Low-cost heat-resistant aluminum alloy suitable for selective laser melting as well as preparation method and application of low-cost heat-resistant aluminum alloy

Abstract

The invention relates to a low-cost heat-resistant aluminum alloy suitable for selective laser melting as well as a preparation method and application of the low-cost heat-resistant aluminum alloy, and belongs to the technical field of additive manufacturing aluminum alloys. The heat-resistant aluminum alloy comprises 2.0%-3.4% of Mn; 0.5% to 0.65% of Sc; ni: 1.0% to 2.5%; 1.0% to 1.5% of Fe; 0.61% to 1.0% of La; 1.1% to 1.8% of Ce; zr: 0.25% to 0.45%; and Al: the balance. The content of Mn is controlled to be 3.4% or below, the content of Sc is controlled to be 0.65% or below, meanwhile, the content of Fe is controlled to be 1.0% or above, the production cost can be reduced, the adaptability of the additive manufacturing forming technology can be improved, and it is guaranteed that no cracking problem exists in the printing process.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing of aluminum alloys, and in particular to a low-cost heat-resistant aluminum alloy suitable for laser selective melting, and a preparation method and application thereof. Background Art

[0002] Additive manufacturing offers excellent designability and the ability to rapidly and precisely form complex, thin-walled, and hollow parts, promising broad application prospects in aerospace and other fields. Aluminum alloys, with their excellent specific strength and specific stiffness, are a key lightweight structural material and a preferred choice for additive manufacturing of lightweight structural parts. However, currently, relatively few heat-resistant aluminum alloys are available for additive manufacturing, with relatively low strength at both room and high temperatures. The few high-strength alloys face challenges such as poor adaptability to the forming process.

[0003] With continuous research, the Al-Mn-Sc alloy system has been gradually developed. Its adaptability to additive manufacturing processes is good, and it has become the development direction of additive manufacturing heat-resistant aluminum alloys. However, studies have found that when the Mn content exceeds 6%, the additive manufacturing alloy has a significant tendency to hot cracking and cannot meet the process requirements of additive manufacturing. Reducing the Mn content will lead to a decrease in high-temperature mechanical properties. In addition, the addition of more Mn elements also requires a higher Sc element to enhance the heterogeneous nucleation effect and suppress the tendency to hot cracking. Ultimately, the cost of the Al-Mn-Sc alloy is high, which limits the application of the alloy.

[0004] Therefore, in order to improve the forming process performance, reduce the alloy cost and improve the high-temperature mechanical properties, it is necessary to redesign the alloy composition from other directions. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a low-cost heat-resistant aluminum alloy suitable for laser selective melting and its preparation method and application, thereby reducing the alloy cost while improving the high-temperature mechanical properties and ensuring that the aluminum alloy is free of cracks.

[0006] On the one hand, the present invention provides a low-cost heat-resistant aluminum alloy suitable for laser selective melting, wherein the chemical elements include, by weight percentage, Mn: 2.0% to 3.4%; Sc: 0.5% to 0.65%; Ni: 1.0% to 2.5%; Fe: 1.0% to 1.5%; La: 0.61% to 1.0%; Ce: 1.1% to 1.8%; Zr: 0.25% to 0.45%; and Al: the remainder.

[0007] Furthermore, in terms of weight percentage, the chemical elements include Mn: 2.1% to 3.3%; Sc: 0.5% to 0.65%; Ni: 1.5% to 2.5%; Fe: 1.0% to 1.5%; La: 0.61% to 1.0%; Ce: 1.1% to 1.8%; Zr: 0.28% to 0.33%; and Al: the balance.

[0008] Furthermore, the high-strength and heat-resistant aluminum alloy comprises an aluminum matrix and nano-scale intermetallic compounds dispersed in the aluminum matrix, and the volume fraction of the intermetallic compounds is 8% to 15%.

[0009] Furthermore, at room temperature, the tensile strength is above 600 MPa.

[0010] Furthermore, at 300° C., the tensile strength is above 300 MPa, the yield strength is above 250 MPa, and the elongation exceeds 9%.

[0011] On the other hand, the present invention provides a low-cost method for preparing a heat-resistant aluminum alloy suitable for laser selective melting, wherein the heat-resistant aluminum alloy is obtained by powder preparation, powder processing, additive manufacturing and heat treatment.

[0012] Furthermore, the powder processing includes screening, mixing and drying, and the particle size of the sieved alloy powder is ≤200 μm; the sieved alloy powder is mixed at a rotation speed of 1 r / min to 15 r / min and a duration of 10 min to 60 min.

[0013] Furthermore, in the additive manufacturing process, a strip scanning strategy is adopted, with a laser power of 230 to 265 W, a scanning rate of 1500 to 1700 mm / s, a powder layer thickness of 20 to 60 μm, an overlap spacing of 0.1 to 0.12 mm, and a preheating temperature of 100 to 200 °C.

[0014] Furthermore, the heating temperature of the heat treatment is 300-330° C., and the holding time is 1.5-6 hours.

[0015] Furthermore, the heat-resistant aluminum alloy is used to prepare parts with a service temperature of 250°C to 300°C.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0017] 1. In the present invention, the Mn content is controlled below 3.4%, the Sc content is controlled below 0.65%, and the Fe content is controlled above 1.0%. This not only reduces production costs but also improves the adaptability of the additive manufacturing process and ensures that there is no cracking problem during the printing process.

[0018] 2. In the present invention, Fe element can promote the formation of Al-Mn-Fe quasi-crystal phase in the organization, effectively improving the thermal stability and softening resistance of the organization; at the same time, adding Ni element can form Al3Ni phase, and then combined with Al 11 La3、Al 11 Heat-resistant intermetallic compounds such as Ce3 hinder dislocation migration and exert an Orowan strengthening effect; at the same time, these intermetallic compounds have good thermal stability, which can effectively inhibit the coarsening of the structure during heat treatment and improve the high-temperature strength; at 300°C, the tensile strength is above 300MPa, the yield strength is above 250MPa, and the elongation exceeds 9%.

[0019] 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

[0020] 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.

[0021] Figure 1 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 1;

[0022] Figure 2 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 2;

[0023] Figure 3 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 3;

[0024] Figure 4 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 4;

[0025] Figure 5 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 5;

[0026] Figure 6 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 6;

[0027] Figure 7 This is a metallographic photograph of the heat-resistant aluminum alloy obtained in Example 7.

[0028] Figure 8 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 1;

[0029] Figure 9 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 2;

[0030] Figure 10 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 3;

[0031] Figure 11 This is a physical picture of the aluminum alloy obtained in Comparative Example 4 (with cracks);

[0032] Figure 12 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 5;

[0033] Figure 13 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 6;

[0034] Figure 14 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 7;

[0035] Figure 15 This is a physical picture of the aluminum alloy obtained in Comparative Example 8 (with cracks);

[0036] Figure 16 This is a metallographic photograph of the aluminum alloy obtained in Comparative Example 9. DETAILED DESCRIPTION

[0037] 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.

[0038] 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 heat-resistant aluminum alloys suitable for additive manufacturing is a prerequisite for meeting the lightweight design and integrated manufacturing of lightweight, heat-resistant and complex-shaped parts for additive manufacturing. Although the Al-Mn-Sc alloy system has a certain heat resistance foundation, the tensile strength at 250°C is usually about 250MPa, which still cannot meet the needs of higher temperature or higher load-bearing 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.

[0039] Therefore, the present invention provides a heat-resistant aluminum alloy, which includes, by weight percentage, Mn: 2.0% to 3.4%; Sc: 0.5% to 0.65%; Ni: 1.0% to 2.5%; Fe: 1.0% to 1.5%; La: 0.61% to 1.0%; Ce: 1.1% to 1.8%; Zr: 0.25% to 0.45%; and Al: the balance.

[0040] Compared with the existing technology, the present invention ensures the adaptability of the additive manufacturing forming process by reducing the Mn element content, while reducing the addition of the Sc element, which helps to reduce material costs; in addition, through the mutual cooperation of elements such as Fe and Mn, an Al-Mn-Fe quasi-crystalline phase with better thermal stability is formed in the structure, which can improve the thermal stability of the alloy structure and improve the high-temperature mechanical properties. In addition, by adding elements such as Ni, La, and Ce, intermetallic compounds with good thermal stability are formed, further improving the high-temperature mechanical properties. After performance testing, at 300°C, the tensile strength is above 300MPa, the yield strength is above 250MPa, and the elongation exceeds 9%; at room temperature, the tensile strength can reach 600MPa.

[0041] It should be noted that the elements in the present invention function as follows:

[0042] Mn: Manganese, as the primary alloying element, ensures the forming process adaptability and performance foundation of heat-resistant aluminum alloys. On the one hand, adding 2.0% to 3.4% Mn brings the alloy closer to the Al-Mn eutectic composition, narrowing the solidus-liquidus temperature range and improving its adaptability to additive manufacturing processes. On the other hand, Mn and Al have a large lattice mismatch strain, and adding Mn can achieve significant solid solution strengthening effects.

[0043] Furthermore, Mn has a low thermal diffusion coefficient in the Al matrix, and a shorter heat treatment time reduces Mn precipitation during subsequent heat treatment, maintaining a good solid solution strengthening effect. This also helps control the volume fraction of intermetallic compounds, ensuring an elongation exceeding 9% at 300°C. Even if some Mn atoms precipitate, the presence of an appropriate amount of Fe can form a more stable Al-Mn-Fe quasi-crystalline phase, achieving an Orowan strengthening effect and improving high-temperature strength.

[0044] More importantly, when the adaptability of the alloy forming process is improved, the addition amount of the expensive Sc element can be appropriately reduced, which helps to reduce the cost of the alloy material.

[0045] Sc: Scandium is a precipitation-strengthening element in alloys. However, this element is expensive. Lowering the Sc addition to below 0.65% while reducing the Mn content helps reduce alloy costs. Adjusting the Sc content also helps control grain morphology and size, ensuring improved mechanical properties at both room and high temperatures.

[0046] 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 costs. Therefore, the weight of Zr in the present invention is greater than 46% of the Sc content.

[0047] Fe: The addition of iron helps to promote the formation of Al-Mn-Fe quasi-crystalline phase in the structure, but too much Fe element can easily lead to a decrease in the adaptability of the additive manufacturing forming process and even cracking.

[0048] It should be noted that in the present invention, the elements Ni, La and Ce are added to 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 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 1.0% to 2.5% Ni, 0.61% to 1.0% La, and 1.1% to 1.8% Ce.

[0049] Specifically, in terms of weight percentage, the chemical elements of the heat-resistant aluminum alloy include Mn: 2.1% to 3.3%; Sc: 0.5% to 0.65%; Ni: 1.5% to 2.5%; Fe: 1.0% to 1.5%; La: 0.61% to 1.0%; Ce: 1.1% to 1.8%; Zr: 0.28% to 0.33%; and Al: the balance.

[0050] Specifically, the total amount of alloying elements is 8% to 10%.

[0051] It should be noted that alloying elements include Mn, Sc, Ni, Fe, La, Ce, and Zr, with a total content of 8% to 10%. Below this range, the amount of heat-resistant intermetallic compounds formed in the alloy structure is relatively small, and the room temperature and high temperature strengths are relatively low. Above this range, the number of intermetallic compounds in the alloy structure is greater, which also increases the tendency of the alloy to crack during printing. More Sc elements need to be added to suppress cracking in the formed structure, resulting in higher alloy costs. On the other hand, a higher substrate preheating temperature is required during forming to reduce the temperature gradient and cooling rate, which brings certain difficulties to the forming of large and complex-shaped parts. Therefore, controlling the total amount of alloying elements to 8% to 10% can achieve additive manufacturing of complex-shaped parts while ensuring that the alloy has good room temperature and high temperature mechanical properties and meets the service requirements of 250°C to 300°C.

[0052] 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.

[0053] The present invention provides a low-cost method for preparing a heat-resistant aluminum alloy suitable for laser selective melting. The heat-resistant aluminum alloy is obtained by powder preparation, powder processing, additive manufacturing and heat treatment, and specifically comprises the following steps:

[0054] 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. High-pressure inert gas is used to crush the molten metal into different types of alloy powders.

[0055] S2: powder processing, screening, mixing and drying the obtained alloy powder;

[0056] S3: Additive manufacturing, using laser powder bed fusion technology to perform additive manufacturing on the processed alloy powder;

[0057] S4: Heat-resistant aluminum alloy is obtained after heat treatment.

[0058] 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 300°C, the alloy exhibits a tensile strength exceeding 300 MPa, a yield strength exceeding 250 MPa, and an elongation exceeding 9%. At room temperature, the alloy exhibits a tensile strength of 600 MPa.

[0059] 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.

[0060] Specifically, after screening, the particle size of the alloy powder is ≤200 μm.

[0061] Preferably, after screening, the particle size of the alloy powder is ≤65 μm.

[0062] 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 forming, which is detrimental to ensuring dimensional accuracy and surface quality. To ensure the quality and high-temperature performance of the heat-resistant aluminum alloy, the particle size of the alloy powder should be controlled to no more than 200 μm, preferably below 65 μm.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Specifically, in step S3, a strip scanning strategy is adopted, with a laser power of 230 to 265 W, a scanning rate of 1500 to 1700 mm / s, a powder layer thickness of 20 to 60 μm, and an overlap spacing of 0.1 to 0.12 mm.

[0068] 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 100 to 200°C.

[0069] In the present invention, the laser power may be 230W, 235W, 240W, 245W, 250W, 255W, 260W or 255W.

[0070] In the present invention, the scanning rate may be 1500 mm / s, 1550 mm / s, 1600 mm / s, 1650 mm / s or 1700 mm / s.

[0071] 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.

[0072] In the present invention, the substrate preheating temperature may be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°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 addition, to reduce oxidation and burning during the additive manufacturing process, inert gas (argon) protection is used to ensure that the oxygen content in the forming chamber is less than 150ppm. Excessive oxygen content will lead to severe oxidation and burning, destroying the continuity and integrity of the structure, and ultimately leading to a decrease in mechanical properties.

[0075] Preheating the substrate effectively regulates the cooling rate of the melt during the forming process, suppressing the alloy's cracking tendency. However, excessively high preheat temperatures can reduce the solid solution strengthening effect and decrease the amount of precipitation-strengthening phases after heat treatment, diminishing the precipitation strengthening effect. Because this alloy has good adaptability to forming processes, a preheat temperature of 100-200°C was selected to maintain mechanical properties.

[0076] Specifically, the heating temperature of the heat treatment is 300-330° C., and the holding time is 1.5-6 hours.

[0077] It should be noted that the present invention controls the heating temperature of the heat treatment to be between 300 and 330°C and the holding time to be between 1.5 and 6 hours. Since the total amount of alloying elements is 8% to 10%, the heat treatment of 300 to 330°C / 1.5 to 6 hours can ensure that the content of intermetallic compounds precipitated in the alloy is within a controllable range, thereby ensuring higher strength while obtaining better plasticity. If the temperature is too low or the holding time is too short, the volume fraction of the precipitation strengthening phase cannot be guaranteed; if the temperature is too high or the holding time is too long, it will cause excessive precipitation of the precipitated phase or unnecessary coarsening and growth, weakening the plasticity of the material and resulting in a waste of preparation costs. The high-strength and heat-resistant aluminum alloy is an aluminum matrix and nano-scale intermetallic compounds are dispersed in the aluminum matrix, and the volume fraction of the intermetallic compounds is 8% to 15%.

[0078] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.

[0079] Example 1

[0080] The preparation process of heat-resistant aluminum alloy is as follows:

[0081] 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;

[0082] S2: Powder processing: the alloy powder is sieved to obtain alloy powder of ≤53μm, 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;

[0083] 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 0.12mm; argon gas protection is used during the forming process, and the oxygen content of the atmosphere is controlled at 140ppm; the substrate is preheated to 150℃ during the forming process and removed after cooling;

[0084] S4: The sample is heat treated in a heating furnace at a holding temperature of 325°C for 3 hours, and then cooled in the furnace to obtain a heat-resistant aluminum alloy.

[0085] Examples 2-4, Comparative Examples 1-3

[0086] 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.

[0087] Table 1 Different parameters of Examples 1-4 and Comparative Examples 1-3 (unit: wt%)

[0088]

[0089] *“-” in Table 1 means no addition.

[0090] Comparative Examples 4-5

[0091] The difference between Comparative Examples 4-5 and Example 1 lies in the different alloy compositions, as shown in Table 2.

[0092] Table 2 Different parameters of comparative examples 4-5 (unit: wt%)

[0093]

[0094] *“-” in Table 2 means no addition.

[0095] Examples 5-7, Comparative Examples 6-9

[0096] The difference between Examples 5-7 and Comparative Examples 6-9 and Example 1 lies in the different preparation methods, as shown in Table 3.

[0097] Table 3 Different parameters of Examples 5-7, Comparative Examples 6-9 and Example 1

[0098]

[0099]

[0100] Performance testing

[0101] The above examples and comparative examples were subjected to performance tests. The microstructure of the materials was observed and the tensile properties at high temperature (300°C) and room temperature were tested according to GB / T 3246.1-2012, HB5195-1996, and HB 5143-1996. The test results are shown in Tables 4 and 5, respectively.

[0102] Table 4 Performance test results (300℃)

[0103] Group Tensile strength / MPa Yield strength / MPa Elongation / % Remark Example 1 338 301 14.5 Example 2 334 293 12.2 Example 3 308 252 9.2 Example 4 329 287 10.5 Example 5 311 257 10.8 Example 6 318 262 11.4 Example 7 304 251 9.5 Comparative Example 1 - - - Cracking Comparative Example 2 208 193 14.8 Comparative Example 3 232 210 13.4 Comparative Example 4 - - - Cracking Comparative Example 5 205 180 7.7 Comparative Example 6 235 203 9.2 Comparative Example 7 216 164 9.6 Comparative Example 8 - - - Cracking Comparative Example 9 194 256 10.8

[0104] Table 5 Performance test results (room temperature)

[0105] Group Tensile strength / MPa Yield strength / MPa Remark Example 1 650 563 Example 2 621 526 Example 3 602 491 Example 4 634 547 Example 5 628 540 Example 6 624 537 Example 7 611 509 Comparative Example 1 - - Cracking Comparative Example 2 611 555 Comparative Example 3 528 473 Comparative Example 4 - - Cracking Comparative Example 5 598 533 Comparative Example 6 586 477 Comparative Example 7 577 486 Comparative Example 8 - - Cracking Comparative Example 9 573 482

[0106] Combined with Examples 1-7 and Comparative Examples 1-9 and Tables 4, 5 and Figure 1-16 It can be seen that when using the compositions and proportions provided in Examples 1-7, the coordination of Mn, Sc, Fe, and Ni, La, Ce, and other elements results in high room temperature and high temperature strength. However, the low Mn and Sc content effectively controls production costs.

[0107] After additive manufacturing, the resulting aluminum alloy was tested at room temperature and at 300°C. At room temperature, the resulting alloy exhibited a tensile strength of 602-650 MPa and a yield strength of 491-563 MPa. At 300°C, the alloy exhibited a tensile strength of 304-338 MPa, a yield strength of 251-301 MPa, and an elongation of 9.5-14.5%, with no internal cracks. The high-strength, heat-resistant aluminum alloy consists of an aluminum matrix with nanoscale intermetallic compounds dispersed within it, with the volume fraction of the intermetallic compounds ranging from 8-14%.

[0108] 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 low-cost heat-resistant aluminum alloy suitable for laser selective melting, characterized in that: In terms of weight percentage, the chemical elements include Mn: 2.0% to 3.4%; Sc: 0.5% ~ 0.65%; Ni: 1.0% ~ 2.5%; Fe: 1.0%~1.5%; La: 0.61%~1.0%; Ce: 1.1%~1.8%; Zr: 0.25%~0.45%; Al: balance.

2. The low-cost heat-resistant aluminum alloy suitable for laser selective melting according to claim 1, characterized in that: In terms of weight percentage, the chemical elements include Mn: 2.1% to 3.3%; Sc: 0.5% to 0.65%; Ni: 1.5% to 2.5%; Fe: 1.0%~1.5%; La: 0.61% to 1.0%; Ce: 1.1% to 1.8%; Zr: 0.28% to 0.33%; Al: balance.

3. The low-cost heat-resistant aluminum alloy suitable for laser selective melting according to claim 1 or 2, characterized in that: The heat-resistant aluminum alloy comprises an aluminum matrix and nano-scale intermetallic compounds dispersed in the aluminum matrix, and the volume fraction of the intermetallic compounds is 8% to 15%.

4. The low-cost heat-resistant aluminum alloy suitable for laser selective melting according to claim 1 or 2, characterized in that: At room temperature, the tensile strength is above 600 MPa.

5. The low-cost heat-resistant aluminum alloy suitable for selective laser melting according to claim 1 or 2, characterized in that: At 300°C, the tensile strength is above 300 MPa, the yield strength is above 250 MPa, and the elongation exceeds 9%.

6. A method for preparing a heat-resistant aluminum alloy suitable for selective laser melting at low cost according to any one of claims 1 to 5, characterized in that: Heat-resistant aluminum alloys are obtained through powder preparation, powder processing, additive manufacturing and heat treatment.

7. The low-cost heat-resistant aluminum alloy suitable for selective laser melting according to claim 6, characterized in that: The powder processing includes screening, mixing and drying. The particle size of the sieved alloy powder is ≤200 μm. The sieved alloy powder is mixed at a rotation speed of 1 r / min to 15 r / min and a duration of 10 min to 60 min.

8. The low-cost heat-resistant aluminum alloy suitable for selective laser melting according to claim 6, characterized in that: During the additive manufacturing process, a strip scanning strategy is adopted, with a laser power of 230 to 265 W, a scanning rate of 1500 to 1700 mm / s, a powder layer thickness of 20 to 60 μm, an overlap spacing of 0.1 to 0.12 mm, and a preheating temperature of 100 to 200 °C.

9. The low-cost heat-resistant aluminum alloy suitable for selective laser melting according to claim 6, characterized in that: The heating temperature of the heat treatment is 300-330°C, and the holding time is 1.5-6h.

10. Application of the low-cost heat-resistant aluminum alloy suitable for selective laser melting according to any one of claims 1 to 5, characterized in that: The heat-resistant aluminum alloy is used to prepare parts with a service temperature of 250°C to 300°C.

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