Tantalum-tungsten-based nano composite target material and preparation method thereof

Abstract

The invention relates to the technical field of metal material preparation, in particular to a tantalum-tungsten-based nano composite target material and a preparation method thereof. The method comprises the following steps: smelting a high-purity tantalum block and a high-purity tungsten block, and casting to obtain a tantalum-tungsten prealloy cast ingot; the tantalum-tungsten pre-alloy cast ingot is subjected to atomization powder making, and Ta-W alloy powder is obtained; the Ta-W alloy powder is mixed with a nano carbon material, and TaW-C mixed powder is obtained; and the TaW-C mixed powder is subjected to magnetic field assisted sintering, grain oriented growth is induced, aftertreatment is conducted, and the tantalum-tungsten-based nano composite target material is obtained. The magnetic field assisted sintering adopts a one-way static magnetic field along the direction vertical to the target surface, and the magnetic field intensity is 2-10T. According to the preparation method, the Ta-W-based nano composite target material with high density, uniform tissue and texture orientation can be prepared, and the deposited film has the characteristics of low stress, high flexibility and the like, and meets the use requirements of a flexible implanted electrode.

Description

Technical Field

[0001] This invention relates to the field of metal material preparation technology, and in particular to a tantalum-tungsten based nanocomposite target and its preparation method. Background Technology

[0002] Tantalum-tungsten alloys, as a class of metallic materials that combine high strength, corrosion resistance, and good biocompatibility, have been applied in medical implantable devices such as cardiovascular stents. In recent years, new application requirements for tungsten materials have emerged in fields such as flexible electronics and biosensing. In particular, in flexible electrodes for brain-computer interfaces, tungsten materials used as conductive thin film layers need to simultaneously meet stringent requirements such as flexibility, low internal stress, and stable conductivity.

[0003] However, traditionally prepared Ta-W sputtering targets primarily serve hard electronic devices, such as interconnect layers and diffusion barrier layers in integrated circuits. These typically focus on high material purity, grain refinement, compositional and microstructure uniformity, and improving sputtering rate and film thickness uniformity. For example, patent application CN119489150A utilizes different processes such as forging, rolling, and additive manufacturing to improve the performance of Ta-W alloys. Patent application CN119328162A constructs a short-process preparation method that mixes Ta-10W pre-alloyed powder and high-purity Ta powder in a specific ratio, then forms the alloy through selective laser melting, followed by high-vacuum stress-relief heat treatment. This method achieves Ta-W alloys with precisely controllable W composition within the range of 0–10 wt.%, dense microstructure, and minimal defects. The resulting materials exhibit tensile strengths of 550–726 MPa and elongation of 29–40%, significantly shortening the traditional ingot forging process. However, most of these methods are designed for Ta-W films on rigid substrates. When used on flexible polymer substrates, new problems may arise: Ta-W films, due to their high hardness and stress, are prone to cracking and delamination under repeated bending at small curvatures, leading to device failure. Furthermore, adding carbon nanomaterials to metal matrix composites presents challenges. Introducing carbon nanotubes (CNTs) and other nano-carbon materials into the metal matrix can improve strength and new properties, but it also presents problems such as uneven dispersion and interfacial reactions. In particular, carbon nanotubes are prone to chemical reactions with certain reactive metals during high-energy ball milling or sintering, forming metal carbides. Tantalum, as a strong carbide-forming element, readily reacts with carbon at high temperatures to form TaC. If not controlled, the nano-carbon reinforcing phase may be completely carbonized during target sintering, losing its original morphology and function. Therefore, current technologies lack effective methods in this regard, and there are no reports of successfully introducing nano-carbon materials into Ta-W targets while ensuring they are not completely carbonized.

[0004] Currently, there is no known Ta-W target fabrication process specifically designed for flexible brain-computer interface (BCI) electrodes. For example, BCI applications require films with internal stress below 100 MPa and the ability to withstand tens of thousands of bends without fracture, but existing Ta-W films struggle to meet this stringent standard. Furthermore, publicly reported Ta-W fabrication methods lack the application of second-phase toughening and magnetic field-induced texturing processes, and do not include the introduction of conductive phases such as nano-carbon into the Ta-W target fabrication process, nor do they address the stress and reliability issues in flexible electronics by controlling crystal orientation with a magnetic field. Based on these technological gaps, there is an urgent need to propose an innovative Ta-W-based nanocomposite target fabrication method to solve the problems of high internal stress in sputtered films and insufficient bending reliability encountered when using existing Ta-W targets in flexible BCI electrodes. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a tantalum-tungsten-based nanocomposite target and its preparation method. This invention enables the preparation of Ta-W-based nanocomposite targets with high density, uniform structure, and texture orientation. The deposited thin films exhibit low stress and high flexibility, meeting the requirements for flexible implantable electrodes.

[0006] In a first aspect, the present invention provides a method for preparing a tantalum-tungsten-based nanocomposite target, comprising: 1) High-purity tantalum blocks and high-purity tungsten blocks are smelted and cast to obtain tantalum-tungsten pre-alloy ingots.

[0007] 2) The tantalum-tungsten pre-alloyed ingot is atomized to obtain Ta-W alloy powder.

[0008] 3) The Ta-W alloy powder is mixed with nano-carbon material to obtain TaW-C mixed powder.

[0009] 4) The TaW-C mixed powder is subjected to magnetic field-assisted sintering to induce directional grain growth, followed by post-processing to obtain a tantalum-tungsten-based nanocomposite target. The magnetic field-assisted sintering employs a unidirectional static magnetic field perpendicular to the target surface, with a magnetic field strength of 2~10T. In this invention, by introducing a nano-carbon reinforcing phase into the Ta-W alloy powder and employing strong magnetic field-assisted sintering, a Ta-W-based nanocomposite target with high density, uniform structure, and texture orientation can be prepared. The deposited film thus exhibits low stress and high flexibility, meeting the requirements for flexible implantable electrodes. Specifically, this invention, through a special process combination, enables the prepared target to possess the following excellent characteristics: a relative density close to 100%, and grain orientation... <001> It exhibits preferential orientation and highly uniform composition distribution, and demonstrates significantly reduced residual stress and significantly improved bending durability in thin film deposition applications.

[0010] Preferably, in step 1), the tantalum-tungsten pre-alloy ingot has a tungsten content of ≤12%, preferably 2%~10%. For example, 3%, 5%, 7%, 8%, 9%, 10%, etc. In this invention, the tungsten content in the pre-alloy is controlled to balance the resistivity and stress properties of the alloy film.

[0011] Further preferably, in step 1), the melting temperature is 2000~2500℃, the time is 10~100min, and the vacuum degree is ≤10. -3 Pa.

[0012] Preferably, the melting is vacuum induction melting, vacuum consumable arc melting, or electron beam melting; in this invention, the tantalum-tungsten pre-alloy melting is carried out in a vacuum induction melting furnace, or in a vacuum consumable arc furnace / electron beam furnace for melting and refining, to ensure the high purity and uniformity of the tantalum-tungsten pre-alloy.

[0013] Preferably, the tantalum-tungsten pre-alloy ingot is cylindrical with a diameter of 20-80 mm.

[0014] Preferably, in step 2), the atomization powdering is plasma rotating electrode atomization (PREP) or high-pressure gas atomization; the particle size D50 of the Ta-W alloy powder is 50~150μm.

[0015] Preferably, in the Ta-W alloy powder, the mass fraction of powder with a particle size of 50~150μm is not less than 90%, and the oxygen content of the powder is ≤1000ppm, so as to ensure the uniformity of the composition and structure of the target material.

[0016] Preferably, the tantalum-tungsten alloy powder contains 2% to 12% by mass, for example, 2%, 4%, 6%, 8%, 8%, 10%, 12%, and more preferably 8% to 10%.

[0017] Preferably, in step 3), the nano-carbon material includes one or more of amorphous carbon powder, multi-walled carbon nanotubes, and graphene; preferably, the particle size of the amorphous carbon powder is 0~200nm; the outer diameter of the multi-walled carbon nanotubes is 5~50nm and the length is 0.5~5μm; the thickness of the graphene is 1~20nm and the sheet diameter is 0.5~5μm.

[0018] Preferably, the nano-carbon material is mixed with Ta-W alloy powder and ball-milled. The mass of the nano-carbon material accounts for 0.01% to 1.0% of the mass of the Ta-W alloy powder, for example, 0.01%, 0.05%, 0.2%, 0.5%, 0.8%, 0.9%, 1.0%, etc. Anhydrous ethanol is used as the dispersion medium, the ball-to-powder ratio is 5 to 15:1, the ball milling time is 1 to 6 hours, and a planetary ball mill is preferably used for ball milling at a speed of 200 to 300 rpm.

[0019] Further preferably, step 3) also includes a step of surface modification or coating treatment of the nano-carbon material to block the direct reaction between carbon and the tantalum-tungsten matrix; preferably, a ceramic material layer is coated on the surface of the nano-carbon material using chemical vapor deposition or atomic layer deposition, wherein the ceramic material layer is preferably boron nitride.

[0020] Preferably, in steps 2) and 3), the inert atmosphere is high-purity argon gas with a purity of ≥99.999% to control the oxygen impurity content within the stated range.

[0021] Preferably, in step 4), the sintering temperature is 1000~1500℃ and the pressure is 25~35MPa; preferably, the sintering holding time is 1~6h, the heating rate is 10~100℃ / min, and the sintering is carried out in a vacuum environment ≤10 -2 The process is carried out under a Pa or protective atmosphere. Preferably, the induced grains grow preferentially along the (001) orientation; the magnetic field strength is preferably 4~8T, for example 4T, 5T, 6T, 7T, 8T, etc.

[0022] Further preferred, in step 4), after sintering, the obtained target blank is subjected to medium-temperature vacuum annealing to release residual stress and stabilize the (001) texture; the annealing temperature is 800~1000℃ and the annealing time is 1~4h.

[0023] Further preferred, in step 4), the post-processing also includes cooling and machining.

[0024] According to the present invention, by optimizing the powder metallurgy process, a pre-alloy ingot with uniform composition is first obtained by vacuum melting of Ta-W pre-alloys. Then, a high-purity spherical alloy powder is obtained by powder preparation. Next, nano-carbon materials are introduced and mixed with the alloy powder and ball-milled for uniform dispersion. Subsequently, the powder is sintered under the assistance of a strong magnetic field and finally machined to obtain a high-density tantalum-tungsten-based nanocomposite target with (001) texture orientation. This effectively solves the problems of high internal stress and poor bending life of traditional tantalum-tungsten targets in flexible electronics applications. The target prepared by this method has the characteristics of highly uniform composition and structure, low internal stress, and good toughness. When used for thin film deposition of flexible electrodes such as brain-computer interfaces, it can significantly improve the stability and service life of the film.

[0025] Secondly, the present invention provides a tantalum-tungsten based nanocomposite target obtained by the preparation method described above.

[0026] Preferably, the tantalum-tungsten based nanocomposite target comprises a tantalum-tungsten alloy matrix and a nano-carbon reinforcing phase dispersed in the matrix, the tantalum-tungsten based nanocomposite target has a preferred orientation of (001) crystal plane; the relative density of the tantalum-tungsten based nanocomposite target is ≥99%.

[0027] Further preferably, the relative density of the tantalum-tungsten based nanocomposite target is 99%~100%, for example, 99%, 99.2%, 99.5%, 99.8%, 99.9%, etc.; the enhancement coefficient of the (001) crystal plane texture intensity perpendicular to the target surface direction relative to random polycrystalline is ≥2; and the tungsten content deviation in the tantalum-tungsten based nanocomposite target is ≤3%.

[0028] According to some embodiments of the present invention, the method for preparing the tantalum-tungsten-based nanocomposite target, which is prepared by powder metallurgy combined with nanocomposite and magnetic field-induced texturing processes, includes the following steps: 1) Pre-alloying melting: High-purity tantalum and tungsten blocks are loaded into a vacuum induction melting furnace or electron beam melting device at a set mass ratio and cast into cylindrical tantalum-tungsten pre-alloy ingots with a diameter of 20-80 mm; preferably, high-purity tantalum and tungsten blocks are weighed according to a predetermined mass ratio (e.g., Ta:W=92:8~90:10) and placed into a vacuum melting furnace, and the vacuum is evacuated to ≤10. -3 Pa is heated and melted in the range of 2000~2500℃ and kept refined for 10~100min, and then cast to obtain a tantalum-tungsten pre-alloyed cylindrical ingot with a diameter of about 20~80mm.

[0029] 2) Powder preparation: The pre-alloyed ingot is machined into powder-making raw material, and a corresponding powder-making process is used in an inert atmosphere to obtain spherical Ta-W alloy powder; preferably, the pre-alloyed ingot is machined into powder-making raw material, and a corresponding powder-making process is used in an inert atmosphere; the powder obtained is spherical Ta-W alloy powder with a particle size D50 of 50~150μm and an oxygen content of ≤1000ppm; preferably, the yield of powder in the 50~150μm particle size range is controlled to be not less than 90% to ensure the compositional uniformity of the final target material.

[0030] 3) Nano-carbon mixed powder: Select nano-carbon particles and / or multi-walled carbon nanotubes and / or graphene, and add them to the Ta-W alloy powder for mixing; place the mixture in an inert atmosphere ball mill jar for ball milling, and then dry it at low temperature to obtain a uniformly dispersed TaW-C mixed powder; before mixing the powder, the nano-carbon material is coated to enhance stability; preferably, nano-carbon powder with a particle size of 0~200nm and / or multi-walled carbon nanotubes (outer diameter 10~50nm, length 0.5~5μm) and / or graphene (sheet diameter 0.5~100μm) are selected as carbon nano-reinforcing phases and added to the alloy powder at a ratio of 0.01~1.0wt.% of the mass of Ta-W alloy powder. Before mixing the powders, the nano-carbon materials are coated, such as by chemical vapor deposition (CVD) or atomic layer deposition (ALD) to coat two-dimensional boron nitride (h-BN) to enhance stability. Under an inert atmosphere, the powder mixture is placed in a ball mill jar, anhydrous ethanol is added as a dispersion medium, the ball-to-powder mass ratio is controlled at 5~15:1, and the mixture is ball-milled for 1~6 hours to ensure that the nano-carbon is uniformly dispersed between the Ta-W powders. After ball milling, the solvent is removed by low-temperature drying to obtain a uniformly distributed Ta-W / nano-carbon mixed powder. To enhance the interfacial bonding between the carbon nanophase and the alloy matrix, the carbon nanomaterials can be pre-treated with surface functionalization treatments such as acidification or metal coating.

[0031] 4) Sintering: The TaW-C mixed powder is loaded into a preheated graphite mold, the mold size of which is designed according to the target diameter. Sintering is carried out in a vacuum environment or protective atmosphere, and the unidirectional static magnetic field is applied during the sintering process. Then, the powder is cooled to room temperature in the furnace to obtain a target blank, which is then machined to obtain a tantalum-tungsten based nanocomposite target. Preferably, the mixed powder is loaded into a graphite mold that matches the size of the target, and sintered in a vacuum (preferably ≤10). -2 Sintering is carried out under a protective atmosphere or at a pressure of 25-35 MPa. The sintering temperature is set at 1000-1500℃. During the heating to the sintering temperature and the holding stage, a uniaxial pressure of 25-35 MPa is applied. The holding time is 1-6 h, and the heating rate is controlled at 10-100℃ / min. At the same time, a constant magnetic field of 2-10 T is applied along the direction perpendicular to the target surface throughout the sintering process to induce the alloy grains to preferentially grow along the (001) orientation. After sintering, the furnace is cooled to room temperature, the pressure is released, and the sintered tantalum-tungsten based nanocomposite target blank is taken out. The blank is then machined (turning, grinding, etc.) to obtain a target material with the required dimensions. If necessary, the target blank is further vacuum annealed at 800-1000℃ for 1-4 h to release the residual stress of sintering and stabilize the (001) texture.

[0032] The beneficial effects of this invention are at least as follows: 1) Achieving high-density and texture-controllable Ta-W targets: By combining powder preparation and sintering, Ta-W targets with near-theoretical density (above 99%) can be obtained. Simultaneously, applying a high-intensity magnetic field during sintering induces (001) texture, resulting in highly uniform grain orientation in the prepared target material, overcoming the problem of large anisotropy in conventional sintered materials. This textured target material provides a more uniform and stable deposition rate during sputtering and effectively reduces residual stress within the target material and the film.

[0033] 2) Nanoscale carbon reinforcement significantly reduces film stress: This invention introduces a small amount of uniformly dispersed nanoscale carbon phase into the Ta-W alloy, forming a metal-carbon nanocomposite material. On the one hand, nanoscale carbon, as a second phase, can hinder grain growth, refine the microstructure, and reduce thermal stress concentration; on the other hand, carbonaceous materials have low Young's modulus and high surface energy, and when dispersed at the grain boundaries of the target material, they can absorb particle impact energy during sputtering, playing a role in stress buffering and preventing crack propagation. Therefore, the internal stress of the film deposited using this composite target is significantly lower than that of the Ta-W film without added carbon, which helps to improve the stability of the film under repeated mechanical bending.

[0034] 3) Process Innovation Enhances Overall Target Performance: This invention integrates innovative techniques such as powder metallurgy, nanomaterial composites, and magnetic field-induced texturing, representing a novel process route developed to address the new demands of flexible electronics applications on Ta-W materials. The tantalum-tungsten based nanocomposite targets prepared using this method maintain high conductivity and corrosion resistance while significantly improving the material's resistance to mechanical fatigue and the quality of thin film deposition. Compared to the traditional casting-forging-rolling process, this method offers a relatively shorter and more controllable process, enabling the preparation of large-size, highly uniform target products to meet the needs of industrial applications. When this target is used for thin film deposition in flexible brain-computer interface electrodes, it effectively prevents film cracking and peeling, significantly extending the electrode's service life and improving signal reliability. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a process flow diagram for preparing tantalum-tungsten-based nanocomposite targets provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0039] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0040] Example 1 This embodiment provides a Ta-8W-based nanocomposite target, the preparation method of which is as follows: Figure 1 As shown, the details are as follows: a) Pre-alloy smelting: High-purity Ta and W raw materials are mixed in a ratio of Ta:W=92:8 (tungsten content 8wt.%), and smelted under a vacuum of approximately 5×10⁻⁶. -3 The alloy was melted at approximately 2350°C for 40 minutes under Pa conditions and then cast into Ta-8W pre-alloyed ingots with a diameter of approximately 60 mm. The resulting alloy ingots had a uniform composition and no obvious macroscopic segregation.

[0041] b) Powder preparation: The pre-alloyed ingot was processed into slender rods with a diameter of 20 mm. Spherical Ta-8W alloy powder was prepared by plasma rotating electrode atomization (PREP) under a high-purity Ar atmosphere. The atomization parameters were set as follows: plasma current 600 A and rotation speed 40,000 rpm. The powder obtained after atomization was collected, and the fraction with a particle size of 10-45 μm was screened for subsequent preparation. The oxygen content of the powder was measured to be approximately 200 ppm.

[0042] c) Nanocarbon mixing: Amorphous carbon powder with an average particle size of approximately 100 nm and multi-walled carbon nanotubes (MWCNTs) with an average outer diameter of approximately 30 nm were mixed at a 1:1 ratio as the carbon source. Before mixing, the nanocarbon material was coated with two-dimensional boron nitride (h-BN) using chemical vapor deposition (CVD) to enhance stability. This coated material was then added to the Ta-8W powder at a mass fraction of approximately 1.0 wt.%. The mixed powder was placed in a ball mill jar filled with Ar gas, and an appropriate amount of anhydrous ethanol was added. The ball-to-material mass ratio was controlled at approximately 10:1, and the mixture was ball-milled at 250 rpm for 4 hours. After ball milling, the slurry was removed and vacuum-dried at 60°C for 12 hours to obtain a uniform Ta-8W-1C composite powder.

[0043] d) Hot pressing sintering: The above composite powder is loaded into a circular graphite mold with a diameter of 210 mm and compacted, with a pressure of ≤5×10⁻⁶ mm. - 2 Heating under vacuum with an axial pressure of 32 MPa, the temperature was increased to 1250 °C at a rate of 50 °C / min and held for 2 hours. Simultaneously, a constant magnetic field of 5 T was applied perpendicular to the pressing surface. After sintering, the target blank was cooled to room temperature in the furnace and removed; its relative density was 99.5%.

[0044] e) Machining and Annealing: The sintered target blank is machined to its final dimensions (φ200mm × 8mm thickness), and the target surface roughness Ra is polished to <0.2μm. The resulting target material is then subjected to annealing at 900℃ under vacuum ≤1×10⁻⁶. -3 Annealing at Pa for 2 hours further reduces internal stress and stabilizes the texture.

[0045] Performance Testing: EBSD pole figure analysis of the target cross-section texture showed that the (001) texture intensity in the normal direction of the target was approximately 2.5 times that of random orientation, indicating that magnetic field-assisted sintering successfully induced a significant (001) preferred orientation. EDS composition analysis showed that the W content at different locations of the target was uniformly distributed with a deviation of less than 3%. TEM observation revealed that the nano-carbon phase was mainly located at the Ta-W grain boundaries, exhibiting a network-like distribution. The relative density of the target was measured to be approximately 99.5%, and the Vickers hardness was uniformly distributed within the range of 230–260 hV. This target was used to prepare films on flexible polyimide substrates. The results showed that the obtained Ta-WC film had lower residual internal stress and higher bending stability compared to traditional Ta-W films: after repeated bending at a bending radius of 1 mm for 1 × 10⁻⁶ mm, the film exhibited better bending performance. 4 Subsequently, the change rate of film resistance remained within 5%, while the Ta-W film without added carbon cracked under the same test conditions, resulting in a resistance drift exceeding 15%. This result demonstrates that the target material prepared by the method of this invention can significantly improve the reliability and durability of flexible electrode films.

[0046] Example 2 This embodiment provides a Ta-10W-based nanocomposite target, the preparation method of which is as follows: a) First, select high-purity Ta and W raw materials according to the Ta:W ratio of 90:10 (tungsten content 10wt.%), and smelt them in a vacuum consumable arc furnace (vacuum degree approximately 8×10). -4 The mixture was heated to approximately 2300°C and refined for approximately 20 minutes to obtain a Ta-10W pre-alloyed ingot (approximately 30 mm in diameter).

[0047] b) The pre-alloyed ingot is pulverized using a high-pressure gas atomization method under high-purity Ar protection. The atomization system is first evacuated to a vacuum level of ≤5×10⁻⁶. -3 The gas is charged with Ar (≥99.999% purity) as a protective and atomizing gas at a back-charging pressure of approximately 0.04 MPa. The Ta-10W pre-alloyed melt is heated to approximately 100°C above the liquidus and then atomized at an atomizing gas pressure of approximately 3.5 MPa to obtain spherical Ta-10W powder (D50 approximately 100 μm). Powder with a particle size of 20–100 μm is screened for subsequent processes (oxygen content approximately 400 ppm).

[0048] c) Graphene nanosheets with an average thickness of approximately 5 nm and a sheet diameter of 2.5 μm were used as the carbon reinforcing phase (high specific surface area, easy to form a conductive network). This carbon nanomaterial was coated with two-dimensional boron nitride (h-BN) via CVD to enhance stability. Subsequently, approximately 0.8 wt.% Ta-10W powder was added, and the mixture was ball-milled for 2 hours in an Ar atmosphere at a ball-to-powder ratio of approximately 8:1. The resulting powder was dried to obtain Ta-10W-0.8C composite powder.

[0049] d) The composite powder is loaded into a graphite mold and subjected to vacuum (≤1×10⁻⁶). -2 The target blank was sintered at 1300℃ with a heating rate of 40℃ / min and held at 30MPa for 3 hours. An 8T magnetic field was applied vertically throughout the sintering process to induce texture. After sintering, the blank was cooled in the furnace and removed. Density measurements showed a relative density of approximately 99%.

[0050] e) The target blank is processed into a target material with a diameter of φ150mm and a thickness of 5mm and then vacuum annealed (850℃, 2h).

[0051] Performance Testing: EBSD pole figure analysis showed a distinct (001) preferred orientation along the normal direction of the target material, with a (001) texture enhancement coefficient of approximately 2.4. EDS surface scanning results indicated that W was uniformly distributed across the cross-section and in-plane of the target material, with W content deviations in different test areas below 3%. The relative density of the target material, measured by the Archimedes method, was approximately 99.0%. The graphene-reinforcing phase was mainly distributed at grain boundaries and intergranular regions, exhibiting relatively uniform dispersion without significant large-size agglomerations. Compared to Comparative Example 1, this embodiment, due to the introduction of a surface-coated nano-carbon reinforcing phase, further improved the uniformity of the target material's structure and stress buffering effect while maintaining high density and a distinct texture orientation. This demonstrates that even when the tungsten content is increased to 10 wt.%, the method of this invention can still yield a tantalum-tungsten-based nanocomposite target with excellent comprehensive performance.

[0052] Comparative Example 1 The same method as in Example 2 was used, except that no nano-carbon material was added.

[0053] The test results of Example 2 and Comparative Example 1 show that the Ta-10W-1.0C target material of Example 2 has similar microstructure characteristics to that of Example 1: (001) significant texture and highly uniform composition. The deposited film has a bending radius of 1 mm and a microstructure of 1 × 10⁻⁶ mm. 4 The resistivity change rate after 5000 bending cycles was approximately 4%, and no cracks appeared on the film surface. In contrast, the Ta-10W sputtered film prepared by the same process but without added carbon in Comparative Example 1 cracked and failed after 5000 bending cycles. This demonstrates that even with a tungsten content increased to 10 wt.%, the nanocomposite target prepared by the method of this invention can still effectively reduce film stress and improve its mechanical stability.

[0054] Example 3 This embodiment provides a Ta-14W-based nanocomposite target, the preparation method of which is as follows: a) Pre-alloying melting: High-purity Ta and W raw materials are mixed in a ratio of Ta:W = 86:14 (tungsten content 14 wt.%), and melted in a vacuum induction furnace at a vacuum degree of approximately 6 × 10⁻⁶. -4 The material was melted and refined at approximately 2280°C for about 30 minutes and then cast into a Ta-14W pre-alloyed ingot with a diameter of approximately 50 mm.

[0055] b) Powder preparation: The pre-alloyed ingot is mechanically processed into powder-making raw material, and powder is prepared by high-pressure gas atomization under high-purity Ar protection; the atomization system is first evacuated to ≤5×10 -3The solution is then charged with Ar gas of ≥99.999% purity as a protective and atomizing gas at a back-charging pressure of approximately 0.04 MPa. The melt is heated to approximately 100°C above the liquidus line and then atomized at an atomizing gas pressure of approximately 3.2 MPa to obtain spherical Ta-14W alloy powder with a powder D50 of approximately 90 μm. Powder with a particle size of 50–120 μm is screened for subsequent processes, and the powder oxygen content is approximately 350 ppm.

[0056] c) Nanocarbon mixing: Graphene nanosheets and multi-walled carbon nanotubes were mixed at a mass ratio of 1:1 as the carbon reinforcing phase; before mixing, an ultrathin h-BN layer was coated on the surface of the nanocarbon material by CVD and added to Ta-14W powder with a mass fraction of about 0.3 wt.%; then, an appropriate amount of anhydrous ethanol was added as a dispersion medium under Ar atmosphere, the ball-to-powder ratio was controlled at about 8:1, and the mixture was ball-milled at 220 rpm for 3 h. After ball milling, it was vacuum dried at 60 °C for 10 h to obtain uniformly dispersed Ta-14W-0.3C composite powder.

[0057] d) Sintering: The above composite powder is loaded into a graphite mold and sintered under a vacuum degree ≤8×10 -3 Hot pressing sintering was performed under Pa conditions; the temperature was increased to 1240℃ at 40℃ / min, a uniaxial pressure of 30MPa was applied and held for 2 hours; at the same time, a constant magnetic field of 5T was applied in the direction perpendicular to the target surface. After sintering, the target blank was cooled to room temperature in the furnace to obtain a sintered target blank with a relative density of about 99.3%.

[0058] e) Machining and Annealing: The obtained target blank is machined into a target material with a diameter of φ150mm and a thickness of 6mm, and then subjected to annealing at 880℃ and a vacuum of ≤1×10⁻⁶. -3 Annealing at Pa for 2 hours.

[0059] Performance Testing: EBSD pole figure analysis showed that the (001) texture enhancement coefficient in the normal direction of the target material was approximately 2.2. EDS surface scanning results indicated that W was uniformly distributed in the cross-section and in-plane of the target material, with W content deviations in different test areas less than 3%. The relative density of the target material, measured by the Archimedes method, was approximately 99.3%. The nano-carbon reinforcing phase was mainly distributed near the grain boundaries, with no obvious large-size agglomerates observed. Compared to Examples 1 and 2, this example, due to the excessively high tungsten content and relatively low nano-carbon content, exhibited slightly weaker texture orientation, microstructure density, and stress buffering effect. However, its overall performance was still significantly better than that of Comparative Example 1, which did not contain nano-carbon or had no magnetic field applied.

[0060] Example 4 This embodiment provides a Ta-8W-based nanocomposite target, the preparation method of which is as follows: a) Pre-alloying smelting: High-purity Ta and W raw materials are mixed in a ratio of Ta:W = 92:8 (tungsten content 8 wt.%) and smelted in a vacuum arc furnace at a vacuum degree of approximately 7 × 10⁻⁶.-4 The Ta-8W pre-alloyed ingot with a diameter of about 40 mm was obtained by melting and refining at about 2320°C for about 25 minutes.

[0061] b) Powder preparation: The pre-alloyed ingot is powdered by high-pressure gas atomization under high-purity Ar protection; the atomization system is evacuated to ≤5×10⁻⁶. -3 After Pa, Ar gas with a purity ≥99.999% is introduced at a back-charging pressure of approximately 0.04 MPa. The pre-alloyed melt is then superheated to approximately 120°C and atomized at an atomizing gas pressure of approximately 3.5 MPa to obtain spherical Ta-8W alloy powder with a D50 of approximately 95 μm. Powder with a particle size of 50~120 μm is screened for subsequent processes, and the powder oxygen content is approximately 450 ppm.

[0062] c) Nano-carbon mixing: Amorphous carbon powder with an average particle size of about 100 nm and multi-walled carbon nanotubes with an average outer diameter of about 20-30 nm were mixed at a mass ratio of 1:1 as the carbon reinforcing phase, with a total addition amount of 0.80 wt.% of the Ta-8W powder mass. In this embodiment, the nano-carbon material was not coated with boron nitride, but only subjected to mixed acid oxidation treatment to introduce carboxyl and hydroxyl functional groups on the surface; then anhydrous ethanol was added as a dispersion medium under Ar atmosphere, the ball-to-powder ratio was controlled at about 10:1, and the mixture was ball-milled at 250 rpm for 3 h, and dried to obtain Ta-8W-0.8C composite powder.

[0063] d) Sintering: The above composite powder is loaded into a graphite mold and sintered under a vacuum degree ≤10. -2 The target blank was heated to 1250℃ at a rate of 50℃ / min under Pa conditions, and then subjected to a pressure of 32MPa and held for 2 hours. Simultaneously, a constant magnetic field of 5T was applied in a direction perpendicular to the target surface. After sintering, the blank was cooled to room temperature in the furnace and removed. The relative density was approximately 99.1%.

[0064] e) Machining and annealing: The target blank is machined into a target material with a diameter of φ200mm and a thickness of 8mm, and then annealed at 900℃ under vacuum for 2 hours.

[0065] Performance Testing: EBSD pole figure analysis showed that the (001) texture enhancement coefficient in the normal direction of the target material was approximately 2.1. EDS surface scanning results indicated that W was uniformly distributed in the cross-section and in-plane of the target material, with W content deviations in different test areas less than 3%. The relative density of the target material, measured by the Archimedes method, was approximately 99.1%. The nano-carbon reinforcing phase was mainly distributed near the grain boundaries, with a small amount of interfacial reaction phase present locally. Compared to Examples 1 and 2, this example, due to the absence of h-BN coating, showed decreased interfacial stability and stress buffering effect, but the overall performance was still better than Comparative Example 1 without nano-carbon addition.

[0066] Example 5 This embodiment provides a Ta-8W-based nanocomposite target, the preparation method of which is as follows: a) Pre-alloying smelting: High-purity Ta and W raw materials are mixed in a ratio of Ta:W = 92:8 (tungsten content 8 wt.%) and smelted in a vacuum induction furnace at a vacuum degree of approximately 5 × 10⁻⁶. -4 The mixture was smelted at approximately 2350°C for 40 minutes and then cast into a Ta-8W pre-alloyed ingot with a diameter of approximately 60 mm.

[0067] b) Powder preparation: The pre-alloyed ingots were powdered using a high-pressure gas atomization method under high-purity Ar protection. The atomization system was first evacuated to a vacuum level ≤5×10⁻⁶. -3 The gas is charged with Ar (≥99.999% purity) as a protective and atomizing gas at a back-charging pressure of approximately 0.04 MPa. The Ta-8W pre-alloyed melt is heated to approximately 100°C above the liquidus and then atomized at an atomizing gas pressure of approximately 3.5 MPa to obtain spherical Ta-8W powder (D50 approximately 100 μm). Powder with a particle size of 20–100 μm is screened for subsequent processes (oxygen content approximately 400 ppm).

[0068] c) Nanocarbon mixing: Amorphous carbon powder with an average particle size of about 100 nm and multi-walled carbon nanotubes with an average outer diameter of about 30 nm were mixed at a mass ratio of 1:1 as carbon source; before mixing, a two-dimensional h-BN layer was coated on the surface of the nanocarbon material by chemical vapor deposition and added to Ta-8W powder at a mass fraction of about 1.0 wt.%; then anhydrous ethanol was added under Ar atmosphere protection, the ball-to-powder ratio was controlled at about 10:1, and the mixture was ball-milled at 250 rpm for 4 h. After drying, Ta-8W-1.0C composite powder was obtained.

[0069] d) Sintering: The above composite powder is loaded into a graphite mold and sintered at a temperature of ≤5×10⁻⁶. -2 Heating was performed under vacuum with an axial pressure of 32 MPa, and the temperature was increased to 1230°C at a rate of 50°C / min, followed by holding at that temperature for 2 hours. In this embodiment, a constant magnetic field of 3T was applied only along the direction perpendicular to the pressing surface. After sintering, the blank was cooled to room temperature in the furnace and removed, with a relative density of approximately 99.0%.

[0070] e) Machining and Annealing: Machining the sintered target blank to φ200mm × 8mm thickness, and annealing it at 900℃ under vacuum ≤1×10 -3 Annealing at Pa for 2 hours.

[0071] Performance Testing: EBSD pole figure analysis showed that the (001) texture enhancement coefficient in the normal direction of the target material was approximately 2.0. EDS surface scanning results indicated that W was uniformly distributed in the cross-section and in-plane of the target material, with W content deviations in different test areas less than 3%. The relative density of the target material, measured by the Archimedes method, was approximately 99.0%. Microstructural observation showed that the nano-carbon reinforcing phase was mainly distributed near the grain boundaries, with relatively uniform overall dispersion and no obvious large-size agglomerations. Compared to Examples 1 and 2, in this example, the magnetic field strength applied during sintering was reduced to below 5T, weakening the magnetic field-induced preferred grain orientation effect. This resulted in a decrease in the target material's texture control ability, microstructure density, and stress buffering effect, but the overall performance was still better than that of Comparative Example 2 without an applied magnetic field.

[0072] Comparative Example 2 This comparative example provides a Ta-8W-based nanocomposite target, the preparation method of which is basically the same as in Example 1, the main difference being that no external static magnetic field is applied during the sintering process. Specifically: a) Pre-alloy smelting: High-purity Ta and W raw materials are mixed in a ratio of Ta:W = 92:8 (tungsten content 8 wt.%), and smelted under a vacuum of approximately 5 × 10⁻⁶. -4 The material was melted at approximately 2350°C for 40 minutes under Pa conditions and then cast into a Ta-8W pre-alloyed ingot with a diameter of approximately 60 mm.

[0073] b) Powder preparation: The pre-alloyed ingots were powdered using a high-pressure gas atomization method under high-purity Ar protection. The atomization system was first evacuated to a vacuum level ≤5×10⁻⁶. -3 The gas is charged with Ar (≥99.999% purity) as a protective and atomizing gas at a back-charging pressure of approximately 0.04 MPa. The Ta-8W pre-alloyed melt is heated to approximately 100°C above the liquidus and then atomized at an atomizing gas pressure of approximately 3.5 MPa to obtain spherical Ta-8W powder (D50 approximately 100 μm). Powder with a particle size of 20–100 μm is screened for subsequent processes (oxygen content approximately 400 ppm).

[0074] c) Nanocarbon mixing: Amorphous carbon powder with an average particle size of approximately 100 nm and multi-walled carbon nanotubes with an average outer diameter of approximately 30 nm were mixed in a 1:1 ratio as the carbon source. Before mixing, a two-dimensional boron nitride (h-BN) layer was coated on the surface of the nanocarbon material by chemical vapor deposition (CVD) and added to the Ta-8W powder at a mass fraction of approximately 1.0 wt.%. The mixed powder was placed in a ball mill jar filled with Ar gas, and an appropriate amount of anhydrous ethanol was added to control the ball-to-powder ratio at approximately 10:1. The mixture was ball-milled at 250 rpm for 4 h. After ball milling, the powder was vacuum dried at 60 °C for 12 h to obtain a uniform Ta-8W-1.0C composite powder.

[0075] d) Hot pressing sintering: The above composite powder is loaded into a circular graphite mold with a diameter of 210 mm and compacted, with a pressure of ≤5×10⁻⁶ mm. - 2 Heating under vacuum with an axial pressure of 32 MPa, the temperature was increased to 1250 °C at a rate of 50 °C / min and held for 2 hours. No external static magnetic field was applied during the entire sintering process. After sintering, the target blank was cooled to room temperature in the furnace and then removed.

[0076] e) Machining and Annealing: The sintered target blank is machined to its final dimensions (φ200mm × 8mm thickness), and the target surface roughness Ra is polished to <0.2μm. The resulting target material is then subjected to annealing at 900℃ under vacuum ≤1×10⁻⁶. -3 Annealing at Pa for 2 hours.

[0077] Performance Testing: EBSD pole figure analysis showed that no obvious (001) preferred orientation was formed in the normal direction of the target material, and its (001) texture enhancement coefficient was approximately 1.3. EDS surface scanning results showed that W element was evenly distributed in the cross-section and in-plane of the target material, with W content deviation in different test areas less than 3%. The relative density of the target material measured by the Archimedes method was approximately 98.9%. The nano-carbon reinforcing phase was mainly distributed near the grain boundaries, and no obvious large-size agglomerates were observed. Compared with Examples 1, 2, and 5, this comparative example showed that the grain directional growth and texture formation were significantly inhibited due to the absence of an external static magnetic field during sintering, resulting in a decrease in the target material's texture control ability, microstructure density, and stress buffering effect. This indicates that the external static magnetic field plays an important role in promoting the formation of (001) preferred orientation and improving the overall performance of the target material.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a tantalum-tungsten-based nanocomposite target, characterized in that, include: 1) High-purity tantalum blocks and high-purity tungsten blocks are melted and cast to obtain tantalum-tungsten pre-alloyed ingots; 2) The tantalum-tungsten pre-alloyed ingot is atomized and powdered to obtain Ta-W alloy powder; 3) The Ta-W alloy powder is mixed with nano-carbon materials to obtain TaW-C mixed powder; 4) The TaW-C mixed powder is subjected to magnetic field-assisted sintering to induce directional grain growth, followed by post-treatment to obtain tantalum-tungsten-based nanocomposite target material; the magnetic field-assisted sintering adopts a unidirectional static magnetic field along the direction perpendicular to the target surface, with a magnetic field strength of 2~10T.

2. The preparation method according to claim 1, characterized in that, In step 1), the tungsten content in the tantalum-tungsten pre-alloyed ingot is ≤12% by mass.

3. The preparation method according to claim 1, characterized in that, In step 1), the melting temperature is 2000~2500℃, the time is 10~100min, and the vacuum degree is ≤10. -3 Pa; And / or, the melting is vacuum induction melting, vacuum consumable arc melting, or electron beam melting; And / or, the tantalum-tungsten pre-alloy ingot is cylindrical with a diameter of 20~80mm.

4. The preparation method according to any one of claims 1-3, characterized in that, In step 2), the atomization powdering is performed by plasma rotating electrode atomization or high-pressure gas atomization; the particle size D50 of the Ta-W alloy powder is 50~150μm; And / or, in the Ta-W alloy powder, the mass fraction of powder with a particle size of 50~150μm is not less than 90%, and the oxygen content of the powder is ≤1000ppm.

5. The preparation method according to any one of claims 1-3, characterized in that, In step 3), the nano-carbon material includes one or more of amorphous carbon powder, multi-walled carbon nanotubes, and graphene; the particle size of the amorphous carbon powder is 0~200nm; the outer diameter of the multi-walled carbon nanotubes is 5~50nm and the length is 0.5~5μm; the thickness of the graphene is 1~20nm and the sheet diameter is 0.5~5μm. And / or, the nano-carbon material is mixed with Ta-W alloy powder and ball-milled; the mass of the nano-carbon material accounts for 0.01% to 1.0% of the mass of the Ta-W alloy powder; anhydrous ethanol is used as the dispersion medium, the ball-to-powder ratio is 5 to 15:1, the ball-milling time is 1 to 6 hours; a planetary ball mill is used for ball milling, and the ball milling speed is 200 to 300 rpm.

6. The preparation method according to claim 5, characterized in that, Step 3) also includes the step of surface modification or coating of the nano-carbon material; a ceramic material layer is coated on the surface of the nano-carbon material using chemical vapor deposition or atomic layer deposition, wherein the ceramic material layer is boron nitride.

7. The preparation method according to any one of claims 1-3, characterized in that, In step 4), the sintering temperature is 1000~1500℃ and the pressure is 25~35MPa; And / or, the holding time for sintering is 1~6h, the heating rate is 10~100℃ / min, and the sintering is carried out in a vacuum environment ≤10℃. -2 The process is carried out under a protective atmosphere or at a pressure of Pa.

8. The preparation method according to claim 7, characterized in that, In step 4), after sintering, the obtained target blank is subjected to medium-temperature vacuum annealing treatment at a temperature of 800~1000℃ for 1~4h.

9. The tantalum-tungsten based nanocomposite target obtained by the preparation method according to any one of claims 1-8.

10. The tantalum-tungsten based nanocomposite target according to claim 9, characterized in that, The relative density of the tantalum-tungsten based nanocomposite target is 99%~100%; the enhancement coefficient of the (001) crystal plane texture intensity perpendicular to the target surface direction relative to random polycrystalline is ≥2; and the tungsten content deviation in the tantalum-tungsten based nanocomposite target is ≤3%.

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