CN115074564A - Preparation method of high-strength high-conductivity copper-chromium-zirconium alloy - Google Patents

Abstract

The present application discloses a method for preparing a high-strength and high-conductivity copper-chromium-zirconium alloy. Its components are: chromium: 0.8-1.2wt.%; zirconium: 0.1-0.5wt.%; The preparation method includes multi-stage cold deformation and heat treatment, followed by vacuum horizontal continuous casting, first cold deformation, solid solution treatment, second cold deformation, aging treatment and third cold deformation. By this method, the needle-like primary phase can be regulated into spherical shape; there are a large number of nano-layered structures, substructures and spherical primary phases distributed in grain boundaries in the obtained copper-chromium-zirconium alloy. The copper-chromium-zirconium alloy with this structure has a tensile strength of more than 700 MPa and a maximum of more than 800 MPa, and an electrical conductivity of more than 75% IACS, which can quickly adapt to industrialized continuous mass production.

Description

A kind of preparation method of high-strength and high-conductivity copper-chromium-zirconium alloy

technical field

The invention belongs to the technical field of copper alloys, and more particularly relates to a preparation method of a high-strength and high-conductivity copper-chromium-zirconium alloy.

Background technique

In recent years, on the one hand, with the gradual increase in the speed of high-speed railways, higher requirements have been placed on the strength and conductivity of copper alloy contact wires; on the other hand, electronic and electrical equipment and drones are moving towards miniaturization, lightness This requires copper alloys not only to have high strength and high electrical conductivity, but also to meet the requirements of small wire diameter (thin thickness) and good stability. In the future, high-performance copper alloys will develop in the direction of double 70 alloys, that is, the tensile strength is not less than 700MPa, and the electrical conductivity is not less than 70% IACS. The tensile strength and electrical conductivity of copper-chromium-zirconium alloy are expected to meet the requirements, but its composition uniformity is unstable. Few domestic enterprises can stably produce large-length, heavy-volume ingots. Currently, it is urgent to break through high-strength and high-conductivity copper. Chromium-zirconium alloy large coil heavy, continuous key billet making technology. Upward continuous casting is an optional method, and some companies have produced it. However, upward continuous casting still has problems such as low purity of alloy melt, inconsistent composition of head and tail, uneven surface quality, etc., and the vacuum level Continuous casting can solve these problems. First of all, keep the raw materials clean, ensure that the melt will not oxidize and form slag under vacuum, and the gas protection at the outlet of the mold can also ensure the surface quality of the product.

During the casting process of copper-chromium-zirconium alloys, coarse chromium-rich primary phases are prone to appear. In addition to the precipitation strengthening phase, the distribution and morphology of the primary phase in the Cu-Cr-Zr alloy also have an important influence on the properties of the alloy. When the morphology of the primary phase is elongated and regular prismatic, it is easy to cause cracks to grow and spread, which obviously affects the mechanical properties of the alloy; when the primary phase is small and spherical, it can significantly improve the strength of the alloy and improve its comprehensive mechanical properties. The primary phase regulation is mostly by adjusting the casting parameters during solidification, thereby controlling the morphology and size of the primary phase, such as controlling the cooling rate. In fact, the morphology and distribution of the primary phase can also be regulated during the subsequent deformation and heat treatment.

The patent document with the publication number of CN104342575B discloses a preparation method for obtaining a copper-chromium-zirconium continuous casting billet with a large length and a large section by vacuum melting and vacuum horizontal continuous casting. However, the highest tensile strength is only 620MPa, which is still far from the current goal of "Double 70" (tensile strength ≥700MPa, electrical conductivity ≥70% IACS).

The patent document with the publication number CN110055479B discloses an 800MPa grade high-conductivity copper-chromium-zirconium alloy and a preparation method thereof, and obtains a novel microstructure: a composite structure of nano-twins, micro-crystals and nano-precipitates. The copper alloy with this structure has a tensile strength of 750-850 MPa and a conductivity of 80%-90% IACS. However, this preparation method is to perform equal channel deformation (ECAP) treatment in a liquid nitrogen environment, which is not suitable for industrial mass production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of a high-strength and high-conductivity copper-chromium-zirconium alloy and a method for regulating its structure and properties. The provided copper-chromium-zirconium alloy preparation method has a short process flow, and can realize continuous large-scale, high-quality and stable production; the provided copper-chromium-zirconium alloy microstructure and property regulation method can improve the morphology and distribution of the primary phase, and induce nano-layered The structure and substructure greatly improve the strength of the alloy, reaching the "double 70" standard.

In the first aspect, the application provides a method for preparing a high-strength and high-conductivity copper-chromium-zirconium alloy, which is realized by the following technical solutions:

A high-strength and high-conductivity copper-chromium-zirconium alloy is composed of the following elements: chromium: 0.8-1.2 wt.%; zirconium: 0.1-0.5 wt.%; the rest is copper and its inevitable impurities, and the mass sum of the content of each component is 100%.

Preferably, in terms of mass percentage, the high-strength and high-conductivity copper-chromium-zirconium alloy includes: chromium: 0.8-1.0 wt.%; zirconium: 0.1-0.2 wt.%; the rest are copper and its inevitable impurities, and the content of each component is The sum of the masses is 100%.

A preparation method of high-strength and high-conductivity copper-chromium-zirconium alloy, comprising the following steps:

(1) Melt the electrolytic copper, Cu-Cr master alloy and Cu-Zr master alloy according to the composition ratio in the vacuum induction melting furnace under the protection of inert gas atmosphere, and transfer to the holding furnace when the copper liquid temperature is 1260±10℃ Let it stand in the middle, and start the four-stream horizontal continuous casting traction when the temperature of the copper liquid at the entrance of the mold is 1100±10℃;

(2) The copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a total deformation of 30% to 50%;

(3) controlling the primary phase of the copper-chromium-zirconium alloy treated in step (2), the treatment method is water quenching immediately after solution treatment at 800-1000° C. for 30-60 min;

(4) subjecting the solution-treated copper-chromium-zirconium alloy to the second cold deformation with a total deformation of more than 95%;

(5) carrying out aging treatment on the copper-chromium-zirconium alloy obtained in the previous step, the aging treatment temperature is 400～500℃, and the aging treatment time is 10～600min;

(6) subjecting the aged copper-chromium-zirconium alloy to the third cold deformation with a total deformation amount of 40% to 60%.

Preferably, the crystallizer in the step (1) is a special crystallizer, and the crystallizer is made of boron nitride and beryllium copper, wherein the boron nitride end directly contacts the copper alloy liquid, and the beryllium copper end is connected to the cooling water copper jacket. The connection method of boron nitride and beryllium copper is screw connection or high temperature glue connection. The crystallizer overcomes the shortcomings of low strength and wear resistance of the traditional graphite crystallizer, and at the same time combines the advantages of boron nitride with high temperature resistance, fast thermal conductivity, self-lubrication, good elasticity and high strength of beryllium copper, and comprehensively improves the Cu-Cr-Zr alloy. The surface quality of the billet.

Preferably, the pulling process of vacuum horizontal continuous casting in the step (1) is as follows: pulling pitch: 2～4mm; pulling speed: 1～6mm/s; stopping time: 0～0.5s; 0.2s.

Preferably, the total deformation amount of the first cold deformation in the step (2) is 40% to 50%.

Preferably, the solution treatment temperature of the step (3) is 900-950°C, more preferably 950°C.

Preferably, the aging treatment temperature of the step (5) is 460-500°C, more preferably 500°C.

Preferably, the total deformation amount of the third cold deformation in the step (6) is 50-60%, more preferably 50%.

In the second aspect, the method for regulating the microstructure and properties of a copper-chromium-zirconium alloy provided by the present application is a combination of the above-mentioned deformation heat treatment processes. After the solution treatment, the needle-shaped primary phase can be regulated into a spherical shape; drawing and aging with large deformation amount Treatment induces the generation of nanolayered structures and substructures. The structure in the alloy includes matrix phase, primary phase and precipitation phase: among them, the matrix phase is nano-grain with nano-layered structure, including deformation twins and substructures of more than 50%; more than 90% of the primary phase is spherical; precipitation The phases are mainly Cr phases with a diameter of less than 10 nm, and Cu ₄ Zr and Cu ₅ Zr are equal.

Preferably, the size of the spherical primary phase is 100-200 nm.

Preferably, more than 80% of the spherical primary phase is distributed at the grain boundary.

Preferably, the width of the nano-layered structure is not greater than 200 nm.

Preferably, the substructure ratio is above 70%.

To sum up, the present application has the following beneficial effects:

1. The vacuum horizontal continuous casting method provided by the present invention can ensure the uniformity of the composition in the length direction, and realize the continuous mass production of copper-chromium-zirconium alloy in a short process with high quality by optimizing the mold and adjusting the parameters of the casting process. The subsequent primary phase and tissue properties control methods are simple and can be quickly applied to industrial production.

2. The method for regulating and controlling the morphology and distribution of the primary phase provided by the present invention is carried out when the alloy undergoes deformation heat treatment. Compared with the regulation during casting, the method provided by the present invention is simpler and safer, and can detect the effect of regulation in time. At the same time, the structure of the ingot with poor as-cast structure can be adjusted to improve the yield of the product. After adjustment and refinement, the shape of the primary phase changes from dendritic to spherical, and the pin is rolled at the grain boundary, and will not deform and grow during subsequent processing and heat treatment. Resistance, grain refinement, and synergistic effect with the precipitation phase, ensuring the high temperature stability of the nano-layered structure and substructure, and significantly improving the comprehensive properties of the copper-chromium-zirconium alloy.

3. The copper-chromium-zirconium alloy of the present invention obtains a new type of nano-structure: nano-layered structure, nano-primary phase, nano-precipitate phase and nano-level substructure. Due to its unique structure, the tensile strength can reach more than 800MPa, the electrical conductivity can be maintained above 75% IACS, and the elongation can reach more than 10%, which meets the requirements of high strength and high conductivity and bending process of copper-chromium-zirconium alloy.

4. The nano-layered structure in the microstructure of the copper-chromium-zirconium alloy of the present invention has high temperature stability, which ensures that the alloy has high strength after aging and drawing treatment.

5. The microstructure of the copper-chromium-zirconium alloy of the present invention has at least more than 70% substructure, and the substructure greatly improves the tensile strength of the copper-chromium-zirconium alloy.

Description of drawings

Figure 1 is the SEM micrographs of the primary phase in the copper-chromium-zirconium alloy at different stages of deformation heat treatment. (Fig. 1(a) and Fig. 1(b) are the SEM images of the as-cast state, Fig. 1(c) is the SEM image of the first cold deformation, and Fig. 1(d) is the SEM image of the solid solution state. , Figure 1(e) is the SEM image of the aging state, and Figure 1(f) is the SEM image of the third cold deformation).

Figure 2 shows the XRD patterns of the as-cast, first cold-deformed and solid-solution state of the copper-chromium-zirconium alloy.

Figure 3 is the stress-strain curve of copper-chromium-zirconium alloy.

4 is a distribution diagram of the recrystallized structure, deformed structure and substructure in the copper-chromium-zirconium alloy of Example 1.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below with reference to examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limit the claims of the present invention.

(1) Preparation method of copper-chromium-zirconium alloy

The present application provides a copper-chromium-zirconium alloy and a preparation method thereof, including vacuum smelting, vacuum horizontal continuous casting, first cold deformation, solid solution treatment, second cold deformation, aging treatment and third cooling in sequence. deformed.

In the present invention, the raw materials for vacuum smelting include electrolytic copper, Cu-10wt.%Cr master alloy, and Cu-40wt.%Zr master alloy. The alloy components are preferably (by mass percentage): 0.8-1.0 wt.%; Zr: 0.1-0.2 wt.%; the rest are Cu and its inevitable impurities, and the total mass of each component content is 100%.

The present invention does not specifically limit the specific source of the alloy raw material and the composition of the master alloy, and a commercially available product well known to those skilled in the art can be used. The present invention can reduce the content of impurities in the copper-chromium-zirconium alloy by using the above-mentioned alloy raw materials, and further improve the performance of the alloy.

In the present invention, the temperature of the vacuum melting is preferably 1260±10°C. If the temperature is lower than 1250°C, on the one hand, it is not conducive to the escape of impurity gas in the melt, and on the other hand, when the melt is transferred to the holding furnace, it is easy to block the gate or stick to the wall of the launder. Before the smelting heating starts, the smelting furnace cavity is evacuated to below 5×10 ^-2 Pa, then filled with 50000Pa inert gas, and smelting is carried out under the protection of inert gas atmosphere.

In the present invention, the inert gas is nitrogen or argon with a purity greater than 99.99%.

In the present invention, the mold used in vacuum horizontal continuous casting is preferably a boron nitride and beryllium copper combined mold, wherein the boron nitride end directly contacts the copper alloy liquid, and the beryllium copper end is connected to the cooling water copper jacket. The connection method of boron nitride and beryllium copper is screw connection or high temperature glue connection. Boron nitride has good lubricity, wear resistance and high temperature resistance, which can ensure good surface quality of copper-chromium-zirconium casting billets; beryllium copper has high strength and high elasticity, which can increase the service life of the mold. If a mold of other materials, such as graphite, is used, it is easy to cause scratches on the surface, and the service life is also shorter.

In the present invention, the pulling process of vacuum horizontal continuous casting is preferably: pulling pitch: 2-4 mm; pulling speed: 1-6 mm/s; stopping time: 0-0.5 s; reverse thrust time: 0-0.2 s.

If the pulling speed is too fast and the surface temperature is high, the surface of the slab is prone to oxidation and blackening, and hot cracks or even fractures will occur. If the pulling speed is too slow, the efficiency is too low and the front end of the strand may solidify and damage the mold. The four continuous casting parameters of traction pitch, traction speed, stop time and reverse thrust time are not isolated, and any parameter change may affect the surface quality of the slab.

In the present invention, the alloy must be subjected to the first cold deformation before solution treatment. The first cold deformation can bring deformation energy storage, provide the driving force for recrystallization nucleation, and promote recrystallization and the excess phase to dissolve back into the matrix. At the same time, the deformation energy storage brought by cold deformation can accelerate the regulation process of the primary phase. If the cold deformation is not performed before the solution treatment, the solid solution effect will be insufficient, and a sufficient number of nano-scale precipitates cannot be precipitated to strengthen the matrix in the subsequent aging precipitation process. At the same time, the morphology and distribution of the primary phase are not fully controlled. Through the first cold deformation treatment in the invention, the coarse grains in the casting state can also be broken, the cracks can be healed significantly, the casting defects can be reduced or eliminated, the as-cast structure can be transformed into a deformed structure, and the processing performance of the alloy can be improved.

In the present invention, the total deformation amount of the first cold deformation is preferably 40% to 50%. The present invention has no special limitation on the deformation pass and the processing rate of a single pass, which can be determined according to the technical common sense of those skilled in the art.

In the present invention, the solution treatment temperature is preferably 900 to 950°C, and more preferably 950°C. If the solid solution temperature is lower than 900°C, the solid solution will be incomplete and the recrystallization will be insufficient, which will affect the subsequent processing and aging precipitation strengthening effect. If the solution temperature is higher than 950°C, the grains tend to grow, which is not conducive to processing.

In the present invention, the total deformation amount of the second cold deformation is preferably ≥95%. Large deformation deformation can induce the generation of nano-layered structures. The present invention has no special limitation on the deformation pass and the processing rate of a single pass, which can be determined according to the technical common sense of those skilled in the art. If the total deformation of the second cold deformation is less than 95%, sufficient nano-layered structure cannot be produced, and the dislocation density cannot meet the requirements, which affects the regulation of substructure in the subsequent processing.

In the present invention, the aging treatment temperature is 460 to 500°C, more preferably 500°C. The aging treatment at 500℃ can shorten the aging time and achieve the purpose of energy saving and emission reduction; on the other hand, the high temperature aging stimulates the dislocation activity, and the dislocation activity is relatively large. Dislocations tend to aggregate and tangle locally, forming dislocation clusters, thereby inducing the generation of substructures. The present invention can improve the strength and electrical conductivity of the alloy through the aging treatment, and simultaneously reduce the internal stress.

In the present invention, the total deformation amount of the third cold deformation is 50 to 60%, more preferably 50%. Cold deformation after aging can promote the formation of substructures. The present invention has no special limitation on the deformation pass and the processing rate of a single pass, which can be determined according to the technical common sense of those skilled in the art.

In the present invention, the cold deformation includes common metal processing techniques such as drawing and rolling.

In the present invention, a multi-stage deformation heat treatment process is adopted, including three cold deformations and two heat treatments. Compared with the traditional copper alloy processing method, the method provided by the present invention has the advantage that the casting billet adopts the method of vacuum horizontal continuous casting, which ensures the composition stability and surface quality of the Cu-Cr-Zr alloy casting billet. The combination of the multi-stage deformation heat treatment process, on the one hand, regulates the morphology of the primary phase, and modulates the needle-like primary phase that damages the performance into a spherical shape that improves the performance. The layered structure and aging treatment produce substructures, and the synergistic effect between each process forms the combined microstructure of nano-layered structure, nano-primary phase, nano-precipitation phase and nano-scale sub-structure, which improves the Cu-Cr-Zr alloy. comprehensive performance.

(2) Microstructure and properties control method of copper-chromium-zirconium alloy

The control method of microstructure and properties of copper-chromium-zirconium alloy is a combined process of deformation heat treatment process. After solution treatment, the needle-like primary phase is regulated into spherical shape; drawing with large deformation amount and aging treatment induce nano-layered structure and substructure. production. After the above deformation and heat treatment, a unique new nanostructure structure is obtained in the copper-chromium-zirconium alloy matrix: nano-layered structure, nano-primary phase, nano-precipitate phase and nano-scale substructure. Among them, the matrix phase is nanocrystalline grains with nano-layered structure, including deformation twins and more than 50% of substructures; more than 90% of the primary phase morphology is spherical. The primary phase and the precipitation phase are pinched at the grain boundary, which ensures the high temperature stability of the nanolayered structure.

In the present invention, the size of the spherical primary phase is 100-200 nm, and if the size of the spherical precipitation phase is larger than 200 nm, it is easy to cause crack initiation and affect the properties of the alloy.

In the present invention, more than 80% of the spherical primary phase is distributed at the grain boundary, thereby ensuring the refining effect during solid solution and the effect of increasing the deformation resistance in the subsequent deformation process.

In the present invention, the width of the nano-layered structure is not greater than 200 nm.

In the present invention, substructure refers to a crystal that is deformed or deformed by cold working and is not completely recovered, and the crystal grains whose original crystallographic orientation is basically the same will be refined into small crystal blocks with slightly different orientations (a few minutes to a few degrees). The Cu-Cr-Zr alloy forms a cellular substructure after cold plastic deformation. In the subsequent recovery process, the dislocations in the cell wall gradually form a dislocation network of low energy states, and the cell wall becomes clearer and becomes a subgrain boundary. Substructures can be identified by EBSD calibration.

In the present invention, the substructure ratio is 70% or more.

The specific nano-scale mixed structure makes the copper-chromium-zirconium alloy have the characteristics of high strength and high conductivity, and has excellent comprehensive properties.

In fact, each process of the above-mentioned preparation method does not work in isolation, and its influence is mutual, and the adjustment of any one of the process parameters will bring changes to the properties of the alloy. Each process has its own independent function, but after these processes are combined with each other, the processes stimulate each other and promote each other, and the synergistic effect is very obvious, which significantly improves the processability, mechanical properties and physical properties of copper-chromium-zirconium alloys.

The present invention does not limit the processing equipment and process parameters not mentioned in the above method, and the processing equipment and process parameters well known to those skilled in the art can be used.

In order to further understand the present invention, a method for preparing a high-strength and high-conductivity copper-chromium-zirconium alloy provided by the present invention and a method for regulating its structure and properties are described in detail below with reference to the examples. The protection scope of the present invention is not limited by the following examples.

Example 1

(1) Vacuum horizontal continuous casting: Melt the copper-chromium-zirconium alloy with the ratio of Cr: 0.8wt.%, Zr: 0.2wt.% and the balance of copper in a vacuum induction melting furnace. When the temperature of the copper liquid reaches 1270 °C Transfer to the holding furnace and let it stand, cool down to the temperature of the copper liquid at the entrance of the mold is 1110 ℃, and start the four-stream horizontal continuous casting traction; the traction process is: the traction pitch is 3mm, the traction speed is 1mm/s, the stop time is 0.5s, and the reverse Push time 0.2s.

(2) The first cold deformation: the copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a total deformation of 50%;

(3) Primary phase control: The primary phase control of the copper-chromium-zirconium alloy after the first cold deformation treatment is performed by water quenching immediately after solution treatment at 950 °C for 60 minutes;

(4) The second cold deformation: the copper-chromium-zirconium alloy after solution treatment is subjected to the second cold deformation with a deformation amount of 98.5%;

(5) aging treatment: the copper-chromium-zirconium alloy obtained in the previous step is subjected to aging treatment, the aging treatment temperature is 500 ° C, and the aging treatment time is 30 minutes;

(6) The third cold deformation: the copper-chromium-zirconium alloy after the aging treatment is subjected to the third cold deformation with a deformation amount of 50%.

Characterized by SEM, EBSD and TEM, the primary phase is transformed from needle-like to spherical, inherited during the deformation heat treatment process, and more than 80% are distributed in the grain boundary; the alloy is mainly composed of nano-layered structure and sub-structure, including a certain amount of primary phase. phase and precipitation phase. The average width of the nano-layered structures is 120 nm, and the proportion of substructures is 64.5%. The tensile strength is 730MPa, and the electrical conductivity is 78% IACS.

Example 2

(1) Vacuum horizontal continuous casting: Melt the copper-chromium-zirconium alloy with the ratio of Cr: 0.8wt.%, Zr: 0.1wt.%, and the balance of copper in a vacuum induction melting furnace. When the temperature of the copper liquid reaches 1250 ℃ Transfer to the holding furnace and let it stand, cool down to the temperature of the copper liquid at the entrance of the mold is 1090 ℃, and start the four-stream horizontal continuous casting traction; the traction process is: traction pitch 4mm, traction speed 6mm/s, stop time 0s, reverse push time 0s.

(2) The first cold deformation: the copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a total deformation of 40%;

(3) Primary phase control: The primary phase control of the copper-chromium-zirconium alloy after the first cold deformation treatment is performed by water quenching immediately after solution treatment at 950 °C for 30 minutes;

(4) The second cold deformation: the copper-chromium-zirconium alloy after solution treatment is subjected to the second cold deformation with a deformation amount of 95%;

(5) aging treatment: the copper-chromium-zirconium alloy obtained in the previous step is subjected to aging treatment, the aging treatment temperature is 500°C, and the aging treatment time is 60min;

(6) The third cold deformation: the copper-chromium-zirconium alloy after the aging treatment is subjected to the third cold deformation with a deformation amount of 50%.

Characterized by SEM, EBSD and TEM, the primary phase is transformed from needle-like to spherical, inherited during the deformation heat treatment process, and more than 80% are distributed in the grain boundary; the alloy is mainly composed of nano-layered structure and sub-structure, including a certain amount of primary phase. phase and precipitation phase. The average width of the nano-layered structures is 116 nm, and the proportion of substructures is 53.2%. After mechanical and electrical performance tests, the tensile strength reaches 749MPa, and the electrical conductivity is 81% IACS.

Example 3

(1) Vacuum horizontal continuous casting: Melt the copper-chromium-zirconium alloy with the ratio of Cr: 0.8wt.%, Zr: 0.1wt.% and the balance of copper in a vacuum induction melting furnace. When the temperature of the copper liquid reaches 1260 °C Transfer to the holding furnace and let it stand, cool down to the temperature of the copper liquid at the entrance of the mold is 1100 ℃, and start the four-stream horizontal continuous casting traction; the traction process is: the traction pitch is 2mm, the traction speed is 5mm/s, the stop time is 0.5s, and the reverse Push time 0.1s.

(2) The first cold deformation: the copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a total deformation of 43.75%;

(3) Primary phase control: The primary phase control of the copper-chromium-zirconium alloy after the first cold deformation treatment is performed by water quenching immediately after solution treatment at 950 °C for 60 minutes;

(4) The second cold deformation: the copper-chromium-zirconium alloy after solution treatment is subjected to the second cold deformation with a deformation amount of 97.2%;

(5) aging treatment: the copper-chromium-zirconium alloy obtained in the previous step is subjected to aging treatment, the aging treatment temperature is 500 ° C, and the aging treatment time is 30 minutes;

(6) The third cold deformation: the copper-chromium-zirconium alloy after the aging treatment is subjected to the third cold deformation with a deformation amount of 50%.

Characterized by SEM, EBSD and TEM, the primary phase is transformed from needle-like to spherical, inherited during the deformation heat treatment process, and more than 80% are distributed in the grain boundary; the alloy is mainly composed of nano-layered structure and sub-structure, including a certain amount of primary phase. phase and precipitation phase. The average width of the nano-layered structures is 124 nm, and the proportion of substructures is 74.2%. The tensile strength is 803MPa, and the electrical conductivity is 76%IACS.

Example 4 (comparative example)

(1) Vacuum horizontal continuous casting: Melt the copper-chromium-zirconium alloy with the ratio of Cr: 0.8wt.%, Zr: 0.1wt.% and the balance of copper in a vacuum induction melting furnace. When the temperature of the copper liquid reaches 1260 °C Transfer to the holding furnace and let it stand, cool down to the temperature of the copper liquid at the entrance of the mold is 1100 ℃, and start the four-stream horizontal continuous casting traction; the traction process is: the traction pitch is 2mm, the traction speed is 5mm/s, the stop time is 0.5s, and the reverse Push time 0.1s.

(2) The first cold deformation: the copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a total deformation of 45%;

(3) Primary phase control: The primary phase control of the copper-chromium-zirconium alloy after the first cold deformation treatment is performed by water quenching immediately after solution treatment at 900 °C for 60 minutes;

(4) The second cold deformation: the copper-chromium-zirconium alloy after solution treatment is subjected to the second cold deformation with a deformation amount of 95%;

(5) aging treatment: the copper-chromium-zirconium alloy obtained in the previous step is subjected to aging treatment, the aging treatment temperature is 450 ° C, and the aging treatment time is 120 min;

(6) The third cold deformation: the copper-chromium-zirconium alloy after the aging treatment is subjected to the third cold deformation with a deformation amount of 50%.

Characterized by SEM, EBSD and TEM, the primary phase is transformed from needle-like to spherical, inherited during the deformation heat treatment process, and more than 80% are distributed in the grain boundary; the alloy is mainly composed of nano-layered structure and sub-structure, including a certain amount of primary phase. phase and precipitation phase. The average width of the nano-layered structures is 130 nm, and the proportion of substructures is 42.3%. The tensile strength is 648MPa and the electrical conductivity is 80% IACS after the mechanical properties and electrical properties test.

The as-cast tensile strength of the Cu-Cr-Zr alloy in Example 1 is 256 MPa, and the electrical conductivity is 38% IACS. After multi-stage plastic deformation and heat treatment process and control of primary equal microstructure, the tensile strength is increased to 730MPa, which is 474MPa higher than that of the as-cast state, which is 2.85 times that of the as-cast state, and the electrical conductivity is also increased from 38%. The IACS was increased to 78% IACS, and the improvement effect was significant. It shows that the multi-stage deformation heat treatment process combined with the primary equal microstructure control method has good innovation and breakthrough. Compared with Example 1, Example 2 shortens the solution time (from 60min to 30min) and prolongs the aging time (from 30min to 60min), although the proportion of substructure decreases, but the width of the nano-layered structure decreases. , the aging time is longer and the precipitation is more sufficient, so the electrical conductivity will be slightly increased, and the tensile strength will also increase by 19MPa. In order to further improve the tensile strength of Cu-Cr-Zr alloy, the deformation heat treatment process was adjusted again. In Example 3, the primary phase regulation time (solution treatment time) was 60 min, the primary phase regulation was more sufficient, and at the same time, more substructures were induced in the subsequent deformation heat treatment process, and the proportion of substructures reached 74.2%. With the effect of sub-structural strengthening, the tensile strength is significantly improved, and the tensile strength exceeds 800MPa. Example 4 is a comparative example. In the comparative example, the control temperature of the primary phase is lower, and the proportion of the substructure is only 42.3%, so the strength is only 648MPa. This also means that each process of the above-mentioned preparation method does not work in isolation, and its influence is mutual, and the adjustment of any one of the process parameters will bring changes to the properties of the alloy. Each process has its own independent function, but after these processes are combined with each other, the processes stimulate each other and promote each other, and the synergistic effect is very obvious, which significantly improves the processability, mechanical properties and physical properties of copper-chromium-zirconium alloys.

Figure 1 is the SEM micrographs of the primary phase in the copper-chromium-zirconium alloy at different stages of deformation heat treatment. It can be seen from the figure that the as-cast microstructure of the Cu-Cr-Zr alloy in vacuum horizontal continuous casting contains a large number of needle-like primary phases. Spherical, and basically distributed in grain boundaries. In the subsequent cold deformation and aging process, the spherical primary phase will not deform and disappear, but is inherited, increasing the deformation resistance, hindering the movement of grain boundaries, thereby refining the grains, and ensuring the high temperature stability of the nano-layered structure. sex.

Fig. 2 XRD patterns of copper-chromium-zirconium alloy as-cast, first cold-deformed and solid-solution state. It can be found that in addition to the Cu diffraction peak, the Cr diffraction peak of the (110) crystal plane also appears in the XRD curve. Although the content of chromium element in the copper-chromium-zirconium alloy is only about 1 wt.%, the presence of Cr element is still detected, indicating that the primary Cr content is relatively large.

FIG. 3 is the stress-strain curves of the copper-chromium-zirconium alloys of Examples 1-3 and Comparative Examples. After the primary phase control, the tensile strength of the alloy is significantly improved, exceeding 700MPa, and the highest is more than 800MPa.

4 is a distribution diagram of the recrystallized structure, deformed structure and substructure in the copper-chromium-zirconium alloy of Example 1. Among them, the proportion of substructure exceeds 70%, which greatly improves the performance of the alloy.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. a copper-chromium-zirconium alloy preparation method, is characterized in that, described preparation method comprises the steps: (1) Melt electrolytic copper, Cu-Cr, Cu-Zr master alloy in a vacuum induction melting furnace under the protection of argon atmosphere, transfer the copper liquid temperature to 1260 ± 10 °C and place it in a holding furnace, and wait for the crystallizer to stand. When the temperature of the inlet copper liquid is 1100±10℃, the four-stream horizontal continuous casting starts to draw the copper-chromium-zirconium alloy billet; (2) The copper-chromium-zirconium alloy casting billet is subjected to the first cold deformation with a deformation amount of 30% to 50%; (3) water quenching immediately after the copper-chromium-zirconium alloy treated in step (2) is solution-treated at 800-1000° C. for 30-60 minutes; (4) subjecting the solution-treated copper-chromium-zirconium alloy to the second cold deformation with a deformation amount of more than 95%; (5) carrying out aging treatment on the copper-chromium-zirconium alloy obtained in the previous step, the aging treatment temperature is 400～500℃, and the aging treatment time is 10～600min; (6) subjecting the aged copper-chromium-zirconium alloy to the third cold deformation with a deformation amount of 40% to 60%. 2. The preparation method according to claim 1, wherein the copper-chromium-zirconium alloy is composed of the following elements: chromium: 0.8-1.0wt.%; zirconium: 0.1-0.2wt.%; To avoid impurities, the mass sum of the content of each component is 100%. 3. preparation method as claimed in claim 1 is characterized in that: the crystallizer material that step (1) adopts is boron nitride and beryllium copper, wherein boron nitride end directly contacts copper alloy liquid, and beryllium copper end is connected with cooling water Copper sets. 4. preparation method as claimed in claim 1 is characterized in that: the vacuum horizontal continuous casting pulling process in step (1) is: pulling pitch: 2～4mm; Pulling speed: 1～6mm/s; Stop time: 0～0.5s; Reverse push time: 0～0.2s. 5 . The preparation method according to claim 1 , wherein the structure in the alloy includes a matrix phase, a primary phase and a precipitation phase, wherein the matrix phase is nano-grains and sub-structures of nano-layered structure. 6 . 6 . The preparation method according to claim 5 , wherein the size of the spherical primary phase is 100-200 nm, accounting for 90%, and more than 80% is distributed at the grain boundary. 7 . 7 . The preparation method according to claim 5 , wherein the width of the nano-layered structure is not greater than 200 nm. 8 . 8. The preparation method according to claim 5, wherein the substructure ratio is more than 70%. 9 . The preparation method according to claim 1 , wherein the tensile strength of the copper-chromium-zirconium alloy exceeds 700 MPa, and the electrical conductivity is above 70% IACS. 10 . 10 . The preparation method according to claim 1 , wherein the copper-chromium-zirconium alloy has a tensile strength of more than 800 MPa and an electrical conductivity of more than 75% IACS. 11 .

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