High-strength heat-resistant aluminum alloy and preparation method thereof

Abstract

The invention relates to a high-strength heat-resistant aluminum alloy and a preparation method thereof, and belongs to the technical field of additive manufacturing aluminum alloys. The high-strength heat-resistant aluminum alloy comprises 3.5%-5.5% of Mn; 0.66% to 0.75% of Sc; 1.5% to 2.5% of Ni; 0.5% to 0.9% of Fe; 0.81% to 1.2% of La; 1.5% to 2.0% of Ce; zr: 0.25% to 0.45%; 0.1% to 0.5% of Nd; al: the balance; wherein the total weight of Mn, Sc, Ni, Fe, La, Ce, Zr and Nd is 10.5%-12%. Through performance tests, at room temperature, the tensile strength and the yield strength of the high-strength heat-resistant aluminum alloy reach 680 MPa and 570 MPa respectively; when the temperature is 250 DEG C, the tensile strength exceeds 430 MPa; and at 300 DEG C, the tensile strength reaches 320 MPa or above.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing of aluminum alloys, and in particular to a high-strength heat-resistant aluminum alloy and a preparation method thereof. Background Art

[0002] Additive manufacturing has good designability and can meet the needs of rapid and precise forming of complex, thin-walled, hollow parts and components, and has broad application prospects in fields such as aerospace. Aluminum alloys have good specific strength and specific stiffness. As an important lightweight structural material, they have also become the preferred material type for additive manufacturing of lightweight structural parts. However, at this stage, there are relatively few materials for additive manufacturing of aluminum alloys. The room temperature strength of traditional AlSiMg alloys after additive manufacturing is only 400-500MPa, and the room temperature strength after stress relief annealing treatment drops to 200-300MPa, which cannot meet the needs of high-load bearing component manufacturing. At the same time, the high temperature strength of this type of alloy is low, and the tensile strength at 200°C is less than 200MPa, which cannot meet the needs of high-temperature service environments.

[0003] AlMgSc alloy is a high-strength aluminum alloy manufactured using additive manufacturing. Its room-temperature tensile strength can reach over 500 MPa, but its high-temperature performance is very poor. At 250°C, the alloy's tensile strength is approximately 130 MPa, and at 300°C, the tensile strength is only around 70 MPa. This indicates that the alloy cannot meet the requirements of high-temperature service environments.

[0004] AlMnSc alloy has good high-temperature mechanical properties, and its room temperature tensile strength is comparable to that of AlMgSc alloy, and the tensile strength at 250°C can usually reach 250MPa. Through alloying, the room temperature tensile strength of the alloy of some components is increased to 600MPa; at 300°C, the tensile strength and yield strength of the alloy can also reach 220MPa and 200MPa or more. However, with the increasing demand for lightweight and high-performance development in aerospace, the pursuit of higher strength and higher resistance to high-temperature softening is the focus of additive manufacturing of high-strength and heat-resistant aluminum alloys. In order to pursue higher strength (room temperature and / or high temperature), the existing method is mainly to increase the Mn element content, but with the increase of Mn element content, the additive manufacturing alloy has a significant tendency to hot cracking, which is difficult to meet the process requirements of additive manufacturing. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a high-strength heat-resistant aluminum alloy and a preparation method thereof, so as to improve the strength of the aluminum alloy and ensure that there is no cracking during the printing process.

[0006] On the one hand, the present invention provides a high-strength and heat-resistant aluminum alloy, in which the chemical elements include, by weight percentage, Mn: 3.5% to 5.5%; Sc: 0.66% to 0.75%; Ni: 1.5% to 2.5%; Fe: 0.5% to 0.9%; La: 0.81% to 1.2%; Ce: 1.5% to 2.0%; Zr: 0.25% to 0.45%; Nd: 0.1% to 0.5%; Al: balance; wherein the total weight of Mn, Sc, Ni, Fe, La, Ce, Zr and Nd is 10.5% to 12%.

[0007] Furthermore, in terms of weight percentage, the chemical elements of the high-strength heat-resistant aluminum alloy include Mn: 3.7% to 5.2%; Sc: 0.66% to 0.75%; Ni: 1.5% to 2.5%; Fe: 0.5% to 0.9%; La: 0.81% to 1.2%; Ce: 1.5% to 2.0%; Zr: 0.25% to 0.45%; Nd: 0.1% to 0.5%; and Al: balance.

[0008] Furthermore, at room temperature, the tensile strength is above 680 MPa and the yield strength is above 570 MPa.

[0009] Furthermore, at a temperature of 250° C., the tensile strength is above 430 MPa.

[0010] Furthermore, at a temperature of 300° C., the tensile strength is above 320 MPa.

[0011] Furthermore, the high-strength and heat-resistant aluminum alloy comprises an aluminum matrix and nano-scale intermetallic compounds dispersed in the aluminum matrix.

[0012] On the other hand, the present invention provides a method for preparing a high-strength heat-resistant aluminum alloy, which is prepared by combining gas atomization screening and additive manufacturing.

[0013] Furthermore, the preparation method comprises the following steps:

[0014] S1: Powder preparation: aluminum ingots, magnesium ingots, aluminum-based master alloy ingots or alloy prefabricated ingots are used as alloy raw materials. They are smelted in a vacuum atomization furnace under inert atmosphere protection. The metal liquid is crushed by an inert gas flow with a pressure of 1 to 5 MPa to prepare different types of alloy powders.

[0015] S2: powder processing, screening, mixing and drying the obtained alloy powder;

[0016] After sieving, the particle size of the alloy powder is ≤200μm;

[0017] S3: Additive manufacturing, using laser powder bed fusion technology to perform additive manufacturing on the processed alloy powder; the additive manufacturing process uses argon protection, the oxygen content of the atmosphere is controlled to be less than 150ppm, and the substrate preheating temperature is 150-300℃;

[0018] S4: High-strength and heat-resistant aluminum alloy is produced after heat treatment.

[0019] Furthermore, in step S3, a strip scanning strategy is adopted, the laser power is 265-295 W, the scanning rate is 1600-1800 mm / s, the powder layer thickness is 20-60 μm, and the overlap spacing is 0.13-0.2 mm.

[0020] Furthermore, in step S4, the heating temperature of the heat treatment is 310-360° C., and the holding time is 7-12 hours.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The present invention ensures the adaptability of the additive manufacturing forming process by appropriately reducing the Mn element content, while taking into account the mechanical properties at room temperature and high temperature. By adding the Fe element, the AlMnFe quasi-crystalline phase is formed in the structure; by adding Ni and increasing elements such as La and Ce, intermetallic compounds with good thermal stability are formed, further improving the mechanical properties at room temperature and high temperature. After performance testing, at room temperature, the tensile strength and yield strength reached 680MPa and 570MPa respectively; at 250°C, the tensile strength exceeded 430MPa; at 300°C, the tensile strength reached more than 320MPa;

[0023] 2. The present invention does not generate cracks during the additive manufacturing process through the mutual coordination of alloy elements and the content of each element. The resulting aluminum alloy not only has high strength at room temperature, but also has high strength at high temperatures.

[0024] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0026] Figure 1 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 1;

[0027] Figure 2 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 2;

[0028] Figure 3 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 3;

[0029] Figure 4 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 4;

[0030] Figure 5 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 5;

[0031] Figure 6 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 6;

[0032] Figure 7 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 7;

[0033] Figure 8 This is a metallographic photograph of the high-strength and heat-resistant aluminum alloy obtained in Example 8;

[0034] Figure 9 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 1;

[0035] Figure 10 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 2;

[0036] Figure 11 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 3;

[0037] Figure 12 This is a physical picture of the aluminum alloy obtained in Comparative Example 4 (with cracks);

[0038] Figure 13 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 5;

[0039] Figure 14 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 6;

[0040] Figure 15 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 7;

[0041] Figure 16 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 8;

[0042] Figure 17 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 9;

[0043] Figure 18 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 10;

[0044] Figure 19 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 11. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0046] Additive manufacturing has broad application prospects in fields such as aerospace. As a traditional lightweight structural material, aluminum alloy has become an indispensable and important material for the preparation of lightweight structural parts for additive manufacturing. The development of high-strength and heat-resistant aluminum alloys suitable for additive manufacturing is a prerequisite for meeting the lightweight design and integrated manufacturing of lightweight, high-load-bearing, heat-resistant, and complex-shaped parts for additive manufacturing. Although the Al-Mn-Sc alloy system has a certain heat-resistant foundation, the tensile strength at 250°C is usually about 250MPa, which still cannot meet the needs of higher temperature or higher load service conditions. Further increasing the Mn content to more than 6%, the solid-liquid phase temperature difference of the alloy is larger, the adaptability of the additive manufacturing forming process is worse, and it cannot meet the needs of the additive manufacturing process.

[0047] Therefore, the present invention provides a high-strength heat-resistant aluminum alloy, which, in terms of weight percentage, includes chemical elements such as Mn: 3.5% to 5.5%; Sc: 0.66% to 0.75%; Ni: 1.5% to 2.5%; Fe: 0.5% to 0.9%; La: 0.81% to 1.2%; Ce: 1.5% to 2.0%; Zr: 0.25% to 0.45%; Nd: 0.1% to 0.5%; and Al: the balance; wherein the total weight of Mn, Sc, Ni, Fe, La, Ce, Zr, and Nd is 10.5% to 12%.

[0048] Compared with the existing technology, the present invention ensures the adaptability of the additive manufacturing forming process by appropriately optimizing the Mn element content, while taking into account the mechanical properties at room temperature and high temperature. By adding the Fe element, the AlMnFe quasi-crystalline phase is formed in the structure; by adding Ni and increasing elements such as La and Ce, intermetallic compounds with good thermal stability are formed, further improving the mechanical properties at room temperature and high temperature. After performance testing, at room temperature, the tensile strength and yield strength reached 680MPa and 570MPa respectively; at 250°C, the tensile strength exceeded 430MPa; at 300°C, the tensile strength reached more than 320MPa.

[0049] It should be noted that the elements in the present invention function as follows:

[0050] Mn: Manganese, as the main alloying element, ensures the adaptability of the forming process and the performance foundation of the high-strength and heat-resistant aluminum alloy. On the one hand, the addition of 3.5% to 5.5% of Mn elements makes the solid-liquidus temperature difference of the alloy within a controllable range, ensuring better adaptability to the additive manufacturing process. On the other hand, Mn and Al have a large lattice mismatch strain, ensuring that a certain amount of Mn can obtain a good solid solution strengthening effect. In addition, the thermal diffusion coefficient of Mn in the Al matrix is low, which makes the precipitation of Mn elements slow during the subsequent heat treatment process. A longer heat treatment is required to ensure sufficient precipitation, which helps to obtain better room temperature and high temperature strength.

[0051] Sc: Scandium is a precipitation strengthening element in the alloy, which helps to control the grain morphology and refine the grain size, providing a guarantee for improving the mechanical properties at room temperature and high temperature.

[0052] Zr: Zirconium can form Al3Zr with Al and has L12 structure. This phase has good thermal stability. When Zr and Sc exist at the same time, Zr atoms will partially replace Sc atoms in Al3Sc intermetallic compound to form Al3(Sc 1-x ,Zr x ) pseudo binary phase, which helps to reduce the amount of Sc element added and reduce material cost. However, if the zirconium content is too high, it will reduce the Al3(Sc 1-x ,Zr x ) The stability of the pseudo-binary phase is not conducive to obtaining a good precipitation strengthening effect.

[0053] It should be noted that in the present invention, the addition of element Fe can form the quasi-crystalline phase AlMnFe, and the addition of Ni, La and Ce can form Al3Ni, Al 11 La3、Al 11 Ce3 heat-resistant intermetallic compounds hinder dislocation migration and exert an Orowan strengthening effect. These intermetallic compounds also have high melting points and excellent thermal stability, effectively inhibiting microstructure coarsening during heat treatment and at high temperatures, helping to ensure the room-temperature and high-temperature strength of the resulting additively manufactured aluminum alloy. To ensure forming process performance, reduce hot cracking tendencies, and balance cost and performance improvements, the addition levels are as follows: Fe: 0.5% to 0.9%; Ni: 1.5% to 2.5%; La: 0.81% to 1.2%; and Ce: 1.5% to 2.0%.

[0054] Nd element helps to form nano-Al3Nd and Al 11 Nd3 intermetallic compound can enhance the grain boundary strength at high temperature and reduce the grain boundary softening under high temperature conditions.

[0055] It should be noted that the present invention does not include the element Mg. Due to its high activity, Mg is prone to burnout and oxidation during the forming process, resulting in increased oxide content in the structure, which is detrimental to forming and structural integrity. In particular, higher Mg content increases the degree of burnout and makes the alloy more susceptible to cracking. Furthermore, Mg has a high diffusion rate in the Al matrix, making it difficult to form a thermally stable second phase, and thus has no significant effect on improving high-temperature strength.

[0056] Specifically, in terms of weight percentage, the chemical elements of the high-strength heat-resistant aluminum alloy include Mn: 3.7% to 5.2%; Sc: 0.66% to 0.75%; Ni: 1.5% to 2.5%; Fe: 0.5% to 0.9%; La: 0.81% to 1.2%; Ce: 1.5% to 2.0%; Zr: 0.25% to 0.45%; Nd: 0.1% to 0.5%; and Al: the balance.

[0057] The present invention provides a method for preparing a high-strength heat-resistant aluminum alloy, which is prepared by combining gas atomization screening and additive manufacturing, and includes the following steps:

[0058] S1: Powder preparation: aluminum ingots, magnesium ingots, aluminum-based master alloy ingots or alloy prefabricated ingots are used as alloy raw materials. They are smelted in a vacuum atomization furnace under inert atmosphere protection. The metal liquid is crushed by an inert gas flow with a pressure of 1 to 5 MPa to prepare different types of alloy powders.

[0059] S2: powder processing, screening, mixing and drying the obtained alloy powder;

[0060] S3: Additive manufacturing, using laser powder bed fusion technology to perform additive manufacturing on the processed alloy powder;

[0061] S4: High-strength and heat-resistant aluminum alloy is produced after heat treatment.

[0062] Compared to existing technologies, this invention utilizes a combination of alloy components, gas atomization screening, and additive manufacturing to produce a high-strength aluminum alloy with a dense internal structure characterized by layered, fish-scale-like melt pools. The alloy is free of defects such as cracks and pores. Performance testing has shown that at room temperature, the tensile strength and yield strength reach 680 MPa and 570 MPa, respectively; at 250°C, the tensile strength exceeds 430 MPa; and at 300°C, the tensile strength exceeds 320 MPa.

[0063] It should be noted that aluminum ingots, magnesium ingots, aluminum-based master alloy ingots, or alloy prefabricated ingots are used as raw materials. Smelting is carried out in a vacuum atomization furnace under an inert atmosphere. High-pressure inert gas is used to break up the molten metal to produce the matrix alloy powder. The alloy powder is then cooled in the inert atmosphere.

[0064] Specifically, after screening, the particle size of the alloy powder is ≤200 μm.

[0065] Preferably, after screening, the particle size of the alloy powder is ≤75 μm.

[0066] It should be noted that if the alloy powder particle size is too large, the power required for melting with a high-energy laser beam or electron beam, for example, will be higher, which can easily cause burnout or oxidation of the alloying elements. Furthermore, excessively large particle size leads to high surface roughness during the forming process, which is detrimental to ensuring dimensional accuracy and surface quality. To ensure the quality and high-temperature performance of high-strength, heat-resistant aluminum alloys, the particle size of the alloy powder should be controlled to no more than 200 μm, preferably below 75 μm.

[0067] Specifically, the sieved alloy powder is mixed at a rotation speed of 1 r / min to 15 r / min for a duration of 10 min to 60 min.

[0068] It should be noted that the aforementioned speed and duration effectively achieve powder mixing, resulting in uniform particle size and composition, without significant agglomeration. If the speed is too slow, sufficient mixing is inadequate; if the speed is too high, friction between the alloy powders increases, easily leading to surface oxidation. If the duration is too short, the mixing effect is insufficient; if the duration is too long, static electricity accumulates on the powder surface, easily causing powder agglomeration.

[0069] Specifically, during the drying process, the mixed powder is placed on a tray and spread flat with a thickness of no more than 2 cm, and then placed in an explosion-proof drying oven and dried at 60° C. to 150° C. for 1 to 10 hours, and then cooled in the oven.

[0070] It should be noted that drying facilitates subsequent additive manufacturing and ensures the strength and quality of the resulting aluminum alloy. If the drying temperature is too low or the drying duration is too short, it will not effectively remove surface adsorbed moisture or oxygen. If the temperature is too high or the drying duration is too long, the alloy powder will oxidize more severely, resulting in relatively poor quality of the resulting aluminum alloy.

[0071] Specifically, in step S3, a strip scanning strategy is adopted, the laser power is 265-295 W, the scanning rate is 1600-1800 mm / s, the powder layer thickness is 20-60 μm, and the overlap spacing is 0.13-0.2 mm.

[0072] Specifically, the additive manufacturing process uses argon gas for protection, controls the oxygen content of the atmosphere to be less than 150 ppm, and preheats the substrate to a temperature of 150 to 300°C.

[0073] It should be noted that the parameters of the additive manufacturing process are closely related to the room temperature properties of the final aluminum alloy. When the laser power is too large, the scanning rate is too low, the powder layer thickness and the overlap spacing are too small, the volume energy density will be too high, and the low-boiling point elements in the melt will easily evaporate, resulting in the formation of circular holes in the structure; conversely, when the volume energy density is too small (the laser power is too low, the scanning speed is too high, or the powder layer thickness and the overlap spacing are too large), the input energy is not enough to completely remelt the alloy powder within the unit volume, resulting in defects such as irregular holes and unmelted powder.

[0074] In the present invention, the laser power may be 265W, 270W, 275W, 280W, 285W, 290W or 295W.

[0075] In the present invention, the scanning rate may be 1600 mm / s, 1650 mm / s, 1700 mm / s, 1750 mm / s or 1800 mm / s.

[0076] In the present invention, the thickness of the powder layer may be 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm or 60 μm.

[0077] In addition, in order to reduce oxidation and burning during the additive manufacturing process, inert gas (argon) protection is adopted, and the oxygen content in the forming chamber is ensured to be less than 150ppm. Since the alloy composition does not contain low-melting-point alloying elements such as Mg and Zn, the oxygen content in the forming chamber can be controlled below 150ppm. Compared with the forming chamber oxygen content of AlMgSc or Mg-containing AlMnSc alloys, which is usually required to be below 100ppm, the oxygen content control range of the present invention can be appropriately relaxed, which helps to shorten the air replacement time in the forming chamber, reduce argon consumption, and reduce production costs. However, excessively high oxygen content will still lead to severe oxidation and burning, destroy the continuity and integrity of the organization, and ultimately lead to a decrease in mechanical properties.

[0078] Substrate preheating can effectively control the cooling rate of the melt during the forming process, inhibit the alloy's cracking tendency, and optimize the grain size and morphology distribution. However, excessively high preheating temperatures can reduce the solid solution strengthening effect and, at the same time, reduce the amount of precipitated strengthening phases after heat treatment, reducing the precipitation strengthening effect. Excessively low preheating temperatures can lead to high cooling rates and large temperature gradients, making it easy for the structure to accumulate high residual stresses and exhibit a tendency to hot cracking. Therefore, considering the high content of alloying elements, in order to effectively inhibit the hot cracking tendency and ensure mechanical properties, the lower limit of the preheating temperature is appropriately increased, and the preheating temperature is selected to be 150-300°C.

[0079] Specifically, the heating temperature of the heat treatment is 310-360° C., and the holding time is 7-12 hours.

[0080] It should be noted that the present invention controls the heat treatment temperature to 310-360°C and the holding time to 7-12 hours, which facilitates the sufficient precipitation of intermetallic compounds such as Al3(Sc,Zr), Al3Zr, and Al3Ni in the aluminum alloy, ensuring that the volume fraction of the intermetallic compounds is greater than 15%. If the temperature is too low or the holding time is too short, the sufficient precipitation of the precipitation strengthening phase cannot be guaranteed. If the temperature is too high or the holding time is too long, the precipitate phase will cause unnecessary coarsening and growth, weakening the precipitation strengthening effect.

[0081] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.

[0082] Example 1

[0083] The preparation process of high-strength heat-resistant aluminum alloy is as follows:

[0084] S1: Powder preparation: alloy raw materials aluminum ingot, magnesium ingot, and aluminum-based master alloy ingot are weighed in proportion, placed in a crucible for melting, and the molten alloy liquid is crushed using nitrogen to prepare alloy powder, which is then cooled in an inert atmosphere;

[0085] S2: Powder processing: the alloy powder is sieved to obtain alloy powder of ≤60μm, and then the alloy powder is added to the mixer for mixing at a speed of 10r / min for 30min; the mixed alloy powder is placed on a tray and spread flatly with a thickness of 1.5cm, and then placed in an explosion-proof drying oven for drying at 120℃ for 1.5h, and cooled with the furnace;

[0086] S3: Additive manufacturing, using laser powder bed fusion equipment, adopting a strip scanning strategy, laser power 265W, scanning rate 1600mm / s, powder layer thickness 40μm, overlap spacing 0.13mm; argon protection is used during the forming process, and the oxygen content of the atmosphere is controlled at 120ppm; the substrate is preheated to 200℃ during the forming process and removed after cooling;

[0087] S4: The sample is heat treated in a heating furnace at a holding temperature of 310°C for 9 hours, and then cooled in the furnace to obtain a high-strength heat-resistant aluminum alloy.

[0088] Examples 2-4, Comparative Examples 1-3

[0089] The difference between Examples 2-4 and Comparative Examples 1-3 and Example 1 lies in the alloy composition ratio, as shown in Table 1.

[0090] Table 1 Different parameters of Examples 1-4 and Comparative Examples 1-3 (unit: wt%)

[0091]

[0092] *“-” in Table 1 means no addition.

[0093] Comparative Examples 4-5

[0094] The difference between Comparative Examples 4-5 and Example 1 lies in the different alloy compositions, as shown in Table 2.

[0095] Table 2 Different parameters of comparative examples 4-5 (unit: wt%)

[0096]

[0097] *“-” in Table 2 means no addition.

[0098] Examples 5-8, Comparative Examples 6-11

[0099] The difference between Examples 5-8 and Comparative Examples 6-11 and Example 1 lies in the different preparation methods, as shown in Table 3.

[0100] Table 3 Different parameters of Examples 5-8, Comparative Examples 6-11 and Example 1

[0101] Group Laser power / W Scanning rate mm / s Preheating temperature / ℃ Heat treatment Example 1 265 1600 200 310℃-9h Example 5 275 1700 250 310℃-9h Example 6 295 1800 300 310℃-9h Example 7 265 1600 150 310℃-12h Example 8 265 1600 250 330℃-7h Comparative Example 6 215 1600 250 310℃-9h Comparative Example 7 305 1600 250 310℃-9h Comparative Example 8 265 1900 250 310℃-9h Comparative Example 9 265 1400 250 310℃-9h Comparative Example 10 265 1600 Room temperature 310℃-9h Comparative Example 11 265 1600 350 310℃-9h

[0102] Performance testing

[0103] The above Examples 1-8 and Comparative Examples 1-11 were subjected to performance testing. The microstructure of the materials was observed and the tensile properties at room temperature and high temperature (250°C, 300°C) were tested in accordance with GB / T 3246.1-2012, HB5143-1996, and HB5195-1996, respectively. The test results are shown in Table 4, Table 5, and Table 6, respectively.

[0104] Table 4 Performance test results (room temperature)

[0105]

[0106]

[0107] Table 5 Performance test results (250℃)

[0108]

[0109]

[0110] Table 6 Performance test results (300℃)

[0111] Group Tensile strength / MPa Yield strength / MPa Remark Example 1 323 279 Example 2 337 295 Example 3 329 280 Example 4 358 325 Example 5 342 289 Example 6 335 284 Example 7 351 310 Example 8 336 291 Comparative Example 1 235 203 Comparative Example 2 - - Print cracking Comparative Example 3 240 208 Comparative Example 4 - - Print cracking Comparative Example 5 211 187 Comparative Example 6 268 241 Comparative Example 7 286 259 Comparative Example 8 306 270 Comparative Example 9 281 246 Comparative Example 10 - - Print cracking Comparative Example 11 283 258

[0112] Combined with Examples 1-8 and Comparative Examples 1-11 and Tables 4-6 and Figure 1-19It can be seen that when using the compositions and proportions provided in Examples 1-8, the coordinated combination of elements such as Mn, Sc, Fe, and Ni, La, and Ce results in high room temperature and high temperature strength. At room temperature, the resulting aluminum alloy has a tensile strength of 680-689 MPa and a yield strength of 570-580 MPa. At 250°C, the resulting aluminum alloy has a tensile strength of 435-455 MPa and a yield strength of 373-394 MPa. At 300°C, the resulting aluminum alloy has a tensile strength of 323-358 MPa and a yield strength of 279-325 MPa, with no internal cracks. The high-strength, heat-resistant aluminum alloy comprises an aluminum matrix with nanoscale intermetallic compounds dispersed within it, with the volume fraction of the intermetallic compounds exceeding 15%.

[0113] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A high-strength heat-resistant aluminum alloy, characterized in that: In terms of weight percentage, the chemical elements include Mn: 3.5% to 5.5%; Sc: 0.66% ~ 0.75%; Ni: 1.5% ~ 2.5%; Fe: 0.5%~0.9%; La: 0.81% to 1.2%; Ce: 1.5% to 2.0%; Zr: 0.25% to 0.45%; Nd: 0.1% to 0.5%; Al: balance; the total weight of Mn, Sc, Ni, Fe, La, Ce, Zr and Nd is 10.5% to 12%.

2. The high-strength heat-resistant aluminum alloy according to claim 1, characterized in that: According to weight percentage, the chemical elements of the high-strength heat-resistant aluminum alloy include Mn: 3.7% to 5.2%; Sc: 0.66% to 0.75%; Ni: 1.5% to 2.5%; Fe: 0.5%~0.9%; La: 0.81% ~ 1.2%; Ce: 1.5% ~ 2.0%; Zr: 0.25%~0.45%; Nd: 0.1%~0.5%; Al: balance.

3. The high-strength heat-resistant aluminum alloy according to claim 1 or 2, characterized in that: At room temperature, the tensile strength is above 680MPa and the yield strength is above 570MPa.

4. The high-strength heat-resistant aluminum alloy according to claim 1 or 2, characterized in that: At a temperature of 250°C, the tensile strength is above 430 MPa.

5. The high-strength heat-resistant aluminum alloy according to claim 1 or 2, characterized in that: At a temperature of 300°C, the tensile strength is above 320 MPa.

6. The high-strength heat-resistant aluminum alloy according to claim 1 or 2, characterized in that: The high-strength and heat-resistant aluminum alloy comprises an aluminum matrix and nano-scale intermetallic compounds dispersed in the aluminum matrix.

7. A method for preparing the high-strength heat-resistant aluminum alloy according to any one of claims 1 to 6, characterized in that: The preparation was carried out by combining aerosol screening and additive manufacturing.

8. The method for preparing the high-strength heat-resistant aluminum alloy according to claim 7, characterized in that: The following steps are involved: S1: Powder preparation: aluminum ingots, magnesium ingots, aluminum-based master alloy ingots or alloy prefabricated ingots are used as alloy raw materials. They are smelted in a vacuum atomization furnace under inert atmosphere protection. The metal liquid is crushed by an inert gas flow with a pressure of 1 to 5 MPa to prepare different types of alloy powders. S2: powder processing, screening, mixing and drying the obtained alloy powder; After sieving, the particle size of the alloy powder is ≤200μm; S3: Additive manufacturing, using laser powder bed fusion technology to perform additive manufacturing on the processed alloy powder; the additive manufacturing process uses argon protection, the oxygen content of the atmosphere is controlled to be less than 150ppm, and the substrate preheating temperature is 150-300℃; S4: High-strength and heat-resistant aluminum alloy is produced after heat treatment.

9. The method for preparing a high-strength heat-resistant aluminum alloy according to claim 7, characterized in that: In step S3, a strip scanning strategy is adopted, the laser power is 265-295 W, the scanning rate is 1600-1800 mm / s, the powder layer thickness is 20-60 μm, and the overlap spacing is 0.13-0.2 mm.

10. The method for preparing the high-strength heat-resistant aluminum alloy according to claim 7, characterized in that: In step S4, the heating temperature of the heat treatment is 310-360° C., and the holding time is 7-12 hours.

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