Tungsten alloy wire, method for manufacturing the same and use thereof

Abstract

The application relates to the technical field of tungsten alloy materials, in particular to a tungsten alloy wire and a preparation method and application thereof. The tungsten alloy is composed of the following elements in mass fraction: L 0.4-1.1 wt%, X 0.001-0.01 wt%, Z 0.001-0.25 wt%, and the balance is tungsten and inevitable impurities; wherein the L is one or more than two of lanthanum, cerium, praseodymium, neodymium, gadolinium and erbium; the X is one or more than two of lutetium, europium, ytterbium, dysprosium, holmium, terbium and samarium; the Z includes oxygen; the wire diameter of the wire is 20-60 mu m; in the wire, there is linear L or a compound of the L along the wire shaft direction, and the radial average width D of the L or the compound of the L is less than or equal to 5 nm. According to the application, the linear L element is doped between the tungsten matrix, and the radial average width of the L is controlled to be less than or equal to 5 nm, so that the wire diameter of the wire can be 20-60 mu m, the tensile strength of the wire can be more than 5000 MPa under the wire diameter of 60 mu m, and the processing performance of the tungsten alloy wire is enhanced.

Description

[0001] This application claims priority to the Chinese patent application No. 2023118259397, filed on December 26, 2023, and entitled "A tungsten alloy wire and a preparation method and application thereof", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of tungsten alloy materials, in particular to a tungsten alloy wire and a preparation method and application thereof. BACKGROUND

[0003] Tungsten-based alloy is an alloy material made of refractory metal tungsten as hard phase, nickel, iron, copper or silver metal as binder phase, through powder metallurgy or injection molding technology. Due to its excellent thermal, mechanical, electrical and chemical properties, it is widely used in the fields of automobile, medical, aerospace, military and national defense.

[0004] In order to further improve the comprehensive mechanical properties of tungsten alloy wire, the existing technology dopes rare earth elements or rare earth compounds as the second phase dispersion strengthening tungsten material in the tungsten matrix. During high-temperature sintering and recrystallization annealing process, solid-liquid phase transformation occurs, and many second phase particles will merge and grow during the transformation process. In the current pressure processing process, uneven deformation caused by forging or drawing will lead to the fracture of the second phase particles, which cannot effectively improve the strength of the tungsten matrix. The combination of the second phase particles and the tungsten wire will form many cracks, causing wire breakage, and also limiting the diameter size of the deep processing of tungsten wire.

[0005] For example, the patent document CN113186438A discloses an alloy wire and a preparation method and application thereof, which contains lanthanum oxide with a content of 0.1wt%-2.0wt%, and the tensile strength of the alloy wire can reach 4800MPa at a diameter of 40μm or less. However, due to the large amount of rare earth oxide added, the defects of the wire increase sharply, the proportion of wire breakage failure in the preparation process increases significantly, and the deformation resistance of the alloy wire caused by the aggregation of the second phase of rare earth is too large, which leads to the decrease of the strength increment of the wire after thinning and the deterioration of the processing performance, thereby failing to meet the engineering requirements. SUMMARY

[0006] To solve the problem of many cracks and wire breakage caused by the introduction of the second phase in the existing technology, the present application provides a tungsten alloy wire, which is composed of the following mass fractions of elements: L 0.4-1.1wt%, X 0.001-0.01wt%, Z 0.001-0.25wt%, and the balance is tungsten and unavoidable impurities.

[0007] Wherein, the L is one or more than two of lanthanum, cerium, praseodymium, neodymium, gadolinium, erbium; the X is one or more than two of lutetium, europium, ytterbium, dysprosium, holmium, terbium, samarium; the Z includes oxygen; the wire diameter of the wire is 20-60μm, and in the wire, there is wire-shaped L or compound of L along the wire axis direction, and the radial average width D of the L or compound of L is ≤5nm.

[0008] For example, L represents lanthanum, or cerium, or praseodymium, or lanthanum and cerium, or lanthanum and neodymium, or lanthanum and praseodymium, or lanthanum and gadolinium, or cerium and praseodymium, or cerium and neodymium, or praseodymium and gadolinium, or praseodymium and erbium, or neodymium and gadolinium, or lanthanum, cerium and praseodymium, or lanthanum, cerium and erbium, or lanthanum, praseodymium and neodymium, or cerium, praseodymium and neodymium, or praseodymium, neodymium, gadolinium and erbium, etc.

[0009] For another example, the mass percentage of L is 0.4%-1.1%, or 0.4%-1.0%, or 0.4%-0.8%, or 0.4%-0.6%, or 0.4%-0.5%, or 1.0-1.1%, or 0.8%-1.1%, of course, it can also be 0.4%, 0.41%, 0.5%, 0.55%, 0.6%, 0.8%, 0.86%, 1.0%, 1.05%, etc.

[0010] The mass percentage of X is 0.001-0.01%, or 0.001-0.005%, of course, it can also be 0.001%, 0.005%, 0.006%, 0.008%, 0.009%, 0.0099%, etc.

[0011] The mass percentage of Z is 0.001%-0.25%, or 0.001%-0.05%, or 0.001%-0.1%, or 0.001%-0.2%, or 0.005%-0.1%, or 0.1%-0.25%, or 0.1%-0.2%, or 0.05%-0.2%, of course, it can also be 0.0009%, 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, etc.

[0012] The wire diameter of the wire is 20-60μm, for example, 20μm, 28μm, 30μm, 38μm, 40μm, 48μm, 50μm, 55μm, 58μm, 60μm, etc., the tungsten alloy wire can be uniform, or not completely uniform, and can also contain a few percentage points such as 1% according to the position;

[0013] It should be noted that "wire-shaped" means that the size of L or compound of L along the wire axis direction in the wire is much larger than the size along the radial direction of the wire.

[0014] The compound of L and the compound of X can be an oxide, such as lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, gadolinium oxide, erbium oxide, lutetium oxide, europium oxide, ytterbium oxide, dysprosium oxide, holmium oxide, terbium oxide, samarium oxide, etc. Of course, it can also be other forms of compounds, such as the carbide of L, the carbide of X.

[0015] In some embodiments, the Z further comprises one or more of carbon, boron, and nitrogen; when carbon, boron, and nitrogen are present simultaneously, the total amount of carbon, boron, and nitrogen is not more than 0.07%.

[0016] In some embodiments, the wire has a radial average width of tungsten grains ≤80nm.

[0017] Preferably, the wire has a ratio of the number of L or the compound of L to the number of tungsten grains γ, 3≤γ≤10.

[0018] Preferably, the wire has a surface defect number ≤10 per hundred meters.

[0019] Preferably, the wire has a dislocation density ≥5*10 9 / mm 2 .

[0020] To ensure the final strength of the obtained tungsten alloy wire product, the wire needs to have good comprehensive mechanical properties and good processing feasibility. Therefore, the ratio γ of the number of L or the compound of L to the number of tungsten grains in the wire is between 3 and 10. If γ<3, the breaking force of the wire cannot be met. If γ>10, the processing performance of the wire will deteriorate sharply, resulting in a sharp increase in cracks in the wire and serious wire breakage.

[0021] Preferably, when the wire diameter of the wire is >50μm and ≤60μm, the radial average width D of L or the compound of L is ≤5nm, and the tensile strength of the wire is ≥5000MPa; when the wire diameter of the wire is >40μm and ≤50μm, the radial average width D of L or the compound of L is ≤4nm, and the tensile strength of the wire is ≥5500MPa.

[0022] When the wire diameter of the wire is >30μm and ≤40μm, the radial average width D of L or the compound of L is ≤3nm, and the tensile strength of the wire is ≥6000MPa; when the wire diameter of the wire is ≥20μm and ≤30μm, the radial average width D of L or the compound of L is ≤2nm, and the tensile strength of the wire is ≥7000MPa.

[0023] The application also provides a preparation method of the tungsten alloy wire described above, which comprises wet doping, powdering, pressing, sintering, blooming, and pressure processing.

[0024] In some embodiments, the wet doping process is: uniformly dispersing blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly dispersing nano-sized compound powders of L and X in an alkaline solution with pH>11 to form a second suspension, and then spraying a solution containing Z element and the second suspension into the blue tungsten suspension, and obtaining the doped blue tungsten powder after drying.

[0025] Preferably, after uniformly dispersing the nano-sized compound powders of L and X in the alkaline solution with pH>11, high-speed stirring is performed by a stirring device with a speed of 1000-2000 r / min.

[0026] Preferably, the solution containing Z element is a salt solution of Z element or a suspension of a compound containing Z element.

[0027] Preferably, the solution of Z element is diluted to a volume ratio of 1:20 or more.

[0028] Preferably, the drying method is rapid vacuum heating drying.

[0029] By preparing a suspension of compounds of L and X elements, fine particles are directly and uniformly doped into blue tungsten powder, and the fine particles are used as heterogeneous nuclei to co-crystallize with tungsten particles. The tungsten alloy powder prepared by this method has more uniform dispersion. This method does not need to use acid salts of elements, has a wider selection range of dispersed particles, and can obtain tungsten materials with more stable and reliable performance.

[0030] In some embodiments, the preparation method of the blue tungsten powder is: feeding ammonium paratungstate into a reduction furnace, and reducing the ammonium paratungstate at 400-600°C under the protection of hydrogen and nitrogen to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer is less than 10 mm, the hydrogen flow in the reduction furnace is 20-40 L / min, the nitrogen flow is 80-160 L / min, the oxygen index of the blue tungsten powder is 2.85±0.05, and the ammonium tungsten bronze phase content is more than 80%.

[0031] The blue tungsten powder is prepared by using a hydrogen-nitrogen mixed gas as a reduction protection medium, and the performance of the discharged blue tungsten powder is controlled by the thickness of the material layer, the size and flow direction of hydrogen. The oxygen index of the blue tungsten is 2.85±0.05, and the proportion of the ammonium tungsten bronze phase in the blue tungsten is more than 80%. The blue tungsten particles are coarse and have many surface cracks, which is beneficial to the entry of the rare earth solution and improves the doping effectiveness, so as to improve the uniformity of the second phase in the tungsten wire and improve the comprehensive mechanical properties and processing performance of the tungsten wire.

[0032] In some embodiments, the powder preparation process is: reducing the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5-2.6 μm and alloy powder B with a particle size of 3.8-4.5 μm, and then uniformly mixing the alloy powder A and the alloy powder B to obtain a mixed powder.

[0033] The preferred reduction method for alloy powder A is as follows: the doped blue tungsten powder is reduced once in a hydrogen reduction furnace at 500-800°C, and then reduced a second time in a hydrogen reduction furnace at 700-1000°C to obtain alloy powder A with a particle size of 1.5-2.6 μm.

[0034] The preferred method for reducing the alloy powder B is as follows: reducing the doped blue tungsten powder in a hydrogen reduction furnace at 700-1100°C to obtain alloy powder B with a particle size of 3.8-4.5 μm.

[0035] Preferably, alloy powder A and alloy powder B are mixed at a mass ratio of 1:(1-2).

[0036] By mixing fine-grained tungsten alloy powder prepared by two reduction processes with coarse-grained tungsten alloy powder prepared by one high-temperature reduction process, the uneven local doping of coarse-grained powder during the reduction process is avoided, and the agglomeration and enrichment of fine-grained powder after reduction is effectively suppressed. This prevents microscopic uneven doping of alloy powder in subsequent pressure processing, thus reducing the risk of wire breakage.

[0037] In some embodiments, the sintering process is as follows: the pre-sintered billet obtained by pressing is subjected to electric current sintering, which is carried out in two stages. The first sintering is carried out at 60% of the tungsten bar melting current for 30-45 minutes, followed by cooling. The second sintering is carried out at 90%-92% of the tungsten bar melting current for 40-80 minutes, resulting in a density of 18.6 g / cm³. 3 The above are sintered billets.

[0038] The second sintering is preferably carried out in a hydrogen atmosphere, wherein the hydrogen purity is >99.5%.

[0039] This method employs a two-stage, segmented high-temperature sintering process, which differs from traditional single-stage high-temperature sintering and combined sintering with medium-frequency indirect sintering. Conventional single-stage sintering and combined sintering with medium-frequency indirect sintering only achieve billet densities of 17.2–18.4 g / cm³. 3 The tungsten wire has a density generally below 92% of its theoretical density, and its microstructure exhibits significant differences in uniformity between the core and edges, resulting in poor tungsten fiber size consistency. This leads to uneven microstructure during subsequent tungsten alloy material processing, making the wire prone to breakage. This application addresses this issue by using a first-stage electro-sintering process to fully volatilize impurities in the tungsten billet and close surface voids. A second-stage high-temperature electro-sintering process increases hydrogen purity and improves billet density, resulting in a uniform billet with a density exceeding 96%. This improves the uniformity of the billet microstructure, enhances the fiber consistency of the subsequent tungsten alloy wire, and improves the winding performance of the tungsten alloy wire.

[0040] In some embodiments, the pressure processing process is as follows: the alloy rod obtained from the billet is recrystallized and annealed, and then forged into a tungsten rod with a diameter of 2.5 to 4.0 mm by a multi-pass continuous rotary forging equipment. The tungsten rod is then rough drawn through drawing dies of different specifications, and the drawing passes are repeated multiple times with a compression ratio of 35% to 60% to obtain tungsten alloy coarse wire with a diameter of 0.3 to 0.5 mm.

[0041] Using a high compression ratio of 35% to 60% to process tungsten alloy wire results in more developed wire fibers, which facilitates the linearization of tungsten elements and their compounds during processing, thereby improving the breaking strength of the wire.

[0042] In some embodiments, during the pressure processing, the alloy rod obtained from the blanking is heated to 2000-2600°C by a medium / high frequency induction coil for recrystallization annealing.

[0043] In some embodiments, the tungsten alloy wire needs to be annealed when drawn to a diameter of 0.3–0.5 mm at an annealing temperature of 1300–1800 °C. After annealing, the tungsten alloy wire is cooled in an oxygen environment. The annealing process is repeated multiple times to obtain tungsten alloy wires of different diameters. When the tungsten alloy wire is drawn to a diameter below 0.3 mm, annealing is no longer performed. The annealed and cooled wire is then drawn using dies of different specifications, with repeated drawing processes to achieve the desired wire diameter.

[0044] By subjecting the wire to annealing followed by oxygen cooling treatment, the content and thickness of the oxide layer on the surface of the tungsten alloy wire can be increased, which can effectively improve the wire lubrication layer, thereby improving the drawing conditions, ensuring the feasibility of high compression ratio drawing of the wire, and thus significantly reducing the probability of wire breakage.

[0045] This application also provides an application of the above-mentioned tungsten alloy wire in the fields of cutting, cut-resistant protection, cables, screen printing, ropes, or textiles.

[0046] Compared with the prior art, the tungsten alloy wire provided in this application has the following advantages:

[0047] This application uses one or more rare earth elements / rare earth compounds as the second phase to strengthen tungsten materials. By controlling the L element to be linearly doped between the tungsten matrix and making the radial average width of L less than 5nm, the cracks and wire breaks caused by the second phase particles during subsequent pressure processing are greatly reduced. This helps to ensure the mechanical strength of the tungsten alloy wire, allowing the wire diameter to be 20-60μm. At a wire diameter of 60μm, it can have a tensile strength of more than 5000MPa, while also enhancing the processing performance of the tungsten alloy wire. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A schematic diagram of the radial average width measurement of the L or L compound provided in this application. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] This application provides a tungsten alloy wire, wherein the tungsten alloy is composed of the following elements by mass fraction:

[0052] L 0.4~1.1wt%, X 0.001~0.01wt%, Z 0.001~0.25wt%, balance being tungsten and unavoidable impurities;

[0053] Wherein, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; and X is one or more of lutetium, europium, ytterbium, dysprosium, holmium, terbium, and samarium.

[0054] Z includes oxygen;

[0055] The wire has a diameter of 20–60 μm, and the wire contains linear L-shaped or L-shaped compounds along the axial direction, with the radial average width D of the L-shaped or L-shaped compounds being ≤5 nm.

[0056] It is understandable that impurities are unavoidable, consisting of other elements introduced during the preparation process.

[0057] The radial average width of tungsten grains is ≤80nm;

[0058] The number of L or L compounds in the wire / the number of tungsten grains = γ, 3≤γ≤10;

[0059] When the wire diameter is >50μm and ≤60μm, the radial average width D of L or L compound is ≤5nm, and the tensile strength of the wire is ≥5000MPa.

[0060] When the wire diameter is >40μm and ≤50μm, the radial average width D of L or L compound is ≤4nm, and the tensile strength of the wire is ≥5500MPa.

[0061] When the wire diameter is >30μm and ≤40μm, the radial average width D of L or L compound is ≤3nm, and the tensile strength of the wire is ≥6000MPa.

[0062] When the wire diameter is ≥20μm and ≤30μm, the radial average width D of L or L compound is ≤2nm, and the tensile strength of the wire is ≥7000MPa.

[0063] The number of surface defects in the wire is ≤10 per 100 meters;

[0064] The dislocation density in the wire is ≥5*10 9 / mm 2 .

[0065] This application provides a method for preparing tungsten alloy wire, including wet doping, powder preparation, pressing, sintering, billet preparation, and pressure processing.

[0066] The wet doping process is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension; nano-sized compound powders of L and X are uniformly dispersed in an alkaline solution with pH > 11 to form a second suspension; then, the solution containing element Z and the second suspension are sprayed sequentially into the blue tungsten suspension; after spraying, rapid vacuum heating and drying are performed to obtain doped blue tungsten powder.

[0067] The preparation method of the blue tungsten powder is as follows: ammonium paratungstate is fed into a reduction furnace and reduced at 400-600℃ under the protection of hydrogen and nitrogen to obtain blue tungsten powder. The thickness of the ammonium paratungstate powder layer is <10mm. The hydrogen flow rate in the reduction furnace is 20-40L / min, the nitrogen flow rate is 80-160L / min, the oxygen index of the blue tungsten powder is 2.85±0.05, and the ammonium tungsten bronze phase composition is >80%.

[0068] The powder preparation process involves reducing the doped blue tungsten powder once in a hydrogen reduction furnace at 500–800°C, followed by a second reduction in a hydrogen reduction furnace at 700–1000°C, to obtain alloy powder A with a particle size of 1.5–2.6 μm.

[0069] The doped blue tungsten powder was reduced in a hydrogen reduction furnace at 700–1100°C to obtain alloy powder B with a particle size of 3.8–4.5 μm;

[0070] Alloy powder A and alloy powder B are mixed at a mass ratio of 1:(1~2) to obtain a mixed powder;

[0071] The sintering process involves subjecting the pre-sintered billet obtained by pressing to an electric current for sintering. The sintering is performed in two stages: the first sintering is conducted at 60% of the tungsten bar melting current for 30–45 minutes, followed by cooling; the second sintering is conducted at 90%–92% of the tungsten bar melting current for 40–80 minutes, yielding a density of 18.6 g / cm³. 3 The above sintered billets;

[0072] Preferably, the second sintering is carried out in a hydrogen atmosphere, wherein the hydrogen purity is >99.5%;

[0073] The pressure processing is as follows: the alloy rod obtained from the billet is heated to 2000-2600℃ by medium / high frequency induction coil for recrystallization annealing, and then forged into a tungsten rod with a diameter of 2.5-4.0mm by multi-pass continuous rotary forging equipment;

[0074] The tungsten rod is rough drawn through drawing dies of different specifications, and the drawing process is repeated multiple times with a compression ratio of 35% to 60% to obtain tungsten alloy coarse wire with a diameter of 0.3 to 0.5 mm.

[0075] The tungsten alloy wire needs to be annealed when it is drawn to a diameter of 0.3-0.5 mm at an annealing temperature of 1300-1800℃. After annealing, the tungsten alloy wire is cooled in an oxygen environment.

[0076] After annealing and cooling, the wire is drawn through drawing dies of different specifications, and the drawing process is repeated multiple times to draw the wire to the required diameter.

[0077] Furthermore, the pressing and blanking steps described above are preferably, but not limited to, the following implementation methods:

[0078] Pressing: The mixed powder is pressed into compacts weighing 1.5-6 kg by isostatic pressing at 140-240 MPa, and the compacts are pre-sintered at 1200-1400℃ for 10-30 minutes in a hydrogen atmosphere to increase the strength of the compacts.

[0079] Billet preparation: Using a multi-roll mill at 1600-1700℃, sintered billets with a diameter of 15-25mm are continuously rolled into alloy rods with a diameter of 8.0-12.0mm.

[0080] The preparation method also includes an electrolytic cleaning post-treatment step to facilitate subsequent electroplating operations.

[0081] Therefore, this application provides the elemental composition of tungsten alloys in the embodiments and comparative examples shown in Table 1 below:

[0082] Table 1 (Unit: wt%)

[0083]

[0084] The "-" indicates that the corresponding element has not been added.

[0085] Example 1.1

[0086] This embodiment is a tungsten alloy wire prepared according to this application, the material element composition of which includes: 0.55wt% gadolinium, 0.55wt% praseodymium, 0.01wt% lutetium, 0.03% carbon, 0.18wt% oxygen, and the balance being tungsten and unavoidable impurities;

[0087] The preparation steps are as follows:

[0088] Step 1: Preparation of Blue Tungsten: Ammonium paratungstate powder was subjected to hydrogen reduction in a reverse hydrogen continuous reduction furnace at 400℃, 450℃, 500℃, and 560℃. The thickness of the ammonium paratungstate powder layer was 6mm, the hydrogen flow rate was 40L / min, and the nitrogen flow rate was 80L / min, resulting in blue tungsten powder with an oxygen index of 2.8 and an ammonium tungsten bronze phase composition of 82%.

[0089] Step 2, wet doping: The blue tungsten powder obtained in Step 1 is uniformly dispersed in deionized water to obtain a blue tungsten suspension, wherein the volume ratio of blue tungsten powder to deionized water is 1:15; an appropriate amount of carbon powder and deionized water are mixed at a volume ratio of 1:20 to obtain a first suspension; an appropriate amount of nano-sized compound powders of gadolinium oxide, praseodymium oxide and lutetium oxide are uniformly dispersed in a sodium hydroxide solution with a pH of 12, and stirred at 1000 r / min in a high-speed emulsification device to form a second suspension; then the first suspension and the second suspension are sprayed sequentially into the blue tungsten suspension through a vacuum pipe; after spraying, rapid vacuum heating and drying are performed to obtain doped blue tungsten powder;

[0090] Step 3, Powder preparation: The doped blue tungsten powder obtained in step 2 is reduced once in a three-temperature zone hydrogen reduction furnace at 500℃, 650℃, and 750℃, and then reduced twice in a four-temperature zone hydrogen reduction furnace at 700℃, 810℃, 870℃, and 920℃ to obtain alloy powder A with a particle size of 2.6μm.

[0091] The doped blue tungsten powder obtained in step 2 was reduced in a four-temperature zone hydrogen reduction furnace at 720℃, 820℃, 870℃ and 950℃ to obtain alloy powder B with a particle size of 3.8μm.

[0092] Alloy powder A and alloy powder B are placed in a high-energy powder mixer at a ratio of 1:2 and mixed for 100 minutes to obtain a mixed powder.

[0093] Step 4, pressing: The mixed powder obtained in step 3 is pressed into a compact weighing 3 kg by isostatic pressing at 160 MPa, and the compact is pre-sintered at 1300℃ in a hydrogen atmosphere for 20 minutes to obtain a pre-sintered billet.

[0094] Step 5, Sintering: The pre-sintered billet obtained in Step 4 is subjected to electric current sintering. The sintering is carried out in two stages. The first sintering is performed at 60% of the tungsten bar melting current for 30 minutes, followed by cooling, purging and drying of the sintering shroud. The second sintering is performed at 90% of the tungsten bar melting current for 40 minutes, yielding a density of 18.68 g / cm³. 3 sintered billets;

[0095] Step 6, Billeting: Using a multi-roll mill at a heating temperature of 1600℃, the sintered billet with a diameter of 20mm is continuously rolled into an alloy rod with a diameter of 8.0mm.

[0096] Step 7, Pressure processing: The alloy rod obtained in step 6 is heated to 2000℃ by medium frequency induction coil for recrystallization annealing, and then forged into a tungsten rod with a diameter of 2.5mm by multi-pass continuous rotary forging equipment;

[0097] Step 8: The tungsten rod is rough drawn through drawing dies of different specifications. The drawing process is repeated multiple times with a compression ratio of 35% to 60% to obtain tungsten alloy coarse wire with a diameter of 0.5 mm.

[0098] Step 9, Annealing: When the tungsten alloy wire obtained in Step 8 is processed to φ0.5mm, it is annealed. After annealing, the tungsten alloy wire is cooled in an oxygen environment. The annealing temperature for φ0.5mm is 1600℃.

[0099] Step 10: The annealed wire obtained in Step 9 is drawn through drawing dies of different specifications, and the drawing is repeated multiple times to a diameter of 58μm, 48μm, 38μm, 28μm and 20μm respectively;

[0100] Step 11, Electrolytic Cleaning: The tungsten alloy wire obtained in Step 10 is first electrolyzed with a 20wt% potassium hydroxide solution containing 15 AC electrolytic plates, and then sequentially electrolyzed with 5 sets of 10wt% potassium hydroxide solutions containing 8 DC electrolytic plates. The electrolysis rate is 180m / min. After electrolysis, the surface is cleaned with deionized water to obtain white fine tungsten wires of different diameters.

[0101] Example 1.2

[0102] The difference between this embodiment and Embodiment 1.1 is that its material element composition includes 0.2wt% gadolinium, 0.2wt% praseodymium, 0.001wt% lutetium, 0.01% carbon, 0.073wt% oxygen, with the balance being tungsten and unavoidable impurities; the remaining preparation steps are the same as in Embodiment 1.1.

[0103] Comparative Example 1.1

[0104] Its material elemental composition includes: 0.8 wt% lanthanum, 0.138 wt% oxygen, with the balance being tungsten and unavoidable impurities;

[0105] The preparation steps are as follows:

[0106] Step 1, doping: A suitable amount of lanthanum nitrate solution is uniformly doped into blue tungsten powder. After thorough stirring, the powder is dried at a low temperature of 80°C for 4 hours and then at a high temperature of 120°C.

[0107] Step 2, Reduction: The material obtained in Step 1 is reduced in a four-temperature zone reduction furnace to reduce the doped powder into alloy powder of suitable particle size in one step.

[0108] Step 3, Mixing: Place the materials obtained in Step 2 into a mixing machine according to their different particle size distributions. Mix at a speed of 8 rpm for 80 minutes;

[0109] Step 4, Powder pressing: Powders of different particle sizes are pressed into compacts weighing 3.0 kg each using isostatic pressing at 200 MPa. The compacts are then pre-sintered at low temperature in a hydrogen atmosphere to increase their strength.

[0110] Step 5, High-temperature sintering: Perform high-temperature sintering to obtain a density of 18.10 g / cm³. 3 sintered billets;

[0111] Step 6, Billet preparation: The sintered billet with a diameter of 23.0 mm is continuously rolled at a heating temperature of 1650℃ using a multi-roll mill to prepare an 8.0 mm alloy rod;

[0112] Step 7, Pressure Processing: Multi-pass rotary forging is adopted. Then, drawing is performed through drawing dies of different specifications. After repeated drawing, alloy wires with diameters of 58μm, 48μm, 38μm, 28μm, and 20μm are produced respectively.

[0113] Comparative Example 1.2

[0114] Its material elemental composition includes: 0.8 wt% cerium, 0.183 wt% oxygen, with the balance being tungsten and unavoidable impurities;

[0115] The preparation steps are as follows:

[0116] Step 1, doping: A suitable amount of lanthanum nitrate solution is uniformly doped into blue tungsten powder. After thorough stirring, the powder is dried at a low temperature of 80°C for 4 hours and then at a high temperature of 120°C.

[0117] Step 2, Reduction: The material obtained in Step 1 is reduced in a four-temperature zone reduction furnace to reduce the doped powder into alloy powder of suitable particle size in one step.

[0118] Step 3, Mixing: Place the materials obtained in Step 2 into a mixing machine according to their different particle size distributions. Mix at a speed of 8 rpm for 80 minutes;

[0119] Step 4, Powder pressing: Powders of different particle sizes are pressed into compacts weighing 3.0 kg each using isostatic pressing at 200 MPa. The compacts are then pre-sintered at low temperature in a hydrogen atmosphere to increase their strength.

[0120] Step 5, High-temperature sintering: Perform high-temperature sintering to obtain a density of 18.10 g / cm³. 3 sintered billets;

[0121] Step 6, Billet preparation: The sintered billet with a diameter of 23.0 mm is continuously rolled at a heating temperature of 1650℃ using a multi-roll mill to prepare an 8.0 mm alloy rod;

[0122] Step 7, Pressure Processing: Multi-pass rotary forging is adopted. Then, drawing is performed through drawing dies of different specifications. After repeated drawing, alloy wires with diameters of 58μm, 48μm, 38μm, 28μm, and 20μm are produced respectively.

[0123] Comparative Example 1.3 (total Z element content exceeds 0.25 wt%)

[0124] The difference from Example 1.1 is that its material element composition includes 0.55wt% gadolinium, 0.55wt% praseodymium, 0.01wt% lutetium, 0.09wt% carbon, 0.2wt% oxygen, and the balance is tungsten and unavoidable impurities; the balance is tungsten and unavoidable impurities; the remaining preparation steps are the same as in Example 1.1.

[0125] Comparative Example 1.4 (total content of L element in the second phase exceeds 1.1 wt%)

[0126] The difference from Example 1.1 is that its material element composition includes: 0.6wt% gadolinium, 0.6wt% praseodymium, 0.01wt% lutetium, 0.03wt% carbon, 0.22wt% oxygen, with the balance being tungsten and unavoidable impurities; the remaining preparation steps are the same as in Example 1.1.

[0127] Comparative Example 2.1 (using deionized water as the solvent for L element)

[0128] Its material element composition is the same as that of Example 1.1. The difference between Comparative Example 2.1 and Example 1.1 is that:

[0129] Step 2, wet doping: The blue tungsten powder obtained in Step 1 is uniformly dispersed in deionized water to obtain a blue tungsten suspension, wherein the volume ratio of blue tungsten powder to deionized water is 1:15; an appropriate amount of carbon powder and deionized water are mixed at a volume ratio of 1:20 to obtain a first suspension; an appropriate amount of gadolinium nitrate, praseodymium nitrate and lutetium nitrate crystalline powders are uniformly dispersed in deionized water and stirred at 1000 r / min in a high-speed emulsification device to form a second suspension; then the first suspension and the second suspension are added to the blue tungsten suspension in sequence and stirred thoroughly and dried to obtain doped blue tungsten, with a stirring speed of 40 r / min and a drying temperature of 160℃; the remaining steps are the same as in Example 1.1.

[0130] Comparative Example 2.2 (Alloy powder was obtained by a single reduction process)

[0131] Its material element composition is the same as that of Example 1.1. The difference between Comparative Example 2.2 and Example 1.1 is that:

[0132] Step 3, powder preparation: The doped blue tungsten powder obtained in step 2 is reduced in a four-temperature zone hydrogen reduction furnace at 650℃, 750℃, 850℃, and 930℃, with a reduction rate of 20 min / boat, to obtain alloy powder with a particle size of 3.0 μm; the remaining steps are the same as in Example 1.1.

[0133] Comparative Example 2.3 (using a conventional drawing pass compression ratio of 10% to 30%)

[0134] Its material element composition is the same as in Example 1.1. The difference between Comparative Example 2.3 and Example 1.1 is that:

[0135] Step 8: The tungsten rod is rough drawn through drawing dies of different specifications. The drawing process is repeated multiple times with a compression ratio of 10% to 30% to obtain tungsten alloy coarse wire with a diameter of 0.5 mm. The remaining steps are the same as in Example 1.1.

[0136] Comparative Example 2.4.1 (cooled in air after annealing)

[0137] Its material element composition is the same as that of Example 1.1. The difference between Comparative Example 2.4.1 and Example 1.1 is that:

[0138] Step 9, Annealing: When the tungsten alloy wire obtained in step 8 is processed to φ0.5mm, it is annealed. After annealing, the tungsten alloy wire is cooled in an air environment. The annealing temperature for φ0.5mm is 1600℃. The remaining steps are the same as in Example 1.1.

[0139] Comparative Example 2.4.2 (cooled in air after annealing)

[0140] Its material element composition is the same as in Example 1.1. The difference between Comparative Example 2.4.2 and Example 1.1 is that:

[0141] Step 9, Annealing: When the tungsten alloy wire obtained in step 8 is processed to φ0.5mm, it is annealed. After annealing, the tungsten alloy wire is cooled in an air environment. The annealing temperature for φ0.5mm is 1650℃. The remaining steps are the same as in Example 1.1.

[0142] Comparative Example 2.4.3 (cooled in air after annealing)

[0143] Its material element composition is the same as that of Example 1.1. The difference between Comparative Example 2.4.3 and Example 1.1 is that:

[0144] Step 9, Annealing: When the tungsten alloy wire obtained in step 8 is processed to φ0.5mm, it is annealed. After annealing, the tungsten alloy wire is cooled in an air environment. The annealing temperature for φ0.5mm is 1700℃. The remaining steps are the same as in Example 1.1.

[0145] Comparative Example 2.4.4 (cooled in air after annealing)

[0146] Its material element composition is the same as that of Example 1.1. The difference between Comparative Example 2.4.4 and Example 1.1 is that:

[0147] Step 9, Annealing: When the tungsten alloy wire obtained in step 8 is processed to φ0.5mm, it is annealed. After annealing, the tungsten alloy wire is cooled in an air environment. The annealing temperature for φ0.5mm is 1550℃. The remaining steps are the same as in Example 1.1.

[0148] Microstructure and performance testing

[0149] The tungsten alloy wires obtained in the examples and comparative examples were subjected to tensile strength tests and characterized by transmission electron microscopy. The γ value was calculated, and the test results are shown in Tables 2-3.

[0150] In this case, the tungsten alloy wires obtained in the examples and comparative examples were cut into thin slices along the axial direction of the tungsten alloy wires using a focused ion beam cutting device. The thin slices were then placed in a high-resolution transmission electron microscope and characterized using different modes. The number of linear second phases and the number of tungsten grains in the sample thin slices were observed, and the γ value was calculated.

[0151] The formula for calculating the γ value is: γ = number of linear second phases / number of tungsten grains.

[0152] The tensile strength test method is as follows: a standard tensile testing machine is used, a 200mm long tungsten wire is clamped, and a constant speed loading is applied to one end to obtain the breaking force data;

[0153] Tensile strength is calculated using the following formula:

[0154] σ = F / S,

[0155] Where F is the breaking force, in N; and S is the original cross-sectional area, in mm.

[0156] Table 2

[0157]

[0158] The " / " indicates that there is no corresponding data.

[0159] The surface defect number, average tungsten grain diameter, radial average width of L or L compound, and dislocation density of the tungsten alloy wires obtained from the measurement examples and comparative examples are shown in Table 3.

[0160] The method for measuring the number of surface defects is as follows: the obtained tungsten alloy wire is subjected to surface defect detection by an eddy current flaw detector, and the flaw detection signal depth exceeding 15% of the diameter is defined as a defect;

[0161] The method for measuring the radial average width of tungsten grains is as follows: a thin slice is cut along the axial direction of the wire using a focused ion beam cutting device. The thin slice is placed in a scanning electron microscope with a backscatter diffraction (EBSD) instrument to collect the morphology of the tungsten grains in the sample to be tested. The width of the upper and lower grain boundaries is measured using conventional measurement software, which is the radial width of the tungsten grains. The average value of the measured widths of multiple tungsten grains is the radial average width of the tungsten grains.

[0162] The radial average width of L or L-type compounds is measured as follows: Figure 1 As shown, a thin slice was cut along the axial direction of the tungsten alloy wire 1 using a focused ion beam cutting device. The slice was placed in a high-resolution transmission electron microscope (HRTEM). The morphology was first observed using a bright-field mode. Surface scanning was performed at locations with significant contrast in morphology, and line scanning was performed perpendicular to the axial direction of the tungsten alloy wire to obtain elemental distribution and composition information. The HRTEM was used to capture images of locations in the sample with significant morphological contrast and elemental distribution differences (i.e., the locations of the aggregation regions of each element in the second phase), obtaining a high-resolution image of the second phase. Fourier transform was performed on the high-resolution image to obtain a lattice diffraction pattern. Using the obtained second-phase diffraction pattern and the elemental composition information of the second phase, the phases corresponding to each diffraction pattern were identified. By comparing with phase cards, it was confirmed that the structure at that location was an L1 or L2 compound phase. The width of the L1 or L2 compound phase was then measured by software. Figure 1 In this diagram, 10 represents the tungsten matrix, and 20 represents L or an L-type compound. The radial average width of the L or L-type compound is calculated by measuring the widths of multiple L-type components. It is understood that this is done for ease of explanation. Figure 1 The image shown is a partial cross-section of the tungsten alloy wire sheet, not the entire sheet.

[0163] The method for testing dislocation density is as follows: a thin slice is cut along the axial direction of a tungsten alloy wire using a focused ion beam cutting device. The slice is then placed in a high-resolution transmission electron microscope to directly observe the lattice pattern and obtain dislocations. The number of dislocation lines passing through a unit cross-sectional area is calculated to obtain the dislocation density.

[0164] Table 3

[0165]

[0166] The " / " indicates that there is no corresponding data.

[0167] The test results in Tables 2 and 3 show that:

[0168] The tungsten alloy wires provided in this application have a tensile strength of over 5000 MPa at a wire diameter of 20–60 μm, and the tensile strength increases with decreasing wire diameter. At 28 μm, the tensile strength can reach over 7000 MPa, and the number of surface defects is less than 10 per 100 meters. At 28 μm, L or L compounds exist in a linear form with a radial average width of less than 4 nm, a radial average width of less than 80 nm for tungsten grains, and a dislocation density > 5*10^6. 9 / mm 2 The number of L or L compounds in the wire / the number of tungsten grains = γ, 3≤γ≤10.

[0169] The comparison results between Comparative Examples 1.1 and 1.2 and Example 1.1 show that:

[0170] The tungsten alloy wire preparation method provided in this application can effectively improve the tensile strength of the wire compared with existing processes. This is because the single nitride (L) element second phase merges and grows during high-temperature sintering and recrystallization annealing, resulting in a wider radial average width of the L element. Furthermore, the second phase particles cause more cracks and wire breakage during subsequent pressure processing, affecting the mechanical strength and processing performance of the tungsten alloy wire. With the rapid increase in cracks, wire breakage during drawing increases significantly. As shown in Table 3, the significant increase in the number of surface defects leads to a deterioration in the wire's processing performance, resulting in a sharp decrease in the average length per coil.

[0171] The comparison results between Comparative Example 1.3 and Example 1.1 show that:

[0172] When the Z element content in the tungsten alloy exceeds 0.25wt%, the Z element forms a solid solution with W, which effectively increases the lattice distortion of tungsten, improves the deformation rate of tungsten wire, and thus improves the tensile strength of tungsten wire. However, the introduction of too much Z element will cause the dislocation density of tungsten alloy wire to increase significantly during the deformation process, which will lead to the work hardening of tungsten alloy wire too fast, making it difficult to refine the wire to below 60μm.

[0173] The comparison results between Comparative Example 1.4 and Example 1.1 show that:

[0174] When the total content of the two L-element second phases in the tungsten alloy composition exceeds 1.1 wt%, the amount of second phase in the tungsten alloy wire is too large, and the ratio γ of the number of second phases to the number of tungsten grains is too high, resulting in insufficient bonding force between the grains of the tungsten alloy wire. At the same time, the increase in the number of second phases will significantly increase the difficulty of dislocation slip, resulting in increased processing difficulty of tungsten alloy wire, making it impossible to process to below 60 μm.

[0175] The comparison results between Comparative Example 2.1 and Example 1.1 show that:

[0176] Compared to the embodiments of this application, when deionized water is used as the solvent for L element in the wet doping step, the tungsten grain size and the average radial width of L increase at the same wire diameter level. This is because the dispersion of L element compounds during the doping process is insufficient, which leads to the local enrichment of L element during the tungsten powder nucleation process in the subsequent reduction process. After high-temperature sintering, these L element compounds grow together and merge, resulting in a significant reduction in the strengthening and refining effect of the actual tungsten grains, and a significant increase in the number of surface defects on the obtained tungsten alloy wire.

[0177] The comparison results between Comparative Example 2.2 and Example 1.1 show that:

[0178] When alloy powder is prepared by a single reduction process in the powder preparation step, the average radial width L increases significantly, and the number of surface defects on the tungsten alloy wire increases significantly, resulting in a much lower tensile strength than in Example 1.1. This is because the tungsten alloy powder prepared by high-temperature single reduction is prone to localized uneven doping during the reduction process, or agglomeration and enrichment after reduction, which leads to microscopic uneven doping of subsequent alloy powder, resulting in defects in the subsequent pressure processing process and reducing the risk of wire breakage.

[0179] The comparison results between Comparative Example 2.3 and Example 1.1 show that:

[0180] When the conventional drawing pass compression ratio of 10% to 30% is used in the pressure processing step, the average radial width of the wires of various specifications is larger, and the average grain size of tungsten grains is greatly increased. This results in more cracks and wire breaks caused by second-phase particles during subsequent pressure processing, which in turn affects the tensile strength.

[0181] This application describes the use of a large compression ratio of 35% to 60% for tungsten alloy wire processing, which results in more developed wire fibers, facilitates the linearization of L elements and their compounds during processing, and accelerates the deformation of tungsten grain boundaries, thereby improving the tensile strength of the wire.

[0182] The number of surface defects and the average length of the tungsten alloy wires obtained in Examples 2.4.1-2.4.4 were measured, and the measurement results are shown in Table 4.

[0183] Table 4

[0184]

[0185] The comparison results between Comparative Examples 2.4.1-2.4.4 and Example 1.1 show that:

[0186] When the surface oxide mass percentage of the tungsten alloy wire is less than 1% during the annealing process, the insufficient surface lubrication layer during multiple drawing processes after annealing leads to a significant increase in the surface hardening rate, resulting in a substantial increase in the number of surface defects. Ultimately, this results in the inability to consistently produce products of the required length. The surface oxide mass percentage of the tungsten alloy wire in this application is greater than or equal to 1%.

[0187] Finally, it should be noted that:

[0188] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A tungsten alloy wire, characterized in that: The tungsten alloy is composed of the following elements in mass fractions: L 0.4–1.1 wt%, X 0.001–0.01 wt%, Z 0.001–0.25 wt%, with the balance being tungsten and unavoidable impurities; Wherein, L is at least one of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; and X is at least one of lutetium, ytterbium, dysprosium, holmium, terbium, and samarium. Z includes oxygen; The wire contains linear L-shaped or L-shaped compounds along the axial direction. When the wire diameter is >50μm and ≤60μm, the radial average width D of L or L compound is ≤5nm, and the tensile strength of the wire is ≥5000MPa. When the wire diameter is >40μm and ≤50μm, the radial average width D of L or L compound is ≤4nm, and the tensile strength of the wire is ≥5500MPa. When the wire diameter is >30μm and ≤40μm, the radial average width D of L or L compound is ≤3nm, and the tensile strength of the wire is ≥6000MPa. When the wire diameter is ≥20μm and ≤30μm, the radial average width D of L or L compound is ≤2nm, and the tensile strength of the wire is ≥7000MPa.

2. The tungsten alloy wire according to claim 1, characterized in that: The Z also includes at least one of carbon, boron, and nitrogen.

3. The tungsten alloy wire according to claim 1, characterized in that: In the wire, the radial average width of the tungsten grains is ≤80nm; The number of L or L compounds in the wire / the number of tungsten grains = γ, 3 ≤ γ ≤ 10.

4. The tungsten alloy wire according to claim 1, characterized in that: The number of surface defects on the wire is ≤10 per 100 meters.

5. The tungsten alloy wire according to claim 1, characterized in that: The dislocation density in the wire is ≥5*10 9 / mm 2 .

6. A method for preparing tungsten alloy wire as described in any one of claims 1-5, characterized in that: This includes wet doping, powder making, pressing, sintering, blanking, and pressure processing.

7. The method for preparing tungsten alloy wire according to claim 6, characterized in that: The wet doping process is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, and nano-sized compound powders of L and X are uniformly dispersed in an alkaline solution with pH > 11 to form a second suspension. Then, the solution containing element Z and the second suspension are sprayed sequentially into the blue tungsten suspension, and after heating and drying, doped blue tungsten powder is obtained. The powder preparation process is as follows: the doped blue tungsten powder is reduced to obtain alloy powder A with a particle size of 1.5-2.6 μm and alloy powder B with a particle size of 3.8-4.5 μm, and then alloy powder A and alloy powder B are mixed to obtain a mixed powder. The sintering process is as follows: the pre-sintered billet obtained by pressing is subjected to electric current sintering, which is carried out in two stages. The first sintering is carried out at 60% of the tungsten bar melting current for 30-45 minutes, followed by cooling. The second sintering is carried out at 90%-92% of the tungsten bar melting current for 40-80 minutes, resulting in a density of 18.6 g / cm³. 3 The above sintered billets; The pressure processing process is as follows: the alloy rod obtained from the blanking is recrystallized and annealed, and then forged into a tungsten rod with a diameter of 2.5 to 4.0 mm by a multi-pass continuous rotary forging equipment. The tungsten rod is then rough drawn through drawing dies of different specifications, and the drawing passes are repeated multiple times with a compression ratio of 35% to 60% to obtain tungsten alloy coarse wire with a diameter of 0.3 to 0.5 mm.

8. The method for preparing tungsten alloy wire according to claim 7, characterized in that: In the wet doping process, the preparation method of the blue tungsten powder is as follows: ammonium paratungstate is fed into a reduction furnace and reduced at 400-600°C under hydrogen and nitrogen protection to obtain blue tungsten powder. The thickness of the ammonium paratungstate powder layer is <10mm. The hydrogen flow rate in the reduction furnace is 20-40L / min, the nitrogen flow rate is 80-160L / min, the oxygen index of the blue tungsten powder is 2.85±0.05, and the ammonium tungsten bronze phase composition is >80%. In the powder preparation process, the reduction method of alloy powder A is as follows: the doped blue tungsten powder is reduced once in a hydrogen reduction furnace at 500-800℃, and then reduced a second time in a hydrogen reduction furnace to obtain alloy powder A with a particle size of 1.5-2.6μm; the reduction method of alloy powder B is as follows: the doped blue tungsten powder is reduced in a hydrogen reduction furnace at 700-1100℃ to obtain alloy powder B with a particle size of 3.8-4.5μm; alloy powder A and alloy powder B are mixed at a mass ratio of 1:(1-2). During the pressure processing, the alloy rod obtained from the blanking is heated to 2000-2600℃ by a medium / high frequency induction coil for recrystallization annealing; the tungsten alloy wire needs to be annealed when it is drawn to a diameter of 0.3-0.5mm, and the annealing temperature is 1300-1800℃. After annealing, the tungsten alloy wire is cooled in an oxygen environment, and then drawn repeatedly to obtain tungsten alloy wires of different diameter specifications.

9. The application of a tungsten alloy wire as described in any one of claims 1-5 in the fields of cutting, cut-resistant protection, cables, screen printing, ropes, or textiles.

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