Copper-tin-silver-zirconium alloy wire containing composite rare earth elements and continuous preparation process of copper-tin-silver-zirconium alloy wire

Abstract

The alloy wire comprises the following components in percentage by mass: 0.1 to 6.0 weight percent of Sn, 0.1 to 0.3 weight percent of Ag, 0.01 to 0.20 weight percent of Zr, 0.02 to 1.00 weight percent of Y, 0.02 to 2.00 weight percent of Ce, 0.01 to 0.80 weight percent of Eu, 0.01 to 0.50 weight percent of Rb, Y / (Ce + Eu + Rb) is more than or equal to 0.8 and less than or equal to 1.2, and the balance of Cu and inevitable impurities of which the total amount is less than or equal to 0.05 weight percent. According to the invention, Ag and Zr are added into the copper-tin alloy wire in component design, and composite rare earth elements are also added, so that the addition amount of each rare earth element is limited, and in order to further improve the processability and comprehensive performance of the alloy wire, the addition amount of each rare earth element is limited; and finally, the preparation process of vacuum melting-continuous casting technology-multi-pass drawing combined with on-line dynamic annealing process treatment is combined, so that work hardening and internal stress of the wire are eliminated, the machining precision, plasticity and conductivity of the wire are improved, the material performance is more uniform, and the subsequent deformation or cracking risk in use is reduced.

Description

Technical Field

[0001] This invention belongs to the field of alloy wire technology, specifically relating to a copper-tin-silver-zirconium alloy wire containing composite rare earth elements and its continuous preparation process. Background Technology

[0002] In recent years, with the continuous development of fields such as electronic circuits, aerospace, and new energy vehicles, the demand for high-strength, high-conductivity copper alloy materials has gradually increased. Cu-Sn alloys, with their high strength, high conductivity, and excellent corrosion resistance, have become key materials for manufacturing wiring harnesses in new energy vehicles. Cu-Sn-Ag-Zr alloys can overcome the shortcomings of traditional Cu-Sn alloys, exhibiting better conductivity, thermal stability, fatigue resistance, and corrosion resistance. In recent years, with the sales of new energy vehicles repeatedly reaching new highs, Cu-Sn alloys have become the main material for wiring harnesses used in new energy vehicles due to their excellent strength and conductivity.

[0003] However, traditional Cu-Sn alloys have long been limited by defects such as alloy element segregation, casting porosity, and cracks, making it difficult to synergistically improve material strength and conductivity, severely affecting wire processing performance, end-application reliability, and production efficiency. Therefore, there is an urgent need to research and develop copper-tin alloy wires with superior performance through technological innovation to meet the development requirements of the new energy vehicle sector. Chinese patent CN118147482A discloses a high-strength, high-conductivity rare-earth copper-tin alloy and its preparation method. By adding Zn, Ti, and rare-earth element Y to the alloy, it achieves both increased copper alloy strength and improved conductivity. However, this method cannot effectively solve problems such as alloy surface defects and casting cracks. Chinese patent CN114472578A discloses a Re-doped copper-tin alloy contact wire and its preparation method. During the casting process, Re element is added in a holding furnace, then continuously cast into an upper copper rod. The upper copper rod is then extruded into a stretching rod through a continuous extrusion process. Finally, a Re-doped copper-tin alloy contact wire with an alloy composition of Cu-Sn-Re is obtained through a four-die continuous stretching process. However, this method cannot precisely control the alloy composition and cannot effectively improve the problem of dendrite segregation in the alloy.

[0004] Therefore, there is an urgent need for a method that coordinates the alloy composition and the preparation process to improve the poor performance of wires caused by alloy composition segregation, casting defects, etc., so that the alloy wires can take into account both material strength and conductivity, thereby meeting the needs of large-scale continuous production of high-performance copper-tin alloy wires. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-tin-silver-zirconium alloy wire containing composite rare earth elements and its continuous preparation process, so as to solve the problems that the alloy composition and preparation process cannot work synergistically, resulting in the alloy wire being unable to achieve both material strength and conductivity, as well as the problems that the alloy composition is prone to segregation and casting defects.

[0006] To achieve the above objectives, the first aspect of the present invention provides a copper-tin-silver-zirconium alloy wire containing composite rare earth elements. The alloy wire comprises, by mass percentage, Sn 0.1-6.0 wt%, Ag 0.1-0.3 wt%, Zr 0.01-0.20 wt%, Y 0.02-1.00 wt%, Ce 0.02-2.00 wt%, Eu 0.01-0.80 wt%, and Rb 0.01-0.50 wt%, satisfying: 0.8 ≤ Y / (Ce+Eu+Rb) ≤ 1.2, with the balance being Cu and unavoidable impurities totaling ≤ 0.05 wt%.

[0007] Preferably, by mass percentage, the alloy wire comprises Sn 0.15-0.7wt%, Ag 0.1-0.3wt%, Zr 0.01-0.20wt%, Y 0.02-1.00wt%, Ce 0.02-2.00wt%, Eu 0.01-0.80wt%, and Rb 0.01-0.50wt%, and satisfies: 0.8≤Y / (Ce+Eu+Rb)≤1.2, with the balance being Cu and unavoidable impurities totaling ≤0.05wt%.

[0008] A second aspect of this invention provides a continuous preparation process for copper-tin-silver-zirconium alloy wire containing composite rare earth elements, comprising the following steps:

[0009] Step 1: Weigh the alloy materials according to the proportion, mix them and add them to the vacuum melting chamber. Melt and hold at 1200-1250℃ for 30-60 minutes, then pour the molten alloy into the holding chamber.

[0010] Step 2: Maintain the temperature of the alloy melt at 1150-1200℃, start the traction machine for continuous preparation, and obtain an alloy rod with a diameter of 8mm;

[0011] Step 3: The alloy rod is drawn into a wire with a diameter of 0.26mm through a multi-pass drawing process combined with online dynamic annealing.

[0012] Preferably, the specific process of step one is as follows:

[0013] Weigh the alloy materials according to the proportion, mix them and add them to the vacuum melting chamber. Then close the chamber door, insert the crystallizer into the flow channel, and then insert one end of the traction copper rod into the crystallizer, while the other end protrudes out of the crystallizer and presses on the traction machine roller.

[0014] The vacuum system is turned on to evacuate the melting chamber and the holding chamber to below 10 Pa. Argon gas is then introduced and heated. The vacuum is then continued to be evacuated to further remove any moisture that may be introduced from the furnace charge. Once the required vacuum level is reached, argon gas is introduced into the melting chamber and the holding chamber to a pressure of 0.5-1.0 atmospheres. Heating is not stopped during this process. The alloy melt is melted and held at 1200-1250℃ for 30-60 minutes. The melted alloy is then poured into the holding chamber.

[0015] Preferably, in step two, the traction speed of the traction machine is 20-30 mm / s, the pitch is 4-5 mm / cycle, the stopping time is 0.3-0.6 s / cycle, the water pressure is 0.2-0.4 MPa, the inlet temperature of the cooling water for the crystallizer is less than 30℃, and the outlet temperature is less than 50℃.

[0016] More preferably, in step two, the traction speed of the traction machine is 25±2mm / s, the pitch is 4-5mm / cycle, the stopping time is 0.3-0.6s / cycle, the water pressure is 0.2-0.4MPa, the inlet temperature of the cooling water for the crystallizer is less than 30℃, and the outlet temperature is less than 50℃.

[0017] Preferably, in step three, the drawing process is carried out in 7-10 passes, with a deformation amount of 20%-25% per pass and a surface reduction rate of 20-45% per pass.

[0018] Preferably, in step three, the annealing temperature is 320-600℃ and the annealing time is 10-40s.

[0019] Preferably, in step three, the alloy rod blank with a diameter of 8mm is drawn to a diameter of 2.6mm, and then a wire with a diameter of 0.26mm is obtained through medium and small drawing. The drawing speed is 1000-2000 meters / minute, and online annealing is set during the drawing process.

[0020] In step three of this invention, multi-pass drawing and online dynamic annealing are two wire processing techniques used in combination. Multi-pass drawing gradually stretches the wire, making it thinner and stronger; while online dynamic annealing heats the wire in real time during the stretching process, helping it restore its structure, eliminate internal stress, and improve ductility. The combination of the two allows the wire to have both high strength and resistance to brittle fracture, thereby improving the overall performance of the material.

[0021] Preferably, the wire has a tensile strength ≥473MPa, elongation ≥0.2, and conductivity ≥75%.

[0022] Therefore, the present invention provides a copper-tin-silver-zirconium alloy wire containing composite rare earth elements with the above-described structure and its continuous preparation process, which has the following beneficial effects:

[0023] (1) In terms of composition design, this invention considers that Cu-Sn binary alloys are solid solution strengthened and work-hardening alloys. Therefore, while ensuring the conductivity of Cu-Sn alloys, it comprehensively considers factors such as solid solution strengthening and work hardening of copper alloys and selects to add trace amounts of Ag. The results show that the addition of trace amounts of Ag can improve the conductivity of Cu-Sn alloys. Furthermore, Ag in Cu-Sn alloys can significantly improve the strength and hardness of the alloy through a solid solution strengthening mechanism, i.e., silver atoms are incorporated into the copper-tin alloy lattice, causing lattice distortion and hindering dislocation movement.

[0024] (2) In designing the alloy element composition, this invention also considers how to improve the oxidation resistance and heat resistance of Cu-Sn alloys. Based on this, this invention selects to add trace amounts of Zr to the material. Zr forms a dense oxide film (such as ZrO2) on the alloy surface, preventing oxygen from further diffusing inward and improving the alloy's oxidation resistance. Zr can also form high-melting-point intermetallic compounds with other elements in the alloy. These intermetallic compounds have good stability at high temperatures. They can pin grain boundaries, hindering grain boundary migration and grain growth, thus enabling the alloy to maintain good microstructure and mechanical properties even at high temperatures. The results show that adding Zr can significantly improve the oxidation resistance, heat resistance, and service life of copper-tin alloys.

[0025] (3) This invention also adds composite rare earth elements Y, Eu, and Rb. These elements react with oxygen to form Y₂O₃, Eu₂O₃, and Rb₂O₂. Eu₂O₃ mainly plays a degassing role, while Rb₂O₂ acts as a catalyst in the melt reaction and works together with Y₂O₃ and Ce to significantly refine the grains. Yttrium has a large difference in affinity with copper and tin, and can preferentially combine with Sn to form Y-Sn intermetallic compounds (such as Y₅Sn₃), reducing Sn segregation between dendrites. This invention achieves the goals of deoxidation, slag removal, and grain refinement through the synergistic effect of multiple composite rare earth elements, thereby improving the dendritic segregation phenomenon of Cu-Sn alloys.

[0026] (4) The vacuum continuous melting and casting apparatus used in this invention can effectively isolate air during the melting and casting process and obtain high-quality alloy rod blanks with fewer casting defects such as porosity and impurity content and lower oxygen content without the use of flux, thus giving the alloy rod blanks good processing performance. Furthermore, through the synergistic process of multi-pass drawing and online dynamic annealing, and through the dynamic cycle of "deformation-softening-re-deformation", ultra-precision, high efficiency and functional customization of copper wire processing are achieved, which is especially suitable for high-end electronics, new energy and other fields with stringent requirements for material performance.

[0027] (5) The process of the present invention can complete the processing of a large number of wires in a short time, reducing production costs and making it suitable for large-scale industrial production. The process of the present invention is simple, the process flow is short, and the alloy has the characteristics of high strength, high conductivity, good heat resistance and oxidation resistance, and the tensile strength is ≥473MPa, the elongation is ≥0.2, and the conductivity is ≥75%.

[0028] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0029] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0030] The alloy raw materials used in the following examples and comparative examples can all be obtained directly through purchase. The specific composition of the examples and comparative examples is shown in Table 1.

[0031] Table 1 Alloy composition of the examples and comparative examples

[0032]

[0033] The preparation methods of the alloy wires in Examples 1-4 and Comparative Examples 1-4 include the following steps:

[0034] Step 1: Preparations before smelting

[0035] After mixing the prepared alloy materials, put them into the vacuum melting chamber, then close the chamber door, insert the crystallizer into the flow channel, and then insert one end of the traction copper rod into the crystallizer, while the other end protrudes out of the crystallizer and presses on the traction machine roller.

[0036] Step Two: Vacuum Melting Process

[0037] The vacuum system was turned on to evacuate the melting chamber and the holding chamber to below 10 Pa. Then argon gas was introduced and heated for a period of time, about 20 minutes. The vacuum was then continued to be evacuated to further remove any moisture that might be brought in by the furnace charge. Once the required vacuum level (below 10 Pa) was reached, argon gas was introduced into the melting chamber and the holding chamber to 0.6 atmospheres. During this process, heating was not stopped. The alloy melt was melted and held at 1220℃ for 40 minutes. The melt was then poured into the holding chamber.

[0038] Step 3: Continuous casting process

[0039] When the temperature of the alloy melt in the insulation chamber is 1180℃, the traction machine is started, the traction speed is 25mm / s, the pitch is 3mm / cycle, the stopping time is 0.3s / cycle, the water pressure is 0.3MPa, the inlet water temperature of the crystallizer cooling water is 32℃, the outlet water temperature is 50℃, and alloy rods with a diameter of 8mm are continuously produced.

[0040] Step 4: Multi-pass drawing combined with online dynamic annealing process

[0041] For an alloy rod blank with a diameter of 8mm, it is drawn to a diameter of 2.6mm, and then drawn again through medium and small draws to obtain a wire with a diameter of 0.26mm. The drawing speed is 1500m / min, with 7 passes, and the surface area reduction rate per pass is about 30%. Online annealing is set during the drawing process, with an annealing temperature of 500℃ and an annealing time of 15s.

[0042] The difference between the preparation method of alloy wire in Example 5 and that in Example 2 is that the annealing treatment in step four is different. The annealing temperature in Example 5 is 450°C and the annealing time is 15s.

[0043] The difference between the preparation method of alloy wire in Example 6 and that in Example 2 is that the annealing treatment in step four is different. The annealing temperature in Example 6 is 550°C and the annealing time is 15s.

[0044] Test case

[0045] The alloy wires of the examples and comparative examples were subjected to performance tests, and the test procedures are as follows:

[0046] Tensile strength and elongation tests:

[0047] The tensile strength and elongation of the alloy wire were tested using a DNS-200 electronic tensile testing machine. The rated load of the universal testing machine was 50 kN, the load-strain test accuracy error was no more than 0.5% of the indicated value, and the tensile speed was 1.56 mm / min. Each tensile test was repeated three times to ensure data reliability. The copper wire was fixed at both ends, and tension was gradually applied until the wire broke. The maximum tensile force was recorded during the experiment, and the tensile strength of the wire was calculated. The elongation was calculated by measuring the original length and the length after breakage of the copper wire.

[0048] Conductivity test:

[0049] The resistivity of the alloy wire to alloy was tested using an intelligent metallic conductor resistivity meter (TX-300A, China). The measured resistivity was then converted into conductivity (%IACS), and the average of five tests was taken as the final result. The test sample was 1000 mm long, the test temperature was 25℃, and the conductivity unit was the International Standard for Annealed Copper (%IACS).

[0050] The test results are shown in Table 2.

[0051] Table 2 Performance test results of alloy wires from the examples and comparative examples.

[0052] elongation Tensile strength (MPa) Electrical conductivity (%IACS) Example 1 0.2 465 83 Example 2 0.2 473 75.3 Example 3 0.2 553 61 Example 4 0.2 574 54.4 Example 5 0.2 468 77.6 Example 6 0.2 470 75.2 Comparative Example 1 0.2 465 71 Comparative Example 2 0.2 471 72.9 Comparative Example 3 0.2 385 86.3 Comparative Example 4 0.2 566 53.5

[0053] As can be seen from Table 1, Example 2 can balance the mechanical properties and electrical conductivity of the alloy wire.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A copper-tin-silver-zirconium alloy wire containing composite rare earth elements, characterized in that, By mass percentage, the alloy wire comprises Sn 0.1-6.0wt%, Ag 0.1-0.3wt%, Zr 0.01-0.20wt%, Y 0.02-1.00wt%, Ce 0.02-2.00wt%, Eu 0.01-0.80wt%, and Rb 0.01-0.50wt%, and satisfies the following condition: 0.8≤Y / (Ce+Eu+Rb)≤1.2, with the balance being Cu and unavoidable impurities totaling ≤0.05wt%.

2. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 1, characterized in that, Includes the following steps: Step 1: Weigh the alloy materials according to the proportion, mix them and add them to the vacuum melting chamber. Melt and hold at 1200-1250℃ for 30-60 minutes, then pour the molten alloy into the holding chamber. Step 2: Maintain the temperature of the alloy melt at 1150-1200℃, start the traction machine for continuous preparation, and obtain an alloy rod with a diameter of 8mm; Step 3: The alloy rod is drawn into a wire with a diameter of 0.26mm through a multi-pass drawing process combined with online dynamic annealing.

3. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, The specific process of step one is as follows: Weigh the alloy materials according to the proportion, mix them and add them to the vacuum melting chamber. Then close the chamber door, insert the crystallizer into the flow channel, and then insert one end of the traction copper rod into the crystallizer, while the other end protrudes out of the crystallizer and presses on the traction machine roller. The vacuum system is turned on to evacuate the melting chamber and the holding chamber to a vacuum level below 10 Pa. Argon gas is then introduced, and after heating, the vacuum is continued to be evacuated to further remove any moisture that may be introduced from the furnace charge. Once the required vacuum level is reached, argon gas is introduced into the melting chamber and the holding chamber to a pressure of 0.5-1.0 atmospheres. Heating is not stopped during this process. After melting and holding at 1200-1250℃ for 30-60 minutes, the molten alloy is poured into the holding chamber.

4. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, In step two, the traction speed of the traction machine is 20-30 mm / s, the pitch is 4-5 mm / cycle, the stopping time is 0.3-0.6 s / cycle, the water pressure is 0.2-0.4 MPa, the inlet temperature of the cooling water for the crystallizer is less than 30℃, and the outlet temperature is less than 50℃.

5. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, In step three, the drawing process goes through 7-10 passes, with a deformation of 20%-25% per pass and a surface reduction of 20-45% per pass.

6. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, In step three, the annealing temperature is 320-600℃ and the annealing time is 10-40s.

7. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, In step three, the alloy rod blank with a diameter of 8mm is drawn to a diameter of 2.6mm, and then the wire with a diameter of 0.26mm is obtained through medium and small drawing. The drawing speed is 1000-2000 meters / minute, and online annealing is set during the drawing process.

8. The continuous preparation process of copper-tin-silver-zirconium alloy wire containing composite rare earth elements according to claim 2, characterized in that, The wire has a tensile strength ≥473MPa, elongation ≥0.2, and conductivity ≥75%.

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