Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength and high-heat-resistance aluminum-lithium alloy and preparation method thereof

Abstract

The invention relates to the technical field of new materials, in particular to an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength and high-heat-resistance aluminum lithium alloy and a preparation method thereof. According to the invention, Al-Cu-Li-Mg-Ag-Zn-Mn-Zr is used as an alloy system, a certain amount of Cu, Li, Mg and Ag alloy elements are added to obtain a core-shell structure strengthening phase T1-AgMg phase which is stable at a high temperature, a certain amount of Zn element is added to improve the intrinsic stability of the T1 phase, and a certain amount of Mn and Zr alloy elements are added to obtain strengthening phases of a T phase and an Al3Zr phase. The novel high-strength and high-heat-resistance aluminum-lithium alloy with excellent tensile property at room temperature, 250 DEG C and 300 DEG C is obtained by combining proper preparation processes such as casting, homogenization, thermal deformation, solid solution aging and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, in particular to an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr high-strength high-heat-resistant aluminum-lithium alloy and a preparation method thereof. BACKGROUND

[0002] Aluminum alloy is the main material for aircraft fuselage structure and is widely used in load-bearing structural parts with certain temperature resistance requirements. With the rapid development of the aerospace field, the temperature resistance requirement of materials is getting higher and higher. The instantaneous temperature of key structural components such as the front fuselage main load-bearing framework and the rear cabin bulkhead of the current aircraft has reached nearly 300 DEG C, and titanium alloy with greater weight and higher cost has to be selected. At present, there is an urgent need to develop 300 DEG C deformation heat-resistant aluminum alloy to achieve structural weight reduction and reduce manufacturing and maintenance costs.

[0003] In the Al-Cu-Li system of aluminum-lithium alloy, an important strengthening phase T1 phase (Al2CuLi) is formed during aging process. At room temperature, the T1 phase has better strengthening effect than the main strengthening phase in the traditional 2xxx series deformed aluminum alloy. However, the T1 phase is prone to coarsening and loses the strengthening effect above 250 DEG C. SUMMARY

[0004] Therefore, the present application provides an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr high-strength high-heat-resistant aluminum-lithium alloy and a preparation method thereof. The alloy provided by the present application can have excellent room temperature and high temperature strength.

[0005] The present application provides an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr high-strength high-heat-resistant aluminum-lithium alloy, characterized in that it comprises the following components:

[0006] Cu: 4.0% to 4.5%;

[0007] Li: 0.8% to 1.0%;

[0008] Mg: 0.2% to 0.4%;

[0009] Ag: 0.2% to 0.4%;

[0010] Zn: 0.3% to 0.5%;

[0011] Mn: 0.2% to 0.4%;

[0012] Zr: 0.06% to 0.12%;

[0013] the balance is Al and inevitable impurities;

[0014] wherein,

[0015] The Cu / Li mass ratio is 4.5–5.0;

[0016] The Mg / Ag mass ratio is 1.0–1.2;

[0017] The Mn / Zr mass ratio is 3.0 to 3.3.

[0018] This invention also provides a method for preparing Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength and high-heat-resistant aluminum-lithium alloy, comprising the following steps:

[0019] S1. Ingredients:

[0020] The ingredients are prepared according to the target alloy composition;

[0021] The target alloy comprises the following components by weight percentage:

[0022] Cu: 4.0%–4.5%;

[0023] Li: 0.8%–1.0%;

[0024] Mg: 0.2%–0.4%;

[0025] Ag: 0.2%–0.4%;

[0026] Zn: 0.3%–0.5%;

[0027] Mn: 0.2%–0.4%;

[0028] Zr: 0.06%~0.12%;

[0029] The balance consists of Al and unavoidable impurities;

[0030] in,

[0031] The Cu / Li mass ratio is 4.5–5.0;

[0032] The Mg / Ag mass ratio is 1.0–1.2;

[0033] The Mn / Zr mass ratio is 3.0–3.3;

[0034] S2, casting:

[0035] The raw materials are melted, refined, and then cast to obtain alloy ingots;

[0036] S3. Homogenization treatment:

[0037] The alloy ingot obtained in step S2 is subjected to a first homogenization treatment at 390-410℃, and then heated to 490-510℃ for a second homogenization treatment to obtain a homogenized alloy.

[0038] S4. Thermal deformation:

[0039] The homogenized alloy obtained in step S3 is hot-deformed by forging and rolling to obtain the deformed alloy.

[0040] S5, Solid Solution:

[0041] The deformed alloy obtained in step S4 is subjected to a first-step solution treatment at 490-510℃, and then heated to 510-530℃ for a second-step solution treatment to obtain a solution-treated alloy.

[0042] S6. Timeliness:

[0043] The solid solution alloy obtained in step S5 is subjected to a first aging treatment at 180-200℃, and then cooled to 140-160℃ for a second aging treatment to obtain the alloy.

[0044] Preferably, the raw materials used in the formulation include: metal Al, Al50Cu50 master alloy, metal Li, metal Mg, metal Ag, metal Zn, AlMn10 master alloy and AlZr4 master alloy.

[0045] Preferably, in step S3, the heat preservation time for the first homogenization treatment is 8 to 12 hours, and the heat preservation time for the second homogenization treatment is 24 to 48 hours.

[0046] Preferably, in step S4, the thermal deformation process includes:

[0047] S401: Heating of alloys;

[0048] S402: Hot forging of the alloy to obtain a billet;

[0049] S403: The billet is heated and then hot rolled.

[0050] Preferably, in step S401, the heating temperature is 440–460°C, and the holding time is 1–3 hours.

[0051] Preferably, in step S402, the temperature of the hot forging process is ≥350℃.

[0052] Preferably, in step S403, the heating temperature is 440-460℃ and the holding time is 1-3h; during the hot rolling process, after each rolling pass, the alloy is heated at 440-460℃ and held for 20-40min.

[0053] Preferably, in step S5, the heat preservation time of the first solution treatment is 0.5 to 2 hours, and the heat preservation time of the second solution treatment is 2 to 6 hours.

[0054] Preferably, in step S6, the heat preservation time of the first aging treatment is 0.5 to 2 hours, and the heat preservation time of the second aging treatment is 20 to 40 hours.

[0055] This invention uses an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr alloy system, adding certain amounts of Cu, Li, Mg, and Ag alloying elements to obtain a core-shell structure strengthening phase T1-AgMg phase that is stable at high temperatures. A certain amount of Zn element is added to improve the intrinsic stability of the T1 phase, and certain amounts of Mn and Zr alloying elements are added to obtain strengthening phases such as the T phase and Al3Zr phase. Combined with appropriate casting, homogenization, hot deformation, and solution aging processes, a novel high-strength, high-heat-resistant aluminum-lithium alloy with excellent tensile properties at room temperature, 250℃, and 300℃ is obtained. This invention's alloy, based on the core-shell structure precipitated phase T1 (Al2CuLi) with AgMg atomic layers at the interface for strengthening, is supplemented with the T phase (Al2CuLi). 20 The combined strengthening effect of Cu2Mn3 and Al3Zr phases gives the alloy extremely high strength at both room temperature and high temperature (including yield strength and tensile strength).

[0056] The test results show that the room temperature yield strength of the alloy of the present invention is above 561 MPa and the tensile strength is above 587 MPa; the room temperature yield strength at 250℃ is above 350 MPa and the tensile strength is above 387 MPa; and the room temperature yield strength at 500℃ is above 294 MPa and the tensile strength is above 302 MPa. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in this invention, the accompanying drawings used in this invention will be briefly introduced below. Obviously, the drawings described below are merely embodiments of this invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without any creative effort.

[0058] Figure 1 The image shows the microstructure of the strengthening phase T1 precipitated in the alloy; among which, Figure 1 (a) is the distribution diagram of phase T1. Figure 1 (b) is a morphological diagram of phase T1;

[0059] Figure 2 This is a microstructure diagram showing the atomic distribution at the interface between the precipitated strengthening phase T1 and the matrix in the alloy; among which... Figure 2 (a) is a microstructure diagram of the morphology at the interface. Figure 2 (b) is a microstructure diagram of the Cu atom distribution at the interface. Figure 2(c) is a microstructure diagram showing the distribution of Mg atoms at the interface. Figure 2 (d) is a microstructure diagram of the Ag atom distribution at the interface;

[0060] Figure 3 The image shows the microstructure of the Al3Zr phase, a strengthening phase precipitated in the alloy; among them, Figure 3 (a) is a distribution diagram of the Al3Zr phase. Figure 3 (b) shows the morphology of the Al3Zr phase. Figure 3 (c) is a distribution diagram of Zr atoms in Al3Zr;

[0061] Figure 4 This is a microstructure test image of the submicron-sized precipitated strengthening phase T phase in the alloy. Detailed Implementation

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0063] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0064] The term “and / or” as used herein includes any and all combinations of one or more of the related listed items.

[0065] In this document, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0066] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 390~410℃ means that the units for the left endpoint "390" and the right endpoint "410" are both in℃.

[0067] In a first aspect, the present invention provides an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength, high-heat-resistant aluminum-lithium alloy, comprising the following components by mass percentage:

[0068] Cu: 4.0%–4.5%;

[0069] Li: 0.8%–1.0%;

[0070] Mg: 0.2%–0.4%;

[0071] Ag: 0.2%–0.4%;

[0072] Zn: 0.3%–0.5%;

[0073] Mn: 0.2%–0.4%;

[0074] Zr: 0.06%~0.12%;

[0075] The balance consists of Al and unavoidable impurities;

[0076] in,

[0077] The Cu / Li mass ratio is 4.5–5.0;

[0078] The Mg / Ag mass ratio is 1.0–1.2;

[0079] The Mn / Zr mass ratio is 3.0 to 3.3.

[0080] in:

[0081] The specific Cu (copper) content can be 4.00%, 4.01%, 4.02%, 4.03%, 4.04%, 4.05%, 4.06%, 4.07%, 4.08%, 4.09%, 4.10%, 4.11%, 4.12%, 4.13%, 4.14%, 4.15%, 4.16%, 4.17%, 4.18%, 4.19%, 4.20%, 4.21%, 4.22%, 4.23%, etc. 4.24%, 4.25%, 4.26%, 4.27%, 4.28%, 4.29%, 4.30%, 4.31%, 4.32%, 4.34%, 4.35%, 4.36%, 4.37%, 4.38%, 4.39%, 4.40%, 4.41%, 4.42%, 4.43%, 4.44%, 4.45%, 4.46%, 4.47%, 4.48%, 4.49%, 4.50%.

[0082] The specific Li (lithium) content can be 0.80%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.90%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, or 1.00%.

[0083] The specific Mg (magnesium) content can be 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.40%.

[0084] The specific Ag (silver) content can be 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.40%.

[0085] The specific Zn (zinc) content can be 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.50%.

[0086] The specific Mn (manganese) content can be 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.40%.

[0087] The Zr (zirconium) content can be specifically 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, or 0.12%.

[0088] The balance consists of Al and unavoidable impurities. In the alloy, the Cu / Li mass ratio is 4.5–5.0, specifically 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0. The Mg / Ag mass ratio is 1.0–1.2, specifically 1.0, 1.1, or 1.2. The Mn / Zr mass ratio is 3.0–3.3, specifically 3.0, 3.1, 3.2, or 3.3.

[0089] In one embodiment of the present invention, the alloy composition is as follows: Cu: 4.02%, Li: 0.83%, Mg: 0.22%, Ag: 0.21%, Zn: 0.33%, Mn: 0.23%, Zr: 0.07%, with the balance being Al and unavoidable impurities.

[0090] In another embodiment of the invention, the alloy composition is as follows: Cu: 4.31%, Li: 0.89%, Mg: 0.29%, Ag: 0.27%, Zn: 0.42%, Mn: 0.31%, Zr: 0.10%, with the balance being Al and unavoidable impurities.

[0091] In another embodiment of the invention, the alloy composition is as follows: Cu: 4.48%, Li: 0.98%, Mg: 0.38%, Ag: 0.36%, Zn: 0.49%, Mn: 0.39%, Zr: 0.12%, with the balance being Al and unavoidable impurities.

[0092] Secondly, the present invention also provides a method for preparing Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength and high-heat-resistant aluminum-lithium alloy, comprising the following steps:

[0093] S1. Ingredients:

[0094] The ingredients are prepared according to the target alloy composition;

[0095] The target alloy comprises the following components by weight percentage:

[0096] Cu: 4.0%–4.5%;

[0097] Li: 0.8%–1.0%;

[0098] Mg: 0.2%–0.4%;

[0099] Ag: 0.2%–0.4%;

[0100] Zn: 0.3%–0.5%;

[0101] Mn: 0.2%–0.4%;

[0102] Zr: 0.06%~0.12%;

[0103] The balance consists of Al and unavoidable impurities;

[0104] in,

[0105] The Cu / Li mass ratio is 4.5–5.0;

[0106] The Mg / Ag mass ratio is 1.0–1.2;

[0107] The Mn / Zr mass ratio is 3.0–3.3;

[0108] S2, casting:

[0109] The raw materials are melted, refined, and then cast to obtain alloy ingots;

[0110] S3. Homogenization treatment:

[0111] The alloy ingot obtained in step S2 is subjected to a first homogenization treatment at 390-410℃, and then heated to 490-510℃ for a second homogenization treatment to obtain a homogenized alloy.

[0112] S4. Thermal deformation:

[0113] The homogenized alloy obtained in step S3 is hot-deformed by forging and rolling to obtain the deformed alloy.

[0114] S5, Solid Solution:

[0115] The deformed alloy obtained in step S4 is subjected to a first-step solution treatment at 490-510℃, and then heated to 510-530℃ for a second-step solution treatment to obtain a solution-treated alloy.

[0116] S6. Timeliness:

[0117] The solid solution alloy obtained in step S5 is subjected to a first aging treatment at 180-200℃, and then cooled to 140-160℃ for a second aging treatment to obtain the alloy.

[0118] Regarding step S1 :

[0119] S1. Batching: Batching is carried out according to the target alloy composition.

[0120] In this invention, the target alloy is the Al-Cu-Li-Mg-Ag-Zn-Mn-Zr aluminum-lithium alloy described in the previous technical solution. Its composition is consistent with that described in the previous technical solution, and will not be repeated here.

[0121] In this invention, the raw materials used in the formulation preferably include: metal Al, Al50Cu50 master alloy, metal Li, metal Mg, metal Ag, metal Zn, AlMn10 master alloy and AlZr4 master alloy.

[0122] Regarding step S2 :

[0123] S2. Melting and casting: The raw materials are melted, then refined, and then cast to obtain alloy ingots.

[0124] In this invention, the melting temperature is 800℃. Specifically, metals Al, Al50Cu50 master alloy, Mg, Ag, Zn, AlMn10 master alloy, and AlZr4 master alloy are added to a melting furnace and heated to the melting temperature for complete melting to obtain molten metal 1.

[0125] In this invention, after the above-mentioned smelting, refining is carried out to remove surface slag. The refining temperature is 750°C.

[0126] In this invention, after the above-mentioned refining process, a protective gas is introduced into the melting furnace, and then metallic Li is added to obtain molten metal 2. The protective gas is high-purity argon. After the metallic Li is added, the molten metal is stirred after it has fully dissolved to ensure uniform diffusion.

[0127] In this invention, after the above treatment, the molten metal is transferred to a casting device for casting. The transfer process is carried out under the protection of an inert gas, preferably argon. The casting is preferably semi-continuous casting. After casting, an alloy ingot is obtained.

[0128] Regarding step S3 :

[0129] S3. Homogenization treatment: The alloy ingot obtained in step S2 is subjected to the first homogenization treatment at 390-410℃, and then the temperature is raised to 490-510℃ for the second homogenization treatment to obtain a homogenized alloy.

[0130] In this invention, after step S2, the obtained alloy ingot is placed in a homogenization furnace for a two-step homogenization process:

[0131] The temperature for the first homogenization treatment is 390–410℃, specifically 390℃, 391℃, 392℃, 393℃, 394℃, 395℃, 396℃, 397℃, 398℃, 399℃, 400℃, 401℃, 402℃, 403℃, 404℃, 405℃, 406℃, 407℃, 408℃, 409℃, and 410℃. The preferred holding time for the first homogenization treatment is 8–12 hours, specifically 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, and 12 hours.

[0132] The temperature for the second homogenization treatment is 490–510℃, specifically 490℃, 491℃, 492℃, 493℃, 494℃, 495℃, 496℃, 497℃, 498℃, 499℃, 500℃, 501℃, 502℃, 503℃, 504℃, 505℃, 506℃, 507℃, 508℃, 509℃, and 510℃. The preferred holding time for the second homogenization treatment is 24–48 hours, specifically 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, and 48 hours. After the homogenization treatment described in the first step, the furnace is rapidly heated to the temperature for the second homogenization treatment. After the second homogenization treatment is completed, the furnace is preferably cooled to room temperature.

[0133] Regarding step S4 :

[0134] S4. Hot Deformation: The homogenized alloy obtained in step S3 is hot deformed by forging and rolling to obtain the deformed alloy.

[0135] In this invention, after obtaining the homogenized alloy in step S3, it is preferable to saw off the head and tail to ensure that there are no defects at both ends, and at the same time, the alloy surface is peeled before starting the subsequent process.

[0136] In this invention, the heat deformation process in step S4 preferably includes:

[0137] S401: Heating of alloys;

[0138] S402: Hot forging of the alloy to obtain a billet;

[0139] S403: The billet is heated and then hot rolled.

[0140] In step S401: the heating temperature is preferably 440–460°C, specifically 440°C, 445°C, 450°C, 455°C, or 460°C, more preferably 450°C. The heating holding time is preferably 1–3 hours, specifically 1 hour, 2 hours, or 3 hours, more preferably 2 hours. The heating can be carried out in an annealing furnace.

[0141] In step S402: the temperature of the hot forging process is ≥350℃, the intermediate annealing temperature is 440~460℃, and the holding time is 20~40min, more preferably 30min. After hot forging, the alloy is formed into a billet, specifically a square billet.

[0142] In step S403: the heating temperature is preferably 440–460℃, specifically 440℃, 445℃, 450℃, 455℃, 460℃, more preferably 450℃. The holding time for heating is preferably 1–3 hours, specifically 1 hour, 2 hours, 3 hours, more preferably 2 hours. The heating can be carried out in an annealing furnace, that is, after the hot forging in step S402, the billet is placed in an annealing furnace for heating treatment. After the above heating, hot rolling is performed. After each rolling pass, the alloy is heated to ensure its rolling temperature; the heating temperature is preferably 440–460℃, specifically 440℃, 445℃, 450℃, 455℃, 460℃, more preferably 450℃; the holding time for heating is preferably 20–40 minutes, more preferably 30 minutes. Specifically, after each pressing pass, the alloy is placed back into the annealing furnace for holding.

[0143] Regarding step S5 :

[0144] S5. Solution treatment: The deformed alloy obtained in step S4 is subjected to a first-step solution treatment at 490-510℃, and then the temperature is raised to 510-530℃ for a second-step solution treatment to obtain a solution-treated alloy.

[0145] In this invention, after step S4, the obtained alloy is placed in a quenching furnace for solution quenching treatment, specifically a two-step solution treatment:

[0146] The temperature for the first step of solution treatment is 490–510℃, specifically 490℃, 491℃, 492℃, 493℃, 494℃, 495℃, 496℃, 497℃, 498℃, 499℃, 500℃, 501℃, 502℃, 503℃, 504℃, 505℃, 506℃, 507℃, 508℃, 509℃, and 510℃. The preferred holding time for the first step of solution treatment is 0.5–2 hours, specifically 0.5 hours, 1 hour, 1.5 hours, and 2 hours.

[0147] The temperature for the second solution treatment is 510–530℃, specifically 510℃, 511℃, 512℃, 513℃, 514℃, 515℃, 516℃, 517℃, 518℃, 519℃, 520℃, 521℃, 522℃, 523℃, 524℃, 525℃, 526℃, 527℃, 528℃, 529℃, and 530℃. The holding time for the second solution treatment is preferably 2–6 hours, specifically 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, and 6 hours. After the first solution treatment, the furnace is slowly heated to the temperature for the second solution treatment. After the second solution treatment is completed, water quenching to room temperature is preferred.

[0148] Regarding step S6 :

[0149] S6. Aging: The solid solution alloy obtained in step S5 is subjected to the first aging treatment at 180-200℃, and then cooled to 140-160℃ for the second aging treatment to obtain the alloy product.

[0150] In this invention, after obtaining the solid solution alloy through the solution treatment in step S5, the alloy is placed in an aging furnace for aging treatment, specifically involving two aging steps:

[0151] The temperature for the first aging treatment is 180–200℃, specifically 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 186℃, 187℃, 188℃, 189℃, 190℃, 191℃, 192℃, 193℃, 194℃, 195℃, 196℃, 197℃, 198℃, 199℃, and 200℃. The preferred holding time for the first aging treatment is 0.5–2 hours, specifically 0.5 hours, 1 hour, 1.5 hours, and 2 hours.

[0152] The temperature for the second aging treatment is 140–160℃, specifically 140℃, 141℃, 142℃, 143℃, 144℃, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, and 160℃. The preferred holding time for the second aging treatment is 20–40 hours, specifically 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, and 40 hours. After the first aging treatment, the furnace is directly cooled to the temperature for the second aging treatment. After the second aging treatment is completed, the alloy ingot is preferably removed and air-cooled to room temperature.

[0153] This invention uses an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr alloy system, adding certain amounts of Cu, Li, Mg, and Ag alloying elements to obtain a core-shell structure strengthening phase T1-AgMg phase that is stable at high temperatures. A certain amount of Zn element is added to improve the intrinsic stability of the T1 phase, and certain amounts of Mn and Zr alloying elements are added to obtain strengthening phases such as the T phase and Al3Zr phase. Combined with appropriate casting, homogenization, hot deformation, and solution aging processes, a novel high-strength, high-heat-resistant aluminum-lithium alloy with excellent tensile properties at room temperature, 250℃, and 300℃ is obtained. This invention's alloy, based on the core-shell structure precipitated phase T1 (Al2CuLi) with AgMg atomic layers at the interface for strengthening, is supplemented with the T phase (Al2CuLi). 20 The combined strengthening effect of Cu2Mn3 and Al3Zr phases gives the alloy extremely high strength at both room temperature and high temperature (including yield strength and tensile strength).

[0154] The test results show that the room temperature yield strength of the alloy of the present invention is above 561 MPa and the tensile strength is above 587 MPa; the room temperature yield strength at 250℃ is above 350 MPa and the tensile strength is above 387 MPa; and the room temperature yield strength at 500℃ is above 294 MPa and the tensile strength is above 302 MPa.

[0155] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0156] Examples 1-3

[0157] S1. Batching: Batching is carried out according to the target alloy composition.

[0158] S2, casting:

[0159] Weighed Al, Al50Cu50 master alloy, Mg, Ag, Zn, AlMn10 master alloy, and AlZr4 master alloy were placed in a graphite crucible in a melting furnace and heated to 800°C until fully melted, yielding molten metal 1. Molten metal 1 was then refined at 750°C to remove surface slag. After refining, high-purity argon gas was introduced into the melting furnace, followed by the addition of Li. Once fully dissolved, molten metal 1 was stirred to ensure uniform diffusion, yielding molten metal 2. Molten metal 2 was then transferred to a semi-continuous casting device under argon protection for semi-continuous casting, resulting in an alloy ingot with dimensions of Φ180mm × 320mm.

[0160] Three Al-Cu-Li-Mg-Ag-Zn-Mn-Zr alloys with different compositions were prepared using the above method. The resulting ingots were subjected to ICP testing to obtain their actual compositions, as shown in Table 1.

[0161] Table 1: Alloy composition of Examples 1-3

[0162]

[0163] S3. Homogenization treatment:

[0164] The alloy ingot obtained in step S2 is placed in a homogenization furnace for a two-step homogenization process: the first homogenization process is carried out at 400°C and held for 10 hours; the second homogenization process is carried out in the furnace at 500°C and held for 36 hours, and then cooled to room temperature in the furnace.

[0165] S4. Thermal deformation:

[0166] Cut off 20mm from the head and tail of the homogenized alloy ingot obtained in step S3 to ensure that there are no defects at both ends, and at the same time, peel off the surface of the alloy.

[0167] S401: Place the treated alloy in an annealing furnace and heat it to 450°C and hold it for 2 hours.

[0168] S402: The alloy is hot forged, maintaining a temperature not lower than 350℃ during the hot forging process. After three forging and three drawing operations, the alloy is formed into a 30mm thick square billet. The intermediate annealing temperature is 450℃, and the holding time is 30min.

[0169] S403: The billet is placed in an annealing furnace and heated to 450°C and held for 2 hours. Then it is pressed, with a reduction of 2 mm per pass, and the final alloy is rolled to a thickness of 10 mm. After each rolling pass, the alloy is placed back in the annealing furnace and held at 450°C for 30 minutes.

[0170] S5, Solid Solution:

[0171] The rolled plate obtained in step S4 is placed in a quenching furnace for solution treatment: first, it is held at 500℃ for 1 hour, then the temperature is raised to 520℃ and held for 4 hours. Then, it is water-quenched to room temperature.

[0172] S6. Timeliness:

[0173] The solid solution alloy obtained in step S5 was placed in an aging furnace for a two-step aging treatment: first, it was held at 190°C for 1 hour, and then the temperature was lowered to 150°C and held for 30 hours. After that, the alloy ingot was removed and air-cooled to room temperature.

[0174] Comparative Examples 1-3

[0175] Three heat-resistant aluminum alloys, 2618, 2024, and 2040, were prepared according to the production method of Example 1.

[0176] Product testing :

[0177] (1) Characterization:

[0178] Figure 1 The image shows the microstructure of the strengthening phase T1 precipitated in the alloy; among which, Figure 1 (a) is the distribution diagram of phase T1. Figure 1 (b) shows the morphology of the T1 phase. It can be seen that a large number of nanoscale T1 phases are uniformly dispersed in the alloy of the present invention, which are the main reinforcing phases of the alloy.

[0179] Figure 2 This is a microstructure diagram showing the atomic distribution at the interface between the precipitated strengthening phase T1 and the matrix in the alloy; among which... Figure 2 (a) is a microstructure diagram of the morphology at the interface. Figure 2 (b) is a microstructure diagram of the Cu atom distribution at the interface. Figure 2 (c) is a microstructure diagram showing the distribution of Mg atoms at the interface. Figure 2 (d) is a microstructure diagram showing the distribution of Ag atoms at the interface. It can be seen that in the alloy of the present invention, a layer of AgMg atoms is clearly distributed at the interface between the main strengthening phase T1 and the Al matrix.

[0180] Figure 3 The image shows the microstructure of the Al3Zr phase, a strengthening phase precipitated in the alloy; among them, Figure 3 (a) is a distribution diagram of the Al3Zr phase. Figure 3 (b) shows the morphology of the Al3Zr phase. Figure 3 (c) is a distribution diagram of Zr atoms in Al3Zr. It can be seen that a certain amount of Al3Zr phase exists in the alloy of the present invention, and its size is on the nanometer scale, which plays an auxiliary strengthening role.

[0181] Figure 4 This is a microstructure test image of the submicron-sized precipitated strengthening phase T phase in the alloy. It can be seen that a large number of T phases exist in the alloy of this invention, with a size on the submicron scale, and they have a certain strengthening effect.

[0182] (2) Mechanical property testing:

[0183] The alloys of each embodiment and comparative example were subjected to room temperature tensile tests, 250°C tensile tests, and 300°C tensile tests, and the properties were obtained as shown in Table 2.

[0184] Table 2: Performance comparison of the alloy of the present invention with alloys 2618, 2024 and 2040

[0185]

[0186] As can be seen from the test results in the table above, the tensile properties of the alloy of the present invention at room temperature, 250℃ and 300℃ are all higher than those of the three heat-resistant aluminum alloys mentioned above.

[0187] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A high-strength, high-heat-resistant aluminum-lithium alloy based on the Al-Cu-Li-Mg-Ag-Zn-Mn-Zr system, characterized in that, By weight percentage, it includes the following components: Cu: 4.0%–4.5%; Li: 0.8%–1.0%; Mg: 0.2%–0.4%; Ag: 0.2%–0.4%; Zn: 0.3%–0.5%; Mn: 0.2%–0.4%; Zr：0.06％～0.12％； The balance consists of Al and unavoidable impurities; in, The Cu / Li mass ratio is 4.5–5.0; The Mg / Ag mass ratio is 1.0–1.2; The Mn / Zr mass ratio is 3.0 to 3.

3.

2. A method for preparing an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr series high-strength, high-heat-resistant aluminum-lithium alloy, characterized in that, Includes the following steps: S1. Ingredients: The ingredients are prepared according to the target alloy composition; The target alloy comprises the following components by weight percentage: Cu: 4.0%–4.5%; Li: 0.8%–1.0%; Mg: 0.2%–0.4%; Ag: 0.2%–0.4%; Zn: 0.3%–0.5%; Mn: 0.2%–0.4%; Zr：0.06％～0.12％； The balance consists of Al and unavoidable impurities; in, The Cu / Li mass ratio is 4.5–5.0; The Mg / Ag mass ratio is 1.0–1.2; The Mn / Zr mass ratio is 3.0–3.3; S2, casting: The raw materials are melted, refined, and then cast to obtain alloy ingots; S3. Homogenization treatment: The alloy ingot obtained in step S2 is subjected to a first homogenization treatment at 390-410℃, and then heated to 490-510℃ for a second homogenization treatment to obtain a homogenized alloy. S4. Thermal deformation: The homogenized alloy obtained in step S3 is hot-deformed by forging and rolling to obtain the deformed alloy. S5, Solid Solution: The deformed alloy obtained in step S4 is subjected to a first-step solution treatment at 490-510℃, and then heated to 510-530℃ for a second-step solution treatment to obtain a solution-treated alloy. S6. Timeliness: The solid solution alloy obtained in step S5 is subjected to a first aging treatment at 180-200℃, and then cooled to 140-160℃ for a second aging treatment to obtain the alloy.

3. The preparation method according to claim 2, characterized in that, The raw materials used in the formulation include: metal Al, Al50Cu50 master alloy, metal Li, metal Mg, metal Ag, metal Zn, AlMn10 master alloy and AlZr4 master alloy.

4. The preparation method according to claim 2, characterized in that, In step S3, the heat preservation time for the first homogenization treatment is 8 to 12 hours, and the heat preservation time for the second homogenization treatment is 24 to 48 hours.

5. The preparation method according to claim 2, characterized in that, In step S4, the thermal deformation process includes: S401: Heating of alloys; S402: Hot forging of the alloy to obtain a billet; S403: The billet is heated and then hot rolled.

6. The preparation method according to claim 5, characterized in that, In step S401, the heating temperature is 440-460℃, and the holding time is 1-3 hours.

7. The preparation method according to claim 5, characterized in that, In step S402, the temperature of the hot forging process is ≥350℃.

8. The preparation method according to claim 5, characterized in that, In step S403, the heating temperature is 440-460℃ and the holding time is 1-3h; during the hot rolling process, after each rolling pass, the alloy is heated at 440-460℃ and held for 20-40min.

9. The preparation method according to claim 2, characterized in that, In step S5, the heat preservation time for the first solution treatment is 0.5 to 2 hours, and the heat preservation time for the second solution treatment is 2 to 6 hours.

10. The preparation method according to claim 2, characterized in that, In step S6, the heat preservation time of the first aging treatment is 0.5 to 2 hours, and the heat preservation time of the second aging treatment is 20 to 40 hours.

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