Aluminum alloy powder for additive manufacturing and its manufacturing method

Abstract

This application relates to an aluminum alloy powder for additive manufacturing and a method for manufacturing the same, comprising the following steps: adding elemental aluminum and an aluminum-based master alloy containing magnesium and manganese in a designed ratio into a melting crucible; evacuating the melting crucible and then filling it with an inert gas to create a negative pressure environment; heating the melting crucible to 700-750°C to melt the elemental aluminum 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 using a gas atomization method; and screening the powder to obtain the aluminum alloy powder with a particle size range of 15-53 μm. The aluminum alloy powder manufacturing method provided by this application has the advantage of suppressing the loss of easily burnable elements.

Description

Technical Field

[0001] This 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 Technology

[0002] In laser additive manufacturing, aluminum alloy powder is typically 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) have significant problems. During the high-temperature smelting stage, key elements in aluminum alloys, such as magnesium (Mg) and manganese (Mn), which are easily burned, will suffer severe volatilization losses due to their low boiling points, high vapor pressures, or easy oxidation.

[0004] This burn-off causes the actual chemical composition of the powder to deviate from the design target, especially with insufficient content of reinforcing elements such as Mg and Mn. The consequence is a decrease in powder quality, which ultimately affects the mechanical properties (such as strength and hardness) and process stability of additively manufactured parts, and increases production costs (requiring excessive addition of elements).

[0005] Therefore, there is an urgent need to develop a method for preparing aluminum alloy powder that can effectively suppress the loss of easily burned elements in order to obtain high-performance powder with accurate and stable composition. Summary of the Invention

[0006] This application provides aluminum alloy powder for additive manufacturing and a method for manufacturing the same, in order to solve the technical problem that the volatilization loss of easily burned elements such as magnesium (Mg) and manganese (Mn) during the preparation of aluminum alloy powder causes the chemical composition of the powder to deviate from the design value.

[0007] A method for manufacturing aluminum alloy powder for laser additive manufacturing includes the following steps: Aluminum and an aluminum-based master alloy containing magnesium and manganese are added to a melting crucible according to a designed ratio. The melting crucible is evacuated and then filled with an inert gas to create a negative pressure environment. The melting crucible is heated to 700-750°C to melt the aluminum and the aluminum-based master alloy, obtaining a first melt. The first melt is heated to 800-850°C to obtain a second melt. The second melt is prepared into powder using a gas atomization method. The powder is screened to obtain aluminum alloy powder with a particle size range of 15-53 μm. 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%; with the balance being 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 "heating the melting crucible to 700-750°C" includes: heating the melting crucible to 700-750°C at a heating rate of 10-20°C / min. The step "evacuating the melting crucible and then filling it with inert gas to create 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 state of 99.5 kPa.

[0010] In some possible implementations, the step of "heating the first melt to 800-850°C" is further included by: electromagnetically stirring the first melt and holding it at that temperature for 10-15 minutes.

[0011] In some possible implementations, the step "preparing the second melt into powder using a gas atomization method" includes the steps of: tilting the furnace body to allow the second melt to pass through the tundish crucible and guide pipe into the atomization chamber, while simultaneously injecting high-pressure gas for atomization powder preparation.

[0012] The guide tube is made of boron nitride or zirconium oxide, and the diameter of the flow-limiting orifice of the guide tube is 3-6 mm. The spray disc in the atomization chamber is a circumferentially 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-described aluminum alloy powder manufacturing method comprises the following components by weight percentage: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr, 0.4%-0.7%; with the balance being Al and unavoidable impurities.

[0014] In some possible implementations, the components include the following weight percentages: Mn, 2.3%, Mg, 1.8%, Sc, 0.7%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0015] In some possible implementations, the components include the following weight percentages: Mn, 1.5%, Mg, 1.6%, Sc, 0.8%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0016] In some possible implementations, the components include the following weight percentages: Mn, 2.5%, Mg, 2.5%, Sc, 0.8%, Zr, 0.7%, with the balance being Al and unavoidable impurities.

[0017] In some possible implementations, the components include the following weight percentages: Mn, 2.0%, Mg, 2.0%, Sc, 0.7%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0018] In this application, intermediate alloys with melting points close to pure aluminum (such as AlMn and AlMg) are used instead of pure metals as raw materials. These intermediate alloys can lower the melting temperature and shorten the melting time. Pure metals such as Mn and Zr have melting points much higher than aluminum (660°C), and while Mg has a low melting point, its low boiling point makes it easily volatile. Traditional methods require maintaining temperatures far above the melting point of aluminum (e.g., above 750°C) for extended periods to melt these high-melting-point metals. This provides strong volatilization conditions for low-boiling-point elements such as Mg and Mn, leading to severe burn-off. However, the selected intermediate alloys (e.g., Al-50Mn with a melting point of approximately 710-730°C) have melting points close to those of pure aluminum. Therefore, in a vacuum melting crucible, only a temperature slightly above the melting point of aluminum (e.g., 700-750°C) is needed to rapidly and synchronously melt all raw materials (pure aluminum ingots and various intermediate alloys). This reduces the high-temperature environment required to melt high-melting-point pure metals and further shortens the total time the alloy melt remains in a high-temperature liquid state. Since the degree of elemental volatilization loss is strongly dependent on temperature and time (high temperature and long time aggravate loss), this combination of "low-temperature melting" and "short-time operation" effectively suppresses the volatilization of easily burnable elements such as Mg and Mn during the melting stage, thereby maximizing the retention of target components and improving the chemical stability and precision of the powder. In addition, the inert gas environment further reduces oxidation loss. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

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

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

[0022] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0023] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0024] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. When a component is said to be "set on" another component, it can be directly set on the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Some embodiments of this application are described in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] This application provides a method for manufacturing aluminum alloy powder for additive manufacturing, in order to solve the problem in the prior art that the loss of volatile elements such as magnesium (Mg) and manganese (Mn) is serious, resulting in unstable chemical composition of aluminum alloy powder.

[0028] The aluminum alloy powder manufacturing method includes the following steps:

[0029] S1: Elemental aluminum and an aluminum-based master alloy containing magnesium and manganese are added to a melting crucible according to the designed proportions. The melting crucible may be an alumina crucible or a graphite crucible.

[0030] In this embodiment, the elemental aluminum is a pure aluminum ingot with a purity of Al 99.85% or higher. The aluminum-based master alloy includes AlMn master alloy, AlMg master alloy, AlSc master alloy, and AlZr master alloy.

[0031] The AlMn master alloy includes one of the following grades: AlMn10, AlMn15, AlMn20, AlMn25, AlMn30, and AlMn40. The AlMg master alloy includes one of the following grades: AlMg20, AlMg25, AlMg50, and AlMg60. The AlSc master alloy includes one of the following grades: AlSc2, AlSc5, and AlSc10. The AlZr master alloy includes one of the following grades: AlZr3, AlZr4, AlZr5, AlZr5A, AlZr6, AlZr10, and AlZr10A. The grade designation refers to the commercially available concentration of the main alloying element in the master alloy, typically directly corresponding to the approximate mass percentage content of that element. 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.

[0032] Specifically, in this embodiment, each grade can be understood according to the following table:

[0033] Table 1: Grades of aluminum-based intermediate alloys and their corresponding components and mass percentages

[0034]

[0035] S2: The melting crucible is evacuated and then filled with inert gas to create a negative pressure environment.

[0036] In this embodiment, step S2 includes: first, placing a crucible containing the pre-proportioned aluminum and intermediate alloy into a melting apparatus with a vacuum chamber. A roughing pump is started to rapidly reduce the chamber pressure to approximately 0.1 Pa, then a molecular pump is switched to further reduce the pressure to no higher than 0.1 Pa, in order to maximize the removal of air and moisture. Under this ultra-high vacuum environment, the oxygen partial pressure and water vapor content in the chamber are reduced to extremely low levels, providing initial protection for the reactive elements in the melt.

[0037] After the vacuum reaches the set value, close the vacuum pump interface and slowly open the inert gas (argon or nitrogen) passage. Adjust the chamber pressure to a slight negative pressure of approximately 99.5 kPa using a precision pressure regulating valve. During this process, the inert gas fills the entire melting crucible, maintaining a low-oxygen environment and forming a protective atmosphere to prevent backflow of outside air. Repeating this brief vacuum-filling-gas-filling cycle further ensures that any remaining trace impurities are removed, ultimately meeting the process requirements for suppressing elemental volatilization during subsequent high-temperature melting in a stable, slightly negative pressure inert atmosphere.

[0038] S3: Heat the melting crucible to 700-750°C to melt the elemental aluminum and the aluminum-based master alloy to obtain the first melt.

[0039] In this embodiment, step S3 includes: using a medium-frequency induction melting furnace for melting, gradually increasing the temperature during the melting process at a rate of 10-20℃ / min, and controlling the melting temperature between 700-750℃ to ensure that the elemental aluminum and the aluminum-based master alloy are fully melted to form the first melt. At 700-750℃, an electromagnetic stirrer is turned on for stirring and the temperature is maintained for 10-15 minutes.

[0040] S4: Heat the first melt to 800-850℃ to obtain the second melt.

[0041] After homogenizing the composition of the first melt, the temperature is raised to 800–850℃ primarily to "overheat" the first melt, giving it sufficient fluidity and suitable physical properties to adapt to the subsequent atomization powder production process. Specifically, temperatures above 800℃ significantly reduce the viscosity and surface tension of the aluminum alloy melt, facilitating rapid droplet breakage at the spray plate and the formation of finer, more uniform atomized particles. Simultaneously, moderate overheating allows the second melt to solidify early in the guide tube or spray plate due to insufficient localized temperature, thereby reducing the risk of clogging and particle size fluctuations. In other words, the purpose of the temperature increase in step S4 is to provide a "high-energy state" for the second melt in gas atomization, ensuring controllable powder particle size, regular morphology, and maximizing the stability of the chemical composition.

[0042] S5: The second melt is prepared into powder by gas atomization.

[0043] In this embodiment, step S5 includes: injecting a second melt at 800–850°C into an intermediate ladle crucible equipped with a silicon carbide or zirconium oxide ceramic filter (10 ppi pore size) by tilting the melting crucible to filter and remove small amounts of inclusions in the melt; then, the second melt flows stably into the atomization chamber through a guide tube made of boron nitride or zirconium oxide with a flow restrictor diameter of 4.0–4.5 mm. At this time, a high-pressure inert gas (nitrogen or argon with a purity of 99.999%) at 2.0–3.0 MPa is simultaneously injected through a circumferentially slit-type tightly coupled atomizing spray disc.

[0044] The melt is subjected to high-speed airflow impact and shearing, breaking it into atomized droplets with diameters of 15–53 μm. During this process, a filter ensures the purity of the melt, a flow guide maintains a stable flow rate, and the spray disc and air pressure jointly determine the strength of the atomizing shear force, thereby controlling the droplet formation rate and size distribution. Ultimately, near-spherical, uniformly distributed aluminum alloy powder is formed under high temperature and high speed.

[0045] S6: Screen the powder to obtain aluminum alloy powder with a particle size range of 15-53μm.

[0046] In this embodiment, step S6 includes: First, the coarse powder obtained from atomization is fed into an air classifier protected by inert gas. Utilizing the centrifugal retention principle of an adjustable rotor, the powder is separated into coarse and fine parts under the action of airflow. Large particles that do not meet the standards are discharged from the classifier outlet and returned to the furnace, while the fine powder enters the collection system with the airflow. During operation, the particle size separation point can be precisely set by adjusting the inlet airflow velocity and the rotation speed of the classifier wheel. After multiple cycles of classification, aluminum alloy powder with a particle size concentrated in the range of 15–53 μm can be obtained. The particle size distribution of the finished powder, as measured by a laser particle size analyzer, is D10: 15–25 μm, D50: 30–40 μm, D90: 50–65 μm. Under optimized conditions, it reaches D10: 17–23 μm, D50: 30–40 μm, D90: 45–53 μm, ensuring that the powder possesses both good flowability and spreadability while meeting the fineness and sphericity requirements of additive manufacturing. Specifically, D10 represents 10% of the total mass of particles smaller than this value; D50 represents 50% of the total mass of particles smaller than this value; and D90 represents 90% of the total mass of particles smaller than this value.

[0047] Compared with existing technologies, the manufacturing method provided in this application has the following advantages:

[0048] (1) The preparation method of this application uses an intermediate alloy with a melting point close to that of pure aluminum as raw material, reducing the melting time and greatly reducing the loss of easily burned elements such as Mg and Mn. Pure metals such as Mn and Zr have melting points much higher than aluminum (660°C), and although Mg has a low melting point, it has a low boiling point and is easily volatile. Traditional methods require maintaining a temperature much higher than the melting point of aluminum (such as above 750°C) for a long time to melt these high-melting-point metals, which provides strong volatilization conditions for low-boiling-point elements such as Mg and Mn, resulting in serious burn-off. However, the selected intermediate alloy (such as Al-50Mn with a melting point of about 710-730°C) has a melting point close to that of pure aluminum. Therefore, in a 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 rapidly and synchronously. In this way, the high-temperature environment required to melt 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 degree of element volatilization loss is strongly dependent on temperature and time (high temperature and long time aggravate 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 maximizing the retention of target components and improving the chemical stability and accuracy of powder.

[0049] (2) The preparation method of this application uses electromagnetic stirring to promote the homogenization of alloying elements and reduce the compositional segregation caused by the density difference of different elements.

[0050] (3) The preparation method of this application achieves the optimal yield and quality of 15-53μm finished powder by reasonably adjusting and controlling the powder process parameters such as melt temperature, guide tube diameter, and atomizing gas pressure.

[0051] (4) The preparation method of this application uses an inert gas protective air classifier to classify the powder, which can reduce the oxidation of the powder and make the particle size control of the aluminum alloy powder more precise.

[0052] An aluminum alloy powder manufactured by the above-described aluminum alloy powder manufacturing method comprises the following components by weight percentage: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr, 0.4%-0.7%; with the balance being Al and unavoidable impurities.

[0053] Furthermore, it comprises the following components by weight percentage: Mn, 2.3%, Mg, 1.8%, Sc, 0.7%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0054] Furthermore, it comprises the following components by weight percentage: Mn, 1.5%, Mg, 1.6%, Sc, 0.8%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0055] Furthermore, it comprises the following components by weight percentage: Mn, 2.5%, Mg, 2.5%, Sc, 0.8%, Zr, 0.7%, with the balance being Al and unavoidable impurities.

[0056] Furthermore, it comprises the following components by weight percentage: Mn, 2.0%, Mg, 2.0%, Sc, 0.7%, Zr, 0.6%, with the balance being Al and unavoidable impurities.

[0057] The addition of Mn and Mg elements primarily serves as solid solution strengthening. By rationally adjusting the content of Mn and Mg, their solid solution strengthening effects are synergistic. This reduces the precipitation of large, brittle Mg2Si and Al6Mn second phases due to excessive Mn and Mg content, and also avoids the printing defects caused by excessive Mg content, which can lead to porosity and a large amount of spatter. The addition of Sc and Zr elements preferentially precipitates nano-sized Al3Sc and Al3Zr particles or composite components during solidification, acting as nucleation sites for aluminum-based heterogeneous materials and refining the grain size. Simultaneously, during the aging heat treatment of the product, the supersaturated solid solution precipitates fine second-phase particles, resulting in precipitation strengthening.

[0058] The present application will be described in detail below with reference to representative embodiments to help understand the spirit and essence of the present application, but without limiting the scope of the present application in any way.

[0059] Example 1

[0060] A laser additive manufacturing aluminum alloy powder is composed of the following components by mass percentage: Mn 2.3%, Mg 1.8%, Sc 0.7%, Zr 0.6%, with the balance being Al and unavoidable impurities. The specific preparation process is as follows: (1) Place the weighed 99.85% pure aluminum ingot, AlMn10 master alloy, AlMg20 master alloy, AlSc2 master alloy, and AlZr5A master alloy into a vacuum melting crucible; (2) Evacuate the powder preparation equipment to below 0.1 Pa, and then add inert gas to a slightly negative pressure state of 99.5 Kpa. Repeat the above evacuation and gas filling three times; (3) Turn on the medium frequency induction melting power supply, and gradually increase the melting power every 10 min: 15 Kw / 10 min, 30 Kw / 10 min, 50 Kw / 10 min, 80 Kw until it is completely melted. , readjust the power to 50Kw and perform temperature control to keep the melting temperature at 700-750℃; (4) after all the raw materials are melted to the molten state, turn on the electromagnetic stirrer and keep it warm for 12 minutes; (5) after the heat preservation is completed, adjust the power to 80Kw to heat the melt. When the melt temperature reaches 830℃ and the intermediate ladle temperature is 850℃, immediately tilt the furnace body for pouring. The diameter of the guide pipe is 4mm, and 2.5Mpa argon gas is injected at the same time for atomization powder making; (6) classify the powder obtained by atomization through an inert gas protective airflow classifier to obtain 15-53μm powder required for additive manufacturing.

[0061] Examples 2-4

[0062] The difference from Example 1 lies in the different component contents of the aluminum alloy powders in Examples 2-4, expressed as mass percentages, as shown in Table 2. The preparation methods of the aluminum alloy powders in Examples 2-4 are the same as those in Example 1.

[0063] Table 2. Mass percentage of the components of aluminum alloy powders in Examples 2-4 (%)

[0064]

[0065] Comparative Examples 1 and 2

[0066] An aluminum alloy powder for laser additive manufacturing is produced using the same method as in Example 1. The difference lies in the composition and mass percentage content of the aluminum alloy powder, as shown in Table 3.

[0067] Table 3. Mass percentage of the components of aluminum alloy powders in Comparative Examples 1 and 2 (%)

[0068]

[0069] Comparative Example 3

[0070] A method for manufacturing aluminum alloy powder for laser additive manufacturing, wherein the chemical composition is consistent with that in Example 1. The specific method is as follows: (1) Place the weighed 99.85% pure aluminum ingot, AlMn10 master alloy, AlMg20 master alloy, AlSc2 master alloy, and AlZr5A master alloy into a vacuum melting crucible; (2) Evacuate the powder making equipment to below 20 Pa, and then add inert gas to a slightly negative pressure state of 99.5 Kpa; (3) Turn on the medium frequency induction melting power supply, and gradually increase the melting power every 10 min: 15 Kw / 10 min, 30 Kw / 10 min, 50 Kw / 10 min, 80 Kw After complete melting, the power is readjusted to 50Kw and temperature control is performed to keep the melting temperature at 800-850℃; (4) After the heat preservation is completed, the power is adjusted to 80Kw to heat the melt. When the melt temperature reaches 900℃ and the intermediate ladle temperature is 850℃, the furnace body is immediately tilted for pouring. The diameter of the guide pipe is 5mm, and 5.0Mpa argon gas is injected at the same time for atomization powder making; (5) The powder obtained by atomization is classified by an inert gas protective airflow classifier to obtain 15-53μm powder required for additive manufacturing.

[0071] The preparation methods of Example 1 and Comparative Example 3 differ as follows: (I) In Example 1, the vacuum level was first evacuated to ≤0.1 Pa using a mechanical pump and a molecular pump in two stages, then argon gas was introduced to a slight negative pressure of 99.5 kPa, and the "vacuuming-ventilation" cycle was repeated three times to remove oxygen and moisture to the maximum extent. In Comparative Example 3, the chamber was only evacuated to 20 Pa and then ventilated once, without deep vacuum or a cycle. (II) In Example 1, the power was increased in stages (15 kW → 30 kW → 50 kW → 80 kW) until melting, and then the power was reduced back to 50 kW for precise temperature control, so that the melting temperature was stabilized at 700–750 ℃. In Comparative Example 3, the power was increased in stages to 80 kW, but the melting temperature was controlled in the 800–850 ℃ range without a reduction stage. (III) In Example 1, an electromagnetic stirrer was turned on and stirred continuously for 12 minutes in the 700–750 ℃ ​​holding range to ensure uniform melt composition. In Comparative Example 3, no stirring or special holding and homogenization steps were involved. (iv) In Example 1, after the heat preservation period, the melt was heated to approximately 830°C (80kW), and the temperature of the tundish crucible was approximately 850°C before atomization. In Comparative Example 3, the melt was heated to 900°C before atomization. (v) In Example 1, the diameter of the guide tube was 4.0–4.5 mm, and the material was boron nitride or zirconium oxide; a circumferentially slit-type tightly coupled spray disc was used with 2.0–3.0 MPa inert gas. In Comparative Example 3, the diameter of the guide tube was 5 mm, and the spray gas pressure was 5.0 MPa. (vi) In Example 1, an air classifier was used under inert gas protection, and multiple cycles were performed to obtain a particle size concentrated in the range of 15–53 μm. Comparative Example 3 also performed classification but did not emphasize multiple cycles, nor did it finely adjust the classification parameters.

[0072] In summary, Example 1 has undergone meticulous design and multiple cycles of optimization in key aspects such as vacuum protection, melting temperature control, melt stirring, superheating temperature and spray parameters, and classification and screening, in order to systematically suppress the loss of volatile elements and improve powder purity and morphological uniformity. In contrast, Comparative Example 3 simplifies or adopts more "aggressive" high temperature and high pressure parameters in many places, which may sacrifice component control and powder quality, resulting in its sphericity, component stability and classification effect being inferior to Example 1.

[0073] The properties of the aluminum alloy powders prepared by the preparation methods in Examples 1-4 and Comparative Examples 1-3 of this application were tested, analyzed, and evaluated.

[0074] (a) Performance testing of aluminum alloy powder:

[0075] According to GB / T39251 "Characteristics of properties of additive manufacturing metal powder", the properties of 15~53μm aluminum alloy powders prepared in the examples and comparative examples are compared, as shown in Table 4.

[0076] Table 4 Comparison of aluminum alloy powder properties between the implemented case and the comparative example

[0077]

[0078] Regarding the component content, as shown in Table 4 for Examples 1-4 and Comparative Examples 1-2, the formulations of the Examples (Mn 1.5–2.5%, Mg 1.6–2.5%, Sc 0.5–0.8%, Zr 0.4–0.7%) exhibited, on average, lower oxygen content (152 ppm vs 180 ppm, a decrease of 15.6%), smaller angle of repose (31.25° vs 34.00°, a decrease of 8.1%), lower hollow powder ratio (0.975% vs 1.25%, a decrease of 2%), and slightly higher bulk density and sphericity compared to Comparative Examples 1-2. The high Mg ratio (Comparative Example 2, Mg 4.5%) led to increased oxygen, decreased sphericity, increased hollowness, and poor flowability, indicating that excessive Mg at this process window amplifies oxidation / volatilization and poor forming.

[0079] Regarding the manufacturing method, as shown in Tables 4 (Examples 1-4 and Comparative Example 3), Example 1, through deep vacuum multiple filling, temperature control at 700-750℃ with stirring and homogenization, moderate overheating, and optimized atomization / classification, reduced the oxygen content from 280ppm to 154ppm (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 loose / tap density increased by 23% and 9%, respectively. Although the yield of the target particle size range was 5 percentage points lower than that of Comparative Example 3, the overall powder quality was significantly improved.

[0080] (II) Comparative analysis of SEM morphology of gold powder:

[0081] The following section uses two SEM topography images to illustrate Example 1 ( Figure 1 ) and Comparative Example 3 ( Figure 2 By comparing the morphological characteristics of the aluminum alloy powders obtained, it can be found that:

[0082] 1. Sphericity and overall morphology

[0083] Example 1 ( Figure 1 The powder particles are highly spherical, with almost no visible traces of severe stretching or deformation. The vast majority of particles have smooth, intact outlines, indicating a good balance between shear force and surface tension during atomization, breakup, and solidification. Comparative Example 3 ( Figure 2 Although round particles are visible, there are many irregular, flat "teardrop" shapes or agglomerates with uneven surface contours, indicating that some droplets condensed or adhered early during atomization or rapid solidification.

[0084] 2. Surface quality and spatter

[0085] Example 1: The particle surface is relatively clean, with only a few scattered "satellite balls" (attached tiny satellite particles) or a very small number of protrusions, indicating that the intermediate pack filter and guide tube scheme effectively removed large-sized inclusions. The inert gas and high-temperature overheating caused the droplets to solidify smoothly. Comparative Example 3: The surface is covered with clumps of spatter of varying sizes, as well as a large number of attached satellite balls, severely affecting powder flowability and uniformity. This may be because the smaller guide hole diameter and moderate air pressure in Example 1 generate more ideal shear force, resulting in a more uniform droplet size. While the excessively high spray pressure in Comparative Example 3 can form finer powder, it easily causes more spatter and satellite ball attachment.

[0086] 3. Size distribution and grading effect

[0087] Example 1: Figure 1 The visible particle diameters are mostly concentrated in the range of 20–50 μm (approximately 1–3 times the 50 μm scale in the figure), and the particle size distribution at the edges is relatively concentrated, with no obvious large particles or agglomerates. Comparative Example 3: Figure 2 Numerous large aggregates exceeding 50 μm and several small particles <15 μm are visible, indicating a wide particle size distribution and suggesting insufficient efficiency in the grading and screening process.

[0088] 4. Holes and internal defects

[0089] Example 1: Figure 1Very few open or hollow particles were observed in the powder; the powder particles were well-solidified. This is closely related to vacuum-inert gas protection and precise temperature control, which reduces the dissolution and precipitation of gases in the melt. Comparative Example 3: Figure 2 The presence of obvious pores or depressions on the surface of some powder particles (hollow powder) indicates that during the melt injection and rapid solidification stages, the gas was trapped inside the powder before it could escape.

[0090] In summary, the aluminum alloy powder prepared in Example 1 has a regular morphology, high sphericity, smooth surface, narrow particle size distribution, and no obvious hollow powder, which greatly improves the powder flowability and uniformity of subsequent laser powder spreading. In contrast, Comparative Example 3 has defects such as low sphericity, more spatter, wide particle size distribution, and high hollow powder rate, all of which are not conducive to high-quality laser additive manufacturing.

[0091] (III) Mechanical property testing of the printed parts:

[0092] The following describes the printing tests and analysis of the aluminum alloy powders manufactured in Examples 1-4 and Comparative Examples 1-3 of this application.

[0093] The aluminum alloy powders obtained in Examples 1-4 and Comparative Examples 1-3 were used for printing tests on an HBDP400 printing equipment to test the performance of the printed parts. This equipment is a selective laser melting equipment, and the printing process parameters are: laser power of 300W, printing layer thickness of 40μm, scanning spacing of 0.1mm, and laser scanning speed of 1000mm / s.

[0094] After printing, the printed parts undergo heat treatment to reduce residual stress and improve precipitation strengthening. The heat treatment process is as follows: heat from room temperature to 325°C for 1 hour, hold at 325°C for 2 hours, and then remove and air cool.

[0095] The mechanical properties of the printed parts were tested. The room temperature tensile properties (strength and elongation) were tested according to GB / T228.1-2021, and the fracture toughness was tested according to GB / T4161-2007. The results are shown in Table 5.

[0096] Table 5 Comparison of mechanical properties of printed parts from the examples and comparative examples.

[0097]

[0098] As shown in Tables 4 and 5, under the condition of a fixed composition, the powder preparation method of Example 1 and Comparative Example 3 can be analyzed to show that the powder preparation method of the examples can significantly improve the plasticity and toughness of the printed parts. Specifically, the elongation increased from 12% to 18.5% (an increase of 54%), and the fracture toughness increased from 20.5 to 39 MPa·m. 1 / 2(Increased by 90%); tensile strength increased from 520 MPa to 480 MPa (decreased by 7.7%). This result is consistent with the significant decrease in oxygen content, improved sphericity, and reduced hollow powder ratio shown in Table 4, indicating that the powder preparation process of Example 1 of this application can suppress the burn-off of key elements such as Mg, Mn, Sc, and Zr, reduce oxygen content and brittle inclusions, improve element retention to ensure the strengthening and toughening effect of the microstructure, thereby improving the crack propagation resistance.

[0099] As shown in Tables 4 and 5, under the same powdering method, the formulations of Examples 1-4 generally exhibit higher elongation and fracture toughness compared to Comparative Examples 1-2, and can achieve a balance under different strength targets: Equal strength, improved plasticity and 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 formulation (Example 3 vs. Comparative Example 2): strength is increased by 11.9%, and elongation and fracture toughness are increased simultaneously; High-toughness formulation (Example 2 vs. Comparative Example 2): fracture toughness is increased by 110%, and elongation is increased by 70.8%. Overall, Example 4 shows the most balanced performance 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, while Example 2 and Example 1 are suitable for scenarios with higher requirements for toughening and crack resistance.

[0100] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A method for manufacturing aluminum alloy powder for additive manufacturing, characterized in that, Includes the following steps: Elemental aluminum and aluminum-based master alloys containing magnesium and manganese are added to the melting crucible according to the designed proportions. The melting crucible is evacuated and then filled with inert gas to create a negative pressure environment. The melting crucible is heated to 700-750°C to melt the elemental aluminum and the aluminum-based master alloy, thereby obtaining a first melt. The first melt is heated to 800-850℃ to obtain the second melt; The second melt was prepared into powder using a gas atomization method; The powder was screened to obtain aluminum alloy powder with a particle size range of 15-53 μm. The aluminum alloy powder, by mass fraction, comprises: Mn, 1.5%-2.5%; Mg, 1.5%-2.5%; Sc, 0.5%-0.8%; Zr，0.4%-0.7%； The balance consists of Al and unavoidable impurities.

2. The method for manufacturing aluminum alloy powder as described in claim 1, characterized in that, The aluminum-based master alloys include AlMn master alloy, AlMg master alloy, AlSc master alloy, and AlZr master alloy.

3. The method for manufacturing aluminum alloy powder as described in claim 1, characterized in that, The step of "heating the melting crucible to 700-750°C" includes: heating the melting crucible to 700-750°C at a heating rate of 10-20°C / min; The step "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 manufacturing aluminum alloy powder as described in claim 1, characterized in that, The step preceding the step "heating the first melt to 800-850°C" also includes the following step: The first melt is electromagnetically stirred at 700-750℃ and kept at that temperature for 10-15 minutes.

5. The method for manufacturing aluminum alloy powder as described in claim 4, characterized in that, The step of "preparing the second melt into powder using a gas atomization method" includes the following steps: The melting crucible is tilted so that the second melt is passed through the tundish crucible and the guide pipe into the atomization chamber. At the same time, high-pressure gas is injected for atomization and powdering. The guide pipe is made of boron nitride or zirconium oxide and the diameter of the flow limiting port of the guide pipe is 3-6 mm. The spray disc in the atomization chamber is a ring-slit tightly coupled atomizing spray disc. The atomization pressure of the high-pressure gas is 1.5-4.0 MPa.

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