High-temperature high-performance Cu-Ni-Co-Si alloy and preparation method and application thereof

Abstract

The invention provides a high-temperature high-performance Cu-Ni-Co-Si series alloy as well as a preparation method and application of the high-temperature high-performance Cu-Ni-Co-Si series alloy. The high-temperature high-performance Cu-Ni-Co-Si series alloy is prepared from the following components in percentage by weight: 1.80 to 3.00 percent of Ni, 0.50 to 1.50 percent of Co, 0.40 to 1.00 percent of Si, 0.05 to 0.4 percent of Mg, 0.05 to 0.40 percent of Ti and the balance of Cu and inevitable impurities. The high-temperature high-performance Cu-Ni-Co-Si alloy is a copper alloy material with excellent mechanical properties and electrical conductivity in a high-temperature environment, and can meet the urgent requirements of the fields of automobiles, rail transit, aerospace and the like on high-performance copper alloys.

Description

Technical Field

[0001] This invention relates to copper alloy technology, and more particularly to a high-temperature, high-performance Cu-Ni-Co-Si alloy, its preparation method, and its applications. Background Technology

[0002] Copper alloys are widely used in power, electronics, transportation, aerospace and other fields. The synergistic improvement of their electrical conductivity, thermal conductivity and mechanical properties is a research hotspot and challenge. With the development of industrial technology, increasingly higher requirements are being placed on the high-temperature service performance of copper alloys, especially in automotive connectors, high-speed railway catenaries, aerospace electronic components and other fields. The materials not only need to have good strength and electrical conductivity, but also excellent high-temperature resistance to ensure that the materials can maintain stable performance in high-temperature environments.

[0003] Traditional Cu-Ni-Si copper alloys, while possessing good mechanical and electrical properties, exhibit significant performance degradation at high temperatures, making them unsuitable for the stringent high-temperature service requirements of modern industry. To address this, researchers have introduced cobalt into traditional Cu-Ni-Si alloys, employing microalloying and precipitation strengthening to significantly improve the alloy's heat resistance and overall performance. However, the compositional design, preparation process, and precipitation strengthening mechanism of Cu-Ni-Co-Si alloys remain unclear, particularly regarding precipitate control, strengthening phase stability, and the evolution of precipitates at high temperatures, presenting numerous technical challenges. Summary of the Invention

[0004] The purpose of this invention is to address the problems of traditional copper alloys mentioned above by proposing a high-temperature, high-performance Cu-Ni-Co-Si alloy. This alloy is a copper alloy material with excellent mechanical properties and electrical conductivity at high temperatures, which can meet the urgent needs of the automotive, rail transportation, and aerospace industries for high-performance copper alloys.

[0005] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a high-temperature high-performance Cu-Ni-Co-Si alloy, comprising the following components: Ni content of 1.80wt% to 3.00wt%, Co content of 0.50wt% to 1.50wt%, Si content of 0.40wt% to 1.00wt%, Mg content of 0.05wt% to 0.4wt%, Ti content of 0.05wt% to 0.40wt%, with the balance being Cu and unavoidable impurities.

[0007] Furthermore, the high-temperature high-performance Cu-Ni-Co-Si alloy comprises the following components: Ni content of 1.80wt% to 2.5wt%, Co content of 0.70wt% to 1.00wt%, Si content of 0.60wt% to 0.85wt%, Mg content of 0.1wt% to 0.30wt%, Ti content of 0.05wt% to 0.20wt%, with the balance being Cu and unavoidable impurities.

[0008] Furthermore, the high-temperature high-performance Cu-Ni-Co-Si alloy has a tensile strength of 850-1000 MPa, an electrical conductivity of 40-48% IACS, and an elongation of 5-10% at room temperature.

[0009] Furthermore, the high-temperature high-performance Cu-Ni-Co-Si alloy achieves tensile strengths of 750-800 MPa, 450-500 MPa, and 250-300 MPa at 300℃, 400℃, and 500℃, respectively, with an elongation of 20% to 30%.

[0010] Another objective of this invention discloses a method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys (alloy plates and strips), comprising melting → homogenization → hot rolling → solution treatment → first cold rolling → first intermediate aging → second cold rolling → second intermediate aging → third cold rolling → final aging, specifically including the following steps:

[0011] (1) Melting: Electrolytic Cu, electrolytic Ni and polycrystalline Si raw materials are put into the melting furnace in proportion. After the furnace body is evacuated, argon gas is backflushed as a protective gas. The temperature is raised to 1250-1300℃ and held for 5-10 minutes. After Cu-Ni-Si is completely melted, Ti particles and Co particles are added in sequence and held for 5-10 minutes. The temperature is lowered to 1200-1250℃ and Cu-Mg master alloy is added and held for 3-5 minutes. Finally, the temperature is lowered to 1100-1150℃ and poured into a preheated steel mold.

[0012] (2) Homogenization treatment: After casting, the riser of the alloy is removed and placed in an argon-protected box heat treatment furnace. It is heated to 900-950℃ and held for 6-12 hours, and then cooled to room temperature in the furnace.

[0013] (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the alloy surface are milled off, and hot rolling is carried out after holding at 800-850℃ for 1-2 hours.

[0014] (4) Solution treatment: The alloy is placed in a box-type heat treatment furnace protected by high-purity argon gas, held at 960-980℃ for 1-2 hours, and then taken out and quickly quenched in cold water.

[0015] (5) One-time cold rolling: After milling away the oxide film defects on the surface of the solid solution sample, the alloy is subjected to one-time cold rolling;

[0016] (6) Intermediate aging: An intermediate aging process is carried out in a tubular furnace, with the aging process being held at 450-550℃ for 1-2 hours.

[0017] (7) Secondary cold rolling;

[0018] (8) Secondary intermediate aging: Secondary intermediate aging is carried out in a tube furnace. The aging process is to hold at 400-500℃ for 1-2 hours.

[0019] (9) Three-stage cold rolling;

[0020] (10) Final aging: Final aging is carried out in a tube furnace at 350-450℃ for 1-20 hours to prepare high-temperature high-performance Cu-Ni-Co-Si alloy.

[0021] Further, in step (1), the purity of electrolytic Cu is >99.95%, the purity of electrolytic Ni is >99.95%, the purity of polycrystalline Si is >99.99%, the purity of Co particles is >99.95%, and the purity of Ti particles is >99.99%.

[0022] Further, the Cu-Mg master alloy in step (1) is a Cu-10Mg master alloy.

[0023] Further, in step (1), Cu-Mg master alloy, Co particles and Ti particles are added through a feeding funnel.

[0024] Furthermore, the preheating temperature of the preheated steel mold in step (1) is 200-300℃.

[0025] Furthermore, the melting furnace described in step (1) is a vacuum medium-frequency induction melting furnace with a vacuum degree of 5.5 × 10⁻⁶. -2 Pa, with a power of 5 to 15 kW.

[0026] Furthermore, the preferred heat preservation temperature in step (3) is 850°C, and the heat preservation time is 1 hour.

[0027] Further, in step (3), the total deformation of hot rolling is 30-40%, and the deformation per pass is controlled at 5%-10%; the final rolling thickness is 28-32 mm, the deformation per pass is 2-3 mm, and the heat preservation time between each rolling pass is 15-20 min.

[0028] Further, in step (5), the first cold rolling is performed by processing the alloy to a thickness of 25-30 mm and then cold rolling it. The thickness after rolling is 11-13 mm and the deformation is 40-60%.

[0029] Furthermore, the secondary cold rolling in step (7) results in a thickness of 5-7 mm and a deformation of 40-60%.

[0030] Furthermore, the three cold rolling processes described in step (9) result in a thickness of 2-3 mm and a deformation of 40-60%.

[0031] Another objective of this invention is to disclose the application of a high-performance Cu-Ni-Co-Si alloy for high-temperature (above 300°C) service applications. It is particularly suitable for automotive connectors, high-speed railway overhead contact lines, or aerospace electronic components.

[0032] This invention discloses a high-temperature, high-performance Cu-Ni-Co-Si alloy, its preparation method, and its applications. This alloy, by adding trace alloying elements and optimizing the preparation process to traditional Cu-Ni-Co-Si alloys, significantly improves the alloy's overall properties, including strength, electrical conductivity, and plasticity. Compared with existing technologies, this invention has the following key advantages:

[0033] This invention summarizes publicly available performance data of copper alloys using machine learning technology and selects key features using feature engineering. Appropriate algorithms are selected for modeling, and genetic algorithms are used to optimize alloy composition and processing parameters, ultimately determining a precise process route for vacuum induction melting, homogenization, hot rolling, solution treatment, and multi-pass cold rolling and aging.

[0034] This invention successfully modeled and predicted publicly available copper alloy performance data using machine learning methods. Combined with a genetic algorithm, it successfully designed the composition and processing of a novel Cu-Ni-Co-Si alloy, resulting in a Cu-Ni-Co-Si alloy with excellent overall performance. This invention adds trace amounts of alloying elements (Mg and Ti) to the Cu-Ni-Co-Si alloy, significantly improving its overall performance at low cost. The addition of these trace alloying elements (Mg and Ti) promotes the precipitation of precipitates and improves the alloy's high-temperature performance; high-temperature tensile tests revealed that it maintains high strength even at high temperatures.

[0035] This high-temperature, high-performance Cu-Ni-Co-Si alloy has the following performance characteristics:

[0036] Room temperature properties: tensile strength ≥900MPa, electrical conductivity ≥44% IACS, elongation ≥7%;

[0037] High temperature performance: At 300℃: tensile strength ≥750MPa, elongation ≥20%-30%;

[0038] At 400℃: tensile strength ≥490MPa, elongation ≥20%-30%;

[0039] At 500℃: tensile strength ≥280MPa, elongation ≥20%-30%.

[0040] This invention, through precise control of the composition ratio and preparation process of Cu-Ni-Co-Si alloys, forms fine-sized, uniformly distributed, and thermally stable precipitated strengthening phases, thereby developing a copper alloy material with both excellent mechanical properties and electrical conductivity. This alloy has broad application prospects and industrialization value in fields such as automotive connectors, high-speed railway overhead contact lines, and aerospace electronic components. Attached Figure Description

[0041] Figure 1 Machine learning development process and preparation process flow diagram for high-performance Cu-Ni-Co-Si alloys at high temperatures;

[0042] Figure 2 The stress-strain diagram at room temperature for the high-performance Cu-Ni-Co-Si alloy in Example 1 is shown.

[0043] Figure 3 The high-temperature stress-strain diagram of the high-performance Cu-Ni-Co-Si alloy in Example 1 is shown.

[0044] Figure 4 The room temperature stress-strain diagram of the Cu-Ni-Co-Si alloy under peak aging state in Comparative Example 1 is shown.

[0045] Figure 5 For comparison, here is a high-temperature stress-strain diagram of the Cu-Ni-Co-Si alloy in Example 1;

[0046] Figure 6 The room temperature stress-strain diagram of the Cu-Ni-Co-Si alloy under peak aging state in Comparative Example 2;

[0047] Figure 7 The high-temperature stress-strain diagram is for the Cu-Ni-Co-Si alloy of Comparative Example 2.

[0048] Figure 8 The room temperature stress-strain diagram of the Cu-Ni-Co-Si alloy under peak aging state in Comparative Example 2;

[0049] Figure 9 The high-temperature stress-strain diagram is for the Cu-Ni-Co-Si alloy of Comparative Example 2. Detailed Implementation

[0050] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0051] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0052] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0053] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0054] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0055] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0056] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0057] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0058] Example 1

[0059] This example provides a high-temperature, high-performance Cu-Ni-Co-Si alloy with the specific composition of Cu-2.1Ni-0.8Co-0.74Si-0.22Mg-0.11Ti. Its preparation process is as follows:

[0060] (1) Melting: Electrolytic Cu (purity > 99.95%), electrolytic Ni (purity > 99.95%), and polycrystalline Si (purity > 99.99%) raw materials, prepared in proportion, are placed into a vacuum medium-frequency induction melting furnace. Co, Mg, and Ti elements are added by placing Cu-10Mg master alloy, Co granules (purity > 99.95%), and Ti granules (purity > 99.99%) into a charging funnel. After all raw materials have been placed, the furnace is evacuated to a vacuum of 5 × 10⁻⁶. -3 Pa ~ 7 × 10 -3Pa, and backflushing argon gas as a protective gas, the specific gas pressure at this time is 0.05 Pa. Then the power is changed to 15 kW to raise the furnace body temperature to 1250-1300℃, and it is held for 5-10 min. After the Cu-Ni-Si in the crucible is completely melted, Ti particles and Co particles are added to the molten metal in sequence and held for 5-10 min. Then the power is adjusted to 10 kW to lower the temperature to 1200℃, and then Cu-Mg master alloy is added and held for 3 min. Finally, the power is adjusted to 5 kW to lower the temperature to 1100-1150℃, and then the liquid Cu-Ni-Co-Si alloy is poured into a preheated steel mold.

[0061] (2) Homogenization treatment: After removing the riser from the cast Cu-Ni-Co-Si alloy, place it in an argon-protected box-type heat treatment furnace, heat it to 900°C and hold it for 6 hours, and then cool it to room temperature.

[0062] (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the homogenized sample surface are removed by milling machine. After holding at 850℃ for 1 hour, hot rolling is performed. The total deformation is 40%. The deformation of each hot rolling pass is controlled at 5% to 10%. The sample is held for 15 minutes between each hot rolling pass. The final sample thickness is 28 mm.

[0063] (4) Solution treatment: The Cu-Ni-Co-Si alloy was placed in a box-type heat treatment furnace protected by high-purity argon gas and held at 960℃ for 2 hours. After the sample was taken out, it was quickly placed in cold water for quenching.

[0064] (5) Cold rolling in one step: After milling off the oxide film defects on the surface of the solid solution sample with a milling machine, the alloy thickness is processed to 25 mm, and then cold rolling is performed. The thickness after rolling is 12.5 mm and the deformation is 50%.

[0065] (6) Intermediate aging: tubular furnace aging, the specific process is aging at 500℃ for 1 hour;

[0066] (7) Secondary cold rolling: The thickness after cold rolling is 6.25 mm, and the deformation is 50%.

[0067] (8) Secondary intermediate aging: tubular furnace aging, the specific process is aging at 450℃ for 1 hour;

[0068] (9) Three-stage cold rolling: The thickness after cold rolling is 2.5 mm, and the deformation is 60%;

[0069] (10) Final aging: tube furnace aging, the specific process is aging at 400℃ for 1 to 20 hours to prepare high-temperature high-performance Cu-Ni-Co-Si alloy plates and strips.

[0070] The high-performance Cu-Ni-Co-Si alloy sheet and strip from Example 1 at high temperatures were tested. The test methods and results are as follows:

[0071] High-temperature tensile testing: During the high-temperature tensile tests at 300, 400, and 500℃, thermocouples were used to precisely control the temperature, with the temperature error controlled within 5℃. A contact extensometer was used, and the tensile specimen dimensions and tensile parameters were consistent with those of the room-temperature tensile test. After the sample was placed in the thermocouple and kept at that temperature for 10 minutes, the test began, and the tensile test was repeated 3 times at each temperature.

[0072] The alloy was subjected to room temperature tensile testing, and the results are as follows: Figure 2 As shown. According to Figure 2 The tensile curves show that the tensile strength is ≥900MPa and the elongation after fracture is ≥7%. The specific properties of the prepared alloy under different aging parameters are summarized in Table 1.

[0073] High-temperature tensile tests were conducted on high-performance Cu-Ni-Co-Si alloys, and the results are as follows: Figure 3 As shown. According to Figure 3 The tensile curves show that the tensile strength at 300℃ is ≥750MPa and the elongation after fracture is ≥20%; the tensile strength at 400℃ is ≥490MPa and the elongation after fracture is ≥30%; and the tensile strength at 500℃ is ≥280MPa and the elongation after fracture is ≥30%.

[0074] Table 1. Summary of the performance of high-performance Cu-Ni-Co-Si alloys at high temperatures under different aging parameters.

[0075] Aging temperature (°C) Delivery time (h) Tensile strength (MPa) Electrical conductivity (%IACS) Elongation (%) 400 1 903.5 43.02 7.6 400 2 911.4 44.37 7.3 400 4 878.0 45.03 8.6 400 16 881.5 47.42 9.2

[0076] Compare with Example 1

[0077] This comparative example provides a Cu-Ni-Co-Si alloy with the specific composition of Cu-2.1Ni-1.18Co-0.74Si-0.16Mg-0.1Cr, and its preparation process is as follows:

[0078] (1) Melting: Electrolytic Cu (purity > 99.95%), electrolytic Ni (purity > 99.95%), and polycrystalline Si (purity > 99.99%) raw materials, prepared in proportion, are placed into a vacuum medium-frequency induction melting furnace. Co, Mg, and Ti elements are added by placing Cu-10Mg master alloy, Co granules (purity > 99.95%), and Cr granules (purity > 99.99%) into a charging funnel. After all raw materials have been placed, the furnace is evacuated to a vacuum of 5 × 10⁻⁶. -3 Pa ~ 7 × 10 -3Pa, and backflushing argon gas as a protective gas, the specific pressure at this time is 0.05 Pa. Then the power is changed to 15 kW to raise the furnace body temperature to 1250-1300℃, and it is held for 5-10 min. After the Cu-Ni-Si in the crucible is completely melted, Cr particles and Co particles are added to the molten metal in sequence and held for 5-10 min. Then the power is adjusted to 10 kW to lower the temperature to 1200℃, and then Cu-Mg master alloy is added and held for 3 min. Finally, the power is adjusted to 5 kW to lower the temperature to 1100-1150℃, and then the liquid Cu-Ni-Co-Si alloy is poured into a preheated steel mold.

[0079] (2) Homogenization treatment: After removing the riser from the cast Cu-Ni-Co-Si alloy, place it in an argon-protected box-type heat treatment furnace, heat it to 900°C and hold it for 6 hours, and then cool it to room temperature.

[0080] (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the homogenized sample surface are removed by milling machine. After holding at 850℃ for 1 hour, hot rolling is performed. The total deformation is 40%. The deformation of each hot rolling pass is controlled at 5% to 10%. The sample is held for 15 minutes between each hot rolling pass. The final sample thickness is 28 mm.

[0081] (4) Solution treatment: The Cu-Ni-Co-Si alloy was placed in a box-type heat treatment furnace protected by high-purity argon gas and held at 960℃ for 2 hours. After the sample was taken out, it was quickly placed in cold water for quenching.

[0082] (5) Cold rolling in one step: After milling off the oxide film defects on the surface of the solid solution sample with a milling machine, the alloy thickness is processed to 25 mm, and then cold rolling is performed. The thickness after rolling is 12.5 mm and the deformation is 50%.

[0083] (6) Intermediate aging: tubular furnace aging, the specific process is aging at 500℃ for 1 hour;

[0084] (7) Secondary cold rolling: The thickness after cold rolling is 6.25 mm, and the deformation is 50%.

[0085] (8) Secondary intermediate aging: tubular furnace aging, the specific process is aging at 450℃ for 1 hour;

[0086] (9) Three-stage cold rolling: The thickness after cold rolling is 2.5 mm, and the deformation is 60%;

[0087] (10) Final aging: tube furnace aging, the specific process is aging at 400℃ for 1 to 20 hours to prepare Cu-Ni-Co-Si alloy plates and strips.

[0088] The Cu-Ni-Co-Si alloy sheet and strip of Comparative Example 1 were tested. The test methods and results are as follows:

[0089] High-temperature tensile testing: During the high-temperature tensile tests at 300, 400, and 500℃, thermocouples were used to precisely control the temperature, with the temperature error controlled within 5℃. A contact extensometer was used, and the tensile specimen dimensions and tensile parameters were consistent with those of the room-temperature tensile test. After the sample was placed in the thermocouple and kept at that temperature for 10 minutes, the test began, and the tensile test was repeated 3 times at each temperature.

[0090] Compared to Example 1, Comparative Example 1 replaced Ti with Cr, increased the Co content, and decreased the Mg content, while the Ni and Si contents remained largely unchanged. The substitution of the dominant Ti element highlighted the role of the alloying elements. Room temperature tensile tests were performed on the alloy, and the results are as follows... Figure 3 As shown. According to Figure 3 The tensile curves show that the tensile strength is ≥900MPa and the elongation after fracture is ≥7%. The specific properties of the prepared alloy under different aging parameters are summarized in Table 2.

[0091] High-temperature tensile tests were performed on Cu-Ni-Co-Si alloys, and the results are as follows: Figure 4 As shown. According to Figure 4 The tensile curves show that the tensile strength at 300℃ is ≥570MPa and the elongation after fracture is ≥20%; the tensile strength at 400℃ is ≥490MPa and the elongation after fracture is ≥30%; and the tensile strength at 500℃ is ≥250MPa and the elongation after fracture is ≥30%. It can be seen that the high-temperature performance of the alloy decreases significantly after Ti is replaced by Cr alloying element.

[0092] Table 2 Summary of the properties of Cu-Ni-Co-Si alloys with different aging parameters compared to Example 1

[0093] Aging temperature (°C) Delivery time (h) Tensile strength (MPa) Electrical conductivity (%IACS) Elongation (%) 400 1 919.6 40.62 5.9 400 4 885.4 43.6 5.7

[0094] Compare with Example 2

[0095] This comparative example provides a Cu-Ni-Co-Si alloy with the specific composition of Cu-2.1Ni-0.8Co-0.74Si-0.22Cr-0.11Ti, and its preparation process is as follows:

[0096] (1) Melting: Electrolytic Cu (purity > 99.95%), electrolytic Ni (purity > 99.95%), and polycrystalline Si (purity > 99.99%) raw materials, prepared in proportion, are placed into a vacuum medium-frequency induction melting furnace. Co, Mg, and Ti elements are added by placing Cu-10Mg master alloy, Co granules (purity > 99.95%), and Cr granules (purity > 99.99%) into a charging funnel. After all raw materials have been placed, the furnace is evacuated to a vacuum of 5 × 10⁻⁶. -3 Pa ~ 7 × 10 -3Pa, and backflushing argon gas as a protective gas, the specific pressure at this time is 0.05 Pa. Then the power is changed to 15 kW to raise the furnace body temperature to 1250-1300℃, and it is held for 5-10 min. After the Cu-Ni-Si in the crucible is completely melted, Cr particles and Co particles are added to the molten metal in sequence and held for 5-10 min. Then the power is adjusted to 10 kW to lower the temperature to 1200℃, and then Cu-Mg master alloy is added and held for 3 min. Finally, the power is adjusted to 5 kW to lower the temperature to 1100-1150℃, and then the liquid Cu-Ni-Co-Si alloy is poured into a preheated steel mold.

[0097] (2) Homogenization treatment: After removing the riser from the cast Cu-Ni-Co-Si alloy, place it in an argon-protected box-type heat treatment furnace, heat it to 900°C and hold it for 6 hours, and then cool it to room temperature.

[0098] (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the homogenized sample surface are removed by milling machine. After holding at 850℃ for 1 hour, hot rolling is performed. The total deformation is 40%. The deformation of each hot rolling pass is controlled at 5% to 10%. The sample is held for 15 minutes between each hot rolling pass. The final sample thickness is 28 mm.

[0099] (4) Solution treatment: The Cu-Ni-Co-Si alloy was placed in a box-type heat treatment furnace protected by high-purity argon gas and held at 960℃ for 2 hours. After the sample was taken out, it was quickly placed in cold water for quenching.

[0100] (5) Cold rolling in one step: After milling off the oxide film defects on the surface of the solid solution sample with a milling machine, the alloy thickness is processed to 25 mm, and then cold rolling is performed. The thickness after rolling is 12.5 mm and the deformation is 50%.

[0101] (6) Intermediate aging: tubular furnace aging, the specific process is aging at 500℃ for 1 hour;

[0102] (7) Secondary cold rolling: The thickness after cold rolling is 6.25 mm, and the deformation is 50%.

[0103] (8) Secondary intermediate aging: tubular furnace aging, the specific process is aging at 450℃ for 1 hour;

[0104] (9) Three-stage cold rolling: The thickness after cold rolling is 2.5 mm, and the deformation is 60%;

[0105] (10) Final aging: tube furnace aging, the specific process is aging at 400℃ for 1 to 20 hours to prepare Cu-Ni-Co-Si alloy plates and strips.

[0106] The Cu-Ni-Co-Si alloy sheet and strip of Comparative Example 2 were tested. The test methods and results are as follows:

[0107] High-temperature tensile testing: During the high-temperature tensile tests at 300, 400, and 500℃, thermocouples were used to precisely control the temperature, with the temperature error controlled within 5℃. A contact extensometer was used, and the tensile specimen dimensions and tensile parameters were consistent with those of the room-temperature tensile test. After the sample was placed in the thermocouple and kept at that temperature for 10 minutes, the test began, and the tensile test was repeated 3 times at each temperature.

[0108] Compared to Example 1, Comparative Example 2 replaced Mg with Cr, while the Ni and Si contents remained largely unchanged. The substitution of the dominant Mg element highlighted the role of the alloying elements. Room temperature tensile tests were performed on the alloy, and the results are as follows... Figure 6 As shown. According to Figure 6 The tensile curves show that the tensile strength is ≥800MPa and the elongation after fracture is ≥12%. After long-term aging, the strength decreases while the electrical conductivity increases further. The specific properties of the prepared alloy under different aging parameters are summarized in Table 3.

[0109] High-temperature tensile tests were performed on Cu-Ni-Co-Si alloys, and the results are as follows: Figure 7 As shown. According to Figure 7 The tensile curves show that the tensile strength at 300℃ is ≥570MPa and the elongation after fracture is ≥20%; the tensile strength at 400℃ is ≥450MPa and the elongation after fracture is ≥20%; and the tensile strength at 500℃ is ≥250MPa and the elongation after fracture is ≥20%. It can be seen that after Mg is replaced by Cr alloying element, the high-temperature performance of the alloy also decreases significantly.

[0110] Table 3 Summary of the properties of Cu-Ni-Co-Si alloys in Comparative Example 2 under different aging parameters

[0111] Aging temperature (°C) Delivery time (h) Tensile strength (MPa) Electrical conductivity (%IACS) Elongation (%) 400 1 820.13 49.99 13.6 400 16 698.2 57.3 15.3

[0112] Compare with Example 3

[0113] This comparative example provides a Cu-Ni-Co-Si alloy with the specific composition of Cu-2.1Ni-0.8Co-0.74Si-0.22Mg-0.11Ti, and its preparation process is as follows:

[0114] (1) Melting: Electrolytic Cu (purity > 99.95%), electrolytic Ni (purity > 99.95%), and polycrystalline Si (purity > 99.99%) raw materials, prepared in proportion, are placed into a vacuum medium-frequency induction melting furnace. Co, Mg, and Ti elements are added by placing Cu-10Mg master alloy, Co granules (purity > 99.95%), and Ti granules (purity > 99.99%) into a charging funnel. After all raw materials have been placed, the furnace is evacuated to a vacuum of 5 × 10⁻⁶. -3 Pa ~ 7 × 10 -3Pa, and backflushing argon gas as a protective gas, the specific gas pressure at this time is 0.05 Pa. Then the power is changed to 15 kW to raise the furnace body temperature to 1250-1300℃, and it is held for 5-10 min. After the Cu-Ni-Si in the crucible is completely melted, Ti particles and Co particles are added to the molten metal in sequence and held for 5-10 min. Then the power is adjusted to 10 kW to lower the temperature to 1200℃, and then Cu-Mg master alloy is added and held for 3 min. Finally, the power is adjusted to 5 kW to lower the temperature to 1100-1150℃, and then the liquid Cu-Ni-Co-Si alloy is poured into a preheated steel mold.

[0115] (2) Homogenization treatment: After removing the riser from the cast Cu-Ni-Co-Si alloy, place it in an argon-protected box-type heat treatment furnace, heat it to 900°C and hold it for 6 hours, and then cool it to room temperature.

[0116] (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the homogenized sample surface are removed by milling machine. After holding at 850℃ for 1 hour, hot rolling is performed. The total deformation is 40%. The deformation of each hot rolling pass is controlled at 5% to 10%. The sample is held for 15 minutes between each hot rolling pass. The final sample thickness is 28 mm.

[0117] (4) Solution treatment: The Cu-Ni-Co-Si alloy was placed in a box-type heat treatment furnace protected by high-purity argon gas and held at 960℃ for 2 hours. After the sample was taken out, it was quickly placed in cold water for quenching.

[0118] (5) Cold rolling in one step: After milling off the oxide film defects on the surface of the solid solution sample with a milling machine, the alloy thickness is processed to 25mm, and then cold rolling is performed. The thickness after rolling is 2.5mm and the deformation is 90%.

[0119] (6) Final aging: tube furnace aging, the specific process is aging at 400℃ for 1 to 20 hours to prepare Cu-Ni-Co-Si alloy plates and strips.

[0120] The Cu-Ni-Co-Si alloy sheet and strip of Comparative Example 2 were tested. The test methods and results are as follows:

[0121] High-temperature tensile testing: During the high-temperature tensile tests at 300, 400, and 500℃, thermocouples were used to precisely control the temperature, with the temperature error controlled within 5℃. A contact extensometer was used, and the tensile specimen dimensions and tensile parameters were consistent with those of the room-temperature tensile test. After the sample was placed in the thermocouple and kept at that temperature for 10 minutes, the test began, and the tensile test was repeated 3 times at each temperature.

[0122] Compared to Example 1, the process in Comparative Example 3 was modified to emphasize the role of multi-step rolling. Room temperature tensile tests were performed on the alloy, and the results are as follows: Figure 8 As shown. According to Figure 9 The tensile curves show a tensile strength ≥850MPa and an elongation after fracture ≥7%. The alloy prepared by one-step rolling has a low electrical conductivity, not exceeding 40% IACS. The specific properties of the prepared alloy under different aging parameters are summarized in Table 4.

[0123] High-temperature tensile tests were performed on Cu-Ni-Co-Si alloys, and the results are as follows: Figure 9 As shown. According to Figure 9 The tensile curves show that the tensile strength at 300℃ is ≥750MPa and the elongation after fracture is ≥20%; the tensile strength at 400℃ is ≥490MPa and the elongation after fracture is ≥20%; and the tensile strength at 300℃ is ≥300MPa and the elongation after fracture is ≥20%.

[0124] It is evident that the room temperature strength of the one-step rolled alloy can still reach 850 MPa, while maintaining high plasticity, thanks to the large deformation and aging of the alloy. However, the one-step rolling-aging process cannot guarantee the complete precipitation of precipitates in the alloy. Incomplete precipitation of solid solution elements increases the scattering effect on electrons, resulting in low electrical conductivity of the alloy (always less than 40% IACS). In contrast, the multi-step rolling-aging process utilizes intermediate aging to promote precipitation of the alloy during rolling and final aging processes, thus optimizing the alloy's electrical conductivity.

[0125] Table 4. Summary of the performance of Cu-Ni-Co-Si alloys of Comparative Example 3 under different aging parameters.

[0126] Aging temperature (°C) Delivery time (h) Tensile strength (MPa) Electrical conductivity (%IACS) Elongation (%) 400 1 848.0 29.23 8.1 400 4 857.8 33.14 10.3 400 8 876.0 34.95 9.4 400 16 872.8 38.07 7.0

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature, high-performance Cu-Ni-Co-Si alloy, comprising the following components: Ni content of 1.80wt% to 3.00wt%, Co content of 0.50wt% to 1.50wt%, Si content of 0.40wt% to 1.00wt%, Mg content of 0.05wt% to 0.4wt%, Ti content of 0.05wt% to 0.40wt%, with the balance being Cu and unavoidable impurities.

2. A method for preparing the high-temperature high-performance Cu-Ni-Co-Si alloy as described in claim 1, characterized in that, Specifically, the following steps are included: (1) Melting: Electrolytic Cu, electrolytic Ni and polycrystalline Si raw materials are put into the melting furnace in proportion. After the furnace body is evacuated, argon gas is backflushed as a protective gas. The temperature is raised to 1250-1300℃ and held for 5-10 minutes. After Cu-Ni-Si is completely melted, Ti particles and Co particles are added in sequence and held for 5-10 minutes. The temperature is lowered to 1200-1250℃ and Cu-Mg master alloy is added and held for 3-5 minutes. Finally, the temperature is lowered to 1100-1150℃ and poured into a preheated steel mold. (2) Homogenization treatment: After casting, the riser of the alloy is removed and placed in an argon-protected box heat treatment furnace. It is heated to 900-950℃ and held for 6-12 hours, and then cooled to room temperature in the furnace. (3) Hot rolling: Before hot rolling, the oxide film and inclusions on the alloy surface are milled off, and hot rolling is carried out after holding at 800-850℃ for 1-2 hours. (4) Solution treatment: The alloy is placed in a box-type heat treatment furnace protected by high-purity argon gas, held at 960-980℃ for 1-2 hours, and then taken out and quickly quenched in cold water. (5) One-time cold rolling: After milling away the oxide film defects on the surface of the solid solution sample, the alloy is subjected to one-time cold rolling; (6) Intermediate aging: An intermediate aging process is carried out in a tubular furnace, with the aging process being held at 450-550℃ for 1-2 hours. (7) Secondary cold rolling; (8) Secondary intermediate aging: Secondary intermediate aging is carried out in a tube furnace. The aging process is to hold at 400-500℃ for 1-2 hours. (9) Three-stage cold rolling; (10) Final aging: Final aging is carried out in a tube furnace at 350-450℃ for 1-20 hours to prepare high-temperature high-performance Cu-Ni-Co-Si alloy.

3. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The purity of electrolytic Cu in step (1) is >99.95%, the purity of electrolytic Ni is >99.95%, the purity of polycrystalline Si is >99.99%, the purity of Co particles is >99.95%, and the purity of Ti particles is >99.99%. And / or, the Cu-Mg master alloy in step (1) is a Cu-10Mg master alloy; And / or, in step (1), Cu-Mg master alloy, Co particles, and Ti particles are added through a feeding funnel.

4. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The preheating temperature of the preheated steel mold in step (1) is 200-300℃.

5. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The melting furnace mentioned in step (1) is a vacuum medium-frequency induction melting furnace with a vacuum degree of 5.5-7×10⁻⁶. -2 Pa, with a power of 5 to 15 kW.

6. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The total deformation of hot rolling in step (3) is 30-40%, and the deformation per pass is controlled at 5%-10%; the final rolling thickness is 28-32 mm, the deformation per pass is 2-3 mm, and the heat preservation time between each rolling pass is 15-20 min.

7. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, Step (5) describes a single cold rolling process: after the alloy is processed to a thickness of 25-30 mm, it is cold rolled to a thickness of 11-13 mm and a deformation of 40-60%.

8. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The secondary cold rolling in step (7) results in a thickness of 5-7 mm and a deformation of 40-60%.

9. The method for preparing high-temperature high-performance Cu-Ni-Co-Si alloys according to claim 2, characterized in that, The three cold rolling processes described in step (9) result in a thickness of 2-3 mm and a deformation of 40-60%.

10. The application of the high-temperature high-performance Cu-Ni-Co-Si alloy of claim 1 in the fields of automotive connectors, high-speed railway contact networks, or aerospace electronic components.

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