Preparation method of high-heat-resistant aluminum alloy

Abstract

This invention discloses a method for preparing high heat-resistant aluminum alloys, belonging to the field of non-ferrous metal manufacturing technology. The invention prepares copper-clad aluminum composite powder, iron-clad aluminum composite powder, and nickel-clad aluminum composite powder via chemical plating. The powders are mixed in a certain proportion and slightly oxidized in air before being vacuum-clad. The clad powder ingots are then subjected to hot isostatic pressing or hot extrusion densification treatment. During densification, a dual process of internal oxidation and precipitation of nano-heat-resistant phases occurs, ultimately forming two nano-scale heat-resistant phases, Al2O3 and AlFeNiCu intermetallic compounds, in the aluminum alloy, significantly improving the heat resistance of the aluminum alloy.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal manufacturing technology, and specifically relates to a method for preparing a high heat-resistant aluminum alloy. Background Technology

[0002] Aluminum alloys, due to their lightweight, high strength, wear and corrosion resistance, low density, high specific strength, and good heat resistance, are widely used in the automotive, aerospace, and other fields. With increasingly stringent requirements for green environmental protection and a circular economy, the heat resistance of aluminum alloys in weaponry, shipbuilding, aviation, aerospace, and automotive industries is facing more stringent demands. Although most aluminum alloys exhibit good comprehensive mechanical properties at room temperature, the problem of high-temperature softening remains a key weakness restricting the structural design and service safety of parts in the medium-to-high temperature range. Traditional aluminum alloys struggle to meet the demanding requirements of high temperature resistance and high specific strength in some fields. For example, the tensile strength of the representative 7075 aluminum alloy is only 30% and 10% of that at room temperature at 200℃ and 300℃, respectively. Even the most commonly used cast heat-resistant aluminum alloys, such as A319, A380, and ZL702A, which have been successfully commercialized in the automotive manufacturing industry, cannot meet the requirements of new high-power engines (operating temperatures of 300-400℃) or other higher heat-resistant applications. The main reason is that its process characteristics result in low element solid solubility, making it difficult to form precipitates with a sufficiently high volume fraction in the aluminum alloy matrix. Furthermore, when the service temperature exceeds 200℃, the internal strengthening phases such as Mg2Si, Al2Cu, and Al2CuMg will gradually coarsen, greatly reducing the strengthening effect of the precipitates and causing a sharp decline in the high-temperature mechanical properties of the aluminum alloy.

[0003] Alumina, as a ceramic compound that can improve the heat resistance of aluminum alloys, has been applied in the production of heat-resistant aluminum alloys. Its traditional preparation process mainly involves oxidizing the surface of aluminum alloy powder and then heating and extruding the powder to prepare alumina-reinforced aluminum alloys. However, this method only adds the alumina phase to the surface of the alloy powder, and cannot achieve nanoscale addition of the alumina phase or ensure uniform dispersion of the alumina phase within the alloy after hot extrusion. Furthermore, AlFeNiCu is a highly thermally stable intermetallic compound; when present in aluminum alloys, it does not coarsen or grow below 400°C. Therefore, if nanoscale AlFeNiCu compounds can be added to aluminum alloys and their uniform dispersion can be ensured, the heat resistance of the aluminum alloy can be greatly improved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a high heat-resistant aluminum alloy, so as to solve the problem of poor high-temperature resistance of aluminum alloy materials in the prior art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a high heat-resistant aluminum alloy includes the following steps:

[0007] Step 1, Chemical plating of aluminum powder surface: Copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are prepared by surface plating of aluminum powder with copper, iron, and nickel respectively.

[0008] Step 2, Slight oxidation and cladding: Copper-clad aluminum powder, iron-clad aluminum powder and nickel-clad aluminum powder are mixed in a mass ratio of 1:4-6:0.8-1.2. After the mixed powder is kept at 180-220℃ in an air atmosphere for 20-40 minutes, it is filled into a pure aluminum cladding and vacuum sealed to obtain a clad powder billet.

[0009] By heat-insulating the mixed powder in air, its surface is slightly oxidized to form copper oxide-coated aluminum powder, iron oxide-coated aluminum powder, and nickel oxide-coated aluminum powder. By controlling the oxidation time and temperature, the degree of surface oxidation and the oxygen content dissolved into the alloy in subsequent processes can be controlled. Then, the mixed powder is filled into a pure aluminum sheath, vacuumed, and sealed.

[0010] Step 3, Densification of metal billet: Hot isostatic pressing or hot extrusion deformation of the encapsulated powder billet to obtain a high heat-resistant aluminum alloy billet.

[0011] The hot isostatic pressing process is carried out at a temperature of 500-540℃, a pressure of 100-200MPa, and a holding time of 1-3h.

[0012] The heating temperature for the hot extrusion deformation is 450-550℃, the holding time is 1-2h, and the extrusion ratio is 10-15.

[0013] By performing hot isostatic pressing (HIP) on the encapsulated powder ingot, an internal oxidation process occurs in the powder during HIP. Specifically, aluminum in the composite powder undergoes a reduction reaction with copper oxide, iron oxide, and nickel oxide, resulting in the formation of a large amount of nano-sized alumina within the aluminum alloy powder. Furthermore, during HIP, the alloying elements Fe, Ni, and Cu diffuse and react in the solid state to form a large number of uniformly distributed nano-sized AlFeNiCu heat-resistant phases within the powder. These nano-sized Al2O3 and AlFeNiCu heat-resistant phases hinder grain growth and dislocation movement, thereby suppressing high-temperature creep. Simultaneously, the powder particles bond together during HIP to form a dense alloy ingot, resulting in a dense, high-heat-resistant aluminum alloy.

[0014] By hot extrusion deformation of the encapsulated powder ingot, the alloying elements undergo the aforementioned internal oxidation process during the heat preservation process, forming a large number of dispersed Al2O3 nanoparticles inside each powder. The alloying elements diffuse and precipitate to form nanoscale AlFeNiCu heat-resistant phases inside the powder, ultimately forming a high heat-resistant aluminum alloy with uniform composition and dispersed precipitates. Then, the hot extrusion process causes metallurgical bonding between the powders to achieve densification. At the same time, the extrusion deformation breaks down the structure of the powder, forming more small-sized grains to further improve the performance of the alloy.

[0015] As a further aspect of the present invention, the vacuum degree of the vacuum seal in step 2 is 10. -3 -10 -4 Pa.

[0016] The method for preparing the copper-clad aluminum powder includes the following steps:

[0017] Atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min to remove surface aluminum oxide. Ethanol is added to zinc sulfate solution to obtain an ethanol-zinc sulfate mixed solution. The filtered aluminum powder is then immersed in the ethanol-zinc sulfate mixed solution for 20-30 min. After filtration, the aluminum powder is immersed in an acidic copper sulfate solution and stirred at 40-80℃ for 10-30 min. After the aluminum powder surface is fully coated with copper, the plating solution and powder are quickly filtered. The filtered powder is then washed and dried to obtain copper-coated aluminum powder.

[0018] As a further embodiment of the present invention, the dilute alkaline solution is a sodium hydroxide solution with a concentration of 0.03-0.1 mol / L.

[0019] As a further embodiment of the present invention, the concentration of the zinc sulfate solution is 20-80 g / L, and the ethanol is analytical grade ethanol.

[0020] As a further aspect of the present invention, the volume of the ethanol is 5-15% of the volume of the zinc sulfate solution.

[0021] As a further embodiment of the present invention, the concentration of the acidic copper sulfate solution is 40-100 g / L, and the pH is adjusted to 1.5-4.5 with 98% concentrated sulfuric acid.

[0022] The preparation method of the iron-clad aluminum powder includes the following steps:

[0023] The atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min to remove the surface aluminum oxide. Citric acid solution is added to the ferrous sulfate solution to obtain a citric acid-ferrous sulfate mixed solution. The filtered aluminum powder is then immersed in the citric acid-ferrous sulfate mixed solution at 25-100℃ for 1-20 min. The filtered powder is then washed and dried to obtain iron-coated aluminum powder.

[0024] As a further embodiment of the present invention, the concentration of the ferrous sulfate solution is 35-90 g / L, and the concentration of the citric acid solution is 4-40 g / L.

[0025] As a further aspect of the present invention, the volume of the citric acid solution is 5-15% of the volume of the ferrous sulfate solution.

[0026] The preparation method of the nickel-coated aluminum powder includes the following steps:

[0027] Immerse the atomized aluminum powder in a dilute alkaline solution for 0.5-1 min to remove the surface aluminum oxide. Add ethanol to the nickel sulfate solution to obtain an ethanol-nickel sulfate mixed solution. After filtering, immerse the powder in the ethanol-nickel sulfate mixed solution and stir at 50-60℃ until the solution becomes colorless. Continue the reaction for 25-35 min. Filter out the powder, wash and dry it to obtain nickel-coated aluminum powder.

[0028] As a further embodiment of the present invention, the concentration of the nickel sulfate solution is 30-70 g / L, and the ethanol is analytical grade ethanol.

[0029] As a further aspect of the present invention, the volume of the ethanol is 5-15% of the volume of the nickel sulfate solution.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. This invention provides a method for preparing high heat-resistant aluminum alloys. Copper-clad aluminum composite powder, iron-clad aluminum composite powder, and nickel-clad aluminum composite powder are prepared by chemical plating. The powders are mixed in a certain proportion and slightly oxidized in air before being vacuum-clad. The clad powder ingot is then subjected to hot isostatic pressing or hot extrusion densification treatment. During the densification process, a dual process of internal oxidation and precipitation of nano-heat-resistant phases occurs. Ultimately, by forming two nano-scale heat-resistant phases, Al2O3 and AlFeNiCu intermetallic compounds, in the aluminum alloy, the heat resistance of the aluminum alloy is significantly improved.

[0032] 2. Copper-clad aluminum composite powder, iron-clad aluminum composite powder, and nickel-clad aluminum composite powder prepared by chemical plating can completely coat the surface of aluminum powder with copper, iron, and nickel, thereby forming a stable and tightly sealed outer shell on the aluminum core powder. By controlling the concentration of the chemical plating solution and the reaction time, the thickness of the coated shell can be controlled, thereby controlling the content of nano-sized alumina and nano-sized AlFeNiCu intermetallic compounds in the final heat-resistant aluminum alloy.

[0033] 3. By controlling the processing time and temperature during the slight oxidation treatment of the powder, the degree of oxidation on the powder surface can be controlled, thereby controlling the addition of oxygen. This allows for the control of the content of highly heat-resistant and highly stable nano-alumina in the alloy during the subsequent internal oxidation process. Compared to the traditional hot extrusion process after aluminum powder oxidation, the internal oxidation process used in this invention, while controlling the alumina content, produces alumina with a nanoscale size, significantly increasing the amount of alumina and thus greatly improving the heat resistance of the aluminum alloy.

[0034] 4. During hot isostatic pressing and hot extrusion, alloying elements Fe, Ni, and Cu undergo diffusion and solid solution precipitation. Due to the large specific surface area and small particle size of the powder, the diffusion and solid solution processes of the alloy components are relatively easy, thus forming a uniformly dispersed AlFeNiCu heat-resistant phase. Furthermore, since the AlFeNiCu heat-resistant phase is formed through a solid-state reaction, its size is small, reaching the nanoscale. After further hot forming, these heat-resistant phase particles pin and hinder the dislocation movement generated during the hot forming process, thereby improving the heat resistance of the alloy. Attached Figure Description

[0035] The present invention will now be further described with reference to the accompanying drawings.

[0036] Figure 1 These are microstructure images of the aluminum alloy billets prepared in Example 1 and Comparative Example 1 of this invention; Figure 1 Figure (a) shows the microstructure of the high heat-resistant aluminum alloy prepared in Example 1; Figure 1 Figure (b) shows the microstructure of the aluminum alloy obtained using conventional methods in Comparative Example 1;

[0037] Figure 2 The bar chart shows the initial hardness and hardness after heat treatment of aluminum alloy ingots prepared in Example 2 and Comparative Example 1 of this invention after being kept at 350°C for 100 hours. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] A method for preparing a high heat-resistant aluminum alloy includes the following steps:

[0040] Step 1, Chemical plating of aluminum powder surface: Copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are prepared by surface plating of aluminum powder with copper, iron, and nickel respectively.

[0041] The method for preparing the copper-clad aluminum powder includes the following steps:

[0042] Atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min to remove surface aluminum oxide. Ethanol is added to a zinc sulfate solution with a concentration of 20-80 g / L to obtain an ethanol-zinc sulfate mixed solution (the volume of ethanol is 5-15% of the volume of zinc sulfate solution). The filtered aluminum powder is immersed in the ethanol-zinc sulfate mixed solution for 20-30 min. After filtration, the aluminum powder is immersed in an acidic copper sulfate solution (concentration of 40-100 g / L, pH adjusted to 1.5-4.5 with 98% concentrated sulfuric acid). The mixture is stirred and reacted at 40-80℃ for 10-30 min. After the aluminum powder surface is fully coated with copper, the plating solution and powder are quickly filtered. The filtered powder is then washed and dried to obtain copper-coated aluminum powder.

[0043] The preparation method of the iron-clad aluminum powder includes the following steps:

[0044] Atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min to remove surface aluminum oxide. Citric acid solution with a concentration of 4-40 g / L is added to a ferrous sulfate solution with a concentration of 35-90 g / L to obtain a citric acid-ferrous sulfate mixed solution (the volume of citric acid solution is 5-15% of the volume of ferrous sulfate solution). The filtered aluminum powder is then immersed in the citric acid-ferrous sulfate mixed solution at 25-100℃ for 1-20 min. The filtered powder is then washed and dried to obtain iron-coated aluminum powder.

[0045] The preparation method of the nickel-coated aluminum powder includes the following steps:

[0046] Immerse the atomized aluminum powder in a dilute alkaline solution for 0.5-1 min to remove the surface aluminum oxide. Add ethanol to a nickel sulfate solution with a concentration of 30-70 g / L to obtain an ethanol-nickel sulfate mixed solution (the volume of ethanol is 5-15% of the volume of nickel sulfate solution). Immerse the filtered aluminum powder in the ethanol-nickel sulfate mixed solution and stir at 50-60℃ until the solution becomes colorless. Continue the reaction for 25-35 min. Filter out the powder, wash and dry it to obtain nickel-coated aluminum powder.

[0047] Step 2, Slight Oxidation and Coating: Copper-clad aluminum powder, iron-clad aluminum powder, and nickel-clad aluminum powder are mixed at a mass ratio of 1:4-6:0.8-1.2. After the mixed powder is kept at 180-220℃ in air for 20-40 minutes, it is filled into a pure aluminum casing, and a vacuum is drawn to a vacuum degree of 10. -3 -10 -4 Pa, vacuum sealed, to obtain a packaged powder billet;

[0048] Step 3, Densification of metal billet: The encapsulated powder billet is subjected to hot isostatic pressing at a temperature of 500-540℃, a pressure of 100-200MPa, and a holding time of 1-3h, or hot extrusion deformation at a temperature of 450-550℃, a holding time of 1-2h, and an extrusion ratio of 10-15 to obtain a high heat-resistant aluminum alloy billet.

[0049] Example 1

[0050] A method for preparing a high heat-resistant aluminum alloy includes the following steps:

[0051] Step 1, Chemical plating of aluminum powder surface: Copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are prepared by surface plating of aluminum powder with copper, iron, and nickel respectively.

[0052] The method for preparing the copper-clad aluminum powder includes the following steps:

[0053] Atomized aluminum powder was immersed in a 0.06 mol / L sodium hydroxide solution for 0.81 min to remove surface aluminum oxide. Ethanol was added to a 50 g / L zinc sulfate solution to obtain an ethanol-zinc sulfate mixed solution (the volume of ethanol was 10% of the volume of zinc sulfate solution). The filtered aluminum powder was immersed in the ethanol-zinc sulfate mixed solution for 25 min. After filtration, the aluminum powder was immersed in an acidic copper sulfate solution (70 g / L, pH adjusted to 3 with 98% concentrated sulfuric acid). The mixture was stirred at 60°C for 20 min. After the aluminum powder surface was fully coated with copper, the plating solution and powder were quickly filtered. The filtered powder was washed and dried to obtain copper-coated aluminum powder.

[0054] The preparation method of the iron-clad aluminum powder includes the following steps:

[0055] Atomized aluminum powder was immersed in a 0.06 mol / L sodium hydroxide solution for 0.8 min to remove surface aluminum oxide. A 28 g / L citric acid solution was added to a 65 g / L ferrous sulfate solution to obtain a citric acid-ferrous sulfate mixed solution (the volume of citric acid solution was 10% of the volume of ferrous sulfate solution). The filtered aluminum powder was then immersed in the citric acid-ferrous sulfate mixed solution and soaked at 60℃ for 12 min. The filtered powder was washed and dried to obtain iron-coated aluminum powder.

[0056] The preparation method of the nickel-coated aluminum powder includes the following steps:

[0057] Atomized aluminum powder was immersed in a 0.06 mol / L sodium hydroxide solution for 0.8 min to remove surface aluminum oxide. Ethanol was added to a 50 g / L nickel sulfate solution to obtain an ethanol-nickel sulfate mixed solution (the volume of ethanol was 10% of the volume of nickel sulfate solution). The filtered aluminum powder was immersed in the ethanol-nickel sulfate mixed solution and stirred at 55 °C until the solution became colorless. The reaction was continued for 30 min. The filtered powder was washed and dried to obtain nickel-coated aluminum powder.

[0058] Step 2, Slight Oxidation and Coating: Copper-clad aluminum powder, iron-clad aluminum powder, and nickel-clad aluminum powder are mixed in a mass ratio of 1:5:1. After the mixed powder is kept at 200℃ in air for 20 minutes, it is filled into a pure aluminum casing, and a vacuum is drawn to a vacuum degree of 10. - 4 Pa, vacuum sealed, to obtain a packaged powder billet;

[0059] Step 3, Densification of metal billet: The encapsulated powder billet is subjected to hot isostatic pressing at a temperature of 530℃, a pressure of 150MPa, and a holding time of 2h to obtain a high heat-resistant aluminum alloy billet.

[0060] Example 2

[0061] A method for preparing a high heat-resistant aluminum alloy includes the following steps:

[0062] Step 1, Chemical plating of aluminum powder surface: Copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are prepared by surface plating of aluminum powder with copper, iron, and nickel respectively.

[0063] The preparation methods for the copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are the same as in Example 1;

[0064] Step 2, Slight Oxidation and Coating: Copper-clad aluminum powder, iron-clad aluminum powder, and nickel-clad aluminum powder are mixed in a mass ratio of 1:5:1. After the mixed powder is kept at 200℃ in air for 30 minutes, it is filled into a pure aluminum casing, and a vacuum is drawn to a vacuum degree of 10. - 4 Pa, vacuum sealed, to obtain a packaged powder billet;

[0065] Step 3, Densification of metal billet: The encapsulated powder billet is subjected to hot extrusion deformation at a temperature of 500℃, a holding time of 1.5h, and an extrusion ratio of 13 to obtain a high heat-resistant aluminum alloy billet.

[0066] Comparative Example 1

[0067] Using conventional melting and casting methods, and taking into account the burn-off rate, the same alloy ratio as in Example 1 was used for weighing. The raw materials included pure aluminum blocks, pure fine iron wire, pure copper blocks, and pure nickel blocks. First, the iron wire was placed at the bottom of a graphite crucible, and then the pure aluminum blocks were placed on top. The crucible was heated to 800°C and held for 0.5 hours. Then, the temperature was lowered to 750°C, and the copper and nickel blocks were added and allowed to stand for 10 minutes. After degassing and slag removal, the crucible was allowed to stand for another 10 minutes. Finally, the solution was poured into a metal mold preheated to 250°C to obtain a conventionally melted and cast aluminum alloy.

[0068] Microstructure images of the aluminum alloy ingots prepared in Example 1 and Comparative Example 1 are shown below. Figure 1 As shown, Figure 1 Figure (a) shows the microstructure of the high heat-resistant aluminum alloy prepared in Example 1; Figure 1 Image (b) in the middle is a microstructure image of the aluminum alloy obtained using conventional methods in Comparative Example 1, for comparison. Figure 1 As can be seen from Figures (a) and (b), in Figure (a), a large number of fine Al2O3 and AlFeNiCu precipitates are dispersed on the aluminum matrix. These dispersed precipitates can significantly improve the strength and hardness of the alloy, and minimize the decrease in the plasticity and toughness of the alloy. They are stable under high temperature conditions and hinder the movement of dislocations, reducing the possibility of grain growth, thereby maintaining the strength and stability of the alloy material at high temperatures. In contrast, in Figure (b), the precipitates in the alloy billet prepared by the traditional process are not only large in size but also exhibit regional aggregation, which significantly weakens the plasticity and toughness of the alloy. At the same time, these large precipitates are also difficult to significantly hinder the movement of dislocations at high temperatures. Therefore, the high temperature strength and stability of the alloy are far inferior to those of the heat-resistant aluminum alloy prepared by the process of this invention.

[0069] After the aluminum alloy ingots prepared in Example 2 and Comparative Example 1 were simultaneously held at 350°C for 100 hours, the initial hardness and the hardness after holding were as follows: Figure 2 As shown, the original high-heat-resistant aluminum alloy (prepared in Example 2) has a Vickers hardness of 150.3. After 100 hours of heat preservation, the hardness value is 143.6, which is still much higher than the initial hardness of 110.7 and the hardness after heat preservation of the aluminum alloy obtained by conventional methods (prepared in Comparative Example 1) (62.4). This fully demonstrates that the high-temperature heat resistance of the aluminum alloy obtained by the process of this invention is greatly improved.

[0070] This invention prepares copper-clad aluminum composite powder, iron-clad aluminum composite powder, and nickel-clad aluminum composite powder. The powders are mixed in a certain proportion and slightly oxidized before being vacuum-clad. The clad powder ingot is then densified by hot isostatic pressing or hot extrusion. During the densification process, a dual process of internal oxidation and precipitation of nano-heat-resistant phases occurs. Ultimately, by forming two nano-scale heat-resistant phases, Al2O3 and AlFeNiCu intermetallic compounds, in the aluminum alloy, the heat resistance of the aluminum alloy is significantly improved.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high heat-resistant aluminum alloy, characterized in that, Includes the following steps: Step 1, Chemical plating of aluminum powder surface: Copper-coated aluminum powder, iron-coated aluminum powder, and nickel-coated aluminum powder are prepared by surface plating of aluminum powder with copper, iron, and nickel respectively. The surface copper plating involves immersing aluminum powder in an acidic copper sulfate solution and stirring the mixture at 40-80°C for 10-30 minutes. The concentration of the acidic copper sulfate solution is 40-100 g / L, and the pH is adjusted to 1.5-4.5 with 98% concentrated sulfuric acid. The surface iron plating involves immersing aluminum powder in a citric acid-ferrous sulfate mixed solution at 25-100℃ for 1-20 minutes; the ferrous sulfate solution concentration is 35-90 g / L, the citric acid solution concentration is 4-40 g / L, and the volume of the citric acid solution is 5-15% of the volume of the ferrous sulfate solution. The surface nickel plating involves immersing aluminum powder in an ethanol-nickel sulfate mixed solution, stirring at 50-60°C until the solution becomes colorless, and continuing the reaction for 25-35 minutes; the concentration of the nickel sulfate solution is 30-70 g / L, and the volume of ethanol is 5-15% of the volume of the nickel sulfate solution. Step 2, Slight oxidation and cladding: Copper-clad aluminum powder, iron-clad aluminum powder and nickel-clad aluminum powder are mixed in a mass ratio of 1:4-6:0.8-1.

2. After the mixed powder is kept at 180-220℃ in an air atmosphere for 20-40 minutes, it is filled into a pure aluminum cladding and vacuum sealed to obtain a clad powder billet. Step 3, Densification of metal billet: Hot isostatic pressing or hot extrusion deformation of the encapsulated powder billet to obtain a high heat-resistant aluminum alloy billet. The temperature of the hot isostatic pressing process is 500-540℃, the pressure is 100-200MPa, and the holding time is 1-3h. The heating temperature for hot extrusion deformation is 450-550℃, the holding time is 1-2h, and the extrusion ratio is 10-15.

2. The method for preparing a high heat-resistant aluminum alloy according to claim 1, characterized in that, The method for preparing the copper-clad aluminum powder includes the following steps: Atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min. Ethanol is added to zinc sulfate solution to obtain an ethanol-zinc sulfate mixed solution. The filtered aluminum powder is immersed in the ethanol-zinc sulfate mixed solution for 20-30 min. After filtration, the aluminum powder is immersed in an acidic copper sulfate solution and stirred at 40-80℃ for 10-30 min. The powder is then filtered out, washed, and dried to obtain copper-coated aluminum powder.

3. The method for preparing a high heat-resistant aluminum alloy according to claim 2, characterized in that, The concentration of the zinc sulfate solution is 20-80 g / L, and the volume of the ethanol is 5-15% of the volume of the zinc sulfate solution.

4. The method for preparing a high heat-resistant aluminum alloy according to claim 1, characterized in that, The preparation method of the iron-clad aluminum powder includes the following steps: Atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min. Citric acid solution is added to ferrous sulfate solution to obtain a citric acid-ferrous sulfate mixed solution. The filtered aluminum powder is immersed in the citric acid-ferrous sulfate mixed solution and soaked at 25-100℃ for 1-20 min. The filtered powder is washed and dried to obtain iron-coated aluminum powder.

5. The method for preparing a high heat-resistant aluminum alloy according to claim 1, characterized in that, The preparation method of the nickel-coated aluminum powder includes the following steps: The atomized aluminum powder is immersed in a dilute alkaline solution for 0.5-1 min. Ethanol is added to the nickel sulfate solution to obtain an ethanol-nickel sulfate mixed solution. After filtration, the powder is immersed in the ethanol-nickel sulfate mixed solution and stirred at 50-60℃ until the solution becomes colorless. The reaction continues for 25-35 min. The powder is filtered out, washed, and dried to obtain nickel-coated aluminum powder.

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