A high-strength heat-resistant aluminum-copper-magnesium alloy and its preparation method

Abstract

The present invention relates to the technical field of high-strength, heat-resistant, lightweight structural casting metal materials, and in particular to a high-strength, heat-resistant aluminum-copper-magnesium alloy and a preparation method thereof, which are intended to address the problems of existing high-strength, heat-resistant aluminum-copper-magnesium alloys, such as high cost and low alloy strength at room temperature and at a high temperature of 300°C. The high-strength, heat-resistant aluminum-copper-magnesium alloy comprises the following alloy components, calculated by mass percentage: Cu: 4.5-5.5%, Mg: 1.5-2.5%, Mn: 0.2-1.0%, Ti: 0.1-0.5%, Zr: 0.1-0.5%, Sc: 0.1-0.5%, Fe: 0-0.1%, with the balance being aluminum and unavoidable impurities. The aluminum-copper-magnesium alloy prepared by the present invention is low-cost and exhibits good mechanical properties both at room temperature and at a high temperature of 300°C.

Description

Technical Field

[0001] The present invention relates to the technical field of high-strength, heat-resistant, lightweight structural casting metal materials, and in particular to a high-strength, heat-resistant aluminum-copper-magnesium alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is a lightweight, high-strength alloy widely used in aerospace, automobile manufacturing, shipbuilding and other fields. Due to the short-term high-temperature friction environment during aerospace service, the equipment materials have high heat resistance requirements. Existing alloy grades such as 201.0 alloy have high room temperature and high temperature strength. They mainly add Cu elements to form the θ-Al2Cu strengthening phase, and promote the formation of the Al2Cu high-temperature stable phase Ω through the introduction of Ag elements. However, the Ag element has a high addition cost, and when the service temperature exceeds 250°C, the high-temperature stable phase Ω is replaced by the θ phase, and its strength is difficult to meet the higher requirements of the heat resistance of existing aviation and spacecraft structural materials. Therefore, it is urgent to find a casting aluminum alloy material with more cost advantages and high strength and heat resistance. Summary of the Invention

[0003] In view of the above analysis, the embodiments of the present invention are intended to provide a high-strength and heat-resistant aluminum-copper-magnesium alloy and a preparation method thereof, which are used to at least solve one of the following problems existing in existing high-strength and heat-resistant aluminum-copper-magnesium alloys and preparation methods thereof: 1. Existing high-strength and heat-resistant aluminum-copper-magnesium alloys and preparation methods thereof have high alloy costs; 2. Existing high-strength and heat-resistant aluminum-copper-magnesium alloys have low alloy strength at room temperature and high temperature of 300°C.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] The present invention provides a high-strength and heat-resistant aluminum-copper-magnesium alloy. The alloy components, calculated by mass percentage, are: Cu: 4.5-5.5%, Mg: 1.5-2.5%, Mn: 0.2-1.0%, Ti: 0.1-0.5%, Zr: 0.1-0.5%, Sc: 0.1-0.5%; Fe: 0-0.1%; the balance is aluminum and unavoidable impurities.

[0006] Furthermore, the alloy components are calculated by mass percentage as follows: Cu: 4.94-5.12%, Mg: 1.84-2.32%, Mn: 0.41-0.79%, Ti: 0.1-0.25%, Zr: 0.15-0.22%, Sc: 0.3-0.33%; Fe: 0-0.08%; the balance is aluminum and unavoidable impurities.

[0007] Furthermore, in the alloy component, the mass ratio of Cu / Mg is 2 to 4.

[0008] The present invention also provides a method for preparing a high-strength and heat-resistant aluminum-copper-magnesium alloy, which is used to prepare the above-mentioned aluminum-copper-magnesium alloy, comprising the following steps:

[0009] S1: According to the mass percentage of each element, pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy are weighed as raw materials respectively;

[0010] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first smelting temperature. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continued to be smelted at the first smelting temperature. Keeping the temperature, after the temperature drops to the second smelting temperature, pure magnesium blocks are pressed in with a pressing spoon;

[0011] S3: After all alloying elements are added, refining and degassing are carried out, standing, and slag removal is carried out;

[0012] S4: casting;

[0013] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0014] Furthermore, in step S2, the first smelting temperature is 750-800°C, and the holding time is 30-60 minutes.

[0015] Furthermore, in step S2, the second smelting temperature is 700-730°C.

[0016] Furthermore, in step S3, the step of standing is 20-30 minutes.

[0017] Furthermore, in step S4, the casting process is gravity or low-pressure casting, the pouring temperature is 670-690°C, and the mold insulation temperature is 150-200°C.

[0018] Furthermore, in step S5, the solution treatment is a secondary solution treatment, which is carried out at 490-510°C for 2h-5h, and then at 510-540°C for 5h-10h.

[0019] Furthermore, in step S5, the aging treatment temperature is 150-180° C., and the holding time is 3 h-8 h.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] 1. Compared with existing aluminum-magnesium-copper alloys, the aluminum-copper-magnesium alloy of the present invention introduces a higher concentration of Mg element. The industry average cost of raw magnesium smelting is about 19,000 yuan / ton, which can significantly reduce the alloy addition cost. At the same time, the relative density of Mg element is only 1.74g / cm3, which has a significant lightweight advantage.

[0022] 2. The aluminum-copper-magnesium alloy of the present invention reduces the cost of the prepared aluminum-copper-magnesium alloy through reasonable alloy composition design and precise control of preparation process parameters, and has good mechanical properties at both room temperature and high temperature of 300°C. The present invention significantly promotes the formation of the Al2Cu(Ω) high-temperature stable phase by increasing the Mg element concentration so that the Cu / Mg mass ratio is between 2 and 4, ensuring that the alloy still has high strength at a high temperature of 300°C; introduces Mn and Zr elements to reduce the diffusion rate of Cu element in the matrix Al, delays the dissolution process of the aluminum-copper supersaturated solid solution at high temperature, and ensures that the alloy has higher mechanical properties at high temperature; adds refinement elements such as Ti and Sc to exert fine grain strengthening. At the same time, the rare earth Sc element is enriched at the grain boundaries to form refractory and stable intermetallic compounds with Al, Cu, Mn, etc., which are distributed along the grains and dendrites to form a hard skeleton, effectively hindering grain boundary sliding and creep deformation at room temperature and high temperature, further improving the room temperature and high temperature mechanical properties of the alloy. The present invention fully dissolves the cast Al2Cu precipitated phase into the matrix through a two-stage solid solution process; and controls the dispersion precipitation of the Al2Cu(Ω) high-temperature stable phase through an aging heat treatment process, thereby further improving the room temperature and high-temperature mechanical properties of the alloy.

[0023] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0025] Figure 1 This is a cast microstructure diagram of the high-strength and heat-resistant aluminum-copper-magnesium alloy prepared in Example 1 of the present invention;

[0026] Figure 2 This is the heat-treated microstructure diagram of the high-strength and heat-resistant aluminum-copper-magnesium alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0028] The present invention provides a high-strength and heat-resistant aluminum-copper-magnesium alloy, the components of which are as follows by mass percentage: Cu: 4.5-5.5%, Mg: 1.5-2.5%, Mn: 0.2-1.0%, Ti: 0.1-0.5%, Zr: 0.1-0.5%, Sc: 0.1-0.5%; Fe: 0-0.1%; the balance is aluminum and unavoidable impurities.

[0029] Among them, the mass ratio of Cu / Mg is 2 to 4, which can improve the room temperature and high temperature mechanical properties of the alloy; for example, the mass ratio of Cu / Mg is 2.20, 2.40, 2.60, 2.70, 2.80, 2.90, 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.80, and 3.90.

[0030] The reasons for limiting the composition of the ingot of the high-strength, heat-resistant aluminum-copper-magnesium alloy and the method for producing the same in the present invention are explained below. The mass percentages in the composition are expressed only in %.

[0031] Cu: forms Al2Cu(θ) strengthening phase, improves room temperature and high temperature strength. If the Cu content is too high, the casting is prone to hot cracking defects. In the present invention, the Cu content is 4.5-5.5%;

[0032] Mg: promotes the formation of Al2Cu(Ω) high temperature stable phase and increases high temperature strength. Excessive Mg addition will reduce the casting fluidity of the alloy and also introduce oxide inclusions. In the present invention, the Mg content is 1.5-2.5%;

[0033] Mn: reduces the diffusion rate of Cu in the matrix Al, delays the dissolution process of the supersaturated solid solution of aluminum and copper at high temperatures, and ensures that the alloy has higher mechanical properties at high temperatures; in the present invention, the content of Mn is 0.2-1.0%;

[0034] Ti: refines grains, reduces dendrite arm spacing, and exerts a fine grain strengthening effect; in the present invention, the content of Ti is 0.1-0.5%;

[0035] Zr: Together with Mn, it is used to reduce the diffusion rate of Cu in the matrix Al, delay the dissolution process of the supersaturated solid solution of aluminum and copper at high temperature, and ensure that the alloy has higher mechanical properties at high temperature; in the present invention, the content of Zr is 0.1-0.5%;

[0036] Sc: plays a role in grain refinement and strengthening. At the same time, the rare earth element Sc is enriched at the grain boundaries and forms refractory and stable intermetallic compounds with Al, Cu, Mn, etc., which are distributed along the grains and dendrites to form a hard skeleton. It effectively hinders grain boundary sliding and creep deformation at room temperature and high temperature, further improving the room temperature and high temperature mechanical properties of the alloy. In the present invention, the Sc content is 0.1-0.5%;

[0037] Fe: facilitates alloy demoulding. A content greater than 0.1% will significantly reduce the mechanical properties of the alloy and requires strict control. In the present invention, the Fe content is 0 to 0.1%.

[0038] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.5-5.40%, Mg: 1.5-2.40%, Mn: 0.2-0.90%, Ti: 0.1-0.40%, Zr: 0.1-0.40%, Sc: 0.1-0.40%; Fe: 0-0.09%; the balance is aluminum and unavoidable impurities.

[0039] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.55-5.35%, Mg: 1.55-2.35%, Mn: 0.25-0.85%, Ti: 0.15-0.35%, Zr: 0.15-0.35%, Sc: 0.15-0.35%; Fe: 0.005-0.085%; the balance is aluminum and unavoidable impurities.

[0040] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.6-5.30%, Mg: 1.6-2.30%, Mn: 0.3-0.80%, Ti: 0.18-0.30%, Zr: 0.18-0.30%, Sc: 0.18-0.30%; Fe: 0.01-0.08%; the remainder is aluminum and unavoidable impurities.

[0041] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.66-5.25%, Mg: 1.66-2.25%, Mn: 0.34-0.75%, Ti: 0.21-0.28%, Zr: 0.19-0.25%, Sc: 0.19-0.25%; Fe: 0.015-0.075%; the balance is aluminum and unavoidable impurities.

[0042] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.70-5.20%, Mg: 1.70-2.20%, Mn: 0.42-0.70%, Ti: 0.23-0.26%, Zr: 0.20-0.23%, Sc: 0.20-0.24%; Fe: 0.02-0.06%; the balance is aluminum and unavoidable impurities.

[0043] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.73-5.15%, Mg: 1.75-2.15%, Mn: 0.53-0.65%, Ti: 0.19-0.25%, Zr: 0.19-0.22%, Sc: 0.21-0.23%; Fe: 0.025-0.055%; the balance is aluminum and unavoidable impurities.

[0044] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.86-5.10%, Mg: 1.83-2.10%, Mn: 0.2-0.60%, Ti: 0.1-0.16%, Zr: 0.1-0.16%, Sc: 0.1-0.16%; Fe: 0.03-0.05%; the remainder is aluminum and unavoidable impurities.

[0045] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.5-5.05%, Mg: 1.5-2.05%, Mn: 0.2-0.55%, Ti: 0.1-0.15%, Zr: 0.1-0.15%, Sc: 0.1-0.15%; Fe: 0.035-0.045%; the balance is aluminum and unavoidable impurities.

[0046] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.6-5.00%, Mg: 1.6-2.0%, Mn: 0.2-0.50%, Ti: 0.1-0.13%, Zr: 0.1-0.13%, Sc: 0.1-0.13%; Fe: 0.037-0.04%; the balance is aluminum and unavoidable impurities.

[0047] Preferably, a high-strength and heat-resistant aluminum-copper-magnesium alloy, whose components, in terms of mass percentage, are: Cu: 4.94-5.12%, Mg: 1.84-2.32%, Mn: 0.41-0.79%, Ti: 0.1-0.25%, Zr: 0.15-0.22%, Sc: 0.3-0.33%; Fe: 0.043-0.08%; the remainder is aluminum and unavoidable impurities.

[0048] Preferably, the mass ratio of Cu / Mg is 2.20 to 2.68, such as 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, 2.28, 2.29, 2.30, 2.31, 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40, 2.41, 2.42, 2.43, 2.44, 2.45, 2.46, 2.47, 2.48, 2.49, 2.50, 2.51, 2.52, 2.53, 2.54, 2.55, 2.56, 2.57, 2.58, 2.59, 2.60, 2.61, 2.62, 2.63, 2.64, 2.65, 2.66, 2.67.

[0049] The present invention also provides a preparation method of the above-mentioned high-strength and heat-resistant aluminum-copper-magnesium alloy, comprising separately adding a pure Mg block during the preparation process, degassing, standing and heat treatment during the refining process; the melting temperature when the pure Mg block is added is lower than the melting temperature of the remaining raw materials, generally 700-730°C; the standing time during the refining process is 20-30 minutes; the heat treatment is a secondary solid solution treatment and an aging treatment, the solid solution treatment is kept at 490-510°C for 2h-5h, then kept at 510-540°C for 5h-10h, and then quenched and then aged at 150-180°C for 3h-8h.

[0050] The present invention also provides a method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy, comprising the following steps:

[0051] S1: According to the mass percentage of each element, pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy are weighed as raw materials respectively;

[0052] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first smelting temperature. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continued to be smelted at the first smelting temperature. Keeping the temperature, after the temperature drops to the second smelting temperature, pure magnesium blocks are pressed in with a pressing spoon;

[0053] S3: After all alloying elements are added, refining and degassing are carried out, standing, and slag removal is carried out;

[0054] S4: casting;

[0055] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0056] Specifically, in step S1, pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy are weighed as raw materials according to the mass percentage of each element.

[0057] Specifically, in step S2, smelting begins, and pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys are added to the resistance furnace, and the alloys are kept at a first smelting temperature of 750-800°C for 30-60 minutes. Smelting at this temperature is conducive to the full dissolution of the master alloy elements and improves the smelting efficiency. After the pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys are cleared, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 750-800°C. After they are completely melted, they are kept warm for 30-60 minutes. Then, after the temperature drops to a second smelting temperature of 700-730°C, a pure magnesium block is pressed in with a pressing spoon. The lower smelting temperature is conducive to reducing the burn-off of the Mg element.

[0058] Specifically, in step S3, after all alloy elements are added, refining and degassing are carried out, and the mixture is allowed to stand for 20-30 minutes, and slag is removed. The gas used for refining and degassing is preferably an inert gas such as nitrogen or argon, and rotary spraying and degassing are performed throughout the process.

[0059] Specifically, the casting process is gravity or low-pressure casting, the pouring temperature is 670-690°C, and the mold insulation temperature is 150-200°C. The lower pouring temperature can reduce the burnout of magnesium elements, increase the solidification undercooling, thereby increasing the driving force of tissue nucleation and refining the grain size; mold insulation within a certain range can ensure complete filling of the casting and improve the surface quality of the casting. Too low mold temperature will lead to difficulties in product molding, weld lines and defects such as uneven product surface; too high mold temperature will easily lead to defects such as surface bubbles, mold sticking, shrinkage holes, and the mold is prone to deformation.

[0060] Specifically, in step S5, the solution treatment is a secondary solution treatment, which is kept at 490-510°C for 2h-5h, then kept at 510-540°C for 5h-10h, and then quenched and aged at 150-180°C for 3h-8h.

[0061] The aluminum-copper-magnesium alloy of the present invention is designed with reasonable alloy composition and precisely controlled preparation process parameters, thereby reducing the cost of the prepared aluminum-copper-magnesium alloy and exhibiting good mechanical properties at both room temperature and high temperature of 300°C. By increasing the Mg element concentration to a Cu / Mg mass ratio of 2 to 4, the present invention can significantly promote the formation of the Al2Cu(Ω) high-temperature stable phase, ensuring that the alloy still has high strength at 300°C. The introduction of Mn and Zr elements reduces the diffusion rate of Cu in the matrix Al, delays the precipitation process of the aluminum-copper supersaturated solid solution at high temperature, and ensures that the alloy has higher mechanical properties at high temperature. The addition of refining elements such as Ti and Sc exerts grain refinement strengthening. At the same time, the rare earth Sc element is enriched at the grain boundaries to form refractory and stable intermetallic compounds with Al, Cu, Mn, etc., which are distributed along the grains and between dendrites to form a hard skeleton, effectively hindering grain boundary sliding and creep deformation at room temperature and high temperature, further improving the room temperature and high temperature mechanical properties of the alloy. The present invention fully dissolves the cast Al2Cu precipitated phase into the matrix through a two-stage solid solution process; and controls the dispersion precipitation of the Al2Cu(Ω) high-temperature stable phase through an aging heat treatment process, thereby further improving the room temperature and high-temperature mechanical properties of the alloy.

[0062] The aluminum-copper-magnesium alloy prepared by the above preparation method has a primary α-Al matrix in the as-cast structure, with white Al2Cu and Al2CuMg phases and some Sc-rich intermetallic phases precipitating at the grain boundaries. The area fraction of the precipitated phases at the grain boundaries accounts for approximately 10-20%. After heat treatment, the Al2Cu and Al2CuMg phases at the grain boundaries are largely dissolved in the matrix, and the high-temperature stable Al2Cu(Ω) phase is dispersed and precipitated during aging.

[0063] It should be noted that most existing aluminum-copper-magnesium alloys promote the formation of the high-temperature stable Al2Cu phase Ω by adding Ag. This element has a high additive cost, which increases the alloy's production cost. Compared to existing aluminum-copper-magnesium alloys, the method of the present invention introduces a higher concentration of Mg. The industry average cost of raw magnesium smelting is approximately 19,000 yuan / ton, significantly reducing the production cost of aluminum-copper-magnesium alloys. Furthermore, the relative density of Mg is only 1.74g / cm3, offering significant lightweighting advantages.

[0064] The aluminum-copper-magnesium alloy prepared by the present invention has high mechanical properties at both room temperature and high temperature of 300°C. At room temperature, the aluminum-copper-magnesium alloy prepared by the present invention has a yield strength of ≥280 MPa (e.g., 282-295 MPa), a tensile strength of ≥400 MPa (e.g., 412-430 MPa), and an elongation of ≥8% (e.g., 8.0-8.2%). At a high temperature of 300°C, the aluminum-copper-magnesium alloy prepared by the present invention has a yield strength of ≥120 MPa (e.g., 120-130 MPa), a tensile strength of ≥150 MPa (e.g., 155-165 MPa), and an elongation of ≥13% (e.g., 13.0-13.2%).

[0065] The advantages of the present invention in precisely controlling the chemical composition, content and preparation process parameters of the elements will be demonstrated below with specific examples.

[0066] Example 1

[0067] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this embodiment has the following components by mass percentage: Cu: 4.94%, Mg: 1.84%, Mn: 0.79%, Ti: 0.1%, Zr: 0.22%, Sc: 0.33%; Fe: 0.08%; the balance being aluminum and unavoidable impurities.

[0068] The mass ratio of Cu / Mg is 2.68.

[0069] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0070] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0071] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 750°C for 40 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 750°C. After they are completely melted, they are kept at this temperature for 40 minutes. After the temperature drops to the second melting temperature of 730°C, a pure magnesium block is pressed in with a pressing spoon;

[0072] S3: After adding the alloying elements, the refining and degassing are carried out, the mixture is allowed to stand for 20 minutes, and the slag is removed;

[0073] S4: gravity casting, pouring at 690℃, mold temperature kept at 150℃;

[0074] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0075] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching, and kept at 160℃ for 8 hours.

[0076] The aluminum-copper-magnesium alloy prepared in this embodiment has a yield strength of 282 MPa, a tensile strength of 412 MPa, and an elongation of 8.0% at room temperature; a yield strength of 120 MPa, a tensile strength of 155 MPa, and an elongation of 13% at 300°C.

[0077] Example 2

[0078] The high-strength, heat-resistant aluminum-copper-magnesium alloy of this embodiment has the following components by mass percentage: Cu: 5.12%, Mg: 2.32%, Mn: 0.41%, Ti: 0.25%, Zr: 0.15%, Sc: 0.30%, Fe: 0.08%, and the balance is aluminum and unavoidable impurities.

[0079] The mass ratio of Cu / Mg is 2.21.

[0080] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0081] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0082] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 780°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 780°C. After they are completely melted, they are kept at this temperature for 30 minutes. After the temperature drops to the second melting temperature of 710°C, a pure magnesium block is pressed in with a pressing spoon;

[0083] S3: After adding all the alloy elements, the process is refined and degassed, left to stand for 30 minutes, slag removed, and poured;

[0084] S4: Gravity casting; pouring at 670°C, mold temperature maintained at 180°C;

[0085] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0086] Among them, the solution treatment is a secondary solution treatment, which is kept at 510℃ for 3 hours, then kept at 520℃ for 8 hours, and then aged after quenching at 175℃ for 5 hours.

[0087] The aluminum-copper-magnesium alloy prepared in this embodiment has a yield strength of 295 MPa, a tensile strength of 430 MPa, and an elongation of 8.2% at room temperature; a yield strength of 130 MPa, a tensile strength of 165 MPa, and an elongation of 13.2% at 300°C.

[0088] Comparative Example 1

[0089] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 4.26%, Mg: 0.34%, Mn: 0.4%, Ti: 0.25%, Zr: 0.15%, Sc: 0.31%; Fe: 0.06%; the balance being aluminum and unavoidable impurities.

[0090] The mass ratio of Cu / Mg is 12.53.

[0091] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0092] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0093] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 780°C for 20 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 780°C. After they are completely melted, they are kept at this temperature for 20 minutes. After the temperature drops to the second melting temperature of 730°C, a pure magnesium block is pressed in with a pressing spoon;

[0094] S3: After adding all alloy elements, refining and degassing are carried out, standing for 30 minutes, and slag removal;

[0095] S4: gravity casting, pouring at 670℃, mold temperature kept at 150℃;

[0096] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0097] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching at 175℃ for 5 hours.

[0098] The aluminum-copper-magnesium alloy prepared in this comparative example has a yield strength of 191 MPa, a tensile strength of 323 MPa, and an elongation of 8.5% at room temperature; a yield strength of 94 MPa, a tensile strength of 117 MPa, and an elongation of 15% at 300°C.

[0099] Comparative Example 2

[0100] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 6.13%, Mg: 0.31%, Mn: 0.42%, Ti: 0.26%, Zr: 0.15%, Sc: 0.30%; Fe: 0.06%; the balance being aluminum and unavoidable impurities.

[0101] The mass ratio of Cu / Mg is 19.77.

[0102] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0103] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0104] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 750°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 750°C. After they are completely melted, they are kept at this temperature for 30 minutes. After the temperature drops to the second melting temperature of 730°C, a pure magnesium block is pressed in with a pressing spoon;

[0105] S3: After adding all the alloy elements, the process is refined and degassed, left to stand for 30 minutes, slag removed, and poured;

[0106] S4: Gravity casting; pouring at 690℃, mold temperature kept at 150℃;

[0107] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0108] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching at 175℃ for 5 hours.

[0109] The aluminum-copper-magnesium alloy prepared in this comparative example has a yield strength of 312 MPa, a tensile strength of 352 MPa, and an elongation of 9.0% at room temperature; a yield strength of 117 MPa, a tensile strength of 140 MPa, and an elongation of 14% at 300°C.

[0110] Comparative Example 3

[0111] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 4.87%, Mg: 1.03%, Mn: 0.41%, Ti: 0.27%, Zr: 0.15%, Sc: 0.30%; Fe: 0.05%; the balance being aluminum and unavoidable impurities.

[0112] The mass ratio of Cu / Mg is 4.73.

[0113] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0114] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0115] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 780°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 780°C. After they are completely melted, they are kept at this temperature for 30 minutes. After the temperature drops to the second melting temperature of 710°C, a pure magnesium block is pressed in with a pressing spoon;

[0116] S3: After adding all alloy elements, refining and degassing are carried out, standing for 30 minutes, and slag removal;

[0117] S4: Gravity casting; pouring at 670°C, mold temperature maintained at 180°C;

[0118] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0119] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching at 175℃ for 5 hours.

[0120] The aluminum-copper-magnesium alloy prepared in this comparative example has a yield strength of 225 MPa, a tensile strength of 338 MPa, and an elongation of 8.0% at room temperature; a yield strength of 121 MPa, a tensile strength of 141 MPa, and an elongation of 10.0% at 300°C.

[0121] Comparative Example 4

[0122] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 5.0%, Mg: 1.87%, Mn: 0.43%, Ti: 0.36%, Zr: 0.15%, Sc: 0.30%; Fe: 0.5%; the balance being aluminum and unavoidable impurities;

[0123] The mass ratio of Cu / Mg is 2.67.

[0124] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0125] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0126] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 780°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 780°C. After they are completely melted, they are kept at this temperature for 30 minutes. After the temperature drops to the second melting temperature of 710°C, a pure magnesium block is pressed in with a pressing spoon;

[0127] S3: After adding all alloy elements, refining and degassing are carried out, standing for 30 minutes, and slag removal;

[0128] S4: Gravity casting; pouring at 670℃, mold temperature kept at 150℃;

[0129] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0130] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching at 175℃ for 5 hours.

[0131] The aluminum-copper-magnesium alloy prepared in this comparative example has a room-temperature yield strength of 210 MPa, a tensile strength of 300 MPa, and an elongation of 4.0%; a yield strength of 110 MPa, a tensile strength of 125 MPa, and an elongation of 7.0% at 300°C.

[0132] Comparative Example 5

[0133] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 4.94%, Mg: 1.84%, Mn: 0.79%, Ti: 0.1%, Zr: 0.22%, Sc: 0.33%; Fe: 0.08%; the balance being aluminum and unavoidable impurities.

[0134] The mass ratio of Cu / Mg is 2.68.

[0135] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0136] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0137] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first melting temperature of 750°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continue to be smelted at 750°C. After they are completely melted, they are kept at this temperature for 30 minutes. After the temperature drops to the second melting temperature of 730°C, a pure magnesium block is pressed in with a pressing spoon;

[0138] S3: After adding the alloying elements, the refining and degassing are carried out, the mixture is allowed to stand for 20 minutes, and the slag is removed;

[0139] S4: Gravity casting; pouring at 670℃, mold temperature kept at 150℃;

[0140] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0141] Among them, the solution treatment is a secondary solution treatment, which is kept at 470℃ for 2h, then kept at 480℃ for 8h, and then aged after quenching at 170℃ for 18h.

[0142] The aluminum-copper-magnesium alloy prepared in this comparative example has a yield strength of 273 MPa, a tensile strength of 323 MPa, and an elongation of 2.5% at room temperature; a yield strength of 114 MPa, a tensile strength of 116 MPa, and an elongation of 10% at 300°C.

[0143] Comparative Example 6

[0144] The high-strength and heat-resistant aluminum-copper-magnesium alloy of this comparative example has the following components by mass percentage: Cu: 5.0%, Mg: 1.80%, Mn: 0.61%, Ti: 0.3%, Zr: 0.30%, Sc: 0.33%; Fe: 0.10%; the balance being aluminum and unavoidable impurities.

[0145] The mass ratio of Cu / Mg is 2.78.

[0146] The method for preparing the above-mentioned high-strength heat-resistant aluminum-copper-magnesium alloy comprises the following steps:

[0147] S1: According to the mass percentage of each element, weigh pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy, a total of 30 kg as raw materials;

[0148] S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and smelting them at a first smelting temperature of 780°C for 30 minutes. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and smelted at 780°C. After they are completely melted, they are kept warm for 30 minutes. At a second smelting temperature of 780°C, pure magnesium blocks are pressed in with a pressing spoon;

[0149] S3: After adding all the alloy elements, the refining and degassing are carried out, the mixture is allowed to stand for 60 minutes, and the slag is removed;

[0150] S4: Gravity casting, pouring at 730℃, mold temperature kept at 150℃;

[0151] S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

[0152] Among them, the solution treatment is a secondary solution treatment, which is kept at 500℃ for 4 hours, then kept at 520℃ for 6 hours, and then aged after quenching at 175℃ for 5 hours.

[0153] The aluminum-copper-magnesium alloy prepared in this embodiment has a yield strength of 262 MPa, a tensile strength of 380 MPa, and an elongation of 7.0% at room temperature; a yield strength of 105 MPa, a tensile strength of 128 MPa, and an elongation of 12% at 300°C.

[0154] Table 1 Chemical composition of the alloys of the embodiment and the comparative example (wt, %)

[0155] serial number Cu Mg Mn Ti Zr Sc Fe Example 1 4.94 1.84 0.79 0.10 0.22 0.33 0.08 Example 2 5.12 2.32 0.41 0.25 0.15 0.30 0.08 Comparative Example 1 4.26 0.34 0.40 0.25 0.15 0.31 0.06 Comparative Example 2 6.13 0.31 0.42 0.26 0.15 0.30 0.06 Comparative Example 3 4.87 1.03 0.41 0.27 0.15 0.30 0.05 Comparative Example 4 5.0 1.87 0.43 0.36 0.15 0.30 0.5 Comparative Example 5 4.94 1.84 0.79 0.10 0.22 0.33 0.08 Comparative Example 6 5.0 1.8 0.61 0.3 0.3 0.33 0.1

[0156] Table 2 Preparation process of alloys in Examples and Comparative Examples

[0157]

[0158]

[0159] Table 3 Mechanical properties of the alloys of the examples and comparative examples

[0160]

[0161] It can be seen from the comparative examples and embodiments that the alloy element composition or content of comparative examples 1-4 does not meet the requirements of the present invention. Among them, the addition amounts of Cu and Mg in comparative examples 1-3 do not meet the requirements of the present invention, excessive Fe element is added in comparative example 4, the heat treatment system in comparative example 5 does not meet the requirements of the present invention, and in comparative example 6, too high addition temperature and too long standing time are used in the process of adding Mg. As a result, the yield strength, tensile strength and elongation of the castings in the cast and heat-treated conditions are reduced to varying degrees compared with the embodiments.

[0162] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A high-strength, heat-resistant aluminum-copper-magnesium alloy, characterized in that: The alloy components are as follows by mass percentage: Cu: 4.5-5.5%, Mg: 1.84-2.5%, Mn: 0.2-1.0%, Ti: 0.1-0.5%, Zr: 0.22-0.5%, Sc: 0.1-0.5%; Fe: 0-0.1%; the balance is aluminum and unavoidable impurities; In the alloy composition, the mass ratio of Cu / Mg is 2 to 2.68; The matrix of the aluminum-magnesium-copper alloy in the cast structure is primary α-Al, white Al2Cu and Al2CuMg phases and some Sc-rich intermetallic phases are precipitated at the grain boundaries, and the area fraction of the precipitated phases at the grain boundaries accounts for 10-20%. After heat treatment, the Al2Cu and Al2CuMg phases at the grain boundaries are basically dissolved in the matrix, and the Al2Cu high-temperature stable phase is dispersed and precipitated in the aging state; The aluminum-magnesium-copper alloy is prepared by the following steps: S1: According to the mass percentage of each element, pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy are weighed as raw materials respectively; S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first smelting temperature. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continued to be smelted at the first smelting temperature. Keeping the temperature, after the temperature drops to the second smelting temperature, pure magnesium blocks are pressed in with a pressing spoon; S3: After all alloying elements are added, refining and degassing are carried out, standing and slag removal is carried out; S4: casting; S5: performing solid solution and aging treatment on the cast alloy to obtain a finished alloy product; The first melting temperature is 750-800°C, and the second melting temperature is 700-730°C; At a high temperature of 300° C., the aluminum-copper-magnesium alloy has a yield strength of ≥120 MPa, a tensile strength of ≥150 MPa, and an elongation of ≥13%.

2. The aluminum-copper-magnesium alloy according to claim 1, characterized in that The alloy components are as follows by mass percentage: Cu: 4.94-5.12%, Mg: 1.84-2.32%, Mn: 0.41-0.79%, Ti: 0.1-0.25%, Zr: 0.15-0.22%, Sc: 0.3-0.33%; Fe: 0-0.08%; the balance is aluminum and unavoidable impurities.

3. The aluminum-copper-magnesium alloy according to claim 1, characterized in that In the alloy components, the mass ratio of Cu / Mg is 2.20-2.

68.

4. A method for preparing a high-strength, heat-resistant aluminum-copper-magnesium alloy, for preparing the aluminum-copper-magnesium alloy according to any one of claims 1 to 3, characterized in that: The steps include: S1: According to the mass percentage of each element, pure Al, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Zr master alloy, and Al-Sc master alloy are weighed as raw materials respectively; S2: Smelting begins, adding pure aluminum ingots, Al-Mn master alloys, and Al-Cu master alloys to the resistance furnace and keeping them at the first smelting temperature. After they are completely melted, Al-Ti master alloys, Al-Zr master alloys, and Al-Sc master alloys are added and continued to be smelted at the first smelting temperature. Keeping the temperature, after the temperature drops to the second smelting temperature, pure magnesium blocks are pressed in with a pressing spoon; S3: After all alloying elements are added, refining and degassing are carried out, standing, and slag removal is carried out; S4: casting; S5: subjecting the cast alloy to solid solution and aging treatment to obtain a finished alloy product.

5. The preparation method according to claim 4, characterized in that In step S2, the first smelting temperature is 780-800°C, and the holding time is 30-60 minutes.

6. The preparation method according to claim 5, characterized in that In step S2, the second smelting temperature is 710-730°C.

7. The preparation method according to claim 6, characterized in that In step S3, the mixture is allowed to stand for 20-30 minutes.

8. The preparation method according to claim 7, characterized in that In step S4, the casting process is gravity or low-pressure casting, the pouring temperature is 670-690°C, and the mold insulation temperature is 150-200°C.

9. The preparation method according to claim 8, characterized in that In step S5, the solution treatment is a two-stage solution treatment, which is carried out at 490-510° C. for 2 h to 5 h, and then at 510-540° C. for 5 h to 10 h.

10. The preparation method according to claim 9, characterized in that In step S5, the aging treatment temperature is 150-180° C., and the holding time is 3 h to 8 h.

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