Aluminum alloy powder for additive manufacturing and manufacturing method thereof

Abstract

The invention relates to aluminum alloy powder for additive manufacturing and a manufacturing method of the aluminum alloy powder. The manufacturing method comprises the following steps that aluminum elementary substance and aluminum-based intermediate alloy containing magnesium and manganese elements are put into a smelting crucible according to the design proportion; the smelting crucible is vacuumized and then filled with inert gas, so that a negative pressure environment is formed; the temperature of the smelting crucible is increased to 700-750 DEG C, so that the aluminum elementary substance and the aluminum-based intermediate alloy are molten, and a first melt is obtained; the temperature of the first melt is increased to 800-850 DEG C, and a second melt is obtained; preparing the second melt into powder by adopting a gas atomization method; and the powder is screened, and the aluminum alloy powder with the particle size ranging from 15 micrometers to 53 micrometers is obtained. The aluminum alloy powder manufacturing method provided by the invention has the advantage of inhibiting the loss of elements easy to burn out.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing, and more specifically, to an aluminum alloy powder for additive manufacturing and a method for manufacturing the same. Background Art

[0002] In the laser additive manufacturing process, aluminum alloy powder is usually used as the raw material. This technology requires the powder to have good flowability and sphericity, and more importantly, it must have a precise and stable chemical composition to ensure the performance of the final formed part.

[0003] However, existing aluminum alloy powder manufacturing methods, such as gas atomization, present significant challenges. During the high-temperature smelting stage, key elements in the aluminum alloy, such as magnesium (Mg) and manganese (Mn), which are susceptible to burnout, experience significant volatilization losses due to their low boiling points, high vapor pressures, or susceptibility to oxidation.

[0004] This burnout causes the actual chemical composition of the powder to deviate from the design target, particularly insufficient levels of strengthening elements like Mg and Mn. The consequence is a decline in powder quality, ultimately affecting the mechanical properties (such as strength and hardness) and process stability of the AM part, and increasing production costs (due to the need for excessive element additions).

[0005] Therefore, it is urgent to develop a method for preparing aluminum alloy powder that can effectively inhibit the loss of elements that are easily burned, so as to obtain high-performance powder with precise and stable composition. Summary of the Invention

[0006] The present application provides aluminum alloy powder for additive manufacturing and a method for manufacturing the same, in order to solve the technical problem that magnesium (Mg) and manganese (Mn) are easily burned and volatilized during the preparation of aluminum alloy powder, resulting in serious volatilization losses and deviations of the chemical composition of the powder from the design value.

[0007] A method for producing aluminum alloy powder for laser additive manufacturing comprises the following steps: placing aluminum and an aluminum-based master alloy containing magnesium and manganese in a designed ratio into a melting crucible. The crucible is evacuated and then filled with an inert gas to create a negative pressure environment. The crucible is heated to 700-750°C to melt the aluminum and the aluminum-based master alloy to obtain a first melt. The first melt is heated to 800-850°C to obtain a second melt. The second melt is prepared into a powder using a gas atomization method. The powder is screened to obtain the aluminum alloy powder having a particle size range of 15-53 μm. The aluminum alloy powder comprises, by mass, the following components: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; and Zr, 0.4%-0.7%. The remainder is Al and unavoidable impurities.

[0008] In some possible implementations, the aluminum-based master alloy includes AlMn master alloy, AlMg master alloy, AlSc master alloy and AlZr master alloy.

[0009] In some possible implementations, the step of "raising the temperature of the melting crucible to 700-750° C." includes raising the temperature of the melting crucible to 700-750° C. at a heating rate of 10-20° C. / min. The step of "evacuating the melting crucible and then filling it with an inert gas to form a negative pressure environment" includes evacuating the melting crucible to below 0.1 Pa and then filling it with inert gas to a negative pressure of 99.5 kPa.

[0010] In some possible implementations, the step of "raising the temperature of the first melt to 800-850° C." further includes the step of electromagnetically stirring the first melt and keeping the temperature for 10-15 minutes.

[0011] In some possible embodiments, the step of "preparing the second melt into powder by a gas atomization method" includes the steps of: tilting the furnace body so that the second melt passes into the atomization chamber through the tundish crucible and the guide tube, and simultaneously spraying high-pressure gas for atomization and powdering.

[0012] The guide tube is made of boron nitride or zirconium oxide, and the diameter of the flow restriction opening of the guide tube is 3-6 mm. The spray disc in the atomization chamber is a ring-slit type tightly coupled atomizing spray disc, and the atomization pressure of the high-pressure gas is 1.5-4.0 MPa.

[0013] An aluminum alloy powder manufactured by the above-mentioned aluminum alloy powder manufacturing method includes the following components in weight percentage: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr, 0.4%-0.7%; the balance is Al and inevitable impurities.

[0014] In some possible embodiments, the composition includes the following weight percentages: Mn, 2.3%, Mg, 1.8%, Sc, 0.7%, Zr, 0.6%, and the balance is Al and unavoidable impurities.

[0015] In some possible embodiments, the composition includes the following weight percentages: Mn, 1.5%, Mg, 1.6%, Sc, 0.8%, Zr, 0.6%, and the balance is Al and unavoidable impurities.

[0016] In some possible embodiments, the composition includes the following weight percentages: Mn, 2.5%, Mg, 2.5%, Sc, 0.8%, Zr, 0.7%, and the balance is Al and unavoidable impurities.

[0017] In some possible embodiments, the composition includes the following weight percentages: Mn, 2.0%, Mg, 2.0%, Sc, 0.7%, Zr, 0.6%, and the balance is Al and unavoidable impurities.

[0018] In this application, master alloys with melting points close to pure aluminum (such as AlMn and AlMg) are used instead of pure metals as raw materials. Master alloys can reduce melting temperatures and shorten melting times. Pure metals such as Mn and Zr have melting points much higher than aluminum (660°C). While Mg has a low melting point, it also has a low boiling point and is volatile. Traditional methods for melting these high-melting-point metals require maintaining temperatures well above the melting point of aluminum (e.g., above 750°C) for extended periods. This creates intense volatilization conditions for low-boiling-point elements like Mg and Mn, leading to severe burnout. The selected master alloys (e.g., Al-50Mn, with a melting point of approximately 710-730°C) have melting points close to pure aluminum. Therefore, in a vacuum melting crucible, all raw materials (pure aluminum ingot and master alloys) can be melted rapidly and simultaneously by simply controlling the temperature slightly above the melting point of aluminum (e.g., 700-750°C). This reduces the high-temperature environment required to melt high-melting-point pure metals and shortens the total time the alloy melt remains in a high-temperature liquid state. Because the extent of elemental volatilization loss is strongly dependent on temperature and time (high temperatures and long periods of time exacerbate losses), this combination of "low-temperature melting" and "short-term operation" effectively suppresses the volatilization of Mg and Mn, which are easily lost during the melting stage, thereby maximizing the retention of the target composition and improving the chemical stability and precision of the powder. Furthermore, the inert gas environment further reduces oxidation losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a morphology diagram of the aluminum alloy powder prepared in Example 1.

[0021] Figure 2 This is the morphology of the aluminum alloy powder prepared in Comparative Example 3.

[0022] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be an element centered therein. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be an element centered therein. When an element is considered to be "set on" another element, it may be directly set on the other element or there may also be an element centered therein. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "or / and" as used herein includes any and all combinations of one or more of the relevant listed items.

[0026] Some embodiments of the present application are described in detail. In the absence of conflict, the following embodiments and features of the embodiments can be combined with each other.

[0027] The embodiments of the present application provide a method for manufacturing aluminum alloy powder for additive manufacturing to solve the problem in the prior art of severe loss of volatile elements such as magnesium (Mg) and manganese (Mn), resulting in unstable chemical composition of the aluminum alloy powder.

[0028] The aluminum alloy powder manufacturing method includes the following steps: S1: Aluminum and an aluminum-based master alloy containing magnesium and manganese elements are placed into a melting crucible according to a designed ratio. The melting crucible includes a corundum crucible or a graphite crucible.

[0029] In this embodiment, the aluminum element is a pure aluminum ingot with a purity of Al99.85% or more. The aluminum-based master alloys include AlMn master alloys, AlMg master alloys, AlSc master alloys, and AlZr master alloys.

[0030] The AlMn master alloy includes one of the grades AlMn10, AlMn15, AlMn20, AlMn25, AlMn30, and AlMn40. The AlMg master alloy includes one of the grades AlMg20, AlMg25, AlMg50, and AlMg60. The AlSc master alloy includes one of the grades AlSc2, AlSc5, and AlSc10. The AlZr master alloy includes one of the grades AlZr3, AlZr4, AlZr5, AlZr5A, AlZr6, AlZr10, and AlZr10A. The grades refer to the commercial concentration designations of the primary alloying elements in the master alloy, typically directly corresponding to the approximate mass percentage content of the elements. Preferably, the AlMn master alloy is AlMn10. The AlMg master alloy is AlMg20. The AlSc master alloy is AlSc2. The AlZr master alloy is AlZr5A.

[0031] Specifically, in this embodiment, each brand can be understood as follows: Table 1: Aluminum-based intermediate alloy grades and corresponding components and mass percentages S2: The crucible is evacuated and then filled with an inert gas to form a negative pressure environment.

[0032] In this embodiment, step S2 includes first placing a crucible containing a precisely proportioned mixture of aluminum and a master alloy into a melting apparatus with a vacuum chamber. A roughing pump is activated to rapidly reduce the chamber pressure to approximately 0.1 Pa, and then a molecular pump is used to further pump the pressure down to no more than 0.1 Pa to minimize the removal of air and moisture. In this ultra-high vacuum environment, the oxygen partial pressure and water vapor content within the chamber are reduced to extremely low levels, providing initial protection for the active elements in the melt.

[0033] After the vacuum reaches the set value, close the vacuum pump interface and slowly open the inert gas (argon or nitrogen) flow path. Using the precision pressure regulating valve, adjust the chamber pressure to a slightly negative pressure of approximately 99.5 kPa. During this process, the inert gas fills the entire melting crucible, not only maintaining a low-oxygen environment but also forming a protective atmosphere to prevent the backflow of external air. Repeating this brief vacuum-and-gas cycle further ensures that any remaining trace impurities are removed. Ultimately, a stable, slightly negative pressure inert atmosphere is achieved, meeting the process requirements for suppressing element volatilization during subsequent high-temperature melting.

[0034] S3: heating the melting crucible to 700-750° C. to melt the aluminum element and the aluminum-based master alloy to obtain a first melt.

[0035] In this embodiment, step S3 includes: melting in a medium frequency induction melting furnace, gradually increasing the temperature during the melting process at a heating rate of 10-20°C / min, and controlling the melting temperature between 700-750°C to ensure that the aluminum element and the aluminum-based master alloy are fully melted to form a first melt. Stirring with an electromagnetic stirrer at 700-750°C and maintaining the temperature for 10-15 minutes.

[0036] S4: heating the first melt to 800-850° C. to obtain a second melt.

[0037] Among them, after the composition of the first melt is homogenized, the temperature is raised to 800-850℃, mainly to "superheat" the first melt so that it obtains sufficient fluidity and suitable physical properties to adapt to the subsequent atomization powder making process. Specifically, high temperatures above 800℃ can significantly reduce the viscosity and surface tension of the aluminum alloy melt, which helps the droplets to quickly break at the spray plate and form finer and more uniform atomized particles; at the same time, moderate overheating can also cause the second melt to solidify early due to local insufficient temperature in the guide tube or spray plate, thereby reducing the risk of blockage and particle size fluctuations. In other words, the purpose of the temperature increase in step S4 is to provide a "high-energy state" second melt for gas atomization, ensure that the powder particle size is controllable, the morphology is regular, and the chemical composition is maintained to the greatest extent possible.

[0038] S5: preparing the second melt into powder by a gas atomization method.

[0039] In this embodiment, step S5 involves pouring a second melt at 800–850°C into a tundish crucible equipped with a silicon carbide or zirconium oxide ceramic filter (10 ppi) via a tilting melting crucible to filter and remove minor inclusions. The second melt then steadily flows into the atomization chamber via a boron nitride or zirconium oxide draft tube with a 4.0–4.5 mm flow restriction. At this point, a high-pressure inert gas (99.999% pure nitrogen or argon) at 2.0–3.0 MPa is simultaneously injected through an annular, tightly coupled atomizing nozzle.

[0040] High-speed airflow impacts and shears the melt, breaking it into atomized droplets with diameters ranging from 15–53 μm. During this process, the filter ensures melt purity, the flow tube maintains a stable flow rate, and the spray plate and air pressure jointly determine the strength of the atomizing shear force, thereby controlling the droplet generation rate and size distribution. Ultimately, at high temperature and high speed, a nearly spherical, uniformly distributed aluminum alloy powder is formed.

[0041] S6: Screening the powder to obtain the aluminum alloy powder with a particle size range of 15-53 μm.

[0042] In this embodiment, step S6 involves first feeding the coarse powder obtained through atomization into an airflow classifier under an inert gas shield. Utilizing the centrifugal interception principle of an adjustable rotor, the airflow separates the powder into coarse and fine fractions. Large particles that do not meet the required standards are discharged through the classifier outlet and returned to the furnace, while fine powder is transported along with the airflow to a collection system. During operation, the particle size cutoff can be precisely set by adjusting the classifier inlet air velocity and the classifying wheel speed. After multiple cycles of classification, an aluminum alloy powder with a particle size range of 15–53 μm is obtained. Using a laser particle size analyzer, the finished powder's particle size distribution measures D10: 15–25μm, D50: 30–40μm, and D90: 50–65μm. Under optimal operating conditions, the particle size distribution reaches D10: 17–23μm, D50: 30–40μm, and D90: 45–53μm, ensuring the powder has excellent flowability and spreadability while meeting the fineness and sphericity requirements for additive manufacturing. D10 is the value below which particles account for 10% of the total mass. D50 is the value below which particles account for 50% of the total mass. D90 is the value below which particles account for 90% of the total mass.

[0043] Compared with the existing technology, the manufacturing method provided by this application has the following advantages: (1) The preparation method of the present application uses an intermediate alloy with a melting point close to that of pure aluminum as a raw material, which reduces the smelting time and greatly reduces the loss of Mg and Mn, which are easily burned elements. The melting points of pure metals such as Mn and Zr are much higher than that of aluminum (660°C). Although Mg has a low melting point, it has a low boiling point and is easily volatile. In order to melt these high-melting-point metals, the traditional method must maintain a temperature much higher than the melting point of aluminum for a long time (such as above 750°C), which provides strong volatilization conditions for low-boiling-point elements such as Mg and Mn, resulting in serious burning. The melting point of the selected intermediate alloy (such as Al-50Mn with a melting point of about 710-730°C) is close to that of pure aluminum. Therefore, in the vacuum melting crucible, it is only necessary to control the temperature in a range slightly higher than the melting point of aluminum (such as 700-750°C) to make all raw materials (pure aluminum ingots and various intermediate alloys) melt quickly and synchronously. In this way, the high-temperature environment required for melting high-melting-point pure metals is avoided, and the total time that the alloy melt is in a high-temperature liquid state is shortened. Since the extent of element volatilization loss is strongly dependent on temperature and time (high temperature and long time exacerbate the loss), this combination of "low temperature melting" and "short time operation" effectively suppresses the volatilization of easily burned elements such as Mg and Mn during the melting stage, thereby retaining the target composition to the greatest extent and improving the chemical stability and accuracy of the powder.

[0044] (2) The preparation method of the present application uses electromagnetic stirring to promote the homogenization of alloy elements and reduce the composition segregation caused by the density difference of different elements.

[0045] (3) The preparation method of the present application optimizes the yield and quality of the finished powder of 15-53 μm by reasonably adjusting the powder control process parameters such as melt temperature, guide tube diameter, atomizing gas pressure, etc.

[0046] (4) The preparation method of the present application uses an inert gas protected air flow classifier for classification, which can reduce the oxidation of the powder and at the same time the particle size control of the aluminum alloy powder is more precise.

[0047] An aluminum alloy powder manufactured by the above-mentioned aluminum alloy powder manufacturing method includes the following components in weight percentage: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr, 0.4%-0.7%; the balance is Al and inevitable impurities.

[0048] Furthermore, the composition includes the following components in weight percentage: Mn, 2.3%, Mg, 1.8%, Sc, 0.7%, Zr, 0.6%, and the balance is Al and inevitable impurities.

[0049] Furthermore, the composition includes the following components in weight percentage: Mn, 1.5%, Mg, 1.6%, Sc, 0.8%, Zr, 0.6%, and the balance is Al and inevitable impurities.

[0050] Furthermore, the composition includes the following components in weight percentage: Mn, 2.5%, Mg, 2.5%, Sc, 0.8%, Zr, 0.7%, and the balance is Al and inevitable impurities.

[0051] Furthermore, the composition includes the following components in weight percentage: Mn, 2.0%, Mg, 2.0%, Sc, 0.7%, Zr, 0.6%, and the balance is Al and inevitable impurities.

[0052] Among them, the addition of Mn and Mg elements mainly plays the role of solid solution strengthening. By reasonably adjusting the content of Mn and Mg elements, the solid solution strengthening effect of Mn and Mg can be synergistic. It reduces the precipitation of large-particle brittle second phases such as Mg2Si and Al6Mn caused by excessive Mn and Mg content, and reduces the generation of pores and a large amount of spatter caused by excessive Mg content, which can cause printing defects. The addition of Sc and Zr elements preferentially precipitates nano-scale Al3Sc, Al3Zr particles or composite components during the solidification process, which serve as aluminum-based heterogeneous nucleation points to refine the grains. At the same time, during the aging heat treatment of the product, fine second-phase particles precipitate from the supersaturated solid solution, which has the effect of precipitation strengthening.

[0053] The present application is described in detail below in conjunction with representative embodiments to help understand the spirit of the present application, but does not limit the scope of the present application in any way.

[0054] Example 1 An aluminum alloy powder for laser additive manufacturing is composed of the following components in mass percentage: Mn 2.3%, Mg 1.8%, Sc 0.7%, Zr 0.6%, and the balance is Al and inevitable impurities. The specific preparation process is as follows: (1) weighing 99.85% pure aluminum ingots, AlMn10 master alloy, AlMg20 master alloy, AlSc2 master alloy, and AlZr5A master alloy into a vacuum melting crucible; (2) evacuating the powder making equipment to below 0.1Pa, and then filling in inert gas to a slightly negative pressure state of 99.5KPa, repeating the above vacuuming and filling for 3 times; (3) turning on the medium frequency induction melting power supply, and gradually increasing the melting power every 10 minutes to 15Kw / 10min, 30Kw / 10min, 50Kw / 10min, and 80Kw until it is completely melted. , readjust the power to 50Kw, and perform temperature control so that the melting temperature is controlled at 700-750℃; (4) When all the raw materials are melted to a molten state, turn on the electromagnetic stirrer and keep it warm for 12 minutes; (5) After the insulation is completed, adjust the power to 80Kw to heat the melt. When the melt temperature reaches 830℃ and the ladle temperature is 850℃, immediately tilt the furnace body for pouring. The diameter of the guide tube is 4mm, and 2.5Mpa argon is sprayed at the same time for atomization and powdering; (6) The atomized powder is classified by an inert gas protection airflow classifier to obtain the 15-53μm powder required for additive manufacturing.

[0055] Examples 2 to 4 The difference from Example 1 is that the aluminum alloy powders of Examples 2 to 4 have different component contents, expressed in mass percentage, as shown in Table 2. The preparation methods of the aluminum alloy powders of Examples 2 to 4 are the same as that of Example 1.

[0056] Table 2 Mass percentage of the components of the aluminum alloy powders of Examples 2 to 4 Comparative Examples 1-2 An aluminum alloy powder for laser additive manufacturing is prepared by the same method as in Example 1. The difference is that the components and contents by mass percentage of the aluminum alloy powder are as shown in Table 3.

[0057] Table 3 Mass percentage of the components of the aluminum alloy powders of Comparative Examples 1 and 2 Comparative Example 3 A method for manufacturing aluminum alloy powder for laser additive manufacturing, wherein the chemical composition is consistent with that of Example 1. The specific method is as follows: (1) weighing 99.85% pure aluminum ingot, AlMn10 master alloy, AlMg20 master alloy, AlSc2 master alloy, and AlZr5A master alloy into a vacuum melting crucible; (2) evacuating the powder making equipment to below 20 Pa, and then adding inert gas to a slightly negative pressure state of 99.5 KPa; (3) turning on the medium frequency induction melting power supply, and gradually increasing the melting power every 10 minutes, 15Kw / 10min, 30Kw / 10min, 50Kw / 10min, 80Kw / 10min, etc. After complete melting, the power is readjusted to 50Kw and the temperature is controlled so that the melting temperature is controlled at 800-850℃; (4) After the insulation is completed, the power is adjusted to 80Kw to heat the melt. When the melt temperature reaches 900℃ and the tundish temperature is 850℃, the furnace body is immediately tilted for pouring. The diameter of the guide tube is 5mm, and 5.0Mpa argon is sprayed at the same time for atomization and powdering; (5) The atomized powder is classified by an inert gas protection airflow classifier to obtain the 15-53μm powder required for additive manufacturing.

[0058] The preparation methods of Example 1 and Comparative Example 3 differ in the following: (1) In Example 1, the vacuum level is first evacuated to ≤0.1 Pa using a two-stage mechanical pump and molecular pump. Argon is then introduced to a slightly negative pressure of 99.5 kPa, and the "evacuation-venting" cycle is repeated three times to maximize the removal of oxygen and moisture. In Comparative Example 3, the chamber is only evacuated to 20 Pa and then vented once, without a deep vacuum or cyclic process. (2) In Example 1, the power is increased in stages (15 kW → 30 kW → 50 kW → 80 kW) until melting, then adjusted back to 50 kW for precise temperature control, maintaining a stable melting temperature of 700–750°C. In Comparative Example 3, the melting temperature is controlled within the 800–850°C range after the power is increased in stages, without a reduction stage. (3) In Example 1, an electromagnetic stirrer is activated within the 700–750°C holding range for 12 minutes to ensure uniform melt composition. Comparative Example 3 does not involve any stirring or dedicated holding and homogenization steps. (IV) After the insulation period in Example 1, the melt was heated to approximately 830°C (80kW), with the tundish crucible temperature at approximately 850°C, before atomization. In Comparative Example 3, the melt was heated to 900°C before atomization. (V) In Example 1, the draft tube had a diameter of 4.0–4.5 mm and was made of boron nitride or zirconium oxide; the annular gap-type, tightly coupled spray disc was used with an inert gas pressure of 2.0–3.0 MPa. In Comparative Example 3, the draft tube had a diameter of 5 mm and the spray gas pressure was 5.0 MPa. (VI) In Example 1, an airflow classifier was used under inert gas protection, and multiple cycles were performed to obtain a particle size concentrated in the 15–53 μm range. Comparative Example 3 also performed classification but did not emphasize multiple cycles, nor did it fine-tune the classification parameters.

[0059] In summary, Example 1 has undergone refined design and multiple cycle optimization in key links such as vacuum protection, melting temperature control, melt stirring, superheat temperature and spray parameters, and grading and screening, so as to systematically suppress the loss of volatile elements and improve the purity and morphology uniformity of the powder; while Comparative Example 3 simplifies many places or adopts more "radical" high-temperature and high-pressure parameters, which may sacrifice composition control and powder quality, resulting in its sphericity, composition stability and grading effect being inferior to Example 1.

[0060] The properties of the aluminum alloy powders prepared by the preparation methods in Examples 1 to 4 of the present application and the preparation methods in Comparative Examples 1 to 3 were tested, analyzed and evaluated.

[0061] (1) Aluminum alloy powder performance test: According to GB / T39251 “Method for Characterizing Properties of Metal Powders for Additive Manufacturing”, the properties of the 15-53 μm aluminum alloy powders prepared in the examples and comparative examples were compared, as shown in Table 4.

[0062] Table 4 Comparison of aluminum alloy powder performance between the embodiment and the comparative example In terms of component content, as shown in Table 4 for Examples 1-4 and Comparative Examples 1-2, the Examples (Mn 1.5-2.5%, Mg 1.6-2.5%, Sc 0.5-0.8%, Zr 0.4-0.7%) exhibit lower oxygen content (152 ppm vs. 180 ppm, a 15.6% decrease), smaller angle of repose (31.25° vs. 34.00°, an 8.1% decrease), lower hollow powder rate (0.975% vs. 1.25%, a 2% decrease), and slightly higher bulk density and sphericity compared to Comparative Examples 1-2. A high Mg content (Comparative Example 2, Mg 4.5%) leads to increased oxygen content, decreased sphericity, increased hollow powder content, and poor flowability, indicating that excessively high Mg content can amplify oxidation / volatilization and poor forming within this process window.

[0063] As for the manufacturing method, as shown in Table 4 for Examples 1-4 and Comparative Example 3, Example 1, through multiple deep vacuum pumping, temperature control at 700-750°C with stirring and homogenization, moderate overheating, and optimized atomization / classification, reduced the oxygen content from 280 ppm to 154 ppm (a 45% reduction), the hollow powder rate from 3.5% to 1.0% (a 71% reduction), the sphericity from 85% to 91% (a 6 percentage point increase), and the angle of repose from 42° to 32° (a 10° increase). The bulk density and tap density increased by 23% and 9%, respectively. Although the target particle size yield was 5 percentage points lower than that of Comparative Example 3, the overall powder quality was significantly improved.

[0064] (II) Comparative analysis of gold powder SEM morphology: The following is a comparison of the two SEM morphology images of Example 1 ( Figure 1 ) and comparative example three ( Figure 2 ) by comparing the morphology characteristics of the aluminum alloy powders obtained, it can be found that: 1. Sphericity and overall morphology Example 1 ( Figure 1 ): The powder particles are highly spherical, with almost no trace of droplets that are severely stretched and deformed. The outlines of most particles are smooth and complete, indicating that the shear force and surface tension during the atomization and solidification process are well balanced. Figure 2 ): Although round particles can be seen, there are obviously more irregular, flat "tear drop" shapes or agglomerates with uneven surface contours, indicating that some droplets have undergone early condensation or adhesion during the atomization or rapid solidification process.

[0065] 2. Surface quality and spatter Example 1: The particle surface is relatively clean, with only sporadic "satellites" (tiny attached satellite particles) or a very small number of protrusions visible, indicating that the tundish filter and draft tube solution effectively remove large inclusions, and the inert gas and high-temperature superheating allow the molten droplets to solidify smoothly. Comparative Example 3: The surface is covered with spatter clumps of varying sizes, and a large number of satellites are attached, seriously affecting powder flowability and powder spreading uniformity. This may be because the smaller draft aperture and moderate air pressure in Example 1 combine to produce more ideal shear force, resulting in a more uniform droplet size. In Comparative Example 3, while the excessive spray pressure produces a finer powder, it also tends to cause more spatter and satellite attachment.

[0066] 3. Size distribution and grading effect Example 1: Figure 1 The diameter of the visible particles is mostly concentrated in the range of 20-50μm (about 1-3 times the 50μm scale in the figure), and the size distribution of the edge particles is relatively concentrated, with no obvious large particles or agglomerates. Figure 2 Numerous large particle agglomerates exceeding 50 μm and multiple small particles < 15 μm can be seen in the sample, and the particle size distribution is wide, indicating that the efficiency of the grading and screening process is insufficient.

[0067] 4. Holes and internal defects Example 1: Figure 1 Very few open holes or hollow powders were observed, and the powder particles were solid; this is closely related to the vacuum-inert gas protection and precise temperature control, which can reduce the dissolution and precipitation of gas in the melt. Figure 2 There are obvious holes or depressions on the surface of the middle powder particles (hollow powder), indicating that during the melt injection and rapid solidification stages, the gas was trapped in the powder before it could escape.

[0068] In summary, the aluminum alloy powder prepared in Example 1 has regular morphology, high sphericity, smooth surface, narrow particle size distribution and no obvious hollow powder, which greatly improves the powder fluidity and subsequent laser powder spreading uniformity; while Comparative Example 3 has defects such as low sphericity, many spatters, wide particle size distribution, and high hollow powder rate, all of which are not conducive to high-quality laser additive manufacturing.

[0069] (3) Mechanical properties testing of printed parts: The following is a printing test and analysis evaluation of the aluminum alloy powders produced in Examples 1 to 4 of the present application and the aluminum alloy powders produced in Comparative Examples 1 to 3.

[0070] The aluminum alloy powders produced in Examples 1-4 and Comparative Examples 1-3 were printed on an HBDP400 selective laser melting device to test the performance of the printed parts. The device uses the following printing parameters: laser power of 300W, layer thickness of 40μm, scanning pitch of 0.1mm, and laser scanning speed of 1000mm / s.

[0071] After printing, the printed parts were heat treated to reduce residual stress and enhance precipitation strengthening. The heat treatment process was as follows: heating from room temperature to 325°C over 1 hour, holding at 325°C for 2 hours, and then removing from the heat and air cooling.

[0072] The printed parts were subjected to mechanical property testing. Room temperature tensile properties (strength and elongation) were tested according to GB / T228.1-2021, and fracture toughness was tested according to GB / T4161-2007. The results are shown in Table 5.

[0073] Table 5 Comparison of mechanical properties of printed parts of the embodiment and the comparative example Combining Table 4 and Table 5, we can see that under the condition of constant components, the analysis of Example 1 and Comparative Example 3 shows that the powder making method of the embodiment can significantly improve the plasticity and toughness of the printed parts. Specifically, the elongation is increased from 12% to 18.5% (an increase of 54%), and the fracture toughness is increased from 20.5 to 39 MPa·m 1 / 2 (Increased by 90%); tensile strength increased from 520 to 480 MPa (decreased by 7.7%). These results are consistent with the significant reduction in oxygen content, improved sphericity, and decreased hollow powder ratio shown in Table 4, indicating that the milling process of Example 1 of the present application can inhibit the burnout of key elements such as Mg, Mn, Sc, and Zr, reduce oxygen content and brittle inclusions, and improve element retention, ensuring microstructural strengthening and toughening, thereby improving crack growth resistance.

[0074] Combining Tables 4 and 5, it can be seen that under the same milling method, Examples 1 to 4 generally exhibit higher elongation and fracture toughness than Comparative Examples 1 and 2, and can achieve a balance under different strength targets: equivalent strength, improved toughness (Example 4 vs. Comparative Example 2): strength is approximately 520 MPa, elongation is increased by 25%, and fracture toughness is increased by 70%; high-strength solution (Example 3 vs. Comparative Example 2): strength is increased by 11.9% and elongation and fracture toughness are simultaneously improved; high-toughness solution (Example 2 vs. Comparative Example 2): fracture toughness is increased by 110% and elongation is increased by 70.8%. Overall, Example 4 is the most balanced in terms of tensile strength, elongation, and fracture toughness (521 MPa, 15%, 34 MPa·m 1 / 2 ), Example 3 is suitable for high-strength applications, and Example 2 and Example 1 are suitable for scenarios with higher toughening and crack resistance requirements.

[0075] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application should not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for producing aluminum alloy powder for additive manufacturing, characterized in that: The steps include: Aluminum and aluminum-based master alloy containing magnesium and manganese elements are put into the melting crucible according to the designed ratio; The crucible is evacuated and then filled with inert gas to form a negative pressure environment; Heating the melting crucible to 700-750° C. to melt the aluminum element and the aluminum-based master alloy to obtain a first melt; Heating the first melt to 800-850° C. to obtain a second melt; preparing the second melt into powder by a gas atomization method; The powder is screened to obtain the aluminum alloy powder having a particle size range of 15-53 μm, wherein the aluminum alloy powder comprises, by mass fraction: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr，0.4%-0.7%； The balance is Al and inevitable impurities.

2. The method for producing aluminum alloy powder according to claim 1, wherein: The aluminum-based master alloys include AlMn master alloys, AlMg master alloys, AlSc master alloys and AlZr master alloys.

3. The method for producing aluminum alloy powder according to claim 1, wherein: The step of "raising the temperature of the melting crucible to 700-750° C." includes: raising the temperature of the melting crucible to 700-750° C. at a heating rate of 10-20° C. / min; The step of "evacuating the melting crucible and then filling it with inert gas to form a negative pressure environment" includes the steps of evacuating the melting crucible to below 0.1 Pa and then filling it with inert gas to a negative pressure state of 99.5 KPa.

4. The method for producing aluminum alloy powder according to claim 1, wherein: The step of heating the first melt to 800-850° C. further includes the following steps: The first melt is electromagnetically stirred at 700-750° C. and kept warm for 10-15 minutes.

5. The method for producing aluminum alloy powder according to claim 4, wherein: The step of "preparing the second melt into powder by a gas atomization method" includes the following steps: The smelting crucible is tilted to allow the second melt to pass into the atomization chamber through the tundish crucible and the draft tube, and high-pressure gas is sprayed in for atomization and powdering. The draft tube is made of boron nitride or zirconium oxide, and the flow restriction port diameter of the draft tube is 3-6 mm. The spray disc in the atomization chamber is an annular seam-type tightly coupled atomizing spray disc, and the atomization pressure of the high-pressure gas is 1.5-4.0 MPa.

6. An aluminum alloy powder produced by the method for producing an aluminum alloy powder for additive manufacturing according to any one of claims 1 to 5, characterized in that: Measured by mass fraction, the aluminum alloy powder comprises: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr，0.4%-0.7%； The balance is Al and inevitable impurities.

7. The aluminum alloy powder according to claim 6, wherein The steel comprises the following components in weight percentage: Mn, 2.3%, Mg, 1.8%, Sc, 0.7%, Zr, 0.6%, and the balance being Al and inevitable impurities.

8. The aluminum alloy powder according to claim 7, wherein The invention comprises the following components in weight percentage: Mn, 1.5%, Mg, 1.6%, Sc, 0.8%, Zr, 0.6%, and the balance is Al and inevitable impurities.

9. The aluminum alloy powder according to claim 7, wherein The invention comprises the following components in weight percentage: Mn, 2.5%, Mg, 2.5%, Sc, 0.8%, Zr, 0.7%, and the balance is Al and inevitable impurities.

10. The aluminum alloy powder according to claim 7, wherein The invention comprises the following components in weight percentage: Mn, 2.0%, Mg, 2.0%, Sc, 0.7%, Zr, 0.6%, and the balance is Al and inevitable impurities.

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