High-strength and high-conductivity Cu-Zr-Cr alloy and preparation method thereof

Abstract

The application discloses a kind of high-strength high-conductivity Cu-Zr-Cr alloy and preparation method thereof, belong to copper alloy material technical field.The alloy includes:Zr 0.4%~0.6%, Cr 0.3%~0.5%, the balance is Cu and inevitable impurities by weight percentage.Its preparation method includes: batching, vacuum induction electromagnetic levitation melting and solidification, annealing treatment, cold rolling deformation, aging treatment, ultrasonic vibration under ultralow temperature condition is treated in coordination with alternating magnetic field and low-temperature annealing treatment.The application is optimized by component design and multi-step process coordination, especially introduce ultrasonic vibration under ultralow temperature condition is treated in coordination with alternating magnetic field, successfully constructs high-density nanotwin and the composite strengthening structure of dispersed distribution nanoscale precipitated phase in alloy, realizes the collaborative promotion of strength and conductivity.The process route is clear, parameter controllable, good repeatability, solves the problem that traditional Cu-Zr series alloy strength and conductivity are difficult to consider, is suitable for the large-scale preparation and application of high-performance copper alloy.

Description

Technical Field

[0001] This invention relates to the field of copper alloy materials, specifically a high-strength, high-conductivity Cu-Zr-Cr alloy and its preparation method. Background Technology

[0002] With the rapid development of high-speed rail, power electronics, 5G communications, and high-end equipment manufacturing, more stringent requirements have been placed on copper alloy materials to simultaneously possess high strength and high conductivity during service. Especially under high current density, high mechanical load, and complex service environments, traditional copper alloy systems struggle to achieve synergistic optimization among strength, conductivity, and structural stability, and are gradually failing to meet the demands of next-generation applications.

[0003] Currently, Cu-Be alloys are widely used due to their excellent comprehensive properties. However, the significant toxicity of Be (Be) has led to strict restrictions, necessitating the development of alternative copper alloy systems with comparable performance that are non-toxic and environmentally friendly. Cu-Cr alloys, as typical age-hardening copper alloys, possess both high strength and good electrical conductivity, and are considered important candidates for replacing Cu-Be alloys. However, existing Cu-Cr binary alloys are prone to coarsening and uneven distribution of precipitates during aging, leading to a decline in strengthening effect and difficulty in maintaining mechanical properties and thermal stability over long periods, severely restricting their application in high-end fields.

[0004] To address these issues, researchers typically introduce Zr, Mg, Ti, Ni, Si, or rare earth elements into Cu-Cr alloys through microalloying to regulate precipitation behavior and microstructure stability. Among these, trace amounts of Zr can promote nucleation of precipitates, inhibit their coarsening, and refine the precipitate spacing, thus improving alloy strength and thermal stability to some extent. However, the introduction of multiple alloying elements inevitably enhances electron scattering effects, easily leading to a decrease in conductivity, creating a technical bottleneck where improving alloy performance faces the challenge of balancing strength and conductivity.

[0005] Recent studies have shown that constructing high-density nanotwin structures in copper alloys is an effective way to overcome the limitations of traditional strengthening mechanisms. Coherent nanotwin boundaries can not only significantly hinder dislocation movement and improve material strength, but also have low interface energy and electron scattering ability, which is beneficial for maintaining high conductivity. However, the introduction of nanotwin structures into Cu-Zr-Cr alloys in existing technologies usually relies on severe plastic deformation or complex processing paths, resulting in insufficient microstructure uniformity and stability, and making it difficult to achieve controllable adjustment while ensuring high conductivity.

[0006] Therefore, how to introduce a stable and controllable nanotwin structure through reasonable melting and multi-field coupling control methods, while ensuring the controllability of Cu-Zr-Cr alloy composition and uniform microstructure, and achieve the synergistic improvement of high strength, high conductivity and microstructure stability, remains a key technical problem that needs to be solved by existing technologies. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength and high-conductivity Cu-Zr-Cr alloy and its preparation method, so as to solve the technical problems of easy coarsening of precipitated phases (including Cr phase and CuZr phase) in existing Cu-Zr-Cr alloys during aging, insufficient microstructure stability, decreased conductivity caused by microalloying, and difficulty in balancing strength and conductivity.

[0008] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0009] On one hand, the present invention provides a method for preparing a high-strength, high-conductivity Cu-Zr-Cr alloy, wherein the chemical composition of the alloy, by weight percentage, is: Zr 0.4%–0.6%, Cr 0.3%–0.5%, with the balance being Cu and unavoidable impurities; it is prepared by the following method:

[0010] Step S1: Weigh out Cu raw materials, Zr raw materials, and Cr raw materials according to the above alloy composition;

[0011] Step S2: Place the prepared raw materials in a first electromagnetic field for vacuum induction electromagnetic levitation melting; the first electromagnetic field can suspend and melt the raw materials to obtain a uniform alloy melt; then, drop the alloy melt into a gas-cooled crystallizer and apply a second electromagnetic field on its drop path to stabilize the falling trajectory and achieve uniform cooling. After solidification, an alloy ingot is obtained.

[0012] Step S3: Anneal the alloy ingot to eliminate internal stress and homogenize the microstructure to obtain the alloy;

[0013] Step S4: Perform multi-pass cold rolling deformation on the alloy to introduce high-density dislocations;

[0014] Step S5: The cold-rolled and deformed alloy is subjected to aging treatment to obtain a dispersed nanoscale precipitate phase.

[0015] Step S6: Place the aged alloy at liquid nitrogen temperature and simultaneously apply ultrasonic vibration at a frequency of 15kHz and an alternating magnetic field with a constant direction to induce the formation of a high-density nanotwin structure.

[0016] The alternating magnetic field is applied in the following manner:

[0017] (1) Apply an electric current to excite the magnetic field, causing the magnetic field strength to increase linearly from 0 to 2T within 0.1-5 seconds;

[0018] (2) Cut off the current and keep it off for 0.1-5 seconds to reduce the magnetic field strength to 0;

[0019] (3) Repeat steps (1) and (2) to form a periodically changing magnetic field;

[0020] Step S7: Perform low-temperature annealing on the alloy treated in step S6 to obtain a high-strength, high-conductivity Cu-Zr-Cr alloy.

[0021] Furthermore, in step S2, the first electromagnetic field is a high-frequency alternating electromagnetic field with a frequency of 300kHz and a magnetic field strength of 0.3T.

[0022] Furthermore, in step S2, the second electromagnetic field is a low-frequency alternating electromagnetic field with a frequency of 50Hz and a magnetic field strength of 0.1T.

[0023] Furthermore, in step S2, the specific method for preparing the alloy melt is as follows: evacuate the furnace to a vacuum level of 5 × 10⁻⁶. -4 Below Pa, Cu raw material is suspended in the first electromagnetic field. The temperature is first raised to 1100℃ to melt Cu, then Cr raw material and Zr raw material are added. The temperature is then raised to 1250-1300℃ and kept at that temperature while stirring for 5-10 minutes to completely melt the alloy, thus obtaining a uniform alloy melt.

[0024] Furthermore, in step S3, the annealing temperature is 800°C and the holding time is 2 hours.

[0025] Furthermore, in step S4, the total deformation of the multi-pass cold rolling deformation is 80%, and the deformation of a single pass does not exceed 50%.

[0026] Furthermore, in step S5, the aging treatment temperature is 400–500°C, and the holding time is 60–120 minutes.

[0027] Furthermore, in step S6, the duration of the combined treatment of ultrasonic vibration and alternating magnetic field is 1 to 2 hours.

[0028] Furthermore, in step S7, the temperature of the low-temperature annealing treatment is 200°C, and the holding time is 1 hour.

[0029] On the other hand, the present invention provides a high-strength, high-conductivity Cu-Zr-Cr alloy, which is prepared by the above-described method.

[0030] This invention introduces appropriate amounts of Zr and Cr elements into a Cu matrix through reasonable composition design. The roles of Zr and Cr elements in the alloy are explained below.

[0031] Zr content (0.4%–0.6% by weight): When the Zr content is below 0.4 wt.%, the number of Zr atoms is insufficient, making it difficult to form a continuous and effective segregated layer at the precipitate interface and grain boundaries. This limits the inhibitory effect on precipitate coarsening, and the strengthening effect decays rapidly after aging. When the Zr content is above 0.6 wt.%, excess Zr exists in the Cu matrix in solid solution form, strongly increasing electron scattering and significantly reducing conductivity, thus undermining the goal of high conductivity. Furthermore, excess Zr easily forms Cu-Zr intermetallic compounds or coarse precipitates, which are detrimental to plastic deformation and increase the risk of cold rolling cracking. Therefore, this invention controls the Zr content at 0.4–0.6 wt.%, which effectively inhibits precipitate coarsening and improves the thermal stability of the microstructure while avoiding the significant decrease in conductivity and microstructure embrittlement caused by excess Zr, achieving a synergistic optimization of strength and conductivity.

[0032] Cr (by weight, 0.3%–0.5%): When the Cr content is below 0.3 wt.%, precipitation strengthening is insufficient and cannot meet the high strength requirements. When the Cr content is above 0.5 wt.%, the precipitated phase tends to grow during aging, and the amount of residual dissolved Cr in the matrix increases before and after aging, leading to enhanced electron scattering and decreased conductivity. Therefore, this invention controls the Cr content at 0.3–0.5 wt.%, which can achieve significant precipitation strengthening while avoiding the decrease in conductivity caused by coarsening of the precipitated phase and increased dissolved Cr, thus facilitating a balance between high strength and high conductivity.

[0033] The principle of this invention is explained as follows: (1) This invention introduces appropriate amounts of Zr and Cr elements into the Cu matrix through reasonable composition design, and combines vacuum induction electromagnetic levitation melting technology to achieve the purification and homogenization control of the alloy melt under crucible-free conditions. The first electromagnetic field is used to suspend and fully stir the melt, effectively avoiding impurity contamination and compositional segregation. Combined with the gas-cooled crystallization process, a dense and uniform alloy ingot is obtained under the assistance of the second electromagnetic field, providing a good initial microstructure foundation for subsequent microstructure control. (2) On this basis, this invention sequentially performs annealing, cold rolling deformation and aging treatment on the alloy, and controls the dislocation density and precipitation behavior through the deformation-aging synergistic effect, thereby improving the alloy strength without significantly sacrificing the conductivity. Meanwhile, in order to further break through the performance bottleneck of traditional precipitation strengthening and deformation strengthening, this invention introduces an ultrasonic vibration synergistic alternating magnetic field treatment process under ultra-low temperature conditions. In this process, ultrasonic vibration introduces high-frequency alternating stress inside the material, promoting dislocation slip, dislocation entanglement and twin nucleation. The alternating magnetic field is achieved by periodically switching on and off the excitation current, so that the sample undergoes an alternating process of magnetic field "loading-unloading-reloading". The core of this process is the energy state disturbance caused by the switching on and off of the magnetic field, which promotes dislocation depinning through the magnetoplastic effect, and finally twin nucleation. The synergistic effect of ultrasound and alternating magnetic field enhances the uniformity of defect evolution and spatial distribution consistency, and forms nanotwin structures with diverse orientations and uniform distribution without significantly increasing processing energy consumption. (3) Subsequently, the formed structure is stabilized and regulated by low-temperature annealing treatment, which maintains the stable existence of the nanotwin structure while inhibiting the recovery and coarsening of the structure. The obtained nanotwin structure has coherent nanotwin interface characteristics, which can effectively hinder dislocation movement and improve material strength. At the same time, its low interface energy and low electron scattering characteristics are conducive to maintaining high conductivity, thereby achieving a synergistic improvement of high strength, high conductivity and good structural stability.

[0034] Beneficial effects:

[0035] (1) This invention, through composition and process optimization, simultaneously constructs a composite structure of high-density nanotwins and dispersed nanoscale precipitates in the alloy. Among them, the nanotwins, especially their coherent interfaces, significantly hinder dislocation movement and improve strength, while maintaining high conductivity to the greatest extent due to their extremely low interface energy and electron scattering characteristics; while the addition of Zr effectively suppresses the coarsening of precipitates and reduces solid solution atom scattering. The synergy of the two enables the alloy to achieve high strength (tensile strength up to 747.5 MPa) while maintaining excellent conductivity (conductivity 77.1% IACS), successfully solving the problem of the difficulty in achieving both high strength and conductivity in Cu-Zr alloys.

[0036] (2) This invention utilizes a vacuum induction electromagnetic levitation melting process to prepare alloy ingots. Vacuum induction electromagnetic levitation melting avoids crucible contamination, and electromagnetic stirring ensures highly uniform composition, resulting in a clean and uniform alloy ingot structure from the source. The addition of Zr effectively suppresses the coarsening of precipitated phases during aging and improves the thermal stability of the structure. The nanotwin structure induced by ultrasonic vibration combined with alternating magnetic field treatment under ultra-low temperature conditions is uniformly distributed, and subsequent low-temperature annealing further stabilizes this structure, giving the alloy good long-term service stability.

[0037] (3) The process route of this invention is clear, the parameters of each step are controllable, and the repeatability is strong. The steps of vacuum induction electromagnetic levitation melting, cold rolling deformation, aging, ultrasonic vibration combined with alternating magnetic field treatment under ultra-low temperature conditions, and low temperature annealing are closely linked and have a clear synergistic effect. Compared with the traditional method that relies on severe plastic deformation to introduce nanotwins, this method achieves controllable construction of the structure with lower energy consumption through physical field coupling. The process flow is relatively short and more suitable for the engineering preparation and application promotion of high-performance Cu-Zr-Cr copper alloys.

[0038] (4) The alloy system of the present invention is completely free of toxic Be element, and uses Zr and Cr as alloying elements. The raw materials are readily available, the preparation process has low environmental risk, and it is in line with the development trend of green manufacturing. It is an ideal environmentally friendly alternative material for Cu-Be alloy. Attached Figure Description

[0039] Figure 1 The images show the TEM bright-field microstructure of the Cu-Zr-Cr alloy prepared in Example 1 of this invention. (a) mainly shows the dispersed nanoscale precipitates, and (b) mainly shows the nanotwin structure. Detailed Implementation

[0040] First, the technical solution of the present invention will be described in detail.

[0041] This invention provides a high-strength, high-conductivity Cu-Zr-Cr alloy and its preparation method. The alloy, by weight percentage, has the following chemical composition: Zr 0.4%–0.6%, Cr 0.3%–0.5%, with the balance being Cu and unavoidable impurities. This composition design is based on the following considerations: when the Zr content is below 0.4%, its inhibitory effect on precipitate coarsening is limited; above 0.6%, it significantly increases electron scattering, impairing conductivity and potentially causing brittleness. When the Cr content is below 0.3%, precipitation strengthening is insufficient; above 0.5%, it easily leads to precipitate coarsening and an increase in solid solution atoms, similarly reducing conductivity. Controlling the Zr and Cr contents within this optimized range aims to achieve the best synergy between strength and conductivity.

[0042] The alloy is prepared through the following steps, and the specific operation methods for each step are as follows:

[0043] Step S1 (Ingredients): Weigh out Cu raw materials (such as copper particles), Zr raw materials (such as zirconium blocks), and Cr raw materials (such as chromium blocks) with a purity ≥ 99.99% according to the above alloy composition; this step is a prerequisite for ensuring the accuracy of the final alloy composition.

[0044] Step S2 (Vacuum Induction Electromagnetic Levitation Melting and Solidification): The prepared raw materials are subjected to vacuum induction electromagnetic levitation melting; specific operations include: first, evacuating the furnace to a vacuum of 5×10 -4 The pressure is below 1 Pa, then high-purity argon gas (≥99.999%) is introduced. This vacuuming-gas-filling process can be repeated 2-3 times to effectively remove residual oxygen, water vapor, and other impurities, reduce oxygen partial pressure, and ensure a pure vacuum environment. The Cu raw material is placed in a first electromagnetic field (preferably a high-frequency alternating electromagnetic field with a frequency of 300 kHz and a magnetic field strength of 0.3 T) generated by a high-frequency induction coil. The first electromagnetic field is activated, and the Cu raw material is suspended under the action of electromagnetic force. The temperature is raised to about 1100℃ to melt the Cu. Then, Cr and Zr raw materials are gradually added, and the temperature is further raised to 1250-1100℃. The alloy is stirred at 300℃ for 5-10 minutes using a strong electromagnetic field to ensure complete homogenization of the alloy composition. After obtaining the alloy melt, it is allowed to drip into a lower air-cooled crystallizer. A second electromagnetic field (preferably a low-frequency alternating electromagnetic field with a frequency of 50Hz and a magnetic field strength of 0.1T) is applied along the path of the dripping melt to stabilize its trajectory, suppress splashing and oscillation, and promote uniform cooling and solidification, ultimately obtaining a dense, homogeneous alloy ingot. This step is one of the core components of this invention, achieving high-cleanliness, pollution-free melting and uniform solidification of the alloy.

[0045] Step S3 (annealing): The alloy ingot obtained in step S2 is annealed to obtain the alloy. The specific operation is usually as follows: the ingot is placed in a heating furnace under air or a protective atmosphere, heated to 800°C and held for 2 hours, and then cooled in the furnace or air-cooled. This process aims to eliminate the internal stress of the alloy ingot, homogenize the microstructure, and prepare for subsequent plastic deformation.

[0046] Step S4 (Cold Rolling Deformation): The annealed alloy is subjected to plastic processing, specifically using a multi-pass cold rolling deformation process, with a total deformation amount reaching 80%, and the deformation amount of a single pass is controlled to not exceed 50% to prevent cracking; this step aims to introduce high-density deformation defects such as dislocations and slip bands into the alloy, providing driving force and nucleation sites for subsequent precipitate nucleation and twin formation;

[0047] Step S5 (Aging Treatment): The cold-rolled alloy is aged. Specifically, the alloy is placed in a heat treatment furnace and held at 400–500°C for 60–120 minutes. This process promotes the dispersion of supersaturated solid solution Cr atoms in the Cu matrix as nanoscale precipitates, resulting in a significant precipitation strengthening effect. At the same time, Zr elements in the alloy will agglomerate at the precipitate interface, effectively inhibiting the coarsening of the precipitates during the aging process and improving the thermal stability of the microstructure.

[0048] Step S6 (Ultrasonic Vibration Combined with Alternating Magnetic Field Treatment under Cryogenic Conditions): The aged alloy is placed in a liquid nitrogen environment (-196℃), and ultrasonic vibration and alternating magnetic fields are applied simultaneously for synergistic treatment. Specific parameters are: ultrasonic vibration frequency 15kHz; the alternating magnetic field is achieved by periodically switching the excitation current on and off, with the magnetic field direction remaining constant, and the magnetic field strength changing periodically from 0 to 2T within 0.1-5 seconds, then remaining de-energized for 0.1-5 seconds to reduce the magnetic field strength to 0, and so on, thus subjecting the sample to a periodic magnetic field "loading-unloading" process; the treatment time is typically 1-2 hours; the liquid nitrogen cryogenic environment inhibits atomic diffusion and dynamic recovery; ultrasonic vibration introduces high-frequency stress to promote dislocation movement and recombination; the alternating magnetic field promotes dislocation depinning through the magnetoplastic effect; the three work synergistically to efficiently induce a high-density, uniformly distributed nanotwin structure in the alloy; this step is the core innovation of this invention.

[0049] Step S7 (Low-temperature annealing): Perform final low-temperature annealing on the alloy treated in step S6; the specific operation is usually: hold at 200°C for 1 hour; this step aims to eliminate the local residual internal stress introduced by the previous treatment (especially step S6), stabilize the formed nanotwin and nanoscale precipitate interface structure, suppress their recovery or coarsening, and while maintaining high strength, help to further optimize and stabilize the conductivity.

[0050] Through the organic combination of the above steps, the final Cu-Zr-Cr alloy microstructure contains both high-density nanotwins and dispersed nanoscale precipitates, thus possessing both ultra-high strength and excellent electrical conductivity.

[0051] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments and comparative examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0052] Example 1

[0053] A method for preparing a high-strength, high-conductivity Cu-Zr-Cr alloy includes the following steps:

[0054] Step S1, Ingredients: According to the alloy raw material composition, weigh 0.025 kg of zirconium block, 0.015 kg of chromium block and 4.96 kg of copper particles, with a total weight of 5 kg (corresponding composition: Zr 0.5%, Cr 0.3%, balance Cu).

[0055] Step S2, Vacuum Induction Electromagnetic Suspension Melting and Solidification: Before melting, the furnace is evacuated to a vacuum level of 5×10⁻⁶. -4 Pa, slowly introduce high-purity argon gas (≥99.999%), repeat this vacuuming-gas-filling process 3 times to effectively remove various impurity gases in the furnace; place copper particles in the first electromagnetic field generated by a high-frequency induction coil, apply the first electromagnetic field to generate electromagnetic force, suspend the metallic copper, heat to 1100℃ to melt the copper particles, gradually add zirconium and chromium blocks, further heat to 1300℃ and suspend and stir for 8 minutes until the melt is completely suspended; gently blow high-purity Ar gas on the surface of the suspended melt to remove surface oxides, obtaining a pure alloy melt; then drip the alloy melt into a gas-cooled crystallizer, apply a second electromagnetic field to the drip path to assist the falling to maintain uniform cooling of the melt, and finally form a dense and uniform alloy ingot;

[0056] Step S3, Annealing: Heat the alloy ingot to 800℃ in a box furnace and hold for 2 hours to obtain the alloy;

[0057] Step S4, Cold Rolling Deformation: The annealed alloy sample is subjected to four passes of cold rolling deformation, with a total deformation of 80% and a single pass deformation controlled not to exceed 50%.

[0058] Step S5, Aging treatment: The alloy sample after cold rolling deformation is aged at 450℃ for 60 minutes;

[0059] Step S6: Ultrasonic vibration combined with alternating magnetic field treatment under ultra-low temperature conditions: The aged sample is immersed in liquid nitrogen, and ultrasonic vibration and alternating magnetic field are applied simultaneously at the liquid nitrogen temperature for synergistic treatment; the ultrasonic frequency is 15kHz, and the alternating magnetic field is achieved by periodically switching the excitation current on and off. The direction of the magnetic field remains unchanged, and the period of change of the magnetic field strength is: linearly increasing from 0 to 2T within 3 seconds, and then maintaining the power off state for 3 seconds to reduce the magnetic field strength to 0. This cycle is repeated, and the treatment time is 2 hours.

[0060] Step S7, Low-temperature annealing treatment: The alloy sample treated in step S6 is annealed at 200℃ for 1 hour to obtain the final alloy sample.

[0061] Figure 1This is a bright-field TEM image of the Cu-Zr-Cr alloy prepared in Example 1 of this invention. The image visually reveals the microstructural origins of the alloy's superior properties. Two key structural features can be observed in the TEM image. First, as shown in Figure (a), a large number of fine, nanoscale precipitates (such as Cr-rich phases) are dispersed throughout the Cu matrix. These nanoscale precipitates are mainly formed during aging, and their fine and uniform distribution forms the basis for significant precipitation strengthening. Second, Figure (b) clearly shows a high-density nanotwin structure, appearing as alternating bright and dark stripes. These nanotwin structures are one of the core features of this invention, encompassing coherent twin boundaries (CTB), incoherent twin boundaries (ITB), and defect twinning (DT) regions formed by the interaction of high-density defects (such as dislocations) with twins. Furthermore, fine nanograin structures (NGs) are also formed in some regions. This composite strengthening structure of "dispersed nanoscale precipitates + high-density nanotwins" is the microscopic essence of the alloy obtained in this embodiment, enabling a synergistic improvement in both ultra-high strength and high conductivity. Coherent nanotwin boundaries effectively hinder dislocation movement, providing excellent strengthening effects. Simultaneously, their extremely low interface energy and low electron scattering characteristics minimize the damage to conductivity during the strengthening process. The fine nanoscale precipitates provide additional precipitation strengthening. Together, they form the cornerstone of the alloy's performance.

[0062] Example 2

[0063] The only difference from Example 1 is that the aging treatment temperature in step S5 is 400°C and the holding time is 60 minutes.

[0064] Example 3

[0065] The only difference from Example 1 is that the aging treatment temperature in step S5 is 500°C and the holding time is 60 minutes.

[0066] Example 4

[0067] The only difference from Example 1 is that the aging treatment temperature in step S5 is 450°C and the holding time is 120 minutes.

[0068] Example 5

[0069] The only difference from Example 1 is that the ultrasonic vibration combined with alternating magnetic field treatment time under ultra-low temperature conditions in step S6 is 1 hour.

[0070] Comparative Example 1

[0071] The only difference from Example 1 is that 0.015 kg of zirconium block (corresponding to a Zr content of 0.3%) is weighed in step S1.

[0072] Comparative Example 2

[0073] The only difference from Example 1 is that 0.035 kg of zirconium block (corresponding to a Zr content of 0.7%) is weighed in step S1.

[0074] Comparative Example 3

[0075] The only difference from Example 1 is that in step S1, 0.01 kg of chromium block (corresponding to a Cr content of 0.2%) is weighed.

[0076] Comparative Example 4

[0077] The only difference from Example 1 is that in step S1, 0.03 kg of chromium block (corresponding to 0.6% Cr content) is weighed.

[0078] Comparative Example 5

[0079] The only difference from Example 1 is that the cold rolling deformation in step S4 is not included.

[0080] Performance testing methods and results

[0081] The alloy samples prepared in Examples 1-5 and Comparative Examples 1-5 were tested for hardness, electrical conductivity and tensile properties.

[0082] Hardness test: The hardness of the alloy samples was determined using an HVS-1000 Vickers hardness tester. The load was 500g and the holding time was 10s. Ten points were taken on the surface of each sample and the average value was taken.

[0083] Conductivity test: The conductivity of the alloy samples was tested using a Sigma 2008B1 digital conductivity meter, and the results are expressed as a percentage relative to the International Standard for Annealed Copper (IACS).

[0084] Tensile property test: The tensile strength of the alloy sample was determined using an AG-I-250kN tensile testing machine.

[0085] The test results are shown in Table 1.

[0086] Table 1 Performance test results of the examples and comparative examples

[0087]

[0088] The data in Table 1 are analyzed below: (1) All alloys obtained in Examples 1-5 exhibited excellent hardness, conductivity, and tensile strength. Among them, Example 1 (Zr 0.5%, Cr 0.3%) showed the best combination of comprehensive performance, with its hardness, conductivity, and tensile strength all at the highest level. The properties of Comparative Example 1 (Zr 0.3%) decreased, indicating that insufficient Zr content weakened its inhibitory and strengthening effect on the coarsening of precipitates. The strength and hardness of Comparative Example 2 (Zr 0.6%) were close to those of Example 1, but the conductivity decreased significantly, indicating that excessive Zr solid solution would damage conductivity. The overall performance of Comparative Example 3 (Cr 0.2%) was low, indicating that insufficient Cr content led to insufficient precipitation strengthening. The conductivity of Comparative Example 4 (Cr 0.6%) was the lowest, indicating that excessive Cr would cause enhanced solid solution atom scattering and coarsening of precipitates. The above results demonstrate the necessity of controlling the Zr content at 0.4-0.6% and the Cr content at 0.3-0.5% for synergistic improvement of the alloy's strength and conductivity. (2) The strength, hardness, and conductivity of Comparative Example 5 (without cold rolling deformation) were significantly lower than those of Example 1, indicating that the high-density dislocations introduced by cold rolling deformation are a necessary prerequisite for subsequent aging precipitation and nanotwin formation. This step plays a key role in achieving high performance of the alloy.

[0089] In summary, this invention, through precise compositional design (Zr 0.4-0.6%, Cr 0.3-0.5%) and a comprehensive preparation process including vacuum induction electromagnetic levitation melting, large-deformation cold rolling deformation, aging, and innovative ultrasonic vibration synergistic alternating magnetic field treatment under ultra-low temperature conditions, successfully constructed a uniform and stable composite strengthening structure of "dispersed nanoscale precipitates + high-density nanotwins" in Cu-Zr-Cr alloys. This fundamentally solves the industry problem of balancing strength and conductivity in this type of alloy, resulting in a high-strength and high-conductivity copper alloy with excellent comprehensive performance.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for producing a high-strength high-conductivity Cu-Zr-Cr alloy, characterized by, The chemical composition of the alloy is: Zr 0.4%-0.6%, Cr 0.3%-0.5%, and the balance of Cu and inevitable impurities in percentage by weight; and the alloy is prepared by the following method: Step S1, the Cu raw material, Zr raw material and Cr raw material are weighed according to the alloy composition; Step S2, the prepared raw materials are placed in a first electromagnetic field for vacuum induction electromagnetic levitation melting; the first electromagnetic field can make the raw materials levitate and melt, so as to obtain an alloy melt with uniform composition; then, the alloy melt is dropped into a gas cooling crystallizer, and a second electromagnetic field is applied on the dropping path of the alloy melt to stabilize the falling trajectory and realize uniform cooling, so as to obtain an alloy ingot after solidification; Step S3, annealing treatment is performed on the alloy ingot to eliminate internal stress and homogenize the structure, so as to obtain an alloy; Step S4, the alloy is subjected to multi-pass cold rolling deformation to introduce high-density dislocations; Step S5, the alloy after cold rolling deformation is subjected to aging treatment to obtain a dispersedly distributed nanoscale precipitate phase; Step S6, the alloy after aging treatment is placed in liquid nitrogen at a temperature of 77K, and an ultrasonic vibration with a frequency of 15 kHz and an alternating magnetic field with a constant direction are applied simultaneously to induce the formation of a high-density nanotwin structure; The alternating magnetic field is applied in the following way: (1) energize to linearly increase the magnetic field strength from 0 to 2T within 0.1-5 seconds; (2) cut off the current and keep the power-off state for 0.1-5 seconds to reduce the magnetic field strength to 0; (3) repeat steps (1) and (2) to form a periodically varying magnetic field; Step S7, the alloy after step S6 is subjected to low-temperature annealing treatment to obtain a high-strength and high-conductivity Cu-Zr-Cr alloy.

2. The production method according to claim 1, characterized by, In step S2, the first electromagnetic field is a high-frequency alternating electromagnetic field with a frequency of 300 kHz and a magnetic field strength of 0.3T.

3. The preparation method according to claim 1, characterized in that, In step S2, the second electromagnetic field is a low-frequency alternating electromagnetic field with a frequency of 50 Hz and a magnetic field strength of 0.1T.

4. The preparation method according to claim 1, characterized in that, In step S2, the specific method for preparing the alloy melt is: the furnace is vacuumed to 5x10 -4 At a temperature below 1400°C, the Cu raw material is suspended in the first electromagnetic field, heated to 1100°C to melt the Cu, then the Cr raw material and the Zr raw material are added, and the temperature is continuously increased to 1250-1300°C and kept for 5-10 minutes to completely melt the alloy, thereby obtaining an alloy melt with uniform composition.

5. The preparation method according to claim 1, characterized in that, In step S3, the annealing treatment temperature is 800℃, and the holding time is 2 hours.

6. The method of claim 1, wherein, In step S4, the total deformation amount of the multi-pass cold rolling deformation is 80%, and the single-pass deformation amount is not more than 50%.

7. The preparation method according to claim 1, characterized in that, In step S5, the aging treatment temperature is 400-500℃, and the holding time is 60-120 minutes.

8. The method of claim 1, wherein, In step S6, the ultrasonic vibration and alternating magnetic field are treated for 1-2 hours.

9. The method of claim 1, wherein, In step S7, the low-temperature annealing treatment temperature is 200℃, and the holding time is 1 hour.

10. A high-strength high-conductivity Cu-Zr-Cr alloy, characterized by, Prepared by the preparation method of any one of claims 1-9.

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