High-temperature-resistant aluminum alloy powder for additive manufacturing and preparation method

Abstract

The invention belongs to the field of aluminum alloy smelting, and particularly relates to high-temperature-resistant aluminum alloy powder for additive manufacturing and a preparation method of the high-temperature-resistant aluminum alloy powder. The alloy comprises: 5.0 to 15.0 wt% of lanthanum (La), not more than 1.0 wt% of scandium (Sc), and not more than 1.0 wt% of zirconium (Zr); optionally, the aluminum alloy further comprises less than or equal to 5 wt% of magnesium (Mg), less than or equal to 1 wt% of manganese (Mn) and the balance of aluminum (Al). Bulk materials formed through selective laser melting additive manufacturing of the high-temperature-resistant aluminum alloy powder are free of cracks, the eutectic phase structure is of a submicron-scale cellular network structure, the room-temperature tensile strength obtained after simple heat treatment is larger than 450 MPa, and the ductility is larger than 7%. And under 300 DEG C heat-resistant tensile loading, the tensile strength is 250 MPa. The preparation method of the high-temperature-resistant aluminum alloy powder is simple in step and mature in technology, and has wide application prospects in the fields of aerospace, rail transit, automobiles, electronics and the like.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum alloy smelting, and relates to the composition design and preparation of aluminum alloy powder, and specifically to a high-temperature resistant aluminum alloy powder for additive manufacturing and a preparation method thereof. Background Art

[0002] Traditional manufacturing technology has certain limitations in the manufacture of complex-shaped parts, which limits the design freedom and forming speed. However, additive manufacturing technology, also known as 3D printing technology, breaks through these limitations, can achieve rapid forming of complex-shaped parts, and further improve the lightweight level of the structure through topology optimization technology.

[0003] Aluminum alloys are known for their low density and high specific strength and are the representative of lightweight structural materials. The use of additive manufacturing technology to form aluminum alloy parts can not only achieve lightweight materials, but also achieve further lightweight effects through structural design, thereby exerting the greatest potential in energy saving and efficiency improvement. In view of its lightweight advantages, additively manufactured aluminum alloy parts have shown great application potential in high-end fields such as national defense, military industry, aerospace, etc. Key components in the aerospace field (such as aircraft engines) are usually in high-temperature service, which puts higher requirements on the high-temperature mechanical properties of materials. However, the use temperature of most aluminum alloys, including traditional heat-resistant aluminum alloys (such as 2618, ZL205, etc.) and typical additively manufactured aluminum alloys (AlSi0Mg, etc.) is usually not higher than 200°C. At high temperatures above 300°C, the strength of the material is very limited, which seriously limits the wide application of aluminum alloys in key components of aerospace high-temperature service. This is mainly because under high-temperature loading, dislocation slip and climb in the aluminum matrix are greatly stimulated, resulting in matrix softening. At the same time, common alloying elements (such as Cu, Mg, and Si) in aluminum alloys are prone to diffusion under high temperature environments, causing Ostward ripening and growth of component phases, thereby reducing the strengthening effect. Summary of the invention

[0004] In order to solve the above problems, an object of the present invention is to provide a high temperature resistant aluminum alloy powder for additive manufacturing and a preparation method thereof.

[0005] In order to improve the high temperature strength of aluminum alloys, on the one hand, alloying elements with low diffusion coefficients and low solubility in the aluminum matrix can be selected to prevent the coarsening of component phases at high temperatures. On the other hand, alloying elements that can form component phases with a connected network structure in aluminum alloys can be selected to inhibit the slip and climb of dislocations in the aluminum matrix under high temperature environments. The diffusion coefficients and solubilities of elements such as La, Sc, and Zr in the aluminum matrix are extremely low (2 to 5 orders of magnitude lower than elements such as Si, Cu, and Mg at 400°C), which can form high temperature stable coarsening-resistant Al-La eutectic phases and Al3 (Sc, Zr) nanoparticle precipitation phases. In addition, due to the rapid solidification characteristics of additive manufacturing, the microstructure of the eutectic aluminum alloy formed by additive manufacturing presents a three-dimensional connected submicron cellular network structure. At the same time, the content of the alloying element La can be adjusted to make it close to the Al-La eutectic point to reduce the solidification temperature range of the alloy, and a small amount of Sc and Zr elements can be added to promote heterogeneous nucleation during the solidification process, reduce the hot cracking sensitivity of the alloy, and improve the printing formability of the aluminum alloy. Based on the above analysis, low diffusion coefficient and low solubility elements La, Sc, and Zr are introduced into aluminum alloys. The introduction of La element can form a thermally stable and coarsening-resistant Al-La eutectic phase with Al, and form a thermally stable three-dimensional interconnected cellular network microstructure through additive manufacturing; and the introduction of trace amounts of Sc and Zr can form Al3 (Sc, Zr) coarsening-resistant nanoprecipitation phase in the aluminum matrix. In theory, the high-temperature mechanical properties of aluminum alloys can be improved through the dual effects of load-bearing strengthening of the Al-La eutectic phase and strengthening of Al3 (Sc, Zr) nanoparticles, thereby developing a high-temperature resistant aluminum alloy for additive manufacturing.

[0006] In one aspect, the present invention provides a high temperature resistant aluminum alloy, characterized in that the aluminum alloy comprises:

[0007] 5.0-15.0 wt% of lanthanum (La), not more than 1.0 wt% of scandium (Sc), and not more than 1.0 wt% of zirconium (Zr);

[0008] Optionally, less than or equal to 5 wt % of magnesium (Mg), and less than or equal to 1 wt % of manganese (Mn).

[0009] In some embodiments, the aluminum alloy contains 5.0-15.0 wt% lanthanum, for example, 5.0-12.0 wt%, 5.0-10.5 wt%, 7.0-12.0 wt%, 7.0-10.5 wt%, 9.0-10.5 wt%, 9.0-12.0 wt%, or 9.0-15.0 wt%, and further can be 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0-12.0 wt%, 7.0-10.5 wt%, 9.0-10.5 wt%, 9.0-12.0 wt%, or 9.0-15.0 wt%. .0wt%, 7.5wt%, 8.0wt%, 8.5wt%, 9.0wt%, 9.1wt%, 9.5wt%, 9.8wt%, 10.0wt%, 10.5wt%, 11.0wt%, 11.5wt%, 12.0wt%, 12.5wt%, 13.0wt%, 13.5wt%, 14.0wt%, 14.5wt%, 15.0wt% or a range between any two of the foregoing.

[0010] In some embodiments, the aluminum alloy contains no more than 1.0 wt% scandium, for example, no more than 0.9 wt%, no more than 0.8 wt%, no more than 0.7 wt%, no more than 0.6 wt%, no more than 0.5 wt%, no more than 0.4 wt%, no more than 0.3 wt%, no more than 0.2 wt%, no more than 0.1 wt%, and further 0.1-1.0 wt%, 0.1-0.3 wt%, 0.2-0.5 wt%, 0.2-0.6 wt%, 0.6-1.0 wt%, 0.1-0.7 wt%, 0.2-0.7 wt%, or 0. 7-1.0wt% and can further be 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.29wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.46wt%, 0.5wt%, 0.51wt%, 0.55wt%, 0.6wt%, 0.61wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt%, 1.0wt% or a range between any two of the foregoing.

[0011] In some embodiments, the aluminum alloy includes no more than 1.0 wt% zirconium, for example, no more than 0.9 wt%, no more than 0.8 wt%, no more than 0.7 wt%, no more than 0.6 wt%, no more than 0.5 wt%, no more than 0.4 wt%, no more than 0.3 wt%, no more than 0.2 wt%, no more than 0.1 wt%, and further may be 0.1-1.0 wt%, 0.1-0.2 wt%, 0.1-0.3 wt%, 0.1-0.4 wt%, 0.1-0.8 wt%, 0.2-1.0 wt%, 0.3-1.0 wt%, 0.2-0.8wt% or 0.7-1.0wt%, and can further be 0.05wt%, 0.1wt%, 0.12wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.26wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt%, 1.0wt% or any range between two of the foregoing.

[0012] In some embodiments, the aluminum alloy contains less than or equal to 5wt% magnesium, for example, less than or equal to 4.5wt%, less than or equal to 4.0wt%, less than or equal to 3.5wt%, less than or equal to 3.0wt%, less than or equal to 2.5wt%, less than or equal to 2.0wt%, less than or equal to 1.5wt%, less than or equal to 1.0wt%; in some preferred embodiments, the aluminum alloy contains 0-5wt% magnesium, for example, 0-4.5wt%, 0-4.0wt%, 0-3.5wt%, 0-3.0wt%, 0-2.5wt%, 0-2.0wt%, 0-1.5wt% or 0-1.0wt%, and can further be 5.0wt%, 4.5wt%, 4.0wt%, 3.5wt%, 3.0wt%, 2.5wt%, 2.0wt%, 1.5wt%, 1.0wt% or a range between any two of the foregoing.

[0013] In some embodiments, the aluminum alloy contains less than or equal to 1wt% manganese, for example, less than or equal to 0.9wt%, less than or equal to 0.8wt%, less than or equal to 0.7wt%, less than or equal to 0.6wt%, less than or equal to 0.5wt%, less than or equal to 0.4wt%, less than or equal to 0.3wt%, less than or equal to 0.2wt%, less than or equal to 0.1wt%; in some preferred embodiments, the aluminum alloy contains 0-1wt% manganese, for example, 0-0.9wt%, 0-0.8wt%, 0-0.7wt%, 0-0.6wt%, 0-0.5wt%, 0-0.4wt%, 0-0.3wt%, 0-0.2wt% or 0-0.1wt%, and can further be 0.9wt%, 0.8wt%, 0.7wt%, 0.6wt%, 0.5wt%, 0.4wt%, 0.3wt%, 0.2wt%, 0.1wt% or a range between any two of the foregoing.

[0014] In some embodiments, the aluminum alloy comprises: 7.0-12.0 wt % lanthanum (La), preferably 7.0-9.5 wt %, or 9.5-11.0 wt %, or 11.0-12.0 wt %.

[0015] In some embodiments, the aluminum alloy includes 0.1-1.0 wt % of scandium (Sc), preferably 0.1-0.3 wt %, or 0.3-0.5 wt %, or 0.5-0.7 wt %.

[0016] In some embodiments, the aluminum alloy includes 0.1-1.0 wt % zirconium (Zr), preferably 0.1-0.2 wt %, or 0.2-0.4 wt %, or 0.6-0.8 wt %.

[0017] In some optional embodiments, the aluminum alloy contains less than or equal to 2 wt % magnesium (Mg), preferably 1-2 wt %.

[0018] In some optional embodiments, the aluminum alloy contains less than or equal to 0.6 wt % manganese (Mn), preferably 0.5-0.6 wt %.

[0019] In some embodiments, the aluminum alloy comprises 9.80 wt % lanthanum, 0.46 wt % scandium, and 0.26 wt % zirconium; optionally, the aluminum alloy comprises less than or equal to 5 wt % magnesium and less than or equal to 1 wt % manganese.

[0020] In some embodiments, the aluminum alloy comprises 11.5 wt % lanthanum, 0.29 wt % scandium, and 0.12 wt % zirconium; optionally, the aluminum alloy comprises less than or equal to 5 wt % magnesium and less than or equal to 1 wt % manganese.

[0021] In some embodiments, the aluminum alloy comprises 9.10 wt % lanthanum, 0.61 wt % scandium, and 0.75 wt % zirconium; optionally, the aluminum alloy comprises less than or equal to 5 wt % magnesium and less than or equal to 1 wt % manganese.

[0022] In some embodiments, the aluminum alloy includes: 10.5 wt % lanthanum, 0.51 wt % scandium, 0.35 wt % zirconium, 1.5 wt % magnesium, 0.6 wt % manganese.

[0023] In some embodiments, the aluminum alloy further includes aluminum (Al) and inevitable impurities as the balance.

[0024] In some embodiments, the impurity includes at least one of boron, titanium, silicon, chromium, vanadium, manganese, zinc, phosphorus, calcium, nickel, copper, cerium, or lithium.

[0025] In some embodiments, the aluminum alloy is manufactured in powder form.

[0026] In some embodiments, the aluminum alloy in powder form is used in an additive manufacturing process.

[0027] In some embodiments, the aluminum alloy in powder form for additive manufacturing has a particle size of 10-60 μm, such as 10-15 μm, 15-60 μm, 15-53 μm or 10-53 μm, preferably 15-53 μm.

[0028] In another aspect, the present invention provides a method for producing the aluminum alloy in powder form, the method comprising the following steps: melting an alloy preform ingot and forming the alloy powder by gas atomization.

[0029] In some embodiments, the smelting of the alloy preform ingot comprises steps S1-S5, and the gas atomization forming of the alloy powder comprises steps S6-S8:

[0030] S1. According to the weight ratio of the chemical components of the alloy, high-purity Al, Al-La master alloy block, Al-Sc master alloy block, and Al-Zr master alloy block are weighed as raw materials, and optionally, the raw materials also include high-purity Mg;

[0031] S2, mixing Al and Al-La master alloy blocks, adding them into a crucible, placing them in a resistance furnace, heating and stirring until melt A is completely melted, and then keeping the temperature;

[0032] S3, adding the Al-Sc master alloy block to the melt A, stirring slightly after it is completely melted to obtain melt B, and then keeping the temperature;

[0033] S4, adding a refining agent to melt B for refining, and removing the surface scum;

[0034] S5. After refining, a covering agent is sprinkled on the melt B for vacuum degassing, and the surface scum is removed again, and then casting and air cooling are performed to obtain a prefabricated ingot C;

[0035] S6, after placing the prefabricated ingot C into the crucible in the melting chamber of the gas atomization equipment, the air in the melting chamber is replaced by nitrogen;

[0036] S7, maintaining the prefabricated ingot C at the melting temperature by electromagnetic induction heating to completely melt the ingot;

[0037] S8. Use high-speed compressed argon gas to impact the aluminum alloy prefabricated ingot C melt. The high-speed gas breaks the melt into tiny droplets, which solidify into tiny powders during the descent process. After collection and vacuum packaging, the finished alloy powder is obtained.

[0038] In some preferred embodiments, the melting temperature in step S2 is 700-1000°C, for example, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, preferably 700-900°C, more preferably 800°C.

[0039] In some preferred embodiments, the insulation temperature of step S2 is 840-860°C, for example, 840°C, 845°C, 850°C, 855°C or 860°C, preferably 845-855°C, more preferably 850°C.

[0040] In some preferred embodiments, the insulation time of step S2 is 5-15 min, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 min, preferably 10-15 min, and more preferably 15 min.

[0041] In some preferred embodiments, the insulation temperature of step S3 is 750-770°C, for example, 750°C, 755°C, 760°C, 765°C or 770°C, preferably 755-765°C, more preferably 760°C.

[0042] In some preferred embodiments, the insulation time of step S3 is 5-15 min, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 min, preferably 5-10 min, and more preferably 5 min.

[0043] In some preferred embodiments, the refining time in step S4 is 5-10 min, for example, 5, 6, 7, 8, 9 or 10 min, preferably 5 min.

[0044] In some preferred embodiments, the degassing time in step S5 is actually 10-20 min, for example, it can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 min, preferably 10-15 min, more preferably 10 min.

[0045] In some preferred embodiments, the melt temperature during casting in step S5 is 740±5°C, for example, it can be 735°C, 736°C, 737°C, 738°C, 739°C, 740°C, 741°C, 742°C, 743°C, 744°C or 745°C, preferably 740°C.

[0046] In some preferred embodiments, the holding time of step S7 is 5-120 min, for example, it can be 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120 min, preferably 20-40 min, and more preferably 30 min.

[0047] In some preferred embodiments, the smelting temperature in step S7 is not less than 800°C, for example, it can be 800-1000°C, 800-900°C, 800-850°C, and can further be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 900°C, 950°C or 1000°C, preferably 800°C.

[0048] In some preferred embodiments, the purity of the argon gas in step S8 is ≥ 99.999%, for example, the purity of the argon gas may be 99.999%-100%.

[0049] In some embodiments, the method comprises the steps of:

[0050] S1, adding high-purity Al, Al-La master alloy block, and Al-Zr master alloy block into a crucible and heating them in a resistance furnace, and optionally, the raw materials further include high-purity Mg;

[0051] S2. Melt it completely at a melting temperature of 700℃-1000℃, then keep it at 850±5℃ for 10 minutes. After keeping it warm, remove the scum on the surface.

[0052] S3. Add Al-Sc master alloy block, stir the melt slightly, cool the melt to 760±5℃, and keep it warm for 5 minutes.

[0053] S4, maintaining the melt temperature at 760±5℃, adding refining agent and refining for 5min, then removing the surface scum;

[0054] S5. After refining, the coating agent is sprinkled on the surface for vacuum degassing for 10 minutes, and the surface scum is removed again. When the melt temperature is measured at 740±5°C, a prefabricated ingot is cast and air-cooled to obtain a prefabricated ingot;

[0055] S6, placing the prefabricated ingot obtained in step S5 into a crucible in a smelting chamber of a gas atomization device, and replacing the air in the smelting chamber with nitrogen;

[0056] S7, by electromagnetic induction heating, the prefabricated ingot is completely melted and maintained at the melting temperature for 5min-120min, so that the ingot is completely melted, and the melting temperature is not less than 800°C;

[0057] S8. The molten prefabricated ingot melt flows out from the nozzle, is broken into tiny droplets under the impact of high-speed argon gas, and solidifies into powder. The Al-La-Sc-Zr alloy powder product is obtained after being collected and vacuum-packaged.

[0058] On the other hand, the present invention provides an aluminum alloy block, which is prepared from the above-mentioned aluminum alloy in powder form.

[0059] In some embodiments, the aluminum alloy block is prepared by additive manufacturing.

[0060] In some embodiments, the preparation further comprises aging heat treatment.

[0061] In some embodiments, the additive manufacturing includes one or more selected from the group consisting of selective laser melting additive manufacturing, laser directed energy deposition additive manufacturing, electron beam selective melting additive manufacturing, and electron beam directed energy deposition additive manufacturing.

[0062] In some embodiments, the additive manufacturing is a selective laser melting process.

[0063] In some embodiments, the scanning strategy of the selective laser melting additive manufacturing is strip scanning.

[0064] In some embodiments, the scanning speed of the selective laser melting additive manufacturing is 1000-2000 mm / s, for example, it can be 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900 or 2000 mm / s, preferably 1300-1800 mm / s.

[0065] In some embodiments, the laser power of the selective laser melting additive manufacturing is not higher than 220 W, for example, not higher than 210 W or not higher than 200 W. In some embodiments, the laser power of the selective laser melting additive manufacturing is 150-220 W, for example, 150, 160, 170, 180, 190, 200, 210 or 200 W, preferably 150-200 W, more preferably 160-200 W.

[0066] In some embodiments, the scanning pitch of the selective laser melting additive manufacturing is 80-120 μm, for example, 80, 90, 100, 110 or 120 μm, preferably 100 μm.

[0067] In some embodiments, the scanning layer thickness of the selective laser melting additive manufacturing is 20-40 μm, for example, it can be 20, 25, 30, 35 or 40 μm, preferably 30 μm.

[0068] In some embodiments, the scanning method of the selective laser melting additive manufacturing is layer-by-layer scanning with a rotation of 67 degrees.

[0069] In some embodiments, the aging heat treatment comprises the following steps: performing aging heat treatment at 300-350° C. for 30 min-1 h, followed by cooling in air.

[0070] In some preferred embodiments, the aging heat treatment temperature is 325°C.

[0071] In some preferred embodiments, the aging heat treatment time is 1 hour.

[0072] In some preferred embodiments, the laser power of the selective laser melting additive manufacturing is 200 W, the scanning speed is 1500 mm / s, the scanning layer thickness is 30 μm, the scanning interval is 100 μm, and the scanning mode is layer-by-layer scanning with a rotation of 67 degrees.

[0073] In some preferred embodiments, the laser power of the selective laser melting additive manufacturing is 200 W, the scanning speed is 1800 mm / s, the scanning layer thickness is 30 μm, the scanning interval is 100 μm, and the scanning method is layer-by-layer scanning with a rotation of 67 degrees.

[0074] In some preferred embodiments, the laser power of the selective laser melting additive manufacturing is 160 W, the scanning speed is 1300 mm / s, the scanning layer thickness is 30 μm, the scanning interval is 100 μm, and the scanning method is layer-by-layer scanning with a rotation of 67 degrees.

[0075] In some embodiments, the aluminum alloy block withstands a temperature of not less than 300°C, such as 300-400°C, 300-350°C, or 300-330°C.

[0076] In some embodiments, the aluminum alloy block is crack-free, and no substantial number of pores are observed.

[0077] In some embodiments, the room temperature tensile strength of the aluminum alloy block is not less than 350 MPa, for example, not less than 380 MPa, not less than 400 MPa, not less than 450 MPa. In some preferred embodiments, the room temperature tensile strength of the aluminum alloy block is not less than 380 MPa. In some preferred embodiments, the room temperature tensile strength of the aluminum alloy block is not less than 450 MPa.

[0078] In some embodiments, the room temperature tensile strength of the aluminum alloy block is 350 MPa-500 MPa, for example, 380-500 MPa, 400-500 MPa, 410-500 MPa, 450-500 MPa, 380-480 MPa or 380-460 MPa, and further can be 350 MPa, 360 MPa, 370 MPa, 380 MPa, 385 MPa, 390 MPa, 395 MPa, 400 MPa, 405 MPa, 410 MPa, a. 415MPa, 415MPa, 420MPa, 425MPa, 430MPa, 435MPa, 440MPa, 444MPa, 445MPa, 450MPa, 45 1MPa, 453MPa, 455MPa, 457MPa, 460MPa, 461MPa, 470MPa, 480MPa, 481MPa, 490MPa or 500MPa.

[0079] In some embodiments, the room temperature elongation of the aluminum alloy block is not less than 4%, for example, it can be not less than 5%, not less than 6%, not less than 7%, not less than 8%, not less than 9%, not less than 10%. In some preferred embodiments, the room temperature elongation of the aluminum alloy block is not less than 7%.

[0080] In some embodiments, the room temperature elongation of the aluminum alloy block is 4%-10%, for example, it can be 4%-9%, 4%-8%, 4%-7%, 4%-6%, 4%-5%, 5%-10%, 6%-10%, 7%-10%, 8%-10% or 5-9%, and can further be 4%, 4.4%, 4.5%, 4.7%, 5%, 5.5%, 6%, 6.1%, 6.5%, 7%, 7.1%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

[0081] In some embodiments, the room temperature yield strength of the aluminum alloy block is not less than 300 MPa, for example, it may be not less than 350 MPa, not less than 400 MPa, not less than 410 MPa, not less than 420 MPa, not less than 430 MPa, not less than 440 MPa. In some preferred embodiments, the room temperature yield strength of the aluminum alloy block is not less than 400 MPa.

[0082] In some embodiments, the room temperature yield strength of the aluminum alloy block is 300 MPa-450 MPa, for example, it can be 350-450MPa, 400-450MPa, 410-450MPa, 420-450MPa, 430-450MPa, 440-450MPa, and further can be 300MPa, 303MPa, 310MPa, 320MPa, 330MPa, 340MPa, 350MPa, 360MPa, 370MPa, 380MPa, 390MPa, 400MPa, 410MPa, 411MPa, 412MPa, 413MPa, 414MPa, 415MPa, 416MPa, 417MPa, 418MPa, 419MPa, 420MPa, 423MPa, 425MPa, 430MPa, 440MPa or 450MPa.

[0083] The room temperature is 15-25°C, preferably 20-25°C.

[0084] In some embodiments, the tensile strength of the aluminum alloy block at 300°C is not less than 200 MPa, for example, it may be not less than 210 MPa, not less than 220 MPa, not less than 230 MPa, not less than 240 MPa, not less than 250 MPa or not less than 260 MPa. In some preferred embodiments, the tensile strength of the aluminum alloy block at 300°C is not less than 250 MPa.

[0085] In some embodiments, the tensile strength of the aluminum alloy block at 300°C is 200 MPa-300 MPa, for example, it can be 230-300 MPa, 240-300 MPa, 250-300 MPa, 260-300 MPa, 270-300 MPa, 230-280 MPa or 230-270 MPa, and can further be 200 MPa, 210 MPa, 220 MPa, 228 MPa, 230 MPa, 231 MPa, 240 MPa, 248 MPa, 250 MPa, 251 MPa, 255 MPa, 260 MPa, 266 MPa, 270 MPa, 280 MPa, 290 MPa or 300 MPa.

[0086] In some embodiments, the aluminum alloy block has an elongation of not less than 5% at 300°C, for example, not less than 6%, not less than 7%, not less than 8%, not less than 9%, not less than 10%. In some preferred embodiments, the aluminum alloy block has an elongation of not less than 7% at room temperature.

[0087] In some embodiments, the elongation of the aluminum alloy block at 300°C is 5%-10%, for example, it can be 5%-9%, 5%-8%, 5%-7%, 5%-6%, 6%-10%, 7%-10%, 8%-10% or 5-9%, and can further be 4%, 4.5%, 5%, 5.5%, 6%, 6.2%, 6.5%, 6.6%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

[0088] In some embodiments, the yield strength of the aluminum alloy block at 300° C. is not less than 200 MPa, for example, may be not less than 210 MPa, not less than 220 MPa, not less than 230 MPa, or not less than 240 MPa.

[0089] In some embodiments, the yield strength of the aluminum alloy block at 300°C is 200 MPa-250 MPa, for example, it can be 210-250 MPa, 220-250 MPa, 230-250 MPa, 240-250 MPa, 200-220 MPa, 210-240 MPa, 210-230 MPa or 210-220 MPa, and can further be 200 MPa, 205 MPa, 210 MPa, 215 MPa, 217 MPa, 220 MPa, 225 MPa, 229 MPa, 230 MPa, 235 MPa, 240 MPa, 243 MPa, 245 MPa or 250 MPa.

[0090] In some embodiments, the aluminum alloy bulk material has grains that form a mixed structure of equiaxed crystals and columnar crystals.

[0091] In some embodiments, the equiaxed crystal size is 1-5 μm, for example, 1, 2, 3, 4 or 5 μm.

[0092] In some embodiments, the columnar crystal size is no greater than 50 μm, for example no greater than 40 μm, no greater than 30 μm, no greater than 20 μm, no greater than 10 μm. Preferably, the columnar crystal size is 0-50 μm.

[0093] In some embodiments, the eutectic phase organization is a sub-micrometer scale cellular network structure.

[0094] In yet another aspect, the present invention provides use of the aluminum alloy or the aluminum alloy prepared by the method in additive manufacturing.

[0095] In yet another aspect, the present invention provides use of the above aluminum alloy, the aluminum alloy prepared by the above method, or the above aluminum alloy block in preparing aluminum alloy parts.

[0096] In some embodiments, the aluminum alloy component is used in aerospace equipment, rail transportation equipment, automobiles, or electronic products.

[0097] Advantages of the invention

[0098] (1) By introducing La, Sc and Zr, which have low diffusion coefficients and low solubility elements in aluminum alloys, a three-dimensional interconnected, thermally stable and coarsening-resistant Al-La eutectic phase cellular network structure is obtained by additive manufacturing, and Al3(Sc,Zr) nanoprecipitates are formed in the aluminum matrix by heat treatment. The high-temperature mechanical properties of aluminum alloys are improved by the coupling effect of the load-bearing strengthening of the Al-La cellular network structure and the strengthening of Al3(Sc,Zr) nanoparticles.

[0099] (2) By designing a near-Al-La eutectic composition, the solidification temperature range of the alloy is reduced, and by microalloying Sc and Zr elements to promote heterogeneous nucleation of grains during the solidification process, the thermal cracking sensitivity of the alloy is greatly reduced, the printing formability is improved, and the additive manufacturing processing parameter window is effectively broadened.

[0100] (3) The Al-La-Sc-Zr alloy powder preparation method of the present invention is simple, the process is mature, the cost is controllable, and large-scale industrial production can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 The typical particle morphology of the Al-La-Sc-Zr alloy powder in Example 1 and its additively manufactured block sample are shown.

[0102] Figure 2 The typical grain structure and eutectic phase cellular network microstructure of the printed Al-La-Sc-Zr alloy in Example 1 are shown.

[0103] Figure 3 The room temperature tensile curve of the printed Al-La-Sc-Zr alloy in Example 1 and the room temperature tensile curve and 300°C high temperature tensile curve of the heat-treated Al-La-Sc-Zr alloy in Example 2 are shown.

[0104] Figure 4 The room temperature tensile curve and 300°C high temperature tensile curve of the Al-La-Sc-Zr alloy heat-treated in Example 3 are shown.

[0105] Figure 5 The room temperature tensile curve and 300°C high temperature tensile curve of the Al-La-Sc-Zr alloy heat-treated in Example 4 are shown.

[0106] Figure 6 The room temperature tensile curve and 300°C high temperature tensile curve of the Al-La-Sc-Zr alloy heat-treated in Example 5 are shown.

[0107] Figure 7 The room temperature tensile curve and 300°C high temperature tensile curve of the Al-La-Sc-Zr alloy heat-treated in Example 6 are shown. DETAILED DESCRIPTION

[0108] For the purpose of clear and concise description, features are described herein as part of some identical or separate embodiments, however, it will be understood that the scope of the present disclosure may include some embodiments having a combination of all or some of the described features. The technical solution of the present invention will be clearly and completely described below. Obviously, based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0109] I. Definitions

[0110] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the relevant terms and laboratory procedures used herein are terms and conventional procedures widely used in the corresponding fields. At the same time, in order to better understand the present invention, the definitions and explanations of the relevant terms are provided below.

[0111] As used herein and unless otherwise specified, the term "about" or "approximately" means within plus or minus 10% of a given value or range. Where an integer is required, the term means within plus or minus 10% of a given value or range, rounded up or down to the nearest integer.

[0112] In the description of this document, reference is made to “some embodiments”, “some implementation schemes” or “some implementation plans”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0113] As used herein and unless otherwise specified, the terms "comprising", "including", "having", "containing", including grammatical equivalents thereof, should generally be understood as open and non-limiting, for example, not excluding other unlisted elements or steps.

[0114] As used herein, the term "wt%" refers to the weight ratio and the proportion of a substance in a mixture. For example, 7.0-12.0 wt% of lanthanum (La) means that the weight proportion of La in the total weight of all elements in the alloy is 7.0-12.0 wt%.

[0115] As used herein, the term "aluminum alloy" refers to an alloy having aluminum as the base and a certain amount of other alloying elements added thereto.

[0116] As used herein, the term "Additive Manufacturing" (AM) refers to any process that produces a three-dimensional object and includes steps of sequentially forming the shape of an object one layer at a time. For example, AM processes include three-dimensional printing (3DP) processes, laser net shaping manufacturing, direct metal laser sintering (DMLS), direct metal laser melting (DMLM), free-form manufacturing, etc. AM processes, which are not limited to a specific type, use an energy beam, such as an electron beam or electromagnetic radiation, such as a laser beam to sinter or melt powder materials. AM processes can use metal powder materials or wires as raw materials. Additive manufacturing is a method of manufacturing physical objects from digital objects by adding materials layer by layer, and the thickness of each added layer is about tens or hundreds of microns.

[0117] As used herein, the term "Selective Laser Melting" (SLM) is a forming technology that uses a laser to directly heat metal powder to completely melt it and then cool it to form it. The laser beam quickly melts the metal powder and obtains a continuous melt path, which can directly obtain metal parts of almost any shape, complete metallurgical bonding, and high precision and nearly dense. The forming principle of SLM technology is: a layer of metal powder is spread on the substrate with a scraper, and then a laser beam is used under the control of a scanning galvanometer to quickly irradiate the powder along a certain path to melt it, solidify it, and form a metallurgical cladding layer. Then the substrate is lowered to the same height as the thickness of a single layer of deposition, and another layer of powder is spread for laser scanning processing. This process is repeated until the entire part is formed.

[0118] As used herein, the term "gas atomization powder making method" refers to a method in which a molten metal liquid is dispersed into small droplets by a high-speed gas flow and rapidly solidified into metal powder. The cooling rate can reach 10 4 -10 6K / s. During the process of gas atomization powder making, the metal droplets undergo a non-equilibrium solidification process at an extremely high cooling rate. The obtained powder structure morphology is related to the parameters in the gas atomization process, including factors such as temperature, gas properties and velocity, metal melt properties and droplet size. Liu et al. (LIUD, ZHAO J, YEH. Modeling of the solidification of gas-atomized alloy droplets during sprayforming [J]. Materials Science and Engineering: A, 2004, 372 (1-2): 229-34.) studied the solidification process of supercooled melt of Al-Cu alloy during gas atomization. When the droplet flight distance is long enough, the solidification of the droplet will go through five processes: liquid phase cooling, nucleation and recalescence, segregation solidification, eutectic solidification, and solid phase cooling. In the initial liquid phase cooling stage, the droplets cool rapidly and have the highest cooling rate during the heat exchange with the gas flow, and the cooling rate increases with the decrease of the droplet size. For large-sized droplets, the latent heat of solidification released during the nucleation process will increase the temperature, while the temperature rise of small-sized droplets is weaker than the heat loss caused by heat exchange. Therefore, the solidification time of small-sized droplets is much lower than that of large-sized powders. Zhai et al. (ZHAIQ J, GAO YL, GUAN WB, et al. Role of size and cooling rate in quenched droplet of SnBi eutectic alloy [J]. Materials Science and Engineering: A, 2006, 441 (1-2): 278-81.) studied the effects of droplet size and cooling rate on the microstructure of Sn-Bi eutectic alloy. It is difficult to observe the direct effect of the two on the microstructure. The change in microstructure is mainly related to the change in supercooling (the microstructure of the powder changes from "regular + irregular" to "completely irregular"). Among them, when the droplet size is reduced from 34μm to 20μm, the supercooling increases by 16.8K; while the cooling rate increases from 4.08×10 4 K / s increased to 1.23×10 5 When the temperature is lower than 2000 K / s, the supercooling degree only increases by 0.4 K. Obviously, the effect of droplet size on supercooling degree is more obvious. Therefore, the diameter of the powder also affects the microstructure of the powder prepared by gas atomization method.

[0119] II. Examples

[0120] The present invention is described in detail below through specific examples. It should be understood that the following examples are only for explanation and illustration and are not intended to limit the scope of the present invention in any form.

[0121] The raw materials and equipment used in the specific embodiments of the present disclosure are all known products, which are obtained by purchasing commercially available products.

[0122] Example 1

[0123] A high temperature resistant aluminum alloy powder for additive manufacturing, wherein the chemical composition of the aluminum alloy in the powder is w(La)=9.80%, w(Sc)=0.46%, w(Zr)=0.26%, and the balance is aluminum.

[0124] Preparation of aluminum alloy powder

[0125] The preparation method of the powder comprises the following steps:

[0126] (1) Melting of Al-La-Sc-Zr alloy prefabricated ingot:

[0127] a. Add high-purity Al, Al-La master alloy blocks, and Al-Zr master alloy blocks into a crucible and heat them in a resistance furnace to completely melt them at a melting temperature of 800°C. Then keep them at 850°C for 15 minutes. After keeping them warm, remove the scum on the surface;

[0128] b. Add Al-Sc master alloy block, stir the melt slightly to make it completely melted, cool the melt to 760℃, and keep it warm for 5 minutes;

[0129] c. Keep the melt temperature at 760℃, add refining agent and refine for 5min, then remove the surface scum. After refining, sprinkle the covering agent and vacuum degas for 10min, then remove the surface scum again, and when the melt temperature is measured at 740℃, cast and air cool to obtain Al-La-Sc-Zr alloy prefabricated ingot;

[0130] (2) Gas atomization forming of Al-La-Sc-Zr alloy powder:

[0131] a. After the Al-La-Sc-Zr alloy preform ingot is placed in a crucible in a gas atomization equipment melting chamber, the air in the melting chamber is replaced by nitrogen;

[0132] b. Heating by electromagnetic induction, with the target temperature being 800°C; keeping the temperature for 30 minutes to completely melt the prefabricated ingot.

[0133] c. The melt flows out along the nozzle under the action of gravity and is broken into droplets of different sizes under the impact of fast-moving atomized argon gas. The droplets solidify into powder during the falling process. The falling powder is collected at the bottom of the cavity and vacuum packaged.

[0134] Experimental analysis and testing

[0135] The typical morphology of the Al-La-Sc-Zr alloy powder prepared in this embodiment is as follows: Figure 1 As shown. The powder particle size for additive manufacturing is 15 to 53 μm, and the sphericity is high. The Al-La-Sc-Zr alloy powder prepared in this embodiment is additively manufactured using a selective laser melting process to obtain a block material. The laser power used for additive manufacturing is 200W, the scanning speed is 1500mm / s, the scanning layer thickness is 30μm, the scanning spacing is 100μm, and the scanning method is layer-by-layer scanning with a rotation of 67 degrees. The printed block material has no cracks, and no large number of holes are observed, as shown in FIG. Figure 1 Its typical microscopic solidification grain structure and eutectic structure are shown in Figure 2 As shown in the figure, the grains are formed into a mixed structure of equiaxed crystals and columnar crystals, the size of equiaxed crystals is 1 to 5 μm, the size of columnar crystals is no more than 50 μm, and the Al-La eutectic structure is a typical submicron cellular structure. The printed Al-La-Sc-Zr alloy block was stretched at room temperature using a Zwick / Roell-Z100 tensile machine for 10 -3 s -1 The strain rate is uniaxially stretched, and the stretching direction is perpendicular to the printing direction. The stretching curve is as follows Figure 3 As shown, the tensile strength is measured to be 385 MPa, the yield strength is 303 MPa, and the elongation is 8.5%.

[0136] Example 2

[0137] The material composition of this embodiment is the same as that of the embodiment 1, and the experimental steps (1) and (2) are the same as those of the embodiment 1.

[0138] Experimental analysis and testing

[0139] This embodiment is basically the same as Embodiment 1, except that:

[0140] The printed Al-La-Sc-Zr alloy block was subjected to aging heat treatment at 325°C for 1 hour and then cooled in air. Uniaxial stretching was performed at room temperature using a Zwick / Roell-Z100 tensile machine according to GB / T228.1-2010 standard and at 300°C using a Zwick / Roell-Z005 tensile machine according to GB / T4338-2006 metal material high temperature tensile test standard. The sample was kept isothermally in a thermostat for 30 minutes before high temperature stretching. The room temperature and high temperature tensile strain rates were both 10 -3 s -1 , the stretching direction is perpendicular to the printing direction, and the stretching curve is as follows Figure 3As shown, the room temperature tensile strength is 453MPa, the yield strength is 413MPa, and the elongation is 7.5%. The high temperature tensile strength at 300°C is 251MPa, the yield strength is 230MPa, and the elongation is 5.0%.

[0141] After simple aging treatment, the Al-La-Sc-Zr alloy block in this embodiment has greatly improved strength compared to the printed state, showing the precipitation strengthening effect of the Al3 (Sc, Zr) nano-precipitate phase formed by heat treatment. In addition, the Al-La-Sc-Zr alloy block exhibits extremely excellent high-temperature strength, which is 45-50% higher than the yield strength of traditional heat-resistant aluminum alloys (ZL205, 2618) in the industry at the same temperature. The reason lies in the dual effects of load-bearing strengthening provided by the extremely fine submicron three-dimensional cellular network structure of the Al-La eutectic phase at high temperature and strengthening by Al3 (Sc, Zr) nanoparticles.

[0142] Example 3

[0143] The material composition of this embodiment is the same as that of the embodiment 1, and the experimental steps (1) and (2) are the same as those of the embodiment 1.

[0144] Experimental analysis and testing

[0145] This embodiment is basically the same as Embodiment 2, except that:

[0146] The laser power used in additive manufacturing is 200W and the scanning speed is 1800mm / s. The tensile curve is as follows Figure 4 As shown, the room temperature tensile strength is 451MPa, the yield strength is 423MPa, and the elongation is 4.7%. The high temperature tensile strength at 300°C is 228MPa, the yield strength is 217MPa, and the elongation is 7.0%.

[0147] Example 4

[0148] The material composition of this embodiment is the same as that of the embodiment 1, and the experimental steps (1) and (2) are the same as those of the embodiment 1.

[0149] Experimental analysis and testing

[0150] This embodiment is basically the same as Embodiment 2, except that:

[0151] The laser power used in additive manufacturing is 160W, the scanning speed is 1300mm / s, and the stretching curve is as follows Figure 5 As shown, the room temperature tensile strength is 457MPa, the yield strength is 415MPa, and the elongation is 4.4%. The high temperature tensile strength at 300°C is 248MPa, the yield strength is 229MPa, and the elongation is 6.6%.

[0152] Example 5

[0153] A high temperature resistant aluminum alloy powder for additive manufacturing, wherein the chemical composition of the aluminum alloy in the powder is w(La)=11.5%, w(Sc)=0.29%, w(Zr)=0.12%, and the balance is aluminum.

[0154] The experimental steps (1) and (2) are the same as those in Example 1.

[0155] Experimental analysis and testing

[0156] This embodiment is the same as embodiment 2. The tensile curve is as follows Figure 6 As shown, the room temperature tensile strength is 444MPa, the yield strength is 411MPa, and the elongation is 6.1%. The high temperature tensile strength at 300°C is 266MPa, the yield strength is 243MPa, and the elongation is 5.0%.

[0157] Example 6

[0158] A high temperature resistant aluminum alloy powder for additive manufacturing, wherein the chemical composition of the aluminum alloy in the powder is w(La)=9.10%, w(Sc)=0.61%, w(Zr)=0.75%, and the balance is aluminum.

[0159] The experimental steps (1) and (2) are the same as those in Example 1.

[0160] Experimental analysis and testing

[0161] This embodiment is basically the same as embodiment 2. The tensile curve is as follows Figure 7 As shown, the room temperature tensile strength is 461MPa, the yield strength is 416MPa, and the elongation is 7.1%. The high temperature tensile strength at 300°C is 231MPa, the yield strength is 215MPa, and the elongation is 7.0%.

[0162] Example 7

[0163] A high temperature resistant aluminum alloy powder for additive manufacturing, wherein the chemical composition of the aluminum alloy in the powder is w(La)=10.5%, w(Sc)=0.51%, w(Zr)=0.35%, w(Mg)=1.5%, w(Mn)=0.6%, and the balance is aluminum.

[0164] The experimental steps (1) and (2) are the same as those in Example 1.

[0165] Experimental analysis and testing

[0166] This embodiment is basically the same as embodiment 2, and its room temperature tensile strength is 481 MPa, yield strength is 425 MPa, and elongation is 6.1%. The high temperature tensile strength at 300°C is 255 MPa, yield strength is 235 MPa, and elongation is 6.2%.

[0167] The specific embodiments of the present invention are described in detail above, but they are only used as examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equal transformations and modifications made without departing from the spirit and scope of the present invention are all included in the scope of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.

Claims

1. A high temperature resistant aluminum alloy, characterized in that: The aluminum alloy comprises: 5.0-15.0 wt% of lanthanum (La), not more than 1.0 wt% of scandium (Sc), and not more than 1.0 wt% of zirconium (Zr); Optionally, less than or equal to 5 wt % of magnesium (Mg), less than or equal to 1 wt % of manganese (Mn).

2. The aluminum alloy according to claim 1, comprising: 7.0-12.0 wt% of lanthanum (La), preferably 7.0-9.5 wt%, or 9.5-11.0 wt%, or 11.0-12.0 wt%; Preferably, the aluminum alloy contains 0.1-1.0 wt% of scandium (Sc), preferably 0.1-0.3 wt%, or 0.3-0.5 wt%, or 0.5-0.7 wt%; Preferably, the aluminum alloy contains 0.1-1.0 wt% zirconium (Zr), preferably 0.1-0.2 wt%, or 0.2-0.4 wt%, or 0.6-0.8 wt%; Optionally, the aluminum alloy contains less than or equal to 2 wt % magnesium (Mg), preferably 1-2 wt %; Optionally, the aluminum alloy contains less than or equal to 0.6 wt % manganese (Mn), preferably 0.5-0.6 wt %; Preferably, the aluminum alloy comprises: 9.80wt% lanthanum, 0.46wt% scandium, and 0.26wt% zirconium; Preferably, the aluminum alloy comprises: 11.5wt% lanthanum, 0.29wt% scandium, and 0.12wt% zirconium; Preferably, the aluminum alloy comprises: 9.10wt% lanthanum, 0.61wt% scandium, and 0.75wt% zirconium; Preferably, the aluminum alloy comprises: 10.5 wt % lanthanum, 0.51 wt % scandium, 0.35 wt % zirconium, 1.5 wt % magnesium, and 0.6 wt % manganese.

3. The aluminum alloy according to claim 1 or 2, wherein: The aluminum alloy further contains aluminum (Al) and inevitable impurities as the balance; Preferably, the impurities include at least one of boron, titanium, silicon, chromium, vanadium, manganese, zinc, phosphorus, calcium, nickel, copper, cerium or lithium.

4. The aluminum alloy according to any one of claims 1 to 3, wherein: The aluminum alloy is manufactured in powder form; Preferably, the aluminum alloy in powder form is used in an additive manufacturing method; Preferably, the particle size of the aluminum alloy in powder form for additive manufacturing is 10-60 μm, preferably 15-53 μm.

5. The method for preparing the aluminum alloy according to claim 4, wherein: The method comprises the following steps: melting of alloy prefabricated ingots and gas atomization forming of alloy powders; Preferably, the smelting of the alloy prefabricated ingot comprises steps S1-S5, and the gas atomization forming of the alloy powder comprises steps S6-S8: S1. According to the weight ratio of the chemical components of the alloy, high-purity Al, Al-La master alloy block, Al-Sc master alloy block, and Al-Zr master alloy block are weighed as raw materials, and optionally, the raw materials also include high-purity Mg; S2, mixing Al and Al-La master alloy blocks, adding them into a crucible, placing them in a resistance furnace, heating and stirring until melt A is completely melted, and then keeping the temperature; S3, adding the Al-Sc master alloy block to the melt A, stirring slightly after it is completely melted to obtain melt B, and then keeping the temperature; S4, adding a refining agent to melt B for refining, and removing the surface scum; S5. After refining, a covering agent is sprinkled on the melt B for vacuum degassing, and the surface scum is removed again, and then casting and air cooling are performed to obtain a prefabricated ingot C; S6, after placing the prefabricated ingot C into the crucible in the melting chamber of the gas atomization equipment, the air in the melting chamber is replaced by nitrogen; S7, maintaining the prefabricated ingot C at the melting temperature by electromagnetic induction heating to completely melt the ingot; S8, using high-speed compressed argon gas to impact the aluminum alloy prefabricated ingot C melt, the high-speed gas causes the melt to break into tiny droplets, which solidify into tiny powders during the descent process, and collect and vacuum-pack them to obtain finished alloy powders; More preferably, the melting temperature in step S2 is 700-1000° C., more preferably 700-900° C.; More preferably, the insulation temperature in step S2 is 840-860° C., more preferably 845-855° C.; More preferably, the holding time of step S2 is 5-15 min, more preferably 10-15 min; More preferably, the insulation temperature in step S3 is 750-770° C., more preferably 755-765° C.; More preferably, the holding time in step S3 is 5-15 min, more preferably 5-10 min; More preferably, the refining time in step S4 is 5-10 min, more preferably 5 min; More preferably, the degassing time in step S5 is 10-20 min, more preferably 10-15 min; More preferably, the melt temperature during casting in step S5 is 740±5°C, more preferably 740°C; More preferably, the holding time of step S7 is 5-120 min, more preferably 20-40 min; More preferably, the smelting temperature in step S7 is not less than 800°C; More preferably, the purity of argon in step S8 is ≥ 99.999%.

6. Aluminum alloy block, which is prepared from the aluminum alloy in powder form according to claim 4; Preferably, the aluminum alloy block is prepared by additive manufacturing; Preferably, the preparation further comprises aging heat treatment; Preferably, the additive manufacturing includes one or more selected from the group consisting of selective laser melting additive manufacturing, laser directed energy deposition additive manufacturing, electron beam selective melting additive manufacturing, and electron beam directed energy deposition additive manufacturing; Preferably, the additive manufacturing is a selective laser melting process; Preferably, the scanning strategy of the selective laser melting additive manufacturing is strip scanning; Preferably, the scanning speed of the selective laser melting additive manufacturing is 1000-2000 mm / s, preferably 1300-1800 mm / s; Preferably, the laser power of the selective laser melting additive manufacturing is not higher than 220W, preferably 150-200W, more preferably 160-200W; Preferably, the scanning pitch of the selective laser melting additive manufacturing is 80-120 μm, more preferably 100 μm; Preferably, the scanning layer thickness of the selective laser melting additive manufacturing is 20-40 μm, more preferably 30 μm; Preferably, the scanning method of the selective laser melting additive manufacturing is layer-by-layer scanning with a rotation of 67 degrees; Preferably, the aging heat treatment comprises the following steps: performing aging heat treatment at 300-350°C for 30min-1h, followed by cooling in air; More preferably, the laser power of the selective laser melting additive manufacturing is 200W, the scanning speed is 1500mm / s, the scanning layer thickness is 30μm, the scanning interval is 100μm, and the scanning mode is layer-by-layer scanning with a rotation of 67 degrees; More preferably, the laser power of the selective laser melting additive manufacturing is 200W, the scanning speed is 1800mm / s, the scanning layer thickness is 30μm, the scanning interval is 100μm, and the scanning mode is layer-by-layer scanning with a rotation of 67 degrees; More preferably, the laser power of the selective laser melting additive manufacturing is 160 W, the scanning speed is 1300 mm / s, the scanning layer thickness is 30 μm, the scanning interval is 100 μm, and the scanning method is layer-by-layer scanning with a rotation of 67 degrees.

7. The aluminum alloy block according to claim 6, wherein: The aluminum alloy block meets at least one of the following conditions: (1) The aluminum alloy block can withstand a temperature of not less than 300°C; (2) The aluminum alloy block has no cracks; (3) The room temperature tensile strength of the aluminum alloy block is not less than 350 MPa; (4) The room temperature elongation of the aluminum alloy block is not less than 4%; (5) The room temperature yield strength of the aluminum alloy block is not less than 300 MPa; (6) The tensile strength of the aluminum alloy block at 300° C. is not less than 200 MPa; (7) The elongation of the aluminum alloy block at 300°C is not less than 5%; (8) The aluminum alloy block has a yield strength of not less than 200 MPa at 300°C; Preferably, the room temperature tensile strength of the aluminum alloy block is not less than 380 MPa; Preferably, the room temperature tensile strength of the aluminum alloy block is not less than 450 MPa; Preferably, the room temperature tensile strength of the aluminum alloy block is 350 MPa-500 MPa; Preferably, the room temperature elongation of the aluminum alloy block is not less than 7%; Preferably, the room temperature elongation of the aluminum alloy block is 4%-10%; Preferably, the room temperature yield strength of the aluminum alloy block is not less than 400 MPa; Preferably, the room temperature yield strength of the aluminum alloy block is 300 MPa-450 MPa; Preferably, the aluminum alloy block has a tensile strength of not less than 250 MPa at 300°C; Preferably, the aluminum alloy block has a tensile strength of 200 MPa-300 MPa at 300°C; Preferably, the aluminum alloy block has an elongation of 5%-10% at 300°C; Preferably, the aluminum alloy block has a yield strength of 200 MPa-250 MPa at 300°C.

8. The aluminum alloy block according to claim 6 or 7, wherein: The aluminum alloy block material has a grain structure of equiaxed crystals and columnar crystals; Preferably, the equiaxed crystal size is 1-5 μm; Preferably, the columnar crystal size is no greater than 50 μm; Preferably, the eutectic phase organization presents a submicron scale cellular network structure.

9. Use of the aluminum alloy according to any one of claims 1 to 4 or the aluminum alloy prepared by the method according to claim 5 in additive manufacturing.

10. Use of the aluminum alloy according to any one of claims 1 to 4, the aluminum alloy prepared by the method according to claim 5, or the aluminum alloy block according to any one of claims 6 to 8 in the preparation of aluminum alloy parts; Preferably, the aluminum alloy component is used in aerospace equipment, rail transportation equipment, automobiles or electronic products.

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