A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy

Abstract

This invention discloses a method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy, belonging to the technical field of high-strength, high-toughness aluminum alloy preparation. This invention optimizes the alloy composition by adding Sc, Zr, Pr, and Tb elements, and combines this with processes such as plasma inert gas atomization, pressing, sintering, high-temperature solution treatment and quenching cycles, aging, asynchronous rolling and cryogenic cycles, and isothermal vacuum treatment to achieve optimal strength and toughness in the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy. On the one hand, the addition of rare-earth elements refines the grain size of the alloy, suppressing the appearance of coarse grains and promoting the formation of a strong and tough texture. On the other hand, specific high-temperature solution treatment, solution time, quenching, asynchronous rolling + cryogenic treatment cycles, and isothermal vacuum treatment processes ensure the formation of a [1,0,0] texture with preferred orientation.

Description

Technical Field

[0001] This invention belongs to the field of high-strength and high-toughness aluminum alloy preparation technology, specifically relating to a method for preparing a high-strength and high-toughness textured rare-earth aluminum-lithium-copper alloy. Background Technology

[0002] Aluminum-lithium alloys possess advantages such as lightweight, high strength, corrosion resistance, and good machinability, making them suitable for applications in aerospace, automotive, and marine engineering. However, the development of modern industry has placed higher demands on the strength and toughness of aluminum-lithium alloys.

[0003] Invention patent CN116179912A discloses a Ce-containing high-strength and high-toughness aluminum-lithium alloy and its preparation method. By adding trace amounts of rare earth element Ce, a uniform grain size with an average grain size of less than 136 μm is obtained through alloying. This fine grain increases the strengthening effect, improves the alloy strength, and reduces the anisotropy of the high-strength aluminum-lithium alloy. After a series of heat treatments, high strength and elongation can be obtained, with a strength higher than 530 MPa and an elongation greater than 16%. The resulting aluminum-lithium alloy forged plate has low anisotropy, and its transverse and longitudinal tensile strength and yield strength deviation is less than 3%.

[0004] The aluminum alloys obtained through the above processes, by adding rare earth elements and undergoing heat treatment to form different microstructures, improve the alloy's strength, tensile strength, and formability. However, the improvement in strength and toughness is not ideal. Therefore, it is necessary to provide a processing technology to improve the strength and toughness of aluminum-lithium alloys, further expanding the application of aluminum-lithium alloy materials in aerospace, automotive, and marine engineering fields. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy. This invention aims to improve the strength and toughness of the aluminum-lithium alloy by adding Sc, Zr, Pr, and Tb elements, and employing plasma inert gas atomization, pressing, sintering, high-temperature solution treatment and quenching cycles, aging, asynchronous rolling and deep cryogenic cycling, and isothermal vacuum treatment.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy involves optimizing the alloy composition by adding Sc, Zr, Pr, and Tb elements. This is combined with processes such as plasma inert gas atomization, pressing, sintering, high-temperature solution treatment and quenching cycles, aging, asynchronous rolling and deep cryogenic cycling, and isothermal vacuum treatment to achieve optimal strength and toughness in the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy. The method includes the following steps:

[0008] (1) The rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials are respectively subjected to plasma inert gas atomization treatment and mixed. Then, the two are thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again.

[0009] (2) Press the powder obtained in step (1) into a blank;

[0010] (3) Microwave sinter the blank, then perform solution treatment and quenching cycle three times, and finally pre-aging treatment.

[0011] (4) The pre-aged alloy shall be subjected to asynchronous rolling and deep cryogenic cycling treatment for no less than 4 times;

[0012] (5) A high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy was obtained after constant temperature vacuum treatment.

[0013] The high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy comprises the following components by mass percentage: 0.8–1.1% Li, 3.7–4.2% Cu, 0.7–1.0% Sc, 0.02–0.04% Zr, 0.01–0.03% Pr, 0.01–0.02% Tb, with the balance being Al and unavoidable impurities. Compared to ordinary aluminum-lithium-copper alloys, this invention, by adding trace amounts of Sc, Zr, Pr, and Tb, can refine the grain size and facilitate the generation of a strong and tough texture during subsequent processing.

[0014] In a preferred embodiment of the present invention, the process parameters for the plasma inert gas atomization treatment are as follows: DC plasma gun power is 20–40 kW, the inert gas is argon, and the muzzle flow rate is controlled at 100–110 L / min. The material obtained by the plasma inert gas atomization method of the present invention has high sphericity and low impurity content.

[0015] In a preferred embodiment of the present invention, in step (2), the pressing pressure is 200 MPa and the holding time is 10 min.

[0016] In a preferred embodiment of the present invention, the microwave sintering temperature is 580°C, the heating rate is 50°C / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5~5.5kW, and the atmosphere is argon.

[0017] As a preferred embodiment of the present invention, the solution and quenching cycle treatment is carried out three times as follows: the initial solution temperature is 480°C, the solution temperature increases by 25°C in each cycle, the solution time in each cycle is 30 min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil, respectively.

[0018] By using different quenching media in three cycles, the plasticity and strength of the alloy are enhanced through the synergistic effect of controlling the cooling rate and multi-stage solid solution treatment.

[0019] CL-1 organic quenching agent is a solution of mineral oil composed of salts such as NaCl and KCl.

[0020] In a preferred embodiment of the present invention, the pre-aging treatment is performed at a temperature of 80-100°C for 30 minutes.

[0021] As a preferred embodiment of the present invention, the asynchronous rolling and cryogenic cycle treatment specifically includes: the initial speed ratio of asynchronous rolling is 1.4 to 1.7, the initial reduction is 24%, the reduction is reduced by 4 to 6% and the speed ratio is reduced by 0.1 to 0.2 in each cycle, and the cryogenic time in each cycle is 20 to 30 minutes.

[0022] In a preferred embodiment of the present invention, the total reduction of the asynchronous rolling and cryogenic cycling treatment is 65-74%. The present invention uses more than four asynchronous rolling and cryogenic cycling treatments to ensure sufficient grain refinement of the alloy, resulting in a stronger and tougher texture in subsequent processes.

[0023] This invention prevents the alloy from recovering after cold deformation by deep cryogenic treatment after asynchronous rolling, retains the deformation energy stored after cold deformation, and promotes the formation of a strong texture during the recrystallization process of isothermal vacuum treatment.

[0024] As a preferred embodiment of the present invention, the temperature of the constant temperature vacuum treatment is 15-25°C and the time is 30 minutes. The constant temperature vacuum treatment is beneficial to obtaining a [1,0,0] texture with high strength and high toughness.

[0025] This invention utilizes a constant-temperature vacuum treatment followed by high-temperature solution treatment and quenching cycle treatment, asynchronous rolling and cryogenic cycle treatment, to recrystallize and form a strong [1,0,0] texture. This avoids the problem that traditional constant-temperature treatment would cause the texture to rearrange through recrystallization, thus reducing the strength and plasticity of the alloy.

[0026] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention obtains a high-strength, high-toughness aluminum-lithium-copper alloy with the desired strong and tough texture by adding specific rare earth elements Sc, Zr, Pr, and Tb, combined with processes such as ion inert gas atomization, pressing, sintering, high-temperature solution treatment and quenching cycle treatment, asynchronous rolling and cryogenic cycle treatment, and isothermal vacuum treatment. Compared with conventional aluminum-lithium-copper alloy production processes, on the one hand, the addition of rare earth elements refines the grain size of the alloy, inhibits the appearance of coarse grains, and promotes the formation of a strong and tough texture. On the other hand, the specific high-temperature solution treatment, solution time, quenching, asynchronous rolling + cryogenic treatment cycle treatment, and isothermal vacuum treatment processes work synergistically to ensure the formation of a [1,0,0] texture with preferred orientation. Attached Figure Description

[0027] Figure 1 A process flow diagram for the preparation of high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloys. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0029] Example 1

[0030] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0031] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 1, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 30kW, inert gas of argon, and nozzle flow rate of 100L / min.

[0032] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0033] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0034] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0035] (5) Pre-aging treatment: Pre-aging treatment at 90℃ for 30 min.

[0036] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling five times: the initial speed ratio of asynchronous rolling was 1.6, the initial reduction was 24%, the reduction was reduced by 5% and the speed ratio was reduced by 0.2 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0037] (7) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 2.

[0038] Table 1. Chemical composition (wt%) of high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloys according to embodiments of the present invention.

[0039]

[0040] Table 2

[0041] Yield strength / MPa Tensile strength / MPa elongation 410 500 24％

[0042] Example 2

[0043] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0044] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 3, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 20kW, inert gas of argon, and nozzle flow rate of 110L / min.

[0045] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0046] (3) The blank is placed in a microwave sintering furnace and heated for sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5kW, and the atmosphere is argon.

[0047] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0048] (5) Pre-aging treatment: Pre-aging treatment at 80℃ for 30 min.

[0049] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling treatment 6 times: the initial speed ratio of asynchronous rolling was 1.6, the initial reduction was 24%, the reduction was reduced by 4% and the speed ratio was reduced by 0.1 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0050] (7) The alloy was subjected to constant temperature vacuum treatment at 20℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 4.

[0051] Table 3

[0052]

[0053] Table 4

[0054] Yield strength / MPa Tensile strength / MPa elongation 392 465 19％

[0055] Example 3

[0056] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0057] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 5, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 40kW, inert gas of argon, and nozzle flow rate of 105L / min.

[0058] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0059] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0060] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0061] (5) Pre-aging treatment: Pre-aging treatment at 100℃ for 30 min.

[0062] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling treatment 4 times: the initial speed ratio of asynchronous rolling was 1.5, the initial reduction was 24%, the reduction was reduced by 6% and the speed ratio was 0.2 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0063] (7) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 6.

[0064] Table 5

[0065]

[0066] Table 6

[0067] Yield strength / MPa Tensile strength / MPa elongation 401 478 20％

[0068] Example 4

[0069] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0070] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 7, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 30kW, inert gas of argon, and nozzle flow rate of 105L / min.

[0071] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0072] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0073] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0074] (5) Pre-aging treatment: Pre-aging treatment at 100℃ for 30 min.

[0075] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling five times: the initial speed ratio of asynchronous rolling was 1.7, the initial reduction was 24%, the reduction was reduced by 4% and the speed ratio was reduced by 0.2 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0076] (7) The alloy was subjected to constant temperature vacuum treatment at 15℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 8.

[0077] Table 7

[0078]

[0079] Table 8

[0080] Yield strength / MPa Tensile strength / MPa elongation 393 495 22％

[0081] Example 5

[0082] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0083] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 9, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were fully mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 30kW, inert gas of argon, and nozzle flow rate of 100L / min.

[0084] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0085] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0086] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0087] (5) Pre-aging treatment: Pre-aging treatment at 90℃ for 30 min.

[0088] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling treatment 4 times: the initial speed ratio of asynchronous rolling was 1.4, the initial reduction was 24%, the reduction was reduced by 5% and the speed ratio was reduced by 0.2 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0089] (7) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 10.

[0090] Table 9

[0091]

[0092] Table 10

[0093] Yield strength / MPa Tensile strength / MPa elongation 410 470 23％

[0094] Comparative Example 1

[0095] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0096] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 1, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 20-40kW, inert gas of argon, and nozzle flow rate of 100-110L / min.

[0097] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0098] (3) The blank is placed in a microwave sintering furnace and heated for sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5~5.5kW, and the atmosphere is argon.

[0099] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0100] (5) Pre-aging treatment: Pre-aging treatment at 90℃ for 30 min.

[0101] (6) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 11.

[0102] Table 11

[0103] Yield strength / MPa Tensile strength / MPa elongation 354 440 17％

[0104] A comparison with Example 1 shows that the "asynchronous rolling + cryogenic treatment" process cyclic processing fully refines the alloy grains, causes grain boundaries to move, and orients towards a strong and tough [1,0,0] texture, thereby regulating the material structure and products, causing the precipitation of the solid hard phase Al3Li, thus increasing the strength and toughness of the aluminum alloy.

[0105] Comparative Example 2

[0106] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0107] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 3, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were fully mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 20-40kW, inert gas of argon, and nozzle flow rate of 100-110L / min.

[0108] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0109] (3) The blank is placed in a microwave sintering furnace and heated for sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5~5.5kW, and the atmosphere is argon.

[0110] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0111] (5) The alloy after solution treatment and quenching cycle treatment was subjected to asynchronous rolling and deep cryogenic cycle treatment 6 times: the initial speed ratio of asynchronous rolling was 1.6, the initial reduction was 24%, the reduction was reduced by 4% and the speed ratio was reduced by 0.1 in each cycle, the deep cryogenic time was 30 min in each cycle, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 12.

[0112] Table 12

[0113] Yield strength / MPa Tensile strength / MPa elongation 378 440 18％

[0114] A comparison with Example 2 shows that pre-aging treatment and isothermal vacuum treatment can significantly improve the strength and toughness of the material. In Example 2, pre-aging treatment can provide heterogeneous nucleation points for subsequent isothermal vacuum treatment, reducing the negative effects of natural aging. Because it is in a vacuum environment without interference from gases and oxides, isothermal vacuum treatment reduces heterogeneity, makes the grain orientation more uniform, and reduces the formation of textures in other directions, so that the alloy obtains a tough [1,0,0] texture, thereby increasing the strength and toughness of the aluminum alloy.

[0115] Comparative Example 3

[0116] The only difference between the preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy described in this comparative example and that in Example 3 is the chemical composition (wt%) of the alloy. The chemical composition of the alloy in this comparative example is shown in Table 13. The tensile strength and elongation of the finally obtained aluminum alloy are shown in Table 14.

[0117] Table 13

[0118]

[0119] Table 14

[0120] Yield strength / MPa Tensile strength / MPa elongation 362 433 17％

[0121] A comparison with Example 3 shows that the aluminum alloy sample without the addition of rare earth elements La, Sc, Pr, and Zr has lower strength and toughness than the sample with La, Sc, Pr, and Zr. This is mainly because the presence of rare earth elements La, Sc, Pr, and Zr significantly refines the grains of the aluminum-magnesium-silicon alloy, forming a dispersed hardened L12 phase Al3 (La, Sc, Pr, Zr). Furthermore, the residual rare earth elements are enriched at the grain boundaries, inhibiting the diffusion of other elements and the movement of grain boundaries, slowing down the growth rate of the α-Al matrix, and thus improving the strength and toughness of the alloy.

[0122] Comparative Example 4

[0123] The only difference between the preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy described in this comparative example and that in Example 3 is the chemical composition (wt%) of the alloy. The chemical composition of the alloy in this comparative example is shown in Table 15. The tensile strength and elongation of the finally obtained aluminum alloy are shown in Table 16.

[0124] Table 15

[0125]

[0126] Table 16

[0127] Yield strength / MPa Tensile strength / MPa elongation 368 496 17％

[0128] A comparison with Example 4 shows that the excessive addition of lithium will cause the alloy grains to grow larger and coarser, tending to result in a textured structure with poor strength and toughness. Although the excessive addition of copper increases strength, its plasticity is greatly reduced, which in turn reduces the strength and toughness of the alloy.

[0129] Comparative Example 5

[0130] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0131] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium copper alloy in Table 1, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium copper alloy raw materials are fully mixed to obtain alloy powder.

[0132] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0133] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0134] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0135] (5) Pre-aging treatment: Pre-aging treatment at 90℃ for 30 min.

[0136] (6) The pre-aged alloy was subjected to asynchronous rolling and deep cryogenic cycling five times: the initial speed ratio of asynchronous rolling was 1.6, the initial reduction was 24%, the reduction was reduced by 5% and the speed ratio was reduced by 0.2 in each cycle, and the deep cryogenic time was 30 min in each cycle.

[0137] (7) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 17.

[0138] Table 17

[0139] Yield strength / MPa Tensile strength / MPa elongation 372 430 19％

[0140] A comparison with Example 1 shows that mixing via plasma inert gas atomization yields alloy powder with high sphericity and low impurity content. On one hand, the high sphericity results in uniform and densely packed powder particles, which improves compressibility and provides favorable conditions for obtaining sintered bodies with smaller grain sizes and uniform structures. On the other hand, the low impurity content reduces the impact of impurities on the sintering process, improves chemical purity, and reduces the formation of undesirable orientations and phases, thereby synergistically improving the strength and toughness of the alloy and obtaining the desired strong and tough texture.

[0141] Comparative Example 6

[0142] A method for preparing a high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy includes the following steps:

[0143] (1) According to the composition (wt%) of the high strength and high toughness textured rare earth aluminum-lithium-copper alloy in Table 1, the rare earth raw materials Sc, Zr, Pr and Tb and the aluminum-lithium-copper alloy raw materials were mixed by plasma inert gas atomization treatment. Then, the two were thoroughly mixed under vacuum and subjected to plasma inert gas atomization treatment again to obtain alloy powder. The parameters of plasma inert gas atomization treatment were: DC plasma gun power of 30kW, inert gas of argon, and nozzle flow rate of 100L / min.

[0144] (2) Press the alloy powder into a rectangular blank by a hydraulic press at a pressure of 200 MPa and a holding time of 10 min.

[0145] (3) The blank is placed in a microwave sintering furnace for heating and sintering. The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5.5kW, and the atmosphere is argon.

[0146] (4) Solution and quenching cycle treatment 3 times: the initial solution temperature is 480℃, the solution temperature increases by 25℃ for each cycle, the solution time for each cycle is 30min, and the quenching media for the three cycles are water, CL-1 organic quenching agent and mineral oil respectively.

[0147] (5) Pre-aging treatment: Pre-aging treatment at 90℃ for 30 min.

[0148] (6) The pre-aged alloy was subjected to asynchronous rolling and cryogenic treatment in sequence: the speed ratio of asynchronous rolling was 1.6, the reduction was 70%, and the cryogenic treatment time was 150 min.

[0149] (7) The alloy was subjected to constant temperature vacuum treatment at 25℃ for 30 min, and then air-cooled in the furnace to obtain a high-strength and high-toughness textured rare earth aluminum-lithium-copper alloy. Its tensile strength and elongation are shown in Table 18.

[0150] Table 18

[0151] Yield strength / MPa Tensile strength / MPa elongation 380 435 18％

[0152] A comparison with Example 1 shows that after pre-aging treatment, asynchronous rolling and deep cryogenic cycling five times can introduce a large number of dislocations and grain boundaries, promote grain refinement and uniform distribution, eliminate residual stress and increase dislocation density. After multiple cycles, an Al3Li hardened phase and a preferred strong and tough [1,0,0] texture can be obtained, which further improves the strength and toughness of the alloy.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high-strength high-ductility textured rare earth aluminum lithium copper alloy, characterized in that, The alloy composition is optimized by adding Sc, Zr, Pr and Tb elements, combined with the plasma inert gas atomization, pressing, sintering, high-temperature solid solution and quenching cycle, aging, asynchronous rolling and deep cooling cycle, constant temperature vacuum treatment process, comprising the following steps: (1) Sc, Zr, Pr and Tb rare earth raw materials, aluminum lithium copper alloy raw materials are respectively subjected to plasma inert gas atomization treatment and mixed, then the two are mixed under vacuum, and then subjected to plasma inert gas atomization treatment again; (2) The powder obtained in step (1) is pressed into a blank; (3) The blank is microwave sintered, then solid solution and quenching cycle treatment 3 times, and finally pre-aging treatment; (4) The alloy after pre-aging treatment is subjected to asynchronous rolling and deep cooling cycle treatment not less than 4 times; (5) The high-strength high-toughness textured rare earth aluminum lithium copper alloy is obtained after constant temperature vacuum treatment; The high-strength high-toughness textured rare earth aluminum lithium copper alloy comprises the following mass percentage components: 0.8~1.1% Li, 3.7~4.2% Cu, 0.7~1.0% Sc, 0.02~0.04% Zr, 0.01~0.03% Pr, 0.01~0.02% Tb, and the balance of Al and unavoidable impurities; The solid solution and quenching cycle treatment 3 times is specifically: the first solid solution temperature is 480℃, the solid solution temperature increases by 25℃ each cycle, the solid solution time is 30min each cycle, and the quenching medium is water, CL-1 organic quenching agent and mineral oil respectively; The asynchronous rolling and deep cooling cycle treatment specifically includes: the initial speed ratio of asynchronous rolling is 1.4~1.7, the initial reduction is 24%, the reduction is reduced by 4~6% and the speed ratio is reduced by 0.1~0.2 each cycle, and the deep cooling time is 20~30min each cycle; The constant temperature vacuum treatment has a temperature of 15-25℃, a time of 30 min, and a vacuum degree of 10 -3 Pa or below.

2. The preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy as described in claim 1, characterized in that, The process parameters of the plasma inert gas atomization treatment are: the direct current plasma gun power is 20~40kW, the inert gas is argon, and the gun mouth flow rate is controlled at 100~110L / min.

3. The preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy as described in claim 1, characterized in that, In step (2), the pressure of pressing is 200MPa, and the pressure holding time is 10min.

4. The preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy as described in claim 1, characterized in that, The microwave sintering temperature is 580℃, the heating rate is 50℃ / min, the sintering time is 10h, the microwave frequency is 2.45GHz±10MHz, the microwave power is 5~5.5kW, and the atmosphere is argon.

5. The preparation method of the high-strength, high-toughness textured rare-earth aluminum-lithium-copper alloy as described in claim 1, characterized in that, The pre-aging treatment temperature is 80-100℃, and the time is 30min.

6. The method of producing high-strength and high-ductility textured rare earth-Al-Li-Cu alloy according to claim 1, wherein The total reduction of asynchronous rolling and deep cooling cycle treatment is 65~74%.

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