Tungsten alloy wire, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of tungsten alloy materials, in particular to a tungsten alloy wire and preparation method therefor and use thereof. The tungsten alloy is composed of the following elements by mass fraction: 0.45 wt% to 0.9wt% of L, 0.05 wt% to 0.2wt% of oxygen, with the balance being tungsten and inevitable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; the wire has a diameter of 20 µm to 60 µm, and in the wire, L or L compounds exist in a linear form along the axial direction of the wire, and the average width D of the L or L compounds along the radial direction is ≤ 5 nm. By controlling the linear doping of L element between the tungsten matrix and making the radial average width of L ≤ 5nm, the crack breakage caused by second phase particles during subsequent pressure processing is greatly reduced, which is conducive to ensuring the mechanical strength of tungsten alloy wire. The wire has a tensile strength of 5000MPa or more at a diameter of 20 µm to 60 µm, and enhances the processing performance of tungsten alloy wire.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of tungsten alloy materials, in particular to a tungsten alloy wire and preparation method therefor and use thereof.BACKGROUND

[0002] Tungsten alloy is an alloy composed of tungsten as the base and other elements added. Among metals, tungsten has the highest melting point, excellent high-temperature strength, creep resistance, thermal conductivity, electrical conductivity and electron emission performance, and a high specific gravity. Besides being widely used in the manufacture of hard alloys and as an alloy additive, tungsten alloys are widely used in aerospace, medical, automotive, electronics and other fields.

[0003] In order to further improve the processing performance of tungsten alloy materials, it is currently possible to reinforce tungsten materials by doping rare earth elements such as lanthanum, cerium, praseodymium, neodymium, etc. into the tungsten matrix. However, rare earth elements act as the second phase in tungsten matrix, and during the processing, they are prone to undergo solid-liquid phase transformation through high-temperature sintering and recrystallization annealing. These second phase particles will merge and grow, causing more cracks at the interface between the second phase particles and tungsten wire. To avoid the occurrence of wire breakage caused by cracks during subsequent processing, 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 of numerous cracks and wire breakage in tungsten alloy wires caused by the introduction of second phases in existing technology, the present invention provides a tungsten alloy wire, the tungsten alloy is composed of the following elements by mass fraction: 0.45 wt% to 0.9wt% of L, 0.05 wt% to 0.2wt% of oxygen, with the balance being tungsten and inevitable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; 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, and so on; and for example, the mass fraction of L is 0.45% to 0.9%, or 0.5% to 0.9%, or 0.7% to 0.9%, or 0.45% to 0.5%, or 0.45% to 0.8%, or 0.45%, 0.5%, 0.55%, 0.6%, 0.7%, 0.8%, 0.85%, and so on; the mass fraction of oxygen is 0.05% to 0.2%, or 0.05% to 0.18%, or 0.1% to 0.2%, or 0.14%, 0.15%, 0.1%, 0.13%, 0.16%, 0.2%, etc.

[0005] The wire has a diameter of 20 µm to 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 not completely uniform, and can also contain several percentage differences, such as 1%, depending on the location; in the wire, L or L compounds exist in a linear form along the axial direction of the wire, and the average width D of the L or L compounds along the radial direction is ≤ 5nm. It should be noted that "linear" refers to the fact that the size of L or L compounds along the axial direction of the wire is much larger than the size along the radial direction of the wire.

[0006] Wherein, the L compounds can be an oxide, such as lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, gadolinium oxide, samarium oxide, and so on. Of course, it can also be other forms of compounds.

[0007] Further, the proportion of tungsten grains in the wire with grain boundary angle less than or equal to 15° is ≥ 50%.

[0008] Further, the average radial width of tungsten grains in the wire is ≤ 80nm.

[0009] Further, when the wire diameter of the wire is > 50 µm and ≤ 60 µm, the average radial width D of the L or L compound is ≤ 5nm, and the tensile strength of the wire is ≥ 5000MPa; when the diameter of the wire is > 40 µm and ≤ 50 µm, the average radial width D of the L or L compound is ≤ 4nm, and the tensile strength of the wire is ≥ 5500MPa; when the diameter of the wire is > 30 µm and ≤ 40 µm, the average radial width D of the L or L compound is ≤ 3nm, and the tensile strength of the wire is ≥6000MPa; and when the wire diameter of the wire is ≥ 20 µm and ≤ 30 µm, the average radial width D of the L or L compound is ≤ 2nm, and the tensile strength of the wire is ≥ 7000MPa.

[0010] The present invention also provides a method for preparing the above-mentioned tungsten alloy wire, wherein the method comprises wet doping, powder preparation, pressing, sintering, cogging, pressure processing, and electrolytic cleaning.

[0011] Further, the wet doping comprises: uniformly dispersing blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly dispersing L nano compound powder in an alkaline solution with pH>11 to form a second suspension, and then spraying the second suspension onto the blue tungsten suspension, heating and drying to obtain doped blue tungsten powder.

[0012] After uniformly dispersing the L nano compound powder in an alkaline solution with a pH >11, and it is stirred at high speed using a stirring device with a speed of 1000 r / min to 2000 r / min; Preferably, the drying method is rapid vacuum heating drying.

[0013] The prepared tungsten alloy powder can have a more uniform dispersion distribution by preparing a compound suspension of L element and directly and uniformly doping fine particles into blue tungsten powder, and using the fine particles as heterogeneous crystal nuclei to crystallize and precipitate together with tungsten particles. This method no longer requires the use of acid salt forms of elements, and it can prepare dispersed particles with a wider range of choices, resulting in more stable and reliable tungsten material properties.

[0014] Further, the method for preparing the blue tungsten powder comprises feeding ammonium paratungstate into a reduction furnace and reducing ammonium paratungstate under the protection of hydrogen and nitrogen at 400°C to 600°C to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer is < 10mm, in the reduction furnace, the hydrogen flow rate is in a range from 20 L / min to 40L / min and the nitrogen flow rate is in a range from 80 L / min to 160L / min and the oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the composition of the ammonium tungsten bronze phase is > 80% of the blue tungsten powder.

[0015] Blue tungsten powder is prepared by using a mixture of hydrogen and nitrogen gas as a reducing protective medium. The properties of the discharged blue tungsten powder are controlled by the thickness of the material layer, the size and flow direction of the hydrogen gas. The oxygen index of blue tungsten is 2.85 ± 0.05, and blue tungsten with an ammonium tungsten bronze phase ratio of over 80% is doped. The blue tungsten particles are coarse and have many surface cracks, which is conducive to the entry of rare earth solution, improves the doping effectiveness, enhances the uniformity of the second phase distribution in the tungsten wire, and improves the comprehensive mechanical and processing properties of the tungsten wire.

[0016] Further, the powder preparation comprises: reducing the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5µm to 2.6 µm and alloy powder B with a particle size of 3.8µm to 4.5 µm, respectively, and then mixing alloy powder A and alloy powder B to obtain a mixed powder; preferably, the reduction method for alloy powder A comprises first reducing the doped blue tungsten powder in a hydrogen reduction furnace at 500°C to 800°C, and then undergo a second reduction in the hydrogen reduction furnace at 700°C to 1100°C to obtain alloy powder A with a particle size of 1.5µm to 2.6µm; preferably, the reduction method for alloy powder B comprisesreducing the doped blue tungsten powder in a hydrogen reduction furnace at 700°C to 1100°C to obtain alloy powder B with a particle size of 3.8µm to 4.5µm; preferably, alloy powder A and alloy powder B are mixed evenly in a mass ratio of 1: (1-2).

[0017] Mixing fine-grained tungsten alloy powder prepared by two reduction processes with coarse-grained tungsten alloy powder prepared by high-temperature one-time reduction in a certain proportion, not only avoids uneven local doping during the reduction process of coarse-grained powder, but also effectively inhibits the aggregation and enrichment of fine-grained powder after reduction, which prevents the microstructural inhomogeneity of the alloy powder from causing defects in the subsequent pressure working process and reduces the risk of wire breakage.

[0018] Further, the sintering specifically comprises: sintering the pre-sintered billet obtained by pressing at a high temperature of 2200°C to 2800°C.

[0019] Further, the pressure processing comprises subjecting the alloy rod obtained by the cogging recrystallization annealing, and then swaging to a tungsten rod with a diameter of 2.5 mm to 4.0 mm through multiple passes of continuous swaging apparatus, subjecting the tungsten rod to redrawing processing through different specifications of drawing dies, and repeating redrawing processing multiple times, with a reduction ratio of 35% to 60%, to obtain tungsten alloy coarse wire with a diameter of 0.3mm to 0.5mm.

[0020] Tungsten alloy wire is processed using a high reduction ratio of 35% to 60%. The obtained wire fibers have a more developed fibrous structure, which is conducive to the linearization of L elements and the compounds thereof during the processing, thereby improving the breaking force of the wire.

[0021] Further, in the pressure processing, the alloy rod obtained by the cogging is heated to 2000°C to 2600°C by a medium / high-frequency induction coil for recrystallization annealing.

[0022] Further, the tungsten alloy wire needs to be annealed when drawn to a diameter of 0.3 mm to 0.5mm, with an annealing temperature of 1300°C to 1700 °C, after annealing, the tungsten alloy wire is cooled in an oxygen environment, and the cumulative processing deformation rate after annealing is ≥ 95%, after annealing, the drawing process is repeated multiple times to obtain tungsten alloy wires with different diameter specifications. When the tungsten alloy wire is drawn to 0.3mm or less, no further annealing treatment is required.

[0023] By annealing and oxygen cooling the wire, the content and thickness of the oxide layer on the surface of tungsten alloy wire can be increased, which can effectively improve the lubrication layer of the wire, thereby improving the drawing conditions, ensuring the feasibility of high reduction ratio drawing of the wire, and significantly reducing the probability of wire breakage.

[0024] The wire after annealing and cooling is drawn using different specifications of drawing dies, and repeated drawing is carried out multiple times to reach the desired wire diameter.

[0025] Further, the electrolytic cleaning comprises: the prepared tungsten alloy wire is first subjected to high concentration alkaline solution and AC electrolysis, and then subjected to low concentration alkaline solution and DC electrolysis; preferably, the tungsten alloy wire produced is first electrolyzed using a potassium hydroxide solution containing 8 to 15 sets of AC electrolytic cells at a concentration of 20wt% to 30wt%, and then sequentially electrolyzed using 5-8 sets of potassium hydroxide solutions containing 5 to 10 sets of DC electrolytic cells at a concentration of 5wt% to 10wt%, the surface is then cleaned with deionized water at an electrolysis rate of 50 m / min to 200m / min.

[0026] The surface layer of the black tungsten wire is peeled off first by using high-concentration alkaline solution and AC electrolysis, which can quickly remove the surface graphite layer and tungsten oxide layer, and effectively eliminate the grooves on the wire surface at the same time. Then, the tungsten wire is electrolytic polished successively through low-concentration alkaline solution and direct current pulse mode. The obtained wire has better uniformity in diameter, which can effectively ensure the diameter tolerance of the wire material within ±1% of the diameter.

[0027] The present invention further provides use of the above-mentioned tungsten alloy wire in the fields of cutting, cutting-resistant protection, cables, screen printing, ropes, or textiles.

[0028] Compared with the prior art, the tungsten alloy wire provided by the present invention has the following advantages: One or more rare earth elements / rare earth compounds are used as the second phase strengthening tungsten material in the present invention. By controlling the doping of L or L compounds in a linear fashion into the tungsten matrix, and making the average width of L or L compounds along the radial direction ≤ 5nm, the cracking and wire breakage caused by second phase particles during subsequent pressure processing are greatly reduced, which is conducive to ensuring the mechanical strength of tungsten alloy wire, enabling the wire to achieve a tensile strength of 5000MPa or more at a wire diameter of 20 µm to 60 µm, while also enhancing the processing performance of tungsten alloy wire.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly describe specific implementations of the present application or technical solutions in the prior art, the accompanying drawings needed by the description in the specific implementations or in the prior art will be briefly introduced below. Apparently, the accompanying drawings in the following description are some implementations of the present application. Those ordinarily skilled in the art may also obtain other accompanying drawings according to these accompanying drawings without making creative work.

[0030] FIG. 1 is a schematic diagram of the method for measuring the average radial width of L or L compounds provided by the present invention.DETAILED DESCRIPTION

[0031] In order to clarify the object, technical solution, and advantages of the examples of the present invention, the following will provide a clear and complete description of the technical solution in the examples of the present invention in conjunction with the accompanying drawings. Obviously, the described examples are a part of the examples of the present invention, not all of them. Based on the examples of the present invention, all other examples obtained by ordinary skilled persons in the art without creative work are within the scope of protection of the present invention.

[0032] The present invention provides a tungsten alloy wire, wherein the tungsten alloy is composed of the following elements by mass fraction: 0.45 wt% to 0.9wt% of L, 0.05 wt% to 0.2wt% of oxygen, with the balance being tungsten and inevitable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; it can be understood that inevitable impurities are other elements introduced during the preparation process.

[0033] The wire has a diameter of 20 µm to 60 µm, and in the wire, L or L compounds exist in a linear form along the axial direction of the wire, and the average width D of the L or L compounds along the radial direction is ≤ 5nm.

[0034] The proportion of tungsten grains in the wire with grain boundary angle less than or equal to 15° is ≥ 50%; the average radial width of tungsten grains in the wire is ≤ 80nm; When the wire diameter of the wire is > 50 µm and ≤ 60 µm, the average radial width D of the L or L compound is ≤ 5nm, and the tensile strength of the wire is ≥ 5000MPa; when the diameter of the wire is > 40 µm and ≤ 50 µm, the average radial width D of the L or L compound is ≤ 4nm, and the tensile strength of the wire is ≥ 5500MPa; when the diameter of the wire is > 30 µm and ≤ 40 µm, the average radial width D of the L or L compound is ≤ 3nm, and the tensile strength of the wire is ≥6000MPa; and when the wire diameter of the wire is ≥ 20 µm and ≤ 30 µm, the average radial width D of the L or L compound is ≤ 2nm, and the tensile strength of the wire is ≥ 7000MPa.

[0035] The present invention provides a method for preparing the tungsten alloy wire comprising wet doping, powder preparation, pressing, sintering, cogging, pressure processing, and electrolytic cleaning.

[0036] The wet doping comprises: uniformly dispersing blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly dispersing L nano compound powder in an alkaline solution with pH>11 to form a second suspension, and then spraying the second suspension onto the blue tungsten suspension, heating and drying to obtain doped blue tungsten powder; the method for preparing the blue tungsten powder comprises feeding ammonium paratungstate into a reduction furnace and reducing ammonium paratungstate under the protection of hydrogen and nitrogen at 400°C to 600°C to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer is < 10mm, in the reduction furnace, the hydrogen flow rate is in a range from 20 L / min to 40L / min and the nitrogen flow rate is in a range from 80 L / min to 160L / min and the oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the composition of the ammonium tungsten bronze phase is > 80% of the blue tungsten powder. the powder preparation comprises: first reduce the doped blue tungsten powder in a hydrogen reduction furnace at 500°C to 800°C, and then undergo a second reduction in the hydrogen reduction furnace at 700°C to 1000°C to obtain alloy powder A with a particle size of 1.5µm to 2.6µm; the doped blue tungsten powder is reduced in a hydrogen reduction furnace at 700°C to 1100°C to obtain alloy powder B with a particle size of 3.8µm to 4.5µm; alloy powder A and alloy powder B are mixed evenly in a mass ratio of 1: (1-2); the sintering comprises: sintering the pre-sintered billet obtained by pressing at a high temperature of 2200°C to 2800°C to obtain a sintered billet with a density of 18.6g / cm 3< or higher; preferably, sintering is performed in a hydrogen atmosphere, where the hydrogen purity is > 99.5%; wherein the pressure processing comprises the alloy rod obtained by the cogging is heated to 2000°C to 2600°C by a medium / high-frequency induction coil for recrystallization annealing, and then swaged to a tungsten rod with a diameter of 2.5 mm to 4.0 mm through multiple passes of continuous swaging apparatus; the tungsten rod is subjected to redrawing processing through different specifications of drawing dies, and the reduction ratio of the drawing passes is repeated multiple times, with a reduction ratio of 35% to 60%, to obtain tungsten alloy coarse wire with a diameter of 0.3mm to 0.5mm; the tungsten alloy wire needs to be annealed when drawn to a diameter of 0.3 mm to 0.5mm, with an annealing temperature of 1300°C to 1700 °C, after annealing, the tungsten alloy wire is cooled in an oxygen environment, and the cumulative processing deformation rate after annealing is ≥ 95%.

[0037] The wire after annealing and cooling is drawn using different specifications of drawing dies, and repeated drawing is carried out multiple times to reach the desired wire diameter.

[0038] In addition, the pressing and cogging steps in the above steps are preferred but not limited to the following implementation methods, namely: pressing: the mixed powder is pressed into a compact with a single weight of 1.5 kg to 6 kg using isostatic pressing at a pressure of 140 MPa to 240MPa, and the compact is pre-sintered at 1200°C to 1400°C for 10 minutes to 30 minutes in a hydrogen atmosphere to increase the strength of the compact; cogging: a multi roll rolling mill is used to continuously roll sintered billets with a diameter of 15 mm to 25 mm into 8.0 mm to 12.0 mm alloy rods at 1600°C to 1700°C.

[0039] The method further comprises electrolytic cleaning: the tungsten alloy wire produced is first electrolyzed using a potassium hydroxide solution containing 8 to 15 sets of AC electrolytic cells at a concentration of 20wt% to 30wt%, and then sequentially electrolyzed using 5 to 8 sets of potassium hydroxide solutions containing 5 to 10 sets of DC electrolytic cells at a concentration of 5wt% to 10wt%, the surface is then cleaned with deionized water at an electrolysis rate of 50 m / min to 200m / min.

[0040] Therefore, the present invention provides the following examples and comparative examples of tungsten alloy element compositions, as shown in Table 1: Table 1 (Unit wt%) :Elemental compositionExample 1.1Example 1.2Example 1.3Example 1.4Example 1.5Example 1.6L Elementlanthanum-0.45-0.35--cerium0.6-----praseodymium---0.40.4-neodymium--0.75---gadolinium----0.350.4samarium-----0.35oxygen0.1370.0780.1250.130.1150.172 Elemental compositionComparative Example 2.1Comparative Example 2.2Comparative Example 2.3L Elementlanthanum-0.52-cerium0.920.40.43praseodymium---neodymium---gadolinium---samarium---oxygen0.210.1810.098

[0041] Wherein, "-" indicates that the corresponding element has not been added.Example 1.1

[0042] This example is to prepare a tungsten alloy wire according to the present invention. By mass fraction, the elemental components of the material comprise: 0.6wt% of cerium, 0.137wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0043] The preparation steps are as follows: Step 1: blue tungsten preparation: ammonium paratungstate powder was subjected to hydrogen reduction in reverse hydrogen continuous reduction furnaces at 400 °C, 450 °C, 500 °C, and 560 °C. The thickness of the ammonium paratungstate powder layer was 8mm, the hydrogen flow rate was 30L / min, and the nitrogen flow rate was 140L / min. Blue tungsten powder was obtained, with an oxygen index of 2.87 and an ammonium tungsten bronze phase fraction of 82%. Step 2: wet doping: the blue tungsten powder obtained in step 1 was uniformly dispersed in deionized water to obtain a blue tungsten suspension, in which the volume ratio of blue tungsten powder to deionized water was 1:15. An appropriate amount of cerium oxide nano powder was uniformly dispersed in a sodium hydroxide solution with a pH of 13, and then stirred at a high speed of 1500r / min in a high-speed emulsifying equipment to form a second suspension. Then, the second suspension was sprayed into the blue tungsten suspension through a vacuum pipeline. After the spraying was completed, rapid vacuum heating and drying were performed to obtain doped blue tungsten powder. Step 3: powder preparation: the doped blue tungsten powder obtained in step 2 was first reduced in a three-temperature zone hydrogen reduction furnace at 500°C, 650°C, and 750°C, and then second reduced in a four-temperature zone hydrogen reduction furnace at 700°C, 810°C, 870°C, and 920°C to obtain alloy powder A with a particle size of 2.0µm.

[0044] The doped blue tungsten powder obtained in step 2 was reduced in a four-temperature 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. 1µm; alloy powder A and alloy powder B were placed in the high-energy powder mixer at a mass ratio of 1:1.5, and the powder was mixed for 120 minutes. The mixed powder was obtained evenly, and the particle size of the mixed powder was 3.0µm.

[0045] Step 4: pressing: the mixed powder obtained in step 3 was pressed into a 3kg compact by isostatic pressing under a pressure of 160MPa. The compact was then pre-sintered for 20 minutes in a hydrogen atmosphere at 1300°C to obtain pre-sintered billet.

[0046] Step 5: sintering: the pre-sintered billets obtained in step 4 were subjected to high-temperature sintering at 2600°C to obtain sintered billets with a density of 18.68g / cm 3< .

[0047] Step 6: cogging: the sintered billets with a diameter of 20mm were continuously rolled into 8.0mm alloy rods by using a multi-roll mill at a heating temperature of 1600°C.

[0048] Step 7: pressure processing: the alloy rod obtained in step 6 was heated to 2400°C through a high-frequency induction coil for recrystallization annealing, and then swaged through a multi-pass continuous rotary swaging equipment to a tungsten rod with a diameter of 3.0mm.

[0049] Step 8: tungsten rods were subjected to redrawing processing through different specifications of drawing dies. The drawing passes were repeated with a reduction ratio of 35% to 60% to obtain tungsten alloy thick wire materials with a diameter specification of 0.4mm.

[0050] Step 9: annealing: the tungsten alloy thick wire obtained in step 8 was subjected to annealing treatment. After annealing, the tungsten alloy wire was cooled in an oxygen environment, with the annealing temperature being 1650°C, and the mass percentage of surface oxides on the wire was 1.18%.

[0051] Step 10: the annealed wire obtained in step 9 was drawn through wire different specifications of drawing dies. The drawing process was repeated multiple times until the diameters are 60µm, 48µm, 38µm, 28µm, and 20µm respectively.

[0052] Step 11: electrolytic cleaning: the tungsten alloy wire obtained in step 10 was first electrolyzed through a potassium hydroxide solution with a concentration of 22wt%, which included 12 groups of AC electrolytic cells. Then, it was electrolyzed successively through 6 groups of potassium hydroxide solution with a concentration of 6wt%, which included 5 groups of DC electrolytic cells. The electrolysis speed was 180m / min. After electrolysis, the surface was cleaned with deionized water to obtain white fine tungsten wires with different diameters.Example 1.2

[0053] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.45wt% of lanthanum, 0.078wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0054] The preparation steps are the same as Example 1.1 except that cerium oxide is replaced with lanthanum oxide in Step 2.Example 1.3

[0055] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.75wt% of neodymium, 0.125wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0056] The preparation steps are the same as in Example 1.1, except that cerium oxide is replaced with neodymium oxide in Step 2.Example 1.4

[0057] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.35wt% of lanthanum, 0.4wt% of praseodymium, 0.13wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0058] The preparation steps are the same as in Example 1.1, except that cerium oxide is replaced with lanthanum oxide and praseodymium oxide in Step 2.Example 1.5

[0059] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.35wt% of gadolinium, 0.4wt% of praseodymium, 0.115wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0060] The preparation steps are the same as in Example 1.1, except that cerium oxide is replaced with gadolinium oxide and praseodymium oxide in Step 2.Example 1.6

[0061] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.35wt% of samarium, 0.4wt% of gadolinium, 0.172wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0062] The preparation steps are the same as in Example 1.1, except that cerium oxide is replaced with samarium oxide and gadolinium oxide in Step 2.Example 1.7

[0063] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition is the same as in Example 1.1 The difference between the preparation steps and Example 1.1 is that in step 3, alloy powder A and alloy powder B are mixed in a ratio of 1:4 during powder production. The remaining preparation steps are the same as in Example 1.1.Comparative Example 2.1

[0064] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.92wt% of cerium, 0.21wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0065] The preparation steps are the same as in Example 1.1.Comparative Example 2.2

[0066] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.4wt% of cerium, 0.52wt% of lanthanum, 0.181wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0067] The preparation steps are the same as in Example 1.1, except that the second suspension in Step 2 also comprises lanthanum oxide.Comparative Example 2.3

[0068] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition comprises the following elements by mass fraction: 0.43wt% of cerium, 0.098wt% of oxygen, and the balance is tungsten and inevitable impurities.

[0069] The preparation steps are the same as in Example 1.1.Comparative Example 2.4

[0070] This example is to prepare a tungsten alloy wire according to the present invention. The material element composition is the same as in Example 1.1. The difference between the preparation steps and Example 1.1 is that: Step 8: the tungsten rod was subjected to redrawing processing through different specifications of drawing dies, and the reduction ratio of 35% to 60% was repeated multiple times to obtain a 0.2mm diameter tungsten alloy coarse wire; Step 9: annealing: the tungsten alloy coarse wire obtained in Step 8 was subjected to annealing treatment. After annealing, the tungsten alloy wire was cooled in an oxygen environment, with an annealing temperature of 1650°C and a surface oxide mass percentage of 1.35%;

[0071] The remaining steps are the same as in Example 1.1.Comparative Example 2.5

[0072] This example is to prepare a tungsten alloy wire according to the present invention, with the same material element composition as in Example 1.1. The difference between the preparation steps and Example 1.1 is that in step 8. The tungsten rod was drawn through different specifications of drawing dies, and the reduction ratio of 10% to 30% was repeated multiple times to obtain a 0.4mm diameter tungsten alloy coarse wire.

[0073] The remaining steps are the same as in Example 1.1.Comparative Example 2.6

[0074] This example is to prepare a tungsten alloy wire according to the present invention, with the same material element composition as in Example 1.1. The difference between the preparation steps and Example 1.1 is that Step 2, wet doping: the blue tungsten powder obtained in Step 1 was uniformly dispersed in deionized water to obtain a blue tungsten suspension, where the volume ratio of blue tungsten powder to deionized water was 1:15. An appropriate amount of cerium oxide nano powder was dissolved in deionized water and added to the blue tungsten suspension for thorough stirring and drying to obtain doped blue tungsten, with a stirring speed of 40r / min and a drying temperature of 160 °C.

[0075] The remaining steps are the same as in Example 1.1.Performance testing

[0076] The tensile strength of the wires obtained from Examples 1.1-1.7 and Comparative Examples 2.1-2.3 was tested, and the average diameter of tungsten grains and the average width of L or L compounds along the radial direction were measured. The test results were shown in Table 2. The tensile strength testing method were as follows: using a standard tensile machine, a 200mm long tungsten wire was clamped, and one end was loaded at a constant speed to obtain the tensile force data;

[0077] The tensile strength was calculated using the following formula: σ = F / S , wherein F is the tensile force, N; S is the original cross-sectional area, mm.

[0078] The method for measuring the average radial width of tungsten grains were as follows: a focused ion beam cutting device was used to cut thin slices along the axial direction of the material, and the thin slices were placed in a scanning electron microscope with a backscatter diffractometer (EBSD) to collect the morphology of the tungsten grains in the test sample. The width of the upper grain boundary and lower grain boundary was measured using conventional measurement software to obtain the radial width of the tungsten grains. The average of the diameters of multiple tungsten grains measured was obtained as the average radial width of the tungsten grains.

[0079] The method for measuring the average width of L or L compounds along the radial direction is shown in FIG. 3. A focused ion beam cutting device is used to cut thin slices along the axial direction of tungsten alloy wire 1. The thin slices are placed in a high-resolution transmission electron microscope, and the morphology is first observed using a bright and dark field mode. Positions with obvious contrast in the morphology are selected for line scanning, and line scanning is performed perpendicular to the axial position of the tungsten alloy wire to obtain information on element distribution and composition. The positions with obvious contrast and element distribution in the sample (i.e., the positions where the elements of the second phase are concentrated) are detected by transmission electron microscopy to obtain high-resolution images of the second phase. Fourier transform is performed on the high-resolution images to obtain lattice diffraction spectra. Using the obtained second phase diffraction spectrum, combined with the composition information of the second phase elements, the corresponding phases of each diffraction spectrum are calibrated. By comparing the phase identification cards, after confirming that this location is the phase structure of L or L compounds, and the width of the L or L compound are measured by software. In FIG. 3, 10 represents the tungsten matrix, and 20 represents L or L compounds. By measuring the width of multiple L separately and calculating the average value, the radial average width of L or L compounds is obtained. It can be understood that for ease of explanation, FIG. 3 is a partial cross-section of the tungsten alloy wire thin slice, not the entire thin slice. Table 2SampleWire diameter µmTensile strength MPaRadial average width of tungsten grains nmL radial average width nmExample 1.1605485724.1485793683.6386501602.2287487481.5207880360.9Example 1.2605153783.3485580732.8386020661.9287060561.1207450460.7Example 1.3605660703.5485820632.9386690592.4287660481.3208120310.5Example 1.4605710622.3485990551.7386730421.3287730360.8208280290.3Example 1.5605680592.2485960521.8386690391.2287695350.9207990300.6Example 1.6605670652.5485950561.9386680441.5287650391.1207920320.8Example 1.7605330764.8485660704.0386330552.6287290491.8207660411.1Comparative Example 2.1605750507.248 / / / 38 / / / 28 / / / 20 / / / Comparative Example 2.2605750496.148 / / / 38 / / / 28 / / / 20 / / / Comparative Example 2.3604985964485420923.2385910842.3286230812.0206580731.6Comparative Example 2.6605020983.3485560922.7385820862.3286120831.8206450751.4

[0080] " / " indicates that there is no corresponding data.

[0081] From Table 2, it can be seen that the tungsten alloy wire provided in the examples of the present invention has a tensile strength of 5000 MPa or more at a wire diameter of 20 µm to 60 µm, and its tensile strength increases as the wire diameter decreases. At 28 µm, its tensile strength can reach 7000 MPa or more; Moreover, the tungsten alloy wire provided in the examples of the present invention contains L or L compounds in a linear form, with an average radial width of less than 5 nm and the average width of tungsten grains along the radial direction is less than 80 nm

[0082] 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 0.9wt%, there are too many second phases in the tungsten alloy wire, 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, leading to an increase in the difficulty of processing the tungsten alloy wire, which cannot be processed to 60 µm or less; When the L content in tungsten alloy wire is less than 0.45wt%, the strengthening effect of the second phase on tungsten alloy wire is not significant, resulting in a decrease in tensile strength.

[0083] From the comparison of Comparative Example 2.6 and Example 1.1, it can be seen that the doping method of the present patent results in a smaller average radial width of tungsten grains in the wire, and the second phase particle size is also more slender. This is because this patent uses dispersed nano powder particles to enter the tungsten powder during the early doping process, resulting in better dispersion uniformity. At the same time, due to the presence of more second phase particles inside the tungsten grains after particle reduction, the refinement effect of tungsten grains is better, and the small second phase particles can better hinder the deformation of tungsten grains, thereby improving the overall tensile strength of the tungsten wire.

[0084] The tensile strength of the wire obtained from Example 1.1 and Comparative Examples 2.4 and 2.5 is tested, and the proportion of boundary angles is measured to calculate the cumulative processing deformation rate of the wire. The test results are shown in Table 3.

[0085] The measurement method for the proportion of boundary angle is as follows: a focused ion beam cutting device is used to cut thin slices along the axis of tungsten alloy wire, and the thin slices are placed in a scanning electron microscope with Electron Backscattered Diffraction (EBSD) to collect the orientation difference information between the tungsten grains of the sample to be tested and the surrounding tungsten grains. The proportion of grain boundaries with an angle difference of ≤ 15 ° is measured.

[0086] The formula for the cumulative deformation rate of wire processing is: 1-D1 * D1 / (D2 * D2);

[0087] D1 is the wire diameter of the finished wire, and D2 is the wire diameter during annealing treatment. Table 3SampleWire diameter µmProportion % of boundary angle ≤15°Tensile strength MPaCumulative deformation rate of wire processing %Example 1.15853548597.894857579398.563861650199.092864748799.51Comparative Example 2.45839499091.594843526094.243846575096.392849602098.04Comparative Example 2.55835508097.894838539598.56 / / / / / / / /

[0088] " / " indicates that there is no corresponding data.

[0089] From the comparison of 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 0.3mm, the proportion of tungsten boundary angle less than or equal to 15° in the resulting product is small, resulting in more cracks and broken lines caused by second phase particles during subsequent pressure processing, which in turn affects the tensile strength.

[0090] From the comparison results of Comparative Example 2.5 and Example 1.1, it can be seen that when the conventional drawing pass reduction ratio of 10% to 30% is used in the pressure processing step, the average width of L in the produced wire of various specifications is larger, and the proportion of tungsten boundary angle less than or equal to 15° is smaller, resulting in more cracks and wire breaks caused by second phase particles in the subsequent pressure processing process, which affects the tensile strength and cannot be processed 40 microns or less. By using a high reduction ratio of 35% to 60% for tungsten alloy wire processing, the obtained wire fibers are more developed, which is conducive to the fibrosis of L elements and their compounds during the processing. The deformation degree of tungsten grain boundaries is faster, thereby improving the tensile strength of the wire. At the same time, by setting the annealing point and increasing the cumulative deformation after high-temperature annealing, as well as improving the degree of deformation of the wire, the proportion of small angle tungsten grain boundaries can be further increased to enhance the tensile strength of the tungsten wire.

[0091] Finally, it should be noted that the above examples are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the aforementioned examples, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or equivalently replace some or all of the technical features; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the scope of the various embodiments of the present invention.

Claims

1. A tungsten alloy wire, characterized in that the tungsten alloy is composed of the following elements by mass fraction: 0.45 wt% to 0.9wt% of L, 0.05 wt% to 0.2wt% of oxygen, with the balance being tungsten and inevitable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; the wire has a diameter of 20 µm to 60 µm, and in the wire, L or L compounds exist in a linear form along the axial direction of the wire, and the average width D of the L or L compounds along the radial direction is ≤ 5 nm.

2. The tungsten alloy wire according to claim 1, characterized in that the proportion of tungsten grains in the wire with grain boundary angle less than or equal to 15° is ≥ 50%; preferably, the average radial width of tungsten grains in the wire is ≤ 80 nm; preferably, when the wire diameter of the wire is > 50 µm and ≤ 60 µm, the average radial width D of the L or L compound is ≤ 5nm, and the tensile strength of the wire is ≥ 5000 MPa; when the diameter of the wire is > 40 µm and ≤ 50 µm, the average radial width D of the L or L compound is ≤ 4nm, and the tensile strength of the wire is ≥ 5500MPa; when the diameter of the wire is > 30 µm and ≤ 40 µm, the average radial width D of the L or L compound is ≤ 3nm, and the tensile strength of the wire is ≥6000MPa; and when the wire diameter of the wire is ≥ 20 µm and ≤ 30 µm, the average radial width D of the L or L compound is ≤ 2nm, and the tensile strength of the wire is ≥ 7000MPa.

3. A method for preparing the tungsten alloy wire according to claim 1 or 2, characterized in that the method comprises wet doping, powder preparation, pressing, sintering, cogging, pressure processing, and electrolytic cleaning.

4. The method for preparing the tungsten alloy wire according to claim 3, characterized in that the wet doping comprises uniformly dispersing blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly dispersing L nano compound powder in an alkaline solution with pH>11 to form a second suspension, and then spraying the second suspension onto the blue tungsten suspension, heating and drying to obtain doped blue tungsten powder; preferably, the method for preparing the blue tungsten powder comprises feeding ammonium paratungstate into a reduction furnace and reducing ammonium paratungstate under the protection of hydrogen and nitrogen at 400°C to 600°C to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer is < 10 mm, in the reduction furnace, the hydrogen flow rate is in a range from 20 L / min to 40L / min and the nitrogen flow rate is in a range from 80 L / min to 160 L / min, and the oxygen index of the blue tungsten powder is 2.85 ± 0.05, and the composition of the ammonium tungsten bronze phase is > 80% of the blue tungsten powder.

5. The method for preparing the tungsten alloy wire according to claim 3, <b>characterized in that the powder preparation comprises reducing the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5 µm to 2.6 µm and alloy powder B with a particle size of 3.8 µm to 4.5 µm, respectively, and then mixing alloy powder A and alloy powder B to obtain a mixed powder; preferably, the reduction method for alloy powder A comprises first reducing the doped blue tungsten powder in a hydrogen reduction furnace at 500°C to 800°C, and then undergoing a second reduction in the hydrogen reduction furnace to obtain alloy powder A with a particle size of 1.5µm to 2.6µm; preferably, the reduction method for alloy powder B comprises reducing the doped blue tungsten powder in a hydrogen reduction furnace at 700°C to 1100°C to obtain alloy powder B with a particle size of 3.8 µm to 4.5 µm; preferably, alloy powder A and alloy powder B are mixed evenly in a mass ratio of 1: (1-2).

6. The method for preparing the tungsten alloy wire according to claim 3, characterized in that the sintering comprises sintering the presintered billet obtained by pressing at a high temperature of 2200°C to 2800°C.

7. The method for preparing the tungsten alloy wire according to claim 3, characterized in that the pressure processing comprises subjecting the alloy rod obtained by the cogging to recrystallization annealing, and then swaging to a tungsten rod with a diameter of 2.5 mm to 4.0 mm through multiple passes of continuous swaging apparatus, subjecting the tungsten rod to redrawing processing through different specifications of drawing dies, and repeating redrawing processing multiple times, with a reduction ratio of 35% to 60%, to obtain tungsten alloy coarse wire with a diameter of 0.3 mm to 0.5mm; preferably, in the pressure processing, the alloy rod obtained by the cogging is heated to 2000°C to 2600°C by a medium / high-frequency induction coil for recrystallization annealing.

8. The method for preparing the tungsten alloy wire according to claim 3, characterized in that the tungsten alloy wire needs to be annealed when drawn to a diameter of 0.3 mm to 0.5 mm, with an annealing temperature of 1300°C to 1700 °C, after annealing, the tungsten alloy wire is cooled in an oxygen environment, and the cumulative processing deformation rate after annealing is ≥ 95%, after annealing, the drawing process is repeated multiple times to obtain tungsten alloy wires with different diameter specifications.

9. The method for preparing the tungsten alloy wire according to claim 3, <b>characterized in that the method further comprises electrolytic cleaning: the prepared tungsten alloy wire is first subjected to high concentration alkaline solution and AC electrolysis, and then subjected to low concentration alkaline solution and DC electrolysis; preferably, the tungsten alloy wire produced is first electrolyzed using a potassium hydroxide solution containing 8 to 15 sets of AC electrolytic cells at a concentration of 20 wt% to 30 wt%, and then sequentially electrolyzed using 5-8 sets of potassium hydroxide solutions containing 5 to 10 sets of DC electrolytic cells at a concentration of 5 wt% to 10wt%, the surface is then cleaned with deionized water at an electrolysis rate of 50 m / min to 200m / min.

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

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