Preparation method of nanoscale densified tungsten-copper alloy

Abstract

The invention relates to a preparation method of a nanoscale densified tungsten-copper alloy, which comprises the following steps: performing chromium ion implantation on tungsten powder, and then spraying a copper-titanium composite layer to obtain modified tungsten powder; a certain mass of modified tungsten powder and copper powder are mixed through an ultrasonic-assisted double-planet mixer, and mixed powder is obtained; forming the mixed powder into a blank; and sintering the green body in vacuum to obtain the copper-tungsten alloy. The modified tungsten powder is subjected to chromium ion implantation to form a tungsten-chromium solid solution, so that the surface activity and diffusivity of tungsten are improved, the problem of poor intersolubility of tungsten and copper is solved, and metallurgical reaction active sites are provided; ti-W and Ti-Cu phases are formed by titanium in the copper-titanium composite layer, an interface transition layer is constructed, mechanical occlusion is converted into metallurgical bonding, the interface strength is enhanced, the wettability is improved, and liquid copper is assisted to fill gaps. The ultrasonic-assisted double-planet mixer breaks nano powder agglomeration and enhances powder contact through vibration, revolution and autorotation to realize uniform mixing, and is matched with a copper-titanium composite layer to reduce copper-tungsten interface energy and ensure uniform components.

Description

Technical Field

[0001] This application belongs to the field of powder metallurgy technology, and more specifically, relates to a method for preparing nanoscale densified tungsten-copper alloys. Background Technology

[0002] Tungsten-copper alloys, as a typical tungsten-based composite material, occupy an irreplaceable position in high-end manufacturing fields such as heat sink components for aerospace engines, heat dissipation modules for high-power electronic packaging, and shielding materials for the nuclear industry, thanks to the high melting point and high hardness of the tungsten phase and the excellent electrical and thermal conductivity of the copper phase.

[0003] Tungsten and copper have extremely poor interfacial miscibility. Pure tungsten has low surface atomic activity and a small diffusion coefficient, making it difficult for the tungsten-copper interface to form an effective metallurgical bond during sintering. Connection can only be achieved through mechanical interlocking, resulting in low interfacial bond strength and leaving numerous pores at the interface, significantly hindering the densification process of the alloy. Nanoscale tungsten powder (density approximately 19.3 g / cm³) and copper powder (density approximately 8.96 g / cm³) have a significant density difference, and the nanoparticles have extremely high surface energy and are prone to forming hard agglomerates. During mixing, segregation easily occurs—high-density tungsten powder tends to settle and agglomerate, while low-density copper powder tends to float and accumulate, leading to uneven distribution of the mixed powder components. The tiny gaps inside tungsten agglomerates become inherent pores that are difficult to eliminate after sintering. This is because tungsten has a melting point as high as 3410℃, which is much higher than the general sintering temperature. During sintering, it always maintains a solid particle form. Copper (melting point 1083.4℃) can melt into a liquid state during sintering. The liquid copper that should fill the gaps between tungsten particles is difficult to penetrate due to the dense structure of tungsten agglomerates. The tungsten particles can only be connected by weak mechanical interlocking, and the gaps cannot be closed, leaving a large number of gaps and pores. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing nanoscale densified tungsten-copper alloys, so as to solve the technical problem that it is difficult to achieve efficient densification of tungsten-copper alloys in the prior art.

[0005] To achieve the above objectives, the technical solution adopted in this application is: a method for preparing nanoscale densified tungsten-copper alloy, comprising the following steps: S1. Chromium ion implantation is performed on tungsten powder, followed by spraying a copper-titanium composite layer to obtain modified tungsten powder; S2. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer to obtain a mixed powder; S3. Mixed powder is molded into blanks; S4. Vacuum sintering of the billet yields a copper-tungsten alloy.

[0006] Optionally, the tungsten powder has a particle size of 50-200 nm and the copper powder has a particle size of 30-50 nm.

[0007] Optionally, in step S1, chromium ion implantation is performed on tungsten powder using an ion implanter, with chromium ion energy of 50-80 keV and a dose of 5 × 10⁻⁶. 15 ions / cm², vacuum degree <1×10 -4 Pa.

[0008] Optionally, the sprayed copper-titanium composite layer is prepared by atomic layer deposition with a thickness of 5-10 nm, the deposition temperature is 200-250℃, and argon is used as the purge gas. The copper-titanium composite layer contains 5% titanium by mass, with the remainder being copper.

[0009] Optionally, the modified tungsten powder and the copper powder account for 80% and 20% of the mass of the mixed powder, respectively.

[0010] Optionally, the ultrasonic-assisted dual planetary mixer is set to a revolution speed of 60-100 r / min, a rotation speed of 150-200 r / min, a mixing time of 60-90 min, an ultrasonic power of 100-200 W, and a frequency of 20-40 kHz.

[0011] Optionally, the mixed powder is formed into a blank by compression molding or metal injection molding.

[0012] Optionally, the pressing process is performed using powder metallurgy pressing equipment to press the mixed powder into shape.

[0013] Optionally, the metal injection molding process involves first feeding the mixed powder into an injection molding machine to obtain a blank, then degreasing it, and finally sintering it to obtain the finished product.

[0014] Optionally, the vacuum sintering is divided into three stages: the first stage is held at 400-600℃ for 30 minutes; the second stage is heated to 800-1000℃ and held for 60 minutes; the third stage is heated to 1100-1200℃ and held for 45 minutes.

[0015] The modified tungsten powder used in this application, after chromium ion implantation, forms a tungsten-chromium solid solution on the surface of the tungsten powder, which can improve the surface activity and atomic diffusion ability of the tungsten phase, solve the problem of poor miscibility with copper caused by the inertness of the pure tungsten surface reaction, and provide sufficient active sites for interfacial metallurgical reactions. In the outer copper-titanium composite layer, titanium can form Ti-W solid solution or intermetallic compound with tungsten and Ti-Cu intermetallic compound with copper respectively during sintering, constructing a stable tungsten-copper interface transition layer, transforming the mechanical interlocking interface into a metallurgical bonding interface, significantly enhancing the interfacial bonding strength, and greatly improving the wettability of liquid copper on the surface of modified tungsten powder, helping liquid copper to flow along the composite layer and penetrate into the tiny gaps between tungsten powder particles under capillary force.

[0016] The ultrasonic-assisted dual planetary mixer, through a combination of high-frequency vibration and rotation, not only effectively breaks down hard agglomerates of nanopowders due to their high surface energy, but also enhances the contact tightness between modified tungsten powder and copper powder with vibration energy, achieving uniform mixing at the nanoscale. At the same time, the copper-titanium composite layer on the surface of the modified tungsten powder reduces interfacial energy, effectively suppressing sedimentation / floating segregation caused by density differences, ensuring uniform distribution of the mixed powder components, and laying the foundation for reducing defects such as porosity and segregation in subsequent molding and sintering processes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a method for preparing nanoscale densified tungsten-copper alloys, as provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Tungsten-copper alloys, as a typical tungsten-based composite material, occupy an irreplaceable position in high-end manufacturing fields due to the high melting point and hardness of the tungsten phase and the excellent electrical and thermal conductivity of the copper phase. However, the interfacial miscibility between tungsten and copper is extremely poor. Pure tungsten has low surface atomic activity and a small diffusion coefficient, making it difficult to form an effective metallurgical bond at the tungsten-copper interface during sintering. Connection can only be achieved through mechanical interlocking, resulting in low interfacial bonding strength and a large number of pores remaining at the interface, significantly hindering the densification process of the alloy. Due to the significant density difference between nano-sized tungsten powder and copper powder, the tiny gaps within the tungsten agglomerates become inherent pores that are difficult to eliminate after sintering. While copper can melt into a liquid state during sintering, liquid copper cannot penetrate the dense structure of tungsten agglomerates. Tungsten particles can only be connected through weak mechanical interlocking, and the gaps cannot close, leaving a large number of interstitial pores.

[0021] Please see Figure 1 To address the aforementioned problems, this application provides a method for preparing nanoscale densified tungsten-copper alloy, comprising the following steps: S1. Chromium ion implantation is performed on tungsten powder, followed by spraying a copper-titanium composite layer to obtain modified tungsten powder; S2. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer to obtain a mixed powder; S3. Mixed powder is molded into blanks; S4. Vacuum sintering of the billet yields a copper-tungsten alloy.

[0022] It should be noted that both chromium and tungsten are body-centered cubic transition metals with similar atomic radii (tungsten 137 pm, chromium 128 pm). In step S1, chromium ions, after being injected with high energy into tungsten powder, can embed into the surface lattice of the tungsten powder, forming a tungsten-chromium solid solution. This solid solution disrupts the integrity of the atomic arrangement on the tungsten surface, introducing lattice distortion and defects (such as vacancies and dislocations), significantly improving the diffusion coefficient and chemical activity of tungsten surface atoms. This solves the problem of poor miscibility with copper caused by the reactive inertness of the pure tungsten surface, providing active sites for subsequent interfacial metallurgical reactions. Titanium is a highly reactive element. In the sprayed copper-titanium composite layer, during the vacuum sintering stage, titanium atoms gain sufficient kinetic energy to overcome the lattice barrier on the surface of the tungsten powder, rapidly migrating along defects or grain boundaries on the tungsten powder surface to form Ti-W solid solutions or intermetallic compounds (such as TiW) with tungsten, and Ti-Cu intermetallic compounds (such as TiCu, Ti2Cu) with copper. These transition phases effectively bridge tungsten and copper, transforming the mechanical interlocking interface of tungsten and copper into a metallurgical bonding interface, thus improving the interfacial bonding of tungsten and copper. Tungsten and copper are miscible, and there is no chemical reaction at the interface. The poor wettability of tungsten surface to liquid copper makes it difficult for liquid copper to spread on the tungsten surface, preventing it from penetrating the surface layer of tungsten agglomerates and into the internal gaps. After chromium ion implantation and spraying of a copper-titanium composite layer into tungsten powder, the liquid copper Ti-Cu layer fuses during sintering (due to its good compatibility) and flows along the composite layer on the surface of the modified tungsten powder. Driven by capillary force, it penetrates into the tiny gaps between tungsten powder particles through the interfacial gaps between the Ti-W phase and the W-Cr solid solution, filling the gaps that were originally closed by the dense agglomerates and reducing residual porosity.

[0023] Nano-tungsten powder, due to its high surface energy, easily forms hard agglomerates (multiple tungsten powders tightly bound together into large particles). These agglomerated tungsten aggregates have higher density and larger size, and are more significantly affected by gravity in the mixed system, settling much faster than dispersed single particles, thus being a major cause of segregation. Modification with a copper-titanium composite layer significantly reduces the surface energy of the modified tungsten powder (the surface energies of copper and titanium in the composite layer are lower than those of pure tungsten, and covering the tungsten powder surface reduces direct contact between tungsten particles), effectively inhibiting the hard agglomeration of the modified tungsten powder itself. The interfacial energy between tungsten powder and copper powder is extremely high, making them more prone to aggregation during mixing, further exacerbating segregation. However, the copper phase in the copper-titanium composite layer (with the same composition as copper powder) can significantly reduce the interfacial energy between the modified tungsten powder and copper powder. Atoms on the copper powder surface will form affinity contacts with copper atoms in the composite layer through diffusion or physical adsorption, meaning that copper powder is more easily attached to the surface of the modified tungsten powder. Therefore, modified tungsten powder can effectively suppress the sedimentation / floating segregation of nanoparticles caused by density differences, while reducing the hard agglomeration of tungsten powder itself, ensuring the uniform distribution of the mixed powder components. In step S2, the ultrasonic-assisted dual planetary mixer achieves large-scale powder tumbling through the coordinated motion of revolution and rotation. At the same time, ultrasonic vibration breaks up the agglomerates of tungsten and copper powder to avoid local enrichment caused by density and particle size differences. The vibration energy of ultrasound enhances the contact tightness between the copper-titanium composite layer on the surface of the modified tungsten powder and the copper powder, and also improves the flowability of the mixed powder to reduce defects such as porosity and segregation inside the formed blank. This significantly improves the powder mixing uniformity and lays the foundation for subsequent forming and alloy densification and high interfacial bonding strength.

[0024] Step S3 involves pressing the uniformly mixed powder into a blank with a predetermined shape (such as a block or irregular part) and a certain initial strength through a molding process. This initially fixes the arrangement structure of the powder particles, providing a stable matrix morphology for the subsequent sintering process and reducing deformation and collapse during sintering.

[0025] Step S4 promotes the diffusion, fusion, and densification of powder particles in a vacuum environment by using high temperature (usually the melting point of copper) to eliminate internal pores in the blank. At the same time, the vacuum environment can prevent the oxidation of tungsten, copper, and modified layers (such as titanium), and can also promote interfacial reactions (such as titanium forming a reinforcing phase with tungsten and copper), ultimately forming a nanoscale dense tungsten-copper alloy with high interfacial bonding strength.

[0026] In another embodiment of this application, the tungsten powder has a particle size of 50-200 nm and the copper powder has a particle size of 30-50 nm.

[0027] It should be noted that tungsten powder with a particle size of 50-200nm is combined with copper powder with a particle size of 30-50nm. The smaller copper powder can fill the gaps between the tungsten powder particles, effectively reducing the internal porosity of the material and improving the density. The tungsten powder with a moderate particle size can retain the high strength properties required by the material and reduce the agglomeration that is easily caused by excessively small particle size to a certain extent. At the same time, this particle size combination reduces porosity and reduces the diffusion resistance during the sintering stage. The larger specific surface area of ​​copper powder results in more contact points between the copper and tungsten powder particles, shortening the molding cycle and ensuring the dimensional stability of the product.

[0028] In another embodiment of this application, in step S1, chromium ions are implanted into tungsten powder using an ion implanter, with an ion energy of 50-80 keV and a dose of 5 × 10⁻⁶ keV. 15 ions / cm², vacuum degree <1×10 -4 Pa.

[0029] It should be noted that chromium ion implantation into the surface of tungsten powder forms a doped layer, which reduces the interfacial energy between tungsten and copper, decreases elemental segregation during sintering, and allows for a tighter bond between the two powders. A chromium ion energy of 50-80 keV allows chromium ions to effectively penetrate the surface of the tungsten powder (rather than merely adhering to the surface) without damaging the internal structure of the tungsten powder particles due to excessive energy. The chromium ion implantation dose is 5 × 10⁻⁶. 15 The ions / cm² concentration ensures sufficient chromium content on the surface to form a continuous doped layer, meeting the requirements for interface strengthening and oxidation resistance. Insufficient dosage will result in insignificant effects. Vacuum degree < 1 × 10⁻⁶ -4 Chromium ion implantation is performed in an environment of Pa to avoid the reaction between impurities such as oxygen and nitrogen in the air and chromium ions or tungsten powder, thus ensuring the purity of the implantation process and the uniformity of chromium ion distribution.

[0030] In another embodiment of this application, the sprayed copper-titanium composite layer is prepared by atomic layer deposition with a thickness of 5-10 nm, the deposition temperature is 200-250 °C, and argon is used as the purge gas. The copper-titanium composite layer contains 5% titanium by mass, with the remainder being copper.

[0031] It should be noted that atomic layer deposition (ALD) is a technique for precisely fabricating nanoscale conformal thin films on substrate surfaces through alternating pulsed introduction of precursors and based on self-limiting surface reactions. Argon, as an inert gas, effectively removes unreacted precursors and byproducts remaining in the reaction chamber during ALD, preventing impurities from adsorbing onto the tungsten powder surface and affecting the purity of the composite layer. It also prevents oxidation reactions between tungsten powder and gases such as oxygen at high temperatures, ensuring the uniformity of composition and the density of the copper-titanium composite layer. The deposition temperature of 200-250℃ ensures sufficient decomposition of the precursor and the formation of a stable film while preventing oxidation of the tungsten powder surface or abnormal grain growth due to excessive temperature, thus reserving sufficient activity for the interfacial reactions in the subsequent sintering stage. A 5-10 nm copper-titanium composite layer is suitable for the 50-200 nm nanoscale of tungsten powder. This thickness can cover the nanoscale roughness of the tungsten powder surface, forming a continuous, non-porous coating layer, avoiding weak interfacial bonding due to coating discontinuity. It also avoids the problem of excessive thickness hindering the cross-interfacial diffusion of tungsten and copper atoms during subsequent sintering, or insufficient thickness failing to construct an effective reaction interface. The mass ratio of the copper-titanium composite layer is set at 5% titanium and 95% copper. Titanium, as an active element, can form stable intermetallic compounds with the matrix and copper layer, significantly improving interfacial bonding and preventing detachment. Copper retains excellent electrical and thermal conductivity and utilizes its ductility to alleviate internal stress during spraying, preventing cracking of the composite layer. This ratio simultaneously avoids the problems of increased brittleness due to excessive titanium content and insufficient titanium content to form an effective bonding interface.

[0032] In another embodiment of this application, the modified tungsten powder and the copper powder account for 80% and 20% of the mass of the mixed powder, respectively.

[0033] It should be noted that the 80% high proportion of modified tungsten powder serves as the core matrix of the alloy. Leveraging tungsten's excellent high-temperature stability, high strength, and high hardness, it provides a solid structural foundation for the prepared alloy. This not only effectively resists mechanical wear, deformation, and high-temperature impact during use, ensuring the structural integrity of the material under complex working conditions and meeting the stringent requirements for load-bearing strength and rigidity in applications, but also further enhances the matrix's density and anti-aging capabilities through the advantages of pre-modification treatment. The 20% copper powder serves as a functional filler phase. Its proportion is optimized to ensure sufficient filling of the gaps between tungsten powder particles during mixing and sintering, eliminating internal porosity and improving alloy density. It also forms a continuous and complete conductive and thermally conductive network. Because copper itself possesses excellent electrical and thermal conductivity, the continuous phase structure allows for rapid electron and heat transfer, avoiding performance shortcomings caused by discontinuous conductive and thermally conductive channels. Simultaneously, this proportion will not dilute the tungsten powder matrix strength due to excessive copper powder, nor will insufficient copper powder lead to inadequate filling or functional network breakage.

[0034] In another embodiment of this application, the ultrasonic-assisted dual planetary mixer is set to a revolution speed of 60-100 r / min, a rotation speed of 150-200 r / min, a mixing time of 60-90 min, an ultrasonic power of 100-200 W, and a frequency of 20-40 kHz.

[0035] It should be noted that the planetary mixer's revolution speed is controlled at 60-100 r / min, providing sufficient overall driving force for powder mixing. This ensures efficient convection circulation between tungsten and copper powders within the mixing chamber, preventing localized material accumulation. The rotation speed is set at 150-200 r / min, allowing the stirring paddles to shear and disperse the material, breaking up agglomerated powder particles and promoting uniform mixing of the two powders. The 60-90 min mixing time design ensures sufficient contact and diffusion between powder particles under gentle mixing, achieving component homogenization, while avoiding excessive oxidation or mechanical damage due to excessive mixing time. The combination of 100-200W ultrasonic power and a 20-40kHz frequency utilizes the cavitation effect and mechanical vibration of ultrasound to further break down adsorbed gases and impurities on the powder surface, enhancing interfacial wettability between particles and creating favorable conditions for densification and interfacial bonding during subsequent sintering. Within this parameter range, the mixed composite powder not only has ideal mixing uniformity, but its particle morphology and surface condition can also meet the strict requirements of subsequent molding and sintering processes, effectively improving the comprehensive performance of tungsten-copper alloys.

[0036] In another embodiment of this application, the mixed powder is formed into a blank by compression molding or metal injection molding.

[0037] It should be noted that compression molding involves applying pressure to a mixed powder, causing the powder particles to shift, deform, and interlock under pressure, thus forming a blank with a specific shape and strength. This process is simple to operate, highly efficient, and suitable for preparing blanks with relatively simple shapes. Metal injection molding, on the other hand, involves uniformly mixing a mixed powder with a binder to create a feedstock, which is then injected into a mold cavity using an injection molding machine. Debinding and sintering follow the process. This process can achieve near-net-shape forming of complex-shaped blanks, effectively reducing subsequent machining allowances and improving material utilization. It is particularly suitable for preparing parts with intricate structures and complex contours. In actual production, the appropriate molding process can be selected based on factors such as the shape complexity of the blank, dimensional accuracy requirements, and production volume to ensure that the blank quality meets the requirements of subsequent sintering and application.

[0038] In another embodiment of this application, the pressing molding is performed by using powder metallurgy pressing molding equipment to press the mixed powder into shape.

[0039] It should be noted that the mixed powder is pressurized and formed using a publicly disclosed patented device (corresponding patent publication number: CN119387588A; patent name: A powder metallurgy pressurization forming device and forming method). The structure and working principle of this device have been disclosed in detail in the aforementioned patent, and will not be repeated here. During the pressurization process, the mixed powder particles come into close contact under pressure, expelling air between the particles, reducing porosity during subsequent sintering, and improving the density and structural stability of the alloy product. At the same time, pressurization can quickly impart a pre-set blank shape to the mixed powder, ensuring the initial consistency of the blank size and reducing the difficulty of subsequent processing. The pressurization process is simple to operate, has high forming efficiency, is suitable for mass production, and can retain the uniform distribution of tungsten and copper powder in the mixed powder to the greatest extent, avoiding powder stratification and ensuring the uniformity of the mechanical and functional properties of the alloy after subsequent sintering.

[0040] In another embodiment of this application, the metal injection molding process involves first feeding the mixed powder into an injection molding machine to obtain a blank, then degreasing it, and finally sintering it to obtain the finished product.

[0041] It should be noted that the finished product is manufactured using a metal injection molding process involving injection molding, debinding, and sintering, which is suitable for molding complex shapes. The mixed powder is incorporated into the binder using our company's publicly disclosed patented equipment (corresponding patent publication number: CN216267216U; patent name: An injection molding machine for easy material handling), and then demolded. The structure and working principle of this equipment have been disclosed in detail in the aforementioned patents and will not be repeated here. The injection molding method can accurately replicate the preset structure, resulting in small dimensional tolerances and high shape accuracy of the blank, meeting the assembly and use requirements of high-precision parts. The addition of binder not only improves the fluidity of the mixed powder, making the injection process smoother and ensuring that complex cavities are fully filled by the powder, but also prevents the powder from layering or agglomerating during the molding process, ensuring uniform composition in all parts of the blank. Subsequent degreasing treatment can completely remove the binder from the blank, avoiding impurities, pores, or cracks caused by binder decomposition during the sintering stage. Combined with the sintering process, it can promote the full diffusion and tight bonding of powder particles, significantly improving the density, mechanical strength, and structural stability of the finished product, while retaining the material's excellent electrical and thermal conductivity. In addition, the patented injection molding machine has a built-in design that facilitates material unloading, reducing mechanical damage to the blank during demolding and further improving the yield. Moreover, the entire process is highly automated and adaptable, enabling continuous mass production. This effectively ensures the performance consistency of large-volume products and reduces the time and labor costs of large-scale manufacturing, adapting to the needs of industrial applications.

[0042] In another embodiment of this application, the vacuum sintering is divided into three stages: the first stage is held at 400-600℃ for 30 minutes; the second stage is heated to 800-1000℃ and held for 60 minutes; and the third stage is heated to 1100-1200℃ and held for 45 minutes. It should be noted that the first stage, a low-temperature holding at 400-600℃ for 30 minutes, can gently remove adsorbed moisture and trace impurities from the billet, as well as residual binders in the billet obtained from the metal injection molding process. This prevents the rapid decomposition of impurities and the generation of gas during the subsequent high-temperature stage, which could lead to porosity or cracks in the finished product. The second stage, a medium-temperature holding at 800-1000℃ for 60 minutes, reaches the copper powder diffusion activation energy range to promote the diffusion of copper powder into the gaps between tungsten powders, achieving initial densification. It also slowly releases the internal stress accumulated in the billet during the molding and degreasing stages, preventing cracking caused by stress concentration under subsequent high temperature and high pressure. The third stage, a high temperature holding at 1100-1200℃ for 45 minutes, can significantly increase the diffusion rate of tungsten and copper atoms, forcing the particles to adhere tightly to completely eliminate residual porosity, while strengthening the interfacial metallurgical bond between tungsten and copper.

[0043] The present invention will be further illustrated below through specific embodiments: Example 1 S1. The particle size of tungsten powder is selected as 100 nm, and the particle size of copper powder is selected as 50 nm. Chromium ion implantation is performed on the tungsten powder using an ion implanter with an energy of 50 keV and a dose of 5 × 10⁻⁶ kilometres per second. 15 ions / cm², vacuum degree <1×10 -4 Pa. A copper-titanium composite layer with a thickness of 8 nm was then sprayed onto the surface using atomic layer deposition at a temperature of 200℃, with argon as the purge gas. The mass fraction of titanium in the copper-titanium composite layer was 5%, with the remainder being copper. Finally, modified tungsten powder was obtained.

[0044] S2, the mass proportions of modified tungsten powder and copper powder in the mixed powder are 80% and 20%, respectively. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer with the rotation speed set to 100 r / min for revolution and 150 r / min for rotation, the mixing time to 60 min, the ultrasonic power to 150 W, and the frequency to 30 kHz, to obtain the mixed powder.

[0045] S3. The mixed powder is pressed and molded using powder metallurgy pressure molding equipment to produce blanks.

[0046] S4. Vacuum sinter the billet to obtain a copper-tungsten alloy. The first stage is held at 500℃ for 30 minutes; the second stage is heated to 900℃ and held for 60 minutes; the third stage is heated to 1100℃ and held for 45 minutes.

[0047] Example 2 S1. The specific steps are the same as in Example 1, except that the particle size of the tungsten powder is 150nm, the particle size of the copper powder is 50nm, and the thickness of the copper-titanium composite layer is 9nm.

[0048] S2. The specific steps are the same as in Example 1. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer. The rotation speed is set to 80 r / min for revolution and 160 r / min for rotation. The mixing time is 70 min, the ultrasonic power is 180 W, and the frequency is 35 kHz to obtain mixed powder.

[0049] S3. The specific steps are the same as in Example 1.

[0050] S4. Vacuum sinter the billet to obtain a copper-tungsten alloy. The first stage is held at 500℃ for 30 minutes; the second stage is heated to 950℃ and held for 60 minutes; the third stage is heated to 1150℃ and held for 45 minutes.

[0051] Example 3 S1. The specific steps are the same as in Example 1, except that the particle size of the tungsten powder is 200 nm, the particle size of the copper powder is 50 nm, and the thickness of the copper-titanium composite layer is 10 nm.

[0052] S2. The specific steps are the same as in Example 1. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer. The rotation speed is set to 80 r / min for revolution and 200 r / min for rotation. The mixing time is 60 min, the ultrasonic power is 200 W, and the frequency is 40 kHz to obtain mixed powder.

[0053] S3. The specific steps are the same as in Example 1.

[0054] S4. Vacuum sinter the billet to obtain a copper-tungsten alloy. The first stage is held at 550℃ for 30 minutes; the second stage is heated to 1000℃ and held for 60 minutes; the third stage is heated to 1200℃ and held for 45 minutes.

[0055] Comparative Example 1: The difference between this comparative example and Example 1 is that tungsten copper alloy was prepared by mixing tungsten powder and copper powder without modification.

[0056] Density (porosity) test Test Principle: Based on Archimedes' displacement method, the actual volume of the sample (displaced liquid volume) is calculated by measuring the mass of the sample in air (m1) and the mass of the sample completely submerged in the test liquid (m2). This difference in mass is then combined with the material's theoretical density (ρ). t The formulas for deriving bulk density (ρ) and total porosity (P) are as follows: In Examples 1 / 2 / 3, the thickness of the copper-titanium composite layer is (8nm / 9nm / 10nm), assuming that the tungsten powder is spherical and the particle size of the tungsten powder is (100nm / 150nm / 200nm), the theoretical density of tungsten is 19.3g / cm³, the theoretical density of titanium is 4.51g / cm³, and the theoretical density of copper is 8.96g / cm³. v 钨 =4πr 3 / 3、v 铜-钛 =4π[(r+t) 3 -r 3 ] / 3; m 钨 =v 钨 ·ρ 钨 m 铜-钛 =v 铜-钛 · (95%ρ) 铜 +5%ρ 钛 ); ρ 改性钨粉 =(m 钨 +m 铜-钛 ) / (v 钨 +v 铜-钛 ); ρ t =1 / (0.8 / ρ 改性钨粉 +0.2 / ρ 铜 ); Comparative Example 1 uses ρ 钨粉 =19.3g / cm³, assuming the total mass is 1g, ρ t1 =1g / (0.8g / ρ 钨粉 +0.2g / ρ 铜 =15.68 g / cm³; The bulk density (ρ) of a material is calculated using the following formula: ρ = m1 / m1 - m2 × ρ 液 ; Total porosity P is calculated using the following formula: P = (1 − ρ / ρ t (ρ) × 100%. (The lower the porosity, the better the densification effect), from which we can obtain the density = (ρ / ρ) × 100%. t )×100%.

[0057] v_tungsten is the volume of tungsten powder (cm³), v_tungsten 铜-钛 Let r be the volume of the copper-titanium composite layer (cm³), r be the radius of the tungsten powder (cm), t be the thickness of the copper-titanium composite layer (cm), ρ be the density of the modified tungsten powder (g / cm³), and m be the density of the modified tungsten powder. 钨 The mass (g) of tungsten powder, m 铜-钛 The mass (g) of the copper-titanium composite layer ρ t The theoretical density (g / cm³) and ρ of the samples in Examples 1-3 are given.t1 The theoretical density (g / cm³) of the sample in Comparative Example 1, m1 is the mass (g) of each sample in air, and m2 is the mass (g) of each sample completely immersed in the test liquid. Test standard: GB / T 3850-2015.

[0058] Instruments and materials: electronic precision balance (accurate to 0.001g), suspension wire, transparent container (for holding test liquid), vacuum drying oven.

[0059] Test liquid: 20℃ deionized water, with 2 drops of wetting agent (Tween 80) added to the test liquid.

[0060] Test samples: One sample each from the surface and the interior of each laser-cut sample was taken, with a sample weight of 10.000g. The sample surface was polished with metallographic sandpaper, ultrasonically cleaned with anhydrous ethanol for 5 minutes, placed in a vacuum drying oven, kept at 80℃ for 2 hours, and then quickly transferred to a vacuum drying oven for later use after cooling to room temperature.

[0061] Test Procedure: Remove the sample from the vacuum drying oven and place it on an electronic precision balance. Quickly weigh the sample in air (recorded as m1), accurate to 0.001g. Suspend the sample in the liquid using a wire (ensuring each sample is completely submerged and does not touch the container wall / bottom, with no air bubbles adhering). Weigh the sample in the liquid (recorded as m2), accurate to 0.001g. Simultaneously measure the temperature of the liquid during the test and find the density of the liquid at that temperature (recorded as ρ). 液 ).

[0062] Table 1. Data related to porosity testing Table 1 shows that the tungsten-copper alloys prepared from modified tungsten powder and copper powder using chromium ion implantation and copper-titanium composite layer coating in Examples 1-3 exhibit surface and internal densities both exceeding 95%, demonstrating significant overall densification. In contrast, Comparative Example 1, without tungsten powder modification, shows surface and internal densities of only 80.9% and 84.5%, respectively, far lower than Examples 1-3. This indicates that modifying tungsten powder through chromium ion implantation and copper-titanium composite layer coating effectively improves the density and reduces porosity of tungsten-copper alloys. Chromium ion implantation improves the physicochemical properties of the tungsten powder surface; the copper-titanium composite layer forms a uniform transition layer on the tungsten powder surface, promoting copper atom diffusion and thus enhancing the alloy's density and structural stability.

[0063] In summary, the method for preparing nanoscale densified tungsten-copper alloy provided in this application can significantly improve the density of tungsten-copper alloy through modification of tungsten powder and optimized forming and sintering processes, laying a solid foundation for its application in high-precision and high-performance fields.

[0064] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing nanoscale densified tungsten-copper alloy, characterized in that, Includes the following steps: S1. Chromium ion implantation is performed on tungsten powder, followed by spraying a copper-titanium composite layer to obtain modified tungsten powder; S2. A certain mass of modified tungsten powder and copper powder are mixed using an ultrasonic-assisted double planetary mixer to obtain a mixed powder; S3. Mixed powder is molded into blanks; S4. Vacuum sintering of the billet yields a copper-tungsten alloy.

2. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The tungsten powder has a particle size of 50-200 nm, and the copper powder has a particle size of 30-50 nm.

3. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, In step S1, chromium ions are implanted into tungsten powder using an ion implanter. The chromium ion energy is 50-80 keV, and the dose is 5 × 10⁻⁶. 15 ions / cm², vacuum degree <1×10 -4 Pa.

4. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The sprayed copper-titanium composite layer is prepared by atomic layer deposition with a thickness of 5-10 nm, the deposition temperature is 200-250℃, and argon is used as the purge gas. The copper-titanium composite layer contains 5% titanium by mass, with the remainder being copper.

5. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The modified tungsten powder and the copper powder account for 80% and 20% of the mass of the mixed powder, respectively.

6. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The ultrasonic-assisted dual planetary mixer is set to a revolution speed of 60-100 r / min, a rotation speed of 150-200 r / min, a mixing time of 60-90 min, an ultrasonic power of 100-200 W, and a frequency of 20-40 kHz.

7. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The mixed powder is formed into blanks by compression molding or metal injection molding.

8. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 7, characterized in that, The pressing and molding process uses powder metallurgy pressing equipment to press and mold the mixed powders.

9. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 7, characterized in that, The metal injection molding process involves first feeding the mixed powder into an injection molding machine to form a blank, then degreasing it, and finally sintering it to obtain the finished product.

10. The method for preparing nanoscale densified tungsten-copper alloy as described in claim 1, characterized in that, The vacuum sintering process is divided into three stages: the first stage is held at 400-600℃ for 30 minutes; the second stage is heated to 800-1000℃ and held for 60 minutes; and the third stage is heated to 1100-1200℃ and held for 45 minutes.

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