High-strength high-conductivity copper alloy wire and gradient extrusion preparation method

Abstract

The application discloses a preparation method of a high-strength and high-conductivity copper alloy wire rod, which adopts gradient extrusion, extrusion under high-temperature conditions to obtain a copper rod with uniform and small equiaxed crystal structure; large deformation extrusion under medium and low temperature conditions to obtain a copper rod with streamline fiber structure; and multi-pass drawing treatment to obtain a copper alloy wire rod with elongated fiber structure along the radial direction of the wire rod. The copper alloy wire rod has high tensile strength and high conductivity, and solves the contradiction that the copper alloy wire rod cannot simultaneously meet high strength and high conductivity in the prior art.

Description

Technical Field

[0001] This invention relates to the field of metal processing technology, specifically to a high-strength, high-conductivity copper alloy wire and a gradient extrusion preparation method. Background Technology

[0002] Copper alloys are a fundamental material widely used in the national economy. High-tech fields such as transportation, aerospace, drones, and intelligent robots have increasingly higher demands for the strength and conductivity of copper alloys. High-strength, high-conductivity copper alloy wires are beneficial for product lightweighting and rapid signal transmission. Pure copper wire lacks sufficient mechanical properties when processed into micro-wires, making it unable to meet application requirements. Improving the strength of copper-based materials is divided into composite and solid solution methods. Composite methods offer significant advantages in improving the strength and conductivity of copper, but processing them into micro-wires presents significant technical challenges. Solid solution copper alloys are widely used for strengthening copper alloy micro-wires; however, the strength and conductivity of copper alloys are contradictory. Increasing the content of solid solution elements and cold deformation processing can improve the wire's strength, but this significantly reduces conductivity. It is fundamentally impossible to simultaneously meet the performance requirements of high strength and high conductivity.

[0003] CN117604319A discloses a high-strength, high-conductivity copper alloy wire and its preparation method. This method improves mechanical properties by adding Zr and Cr elements to refine the grains and precipitate a network of Cr reinforcing phases. However, due to its precipitated copper alloy nature, it faces significant technical challenges in processing into micro-wires, making it difficult to achieve micro-wire density. CN113774229B discloses a processing technology for high-strength, high-conductivity, and high-purity copper wire. This method improves the grain size of the wire and eliminates internal stress by continuously extruding and repeatedly performing crystallization annealing, controlling the gradual increase in crystallization annealing temperature and holding time. This improves the electrical conductivity of the copper wire. However, after multiple recrystallizations, it is difficult to effectively improve the wire's strength, and the presence of numerous grain boundaries further hinders the improvement of the copper wire's strength and conductivity. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a gradient extrusion method for preparing high-strength, high-conductivity copper alloy wires. The copper alloy wires of this invention possess high tensile strength and high conductivity, resolving the contradiction in existing technologies where copper alloy wires cannot simultaneously achieve both high strength and high conductivity.

[0005] The objective of this invention is achieved through the following approach: A method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Ingot production: Weigh each component according to the proportion of high-strength and high-conductivity copper alloy wire, and melt and cast it into ingots with a diameter of φ180~φ200mm; 2) First hot extrusion: The ingot is heated to 850-950℃, homogenized, and extruded into a copper rod with a uniform and fine equiaxed crystal structure under an extrusion ratio of 10:1-20:1. 3) Second hot extrusion: The copper rod is heated to 200-300℃, kept at that temperature, and extruded into a copper rod with a streamlined fibrous structure under an extrusion ratio of 10:1-40:1. 4) Drawing process: The copper rod is drawn through multiple passes to obtain a copper alloy wire with a fine fibrous structure along the wire diameter direction.

[0006] The melting and casting described in step 1) is carried out in a vacuum induction furnace with a vacuum degree ≤ 5.0 × 10⁻⁶. -2 Pa, heating temperature is 1100℃-1300℃, holding time is 10-20min, and refining is performed at least 3 times.

[0007] The homogenization process in step 2) takes 4 to 6 hours.

[0008] The diameter of the copper rod in step 2) is 50-60 mm, and the equiaxed crystalline grain size of the copper rod is 50-100 μm.

[0009] The heat preservation time in step 3) is 1 to 2 hours.

[0010] Step 3) The diameter of the copper rod is 8-12mm.

[0011] In step 4), when the diameter of the copper rod to be drawn is ≥3mm, the deformation amount per drawing pass is 15%-25%, and the drawing speed is 10-50m / min; when the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per drawing pass is 10%-15%, and the drawing speed is 50-400m / min.

[0012] The copper alloy wire contains copper, tin, rare earth elements, and transition metal elements. The mass percentage of each component is as follows: tin: 0.05-0.45%, rare earth elements: 0.005-0.020%, transition metal elements: 0.005-0.020%, and copper is the balance.

[0013] The rare earth elements include one or more of La, Ce, and Y; the transition metal elements include one or more of Cr, Zr, and Ti.

[0014] The copper used is oxygen-free copper with a purity of 99.99% or higher.

[0015] The advantages of this invention are: 1. The method described in this invention employs high-temperature hot extrusion (extrusion ratio 10:1 to 20:1). At high temperatures (850℃ to 950℃), the dislocation deformation generated by extrusion drives the dynamic recrystallization of the copper alloy, forming a uniform and fine (50~100μm) equiaxed grain structure, achieving fine grain strengthening, providing a certain strength to the material, and laying the foundation for subsequent fibrous structures. At the same time, the hot extrusion process solves the problem of coarse columnar grain structure and internal defects (porosity, dendrite segregation) generated during casting, improving the plasticity and density of the material.

[0016] 2. This invention utilizes medium-low temperature (200-300℃) high-pressure extrusion (extrusion ratio 10:1-40:1) to process copper rods based on high-temperature extruded bars. The resulting copper rods exhibit elongated grains along the extrusion direction, forming a distinct fibrous streamline structure and numerous deformation bands and dislocation entanglements, thus enhancing the material's strength. During subsequent drawing processes, the fibrous structure is further elongated and refined, resulting in long, thin fibers along the wire diameter. This provides excellent strength to the wire while simultaneously reducing grain boundaries along the wire diameter, lowering the barrier to electron movement in that direction, thereby reducing the impact of cold working on conductivity and improving the wire's conductivity.

[0017] 3. The functions of trace rare earth elements and transition elements in the copper alloy wire of this invention are as follows: Trace rare earth elements readily react with harmful elements such as oxygen, sulfur, and lead in the copper matrix to form compounds, thereby eliminating them from the matrix and purifying it. Simultaneously, they provide heterogeneous nucleation sites, refining grains and hindering grain growth. Trace transition elements have strong atomic binding energy with copper, reducing the grain boundary diffusion coefficient and inhibiting grain growth at high temperatures. The synergistic effect of these two trace elements is beneficial for controlling grain size during subsequent high-temperature extrusion and hindering the recrystallization of fiber structures during medium- and low-temperature extrusion.

[0018] 4. The method described in this invention can also be used for solid solution-treated high-strength, high-conductivity copper alloys, such as copper-magnesium alloys and copper-silver alloys.

[0019] The method described in this invention employs gradient extrusion, i.e., extrusion under high temperature conditions, to obtain a copper rod with a uniform and fine equiaxed crystal structure; large deformation extrusion under medium and low temperature conditions, to obtain a copper rod with a streamlined fibrous structure; and through multiple drawing processes, to obtain a copper alloy wire with a fine and long fibrous structure along the wire diameter direction.

[0020] The applicant's experiments show that when the diameter of the high-strength, high-conductivity copper alloy wire prepared by the method described in this invention is 0.9 mm, the conductivity is >86% IACS and the tensile strength is >570 MPa. Therefore, the copper alloy wire has high tensile strength and high conductivity. Attached Figure Description

[0021] Figure 1This is a tissue diagram after the first compression in Example 1; Figure 2 This is a tissue diagram after the second compression in Example 1; Figure 3 The second extrusion tissue diagram of Comparative Example 1 without the addition of trace elements; Figure 4 The radial fibers of the wire in Example 1; Figure 5 For comparison example 2, radial fibers of general process wires. Detailed Implementation

[0022] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. Example 1

[0023] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.83% oxygen-free copper rod, 0.15% tin, 0.01% rare earth element La, and 0.01% Cr by mass and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1; the metallographic structure is as follows. Figure 1 As shown, the grain size is 50–100 μm; 3) After holding the extruded φ50mm copper rod at 250℃±5℃ for 1 hour, extrude it into a φ8mm copper rod at an extrusion ratio of 39:1; the metallographic structure is as follows. Figure 2 As shown, it is a fibrous streamline structure; 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20%, and the drawing speed is 40m / min; when the diameter of the copper rod is 0.9mm ≤ 3mm, the deformation per pass is 15%, and the drawing speed is 100m / min, resulting in a copper alloy wire with a diameter of 0.9mm. The texture is as follows: Figure 4 As shown, this is a long fiber texture.

[0024] The high-strength, high-conductivity copper alloy wire prepared in Example 1 was tested and found to have a tensile strength of 576 MPa and a conductivity of 87.6% IACS. Example 2

[0025] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.826% oxygen-free copper rod, 0.15% tin, 0.012% rare earth elements La+Ce+Y (ratio 1:1:1), and 0.012% Cr+Zr+Ti (ratio 1:1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ200mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4.5h, copper rods with a diameter of φ60mm were extruded at an extrusion ratio of 11.11:1. 3) After holding the extruded φ60mm copper rod at 300℃±5℃ for 1 hour, extrude a φ12mm copper rod at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20%, and the drawing speed is 40m / min; when the diameter of the copper rod is 0.9mm ≤ 3mm, the deformation per pass is 15%, and the drawing speed is 100m / min, resulting in a copper alloy wire with a diameter of 0.9mm. The texture is as follows: Figure 4 As shown, this is a long fiber texture.

[0026] The high-strength, high-conductivity copper alloy wire prepared in Example 2 was tested and found to have a tensile strength of 585 MPa and a conductivity of 87.5% IACS. Example 3

[0027] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.78% oxygen-free copper rod, 0.20% tin, 0.01% rare earth element La, and 0.01% Cr by mass and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1. 3) After holding the extruded φ50mm copper rod at 250℃±5℃ for 1 hour, extrude it into a φ10mm copper rod at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 200m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0028] The high-strength, high-conductivity copper alloy wire prepared in Example 3 was tested and found to have a tensile strength of 586 MPa and a conductivity of 87.3% IACS. Example 4

[0029] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.78% oxygen-free copper rod, 0.20% tin, 0.01% rare earth La+Y (ratio 1:1), and 0.01% Cr+Ti (ratio 1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ200mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4.5h, copper rods with a diameter of φ60mm were extruded at an extrusion ratio of 11.11:1. 3) After holding the extruded φ60mm copper rod at 250℃±5℃ for 1 hour, extrude a φ12mm copper rod at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 200m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0030] The high-strength, high-conductivity copper alloy wire prepared in Example 4 was tested and found to have a tensile strength of 591 MPa and a conductivity of 87% IACS. Example 5

[0031] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.73% oxygen-free copper rod, 0.25% tin, 0.01% rare earth element La, and 0.01% Cr by mass and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1. 3) After holding the extruded φ50mm copper rod at 250℃±5℃ for 1 hour, extrude it into a φ10mm copper rod at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 200m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0032] The high-strength, high-conductivity copper alloy wire prepared in Example 5 was tested and found to have a tensile strength of 593 MPa and a conductivity of 86.9% IACS. Example 6

[0033] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.73% oxygen-free copper rod, 0.25% tin, 0.01% rare earth elements La+Ce (ratio 1:1), and 0.01% Zr+Cr (ratio 1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. - 2 Pa, start heating, heat to 1200℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ200mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4.5h, extrude a φ50mm copper rod at an extrusion ratio of 16:1; 3) After holding the extruded φ50mm copper rod at 300℃±5℃ for 1 hour, extrude φ10mm copper rods at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 200m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0034] The high-strength, high-conductivity copper alloy wire prepared in Example 6 was tested and found to have a tensile strength of 605 MPa and a conductivity of 86.6% IACS. Example 7

[0035] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.63% oxygen-free copper rod, 0.35% tin, 0.01% rare earth element La, and 0.01% Cr by mass and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1. 3) After holding the extruded φ50mm copper rod at 250℃±5℃ for 1 hour, extrude it into a φ10mm copper rod at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 200m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0036] The high-strength, high-conductivity copper alloy wire prepared in Example 7 was tested and found to have a tensile strength of 610 MPa and a conductivity of 86.3% IACS. Example 8

[0037] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.63% oxygen-free copper rod, 0.35% tin, 0.015% rare earth Y+Ce (ratio 1:1), and 0.005% Zr+Cr (ratio 1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. - 2 Pa, start heating, heat to 1200℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ200mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 5 hours, extrude a φ50mm copper rod at an extrusion ratio of 16:1. 3) After holding the extruded φ50mm copper rod at 300℃±5℃ for 1 hour, extrude φ8mm copper rods at an extrusion ratio of 39:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation per pass is 15% and the drawing speed is 250m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0038] The high-strength, high-conductivity copper alloy wire prepared in Example 8 was tested and found to have a tensile strength of 617 MPa and a conductivity of 86.1% IACS. Example 9

[0039] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 99.83% oxygen-free copper rod, 0.15% magnesium, 0.015% rare earth Y+Ce (ratio 1:1), and 0.005% Zr+Cr (ratio 1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. - 2 Pa, start heating, heat to 1250℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ200mm water-cooled copper mold; 2) After homogenizing the ingot at 950℃±10℃ for 4 hours, extrude a φ50mm copper rod at an extrusion ratio of 16:1. 3) After holding the extruded φ50mm copper rod at 300℃±5℃ for 1 hour, extrude φ10mm copper rods at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation per pass is 15% and the drawing speed is 250m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0040] The high-strength, high-conductivity copper alloy wire prepared in Example 9 was tested and found to have a tensile strength of 581 MPa and a conductivity of 88.3% IACS. Example 10

[0041] A gradient extrusion method for preparing high-strength, high-conductivity copper alloy wire includes the following steps: 1) Weigh out 97.98% oxygen-free copper rod, 2.00% silver, 0.01% rare earth Y+Ce (ratio 1:1), and 0.01% Zr+Cr (ratio 1:1) and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. - 2 Pa, start heating, heat to 1150℃±20℃ and hold for 10 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 850℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1. 3) After holding the extruded φ50mm copper rod at 300℃±5℃ for 1 hour, extrude φ10mm copper rods at an extrusion ratio of 25:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20% and the drawing speed is 30m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation per pass is 15% and the drawing speed is 250m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0042] The test results showed that the high-strength, high-conductivity copper alloy wire prepared in Example 9 had a tensile strength of 587 MPa and a conductivity of 91.5% IACS.

[0043] Comparative Example 1

[0044] 1) Weigh out 99.85% oxygen-free copper rod and 0.15% tin by mass, place them in a graphite crucible, and evacuate the furnace to a vacuum level ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold; 2) After homogenizing the ingot at 900℃±10℃ for 4 hours, copper rods with a diameter of φ50mm were extruded at an extrusion ratio of 12.96:1. 3) After holding the extruded φ50mm copper rod at 300℃±5℃ for 1 hour, extrude φ8mm copper rods at an extrusion ratio of 39:1. 4) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation per pass is 20% and the drawing speed is 40m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation per pass is 15% and the drawing speed is 100m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0045] The copper alloy wire prepared in Comparative Example 1 was tested and found to have a tensile strength of 536 MPa and a conductivity of 85.3% IACS. Its metallographic structure is as follows. Figure 3 As shown.

[0046] Comparative Example 1 with Example 1 ( Figure 3 and Figure 2 Since there are no trace elements in the composition, although there is hot extrusion at different temperatures in the preparation process, the rod material showed a certain degree of recovery recrystallization after the second extrusion. The wire did not have a fine and long fibrous structure. The tensile strength and conductivity of the obtained copper alloy wire were lower than those of Examples 1-8.

[0047] Comparative Example 2

[0048] 1) Weigh out 99.83% oxygen-free copper rod, 0.15% tin, 0.01% rare earth element La, and 0.01% Cr by mass and place them in a graphite crucible. In a vacuum induction furnace, evacuate the vacuum to ≤5.0×10⁻⁶. -2 Pa, start heating, heat to 1200℃±20℃ and hold for 15 minutes, repeat refining 3 times, pour into φ180mm water-cooled copper mold, and use wire cutting to cut into small pieces for easy subsequent processing; 2) Place the alloy block into the bottom-feed continuous casting machine and evacuate to a vacuum level of ≤5.0×10⁻⁶. -2Pa, argon gas is introduced, and heating is started to 1200℃. The temperature is held for 20 minutes. The speed of the derrick in the downward continuous casting is 100 mm / min. The cooling water temperature in the downward continuous casting is 25℃, and the cooling water flow rate is 30 L / min. The continuous casting is carried out to form a copper rod with a diameter of 8 mm. 3) The copper rod is drawn in multiple passes. When the diameter of the copper rod is ≥3mm, the deformation amount per pass is 20% and the drawing speed is 40m / min. When the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per pass is 15% and the drawing speed is 100m / min, to obtain a copper alloy wire with a diameter of 0.9mm.

[0049] The copper alloy wire prepared in Comparative Example 2 was tested and found to have a tensile strength of 513 MPa and a conductivity of 85.6% IACS. Its texture pattern is shown below. Figure 5 As shown, compared with Example 1 Figure 4 Compare, Figure 5 The dense short fiber structure indicates that Comparative Example 2 did not use an extrusion process and also lacked a fine long fiber structure. The tensile strength and conductivity of the resulting copper alloy wire were lower than those of Examples 1-8.

[0050] Conclusion: The high-strength, high-conductivity copper-tin alloy wire prepared by the method described in this invention exhibits a fine fibrous microstructure due to the addition of trace elements to the alloy composition and multiple hot extrusions. The copper alloy wire simultaneously possesses high tensile strength and high conductivity.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high-strength, high-conductivity copper alloy wire and a gradient extrusion preparation method, characterized in that, Includes the following steps: 1) Ingot production: Weigh each component according to the proportion of high-strength and high-conductivity copper alloy wire, and melt and cast it into ingots with a diameter of φ180~φ200mm; 2) First hot extrusion: The ingot is heated to 850-950℃, homogenized, and extruded into a copper rod with a uniform and fine equiaxed crystal structure under an extrusion ratio of 10:1-20:

1. The copper rod has a diameter of 50-60 mm and the equiaxed crystal grain size of the copper rod is 50-100 μm. 3) Second hot extrusion: The copper rod is heated to 200-300℃, kept at that temperature, and extruded into a copper rod with a streamlined fibrous structure under an extrusion ratio of 10:1-40:

1. 4) Drawing process: The copper rod is drawn through multiple passes to obtain a copper alloy wire with a fine fibrous structure along the wire diameter direction; The copper alloy wire contains copper, tin, rare earth elements, and transition metal elements. The mass percentage of each component is as follows: tin: 0.05-0.45%, rare earth elements: 0.005-0.020%, transition metal elements: 0.005-0.020%, and copper is the balance. The rare earth elements include one or more of La, Ce, and Y; the transition metal elements include one or more of Cr, Zr, and Ti.

2. The preparation method according to claim 1, characterized in that: The smelting and casting described in step 1) are carried out in a vacuum induction furnace with a vacuum degree ≤ 5.0 × 10⁻⁶. -2 Pa, heating temperature is 1100℃-1300℃, holding time is 10-20min, and refining is performed at least 3 times.

3. The preparation method according to claim 1, characterized in that: The homogenization process in step 2) takes 4 to 6 hours.

4. The preparation method according to claim 1, characterized in that: The heat preservation time in step 3) is 1 to 2 hours.

5. The preparation method according to claim 1, characterized in that: Step 3) The diameter of the copper rod is 8-12mm.

6. The preparation method according to claim 1, characterized in that: In step 4), when the diameter of the copper rod to be drawn is ≥3mm, the deformation amount per drawing pass is 15%-25%, and the drawing speed is 10-50m / min; when the diameter of the copper rod is 0.9mm≤3mm, the deformation amount per drawing pass is 10%-15%, and the drawing speed is 50-400m / min.

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