Mo2C / Zr synergistically reinforced high-performance copper-based composite material and preparation method thereof

Abstract

The invention discloses a Mo2C / Zr synergistically reinforced high-performance copper-based composite material and a preparation method thereof, and belongs to the technical field of metal-based composite materials. The high-performance copper-based composite material comprises the following components in percentage by mass: more than 0 and less than or equal to 7 percent of Mo2C powder, more than or equal to 0 and less than or equal to 3 percent of Zr powder and the balance of Cu powder. By adding Mo2C, on the basis of ensuring the conductivity of the copper-based composite material, the strength of the composite material is remarkably improved, so that the copper-based composite material has excellent comprehensive performance, meanwhile, by adding the Zr element, the grain boundary diffusivity is inhibited, composite material grains are refined, accumulation of dislocations on a Cu and Mo2C interface is effectively reduced, and the conductivity of the copper-based composite material is improved. And therefore, the reinforcement phase can give full play to the reinforcement effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal matrix composites, and relates to a high-performance copper matrix composite material synergistically strengthened by Mo2C / Zr and a preparation method thereof. Background Art

[0002] Copper and its alloys have good formability, relatively high electrical and thermal conductivities, and are widely used in electrical components and other electrical-related industries. In addition, the demand for advanced copper alloys with high mechanical properties and high-temperature stability in the fields of aerospace, fusion energy reactors, and high-speed railways is also increasing day by day. However, the strength of copper-based materials is usually low, which restricts their practical applications to a certain extent and cannot meet the increasingly stringent application requirements. By adding reinforcing phases to copper-based materials, copper-based materials with higher strength can be obtained. However, adding reinforcing phases easily leads to a decrease in the electrical conductivity of copper-based materials. Therefore, although the mechanical properties of copper-based materials are improved, their electrical properties are reduced, which also greatly limits the practical applications of copper-based materials.

[0003] Therefore, it is necessary to provide a high-performance copper matrix composite material synergistically strengthened by Mo2C / Zr and a preparation method thereof, which can effectively improve the strength of copper-based materials while avoiding the decrease in their electrical conductivity, so that the copper matrix composite material has excellent comprehensive properties and meets higher application requirements. Summary of the Invention

[0004] In order to overcome the problems in the background art, the present invention adds Mo2C to the copper-based material to significantly improve the strength of the copper-based material. The crystal structure of molybdenum carbide is hexagonal, with a high melting point (2690 °C), high hardness (1500 HV), excellent elastic modulus (533 GPa), low resistivity (7.1×10 -7 Ω·m), excellent wear resistance and high-temperature resistance. Therefore, Mo2C as a particulate reinforcement can significantly improve the mechanical properties of copper-based materials, and Mo2C particles will not significantly reduce the electrical conductivity of copper matrix composites. In addition, Mo2C can also effectively inhibit the grain growth of copper-based materials and has a significant promoting effect on the high-temperature mechanical properties of copper matrix composites.

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] On the one hand, the present invention provides a high-performance copper matrix composite material, and the components of the high-performance copper matrix composite material by mass fraction include: 0 < Mo2C powder ≤ 7%, 0 ≤ Zr powder ≤ 3%, and the balance is Cu powder.

[0007] On the other hand, the present invention provides a preparation method of the above high-performance copper matrix composite material, and the preparation method includes the following steps:

[0008] (1) High-energy ball milling: Weigh Zr powder, Mo₂C powder and Cu powder according to the component mass fractions of the copper-based composite material. Perform high-energy ball milling on the mixed powder of Zr powder, Mo₂C powder and Cu powder and filter it to obtain the composite powder;

[0009] (2) Vacuum drying: Perform vacuum drying on the composite powder obtained in the step (1) to obtain the dried copper-based composite powder;

[0010] (3) Sintering and forming: Perform rapid hot pressing sintering on the copper-based composite powder obtained in the step (2) to obtain the sintered copper-based composite material;

[0011] (4) Solution treatment: Perform solution treatment on the sintered copper-based composite material obtained in the step (3);

[0012] (5) Cold rolling: Perform cold rolling on the composite material after solution treatment in the step (4) to obtain the high-performance copper-based composite material.

[0013] Preferably, in the step (1), the ball-to-material ratio is 8:1, the ball milling speed is 200 - 300 rmp, and the ball milling time is 8 - 10 h.

[0014] Preferably, in the step (2), the vacuum drying temperature is 60 - 80 °C, and the drying time is 8 - 10 h.

[0015] Preferably, in the step (3), the sintering vacuum degree < 10 Pa, the sintering temperature is 800 - 1000 °C, the holding time is 10 - 20 min, and the sintering pressure is 30 - 50 MPa.

[0016] Preferably, in the step (4), the solution temperature is 800 - 1000 °C, and the holding time is 1 - 2 h.

[0017] Preferably, in the step (5), the cold rolling reduction is 30 - 50%.

[0018] Advantages of the present invention:

[0019] 1. By adding Mo₂C as the particle reinforcement phase to the copper-based material, the present invention reduces the thermal mismatch of the copper-based composite material and inhibits the grain growth in the copper-based material on the basis of not significantly affecting the electrical conductivity of the copper-based material, so that the copper-based composite material has excellent mechanical properties and electrical properties, thereby improving the comprehensive performance of the copper-based composite material.

[0020] 2. The strengthening effect of the Mo2C reinforcing phase is proportional to its grain size. The smaller the grain size of the reinforcing phase, the better its strengthening effect. However, as the particle size of the reinforcing phase decreases, its surface activity increases, making it prone to agglomeration in the matrix to form larger agglomerates, resulting in poor wettability between the reinforcing phase and the matrix and unstable interfacial bonding, thus causing the reinforcing phase to not fully exert its strengthening effect. In the present invention, by adding Zr element, the grain boundary diffusion rate is inhibited, the grains of the composite material are refined, the grain boundary area of the matrix is increased, and the accumulation of dislocations at the Cu and Mo2C interfaces is effectively reduced, so that the reinforcing phase can more fully exert its strengthening effect.

[0021] 3. The Mo2C reinforcing phase is prone to agglomeration to form larger agglomerates. During hot pressing sintering, pores may also be generated, affecting the thermal / mechanical properties of the material. In the present invention, by adding Zr element, during hot pressing sintering, the grain boundary diffusion rate is inhibited, thereby restricting grain growth, facilitating grain refinement, delaying the coarsening of the grains of the copper-based composite material, reducing stress concentration during sintering, reducing crack propagation, weakening the negative impact caused by the hard and brittle phase on the composite material, helping to improve the strength of the composite material, and further improving the comprehensive performance of the composite material.

[0022] 4. In the present invention, through high-energy ball milling, Mo2C and Zr are uniformly dispersed in the copper-based material, which helps Mo2C and Zr to fully exert their effects, making the copper-based composite material have relatively excellent comprehensive performance.

[0023] 5. The tensile strength of the copper-based composite material prepared in the present invention can reach 520 MPa, and the conductivity remains at 68.9 IACS.

[0024] 6. The composite material prepared in the present invention has high specific strength and specific stiffness, excellent electrical and thermal conductivity, high anti-softening performance, as well as good corrosion resistance and wear resistance, and has relatively good comprehensive performance.

[0025] 7. The present invention uses rapid hot pressing sintering to prepare the composite material, which takes less time and consumes less energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a scanning micrograph of the microstructure of the copper-based material (Cu powder) of the present invention;

[0027] Figure 2 It is a scanning micrograph of the microstructure of the Mo2C powder of the present invention;

[0028] Figure 3 It is a scanning micrograph of the microstructure of the Zr powder of the present invention;

[0029] Figure 4 It is a room temperature tensile mechanical property curve graph of Examples 1 and 3 and Comparative Examples 1 and 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0031] In the examples and comparative examples of the present invention, chemical reagents not specifically stated were all used for experiments with commercially available analytical purity.

[0032] The compositions of the copper-based composite materials in the examples and comparative examples of the present invention are shown in Table 1.

[0033] Table 1

[0034] Item Cu powder <![CDATA[Mo2C powder]]> Zr powder Example 1 37.2g(93％) 2g(5％) 0.8g(2％) Example 2 37.2g(93％) 2.8g(7％) 0 Example 3 38.4g(96％) 0.4g(1％) 1.2g(3％) Comparative Example 1 40g(100％) 0 0 Comparative Example 2 39.2g(98％) 0 0.8g(2％) Comparative Example 3 37.2g(95％) 2g(5％) 0.8g(2％) Comparative Example 4 37.2g(93％) 2g(5％) 0.8g(2％)

[0035] Example 1

[0036] The copper-based composite material in this example was prepared by the following method:

[0037] (1) Weigh Cu powder, Mo2C powder, and Zr powder as raw materials according to the components in Table 1. Place the raw material powders in a stainless steel ball milling tank, and add 40 ml of anhydrous ethanol to the ball milling tank as a processing control agent. Under the conditions of a ball-to-material ratio of 8:1 and a rotation speed of 300 rmp, perform high-energy ball milling on the raw materials for 10 h to achieve the flakiness of the matrix and the uniform dispersion of the reinforcing phase.

[0038] (2) After the ball milling in step (1) is completed, select a medium-speed qualitative filter paper (maximum pore size 15 - 20 μm, filtration speed 35 - 70 s) for suction filtration to filter out the excess anhydrous ethanol and obtain a composite powder.

[0039] (3) Put the composite powder obtained in step (2) into a vacuum drying oven for drying. Keep the temperature at 60 °C for 8 h to obtain a dried copper-based composite powder.

[0040] (4) Perform rapid hot pressing sintering on the dried copper-based composite powder. The sintering vacuum degree is <10 Pa, the sintering temperature is 900 °C, keep the temperature for 10 min, and the sintering pressure is 50 MPa. Obtain a sintered copper-based composite material with a diameter of 25 mm and a thickness of about 10 mm.

[0041] (5) Perform solution treatment on the sintered copper-based composite material obtained in step (4). The solution treatment temperature is 1000 °C and the time is 1 h to achieve the solution of alloying elements.

[0042] (6) Perform cold rolling on the composite material after solution treatment in step (5). The reduction of the lower roll is 30% to obtain a high-performance copper-based composite material.

[0043] The copper-based composite material prepared in this example was processed by wire cutting into specimens that can be used for tensile testing, and the tensile test was carried out to test its room temperature tensile properties. The results are asFigure 4 As shown by Figure 4 the quantitative results are shown in Table 2.

[0044] Example 2

[0045] The copper-based composite material is prepared by the following method in this example:

[0046] (1) Weigh Cu powder and Mo2C powder as raw materials according to the components in Table 1. Place the raw material powders in a stainless steel ball milling tank, and add 40 ml of absolute ethanol to the ball milling tank as a processing control agent. Under the conditions of a ball-to-material ratio of 8:1 and a rotation speed of 200 rmp, perform high-energy ball milling on the raw materials for 8 h to achieve the flaking of the matrix and the uniform dispersion of the reinforcing phase.

[0047] (2) After the ball milling in step (1) is completed, select a medium-speed qualitative filter paper (maximum pore size 15 - 20 μm, filtration speed 35 - 70 s) for suction filtration to filter out the excess absolute ethanol and obtain the composite powder.

[0048] (3) Put the composite powder obtained in step (2) into a vacuum drying oven for drying. Keep it at 80 °C for 10 h to obtain the dried copper-based composite powder.

[0049] (4) Perform rapid hot pressing sintering on the dried copper-based composite powder. The sintering vacuum is <10 Pa, the sintering temperature is 1000 °C, keep it warm for 15 min, and the sintering pressure is 40 MPa. Obtain a sintered copper-based composite material with a diameter of 25 mm and a thickness of about 10 mm.

[0050] (5) Perform solution treatment on the sintered copper-based composite material obtained in step (4). The solution treatment temperature is 800 °C and the time is 2 h to achieve the solution of alloying elements.

[0051] (6) Perform cold rolling on the composite material after solution treatment in step (5). The reduction of the lower roll is 50% to obtain a high-performance copper-based composite material.

[0052] The copper-based composite material prepared in this example has a slight decrease in tensile strength compared with that in Example 1, and other properties are similar to those of the copper-based composite material in Example 1. The slight decrease in the tensile strength in Example 2 is due to the loss of the function of the Zr element, the decrease in the wettability between Mo2C and the matrix, resulting in unstable interfacial bonding, and the insufficient exertion of the strengthening effect of Mo2C, so that the tensile strength slightly decreases with more Mo2C reinforcing phases.

[0053] Example 3

[0054] The copper-based composite material is prepared by the following method in this example:

[0055] (1) Weigh Cu powder, Mo₂C powder, and Zr powder as raw materials according to the components in Table 1. Place the raw material powders in a stainless-steel ball-milling tank, and add 40 ml of anhydrous ethanol to the ball-milling tank as a processing control agent. Under the conditions of a ball-to-material ratio of 8:1 and a rotation speed of 250 rmp, perform high-energy ball milling on the raw materials for 9 h to achieve the flaking of the matrix and the uniform dispersion of the reinforcing phase.

[0056] (2) After the ball milling in step (1) is completed, select a medium-speed qualitative filter paper (maximum pore size 15 - 20 μm, filtration rate 35 - 70 s) for suction filtration to filter off the excess anhydrous ethanol and obtain the composite powder.

[0057] (3) Put the composite powder obtained in step (2) into a vacuum drying oven for drying. Keep it at 70 °C for 9 h to obtain the dried copper-based composite powder.

[0058] (4) Perform rapid hot pressing sintering on the dried copper-based composite powder. The sintering vacuum degree is <10 Pa, the sintering temperature is 800 °C, keep it warm for 20 min, and the sintering pressure is 30 MPa. Obtain a sintered copper-based composite material with a diameter of 25 mm and a thickness of about 10 mm.

[0059] (5) Perform solution treatment on the sintered copper-based composite material obtained in step (4). The solution treatment temperature is 900 °C and the time is 1.5 h to achieve the solution of alloying elements.

[0060] (6) Perform cold rolling on the composite material after solution treatment in step (5). The reduction in thickness is 40% to obtain a high-performance copper-based composite material.

[0061] Cut the copper-based composite material prepared in this example into specimens suitable for tensile testing by wire cutting, and conduct a tensile test to measure its room-temperature tensile properties. The results are as Figure 4 shown. Quantitative results are obtained as shown in Table 2 through Figure 4

[0062] Comparative Example 1

[0063] This comparative example uses the same method as Example 1 to prepare the copper-based material, with the difference that: this comparative example does not add Mo₂C and Zr.

[0064] Cut the copper-based composite material prepared in this example into specimens suitable for tensile testing by wire cutting, and conduct a tensile test to measure its room-temperature tensile properties. The results are as Figure 4 shown. Quantitative results are obtained as shown in Table 2 through Figure 4

[0065] Comparative Example 2

[0066] ​​This comparative example uses the same method as Example 1 to prepare the copper-based material, with the difference that: Mo2C is not added in this comparative example.

[0067] The tensile strength of the copper-based composite material prepared in this comparative example is shown in Table 2.

[0068] Comparative Example 3

[0069] This comparative example uses the same method as Example 1 to prepare the copper-based material, with the difference that: the ball milling speed in this comparative example is 150 rmp and the sintering temperature is 750 °C.

[0070] The copper-based composite material prepared in this example is processed by wire cutting into a specimen for tensile testing, and its room temperature tensile properties are tested. The results are as Figure 4 shown, and the quantitative results are obtained as shown in Table 2 through Figure 4 .

[0071] Comparative Example 4

[0072] This comparative example uses the same method as Example 1 to prepare the copper-based material, with the difference that: cold rolling is not carried out in this comparative example.

[0073] The tensile strength of the copper-based composite material prepared in this comparative example is shown in Table 2.

[0074] Table 2

[0075] Item Tensile strength at room temperature (MPa) Conductivity (%) Example 1 520.35 68.9 Example 2 372.48 57.5 Example 3 401.52 69.3 Comparative Example 1 241.08 86.7 Comparative Example 2 297.89 77.2 Comparative Example 3 301.78 38.8 Comparative Example 4 391.39 50.0

[0076] It can be seen from Table 2 that, compared with Comparative Example 1, the tensile strength of the copper-based composite material in Example 1 has been significantly improved. Since no reinforcing phase was added in Comparative Example 1, that is, the performance of Comparative Example 1 is the performance of pure copper powder, its strength is relatively low. For the electrical conductivity, there is a slight decrease in Example 1 compared with Comparative Example 1. On the one hand, it shows that the addition of the reinforcing phase will indeed cause a decrease in the electrical conductivity of the copper-based composite material. On the other hand, it shows that the Mo2C reinforcing phase can significantly improve the strength of the copper-based composite material while having a relatively small impact on the electrical conductivity of the copper-based composite material.

[0077] It can be seen from Table 2 that, compared with Comparative Example 2, the tensile strength in Example 1 has been significantly improved. In Comparative Example 2, since Mo2C was not added, the copper-based composite material lost its main reinforcing phase, so the tensile strength decreased significantly.

[0078] It can be seen from Table 2 that, compared with Comparative Example 3, the tensile strength in Example 1 has been significantly improved. In Comparative Example 3, due to the too low ball milling speed, the reinforcing phase was unevenly dispersed. In addition, the sintering temperature was too low, greatly reducing the density of the composite material. Therefore, the tensile strength decreased significantly.

[0079] As can be seen from Table 2, compared with Comparative Example 4, the tensile strength of Example 1 is significantly improved, indicating that cold rolling can significantly increase the tensile strength of the composite material. This is because cold deformation makes the grains refined, reduces the formation of dislocation pile-ups while introducing a large number of dislocations during the deformation process, thereby significantly enhancing the tensile strength of the composite material.

[0080] As can be seen from Table 2, compared with Example 2, the tensile strength of Example 1 is improved more significantly, indicating that adding Zr element can effectively reduce the pile-up of dislocations at the interface between Cu and Mo2C, so that the reinforcing phase can give full play to its strengthening effect.

[0081] Through Figure 1 it can be seen that the particle size of Cu powder is small, in the range of 15 - 50 μm, and the particles are evenly dispersed.

[0082] Through Figure 2 it can be seen that the particle size of Mo2C powder is small, in the range of 1 - 3 μm, and the particles tend to agglomerate.

[0083] Through Figure 3 it can be seen that the particle size of Zr powder is small, in the range of 1 - 3 μm, and the particles tend to agglomerate.

[0084] In summary, by adding Mo2C, on the basis of ensuring that the copper-based composite material has good electrical conductivity, the tensile strength of the copper-based composite material is significantly improved, so that the copper-based composite material has relatively excellent comprehensive performance. At the same time, by adding Zr, the grain boundary diffusion rate is inhibited, the grains of the composite material are refined, the matrix grain boundary area is increased, the pile-up of dislocations at the interface between Cu and Mo2C is effectively reduced, so that the reinforcing phase can give full play to its strengthening effect, improve the utilization rate of the reinforcing phase, and reduce the strengthening cost.

[0085] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A high-performance copper-based composite material, characterized in that: The composition of the high-performance copper-based composite material by mass fraction includes: 0 < Mo2C powder ≤ 7%, 0 ≤ Zr powder ≤ 3%, and the balance is Cu powder.

2. The preparation method of a high-performance copper-based composite material according to claim 1, characterized in that: The preparation method includes the following steps: (1) High-energy ball milling: Weigh Zr powder, Mo2C powder, and Cu powder according to the mass fraction of the copper-based composite material, perform high-energy ball milling on the mixed powder of Zr powder, Mo2C powder, and Cu powder, and filter to obtain a composite powder; (2) Vacuum drying: Perform vacuum drying on the composite powder obtained in step (1) to obtain a dried copper-based composite powder; (3) Sintering and forming: Perform rapid hot pressing sintering on the copper-based composite powder obtained in step (2) to obtain a sintered copper-based composite material; (4) Solution treatment: Perform solution treatment on the sintered copper-based composite material obtained in step (3); (5) Cold rolling: Perform cold rolling on the composite material after solution treatment in step (4) to obtain a high-performance copper-based composite material.

3. The preparation method according to claim 2, wherein: In step (1), the ball-to-material ratio is 8:1, the ball milling speed is 200 - 300 rmp, and the ball milling time is 8 - 10 h.

4. The preparation method according to claim 2, characterized in that: In step (2), the vacuum drying temperature is 60 - 80 °C, and the drying time is 8 - 10 h.

5. The preparation method according to claim 2, characterized in that: In step (3), the sintering vacuum degree is < 10 Pa, the sintering temperature is 800 - 1000 °C, the holding time is 10 - 20 min, and the sintering pressure is 30 - 50 MPa.

6. The preparation method according to claim 2, characterized in that: In step (4), the solution temperature is 800 - 1000 °C, and the holding time is 1 - 2 h.

7. The preparation method according to claim 2, wherein: In step (5), the cold rolling reduction is 30 - 50%.

Images