Additive manufacturing high-toughness heat-resistant aluminum alloy material and preparation method thereof

Abstract

The invention discloses a preparation method of a high-toughness heat-resistant aluminum alloy material for additive manufacturing. The preparation method comprises the following steps: S1, preparing an alloy powder mixture; s2, the evenly mixed alloy powder is dried and subjected to cold pressing to form a prefabricated block; s3, carrying out a reaction to generate nanoscale ceramic particles; s4, alloy ingots obtained after reaction are placed in a smelting device to be subjected to atomization powdering; and S5, powder obtained through atomization powder preparation is graded and dried, and nano ceramic particle reinforced aluminum-based composite material powder for additive manufacturing is obtained. S6, block printing is conducted on the aluminum-based composite material powder obtained in the step S5 through the laser powder bed melting technology; and S7, solid solution aging heat treatment and performance verification are conducted on the prepared aluminum-based composite material. According to the heat-resistant aluminum-based composite material powder prepared through the formula components and the process, an aluminum-based composite material block printed through a laser powder bed melting technology can be free of cracks, high in density, good in formability and high-temperature tensile property.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing aluminum alloy material preparation, and in particular to an additive manufacturing high-strength, high-toughness, and heat-resistant aluminum alloy material and its preparation method. Background Technology

[0002] The rapid development of strategic emerging industries such as aerospace and new energy vehicles has created an urgent demand for advanced materials that combine excellent heat resistance and lightweight properties. Lightweight, high-strength structural materials, represented by aluminum alloys, have become the most promising lightweight structural materials in additive manufacturing due to their excellent specific strength, outstanding thermal and electrical conductivity, and mature industrial application foundation. Al-Si alloys, with their excellent processability and formability, have become the most mature aluminum alloy material system for commercial application in additive manufacturing, achieving a series of landmark engineering application results. However, with the continuous expansion of industrial application scenarios, the insufficient overall mechanical properties of Al-Si alloys severely restrict their application in high-end fields such as aerospace, especially in large-size, high-load-bearing, and lightweight key components.

[0003] The limitations of additive manufacturing of Al-Si aluminum alloys in terms of strength and high-temperature performance have forced researchers to turn their attention to traditional high-strength aluminum alloy systems, such as the 2xxx (Al-Cu-Mg) and 7xxx (Al-Zn-Mg-Cu) series. However, these alloys face severe challenges in controlling metallurgical defects during additive manufacturing, which seriously restricts their industrial application. Taking typical alloys 2024 (2xxx series) and 7075 (7xxx series) as examples, their high alloying composition (Cu 4.4–5.0 wt.%, Zn 5.1–6.1 wt.%) results in a wide solidification temperature range of 150–200℃. Under the rapid melting and solidification conditions of additive manufacturing, they are prone to forming coarse dendritic structures, introducing ultra-high residual stress (locally reaching 300–450 MPa), causing defects such as interlayer cracking or porosity, leading to severe performance degradation. Regarding high-temperature performance, although the room temperature strength of alloy 7075 can reach 600-700 MPa, the nano-precipitated phases (such as η'-MgZn2) will rapidly coarsen under service conditions at 200℃, resulting in a significant decrease in strength. At 300℃, its strength drops to 10% of that at room temperature, which greatly limits its application in high-temperature service environments.

[0004] To address the problems of the existing technology mentioned above: This invention provides a high-strength, heat-resistant aluminum-based composite powder for additive manufacturing and its preparation method. The aluminum-based composite material block printed by laser powder bed melting technology is crack-free, has high density, good formability, and significantly improved high-temperature tensile properties. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-strength, high-toughness, and heat-resistant aluminum alloy materials by additive manufacturing. The heat-resistant aluminum-based composite material powder obtained by the above-mentioned formulation and process can be used to print aluminum-based composite material blocks using laser powder bed melting technology, which can achieve the advantages of being crack-free, having high density, good formability, and high-temperature tensile properties.

[0006] To achieve the above objectives, the following technical solutions are used: A method for preparing high-strength, high-toughness, and heat-resistant aluminum alloy materials by additive manufacturing. S1: The alloy powder mixture is subjected to high-energy ball milling to obtain a uniformly dispersed alloy powder mixture; S2: Dry the uniformly mixed alloy powder and cold press it into preforms; S3: The preform obtained in S2 is placed in a graphite mold and sintered under a vacuum atmosphere with multi-field coupling to induce an exothermic dispersion reaction to generate nano-sized ceramic particles. S4: The alloy ingot obtained after the reaction is placed in a melting device for atomization and powdering; S5: The powder obtained by atomization powdering is classified and dried to obtain nano-ceramic particle reinforced aluminum matrix composite material powder for additive manufacturing; S6: Use laser powder bed melting technology to print the aluminum-based composite material powder obtained in step S5 into bulk; S7: Perform solution aging heat treatment and performance verification on the prepared aluminum-based composite material.

[0007] As a further priority, in S3, The heating rate is 5-15℃ / min; The temperature is 680-750℃; Reaction time: 5-20 min; The reaction is carried out under vacuum (<10-3 Pa) or argon atmosphere.

[0008] As a further preferred option, the alloy powder mixture is a mixture of metal powder mixture and oxide powder mixture.

[0009] As a further preferred option, in S1, The metal powder mixture shall include at least the following components: High-purity Al powder; Cu powder; Mg powder; Ag powder; The oxide powder mixture includes at least the following components: TiO2 powder; B2O3 powder; TiO2 and B2O3 purity >99.9%; The molar ratio of B2O3 to TiO2 is 1:1.

[0010] As a further preferred option, in S3, the mass fractions of each element in the aluminum alloy are as follows: Cu: 3.5-4.5 wt.%; Mg: 0.15-0.35 wt.%; Ag: 0.50-1.50 wt.%; TiB2: 1.0-5.0 wt.%; The rest are Al.

[0011] As a further preferred option, the temperature inside the resistance drying oven in S2 is 80°C, and the drying time is 12 hours.

[0012] As a further priority, in S5, When the vacuum level is below 10⁻³ Pa, the preset temperature range is 800~1000℃.

[0013] When the vacuum level reaches below the preset vacuum level, an inert gas is introduced to atmospheric pressure. The inert gas is high-purity argon or nitrogen, and the gas flow rate is controlled at 10-200 L / min, with a gas atomization pressure of 4-10 MPa.

[0014] As a further preferred option, in S3, the ceramic-reinforced aluminum matrix composite powder obtained in S6 is dried and then sieved, and the average particle size of the aluminum matrix composite powder is 15-53 μm.

[0015] As a further priority, in S7, The energy density of the laser powder bed melting technology is between 50 and 80 J / mm3, the laser power is between 190 and 350 W, and the scanning speed is between 1000 and 2000 mm / s; The oxygen content is controlled below 0.200%; the substrate temperature is set to 120-180 ℃, and the layer thickness is set to 20 µm~40 µm.

[0016] As a further priority, In S7, the conditions for solution aging heat treatment are as follows: The solution treatment temperature for aluminum alloy materials is 505-525℃; the solution treatment time is 1.5-2.5 hours. Aging temperature: 135-175℃; aging time: 4-6 hours.

[0017] The present invention provides a method for preparing a high-strength, high-toughness, and heat-resistant aluminum alloy material by additive manufacturing, which has the following beneficial effects: 1) The heat-resistant aluminum-based composite powder of the present invention is prepared by in-situ self-generated nano-ceramic particles TiB2 with Al-Cu-Mg-Ag alloy as the matrix, and is used in the field of additive manufacturing of high-strength and high-toughness heat-resistant aluminum-based composite materials.

[0018] 2) The heat-resistant aluminum-based composite material of the present invention is based on the multi-field coupling assisted sintering technology of spark plasma sintering to introduce nano-ceramic particles in situ, which can achieve uniform dispersion of ceramic particles in the aluminum matrix. The ceramic particles are not only uniformly distributed on the surface of the matrix particles, but also exist and are uniformly distributed inside the matrix particles. In step S3 of this invention, an exothermic chemical reaction occurs: Al powder reacts with TiO2 and B2O3 to generate nano-sized TiB2 in situ. The above-mentioned high-temperature exothermic dispersion method enables TiO2, B2O3 and Al to react in situ to form the above-mentioned nano-sized TiB2. The basic reaction formula is as follows: 10Al+ 3TiO2 + 3B2O3 → 5Al2O3 + 3TiB2.

[0019] 3) Spark Plasma Sintering (SPS) is an advanced pressure sintering technology that involves loading metal powders into a mold made of materials such as graphite, applying a specific sintering power supply and pressing pressure using upper and lower die punches and energized electrodes, and using a low-voltage, high-current DC pulsed current to excite plasma to achieve rapid densification of the powder. This technology uses pulsed current to form a discharge plasma between powder particles, combined with axial pressure to reduce the sintering temperature, and features rapid heating (≥500℃ / min) and short sintering time (completed within minutes). Multi-field coupling assisted sintering technology based on spark plasma sintering can be used to prepare materials with fine-grained structures. Furthermore, the high sintering pressure promotes full reaction of the components, facilitates the dispersed distribution of nano-ceramic particles, and enhances sample densification.

[0020] 4) During the laser powder bed melting process, the heat-resistant aluminum-based composite powder of the present invention will generate a nano-reinforcing phase with extremely small size, such as Al2Cu phase, due to rapid cooling. The reinforcing phase is uniformly dispersed in the α-Al solid solution matrix, can form a low interfacial energy coherent interface with the matrix, and has a low coarsening rate, which is a heat-resistant reinforcing phase. 5) The heat-resistant aluminum-based composite powder system of the present invention introduces ceramic particles (TiB2) in situ. Ceramic particles typically have characteristics such as high hardness, high elastic modulus, and high melting point, forming a heterogeneous structure of "soft matrix + hard particles", which is beneficial to the synergistic improvement of strength and plasticity; moreover, the uniformly distributed ceramic particles can significantly change the solidification path of the matrix and compound, and as a heterogeneous nucleating agent, they can refine the grains, while significantly improving the thermal stress distribution during rapid solidification, effectively suppressing the generation of hot cracks, thereby improving the alloy's formability and heat resistance.

[0021] 6) The heat-resistant aluminum-based composite material for additive manufacturing of the present invention, compared with the prior art method, in step S3, uses in-situ self-generated ceramic particles to reinforce the aluminum-based composite material powder, thereby achieving uniform distribution of ceramic particles in the aluminum matrix. The in-situ self-generation of the present invention differs from the prior art, which uses mechanical mixing to incorporate nano-ceramic particles, resulting in uneven distribution and affecting the final molding performance. The bulk aluminum-based composite material printed using this powder has excellent high-temperature comprehensive mechanical properties. The high-temperature tensile strength of the heat-resistant aluminum alloy material at 250°C is above 250 MPa, and the elongation is above 10%. Based on the above properties, it can be widely used in aerospace, transportation and other fields. Attached Figure Description

[0022] Figure 1 This is a technical roadmap for the additive manufacturing method of high-strength, high-toughness, and heat-resistant aluminum alloy materials according to the present invention. Figure 2 This is a morphology diagram of the aluminum-based composite material powder prepared in the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention. Figure 3 In the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention, aluminum alloy powder is obtained by atomization in Example 1: Figure (a) is a cross-sectional morphology diagram of the powder particles; Figures (b) and (c) are EDS spectra of element Ti and element B in the cross-section of the powder particles, respectively. Figure 4 This is a photograph of the printed aluminum alloy block in Example 1 of the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention. Figure 5 This is a photograph of the microstructure of the printed aluminum alloy in Example 1, from the method for preparing high-strength, high-toughness, and heat-resistant aluminum alloy materials by additive manufacturing of the present invention. Figure 6 The tensile curve of the heat-treated aluminum alloy in Example 1 is shown in the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention. Figure 7 Metallographic photograph of the aluminum-based composite material powder printed in Comparative Example 1, which is used in the preparation method of additive manufacturing of high-strength, high-toughness, and heat-resistant aluminum alloy material of the present invention.

[0023] Figure 8 Metallographic photograph of the aluminum-based composite material powder printed in Comparative Example 2, which is used in the preparation method of additive manufacturing of high-strength, high-toughness, and heat-resistant aluminum alloy material of the present invention.

[0024] Figure 9 The tensile curve of the heat-treated aluminum alloy in Comparative Example 3 is shown in the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention.

[0025] Figure 10 This is a microstructure diagram of the aluminum alloy obtained by conventional hot pressing sintering in Comparative Example 4, which is part of the additive manufacturing method for high-strength, high-toughness, and heat-resistant aluminum alloy materials of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with embodiments and accompanying drawings: It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] Unless otherwise specified, the experimental or testing methods described in the embodiments of this invention are all conventional methods; unless otherwise specified, the reagents and / or materials are obtained from conventional commercial sources or prepared by conventional methods.

[0028] Example 1 The preparation process of a high-strength, high-toughness, and heat-resistant aluminum alloy material for additive manufacturing is as follows: Step 1) Weigh titanium dioxide, boron trioxide, and pure aluminum powder, magnesium powder, copper powder, and silver powder (all with a purity ≥ 99.9%) according to a certain mass ratio (after mixing, the mass fraction of copper powder is 4.0%, magnesium powder is 0.25%, silver powder is 1.0%, titanium dioxide is 3.2%, boron trioxide is 2.8%, and the remainder is aluminum powder), and then place them in an electric resistance furnace to dry. The drying temperature in the electric resistance furnace is 1500℃, and the temperature is maintained for 2 hours. The molar ratio of titanium dioxide to boron trioxide is 1:1 to ensure complete reaction of titanium dioxide and boron trioxide. Step 2) Place the dried mixed powder into a ball mill for ball milling; set the speed to 200 r / min and the time to 4h; Step 3) Press the uniformly mixed powder into cylindrical blocks with a diameter of 30 mm and a length of 100 mm at room temperature; Step 4) Sinter the cold-pressed preform in a discharge plasma sintering furnace, maintaining a vacuum of 10⁻² Pa; specifically, follow these steps: (1) Loading and preheating: The precast blocks are placed in a specially designed graphite mold that can be subjected to pressure and an electric field, and then placed in a vacuum sintering furnace and evacuated.

[0029] (2) Coupled heating stage: A heating rate of 15℃ / min can effectively suppress abnormal grain growth. The pressure parameters are divided into two stages: maintaining a pre-pressure of 10MPa before reaching 350℃, and then increasing the pressure to 50MPa and holding the pressure for 10 minutes when the temperature reaches 550℃. The termination temperature is set to 600℃. When this temperature is reached and constant temperature is started, discharge plasma sintering is started simultaneously. Specific sintering power supply and pressing pressure are applied by the upper and lower die punches and energized electrodes. The plasma is excited by a low-voltage, high-current DC pulse current to achieve rapid densification of the powder. A high DC pulse electric field (or low-voltage DC field) and axial pressure are applied.

[0030] (3) Triggering and temperature control: Under the coupled effect of an electric field (which promotes atomic diffusion and generates Joule heating) and pressure (which increases particle contact and promotes densification), the exothermic reaction is triggered prematurely. After the reaction occurs, this temperature and field-assisted conditions are maintained for 15-20 minutes to ensure the reaction is complete.

[0031] (4) Cooling: Remove the electric field and pressure, and cool the furnace to room temperature.

[0032] Materials with fine-grained (nanostructure) structures can be prepared using multi-field coupling assisted sintering technology based on spark plasma sintering. The reaction is rapid and the sintering pressure is high, which is conducive to the full reaction of each component. By inducing exothermic dispersion reaction, nano-ceramic particles are introduced in situ, which is beneficial to the dispersion distribution of nano-ceramic particles and the densification of the sample.

[0033] Traditional ceramic particle addition technology is based on the chemical mixing molten salt method, which involves adding potassium fluorotitanate and potassium fluoroborate during the aluminum alloy smelting process to induce the reaction K2TiF6 + KBF4 + Al → TiB2 + K3AlF3 + KAlF4. This reaction cycle is long and easily introduces impurities. In contrast, traditional mechanical mixing methods tend to cause ceramic particles to agglomerate and be distributed on the particle surface, preventing them from growing inside the particles. This affects the subsequent printing formability and mechanical properties, and the mixing time is long and the cost is high.

[0034] Step 5) Place the fully reacted nanostructured aluminum alloy ingot into a melting device for atomization and powdering; When the vacuum level reaches below the preset vacuum level of 10⁻³ Pa, argon gas is introduced to atmospheric pressure. The preset temperature is 900℃, and then the temperature is increased to the preset temperature at a rate of 10℃ / min. The melt is melted into an alloy liquid at a preset melting temperature, and then flows into the atomizing nozzle through a guide pipe. High-purity argon gas is used as the atomizing medium to spray and break the liquid into fine droplets, which then solidify into the original powder.

[0035] Argon gas flow rate: 20 L / min; gas atomization pressure: 4.5 MPa.

[0036] Step 6) The original powder is classified and sieved to obtain aluminum-based composite material powder with a particle size of 15~53µm; Step 7) Dry the sieved aluminum-based composite powder at 80°C for 12 hours. Step 8) Spread powder using a laser powder bed melting device, and then print the shape.

[0037] A unidirectional scanning strategy was employed, with a powder layer thickness of 30 µm, laser power of 230 W, scanning speed of 1200 mm / s, scanning spacing of 90 µm, angle increment of 67°, and area overlap set to 0.13 mm. The forming process was protected by argon gas with an oxygen content ≤0.200%, and the substrate preheating temperature was 150°C. After printing, the substrate was removed after cooling to room temperature.

[0038] Step 9) The printed titanium-aluminum alloy block was solution heat treated at 505℃ for 2.5h, then quenched, and then aged at 135℃ for 4h before being taken out for microstructure characterization and tensile testing.

[0039] Figure 1 This is a technical roadmap for Example 1; Figure 2 The figure shows the tensile curves of the heat-treated aluminum alloy. As can be seen from the figure, the aluminum alloy prepared in this embodiment has excellent mechanical properties. The tensile strength at room temperature (25℃) is 468MPa and the elongation is 7.6%; the tensile strength at 200℃ is 343MPa and the elongation is 13.3%; and the tensile strength at 250℃ is 266MPa and the elongation is 12.4%, showing excellent heat resistance.

[0040] Figure 3 The image shows a photograph of the printed aluminum alloy block in Example 1. As can be seen from the figure, the aluminum-based composite material (Al-Cu-Mg-Ag / TiB2) prepared by this method has good formability and no cracks are generated.

[0041] Figure 4 In the example, aluminum alloy powder obtained by atomization was analyzed by EDS scanning. The results showed that TiB2 was not only distributed on the particle surface but also appeared inside the particles, achieving a uniform dispersion of nano-ceramic particles in the aluminum alloy matrix. As a reinforcing phase and heterogeneous core, this significantly improves the heat resistance of additively manufactured aluminum alloys. Figure 5 The image shows the microstructure of the printed aluminum alloy in Example 1. As can be seen from the image, the printed aluminum alloy has a fine equiaxed grain structure with a small amount of submicron-sized TiB2 particles segregating at the grain boundaries. There are no microcracks, which helps to improve the formability and heat resistance.

[0042] Comparative Example 1: For TiB2-free ceramic particles, Al-Cu-Mg-Ag alloy powder was added, wherein the mass fractions of each element were: 4.0% copper powder, 0.25% magnesium powder, 1.0% silver powder, and the remainder was aluminum powder, the composition being the same or similar to that in Example 1. After melting and powder preparation (the process was the same as in Example 1), it was directly printed. The printing parameters were also the same as in Example 1, namely, a unidirectional scanning strategy, a powder layer thickness of 30µm, a laser power of 230W, a scanning speed of 1200mm / s, a scanning spacing of 90µm, an angle increment of 67°, and a region overlap of 0.13mm. Argon gas was used for protection during the forming process, with an oxygen content of ≤0.200% in the argon atmosphere. The substrate preheating temperature during the forming process was 150℃. After printing, the substrate was cooled and removed.

[0043] Metallographic characterization and photographs of the printed specimens show that obvious cracks appear in Al-Cu-Mg-Ag printing without TiB2 ceramic particle reinforcement. Figure 6 As shown, without the addition of a ceramic reinforcing phase, rapid cooling during the printing process can easily cause microscopic thermal stress, affecting printability and mechanical properties.

[0044] Therefore, comparing Example 1 and Comparative Example 1, it can be seen that the addition of TiB2 ceramic particles plays a key role in improving the printability and heat resistance of Al-Cu-Mg-Ag.

[0045] Comparative Example 2: An aluminum alloy composite powder (which can be used in additive manufacturing) is prepared as follows: Step 1) Weigh and mix the Al alloy powder obtained by melting and atomizing in Comparative Example 1 with TiB2 ceramic powder (average particle size of 20nm) in a certain ratio (mass ratio of aluminum alloy to TiB2 particles is 1:0.02). The mass fraction of TiB2 is 2.00%. The mixing process is completed in a mixer for 12 hours. Step 2) Dry the mechanically mixed powder in a vacuum oven at 80°C for 24 hours. Step 3) Powder is spread using a laser powder bed fusion device, followed by shaping. A unidirectional scanning strategy is employed, with a powder layer thickness of 30µm, laser power of 230W, scanning speed of 1200mm / s, scanning spacing of 90µm, angle increment of 67°, and area overlap set to 0.13mm. Argon gas is used for protection during the shaping process, with an oxygen content ≤0.200%. The substrate is preheated to 150℃ during shaping. The substrate is then removed after cooling.

[0046] Comparative Example 2 involves directly mixing aluminum alloy matrix powder with externally added ceramic particles, drying the resulting powder, and then performing additive manufacturing.

[0047] Figure 7 The image shows the morphology of the aluminum-based composite powder in Comparative Example 2. As can be seen from the image, the nanoparticles exist on the surface of the aluminum alloy matrix.

[0048] like Figure 8 The printed photograph shows obvious cracking in the printed block, indicating that the uneven distribution of the ceramic reinforcing phase can lead to stress concentration, causing cracking and affecting the final formability and mechanical properties.

[0049] A comparison of Comparative Examples 1 and 2 with Example 1 shows that the method of introducing ceramic particles through exothermic dispersion is superior to the method without adding ceramic particles or the method of adding them through mechanical mixing. Different degrees of thermal cracking were observed in Comparative Examples 1 and 2.

[0050] Multi-field coupling assisted sintering technology based on spark plasma sintering can be used to prepare fine-grained materials with nanostructures. Moreover, the high sintering pressure is conducive to the full reaction of each component. By inducing exothermic dispersion reaction, nano-ceramic particles are introduced in situ, which is beneficial to the dispersion distribution of nano-ceramic particles and the densification of the sample.

[0051] By inducing an exothermic diffusion reaction, nano-ceramic particles are introduced in situ, so that the ceramic particles are not only distributed on the particle surface, but also exist inside the particle. In the subsequent printing process, the uniformly distributed nano-ceramic particles can serve as nucleation centers, refine the grains, avoid micro-stress concentration and the generation of thermal cracks, and are beneficial to improving formability and high-temperature performance.

[0052] Comparative Example 3: The difference between Comparative Example 3 and Example 1 lies in the different post-printing solution aging process. (The solution heat treatment conditions for Example 1 are: solution heat treatment at 505℃ for 2.5h, quenching after heat treatment, and then aging heat treatment at 135℃ for 4h before taking it out; The solution treatment and aging conditions in Comparative Example 3 were as follows: solution treatment at 535℃ for 2.5 hours, followed by quenching and removal, and then aging heat treatment at 135℃ for 4 hours. The aluminum alloy printed in Example 1 was solution treated at 535°C for 2.5 hours, then quenched and removed. It was then subjected to aging heat treatment at 135°C for 4 hours and removed. The microstructure was then observed and the mechanical properties were tested.

[0053] Microstructural observation of the prepared powder revealed significant differences in grain structure after different solution-aging heat treatments. Higher heat treatment temperatures tended to lead to grain coarsening, which was detrimental to improving strength and plasticity at high temperatures. Figure 9As shown, at a solution treatment temperature of 535℃, the tensile strength at room temperature is 469 MPa with an elongation of 6.8%; at 200℃, the tensile strength is 321 MPa with an elongation of 12.1%; and at 250℃, the tensile strength is 249 MPa with an elongation decreasing to 8.2%, which is lower than the properties of the aluminum alloy after solution treatment at 505℃. This indicates that subsequent heat treatment plays a crucial role in the microstructure control and mechanical property improvement of additively manufactured aluminum alloys.

[0054] A comparison between Comparative Example 3 and Example 1 shows that: Controlling the solution treatment and aging conditions is also crucial for improving the performance of aluminum alloys. The solution treatment temperature (505°C) in Example 1 can effectively induce the precipitation of a large number of strengthening phases, thereby increasing the alloy strength. In Comparative Example 3, if the temperature is too high, the grains will coarsen, reducing both the alloy strength and plasticity. Insufficient high-temperature strengthening phases will lead to poor high-temperature performance.

[0055] contrast Figure 6 and Figure 9 The tensile curves at 250°C show that the strength and plasticity of the alloy sample in Example 1 are superior to those in Comparative Example 3.

[0056] Comparative Example 4: The process is the same as steps 1-3 in Example 1, except that in step 4, conventional hot isostatic pressing (HIP) is used instead of spark plasma sintering in the hot pressing sintering stage. The process is as follows: 1) The cold-pressed precast blocks are sintered in a vacuum hot-pressing sintering furnace, with the vacuum level maintained at 10. -2 Pa; Specifically: Loading and preheating: The precast blocks are placed in a specially made pressure-applying graphite mold, and then placed in a vacuum sintering furnace and evacuated.

[0057] 2) Pressurization stage: Pressurize the sample to 50 MPa at a rate of 5 MPa / min and maintain the pressure for 10 minutes; 3) Heating stage: After the pressure holding period, start heating. Increase the temperature to 600℃ at a rate of 15℃ / min to begin sintering. Maintain constant pressure during this period.

[0058] 4) Sintering stage: Maintain a temperature of 600℃ and a pressure of 50MPa for 15-20 minutes.

[0059] 5) Cooling: Remove temperature and pressure, and cool the furnace to room temperature.

[0060] The sample after conventional hot pressing sintering has a relatively coarse grain structure, which is a coarse-grained structure rather than a nanostructure, while the TiB2 particles generated by the reaction are mainly distributed at the grain boundaries (e.g., Figure 10 As shown in the figure, rather than inside the particles, this indicates that ordinary hot pressing sintering cannot achieve good dispersion of TiB2.

Claims

1. A method for preparing an additive manufactured high strength and toughness heat-resistant aluminum alloy material, characterized in that, S1: mixing alloy powder mixture by high-energy ball milling to obtain uniformly dispersed alloy powder mixture; S2: drying the above uniformly mixed alloy powder and cold-pressing into a preform; S3: placing the preform prepared in S2 into a mold and performing coupling assisted sintering on the preform under vacuum atmosphere to generate nanoscale ceramic particles through exothermic dispersion reaction; S4: placing the alloy ingot obtained after the reaction into a melting device for atomization powdering; S5: obtaining the nanoceramic particle reinforced aluminum matrix composite material powder for additive manufacturing through classification and drying of the powder obtained by atomization powdering; S6: bulk printing the aluminum matrix composite material powder obtained in step S5 using laser powder bed fusion technology; and S7: performing solid solution aging heat treatment and performance verification on the prepared aluminum matrix composite material. In S3, the heating rate is 5-15 ℃ / min; the temperature is 680-750 ℃; the reaction time is 5-20 min; the alloy powder mixture is a mixture of metal powder mixture and oxide powder mixture. In S1, the metal powder mixture at least includes the following components:

2. The method of claim 1, wherein the additive manufacturing of high strength-to- toughness heat resistant aluminum alloy material is characterized by: high-purity Al powder; Cu powder; Mg powder; Ag powder; The reaction was carried out in vacuum (<10 -3 Pa) or argon atmosphere.

3. The method of claim 1, wherein the additive manufacturing of high strength-to- toughness heat resistant aluminum alloy material is characterized by: the oxide powder mixture at least includes the following components:

4. The method of claim 3, wherein the additive manufacturing of high strength-to- toughness heat resistant aluminum alloy material is characterized by, TiO2 powder; B2O3 powder; the purity of TiO2 and B2O3 is >99.9%; the molar ratio of B2O3 to TiO2 is 1:

1. In S3, the mass fraction of each element of the aluminum alloy is as follows: Cu: 3.5-4.5 wt.%; Mg: 0.15-0.35 wt.%; Ag: 0.50-1.50 wt.%; TiB2: 1.0-5.0 wt.%; the rest is Al. In S2, the temperature in the resistance drying oven is 80 ℃, and the drying time is 12 h.

5. The method of claim 4, wherein the additive manufacturing of high strength-to- toughness heat resistant aluminum alloy material is characterized by: In S5, when the vacuum degree reaches below the preset vacuum degree, inert gas is introduced to atmospheric pressure, the inert gas is high-purity argon or nitrogen, the gas flow is controlled at 10-200 L / min, and the gas atomization pressure is 4-10 MPa. In S3 and S6, the ceramic reinforced aluminum matrix composite material powder is sieved after drying, and the average particle size of the aluminum matrix composite material powder is 15-53 μm. In S7, the energy density of the laser powder bed fusion technology is between 50 and 80 J / mm3, the laser power is between 190 and 350 W, and the scanning speed is between 1000 and 2000 mm / s; the oxygen content is controlled to be below 0.200%; the substrate temperature is set to 120-180 ℃, and the layer thickness is set to 20 μm-40 μm; 6. The method of claim 1, wherein the additive manufacturing high strength-to- toughness heat resistant aluminum alloy material is produced by, In S7, the conditions for solid solution aging heat treatment are as follows:

7. The method of claim 1, wherein the additive manufacturing of high strength-to- toughness heat resistant aluminum alloy material is characterized by, the aluminum alloy material solid solution temperature is 505-525 ℃; the solid solution time is 1.5-2.5 h; When the vacuum degree is lower than 10 -3 Pa, the preset temperature range is 800~1000℃; the aging temperature is 135-175 ℃; and the aging time is 4-6 h.

8. The method of claim 1, wherein the additive manufacturing high strength-to- toughness heat resistant aluminum alloy material is produced by, The additive manufactured high strength and toughness heat-resistant aluminum alloy material is prepared by the method for additive manufacturing high strength and toughness heat-resistant aluminum alloy material according to any one of claims 1-9.

9. The method of claim 1, wherein the additive manufacturing high strength-to- toughness heat resistant aluminum alloy material is produced by, ​ ​ ​ ​ ​ ​ 10. An additively manufactured high strength-to-toughness heat resistant aluminum alloy material, characterized in that, ​

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