Powder forged gradient material and method of making the same

Abstract

The application discloses a kind of powder forging gradient materials and preparation method thereof, belong to powder metallurgy technical field, the method includes: the powder of aluminium-containing alloy is with corresponding transition layer aluminium alloy powder, after layer-by-layer powder laying or powder filling, it is pressed into gradient material green body, after sintering, forging, obtain powder forging gradient material;The powder of aluminium-containing alloy is aluminium alloy powder or aluminium alloy mixed powder;Aluminium alloy mixed powder is prepared by mixing aluminium alloy powder with reinforcing phase particles;The powder of aluminium-containing alloy is at least three;When layer-by-layer powder laying, corresponding transition layer aluminium alloy powder is laid between each two layers of the powder of aluminium-containing alloy layer.The application can accurately control material composition and microstructure, carry out powder forging at low temperature, can reduce material defect, improve compactness and overall performance.Through the gradient design of material composition, interface topography and organizational structure, the strength and toughness of the material are improved, the utilization rate is high, the production process is environmentally friendly, and has wide industrial application potential.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a powder forging gradient material and its preparation method. Background Technology

[0002] With the rapid development of modern industry, the demand for new high-performance materials in the field of materials science is increasing. Aluminum alloys, due to their excellent properties such as lightweight, high strength, and corrosion resistance, are widely used in aerospace, automotive, and electronics industries. However, the performance of traditional single aluminum alloy materials is often limited under special working environments (such as high temperature and high pressure), making it difficult to meet the higher requirements of materials under special conditions. Therefore, the development of high-performance aluminum alloy composite materials and their preparation technologies is of great significance.

[0003] Gradient materials exhibit continuous or layered variations in their microstructure and properties. This material design effectively improves the mechanical properties and fatigue resistance of materials under complex environments, and has gradually become a research hotspot in materials science, with broad application potential in aerospace, energy, and biomedicine. However, current methods for preparing gradient materials mainly include vapor deposition, plasma spraying, powder metallurgy, and centrifugal casting. Each of these methods has its drawbacks. Vapor deposition has a low deposition rate and may produce flammable, explosive, or toxic gases under certain conditions, causing significant environmental pollution, and also requires sophisticated equipment. Plasma spraying suffers from high carrier gas costs, strict requirements on the quality of the sprayed material, and poor interlayer bonding. Centrifugal casting has a relatively narrow application range, applicable only to specific metals and ceramics, and suffers from poor internal surface quality, large machining allowances, and limitations when fabricating irregularly shaped parts.

[0004] To address the technical challenges of existing gradient material production processes, such as environmental pollution, high costs, and difficulty in controlling material performance, there is an urgent need to find a new powder forging gradient material and its preparation method to achieve gradient design of material composition and microstructure, thereby significantly improving the overall performance of the material. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a powder forging gradient material and its preparation method, so as to solve the technical problems of environmental pollution, high cost and difficulty in controlling the material properties in the production process of existing gradient materials. Through gradient design of material composition and microstructure, the comprehensive properties such as strength and toughness of the material are significantly improved, and the application of aluminum alloys in a wider range of fields is expanded.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing powder forging gradient materials, comprising the following steps:

[0008] Aluminum alloy powder and corresponding transition layer aluminum alloy powder are layered or filled with powder, pressed into a gradient material green blank, sintered, and forged to obtain powder forging gradient material.

[0009] The aluminum alloy-containing powder is either aluminum alloy powder or a mixture of aluminum alloy powders;

[0010] Aluminum alloy composite powder is prepared by mixing aluminum alloy powder with reinforcing phase particles;

[0011] There are at least three types of aluminum alloy powders;

[0012] During the layer-by-layer powder application, a corresponding transition layer of aluminum alloy powder is laid between every two layers of aluminum alloy powder.

[0013] Preferably, the aluminum alloy powder is a mixture of elemental powder and pre-alloyed powder;

[0014] The elemental powder is one or more of Al powder and Sn powder;

[0015] The pre-alloyed powder is one or more of Al-50Zn powder, Al-50Mg powder, Al-Mg powder, Al-50Si powder, and Al-50Cu powder;

[0016] The aluminum alloy powder is of the 2-series, 6-series, or 7-series; the particle size of the aluminum alloy powder is 2~30 μm;

[0017] The purity of both the elemental powder and the pre-alloyed powder is greater than 99.5%.

[0018] More preferably, the particle size of Al powder is 20~35 μm, the particle size of Sn powder is 38 μm, the particle size of Al-50Zn powder is 30 μm, the particle size of Al-50Mg powder is 20 μm, the particle size of Al-Mg powder is 20 μm, the particle size of Al-50Si powder is 48 μm, and the particle size of Al-50Cu powder is 20 μm.

[0019] Preferably, the transition layer aluminum alloy powder is Al-Mg powder or a mixed powder prepared by mixing powder containing aluminum alloy on both sides with Al-Mg powder;

[0020] The Al-Mg powder is laid with a thickness of 1-3 mm; the mass fraction of Mg in the Al-Mg powder is 0.1%-1.0%.

[0021] In the mixed powder, the aluminum alloy powders on both sides are mixed in a volume ratio of (1-3):(3-1); in the mixed powder, the mass fraction of Al-Mg powder is 0.5%-1.0%, and the mass fraction of Mg element in Al-Mg powder is 0.1%-0.5%.

[0022] Preferably, in the aluminum alloy mixed powder, the mass ratio of aluminum alloy powder to reinforcing phase particles is 1:(0-0.25).

[0023] The reinforcing phase particles are SiC particles; the particle size of the SiC particles is 5~10μm and the purity is greater than 99.5%.

[0024] Preferably, the pressing conditions are: first pressing with a small pressure of 0.5-5MPa, and then pressing with a large pressure of 140-210MPa;

[0025] The thickness ratio between two adjacent layers is 0.5-5. When pressing vertically along the length direction, a multi-layer powder spreading method is adopted, and when pressing horizontally along the thickness direction, a multi-layer powder filling method is selected.

[0026] More preferably, when pressing vertically along the length direction, aluminum alloy powder and corresponding transition layer aluminum alloy powder are laid vertically one by one, and pressed under low pressure and then pressed under high pressure to obtain gradient material green blank.

[0027] When pressing laterally along the thickness direction, powder is filled layer by layer laterally by inserting a partition cavity. The space between the partition cavities is filled with aluminum alloy powder, and the space inside the partition cavity is filled with the corresponding transition layer aluminum alloy powder. After removing the partition cavity, it is pressed again to obtain a gradient material green blank. The material of the partition cavity is nylon, and the wall thickness of the partition cavity is 0.2-1mm.

[0028] Preferably, the sintering temperature is 576-630 ℃; the sintering time is 60-90 min; and the density of each layer after sintering is 80%-95%.

[0029] Preferably, the forging conditions are: first, hold at 475-510 ℃ for 15-60 min, and then perform closed-die forging.

[0030] The present invention also discloses a powder forging gradient material, which is prepared by the above-described method for preparing powder forging gradient materials.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a method for preparing gradient materials using powder forging. Different aluminum alloy powders and corresponding transition layer aluminum alloy powders are pressed into green blanks through a layer-by-layer powder layering process. The green blanks are then sintered, and finally, the sintered material is forged. By controlling the composition of the aluminum alloy powders, gradient materials with different structural characteristics are obtained. Compared with other preparation methods, the powder forging method for preparing gradient composite materials exhibits a series of significant advantages. First, this method enables precise control of material composition and microstructure. By mixing and layer-by-layer adding powder raw materials with different particle sizes and compositions, it is easy to achieve direct design of the proportional composition and thickness of each layer on a macroscopic scale, and precise control of multi-level gradients, such as the continuous evolution of the composition and structure at the layer-to-layer interface. Layer-by-layer low-pressure pressing or the design of partition cavities for easy powder filling both contribute to precise control of layer thickness and obtaining clear and continuous layer-to-layer interfaces. Second, the powder forging method is performed at low temperatures, effectively reducing material defects such as porosity and shrinkage cavities, and improving the density and overall performance of the material. Furthermore, powder forging offers high process flexibility, allowing for adjustments to sintering and forging conditions such as time, temperature, and pressure based on varying material properties to meet the needs of preparing diverse composite materials. Economically, powder forging boasts high material utilization, achieving near-net-shape forming and reducing material waste. Environmentally, its relatively low sintering and forging temperatures result in low energy consumption and minimal harmful emissions, aligning with green manufacturing and sustainable development requirements. In summary, powder forging demonstrates promising application prospects in the preparation of gradient composite materials due to its advantages, including precise composition control, reduced material defects, process flexibility, material savings, and environmental friendliness.

[0033] This invention also discloses a powder forging gradient material prepared by the above-mentioned method, which exhibits several advantages compared with traditional aluminum-based composite materials. First, through the gradient design of performance and structure, the material can better adapt to varying working environments, such as designing a high-hardness surface layer in areas requiring high wear resistance while maintaining sufficient toughness and load-bearing capacity internally. Second, this structural gradient helps reduce thermal stress, improves the material's stability at high temperatures, reduces crack formation and propagation, and thus enhances fatigue resistance. Furthermore, the gradient design optimizes the bonding of material interfaces, especially the design of the partition cavity, which enables the direct construction of a large-area, wave-shaped interlocking interface and a continuous small-component gradient interface, reducing the risk of debonding and delamination, and improving overall strength and durability. The design of the interface transition layer further promotes the formation of a continuous micro-composition and microstructure gradient through diffusion during subsequent treatments such as solution treatment and aging, enhancing the coordination between layers during deformation, thereby greatly improving the overall performance of the material. The gradient material also significantly improves wear resistance and corrosion resistance, making it more reliable for use in harsh environments. Their designability meets customization needs, allowing for the creation of material regions with different functions tailored to specific applications, which is particularly important in high-end manufacturing. Simultaneously, these composite materials maintain lightweight while enhancing the strength and rigidity of specific areas, making them significant for industries seeking both lightweight and high strength, such as aerospace and automotive manufacturing. Overall, gradient materials outperform traditional aluminum-based composites in mechanical, thermal, durability, fatigue, and corrosion resistance, demonstrating broader application potential and higher performance levels. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the process of preparing a green blank by layer-by-layer powder forging of (2024-5SiC)-6061-7075 gradient material in Example 1 of the present invention;

[0035] Figure 2 This is a hardness variation distribution diagram of the powder forging (2024-5SiC)-6061-7075 gradient material in Example 1 of the present invention;

[0036] Figure 3 This is a schematic diagram of the powder forging process for preparing green blanks from 2024-(2024-5SiC)-(2024-10SiC) gradient materials in Embodiment 2 of the present invention.

[0037] Figure 4 This is a hardness variation distribution diagram of the 2024-(2024-5SiC)-(2024-10SiC) gradient material for powder forging in Example 2 of the present invention. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0040] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0041] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0042] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0043] In this invention, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" indicates that all real numbers between "6~22" have been listed in this document, and "6~22" is simply a shortened representation of these numerical combinations.

[0044] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0045] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0046] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0047] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0048] This invention provides a method for preparing powder forging gradient materials, comprising the following steps:

[0049] Step 1: Prepare aluminum alloy powder and aluminum alloy mixed powder

[0050] Aluminum alloy powder is a mixture of elemental powder and pre-alloyed powder. The elemental powder includes Al powder and Sn powder, and the pre-alloyed powder includes Al-50Zn powder, Al-50Mg powder, Al-Mg powder (Mg element mass fraction 0.1%-0.5%), Al-50Si powder and Al-50Cu powder. The purity of the above elemental powder and pre-alloyed powder is greater than 99.5%.

[0051] The particle size of Al powder is 20~35 μm, that of Sn powder is 38 μm, that of Al-50Zn powder is 30 μm, that of Al-50Mg powder is 20 μm, that of Al-Mg powder is 20 μm, that of Al-50Si powder is 48 μm, and that of Al-50Cu powder is 20 μm.

[0052] Aluminum alloy powders include 2-series, 6-series, and 7-series.

[0053] According to the requirements, the prepared aluminum alloy powder is mixed with the reinforcing phase particles to obtain aluminum alloy mixed powder. The mass ratio of aluminum alloy powder to reinforcing phase particles is 1:(0-0.25). The reinforcing phase particles are SiC particles with a particle size of 5~10μm and a purity greater than 99.5%.

[0054] When preparing the transition layer aluminum alloy powder, the aluminum alloy powders of two adjacent layers are mixed uniformly at a volume ratio of 3:1 or 1:3, and an additional 0.5%-1.0% Al-Mg powder (Mg element mass fraction 0.1-0.5%) is added.

[0055] Step 2: Prepare gradient material green body

[0056] Select three or more types of aluminum alloy powder and their corresponding transition layer aluminum alloy powder. Each layer is laid vertically in sequence with a certain thickness ratio and pressed under low pressure each time, thus achieving parallel stacking of the layers. The pressing pressure is 0.5-5 MPa, followed by high-pressure pressing at 140-210 MPa.

[0057] Alternatively, a partition cavity can be inserted, and powder can be filled layer by layer in the transverse direction. Aluminum alloy powder is filled between the partition cavities, and corresponding transition layer aluminum alloy powder is filled inside the partition cavity. After removing the partition cavity, it is pressed to obtain a gradient material green blank. The partition cavity material is nylon with a wall thickness of 0.2-1mm and a pressing pressure of 140-210MPa.

[0058] Step 3: Sinter the gradient material green body under an inert atmosphere to obtain the sintered gradient material.

[0059] The green compact was sintered under N2 atmosphere to obtain a sintered gradient material.

[0060] The sintering temperature of the green body is 576-630 ℃; the sintering time is 60-90 min, so that the density of each layer is 80%-95% after sintering.

[0061] Step 4: Forge the sintered gradient material to obtain powder forged gradient material.

[0062] First, the sintered gradient material is held at 475-510℃ for 15-60 minutes, and then closed-die forging is performed to obtain powder forging gradient material.

[0063] Preferably, the powder forging gradient material is subjected to thermomechanical treatment, including solution treatment, deformation and aging processes.

[0064] This invention discloses a method for preparing powder-forged gradient materials. The method involves selecting three or more aluminum alloy powders as needed, layering them vertically according to a specific thickness ratio, and then pressing them under low pressure to achieve parallel stacking of layers. These layers are then pressed under high pressure to obtain a gradient material green blank. Alternatively, a partition cavity can be inserted, powder is filled horizontally layer by layer, the partition cavity is removed, and then the green blank is pressed again. The green blank is sintered in an inert gas atmosphere to obtain a sintered gradient material. The sintered material is then forged to obtain the powder-forged gradient material. This method allows for precise control of material composition and microstructure. The powder forging method is performed at low temperatures, reducing material defects and improving density and overall performance. Through gradient design of material composition, interface morphology, and microstructure, the comprehensive properties of the material, such as strength and toughness, are improved. The material has high utilization rate, the production process is environmentally friendly, and it has broad industrial application potential. Compared with traditional aluminum-based composite materials, gradient materials, by introducing gradual changes in performance and structure, allow for a gradual transition in the mechanical and thermal properties of the material surface and interior, enabling better adaptation to complex service environments. Furthermore, gradient materials possess high designability, allowing for the customization of materials with different functions in specific regions by controlling composition, structure, and processing to meet specific application requirements. This flexibility enables their application in a wider range of industrial sectors, particularly in high-end manufacturing fields with stringent material performance requirements.

[0065] In comparison, powder metallurgy offers significant advantages, making it a leader among various preparation methods. It boasts numerous benefits, including high cost-effectiveness, high production efficiency, low processing requirements, precise control over material properties, environmental friendliness, and flexible material combinations. Powder metallurgy can produce high-temperature resistant and extremely durable parts at a relatively low cost. Its net-formability often eliminates or minimizes machining, reducing secondary processing steps and effectively lowering labor and overall production costs. Furthermore, the process offers extremely high control precision, allowing for precise fine-tuning of comprehensive properties such as strength and toughness, which is crucial for applications with specific material property requirements. Powder metallurgy is also an extremely environmentally friendly process, with 97% of the materials used being converted into the final product, generating virtually no waste. Moreover, it can combine different metallic and non-metallic materials to create unique material combinations while avoiding complex metallurgical procedures.

[0066] It is worth mentioning that powder forging technology, as a significant innovation in the field of powder metallurgy, integrates advanced manufacturing processes from both powder metallurgy and precision forging. By heating and forging sintered powder metallurgy preforms in a closed die cavity, near-net-shape forming of parts is achieved. This technology not only significantly improves material utilization but also, through precision forging, substantially enhances the density and mechanical properties of the product, bringing its performance to or even exceeding that of traditional forgings. Powder forging technology has relatively low equipment requirements due to its lower forging temperatures and pressures, effectively reducing die wear and equipment costs. Furthermore, this technology simplifies the production process, eliminating cumbersome subsequent machining steps, and enabling high-efficiency, low-cost large-scale production, making it a highly promising and important development direction in the field of powder metallurgy.

[0067] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0068] Example 1

[0069] A method for preparing a powder forging gradient material includes the following steps:

[0070] Step 1: Prepare 2024 aluminum alloy powder. Mix 87.5% Al powder, 8.8% Al-50Mg powder, 3.2% Al-50Cu powder and 0.5% Sn powder evenly to form 2024 aluminum alloy powder with a particle size of 5 μm.

[0071] Then, the 2024 aluminum alloy powder was mixed with SiC particles with a particle size of 5 μm at a mass ratio of 95:5 to obtain 2024-5SiC aluminum alloy powder with a SiC mass fraction of 5%.

[0072] To prepare 6061 aluminum alloy powder, 96.1% Al powder, 0.5% Al-50Cu powder, 1.2% Al-50Si powder, 2% Al-50Mg powder and 0.2% Sn powder were mixed evenly by mass percentage to form 6061 aluminum alloy powder.

[0073] To prepare 7075 aluminum alloy powder, 80.2% Al powder, 11.3% Al-50Zn powder, 5.2% Al-50Mg powder, 3.1% Al-50Cu powder and 0.2% Sn powder were mixed evenly by mass percentage to form 7075 aluminum alloy powder with a particle size of 10 μm.

[0074] (2024-5SiC)-6061 aluminum alloy powder was prepared by selecting 2024-5SiC aluminum alloy powder and 6061 aluminum alloy powder at a volume ratio of 1:3, and additionally adding 0.5% Al-0.5Mg powder by mass fraction. The mixture was then homogeneous to obtain (2024-5SiC)-6061 aluminum alloy transition layer powder.

[0075] To prepare a 6061-7075 aluminum alloy mixed powder, 6061 aluminum alloy powder and 7075 aluminum alloy powder were selected in a volume ratio of 3:1, and 0.5% Al-0.5Mg powder was added by mass. The powder was mixed evenly to obtain a 6061-7075 aluminum alloy transition layer powder.

[0076] Step 2: Select 2024-5SiC aluminum alloy mixed powder, (2024-5SiC)-6061 aluminum alloy transition layer powder, 6061 aluminum alloy powder, 6061-7075 aluminum alloy transition layer powder and 7075 aluminum alloy powder in a thickness ratio of 1:0.2:1:0.2:1. Lay them up vertically one by one and press them with a pressure of 5MPa to make each layer stacked in parallel. Finally, press them under a pressure of 210 MPa to obtain a gradient material green blank.

[0077] Step 3: After sintering at 576℃ for 90 min under N2 atmosphere, a sintered gradient material is obtained, with each layer having a density of 80% after sintering.

[0078] Step 4: Hold the sintered gradient material at 510℃ for 30 min, and then perform closed-die forging to obtain powder forging (2024-5SiC)-6061-7075 gradient material.

[0079] Figure 1 This is a schematic diagram of the process of preparing a green blank by layer-by-layer powder forging of the gradient material (2024-5SiC)-6061-7075 in Embodiment 1 of the present invention. As can be seen from the figure, by laying the gradient material layer by layer vertically and pressing it with small pressure, the layers can be stacked in parallel to obtain a gradient material with parallel interfaces.

[0080] Figure 2 This is a hardness variation distribution diagram of the powder forging (2024-5SiC)-6061-7075 gradient material in Example 1 of the present invention; it can be seen from the figure that the hardness of the material shows a certain variation, and there is no mixing of powders in different layers.

[0081] Example 2

[0082] A method for preparing a powder forging gradient material includes the following steps:

[0083] Step 1: Prepare 2024 aluminum alloy powder. Mix 87.5% Al powder, 8.8% Al-50Mg powder, 3.2% Al-50Cu powder and 0.5% Sn powder evenly to form 2024 aluminum alloy powder with a particle size of 5 μm.

[0084] Then, 2024 aluminum alloy powder was mixed with SiC particles with a particle size of 10 μm at mass percentages of 95:5 and 9:1, respectively, to obtain 2024-5SiC aluminum alloy powder and 2024-10SiC aluminum alloy powder with SiC mass fractions of 5% and 10%, respectively.

[0085] Step 2: Select 2024 aluminum alloy powder, 2024-5SiC aluminum alloy powder, 2024-10SiC aluminum alloy powder, and Al-0.5Mg powder. In a thickness ratio of 1:0.2:1:0.2:1, sequentially fill the partition cavity with 2024 aluminum alloy powder, Al-0.5Mg powder, 2024-5SiC aluminum alloy powder, Al-0.5Mg powder, and 2024-10SiC aluminum alloy powder layer by layer from bottom to top. After removing the partition, press the material under 210 MPa to obtain a gradient material green blank. The Al-0.5Mg powder layer thickness is 1.5 mm, and the partition thickness is 0.2 mm.

[0086] Step 3: After sintering at 576℃ for 90 min under N2 atmosphere, a sintered gradient material is obtained, with each layer having a density of 85% after sintering.

[0087] Step 4: Hold the sintered gradient material at 510℃ for 30 min, and then perform closed-die forging to obtain powder forged 2024-(2024-5SiC)-(2024-10SiC) gradient material.

[0088] Step 5: Perform thermomechanical treatment on the powder forged 2024-(2024-5SiC)-(2024-10SiC) gradient material. The process is to solution-solidify at 490℃ for 1 hour, then water-quench, followed by aging at 180℃ for 10 hours and air-cooling.

[0089] Figure 3 This is a schematic diagram of the powder forging process of 2024-(2024-5SiC)-(2024-10SiC) gradient material prepared into a green blank in Embodiment 2 of the present invention. As can be seen from the figure, the wavy area interlocking and the direct construction of the continuous small component gradient interface are realized through the partition cavity.

[0090] Figure 4 This is a hardness variation distribution diagram of the 2024-(2024-5SiC)-(2024-10SiC) gradient material forged by powder forging in Example 2 of the present invention; it can be seen from the figure that the hardness of the material shows a certain variation, and there is no mixing of powders in different layers.

[0091] Example 3

[0092] A method for preparing a powder forging gradient material includes the following steps:

[0093] Step 1: Prepare 6061 aluminum alloy powder. Mix 96.1% Al powder, 0.5% Al-50Cu powder, 1.2% Al-50Si powder, 2% Al-50Mg powder and 0.2% Sn powder evenly to form 6061 aluminum alloy powder with a particle size of 2 μm.

[0094] Then, 6061 aluminum alloy powder was mixed with SiC particles with a particle size of 5 μm at mass ratios of 9:1 and 4:1, respectively, to obtain 6061-10SiC aluminum alloy powder and 6061-20SiC aluminum alloy powder with SiC mass fractions of 10% and 20%, respectively.

[0095] Step 2: Select 6061 aluminum alloy powder, 6061-10SiC aluminum alloy powder, 6061-20SiC aluminum alloy powder, and Al-0.1Mg powder. In a thickness ratio of 1:0.5:1:0.5:1, sequentially fill the partition cavity with layers of 6061 aluminum alloy powder, Al-0.1Mg powder, 6061-10SiC aluminum alloy powder, Al-0.1Mg powder, and 6061-20SiC aluminum alloy powder horizontally from bottom to top. After removing the partition, first press with a pressure of 0.5 MPa, then press with a pressure of 140 MPa to obtain a gradient material green body. The mass fraction of Al-0.1Mg powder is 0.75%, and the Al-0.1Mg powder layer thickness is 1 mm. The partition thickness is 0.5 mm.

[0096] Step 3: After sintering at 590℃ for 85 min under N2 atmosphere, a sintered gradient material is obtained, and the density of each layer after sintering is 80%.

[0097] Step 4: Hold the sintered gradient material at 475℃ for 60 min, and then perform closed-die forging to obtain powder forged 6061-(6061-10SiC)-(6061-20SiC) gradient material.

[0098] Example 4

[0099] A method for preparing a powder forging gradient material includes the following steps:

[0100] Step 1: Prepare 7075 aluminum alloy powder. Mix 80.2% Al powder, 11.3% Al-50Zn powder, 5.2% Al-50Mg powder, 3.1% Al-50Cu powder and 0.2% Sn powder evenly to form 7075 aluminum alloy powder with a particle size of 15 μm.

[0101] Then, the 7075 aluminum alloy powder was mixed with SiC particles with a particle size of 8 μm at a mass percentage of 85:15 to obtain 7075-15SiC aluminum alloy powder with a SiC mass fraction of 15%.

[0102] Step 2: Select 7075 aluminum alloy powder, 7075-15SiC aluminum alloy powder, and Al-0.2Mg powder. In a thickness ratio of 1:0.5:1:0.5:1, sequentially fill the partition cavity with layers of 7075-15SiC aluminum alloy powder, Al-0.2Mg powder, 7075 aluminum alloy powder, Al-0.2Mg powder, and 7075-15SiC aluminum alloy powder horizontally from bottom to top. After removing the partition, first press with a pressure of 1 MPa, then press with 160 MPa to obtain a gradient material green blank. The mass fraction of Al-0.2Mg powder is 1%, and the Al-0.2Mg powder layer thickness is 2 mm. The partition thickness is 1 mm.

[0103] Step 3: After sintering at 600℃ in N2 atmosphere for 70 min, a sintered gradient material is obtained, and the density of each layer after sintering is 90%.

[0104] Step 4: Hold the sintered gradient material at 480℃ for 40 min, and then perform closed-die forging to obtain powder forged (7075-15SiC)-7075-(7075-15SiC) gradient material.

[0105] Example 5

[0106] A method for preparing a powder forging gradient material includes the following steps:

[0107] Step 1: Prepare 6063 aluminum alloy powder. Mix 96.4% Al powder, 1.2% Al-50Mg powder, 1% Al-50Cu powder, 0.9% Al-50Si powder, and 0.5% Sn powder evenly to form 6063 aluminum alloy powder with a particle size of 30 μm.

[0108] To prepare 7085 aluminum alloy powder, 77.8% Al powder, 3.16% Al-50Mg powder, 2.12% Al-50Cu powder, 15.92% Al-50Zn powder, 0.8% Al-Si powder, and 0.2% Sn powder were mixed evenly by mass percentage to form 7085 aluminum alloy powder.

[0109] To prepare 2024 aluminum alloy powder, 87.5% Al powder, 8.8% Al-50Mg powder, 3.2% Al-50Cu powder and 0.5% Sn powder were mixed evenly by mass percentage to form 2024 aluminum alloy powder with a particle size of 5 μm.

[0110] 6063-7085 aluminum alloy powder was prepared by selecting 6063 aluminum alloy powder and 7085 aluminum alloy powder at a volume ratio of 1:3, and additionally adding 1% Al-0.5Mg powder by mass. The powder was mixed evenly to obtain 6063-7085 aluminum alloy transition layer powder.

[0111] A 7085-2024 aluminum alloy mixed powder was prepared by selecting 7085 aluminum alloy powder and 2024 aluminum alloy powder in a volume ratio of 3:1, and additionally adding 1% Al-0.5Mg powder by mass. The powder was mixed evenly to obtain a 7085-2024 aluminum alloy transition layer powder.

[0112] Step 2: Select 6063 aluminum alloy powder, 6063-7085 aluminum alloy transition layer powder, 7085 aluminum alloy powder, 7085-2024 aluminum alloy transition layer powder and 2024 aluminum alloy powder according to the thickness ratio of 1:0.5:1:0.5:1, lay them up vertically one by one and press them with a pressure of 3MPa respectively, so that each layer is stacked in parallel, and finally press them under a pressure of 180 MPa to obtain a gradient material green blank.

[0113] Step 3: After sintering at 630℃ for 60 min under N2 atmosphere, a sintered gradient material is obtained, and the density of each layer after sintering is 95%.

[0114] Step 4: Hold the sintered gradient material at 500℃ for 15 minutes, and then perform closed-die forging to obtain powder forging 6063-7085-2024 gradient material.

[0115] In summary, this invention provides a method for preparing powder-forged gradient materials, aiming to improve the comprehensive properties of materials, such as strength and toughness, through gradient design of material composition, interface morphology, and microstructure. The method includes the following steps: selecting three or more aluminum alloy powders as needed, layering them vertically according to a certain thickness ratio, and pressing them under low pressure sequentially to achieve parallel stacking of layers, followed by high-pressure pressing to obtain a gradient material green blank; or inserting a partition cavity, filling it with powder layer by layer laterally, removing the partition cavity, and then pressing it to obtain a gradient material green blank. The green blank is sintered in an inert gas atmosphere to obtain a sintered gradient material. The sintered material is then forged to obtain the powder-forged gradient material. This invention's preparation method can precisely control the material composition and microstructure. The powder forging method is performed at low temperatures, which can reduce material defects and improve density and overall performance. This method has high material utilization, an environmentally friendly production process, and broad industrial application potential.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a powder forging gradient material, characterized in that, Includes the following steps: Aluminum alloy powder and corresponding transition layer aluminum alloy powder are layered or filled with powder, pressed into a gradient material green blank, sintered, and forged to obtain powder forging gradient material. The aluminum alloy-containing powder is aluminum alloy powder or aluminum alloy mixed powder; The aluminum alloy mixed powder is prepared by mixing aluminum alloy powder with reinforcing phase particles; The aluminum alloy powder contains at least three types; During the layer-by-layer powder spreading process, a corresponding transition layer of aluminum alloy powder is spread between every two layers of aluminum alloy powder. The aluminum alloy powder is a mixture of elemental powder and pre-alloyed powder; The elemental powder is one or more of Al powder and Sn powder; The pre-alloyed powder is one or more of Al-50Zn powder, Al-Mg powder, Al-50Si powder, and Al-50Cu powder; The mixture is 2-series, 6-series, or 7-series aluminum alloy powder; the particle size of the aluminum alloy powder is 2~30 μm; The purity of both the elemental powder and the pre-alloyed powder is greater than 99.5%; The transition layer aluminum alloy powder is Al-Mg powder or a mixed powder prepared by mixing powder containing aluminum alloy on both sides with Al-Mg powder; When the transition layer aluminum alloy powder is Al-Mg powder, the Al-Mg powder layer thickness is 1-3 mm; the mass fraction of Mg element in the Al-Mg powder is 0.1%-1.0%. In the mixed powder, the aluminum alloy powders on both sides are mixed in a volume ratio of (1-3):(3-1); in the mixed powder, the mass fraction of Al-Mg powder is 0.5%-1.0%, and the mass fraction of Mg element in the Al-Mg powder is 0.1%-0.5%; The pressing conditions are: first press with a small pressure of 0.5-5MPa, and then press with a large pressure of 140-210MPa. The thickness ratio between two adjacent layers is 0.5-5. When pressing vertically along the length direction, a multi-layer powder spreading method is adopted, and when pressing horizontally along the thickness direction, a multi-layer powder filling method is selected. When pressing vertically along the length direction, aluminum alloy powder and corresponding transition layer aluminum alloy powder are laid vertically one after another, and pressed with small pressure and then pressed with large pressure to obtain gradient material green blank. When pressing laterally along the thickness direction, powder is filled layer by layer laterally by inserting a partition cavity. The space between the partition cavities is filled with aluminum alloy powder, and the cavity inside the partition cavity is filled with a corresponding transition layer of aluminum alloy powder. After removing the partition cavity, it is pressed again to obtain a gradient material green blank. The partition cavity is made of nylon and has a wall thickness of 0.2-1mm. The forging conditions are as follows: first, hold at 475-510 ℃ for 15-60 min, and then perform closed-die forging.

2. The method for preparing powder forging gradient materials according to claim 1, characterized in that, The particle size of the Al powder is 20~35 μm, the particle size of the Sn powder is 38 μm, the particle size of the Al-50Zn powder is 30 μm, the particle size of the Al-50Mg powder is 20 μm, the particle size of the Al-Mg powder is 20 μm, the particle size of the Al-50Si powder is 48 μm, and the particle size of the Al-50Cu powder is 20 μm.

3. The method for preparing powder forging gradient materials according to claim 1, characterized in that, In the aluminum alloy mixed powder, the mass ratio of aluminum alloy powder to reinforcing phase particles is 1:(0-0.25). The reinforcing phase particles are SiC particles; the particle size of the SiC particles is 5~10μm and the purity is greater than 99.5%.

4. The method for preparing powder forging gradient materials according to claim 1, characterized in that, The sintering temperature is 576-630 ℃; the sintering time is 60-90 min; and the density of each layer after sintering is 80%-95%.

5. A powder forging gradient material, characterized in that, It is prepared by the powder forging gradient material preparation method according to any one of claims 1 to 4.

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