An aluminum alloy powder for additive manufacturing, its preparation method and application

Abstract

The present invention relates to the field of additive manufacturing technology, and specifically provides an aluminum alloy powder for additive manufacturing, its preparation method and application. The aim is to solve the problems that existing aluminum alloys are prone to creep, thermal fatigue and thermal cracks under high-temperature environments. The aluminum alloy powder is composed of the following elements by mass fraction: Si 7.0 - 9.0%, Mg 3.5 - 5.5%, Y 1.0 - 2.0%, Mo 1.5 - 2.5%, Ti 1.5 - 2.5%, Fe 0.5 - 1.5%, and the balance is Al. By adding elements Y and Mo, stable strengthening phases are formed, improving the high-temperature creep resistance and thermal fatigue resistance of the alloy. The addition of element Ti further refines the grains and enhances the mechanical properties of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to an aluminum alloy powder that can be used for additive manufacturing, and a preparation method and application thereof. Background Art

[0002] Additive Manufacturing (AM), often referred to as 3D printing, is an advanced manufacturing technology that manufactures parts by adding materials layer by layer. In recent years, AM has been widely used in many industries, especially in aerospace, automotive, medical and precision manufacturing. Compared with traditional subtractive manufacturing technology, AM can directly build complex three-dimensional structures based on digital models, which has significant advantages, such as reducing material waste, shortening production cycles, and increasing design freedom.

[0003] In additive manufacturing, aluminum alloy has become one of the important materials due to its light weight, good mechanical properties and relatively low cost. However, in high temperature environments, aluminum alloy materials often face some inherent technical problems, especially in high temperature and severe cold alternating working environments such as aviation and rail transportation. These problems limit the widespread application of aluminum alloy materials.

[0004] When aluminum alloys are in service for a long time at high temperatures, especially in environments above 400°C, they usually experience significant creep. Creep is a plastic deformation process that occurs over time and is usually more significant at high temperatures. Creep not only reduces the strength of aluminum alloys, but may also cause structural failure. In additive manufacturing, the rapid cooling of each layer usually leads to uneven temperature gradients in the printed parts, exacerbating thermal stress and creep problems. Secondly, aluminum alloys will experience thermal fatigue under high temperature conditions, especially in long-term high-temperature cycle environments, and then thermal cracks will occur. Traditional aluminum alloys often lack the necessary toughness and resistance to thermal cracks in high-temperature environments, resulting in the easy breakage and damage of additively manufactured aluminum alloy parts during service. The formation of high-temperature fatigue and thermal cracks, especially in the fields of aviation, aerospace, rail transportation, etc., may have a fatal impact on the reliability of the structure. In the additive manufacturing process of aluminum alloys, the quality of the powder directly affects the performance of the printed parts. Existing aluminum alloy powder preparation methods, such as gas atomization, can better control the particle size, but often cannot effectively ensure the uniform distribution of different alloying elements. This compositional inhomogeneity will lead to a significant reduction in the mechanical properties, high temperature resistance and stability of the printed parts, especially in high temperature environments.

[0005] Although the prior art has made some improvements to the above problems, such as improving the creep resistance and high-temperature strength of aluminum alloys by adding reinforcing phases (such as SiC, AlSc, TiC, etc.) or improving their high-temperature fatigue performance by optimizing alloy compositions, the existing technologies still have the following deficiencies: 1. Most of the existing aluminum alloy powder strengthening schemes adopt a single strengthening mechanism, such as single particle strengthening, solid solution strengthening, etc. Although these schemes improve the performance of aluminum alloys to a certain extent, the strengthening effect is limited under high-temperature service, especially in extreme temperature and long-term high-temperature environments, and it is still difficult to meet the requirements of long-term stability at high temperatures. 2. Most of the existing technologies only solve one aspect of the problem, such as improving the high-temperature strength or fatigue resistance of aluminum alloys, and lack the comprehensive optimization of multiple high-temperature properties such as creep, thermal cracks, and fatigue. This makes the reliability and stability of additive manufacturing aluminum alloy materials poor in actual high-temperature environments. 3. Although some technologies adopt the strategy of adding multiple alloy elements, during the powder preparation process, especially during gas atomization, the alloy elements often fail to be evenly distributed. The non-uniformity of the composition results in the inability to obtain the desired mechanical properties of aluminum alloys during 3D printing, affecting their stability in high-temperature environments.

[0006] How to solve the problems such as high-temperature creep of aluminum alloys encountered in additive manufacturing has become one of the technical problems that need to be solved urgently. Summary of the Invention

[0007] In view of this, the present invention proposes a technical solution with a more reasonable alloy composition, which can solve problems such as high-temperature creep of aluminum alloy powder encountered in additive manufacturing to a certain extent.

[0008] The technical solution of the present invention is implemented as follows: The present invention provides an aluminum alloy powder for additive manufacturing, which includes the following components by mass fraction: Si: 7.0 - 9.0 wt%, Mg: 3.5 - 5.5 wt%, Y: 1.0 - 2.0 wt%, Mo: 1.5 - 2.5 wt%, Ti: 1.5 - 2.5 wt%, Fe: 0.5 - 1.5%, and the balance is Al.

[0009] In additive manufacturing, due to the rapid cooling of each layer, the aluminum alloy printed parts are prone to uneven temperature gradients, which leads to the accumulation of thermal stress, thereby increasing the risk of creep and thermal cracks. When traditional aluminum alloys are in high-temperature service, especially in an environment above 400 °C, creep will occur significantly, affecting the strength and stability of the structure. In the above solution, a multi-element alloy design is adopted, and a multiple strengthening design using elements such as Si, Mg, Y, Mo, Ti, and Fe is used. These elements have good mechanical properties and high-temperature creep resistance at high temperatures.

[0010] Specifically, by adding yttrium (Y) and molybdenum (Mo) elements, the creep resistance of aluminum alloy is improved. Yttrium can promote the stability of the precipitation phases in aluminum alloy, forming fine Al3Y strengthening phases. These fine and stable precipitation phases can effectively hinder grain slip, thereby enhancing the creep resistance of aluminum alloy at high temperatures. Molybdenum can increase the high-temperature strength of aluminum alloy. It can improve the solution strengthening effect of aluminum alloy and enhance the creep resistance at high temperatures. The combination of multiple alloying elements enhances the comprehensive performance of aluminum alloy, rather than the application of a single strengthening mechanism. Through the combination of these elements, the creep ability of aluminum alloy at high temperatures is improved, avoiding the problem of rapid degradation of traditional aluminum alloys in high-temperature environments. The addition of elements such as molybdenum (Mo) and yttrium (Y) can also form strengthening phases, further improving the creep resistance of aluminum alloy. In additive manufacturing, the use of these strengthening phases can effectively prevent the creep of aluminum alloy at high temperatures, especially when subjected to long-term load.

[0011] Molybdenum is dissolved in the aluminum matrix as an alloying element, causing lattice distortion, thereby increasing the strength of the alloy. After forming strengthening phases such as MoAl 12 etc., it plays a role in hindering dislocation movement in the matrix, further increasing the high-temperature strength and creep resistance of the alloy.

[0012] By precisely controlling the content of each element, adverse interactions that may occur between elements are avoided. For example, too high an Fe content may form brittle Al6Fe phases, affecting the ductility of the material. The optimization of element content ensures that stable strengthening phases precipitate in the alloy at high temperatures, rather than forming harmful intermetallic compounds.

[0013] In some embodiments, the composition includes the following mass fractions: Si: 8.0 wt%, Mg: 4.5 wt%, Y: 1.5 wt%, Mo: 2.0 wt%, Ti: 2.0 wt%, Fe: 1.0%, and the balance is Al.

[0014] In some embodiments, the aluminum alloy powder includes ultra-fine powder, fine powder, medium powder, and coarse powder. Among them, the particle size of the ultra-fine powder is <10 μm, the particle size of the fine powder is 10 - 50 μm, the particle size of the medium powder is 50 - 100 μm, and the particle size of the coarse powder is 100 - 150 μm.

[0015] In some embodiments, in the aluminum alloy powder, the proportion of ultra-fine powder is 10 - 15 wt%, the proportion of fine powder is 40 - 50 wt%, the proportion of medium powder is 25 - 30 wt%, and the proportion of coarse powder is 10 - 15 wt%.

[0016] This refined and hierarchical powder design helps reduce stress concentration inside the material during rapid cooling and lower the probability of thermal crack generation. Ultrafine powders (<10μm) and fine powders (10 - 50μm) have good fluidity and can be more evenly distributed during the printing process, reducing local uneven solidification that may be caused by large particles, thereby avoiding thermal cracks. The addition of titanium (Ti) and molybdenum (Mo) can not only improve the strength of the alloy but also enhance its fatigue resistance. These elements enhance the alloy's ability to resist fatigue crack propagation by forming stable precipitation phases. Under long-term high-temperature cyclic action, it can effectively delay the generation and propagation of fatigue cracks. The addition of yttrium (Y) and titanium (Ti) elements can improve the material's resistance to thermal cracks. In particular, the addition of yttrium can strengthen the toughness of the alloy at high temperatures and inhibit crack formation. Titanium helps improve the thermal fatigue performance of aluminum alloys by improving the grain boundary structure of the metal and enhancing resistance to thermal cracks.

[0017] The second aspect of the present invention lies in providing a method for preparing the above aluminum alloy powder, comprising the following steps:

[0018] Step 1: Select high-purity aluminum ingots and raw materials in the form of metals or alloys of other metal elements. According to the ratio, put them into a furnace and melt under a protective atmosphere. Control the melting temperature at 750 - 820°C and the melting time at 1 - 2h to ensure that all alloy elements are completely melted and form a uniform alloy liquid;

[0019] Step 2: Spray the molten alloy liquid through a high-pressure gas stream to rapidly cool and form powders;

[0020] Step 3: Remove the surface oxides of the powders by hydrogen reduction, and then anneal the powders at 180 - 250°C for 2 - 3h and perform aging treatment at 350 - 400°C for 6 - 8h.

[0021] In some embodiments, the high-pressure gas stream uses nitrogen or argon, and / or the flow rate of the high-pressure gas stream is 60 - 100L / min, and / or the pressure of the high-pressure gas stream is 4 - 5MPa, and / or the cooling rate is 2000 - 3000°C / s.

[0022] Adjust the gas stream parameters to control the degree of fragmentation of the metal liquid flow, so as to obtain the desired powder particle size distribution. A high cooling rate helps form fine and uniform powder particles and prevent segregation of alloy elements.

[0023] The third aspect of the present invention also lies in providing an application based on the above aluminum alloy powder, including applications in the fields of 3D printing, thermal spraying, cold spraying, butt welding, cladding, powder metallurgy, and powder forging.

[0024] The present invention has the following beneficial effects compared with the prior art:

[0025] The present invention conducts comprehensive design through multi-element strengthening, including yttrium, molybdenum, titanium, etc., as well as powder particle size control and optimization of powder composition uniformity, and effectively solves problems such as high-temperature creep, thermal cracks, and fatigue. Such multi-dimensional optimization measures can systematically improve the high-temperature performance of aluminum alloys during additive manufacturing, especially their stability and reliability under extreme temperature conditions. Specific Embodiments

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention belong. If the definitions stated in this part are contrary to or inconsistent with the definitions stated in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this part shall prevail over the definitions incorporated herein by reference.

[0028] Unless otherwise specified, the methods used in the following examples are all conventional methods. The materials, reagents, and instruments used, unless otherwise specified, are all conventional materials, reagents, and instruments in this field, and those skilled in the art can obtain them through commercial channels.

[0029] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper limit preferred values and lower limit preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this application, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0030] The aluminum alloy powder provided by the present invention is composed of Si, Mg, Y, Mo, Ti, Fe, and Al, and the preparation method includes:

[0031] Select high-purity aluminum ingots and raw materials in the form of metals or alloys of other metal elements. According to the ratio, put them into a furnace and melt them under a protective atmosphere. Control the melting temperature at 750 - 820 °C and the melting time at 1 - 2 h to ensure that all alloy elements are completely melted and a uniform alloy liquid is formed.

[0032] Inject the molten alloy liquid through a high-pressure nitrogen or argon gas stream. The flow rate of the high-pressure gas stream is 60 - 100 L / min, and the pressure of the high-pressure gas stream is 4 - 5 MPa. Rapid cooling at 2000 - 3000 °C / s forms powder;

[0033] Remove the surface oxide of the powder by hydrogen reduction, and then anneal the powder at 180 - 250 °C for 2 - 3 h and age it at 350 - 400 °C for 6 - 8 h.

[0034] The technical solutions of the present invention are further described below through different examples and comparative examples respectively.

[0035] Example 1

[0036] This example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 8.0 wt%, Mg: 4.5 wt%, Y: 1.5 wt%, Mo: 2.0 wt%, Ti: 2.0 wt%, Fe: 1.0%, and the balance is Al.

[0037] The preparation conditions are as follows:

[0038] Melting conditions: temperature 770 °C, melting time 1.5 h, using a nitrogen protective atmosphere to ensure complete melting of alloy elements.

[0039] Gas flow control: The high-pressure gas stream uses nitrogen, with a flow rate of 80 L / min, a gas pressure of 4.5 MPa, and a cooling rate of 2500 °C / s.

[0040] Post-treatment: Remove oxides by hydrogen reduction, anneal at 180 °C for 2 h, and age at 350 °C for 6 h.

[0041] The particle size distribution of the prepared powder is as follows:

[0042] Ultra-fine powder (<10 μm): 12 wt%

[0043] Fine powder (10 - 50 μm): 45 wt%

[0044] Medium powder (50 - 100 μm): 30 wt%

[0045] Coarse powder (100 - 150 μm): 13 wt%.

[0046] Example 2

[0047] This embodiment provides a method for preparing aluminum alloy powder. The composition ratio of the aluminum alloy powder is as follows: Si: 9.0 wt%, Mg: 5.0 wt%, Y: 2.0 wt%, Mo: 2.5 wt%, Ti: 2.5 wt%, Fe: 1.0%, and the balance is Al.

[0048] The preparation conditions are as follows:

[0049] Melting conditions: temperature 760 °C, melting time 1.5 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0050] Gas flow control: The high-pressure gas uses argon, with a flow rate of 90 L / min, a gas pressure of 4.8 MPa, and a cooling rate of 2700 °C / s.

[0051] Post-treatment: Hydrogen reduction to remove oxides, annealing at 200 °C for 2 h, and aging treatment at 375 °C for 7 h.

[0052] The particle size distribution of the prepared powder is as follows:

[0053] Ultra-fine powder (<10 μm): 14 wt%

[0054] Fine powder (10 - 50 μm): 42 wt%

[0055] Medium powder (50 - 100 μm): 28 wt%

[0056] Coarse powder (100 - 150 μm): 16 wt%.

[0057] Example 3

[0058] This embodiment provides a method for preparing aluminum alloy powder. The composition ratio of the aluminum alloy powder is as follows: Si: 7.5 wt%, Mg: 4.0 wt%, Y: 1.0 wt%, Mo: 2.0 wt%, Ti: 2.0 wt%, Fe: 1.2%, and the balance is Al.

[0059] The preparation conditions are as follows:

[0060] Melting conditions: temperature 750 °C, melting time 2 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0061] Gas flow control: The high-pressure gas uses argon, with a flow rate of 75 L / min, a gas pressure of 4.2 MPa, and a cooling rate of 2800 °C / s.

[0062] Post-treatment: Hydrogen reduction to remove oxides, annealing at 200 °C for 2 h, and aging treatment at 360 °C for 6 h.

[0063] The particle size distribution of the prepared powder is as follows:

[0064] Ultra-fine powder (<10 μm): 10 wt%

[0065] Fine powder (10 - 50 μm): 47 wt%

[0066] Medium powder (50 - 100 μm): 30 wt%

[0067] Coarse powder (100 - 150 μm): 13 wt%.

[0068] Example 4

[0069] This example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 8.5 wt%, Mg: 4.2 wt%, Y: 1.3 wt%, Mo: 2.0 wt%, Ti: 2.2 wt%, Fe: 1.0%, and the balance is Al.

[0070] The preparation conditions are as follows:

[0071] Melting conditions: temperature 820 °C, melting time 1 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0072] Gas flow control: high-pressure gas uses argon, flow rate 85 L / min, gas pressure 4.6 MPa, cooling rate 2600 °C / s.

[0073] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 3 h, aging treatment at 375 °C for 8 h.

[0074] The particle size distribution of the prepared powder is as follows:

[0075] Ultra-fine powder (<10 μm): 13 wt%

[0076] Fine powder (10 - 50 μm): 43 wt%

[0077] Medium powder (50 - 100 μm): 29 wt%

[0078] Coarse powder (100 - 150 μm): 15 wt%.

[0079] Comparative Example 1

[0080] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 8.0 wt%, Mg: 4.5 wt%, Y: 0.5 wt%, Mo: 1.5 wt%, Ti: 2.0 wt%, Fe: 1.0%, and the balance is Al.

[0081] The preparation conditions are as follows:

[0082] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protective atmosphere to ensure complete melting of alloying elements.

[0083] Gas flow control: high-pressure gas is argon, flow rate 80 L / min, gas pressure 4.5 MPa, cooling rate 2500 °C / s.

[0084] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 2 h, aging treatment at 350 °C for 6 h.

[0085] The particle size distribution of the prepared powder is as follows:

[0086] Ultra-fine powder (<10 μm): 8 wt%

[0087] Fine powder (10 - 50 μm): 47 wt%

[0088] Medium powder (50 - 100 μm): 32 wt%

[0089] Coarse powder (100 - 150 μm): 13 wt%.

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 10.0 wt%, Mg: 6 wt%, Y: 0.5 wt%, Mo: 1.0 wt%, Ti: 1.0 wt%, Fe: 1.0%, and the balance is Al.

[0092] The preparation conditions are as follows:

[0093] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protective atmosphere to ensure complete melting of alloying elements.

[0094] Gas flow control: high-pressure gas is argon, flow rate 80 L / min, gas pressure 4.5 MPa, cooling rate 2500 °C / s.

[0095] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 2 h, aging treatment at 350 °C for 6 h.

[0096] The particle size distribution of the prepared powder is as follows:

[0097] Ultra-fine powder (<10 μm): 9 wt%

[0098] Fine powder (10 - 50 μm): 44 wt%

[0099] Medium powder (50 - 100 μm): 30 wt%

[0100] Coarse powder (100 - 150 μm): 17 wt%.

[0101] Comparative Example 3

[0102] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 5.0 wt%, Mg: 1.5 wt%, Y: 0.3 wt%, Mo: 0.5 wt%, Ti: 1.0 wt%, Fe: 1.5%, and the balance is Al.

[0103] The preparation conditions are as follows:

[0104] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0105] Gas flow control: high-pressure gas uses argon, flow rate 70 L / min, gas pressure 4.0 MPa, cooling rate 2100 °C / s.

[0106] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 2 h, aging treatment at 350 °C for 6 h.

[0107] The particle size distribution of the prepared powder is as follows:

[0108] Ultra-fine powder (< 10 μm): 7 wt%

[0109] Fine powder (10 - 50 μm): 45 wt%

[0110] Medium powder (50 - 100 μm): 33 wt%

[0111] Coarse powder (100 - 150 μm): 15 wt%.

[0112] Comparative Example 4

[0113] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 9.0 wt%, Mg: 5 wt%, Y: 0.5 wt%, Mo: 1.5 wt%, Ti: 1.0 wt%, Fe: 1.5%, and the balance is Al.

[0114] The preparation conditions are as follows:

[0115] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0116] Gas flow control: high-pressure gas uses argon, flow rate 80 L / min, gas pressure 4.8 MPa, cooling rate 2400 °C / s.

[0117] Post-treatment: Remove oxides by hydrogen reduction, anneal at 180 °C for 2 h, and perform aging treatment at 350 °C for 6 h.

[0118] The particle size distribution of the prepared powder is as follows:

[0119] Ultra-fine powder (< 10 μm): 10 wt%

[0120] Fine powder (10 - 50 μm): 42 wt%

[0121] Medium powder (50 - 100 μm): 30 wt%

[0122] Coarse powder (100 - 150 μm): 18 wt%.

[0123] Comparative Example 5

[0124] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 12.0 wt%, Mg: 0.5 wt%, Y: 0.2 wt%, Mo: 0.5 wt%, Ti: 1.5 wt%, Fe: 1.0%, and the balance is Al.

[0125] The preparation conditions are as follows:

[0126] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protection atmosphere to ensure complete melting of alloy elements.

[0127] Gas flow control: high-pressure gas uses argon, flow rate 70 L / min, gas pressure 4.0 MPa, cooling rate 2200 °C / s.

[0128] Post-treatment: Remove oxides by hydrogen reduction, anneal at 180 °C for 2 h, and perform aging treatment at 350 °C for 6 h.

[0129] The particle size distribution of the prepared powder is as follows:

[0130] Ultra-fine powder (< 10 μm): 6 wt%

[0131] Fine powder (10 - 50 μm): 46 wt%

[0132] Medium powder (50 - 100 μm): 34 wt%

[0133] Coarse powder (100 - 150 μm): 14 wt%.

[0134] Comparative Example 6

[0135] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 7.0 wt%, Mg: 3 wt%, Ti: 1.0 wt%, Fe: 1.0%, and the balance is Al.

[0136] The preparation conditions are as follows:

[0137] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protective atmosphere to ensure complete melting of alloy elements.

[0138] Gas flow control: high-pressure gas is argon, flow rate 70 L / min, gas pressure 4.0 MPa, cooling rate 2100 °C / s.

[0139] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 2 h, aging treatment at 350 °C for 6 h.

[0140] The particle size distribution of the prepared powder is as follows:

[0141] Ultra-fine powder (<10 μm): 8 wt%

[0142] Fine powder (10 - 50 μm): 46 wt%

[0143] Medium powder (50 - 100 μm): 31 wt%

[0144] Coarse powder (100 - 150 μm): 15 wt%.

[0145] Comparative Example 7

[0146] This comparative example provides a method for preparing aluminum alloy powder. Among them, the composition ratio of the aluminum alloy powder is as follows: Si: 6.5 wt%, Mg: 7.0 wt%, Mo: 0.5 wt%, Ti: 2.5 wt%, Fe: 1.2%, and the balance is Al.

[0147] The preparation conditions are as follows:

[0148] Melting conditions: temperature 770 °C, melting time 1.5 h, using an argon protective atmosphere to ensure complete melting of alloy elements.

[0149] Gas flow control: high-pressure gas is argon, flow rate 85 L / min, gas pressure 4.5 MPa, cooling rate 2300 °C / s.

[0150] Post-treatment: hydrogen reduction to remove oxides, annealing at 180 °C for 2 h, aging treatment at 350 °C for 6 h.

[0151] The particle size distribution of the prepared powder is as follows:

[0152] Ultra-fine powder (<10 μm): 7 wt%

[0153] Fine powder (10 - 50 μm): 44 wt%

[0154] Medium powder (50 - 100μm): 32wt%

[0155] Coarse powder (100 - 150μm): 17wt%.

[0156] The aluminum alloy powders prepared in the above different examples and comparative examples were respectively subjected to laser melting 3D printing, and the printing accuracy was evaluated, and the results shown in the following table were obtained:

[0157]

[0158] Secondly, the samples obtained by the above 3D printing were placed in a high-temperature furnace, a constant stress was applied, and high-temperature creep tests were carried out. The test temperatures were set at 300, 400, and 500 °C respectively. The deformation rates of the materials at different temperatures and loads were recorded, and the creep rates were calculated. The results shown in the following table were obtained:

[0159]

[0160] The samples obtained by the above 3D printing were subjected to thermal cycling in the range of 200 - 600 °C, the number of cycles was 20 times, each cycle included a high-temperature stage and a low-temperature stage, and each stage was maintained for 30 min. The fatigue fracture surface was observed by scanning electron microscopy, and the crack growth rate was calculated. The results shown in the following table were obtained:

[0161]

[0162] Standard tensile tests were carried out on the samples obtained by the above 3D printing, the tensile strength, yield strength, and elongation were measured, and the hardness value was measured using a Vickers hardness tester. The results shown in the following table were obtained:

[0163]

[0164]

[0165] It can be seen from the above results that compared with the comparative example, the aluminum alloy powder of the example has better printing accuracy and lower surface roughness. The higher cooling rate and appropriate gas flow control conditions contribute to the uniformity of the powder, improve the stability during the laser melting process, and reduce defects.

[0166] The powders of the comparative example generally showed poor accuracy during printing and had higher surface roughness. In particular, the samples containing higher Si or lower Mg / Y ratios showed more printing defects.

[0167] The aluminum alloy powder of the example showed a lower creep rate at high temperatures, indicating its stronger stability at high temperatures and suitability for high-temperature applications.

[0168] The samples of the comparative examples had a high creep rate due to compositional deviations, especially the unreasonable contents of Si and Mg, indicating poor performance of these materials under high-temperature conditions.

[0169] In the thermal cycle test, the samples of the examples showed a low crack growth rate and had good heat-resistant fatigue performance.

[0170] The samples in the comparative examples had a high crack growth rate due to compositional imbalance and unsatisfactory particle size distribution.

[0171] The aluminum alloy powders of the examples showed high tensile strength, yield strength and elongation in the tensile test, and had moderate hardness values, indicating good comprehensive mechanical properties.

[0172] The samples of the comparative examples generally showed low mechanical properties. In particular, low Si content and inappropriate Mg / Y ratio may affect their strength and elongation.

[0173] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aluminum alloy powder that can be used for additive manufacturing, characterized in that, It comprises components with the following mass fractions: Si: 7.0 - 9.0 wt%, Mg: 3.5 - 5.5 wt%, Y: 1.0 - 2.0 wt%, Mo: 1.5 - 2.5 wt%, Ti: 1.5 - 2.5 wt%, Fe: 0.5 - 1.5%, and the balance is Al.

2. The aluminum alloy powder for additive manufacturing according to claim 1, characterized in that, It comprises components with the following mass fractions: Si: 8.0 wt%, Mg: 4.5 wt%, Y: 1.5 wt%, Mo: 2.0 wt%, Ti: 2.0 wt%, Fe: 1.0%, and the balance is Al.

3. The aluminum alloy powder for additive manufacturing according to claim 1, wherein The aluminum alloy powder includes ultra-fine powder, fine powder, medium powder and coarse powder, wherein the particle size d1 of the ultra-fine powder is < 10 μm, the particle size d2 of the fine powder is 10 ≤ d2 < 50 μm, the particle size d3 of the medium powder is 50 ≤ d3 < 100 μm, and the particle size d4 of the coarse powder is 100 ≤ d4 < 150 μm.

4. The aluminum alloy powder for additive manufacturing according to claim 3, characterized in that, Among the aluminum alloy powder, the proportion of the ultra-fine powder is 10 - 15 wt%, the proportion of the fine powder is 40 - 50 wt%, the proportion of the medium powder is 25 - 30 wt%, and the proportion of the coarse powder is 10 - 15 wt%.

5. A method for preparing an aluminum alloy powder for additive manufacturing according to any one of claims 1-4, characterized in that, It includes the following steps: Step 1: Select high-purity aluminum ingots and raw materials in the form of metals or alloys of other metal elements. According to the ratio, put them into a furnace and melt them under a protective atmosphere. Control the melting temperature at 750 - 820 °C and the melting time at 1 - 2 h to ensure that all alloy elements are completely melted and form a uniform alloy liquid. Step 2: Spray the molten alloy liquid through a high-pressure gas stream and rapidly cool it to form powder. Step 3: Remove the surface oxide of the powder by hydrogen reduction, then heat the powder to 180 - 250 °C for annealing treatment for 2 - 3 h, and heat it to 350 - 400 °C for aging treatment for 6 - 8 h.

6. The preparation method according to claim 5, characterized in that, The high-pressure gas stream uses nitrogen or argon.

7. The preparation method according to claim 5, wherein The flow rate of the high-pressure gas stream is 60 - 100 L / min.

8. The preparation method according to claim 5, characterized in that, The pressure of the high-pressure gas stream is 4 - 5 MPa.

9. The preparation method according to claim 5, characterized in that The cooling rate is 2000 - 3000 °C / s.

10. Application of the aluminum alloy powder for additive manufacturing according to any one of claims 1 - 4 in the fields of 3D printing, thermal spraying, cold spraying, powder metallurgy, and powder forging.

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