High-toughness rare earth tungsten alloy with coherent interface and preparation method and application thereof

Abstract

The application discloses a high-strength and high-toughness rare earth tungsten alloy with a coherent interface and a preparation method and application thereof. The tungsten alloy is mainly composed of tungsten and a rare earth compound. The preparation of the tungsten alloy is through in-situ reaction of the rare earth compound and the tungsten matrix in a sintering process. On one hand, a coherent phase interface with high strength and high toughness is obtained. On the other hand, the harmful element-oxygen adsorbed at the grain boundary and solid-solved in the body is taken away by a high-activity element, and the grain boundary interface bonding capacity is improved. Finally, based on the double optimization of the phase interface and the grain boundary, the tensile strength and the processability of the rare earth tungsten alloy are greatly improved. Through subsequent processing, an ultra-high-strength alloy thin wire can be obtained, and the yield rate is more than 90% during the processing process.

Description

Technical Field

[0001] This invention relates to the field of tungsten alloy materials technology, specifically to a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface, its preparation method, and its application. Background Technology

[0002] Materials known to possess high strength and hardness include high-carbon steel and tungsten. However, the tensile strength of existing high-carbon steel wires is generally below 5000 MPa, while their diameter is greater than 37 μm, reaching the processing limit and making it impossible to process them into finer diameters. With the rapid development of the photovoltaic industry, the trend towards larger and thinner silicon wafers is emerging. The efficient cutting of silicon material urgently requires diamond wire with higher strength and smaller diameter, and the main body of the wire is the core carrier, which traditional high-carbon steel wire can no longer meet. Although some companies have developed ultrafine tungsten wires with different diameters (CN 114250395 A, CN 114231813 A, CN 114250395 A, CN113186438 A, CN 113234980 A, CN 114250395 A, CN 114231813 A, CN 113215463 A, CN114211049 A), their tensile strength remains low. Furthermore, because most of these wires utilize rare-earth second-phase reinforcement, the uneven distribution of the second phase or significant phase difference with the matrix leads to frequent wire breakage during production or use. This is especially true when the wire diameter is further refined to below 30 μm, where the deformation strengthening effect begins to significantly diminish, resulting in an inability to effectively improve tensile strength. Therefore, there is an urgent need to develop a method for preparing novel high-strength and high-toughness tungsten alloys to further improve tensile strength and reduce wire breakage rates. Summary of the Invention

[0003] In view of the above-mentioned shortcomings, the present invention provides a high-strength and high-toughness rare earth tungsten alloy with a coherent interface, its preparation method and application. The tungsten alloy of the present invention is mainly composed of metallic tungsten and contains rare earth compounds and tungsten compounds with a coherent interface generated in situ, which can solve the problems of low strength and high wire breakage rate of tungsten alloy busbars in the prior art.

[0004] To achieve the above objectives, the present invention provides a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface, wherein the tungsten alloy comprises tungsten and a rare-earth compound; the rare-earth element in the rare-earth compound is any one or more of neodymium, yttrium, europium, lanthanum, cerium, and scandium; and the rare-earth compound is a boride, carbonyl compound, acetate, or acetone salt of a rare-earth element.

[0005] According to one aspect of the invention, the amount of rare earth compound added is 0.01 wt% to 5 wt%.

[0006] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned high-strength and high-toughness rare earth tungsten alloy with a coherent interface, which includes doping, powdering, pressing and sintering in sequence.

[0007] According to one aspect of the present invention, the sintering includes low-temperature sintering and high-temperature sintering; the temperature of the low-temperature sintering is 600-1100°C; and the temperature of the high-temperature sintering is 1200-2800°C.

[0008] According to one aspect of the present invention, the low-temperature sintering is carried out in a hydrogen atmosphere, first at 800°C for 1 hour, and then at 1100°C for 1 hour.

[0009] According to one aspect of the present invention, the high-temperature sintering is performed by holding at 1200-2300°C for 4 hours in a hydrogen atmosphere.

[0010] According to one aspect of the invention, the doping is achieved by uniformly mixing a tungsten source and a rare earth compound through solid-phase doping or spray drying; the tungsten source includes one or more of tungsten powder, tungsten oxide, and ammonium tungstate.

[0011] Based on the same inventive concept, the present invention also provides the application of the above-mentioned high-strength and high-toughness rare-earth tungsten alloy with coherent interface or the high-strength and high-toughness rare-earth tungsten alloy with coherent interface prepared by the above-mentioned preparation method, wherein the tungsten alloy is applied to tungsten alloy wire.

[0012] According to one aspect of the present invention, the diameter of the tungsten alloy wire is 37 μm or less; when the diameter of the tungsten alloy wire is 30 μm, the tensile strength of the tungsten alloy wire is 7200 MPa.

[0013] According to one aspect of the invention, the yield of the tungsten alloy wire exceeds 90%.

[0014] The beneficial effects of this invention are:

[0015] The tungsten alloy of this application is based on tungsten and includes tungsten and rare earth compounds. This invention utilizes the in-situ reaction between rare earth compounds and the tungsten matrix during sintering. This in-situ reaction achieves a high-strength and tough coherent phase interface on one hand, and on the other hand, removes harmful elements—oxygen—adsorbed at grain boundaries and dissolved in the bulk through highly reactive elements, thereby improving interfacial bonding. Ultimately, based on the dual optimization of phase boundaries and grain boundaries, the tensile strength and machinability of the rare earth tungsten alloy are significantly improved. Through subsequent processing, ultra-high strength alloy wires can be obtained with almost no wire breakage during processing, and the yield exceeds 90%. The obtained tungsten alloy wire has a diameter of less than 37 μm and a tensile strength exceeding 7200 MPa (30 μm). Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the coherent interface of the tungsten-lanthanum alloy described in Embodiment 1 of the present invention. Detailed Implementation

[0017] To make the present invention easier to understand, specific embodiments are described below to further illustrate the invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved herein can be purchased commercially or obtained by known methods.

[0018] To address the problems of low strength and high wire breakage rate of tungsten alloy busbars in the prior art, this invention provides a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface. The tungsten alloy comprises tungsten and rare-earth compounds; the rare-earth elements in the rare-earth compounds are any one or more of neodymium, yttrium, europium, lanthanum, cerium, and scandium; and the rare-earth compounds are borides, carbonyl compounds, acetates, or acetone salts of rare-earth elements.

[0019] Preferably, the amount of rare earth compound added is 0.01 wt% to 5 wt%.

[0020] Preferably, the tungsten alloy further includes a portion (small amount) of solid solution strengthening metal elements, including any one or more of molybdenum, iron, cobalt, vanadium, rhenium, titanium, and zirconium. It should be noted that the solid solution strengthening metal elements can further optimize the performance of this application (e.g., fineness, strength, and toughness).

[0021] Preferably, the present invention also provides a method for preparing the above-mentioned high-strength and high-toughness rare earth tungsten alloy with a coherent interface, which includes doping, powdering, pressing and sintering in sequence.

[0022] Preferably, the sintering includes low-temperature sintering and high-temperature sintering; the temperature of the low-temperature sintering is 600-1100℃; and the temperature of the high-temperature sintering is 1200-2800℃.

[0023] Preferably, the low-temperature sintering is carried out in a hydrogen atmosphere, first at 800°C for 1 hour, and then at 1100°C for 1 hour.

[0024] It should be noted that the purpose of low-temperature sintering is to stimulate in-situ chemical reactions and remove gases to achieve interface optimization. On the one hand, it obtains high-strength and tough coherent phase boundaries, and on the other hand, it purifies grain boundaries, reduces the content of harmful oxygen, and improves processability.

[0025] Preferably, the high-temperature sintering is carried out in a hydrogen atmosphere at a temperature of 2000-2800℃ for 2-12 hours.

[0026] Preferably, the doping is achieved by uniformly mixing a tungsten source and a rare earth compound through solid-phase doping or spray drying; the tungsten source includes one or more of tungsten powder, tungsten oxide, and ammonium tungstate.

[0027] Preferably, the present invention also provides the application of the above-mentioned high-strength and high-toughness rare-earth tungsten alloy with a coherent interface or the high-strength and high-toughness rare-earth tungsten alloy with a coherent interface prepared by the above-mentioned preparation method, wherein the tungsten alloy is applied to tungsten alloy wire.

[0028] Preferably, the diameter of the tungsten alloy wire is less than 37 μm; when the diameter of the tungsten alloy wire is 30 μm, the tensile strength of the tungsten alloy wire is 7200 MPa.

[0029] Preferably, the yield of the tungsten alloy wire exceeds 90%.

[0030] The principle of this application is as follows: Utilizing the unique phenomenon of coherent and semi-coherent structures formed during the in-situ reaction of rare earth compounds with a tungsten matrix due to reduced surface activity, the phase boundary bonding strength is improved. Furthermore, highly reactive boron (B) or carbon (C) reacts chemically with adsorbed and dissolved oxygen in the tungsten matrix under relatively low-temperature conditions (600-1100℃) during pre-sintering (low-temperature sintering), generating volatile oxides that escape, preventing closed pores and defects during subsequent high-temperature sintering (1200-2800℃). This further reduces the content of harmful oxygen, purifies grain boundaries, and improves grain boundary bonding strength. Ultimately, based on the dual optimization of phase boundaries and grain boundaries, a high-strength and high-toughness tungsten alloy is obtained.

[0031] (1) The reaction principle of lanthanum boride (a rare earth compound) with adsorbed oxygen and dissolved oxygen during low-temperature sintering is shown in the following reaction formula:

[0032] 4LaB6 + 21O2 = 2La2O3 + 12B2O3

[0033] (2) The reaction principle of carbon-containing rare earth compounds with adsorbed oxygen and dissolved oxygen in low-temperature sintering is as follows: carbon-containing rare earth compounds are directly carbonized in low-temperature pre-sintering to generate La2O3 and carbon residue. The carbon residue reacts with free oxygen and hydrogen to generate carbon dioxide, carbon monoxide or methane.

[0034] Example 1

[0035] A high-strength and high-toughness rare-earth tungsten alloy with a coherent interface has the following material element composition: lanthanum boride 1 wt% and W 99%.

[0036] A method for preparing a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface includes the following steps:

[0037] Step 1, doping and powder preparation: Mix lanthanum boride with tungsten powder using a ball mill or a fly knife + plow knife mixer to reduce particle size and achieve uniform distribution;

[0038] Step 2, Powder pressing: The powder is pressed into compacts weighing 1-5 kg ​​each using isostatic pressing. The compacts are then pre-sintered at low temperature in a hydrogen atmosphere. The compacts are first held at 800℃ for 1 hour and then at 1100℃ for 1 hour to activate the in-situ reaction, form a coherent interface, reduce the content of harmful oxygen, and increase the strength of the compacts.

[0039] Step 3, High-temperature sintering: High-temperature sintering (hydrogen, 2300℃, 4 hours) is carried out to achieve densification and obtain sintered billets.

[0040] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0041] It should be noted that the schematic diagram of the tungsten-lanthanum alloy phase boundary in this embodiment is as follows: Figure 1 As shown, the main method is to obtain a coherent interface between lanthanum oxide and tungsten matrix through in-situ reaction, thereby reducing the interfacial activity energy and improving strength and toughness. The two can deform in coordination, making it less prone to wire breakage during subsequent processing.

[0042] Example 2

[0043] A high-strength and high-toughness rare-earth tungsten alloy with a coherent interface has the following material element composition: 1 wt% lanthanum acetate and 99% W.

[0044] A method for preparing a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface includes the following steps:

[0045] Step 1, doping and powdering: Lanthanum acetate is mixed with tungsten powder by ball milling or by a fly knife + plow mixer to reduce particle size and achieve uniform distribution;

[0046] Step 2, Powder pressing: The powder is pressed into compacts weighing 1-5 kg ​​each using isostatic pressing. The compacts are then pre-sintered at low temperature in a hydrogen atmosphere. The compacts are first held at 800℃ for 1 hour and then at 1100℃ for 1 hour to activate the in-situ reaction, form a coherent interface, reduce the content of harmful oxygen, and increase the strength of the compacts.

[0047] Step 3, High-temperature sintering: High-temperature sintering (hydrogen, 2300℃, 4 hours) is carried out to achieve densification and obtain sintered billets.

[0048] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0049] Example 3

[0050] A high-strength and high-toughness rare-earth tungsten alloy with a coherent interface has the following material element composition: 1 wt% lanthanum acetylacetonate and 99% W.

[0051] A method for preparing a high-strength and high-toughness rare-earth tungsten alloy with a coherent interface includes the following steps:

[0052] Step 1, doping and powdering: Mix lanthanum acetylacetone with tungsten powder using a ball mill or a fly knife + plow mixer to reduce particle size and achieve uniform distribution;

[0053] Step 2, Powder pressing: The powder is pressed into compacts weighing 1-5 kg ​​each using isostatic pressing. The compacts are then pre-sintered at low temperature in a hydrogen atmosphere. The compacts are first held at 800℃ for 1 hour and then at 1100℃ for 1 hour to activate the in-situ reaction, form a coherent interface, reduce the content of harmful oxygen, and increase the strength of the compacts.

[0054] Step 3, High-temperature sintering: High-temperature sintering (hydrogen, 2300℃, 4 hours) is carried out to achieve densification and obtain sintered billets.

[0055] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that the elemental composition of the materials is: 1% La2O3 and 99% W.

[0058] The other steps and parameters are the same as in Example 1.

[0059] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that the elemental composition of the materials is: La(OH)3 is 1% and W is 99%.

[0062] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0063] The other steps and parameters are the same as in Example 1.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is that low-temperature pre-sintering is not performed; the other steps, parameters, and material element composition are the same as in Example 1.

[0066] The above sintered billets were made into 37μm tungsten alloy wires using conventional wire drawing methods. The tensile strength and finished product qualification rate are shown in Table 1.

[0067] Table 1:

[0068]

[0069]

[0070] It should be noted that the doping in the above embodiments is only a simple solid-solid mixing example. Other methods of solid-liquid or liquid-liquid mixing are also within the scope of protection of this application, and will not be listed here.

[0071] The advantages of this application are: the interface control method provided by this invention can effectively improve the tensile strength and machinability of the alloy, which is beneficial to the synergistic improvement of wire strength and yield. Therefore, by using the high-strength and high-toughness rare-earth tungsten alloy provided by this invention, a coherent interface is obtained through in-situ reaction by adding one or more rare-earth compounds, and the content of harmful oxygen is reduced, thereby reducing wire breakage and improving yield. In addition, with further process optimization, including the addition of other solid solution strengthening metal elements, it is possible to achieve mass production of alloy wires with finer specifications, higher strength, and better toughness.

[0072] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-strength, high-toughness rare-earth tungsten alloy with a coherent interface, characterized in that, The tungsten alloy comprises tungsten and rare earth compounds; the rare earth elements in the rare earth element compounds are any one or more of neodymium, yttrium, europium, lanthanum, cerium, and scandium; the rare earth compounds are borides, carbonyl compounds, acetates, or acetone salts of rare earth elements; wherein, the coherent interface is obtained by sintering tungsten and rare earth compounds at a low temperature of 600-1100℃; the amount of rare earth compounds added is 0.01wt%~5wt%; the tungsten alloy is used in tungsten alloy wire, which is used in material cutting, cable, rope, or textile applications.

2. The method for preparing a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface according to claim 1, characterized in that, The process includes, in sequence, doping, powdering, pressing, and sintering.

3. The method for preparing a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface according to claim 2, characterized in that, The sintering includes low-temperature sintering and high-temperature sintering; the temperature of the low-temperature sintering is 600-1100℃; and the temperature of the high-temperature sintering is 1200-2800℃.

4. The method for preparing a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface according to claim 3, characterized in that, The low-temperature sintering is carried out in a hydrogen atmosphere, first at 800°C for 1 hour, and then at 1100°C for 1 hour.

5. The method for preparing a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface according to claim 3, characterized in that, The high-temperature sintering is carried out in a hydrogen atmosphere at 2000-2800℃ for 2-12 hours.

6. The method for preparing a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface according to claim 3, characterized in that, The doping is achieved by uniformly mixing a tungsten source and a rare earth compound through solid-phase doping or spray drying; the tungsten source includes one or more of tungsten powder, tungsten oxide, and ammonium tungstate.

7. The application of a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface as described in claim 1, or a high-strength, high-toughness rare-earth tungsten alloy with a coherent interface prepared by the preparation method according to any one of claims 2-6, characterized in that, The tungsten alloy is used in tungsten alloy wire, which is used in material cutting, cable, rope or textile fields.

8. The application according to claim 7, characterized in that, The diameter of the tungsten alloy wire is less than 37µm; when the diameter of the tungsten alloy wire is 30µm, the tensile strength of the tungsten alloy wire is 7200MPa.

9. In the application according to claim 8, the yield of the tungsten alloy wire exceeds 90%.

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