CN115074564B - Preparation method of high-strength high-conductivity copper-chromium-zirconium alloy - Google Patents
Preparation method of high-strength high-conductivity copper-chromium-zirconium alloy Download PDFInfo
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Abstract
The application discloses a preparation method of a high-strength high-conductivity copper-chromium-zirconium alloy, which comprises the following components: chromium: 0.8 to 1.2wt.%; zirconium: 0.1 to 0.5wt.%; the balance copper and unavoidable impurities, and the preparation method comprises multi-stage cold deformation and heat treatment, wherein the multi-stage cold deformation and heat treatment sequentially comprise vacuum horizontal continuous casting, first cold deformation, solution treatment, second cold deformation, aging treatment and third cold deformation. The needle-shaped primary phase can be regulated and controlled to be spherical by the method; the obtained copper-chromium-zirconium alloy has a large number of spherical primary phases which have a nano lamellar structure, a nano substructure and a nano-structure and are genetically distributed on grain boundaries. The tensile strength of the copper-chromium-zirconium alloy with the structure reaches more than 700MPa, the highest tensile strength can exceed 800MPa, the conductivity is kept at more than 75% IACS, and the copper-chromium-zirconium alloy can be rapidly suitable for industrial continuous mass production.
Description
Technical Field
The invention belongs to the technical field of copper alloy, and particularly relates to a preparation method of a high-strength high-conductivity copper-chromium-zirconium alloy.
Background
In recent years, along with the gradual increase of the speed per hour of a high-speed railway, higher requirements are put forward on the strength and the conductivity of a copper alloy contact line; on the other hand, electronic and electrical equipment, unmanned aerial vehicles, and the like are being miniaturized and thinned, and copper alloys are required to have high strength and high conductivity, and also to satisfy the requirements of small wire diameter (thin thickness) and good stability. The high-performance copper alloy is developed towards the double 70 alloy, namely, the tensile strength is not less than 700MPa, and the electric conductivity is not less than 70% IACS. The tensile strength and the conductivity of the copper-chromium-zirconium alloy are expected to meet the requirements, but the uniformity of the components is unstable, few domestic enterprises can stably produce large-length and large-coil-weight cast ingots, and the current urgent need is to break through the high-strength and high-conductivity copper-chromium-zirconium alloy large-coil-weight continuous key blank making technology. The continuous casting with upward drawing is an optional method, and enterprises carry out production, but the continuous casting with upward drawing still has the problems of low purity of alloy melt, inconsistent head and tail components, uneven surface quality and the like, and the continuous casting with vacuum level can solve the problems, firstly keep raw materials clean, ensure that the melt can not oxidize and slag under vacuum, and ensure the surface quality of products by gas protection at the outlet of a crystallizer.
In the casting process of copper-chromium-zirconium alloy, coarse chromium-rich primary phases are easy to appear. Besides the precipitation strengthening phase, the distribution and morphology characteristics of the primary phase in the copper-chromium-zirconium alloy also have important influence on the performance of the alloy. When the morphology of the primary phase is long-strip-shaped and regular prismatic, cracks are easy to grow and propagate, and the mechanical properties of the alloy are obviously affected; when the primary phase is in a tiny spherical shape, the alloy strength can be obviously improved, and the comprehensive mechanical property of the alloy can be improved. The primary phase control mostly adjusts casting parameters during solidification, thereby controlling morphology and size of the primary phase, such as controlling cooling rate. The morphology and the distribution of the primary phase can be regulated and controlled in the subsequent thermomechanical treatment process.
Patent document publication No. CN104342575B discloses a method for producing a copper-chromium-zirconium continuous casting slab with a large length and a large cross section by vacuum melting and vacuum horizontal continuous casting. However, the tensile strength is only 620MPa at most, and the method has a gap from the current target of 'double 70' (the tensile strength is more than or equal to 700MPa, and the conductivity is more than or equal to 70% IACS).
Patent document with publication number of CN110055479B discloses an 800 MPa-level high-conductivity copper-chromium-zirconium alloy and a preparation method thereof, and a novel microstructure is obtained: a composite structure of nanometer twin crystals, microcrystals and nanometer precipitates. The tensile strength of the copper alloy with the structure reaches 750-850 MPa, and the conductivity is 80-90% IACS. However, the preparation method is characterized in that the equal channel deformation (ECAP) treatment is carried out in a liquid nitrogen environment, and is not suitable for industrialized mass production.
Disclosure of Invention
The invention aims to provide a preparation method of a high-strength high-conductivity copper-chromium-zirconium alloy and a structure property regulation mode thereof. The preparation method of the copper-chromium-zirconium alloy has short flow, and can realize continuous mass high-quality stable production; the provided mode for regulating and controlling the tissue performance of the copper-chromium-zirconium alloy can improve the morphology and distribution of a primary phase, induce the generation of a nano layered structure and a sub-structure, greatly improve the strength of the alloy and reach the standard of double 70.
In a first aspect, the present application provides a preparation method of a high-strength and high-conductivity copper-chromium-zirconium alloy, which is implemented by adopting the following technical scheme:
a high-strength high-conductivity copper-chromium-zirconium alloy consists of the following elements: chromium: 0.8 to 1.2wt.%; zirconium: 0.1 to 0.5wt.%; the balance of copper and unavoidable impurities, and the total mass of the contents of all components is 100%.
Preferably, the high-strength high-conductivity copper-chromium-zirconium alloy comprises the following components in percentage by mass: chromium: 0.8 to 1.0wt.%; zirconium: 0.1 to 0.2wt.%; the balance of copper and unavoidable impurities, and the total mass of the contents of all components is 100%.
The preparation method of the high-strength high-conductivity copper-chromium-zirconium alloy comprises the following steps:
(1) Melting electrolytic copper, cu-Cr intermediate alloy and Cu-Zr intermediate alloy according to the composition ratio in a vacuum induction melting furnace under the protection of inert gas atmosphere, transferring the molten copper to a heat preservation furnace for standing when the temperature of the molten copper is 1260+/-10 ℃, and starting four-flow horizontal continuous casting traction when the temperature of the molten copper at an inlet of a crystallizer is 1100+/-10 ℃;
(2) Performing first cold deformation of the copper-chromium-zirconium alloy casting blank with the total deformation of 30% -50%;
(3) Primary phase regulation and control are carried out on the copper-chromium-zirconium alloy treated in the step (2), the treatment mode is that water quenching is immediately carried out after solution treatment for 30-60 min at 800-1000 ℃;
(4) Carrying out second cold deformation with the total deformation of more than 95% on the copper-chromium-zirconium alloy subjected to solution treatment;
(5) Aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 400-500 ℃, and the aging time is 10-600 min;
(6) And (3) performing third cold deformation with the total deformation of 40% -60% on the copper-chromium-zirconium alloy after aging treatment.
Preferably, the crystallizer in the step (1) is a special crystallizer, the material of the crystallizer is boron nitride and beryllium copper, wherein the boron nitride end directly contacts copper alloy liquid, and the beryllium copper end is connected with a cooling water copper sleeve. The connection mode of the boron nitride and the beryllium copper is threaded connection or high-temperature glue connection. The crystallizer overcomes the defects of low strength and wear resistance of the traditional graphite crystallizer, combines the advantages of high temperature resistance, high heat conduction speed, good self-lubrication and beryllium copper elasticity, high strength and the like of the boron nitride, and comprehensively improves the surface quality of the Cu-Cr-Zr alloy casting blank.
Preferably, the vacuum horizontal continuous casting traction process in the step (1) is as follows: traction pitch: 2-4 mm; traction speed: 1-6 mm/s; stop time: 0 to 0.5s; back-pushing time: 0 to 0.2s.
Preferably, the total deformation amount of the first cold deformation in the step (2) is 40% -50%.
Preferably, the solution treatment temperature in the step (3) is 900 to 950 ℃, more preferably 950 ℃.
Preferably, the aging temperature of step (5) is 460 to 500 ℃, more preferably 500 ℃.
Preferably, the total deformation amount of the third cold deformation in the step (6) is 50 to 60%, more preferably 50%.
In a second aspect, the method for regulating and controlling the structural performance of the copper-chromium-zirconium alloy is as followsAfter the combination of the thermomechanical treatment processes is subjected to solution treatment, the needle-shaped primary phase can be regulated and controlled to be spherical; drawing and aging treatment with large deformation can induce the generation of nano lamellar structures and substructures. The structure in the alloy comprises a matrix phase, a primary phase and a precipitated phase: wherein the matrix phase is nano crystal grains with nano lamellar structure and comprises deformation twin crystal and more than 50% of substructure; more than 90% of the primary phase is spherical; the precipitated phase is mainly Cr phase and Cu phase with diameter less than 10nm 4 Zr and Cu 5 Zr is equal.
Preferably, the size of the spherical primary phase is 100 to 200nm.
Preferably, 80% or more of the spherical primary phase is distributed at the grain boundaries.
Preferably, the nanolayered structure has a width of no more than 200nm.
Preferably, the proportion of substructures is more than 70%.
In summary, the present application has the following beneficial effects:
1. the vacuum horizontal continuous casting method provided by the invention can ensure the uniformity of components in the length direction, and realizes high-quality short-flow continuous large-batch preparation of copper-chromium-zirconium alloy through crystallizer optimization and casting process parameter adjustment. The subsequent primary phase and tissue performance regulation and control method is simple and can be rapidly applied to industrial production.
2. Compared with the regulation and control during casting, the method provided by the invention is simpler and safer, can timely detect the regulation and control effect, can carry out structure adjustment on cast ingots with bad cast structure, and improves the yield of products. Through regulation and refinement, the shape of the primary phase is changed from dendrite shape into sphere shape, and is nailed and rolled on the grain boundary, deformation and growth can not occur in the subsequent processing and heat treatment processes, and the composite material has genetic characteristics, can be used as a nucleation point, improves deformation resistance, refines grains, and has synergistic effect with a precipitated phase, thereby ensuring the high-temperature stability of a nano layered structure and a substructure, and remarkably improving the comprehensive performance of the copper-chromium-zirconium alloy.
3. The copper-chromium-zirconium alloy of the invention obtains a novel nano-structure: a nano lamellar structure, a nano primary phase, a nano precipitated phase and a nano level substructure. Because of the unique tissue structure, the tensile strength can reach more than 800MPa, the conductivity can be kept at more than 75% IACS, the elongation can reach more than 10%, and the requirements of the copper-chromium-zirconium alloy on high-strength high-conductivity performance and bending process are met.
4. The nano layered structure in the copper-chromium-zirconium alloy structure has high-temperature stability, and ensures that the alloy has high strength after aging and drawing treatment.
5. The copper-chromium-zirconium alloy structure has at least more than 70% of substructure, and the substructure greatly improves the tensile strength of the copper-chromium-zirconium alloy.
Drawings
FIG. 1 is an SEM morphology of a primary phase in a copper-chromium-zirconium alloy at various stages of a thermomechanical treatment. (FIGS. 1 (a) and 1 (b) are as-cast SEM topographies, FIG. 1 (c) is an SEM topographies after a first cold deformation, FIG. 1 (d) is a solid solution SEM topographies, FIG. 1 (e) is an aging SEM topographies, and FIG. 1 (f) is an SEM topographies after a third cold deformation).
FIG. 2 is an XRD pattern of a copper-chromium-zirconium alloy in as-cast, first cold deformed, and solid solution state.
Fig. 3 is a stress-strain curve of a copper-chromium-zirconium alloy.
FIG. 4 is a graph showing the distribution of recrystallized structures, deformed structures and substructures in the copper-chromium-zirconium alloy of example 1.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
Preparation method of copper-chromium-zirconium alloy
The copper-chromium-zirconium alloy and the preparation method thereof provided by the application comprise vacuum smelting, vacuum horizontal continuous casting, first cold deformation, solution treatment, second cold deformation, aging treatment and third cold deformation which are sequentially carried out.
In the present invention, the raw materials for vacuum melting include electrolytic copper, cu-10wt.% Cr master alloy, cu-40wt.% Zr master alloy. The alloy composition is preferably (in mass percent): 0.8 to 1.0wt.%; zr:0.1 to 0.2wt.%; the balance of Cu and unavoidable impurities, and the total mass content of each component is 100%.
The specific source of the alloy raw material and the intermediate alloy composition are not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used. The alloy raw material can reduce the impurity content in the copper-chromium-zirconium alloy and further improve the performance of the alloy.
In the present invention, the temperature of the vacuum melting is preferably 1260.+ -. 10 ℃. If the temperature is lower than 1250 ℃, on the one hand, the escape of impurity gases in the melt is not facilitated, and on the other hand, the melt is easily blocked or stuck on the wall of a runner when being transferred to a holding furnace. Vacuumizing the furnace chamber to 5×10 before smelting and heating -2 Pa or less, then, 50000Pa inert gas is filled, and smelting is carried out under the protection of inert gas atmosphere.
In the invention, the inert gas is nitrogen or argon, and the purity is more than 99.99%.
In the invention, the crystallizer used for vacuum horizontal continuous casting is preferably a boron nitride and beryllium copper combined crystallizer, wherein the boron nitride end directly contacts copper alloy liquid, and the beryllium copper end is connected with a cooling water copper sleeve. The connection mode of the boron nitride and the beryllium copper is threaded connection or high-temperature glue connection. The boron nitride has good lubricity, wear resistance and high temperature resistance, and can ensure that the copper-chromium-zirconium casting blank has good surface quality; the beryllium copper has high strength and high elasticity, and can prolong the service life of the crystallizer. If a crystallizer made of other materials, such as graphite, is used, surface scratches are easily caused, and the service life is shorter.
In the invention, the vacuum horizontal continuous casting traction process is preferably as follows: traction pitch: 2-4 mm; traction speed: 1-6 mm/s; stop time: 0 to 0.5s; back-pushing time: 0 to 0.2s.
If the traction speed is too high, the surface temperature is high, the surface of the casting blank is easy to oxidize and blacken, and thermal cracking and even fracture can occur. If the pulling speed is too slow, the efficiency is too low and the front end of the strand may solidify, damaging the mold. The four continuous casting parameters of the traction pitch, the traction speed, the stop time and the reverse time are not isolated, and any parameter change can influence the surface quality of the casting blank.
In the present invention, the alloy must be subjected to a first cold deformation prior to solution treatment. The first cold deformation can bring deformation energy storage, provide recrystallization nucleation driving force, promote recrystallization and the dissolution of the excessive phase into the matrix. And meanwhile, deformation energy storage caused by cold deformation can accelerate the regulation and control process of the primary phase. If cold deformation is not performed before the solution treatment, the solution effect is insufficient, and a sufficient number of nano-sized precipitated phases cannot be precipitated in the subsequent aging precipitation process to strengthen the matrix. And meanwhile, insufficient morphology and distribution regulation of a primary phase can be caused. The invention can crush coarse grains in a casting state through the first cold deformation treatment, remarkably heal cracks, reduce or eliminate casting defects, convert an as-cast structure into a deformed structure and improve the processing performance of the alloy.
In the present invention, the total deformation amount of the first cold deformation is preferably 40% to 50%. The processing ratios of the deformed pass and the single pass are not particularly limited, and may be determined according to the technical common knowledge of a person skilled in the art.
In the present invention, the solution treatment temperature is preferably 900 to 950 ℃, more preferably 950 ℃. If the solid solution temperature is lower than 900 ℃, the solid solution is incomplete, the recrystallization is insufficient, and the subsequent processing and aging precipitation strengthening effect are affected. If the solid solution temperature is higher than 950 ℃, grains are liable to grow up, which is unfavorable for processing.
In the present invention, the total deformation amount of the second cold deformation is preferably not less than 95%. The large deformation amount deformation can induce the generation of the nano lamellar structure. The processing ratios of the deformed pass and the single pass are not particularly limited, and may be determined according to the technical common knowledge of a person skilled in the art. If the total deformation amount of the second cold deformation is less than 95%, enough nano lamellar structure cannot be generated, the dislocation density cannot meet the requirement, and the regulation and control of the substructure in the subsequent processing process are affected.
In the present invention, the aging treatment temperature is 460 to 500 ℃, more preferably 500 ℃. The aging treatment is carried out at 500 ℃, so that on one hand, the aging time can be shortened, and the purposes of energy conservation and emission reduction are achieved; on the other hand, the high-temperature aging excites the dislocation activity, the dislocation activity is larger, the dislocation is easy to locally gather and intertwine in the third cold deformation process, and dislocation groups are formed, so that the generation of a substructure is induced. The invention can improve the strength and the conductivity of the alloy and reduce the internal stress through aging treatment.
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 generation of substructure. The processing ratios of the deformed pass and the single pass are not particularly limited, and may be determined according to the technical common knowledge of a person skilled in the art.
In the invention, the cold deformation comprises common metal processing technologies such as drawing, rolling and the like.
In the present invention, a multi-stage deformation heat treatment process is employed, including three cold deformations and two heat treatments. Compared with the traditional copper alloy processing method, the method provided by the invention has the advantages that: the casting blank adopts a vacuum horizontal continuous casting method, so that the component stability and the surface quality of the Cu-Cr-Zr alloy casting blank are ensured. The multi-stage thermomechanical treatment process is combined, the morphology of the primary phase is regulated and controlled, the needle-shaped primary phase with damaged performance is regulated and controlled to be spherical with improved performance, on the other hand, the nano lamellar structure is generated through large plastic deformation induction and the substructure is generated through aging treatment, the synergistic effect among the working procedures is achieved, the combined microstructure of the nano lamellar structure, the nano primary phase, the nano precipitated phase and the nano substructure is formed, and the comprehensive performance of the Cu-Cr-Zr alloy is improved.
Method for regulating and controlling structural performance of copper-chromium-zirconium alloy
The method for regulating and controlling the tissue performance of the copper-chromium-zirconium alloy is a combination process of the thermomechanical treatment process, and the needle-shaped primary phase is regulated and controlled to be spherical after solution treatment; drawing and aging treatment with large deformation amount induce generation of nano lamellar structure and substructure. After the above-mentioned thermomechanical treatment, a unique and novel nano-structure is obtained in the copper-chromium-zirconium alloy matrix: a nano lamellar structure, a nano primary phase, a nano precipitated phase and a nano level substructure. Wherein the matrix phase is nano crystal grains with nano lamellar structure and comprises deformation twin crystal and more than 50% of substructure; more than 90% of the morphology of the primary phase is spherical. The primary phase and the precipitated phase are nailed and rolled on the grain boundary, so that the nano lamellar structure has high-temperature stability.
In the invention, the size of the spherical primary phase is 100-200 nm, and if the size of the spherical precipitated phase is more than 200nm, crack initiation is easy to cause, and alloy performance is affected.
In the invention, more than 80% of the spherical primary phase is distributed at the grain boundary, thereby ensuring the refining effect in solid solution and the function of increasing deformation resistance in the subsequent deformation process.
In the present invention, the width of the nanolayered structure is not more than 200nm.
In the present invention, the substructure refers to a crystal which is not completely recovered after cold working deformation or deformation, and grains whose original crystal orientation is substantially uniform are refined into small crystal masses whose orientations are slightly different (several minutes to several degrees). The Cu-Cr-Zr alloy forms a cellular substructure after cold plastic deformation. In the subsequent recovery process, dislocations in the cell walls gradually form a dislocation network of low energy state, and the cell walls become clearer and subgrain boundaries. The substructure may be identified by EBSD calibration.
In the invention, the proportion of the substructure is more than 70 percent.
The specific nanoscale mixed structure enables the copper-chromium-zirconium alloy to have the characteristics of high strength and high conductivity, and has excellent comprehensive performance.
In fact, none of the processes of the above preparation works in isolation, and the effects are reciprocal, wherein the adjustment of any one of the process parameters brings about a variation in the properties of the alloy. Each process has independent functions, but after the processes are combined, the processes are mutually excited and promoted, and the synergistic effect is obvious, so that the processing performance, mechanical property and physical property of the copper-chromium-zirconium alloy are obviously improved.
The present invention is not limited to the processing equipment and process parameters not mentioned in the above method, and may be applied to processing equipment and process parameters well known to those skilled in the art.
In order to further understand the present invention, the following examples are provided to illustrate the preparation and structure property regulation method of the high-strength high-conductivity copper-chromium-zirconium alloy, and the protection scope of the present invention is not limited by the following examples.
Example 1
(1) Vacuum horizontal continuous casting: the proportion is Cr:0.8wt.%, zr: melting copper-chromium-zirconium alloy with 0.2 wt% and the balance of copper in a vacuum induction melting furnace, transferring the alloy into a heat preservation furnace for standing when the temperature of copper liquid reaches 1270 ℃, and reducing the temperature to 1110 ℃ at the inlet of a crystallizer to start four-flow horizontal continuous casting traction; the traction process comprises the following steps: the traction pitch is 3mm, the traction speed is 1mm/s, the stop time is 0.5s, and the reverse thrust time is 0.2s.
(2) First cold deformation: performing first cold deformation of the copper-chromium-zirconium alloy casting blank with the total deformation amount of 50%;
(3) Primary phase regulation: primary phase regulation and control are carried out on the copper-chromium-zirconium alloy subjected to the first cold deformation treatment, wherein the treatment mode is that water quenching is immediately carried out after solution treatment is carried out for 60min at 950 ℃;
(4) Second cold deformation: carrying out second cold deformation on the copper-chromium-zirconium alloy subjected to solution treatment, wherein the deformation amount of the second cold deformation is 98.5%;
(5) Aging treatment: aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 500 ℃, and the aging time is 30min;
(6) Third cold deformation: and (3) carrying out third cold deformation with the deformation amount of 50% on the copper-chromium-zirconium alloy after the aging treatment.
The primary phase is changed into a sphere from a needle shape by the characteristics of SEM, EBSD and TEM, inherits in the process of thermomechanical treatment, and more than 80% of the primary phase is distributed in a grain boundary; the alloy is mainly in nano lamellar structure and substructure, and contains a certain amount of primary phase and precipitated phase. Wherein the average width of the nano lamellar structure is 120nm, and the proportion of the substructures is 64.5%. Through mechanical property and electrical property tests, the tensile strength reaches 730MPa, and the conductivity is 78% IACS.
Example 2
(1) Vacuum horizontal continuous casting: the proportion is Cr:0.8wt.%, zr: melting copper-chromium-zirconium alloy with 0.1 wt% and the balance of copper in a vacuum induction melting furnace, transferring the molten copper to a heat preservation furnace for standing when the temperature of the molten copper reaches 1250 ℃, and starting four-flow horizontal continuous casting traction when the temperature of the molten copper at an inlet of a crystallizer is 1090 ℃; the traction process comprises the following steps: the traction pitch is 4mm, the traction speed is 6mm/s, the stop time is 0s, and the reverse pushing time is 0s.
(2) First cold deformation: performing first cold deformation of the copper-chromium-zirconium alloy casting blank with the total deformation amount of 40%;
(3) Primary phase regulation: primary phase regulation and control are carried out on the copper-chromium-zirconium alloy subjected to the first cold deformation treatment, wherein the treatment mode is that water quenching is immediately carried out after solution treatment is carried out for 30min at 950 ℃;
(4) Second cold deformation: carrying out second cold deformation with the deformation amount of 95% on the copper-chromium-zirconium alloy subjected to solution treatment;
(5) Aging treatment: aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 500 ℃, and the aging time is 60min;
(6) Third cold deformation: and (3) carrying out third cold deformation with the deformation amount of 50% on the copper-chromium-zirconium alloy after the aging treatment.
The primary phase is changed into a sphere from a needle shape by the characteristics of SEM, EBSD and TEM, inherits in the process of thermomechanical treatment, and more than 80% of the primary phase is distributed in a grain boundary; the alloy is mainly in nano lamellar structure and substructure, and contains a certain amount of primary phase and precipitated phase. Wherein the average width of the nano lamellar structure is 116nm, and the proportion of the substructures is 53.2%. Through mechanical property and electrical property tests, the tensile strength reaches 749MPa, and the conductivity is 81% IACS.
Example 3
(1) Vacuum horizontal continuous casting: the proportion is Cr:0.8wt.%, zr: melting copper-chromium-zirconium alloy with 0.1 wt% and the balance of copper in a vacuum induction melting furnace, transferring the molten copper to a heat preservation furnace for standing when the temperature of the molten copper reaches 1260 ℃, and starting four-flow horizontal continuous casting traction when the temperature of the molten copper at an inlet of a crystallizer is 1100 ℃; the traction process comprises the following steps: the traction pitch is 2mm, the traction speed is 5mm/s, the stop time is 0.5s, and the reverse thrust time is 0.1s.
(2) First cold deformation: performing first cold deformation on the copper-chromium-zirconium alloy casting blank, wherein the total deformation of the casting blank is 43.75%;
(3) Primary phase regulation: primary phase regulation and control are carried out on the copper-chromium-zirconium alloy subjected to the first cold deformation treatment, wherein the treatment mode is that water quenching is immediately carried out after solution treatment is carried out for 60min at 950 ℃;
(4) Second cold deformation: carrying out secondary cold deformation on the copper-chromium-zirconium alloy subjected to solution treatment, wherein the deformation amount of the copper-chromium-zirconium alloy is 97.2%;
(5) Aging treatment: aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 500 ℃, and the aging time is 30min;
(6) Third cold deformation: and (3) carrying out third cold deformation with the deformation amount of 50% on the copper-chromium-zirconium alloy after the aging treatment.
The primary phase is changed into a sphere from a needle shape by the characteristics of SEM, EBSD and TEM, inherits in the process of thermomechanical treatment, and more than 80% of the primary phase is distributed in a grain boundary; the alloy is mainly in nano lamellar structure and substructure, and contains a certain amount of primary phase and precipitated phase. Wherein the average width of the nano lamellar structure is 124nm, and the proportion of the substructures is 74.2%. Through mechanical property and electrical property tests, the tensile strength reaches 803MPa, and the conductivity is 76% IACS.
Example 4 (comparative example)
(1) Vacuum horizontal continuous casting: the proportion is Cr:0.8wt.%, zr: melting copper-chromium-zirconium alloy with 0.1 wt% and the balance of copper in a vacuum induction melting furnace, transferring the molten copper to a heat preservation furnace for standing when the temperature of the molten copper reaches 1260 ℃, and starting four-flow horizontal continuous casting traction when the temperature of the molten copper at an inlet of a crystallizer is 1100 ℃; the traction process comprises the following steps: the traction pitch is 2mm, the traction speed is 5mm/s, the stop time is 0.5s, and the reverse thrust time is 0.1s.
(2) First cold deformation: carrying out first cold deformation on the copper-chromium-zirconium alloy casting blank with the total deformation amount of 45%;
(3) Primary phase regulation: primary phase regulation and control are carried out on the copper-chromium-zirconium alloy subjected to the first cold deformation treatment, wherein the treatment mode is that water quenching is immediately carried out after solution treatment for 60min at 900 ℃;
(4) Second cold deformation: carrying out second cold deformation with the deformation amount of 95% on the copper-chromium-zirconium alloy subjected to solution treatment;
(5) Aging treatment: aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 450 ℃, and the aging time is 120min;
(6) Third cold deformation: and (3) carrying out third cold deformation with the deformation amount of 50% on the copper-chromium-zirconium alloy after the aging treatment.
The primary phase is changed into a sphere from a needle shape by the characteristics of SEM, EBSD and TEM, inherits in the process of thermomechanical treatment, and more than 80% of the primary phase is distributed in a grain boundary; the alloy is mainly in nano lamellar structure and substructure, and contains a certain amount of primary phase and precipitated phase. Wherein the average width of the nano lamellar structure is 130nm, and the proportion of the substructures is 42.3%. Through mechanical property and electrical property tests, the tensile strength is 648MPa, and the conductivity is 80% IACS.
The as-cast tensile strength of the Cu-Cr-Zr alloy in example 1 was 256MPa, and the electrical conductivity was 38% IACS. After multistage plastic deformation and heat treatment process treatment and primary equal microstructure structure regulation, the tensile strength is improved to 730MPa, compared with an as-cast state, the tensile strength is improved to 474MPa, namely 2.85 times of the as-cast state, and meanwhile, the conductivity is improved from 38% IACS to 78% IACS, so that the improvement effect is remarkable. The multi-stage thermomechanical treatment process combined with the primary equal microstructure regulation and control method has good innovation and breakthrough. In example 2, compared with example 1, the solid solution time (from 60min to 30 min) and the aging time (from 30min to 60 min) are shortened, the proportion of the substructure is reduced, but the width of the nano lamellar structure is reduced, the aging time is longer, precipitation is more sufficient, the conductivity is slightly improved, and the tensile strength is also improved by 19MPa. In order to further improve the tensile strength of the Cu-Cr-Zr alloy, the thermomechanical treatment process is adjusted again. In the embodiment 3, the time for primary phase regulation (solution treatment time) is 60min, the primary phase regulation is more sufficient, more substructures are induced in the subsequent thermomechanical treatment process, the proportion of the substructures reaches 74.2%, and the substructure reinforcement effect is achieved, so that the tensile strength is remarkably improved, and exceeds 800MPa. Example 4 is a comparative example in which the primary phase control temperature was lower and the substructure ratio was only 42.3%, so the strength was only 648MPa. This means that each of the processes of the preparation method described above does not work in isolation and that the effects are reciprocal, wherein the adjustment of any one of the process parameters brings about a change in the properties of the alloy. Each process has independent functions, but after the processes are combined, the processes are mutually excited and promoted, and the synergistic effect is obvious, so that the processing performance, mechanical property and physical property of the copper-chromium-zirconium alloy are obviously improved.
FIG. 1 is an SEM morphology of a primary phase in a copper-chromium-zirconium alloy at various stages of a thermomechanical treatment. As can be seen from the graph, the vacuum horizontal continuous casting Cu-Cr-Zr alloy cast structure contains a large number of needle-shaped primary phases, and the morphology of the primary phases is changed into a sphere from the needle shape after the morphology of the primary phases is regulated (solution treatment) and is basically distributed at the grain boundary. In the subsequent cold deformation and aging process, the spherical primary phase does not deform and disappear, but inherits, the deformation resistance is increased, and the grain boundary movement is blocked, so that grains are refined, and the high-temperature stability of the nano lamellar structure is ensured.
Figure 2 XRD patterns of copper-chromium-zirconium alloy in as-cast, first cold deformed and solid solution state. It was found that the XRD pattern exhibited a Cr diffraction peak on the (110) crystal plane in addition to the Cu diffraction peak. Although the content of chromium element in the copper-chromium-zirconium alloy is only about 1wt.%, the existence of Cr element is still detected, which indicates that the primary Cr phase occupies a relatively large amount.
FIG. 3 is a stress strain curve for the copper chromium zirconium alloys of examples 1-3 and comparative examples. After primary phase regulation, the tensile strength of the alloy is obviously improved to more than 700MPa, and the highest tensile strength can reach more than 800MPa.
FIG. 4 is a graph showing the distribution of recrystallized structures, deformed structures and substructures in the copper-chromium-zirconium alloy of example 1. Wherein the proportion of the substructure exceeds 70%, and the performance of the alloy is greatly improved.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The preparation method of the copper-chromium-zirconium alloy is characterized by comprising the following steps of:
(1) Melting electrolytic copper, cu-Cr and Cu-Zr intermediate alloy in a vacuum induction melting furnace under the protection of argon atmosphere, transferring the molten copper to a heat preservation furnace for standing when the temperature of the molten copper is 1260+/-10 ℃, and starting four-flow horizontal continuous casting traction when the temperature of the molten copper at an inlet of a crystallizer is 1100+/-10 ℃ to obtain a copper-chromium-zirconium alloy casting blank;
(2) Performing first cold deformation of the copper-chromium-zirconium alloy casting blank with the deformation amount of 30% -50%;
(3) Carrying out solution treatment on the copper-chromium-zirconium alloy treated in the step (2) at 800-1000 ℃ for 30-60 min, and then immediately carrying out water quenching;
(4) Carrying out second cold deformation with the deformation amount of more than 95% on the copper-chromium-zirconium alloy subjected to solution treatment;
(5) Aging the copper-chromium-zirconium alloy obtained in the previous step, wherein the aging temperature is 400-500 ℃, and the aging time is 10-600 min;
(6) And (3) performing third cold deformation with the deformation of 40% -60% on the copper-chromium-zirconium alloy after the aging treatment.
2. The method of manufacturing according to claim 1, wherein: the copper-chromium-zirconium alloy consists of the following elements: chromium: 0.8 to 1.0wt.%; zirconium: 0.1 to 0.2wt.%; the balance of copper and unavoidable impurities, and the total mass of the contents of all components is 100%.
3. The method of manufacturing according to claim 1, wherein: the crystallizer material adopted in the step (1) is boron nitride and beryllium copper, wherein the boron nitride end directly contacts copper alloy liquid, and the beryllium copper end is connected with a cooling water copper sleeve.
4. The method of manufacturing according to claim 1, wherein: the vacuum horizontal continuous casting traction process in the step (1) comprises the following steps: traction pitch: 2-4 mm; traction speed: 1-6 mm/s; stop time: 0 to 0.5s; back-pushing time: 0 to 0.2s.
5. The method of manufacturing according to claim 1, wherein: the structure in the alloy comprises a matrix phase, a primary phase and a precipitated phase, wherein the matrix phase is nano crystal grains and a substructure of a nano lamellar structure.
6. The method of manufacturing according to claim 5, wherein: the size of the spherical primary phase is 100-200 nm, the ratio of the spherical primary phase to the spherical primary phase is 90%, and more than 80% of spherical primary phase is distributed at the grain boundary.
7. The method of manufacturing according to claim 5, wherein: the width of the nano layered structure is not more than 200nm.
8. The method of manufacturing according to claim 5, wherein: the proportion of the substructure is more than 70 percent.
9. The method of any one of claims 1-8, wherein: the tensile strength of the copper-chromium-zirconium alloy exceeds 700MPa, and the conductivity is more than 70% IACS.
10. The method of any one of claims 1-8, wherein: the tensile strength of the copper-chromium-zirconium alloy is more than 800MPa, and the conductivity is more than 75% IACS.
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