A method for accelerating the resolubilization of rare earth elements in a rare earth copper alloy during a solutionizing process

Abstract

A method for accelerating the resaturation of rare earth elements in a rare earth copper alloy during a solution treatment process, comprising the following steps: taking a copper alloy containing rare earth elements and processing it into a plate with a thickness of 3-10 mm; subjecting the plate to cryogenic treatment in a cryogenic tank, reducing its temperature to below -150 DEG C and maintaining it for 5-20 minutes; subjecting the plate after the cryogenic treatment to rolling deformation; repeating the second and third steps until the total rolling reduction reaches 30-50%, completing the cryogenic pre-deformation; waiting for the plate to stabilize to room temperature and subjecting it to solution treatment; quenching the plate after the solution treatment in water, rapidly cooling it to the water temperature, and obtaining a supersaturated solid solution structure. The present application adopts a combined process of cryogenic rolling pre-deformation and solution treatment, reduces the residual cerium-rich phase in the cerium-containing rare earth copper alloy, improves the solubility of cerium elements in the alloy matrix, further improves the role of cerium elements in the alloy, and obtains a cerium-containing rare earth copper alloy with more excellent performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rare earth copper alloy preparation, and particularly relates to a method for accelerating the resaturation of rare earth elements in a rare earth copper alloy during a solid solution treatment process, which can promote the dissolution of the rare earth element-rich phase in a copper-silver alloy containing rare earth elements. BACKGROUND

[0002] Copper alloys are widely used in the fields of electrical and electronic information due to their good strength, electrical conductivity, wear resistance, heat transfer performance, etc. With the rapid development of high-tech, higher requirements are put forward for the performance of high-performance copper alloys, especially high-strength and high-conductivity copper alloys. The addition of alloying elements greatly improves the low strength and low wear resistance of pure copper, but the scattering effect of alloying elements on electrons also significantly reduces the electrical conductivity. How to balance the relationship between strength and electrical conductivity has become a long-term topic in the research of copper alloys.

[0003] Due to the good electrical conductivity of copper and silver in the metal industry, copper-silver alloy naturally becomes an important candidate for the research of high-strength and high-conductivity copper alloys. The addition amount of silver determines the high performance of copper-silver alloy. In-situ fiber reinforced copper-silver alloy containing 6wt.% to 30wt.% has extremely high strength (up to about 1.7 GPa) and good electrical conductivity after large strain deformation, but the high price of silver limits the popularization of copper-silver alloy in general industrial applications. In order to reduce the cost of the alloy, a small amount of rare earth element cerium is added to the alloy after appropriately reducing the silver content, so that the solid solution strengthening, fine grain strengthening, and purification and impurity removal effects of the rare earth element in the alloy can make up for the performance decline caused by the reduction of silver content. In addition, the added rare earth element cerium, as the most abundant rare earth element in the earth's crust, is also much cheaper than silver.

[0004] Pure cerium has a lower melting point than pure copper and pure silver, and the rare earth copper-silver alloy containing cerium often has a cerium-rich phase after melting and casting. Solid solution treatment is usually used to promote the uniform distribution of cerium elements in the alloy, so that more cerium elements can fully participate and play a better effect. However, in the actual solid solution process, even if the solid solution temperature is increased or the holding time is prolonged, there are still cerium-rich phases in the alloy after solid solution treatment, which are difficult to completely dissolve, which is not conducive to the efficient use of cerium elements. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a method for accelerating the resaturation of rare earth elements in a rare earth copper alloy during a solid solution treatment process, to solve the problem of the difficulty of completely dissolving the cerium-rich phase in a cerium-containing rare earth copper alloy under the traditional solid solution treatment system, to promote the dissolution of the difficult-to-dissolve cerium-rich phase in the cerium-containing rare earth copper alloy, and to improve the utilization rate of cerium elements.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A method for accelerating the resolubilization of rare earth elements in a rare earth copper alloy during a solution treatment process, comprising:

[0008] Step 1: Take a copper alloy containing rare earth elements and process it into a plate with a thickness of 3-10 mm;

[0009] Step 2: Perform cryogenic treatment on the plate in a cryogenic tank, reducing its temperature to below -150°C and maintaining it for 5-20 minutes;

[0010] Step 3: Perform rolling deformation on the plate after cryogenic treatment;

[0011] Step 4: Repeat steps 2 and 3 until the total rolling reduction rate reaches 30-50%, completing the cryogenic pre-deformation;

[0012] Step 5: After the plate stabilizes to room temperature, perform solution treatment on it;

[0013] Step 6: Quench the solution-treated plate in water to rapidly cool it to water temperature, obtaining a supersaturated solid solution structure.

[0014] In one embodiment, the first step involves preliminarily hot deforming or cutting the copper alloy containing rare earth elements to process it into a plate.

[0015] In one embodiment, the third step involves rolling at a speed of 1.0-3.0 m / min and a single-pass reduction rate of 5-7%.

[0016] In one embodiment, the fourth step involves selecting a corresponding total rolling reduction rate based on the proportion of rare earth element-rich phases. When the proportion of rare earth-rich phases is low, the pre-rolling reduction rate is selected to be 30%. When the proportion of rare earth-rich phases increases, the total rolling reduction rate increases to 50%.

[0017] In one embodiment, the fifth step involves using argon gas protection during the solution process to prevent oxidation of the copper alloy.

[0018] In one embodiment, the solution treatment conditions are a temperature of 700-1000°C and a holding time of 1-10 h.

[0019] In one embodiment, the copper alloy containing rare earth elements is a copper-silver alloy containing cerium elements, with the silver content being 4-10% by weight, the cerium element content being 0.05-0.08%, and the remainder being copper.

[0020] In one embodiment, the silver content is 5%, the cerium element content is 0.075%, and the remainder is copper.

[0021] Compared with existing technologies, the present invention provides a method for accelerating the redissolution of rare earth elements in rare earth copper alloys during solution treatment. It employs deep cryogenic rolling pre-deformation to increase the dislocation density in the rare earth copper alloy. Simultaneously, it breaks down some rare earth-rich phases to activate the activity of rare earth cerium elements. Then, it performs solution treatment to reduce the residual cerium-rich phases in cerium-containing rare earth copper alloys, increase the solubility of cerium elements in the alloy matrix, further enhance the role of cerium elements in the alloy, and obtain cerium-containing rare earth copper alloys with superior performance.

[0022] The cerium-containing rare earth copper alloy prepared by the method of this invention, compared with the traditional single solid solution treatment system under the same conditions, allows more cerium-rich phases to dissolve in the matrix after solid solution treatment, providing the possibility to fully utilize the role of cerium and obtain a more superior cerium-containing rare earth copper alloy. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of the method for accelerating the redissolution of rare earth elements in rare earth copper alloys during the solution treatment process according to the present invention. In the diagram, (a) represents deep cryogenic treatment before rolling; (b) represents pre-deformation during rolling; and (c) represents argon-protected solution treatment followed by water quenching. The black phase segregated at the grain boundaries in microstructures 1 and 2 in the diagram represents the rare earth-rich phase.

[0024] Figure 2 These are metallographic images of the products obtained in each step of the embodiments of the present invention. Detailed Implementation

[0025] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0026] like Figure 1 As shown, this invention employs cryogenic rolling pre-deformation combined with solution treatment to accelerate the redissolution of rare earth elements in rare earth copper alloys, and mainly includes the following steps:

[0027] Step 1: Material selection: A copper alloy containing cerium rare earth elements, prepared by casting method, with a cerium content of 0.05-0.08%. After preliminary hot deformation or cutting, it is processed into plates with a thickness of 3-10 mm.

[0028] Step 2: Place the rare earth copper alloy plate into a liquid nitrogen cryogenic chamber for cryogenic treatment. When the temperature of the plate drops to below -150℃, keep it at that temperature for 5 to 20 minutes.

[0029] Step 3: Roll the cryogenically treated sheet material at a rolling speed of 1.0–5.0 m / min and a single-pass reduction rate of 5–7%.

[0030] Step 4: Repeat steps 2 and 3 until the total rolling reduction reaches 30-50%. Select the appropriate total rolling reduction according to the different requirements for alloy properties to complete the cryogenic pre-deformation process.

[0031] Fifth step: after the completion of the pre-deformation by cryogenic rolling, the plate is transported to the heat treatment workshop after being stabilized to room temperature.

[0032] Sixth step: the plate is subjected to solid solution treatment in the heat treatment workshop, argon protection is adopted in the solid solution process to prevent the copper alloy from being seriously oxidized, the solid solution treatment temperature is 700-1000℃, the holding time is 1-10h, and the cerium element is solid-solved.

[0033] Seventh step: the plate after the solid solution treatment is rapidly quenched in water to cool it to the water temperature quickly, and a supersaturated solid solution structure is obtained.

[0034] The main principle of the present application is that: through the pre-deformation by cryogenic rolling, firstly, the coarse and segregated cerium-rich rare earth element phase existing in the alloy can be broken, the copper / rare earth element interface area is increased, and the space basis for accelerating the dissolution of the rare earth element-rich phase is provided; secondly, the low-temperature environment of the pre-deformation by cryogenic rolling can inhibit the dynamic recovery of dislocations in the alloy, and higher dislocation density is brought, meanwhile, the dislocation cells formed by a large number of dislocations can further hinder the grain boundary migration, the grain boundary density is increased, the grain refinement is realized, and the high-energy crystal defects such as grain boundaries and dislocations provide the energy basis for the dissolution of the rare earth element in the subsequent solid solution treatment process.

[0035] The residual of the rare earth element-rich phase in the rare earth element-containing copper alloy prepared by the method is less, the distribution of the rare earth element is more uniform, the utilization rate of the rare earth element and the performance of the alloy are higher. Due to the good effect of promoting the dissolution of the rare earth-rich phase, the method has a broad application prospect in the field of rare earth copper alloy production and manufacturing.

[0036] In one specific embodiment of the present application, taking the dissolution of the cerium-rich phase in the cerium-containing rare earth copper-silver alloy as an example, referring to FIG. 1, the method mainly includes the following steps: Figure 1

[0037] First step: a cerium-containing rare earth copper-silver alloy with a thickness of 2mm is adopted, the material composition and content are shown in Table 1. The metallographic structure is observed, at this time, a large number of white silver-rich phases and a small amount of light gray cerium-rich phases exist in the alloy, as shown in FIG. 1a, i.e. the metallographic structure 1 in FIG. 1. Figure 2 Figure 1

[0038] Table 1 Composition of cerium-containing rare earth copper-silver alloy (wt. %)

[0039] Element class Ag Ce Cu Content 5.00 0.075 Balance

[0040] Second step: the cerium-containing rare earth copper-silver alloy plate is placed in liquid nitrogen for cryogenic treatment, and the temperature of the plate is reduced to-196℃ and kept for 10 minutes.

[0041] ​​​Third step: the plate after cryogenic treatment is rolled, the rolling speed is 2.0 m / min, and the single pass reduction is 5%.

[0042] Fourth step: repeat the second and third steps until the total rolling reduction reaches 50%, and the cryogenic pre-deformation process is completed.

[0043] Fifth step: after the completion of cryogenic rolling pre-deformation, the plate is transported to the heat treatment workshop after being stabilized to room temperature, and its metallographic structure is observed, that is, Figure 1 the metallographic structure 2, at this time the white phase and gray phase in the alloy are elongated, some coarse white phases are broken, see Figure 2 b in the figure.

[0044] Sixth step: the cryogenic rolling pre-deformed plate and the plate without cryogenic rolling pre-deformation are solid solution treated in the heat treatment workshop, argon protection is adopted in the solid solution process to prevent serious oxidation of the copper alloy, the solid solution treatment temperature is 780℃, and the holding time is 1h.

[0045] Seventh step: the plate after solid solution treatment is rapidly quenched in water to cool it to water temperature quickly to obtain a supersaturated solid solution structure, and its metallographic structure is observed, no obvious white phase or gray phase is observed in the plate after cryogenic rolling pre-deformation + solid solution treatment, see Figure 2 d in the figure, indicating that the silver-rich phase and cerium-rich phase are all re-dissolved into the copper matrix. However, a gray second phase is observed in the plate treated by traditional solid solution treatment only, see Figure 2 c in the figure.

Claims

1. A method for accelerating the redissolution of rare earth elements in rare earth copper alloys during solid solution treatment, characterized in that, include: Step 1: Take a copper alloy containing rare earth elements and process it into a plate with a thickness of 3~10mm; the copper alloy containing rare earth elements is a copper-silver alloy containing cerium elements, with a silver content of 4~10% and a cerium content of 0.05~0.08% by weight, and the balance being copper. Step 2: Place the plate in a cryogenic chamber to perform cryogenic treatment, lowering its temperature to below -150℃ and holding it at that temperature for 5 to 20 minutes; Step 3: Rolling and deforming the cryogenically treated sheet metal; Step 4: Repeat steps 2 and 3 until the total rolling reduction reaches 30-50%, completing the deep cryogenic pre-deformation; Step 5: After the board material has stabilized to room temperature, perform a solution treatment on it; Step 6: Quench the solution-treated plate in water to rapidly cool it to the water temperature, thereby obtaining a supersaturated solid solution structure.

2. The method for accelerating the redissolution of rare earth elements in rare earth copper alloys during the solution treatment process according to claim 1, characterized in that, The first step involves processing a copper alloy containing rare earth elements into a sheet material through preliminary hot deformation or cutting.

3. The method for accelerating the redissolution of rare earth elements in rare earth copper alloys according to claim 1, characterized in that, In the third step, the rolling speed is 1.0~3.0 m / min, and the single-pass reduction rate is 5~7%.

4. The method for accelerating the redissolution of rare earth elements in rare earth copper alloys during the solution treatment process according to claim 1, characterized in that, The fourth step involves selecting the appropriate total rolling reduction rate based on the proportion of rare earth element-enriched phases. When the proportion of rare earth-enriched phases is low, the pre-rolling reduction rate is selected as 30%. When the proportion of rare earth-enriched phases increases, the total rolling reduction rate increases to 50%.

5. The method for accelerating the redissolution of rare earth elements in rare earth copper alloys during the solution treatment process according to claim 1, characterized in that, In the fifth step, the solution treatment process is protected by argon gas to prevent oxidation of the copper alloy.

6. The method for accelerating the redissolution of rare earth elements in rare earth copper alloys during the solution treatment process according to claim 1 or 5, characterized in that, The solution treatment conditions are: temperature 700~1000℃, holding time 1~10 h.

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