 10 =13%, Course 11 X 11 =13%, Course 12 X 12 =13%, Course 13 X 13 =12%, 14th course X 14 =12%, Course 15 X 15 =12%, Course 16 X 16 =12%; Deformation angle θ of each pass mold k All are 9°; the length L of the sizing zone for each pass k All were 10μm; the drawing tension was controlled at 6N, and the linear speed was controlled at 0.8m / s.

[0126] Ultimately, ultrafine tantalum metal microwires with a diameter of Φ0.050mm were obtained.

[0127] Examples 2-17 are presented in list form. All other parameters not listed in each example are consistent with those in Example 1, specifically including: wire drawing equipment selection (the coarse wire continuous drawing process and the intermediate drawing process both use a direct-feed wire drawing machine with tungsten steel dies; the precision micro-wire drawing process uses a non-slip wire drawing machine with diamond dies). Common pre-treatment characteristics (electron beam melting purification to over 99.99%; rolling uses a rhombic die system, except in Example 17. After molten salt treatment, all are naturally cooled, cleaned to remove residual salt stains, and dried for later use). Common drawing process characteristics (each drawing pass is continuous, with no intermediate annealing).

[0128] Table 1-1 Process parameters of the embodiment (0.05mm tantalum microwire)

[0129] Table 1-2 Process parameters for the embodiments (0.045mm tantalum microwires)

[0130] Table 1-3 Process parameters for the examples (0.03mm microfilaments)

[0131] The parameters of Comparative Examples 1 to 5 are shown in Table 2, and the rest are basically the same as those of Example 1.

[0132] Table 2 Process parameters for the comparative example

[0133] Table 3 Performance test results of the embodiments

[0134] Based on the characteristics of the tantalum wire drawing process, the severity of surface defects can be classified into the following levels, as shown in Table 4, with the severity gradually increasing from level 1 to level 5.

[0135] Table 4: Classification of Surface Defects in Tantalum Wire

[0136] Table 3 shows that the test results indicate that the present invention achieves continuous and stable drawing of ultrafine tantalum metal microwires with a breakage rate of 0 per kilometer, and possesses excellent mechanical properties, high dimensional accuracy and good surface quality.

[0137] In this embodiment of the invention, the test results for the length of tantalum microwires are as follows: The gross weight of a 0.05 mm tantalum microwire is 0.827 kg, the coil weight is 0.020 kg, the net weight is 0.807 kg, and the equivalent length is approximately 24,000 m. The gross weight of a 0.045 mm tantalum microwire is 0.722 kg, the coil weight is 0.030 kg, the net weight is 0.692 kg, and the equivalent length is approximately 21,000 m. The gross weight of a 0.030 mm tantalum microwire is 0.286 kg, the coil weight is 0.080 kg, the net weight is 0.206 kg, and the equivalent length is approximately 14,000 m. This demonstrates that the preparation method provided in this embodiment of the invention can achieve continuous and stable drawing of tantalum microwires within the Φ0.025 mm to Φ0.055 mm specification range, with a breakage rate of 0 per kilometer. In Comparative Examples 1-5, due to deviations of one or more process parameters such as single-pass die processing rate, die deformation angle, sizing zone length, drawing tension, or linear speed during the roughing, intermediate, and finishing drawing stages from suitable ranges, frequent wire breakage occurred during the actual drawing process, making it impossible to achieve the stable production target of 0% wire breakage per kilometer. Because the drawing process cannot be carried out continuously and stably, the mechanical properties of the finished tantalum wire, such as tensile strength and elongation, fluctuate greatly, making it difficult to meet product standard requirements. Furthermore, the unstable drawing state before and after wire breakage further exacerbates surface scratches, grooves, and other defects, significantly deteriorating surface quality and making it difficult to meet the high-requirement requirements for tantalum wire surface integrity and quality in demanding application scenarios.

[0138] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing ultrafine tantalum metal microwires, characterized in that, include: Continuous drawing process for coarse wire: Tantalum wire with a diameter of Φ2.0mm~Φ2.5mm is continuously drawn in N1 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter to Φ0.50mm~Φ0.65mm; wherein, the single-pass die processing rate X i The percentage is controlled between 12% and 20%, the total number of passes N1 is 17 to 20, and i is a positive integer from 1 to N1; Intermediate drawing process: The tantalum wire, after the continuous drawing process of the coarse wire, is continuously drawn in N2 passes using a direct-feed wire drawing machine and tungsten carbide dies, reducing the diameter to Φ0.18mm~Φ0.30mm; where the single-pass die processing rate X j The percentage is controlled between 10% and 15%, the total number of passes N2 is 14 to 19, and j is a positive integer from 1 to N2; Precision micro-wire drawing process: The tantalum wire after the intermediate drawing process is continuously drawn in N3 passes using a non-slip wire drawing machine and diamond dies, reducing the diameter to Φ0.025mm~Φ0.055mm; where the single-pass die processing rate X k Controlled within 8%~16%, mold deformation angle θ k The sizing zone length L is controlled within the range of 9° to 14°. k The drawing diameter is controlled within 10μm to 30μm, the drawing tension is controlled within 6N to 12N, the linear speed is controlled within 0.8m / s to 1.8m / s, the total number of passes N3 is 16 to 21, and k is a positive integer from 1 to N3.

2. The method for preparing ultrafine tantalum metal microwires according to claim 1, characterized in that, In the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from below Φ2.4mm to below Φ0.63mm, N1=17~20, and the single-pass die processing rate X i Control will be implemented in the following three stages: In the first stage, the number of passes a1 is 3~8, X i =18%~20%; In the second stage, the number of passes a2 is 4~10, X i =15%~17%; In the third stage, the number of passes a3 is 4~10, X i =12%~15%; And a1+a2+a3=N1.

3. The method for preparing ultrafine tantalum metal microwires according to claim 1, characterized in that, In the aforementioned drawing process, when the tantalum wire diameter is drawn from below Φ0.63mm to below Φ0.27mm, N2 = 14~19, and the single-pass die processing rate X j Control will be implemented in the following three stages: In the first stage, the number of passes b1 is 3-8, X j =14%~15%; In the second stage, the number of passes b2 is 4~10, X j =12%~13%; In the third stage, the number of passes (b3) is 3-8, X j =10%~12%; And b1+b2+b3=N2.

4. The method for preparing ultrafine tantalum metal microwires according to claim 1, characterized in that, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from below Φ0.27mm to below Φ0.052mm, N3 = 16~21, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: In the first stage, the number of rounds c1 is 2~12, X k =15%~16%, θ k =12°~14°, L k =10~14μm; In the second stage, the number of passes c2 is 4~8, X k =11%~14%, θ k =10°~12°, L k =15~19μm; In the third stage, the number of passes (c3) is 5-13, X k =8%~13%, θ k =9°~11°, L k =20~25μm; And c1+c2+c3=N3.

5. The method for preparing ultrafine tantalum metal microwires according to claim 2, characterized in that, In the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.59mm~Φ0.63mm, N1=17, and the single-pass die processing rate X i Control will be implemented in the following three stages: Phase 1, Courses 1-6, X i =18%~20%, i=1~6; Phase Two, Courses 7-12, X i =16%~17%, i=7~12; Phase 3, Courses 13-17, X i =14%~15%, i=13~17; And / or, In the continuous drawing process of the coarse wire, when the diameter of the tantalum wire is drawn from Φ2.2mm~Φ2.4mm to Φ0.54mm~Φ0.58mm, N1=18, and the single-pass die processing rate X i Control will be implemented in the following three stages: Phase 1, Courses 1-3, X i =18%~20%, i=1~3; Second stage, courses 4-10, X i =15%~16%, i=4~10; Phase 3, Courses 11-18, X i =12%~13%, i=11~18.

6. The method for preparing ultrafine tantalum metal microwires according to claim 3, characterized in that, In the aforementioned drawing process, when the tantalum wire diameter is drawn from Φ0.59mm~Φ0.63mm to Φ0.23mm~Φ0.27mm, N2=15, and the single-pass die processing rate X j Control will be implemented in the following three stages: Phase 1, Courses 1-5, X j =14%~15%, j=1~5; Second stage, courses 6-10, X j =12%~13%, j=6~10; Phase 3, Courses 11-15, X j =11%~12%, j=11~15. And / or, In the aforementioned drawing process, when the tantalum wire diameter is drawn from Φ0.54mm~Φ0.58mm to Φ0.18mm~Φ0.22mm, N2=18, and the single-pass die processing rate X j Control will be implemented in the following three stages: Phase 1, Courses 1-6, X j =14%~15%, j=1~6; Phase Two, Courses 7-15, X j =12%~13%, j=7~15; Phase 3, Courses 16-18, X j =10%~11%, j=16~18.

7. The method for preparing ultrafine tantalum metal microwires according to claim 4, characterized in that, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.048mm~Φ0.052mm, N3=17, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-2, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~2; Second stage, courses 3-6, X k =13%~14%, θ k =10°~12°, L k =15~17μm, k=3~6; Phase 3, Courses 7-17, X k =12%~13%, θ k =9°~10°, L k =20~25μm, k=7~17; And / or, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.043mm~Φ0.047mm, N3=18, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-5, X k =15%~16%, θ k =12°~14°, L k =10~12μm, k=1~5; Second stage, courses 6-10, X k =11%~12%, θ k =11°~12°, L k =15~18μm, k=6~10; Phase 3, Courses 11-18, X k =9%~10%, θ k =10°~11°, L k =20~23μm, k=11~18; And / or, In the precision micro-wire drawing process, when the tantalum wire diameter is drawn from Φ0.18mm~Φ0.27mm to Φ0.028mm~Φ0.032mm, N3=20, and the single-pass die processing rate X k Mold deformation angle θ k and the length of the sizing zone L k Control will be implemented in the following three stages: Phase 1, Courses 1-10, X k =15%~16%, θ k =12°~13°, L k =10~13μm, k=1~10; Phase Two, Courses 11-15, X k =11%~12%, θ k =10°~12°, L k =15~18μm, k=11~15; Phase 3, Courses 16-20, X k =8%~9%, θ k =10°~11°, L k =20~23μm, k=16~20.

8. The method for preparing ultrafine tantalum metal microwires according to claim 1, characterized in that, Prior to the continuous drawing process of the coarse wire, the following is also included: Tantalum rods are manufactured using electron beam melting and spin cutting. The tantalum bar is rolled using a rhombohedral die system; Vacuum heat treatment is performed after rolling; After vacuum heat treatment, the surface is treated with molten salt using a NaCl-KCl mixed salt bath.

9. The method for preparing ultrafine tantalum metal microwires according to claim 8, characterized in that, The mass ratio of NaCl to KCl in the NaCl-KCl mixed salt bath is (3~7):(1~4). And / or, the salt bath temperature for the molten salt treatment is 600~1000℃; And / or, the molten salt treatment time is 2 to 10 minutes.

10. An ultrafine tantalum metal microwire, characterized in that, The ultrafine tantalum metal microwires were prepared using any one of claims 1 to 9.

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