A casting method of high-strength high-conductivity copper-zirconium alloy

Abstract

The application relates to the technical field of metal processing, in particular to a casting method of high-strength high-conductivity copper-zirconium alloy. The casting method of the high-strength high-conductivity copper-zirconium alloy is mainly composed of 0.08-0.35 wt% Zr and the balance of Cu, and the total amount of impurities is not more than 0.01%, and the casting method comprises vacuum smelting, continuous casting, drawing, annealing treatment, drawing, aging treatment, through a controllable environment and fine processing in the whole process, the comprehensive performance of the material is significantly improved, compared with a traditional process, the scheme has advantages in purity, strength, conductivity and processing efficiency, and is especially suitable for high-strength high-conductivity wires, electronic packaging and other high-end fields, and realizes the whole-chain optimization of a 'pure matrix, uniform fine crystal and performance'.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal processing, in particular to a casting method of high-strength high-conductivity copper-zirconium alloy. BACKGROUND

[0002] Copper has excellent electrical conductivity, thermal conductivity, corrosion resistance and weldability, and is widely used in electronic communication, rail transportation, aerospace and other industries. With the development of advanced materials technology, some shortcomings of pure copper gradually appear, such as insufficient strength and easy softening. These shortcomings make pure copper unable to meet the performance requirements in special occasions.

[0003] Micro-alloying is one of the effective ways to improve the comprehensive performance of copper alloy. However, with the addition of alloying elements, the strength of copper alloy is improved, and the electrical conductivity is reduced. Therefore, the reasonable selection of alloying elements and the amount of element addition is a key factor in preparing high-strength high-conductivity high-heat-resistant copper alloy.

[0004] Zr alloying element can form precipitated strengthening phase in copper matrix, which significantly improves the tensile strength of copper alloy while reducing its influence on the electrical conductivity of copper alloy. It is the preferred strengthening element for high-strength high-conductivity copper alloy used in contact lines, lead frames and other fields.

[0005] Cu-Zr alloy not only has excellent electrical conductivity and good plasticity, but also has strong oxidation resistance and good wear resistance. In addition, the addition of zirconium can improve the recrystallization temperature of the alloy, thereby improving the high-temperature softening resistance of the alloy. More importantly, the tensile strength and hardness of Cu-Zr alloy are also significantly improved due to the grain refinement and precipitate strengthening effect of zirconium. Therefore, Cu-Zr alloy has good adaptability at high temperatures and is currently used in electronics, military, national defense, rail transportation and other fields.

[0006] Therefore, in order to realize high-strength and high-conductivity Cu-Zr alloy, the application develops a casting method of high-strength high-conductivity copper-zirconium alloy with low Zr content. SUMMARY

[0007] The application mainly provides a casting method of high-strength high-conductivity copper-zirconium alloy with low Zr content. The method can prepare a high-strength high-conductivity Cu-Zr alloy under the condition of low Zr content. The performance of the prepared Cu-Zr alloy is guaranteed, the production cost is low, and the process flow is short.

[0008] The application provides a casting method of high-strength high-conductivity copper-zirconium alloy, which comprises the following steps:

[0009] The copper-zirconium alloy component comprises 0.08-0.35wt% Zr, the balance is Cu, and the total amount of impurities is ≤0.01%. The method comprises the following casting steps:

[0010] (1) Add the raw materials into the vacuum continuous melting crucible, and evacuate the furnace to <1×10 -1 After Pa, argon gas is introduced into the furnace to a pressure of 0.8-0.9 MPa, and smelting is carried out at 1200-1350℃. After complete melting, it is poured into a holding furnace for holding at 1200-1350℃, and the oxygen content in the melt is <10ppm.

[0011] (2) The molten material after melting is pulled through a horizontal continuous casting equipment at a temperature of 1200-1350℃ to prepare Cu-Zr alloy rod billet;

[0012] (3) Perform the first drawing of the Cu-Zr alloy rod blank;

[0013] (4) Anneal the Cu-Zr alloy rod blank after the first drawing;

[0014] (5) Perform secondary drawing on the annealed Cu-Zr alloy billet;

[0015] (6) The Cu-Zr alloy billet after secondary drawing is subjected to aging treatment to prepare copper-zirconium alloy.

[0016] As a preferred aspect, the Zr and Cu used in the raw materials have a purity of ≥99.99%.

[0017] As a preferred aspect, the crucible in step (1) is specifically a graphite-coated boron nitride crucible.

[0018] This invention uses a graphite-insulated boron nitride crucible. Boron nitride enables rapid melting and exhibits excellent chemical stability against molten Zr at high temperatures, effectively preventing the reaction between Zr and the crucible material. If a graphite crucible is used directly, Zr will react with C to form brittle ZrC, leading to melt contamination and crucible damage.

[0019] As a preferred aspect, the crystallizer material used in the horizontal continuous casting in step (2) is boron nitride.

[0020] The present invention uses a boron nitride crystallizer to ensure the stability of the solidification process and the quality of the ingot.

[0021] As a preferred aspect, in step (2), the horizontal traction speed is 1-8 mm / s, the pitch is 2-6 mm, the pause time is 0.1-0.5 s, the cooling water flow rate is 50-300 L / min, the cooling water inlet temperature is 25-45 ℃, and the Cu-Zr alloy rod blank prepared therein has a diameter of 10-20 mm and an oxygen content of <10 ppm.

[0022] As a preferred aspect, the deformation of the first drawing in step (3) is 60-70%, which constructs the defect structure required for high strength of the alloy, and graphite emulsion is used to assist the drawing.

[0023] As a preferred aspect, the annealing temperature in step (4) is 400-450℃ and the holding time is 30-60min.

[0024] In this invention, annealing balances the properties of strength, plasticity, and conductivity by controlling the stress state, grain structure, and phase composition of the material, and is a key step connecting processing and final application.

[0025] As a preferred aspect, the deformation amount of the secondary drawing in step (5) is 30-40%.

[0026] Based on the fine-grained structure formed by annealing, this invention reconstructs the dislocation structure with a moderate deformation of 30-40%, forming regularly arranged dislocation walls and subgrain structures, which significantly increases the dislocation density and avoids excessive work hardening.

[0027] As a preferred aspect, the aging temperature in step (6) is 350-400℃ and the holding time is 60-180min.

[0028] The present invention also limits the aging temperature and holding time, which can obtain fine, dispersed nano Zr precipitates, significantly reduce lattice distortion, and restore and improve electrical conductivity.

[0029] As a preferred aspect, the raw material composition is preferably 0.1-0.35 wt% Zr, with the balance being Cu, and the total impurities ≤0.01%.

[0030] The present invention has the following advantages:

[0031] 1. The copper-zirconium alloy of this invention employs a combination of processes including vacuum melting, vacuum continuous casting, drawing, annealing, secondary drawing, and aging, which has significant advantages. Vacuum melting improves alloy purity and reduces impurities; vacuum continuous casting improves production efficiency and ensures dimensional accuracy and microstructure uniformity; the first drawing introduces high dislocation density, enhancing strength; annealing eliminates work hardening through partial recrystallization, retains an appropriate amount of dislocation substructure, and balances strength and plasticity; secondary drawing further refines the subgrains, forming regular dislocation walls, providing uniform nucleation sites for aging precipitation. The prepared copper-zirconium alloy can achieve high strength and high conductivity.

[0032] 2. This invention first employs horizontal continuous casting under vacuum melting, avoiding oxidation and impurities in the raw materials. Zirconium (Zr) readily reacts with oxygen and nitrogen to form brittle inclusions. Vacuum melting significantly reduces impurity content, improving the alloy's conductivity, ductility, and fatigue life. It also reduces component loss during melting, ensuring the accuracy of alloy design. Rapid solidification in continuous casting suppresses Zr segregation. Continuous casting grain size can be controlled within 20-50 μm, resulting in high precision, regular shape, high yield, reduced casting defects, and high production efficiency. This significantly shortens the production cycle and reduces overall production costs. Room temperature drawing utilizes work hardening to greatly improve strength while suppressing brittle phase coarsening. Annealing is crucial for performance control; it allows for flexible microstructure adjustment, enabling both low-temperature stress relief to retain strength and medium-temperature recrystallization to restore plasticity.

[0033] 3. Compared to traditional processes, this invention offers significant advantages in purity, strength, conductivity, and processing efficiency, making it particularly suitable for high-end applications such as high-strength, high-conductivity wires and electronic packaging. It achieves full-chain optimization from "pure matrix → uniform fine grains → performance." A graphite-insulated boron nitride crucible is used in vacuum melting, while a boron nitride crystallizer is used in vacuum continuous casting. The boron nitride crucible (with a graphite insert) employs a dual protection mechanism: chemical isolation (inner boron nitride layer) and efficient thermal conduction (outer graphite layer), making it an ideal choice for melting reactive metals while balancing purity control and process efficiency. The boron nitride crystallizer further ensures the stability of the solidification process and the quality of the ingot. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the casting method for the high-strength, high-conductivity copper-zirconium alloy used in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0036] Example 1: A casting method for a high-strength, high-conductivity copper-zirconium alloy, referenced. Figure 1 ,include:

[0037] (1) The alloy composition is 0.1wt% Zr and the balance is Cu. The raw materials are added to the crucible of the vacuum melting furnace. The furnace is evacuated to 0.01Pa and then argon is introduced to the furnace pressure of 0.8MPa. The melting is carried out in the melting furnace at a melting temperature of 1200℃. After it is completely melted, it is poured into the holding furnace for holding at a holding temperature of 1200℃.

[0038] (2) The molten material after melting is pulled through a horizontal continuous casting equipment. The pulling temperature is 1200℃. The crystallizer material used in the horizontal continuous casting is boron nitride. The horizontal pulling speed is 1mm / s, the pitch is 2mm, the pause time is 0.1s, the cooling water flow rate is 50L / min, and the cooling water inlet temperature is 25℃. A Cu-Zr alloy rod billet with a diameter of 10mm and an oxygen content of 3.5ppm is obtained.

[0039] (3) The Cu-Zr alloy rod blank is drawn for the first time, and graphite emulsion is used to assist in the drawing. The deformation of the first drawing is 60-70%;

[0040] (4) The Cu-Zr alloy rod blank after the first drawing is annealed at 400℃ for 30 min to obtain the annealed Cu-Zr alloy rod blank;

[0041] (5) The treated Cu-Zr alloy billet is subjected to secondary drawing, and the deformation amount of the secondary drawing is 30%;

[0042] (6) The Cu-Zr alloy rod blank that has been drawn twice is subjected to aging treatment at a temperature of 350℃ and a holding time of 60min to obtain a copper-zirconium alloy.

[0043] Example 2: A casting method for a high-strength, high-conductivity copper-zirconium alloy, see [link to example]. Figure 1 ,include:

[0044] (1) The alloy composition is 0.2wt% Zr and the balance is Cu. The raw materials are added to the crucible of the vacuum melting furnace. The furnace is evacuated to 0.01Pa and then filled with argon gas to a furnace pressure of 0.9MPa. The melting is carried out in the melting furnace at a melting temperature of 1350℃. After it is completely melted, it is poured into a holding furnace for holding at a holding temperature of 1350℃.

[0045] (2) The molten material after melting is pulled through a horizontal continuous casting equipment. The pulling temperature is 1350℃. The crystallizer material used in the horizontal continuous casting is boron nitride. The horizontal pulling speed is 8mm / s, the pitch is 6mm, the pause time is 0.5s, the cooling water flow rate is 300L / min, and the cooling water inlet temperature is 45℃. A Cu-Zr alloy rod billet with a diameter of 20mm and an oxygen content of 2.3ppm is obtained.

[0046] (3) The Cu-Zr alloy billet was first drawn, and graphite emulsion was used to assist in the drawing. The deformation of the first drawing was 60%.

[0047] (4) The Cu-Zr alloy rod blank after the first drawing is annealed at 450℃ for 60 min to obtain the annealed Cu-Zr alloy rod blank;

[0048] (5) The treated Cu-Zr alloy billet is subjected to secondary drawing, and the deformation amount of the secondary drawing is 30%;

[0049] (6) The Cu-Zr alloy rod blank drawn twice was subjected to aging treatment at an aging temperature of 400℃ and a holding time of 180min to obtain copper-zirconium alloy.

[0050] Example 3: A casting method for a high-strength, high-conductivity copper-zirconium alloy, see [link to example]. Figure 1 ,include:

[0051] (1) The alloy composition is 0.35wt% Zr and the balance is Cu. The raw materials are added to the crucible of the vacuum melting furnace. The furnace is evacuated to 0.01Pa and then filled with argon gas to a furnace pressure of 0.8MPa. The melting is carried out in the melting furnace at a melting temperature of 1200℃. After it is completely melted, it is poured into a heat preservation furnace for heat preservation at a temperature of 1200℃.

[0052] (2) The molten material after melting is pulled through a horizontal continuous casting equipment. The pulling temperature is 1200℃. The crystallizer material used in the horizontal continuous casting is boron nitride. The horizontal pulling speed is 1mm / s, the pitch is 2mm, the pause time is 0.1s, the cooling water flow rate is 50L / min, and the cooling water inlet temperature is 25℃. A Cu-Zr alloy rod billet with a diameter of 10mm and an oxygen content of 1.2ppm is obtained.

[0053] (3) The Cu-Zr alloy billet was first drawn, and graphite emulsion was used to assist in the drawing. The deformation of the first drawing was 70%.

[0054] (4) The Cu-Zr alloy rod blank after the first drawing is annealed at 400℃ for 30 min to obtain the annealed Cu-Zr alloy rod blank;

[0055] (5) The treated Cu-Zr alloy billet is subjected to secondary drawing, and the deformation amount of the secondary drawing is 40%;

[0056] (6) The Cu-Zr alloy rod blank that has been drawn twice is subjected to aging treatment at a temperature of 350℃ and a holding time of 60min to obtain a copper-zirconium alloy.

[0057] Example 4: A casting method for a high-strength, high-conductivity copper-zirconium alloy, see [link to example]. Figure 1 ,include:

[0058] (1) The alloy composition is 0.3wt% Zr and the balance is Cu. The raw materials are added to the crucible of the vacuum melting furnace. The furnace is evacuated to 0.01Pa and then argon is introduced to the furnace pressure of 0.9MPa. The melting is carried out in the melting furnace at a melting temperature of 1300℃. After it is completely melted, it is poured into the holding furnace for holding at a holding temperature of 1300℃.

[0059] (2) The molten material after melting is pulled through a horizontal continuous casting equipment. The pulling temperature is 1250℃. The crystallizer material used in the horizontal continuous casting is boron nitride. The horizontal pulling speed is 7mm / s, the pitch is 5mm, the pause time is 0.2s, the cooling water flow rate is 100L / min, and the cooling water inlet temperature is 35℃. A Cu-Zr alloy rod billet with a diameter of 10mm and an oxygen content of 1.7ppm is obtained.

[0060] (3) The Cu-Zr alloy billet was first drawn, and graphite emulsion was used to assist in the drawing. The deformation of the first drawing was 60%.

[0061] (4) The Cu-Zr alloy rod blank after the first drawing is annealed at 400℃ for 30 min to obtain the annealed Cu-Zr alloy rod blank;

[0062] (5) The treated Cu-Zr alloy billet is subjected to secondary drawing, and the deformation amount of the secondary drawing is 40%;

[0063] (6) The Cu-Zr alloy rod blank drawn twice was subjected to aging treatment at an aging temperature of 400℃ and a holding time of 180min to obtain copper-zirconium alloy.

[0064] The tensile strength and electrical conductivity of the copper-zirconium alloys prepared in Examples 1-4 were measured, and the results are shown in Table 1.

[0065] Table 1. Performance determination of copper-zirconium alloys in Examples 1-4

[0066] Tensile strength (MPa) Electrical conductivity (% IACS) Example 1 498 88.2 Example 2 583 82.6 Example 3 758 71.4 Example 4 684 76.8

[0067] As can be seen from the data in Table 1, the copper-zirconium alloy prepared by this invention achieves high strength and high conductivity.

[0068] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A casting method for a high-strength, high-conductivity copper-zirconium alloy, characterized in that, The copper-zirconium alloy composition is 0.08-0.35% Zr by mass, with the balance being Cu, and the total impurities ≤0.01%. It includes the following casting steps: (1) Add the raw materials into the vacuum continuous melting crucible, and evacuate the furnace to <1×10 -1 After Pa, argon gas is introduced into the furnace to a pressure of 0.8-0.9 MPa, and smelting is carried out at 1200-1350℃. After complete melting, it is poured into a holding furnace for holding at 1200-1350℃, and the oxygen content in the melt is <10ppm. (2) The molten material after melting is pulled through a horizontal continuous casting equipment at a temperature of 1200-1350℃ to prepare Cu-Zr alloy rod billet; (3) Perform the first drawing of the Cu-Zr alloy rod blank; (4) Anneal the Cu-Zr alloy rod blank after the first drawing; (5) Perform secondary drawing on the annealed Cu-Zr alloy billet; (6) The Cu-Zr alloy billet after secondary drawing is aged to prepare copper-zirconium alloy. The crucible in step (1) is a graphite-coated boron nitride crucible. The crystallizer material used in the horizontal continuous casting in step (2) is boron nitride. The deformation amount of the first drawing in step (3) is 60-70%, and graphite emulsion is used to assist the drawing. The annealing temperature in step (4) is 400-450℃ and the holding time is 30-60min. The aging temperature in step (6) is 350-400℃ and the holding time is 60-180min. The deformation amount of the second drawing in step (5) is 30-40%.

2. The casting method of a high-strength, high-conductivity copper-zirconium alloy according to claim 1, characterized in that, The Zr and Cu used in the raw materials have a purity of ≥99.99%.

3. The casting method of a high-strength, high-conductivity copper-zirconium alloy according to claim 1, characterized in that, In step (2), the horizontal traction speed is 1-8 mm / s, the pitch is 2-6 mm, the pause time is 0.1-0.5 s, the cooling water flow rate is 50-300 L / min, and the cooling water inlet temperature is 25-45 ℃. The Cu-Zr alloy rod blank prepared has a diameter of 10-20 mm and an oxygen content of <10 ppm.

4. The casting method of a high-strength, high-conductivity copper-zirconium alloy according to claim 1, characterized in that, The raw material composition is 0.1-0.35% Zr by mass, with the balance being Cu, and the total impurities are ≤0.01%.

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