Laser additive manufacturing high-toughness heat-resistant aluminum alloy and preparation method thereof

Abstract

The invention relates to the technical field of additive manufacturing, and provides a laser additive manufacturing high-toughness heat-resistant aluminum alloy and a preparation method thereof.The aluminum alloy is prepared through the laser additive technology and comprises Fe, Ni, Cr, Ti and Al; the aluminum alloy comprises the following components in percentage by mass: 0.5-2wt.% of Fe, less than 4.5 wt.% of the sum of the content of Fe and Ni, more than 2wt.% of Cr, 4-9wt.% of the sum of the content of Cr and Ti, and the balance of aluminum. According to the invention, Fe, Ni, Cr and Ti are introduced into an aluminum matrix, and specific extreme rapid non-equilibrium solidification conditions of laser additive are combined, so that an aluminum alloy part which is low in cost, good in printability, wide in forming process window, low in metallurgical defect, high in density, excellent in room-temperature and high-temperature mechanical properties, high in strength, high in toughness and high in thermal stability is obtained; the method can be widely applied to the fields of aerospace, rail transit, automobile industry and the like.

Description

Technical Field

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

[0002] Aluminum alloys are widely used in application fields with strict weight requirements due to their high specific strength, excellent corrosion resistance, thermal and electrical conductivity, workability, economic and environmental friendliness and other excellent properties. In particular, in the aerospace field, lightweight and high-strength structural materials are of great significance for improving the performance of aircraft and reducing energy consumption. As a lightweight metal material that can maintain excellent properties at high temperatures (250-350°C), heat-resistant aluminum alloys are gradually showing their potential and broad development prospects as an alternative to existing high-cost heat-resistant titanium alloys.

[0003] At present, most of the components in the low-temperature section (250-350°C) of aero-engines are prepared from cast aluminum alloys. For example, engine parts such as casings and housings that work short-term or long-term at 250-350°C are prepared by using ZL206 alloy through sand casting process. Reports show that the room-temperature tensile strength of cast heat-resistant aluminum alloys is about 290-370 MPa, and the elongation is only 1.5%-2%; the high-temperature tensile strength at 250-300°C is about 240-320 MPa, and the elongation is about 4%-6%. Thus, it can be seen that the room-temperature / high-temperature strength and elongation of traditional cast heat-resistant aluminum alloys are both low, and it is imperative to develop new heat-resistant aluminum alloys. In addition, the dimensional accuracy and shape control requirements of complex-shaped, hollow and thin-walled parts are high, and even with precision casting processes, there are still great difficulties, and it is impossible to guarantee the product quality and its stability. Therefore, traditional cast heat-resistant aluminum alloys and their casting processes are difficult to meet the requirements of future advanced aero-engines for lightweight, heat-resistant, high-performance, lightweight, high-reliability and complex-structured parts, and it is urgent to develop high-strength, tough and heat-resistant aluminum alloy materials for additive manufacturing.

[0004] In terms of additive manufacturing materials, at present, the types and quantities of heat-resistant aluminum alloys suitable for additive manufacturing technology are still small. On the one hand, currently, the commercial aluminum alloy powders available for additive manufacturing are mainly Al-Si series alloys and Al-Mg-Sc-Zr (Scalmalloy®) alloys, which have good printability and excellent room-temperature mechanical properties. However, the rapid coarsening and decomposition of their strengthening phases at high temperatures lead to a sharp drop in strength. For example, the decomposition of the Al-Si eutectic network and the coarsening of Si particles result in the service temperature of Al-Si series alloys not exceeding 200°C, while the coarsening of the Al3(Sc, Zr) precipitation phase at the grain boundaries limits the service temperature of Al-Mg-Sc-Zr alloys not exceeding 300°C. On the other hand, traditional Al-Cu series heat-resistant aluminum alloys have a wide solidification range and are prone to forming columnar dendrites under the rapid heating and cooling solidification conditions of laser additive manufacturing, with a high cracking tendency and poor printability. Therefore, it is necessary to develop a new type of high-strength and tough heat-resistant aluminum alloy for additive manufacturing to make up for the deficiencies of the existing technology. Summary of the Invention

[0005] The present invention provides a laser additive manufacturing high-strength and tough heat-resistant aluminum alloy and a preparation method thereof. By adding transition metal elements with low diffusion coefficients such as Fe, Ni, Cr, and Ti to the aluminum matrix and precisely controlling the element content, a high-strength and tough heat-resistant aluminum alloy with low defects in additive manufacturing is achieved, with a room-temperature tensile strength ≥ 452 MPa, an elongation after fracture ≥ 10%, a 300°C tensile strength ≥ 235 MPa, and an elongation after fracture ≥ 11%, balancing cost and printability.

[0006] Specifically, in the first aspect, the present invention provides an aluminum alloy prepared by laser additive technology, and its components include Fe, Ni, Cr, Ti, and Al; by mass percentage, in the aluminum alloy, the Fe content is 0.5 wt.% to 2 wt.%, the sum of the Fe and Ni contents is below 4.5 wt.%, the Cr content is above 2 wt.%, the sum of the Cr and Ti contents is 4 to 9 wt.%, and the balance is aluminum.

[0007] According to the aluminum alloy provided by the present invention, by mass percentage, the Fe content is 0.7 wt.% to 2 wt.%, preferably 0.7 to 1.8 wt.%; further preferably, by mass percentage, the Fe content can be any point value or a range composed of any point values among 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, and 1.8 wt.%.

[0008] For the aluminum alloy provided by the present invention, by mass percentage, the content of Ni is 0.1 to 3 wt.%, preferably 0.1 to 0.9 wt.%; further preferably, by mass percentage, the content of Ni can be any point value among 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.% and 0.9 wt.% or a range composed of any point values.

[0009] For the aluminum alloy provided by the present invention, by mass percentage, the content of Cr is 2 to 6.5 wt.%, preferably 2 to 5 wt.%; further preferably, by mass percentage, the content of Cr can be any point value among 2.0 wt.%, 2.1 wt.%, 2.2 wt.%, 2.3 wt.%, 2.4 wt.%, 2.5 wt.%, 2.6 wt.%, 2.7 wt.%, 2.8 wt.%, 2.9 wt.%, 3.0 wt.%, 3.1 wt.%, 3.2 wt.%, 3.3 wt.%, 3.4 wt.%, 3.5 wt.%, 3.6 wt.%, 3.7 wt.%, 3.8 wt.%, 3.9 wt.%, 4.0 wt.%, 4.1 wt.%, 4.2 wt.%, 4.3 wt.%, 4.4 wt.%, 4.5 wt.%, 4.6 wt.%, 4.7 wt.%, 4.8 wt.%, 4.9 wt.% and 5.0 wt.% or a range composed of any point values.

[0010] For the aluminum alloy provided by the present invention, by mass percentage, the content of Ti is 1 to 5.5 wt.%, preferably 2 to 4.5 wt.%. Further preferably, by mass percentage, the content of Ti can be any point value among 2.0 wt.%, 2.1 wt.%, 2.2 wt.%, 2.3 wt.%, 2.4 wt.%, 2.5 wt.%, 2.6 wt.%, 2.7 wt.%, 2.8 wt.%, 2.9 wt.%, 3.0 wt.%, 3.1 wt.%, 3.2 wt.%, 3.3 wt.%, 3.4 wt.%, 3.5 wt.%, 3.6 wt.%, 3.7 wt.%, 3.8 wt.%, 3.9 wt.%, 4.0 wt.%, 4.1 wt.%, 4.2 wt.%, 4.3 wt.%, 4.4 wt.% and 4.5 wt.% or a range composed of any point values.

[0011] For the aluminum alloy provided by the present invention, by mass percentage, the sum of the contents of Fe and Ni is above 0.6 wt.%, preferably 0.8 to 2.4 wt.%.

[0012] For the aluminum alloy provided by the present invention, the sum of the Cr and Ti contents is 4 to 8 wt.% by mass percentage.

[0013] For the aluminum alloy provided by the present invention, the microstructure of the aluminum alloy includes: a micron-sized equiaxed grain structure, micron-sized precipitates, nano-sized precipitates, and a eutectic network.

[0014] For the aluminum alloy provided by the present invention, the size range of the micron-sized equiaxed grain structure is 0.5 to 4 μm.

[0015] For the aluminum alloy provided by the present invention, the micron-sized precipitates include massive Al3Ti, which are distributed at the melt pool boundary, and the size range is 0.3 to 2 μm.

[0016] For the aluminum alloy provided by the present invention, the nano-sized precipitates include spherical Al3Ti, quasicrystalline phases, and Al 13 (Fe,Cr) 4,2 , which are distributed inside the melt pool, and the size range is 50 to 400 nm.

[0017] For the aluminum alloy provided by the present invention, the eutectic network includes α-Al and Al6Fe / Al3Ni, which are distributed inside the melt pool.

[0018] By adding transition metal elements such as Fe, Ni, Cr, and Ti with low diffusion coefficients in the aluminum matrix under high-temperature conditions, and simultaneously controlling the contents of each element within the above ranges, a multi-scale heterogeneous hierarchical microstructure is obtained under the extremely rapid non-equilibrium solidification conditions unique to laser additive manufacturing, including a micron-sized equiaxed grain structure, a large number of dispersed and thermally stable micron- and nano-sized second-phase precipitates (Al-Fe-Cr icosahedral quasicrystalline phase and its variant Al 13 (Fe,Cr) 4,2 phase, Al3Ti phase), and Al6Fe / Al3Ni eutectic network, effectively improving the room-temperature and high-temperature mechanical properties of the aluminum alloy. In addition, the Ti element significantly refines the aluminum alloy grains through mechanisms such as constitutional supercooling, heterogeneous nucleation, grain boundary pinning, and inhibition of recrystallization, which helps to reduce the hot cracking tendency of the material. The multi-scale heterogeneous microstructure helps to synergistically improve the strength and plasticity of the material, solving the problems of low plasticity, easy cracking, and poor printability of traditional heat-resistant aluminum alloys.

[0019] The as-cast aluminum alloy has a relative density exceeding 99.5%, an average hardness of 140 to 163 HV 0.2 , a room-temperature tensile strength ≥ 452 MPa, and an elongation after fracture ≥ 10%; a 300°C tensile strength ≥ 235 MPa, and an elongation after fracture ≥ 11%.

[0020] Second aspect, the present invention provides a method for preparing the aluminum alloy, comprising: performing additive forming on the aluminum alloy powder by using a laser powder bed fusion technique; The composition of the aluminum alloy powder includes: Fe, Ni, Cr, Ti and Al; by mass percentage, in the aluminum alloy powder, the Fe content is 0.5wt.% to 2wt.%, the sum of the Fe and Ni contents is below 4.5wt.%, the Cr content is above 2wt.%, the sum of the Cr and Ti contents is 4 to 9wt.%, and the balance is aluminum.

[0021] According to the method for preparing the aluminum alloy provided by the present invention, the particle size distribution of the aluminum alloy powder is 15 to 53μm, and the median particle size is 22 to 35μm.

[0022] The method for preparing the aluminum alloy powder includes: Formulating raw materials into a mixture, and melting the mixture under vacuum conditions to obtain a pre-alloyed metal; Atomizing the pre-alloyed metal under the protection of a rare gas to obtain pre-alloyed metal powder; Screening and drying the pre-alloyed metal powder under an inert gas protection atmosphere to obtain the aluminum alloy powder.

[0023] Preferably, the raw materials include pure metals of component elements and / or intermediate alloys of component elements. As an example: the raw materials can be pure Al, Al-Fe alloy, Al-Ni alloy, Al-Cr alloy, Al-Ti alloy.

[0024] Preferably, the melting temperature is 1150 to 1300°C, and the melting time is 10 to 30 minutes; further preferably, the melting temperature is 1150 to 1200°C.

[0025] Preferably, the atomizing air pressure is 0.5 to 8MPa; further preferably, the atomizing air pressure is 0.5 to 5MPa.

[0026] Preferably, the drying temperature is 80 to 120°C, and the drying time is 2 to 5 hours.

[0027] According to the method for preparing the aluminum alloy provided by the present invention, the process parameters of the additive forming include: the substrate preheating temperature is 20 to 80°C, the laser power is 200 to 400W, the scanning speed is 500 to 1500mm / s, the scanning layer thickness is 0.02 to 0.06mm, the scanning spacing is 0.06 to 0.16mm, and the rotation angle between adjacent layers is 0 to 90º.

[0028] Preferably, the process parameters of the additive manufacturing include: laser power: 250 - 400 W, scanning speed: 1000 - 1500 mm / s, rotation angle between adjacent layers: 0 - 70º.

[0029] The functions of the above alloying elements in the material will be described in detail below.

[0030] Functions of Fe and Ni elements: Under the conditions of non-equilibrium rapid solidification in laser additive manufacturing, α-Al and Al6Fe / Al3Ni eutectic structures are formed, which helps to narrow the solidification temperature range of the alloy, thereby effectively compensating for the thermal crack defects between grains. Due to the low diffusion coefficients of Fe and Ni in the aluminum matrix, the coarsening rate of the intermetallic compounds Al6Fe and Al3Ni at high temperatures is low, and they have excellent thermal stability. However, when the Fe content increases, the fluidity of the alloy will decrease, and the solidification temperature range will expand, resulting in an increased tendency for hot cracking. In addition, in the molten pool boundary region, due to the relatively low cooling rate, the coarsened Al 13 Fe4 phase with its inherent brittle characteristics is prone to initiate interlayer cracks and significantly reduce the plasticity of the material. Experiments have found that when the Fe content increases to more than 2 wt.%, the plasticity decreases significantly, and when the Fe content increases to more than 5 wt.%, significantly exceeding the eutectic composition, it will lead to severe cracking and unable to be formed.

[0031] Functions of Cr element: On the one hand, it can form some strengthening phases of intermetallic compounds with high melting points, high hardness and good thermal stability, such as Al 11 Cr2, Al 13 Cr2, Al7Cr; on the other hand, under the conditions of extremely fast cooling and non-equilibrium solidification in laser additive manufacturing, a high volume fraction of nanoscale Al-Fe-Cr icosahedral quasicrystalline phase and its variant Al 13 (Fe,Cr) 4,2 phase are formed. The crystallization temperature of the Al-Fe-Cr quasicrystalline phase is as high as 450°C and has excellent thermal stability. The Cr-rich strengthening / quasicrystalline phase can not only effectively hinder the movement of dislocations and thus improve the strength of the material, but also hinder the migration of grain boundaries and the growth of grains by pinning the grain boundaries, maintaining the thermal stability of the grain boundaries. In addition, its oxide Cr2O3 has high chemical stability and can protect the grain boundaries from corrosion, thereby improving the chemical stability of the grain boundaries.

[0032] Function of Ti element: When adding Ti element to aluminum alloy, the segregation of Ti will change the solute distribution at the solidification front, increase the constitutional supercooling degree, thus promoting nucleation and refining grains. The fine-grained structure can not only effectively reduce the hot cracking tendency of aluminum alloy, but also significantly improve the strength of the material through the fine-grain strengthening mechanism. In addition, the high-melting-point intermetallic compound Al3Ti preferentially formed in the initial stage of solidification has a high lattice matching degree with the aluminum matrix, can serve as the core of heterogeneous nucleation, significantly increase the nucleation rate, and further refine grains. At the same time, the Al3Ti precipitation phase can inhibit the recrystallization and grain growth processes of the alloy at high temperatures by pinning dislocations and (sub) grain boundaries, thereby improving the thermal stability of the material. In addition, due to the slow diffusion rate of Ti element in the aluminum matrix, it can effectively inhibit the coarsening of the Al3Ti strengthening phase at high temperatures and maintain its strengthening effect.

[0033] The Al-Fe-Ni-Cr-Ti multi-scale heterogeneous structure heat-resistant aluminum alloy prepared by the laser additive manufacturing high-strength and tough heat-resistant aluminum alloy and its preparation method provided by the present invention has low cost, good printability in laser additive manufacturing, wide forming process window, low metallurgical defects, high density, excellent mechanical properties at room temperature and high temperature, both high strength and high toughness, and high thermal stability. It is one of the aluminum alloys with the best matching of room temperature and high temperature strength and plasticity among the low-cost heat-resistant aluminum alloys reported so far, and can be widely used in the fields of aerospace, rail transit, automotive industry, etc. Brief Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is the morphology diagram of the aluminum alloy powder prepared in Example 1 of the present invention.

[0036] Figure 2 It is the metallographic diagram of the high-strength and tough heat-resistant aluminum alloy in Example 1 of the present invention.

[0037] Figure 3 It is the EBSD scanning image of the high-strength and tough heat-resistant aluminum alloy in Example 1 of the present invention.

[0038] Figure 4 It is the backscattered electron image of the high-strength and tough heat-resistant aluminum alloy in Example 1 of the present invention.

[0039] Figure 5 It is the XRD diagram of the high-strength and tough heat-resistant aluminum alloy in Example 1 of the present invention.

[0040] Figure 6 The TEM dark-field image and Fe element distribution map of the high-strength, tough and heat-resistant aluminum alloy in Example 1 of the present invention.

[0041] Figure 7 The metallographic structure diagram of the aluminum alloy in Comparative Example 1 of the present invention. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without any creative efforts shall fall within the protection scope of the present invention.

[0043] The following combines Figures 1 to 6 to describe a method for preparing a high-strength, tough and heat-resistant aluminum alloy by laser additive manufacturing and the preparation method thereof.

[0044] For those not specified in the embodiments regarding specific technologies or conditions, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For the reagents or instruments not specified for the manufacturers, they are all conventional products that can be obtained through regular channels.

[0045] Example 1 This example provides a method for preparing a high-strength, tough and heat-resistant aluminum alloy with multi-scale heterogeneous structure by laser additive manufacturing. The steps are as follows: (1) According to the elemental composition of the aluminum alloy, raw materials of pure Al, Al-Fe alloy, Al-Ni alloy, Al-Cr alloy and Al-Ti alloy are heated and melted under vacuum conditions. The melting temperature is 1150 °C and the melting time is 30 minutes. Then, 99.999% high-purity argon gas is used as the medium to atomize the melted metal droplets after melting, and the atomization pressure is 4 MPa to obtain pre-alloyed metal powder.

[0046] Among them, by mass percentage, the elemental composition of the aluminum alloy is Fe: 1 wt.%, Ni: 0.1 wt.%, Cr: 4 wt.%, Ti: 3 wt.%, and the balance is aluminum.

[0047] (2) The prepared pre-alloyed metal powder is subjected to screening and classification treatment under an argon protection atmosphere to obtain powder with a particle size range of 15 - 53 μm and a median particle size of 33 μm, and is placed in a vacuum at 100 °C for drying for 4 hours. After the drying treatment, aluminum alloy powder is obtained.

[0048] (3) Selective laser melting forming is carried out on the prepared aluminum alloy powder. The selective laser melting forming process is as follows: substrate preheating temperature: 20°C, laser power: 370 W, scanning speed: 1400 mm / s, scanning layer thickness: 0.03 mm, scanning spacing: 0.11 mm, rotation angle between adjacent layers: 67°.

[0049] Examples 2 - 6 For the preparation methods of the above laser additive manufactured multi-scale heterogeneous structure high-strength and tough heat-resistant aluminum alloys provided in Examples 2 - 6, the steps are basically the same as those in Example 1, except for the elemental composition of the aluminum alloy and its corresponding process parameters. By mass percentage, the elemental composition of the aluminum alloy is as shown in Table 1 below, and the process parameters are specifically as shown in Table 2 below.

[0050] Table 1

[0051] Table 2

[0052] Comparative Examples 1 - 3 A preparation method of an aluminum alloy provided in Comparative Examples 1 - 3 is basically the same as that in Example 1, except that: by mass percentage, the elemental composition of the aluminum alloy is as shown in Table 3 below.

[0053] Table 3

[0054] Among them, it was found during the preparation process that: the Fe content in Comparative Example 2 is too high, the fluidity of the alloy is significantly reduced, the solidification temperature range is expanded, the hot cracking tendency is increased, and the intermetallic compound Al 13 Fe4 with high hardness and brittleness precipitates first at the molten pool boundary, causing interlayer cracking.

[0055] Performance tests were carried out on the aluminum alloy specimens prepared in Examples 1 - 6, Comparative Example 1, and Comparative Example 3, and the test methods were GB / T 4340.1 - 2024 Metallic materials - Vickers hardness test - Part 1: Test method, GB / T 228.1 - 2021 Metallic materials - Tensile testing - Part 1: Method of test at room temperature, GB / T 228.2 - 2015 Metallic materials - Tensile testing - Part 2: High temperature test method. The test results are shown in Table 4.

[0056] Table 4

[0057] It can be seen from Example 1, Example 3, and Comparative Example 1 that when the Fe content increases, the strength of the alloy is improved to a certain extent, but the plasticity decreases significantly.

[0058] Furthermore, the Al-Fe-Ni-Cr-Ti multi-scale heterogeneous structure heat-resistant aluminum alloy sample prepared in Example 1 was characterized, and the characterization results are as follows Figures 1 to 5 shown

[0059] It can be seen from Figure 2 that the sample is dense and crack-free, with few metallurgical defects, indicating good formability

[0060] It can be seen from Figure 3 that the sample shows an equiaxed grain structure with an average grain size of 1.9 ± 0.8 μm

[0061] It can be seen from Figure 4 that the sample shows precipitation of second phases at the micron and nanometer scales. Micron-sized massive Al3Ti precipitates are distributed at the melt pool boundary, and nanometer-sized spherical precipitates are distributed inside the melt pool

[0062] It can be seen from Figure 5 that the sample mainly consists of an FCC aluminum matrix, Al3Ti with L12 and D0 22 structures, a quasicrystalline phase and its variant Al 13 (Fe,Cr) 4,2 composition

[0063] It can be seen from Figure 6 that the sample shows an Al-Fe eutectic structure

[0064] According to further analysis of the sample in Example 1, the micron-sized precipitates are massive Al3Ti, distributed at the melt pool boundary, with a size range of 0.3 - 2 μm; the nanometer-sized precipitates are spherical Al3Ti, the quasicrystalline phase and Al 13 (Fe,Cr) 4,2 , uniformly distributed inside the melt pool, with a size range of 50 - 400 nm; α-Al and the Al6Fe / Al3Ni eutectic network are distributed inside the melt pool

[0065] The aluminum alloy sample prepared in Comparative Example 1 was characterized, and the characterization results are as follows Figure 7 shown. It can be seen from Figure 7 that the sample has interlayer cracks

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention

Claims

1. An aluminum alloy prepared by laser additive manufacturing technology, characterized in that, Its components include Fe, Ni, Cr, Ti and Al; by mass percentage, in the aluminum alloy, the Fe content is 0.5 wt.% to 2 wt.%, the sum of the Fe and Ni contents is below 4.5 wt.%, the Cr content is 2 wt.% or more, the sum of the Cr and Ti contents is 4 to 9 wt.%, and the balance is aluminum.

2. The aluminum alloy according to claim 1, wherein By mass percentage, the content of Fe is 0.7 wt.% to 2 wt.%, preferably 0.7 to 1.8 wt.%; and / or, the content of Ni is 0.1 to 3 wt.%, preferably 0.1 to 0.9 wt.%; and / or, the content of Cr is 2 to 6.5 wt.%, preferably 2 to 5 wt.%; and / or, the content of Ti is 1 to 5.5 wt.%, preferably 2 to 4.5 wt.%.

3. The aluminum alloy according to claim 1 or 2, characterized in that, By mass percentage, the sum of the Fe and Ni contents is 0.6 wt.% or more, preferably 0.8 to 2.4 wt.%.

4. The aluminum alloy according to any one of claims 1 to 3, characterized in that, By mass percentage, the sum of the Cr and Ti contents is 4 to 8 wt.%.

5. The aluminum alloy according to any one of claims 1 to 4, characterized in that The microstructure of the aluminum alloy includes: a micron-sized equiaxed grain structure, micron-sized precipitates, nano-sized precipitates and eutectic networks.

6. The aluminum alloy according to claim 5, characterized in that, The size range of the micron-sized equiaxed grain structure is 0.5 to 4 μm.

7. The aluminum alloy according to claim 5 or 6, characterized in that, The micron-sized precipitates include massive Al3Ti, which are distributed at the melt pool boundary, and the size range is 0.3 to 2 μm; And / or, the nanoscale precipitation phases include spherical Al3Ti, quasicrystalline phases, and Al 13 (Fe, Cr) 4,2 , which are distributed inside the molten pool and have a size range of 50 to 400 nm; and / or, the eutectic network includes α-Al and Al6Fe / Al3Ni, which are distributed inside the melt pool.

8. The preparation method of the aluminum alloy according to any one of claims 1 to 7, characterized in that, Including: Using the laser powder bed fusion technology to perform additive manufacturing on the aluminum alloy powder; The components of the aluminum alloy powder include: Fe, Ni, Cr, Ti and Al; By mass percentage, in the aluminum alloy powder, the Fe content is 0.5 wt.% to 2 wt.%, the sum of the Fe and Ni contents is below 4.5 wt.%, the Cr content is 2 wt.% or more, the sum of the Cr and Ti contents is 4 to 9 wt.%, and the balance is aluminum.

9. The preparation method of the aluminum alloy according to claim 8, wherein, The particle size distribution of the aluminum alloy powder is 15 to 53 μm, and the median particle size is 22 to 35 μm.

10. The preparation method of the aluminum alloy according to claim 8 or 9, characterized in that, The process parameters of the additive manufacturing include: the substrate preheating temperature is 20 to 80 °C, the laser power is 200 to 400 W, the scanning speed is 500 to 1500 mm / s, the scanning layer thickness is 0.02 to 0.06 mm, the scanning spacing is 0.06 to 0.16 mm, and the rotation angle between adjacent layers is 0 to 90º.

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