High-performance and high-density tungsten materials prepared by laser additive manufacturing and their preparation methods

Abstract

The present invention discloses a high-performance and high-specific-gravity tungsten material prepared by laser additive manufacturing and a preparation method thereof. Hexagonal boron nitride is used as a strengthening phase of the metallic tungsten material, and LPBF is adopted to form a high-performance and high-specific-gravity tungsten material with tungsten as the matrix. During the LPBF forming process of the high-performance and high-specific-gravity tungsten material, hexagonal boron nitride promotes the equiaxed grain of the tungsten matrix by virtue of its high melting point characteristic, and decomposes during the forming process of the tungsten material to leave beneficial boron atoms in the tungsten matrix to form solid solution strengthening, thereby forming a high-performance and high-specific-gravity tungsten material with tungsten as the matrix on the substrate. Therefore, the present invention reduces the introduction of impurities modified by the reinforcing phase. In addition, the tungsten material prepared by the present invention forms oxides dispersed in the matrix, has equiaxed grains, and has solid solution strengthening, ensuring the performance of the formed component while ensuring a high tungsten specific gravity.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser powder bed fusion forming of metal components, and particularly relates to a high-performance and high-specific gravity tungsten material prepared by laser additive manufacturing and a preparation method thereof. Background Art

[0002] Tungsten has high density, high-temperature strength, excellent corrosion resistance, radiation resistance and thermal conductivity, and is thus applied in the fields of aerospace, military, nuclear industry, medical treatment, etc. (such as: penetrator cores, shaped charges for armor piercing, fragmentation warheads and collimators, etc.).

[0003] Traditional tungsten material forming processes are all based on the mechanism of liquid phase sintering (LPS), and there are problems such as difficulty in completely melting tungsten powder, long mold manufacturing cycle and high cost, and easy generation of pores inside the formed components, which limit the application of tungsten as a structural material.

[0004] The rapid development of laser additive manufacturing (LAM) technology provides new ideas for the forming of W alloys. Among them, the laser powder bed fusion (LPBF) technology with high flexibility can solve the problems existing in the traditional W material forming methods. The LPBF technology is a LAM technology based on powder spreading, without the use of molds, so it is less restricted by structural complexity; at the same time, the LPBF technology uses a laser spot with a small diameter and concentrated energy, which can completely melt W particles, and has become one of the methods for preparing high-performance tungsten material components.

[0005] Most of the additive manufactured tungsten materials reported in the existing literature are formed by LPBF technology. The main ways to improve the performance of tungsten components formed by LPBF are process optimization and reinforcement phase modification. In view of the limited degree of performance improvement that can be achieved only through process optimization, therefore, the method of reinforcement phase modification has received extensive attention from scholars.

[0006] In recent years, there have been many studies on the reinforcement phase modification of tungsten materials formed by LPBF. The reinforcement phases are mostly ceramic particles or metal particles, such as ZrC, TiC, Y2O3, Co, Ta, Ti, Ni, Fe, etc. It can be seen that when using the reinforcement phase modification method to improve the performance of tungsten material components formed by LPBF, the introduction of a large amount of impurity elements may affect the performance of the tungsten material itself (such as high density, radiation resistance, etc.). Therefore, reducing the introduction of impurities while ensuring a high tungsten specific gravity is crucial for improving the performance of the formed components. Summary of the Invention

[0007] The present invention aims to develop a high-performance and high-specific-gravity tungsten material based on elemental autophagy and its preparation method. Hexagonal boron nitride is used as a strengthening phase for metallic tungsten, and a tungsten material is formed by laser powder bed fusion, promoting the equiaxedization of tungsten material grains. During the forming process, the decomposition of hexagonal boron nitride occurs, the N element leaves the matrix, and after the B atoms are burned and evaporated, some of them leave the matrix, leaving beneficial boron atoms in the tungsten matrix to form solid solution strengthening. While effectively improving the microstructure and properties of W, the content of metallic tungsten in the tungsten material is maintained. Therefore, the present invention can effectively improve the mechanical properties such as strength and ductility of the formed specimen while ensuring a high tungsten specific gravity.

[0008] To achieve the above technical objectives, the present invention will adopt the following technical solutions:

[0009] A high-tungsten-specific-gravity mixed powder for laser powder bed fusion of a high-specific-gravity tungsten material, the high-tungsten-specific-gravity mixed powder comprising tungsten and hexagonal boron nitride, wherein: the mass ratio of hexagonal boron nitride is 0.01% - 0.2%.

[0010] Preferably, the high-tungsten-specific-gravity mixed powder is obtained by mixing raw material powders through a ball milling process; the raw material powders include tungsten powder and hexagonal boron nitride powder, and among the raw material powders, the particle size of the tungsten powder is 5μm - 25μm, and the particle size of the hexagonal boron nitride is 1μm - 2μm.

[0011] Preferably, the grinding balls used in the ball milling process are ceramic grinding balls, and the process parameters of the ball milling process are: the ball-to-material ratio is 1:2, the ball milling time is 6h, and the ball milling speed is 250r / min.

[0012] Another technical objective of the present invention is to provide a preparation method for a laser additive manufacturing high-performance and high-specific-gravity tungsten material, comprising the following steps:

[0013] Step (1), preparing a high-tungsten-specific-gravity mixed powder:

[0014] Placing the raw material powders in a ceramic ball milling tank according to a certain ratio, and mixing the raw material powders through a ball milling process to obtain a high-tungsten-specific-gravity mixed powder, wherein: the raw material powders include tungsten powder and hexagonal boron nitride powder, and the mass ratio of hexagonal boron nitride is 0.01% - 0.2%;

[0015] Step (2), laser powder bed fusion forming:

[0016] Performing laser powder bed fusion forming on the high-tungsten-specific-gravity mixed powder obtained in step (1), with the laser power used being 160W - 200W, the scanning speed being 150mm / s - 250mm / s, the scanning spacing being 30μm - 150μm, and the layer thickness being 20μm;

[0017] During the laser powder bed fusion forming process of the high-tungsten specific gravity mixed powder, hexagonal boron nitride decomposes, prompting nitrogen atoms to form nitrogen gas and leave the tungsten matrix, and etching some boron atoms to leave beneficial boron atoms in the tungsten matrix to form solid solution strengthening, thereby forming a high-performance high-specific gravity tungsten material with tungsten as the matrix on the substrate.

[0018] Preferably, in step (1), the particle size of the tungsten powder in the raw material powder is 5 - 25 μm, and the particle size of the hexagonal boron nitride is 1 - 2 μm.

[0019] Preferably, in step (1), the grinding balls used in the ball milling process are ceramic grinding balls, the ball-to-material ratio is 1:2, the ball milling time is 6 h, and the ball milling speed is 250 r / min.

[0020] Preferably, in step (1), the mass ratio of the hexagonal boron nitride included in the raw material powder is 0.1%.

[0021] In step (2), the laser power used is 180 W, and the scanning speed is 200 mm / s.

[0022] Preferably, in step (2), during the laser powder bed fusion forming process of the high-tungsten specific gravity mixed powder, high-purity argon is used as the protective atmosphere throughout the process.

[0023] Preferably, in step (2), before the high-tungsten specific gravity mixed powder is spread on the substrate, a substrate preheating mode is adopted to reduce stress, thereby improving the forming density and performance.

[0024] Another technical object of the present invention is to provide a laser additive manufacturing high-performance high-specific gravity tungsten material, which is made by the above-mentioned preparation method of the laser additive manufacturing high-performance high-specific gravity tungsten material. The high-performance high-specific gravity tungsten material has equiaxed grains, and in the high-performance high-specific gravity tungsten material, there are oxides dispersed in the tungsten matrix and solid solution strengthening exists.

[0025] Based on the above technical solutions, compared with the prior art, the advantages of the present invention are:

[0026] 1. Hexagonal boron nitride has a relatively high melting point (about 3300 K) and hardness (Mohs hardness about 9.5). The relatively high melting point of hexagonal boron nitride ensures its structural stability at high temperatures, while the high hardness indicates its potential to improve the required properties of materials such as strength, hardness, and wear resistance. At the same time, the melting point / decomposition point of hexagonal boron nitride is lower than that of tungsten (3422 °C). Therefore, in the present invention, hexagonal boron nitride is used as the strengthening phase of the metallic tungsten material, and LPBF is used to form a high-performance high-density tungsten material with tungsten as the matrix. During the LPBF forming process of this high-performance high-density tungsten material, hexagonal boron nitride promotes the equiaxedization of tungsten matrix grains by virtue of its high melting point characteristics, and decomposes during the tungsten material forming process, causing nitrogen atoms to form nitrogen gas and leave the tungsten matrix, while etching part of the boron atoms, so as to leave beneficial boron atoms in the tungsten matrix to form solid solution strengthening, thereby forming a high-performance high-density tungsten material with tungsten as the matrix on the substrate. Therefore, the present invention reduces the introduction of impurities modified by this reinforcing phase. In addition, the tungsten material prepared in the present invention forms oxides dispersed in the matrix, has equiaxed grains, and there is solid solution strengthening, thus significantly improving the strength and ductility of the tungsten material, and thus improving the performance of the formed component on the premise of ensuring a high tungsten density.

[0027] 2. For the high-performance high-density tungsten material mentioned in the present invention, the optimal content of hexagonal boron nitride is very low (only 0.1% by mass), and hexagonal boron nitride can be decomposed under the action of laser. Compared with pure tungsten formed by laser powder bed melting under the same conditions, the mass fraction of tungsten element in the high-performance high-density tungsten material obtained under optimized process and content is the same (99.96%), effectively ensuring the high tungsten density characteristics of this high-performance tungsten material.

[0028] The high-performance high-density tungsten material prepared in the present invention is applicable to the field of high-performance tungsten-based structural materials, especially applicable to armor-piercing projectiles and armor-piercing fragmentation projectiles, and is also applicable to materials such as radiation shielding covers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a process flow chart of a preparation method for a high-performance high-density tungsten-based composite material.

[0030] Figure 2 It is the grain boundary distribution of 0.01 wt.% hexagonal boron nitride / tungsten high-performance high-density tungsten-based composite material in Example 1.

[0031] Figure 3 It is the grain boundary distribution of 0.1 wt.% hexagonal boron nitride / tungsten high-performance high-density tungsten-based composite material in Example 14.

[0032] Figure 4 It is the oxides dispersed in the 0.1 wt.% hexagonal boron nitride / tungsten high-performance high-density tungsten-based composite material in Example 14.

[0033] Figure 5 The grain boundary distribution of 0.1 wt.% hexagonal boron nitride / tungsten high-performance high-specific gravity tungsten-based composite material in Example 15.

[0034] Figure 6 The grain boundary distribution of 0.1 wt.% hexagonal boron nitride / tungsten high-performance high-specific gravity tungsten-based composite material in Example 16.

[0035] Figure 7 The grain boundary distribution of 0.2 wt.% hexagonal boron nitride / tungsten high-performance high-specific gravity tungsten-based composite material in Example 27.

[0036] Figure 8 The grain boundary distribution of 0.5 wt.% hexagonal boron nitride / tungsten high-performance high-specific gravity tungsten-based composite material in Example 40.

[0037] Figure 9 The grain boundary distribution of pure tungsten material in Comparative Example 1.

[0038] Figure 10 The TEM image of pure tungsten material in Comparative Example 1. Detailed implementation manners

[0039] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification and embodiments, but the protection scope of the present invention is not limited thereto. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention.

[0040] To illustrate in detail the technical solutions involved in the present invention, the present invention provides a total of 52 examples and 13 comparative examples (refer to Table 1 below). By adding a specific amount (mass ratio of 0.01%-0.2%) of hexagonal boron nitride to pure tungsten powder and subjecting it to ball milling process treatment, a high-tungsten specific gravity mixed powder can be prepared; then, by using specific laser powder bed fusion process parameters for forming, a high-performance high-specific gravity tungsten-based material with tungsten as the matrix can be obtained; the laser powder bed fusion process parameters used are: laser power is 160W-200W, scanning speed is 150mm / s-250mm / s, scanning spacing is 30μm-150μm, and layer thickness is 20μm. During the laser powder bed fusion forming process of the high-tungsten specific gravity mixed powder, hexagonal boron nitride decomposes, promoting nitrogen atoms to form nitrogen gas and leave the tungsten matrix, and burning and evaporating part of the boron atoms to leave beneficial boron atoms in the tungsten matrix to form solid solution strengthening, thereby forming a high-performance high-specific gravity tungsten-based material with tungsten as the matrix on the substrate.

[0041] Table 1

[0042]

[0043]

[0044]

[0045] The technical solutions involved in the present invention will be described in detail below in combination with each embodiment and comparative example.

[0046] Example 1

[0047] This example is a high-performance high-specific gravity tungsten material and its preparation method.

[0048] The composite material involved has a composition of 0.01 wt.% hexagonal boron nitride / tungsten. The tungsten powder involved has a particle size of 5 - 25 μm, and the hexagonal boron nitride has a particle size of 1 - 2 μm.

[0049] The preparation method of this example specifically includes the following steps, and the process can be referred to Figure 1 :

[0050] Step (1), prepare a high-tungsten specific gravity mixed powder:

[0051] Place tungsten powder and hexagonal boron nitride powder in a ceramic ball mill tank according to the designed ratio for ball milling and mixing. The grinding balls used are ceramic grinding balls, and the ball-to-material ratio is 1:2. Fill high-purity argon gas in the ball mill tank as a protective atmosphere. The ball milling time is 6 h, and the rotation speed is 250 r / min to obtain a high-tungsten specific gravity mixed powder;

[0052] Step (2), laser powder bed fusion forming:

[0053] Use the obtained mixed powder for laser powder bed fusion forming. The laser power used is 180 W, the scanning speed is 200 mm / s, the scanning spacing is 120 μm, and the layer thickness is 20 μm. The whole forming process uses high-purity argon gas as a protective atmosphere. After laser forming and cooling, use electrical discharge machining to separate the specimen from the substrate to obtain the 0.01 wt.% hexagonal boron nitride / tungsten high-performance high-specific gravity tungsten-based composite material. The grain boundary distribution of the obtained composite material is as Figure 2 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend, the average grain size is 28.38 μm, the room temperature compressive strength is 1210.07 MPa, and the elongation is 12.23%.

[0054] For Examples 4 - 52 and Comparative Examples 1 - 13, the operation steps of Example 1 can be referred to. Prepare a high-tungsten specific gravity mixed powder according to the mass ratio of hexagonal boron nitride recorded in Table 1, and form the prepared high-tungsten specific gravity mixed powder according to the corresponding laser powder bed fusion forming process parameters (laser power, scanning speed, and scanning spacing) to obtain the corresponding high-performance high-specific gravity tungsten-based composite material. The room temperature compressive strength and elongation of the obtained composite material are shown in Table 1.

[0055] The following elaborates in more detail on some of the examples and comparative examples recorded in Table 1.

[0056] Example 2

[0057] Refer to the implementation steps of Example 1. The difference between this example and Example 1 is only that the scanning speed used in laser powder bed fusion forming in step (2) is changed. In this example, the scanning speed is 150 mm / s. The room-temperature compressive strength of the finally obtained composite material is 1180.90 MPa, and the elongation is 12.05%.

[0058] Example 3

[0059] The difference between this example and Example 1 is only that the scanning speed used in laser powder bed fusion forming in step (2) is changed. In this example, the scanning speed is 250 mm / s. The room-temperature compressive strength of the finally obtained composite material is 1199.30 MPa, and the elongation is 11.97%.

[0060] Example 14

[0061] The difference between this example and Example 1 is only that the amount of hexagonal boron nitride added when preparing the high-tungsten specific gravity mixed powder in step (1) is changed. In this example, the mass ratio of hexagonal boron nitride is 0.1%. The finally obtained grain boundary distribution is as Figure 3 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend, the average grain size is 16.60 μm, the room-temperature compressive strength is 1533.59 MPa, and the elongation is 17.46%. The TEM image of the specimen is as Figure 4 shown. It can be seen that dispersed oxide particles are formed inside the formed specimen. The inductively coupled plasma (ICP) and oxygen-nitrogen-hydrogen analyzer (ONH) of the specimen are shown in Table 2 (mass fraction). It can be seen that the tungsten mass fraction is 99.96%.

[0062] Table 2

[0063] W B N O powder 99.87 0.04 0.06 0.03 formed block 99.96 0.02 0.00 0.02

[0064] Example 15

[0065] The difference between this example and Example 6 is only that the amount of hexagonal boron nitride added when preparing the high-tungsten specific gravity mixed powder in step (1) is changed. In this example, the mass ratio of hexagonal boron nitride is 0.1%. The finally obtained grain boundary distribution of the composite material is as Figure 5 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend, the average grain size is 17.34 μm, the room-temperature compressive strength is 1421.36 MPa, and the elongation is 16.39%.

[0066] Example 16

[0067] The difference between this embodiment and Embodiment 8 lies only in changing the dosage of hexagonal boron nitride added when preparing the high-tungsten specific gravity mixed powder in step (1). In this embodiment, the mass ratio of hexagonal boron nitride is 0.1%. The grain boundary distribution of the finally prepared composite material is as follows Figure 6 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend. The average grain size is 32.11 μm, the room-temperature compressive strength is 1332.54 MPa, and the elongation is 13.11%.

[0068] Embodiment 27

[0069] The difference between this embodiment and Embodiment 1 lies only in changing the dosage of hexagonal boron nitride added when preparing the high-tungsten specific gravity mixed powder in step (1). In this embodiment, the mass ratio of hexagonal boron nitride is 0.2%. The grain boundary distribution of the finally prepared composite material is as follows Figure 7 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend. The average grain size is 29.60 μm, the room-temperature compressive strength is 1171.42 MPa, and the elongation is 9.96%.

[0070] Embodiment 40

[0071] The difference between this embodiment and Embodiment 1 lies only in changing the dosage of hexagonal boron nitride added when preparing the high-tungsten specific gravity mixed powder in step (1). In this embodiment, the mass ratio of hexagonal boron nitride is 0.5%. The grain boundary distribution of the finally prepared composite material is as follows Figure 5 shown. It can be seen that the grain morphology of the specimen has an obvious equiaxed trend. The average grain size is 23.83 μm, but there are a large number of pores inside the specimen, which reduces the mechanical properties of the formed specimen. The room-temperature compressive strength of the formed specimen is 322.56 MPa, and the elongation is 5.13%.

[0072] Based on Embodiments 1-13, it can be known that considering comprehensively the room-temperature compressive strength and elongation of the prepared composite material, when the mass ratio of hexagonal boron nitride powder is 0.1%, the relatively excellent laser powder bed fusion forming process parameters are: laser power is 180 W, scanning speed is 200 mm / s, scanning spacing is 120 μm, and layer thickness is 20 μm.

[0073] For the high-performance high-specific gravity tungsten materials (Embodiments 1 to 39) prepared by the present invention, compared with the laser powder bed fusion pure tungsten powder parts (comparative example) without adding hexagonal boron nitride, the performance index of room-temperature compressive strength is effectively improved, and the increase is not less than 20%; and when the mass ratio of hexagonal boron nitride is 0.1%, both the room-temperature compressive strength and elongation performance indexes are greatly improved. Among them: the increase in room-temperature compressive strength is as high as 98%, and the increase in elongation exceeds 125%.

[0074] Comparative Example 1

[0075] Refer to the implementation operation of Example 1. The difference between Comparative Example 1 and Example 1 is only that: the tungsten material involved in Comparative Example 1 does not contain hexagonal boron nitride and is only a pure tungsten material formed by laser powder bed fusion. The grain boundary distribution of the obtained tungsten material is as Figure 9 shown. It can be seen that the grains of the formed specimen are columnar crystals, the average grain size is 40.75 μm, the room temperature compressive strength is 789.15 MPa, and the elongation is 7.75%. The TEM image of the specimen is as Figure 10 shown. It can be seen that no dispersed oxides are formed in the specimen. The quantitative results of inductively coupled plasma (ICP) and oxygen, nitrogen, and hydrogen analyzer (ONH) of the specimen are shown in Table 2 (mass fraction), and the tungsten mass fraction is 99.96%.

[0076] Table 3

[0077] W B N O powder 99.99 0.00 0 0.01 formed block 99.96 0.00 0 0.04

[0078] Based on Examples 1-39, compared with Comparative Examples 1-13, when the added mass ratio of hexagonal boron nitride powder in the high-tungsten specific gravity mixed powder described in the present invention is 0.01%-0.2%, and formed by laser powder bed fusion process parameters (laser power is 160 W-200 W, scanning speed is 150 mm / s-250 mm / s, scanning spacing is 30 μm-150 μm, layer thickness is 20 μm), the obtained high-performance high-specific gravity tungsten composite material has greatly improved room temperature compressive strength and elongation, and improves the forming part performance of pure tungsten powder under the same laser printing forming process conditions. Considering the room temperature compressive strength and elongation of the obtained composite material comprehensively, the relatively excellent laser powder bed fusion forming process parameters are: laser power is 180 W, scanning speed is 200 mm / s, scanning spacing is 120 μm, and layer thickness is 20 μm.

[0079] Except for the above-described detailed examples and comparative examples, the remaining examples and comparative examples in Table 1 can be implemented with reference to the implementation steps of Example 1. And during implementation, only the parameters corresponding to each example / comparative example recorded in Table 1 need to be replaced with the same parameters recorded in Example 1. Therefore, they will not be elaborated one by one here.

[0080] The high-performance high-density tungsten materials prepared in the present invention (Examples 1 to 39), compared with the laser powder bed fusion pure tungsten powder parts without adding hexagonal boron nitride (comparative example), effectively improve the performance index of room temperature compressive strength, and the increase is not less than 20%; and when the mass ratio of hexagonal boron nitride is 0.1%, both the room temperature compressive strength and elongation are greatly improved. Among them: the increase in room temperature compressive strength is as high as 98%, and the increase in elongation exceeds 125%. That is, the performance of the 0.1wt.% hexagonal boron nitride / tungsten composite material formed under the optimized laser process (laser power is 160W - 200W, scanning speed is 150mm / s - 250mm / s, scanning spacing is 30μm - 150μm, layer thickness is 20μm) is the best, which is related to its finest grain size and the most uniform microstructure. Compared with Comparative Example 1, dispersed oxides are formed in the 0.1wt.% hexagonal boron nitride / tungsten composite material formed under the optimized process. The combined action of the formed dispersion strengthening and fine grain strengthening makes the strength and elongation of 0.1wt.% hexagonal boron nitride / tungsten significantly higher than that of pure tungsten. In addition, hexagonal boron nitride decomposes during the forming process, the N element leaves the matrix, and after the B atoms are burned and evaporated, part of them leave the matrix. The remaining beneficial B atoms form solid solution strengthening, which also plays an important role in improving the performance of the specimen.

[0081] Based on Examples 40 - 52, compared with Comparative Documents 1 - 13, when the added mass ratio of hexagonal boron nitride powder in the high-tungsten specific gravity mixed powder described in the present invention is 0.5%, and formed by the laser powder bed fusion process parameters (laser power is 160W - 200W, scanning speed is 150mm / s - 250mm / s, scanning spacing is 30μm - 150μm, layer thickness is 20μm), the performance of the formed specimen is lower than that of pure tungsten, indicating that the excessive addition of hexagonal boron nitride will instead reduce the forming performance of tungsten materials.

Claims

1. A high-tungsten specific gravity mixed powder for use in laser powder bed fusion to form high specific gravity tungsten materials, characterized in that, The high-tungsten specific gravity mixed powder is composed of tungsten and hexagonal boron nitride, wherein: the mass ratio of hexagonal boron nitride is 0.01% - 0.2%.

2. The high-tungsten specific gravity mixed powder according to claim 1, wherein The high-tungsten specific gravity mixed powder is obtained by mixing raw material powders through a ball milling process; the raw material powders include tungsten powder and hexagonal boron nitride powder, and in the raw material powders, the particle size of the tungsten powder is 5 - 25 μm, and the particle size of the hexagonal boron nitride is 1 - 2 μm.

3. The high-tungsten specific gravity mixed powder according to claim 2, wherein The grinding balls used in the ball milling process are ceramic grinding balls, and the process parameters of the ball milling process are: the ball-to-material ratio is 1:2, the ball milling time is 6 h, and the ball milling speed is 250 r / min.

4. A preparation method of a high-performance and high-specific-gravity tungsten material by laser additive manufacturing, characterized in that, It includes the following steps: Step (1), preparing the high-tungsten specific gravity mixed powder: Placing the raw material powders in a ceramic ball milling tank according to a certain ratio, and mixing the raw material powders through a ball milling process to obtain the high-tungsten specific gravity mixed powder, wherein: the raw material powders are composed of tungsten powder and hexagonal boron nitride powder, and the mass ratio of hexagonal boron nitride is 0.01% - 0.2%; Step (2), laser powder bed fusion forming: Performing laser powder bed fusion forming on the high-tungsten specific gravity mixed powder obtained in step (1), with the laser power used being 160 W - 200W, the scanning speed being 150 mm / s - 250 mm / s, the scanning spacing being 30μm - 150 μm, and the layer thickness being 20 μm.

5. The preparation method of the high-performance and high-specific-gravity tungsten material by laser additive manufacturing according to claim 4, wherein, In step (1), the particle size of the tungsten powder in the raw material powders is 5μm - 25μm, and the particle size of the hexagonal boron nitride is 1μm - 2μm.

6. The preparation method of the high-performance and high-specific gravity tungsten material by laser additive manufacturing according to claim 4, wherein, In step (1), the grinding balls used in the ball milling process are ceramic grinding balls, the ball-to-material ratio is 1:2, the ball milling time is 6 h, and the ball milling speed is 250 r / min.

7. The preparation method of the high-performance and high-specific gravity tungsten material by laser additive manufacturing according to claim 4, characterized in that, In step (1), the mass ratio of the hexagonal boron nitride included in the raw material powders is 0.1%.

8. The preparation method of the high-performance and high-specific gravity tungsten material by laser additive manufacturing according to claim 7, wherein, In step (2), the laser power used is 180W, the scanning speed is 200mm / s, and the scanning spacing is 120 μm.

9. The preparation method of the high-performance and high-specific-gravity tungsten material by laser additive manufacturing according to claim 4, wherein, In step (2), during the laser powder bed fusion forming process of the high-tungsten specific gravity mixed powder, high-purity argon is used as the protective atmosphere throughout the process; Before powder spreading of the high-tungsten specific gravity mixed powder on the substrate, a substrate preheating mode is adopted to reduce stress, thereby improving the forming density and performance.

10. A high-performance high-specific gravity tungsten material, characterized in that, It is made by the preparation method of a high-performance high-specific gravity tungsten material by laser additive manufacturing according to any one of claims 4 to 8; the high-performance high-specific gravity tungsten material has equiaxed grains, and in the high-performance high-specific gravity tungsten material, there are oxides dispersed in the tungsten matrix and solid solution strengthening exists.

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