Wear-resistant high-strength and high-toughness aluminum matrix composite material and preparation method thereof

Abstract

This invention discloses a wear-resistant, high-strength, and high-toughness aluminum-based composite material, comprising an aluminum matrix and a reinforcement; the aluminum matrix has a bimodal grain structure, wherein: the fine grain diameter is ≤1μm, and the coarse grain diameter is ≥4μm; the volume ratio of fine grains to coarse grains in the aluminum matrix is ​​10-30:70-90. Its preparation method includes: (1) preparing flake aluminum alloy powder; (2) mixing the flake aluminum alloy powder with spherical aluminum alloy powder and the reinforcement to obtain a mixed powder; (3) pre-pressing treatment; (4) medium-temperature sintering treatment; (5) medium-temperature large deformation treatment; (6) secondary sintering, thus obtaining the final product. The aluminum-based composite material of this invention, with its bimodal grain structure, combines an aluminum matrix and a reinforcement, which can ensure excellent wear resistance while also possessing high strength and high toughness.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based composite materials, and particularly relates to a wear-resistant, high-strength and tough aluminum-based composite material and its preparation method. Background Technology

[0002] With increasing awareness of carbon neutrality and environmental protection, the development of new energy vehicles is rapid. One of their core goals is to achieve vehicle lightweighting to improve fuel efficiency and reduce carbon emissions. Lightweighting places higher demands on the performance and density of automotive materials, and aluminum and aluminum-based composites have attracted much attention due to their excellent specific strength, thermal conductivity, and corrosion resistance. Lightweighting can not only extend the driving range of electric vehicles but also improve the fuel efficiency of internal combustion engine vehicles. The low density and high thermal conductivity of aluminum and aluminum-based composites make them ideal for manufacturing engine and transmission system components, reducing power loss and improving power transmission efficiency. Replacing traditional wear-resistant cast iron (HT250) and steel components with aluminum and aluminum-based composites, which have excellent thermal conductivity and thermal stability, to manufacture lightweight brake discs, battery trays, etc., can improve braking performance and reduce braking distance, significantly reduce the overall vehicle weight, and thus enhance driving safety.

[0003] Traditional methods for preparing wear-resistant aluminum-based composite materials include stirred / extrusion casting, spray deposition, and powder metallurgy. Due to the poor wettability between ceramic particles and molten aluminum alloy, reinforcing phase particles tend to agglomerate in the molten aluminum during casting, leading to decreased material uniformity and performance (e.g., patents CN 115094280A; CN 115058619A; 115505779A). Spray deposition involves using a high-pressure inert gas to create a mist-like jet of liquid metal, simultaneously injecting reinforcing particles into the jet of molten alloy. This mixes the two phases and co-deposits them onto a pretreated substrate, rapidly solidifying to prepare particle-reinforced aluminum-based composite materials. However, this method suffers from low reinforcing particle utilization, high preparation costs, and low density, requiring secondary processing. Powder metallurgy avoids the interface problems between reinforcing phase particles and the aluminum matrix, allowing for more uniform dispersion of reinforcing phase particles and improving material uniformity and performance. Simultaneously, powder metallurgy allows for more precise control of alloy composition, ensuring materials meet specific requirements. Furthermore, aluminum-based composites prepared by powder metallurgy typically exhibit higher plasticity, making them easier to form and process. Finally, powder metallurgy allows for the fabrication of complex-shaped parts, expanding the material's application areas. Therefore, aluminum-based composites prepared by powder metallurgy have potentially broad application prospects, particularly in meeting the lightweight requirements of new energy vehicles, offering greater flexibility and performance advantages.

[0004] Although some patents have used powder metallurgy to prepare aluminum-based composite materials (such as CN 116426795 A; CN116604019A, etc.), their strength is difficult to exceed 450 MPa, or when the strength reaches that level, due to the excessive addition of ceramic reinforcing phase, it has almost no plasticity. Summary of the Invention

[0005] To address the aforementioned technical issues, this invention provides a wear-resistant, high-strength, and high-toughness aluminum-based composite material and its preparation method. The aluminum-based composite material possesses both wear resistance and high strength and toughness.

[0006] The specific solution of this invention is as follows:

[0007] One objective of this invention is to provide a wear-resistant, high-strength, and high-toughness aluminum-based composite material, comprising an aluminum matrix and a reinforcement; wherein the aluminum matrix has a bimodal grain structure, wherein the fine grain diameter is ≤1μm and the coarse grain diameter is ≥4μm; and the volume ratio of fine grains to coarse grains in the aluminum matrix is ​​10-30:70-90.

[0008] Preferably, the aluminum matrix is ​​pure aluminum or an aluminum alloy.

[0009] Preferably, the reinforcement accounts for 0.5%-12.5% ​​of the mass of the aluminum matrix composite.

[0010] Preferably, the reinforcing agent is selected from one or more combinations of silicon carbide, titanium carbide, boron carbide, aluminum oxide, titanium oxide, and titanium boride.

[0011] This invention combines an aluminum matrix with a bimodal grain structure with a reinforcement, which can ensure excellent wear resistance while also possessing high strength and high toughness.

[0012] The second objective of this invention is to provide a method for preparing a wear-resistant, high-strength, and tough aluminum-based composite material, comprising: (1) ball milling spherical aluminum alloy powder to obtain flake aluminum alloy powder; (2) mixing the flake aluminum alloy powder with spherical aluminum alloy powder and a reinforcing body to obtain a mixed powder; (3) pre-pressing the mixed powder to obtain ingot I; (4) sintering ingot I at a medium temperature of 350-450℃ for 1-15 minutes to obtain ingot II; (5) after the temperature of ingot II drops to 250-400℃, performing a medium-temperature large deformation treatment at this temperature to obtain ingot III; (6) performing a second sintering on ingot III to obtain the final product.

[0013] Preferably, in step (1), the ball milling rate is ≤100 r / min, and the ball milling time is 10-40 h; the thickness of the flake aluminum alloy powder is 0.5-1 μm. More preferably, the ball milling rate is 20-50 r / min.

[0014] Preferably, in step (2), the mass percentage of the mixed powder is 15-25% of the flake aluminum alloy powder, the mass percentage of the reinforcement is 0.5-12.5%, and the remainder is spherical aluminum alloy powder.

[0015] The preparation method of spherical aluminum alloy powder in the mixed powder is not specifically limited, including but not limited to obtaining it by atomization.

[0016] Preferably, in step (2), the particle size of the spherical aluminum alloy powder is 1-100 μm; the particle size of the reinforcement is 1-8 μm.

[0017] Preferably, in step (2), the mixing method is ball milling.

[0018] Preferably, in step (3), the density of the pre-pressed billet I is 45-65%.

[0019] Preferably, in step (4), the medium-temperature sintering method is selected from either hot pressing sintering or hot pressing discharge sintering.

[0020] Preferably, in step (5), the medium-temperature large deformation method is selected from one or more combinations of forging, extrusion, and rolling; more preferably, the total deformation is 50-90%.

[0021] This invention employs a medium-temperature sintering process (sintering temperature 350-450℃) and a medium-temperature large deformation process (sintering temperature 250-400℃). The medium-temperature sintering process can increase the density of the composite material while retaining the high-density dislocation characteristics of the lamellar aluminum alloy powder. On this basis, the medium-temperature large deformation process further enhances the density of the aluminum-based composite material. Furthermore, due to the unavoidable oxide film (composed of Al2O3) on the surface of the aluminum powder or aluminum alloy powder, the oxide film breaks down and becomes uniformly distributed during the medium-temperature large deformation process, resulting in a dispersion strengthening effect.

[0022] Preferably, in step (6), the temperature of the secondary sintering is 500-630℃ and the sintering time is 0.5-12h.

[0023] The beneficial effects of this invention are:

[0024] The aluminum-based composite material provided by the present invention comprises an aluminum matrix and a reinforcement with a bimodal grain structure. The aluminum-based composite material has both wear resistance and excellent high strength and high toughness, and can be widely used in wear-resistant and lightweight structures.

[0025] This invention also provides a method for preparing the aluminum-based composite material, which involves mixing lamellar aluminum alloy powder with high dislocation density, spherical aluminum alloy powder, and reinforcement in a certain proportion, and combining this with medium-temperature sintering and medium-temperature large deformation treatment processes. This not only achieves the preparation of an aluminum matrix with a bimodal grain structure, but also effectively utilizes the alumina on the surface of the aluminum alloy powder to reinforce and refine the matrix, which helps to maintain the ultrafine grain and wear-resistant properties of the aluminum-based composite material. Attached Figure Description

[0026] Figure 1 The image shows the SEM morphology of the sheet-like aluminum alloy powder obtained in step (1) of Example 1.

[0027] Figure 2 The image shows the SEM morphology of the mixed powder obtained in step (2) of Example 1.

[0028] Figure 3 The image shows the EBSD microstructure of the bimodal grain structure of the aluminum-based composite material prepared in Example 1.

[0029] Figure 4 The image shows the SEM morphology of the mixed powder obtained in step (2) of Example 2.

[0030] Figure 5 The image shows the EBSD microstructure of the bimodal grain structure of the aluminum-based composite material prepared in Example 2.

[0031] Figure 6 EBSD image of the microstructure of the aluminum-based composite material prepared in Comparative Example 1;

[0032] Figure 7 SEM image of the aluminum-based composite material prepared in Comparative Example 2; Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0034] Example 1

[0035] A wear-resistant, high-strength, and high-toughness aluminum-based composite material includes an aluminum matrix and a silicon carbide reinforcement; the aluminum matrix has a bimodal grain structure, wherein: the diameter of fine grains in the aluminum matrix is ​​≤1μm, and the diameter of coarse grains is ≥4μm; the volume ratio of fine grains to coarse grains is 15:80; and the reinforcement accounts for 5% of the mass of the aluminum-based composite material.

[0036] It is prepared according to the following method:

[0037] (1) Preparation of flake aluminum alloy powder: The spherical 2024 aluminum alloy powder obtained by atomization powdering was ball-milled in a low-speed ball milling device at a ball milling rate of 30 r / min for 15 hours to obtain flake aluminum alloy powder with an average thickness of 0.8 μm.

[0038] The SEM image of the flake aluminum alloy powder is as follows: Figure 1 As shown;

[0039] (2) Powder mixing: The obtained flake aluminum alloy powder is ball-milled and mixed with spherical aluminum alloy powder and reinforcing silicon carbide particles in a certain proportion to obtain mixed powder; in the mixed powder, the flake aluminum alloy powder accounts for 15%, silicon carbide accounts for 5%, and the remainder is spherical aluminum alloy powder; the particle size of the spherical aluminum alloy powder is 1-100μm, and the average particle size of the silicon carbide particles is 3μm.

[0040] The SEM image of the mixed powder is as follows: Figure 2 As shown;

[0041] (3) Pre-pressing: The mixed powder is pre-pressed at room temperature using a grinding wheel to obtain billet I with a density of 50%;

[0042] (4) Medium-temperature sintering: Ingot I is subjected to medium-temperature vacuum sintering at a temperature of 400℃ for 3 minutes and a pressure of 50MPa to obtain ingot II.

[0043] (5) Medium temperature large deformation: After the blank II is opened, wait for the temperature of blank II to drop to 330℃, and then perform medium temperature extrusion treatment. The extrusion ratio is 5:1 (the total deformation is equivalent to 80%) to obtain blank III.

[0044] (6) Secondary sintering: The billet III is sintered twice at a temperature of 500℃ for 1 hour to obtain wear-resistant, high-strength and tough aluminum-based composite material.

[0045] The wear-resistant, high-strength, and tough aluminum-based composite material prepared in this embodiment has a tensile strength of 465 MPa, a Brinell hardness of 145, and an elongation after fracture of 17%. Its microstructure consists of coarse and fine disc-shaped grains with a bimodal scale. Figure 3 As shown.

[0046] Example 2

[0047] A wear-resistant, high-strength, and high-toughness aluminum-based composite material includes an aluminum matrix and a silicon carbide reinforcement. The aluminum matrix has a bimodal grain structure, wherein: the diameter of fine grains in the aluminum matrix is ​​≤1μm, and the diameter of coarse grains is ≥4μm; the volume ratio of fine grains to coarse grains in the aluminum matrix is ​​20:70; and the reinforcement accounts for 10% of the mass of the aluminum-based composite material.

[0048] It is prepared according to the following method:

[0049] (1) Preparation of sheet-like aluminum alloy powder: Same as in Example 1;

[0050] (2) Powder Mixing: The obtained flake aluminum alloy powder, spherical aluminum alloy powder, and reinforcing silicon carbide particles are ball-milled and mixed in a certain proportion to obtain a mixed powder; in the mixed powder, the flake aluminum alloy powder accounts for 20%, silicon carbide accounts for 10%, and the remainder is spherical aluminum alloy powder; the particle size of the spherical aluminum alloy powder is 1-100 μm, and the average particle size of the silicon carbide particles is 3 μm; the SEM image of the mixed powder is shown below. Figure 4 As shown;

[0051] (3) Pre-pressing: The mixed powder is pre-pressed at room temperature using a grinding wheel to obtain billet I with a density of 50%;

[0052] (4) Medium-temperature sintering: Ingot I is subjected to medium-temperature vacuum sintering at a temperature of 450°C for 3 minutes and a pressure of 50MPa to obtain ingot II.

[0053] (5) Medium temperature large deformation: After the billet II in step (4) is opened, the billet II temperature is reduced to 350℃ and medium temperature extrusion is carried out. The extrusion ratio is 8:1 (the total deformation is equivalent to 87.5%), and billet III is obtained.

[0054] (6) Secondary sintering: The billet III is sintered twice at a temperature of 530℃ for 1 hour to obtain wear-resistant, high-strength and tough aluminum-based composite material.

[0055] The wear-resistant, high-strength, and tough aluminum-based composite material prepared in this embodiment has a tensile strength of 520 MPa, a Brinell hardness of 158, and an elongation after fracture of 12%. Its microstructure consists of coarse and fine disc-shaped grains with a bimodal scale. Figure 5 As shown.

[0056] Comparative Example 1

[0057] A method for preparing an aluminum-based composite material, comprising:

[0058] Steps (1)-(3): Same as in Example 1, obtain billet I; (4) Sinter billet I at a sintering temperature of 500℃ for 1 hour to obtain aluminum-based composite material.

[0059] The aluminum-based composite material prepared in this comparative example achieved a tensile strength of 385 MPa and a Brinell hardness of 126, both lower than those of Example 1. Furthermore, its elongation after fracture was only 7%, significantly lower than the 17% of Example 1. Its microstructure, characterized by EBSD, consisted of equiaxed large grains with indistinct bimodal grains. Figure 6 As shown.

[0060] It can be seen that the aluminum-based composite material obtained using the same mixed powder composition under the process conditions of single pre-pressing + single sintering has lower tensile strength, hardness, and elongation after fracture than that of Example 1. The composite material obtained by combining "pre-pressing" with "medium-temperature sintering" and "medium-temperature large deformation" processes is also problematic. Furthermore, the single pre-pressing + single sintering process cannot achieve a microstructure with a mixture of coarse and fine grains.

[0061] Comparative Example 2

[0062] A method for preparing an aluminum-based composite material, comprising:

[0063] Steps (1)-(3): Same as in Example 1, obtain billet I; (4) Sinter billet I at a sintering temperature of 500℃ for 1 hour. When the billet temperature drops to 400℃, perform forging and extrusion treatment at a forging-extrusion ratio of 5:1 to obtain aluminum-based composite material.

[0064] The aluminum-based composite material prepared in this comparative example achieved a tensile strength of 485 MPa, a Brinell hardness of 150, and an elongation after fracture of 3%. Its strength and hardness were slightly higher than those of Example 1, but its plasticity was only 3%, significantly lower than the 17% in Example 1. Its microstructure, characterized by scanning electron microscopy (SEM), exhibited a fibrous deformed shape and lacked equiaxed bimodal grain characteristics. Figure 7 As shown.

[0065] Given that the comparative example directly employs a one-step high-temperature sintering process at 500℃ for 1 hour, this high temperature directly destroys the high-density dislocation structure within the special lamellar spherical powder, thus preventing the formation of a bimodal grain structure in the aluminum matrix. Furthermore, since the aluminum-based composite material is ultimately in an extruded state under this process, and because micron-sized reinforcing phase particles (rather than nano-sized reinforcing phases) are added as a hard, wear-resistant phase, although the hardness increases slightly, the scanning electron microscopy morphology shows insufficient bonding strength between the hard particles and the aluminum matrix, which is detrimental to the overall strength and toughness of the aluminum-based composite material.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A wear-resistant, high-strength, and high-toughness aluminum-based composite material, characterized in that, The material comprises an aluminum matrix and a reinforcement; the aluminum matrix has a bimodal grain structure, wherein: the fine grain diameter is ≤1μm, and the coarse grain diameter is ≥4μm; the volume ratio of fine grains to coarse grains in the aluminum matrix is ​​10-30:70-90; the reinforcement accounts for 0.5%-12.5% ​​of the mass of the aluminum matrix composite material; The preparation method includes: (1) ball milling spherical aluminum alloy powder to obtain flake aluminum alloy powder; the thickness of the flake aluminum alloy powder is 0.5-1μm; (2) mixing the flake aluminum alloy powder with spherical aluminum alloy powder and reinforcement to obtain mixed powder; in the mixed powder, the mass percentage of flake aluminum alloy powder is 15-25%, the mass percentage of reinforcement is 0.5-12.5%, and the remainder is spherical aluminum alloy powder; (3) pre-pressing the mixed powder to obtain billet I; the density of the pre-pressed billet I is 45-65%; (4) sintering billet I at a medium temperature of 350-450℃ for 1-15min to obtain billet II; (5) when the temperature of billet II drops to 250-400℃, performing a medium temperature large deformation treatment at this temperature to obtain billet III; the total deformation is 50-90%; (6) performing secondary sintering on billet III to obtain the final product.

2. The wear-resistant, high-strength, and high-toughness aluminum-based composite material according to claim 1, characterized in that, The reinforcing agent is selected from one or more combinations of silicon carbide, titanium carbide, boron carbide, aluminum oxide, titanium oxide, and titanium boride.

3. The method for preparing the wear-resistant, high-strength, and tough aluminum-based composite material according to claim 1 or 2, characterized in that, include: (1) Ball mill the spherical aluminum alloy powder to obtain flake aluminum alloy powder; (2) Mix the flake aluminum alloy powder with the spherical aluminum alloy powder and the reinforcement to obtain a mixed powder; (3) Pre-press the mixed powder to obtain billet I; (4) Sinter billet I at 350-450℃ for 1-15 min to obtain billet II; (5) When the temperature of billet II drops to 250-400℃, perform medium-temperature large deformation treatment at this temperature to obtain billet III; (6) Perform secondary sintering on billet III to obtain the final product.

4. The method of making a wear resistant high strength to toughness aluminum matrix composite of claim 3, wherein, In step (1), the ball milling rate is ≤100r / min and the ball milling time is 10-40h.

5. The method of making a wear-resistant high strength-to-ductility aluminum matrix composite of claims 3 or 4, wherein, In step (2), the particle size of the spherical aluminum alloy powder is 1-100 μm; the particle size of the reinforcement is 1-8 μm; and the mixing method is ball milling.

6. The method for preparing the wear-resistant, high-strength, and tough aluminum-based composite material according to claim 3 or 4, characterized in that, In step (4), the medium-temperature sintering method is selected from either hot pressing sintering or hot pressing discharge sintering; in step (5), the medium-temperature large deformation method is selected from one or more combinations of forging, extrusion, and rolling.

7. The method of making a wear-resistant, high-strength-to-toughness aluminum matrix composite of claims 3 or 4, wherein, The secondary sintering temperature is 500-630℃, and the sintering time is 0.5-12h.

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