Method for enhancing strength of copper-tungsten-copper-chromium alloy infiltration bonding surface through second-phase nickel

Abstract

The invention relates to the technical field of copper-tungsten-copper-chromium alloy, in particular to a method for enhancing the strength of a copper-tungsten-copper-chromium alloy infiltration bonding surface through second-phase nickel, which comprises the following steps: S1, proportioning: proportioning a copper-chromium alloy bar and a framework material according to the mass ratio of (11-12): 36; wherein the framework material comprises tungsten powder and nickel powder in a mass ratio of 100: (0.1-0.5); s2, ball milling; s3, preparing a tungsten-nickel composite framework; s4, infiltration is carried out; by precisely adding the second-phase nickel and regulating the content of the second-phase nickel, on one hand, the strength of the infiltration bonding surface of the copper-tungsten alloy and the copper-chromium alloy is remarkably improved, and the technical problem that the strength of the bonding surface is insufficient in an existing infiltration process is solved; and on the other hand, the segregation phenomenon of the chromium element at the infiltration bonding surface is effectively inhibited, microdefects caused by segregation are reduced, then the quality stability and reliability of the copper-tungsten-copper-chromium alloy are improved, and the risk of cracking of the bonding surface is reduced.

Description

Technical Field

[0001] This invention relates to the field of copper-tungsten-copper-chromium alloy technology, specifically to a method for strengthening the bonding strength of the copper-tungsten-copper-chromium alloy melt-infiltration interface with second-phase nickel. Background Technology

[0002] The melt infiltration method involves pressing tungsten powder into a blank, pre-firing it at a certain temperature to prepare a porous tungsten matrix framework with a certain density and strength, and then melting and infiltrating the tungsten framework with chromium and copper metals with lower melting points to obtain a denser tungsten-copper material.

[0003] Existing techniques for melting copper-chromium alloys into a copper-tungsten 80 (W80Cu20) framework are limited by the solid solution properties of chromium in copper—its equilibrium maximum solubility in copper is only 0.65%~0.7% (mass fraction). When the chromium content in the melting system exceeds this threshold, excess chromium atoms are difficult to dissolve uniformly in the copper matrix and tend to accumulate and segregate at the interface between the copper-tungsten framework and the copper-chromium alloy. This segregation disrupts the compositional homogeneity at the interface, hindering the full penetration of the molten copper-chromium alloy into the pores of the copper-tungsten framework, leading to incomplete melting and poor melting, such as localized porosity. Furthermore, the chromium-rich phase formed by segregation lacks effective metallurgical bonding with the copper-tungsten matrix, making the interface a weak point in mechanical properties. Ultimately, this results in a significant reduction in the tensile strength of the bonding surface, posing a quality risk of interface cracking under stress. Current melting infiltration processes utilize molybdenum wire furnaces, whose protective atmosphere consists solely of nitrogen, which cannot completely isolate residual oxygen within the furnace. Chromium, a typical oxophilic element, readily reacts with residual oxygen in the furnace or trace amounts of oxygen in the copper matrix at melting infiltration temperatures (typically ≥1000℃) to form chromium oxide (Cr2O3, etc.). Mechanical peel tests on the bonding surfaces of melt-infiltrated samples, combined with scanning electron microscopy (SEM) observation, revealed the presence of a distinct chromium oxide phase at the peeled bonding surfaces. This chromium oxide phase is a brittle compound that cannot effectively bond with the copper-tungsten framework or copper-chromium alloy, and it also blocks the metallurgical bonding pathway at the interface, leading to a significant decrease in interfacial bonding strength. Ultimately, this results in quality problems such as low tensile strength and easy delamination at the bonding surface.

[0004] Therefore, this application proposes a second-phase nickel-controlled copper-tungsten-copper-chromium melting infiltration preparation scheme to improve the above-mentioned problems. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for strengthening the bonding strength of copper-tungsten-copper-chromium alloys through second-phase nickel infiltration.

[0006] A method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with a second-phase nickel infiltration layer, characterized by comprising the following steps: S1, Ingredients The copper-chromium alloy bars and the skeleton material are mixed in a mass ratio of 11~12:36; The skeleton material includes tungsten powder and nickel powder in a mass ratio of 100:0.1~0.5, wherein the particle size of the tungsten powder is 6~8 μm and the particle size of the nickel powder is 0.1~0.3 μm; S2, ball mill Tungsten powder and nickel powder are first ball-milled and mixed to obtain the framework material; S3. Preparation of tungsten-nickel composite framework The skeleton material obtained in S2 is then pressed into a blank. The billet is placed in a vacuum furnace, and a vacuum is drawn until the furnace pressure is <100 Pa. Then, inert gas is introduced until the filling pressure reaches 1.02 × 10⁻⁶ Pa. 5 At Pa, a step-by-step sintering process is then performed to obtain a tungsten-nickel composite framework; S4, Melting Infiltration The copper-chromium alloy rod is placed on top of the tungsten-nickel composite skeleton and then placed together into the vacuum furnace. The vacuum degree inside the furnace is ≤6×10⁻⁶. -1 At Pa, a stepped melting process is carried out to obtain a copper-tungsten-copper-chromium alloy.

[0007] Furthermore, the nickel powder is T255 hydroxy nickel powder.

[0008] Note: The main component of T255 nickel hydroxyl powder is Ni(OH)2. After reduction, the Ni purity is ≥99.9%, exhibiting advantages of high activity and low impurities. The reduced nickel powder is nano-sized with a large specific surface area (≥15m²). 2 / g), which can be uniformly attached to the surface of tungsten powder during the mixing process (forming a "core-shell" structure), solves the problem of uneven dispersion of nickel powder under low proportion; at the same time, the impurity content is extremely low (C≤0.01%, S≤0.005%), avoiding the formation of brittle phases (such as Ni3C, NiS) by impurities in ordinary nickel powder, and ensuring the cleanliness of the bonding interface.

[0009] Furthermore, the copper-chromium alloy bar is a CuCr1 bar.

[0010] Note: CuCr1 bar stock can reduce problems such as poor melting and penetration caused by material deviations, thereby improving the bonding strength of copper, tungsten and nickel.

[0011] Furthermore, in S2, the ball mill uses 304 stainless steel as the ball milling material, the ball-to-material ratio is 3:1, the ball milling speed is 40~60Hz, and the ball milling time is 9.5~10.5h.

[0012] Note: The above ball-to-powder ratio can balance powder mixing efficiency and powder protection, and is suitable for uniform dispersion requirements with low nickel content. If the rotation speed is too low, the material movement is insufficient, and nickel powder is prone to deposit at the bottom of the tank, forming a "local nickel-rich area". If the rotation speed is too high, the material is prone to adhere to the tank wall due to centrifugal force, which reduces the collision between particles and may cause violent friction between the grinding balls and the tank wall, introducing impurities. This ensures the uniformity of trace nickel powder throughout the entire range and solves the diffusion problem of low addition amount.

[0013] Furthermore, in S3, the stepped sintering method is as follows: first, the temperature is increased to 590-610℃ at a rate of 4-6℃ / min, then the temperature is transferred to vacuum, with a vacuum degree ≤6×10⁻⁶. -1 Pa, continue to heat to 1300~1350℃ at 2~4℃ / min, and hold for 1.5~2.5h. After holding, cool to room temperature with the furnace, and the stepped sintering is completed.

[0014] Note: The above-mentioned stepped sintering method can promote the formation of sintering necks between tungsten particles, improve the strength of the skeleton, and thus enhance the bonding strength between the subsequent tungsten-nickel composite skeleton and the copper-chromium alloy.

[0015] Further, in S4, the stepped melt infiltration method is as follows: first, the temperature is raised to 1345-1355℃ at a rate of 3-5℃ / min, held for 3-4 hours, then the temperature is lowered to 690-710℃ at a rate of 1-3℃ / min, and then inert gas is introduced until the gas pressure reaches 1.02×10⁻⁶. 5 Pa, continue cooling to room temperature, and the step-by-step melting infiltration is completed.

[0016] Note: If the melting temperature is too low, the copper-chromium alloy will lack fluidity and fail to fill the pores. If it is too high, it will easily lead to coarse tungsten particles, affecting the product strength. If the holding time is too low, insufficient melting will occur. If it is too high, component segregation will easily occur. Therefore, the above parameter range can ensure that the copper-chromium alloy completely fills the pores of the tungsten framework.

[0017] Furthermore, before performing S4, the bonding surfaces of the copper-chromium alloy are first subjected to surface treatment. The surface treatment method is as follows: First, femtosecond laser etching is performed on the bonding surface of the copper-chromium alloy, followed by nanosecond laser processing, to obtain a copper-chromium alloy with an abalone shell-like gradient structure on the surface. The femtosecond laser etching has a wavelength of 1064nm, a pulse width of 5ps~12ps, a power of 25~45W, a scanning speed of 0.2~1.2m / s, and a scanning spacing of 50~150μm. The nanosecond laser processing has a wavelength of 265nm, a power of 10~30W, a frequency of 50~70kHz, a scanning speed of 500~1500mm / s, a unit feed rate of 50~60μm, and a unit feed depth of 20~60μm. The copper-chromium alloy with the abalone shell-like gradient structure is then vacuum impregnated in an impregnation solution at a solid-liquid ratio of 1g:20~30ml to obtain the vacuum-impregnated copper-chromium alloy. After being vacuum impregnated, the copper-chromium alloy is washed, dried, and then calcined in an inert atmosphere. The calcination heating rate is 5~10℃ / min, the temperature is 350~450℃, and the holding time is 1.5~2.5h. After calcination, a mixed gas is introduced and the temperature is lowered to 200~300℃ for activation for 2~3h. The mixed gas is hydrogen fluoride and nitrogen in a mass ratio of 1:1~1.5, to obtain a surface-treated copper-chromium alloy.

[0018] Explanation: Femtosecond laser pulses have extremely short durations and primarily involve nonlinear multiphoton absorption and cold processing, thereby etching deep and narrow micropores on the material surface with extremely high precision. This lays the foundation for the substrate structure of subsequent nanosecond laser processing. Then, a hierarchical structure is constructed through nanosecond laser processing, and its thermal effect is used to further modify and expand the microstructure manufactured by the femtosecond laser. On the one hand, it removes the small amount of slag generated by femtosecond laser processing, and on the other hand, it generates submicron-level rough textures on the existing micron structure, forming a micro / nano composite structure. This greatly increases the specific surface area, constructs multi-level roughness, and thus forms a hierarchical structure, which is beneficial for the penetration and spreading of the subsequent impregnation solution. Active chemical components are then introduced into the abalone-shell-like surface structure through vacuum impregnation. Impregnation in a vacuum environment eliminates air from the micropores, prevents bubble residue, and ensures complete solution filling, resulting in a dense, defect-free composite coating. Subsequent calcination provides energy to copper, chromium, and tungsten atoms, causing them to diffuse into each other at the interface. Furthermore, rapid laser surface melting and solidification treatment can form a dense, fine, hardened grain layer on the copper-based alloy surface, achieving surface nano-sizing and significantly improving its overall performance. HF effectively etches and removes the oxide film on the metal surface, exposing more active metal surfaces, greatly promoting atomic-level contact and diffusion between tungsten, nickel, chromium, and copper, making it easier to form a strong metallurgical bonding interface. This allows for a gradient transition from copper-chromium alloy to tungsten-nickel alloy at the interface, improving the bonding strength of the material.

[0019] Furthermore, the method for preparing the impregnation solution is as follows: Secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonyl betaine were added to a 10-20% (w / w) dilute hydrochloric acid solution and stirred at 25-30°C and 350-400 rpm for 35-45 min to obtain a precursor solution. The mass ratio of secondary alcohol polyoxyethylene ether to cocamidopropyl hydroxysulfonyl betaine is 1:1~2, and the solid-liquid ratio of secondary alcohol polyoxyethylene ether to dilute hydrochloric acid solution is 1g:20~25ml. Ammonium metatungstate and chromium nitrate were added sequentially to the precursor solution, and the solution was heated in a water bath at 65-85°C while being stirred at 550-650 rpm for 1-2 hours to obtain the impregnation solution. The mass ratio of ammonium metatungstate to chromium nitrate is 2-3:1, and the solid-liquid ratio of chromium nitrate to the precursor solution is 1g:25-30ml.

[0020] Explanation: The combination of secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonate betaine can significantly reduce the surface tension of the impregnation solution, allowing it to quickly and completely penetrate every corner of the complex micro-nano structure generated by laser etching, ensuring uniform distribution of active components. Ammonium metatungstate, as a precursor of tungsten, and chromium nitrate, after calcination, not only replenish the chromium in the matrix, but their decomposition products can also activate the surface, making the copper-chromium alloy surface tungsten-rich. This lays the foundation for the subsequent formation of high-strength intermetallic compounds with nickel in tungsten-nickel alloys, thus synergistically improving the hardness, wear resistance, and voltage resistance of copper-chromium alloys.

[0021] Furthermore, the parameters for the vacuum impregnation are: The vacuum impregnation temperature is 30~40℃, the vacuum impregnation time is 3~6h, and the vacuum degree P and the femtosecond laser etching power P are specified. fs The power P of nanosecond laser processing ns The relationship between them is as follows: Where P is in MPa, P fs and P ns The units are all W.

[0022] Explanation: By adjusting the vacuum level of vacuum impregnation using the above formula, the pore structure of the copper-chromium alloy is dynamically matched to ensure that the impregnation solution completely fills the gradient structure on the surface of the copper-chromium alloy, providing a uniform reaction matrix for metallurgical bonding. Furthermore, the coupling of vacuum level and laser energy can optimize the gas discharge of the copper-chromium alloy and the liquid flow of the impregnation solution, avoid interface defects, and enable the elements in the impregnation solution to be evenly distributed, thereby enhancing the alloying effect. At the same time, balancing the laser input energy and impregnation pressure reduces residual stress, thereby improving interface toughness and preventing subsequent alloying cracking at high temperatures.

[0023] Compared with existing methods for melting and infiltrating heterogeneous copper-based alloys, the advantages of this invention are: (1) By introducing a second phase of nickel, this invention can simultaneously solve the problems of melt penetration and bonding strength from the aspects of composition compatibility and interfacial interaction: On the one hand, nickel and copper form an infinitely miscible homocrystalline system (with no upper limit of solubility) and have a high equilibrium solubility in chromium (6~8wt% at 1200℃), which can effectively suppress the segregation and aggregation of chromium at the copper-tungsten-copper-chromium bonding interface and avoid interface defects caused by composition segregation; on the other hand, nickel can act as an interfacial wetting agent to reduce the contact angle between the copper matrix and tungsten particles (from more than 140° for pure copper-tungsten to less than 110° for copper-nickel alloy-tungsten), improve the penetration ability of the molten alloy into the pores of the copper-tungsten 80 skeleton, and fundamentally improve the melt penetration fullness.

[0024] (2) In this invention, the surface treatment of copper-chromium alloy is carried out using femtosecond laser pulses with extremely short durations. The main processes are nonlinear multiphoton absorption and cold working, which etches deep and narrow micropores on the material surface with extremely high precision. This lays the foundation for the substrate structure of subsequent nanosecond laser processing. Then, a hierarchical structure is constructed through nanosecond laser processing. The thermal effect is used to modify and expand the microstructure manufactured by femtosecond laser. On the one hand, the small amount of slag generated by femtosecond laser processing is removed. On the other hand, submicron-level rough textures are generated on the existing micron structure to form a micro / nano composite structure, which greatly increases the specific surface area and constructs multi-level roughness, thereby forming a hierarchical structure, which is conducive to the penetration and spreading of the subsequent impregnation liquid. Then, active chemical components are introduced into the abalone shell-like surface structure through vacuum impregnation. The process involves impregnation in a vacuum environment, which eliminates air from the micropores, prevents bubble residue, and ensures complete solution filling to obtain a dense, defect-free composite coating. Subsequent calcination provides energy to the copper, chromium, and tungsten atoms, enabling them to diffuse into each other at the interface. Furthermore, rapid laser surface melting and solidification treatment can form a dense, fine, hardened grain layer on the copper-based alloy surface, achieving surface nano-sizing and significantly improving its overall performance. HF effectively etches and removes the oxide film on the metal surface, exposing more active metal surfaces and greatly promoting atomic-level contact and diffusion between tungsten, nickel, chromium, and copper. This facilitates the formation of a strong metallurgical bonding interface, enabling a gradient transition from copper-chromium alloy to tungsten-nickel alloy at the interface and improving the bonding strength of the materials. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of the skeleton material obtained in Embodiment 1 of the present invention; Figure 2 This is a diagram of the copper-chromium-copper-tungsten alloy obtained in Example 1 of the present invention. Detailed Implementation

[0026] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0027] Example 1: A method for enhancing the strength of the weld infiltration interface of a copper-tungsten-copper-chromium alloy with second-phase nickel, comprising the following steps: S1, Ingredients The copper-chromium alloy rod and the skeleton material are mixed in a mass ratio of 11.5:36, and the copper-chromium alloy rod is CuCr1 rod. The skeleton material includes tungsten powder and T255 nickel hydroxyl powder in a mass ratio of 100:0.3, wherein the particle size of the tungsten powder is 6~8 μm and the particle size of the T255 nickel hydroxyl powder is 0.1~0.3 μm. S2, ball mill Tungsten powder and nickel powder were first mixed by ball milling. 304 stainless steel was selected as the ball milling material, the ball-to-powder ratio was 3:1, the ball milling speed was 50 Hz, and the ball milling time was 10 hours, yielding the following result: Figure 1 The skeleton material shown; S3. Preparation of tungsten-nickel composite framework The skeleton material obtained in S2 is then pressed into a blank. The billet is placed in a vacuum furnace, and a vacuum is drawn until the furnace pressure is <100 Pa. Then, inert gas is introduced until the filling pressure reaches 1.02 × 10⁻⁶ Pa. 5 At Pa, a stepped sintering process is then performed. The stepped sintering method is as follows: first, the temperature is increased to 600℃ at a rate of 5℃ / min, then the temperature is transferred to vacuum with a vacuum degree of 6×10⁻⁶. -1 Pa, continue to heat to 1325℃ at 3℃ / min and hold for 2h. After holding, cool to room temperature with the furnace. Step sintering is completed to obtain tungsten-nickel composite framework. S4, Melting Infiltration The copper-chromium alloy rod was placed on top of the tungsten-nickel composite frame and then placed together into the vacuum furnace. The vacuum level inside the furnace was 6 × 10⁻⁶. -1 At a pressure of Pa, a stepped melt infiltration process is performed. The stepped melt infiltration method is as follows: first, the temperature is raised to 1350℃ at a rate of 4℃ / min and held for 3.5 hours; then, the temperature is lowered to 700℃ at a rate of 2℃ / min; and then inert gas is introduced until the gas pressure reaches 1.02 × 10⁻⁶. 5 Pa, continue cooling to room temperature, the stepwise melt infiltration is completed, and the result is as follows: Figure 2 The copper-tungsten / copper-chromium alloy shown.

[0028] Example 2: The difference between this example and Example 1 is that the copper-chromium alloy rod and the skeleton material are mixed in a mass ratio of 11:36, and the copper-chromium alloy rod is CuCr1 rod. The skeleton material includes tungsten powder and T255 nickel hydroxyl powder in a mass ratio of 100:0.1.

[0029] Example 3: The difference between this example and Example 1 is that the copper-chromium alloy rod and the skeleton material are mixed in a mass ratio of 12:36, and the copper-chromium alloy rod is CuCr1 rod. The skeleton material includes tungsten powder and T255 nickel hydroxyl powder in a mass ratio of 100:0.5.

[0030] Example 4: The difference between this example and Example 1 is that the particle size of the tungsten powder is 6~7um and the particle size of the T255 nickel hydroxyl powder is 0.1~0.2um.

[0031] Example 5: The difference between this example and Example 1 is that the particle size of the tungsten powder is 7~8 μm and the particle size of the T255 nickel hydroxyl powder is 0.2~0.3 μm.

[0032] Example 6: The difference between this example and Example 1 is that the ball milling speed is 40Hz and the ball milling time is 9.5h.

[0033] Example 7: The difference between this example and Example 1 is that the ball milling speed is 60Hz and the ball milling time is 10.5h.

[0034] Example 8: This example differs from Example 1 in that the stepped sintering method is as follows: first, the temperature is increased to 590℃ at a rate of 4℃ / min, then transferred to vacuum with a vacuum degree of 6×10⁻⁶. -1 Pa, continue to heat to 1300℃ at 2℃ / min and hold for 1.5h. After holding, cool to room temperature with the furnace, and the stepped sintering is completed.

[0035] Example 9: This example differs from Example 1 in that the stepped sintering method is as follows: first, the temperature is increased to 610℃ at a rate of 6℃ / min, then the temperature is transferred to vacuum, with a vacuum degree of 6×10⁻⁶. -1 Pa, continue to heat to 1350℃ at 4℃ / min and hold for 2.5h. After holding, cool to room temperature with the furnace, and the stepped sintering is completed.

[0036] Example 10: This example differs from Example 1 in that the stepped melt infiltration method is as follows: first, the temperature is raised to 1345℃ at a rate of 3℃ / min and held for 3 hours; then, the temperature is lowered to 690℃ at a rate of 1℃ / min, and then inert gas is introduced until the gas pressure reaches 1.02 × 10⁻⁶. 5 Pa.

[0037] Example 11: This example differs from Example 1 in that the stepped melt infiltration method is as follows: first, the temperature is raised to 1355℃ at a rate of 5℃ / min and held for 4 hours; then, the temperature is lowered to 710℃ at a rate of 3℃ / min, and then inert gas is introduced until the gas pressure reaches 1.02 × 10⁻⁶. 5 Pa.

[0038] Example 12: This example differs from Example 1 in that, before performing S4, the bonding surface of the copper-chromium alloy is first subjected to surface treatment. The surface treatment method is as follows: First, femtosecond laser etching is performed on the bonding surface of the copper-chromium alloy, followed by nanosecond laser processing, to obtain a copper-chromium alloy with an abalone shell-like gradient structure on the surface. The femtosecond laser etching has a wavelength of 1064nm, a pulse width of 8ps, a power of 35W, a scanning speed of 0.7m / s, and a scanning spacing of 100μm. The nanosecond laser processing has a wavelength of 265nm, a power of 20W, a frequency of 60kHz, a scanning speed of 1000mm / s, a unit feed rate of 55μm, and a unit feed depth of 40μm. The copper-chromium alloy with the abalone shell-like gradient structure was then vacuum impregnated in an impregnation solution at a solid-liquid ratio of 1g:25ml. The vacuum impregnation temperature was 40℃, the vacuum impregnation time was 6h, and the vacuum degree of the vacuum impregnation was 0.2MPa, thus obtaining the vacuum-impregnated copper-chromium alloy. The method for preparing the impregnation solution is as follows: Secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonyl betaine were added to a 15% (w / w) dilute hydrochloric acid solution and stirred at 28°C and 380 rpm for 40 min to obtain a precursor solution. The mass ratio of secondary alcohol polyoxyethylene ether to cocamidopropyl hydroxysulfonyl betaine is 1:1.5, and the solid-liquid ratio of secondary alcohol polyoxyethylene ether to dilute hydrochloric acid solution is 1g:23ml. Ammonium metatungstate and chromium nitrate were added sequentially to the precursor solution, and the mixture was heated in a water bath at 75°C while being stirred at 600 rpm for 1.5 h to obtain the impregnation solution. The mass ratio of ammonium metatungstate to chromium nitrate is 2.5:1, and the solid-liquid ratio of chromium nitrate to the precursor solution is 1g:28ml. The vacuum-impregnated copper-chromium alloy was washed with deionized water, dried at 80°C for 1 hour, and then calcined under an inert atmosphere (argon). The calcination heating rate was 8°C / min, the temperature was 400°C, and the holding time was 2 hours. After calcination, a mixed gas was introduced and the temperature was lowered to 250°C for activation for 2.5 hours. The mixed gas was hydrogen fluoride and nitrogen in a mass ratio of 1:1.3, resulting in a surface-treated copper-chromium alloy.

[0039] Example 13: The difference between this example and Example 12 is that the wavelength of the femtosecond laser etching is 1064nm, the pulse width is 5psps, the power is 25W, the scanning speed is 0.2m / s, and the scanning spacing is 50μm.

[0040] Example 14: The difference between this example and Example 12 is that the femtosecond laser etching has a wavelength of 1064nm, a pulse width of 12ps, a power of 45W, a scanning speed of 1.2m / s, and a scanning spacing of 150μm.

[0041] Example 15: The difference between this example and Example 12 is that the wavelength of the nanosecond laser processing is 265nm, the power is 10W, the frequency is 50kHz, the scanning speed is 500mm / s, the unit feed rate is 50μm, and the unit feed depth is 20μm.

[0042] Example 16: The difference between this example and Example 12 is that the wavelength of the nanosecond laser processing is 265nm, the power is 30W, the frequency is 70kHz, the scanning speed is 1500mm / s, the unit feed rate is 60μm, and the unit feed depth is 60μm.

[0043] Example 17: The difference between this example and Example 12 is that the copper-chromium alloy with the abalone shell-like gradient structure is vacuum impregnated in the impregnation solution at a solid-liquid ratio of 1g:20ml.

[0044] Example 18: The difference between this example and Example 12 is that the copper-chromium alloy with the abalone shell-like gradient structure is vacuum impregnated in the impregnation solution at a solid-liquid ratio of 1g:30ml.

[0045] Example 19: This example differs from Example 12 in that the calcination heating rate is 5℃ / min, the temperature is 350℃, and the holding time is 1.5h.

[0046] Example 20: This example differs from Example 12 in that the calcination heating rate is 10℃ / min, the temperature is 450℃, and the holding time is 2.5h.

[0047] Example 21: The difference between this example and Example 12 is that after calcination, a mixed gas is introduced and the temperature is lowered to 200°C for 2 hours for activation. The mixed gas is hydrogen fluoride and nitrogen in a mass ratio of 1:1.

[0048] Example 22: The difference between this example and Example 12 is that after calcination, a mixed gas is introduced and the temperature is lowered to 300°C for 3 hours for activation. The mixed gas is hydrogen fluoride and nitrogen in a mass ratio of 1:1.5.

[0049] Example 23: The difference between this example and Example 12 is that secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonyl betaine were added to a 10% dilute hydrochloric acid solution and stirred at 25°C and 350 rpm for 35 min to obtain a precursor solution.

[0050] Example 24: The difference between this example and Example 12 is that secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonyl betaine were added to a 20% (w / w) dilute hydrochloric acid solution and stirred at 30°C and 400 rpm for 45 min to obtain a precursor solution.

[0051] Example 25: The difference between this example and Example 12 is that ammonium metatungstate and chromium nitrate were added to the precursor solution in sequence, heated in a water bath at 65°C, and stirred at 550 rpm for 1 hour to obtain the impregnation solution.

[0052] Example 26: The difference between this example and Example 12 is that ammonium metatungstate and chromium nitrate were added sequentially to the precursor solution, heated in a water bath at 85°C, and stirred at 650 rpm for 2 hours to obtain the impregnation solution.

[0053] Example 27: This example differs from Example 12 in that the mass ratio of ammonium metatungstate to chromium nitrate is 2:1, and the solid-liquid ratio of chromium nitrate to the precursor solution is 1g:25ml.

[0054] Example 28: This example differs from Example 12 in that the mass ratio of ammonium metatungstate to chromium nitrate is 3:1, and the solid-liquid ratio of chromium nitrate to the precursor solution is 1g:30ml.

[0055] Example 29: This example differs from Example 1 in that the parameters for vacuum impregnation are: The vacuum impregnation temperature is 35°C, the vacuum impregnation time is 4.5 hours, and the vacuum degree P and the femtosecond laser etching power P are specified. fs The power P of nanosecond laser processing ns The relationships are shown below (it can be understood that the following formulas represent equations, that is, the value of vacuum degree P is the value calculated on the right side of the equation): Where P is in MPa, P fs and P ns The units are all W.

[0056] Example 30: This example differs from Example 29 in that the vacuum impregnation temperature is 30°C and the vacuum impregnation time is 3 hours.

[0057] Example 31: This example differs from Example 29 in that the vacuum impregnation temperature is 40°C and the vacuum impregnation time is 6 hours.

[0058] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and aims to illustrate the practical application effect of the present invention.

[0059] Investigation 1: Investigate the effect of nickel content on the bonding strength of copper-chromium-copper-tungsten alloys.

[0060] Table 1. Bond strength of copper-chromium-copper-tungsten alloys in Examples 1-3 and Comparative Examples 1-3

[0061] The difference between Comparative Example 1 and Example 1 is that nickel powder was not added, but melting and infiltration were carried out in a vacuum environment; The difference between Comparative Example 2 and Example 1 is that nickel powder was added, but the melting and infiltration was carried out in a non-vacuum environment; The difference between Comparative Example 3 and Example 1 is that no nickel powder was added, and the melting and infiltration were carried out in a non-vacuum environment; As shown in Table 1, Comparative Example 1 lacks the second phase nickel, resulting in a significant decrease in the solubility of copper, chromium, and tungsten, leading to a decrease in melting and infiltration permeability and a significant decrease in the bonding strength of the resulting copper-chromium-copper-tungsten alloy. Comparative Example 2, although containing nickel powder, lacks the vacuum environment required for melting and infiltration. Mechanical peeling tests on the bonding surfaces of the melt-infiltrated samples revealed the presence of a significant chromium oxide phase. This chromium oxide phase is a brittle compound that cannot effectively bond with the copper-tungsten skeleton or the copper-chromium alloy and also blocks the metallurgical bonding path at the interface, resulting in a significant decrease in interfacial bonding strength and ultimately causing quality problems such as low tensile strength and easy delamination at the bonding surface. Comparative Example 3 lacks both nickel powder and a vacuum environment, thus combining the disadvantages of Comparative Examples 1 and 2. Therefore, the parameter effects of Comparative Examples 1 to 3 are significantly reduced compared to Examples 1 to 3, demonstrating that the introduction of the second phase nickel and vacuum melting and infiltration in this application effectively enhances the bonding strength of the copper-chromium-copper-tungsten alloy. Furthermore, comparing Examples 1 to 3, it can be seen that as the nickel content increases, the bonding strength continuously improves. However, if the nickel content increases to 0.5 wt% of the tungsten powder, the electrical conductivity of the copper-chromium-copper-tungsten alloy will drop sharply to 17 MS / m, resulting in a decline in overall performance. Therefore, from a comprehensive perspective, the copper-chromium-copper-tungsten alloy with the nickel content in Example 1 has relatively better overall performance.

[0062] Investigation 2: Investigate the effect of the preparation process on the bonding strength of the copper-chromium-copper-tungsten alloy.

[0063] Table 2. Bond strength of copper-chromium-copper-tungsten alloys in Examples 4 to 11

[0064] As shown in Table 2, excessively small or large raw material particle size, excessively small or large ball milling parameters, excessively small stepped sintering parameters, and excessively small stepped melting infiltration parameters will all reduce the bonding strength of the copper-chromium-copper-tungsten alloy. In Examples 9 and 11, the stepped sintering and stepped melting infiltration parameters are larger, thus improving the bonding strength of the copper-chromium-copper-tungsten alloy compared to Example 1. However, the improvement in Examples 9 and 11 is less than the increase in temperature and time. Therefore, from an economic point of view, the parameter effect of Example 1 is relatively better.

[0065] Investigation 3: Investigate the effect of the preparation process on the bonding strength of the copper-chromium-copper-tungsten alloy.

[0066] Table 3. Bond strength of copper-chromium-copper-tungsten alloys in Examples 12-22 and Comparative Examples 4-5

[0067] The difference between Comparative Example 4 and Example 12 is that only femtosecond laser etching is performed; The difference between Comparative Example 5 and Example 12 is that no activation treatment was performed after calcination; As shown in Table 3, the surface treatment of copper-chromium alloy followed by vacuum melting promotes atomic-level contact and diffusion between tungsten, nickel, chromium and copper, making it easier to form a strong metallurgical bonding interface, thereby significantly improving the bonding strength of copper-chromium-copper-tungsten alloy. Comparing Examples 12-22 with Comparative Examples 4-5, it can be seen that without nanosecond laser processing, an abalone shell-like structure cannot be formed, resulting in a decrease in specific surface area. Compared to the abalone shell-like structure, the impregnation range of the impregnation solution is weakened, thus weakening the diffusion effect of each element. Comparative Example 5 lacks activation treatment, resulting in a decrease in coating density, which affects surface activity during bonding. Therefore, the improvement in the bonding strength of the copper-chromium-copper-tungsten alloy by Comparative Examples 4-5 is lower than that of Examples 12-22. Comparing Examples 12 to 22, it can be seen that excessively small or large femtosecond laser etching parameters, excessively small or large nanosecond laser processing parameters, excessively small or large impregnation parameters, excessively small calcination parameters, and excessively small or large activation parameters will all reduce the improvement in the bonding strength of the copper-chromium-copper-tungsten alloy. In Example 20, the calcination temperature is higher and the time is longer, thus the bonding strength of the copper-chromium-copper-tungsten alloy is improved compared to Example 12. However, the improvement in Example 20 is less than the increase in parameters. Therefore, from an economic point of view, the parameter effect of Example 12 is relatively better.

[0068] Investigation 4: Investigate the effect of impregnation solution on the bonding strength of copper-chromium-copper-tungsten alloy.

[0069] Table 4. Bond strength of copper-chromium-copper-tungsten alloys in Examples 23-28

[0070] As shown in Table 4, too small or too large a proportion of secondary alcohol polyoxyethylene ether, too small or too large a preparation parameter of the impregnation solution, and too small or too large a proportion of ammonium metatungstate will reduce the improvement in the bonding strength of the copper-chromium-copper-tungsten alloy. Therefore, from a comprehensive perspective, the parameter effect of Example 12 is relatively better.

[0071] Investigation 5: Investigate the effect of impregnation solution on the bonding strength of copper-chromium-copper-tungsten alloy.

[0072] Table 5. Bond strength of copper-chromium-copper-tungsten alloys in Examples 29-31

[0073] As shown in Table 5, linking the vacuum degree of vacuum impregnation with the laser power dynamically matches the pore structure of the copper-chromium alloy, ensuring that the impregnation liquid completely fills the gradient structure on the surface of the copper-chromium alloy, providing a uniform reaction matrix for metallurgical bonding. Furthermore, the coupling of vacuum degree and laser energy can optimize the gas discharge of the copper-chromium alloy and the liquid flow of the impregnation liquid, avoid interface defects, and enable the elements in the impregnation liquid to be evenly distributed, thereby enhancing the alloying effect. At the same time, balancing the laser input energy and impregnation pressure reduces residual stress, thereby improving the interface toughness and preventing subsequent alloying from cracking at high temperatures. Therefore, compared with Example 12, the improvement in the bonding strength of the copper-chromium-copper-tungsten alloy is further increased. Comparing Examples 29 to 31, it can be seen that if the parameters of vacuum impregnation are too small or too large, the improvement in the bonding strength of the copper-chromium-copper-tungsten alloy will be reduced. Therefore, from a comprehensive point of view, the parameters of Example 29 are relatively better.

Claims

1. A method for enhancing the strength of the weld infiltration interface of copper-tungsten-copper-chromium alloys with a second-phase nickel, characterized in that, Includes the following steps: S1, Ingredients The copper-chromium alloy bars and the skeleton material are mixed in a mass ratio of 11~12:36; The skeleton material includes tungsten powder and nickel powder in a mass ratio of 100:0.1~0.5, wherein the particle size of the tungsten powder is 6~8 μm and the particle size of the nickel powder is 0.1~0.3 μm; S2, ball mill Tungsten powder and nickel powder are first ball-milled and mixed to obtain the framework material; S3. Preparation of tungsten-nickel composite framework The skeleton material obtained in S2 is then pressed into a blank. The billet is placed in a vacuum furnace, and a vacuum is drawn until the furnace pressure is <100 Pa. Then, inert gas is introduced until the filling pressure reaches 1.02 × 10⁻⁶ Pa. 5 At Pa, a step-by-step sintering process is then performed to obtain a tungsten-nickel composite framework; S4, Melting Infiltration The copper-chromium alloy rod is placed on top of the tungsten-nickel composite skeleton and then placed together into the vacuum furnace. The vacuum degree inside the furnace is ≤6×10⁻⁶. -1 At Pa, a stepped melting process is carried out to obtain a copper-tungsten-copper-chromium alloy.

2. The method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, The nickel powder is T255 hydroxy nickel powder.

3. The method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, The copper-chromium alloy bar is a CuCr1 bar.

4. The method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, In S2, 304 stainless steel is selected as the ball milling material, the ball-to-material ratio is 3:1, the ball milling speed is 40~60Hz, and the ball milling time is 9.5~10.5h.

5. The method for enhancing the bonding strength of a copper-tungsten-copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, In S3, the stepped sintering method is as follows: first, the temperature is raised to 590~610℃ at a rate of 4~6℃ / min, then the temperature is transferred to vacuum, with a vacuum degree ≤6×10. -1 Pa, continue to heat to 1300~1350℃ at 2~4℃ / min, and hold for 1.5~2.5h. After holding, cool to room temperature with the furnace, and the stepped sintering is completed.

6. The method for enhancing the bonding strength of a copper-tungsten-copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, In S4, the stepped melting and infiltration method is as follows: first, the temperature is raised to 1345-1355℃ at a rate of 3-5℃ / min, held for 3-4 hours, then the temperature is lowered to 690-710℃ at a rate of 1-3℃ / min, and then inert gas is introduced until the gas pressure reaches 1.02×10⁻⁶. 5 Pa, continue cooling to room temperature, and the step-by-step melting infiltration is completed.

7. The method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, Before proceeding to step S4, the bonding surfaces of the copper-chromium alloy are first subjected to surface treatment. The surface treatment method is as follows: First, femtosecond laser etching is performed on the bonding surface of the copper-chromium alloy, followed by nanosecond laser processing, to obtain a copper-chromium alloy with an abalone shell-like gradient structure on the surface. The femtosecond laser etching has a wavelength of 1064nm, a pulse width of 5ps~12ps, a power of 25~45W, a scanning speed of 0.2~1.2m / s, and a scanning spacing of 50~150μm. The nanosecond laser processing has a wavelength of 265nm, a power of 10~30W, a frequency of 50~70kHz, a scanning speed of 500~1500mm / s, a unit feed rate of 50~60μm, and a unit feed depth of 20~60μm. The copper-chromium alloy with the abalone shell-like gradient structure is then vacuum impregnated in an impregnation solution at a solid-liquid ratio of 1g:20~30ml to obtain the vacuum-impregnated copper-chromium alloy. After being vacuum impregnated, the copper-chromium alloy is washed, dried, and then calcined in an inert atmosphere. The calcination heating rate is 5~10℃ / min, the temperature is 350~450℃, and the holding time is 1.5~2.5h. After calcination, a mixed gas is introduced and the temperature is lowered to 200~300℃ for activation for 2~3h. The mixed gas is hydrogen fluoride and nitrogen in a mass ratio of 1:1~1.5, to obtain a surface-treated copper-chromium alloy.

8. The method for enhancing the bonding strength of a copper-tungsten / copper-chromium alloy with second-phase nickel as described in claim 1, characterized in that, The method for preparing the impregnation solution is as follows: Secondary alcohol polyoxyethylene ether and cocamidopropyl hydroxysulfonyl betaine were added to a 10-20% (w / w) dilute hydrochloric acid solution and stirred at 25-30°C and 350-400 rpm for 35-45 min to obtain a precursor solution. The mass ratio of secondary alcohol polyoxyethylene ether to cocamidopropyl hydroxysulfonyl betaine is 1:1~2, and the solid-liquid ratio of secondary alcohol polyoxyethylene ether to dilute hydrochloric acid solution is 1g:20~25ml. Ammonium metatungstate and chromium nitrate were added sequentially to the precursor solution, and the solution was heated in a water bath at 65-85°C while being stirred at 550-650 rpm for 1-2 hours to obtain the impregnation solution. The mass ratio of ammonium metatungstate to chromium nitrate is 2-3:1, and the solid-liquid ratio of chromium nitrate to the precursor solution is 1g:25-30ml.

9. The method for enhancing the bonding strength of a copper-tungsten-copper-chromium alloy with second-phase nickel as described in claim 7, characterized in that, The parameters for the vacuum impregnation are: The vacuum impregnation temperature is 30~40℃, the vacuum impregnation time is 3~6h, and the vacuum degree P and the femtosecond laser etching power P are specified. fs The power P of nanosecond laser processing ns The relationship between them is as follows: Where P is in MPa, P fs and P ns The units are all W.

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