Graphene modified 3D printing high-strength aluminum alloy and preparation method thereof

Abstract

The invention discloses a graphene modified 3D printing high-strength aluminum alloy and a preparation method thereof, and belongs to the technical field of metal additive manufacturing materials. The method comprises the following steps: carrying out gas atomization powder preparation on a high-strength aluminum alloy master alloy ingot or a high-strength heat-resistant aluminum alloy master alloy ingot to respectively obtain aluminum alloy powder; then, uniformly dispersing a liquid phase of graphene aluminum alloy powder into the aluminum alloy powder; and finally, molding the 3D printing aluminum alloy powder. Graphene is uniformly dispersed in aluminum alloy powder, so that the forming difficulty is reduced. Meanwhile, graphene and Ti element are subjected to in-situ reaction, a nano TiC phase is generated in situ in the additive manufacturing process, heterogeneous nucleation is promoted, grain refinement and structure uniformity are promoted, meanwhile, part of graphene is reserved to achieve a load transfer effect, internal stress in the thermal cycle process is reduced, stress concentration is relieved, and hot cracks are reduced. In addition, under the combined action of grain refinement, TiC phase and graphene, the obdurability of the material is improved, the hot crack sensitivity is reduced, and meanwhile, the room-temperature and high-temperature strength and plasticity of the alloy are improved.

Description

Technical Field

[0001] This invention relates to a graphene-modified 3D-printed high-strength aluminum alloy and its preparation method, belonging to the field of metal additive manufacturing materials technology. Background Technology

[0002] Metal additive manufacturing (3D printing) is a technology that uses powdered metal or plastic and other bondable materials to stack and print components layer by layer based on a computer-generated three-dimensional model. Compared with traditional manufacturing processes, additive manufacturing technology has advantages such as the ability to form complex components and savings in raw materials and time costs. Selective laser melting (SLM) is one of the most widely used technologies in metal additive manufacturing. With the increasing demand for lightweighting in various fields, additively manufactured aluminum alloys are widely used in aerospace, shipbuilding, and transportation due to their low density, high specific strength, corrosion resistance, and good electrical and thermal conductivity.

[0003] Currently, the most widely used aluminum alloys for 3D printing are still Al-Si alloys. Due to their good casting properties and narrow solidification range, they exhibit good forming performance in the 3D printing field. However, their poor room temperature and high temperature mechanical properties limit their application. Traditional high-strength / heat-resistant aluminum alloys (such as Al7075 and Al2024) are prone to hot cracking during 3D printing due to their wide solidification temperature range and poor weldability, leading to part failure. Existing technologies mainly suppress hot cracking through the following methods: 1. Alloying modification: Adding elements such as Ti, Zr, and Sc, or ceramic particles (such as TiB2 and TiC) to refine grains and reduce solidification stress. 2. Process optimization: Adjusting laser parameters (power, scanning speed) or adopting interlayer pause strategies to control the thermal history of the molten pool and reduce residual stress. However, traditional methods suffer from high costs (e.g., expensive Sc), complex processes (e.g., harsh in-situ reaction conditions), or loss of ductility. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention proposes a graphene-modified 3D-printed high-strength aluminum alloy and its preparation method.

[0005] A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) High-strength aluminum alloy master alloy ingots or high-strength heat-resistant aluminum alloy master alloy ingots are subjected to gas atomization to obtain high-strength aluminum alloy powder or high-strength heat-resistant aluminum alloy powder: (2) Graphene is dispersed in ethanol, and then high-strength aluminum alloy powder or high-strength heat-resistant aluminum alloy powder is added and stirred. Finally, the powder is dried to obtain graphene / aluminum alloy composite material powder. (3) Using graphene / aluminum alloy composite powder for laser additive manufacturing to obtain Ti-graphene modified 3D printed high-strength aluminum alloy; The high-strength aluminum alloy master alloy ingot comprises the following alloying elements by mass percentage: Zn ≤ 10 wt.%, Mg: 0.2-1.8 wt.%, Cu ≤ 5 wt.%, Mn: 0.2-0.8 wt.%, Ti: 0.15-0.5 wt.%, Si: ≤ 1.0 wt.%, Zr ≤ 0.2 wt.%, Cr ≤ 0.3 wt.%, with the balance being Al and unavoidable impurities; The high-strength heat-resistant aluminum alloy master alloy ingot comprises the following alloying elements by mass percentage: Fe: 3.2-6.5 wt.%, Cr: 2.5-3.5 wt.%, Ti: 2.5-4.0 wt.%, with the balance being Al and unavoidable impurities.

[0006] As a preferred embodiment of the present invention, in step (1), the gas atomization powder production parameters include: the gas atomization powder production is carried out under an inert protective atmosphere, the gas atomization powder production temperature is 700-850℃, the gas atomization powder production pressure is 2.4-3.8MPa, and the pressure of the inert protective atmosphere is 0.1-0.12MPa.

[0007] As a preferred embodiment of the present invention, in step (2), the graphene mass fraction in the graphene / aluminum alloy composite powder is 0.05-1.0wt%.

[0008] In a preferred embodiment of the present invention, the graphene is graphene nanosheet or graphene oxide, the number of graphene layers is ≤30, and the lateral dimension is ≤10μm.

[0009] As a preferred embodiment of the present invention, the process parameters of the laser additive manufacturing are: laser power of 350-400W, scanning speed of 1000-1500mm / s, layer thickness of 20-40μm, and scanning spacing of 0.10-0.15mm.

[0010] The present invention also claims protection for the method for preparing the graphene-modified 3D-printed high-strength aluminum alloy.

[0011] The beneficial effects of this invention are as follows: By uniformly dispersing graphene in aluminum alloy powder, this invention utilizes the high laser absorption rate of graphene to further expand the processing window of selective laser melting, reducing the difficulty of forming. Simultaneously, the in-situ reaction between graphene and Ti elements generates nano-TiC phases during additive manufacturing, promoting heterogeneous nucleation, resulting in grain refinement and a more uniform microstructure. Furthermore, the retention of some graphene can play a role in load transfer, reducing internal stress during thermal cycling, alleviating stress concentration, and thus significantly reducing hot cracking. In addition, the combined effect of grain refinement, the TiC phase, and graphene can improve the strength and toughness of the material. The coupling effect of Ti and graphene reduces the hot cracking sensitivity to 1 / 5-1 / 10 of traditional methods, while improving the room temperature and high temperature strength and plasticity of the alloy. The Ti-graphene modified 3D printing high-strength aluminum alloy prepared by this invention is suitable for applications requiring high-strength and tough materials, such as lightweight aerospace components (e.g., aircraft frames, rocket fuel tanks) and structural components for new energy vehicles. Attached Figure Description

[0012] Figure 1 The appearance morphology of the graphene / aluminum alloy composite powder prepared in Examples 1 and 2 are as follows: (a) graphene / aluminum alloy composite powder prepared in Example 1; (b) graphene / aluminum alloy composite powder prepared in Example 2; (c) magnified EDS spectrum of graphene / aluminum alloy composite powder prepared in Example 1.

[0013] Figure 2 Macroscopic morphology of the 3D-printed high-strength aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-4: (a) 3D-printed high-strength aluminum alloy prepared in Example 1; (b) 3D-printed high-strength aluminum alloy prepared in Example 2; (c) 3D-printed high-strength aluminum alloy prepared in Example 3; (d) 3D-printed high-strength aluminum alloy prepared in Comparative Example 1; (e) 3D-printed high-strength aluminum alloy prepared in Comparative Example 2; (f) 3D-printed high-strength aluminum alloy prepared in Comparative Example 3; (g) 3D-printed high-strength aluminum alloy prepared in Comparative Example 4.

[0014] Figure 3 Optical microscope images of the 3D-printed high-strength aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-4: (a) 3D-printed high-strength aluminum alloy prepared in Example 1; (b) 3D-printed high-strength aluminum alloy prepared in Example 2; (c) 3D-printed high-strength aluminum alloy prepared in Example 3; (d) 3D-printed high-strength aluminum alloy prepared in Comparative Example 1; (e) 3D-printed high-strength aluminum alloy prepared in Comparative Example 2; (f) 3D-printed high-strength aluminum alloy prepared in Comparative Example 3; (g) 3D-printed high-strength aluminum alloy prepared in Comparative Example 4.

[0015] Figure 4This is a TEM microstructure image of the 3D-printed high-strength aluminum alloy prepared in Example 1. Detailed Implementation

[0016] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0017] Example 1 A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) High-strength aluminum alloy master alloy ingots are smelted and cast according to the formula. Pure Al, Al-Fe master alloy, Al-Cr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The master alloy ingots include the following alloy elements in mass percentage: Fe: 3.75wt.%, Cr: 3.23wt.%, Ti: 3.25wt.%, with the balance being Al and unavoidable impurities; the mass fraction of Ti element is 3.25wt.%.

[0018] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The gas atomization powder preparation was carried out under an inert protective atmosphere at a temperature of 840℃, a pressure of 2.7 MPa, and a pressure of 0.1 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0019] (3) The selected graphene has 20 layers and a lateral dimension of 5 μm. First, 25 g of graphene was sonicated in 1000 ml of anhydrous ethanol for 45 minutes. Then, the 3D printing powder prepared in step (2) was added and magnetically stirred so that the mass fraction of graphene in the total amount of 3D printing powder and graphene was 0.5 wt%. The magnetic stirring speed was 420 rpm and the stirring time was set to 35 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 20 h to obtain graphene / aluminum alloy composite powder.

[0020] (4) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 370W, scanning speed 1350mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 99.7% was obtained, and the printed aluminum alloy was obtained. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0021] Example 2 A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) Smelt and cast high-strength aluminum alloy master alloy ingots according to the formula. Pure Al, pure Zn, pure Mg, Al-Cu master alloy, Al-Si master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Zr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The high-strength aluminum alloy matrix includes the following alloying elements by mass percentage: Zn: 6.7wt.%, Mg: 1.4wt.%, Cu: 1.5wt.%, Ti: 0.45wt.%, Si: 0.5wt.%, Mn: 0.3wt.%, Cr: 0.15wt.%, Zr: 0.1wt.%, with the balance being Al and unavoidable impurities.

[0022] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The process was conducted in an inert protective atmosphere, with a gas atomization powder preparation temperature of 820℃, a gas atomization powder preparation pressure of 3.2 MPa, and an inert protective atmosphere pressure of 0.12 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0023] (3) The selected graphene has 20 layers and a lateral dimension of 5 μm. First, 20 g of graphene was ultrasonically dissolved in 1000 ml of anhydrous ethanol for 50 minutes. Then, 3D printing powder was added and magnetically stirred to make the mass fraction of graphene in the total amount of 3D printing powder and graphene 0.5 wt%. The magnetic stirring speed was 450 rpm and the stirring time was set to 40 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 18 h to obtain graphene / aluminum alloy composite powder.

[0024] (4) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 360W, scanning speed 1200mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 99.6% was obtained, and the printed aluminum alloy was obtained. Then, T6 heat treatment was performed. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0025] Example 3 A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) High-strength aluminum alloy master alloy ingots are smelted and cast according to the formula. Pure Al, pure Mg, Al-Cu master alloy, Al-Si master alloy, Al-Mn master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. Among them, the high-strength aluminum alloy powder matrix includes the following alloying elements by mass percentage: Cu: 4.1wt.%, Mg: 1.5wt.%, Mn: 0.7wt.%, Ti: 0.4wt.%, Si: 0.4wt.%, with the balance being Al and unavoidable impurities.

[0026] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The process was conducted in an inert protective atmosphere, with a gas atomization powder preparation temperature of 810℃, a gas atomization powder preparation pressure of 3.2 MPa, and an inert protective atmosphere pressure of 0.12 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0027] (3) The selected graphene has 15 layers and a lateral dimension of 5 μm. First, 25 g of graphene was sonicated in 1000 ml of anhydrous ethanol for 45 minutes. Then, 3D printing powder was added and magnetically stirred to make the mass fraction of graphene in the total amount of 3D printing powder and graphene 0.5 wt%. The magnetic stirring speed was 450 rpm and the stirring time was set to 35 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 20 h to obtain graphene / aluminum alloy composite powder.

[0028] (4) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 380W, scanning speed 1300mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 99.4% was obtained, and the printed aluminum alloy was obtained. Then, T6 heat treatment was performed. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal testing machine. The results are shown in Table 1.

[0029] Example 4 A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) Smelt and cast high-strength aluminum alloy master alloy ingots according to the formula. Pure Al, Al-Fe master alloy, Al-Cr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The master alloy ingots include the following alloy elements by mass percentage: Fe: 6.5wt.%, Cr: 2.56wt.%, Ti: 2.5wt.%, with the balance being Al and unavoidable impurities.

[0030] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The process was conducted in an inert protective atmosphere, with a gas atomization powder preparation temperature of 700℃, a gas atomization powder preparation pressure of 3.8MPa, and an inert protective atmosphere pressure of 0.1MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0031] (3) The selected graphene has 30 layers and a lateral dimension of 10 μm. First, 25 g of graphene was sonicated in 1000 ml of anhydrous ethanol for 45 minutes. Then, the 3D printing powder prepared in step (2) was added and magnetically stirred so that the mass fraction of graphene in the total amount of 3D printing powder and graphene was 0.05 wt%. The magnetic stirring speed was 420 rpm and the stirring time was set to 35 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 20 h to obtain graphene / aluminum alloy composite powder.

[0032] (4) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 400W, scanning speed 1500mm / s, layer thickness 20μm, and scanning spacing 0.15mm. By optimizing the parameters, a metal block with a density of 99.2% was obtained, and the printed aluminum alloy was obtained. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal testing machine. The results are shown in Table 1.

[0033] Example 5 A method for preparing graphene-modified 3D-printed high-strength aluminum alloy includes the following steps: (1) Smelt and cast high-strength aluminum alloy master alloy ingots according to the formula. Pure Al, pure Zn, pure Mg, Al-Cu master alloy, Al-Si master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Zr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The high-strength aluminum alloy matrix includes the following alloying elements by mass percentage: Zn: 10wt.%, Mg: 0.8wt.%, Cu: 5wt.%, Ti: 0.15wt.%, Si: 1.0wt.%, Mn: 0.8wt.%, Cr: 0.3wt.%, Zr: 0.2wt.%, with the balance being Al and unavoidable impurities.

[0034] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The process was conducted in an inert protective atmosphere, with a gas atomization powder preparation temperature of 850℃, a gas atomization powder preparation pressure of 2.4 MPa, and an inert protective atmosphere pressure of 0.11 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0035] (3) The selected graphene has 20 layers and a lateral dimension of 5 μm. First, 20 g of graphene was ultrasonically dissolved in 1000 ml of anhydrous ethanol for 50 minutes. Then, 3D printing powder was added and magnetically stirred to make the mass fraction of graphene in the total amount of 3D printing powder and graphene 1.0 wt%. The magnetic stirring speed was 450 rpm and the stirring time was set to 40 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 18 h to obtain graphene / aluminum alloy composite powder.

[0036] (4) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 350W, scanning speed 1000mm / s, layer thickness 40μm, and scanning spacing 0.12mm. By optimizing the parameters, a metal block with a density of 99.2% was obtained, and the printed aluminum alloy was obtained. Then, T6 heat treatment was performed. The room temperature tensile properties and high temperature mechanical properties at 350℃ of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0037] Comparative Example 1 A method for preparing high-strength aluminum alloy for 3D printing includes the following steps: (1) High-strength aluminum alloy master alloy ingots are smelted and cast according to the formula. Pure Al, Al-Fe master alloy, Al-Cr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The master alloy ingots include the following alloy elements in mass percentage: Fe: 3.75wt.%, Cr: 3.23wt.%, Ti: 3.25wt.%, with the balance being Al and unavoidable impurities; the mass fraction of Ti element is 3.25wt.%.

[0038] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The gas atomization powder preparation was carried out under an inert protective atmosphere at a temperature of 840℃, a pressure of 2.7 MPa, and a pressure of 0.1 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0039] (2) The powder for 3D printing was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 370W, scanning speed 1350mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 91.7% was obtained, and a printed aluminum alloy was obtained. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0040] Comparative Example 2 A method for preparing high-strength aluminum alloy for 3D printing includes the following steps: (1) Smelting and casting high-strength aluminum alloy master alloy ingots according to the formula. Pure Al, pure Zn, pure Mg, Al-Cu master alloy, Al-Si master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Zr master alloy and Al-Ti master alloy are smelted and cast according to the formula to obtain master alloy ingots. The high-strength aluminum alloy matrix includes the following alloying elements in the following mass percentages: Zn: 6.7wt.%, Mg: 1.4wt.%, Cu: 1.5wt.%, Ti: 0.75wt.%, Si: 0.5wt.%, Mn: 0.3wt.%, Cr: 0.15wt.%, Zr: 0.1wt.%, with the balance being Al and unavoidable impurities.

[0041] (2) Subsequently, gas atomization powder preparation was carried out under argon protection. The gas atomization powder preparation was carried out under an inert protective atmosphere at a temperature of 830°C, a pressure of 2.7 MPa, and a pressure of 0.1 MPa. The prepared powder was then sieved to obtain powder for 3D printing.

[0042] (3) High-strength aluminum alloy powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 380W, scanning speed 1050mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 92.9% was obtained, and the printed aluminum alloy was obtained. Then, T6 heat treatment was performed. The room temperature tensile properties and high temperature mechanical properties at 350℃ of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0043] Comparative Example 3 A method for preparing high-strength aluminum alloy for 3D printing includes the following steps: (1) High-strength aluminum alloy master alloy ingots are smelted and cast according to the formula. Pure Al, pure Mg, Al-Cu master alloy, Al-Si master alloy and Al-Mn master alloy are smelted and cast according to the formula to obtain master alloy ingots. Among them, the high-strength aluminum alloy powder matrix includes the following alloying elements by mass percentage: Cu: 4.1wt.%, Mg: 1.5wt.%, Mn: 0.7wt.%, Si: 0.4wt.%, with the balance being Al and unavoidable impurities.

[0044] (2) Subsequently, gas atomization powder preparation was carried out under argon protection and in an inert protective atmosphere. The gas atomization powder preparation temperature was 815℃, the gas atomization powder preparation pressure was 3.0MPa, and the pressure of the inert protective atmosphere was 0.12MPa. The obtained powder was then sieved to finally obtain powder for 3D printing.

[0045] (2) The selected graphene has 15 layers and a lateral dimension of 5 μm. First, 25 g of graphene was sonicated in 1000 ml of anhydrous ethanol for 45 minutes. Then, 3D printing powder was added and magnetically stirred to make the mass fraction of graphene in the total amount of 3D printing powder and graphene 0.1 wt%. The magnetic stirring speed was 420 rpm and the stirring time was set to 35 minutes to obtain uniformly dispersed powder. Then, the powder was vacuum dried at 90 °C for 20 h to obtain graphene / aluminum alloy composite powder.

[0046] (3) The graphene / aluminum alloy composite powder was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 380W, scanning speed 1300mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 95.9% was obtained, and the printed aluminum alloy was obtained. Then, T6 heat treatment was performed. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0047] Comparative Example 4 A method for preparing high-strength aluminum alloy for 3D printing includes the following steps: (1) Smelt and cast high-strength aluminum alloy master alloy ingots according to the formula. Pure Al, Al-Fe master alloy and Al-Cr master alloy are smelted and cast according to the formula to obtain master alloy ingots. The high-strength aluminum alloy matrix includes the following alloying elements by mass percentage: Fe: 3.75wt.%, Cr: 3.23wt.%, with the balance being Al and unavoidable impurities.

[0048] (2) Subsequently, gas atomization powder preparation was carried out under argon protection and in an inert protective atmosphere. The gas atomization powder preparation temperature was 840℃, the gas atomization powder preparation pressure was 2.7 MPa, and the pressure of the inert protective atmosphere was 0.1 MPa. The obtained powder was then sieved to finally obtain powder for 3D printing.

[0049] (2) The powder for 3D printing was prepared by selective laser melting additive manufacturing process. The process parameters of selective laser melting additive manufacturing process were: laser power 370W, scanning speed 1350mm / s, layer thickness 30μm, and scanning spacing 0.1mm. By optimizing the parameters, a metal block with a density of 91.1% was obtained, and a printed aluminum alloy was obtained. The room temperature tensile and high temperature mechanical properties of the printed alloy were tested by a universal mechanical testing machine. The results are shown in Table 1.

[0050] Table 1 Mechanical properties at room temperature and 350℃ like Figure 1As shown in Examples 1 and 2 of the present invention, graphene was well dispersed in aluminum alloy powder, and there was no obvious agglomeration of graphene. At the same time, the presence of graphene was confirmed by EDS energy dispersive spectroscopy.

[0051] contrast Figure 2 and Figure 3 It can be seen that the graphene-modified 3D-printed high-strength aluminum alloys prepared in Examples 1-3 all exhibited good forming performance, and no obvious cracks were observed through macroscopic observation; while Comparative Examples 1-4 all showed varying degrees of interlayer cracking and warping. Further analysis using a microscopic microscope showed that Examples 1-3 had no obvious pores or cracks; while Comparative Examples 1-4 all showed varying degrees of pores and crack defects.

[0052] Analysis of Table 1 shows that the graphene-modified 3D-printed high-strength aluminum alloys prepared in Examples 1-3 exhibit good room-temperature strength and ductility. Comparative Examples 1-2, due to interlaminar cracking, have low density, leading to early failure in the initial tensile stage because the cracks cannot withstand the stress, resulting in low fracture elongation and brittle fracture. Comparative Example 3 shows that while introducing graphene without Ti improves the alloy's hot-cracking tendency to some extent, its elongation remains low, and its room-temperature and high-temperature performance is significantly lower than that of Example 3, failing to meet long-term service requirements. Comparative Example 4 shows that the sample without Ti and graphene cannot achieve good high-temperature performance, exhibiting a significant decrease in high-temperature performance, and its low density also results in brittle fracture.

[0053] pass Figure 4 Microstructure analysis of Example 1 revealed that, based on the synergistic reaction of graphene / Ti, during selective laser melting, the instantaneous high temperature, under the interaction of the laser and aluminum alloy powder, forms a molten pool that rapidly melts the powder. As the laser leaves the molten pool, rapid solidification occurs. During this process, graphene preferentially reacts with Ti to generate nano-TiC second phase in situ. These nano-TiC second phases partially serve as effective heterogeneous nucleation sites for grains, effectively alleviating stress concentration while refining the grains. Simultaneously, some TiC phases can act as nucleation sites for the second phase, refining and uniformly distributing the second phase, eliminating large-sized second phases, and achieving a uniform microstructure. This, in turn, inhibits the initiation of thermal cracks during printing and molding, resulting in a high density of the component.

[0054] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing graphene-modified 3D-printed high-strength aluminum alloy, characterized in that: Includes the following steps: (1) High-strength aluminum alloy master alloy ingots or high-strength heat-resistant aluminum alloy master alloy ingots are subjected to gas atomization to obtain high-strength aluminum alloy powder or high-strength heat-resistant aluminum alloy powder: (2) Graphene is dispersed in ethanol, and then high-strength aluminum alloy powder or high-strength heat-resistant aluminum alloy powder is added and stirred. Finally, the powder is dried to obtain graphene / aluminum alloy composite material powder. (3) Graphene / aluminum alloy composite powder was used in laser additive manufacturing to obtain graphene-modified 3D printed high-strength aluminum alloy; The high-strength aluminum alloy master alloy ingot comprises the following alloying elements by mass percentage: Zn ≤ 10 wt.%, Mg: 0.2-1.8 wt.%, Cu ≤ 5 wt.%, Mn: 0.2-0.8 wt.%, Ti: 0.15-0.5 wt.%, Si: ≤ 1.0 wt.%, Zr ≤ 0.2 wt.%, Cr ≤ 0.3 wt.%, with the balance being Al and unavoidable impurities; The high-strength heat-resistant aluminum alloy master alloy ingot comprises the following alloying elements by mass percentage: Fe: 3.2-6.5 wt.%, Cr: 2.5-3.5 wt.%, Ti: 2.5-4.0 wt.%, with the balance being Al and unavoidable impurities.

2. The method for preparing graphene-modified 3D-printed high-strength aluminum alloy according to claim 1, characterized in that: In step (1), the parameters for gas atomization powder production include: the gas atomization powder production is carried out under an inert protective atmosphere, the gas atomization powder production temperature is 700-850℃, the gas atomization powder production pressure is 2.4-3.8MPa, and the pressure of the inert protective atmosphere is 0.1-0.12MPa.

3. The method for preparing graphene-modified 3D-printed high-strength aluminum alloy according to claim 1, characterized in that: In step (2), the graphene mass fraction in the graphene / aluminum alloy composite powder is 0.05-1.0 wt%.

4. The method for preparing graphene-modified 3D-printed high-strength aluminum alloy according to claim 1, characterized in that: The number of graphene layers is ≤30, and the lateral dimension is ≤10μm.

5. The method for preparing graphene-modified 3D-printed high-strength aluminum alloy according to claim 1, characterized in that: The process parameters for laser additive manufacturing are as follows: laser power of 350-400W, scanning speed of 1000-1500mm / s, layer thickness of 20-40μm, and scanning spacing of 0.10-0.15mm.

6. A graphene-modified 3D-printed high-strength aluminum alloy prepared by the method described in any one of claims 1-5.

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