A high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy and its preparation method

Abstract

This application belongs to the field of high-strength heat-resistant aluminum alloy preparation technology, specifically relating to a high-strength heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy and its preparation method. The preparation method includes the following steps: S1, obtaining an Al-Cu-Zn-Mg-Sc-Hf alloy billet, homogenizing, hot-rolling, and solution-solventizing the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain a first alloy, wherein the composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet is as follows (by mass percentage): The composition is as follows: Cu: 3.50%-4.50%, Zn: 3.0%-4.0%, Mg: 1.20%-1.50%, Zr: 0.10%-0.20%, Sc: 0.05%-0.15%, Hf: 0.10%-0.30%, with the remainder being Al and unavoidable impurities; S2, the first alloy is subjected to electrical pulse aging to obtain a second alloy; S3, the second alloy is subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy. This application employs a combination of composite microalloying and electrical pulse deformation and re-aging to design a low-interface-energy composite microstructure with multiple precipitated phases, thereby synergistically improving the room-temperature mechanical properties and heat resistance of the alloy.

Description

Technical Field

[0001] This application relates to the field of high-strength heat-resistant aluminum alloy preparation technology, specifically, this application relates to a high-strength heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy and its preparation method. Background Technology

[0002] Al-Cu-Mg (2xxx series) alloys, as typical lightweight materials, have become a major research focus due to their excellent specific strength, superior corrosion resistance, and good weldability. Currently, the development of deep space exploration and the technological innovation of weaponry require Al-Cu-Mg alloys to achieve strengths exceeding 100 MPa under service conditions of 400℃. Aircraft face harsh conditions exceeding 1000℃ during service, and critical components such as aircraft skin and internal load-bearing parts, even under the protection of thermal insulation layers, will exceed 400℃. This leads to severe coarsening of precipitated phases in the alloy, resulting in rapid softening and failure. Therefore, the thermal stability of precipitated phases will become a major challenge in the field of aluminum alloys and light alloys.

[0003] Studies have shown that commercially available 2xxx series aluminum alloys are only suitable for use at 200℃, far below the 400℃ service requirement. Therefore, researchers mainly enhance the thermal stability of Al-Cu-Mg alloys by stabilizing precipitates and constructing low-energy interfaces. Adding trace elements to Al-Cu-Mg alloys promotes solute atom segregation at the interface, improving the thermal stability of the precipitates, achieving a heat resistance temperature up to 350℃. However, when the service temperature exceeds 350℃, the precipitates tend to coarsen.

[0004] Existing technologies still suffer from the problem of unstable precipitates in the alloy, which deteriorates the thermodynamic properties of aluminum alloys, and insufficient strength of traditional heat-treated aluminum alloys during high-temperature service. Therefore, there is an urgent need for a high-strength and heat-resistant Al-Cu-Mg alloy and its preparation method to solve the above problems. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this application provides a method for preparing a high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps: S1, obtaining an Al-Cu-Zn-Mg-Sc-Hf alloy billet, homogenizing, hot-rolling, and solution-solidifying the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain a first alloy, wherein the composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet by mass percentage is: Cu: 3.50%-4.50%, Zn: 3.0%-4.0%, Mg: 1.20%-1.50%, Zr: 0.10%-0.20%, Sc: 0.05%-0.15%, Hf: 0.10%-0.30%, with the remainder being Al and unavoidable impurities; S2, subjecting the first alloy to electrical pulse aging to obtain a second alloy; S3, subjecting the second alloy to electrical pulse deformation and re-aging to obtain the Al-Cu-Zn-Mg-Sc-Hf alloy.

[0006] As a preferred embodiment of the preparation method of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, the specific method for obtaining the Al-Cu-Zn-Mg-Sc-Hf alloy billet in step S1 is as follows: according to the composition ratio of the raw materials of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, the raw materials include pure aluminum ingots, pure magnesium ingots, pure silver ingots, aluminum master alloys and rare earth alloys, the raw materials are smelted and cast in a resistance furnace at 720-760℃ to obtain the Al-Cu-Zn-Mg-Sc-Hf alloy billet.

[0007] As a preferred embodiment of the preparation method of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, in step S1, the homogenization temperature is 470-510℃ and the homogenization time is 28-36h.

[0008] As a preferred embodiment of the preparation method of a high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, in step S2, the temperature of the electrical pulse aging is 150-180℃, the duration of the electrical pulse aging is 7-9 hours, and the cooling method of the electrical pulse aging is water cooling.

[0009] As a preferred embodiment of the preparation method of a high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, in step S3, the pulse voltage of the electrical pulse deformation and re-aging is 10-14V, the pulse width of the electrical pulse deformation and re-aging is 20-25μs, and the frequency of the electrical pulse deformation and re-aging is 300-350Hz.

[0010] As a preferred embodiment of the preparation method of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, in step S3, the temperature of the electrical pulse deformation and re-aging is 350-400℃, the time of the electrical pulse deformation and re-aging is 1-3h, and the cooling method of the electrical pulse deformation and re-aging is water cooling.

[0011] As a preferred embodiment of the preparation method of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, in step S3, the strain of the electrical pulse deformation and re-aging is 10%-20%.

[0012] This application also provides a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, which is prepared by the above-described method for preparing high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy.

[0013] As a preferred embodiment of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, the Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥535MPa at room temperature and an elongation ≥9.0% at room temperature.

[0014] As a preferred embodiment of the high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy described in this application, the Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥95MPa at a high temperature of 400℃ and an elongation ≥16.5% at a high temperature of 400℃.

[0015] The beneficial effects of this application are as follows:

[0016] This application proposes a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy. Composite Sc and Hf microalloying is performed in the Al-Cu-Zn-Mg-Sc-Hf alloy to generate nano-S-Al2CuMg and T-Mg. 32 (Al,Zn) 49Multiple precipitates, including η-MgZn2, V-AlCuSc, and L12-Al3 (Sc, Zr, Hf), were observed. Furthermore, the interaction between composite microalloying and electrical pulse deformation reaging was employed to maximize the creation of low-energy interfaces for the precipitates, synergistically improving the room-temperature mechanical properties and heat resistance of the Al-Cu-Zn-Mg-Sc-Hf alloy. After solution treatment, the samples underwent electrical pulse aging; the non-thermal effect of the pulsed current promoted the aging precipitation process of the Al-Cu-Zn-Mg-Sc-Hf alloy. Electrical pulse deformation introduced dislocation structures, which, combined with trace amounts of Sc and Hf elements, increased the diffusion rate of Sc and Hf elements at high temperatures, promoting atomic segregation towards the precipitate / Al matrix interface. Based on the combined effects of electropulse thermal and non-thermal effects, the activation energy of cluster dissolution can be significantly reduced and atomic diffusion accelerated, which is conducive to the segregation or occupation of solute atoms at the precipitate interface. This results in precipitates with low interfacial energy during re-aging, further creating a multiphase stable microstructure. Furthermore, it overcomes the significant limitations of traditional heat treatment furnaces in terms of high energy consumption, low efficiency, complex equipment structure, and flexibility and applicability, further improving the efficiency and flexibility of the heat treatment process. By implementing an effective and executable electropulse deformation re-aging process and Sc / Hf composite microalloying, the traditional concept that unstable precipitates degrade the thermodynamic properties of aluminum alloys is broken, overcoming the bottleneck problem of insufficient strength in high-temperature service of traditional heat-treated aluminum alloys.

[0017] This application utilizes pulsed electronic effects and dislocation structures to accelerate the diffusion and segregation of solute atoms at the precipitate phase interface, forming a low-interface-energy composite microstructure with multiple precipitate phases. A combined approach of composite microalloying and electrical pulse deformation followed by aging is employed to design this low-interface-energy composite microstructure, synergistically enhancing the room-temperature mechanical and heat-resistant properties of the alloy. First, electrical pulse aging is performed at a low temperature of 150-180℃ for 7-9 hours to promote the co-precipitation of multiple precipitate phases. Then, electrical pulse deformation followed by aging at 350-400℃ for 1-3 hours introduces dislocation structures with varying strain. Under the influence of pulsed current, the electronic effect reduces the chemical potential of vacancies at the precipitate phase interface, providing a driving force for vacancy migration. Solute atoms in the matrix are carried by these vacancies and move along the current direction. Meanwhile, under the combined effect of the thermal and electric field effects of the pulsed current, the solute atoms exhibit higher mobility, promoting the full diffusion of Sc and Hf atoms into the precipitated phase to form a low-energy interface. The purpose of micro-addition of Sc and Hf is to segregate at the precipitated phase / Al matrix interface to form a low interface energy, thereby stabilizing the precipitated phase. The purpose of electric pulse deformation and re-aging is to improve the diffusion rate of Sc and Hf solute atoms under the coupling effect of thermo-electric-mechanical fields, and to enable them to move and segregate along the current direction at the precipitated phase interface, thereby forming a low-energy interface structure with multiple precipitated phases coexisting.

[0018] The advantage of this application lies in the combination of composite microalloying and electro-pulse deformation re-aging process, which breaks the traditional concept that unstable precipitates are detrimental to the heat resistance of aluminum alloys. By controlling the precipitate interface of the alloy, its characteristics for service in room temperature / high temperature environments are met. The low interface energy multiple precipitate coexistence approach utilizes the low diffusion coefficients of Sc and Hf atoms to diffuse and form a low-energy interface heat-resistant phase under the action of a thermo-electric-mechanical composite field, suppressing the coarsening of precipitates and synergistically improving the room temperature performance and heat resistance of the alloy. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 The following are multiple precipitation phase diagrams of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 5 of this application;

[0021] Figure 2 This is a diagram of the dislocation structure of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 5 of this application.

[0022] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0025] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet, homogenize, hot-roll, and solution-solvent the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain a first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet by mass percentage is: Cu: 3.50%-4.50%, Zn: 3.0%-4.0%, Mg: 1.20%-1.50%, Zr: 0.10%-0.20%, Sc: 0.05%-0.15%, Hf: 0.10%-0.30%, with the remainder being Al and unavoidable impurities.

[0026] The specific method for obtaining the Al-Cu-Zn-Mg-Sc-Hf alloy billet is as follows: Based on the composition ratio of the raw materials for the Al-Cu-Zn-Mg-Sc-Hf alloy billet, the raw materials include pure aluminum ingots, pure magnesium ingots, pure silver ingots, aluminum master alloys, and rare earth alloys. The raw materials are melted and cast in a resistance furnace at 720-760℃ to obtain the Al-Cu-Zn-Mg-Sc-Hf alloy billet. The homogenization temperature is 470-510℃, and the homogenization time is 28-36 hours.

[0027] Specifically, the homogenization temperature is any one of 470℃, 480℃, 490℃, 500℃, and 510℃, or a range between any two; the homogenization time is any one of 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, and 36h, or a range between any two.

[0028] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy;

[0029] The temperature of the electrical pulse aging is 150-180℃, the duration of the electrical pulse aging is 7-9 hours, and the cooling method of the electrical pulse aging is water cooling;

[0030] Specifically, the temperature for electrical pulse aging is any one or any two of 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, and 180℃; the duration of electrical pulse aging is any one or any two of 7h, 7.5h, 8h, 8.5h, and 9h.

[0031] S3. The second alloy is subjected to electrical pulse deformation and reaging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy;

[0032] The pulse voltage of the electrical pulse deformation re-aging is 10-14V, the pulse width of the electrical pulse deformation re-aging is 20-25μs, the frequency of the electrical pulse deformation re-aging is 300-350Hz, the temperature of the electrical pulse deformation re-aging is 350-400℃, the time of the electrical pulse deformation re-aging is 1-3h, the cooling method of the electrical pulse deformation re-aging is water cooling, and the strain of the electrical pulse deformation re-aging is 10%-20%.

[0033] Specifically, the pulse voltage for the electrical pulse deformation re-aging is any one or any two of 10V, 11V, 12V, 13V, and 14V; the pulse width for the electrical pulse deformation re-aging is any one or any two of 20μs, 21μs, 22μs, 23μs, 24μs, and 25μs; and the frequency for the electrical pulse deformation re-aging is any one or any two of 300Hz, 305Hz, 310Hz, 315Hz, 320Hz, 325Hz, 330Hz, 335Hz, 340Hz, 345Hz, and 350Hz. The range of the electrical pulse deformation re-aging temperature is any one or any two of 350℃, 355℃, 360℃, 365℃, 370℃, 375℃, 380℃, 385℃, 390℃, 395℃, and 400℃; the range of the electrical pulse deformation re-aging time is any one or any two of 1h, 1.5h, 2h, 2.5h, and 3h; and the range of the electrical pulse deformation re-aging strain is any one or any two of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0034] This application also provides a high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, which is prepared by the above-mentioned method for preparing high-strength and heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy;

[0035] The Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥535MPa at room temperature and an elongation ≥9.0% at room temperature; the Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥95MPa at 400℃ and an elongation ≥16.5% at 400℃.

[0036] The technical solution of this application will be further described below with reference to specific embodiments.

[0037] The specific method for obtaining the Al-Cu-Zn-Mg-Sc-Hf alloy billet in the following embodiments is as follows: According to the composition ratio of the raw materials for the Al-Cu-Zn-Mg-Sc-Hf alloy billet, pure Al, Mg, and Zn ingots, Al-50Cu, Al-4Zr, Al-3Sc, and Al-5Hf intermediate alloys are selected. The raw materials are smelted and cast in a resistance furnace at 740°C to obtain the Al-Cu-Zn-Mg-Sc-Hf alloy billet.

[0038] Example 1

[0039] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0040] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0041] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0042] S3. The second alloy was subjected to electrical pulse deformation and reaging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and reaging was 10V, the pulse width was 20μs, the frequency was 300Hz, the temperature was 350℃, the time was 2h, the strain was 10%, and the cooling method was water cooling.

[0043] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 1 was subjected to mechanical property tests at room temperature and 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 537.6 MPa and the elongation at room temperature was 13.1%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 95.3 MPa and the elongation at 400℃ was 18.2%.

[0044] Example 2

[0045] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0046] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0047] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0048] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 10V, the pulse width was 20μs, the frequency was 300Hz, the temperature was 350℃, the time was 2h, the strain was 15%, and the cooling method was water cooling.

[0049] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 2 was subjected to mechanical property tests at room temperature and 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 561.2 MPa and the elongation at room temperature was 9.1%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 99.3 MPa and the elongation at 400℃ was 16.5%.

[0050] Example 3

[0051] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0052] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0053] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0054] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 10V, the pulse width was 20μs, the frequency was 300Hz, the temperature was 350℃, the time was 2h, the strain was 20%, and the cooling method was water cooling.

[0055] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 3 was subjected to mechanical property tests at room temperature and 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 539.1 MPa and the elongation at room temperature was 12.6%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 96.3 MPa and the elongation at 400℃ was 17.5%.

[0056] Example 4

[0057] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0058] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0059] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0060] S3. The second alloy was subjected to electrical pulse deformation and reaging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and reaging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 10%, and the cooling method was water cooling.

[0061] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 4 was subjected to mechanical property tests at room temperature and 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 559.6 MPa and the elongation at room temperature was 9.2%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 110.3 MPa and the elongation at 400℃ was 16.9%.

[0062] Example 5

[0063] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0064] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0065] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0066] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 15%, and the cooling method was water cooling.

[0067] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 5 was subjected to room temperature and 400℃ high temperature mechanical property tests and structural characterization. The results are shown in [reference needed]. Figure 1 and Figure 2 , Figure 1 The following are multiple precipitation phase diagrams of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 5 of this application; Figure 2The diagram shows the dislocation structure of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 5 of this application. The tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature is 578.1 MPa, and the elongation at room temperature is 10.1%. The tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ is 115.2 MPa, and the elongation at 400℃ is 17.3%.

[0068] Example 6

[0069] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0070] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0071] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0072] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 20%, and the cooling method was water cooling.

[0073] The Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Example 6 was subjected to mechanical property tests at room temperature and 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 542.3 MPa and the elongation at room temperature was 9.6%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 105.9 MPa and the elongation at 400℃ was 17.9%.

[0074] Comparative Example 1

[0075] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0076] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0077] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0078] S3. The second alloy is subjected to electrical pulse reaging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse reaging is 10V, the pulse width is 20μs, the frequency is 300Hz, the temperature is 350℃, the time is 2h, and the cooling method is water cooling.

[0079] The mechanical properties of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Comparative Example 1 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 528.5 MPa and the elongation at room temperature was 8.0%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 88.3 MPa and the elongation at 400℃ was 15.8%.

[0080] Comparative Example 2

[0081] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0082] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0083] S2. Artificial aging of the first alloy yields the second alloy; wherein the artificial aging temperature is 160℃, the time is 14h, and the cooling method is water cooling;

[0084] S3. Artificial deformation and re-aging of the second alloy yields an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the artificial deformation and re-aging temperature is 350℃, the time is 10h, the strain is 15%, and the cooling method is water cooling.

[0085] The mechanical properties of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Comparative Example 2 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 533.1 MPa and the elongation at room temperature was 8.9%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 87.2 MPa and the elongation at 400℃ was 16.3%.

[0086] Comparative Example 3

[0087] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg alloy, comprising the following steps:

[0088] S1. Obtain an Al-Cu-Zn-Mg alloy billet. Homogenize, hot-roll, and solution-solidify the Al-Cu-Zn-Mg alloy billet to obtain the first alloy. By mass percentage, the composition of the Al-Cu-Zn-Mg alloy billet is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32h.

[0089] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0090] S3. The second alloy is subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging is 10V, the pulse width is 20μs, the frequency is 300Hz, the temperature is 350℃, the time is 2h, the strain is 20%, and the cooling method is water cooling.

[0091] The mechanical properties of the Al-Cu-Zn-Mg alloy prepared in Comparative Example 3 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg alloy at room temperature was 522.6 MPa and the elongation at room temperature was 7.8%; the tensile strength of the Al-Cu-Zn-Mg alloy at 400℃ was 91.3 MPa and the elongation at 400℃ was 16.1%.

[0092] Comparative Example 4

[0093] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0094] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet. Homogenize, hot-roll, and solution-solution the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0095] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0096] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 300℃, the time was 2h, the strain was 10%, and the cooling method was water cooling.

[0097] The mechanical properties of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Comparative Example 4 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 525.2 MPa and the elongation at room temperature was 8.7%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 92.5 MPa and the elongation at 400℃ was 15.8%.

[0098] Comparative Example 5

[0099] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc alloy, comprising the following steps:

[0100] S1. Obtain an Al-Cu-Zn-Mg-Sc alloy billet. The Al-Cu-Zn-Mg-Sc alloy billet is homogenized, hot-rolled, and solution-treated to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.1%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0101] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0102] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 15%, and the cooling method was water cooling.

[0103] The mechanical properties of the Al-Cu-Zn-Mg-Sc alloy prepared in Comparative Example 5 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc alloy at room temperature was 518.5 MPa and the elongation at room temperature was 7.2%; the tensile strength of the Al-Cu-Zn-Mg-Sc alloy at 400℃ was 89.3 MPa and the elongation at 400℃ was 14.9%.

[0104] Comparative Example 6

[0105] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Hf alloy, comprising the following steps:

[0106] S1. Obtain an Al-Cu-Zn-Mg-Hf alloy billet. Homogenize, hot-roll, and solution-solidify the Al-Cu-Zn-Mg-Hf alloy billet to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Hf alloy billet, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0107] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0108] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 15%, and the cooling method was water cooling.

[0109] The mechanical properties of the Al-Cu-Zn-Mg-Hf alloy prepared in Comparative Example 6 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Hf alloy at room temperature was 519.2 MPa and the elongation at room temperature was 7.3%; the tensile strength of the Al-Cu-Zn-Mg-Hf alloy at 400℃ was 90.4 MPa and the elongation at 400℃ was 15.3%.

[0110] Comparative Example 7

[0111] This application provides a method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, comprising the following steps:

[0112] S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy ingot. Homogenize, hot-roll, and solution-solidify the Al-Cu-Zn-Mg-Sc-Hf alloy ingot to obtain the first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy ingot, by mass percentage, is: Cu: 4.0%, Zn: 3.5%, Mg: 1.35%, Zr: 0.15%, Sc: 0.2%, Hf: 0.2%, with the remainder being Al and unavoidable impurities. The homogenization temperature is 490℃, and the time is 32 hours.

[0113] S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; wherein the electrical pulse aging temperature is 160℃, the time is 8h, and the cooling method is water cooling.

[0114] S3. The second alloy was subjected to electrical pulse deformation and re-aging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; wherein the pulse voltage of the electrical pulse deformation and re-aging was 14V, the pulse width was 25μs, the frequency was 350Hz, the temperature was 400℃, the time was 2h, the strain was 15%, and the cooling method was water cooling.

[0115] The mechanical properties of the Al-Cu-Zn-Mg-Sc-Hf alloy prepared in Comparative Example 7 were tested at room temperature and at 400℃. The results showed that the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at room temperature was 489.4 MPa and the elongation at room temperature was 6.9%; the tensile strength of the Al-Cu-Zn-Mg-Sc-Hf alloy at 400℃ was 78.2 MPa and the elongation at 400℃ was 13.1%.

[0116] The alloys obtained in the examples and comparative examples were subjected to performance tests. The melting point of the alloys was determined using a differential scanning calorimeter (DSC). The tensile strength and elongation of the alloys were tested according to the method of GB / T228.1-2010. The results are shown in Table 1, which is a comparison table of the alloy properties of Examples 1-6 and Comparative Examples 1-7.

[0117] Table 1

[0118]

[0119] As can be seen from the above embodiments and comparative examples: Embodiment 1, combined with Comparative Example 1, shows that the use of electric pulse deformation re-aging can introduce dislocation structures, providing diffusion channels for Sc and Hf atoms at high temperatures, promoting the segregation of atoms towards the precipitate / Al matrix interface. The formed precipitate can enhance room temperature performance and is less prone to coarsening at 400℃, thus improving thermal stability. Embodiment 2, combined with Comparative Example 2, shows that artificial thermal aging only has a simple thermal effect and limited thermo-mechanical coupling effect. Only under the coupling of thermo-electric-mechanical fields can the diffusion rate of Sc and Hf solute atoms be increased, and they can move and segregate along the current direction at the precipitate interface, promoting the aging precipitation of Al-Cu-Zn-Mg-Sc-Hf alloy, and thus forming a low-energy interface structure with multiple precipitate phases. Embodiment 3, combined with Comparative Example 3, shows that adding Sc and Hf atoms to the alloy is beneficial for the segregation of Sc and Hf atoms towards the precipitate interface during the high-temperature aging process, forming a low-energy interface and preventing the coarsening of the precipitate. Embodiment 4, combined with Comparative Example 4, shows that the temperature of electric pulse deformation re-aging... To fully utilize the non-thermal effect of the electric pulse to promote the aging precipitation process of the Al-Cu-Zn-Mg-Sc-Hf alloy, the temperature must be within the range described in this application. This provides diffusion channels for Sc and Hf atoms, thereby increasing the diffusion rate and segregating them at the precipitate phase interface to form a low-energy interface. If the temperature is too low, the diffusion rate of Sc and Hf atoms will be insufficient, preventing segregation at the precipitate phase interface and thus forming a low-energy interface. Example 5, combined with Comparative Example 5, shows that adding only Sc without Hf results in a single segregated layer at the precipitate phase interface with a high interface energy, which is prone to coarsening under high-temperature conditions. However, the combined addition of Sc and Hf forms a composite segregated layer at the precipitate phase interface, resulting in better thermal stability. Example 5, combined with Comparative Example 6, shows that adding only Hf without Sc results in a single segregated layer at the precipitate phase interface with a high interface energy, which is not effective in hindering the coarsening of the precipitate phase. Example 5, combined with Comparative Example 7, shows that adding too much Sc will form a large number of coarse W(AlCuSc) phases during the homogenization process, severely deteriorating the mechanical properties of the alloy.

[0120] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, characterized in that, Includes the following steps: S1. Obtain an Al-Cu-Zn-Mg-Sc-Hf alloy billet, homogenize, hot-roll, and solution-solvent the Al-Cu-Zn-Mg-Sc-Hf alloy billet to obtain a first alloy. The composition of the Al-Cu-Zn-Mg-Sc-Hf alloy billet by mass percentage is: Cu: 3.50%-4.50%, Zn: 3.0%-4.0%, Mg: 1.20%-1.50%, Zr: 0.10%-0.20%, Sc: 0.05%-0.15%, Hf: 0.10%-0.30%, with the remainder being Al and unavoidable impurities. S2. The first alloy is subjected to electrical pulse aging to obtain the second alloy; In step S2, the temperature of the electrical pulse aging is 150-180℃, the duration of the electrical pulse aging is 7-9 hours, and the cooling method for the electrical pulse aging is water cooling. S3. The second alloy is subjected to electrical pulse deformation and reaging to obtain an Al-Cu-Zn-Mg-Sc-Hf alloy; In step S3, the pulse voltage of the electrical pulse deformation re-aging is 10-14V, the pulse width of the electrical pulse deformation re-aging is 20-25μs, and the frequency of the electrical pulse deformation re-aging is 300-350Hz. In step S3, the temperature of the electrical pulse deformation re-aging is 350-400℃, the time of the electrical pulse deformation re-aging is 1-3h, and the cooling method of the electrical pulse deformation re-aging is water cooling. In step S3, the strain of the electrical pulse deformation re-aging is 10%-20%.

2. The method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy according to claim 1, characterized in that, In step S1, the specific method for obtaining the Al-Cu-Zn-Mg-Sc-Hf alloy billet is as follows: according to the composition ratio of the raw materials of the Al-Cu-Zn-Mg-Sc-Hf alloy billet, the raw materials include pure Al, Mg, and Zn ingots, Al-50Cu, Al-4Zr, Al-3Sc, and Al-5Hf master alloys, the raw materials are smelted and cast in a resistance furnace at 720-760℃ to obtain the Al-Cu-Zn-Mg-Sc-Hf alloy billet.

3. The method for preparing a high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy according to claim 1, characterized in that, In step S1, the homogenization temperature is 470-510℃ and the homogenization time is 28-36h.

4. A high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy, characterized in that, The high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy was prepared using the preparation method described in any one of claims 1-3.

5. A high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy according to claim 4, characterized in that, The Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥535MPa at room temperature and an elongation ≥9.0% at room temperature.

6. A high-strength, heat-resistant Al-Cu-Zn-Mg-Sc-Hf alloy according to claim 4, characterized in that, The Al-Cu-Zn-Mg-Sc-Hf alloy has a tensile strength ≥95MPa at 400℃ and an elongation ≥16.5% at 400℃.

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