Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy and preparation method thereof

Abstract

The invention discloses an Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy and a preparation method thereof. The aluminum alloy is prepared from the following components in percentage by mass: 1.0 to 9.0 weight percent of copper, 0.1 to 1.0 weight percent of manganese, 0.01 to 0.5 weight percent of zirconium, 0.1 to 1.5 weight percent of nickel, 0 to 0.45 weight percent of scandium, 0.1 to 0.6 weight percent of titanium, 0.01 to 0.45 weight percent of vanadium, 0.01 to 0.4 weight percent of cadmium, 0.001 to 0.08 weight percent of boron, less than or equal to 0.15 weight percent of iron, less than or equal to 0.15 weight percent of silicon, less than or equal to 0.15 weight percent of magnesium and the balance of aluminum. The preparation method comprises the steps of raw material preparation, smelting, casting, heat treatment and the like. According to the invention, the technical problems of low high-temperature strength, high manufacturing cost and the like of the traditional cast Al-Cu alloy under the high-temperature service condition can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-resistant aluminum alloys, in particular to an Al-Cu-Mn-Zr-Ni series high-strength heat-resistant casting aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is a lightweight alloy formed by adding alloying elements to an aluminum matrix. It is widely used in aerospace, military, automotive, and chemical industries due to its advantages such as low density, high strength, and good casting properties. With the improvement of the global economic development level, the industrial field has increasingly stringent requirements on the various properties of aluminum alloys, especially for harsh service environments such as high temperature and high pressure. However, existing commercial aluminum alloys cannot meet the service conditions under existing harsh environmental conditions, so the demand for the preparation of high-performance aluminum alloys has been focused on by various fields.

[0003] Cast heat-resistant aluminum alloys have good high-temperature oxidation resistance, high-temperature creep resistance and high-temperature strength. However, the high-temperature performance of traditional cast aluminum alloys at 300°C and 350°C is currently close to the limit state, and cannot meet the long-term high-temperature service requirements of current aerospace and automotive engine materials. For example, as a key structural component in the engine combustion chamber, the piston needs to withstand thermomechanical fatigue operations at 25-300°C and needs to serve for a long time at 300-350°C. The strength and performance of a piston that has been in service under high-temperature conditions for a long time will drop significantly over time, thereby limiting its scope of application.

[0004] Al-Cu alloys are widely used in the aerospace and military fields. They have the advantages of high specific strength, high specific stiffness, and good high temperature resistance. Widely used 2-series heat-treatable aluminum alloys such as ZL201, ZL205A, ZL207, 2219, 2618, etc. have the above advantages. However, when the service temperature is higher than 250℃, the main strengthening phase of the alloy is θ'-Al 2 The Cu phase will rapidly coarsen and grow, transforming into the θ-Al phase which has an incoherent relationship with the α-Al matrix. 2 Cu phase, which deteriorates the high temperature performance of the alloy and severely limits the application range of Al-Cu alloys.

[0005] Microalloying is one of the means to improve the performance of aluminum alloys. When an appropriate amount of Ni is added to the Al-Cu alloy, the Ni element forms an Al-Cu-Ni intermetallic compound in the alloy. This phase has good thermal stability under high temperature conditions and is not easy to decompose. The fine Al-Cu-Ni intermetallic compound will also be evenly dispersed at the grain boundary, which can effectively improve the grain boundary strength. At the same time, the alloying of Ni will also inhibit the grain and θ'-Al 2The growth of Cu phase effectively improves the high temperature strength of the alloy.

[0006] Chinese patent CNIO4862563A discloses a method for preparing a high-strength aluminum-copper alloy for structural parts in the aerospace field, whose composition is Cu: 2.6-3.5%; Mn: 0.1-0.25%; Fe: 0.1-0.8%; Mg: <1.3-1.8%; Zr: 0.1-0.25%; Ni: 0.1-0.8%, Nb: 0.01-0.5%, and the balance is Al. The high-strength aluminum-copper alloy is prepared through the steps of batching and preheating, smelting, aluminum liquid treatment, adding intermediate alloy, casting, solution quenching and aging treatment. According to the document, its yield strength at 350°C reaches more than 287MPa and its tensile strength reaches 309MPa, but the performance of the aluminum-copper alloy at a high temperature of 300°C is not disclosed.

[0007] A Chinese patent CN 115821130 B discloses a method for preparing a high-strength aluminum-copper alloy for structural parts in the aerospace field. According to the document, its tensile strength reaches more than 132MPa at 300°C and 64MPa at 350°C. However, the alloy also uses expensive precious metal Ag and rare earth element Sc, which increases the cost of the alloy.

[0008] In summary, how to reduce the production cost of Al-Cu alloys while improving the high-temperature performance of aluminum alloys and expanding their application areas has become a key issue restricting the current development of Al-Cu alloys. Summary of the invention

[0009] To this end, the technical problem to be solved by the present invention is to provide an Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy and a preparation method thereof, so as to solve the technical problems of low high-temperature strength and high cost of traditional cast Al-Cu series alloys under high-temperature service conditions.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0011] An Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy is composed of the following components in mass fraction: 1.0-9.0wt% copper, 0.1-1.0wt% manganese, 0.01-0.5wt% zirconium, 0.1-1.5wt% nickel, 0-0.45wt% scandium, 0.1-0.6wt% titanium, 0.01-0.45wt% vanadium, 0.01-0.4wt% cadmium, 0.001-0.08wt% boron, iron content is less than or equal to 0.15wt%, silicon content is less than or equal to 0.15wt%, magnesium content is less than or equal to 0.15wt%, and the balance is aluminum.

[0012] At room temperature and high temperature, adding strengthening element Cu to aluminum alloy can increase the strength of aluminum alloy. With the increase of Cu content, the strength of alloy increases continuously. When the Cu content in alloy reaches about 5wt%, the strength of alloy approaches the maximum value. In addition, Cu element can also effectively improve the welding performance of alloy.

[0013] Mn can effectively improve the high temperature performance of the alloy, increase the activation energy of atoms in the solid solution, and reduce the diffusion coefficient of solute atoms and the decomposition rate of the solid solution. 20 Cu 2 Mn 3 The phase can exist stably at temperatures below 400°C and is not easy to agglomerate and grow under high temperature conditions, thereby significantly improving the high temperature resistance of aluminum alloys. However, if the Mn content is too high, it will lead to T-Al 20 Cu 2 Mn 3 The increase of phases increases the interface and accelerates the diffusion, which reduces the high temperature resistance of the alloy.

[0014] Zr can effectively improve the alloy recrystallization temperature and solid solution stability, while the generated dispersed high heat resistant Al 3 Zr can further improve the high temperature resistance of the alloy;

[0015] Ni in aluminum alloy is mainly in the form of ε-Al 3 Ni, δ-Al 3 CuNi, γ-Al 7 Cu 4 It exists in the form of intermetallic compounds such as Ni, which can effectively pin the grain boundaries under high temperature conditions, hinder the movement of dislocations, and increase the grain boundary strength of the alloy, thereby effectively improving the high temperature performance of the alloy;

[0016] Sc element can interact with Zr element in copper-aluminum alloy to form high temperature resistant core-shell structure strengthening phase Al 3 (Sc, Zr), which can significantly improve the room temperature and high temperature mechanical properties of the alloy; secondly, some Sc elements will segregate in Al 2 On the Cu phase surface, according to the solute drag effect principle, under high temperature conditions, the segregation of Sc will greatly reduce the Al 2 The coarsening rate of Cu phase slows down the Al 2 The transformation rate of the metastable phase of the Cu phase to the stable phase is increased, thereby significantly improving the room temperature and high temperature mechanical properties of the copper-aluminum alloy.

[0017] Ti can increase the recrystallization temperature of the alloy, reduce the decomposition tendency of supersaturation and solid solution, and keep the alloy structure stable under high temperature conditions. 3The extremely low mismatch between Ti and the α-Al matrix can effectively refine the cast grains, thereby improving the alloy properties.

[0018] V can effectively increase the alloy recrystallization temperature and inhibit the alloy recrystallization process. At the same time, the addition of V can effectively refine the alloy grains. Adding an appropriate amount of V can significantly improve the fluidity of the Al-Cu alloy and help reduce the alloy's thermal cracking tendency.

[0019] During the aging process, Cd will combine with the vacancies in the alloy to promote the formation of θ'-Al 2 The precipitation of Cu phase makes the second phase more dispersed, thereby improving the strength of the aluminum alloy;

[0020] B can effectively refine the alloy microstructure, promote grain refinement and thus improve the heat resistance of the alloy. B and Al form AlB 2 Phase, AlB 2 A large amount of heat is generated during the phase transformation, which can effectively strengthen the aluminum alloy. This strengthening effect helps to improve the heat resistance of aluminum alloys. B can reduce the liquidus temperature of the alloy and improve the liquid fluidity of the alloy, thereby improving the casting performance. Good casting performance helps to produce more dense and uniform aluminum alloy parts, thereby improving its heat resistance. Boron can significantly improve the hardness and tensile strength of aluminum alloys, which helps to enhance the mechanical properties of aluminum alloys at high temperatures, thereby improving its heat resistance; B can also work synergistically with Ni or Sc to effectively refine the alloy microstructure, which is beneficial to improve the room temperature and high temperature mechanical properties of aluminum alloys.

[0021] Under the alloy design of the present invention, the above-mentioned alloy elements can fully exert their synergistic effects and effectively improve the room temperature and high temperature mechanical properties of the aluminum alloy.

[0022] The preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy comprises the following steps:

[0023] Step (1), preparing alloy raw materials according to the content of each metal element in the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy designed above;

[0024] Step (2), heating the alloy raw material in a muffle furnace and performing heat preservation treatment; placing the alloy raw material after heat preservation treatment in a preheated smelting furnace for smelting to obtain alloy liquid;

[0025] Step (3), casting the alloy liquid into a preheated metal mold (a ductile iron mold) to obtain an aluminum alloy ingot;

[0026] Step (4), heat treating the aluminum alloy ingot. After the heat treatment, an Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy can be obtained.

[0027] The present invention adds nickel or nickel and scandium as a modifier to the Al-Cu-Mn aluminum alloy to improve the high temperature strength of the aluminum alloy. By controlling the content of alloy elements such as copper, manganese, zirconium, titanium, vanadium, cadmium and boron in the copper-aluminum alloy, the elements can fully exert synergistic effects under the preparation process conditions of the present invention, so that more ε-Al can be formed in the aluminum alloy. 3 Ni, δ-Al 3 CuNi, γ-Al 7 Cu 4 Ni、Al 3 (Sc, Zr), Al 3 Zr, T-Al 20 Cu 2 Mn 3 High temperature stability strengthening phases are formed, thereby significantly improving the high temperature strength of Al-Cu-Mn aluminum alloys. Since the amount of scandium used in nickel or nickel and scandium as a modifier is relatively small compared with scandium alone as a modifier, the economic cost of copper-aluminum alloys can be greatly reduced. The instantaneous tensile properties of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy prepared by the method of the present invention after heat exposure at 300°C for 30 minutes: yield strength greater than 150MPa, tensile strength greater than 200MPa, and elongation not less than 6%; the instantaneous tensile properties after heat exposure at 350°C for 30 minutes: yield strength not less than 130MPa, tensile strength greater than 175MPa, and elongation not less than 4%, which can meet the mechanical property requirements of materials in the aerospace field.

[0028] The preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (1), the components of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy are prepared as alloy raw materials according to the following contents: copper 4.6-5.4wt%, manganese 0.1-0.5wt%, zirconium 0.1-0.4wt%, nickel 0.1-0.5wt%, titanium 0.1-0.4wt%, vanadium 0.1-0.3wt%, cadmium 0.01-0.03wt%, boron 0.001-0.003wt%, iron content less than or equal to 0.15wt%, silicon content less than or equal to 0.15wt%, magnesium content less than or equal to 0.15wt%, and the balance is aluminum;

[0029] The alloy raw materials are pure aluminum ingots, pure cadmium and master alloy raw materials; the master alloy raw materials are aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-titanium master alloys, aluminum-vanadium master alloys, aluminum-titanium-boron master alloys, aluminum-zirconium master alloys and aluminum-nickel master alloys; the purity of the pure aluminum ingot is greater than or equal to 99.7wt%, the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper master alloy is Al-50Cu alloy (the mass fraction of copper is 50wt%), the aluminum-manganese master alloy is Al-10Mn alloy (the mass fraction of manganese is 10wt%), the aluminum-titanium master alloy is Gold is Al-5Ti alloy (mass fraction of titanium is 5wt%), aluminum-vanadium master alloy is Al-5V alloy (mass fraction of vanadium is 5wt%), aluminum-titanium-boron master alloy is Al-5Ti-B alloy (mass fraction of titanium is 5wt%, mass fraction of boron is 1wt%), aluminum-zirconium master alloy is Al-5Zr alloy (mass fraction of zirconium is 5wt%), aluminum-nickel master alloy is Al-10Ni alloy (mass fraction of nickel is 10wt%); impurity contents in the master alloy raw materials are all less than or equal to 0.1wt%.

[0030] In the method for preparing the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (4), the heat treatment comprises the following steps:

[0031] Step (4-1) first stage heat treatment: heating the aluminum alloy ingot to 350-450°C at a rate of 5-10°C / min, and keeping it at 350-450°C for 4-8h, then heating it to 500-550°C at a rate of 5-10°C / min, and keeping it at 500-550°C for 4-8h; then transferring the aluminum alloy ingot to water at 50-80°C for water quenching for 1-10s, and then naturally cooling it to room temperature;

[0032] Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 130-190°C at a rate of 5-10°C / min, kept at 130-190°C for 4-8h, and then naturally cooled to room temperature.

[0033] In the first stage heat treatment of the present invention, the Zr, Ti and Ni elements in the aluminum alloy ingot are rapidly nucleated to form high temperature resistant Al 3 Zr、Al 3 Ni、Al 3 Ti、Al 3 (Zr, Ti) or Al 3(Cu, Ni) phase, heating to 500-550°C at a rate of 5-10°C / min and keeping in this temperature range for 4-8h can make the maximum content of the main strengthening element Cu in the aluminum alloy ingot dissolved in the microstructure; the above-mentioned second-stage heat treatment process can make the main strengthening phase θ'-Al 2 The Cu phase precipitates rapidly due to the θ'-Al 2 The Cu phase has a coherent relationship with the matrix, and some nickel elements can segregate in the θ'-Al 2 Cu phase interface and inhibit the θ'-Al 2 The Cu phase coarsens and grows under high temperature conditions, thereby effectively increasing the θ'-Al 2 Heat resistance of Cu phase. Therefore, the two-step heat treatment method of the present invention can fully exert the synergistic effect between the strengthening phases and effectively improve the room temperature and high temperature mechanical properties of the aluminum alloy.

[0034] In the preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (2), the conditions for the heat preservation treatment of the alloy raw material are: heat preservation at a temperature of 200-300°C for 2-3 hours; the preheating temperature of the melting furnace is 450-500°C, and the preheating time is 2-3 hours; the melting temperature is 600-740°C;

[0035] The melting sequence of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, one alloy raw material is fully melted before adding the next alloy raw material; the melting sequence can effectively avoid the element burnout generated during the melting process, ensure the accurate content ratio of each alloy element, so that the synergistic effect between the alloy elements can be fully exerted to effectively improve the room temperature and high temperature mechanical properties of the aluminum alloy.

[0036] After all the alloy raw materials are melted, stir them thoroughly and remove the slag, then add the C wrapped in aluminum foil. 6 Cl 6 The refining agent powder is refined for 10 to 40 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection during the refining process; after the refining is completed, the temperature is kept at 700 to 760° C. for 20 to 30 minutes, and after the heat preservation, a first slag removal treatment after refining, stirring and a second slag removal treatment after refining are sequentially performed, and an alloy liquid is obtained after the second slag removal treatment after refining;

[0037] In step (3), the casting temperature of the alloy liquid is 710-740°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 100-300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent.

[0038] The preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (1), prepare alloy raw materials according to the following contents of each component of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy: 5.1wt% copper, 0.4wt% manganese, 0.15wt% zirconium, 0.5wt% nickel, 0.15wt% titanium, 0.15wt% vanadium, 0.03wt% cadmium, 0.0025wt% boron, iron content less than or equal to 0.1wt%, silicon content less than or equal to 0.05wt%, magnesium content less than or equal to 0.05wt%, and the balance is aluminum;

[0039] In step (2), the conditions for heat preservation of the alloy raw material are: heat preservation at 200°C for 2 hours; preheating temperature of the smelting furnace is 450°C, and the preheating time is 2 hours; smelting temperature is 740°C;

[0040] The melting order of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, one alloy raw material is fully melted before adding the next alloy raw material;

[0041] After all the alloy raw materials are melted, stir them thoroughly and remove the slag, then add the C wrapped in aluminum foil. 6 Cl 6 The refining agent powder is refined for 10 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection during the refining process; after the refining is completed, the temperature is kept at 730°C for 20 minutes, and after the heat preservation, the refining first slag removal treatment, stirring and refining second slag removal treatment are carried out in sequence, and the alloy liquid is obtained after the second slag removal treatment after refining;

[0042] In step (3), the casting temperature of the alloy liquid is 710°C, and the casting time is controlled within 15 seconds; the preheating temperature of the metal mold is 200°C, and boron nitride is sprayed inside the metal mold cavity as a release agent;

[0043] In step (4), the heat treatment comprises the following steps:

[0044] Step (4-1) first stage heat treatment: the aluminum alloy ingot is heated to 350°C at a rate of 5°C / min and kept at 350°C for 8h, then heated to 500°C at a rate of 10°C / min and kept at 500°C for 4h; then the aluminum alloy ingot is transferred to 60°C water for water quenching for 5s, and then naturally cooled to room temperature;

[0045] Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 130°C at a rate of 5°C / min, kept at 130°C for 4 hours, and then naturally cooled to room temperature.

[0046] The preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy, in step (1), the components of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy are prepared as alloy raw materials according to the following contents: copper 1.0-9.0wt%, manganese 0.1-1.0wt%, zirconium 0.01-0.5wt%, nickel 0.1-1.5wt%, scandium 0.05-0.45wt%, titanium 0.1-0.6wt%, vanadium 0.01-0.45wt%, cadmium 0.1-0.4wt%, boron 0.005-0.08wt%, iron content less than or equal to 0.15wt%, silicon content less than or equal to 0.15wt%, magnesium content less than or equal to 0.15wt%, and the balance is aluminum;

[0047] The alloy raw materials are pure aluminum ingots, pure cadmium and intermediate alloy raw materials; the intermediate alloy raw materials are aluminum-copper intermediate alloys, aluminum-manganese intermediate alloys, aluminum-titanium intermediate alloys, aluminum-vanadium intermediate alloys, aluminum-titanium-boron intermediate alloys, aluminum-zirconium intermediate alloys, aluminum-nickel intermediate alloys and aluminum-scandium intermediate alloys; the purity of the pure aluminum ingots is greater than or equal to 99.7wt%, and the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper intermediate alloy is Al-50Cu alloy, the aluminum-manganese intermediate alloy is Al-10Mn alloy, the aluminum-titanium intermediate alloy is Al-5Ti alloy, the aluminum-vanadium intermediate alloy is Al-5V alloy, the aluminum-titanium-boron intermediate alloy is Al-5Ti-B alloy, the aluminum-zirconium intermediate alloy is Al-5Zr alloy, the aluminum-nickel intermediate alloy is Al-10Ni alloy, and the aluminum-scandium intermediate alloy is Al-2Sc alloy (the mass fraction of scandium is 2wt%); and the impurity content in the intermediate alloy raw materials is less than or equal to 0.1wt%.

[0048] In the method for preparing the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (4), the heat treatment comprises the following steps:

[0049] Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 350-450°C at a rate of 5-10°C / min, and keeping it at 350-450°C for 2-3h; homogenization treatment can eliminate residual stress and defects in the aluminum alloy ingot and optimize the overall microstructure and performance of the aluminum alloy; specifically, homogenization treatment can reduce the dendrite segregation and regional segregation problems generated during the casting process, which will lead to a decrease in the internal quality of the ingot and affect the subsequent processing performance; through an appropriate homogenization process, the solid solubility of the coarse compound phase in the alloy can be increased, thereby improving the overall performance of the alloy; under the above-mentioned homogenization treatment conditions of the present invention, the added scandium can be in the aluminum alloy structure as Al3 The (Sc, Zr) strengthening phase is fully precipitated, thus giving full play to the strengthening effect of scandium;

[0050] Step (4-2) solution treatment: the aluminum alloy ingot after homogenization treatment is immediately heated to 520-540°C at a rate of 5-10°C / min, and kept at 520-540°C for 8-10h, and then water quenched at a temperature of 60-80°C for a time of less than or equal to 10s; then naturally cooled to room temperature; the residual stress and residual deformation of the cast alloy can be effectively removed within the water quenching temperature range; if the water quenching is not performed, the aluminum alloy cannot reach a supersaturated solid solution state, which has an adverse effect on the precipitation of the strengthening phase during the subsequent aging treatment, resulting in deterioration of the mechanical properties of the aluminum alloy;

[0051] Step (4-3) aging treatment: the aluminum alloy ingot after solution treatment is heated to 160-180°C at a rate of 5-10°C / min, and kept at 160-180°C for 8-10 hours; then naturally cooled to room temperature.

[0052] In the preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (2), the conditions for the heat preservation treatment of the alloy raw materials are: heat preservation at a temperature of 200-300°C for 2-3 hours, the purpose of which is to fully dry and remove the moisture and volatile substances on the surface of pure aluminum and the master alloy to prevent the introduction of harmful impurity hydrogen elements during the smelting process; the preheating temperature of the smelting furnace is 450-500°C, and the preheating time is 2-3 hours; the smelting order of the alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy , aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, aluminum-scandium master alloy, pure cadmium and aluminum-titanium-boron master alloy; if the above smelting order is changed, the aluminum alloy element will be burned and oxidized, thereby reducing the effect of the alloy element in the microstructure, thereby reducing the mechanical properties of the alloy; the smelting temperature is 600-740°C, during smelting, wait until one alloy raw material is fully melted before adding the next alloy raw material; after all the alloy raw materials are melted, they are fully stirred and slag-treated, and then C wrapped in aluminum foil is added 6 Cl 6The refining agent powder is refined for 10 to 40 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced during the refining process for protection; after the refining is completed, the temperature is kept at 700 to 760°C for 20 to 30 minutes, and after the insulation is completed, the first slag removal treatment after refining, stirring and the second slag removal treatment after refining are carried out in sequence, and the alloy liquid is obtained after the second slag removal treatment after refining is completed; the purpose of injecting argon during the refining process is to make the alloy composition more uniform and to degas the liquid alloy at the same time; if the refining temperature is too low, the alloy elements in the liquid alloy are easily burned; if the refining temperature is too low, the alloy is not easy to fully melt, resulting in element segregation in the alloy;

[0053] In step (3), the casting temperature of the alloy liquid is 710-740°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 100-300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent.

[0054] The preparation method of the above-mentioned Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, in step (1), the alloy raw material is prepared according to the following content of each component of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy: copper 5.4wt%, manganese 0.4wt%, zirconium 0.1wt%, nickel 0.3wt%, scandium 0.1wt%, titanium 0.3wt%, vanadium 0.2wt%, cadmium 0.15wt%, boron 0.04wt%, iron content is less than or equal to 0.10wt%, silicon content is less than or equal to 0.05wt%, magnesium content is less than or equal to 0.05wt%, and the balance is aluminum;

[0055] In step (2), the conditions for heat preservation of the alloy raw material are: heat preservation at 300°C for 2h; preheating temperature of the smelting furnace is 500°C, and the preheating time is 2h; smelting temperature is 720°C;

[0056] The smelting order of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, aluminum-scandium master alloy, pure cadmium and aluminum-titanium-boron master alloy; during smelting, one alloy raw material is fully melted before adding the next alloy raw material;

[0057] After all the alloy raw materials are melted, stir them thoroughly and remove the slag, then add the C wrapped in aluminum foil. 6 Cl 6 The refining agent powder is refined for 20 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection during the refining process; after the refining is completed, the temperature is kept at 720°C for 30 minutes, and after the heat preservation, the refining first slag removal treatment, stirring and refining second slag removal treatment are sequentially performed, and the alloy liquid is obtained after the second slag removal treatment after refining;

[0058] In step (3), the casting temperature of the alloy liquid is 710°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent;

[0059] In step (4), the heat treatment comprises the following steps:

[0060] Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 350° C. at a rate of 5° C. / min and keeping the temperature at 350° C. for 2 h;

[0061] Step (4-2) solution treatment: heating the aluminum alloy ingot after homogenization treatment to 520°C at a rate of 5°C / min, and keeping it at 520°C for 8h, and then performing water quenching treatment, the water quenching treatment temperature is 70°C, and the water quenching treatment time is equal to 5s; and then naturally cooling to room temperature;

[0062] Step (4-3) Aging treatment: The aluminum alloy ingot after the solution treatment is heated to 160°C at a rate of 5°C / min, and kept at 160°C for 8 hours; then naturally cooled to room temperature.

[0063] The technical solution of the present invention achieves the following beneficial technical effects:

[0064] 1. The present invention adds a specific amount of nickel or nickel and scandium as a modifier to the Al-Cu-Mn aluminum alloy to improve the high temperature strength of the aluminum alloy. By controlling the content of alloying elements such as copper, manganese, zirconium, titanium, vanadium, cadmium and boron in the copper-aluminum alloy, the elements can fully exert their synergistic effect under the preparation process conditions of the present invention, so that more ε-Al can be formed in the aluminum alloy. 3 Ni, δ-Al 3 CuNi, γ-Al 7 Cu 4 Ni、Al 3 (Sc, Zr), Al 3 Zr, T-Al 20 Cu 2 Mn 3 The high temperature stability strengthening phase is formed, thereby significantly improving the high temperature strength of the Al-Cu-Mn aluminum alloy. Since the amount of scandium used in nickel or nickel and scandium as a modifier is relatively small compared with that of scandium alone as a modifier, the economic cost of the copper-aluminum alloy can be greatly reduced. The Al-Cu-Mn-Zr-Ni alloy prepared by the present invention has a simple preparation process, easy operation, and low cost, and has a wide application prospect in the application field of structural components of aerospace.

[0065] 2. The Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy prepared by the method of the present invention has instantaneous tensile properties after heat exposure at 300°C for 30 minutes: yield strength greater than 150MPa, tensile strength greater than 200MPa, and elongation not less than 6%; the instantaneous tensile properties after heat exposure at 350°C for 30 minutes are: yield strength not less than 130MPa, tensile strength greater than 175MPa, and elongation not less than 4%, which can meet the mechanical property requirements of materials in the aerospace field.

[0066] 3. When nickel is added to strengthen the high temperature strength of the copper-aluminum alloy, the precipitation phase composition in the copper-aluminum alloy structure is regulated by changing and strictly controlling the content of alloy elements such as copper, manganese, zirconium, titanium, nickel, vanadium, cadmium and boron, and improving the heat treatment method of the copper-aluminum alloy ingot. With the help of Ni alloying, more Al-Cu-Ni phases with high heat resistance are formed in the alloy, thereby improving the high temperature strength of the alloy grain boundary; secondly, the preparation method of the present invention can make the main strengthening phase γ-Al formed after Ni alloying 7 Cu 4 Ni promotes θ'-Al 2 The precipitation of Cu phase and the inhibition of θ'-Al 2 The coarsening rate of Cu phase under high temperature conditions increases the θ'-Al 2 The thermal stability of the Cu phase under high temperature conditions reduces the θ'-Al phase that is semi-coherent with the matrix. 2 θ-Al where Cu forms a coherent relationship with the matrix 2 The transformation rate of the Cu phase is increased, thereby greatly improving the high-temperature mechanical properties of the copper-aluminum alloy. The Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy prepared by the present invention has higher mechanical properties and high-temperature stability compared with other commercial 2 series cast Al-Cu series alloys.

[0067] 4. When nickel and scandium are added to strengthen the high temperature strength of copper-aluminum alloy at the same time, the dosage of alloy elements such as copper, manganese, zirconium, titanium, nickel, scandium, vanadium, cadmium and boron is reasonably designed, and the alloy raw materials are prepared, alloy smelting, alloy casting, and alloy heat treatment (homogenization treatment, solution treatment and aging treatment) are carried out according to the composition design of each alloy element. Through the synergistic effect of alloy composition design and preparation method, a copper-aluminum alloy with small grain size, rich Ni phase, and Al 3 The high-strength heat-resistant aluminum alloy structure in which the high-temperature resistant strengthening phases such as (Sc, Zr) are uniformly dispersed at the grain boundaries further improves the high-temperature resistance of the alloy on the basis of ensuring the mechanical properties of the copper-aluminum alloy, meets the mechanical properties requirements of materials in the aerospace field, and has good economy and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 Microscopic photograph of the metallographic structure near the tensile end of the copper-aluminum alloy prepared in Example 4 of the present invention after heat exposure at 300° C. for 30 minutes. DETAILED DESCRIPTION

[0069] 1. Preparation of Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy by adding nickel

[0070] Example 1

[0071] The preparation method of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy in this embodiment is as follows:

[0072] Step (1), preparing alloy raw materials according to the content of each metal element in the designed Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy;

[0073] In this embodiment, the alloy raw materials are pure aluminum ingots, pure cadmium and master alloy raw materials; the master alloy raw materials are aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-titanium master alloys, aluminum-vanadium master alloys, aluminum-titanium-boron master alloys, aluminum-zirconium master alloys and aluminum-nickel master alloys; the purity of the pure aluminum ingot is greater than or equal to 99.9wt%, and the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper master alloy is Al-50Cu alloy, the aluminum-manganese master alloy is Al-10Mn alloy, the aluminum-titanium master alloy is Al-5Ti alloy, the aluminum-vanadium master alloy is Al-5V alloy, the aluminum-titanium-boron master alloy is Al-5Ti-B alloy, the aluminum-zirconium master alloy is Al-5Zr alloy, and the aluminum-nickel master alloy is Al-10Ni alloy; the impurity content in the master alloy raw materials is less than or equal to 0.1wt%;

[0074] Step (2), placing the alloy raw material in a muffle furnace, heating it to 200° C. and performing insulation treatment for 2 hours; placing the alloy raw material after insulation treatment in a preheated melting crucible (the melting crucible surface is sprayed with BN spray, and placed in a medium frequency furnace for preheating in advance, the preheating temperature is 450° C., and the preheating time is 2 hours) for melting, and the melting temperature is 740° C.; the melting order of the alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, wait until one alloy raw material is fully melted before adding the next alloy raw material;

[0075] After all the alloy raw materials are melted, stir them thoroughly and remove the slag, then add the C wrapped in aluminum foil. 6 Cl 6The refining agent powder is refined for 10 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection during the refining process; after the refining is completed, the temperature is kept at 730°C for 20 minutes, and after the heat preservation, the refining first slag removal treatment, stirring and refining second slag removal treatment are carried out in sequence, and the alloy liquid is obtained after the second slag removal treatment after refining;

[0076] Step (3), casting the alloy liquid into a preheated metal mold to obtain an aluminum alloy ingot; the casting temperature of the alloy liquid is 710° C., and the casting time is controlled within 15 seconds; the preheating temperature of the metal mold is 200° C., and boron nitride is sprayed inside the metal mold cavity as a release agent;

[0077] Step (4), subjecting the aluminum alloy ingot to secondary heat treatment. After the secondary heat treatment, an Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy can be obtained. The specific method of the secondary heat treatment is:

[0078] Step (4-1) first stage heat treatment: the aluminum alloy ingot is heated to 400°C at a rate of 5°C / min and kept at 400°C for 8h, then heated to 550°C at a rate of 5°C / min and kept at 550°C for 4h; then the aluminum alloy ingot is transferred to 80°C water for water quenching for 5s, and then naturally cooled to room temperature;

[0079] Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 190°C at a rate of 5°C / min, kept at 190°C for 4 hours, and then naturally cooled to room temperature.

[0080] The Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy prepared in this embodiment is composed of the following components in mass fraction: 4.9wt% copper, 0.2wt% manganese, 0.15wt% zirconium, 0.2wt% nickel, 0.15wt% titanium, 0.1wt% vanadium, 0.015wt% cadmium, 0.003wt% boron, the iron content is less than or equal to 0.1wt%, the silicon content is less than or equal to 0.05wt%, the magnesium content is less than or equal to 0.05wt%, and the balance is aluminum.

[0081] Example 2

[0082] The preparation method of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy in this embodiment is different from that in Embodiment 1 only in that, in step (4), the specific method of the secondary heat treatment is:

[0083] Step (4-1) first stage heat treatment: heating the aluminum alloy ingot to 450°C at a rate of 10°C / min, and keeping it at 450°C for 4 hours, then heating it to 500°C at a rate of 5°C / min, and keeping it at 500°C for 6 hours; then transferring the aluminum alloy ingot to 80°C water for water quenching for 5 seconds, and then naturally cooling it to room temperature;

[0084] Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 140°C at a rate of 5°C / min, kept at 140°C for 5 hours, and then naturally cooled to room temperature.

[0085] The Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy prepared in this embodiment is composed of the following components in mass fraction: 5.2wt% copper, 0.3wt% manganese, 0.18wt% zirconium, 0.3wt% nickel, 0.16wt% titanium, 0.2wt% vanadium, 0.02wt% cadmium, 0.003wt% boron, the iron content is less than or equal to 0.1wt%, the silicon content is less than or equal to 0.05wt%, the magnesium content is less than or equal to 0.05wt%, and the balance is aluminum.

[0086] Example 3

[0087] The preparation method of the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy in this embodiment is different from that in Embodiment 1 only in that, in step (4), the specific method of the secondary heat treatment is:

[0088] Step (4-1) first stage heat treatment: heating the aluminum alloy ingot to 350°C at a rate of 5°C / min, and keeping it at 350°C for 8h, then heating it to 500°C at a rate of 10°C / min, and keeping it at 500°C for 8h; then transferring the aluminum alloy ingot to 60°C water for water quenching for 5s, and then naturally cooling it to room temperature;

[0089] Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 130°C at a rate of 5°C / min, kept at 130°C for 8h, and then naturally cooled to room temperature.

[0090] The Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy prepared in this embodiment is composed of the following components in mass fraction: 5.1wt% copper, 0.4wt% manganese, 0.15wt% zirconium, 0.5wt% nickel, 0.15wt% titanium, 0.15wt% vanadium, 0.03wt% cadmium, 0.0025wt% boron, the iron content is less than or equal to 0.1wt%, the silicon content is less than or equal to 0.05wt%, the magnesium content is less than or equal to 0.05wt%, and the balance is aluminum.

[0091] Comparative Example 1

[0092] The copper-aluminum alloy prepared in this comparative example is 2618 aluminum alloy, and its preparation method is different from that of Example 1 only in that, in step (4), the heat treatment method is as follows: the aluminum alloy ingot is subjected to double-stage homogenization at 475°C / 5h+510°C / 24h, hot-rolled into a thin plate, and then solution-treated at 510°C for 6h and quenched, and then artificially aged at 185°C to a peak aging state to obtain a 2618 aluminum alloy plate; in step (1), the prepared alloy raw materials are adjusted accordingly according to the designed alloying elements.

[0093] In this comparative example, the 2618 aluminum alloy is composed of the following components in mass fractions: 2.3wt% copper, 1.6wt% magnesium, 1.1wt% iron, 1.0wt% nickel, and the balance is aluminum.

[0094] The copper-aluminum alloys prepared in Examples 1 to 3 and Comparative Example 1 were tested for mechanical properties respectively, and the testing method was as follows: the room temperature mechanical properties test was completed using an electronic universal material testing machine, the equipment used was a WDW-100M universal tensile machine, and the tensile rate was 0.5 mm / min; the high temperature mechanical properties test was completed using a WSW-100G testing machine, and the tensile rate was 1 mm / min. The room temperature and high temperature tensile tests refer to GB / T228.1-2010 "Tensile Test of Metal Materials". The test results are shown in Table 1.

[0095] Table 1 Mechanical properties test results of different copper-aluminum alloys

[0096]

[0097] In Table 1, σ (MPa) indicates tensile strength, and δ (%) indicates elongation.

[0098] By comparing the test results in Table 1, it can be found that the high-temperature mechanical properties, including tensile strength and elongation, of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloys prepared in Examples 1 to 3 are better than those of the existing aluminum alloy after T6 heat treatment (Comparative Example 1) at room temperature and high temperature conditions, and can meet the requirements of casting aluminum alloys under high temperature conditions.

[0099] The present invention controls the addition ratio of each metal element, adopts appropriate preparation process and conditions, improves the heat treatment process and parameters, so that the regulating effect of Ni element on the heat resistance of copper-aluminum alloy is fully exerted (most of the nickel elements in copper-aluminum alloy exist in the form of Al-Cu-Ni phase with high temperature resistance), thereby improving the high temperature performance of copper-aluminum alloy; at the same time, the preparation method of the present invention can also fully exert the synergistic effect between Zr, Ti and B, thereby maintaining the copper-aluminum alloy with ideal room temperature performance. It can be seen from the above embodiments that the room temperature tensile strength of the prepared copper-aluminum alloy can reach 487MPa, and after 300℃ heat exposure for 0.5h, the high temperature instantaneous tensile strength of the copper-aluminum alloy can reach 328MPa, and after 350℃ heat exposure for 0.5h, the high temperature instantaneous tensile strength of the copper-aluminum alloy reaches 213MPa.

[0100] 2. Example 4 of preparing Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy by adding nickel and scandium simultaneously

[0101] The preparation method of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy in this embodiment is as follows:

[0102] Step (1), preparing alloy raw materials according to the content of each metal element in the designed Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy;

[0103] In this embodiment, the alloy raw materials are pure aluminum ingots, pure cadmium and master alloy raw materials; the master alloy raw materials are aluminum-copper master alloys, aluminum-manganese master alloys, aluminum-titanium master alloys, aluminum-vanadium master alloys, aluminum-titanium-boron master alloys, aluminum-zirconium master alloys, aluminum-nickel master alloys and aluminum-scandium master alloys; the purity of the pure aluminum ingot is greater than or equal to 99.9wt%, and the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper master alloy is Al-50Cu alloy, the aluminum-manganese master alloy is Al-10Mn alloy, the aluminum-titanium master alloy is Al-5Ti alloy, the aluminum-vanadium master alloy is Al-5V alloy, the aluminum-titanium-boron master alloy is Al-5Ti-B alloy, the aluminum-zirconium master alloy is Al-5Zr alloy, the aluminum-nickel master alloy is Al-10Ni alloy, and the aluminum-scandium master alloy is Al-2Sc alloy; the impurity content in the master alloy raw materials is less than or equal to 0.1wt%;

[0104] Step (2), placing the alloy raw material in a muffle furnace, heating it to 300° C. and performing insulation treatment for 2 hours; placing the alloy raw material after insulation treatment in a preheated melting crucible (the melting crucible surface is sprayed with BN spray, and placed in a medium frequency furnace for preheating in advance, the preheating temperature is 500° C., and the preheating time is 2 hours) for melting, and the melting temperature is 720° C.; the melting order of the alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, aluminum-scandium master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, wait until one alloy raw material is fully melted before adding the next alloy raw material;

[0105] After all the alloy raw materials are melted, stir them thoroughly and remove the slag, then add the C wrapped in aluminum foil. 6 Cl 6 The refining agent powder is refined for 20 minutes, and high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection during the refining process; after the refining is completed, the temperature is kept at 720°C for 30 minutes, and after the heat preservation, the refining first slag removal treatment, stirring and refining second slag removal treatment are sequentially performed, and the alloy liquid is obtained after the second slag removal treatment after refining;

[0106] Step (3), casting the alloy liquid into a preheated metal mold to obtain an aluminum alloy ingot; the casting temperature of the alloy liquid is 710°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent;

[0107] Step (4), heat treating the aluminum alloy ingot. After the heat treatment, an Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy can be obtained. The heat treatment comprises the following steps:

[0108] Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 350° C. at a rate of 5° C. / min, and keeping the temperature at 350° C. for 3 h;

[0109] Step (4-2) solution treatment: heating the aluminum alloy ingot after homogenization treatment to 520°C at a rate of 5°C / min, and keeping it at 520°C for 8h, and then performing water quenching treatment, the water quenching treatment temperature is 70°C, and the water quenching treatment time is equal to 5s; and then naturally cooling to room temperature;

[0110] Step (4-3) Aging treatment: The aluminum alloy ingot after the solution treatment is heated to 160°C at a rate of 5°C / min, and kept at 160°C for 8 hours; then naturally cooled to room temperature.

[0111] The contents of the components of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy prepared in this embodiment are as follows: 5.4wt% copper, 0.4wt% manganese, 0.1wt% zirconium, 0.3wt% nickel, 0.1wt% scandium, 0.3wt% titanium, 0.2wt% vanadium, 0.15wt% cadmium, 0.04wt% boron, the content of iron is less than or equal to 0.10wt%, the content of silicon is less than or equal to 0.05wt%, the content of magnesium is less than or equal to 0.05wt%, and the balance is aluminum.

[0112] Example 5

[0113] The preparation method of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy in this embodiment is different from that in Embodiment 4 only in that, in step (4), the specific method of heat treatment is:

[0114] Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 400° C. at a rate of 5° C. / min, and keeping the temperature at 400° C. for 2.5 h;

[0115] Step (4-2) solution treatment: heating the aluminum alloy ingot after homogenization treatment to 530°C at a rate of 10°C / min, and keeping it at 530°C for 8h, and then performing water quenching treatment, the water quenching treatment temperature is 60°C, and the water quenching treatment time is equal to 5s; and then naturally cooling to room temperature;

[0116] Step (4-3) Aging treatment: The aluminum alloy ingot after the solution treatment is heated to 170°C at a rate of 5°C / min, and kept at 170°C for 10 hours; then naturally cooled to room temperature.

[0117] The contents of the components of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy prepared in this embodiment are as follows: 5.5wt% copper, 0.4wt% manganese, 0.1wt% zirconium, 0.3wt% nickel, 0.05wt% scandium, 0.3wt% titanium, 0.2wt% vanadium, 0.15wt% cadmium, 0.04wt% boron, the content of iron is less than or equal to 0.10wt%, the content of silicon is less than or equal to 0.05wt%, the content of magnesium is less than or equal to 0.05wt%, and the balance is aluminum.

[0118] Example 6

[0119] The preparation method of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy in this embodiment is different from that in Embodiment 4 only in that, in step (4), the specific method of heat treatment is:

[0120] Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 450° C. at a rate of 10° C. / min, keeping the temperature at 450° C. for 2 h, and then naturally cooling to room temperature;

[0121] Step (4-2) solution treatment: heating the aluminum alloy ingot after homogenization treatment to 540°C at a rate of 10°C / min, and keeping it at 540°C for 8h, and then performing water quenching treatment, the water quenching treatment temperature is 80°C, and the water quenching treatment time is equal to 5s; and then naturally cooling to room temperature;

[0122] Step (4-3) Aging treatment: The aluminum alloy ingot after the solution treatment is heated to 180°C at a rate of 10°C / min, and kept at 180°C for 8 hours; then naturally cooled to room temperature.

[0123] The contents of the components of the Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy prepared in this embodiment are as follows: 5.6wt% copper, 0.4wt% manganese, 0.1wt% zirconium, 0.3wt% nickel, 0.15wt% scandium, 0.3wt% titanium, 0.2wt% vanadium, 0.15wt% cadmium, 0.04wt% boron, the content of iron is less than or equal to 0.10wt%, the content of silicon is less than or equal to 0.05wt%, the content of magnesium is less than or equal to 0.05wt%, and the balance is aluminum.

[0124] Comparative Example 2

[0125] The high-strength heat-resistant cast aluminum alloy in this comparative example is composed of the following components in mass fraction: 5.4wt% copper, 0.4wt% manganese, 0.3wt% nickel, 0.3wt% titanium, 0.1wt% scandium, 0.1wt% zirconium, 0.2wt% vanadium, 0.04wt% boron, the iron content is less than or equal to 0.15wt%, the silicon content is less than or equal to 0.15wt%, the magnesium content is less than or equal to 0.15wt%, and the balance is aluminum.

[0126] The preparation process thereof is different from that of Example 4 only in that the heat treatment in step (4) adopts the T6 heat treatment process; and in step (1), the prepared alloy raw material is adjusted accordingly according to the designed alloy elements.

[0127] The copper-aluminum alloys prepared in Examples 4 to 6 and Comparative Example 2 were tested for mechanical properties, respectively, and the testing method was as follows: processing into standard tensile specimens according to the national standard GB6397-86 "Metal Tensile Test Specimens"; stretching was performed on a Shimadzu AG-I250kN electronic tensile testing machine at a stretching rate of 1mm / min; when stretching at high temperature, the alloys were kept warm for 30 minutes before stretching. The test results are shown in Table 2.

[0128] Table 2 Mechanical properties test results of different copper-aluminum alloys

[0129]

[0130] In Table 2, UTS represents tensile strength, in MPa; YS represents yield strength, in MPa; δ represents elongation, in %.

[0131] It can be found from Table 2 that the high-temperature mechanical properties (tensile strength, yield strength and elongation) of the high-strength heat-resistant cast aluminum alloys prepared in Examples 4 to 6 are better than those of the high-temperature resistant aluminum alloy in Comparative Example 2 after the existing T6 heat treatment under high temperature conditions, and can meet the requirements of casting aluminum alloys under high temperature conditions.

[0132] The Al-Cu-Mn-Zr-Ni-Sc high-strength heat-resistant cast aluminum alloy prepared by the method of the present invention has a uniform microstructure (attached Figure 1 ), high tensile strength and excellent plasticity, and the preparation method of copper-aluminum alloy is simple, low-cost and highly practical.

[0133] When nickel and scandium are added to strengthen the copper-aluminum alloy, based on the synergistic effect between the various element components and the preparation process, the high-temperature strength of the alloy is greatly improved while ensuring the room temperature mechanical strength of the alloy material; the solid solubility of Ni in Al is relatively low. The present invention controls the Ni content in the aluminum alloy, adopts improved preparation process parameters, and strictly controls its heat treatment conditions, so that a trace amount of Ni can react with Al and Cu atoms in the alloy to generate a large number of dispersedly distributed network and semi-network high-temperature resistant phases Al7Cu4Ni at the grain boundaries, thereby improving the high-temperature resistance of the alloy; at the same time, it can also allow a trace amount of Sc to interact with the Zr element in the alloy to form a high-temperature resistant core-shell structure strengthening phase Al 3 (Sc, Zr), thereby significantly improving the room temperature and high temperature mechanical properties of the alloy, and a part of the Sc element can be segregated in the Al 2 On the Cu phase surface, under high temperature conditions, the segregation of Sc greatly reduces the Al 2 The coarsening rate of Cu phase slows down the Al 2 The transformation rate of the metastable phase of the Cu phase to the stable phase further improves the room temperature and high temperature mechanical properties of the alloy.

[0134] The Al-Cu-Mn-Zr-Ni-Sc high-strength cast heat-resistant aluminum alloy prepared by the method of the present invention has good room temperature mechanical properties and high temperature heat resistance. The tensile strength at room temperature reaches more than 492 MPa, the instantaneous tensile strength after 300°C high temperature heat exposure for 30 minutes reaches more than 264 MPa, and the instantaneous tensile strength after 350°C heat exposure for 30 minutes reaches more than 210 MPa, which can meet the mechanical properties of materials in the aerospace field. In addition, compared with the deformed aluminum alloy, the alloy has a simple preparation process, low requirements on preparation equipment, and is easy to operate. At the same time, the prepared alloy has good mechanical properties, can replace the deformed aluminum alloy in the aerospace field materials to a certain extent, and can effectively reduce the preparation cost of the alloy.

[0135] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. An Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, characterized in that: The invention is composed of the following components in mass fractions: 1.0-9.0wt% copper, 0.1-1.0wt% manganese, 0.01-0.5wt% zirconium, 0.1-1.5wt% nickel, 0-0.45wt% scandium, 0.1-0.6wt% titanium, 0.01-0.45wt% vanadium, 0.01-0.4wt% cadmium, 0.001-0.08wt% boron, the content of iron is less than or equal to 0.15wt%, the content of silicon is less than or equal to 0.15wt%, the content of magnesium is less than or equal to 0.15wt%, and the balance is aluminum.

2. A method for preparing an Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy, characterized in that: The steps include: Step (1), preparing alloy raw materials according to the content of each metal element in the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy as claimed in claim 1; Step (2), heating the alloy raw material and performing heat preservation treatment; The alloy raw material after the heat preservation treatment is placed in a preheated melting furnace for melting to obtain alloy liquid; Step (3), casting the alloy liquid into a preheated metal mold to obtain an aluminum alloy ingot; Step (4), heat treating the aluminum alloy ingot. After the heat treatment, the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy as claimed in claim 1 can be obtained.

3. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 2, characterized in that: In step (1), the components of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy are prepared as alloy raw materials according to the following contents: copper 4.6-5.4wt%, manganese 0.1-0.5wt%, zirconium 0.1-0.4wt%, nickel 0.1-0.5wt%, titanium 0.1-0.4wt%, vanadium 0.1-0.3wt%, cadmium 0.01-0.03wt%, boron 0.001-0.003wt%, iron content less than or equal to 0.15wt%, silicon content less than or equal to 0.15wt%, magnesium content less than or equal to 0.15wt%, and the balance is aluminum; The alloy raw materials are pure aluminum ingots, pure cadmium and intermediate alloy raw materials; the intermediate alloy raw materials are aluminum-copper intermediate alloys, aluminum-manganese intermediate alloys, aluminum-titanium intermediate alloys, aluminum-vanadium intermediate alloys, aluminum-titanium-boron intermediate alloys, aluminum-zirconium intermediate alloys and aluminum-nickel intermediate alloys; the purity of the pure aluminum ingots is greater than or equal to 99.7wt%, and the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper intermediate alloy is Al-50Cu alloy, the aluminum-manganese intermediate alloy is Al-10Mn alloy, the aluminum-titanium intermediate alloy is Al-5Ti alloy, the aluminum-vanadium intermediate alloy is Al-5V alloy, the aluminum-titanium-boron intermediate alloy is Al-5Ti-B alloy, the aluminum-zirconium intermediate alloy is Al-5Zr alloy, and the aluminum-nickel intermediate alloy is Al-10Ni alloy; and the impurity content in the intermediate alloy raw materials is less than or equal to 0.1wt%.

4. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 3, characterized in that: In step (4), the heat treatment comprises the following steps: Step (4-1) first stage heat treatment: heating the aluminum alloy ingot to 350-450°C at a rate of 5-10°C / min, and keeping it at 350-450°C for 4-8h, then heating it to 500-550°C at a rate of 5-10°C / min, and keeping it at 500-550°C for 4-8h; then transferring the aluminum alloy ingot to water at 50-80°C for water quenching for 1-10s, and then naturally cooling it to room temperature; Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 130-190°C at a rate of 5-10°C / min, kept at 130-190°C for 4-8h, and then naturally cooled to room temperature.

5. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 3, characterized in that: In step (2), the conditions for heat preservation of the alloy raw material are: heat preservation at 200-300°C for 2-3h; preheating temperature of the smelting furnace is 450-500°C, and the preheating time is 2-3h; smelting temperature is 600-740°C; The melting order of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, one alloy raw material is fully melted before adding the next alloy raw material; After all the alloy raw materials are melted, they are fully stirred and slag-stripped, and then C6Cl6 refining agent powder wrapped in aluminum foil is added and refined for 10 to 40 minutes. During the refining process, high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection; after the refining is completed, the temperature is kept at 700 to 760° C. for 20 to 30 minutes, and after the insulation is completed, the refining is subjected to a first slag-stripping treatment, stirring, and a second slag-stripping treatment after refining are sequentially performed, and the alloy liquid is obtained after the second slag-stripping treatment after refining is completed; In step (3), the casting temperature of the alloy liquid is 710°C to 740°C, and the casting time is controlled within 20 seconds; the metal mold preheating temperature is 100 to 300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent.

6. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to any one of claims 3 to 5, characterized in that: In step (1), an alloy raw material is prepared according to the following contents of each component of an Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy: 5.1wt% copper, 0.4wt% manganese, 0.15wt% zirconium, 0.5wt% nickel, 0.15wt% titanium, 0.15wt% vanadium, 0.03wt% cadmium, 0.0025wt% boron, the content of iron is less than or equal to 0.1wt%, the content of silicon is less than or equal to 0.05wt%, the content of magnesium is less than or equal to 0.05wt%, and the balance is aluminum; In step (2), the conditions for heat preservation of the alloy raw material are: heat preservation at 200°C for 2 hours; preheating temperature of the smelting furnace is 450°C, and the preheating time is 2 hours; smelting temperature is 740°C; The melting order of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, pure cadmium and aluminum-titanium-boron master alloy; during melting, one alloy raw material is fully melted before adding the next alloy raw material; After all the alloy raw materials are melted, they are fully stirred and slag-stripped, and then C6Cl6 refining agent powder wrapped in aluminum foil is added and refined for 10 minutes. During the refining process, high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection; after the refining is completed, the temperature is kept at 730°C for 20 minutes, and after the insulation is completed, the refining is subjected to a first slag-stripping treatment, stirring, and a second slag-stripping treatment after refining are sequentially performed, and the alloy liquid is obtained after the second slag-stripping treatment after refining is completed; In step (3), the casting temperature of the alloy liquid is 710°C, and the casting time is controlled within 15 seconds; the preheating temperature of the metal mold is 200°C, and boron nitride is sprayed inside the metal mold cavity as a release agent; In step (4), the heat treatment comprises the following steps: Step (4-1) first stage heat treatment: the aluminum alloy ingot is heated to 350°C at a rate of 5°C / min and kept at 350°C for 8h, then heated to 500°C at a rate of 10°C / min and kept at 500°C for 4h; Then the aluminum alloy ingot was transferred to water at 60°C for water quenching for 5 seconds, and then naturally cooled to room temperature; Step (4-2) Second stage heat treatment: The aluminum alloy ingot after water quenching is heated to 130°C at a rate of 5°C / min, kept at 130°C for 4 hours, and then naturally cooled to room temperature.

7. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 2, characterized in that: In step (1), the components of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy are prepared as alloy raw materials according to the following contents: copper 1.0-9.0wt%, manganese 0.1-1.0wt%, zirconium 0.01-0.5wt%, nickel 0.1-1.5wt%, scandium 0.05-0.45wt%, titanium 0.1-0.6wt%, vanadium 0.01-0.45wt%, cadmium 0.1-0.4wt%, boron 0.005-0.08wt%, iron content less than or equal to 0.15wt%, silicon content less than or equal to 0.15wt%, magnesium content less than or equal to 0.15wt%, and the balance is aluminum; The alloy raw materials are pure aluminum ingots, pure cadmium and intermediate alloy raw materials; the intermediate alloy raw materials are aluminum-copper intermediate alloys, aluminum-manganese intermediate alloys, aluminum-titanium intermediate alloys, aluminum-vanadium intermediate alloys, aluminum-titanium-boron intermediate alloys, aluminum-zirconium intermediate alloys, aluminum-nickel intermediate alloys and aluminum-scandium intermediate alloys; the purity of the pure aluminum ingots is greater than or equal to 99.7wt%, and the purity of the pure cadmium is greater than or equal to 99.9wt%; the aluminum-copper intermediate alloy is Al-50Cu alloy, the aluminum-manganese intermediate alloy is Al-10Mn alloy, the aluminum-titanium intermediate alloy is Al-5Ti alloy, the aluminum-vanadium intermediate alloy is Al-5V alloy, the aluminum-titanium-boron intermediate alloy is Al-5Ti-B alloy, the aluminum-zirconium intermediate alloy is Al-5Zr alloy, the aluminum-nickel intermediate alloy is Al-10Ni alloy, and the aluminum-scandium intermediate alloy is Al-2Sc alloy; and the impurity content in the intermediate alloy raw materials is less than or equal to 0.1wt%.

8. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 7, characterized in that: In step (4), the heat treatment comprises the following steps: Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 350-450° C. at a rate of 5-10° C. / min, and keeping the temperature at 350-450° C. for 2-3 hours; Step (4-2) solution treatment: the aluminum alloy ingot after homogenization treatment is immediately heated to 520-540°C at a rate of 5-10°C / min, and kept at 520-540°C for 8-10h, and then water quenched at a temperature of 60-80°C for a time of less than or equal to 10s; and then naturally cooled to room temperature; Step (4-3) aging treatment: the aluminum alloy ingot after solution treatment is heated to 160-180°C at a rate of 5-10°C / min, and kept at 160-180°C for 8-10 hours; then naturally cooled to room temperature.

9. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to claim 7, characterized in that: In step (2), the conditions for heat preservation of the alloy raw materials are: heat preservation at 200-300°C for 2-3h; the preheating temperature of the smelting furnace is 450-500°C, and the preheating time is 2-3h; the smelting order of the alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, aluminum-scandium master alloy, pure cadmium and aluminum-titanium-boron master alloy; the smelting temperature is 600-740°C. During smelting, after one alloy raw material is fully melted, Then add the next alloy raw material; after all the alloy raw materials are melted, stir them fully and perform slag removal treatment, then add C6Cl6 refining agent powder wrapped in aluminum foil and refine for 10 to 40 minutes, and during the refining process, introduce high-purity argon gas with a concentration greater than or equal to 99.9% for protection; after the refining is completed, keep the temperature at 700 to 760° C. for 20 to 30 minutes, and after the insulation is completed, perform a first slag removal treatment after refining, stirring, and a second slag removal treatment after refining in sequence, and after the second slag removal treatment after refining is completed, an alloy liquid is obtained; In step (3), the casting temperature of the alloy liquid is 710-740°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 100-300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent.

10. The method for preparing the Al-Cu-Mn-Zr-Ni series high-strength heat-resistant cast aluminum alloy according to any one of claims 7 to 9, characterized in that: In step (1), an alloy raw material is prepared according to the following contents of each component of the Al-Cu-Mn-Zr-Ni high-strength heat-resistant cast aluminum alloy: 5.4wt% copper, 0.4wt% manganese, 0.1wt% zirconium, 0.3wt% nickel, 0.1wt% scandium, 0.3wt% titanium, 0.2wt% vanadium, 0.15wt% cadmium, 0.04wt% boron, the content of iron is less than or equal to 0.10wt%, the content of silicon is less than or equal to 0.05wt%, the content of magnesium is less than or equal to 0.05wt%, and the balance is aluminum; In step (2), the conditions for heat preservation of the alloy raw material are: heat preservation at 300°C for 2h; preheating temperature of the smelting furnace is 500°C, and the preheating time is 2h; smelting temperature is 720°C; The smelting order of alloy raw materials is: pure aluminum ingot, aluminum-copper master alloy, aluminum-zirconium master alloy, aluminum-titanium master alloy, aluminum-manganese master alloy, aluminum-vanadium master alloy, aluminum-nickel master alloy, aluminum-scandium master alloy, pure cadmium and aluminum-titanium-boron master alloy; during smelting, one alloy raw material is fully melted before adding the next alloy raw material; After all the alloy raw materials are melted, they are fully stirred and slag-stripped, and then C6Cl6 refining agent powder wrapped in aluminum foil is added and refined for 20 minutes. During the refining process, high-purity argon gas with a concentration greater than or equal to 99.9% is introduced for protection; after the refining is completed, the temperature is kept at 720°C for 30 minutes, and after the insulation is completed, the refining is subjected to a first slag-stripping treatment, stirring, and a second slag-stripping treatment after refining are sequentially performed, and the alloy liquid is obtained after the second slag-stripping treatment after refining is completed; In step (3), the casting temperature of the alloy liquid is 710°C, and the casting time is controlled within 20 seconds; the preheating temperature of the metal mold is 300°C, and boron nitride is sprayed inside the metal mold cavity as a release agent; In step (4), the heat treatment comprises the following steps: Step (4-1) homogenization treatment: heating the aluminum alloy ingot to 350° C. at a rate of 5° C. / min and keeping the temperature at 350° C. for 2 h; Step (4-2) solution treatment: heating the aluminum alloy ingot after homogenization treatment to 520°C at a rate of 5°C / min, and keeping it at 520°C for 8h, and then performing water quenching treatment, the water quenching treatment temperature is 70°C, and the water quenching treatment time is equal to 5s; and then naturally cooling to room temperature; Step (4-3) Aging treatment: The aluminum alloy ingot after the solution treatment is heated to 160°C at a rate of 5°C / min, and kept at 160°C for 8 hours; then naturally cooled to room temperature.

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