High-performance titanium alloy spherical powder and preparation method thereof

Abstract

The invention relates to high-performance titanium alloy spherical powder and a preparation method thereof, and belongs to the technical field of additive manufacturing. The preparation method of the high-performance titanium alloy spherical powder comprises the following steps: preparing pre-alloyed powder through electrode induction gas atomization; the pre-alloyed powder is subjected to plasma spheroidizing treatment, and spherical powder is obtained; and the spherical powder is screened. A mode of combining electrode induction gas atomization and plasma spheroidizing treatment is adopted, in the electrode induction gas atomization stage, molten alloy liquid is atomized into tiny liquid drops, and then the tiny liquid drops are rapidly cooled and solidified to form initial pre-alloy powder; and in the plasma spheroidizing stage, under the action of high-temperature plasma, the pre-alloyed powder is molten again and forms a sphere under the action of surface tension, and then the pre-alloyed powder is rapidly cooled and solidified. By means of the combined mode, the powder yield can be guaranteed, and the sphericity degree and the fluidity can be improved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a high-performance titanium alloy spherical powder and its preparation method. Background Technology

[0002] With the development of additive manufacturing technology, the demand for high-quality spherical metal powders is increasing. Currently, the main methods for preparing metal powders include gas atomization, plasma rotating electrode method, and mechanical alloying method.

[0003] Electrode-induced gas atomization (EGIA) is a commonly used method for preparing metal powders. This method melts a metal electrode through induction heating and then uses high-pressure gas to atomize the molten metal into powder. However, traditional EGIA technology often neglects powder yield when considering powder sphericity; conversely, improving powder yield can lead to problems such as low sphericity and poor flowability. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a high-performance titanium alloy spherical powder and its preparation method, which improves powder yield while enhancing sphericity and flowability.

[0005] On one hand, the present invention provides a method for preparing high-performance titanium alloy spherical powder, comprising the following steps:

[0006] Step 1: Pre-alloyed powder is prepared by induction gas atomization via electrodes;

[0007] Step 2: Obtain spherical powder by plasma spheroidization treatment of the pre-alloyed powder;

[0008] Step 3: Screen the spherical powder.

[0009] Furthermore, in step one, the sensing power of the electrode sensing gas atomization is 45-55kW, the gas pressure is 4-6MPa, the gas flow rate is 40-60L / min, and the atomizing gas is argon.

[0010] Furthermore, in step one, the sensing power of the electrode sensing gas atomization is 50-55kW, the gas pressure is 5-6MPa, and the gas flow rate is 50-60L / min.

[0011] Furthermore, in the second step of plasma spheroidization treatment, the plasma power is 20-40kW, the argon or helium flow rate is 15-25L / min, and the powder delivery rate is 5-10g / min.

[0012] Furthermore, in the second step of plasma spheroidization treatment, the plasma power is 30-40kW.

[0013] Furthermore, in the second step of plasma spheroidization treatment, the flow rate of argon or helium is 20-25 L / min.

[0014] Furthermore, the titanium alloy is a Ti2AlNb alloy.

[0015] Furthermore, the alloy powder yield is above 86.5%.

[0016] Furthermore, the sphericity of the spherical powder is 97-98%; the Hall flow rate is 20-22 s / 50g; and the hollow powder rate is <1.7%.

[0017] On the other hand, the present invention provides a high-performance titanium alloy spherical powder, which is prepared by the preparation method described in the present invention.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] 1. Traditional single EIGA processes often require extreme optimization of atomization parameters (such as high gas pressure) to achieve high sphericity, but this leads to decreased yield, excessive fine powder, or an increase in hollow powder. This invention combines electrode-inducing gas atomization and plasma spheroidization. In the electrode-inducing gas atomization stage, the molten alloy liquid is atomized into tiny droplets, which are then rapidly cooled and solidified to form the initial pre-alloyed powder. In the plasma spheroidization stage, under the action of high-temperature plasma, the pre-alloyed powder is remelted and forms spherical shapes under surface tension, followed by rapid cooling and solidification. This combined approach not only ensures powder yield but also improves sphericity and flowability.

[0020] 2. In this invention, pre-alloyed powder is first prepared using optimized EIGA parameters (such as induction power of 45-55kW and gas pressure of 4-6MPa) to obtain a high initial yield (≥86.5%). Then, the pre-alloyed powder is subjected to secondary treatment by plasma spheroidization to effectively melt and spheroidize irregular particles and satellite powder, so that the sphericity of the final powder is significantly improved to 97-98%.

[0021] 3. In this invention, plasma spheroidization not only improves sphericity but also cleans and densifies the powder surface through high-temperature plasma, reducing surface adsorption and oxidation; simultaneously, it makes the powder composition more uniform. Combined with optimized process parameters (e.g., plasma power 20-40kW, argon or helium flow rate 10-25L / min), the final powder exhibits excellent Hall flow rate (20-22s / 50g), good flowability, and meets the high requirements for powder spreadability in additive manufacturing and other applications. Furthermore, this method controls the hollow powder ratio to an extremely low level (<1.7%), reducing defects in the final part (after additive printing) caused by internal porosity, and improving the overall quality and reliability of the powder product.

[0022] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0023] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0024] Figure 1 This is a graph showing the results of the hollow rate detection in Example 1;

[0025] Figure 2 This is a graph showing the results of the hollow rate detection in Example 3;

[0026] Figure 3 This is a graph showing the results of the hollow rate detection in Comparative Example 1;

[0027] Figure 4 This is a diagram showing the sphericity test results of Example 1;

[0028] Figure 5 This is a graph showing the sphericity test results for Example 3;

[0029] Figure 6 This is a diagram showing the sphericity test results for Comparative Example 1. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0031] With the development of additive manufacturing technology, the demand for high-quality spherical metal powders is increasing. Currently, the main methods for preparing metal powders include gas atomization, plasma rotating electrode method, and mechanical alloying method.

[0032] Electrode-induced gas atomization (EGIA) is a commonly used method for preparing metal powders. This method melts a metal electrode through induction heating and then uses high-pressure gas to atomize the molten metal into powder. However, traditional EGIA technology often neglects powder yield when considering powder sphericity; conversely, improving powder yield can lead to problems such as low sphericity and poor flowability.

[0033] Therefore, the present invention provides a method for preparing high-performance titanium alloy spherical powder, comprising the following steps:

[0034] Step 1: Pre-alloyed powder is prepared by induction gas atomization via electrodes;

[0035] Step 2: Obtain spherical powder by plasma spheroidization treatment of the pre-alloyed powder;

[0036] Step 3: Screen the spherical powder.

[0037] Compared to existing technologies, traditional single EIGA processes often require extreme optimization of atomization parameters (such as extremely high gas pressure) to achieve high sphericity, but this leads to decreased yield, excessive fine powder, or an increase in hollow powder. This invention employs a combination of electrode-inducing gas atomization and plasma spheroidization. In the electrode-inducing gas atomization stage, the molten alloy liquid is atomized into tiny droplets, which are then rapidly cooled and solidified to form the initial pre-alloyed powder. In the plasma spheroidization stage, under the action of high-temperature plasma, the pre-alloyed powder is remelted and forms spherical shapes under surface tension, followed by rapid cooling and solidification. This combination of methods not only ensures powder yield but also improves sphericity and flowability.

[0038] Specifically, in step one, the sensing power of the electrode sensing gas atomization is 45-55kW, the gas pressure is 4-6MPa, the gas flow rate is 40-60L / min, and the atomizing gas is argon.

[0039] It should be noted that the present invention first uses optimized EIGA parameters (such as induction power 45-55kW and gas pressure 4-6MPa) to prepare pre-alloyed powder, thereby obtaining a high initial yield (≥86.5%); then, the pre-alloyed powder is subjected to secondary treatment by plasma spheroidization, which effectively melts and spheroidizes irregular particles and satellite powder, thereby significantly improving the sphericity of the final powder to 97-98%.

[0040] In this invention, the induction power is controlled at 45-55kW to provide sufficient and stable thermal energy, ensuring that the titanium alloy electrode (such as Ti2AlNb) achieves sufficient and uniform superheat. This ensures complete melting of the titanium alloy, which is beneficial for effective gas atomization, resulting in a higher yield. If the induction power is below 45kW, insufficient superheat and incomplete melting will occur, leading to poor fluidity, difficulty in effective gas atomization, and a lower yield. If the induction power is too high, i.e., above 55kW, the excessively high temperature will exacerbate the volatilization of low-melting-point elements such as aluminum (Al) in the titanium alloy, altering the alloy composition and compromising the performance of the additively printed product or part. Furthermore, excessively high temperatures will lead to increased superheat, making it difficult for the gas inside the droplets to expand and escape, thus increasing the number of hollow powder particles.

[0041] Therefore, the induction power of the present invention can be 45kW, 46kW, 47kW, 48kW, 49kW, 50kW, 51kW, 52kW, 53kW, 54kW or 55kW.

[0042] In this invention, controlling the gas pressure to 4-6 MPa and the gas flow rate to 40-60 L / min provides sufficient kinetic energy to effectively break the molten metal flow into fine droplets, preventing excessive generation of ultrafine powder and ensuring a yield of over 86.5%. When the gas pressure is below 4 MPa and the gas flow rate is below 40 L / min, the gas cannot effectively break up the molten metal flow, leading to coarsening of the powder particle size. Simultaneously, the longer cooling and solidification time of the droplets can exacerbate oxidation and form irregularly shaped particles. When the gas pressure is above 6 MPa and the gas flow rate is above 60 L / min, excessive ultrafine powder is generated, which is easily lost during collection, thus reducing the effective yield.

[0043] In this invention, the gas pressure can be 4 MPa, 5 MPa, or 6 MPa. The gas flow rate can be 40 L / min, 42 L / min, 45 L / min, 48 L / min, 50 L / min, 53 L / min, 55 L / min, 57 L / min, 59 L / min, or 60 L / min.

[0044] Preferably, in step one, the sensing power of the electrode sensing gas atomization is 50-55kW, the gas pressure is 5-6MPa, and the gas flow rate is 50-60L / min.

[0045] In this invention, argon is chosen as the atomizing gas, which can provide inert protection for the molten titanium alloy and prevent the titanium alloy powder from reacting with nitrogen and oxygen at high temperatures; argon can also play a quenching role, which is beneficial to maintaining the accuracy of the composition of the pre-alloyed powder.

[0046] Specifically, in the second step of plasma spheroidization treatment, the plasma power is 20-40kW, the argon or helium flow rate is 15-25L / min, and the powder delivery rate is 5-10g / min.

[0047] It should be noted that in this invention, plasma spheroidization not only improves sphericity but also cleans and densifies the powder surface through high-temperature plasma, reducing surface adsorption and oxidation; simultaneously, it makes the powder composition more uniform. Combined with optimized process parameters (e.g., plasma power 20-40kW, argon or helium flow rate 10-25L / min, powder delivery rate 5-10g / min), the final powder exhibits excellent Hall flow rate (20-22s / 50g), good flowability, and meets the high requirements for powder spreadability in additive manufacturing and other applications. Furthermore, this method controls the hollow powder ratio to an extremely low level (<1.7%), reducing defects in the final part (after additive printing) caused by internal porosity, and improving the overall quality and reliability of the powder product.

[0048] In this invention, the plasma power is controlled at 20-40 kW. At this power, the temperature is high and the energy density is concentrated, allowing titanium alloy particles to reach a molten state in a short time. Under the action of surface tension, they form spherical shapes and then rapidly cool and solidify. If the plasma power is below 20 kW, only fine powder or the surface of the powder can be melted, while the center of coarser particles cannot be melted. Therefore, the sphericity cannot be guaranteed to meet the requirements, resulting in irregular particles and poor flow properties, thus making it unsuitable for use in manufacturing. If the plasma power is above 40 kW, excessive evaporation and burn-off of the powder lead to a decrease in both the composition and yield of the titanium alloy.

[0049] Therefore, the plasma power in this invention can be 20kW, 22kW, 25kW, 27kW, 29kW, 30kW, 33kW, 35kW, 37kW, 39kW or 40kW.

[0050] Preferably, in the second step of plasma spheroidization treatment, the plasma power is 30-40kW.

[0051] In this invention, the argon or helium flow rate is controlled at 10-25 L / min. The gas flow rate, combined with power, forms and stabilizes the plasma jet, transporting and protecting the powder. If the flow rate is below 10 L / min, the plasma jet is unstable, the high-temperature zone is shortened, and the powder may not be able to pass through the high-temperature zone, leading to uneven heating and failure to spheroidize. If the flow rate is above 25 L / min, the cooling effect is strong, greatly shortening the time the powder spends in the molten state, resulting in non-spherical spheroidization or a rough surface.

[0052] Therefore, in this invention, the flow rate of argon or helium can be controlled to be 10L / min, 11L / min, 12L / min, 13L / min, 14L / min, 15L / min, 16L / min, 17L / min, 18L / min, 19L / min, 20L / min, 21L / min, 22L / min, 23L / min, 24L / min or 25L / min.

[0053] Preferably, in the plasma spheroidization process of step two, the flow rate of argon or helium is 20-25 L / min.

[0054] In this invention, the powder conveying rate is controlled at 5-10 g / min to ensure production efficiency and spheroidization quality. At this rate, it is ensured that each powder particle absorbs sufficient and uniform heat, thereby achieving complete and uniform spheroidization. If the powder conveying rate is higher than 10 g / min, too much powder enters per unit time, the plasma energy is dispersed, the heat received by each powder particle is reduced, resulting in a large number of particles not completely melting, spheroidization failure, and the appearance of a large number of undeformed original particles.

[0055] Therefore, the powder conveying rate can be controlled at 5 g / min, 6 g / min, 7 g / min, 8 g / min, 9 g / min or 10 g / min in this invention.

[0056] Preferably, in the plasma spheroidization process of step two, the powder conveying rate is 6-8 g / min.

[0057] Specifically, the titanium alloy is a Ti2AlNb alloy.

[0058] It should be noted that the titanium alloy used in this invention is Ti2AlNb alloy, which is an intermetallic compound-based alloy, also known as an ordered orthorhombic titanium-aluminum alloy. In Ti2AlNb alloy, the Ti and Al elements have an extremely strong affinity for oxygen; even a trace amount of oxygen absorption will form brittle oxides, severely deteriorating the mechanical properties. Therefore, in preparing high-performance titanium alloy spherical powder, this invention uses argon or helium to continuously protect the powder during both the electrode induction gas atomization stage and the plasma spheroidization treatment stage.

[0059] It should be noted that overheating or improper cooling during the preparation of Ti2AlNb titanium alloy spherical powder can lead to coarse grains or the precipitation of harmful phases, thus damaging performance. Therefore, this invention employs a combination of electrode-induced gas atomization and plasma spheroidization treatment for preparation. The parameters for electrode-induced gas atomization are strictly controlled: induction power of 45-55 kW, gas pressure of 4-6 MPa, gas flow rate of 40-60 L / min, and argon as the atomizing gas. Similarly, the parameters for plasma spheroidization treatment are: plasma power of 20-40 kW, argon or helium flow rate of 15-25 L / min, and powder delivery rate of 5-10 g / min. These parameters facilitate the formation of fine metastable structures or amorphous surface layers, providing an ideal initial microstructure for controlled remelting during subsequent 3D printing.

[0060] To more clearly describe the present invention, the following embodiments and comparative examples are provided for further illustration.

[0061] Example 1

[0062] A method for preparing high-performance titanium alloy spherical powder includes the following steps:

[0063] Step 1: Pre-alloyed powder is prepared by induction gas atomization via electrodes;

[0064] Ti2AlNb alloy ingots were selected as raw materials and heated and melted in a crucible of an EGIA apparatus. The induction power was 50 kW, the atomizing gas pressure was 5 MPa, and the gas flow rate was 50 L / min.

[0065] Step 2: Obtain spherical powder by plasma spheroidization treatment of the pre-alloyed powder;

[0066] The pre-alloyed powder was fed into a plasma spheroidization apparatus for processing. The plasma power was 30 kW, argon was used as the protective gas with a flow rate of 20 L / min, and the powder conveying rate was 5 g / min. It was then rapidly cooled and solidified to obtain Ti2AlNb alloy powder with high sphericity.

[0067] Step 3: Screen the spherical powder.

[0068] The spherical powder obtained in step two was sieved to remove excessively large or small particles, resulting in alloy powder with a uniform particle size distribution. The powder sphericity reached 96.5%, the Hall flow rate was 20.95 s / 50 g, and the hollow powder ratio was 1.63%.

[0069] Example 2

[0070] The preparation process of Example 2 is largely the same as that of Example 1. The difference is that in Example 2, the plasma power is 30kW, helium is used as the protective gas, the helium flow rate is 20L / min, and the powder delivery rate is 5g / min.

[0071] The powder sphericity reached 97.1%, the Hall flow rate was 20.95s / 50g, and the hollow powder rate was 1.68%.

[0072] Example 3

[0073] The preparation process of Example 3 is largely the same as that of Example 1. The difference is that in Example 3, the plasma power is 35kW, helium is used as the protective gas, the helium flow rate is 25L / min, and the powder delivery rate is 10g / min.

[0074] The powder sphericity reached 97.7%, the Hall flow rate was 21.67 s / 50 g, and the hollow powder rate was 1.6%.

[0075] Comparative Example 1

[0076] The preparation process of Comparative Example 1 is largely the same as that of Example 1, except that Comparative Example 1 uses the EGIA process to prepare spherical Ti2AlNb powder, which specifically includes the following steps:

[0077] Step 1: Preparation of Ti2AlNb pre-alloyed powder by electrode-induced gas atomization (EGIA). Similar to Example 1, this example also uses the EGIA process to prepare pre-alloyed powder. Ti2AlNb alloy ingots are selected as raw materials. The EGIA process parameters are set as follows: induction power 45kW, argon gas is used as the protective gas for atomization, atomization gas pressure 8MPa, and gas flow rate 40L / min.

[0078] Step 2: Screening and post-processing of spherical powders

[0079] The spherical powder is sieved to remove oversized or undersized particles, resulting in alloy powder with a uniform particle size distribution.

[0080] The powder sphericity was 95%, the Hall flow rate was 19.76 s / 50 g, the hollow powder rate was 3.18%, but the alloy powder yield was 69.9%.

[0081] Comparative Example 2

[0082] The preparation process of Comparative Example 2 is largely the same as that of Example 1, except that in the electrode sensing gas atomization of Comparative Example 2, the sensing power is 40kW, the gas pressure is 3MPa, the gas flow rate is 35L / min, and the atomizing gas is argon.

[0083] The powder sphericity was 88.6%, the Hall flow rate was 18.46 s / 50 g, the hollow powder rate was 3.18%, but the alloy powder yield was 70.6%.

[0084] Comparative Example 3

[0085] The preparation process of Comparative Example 3 is largely the same as that of Example 1, except that in the electrode sensing gas atomization of Comparative Example 3, the sensing power is 60kW, the gas pressure is 8MPa, the gas flow rate is 65L / min, and the atomizing gas is argon.

[0086] The powder sphericity was 90.4%, the Hall flow rate was 19.23 s / 50 g, the hollow powder rate was 5.18%, but the alloy powder yield was 68.6%.

[0087] Comparative Example 4

[0088] The preparation process of Comparative Example 4 is largely the same as that of Example 1, except that the plasma power of Comparative Example 4 is 15kW, the argon flow rate is 10-25L / min, and the powder delivery rate is 4g / min.

[0089] The powder sphericity was 66.7%, the Hall flow rate was 17.35 s / 50 g, the hollow powder rate was 2.28%, and the alloy powder yield was 88.6%.

[0090] Comparative Example 5

[0091] The preparation process of Comparative Example 5 is largely the same as that of Example 1, except that the plasma power of Comparative Example 5 is 45kW, the argon flow rate is 30L / min, and the powder delivery rate is 15g / min.

[0092] The powder sphericity was 80.7%, the Hall flow rate was 16.23 s / 50 g, the hollow powder rate was 2.18%, and the alloy powder yield was 78.6%.

[0093] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing high-performance titanium alloy spherical powder, characterized in that, Includes the following steps: Step 1: Pre-alloyed powder is prepared by induction gas atomization via electrodes; Step 2: Obtain spherical powder by plasma spheroidization treatment of the pre-alloyed powder; Step 3: Screen the spherical powder.

2. The method for preparing high-performance titanium alloy spherical powder according to claim 1, characterized in that, In step one, the sensing power of the electrode sensing gas atomization is 45-55kW, the gas pressure is 4-6MPa, the gas flow rate is 40-60L / min, and the atomizing gas is argon.

3. The method for preparing high-performance titanium alloy spherical powder according to claim 2, characterized in that, In step one, the sensing power of the electrode sensing gas atomization is 50-55kW, the gas pressure is 5-6MPa, and the gas flow rate is 50-60L / min.

4. The method for preparing high-performance titanium alloy spherical powder according to claim 1, characterized in that, In the second step of plasma spheroidization, the plasma power is 20-40kW, the argon or helium flow rate is 15-25L / min, and the powder delivery rate is 5-10g / min.

5. The method for preparing high-performance titanium alloy spherical powder according to claim 4, characterized in that, In the second step of plasma spheroidization, the plasma power is 30-40kW.

6. The method for preparing high-performance titanium alloy spherical powder according to claim 4, characterized in that, In the second step of plasma spheroidization, the flow rate of argon or helium is 20-25 L / min.

7. The method for preparing high-performance titanium alloy spherical powder according to claim 1, characterized in that, The titanium alloy is a Ti2AlNb alloy.

8. The method for preparing high-performance titanium alloy spherical powder according to claim 1, characterized in that, The alloy powder yield is above 86.5%.

9. The method for preparing high-performance titanium alloy spherical powder according to claim 1, characterized in that, The sphericity of the spherical powder is 97-98%; the Hall flow rate is 20-22 s / 50g; and the hollow powder rate is <1.7%.

10. A high-performance titanium alloy spherical powder, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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