High-toughness aluminum-lithium alloy and preparation method thereof

Abstract

The invention discloses a high-toughness aluminum-lithium alloy and a preparation method, and belongs to the field of metal material processing technologies, and the preparation method comprises the following steps: carrying out solution treatment on an annealed aluminum-lithium alloy, then carrying out 3-5% of pre-deformation, then carrying out low-temperature pre-aging on the pre-deformed aluminum-lithium alloy, then adding 1-8% of intermediate secondary deformation, then carrying out high-temperature aging, and finally carrying out high-temperature aging treatment on the pre-deformed aluminum-lithium alloy to obtain the high-toughness aluminum-lithium alloy. And cooling to room temperature to obtain the high-toughness aluminum-lithium alloy. According to the method, dislocation configuration of the aluminum-lithium alloy is uniform and compact through a two-stage stretching heat treatment (TTIA) process, precipitation strengthening of a T1 phase is promoted, and alloy weak points are pinned, so that plasticity is improved while the strength of the aluminum-lithium alloy is greatly improved, and synergistic growth of the strength and plasticity of the alloy is achieved; the aluminum-lithium alloy treated by the method is high in strength and good in plasticity, and can meet the performance requirements of the fields of aerospace, automobile manufacturing and the like on structural materials in the national industrialization process.

Description

Technical Field

[0001] This invention relates to the fields of metal material deformation technology and heat treatment technology, specifically to a high-strength and high-toughness aluminum-lithium alloy and its preparation method. Background Technology

[0002] With the accelerated advancement of China's new industrialization and the rapid development of fields such as aerospace and automobile manufacturing, higher demands are being placed on the lightweighting of structural components. Aluminum-lithium alloys, due to their higher specific strength and specific stiffness compared to traditional aluminum alloys, can significantly reduce the weight of structural components while maintaining stiffness. They also possess excellent corrosion resistance and mechanical properties, making them widely used in aerospace, automobile manufacturing, and electronic equipment industries. The third-generation advanced aluminum-lithium alloy, represented by 2195, involves controlling the ratio of Cu and Li elements in the alloy and adding Mg, Ag, and Zr elements for microalloying, resulting in a significant precipitation strengthening effect. 2195 aluminum-lithium alloy sheets, due to their low density, high strength, and good corrosion resistance, have been successfully used in the bottom of launch vehicle propellant tanks and the skin of the C919 passenger aircraft.

[0003] The strengthening of aluminum-lithium alloys mainly relies on solid solution strengthening and age hardening, with the strengthening effect stemming from the hindering effect of the internal structure on dislocation slip. The main strengthening phases in aluminum-lithium alloys are the T1 phase, δ′ phase, and θ′ phase. Among them, the T1 phase consists of disk-shaped hard particles, and its dislocation action mechanism is a bypass mechanism, and it is located in the matrix {111} Al Precipitation on crystal planes results in a more significant strengthening effect. Therefore, the strengthening and toughening of aluminum-lithium alloys is mainly achieved by controlling the T1 phase in the microstructure through various processes. The T1 phase exhibits a strong dependence on the nucleation of defects such as dislocations. Therefore, in industry, pre-deformation is often used to introduce dislocations into aluminum-lithium alloys to promote the nucleation of the T1 phase during aging, thereby improving performance. Pre-stretching deformation is often used to accelerate the aging precipitation of aluminum-lithium alloy sheets. However, simple pre-stretching deformation faces the problem of difficulty in adjusting the dislocation density and uniformity. Small pre-stretching deformation introduces low dislocation density, resulting in limited strengthening of the alloy. On the other hand, excessive pre-stretching deformation leads to the concentration of dislocations at grain boundaries, uneven precipitation of the T1 phase, and a decrease in alloy plasticity.

[0004] Therefore, in order to achieve the toughness and strength of aluminum-lithium alloys, there is an urgent need for a new, simple, effective and easy-to-implement process to control the dislocation configuration and T1 phase aging precipitation behavior in order to improve the comprehensive mechanical properties of aluminum-lithium alloys. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a high-strength and high-toughness aluminum-lithium alloy and its preparation method. This preparation method improves the comprehensive mechanical properties of the aluminum-lithium alloy by controlling the dislocation configuration and the T1 phase aging precipitation behavior. This invention is achieved through the following technical solutions: A method for preparing a high-strength and high-toughness aluminum-lithium alloy includes the following steps: After solution treatment of annealed aluminum-lithium alloy, 3-5% pre-deformation is performed. Then, the pre-deformed aluminum-lithium alloy is pre-aged at low temperature. After adding 1-8% intermediate secondary tensile deformation, it is aged at high temperature and cooled to room temperature to obtain an aluminum-lithium alloy with high strength and toughness ratio.

[0006] Preferably, the pre-deformation treatment is a pre-stretching process.

[0007] Preferably, the solution treatment temperature is 510±5℃ and the holding time is 2 h.

[0008] Preferably, the quenching method is water quenching, the quenching medium is room temperature water, and the quenching transfer time is ≤5 s.

[0009] Preferably, the low-temperature pre-aging treatment temperature is 120±5℃, and the holding time is 12 h.

[0010] Preferably, the intermediate secondary stretching deformation treatment is a stretching process.

[0011] Preferably, the high-temperature aging treatment temperature is 175±5℃, and the holding time is 24 h.

[0012] A method for preparing a high-strength and high-toughness aluminum-lithium alloy, wherein the microstructure of the aluminum-lithium alloy includes a second phase and a T1 phase, and the T1 phase is semi-coherent with the aluminum matrix.

[0013] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a method for preparing a high-strength and high-toughness aluminum-lithium alloy. The method involves a comprehensive deformation process combining pre-stretching and intermediate secondary stretching deformation during aging. This introduces a large number of dislocations into the solution-treated alloy, ensuring both high dislocation density and uniform dislocation distribution. The two-stage tensile interruption aging (TTIA) process is a composite heat treatment process consisting of pre-stretching, pre-aging, intermediate secondary stretching, and high-temperature aging. Pre-stretching provides favorable nucleation conditions for the T1 precursor phase during subsequent low-temperature pre-aging and, together with intermediate stretching deformation, provides numerous nucleation sites for the main strengthening phase, T1, during the subsequent high-temperature aging process. Simultaneously, the secondary stretching process added during aging effectively controls the density uniformity of dislocations and allows for repeated dislocation multiplication at easily slipping locations in the alloy, compensating for dislocations annihilated during low-temperature pre-aging. It also introduces a large number of T1 phase nucleation sites at defect-prone areas, ensuring the precipitation of a large amount of dense and uniform T1 phase along weak points such as alloy defects during the subsequent high-temperature aging process, thereby controlling the overall mechanical properties of the alloy. As the amount of intermediate tensile deformation increases, the alloy properties first improve and then decrease. The alloy with 4% intermediate secondary tensile deformation achieves optimal strength and toughness. Compared with the T8 state alloy that undergoes pre-stretching after solution treatment and direct aging, the treatment process described in this invention, which involves pre-stretching after solution treatment and adding intermediate secondary stretching during the two-stage aging process, can increase the density and reduce the size of the T1 phase in the aluminum-lithium alloy, thereby effectively improving the overall mechanical properties of the alloy.

[0014] Furthermore, before pre-deforming the aluminum-lithium alloy, it undergoes solution treatment to eliminate its texture and ensure isomorphism. After solution treatment, the aluminum-lithium alloy is immediately clamped and quickly placed into a quenching tank. The quenching medium is room temperature water, and the quenching transfer time is ≤5 s. Ensuring a short quenching transfer time accurately preserves the atoms of each element in the solution treatment, maintaining the alloy microstructure in a supersaturated solution state and effectively preventing the segregation of solute atoms and the precipitation of non-target precipitates during the slow temperature decrease process. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the aluminum-lithium alloy preparation method of the present invention; Figure 2 This is an engineering stress-strain curve of the aluminum-lithium alloy of the present invention; Figure 3 The aluminum-lithium alloy structure of this invention

[110] Al Transmission electron microscope image under rotating axis; Among them, (a) is the HAADF diagram of the T8 state alloy microstructure, (b) is the BF diagram of the T8 state alloy microstructure, (c) is the high-resolution diagram of the T8 state alloy microstructure; (d) is the HAADF diagram of the aluminum-lithium alloy microstructure treated with low temperature pre-aging + 4% intermediate secondary tensile deformation + high temperature aging, (e) is the BF diagram of the aluminum-lithium alloy microstructure treated with low temperature pre-aging + 4% intermediate secondary tensile deformation + high temperature aging, and (f) is the high-resolution diagram of the aluminum-lithium alloy microstructure treated with low temperature pre-aging + 4% intermediate secondary tensile deformation + high temperature aging. Figure 4 This is a statistical result diagram of the radius and thickness of the T1 phase, the strengthening phase precipitated in the aluminum-lithium alloy of the present invention.

[0017] Among them, (a) is a statistical diagram of the radius distribution of the strengthening phase T1 in the T8 state alloy and the aluminum-lithium alloy treated with low temperature pre-aging + 4% intermediate secondary tensile deformation + high temperature aging, and (b) is a statistical diagram of the thickness of the strengthening phase T1 in the T8 state alloy and the aluminum-lithium alloy treated with low temperature pre-aging + 4% intermediate secondary tensile deformation + high temperature aging. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] A high-strength and high-toughness aluminum-lithium alloy, whose {111} Al The surface forms a disc-shaped T1 phase and a granular second phase.

[0021] The T1 phase is semi-coherent with the Al matrix, and the (0001) plane of the T1 phase is parallel to the (111) plane of the Al matrix. It is the most important strengthening phase in aluminum-lithium alloys and is usually

[110] . AlUnder rotating conditions, obvious needle-like bright lines are observed. During the process control, both heat treatment and deformation processes promote the precipitation of the T1 phase, thereby improving the strength and plasticity of the alloy. In particular, the high-temperature aging treatment produces a large amount of T1 phase precipitation, while the TTIA comprehensive treatment process significantly promotes the nucleation of the T1 phase at weak points in the alloy.

[0022] Regarding the aforementioned high-strength and high-toughness aluminum-lithium alloy, this application also provides a method for preparing the high-strength and high-toughness aluminum-lithium alloy, comprising the following steps: Step 1: The annealed aluminum-lithium alloy is solution treated and then water quenched.

[0023] The solution treatment temperature is 510±5℃, and the holding time is 2 h; It should be noted that the mass percentage of each element in the annealed aluminum-lithium alloy is as follows: Cu - 3.91%, Li - 0.94%, Mg - 0.57%, Ag - 0.42%, Zr - 0.12%, with the balance being Al. The thickness of the annealed aluminum-lithium alloy is 2 mm. The quenching method is water quenching, the quenching medium is room temperature water, and the quenching transfer time is ≤5 s.

[0024] Step 2: Perform pre-deformation treatment on the aluminum-lithium alloy obtained in Step 1, and then perform low-temperature pre-aging treatment.

[0025] The pre-deformation treatment is a pre-stretching process, with a stretching deformation of 3-5%; It should be noted that the aluminum-lithium alloy after solution treatment is isotropic. The tensile direction of the deformation treatment can be along the rolling direction or perpendicular to the rolling direction. In this invention, the tensile deformation is uniformly performed along the rolling direction, and the tensile deformation is processed by a universal testing machine. The low-temperature pre-aging treatment was performed at a temperature of 120±5℃ for 12 hours.

[0026] Step 3: Perform intermediate deformation treatment on the aluminum-lithium alloy obtained in Step 2, and then perform high-temperature aging treatment to obtain a high-strength and high-toughness aluminum-lithium alloy.

[0027] The intermediate deformation process is a stretching process, with a stretching deformation amount of 1-8%; The high-temperature aging treatment temperature is 175±5℃, and the holding time is 24 h; It should be noted that during the solution treatment and aging treatment, the aluminum-lithium alloy at room temperature is directly placed into the heated muffle furnace, and removed after the set time is reached, without being heated or cooled with the furnace.

[0028] Example 1 Taking annealed 2195 aluminum-lithium alloy sheet as an example, the preparation method of a high-strength and high-toughness aluminum-lithium alloy of this application is described in detail, including the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 505℃ for 2 hours for solution treatment. Then immediately clamp and remove the sample, and quench it in room temperature water, controlling the quenching transfer temperature to ≤5 s.

[0029] Step 2: The solution-quenched 2195 aluminum-lithium alloy is pre-stretched by 4%. Then, the pre-stretched 2195 aluminum-lithium alloy is placed in a muffle furnace at 115°C and held for 12 hours for low-temperature pre-aging treatment. The 2195 aluminum-lithium alloy is then clamped and taken out and air-cooled to room temperature.

[0030] Step 3: Perform a secondary tensile deformation treatment on the 2195 aluminum-lithium alloy after low-temperature pre-aging treatment. The secondary tensile amount is 1%. Then, place the 2195 aluminum-lithium alloy after secondary tensile deformation treatment into a muffle furnace at 170℃ and keep it at 170℃ for 24 hours for high-temperature aging treatment. Then, clamp the sample and take it out, and air cool it to room temperature.

[0031] Example 2 A detailed method for preparing a high-strength and high-toughness aluminum-lithium alloy is provided, including the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 515℃ for 2 hours for solution treatment. Then immediately clamp and remove the sample, and quench it in room temperature water, controlling the quenching transfer temperature to be ≤5 s.

[0032] Step 2: The solution-quenched 2195 aluminum-lithium alloy is pre-stretched by 3%. Then, the pre-stretched 2195 aluminum-lithium alloy is placed in a muffle furnace at 120°C and held for 12 hours for low-temperature pre-aging treatment. The sample is then clamped and taken out and air-cooled to room temperature.

[0033] Step 3: Perform a secondary tensile deformation treatment on the 2195 aluminum-lithium alloy after low-temperature pre-aging treatment. The secondary tensile amount is 2%. Then, place the aluminum-lithium alloy after intermediate tensile deformation treatment into a muffle furnace at 175℃ and keep it at 175℃ for 24 hours for high-temperature aging treatment. Then, clamp the sample and take it out, and air cool it to room temperature.

[0034] Example 3 A detailed method for preparing a high-strength and high-toughness aluminum-lithium alloy is provided, including the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 515℃ for 2 hours for solution treatment. Then immediately clamp and remove the sample, and quench it in room temperature water, controlling the quenching transfer temperature to be ≤5 s.

[0035] Step 2: The solution-quenched 2195 aluminum-lithium alloy was pre-stretched by 3%. The pre-stretched aluminum-lithium alloy was then placed in a muffle furnace at 125°C and held for 12 hours for low-temperature pre-aging treatment. The sample was then clamped and removed and air-cooled to room temperature.

[0036] Step 3: Perform a secondary tensile deformation treatment on the 2195 aluminum-lithium alloy after low-temperature pre-aging treatment. The secondary tensile amount is 4%. Then, place the aluminum-lithium alloy after intermediate tensile deformation treatment into a muffle furnace at 180℃ and keep it at 180℃ for 24 hours for high-temperature aging treatment. Then, clamp the sample and take it out, and air cool it to room temperature.

[0037] Example 4: A detailed method for preparing a high-strength and high-toughness aluminum-lithium alloy is provided, including the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 510℃ and hold for 2 hours for solution treatment. Then immediately clamp and remove the 2195 aluminum-lithium alloy and quench it in room temperature water, controlling its quenching transfer temperature to ≤5 s.

[0038] Step 2: The solution-quenched 2195 aluminum-lithium alloy was pre-stretched by 4%. The pre-stretched aluminum-lithium alloy was then placed in a muffle furnace at 115°C and held for 12 hours for low-temperature pre-aging treatment. The sample was then clamped and removed and air-cooled to room temperature.

[0039] Step 3: Perform a secondary tensile deformation treatment on the 2195 aluminum-lithium alloy after low-temperature pre-aging treatment. The secondary tensile amount is 6%. Then, place the aluminum-lithium alloy after intermediate tensile deformation treatment into a muffle furnace at 180℃ and keep it at 180℃ for 24 hours for high-temperature aging treatment. Then, clamp the sample out and air cool it to room temperature.

[0040] Example 5: A detailed method for preparing a high-strength and high-toughness aluminum-lithium alloy is provided, including the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 505℃ and hold for 2 hours for solution treatment. Then immediately clamp and remove the 2195 aluminum-lithium alloy and quench it in room temperature water, controlling its quenching transfer temperature to ≤5 s.

[0041] Step 2: The solution-quenched 2195 aluminum-lithium alloy is pre-stretched by 5%. The pre-stretched aluminum-lithium alloy is then placed in a muffle furnace at 115°C and held for 12 hours for low-temperature pre-aging treatment. The sample is then clamped and taken out and air-cooled to room temperature.

[0042] Step 3: Perform a secondary tensile deformation treatment on the 2195 aluminum-lithium alloy after low-temperature pre-aging treatment. The secondary tensile amount is 8%. Then, place the aluminum-lithium alloy after intermediate tensile deformation treatment into a muffle furnace at 170℃ and keep it at 170℃ for 24 hours for high-temperature aging treatment. Then, clamp the sample out and air cool it to room temperature.

[0043] Comparative example: The difference between this comparative example and Examples 1-5 is that the pre-stretched 2195 aluminum-lithium alloy is not subjected to low-temperature pre-aging treatment and secondary tensile deformation treatment during the preparation process of this example, while the rest of the process is the same.

[0044] A method for preparing a high-strength and high-toughness aluminum-lithium alloy includes the following steps: Step 1: Place the annealed 2195 aluminum-lithium alloy in a muffle furnace at 510℃ and hold for 2 hours for solution treatment. Then immediately clamp and remove the 2195 aluminum-lithium alloy and quench it in room temperature water, controlling its quenching transfer temperature to ≤5 s.

[0045] Step 2: The solution-quenched 2195 aluminum-lithium alloy was pre-stretched by 4%. The pre-stretched aluminum-lithium alloy was then placed in a muffle furnace at 175°C and held for 24 hours for aging treatment. The sample was then clamped and removed and air-cooled to room temperature.

[0046] See Figure 1 This is a flowchart of a method for preparing a high-strength and high-toughness aluminum-lithium alloy according to the present invention. The solution treatment process parameters are 510℃ / 2 h, followed by quenching in water at room temperature, and then 3-5% pre-stretch deformation treatment. Subsequently, the comparative examples are aged according to the single-peak aging process parameters: 175℃ / 24 h + air cooling. Examples 1-5 are aged according to the double-peak aging process parameters: 120℃ / 12 h + 175℃ / 24 h + air cooling. A secondary tensile deformation is added between the two-stage aging processes, with elongation amounts of 1%, 2%, 4%, 6%, and 8% of the gauge length of the standard tensile specimen, respectively.

[0047] Example 6 Application of a high-strength and high-toughness aluminum-lithium alloy in aerospace components, automotive components or electronic devices.

[0048] Mechanical properties of the 2195 aluminum-lithium alloys prepared by the processes of Examples 1-5 and the comparative example were tested.

[0049] 1. Hardness test The hardness of the 2195 aluminum-lithium alloys prepared in Examples 1-5 and the comparative example was tested using a Buehler Wilson VH3100 Vickers microhardness tester. The loading load was 150 g, and the loading time was 10 s. Nine points were marked on each sample, and the average value was taken. The test results are shown in Table 1.

[0050] 2. Tensile property test Room temperature uniaxial tensile tests were conducted on the 2195 aluminum-lithium alloys prepared by the processes in Examples 1-5 and the comparative example on an MTS universal testing machine to test their tensile properties. Before the tensile tests, the standard tensile specimens of the 2195 aluminum-lithium alloys prepared by each process needed to be polished to remove the oxide layer and machining wire cutting marks on the surface, obtaining clean and smooth specimens. The tensile rate was 0.06 mm / s, and three samples were taken for each state, with the average value taken. The displacement and load curves measured in the tensile tests were plotted using Origin software. The yield strength, tensile strength, and elongation of the specimens were obtained by measurement. The test results are shown in Table 1.

[0051] Table 1

[0052] Table 1 shows the Vickers hardness, yield strength, tensile strength, and elongation of the comparative examples and Examples 1-5. As can be seen from Table 1, the T8 state 2195 aluminum-lithium alloy shown in the comparative examples has a relatively high hardness, but its strength and elongation are both relatively low. After adding low-temperature pre-aging treatment, the hardness of the 2195 aluminum-lithium alloy shown in Example 1 decreased, but its strength and elongation both increased. With the addition of intermediate tensile deformation in the two-stage aging process, from 1% (Example 1), 2% (Example 2), 4% (Example 3), 6% (Example 4), and 8% (Example 5), the yield strength, tensile strength, and elongation of the aluminum-lithium alloy all showed a trend of first increasing and then decreasing. The addition of 4% intermediate tensile deformation in the two-stage aging process (Example 3) showed the most significant performance optimization for the 2195 aluminum-lithium alloy, increasing the yield strength to 534.67 MPa, the tensile strength to 604.99 MPa, and the elongation to 4.38%. In summary, the preparation method of 2195 aluminum-lithium alloy described in this invention can significantly improve the strength of 2195 aluminum-lithium alloy while greatly enhancing its plasticity, thereby optimizing the overall mechanical properties of the alloy.

[0053] Figure 2 The above comparative examples and Example 3 show the engineering stress-strain curves. From... Figure 2As can be seen, the yield strength and tensile strength of the T8 state 2195 aluminum-lithium alloy are not high, and its plasticity is also poor. After adding 4% intermediate tensile deformation (Example 3) during the two-stage aging process, the yield strength and tensile strength of the 2195 aluminum-lithium alloy are improved, reaching 104% and 106% of the comparative strength, respectively. At the same time, the elongation is significantly improved, reaching 166% of the comparative elongation. Therefore, the method for preparing a high-strength and high-toughness aluminum-lithium alloy described in this invention, through the combination of two-stage aging treatment and intermediate tensile deformation treatment, can significantly improve the strength of the 2195 aluminum-lithium alloy while improving its plasticity, achieving a synergistic increase in the alloy's strength and toughness.

[0054] Figure 3 For the comparative examples and Example 3 described above, in

[110] Al High-angle annular dark-field imaging, bright-field images, and high-resolution images using transmission electron microscopy under rotating axis. From Figure 3 It can be seen that in the 2195 aluminum-lithium alloy in the simple T8 state (comparative example) and the two-stage aging process with an added intermediate tensile deformation of 4% (Example 3), dislocations multiply and become entangled in large quantities, and the main precipitated phase in the microstructure is a large number of needle-like and lamellar T1 phases. In the 2195 aluminum-lithium alloy after two-stage aging and the addition of 4% intermediate secondary tensile deformation, the T1 phase is uniform and dense, and its size and thickness are smaller. Figure 3 (a) and Figure 3 As shown in (d), the 2195 aluminum-lithium alloy after two-stage aging and the addition of 4% intermediate deformation exhibits a denser distribution of the T1 phase compared to the T8 state alloy. This is mainly due to the introduction of a large number of T1 phase nucleation sites by the TTIA synthesis process. Pre-stretching initially introduces a large number of dislocation nucleation sites into the alloy, low-temperature pre-aging restores dislocations to achieve uniform distribution, and during aging, a large number of dispersed δ′ phases are initially formed at the dislocation nucleation sites as T1 precursor phases to promote the nucleation of subsequent T1 phases. Intermediate stretching deformation further adds a large number of dislocations at easily slipped locations, facilitating the uniform and dense precipitation of the T1 phase during subsequent high-temperature aging and providing a pinning effect on defects in the alloy. (Refer to...) Figure 3 (b) and Figure 3 (e) The dislocation distribution in the corresponding microstructure shows that the dislocations in the 2195 aluminum-lithium alloy, after double-stage aging and the addition of 4% intermediate secondary tensile deformation, are more concentrated and uniformly distributed. Therefore, the preparation method of the high-strength and high-toughness aluminum-lithium alloy described in this invention can effectively control the radius, thickness, and distribution configuration of the precipitated phases in the alloy, thereby controlling the comprehensive mechanical properties of the alloy.

[0055] Figure 4 The statistical data on the radius and thickness of the T1 precipitate in the comparative examples and Example 3 above are provided. This visually demonstrates that after pre-stretching + low-temperature pre-aging + 4% intermediate tensile deformation + high-temperature aging treatment (TTIA process), the grain size distribution of the main strengthening phase, T1, in the 2195 aluminum-lithium alloy is significantly improved. From... Figure 4As can be seen in (a), the radius of the main precipitated strengthening phase T1 in the T8 alloy (comparative example) is mainly distributed in the range of 40-90 nm, with very few precipitates having a radius less than 20 nm, and a small number of T1 precipitates having a radius exceeding 100 nm, with an average T1 phase radius of 68.26 nm; while in the alloy with 4% intermediate tensile deformation added during double-stage aging (Example 3), the radius of the main precipitated strengthening phase T1 is mainly distributed in the range of 20-50 nm, with very few precipitates having a radius less than 10 nm, and a small number of T1 precipitates having a radius exceeding 60 nm, with an average T1 phase radius of 34.02 nm. Figure 4 As shown in (b), the average thickness of the precipitation-strengthened T1 phase in the T8 state alloy (comparative example) is 1.77 nm, while the thickness of the T1 phase in the alloy with 4% intermediate tensile deformation added during two-stage aging (Example 3) is reduced to 1.21 nm, with smaller error bars and uniform T1 phase lamellar thickness. Therefore, the TTIA comprehensive treatment method of the preparation method of a high-strength and tough aluminum-lithium alloy described in this invention can effectively control the radius and thickness of the precipitated phase in 2195 aluminum-lithium alloy, thereby controlling the mechanical properties of the alloy.

[0056] In summary, this invention, through the TTIA (Temperature-to-Intensity Interval) deformation heat treatment process, introduces a large number of dense and uniform T1 phase nucleation sites into the solution-treated alloy, providing favorable precipitation conditions for the primary T1 phase strengthening. Simultaneously, the two-stage tensile heat treatment process guides the precipitation of a large amount of T1 phase at the alloy's slip-prone weak points for strengthening. This results in a continuous increase in strength and plasticity of the 2195 aluminum-lithium alloy under the combined effects of precipitation strengthening and deformation strengthening, achieving a balance between strength and toughness, and resulting in excellent overall alloy performance. Furthermore, this invention provides a simple and low-cost method for preparing a high-strength and high-toughness aluminum-lithium alloy, which can meet the needs of the wide application of aluminum-lithium alloys in various industrial fields.

[0057] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a high-strength and high-toughness aluminum-lithium alloy, characterized in that, Includes the following steps: Step 1: Perform solution treatment on the annealed aluminum-lithium alloy; Step 2: Perform pre-deformation treatment on the aluminum-lithium alloy obtained in Step 1, and then perform pre-aging treatment; The deformation amount of the pre-deformation treatment is 3-5%; Step 3: Perform intermediate deformation treatment on the aluminum-lithium alloy obtained in Step 2, and then perform secondary aging treatment to obtain a high-strength and high-toughness aluminum-lithium alloy. The deformation amount of the secondary deformation process is 1-8%; The temperature of the secondary aging treatment is higher than the temperature of the pre-aging treatment.

2. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 1, characterized in that, Step 1 also includes performing a solution treatment on the annealed aluminum-lithium alloy, followed by a water quenching treatment.

3. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 2, characterized in that, The quenching method is water quenching, the quenching medium is room temperature water, and the quenching transfer time is ≤5 s.

4. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 1, characterized in that, The solution treatment in step 1 is performed at a temperature of 510±5℃ for 2 hours.

5. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 1, characterized in that, The pre-deformation process and the secondary deformation process are tensile deformations.

6. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 1, characterized in that, The pre-aging treatment in step 2 is performed at a temperature of 120±5℃ for 12 hours.

7. The method for preparing a high-strength and high-toughness aluminum-lithium alloy according to claim 1, characterized in that, The secondary aging treatment temperature is 175±5℃, and the holding time is 24 h.

8. A high-strength and high-toughness aluminum-lithium alloy prepared by the preparation method according to any one of claims 1-7, characterized in that, It includes a T1 phase and a second phase, the T1 phase being semi-coherent with the Al matrix.

9. A high-strength and high-toughness aluminum-lithium alloy according to claim 8, characterized in that, The second phase is granular, the T1 phase is disc-shaped, and the (0001) plane of the T1 phase is parallel to the (111) plane of the Al matrix.

10. The application of a high-strength and high-toughness aluminum-lithium alloy in aerospace components, automotive components or electronic devices.

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