Grain heterogeneous tungsten-copper composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of metal composite materials, in particular to a grain heterogeneous tungsten-copper composite material and a preparation method and application thereof. The method comprises the following steps that titanium carbide powder and a first part of tungsten powder are subjected to ball milling treatment, and W-TiC composite powder is obtained; the W-TiC composite powder and the first part of copper powder are subjected to ball milling treatment, and nanocrystalline composite powder is obtained; the remaining tungsten powder and the remaining copper powder are subjected to ball milling treatment, and coarse-grain composite powder is obtained; the nanocrystalline composite powder and the coarse grain composite powder are subjected to ball milling treatment, and mixed powder is obtained; and the mixed powder is sintered, and the grain heterogeneous tungsten-copper composite material is obtained. According to the invention, a grain heterostructure composed of a W-phase nanocrystalline area and a coarse grain area is successfully constructed through a step-by-step ball milling-mixed sintering process. By means of the structure, the composite material can still maintain excellent plasticity and high conductivity while having high yield strength.

Description

Technical Field

[0001] This invention relates to the field of metal composite materials technology, and in particular to a grain-heterogeneous tungsten-copper composite material, its preparation method, and its application. Background Technology

[0002] Tungsten-copper (W-Cu) composites, as a typical structural-functional integrated material, combine the high strength and hardness of tungsten with the good electrical and thermal conductivity of copper. They are widely used in the power and electronics industries, including electrical contact materials, resistance welding electrodes, high-voltage switch contacts, and thermal management components. Achieving a synergistic improvement in the mechanical and electrical properties of this type of material has always been a major direction for its development.

[0003] However, in existing technologies, the mechanical and electrical properties of W-Cu composites often exhibit a significant limiting relationship. To improve the mechanical properties of W-Cu composites, alloying, introducing a second phase for strengthening, or refining the microstructure are commonly employed. While adding trace alloying elements or ceramic particles can effectively enhance the mechanical properties of the material, these foreign phases significantly hinder the free movement of electrons, leading to a substantial decrease in electrical conductivity. On the other hand, relying solely on grain refinement for strengthening, although it can improve strength, often results in reduced plasticity and microstructure instability and softening at high temperatures. This mutual constraint between properties severely limits the reliability and service life of W-Cu composites in high-end applications requiring high temperature, high load, and high conductivity.

[0004] Therefore, how to effectively improve the strength, plasticity and high-temperature stability of W-Cu composite materials while maintaining their electrical conductivity has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a grain heterogeneous tungsten-copper composite material, its preparation method, and its application. By designing and constructing a specific heterogeneous structure composed of W-phase nanocrystalline regions and coarse-grained regions, and introducing titanium carbide to transform it in situ into titanium dioxide distributed at the grain boundaries during sintering, the strength, plasticity, conductivity, and high-temperature stability of the material are synergistically improved.

[0006] To achieve the above objectives, the present invention provides a method for preparing a grain-isomorphic tungsten-copper composite material, comprising the following steps: S1. Provides tungsten powder, copper powder and titanium carbide powder; S2. Titanium carbide powder and tungsten powder from the first part are subjected to a first ball milling process to obtain W-TiC composite powder; W-TiC composite powder and copper powder from the first part are subjected to a second ball milling process to obtain nanocrystalline composite powder; S3. The remaining tungsten powder and the remaining copper powder are subjected to a third ball milling process to obtain coarse-grained composite powder; S4. The nanocrystalline composite powder and the coarse-crystalline composite powder are subjected to a fourth ball milling process to obtain a mixed powder; S5. The mixed powder is sintered to obtain a crystalline heterogeneous tungsten-copper composite material.

[0007] Preferably, in S1, the mass ratio of tungsten powder, copper powder and titanium carbide powder is 70-80:25-40:0.05-2.

[0008] Preferably, in S2, the ball-to-material ratio of the first ball milling process is 15-20:1, the rotation speed is 500-600 r / min, and the time is 6-10 h.

[0009] Preferably, in S2, the second ball milling process is carried out under a protective atmosphere, the ball-to-material ratio of the second ball milling process is 10-20:1, the rotation speed is 500-600 r / min, and the time is 3-5 h.

[0010] Preferably, in S3, the third ball milling process is carried out under a protective atmosphere, the ball-to-material ratio of the third ball milling process is 5-8:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

[0011] Preferably, in S4, the fourth ball milling process is carried out under a protective atmosphere, the ball-to-material ratio of the fourth ball milling process is 10-15:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

[0012] Preferably, in S5, the sintering pressure is 80-100MPa, the temperature is 950-980℃, and the holding time is 5-10min.

[0013] Preferably, in S5, the heating rate of the sintering process is 80-100℃ / min, and the vacuum degree of the sintering environment is ≤0.34Pa.

[0014] The present invention also provides a grain-heterogeneous tungsten-copper composite material, which is prepared according to the preparation method of the grain-heterogeneous tungsten-copper composite material.

[0015] The present invention also provides the application of the aforementioned grain-heterogeneous tungsten-copper composite material in the preparation of high-temperature service components for the electrical industry.

[0016] The beneficial effects of this invention are as follows: (1) The present invention provides a method for preparing a grain-heterogeneous tungsten-copper composite material, comprising the following steps: providing tungsten powder, copper powder and titanium carbide powder; subjecting titanium carbide powder and a first portion of tungsten powder to a first ball milling treatment to obtain W-TiC composite powder; subjecting W-TiC composite powder and a first portion of copper powder to a second ball milling treatment to obtain nanocrystalline composite powder; subjecting the remaining tungsten powder and the remaining copper powder to a third ball milling treatment to obtain coarse-grained composite powder; subjecting the nanocrystalline composite powder and the coarse-grained composite powder to a fourth ball milling treatment to obtain mixed powder; subjecting the mixed powder to sintering treatment to obtain a grain-heterogeneous tungsten-copper composite material.

[0017] This invention successfully constructs a grain heterostructure consisting of W-phase nanocrystalline and coarse-grained regions through a "stepwise ball milling-mixed sintering" process. This structure enables the material to achieve high strength in the nanocrystalline region while maintaining good plastic deformation capacity in the coarse-grained region. Furthermore, the heterostructure design effectively reduces the obstruction to electron transport, allowing the composite material to maintain excellent plasticity and high electrical conductivity while possessing high yield strength.

[0018] When the "nanocrystalline-coarse-grained" heterostructure is deformed, a significant strain gradient is formed between the two phase regions. This gradient can induce a back stress strengthening effect, which not only helps maintain the overall strength of the material, but also enhances its work hardening ability. At the same time, the strain gradient promotes the proliferation and movement of geometrically necessary dislocations in the coarse-grained region. These dislocations can coordinate deformation, alleviate local stress concentration, enhance the load transfer efficiency between heterostructure interfaces, and inhibit the initiation and propagation of microcracks.

[0019] (2) This invention creatively introduces trace amounts of nano-TiC, which reacts with oxygen in the powder during sintering, transforming in situ into TiO2 and mainly distributed at the tungsten grain boundaries. This process plays multiple roles simultaneously: the generated TiO2 particles can effectively pin the grain boundaries, not only inhibiting nanocrystal coarsening and stabilizing the heterostructure at room temperature, but also effectively enhancing the anti-migration ability of the grain boundaries at high temperatures, thereby improving the thermal stability of the structure; at the same time, the reaction consumes oxygen impurities at the grain boundaries, alleviating grain boundary embrittlement and helping to improve the plasticity of the material; in addition, the fine TiO2 generated in situ has a weak electron scattering effect, minimizing the impact on conductivity while achieving fine grain strengthening. These aspects work together to synergistically endow the material with excellent room temperature strength, plasticity, conductivity, and outstanding high-temperature softening resistance.

[0020] (3) The preparation method of this invention is based on mature powder metallurgy technology (ball milling, hot pressing sintering), with a clear process route and easy-to-control parameters, without the need for complex equipment or expensive raw materials. By adjusting the mixing ratio of nanocrystalline and coarse-grained powders, the heterogeneous structure characteristics of the final composite material can be easily controlled, thereby obtaining materials that meet different performance requirements (emphasizing strength or remodeling conductivity), with good process flexibility and industrial application prospects. Attached Figure Description

[0021] Figure 1 This is a microscopic morphology diagram of the tungsten-copper composite material with grain heterogeneity in Example 1 of the present invention; Figure 2 This is a microscopic morphology diagram of the tungsten-copper composite material with grain heterogeneity in Example 3 of the present invention; Figure 3 This is a microscopic morphology diagram of the tungsten-copper composite material in Comparative Example 1 of the present invention; Figure 4 This is a microscopic morphology diagram of the tungsten-copper composite material in Comparative Example 2 of the present invention; Figure 5 This is a TEM characterization image of the small-scale W phase region in the composite material of Example 1 of the present invention; Figure 6 This is a diagram showing the presence of Ti at the grain boundaries of the nanocrystalline region in the composite material of Embodiment 1 of the present invention; Figure 6 In the image, 'a' represents the TEM characterization of the TiO2 / W interface. Figure 6 In the diagram, b is the Fast Fourier Transform analysis of TiO2 in a. Figure 6 In the figure, c is the Fast Fourier Transform analysis diagram of the W matrix in a; Figure 7 These are room temperature compressive stress-strain curves of different composite materials of the present invention; Figure 8 This is a graph showing the change in hardness of different composite materials of the present invention with temperature. Detailed Implementation

[0022] This invention provides a method for preparing a tungsten-copper composite material with heterogeneous grains, comprising the following steps: S1. Provides tungsten powder, copper powder and titanium carbide powder; S2. Titanium carbide powder and tungsten powder from the first part are subjected to a first ball milling process to obtain W-TiC composite powder; W-TiC composite powder and copper powder from the first part are subjected to a second ball milling process to obtain nanocrystalline composite powder; S3. The remaining tungsten powder and the remaining copper powder are subjected to a third ball milling process to obtain coarse-grained composite powder; S4. The nanocrystalline composite powder and the coarse-crystalline composite powder are subjected to a fourth ball milling process to obtain a mixed powder; S5. The mixed powder is sintered to obtain a crystalline heterogeneous tungsten-copper composite material.

[0023] In this invention, in S1, the mass ratio of tungsten powder, copper powder and titanium carbide powder is 70-80:25-40:0.05-2.

[0024] In this invention, in S1, the particle size of tungsten powder is 10-14 μm; the particle size of copper powder is 0.5-2 μm; and the particle size of titanium carbide powder is ≤100 nm.

[0025] In this invention, in S2, the ball-to-material ratio of the first ball milling process is 15-20:1, the rotation speed is 500-600 r / min, and the time is 6-10 h.

[0026] In this invention, in S2, the second ball milling process is carried out under a protective atmosphere, which is selected from argon; the ball-to-material ratio of the second ball milling process is 10-20:1, the rotation speed is 500-600 r / min, and the time is 3-5 h.

[0027] In this invention, in S3, the third ball milling process is carried out under a protective atmosphere, which is selected from argon; the ball-to-material ratio of the third ball milling process is 5-8:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

[0028] In this invention, in S4, the mass ratio of nanocrystalline composite powder to coarse-crystalline composite powder is 15-25.5:4.5-15.

[0029] In this invention, in S4, the fourth ball milling process is carried out under a protective atmosphere, which is selected from argon; the ball-to-material ratio of the fourth ball milling process is 10-15:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

[0030] In this invention, in step S5, the sintering process is rapid hot pressing sintering; the sintering pressure is 80-100 MPa, the temperature is 950-980℃, and the holding time is 5-10 min.

[0031] In this invention, in S5, the heating rate of the sintering process is 80-100℃ / min, and the vacuum degree of the sintering environment is ≤0.34Pa.

[0032] The present invention also provides a grain-heterogeneous tungsten-copper composite material, which is prepared according to the preparation method of the grain-heterogeneous tungsten-copper composite material.

[0033] The present invention also provides the application of the aforementioned grain-heterogeneous tungsten-copper composite material in the preparation of high-temperature service components for the electrical industry.

[0034] The following embodiments are provided to better understand the present invention and are not limited to the described embodiments. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] In the following embodiments and comparative examples of the present invention, all ball milling processes are performed in a cemented carbide grinding jar and using cemented carbide grinding balls.

[0037] Example 1 This embodiment provides a method for preparing a grain-isomorphic tungsten-copper composite material, including the following steps: It provides 75.8g of tungsten powder (particle size 10-14μm), 32.57g of copper powder (particle size 0.5-2μm) and 0.2g of titanium carbide powder (particle size ≤100nm).

[0038] 0.2g of titanium carbide powder and 19.8g of tungsten powder were ball-milled at a high-energy ball-to-powder ratio of 20:1, a rotation speed of 560 r / min, and a time of 6 h to obtain W-TiC composite powder. The W-TiC composite powder and 8.57g of copper powder were ball-milled with 18mL of anhydrous ethanol under an argon atmosphere at a rotation speed of 560 r / min for 5 h. After drying, nanocrystalline composite powder was obtained.

[0039] 56g of tungsten powder and 24g of copper powder were ball-milled under an argon atmosphere with a ball-to-powder ratio of 5:1, a rotation speed of 300r / min, and a time of 3h to obtain coarse-grained composite powder.

[0040] Under an argon atmosphere, 25.5g of nanocrystalline composite powder and 4.5g of coarse-crystalline composite powder were mixed and ball-milled. The ball-to-powder ratio was set to 13:1, the rotation speed was 300r / min, and the time was 3h to obtain the mixed powder.

[0041] The mixed powder was sintered (rapid hot pressing sintering) with a sintering pressure of 100 MPa, a temperature of 950 °C, a holding time of 6 min, a heating rate of 80 °C / min, and a vacuum degree of ≤0.34 Pa in the sintering furnace to obtain a crystalline heterogeneous tungsten-copper composite material.

[0042] Example 2 This embodiment provides a method for preparing a grain-heterogeneous tungsten-copper composite material, which differs from Embodiment 1 in that: the mass of the nanocrystalline composite powder is modified to 22.5g and the mass of the coarse-grained composite powder is 7.5g, that is, "22.5g of nanocrystalline composite powder and 7.5g of coarse-grained composite powder are mixed and ball-milled under an argon atmosphere."

[0043] Example 3 This embodiment provides a method for preparing a grain-heterogeneous tungsten-copper composite material, which differs from Embodiment 1 in that: the mass of the nanocrystalline composite powder is 15g and the mass of the coarse-grained composite powder is 15g, that is, "under an argon atmosphere, 15g of nanocrystalline composite powder and 15g of coarse-grained composite powder are mixed and ball-milled".

[0044] Comparative Example 1 This comparative example provides a method for preparing a tungsten-copper composite material. The use of titanium carbide powder in Example 1 is omitted, and it is replaced with an equal amount of tungsten powder. This comparative example specifically includes the following steps: It provides 76g of tungsten powder (particle size 10-14μm) and 32.57g of copper powder (particle size 0.5-2μm).

[0045] 20g of tungsten powder was ball-milled at a ball-to-powder ratio of 20:1, a rotation speed of 560 r / min, and a time of 6 h to obtain nanocrystalline W powder. The nanocrystalline W powder and 8.57g of copper powder were ball-milled with 18mL of anhydrous ethanol under an argon atmosphere at a rotation speed of 560 r / min for 5 h. After drying, nanocrystalline composite powder was obtained.

[0046] 56g of tungsten powder and 24g of copper powder were ball-milled under an argon atmosphere with a ball-to-powder ratio of 5:1, a rotation speed of 300r / min, and a time of 3h to obtain coarse-grained composite powder.

[0047] Under an argon atmosphere, 20.4 g of nanocrystalline composite powder and 3.6 g of coarse-crystalline composite powder were mixed and ball-milled. The ball-to-powder ratio was set to 13:1, the rotation speed was 300 r / min, and the time was 3 h to obtain the mixed powder.

[0048] The mixed powder was sintered (rapid hot pressing sintering) with a sintering pressure of 100 MPa, a temperature of 950 °C, a holding time of 6 min, a heating rate of 80 °C / min, and a vacuum degree of ≤0.34 Pa in the sintering furnace to obtain tungsten-copper composite material.

[0049] Comparative Example 2 This comparative example provides a method for preparing a tungsten-copper composite material, comprising the following steps: It provides 19.8g of tungsten powder (particle size 10-14μm), 8.57g of copper powder (particle size 0.5-2μm) and 0.2g of titanium carbide powder (particle size ≤100nm).

[0050] 0.2g of titanium carbide powder and 19.8g of tungsten powder were ball-milled at a high-energy ball-to-powder ratio of 20:1, a rotation speed of 560 r / min, and a time of 6 h to obtain W-TiC composite powder. The W-TiC composite powder and 8.57g of copper powder were ball-milled with 18mL of anhydrous ethanol under an argon atmosphere at a rotation speed of 560 r / min for 5 h. After drying, nanocrystalline composite powder was obtained.

[0051] The nanocrystalline composite powder was sintered (rapid hot pressing sintering) with a sintering pressure of 100 MPa, a temperature of 950 °C, a holding time of 6 min, a heating rate of 80 °C / min, and a vacuum degree of ≤0.34 Pa in the sintering furnace to obtain tungsten-copper composite material.

[0052] Experimental Example 1 Small samples were cut from the composite materials prepared in Examples 1, 3, 1, and 2 using wire cutting. After grinding and polishing, the samples were ultrasonically cleaned with anhydrous ethanol and dried. Subsequently, the surface microstructure was observed using scanning electron microscopy (SEM). The microstructure of the heterogeneous tungsten-copper composite material in Example 1 is shown in the image. Figure 1 As shown; Microscopic morphology diagram of the grain-isomorphic tungsten-copper composite material in Example 3, as shown. Figure 2 As shown; the microstructure of the tungsten-copper composite material in Comparative Example 1 is shown in the figure. Figure 3 As shown; the microstructure of the tungsten-copper composite material in Comparative Example 2 is shown in the figure. Figure 4 As shown. From Figure 1-4 As can be seen, the composite materials of Examples 1, 3, and Comparative Example 1 all exhibit clear heterogeneous structural characteristics, namely, they are composed of small nanocrystalline regions and relatively large coarse-grained regions. In contrast, Comparative Example 2 exhibits a more uniform structure and does not possess the heterogeneous characteristics of "nanocrystalline-coarse-grained".

[0053] To further reveal the fine structure of the nanocrystalline region, high-resolution observation of the small-scale W phase region in the composite material of Example 1 was performed using transmission electron microscopy (TEM). The TEM characterization images of the small-scale W phase region in the composite material of Example 1 were obtained, as shown below. Figure 5 As shown. From Figure 5 It can be seen that the W phase consists of a large number of grains with a size at the nanoscale.

[0054] To investigate the behavior of added TiC during the sintering process, high-resolution TEM and selected area electron diffraction analysis were performed on the grain boundaries of the nanocrystalline region in the composite material of Example 1. The resulting diagram shows the presence state of Ti at the grain boundaries of the nanocrystalline region in the composite material of Example 1. Figure 6 As shown; Figure 6 In the image, 'a' represents the TEM characterization of the TiO2 / W interface. Figure 6 In the diagram, b is the Fast Fourier Transform analysis of TiO2 in a. Figure 6 In the diagram, 'c' represents the Fast Fourier Transform analysis of the W matrix in 'a'. From... Figure 6 It can be seen that the added TiC reacted with oxygen in the system during the sintering process, and was converted into TiO2 in situ, mainly distributed at the grain boundaries of W nanocrystals.

[0055] Experiment Example 2 Small cylindrical compression specimens with a diameter of 3 mm and a height of 6 mm were cut from the composite materials prepared in Examples 1-3 and Comparative Examples 1-2. These specimens were then subjected to compression testing using a universal testing machine at a strain rate of 5 × 10⁻⁶ mm. -4 s -1 The room temperature compressive properties of the composite materials were tested under the specified conditions, and the room temperature compressive stress-strain curves of different composite materials were obtained, as shown in the figure. Figure 7 As shown. From Figure 7 The results show that the room temperature compressive yield strength of the composite material in Example 1 is approximately 1390 MPa, and the plastic strain is approximately 5%; the room temperature compressive yield strength of the composite material in Example 2 is approximately 1227 MPa, and the plastic strain is approximately 7%; the room temperature compressive yield strength of the composite material in Example 3 is approximately 1060 MPa, and the plastic strain is approximately 12%; the room temperature compressive yield strength of the composite material in Comparative Example 1 is approximately 1227 MPa, and the plastic strain is approximately 5%, which is lower than that of Example 1 with TiC added to the nanocrystalline W phase; the room temperature compressive strength of the composite material in Comparative Example 2 is approximately 1423 MPa, but no significant plastic deformation occurred. These results indicate that the materials of the present invention, while maintaining a high yield strength, exhibit superior plastic deformation capacity compared to the comparative materials, achieving a good synergy between strength and plasticity.

[0056] Experimental Example 3 The conductivity of the grain-heterogeneous tungsten-copper composite materials in Examples 1-3 was tested using a Sigma2008B eddy current conductivity meter from Xiamen Tianyan. The conductivity of the composite material in Example 1 was approximately 42% IACS; the conductivity of the composite material in Example 2 was approximately 43% IACS; and the conductivity of the composite material in Example 3 was approximately 45% IACS.

[0057] Experiment Example 4 The Vickers hardness of the composite materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 was tested at room temperature, 300°C, and 600°C. The hardness variation curves of the different composite materials with temperature were obtained, as shown in the figure. Figure 8 As shown. From Figure 8 The results show that the composite material of Example 1 has a room temperature hardness of 382 HV and a hardness of 150 HV at 600℃, with a room temperature hardness retention rate of 39.3%; the hardness retention rate in the temperature range from 300℃ to 600℃ is 75.0%, demonstrating excellent resistance to high-temperature softening. The composite material of Comparative Example 1 has a room temperature hardness of 371 HV and a hardness of 133 HV at 600℃, with a room temperature hardness retention rate of 35.8% (67.0% in the temperature range from 300℃ to 600℃). The composite material of Comparative Example 2 has a room temperature hardness of 418 HV and a hardness retention rate of 40.0% at 600℃ (72.0% in the temperature range from 300℃ to 600℃). The comparative results indicate that the material of Example 1 of this invention has a hardness retention rate as high as 75.0% in the temperature range of 300℃ to 600℃, which is at the same excellent level as Comparative Example 2 (72.0%), which is entirely composed of nanocrystals. This demonstrates that the heterostructure constructed in this invention successfully retains the inherent high thermal stability advantage of the nanocrystalline phase while introducing a coarse-grained phase to improve plasticity. In contrast, the material of Comparative Example 1 without TiC showed a significantly lower high-temperature hardness retention rate (67.0%) compared to Example 1. This direct comparison confirms that the addition of trace amounts of TiC and its in-situ transformation into grain boundary TiO2 during sintering plays a decisive role in pinning grain boundaries and inhibiting microstructure coarsening at high temperatures, and is a core factor in significantly improving the material's resistance to high-temperature softening.

[0058] The Vickers hardness of the composite materials prepared in Examples 2 and 3 were tested at room temperature using the same method. The room temperature hardness of the composite material in Example 2 was 365 HV, and the hardness of the composite material in Example 3 was 330 HV.

[0059] Therefore, the present invention adopts the above-mentioned grain heterogeneous tungsten copper composite material, its preparation method and application, by designing and constructing a specific heterostructure composed of W phase nanocrystalline region and coarse-grained region, and introducing titanium carbide to transform it in situ into titanium dioxide distributed at the grain boundaries during sintering, thereby synergistically improving the strength, plasticity, conductivity and high temperature stability of the material.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a tungsten-copper composite material with heterogeneous grains, characterized in that, Includes the following steps: S1. Provides tungsten powder, copper powder and titanium carbide powder; S2. Titanium carbide powder and tungsten powder from the first part are subjected to a first ball milling process to obtain W-TiC composite powder; W-TiC composite powder and copper powder from the first part are subjected to a second ball milling process to obtain nanocrystalline composite powder; S3. The remaining tungsten powder and the remaining copper powder are subjected to a third ball milling process to obtain coarse-grained composite powder; S4. The nanocrystalline composite powder and the coarse-crystalline composite powder are subjected to a fourth ball milling process to obtain a mixed powder; S5. The mixed powder is sintered to obtain a crystalline heterogeneous tungsten-copper composite material.

2. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S1, the mass ratio of tungsten powder, copper powder and titanium carbide powder is 70-80:25-40:0.05-2.

3. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S2, the ball-to-material ratio for the first ball milling process is 15-20:1, the rotation speed is 500-600 r / min, and the time is 6-10 h.

4. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S2, the second ball milling process is carried out under a protective atmosphere. The ball-to-material ratio for the second ball milling process is 10-20:1, the rotation speed is 500-600 r / min, and the time is 3-5 h.

5. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S3, the third ball milling process is carried out under a protective atmosphere. The ball-to-material ratio for the third ball milling process is 5-8:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

6. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S4, the fourth ball milling process is carried out under a protective atmosphere. The ball-to-material ratio for the fourth ball milling process is 10-15:1, the rotation speed is 280-320 r / min, and the time is 3-5 h.

7. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1, characterized in that, In S5, the sintering pressure is 80-100MPa, the temperature is 950-980℃, and the holding time is 5-10min.

8. The method for preparing the grain-heterogeneous tungsten-copper composite material according to claim 1 or 7, characterized in that, In S5, the heating rate of the sintering process is 80-100℃ / min, and the vacuum degree of the sintering environment is ≤0.34Pa.

9. A tungsten-copper composite material with heterogeneous grain structure, characterized in that, The composite material with grain heterogeneous tungsten copper is prepared according to any one of claims 1-8.

10. The application of the grain-heterogeneous tungsten-copper composite material according to claim 9 in the preparation of high-temperature service components for the electrical industry.

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