Bimodal particle size distribution titanium-based powder for low cost additive manufacturing, titanium-based articles and methods of making the same

Abstract

This invention provides a low-cost, bimodal particle size distribution titanium-based powder for additive manufacturing, titanium-based parts, and a method for preparing the same. The method utilizes two different medium particle sizes D... 50 Using near-spherical titanium-based powder as raw material, a near-spherical bimodal particle size distribution titanium-based powder with good uniformity is obtained by wet mixing of suspension and rotary degreasing in a furnace. Various near-spherical bimodal particle size distribution titanium-based powders can also be prepared. The difference between these powders lies in the different particle size ratios and mass ratios of the two raw material powders used. The bulk density and flowability of each bimodal powder are tested to determine the range of particle size ratios and mass ratios of the two powders in near-spherical bimodal particle size distribution powders with high bulk density and flowability. This guides the preparation of high-quality near-spherical bimodal particle size distribution titanium-based powders for additive manufacturing. Ultimately, additive manufacturing technology is used to prepare high-performance, low-cost titanium-based parts to meet the stringent performance requirements of titanium components in high-end fields such as aerospace.

Description

Low-cost additive manufacturing of bimodal particle size distribution titanium-based powder, titanium-based parts and their preparation methods Technical Field

[0001] This invention relates to the field of metal material preparation technology, specifically to a low-cost additive manufacturing bimodal particle size distribution titanium-based powder, titanium-based parts, and their preparation methods. Background Technology

[0002] Ti-6Al-4V alloy is currently the most widely used titanium alloy and one of the most important engineering materials. Due to its high specific strength, heat and corrosion resistance, and excellent biocompatibility, it has been widely applied in strategic emerging industries such as aerospace, marine, and biomedicine. However, due to its high activity, high melting point, and low thermal conductivity, traditional processes such as casting and forging face challenges in fabricating complex structures, low material utilization, high production costs, and long production cycles when manufacturing titanium parts. Additive manufacturing, as an emerging digital forming technology, has a completely different forming principle from traditional subtractive manufacturing. Based on the discrete-stacking principle, it enables direct manufacturing driven by three-dimensional data, offering high design freedom and demonstrating unique advantages in the low-cost, high-efficiency, and high-precision fabrication of high-performance, complex-structure titanium products. Therefore, in recent years, additive manufacturing of Ti-6Al-4V alloy technology has received widespread attention and research from materials scientists and industry. However, its industrial application still faces challenges in achieving high performance and low cost.

[0003] The cost of additive manufacturing of Ti-6Al-4V alloys is closely related to the price of raw material powder. Therefore, in recent years, both domestic and international research and development efforts have focused on reducing the cost of titanium alloy powders for additive manufacturing. Commonly employed techniques include plasma spheroidization, spray granulation, and high-temperature ball milling to shape and modify hydrogenated dehydrogenated (HDH) titanium powder, which has poor flowability but is inexpensive (around 250 RMB / kg), to obtain powder raw materials that meet the requirements of additive manufacturing. Although this technology has significantly reduced the cost of powders used in additive manufacturing, thereby reducing the production cost of formed parts, the performance of these parts still falls short of the increasingly stringent requirements for key titanium alloy components in high-end equipment manufacturing fields such as aerospace. Related research indicates that powder characteristics such as loose packing density and particle size distribution have a significant impact on the performance of additively manufactured parts. For example, loose packing density can influence the molten pool dynamics by affecting the powder bed density, thereby controlling the formation of defects such as porosity in the formed parts; and particle size distribution can influence the grain size of the part through its inherent genetic characteristics with the grain size of the part, thus controlling its performance. Therefore, exploring alternative approaches to improve the performance of additively manufactured titanium parts by controlling the properties of raw material powders is one of the main directions for future research in the field of titanium material additive manufacturing. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the main objective of this invention is to provide a low-cost additive manufacturing method for bimodal particle size distribution titanium-based powder, titanium-based parts, and their preparation methods. This preparation method uses two different medium particle sizes D... 50 Using near-spherical titanium-based powder as raw material, a near-spherical bimodal particle size distribution titanium-based powder with good uniformity is obtained by wet mixing of suspension and degreasing in a furnace. Finally, high-performance and low-cost titanium-based parts are prepared by additive manufacturing technology to meet the stringent performance requirements of titanium parts in high-end fields such as aerospace.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing a low-cost titanium-based powder with a bimodal particle size distribution for additive manufacturing is provided.

[0006] The method for preparing the low-cost additive manufacturing bimodal particle size distribution titanium-based powder includes the following steps:

[0007] Using particle size distribution methods with two different medium particle sizes D 50 The titanium-based powder is the raw material powder; among which, two different particle sizes D 50 Titanium-based powders are referred to as fine powder and coarse powder, respectively.

[0008] The raw material powder is placed in a suspension and stirred for a certain period of time to obtain a mixed powder slurry;

[0009] Under a protective atmosphere, the mixed powder slurry is degreased to obtain the titanium-based powder with bimodal particle size distribution.

[0010] In this invention, various near-spherical bimodal titanium-based powders with different particle sizes are prepared using the above-described method. The difference between these various bimodal particle size distribution powders lies in the different particle size ratios and mass ratios of the coarse and fine powders used. The bulk density and flowability of each bimodal particle size distribution powder are tested, thereby proposing a modified Horsfield dense packing theory applicable to near-spherical powders. This theory aims to determine the range of particle size ratios and mass ratios of the coarse and fine powders in near-spherical bimodal particle size distribution powders with high bulk density and flowability, and to guide the preparation of high-quality near-spherical bimodal particle size distribution titanium-based powders for additive manufacturing.

[0011] Furthermore, the fine powder has a particle size ≤ 20 μm, and the coarse powder has a particle size of 20–80 μm, excluding the endpoint value of 20 μm;

[0012] Preferably, the fine powder and the coarse powder have a medium particle size D. 50 The ratio is 0.414:1 to 0.385:1;

[0013] Preferably, the mass ratio of the fine powder to the coarse powder is 1:9 to 4:6.

[0014] Furthermore, the bimodal particle size distribution titanium-based powder is a near-spherical powder;

[0015] The titanium-based powder is titanium powder or titanium alloy powder;

[0016] Preferably, the titanium alloy powder includes, but is not limited to, Ti-6Al-4V alloy powder.

[0017] Furthermore, the suspension is a mixture of polyethylene glycol 4000 and anhydrous ethanol, or a mixture of polyethylene glycol 4000 and deionized water.

[0018] Preferably, the mass of the polyethylene glycol 4000 is 0.5% to 2% of the total mass of the raw material powder;

[0019] Preferably, the mass of the raw material powder is 60-80% of the total mass of the mixed powder slurry.

[0020] Furthermore, the stirring speed is 200-500 r / min, and the stirring time is 2-8 h;

[0021] Preferably, the stirring is carried out under a high-purity argon protective atmosphere.

[0022] Furthermore, the degreasing treatment temperature is 100-150℃, the heating rate is 1-3℃ / min, and the degreasing time is 1-2h;

[0023] Preferably, the protective gas is high-purity argon.

[0024] To achieve the above objectives, according to a second aspect of the present invention, a low-cost titanium-based powder with a bimodal particle size distribution for additive manufacturing is provided.

[0025] The low-cost additive manufacturing titanium-based powder with bimodal particle size distribution is prepared by the above-described method. The bimodal particle size distribution titanium-based powder has a particle size ≤80μm, a flowability of 40–46 s / 50g, and a bulk density of 2.35–2.45 g / cm³. 3 .

[0026] To achieve the above objectives, according to a third aspect of the present invention, a method for preparing high-performance titanium-based parts is provided.

[0027] The preparation method of this titanium-based component includes the following steps:

[0028] The aforementioned low-cost additive manufacturing bimodal particle size distribution titanium-based powder is used as the raw material;

[0029] Selective laser melting technology is used to prepare titanium or titanium alloy parts of a specified shape; wherein the laser power is 150-225W, the scanning speed is 600-1400mm / s, the scanning interval is 0.1-0.14mm, and the powder layer thickness is 20-30μm.

[0030] To achieve the above objectives, according to a fourth aspect of the present invention, a Ti-6Al-4V alloy part is provided.

[0031] The Ti-6Al-4V alloy component was prepared using the above-mentioned method.

[0032] The grain size of the Ti-6Al-4V alloy parts exhibits a bimodal distribution; the average grain size of the submicron-sized grains is 0.68–0.93 μm, and the average grain size of the micron-sized grains is 1.74–2.96 μm.

[0033] Furthermore, the Ti-6Al-4V alloy part has a density ≥99.07%, a surface roughness ≤3.5Ra, a tensile strength of 1168.4~1195.6MPa, and an elongation of 13.8~14.9%.

[0034] This invention proposes an additive manufacturing method for producing low-cost, high-performance titanium alloy parts with complex structures using near-spherical powders with a bimodal particle size distribution. Specifically, near-spherical titanium-based powders with different medium particle sizes are used as the initial powder. High-quality near-spherical titanium-based powders with a bimodal particle size distribution for additive manufacturing are prepared by wet powder mixing combined with inert gas-protected rotary degreasing technology. Finally, high-performance, low-cost titanium alloy parts are prepared using additive manufacturing technology.

[0035] The preparation method of this invention has the following advantages:

[0036] 1) Compared with conventional gas atomization and rotating electrode atomization of spherical titanium powder, the near-spherical titanium alloy powder preparation process used in this invention is simple, has a high powder yield, and low cost, which can effectively reduce the production cost of additive manufacturing titanium alloy parts.

[0037] 2) The wet mixing method of PEG4000 suspension proposed in this invention can fully disperse two powder particles of different sizes under the combined action of solute traction, magnetic stirring and centrifugal force, and obtain a uniform mixed powder slurry, thus laying the foundation for the preparation of additive manufacturing raw materials with bimodal dispersion. In this invention, the content of PEG4000 is 0.5% to 2% of the total mass of the two powders. If the content is too low, it will not play a dispersing and traction role, and it will be difficult to obtain a uniformly distributed bimodal particle size distribution powder. If the content is too high, the viscosity of the suspension will be too high, and problems such as powder agglomeration will occur during the mixing process, and it will also be impossible to obtain a uniformly distributed bimodal particle size distribution powder.

[0038] 3) The high-temperature degreasing treatment with furnace rotation is carried out under the protection of flowing high-purity argon gas. The mixed powder slurry rotates with the furnace, causing PEG4000 to be completely pyrolyzed into smaller molecules and removed, without introducing impurities such as oxygen and carbon. Therefore, the bimodal particle size distribution powder obtained by this invention is pure and uniform, which can solve the problems of uneven powder and the introduction of metal elements and impurities such as oxygen and carbon contained in the grinding balls by long-term ball milling mixing in traditional ball milling processes. This improves the uniformity, stability and controllability of the density and mechanical properties of the parts, and helps to obtain high-performance and uniformly stable additive manufacturing titanium alloy parts, greatly improving the service performance of the parts.

[0039] 4) This invention proposes a modified Horsfield dense packing theory applicable to near-spherical powders. Specifically, it utilizes the face-centered cubic structure in the metal crystal packing model to obtain packing models for near-spherical powders of different particle sizes, thereby determining the medium particle size D of coarse and fine powders in near-spherical bimodal distribution powders used in additive manufacturing. 50 The range of the ratio of particle size to mass provides theoretical guidance for the preparation of high-quality bimodal near-spherical titanium-based powders for additive manufacturing.

[0040] 5) Compared with powders with a single-peak particle size distribution, the powder with a bi-peak particle size distribution proposed in this invention can effectively improve the powder bed density by filling the pores between large particles with small particles, thereby improving the thermal conductivity of the material. This allows for the production of parts with superior density, surface quality, and mechanical properties without changing the process parameters. In addition, the bi-peak particle size distribution powder with a wider particle size distribution range causes the laser to be absorbed by the substrate and the surrounding environment only after multiple reflections between the powder particles, which improves the laser energy absorption rate. This allows for high-efficiency processing and preparation at a higher scanning speed when the laser power is the same.

[0041] 6) Due to the influence of powder genetic characteristics, the grain size distribution of the part is bimodal, with submicron and micron scales. Fine grains increase the total area of ​​grain boundaries, thereby increasing the resistance to dislocation migration and effectively improving the strength of the alloy. Meanwhile, coarse grains can accommodate more dislocations, thereby improving the plasticity of the alloy. Therefore, the coordinated effect of the dual-scale structure makes the titanium-based part have both high strength and high plasticity.

[0042] 7) The powder particle size distribution method expands the particle size range of powders used in additive manufacturing (single-peak powder 15-53μm, bi-peak powder ≤80μm), improves the utilization rate of coarse powder with a particle size >53μm and fine powder with a particle size of 0-20μm, and can further reduce the cost of raw material powders; in addition, selective laser melting technology has a short process cycle, high material utilization rate, uniform and fine part structure, and can accurately control the topology of parts, making it an important process for the preparation of complex structural parts that integrate high precision and high performance. Attached Figure Description

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0044] Figure 1 shows the morphology of the near-spherical bimodal particle size distribution Ti-6Al-4V alloy powder prepared in Example 4 of the present invention. Detailed Implementation

[0045] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0046] According to a specific embodiment of the present invention, a low-cost titanium-based powder with bimodal particle size distribution for additive manufacturing and a method for preparing the same are provided.

[0047] The method for preparing high-quality bimodal near-spherical titanium-based powder for additive manufacturing in this invention includes the following steps:

[0048] 1) Using two different medium particle sizes D 50 The titanium-based powder is the raw material powder; among which, two different particle sizes D 50 Titanium-based powders are referred to as fine powder and coarse powder, respectively.

[0049] In the embodiments of the present invention, the titanium-based powder is a near-spherical powder, with the fine powder having a particle size ≤20μm and the coarse powder having a particle size of 20-80μm and excluding the endpoint value of 20μm.

[0050] In an embodiment of the present invention, the ratio of the medium particle size of the fine powder to the coarse powder is 0.414:1 to 0.385:1.

[0051] In embodiments of the present invention, the mass ratio of fine powder to coarse powder can be 1:9 to 4:6.

[0052] It is worth mentioning that a modified Horsfield dense packing theory can be used to obtain near-spherical bimodal particle size distribution powders with high bulk density. Specifically, the face-centered cubic structure in the metal crystal packing model is used to obtain packing models for near-spherical powders of different particle sizes, thereby determining the medium particle size D of coarse and fine powders in the near-spherical bimodal distribution powder. 50 The ratio of their components and the ratio of their masses.

[0053] As an embodiment of the present invention, the titanium-based powder is titanium powder or titanium alloy powder; wherein, titanium alloy powder includes, but is not limited to, Ti-6Al-4V alloy powder.

[0054] 2) Place the raw material powder in a suspension and stir for 2-8 hours at a speed of 200-500 r / min to obtain a mixed powder slurry.

[0055] In embodiments of the present invention, stirring can be carried out under a protective atmosphere of high-purity argon.

[0056] In embodiments of the present invention, the suspension is a mixture of polyethylene glycol 4000 and anhydrous ethanol, or a mixture of polyethylene glycol 4000 and deionized water.

[0057] As an embodiment of the present invention, the mass of polyethylene glycol 4000 is 0.5 to 2% of the total mass of the raw material powder.

[0058] As an embodiment of the present invention, the mass of the raw material powder is 60-80% of the total mass of the mixed powder slurry.

[0059] 3) Under a protective atmosphere, the mixed powder slurry is degreased to obtain titanium-based powder with a bimodal particle size distribution.

[0060] In an embodiment of the present invention, the degreasing treatment temperature is 100-150°C, the heating rate is 1-3°C / min, and the degreasing time is 1-2 hours.

[0061] In embodiments of the present invention, the protective gas can be high-purity argon.

[0062] It should be noted that the obtained near-spherical bimodal particle size distribution titanium-based powder can be vacuum-encapsulated and stored for use in selective laser melting (SLM) to prepare titanium-based parts, especially Ti-6Al-4V alloy parts. Furthermore, a small amount of powder can be taken for relevant tests before vacuum encapsulation. Specifically, the morphology, particle size distribution, flowability, and loose density of the mixed powder can be observed using a scanning electron microscope, a laser particle size analyzer, and a Hall effect flow meter (funnel diameter 5 mm).

[0063] The titanium-based powder with bimodal particle size distribution prepared by the method of this invention has a particle size ≤80μm, a flowability of 40-46s / 50g, and a loose packing density of 2.35-2.45g / cm³. 3 .

[0064] According to a specific embodiment of the present invention, an additive manufacturing method for high-performance titanium or titanium alloy parts is also provided.

[0065] The additive manufacturing method of this invention includes the following steps:

[0066] Use SOLIDWORKS software to create a 3D model of the required part shape and then export it.

[0067] The 3D model is sliced ​​into layers, and the resulting 2D data is input into the metal printing equipment.

[0068] Using the aforementioned high-quality bimodal near-spherical titanium-based powder for additive manufacturing as raw material, titanium or titanium alloy parts of a specified shape are prepared by selective laser melting (SLM) technology; wherein the laser power is 150-225W, the scanning speed is 600-1400mm / s, the scanning interval is 0.1-0.14mm, and the powder layer thickness is 20-30μm.

[0069] The Ti-6Al-4V alloy parts prepared by the above-mentioned preparation method in this invention have a bimodal grain size distribution; wherein the average submicron grain size is 0.68-0.93 μm and the average micron grain size is 1.74-2.96 μm.

[0070] The Ti-6Al-4V alloy parts prepared in this invention have a density >99.07%, a surface roughness <3.5Ra, a tensile strength of 1168.4~1195.6MPa, and an elongation of 13.8~14.9%.

[0071] In this invention, the density, surface roughness, tensile strength, and elongation of the prepared parts are tested using Archimedes' drainage method, laser confocal microscopy, and a tensile testing machine, respectively.

[0072] It is worth mentioning that before the test, the parts are ultrasonically cleaned in alcohol for a certain time, such as 20 minutes, and then dried in a vacuum drying oven for a certain time, such as 30 minutes. The drying temperature can be 60℃ to ensure the accuracy of the test data.

[0073] The following detailed description, through specific embodiments, illustrates the preparation of low-cost additive manufacturing titanium-based powder with bimodal particle size distribution and the performance of the resulting Ti-6Al-4V alloy parts.

[0074] Example 1:

[0075] Two near-spherical Ti-6Al-4V alloy powders with particle sizes ranging from 3 to 20 μm and 20 to 53 μm, respectively, were weighed at a mass ratio of 4:6. These powders were placed in a beaker containing a suspension of PEG4000 (anhydrous ethanol), with PEG4000 accounting for 1% of the total mass of the two powders. The total mass of the two powders accounted for 70% of the total mass of the slurry. Under high-purity argon protection, the two powders of different particle sizes were mixed uniformly using a magnetic stirrer at a speed of 300 r / min for 5 h. The resulting mixed powder slurry was then placed in a high-temperature rotary furnace for degreasing. High-purity argon was used as the protective gas. The degreasing temperature was 130℃, the heating rate was 1.5℃ / min, and the holding time was 1.5 h. After furnace cooling, near-spherical bimodal Ti-6Al-4V alloy powder with a particle size distribution was obtained and vacuum-sealed for storage. Before sealing, a small amount of powder was taken for tests on powder morphology, particle size, and flowability. The results are detailed in Table 1.

[0076] The additive manufacturing method for high-performance titanium alloy parts using low-cost, near-spherical bimodal particle size distribution Ti-6Al-4V alloy powder as raw material includes the following steps:

[0077] S1: Use SOLIDWORKS software to draw a 3D model according to the required part shape and export it;

[0078] S2: Import the CAD model into the rapid prototyping auxiliary software Materialise Magics, perform layer slicing processing to obtain two-dimensional data information, and input the obtained two-dimensional data information into the metal printing equipment. The specific process parameters are: laser power 200W, scanning speed 1200mm / s, scanning spacing 0.12mm, powder layer thickness 30μm.

[0079] S3: Using the near-spherical bimodal particle size distribution Ti-6Al-4V alloy powder obtained above as raw material, titanium parts of a specified shape are prepared by selective laser melting technology;

[0080] S4: Printing is complete. After the substrate temperature cools to room temperature, remove the substrate and cut the part from the substrate using wire cutting.

[0081] S5: The part obtained in S4 is ultrasonically cleaned in alcohol for 20 minutes, and then dried in a vacuum drying oven for 30 minutes at a temperature of 60°C.

[0082] S6: The average grain size of the part was statistically analyzed using Image-Pro Plus. The density, surface roughness, tensile strength, and elongation of the part obtained after step S5 were tested by Archimedes' drainage method, laser confocal microscopy, and tensile testing machine. The results are detailed in Table 2.

[0083] Examples 2 and 3 used the same preparation process as Example 1, except for the characteristics of the raw material powder, the bimodal powder, and the selective laser melting preparation process parameters. Example 4 used the same preparation process as the bimodal particle size distribution powder in Example 1, except for the composition of the raw material powder. The characteristics of the near-spherical bimodal particle size distribution powder obtained in Examples 1 to 4, the properties of the Ti-6Al-4V parts prepared in Examples 1 to 3, the bimodal particle size distribution powder in Examples 1 to 4, and the preparation process parameters of the Ti-6Al-4V parts in Examples 1 to 3 are summarized in Tables 1 to 3.

[0084] Table 1. Summary of powder properties of bimodal particle size distribution titanium-based powders in Examples 1-4

[0085]

[0086] Table 2 Summary of the properties of Ti-6Al-4V alloy parts prepared in Examples 1-3

[0087] Part Performance Examples 1 Example 2 Example 3 Submicron Average Grain Size / μm 0.85 0.93 0.68 Micron Average Grain Size / μm 2.48 2.96 1.74 Density / % 99.18 99.76 99.07 Surface Roughness / Ra 3.4 3.2 3.5 Tensile Strength / MPa 1159.8 1168.4 1195.6 Elongation / % 14.9 14.4 13.8 surface

[0088] Table 3. Summary of raw material powders in Examples 1-4 and process parameters for the preparation of Ti-6Al-4V parts in Examples 1-3.

[0089]

[0090] The following will compare the performance of the Ti-6Al-4V alloy parts prepared in Examples 1-3 and the parts prepared in Comparative Examples 1-6.

[0091] I. Experimental Subjects

[0092] The Ti-6Al-4V alloy parts prepared in Examples 1-3 and the Ti-6Al-4V alloy parts prepared in Comparative Examples 1-6, as well as the powders prepared in Examples 1-3 and Comparative Examples 1-8, wherein:

[0093] Comparative Example 1:

[0094] Ti-6Al-4V alloy parts were prepared using Ti-6Al-4V powder with the same particle size distribution characteristics as in Example 1, and using the same preparation process as in Example 1. The only difference was the preparation method of the raw material powder: in Example 1, the raw material powder was a bimodal particle size distribution powder prepared by wet mixing with PEG4000 suspension combined with furnace rotary degreasing technology, while in Comparative Example 1, the raw material powder was a bimodal particle size distribution powder obtained by ball milling mixing. The specific powder characteristics and part performance are detailed in Tables 4 and 5.

[0095] Comparative Example 2:

[0096] Ti-6Al-4V alloy parts were prepared using Ti-6Al-4V powder with a particle size range that is basically the same as that in Example 1, and using the same preparation process as in Example 1. The only difference is the particle size distribution characteristics of the raw material powder: the powder particle size in Example 1 shows a bimodal particle size distribution, while the powder particle size in Comparative Example 2 shows a unimodal distribution. For details of the specific powder characteristics and the performance of the parts, please refer to Tables 4 and 5.

[0097] Comparative Example 3:

[0098] Ti-6Al-4V alloy parts were prepared using Ti-6Al-4V powder with the same particle size distribution characteristics as in Example 2, and using the same preparation process as in Example 2. The only difference was the preparation method of the raw material powder: in Example 2, the raw material powder was a bimodal particle size distribution powder prepared by wet mixing with PEG4000 suspension combined with furnace rotary degreasing technology, while in Comparative Example 3, the raw material powder was a bimodal particle size distribution powder obtained by ball milling mixing. The specific powder characteristics and part performance are detailed in Tables 4 and 5.

[0099] Comparative Example 4:

[0100] Ti-6Al-4V alloy parts were prepared using Ti-6Al-4V powder with the same particle size range as in Example 2 and the same preparation process as in Example 2. The only difference was the particle size distribution characteristics of the raw material powder: the powder particle size in Example 2 showed a bimodal particle size distribution, while the powder particle size in Comparative Example 4 showed a unimodal distribution. For details of the powder characteristics and the performance of the parts, please refer to Tables 4 and 5.

[0101] Comparative Example 5:

[0102] Ti-6Al-4V parts were prepared using Ti-6Al-4V powder with the same particle size distribution characteristics as in Example 3, and using the same preparation process as in Example 3. The only difference was the preparation method of the raw material powder: in Example 3, the raw material powder was a bimodal particle size distribution powder prepared by wet mixing of PEG4000 suspension combined with furnace rotary degreasing technology, while in Comparative Example 5, the raw material powder was a bimodal particle size distribution powder obtained by ball milling mixing. The specific powder characteristics and part performance are detailed in Tables 4 and 5.

[0103] Comparative Example 6:

[0104] Ti-6Al-4V alloy parts were prepared using Ti-6Al-4V powder with the same particle size range as in Example 3 and the same preparation process as in Example 3. The only difference was the particle size distribution characteristics of the raw material powder: the powder particle size in Example 3 showed a bimodal particle size distribution, while the powder particle size in Comparative Example 6 showed a unimodal distribution. For a detailed description of the powder characteristics and the performance of the parts, please refer to Tables 4 and 5.

[0105] Comparative Example 7:

[0106] Pure titanium powder with the same particle size distribution characteristics as in Example 4 was used as raw material. The only difference was the preparation method of the raw material powder: in Example 4, the raw material powder was a bimodal particle size distribution powder prepared by wet mixing of PEG4000 suspension combined with furnace rotary degreasing technology, while in Comparative Example 7, the raw material powder was a bimodal particle size distribution powder obtained by ball milling mixing. The specific powder characteristics are detailed in Table 4.

[0107] Comparative Example 8:

[0108] Pure titanium powder with the same particle size distribution range as in Example 4 was used as raw material. The only difference was the particle size distribution characteristics of the raw material powder: the powder particle size in Example 4 showed a bimodal distribution, while the powder particle size in Comparative Example 8 showed a unimodal distribution. For details of the specific powder characteristics, please refer to Table 4.

[0109] Table 4 summarizes the powder properties of the raw material powders in Comparative Examples 1–8.

[0110]

[0111] Table 5 summarizes the properties of the Ti-6Al-4V alloy parts prepared in Comparative Examples 1–6.

[0112]

[0113] Analysis of the data in the table shows that the bimodal particle size distribution titanium-based powders prepared in Examples 1-4 have a flowability in the range of 40-46 s / 50 g and a loose packing density of 2.35-2.45 g / cm³. 3 Due to the influence of powder genetic characteristics, the Ti-6Al-4V parts prepared by selective laser melting using this bimodal particle size distribution powder as raw material exhibit a bimodal size distribution of submicron (0.68-0.93 μm) and micron (1.74-2.96 μm). The prepared parts have high density, reaching over 99%, good surface quality, with a surface roughness value of 3.2-3.5 Ra, and excellent mechanical properties, with a room temperature tensile strength of 1168.4-1195.6 MPa and an elongation in the range of 13.8%-14.9%.

[0114] By comparing Example 1 with Comparative Example 1, Example 2 with Comparative Example 3, Example 3 with Comparative Example 5, and Example 4 with Comparative Example 7, it can be seen that, when having the same particle size distribution characteristics, compared with traditional ball milling and powder mixing, the bimodal particle size distribution powder prepared by the wet powder mixing combined with furnace rotary degreasing technology proposed in this invention has higher flowability and bulk density due to its higher uniformity. Specifically, flowability: 43 vs. 46 s / 50g, 40 vs. 44 s / 50g, 46 vs. 51 s / 50g, 42 vs. 46 s / 50g; bulk density: 2.38 vs. 2.32 g / cm³. 3 2.45 vs. 2.34 g / cm³ 3 2.35 vs. 2.24 g / cm³ 3 2.39 vs. 2.33 g / cm³ 3 Furthermore, the prepared parts exhibit superior performance, specifically: high density: 99.18 vs. 98.32%, 99.76 vs. 98.58%, 99.07 vs. 97.46%; low surface roughness: 3.4 vs. 4.1 Ra, 3.2 vs. 3.8 Ra, 3.5 vs. 4.2 Ra; high tensile strength: 1159.8 vs. 1108.9 MPa, 1168.4 vs. 1045.9 MPa, 1195.6 vs. 1069.5 MPa; and high elongation: 14.9 vs. 12.5%, 14.4 vs. 11.7%, 13.8 vs. 12.3%.

[0115] By comparing Example 1 with Comparative Example 2, Example 2 with Comparative Example 4, Example 3 with Comparative Example 6, and Example 4 with Comparative Example 8, it can be seen that, when the particle size distribution range is the same, compared with single-peak powder, the bimodal particle size distribution powder prepared by the wet mixing combined with furnace rotary degreasing technology proposed in this invention has a higher bulk density due to the combination of large and small particle sizes, specifically: 2.38 vs. 2.27 g / cm³. 32.45 vs. 2.30 g / cm³ 3 2.35 vs. 2.28 g / cm³ 3 2.39 vs. 2.30 g / cm³ 3 Furthermore, the prepared parts exhibit superior performance, specifically: high density: 99.18 vs. 97.71%, 99.76 vs. 98.25%, 99.07 vs. 97.62%; low surface roughness: 3.4 vs. 3.8 Ra, 3.2 vs. 3.9 Ra, 3.5 vs. 4.4 Ra; high tensile strength: 1159.8 vs. 1076.7 MPa, 1168.4 vs. 1051.5 MPa, 1195.6 vs. 1082.8 MPa; and high elongation: 14.9 vs. 13.1%, 14.4 vs. 12.8%, 13.8 vs. 13.1%.

[0116] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing low-cost titanium-based powder with bimodal particle size distribution for additive manufacturing, characterized in that, Includes the following steps: Using particle size distribution methods with two different medium particle sizes D 50 The titanium-based powder is the raw material powder; among which, two different particle sizes D 50 The titanium-based powders are referred to as fine powder and coarse powder, respectively. The raw material powders are placed in a suspension and stirred for a certain period of time to obtain a mixed powder slurry. The suspension is a mixture of polyethylene glycol 4000 and anhydrous ethanol, or a mixture of polyethylene glycol 4000 and deionized water. Under a protective atmosphere, the mixed powder slurry is subjected to rotary degreasing treatment in a furnace. The degreasing treatment temperature is 100~150℃, the heating rate is 1~3℃ / min, and the degreasing time is 1~2 h to obtain the titanium-based powder with bimodal particle size distribution.

2. The preparation method according to claim 1, characterized in that, The fine powder has a particle size ≤ 20 μm, and the coarse powder has a particle size of 20~80 μm, excluding the endpoint value of 20 μm.

3. The preparation method according to claim 1, characterized in that, The fine powder and the coarse powder have a medium particle size D. 50 The ratio is 0.414:1 to 0.385:

1.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the fine powder to the coarse powder is 1:9 to 4:

6.

5. The preparation method according to claim 1, characterized in that, The bimodal particle size distribution titanium-based powder is a near-spherical powder; the titanium-based powder is titanium powder or titanium alloy powder.

6. The preparation method according to claim 5, characterized in that, The titanium alloy powder includes Ti-6Al-4V alloy powder.

7. The preparation method according to claim 1, characterized in that, The mass of the polyethylene glycol 4000 is 0.5 to 2% of the total mass of the raw material powder.

8. The preparation method according to claim 1, characterized in that, The mass of the raw material powder is 60-80% of the total mass of the mixed powder slurry.

9. The preparation method according to claim 1, characterized in that, The stirring speed is 200~500 r / min, and the stirring time is 2~8 h.

10. The preparation method according to claim 1, characterized in that, The stirring was carried out under a protective atmosphere of high-purity argon.

11. The preparation method according to claim 1, characterized in that, The protective gas is high-purity argon.

12. A low-cost titanium-based powder with bimodal particle size distribution for additive manufacturing, characterized in that, The titanium-based powder with bimodal particle size distribution is prepared by the method described in any one of claims 1-11, wherein the particle size is ≤80μm, the flowability is 40~46s / 50g, and the loose packing density is 2.35~2.45g / cm³. 3 .

13. A method for preparing a titanium-based component, characterized in that, The method includes the following steps: using the low-cost additive manufacturing bimodal particle size distribution titanium-based powder as described in claim 12 as raw material; and using selective laser melting technology to prepare titanium or titanium alloy parts of a specified shape; wherein the laser power is 150~225W, the scanning speed is 600~1400mm / s, the scanning interval is 0.1~0.14mm, and the powder layer thickness is 20~30μm.

14. A Ti-6Al-4V alloy component, characterized in that, It is prepared by the preparation method described in claim 13; the grain size of the Ti-6Al-4V alloy part is bimodal; wherein the average grain size of the submicron grains is 0.68~0.93μm, and the average grain size of the micron grains is 1.74~2.96μm.

15. The Ti-6Al-4V alloy part as described in claim 14, characterized in that, The Ti-6Al-4V alloy parts have a density ≥99.07%, a surface roughness ≤3.5Ra, a tensile strength of 1168.4~1195.6MPa, and an elongation of 13.8~14.9%.

Images