Aluminum alloy and preparation method thereof

Abstract

The invention provides an aluminum alloy and a preparation method thereof. The aluminum alloy comprises the following elements in percentage by mass: 12-16% of Ce element, 0.2-0.6% of Sc element, 0.4-0.8% of Zr element, less than or equal to 0.15% of inevitable impurities and the balance of Al element, wherein at the room temperature, the tensile strength of the aluminum alloy ranges from 500 MPa to 610 MPa, and the ductility ranges from 5% to 12%; at the temperature of 300 DEG C, the tensile strength of the aluminum alloy is 230-260 MPa, and the ductility is 8-15%; in the aluminum alloy, the mass content of an Al11Ce3 phase is 0.20%-0.28%, and the mass content of an Al3 (Sc, Zr) phase is 0.014%-0.020%. The aluminum alloy disclosed by the invention has excellent room-temperature mechanical properties and high-temperature mechanical properties, and can better meet the requirements of the aerospace field on the heat-resistant aluminum alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy, in particular to an aluminum alloy and a preparation method thereof. BACKGROUND

[0002] Aluminum alloy has the advantages of low density, high specific strength and excellent corrosion resistance, and is widely used in aerospace and shipbuilding fields. However, the mechanical properties of aluminum alloy at room temperature and high temperature are still insufficient, especially in the aerospace industry, as the aircraft design develops towards higher performance and more complex structure, higher requirements are put forward for the mechanical properties of aluminum alloy. The processing methods of aluminum alloy such as casting and forging can produce aluminum alloy components, but there are limitations in the manufacture of complex geometry, and it is difficult to fine-tune the microstructure of the alloy to optimize its mechanical properties at high temperature.

[0003] Additive manufacturing technology (3D printing technology) is a technology that uses metal powder to build objects by layer-by-layer stacking. Compared with traditional metal processing technology, 3D printing technology can realize rapid manufacturing of high-performance complex components, saving a lot of material and time cost. In the field of metal 3D printing technology, laser powder bed fusion is one of the technologies widely used at present. However, in order to achieve the density of 3D printed workpieces, the aluminum alloy system of 3D printing usually needs to have good melt flowability, which limits the design of the current 3D printed aluminum alloy system, and also limits the strength of the 3D printed aluminum alloy system. Especially for heat-resistant aluminum alloy system, which is usually designed based on low-strength cast heat-resistant aluminum alloy system, the mechanical properties of aluminum alloy at room temperature and high temperature are both poor. Therefore, it is urgent to develop a heat-resistant aluminum alloy based on 3D printing, which has excellent mechanical properties at room temperature and high temperature. SUMMARY

[0004] The main purpose of the present application is to provide an aluminum alloy and a preparation method thereof, to solve the problem that the aluminum alloy in the prior art has poor mechanical properties at room temperature and high temperature.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an aluminum alloy is provided, which comprises the following elements in mass percentage: 12-16% of Ce element, 0.2-0.6% of Sc element, 0.4-0.8% of Zr element, the total content of unavoidable impurities ≤0.15%, and the balance of Al element; wherein at room temperature, the tensile strength of the aluminum alloy is 500-610 MPa, and the elongation of the aluminum alloy is 5-12%; at 300℃, the tensile strength of the aluminum alloy is 230-260 MPa, and the elongation of the aluminum alloy is 8-15%; the Al 11The mass content of the Ce3 phase is 0.20-0.28%; and the mass content of the Al3(Sc, Zr) phase in the aluminum alloy is 0.014-0.020%.

[0006] Further, the aluminum alloy contains, in mass percentage, 13-15% of Ce, 0.3-0.5% of Sc, 0.4-0.8% of Zr, and ≤0.15% of unavoidable impurities, with the balance being Al.

[0007] Further, the mass ratio of the Sc element to the Zr element is 0.375-1.2:1.

[0008] Further, the average grain size of the aluminum alloy is 1-2 μm; and / or, the Al 11 The thickness of the Ce3 phase is 40-160 nm; and / or, the density of the aluminum alloy is >99%.

[0009] According to another aspect of the present application, there is provided a preparation method of the aluminum alloy, which comprises: step S1, sequentially subjecting raw materials comprising pure Al ingot, Al-Ce intermediate alloy, Al-Sc intermediate alloy and Al-Zr intermediate alloy to melting and gas atomization powdering to obtain alloy powder; and step S2, subjecting the alloy powder to 3D printing to obtain the aluminum alloy.

[0010] Further, in the step S1, the mass content of the Ce element in the Al-Ce intermediate alloy is 30-50%; the mass content of the Sc element in the Al-Sc intermediate alloy is 5-20%; and the mass content of the Zr element in the Al-Zr intermediate alloy is 5-20%.

[0011] Further, in the step S1, the gas atmosphere for melting is argon, the temperature for melting is 740-760 °C, and the time for melting is 8-12 min.

[0012] Further, the step S1 further comprises: sieving after the gas atomization powdering in the argon atmosphere to obtain the alloy powder; wherein the gas pressure for the gas atomization powdering is 1.5-2.5 MPa, and the temperature for the gas atomization powdering is 740-760 °C; and the particle size of the alloy powder is 10-100 μm.

[0013] Further, in the step S2, the 3D printing is performed by laser powder bed fusion, and the conditions for the 3D printing include: laser power of 200-400 W, scanning speed of 1000-2000 mm / s, scanning interval of 100-200 μm, powder layer thickness of 20-40 μm, preheating temperature of 150-200 °C, and bulk energy density of 30-150 J / mm 3 , and the interlayer angle is 45°-90°.

[0014] Further, the step S2 further comprises: sequentially performing 3D printing and aging treatment on the alloy powder to obtain the aluminum alloy; wherein the temperature of the aging treatment is 250-350 DEG C, and the time of the aging treatment is 12-36 h.

[0015] By applying the technical scheme of the present application, the present application proposes a design scheme of a hypereutectic Al-Ce heat-resistant alloy, which expands the design concept of the Al-Ce alloy. By adding Sc elements and Zr elements and increasing the content of the Ce element in the above range, the microstructure of the aluminum alloy can be significantly refined, thereby improving the density of the aluminum alloy, and the tensile strength and elongation of the aluminum alloy at room temperature and at a high temperature of 300 DEG C reach the above range. Specifically, the addition of the Ce element in the above content can form a high-temperature strengthening phase Al 11 Ce3 phase that stably exists at a high temperature, thereby achieving high-temperature strengthening. When the content of the Ce element is too low, the content of the Ce element for forming the Al 11 Ce3 phase is insufficient, thereby resulting in insufficient high-temperature strength of the aluminum alloy. Therefore, the controlled content of the Ce element can make the Al 11 Ce3 phase have the mass content in the above range, thereby further simultaneously improving the room-temperature mechanical properties and high-temperature mechanical properties of the aluminum alloy. The addition of the Sc element and the Zr element can form the Al3(Sc,Zr) phase with the above mass content during solidification as a heterogeneous nucleation site, thereby reducing the pores and cracks generated during solidification. At the same time, the Sc-Zr element is segregated at the interface between the Al-Ce intermediate phase and the matrix Al, which can further improve the heat resistance of the aluminum alloy. In summary, the aluminum alloy of the present application has excellent room-temperature mechanical properties and high-temperature mechanical properties, and can better meet the requirements of the aerospace field for heat-resistant aluminum alloys. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. In the drawings:

[0017] Figure 1 An optical microscope graph of the aluminum alloy in Example 1 of the present application is shown;

[0018] Figure 2 An organizational morphology graph of the aluminum alloy in Example 1 of the present application is shown;

[0019] Figure 3 A tensile curve comparison graph of the aluminum alloy in Example 13 of the present application at room temperature and at 300 DEG C is shown. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0021] As analyzed in the background of the present application, the aluminum alloy in the prior art has the problem of poor room temperature mechanical properties and high temperature mechanical properties. In order to solve the above problems, the present application provides an aluminum alloy and a preparation method thereof.

[0022] In a typical embodiment of the present application, an aluminum alloy is provided, which comprises the following elements in mass percentage: 12-16% of Ce element, 0.2-0.6% of Sc element, 0.4-0.8% of Zr element, the total content of inevitable impurities is ≤0.15%, and the balance is Al element; wherein at room temperature, the tensile strength of the aluminum alloy is 500-610 MPa, and the elongation of the aluminum alloy is 5-12%; at 300℃, the tensile strength of the aluminum alloy is 230-260 MPa, and the elongation of the aluminum alloy is 8-15%; the Al 11 The mass content of the Ce3 phase is 0.20-0.28%, and the mass content of the Al3(Sc, Zr) phase in the aluminum alloy is 0.014-0.020%.

[0023] The present application proposes a design scheme of hypereutectic Al-Ce heat-resistant alloy, which expands the design concept of Al-Ce alloy. By adding Sc element and Zr element and increasing the content of Ce element in the above range, the microstructure of the aluminum alloy can be significantly refined, thereby improving the density of the aluminum alloy, and the tensile strength and elongation of the aluminum alloy at room temperature and at high temperature of 300℃ reach the above range. Specifically, the addition of the above content of Ce element can form a high-temperature strengthening phase Al 11 Ce3 phase which exists stably at high temperature, and can realize high-temperature strengthening. When the content of Ce element is too low, the content of Ce element for forming the Al 11 Ce3 phase is insufficient, thereby resulting in insufficient high-temperature strength of the aluminum alloy. Therefore, the content of Ce element in the present application can make the Al 11 Ce3 phase, thereby further improving the room temperature mechanical properties and high temperature mechanical properties of the aluminum alloy. The addition of Sc element and Zr element can form the Al3(Sc, Zr) phase with the above mass content as a heterogeneous nucleation site during solidification, thereby reducing the pores and cracks generated during solidification. At the same time, the Sc-Zr element is segregated at the interface between the Al-Ce intermediate phase and the matrix Al, which can further improve the heat resistance of the aluminum alloy. In summary, the aluminum alloy of the present application has excellent room temperature mechanical properties and high temperature mechanical properties, and can better meet the requirements of the aerospace field for heat-resistant aluminum alloys.

[0024] In order to further improve the mechanical properties of the aluminum alloy at room temperature and high temperature, in an embodiment of the present application, the aluminum alloy contains, in mass percentage, 13-15% of Ce, 0.3-0.5% of Sc, 0.4-0.8% of Zr, and unavoidable impurities with a total content of ≤0.15%, and the balance being Al.

[0025] Preferably, the aluminum alloy contains Al 11 The mass ratio of the Ce3 phase and the Al3(Sc, Zr) phase is 12-17:1, which helps to improve the synergistic effect of the two phases, thereby further improving the mechanical properties of the aluminum alloy at room temperature and high temperature, and also helps to reduce the formation of pores and cracks, thereby further improving the density and overall performance of the aluminum alloy.

[0026] In an embodiment of the present application, the mass ratio of Sc and Zr is 0.375-1.2:1, preferably 0.6-1.0:1.

[0027] Preferably, the mass ratio of Sc and Zr is controlled within the above range, which helps to increase the heterogeneous nucleation sites, refine the grain structure, reduce the pores and cracks in the printed part, and thereby improve the density and mechanical properties of the aluminum alloy. At the same time, it is also beneficial to form the Al3(Sc, Zr) phase, thereby further improving the mechanical properties and thermal stability of the aluminum alloy at room temperature and high temperature.

[0028] In an embodiment of the present application, the average grain size of the aluminum alloy is 1-2 μm; and / or, the aluminum alloy has a density of >99%, preferably 99.1-99.7%. 11 The thickness of the Ce3 phase is 40-160 nm; and / or, the density of the aluminum alloy is >99%, preferably 99.1-99.7%.

[0029] Preferably, the average grain size of the aluminum alloy is within the above range, which helps to improve the strength and thermal stability of the aluminum alloy. Preferably, the average grain size of the aluminum alloy is 1-2 μm. 11 The thickness of the Ce3 phase is within the above range, which helps to further strengthen the high-temperature strengthening effect. The density is an important indicator of the degree of internal porosity and defects of the material. Preferably, the density of the aluminum alloy is within the above range, which helps to reduce internal porosity and micro-cracks, thereby improving the overall uniformity and consistency of the aluminum alloy, and further improving the strength of the aluminum alloy.

[0030] In another typical embodiment of the present application, a preparation method of the above-mentioned aluminum alloy is provided, which comprises: step S1, sequentially melting and gas-atomizing raw materials including pure Al ingot, Al-Ce intermediate alloy, Al-Sc intermediate alloy, and Al-Zr intermediate alloy to obtain alloy powder; and step S2, 3D printing the alloy powder to obtain the aluminum alloy.

[0031] The aluminum alloy obtained by the preparation method has excellent room temperature mechanical properties and high temperature mechanical properties, thereby better meeting the requirements of the aerospace field for heat-resistant aluminum alloys. Specifically, in step S1, the molten aluminum alloy is converted into powder by gas atomization after being melted by the above raw materials. Gas atomization generally uses high-pressure gas to be sprayed into the molten metal, so that it rapidly solidifies into fine powder particles, thereby obtaining alloy powder with uniform particle size distribution. Generally, heat-resistant Al-Ce alloys are mainly obtained by casting, and the strength thereof is generally low. However, the 3D printing technology used in the present application can significantly refine the microstructure of the alloy due to its unique rapid cooling forming process, thereby simultaneously improving the room temperature strength and high temperature strength of the aluminum alloy. In addition, the composite alloying of Sc and Zr elements in the aluminum alloy causes the Al-Ce hypereutectic alloy to first form a large number of Al3(Sc, Zr) particles during the 3D printing solidification process, thereby reducing the pores and cracks of the printed alloy during the solidification process, and refining the printed structure. In summary, the preparation method of the present application can significantly refine the microstructure of the aluminum alloy, thereby simultaneously improving the mechanical properties of the aluminum alloy at room temperature and at high temperature of 300℃.

[0032] In order to obtain an aluminum alloy with uniform element composition distribution, in an embodiment of the present application, in the above step S1, the mass content of the Ce element in the Al-Ce intermediate alloy is 30-50%; the mass content of the Sc element in the Al-Sc intermediate alloy is 5-20%; and the mass content of the Zr element in the Al-Zr intermediate alloy is 5-20%.

[0033] In an embodiment of the present application, in the above step S1, the atmosphere for melting is argon, the temperature for melting is 740-760℃, preferably 745-755℃, and the time for melting is 8-12 min, preferably 9-11 min.

[0034] The argon (Ar) atmosphere used in the melting process as a protective gas helps to provide a clean and stable melting environment, thereby improving the purity of the material. The temperature and time for melting are preferably in the above range, which helps the above alloy elements to be fully dissolved in the aluminum matrix to form a uniform alloy liquid, thereby providing good raw materials for subsequent gas atomization powdering.

[0035] In an embodiment of the present application, the above step S1 further comprises: sieving after gas atomization powdering in an argon atmosphere to obtain alloy powder; wherein the gas pressure for gas atomization powdering is 1.5-2.5 MPa, and the temperature for gas atomization powdering is 740-760℃; the particle size of the alloy powder is 10-100 μm, preferably 30-80 μm.

[0036] The gas pressure for gas atomization is preferably in the above range, which helps to break the alloy liquid into powder particles in size and morphology. The temperature for gas atomization is preferably in the above range, which helps to carry out gas atomization, fully utilize the flowability and temperature characteristics of the alloy liquid, and form uniform and fine powder particles. The particle size of the alloy powder after sieving is preferably in the above range, which helps to make the alloy powder have good flowability and help to achieve high-quality 3D printing, while facilitating subsequent sieving to remove oversized or undersized powder particles to improve the uniformity of 3D printing and the precision of the aluminum alloy.

[0037] In an embodiment of the present application, in the step S2, the 3D printing method is laser powder bed fusion, and the 3D printing conditions include: the laser power is 200-400 W, preferably 250-350 W, more preferably 280-320 W, the scanning speed is 1000-2000 mm / s, the scanning interval is 100-200 μm, preferably 120-160 μm, the powder layer thickness is 20-40 μm, the preheating temperature is 150-200 °C, and the bulk energy density is 30-150 J / mm 3 , and the interlayer angle is 45°-90°.

[0038] The process of laser powder bed fusion is as follows: 1) Powder preparation and spreading The alloy powder is spread on the printing platform, and the powder layer thickness is controlled.

[0039] 2) Laser scanning and melting Laser scanning: the laser moves according to the pre-designed slice file (i.e. the two-dimensional cross section of the three-dimensional model) path under computer control, irradiating the selected powder layer area. When the laser irradiates the powder, the powder absorbs the laser energy and quickly heats up to above the melting point, forming a liquid metal. As the laser moves, the liquid metal cools and solidifies, forming the required metal layer. This process is repeated until all the powder layers are melted and solidified.

[0040] 3) Interlayer processing Re-spreading: after completing the melting and solidification of each layer, the printing platform moves down by a layer thickness, and then a new layer of powder is spread, and the laser continues to scan and melt the next layer. In order to reduce the anisotropy in the printed structure and improve the strength and rigidity of the aluminum alloy, the direction of laser scanning will be changed between each layer, i.e. the interlayer angle is controlled.

[0041] Preferably, the laser power is in the above range, which helps to improve the melting effect, thereby improving the density and surface quality of the aluminum alloy. Preferably, the scanning speed is in the above range, which helps to improve the printing speed while ensuring that the alloy powder is fully melted to form a uniform and dense structure. Preferably, the scanning pitch is in the above range, which helps to improve the melting depth and quality while taking into account the printing efficiency. Preferably, the powder layer thickness is in the above range, which helps to better bond the layers and improve the surface quality of the aluminum alloy. Preferably, the preheating temperature is in the above range, which helps to reduce thermal stress and cracks generated during printing. Preferably, the bulk energy density is in the above range, which helps to fully melt the alloy powder while maintaining an appropriate cooling rate, thereby forming a dense and uniform structure. Preferably, the layer-to-layer angle (the angle between the laser scanning direction after each powder laying and the scanning direction of the previous layer) is in the above range, which helps to form a certain angle between the laser scanning direction and the previous layer during the printing of the subsequent layer, thereby helping to uniformly distribute the material and reduce anisotropy.

[0042] In an embodiment of the present application, the step S2 further comprises sequentially 3D printing and aging treatment of the alloy powder to obtain the aluminum alloy; wherein the aging treatment temperature is 250-350℃, preferably 275-325℃, and the aging treatment time is 12-36h, preferably 18-30h.

[0043] Through the aging treatment, controlling the temperature and time of the aging treatment in the above range helps to precipitate a large number of Al3(Sc,Zr) particles in the Al matrix, which works together with the 3D printing to simultaneously improve the strength of the aluminum alloy at room temperature and high temperature.

[0044] The beneficial effects of the present application will be further illustrated in conjunction with the embodiments below.

[0045] Embodiment 1 According to the composition of 14% Ce element, 0.4% Sc element, 0.6% Zr element and the balance Al element, the aluminum alloy raw material pure Al ingot, Al-Ce intermediate alloy (the mass content of Ce element is 30%), Al-Sc intermediate alloy (the mass content of Sc element is 5%) and Al-Zr intermediate alloy (the mass content of Zr element is 10%) are prepared, melted, and the molten alloy is heated to 750℃ and kept for 10min. Then, under the argon atmosphere at 750℃, the gas pressure is 2MPa, and the powder is prepared by gas atomization. After cooling, the powder is collected and sieved to obtain alloy powder with a particle size of 15-53μm.

[0046] The alloy powder is prepared into a block-shaped aluminum alloy with a length, width and height of 100 mm by laser powder bed fusion 3D printing. The 3D printing conditions are as follows: the laser power is 300 W, the scanning speed is 1400 mm / s, the scanning interval is 130 μm, the powder layer thickness is 30 μm, the substrate is preheated to 180 ℃, and the input bulk energy density during the 3D printing process is 54.9 J / mm 3 After each powder laying, the angle between the laser scanning direction and the previous scanning direction (interlayer angle) is 67°. After printing, the aluminum alloy is aged at 300 ℃ for 24 h.

[0047] Example 2 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 13% Ce element, 0.3% Sc element, 0.4% Zr element and the balance of Al element by mass percentage, and finally the aluminum alloy is obtained.

[0048] Example 3 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 16% Ce element, 0.6% Sc element, 0.8% Zr element and the balance of Al element by mass percentage, and finally the aluminum alloy is obtained.

[0049] Example 4 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 12% Ce element, 0.2% Sc element, 0.4% Zr element and the balance of Al element by mass percentage, and finally the aluminum alloy is obtained.

[0050] Example 5 The difference from Example 1 is that the total mass of Sc element and Zr element is 1%, and the mass ratio of Sc element to Zr element is 1.2:1, and finally the aluminum alloy is obtained.

[0051] Example 6 The difference from Example 1 is that the total mass of Sc element and Zr element is 1%, and the mass ratio of Sc element to Zr element is 1.5:1, and finally the aluminum alloy is obtained.

[0052] Example 7 The difference from Example 1 is that the mass of Al 11 The mass ratio of Ce3 phase to Al3(Sc,Zr) phase is 0.27:0.016.

[0053] Example 8 The difference from Example 1 is that the mass of Al 11 The mass ratio of Ce3 phase to Al3(Sc,Zr) phase is 0.27:0.014.

[0054] Example 9 The difference from Example 1 is that the 3D printing conditions are as follows: the laser power is 200 W, the scanning speed is 1000 mm / s, the scanning interval is 100 μm, the powder layer thickness is 20 μm, the substrate is preheated to 150 °C, and the bulk energy density input during the 3D printing process is 30 J / mm 3 , the angle between the laser scanning direction after each powder laying and the last scanning direction (interlayer angle) is 45°, and finally an aluminum alloy is obtained.

[0055] Example 10 The difference from Example 1 is that the 3D printing conditions are as follows: the laser power is 450 W, the scanning speed is 2500 mm / s, the scanning interval is 250 μm, the powder layer thickness is 50 μm, the substrate is preheated to 250 °C, and the bulk energy density input during the 3D printing process is 160 J / mm 3 , the angle between the laser scanning direction after each powder laying and the last scanning direction (interlayer angle) is 35°, and finally an aluminum alloy is obtained.

[0056] Example 11 The difference from Example 1 is that the gas pressure for gas atomization powdering is 1.5 MPa, the temperature for gas atomization powdering is 740 °C, and finally an aluminum alloy is obtained.

[0057] Example 12 The difference from Example 1 is that the gas pressure for gas atomization powdering is 3 MPa, the temperature for gas atomization powdering is 760 °C, and finally an aluminum alloy is obtained.

[0058] Example 13 The difference from Example 1 is that the alloy powder is subjected to aging treatment after 3D printing to obtain an aluminum alloy; wherein the aging treatment temperature is 275 °C, and the aging treatment time is 24 h.

[0059] Example 14 The difference from Example 1 is that the alloy powder is subjected to aging treatment after 3D printing to obtain an aluminum alloy; wherein the aging treatment temperature is 400 °C, and the aging treatment time is 10 h.

[0060] Comparative Example 1 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 14% Ce element and the balance of Al element in mass percentage.

[0061] The 3D printing conditions are as follows: the laser power is 350 W, the scanning speed is 1000 mm / s, the scanning interval is 250 μm, and the bulk energy density input during the 3D printing process is 77.8 J / mm 3 , and finally an aluminum alloy is obtained.

[0062] Comparative Example 2 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 14% of Ce element, 0.6% of Zr element and the balance of Al element by mass percentage, and finally an aluminum alloy is obtained.

[0063] Comparative Example 3 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 8% of Ce element, 0.4% of Sc element, 0.6% of Zr element and the balance of Al element by mass percentage, and finally an aluminum alloy is obtained.

[0064] Comparative Example 4 The difference from Example 1 is that the aluminum alloy raw material is compounded according to the composition of 3% of Mn element, 0.2% of Mg element, 0.1% of Ni element, 0.5% of Ce element, 0.8% of Sc element, 0.2% of Zr element and the balance of Al element by mass percentage, and finally an aluminum alloy is obtained.

[0065] Comparative Example 5 The difference from Example 1 is that the alloy powder is obtained by spray forming, and finally an aluminum alloy is obtained.

[0066] Test method: Room temperature (25℃) and high temperature tensile test: the aluminum alloy sample in heat treated state is processed into standard tensile test sample meeting the requirements of GB / T228.1-2010 by using electric spark wire cutting, and electronic universal testing machine is used to test the room temperature (25℃) and high temperature tensile test of each sample.

[0067] Al in aluminum alloy 11 Mass content test of Ce3 phase and Al3(Sc, Zr) phase: SEM phase morphology combined with energy spectrum and micrograph analysis is used to obtain area fraction conversion to mass content.

[0068] Al 11 Thickness test of Ce3 phase: thin film sample is prepared by electrolysis or FIB method, and it is ensured that the intercepted area contains Al 11 Ce3 phase / matrix interface. Al 11 Ce3 phase thickness (thickness along the shortest direction of the phase or perpendicular to the interface), record thickness distribution and calculate average value and standard deviation.

[0069] Density test: after polishing, light etching is necessary to show the pores. Optical microscope or SEM is used to take pictures under multiple random / systematic fields, the resolution is enough to identify the smallest pores, and the area fraction of pores is calculated.

[0070] The above test results are shown in Table 1 and Table 2.

[0071] Table 1

[0072] Table 2

[0073] From the above results, it can be seen that, due to the low content of rare earth Ce in Comparative Example 4, it is difficult to form continuous, fine and stable distribution of Al 11 Ce3 phase strengthening phase, resulting in coarse structure, high porosity, and significant decrease in overall density and mechanical properties of the alloy. The phase organization of Comparative Example 5 is severely coarsened, and the density is low, which shows that the alloy is prone to produce coarse eutectic phase and shrinkage defects under this process condition, and there are many microcracks and pores in the material. It can be seen that, due to the unreasonable content of rare earth and process parameters in Comparative Example 4 and Comparative Example 5, the strengthening phase is coarse and the porosity increases, which significantly weakens the comprehensive performance of the aluminum alloy material.

[0074] wherein, Figure 1 is the optical microscope image of the aluminum alloy in Example 1, from which Figure 1 it can be seen that the Al-Ce intermetallic phase organization in the aluminum alloy is extremely fine, providing extremely high strengthening effect for the aluminum alloy.

[0075] Figure 2 is the microstructure morphology diagram of the aluminum alloy in Example 1, from which Figure 2 it can be seen that the printed aluminum alloy has fewer holes and higher density, and the density of the aluminum alloy is 99.5% through image analysis.

[0076] Figure 3 shows the tensile curve comparison diagram of the aluminum alloy in Example 13 of the application at room temperature and 300 DEG C, from which Figure 3 it can be seen that the tensile strength at room temperature 25 DEG C is high, reaching about 510 MPa; and at 300 DEG C high temperature, the tensile strength still remains about 250 MPa, indicating that the aluminum alloy of the application has excellent high temperature mechanical properties and thermal stability, and the high temperature strength retention rate is more than 48%, showing excellent heat-resistant strengthening effect, which can meet the structural application requirements in high temperature service environment.

[0077] From the above description, it can be seen that the above-mentioned embodiments of the application achieve the following technical effects: The application provides a design scheme of a hypereutectic Al-Ce heat-resistant alloy, and expands the design concept of the Al-Ce alloy. By adding Sc elements and Zr elements and increasing the content of the Ce element in the above range, the microstructure of the aluminum alloy can be refined, the density of the aluminum alloy is improved, and the tensile strength and elongation of the aluminum alloy at room temperature and at a high temperature of 300 DEG C are in the above range. Specifically, the addition of the Ce element in the above content can form a high-temperature strengthening phase Al 11 Ce3 phase which can exist stably at a high temperature, and high-temperature strengthening can be realized. When the content of the Ce element is too low, the content of the Ce element for forming the Al 11 Ce3 phase is insufficient, and thus the high-temperature strength of the aluminum alloy is insufficient. Therefore, the application controls the content of the Ce element, so that the Al 11 Ce3 phase has the mass content in the above range, and thus the room-temperature mechanical properties and the high-temperature mechanical properties of the aluminum alloy are further improved simultaneously. The addition of the Sc element and the Zr element can form the Al3(Sc,Zr) phase with the above mass content during solidification as a heterogeneous nucleation site, so that the pores and cracks generated during solidification are reduced. Meanwhile, the Sc-Zr elements are segregated at the interface between the Al-Ce intermediate phase and the matrix Al, and the heat resistance of the aluminum alloy can be further improved. In summary, the aluminum alloy of the application has excellent room-temperature mechanical properties and high-temperature mechanical properties, and can better meet the requirements of the aerospace field for heat-resistant aluminum alloys.

[0078] The above is only an embodiment of the application and is not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An aluminum alloy, characterized in that, The aluminum alloy comprises, by mass percentage, the following elements: 12-16% Ce, 0.2-0.6% Sc, 0.4-0.8% Zr, total unavoidable impurities ≤0.15%, and the balance being Al. At room temperature, the tensile strength of the aluminum alloy is 500~610MPa, and the elongation of the aluminum alloy is 5~12%. At 300℃, the tensile strength of the aluminum alloy is 230~260MPa, and the elongation of the aluminum alloy is 8~15%. Al in aluminum alloy 11 The mass content of Ce3 phase is 0.20~0.28%; the mass content of Al3(Sc,Zr) phase in the aluminum alloy is 0.014~0.020%.

2. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy comprises, by mass percentage, the following elements: 13-15% Ce, 0.3-0.5% Sc, 0.4-0.8% Zr, ≤0.15% total unavoidable impurities, and the balance being Al.

3. The aluminum alloy according to claim 1, characterized in that, The mass ratio of the Sc element to the Zr element is 0.375~1.2:

1.

4. The aluminum alloy according to any one of claims 1 to 3, characterized in that, The average grain size of the aluminum alloy is 1~2μm; and / or, the Al 11 The thickness of the Ce3 phase is 40~160 nm; and / or, the density of the aluminum alloy is >99%.

5. A method for preparing the aluminum alloy according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1 involves sequentially melting and gas-atomizing raw materials, including pure Al ingots, Al-Ce master alloys, Al-Sc master alloys, and Al-Zr master alloys, to obtain alloy powder; and Step S2: 3D print the alloy powder to obtain the aluminum alloy.

6. The preparation method according to claim 5, characterized in that, In step S1, the mass content of Ce in the Al-Ce master alloy is 30-50%; the mass content of Sc in the Al-Sc master alloy is 5-20%; and the mass content of Zr in the Al-Zr master alloy is 5-20%.

7. The preparation method according to claim 5, characterized in that, In step S1, the melting atmosphere is argon, the melting temperature is 740~760℃, and the melting time is 8~12min.

8. The preparation method according to any one of claims 5 to 7, characterized in that, Step S1 further includes: performing the gas atomization powder preparation in an argon atmosphere and then sieving to obtain the alloy powder; wherein the gas pressure of the gas atomization powder preparation is 1.5~2.5MPa, the temperature of the gas atomization powder preparation is 740~760℃, and the particle size of the alloy powder is 10~100μm.

9. The preparation method according to any one of claims 5 to 7, characterized in that, In step S2, the 3D printing method is laser powder bed melting. The 3D printing conditions include: laser power of 200~400W, scanning speed of 1000~2000mm / s, scanning spacing of 100~200μm, powder bed thickness of 20~40μm, preheating temperature of 150~200℃, and volume energy density of 30~150J / mm². 3 The interlayer turning angle is 45°~90°.

10. The preparation method according to any one of claims 5 to 7, characterized in that, Step S2 further includes: sequentially performing 3D printing and aging treatment on the alloy powder to obtain the aluminum alloy; wherein the aging treatment temperature is 250~350℃ and the aging treatment time is 12~36h.

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