A high-strength, high-impact toughness graphene-reinforced copper-based composite material and a method for preparing the same

Abstract

The present application relates to a kind of high-strength, high impact toughness graphene reinforced copper-based composite material and its preparation method, the composite material is obtained by graphene and copper silver alloy composite, composite material contains the discontinuous desolvation organization of volume percentage content 38~86%, discontinuous desolvation organization is mainly composed of sub-micron scale Ag particle and Cu-rich matrix phase, part Ag particle is nanometer scale rod and densely distributed in discontinuous desolvation organization.In room temperature condition, the graphene reinforced copper-based composite material provided by the present application reaches 700~900MPa in tensile strength, elastic modulus is 125~138GPa, conductivity reaches 84~93%IACS, its linear expansion coefficient is 11.0×10 ‑6 ~12.5×10 ‑6 ℃ ‑1 At 20 DEG C, impact toughness is 80~110J·cm ‑2 , and the comprehensive performance is excellent.

Description

Technical Field

[0001] This invention belongs to the field of copper or copper-based alloy technology, specifically relating to a graphene-reinforced copper-based composite material with high strength and high impact toughness and its preparation method. Background Technology

[0002] Industrial pure copper possesses excellent plasticity and superior electrical and thermal conductivity, making it an important functional-structural integrated material widely used in electronics, instrumentation, and high-intensity magnetic fields. However, its relatively low strength significantly limits its applications. For example, in high-intensity magnetic fields, copper-based materials, as strong magnetic conductors, require excellent strength, toughness, and conductivity at both room temperature and ambient temperature. Industrial pure copper cannot meet these performance requirements. Currently, methods to improve the strength of industrial pure copper mainly involve alloying and plasticity processing. On one hand, introducing alloying elements into pure copper produces solid solution strengthening and dispersion strengthening effects, thereby improving the material's strength and hardness. On the other hand, plasticity processing introduces dislocations or refines grains to enhance dislocation strengthening and grain refinement. However, both methods, while increasing the strength of copper-based materials, reduce their electrical conductivity and fracture toughness. Therefore, how to improve the strength of pure copper while maintaining high electrical conductivity and toughness is currently a research hotspot in copper-based materials.

[0003] Research has found that adding a high-strength reinforcing material that is immiscible with Cu to pure copper can produce copper-based composite materials with high strength and high conductivity. The immiscibility of the reinforcing material with copper ensures the high purity of the copper matrix, thus giving the composite material high conductivity. Furthermore, the addition of a high-hardness reinforcing material introduces high-hardness particles into the pure copper, effectively hindering dislocation movement and improving the material's strength.

[0004] Graphene, with its stable structure, is one of the hardest materials in the world. Furthermore, it possesses excellent electrical and thermal conductivity, making it a highly promising reinforcement material for metal-based composites. However, effectively combining Cu (Cu) with graphene to ensure uniform graphene distribution within the composite material remains a challenge in developing graphene-reinforced copper-based composites. Currently, the main methods for preparing graphene-reinforced copper-based composites include chemical vapor deposition (CVD) and casting. CVD is difficult to use for preparing large-sized composites, while casting produces composites with poor microstructure uniformity and density. Therefore, developing an efficient processing method for large-sized copper-based composites and addressing the issue of graphene uniformity in graphene-reinforced copper-based composites is a crucial technical challenge that needs to be solved in preparing high-strength, high-conductivity, and high-impact-toughness graphene-reinforced copper-based composites. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a graphene-reinforced copper-based composite material and its preparation method. Using a copper-silver alloy (Cu-Ag alloy) as the matrix and graphene as the reinforcement, the graphene-reinforced copper-based composite material obtained by optimizing the composition design and processing method has high strength, high conductivity and high impact toughness, which can meet the performance requirements of lead frame and ultra-strong magnetic field magnet materials.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] A high-strength, high-impact-toughness graphene-reinforced copper-based composite material is provided, which is obtained by combining graphene with copper-silver alloy. The composite material contains a discontinuous desolvation structure with a volume percentage of 38-86%. The discontinuous desolvation structure is mainly composed of submicron-scale Ag particles and Cu-rich matrix phase. Some Ag particles are rod-shaped with a diameter of nanometer scale and are densely distributed in the discontinuous desolvation structure.

[0008] According to the above scheme, the copper-silver alloy grain size in the composite material is 0.4-5 μm, and the mass fraction of graphene is 0.01-0.08 wt.%.

[0009] According to the above scheme, the elemental composition and mass percentage of the copper-silver alloy are as follows: silver 24-30 wt.%, erbium 0.05-0.3 wt.%, dysprosium 0.05-0.3 wt.%, with the remainder being Cu and unavoidable impurities; the mass ratio of erbium to dysprosium is 0.25-4:1, and the total content of erbium and dysprosium does not exceed 0.4 wt.%.

[0010] The present invention also includes a method for preparing the above-mentioned high-strength, high-impact-toughness graphene-reinforced copper-based composite material, the specific steps of which are as follows:

[0011] Step 1: Evenly lay a layer of graphene on the surface of the copper-silver alloy plate, and then place another copper-silver alloy plate of the same specifications on it to form a three-layer stacked plate.

[0012] Step 2: The three-layer stacked plates obtained in Step 1 are rolled on a rolling mill to obtain a rolled plate.

[0013] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment. Then cut the rolled sheet into two composite sheets of the same size. Then straighten, pickle, dehydrate and dry the composite sheets in sequence. Then stack the two composite sheets together and evenly lay a layer of graphene in the middle to obtain a three-layer stacked sheet.

[0014] Step 4: Repeat steps 2 and 3 6 to 16 times to obtain a multilayer graphene / copper composite board. Then, the obtained multilayer graphene / copper composite board is stacked and rolled on a rolling mill and heat-treated again. Subsequently, the obtained composite board is subjected to friction stirring (to eliminate defects such as shrinkage porosity and shrinkage cavities in the product and to achieve graphite homogenization) and grinding (to eliminate surface defects). Finally, it is cold rolled to obtain a graphene-reinforced copper-based composite material.

[0015] According to the above scheme, the oxygen content of the copper-silver alloy plate in step one shall not exceed 30 ppm and the sulfur content shall not exceed 50 ppm.

[0016] According to the above scheme, the graphene mentioned in steps one and three is multilayer graphene, with 3 to 7 layers, and the amount of graphene deposited on the copper plate surface is 0.1 to 1.2 mg / cm². 2 .

[0017] According to the above scheme, the processing rate of single-pass rolling in step two is 46-60%, and the rolling speed is 2-50 mm / s.

[0018] According to the above scheme, the heat treatment process conditions for step three are: under hydrogen or nitrogen protection, holding at 280–500℃ for 1–8 hours. The purpose of this heat treatment is to eliminate the work hardening effect of the material, facilitating subsequent rolling.

[0019] According to the above scheme, the conditions for the step four overlay rolling process are: rolling speed of 2 to 50 mm / s and reduction rate of not less than 50%.

[0020] According to the above scheme, the conditions for the second heat treatment in step four are: under hydrogen or nitrogen protection, hold at 200–400°C for 1–2 hours. The purpose of this heat treatment is to eliminate residual stress in the material.

[0021] According to the above scheme, during the friction stirring process in step four, the moving speed of the stirring head is 0.5 to 10 mm / s, and air cooling is used to cool the composite board so that the temperature of the bottom of the composite board does not exceed 500℃.

[0022] According to the above scheme, the cold rolling rate in step four is 10-40%. At this time, the role of cold rolling is to further improve the strength of the composite material by introducing dislocations.

[0023] This invention also includes the application of the aforementioned high-strength, high-impact-toughness graphene-reinforced copper-based composite material in integrated circuits and high-strength magnetic field materials. It is mainly used in the fabrication of lead frames for integrated circuits, ultra-strong magnetic field magnets, etc.

[0024] This invention uses a Cu-Ag alloy with specific components to replace pure copper, improving the overall performance of copper-based composite materials. This Cu-Ag alloy exhibits excellent electrical and thermal conductivity. By controlling the heat treatment process of the composite material, an aging reaction is induced, increasing the Ag phase content in the Cu-Ag alloy and effectively improving its conductivity. During the aging reaction, the Ag phase precipitates through either continuous or discontinuous precipitation. The short rod-shaped Ag particles formed by discontinuous precipitation effectively increase the Cu / Ag phase interface, which is beneficial for improving the alloy's fracture toughness. However, in typical solid solution and aging reactions, the rate of discontinuous precipitation is slow, and the precipitated silver phase tends to coarsen during prolonged aging, making it difficult to simultaneously achieve high strength and high conductivity. This invention significantly increases the volume fraction of nanometer-diameter rod-shaped silver particles formed by discontinuous precipitation in the composite material by adding appropriate amounts of dysprosium and erbium, thereby achieving high strength and high conductivity in the composite material.

[0025] This invention employs a cumulative rolling method combined with friction stir processing to achieve the composite of graphene and Cu-Ag alloy, preparing a graphene / Cu-Ag alloy composite material. By adding erbium and dysprosium elements to the copper matrix and controlling annealing and friction stir parameters, a discontinuous desolvation and precipitation reaction is promoted, resulting in the formation of high-density short rod-shaped Ag phase particles in the Cu-Ag alloy matrix.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. This invention promotes the discontinuous desolvation reaction of copper-silver (Cu-Ag) alloy during annealing by adding appropriate amounts of erbium and dysprosium, increases the volume fraction of discontinuous desolvation structure in the alloy, and increases the number of submicron-scale short rod-shaped Ag phase particles generated by the discontinuous desolvation reaction, effectively improving the strength and impact toughness of the material under room temperature and low temperature (77K) conditions.

[0028] 2. This invention employs a cumulative rolling method combined with friction stir processing to uniformly incorporate high-strength, high-modulus graphene into a copper-silver alloy, thus achieving the preparation of graphene-reinforced copper-based composite materials. The resulting graphene-reinforced copper-based composite material comprises graphene and nanofiber-like Ag phase particles as the reinforcing phase, achieving two-phase hybrid reinforcement of graphene / Ag particles. This improves the coefficient of linear expansion, strength, and elastic modulus of the copper-based composite material, and refines the grain size of the copper-silver alloy matrix. Simultaneously, dislocations are introduced into the copper-silver alloy matrix, resulting in superior mechanical properties. The graphene-reinforced copper-based composite material provided by this invention exhibits excellent performance in terms of strength, impact toughness, conductivity, and dimensional stability. At room temperature, it achieves a tensile strength of 700–900 MPa, an elastic modulus of 125–138 GPa, and a conductivity of 84–93% IACS. Its coefficient of linear expansion at 20°C is 11.0 × 10⁻⁶. -6 ~12.5×10 -6 ℃ -1 Impact toughness is 80–110 J·cm -2 At a temperature of 77K, its tensile strength reaches 820–1010 MPa, resistivity reaches 0.71–0.74 μΩ·cm, and impact toughness is 110–146 J·cm. -2 It has excellent overall performance. Attached Figure Description

[0029] Figure 1 This is a longitudinal section SEM image of the graphene-reinforced copper-based composite material sheet prepared in Example 1 of the present invention before friction stir processing;

[0030] Figure 2 This is a TEM image of the graphene-reinforced copper-based composite material prepared in Example 1;

[0031] Figure 3 This is a SEM image of the graphene-reinforced copper-based composite material sheet prepared in Example 3 before friction stir processing;

[0032] Figure 4 This is a TEM image of the graphene-reinforced copper-based composite material prepared in Example 3. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] The copper-silver alloy plates used in the comparative examples and embodiments of this invention have an oxygen content of no more than 30 ppm and a sulfur content of no more than 50 ppm; the graphene used is multilayer graphene with 3 to 7 layers.

[0035] The comparative examples and embodiments of this invention test the volume fraction of discontinuous desolvated tissue in SEM images according to the grid cut-out method in GB / T15749-2008 Quantitative Metallographic Determination Method.

[0036] Comparative Example 1

[0037] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0038] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top, forming a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26 wt.%.

[0039] The remainder consists of Cu and unavoidable impurities;

[0040] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0041] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0042] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is applied during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 3.2 μm, and the volume fraction of discontinuous desolvation structure is 6%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0043] The graphene-reinforced copper-based composite material prepared in this comparative example exhibits the following properties at room temperature: tensile strength of 664 MPa, elastic modulus of 128 GPa, conductivity of 82% IACS, resistivity of 2.103 μΩ·cm, and impact toughness of 56 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.6 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 728MPa, its low-temperature resistivity is 0.756μΩ·cm, and its low-temperature impact toughness is 74J·cm. -2 .

[0044] Comparative Example 2

[0045] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0046] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26wt.%, erbium content 0.1wt.%, and the remainder is Cu and unavoidable impurities.

[0047] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0048] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0049] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is applied during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 3.1 μm, and the volume fraction of discontinuous desolvation structure is 6%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0050] The graphene-reinforced copper-based composite material prepared in this comparative example exhibits the following properties at room temperature: tensile strength of 656 MPa, elastic modulus of 128 GPa, electrical conductivity of 82.4% IACS, resistivity of 2.092 μΩ·cm, and impact toughness of 58 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.6 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 720MPa, its low-temperature resistivity is 0.754μΩ·cm, and its low-temperature impact toughness is 74J·cm. -2 .

[0051] Comparative Example 3

[0052] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0053] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26wt.%, dysprosium content 0.1wt.%, and the remainder is Cu and unavoidable impurities.

[0054] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0055] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0056] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. Then, the obtained composite plate is subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing through the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 3.4 μm, and the volume fraction of discontinuous desolvation structure is 9%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0057] The graphene-reinforced copper-based composite material prepared in this comparative example exhibits the following properties at room temperature: tensile strength of 670 MPa, elastic modulus of 128 GPa, electrical conductivity of 82.5% IACS, resistivity of 2.090 μΩ·cm, and impact toughness of 64 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.5 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 742MPa, its low-temperature resistivity is 0.748μΩ·cm, and its low-temperature impact toughness is 79J·cm. -2 .

[0058] Example 1

[0059] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0060] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26wt.%, erbium content 0.2wt.%, dysprosium content 0.1wt.%, and the remainder is Cu and unavoidable impurities.

[0061] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0062] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0063] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite sheet. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite sheet is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite sheet with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. The obtained composite sheet is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite sheet at a moving speed of 8 mm / s, passing over the entire surface of the composite sheet. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite sheet does not exceed 350℃. After the friction stir processing is completed, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, cold rolling is performed with a cold rolling processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0064] like Figure 1 The image shows a longitudinal section SEM image of the graphene-reinforced copper-based composite material sheet prepared in this embodiment before friction stir processing. The image reveals a significant discontinuous desolvation reaction within the copper phase. The discontinuous desolvation structure formed by this reaction mainly consists of submicron-scale Ag phase particles and a Cu-rich matrix phase. The discontinuous desolvation structure exhibits a low Cu phase solute atom content and a clear difference in brightness and darkness compared to the Cu phase without the discontinuous desolvation reaction. At this point, the volume fraction of the discontinuous desolvation structure in the composite material is approximately 38%.

[0065] like Figure 2The image shown is a TEM image of the graphene-reinforced copper-based composite material prepared in this embodiment. As can be seen from the image, the composite material is composed of fine grains. The average grain size of the copper-silver alloy grains in the composite plate is 2.7 μm. Short rod-shaped Ag particles can be observed inside some grains. The Ag particles have a length of submicron and an average diameter of about 70 nm.

[0066] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 734 MPa, elastic modulus of 128 GPa, conductivity of 84.2% IACS, resistivity of 2.048 μΩ·cm, and impact toughness of 92 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.4 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 822MPa, its low-temperature resistivity is 0.740μΩ·cm, and its low-temperature impact toughness is 134J·cm. -2 .

[0067] Example 2

[0068] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0069] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 28wt.%, erbium content 0.15wt.%, dysprosium content 0.1wt.%, and the remainder is Cu and unavoidable impurities.

[0070] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0071] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 480℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0072] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. Then, the obtained composite plate is subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing through the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 2.1 μm, and the volume fraction of discontinuous desolvation structure is 57%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0073] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 796 MPa, elastic modulus of 130 GPa, conductivity of 86.7% IACS, resistivity of 1.989 μΩ·cm, and impact toughness of 97 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.4 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 879MPa, its low-temperature resistivity is 0.728μΩ·cm, and its low-temperature impact toughness is 122J·cm. -2 .

[0074] Example 3

[0075] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0076] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 28wt.%, erbium content 0.1wt.%, dysprosium content 0.15wt.%, and the remainder is Cu and unavoidable impurities.

[0077] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0078] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment, holding it at 400℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0079] Step 4: Repeat steps 2 to 3 11 times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 300℃ for 1 hour under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing is completed, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, cold rolling is performed with a cold rolling processing rate of 30% to obtain a graphene-reinforced copper-based composite material with a thickness of 2.66 mm.

[0080] like Figure 3 The image shown is a SEM image of the graphene-reinforced copper-based composite material sheet prepared in this embodiment before friction stir processing. The image reveals a significant discontinuous desolvation reaction in the copper phase, with numerous elongated Ag particles densely distributed within the discontinuous desolvation structure. At this point, the volume fraction of the discontinuous desolvation structure in the composite material significantly increases, reaching approximately 84%.

[0081] like Figure 4 The image shown is a TEM image of the graphene-reinforced copper-based composite material prepared in this embodiment. As can be seen from the image, the composite material is mainly composed of fine grains. The average grain size of the copper-silver alloy grains in the composite plate is 1.6 μm. A large number of short rod-shaped Ag phase particles can be observed inside some grains.

[0082] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 892 MPa, elastic modulus of 134 GPa, conductivity of 91.4% IACS, resistivity of 1.886 μΩ·cm, and impact toughness of 109 J·cm. -2 Its coefficient of linear expansion at 20℃ is 11.6 × 10⁻⁶. -6 ℃ -1At a temperature of 77K, its low-temperature tensile strength is 1002 MPa, its low-temperature resistivity is 0.711 μΩ·cm, and its low-temperature impact toughness is 141 J·cm. -2 .

[0083] Example 4

[0084] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0085] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (5mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.25mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: 30 wt.% silver, 0.2 wt.% erbium, 0.2 wt.% dysprosium, and the remainder is Cu and unavoidable impurities.

[0086] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 5 mm.

[0087] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment, holding it at 400℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.25 mg / cm³. 2 This results in three stacked layers of boards;

[0088] Step 4: Repeat steps 2 and 3 nine times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 5 mm. It is then heat-treated again at 300℃ for 2 hours under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 2.2 μm, and the volume fraction of discontinuous desolvation structure is 71%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 30% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.36 mm.

[0089] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 812 MPa, elastic modulus of 131 GPa, conductivity of 85.8% IACS, resistivity of 2.009 μΩ·cm, and impact toughness of 106 J·cm. -2 Its coefficient of linear expansion at 20℃ is 11.4 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 925MPa, its low-temperature resistivity is 0.736μΩ·cm, and its low-temperature impact toughness is 138J·cm. -2 .

[0090] Example 5

[0091] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0092] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26wt.%, erbium content 0.15wt.%, dysprosium content 0.15wt.%, and the remainder is Cu and unavoidable impurities.

[0093] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0094] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0095] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 3.5 μm, and the volume fraction of discontinuous desolvation structure is 67%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0096] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 785 MPa, elastic modulus of 129 GPa, conductivity of 88.7% IACS, resistivity of 1.944 μΩ·cm, and impact toughness of 102 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.4 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 898MPa, its low-temperature resistivity is 0.722μΩ·cm, and its low-temperature impact toughness is 129J·cm. -2 .

[0097] Example 6

[0098] The specific steps of the preparation method for a graphene-reinforced copper-based composite material are as follows:

[0099] Step 1: Evenly lay a layer of graphene on the surface of a copper-silver alloy plate (4mm thick, 100mm long, and 30mm wide), with a graphene coverage of 0.2mg / cm³. 2 Then, another copper-silver alloy plate of the same specifications is placed on top to form a three-layer stacked plate. The composition of the copper-silver alloy is: silver content 26wt.%, erbium content 0.1wt.%, dysprosium content 0.2wt.%, and the remainder is Cu and unavoidable impurities.

[0100] Step 2: The three-layer stacked plates obtained in Step 1 are stacked and rolled on a rolling mill at a rolling speed of 5 mm / s. The single-pass stacking rate is 50%, resulting in a stacked plate with a thickness of 4 mm.

[0101] Step 3: Place the rolled sheet obtained in Step 2 into a heating furnace for heat treatment at 350℃ for 2 hours under nitrogen protection. Then, cut the rolled sheet into two composite sheets of the same size. The composite sheets are then subjected to straightening, pickling, dehydration, and drying processes in sequence. Finally, the two composite sheets are stacked together, and a layer of graphene is evenly laid in the middle, with a graphene layer density of 0.2 mg / cm³. 2 This results in three stacked layers of boards;

[0102] Step 4: Repeat steps 2 and 3 eight times to obtain a multilayer graphene / copper composite plate. The processing rate of each pass is 50%. Then, the obtained multilayer graphene / copper composite plate is rolled on a rolling mill at a rolling speed of 5 mm / s and a reduction rate of 50% to obtain a composite plate with a thickness of 4 mm. It is then heat-treated again at 350℃ for 1 hour under hydrogen protection. The obtained composite plate is then subjected to friction stir processing. During the processing, the stirring head moves along the surface of the composite plate at a moving speed of 8 mm / s, passing over the entire surface of the composite plate. Air cooling is added during the stirring process to ensure that the temperature of the lower surface of the composite plate does not exceed 350℃. After the friction stir processing, the average grain size of copper grains in the composite plate is 3.2 μm, and the volume fraction of discontinuous desolvation structure is 86%. Then, the material is ground by 0.1 mm on both the upper and lower surfaces to eliminate surface defects. Finally, it is cold rolled with a processing rate of 20% to obtain a graphene-reinforced copper-based composite material with a thickness of 3.04 mm.

[0103] The graphene-reinforced copper-based composite material prepared in this embodiment exhibits the following properties at room temperature: tensile strength of 816 MPa, elastic modulus of 129 GPa, conductivity of 91.8% IACS, resistivity of 1.878 μΩ·cm, and impact toughness of 110 J·cm. -2 Its coefficient of linear expansion at 20℃ is 12.4 × 10⁻⁶. -6 ℃ -1 At a temperature of 77K, its low-temperature tensile strength is 964MPa, its low-temperature resistivity is 0.708μΩ·cm, and its low-temperature impact toughness is 146J·cm. -2 .

[0104] The phase parameters and performance test results of the graphene-reinforced copper-based composite materials prepared in the comparative examples and examples are shown in Table 1.

[0105] Table 1

[0106]

[0107] The dislocation density of the graphene-reinforced copper-based composite material of this invention is closely related to the KAM (Kernel Average Misorientation) value in the electron backscatter diffraction (EBSD) results, and the KAM value can reflect the dislocation density in the material. The KAM value is directly proportional to the dislocation density within the material grains. During EBSD sample analysis, the scan step size is 0.5 μm.

[0108] As can be seen from Table 1, compared with Comparative Examples 1-3, the volume fraction of discontinuous desolvation tissue in the graphene-reinforced copper-based composite materials prepared in Examples 1-6 was significantly increased, indicating that the addition of appropriate amounts of dysprosium and erbium played a major role.

Claims

1. A high-strength, high-impact toughness graphene-reinforced copper-based composite material, characterized by, The graphene / copper-silver alloy composite material contains discontinuous precipitated structures with a volume percentage of 38-86%, and the discontinuous precipitated structures are mainly composed of sub-micron Ag particles and Cu-rich matrix phase, and some Ag particles are nanometer-sized rods and densely distributed in the discontinuous precipitated structures. The copper-silver alloy contains 24-30 wt.% of silver, 0.05-0.3 wt.% of erbium, and 0.05-0.3 wt.% of dysprosium, and the rest is Cu and inevitable impurities; the mass ratio of erbium to dysprosium is 0.25-4:1, and the total content of erbium and dysprosium is not more than 0.4 wt.%. The grain size of the copper-silver alloy in the composite material is 0.4-5 μm, and the mass fraction of graphene is 0.01-0.08 wt.%.

2. A method of producing the high-strength, high-impact-toughness graphene-reinforced copper-based composite material according to claim 1, characterized by, The specific steps are as follows: Step one, uniformly lay a layer of graphene on the surface of the copper-silver alloy plate, and then place another copper-silver alloy plate of the same size to form a three-layer stacked plate; Step two, stack the three-layer stacked plate obtained in step one on a rolling mill to obtain a stacked plate; Step three, place the stacked plate obtained in step two in a heating furnace for heat treatment, then cut the stacked plate into two composite plates of the same size, and then sequentially perform straightening, pickling, dehydration and drying treatment on the composite plates, then stack the two composite plates, and uniformly lay a layer of graphene in the middle to obtain a three-layer stacked plate; Step four, repeat steps two and three for 6-16 times to obtain a multi-layer graphene / copper composite plate, then stack the obtained multi-layer graphene / copper composite plate on a rolling mill and heat treat again, then sequentially perform friction stir processing and grinding processing on the obtained composite plate, and finally perform cold rolling to obtain a graphene reinforced copper-based composite material.

3. The method of producing high-strength, high-impact toughness graphene-reinforced copper-based composites according to claim 2, characterized in that, The copper-silver alloy plate in step one has an oxygen content of not more than 30 ppm and a sulfur content of not more than 50 ppm; the graphene in step one and step three is multilayer graphene, the number of graphene layers is 3-7 layers, and the graphene laying amount on the surface of the copper plate is 0.1-1.2 mg / cm 2 .

4. The method of claim 2, wherein the graphene-reinforced copper-based composite material has a high strength and a high impact toughness. In step two, the single-pass stacking rate is 46-60%, and the rolling speed is 2-50 mm / s.

5. The method of producing high strength, high impact toughness graphene-reinforced copper-based composites according to claim 2, characterized in that, In step three, the heat treatment process conditions are as follows: under the protection of hydrogen or nitrogen, the temperature is 280-500 ℃, and the holding time is 1-8 h.

6. The method of producing high strength, high impact toughness graphene-reinforced copper-based composites according to claim 2, characterized in that, In step four, the rolling speed is 2-50 mm / s, and the reduction is not less than 50%; in step four, the heat treatment process conditions are as follows: under the protection of hydrogen or nitrogen, the temperature is 200-400 ℃, and the holding time is 1-2 h.

7. The method of producing high strength, high impact toughness graphene-reinforced copper-based composites according to claim 2, characterized in that, In step four, the stirring head moves at a speed of 0.5-10 mm / s, and the composite plate is cooled by air cooling to keep the bottom temperature of the composite plate below 500 ℃; in step four, the cold rolling rate is 10-40%.

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