High-strength and high-conductivity Cu-Cr-Mg-Si alloy material and preparation method thereof

Abstract

The invention belongs to the field of high-strength and high-conductivity copper materials, and relates to a high-strength and high-conductivity Cu-Cr-Mg-Si alloy material and a preparation method thereof.The alloy comprises, by weight, 0.65%-1.15% of Cr, 0.15% of Mg, 0.02% of Si and the balance Cu; the preparation method comprises the following steps: (1) smelting and casting to obtain a cast ingot; (2) homogenization treatment; (3) hot rolling deformation; (4) solution treatment; (5) pre-aging treatment; (6) performing cold rolling deformation for the first time; (7) secondary aging treatment; (8) secondary cold rolling deformation; and (9) carrying out third aging treatment to obtain the alloy. According to the high-strength and high-conductivity Cu-Cr-Mg-Si alloy, by optimizing the alloy components and the preparation process, the comprehensive performance of Cu-Cr series alloy is remarkably improved, the tensile strength of the alloy reaches 628 MPa or above, the electric conductivity exceeds 79.4% IACS, and the high-strength and high-conductivity Cu-Cr-Mg-Si alloy is far better than that of traditional Cu-Cr alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-strength and high-conductivity copper materials, and relates to a high-strength and high-conductivity Cu-Cr-Mg-Si alloy material and a preparation method thereof. BACKGROUND

[0002] In the field of modern industry, high-strength and high-conductivity copper alloys are key materials for promoting the development of many industries. As a typical representative of the fourth generation of high-strength and high-conductivity copper alloys, Cu-Cr alloys occupy a pivotal position due to their outstanding performance. They have the remarkable characteristics of high strength, high electrical conductivity and high thermal conductivity, which makes them widely used in fields such as electronic information integrated frame materials and high-speed rail contact lines that have strict requirements on material performance.

[0003] Cu-Cr binary alloys exhibit excellent electrical conductivity, with a conductivity of more than 90% IACS. This characteristic makes them stand out among many copper alloys. However, this alloy also has obvious shortcomings. Its tensile strength is relatively low, making it difficult to meet the requirements of some high-mechanical-property application scenarios. More critically, during aging, the precipitated phase is extremely unstable and easily grows and coarsens, leading to overaging. Overaging can cause a sharp decline in the performance of the alloy, greatly limiting its application in higher performance requirements. To overcome these defects of Cu-Cr binary alloys, researchers have conducted extensive and in-depth research. They have thoroughly explored the aging phase change sequence of Cu-Cr alloys, analyzed the influence of the third component on alloy performance, and systematically studied the organizational evolution law during the processing deformation. Based on these research results, researchers have successfully developed Cu-Cr-Zr alloys.

[0004] However, Cu-Cr-Zr alloys still have some problems that need to be solved. Zr is a highly active element and is easily burned during alloy preparation, making it difficult to accurately control the alloy composition and leading to uneven composition. Moreover, this alloy still suffers from the problem of easy overaging, which to some extent affects its performance stability and reliability and limits its further application. Therefore, it is of great practical significance to develop a new alloy with more stable performance and better meet the needs of industry. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a high-strength and high-conductivity Cu-Cr-Mg-Si alloy material and a preparation method thereof, to improve the mechanical and electrical properties of Cu-Cr alloys, and to reduce costs by using inexpensive alloy elements.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] In one aspect, the application provides a high-strength and high-conductivity Cu-Cr-Mg-Si alloy material, which comprises the following components in percentage by weight: Cr 0.65% to 1.15%, Mg 0.15%, Si 0.02%, and the balance being Cu.

[0008] The alloy promotes fine and dispersed distribution of Cr precipitated phase by adding Mg and Si elements, Mg is segregated at the Cr phase interface to hinder the coarsening of precipitated phase and delay overaging, and Si realizes deoxidization purification and assists precipitation, thereby improving the tensile strength, yield strength and conductivity of the alloy, while reducing the preparation cost.

[0009] Further, the Cr content of the alloy is 1% to 1.15% to optimize the balance between the strengthening effect of Cr precipitated phase and the electrical conductivity performance.

[0010] In another aspect, the application also provides a preparation method of the high-strength and high-conductivity Cu-Cr-Mg-Si alloy material, which comprises the following steps:

[0011] (1) melting and casting to obtain an ingot;

[0012] (2) homogenization treatment;

[0013] (3) hot rolling deformation;

[0014] (4) solid solution treatment;

[0015] (5) pre-aging treatment;

[0016] (6) first cold rolling deformation;

[0017] (7) second aging treatment;

[0018] (8) second cold rolling deformation;

[0019] (9) third aging treatment to obtain the alloy.

[0020] The preparation method introduces initial Cr phase nucleation cores through pre-aging, and promotes fine and uniform distribution of precipitated phase in subsequent alternating cold rolling and aging, solves the problems of overaging and insufficient strength of Cu-Cr alloy, and realizes short-process high-performance preparation.

[0021] In the application, after the pre-aging treatment of the high-strength and high-conductivity Cu-Cr-Mg-Si alloy material, the increased dislocation density induced by cold rolling deformation is combined with the pinning effect of Cr phase particles, further refining the grains and improving the precipitated phase density, realizing the performance level of tensile strength ≥628MPa and conductivity ≥79.4%IACS.

[0022] Further, in step (1), the melting temperature is 1200-1400 DEG C, and the holding time is 3-10 min; water-cooling square mold is used for casting to form a cuboid ingot, so as to ensure uniform distribution of alloy elements and inhibit pore defects.

[0023] Further, in step (2), the homogenization temperature is 900-960 DEG C, the holding time is 1-12 h, and charcoal is placed in the furnace to prevent oxidation; the homogenization eliminates the dendritic segregation of the ingot, and provides a homogeneous matrix for subsequent Cr precipitation.

[0024] Further, in step (3), the temperature is cooled to 900 DEG C before hot rolling, and the deformation amount is 60-80%; the hot rolling breaks the ingot structure, eliminates casting defects, and provides deformation energy storage for subsequent Cr phase precipitation.

[0025] Further, in step (4), the solid solution temperature is 900-960 DEG C, the holding time is 1-2 h, and water quenching is used for cooling; the solid solution dissolves the second phase, ensures that Cr and Mg are fully solid-solved in the solid solution, and prepares conditions for pre-aging nucleation.

[0026] Further, in steps (5) and (9), the pre-aging and third aging temperatures are both 400-500 DEG C, the time is 1-12 h, and water quenching is used for cooling; the pre-aging forms initial Cr phase particles as pinning sites, and enhances the grain refinement effect of subsequent cold rolling.

[0027] Further, in steps (6) and (8), the cold rolling temperature is room temperature, and the deformation amount is both 40-60%.

[0028] Further, in step (7), the second aging temperature is 450 DEG C, and the time is 1-12 h; the alternating cold rolling and aging cooperates with the interface regulation of Mg / Si, maximizes the density of Cr precipitated phase and inhibits its coarsening, and realizes the synergistic improvement of the strength and conductivity of the alloy.

[0029] The beneficial effects of the present application are:

[0030] Compared with the prior art, the high-strength and high-conductivity Cu-Cr-Mg-Si alloy of the present application significantly improves the comprehensive performance of the Cu-Cr alloy by optimizing the alloy composition and the preparation process. The Cr content in the alloy is controlled at 0.65% to 1.15%, Mg is 0.15%, Si is 0.02%, and the balance is Cu. By using inexpensive Mg and Si elements to replace Zr, the problem of easy burning loss and uneven composition of Zr is avoided. Mg promotes the nucleation of Cr precipitated phase and segregates at the Cr phase interface, hindering the coarsening of the precipitated phase and delaying the overaging phenomenon; Si plays a role of deoxidizing and purifying the matrix, assisting the uniform distribution of Cr precipitation. This composition design not only reduces the preparation cost, but also makes the tensile strength of the alloy reach more than 628 MPa and the electrical conductivity exceed 79.4% IACS (as shown in Examples 1 and 2), which is much better than the traditional Cu-Cr-Zr alloy.

[0031] The preparation method of the present application introduces a pre-aging process as a key innovation, which forms initial Cr phase particles as nucleation cores after solid solution treatment at 400°C to 500°C for 1 to 12 hours. Subsequently, through alternating cold rolling (room temperature, deformation of 40% to 60%) and aging (450°C, 1 to 12 hours), the high dislocation density induced by cold rolling and the pinning effect of Cr phase particles are used to further refine the grains and increase the density of precipitated phase. This multi-step synergistic mechanism accelerates the microstructure evolution, avoids the risk of overaging of single aging, and realizes efficient preparation in a short process. For example, compared with Comparative Example 1 without pre-aging, the present method increases the yield strength by about 14% and the electrical conductivity by more than 5%.

[0032] Overall, the technical solution realizes the synergistic optimization of strength and electrical conductivity, and is suitable for high-speed rail contact wires and electronic frames and other high-demand fields. Compared with the prior art, it not only improves the mechanical and electrical properties, but also ensures the process repeatability and industrialization potential through details such as charcoal oxidation prevention and water quenching, and finally provides an economic and efficient solution for high-strength and high-conductivity copper materials.

[0033] Other advantages, objects, and features of the present application will be in part apparent and in part pointed out hereinafter. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the specification as follows. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, in which:

[0035] Figure 1 TEM image of the Cu-Cr-Mg-Si alloy after aging and rolling in Example 1. DETAILED DESCRIPTION

[0036] The present application is described in greater detail by the following specific examples, and other advantages and effects of the present application will be readily appreciated by skilled in the art from this disclosure. The present application can also be carried out or implemented by other different specific embodiments, and various modifications or changes can be made based on different views and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only schematically illustrate the basic concept of the present application, and the following examples and features in the examples can be combined with each other without conflict.

[0037] The drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as a limitation of the present application; in order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0038] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and should not be understood as a limitation of the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0039] Example 1

[0040] (1) Select 1.15wt.% of Cr metal, 0.15wt.% of Mg metal, and 0.02wt.% of Si and 98.68wt.% of pure copper as raw materials, put the raw materials into a vacuum melting furnace for heating, after the metal is melted, wait for 3min to cast ingot.

[0041] (2) Put the ingot into a muffle furnace for homogenization treatment for 2h, the temperature is 960℃, put charcoal in the furnace during homogenization to prevent oxidation, after homogenization, cool to 900℃ with the furnace. Then directly take out the sample and use a double roller mill for hot rolling treatment, the reduction is 80%, after hot rolling, put the sample into water for water cooling treatment, and then polish the surface with a grinding machine to obtain a hot rolled plate.

[0042] (3) Place the hot-rolled sheet in a muffle furnace and keep it at 960°C for 2 hours. During this time, put charcoal in the furnace to prevent oxidation. After the heat preservation is completed, put the sheet in water to cool it down quickly.

[0043] (4) Place the solid solution plate in a muffle furnace for heat preservation for 1 hour at a temperature of 450°C, and then cool it with water after the heat preservation is completed.

[0044] Then, cold rolling is performed at room temperature with a reduction of 60%.

[0045] (5) The cold-rolled sheet was placed in a muffle furnace and held at 450°C for 12 hours. After holding, it was cooled with water. Then, it was cold-rolled at room temperature with a reduction of 50%. Finally, it was held at 450°C for 5 minutes to obtain the final sample.

[0046] like Figure 1 The image shown is a TEM image of the Cu-Cr-Mg-Si alloy prepared in this embodiment after aging and rolling. It can be seen that a finely dispersed Cr precipitate phase is formed in the alloy, with a high dislocation density, which significantly improves the mechanical properties of the alloy.

[0047] Example 2

[0048] (1) Select 0.65wt.% Cr metal, 0.15wt.% Mg metal, 0.02wt.% Si and 99.18wt.% pure copper as raw materials, put the raw materials into a vacuum melting furnace for heating, and wait 3 minutes after the metal melts before casting to obtain an ingot.

[0049] (2) The ingot was placed in a muffle furnace for homogenization treatment for 2 hours at a temperature of 960°C. Charcoal was placed in the furnace during homogenization to prevent oxidation. After homogenization, the ingot was cooled to 900°C in the furnace. The sample was then taken out and hot rolled using a twin-roll mill with a reduction of 80%. After hot rolling, the sample was placed in water for water cooling treatment and then its surface was polished using a grinding wheel to obtain hot-rolled sheet.

[0050] (3) Place the hot-rolled sheet in a muffle furnace and keep it at 960°C for 2 hours. During this time, put charcoal in the furnace to prevent oxidation. After the heat preservation is completed, put the sheet in water to cool it down quickly.

[0051] (4) Place the solid solution plate in a muffle furnace for heat preservation for 1 hour at a temperature of 450°C, and then cool it with water after the heat preservation is completed.

[0052] Then, cold rolling is performed at room temperature with a reduction of 60%.

[0053] (4) The cold-rolled plate is put into a muffle furnace for heat preservation, the time is 12 h, and the temperature is 450 °C. After heat preservation, water cooling is performed. Cold rolling is performed at room temperature, and the reduction is 50%. Finally, heat preservation is performed at 450 °C for 5 min to obtain the final sample.

[0054] Comparative Example 1: No pre-aging treatment after solution

[0055] (1) 1.15 wt.% of Cr metal, 0.15 wt.% of Mg metal, and 0.02 wt.% of Si and 98.68 wt.% of pure copper are selected as raw materials, and the raw materials are put into a vacuum melting furnace for heating. After the metal is melted, 3 min is waited for casting to obtain an ingot.

[0056] (2) The ingot is put into a muffle furnace for 2 h of homogenization treatment, and the temperature is 960 °C. Charcoal is put into the furnace during homogenization to prevent oxidation. After homogenization, the furnace is cooled to 900 °C. Then, the sample is directly taken out and hot-rolled using a double-roller rolling machine, with a reduction of 80%. After hot rolling, the sample is put into water for water cooling treatment, and then the surface is polished using a grinding machine to obtain a hot-rolled plate.

[0057] (3) The hot-rolled plate is put into a muffle furnace for heat preservation, and the temperature is 960 °C. Charcoal is put into the furnace during heat preservation to prevent oxidation. After heat preservation, the plate is quickly cooled in water. Cold rolling is performed at room temperature, and the reduction is 60%.

[0058] (4) The cold-rolled plate is put into a muffle furnace for heat preservation, the time is 12 h, and the temperature is 450 °C. After heat preservation, water cooling is performed. Cold rolling is performed at room temperature, and the reduction is 50%. Finally, heat preservation is performed at 450 °C for 5 min to obtain the final sample.

[0059] Comparative Example 2: Second aging time is 2 h

[0060] (1) 1.15 wt.% of Cr metal, 0.15 wt.% of Mg metal, and 0.02 wt.% of Si and 98.68 wt.% of pure copper are selected as raw materials, and the raw materials are put into a vacuum melting furnace for heating. After the metal is melted, 3 min is waited for casting to obtain an ingot.

[0061] (2) The ingot is put into a muffle furnace for 2 h of homogenization treatment, and the temperature is 960 °C. Charcoal is put into the furnace during homogenization to prevent oxidation. After homogenization, the furnace is cooled to 900 °C. Then, the sample is directly taken out and hot-rolled using a double-roller rolling machine, with a reduction of 80%. After hot rolling, the sample is put into water for water cooling treatment, and then the surface is polished using a grinding machine to obtain a hot-rolled plate.

[0062] (3) The hot-rolled plate was put into a muffle furnace for 2 h at 960 °C, charcoal was put into the furnace to prevent oxidation during the process, and after the heat preservation was completed, the plate was quickly cooled in water.

[0063] (4) The solution-treated plate was put into a muffle furnace for heat preservation for 1 h at 450 °C, and then water-cooled. Cold rolling was performed at room temperature with a reduction of 60%.

[0064] (5) The cold-rolled plate was put into a muffle furnace for heat preservation for 2 h at 450 °C, and then water-cooled. Cold rolling was performed at room temperature with a reduction of 50%. Finally, the heat preservation was performed at 450 °C for 5 min to obtain the final sample.

[0065] Comparative Example 3: The step (1) after the first cold rolling deformation treatment was not performed, 1.15 wt.% of Cr metal, 0.15 wt.% of Mg metal, and 0.02 wt.% of Si and 98.68 wt.% of pure copper were selected as raw materials, the raw materials were put into a vacuum melting furnace for heating, and after the metal was melted, it was cast into an ingot after waiting for 3 min.

[0066] (2) The ingot was put into a muffle furnace for homogenization treatment for 2 h at 960 °C, charcoal was put into the furnace to prevent oxidation during the homogenization process, and after the homogenization was completed, the sample was directly taken out and hot-rolled using a double-roller rolling mill with a reduction of 80%, and after the hot rolling was completed, the sample was water-cooled, and then the surface was polished using a grinding machine to obtain a hot-rolled plate.

[0067] (3) The hot-rolled plate was put into a muffle furnace for 2 h at 960 °C, charcoal was put into the furnace to prevent oxidation during the process, and after the heat preservation was completed, the plate was quickly cooled in water.

[0068] (4) The solution-treated plate was put into a muffle furnace for heat preservation for 1 h at 450 °C, and then water-cooled. Cold rolling was performed at room temperature with a reduction of 60%.

[0069] (5) The cold-rolled plate was put into a muffle furnace for heat preservation for 12 h at 450 °C, and then water-cooled.

[0070] Table 1 Material test results of different examples and test examples

[0071]

[0072] As shown in Table 1, different Cr contents have certain influence on the performance of the alloy, and the increase of Cr content improves the performance of the alloy to some extent, which is mainly that higher Cr content has more dispersed fine precipitates, and the strengthening effect of the alloy is more significant. According to Comparative Example 1, it can be seen that the effect of pre-aging is very significant, which plays a role in refining the grain, increasing the dislocation density and hindering the coarsening of precipitates, and realizes the improvement of strength and conductivity, which is mainly that during the pre-aging process, a certain amount of Cr phase small particles will be precipitated in the matrix, and when cold rolling is carried out, the Cr phase particles will become the core of dislocation encounter and interaction. The dislocation needs very large strain force when passing through the Cr particle area, that is, the Cr phase produces a pinning effect on the dislocation, which will lead to further subdivision of the microstructure, so that the grain refinement effect of the cold rolled alloy after pre-aging is stronger, and the micro-strain is more severe. In addition, this small particle can also be called the nucleation core of the precipitate, which makes the number of precipitates increase, thereby reducing the coarsening degree of the precipitates. Comparative Example 2 shows that the time required for the second aging is relatively long, so that the Cr phase can be fully precipitated. Comparative Example 3 shows the necessity of the second cold rolling and aging, and this process has a great influence on the performance of the alloy.

[0073] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A high-strength, high-conductivity Cu-Cr-Mg-Si alloy material, characterized in that, The alloy comprises the following components, by weight percentage: Cr 0.65%–1.15%, Mg 0.15%, Si 0.02%, with the balance being Cu.

2. The high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 1, characterized in that, The alloy has a Cr content of 1% to 1.15%.

3. A method for preparing a high-strength, high-conductivity Cu-Cr-Mg-Si alloy material, characterized in that, The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to any one of claims 1 to 2 comprises the following steps: (1) Melt and cast to obtain ingots; (2) Homogenization treatment; (3) Hot rolling deformation; (4) Solution treatment; (5) Pre-aging treatment; (6) First cold rolling deformation; (7) Second time limit processing; (8) Second cold rolling deformation; (9) A third aging treatment is performed to obtain the alloy.

4. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In step (1), the melting temperature is 1200℃~1400℃ and the holding time is 3~10min.

5. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In step (2), the homogenization temperature is 900℃~960℃, and charcoal is placed in the furnace to prevent oxidation.

6. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In step (3), the furnace is cooled to 900°C before hot rolling, and the deformation is 60% to 80%.

7. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In step (4), the solution treatment temperature is 900℃~960℃, the holding time is 1~2h, and water quenching is used for cooling.

8. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In steps (5) and (9), the pre-aging and third aging temperatures are both 400℃~500℃, the time is 1~12h, and water quenching is used for cooling.

9. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In steps (6) and (8), the cold rolling temperature is room temperature, and the deformation is 40% to 60%.

10. The method for preparing the high-strength, high-conductivity Cu-Cr-Mg-Si alloy material according to claim 3, characterized in that, In step (7), the second aging temperature is 450℃ and the time is 1 to 12 hours.

Images