Preparation method of high-strength aluminum-based composite material

Abstract

The invention discloses a preparation method of a high-strength aluminum-based composite material, and belongs to the technical field of metal-based composite materials. The method comprises the following steps: firstly, carrying out primary low-speed ball milling on aluminum powder, carbon nanotubes and aluminum-based intermediate alloy powder containing zirconium and scandium to obtain premixed powder; then, micron-sized SiC powder is added for secondary ball milling, and composite powder is obtained; carrying out hot pressing sintering to prepare a green body; and finally, the blank is subjected to temperature-controlled multi-pass hot rolling, and a finished product is obtained. According to the prepared composite material, the mechanical property, heat conduction and electric conductivity are synergistically improved, and the inherent problem that strength and plasticity of a traditional material are difficult to consider at the same time is remarkably solved. According to the adopted physical-thermal mechanical synergistic process, the method is relatively simple to operate and controllable in cost, and a new technical route is opened up for obtaining the aluminum-based composite material with more excellent performance and wider application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal matrix composites, in particular to a preparation method of high-strength aluminum matrix composite. BACKGROUND

[0002] Aluminum matrix composites have broad application prospects in the fields of aerospace, automobile manufacturing, and electronic packaging due to their high specific strength, high specific modulus, good thermal and electrical conductivity, etc. Among them, aluminum matrix composites with ceramic particles (such as SiC, Al2O3) and carbon materials (such as graphene, carbon nanotubes) as reinforcing phases are the research focus.

[0003] However, the further development of aluminum matrix composites currently faces three core technical bottlenecks: First, when introducing hard and brittle reinforcing phases (especially nanometer reinforcing phases) with high strength and high modulus, the plasticity and toughness of the material are often severely damaged, leading to an increased risk of brittle fracture of the material during service. Second, reinforcing phases, especially carbon materials (such as graphene, carbon nanotubes) of nanometer size, are prone to agglomeration due to their large specific surface area and high surface energy, making it difficult to achieve uniform dispersion in the aluminum matrix, forming stress concentration points and becoming crack sources, thereby deteriorating the material performance. In order to improve the dispersibility and interface bonding, existing technologies often use complex reinforcing phase surface modification methods (for example, the method disclosed in CN116144964B for generating a yttrium and tantalum boride compound on the surface of graphene to improve dispersibility), but these methods have long process flow, high cost, and poor controllability, and in addition, the intrinsic excellent performance of the reinforcing phase may be damaged during the modification process.

[0004] Therefore, there is an urgent need in the field to develop a new preparation method for aluminum matrix composites to address the shortcomings of existing technologies. SUMMARY

[0005] In view of the above, it is necessary to provide a preparation method of high-strength aluminum matrix composite, which is relatively simple in operation, controllable in cost, and can obtain aluminum matrix composite with high strength and high toughness.

[0006] To achieve the above purpose, the technical solution adopted by the present application is:

[0007] A preparation method of high-strength aluminum matrix composite, comprising the following steps:

[0008] (1) mixing aluminum powder, carbon nanotubes, and aluminum-based intermediate alloy powder by primary ball milling, with a ball milling speed of 100-200 rpm and a ball milling time of 1-3 hours to obtain a pre-mixed powder; using the plastic deformation of aluminum powder to preliminarily "wrap" the soft carbon nanotubes on the surface of the aluminum powder, avoiding direct collision and entanglement of the carbon nanotubes with hard particles, and achieving pre-dispersion of the carbon nanotubes;

[0009] (2) adding SiC powder into the premixed powder, and then performing secondary ball milling mixing at a ball milling speed of 250-400 rpm for 4-8 hours to obtain a composite powder; the pre-dispersed carbon nanotubes and the subsequently added micron SiC particles are embedded into the aluminum powder matrix under the action of ball milling to form a micron-nanometer multi-scale mixed uniform composite powder;

[0010] (3) loading the composite powder into a mold, and performing hot-press sintering under vacuum or inert gas protection at a sintering temperature of 500-580℃, a pressure of 30-50 MPa, and a holding time of 0.5-2 hours to obtain a dense composite material blank;

[0011] (4) performing multi-pass hot rolling on the composite material blank to obtain the high-strength aluminum-based composite material.

[0012] In the present application, further, in steps (1)-(2), the components are as follows in terms of mass percentage: SiC powder 5-15%, carbon nanotubes 0.5-2%; aluminum-based intermediate alloy powder is an aluminum-based intermediate alloy powder containing zirconium and scandium, which provides 0.1-0.5% of Zr element and 0.05-0.2% of Sc element in terms of the total mass of the composite material, and the balance is aluminum powder. The addition of trace amounts of Zr and Sc can in-situ form nanoscale intermetallic compounds such as Al3Zr and Al3Sc during sintering and hot rolling, which form a multi-level and multi-scale synergistic strengthening system with the external reinforcing phase (SiC, CNTs), effectively pin the grain boundaries and dislocations, strengthen the matrix, inhibit recrystallization and grain growth, and help to maintain toughness.

[0013] In the present application, further, the particle size of the SiC powder is 1-10 μm, and the tube diameter of the carbon nanotubes is 10-30 nm and the length is 1-10 μm.

[0014] In the present application, further, in steps (1)-(2), the primary ball milling and the secondary ball milling are both performed under argon protection (purity ≥ 99.999%), and the ball-to-material ratio is 5-10:1.

[0015] In the present application, further, it is characterized in that the heating rate of the hot-press sintering in step (3) is 5-15℃ / min.

[0016] In the present application, further, the multi-pass hot rolling in step (4) refers to that the composite material blank is subjected to multi-pass hot rolling at a temperature of 420-480℃, wherein the deformation amount of each pass is controlled to be between 10% and 15%, and the total cumulative deformation amount reaches 60%-80%; after the hot rolling is completed, the material is air-cooled to room temperature.

[0017] Further, in the present application, the temperature of the billet is not fluctuated more than ±20℃ by using on-line induction heating between passes in the multi-pass hot rolling.

[0018] The present application also provides a high-strength aluminum matrix composite prepared by the above method. In the composite, micron-sized SiC particles and nanoscale carbon nanotubes form a multi-scale reinforcing phase, and the matrix grains are equiaxed fine grains formed by dynamic recrystallization.

[0019] The present application has at least the following beneficial effects:

[0020] 1. The present application successfully synchronously improves the strength, hardness and plasticity of the aluminum matrix composite through the dispersion strategy of two-step ball milling, the synergistic strengthening of micro-alloying elements and the interface and structure optimization of "controlled temperature multi-pass hot rolling". The material prepared by the method not only has the characteristics of high strength, but also shows good plasticity matching, effectively alleviating the contradiction between strength and toughness in traditional composites.

[0021] 2. In addition, the present application discards the chemical modification method which may damage the sp2 lattice structure of carbon nanotubes, and realizes good dispersion and strong interface combination of carbon nanotubes while maximizing the retention of its high thermal conductivity and high electrical conductivity through the combination of pure physical and mechanical and thermal mechanical paths. The final obtained composite has excellent mechanical properties and outstanding physical properties, and can be further applied to the fields of heat management, electronic packaging and other fields which require both structural strength and functional characteristics, and has a wider application prospect.

[0022] 3. The process flow adopted by the present application is simple, avoids complex surface modification of reinforcing phase, long-time high-temperature treatment and other links, the main process parameters are easy to control, the production efficiency is relatively high, the energy consumption is relatively reduced, and the large-scale and low-cost preparation of high-performance aluminum matrix composite is realized. DETAILED DESCRIPTION

[0023] All features disclosed in this specification, and / or all steps of any methods or processes disclosed in this specification, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0024] Any feature disclosed in this specification, unless stated otherwise, may be replaced by any feature that is equivalent in terms of the functionality or results.

[0025] Example 1:

[0026] The present embodiment discloses a preparation method of a high-strength aluminum matrix composite, which comprises the following steps:

[0027] (1) The aluminum powder, carbon nanotubes and aluminum-based master alloy powder are mixed by primary ball milling (under the protection of argon (purity ≥ 99.999%) ), the ball milling speed is 200 rpm, the ball milling time is 3 hours, and the ball-to-material ratio is 10:1; a premixed powder is obtained; the above components are in percentage by mass: SiC powder 15%, carbon nanotubes 2%; the aluminum-based master alloy powder is an aluminum-based master alloy powder containing zirconium and scandium, which provides 0.5% of Zr element and 0.2% of Sc element in the total mass of the composite material, and the balance is aluminum powder. The particle size of the SiC powder is 10 μm, and the carbon nanotube has a tube diameter of 30 nm and a length of 10 μm.

[0028] (2) SiC powder is added to the premixed powder, and then secondary ball milling (under the protection of argon (purity ≥ 99.999%) ) is performed for mixing, the ball milling speed is 400 rpm, the ball milling time is 8 hours, the ball-to-material ratio is 10:1, and a composite powder is obtained;

[0029] (3) The composite powder is loaded into a mold, and hot-press sintering is continued under the protection of argon gas, the temperature is raised to a sintering temperature of 580℃ at a rate of 15℃ / min, the pressure is 50 MPa, and the holding time is 2 hours, to obtain a dense composite material blank;

[0030] (4) The composite material blank is subjected to multi-pass hot rolling at a temperature of 480℃, wherein the deformation amount of each pass is controlled between 15%, and the total cumulative deformation amount reaches 80%; after hot rolling, the material is air-cooled to room temperature. The high-strength aluminum-based composite material is obtained. The pass-to-pass temperature of the multi-pass hot rolling is compensated by online induction heating, so that the blank temperature fluctuation range is not more than ±20℃.

[0031] Example 2:

[0032] The embodiment discloses a preparation method of a high-strength aluminum-based composite material, which comprises the following steps:

[0033] (1) The aluminum powder, carbon nanotubes and aluminum-based master alloy powder are mixed by primary ball milling (under the protection of argon (purity ≥ 99.999%) ), the ball milling speed is 200 rpm, the ball milling time is 3 hours, and the ball-to-material ratio is 10:1; a premixed powder is obtained; the above components are in percentage by mass: SiC powder 15%, carbon nanotubes 2%; the aluminum-based master alloy powder is an aluminum-based master alloy powder containing zirconium and scandium, which provides 0.5% of Zr element and 0.2% of Sc element in the total mass of the composite material, and the balance is aluminum powder. The particle size of the SiC powder is 10 μm, and the carbon nanotube has a tube diameter of 30 nm and a length of 10 μm.

[0034] (2) SiC powder is added to the premixed powder, and then secondary ball milling (under the protection of argon (purity ≥ 99.999%) is performed for mixing, the ball milling speed is 320 rpm, the ball milling time is 6 hours, and the ball-to-material ratio is 7:1, to obtain a composite powder;

[0035] (3) The composite powder is loaded into a mold, and hot-press sintering is performed under the protection of argon gas, the temperature is raised to a sintering temperature of 540°C at a rate of 10°C / min, the pressure is 40 MPa, and the holding time is 1.2 hours, to obtain a dense composite material blank;

[0036] (4) The composite material blank is subjected to multi-pass hot rolling at a temperature of 460°C, wherein the deformation amount of each pass is controlled to be between 12%, and the total cumulative deformation amount reaches 70%; after hot rolling, the material is air-cooled to room temperature. The high-strength aluminum-based composite material is obtained. The pass-to-pass temperature of the multi-pass hot rolling is compensated by an online induction heating method, so that the blank temperature fluctuation range is not more than ± 20°C.

[0037] Example 3:

[0038] The embodiment discloses a preparation method of a high-strength aluminum-based composite material, which comprises the following steps:

[0039] (1) Al powder, carbon nanotubes and aluminum-based intermediate alloy powder are subjected to primary ball milling (under the protection of argon (purity ≥ 99.999%) for mixing, the ball milling speed is 100 rpm, the ball milling time is 1 hour, and the ball-to-material ratio is 5:1; a premixed powder is obtained; the above components are calculated according to the mass percentage: SiC powder 5%, carbon nanotubes 0.5%; the aluminum-based intermediate alloy powder is an aluminum-based intermediate alloy powder containing zirconium and scandium, which provides 0.1% of Zr element and 0.05% of Sc element in the total mass of the composite material, and the balance is aluminum powder. The particle size of the SiC powder is 1 μm, and the tube diameter of the carbon nanotubes is 10 nm and the length is 1 μm.

[0040] (2) SiC powder is added to the premixed powder, and then secondary ball milling (under the protection of argon (purity ≥ 99.999%) is performed for mixing, the ball milling speed is 250 rpm, the ball milling time is 4 hours, and the ball-to-material ratio is 5:1, to obtain a composite powder;

[0041] (3) The composite powder is loaded into a mold, and hot-press sintering is performed under the protection of argon gas, the temperature is raised to a sintering temperature of 540°C at a rate of 10°C / min, the pressure is 40 MPa, and the holding time is 1.2 hours, to obtain a dense composite material blank;

[0042] (4) the composite blank is subjected to multi-pass hot rolling at a temperature of 420°C, wherein the deformation amount of each pass is controlled to be between 10%, and the total cumulative deformation amount reaches 60%; after the hot rolling is completed, the material is air-cooled to room temperature. The high-strength aluminum-based composite material is obtained. The multi-pass hot rolling is supplemented by on-line induction heating, so that the temperature fluctuation range of the blank is not more than ±20°C.

[0043] Comparative Example 1:

[0044] The comparative example also discloses a preparation method of a high-strength aluminum-based composite material, which is basically the same as that of Example 2, and the only difference is that the one-step ball milling step is omitted, the aluminum powder, carbon nanotubes, aluminum-based intermediate alloy powder and SiC powder are all mixed at one time, and then ball milling is directly carried out at a speed of 320 rpm for 6 hours, and then hot pressing sintering and multi-pass hot rolling are carried out.

[0045] Comparative Example 2:

[0046] The comparative example also discloses a preparation method of a high-strength aluminum-based composite material, which is basically the same as that of Example 2, and the only difference is that the aluminum-based intermediate alloy powder containing zirconium and scandium is not added, and the corresponding mass of aluminum powder is supplemented. That is, the composite material does not contain Zr and Sc elements.

[0047] Comparative Example 3:

[0048] The comparative example also discloses a preparation method of a high-strength aluminum-based composite material, which is basically the same as that of Example 2, and the only difference is that the hot rolling process of step (4) is omitted, and the blank obtained by hot pressing sintering is the final material.

[0049] Comparative Example 4:

[0050] The comparative example also discloses a preparation method of a high-strength aluminum-based composite material, which is basically the same as that of Example 2, and the only difference is that before step (1) is carried out, the carbon nanotubes are pretreated: the carbon nanotubes are refluxed in concentrated nitric acid at 120°C for 4 hours for purification and carboxylation, and then washed and dried.

[0051] Comparative Example 5:

[0052] The comparative example also discloses a preparation method of a high-strength aluminum-based composite material, which is basically the same as that of Comparative Example 4, and the only difference is that after the carbon nanotubes are pretreated, they are mixed by the one-step ball milling method of Comparative Example 1.

[0053] Performance test:

[0054] The aluminum-based composite materials prepared in Example 2 and Comparative Examples 1-5 are subjected to mechanical property and physical property tests.

[0055] Mechanical properties: The tensile properties at room temperature, including tensile strength, yield strength and elongation at break, were tested according to GB / T 228.1 standard; the Vickers hardness (HV) was tested according to GB / T 4340.1 standard.

[0056] Physical properties: The thermal diffusivity of the material was tested by laser flash method, and the thermal conductivity was calculated; the electrical conductivity (%IACS) of the material was tested by micro-ohmmeter.

[0057] Performance comparison: The test results are shown in the following table.

[0058] Table 1 Performance comparison results of Example 2 and each comparative example

[0059]

[0060] The experimental data in Table 1 show that the composite material prepared by the method of the application has good performance in various aspects (mechanical and physical properties); Comparative Example 1 (one-step ball milling) and Comparative Example 3 (no hot rolling) mainly have significantly lower mechanical property data, which is considered to be caused by uneven dispersion of the reinforcing body and weak interface bonding, resulting in reduced performance. Comparative Example 4 (increasing acid treatment) has similar strength and hardness index values to Example 2 under the same two-step ball milling process as the application, but the thermal and electrical conductivities are significantly reduced. This phenomenon shows that the acid treatment process may have adversely affected the microstructure of the carbon nanotubes, although the macroscopic mechanical reinforcement effect is maintained, but the functional characteristics as an efficient heat / electricity transmission channel have been significantly restricted. The performance data of Comparative Example 5 (acid treatment combined with one-step ball milling) are all the lowest, indicating that the superimposed effect of chemical damage and mechanical damage causes more serious synergistic damage to the material structure, resulting in a significant reduction in performance.

[0061] In summary, the application synchronously realizes the efficient and uniform dispersion of the reinforcing phase, the strong and tough interface bonding, and the refinement of the matrix grain by two-step ball milling and "micro-alloying" and other means without relying on any chemical modification that may damage the intrinsic structure of the reinforcing body. The method not only solves the classic problem of mutual restriction between strength and plasticity, but also unexpectedly completely retains the excellent thermal and electrical conductivity of carbon nanotubes, and finally successfully prepares a new type of aluminum-based composite material with excellent mechanical properties and outstanding physical properties, which has a broad application prospect.

[0062] The above examples only express several embodiments of the application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are within the scope of protection of the application. Therefore, the protection scope of the application should be subject to the appended claims.

Claims

1. A method of producing a high-strength aluminum matrix composite material, characterized by comprising the steps of: The method comprises the following steps: ​ (1) mixing aluminum powder, carbon nanotubes and aluminum-based intermediate alloy powder by one-step ball milling, the rotation speed of the ball milling is 100-200 rpm, and the ball milling time is 1-3 hours to obtain premixed powder; (2) adding SiC powder into the premixed powder, and then mixing by two-step ball milling, the rotation speed of the ball milling is 250-400 rpm, and the ball milling time is 4-8 hours to obtain composite powder; (3) loading the composite powder into a mold, and performing hot-press sintering under vacuum or inert gas protection, the sintering temperature is 500-580 ℃, the pressure is 30-50 MPa, and the holding time is 0.5-2 hours to obtain a composite material blank; (4) performing multi-pass hot rolling on the composite material blank to obtain the high-strength aluminum-based composite material.

2. The method of claim 1, wherein, In steps (1)-(2), the components are as follows in terms of mass percentage: SiC powder 5-15%, carbon nanotubes 0.5-2%, and aluminum-based intermediate alloy powder, which is an aluminum-based intermediate alloy powder containing zirconium and scandium, provides 0.1-0.5% of Zr element and 0.05-0.2% of Sc element in terms of total mass of the composite material, and the rest is aluminum powder.

3. The method of claim 1, wherein, The particle size of the SiC powder is 1-10 μm, and the tube diameter of the carbon nanotubes is 10-30 nm and the length is 1-10 μm.

4. The method of claim 1, wherein, In steps (1)-(2), the one-step ball milling and the two-step ball milling are both performed under argon protection, and the ball-to-material ratio is 5-10:

1.

5. The method of claim 1, wherein, In step (3), the heating rate of the hot-press sintering is 5-15 ℃ / min.

6. The method of claim 1, wherein, In step (4), the multi-pass hot rolling refers to that the composite material blank is hot-rolled at a temperature of 420-480 ℃, the deformation amount of each pass is controlled to be 10%-15%, the total cumulative deformation amount reaches 60%-80%, and the material is air-cooled to room temperature after the hot rolling is completed.

7. The method of claim 6, wherein, The temperature of the blank is fluctuated by not more than ±20 ℃ by using online induction heating to supplement the temperature between passes.

8. A high-strength aluminum-based composite material prepared by the method of any one of claims 1-7.

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