A method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper

Abstract

The invention discloses a method for preparing a high-strength, high-conductivity, non-uniform grain structure alumina dispersion strengthened copper, the method comprising: 1. electrolytic copper powder and ethanol deformation and flake treatment; 2. high-temperature oxidation treatment; 3. low-speed dry grinding and crushing treatment; 4. large ball-to-material ratio ball milling activation and refinement; 5. small ball-to-material ratio ball milling activation; 6. heat treatment; 7. reduction treatment; 8. room temperature pre-pressing, crushing and exhausting followed by discharge plasma sintering. The invention constructs a multi-scale distributed powder through two-stage ball milling mixing of large ball-to-material ratio ball milling activation and refinement and small ball-to-material ratio ball milling activation, and forms non-uniform grain structure alumina dispersion strengthened copper after sintering, utilizes copper nanocrystals and ultrafine crystals and alumina nanoparticles distribution enriched area to strengthen the material, utilizes copper large grains and alumina nanoparticles distribution deficient area to reduce the electron scattering effect, so that the alumina dispersion strengthened copper has high strength performance while retaining excellent conductivity, and has a simple process and is easy to control.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper. Background Art

[0002] Alumina dispersion strengthened copper has excellent conductivity, high strength and superior high temperature resistance. It has great development potential and application prospects in high-tech fields such as electronic information technology, new energy vehicles, high-speed rail transit and aerospace.

[0003] At present, the most commonly used method for preparing alumina dispersion strengthened copper is the internal oxidation method. One of the most important processes of the internal oxidation method is that copper-aluminum alloy powder and oxidant generate dispersed alumina particles at high temperature. The uniformly distributed alumina particles have a very strong scattering effect on electrons, resulting in a sharp decline in conductivity. At the same time, the mass fraction of alumina depends on the solid solubility of aluminum in copper, so it is difficult to obtain alumina particles with a high mass fraction. In addition, the internal oxidation method is complex, each step of the process requires precise control, the production cycle is long, the product performance is unstable, and the product price is expensive. The ball milling method can arbitrarily mix powders of different mass fractions and different particle sizes, has high flexibility and design, can regulate the grain size and reinforcement distribution, achieve the purpose of reducing the electron scattering effect, and avoid the problem of solid solubility limitation. At the same time, as the alumina content of alumina dispersion strengthened copper increases, the conductivity of the composite material will drop sharply. The great challenge faced by researchers is how to make the high mass fraction alumina dispersion strengthened copper have high strength while avoiding the reduction of conductivity as much as possible.

[0004] Therefore, the problem that technicians in this field urgently need to solve is to propose a method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper, so as to solve the technical problem that high-mass fraction alumina dispersion strengthened copper in the prior art cannot simultaneously obtain high strength and high conductivity. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing alumina dispersion-strengthened copper with a high-strength and high-conductivity non-uniform grain structure in view of the deficiencies of the above-mentioned prior art. The method constructs a multi-scale distributed powder by two-stage ball milling mixing of ball milling activation and refinement with a large ball-to-material ratio and ball milling activation with a small ball-to-material ratio, and forms alumina dispersion-strengthened copper with a non-uniform grain structure after sintering, which reduces the electron scattering effect while strengthening the material, so that the alumina dispersion-strengthened copper has high strength performance while retaining excellent conductivity, solving the problem in the prior art that high-mass fraction alumina dispersion-strengthened copper cannot simultaneously obtain high strength and high conductivity.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper, characterized in that the method comprises the following steps:

[0007] Step 1: subjecting electrolytic copper powder and process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flake copper powder A;

[0008] Step 2: subjecting the flaky copper powder A obtained in step 1 to high-temperature oxidation treatment in an oxygen atmosphere to form an oxide film on the surface of the flaky copper powder A;

[0009] Step 3, subjecting the flaky copper powder A after high-temperature oxidation in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0010] Step 4: taking part of the powder B obtained in step 3, aluminum powder and ethanol, and subjecting them to high-ball-to-material ratio ball milling activation and refinement, and then vacuum drying to obtain a mixed powder C; the high-ball-to-material ratio ball milling activation and refinement ball ratio is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 24h to 36h;

[0011] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to ball milling activation with a small ball to material ratio, and then vacuum dried to obtain powder D; the ball to material ratio of the small ball to material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 24h to 36h;

[0012] Step 6: heat-treating the powder D obtained in step 5 to obtain powder E; the heat treatment temperature is 700° C. and the holding time is 1 h;

[0013] Step 7: subjecting the powder E obtained in step 6 to reduction treatment in a reducing atmosphere to obtain powder F; the reduction treatment temperature is 400° C., and the reduction time is 3 h;

[0014] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then spark plasma sintered to obtain alumina dispersion strengthened copper; the parameters of the spark plasma sintering are: 750°C to 950°C, holding time 10min to 30min, and sintering pressure 40MPa.

[0015] The present invention performs deformation and flake treatment on electrolytic copper powder, such as ball milling to obtain flaky copper powder A, and performs high-temperature oxidation to generate an oxide film on the surface of the electrolytic copper powder. The powder B is further crushed and refined by low-speed dry grinding and crushing treatment, and then two-stage ball milling and mixing are performed, that is, firstly, part of the powder B is subjected to first-stage large ball-to-material ratio ball milling activation and refinement with aluminum powder and ethanol, and high-mass fraction aluminum powder is introduced by external addition method, and the sizes of each powder are greatly refined to obtain a mixed powder C containing high-mass fraction nano-scale aluminum powder, and then the remaining powder B is subjected to second-stage small ball-to-material ratio ball milling activation with the mixed powder C and ethanol. Since the mixed powder C is obtained by ball milling activation and refinement with a large ball-to-material ratio, the scale of the first-stage ball milling powder B contained in the mixed powder C is different from the scale of the second-stage ball milling remaining powder B, and the nano-aluminum powder is unevenly distributed, and the nano-aluminum powder is mainly concentrated at the first-stage ball milling powder B. Since the copper powder is not completely oxidized, the remaining copper powder has a certain plasticity, and the second-stage ball milling does not make it uniformly refined, thereby obtaining a powder with multi-scale distribution. D, after heat treatment, the copper oxide in the oxide film reacts with the nano-aluminum powder to form nano-aluminum oxide, and a powder E containing nano-aluminum oxide is obtained. After reduction treatment, the copper oxide is further reduced to obtain a powder F composed of copper and nano-aluminum oxide. The powder F is pre-pressed, crushed and exhausted at room temperature and then sintered. Due to the uneven distribution of nano-aluminum oxide nanoparticles, the growth of copper matrix grains is hindered, and the multi-scale distribution of copper particles is retained to form a non-uniform grain structure alumina dispersion strengthened copper, that is, alumina nanoparticle distribution enrichment zone and depletion zone are formed in the copper matrix, resulting in a multi-scale distribution of the grain size of the copper matrix. The alumina nanoparticle distribution enrichment zone and the copper nanocrystals and ultrafine crystals are used to play a strengthening role, thereby improving the strength of the alumina dispersion strengthened copper. At the same time, the large copper grains and the alumina nanoparticle distribution depletion zone increase the electron transmission channel, reduce the electron scattering effect, and avoid a sharp decline in conductivity, so that the alumina dispersion strengthened copper has high strength performance while retaining excellent conductivity.

[0016] The above-mentioned method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper is characterized in that the aerobic atmosphere environment in step 2 is air, oxygen, or a mixture of oxygen and inert gas.

[0017] The above-mentioned method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper is characterized in that the atmosphere conditions used for the heat treatment in step six are vacuum or inert gas.

[0018] The above-mentioned method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper is characterized in that the reducing atmosphere in step seven is hydrogen or a mixture of hydrogen and inert gas.

[0019] The above-mentioned method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper is characterized in that the mass content of aluminum in the powder F in step eight is 0.18% to 0.6%.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention constructs a multi-scale distributed powder through two-stage ball milling mixing of ball milling activation and refinement with a large ball-to-material ratio and ball milling activation with a small ball-to-material ratio, and forms a non-uniform grain structure alumina dispersion strengthened copper after sintering. While strengthening the material by using copper nanocrystals and ultrafine crystals and alumina nanoparticles distribution enriched areas, the electron scattering effect is reduced by using copper large grains and alumina nanoparticles distribution deficient areas, so that the alumina dispersion strengthened copper has high strength performance while retaining excellent electrical conductivity.

[0022] 2. The present invention introduces aluminum powder by an external addition method and generates aluminum oxide nanoparticles through heat treatment, without considering the solid solubility of aluminum in copper, greatly increasing the amount of aluminum powder added, further enhancing the dispersion strengthening effect of aluminum oxide nanoparticles, thereby improving the strength of aluminum oxide dispersion strengthened copper.

[0023] 3. The present invention pre-deforms the electrolytic copper powder to obtain flaky copper powder A, which increases the width and length of the copper powder, expands the gaps between the powders, ensures that the oxygen atmosphere flows smoothly between the powders during the high-temperature oxidation process, and improves the uniformity of the powder oxidation.

[0024] 4. The present invention introduces high mass fraction impurities during the ball milling activation and refinement process with a large ball to material ratio, but the total amount of impurities introduced is small due to the small overall powder mass. Meanwhile, the small ball to material ratio ball milling activation process also introduces fewer impurities, but at this time the overall powder mass is large and the total impurity content is controllable, thereby avoiding the introduction of excessive impurities during the preparation process that affects the conductive properties of alumina dispersion-strengthened copper.

[0025] 5. The preparation process of the present invention is simple, easy to control, and low in cost, and the product alumina dispersion strengthened copper has good comprehensive properties.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a SEM image of the electrolytic copper powder after deformation and flake processing in Example 1 of the present invention.

[0028] Figure 2 This is a SEM image of the flaky copper powder after high temperature oxidation treatment in Example 1 of the present invention.

[0029] Figure 3This is a metallographic diagram of the alumina dispersion strengthened copper prepared in Example 4 of the present invention after rolling treatment.

[0030] Figure 4a This is the full EBSD image of copper grains after rolling treatment of alumina dispersion strengthened copper prepared in Example 4 of the present invention.

[0031] Figure 4b for Figure 4a Decomposition diagram of medium grain size 0~0.5μm.

[0032] Figure 4c for Figure 4a Decomposition diagram of medium grain size 0.5μm~1μm.

[0033] Figure 4d for Figure 4a Decomposition diagram of medium grain size 1μm~1.5μm.

[0034] Figure 4e for Figure 4a Decomposition diagram of medium grain size 1.5μm~4μm. DETAILED DESCRIPTION

[0035] Example 1

[0036] This embodiment includes the following steps:

[0037] Step 1: subjecting the electrolytic copper powder and the process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flaky copper powder A; the deformation and flake treatment is ball milling, and the ball milling speed is 500 rpm, and the ball milling time is 6 hours;

[0038] Step 2: subjecting the flaky copper powder obtained in step 1 to high temperature oxidation treatment at 250° C. for 6 hours in an air environment to form an oxide film on the surface of the copper powder;

[0039] Step 3, subjecting the flaky copper powder oxidized at high temperature in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0040] Step 4: Take part of the powder B obtained in step 3, aluminum powder and ethanol, and perform ball milling activation and refinement with a large ball-to-material ratio, and then vacuum dry to obtain a mixed powder C with an aluminum mass fraction of 1%; the ball-to-material ratio of the large ball-to-material ratio ball milling activation and refinement is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 24 hours;

[0041] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to small ball-to-material ratio ball milling activation, and then vacuum dried to obtain powder D; the ball-to-material ratio of the small ball-to-material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 24 hours;

[0042] Step 6: heat-treat the powder D obtained in step 5 under vacuum at a temperature of 700° C. for 1 h to obtain powder E;

[0043] Step 7: The powder E obtained in step 6 is subjected to reduction treatment in hydrogen at a temperature of 400° C. for 3 h to obtain powder F;

[0044] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then subjected to spark plasma sintering. The parameters of the spark plasma sintering are: 850° C., holding time 10 min, sintering pressure 40 MPa, to obtain alumina dispersion-strengthened copper with an aluminum mass fraction of 0.18%.

[0045] Figure 1 is the SEM image of the electrolytic copper powder after deformation and flake processing in this embodiment. Figure 1 It can be seen that the electrolytic copper powder after deformation and flaking treatment is in a flake shape, and the horizontal size is significantly increased, which effectively increases the gaps between the powders.

[0046] Figure 2 is the SEM image of the flaky copper powder after high temperature oxidation treatment in this embodiment. Figure 2 It can be seen that the surface of the flaky copper powder is uniformly oxidized after high-temperature oxidation treatment.

[0047] Example 2

[0048] This embodiment includes the following steps:

[0049] Step 1: subjecting the electrolytic copper powder and the process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flaky copper powder A; the deformation and flake treatment is ball milling, and the ball milling speed is 500 rpm, and the ball milling time is 6 hours;

[0050] Step 2: subjecting the flaky copper powder obtained in step 1 to high temperature oxidation treatment at 250° C. for 6 hours in an oxygen environment to form an oxide film on the surface of the copper powder;

[0051] Step 3, subjecting the flaky copper powder oxidized at high temperature in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0052] Step 4: Take part of the powder B obtained in step 3, aluminum powder and ethanol, and perform ball milling activation and refinement with a large ball-to-material ratio, and then vacuum dry to obtain a mixed powder C with an aluminum mass fraction of 2.3%; the ball-to-material ratio of the large ball-to-material ratio ball milling activation and refinement is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 24 hours;

[0053] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to small ball-to-material ratio ball milling activation, and then vacuum dried to obtain powder D; the ball-to-material ratio of the small ball-to-material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 24 hours;

[0054] Step 6: heat-treating the powder D obtained in step 5 under argon at a temperature of 700° C. for 1 h to obtain powder E;

[0055] Step 7: The powder E obtained in step 6 is subjected to reduction treatment in a mixture of hydrogen and argon at a temperature of 400° C. for 3 h to obtain powder F;

[0056] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then subjected to spark plasma sintering. The parameters of the spark plasma sintering are: 850° C., holding time 10 min, sintering pressure 40 MPa, to obtain alumina dispersion-strengthened copper with an aluminum mass fraction of 0.35%.

[0057] The alumina dispersion strengthened copper prepared in Example 2 was rolled, and then the mechanical properties and electrical conductivity were tested, and compared with the alumina dispersion strengthened copper in the prior art. The results are shown in Table 1.

[0058] Table 1

[0059]

[0060]

[0061] Document 1: Song K,

[0062] Document 2: Li C, Xie Y, Zhou D, et al. A novel way for fabricating ultrafinegrained Cu-4.5vol%Al2O3 composite with high strength and electricalconductivity. Materials Characterization, 2019,155:109775.

[0063] Document 3: Lee J, Kim YC, Lee S, et al. Correlation of the microstructure and mechanical properties of oxide-dispersion-strengthened coppers fabricated by internal oxidation. Metallurgical and Materials Transactions A, 2004, 35(2): 493-502.

[0064] It can be seen from Table 1 that the alumina dispersion strengthened copper prepared in this example exhibits high strength and high conductivity, indicating that the method of the present invention constructs a non-uniform grain structure, which improves the strength of the alumina dispersion strengthened copper while avoiding a significant decrease in its conductivity.

[0065] Example 3

[0066] This embodiment includes the following steps:

[0067] Step 1: subjecting the electrolytic copper powder and the process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flaky copper powder A; the deformation and flake treatment is ball milling, and the ball milling speed is 500 rpm, and the ball milling time is 6 hours;

[0068] Step 2: subjecting the flaky copper powder obtained in step 1 to high temperature oxidation treatment at 250° C. for 6 hours in an air environment to form an oxide film on the surface of the copper powder;

[0069] Step 3, subjecting the flaky copper powder oxidized at high temperature in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0070] Step 4: Take part of the powder B obtained in step 3, aluminum powder and ethanol, and perform ball milling activation and refinement with a large ball-to-material ratio, and then vacuum dry to obtain a mixed powder C with an aluminum mass fraction of 2.5%; the ball-to-material ratio of the large ball-to-material ratio ball milling activation and refinement is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 36 hours;

[0071] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to small ball-to-material ratio ball milling activation, and then vacuum dried to obtain powder D; the ball-to-material ratio of the small ball-to-material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 36 hours;

[0072] Step 6: heat-treat the powder D obtained in step 5 under vacuum at a temperature of 700° C. for 1 h to obtain powder E;

[0073] Step 7: The powder E obtained in step 6 is subjected to reduction treatment in hydrogen at a temperature of 400° C. for 3 h to obtain powder F;

[0074] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then subjected to spark plasma sintering. The parameters of the spark plasma sintering are: 750° C., holding time 10 min, sintering pressure 40 MPa, to obtain alumina dispersion-strengthened copper with an aluminum mass fraction of 0.6%.

[0075] Example 4

[0076] This embodiment includes the following steps:

[0077] Step 1: subjecting the electrolytic copper powder and the process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flaky copper powder A; the deformation and flake treatment is ball milling, and the ball milling speed is 500 rpm, and the ball milling time is 6 hours;

[0078] Step 2: subjecting the flaky copper powder obtained in step 1 to high-temperature oxidation treatment at 250° C. for 6 hours in an air environment to form an oxide film on the surface of the copper powder; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 minutes;

[0079] Step 3, subjecting the flaky copper powder oxidized at high temperature in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0080] Step 4: Take part of the powder B obtained in step 3, aluminum powder and ethanol, and perform ball milling activation and refinement with a large ball-to-material ratio, and then vacuum dry to obtain a mixed powder C with an aluminum mass fraction of 2.5%; the ball-to-material ratio of the large ball-to-material ratio ball milling activation and refinement is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 36 hours;

[0081] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to small ball-to-material ratio ball milling activation, and then vacuum dried to obtain powder D; the ball-to-material ratio of the small ball-to-material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 36 hours;

[0082] Step 6: heat-treat the powder D obtained in step 5 under vacuum at a temperature of 700° C. for 1 h to obtain powder E;

[0083] Step 7: The powder E obtained in step 6 is subjected to reduction treatment in hydrogen at a temperature of 400° C. for 3 h to obtain powder F;

[0084] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then subjected to spark plasma sintering. The parameters of the spark plasma sintering are: 950° C., holding time 30 min, sintering pressure 40 MPa, to obtain alumina dispersion-strengthened copper with an aluminum mass fraction of 0.6%.

[0085] Figure 3 This is the metallographic image of the aluminum oxide dispersion strengthened copper prepared in this embodiment after rolling treatment. Figure 3 It can be seen that there are areas of enrichment and depletion of large-grained alumina nanoparticles inside the alumina dispersion-strengthened copper.

[0086] Figure 4a This is the full EBSD image of copper grains after rolling treatment of alumina dispersion strengthened copper prepared in Example 4 of the present invention. Figure 4b to Figure 4e for Figure 4a EBSD decomposition diagram of copper grains of different grain sizes, from Figure 4a to Figure 4e It can be seen that the internal grain structure of the alumina dispersion-strengthened copper is composed of nanocrystalline, ultrafine-crystalline, and coarse-crystalline copper matrix grains, forming a multi-scale non-uniform grain structure.

[0087] Example 5

[0088] This embodiment includes the following steps:

[0089] Step 1: subjecting the electrolytic copper powder and the process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flaky copper powder A; the deformation and flake treatment is ball milling, and the ball milling speed is 500 rpm, and the ball milling time is 6 hours;

[0090] Step 2: subjecting the flaky copper powder obtained in step 1 to high temperature oxidation treatment at 250° C. for 6 hours in an air environment to form an oxide film on the surface of the copper powder;

[0091] Step 3, subjecting the flaky copper powder oxidized at high temperature in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min;

[0092] Step 4: Take part of the powder B obtained in step 3, aluminum powder and ethanol, and perform ball milling activation and refinement with a large ball-to-material ratio, and then vacuum dry to obtain a mixed powder C with an aluminum mass fraction of 2.5%; the ball-to-material ratio of the large ball-to-material ratio ball milling activation and refinement is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 30 hours;

[0093] Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to small ball-to-material ratio ball milling activation, and then vacuum dried to obtain powder D; the ball-to-material ratio of the small ball-to-material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 30 hours;

[0094] Step 6: heat-treat the powder D obtained in step 5 under vacuum at a temperature of 700° C. for 1 h to obtain powder E;

[0095] Step 7: The powder E obtained in step 6 is subjected to reduction treatment in hydrogen at a temperature of 400° C. for 3 h to obtain powder F;

[0096] Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then subjected to spark plasma sintering. The parameters of the spark plasma sintering are: 900° C., holding time 20 min, sintering pressure 40 MPa, to obtain alumina dispersion-strengthened copper with an aluminum mass fraction of 0.6%.

[0097] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper, characterized in that: The method comprises the following steps: Step 1: subjecting electrolytic copper powder and process control agent ethanol to deformation and flake treatment, and then vacuum drying to obtain flake copper powder A; Step 2: subjecting the flaky copper powder A obtained in step 1 to high-temperature oxidation treatment in an oxygen atmosphere to form an oxide film on the surface of the flaky copper powder A; Step 3, subjecting the flaky copper powder A after high-temperature oxidation in step 2 to low-speed dry grinding and crushing to obtain powder B; the ball milling speed of the low-speed dry grinding and crushing treatment is 200 rpm, and the ball milling time is 30 min; Step 4: taking part of the powder B obtained in step 3, aluminum powder and ethanol, and subjecting them to high-ball-to-material ratio ball milling activation and refinement, and then vacuum drying to obtain a mixed powder C; the high-ball-to-material ratio ball milling activation and refinement ball ratio is 20:1, the ball milling speed is 500 rpm, and the ball milling time is 24h to 36h; Step 5: The mixed powder C obtained in step 4, the powder B obtained in the remaining step 3, and ethanol are subjected to ball milling activation with a small ball to material ratio, and then vacuum dried to obtain powder D; the ball to material ratio of the small ball to material ratio ball milling activation is 6:1, the ball milling speed is 500 rpm, and the ball milling time is 24h to 36h; Step 6: heat-treating the powder D obtained in step 5 to obtain powder E; the heat treatment temperature is 700° C. and the holding time is 1 h; Step 7: subjecting the powder E obtained in step 6 to reduction treatment in a reducing atmosphere to obtain powder F; the reduction treatment temperature is 400° C., and the reduction time is 3 h; Step 8: The powder F obtained in step 7 is pre-pressed, crushed and exhausted at room temperature, and then spark plasma sintered to obtain alumina dispersion strengthened copper; the parameters of the spark plasma sintering are: 750°C to 950°C, holding time 10min to 30min, and sintering pressure 40MPa.

2. The method for preparing a high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper according to claim 1, characterized in that: The aerobic atmosphere environment in step 2 is air, oxygen or a mixture of oxygen and inert gas.

3. The method for preparing a high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper according to claim 1, characterized in that: The heat treatment in step six is ​​performed under vacuum or inert gas atmosphere.

4. The method for preparing a high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper according to claim 1, characterized in that: The reducing atmosphere in step seven is hydrogen or a mixture of hydrogen and an inert gas.

5. The method for preparing high-strength and high-conductivity non-uniform grain structure alumina dispersion strengthened copper according to claim 1, characterized in that: The mass content of aluminum in the powder F in step eight is 0.18% to 0.6%.

Images