Aluminum alloy powder capable of being used for additive manufacturing and preparation method and application of aluminum alloy powder

Abstract

The invention relates to the technical field of additive manufacturing, and particularly provides aluminum alloy powder capable of being used for additive manufacturing and a preparation method and application of the aluminum alloy powder. The problems that an existing aluminum alloy is prone to creep deformation, thermal fatigue, hot cracks and the like in a high-temperature environment are solved. The aluminum alloy powder is composed of the following elements of, by mass, 7.0%-9.0% of Si, 3.5%-5.5% of Mg, 1.0%-2.0% of Y, 1.5%-2.5% of Mo, 1.5%-2.5% of Ti, 0.5%-1.5% of Fe and the balance Al. And by adding Y and Mo elements, a stable strengthening phase is formed, and the high-temperature creep resistance and thermal fatigue resistance of the alloy are improved. And by adding the Ti element, grains are further refined, and the mechanical property of the material is enhanced.

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 existing technology 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 its high temperature fatigue performance by optimizing the alloy composition, the existing technology still has the following shortcomings: 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 have improved the performance of aluminum alloys to a certain extent, the strengthening effect is limited under high temperature service, especially in extreme temperatures and long-term high temperature environments, it is still difficult to meet the long-term stability requirements under high temperature. 2. Most of the solutions in the existing technology only solve one aspect of the problem, such as improving the high temperature strength or fatigue resistance of aluminum alloys, and lack comprehensive optimization of multiple high temperature properties such as creep, thermal cracking, fatigue, etc. This makes the reliability and stability of additively manufactured aluminum alloy materials in actual high temperature environments poor. 3. Although some technologies adopt the strategy of adding multiple alloy elements, the alloy elements are often not completely evenly distributed during the powder preparation process, especially during the atomization process. The inhomogeneity of composition causes the aluminum alloy to be unable to obtain the desired mechanical properties during the 3D printing process, affecting its stability in high temperature environments.

[0006] How to solve problems such as high-temperature creep of aluminum alloys encountered in additive manufacturing has become a technical problem that needs 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 the problems such as high-temperature creep encountered by aluminum alloy powder 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 that can be used for additive manufacturing, which includes the following components in mass fraction: Si: 7.0-9.0wt%, Mg: 3.5-5.5wt%, Y: 1.0-2.0wt%, Mo: 1.5-2.5wt%, Ti: 1.5-2.5wt%, Fe: 0.5-1.5%, and the balance is Al.

[0009] In additive manufacturing, due to the rapid cooling of each layer, aluminum alloy prints are prone to uneven temperature gradients, which leads to the accumulation of thermal stress, which in turn increases the risk of creep and thermal cracking. Traditional aluminum alloys will creep significantly when serving at high temperatures, especially in environments above 400°C, affecting the strength and stability of the structure. The above scheme adopts a multi-element alloy design, using multiple strengthening designs of elements such as Si, Mg, Y, Mo, Ti, and Fe, which have good mechanical properties and high temperature creep resistance at high temperatures.

[0010] Specifically, the creep resistance of aluminum alloys is improved by adding yttrium (Y) and molybdenum (Mo) elements. Yttrium can promote the stability of precipitation phases in aluminum alloys and form fine Al3Y strengthening phases. These fine and stable precipitation phases can effectively hinder grain sliding, thereby enhancing the creep resistance of aluminum alloys at high temperatures. Molybdenum can increase the high-temperature strength of aluminum alloys, improve the solid solution strengthening effect of aluminum alloys, and improve the creep resistance at high temperatures. The combination of multiple alloying elements enhances the comprehensive properties of aluminum alloys, rather than the application of a single strengthening mechanism. Through the combination of these elements, the creep ability of aluminum alloys 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 alloys. In additive manufacturing, the use of these strengthening phases can effectively prevent the creep of aluminum alloys at high temperatures, especially when subjected to long-term loads.

[0011] Molybdenum, as an alloying element, dissolves in the aluminum matrix, causing lattice distortion, thereby increasing the strength of the alloy. 12 After the strengthening phase, it plays a role in hindering dislocation movement in the matrix, further improving the high temperature strength and creep resistance of the alloy.

[0012] By precisely controlling the content of each element, possible adverse interactions between elements are avoided. For example, too high Fe content may form brittle Al6Fe phase, affecting the ductility of the material. The optimization of element content ensures that the alloy precipitates a stable strengthening phase at high temperature without forming harmful intermetallic compounds.

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

[0014] In some embodiments, the aluminum alloy powder includes ultrafine powder, fine powder, medium powder and coarse powder, wherein the ultrafine powder has a particle size of less than 10 μm, the fine powder has a particle size of 10-50 μm, the medium powder has a particle size of 50-100 μm, and the coarse powder has a particle size of 100-150 μm.

[0015] In some embodiments, in the aluminum alloy powder, the ultrafine powder accounts for 10-15wt%, the fine powder accounts for 40-50wt%, the medium powder accounts for 25-30wt%, and the coarse powder accounts for 10-15wt%.

[0016] This refined and layered powder design helps to reduce stress concentration inside the material during rapid cooling and reduce the probability of thermal cracking. Ultrafine powder (<10μm) and microfine powder (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 improve its fatigue resistance. These elements enhance the material's resistance to fatigue crack propagation by forming a stable precipitate phase. Under long-term high-temperature cycling, 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 cracking, especially the addition of yttrium can enhance the toughness of the alloy at high temperatures and inhibit the formation of cracks. The titanium element helps to improve the thermal fatigue performance of aluminum alloys and enhances the resistance to thermal cracking by improving the grain boundary structure of the metal.

[0017] The second aspect of the present invention is to provide 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 metal or alloy of other metal elements, put them into a furnace and melt them under a protective atmosphere according to the proportion, control the melting temperature to 750-820℃, and the melting time to 1-2h to ensure that all alloy elements are completely melted and form a uniform alloy liquid;

[0019] Step 2: The molten alloy liquid is sprayed by high-pressure airflow and rapidly cooled to form powder;

[0020] Step 3: Remove oxides on the powder surface by hydrogen reduction, then heat the powder to 180-250°C for annealing for 2-3 hours, and heat to 350-400°C for aging for 6-8 hours.

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

[0022] By adjusting the air flow parameters and controlling the degree of fragmentation of the molten metal flow, the desired distribution of powder particle size can be obtained. High cooling rate helps to form fine and uniform powder particles and prevent segregation of alloy elements.

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

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses multi-element strengthening, including yttrium, molybdenum, titanium, etc., as well as powder particle size control and powder composition uniformity optimization, to carry out comprehensive design, effectively solving problems such as high-temperature creep, thermal cracking, fatigue, etc. This multi-dimensional optimization measure can systematically improve the high-temperature performance of aluminum alloys in the additive manufacturing process, especially its stability and reliability under extreme temperature conditions. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0028] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0029] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "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 herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges 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 metal or alloy of other metal elements, put them into the furnace and melt them under a protective atmosphere according to the proportion, control the melting temperature to 750-820℃, and the melting time to 1-2h to ensure that all alloy elements are completely melted and form a uniform alloy liquid.

[0032] The molten alloy liquid is sprayed with a high-pressure nitrogen or argon gas flow, the flow rate of the high-pressure gas flow is 60-100L / min, the pressure of the high-pressure gas flow is 4-5MPa, and it is quickly cooled at 2000-3000℃ / s to form powder;

[0033] The oxide on the powder surface is removed by hydrogen reduction, and then the powder is heated to 180-250°C for annealing for 2-3 hours and heated to 350-400°C for aging for 6-8 hours.

[0034] The technical solution of the present invention is further illustrated below through different embodiments and comparative examples.

[0035] Example 1

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

[0037] The preparation conditions are as follows:

[0038] Melting conditions: temperature 770℃, melting time 1.5h, using nitrogen protective atmosphere to ensure that the alloy elements are completely melted.

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

[0040] Post-treatment: hydrogen reduction to remove oxides, heating to 180℃ annealing for 2h, 350℃ aging treatment for 6h.

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

[0042] Ultrafine powder (<10μm): 12wt%

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

[0048] The preparation conditions are as follows:

[0049] Melting conditions: temperature 760°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

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

[0051] Post-treatment: hydrogen reduction to remove oxides, heating to 200℃ annealing for 2h, and 375℃ aging treatment for 7h.

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

[0053] Ultrafine powder (<10μm): 14wt%

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

[0059] The preparation conditions are as follows:

[0060] Melting conditions: temperature 750°C, melting time 2h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

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

[0062] Post-treatment: hydrogen reduction to remove oxides, heating to 200℃ annealing for 2h, and 360℃ aging treatment for 6h.

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

[0064] Ultrafine powder (<10μm): 10wt%

[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] The present embodiment provides a method for preparing aluminum alloy powder, wherein the composition of the aluminum alloy powder is as follows: Si: 8.5wt%, Mg: 4.2wt%, Y: 1.3wt%, Mo: 2.0wt%, Ti: 2.2wt%, Fe: 1.0%, and the remainder is Al.

[0070] The preparation conditions are as follows:

[0071] Melting conditions: temperature 820℃, melting time 1h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0072] Air flow control: The high-pressure air flow uses argon, with a flow rate of 85L / min, a gas pressure of 4.6MPa, and a cooling rate of 2600℃ / s.

[0073] Post-treatment: hydrogen reduction to remove oxides, heating to 180℃ annealing for 3h, and 375℃ aging treatment for 8h.

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

[0075] Ultrafine powder (<10μm): 13wt%

[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 an aluminum alloy powder, wherein the composition of the aluminum alloy powder is as follows: Si: 8.0wt%, Mg: 4.5wt%, Y: 0.5wt%, Mo: 1.5wt%, Ti: 2.0wt%, Fe: 1.0%, and the balance is Al.

[0081] The preparation conditions are as follows:

[0082] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0083] Airflow control: The high-pressure airflow uses argon, with a flow rate of 80L / min, a gas pressure of 4.5MPa, and a cooling rate of 2500℃ / s.

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

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

[0086] Ultrafine powder (<10μm): 8wt%

[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, wherein the composition of the aluminum alloy powder is as follows: Si: 10.0wt%, Mg: 6wt%, Y: 0.5wt%, Mo: 1.0wt%, Ti: 1.0wt%, Fe: 1.0%, and the balance is Al.

[0092] The preparation conditions are as follows:

[0093] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0094] Airflow control: The high-pressure airflow uses argon, with a flow rate of 80L / min, a gas pressure of 4.5MPa, and a cooling rate of 2500℃ / s.

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

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

[0097] Ultrafine powder (<10μm): 9wt%

[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, wherein the composition of the aluminum alloy powder is as follows: Si: 5.0wt%, Mg: 1.5wt%, Y: 0.3wt%, Mo: 0.5wt%, Ti: 1.0wt%, Fe: 1.5%, and the balance is Al.

[0103] The preparation conditions are as follows:

[0104] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0105] Airflow control: The high-pressure airflow uses argon, with a flow rate of 70L / min, a gas pressure of 4.0MPa, and a cooling rate of 2100℃ / s.

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

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

[0108] Ultrafine powder (<10μm): 7wt%

[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, wherein the composition of the aluminum alloy powder is as follows: Si: 9.0wt%, Mg: 5wt%, Y: 0.5wt%, Mo: 1.5wt%, Ti: 1.0wt%, Fe: 1.5%, and the balance is Al.

[0114] The preparation conditions are as follows:

[0115] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0116] Air flow control: The high-pressure air flow uses argon, with a flow rate of 80L / min, a gas pressure of 4.8MPa, and a cooling rate of 2400℃ / s.

[0117] Post-treatment: hydrogen reduction to remove oxides, heating to 180℃ annealing for 2h, 350℃ aging treatment for 6h.

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

[0119] Ultrafine powder (<10μm): 10wt%

[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 an aluminum alloy powder, wherein the composition of the aluminum alloy powder is as follows: Si: 12.0wt%, Mg: 0.5wt%, Y: 0.2wt%, Mo: 0.5wt%, Ti: 1.5wt%, Fe: 1.0%, and the balance is Al.

[0125] The preparation conditions are as follows:

[0126] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0127] Air flow control: The high-pressure air flow uses argon, with a flow rate of 70L / min, a gas pressure of 4.0MPa, and a cooling rate of 2200℃ / s.

[0128] Post-treatment: hydrogen reduction to remove oxides, heating to 180℃ annealing for 2h, 350℃ aging treatment for 6h.

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

[0130] Ultrafine powder (<10μm): 6wt%

[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, wherein the composition of the aluminum alloy powder is as follows: Si: 7.0wt%, Mg: 3wt%, Ti: 1.0wt%, Fe: 1.0%, and the balance is Al.

[0136] The preparation conditions are as follows:

[0137] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0138] Airflow control: The high-pressure airflow uses argon, with a flow rate of 70L / min, a gas pressure of 4.0MPa, and a cooling rate of 2100℃ / s.

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

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

[0141] Ultrafine powder (<10μm): 8wt%

[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, wherein the composition of the aluminum alloy powder is as follows: Si: 6.5wt%, Mg: 7.0wt%, Mo: 0.5wt%, Ti: 2.5wt%, Fe: 1.2%, and the balance is Al.

[0147] The preparation conditions are as follows:

[0148] Melting conditions: temperature 770°C, melting time 1.5h, using argon protective atmosphere to ensure that the alloy elements are completely melted.

[0149] Air flow control: The high-pressure air flow uses argon, with a flow rate of 85L / min, a gas pressure of 4.5MPa, and a cooling rate of 2300℃ / s.

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

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

[0152] Ultrafine powder (<10μm): 7wt%

[0153] Fine powder (10-50 μm): 44 wt%

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

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

[0156] The aluminum alloy powders prepared in the above different embodiments 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 3D printing were placed in a high-temperature furnace, constant stress was applied, and high-temperature creep tests were performed. The test temperatures were set to 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 are shown in the following table:

[0159]

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

[0161]

[0162] The samples obtained by 3D printing were subjected to standard tensile tests to measure tensile strength, yield strength and elongation, and the hardness value was measured using a Vickers hardness tester, and the results were shown in the following table:

[0163]

[0164]

[0165] The above results show that the aluminum alloy powder of the embodiment has better printing accuracy and lower surface roughness than the comparative example. A higher cooling rate and appropriate airflow 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 examples generally exhibited poor precision and high surface roughness during printing, especially the samples containing higher Si or lower Mg / Y ratios, which exhibited more printing defects.

[0167] The aluminum alloy powder of the embodiment exhibits a lower creep rate at high temperature, indicating that it has strong stability at high temperature and is suitable for high temperature applications.

[0168] The samples in the comparative examples have higher creep rates due to composition deviations, especially unreasonable contents of Si and Mg, indicating that these materials have poor performance under high temperature conditions.

[0169] In the thermal cycle test, the samples of the embodiment show a lower crack growth rate and have better thermal fatigue resistance.

[0170] The samples in the comparative example have a higher crack growth rate due to the unbalanced composition and unsatisfactory particle size distribution.

[0171] The aluminum alloy powder of the embodiment shows high tensile strength, yield strength and elongation in a tensile test, and has a moderate hardness value, showing good comprehensive mechanical properties.

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

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should 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: The invention comprises the following components in mass fractions: Si: 7.0-9.0wt%, Mg: 3.5-5.5wt%, Y: 1.0-2.0wt%, Mo: 1.5-2.5wt%, Ti: 1.5-2.5wt%, 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: The composition includes the following components in mass fractions: Si: 8.0wt%, Mg: 4.5wt%, Y: 1.5wt%, Mo: 2.0wt%, Ti: 2.0wt%, Fe: 1.0%, and the balance is Al.

3. The aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The aluminum alloy powder includes ultrafine powder, microfine powder, medium powder and coarse powder, wherein the ultrafine powder has a particle size of less than 10 μm, the microfine powder has a particle size of 10-50 μm, the medium powder has a particle size of 50-100 μm, and the coarse powder has a particle size of 100-150 μm.

4. The aluminum alloy powder for additive manufacturing according to claim 3, characterized in that: In the aluminum alloy powder, ultrafine powder accounts for 10-15wt%, fine powder accounts for 40-50wt%, medium powder accounts for 25-30wt%, and coarse powder accounts for 10-15wt%.

5. A method for preparing an aluminum alloy powder for additive manufacturing as claimed in any one of claims 1 to 4, characterized in that: The steps include: Step 1: Select high-purity aluminum ingots and raw materials in the form of metal or alloy of other metal elements, put them into a furnace and melt them under a protective atmosphere according to the proportion, control the melting temperature to 750-820℃, and the melting time to 1-2h to ensure that all alloy elements are completely melted and form a uniform alloy liquid; Step 2: The molten alloy liquid is sprayed by high-pressure airflow and rapidly cooled to form powder; Step 3: Remove oxides on the powder surface by hydrogen reduction, then heat the powder to 180-250°C for annealing for 2-3 hours, and heat to 350-400°C for aging for 6-8 hours.

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

7. The preparation method according to claim 5, characterized in that: The flow rate of high pressure air flow is 60-100L / min.

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

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

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

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