High-strength, high-conductivity and high-plasticity CuCoNiSi alloy as well as preparation method and application thereof

Abstract

The invention belongs to the field of copper alloys, and discloses a high-strength, high-conductivity and high-plasticity CuCoNiSi series alloy of which the conductivity is not lower than 50% IACS, the tensile strength is not lower than 700 MPa, and the product of strength and ductility is not lower than 9.00 GPa.%. The invention also discloses a preparation method and application of the alloy, and the preparation method comprises the following steps: firstly preparing a CuCoNiSi alloy ingot, and then sequentially carrying out homogenization treatment, hot rolling treatment, solution treatment, first cold rolling treatment, first aging treatment, second cold rolling treatment, second aging treatment, third cold rolling treatment and third aging treatment. And the CuCoNiSi series alloy is obtained. Through cooperative control of microalloying component design and a multi-stage deformation-graded aging process, a stable multi-scale precipitation structure is constructed in the Cu-Ni-Co-Si alloy, so that a nano-scale precipitation phase, a micron-scale precipitation phase and a deformation substructure have a synergistic effect, the strength and the electric conductivity are improved, and meanwhile, the mechanical property of the Cu-Ni-Co-Si alloy is improved. And the problems of strain localization and early-stage fracture are effectively relieved, so that synergism and unification of high strength, high conductivity and high plasticity are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of copper alloys, and particularly relates to a CuCoNiSi system alloy with high strength, high electrical conductivity and high plasticity, and a preparation method and application thereof. BACKGROUND

[0002] High-strength and high-conductivity copper alloy plate and strip material is a key basic material in connectors, lead frames and new energy automobile electronic components. With the development of electronic devices towards high density, miniaturization and high reliability, the material not only needs to have relatively high tensile strength and electrical conductivity, but also needs to have good plasticity and forming stability at the same time to meet the comprehensive requirements of complex stamping, bending and service reliability. Therefore, the synergistic consideration of high strength, high electrical conductivity and high plasticity has become a common requirement for high-end copper alloy materials.

[0003] In existing engineering applications, Cu-Cr and Cu-Cr-Zr alloy systems have relatively high electrical conductivity, which can generally reach more than 75% IACS, but their precipitation strengthening ability is limited, and the tensile strength is difficult to exceed 500 MPa, and the plasticity has little room for improvement in the high-strength state. On the other hand, Cu-Ni-Si system alloys can precipitate Ni2Si strengthening phase during aging, and the tensile strength can reach more than 800 MPa, but due to the solid solution scattering effect of Ni and Si in the matrix, the electrical conductivity is generally difficult to stabilize at more than 50% IACS, and the plasticity of the material decreases significantly in the high-strength state, and the strength-plasticity product is low.

[0004] To solve the above problems, some researches propose to introduce Co element into Cu-Ni-Si alloy to regulate the precipitation behavior, so that the alloy can serve at a higher strength and electrical conductivity level. However, existing public technologies mostly take strength and electrical conductivity as the main performance indicators, and pay insufficient attention to plasticity and the synergistic relationship between strength, conductivity and plasticity. Under the conditions of high strength and relatively high electrical conductivity, the material often still has the problems of insufficient plasticity, low strength-plasticity product or poor microstructure stability, which is difficult to meet the comprehensive needs of complex stamping forming and long-term service.

[0005] Therefore, developing a micro-alloying and industrialized multi-stage deformation heat treatment process, while maintaining the tensile strength of not less than 700 MPa and the electrical conductivity of not less than 50% IACS, significantly improving the plasticity level, realizing the synergistic optimization of high strength, high electrical conductivity and high plasticity, is still a key technical problem to be solved in the field. SUMMARY

[0006] The present application aims to overcome the deficiencies and shortcomings mentioned in the background art, and provides a CuCoNiSi system alloy with high strength, high electrical conductivity and high plasticity, and a preparation method and application thereof.

[0007] To solve the above technical problems, the core of the present application is that: by the synergistic control of micro-alloying component design and multi-stage deformation-graded aging process, a stable multi-scale precipitation structure is constructed in the Cu-Ni-Co-Si alloy, so that the nanoscale precipitates, micron-scale precipitates and deformation substructure synergistically act, while improving the strength and conductivity, effectively relieving the strain localization and early fracture problem, so as to realize the synergistic unity of high strength, high conductivity and high plasticity.

[0008] The technical scheme provided by the present application is: A high-strength high-conductivity high-plasticity CuCoNiSi alloy, by weight percentage, the alloy comprises the following component composition: Ni 1.0-3.5%, Co 1.0-2.5%, Si 0.5-1.5%, Cr 0.01-0.3%, Fe 0.01-0.3%, Zr 0.01-0.3%, Mg 0.01-0.3%, Ag 0.01-0.3%, V 0.01-0.3%, the balance is copper and inevitable impurities.

[0009] The high-strength high-conductivity high-plasticity CuCoNiSi alloy, preferably, the total weight percentage of Cr, Fe, Zr, Mg, Ag and V elements is 0.1-0.5%.

[0010] The high-strength high-conductivity high-plasticity CuCoNiSi alloy, preferably, the (Ni + Co) / Si mass ratio is controlled at 3.0-7.0.

[0011] The high-strength high-conductivity high-plasticity CuCoNiSi alloy, preferably, the conductivity of the high-strength high-conductivity high-plasticity CuCoNiSi alloy is not less than 50 %IACS, the tensile strength is not less than 700 MPa, and the strength plastic product is not less than 9.00 GPa·%.

[0012] Ni, Co and Si are the main strengthening elements in the alloy, and can form nanoscale and micron-scale (Ni, Co) 2Si multi-scale precipitates during aging. Through the synergistic control of Co element, the precipitates tend to be small and uniform, thereby enhancing the precipitation strengthening effect; at the same time, the formation of precipitates reduces the solid solution atom content in the matrix, reduces electron scattering, and is beneficial to the improvement of conductivity. Cr, Fe, Zr and other micro-alloying elements have limited solid solubility in the Cu matrix, and are prone to segregation during hot working and aging, and exist in the form of fine dispersed enrichment phase or second phase, which pins the grain boundaries and dislocations, inhibits recrystallization and grain growth, and stabilizes the main strengthening precipitates, thereby improving the organizational stability and high temperature softening resistance of the alloy.

[0013] The addition of Co can increase the nucleation rate of the precipitated phase and inhibit coarsening, making the precipitated phase finer and more uniform, thereby enhancing precipitation strengthening. Simultaneously, the formation of this precipitated phase reduces the solid solubility in the matrix, decreases electron scattering, and improves the material's electrical conductivity. Trace amounts of elements such as Cr, Fe, and Zr, due to their limited solid solubility in Cu, tend to agglomerate and form fine, dispersed second phases or enriched phases during hot working and aging. On one hand, these enriched or second phases can directly pin dislocations and grain boundaries, producing a certain synergistic strengthening effect on the alloy's strength; on the other hand, their stabilizing effect on grain boundaries and precipitated phase interfaces can regulate the nucleation and growth behavior of the main strengthening phase, inhibit coarsening, and maintain the stability of the nano-precipitated structure, thus achieving a synergistic improvement in both strengthening effect and microstructure stability.

[0014] In this invention, the Ni content is controlled between 1.0% and 3.5%. When the Ni content exceeds 3.5%, the amount of solid solution in the matrix increases, electron scattering is enhanced, and conductivity decreases. When the Ni content is below 1.0%, the amount of precipitated phase is insufficient, making it difficult to ensure that the tensile strength of the alloy reaches 700 MPa. To obtain a good balance between strengthening and conductivity, the (Ni + Co) / Si ratio needs to be reasonably controlled. When (Ni + Co) / Si is below 3.0, Si is relatively excessive and easily partially dissolves in the copper matrix, significantly enhancing electron scattering and leading to a significant decrease in conductivity. When (Ni + Co) / Si is above 7.0, excessive Ni and Co dissolve, which is also detrimental to maintaining conductivity and has limited effect on further improving the strength of the alloy. Therefore, in this invention, the mass ratio of (Ni + Co) / Si is preferably controlled between 3.0 and 7.0. The total amount of trace elements such as Cr, Fe, and Zr is controlled between 0.1% and 0.5%. If the total amount exceeds 0.5%, it is easy to form coarse second phase or intermetallic phase during solidification and hot working, which has limited strengthening effect and may become crack source, leading to a decrease in plasticity, fatigue performance and cold working performance.

[0015] As a general inventive concept, the present invention also provides a method for preparing the above-mentioned high-strength, high-conductivity, and high-ductility CuCoNiSi alloy, comprising the following steps: (1) Prepare materials according to the weight percentage of the element composition, put copper, nickel, cobalt, iron and silver raw materials into the heating furnace to melt, add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon raw materials, and finally add zirconium raw materials and magnesium raw materials. After they are completely melted, keep them warm and stir, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot. (2) The CuCoNiSi alloy ingot is subjected to homogenization treatment, hot rolling treatment, solution treatment, first cold rolling treatment, first aging treatment, second cold rolling treatment, second aging treatment, third cold rolling treatment, and third aging treatment in sequence to obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy.

[0016] In the above preparation method, preferably, in step (1), the melting temperature is controlled at 1300-1500 ℃, the holding temperature is controlled at 1100-1300 ℃, and the holding time is controlled at 10-30 min. This temperature range is intended to ensure that all raw materials, especially high-melting-point alloying elements, can be fully melted, and to promote the yield of subsequently added active elements (such as Mg and Zr) and reduce component segregation.

[0017] In the above-mentioned preparation method, preferably, in step (2), the homogenization treatment temperature is 900-980 ℃ and the holding time is 4-8 h. The purpose of the homogenization treatment is to eliminate dendritic segregation inside the ingot and make the composition distribution uniform. If the temperature or time is insufficient, segregation is difficult to eliminate; if the temperature is too high or the time is too long, it will lead to excessive grain growth and increase energy consumption.

[0018] In the above preparation method, preferably, in step (2), the deformation of the hot rolling treatment is 50-80%, the hot rolling final rolling temperature is 850-900 ℃, and the plate is immediately water-cooled after the hot rolling treatment; the purpose of this process is to transform the as-cast structure into the processed structure, and to break the coarse second phase formed during the casting process to obtain a supersaturated solid solution, in order to prepare for subsequent aging precipitation, while avoiding the precipitation of coarse phases during the cooling process.

[0019] The solution treatment temperature is 900-980 ℃, and the holding time is 4-8 h. After the solution treatment, the plate is water-cooled. The purpose of the solution treatment is to fully dissolve the second phase that may precipitate after hot rolling and that is inherent in the ingot into the copper matrix to obtain a single supersaturated solid solution. Too low a temperature or too short a time will lead to insufficient dissolution; too high a temperature will easily cause grain coarsening and element burn-off. When the temperature is higher than 980 ℃, it will cause significant grain growth and increase element volatilization and oxidation; when the temperature is lower than 900 ℃, it will cause insufficient Ni, Co, and Si solid solution, affecting the quantity and size control of precipitates during subsequent aging, which is not conducive to obtaining the expected strengthening effect.

[0020] In the above preparation method, preferably, in step (2), the deformation amount of the first cold rolling treatment is 50-80%; the purpose is to introduce high-density dislocations into the soft structure after solid solution treatment, so as to provide a large number of sites for the nucleation of precipitates such as (Ni, Co)2Si in the first aging treatment.

[0021] The temperature of the first aging treatment is 450-500 ℃, and the aging holding time is 2-10 h. After the aging treatment, the plate is water-cooled. This mainly promotes the large-scale and dispersed precipitation of the (Ni, Co)2Si phase, which increases the conductivity of the plate to about 50% IACS, while significantly improving the strength.

[0022] The deformation amount of the second cold rolling process is 50%-80%; it further refines the grains and precipitated phases, and introduces new dislocations.

[0023] The second aging treatment is performed at a temperature of 350-400 ℃ and the aging holding time is 1-5 h. After the aging treatment, the plate is water-cooled. The purpose of this aging is to allow finer second phases to precipitate at the defects introduced by the second cold rolling and to adjust the morphology of the existing precipitates so that the alloy reaches its peak strength state.

[0024] The deformation amount of the third cold rolling process is 50-80%; this cold rolling is carried out at the peak strength state after the second aging, aiming to further strengthen the alloy through appropriate deformation.

[0025] The third aging treatment is performed at a temperature of 300-350 ℃, with an aging holding time of 0.5-2 h. After the aging treatment, the plate is water-cooled. The main purpose is to stabilize the microstructure and properties of the material, eliminate internal stress, and ensure that the conductivity remains stable at a high level.

[0026] This invention employs a synergistic process of casting-homogenization-hot rolling-solution treatment-multi-stage deformation heat treatment (cold rolling + aging) to prepare CuCoNiSi alloy plates with high strength, high conductivity, and high plasticity. Homogenization treatment eliminates ingot compositional segregation, and hot rolling breaks up the coarse as-cast structure. Solution treatment obtains a single supersaturated solid solution, laying the foundation for subsequent precipitation strengthening. Multi-stage cold rolling continuously introduces high-density dislocations and deformation structures, providing numerous nucleation sites for precipitates. During staged aging, nanoscale and microscale (Ni, Co)₂Si multi-scale precipitates are formed in the plate: a large number of fine and dispersed nanoscale phases significantly improve strength and purify the matrix to enhance conductivity through interaction with dislocations and deformation substructures; microscale phases enhance microstructural stability and prevent local stress concentration by interacting with grain boundaries and dislocations, thereby improving the plasticity of the material. Through precise and coordinated control of this multi-stage deformation heat treatment process, the synergistic effect of multi-scale precipitated phases, dislocations, and deformation substructures achieves high strength, high conductivity, and excellent plasticity in the sheet material.

[0027] As a general inventive concept, the present invention also provides the application of the above-mentioned high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy, or the high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy prepared by the above-mentioned preparation method, in connectors, lead frames, relay contacts, electrical contacts, elastic conductive elements, and conductive connection structures.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention is based on the CuCoNiSi alloy system and constructs a stable multi-scale precipitation structure by introducing microalloying elements such as Cr, Fe, and Zr, combined with the "solid solution-multi-stage deformation heat treatment" process. During the aging process, the alloy can form high-density nanoscale coherent precipitates and dispersed micron-scale precipitates, which effectively improves the alloy strength and reduces the content of solid solution atoms in the matrix, thereby improving the conductivity. Elements such as Cr, Fe, and Zr regulate the evolution behavior of precipitates and inhibit coarsening by pinning and stabilizing grain boundaries and precipitate interfaces, further enhancing the precipitation strengthening effect and microstructure stability. The synergistic effect of the formed nanoscale precipitates, dispersed precipitates, and deformation-introduced substructures not only effectively hinders dislocation movement and improves alloy strength, but also facilitates the stepwise transmission of dislocations and strain coordination, avoiding local strain concentration, thereby achieving high strength and high conductivity while maintaining high plasticity and excellent microstructure thermal stability.

[0029] (2) The present invention adopts the preparation process route of “melting and casting – homogenization – hot rolling – solution treatment – ​​multi-stage deformation heat treatment (cold rolling + aging)”. The process window is wide, it is well matched with existing copper alloy plate and strip production equipment, the process is highly continuous, it is easy to realize industrial production, and it has good process feasibility.

[0030] (3) The high-strength, high-conductivity and high-plasticity CuCoNiSi alloy obtained by the present invention has a conductivity of not less than 50% IACS, a tensile strength of not less than 700 MPa, and a strength-plasticity product of not less than 9.00 GPa·%, achieving a synergistic balance of high strength, high conductivity and high plasticity, which can meet the high requirements of high-end connectors, lead frames and other components for material performance. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a scanning electron microscope (SEM) image of the tensile fracture surface of the high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate prepared in Example 4 of the present invention.

[0033] Figure 2 This is a transmission electron microscope (TEM) bright-field image of the high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate prepared in Example 4 of the present invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] Example 1: A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy of the present invention comprises the following components by weight percentage: Ni 1.0%, Co 2.5%, Si 0.5%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, wherein the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, and the balance is copper and unavoidable impurities.

[0038] The preparation method of the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy in this embodiment includes the following steps: (1) Prepare the raw materials according to the weight percentage of the element composition. Put the electrolytic copper block, nickel granules, cobalt granules, iron granules and silver granules into the heating furnace, heat to 1300 ℃ to melt the raw materials, then add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon granules, and finally add zirconium granules and magnesium granules. After they are completely melted, keep them at 1100 ℃ for 10 min, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot; (2) The ingot obtained after step (1) is homogenized, wherein the homogenization temperature is 900 ℃ and the holding time is 8 h. After homogenization, hot rolling is performed immediately, the deformation of hot rolling is 80%, the final rolling temperature is 850~900 ℃, and the plate is immediately water-cooled after hot rolling.

[0039] (3) The hot-rolled sheet obtained after step (2) is subjected to solution treatment at a temperature of 950 ℃ and a holding time of 4 h. After solution treatment, the sheet is cooled by water.

[0040] (4) The sheet obtained after step (3) is subjected to a first cold rolling process with a deformation of 80%.

[0041] (5) The board obtained after step (4) is subjected to the first aging treatment. The temperature of the first aging treatment is 450℃ and the heat preservation time is 2 h. After the aging treatment, the board is water-cooled.

[0042] (6) The aged sheet obtained after step (5) is subjected to a second cold rolling process with a deformation of 50%.

[0043] (7) The board obtained after step (6) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the heat preservation time is 5 h. After the aging treatment, the board is water-cooled.

[0044] (8) The aged sheet obtained after step (7) is subjected to a third cold rolling process with a deformation of 60%.

[0045] (9) The plate obtained after step (8) is subjected to a third aging treatment. The temperature of the third aging treatment is 350℃ and the holding time is 2 h. After the aging treatment, the plate is water-cooled to finally obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate.

[0046] Example 2: A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy of the present invention comprises the following components by weight percentage: Ni 2.0%, Co 1.5%, Si 0.8%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, wherein the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, and the balance is copper and unavoidable impurities.

[0047] The preparation method of the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy in this embodiment includes the following steps: (1) Prepare the raw materials according to the weight percentage of the element composition. Put the electrolytic copper block, nickel granules, cobalt granules, iron granules and silver granules into the heating furnace, heat to 1350 ℃ to melt the raw materials, then add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon granules, and finally add zirconium granules and magnesium granules. After they are completely melted, keep them at 1150 ℃ for 15 min, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot; (2) The ingot obtained after step (1) is homogenized, wherein the homogenization temperature is 950 ℃ and the holding time is 4 h. After homogenization, hot rolling is performed immediately, the deformation of hot rolling is 50%, the final rolling temperature is 850~900 ℃, and the plate is immediately water-cooled after hot rolling.

[0048] (3) The hot-rolled sheet obtained after step (2) is subjected to solution treatment at a temperature of 900 ℃ and a holding time of 8 h. After solution treatment, the sheet is water-cooled.

[0049] (4) The sheet obtained after step (3) is subjected to a first cold rolling process with a deformation of 60%.

[0050] (5) The board obtained after step (4) is subjected to the first aging treatment. The temperature of the first aging treatment is 450℃ and the heat preservation time is 4 h. After the aging treatment, the board is water-cooled.

[0051] (6) The aged sheet obtained after step (5) is subjected to a second cold rolling process with a deformation of 60%.

[0052] (7) The board obtained after step (6) is subjected to a second aging treatment. The temperature of the second aging treatment is 350℃ and the holding time is 2 h. After the aging treatment, the board is water-cooled.

[0053] (8) The aged sheet obtained after step (7) is subjected to a third cold rolling process with a deformation of 80%.

[0054] (9) The plate obtained after step (8) is subjected to a third aging treatment. The temperature of the third aging treatment is 300℃ and the holding time is 1h. After the aging treatment, the plate is water-cooled to finally obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate.

[0055] Example 3: A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy of the present invention comprises the following components by weight percentage: Ni 3.0%, Co 1.0%, Si 1.2%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, wherein the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, and the balance is copper and unavoidable impurities.

[0056] The preparation method of the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy in this embodiment includes the following steps: (1) Prepare the raw materials according to the weight percentage of the element composition. Put the electrolytic copper block, nickel granules, cobalt granules, iron granules and silver granules into the heating furnace and heat it to 1400 ℃ to melt the raw materials. Then add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, followed by silicon block, and finally zirconium granules and magnesium granules. After they are completely melted, keep them at 1200 ℃ for 20 min. Then pour the melt into the mold and cool it to obtain CuCoNiSi alloy ingot.

[0057] (2) The ingot obtained after step (1) is homogenized at a temperature of 950 ℃ and a holding time of 6 h. After homogenization, hot rolling is performed immediately. The deformation of hot rolling is 60%, and the final rolling temperature is 850~900 ℃. After hot rolling, the plate is immediately water-cooled.

[0058] (3) The hot-rolled sheet obtained after step (2) is subjected to solution treatment at a temperature of 980 ℃ and a holding time of 6 h. After solution treatment, the sheet is water-cooled.

[0059] (4) The sheet obtained after step (3) is subjected to a first cold rolling process with a deformation of 50%.

[0060] (5) The board obtained after step (4) is subjected to the first aging treatment. The temperature of the first aging treatment is 500℃ and the heat preservation time is 6 h. After the aging treatment, the board is water-cooled.

[0061] (6) The aged sheet obtained after step (5) is subjected to a second cold rolling process with a deformation of 80%.

[0062] (7) The board obtained after step (6) is subjected to a second aging treatment. The temperature of the second aging treatment is 350℃ and the heat preservation time is 3 h. After the aging treatment, the board is water-cooled.

[0063] (8) The aged sheet obtained after step (7) is subjected to a third cold rolling process with a deformation of 60%.

[0064] (9) The plate obtained after step (8) is subjected to a third aging treatment. The temperature of the third aging treatment is 300℃ and the holding time is 2 h. After the aging treatment, the plate is water-cooled to finally obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate.

[0065] Example 4: A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy of the present invention comprises the following components by weight percentage: Ni 2.5%, Co 1.2%, Si 1.0%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, wherein the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, and the balance is copper and unavoidable impurities.

[0066] The preparation method of the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy in this embodiment includes the following steps: (1) Prepare the raw materials according to the weight percentage of the element composition. Put the electrolytic copper block, nickel granules, cobalt granules, iron granules and silver granules into the heating furnace, heat to 1450 ℃ to melt the raw materials, then add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon granules, and finally add zirconium granules and magnesium granules. After they are completely melted, keep them at 1250 ℃ for 25 min, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot; (2) The ingot obtained after step (1) is homogenized at a temperature of 900 ℃ and held for 4 h. After homogenization, hot rolling is performed immediately. The deformation of hot rolling is 60% and the final rolling temperature is 850~900 ℃. After hot rolling, the plate is immediately water-cooled.

[0067] (3) The hot-rolled sheet obtained after step (2) is subjected to solution treatment at a temperature of 900 ℃ and a holding time of 4 h. After solution treatment, the sheet is water-cooled.

[0068] (4) The sheet obtained after step (3) is subjected to a first cold rolling process with a deformation of 50%.

[0069] (5) The board obtained after step (4) is subjected to the first aging treatment. The temperature of the first aging treatment is 500℃ and the heat preservation time is 10 h. After the aging treatment, the board is water-cooled.

[0070] (6) The aged sheet obtained after step (5) is subjected to a second cold rolling process with a deformation of 50%.

[0071] (7) The board obtained after step (6) is subjected to a second aging treatment. The temperature of the second aging treatment is 350℃ and the holding time is 2 h. After the aging treatment, the board is water-cooled.

[0072] (8) The aged sheet obtained after step (7) is subjected to a third cold rolling process with a deformation of 50%.

[0073] (9) The plate obtained after step (8) is subjected to a third aging treatment. The temperature of the third aging treatment is 300℃ and the holding time is 1 h. After the aging treatment, the plate is water-cooled to finally obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate.

[0074] The microstructure of the alloy sheet obtained in this embodiment is as follows: Figure 1 and Figure 2 As shown, where Figure 1 The image shows a scanning electron microscope (SEM) image of the tensile fracture surface. Figure 2 This is a transmission electron microscope (TEM) bright-field image.

[0075] like Figure 1 As shown, the CuCoNiSi alloy sheet obtained in this embodiment exhibits typical ductile fracture characteristics dominated by uniform and fine dimples after tensile fracture. The dimples are uniformly distributed in size and have a large depth. No obvious cleavage steps or intergranular fracture characteristics were observed. This indicates that the alloy can still undergo sufficient plastic deformation under high strength conditions and has good energy absorption capacity during fracture, demonstrating the material's excellent plasticity and fracture toughness.

[0076] like Figure 2 As shown, the bright-field transmission electron microscopy image further reveals the microstructure characteristics of the alloy of this invention. It can be observed that high-density, finely dispersed nanoscale precipitates and a small amount of larger-scale precipitates coexist in the copper matrix, exhibiting a distinct multi-scale precipitation structure. The nanoscale precipitates are distributed synergistically with dislocations and deformation substructures, effectively hindering dislocation movement and providing a significant precipitation strengthening effect; while the relatively coarse precipitates help to distribute local stress concentrations and pin dislocations, thereby delaying damage initiation and crack propagation.

[0077] The fracture morphology and transmission electron microscopy (TEM) microstructure results corroborate each other, indicating that the present invention, through the synergistic control of microalloying composition design and multi-stage deformation heat treatment processes, constructs a multi-scale precipitate structure in the alloy that combines high strengthening efficiency with good deformation coordination. This structure not only significantly improves the strength of the alloy but also effectively suppresses early instability and brittle fracture, enabling the material to maintain excellent strength and ductility while retaining high electrical conductivity.

[0078] Example 5: A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy of the present invention comprises the following components by weight percentage: Ni 3.5%, Co 2.0%, Si 1.5%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, wherein the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, and the balance is copper and unavoidable impurities.

[0079] The preparation method of the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy in this embodiment includes the following steps: (1) Prepare the raw materials according to the weight percentage of the element composition. Put the electrolytic copper block, nickel granules, cobalt granules, iron granules and silver granules into the heating furnace, heat to 1500 ℃ to melt the raw materials, then add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon granules, and finally add zirconium granules and magnesium granules. After they are completely melted, keep them at 1300 ℃ for 30 min, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot; (2) The ingot obtained after step (1) is homogenized at a temperature of 980 ℃ and held for 6 h. After homogenization, hot rolling is performed immediately. The deformation of hot rolling is 80% and the final rolling temperature is 850~900 ℃. After hot rolling, the plate is immediately water-cooled.

[0080] (3) The hot-rolled sheet obtained after step (2) is subjected to solution treatment at a temperature of 980 ℃ and a holding time of 4 h. After solution treatment, the sheet is water-cooled.

[0081] (4) The sheet obtained after step (3) is subjected to a first cold rolling process with a deformation of 60%.

[0082] (5) The board obtained after step (4) is subjected to the first aging treatment. The temperature of the first aging treatment is 450℃ and the heat preservation time is 8 h. After the aging treatment, the board is water-cooled.

[0083] (6) The aged sheet obtained after step (5) is subjected to a second cold rolling process with a deformation of 60%.

[0084] (7) The board obtained after step (6) is subjected to a second aging treatment. The temperature of the second aging treatment is 400℃ and the holding time is 1 h. After the aging treatment, the board is water-cooled.

[0085] (8) The aged sheet obtained after step (7) is subjected to a third cold rolling process with a deformation of 80%.

[0086] (9) The plate obtained after step (8) is subjected to a third aging treatment. The temperature of the third aging treatment is 350℃ and the holding time is 0.5 h. After the aging treatment, the plate is water-cooled to finally obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy plate.

[0087] Comparative Example 1: Nickel content too low The CuCoNiSi alloy sheet of this comparative example contains the following components by weight percentage: Ni 0.5%, Co 2.5%, Si 0.5%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, of which the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, with the balance being copper and unavoidable impurities.

[0088] The CuCoNiSi alloy plate in this comparative example differs from that in Example 1 only in its alloy composition; its preparation method is exactly the same as that in Example 1.

[0089] Comparative Example 2: Excessive Nickel Content The CuCoNiSi alloy sheet of this comparative example contains the following components by weight percentage: Ni 10.0%, Co 1.5%, Si 0.8%, Cr 0.15%, Fe 0.1%, Zr 0.1%, Mg 0.05%, Ag 0.05%, and V 0.05%, of which the total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.5%, with the balance being copper and unavoidable impurities.

[0090] The only difference between the CuCoNiSi alloy plate in this comparative example and Example 2 is the alloy composition; the preparation method is exactly the same as that in Example 2.

[0091] Comparative Example 3: Solution temperature too high The CuCoNiSi alloy plate of this comparative example has the same alloy composition as that of Example 3. The difference between the preparation method of the CuCoNiSi alloy plate of this comparative example and that of Example 3 is that the solution treatment temperature in step (3) is 1020℃, and the other process flow and corresponding process parameters are the same as those of Example 3.

[0092] Comparative Example 4: No third cold rolling treatment and no third aging treatment. The CuCoNiSi alloy sheet of this comparative example has the same alloy composition as that of Example 4. The difference between the preparation method of the CuCoNiSi alloy sheet of this comparative example and that of Example 4 is that the sheet obtained in step (7) is the final CuCoNiSi alloy sheet, that is, no third cold rolling treatment and third aging treatment are performed.

[0093] Comparative Example 5: No Co or trace elements added The CuCoNiSi alloy sheet of this comparative example comprises, by weight percentage: Ni 3.5%, Si 1.5%, with the balance being copper and unavoidable impurities.

[0094] The only difference between the CuCoNiSi alloy plate of this comparative example and Example 5 is the alloy composition. The heat treatment process of the alloy ingot in its preparation method is exactly the same as that in Example 5.

[0095] At room temperature, tensile tests and conductivity tests were performed on the high-strength, high-conductivity CuCoNiSi alloy plates prepared in the above embodiments and comparative examples. The test results are shown in Table 1.

[0096] Table 1. Properties of CuCoNiSi alloy plates prepared in each embodiment and comparative example.

[0097] As shown in Table 1, the experimental results of Comparative Example 1 and Example 1 indicate that when the Ni content is too low, the mechanical properties of the alloy decrease significantly, indicating that Ni is the key element for forming the main strengthening phase (Ni, Co)₂Si. When the absolute Ni content is below a certain threshold, even if (Ni + Co) / Si is within the range defined by this invention, due to the insufficient number of Ni atoms that can participate in precipitation, it is still difficult to form a sufficient volume fraction of (Ni, Co)₂Si precipitate, thus failing to achieve the desired strengthening effect. The experimental results of Comparative Example 2 and Example 2 indicate that when the Ni content is too high, (Ni + Co) / Si exceeds the range of this invention, and the electrical conductivity of the alloy deteriorates significantly, indicating that excessive Ni atoms dissolved in the copper matrix enhance electron scattering, adversely affecting electrical conductivity. The experimental results of Comparative Example 3 and Example 3 show that when the solution treatment temperature exceeds the reasonable upper limit of 980 °C, although the temperature increase is limited, this temperature is close to the critical region for solution treatment of CuCoNiSi alloys, which is not conducive to the stable control of grain size and weakens the pinning effect of microalloying elements such as Cr and Zr on grain boundaries and dislocations, thus affecting the stability of the solid solution structure. Simultaneously, excessively high solution temperatures are not conducive to the uniform nucleation and size control of (Ni, Co)₂Si precipitates during subsequent aging, leading to a reduction in the number of precipitates and their tendency to coarsen, resulting in a simultaneous decrease in the alloy's strength, conductivity, and strength-ductility product. The experimental results of Comparative Example 4 and Example 4 show that when only two cold rolling-aging treatments are performed, without a third cold rolling and aging treatment, the strength and strength-ductility product of the alloy sheet both decrease, indicating that multi-pass cold rolling-aging treatment plays an important role in obtaining excellent comprehensive performance. The experimental results of Comparative Example 5 and Example 5 show that the strength and conductivity of the alloy significantly decrease when no Co or trace elements such as Cr, Fe, and Zr are added to the composition. This result indicates that the appropriate introduction of Co and elements such as Cr, Fe, and Zr is beneficial to improving the overall performance of the alloy. Specifically, the addition of Co promotes the formation of the (Ni, Co)₂Si precipitate, while trace elements such as Cr, Fe, and Zr, by regulating the evolution behavior of the precipitate, inhibit precipitate coarsening and stabilize the microstructure, thereby synergistically enhancing the precipitation strengthening effect and achieving an overall improvement in the alloy's comprehensive performance.

[0098] In summary, the high-strength, high-conductivity, and high-ductility CuCoNiSi alloy plates prepared using the process and parameters of this invention can achieve excellent comprehensive performance, with a conductivity of not less than 50% IACS, a tensile strength of not less than 700 MPa, and a strength-ductility product of not less than 9 GPa·s.

Claims

1. A high-strength, high-conductivity, and high-ductility CuCoNiSi alloy, characterized in that, The alloy comprises the following components by weight percentage: Ni 1.0-3.5%, Co 1.0-2.5%, Si 0.5-1.5%, Cr 0.01-0.3%, Fe 0.01-0.3%, Zr 0.01-0.3%, Mg 0.01-0.3%, Ag 0.01-0.3%, V 0.01-0.3%, balance being copper and unavoidable impurities.

2. The high-strength, high-conductivity, and high-ductility CuCoNiSi alloy as described in claim 1, characterized in that, The total weight percentage of Cr, Fe, Zr, Mg, Ag, and V is 0.1-0.5%.

3. The high-strength, high-conductivity, and high-ductility CuCoNiSi alloy as described in claim 2, characterized in that, The (Ni + Co) / Si mass ratio is controlled between 3.0 and 7.

0.

4. The high-strength, high-conductivity, and high-ductility CuCoNiSi alloy as described in claim 1, characterized in that, The high-strength, high-conductivity, and high-ductility CuCoNiSi alloy has a conductivity of not less than 50% IACS, a tensile strength of not less than 700 MPa, and a strength-ductility product of not less than 9.00 GPa·s.

5. A method for preparing a high-strength, high-conductivity, and high-ductility CuCoNiSi alloy as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Prepare materials according to the weight percentage of the element composition, put copper, nickel, cobalt, iron and silver raw materials into the heating furnace to melt, add copper-chromium master alloy and copper-vanadium master alloy to the molten pool, then add silicon raw materials, and finally add zirconium raw materials and magnesium raw materials. After they are completely melted, keep them warm and stir, then pour the melt into the mold, and after cooling, obtain CuCoNiSi alloy ingot. (2) The CuCoNiSi alloy ingot is subjected to homogenization treatment, hot rolling treatment, solution treatment, first cold rolling treatment, first aging treatment, second cold rolling treatment, second aging treatment, third cold rolling treatment, and third aging treatment in sequence to obtain a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy.

6. The preparation method according to claim 5, characterized in that, In step (1), the melting temperature is controlled at 1300-1500 ℃, the holding temperature is controlled at 1100-1300 ℃, and the holding time is controlled at 10-30 min.

7. The preparation method according to claim 5, characterized in that, In step (2), the homogenization treatment temperature is 900-980 ℃ and the holding time is 4-8 h.

8. The preparation method according to claim 5, characterized in that, In step (2), the deformation of the hot rolling process is 50-80%, the final hot rolling temperature is 850-900 ℃, and the plate is immediately water-cooled after the hot rolling process; The solution treatment temperature is 900-980 ℃, the holding time is 4-8 h, and the board is water-cooled after the solution treatment.

9. The preparation method according to claim 5, characterized in that, In step (2), the deformation amount of the first cold rolling process is 50-80%; The temperature of the first aging treatment is 450-500 ℃, the aging holding time is 2-10 h, and the board is water-cooled after the aging treatment. The deformation amount of the second cold rolling process is 50%-80%; The temperature of the second aging treatment is 350-400 ℃, the aging holding time is 1-5 h, and the board is water-cooled after the aging treatment. The deformation amount of the third cold rolling process is 50-80%; The third aging treatment is performed at a temperature of 300-350 ℃, with an aging holding time of 0.5-2 h. After the aging treatment, the board is water-cooled.

10. The application of a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy as described in any one of claims 1 to 4, or a high-strength, high-conductivity, and high-plasticity CuCoNiSi alloy prepared by the preparation method as described in any one of claims 5 to 9, in connectors, lead frames, relay contacts, electrical contacts, elastic conductive elements, and conductive connection structures.

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