High-toughness bending-resistant aluminum alloy material and preparation method thereof

Abstract

The invention discloses a high-toughness bending-resistant aluminum alloy material and a preparation method thereof, and belongs to the technical field of aluminum alloy materials, and the high-toughness bending-resistant aluminum alloy material comprises the following components in percentage by mass: 1.5%-3.0% of Zn, 1.0%-2.0% of Mg, 0.3%-0.5% of Mn, 0.2%-0.4% of Ti, 0.4%-0.6% of Li, 0.1%-0.3% of aluminum oxide nanoparticles, 0.18%-0.6% of boron nitride nanofibers and the balance of aluminum. Impurity elements are less than or equal to 0.1%, and the balance is Al. Through the synergistic effect of the boron nitride nanofibers and the aluminum oxide nanoparticles, the strength and toughness of the material are improved. In the preparation process, the lithium powder and the boron nitride nanofibers are mixed and then fused, the aluminum oxide nanoparticles are put into the lithium melt, lithium oxidation is inhibited, dispersion of the boron nitride nanofibers and the aluminum oxide nanoparticles is promoted, densification of the aluminum alloy is promoted, and the toughness is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy materials, and particularly relates to a high-toughness and bend-resistant aluminum alloy material and a preparation method thereof. Background Art

[0002] As an important lightweight material, aluminum alloy is widely used in modern industry. Its excellent properties, such as high specific strength, good corrosion resistance and plasticity, make it an advanced material in the fields of aerospace, automobile manufacturing, construction, etc.

[0003] The main component of aluminum alloy is aluminum (Al). By adding other elements such as copper (Cu), magnesium (Mg), silicon (Si), zinc (Zn), etc., various alloys with different properties are formed. Pure aluminum has poor toughness. Even though other elements are added to the aluminum alloy to improve its toughness, the toughness of the aluminum alloy is still not as good as that of some other metals, such as steel. At present, adding fibers or other rare earth elements is usually adopted to improve the toughness of aluminum alloy.

[0004] The Chinese invention patent with the publication number CN115747591A discloses a high-toughness aluminum alloy material and its preparation process. By using carbon fiber-coated alumina as the reinforcing phase, the strength and toughness of the aluminum alloy are effectively improved. However, in the whole preparation process, it is necessary to prepare the carbon fiber-coated alumina precursor first. The raw material preparation work is complex, the energy consumption is high, and the cost increases, which does not meet the economic benefit requirements of actual production.

[0005] The Chinese invention patent with the publication number CN107130152A discloses a high-toughness aluminum alloy material and its preparation method. By adding cerium and scandium to the aluminum alloy material, the strength of the aluminum alloy material is improved; by adding zirconium and gadolinium to the aluminum alloy material, the toughness of the aluminum alloy material is improved. Although zirconium and gadolinium can improve the toughness of the aluminum alloy material, gadolinium, as a rare earth element, has limited sources and high prices. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-toughness and bend-resistant aluminum alloy material and a preparation method thereof, which can effectively improve the toughness and bend resistance of the aluminum alloy material, and the preparation method is simple, the cost is low, and it can be applied to actual production.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage:

[0009] Zn: 1.5% - 3.0%, Mg: 1.0% - 2.0%, Mn: 0.3% - 0.5%, Ti: 0.2% - 0.4%, Li: 0.4% - 0.6%, alumina nanoparticles: 0.1% - 0.3%, boron nitride nanofibers 0.18% - 0.6%, impurity elements ≤ 0.1%, the balance is Al.

[0010] The addition of lithium causes a change in the microstructure of the aluminum alloy. By promoting the formation of precipitation phases (such as Al 3 Li), it hinders the movement of dislocations, thereby improving the strength and toughness of the alloy.

[0011] Furthermore, the diameter of the boron nitride nanofibers is 20 - 100 nm. Boron nitride nanofibers are a kind of pure white polycrystalline fiber with a crystal structure similar to that of graphite. Boron nitride fibers are stable in molten metals and can still exist stably in air at about 900 °C. Boron nitride fibers exist in the alloy material in a stable fiber structure. The mutual entanglement of the fibers can inhibit crack propagation, improve the toughness of the alloy material, and boron nitride nanofibers have high strength, low density, and excellent thermal stability, which can significantly enhance the mechanical properties of the aluminum alloy.

[0012] Furthermore, the particle size of the alumina nanoparticles is 30 - 60 nm. Alumina nanoparticles have a high melting point and oxidation resistance. Adding alumina nanoparticles to the aluminum alloy, due to the hard particles hindering grain growth, the grain size is refined, promoting the densification of the aluminum alloy, reducing the porosity, and improving the toughness. Directly adding alumina nanoparticles to the aluminum alloy melt is prone to agglomeration,

[0013] Furthermore, the mass ratio of the alumina nanoparticles to the boron nitride nanofibers is 1:1.5 - 2.5. Boron nitride nanofibers can act as a "bridge" to evenly distribute the alumina nanoparticles in the matrix, thereby improving the strength and toughness of the material, effectively preventing crack propagation, and enhancing the overall performance of the aluminum alloy.

[0014] Furthermore, the mass ratio of the total mass of the alumina nanoparticles and the boron nitride nanofibers to the mass of Li is 0.7 - 1.5:1.

[0015] The present invention also provides a preparation method of the high-toughness and bend-resistant aluminum alloy material as described above, including the following steps:

[0016] Step 1: Stir and mix lithium powder and boron nitride nanofibers, and under an inert atmosphere, put them into a melting furnace and heat up to melt. After the lithium powder is completely melted, put in the alumina nanoparticles and stir and mix evenly;

[0017] Since lithium is an active metallic element, it is prone to oxidation reactions at high temperatures, resulting in poor thermal stability of the alloy. By melting and mixing lithium with boron nitride, the oxidation of lithium can be inhibited. Moreover, boron nitride has a low surface energy and shows non-wettability when melted with the liquid metal aluminum alloy, making it difficult to form good contact with the metal. First, boron nitride nanofibers are mixed with molten lithium, and chemical interactions between the molten lithium and boron nitride in-situ form Li-N bonds, which can improve the interfacial compatibility.

[0018] In the presence of lithium, during the smelting process, the high activity of lithium will erode the surface protective film of alumina nanoparticles, generating lithium-aluminum compounds (such as LiAlO 2 ), making its surface structure rougher. When stirred and mixed in the melt, the irregularity of the rough surface will cause a greater energy barrier at the contact points of the particles, inhibiting aggregation and promoting the dispersion of alumina nanoparticles in the melt.

[0019] Step 2: Heat the smelting furnace to 750 - 780 °C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the smelting process until the metal is completely melted;

[0020] Step 3: After holding for 20 - 30 minutes after melting, heat up to 950 - 1000 °C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metal is completely melted;

[0021] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. After solution treatment, perform step-by-step artificial aging treatment, and naturally cool to room temperature to obtain a high-toughness and bend-resistant aluminum alloy material.

[0022] Further, the inert atmosphere is one of argon, helium, neon, xenon, and nitrogen.

[0023] Further, the purity of the lithium powder, zinc ingots, magnesium ingots, aluminum ingots, manganese ingots, and titanium ingots ≥ 99.9%.

[0024] Further, the steps of the solution treatment are: heat the aluminum alloy ingot to 450 - 500 °C and hold for 6 - 10 hours, and cool to room temperature by water quenching or air cooling. Water quenching or air cooling can rapidly cool, which helps the uniform distribution of the precipitated phase.

[0025] Further, the initial aging temperature of the step-by-step artificial aging treatment is 120 - 130 °C, the duration is 3 - 5 hours, the subsequent aging temperature is 150 - 160 °C, and the duration is 4 - 6 hours. Step-by-step artificial aging treatment can shorten the aging time and improve the microstructure and comprehensive properties of the aluminum alloy.

[0026] The beneficial effects of the present invention:

[0027] (1) Alumina nanoparticles and boron nitride nanofibers are added to the aluminum alloy raw materials of the present invention. Through the synergistic effect of the nanofibers and nanoparticles, the strength and toughness of the material are improved, the crack propagation is effectively prevented, and the overall performance of the aluminum alloy is enhanced.

[0028] (2) Lithium element is added to the aluminum alloy raw materials of the present invention to promote the formation of precipitation phases (such as Al 3 Li), hinder the movement of dislocations, improve the strength and toughness of the alloy, enhance the bending resistance performance, and the price cost of lithium element is lower than that of rare earth elements, which can reduce the alloy preparation cost.

[0029] (3) In the process of preparing the aluminum alloy of the present invention, lithium powder and boron nitride nanofibers are first mixed and then melted. The chemical interaction between molten lithium and boron nitride in-situ forms Li-N bonds, which inhibits the oxidation of lithium while improving the interfacial compatibility of boron nitride nanofibers in the aluminum alloy, promotes the dispersion of boron nitride nanofibers, and improves the toughening effect.

[0030] (4) In the process of preparing the aluminum alloy of the present invention, alumina nanoparticles are put into the lithium melt. The high activity of lithium will erode the surface protective film of the alumina nanoparticles, generating lithium-aluminum compounds, roughening the surface structure of the alumina nanoparticles, promoting the dispersion of the alumina nanoparticles in the melt, promoting the densification of the aluminum alloy, reducing the porosity, and improving the toughness. Detailed implementation mode

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] The purity of lithium powder, zinc ingot, magnesium ingot, aluminum ingot, manganese ingot and titanium ingot used in the embodiments is ≥99.9%.

[0033] Embodiment 1

[0034] This embodiment provides a high-toughness and bending-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.5%, alumina nanoparticles (diameter 50-100nm): 0.1%, boron nitride nanofibers (particle size 40-60nm): 0.25%, impurity elements ≤0.1%, and the balance is Al.

[0035] The preparation method of the high-toughness and bending-resistant aluminum alloy material includes the following steps:

[0036] Step 1: Stir and mix lithium powder and boron nitride nanofibers. Under an argon atmosphere, put them into a melting furnace and heat up to 190°C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir to mix evenly.

[0037] Step 2: Heat the melting furnace to 760°C, add zinc ingots, magnesium ingots, and aluminum ingots. Use argon protection during the melting process until the metals are completely melted.

[0038] Step 3: Keep the temperature for 30 minutes after melting and then heat up to 950°C. Add manganese ingots and titanium ingots. After the metals are completely melted, an aluminum alloy solution is obtained.

[0039] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480°C and keep it for 8 hours, then cool it to room temperature by water quenching. Heat the aluminum alloy ingot to 120°C and keep it for 4 hours, and then heat it to 150°C and keep it for 5 hours to complete the step-by-step artificial aging treatment. Naturally cool it to room temperature to obtain a high-toughness and bend-resistant aluminum alloy material.

[0040] Example 2

[0041] The difference from Example 1 is only that the mass percentage of boron nitride nanofibers in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.25% to 0.2%, and the mass percentage of Li is adjusted from 0.5% to 0.43% (while keeping the total mass ratio of alumina nanoparticles and boron nitride nanofibers to Li as 0.7:1).

[0042] This example provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.43%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.1%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.2%, impurity elements ≤ 0.1%, and the balance is Al.

[0043] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0044] Step 1: Stir and mix lithium powder and boron nitride nanofibers. Under an argon atmosphere, put them into a melting furnace and heat up to 190°C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir to mix evenly.

[0045] Step 2: Heat the melting furnace to 760°C, add zinc ingots, magnesium ingots, and aluminum ingots. Use argon protection during the melting process until the metals are completely melted.

[0046] Step 3: Keep the temperature for 30 minutes after melting and then heat up to 950°C. Add manganese ingots and titanium ingots. After the metals are completely melted, an aluminum alloy solution is obtained.

[0047] Step 4: Cool the aluminum alloy solution and then vacuum cast it to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then water quench it to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, and then heat it to 150 °C and hold for 5 h to complete the step-by-step artificial aging treatment. Naturally cool it to room temperature to obtain the high-toughness and bend-resistant aluminum alloy material.

[0048] Example 3

[0049] The difference from Example 1 is only that the mass percentage of boron nitride nanofibers in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.25% to 0.15%, and the mass percentage of Li is adjusted from 0.5% to 0.36% (while maintaining the total mass ratio of alumina nanoparticles and boron nitride nanofibers to Li at 0.7:1).

[0050] This example provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.36%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.1%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.15%, impurity elements ≤ 0.1%, and the balance is Al.

[0051] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0052] Step 1: Stir and mix lithium powder and boron nitride nanofibers, and under an argon atmosphere, put them into a melting furnace and heat to 190 °C for melting. After the lithium powder is completely melted, put in the alumina nanoparticles and stir and mix evenly.

[0053] Step 2: Heat the melting furnace to 760 °C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted.

[0054] Step 3: After melting, hold for 30 min and then heat to 950 °C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0055] Step 4: Cool the aluminum alloy solution and then vacuum cast it to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then water quench it to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, and then heat it to 150 °C and hold for 5 h to complete the step-by-step artificial aging treatment. Naturally cool it to room temperature to obtain the high-toughness and bend-resistant aluminum alloy material.

[0056] Example 4

[0057] The difference from Example 1 is only that the mass percentage of alumina nanoparticles in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.1% to 0.157%, the mass percentage of boron nitride nanofibers is adjusted from 0.25% to 0.3925%, and the mass ratio of the total mass of alumina nanoparticles and boron nitride nanofibers to the mass of Li is 1.1:1.

[0058] This example provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.5%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.157%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.3925%, impurity elements ≤ 0.1%, and the balance is Al.

[0059] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0060] Step 1: Stir and mix lithium powder and boron nitride nanofibers, and under an argon atmosphere, put them into a melting furnace and heat up to 190 °C for melting. After the lithium powder is completely melted, put in the alumina nanoparticles and stir and mix evenly.

[0061] Step 2: Heat the melting furnace to 760 °C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted.

[0062] Step 3: Keep the temperature for 30 min after melting and then heat up to 950 °C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0063] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and keep it warm for 8 h, cool it to room temperature by water quenching, heat the aluminum alloy ingot to 120 °C and keep it warm for 4 h, and then heat it to 150 °C and keep it warm for 5 h to complete the step-by-step artificial aging treatment, and then naturally cool it to room temperature to obtain the high-toughness and bend-resistant aluminum alloy material.

[0064] Example 5

[0065] The difference from Example 1 is only that the mass percentage of alumina nanoparticles in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.1% to 0.214%, the mass percentage of boron nitride nanofibers is adjusted from 0.25% to 0.535%, and the mass ratio of the total mass of alumina nanoparticles and boron nitride nanofibers to the mass of Li is 1.5:1.

[0066] This embodiment provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.5%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.214%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.535%, impurity elements ≤ 0.1%, and the balance is Al.

[0067] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0068] Step 1: Stir and mix lithium powder and boron nitride nanofibers, and put them into a melting furnace under an argon atmosphere and heat up to 190°C for melting. After the lithium powder is completely melted, put in alumina nanoparticles and stir and mix evenly.

[0069] Step 2: Heat the melting furnace to 760°C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted.

[0070] Step 3: Keep the temperature for 30 minutes after melting and then heat up to 950°C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0071] Step 4: Cool the aluminum alloy solution and then vacuum cast it to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480°C and keep it warm for 8 hours, then cool it to room temperature by water quenching. Heat the aluminum alloy ingot to 120°C and keep it warm for 4 hours, and then heat it to 150°C and keep it warm for 5 hours to complete the step-by-step artificial aging treatment, and then naturally cool it to room temperature to obtain the high-toughness and bend-resistant aluminum alloy material.

[0072] Example 6

[0073] The difference from Example 4 is only that the mass percentage of Li in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.5% to 0.4%, the mass percentage of alumina nanoparticles is adjusted from 0.157% to 0.126%, the mass percentage of boron nitride nanofibers is adjusted from 0.3925% to 0.315%, and the mass ratio of the total mass of alumina nanoparticles and boron nitride nanofibers to the mass of Li is 1.1:1.

[0074] This embodiment provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.4%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.126%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.315%, impurity elements ≤ 0.1%, and the balance is Al.

[0075] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0076] Step 1: Stir and mix lithium powder and boron nitride nanofibers. Under an argon atmosphere, put them into a melting furnace and heat up to 190 °C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir and mix evenly.

[0077] Step 2: Heat the melting furnace to 760 °C, add zinc ingots, magnesium ingots, and aluminum ingots. The melting process is protected by argon until the metals are completely melted.

[0078] Step 3: Keep the temperature for 30 min after melting and then heat up to 950 °C. Add manganese ingots and titanium ingots. After the metals are completely melted, an aluminum alloy solution is obtained.

[0079] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and keep it for 8 h, then water quench to room temperature. Heat the aluminum alloy ingot to 120 °C and keep it for 4 h, and then heat up to 150 °C and keep it for 5 h to complete the step-by-step artificial aging treatment. Naturally cool to room temperature to obtain a high-toughness and bend-resistant aluminum alloy material.

[0080] Example 7

[0081] The difference from Example 4 is only that the mass percentage of Li in the high-toughness and bend-resistant aluminum alloy material is adjusted from 0.5% to 0.6%, the mass percentage of alumina nanoparticles is adjusted from 0.157% to 0.189%, the mass percentage of boron nitride nanofibers is adjusted from 0.3925% to 0.4725%, and the mass ratio of the total mass of alumina nanoparticles and boron nitride nanofibers to the mass of Li is 1.1:1.

[0082] This example provides a high-toughness and bend-resistant aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.6%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.189%, boron nitride nanofibers (with a particle size of 40 - 60 nm): 0.4725%, impurity elements ≤ 0.1%, and the balance is Al.

[0083] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0084] Step 1: Stir and mix lithium powder and boron nitride nanofibers. Under an argon atmosphere, put them into a melting furnace and heat up to 190 °C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir and mix evenly.

[0085] Step 2: Heat the melting furnace to 760 °C, add zinc ingots, magnesium ingots, and aluminum ingots. The melting process is protected by argon until the metals are completely melted.

[0086] Step 3: After melting and holding for 30 min, heat up to 950 °C, add manganese ingots and titanium ingots. After the metals are completely melted, an aluminum alloy solution is obtained.

[0087] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then water quench to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, then heat up to 150 °C and hold for 5 h to complete the step-by-step artificial aging treatment, and then naturally cool to room temperature to obtain a high-toughness and bend-resistant aluminum alloy material.

[0088] Example 8

[0089] The difference from Example 1 is only that the mass percentages of the components in the high-toughness and bend-resistant aluminum alloy material are different, specifically as follows:

[0090] Zn: 1.5%, Mg: 1.0%, Mn: 0.3%, Ti: 0.2%, Li: 0.5%, alumina nanoparticles (diameter 50 - 100 nm): 0.1%, boron nitride nanofibers (particle size 40 - 60 nm): 0.25%, impurity elements ≤ 0.1%, and the balance is Al.

[0091] The preparation method of the high-toughness and bend-resistant aluminum alloy material includes the following steps:

[0092] Step 1: Stir and mix lithium powder and boron nitride nanofibers. Under an argon atmosphere, put them into a melting furnace and heat up to 190 °C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir and mix evenly.

[0093] Step 2: Heat the melting furnace to 750 °C, add zinc ingots, magnesium ingots, and aluminum ingots. During the melting process, use argon protection until the metals are completely melted.

[0094] Step 3: After melting and holding for 30 min, heat up to 950 °C, add manganese ingots and titanium ingots. After the metals are completely melted, an aluminum alloy solution is obtained.

[0095] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 460 °C and hold for 10 h, then water quench to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 5 h, then heat up to 150 °C and hold for 6 h to complete the step-by-step artificial aging treatment, and then naturally cool to room temperature to obtain a high-toughness and bend-resistant aluminum alloy material.

[0096] Example 9

[0097] The difference from Example 1 is only that the mass percentages of the components in the high-toughness and bend-resistant aluminum alloy material are different, specifically as follows:

[0098] Zn: 3.0%, Mg: 2.0%, Mn: 0.5%, Ti: 0.4%, Li: 0.5%, alumina nanoparticles (diameter 50 - 100 nm): 0.1%, boron nitride nanofibers (particle size 40 - 60 nm): 0.25%, impurity elements ≤ 0.1%, balance Al.

[0099] The preparation method of the high - toughness and bend - resistant aluminum alloy material comprises the following steps:

[0100] Step 1: Stir and mix lithium powder and boron nitride nanofibers, put them into a melting furnace under an argon atmosphere, heat up to 190 °C for melting. After the lithium powder is completely melted, put in alumina nanoparticles and stir and mix evenly;

[0101] Step 2: Heat up the melting furnace to 780 °C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted;

[0102] Step 3: Keep the temperature for 30 min after melting and then heat up to 980 °C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0103] Step 4: Cool the aluminum alloy solution and then vacuum - cast to obtain an aluminum alloy ingot. Heat up the aluminum alloy ingot to 480 °C and keep it for 10 h, then use water quenching to cool it to room temperature. Heat up the aluminum alloy ingot to 130 °C and keep it for 4 h, and then heat up to 160 °C and keep it for 6 h to complete the step - by - step artificial aging treatment, and then naturally cool it to room temperature to obtain the high - toughness and bend - resistant aluminum alloy material.

[0104] Comparative Example 1

[0105] Compared with Example 1, in this comparative example, alumina nanoparticles are not added to the components of the aluminum alloy material.

[0106] This comparative example provides an aluminum alloy material, which comprises the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.5%, boron nitride nanofibers (particle size 40 - 60 nm): 0.25%, impurity elements ≤ 0.1%, balance Al.

[0107] The preparation method of the aluminum alloy material comprises the following steps:

[0108] Step 1: Stir and mix lithium powder and boron nitride nanofibers, put them into a melting furnace under an argon atmosphere, heat up to 190 °C for melting until the lithium powder is completely melted;

[0109] Step 2: Heat up the melting furnace to 760 °C, put in zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted;

[0110] Step 3: After melting and holding for 30 min, heat up to 950 °C, add manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0111] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then water quench to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, then heat up to 150 °C and hold for 5 h to complete the stepped artificial aging treatment, and naturally cool to room temperature to obtain the aluminum alloy material.

[0112] Comparative Example 2

[0113] Compared with Example 1, boron nitride nanofibers are not added to the components of the aluminum alloy material in this comparative example.

[0114] This comparative example provides an aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, Li: 0.5%, alumina nanoparticles (with a diameter of 50 - 100 nm): 0.1%, impurity elements ≤ 0.1%, and the balance is Al.

[0115] The preparation method of the aluminum alloy material includes the following steps:

[0116] Step 1: Under an argon atmosphere, put lithium powder into a melting furnace and heat up to 190 °C for melting. After the lithium powder is completely melted, add alumina nanoparticles and stir to mix evenly.

[0117] Step 2: Heat the melting furnace to 760 °C, add zinc ingots, magnesium ingots, and aluminum ingots, and use argon protection during the melting process until the metals are completely melted.

[0118] Step 3: After melting and holding for 30 min, heat up to 950 °C, add manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0119] Step 4: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then water quench to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, then heat up to 150 °C and hold for 5 h to complete the stepped artificial aging treatment, and naturally cool to room temperature to obtain the aluminum alloy material.

[0120] Comparative Example 3

[0121] Compared with Example 1, Li is not added to the components of the aluminum alloy material in this comparative example.

[0122] This comparative example provides an aluminum alloy material, which includes the following components by mass percentage: Zn: 2.0%, Mg: 1.5%, Mn: 0.4%, Ti: 0.3%, alumina nanoparticles (diameter: 50 - 100 nm): 0.1%, boron nitride nanofibers (particle size: 40 - 60 nm): 0.25%, impurity elements ≤ 0.1%, and the balance is Al.

[0123] The preparation method of the aluminum alloy material includes the following steps:

[0124] Step 1: Put zinc ingots, magnesium ingots, and aluminum ingots into a melting furnace, heat up to 760 °C, and use argon protection during the melting process until the metals are completely melted, then put in boron nitride nanofibers and alumina nanoparticles and stir to mix.

[0125] Step 2: After holding for 30 min, heat up to 950 °C, put in manganese ingots and titanium ingots, and obtain an aluminum alloy solution after the metals are completely melted.

[0126] Step 3: Cool the aluminum alloy solution and then vacuum cast to obtain an aluminum alloy ingot. Heat the aluminum alloy ingot to 480 °C and hold for 8 h, then use water quenching to cool to room temperature. Heat the aluminum alloy ingot to 120 °C and hold for 4 h, and then heat up to 150 °C and hold for 5 h to complete the stepped artificial aging treatment, and then naturally cool to room temperature to obtain the aluminum alloy material.

[0127] Perform performance tests on the aluminum alloy materials prepared in Examples 1 - 9 and Comparative Examples 1 - 3, and the results are shown in Table 1:

[0128] Table 1

[0129] Project Tensile strength MPa Yield strength MPa Elongation % Flexural strength MPa Example 1 548.6 404.3 12.4 312.2 Example 2 536.7 393.9 11.8 301.3 Example 3 532.5 388.1 11.6 295.7 Example 4 554.5 416.7 12.9 318.4 Example 5 543.0 401.2 12.2 309.5 Example 6 550.3 412.5 12.4 313.1 Example 7 546.2 410.2 12.3 311.6 Example 8 540.9 392.5 11.8 302.4 Example 9 546.6 397.0 11.9 305.0 Comparative Example 1 395.2 203.1 7.2 154.8 Comparative Example 2 347.3 188.7 5.5 132.1 Comparative Example 3 353.6 198.6 6.1 140.0

[0130] It can be seen from Table 1 that in Examples 1 - 3, as the mass ratio of alumina nanoparticles to boron nitride nanofibers increases, due to the weakened synergistic effect between nanofibers and nanoparticles, the toughness of the prepared aluminum alloy material decreases; in Example 4, the mass ratio of the total mass of alumina nanoparticles and boron nitride nanofibers to the mass of Li is 1.1:1, which is the optimal ratio, and the prepared aluminum alloy has the best comprehensive performance and excellent bending resistance; in Examples 6 and 7, too high or too low proportion of lithium element will reduce the mechanical properties of the aluminum alloy material. For the aluminum alloy materials prepared without alumina nanoparticles or boron nitride nanofibers, due to the lack of synergistic effect and the toughening effect of the two materials themselves, the aluminum alloy materials prepared in Comparative Examples 1 and 2 have poor toughness. In the material of Comparative Example 3, Li is not added, and the performance indexes of the prepared aluminum alloy material are much lower than those of Example 1.

[0131] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0132] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-toughness and bending-resistant aluminum alloy material, characterized in that: Calculated by mass percentage, it includes the following components: Zn: 1.5%-3.0%, Mg: 1.0%-2.0%, Mn: 0.3%-0.5%, Ti: 0.2%-0.4%, Li: 0.4%-0.6%, alumina nanoparticles: 0.1%-0.3%, boron nitride nanofibers 0.18%-0.6%, impurity elements ≤0.1%, and the balance is Al.

2. The high-toughness and bending-resistant aluminum alloy material according to claim 1, characterized in that: The diameter of the boron nitride nanofiber is 20-100 nm.

3. The high-toughness and bending-resistant aluminum alloy material according to claim 1, characterized in that: The particle size of the aluminum oxide nanoparticles is 30-60 nm.

4. The high-toughness and bending-resistant aluminum alloy material according to claim 1, characterized in that: The mass ratio of the aluminum oxide nanoparticles to the boron nitride nanofibers is 1:1.5-2.

5.

5. The high-toughness and bending-resistant aluminum alloy material according to claim 1, characterized in that: The mass ratio of the total mass of the aluminum oxide nanoparticles and the boron nitride nanofibers to the mass of Li is 0.7-1.5:

1.

6. A method for preparing the high-toughness and bending-resistant aluminum alloy material according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Stir and mix lithium powder and boron nitride nanofibers, put them into a smelting furnace under an inert atmosphere to heat and melt, and after the lithium powder is completely melted, add alumina nanoparticles and stir and mix them evenly; Step 2: Heat the smelting furnace to 750-780°C, put in zinc ingots, magnesium ingots and aluminum ingots, and use argon gas protection during the smelting process until the metal is completely melted; Step 3: After melting, keep the temperature for 20-30 minutes and then raise the temperature to 950-1000°C, add manganese ingots and titanium ingots, and obtain aluminum alloy solution after the metal is completely melted; Step 4: Cool the aluminum alloy solution and then vacuum cast it to obtain an aluminum alloy ingot. After solution treatment, perform graded artificial aging treatment and naturally cool it to room temperature to obtain a high-toughness and bending-resistant aluminum alloy material.

7. The method for preparing a high-toughness and bending-resistant aluminum alloy material according to claim 6, characterized in that: The inert atmosphere is one of argon, helium, neon, xenon and nitrogen.

8. The method for preparing a high-toughness and bending-resistant aluminum alloy material according to claim 6, characterized in that: The purity of the lithium powder, zinc ingot, magnesium ingot, aluminum ingot, manganese ingot and titanium ingot is ≥99.9%.

9. The method for preparing a high-toughness and bending-resistant aluminum alloy material according to claim 6, characterized in that: The steps of the solution treatment are: heating the aluminum alloy ingot to 450-500° C. and keeping the temperature for 6-10 hours, and cooling to room temperature by water quenching or air cooling.

10. The method for preparing a high-toughness and bending-resistant aluminum alloy material according to claim 6, characterized in that: The initial aging temperature of the graded artificial aging treatment is 120-130° C., the duration is 3-5 hours, and the subsequent aging temperature is 150-160° C., the duration is 4-6 hours.