High-strength high-conductivity Cu-Ag alloy and preparation method thereof

Abstract

The invention belongs to the field of alloy materials, and discloses a high-strength and high-conductivity Cu-Ag alloy which comprises the following components in percentage by weight: 10-20% of Ag, 0.01-0.3% of Cr, 0.01-0.3% of Zr, 0.01-0.3% of V, 0.01-0.3% of Re and the balance of copper and inevitable impurities. The invention further discloses a preparation method of the high-strength and high-conductivity Cu-Ag alloy, and the preparation method comprises the following steps: melting raw materials, then carrying out downward drawing and drawing to obtain a Cu-Ag alloy wire, then sequentially carrying out pre-cold drawing, solution treatment and aging treatment on the Cu-Ag alloy wire, and then alternately carrying out cold drawing treatment and annealing treatment for several times to obtain the high-strength and high-conductivity Cu-Ag alloy. The high-strength and high-conductivity Cu-Ag alloy wire is excellent in mechanical property and conductivity, the service life of the material under extreme conditions can be prolonged, the conductivity of the high-strength and high-conductivity Cu-Ag alloy wire is not lower than 75% IACS, the ultimate tensile strength is not lower than 1050 MPa, and the high-temperature softening resistance temperature is not lower than 341 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials, and particularly relates to a high-strength, high-conductivity Cu-Ag alloy and its preparation method. Background Technology

[0002] High-strength, high-conductivity copper alloy wires are widely used in high-field magnet wires, rail transit contact wires, catenary wires, high-end connectors, lead frames, motor coils, pulse power, and electromagnetic emission. These applications require materials with high conductivity to reduce Joule heating and high tensile strength to resist Lorentz forces. Commonly used high-strength, high-conductivity copper alloys in existing engineering applications include Cu-Cr alloys (tensile strength ≥350 MPa, conductivity ≥80% IACS), Cu-Cr-Zr alloys (tensile strength ≥500 MPa, conductivity ≥75% IACS), and Cu-Ni-Si alloys (tensile strength ≥800 MPa, conductivity ≥40% IACS). However, with continuous technological advancements and consideration of material stability under extreme conditions, higher requirements are placed on the strength and conductivity of copper alloy wires, necessitating the development of new high-strength, high-conductivity copper alloys.

[0003] As a typical material combining high strength and high conductivity, Cu-Ag alloy wires achieve ultra-high strength under high conductivity conditions by relying on the silver fiber structure resulting from phase separation and strong deformation. Through casting and extrusion to obtain a supersaturated solid solution, followed by large deformation cold drawing and low-temperature aging, the Ag phase forms axially oriented nanoscale filaments or layered structures in the Cu matrix, achieving interface strengthening for load transfer. This not only improves the strength of the alloy wire but also significantly enhances its conductivity along the drawing direction. However, traditional Cu-Ag alloys have poor thermal stability; alloy wires prepared by large deformation cold drawing experience significant performance degradation at 200-300 °C, making it difficult to guarantee normal application of the alloy wires in extreme high-temperature environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a high-strength, high-conductivity Cu-Ag alloy and its preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A high-strength, high-conductivity Cu-Ag alloy, comprising the following components by weight percentage: Ag 10-20%, Cr 0.01-0.3%, Zr 0.01-0.3%, V 0.01-0.3%, Re 0.01-0.3%, with the balance being copper and unavoidable impurities; Re is at least one of La, Ce, Sc and Y.

[0006] Adding Ag to the alloy transforms it from a supersaturated solid solution into nanoscale fine precipitates oriented along the wire axis during the large deformation drawing-solution treatment-low temperature aging process. This achieves load transfer and precipitation strengthening, while the continuous Cu matrix provides the main conductive channels, resulting in high strength at high conductivity. Cr can precipitate as a phase after aging, providing precipitation strengthening. Zr pins grain boundaries, inhibiting grain growth and dislocation movement, thus improving alloy strength. V provides a small amount of solid solution strengthening and precipitation strengthening. Ce and La purify the microstructure, improve the alloy's conductivity, and form rare earth compounds at grain boundaries, hindering grain migration. Sc forms nanoscale ordered precipitates, providing significant precipitation strengthening and significantly improving the alloy's resistance to high-temperature softening. Y not only purifies grains and improves conductivity but also forms oxides, enhancing the alloy's resistance to high-temperature softening.

[0007] In this application, if the amount of Ag added is high (>20%), the cost of preparing alloy wire is too high. If the amount of Ag added is low (<10%), the fiber reinforcement effect provided by Ag is not significant, affecting the mechanical properties of the alloy. If the content of elements such as Cr, Zr, V, and Re is high, submicron or even micron-sized Cr, Zr, V, and Re particles are easily generated in the Cu matrix, reducing the mechanical properties of the alloy.

[0008] In the aforementioned high-strength, high-conductivity Cu-Ag alloy, preferably, the total weight percentage of Cr, Zr, V, and Re elements is 0.1-0.7%.

[0009] Preferably, the high-strength, high-conductivity Cu-Ag alloy has a conductivity of not less than 75% IACS, an ultimate tensile strength of not less than 1050 MPa, and a high-temperature softening temperature of not less than 341 ℃.

[0010] As a general inventive concept, the present invention also provides a method for preparing the high-strength, high-conductivity Cu-Ag alloy as described above, comprising the following steps: (1) Pure copper and pure silver are loaded into a continuous casting furnace. After the furnace cavity is evacuated, an inert protective gas is introduced. The temperature is raised to the point where the pure copper and pure silver melt. Then, an intermediate alloy is added. The furnace is then held at the temperature and then drawn into a billet to obtain Cu-Ag alloy wire. The intermediate alloy includes copper-chromium alloy, copper-zirconium alloy, copper-vanadium alloy and Re-containing alloy. The Re-containing intermediate alloy includes at least one of copper-lanthanum alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium intermediate alloy. (2) The Cu-Ag alloy wire is subjected to pre-cold drawing, solution treatment and aging treatment in sequence, and then cold drawing and annealing treatment are performed alternately several times to obtain the high-strength and high-conductivity Cu-Ag alloy.

[0011] In the above preparation method, preferably, in step (1), the inert protective gas is nitrogen, the melting temperature is 1200-1500 ℃, the holding temperature is 1200-1300 ℃, and the holding time is 15-20 min.

[0012] In the preferred embodiment of the above preparation method, in step (2), the total strain of the pre-cold drawing is 2.0-2.5, the strain per drawing pass is 0.10-0.30, and the drawing speed is 5-10 mm / s. The purpose of the pre-cold drawing is to eliminate casting defects caused by continuous casting, including porosity and cracks, and to break up the coarse as-cast structure, providing a grain refinement effect. When the total strain is below the range controlled by this invention, defects in the alloy are not easily eliminated; when the total strain is above the range controlled by this invention, the diameter of the wire is too small, resulting in insufficient total strain in subsequent drawing, and the strengthening effect provided is limited.

[0013] In the preferred embodiment of the above preparation method, in step (2), the solution treatment temperature is 650 ℃-750 ℃, the solution holding time is 4-8 h, and the wire is water-cooled after the solution treatment. The solution treatment makes the microstructure and composition of the alloy more uniform, eliminates work hardening, and provides uniform precipitation sites for subsequent aging. During the solution treatment process, if the solution treatment temperature is too high (>750 ℃), the Ag-rich phase and Cu-Ag eutectic structure inside the alloy will melt. If the solution treatment temperature is too low (<650 ℃), elements such as Cr, Zr, Ce, La, V, and Re cannot dissolve into the Cu matrix, which will damage the conductivity of the alloy and will not provide aging precipitation strengthening effect in the subsequent process.

[0014] The aging treatment temperature is 300℃-500℃, and the holding time is 1-8 hours. After aging treatment, the wire is water-cooled. The purpose of aging treatment is to precipitate nano-sized particles, improve the hardness and strength of the alloy, and increase its conductivity. When the aging temperature or time is higher than the above range, the precipitated phase tends to coarsen, leading to a decrease in strength and resistance to high-temperature softening. When the aging temperature or time is lower than the above range, precipitation is insufficient, the strengthening is not significant, and there are more solute atoms remaining in the matrix, which limits the conductivity.

[0015] In the above preparation method, preferably, in step (2), several cold drawing and annealing processes are performed alternately, including a first cold drawing process, a first annealing process, a second cold drawing process, a second annealing process, a third cold drawing process, a third annealing process, and a fourth cold drawing process.

[0016] In the above-mentioned preparation method, preferably, the total strain of the Cu-Ag alloy wire in the first cold drawing treatment is 4.0-5.0, the strain per pass is 0.10-0.30, and the drawing speed is 10-15 mm / s. The first cold drawing treatment introduces an appropriate amount of dislocations and substructures and breaks the continuous enriched structure. On the other hand, it provides uniform nucleation conditions for the subsequent first annealing.

[0017] The total strain of the Cu-Ag alloy wire after the second cold drawing treatment is 5.0-5.5 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 8-10 mm / s. The second cold drawing treatment further improves the strength and stabilizes the dimensions. On the other hand, it accumulates appropriate distortion energy to provide sufficient power for the precipitates in the subsequent second annealing process, thereby improving the strength and conductivity of the alloy.

[0018] The total strain of the Cu-Ag alloy wire after the third cold drawing treatment is 5.5-6.5, the strain per pass is 0.10-0.30, and the drawing speed is 5-8 mm / s. The effect of the third cold drawing treatment is to introduce dislocation substructure after the second annealing, which further refines the Ag fibers.

[0019] The total strain of the Cu-Ag alloy wire after the fourth cold drawing treatment is 6.5-7.0 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 3-5 mm / s. The purpose of the fourth cold drawing treatment is to further refine the grain size and Ag fiber size, thereby improving the strength of the alloy, based on the third cold drawing treatment and the third annealing treatment.

[0020] In the preferred preparation method described above, the temperature for both the first and second annealing treatments is 350℃-400℃, and the holding time for both treatments is 30-60 min. The purpose of the first and second annealing treatments is to further precipitate second-phase particles, improve the hardness and strength of the alloy, and increase its conductivity. When the temperature and time of the first and second annealing treatments are higher than the range required by this invention, the work hardening effect provided by cold drawing disappears too quickly, the alloy softens easily, and its hardness and strength are low. When the temperature and time of the first and second annealing treatments are lower than the range required by this invention, the second-phase particles cannot precipitate further, resulting in some solute atoms remaining in the matrix and reducing the conductivity of the alloy.

[0021] The third annealing treatment is performed at a temperature of 300℃-350℃, with a holding time of 10-30 minutes. After three cold drawing processes, the alloy has a high dislocation density and strong resistance to deformation. The third annealing treatment can further enhance the alloy's deformation capacity, facilitating the smooth progress of the fourth cold drawing. When the temperature and time of the third annealing treatment exceed the range required by this invention, the work hardening effect produced by cold drawing decreases rapidly, Ag fibers tend to coarsen, and the mechanical properties of the alloy are reduced. When the temperature and time of the third annealing treatment are below the range required by this invention, the alloy's resistance to deformation is difficult to eliminate, and wire breakage is likely to occur during the fourth cold drawing process.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the copper alloy of the present invention, a microalloying design is adopted with Ag as the main component and Cr, Zr, V, Re and other elements as auxiliary components: Ag forms nanoscale Ag precipitates during solid solution-aging process, which are semi-coherent with Cu matrix and provide significant precipitation strengthening; at the same time, supersaturated solute atoms are precipitated from the matrix, reducing electron scattering and improving conductivity; Cr, Zr, V, Re and other elements form fine and dispersed Cr, Zr and other precipitates, V, Sc, La compounds and Ce, Y oxides during aging-deformation, which produce pinning effect, hinder dislocation movement, and inhibit grain boundary migration, thereby increasing the alloy's high temperature softening temperature and removing internal impurities, thus improving the alloy's conductivity. Meanwhile, the added Cr, Zr, V, Re and Ag elements, as well as their interactions, can promote precipitation and inhibit growth, further enhancing the precipitation strengthening effect and purifying the matrix. The synergistic effect of Ag with Cr, Zr, V, Re and other elements enables the alloy wire of this invention to achieve high strength and thermal stability while maintaining high conductivity.

[0023] (2) The preparation process of this invention adopts a synergistic process of continuous casting-prepared cold drawing-solution treatment-aging-stage cold drawing and annealing to prepare a Cu-Ag alloy with high thermal stability, high strength and high conductivity: Prepared cold drawing breaks up the coarse as-cast structure and enriches Ag; solution treatment achieves homogenization of the structure and forms a supersaturated solid solution; aging promotes the precipitation of fine and dispersed Ag phases, which, together with nano-sized precipitates of Cr, Zr, V, Re and other elements, form synergistic precipitation strengthening; after multi-stage cold drawing and staged annealing, fine and uniform grains and stable fibrous structure are obtained. The above processes work together to significantly improve the strength of the alloy while ensuring high conductivity. The anti-softening effect of each element Cr, Zr, V, Re and other elements, together with the pinning effect of precipitates, synergistically improve the thermal stability of the alloy, thereby obtaining a high-strength and high-conductivity Cu-Ag alloy.

[0024] (3) The high-strength, high-conductivity Cu-Ag alloy wire of the present invention has excellent mechanical and electrical properties, which can extend the service life of the material under extreme conditions: its conductivity is not less than 75% IACS, its ultimate tensile strength is not less than 1050 MPa, and its high-temperature softening temperature is not less than 341 ℃.

[0025] (4) The preparation method of the present invention uses continuous casting to prepare dense rod blanks. The process is simple and low-cost. It can prepare long-size and multi-specification wires, with a wide range of applications and is convenient for large-scale industrial production. Attached Figure Description

[0026] 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.

[0027] Figure 1 These are EBSD images of the longitudinal section of the alloy wire obtained after aging treatment during the preparation of the high-strength, high-conductivity Cu-Ag alloy in Example 5 of this invention. Figure 2 This is a SEM image of the tensile fracture surface of the high-strength, high-conductivity Cu-Ag alloy wire prepared in Example 5 of this invention. Detailed Implementation

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Example 1: A high-strength, high-conductivity Cu-Ag alloy of the present invention comprises, by weight percentage: Ag 10%, Cr 0.3%, Zr 0.3%, V 0.01%, Ce 0.01%, La 0.02%, Y 0.02%, Sc 0.01%, with the balance being copper and unavoidable impurities.

[0032] The preparation method of the high-strength, high-conductivity Cu-Ag alloy in this embodiment includes the following steps: (1) The materials are prepared according to the mass percentages of Ag 10%, Cr 0.3%, Zr 0.3%, V 0.01%, Ce 0.01%, La 0.02%, Y 0.02%, Sc 0.01% and the balance of copper. Pure copper and pure silver are loaded into the continuous casting furnace. After the furnace cavity is evacuated, nitrogen is introduced and the temperature is raised to 1200 ℃ to melt the copper and silver. Then, copper-chromium alloy, copper-zirconium alloy, copper-lanthanum alloy, copper-vanadium alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium master alloy are added. The temperature is held at 1200 ℃ for 20 min. Finally, the billet is drawn downward to obtain rod-shaped Cu-Ag alloy wire.

[0033] (2) The rod-shaped Cu-Ag alloy wire obtained after step (1) is subjected to pre-cold drawing treatment, wherein the total strain of pre-cold drawing is 2.0, the strain of each drawing is controlled at 0.10, and the drawing speed is controlled at 10 mm / s.

[0034] (3) The wire treated in step (2) is subjected to solution treatment at a temperature of 650 ℃ and a heat preservation time of 8 h. Then the wire is water-cooled.

[0035] (4) The solid solution sample obtained after step (3) is subjected to aging treatment at a temperature of 300 °C and an aging holding time of 8 h. Then the sample is water-cooled.

[0036] (5) The sample obtained after step (4) is subjected to the first cold drawing treatment so that the total strain of Cu-Ag alloy wire reaches 4.0, the strain of each pass is 0.10, and the drawing speed is controlled at 15 mm / s; then the cold-drawn sample is subjected to the first annealing treatment. The first annealing treatment temperature is 350 ℃ and the first annealing treatment time is 60 min.

[0037] (6) The annealed sample obtained after step (5) is subjected to a second cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.0, the strain of each pass is 0.10, and the drawing speed is controlled at 10 mm / s; then a second annealing treatment is performed at a temperature of 350 ℃ and a time of 60 min.

[0038] (7) The annealed sample obtained after step (6) is subjected to a third cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.5, the strain of each pass is 0.10, and the drawing speed is controlled at 8 mm / s; then a third annealing treatment is performed at a temperature of 300 ℃ and a holding time of 30 min.

[0039] (8) The annealed sample obtained after step (7) is subjected to a fourth cold drawing process to make the total strain of Cu-Ag alloy wire reach 6.5, the strain of each pass is 0.10, and the drawing speed is controlled at 5 mm / s to obtain high-strength and high-conductivity Cu-Ag alloy wire.

[0040] Example 2: A high-strength, high-conductivity Cu-Ag alloy of the present invention comprises, by weight percentage: 15% Ag, 0.02% Cr, 0.02% Zr, 0.3% V, 0.3% Ce, 0.01% La, 0.01% Y, 0.02% Sc, with the balance being copper and unavoidable impurities.

[0041] The preparation method of the high-strength, high-conductivity Cu-Ag alloy in this embodiment includes the following steps: (1) The materials are prepared according to the mass percentages of Ag 15%, Cr 0.02%, Zr 0.02%, V 0.3%, Ce 0.3%, La 0.01%, Y 0.01%, Sc 0.02% and the balance of copper. Pure copper and pure silver are loaded into the continuous casting furnace. After the furnace cavity is evacuated, nitrogen is introduced and the temperature is raised to 1500 ℃ to melt the copper and silver. Then, copper-chromium alloy, copper-zirconium alloy, copper-lanthanum alloy, copper-vanadium alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium master alloy are added. The temperature is held at 1300 ℃ for 15 min. Finally, the billet is drawn downward to obtain rod-shaped Cu-Ag alloy wire.

[0042] (2) The rod-shaped Cu-Ag alloy wire obtained after step (1) is subjected to pre-cold drawing treatment, wherein the total strain of pre-cold drawing is 2.5, the strain of each drawing is controlled at 0.30, and the drawing speed is controlled at 5 mm / s.

[0043] (3) The wire treated in step (2) is subjected to solution treatment at a temperature of 750 ℃ ​​and a heat preservation time of 4 h. Then the wire is cooled by water.

[0044] (4) The solid solution sample obtained after step (3) is subjected to aging treatment at a temperature of 500 ℃ and an aging holding time of 4 h. Then the sample is water-cooled.

[0045] (5) The sample obtained after step (4) is subjected to the first cold drawing treatment so that the total strain of Cu-Ag alloy wire reaches 5.0, the strain of each pass is 0.30, and the drawing speed is controlled at 10 mm / s; then the cold-drawn sample is subjected to the first annealing treatment. The first annealing treatment temperature is 400 ℃ and the first annealing treatment time is 30 min.

[0046] (6) The annealed sample obtained after step (5) is subjected to a second cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.5, the strain of each pass is 0.30, and the drawing speed is controlled at 8 mm / s; then a second annealing treatment is performed at a temperature of 400 ℃ and a time of 30 min.

[0047] (7) The annealed sample obtained after step (6) is subjected to a third cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 6.5, the strain of each pass is 0.30, and the drawing speed is controlled at 5 mm / s; then a third annealing treatment is performed at a temperature of 350 ℃ and a holding time of 10 min.

[0048] (8) The annealed sample obtained after step (7) is subjected to a fourth cold drawing process to make the total strain of Cu-Ag alloy wire reach 7.0, the strain of each pass is 0.30, and the drawing speed is controlled at 3 mm / s to obtain high-strength and high-conductivity Cu-Ag alloy wire.

[0049] Example 3: A high-strength, high-conductivity Cu-Ag alloy of the present invention comprises, by weight percentage: 10% Ag, 0.01% Cr, 0.01% Zr, 0.02% V, 0.02% Ce, 0.3% La, 0.3% Y, 0.02% Sc, with the balance being copper and unavoidable impurities.

[0050] The preparation method of the high-strength, high-conductivity Cu-Ag alloy in this embodiment includes the following steps: (1) The materials are prepared according to the mass percentages of Ag 10%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.3%, Y 0.3%, Sc 0.02% and the balance of copper. Pure copper and pure silver are loaded into the continuous casting furnace. After the furnace cavity is evacuated, nitrogen is introduced and the temperature is raised to 1500 ℃ to melt the copper and silver. Copper-chromium alloy, copper-zirconium alloy, copper-lanthanum alloy, copper-vanadium alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium master alloy are added. The temperature is held at 1250 ℃ for 20 min. Finally, the billet is drawn downward to obtain rod-shaped Cu-Ag alloy wire.

[0051] (2) The rod-shaped Cu-Ag alloy wire obtained after step (1) is subjected to pre-cold drawing treatment, wherein the total strain of pre-cold drawing is 2.5, the strain of each drawing pass is controlled at 0.25, and the drawing speed is controlled at 8 mm / s.

[0052] (3) The wire treated in step (2) is subjected to solution treatment at a temperature of 750 ℃ ​​and a heat preservation time of 6 h. Then the wire is water-cooled.

[0053] (4) The solid solution sample obtained after step (3) is subjected to aging treatment at a temperature of 500 ℃ and an aging holding time of 3 h. Then the sample is water-cooled.

[0054] (5) The sample obtained after step (4) is subjected to the first cold drawing treatment so that the total strain of Cu-Ag alloy wire reaches 4.5, the strain of each pass is 0.20, and the drawing speed is controlled at 12 mm / s; then the cold-drawn sample is subjected to the first annealing treatment. The first annealing treatment temperature is 400 ℃ and the first annealing treatment time is 50 min.

[0055] (6) The annealed sample obtained after step (5) is subjected to a second cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.3, the strain of each pass is 0.20, and the drawing speed is controlled at 9 mm / s; then a second annealing treatment is performed at a temperature of 400 ℃ and a time of 40 min.

[0056] (7) The annealed sample obtained after step (6) is subjected to a third cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 6.0, the strain of each pass is 0.20, and the drawing speed is controlled at 6 mm / s; then a third annealing treatment is performed at a temperature of 350 ℃ and a holding time of 15 min.

[0057] (8) The annealed sample obtained after step (7) is subjected to a fourth cold drawing process to make the total strain of Cu-Ag alloy wire reach 6.8, the strain of each pass is 0.20, and the drawing speed is controlled at 4 mm / s to obtain high-strength and high-conductivity Cu-Ag alloy wire.

[0058] Example 4: A high-strength, high-conductivity Cu-Ag alloy of the present invention comprises, by weight percentage: 20% Ag, 0.02% Cr, 0.02% Zr, 0.02% V, 0.02% Ce, 0.02% La, 0.02% Y, 0.3% Sc, with the balance being copper and unavoidable impurities.

[0059] The preparation method of the high-strength, high-conductivity Cu-Ag alloy in this embodiment includes the following steps: (1) The materials are prepared according to the mass percentages of Ag 20%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.3%, Y 0.3%, Sc 0.3% and the balance of copper. Pure copper and pure silver are loaded into the continuous casting furnace. After the furnace cavity is evacuated, nitrogen is introduced and the temperature is raised to 1300 ℃ to melt the copper and silver. Copper-chromium alloy, copper-zirconium alloy, copper-lanthanum alloy, copper-vanadium alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium master alloy are added. The temperature is held at 1250 ℃ for 18 min. Finally, the billet is drawn downward to obtain rod-shaped Cu-Ag alloy wire.

[0060] (2) The rod-shaped Cu-Ag alloy wire obtained after step (1) is subjected to pre-cold drawing treatment, wherein the total strain of pre-cold drawing is 2.3, the strain of each drawing pass is controlled at 0.30, and the drawing speed is controlled at 8 mm / s.

[0061] (3) The wire processed in step (2) is subjected to solution treatment at a temperature of 750 ℃ ​​and a heat preservation time of 8 hours. Then the wire is water-cooled.

[0062] (4) The solid solution sample obtained after step (3) is subjected to aging treatment at a temperature of 500 ℃ and an aging holding time of 8 h. Then the sample is water-cooled.

[0063] (5) The sample obtained after step (4) is subjected to the first cold drawing treatment so that the total strain of Cu-Ag alloy wire reaches 4.0, the strain of each pass is 0.10, and the drawing speed is controlled at 10 mm / s; then the cold-drawn sample is subjected to the first annealing treatment. The first annealing treatment temperature is 350 ℃ and the first annealing treatment time is 30 min.

[0064] (6) The annealed sample obtained after step (5) is subjected to a second cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.0, the strain of each pass is 0.10, and the drawing speed is controlled at 8 mm / s; then a second annealing treatment is performed at a temperature of 350 ℃ and a time of 30 min.

[0065] (7) The annealed sample obtained after step (6) is subjected to a third cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.5, the strain of each pass is 0.10, and the drawing speed is controlled at 5 mm / s; then a third annealing treatment is performed at a temperature of 300 ℃ and a holding time of 10 min.

[0066] (8) The annealed sample obtained after step (7) is subjected to a fourth cold drawing process to make the total strain of Cu-Ag alloy wire reach 6.8, the strain of each pass is 0.10, and the drawing speed is controlled at 3 mm / s to obtain high-strength and high-conductivity Cu-Ag alloy wire.

[0067] Example 5: A high-strength, high-conductivity Cu-Ag alloy of the present invention comprises, by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0068] The preparation method of the high-strength, high-conductivity Cu-Ag alloy in this embodiment includes the following steps: (1) The materials are prepared according to the mass percentages of Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, Sc 0.02% and the balance of copper. Pure copper and pure silver are loaded into the continuous casting furnace. After the furnace cavity is evacuated, nitrogen is introduced and the temperature is raised to 1300 ℃ to melt the copper and silver. Copper-chromium alloy, copper-zirconium alloy, copper-lanthanum alloy, copper-vanadium alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium master alloy are added. The temperature is held at 1200 ℃ for 18 min. Finally, the billet is drawn downward to obtain rod-shaped Cu-Ag alloy wire.

[0069] (2) The rod-shaped Cu-Ag alloy wire obtained after step (1) is subjected to pre-cold drawing treatment, wherein the total strain of pre-cold drawing is 2.0, the strain of each drawing pass is controlled at 0.10, and the drawing speed is controlled at 10 mm / s.

[0070] (3) The wire processed in step (2) is subjected to solution treatment at a temperature of 700 ℃ and a heat preservation time of 4 h. Then the wire is water-cooled.

[0071] (4) The solution-treated sample obtained after step (3) is subjected to aging treatment at a temperature of 350 ℃ for 1 h. The sample is then water-cooled. The EBSD image of its longitudinal section is shown below. Figure 1 As shown.

[0072] (5) The sample obtained after step (4) is subjected to the first cold drawing treatment so that the total strain of Cu-Ag alloy wire reaches 4.0, the strain of each pass is 0.10, and the drawing speed is controlled at 10 mm / s; then the cold-drawn sample is subjected to the first annealing treatment. The first annealing treatment temperature is 400 ℃ and the first annealing treatment time is 30 min.

[0073] (6) The annealed sample obtained after step (5) is subjected to a second cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.0, the strain of each pass is 0.10, and the drawing speed is controlled at 10 mm / s; then a second annealing treatment is performed at a temperature of 350 ℃ and a time of 30 min.

[0074] (7) The annealed sample obtained after step (6) is subjected to a third cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 5.5, the strain of each pass is 0.10, and the drawing speed is controlled at 8 mm / s; then a third annealing treatment is performed, the temperature of the third annealing treatment is 300 ℃, and the holding time of the third annealing is 10 min.

[0075] (8) The annealed sample obtained after step (7) is subjected to a fourth cold drawing treatment to make the total strain of Cu-Ag alloy wire reach 7.0, the strain of each pass is 0.10, and the drawing speed is controlled at 5 mm / s to obtain high-strength and high-conductivity CuAg alloy wire. The SEM image of its tensile fracture surface is shown in the figure. Figure 2 As shown.

[0076] Comparative Example 1: The Cu-Ag alloy wire of this comparative example comprises, by weight percentage: Ag 5.0%, Cr 1.0%, Zr 1.0%, V 1.0%, Ce 1.0%, La 1.0%, Y 1.0%, Sc 1.0%, with the balance being copper and unavoidable impurities.

[0077] The Cu-Ag alloy wire 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.

[0078] Comparative Example 2: The Cu-Ag alloy wire of this comparative example has the same alloy composition as that of Example 2. The difference is that the solution treatment temperature in step (3) of the preparation method of this comparative example is 600 °C and the holding time is 2 h. Other process parameters are the same as those of Example 2.

[0079] Comparative Example 3: The Cu-Ag alloy wire of this comparative example has the same alloy composition as that of Example 3. The difference between the preparation method of the Cu-Ag alloy wire of this comparative example and that of Example 3 is that the solid solution sample obtained after step (3) is not subjected to aging treatment, but is directly subjected to four cold drawing treatments and three annealing treatments (process conditions are the same as in Example 3).

[0080] Comparative Example 4: The Cu-Ag alloy wire of this comparative example has the same alloy composition as that of Example 4. The difference between the preparation method of the Cu-Ag alloy wire of this comparative example and that of Example 4 is that in step (5), the first annealing temperature is 200 °C and the annealing time is 30 min. Other process parameters are the same as those of Example 4.

[0081] Comparative Example 5: The Cu-Ag alloy wire in this comparative example has the same alloy composition as that in Example 5. The difference between the preparation method of the Cu-Ag alloy wire in this comparative example and that in Example 5 is that the third annealing treatment and the fourth cold drawing treatment are not performed. The total strain during drawing is 5.5. Other process parameters are the same as those in Example 5.

[0082] Comparative Example 6: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0083] The only difference between the Cu-Ag alloy wire in this comparative example and Example 5 is the alloy composition; no Cr element was added. The preparation method is exactly the same as that in Example 5.

[0084] Comparative Example 7: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0085] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no Zr element was added, and the preparation method is exactly the same as that in Example 5.

[0086] Comparative Example 8: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0087] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no V element was added. The preparation method is exactly the same as that in Example 5.

[0088] Comparative Example 9: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, La 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0089] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no Ce element was added. The preparation method is exactly the same as that in Example 5.

[0090] Comparative Example 10: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, Y 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0091] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no La element was added. The preparation method is exactly the same as that in Example 5.

[0092] Comparative Example 11: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Sc 0.02%, with the balance being copper and unavoidable impurities.

[0093] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no Y element was added. The preparation method is exactly the same as that in Example 5.

[0094] Comparative Example 12: The Cu-Ag alloy wire of this comparative example comprises the following components by weight percentage: Ag 15%, Cr 0.02%, Zr 0.02%, V 0.02%, Ce 0.02%, La 0.02%, Y 0.02%, with the balance being copper and unavoidable impurities.

[0095] The only difference between the Cu-Ag alloy wire in this comparative example and that in Example 5 is the alloy composition; no Sc element was added. The preparation method is exactly the same as that in Example 5.

[0096] The Cu-Ag alloy wires prepared in the above embodiments and comparative examples were subjected to tensile tests, electrical conductivity tests, and softening temperature tests. Their ultimate tensile strength (GB / T 228.1) was also tested. 2021), conductivity (GB / T 32791) The results, such as the high temperature softening temperature (GB / T 33370-2016) and the high temperature softening temperature (GB / T 33370-2016), are shown in Table 1.

[0097] Table 1. Properties of Cu-Ag alloy wires prepared in each example and comparative example.

[0098] As shown in Table 1, the experimental results of Comparative Example 1 and Example 1 indicate that excessively low Ag content and excessively high Cr, Zr, V, and Re content lead to a decrease in the mechanical and electrical properties of the alloy. This is because excessively low Ag content provides insufficient fiber reinforcement, while excessively high Cr, Zr, V, and Re content causes Cr and V to easily form coarse particles, deteriorating the mechanical properties of the material. Excessive accumulation of Zr and Re at the interface leads to a decrease in the electrical conductivity of the alloy wire. If the Cr, Zr, V, and Re content is too low, it cannot provide significant precipitation strengthening and purification effects, nor can it promote Ag precipitation, resulting in a decrease in the mechanical properties and electrical conductivity of the alloy. The experimental results of Comparative Example 2 and Example 2 indicate that excessively low solution temperature and short holding time easily lead to a decrease in the alloy's performance. This is because Cr, Zr, V, and Re elements cannot be completely dissolved into the matrix, and therefore cannot produce significant precipitation strengthening effects during subsequent heat treatment. Excessively high solution temperature causes the eutectic structure inside the alloy to melt. The experimental results of Comparative Example 3 and Example 3 show that aging treatment followed by cold drawing and intermediate annealing after solution treatment can achieve higher conductivity, tensile strength, and high-temperature softening temperature. This is because aging treatment can precipitate a large number of fine precipitates, which can significantly increase the dislocation density of the alloy during deformation. The experimental results of Comparative Example 4 and Example 4 show that the first annealing temperature is too low, which prevents the residual solid solution atoms in the matrix from precipitating, reducing the conductivity and precipitation strengthening effect of the alloy. The experimental results of Comparative Example 5 and Example 5 show that the alloy wire obtained by only three cold drawing treatments and two intermediate annealing treatments has lower strength and relatively lower conductivity. This is because the greater the deformation, the smaller the fiber size inside the alloy, which hinders dislocation movement more. Furthermore, subsequent heat treatment can improve the conductivity of the alloy. The experimental results of Comparative Example 6 and Example 5 show that the absence of Cr will result in the loss of the partial precipitation strengthening effect provided by Cr, leading to a decrease in strength. Moreover, the nano-scale Cr precipitates formed during heat treatment can inhibit recrystallization and increase the high-temperature softening temperature of the alloy. The experimental results of Comparative Example 7 and Example 5 show that the addition of Zr can improve the strength and high-temperature softening temperature of the alloy. This is because the presence of Zr can inhibit grain boundary migration, and the formed compounds can improve the strength of the alloy. The experimental results of Comparative Example 8 and Example 5 show that the addition of V can promote Ag precipitation and provide additional precipitation strengthening effect. The experimental results of Comparative Example 9 and Example 5 show that Ce can form compounds, purify the interior of grains, reduce electron scattering, and improve the mechanical properties of the alloy. The experimental results of Comparative Example 10 and Example 5 show that the addition of La can purify the melt, reduce impurities such as O and S, and improve the conductivity and mechanical properties of the alloy. However, excessive addition of La will lead to coarse La precipitates, which will deteriorate the conductivity and mechanical properties.The experimental results of Comparative Example 11 and Example 5 show that the addition of Y can promote the formation of Y oxide inside the alloy and improve the conductivity of the alloy. The experimental results of Comparative Example 12 and Example 5 show that the addition of Sc can regulate the precipitation mode of Ag, promote continuous precipitation, increase the interface of Ag fibers, significantly suppress dislocation movement, and improve the mechanical properties of the alloy.

[0099] In summary, the Cu-Ag alloy wire prepared using the process and parameters of this invention exhibits excellent comprehensive performance, with an ultimate tensile strength of not less than 1050 MPa, a high-temperature softening temperature of not less than 341 ℃, and a conductivity of not less than 75% IACS.

Claims

1. A high-strength, high-conductivity Cu-Ag alloy, characterized in that, It comprises, by weight percentage: 10-20% Ag, 0.01-0.3% Cr, 0.01-0.3% Zr, 0.01-0.3% V, 0.01-0.3% Re, with the balance being copper and unavoidable impurities, wherein Re is at least one of La, Ce, Sc and Y.

2. The high-strength, high-conductivity Cu-Ag alloy as described in claim 1, characterized in that, The total weight percentage of Cr, Zr, V, and Re elements is 0.1-0.7%.

3. The high-strength, high-conductivity Cu-Ag alloy as described in claim 1, characterized in that, The high-strength, high-conductivity Cu-Ag alloy has a conductivity of not less than 75% IACS, an ultimate tensile strength of not less than 1050 MPa, and a high-temperature softening temperature of not less than 341 ℃.

4. A method for preparing a high-strength, high-conductivity Cu-Ag alloy as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Pure copper and pure silver are loaded into a continuous casting furnace. After the furnace cavity is evacuated, an inert protective gas is introduced. The temperature is raised to the point where the pure copper and pure silver melt. Then, an intermediate alloy is added. The furnace is then held at the temperature and then drawn into a billet to obtain Cu-Ag alloy wire. The intermediate alloy includes copper-chromium alloy, copper-zirconium alloy, copper-vanadium alloy and Re-containing alloy. The Re-containing intermediate alloy includes at least one of copper-lanthanum alloy, copper-cerium alloy, copper-scandium alloy and copper-yttrium intermediate alloy. (2) The Cu-Ag alloy wire is subjected to pre-cold drawing, solution treatment and aging treatment in sequence, and then cold drawing and annealing treatment are performed alternately several times to obtain the high-strength and high-conductivity Cu-Ag alloy.

5. The preparation method according to claim 4, characterized in that, In step (1), nitrogen is selected as the inert protective gas, the temperature for melting pure copper and pure silver is 1200-1500 ℃, the heat preservation temperature is 1200-1300 ℃, and the heat preservation time is 15-20 min.

6. The preparation method according to claim 4, characterized in that, In step (2), the total strain of the pre-cold drawing is 2.0-2.5, the strain of each drawing pass is 0.10-0.30, and the drawing speed is 5-10 mm / s.

7. The preparation method according to claim 4, characterized in that, In step (2), the solution treatment temperature is 650℃-750℃, the solution holding time is 4-8 h, and the wire is water-cooled after the solution treatment. The aging treatment temperature is 300 ℃-500 ℃, the heat preservation time is 1-8 h, and the wire is water-cooled after the aging treatment.

8. The preparation method according to claim 4, characterized in that, In step (2), the alternating cold drawing and annealing processes include the first cold drawing process, the first annealing process, the second cold drawing process, the second annealing process, the third cold drawing process, the third annealing process, and the fourth cold drawing process.

9. The preparation method according to claim 8, characterized in that, The total strain of the Cu-Ag alloy wire after the first cold drawing treatment is 4.0-5.0 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 10-15 mm / s. The total strain of the Cu-Ag alloy wire after the second cold drawing treatment is 5.0-5.5 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 8-10 mm / s. The total strain of the Cu-Ag alloy wire after the third cold drawing treatment is 5.5-6.5 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 5-8 mm / s. The total strain of the Cu-Ag alloy wire after the fourth cold drawing treatment is 6.5-7.0 mm / s, with a strain of 0.10-0.30 mm / s per pass and a drawing speed of 3-5 mm / s.

10. The preparation method according to claim 8, characterized in that, The temperature for the first and second annealing treatments was 350 ℃-400 ℃, and the holding time for both treatments was 30-60 min. The temperature for the third annealing treatment was 300 ℃-350 ℃, and the holding time was 10-30 min.

Images