Aluminum-based composite material with gradient structure surface strengthening layer and preparation method of aluminum-based composite material

Abstract

The invention discloses an aluminum-based composite material with a gradient structure surface strengthening layer and a preparation method of the aluminum-based composite material. The aluminum-based composite material with the gradient structure surface strengthening layer comprises a composite material body and the gradient structure surface strengthening layer, wherein the composite material body is formed by a reinforcing body and a base body, and the gradient structure surface strengthening layer is generated on the surface of the composite material body in situ; wherein the reinforcement is carbide, and the matrix is pure aluminum or aluminum alloy; the gradient structure surface strengthening layer comprises an aluminum nitride and / or aluminum carbide strengthening layer, a nitrogen and / or carbon diffusion layer and a transition layer located between the aluminum nitride and / or aluminum carbide strengthening layer and the nitrogen and / or carbon diffusion layer. The carbide particles are introduced to serve as a reinforcing body, so that the overall hardness of the aluminum-based composite material is improved; the gradient structure surface strengthening layer is constructed on the surface of the composite material body in situ, so that the residual stress between the coating and the composite material body is obviously relieved, the bonding property of the coating and the composite material body is improved, and falling is prevented; and meanwhile, the gradient structure surface strengthening layer can further improve the hardness and wear resistance of the surface of the aluminum-based composite material.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to an aluminum-based composite material with a gradient structure surface reinforcement layer and its preparation method. Background Technology

[0002] Currently, carbide ceramic particles have attracted widespread attention in the automotive, energy, and aerospace industries due to their low density, high strength, and high hardness. Carbide ceramic particle-reinforced aluminum matrix composites, prepared by combining them with aluminum matrix composites, are mainly used in engine piston parts, aerospace components, and bulletproof vests. However, the surface hardness of current carbide ceramic particle-reinforced aluminum matrix composites is relatively low, only 100-300 HV, resulting in poor resistance to friction and wear, making it difficult to meet the requirements of high-strength applications.

[0003] Existing technologies typically involve depositing hard coatings on the surface of composite materials to improve the wear resistance of aluminum-based composites. However, a distinct interface exists between the hard coating and the composite material, resulting in insufficient bonding strength. Furthermore, the significant difference in the coefficients of thermal expansion between Al and the hard coating leads to high residual stress at the film-substrate interface, causing failure behaviors such as cracking and peeling of the coating. Simultaneously, abrupt changes in hardness, elastic modulus, and chemical composition between a single-layer coating and the aluminum substrate result in insufficient stability of the coating under friction or impact loads, making it difficult to meet the long-term service requirements of high-strength composite materials in complex working conditions.

[0004] Therefore, there is an urgent need to provide an aluminum-based composite material that can significantly improve surface hardness and wear resistance while ensuring lightweight properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose an aluminum-based composite material with a gradient structure surface reinforcement layer and its preparation method, thereby solving the technical problems of insufficient surface hardness and poor wear resistance of aluminum-based composite materials in the prior art.

[0006] In a first aspect, the present invention provides an aluminum-based composite material with a gradient structure surface reinforcement layer, comprising: a composite material body formed by a reinforcement and a matrix, and a gradient structure surface reinforcement layer generated in situ on the surface of the composite material body; wherein the reinforcement is a carbide, the matrix is ​​pure aluminum or an aluminum alloy, and the reinforcement is distributed in the matrix; the gradient structure surface reinforcement layer comprises: an aluminum nitride and / or aluminum carbide reinforcement layer, a nitrogen and / or carbon diffusion layer, and a transition layer located between the two.

[0007] Secondly, the present invention provides a method for preparing an aluminum-based composite material with a gradient structure surface reinforcement layer, comprising the following steps: Provide matrix materials and carbides; A precursor for aluminum-based composite materials was prepared by mixing matrix materials and carbides. Aluminum-based composite material precursors are subjected to surface strengthening and heat treatment to obtain aluminum-based composite materials with a gradient structure surface strengthening layer.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention enhances the overall hardness of aluminum-based composite materials by introducing carbide particles as reinforcement. A gradient-structured surface reinforcement layer is constructed in situ on the surface of the composite material. This layer consists of an outermost dense, high-hardness, and highly wear-resistant aluminum nitride and / or aluminum carbide reinforcement layer, a transition layer, and a nitrogen and / or carbon diffusion layer. The composition and hardness of the gradient-structured surface reinforcement layer continuously vary along the thickness direction, significantly mitigating residual stress between the coating and the composite material, improving the adhesion between the coating and the composite material, and preventing detachment. Simultaneously, the gradient-structured surface reinforcement layer further enhances the surface hardness and wear resistance of the aluminum-based composite material. The resulting aluminum-based composite material with the gradient-structured surface reinforcement layer is lightweight, high-hardness, and highly wear-resistant. The preparation process of this invention is simple and low-cost, facilitating industrial-scale mass production. Attached Figure Description

[0009] Figure 1 This is a SEM image of the aluminum-based composite material with a gradient structure surface reinforcement layer prepared in Example 1 of this invention; Figure 2 This is the XRD pattern of the aluminum-based composite material with a gradient structure surface reinforcement layer prepared in Example 1 of the present invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] In a first aspect, the present invention provides an aluminum-based composite material with a gradient structure surface reinforcement layer, comprising: a composite material body formed by a reinforcement and a matrix, and a gradient structure surface reinforcement layer generated in situ on the surface of the composite material body; wherein the reinforcement is a carbide, the matrix is ​​pure aluminum or an aluminum alloy, and the reinforcement is distributed in the matrix; the gradient structure surface reinforcement layer comprises: an aluminum nitride and / or aluminum carbide reinforcement layer, a nitrogen and / or carbon diffusion layer, and a transition layer located between the two.

[0012] This invention enhances the overall hardness of aluminum-based composite materials by introducing carbide particles as reinforcements. A gradient-structured surface reinforcement layer is constructed in situ on the surface of the composite material. This layer consists of an outermost dense, high-hardness, and highly wear-resistant aluminum nitride and / or aluminum carbide reinforcement layer, a transition layer, and a nitrogen and / or carbon diffusion layer. This allows the composition and hardness of the gradient-structured surface reinforcement layer to continuously vary along the thickness direction, significantly mitigating residual stress between the coating and the composite material, improving the adhesion between the coating and the composite material, and preventing detachment. Simultaneously, the gradient-structured surface reinforcement layer further enhances the surface hardness and wear resistance of the aluminum-based composite material. The resulting aluminum-based composite material with the gradient-structured surface reinforcement layer is lightweight, high-hardness, and highly wear-resistant.

[0013] In this embodiment, the carbide includes at least one metallic element selected from Ta, Si, B, Hf, Ti, Zr, Nb, etc., and carbon.

[0014] In this embodiment, the carbides include, but are not limited to, at least one of binary carbides such as TaC, SiC, B4C, HfC, TiC, ZrC, and NbC, and / or at least two of Ta, Si, B, Hf, Ti, Zr, and Nb forming multi-component carbides with carbon.

[0015] In this embodiment, the particle size D50 of the carbide is 1-50 μm.

[0016] In this embodiment, the carbide undergoes a pre-oxidation treatment, which includes: pre-oxidizing the carbide at 200-1000℃ for 1-20 hours in an air atmosphere, with a heating rate of 5-20℃ / min. This invention, by pre-oxidizing the carbide, eliminates free carbon and non-stoichiometric carbon, thereby reducing harmful interfacial brittle products between the reinforcement and Al at high temperatures and improving interfacial bonding.

[0017] In this embodiment, the Vickers hardness of the aluminum-based composite material with the gradient structure surface reinforcement layer is 400-3000 HV, and the room temperature wear rate is 1.6 × 10⁻⁶. -8 Up to 7.0×10 -6 mm 3 / N·m.

[0018] Secondly, the present invention provides a method for preparing an aluminum-based composite material with a gradient structure surface reinforcement layer, comprising the following steps: S1. Provide matrix materials and carbides; S2. Prepare an aluminum-based composite material precursor by mixing the matrix material and carbide; S3. Surface strengthening and heat treatment are performed on the aluminum-based composite precursor to obtain an aluminum-based composite material with a gradient structure surface strengthening layer.

[0019] This invention involves surface strengthening treatment of aluminum-based composite precursors to form an in-situ gradient structure surface strengthening layer on the composite surface (an outermost dense, high-hardness, and highly wear-resistant aluminum nitride and / or aluminum carbide strengthening layer, a transition layer, and a nitrogen and / or carbon diffusion layer). This allows the composition and hardness of the strengthening layer to continuously vary along the thickness direction, significantly mitigating residual stress between the coating and the substrate. Simultaneously, the gradient strengthening layer further enhances the surface hardness and wear resistance of the aluminum-based composite material, enabling it to exhibit more stable load-bearing capacity and wear resistance during friction and wear. The resulting aluminum-based composite material is lightweight, high-hardness, and highly wear-resistant.

[0020] In this embodiment, the matrix material includes elemental aluminum and optional alloying elements, including but not limited to at least one of zinc, magnesium, copper, silicon, manganese, chromium, zirconium, titanium, and other elements. This invention does not limit the form of the matrix material; those skilled in the art can select it according to actual conditions, such as elemental powder, elemental sheet, elemental block, etc.

[0021] In this embodiment, the carbide is pre-oxidized, and the pre-oxidation process includes: pre-oxidizing the carbide at 200-1000℃ for 1-20h, the atmosphere of the pre-oxidation process is air, and the heating rate is 5-20℃ / min.

[0022] In this embodiment, the mass of the carbide is 5%-55% of the mass of the matrix material, including but not limited to 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, etc.

[0023] In this embodiment, an aluminum-based composite material precursor is prepared by mixing the matrix material and carbides using a stirred casting method.

[0024] In this embodiment, the preparation of an aluminum-based composite material precursor by mixing a matrix material and a carbide includes: heating and melting the matrix material, then mixing and stirring it with the carbide, and finally casting and cooling it to obtain the aluminum-based composite material precursor.

[0025] Preferably, the mixing temperature is 600-700℃, the mixing time is 20-40 minutes, and the mixing is carried out under a protective atmosphere. This invention does not limit the type of protective atmosphere; those skilled in the art can select it according to the actual situation, for example, argon or similar gas.

[0026] In this embodiment, the surface strengthening treatment methods include, but are not limited to, at least one of gas nitriding treatment, gas carbonization treatment, microwave plasma nitriding treatment, and microwave plasma carbonization treatment.

[0027] Preferably, the surface strengthening treatment includes: first, treating with ammonia gas at a flow rate of 20-25 sccm and a temperature of 300-350℃ for 2-8 hours; then treating with ammonia gas at a flow rate of 60-100 sccm and a temperature of 480-500℃ for 4-16 hours; then treating with ammonia gas at a flow rate of 30-40 sccm and a temperature of 420-460℃ for 6-14 hours; then treating with ammonia gas at a flow rate of 10-15 sccm and a temperature of 350-400℃ for 6-10 hours; and finally cooling to room temperature with ammonia gas at a flow rate of 10-30 sccm.

[0028] Preferably, the surface strengthening treatment includes: first, treating with argon gas at a flow rate of 20-25 sccm and a temperature of 300-350℃ for 2-8 hours; then treating with argon gas at a flow rate of 10-30 sccm, methane gas at a flow rate of 60-100 sccm and a temperature of 480-500℃ for 4-16 hours; then treating with argon gas at a flow rate of 10-30 sccm, methane gas at a flow rate of 30-40 sccm and a temperature of 420-460℃ for 6-14 hours; then treating with argon gas at a flow rate of 10-30 sccm, methane gas at a flow rate of 10-15 sccm and a temperature of 350-400℃ for 6-10 hours; and finally cooling to room temperature with the furnace using argon gas at a flow rate of 10-30 sccm and methane gas at a flow rate of 10-30 sccm.

[0029] Preferably, the surface strengthening treatment includes: evacuating the microwave plasma reaction chamber to a vacuum level of 1×10⁻⁶. -2 Pa below (preferably ≤5×10) -3 First, the plasma is ignited with argon gas at a flow rate of 10-30 sccm and microwave power of 200-400 W, and treated at a substrate temperature of 300-350℃ for 20-40 min. Then, it is treated with ammonia gas at a flow rate of 60-100 sccm, microwave power of 600-1000 W, and substrate temperature of 460-500℃ for 70-140 min. After that, it is treated with ammonia gas at a flow rate of 10-30 sccm, microwave power of 400-600 W, and substrate temperature of 400-450℃ for 30-60 min. Finally, the microwave is turned off, and the plasma is cooled to room temperature with argon gas at a flow rate of 10-30 sccm and ammonia gas at a flow rate of 10-30 sccm.

[0030] Preferably, the surface strengthening treatment includes: evacuating the microwave plasma reaction chamber to a vacuum level of 1×10⁻⁶. -2 Pa below (preferably ≤5×10) -3First, the plasma is ignited with argon gas at a flow rate of 10-30 sccm and microwave power of 200-400 W, and treated at a substrate temperature of 300-350℃ for 20-40 min. Then, it is treated with argon gas at a flow rate of 10-30 sccm, methane at a flow rate of 60-100 sccm, microwave power of 600-1000 W, and substrate temperature of 460-500℃ for 70-140 min. After that, it is treated with argon gas at a flow rate of 10-30 sccm, methane at a flow rate of 10-30 sccm, microwave power of 400-600 W, and substrate temperature of 400-450℃ for 30-60 min. Finally, the microwave is turned off, and the furnace is cooled to room temperature with argon gas at a flow rate of 10-30 sccm and methane at a flow rate of 10-30 sccm.

[0031] In this invention, unless otherwise specified, the heating rate and cooling rate in each stage of the surface strengthening treatment are 5-10℃ / min.

[0032] In this invention, the surface strengthening treatment is carried out through multi-stage coordinated control of temperature and reactive gas flow rate, rather than a single constant process parameter. By controlling the reaction conditions in stages, it is beneficial to form a dense strengthening layer, a transition layer, and a diffusion layer sequentially on the material surface, thereby constructing a gradient structure in which the composition and properties continuously change along the thickness direction, reducing the residual stress between the strengthening layer and the substrate, and improving the stability of the surface strengthening layer.

[0033] For conventional gas nitriding or gas carburizing processes, the reaction process does not rely on plasma activation. The surface strengthening process employs multi-stage temperature and gas flow rate coordinated control, divided into four stages: The first stage uses an inert protective atmosphere or a low partial pressure reaction atmosphere at a relatively low temperature to activate and stabilize the material surface, promoting the uniform adsorption of reactive elements on the material surface and reducing the suddenness of surface reactions; The second stage accelerates the reaction kinetics by increasing the treatment temperature and the reactive gas flow rate, rapidly forming a dense aluminum nitride or aluminum carbide strengthening layer on the material surface; The third stage performs a transition treatment under moderate temperature and moderate reactive gas flow rate conditions, gradually balancing the surface reaction and the inward diffusion process; The fourth stage further reduces the reactive gas flow rate and appropriately lowers the treatment temperature, extending the diffusion time and promoting the continuous diffusion of reactive elements into the matrix, thereby obtaining a gradient strengthening layer with stable structure and continuously changing composition.

[0034] For microwave plasma nitriding or carbide processes, the reaction process is divided into three stages: In the initial stage, argon gas is introduced and plasma is ignited under low temperature and low microwave power conditions to clean and activate the material surface and establish a stable plasma discharge environment. This effectively removes adsorbed contaminants and weakly bound oxide layers from the sample surface, increases surface energy, and introduces active sites that are conducive to subsequent diffusion, resulting in a uniform activated state on the material surface. This provides conditions for the uniform adsorption, initial diffusion, and dense layering of reactive elements after the introduction of reactive gases, avoiding the formation of loose or brittle structures due to excessively rapid surface reactions. In the intermediate stage, the reaction kinetics are accelerated by increasing microwave power, reaction temperature, and reactive gas flow rate, forming a dense and high-hardness aluminum nitride or aluminum carbide reinforced layer on the material surface. Finally, in the third stage, the surface reaction rate is suppressed by reducing microwave power and appropriately reducing the reactive gas flow rate and temperature, promoting further diffusion of reactive elements into the matrix, thereby constructing a gradient transition layer with continuously varying composition and properties along the thickness direction.

[0035] Furthermore, the nitriding stage and / or microwave plasma nitriding stage of this invention utilizes a single NH3 for nitriding, leveraging the thermal decomposition of NH3 to provide an active nitrogen source and H2 with reducing / protective effects, achieving a stable nitriding effect without the need for additional inert gases. In the carbonization stage and / or microwave plasma carbonization stage of this invention, since CH4 is prone to rapid thermal decomposition at high temperatures, using only CH4 can easily lead to excessively high carbon potential, resulting in free carbon deposition / carbon buildup and a narrowed reaction window, which is detrimental to the controllable formation of the dense layer and gradient diffusion layer. By using a composite gas of CH4 and argon for carbonization, the partial pressure of CH4 is reduced by argon dilution and the effect of the carrier gas, resulting in a smoother carbon supply and improved process repeatability.

[0036] In this embodiment, the heat treatment includes: first performing a solution treatment, then rapidly water cooling to room temperature, and then performing an aging treatment.

[0037] Preferably, the solution treatment temperature is 400-550℃, the solution treatment time is 2-6 hours, the solution treatment atmosphere is air, and the heating rate is 5-10℃ / min. This invention, through solution treatment, ensures the complete dissolution of alloying elements such as zinc, magnesium, and copper in the aluminum alloy matrix and eliminates microstructural inhomogeneities that may be introduced during surface nitriding or carburizing. After solution treatment, the material is rapidly water-cooled to room temperature to obtain a supersaturated solid solution structure.

[0038] Preferably, the aging treatment temperature is 100-180℃, the aging treatment time is 8-30h, the aging treatment atmosphere is air, and the heating rate is 5-10℃ / min. This invention, through aging treatment, precipitates a dispersed reinforcing phase in the matrix, thereby improving the overall strength and toughness of the composite material and achieving good mechanical property matching with the surface gradient reinforcement layer.

[0039] Example 1 A method for preparing a B4C / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 104.7g of dried B4C (which can also be written as B4C) p The sample was spread in a crucible and heated to 200°C in an oven at a heating rate of 5°C / min, and held for 1 hour in an air atmosphere.

[0040] (2) A metal mixture with a total mass of 1167.57g (including: 1057.84 parts pure aluminum, 59.54 parts elemental zinc, 24.51 parts elemental magnesium, 14.01 parts elemental copper, 4.41 parts elemental silicon, 3.43 parts elemental manganese, 2.64 parts elemental chromium, 0.60 parts elemental zirconium, and 0.59 parts elemental titanium) was heated and melted to 650℃, and pretreated B4C was added. The mixture was stirred for 30 minutes under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0041] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically ground and ultrasonically cleaned, then dried and placed in an atmosphere furnace for nitriding under an ammonia atmosphere: First, a low ammonia flow rate of 20 sccm was used for pretreatment, and the furnace temperature was increased to 350°C at a heating rate of 5°C / min and held at this temperature for 2 hours; then, the furnace temperature was increased to 480°C at a heating rate of 5°C / min, while the ammonia flow rate was increased from 20 sccm to 80 sccm, and the temperature was held at 480°C. The furnace was treated continuously at 0℃ and an ammonia flow rate of 80 sccm for 4 hours. Then, the furnace temperature was lowered and stabilized at 450℃ at a cooling rate of 10℃ / min, and the ammonia flow rate was reduced from 80 sccm to 30 sccm. The furnace was then treated under these conditions for 6 hours. Finally, the furnace temperature was lowered to 400℃ at a cooling rate of 5℃ / min, and the ammonia flow rate was adjusted to 10 sccm. The furnace was then treated under these conditions for another 6 hours. After the treatment was completed, heating was stopped, and the furnace was allowed to cool naturally to room temperature under a protective atmosphere of 10 sccm ammonia.

[0042] (4) The above-mentioned nitrided and cooled block was subjected to heat treatment. The solution treatment temperature was 470℃, the solution treatment time was 2.5h, the heating rate was 10℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was carried out. The aging treatment temperature was 145℃, the aging treatment time was 12h, the heating rate was 10℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0043] Example 2 A method for preparing a SiC / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 133.4g of dried SiC, spread it in a crucible, heat it to 400℃ in an oven at a heating rate of 10℃ / min, keep it at that temperature for 2h, and use air as the atmosphere.

[0044] (2) A metal mixture with a total mass of 1167.57g (including: 1057.84 parts pure aluminum, 59.54 parts elemental zinc, 24.51 parts elemental magnesium, 14.01 parts elemental copper, 4.41 parts elemental silicon, 3.43 parts elemental manganese, 2.64 parts elemental chromium, 0.60 parts elemental zirconium, and 0.59 parts elemental titanium) was heated and melted to 650℃, pretreated SiC was added, and the mixture was stirred for 30min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0045] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, then dried and placed in an atmosphere furnace. Pretreatment was first performed under an argon protective atmosphere, with the argon flow rate set to 20 sccm. The furnace temperature was raised to 320°C at a rate of 5°C / min and maintained at this temperature for 2 hours. Subsequently, while maintaining the argon flow, methane gas was introduced, and the furnace temperature was raised to 500°C at a rate of 5°C / min. The methane gas flow rate was adjusted to 80 sccm. The furnace was then pretreated at 500°C with an argon flow rate of 20 sccm and a methane flow rate of 80 sccm. The furnace was treated continuously for 4 hours at a methane gas flow rate of 80 sccm. Then, the furnace temperature was lowered and stabilized at 460°C at a cooling rate of 10°C / min, and the methane gas flow rate was reduced from 80 sccm to 30 sccm. The furnace was then treated under these conditions for 6 hours. Finally, the furnace temperature was lowered to 400°C at a cooling rate of 5°C / min, and the methane gas flow rate was maintained at 10 sccm. The furnace was then treated for another 6 hours. After the treatment was completed, heating was stopped, and the furnace was allowed to cool naturally to room temperature under a protective atmosphere of 10 sccm methane flow rate and 20 sccm argon gas flow rate.

[0046] (4) The above-mentioned carbonized and cooled block was subjected to heat treatment. The solution treatment temperature was 450℃, the solution treatment time was 3h, the heating rate was 10℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was carried out. The aging treatment temperature was 180℃, the aging treatment time was 8h, the heating rate was 10℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0047] Example 3 A method for preparing a TaC / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 602.4g of dried TaC, spread it in a crucible, heat it to 500℃ in an oven at a heating rate of 10℃ / min, keep it at that temperature for 2h, and use air as the atmosphere.

[0048] (2) A metal mixture with a total mass of 1172.18 g (including: 1062.01 parts pure aluminum, 59.58 parts elemental zinc, 24.61 parts elemental magnesium, 14.07 parts elemental copper, 4.50 parts elemental silicon, 3.50 parts elemental manganese, 2.70 parts elemental chromium, 0.61 parts elemental zirconium, and 0.60 parts elemental titanium) was heated and melted to 650°C. Pretreated TaC was added, and the mixture was stirred for 30 min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0049] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, dried, and placed in a microwave plasma reaction chamber, where a vacuum of 5 × 10⁻⁶ was applied. -3 Pa; then argon gas was introduced, with the argon gas flow rate set to 25 sccm. The plasma was ignited under microwave power of 300W, and the substrate temperature was raised to 320℃ at a heating rate of 5℃ / min. The substrate was treated under this condition for 20 min to complete plasma stabilization and surface pretreatment. After that, the gas was switched from argon to ammonia, and the ammonia gas flow rate was adjusted to 80 sccm. At the same time, the substrate temperature was raised to 470℃ at a heating rate of 5℃ / min, and the microwave power was increased to 800W. The substrate was treated under this condition for 70 min. Then, while maintaining the ammonia gas supply, the ammonia gas flow rate was reduced from 80 sccm to 30 sccm, and the microwave power was reduced from 800W to 500W. At the same time, the substrate temperature was lowered and stabilized at 420℃ at a cooling rate of 10℃ / min. The substrate was treated under this condition for another 30 min. After the treatment, the microwave power was turned off, and argon gas was introduced. The substrate was allowed to cool naturally to room temperature under a protective atmosphere of argon gas flow rate of 20 sccm and ammonia gas flow rate of 20 sccm.

[0050] (4) The above-mentioned nitrided and cooled block was subjected to heat treatment. The solution treatment temperature was 400℃, the solution treatment time was 2h, the heating rate was 5℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was carried out. The aging treatment temperature was 100℃, the aging treatment time was 30h, the heating rate was 5℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0051] Example 4 A method for preparing a (Hf, Ta)C / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 527.7g of dried (Hf, Ta)C powder, spread it in a crucible, heat it to 800℃ in an oven at a heating rate of 10℃ / min, keep it at that temperature for 10h, and use air as the atmosphere.

[0052] (2) A metal mixture with a total mass of 1172.18 g (including: 1062.01 parts pure aluminum, 59.58 parts elemental zinc, 24.61 parts elemental magnesium, 14.07 parts elemental copper, 4.50 parts elemental silicon, 3.50 parts elemental manganese, 2.70 parts elemental chromium, 0.61 parts elemental zirconium, and 0.60 parts elemental titanium) was heated and melted to 650°C. Pretreated (Hf, Ta)C powder was added, and the mixture was stirred for 30 min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0053] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, dried, and placed in an atmosphere furnace for nitriding under an ammonia atmosphere. First, a low ammonia flow rate of 20 sccm was used for pretreatment, and the furnace temperature was increased to 350°C at a heating rate of 5°C / min and held at this temperature for 8 hours. Then, the furnace temperature was increased to 480°C at a heating rate of 5°C / min, and the ammonia flow rate was increased from 20 sccm to 80 sccm. The mixture was then nitrided at 480°C under an ammonia atmosphere. The furnace was treated continuously for 16 hours at a flow rate of 80 sccm. Then, the furnace temperature was lowered and stabilized at 450°C at a cooling rate of 10°C / min, and the ammonia flow rate was reduced from 80 sccm to 40 sccm. The furnace was treated continuously for 14 hours under these conditions. Finally, the furnace temperature was lowered to 400°C at a cooling rate of 5°C / min, and the ammonia flow rate was adjusted to 15 sccm. The furnace was treated continuously for 10 hours under these conditions. After the treatment was completed, heating was stopped, and the furnace was allowed to cool naturally to room temperature under a protective atmosphere with an ammonia flow rate of 15 sccm.

[0054] (4) The above-mentioned nitrided and cooled block was subjected to heat treatment. The solution treatment temperature was 500℃, the solution treatment time was 2h, the heating rate was 10℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was carried out. The aging treatment temperature was 160℃, the aging treatment time was 8h, the heating rate was 5℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0055] Example 5 A method for preparing a (Hf, Ti)C / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 344.9g of dried (Hf, Ti)C powder, spread it in a crucible, heat it to 800℃ in an oven at a heating rate of 10℃ / min, keep it at that temperature for 10h, and use air as the atmosphere.

[0056] (2) A metal mixture with a total mass of 1172.18 g (including: 1062.01 parts of pure aluminum, 59.58 parts of elemental zinc, 24.61 parts of elemental magnesium, 14.07 parts of elemental copper, 4.50 parts of elemental silicon, 3.50 parts of elemental manganese, 2.70 parts of elemental chromium, 0.61 parts of elemental zirconium, and 0.60 parts of elemental titanium) was heated and melted to 650°C. Pretreated (Hf, Ti)C powder was added, and the mixture was stirred for 30 min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0057] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, dried, and placed in a microwave plasma reaction chamber, where a vacuum of 5 × 10⁻⁶ was applied. -3 Pa; then argon gas was introduced, with the argon flow rate set to 25 sccm. The plasma was ignited under a microwave power of 300W, and the substrate temperature was raised to 320°C at a heating rate of 5°C / min. The substrate was treated under this condition for 20 min to complete plasma stabilization and surface pretreatment. After that, the gas was switched from argon to ammonia, and the ammonia flow rate was adjusted to 80 sccm. At the same time, the substrate temperature was raised to 470°C at a heating rate of 5°C / min, and the microwave power was increased to 800W. The substrate was treated under this condition for 140 min. Subsequently, while maintaining the ammonia supply, the ammonia flow rate was reduced from 80 sccm to 30 sccm, and the microwave power was reduced from 800W to 500W. At the same time, the substrate temperature was lowered and stabilized at 420°C at a cooling rate of 10°C / min. The substrate was treated under this condition for another 60 min. After the treatment, the microwave power was turned off, and argon gas was introduced. The substrate was allowed to cool naturally to room temperature under a protective atmosphere of argon flow rate of 20 sccm and ammonia flow rate of 20 sccm.

[0058] (4) The above-mentioned nitrided and cooled block was subjected to heat treatment. The solution treatment temperature was 500℃, the solution treatment time was 2h, the heating rate was 10℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was carried out. The aging treatment temperature was 160℃, the aging treatment time was 8h, the heating rate was 5℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0059] Example 6 A method for preparing a (Ta, Ti)C / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 427.9g of dried (Ta, Ti)C powder, spread it in a crucible, heat it to 800℃ in an oven at a heating rate of 10℃ / min, keep it at that temperature for 10h, and use air as the atmosphere.

[0060] (2) A metal mixture with a total mass of 1172.18 g (including 1062.01 parts of pure aluminum, 59.58 parts of elemental zinc, 24.61 parts of elemental magnesium, 14.07 parts of elemental copper, 4.50 parts of elemental silicon, 3.50 parts of elemental manganese, 2.70 parts of elemental chromium, 0.61 parts of elemental zirconium, and 0.60 parts of elemental titanium) was heated and melted to 650°C. Pretreated (Ta, Ti)C powder was added, and the mixture was stirred for 30 min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0061] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, dried, and placed in a microwave plasma reaction chamber, where a vacuum of 5 × 10⁻⁶ was applied. -3 Pa; then argon gas was introduced, with the argon flow rate set to 25 sccm. The plasma was ignited under microwave power of 300W, and the substrate temperature was raised to 320℃ at a heating rate of 5℃ / min. The substrate was treated under these conditions for 40 min to complete plasma stabilization and surface pretreatment. Then, methane was introduced as the carbon source gas, with the gas flow rate adjusted to 20 sccm for argon and 70 sccm for methane. The substrate temperature was raised to 480℃ at a heating rate of 5℃ / min, and the microwave power was increased to 800W. The substrate was treated under these conditions for 140 min. Subsequently, while maintaining the argon gas supply at 20 sccm, the methane gas flow rate was reduced from 70 sccm to 25 sccm, and the microwave power was reduced from 800W to 500W. The substrate temperature was lowered and stabilized at 430℃ at a cooling rate of 10℃ / min. The substrate was treated under these conditions for another 60 min. After the treatment, the microwave power was turned off, and the substrate was allowed to cool naturally to room temperature under a protective atmosphere of 20 sccm for argon and 25 sccm for methane.

[0062] (4) The above-mentioned carbonized and cooled block is subjected to heat treatment. The solution treatment temperature is 500℃, the solution treatment time is 2h, the heating rate is 10℃ / min, the atmosphere is air, and then it is rapidly water-cooled to room temperature. After that, aging treatment is performed. The aging treatment temperature is 160℃, the aging treatment time is 8h, the heating rate is 5℃ / min, the atmosphere is air, and it is naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0063] Example 7 A method for preparing a (Ti, Zr, Hf, Nb, Ta) C / Al aluminum-based composite material with a gradient structure surface reinforcement layer includes the following steps: (1) Weigh 369.8g of dried (Ti, Zr, Hf, Nb, Ta)C powder, spread it in a crucible, heat it to 1000℃ in an oven at a heating rate of 20℃ / min, keep it at that temperature for 20h, and use air as the atmosphere.

[0064] (2) A metal mixture with a total mass of 1172.18 g (including: 1062.01 parts pure aluminum, 59.58 parts elemental zinc, 24.61 parts elemental magnesium, 14.07 parts elemental copper, 4.50 parts elemental silicon, 3.50 parts elemental manganese, 2.70 parts elemental chromium, 0.61 parts elemental zirconium, and 0.60 parts elemental titanium) was heated and melted to 650°C. Pretreated (Ti, Zr, Hf, Nb, Ta) C powder was added, and the mixture was stirred for 30 min under an argon atmosphere. After casting and cooling, the aluminum-based composite material precursor was obtained.

[0065] (3) The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished and ultrasonically cleaned, dried, and placed in an atmosphere furnace for nitriding under an ammonia atmosphere: First, a low ammonia flow rate of 20 sccm was used for pretreatment, and the furnace temperature was increased to 350°C at a heating rate of 5°C / min and held at this temperature for 8 hours; then, the furnace temperature was increased to 480°C at a heating rate of 5°C / min, while the ammonia flow rate was increased from 20 sccm to 80 sccm, and the temperature was held at 480°C. The furnace was treated continuously for 16 hours at an ammonia flow rate of 80 sccm. Then, the furnace temperature was lowered and stabilized at 450℃ at a cooling rate of 10℃ / min, and the ammonia flow rate was reduced from 80 sccm to 40 sccm. The furnace was then treated for another 14 hours under these conditions. Finally, the furnace temperature was lowered to 400℃ at a cooling rate of 5℃ / min, and the ammonia flow rate was adjusted to 15 sccm. The furnace was then treated for another 10 hours under these conditions. After the treatment was completed, heating was stopped, and the furnace was allowed to cool naturally to room temperature under a protective atmosphere of 15 sccm ammonia.

[0066] (4) The above-mentioned nitrided and cooled block was subjected to heat treatment. The solution treatment temperature was 550℃, the solution treatment time was 2h, the heating rate was 10℃ / min, the atmosphere was air, and then it was rapidly water-cooled to room temperature. After that, aging treatment was performed. The aging treatment temperature was 100℃, the aging treatment time was 30h, the heating rate was 5℃ / min, the atmosphere was air, and it was naturally cooled down to finally obtain an aluminum-based composite material with a gradient structure surface reinforcement layer.

[0067] Example 8 A method for preparing a (Ti, Zr, Hf, Nb, Ta) C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as that in Example 7, except that in step (3), the gas nitriding treatment is replaced by microwave plasma nitriding treatment. The specific steps are as follows: The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished, ultrasonically cleaned, and dried. These blocks were then placed in a microwave plasma reaction chamber and evacuated to a vacuum of 5 × 10⁻⁶. -3 Pa; then argon gas was introduced, with the argon gas flow rate set to 25 sccm. The plasma was ignited under microwave power of 300W, and the substrate temperature was raised to 320℃ at a heating rate of 5℃ / min. The substrate was treated under this condition for 20 min to complete plasma stabilization and surface pretreatment. After that, the gas was switched from argon to ammonia, and the ammonia gas flow rate was adjusted to 80 sccm. At the same time, the substrate temperature was raised to 470℃ at a heating rate of 5℃ / min, and the microwave power was increased to 800W. The substrate was treated under this condition for 70 min. Then, while maintaining the ammonia gas supply, the ammonia gas flow rate was reduced from 80 sccm to 30 sccm, and the microwave power was reduced from 800W to 500W. At the same time, the substrate temperature was lowered and stabilized at 420℃ at a cooling rate of 10℃ / min. The substrate was treated under this condition for another 30 min. After the treatment, the microwave power was turned off, and argon gas was introduced. The substrate was allowed to cool naturally to room temperature under a protective atmosphere of argon gas flow rate of 20 sccm and ammonia gas flow rate of 20 sccm.

[0068] Example 9 A method for preparing a (Ti, Zr, Hf, Nb, Ta) C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as that in Example 7, except that in step (3), the gas nitriding treatment is replaced by microwave plasma carbonization treatment. The specific steps are as follows: The aluminum-based composite precursor was cut into blocks with a thickness of 0.3 cm, mechanically polished, ultrasonically cleaned, and dried. These blocks were then placed in a microwave plasma reaction chamber and evacuated to a vacuum of 5 × 10⁻⁶. -3Pa; then argon gas was introduced, with the argon flow rate set to 25 sccm. The plasma was ignited under a microwave power of 300W, and the substrate temperature was raised to 320℃ at a heating rate of 5℃ / min. The substrate was treated under these conditions for 40 min to complete plasma stabilization and surface pretreatment. Then, methane was introduced as the carbon source gas, with the gas flow rates adjusted to 20 sccm for argon and 70 sccm for methane. The substrate temperature was raised to 480℃ at a heating rate of 5℃ / min, and the microwave power was increased to 800W. The substrate was treated under these conditions for 140 min. Subsequently, the methane gas flow rate was reduced from 70 sccm to 25 sccm, and the microwave power was reduced from 800W to 500W. The substrate temperature was lowered and stabilized at 430℃ at a cooling rate of 10℃ / min. The substrate was treated under these conditions for another 60 min. After the treatment, the microwave power was turned off, and the substrate was allowed to cool naturally to room temperature under a protective atmosphere of 20 sccm for argon and 25 sccm for methane.

[0069] Example 10 A method for preparing a B4C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as in Example 1, except that step 1 is not included.

[0070] Example 11 A method for preparing a B4C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as that in Example 1, except that in step (3), a non-segmented surface nitriding treatment is carried out in an ammonia atmosphere, the ammonia flow rate is constant at 30 sccm, the furnace temperature is constant at 450℃, and the treatment is carried out continuously for 18h.

[0071] Example 12 A method for preparing a B4C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as that in Example 1, except that in step (3), the surface nitriding treatment is carried out in an ammonia atmosphere. The ammonia flow rate is constant at 30 sccm throughout the treatment process and does not change with the stage. The temperature and time program is the same as that in Example 1, that is, firstly, the treatment is carried out at 350℃ for 2 hours, then the temperature is increased to 480℃ for 4 hours, then the temperature is reduced to 450℃ for 6 hours, and finally the temperature is reduced to 400℃ for 6 hours.

[0072] Example 13 A method for preparing a (Ti, Zr, Hf, Nb, Ta) C / Al aluminum matrix composite material with a gradient structure surface reinforcement layer is the same as that in Example 9, except that the microwave plasma carbonization parameters in step (3) are set as follows: carbonization is carried out without staged control, that is, under constant gas flow rates of argon flow rate of 20 sccm and CH4 flow rate of 50 sccm, microwave power is constant at 700W, matrix temperature is constant at 465℃, continuous treatment is carried out for 200min, and microwave is turned off after treatment.

[0073] Example 14 A method for preparing a (Ti, Zr, Hf, Nb, Ta) C / Al aluminum-based composite material with a gradient structure surface reinforcement layer is the same as that in Example 9, except that the microwave plasma carbonization parameters in step (3) are set as follows: the methane gas flow rate is set to a constant value, that is, the argon gas flow rate is set to 20 sccm and the CH4 flow rate is set to 50 sccm. First, it is treated at 480℃ and 800W for 140 min, and then treated at 430℃ and 500W for 60 min.

[0074] Testing and Evaluation The prepared aluminum-based composite material samples were wire-cut into appropriate sizes for hardness testing, tribological testing, microstructure analysis, and XRD analysis. Specifically, a Wilson Tukon 1202 Vickers hardness tester was used to measure the macroscopic hardness of the aluminum-based composite material. The load was set to 50g, and the loading time was 15s. To avoid errors, each sample was measured 5 times, and the average value was taken. A Rtec MFT-5000 tribological testing machine was used to perform linear reciprocating tribological testing on the aluminum-based composite material. A 6mm diameter GCr15 steel ball was used in the tribological experiment, with a normal load of 5N, a friction rate of 0.032m / s, an amplitude of 5mm, and a friction time of 1800s. The microstructure of the aluminum-based composite material was characterized using SEM, and the phase composition was characterized using X-ray diffraction. The results are shown in Table 1 and [Table data missing]. Figure 1-2 As shown. An aluminum alloy prepared using the metal mixture in Example 1 as a raw material is used as a control example.

[0075] Table 1 Mechanical properties of samples obtained in each embodiment

[0076] As shown in Table 1, the aluminum-based composite materials with gradient structure surface reinforcement layers prepared in Examples 1-14 of this invention have a Vickers hardness of 400-3000 HV and a room temperature wear rate of 1.6 × 10⁻⁶ HV. -8 Up to 7.0×10 -6 mm 3 / N·m indicates that the present invention significantly improves the hardness and wear resistance of the composite material, and expands the scope of performance research and application of aluminum-based composite materials.

[0077] Compared with Example 1, Example 10 did not perform pre-oxidation treatment on B4C particles, resulting in the ineffective removal of residual free carbon and non-stoichiometric carbon phases on the particle surface during subsequent nitriding. These carbon phases tend to participate in reactions or accumulate at the interface between the particles and the Al matrix, forming brittle interface products with poor continuity. This weakens the interfacial bonding strength and easily generates micropores or localized loose areas. Under frictional loads, these areas are more prone to spalling and abrasive grain shedding, resulting in reduced surface hardness, poorer wear resistance, and ultimately a significantly higher wear rate compared to Example 1.

[0078] Compared with Example 1, in Example 11, no segmented nitriding was performed during the nitriding stage. The surface hardness of the prepared aluminum-based composite material decreased and the room temperature wear rate increased, indicating that segmented nitriding is beneficial to improving the hardness and wear resistance of the aluminum-based composite material.

[0079] Compared with Example 1, in the nitriding stage of Example 12, segmented nitriding was carried out under a constant ammonia flow rate. The hardness of the prepared aluminum-based composite material decreased and the room temperature wear rate increased, indicating that controlling the ammonia flow rate in the segmented nitriding stage is also beneficial to further improve the hardness and wear resistance of the aluminum-based composite material.

[0080] Compared with Example 9, the microwave plasma carbonization stage of Example 13 did not involve segmented carbonization. The hardness of the prepared aluminum-based composite material decreased significantly and the room temperature wear rate increased, indicating that segmented carbonization is beneficial to improving the hardness and wear resistance of the aluminum-based composite material.

[0081] Compared with Example 9, in the microwave plasma carbonization stage of Example 14, segmented carbonization was carried out under a constant methane gas flow rate. The hardness of the prepared aluminum-based composite material was significantly reduced and the room temperature wear rate was increased. This indicates that controlling the CH4 flow rate in the segmented carbonization stage is also beneficial to further improve the hardness and wear resistance of the aluminum-based composite material.

[0082] Please see Figure 1 ,pass Figure 1 (a) It can be seen that the boron carbide particles and the aluminum matrix are tightly bonded in the aluminum matrix composite material prepared in Example 1 of the present invention, there are very few micropores in the composite material, and there is no debonding phenomenon between the particles and the matrix, and the matrix is ​​relatively clean. Figure 1 (b) Boron carbide particles are uniformly dispersed in an aluminum matrix at low magnification; Figure 1 (c) The overall thickness of AlN is about 5 μm. The coating has good adhesion to the aluminum substrate and the coating is relatively smooth with no peeling. Figure 1(d) Line scan characterization analysis of the coating revealed that the Al and N contents exhibited opposite trends, with the Al content increasing closer to the aluminum matrix. The composite material surface formed an AlN gradient structure layer that gradually transitioned from the outside to the inside, and its composition and hardness varied continuously along the thickness direction. (See also...) Figure 2 The figure shows the (111), (200), and (220) series peaks of FCC-α-Al and the characteristic peaks of B4C rhombohedral crystals. However, no obvious interfacial reaction phase peaks were detected in the figure, indicating that no obvious brittle products were generated at the interface of the aluminum-based composite material prepared in Example 1 of this invention. The above results prove the successful preparation of the aluminum-based composite material with a gradient structure surface reinforcement layer of this invention.

[0083] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An aluminum matrix composite having a gradient structured surface reinforcement layer, characterized by, include: The composite material body formed by the reinforcement and the matrix, and the gradient structure surface reinforcement layer generated in situ on the surface of the composite material body; wherein, The reinforcing agent is a carbide, the matrix is ​​pure aluminum or an aluminum alloy, and the reinforcing agent is distributed in the matrix; The gradient structure surface reinforcement layer includes: an aluminum nitride and / or aluminum carbide reinforcement layer, a nitrogen and / or carbon diffusion layer, and a transition layer located between the two.

2. The aluminum matrix composite having a gradient structured surface reinforcement layer according to claim 1, wherein The carbide comprises at least one metallic element selected from Ta, Si, B, Hf, Ti, Zr, and Nb, and carbon; and / or, The carbide is at least one of binary carbides selected from TaC, SiC, B4C, HfC, TiC, ZrC, and NbC, and / or at least two of Ta, Si, B, Hf, Ti, Zr, and Nb forming a multi-component carbide with carbon; and / or, The particle size D50 of the carbide is 1-50 μm.

3. The aluminum matrix composite having a gradient structured surface reinforcement layer according to claim 1, wherein The carbide is pre-oxidized, and the pre-oxidation process includes: pre-oxidizing the carbide at 200-1000℃ for 1-20h, wherein the atmosphere of the pre-oxidation process is air, and the heating rate is 5-20℃ / min.

4. A method of producing an aluminum matrix composite having a gradient structure surface reinforcement layer according to any one of claims 1 to 3, characterized by, Includes the following steps: Provide matrix materials and carbides; The matrix material and the carbide are mixed to prepare an aluminum-based composite material precursor; The aluminum-based composite material precursor is subjected to surface strengthening and heat treatment to obtain an aluminum-based composite material with a gradient structure surface strengthening layer.

5. The method for preparing the aluminum-based composite material with a gradient structure surface reinforcement layer according to claim 4, characterized in that, The matrix material includes elemental aluminum and optionally alloying elements, wherein the alloying elements are at least one selected from zinc, magnesium, copper, silicon, manganese, chromium, zirconium, and titanium.

6. The method for preparing the aluminum-based composite material with a gradient structure surface reinforcement layer according to claim 4, characterized in that, The carbide undergoes a pre-oxidation treatment, the pre-oxidation treatment process comprising: pre-oxidizing the carbide at 200-1000℃ for 1-20 hours, wherein the atmosphere of the pre-oxidation treatment is air, and the heating rate is 5-20℃ / min; and / or, The mass of the carbide is 5%-55% of the mass of the matrix material.

7. The method of claim 4, wherein the aluminum matrix composite having a gradient structured surface reinforcement layer is prepared by the steps of: providing a substrate; providing a plurality of reinforcing particles; and forming a gradient structured surface reinforcement layer on the substrate by depositing the plurality of reinforcing particles on the substrate. Aluminum matrix composite precursors were prepared by mixing matrix materials and carbides using a stirred casting method. And / or, The preparation of an aluminum-based composite material precursor by mixing a matrix material and a carbide includes: heating and melting the matrix material, then mixing and stirring it with the carbide, casting and cooling it to obtain the aluminum-based composite material precursor; wherein the mixing and stirring temperature is 600-700℃, the mixing and stirring time is 20-40 min, and the mixing and stirring is carried out under a protective atmosphere.

8. The method for preparing the aluminum-based composite material with a gradient structure surface reinforcement layer according to claim 4, characterized in that, The surface strengthening treatment method is at least one of gas nitriding, gas carbonization, microwave plasma nitriding, and microwave plasma carbonization.

9. The method for preparing the aluminum-based composite material with a gradient structure surface reinforcement layer according to claim 4, characterized in that, The surface strengthening treatment comprises: first, ammonia flow rate 20-25sccm, temperature 300-350℃, treatment 2-8h; then, ammonia flow rate 60-100sccm, temperature 480-500℃, treatment 4-16h; after that, ammonia flow rate 30-40sccm, temperature 420-460℃, treatment 6-14h; then, ammonia flow rate 10-15sccm, temperature 350-400℃, treatment 6-10h; finally, ammonia flow rate 10-30sccm, furnace cooling to room temperature; or, The surface strengthening treatment comprises: first, argon flow rate 20-25sccm, temperature 300-350℃, treatment 2-8h; then, argon flow rate 10-30sccm, methane gas flow rate 60-100sccm, temperature 480-500℃, treatment 4-16h; after that, argon flow rate 10-30sccm, methane gas flow rate 30-40sccm, temperature 420-460℃, treatment 6-14h; then, argon flow rate 10-30sccm, methane gas flow rate 10-15sccm, temperature 350-400℃, treatment 6-10h; finally, argon flow rate 10-30sccm, methane gas flow rate 10-30sccm, furnace cooling to room temperature; or, The surface strengthening treatment comprises: vacuuming a microwave plasma reaction cavity to 1x10 -2 Pa, first igniting plasma at an argon gas flow rate of 10-30 seem, a microwave power of 200-400 W, a substrate temperature of 300-350 °C, and treating for 20-40 min; then treating at an ammonia gas flow rate of 60-100 seem, a microwave power of 600-1000 W, a substrate temperature of 460-500 °C, and treating for 70-140 min; thereafter treating at an ammonia gas flow rate of 10-30 seem, a microwave power of 400-600 W, a substrate temperature of 400-450 °C, and treating for 30-60 min; finally, turning off the microwave, and cooling to room temperature with an argon gas flow rate of 10-30 seem and an ammonia gas flow rate of 10-30 seem; or, The surface strengthening treatment comprises: vacuuming a microwave plasma reaction cavity to 1x10 -2 Below 1 Pa, first ignite plasma with argon flow rate 10-30 seem, microwave power 200-400 W, at substrate temperature 300-350 °C, for 20-40 min; then with argon flow rate 10-30 seem, methane flow rate 60-100 seem, microwave power 600-1000 W, substrate temperature 460-500 °C, for 70-140 min; then with argon flow rate 10-30 seem, methane flow rate 10-30 seem, microwave power 400-600 W, substrate temperature 400-450 °C, for 30-60 min; finally, turn off the microwave, with argon flow rate 10-30 seem, methane flow rate 10-30 seem, cool down to room temperature with the furnace.

10. The method for preparing the aluminum-based composite material with a gradient structure surface reinforcement layer according to claim 4, characterized in that, The heat treatment comprises: first, solid solution treatment, then rapid water cooling to room temperature, and then aging treatment; wherein, The temperature of the solid solution treatment is 400-550℃, the time of the solid solution treatment is 2-6h, the atmosphere of the solid solution treatment is air, and the heating rate is 5-10℃ / min; and / or, The temperature of the aging treatment is 100-180℃, the time of the aging treatment is 8-30h, the atmosphere of the aging treatment is air, and the heating rate is 5-10℃ / min.

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