A high-strength heat-resistant Al-Fe-Cr-Ti alloy, preparation method and application

Abstract

The present invention discloses a high-strength and heat-resistant Al-Fe-Cr-Ti alloy, a preparation method and an application thereof, and belongs to the technical field of metal materials. The high-strength and heat-resistant aluminum alloy substrate comprises the following components: Fe 4.0-7.0wt.%, Cr 2.5-6.0wt.%, Ti 2.5-6.0wt.%, Co 3.0-7.5wt.%, rare earth La, Ce, Nd, Y totaling 0.5-2.5wt.%, and the balance being Al and unavoidable impurities. The present invention controls the content of the alloying elements Fe, Cr, and Ti, while adding the key alloying element Co and the rare earths La, Ce, Nd, and Y to match the alloy composition of the present invention, develops a processing method of spray deposition plus extrusion, and simultaneously controls the key processing technology to prepare a product having excellent comprehensive performance and heat resistance.

Description

Technical Field

[0001] The present invention relates to a heat-resistant aluminum-iron alloy and a preparation method thereof, in particular to a high-strength heat-resistant Al-Fe-Cr-Ti alloy, a preparation method and application thereof, and belongs to the technical field of metal materials. Background Art

[0002] With the development of aviation, aerospace, and military industries, there is an increasing demand for lightweight, high-specific strength, and high-specific stiffness heat-resistant aluminum alloys. Heat-resistant aluminum alloys have sufficient oxidation resistance at high temperatures, and are resistant to plastic deformation (creep) and damage under long-term temperature and load (dynamic and static) conditions. They also have good thermal conductivity and low density, making them a highly promising lightweight, high-temperature structural material for aviation and aerospace applications.

[0003] Heat-resistant aluminum alloys produced using traditional ingot metallurgical methods have slow solidification and cooling rates and low solid solubility of alloying elements in Al, which is not conducive to performance improvement and enhancement. Especially when used at temperatures reaching 300°C, the performance of the material drops sharply, limiting the scope of use of traditional heat-resistant aluminum alloys.

[0004] The present invention is based on an Al-Fe-Cr-Ti alloy, improves the high-temperature performance of the alloy by adding the alloying element Co and rare earth elements RE (La, Ce, Nd, Y), and simultaneously prepares an ingot by a rapid solidification method of spray deposition. The product obtained by combining the ingot with an extrusion processing method has excellent comprehensive performance and can still maintain high mechanical properties when used at temperatures above 300°C, thereby significantly improving the application range of the heat-resistant aluminum alloy. Summary of the Invention

[0005] The present invention aims to solve the problems of low mechanical properties and easy failure of conventional heat-resistant aluminum alloys at medium and high temperatures, and to provide a high-strength and heat-resistant Al-Fe-Cr-Ti alloy.

[0006] At the same time, the present invention provides a preparation method of a high-strength and heat-resistant Al-Fe-Cr-Ti alloy. The method controls the contents of the alloying elements Fe, Cr, and Ti, and simultaneously adds the key alloying elements Co and rare earth elements La, Ce, Nd, and Y. The ingot is prepared by a cooling method of rapid solidification through spray deposition, and the product produced by the extrusion processing method has excellent comprehensive performance and heat resistance.

[0007] Furthermore, through the design of the alloy composition and the matching processing methods, the product produced by the present invention possesses two characteristic phases: an Fe-containing phase and an Fe-containing quasicrystal phase. The Fe-containing phase is uniformly and dispersed in the matrix, with an average size of 0.8-1.5 μm. Simultaneously, nanometer-scale Fe-containing quasicrystals are uniformly and dispersed in the matrix, with an average size of 100-700 nm. This unique phase structure enables the material to maintain high mechanical properties even at high temperatures.

[0008] At the same time, the present invention provides an application of a high-strength and heat-resistant Al-Fe-Cr-Ti alloy in lightweight and high-temperature structural materials for aviation and aerospace.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A high-strength and heat-resistant Al-Fe-Cr-Ti alloy. The high-strength and heat-resistant aluminum alloy substrate comprises the following components: Fe 4.0-7.0wt.%, Cr 2.5-6.0wt.%, Ti 2.5-6.0wt.%, Co 3.0-7.5wt.%, rare earth La, Ce, Nd, and Y totaling 0.5-2.5wt.%, and the balance being Al and unavoidable impurities.

[0011] A method for preparing a high-strength and heat-resistant Al-Fe-Cr-Ti alloy comprises the following steps:

[0012] S1, fully mixing the components of the high-strength and heat-resistant aluminum alloy substrate;

[0013] S2, smelting the prepared raw materials at high temperature in a smelting furnace, adding a slag remover, deslagging and refining the liquid metal, and using a vacuum standing furnace degassing and argon degassing process to obtain liquid metal;

[0014] S3, atomizing the liquid metal in an inert atmosphere to form a particle jet, controlling the flow rate of the particle jet, and allowing the particle jet to be deposited on a substrate at a high speed, solidifying to form a large-sized heat-resistant aluminum alloy ingot material;

[0015] S4, finally, the spray-formed ingot is naturally cooled to 200°C to eliminate residual stress, and then taken out for air cooling;

[0016] S5, machining the spray-formed ingot into a round ingot of a specific size;

[0017] S6, extruding the processed ingot into a product with a desired cross-sectional size.

[0018] Preferably, in S2, the high-temperature smelting temperature is 700-800°C, and the holding time is 5-10 hours.

[0019] Preferably, in S2, the slag remover is a mixture of sodium chloride, potassium chloride and calcium chloride in a mass ratio of 4:3:1; the amount of the slag remover added is 0.2-0.3% of the mass of the molten aluminum liquid.

[0020] Preferably, in S2, the refining gas is argon Ar or nitrogen N2; the vacuum degree of the vacuum standing furnace is 10 -2 to 10 -3 Pa.

[0021] Preferably, in S3, argon is used as the inert gas, the liquid metal enters the atomization chamber through the nozzle, and high-speed argon is ejected from around the nozzle, impacting the liquid metal flow, causing it to split into fine particles, forming a particle jet stream; the injection molding process parameters are: liquid metal flow rate 10-50kg / min, argon flow rate 100-500m / s, gas pressure 0.2-0.8MPa, particle speed 200-600m / s, substrate rotation speed 50-300RPM, and substrate movement speed 0.1-10mm / s.

[0022] Preferably, in S3, the outer diameter of the large-size heat-resistant aluminum alloy ingot material is 50-500 mm, and more preferably, the outer diameter is 200-450 mm.

[0023] Preferably, in S5, the diameter of the round ingot of a specific size is 30-480 mm, more preferably 178-381 mm.

[0024] Preferably, in S6, the extrusion process parameters are: the head temperature of the round ingot is 430-470°C, the tail temperature is 420-460°C, the mold temperature is 430-470°C, the extrusion rod speed is 1.0-3.0 mm / s, and the extruded profile is cooled by any one of strong wind cooling, water mist cooling, spray cooling, and water cooling, and the cooling rate is greater than 180°C / min.

[0025] Further preferably, in S6, the extrusion process parameters are: the head temperature of the round ingot is 440-460°C, the tail temperature is 430-450°C, the mold temperature is 440-460°C, the extrusion rod speed is 1.5-2.0 mm / min, and the extruded profile is cooled by any one of strong wind cooling, water mist cooling, spray cooling, and water cooling treatment, and the cooling rate is greater than 200°C / min.

[0026] The high-strength and heat-resistant Al-Fe-Cr-Ti alloy obtained by the preparation method of the present invention has two characteristic phases, namely, an Fe-containing phase and an Fe-containing quasicrystal phase. The Fe-containing phase is uniformly and dispersedly distributed in the matrix, with an average size of 0.8-1.5 μm. At the same time, a nanometer-level uniformly and dispersed Fe-containing quasicrystal phase is found in the matrix, with an average size of 100-700 nm.

[0027] The invention discloses an application of a high-strength and heat-resistant Al-Fe-Cr-Ti alloy in lightweight and high-temperature structural materials for aviation and aerospace.

[0028] The present invention has the following beneficial effects:

[0029] The present invention designs a new alloy composition, Al-Fe-Cr-Ti-Co-RE, by controlling the contents of the alloying elements Fe, Cr, and Ti while simultaneously adding the alloying elements Co and RE. The ingot is prepared through a rapid solidification cooling method using spray deposition. The resulting product, combined with an extrusion process, exhibits excellent overall performance and maintains high mechanical properties when used at temperatures above 300°C. This significantly expands the application range of heat-resistant aluminum alloys and is widely used in lightweight, high-temperature materials for aviation and aerospace applications.

[0030] The heat-resistant aluminum alloy prepared by the present invention has excellent comprehensive properties, with a room temperature tensile strength exceeding 590 MPa, a yield strength exceeding 530 MPa, and an elongation exceeding 3.5%; a tensile strength exceeding 192 MPa, a yield strength exceeding 144 MPa, and an elongation exceeding 17.1% at a temperature of 400°C, and can be used as a lightweight high-temperature structural material for aviation and aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a SEM image of the high-strength heat-resistant aluminum alloy extruded product prepared in Example 1 of the present invention;

[0032] Figure 2 This is a TEM image of the high-strength heat-resistant aluminum alloy extruded product prepared in Example 1 of the present invention;

[0033] Figure 3 This is a SEM image of the high-strength heat-resistant aluminum alloy extruded product prepared in Comparative Example 1 of the present invention;

[0034] Figure 4 This is a TEM image of the high-strength and heat-resistant aluminum alloy extruded product prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to specific examples. The following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0036] Example 1

[0037] The raw material composition of the high-strength and heat-resistant Al-Fe-Cr-Ti alloy provided in this embodiment is shown in Table 1.

[0038] The alloy is prepared by the following method:

[0039] 1) The alloy is prepared according to the chemical composition ratio; the prepared metal material is smelted at a high temperature of 780°C in a smelting furnace for 5 hours; a certain amount of slag remover is added, the addition amount is 0.25% of the mass of the molten aluminum liquid, and the slag remover is a chloride salt refining agent, wherein the mixture ratio of sodium chloride, potassium chloride and calcium chloride is 4:3:1; the liquid metal is deslagging, the slag remover is evenly sprinkled on the surface of the molten aluminum liquid, and the aluminum liquid is gently stirred with a stirring tool to ensure that the slag remover and the aluminum liquid are fully in contact and impurities float up; the aluminum liquid is allowed to stand for 15 minutes to allow impurities and slag to accumulate on the surface; a slag removal tool, a slag removal rake, is used to gently scrape the slag and impurities on the surface out of the molten pool; argon (Ar) or nitrogen (N2) is used for degassing and refining, and the gas is introduced into the bottom of the aluminum liquid through a refining lance (or rotor). When the bubbles rise, they capture and carry away dissolved hydrogen and other impurities, and a vacuum standing furnace degassing (vacuum degree 0.005Pa) and argon degassing process are adopted.

[0040] 2) The liquid metal is then atomized in an inert gas atmosphere of argon, and the liquid aluminum alloy enters the atomization chamber through a nozzle. High-speed inert gas argon is ejected from around the nozzle, impacting the liquid metal flow, breaking it into fine particles and forming a particle jet. The spray forming process parameters are adjusted by adjusting the diameter of the metal pouring nozzle or the pressure of the liquid metal to control the metal flow rate to 30 kg / min, the inert gas flow rate to 300 m / s, and the gas pressure to 0.6 MPa. The particle velocity is 400 m / s to ensure sufficient cooling before the particles are deposited on the substrate. The substrate rotation speed is 150 RPM, and the substrate movement speed is 8 mm / s. Infrared sensing is used to control the size of the sprayed ingot and the flow rate of the particle jet. The particle jet is then deposited on the substrate at high speed, solidifying to form a heat-resistant aluminum alloy ingot material. The maximum outer diameter of the spray-formed ingot is 240 mm.

[0041] 3) Finally, the spray-formed ingot is naturally cooled to 200°C to eliminate residual stress and then taken out for air cooling.

[0042] 4) The spray-formed ingot is machined into a round ingot with a diameter of 228 mm.

[0043] 5) The processed ingot is extruded. The extrusion process is as follows: the head temperature of the round cast rod is 450°C, the tail temperature is 440°C, the mold temperature is 450°C, the extrusion rod speed is 1.8 mm / s, and the profile is spray-cooled after extrusion at a cooling rate of about 300°C / min.

[0044] 6) Finally, the product is extruded into a specific cross-section.

[0045] Example 1 is based on Al-Fe-Cr-Ti alloy, and optimizes the design of the addition amount and ratio of each alloy element Fe, Cr, and Ti. At the same time, the key elements Co and RE are added, and the addition amount of Co and RE elements is reasonably controlled. In the alloy design of this embodiment, the addition of Co content and RE content can extend the solidification time of the alloy, promote grain refinement and improve the mechanical properties of the alloy. The most important thing is that the addition of Co and RE can greatly promote the formation of Fe-containing quasicrystal phase. This embodiment obtains a structure of specific phase organization, which can still maintain good thermal stability above 150°C, which is beneficial to improving the high-temperature mechanical properties of the alloy. The spray-deposited ingot is extruded, and the process parameters during the extrusion process are controlled to obtain the best microstructure. The material has two characteristic phases, namely the Fe-containing phase and the Fe-containing quasicrystal phase; Figure 1 As shown in Figure 2, the Fe-containing phase is uniformly and dispersedly distributed in the matrix, with an average size of 0.8 μm; Figure 2 As shown, a uniform, dispersed Fe-containing quasi-crystalline phase with an average size of 100 nm was found within the matrix. This microstructure is conducive to achieving optimal mechanical properties. As shown in Table 2, the product obtained in Example 1 exhibits excellent overall performance, with room temperature tensile strength of 600 MPa, yield strength of 540 MPa, and elongation of 4.3%; and at 400°C, tensile strength of 200 MPa, yield strength of 150 MPa, and elongation of 18.0%.

[0046] Example 2 to Example 3

[0047] The raw material compositions of the high-strength and heat-resistant Al-Fe-Cr-Ti alloys provided in Examples 2 and 3 are shown in Table 1.

[0048] The difference between the preparation method of Example 2 and Example 1 is that:

[0049] In step 2), the outer diameter of the spray-formed blank is 50 mm.

[0050] In step 4), the spray-formed ingot is machined into a round ingot with a diameter of 30 mm.

[0051] In step 5), the extrusion process parameters are preferably: the head temperature of the round cast rod is 440°C, the tail temperature is 430°C, the mold temperature is 440°C, the extrusion rod speed is 1.5 mm / s, and the profile is cooled by strong wind after extrusion at a cooling rate of 200°C / min.

[0052] The Fe-containing phase is uniformly and dispersedly distributed in the matrix, with an average size of 1.0μm; at the same time, a nano-scale uniformly and dispersed Fe-containing quasi-crystalline phase is found in the matrix, with an average size of 600nm.

[0053] The difference between the preparation method of Example 3 and Example 1 is that:

[0054] In step 2), the outer diameter of the injection-molded blank is 500 mm.

[0055] In step 4), the spray-formed ingot is machined into a round ingot with a diameter of 480 mm.

[0056] In step 5), the extrusion process parameters are preferably: the head temperature of the round cast rod is 460°C, the tail temperature is 450°C, the mold temperature is 460°C, the extrusion rod speed is 2.0 mm / s, and the extruded profile is cooled by water mist at a cooling rate of 250°C / min.

[0057] The Fe-containing phase is uniformly and dispersedly distributed in the matrix, with an average size of 1.5μm; at the same time, a nano-scale uniformly and dispersed Fe-containing quasicrystal phase is found in the matrix, with an average size of 700nm.

[0058] In Examples 2 and 3, the key elements Co and RE are also added to the Al-Fe-Cr-Ti alloy, wherein the Co addition amount in Example 2 is 3.0 wt.%, and the RE addition amount is 0.5 wt.%; while the Co addition amount in Example 3 is 7.5 wt.%, and the RE addition amount is 2.5 wt.%. It can be seen from the mechanical properties tested in Table 2 that with the increase of the Co and RE element content, the room temperature and medium-high temperature mechanical properties of the alloy show a trend of first increasing and then decreasing, and the best comprehensive mechanical properties are achieved when the Co element content is 6.0 wt.% and the RE element content is 1.8 wt.%.

[0059] Example 4 to Example 5

[0060] The raw material compositions of the high-strength and heat-resistant Al-Fe-Cr-Ti alloys provided in Examples 4 and 5 are shown in Table 1. The preparation method of Example 4 is as follows:

[0061] 1) Prepare the materials according to the chemical composition ratio of the alloy; smelt the prepared metal materials in a smelting furnace at a high temperature of 700℃ and keep warm for 5 hours; add a certain amount of slag remover, the addition amount is 0.2% of the mass of the molten aluminum liquid, and the slag remover is a chloride salt refining agent, wherein the mixture ratio of sodium chloride, potassium chloride and calcium chloride is 4:3:1; slag the liquid metal, sprinkle the slag remover evenly on the surface of the molten aluminum liquid, use a stirring tool to gently stir the aluminum liquid to make the slag remover fully contact with the aluminum liquid and make the impurities float; let the aluminum liquid stand for 20 minutes to allow impurities and slag to accumulate on the surface; use a slag removal tool, a slag removal rake, to gently scrape the slag and impurities on the surface out of the molten pool; use argon (Ar) or nitrogen (N2) for degassing and refining, and introduce the gas into the bottom of the aluminum liquid through a refining spray gun (or rotor). When the bubbles rise, they capture and take away the dissolved hydrogen and other impurities, and use a vacuum standing furnace for degassing (vacuum degree 10 -2 Pa) and argon degassing process.

[0062] 2) The liquid metal is then atomized in an inert gas atmosphere of argon. The liquid aluminum alloy enters the atomization chamber through a nozzle. High-speed inert gas argon is ejected from around the nozzle, impacting the liquid metal flow, breaking it into fine particles and forming a particle jet. The injection molding process parameters are adjusted by adjusting the diameter of the metal pouring nozzle or the pressure of the liquid metal to control the metal flow rate to 10 kg / min, the inert gas flow rate to 100 m / s, and the gas pressure to 0.2 MPa. The particle velocity is 200 m / s to ensure that the particles are fully cooled before being deposited on the substrate. The substrate rotation speed is 50 RPM and the substrate movement speed is 0.1 mm / s. Infrared sensing is used to control the size of the injection ingot and the flow rate of the particle jet. The particle jet is then deposited on the substrate at high speed, solidifying to form a heat-resistant aluminum alloy ingot material. The maximum outer diameter of the injection-molded ingot is 200 mm.

[0063] 3) Finally, the spray-formed ingot is naturally cooled to 200°C to eliminate residual stress and then taken out for air cooling.

[0064] 4) The spray-formed ingot was machined into a round ingot with a diameter of 178 mm.

[0065] 5) The processed ingot is extruded. The extrusion process is as follows: the head temperature of the round cast rod is 430°C, the tail temperature is 420°C, the mold temperature is 430°C, the extrusion rod speed is 1.0 mm / s, and the profile is water mist cooled after extrusion at a cooling rate of about 250°C / min.

[0066] 6) Finally, the product is extruded into a specific cross-section.

[0067] The preparation method of Example 5 is as follows:

[0068] 1) Prepare the materials according to the chemical composition ratio of the alloy; smelt the prepared metal materials in a smelting furnace at a high temperature of 800℃ and keep warm for 10 hours; add a certain amount of slag remover, the addition amount is 0.3% of the mass of the molten aluminum liquid, and the slag remover is a chloride salt refining agent, wherein the mixture ratio of sodium chloride, potassium chloride and calcium chloride is 4:3:1; slag the liquid metal, sprinkle the slag remover evenly on the surface of the molten aluminum liquid, use a stirring tool to gently stir the aluminum liquid to make the slag remover fully contact with the aluminum liquid and make the impurities float; let the aluminum liquid stand for 18 minutes to allow impurities and slag to accumulate on the surface; use a slag removal tool, a slag removal rake, to gently scrape the slag and impurities on the surface out of the molten pool; use argon (Ar) or nitrogen (N2) for degassing and refining, and introduce the gas into the bottom of the aluminum liquid through a refining spray gun (or rotor). When the bubbles rise, they capture and take away the dissolved hydrogen and other impurities, and use a vacuum standing furnace for degassing (vacuum degree 10 -3 Pa) and argon degassing process.

[0069] 2) The liquid metal is then atomized in an inert gas atmosphere of argon. The liquid aluminum alloy enters the atomization chamber through a nozzle. High-speed inert gas argon is ejected from around the nozzle, impacting the liquid metal flow, breaking it into fine particles and forming a particle jet. The spray forming process parameters are adjusted by adjusting the diameter of the metal pouring nozzle or the pressure of the liquid metal to control the metal flow rate to 50 kg / min, the inert gas flow rate to 500 m / s, and the gas pressure to 0.8 MPa. The particle velocity is 600 m / s to ensure sufficient cooling before the particles are deposited on the substrate. The substrate rotation speed is 300 RPM, and the substrate movement speed is 10 mm / s. Infrared sensing is used to control the size of the sprayed ingot and the flow rate of the particle jet. The particle jet is then deposited on the substrate at high speed, solidifying to form a heat-resistant aluminum alloy ingot. The maximum outer diameter of the spray-formed ingot is 450 mm.

[0070] 3) Finally, the spray-formed ingot is naturally cooled to 200°C to eliminate residual stress and then taken out for air cooling.

[0071] 4) The spray-formed ingot was machined into a round ingot with a diameter of 381 mm.

[0072] 5) The processed ingot is extruded. The extrusion process is as follows: the head temperature of the round cast rod is 470°C, the tail temperature is 460°C, the mold temperature is 470°C, the extrusion rod speed is 3.0 mm / s, and the profile is water-cooled after extrusion at a cooling rate of about 400°C / min.

[0073] In Example 4, rare earth elements (RE) are added to an Al-Fe-Cr-Ti alloy. The rare earth elements can be added singly or in a mixture of two or more, with the total rare earth element addition being appropriately controlled to 1.8%. 3.0% of Co is also added. This alloy design also achieves a specific microstructure containing two characteristic phases: an Fe-containing phase and an Fe-containing quasicrystal phase. This phase maintains good thermal stability above 150°C, thereby improving the alloy's mechanical properties above 150°C.

[0074] In Example 5, the key element Co is added, along with the rare earth element RE. The rare earth elements can be added singly or in a mixture of two or more, with the total rare earth element addition controlled to 1.8%. This alloy design also yields a specific microstructure containing two characteristic phases: an Fe-containing phase and an Fe-containing quasicrystal phase. This phase maintains excellent thermal stability above 150°C, resulting in excellent overall performance, as shown in Table 2.

[0075] Example 6 to Example 11

[0076] The raw material compositions of the high-strength and heat-resistant Al-Fe-Cr-Ti alloys provided in Examples 6 to 11 are shown in Table 1. The preparation methods of Examples 6 to 11 are the same as those of Example 1.

[0077] In Examples 6 to 11, while ensuring the reasonable addition of the key element Co and rare earth elements, excellent comprehensive mechanical properties can also be obtained by adjusting the content and ratio of each element Fe, Cr, and Ti. The obtained mechanical properties are shown in Table 2.

[0078] Comparative Examples 1 to 7

[0079] The raw material compositions of the high-strength and heat-resistant aluminum alloy materials provided in Comparative Examples 1 to 7 are shown in Table 1. The preparation method of the alloy is the same as that of Example 1.

[0080] Comparative Example 1: Conventional Al-Fe-Cr-Ti alloy, without adding element Co and rare earth element RE, the spray-deposited ingot is extruded. Figure 3 As shown in Figure 2, the Fe-containing phase in the matrix is unevenly distributed and contains coarse aggregates with a size greater than 15 μm. Figure 4 As shown in the TEM image, no Fe-containing quasicrystal phase was found, but micron-sized Fe-containing phases exceeding 5 μm were present. This coarse phase structure is detrimental to the mechanical properties of the alloy. The mechanical properties of the alloy significantly decrease above 150°C, and the thermal stability deteriorates at high temperatures.

[0081] The addition of key alloying elements Co and RE needs to be controlled within the scope of the present invention, that is, Co

[0082] 3.0-7.5wt.%, RE 0.5-2.5wt.%, and the two elements are added at the same time.

[0083] In comparative example 2, adding Co alone, or in comparative example 3, adding RE alone, neither effectively promotes the formation of Fe-containing quasi-crystalline phase, and the matrix contains coarse aggregated phases with a size greater than 15 μm; the room temperature and medium-high temperature mechanical properties of the material are reduced.

[0084] In Comparative Examples 4 and 5, although the addition amount of rare earth RE is within the scope of the present invention, the addition amount of element Co is too high (8.5 wt.%) or too low (2.0 wt.%), and the ideal phase structure cannot be achieved. Too high Co is prone to aggregation, and too low Co cannot promote the formation of Fe-containing quasi-crystalline phase well. In both states, the matrix contains coarse aggregated phases with a size greater than 15 μm; the room temperature and medium- and high-temperature mechanical properties of the material are reduced.

[0085] In Comparative Examples 6 and 7, although the addition amount of element Co is within the scope of the present invention, the addition amount of rare earth RE is too high by 3.0 wt.% or too low by 0.3 wt.%, and the ideal phase structure cannot be achieved. The rare earth RE is too high and easy to aggregate, and the rare earth RE is too low and cannot promote the formation of Fe-containing quasi-crystalline phase. In both states, the matrix contains coarse aggregated phases with a size greater than 15 μm; the room temperature and medium and high temperature mechanical properties of the material are reduced.

[0086] Comparative Example 8

[0087] The only difference between this comparative example and Example 1 is that: Steps 2) to 6) are replaced by: smelting and casting to obtain aluminum rods; homogenizing the aluminum rods, heating them from room temperature to 580°C at a heating rate of 100°C / h, keeping them warm for 5 hours, then transferring them from the homogenizing furnace to the cooling furnace for less than 10 minutes, using water cooling at a cooling rate of 300°C / h, cooling to 100°C, and air cooling; peeling the aluminum rods to form round ingots with a diameter of 228mm. The processed ingots are extruded, and the extrusion process is as follows: the temperature of the round rod head is 450°C, the temperature of the tail is 440°C, the mold temperature is 450°C, the extrusion rod speed is 1.8mm / s, and the profile is spray-cooled after extrusion at a cooling rate of about 300°C / min. Finally, the product with a specific cross-section is extruded.

[0088] In Comparative Example 8, conventional solidification cooling process is adopted, which is not conducive to the improvement and enhancement of the performance of the aluminum alloy. The mechanical properties at room temperature and medium and high temperatures are reduced, no Fe-containing quasicrystal phase is found in the microstructure, and coarse aggregated phase is contained.

[0089] It can be seen from Table 2 that, for the comparative alloys, the room temperature tensile strength does not exceed 469 MPa, the yield strength does not exceed 394 MPa, and the elongation does not exceed 3.8%; at 400°C, the tensile strength does not exceed 165 MPa, the yield strength does not exceed 94 MPa, and the elongation does not exceed 19.0%.

[0090] Table 1 Composition of the alloy raw materials corresponding to Examples 1 to 11 and Comparative Examples 1 to 8 (in percentage by mass)

[0091]

[0092] The mechanical properties of the aluminum alloy products of Examples 1 to 11 and Comparative Examples 1 to 8 were tested in accordance with GB / T 16865-2013. The results are shown in Table 2.

[0093] Table 2 Mechanical properties test results of products corresponding to Examples 1 to 11 and Comparative Examples 1 to 8

[0094]

[0095]

[0096]

[0097] It should be understood that in order to streamline the present disclosure and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0098] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength and heat-resistant Al-Fe-Cr-Ti alloy, characterized in that: The high-strength and heat-resistant aluminum alloy substrate comprises the following components: Fe 4.0-7.0 wt.%, Cr 2.5-6.0 wt.%, Ti 2.5-6.0 wt.%, Co 3.0-7.5 wt.%, rare earth La, Ce, Nd, and Y in a total amount of 0.5-2.5 wt.%, and the balance being Al and unavoidable impurities; The preparation method comprises the following steps: S1, fully mixing the components of the high-strength and heat-resistant aluminum alloy substrate; S2, smelting the prepared raw materials at high temperature in a smelting furnace, adding a slag remover, deslagging and refining the liquid metal, and using a vacuum standing furnace degassing and argon degassing process to obtain liquid metal; S3, atomizing the liquid metal in an inert atmosphere to form a particle jet, controlling the flow rate of the particle jet, and allowing the particle jet to be deposited on a substrate at a high speed, solidifying to form a large-sized heat-resistant aluminum alloy ingot material; S4, finally, the spray-formed ingot is naturally cooled to 200°C to eliminate residual stress, and then taken out for air cooling; S5, machining the spray-formed ingot into a round ingot of a specific size; S6, extruding the processed ingot into a product with a desired cross-sectional size; In S3, argon is used as the inert gas. Liquid metal enters the atomization chamber through a nozzle. High-speed argon is ejected from around the nozzle, impacting the liquid metal flow, causing it to break into fine particles and forming a particle jet. The spray forming process parameters are: liquid metal flow rate 10-50 kg / min, argon flow rate 100-500 m / s, gas pressure 0.2-0.8 MPa, particle velocity 200-600 m / s, substrate rotation speed 50-300 RPM, and substrate movement speed 0.1-10 mm / s. In S6, the extrusion process parameters are: the head temperature of the round ingot is 430-470°C, the tail temperature is 420-460°C, the mold temperature is 430-470°C, the extrusion rod speed is 1.0-3.0 mm / s, and the extruded profile is cooled by any one of strong wind cooling, water mist cooling, spray cooling, and water cooling after extrusion, with a cooling rate of >180°C / min; Two characteristic phases exist in high-strength and heat-resistant aluminum alloys: an Fe-containing phase and an Fe-containing quasicrystal phase. The Fe-containing phase is uniformly and dispersedly distributed in the matrix, with an average size of 0.8-1.5 μm. Meanwhile, nanoscale uniformly and dispersed Fe-containing quasicrystals are found in the matrix, with an average size of 100-700 nm. The room temperature tensile strength of the heat-resistant aluminum alloy exceeds 590MPa, the yield strength exceeds 530MPa, and the elongation exceeds 3.5%; at 400°C, the tensile strength exceeds 192MPa, the yield strength exceeds 144MPa, and the elongation exceeds 17.1%.

2. The preparation method according to claim 1, characterized in that In S2, the high temperature melting temperature is 700-800°C and the holding time is 5-10h.

3. The preparation method according to claim 2, characterized in that In S2, the slag remover is a mixture of sodium chloride, potassium chloride and calcium chloride in a mass ratio of 4:3:1; the amount of the slag remover added is 0.2-0.3% of the mass of the molten aluminum water.

4. The preparation method according to claim 2, characterized in that In S2, the refining gas is argon Ar or nitrogen N2; the vacuum degree of the vacuum standing furnace is 10 -2 to 10 -3 Pa.

5. The preparation method according to claim 2, characterized in that In S3, the outer diameter of the large-sized heat-resistant aluminum alloy ingot material is 50-500mm; in S5, the diameter of the round ingot of specific size is 30-480mm.

6. Use of a high-strength and heat-resistant Al-Fe-Cr-Ti alloy obtained by the preparation method according to any one of claims 1 to 5 in lightweight and high-temperature structural materials for aviation and aerospace.

Images