A rare earth copper chromium alloy material and its preparation method

Abstract

The present invention relates to a rare earth copper chromium alloy material and a preparation method thereof. The main technical solution adopted is as follows: in terms of weight percentage, the chemical composition of the rare earth copper chromium alloy material includes: 0.1 - 2.0 wt% of Cr, rare earth elements greater than 0 and less than or equal to 200 ppm, unavoidable impurity elements not exceeding 0.005 wt%, and the balance being copper; among them, the preparation method of the rare earth copper chromium alloy material includes the following steps: 1) melting and casting the raw materials to obtain an ingot; 2) performing homogenization treatment on the ingot to obtain a homogenized alloy ingot; 3) successively performing hot forging treatment, solution treatment, primary cold deformation treatment, and aging treatment on the homogenized alloy ingot to obtain the rare earth copper chromium alloy material; among them, the cold deformation amount of the primary cold deformation treatment is 50 - 90%. The present invention is mainly used to improve the electrical conductivity and high-temperature thermal stability of copper chromium alloy by adding ultra-trace rare earth elements and introducing a cold and heat treatment system with a large deformation amount.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metals, in particular to a rare earth copper-chromium alloy material and a preparation method thereof. Background Art

[0002] Due to their good comprehensive properties, the application of copper and copper alloys in many high-tech fields has increased year by year, especially the Cu-Cr series alloys, which are widely used in electrical contacts, contact wires, lead frames and aerospace technology fields.

[0003] In addition to having a certain strength, this type of alloy also requires good electrical conductivity and high-temperature thermal stability. However, the surface structure of existing Cu-Cr alloys is coarse and the precipitated Cr phase is unstable. In addition, the Cu grains tend to grow abnormally at high temperatures, which greatly reduces the overall performance of the material. In the existing technology, alloying elements are usually added to improve its organizational properties. For example, Zr is added to inhibit recrystallization and the growth of the Cr phase to achieve a grain refinement effect and improve its strength. Compared with Zr, rare earth has higher chemical activity and can interact with almost all elements except inert gases. It also has the ability to absorb gases and is known as "industrial MSG". As the name suggests, adding a small amount of rare earth can make the material performance better.

[0004] The following existing related technologies are reports on the preparation and performance of rare earth copper-chromium alloys.

[0005] The first related technology produces a highly conductive, high-strength, and high-ductility rare earth copper alloy (rare earth content of 0.02-0.15%) with a tensile strength greater than 630 MPa, a conductivity greater than 80% IACS, an elongation greater than 10%, and a softening temperature greater than 520°C. This technology primarily improves the alloy's strength, conductivity, and softening temperature by limiting the alloy's composition and proportions and manipulating conventional preparation processes. However, this technology does not address the alloy's structural stability under high-temperature conditions.

[0006] A second related technology uses powder metallurgy to produce a Cu-Cr (0.1-2.0)-Y (0.1-1.0) alloy. This alloy exhibits excellent electrical conductivity and softening resistance, with a tensile strength exceeding 480 MPa, a conductivity exceeding 85% IACS, and a softening temperature exceeding 800°C. However, this powder metallurgy method has certain limitations for large-scale production.

[0007] A third related technology discloses a method for preparing a rare earth copper-chromium-zirconium alloy (with a rare earth content of 0.05-0.1%) using a Cu-La master alloy through arc melting. This method eliminates the need for solution treatment, saving production costs. However, this method cannot be produced on a large scale and the melting process is difficult.

[0008] In summary, the existing technologies mainly improve the strength, electrical conductivity and anti-softening temperature of alloys by adding elements and changing the preparation methods. However, it is difficult to simultaneously improve all properties. Moreover, usually, the improvement of the anti-softening temperature is very limited on the premise of maintaining a certain alloy strength and electrical conductivity. In particular, there are few reports on improving the microstructure and properties of alloys at high temperatures (such as above 900 °C). In addition, the existing microalloying methods usually have complex types of added elements, increasing the process difficulty and cost. Although methods such as powder metallurgy have significantly improved the anti-softening temperature, they are limited to a certain extent in large-scale production. Summary of the Invention

[0009] In view of this, the present invention provides a rare earth copper-chromium alloy material and a preparation method thereof. The main purpose is to improve the electrical conductivity and high-temperature thermal stability of copper-chromium alloys by adding ultra-trace rare earth elements and introducing a cold heat treatment system with a large deformation amount.

[0010] To achieve the above object, the present invention mainly provides the following technical solutions:

[0011] On the one hand, an embodiment of the present invention provides a preparation method of a rare earth copper-chromium alloy material. In terms of weight percentage, the chemical composition of the rare earth copper-chromium alloy material includes: 0.1-2.0 wt% of Cr, rare earth elements (RE) greater than 0 and less than or equal to 200 ppm, unavoidable impurity elements not exceeding 0.005 wt%, and the balance is copper. The preparation method of the rare earth copper-chromium alloy material includes the following steps:

[0012] 1) Melting and casting the raw materials to obtain an ingot;

[0013] 2) Performing homogenization treatment on the ingot to obtain a homogenized alloy ingot;

[0014] 3) Sequentially performing hot forging treatment, solution treatment, primary cold deformation treatment, and aging treatment on the homogenized alloy ingot to obtain a rare earth copper-chromium alloy material. The cold deformation amount of the primary cold deformation treatment is 50-90%.

[0015] Preferably, the rare earth element (RE) is one or more of La, Ce, and Y.

[0016] Preferably, the ratio of the content of the rare earth element to the content of the Cr element is 0.005-0.01.

[0017] Preferably, in step 1): the raw materials include raw materials for providing rare earth elements; among them, the raw materials for providing rare earth elements include Cu-xRE master alloy; where x is 15-25%, and the oxygen content in the Cu-xRE master alloy is less than 5 ppm; and / or the raw materials are melted under the conditions of 1200-1400 °C and a protective atmosphere.

[0018] Preferably, in step 1): the protective atmosphere is nitrogen or argon;

[0019] Preferably, in step 1): load Cu and Cr into the crucible, place the Cu-xRE master alloy in the secondary feeding tray, and wrap it with copper foil to prevent the Cu-xRE master alloy from being oxidized at high temperature; evacuate, adjust the power, and start heating to 1200-1250 °C. After Cu and Cr are completely melted, increase the power and adjust the temperature to 1300-1400 °C for refining to remove the gas therein. When there is no boiling on the surface of the solution, fill with argon, add the Cu-xRE master alloy in the secondary tray into the crucible, and then perform in-furnace impact melting and casting.

[0020] In step 1): the casting temperature is 1100-1150 °C.

[0021] Preferably, in step 2): the temperature of the homogenization treatment is 900-1000 °C; preferably, at the temperature of the homogenization treatment, keep warm for 1-10 h.

[0022] Preferably, in the hot forging treatment of step 3): the initial forging temperature is 750-950 °C, and the final forging temperature is 700-800 °C; and / or the forging ratio is 2-6.

[0023] Preferably, in the solution treatment of step 3): the temperature of the solution treatment is 880-980 °C; preferably, at the temperature of the solution treatment, keep warm for 0.5-10 h; preferably, after the solution treatment, water quenching treatment is required; preferably, the temperature error of the solution treatment does not exceed ±5 °.

[0024] Preferably, in the first cold deformation treatment of step 3), it includes multi-pass cold deformation; where the deformation amount of each pass is not greater than 20% compared to the deformation amount of the previous pass. Preferably, in the aging treatment of step 3): the aging treatment temperature is 350-500 °C; the aging treatment time is 0.5-8 h.

[0025] In one aspect, an embodiment of the present invention provides a rare earth copper chromium alloy material. In terms of weight percentage, the chemical composition of the rare earth copper chromium alloy material includes: 0.1 - 2.0 wt% of Cr, rare earth element RE greater than 0 and less than or equal to 200 ppm, unavoidable impurity elements not exceeding 0.005 wt%, and the balance being copper; preferably, the rare earth copper chromium alloy material is heat-preserved at a temperature of 900 - 980 °C for 1 - 4 h and then cooled with the furnace, and after that, its average grain size is less than 25 μm, the electrical conductivity is greater than 80% IACS, the hardness is greater than 50 HV, and the volume percentage of annealing twins is 40 - 80%; preferably, the rare earth copper chromium alloy material is prepared by the preparation method of the rare earth copper chromium alloy material described in any one of the above.

[0026] Compared with the prior art, the rare earth copper chromium alloy material and its preparation method of the present invention at least have the following beneficial effects:

[0027] The preparation method of the rare earth copper chromium alloy material provided by the present invention, without reducing the electrical conductivity of the alloy, adjusts the content distribution of the phases at the matrix grain boundaries, pins the grain boundaries, inhibits the growth of grains, and improves the high-temperature thermal stability by adding ultra-trace rare earth elements and combining a reasonable cold and heat treatment system with large deformation. In addition, the ultra-trace rare earth can purify the matrix and improve the electrical conductivity. Finally, it achieves the effect of replacing the role of zirconium element in the copper chromium alloy, thereby reducing the cost. Here, the rare earth copper chromium alloy material prepared by the present invention, after high-temperature treatment, realizes: (1) fine grains; specifically, the grain size of the rare earth copper chromium alloy material prepared by the present invention is finer than that of the Cu-Cr alloy and the Cu-Cr-Zr alloy; (2) better electrical conductivity and hardness performance.

[0028] In summary, the preparation method of the rare earth copper chromium alloy material provided by the present invention, by adding ultra-trace rare earth elements and combining a reasonable cold and heat treatment system with large deformation, obtains a rare earth copper chromium alloy material with high electrical conductivity and high thermal stability, which can meet the use requirements of high-temperature service environments. After high-temperature sintering treatment at 980 °C × 3 h, the rare earth copper chromium alloy material still maintains a good tissue and performance state, with an average grain size less than 25 μm, an electrical conductivity greater than 80% IACS, and a hardness greater than 50 HV.

[0029] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines the drawings to describe in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the IPF diagram of the alloy material after high-temperature heat treatment (heat-preserved at a high temperature of 900 - 980 °C for 1 - 4 h and then cooled with the furnace); wherein, Figure 1Figure a in it is the IPF diagram of the rare earth copper chromium alloy material (Cu-1Cr-100 ppm La) prepared in Example 1; Figure b is the IPF diagram of Cu-1Cr prepared in Comparative Example 1; Figure c is the IPF diagram of Cu-1Cr-0.1Zr prepared in Comparative Example 2.

[0031] Figure 2 It is the grain distribution diagram of the alloy material after high-temperature heat treatment (holding at a temperature of 900 - 980 °C for 1 - 4 h and cooling with the furnace); among them, Figure 1 Figure a in it is the grain distribution diagram of the rare earth copper chromium alloy material (Cu-1Cr-100 ppm La) prepared in Example 1; Figure b is the grain distribution diagram of Cu-1Cr prepared in Comparative Example 1; Figure c is the grain distribution diagram of Cu-1Cr-0.1Zr prepared in Comparative Example 2. Specific Embodiments

[0032] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following combines the accompanying drawings and preferred embodiments to detail the specific embodiments, structures, features, and their effects of the application according to the present invention. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0033] The present invention mainly prepares a high-conductivity and high-thermal-stability alloy material with ultra-trace rare earth alloying through conventional methods, and has simple composition, simple process, and cost savings. Specifically, the present invention prepares a Cu-Cr alloy system by adding ultra-trace rare earth and reducing or not adding Zr element, which can achieve better performance effects and thus reduce costs. The present invention improves the conductivity and high-temperature thermal stability of the alloy by reasonably configuring the rare earth elements and their contents and introducing a cold heat treatment system with a large deformation amount.

[0034] On the one hand, an embodiment of the present invention provides a preparation method of a rare earth copper chromium alloy material. Among them, in terms of weight percentage, the chemical composition of the rare earth copper chromium alloy material includes: 0.1 - 2.0 wt% of Cr, rare earth elements greater than 0 and less than or equal to 200 ppm, inevitable impurity elements not exceeding 0.005 wt%, and the balance is copper; among them, the preparation method of the rare earth copper chromium alloy material includes the following steps:

[0035] 1) Melting and casting the raw materials to obtain an ingot.

[0036] The raw materials include raw materials for providing rare earth elements; among them, the raw materials for providing rare earth elements include Cu-xRE master alloy; where x is 15-25%, and the oxygen content in the Cu-xRE master alloy is less than 5 ppm. Here, adding rare earth in the form of master alloy has the following advantages: 1) reducing the oxidation loss of rare earth during melting and facilitating the precise control of rare earth composition in the ingot; 2) making the distribution of rare earth in the melt more uniform and reducing segregation; 3) reducing the oxygen content in pure rare earth metals and reducing the introduction of impurities. The proportion range of rare earth in the master alloy can ensure its easy preparation, uniform composition, and convenient processing.

[0037] The raw materials are melted at 1200-1400 °C under a protective atmosphere; preferably, the protective atmosphere is nitrogen or argon.

[0038] 2) Perform homogenization treatment on the ingot to obtain a homogenized alloy ingot.

[0039] The temperature of the homogenization treatment is 900-1000 °C; preferably, at the temperature of the homogenization treatment, the holding time is 1-10 h. Preferably, the homogenization cooling method is air cooling.

[0040] 3) Perform hot forging treatment, solution treatment, primary cold deformation treatment, and aging treatment on the homogenized alloy ingot in sequence to obtain a rare earth copper chromium alloy material; among them, the cold deformation amount of the primary cold deformation treatment is 50-90%.

[0041] Preferably, double milling is performed after the solution treatment to remove the defects on the surface of the sheet after the solution treatment.

[0042] Among them, in the hot forging treatment: the initial forging temperature is 750-950 °C, the final forging temperature is 700-800 °C, and the forging ratio is 2-6.

[0043] In the solution treatment: the temperature of the solution treatment is 880-980 °C; preferably, at the temperature of the solution treatment, the holding time is 0.5-10 h; after the solution treatment is completed, water quenching treatment is required; the temperature error of the solution treatment does not exceed ±5 °.

[0044] In the primary cold deformation treatment: it includes multi-pass cold deformation; preferably, the deformation amount of each pass is not greater than 20% compared with the deformation amount of the previous pass.

[0045] In the aging treatment: the temperature of the aging treatment is 350-500 °C; the time of the aging treatment is 0.5-8 h.

[0046] Preferably, in the above steps, the rare earth element is one or more of La, Ce, and Y. The ratio of the content of the rare earth element to the content of the Cr element is 0.005-0.01.

[0047] Here, regarding a preparation method of a rare earth copper chromium alloy material provided by an embodiment of the present invention, it should be noted that:

[0048] 1. The present invention realizes the preparation of a Cu-Cr-rare earth alloy, and this alloy still maintains a relatively fine and uniform structure, as well as good strength and conductivity after high-temperature heat treatment. The alloy components (including Cr, Zr, rare earth) and process conditions involved in the related technologies mentioned in the background art are different from those of the present invention. In addition, the prior art does not mention the tissue performance after high-temperature heat treatment.

[0049] 2. The present invention first reasonably controls the addition amount of rare earth, especially strictly requires the ratio of the Cr content to the rare earth content, so that the excess rare earth content is relatively low and will not cause excessive chemical reactions to the Cr element, and the effect of the Cr element is retained.

[0050] By combining a cold and heat treatment system process with a large deformation amount, the excess rare earth primary phase is evenly and finely distributed, which can play a role in refining the matrix structure and pinning grain boundaries during the hot deformation process. The rare earth primary phase can be retained at the grain boundaries, and during subsequent cold deformation and heat treatment processes, it can also induce the precipitation of Cr phases near it, achieving the effect of regulating the content of the precipitated phases at the grain boundaries. These precipitated phases play a strong pinning role in the growth of the recrystallized structure during the high-temperature heat treatment process, thereby improving the high-temperature thermal stability.

[0051] 3. The cold and heat treatment system with a large deformation amount includes hot forging treatment, primary cold deformation treatment, and aging treatment. Specifically as follows: 1) Through the hot forging treatment with a "large deformation amount": Since the added rare earth elements will form relatively large-sized hard particle-like primary phases in the alloy matrix, during the hot forging treatment process, these rare earth hard particle primary phases will play a role in breaking the matrix structure. At the same time, under the action of large deformation, the primary phases will also be fragmented and evenly distributed, inhibiting the growth of dynamically recrystallized grains; after the hot forging treatment, the alloy composition is uniform and the structure is uniform and fine. 2) Through the "primary cold deformation" treatment: The above-mentioned recrystallized structure undergoes severe plastic deformation to meet the required size requirements and accumulate sufficient deformation energy storage; in addition, a fibrous structure is formed in the alloy, and the rare earth phase will be distributed along the deformation direction. 3) Through "heat treatment", that is, aging treatment: Due to the change in the solid solubility of solute atoms and the driving force of the deformation energy storage, it is easier to precipitate dispersed and fine second-phase particles in the alloy matrix. At this time, due to the action of elastic distortion energy around the primary rare earth phase, it will attract the second-phase particles to precipitate preferentially near it.

[0052] 4. The existing processes generally include two types: (1) Plate and strip materials: hot forging - solution treatment - hot rolling - first cold rolling - heat treatment - second cold rolling (or without the second cold rolling); (2) Wire materials: hot extrusion - first cold drawing - solution treatment - second cold drawing - aging. Compared with the above existing technologies, the process of the present invention has fewer steps, and the introduction of rare earth primary phase particles plays an improving role on the deformed microstructure.

[0053] On the other hand, the embodiment of the present invention provides a rare earth copper chromium alloy material. By weight percentage, the chemical composition of the rare earth copper chromium alloy material includes: 0.1 - 2.0 wt% of Cr, rare earth element RE greater than 0 and less than or equal to 200 ppm, inevitable impurity elements not exceeding 0.005 wt%, and the balance is copper; preferably, the rare earth copper chromium alloy material is held at a temperature of 900 - 980 °C for 1 - 4 h, and after furnace cooling, the average grain size is less than 25 μm, the electrical conductivity is greater than 80% IACS, the hardness is greater than 50 HV, and the volume percentage of annealing twins is 40 - 80%; wherein, the above rare earth copper chromium alloy material is prepared by the preparation method of the rare earth copper chromium alloy material described in any one of the above.

[0054] The following is further detailed through specific examples as follows:

[0055] Example 1

[0056] In this example, a rare earth copper chromium alloy material is prepared; by weight percentage, the rare earth copper chromium alloy material of this example contains: 1 wt% Cr, 100 ppm La, inevitable impurity elements not exceeding 0.005 wt%, and the balance is copper.

[0057] The main preparation steps are as follows:

[0058] 1) Vacuum induction melting: After weighing the raw materials according to the above weight percentages, put the electrolytic copper plate and pure Cr block into the crucible, put the Cu - 20RE master alloy into the secondary feeding tray, wrap it with copper foil to prevent it from being oxidized at high temperature, evacuate to about 10 Pa, adjust the power, and start heating. At this time, the temperature is about 1200 °C. After 20 min, the Cu block and Cr block are completely melted; increase the power, adjust the temperature to 1300 - 1400 °C for refining, mainly removing the gas therein. After about 30 min, there is no boiling on the surface of the solution, fill in argon, add the Cu - La master alloy in the secondary tray into the crucible, and then perform in - furnace flushing and melting, and casting. The casting temperature is about 1150 °C, and cool to room temperature to obtain an ingot.

[0059] 2) Homogenization treatment: Hold the ingot at a temperature of 920 ± 10 °C for 2 h; wherein, the cooling method after homogenization treatment is air cooling.

[0060] 3) Hot forging of ingot: Hot forging treatment is carried out on the homogenized alloy ingot; among them, the initial forging temperature is 900 °C, and the final forging temperature ≥ 700 °C (specifically 750 °C), and it is forged into an alloy with a width of 100 mm and a thickness of 20 mm; among them, the forging ratio is 5.

[0061] 4) Solution treatment: Solution treatment is carried out on the alloy after hot forging treatment; among them, the solution treatment temperature is 880 ± 10 °C, the total holding time is 1 h, and then water quenching treatment is carried out.

[0062] 5) Double milling: Remove the defects on the surface of the sheet after solution treatment, and the milling depth is 0.2 mm.

[0063] 6) First cold deformation: First cold deformation treatment is carried out on the alloy after milling; among them, the cold deformation amount is 80% (4 passes of cold deformation are carried out, which are 30%, 20%, 15%, 15% in sequence);

[0064] 7) Aging treatment is carried out on the alloy after the first cold deformation treatment; among them, the aging treatment temperature is 430 °C, and the holding time is 2 h to obtain the rare earth copper chromium alloy material.

[0065] The rare earth copper chromium alloy material prepared in this example is held at a temperature of 980 °C for 3 h, and the average grain size after furnace cooling is 23.1 μm, the conductivity is 80.21% IACS, and the hardness is 50.14 HV.

[0066] Example 2

[0067] This example prepares a rare earth copper chromium alloy material; among them, calculated by weight percentage, the rare earth copper chromium alloy material of this example contains: 1.5 wt% Cr, 150 ppm La, unavoidable impurity elements not exceeding 0.005 wt%, and the balance is copper.

[0068] The main preparation steps are as follows:

[0069] 1) Vacuum induction melting: After weighing the raw materials according to the above weight percentage, put the electrolytic copper plate and pure Cr block into the crucible, put the Cu-15RE master alloy into the secondary feeding tray, wrap it with copper foil to prevent it from being oxidized at high temperature, evacuate to about 10 Pa, adjust the power, and start heating. At this time, the temperature is about 1200 °C. After 20 min, the Cu block and Cr block are completely melted; increase the power, adjust the temperature to 1300 - 1400 °C for refining, mainly removing the gas in it. After about 30 min, there is no boiling on the surface of the solution, fill in argon, add the Cu-La master alloy in the secondary tray into the crucible, and then carry out in-furnace punching and melting, and casting. The casting temperature is about 1150 °C, and it is cooled to room temperature to obtain the ingot.

[0070] 2) Homogenization treatment: Keep the ingot at a temperature of 920 ± 10 °C for 2 h; among them, the cooling method after homogenization treatment is air cooling.

[0071] 3) Hot forging of the ingot: Conduct hot forging treatment on the alloy ingot after homogenization treatment; among them, the initial forging temperature is 900 °C, the final forging temperature ≥ 700 °C (specifically 750 °C), and forge it into an alloy with a width of 100 mm and a thickness of 20 mm; among them, the forging ratio is 5.

[0072] 4) Solution treatment: Conduct solution treatment on the alloy after hot forging treatment; among them, the solution treatment temperature is 880 ± 10 °C, the total holding time is 1 h, and then water quenching treatment is carried out.

[0073] 5) Double milling: Remove the defects on the surface of the sheet after solution treatment, and the milling depth is 0.2 mm.

[0074] 6) Primary cold deformation: Conduct primary cold deformation treatment on the alloy after milling; among them, the cold deformation amount is 80% (4 passes of cold deformation are carried out, which are 30%, 20%, 15%, and 15% in sequence);

[0075] 7) Conduct aging treatment on the alloy after primary cold deformation treatment; among them, the aging treatment temperature is 440 °C, the holding time is 2 h, and the rare earth copper chromium alloy material is obtained.

[0076] The rare earth copper chromium alloy material prepared in this example is kept at a temperature of 980 °C for 3 h, and the average grain size after furnace cooling is 20.5 μm, the conductivity is 78.45% IACS, and the hardness is 55.60 HV.

[0077] Comparative Example 1

[0078] Comparative Example 1 prepares a copper chromium alloy material; among them, by weight percentage, the copper chromium alloy material of Comparative Example 1 contains: 1 wt% Cr, the total sum of inevitable impurity elements does not exceed 0.005 wt%, and the rest is copper.

[0079] The main preparation methods include:

[0080] Vacuum induction melting: After weighing the raw materials according to the above weight percentage, put the electrolytic copper plate and pure Cr block into the crucible, evacuate to about 10 Pa, adjust the power, and start heating. At this time, the temperature is about 1200 °C. After 20 min, the Cu block and Cr block are completely melted; increase the power, adjust the temperature to 1300 - 1400 °C for refining, mainly removing the gas in it. After about 30 min, there is no boiling on the surface of the solution, and then in-furnace casting is carried out. The casting temperature is about 1200 °C, and it is cooled to room temperature to obtain the ingot.

[0081] The ingot is subjected to homogenization treatment, hot forging treatment, solution treatment, double milling treatment, primary cold rolling deformation treatment and aging treatment to obtain a copper-chromium alloy material. Among them, the processes of homogenization treatment, hot forging treatment, solution treatment, double milling treatment, primary cold rolling deformation treatment and aging treatment refer to Example 1.

[0082] The copper-chromium alloy material prepared in Comparative Example 1 was held at a high temperature of 980 °C for 3 h, and the average grain size after furnace cooling was 36.2 μm, the conductivity was 72.43% IACS, and the hardness was 46.87 HV.

[0083] Comparative Example 2

[0084] A copper-chromium-zirconium alloy material is prepared in Comparative Example 2; among them, by weight percentage, the copper-chromium-zirconium alloy material in Comparative Example 2 contains: 1 wt% Cr, 0.1 wt% Zr, the total sum of inevitable impurity elements does not exceed 0.005 wt%, and the rest is copper.

[0085] The main preparation methods include:

[0086] Vacuum induction melting: After weighing the raw materials according to the above weight percentages, put the electrolytic copper plate and pure Cr block into the crucible, put the pure Zr or Cu-Zr master alloy wrapped in copper foil into the secondary feeding tray, evacuate to about 10 Pa, adjust the power, and start heating. At this time, the temperature is about 1200 °C. After 20 min, the Cu block and Cr block are completely melted; increase the power, adjust the temperature to 1300-1400 °C for refining, mainly removing the gas therein. After about 30 min, there is no boiling on the surface of the solution, fill in argon, add the pure Zr or Cu-Zr master alloy wrapped in copper foil in the secondary tray into the crucible, and then perform in-furnace flushing and melting, casting. The casting temperature is about 1200 °C, and it is cooled to room temperature to obtain an ingot.

[0087] The ingot is subjected to homogenization treatment, hot forging treatment, solution treatment, double milling treatment, primary cold rolling deformation treatment and aging treatment to obtain a copper-chromium alloy material. Among them, the processes of homogenization treatment, hot forging treatment, solution treatment, double milling treatment, primary cold rolling deformation treatment and aging treatment refer to Example 1.

[0088] The copper-chromium-zirconium alloy material prepared in Comparative Example 2 was held at a high temperature of 980 °C for 3 h, and the average grain size after furnace cooling was 59.4 μm, the conductivity was 66.10% IACS, and the hardness was 49.98 HV.

[0089] Comparative Example 3

[0090] A rare earth copper-chromium alloy material is prepared in Comparative Example 3; here, the chemical composition of the rare earth copper-chromium alloy material in Comparative Example 3 is the same as that in Example 1, but the preparation method is different.

[0091] The preparation method of Comparative Example 3 mainly includes the following steps:

[0092] 1) Vacuum induction melting: After weighing the raw materials according to the above weight percentages, put the electrolytic copper plate and pure Cr block into the crucible, and place the metallic La in the secondary feeding tray. Wrap it with copper foil to prevent it from being oxidized at high temperatures. Pump the vacuum to about 10 Pa, adjust the power, and start heating. At this time, the temperature is about 1200 °C. After 20 minutes, the Cu block and Cr block are completely melted. Increase the power, adjust the temperature to 1300 - 1400 °C for refining, mainly removing the gases therein. After about 30 minutes, there is no boiling on the surface of the solution. Fill in argon, add the La metal in the secondary tray into the crucible, and then perform in-furnace punching and melting, and casting. The casting temperature is about 1200 °C, and cool it to room temperature to obtain an ingot.

[0093] 2) Homogenization treatment: Keep the ingot at a temperature of 920 ± 10 °C for 2 h; among them, the cooling method after homogenization treatment is air cooling.

[0094] 3) Solution treatment: The alloy after homogenization treatment is subjected to solution treatment; among them, the solution treatment temperature is 880 ± 10 °C, and the total holding time is 1 h, and then water quenching treatment is carried out.

[0095] 4) Double milling: Remove the defects on the surface of the sheet after solution treatment, and the milling depth is 0.2 mm.

[0096] 5) Primary cold deformation: Carry out primary cold deformation treatment on the alloy after milling; among them, the cold deformation amount is 80%;

[0097] 6) Aging treatment is carried out on the alloy after primary cold deformation treatment; among them, the aging treatment temperature is 430 °C, and the holding time is 2 h to obtain a rare earth copper-chromium alloy material.

[0098] The average grain size of the rare earth copper-chromium alloy material prepared in Comparative Example 3 is 45.2 μm after holding at 980 °C for 3 h and cooling with the furnace, the conductivity is 77.6% IACS, and the hardness is 45.50 HV.

[0099] Comparative Example 4

[0100] Prepare a rare earth copper-chromium alloy material in Comparative Example 4; calculated by weight percentage, the rare earth copper-chromium alloy material prepared in Comparative Example 4 contains: 1 wt% Cr, 0.1 wt% La, the total sum of inevitable impurity elements does not exceed 0.005 wt%, and the rest is copper.

[0101] The preparation method of the rare earth copper-chromium alloy material in Comparative Example 4 is the same as that in Example 1.

[0102] The average grain size of the rare earth copper chromium alloy material prepared in Comparative Example 4 was 55.4 μm after being held at 980 °C for 3 h and cooled with the furnace, the conductivity was 70.10% IACS, and the hardness was 50.20 HV.

[0103] See Table 1 for the comprehensive performance data of Examples 1-2 and Comparative Examples 1-4.

[0104] Table 1

[0105]

[0106] In addition, Figure 1 is the IPF diagram of the alloy material after high-temperature heat treatment (held at 980 °C for 3 h and cooled with the furnace); among them, Figure 1 Figure a in is the IPF diagram of the rare earth copper chromium alloy material (Cu-1Cr-100 ppm La) prepared in Example 1; Figure b is the IPF diagram of Cu-1Cr prepared in Comparative Example 1; Figure c is the IPF diagram of Cu-1Cr-0.1Zr prepared in Comparative Example 2.

[0107] Figure 2 is the grain distribution diagram of the alloy material after high-temperature heat treatment (held at 980 °C for 3 h and cooled with the furnace); among them, Figure 1 Figure a in is the grain distribution diagram of the rare earth copper chromium alloy material (Cu-1Cr-100 ppm La) prepared in Example 1; Figure b is the grain distribution diagram of Cu-1Cr prepared in Comparative Example 1; Figure c is the grain distribution diagram of Cu-1Cr-0.1Zr prepared in Comparative Example 2.

[0108] Here, from Table 1 and Figure 1 , Figure 2 it can be seen that:

[0109] (1) From Table 1, Figure 1 and Figure 2 it can be clearly seen that: compared with Comparative Example 1 and Comparative Example 2, after high-temperature heat treatment, the grains of the rare earth copper chromium alloy material prepared in the examples of the present invention are finer than those of the Cu-Cr alloy and the Cu-Cr-Zr alloy. Thus, compared with similar alloys, after high-temperature heat treatment, the rare earth copper chromium alloy material prepared in the examples of the present invention has an obvious grain refinement effect. And after high-temperature heat treatment, the rare earth copper chromium alloy material prepared in the examples of the present invention also has good strength and high conductivity.

[0110] It should be noted here that: other similar alloys and other similar rare earth alloys in the prior art cannot achieve the comprehensive effect of having fine grains, high conductivity, and good strength after high-temperature heat treatment.

[0111] (2) Compared with Comparative Example 3 and Comparative Example 4, the rare earth copper chromium alloy material prepared in the examples of the present invention has fine grain size and excellent conductivity. This shows that the chemical composition design and the preparation process design of the rare earth copper chromium alloy material in the examples of the present invention have a synergistic effect, and the two work together to improve the microscopic properties and macroscopic performance of the rare earth copper chromium alloy material.

[0112] (3) Compared with the comparative examples, after the rare earth copper chromium alloy material prepared in the examples of the present invention is subjected to high-temperature heat treatment, the content of annealing twins is high, which is beneficial to tissue stability and strength improvement.

[0113] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a rare earth copper chromium alloy material, characterized in that, In terms of weight percentage, the chemical composition of the rare earth copper chromium alloy material includes: 0.1-2.0 wt% of Cr, rare earth elements greater than 0 and less than or equal to 200 ppm, unavoidable impurity elements not exceeding 0.005 wt%, and the balance being copper; wherein, the ratio of the content of the rare earth elements to the content of the Cr element is 0.005-0.01; wherein, the preparation method of the rare earth copper chromium alloy material includes the following steps: 1) Melting and casting the raw materials to obtain an ingot; 2) Performing homogenization treatment on the ingot to obtain a homogenized alloy ingot; 3) Sequentially performing hot forging treatment, solution treatment, primary cold deformation treatment, and aging treatment on the homogenized alloy ingot to obtain a rare earth copper chromium alloy material; wherein, the cold deformation amount of the primary cold deformation treatment is 50-90%; wherein, in the hot forging treatment, the forging ratio is 2-6; in the primary cold deformation treatment, it includes multi-pass cold deformation.

2. The preparation method of the rare earth copper chromium alloy material according to claim 1, wherein, The rare earth elements are one or more of La, Ce, and Y.

3. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the step 1): The raw materials include raw materials for providing rare earth elements; wherein, the raw materials for providing rare earth elements include Cu-xRE master alloy; wherein, x is 15-25%, and the oxygen content in the Cu-xRE master alloy is lower than 5 ppm; and / or Melting the raw materials at 1200-1400 °C under a protective atmosphere; and / or Loading Cu and Cr into a crucible, placing the Cu-xRE master alloy in a secondary feeding tray, and wrapping it with copper foil to prevent the Cu-xRE master alloy from being oxidized at high temperature; evacuating, adjusting the power, starting to heat to 1200-1250 °C, waiting for Cu and Cr to melt completely, then increasing the power, adjusting the temperature to 1300-1400 °C for refining to remove the gas therein, waiting until there is no boiling on the surface of the solution, filling with argon, adding the Cu-xRE master alloy in the secondary tray into the crucible, and then performing in-furnace flushing and melting and casting; and / or The casting temperature is 1100-1150 °C.

4. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the step 2): The temperature of the homogenization treatment is 900-1000 °C.

5. The preparation method of the rare earth copper chromium alloy material according to claim 4, wherein, In the step 2): At the temperature of the homogenization treatment, keep warm for 1-10 h.

6. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the hot forging treatment of the step 3): The initial forging temperature is 750-950 °C, and the final forging temperature is 700-800 °C.

7. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the solution treatment of the step 3): The temperature of the solution treatment is 880-980 °C.

8. According to claim 7, the preparation method of the rare earth copper chromium alloy material is characterized in that At the temperature of the solution treatment, keep warm for 0.5-10 h.

9. The preparation method of the rare earth copper chromium alloy material according to claim 7, characterized in that, After the solution treatment, water quenching treatment needs to be carried out.

10. According to claim 7, the preparation method of the rare earth copper chromium alloy material is characterized in that The temperature error of the solution treatment does not exceed ±5 °C.

11. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the primary cold deformation treatment of the step 3); The deformation amount of each pass is not greater than 20% compared with the deformation amount of the previous pass.

12. The preparation method of the rare earth copper chromium alloy material according to claim 1 or 2, characterized in that, In the aging treatment of the step 3): The aging treatment temperature is 350 - 500 °C; the aging treatment time is 0.5 - 8 h.

13. A rare earth copper chromium alloy material, characterized in that, The rare earth copper chromium alloy material is prepared by the preparation method of the rare earth copper chromium alloy material according to any one of claims 1 - 12.

14. The rare earth copper chromium alloy material according to claim 13, characterized in that, The rare earth copper chromium alloy material is held at a temperature of 900 - 980 °C for 1 - 4 h, and after furnace cooling, its average grain size is less than 25 μm, the electrical conductivity is greater than 80% IACS, the hardness is greater than 50 HV, and the volume percentage of annealing twins is 40 - 80%.

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