A preparation method of spherical tungsten alloy powder for 3D printing

Abstract

The present invention provides a method for preparing spherical tungsten alloy powder for 3D printing, belonging to the technical field of metal additive manufacturing. In the present invention, fine-grained tungsten powder and tungsten oxide powder are mixed as a composite tungsten source, and the spray-dried precursor agglomerates are subjected to wet hydrogen reduction by utilizing the volatilization-deposition characteristics during the hydrogen reduction of tungsten oxide to achieve the purpose of auxiliary sintering. The reduced tungsten alloy intermediate powder inherits the spherical morphology of spray drying, and the cohesive strength is significantly improved. At the same time, the interior of the particles remains a loose and porous structure, which can not only effectively ensure the stability of the plasma spheroidization powder feeding process, is more likely to absorb and transfer heat in the plasma torch, reduce energy consumption in actual production, and obtain higher spheroidization efficiency and sphericity.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and particularly relates to a method for preparing spherical tungsten alloy powder for 3D printing. Background Art

[0002] Refractory metal tungsten and its alloys have excellent properties such as high melting point, high hardness, high high-temperature strength, high elastic modulus, low thermal expansion coefficient, good electrical conductivity and corrosion resistance, and are widely used in cutting-edge fields such as aerospace, national defense, nuclear industry, medical equipment, and electronics. Powder metallurgy is the most commonly used method for preparing tungsten alloys. However, due to the relatively large brittleness of tungsten alloys at room temperature, it is difficult to prepare parts with complex structural features such as thin walls, curved surfaces, and porous structures by conventional powder metallurgy methods, which limits the wider application of tungsten alloy materials in the industrial field. Compared with traditional powder metallurgy methods, 3D printing has unique technical advantages such as high material utilization rate, high manufacturing flexibility, small machining allowance, few structural design constraints, near-net shaping of parts with complex structures, and rapid response to structural design changes, and has become one of the hotspots in the current preparation and production of tungsten alloy materials.

[0003] Powder bed fusion and direct energy deposition are the two most commonly used 3D printing technologies for tungsten alloy additive manufacturing. The morphology and particle size of the raw powder are important factors affecting the performance of 3D printed tungsten alloy formed parts. Compared with irregular powders, spherical powders have a higher energy absorption rate, which is beneficial to the formation of continuous scanning trajectories and the densification of formed parts. Whether it is powder bed fusion or direct energy deposition, the raw powder needs to meet the requirements of high sphericity, good fluidity, high loose density, small particle size, and narrow particle size distribution. With the increasing demand for tungsten alloy parts with complex and precise structures in industries such as medical equipment and electronic information, and the urgent requirements for rapid prototyping of high-performance tungsten alloy parts in fields such as aerospace and weaponry, spherical powder, as the core material, has become the greatest value in tungsten alloy 3D printing additive manufacturing.

[0004] Laser 3D printing powders generally require spherical powders with a particle size range of 5 - 250 μm. Existing technologies usually use various molten metal atomization methods to produce spherical powders that meet the 3D printing particle size requirements, but such methods are mainly used to produce low-melting-point metal and alloy powders, such as copper powder, aluminum powder, nickel powder, and stainless steel powder, etc., and are powerless for high-melting-point metals, alloys, and ceramics. In the existing technology, radio frequency plasma spheroidization is used to spheroidize high-melting-point metals and alloys. However, plasma spheroidization requires the preparation of precursor particles with a certain fluidity, uniformity, and agglomeration degree to ensure the plasma spheroidization effect. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method for spherical tungsten alloy powder for laser 3D printing, which has good sphericity and fluidity, high density, and uniform distribution of alloy components, aiming at the above-mentioned requirements.

[0006] To achieve the above object of the invention, the present invention provides the following technical solutions:

[0007] A preparation method for spherical tungsten alloy powder for 3D printing, comprising the following steps:

[0008] Step 1: According to the composition design ratio of the tungsten alloy, a tungsten source powder composed of fine-grained tungsten powder and tungsten oxide powder, elemental alloy powder, a solvent, a dispersant, and a binder are ball-milled and mixed to prepare a stable slurry with a solid content of 50% - 85%, and the slurry is spray-dried and spheronized by a centrifugal spray drying device.

[0009] Step 2: Using a multi-temperature zone tubular reduction furnace equipment commonly used in industrial production, wet hydrogen reduction-assisted sintering treatment is carried out on the spheronized and granulated powder obtained in Step 1. The reduction adopts the following two processes:

[0010] A) Wet hydrogen - dry hydrogen isothermal reduction: In the reduction process, humidified hydrogen and dry hydrogen are introduced in 2 stages respectively. The reduction temperature is 750 - 880 °C. Among them, the hydrogen dew point in the first stage is -15 - 20 °C, the flow rate is 10 - 25 m / min, the reduction time is 20 - 40 min, the hydrogen dew point in the second stage is ≤ -50 °C, the flow rate is 30 - 50 m / min, and the reduction time is 30 - 80 min; this process is suitable for the rapid development of tungsten alloy powders with different compositions.

[0011] B) Stepwise temperature-rising wet hydrogen reduction: The reduction process adopts stepwise temperature-rising, and humidified hydrogen is introduced in both stages. The reduction temperature in the first stage is 700 - 860 °C, the reaction time is 20 - 50 min, the reduction temperature in the second stage is 890 - 1100 °C, the reaction time is 30 - 70 min; the hydrogen dew point is -40 - -10 °C, and the hydrogen flow rate is 30 - 55 m / min, which is suitable for continuous production.

[0012] Step 3: The reduced intermediate powder is subjected to plasma spheronization treatment, and after classification, tungsten alloy powder suitable for laser 3D printing is obtained.

[0013] Further, in Step 1, the average particle size of the fine-grained tungsten powder is 0.1 - 5 μm, the tungsten oxide powder is selected from one of yellow tungsten, purple tungsten, and blue tungsten, with an average particle size of 0.02 - 2 μm, and the mass ratio of tungsten powder to tungsten oxide is 4:1 - 10:1.

[0014] Further, in Step 1, the alloy element is one or more of transition metal elements, and the average particle size of the elemental alloy powder is 0.2 - 10 μm.

[0015] Furthermore, this method is also applicable to molybdenum alloy powders. When preparing molybdenum alloy powders, only the molybdenum source needs to be replaced with fine-grained molybdenum powder and molybdenum oxide powder within the same particle size range.

[0016] In step one of the present invention, the solvent can be anhydrous ethanol or other conventional ball-milling solvents in the field. The dispersant and binder can be polyethylene glycol, polyethylene, polypropylene, polyvinyl alcohol, or polytetrafluoroethylene, etc. that are conventional in this field. Classification can be carried out by conventional screening or air classification, etc.

[0017] Technical effects and advantages of the present invention:

[0018] (1) The present invention uses wet milling to mix and prepare spray-dried slurries, which can effectively solve the problems of component segregation and agglomeration caused by differences in raw material powder density and size, achieve uniform mixing and dispersion distribution of alloy components, and ensure the compositional uniformity and microstructural uniformity of plasma-spheroidized tungsten alloy powders.

[0019] (2) By adjusting spray-drying parameters such as slurry concentration, tungsten source ratio, and rotational speed of the centrifugal atomization nozzle, the particle size of tungsten alloy precursor agglomerates can be flexibly controlled. The spherical tungsten alloy powder products after spheroidization can be widely applied to various near-net-shape manufacturing technologies such as laser powder bed fusion, laser solid forming, electron beam powder bed fusion, and injection molding.

[0020] (3) The present invention uses a mixture of fine-grained tungsten powder and tungsten oxide powder as a composite tungsten source. Utilizing the volatilization-deposition characteristics of tungsten oxide during wet hydrogen reduction, sintering can be achieved by subjecting the spray-dried precursor agglomerates to wet hydrogen reduction. It can effectively maintain the spherical morphology of the spray-dried powder particles. At the same time, it can significantly improve the cohesive strength of tungsten alloy agglomerates. The obtained intermediate powder has good fluidity and is not easily broken, which can effectively ensure the stability of the plasma-spheroidized powder feeding process.

[0021] (4) The tungsten alloy agglomerate intermediate powder obtained by wet hydrogen reduction-assisted sintering, due to the addition of tungsten oxide, is more porous and has a higher specific surface area than the spherules obtained by direct sintering of conventional metal powders after wet hydrogen reduction-assisted sintering. It is more likely to absorb and transfer heat in the plasma torch, with a low temperature gradient inside the particles and high energy utilization efficiency. In actual production, energy consumption can be reduced, and higher spheroidization efficiency and sphericity can be obtained.

[0022] (5) Molybdenum oxide and tungsten oxide have similar volatilization-deposition characteristics during wet hydrogen reduction. The preparation method of the present invention is also applicable to the preparation of molybdenum alloys, and only the molybdenum source needs to be replaced with fine-grained molybdenum powder and molybdenum oxide powder within the same particle size range. Description of the Drawings

[0023] Figure 1 Spherical tungsten powder for 3D printing with a size of 5 - 25 μm prepared in Example 1 (a low magnification; b high magnification);

[0024] Figure 2 97W-2Ni-Fe powder for 3D printing with particle size of 15 - 53 μm prepared in Example 2 (a low magnification; b high magnification);

[0025] Figure 3 Spherical W-50Mo powder for 3D printing with particle size of 53 - 105 μm prepared in Example 3 (a low magnification SEM of the intermediate powder after reduction; b high magnification SEM of the intermediate powder after reduction; c low magnification SEM of the spherical W-50Mo powder; d high magnification SEM of the spherical W-50Mo powder);

[0026] Figure 4 Morphology of spherical tungsten powder for 3D printing with particle size of 5 - 25 μm prepared in Comparative Example 1 without addition of tungsten oxide;

[0027] Figure 5 Morphology of spherical tungsten powder for 3D printing with particle size of 5 - 25 μm prepared in Comparative Example 2 without wet hydrogen reduction-assisted sintering. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1: Preparation of spherical tungsten powder for 3D printing with particle size of 5 - 25 μm.

[0030] According to the mass ratio of tungsten to tungsten trioxide being 4:1, 2 kg of W powder with an average particle size of 0.5 μm and 0.5 kg of tungsten trioxide with an average particle size of 0.02 μm are ball-milled and mixed with 37.5 g of polyethylene glycol and 1071 g of absolute ethanol to prepare a stable slurry with a solid content of 70%. Spray drying and granulation are carried out through a centrifugal spray drying device to obtain precursor powder. The spray drying process is as follows: inlet air temperature 180 °C, atomizer rotation speed 18000 rpm. In a multi-temperature zone tubular reduction furnace equipment, the precursor powder is reduced by a wet hydrogen-dry hydrogen isothermal reduction process. The reduction process is as follows: First, under a humid hydrogen atmosphere, it is reduced at 850 °C for 30 min, the hydrogen dew point is -10 °C, and the flow rate is 15 m / min; then, under a dry hydrogen atmosphere, it is reduced at 850 °C for 60 min, the hydrogen dew point is -60 °C, and the flow rate is 40 m / min. The reduced intermediate powder is processed by plasma spheroidization, and spherical tungsten powder for 3D printing with a size of 5 - 25 μm is obtained after classification. The plasma spheroidization process is as follows: powder feeding rate 37.5 g / min, power 40 KW, side gas 1 (argon) 52 slpm, central gas (argon) 19.5 slpm, side gas 2 (hydrogen) 10 slpm, carrier gas (argon) 4.5 slpm, pressure 15 psi. The morphology and properties of the spherical tungsten powder for 3D printing with a size of 5 - 25 μm are as Figure 1 shown in Table 1.

[0031] Table 1 Properties of Spherical Tungsten Powder for 3D Printing with a Size of 5 - 25 μm

[0032] Powder composition <![CDATA[Density (g / cm 3 )]]> <![CDATA[Bulk density (g / cm 3 )]]> Flowability (s / 50g) Oxygen content Particle size distribution W 19.11 9.92 9.7 0.0181% <![CDATA[D 10 = 7.2 µm D 50 = 15.9 µm D 90 = 22.1 µm]]>

[0033] Example 2: Preparation of spherical tungsten-nickel-iron powder for 3D printing with a size of 15 - 53 μm.

[0034] According to the mass ratio of tungsten to tungsten trioxide being 5:1, 2 kg of W powder with an average particle size of 0.5 μm, 0.4 kg of tungsten trioxide with an average particle size of 0.02 μm, 48 g of nickel powder with an average particle size of 1 μm, and 24 g of iron powder are ball-milled and mixed with 47.8 g of polyethylene glycol and 1287 g of absolute ethanol to prepare a stable slurry with a solid content of 65%. Spray drying granulation is carried out through a centrifugal spray drying device to obtain precursor powder. The spray drying process is as follows: inlet air temperature 170 °C, atomizer rotation speed 15000 rpm. In a multi-temperature zone tubular reduction furnace equipment, the precursor powder is reduced by a staged heating wet hydrogen reduction process. The reduction process is as follows: under a humid hydrogen atmosphere, it is reduced at 800 °C for 30 min and at 1050 °C for 60 min, with a hydrogen dew point of -20 °C and a flow rate of 50 m / min. The reduced intermediate powder is processed by plasma spheroidization, and after classification, spherical 97W-2Ni-Fe powder for 3D printing with a size of 15 - 53 μm is obtained. The plasma spheroidization process is as follows: powder feeding rate 50 g / min, power 40 KW, side gas 1 (argon) 52 slpm, central gas (argon) 19.5 slpm, side gas 2 (hydrogen) 8 slpm, carrier gas (argon) 4.5 slpm, pressure 15 psi. The morphology and properties of the 97W-2Ni-Fe powder for 3D printing with a size of 15 - 53 μm are as Figure 2 shown in Table 2.

[0035] Table 2 Properties of 97W-2Ni-Fe Powder for 3D Printing with a Size of 15 - 53 μm

[0036] Powder composition <![CDATA[Density (g / cm 3 )]]> <![CDATA[Bulk density (g / cm 3 )]]> Flowability (s / 50g) Oxygen content Particle size distribution 97W-2Ni-Fe 18.23 9.11 10.34 0.0446% <![CDATA[D 10 = 19.2 µm D 50 = 37.8 µm D 90 = 46.6 µm]]>

[0037] Example 3: Preparation of spherical tungsten-molybdenum powder for 3D printing with a size of 53 - 105 μm.

[0038] According to the mass ratio of molybdenum to molybdenum oxide being 4:1, 1.2 kg of Mo powder with an average particle size of 0.5 μm, 0.3 kg of molybdenum oxide with an average particle size of 0.1 μm, 1.4 kg of W powder with an average particle size of 1 μm, 58 g of polyethylene glycol, and 1243 g of absolute ethanol were ball-milled and mixed to prepare a stable slurry with a solid content of 70%. Spray drying granulation was carried out through a centrifugal spray drying device to obtain a precursor powder. The spray drying process was as follows: inlet air temperature 160 °C, atomizer rotation speed 10,000 rpm. In a multi-temperature zone tubular reduction furnace equipment, the precursor powder was reduced by a staged temperature rise wet hydrogen reduction process. The reduction process was as follows: under a humid hydrogen atmosphere, it was reduced at 850 °C for 30 min and at 1050 °C for 60 min, with a hydrogen dew point of -30 °C and a flow rate of 50 m / min. The reduced intermediate powder was treated by plasma spheroidization, and after classification, spherical W-50Mo powder for 3D printing with a size of 53 - 105 μm was obtained. The plasma spheroidization process was as follows: powder feeding rate 50 g / min, power 40 KW, side gas 1 (argon) 52 slpm, central gas (argon) 19.5 slpm, side gas 2 (hydrogen) 9 slpm, carrier gas (argon) 4.5 slpm, pressure 15 psi. The morphology and properties of the spherical W-50Mo powder for 3D printing with a size of 53 - 105 μm are as Figure 3 shown in Table 3 and Figure 3 (a) and (b) are the intermediate powders obtained by reduction sintering, Figure 3 (c) and (d) are the spherical tungsten molybdenum powders for 3D printing obtained after plasma spheroidization.

[0039] Table 3 Properties of Spherical W-50Mo Powder for 3D Printing with a Size of 53 - 105 μm

[0040] Powder composition <![CDATA[Density (g / cm 3 )]]> <![CDATA[Bulk density (g / cm 3 )]]> Flowability (s / 50g) Oxygen content Particle size distribution W-50wt.%Mo 13.21 6.93 10.22 0.0242% <![CDATA[D 10 =58.4 µmD 50 =82.6 µmD 90 =99.1 µm]]>

[0041] Comparative Example 1: Spherical tungsten powder for 3D printing with a size of 5 - 25 μm was prepared without adding tungsten oxide.

[0042] According to the mass ratio of tungsten to tungsten trioxide being 4:1, 2 kg of W powder with an average particle size of 0.5 μm and 0.5 kg of tungsten trioxide with an average particle size of 0.02 μm are ball-milled and mixed with 37.5 g of polyethylene glycol and 1071 g of absolute ethanol to prepare a stable slurry with a solid content of 70%. Spray drying granulation is carried out through a centrifugal spray drying device to obtain a precursor powder. The spray drying process is as follows: inlet air temperature 180 °C, atomizer rotation speed 18,000 rpm. In a multi-temperature zone tube-type reduction furnace equipment, the precursor powder is reduced by a wet hydrogen-dry hydrogen isothermal reduction process. The reduction process is as follows: First, it is reduced at 850 °C for 30 min in a humid hydrogen atmosphere, with a hydrogen dew point of -10 °C and a flow rate of 15 m / min; then it is reduced at 850 °C for 60 min in a dry hydrogen atmosphere, with a hydrogen dew point of -60 °C and a flow rate of 40 m / min. The reduced intermediate powder is treated by plasma spheroidization, and spherical tungsten powder for 3D printing with a size of 5 - 25 μm is obtained after classification. The plasma spheroidization process is as follows: powder feeding rate 37.5 g / min, power 40 KW, side gas 1 (argon) 52 slpm, central gas (argon) 19.5 slpm, side gas 2 (hydrogen) 10 slpm, carrier gas (argon) 4.5 slpm, pressure 15 psi. The morphology and properties of the spherical tungsten powder for 3D printing with a size of 5 - 25 μm are as Figure 4 shown in Table 4.

[0043] Table 4 Properties of Spherical Tungsten Powder for 3D Printing with a Size of 5 - 25 μm Prepared without the Addition of Tungsten Trioxide

[0044] Powder composition <![CDATA[Density (g / cm 3 )]]> <![CDATA[Bulk density (g / cm 3 )]]> Flowability (s / 50g) Oxygen content Particle size distribution W 17.34 7.42 14.8 0.0461% <![CDATA[D 10 = 9.2 µm D 50 = 18.7 µm D 90 = 29.3 µm]]>

[0045] Compared with Example 1, in Comparative Example 1, spherical tungsten powder for 3D printing is prepared without adding tungsten trioxide. The strength of the intermediate powder agglomerates obtained during the reduction and sintering process is low, and it cannot maintain the agglomerate morphology during the plasma spheroidization process and breaks into fine W particles, and then bonds into irregular W clusters during the spheroidization process, seriously damaging the use performance of the powder.

[0046] Comparative Example 2: Preparation of spherical tungsten powder for 3D printing with a size of 5 - 25 μm without wet hydrogen reduction-assisted sintering.

[0047] According to the mass ratio of tungsten to tungsten trioxide being 4:1, 2 kg of W powder with an average particle size of 0.5 μm and 0.5 kg of tungsten trioxide with an average particle size of 0.02 μm are ball-milled and mixed with 37.5 g of polyethylene glycol and 1071 g of absolute ethanol to prepare a stable slurry with a solid content of 70%. Spray drying granulation is carried out through a centrifugal spray drying device to obtain a precursor powder. The spray drying process is as follows: the inlet air temperature is 180 °C, and the atomizer rotation speed is 18,000 rpm. In a multi-temperature zone tubular reduction furnace equipment, the precursor powder is reduced by a dry hydrogen isothermal reduction process. The reduction process is as follows: under a dry hydrogen atmosphere, it is reduced at 850 °C for 90 min, the hydrogen dew point is -60 °C, and the flow rate is 40 m / min. The reduced intermediate powder is processed by plasma spheroidization, and spherical tungsten powder for 3D printing with a size of 5 - 25 μm is obtained after classification. The plasma spheroidization process is as follows: the powder feeding rate is 37.5 g / min, the power is 40 KW, the side gas 1 (argon) is 52 slpm, the central gas (argon) is 19.5 slpm, the side gas 2 (hydrogen) is 10 slpm, the carrier gas (argon) is 4.5 slpm, and the pressure is 15 psi. The morphology and properties of the spherical tungsten powder for 3D printing with a size of 5 - 25 μm are shown in Figure 5 and Table 5.

[0048] Table 5 Spherical tungsten powder for 3D printing with a size of 5 - 25 μm prepared without wet hydrogen reduction-assisted sintering

[0049] Powder composition <![CDATA[Density (g / cm 3 )]]> <![CDATA[Bulk density (g / cm 3 )]]> Flowability (s / 50g) Oxygen content Particle size distribution W 16.91 7.12 15.3 0.0857% <![CDATA[D 10 = 8.2 µm D 50 = 16.9 µm D 90 = 24.6 µm]]>

[0050] Compared with Example 1, in Comparative Example 2, the precursor powder obtained by spray drying with dry hydrogen isothermal reduction is used. The volatilization and deposition effect of tungsten trioxide in the dry hydrogen atmosphere is not significant. The cohesive strength of the agglomerates in the reduced intermediate powder is broken into fine W particles during the plasma spheroidization process, and then the fine W particles are bonded into irregular clusters during the spheroidization process, seriously damaging the use performance of the powder.

[0051] The above has described the preferred embodiments of this patent in detail. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of this patent.

Claims

1. A preparation method of spherical tungsten alloy powder for 3D printing, characterized in that: It includes the following steps: Step 1: According to the composition design ratio of the tungsten alloy, ball-mill and mix a tungsten source powder composed of fine-grained tungsten powder and tungsten oxide powder, elemental alloy powder, a solvent, and a binder to prepare a stable slurry with a solid content of 50% to 85%. Spray-dry and spheroidize granulate the slurry through a centrifugal spray-drying device to obtain a precursor powder; wherein, the mass ratio of tungsten powder to tungsten oxide is 4:1 to 10:1; Step 2: Use a multi-temperature-zone tubular reduction furnace equipment to perform wet hydrogen reduction-assisted sintering treatment on the spherical granulated powder obtained in Step 1; adopt wet hydrogen-dry hydrogen isothermal reduction, with a reduction temperature of 750 to 880 °C, or adopt stepwise temperature-rising wet hydrogen reduction, with the first-stage reduction temperature of 700 to 860 °C and the second-stage reduction temperature of 890 to 1100 °C; Step 3: Perform plasma spheroidization treatment on the reduced intermediate powder, and after classification, obtain tungsten alloy powder suitable for 3D printing.

2. The preparation method of a spherical tungsten alloy powder for 3D printing according to claim 1, characterized in that: In Step 1, the average particle size of the fine-grained tungsten powder is 0.1 to 5 μm, and the tungsten oxide powder is selected from one of yellow tungsten, purple tungsten, and blue tungsten, with an average particle size of 0.02 to 2 μm.

3. The preparation method of spherical tungsten alloy powder for 3D printing according to claim 1, wherein: In Step 1, the alloy element is one or more of transition metal elements, and the average particle size of the elemental alloy powder is 0.2 to 10 μm.

4. The preparation method of a spherical tungsten alloy powder for 3D printing according to claim 1, characterized in that: In Step 1, the ball-milling and mixing also includes a dispersant.

5. The preparation method of a spherical tungsten alloy powder for 3D printing according to claim 1, characterized in that: In Step 2, adopt wet hydrogen-dry hydrogen isothermal reduction: The reduction process is divided into 2 stages, and humidified hydrogen and dry hydrogen are respectively introduced. The reduction temperature is 750 to 880 °C, wherein the dew point of hydrogen in the first stage is -15 to 20 °C, the flow rate is 10 to 25 m / min, and the reduction time is 20 to 40 min; the dew point of hydrogen in the second stage is ≤ -50 °C, the flow rate is 30 to 50 m / min, and the reduction time is 30 to 80 min.

6. The preparation method of a spherical tungsten alloy powder for 3D printing according to claim 1, characterized in that: In Step 2, adopt stepwise temperature-rising wet hydrogen reduction: The reduction process adopts stepwise temperature-rising, and humidified hydrogen is introduced in both stages. The first-stage reduction temperature is 700 to 860 °C, the reaction time is 20 to 50 min, the second-stage reduction temperature is 890 to 1100 °C, and the reaction time is 30 to 70 min; the dew point of hydrogen is -40 to -10 °C, and the hydrogen flow rate is 30 to 55 m / min.

7. A preparation method of spherical molybdenum alloy powder for 3D printing, characterized in that: Adopt the preparation method described in any one of claims 1-5, and replace the tungsten source powder with a molybdenum source powder, and the molybdenum source powder adopts fine-grained molybdenum powder and molybdenum oxide powder.

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