Low-density high-strength aluminum-based composite material and preparation method thereof

Abstract

The invention provides a low-density high-strength aluminum-based composite material and a preparation method, and relates to the technical field of aluminum alloy powder metallurgy preparation. The composite material is composed of two parts: a matrix alloy and hollow glass beads, wherein the addition amount of the hollow glass beads is 5-30 wt.%. The matrix alloy comprises the following components in percentage by mass: 0 to 6.0 percent of Cu, 0 to 3.0 percent of Mg, 0 to 8.4 percent of Zn and the balance of Al and inevitable impurities; the hollow glass beads are prepared from the following components in percentage by mass: 70 to 80 percent of SiO2, 8 to 15 percent of CaO, 5 to 15 percent of Na2O, 3 to 8 percent of B2O3 and 2 to 3 percent of Al2O3. The composite material is prepared through surface modification of hollow glass beads, preparation of composite powder, preparation of a composite material green body, sintering densification, deformation processing and heat treatment. According to the technology, low-cost preparation and processing of the low-density and high-strength aluminum-based composite material can be achieved, the technological process is simple, the production efficiency is high, the method is suitable for large-scale industrial production, and the application prospects in the fields of aerospace, new energy automobiles, ships, electronic communication and the like are huge.

Description

Technical Field

[0001] This invention relates to the technical field of aluminum alloy powder metallurgy preparation, and in particular to a low-density, high-strength aluminum-based composite material and its preparation method. Background Technology

[0002] High-performance aluminum alloys, with their lightweight, high strength, wear resistance, corrosion resistance, excellent impact resistance and energy absorption capacity, and extremely high recyclability, have become key materials for lightweight development in aerospace, new energy vehicles, and 3C products. However, to continuously improve service performance, the future demand for further lightweighting in aerospace and automotive fields is extremely urgent, and the weight reduction effect of existing aluminum alloys by adjusting composition has reached its limit. Compared with traditional aluminum alloy materials, aluminum-based composite materials have a wider design space. Different reinforcing phase materials and different component ratios can be used to produce aluminum-based composite materials with better microstructure and performance by using different synthesis methods according to the required performance. These composite materials have excellent properties such as low specific gravity, high strength, low coefficient of thermal expansion, and convenient forming and processing.

[0003] Hollow glass microspheres are an ideal ultra-low density reinforcing material. Their thin shells provide support, and the pore size can be controlled by adjusting the diameter of the hollow microspheres, thus improving the dimensional stability of the material. Hollow microspheres are lightweight, have good electrical insulation and thermal stability, strong wear resistance, and high compressive strength. As the second phase in aluminum-based composite materials, they can significantly reduce the density of the composite material.

[0004] For example, Chinese patent CN115305377A discloses a method for preparing an aluminum-based hollow glass microsphere porous composite material. This method uses a semi-solid stirring casting process. By controlling the stirring temperature, stirring speed, and stirring time, a hollow glass microsphere / 2024Al porous composite material with relatively uniform distribution and excellent performance is obtained. Although it can solve the problems of high cost and difficulty in meeting multifunctional requirements of traditional foamed aluminum to a certain extent, the wettability between hollow glass microspheres and 2024Al melt is poor, making it difficult to further improve casting performance. At the same time, this invention technology has high equipment requirements, and the size of the prepared billet is limited, making it difficult to meet the manufacturing needs of large-size aluminum-based composite material components.

[0005] Chinese patent CN107805768A discloses a low-density aluminum-based composite material and its manufacturing method, which significantly improves strength through reasonable proportioning of raw materials and combination of components. However, the added raw materials are complex. Although the uniformity of distribution of each added raw material can be improved by mixing the slurry, the aluminum-based composite material is not sintered or subjected to subsequent hot processing. Therefore, the density of the aluminum-based composite material is still relatively high, and other mechanical properties are poor.

[0006] Chinese patent CN116732506A discloses a method for preparing a nickel-plated hollow silicon carbide microsphere reinforced aluminum matrix composite material. The method modifies the hollow material by plating nickel on its surface. However, ball milling may cause the nickel on the surface to peel off, affecting the performance of the composite material. In addition, the prepared composite material has a high density.

[0007] Chinese patent CN114231860A discloses a method for preparing a porous aluminum-based composite material reinforced by a mixture of nano-silicon carbide and hollow glass microspheres. This method does not modify the surface of the hollow glass microspheres, but instead adds nano-silicon carbide to the powder preform to prepare the composite material through subsequent liquid aluminum infiltration. Obviously, although the density of the prepared composite material is very low, the uniformity of the material's composition and properties is poor, making it unsuitable for large-scale industrial production and promotion.

[0008] Therefore, there is an urgent need to develop low-cost and efficient manufacturing technologies for high-performance, low-density, high-strength aluminum-based composite materials with a wide range of dimensional adjustments. Summary of the Invention

[0009] This invention addresses several technical problems in existing aluminum alloy composite materials, including poor wettability between hollow glass microspheres and the melt, low retention rate of the coating layer, difficulty in further improving casting performance, limitations on product size and shape, the use of numerous reinforcing components, complex and difficult operation, poor mechanical properties of the prepared composite material at low densities, difficulty in achieving the intended function of modified hollow glass microspheres after ball milling, poor uniformity of material composition and performance distribution, high preparation cost, low efficiency, poor and unstable product quality, and unfavorable conditions for large-scale industrial production and promotion. Therefore, this invention proposes a low-density, high-strength aluminum-based composite material and its preparation method that solves the aforementioned problems.

[0010] A low-density, high-strength aluminum-based composite material is composed of two parts: a matrix alloy and hollow glass microspheres. The hollow glass microspheres are added at an amount of 5-30 wt.%. The matrix alloy composition, by mass percentage, is: Cu 0-6.0 wt.%, Mg 0-3.0 wt.%, Zn 0-8.4 wt.%, with the balance being Al and unavoidable impurities. The hollow glass microsphere composition, by mass percentage, is: SiO2 70-80 wt.%, CaO 8-15 wt.%, Na2O 5-15 wt.%, B2O3 3-8 wt.%, Al2O3 2-3 wt.%.

[0011] Optionally, the microstructure of the low-density high-strength aluminum-based composite material consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes metastable phases such as Al2CuMg and MgZn2, which are uniformly distributed throughout the composite material, as the main reinforcing phases, as well as an α-Al phase.

[0012] Optionally, in the low-density high-strength aluminum-based composite material, the modified hollow glass microspheres still maintain a spherical shape with an average size of 5-40 μm and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0013] Optionally, the low-density, high-strength aluminum-based composite material has the following properties: density of 2.2-2.5 g / cm³. 3 The tensile strength is 300-550MPa, the yield strength is 200-420MPa, the yield ratio is 0.67-0.76, the elongation is 3-12%, and the strength-ductility product is 0.9-6.6GPa.

[0014] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0015] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres are coated by stirring in one or two colloidal solutions of silica sol and alumina sol, and then dried and crushed to obtain modified hollow glass microspheres. The coating thickness after drying is 0.2-1μm.

[0016] S2. Preparation of composite powder: First, aluminum alloy powder and modified hollow glass microspheres obtained in S1 are mixed evenly through a low-energy mixing process to obtain a mixed powder.

[0017] S3. Preparation of composite material green blank: The mixed powder obtained in S2 is loaded into a steel mold or soft sleeve, and aluminum-based green blank is obtained by steel mold pressing or cold isostatic pressing.

[0018] S4. Sintering densification: The aluminum-based green billet obtained in S3 is placed in the furnace of a sintering furnace for sintering densification to obtain a sintered ingot of the composite material.

[0019] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded or hot-rolled according to actual needs, and the deformed blank is heat-treated according to different application requirements.

[0020] Optionally, the stirring and coating time in S1 is 0.5-3h, the stirring speed is 50-200r / min, the drying temperature is 50-90℃, and the drying time is 2-8h.

[0021] Optionally, the aluminum alloy powder in S2 is prepared by an elemental mixing method, using nitrogen or air atomized aluminum powder with an average particle size of 2-50 μm, and the remainder being one or more of Mg, Cu, Zn elemental powders or Al-Mg, Al-Cu, and Al-Zn intermediate alloy powders; the aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 2-50 μm; the modified hollow glass microspheres have a hollow sphere structure with a wall thickness of 0.5-3 μm, and their composition is borosilicate; the modified hollow glass microspheres have an average particle size of 5-40 μm and a true density of 0.2-0.8 g / cm³. 3 .

[0022] Optionally, the element mixing method in S2 is one or more of the following: rolling ball milling, stirring ball milling, vibrating ball milling, and planetary ball milling, with a milling time of 6-18 hours and a ball-to-material ratio of 5:1-10:1.

[0023] Optionally, the S2 low-energy mixing process uses a V-type or three-dimensional mixer to uniformly mix the alloy powder with the modified hollow glass spheres for a mixing time of 4-24 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0024] Optionally, the soft sheath material in S3 is rubber or silicone, the cold isostatic pressing pressure is 100-200MPa, the holding time is 50-200s, and it is used to make complex shaped parts, bar blanks, tube blanks, plate blanks and irregular blanks.

[0025] Optionally, densification in S4 can be achieved through vacuum sintering or nitrogen sintering, with the vacuum degree of vacuum sintering reaching 10. -1 -10 -3 Pa, sintering temperature is 560-620℃, holding time is 1-6h.

[0026] Optionally, the hot extrusion or hot rolling temperature in S5 is 350-500℃, and the total deformation is 50-95%; the solution treatment temperature is 450-520℃, the solution treatment time is 1-5h, and the artificial aging temperature is 120-200℃ for 8-20h.

[0027] Technical principle of the invention:

[0028] This invention uses hollow glass microspheres as a reinforcing phase to prepare a low-density, high-strength aluminum-based composite material. The added glass microspheres are hollow spheres with a true density much lower than that of aluminum. The resulting composite material exhibits a significant reduction in density while maintaining high strength and plasticity. Due to issues such as poor wettability between the hollow glass microspheres and the matrix, and their tendency to break after reaction, this invention proposes modifying the hollow glass microspheres using silica sol or aluminum sol. The modified hollow glass microspheres retain their intact hollow spherical shape and exhibit stronger interfacial bonding with the matrix, maximizing their ability to significantly reduce the density of the composite material. Simultaneously, this enhances their resistance to compressive cracking and impact fracture, thus positively impacting the overall performance of the composite material.

[0029] The modified hollow glass microspheres of this invention exhibit high rigidity when the composite material is subjected to stress, allowing it to absorb more energy. At the same time, the strong bonding between the coating layer and the interface ensures the high strength of the material. The spherical shape of the hollow glass microspheres reduces the resistance during material processing and deformation, giving the composite material high plasticity. Furthermore, the extremely low true density of the hollow glass microspheres also gives the material a low-density characteristic.

[0030] The above technical solution has at least the following advantages compared with the existing technology:

[0031] The above-mentioned solution, proposed by this invention, provides a low-density, high-strength aluminum-based composite material and its preparation method. This addresses the technical problems existing in the prior art, such as poor wettability between hollow glass microspheres and the melt in traditional aluminum alloy composite materials, low retention rate of the coating layer, difficulty in further improving casting performance, limitations on product size and shape, the addition of numerous reinforcing components, complex and difficult operation, poor mechanical properties of the prepared composite material at low densities, difficulty in achieving the intended function of modified hollow glass microspheres after ball milling, poor uniformity of material composition and performance distribution, high preparation cost, low efficiency, poor and unstable finished product quality, and unfavorable conditions for large-scale industrial production and promotion.

[0032] The hollow glass microspheres used in this invention have a true density much lower than that of the aluminum matrix, which greatly reduces the density of the prepared aluminum-based composite material. The strong interfacial bonding between the modified hollow glass microspheres and the matrix, as well as the fine microstructure of the aluminum matrix grains, enable the composite material with the hollow structure to obtain high strength and high plasticity.

[0033] Compared with the stirring casting method for preparing hollow aluminum matrix composites, the technology of this invention improves the phenomena of alloy composition segregation, uneven distribution of the second phase and poor interfacial wettability, and avoids the generation of casting defects such as porosity and looseness. Compared with the hot pressing sintering method for preparing aluminum matrix composites, it can realize the efficient manufacturing of large-size aluminum matrix composite products and broaden the application range of products.

[0034] The invention of hollow glass microsphere reinforced aluminum matrix composite material prepared by powder metallurgy pressureless sintering combined with hot deformation processing has unique advantages. Pressureless sintering can improve the blanking efficiency and significantly reduce the blanking cost. The use of ultrafine hollow glass microspheres can prevent the hollow structure from being damaged during blanking and hot deformation processing. It has strong process adaptability, a wide plastic processing window, and a high yield, and can realize large-scale industrial production.

[0035] The technology of this invention enables the low-cost preparation and processing of low-density, high-strength aluminum-based composite materials. The process is simple, the production efficiency is high, and it is suitable for large-scale industrial production. It has great application prospects in aerospace, new energy vehicles, shipbuilding, electronic communications and other fields.

[0036] This invention improves the resistance to compression cracking and impact fracture of hollow glass microspheres by modifying their surface; it ensures that the modified hollow glass microspheres are completely and uniformly distributed in the aluminum alloy matrix through low-energy mixing and pressureless sintering densification processes; and it endows the composite material with excellent mechanical properties through a synergistic process of extrusion and heat treatment.

[0037] This invention utilizes aging treatment to induce precipitation of alloy components in the matrix, resulting in precipitation strengthening. Controlling the aging temperature and time allows for the control of phase precipitation. By maintaining the temperature and time within appropriate ranges, a large quantity and uniformity of metastable phases are precipitated, and these phases are retained at room temperature. The presence of these metastable phases enables the material to reach peak strength at room temperature. Furthermore, by adjusting the aging temperature, the degree and size of the precipitated phases can be controlled, thereby achieving regulation of the overall properties of the composite material.

[0038] This invention uses a V-shaped or three-dimensional mixer to mix modified hollow glass microspheres with alloy powder, avoiding the problem of surface coating detachment after rolling mixing in existing technologies, which affects subsequent material properties. The hollow glass microspheres and alloy powder are mixed uniformly, maintaining their complete spherical shape, and the coating layer is well bonded to the hollow glass microspheres and alloy matrix, making it less prone to detachment.

[0039] In summary, compared with traditional methods for preparing aluminum alloy composite materials, the method of this invention can obtain composite materials through surface modification of hollow glass microspheres, preparation of composite powder, preparation of composite green body, sintering densification, deformation processing, and heat treatment. This method has a short preparation process, simple operation, low preparation cost, and high efficiency. The modified hollow microspheres are not only uniformly distributed, but also retain their complete spherical shape after mixing. The modified coating layer has a high degree of retention and good bonding with the matrix, resulting in good microstructure uniformity. This achieves low density, high strength, and high yield of composite materials, which is conducive to large-scale industrial production and promotion. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a SEM microstructure image of a low-density, high-strength aluminum-based composite material according to Example 1 of the present invention;

[0042] Figure 2 This is an EDS elemental distribution diagram of a low-density, high-strength aluminum-based composite material according to Embodiment 1 of the present invention;

[0043] Figure 3 This is a tensile fracture morphology diagram of a low-density, high-strength aluminum-based composite material according to Embodiment 1 of the present invention. Detailed Implementation

[0044] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0045] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0046] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0047] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0048] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0049] A low-density, high-strength aluminum-based composite material is composed of two parts: a matrix alloy and hollow glass microspheres. The hollow glass microspheres are added at an amount of 5-30 wt.%. The matrix alloy composition, by mass percentage, is: Cu 0-6.0 wt.%, Mg 0-3.0 wt.%, Zn 0-8.4 wt.%, with the balance being Al and unavoidable impurities. The hollow glass microsphere composition, by mass percentage, is: SiO2 70-80 wt.%, CaO 8-15 wt.%, Na2O 5-15 wt.%, B2O3 3-8 wt.%, Al2O3 2-3 wt.%.

[0050] Specifically, the microstructure of the low-density high-strength aluminum-based composite material consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes metastable phases such as Al2CuMg and MgZn2, which are uniformly distributed throughout the composite material, as the main reinforcing phases, as well as an α-Al phase.

[0051] In particular, in the low-density high-strength aluminum-based composite material, the modified hollow glass microspheres still maintain a spherical shape with an average size of 5-40 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0052] Specifically, the low-density, high-strength aluminum-based composite material has the following properties: density of 2.2-2.5 g / cm³. 3 The tensile strength is 300-550MPa, the yield strength is 200-420MPa, the yield ratio is 0.67-0.76, the elongation is 3-12%, and the strength-ductility product is 0.9-6.6GPa.

[0053] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0054] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres are coated by stirring in one or two colloidal solutions of silica sol and alumina sol, and then dried and crushed to obtain modified hollow glass microspheres. The coating thickness after drying is 0.2-1μm.

[0055] S2. Preparation of composite powder: First, aluminum alloy powder and modified hollow glass microspheres obtained in S1 are mixed evenly through a low-energy mixing process to obtain a mixed powder.

[0056] S3. Preparation of composite material green blank: The mixed powder obtained in S2 is loaded into a steel mold or soft sleeve, and aluminum-based green blank is obtained by steel mold pressing or cold isostatic pressing.

[0057] S4. Sintering densification: The aluminum-based green billet obtained in S3 is placed in the furnace of a sintering furnace for sintering densification to obtain a sintered ingot of the composite material.

[0058] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded or hot-rolled according to actual needs, and the deformed blank is heat-treated according to different application requirements.

[0059] Specifically, in S1, the stirring and coating time is 0.5-3h, the stirring speed is 50-200r / min, the drying temperature is 50-90℃, and the drying time is 2-8h.

[0060] Specifically, the aluminum alloy powder in S2 is prepared by an elemental mixing method, using nitrogen or air-atomized aluminum powder with an average particle size of 2-50 μm, and the remainder being one or more of the following: elemental powders of Mg, Cu, Zn, and Si, or intermediate alloy powders of Al-Mg, Al-Cu, Al-Zn, and Al-Si; the aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 2-50 μm; the modified hollow glass microspheres have a hollow sphere structure with a wall thickness of 0.5-3 μm, and their composition is borosilicate; the modified hollow glass microspheres have an average particle size of 5-40 μm and a true density of 0.2-0.8 g / cm³. 3 .

[0061] Specifically, the element mixing method in S2 is carried out by one or more of the following: rolling ball milling, stirring ball milling, vibrating ball milling, and planetary ball milling, with a milling time of 6-18 hours and a ball-to-material ratio of 5:1-10:1.

[0062] In particular, the S2 low-energy mixing process uses a V-type or three-dimensional mixer to uniformly mix the alloy powder with the modified hollow glass spheres for a mixing time of 4-24 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0063] Specifically, the soft sheath material in S3 is rubber or silicone, the cold isostatic pressing pressure is 100-200MPa, and the holding time is 50-200s. It is used to make complex shaped parts, bar blanks, tube blanks, plate blanks and irregular blanks.

[0064] Specifically, densification in S4 is achieved through vacuum sintering or nitrogen sintering, with the vacuum degree of vacuum sintering reaching 10. -1 -10 -3 Pa, sintering temperature is 560-620℃, holding time is 1-6h.

[0065] Specifically, in S5, the hot extrusion or hot rolling temperature is 350-500℃, and the total deformation is 50-95%; the solution treatment temperature is 450-520℃, the solution treatment time is 1-5h, and the artificial aging temperature is 120-200℃ for 8-20h.

[0066] Example 1

[0067] A low-density, high-strength aluminum-based composite material, wherein the aluminum alloy powder of the low-density, high-strength aluminum-based composite material is prepared according to the element content of 2024 aluminum alloy, and the composition by mass percentage is: Cu 4.9wt.%, Mg 1.8wt.%, with the balance being Al and unavoidable impurities.

[0068] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0069] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres are stirred and coated in silica sol for 0.5-3 hours. The stirring and coating time is 0.5 hours and the stirring speed is 200 r / min. Modified hollow glass microspheres are obtained by drying and crushing. The drying temperature is 90℃ and the drying time is 2 hours. The coating thickness after drying is 0.2 μm.

[0070] S2. Preparation of Composite Powder: Aluminum alloy powder and the modified hollow glass microspheres obtained in S1 are first mixed uniformly using a low-energy mixing process to obtain a mixed powder. The aluminum alloy powder is prepared by an elemental mixing method, using aluminum powder with an average particle size of 20 μm. The remainder consists of Mg and Cu elemental powders. The aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 20 μm. The hollow glass microspheres have a hollow sphere structure, an average particle size of 5 μm, and a true density of 0.8 g / cm³. 3 Its composition is borosilicate; the modified hollow glass microspheres have a wall thickness of 0.7 μm and an addition amount of 30 wt.%.

[0071] The element mixing method involves mixing via planetary ball milling for 6 hours at a ball-to-material ratio of 10:1.

[0072] The low-energy mixing process uses a V-type mixer to uniformly mix alloy powder with modified hollow glass spheres for 12 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0073] S3. Preparation of composite material green body: The mixed powder obtained in S2 is loaded into a rubber sleeve and cold isostatically pressed to obtain an aluminum-based green body; the cold isostatic pressing pressure is 100MPa and the holding time is 200s.

[0074] S4. Sintering densification: The aluminum-based green billet obtained in S3 is placed in the furnace of a sintering furnace for sintering densification. The sintering densification is carried out by nitrogen sintering at a temperature of 620℃ and a holding time of 1h to obtain a sintered ingot of the composite material.

[0075] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded at 390°C according to actual needs, with an extrusion ratio of 16:1; the deformed blank is heat-treated according to different usage requirements. In this embodiment, the extruded bar is subjected to T6 heat treatment, solution treatment at 520°C, followed by water quenching, and then artificial aging at 180°C for 10 hours.

[0076] like Figure 2 As shown, the microstructure of the low-density, high-strength aluminum-based composite material prepared in this embodiment consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes the main reinforcing phase Al2CuMg phase, which is uniformly distributed throughout the composite material, as well as the α-Al phase.

[0077] like Figure 1 and 3 As shown, in the low-density high-strength aluminum-based composite material prepared in this embodiment, the modified hollow glass microspheres still maintain a spherical shape with an average size of 5 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0078] The low-density, high-strength aluminum-based composite material prepared in this embodiment has the following properties: density of 2.5 g / cm³. 3 It has a tensile strength of 365 MPa, a yield strength of 246 MPa, a yield-to-tensile ratio of 0.674, an elongation of 4.8%, and a strength-ductility product of 1.75 GPa.

[0079] Example 2

[0080] A low-density, high-strength aluminum-based composite material, wherein the aluminum alloy powder of the low-density, high-strength aluminum-based composite material is prepared according to the element content of 2024 aluminum alloy, and the composition by mass percentage is: Cu 4.9wt.%, Mg 1.8wt.%, with the balance being Al and unavoidable impurities.

[0081] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0082] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres were stirred and coated in silica sol for 0.5 h at a stirring speed of 180 r / min. Modified hollow glass microspheres were obtained by drying and crushing at a temperature of 90 ℃ for 2 h. The coating thickness after drying was 0.3 μm.

[0083] S2. Preparation of Composite Powder: Aluminum alloy powder and the modified hollow glass microspheres obtained in S1 are first mixed uniformly using a low-energy mixing process to obtain a mixed powder. The aluminum alloy powder is prepared by an elemental mixing method, using aluminum powder with an average particle size of 2 μm, while the remainder consists of Mg and Cu elemental powders. The aluminum alloy powder is also prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 2 μm. The hollow glass microspheres have a hollow sphere structure, an average particle size of 10 μm, and a true density of 0.6 g / cm³. 3 Its composition is borosilicate; the modified hollow glass microspheres have a wall thickness of 1 μm and an addition amount of 20 wt.%.

[0084] The element mixing method involves stirring and ball milling for 18 hours, with a ball-to-material ratio of 5:1.

[0085] The low-energy mixing process uses a V-type mixer to uniformly mix alloy powder with modified hollow glass spheres for 20 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0086] S3. Preparation of composite material green body: The mixed powder obtained in S2 is loaded into a rubber sleeve and cold isostatically pressed to obtain an aluminum-based green body; the cold isostatic pressing pressure is 200MPa and the holding time is 90s;

[0087] S4. Sintering and Densification: The aluminum-based green billet obtained in S3 is placed in a nitrogen atmosphere furnace for sintering and densification. The sintering and densification is performed under vacuum, with a vacuum degree of 10. -3 Pa, sintering temperature is 600℃, holding time is 2h, and sintered ingot of composite material is obtained;

[0088] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded at 400℃ according to actual needs, with an extrusion ratio of 16:1; the deformed blank is heat-treated according to different usage requirements. In this embodiment, the extruded bar is subjected to T6 heat treatment, solution treatment at 505℃, followed by water quenching, and then artificial aging at 185℃ for 12 hours.

[0089] The microstructure of the low-density, high-strength aluminum-based composite material prepared in this embodiment consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes the main reinforcing phase Al2CuMg phase, which is uniformly distributed throughout the composite material, as well as the α-Al phase.

[0090] In the low-density, high-strength aluminum-based composite material prepared in this embodiment, the modified hollow glass microspheres still maintain a spherical shape with an average size of 10 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0091] The low-density, high-strength aluminum-based composite material prepared in this embodiment has the following properties: density of 2.3 g / cm³.3 The tensile strength is 421 MPa, the yield strength is 282 MPa, the yield ratio is 0.670, the elongation is 12%, and the strength-ductility product is 5.05 GPa.

[0092] Example 3

[0093] A low-density, high-strength aluminum-based composite material, wherein the aluminum alloy powder of the low-density, high-strength aluminum-based composite material is prepared into 7075 aluminum alloy powder by nitrogen atomization according to the element content of 7055 aluminum alloy. The composition by mass percentage is: Cu 2.6wt.%, Mg 2.3wt.%, Zn 8.3wt.%, with the balance being Al and unavoidable impurities.

[0094] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0095] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres were stirred and coated in aluminum sol for 2 hours at a stirring speed of 120 r / min. Modified hollow glass microspheres were obtained by drying and crushing at a temperature of 80℃ for 4 hours. The coating thickness after drying was 0.8 μm.

[0096] S2. Preparation of Composite Powder: Aluminum alloy powder and the modified hollow glass microspheres obtained in S1 are first mixed uniformly using a low-energy mixing process to obtain a mixed powder. The aluminum alloy powder is prepared by an elemental mixing method, using aluminum powder with an average particle size of 50 μm. The remainder consists of one or more of the following: elemental powders of Mg, Cu, and Zn, or intermediate alloy powders of Al-Mg, Al-Cu, and Al-Zn. The aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 50 μm. The hollow glass microspheres have a hollow sphere structure, an average particle size of 40 μm, and a true density of 0.2 g / cm³. 3 Its composition is borosilicate; the modified hollow glass microspheres have a wall thickness of 3.8 μm and an addition amount of 30 wt.%.

[0097] The element mixing method involves planetary ball milling for 12 hours with a ball-to-material ratio of 5:1.

[0098] The low-energy mixing process uses a V-type mixer to uniformly mix alloy powder with modified hollow glass spheres for 24 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0099] S3. Preparation of composite material green body: The mixed powder obtained in S2 is loaded into a rubber sleeve and cold isostatically pressed to obtain an aluminum-based green body; the cold isostatic pressing pressure is 150MPa and the holding time is 120s.

[0100] S4. Sintering and Densification: The aluminum-based green billet obtained in S3 is placed in a vacuum furnace for sintering and densification. Sintering and densification is performed under vacuum, with a vacuum degree of 10. -2 Pa, sintering temperature is 560℃, holding time is 6h, and sintered ingot of composite material is obtained;

[0101] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded at 450°C according to actual needs, with an extrusion ratio of 36:1; the deformed blank is heat-treated according to different usage requirements. In this embodiment, the extruded bar is subjected to T6 heat treatment, solution treatment at 475°C, followed by water quenching, and then artificial aging at 120°C for 24 hours.

[0102] The microstructure of the low-density, high-strength aluminum-based composite material prepared in this embodiment consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes the main reinforcing phase MgZn2 phase, which is uniformly distributed throughout the composite material, as well as the α-Al phase.

[0103] In the low-density, high-strength aluminum-based composite material prepared in this embodiment, the modified hollow glass microspheres still maintain a spherical shape with an average size of 40 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0104] The low-density, high-strength aluminum-based composite material prepared in this embodiment has the following properties: density of 2.2 g / cm³. 3 The tensile strength is 508 MPa, the yield strength is 386 MPa, the yield ratio is 0.760, the elongation is 3%, and the strength-ductility product is 1.52 GPa.

[0105] Example 4

[0106] A low-density, high-strength aluminum-based composite material, wherein the aluminum alloy powder of the low-density, high-strength aluminum-based composite material is prepared by nitrogen atomization according to the element content of 7055 aluminum alloy, and the composition by mass percentage is: Cu 2.6wt.%, Mg 2.3wt.%, Zn 8.3wt.%, with the balance being Al and unavoidable impurities.

[0107] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0108] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres were stirred and coated in aluminum sol for 1 hour at a stirring speed of 200 r / min to coat the surface with nano-alumina. Modified hollow glass microspheres were obtained by drying and crushing at a temperature of 60℃ for 8 hours. The coating thickness after drying was 0.4 μm.

[0109] S2. Preparation of Composite Powder: Aluminum alloy powder and the modified hollow glass microspheres obtained in S1 are first mixed uniformly using a low-energy mixing process to obtain a mixed powder. The aluminum alloy powder is prepared by an elemental mixing method, using aluminum powder with an average particle size of 10 μm. The remainder consists of one or more of the following: elemental powders of Mg, Cu, and Zn, or intermediate alloy powders of Al-Mg, Al-Cu, and Al-Zn. The aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 10 μm. The hollow glass microspheres have a hollow sphere structure, an average particle size of 10 μm, and a true density of 0.6 g / cm³. 3 Its composition is borosilicate; the modified hollow glass microspheres have a wall thickness of 1.1 μm and the addition amount of modified hollow glass microspheres is 5 wt.%.

[0110] The element mixing method involves vibratory ball milling for 10 hours, with a ball-to-material ratio of 8:1.

[0111] The low-energy mixing process uses a three-dimensional mixer to uniformly mix alloy powder with modified hollow glass spheres for 4 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0112] S3. Preparation of composite material green blank: The mixed powder obtained in S2 is loaded into a rubber sleeve and cold isostatically pressed to obtain an aluminum-based green blank; the cold isostatic pressing pressure is 150MPa and the holding time is 150s.

[0113] S4. Sintering and Densification: The aluminum-based green billet obtained in S3 is placed in a vacuum furnace for sintering and densification. Sintering and densification is performed under vacuum, with a vacuum degree of 10. -3 Pa, sintering temperature is 580℃, holding time is 1h, and sintered ingot of composite material is obtained;

[0114] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded at 400℃ according to actual needs, with an extrusion ratio of 25:1; the deformed blank is heat-treated according to different usage requirements. In this embodiment, the extruded bar is subjected to T6 heat treatment, solution treatment at 480℃, followed by water quenching, and then artificial aging at 120℃ for 24 hours.

[0115] The microstructure of the low-density, high-strength aluminum-based composite material prepared in this embodiment consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes the main reinforcing phase MgZn2 phase, which is uniformly distributed throughout the composite material, as well as the α-Al phase.

[0116] In the low-density, high-strength aluminum-based composite material prepared in this embodiment, the modified hollow glass microspheres still maintain a spherical shape with an average size of 10 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0117] The low-density, high-strength aluminum-based composite material prepared in this embodiment has the following properties: density of 2.46 g / cm³. 3 The tensile strength is 531 MPa, the yield strength is 402 MPa, the yield ratio is 0.75, the elongation is 4.8%, and the strength-ductility product is 2.55 GPa.

[0118] Example 5

[0119] A low-density, high-strength aluminum-based composite material, wherein the aluminum alloy powder of the low-density, high-strength aluminum-based composite material is prepared by nitrogen atomization according to the element content of 7055 aluminum alloy, and the composition by mass percentage is: Cu 2.6wt.%, Mg 2.3wt.%, Zn 8.3wt.%, with the balance being Al and unavoidable impurities.

[0120] A method for preparing the low-density, high-strength aluminum-based composite material, comprising the following steps:

[0121] S1. Surface modification of hollow glass microspheres: Hollow glass microspheres were stirred and coated in aluminum sol for 0.5 h at a stirring speed of 200 r / min to coat the surface with nano-alumina. Modified hollow glass microspheres were obtained by drying and crushing at 80 ℃ for 4 h. The coating thickness after drying was 0.3 μm.

[0122] S2. Preparation of Composite Powder: Aluminum alloy powder and the modified hollow glass microspheres obtained in S1 are first mixed uniformly using a low-energy mixing process to obtain a mixed powder. The aluminum alloy powder is prepared by an elemental mixing method, using aluminum powder with an average particle size of 10 μm. The remainder consists of one or more of the following: elemental powders of Mg, Cu, and Zn, or intermediate alloy powders of Al-Mg, Al-Cu, and Al-Zn. The aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 10 μm. The hollow glass microspheres have a hollow sphere structure, an average particle size of 5 μm, and a true density of 0.8 g / cm³. 3 Its composition is borosilicate; the modified hollow glass microspheres have a wall thickness of 0.8 μm and an addition amount of 20 wt.%.

[0123] The element mixing method involves vibratory ball milling for 10 hours, with a ball-to-material ratio of 8:1.

[0124] The low-energy mixing process uses a three-dimensional mixer to uniformly mix alloy powder with modified hollow glass spheres for 4 hours to ensure the integrity of the surface morphology of the modified hollow glass spheres.

[0125] S3. Preparation of composite material green blank: The mixed powder obtained in S2 is loaded into a rubber sleeve and cold isostatically pressed to obtain an aluminum-based green blank; the cold isostatic pressing pressure is 150MPa and the holding time is 150s.

[0126] S4. Sintering and densification: The aluminum-based green billet obtained in S3 is placed in a vacuum furnace for sintering and densification. The sintering and densification is vacuum sintering. The vacuum degree of vacuum sintering reaches 10-3 Pa, the sintering temperature is 560℃, and the holding time is 1h to obtain the sintered ingot of the composite material.

[0127] S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded at 420℃ according to actual needs, with an extrusion ratio of 25:1; the deformed blank is heat-treated according to different usage requirements. In this embodiment, the extruded bar is subjected to T6 heat treatment, solution treatment at 470℃, followed by water quenching, and then artificial aging at 120℃ for 24 hours.

[0128] The microstructure of the low-density, high-strength aluminum-based composite material prepared in this embodiment consists of 10% hollow glass microspheres by volume; the remainder is a matrix alloy phase, including the main reinforcing phase MgZn2 phase uniformly distributed throughout the composite material, and the α-Al phase.

[0129] In the low-density, high-strength aluminum-based composite material prepared in this embodiment, the modified hollow glass microspheres still maintain a spherical shape with an average size of 5 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

[0130] The low-density, high-strength aluminum-based composite material prepared in this embodiment has the following properties: density of 2.38 g / cm³. 3 It has a tensile strength of 550 MPa, a yield strength of 416 MPa, a yield-to-tensile ratio of 0.75, an elongation of 4.4%, and a strength-ductility product of 2.42 GPa.

[0131] Comparative Example 1

[0132] For Example 1, the amount of hollow glass microspheres added in S2 was changed to 40 wt.%, and the other steps were the same as in Example 1.

[0133] Performance testing showed a density of 2.42 g / cm³. 3 The tensile strength is 230 MPa, the yield strength is 164 MPa, the yield-to-tensile ratio is 0.71, the elongation is 1.7%, and the strength-ductility product is 0.39 GPa%. Compared with Example 1, it is shown that excessive addition of modified hollow glass microspheres affects the material forming and sintering process, drastically reduces the strength and plasticity of the extruded bar, and seriously affects the performance of the composite material.

[0134] Comparative Example 2

[0135] For Example 2, the stirring time and speed in S1 were changed to 8h and 50r / min, respectively, and the thickness of the coating layer after drying was 1μm. The remaining steps were the same as in Example 2.

[0136] Performance testing showed a density of 2.48 g / cm³. 3 The tensile strength is 260 MPa, the yield strength is 186 MPa, the yield-to-tensile ratio is 0.71, the elongation is 8.2%, and the strength-ductility product is 2.13 GPa%. Comparative Example 2 shows that when modifying hollow glass microspheres, prolonged stirring time and excessively slow stirring speed can lead to an excessively thick coating layer, which will affect the densification process of the material and reduce the material properties.

[0137] Comparative Example 3

[0138] For Examples 3 and 4, the hot extrusion temperature in S6 is 520°C, the extrusion ratio is 25:1, and the other steps are the same as in Examples 3 and 4.

[0139] The obtained sample surface showed obvious fish-scale cracks. Performance tests were conducted on samples taken from intact areas of the sample, and the density was 2.5 g / cm³. 3 The tensile strength was 402 MPa, the yield strength was 264 MPa, the yield-to-tensile ratio was 0.65, the elongation was 3.6%, and the strength-ductility product was 1.44 GPa%. Compared with Examples 3 and 4, the extrusion temperature was too high, the surface temperature of the 7055 aluminum-based composite material was too high, the deformation resistance decreased drastically, and the surface of the composite material tore under the action of extrusion friction, resulting in serious deterioration of mechanical properties.

[0140] Comparative Example 4

[0141] In Example 5, the hollow glass microspheres are not surface modified in S1, and the remaining steps are the same as in Example 5.

[0142] Performance testing showed a density of 2.49 g / cm³. 3 The tensile strength was 493 MPa, the yield strength was 371 MPa, the yield ratio was 0.75, the elongation was 3.7%, and the strength-ductility product was 1.85 GPa%. Compared to Example 5, the density increased because the modified coating layer was lost. Some hollow glass microspheres were directly broken during the composite material preparation process, or SiO2 reacted with matrix alloying elements such as Mg, indirectly causing their breakage. Subsequently, the matrix alloy filled the cavities, rendering the density-reducing effect of these hollow glass microspheres ineffective. In Comparative Example 5, the tensile and yield strengths decreased by 10.4% and 10.8%, respectively. This was due to the poor wettability between the unmodified hollow glass microspheres and the matrix interface, resulting in decreased load-bearing capacity and reduced plasticity after breakage. This indicates that modifying hollow glass microspheres can significantly improve the overall performance of the composite material.

[0143] The above-mentioned solution, proposed by this invention, provides a low-density, high-strength aluminum-based composite material and its preparation method. This addresses the technical problems existing in the prior art, such as poor wettability between hollow glass microspheres and the melt in traditional aluminum alloy composite materials, low retention rate of the coating layer, difficulty in further improving casting performance, limitations on product size and shape, the addition of numerous reinforcing components, complex and difficult operation, poor mechanical properties of the prepared composite material at low densities, difficulty in achieving the intended function of modified hollow glass microspheres after ball milling, poor uniformity of material composition and performance distribution, high preparation cost, low efficiency, poor and unstable finished product quality, and unfavorable conditions for large-scale industrial production and promotion.

[0144] The hollow glass microspheres used in this invention have a true density much lower than that of the aluminum matrix, which greatly reduces the density of the prepared aluminum-based composite material. The strong interfacial bonding between the modified hollow glass microspheres and the matrix, as well as the fine microstructure of the aluminum matrix grains, enable the composite material with the hollow structure to obtain high strength and high plasticity.

[0145] Compared with the stirring casting method for preparing hollow aluminum matrix composites, the technology of this invention improves the phenomena of alloy composition segregation, uneven distribution of the second phase and poor interfacial wettability, and avoids the generation of casting defects such as porosity and looseness. Compared with the hot pressing sintering method for preparing aluminum matrix composites, it can realize the efficient manufacturing of large-size aluminum matrix composite products and broaden the application range of products.

[0146] The invention of hollow glass microsphere reinforced aluminum matrix composite material prepared by powder metallurgy pressureless sintering combined with hot deformation processing has unique advantages. Pressureless sintering can improve the blanking efficiency and significantly reduce the blanking cost. The use of ultrafine hollow glass microspheres can prevent the hollow structure from being damaged during blanking and hot deformation processing. It has strong process adaptability, a wide plastic processing window, and a high yield, and can realize large-scale industrial production.

[0147] The technology of this invention enables the low-cost preparation and processing of low-density, high-strength aluminum-based composite materials. The process is simple, the production efficiency is high, and it is suitable for large-scale industrial production. It has great application prospects in aerospace, new energy vehicles, shipbuilding, electronic communications and other fields.

[0148] This invention improves the resistance to compression cracking and impact fracture of hollow glass microspheres by modifying their surface; it ensures that the modified hollow glass microspheres are completely and uniformly distributed in the aluminum alloy matrix through low-energy mixing and pressureless sintering densification processes; and it endows the composite material with excellent mechanical properties through a synergistic process of extrusion and heat treatment.

[0149] This invention utilizes aging treatment to induce precipitation of alloy components in the matrix, resulting in precipitation strengthening. Controlling the aging temperature and time allows for the control of phase precipitation. By maintaining the temperature and time within appropriate ranges, a large quantity and uniformity of metastable phases are precipitated, and these phases are retained at room temperature. The presence of these metastable phases enables the material to reach peak strength at room temperature. Furthermore, by adjusting the aging temperature, the degree and size of the precipitated phases can be controlled, thereby achieving regulation of the overall properties of the composite material.

[0150] This invention uses a V-shaped or three-dimensional mixer to mix modified hollow glass microspheres with alloy powder, avoiding the problem of surface coating detachment after rolling mixing in existing technologies, which affects subsequent material properties. The hollow glass microspheres and alloy powder are mixed uniformly, maintaining their complete spherical shape, and the coating layer is well bonded to the hollow glass microspheres and alloy matrix, making it less prone to detachment.

[0151] In summary, compared with traditional methods for preparing aluminum alloy composite materials, the method of this invention can obtain composite materials through surface modification of hollow glass microspheres, preparation of composite powder, preparation of composite green body, sintering densification, deformation processing, and heat treatment. This method has a short preparation process, simple operation, low preparation cost, and high efficiency. The modified hollow microspheres are not only uniformly distributed, but also retain their complete spherical shape after mixing. The modified coating layer has a high degree of retention and good bonding with the matrix, resulting in good microstructure uniformity. This achieves low density, high strength, and high yield of composite materials, which is conducive to large-scale industrial production and promotion.

[0152] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0153] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0154] It should be understood that, in various embodiments of the present invention, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0155] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-density, high-strength aluminum-based composite material, characterized in that, The low-density, high-strength aluminum-based composite material consists of two parts: a matrix alloy and hollow glass microspheres, wherein the hollow glass microspheres are added at a rate of 5-30 wt.%; the matrix alloy composition, by mass percentage, is: Cu 0-6.0 wt.%, Mg 0-3.0 wt.%, Zn 0-8.4 wt.%, with the balance being Al and unavoidable impurities; the hollow glass microsphere composition, by mass percentage, is: SiO2 70-80 wt.%, CaO 8-15 wt.%, Na2O 5-15 wt.%, B2O3 3-8 wt.%, Al2O3 2-3 wt.%.

2. The low-density, high-strength aluminum-based composite material according to claim 1, characterized in that, The microstructure of the low-density, high-strength aluminum-based composite material consists of hollow glass microspheres and a matrix alloy phase. The matrix alloy phase includes metastable phases such as Al2CuMg and MgZn2, which are uniformly distributed throughout the composite material as the main reinforcing phases, as well as an α-Al phase.

3. The low-density, high-strength aluminum-based composite material according to claim 1, characterized in that, In the aforementioned low-density, high-strength aluminum-based composite material, the modified hollow glass microspheres retain their spherical shape, with an average size of 5-40 μm, and are uniformly dispersed in the matrix phase, i.e., the α-Al phase.

4. The low-density, high-strength aluminum-based composite material according to claim 1, characterized in that, The properties of the aforementioned low-density, high-strength aluminum-based composite material are: density of 2.2-2.5 g / cm³. 3 The tensile strength is 300-550MPa, the yield strength is 200-420MPa, the yield ratio is 0.67-0.76, the elongation is 3-12%, and the strength-ductility product is 0.9-6.6GPa.

5. A method for preparing a low-density, high-strength aluminum-based composite material according to claim 1, characterized in that, The preparation method of the low-density, high-strength aluminum-based composite material includes the following steps: S1. Surface modification of hollow glass microspheres: Hollow glass microspheres are coated by stirring in one or two colloidal solutions of silica sol and alumina sol, and then dried and crushed to obtain modified hollow glass microspheres. The coating thickness after drying is 0.2-1μm. S2. Preparation of composite powder: First, aluminum alloy powder and modified hollow glass microspheres obtained in S1 are mixed evenly through a low-energy mixing process to obtain a mixed powder. S3. Preparation of composite material green blank: The mixed powder obtained in S2 is loaded into a steel mold or soft sleeve, and aluminum-based green blank is obtained by steel mold pressing or cold isostatic pressing. S4. Sintering densification: The aluminum-based green billet obtained in S3 is placed in the furnace of a sintering furnace for sintering densification to obtain a sintered ingot of the composite material. S5. Deformation and heat treatment: The sintered ingot of the composite material obtained in S4 is hot-extruded or hot-rolled according to actual needs, and the deformed blank is heat-treated according to different application requirements.

6. The method for preparing low-density, high-strength aluminum-based composite material according to claim 5, characterized in that, In S1, the stirring and coating time is 0.5-3h, the stirring speed is 50-200r / min, the drying temperature is 50-90℃, and the drying time is 2-8h.

7. The method for preparing low-density, high-strength aluminum-based composite material according to claim 5, characterized in that, The aluminum alloy powder in S2 is prepared by an elemental mixing method, using nitrogen or air atomized aluminum powder with an average particle size of 2-50 μm. The remainder consists of one or more of the following: elemental powders of Mg, Cu, and Zn, or intermediate alloy powders of Al-Mg, Al-Cu, and Al-Zn. The aluminum alloy powder is prepared by nitrogen atomization, using aluminum alloy powder with an average particle size of 2-50 μm. The modified hollow glass microspheres have a hollow sphere structure with a wall thickness of 0.5-3 μm and are composed of borosilicate. The modified hollow glass microspheres have an average particle size of 5-40 μm and a true density of 0.2-0.8 g / cm³. 3 .

8. The method for preparing low-density, high-strength aluminum-based composite material according to claim 5, characterized in that, The soft sheath material in S3 is rubber or silicone. The cold isostatic pressing pressure is 100-200MPa, and the holding time is 50-200s. It is used to make complex shaped parts, bar blanks, tube blanks, plate blanks, and irregular blanks.

9. The method for preparing low-density, high-strength aluminum-based composite material according to claim 5, characterized in that, In S4, densification is achieved through vacuum sintering or nitrogen sintering, with the vacuum degree of vacuum sintering reaching 10. -1 -10 -3 Pa, sintering temperature is 560-620℃, holding time is 1-6h.

10. The method for preparing the low-density, high-strength aluminum-based composite material according to claim 5, characterized in that, The hot extrusion or hot rolling temperature of S5 is 350-500℃, and the total deformation is 50-95%; the solution treatment temperature is 450-520℃, the solution treatment time is 1-5h, and the artificial aging temperature is 120-200℃ for 8-20h.

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