Aluminum-based composite material with multi-level heterogeneous structure and preparation method thereof

Abstract

The present invention discloses an aluminum-based composite material with a multi-level heterogeneous structure and a preparation method thereof, belonging to the technical field of metal-based composite materials. The present invention uses aluminum powder, magnesium powder, stearic acid, and copper oxide powder as raw materials and employs segmented ball milling. By regulating the difference in defect density between the interface and the interior, a grain heterogeneous structure is obtained, forming a heterogeneous lamellar structure with coarse-grained bands embedded in fine-grained regions. Simultaneously, under the influence of the reaction heat effect during the second ball milling process and the original distribution position of CuO, MgO particles are primarily distributed within the grains in the fine-grained region, thereby obtaining an aluminum-based composite material with a multi-level heterogeneous structure. The precipitation of the precipitated phase is then regulated through a subsequent heat treatment process, resulting in an aluminum-based composite material with high strength and plasticity.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-based composite materials, and in particular relates to an aluminum-based composite material with a multi-level heterogeneous structure and a preparation method thereof. Background Art

[0002] Aluminum-based composites, with their excellent properties of low density and high specific strength, hold broad application prospects in aerospace, electronics, and power generation. While the introduction of reinforcements increases the strength of aluminum-based composites, it also significantly reduces their ductility. Therefore, overcoming the inverse strength-ductility / toughness trade-off in aluminum-based composites is a pressing scientific challenge.

[0003] Existing patent CN109082568A discloses a method for preparing an in-situ synthesized nano-CuAl2 / Al2O3 reinforced aluminum-based composite material. The method involves ball-milling aluminum powder and copper oxide powder and sintering the resulting material to produce an aluminum-based composite material with excellent performance. However, this method still fails to address the inverse relationship between strength and plasticity in aluminum-based composite materials. Existing studies have shown that the introduction of alloying elements can change the type of reinforcement phase and precipitate phase precipitation, effectively strengthening the aluminum-based composite material system. The addition of Mg not only forms an MgO reinforcement phase that is coherently matched with the aluminum matrix and significantly reduces its size, but also, under certain conditions, can form a multicomponent precipitate phase, thereby improving the mechanical properties of the composite material. However, the Al-Mg-CuO system formed after the introduction of Mg still suffers from the problem of being unable to simultaneously achieve high strength and plasticity.

[0004] Therefore, how to prepare aluminum-based composite materials with both high strength and plasticity has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes an aluminum-based composite material with a multi-level heterogeneous structure and a preparation method thereof.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing an aluminum-based composite material having a multi-level heterogeneous structure, comprising the following steps:

[0008] (1) Aluminum powder, magnesium powder, and stearic acid are mixed and subjected to a first ball milling process under a protective atmosphere to obtain cold welding alloy particles; the cold welding alloy particles are mixed with copper oxide powder and subjected to a second ball milling process to obtain a composite powder;

[0009] (2) The composite powder obtained in step (1) is sequentially subjected to cold pressing, sintering, hot extrusion, solution treatment and aging treatment to obtain an aluminum-based composite material with a multi-level heterogeneous structure.

[0010] Preferably, in step (1), the mass ratio of the aluminum powder, magnesium powder, copper oxide powder and stearic acid is (18.2-18.4):0.8:(0.8-1):(0.1-0.15).

[0011] Preferably, in step (1), the ball milling parameters of the first ball milling treatment and the second ball milling treatment are independently: ball-to-material ratio is (10:1) to (15:1), rotation speed is 500 rpm / min, and time is 6 to 8 hours.

[0012] Preferably, in step (2), the cold pressing pressure is 600 MPa and the holding time is 3 minutes.

[0013] Preferably, in step (2), the sintering heating rate is 10K / min, the temperature is 863K, and the holding time is 1 to 2 hours.

[0014] Preferably, in step (2), the hot extrusion temperature is 843K, the holding time is 40 min, the pressure is 750 MPa, and the extrusion ratio is 16:1.

[0015] Preferably, in step (2), the temperature of the solution treatment is 793K, the holding time is 4h, and the cooling method is water quenching.

[0016] Preferably, in step (2), the aging treatment is performed at a temperature of 408 K and for a time of 24 h.

[0017] The present invention also provides an aluminum-based composite material with a multi-level heterogeneous structure prepared by the preparation method described in the above technical solution.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention uses aluminum powder, magnesium powder, stearic acid and copper oxide powder as raw materials and adopts segmented ball milling. The heterogeneous structure of grains can be obtained by regulating the defect density difference between the interface and the interior, forming a heterogeneous lamellar structure in which coarse-grained bands are embedded in fine-grained areas. At the same time, under the influence of the reaction heat effect in the second ball milling process and the original distribution position of CuO, MgO particles are mainly distributed inside the grains in the fine-grained area, thereby obtaining an aluminum-based composite material with a multi-level heterogeneous structure. The precipitation of the precipitated phase Al2Cu is regulated through a subsequent heat treatment process, thereby obtaining an aluminum-based composite material with high strength and plastic toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0021] Figure 1This is a process flow chart of Example 1;

[0022] Figure 2 The morphology of the cold-welded alloy particles (a) in step (1) of Example 1 and the non-cold-welded alloy particles (b) in Comparative Example 1;

[0023] Figure 3 EBSD images of the aluminum-based composite materials prepared in Example 1 and Comparative Example 1;

[0024] Figure 4 The engineering stress-strain curves of the aluminum-based composite materials prepared in Example 1 and Comparative Examples 1-2 are shown. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] An embodiment of the present invention provides a method for preparing an aluminum-based composite material having a multi-level heterogeneous structure, comprising the following steps:

[0028] (1) Aluminum powder, magnesium powder, and stearic acid are mixed and subjected to a first ball milling process under a protective atmosphere to obtain cold welding alloy particles; the cold welding alloy particles are mixed with copper oxide powder and subjected to a second ball milling process to obtain a composite powder;

[0029] (2) The composite powder obtained in step (1) is sequentially subjected to cold pressing, sintering, hot extrusion, solution treatment and aging treatment to obtain an aluminum-based composite material with a multi-level heterogeneous structure.

[0030] In a preferred embodiment, in step (1), the mass ratio of the aluminum powder, magnesium powder, copper oxide powder, and stearic acid is (18.2-18.4):0.8:(0.8-1):(0.1-0.15). The present invention controls the amount of aluminum powder, magnesium powder, copper oxide powder, and stearic acid within the above range, which is beneficial for improving the strength-ductility matching relationship of the aluminum-based composite material with a multi-level heterogeneous structure. The stearic acid in the present invention is used to control the degree of cold welding of the alloy powder. Changing the amount of stearic acid will not result in cold-welded alloy particles.

[0031] The magnesium powder in the present invention can not only form an MgO reinforcement phase that is coherently matched with the aluminum matrix, but also form a multi-element precipitation phase, thereby improving the mechanical properties of the aluminum-based composite material; the copper oxide powder can be uniformly dispersed on the surface of the cold-welded alloy particles during the ball milling process, and combined with the reaction heat effect during the second ball milling process, the MgO particles are mainly distributed inside the grains in the fine-grained area, thereby obtaining an aluminum-based composite material with a multi-level heterogeneous structure; at the same time, O atoms can be provided through a replacement reaction, and a precipitation phase Al2Cu can be precipitated through subsequent heat treatment and aging; stearic acid is used as a process control agent to regulate the structure of the aluminum-based composite material, so as to obtain a heterogeneous lamellar grain structure with fine grains embedded in coarse grain bands.

[0032] In a preferred embodiment, in step (1), the purity of the aluminum powder is 99.9%; the purity of the magnesium powder is 99.9%; and the purity of the copper oxide powder is 99.9%.

[0033] In a preferred embodiment, in step (1), the milling parameters for the first and second ball milling processes are independently: a ball-to-material ratio of (10:1) to (15:1), a rotation speed of 500 rpm / min, and a time of 6 to 8 hours. The aluminum-based composite material prepared under these ball milling conditions has good strength and plasticity.

[0034] In a preferred embodiment, in step (1), the protective atmosphere is argon. In the present invention, the first ball milling is performed under a protective atmosphere to prevent the aluminum powder and the magnesium powder from being oxidized.

[0035] The present invention involves a first ball milling process under a protective atmosphere, mechanically alloying aluminum and magnesium powders under the control of stearic acid. Copper oxide powder is then added for a second ball milling process, achieving microstructural control of the composite powder and producing a heterogeneous lamellar grain structure with fine grains embedded in coarse grain bands. Simultaneously, a nano-MgO reinforcement phase is generated in situ within the aluminum matrix grains through a solid-phase in-situ reaction.

[0036] In a preferred embodiment, in step (2), the cold pressing pressure is 600 MPa, the holding time is 3 minutes, and the pressurizing equipment is a hydraulic press. The present invention performs cold pressing under the above cold pressing pressure and holding time, which is conducive to obtaining a dense aluminum-based composite material block.

[0037] In a preferred embodiment, in step (2), the sintering is performed at a heating rate of 10 K / min, a temperature of 863 K, a holding time of 1 to 2 hours, and an argon atmosphere in a tubular furnace. The present invention facilitates sintering under these sintering conditions to obtain a sintered aluminum-based composite material with excellent tensile properties.

[0038] In a preferred embodiment, in step (2), the hot extrusion temperature is 843K, the holding time is 40 minutes, the pressure is 750 MPa, and the extrusion ratio is 16: 1. The present invention performs hot extrusion under the above hot extrusion conditions, which is beneficial to improving the tensile properties of the aluminum-based composite material.

[0039] In a preferred embodiment, in step (2), the temperature of the solution treatment is 793K, the holding time is 4 hours, and the cooling method is water quenching.

[0040] In a preferred embodiment, in step (2), the aging treatment temperature is 408K, the time is 24 hours, and the cooling method is air cooling.

[0041] The present invention regulates the precipitation of the precipitate phase through solution treatment and aging treatment, which is conducive to obtaining an aluminum-based composite material with high strength and plasticity and toughness.

[0042] The present invention also provides an aluminum-based composite material with a multi-level heterogeneous structure prepared by the preparation method described in the above technical solution.

[0043] The aluminum-based composite material with a multi-level heterogeneous structure provided by the present invention has high strength and plastic toughness.

[0044] The room temperature in the embodiments of the present invention refers to "25±2°C".

[0045] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0046] Example 1

[0047] A method for preparing an aluminum-based composite material with a multi-level heterogeneous structure, the process flow is as follows Figure 1 The specific steps are as follows:

[0048] (1) 18.2 g of aluminum powder, 0.8 g of magnesium powder, and 0.11 g of stearic acid were placed in a 250 mL ball mill and subjected to the first ball milling treatment under argon protection. The ball milling parameters were as follows: the ball-to-material ratio was 15:1, the ball milling speed was 500 rpm / min, and the ball milling time was 8 h to obtain cold-welded alloy particles. 1.0 g of copper oxide powder was then added to the cold-welded alloy particles and subjected to the second ball milling treatment. The ball milling parameters were as follows: the ball-to-material ratio was 15:1, the ball milling speed was 500 rpm / min, and the ball milling time was 6 h to obtain a composite powder.

[0049] (2) The composite powder obtained in step (1) is placed in a cold pressing mold, a pressure of 600 MPa is applied using a hydraulic press, the pressure is maintained for 3 minutes, and then the composite powder is placed in a tubular furnace with argon gas for sintering. After the sintering is completed, it is hot extruded in a conical extrusion mold to obtain an aluminum-based composite material block with a multi-level heterogeneous structure; the sintering process parameters are: heating rate 10K / min, temperature 863K, holding time 1h; the hot extrusion process parameters are: temperature 843K, holding time 40min, pressure 750MPa, extrusion ratio 16:1.

[0050] (3) The aluminum-based composite material block with a multi-level heterogeneous structure obtained in step (2) is solutionized at 793K for 4 hours and water quenched, then aged at 408K for 24 hours and air-cooled to obtain an aluminum-based composite material with a multi-level heterogeneous structure.

[0051] Comparative Example 1

[0052] (1) 18.2 g of aluminum powder, 0.8 g of magnesium powder, and 0.2 g of stearic acid were placed in a 250 mL ball mill and subjected to a first ball milling process under argon protection. The ball milling parameters were: ball-to-material ratio of 15:1, ball milling speed of 500 rpm / min, and ball milling time of 8 h to obtain un-cold-welded alloy particles. 1.0 g of copper oxide powder was then added to the un-cold-welded alloy particles and subjected to a second ball milling process. The ball milling parameters were: ball-to-material ratio of 15:1, ball milling speed of 500 rpm / min, and ball milling time of 6 h to obtain a composite powder.

[0053] Steps (2)-(3) are the same as in Example 1.

[0054] Comparative Example 2

[0055] (1) 18.4 g aluminum powder, 0.8 g magnesium powder and 0.11 g stearic acid were placed in a 250 mL ball mill and subjected to the first ball milling treatment under argon protection. The ball milling parameters were as follows: the ball-to-material ratio was 15:1, the ball milling speed was 500 rpm / min, and the ball milling time was 8 h to obtain cold-welded alloy particles. 0.8 g copper powder was then added to the cold-welded alloy particles and subjected to the second ball milling treatment. The ball milling parameters were as follows: the ball-to-material ratio was 15:1, the ball milling speed was 500 rpm / min, and the ball milling time was 6 h to obtain a composite powder.

[0056] Steps (2)-(3) are the same as in Example 1.

[0057] Figure 2 The morphology of the cold-welded alloy particles (a) in step (1) of Example 1 and the uncold-welded alloy particles (b) in step (1) of Comparative Example 1 is shown in FIG. Figure 2 It can be seen that the cold-welded alloy particles are welded together in a block shape due to the mechanical alloying during the ball milling process.

[0058] Figure 3 EBSD images of the aluminum-based composite materials prepared in Example 1 and Comparative Example 1, wherein (a) is Comparative Example 1 and (b) is Example 1. Figure 3 It can be seen that the aluminum-based composite material prepared in Example 1 has a multi-level heterogeneous structure with fine grains embedded in coarse grain bands, while the aluminum-based composite material prepared in Comparative Example 1 has a uniform structure.

[0059] The aluminum-based composite materials prepared in Example 1 and Comparative Examples 1-2 were subjected to wire cutting to be processed into standard tensile specimens, and the tensile properties were tested on a universal tensile testing machine at a tensile rate of 0.5 mm / min. The test results are shown in FIG. Figure 4 .

[0060] Figure 4 The engineering stress-strain curves of the aluminum-based composite materials prepared in Example 1 and Comparative Examples 1-2 are shown.

[0061] Among them, the multi-level heterogeneous structure is Example 1, the uniform structure is Comparative Example 1, and the alloy is Comparative Example 2. Figure 4 It can be seen that the aluminum-based composite material with a multi-level heterogeneous structure prepared by the present invention has an excellent strength-ductility matching relationship and has excellent work hardening ability.

[0062] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing an aluminum-based composite material having a multi-level heterogeneous structure, characterized in that: The following steps are involved: (1) Aluminum powder, magnesium powder and stearic acid are mixed and subjected to a first ball milling treatment under a protective atmosphere to obtain cold welding alloy particles; the cold welding alloy particles are mixed with copper oxide powder and subjected to a second ball milling treatment to obtain a composite powder; the mass ratio of the aluminum powder, magnesium powder, copper oxide powder and stearic acid is (18.2-18.4):0.8:(0.8-1):(0.1-0.15); the ball milling parameters of the first ball milling treatment and the second ball milling treatment are independently: the ball-to-material ratio is (10:1)-(15:1), the rotation speed is 500 rpm, and the time is 6-8 hours; (2) The composite powder obtained in step (1) is sequentially subjected to cold pressing, sintering, hot extrusion, solution treatment and aging treatment to obtain an aluminum-based composite material with a multi-level heterogeneous structure.

2. The method for preparing an aluminum-based composite material having a multi-level heterogeneous structure according to claim 1, wherein: In step (2), the cold pressing pressure is 600 MPa and the holding time is 3 minutes.

3. The method for preparing an aluminum-based composite material having a multi-level heterogeneous structure according to claim 1, wherein: In step (2), the sintering heating rate is 10K / min, the temperature is 863K, and the holding time is 1 to 2 hours.

4. The method for preparing an aluminum-based composite material having a multi-level heterogeneous structure according to claim 1, wherein: In step (2), the hot extrusion temperature is 843K, the holding time is 40min, the pressure is 750MPa, and the extrusion ratio is 16:

1.

5. The method for preparing an aluminum-based composite material having a multi-level heterogeneous structure according to claim 1, wherein: In step (2), the temperature of the solution treatment is 793K, the holding time is 4h, and the cooling method is water quenching.

6. The method for preparing an aluminum-based composite material having a multi-level heterogeneous structure according to claim 1, wherein: In step (2), the aging treatment temperature is 408K and the time is 24h.

7. An aluminum-based composite material with a multi-level heterogeneous structure prepared by the preparation method according to any one of claims 1 to 6.

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