Preparation method of high-strength and tough nano-TiB2 reinforced aluminum-lithium based composite material

Abstract

This invention discloses a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material, comprising the following steps: S1, preparing a precast ingot of nano-TiB2 / Al composite particles; S2, placing the aluminum-lithium-based composite material raw material in a low-vacuum stirring melting furnace for melting; S3, adding pure Li particles and a commercially available aluminum-lithium alloy covering agent to the molten aluminum-lithium-based composite material raw material; S4, then adding the precast ingot of nano-TiB2 / Al composite particles to the molten aluminum-lithium-based composite material raw material and stirring the molten aluminum-lithium-based composite material raw material; S5, pouring the aluminum-lithium alloy melt containing nanoparticles into a mold and subjecting it to ultrasonic vibration, and then evacuating the mold cavity to obtain a nanoparticle-reinforced cast aluminum-lithium alloy. This method has higher operability and can effectively suppress the serious problems of hydrogen absorption and oxidation caused by prolonged contact with air in aluminum-lithium alloys, and the nanoparticles are uniformly distributed in the alloy.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material, belonging to the field of metallurgy and casting technology. Background Technology

[0002] Nano-ceramic particle-reinforced aluminum matrix composites have broad application prospects due to their numerous advantages, including high specific strength and specific stiffness, good wear resistance, high thermal conductivity, and low coefficient of thermal expansion. Aluminum-lithium alloys, as a novel aerospace structural material, offer advantages such as low density, high specific strength, and specific stiffness. Replacing traditional commercial aluminum alloys with these alloys can significantly improve structural stability, reduce the weight of structural components by 10%–20%, and increase stiffness by 15%–20%. Therefore, in-depth research and preparation of nano-ceramic particle-reinforced aluminum-lithium matrix composites using aluminum-lithium alloys is of great significance and practical application value.

[0003] However, unlike other aluminum alloys, lithium (Li) is highly chemically reactive and readily reacts with air during the smelting of aluminum-lithium alloys, leading to oxidation and hydrogen absorption problems. These problems become more pronounced with increasing Li content in the alloy. Therefore, the preparation of aluminum-lithium-based composite materials is extremely difficult, severely hindering their further application. Chinese patent application CN108998700 A discloses an ultralightweight, high-modulus, high-strength cast aluminum-lithium-based composite material and its preparation method. In this patent, the Li content in the matrix alloy can reach as high as 3.5 wt.%, but the resulting T6-state in-situ self-generated TiB2-reinforced aluminum-lithium-based composite material generally has a low elongation (around 2%). Meanwhile, Chinese patent application CN115652149 A discloses a lightweight, high-strength aluminum-lithium-based composite material containing TiB2-reinforcing particles and its preparation method. Extruded bars are obtained through homogenization annealing and hot extrusion processes, followed by solution treatment and aging to obtain the desired material. However, the elongation of the composite material is only around 4%.

[0004] Although in-situ reaction synthesis can produce ceramic particle-reinforced aluminum-lithium-based composites, the in-situ generation of TiB2 particles is unfortunately hampered by excessively high reaction temperatures (above 800ºC) and difficulty in process control. Typically, TiB2 particles are submicron in size, leading to severe gas absorption, oxidation, and significant particle agglomeration, particularly at grain boundaries. This results in poor strength and toughness of the composite material, especially its extremely poor plasticity. Therefore, it is necessary to provide a more operable preparation method that can rapidly add nanoparticles while effectively suppressing the severe hydrogen absorption and oxidation problems caused by prolonged air contact with the aluminum-lithium alloy, and ensuring uniform distribution of nanoparticles within the alloy. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: to provide a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material, comprising the following steps:

[0006] S1. Precast ingots for preparing nano-TiB2 / Al composite particles;

[0007] The aforementioned nano-TiB2 / Al composite particle precast ingot is produced by first mixing nano-TiB2 particles with micron-sized aluminum powder using a dry grinding high-energy ball milling method to create sub-millimeter-sized TiB2 / Al composite particles. Then, the composite particles are placed in a water-cooled concave copper mold for vacuum arc melting. After the composite particles are completely melted, electromagnetic stirring is applied, and the mixture is cooled with the mold to obtain the precast ingot. Using a dry grinding high-energy ball milling method to produce sub-millimeter-sized TiB2 / Al composite particles with high TiB2 content improves the spontaneous aggregation characteristics of the original nanoparticles, providing a good pre-dispersion effect for the subsequent distribution of TiB2 particles. It also avoids the oxidation and contamination problems caused by nano-TiB2 particles being exposed to air, and solves the problem of particles being blown away by the arc during subsequent high-vacuum arc melting.

[0008] S2. Place the aluminum-lithium based composite material raw materials in a low-vacuum stirred well melting furnace for melting to form a melt;

[0009] S3. After the aluminum-lithium-based composite material raw materials are completely melted, use a feeding system to add pure Li particles and aluminum-lithium alloy special commercial covering agent to the melted aluminum-lithium-based composite material raw materials, and introduce argon atmosphere for protection.

[0010] S4. Then, using another feeding system, a precast ingot of nano-TiB2 / Al composite particles is added to the molten aluminum-lithium-based composite material raw material. The molten aluminum-lithium-based composite material raw material is stirred to release the nano-TiB2 particles in the precast ingot into the molten aluminum-lithium-based composite material raw material. Stirring promotes the dispersion of nanoparticles and the homogeneity of the melt, resulting in an aluminum-lithium alloy melt containing nanoparticles.

[0011] S5. The aluminum-lithium alloy melt containing nanoparticles is poured into the mold through a leakage device and then subjected to ultrasonic vibration. The mold cavity is evacuated to maintain a preset vacuum level. After cooling, the mold is opened to obtain the nanoparticle-reinforced cast aluminum-lithium alloy.

[0012] The TiB2 / Al precast ingot obtained by this invention can be directly and quickly added to the aluminum-lithium alloy melt, solving the problem of difficulty in adding nanoparticles to molten aluminum. Under the dual protection of a low vacuum-argon atmosphere and flux, combined with short-term mechanical stirring, it can effectively promote the uniform dispersion of nanoparticles while avoiding the problem of severe hydrogen absorption in the aluminum-lithium alloy melt caused by the long mechanical stirring time in traditional external addition methods. Furthermore, it effectively improves the wettability between the reinforcing particles and the aluminum matrix, which is beneficial to improving the mechanical properties of the composite material.

[0013] This invention optimizes the order of raw material addition and temperature control during the smelting process, especially for the addition of pure Li particles and TiB2 / Al intermediate alloy ingots. It uses a dual secondary feeding system. One feeding system first adds pure Li particles and a commercially available covering agent for aluminum-lithium alloys. Then, another feeding system adds precast ingots of nano-TiB2 / Al composite particles to the molten aluminum-lithium-based composite material raw materials, thereby reducing the loss of pure Li and reducing the harm to material properties caused by phenomena such as hydrogen oxidative absorption.

[0014] The multidimensional indirect ultrasonic-assisted melt solidification technology provided by this invention, compared with traditional high-vacuum or non-vacuum direct solidification methods, can not only significantly reduce shrinkage cavities and porosity defects in the melt, but also effectively refine the microstructure and improve compositional segregation, thereby improving the quality and performance of castings. Furthermore, compared with high-vacuum casting, this method is more operable and lower in cost, while producing castings of higher quality than non-vacuum casting. Moreover, this method has no special restrictions on the composition of cast aluminum-lithium alloys and can even be extended to the casting of high-quality aluminum-lithium alloys, other aluminum-based composite materials, and other metallic materials. Simultaneously, the ultrasonic time in this method is as short as 30-120 seconds, and the number and position of the amplitude transformers can be selected according to the shape of the casting, greatly improving production efficiency.

[0015] This invention introduces nano-TiB2 particles into aluminum-lithium alloys via a liquid-state external precast ingot method. Unlike existing in-situ self-generated methods for preparing aluminum-lithium-based composite materials, this method avoids problems such as gas absorption, severe oxidation, and difficulty in controlling particle size and content caused by excessively high reaction temperatures. Furthermore, the aluminum-lithium-based composite material prepared by this invention possesses both excellent strength and plasticity, truly achieving an organic combination of the advantages of a lightweight, high-strength aluminum-lithium alloy matrix and high-performance ceramic particles.

[0016] The preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium composite material of the present invention is more operable. While completing the rapid addition of nanoparticles, it can effectively suppress the serious problems of hydrogen absorption and oxidation caused by prolonged contact with air in aluminum-lithium alloys, and ensure that the nanoparticles are uniformly distributed in the alloy.

[0017] Preferably, in step S1, the selected nano-TiB2 particles have a particle size of 20 to 100 nm, the nano-TiB2 particles account for 5 to 40% of the total mass of the composite particles, the ball mill speed is 200 to 300 rpm, and the particle size of the TiB2 / Al composite particles is 0.1 mm to 1 mm.

[0018] Preferably, in step S1, when vacuum arc melting is used, the arc current is 16 to 20A, and an electromagnetic stirrer is used for stirring at a speed of 100 to 200 rpm.

[0019] Preferably, the melting in step (2) is repeated multiple times to make the TiB2 particles uniformly dispersed in the melt.

[0020] Preferably, in step S2, the melting temperature is 700~750℃, and during the melting process, the melting furnace is evacuated and argon gas is used for washing, and the vacuum degree formed in the melting furnace is less than or equal to 5Pa.

[0021] In step S3, the Li particles are cylinders with a diameter greater than 3 mm. The surface of the Li particle raw material is covered with a layer of protective kerosene, and an appropriate amount of commercial aluminum-lithium alloy covering agent can be adhered. Before adding the Li particles, the melt temperature is reduced to 660~680℃ to avoid severe overburning and hydrogen absorption of Li due to excessive temperature. Subsequently, the temperature is raised to 700~720℃.

[0022] In step S4, the content of nano-TiB2 particles in the aluminum-lithium alloy melt after adding the precast ingot is 0~5wt.%, the stirring speed is 0~500rpm, the stirring time is 5~10min, the stirring temperature is 700~720℃, and the stirring head of the electromagnetic stirrer is placed 10mm above the bottom of the crucible to avoid significant fluctuations on the surface of the aluminum melt that could damage the protective coating, thereby promoting uniform dispersion of nanoparticles and effectively improving the problem of hydrogen absorption.

[0023] In step S5, the casting temperature of the aluminum-lithium alloy melt containing nanoparticles is 670~690℃, the ultrasonic power of the ultrasonic vibration is 0~8.4 kW, the ultrasonic time is 30~120s, the cavity of the mold includes but is not limited to round ingots, square ingots and other specific shapes, and the vacuum degree is less than or equal to 5Pa.

[0024] The beneficial effects of this invention are:

[0025] (1) The present invention uses high-energy ball milling to prepare TiB2 / Al composite particles with a mass fraction of sub-millimeter size or above, which not only improves the spontaneous aggregation characteristics of the original nanoparticles and avoids the oxidation and pollution problems caused by the nano TiB2 particles being exposed to air, but also solves the problem of the particles being blown away by the electric arc during subsequent high vacuum arc melting due to their small particle size.

[0026] (2) The present invention uses high vacuum electric arc melting to melt sub-millimeter TiB2 / Al composite particles prepared by high energy ball milling into precast ingots. Electromagnetic stirring is applied during the melting process to promote the uniform distribution of nano TiB2 particles in the precast ingots, which plays a good pre-dispersion role in the subsequent distribution of TiB2 particles in aluminum-lithium based composite materials.

[0027] (3) The TiB2 / Al precast ingot obtained by this invention can be directly and quickly added to the aluminum-lithium alloy melt, solving the problem of the difficulty in adding nanoparticles to aluminum liquid, especially the difficulty in adding particles to aluminum-lithium alloy melt. Under the dual protection of low vacuum-argon atmosphere and flux, combined with short-time mechanical stirring, it can effectively promote the uniform dispersion of nanoparticles while avoiding the problem of severe hydrogen absorption in aluminum-lithium alloy melt due to long mechanical stirring time in the traditional external addition method. It also effectively improves the wettability between reinforcing particles and aluminum matrix, which is beneficial to improving the mechanical properties of composite materials.

[0028] (4) The present invention optimizes the order of raw material addition and temperature control during the smelting process. In particular, for the addition of pure Li particles and TiB2 / Al intermediate alloy ingots, a secondary feeding system is used to reduce the loss of pure Li and reduce the harm to material properties caused by phenomena such as hydrogen absorption.

[0029] (5) The multidimensional indirect ultrasonic-assisted melt solidification technology provided by this invention, compared with traditional high vacuum or non-vacuum direct solidification methods, can not only significantly reduce shrinkage cavities and porosity defects in the melt, but also effectively refine the microstructure and improve compositional segregation, thereby improving the quality and performance of castings. In addition, compared with high vacuum casting, this new method is more operable and lower in cost, while producing castings of higher quality than non-vacuum casting. Furthermore, this new method has no special restrictions on the composition of cast aluminum-lithium alloys and can even be applied to the casting of high-quality aluminum-lithium alloys, other aluminum-based composite materials, and other metal materials. At the same time, the ultrasonic time in this new method is as short as 30~120s, and the number and position of the amplitude transformers can be selected according to the shape of the casting, greatly improving production efficiency.

[0030] (6) This invention introduces nano-TiB2 particles into aluminum-lithium alloys through liquid external feeding, which is different from the existing in-situ self-generated aluminum-lithium composite material preparation method. It can avoid problems such as gas absorption, severe oxidation and difficulty in controlling particle size and content caused by excessively high reaction temperature. In addition, the aluminum-lithium composite material prepared by this invention has both excellent strength and plasticity, and truly realizes the organic combination of the advantages of lightweight high-strength aluminum-lithium alloy matrix and high-performance ceramic particles.

[0031] (7) The present invention uses a dry grinding high-energy ball milling method to mix nano TiB2 particles with micron aluminum powder to produce sub-millimeter TiB2 / Al composite particles, and then produces a precast ingot of TiB2 / Al composite particles. Compared with the precast ingot of a structure such as a thin strip, more TiB2 particles can be added. In this way, more nano TiB2 particles can be released into the molten aluminum-lithium composite material raw material in the precast ingot, so that the TiB2 particle content in the aluminum-lithium composite material raw material is higher, thereby improving the performance of the composite material.

[0032] (8) In this invention, the aluminum-lithium alloy melt containing nanoparticles is poured into the mold through a liquid leakage device and then subjected to ultrasonic vibration. The mold cavity is evacuated to maintain a preset vacuum level. After cooling, the mold is opened to obtain the nanoparticle-reinforced cast aluminum-lithium alloy. Direct liquid leakage molding is used, without pressurizing the aluminum-lithium alloy melt. Large die-casting equipment is not required, the processing technology is simpler, the processing cost is lower, and the performance of the obtained composite material is still comparable to that of the composite material obtained by pressure molding. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0034] Figure 1 This is a process flow diagram of the preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material of the present invention;

[0035] Figure 2 This is a microscopic characterization diagram of the sample in the embodiment of the preparation method of the high-strength and tough nano-TiB2 reinforced aluminum lithium-based composite material of the present invention. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] A method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material includes the following steps:

[0038] Example 1: Reference Figure 1In this embodiment, the casting is a block-shaped ingot. The alloy composition of the ingot is as follows by mass percent: 2.5%Li, 1.5%Cu, 0.2%Sc, 0.5%TiB2, with the balance being Al. The nano-TiB2 / Al precast ingot contains 10wt.% nanoparticles.

[0039] This invention provides a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material. The specific manufacturing method is as follows:

[0040] S101: According to the ratio of TiB2 particles with a mass content of 10%, weigh TiB2 particles with an average particle size of 100nm and pure aluminum powder with an average particle size of 50μm, mix them evenly in a ball mill with a speed of 200rpm to make sub-millimeter TiB2 / Al composite particles, and use a high vacuum electric arc melting furnace to melt the composite particles into multiple precast ingots with a diameter of 10mm, with an arc current of 16A and an electromagnetic stirring speed of 100rpm;

[0041] S102: All alloy raw materials other than pure Li particles and TiB2 / Al precast ingots are placed in a low-vacuum stirred well melting furnace for melting. The melting temperature is 700~750℃. Vacuum is drawn in time during the melting process and argon gas is used for washing. The vacuum degree in the furnace is less than or equal to 5Pa.

[0042] S103: After the alloy raw materials are completely melted, pure Li particles with an appropriate amount of commercial covering agent for aluminum-lithium alloys adhering to their surface are added using one of the double secondary feeding systems. Before adding the Li particles, the melt temperature is reduced to 660~680℃ to avoid severe overheating and oxidation of Li due to excessive temperature. Then the temperature is raised to 700~720℃.

[0043] S104: Add TiB2 / Al precast ingots using another secondary feeding system, and then apply mechanical stirring (electromagnetic stirring) to the melt to accelerate the release of nano TiB2 particles in the precast ingots and promote the dispersion of nano particles and the homogeneity of the melt, to obtain an aluminum-lithium alloy composite melt containing nano particles. The stirring temperature is 700℃, the stirring speed is 300rpm, and the stirring time is 5min.

[0044] S105: The TiB2 / Al-2.5Li-1.5Cu composite melt was rapidly poured into the mold through a draining device. Ultrasonic vibration was activated to assist in melt solidification. Multiple sets of indirect ultrasonic amplitude transformers in the ultrasonic vibration device acted on the outer wall of the mold, forming multi-dimensional ultrasonic components for better ultrasonic effects. The melt pouring temperature was 670~690℃, the indirect ultrasonic power was 2.8kW, and the ultrasonic time was 60s. The vacuum degree of the mold cavity was less than or equal to 5Pa throughout the pouring process. After cooling, the mold was opened to obtain a square casting of nanoparticle-reinforced aluminum-lithium-based composite material. The microstructure of the casting sample is as follows: Figure 2 As shown;

[0045] Example 2: The casting in this example is a circular ingot. The alloy composition of the ingot is as follows by mass percentage: 0.6% Li, 4.5% Cu, 5% TiB2, with the balance being Al. The nano-TiB2 / Al precast ingot contains 40 wt.% nanoparticles.

[0046] like Figure 1 As shown, the present invention provides a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material. The specific manufacturing method is as follows:

[0047] S101: According to the ratio of TiB2 particles with a mass content of 20%, weigh TiB2 particles with an average particle size of 100nm and pure aluminum powder with an average particle size of 50μm, mix them evenly in a ball mill with a speed of 300rpm to make sub-millimeter TiB2 / Al composite particles, and use a high vacuum electric arc melting furnace to melt the composite particles into multiple precast ingots with a diameter of 10mm, with an arc current of 20A and an electromagnetic stirring speed of 200rpm;

[0048] S102: Place all raw materials except pure Li particles and TiB2 / Al precast ingots into a low-vacuum stirred well melting furnace for melting. The melting temperature is 700~750℃. Vacuum is drawn in time during the melting process and argon gas is used for gas washing. The vacuum degree in the furnace is less than or equal to 5Pa.

[0049] S103: After the alloy raw materials are completely melted, pure Li particles with an appropriate amount of commercial covering agent for aluminum-lithium alloys adhering to their surface are added using one of the double secondary feeding systems. Before adding the Li particles, the melt temperature is reduced to 660~680℃ to avoid severe overheating and oxidation of Li due to excessive temperature. Then the temperature is raised to 700~720℃.

[0050] S104: Using another secondary feeding system, TiB2 / Al precast ingots are added, and then mechanical stirring (electromagnetic stirring) is applied to the melt to accelerate the release of nano TiB2 particles from the precast ingots into the melt and promote the dispersion of nanoparticles and the homogeneity of the melt, so as to obtain an aluminum-lithium alloy composite melt containing nanoparticles. The stirring temperature is 700℃, the stirring speed is 500rpm, and the stirring time is 10min.

[0051] S105: The TiB2 / Al-0.3Li-4.5Cu composite melt is rapidly poured into the mold through a liquid-pouring device. Ultrasonic vibration is activated to assist in the solidification of the melt. Multiple sets of indirect ultrasonic amplitude rods in the ultrasonic vibration device act on the outer wall of the mold to form multi-dimensional ultrasonic components, resulting in better ultrasonic effects. The melt pouring temperature is 670~690℃, the indirect ultrasonic power is 8.4kW, and the ultrasonic time is 120s. The vacuum degree of the mold cavity is less than or equal to 5Pa throughout the process. After cooling, the mold is opened to obtain a circular casting of nanoparticle-reinforced aluminum-lithium-based composite material.

[0052] Example 3: The casting in this example is a Z-shaped ingot. The alloy composition of the ingot is as follows by mass percent: 2% Li, 2% Cu, 0.5% Mg, 0.2% Zr, 0.15% Ag, 1% TiB2, with the balance being Al. The nano-TiB2 / Al precast ingot contains 20 wt.% nanoparticles.

[0053] This invention provides a method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material. The specific manufacturing method is as follows:

[0054] S101: According to the ratio of TiB2 particle content of 20%, weigh TiB2 particles with an average particle size of 100nm and pure aluminum powder with an average particle size of 50μm, mix them evenly in a ball mill with a speed of 250rpm to make sub-millimeter TiB2 / Al composite particles, and use a high vacuum electric arc melting furnace to melt the composite particles into multiple precast ingots with a diameter of 10mm, the arc current is 18A, and the electromagnetic stirring speed is 150rpm;

[0055] S102: Place all raw materials except pure Li particles and TiB2 / Al precast ingots into a low-vacuum stirred well melting furnace for melting. The melting temperature is 700~750℃. Vacuum is drawn in time during the melting process and argon gas is used for gas washing. The vacuum degree in the furnace is less than or equal to 5Pa.

[0056] S103: After the alloy raw materials are completely melted, pure Li particles with an appropriate amount of commercial covering agent for aluminum-lithium alloys adhering to their surface are added using one of the double secondary feeding systems. Before adding the Li particles, the melt temperature is reduced to 660~680℃ to avoid severe overheating and oxidation of Li due to excessive temperature. Then the temperature is raised to 700~720℃.

[0057] S104: Add TiB2 / Al precast ingots using another secondary feeding system, and then apply mechanical stirring (electromagnetic stirring) to the melt to accelerate the release of nano TiB2 particles in the precast ingots and promote the dispersion of nano particles and the homogeneity of the melt, so as to obtain an aluminum-lithium alloy melt containing nano particles. The stirring temperature is 700℃, the stirring speed is 400rpm, and the stirring time is 8min.

[0058] S105: The TiB2 / Al-2Li-2Cu composite melt is rapidly poured into the mold through a leakage device. Ultrasonic vibration is activated to assist in the solidification of the melt. Multiple sets of indirect ultrasonic amplitude rods in the ultrasonic vibration device act on the outer wall of the mold to form multi-dimensional ultrasonic components, resulting in better ultrasonic effects. The melt pouring temperature is 670~690℃, the indirect ultrasonic power is 5.6kW, and the ultrasonic time is 90s. The vacuum degree of the mold cavity is less than or equal to 5Pa throughout the pouring process. After cooling, the mold is opened to obtain a Z-shaped casting of nanoparticle-reinforced aluminum-lithium-based composite material.

[0059] Table 1 shows the composition of the cast aluminum-lithium alloy materials prepared in different embodiments and the test results of their as-cast tensile mechanical properties (tensile strength, yield strength, and elongation). The results show that the nanoparticle-containing cast aluminum-lithium alloy provided by the present invention has high strength and good toughness, and its as-cast comprehensive mechanical properties are higher than those of existing particle-reinforced cast aluminum-lithium alloy composite materials, especially in terms of elongation.

[0060] Table 1:

[0061]

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a high-strength and tough nano-TiB2 reinforced aluminum-lithium-based composite material, comprising die-casting an aluminum alloy material poured into a mold using a die-casting machine, characterized in that: The steps include: S1. Precast ingots for preparing nano-TiB2 / Al composite particles; The aforementioned nano-TiB2 / Al composite particle precast ingot is prepared by first mixing nano-TiB2 particles with micron-sized aluminum powder using a dry grinding high-energy ball milling method to produce sub-millimeter-sized TiB2 / Al composite particles. Then, the composite particles are placed in a water-cooled concave copper mold for vacuum arc melting. After the composite particles are completely melted, electromagnetic stirring is applied, and the mixture is cooled with the mold to obtain the precast ingot. The selected nano-TiB2 particles have a particle size of 20-100 nm, and the nano-TiB2 particles account for 5-40% of the total mass of the composite particles. The ball mill speed is 200-300 rpm, and the particle size of the TiB2 / Al composite particles is 0.1 mm-1 mm. S2. Place the aluminum-lithium based composite material raw materials in a low-vacuum stirred well melting furnace for melting to form a melt; S3. After the aluminum-lithium-based composite material raw materials are completely melted, add pure Li particles and commercial covering agent for aluminum-lithium alloy to the melted aluminum-lithium-based composite material raw materials. S4. Then, a precast ingot of nano-TiB2 / Al composite particles is added to the molten aluminum-lithium-based composite material raw material. The molten aluminum-lithium-based composite material raw material is stirred to release the nano-TiB2 particles in the precast ingot into the molten aluminum-lithium-based composite material raw material, thereby obtaining an aluminum-lithium alloy melt containing nanoparticles. S5. The aluminum-lithium alloy melt containing nanoparticles is poured into the mold through a liquid leakage device and then subjected to ultrasonic vibration. The mold cavity is evacuated to maintain a preset vacuum level. After cooling, the mold is opened to obtain the nanoparticle-reinforced cast aluminum-lithium alloy. In step S4, the content of nano-TiB2 particles in the aluminum-lithium alloy melt after adding the precast ingot is 0.5~5wt.%, the stirring speed is 300~500rpm, the stirring time is 5~10min, the stirring temperature is 700~720℃, and the stirring head of the electromagnetic stirrer is placed 10mm above the bottom of the crucible. In step S5, the casting temperature of the aluminum-lithium alloy melt containing nanoparticles is 670~690℃, the ultrasonic power of the ultrasonic vibration is 2.8~8.4 kW, the ultrasonic time is 30~120s, and the vacuum degree is less than or equal to 5Pa.

2. The preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium based composite material as described in claim 1, characterized in that, In step S1, when vacuum arc melting is used, the arc current is 16 ~ 20A, and an electromagnetic stirrer is used for stirring at a speed of 100 ~ 200 rpm.

3. The preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium based composite material as described in claim 2, characterized in that, The melting in step S2 is a repeated melting process to ensure that the TiB2 particles are uniformly dispersed in the melt.

4. The preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium based composite material as described in claim 3, characterized in that, In step S2, the melting temperature is 700~750℃. During the melting process, the melting furnace is evacuated and argon gas is used for cleaning. The vacuum degree formed in the melting furnace is less than or equal to 5Pa.

5. The preparation method of the high-strength and tough nano-TiB2 reinforced aluminum-lithium based composite material as described in claim 4, characterized in that, In step S3, the Li particles are cylinders with a diameter greater than 3 mm. The surface of the Li particle raw material is covered with a layer of protective kerosene. Before adding the Li particles, the melt temperature is reduced to 660~680℃, and then the temperature is raised to 700~720℃.

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