A tungsten alloy wire, its preparation method and application

Abstract

The present invention relates to the technical field of tungsten alloy materials, and particularly relates to a tungsten alloy wire and its preparation method and application. In terms of mass fraction, the tungsten alloy is composed of the following elements: 0.45 - 0.9 wt% of L, 0.05 - 0.2 wt% of oxygen, and the balance is tungsten and inevitable impurities; wherein, the L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; the wire diameter of the wire is 20 - 60 μm. In the wire, L or a compound of L exists linearly along the axial direction of the wire, and the average width D of L or the compound of L in the radial direction is ≤ 5 nm. By controlling the linear doping of the L element between the tungsten matrixes and making the radial average width D of L ≤ 5 nm, the crack breakage caused by the second-phase particles during the subsequent hot working process is greatly reduced, which is beneficial to ensuring the mechanical strength of the tungsten alloy wire. When the wire diameter of the wire is 20 - 60 μm, the wire has a tensile strength of more than 5000 MPa, and at the same time, the processing performance of the tungsten alloy wire is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of tungsten alloy materials, and particularly relates to a tungsten alloy wire and a preparation method and application thereof. Background Art

[0002] Tungsten alloy is an alloy composed of tungsten as the base and other elements added. Among metals, tungsten has the highest melting point, good high-temperature strength, creep resistance, thermal conductivity, electrical conductivity and electron emission performance, and a large specific gravity. In addition to being widely used in the manufacture of cemented carbide and as an alloy additive, tungsten alloy is widely used in the fields of aerospace, medical treatment, automobile, electronics, etc.

[0003] In order to further improve the processing performance of tungsten alloy materials, rare earth elements such as lanthanum, cerium, praseodymium, neodymium, etc. are currently doped into the tungsten matrix to disperse and strengthen the tungsten material. However, rare earth elements are used as the second phase in the tungsten matrix, and during the processing, they are prone to solid-liquid phase transformation during high-temperature sintering and recrystallization annealing. Among them, these second-phase particles will merge and grow, resulting in more cracks at the interface between the second-phase particles and the tungsten wire. In order to avoid wire breakage on the wire during subsequent processing caused by cracks, the wire can only be limited to a certain size, which is not conducive to the refinement of tungsten alloy wire. Summary of the Invention

[0004] To solve the problem that the introduction of the second phase in the prior art leads to more cracks and wire breakage in tungsten alloy wire, the present invention provides a tungsten alloy wire. In terms of mass fraction, the tungsten alloy is composed of the following elements: 0.45 - 0.9 wt% L, 0.05 - 0.2 wt% oxygen, and the balance is tungsten and unavoidable impurities;

[0005] Wherein, the L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium;

[0006] For example, L is lanthanum, or cerium, or praseodymium, or neodymium, or lanthanum and cerium, or lanthanum and praseodymium, or lanthanum and gadolinium, or cerium and neodymium, or praseodymium and gadolinium, or neodymium and samarium, or lanthanum, cerium and praseodymium, or lanthanum, cerium and gadolinium, or cerium, praseodymium, neodymium and gadolinium, etc.;

[0007] For another example, the mass fraction of L is 0.45% - 0.9%, or 0.5% - 0.9%, or 0.7% - 0.9%, or 0.45% - 0.5%, or 0.45% - 0.8%, or 0.45%, 0.5%, 0.55%, 0.6%, 0.7%, 0.8%, 0.85%, etc.;

[0008] The mass fraction of oxygen is 0.05 - 0.2%, or 0.05 - 0.18%, or 0.1 - 0.2%, or 0.14%, 0.15%, 0.1%, 0.13%, 0.16%, 0.2, etc.

[0009] The wire diameter of the wire is 20-60 μm, such as 20 μm, 28 μm, 30 μm, 38 μm, 40 μm, 48 μm, 50 μm, 55 μm, 58 μm, 60 μm, etc. The tungsten alloy wire can be uniform, or can be incompletely uniform, and can also contain differences of several percentages such as 1% according to the parts.

[0010] In the wire, L or the compound of L exists linearly along the axial direction of the wire, and the average width D along the radial direction of the compound of L or L is ≤ 5 nm. It should be noted that "linearly" means that the size of the compound of L or L along the axial direction of the wire in the wire is much larger than the size along the radial direction of the wire.

[0011] Among them, the compound of L can be an oxide, such as lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, gadolinium oxide, samarium oxide, etc. Of course, it can also be other forms of compounds.

[0012] Furthermore, the proportion of the grain boundaries of tungsten grains in the wire with an angle ≤ 15° ≥ 50%.

[0013] Furthermore, the average width of tungsten grains along the radial direction in the wire is ≤ 80 nm.

[0014] Furthermore, when the wire diameter of the wire is > 50 μm and ≤ 60 μm, the average width D along the radial direction of the compound of L or L is ≤ 5 nm, and the tensile strength of the wire is ≥ 5000 MPa;

[0015] When the wire diameter of the wire is > 40 μm and ≤ 50 μm, the average width D along the radial direction of the compound of L or L is ≤ 4 nm, and the tensile strength of the wire is ≥ 5500 MPa;

[0016] When the wire diameter of the wire is > 30 μm and ≤ 40 μm, the average width D along the radial direction of the compound of L or L is ≤ 3 nm, and the tensile strength of the wire is ≥ 6000 MPa;

[0017] When the wire diameter of the wire is ≥ 20 μm and ≤ 30 μm, the average width D along the radial direction of the compound of L or L is ≤ 2 nm, and the tensile strength of the wire is ≥ 7000 MPa.

[0018] The present invention also provides a preparation method of the above tungsten alloy wire, including wet doping, powder making, pressing, sintering, cogging, hot working and electrolytic cleaning.

[0019] Furthermore, the wet doping is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, the nano-scale compound powder of L is uniformly dispersed in an alkaline solution with pH > 11 to form a second suspension, and then the second suspension is sprayed into the blue tungsten suspension, and after heating and drying, doped blue tungsten powder is obtained.

[0020] Preferably, the nanoscale compound powder of L is uniformly dispersed in an alkaline solution with pH > 11, and then rapidly stirred by a stirring device at 1000 - 2000 r / min.

[0021] The preferred drying method is rapid vacuum heating and drying.

[0022] By preparing a compound suspension of element L, fine particles are directly and uniformly doped into blue tungsten powder. The fine particles serve as heterogeneous crystal nuclei and co-precipitate with tungsten particles. The tungsten alloy powder prepared in this way has a more uniform dispersion distribution. This method does not need to adopt the form of element salts, and has a wider selection range of dispersive particles, and the obtained tungsten material has more stable and reliable performance.

[0023] Furthermore, the method for preparing the blue tungsten powder is as follows: Ammonium paratungstate is fed into a reduction furnace and reduced under the protection of hydrogen and nitrogen at 400 - 600 °C to obtain blue tungsten powder. The thickness of the ammonium paratungstate powder layer is < 10 mm. The hydrogen flow rate in the reduction furnace is 20 - 40 L / min, and the nitrogen flow rate is 80 - 160 L / min. The oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the content of the ammonium tungsten bronze phase is > 80%.

[0024] The preparation of blue tungsten powder uses a hydrogen-nitrogen mixed gas as the reduction protection medium. The performance of the discharged blue tungsten powder is controlled by the thickness of the powder layer, the size and flow direction of hydrogen. Blue tungsten with an oxygen index of 2.85 ± 0.05 and an ammonium tungsten bronze phase ratio exceeding 80% is doped. This blue tungsten has coarse particles and many surface cracks, which is beneficial for the entry of the rare earth solution, improving the doping effectiveness, enhancing the uniformity of the second-phase distribution in the tungsten wire, and improving the comprehensive mechanical properties and processing performance of the tungsten wire.

[0025] Furthermore, the powder making 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 respectively, and then alloy powder A and alloy powder B are mixed evenly to obtain a mixed powder.

[0026] Preferably, the reduction method of alloy powder A is: The doped blue tungsten powder is first reduced in a hydrogen reduction furnace at 500 - 800 °C, and then secondarily reduced in a hydrogen reduction furnace at 700 - 1000 °C to obtain alloy powder A with a particle size of 1.5 - 2.6 μm.

[0027] Preferably, the reduction method of alloy powder B is: The doped blue tungsten powder is 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.

[0028] Preferably, alloy powder A and alloy powder B are mixed evenly at a mass ratio of 1:(1 - 2).

[0029] Fine-grained tungsten alloy powder is prepared by two-stage reduction and mixed with coarse-grained tungsten alloy powder prepared by high-temperature single-stage reduction in a certain proportion, which not only avoids local uneven doping during the reduction process of coarse-grained powder, but also effectively inhibits the agglomeration and enrichment of fine-grained powder after reduction, preventing the generation of defects in the subsequent pressure processing due to microscopically uneven doping of the alloy powder and reducing the risk of wire breakage.

[0030] Further, the sintering is specifically: subjecting the pre-sintered blank obtained by pressing to high-temperature sintering at 2200 - 2800 °C.

[0031] Further, the pressure processing is as follows: subjecting the alloy rod obtained by cogging to recrystallization annealing, and then forging it to a tungsten rod with a diameter of 2.5 - 4.0 mm through a multi-pass continuous rotary forging device. The tungsten rod is subjected to rough drawing through wire drawing dies of different specifications, and the drawing pass reduction ratio of 35% - 60% is repeated multiple times to obtain a tungsten alloy thick wire with a diameter of 0.3 - 0.5 mm.

[0032] Processing tungsten alloy wire with a large reduction ratio of 35% - 60% results in more developed wire fibers, which is beneficial to the linearization of element L and its compounds during the processing, thereby improving the breaking force of the wire.

[0033] Further, during the pressure processing, the alloy rod obtained by cogging is heated to 2000 - 2600 °C through a medium / high-frequency induction coil for recrystallization annealing.

[0034] Further, when the tungsten alloy wire is drawn to a diameter of 0.3 - 0.5 mm, annealing treatment is required. The annealing temperature is 1300 - 1700 °C. After annealing, the tungsten alloy wire is cooled in an oxygen environment. The cumulative processing deformation rate after annealing is ≥95%. After annealing, drawing is repeated multiple times to obtain tungsten alloy wires with different diameter specifications. When the tungsten alloy wire is drawn to less than 0.3 mm, no further annealing treatment is performed.

[0035] By subjecting the wire to annealing and then oxygen cooling treatment, the content and thickness of the oxide layer on the surface of the tungsten alloy wire can be increased, effectively improving the lubricating layer of the wire, thus improving the drawing conditions, ensuring the feasibility of large reduction ratio drawing of the wire, and significantly reducing the probability of wire breakage.

[0036] The wire after annealing and cooling is drawn through wire drawing dies of different specifications, and drawing is repeated multiple times to draw it to the required wire diameter.

[0037] Further, the electrolytic cleaning is as follows: first subjecting the prepared tungsten alloy wire to high-concentration alkali solution and alternating current electrolysis, and then using low-concentration alkali solution and direct current electrolysis.

[0038] Preferably, the obtained tungsten alloy wire is first electrolyzed through a potassium hydroxide solution with a concentration of 20 wt% to 30 wt% and containing 8 to 15 groups of alternating current electrolysis sheets, and then electrolyzed successively through 5 to 8 groups of potassium hydroxide solutions with a concentration of 5 wt% to 10 wt% and containing 5 to 10 groups of direct current electrolysis sheets, and then the surface is cleaned with deionized water, wherein the electrolysis speed is 50 to 200 m / min.

[0039] By using a high-concentration alkali solution and an alternating current electrolysis method to first strip the surface layer of the black tungsten wire, the surface graphite layer and tungsten oxide layer can be quickly removed, and at the same time, the surface grooves of the wire can be effectively eliminated. Then, the tungsten wire is subjected to electrolytic polishing treatment successively through a low-concentration alkali solution and a direct current pulse mode. The obtained wire has better diameter uniformity, and can effectively ensure that the wire diameter tolerance reaches within ±1% of the diameter.

[0040] The present invention also provides an application of the above-mentioned tungsten alloy wire in the fields of cutting, cutting resistance protection, cables, screen printing, ropes or textiles.

[0041] Compared with the prior art, the tungsten alloy wire provided by the present invention has the following advantages:

[0042] The present invention uses one or more of rare earth elements / rare earth compounds as the second-phase strengthening tungsten material. By controlling L or a compound of L to be linearly doped between tungsten matrices, and making the average width of L or a compound of L along the radial direction ≤ 5 nm, the crack breakage caused by second-phase particles during the subsequent hot working process is greatly reduced, which is beneficial to ensuring the mechanical strength of the tungsten alloy wire. When the wire diameter is 20 to 60 μm, the tensile strength is above 5000 MPa, and at the same time, the processing performance of the tungsten alloy wire is enhanced. Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0044] Figure 1 It is a schematic diagram of the method for measuring the average width of the compound of L or L along the radial direction provided by the present invention. Detailed Embodiments

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] The present invention provides a tungsten alloy wire. In terms of mass fraction, the tungsten alloy is composed of the following elements: 0.45 - 0.9 wt% L, 0.05 - 0.2 wt% oxygen, and the balance is tungsten and inevitable impurities.

[0047] Among them, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium.

[0048] It can be understood that the inevitable impurities are other elements introduced during the preparation process.

[0049] The wire diameter of the wire is 20 - 60 μm. In the wire, L or the compound of L exists linearly along the axial direction of the wire, and the average width D of the L or the compound of L in the radial direction is ≤ 5 nm.

[0050] The proportion of the grain boundaries of tungsten grains in the wire with an angle ≤ 15° ≥ 50%.

[0051] The average width of tungsten grains in the wire in the radial direction is ≤ 80 nm.

[0052] When the wire diameter of the wire is > 50 μm and ≤ 60 μm, the average width D of the L or the compound of L in the radial direction is ≤ 5 nm, and the tensile strength of the wire is ≥ 5000 MPa.

[0053] When the wire diameter of the wire is > 40 μm and ≤ 50 μm, the average width D of the L or the compound of L in the radial direction is ≤ 4 nm, and the tensile strength of the wire is ≥ 5500 MPa.

[0054] When the wire diameter of the wire is > 30 μm and ≤ 40 μm, the average width D of the L or the compound of L in the radial direction is ≤ 3 nm, and the tensile strength of the wire is ≥ 6000 MPa.

[0055] When the wire diameter of the wire is ≥ 20 μm and ≤ 30 μm, the average width D of the L or the compound of L in the radial direction is ≤ 2 nm, and the tensile strength of the wire is ≥ 7000 MPa.

[0056] The present invention provides a method for preparing a tungsten alloy wire, including wet doping, powder making, pressing, sintering, cogging, hot working, electrolytic cleaning, etc.

[0057] Among them, the wet doping is as follows: uniformly disperse blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly disperse L nanoscale compound powder in an alkaline solution with pH > 11 to form a second suspension, then spray the second suspension onto the blue tungsten suspension, and after spraying, perform rapid vacuum heating and drying to obtain doped blue tungsten powder;

[0058] The preparation method of the blue tungsten powder is as follows: feed ammonium paratungstate into a reduction furnace, and perform reduction under the protection of hydrogen and nitrogen at 400 - 600 °C to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer < 10 mm, the hydrogen flow rate in the reduction furnace is 20 - 40 L / min, the nitrogen flow rate is 80 - 160 L / min, the oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the ammonium tungsten bronze phase composition > 80%;

[0059] The powder making is as follows: perform primary reduction on the doped blue tungsten powder in a hydrogen reduction furnace at 500 - 800 °C, and then perform secondary 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;

[0060] Reduce 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;

[0061] Mix alloy powder A and alloy powder B in a mass ratio of 1:(1 - 2) to obtain a mixed powder;

[0062] The sintering is as follows: perform high-temperature sintering on the pre-sintered blank obtained by pressing at 2200 - 2800 °C to obtain a sintered blank with a density of 18.6 g / cm 3 above;

[0063] Preferably, the sintering is carried out in a hydrogen atmosphere, where the hydrogen purity > 99.5%;

[0064] The pressure processing is as follows: heat the alloy rod obtained by cogging to 2000 - 2600 °C through a medium / high-frequency induction coil for recrystallization annealing, and then forge it through a multi-pass continuous rotary forging equipment to a tungsten rod with a diameter of 2.5 - 4.0 mm;

[0065] Perform rough drawing processing on the tungsten rod through different specifications of wire drawing dies, and repeat the drawing pass reduction ratio of 35% - 60% to obtain a tungsten alloy thick wire with a diameter of 0.3 - 0.5 mm;

[0066] When the tungsten alloy wire is drawn to a diameter of 0.3 - 0.5 mm, annealing treatment is required, and the annealing temperature is 1300 - 1700 °C. After annealing, the tungsten alloy wire is cooled in an oxygen environment, and the cumulative processing deformation rate after annealing ≥ 95%.

[0067] The wire after annealing and cooling is drawn through drawing dies of different specifications, and is drawn to the required wire diameter through repeated drawing for multiple times.

[0068] In addition, for the pressing and blanking steps in the above steps, the following implementation manners are preferably but not limited to:

[0069] Pressing: The mixed powder is pressed into a green compact with a single weight of 1.5 - 6 kg under a pressure of 140 - 240 MPa by isostatic pressing, and the green compact is subjected to low-temperature pre-sintering at 1200 - 1400 °C for 10 - 30 minutes in a hydrogen atmosphere to increase the strength of the green compact;

[0070] Blanking: A multi-roll mill is used to continuously roll the sintered billet with a diameter of 15 - 25 mm into an alloy rod with a diameter of 8.0 - 12.0 mm at 1600 - 1700 °C.

[0071] The preparation method further includes electrolytic cleaning: The prepared tungsten alloy wire is first electrolyzed through a potassium hydroxide solution with a concentration of 20 wt% - 30 wt% and containing 8 - 15 groups of alternating current electrolytic sheets, and then electrolyzed through a potassium hydroxide solution with a concentration of 5 wt% - 10 wt% and containing 5 - 10 groups of direct current electrolytic sheets in sequence for 5 - 8 groups, and then the surface is cleaned with deionized water, where the electrolysis speed is 50 - 200 m / min.

[0072] Therefore, the present invention provides the tungsten alloy element compositions of the following examples and comparative examples as shown in Table 1:

[0073] Table 1 (unit: wt%):

[0074]

[0075] Among them, "-" indicates that the corresponding element is not added.

[0076] Example 1.1

[0077] This example prepares a tungsten alloy wire according to the present invention. In terms of mass fraction, its material element components include: cerium 0.6 wt%, oxygen 0.137 wt%, and the balance is tungsten and unavoidable impurities.

[0078] Its preparation steps are as follows:

[0079] Step 1. Prepare blue tungsten: Ammonium paratungstate powder is subjected to hydrogen reduction through a reverse hydrogen continuous reduction furnace at 400 °C, 450 °C, 500 °C, and 560 °C. The thickness of the ammonium paratungstate powder layer is 8 mm, the hydrogen flow rate is 30 L / min, and the nitrogen flow rate is 140 L / min to obtain blue tungsten powder, whose oxygen index is 2.87 and the ammonium tungsten bronze phase composition is 82%;

[0080] Step 2, Wet doping: The blue tungsten powder obtained in Step 1 is evenly dispersed in deionized water to obtain a blue tungsten suspension, where the volume ratio of the blue tungsten powder to deionized water is 1:15; an appropriate amount of cerium oxide nano-powder is evenly dispersed in a sodium hydroxide solution with a pH of 13, and high-speed stirring is carried out at 1500 r / min in a high-speed emulsification device to form a second suspension. Then, the second suspension is sprayed onto the blue tungsten suspension through a vacuum pipeline. After spraying, rapid vacuum heating and drying are carried out to obtain doped blue tungsten powder;

[0081] Step 3, Powder making: The doped blue tungsten powder obtained in Step 2 is first reduced in a three-zone hydrogen reduction furnace at 500 °C, 650 °C, and 750 °C, and then secondarily reduced in a four-zone hydrogen reduction furnace at 700 °C, 810 °C, 870 °C, and 920 °C to obtain alloy powder A with a particle size of 2.0 μm;

[0082] The doped blue tungsten powder obtained in Step 2 is reduced in a four-zone hydrogen reduction furnace at 720 °C, 820 °C, 870 °C, and 950 °C to obtain alloy powder B with a particle size of 4.1 μm;

[0083] The alloy powder A and alloy powder B are placed in a high-energy powder mixer in a mass ratio of 1:1.5 and mixed for 120 minutes to obtain a mixed powder, and the particle size of the mixed powder is 3.0 μm;

[0084] Step 4, Pressing: The mixed powder obtained in Step 3 is pressed into a green compact with a single weight of 3 kg under an isostatic pressure of 160 MPa, and the green compact is pre-sintered at 1300 °C in a hydrogen atmosphere for 20 minutes to obtain a pre-sintered blank bar;

[0085] Step 5, Sintering: The pre-sintered blank bar obtained in Step 4 is subjected to high-temperature sintering at 2600 °C to obtain a sintered blank bar with a density of 18.68 g / cm 3 ;

[0086] Step 6, Blooming: The sintered blank bar with a diameter of 20 mm is bloomed into an alloy rod with a diameter of 8.0 mm by continuous rolling at a heating temperature of 1600 °C using a multi-roll mill;

[0087] Step 7, Pressure processing: The alloy rod obtained in Step 6 is heated to 2400 °C by a high-frequency induction coil for recrystallization annealing, and then forged to a tungsten rod with a diameter of 3.0 mm through a multi-pass continuous swaging device;

[0088] Step 8, The tungsten rod is subjected to rough drawing processing through wire drawing dies of different specifications, and the drawing pass reduction ratio is repeated multiple times at 35% - 60% to obtain a tungsten alloy thick wire with a diameter specification of 0.4 mm;

[0089] Step 9. Annealing: The tungsten alloy thick wire obtained in Step 8 is annealed, and after annealing, the tungsten alloy wire is cooled in an oxygen environment. The annealing temperature is 1650 °C, and the mass percentage of the oxide on the wire surface is 1.18%.

[0090] Step 10. The annealed wire obtained in Step 9 is drawn through drawing dies of different specifications, and is drawn to diameters of 60 μm, 48 μm, 38 μm, 28 μm, and 20 μm respectively by repeating drawing multiple times.

[0091] Step 11. Electrolytic cleaning: The tungsten alloy wire obtained in Step 10 is first electrolyzed through a potassium hydroxide solution with a concentration of 22 wt%, which contains 12 groups of AC electrolytic sheets, and then electrolyzed through 6 groups of potassium hydroxide solutions with a concentration of 6 wt% in sequence, which contains 5 groups of DC electrolytic sheets. The electrolysis speed is 180 m / min. After electrolysis, the surface is cleaned with deionized water to obtain white fine tungsten wires with different wire diameters.

[0092] Example 1.2

[0093] This example prepares a tungsten alloy wire according to the present invention. By mass fraction, its material element components include: lanthanum 0.45 wt%, oxygen 0.078 wt%, and the balance is tungsten and inevitable impurities.

[0094] Its preparation steps are the same as those of Example 1.1 except that cerium oxide in Step 2 is replaced by lanthanum oxide.

[0095] Example 1.3

[0096] This example prepares a tungsten alloy wire according to the present invention. By mass fraction, its material element components include: neodymium 0.75 wt%, oxygen 0.125 wt%, and the balance is tungsten and inevitable impurities.

[0097] Its preparation steps are the same as those of Example 1.1 except that cerium oxide in Step 2 is replaced by neodymium oxide.

[0098] Example 1.4

[0099] This example prepares a tungsten alloy wire according to the present invention. By mass fraction, its material element components include: lanthanum 0.35 wt%, praseodymium 0.4 wt%, oxygen 0.13 wt%, and the balance is tungsten and inevitable impurities.

[0100] Its preparation steps are the same as those of Example 1.1 except that cerium oxide in Step 2 is replaced by lanthanum oxide and praseodymium oxide.

[0101] Example 1.5

[0102] In this embodiment, a tungsten alloy wire is prepared according to the present invention. By mass fraction, the elemental components of the material include: gadolinium 0.35 wt%, praseodymium 0.4 wt%, oxygen 0.115 wt%, and the balance is tungsten and unavoidable impurities.

[0103] The preparation steps are the same as those in Example 1.1, except that cerium oxide in Step 2 is replaced by gadolinium oxide and praseodymium oxide.

[0104] Example 1.6

[0105] In this embodiment, a tungsten alloy wire is prepared according to the present invention. By mass fraction, the elemental components of the material include: samarium 0.35 wt%, gadolinium 0.4 wt%, oxygen 0.172 wt%, and the balance is tungsten and unavoidable impurities.

[0106] The preparation steps are the same as those in Example 1.1, except that cerium oxide in Step 2 is replaced by samarium oxide and gadolinium oxide.

[0107] Example 1.7

[0108] In this embodiment, a tungsten alloy wire is prepared according to the present invention. The elemental components of the material are the same as those in Example 1.1. The difference in the preparation steps from Example 1.1 is that in Step 3, powder A and powder B of the alloy are mixed evenly at a ratio of 1:4. The remaining preparation steps are the same as those in Example 1.1.

[0109] Comparative Example 2.1

[0110] In this embodiment, a tungsten alloy wire is prepared according to the present invention. By mass fraction, the elemental components of the material include: cerium 0.92 wt%, oxygen 0.21 wt%, and the balance is tungsten and unavoidable impurities.

[0111] The preparation steps are the same as those in Example 1.1.

[0112] Comparative Example 2.2

[0113] In this embodiment, a tungsten alloy wire is prepared according to the present invention. By mass fraction, the elemental components of the material include: cerium 0.4 wt%, lanthanum 0.52 wt%, oxygen 0.181 wt%, and the balance is tungsten and unavoidable impurities.

[0114] The preparation steps are the same as those in Example 1.1, except that the second suspension in Step 2 further includes lanthanum oxide.

[0115] Comparative Example 2.3

[0116] In this embodiment, a tungsten alloy wire is prepared according to the present invention. By mass fraction, the elemental components of the material include: cerium 0.43 wt%, oxygen 0.098 wt%, and the balance is tungsten and unavoidable impurities.

[0117] The preparation steps are the same as those in Example 1.1.

[0118] Comparative Example 2.4

[0119] In this example, a tungsten alloy wire is prepared according to the present invention. The material element components are the same as those in Example 1.1. The difference in the preparation steps from Example 1.1 is as follows: Step 8: The tungsten rod is subjected to rough drawing through wire drawing dies of different specifications, and the drawing pass reduction ratio is 35% - 60% for multiple repeated drawing passes to obtain a tungsten alloy thick wire with a diameter of 0.2 mm; Step 9: Annealing: The tungsten alloy thick wire obtained in Step 8 is annealed, and after annealing, the tungsten alloy wire is cooled in an oxygen environment, where the annealing temperature is 1650 °C and the mass percentage of the oxide on the wire surface is 1.35%.

[0120] The remaining steps are all the same as those in Example 1.1.

[0121] Comparative Example 2.5

[0122] In this example, a tungsten alloy wire is prepared according to the present invention. The material element components are the same as those in Example 1.1. The difference in the preparation steps from Example 1.1 is as follows: Step 8: The tungsten rod is subjected to wire drawing through wire drawing dies of different specifications, and the drawing pass reduction ratio is 10% - 30% for multiple repeated drawing passes to obtain a tungsten alloy thick wire with a diameter of 0.4 mm.

[0123] The remaining steps are all the same as those in Example 1.1.

[0124] Comparative Example 2.6

[0125] In this example, a tungsten alloy wire is prepared according to the present invention. The material element components are the same as those in Example 1.1. The difference in the preparation steps from Example 1.1 is as follows: Step 2: Wet doping: The blue tungsten powder obtained in Step 1 is uniformly dispersed in deionized water to obtain a blue tungsten suspension, where the volume ratio of the blue tungsten powder to deionized water is 1:15. An appropriate amount of cerium oxide nanoscale powder is dissolved in deionized water and added to the above blue tungsten suspension, and then stirred and dried thoroughly to obtain doped blue tungsten. The stirring speed is 40 r / min, and the drying temperature is 160 °C.

[0126] The remaining steps are all the same as those in Example 1.1.

[0127] Performance Test

[0128] The wires obtained in Examples 1.1 - 1.7 and Comparative Examples 2.1 - 2.3 are subjected to tensile strength tests, and the average diameter of tungsten grains and the average width of L or the compound of L along the radial direction are measured. The test results are shown in Table 2. Among them, the tensile strength test method: Using a standard tensile testing machine, a 200 - mm - long tungsten wire is clamped, and one end is loaded at a constant speed to obtain the breaking force data.

[0129] The tensile strength is calculated by the following formula:

[0130] σ = F / S,

[0131] where F is the breaking force, in N; S is the original cross-sectional area, in mm²;

[0132] The method for measuring the average width of tungsten grains along the radial direction is as follows: Use a focused ion beam cutting device to cut out a thin slice along the axial direction of the wire. Place the thin slice in a scanning electron microscope equipped with an electron backscatter diffraction (EBSD) instrument, collect the morphology of the tungsten grains of the sample to be measured, and use conventional measurement software to measure the widths of the upper and lower grain boundaries, which is the radial width of the tungsten grains. Calculate the average value of the diameters of multiple measured tungsten grains to obtain the average width of the tungsten grains along the radial direction.

[0133] The method for measuring the average width of L or a compound of L along the radial direction is as follows: Figure 1 As shown, use a focused ion beam cutting device to cut out a thin slice along the axial direction of the tungsten alloy wire 1. Place the thin slice in a high-resolution transmission electron microscope. First, observe the morphology in the bright and dark field modes, select positions with obvious contrast differences in morphology, perform area scanning, and perform line scanning perpendicular to the axial position of the tungsten alloy wire to obtain the element distribution and element composition information. Take pictures of the positions in the test sample with obvious contrast in morphology and obvious element distribution differences (i.e., the positions of the aggregation regions of the elements of the second phase) through the transmission electron microscope to obtain a high-resolution image of the second phase. Perform a Fourier transform on the high-resolution image to obtain a lattice diffraction spectrum. Using the obtained diffraction spectrum of the second phase and combining the element composition information of the second phase, calibrate the phases corresponding to each diffraction spectrum. After confirming that it is the phase structure of L or a compound of L by comparing with the phase card, the software measures the width of L or a compound of L; Figure 1 In the figure, 10 represents the tungsten matrix, and 20 represents L or a compound of L. Calculate the average value by measuring the widths of multiple Ls respectively, which is the average radial width of L or a compound of L. It can be understood that for the sake of convenience of explanation, Figure 1 the intercepted part is a local cross-section of the thin slice of the tungsten alloy wire, not the entire picture of the thin slice.

[0134] Table 2

[0135]

[0136]

[0137] where " / " indicates that there is no corresponding data.

[0138] As can be seen from Table 2, the tungsten alloy wire provided by the embodiment of the present invention has a tensile strength of more than 5000 MPa at a wire diameter of 20-60 μm, and as the wire diameter decreases, its tensile strength increases. When the wire diameter is 28 μm, its tensile strength can reach more than 7000 MPa; moreover, in the tungsten alloy wire provided by the embodiment of the present invention, L or the compound of L exists in a linear shape, and its average width along the radial direction is less than 5 nm, and the average width of tungsten grains along the radial direction is less than 80 nm.

[0139] From the comparison results of Comparative Examples 2.1-2.3 and Example 1.1, it can be seen that when the L content in the tungsten alloy wire is greater than 0.9 wt%, the number of second phases in the tungsten alloy wire is too large, resulting in insufficient bonding force between the tungsten alloy wire grains. At the same time, the increase in the number of second phases will greatly increase the difficulty of dislocation slip, resulting in an increase in the processing difficulty of the tungsten alloy wire and making it impossible to process it below 60 μm; when the L content in the tungsten alloy wire is less than 0.45 wt%, the strengthening effect of the second phase on the tungsten alloy wire is not obvious, thus resulting in a decrease in the tensile strength.

[0140] From the comparison results of Comparative Example 2.6 and Example 1.1, it can be seen that the average width of tungsten grains along the radial direction of the wire obtained by the doping method of this patent is finer, and the size of the second-phase particles is also more slender. This is because this patent uses dispersed nano-scale powder particles to enter the tungsten powder during the early doping process, and its dispersion uniformity is better. At the same time, because there are more second-phase particles in the tungsten grains after the particles are reduced, its effect of refining tungsten grains is better. At the same time, the fine second-phase particles can better hinder the deformation of tungsten grains, thereby improving the overall tensile strength of the tungsten wire.

[0141] The wires obtained in Example 1.1 and Comparative Examples 2.4 and 2.5 were tested for tensile strength, and the proportion of grain boundary angles was measured, and the cumulative processing deformation rate of the wires was calculated. The test results are shown in Table 3.

[0142] Among them, the method for measuring the proportion of grain boundary angles is as follows: Use a focused ion beam cutting device to cut out a thin slice along the axial direction of the tungsten alloy wire, place the thin slice in a scanning electron microscope equipped with an electron backscatter diffraction (EBSD) instrument, collect the orientation difference information between the tungsten grains of the thin slice to be measured and the surrounding tungsten grains, and measure the proportion of grain boundaries with an angle difference ≤ 15°.

[0143] The formula for the cumulative processing deformation rate of the wire is: 1 - D1*D1 / (D2*D2);

[0144] where D1 is the wire diameter of the finished wire and D2 is the wire diameter during annealing treatment.

[0145] Table 3

[0146]

[0147] Among them, " / " indicates that there is no corresponding data.

[0148] From the comparison results between Comparative Example 2.4 and Example 1.1, it can be seen that when the tungsten alloy wire is annealed with a wire diameter less than 0.3 mm, the proportion of tungsten grain boundaries with an angle ≤ 15° in the obtained product is relatively small, resulting in more crack breakage caused by the second-phase particles during the subsequent hot working process, and thus affecting the tensile strength.

[0149] From the comparison results between Comparative Example 2.5 and Example 1.1, it can be seen that when the conventional drawing pass reduction ratio of 10% - 30% is adopted in the hot working step, the average width of L in the obtained wires of each specification is relatively large, and the proportion of tungsten grain boundaries with an angle ≤ 15° is relatively small, resulting in more crack breakage caused by the second-phase particles during the subsequent hot working process, and thus affecting the tensile strength and unable to be processed to less than 40 microns. It shows that when processing tungsten alloy wires with a large reduction ratio of 35% - 60%, the obtained wire fibers are more developed, which is beneficial to the fibrosis of L element and its compounds during the processing, and the deformation degree of tungsten grain boundaries is faster, so as to improve the tensile strength of the wire. At the same time, through the setting of the annealing point, by increasing the cumulative deformation amount after high-temperature annealing and improving the deformation degree of the wire, the proportion of small-angle tungsten grain boundaries is increased to further improve the tensile strength of tungsten wires.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tungsten alloy wire, characterized in that: By mass fraction, the tungsten alloy is composed of the following elements: 0.45 - 0.9 wt% L, 0.05 - 0.2 wt% oxygen, and the balance is tungsten and inevitable impurities; wherein, the L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; The wire diameter of the wire is 20 - 60 μm. In the wire, L or a compound of L exists linearly along the axial direction of the wire, and the average width D of the L or the compound of L in the radial direction is ≤ 5 nm; The average width of tungsten grains in the wire in the radial direction is ≤ 80 nm; The proportion of the grain boundary angle of tungsten grains in the wire being ≤ 15° is ≥ 50%; 2. The tungsten alloy wire according to claim 1, characterized in that: When the wire diameter of the wire is > 50 μm and ≤ 60 μm, the average width D of the L or the compound of L in the radial direction is ≤ 5 nm, and the tensile strength of the wire is ≥ 5000 MPa; When the wire diameter of the wire is > 40 μm and ≤ 50 μm, the average width D of the L or the compound of L in the radial direction is ≤ 4 nm, and the tensile strength of the wire is ≥ 5500 MPa; When the wire diameter of the wire is > 30 μm and ≤ 40 μm, the average width D of the L or the compound of L in the radial direction is ≤ 3 nm, and the tensile strength of the wire is ≥ 6000 MPa; When the wire diameter of the wire is ≥ 20 μm and ≤ 30 μm, the average width D of the L or the compound of L in the radial direction is ≤ 2 nm, and the tensile strength of the wire is ≥ 7000 MPa; 3. A method for preparing the tungsten alloy wire according to claim 1 or 2, characterized in that: It includes wet doping, powder making, pressing, sintering, cogging, hot working, and electrolytic cleaning; The wet doping is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, nano - scale compound powder of L is uniformly dispersed in an alkaline solution with pH > 11 to form a second suspension, and then the second suspension is sprayed onto the blue tungsten suspension, and after heating and drying, doped blue tungsten powder is obtained; The powder making 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 respectively, and then alloy powder A and alloy powder B are mixed evenly to obtain a mixed powder; The hot working is as follows: the alloy rod obtained by cogging is subjected to recrystallization annealing, and then forged by a multi - pass continuous rotary forging device to a tungsten rod with a diameter of 2.5 - 4.0 mm. The tungsten rod is subjected to rough drawing through different - sized wire drawing dies, and the drawing pass reduction ratio of 35% - 60% is repeated multiple times to obtain a tungsten alloy thick wire with a diameter of 0.3 - 0.5 mm; When the tungsten alloy wire is drawn to a diameter of 0.3 - 0.5 mm, annealing treatment is required. The annealing temperature is 1300 - 1700 °C. After annealing, the tungsten alloy wire is cooled in an oxygen environment. The cumulative processing deformation rate after annealing is ≥ 95%. After annealing, drawing is repeated multiple times to obtain tungsten alloy wires with different diameter specifications.

4. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: The preparation method of the blue tungsten powder is as follows: Ammonium paratungstate is fed into a reduction furnace and reduced under the protection of hydrogen and nitrogen at 400 - 600 °C to obtain blue tungsten powder. Among them, the thickness of the ammonium paratungstate powder layer is < 10 mm, the hydrogen flow rate in the reduction furnace is 20 - 40 L / min, the nitrogen flow rate is 80 - 160 L / min, the oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the ammonium tungsten bronze phase composition is > 80%.

5. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: The reduction method of the alloy powder A is as follows: The doped blue tungsten powder is first reduced in a hydrogen reduction furnace at 500 - 800 °C and then reduced again in a hydrogen reduction furnace to obtain alloy powder A with a particle size of 1.5 - 2.6 μm; The reduction method of the alloy powder B is as follows: The doped blue tungsten powder is 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.

6. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: The alloy powder A and the alloy powder B are mixed evenly according to a mass ratio of 1:(1 - 2).

7. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: The sintering is as follows: The pre-sintered blank strip obtained by pressing is subjected to high-temperature sintering at 2200 - 2800 °C.

8. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: In the hot working, the alloy rod obtained by cogging is heated to 2000 - 2600 °C by a medium / high-frequency induction coil for recrystallization annealing.

9. The method for preparing the tungsten alloy wire according to claim 3, characterized in that: The preparation method further includes electrolytic cleaning: The obtained tungsten alloy wire is first electrolyzed by high-concentration alkali solution and alternating current, and then electrolyzed by low-concentration alkali solution and direct current; The obtained tungsten alloy wire is first electrolyzed by a potassium hydroxide solution with a concentration of 20 wt% - 30 wt% and containing 8 - 15 groups of alternating current electrolysis sheets, and then electrolyzed successively by 5 - 8 groups of potassium hydroxide solutions with a concentration of 5 wt% - 10 wt% and containing 5 - 10 groups of direct current electrolysis sheets, and then the surface is cleaned with deionized water, where the electrolysis speed is 50 - 200 m / min.

10. Application of the tungsten alloy wire according to claim 1 or 2 in the fields of cutting, cutting-resistant protection, cables, screen printing, ropes or textiles.

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