High-temperature-resistant high-strength aluminum alloy material and preparation method thereof

Abstract

The present application relates to the technical field of aluminum alloy material, in particular to a high-temperature-resistant and high-strength aluminum alloy material and a preparation method thereof.The present application overcomes the problems of insufficient mechanical properties and poor high-temperature resistance of the existing aluminum alloy material.By introducing multiple synergistic strengthening elements, including copper, magnesium, scandium, zirconium, nickel, manganese and titanium, into the aluminum alloy matrix, and adding multiple layers of graphene nanosheets through step-by-step melting, under the protection of argon, the present application refines the grains through hexachloroethane refining and lithium salt complexing agent, and prepares a fusion alloy;combined with multi-stage fine melting, multi-stage heat treatment process, three-stage aging treatment and surface modification process, the microstructure is optimized and the surface performance is improved.The prepared aluminum alloy material significantly improves the mechanical properties, high-temperature resistance and surface oxidation resistance of the aluminum alloy through multi-element synergy and multi-process optimization, and is suitable for the field of aerospace.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy materials, in particular to a high-temperature-resistant high-strength aluminum alloy material and a preparation method thereof. BACKGROUND

[0002] At present, as an important structural material, aluminum alloy is widely used in the fields of aerospace, automobile, electronics, etc. due to its low density, high specific strength, good thermal and electrical conductivity, corrosion resistance, etc. However, with the increasing requirements of modern industry on material performance, especially in high-temperature service environments such as engines, high-speed trains, and spacecraft, traditional aluminum alloys generally face the bottleneck problems of insufficient mechanical properties, especially high-temperature mechanical properties, and poor high-temperature resistance.

[0003] On the one hand, although traditional high-strength aluminum alloys have certain strength at room temperature, their strength and hardness will decrease sharply at high temperatures due to factors such as grain boundary softening, precipitate coarsening, and intensified dislocation movement, resulting in insufficient material carrying capacity and limiting their application in high-temperature structural parts. At the same time, for some application scenarios with extremely high requirements for strength and hardness, the strength of existing aluminum alloys still cannot fully meet the requirements.

[0004] On the other hand, traditional aluminum alloys are prone to high-temperature creep, oxidation corrosion, and thermal fatigue failure modes during long-term service at high temperatures. High-temperature creep leads to irreversible plastic deformation of the material under constant load and high temperature, seriously affecting the dimensional stability and service life of the parts. High-temperature oxidation and wear will accelerate the surface failure of the material and reduce its protective ability.

[0005] In the prior art, the introduction of multiple elements forms a stable mechanical improvement effect, but the overall performance change under high-temperature conditions cannot be maintained. With the increasing demand for high-temperature resistance, how to effectively improve the high-temperature resistance of aluminum alloy while maintaining the mechanical properties is a key challenge faced by current high-performance aluminum alloy research.

[0006] Therefore, a high-temperature-resistant high-strength aluminum alloy material and a preparation method thereof are proposed. SUMMARY

[0007] The application aims to provide a high-temperature-resistant high-strength aluminum alloy material and a preparation method thereof. The application introduces multiple synergistically acting strengthening elements, including copper, magnesium, scandium, zirconium, nickel, manganese and titanium, into an aluminum alloy matrix, simultaneously adds multiple layers of graphene nanosheets, step-by-step smelts, under argon protection, refines grains through hexachloroethane refining and lithium salt complexing agent, and prepares a fusion alloy; then combines multi-stage refined smelting, a phased heat treatment process, three-stage aging treatment and a surface modification process, optimizes the microstructure and improves the surface performance. The prepared aluminum alloy material significantly improves the mechanical properties, high-temperature resistance and surface oxidation resistance of the aluminum alloy through multi-element synergy and multi-process optimization, and is suitable for the aerospace field.

[0008] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0009] The application provides a preparation method of a high-temperature-resistant high-strength aluminum alloy material, including the following steps.

[0010] The aluminum ingot, copper-aluminum intermediate alloy, aluminum-manganese alloy, aluminum-nickel alloy, aluminum-titanium alloy, metallic magnesium, aluminum-scandium alloy, aluminum-zirconium alloy and graphene nanosheets are step-by-step smelted to obtain a fusion alloy.

[0011] The fusion alloy is refined by hexachloroethane refining, and the lithium salt complexing agent is cast to obtain a cast alloy.

[0012] The cast alloy is subjected to a phased heat treatment to obtain a solid solution.

[0013] The solid solution is subjected to three-stage aging treatment to obtain an aluminum alloy precursor; the aluminum alloy precursor is subjected to plasma chemical vapor deposition and naturally cooled to room temperature to obtain a high-temperature-resistant high-strength aluminum alloy material.

[0014] Preferably, the step-by-step smelting includes the following steps.

[0015] In a vacuum induction melting furnace, the aluminum ingot is placed in a graphite crucible under argon protection, heated to 750-800℃ to completely melt, and then the copper-aluminum master alloy is added, the temperature is kept at 720-750℃, the stirring speed is 200r / min, and the stirring time is 10min; then the aluminum-manganese alloy, aluminum-nickel alloy and aluminum-titanium alloy are added, and the mixed solution is obtained by keeping the temperature and stirring for 20min at a speed of 200r / min; the multilayer graphene nanosheet with a mass fraction of 0.3%-0.5% is precisely wrapped with high-purity aluminum foil, and then the mixed solution is obtained by using bell jar pressure into the mixed solution, the stirring speed is 400-500r / min, and the stirring time is 20-30min; the uniform solution is cooled to 700-730℃, the metal magnesium is added, the stirring speed is kept at 200r / min, and the stirring time is 10min; then the aluminum-scandium alloy and the aluminum-zirconium alloy are added, the temperature is kept at 700-720℃, the stirring speed is adjusted to 100r / min, and the alloy is obtained by stirring for 15-20min.

[0016] Preferably, the casting alloy prepared by the present application contains copper element with a mass percentage of 5.2-5.8%, magnesium element with a mass percentage of 0.8-1.2%, scandium element with a mass percentage of 0.2-0.3%, zirconium element with a mass percentage of 0.1-0.2%, nickel element with a mass percentage of 1.5-2.5%, manganese element with a mass percentage of 0.4-0.9%, titanium element with a mass percentage of 0.08-0.15%, and the rest is aluminum element.

[0017] Preferably, the preparation of the casting alloy comprises the following steps:

[0018] The hexachloroethane is added to the alloy, the amount of hexachloroethane is 0.5% of the mass of the alloy, the temperature is controlled at 730-750℃, and the alloy is kept for 10min; argon gas is introduced for refining treatment, the argon gas flow is controlled at 0.2L / min, and the alloy is refined for 15min to obtain a refined alloy; the dry lithium salt composite agent is added to the refined alloy, the mass percentage is 0.05% of the mass of the alloy, the stirring speed is 50-80r / min, and the alloy is stirred for 3-5min; after standing for 10min, the surface scum is removed, the alloy is poured into a metal mold preheated to 250℃, and the casting alloy is obtained by rapid cooling; the lithium salt composite agent is a powder mixed by lithium carbonate and lithium fluoride in a mass ratio of 3:1.

[0019] Preferably, the stage-by-stage heat treatment comprises the following steps:

[0020] The casting alloy is placed in a 480-500℃ vacuum drying oven for homogenization annealing treatment for 24h, and air cooling is performed at a cooling speed less than 5℃ / min to eliminate casting segregation and make the elements uniformly distributed to obtain an annealed aluminum ingot; the annealed aluminum ingot is heated to 440-460℃ for hot working treatment for 2h to obtain a processed material; the processed material is heated to 510-540℃ for solid solution treatment for 2h, and then rapidly water quenched with a quenching time less than 5s to obtain a solid solution.

[0021] Preferably, the three-stage aging treatment comprises the following steps:

[0022] The solid solution is subjected to the three-stage aging treatment under the protection of nitrogen, the first stage temperature is 110-120 DEG C, the holding time is 4-6h, the cooling rate is maintained at 5-10 DEG C / min; the second stage temperature is 180-190 DEG C, the holding time is 6-8h, the cooling rate is maintained at 5-10 DEG C / min; the third stage temperature is 200-210 DEG C, the holding time is 2-4h, the cooling temperature is maintained at 3-5 DEG C / min to obtain the aluminum alloy precursor.

[0023] Preferably, the plasma chemical vapor deposition comprises the following steps:

[0024] The aluminum alloy precursor is added into the PECVD vacuum chamber, the tubular furnace is vacuumized to 5Pa, argon is continuously introduced into the furnace cavity at 20-30mL / min, the working power is maintained at 300-500W, and ion bombardment is carried out for 15-20min to obtain the treated aluminum alloy; the mixed gas of acetylene and argon is introduced into the treated aluminum alloy, the volume ratio of acetylene to argon is 1:5, the flow rate is maintained at 50-60mL / min, the carbon layer is deposited, the vacuum degree is maintained at 10-20Pa, the deposition temperature is 160-200 DEG C, the deposition time is 2-3h, and the vacuum condition is maintained, and the aluminum alloy material is obtained by naturally cooling to room temperature; wherein the thickness of the plating layer is 2-3mu m.

[0025] A high-temperature-resistant and high-strength aluminum alloy material, the synthesis raw materials include metal copper, metal magnesium, metal nickel, metal scandium, metal zirconium, metal manganese, metal titanium, graphene and acetylene, and the balance is metal aluminum.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] 1、The alloy component designed in the present application realizes the synergy of multiple strengthening mechanisms; the copper and magnesium form the nano-strengthening phase through solid solution and precipitation to lay the foundation for high strength; the scandium and zirconium form the stable dispersion phase to pin the grain boundaries and dislocations, thereby improving the yield strength and creep resistance; the nickel and manganese form the micron dispersion phase to hinder the grain boundary migration, thereby enhancing the room temperature strength and corrosion resistance; the graphene nanosheet further strengthens through load transmission and constructs a full-scale network, and the obtained aluminum alloy has a tensile strength of 625MPa and a yield strength of 552MPa, thereby improving the overall mechanical properties of the material.

[0028] 2、The application adopts fine preparation process, avoids element burning loss and agglomeration by step-by-step smelting, ensures full alloying, eliminates segregation and refines grains by stage heat treatment, provides supersaturated solid solution, precisely controls precipitated phase by three-stage aging treatment, strengthens effect and improves high-temperature stability, ensures alloy pure and uniform, optimizes distribution of strengthening phase, endows material with excellent stable mechanical and heat-resistant performance, the strength retention rate reaches 61% under 300 DEG C high-temperature condition, and the reliability under complex working conditions is improved.

[0029] 3、On the basis of the performance of the alloy body, the surface is modified by depositing a diamond-like carbon layer at low temperature by using plasma chemical vapor deposition technology, a dense barrier is formed by using the carbon layer to improve high-temperature oxidation resistance and delay corrosion; the high hardness and wear resistance of the carbon layer improve the surface hardness and improve the high-temperature wear resistance; the low thermal conductivity of the carbon layer forms a thermal resistance, reduces internal heat transfer, protects the substrate from heat damage, prolongs the service life in extreme high-temperature environment, and improves the heat insulation effect, thereby improving the comprehensive performance in high-temperature harsh environment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The high-temperature tensile strength change curve of the high-temperature high-strength aluminum alloy material and the comparative example is shown in the following figure. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the application will be described in detail below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0032] The aluminum ingot is a high-purity aluminum ingot, the copper-aluminum alloy is Al-50%Cu, the aluminum-manganese alloy is Al-20%Mn, the aluminum-nickel alloy is Al-10%Ni, the aluminum-titanium alloy is Al-10%Ti, the aluminum-scandium alloy is Al-4%Sc, the aluminum-zirconium alloy is Al-4%Zr, and the graphene nanosheet is a multi-layer nanosheet structure with a sheet diameter of 5-10 μm.

[0033] Please refer to Figure 1 The application provides a high-temperature-resistant high-strength aluminum alloy material and a preparation method thereof, and the technical scheme is as follows:

[0034] Embodiment 1

[0035] In a vacuum induction melting furnace, the aluminum ingot is placed in a graphite crucible under argon protection, heated to 780℃ to completely melt, and then the copper-aluminum alloy is added, the temperature is kept at 740℃, the stirring speed is 200r / min, and the stirring time is 10min; then the aluminum-manganese alloy, aluminum-nickel alloy and aluminum-titanium alloy are added, and the mixed solution is obtained by keeping the temperature and stirring for 20min at a speed of 200r / min; the multilayer graphene nanosheet with a mass ratio of 0.4% is precisely wrapped with high-purity aluminum foil, and is pressed into the mixed solution using a bell jar, and then the powerful mechanical stirring is started at 720℃, the stirring speed is kept at 200r / min, and the stirring time is 10min; then the aluminum-scandium alloy and aluminum-zirconium alloy are added, the temperature is kept at 700℃, the stirring speed is adjusted to 100r / min, and the stirring time is 20min to obtain the melted alloy.

[0036] The hexachloroethane is added to the melted alloy, the amount of hexachloroethane added is 0.5% of the mass of the melted alloy, the temperature is controlled at 740℃, the heat preservation time is 10min, argon is introduced for refining treatment, the argon flow is controlled at 0.2L / min, and the refining time is 15min to obtain the refined alloy; the dry lithium salt composite agent is added to the refined alloy, the mass percentage is 0.05% of the mass of the melted alloy, the low-speed stirring time is 4min, the stirring speed is 60r / min, then the surface scum is removed after standing for 10min, and the cast alloy is poured into a metal mold preheated to 250℃ and rapidly cooled to obtain the cast alloy;

[0037] The cast alloy is subjected to solid solution treatment by stage heat treatment; the cast alloy is placed in a 500℃ vacuum drying oven for homogenization annealing treatment for 24h, air cooling is performed at a cooling speed of less than 5℃ / min, and the cast segregation is eliminated to make the elements uniformly distributed to obtain the annealed aluminum ingot; the annealed aluminum ingot is heated to 450℃ for hot working treatment to obtain the processed material; the processed material is heated to 520℃ for solid solution treatment for 2h, and then rapidly water quenched with a quenching time of less than 5s to obtain the solid solution;

[0038] The solid solution is subjected to three-stage aging treatment under nitrogen protection; the first stage temperature is 120℃, the heat preservation time is 5h, and the cooling speed is kept at 10℃ / min; the second stage temperature is 190℃, the heat preservation time is 7h, and the cooling speed is kept at 8℃ / min; the third stage temperature is 210℃, the heat preservation time is 3h, and the cooling temperature is kept at 4℃ / min to obtain the aluminum alloy precursor;

[0039] The aluminum alloy precursor is added into the PECVD vacuum chamber, the tubular furnace is vacuumized to 5 Pa, argon is continuously introduced into the furnace cavity at 25 mL / min, the power is kept at 400 W, and ion bombardment is performed for 20 min to obtain a treated aluminum alloy; the treated aluminum alloy is introduced into a mixed gas of acetylene and argon, wherein the volume ratio of acetylene to argon is 1:5, the flow rate is kept at 55 mL / min, carbon layer deposition is performed, the vacuum degree is kept at 15 Pa, the deposition temperature is 180℃, the deposition time is 2.5 h, and the aluminum alloy material is obtained by natural cooling to room temperature under vacuum condition.

[0040] Example 2-5 Refer to the preparation method and parameter conditions of Example 1, the differences are shown in Table 1.

[0041] Table 1 Parameter changes of Examples 1-5

[0042]

[0043] Comparative Example 1 Refer to Example 1, the difference is that copper, magnesium and nickel elements are not introduced, and other elements remain unchanged.

[0044] Comparative Example 2 Refer to Example 1, the difference is that scandium and zirconium elements are not introduced, and the percentage content of other elements remains unchanged.

[0045] Comparative Example 3 Refer to Example 1, the difference is that manganese and titanium elements are not introduced, and the percentage content of other elements remains unchanged.

[0046] Comparative Example 4 Refer to Example 1, the difference is that multi-layer graphene is not used for co-melting.

[0047] Comparative Example 5 Refer to Example 1, the difference is that the multi-layer graphene is not wrapped with aluminum foil.

[0048] Comparative Example 6 Refer to Example 1, the difference is that hexachloroethane refining treatment is not used.

[0049] Comparative Example 7 Refer to Example 1, the difference is that lithium salt complexing agent is not used as a grain refiner.

[0050] Comparative Example 8 Refer to Example 1, the difference is that it is not subjected to staged heat treatment, but directly subjected to aging treatment.

[0051] Comparative Example 9 Refer to Example 1, the difference is that it is not subjected to three-stage aging treatment, but only uses the first stage and the second stage.

[0052] Comparative Example 10 Refer to Example 1, the difference is that it is not subjected to three-stage aging treatment, but uses the second stage and the third stage.

[0053] Comparative Example 11 Refer to Example 1, the difference is that it is not subjected to carbon layer deposition treatment.

[0054] Experimental Example 1 Test of Mechanical Properties

[0055] The aluminum alloy materials prepared from Examples 1-5 and Comparative Examples 1-11 were subjected to test of mechanical properties, and the tensile strength, yield strength and tensile rate of the aluminum alloy materials were tested according to GB / T228.1-2021, and the results are shown in Table 2.

[0056] Table 2 Test Results of Examples and Comparative Examples

[0057]

[0058] From the results of Table 2, it can be seen that in the comparative examples, by changing the types of added elements and the process, the mechanical properties of the aluminum alloy material obtained are significantly lower than those of the examples; in Comparative Example 1, copper, magnesium and nickel are the most important solid solution strengthening and aging precipitation strengthening elements in the aluminum alloy. Without adding these elements, the alloy will lose the main strengthening mechanism and cannot form high-strength precipitates, resulting in a significant decrease in strength and yield strength, becoming a relatively soft alloy. Although the elongation is improved, it is at the expense of strength, and the overall mechanical properties decrease significantly; in Comparative Example 2, without the introduction of scandium and zirconium elements, the dispersed phase cannot be formed during solidification, and the grains cannot be effectively refined. Coarse grains will lead to a decrease in strength and toughness; the results of Comparative Example 3, manganese can form Al-Mn phase to improve corrosion resistance and room temperature strength, titanium element as a grain refiner, inhibits the further growth of grains, lack of post-grain coarsening, corrosion resistance decreases, resulting in a decrease in strength and elongation; in Comparative Examples 4-5, without the introduction of multi-layer graphene nanosheets as high-efficiency reinforcing phase, the dispersion strengthening effect is missing, and the alloy's strength and hardness cannot be improved through the load transfer mechanism. In addition, the lack of dislocation pinning will reduce the strengthening effect of the alloy. However, without using aluminum foil to wrap the graphene nanosheets, the graphene will be oxidized in the high-temperature aluminum melt during high-temperature smelting, thereby losing the reinforcing effect. In addition, the untreated graphene is severely agglomerated, resulting in uneven distribution in the matrix. The agglomerates will become stress concentration sources, reducing the strength and toughness of the alloy; as can be seen from the results of Comparative Examples 6-7, hexachloroethane as a refining agent has the function of degassing and deslagging. Without its use, the hydrogen content in the aluminum alloy material is high, leading to an increase in casting defects. In addition, non-metallic inclusions such as oxides cannot be effectively removed. The existence of these defects will become stress concentration points, significantly reducing the strength and toughness of the alloy; lithium salt complexing agent as a grain refiner can optimize the solidification structure, making it more uniform and fine. Without its use, the mechanical properties of the aluminum alloy are less affected by the poor uniformity of the structure; in Comparative Example 8, by skipping the homogenization annealing, hot working and solid solution treatment processes, the casting segregation is not eliminated, the grains cannot be further refined, and without solid solution treatment, the alloying elements cannot be fully dissolved into the matrix, resulting in insufficient or uneven distribution of the aging precipitates, and the overall mechanical properties decrease; in Comparative Examples 9-10, the purpose of three-stage aging treatment is to optimize the morphology, size and distribution of the precipitates to achieve the best strength and high-temperature stability. Without the fine control of the initial stage, high-temperature aging may more easily lead to overaging, making the precipitates coarse and reducing the strength of the alloy; without high-temperature aging treatment, the stability of the precipitates is poor, which further affects the overall mechanical strength.

[0059] In summary, by introducing high-temperature strengthening elements such as scandium, zirconium, nickel and multi-layer graphene nanosheets on the basis of traditional high-strength aluminum alloy, and combining multi-stage, refined melting, heat treatment and surface modification processes, the synergistic effect of multiple strengthening mechanisms is achieved. First, copper, magnesium and nickel form a strengthening phase core through solid solution and aging precipitation, providing the basic strength and hardness of the alloy, and scandium and zirconium form a dispersion phase that effectively pins the grain boundaries and dislocations, stabilizing the structure; the uniformly dispersed graphene nanosheets, as a second phase particle, further enhance the strength, hardness and modulus of the alloy through load transfer, while also helping to hinder crack propagation; second, from the segmented melting process to the staged heat treatment, and then the three-stage aging treatment, the strengthening phase precipitation is precisely controlled, and the aluminum alloy is homogenized and stabilized to ensure the purity, uniformity of the structure and the optimal state of the precipitated phase; finally, by combining the internal high-strength, high-toughness and high-temperature-resistant alloy matrix with the external high-hardness, wear-resistant and heat-insulating carbon layer, the aluminum alloy material is endowed with improved mechanical properties through the synergistic effect of multiple elements and the combination of multiple processes.

[0060] Comparative Example 12 Referring to Example 1, the difference is that it does not undergo homogenization annealing treatment, and the subsequent treatment process remains unchanged.

[0061] Comparative Example 13 Referring to Example 1, the difference is that it does not undergo hot working treatment, and the other treatment processes remain unchanged.

[0062] Comparative Example 14 Referring to Example 1, the difference is that it does not undergo solid solution treatment, and the other treatment processes remain unchanged.

[0063] Comparative Example 15 Referring to Example 1, the difference is that it does not use step melting during the alloy melting process, but directly high-temperature blending melting.

[0064] Experimental Example 2 Heat Resistance Test

[0065] The aluminum alloy materials obtained in Examples 1-5 and Comparative Examples 1-5, Comparative Example 8, Comparative Examples 12-15 were subjected to heat resistance tests. The high-temperature strength retention rate was tested according to GB / T 4338-2015, the test temperature was 300℃, and the tensile strength was tested after 100h of heat preservation. The tensile strength retention rate was obtained by comparing the test results at room temperature. The high-temperature creep properties of the aluminum alloy were tested according to GB / T 2039-2012, and the steady-state creep rate was tested at 350℃ and 100MPa. The test results are shown in Table 3. The change curve of the high-temperature tensile strength of Examples 1-3 and Comparative Examples 12-15 is shown in Figure 1

[0066] Table 3 Test Results of Examples and Comparative Examples

[0067] ​

[0068] From the results of Table 3, it can be seen that in the comparative examples, by changing the types of added elements and the process, the heat resistance of the aluminum alloy material obtained is significantly reduced compared to the examples; in Comparative Example 1, Cu and Mg are key elements for forming the main strengthening phases S phase and θ phase, and their absence causes the alloy to lose the most important precipitation strengthening effect, resulting in a decrease in mechanical strength; the absence of Ni weakens the stability of the dispersed phase at high temperatures; in Comparative Example 2, Sc and Zr form Al3(Sc, Zr) core-shell structure particles to form stable high-temperature strengthening phases, pinning grain boundaries and dislocations, effectively inhibiting high-temperature creep, and after the absence of the alloy, the anti-creep skeleton is lost, the high-temperature creep rate deteriorates sharply, and the strength decreases significantly; in Comparative Example 3, the absence of titanium element will lead to coarse casting grains, affecting the plasticity and strength; manganese element can form dispersed Al-Mn intermetallic compounds to achieve dispersion strengthening and hinder grain boundary migration, and after the absence of the alloy, the comprehensive performance and organizational uniformity will decrease; in Comparative Examples 4-5, without using aluminum foil wrapping, graphene will be rapidly oxidized and burned in the high-temperature aluminum liquid, and cannot be uniformly dispersed in the matrix; the alloy load transfer fails, and the dislocation pinning effect is also lost, and the dislocations can ignore the agglomeration of graphene at high temperatures, resulting in a decrease in high-temperature strength and creep resistance; in Comparative Example 8, combined with the results of Comparative Examples 12-14, without going through the staged heat treatment process, a coarse, loose, and composition-uniform as-cast structure is formed, and without solid solution treatment, the aluminum alloy has no strengthening characteristics and cannot effectively form uniform dispersed phases and strengthening phases, resulting in poor overall performance; in Comparative Example 15, step melting is the key to ensuring uniform alloy composition and effective element melting, and direct high-temperature blending will cause elements with large melting point differences to be unable to fully alloy, in addition, active elements will burn out too early at high temperatures, affecting overall performance, and the premature addition of graphene will cause high-temperature damage. The alloy composition is uneven, the organization has many defects, and the overall performance is greatly reduced.

[0069] In summary, in one aspect, the application forms Al3(Sc, Zr) particles of nanoscale as a heat-resistant skeleton through the synergistic effect of components, Sc / Zr, to resist creep; Ni / Mn forms a micron-sized dispersion phase to pin the grain boundary and inhibit recrystallization; the addition of Cu and Mg forms a large number of nanoscale strengthening phases to provide the basic high strength of the alloy, forming a full-scale strengthening network from atomic scale to nanoscale to micrometer scale, with multiple mechanisms complementing each other to resist deformation; on the other hand, through the synergy of smelting and forming processes, homogenization annealing provides a uniform structure for hot working, hot working provides a fine-grained basis for solid solution treatment, and solid solution treatment provides a supersaturated solid solution for aging treatment, three-stage aging fine-tunes the size and distribution of precipitates to maximize the strengthening effect; by utilizing the synergistic effect of various additive elements in aluminum alloys and combining process synergy, an excellent internal microstructure is constructed to improve the heat resistance of aluminum alloy materials and improve the application effect of aluminum alloy materials in the field of engines and aerospace.

[0070] Examples 6-8 refer to the preparation method and parameter conditions of Example 1, the difference is shown in Table 4.

[0071] Table 4 Parameter changes of Example 1, Examples 6-8

[0072]

[0073] Comparative Example 4 refers to Example 1, the difference is that no multi-layer graphene is used for co-smelting.

[0074] Comparative Example 11 refers to Example 1, the difference is that no carbon layer deposition treatment is performed.

[0075] Comparative Example 16 refers to Example 1, the difference is that no plasma-enhanced chemical vapor deposition carbon layer is used, and conventional chemical vapor deposition is used.

[0076] Experimental Example 3 Surface hardness and thermal insulation performance test

[0077] The aluminum alloy materials prepared in Example 1, Examples 6-8, Comparative Example 4, Comparative Example 11, and Comparative Example 16 were tested for surface hardness and thermal insulation performance, the Vickers hardness was tested according to GB / T 3854-2019, and the thermal insulation effect was tested according to GB / T 31390-2015; the test results are shown in Table 5.

[0078] Table 5 Test results of examples and comparative examples

[0079]

[0080] From the results of Table 5, it can be seen that in the comparative examples, by changing the deposition process and the multi-layer graphene, the surface properties of the aluminum alloy are significantly reduced compared to the examples; in Comparative Example 4, the absence of the reinforcing effect of graphene results in a relatively low matrix hardness, and even with the deposition of a carbon layer, the overall surface hardness is reduced. In addition, the presence of graphene in the aluminum alloy matrix can form an interfacial thermal resistance, reducing the thermal conductivity of the material and improving the thermal insulation performance. Due to the extremely high hardness and wear resistance of the carbon layer, in Comparative Example 11, which has not undergone carbon layer deposition treatment, the surface hardness is only dependent on the performance of the aluminum alloy matrix, which is significantly lower than the examples. At the same time, the thermal conductivity of carbon materials is relatively low, especially when forming a dense film, which can effectively hinder the transfer of heat, and the absence of heat is more easily conducted through the aluminum alloy matrix, increasing the thermal damage to the aluminum alloy matrix. In Comparative Example 16, PECVD, compared to conventional CVD, can provide higher energy through the action of plasma, making it easier for carbon atoms to deposit and form a dense, uniform, and more strongly bonded film. In addition, PECVD can be deposited at a lower temperature, reducing damage to the substrate. Conventional CVD results in insufficient carbon layer density, poor adhesion, or defects, further affecting its hardness and thermal insulation effect.

[0081] In summary, the existing high-temperature-resistant aluminum alloy material is prone to oxidation and wear on the surface when working in a high-temperature environment. The introduction of a dense diamond-like carbon film forms a physical barrier on the surface of the aluminum alloy, effectively preventing oxygen from contacting the aluminum alloy matrix, significantly improving the material's oxidation resistance, and delaying high-temperature oxidation corrosion. In addition, the indirect increase in hardness also greatly improves the material's wear resistance at high temperatures. The addition of a carbon layer can form a thermal resistance layer on the material's surface using the relatively low thermal conductivity of carbon materials, which helps to reduce the transfer of heat to the alloy interior, thereby improving the overall thermal insulation performance of the material. For aluminum alloy materials that need to withstand high temperatures, this increases the service life and stability in high-temperature environments. The role of the deposition layer is to further optimize and enhance the surface performance of the alloy in a specific high-temperature environment, making it more suitable for high-temperature-resistant applications. As shown in Table 2, the introduction of a carbon layer has a relatively small effect on the macroscopic tensile mechanical properties of the aluminum alloy (tensile strength, yield strength, and tensile rate). The main effect is the improvement in surface performance. However, under extreme high-temperature service conditions, a dense carbon layer acts as a physical barrier to effectively prevent oxidation and wear, thereby significantly improving the material's long-term stability and service life, ensuring that the overall performance of the aluminum alloy material remains stable in harsh environments. The introduction of a dense carbon layer provides additional surface hardness, oxidation resistance, and thermal insulation capabilities, enabling the material to exhibit superior overall performance in high-temperature-resistant applications.

[0082] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a high-temperature resistant, high-strength aluminum alloy material, characterized in that, Includes the following steps: A smelted alloy is obtained by stepwise smelting aluminum ingots with copper-aluminum master alloys, aluminum-manganese alloys, aluminum-nickel alloys, aluminum-titanium alloys, metallic magnesium, aluminum-scandium alloys, aluminum-zirconium alloys, and graphene nanosheets. The smelted alloy was refined with hexachloroethane, and a dried lithium salt composite agent was added to the refined alloy. The mixture was stirred and allowed to stand for 10 minutes before being cast to obtain the casting alloy. The cast alloy was subjected to a staged heat treatment to obtain a solid solution. The staged heat treatment includes the following steps: placing the cast alloy in a vacuum drying oven at 480-500℃ for homogenization annealing for 24 hours, followed by air cooling to obtain annealed aluminum ingots; heating the annealed aluminum ingots to 440-460℃ for heat treatment for 2 hours to obtain processed materials; heating the processed materials to 510-540℃ for solution treatment for 2 hours, followed by rapid water quenching to obtain the solid solution; The solid solution is subjected to a three-stage aging process to obtain an aluminum alloy precursor; the aluminum alloy precursor is subjected to plasma chemical vapor deposition and naturally cooled to room temperature to obtain the high-temperature resistant and high-strength aluminum alloy material. The plasma chemical vapor deposition includes the following steps: adding the aluminum alloy precursor into a vacuum chamber, evacuating the tubular furnace, continuously introducing argon gas into the furnace chamber, maintaining the working power, and bombarding with ions to obtain the treated aluminum alloy; introducing a mixture of acetylene and argon gas into the treated aluminum alloy to perform carbon layer deposition. The three-stage aging process includes the following steps: carried out under nitrogen protection, with the first stage temperature at 110-120℃ and the holding time at 4-6h; the second stage temperature at 180-190℃ and the holding time at 6-8h; and the third stage temperature at 200-210℃ and the holding time at 2-4h, to obtain the aluminum alloy precursor. The aluminum ingot is a high-purity aluminum ingot; the copper-aluminum master alloy is Al-50%Cu; the aluminum-manganese alloy is Al-20%Mn; the aluminum-nickel alloy is Al-10%Ni; the aluminum-titanium alloy is Al-10%Ti; the aluminum-scandium alloy is Al-4%Sc; the aluminum-zirconium alloy is Al-4%Zr; the graphene nanosheets are multilayer nanosheet structures with a sheet diameter of 5-10μm; The high-temperature resistant and high-strength aluminum alloy material comprises, by mass percentage, 5.2-5.8% copper, 0.8-1.2% magnesium, 0.2-0.3% scandium, 0.1-0.2% zirconium, 1.5-2.5% nickel, 0.4-0.9% manganese, 0.08-0.15% titanium, and 0.3%-0.5% graphene, with the balance being aluminum. The lithium salt composite agent is a powder made by mixing lithium carbonate and lithium fluoride in a mass ratio of 3:

1.

2. The method for preparing a high-temperature resistant and high-strength aluminum alloy material according to claim 1, characterized in that, The step-by-step smelting includes the following steps: In a vacuum induction melting furnace under argon protection, the aluminum ingot is placed in a graphite crucible and heated until completely melted. The copper-aluminum master alloy is added, and the temperature is maintained while stirring. Then, the aluminum-manganese alloy, the aluminum-nickel alloy, and the aluminum-titanium alloy are added, and the mixture is kept warm and stirred to obtain a mixed solution. The graphene nanosheets are precisely wrapped with high-purity aluminum foil and pressed into the mixed solution using a bell jar, and mechanically stirred to obtain a homogeneous solution. The homogeneous solution is cooled, and the magnesium metal is added. Under stirring conditions, the aluminum-scandium alloy and the aluminum-zirconium alloy are added, and the temperature is maintained while stirring to obtain the smelted alloy.

3. The method for preparing a high-temperature resistant and high-strength aluminum alloy material according to claim 1, characterized in that, The preparation of the casting alloy includes the following steps: The hexachloroethane is added to the smelted alloy, the temperature is controlled, and argon gas is introduced for refining to obtain a refined alloy; the dried lithium salt composite agent is added to the refined alloy, and the mixture is cast into a preheated metal mold and rapidly cooled to obtain the casting alloy.

4. A high-temperature resistant, high-strength aluminum alloy material, characterized in that: The high-temperature resistant and high-strength aluminum alloy material is prepared by the preparation method described in any one of claims 1-3.

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