A method for additive manufacturing of complex structures of high-density tungsten alloys

Abstract

The application relates to a high-specific-gravity tungsten alloy complex structure additive manufacturing method. The additive manufacturing method comprises the following steps: high-specific-gravity tungsten alloy powder is laid in a powder tray to obtain a powder bed; a water-based binder is sprayed on the powder bed layer by layer according to a forming model to obtain a forming blank; the forming blank is subjected to hot air drying; the forming blank in a vacuum environment is subjected to first heating until the surface temperature of the forming blank is kept at 150 DEG C to 200 DEG C; the forming blank in the vacuum environment is subjected to second heating until the surface temperature of the forming blank is kept at 400 DEG C to 600 DEG C; the forming blank in a hydrogen environment is subjected to third heating until the surface temperature of the forming blank is kept at 1450 DEG C to 1510 DEG C to obtain a high-specific-gravity tungsten alloy complex structure; and the high-specific-gravity tungsten alloy complex structure is cooled to room temperature. The additive manufacturing method has the advantages of high forming efficiency, low raw material cost, good adaptability to structure and size, excellent performance and precision of the formed part.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to an additive manufacturing method for complex structures made of high-density tungsten alloy. Background Technology

[0002] High-density tungsten alloys are alloys composed mainly of W and trace amounts of Ni, Fe, Cu, Co, Mn, and other elements. They have advantages such as high density, high strength, and good toughness, and are widely used in the defense science and technology industry, such as armor-piercing projectile cores, missile damage units, and radioactive shielding materials.

[0003] High-density tungsten alloy components are typically formed using a combination of powder metallurgy liquid-phase sintering and machining. However, the sintering process requires pre-fabricated molds to press the powder, and the high hardness and strength of tungsten alloys make machining difficult. These characteristics limit the efficiency of this method in forming complex components.

[0004] Additive manufacturing (also known as 3D printing) is a technology based on the principle of discrete / accumulated materials to achieve shaping, characterized by digitalization, intelligence, and flexible manufacturing. Compared to traditional equal-material subtractive manufacturing, additive manufacturing is more adaptable to materials and structures, can achieve near-net-shape forming of designed structures, and eliminates the need for molds during manufacturing. It also simplifies and integrates multiple processes, significantly shortening the development cycle and reducing costs. Based on these advantages, how to utilize additive manufacturing to solve the problem of efficient and high-performance forming of complex high-density tungsten alloy structures has become a focus of attention for researchers both domestically and internationally.

[0005] The article "Densification, microstructure and properties of 90W-7Ni-3Fe fabricated by selective laser melting" proposes a method for directly forming 90W-7Ni-3Fe alloy using selective laser melting technology. The resulting molded parts, obtained by melting and bonding the alloy powder under the action of a high-energy laser, achieve a density of over 99% and a strength of 1121 MPa. However, due to the small laser spot size, the powder melting is uneven in different areas during the manufacturing process, resulting in numerous defects in the internal structure of the molded parts and an elongation of less than 1%.

[0006] The articles "Binder jet printing of tungsten heavy alloy" and "Manufacturing process and mechanical properties of BJ3DP tungsten heavy alloy components" propose a method for preparing high-density tungsten alloys by pre-forming a blank using a technology followed by debinding and sintering. The former uses 91W alloy powder obtained through conventional ball milling as raw material, yielding a tungsten alloy with a density of 17.24 g / cm³. 3 The test bar produced had a hardness of 27.3 HRc, a tensile strength of 770 MPa, and an elongation at break of 8.6%, exhibiting mechanical properties lower than those of the sample prepared by liquid-phase sintering in powder metallurgy. The latter, using plasma-densified 93W alloy powder as raw material, yielded a sample with a density higher than 17.8 g / cm³. 3 The test bar has a tensile strength greater than 950 MPa and an elongation at break greater than 20%. Its mechanical properties are comparable to those of the sample prepared by liquid phase sintering in powder metallurgy, but the powder preparation cost is high.

[0007] In summary, current additive manufacturing of high-density tungsten alloy parts still faces challenges such as low mechanical properties, high cost, and complex processes. Summary of the Invention

[0008] Therefore, it is necessary to provide an additive manufacturing method for complex high-density tungsten alloy structures that combines low processing cost, good density and mechanical properties, and high forming accuracy.

[0009] An additive manufacturing method for complex high-density tungsten alloy structures includes the following steps:

[0010] Obtain a forming model of a complex structure of high-density tungsten alloy;

[0011] High-density tungsten alloy powder is spread in a powder tray to obtain a powder bed; the tungsten content in the high-density tungsten alloy powder is 85% to 98% by mass.

[0012] According to the molding model, water-based adhesive is sprayed layer by layer onto the powder bed to obtain a molded blank;

[0013] The molded blank is dried using hot air at 140℃~170℃ for a first preset time period;

[0014] The shaped blank is placed in a high-temperature sintering furnace, and the high-temperature sintering furnace is evacuated to make the shaped blank in a vacuum environment.

[0015] The preform is heated for the first time in a vacuum environment until the surface temperature of the preform rises to 150°C to 200°C, and then held at that temperature for a second preset time period.

[0016] The molded blank is heated a second time in a vacuum environment until the surface temperature of the molded blank rises to 400℃~600℃, and then held at that temperature for a third preset time period.

[0017] The high-temperature sintering furnace is filled with hydrogen gas so that the formed green body is in a hydrogen environment;

[0018] The formed blank is heated for the third time in a hydrogen environment until the surface temperature of the formed blank rises to 1450℃~1510℃ and is held for a fourth preset time period to obtain a complex structure of high specific gravity tungsten alloy.

[0019] The high-density tungsten alloy complex structure was cooled to room temperature.

[0020] In one embodiment, the high-density tungsten alloy powder has a particle size of 2 μm to 20 μm; d 10 The powder particle size is 2μm~4μm, d 50 The powder particle size is 7μm~10μm, d 90 The powder particle size is 17μm to 20μm; the loose packing density of the high-density tungsten alloy powder is 7.5g / cm³. 3 ~9.5g / cm 3 The Hall flow rate (50g) was 25s to 30s.

[0021] In one embodiment, the water-based adhesive has a viscosity of 9 cP to 15 cP, a surface tension of 28 mN / m to 35 mN / m, and a carbon residue fraction of less than 1% after pyrolysis at 1000°C.

[0022] In one embodiment, when spraying water-based adhesive layer by layer, the printing layer thickness is 30μm to 60μm, and the printing speed is 9 seconds / layer to 13 seconds / layer.

[0023] In one embodiment, the first preset time period is 1 hour to 2 hours.

[0024] In one embodiment, the second preset time period is 1h±15min, and the third and fourth preset time periods are both 2h±30min.

[0025] In one embodiment, the temperature rise rate during the first heating is 5±1℃ / min, and the temperature rise rate during the second heating is 3±1℃ / min.

[0026] In one embodiment, the temperature rise rate during the third heating is 10 ± 2 °C / min.

[0027] In one embodiment, the step of cooling the high-density tungsten alloy complex structure to room temperature is: cooling the high-density tungsten alloy complex structure in the furnace and then removing it.

[0028] In one embodiment, before placing the shaped blank into a high-temperature sintering furnace, the step further includes cleaning the dried shaped blank to remove residual powder from its surface.

[0029] The additive manufacturing method for complex high-density tungsten alloy structures described above can form complex structures that are difficult to machine, such as those with internal grooves, non-circular cross-sections, and variable wall thicknesses, with a forming accuracy of up to 0.1 mm. Compared with the traditional method of preparing high-density tungsten alloy parts by powder metallurgy liquid phase sintering + machining, the additive manufacturing method for complex high-density tungsten alloy structures described above has better adaptability to structures and lower cost.

[0030] The high-density tungsten alloy complex structures obtained through the above-described additive manufacturing method are further enhanced by hot air drying, vacuum drying, vacuum degreasing, and high-temperature sintering of the formed blanks. This results in a density of no less than 99%, a tensile strength of 900 MPa–1000 MPa, an elongation of 15%–24%, and a forming accuracy of less than 0.1 mm. Therefore, compared with traditional additive manufacturing technologies for high-density tungsten alloys such as selective laser melting and microdroplet jetting, the high-density tungsten alloy complex structures obtained using this additive manufacturing method exhibit better density and mechanical properties, meeting the mechanical requirements of powder metallurgy liquid-phase sintered parts.

[0031] Therefore, the above-mentioned additive manufacturing method for complex high-density tungsten alloy structures has the advantages of high forming efficiency, low raw material cost, good adaptability to structure and size, and excellent performance and precision of formed parts. It can be used for forming complex high-density tungsten alloy structures in the national defense science and technology industry. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a schematic flowchart of an additive manufacturing method for complex high-density tungsten alloy structures in a preferred embodiment of the present invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0035] 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 to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] When describing positional relationships, unless otherwise specified, when an element is referred to as being "on" another element, it may be directly on the other element or there may be intermediate elements. It is also understood that when an element is referred to as being "between" two elements, it may be the only one between the two elements, or there may be one or more intermediate elements.

[0037] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0038] Please see Figure 1 The preferred embodiment of the present invention is an additive manufacturing method for high-density tungsten alloy complex structures, used for forming high-density tungsten alloy complex structures, including steps S100 to S1001.

[0039] Step S100: Obtain a molding model of a complex high-density tungsten alloy structure.

[0040] The forming model is a three-dimensional model established based on the complex structure of the high-density tungsten alloy to be formed, in order to facilitate subsequent additive manufacturing work.

[0041] In step S200, high-density tungsten alloy powder is placed in a powder tray to obtain a powder bed. The tungsten content in the high-density tungsten alloy powder is 85%–98% by mass.

[0042] Specifically, high-density tungsten alloy powder is evenly spread in the powder tray of a 3DP printing device to obtain a powder bed.

[0043] Specifically, before step S200, the process further includes: mixing tungsten powder, iron powder, and nickel powder by mechanical mixing to obtain high-density tungsten alloy powder. More specifically, the tungsten powder, iron powder, and nickel powder are mixed by high-energy ball milling. High-density tungsten alloy mainly includes tungsten, nickel, and iron.

[0044] Step S300: The water-based adhesive is sprayed layer by layer onto the powder bed according to the molding model to obtain the molded blank.

[0045] Specifically, step S300 includes the following steps: setting printing parameters and printing trajectory according to the molding model; spraying water-based adhesive layer-by-layer agent onto the powder bed according to the printing parameters and printing trajectory to obtain a molded blank.

[0046] Step S400: Dry the preform using hot air at 140℃~170℃ for a first preset time period.

[0047] Specifically, the molded preform is transferred to a forced-air drying oven at 140°C to 170°C for a first preset time period. More specifically, the powder tray along with the molded preform on it is transferred to a forced-air drying oven at 140°C to 170°C for a first preset time period. The first preset time period can be set according to the structure and size of the molded preform.

[0048] Specifically, the preform is dried with hot air at 140℃~170℃ for 1h~2h.

[0049] In step S500, the shaped blank is placed in a high-temperature sintering furnace, and a vacuum treatment is performed inside the furnace to place the shaped blank in a vacuum environment. This ensures that the shaped blank is in a vacuum environment with extremely low oxygen content during steps S600 and S700, reducing the impact of oxygen in the air on the drying and degreasing treatment of the shaped blank.

[0050] Step S600 involves heating the preform in a vacuum environment for the first time until its surface temperature reaches 150°C to 200°C, then holding it at that temperature for a second preset time period. By executing step S600, the preform in the vacuum environment is dried, ensuring the drying effect while reducing costs.

[0051] Specifically, the preform in a vacuum environment is heated for the first time until the surface temperature of the preform reaches 150℃~200℃ and is held for 1h±15min.

[0052] Step S700: The preform in the vacuum environment is heated a second time until the surface temperature of the preform rises to 400℃~600℃ and is then kept at that temperature for a third preset time period.

[0053] In step S700, when the surface temperature of the molded preform rises to 400℃~600℃, the water-based adhesive in the preform decomposes, thus degreasing the preform. The decomposition temperature of the water-based adhesive is usually related to its type; different water-based adhesives have different decomposition temperatures. Therefore, in step S700, the surface temperature of the preform can be raised to different temperatures within the range of 400℃~600℃ depending on the type of water-based adhesive. By executing step S700, the preform can be degreased.

[0054] Specifically, the preform in a vacuum environment is heated a second time until the surface temperature of the preform reaches the decomposition temperature of the water-based adhesive, and then held at that temperature for 2 hours ± 30 minutes.

[0055] In step S800, hydrogen is introduced into the high-temperature sintering furnace to ensure that the formed blank is in a hydrogen environment. This ensures that the formed body remains in a hydrogen environment during step S900. As an inert gas, hydrogen further reduces the oxygen content in the high-temperature sintering environment, thereby reducing the impact of oxygen on the high-temperature sintering process.

[0056] In step S900, the formed blank in the hydrogen environment is heated for the third time until the surface temperature of the formed blank rises to 1450℃~1510℃, and then held at that temperature for a fourth preset time period to obtain a complex structure of high-density tungsten alloy. Thus, by executing step S900, the formed blank is sintered.

[0057] Specifically, the formed blank in a hydrogen environment is heated a third time until the surface temperature of the formed blank reaches 1450℃~1510℃, and then held at that temperature for 2h±30min to obtain a complex structure of high-density tungsten alloy.

[0058] Step S1001: Cool the high-density tungsten alloy complex structure to room temperature.

[0059] By performing steps S100 to S300, a preform with the same or similar shape and size as the complex structure of the high-density tungsten alloy can be obtained. After post-processing the preform with steps S400 to S1001, the complex structure of the high-density tungsten alloy can be obtained. Therefore, by performing steps S100 to S1001, complex structures that are difficult to machine, such as those with internal grooves, non-circular cross-sections, and variable wall thicknesses, can be formed. Compared with the traditional method of preparing high-density tungsten alloy parts by powder metallurgy liquid-phase sintering followed by machining, the above-mentioned additive manufacturing method for complex high-density tungsten alloy structures has better adaptability to structures and lower costs.

[0060] By performing steps S400 to S1001, the formed blank can be subjected to hot air drying, vacuum drying, vacuum degreasing, and high-temperature sintering in a hydrogen environment, thereby obtaining a high-density tungsten alloy complex structure with high density, high tensile strength, and high elongation.

[0061] To gain a more intuitive understanding of the performance of the high-density tungsten alloy complex structures prepared by the above-mentioned additive manufacturing method, the performance test results of several embodiments are listed below.

[0062] In Example 1, the high-density tungsten alloy powder in steps S200 and S300 is 90W-7.1Ni-2.9Fe alloy powder; step S400 is to dry the formed blank with hot air at 170°C for 2 hours; step S900 is to heat the formed blank in a hydrogen environment for the third time until the surface temperature of the formed blank rises to 1450°C and then hold it at that temperature for a fourth preset time period.

[0063] In Example 2, the high-density tungsten alloy powder in steps S200 and S300 is 93W-4Ni-3Fe alloy powder; step S900 is to heat the formed blank in a hydrogen environment for the third time until the surface temperature of the formed blank rises to 1480°C and then hold it for a fourth preset time period.

[0064] In Example 3, the high-density tungsten alloy powder in steps S200 and S300 is 95W-3Ni-2Fe alloy powder; step S900 is to heat the formed blank in a hydrogen environment for the third time until the surface temperature of the formed blank rises to 1510°C and then hold it for a fourth preset time period.

[0065] The tensile properties of Examples 1-3 were tested according to the requirements of GB / T 228.1, and the dimensional accuracy of Examples 1-3 was measured using a height gauge. All test results are shown in Table 1.

[0066] Table 1 Performance test results of Examples 1-3

[0067]

[0068] Practical testing has proven that the high-density tungsten alloy complex structures obtained using the above-mentioned additive manufacturing method exhibit a density of no less than 99%, a tensile strength of 900 MPa to 1000 MPa, an elongation of 15% to 24%, and a forming accuracy of less than 0.1 mm. Therefore, compared with traditional additive manufacturing technologies for high-density tungsten alloys such as selective laser melting and microdroplet jetting, the high-density tungsten alloy complex structures obtained using the above-mentioned additive manufacturing method have better density and mechanical properties, meeting the mechanical requirements of powder metallurgy liquid-phase sintered parts.

[0069] Therefore, the above-mentioned additive manufacturing method for complex high-density tungsten alloy structures is simple to operate, has high forming efficiency, low raw material cost, good adaptability to structure and size, and produces parts with excellent performance and precision. It can be used for forming complex high-density tungsten alloy structures in the national defense science and technology industry.

[0070] In some embodiments, the particle size of the high-density tungsten alloy powder is 2 μm to 20 μm; d 10 The powder particle size is 2μm~4μm, d 50 The powder particle size is 7μm~10μm, d 90 The powder particle size is 17μm to 20μm; the loose packing density of the high-density tungsten alloy powder is 7.5g / cm³. 3 ~9.5g / cm 3 The Hall flow rate (50g) was 25s to 30s.

[0071] It should be noted that d 10 This refers to the particle size distribution that corresponds to a cumulative percentage (including all preceding and following particle sizes) of 10% for a given sample; d 50 This refers to the particle size corresponding to a cumulative particle size distribution percentage of 50% for a sample; d 90 This refers to the particle size corresponding to a sample when the cumulative particle size distribution number reaches 90%.

[0072] If the powder is too fine during steps S100 to S300, its flowability will be poor, which may lead to uneven powder spreading and peeling after spraying the adhesive, affecting molding efficiency and precision. If the powder is too coarse during steps S400 to S1001, its sintering activity will be low, resulting in poor density and mechanical properties of the prepared components.

[0073] Based on this, in steps S200 and S300, high-density tungsten alloy powder with a particle size between 2μm and 20μm is selected. Particles with a particle size ≤2μm to 4μm account for only 10% of all high-density tungsten alloy powders, particles with a median diameter or median particle size ≤7μm to 10μm account for 50% of all high-density tungsten alloy powders, and particles with a particle size ≤17μm to 20μm account for 90% of all high-density tungsten alloy powders. Therefore, the high-density tungsten alloy powder has a small and uniform particle size, which makes it easier to form when performing steps S100 to S300, which is beneficial to improving the forming efficiency and forming accuracy. At the same time, it can also ensure that the density of the complex structure of the prepared high-density tungsten alloy is not less than 99%, the tensile strength reaches 900MPa to 1000MPa, the elongation is 15% to 24%, and the forming accuracy is less than 0.1mm.

[0074] In some embodiments, the water-based adhesive has a viscosity of 9 cP to 15 cP, a surface tension of 28 mN / m to 35 mN / m, and a carbon residue fraction of less than 1% after pyrolysis at 1000°C.

[0075] In this invention, high-density tungsten alloy powder needs to be bonded and formed using an adhesive. However, if the viscosity and surface tension of the adhesive are too high, the wetting effect on the powder will be poor, which will easily lead to peeling of the powder surface and loose bonding of the underlying powder, resulting in poor strength and dimensional accuracy of the blank. On the other hand, if the viscosity and surface tension of the adhesive are too low, the bonding effect on the underlying powder will be weak, and it will easily penetrate to the lower layer of the powder bed, resulting in difficulty in powder spreading and poor strength and dimensional accuracy of the blank. Moreover, the amount of residual carbon from the cracking of the adhesive is related to the density and impurity content of the blank after sintering, which directly affects the mechanical properties of the parts.

[0076] Based on this, in step S300, a water-based binder with a viscosity of 9 cP to 15 cP, a surface tension of 28 mN / m to 35 mN / m, and a carbon residue of less than 1% after pyrolysis at 1000℃ is selected. This ensures that after performing steps S100 to S300, a formed blank with high strength and high dimensional accuracy can be obtained. It also ensures that after performing steps S400 to S1001, a blank with high density and mechanical properties that meet the performance requirements of powder metallurgy liquid phase sintered parts can be obtained, thus ensuring high product quality for complex high-density tungsten alloy structures.

[0077] In some embodiments, when performing step S300, the printing layer thickness is 30μm to 60μm, and the printing speed is 9 seconds / layer to 13 seconds / layer.

[0078] In this invention, the microdroplet jetting process parameters are designed to match the characteristics of the water-based binder. If the printing layer thickness is too thin or the printing speed is too slow, the processing efficiency of complex high-density tungsten alloy structures in the liquid phase will be reduced. Conversely, if the printing layer thickness is too thick or the printing speed is too fast, the water-based binder will not be able to completely wet a single layer of powder. Therefore, in steps S200 and S300, the printing layer thickness is set to 30μm–60μm, and the printing speed is set to 9 seconds / layer–13 seconds / layer. This ensures a relatively high forming speed while maintaining the mechanical properties and product quality of the complex high-density tungsten alloy structure.

[0079] In some embodiments, the temperature rise rate during the first heating is 5 ± 1 °C / min, and the temperature rise rate during the second heating is 3 ± 1 °C / min. Therefore, the temperature rise rates during steps S600 and S700 are very low.

[0080] In this invention, degreasing and sintering are key processes for imparting complex structural properties to high-density tungsten alloys. High performance is predicated on high component density, few impurity phases, and fine grains. In the additive manufacturing method for the aforementioned complex high-density tungsten alloy structures, steps S600 and S700 are performed to dry and degrease the formed blank. Slower temperature rise rates and a vacuum environment within the high-temperature sintering furnace are designed in steps S600 and S700 to ensure complete removal of moisture and organic matter in the low-temperature zone, which is beneficial for improving the performance of complex high-density tungsten alloy structures.

[0081] In some embodiments, the temperature rise rate during the third heating is 10 ± 2 °C / min. Thus, the temperature rise rate is relatively high when performing step S900.

[0082] In the above-mentioned additive manufacturing method for complex high-density tungsten alloy structures, steps S800 and S900 are performed to sinter the formed billet at high temperature in a hydrogen environment. Step S900 incorporates a relatively fast temperature rise rate and a hydrogen environment within the high-temperature sintering furnace. This ensures the high-density tungsten alloy is sintered densely while avoiding strength reduction caused by oxidation reactions and grain coarsening, thus contributing to the improvement of the mechanical properties of complex high-density tungsten alloy structures.

[0083] In some embodiments, step S1001 is: the high-density tungsten alloy complex structure is cooled in the furnace and removed.

[0084] The following method involves naturally cooling the complex high-density tungsten alloy structure to room temperature or near room temperature in a hydrogen atmosphere. This reduces the likelihood of oxidation when the complex structure comes into contact with air at high temperatures, which is beneficial for further improving product quality.

[0085] In some embodiments, before step S500, the method further includes a step of cleaning the dried molded blank to remove residual powder from the surface of the molded blank.

[0086] An additional step is added between steps S400 and S500: cleaning the dried molded blank to remove residual powder from its surface. During step S300, some powder inevitably adheres to the surface of the molded blank. After step S400, this residual powder is cleaned to ensure the cleanliness of the molded blank surface and prevent residual powder from melting and forming on the complex surface of the high-density tungsten alloy structure during subsequent steps S500 to S900.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An additive manufacturing method for complex structures made of high-density tungsten alloy, characterized in that, Including the following steps: Obtain a forming model of a complex structure of high-density tungsten alloy; High-density tungsten alloy powder is spread in a powder tray to obtain a powder bed; the tungsten content in the high-density tungsten alloy powder is 85% to 98% by mass; the particle size of the high-density tungsten alloy powder is 2 μm to 20 μm; d 10 The powder particle size is 2μm~4μm, d 50 The powder particle size is 7μm~10μm, d 90 The powder particle size is 17μm to 20μm; the loose packing density of the high-density tungsten alloy powder is 7.5g / cm³. 3 ~9.5g / cm 3 The Hall flow rate is 25s / 50g to 30s / 50g; According to the molding model, the water-based adhesive is sprayed layer by layer onto the powder bed to obtain a molded blank; the viscosity of the water-based adhesive is 9cP to 15cP, the surface tension is 28 mN / m to 35 mN / m, and the residual carbon fraction after decomposition at 1000℃ is less than 1%; when spraying the water-based adhesive layer by layer, the printing layer thickness is 30μm to 60μm, and the printing speed is 9 seconds / layer to 13 seconds / layer; The molded preform is dried with hot air at 140℃~170℃ for 1h~2h; The shaped blank is placed in a high-temperature sintering furnace, and the high-temperature sintering furnace is evacuated to make the shaped blank in a vacuum environment. The preform under vacuum is heated for the first time at a temperature rise efficiency of 5±1℃ / min until the surface temperature of the preform reaches 150℃~200℃ and is held for 1h±15min. The molded blank is heated a second time in a vacuum environment, with a temperature rise efficiency of 3±1℃ / min until the surface temperature of the molded blank reaches 400℃~600℃, and then held at that temperature for 2h±30min. The high-temperature sintering furnace is filled with hydrogen gas so that the formed green body is in a hydrogen environment; The formed blank in a hydrogen environment is heated for the third time at a temperature rise efficiency of 10±2℃ / min until the surface temperature of the formed blank reaches 1450℃~1510℃ and is held for 2h±30min to obtain a complex structure of high specific gravity tungsten alloy. The high-density tungsten alloy complex structure was cooled to room temperature.

2. The additive manufacturing method according to claim 1, characterized in that, The step of cooling the high-density tungsten alloy complex structure to room temperature is as follows: the high-density tungsten alloy complex structure is cooled in the furnace and then removed.

3. The additive manufacturing method according to claim 1, characterized in that, Before placing the shaped blank into the high-temperature sintering furnace, the process also includes cleaning the dried shaped blank to remove residual powder from its surface.

4. The additive manufacturing method according to claim 1, characterized in that, Before the step of placing the high-density tungsten alloy powder in the powder pan, the process includes the step of mixing tungsten powder, iron powder, and nickel powder by mechanical mixing to obtain the high-density tungsten alloy powder.

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