Aluminum-lithium alloy material for laser additive manufacturing, preparation method and application thereof

Abstract

The application belongs to the technical field of laser additive manufacturing, and more particularly relates to an aluminum-lithium alloy material for laser additive manufacturing, a preparation method and application thereof. The aluminum-lithium alloy material comprises, in terms of mass percentage, 3.5-4.6% of Cu, 1-2% of Mg, 0.1-1.5% of Li, 0.1-1.2% of Sc, 0.1-1.2% of Zr, 0.1-1.2% of Y, and the rest is Al. The aluminum-lithium alloy material powder is formed by using a laser additive manufacturing technology and is directly subjected to aging heat treatment, so that an excellent structural part can be obtained, the cracking, high residual stress and anisotropy problems caused by a traditional aluminum-lithium alloy laser additive manufacturing method can be solved, and an aluminum-lithium alloy material part with excellent comprehensive mechanical properties and high lightweight is obtained.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, and more specifically, relates to an aluminum-lithium alloy material for laser additive manufacturing, its preparation method and application. Background Technology

[0002] Compared to traditional aluminum alloys, aluminum-lithium alloys possess lower density and higher specific strength and specific stiffness. Furthermore, they exhibit excellent low-temperature performance and corrosion resistance, leading to their widespread application in the aerospace field. As the requirements for components in high-end, large-scale equipment become increasingly demanding—requiring high degrees of freedom, lightweight construction, and greater complexity—traditional casting, forging, and welding methods are insufficient for component fabrication. Selective Laser Melting (SLM) technology, as one of the most widely used laser additive manufacturing methods, can integrally fabricate high-performance aluminum-lithium alloys with both complex shapes and high precision.

[0003] However, to date, there are not many scholars studying the preparation of aluminum-lithium alloys using laser additive manufacturing technology, and a complete material design and preparation system has not been formed. Moreover, the formed aluminum-lithium alloy components have common problems such as cracks and anisotropy. Due to the moving melting of the laser beam and the existence of a large temperature gradient in the molten pool, the molten pool undergoes rapid contraction during solidification, resulting in residual stress, which easily leads to crack formation. At the same time, columnar crystals have preferred orientation growth, and the component's microstructure and properties exhibit anisotropy.

[0004] Therefore, based on the above problems, there is an urgent need to design a new type of aluminum-lithium alloy material component and its preparation method that can improve the common problems of cracks, high residual stress and anisotropy generated by laser additive manufacturing.

[0005] Currently, Chinese invention patent document CN116287913 A discloses a trace element modified aluminum-lithium alloy powder for additive manufacturing and its preparation method. The method involves preparing aluminum-lithium alloy powder via electrode induction melting and vacuum atomization, followed by SLM forming. However, this method does not mention the loss and evaporation of metallic Mg and Li elements during powder preparation, which generates a large amount of smoke and dust, causing equipment malfunction and affecting the powder's preparation state and quality. Furthermore, due to the high temperature gradient in the molten pool during SLM forming, the aluminum-lithium alloy exhibits anisotropic microstructure and properties. Chinese invention patent document CN114082985 A discloses a Sc / Zr modified high-modulus, high-strength aluminum-lithium alloy and its laser forming method. This method involves gas atomization powder preparation of aluminum-lithium alloy and Sc / Zr ingots, significantly increasing alloy loss and production costs, while also resulting in high residual stress within the components. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide an aluminum-lithium alloy material for laser additive manufacturing, its preparation method and application, so as to solve the problems of cracking, high residual stress and anisotropy caused by the existing aluminum-lithium alloy laser additive manufacturing method, and obtain aluminum-lithium alloy material parts with excellent comprehensive mechanical properties that take into account both strength and plasticity and are highly lightweight.

[0007] To achieve the above objectives, the present invention provides an aluminum-lithium alloy material, the elemental composition of which, by mass percentage, comprises: 3.5-4.6% Cu, 1-2% Mg, 0.1-1.5% Li, 0.1-1.2% Sc, 0.1-1.2% Zr, 0.1-1.2% Y, with the remainder being Al.

[0008] Preferably, the aluminum-lithium alloy material comprises, by mass percentage: 4-4.3% Cu, 1.6-1.9% Mg, 0.8-1.2% Li, 0.8-1.2% Sc, 0.4-0.6% Zr, 0.1-0.4% Y, with the remainder being Al.

[0009] Preferably, the aluminum-lithium alloy material has the following impurity element content by mass percentage: O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%.

[0010] According to another aspect of the present invention, an aluminum-lithium alloy material component is provided, which is obtained by laser additive manufacturing of the aluminum-lithium alloy material.

[0011] According to another aspect of the present invention, a method for preparing the aluminum-lithium alloy material component is provided, comprising the following steps:

[0012] (1) The aluminum-lithium alloy material was melted by vacuum induction melting to obtain an alloy melt;

[0013] (2) The alloy melt described in step (1) is impacted and broken by an atomizing nozzle to atomize it into metal droplets. After the metal droplets solidify into metal powder, the metal powder is collected and sieved by a cyclone separation system to obtain aluminum-lithium alloy material powder for additive manufacturing.

[0014] (3) A three-dimensional model of the aluminum-lithium alloy material component is established and cut into a two-dimensional scanning trajectory using slicing software;

[0015] (4) Place the aluminum-lithium alloy material powder described in step (2) into the powder feeding chamber of the laser additive manufacturing equipment and preheat the substrate; form a three-dimensional aluminum-lithium alloy material preform layer by layer according to the two-dimensional scanning trajectory described in step (3);

[0016] (5) The aluminum-lithium alloy material preform is subjected to direct aging heat treatment to obtain the aluminum-lithium alloy material component.

[0017] Preferably, the vacuum induction melting in step (1) has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, and a melting temperature of 600-750℃.

[0018] Preferably, the pressure during atomization in step (2) is 1.8-2.9 MPa.

[0019] Preferably, the particle size range of the aluminum-lithium alloy material powder collected and sieved in step (2) is 15-54 μm.

[0020] Preferably, the laser power of the laser additive manufacturing in step (4) is 300-450W, the scanning rate is 1000-2600mm / s, the scanning spacing is 0.08-0.15mm, and the layer thickness is 0.03-0.06mm.

[0021] Preferably, the direct aging heat treatment temperature in step (5) is 100-400℃ and the time is 2-14 hours; more preferably, the direct aging heat treatment temperature is 150-250℃ and the time is 6-8 hours.

[0022] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0023] (1) The present invention provides an aluminum-lithium alloy material for laser additive manufacturing. By designing the types of powder components and controlling the content of the components to strengthen the forming components and the microstructure, the final product can obtain excellent tensile strength, yield strength, hardness and ductility. Among them, the addition of element Y can greatly improve the laser absorption rate of aluminum-lithium alloy powder. After the powder is melted by laser, the liquid pool can absorb higher laser energy. Under the same cooling rate, the higher laser absorption rate will lead to a higher temperature of the molten pool, thereby reducing the dynamic viscosity of the liquid metal in the molten pool and improving its fluidity. This can effectively suppress the generation of cracks and reduce thermal residual stress, greatly improve its performance, expand the laser additive manufacturing process window, and broaden its application range.

[0024] (2) This invention prepares a novel aluminum-lithium alloy powder and then uses laser additive manufacturing technology to form components. The nucleating agent elements Sc and Zr can form an Al3(Sc, Zr, Li) phase with Li. It has a highly similar crystal structure to the matrix and excellent matching degree. Compared with Al3Sc and Al3Zr, it has a lower lattice mismatch degree and melting point. During laser melting, the phase with the lower melting point melts preferentially and has a higher volume fraction. It can effectively fill intergranular cracks and reduce the tendency of solidification cracks. At the same time, the Al3(Sc, Zr, Li) phase solidifies and precipitates ahead of the matrix phase. As a grain refiner, it can increase the probability of columnar crystals transforming into equiaxed crystals and induce the nucleation of fine grains. It can also prevent thermal tearing during rapid solidification and greatly improve the performance of the components.

[0025] (3) The aluminum-lithium alloy material preparation method proposed in this invention can improve the common problems of cracking and high residual stress generated during laser additive manufacturing printing, reduce residual stress and maintain high precipitation strengthening effect; this invention proposes to solve the inherent problem of high residual stress in laser additive manufacturing by using direct aging heat treatment after obtaining the three-dimensional aluminum-lithium alloy material preform through laser additive manufacturing. During the laser additive manufacturing process, the laser melts and solidifies the alloy powder, which involves a high temperature gradient and an extremely high melting and cooling rate, resulting in high residual stress. At the same time, more alloy elements are dissolved in the matrix, causing lattice distortion, which greatly reduces the toughness and plasticity of the material, and makes it easy for the component to warp and crack in later processing. In the experiment of this invention, by comparing different heat treatment methods, it was found that compared with the traditional solution treatment + aging heat treatment process, the aluminum-lithium alloy material component prepared by the direct aging heat treatment method of this invention has significantly reduced residual stress and improved strength. A possible reason is that, given the specific elemental composition of the aluminum-lithium alloy produced by laser additive manufacturing in this invention, the component matrix already contains numerous supersaturated solid solutions (different elements have different solubilities; once a critical value is reached, the alloying element no longer dissolves in the matrix; simultaneously, the laser additive manufacturing process itself has an extremely fast cooling rate, resulting in non-equilibrium solidification and imparting uncontrollable supersaturated solid solutions to the matrix). Traditional heat treatment processes are no longer suitable. Traditional heat treatment processes, after solution treatment, generate strong grain boundary movement driving forces, leading to grain coarsening of fine equiaxed grains, making it difficult to resist crack initiation and stress concentration. However, experiments in this invention have shown that direct aging can avoid these problems. Direct aging heat treatment may allow different alloying elements to diffuse and migrate during the heat treatment process, and the cell boundaries will also migrate accordingly. Simultaneously, with the alloying elements... The precipitation of these substances forms numerous precipitates that, when distributed within the matrix, hinder dislocation movement, achieving a precipitation strengthening effect. During direct aging heat treatment, the relaxation of residual stress and changes in dislocation behavior significantly reduce the residual stress and improve the strength of the component. Specifically, the direct aging heat treatment of this invention increases the diffusion rate of atoms such as Sc, Zr, Li, Cu, and Mg, leading to increased precipitation of solute atoms and the generation of more Al2CuLi and Al2CuMg precipitates, exhibiting excellent precipitation strengthening effects. Furthermore, it can promote precipitation strengthening reactions by inhibiting dislocation movement, significantly improving mechanical strength. During direct aging heat treatment, the component achieves residual stress relaxation through internal local plastic deformation or local relaxation processes, thereby eliminating the problem of high residual stress in aluminum-lithium alloys.

[0026] (4) The aluminum-lithium alloy component of the present invention preheats the substrate during the printing process, reduces the extremely high temperature gradient inside the molten pool, slows down the difference in solidification rate in different areas of the molten pool, promotes the uniformity of solidification structure, and reduces the anisotropy of structure. Attached Figure Description

[0027] Figure 1This is an optical microscope image of an aluminum-lithium alloy powder laser additive manufacturing component according to Embodiment 1 of the present invention.

[0028] Figure 2 This is a scanning electron microscope image of the fracture morphology of the aluminum-lithium alloy powder laser additive manufacturing component of Embodiment 3 of the present invention.

[0029] Figure 3 This is a scanning electron microscope image of the fracture morphology of the aluminum-lithium alloy powder laser additive manufacturing component of Comparative Example 2 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] The present invention provides an aluminum-lithium alloy material, the elemental composition of which, by mass percentage, comprises: 3.5-4.6% Cu, 1-2% Mg, 0.1-1.5% Li, 0.1-1.2% Sc, 0.1-1.2% Zr, 0.1-1.2% Y, and the remainder Al. In a preferred embodiment, the elemental composition, by mass percentage, comprises: 4-4.3% Cu, 1.6-1.9% Mg, 0.8-1.2% Li, 0.8-1.2% Sc, 0.4-0.6% Zr, 0.1-0.4% Y, and the remainder Al.

[0032] In some embodiments, the impurity element content, by mass percentage, is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%.

[0033] This invention also provides an aluminum-lithium alloy material component, which can be obtained from the aforementioned aluminum-lithium alloy material via laser additive manufacturing. The preparation method of the aluminum-lithium alloy material component provided in some embodiments of this invention includes the following steps:

[0034] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0035] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: the powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. Specifically, a vacuum induction melting inert gas atomization device is first used to create a vacuum, then the raw materials are melted to obtain an alloy melt. The smoke generated by metal evaporation is then discharged through the smoke outlet. The alloy melt is then impacted and broken under high-pressure gas through an atomizing nozzle, atomizing it into fine metal droplets. Finally, the metal droplets solidify into metal powder, which is collected and sieved through a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. This powder preparation method can significantly reduce alloy burn-off. In some embodiments, the vacuum induction melting has a vacuum degree ≤ 0.03 Pa, a working oxygen content ≤ 500 ppm, and a melting temperature of 600-750 °C. The atomization pressure is 1.8-2.9 MPa.

[0036] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. The dried aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%.

[0037] Specifically, a first layer of powder is spread evenly on an alloy substrate using a powder spreading device. A high-energy laser beam is then used to print the first layer along a two-dimensional scanning trajectory. At the scanning location, the powder completely melts and rapidly solidifies into an alloy. The alloy substrate is then lowered to a certain height, and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder, and this process is repeated until the component is finally formed. Simultaneously, during the printing process, the melting temperature and speed can be changed by adjusting the laser process parameters and scanning strategy, thereby controlling the microstructure and properties during the forming process. In some embodiments, the laser power of the laser additive manufacturing is 300-450W, the scanning rate is 1000-2600mm / s, the scanning spacing is 0.08-0.15mm, and the layer thickness is 0.03-0.06mm.

[0038] (4) Direct aging heat treatment: The component is placed at a set temperature and held for a period of time to eliminate residual stress. During heat treatment, the residual stress in the component is relaxed through internal local plastic deformation or local relaxation processes, thereby achieving the purpose of elimination. In some embodiments, the direct aging heat treatment temperature is 100-400℃ and the time is 2-14 hours. In a preferred embodiment, the direct aging heat treatment temperature is 150-250℃ and the time is 6-8 hours.

[0039] This invention utilizes a three-dimensional model of the target component to form aluminum-lithium alloy powder into a material using laser additive manufacturing technology, followed by direct aging heat treatment to obtain excellent structural components. Through this invention, a novel aluminum-lithium alloy material specifically designed for laser additive manufacturing is developed, which solves the problems of cracking mechanisms, high residual stress, and anisotropy inherent in laser additive manufacturing methods for aluminum-lithium alloys, resulting in aluminum-lithium alloy material components with excellent comprehensive mechanical properties and high lightweight properties.

[0040] The following are specific examples:

[0041] Example 1

[0042] A novel aluminum-lithium alloy material component specifically for laser additive manufacturing and its preparation method, comprising the following steps:

[0043] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0044] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 32 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 3.75% Cu, 1.2% Mg, 0.5% Li, 0.4% Sc, 0.2% Zr, 0.1% Y, and the remainder is Al (Alloy 1). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt. Then, the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is impacted and broken under high pressure gas through an atomizing nozzle to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved through a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 675℃, and a pressure of 1.9MPa during atomization.

[0045] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. The first layer is printed by a high-energy laser beam according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. During the printing process, the laser power of laser additive manufacturing is 300W, the scanning rate is 1000mm / s, the scanning spacing is 0.08mm, and the layer thickness is 0.03mm.

[0046] (4) Direct aging heat treatment: The component is placed at 300℃ and kept at that temperature for 12 hours to eliminate residual stress. During heat treatment, the residual stress is relaxed through local plastic deformation or local relaxation process in the component, thereby achieving the purpose of elimination.

[0047] Figure 1 This is an optical microscope image of the aluminum-lithium alloy powder laser additive manufacturing component of this embodiment. The prepared component has no cracks and the molten pool boundary has a high grain boundary density.

[0048] Example 2

[0049] A novel aluminum-lithium alloy material component specifically for laser additive manufacturing and its preparation method, comprising the following steps:

[0050] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0051] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 28 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 4% Cu, 1.6% Mg, 0.75% Li, 0.7% Sc, 0.35% Zr, 0.2% Y, and the remainder is Al (Alloy 2). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt, and then the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is then impacted and broken by the atomizing nozzle under high pressure gas to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved through a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 700℃, and a pressure of 2.2MPa during atomization.

[0052] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. The first layer is printed by a high-energy laser beam according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. The laser power of laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0053] (4) Direct aging heat treatment: The component is placed at 240℃ and kept at that temperature for 10 hours to eliminate residual stress. During heat treatment, the residual stress in the component is relaxed through local plastic deformation or local relaxation process to achieve the purpose of elimination.

[0054] Example 3

[0055] A novel aluminum-lithium alloy material component specifically for laser additive manufacturing and its preparation method, comprising the following steps:

[0056] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0057] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. The aluminum-lithium alloy powder composition by mass fraction is: 4.15% Cu, 1.6% Mg, 1.2% Li, 0.8% Sc, 0.4% Zr, 0.3% Y (alloy 3), with the remainder being Al. First, a vacuum induction melting inert gas atomization device is used to create a vacuum. Then, the raw materials are melted to obtain an alloy melt. The smoke generated by metal evaporation is then discharged through the smoke outlet. The alloy melt is then impacted and broken under high-pressure gas through an atomizing nozzle, atomizing it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder. The metal powder is collected and sieved through a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 730℃, and a pressure of 2.6MPa during atomization.

[0058] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. The first layer is printed by a high-energy laser beam according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. The laser power of laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0059] (4) Direct aging heat treatment: The component is placed at 150℃ and kept at that temperature for 6 hours to eliminate residual stress. During heat treatment, the residual stress in the component is relaxed through local plastic deformation or local relaxation process to achieve the purpose of elimination.

[0060] Figure 2 The image shown is a scanning electron microscope image of the fracture morphology of the aluminum-lithium alloy powder laser additive manufacturing component in Example 3. It can be seen that there are many small and shallow dimples on the fracture surface. The dimples are evenly distributed, which proves that the aluminum-lithium alloy still maintains relatively good plasticity after direct aging.

[0061] Example 4

[0062] A novel aluminum-lithium alloy material component specifically for laser additive manufacturing and its preparation method, comprising the following steps:

[0063] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0064] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 4.15% Cu, 1.6% Mg, 1.2% Li, 0.8% Sc, 0.4% Zr, 0.3% Y, and the remainder is Al (Alloy 3). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt, and then the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is then impacted and broken by the atomizing nozzle under high pressure gas to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved by a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 730℃, and a pressure of 2.6MPa during atomization.

[0065] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. The first layer is printed by a high-energy laser beam according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. The laser power of laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0066] (4) Direct aging heat treatment: The component is placed at 250℃ for 6 hours to eliminate residual stress. During heat treatment, the residual stress is relaxed through local plastic deformation or local relaxation process to achieve the purpose of elimination.

[0067] Example 5

[0068] A novel aluminum-lithium alloy material component specifically for laser additive manufacturing and its preparation method, comprising the following steps:

[0069] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0070] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 4.15% Cu, 1.6% Mg, 1.2% Li, 0.8% Sc, 0.4% Zr, 0.3% Y, and the remainder is Al (Alloy 3). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt, and then the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is then impacted and broken by the atomizing nozzle under high pressure gas to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved by a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 730℃, and a pressure of 2.6MPa during atomization.

[0071] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to ensure that the oxygen content in the cavity is less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. A high-energy laser beam is used to print the first layer according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then, the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. At the same time, during the printing process, the melting temperature and speed can be changed by adjusting the laser process parameters and scanning strategy to control the microstructure and properties during the forming process. The laser power of the laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0072] (4) Direct aging heat treatment: The component is placed at 350℃ for 6 hours to eliminate residual stress. During heat treatment, the residual stress is relaxed through local plastic deformation or local relaxation process in the component, thereby achieving the purpose of elimination.

[0073] Comparative Example 1

[0074] An aluminum-lithium alloy material component and its preparation method, comprising the following steps:

[0075] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0076] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 4.15% Cu, 1.6% Mg, 1.2% Li, 0.8% Sc, 0.4% Zr, 0.3% Y, and the remainder is Al (Alloy 3). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt, and then the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is then impacted and broken by the atomizing nozzle under high pressure gas to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved by a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 730℃, and a pressure of 2.6MPa during atomization.

[0077] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to make the oxygen content in the cavity less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. The first layer is printed by a high-energy laser beam according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. The laser power of laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0078] Comparative Example 2

[0079] An aluminum-lithium alloy material component and its preparation method, comprising the following steps:

[0080] (1) Batching: Prepare intermediate alloy raw materials according to the weight percentage of each component element in the designed aluminum-lithium alloy composition.

[0081] (2) Preparation of a novel aluminum-lithium alloy powder specifically for laser additive manufacturing: The powder particle size ranges from 15 to 54 μm, and the impurity element content is O < 0.001%, C < 0.005%, S < 0.002%, and P < 0.002%. By mass fraction percentage, the aluminum-lithium alloy powder composition is: 4.15% Cu, 1.6% Mg, 1.2% Li, 0.8% Sc, 0.4% Zr, 0.3% Y, and the remainder is Al (Alloy 3). First, a vacuum induction melting inert gas atomization device is used to evacuate the vacuum, then the raw materials are melted to obtain an alloy melt, and then the smoke generated by metal evaporation is discharged through the smoke outlet. The alloy melt is then impacted and broken by the atomizing nozzle under high pressure gas to atomize it into fine metal droplets. Finally, the metal droplets are allowed to solidify into metal powder, which is then collected and sieved by a two-stage cyclone separation system to obtain powder particles suitable for laser additive manufacturing. The gas atomization process has a vacuum degree ≤0.03Pa, a working oxygen content ≤500ppm, a melting temperature of 730℃, and a pressure of 2.6MPa during atomization.

[0082] (3) Laser additive manufacturing: A three-dimensional model of the component is established, and the model is processed by slicing software to form a laser scanning trajectory. A dry aluminum-lithium alloy substrate is placed on the forming table of the printing equipment. Before forming, the substrate is preheated to 100°C to prevent cracking of the part during laser additive manufacturing and to reduce thermal residual stress in the component. A certain flow rate of high-purity argon gas (≥99.99%) is introduced in advance to ensure that the oxygen content in the cavity is less than 0.008%. Specifically, the first layer of powder is spread evenly on the alloy substrate by a powder spreading device. A high-energy laser beam is used to print the first layer according to the two-dimensional scanning trajectory. The powder at the scanning position is completely melted and quickly solidified into an alloy. Then, the alloy substrate is lowered to a certain height and powder is spread again. The laser scanning direction is rotated 67° to print the second layer. The laser beam melts the powder and this process is repeated until the component is finally formed. At the same time, during the printing process, the melting temperature and speed can be changed by adjusting the laser process parameters and scanning strategy to control the microstructure and properties during the forming process. The laser power of the laser additive manufacturing is 400W, the scanning rate is 1400mm / s, the scanning spacing is 0.12mm, and the layer thickness is 0.04mm.

[0083] (4) Solution aging heat treatment: The component is placed at 500℃ for 1 hour and then water quenched, and then aged at 150℃ for 6 hours.

[0084] Figure 3The image shown is a scanning electron microscope image of the fracture morphology of the aluminum-lithium alloy powder laser additive manufacturing component of Comparative Example 2 of this invention. It can be seen that compared with Example 3, there are a small number of microcracks and smooth tear surfaces on the fracture surface, which leads to a significant reduction in the plasticity of the component. After the aluminum-lithium alloy is subjected to solution aging treatment, the grain size is larger and coarsening occurs. During the tensile test, the stress concentration on the surface generates microcracks, which affects the plasticity of the component.

[0085] Mechanical tests were conducted on the components formed in Examples 1 to 5, Comparative Example 1, and Comparative Example 2. The four components were aluminum-lithium alloys obtained by different alloys or different heat treatment methods. The test method was ASTM E8 / E8M standard. The room temperature tensile properties of the standard tensile samples were tested using a C43.104 30kN high temperature electronic universal testing machine manufactured by Shanghai Xin Sansi. The test speed was 1.0 mm / min. The test results are shown in Table 1.

[0086] Table 1 Test Results

[0087]

[0088] As can be seen from the experimental results in Table 1, the aluminum-lithium alloy of Comparative Example 1 exhibits relatively ideal mechanical properties after laser additive manufacturing without any heat treatment. However, aluminum-lithium alloy components require high strength for application. For non-additively manufactured aluminum-lithium alloy components, the traditional method generally uses solution treatment followed by aging heat treatment to improve their strength, i.e., the heat treatment method of Comparative Example 2 is adopted. However, when this heat treatment method is used on alloy 3 in the present invention, it can be seen that the strength of the alloy component is significantly improved, but the plasticity decreases too much, from 12.9% to 3.4%. The poor plasticity makes it unwearable and lacks resistance to deformation in practical applications.

[0089] One of the key technical problems this invention aims to solve is how to improve strength while maintaining good plasticity. In Examples 1 to 5 of this invention, direct aging heat treatment ideally improves the strength of the components while maintaining a low reduction in plasticity. In particular, the examples demonstrate that direct aging heat treatment can produce precipitation strengthening and eliminate residual stress, while simultaneously inhibiting the initiation and propagation of microcracks during tensile deformation. Comparing alloy 3 with the same alloy composition, as the aging temperature increases, the content and types of precipitated phases increase, contributing more to the strength improvement. Direct aging heat treatment inhibits a significant reduction in the plasticity of the components, making it a relatively ideal heat treatment method for the aluminum-lithium alloy components manufactured by additive manufacturing in this invention.

[0090] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An aluminum-lithium alloy material component, characterized in that, It is obtained by laser additive manufacturing of aluminum-lithium alloy material; The elemental composition of the aluminum-lithium alloy material, by mass percentage, includes: 3.5-4.6% Cu, 1-2% Mg, 0.1-1.5% Li, 0.1-1.2% Sc, 0.1-1.2% Zr, 0.1-1.2% Y, with the remainder being Al; When preparing the aluminum-lithium alloy material component, after obtaining the three-dimensional aluminum-lithium alloy material preform by laser additive manufacturing, direct aging heat treatment is used to solve the common problem of high residual stress inherent in laser additive manufacturing.

2. The aluminum-lithium alloy material component as described in claim 1, characterized in that, Its elemental composition, by mass percentage, includes: 4-4.3% Cu, 1.6-1.9% Mg, 0.8-1.2% Li, 0.8-1.2% Sc, 0.4-0.6% Zr, 0.1-0.4% Y, with the remainder being Al.

3. The aluminum-lithium alloy material component as described in claim 1, characterized in that, By mass percentage, the impurity element content is O<0.001%, C<0.005%, S<0.002%, and P<0.002%.

4. The method for preparing aluminum-lithium alloy material components according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The aluminum-lithium alloy material was melted by vacuum induction melting to obtain an alloy melt; (2) The alloy melt described in step (1) is impacted and broken through an atomizing nozzle to atomize it into metal droplets. After the metal droplets solidify into metal powder, the metal powder is collected and sieved through a cyclone separation system to obtain aluminum-lithium alloy material powder for additive manufacturing. (3) A three-dimensional model of the aluminum-lithium alloy material component is established and cut into a two-dimensional scanning trajectory using slicing software; (4) Place the aluminum-lithium alloy material powder described in step (2) into the powder feeding chamber of the laser additive manufacturing equipment and preheat the substrate; form the three-dimensional aluminum-lithium alloy material preform layer by layer according to the two-dimensional scanning trajectory described in step (3); (5) The aluminum-lithium alloy material preform is subjected to direct aging heat treatment to obtain the aluminum-lithium alloy material component.

5. The preparation method according to claim 4, characterized in that, The vacuum induction melting in step (1) has a vacuum degree ≤0.03 Pa, a working oxygen content ≤500 ppm, and a melting temperature of 600-750℃.

6. The preparation method according to claim 4, characterized in that, The pressure during atomization in step (2) is 1.8-2.9 MPa.

7. The preparation method according to claim 4, characterized in that, The particle size range of the aluminum-lithium alloy material powder collected and sieved in step (2) is 15-54 μm.

8. The preparation method according to claim 4, characterized in that, The laser power of the laser additive manufacturing in step (4) is 300-450W, the scanning rate is 1000-2600mm / s, the scanning spacing is 0.08-0.15 mm, and the layer thickness is 0.03-0.06 mm.

9. The preparation method according to claim 4, characterized in that, The direct aging heat treatment in step (5) is performed at a temperature of 100-400℃ for 2-14 hours.

10. The preparation method according to claim 4, characterized in that, The direct aging heat treatment in step (5) is performed at a temperature of 150-250℃ for 6-8 hours.

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