A method for preparing a titanium-aluminum alloy powder for additive manufacturing

Abstract

The application relates to a preparation method of a titanium-aluminum alloy powder for additive manufacturing. The method comprises the following steps: preparing a titanium-aluminum rod material, and processing the titanium-aluminum rod material to obtain a titanium-aluminum electrode rod material; placing the titanium-aluminum electrode rod material into an atomization chamber, and connecting one end of the titanium-aluminum electrode rod material with a connecting rod; performing vacuumizing treatment on the atomization chamber, and introducing inert gas; setting atomization powder preparation process parameters to prepare the titanium-aluminum electrode rod material; performing primary aluminum increasing treatment during the preparation of the titanium-aluminum electrode rod material to obtain a primary aluminum-increased titanium-aluminum alloy powder; and grading the primary aluminum-increased titanium-aluminum alloy powder according to particle size. The titanium-aluminum rod material with an aluminum content less than 46 at% is used for PREP powder preparation, and twice aluminum increasing treatment is adopted, so that the titanium-aluminum alloy powder with an aluminum content reaching a target aluminum content can be prepared, and the special needs of an electron beam additive manufacturing technology for high-aluminum-content titanium-aluminum alloy powder are met.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a method for preparing titanium-aluminum alloy powder for additive manufacturing. Background Art

[0002] Electron beam selective melting (EBSM), a rapidly developing additive manufacturing technology, offers unique advantages for preparing room-temperature brittle and difficult-to-machine materials. It provides a simple, rapid, and low-cost method for preparing TiAl intermetallic compounds. General Electric has successfully developed an EBSM process for preparing TiAl blades, and EBSM equipment is currently used primarily for the production of TiAl blades for low-pressure turbines in engines. However, the EBSM printing process of TiAl alloys results in aluminum losses of 1 to 2 at%, necessitating the preparation of TiAl powders with higher aluminum contents to compensate for these losses.

[0003] In the related art, there are three main ways to prepare titanium-aluminum powder with high aluminum content: 1. Prepare high aluminum content rods and use a gas atomization method to prepare titanium-aluminum powder with high aluminum content. When a gas atomization technology is used to prepare titanium-aluminum powder with high aluminum content, the prepared titanium-aluminum powder has a high oxygen content and more hollow powder. The quality of titanium-aluminum powder is crucial to the final performance of the product. The pores in the titanium-aluminum powder will reduce the creep and fatigue properties of the product and reduce the plasticity of the TiAl product. Excessive content of interstitial elements such as oxygen in the titanium-aluminum powder will increase the brittleness of the alloy at room temperature and high temperature. Therefore, this type of titanium-aluminum powder with a high oxygen content and more hollow powder prepared by the gas atomization method is not the best choice for alloys with high powder quality requirements.

[0004] Second, patent application number 202210340484.9 uses pure aluminum rods and pure titanium powder in a plasma rotating electrode atomization process (PREP) to produce high-aluminum-content titanium-aluminum powder. The main drawbacks of this patent are: the pure aluminum rods are relatively soft, and the PREP centrifugal force cannot achieve very high rotational speeds, generally below 15,000 r / min, and is prone to flanging during the powdering process. Furthermore, the pure aluminum rods are lightweight, resulting in a coarse powder size during PREP. The pure titanium powder used is typically atomized powder or hydrogenated dehydrogenated titanium powder, which has a high oxygen content. These two shortcomings ultimately lead to three major drawbacks in the high-aluminum-content titanium-aluminum alloy powder produced using this method: first, the coarse powder size does not meet the powder requirements for electron beam additive manufacturing (EBAM). Second, the powder's high oxygen content means the aluminum powder produced cannot meet the stringent EBAM requirements for the oxygen content of titanium-aluminum powder. Third, the powder making method using pure element mixed reaction cannot guarantee that pure titanium and pure aluminum elements can react fully and evenly under the high cooling rate powder making condition of PREP.

[0005] 3. Prepare high-aluminum-content titanium-aluminum rods and directly prepare high-aluminum-content titanium-aluminum powder using PREP technology. When using PREP technology to directly prepare high-aluminum-content titanium-aluminum powder, the following major disadvantages exist: 1. As the aluminum content increases, the castability of the titanium-aluminum material deteriorates and its brittleness increases, making it extremely prone to fracture during the casting process, making rod preparation more difficult. Furthermore, the highly brittle rods are extremely prone to fracture during the PREP powder production process and cannot be operated at high speeds. 2. High-aluminum-content titanium-aluminum alloy rods are mostly peritectic solidification structures with coarse grains and natural structural segregation. On the one hand, due to structural segregation, the high-aluminum-content titanium-aluminum rods have different micro-region melting points during the PREP powder production process due to segregation. As a result, a considerable portion of the structure cannot be fully heated to the ideal atomization and crushing temperature during the actual powder production process, resulting in poor powder crushing and an overall ultra-coarse powder. On the other hand, the prepared powder has uneven composition and may not meet the powder quality requirements of the target technology.

[0006] Therefore, it is necessary to provide a new technical solution to improve one or more problems existing in the above solutions.

[0007] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0008] The application aims to provide a preparation method of a titanium-aluminum alloy powder for additive manufacturing, thereby at least partially overcoming one or more problems caused by limitations and defects of the related art.

[0009] The application provides a preparation method of a titanium-aluminum alloy powder for additive manufacturing.

[0010] A titanium-aluminum rod is prepared and processed to obtain a titanium-aluminum electrode rod, wherein the aluminum content in the titanium-aluminum rod is less than 46 at%.

[0011] The titanium-aluminum electrode rod is placed in an atomization chamber, and one end of the titanium-aluminum electrode rod is connected to a connecting rod, wherein one end of the connecting rod is connected to a driving motor.

[0012] The atomization chamber is vacuumized and inert gas is introduced.

[0013] The atomization process parameters are set to powderize the titanium-aluminum electrode rod.

[0014] During the powderization of the titanium-aluminum electrode rod, a first aluminum addition treatment is performed to obtain a first aluminum addition titanium-aluminum alloy powder, wherein the first aluminum addition treatment comprises the following steps.

[0015] During the powderization, first particle size aluminum powder is introduced into the molten pool end face of the titanium-aluminum electrode rod to compensate the aluminum content of the molten pool being atomized and damaged, or aluminum vapor is introduced into the atomization chamber to wrap the titanium-aluminum droplets and compensate the aluminum content of the titanium-aluminum droplets, wherein the particle size of the first particle size aluminum powder is less than 30 microns, and the particle size of the first aluminum addition titanium-aluminum alloy powder is 53-150 microns.

[0016] The first aluminum addition titanium-aluminum alloy powder is classified according to the particle size to obtain titanium-aluminum alloy powder in different particle size ranges.

[0017] If the aluminum content of the titanium-aluminum alloy powder in at least one particle size range is lower than the target aluminum content, the titanium-aluminum alloy powder in the particle size range and second particle size aluminum powder are subjected to mechanical ball milling treatment, and the titanium-aluminum alloy powder after the homogenization treatment is obtained by high-temperature furnace homogenization treatment, wherein the second particle size aluminum powder is nano aluminum powder.

[0018] If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment is still lower than the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is subjected to a second aluminum addition treatment, so that the aluminum content of the titanium-aluminum alloy powder after the second aluminum addition treatment reaches the target aluminum content.

[0019] In an embodiment of the present application, after the step of obtaining the titanium-aluminum alloy powder after homogenization, the following steps are included:

[0020] If the aluminum content of the titanium-aluminum alloy powder after homogenization treatment is higher than the target aluminum content, the titanium-aluminum alloy powder after homogenization treatment is sent into the atomization chamber for plasma flame re-melting and solidification treatment to make the aluminum content of the titanium-aluminum alloy powder reach the target aluminum content.

[0021] In an embodiment of the present application, the step of performing a secondary aluminum addition treatment on the titanium aluminum alloy powder after the homogenization treatment includes:

[0022] The titanium-aluminum alloy powder after homogenization treatment is sent into the atomization chamber, and the aluminum vapor is introduced to perform aluminum enrichment treatment to obtain the titanium-aluminum alloy powder after secondary aluminum enrichment; or, the titanium-aluminum alloy powder after homogenization treatment and the second particle size aluminum powder are mechanically ball milled and homogenized in a high-temperature furnace to obtain the titanium-aluminum alloy powder after secondary aluminum enrichment.

[0023] In the embodiments of the present application, the different particle size ranges are: 33-63 μm, 64-75 μm, 76-106 μm, 107-125 μm and 126-150 μm.

[0024] In an embodiment of the present application, when aluminum powder with the first particle size is introduced into the end face of the molten pool of the titanium-aluminum electrode rod, the powder feeding rate is 0.01-2 g / s, and the powder feeding pressure is greater than 0.2 MPa.

[0025] In the embodiment of the present application, during the homogenization treatment in a high-temperature furnace, the heating temperature is 800-1300° C., and the insulation reaction diffusion time is 5-30 minutes.

[0026] In an embodiment of the present application, after the step of obtaining the titanium-aluminum alloy powder after homogenization, the following steps are included:

[0027] If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment reaches the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is judged as qualified powder and is packaged and stored.

[0028] In an embodiment of the present application, the atomization powder making process parameters include rotational speed, current and feed rate; wherein, the rotational speed is 24000-30000 rpm, the current is 1000-1500 A, and the feed rate is 0.8-1.5 mm / s.

[0029] In an embodiment of the present application, the diameter of the titanium-aluminum electrode rod is 50-70 mm, and the length of the titanium-aluminum electrode rod is 260-450 mm.

[0030] In the embodiment of the present application, the flow rate of the aluminum vapor is 0.1-3 m / s.

[0031] The technical solutions provided by the embodiments of the present application may have the following beneficial effects:

[0032] In one embodiment of the present application, through the above method, on the one hand, the present application uses a titanium aluminum bar with an aluminum content of less than 46at% for PREP powder making, and adopts two aluminum addition treatments, so that a titanium aluminum alloy powder with an aluminum content reaching the target aluminum content can be prepared, meeting the special requirements of electron beam additive manufacturing technology for high aluminum content titanium aluminum alloy powder. On the other hand, the present application adopts PREP technology to prepare titanium aluminum alloy powder, so that the oxygen content and hollow powder content of the powder can be controlled, and the powder quality is better than that using atomization technology. Titanium aluminum bars with an aluminum content of less than 46at% have good castability, few defects, and low brittleness. They can be powdered at a higher speed during the PREP powder making process and are not prone to breakage. In addition, the low aluminum content titanium aluminum bar has better composition uniformity due to the solidification path. The powder is easier to break into particles with a finer particle size during the PREP process, and the composition of the single powder is more uniform.

[0033] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0035] Figure 1 A flowchart schematically illustrates the steps of a method for preparing titanium-aluminum alloy powder for additive manufacturing in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0036] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0037] This exemplary embodiment provides a method for preparing titanium aluminum alloy powder for additive manufacturing. Figure 1As shown in , the method may include: steps S101 to S108.

[0038] Wherein, step S101: prepare titanium aluminum rod material, and process the titanium aluminum rod material to obtain titanium aluminum electrode rod material; wherein, the aluminum content in the titanium aluminum rod material is less than 46at%.

[0039] Step S102: placing a titanium-aluminum electrode rod into the atomization chamber, and connecting one end of the titanium-aluminum electrode rod to a connecting rod; wherein one end of the connecting rod is connected to a driving motor.

[0040] Step S103: vacuuming the atomization chamber and introducing inert gas.

[0041] Step S104: setting atomization powder making process parameters to powder the titanium aluminum electrode rod.

[0042] Step S105: During the powdering process of the titanium-aluminum electrode rod material, a primary aluminum addition process is performed to obtain a titanium-aluminum alloy powder after the primary aluminum addition process. The primary aluminum addition process includes:

[0043] During the powder making process, aluminum powder of the first particle size is introduced into the end face of the molten pool of the titanium-aluminum electrode rod material so that the aluminum powder of the first particle size can compensate for the aluminum content of the molten pool that is being atomized and damaged; or, aluminum vapor is introduced into the atomization chamber so that the aluminum vapor wraps the titanium-aluminum droplets and compensates for the aluminum content of the titanium-aluminum droplets; wherein the particle size of the first particle size aluminum powder is less than 30μm, and the particle size of the titanium-aluminum alloy powder after one aluminum addition is 53-150μm.

[0044] Step S106: Classifying the titanium-aluminum alloy powder after the primary aluminum addition according to the particle size to obtain titanium-aluminum alloy powders of different particle size ranges.

[0045] Step S107: If the aluminum content of the titanium-aluminum alloy powder in at least one particle size range is lower than the target aluminum content, the titanium-aluminum alloy powder in the particle size range and the second particle size aluminum powder are mechanically ball milled and homogenized in a high-temperature furnace to obtain the homogenized titanium-aluminum alloy powder; wherein the second particle size aluminum powder is nano-scale aluminum powder.

[0046] Step S108: If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment is still lower than the target aluminum content, a secondary aluminum enrichment treatment is performed on the titanium-aluminum alloy powder after the homogenization treatment to make the aluminum content of the titanium-aluminum alloy powder after the secondary aluminum enrichment reach the target aluminum content.

[0047] In one embodiment of the present application, through the above method, on the one hand, the present application uses a titanium aluminum bar with an aluminum content of less than 46at% for PREP powder making, and adopts two aluminum addition treatments, so that a titanium aluminum alloy powder with an aluminum content reaching the target aluminum content can be prepared, meeting the special requirements of electron beam additive manufacturing technology for high aluminum content titanium aluminum alloy powder. On the other hand, the present application adopts PREP technology to prepare titanium aluminum alloy powder, so that the oxygen content and hollow powder content of the powder can be controlled, and the powder quality is better than that using atomization technology. Titanium aluminum bars with an aluminum content of less than 46at% have good castability, few defects, and low brittleness. They can be powdered at a higher speed during the PREP powder making process and are not prone to breakage. In addition, the low aluminum content titanium aluminum bar has better composition uniformity due to the solidification path. The powder is easier to break into particles with a finer particle size during the PREP process, and the composition of the single powder is more uniform.

[0048] Below, we will refer to Figure 1 Each step of the above method in this exemplary embodiment is described in more detail.

[0049] In step S101, a titanium-aluminum bar is prepared and processed to obtain a titanium-aluminum electrode bar; wherein the aluminum content in the titanium-aluminum bar is less than 46 at %.

[0050] It's understandable that titanium-aluminum bars with an aluminum content of less than 46 at% are referred to as low-aluminum-content titanium-aluminum bars. These bars are produced through a process involving secondary consumable melting, primary induction melting, and centrifugal casting. The following process parameters are involved: a centrifugal speed of 50-300 rpm, a single-layer wall thickness of 15 mm or greater for the casting mold, a holding temperature of 500-1350°C, and a holding time of 0.5-1 hour.

[0051] It should be noted that at% represents atomic percentage. The secondary consumable melting, primary induction melting technology melting and centrifugal casting processes can all be understood with reference to the prior art, and this application will not elaborate on them.

[0052] The purpose of processing the titanium aluminum bar is to process the titanium aluminum bar to a target size, thereby obtaining a titanium aluminum electrode bar.

[0053] Furthermore, the target size is: the diameter of the titanium aluminum electrode bar is 50-70 mm, and the length of the titanium aluminum electrode bar is 260-450 mm. Titanium aluminum electrode bar within the target size range is easy to be pulverized using PREP.

[0054] In step S102, a titanium-aluminum electrode rod is placed in an atomization chamber, and one end of the titanium-aluminum electrode rod is connected to a connecting rod; wherein one end of the connecting rod is connected to a driving motor.

[0055] It can be understood that one end of the titanium-aluminum electrode bar is processed with a thread to facilitate connection with the connecting rod. When the titanium-aluminum electrode bar is connected with the connecting rod, the end surface of the titanium-aluminum electrode bar and the connecting rod is required to be attached with a degree of more than 90%, and the end of the titanium-aluminum electrode bar away from the connecting rod has a rotational runout of less than 15 wires after installation.

[0056] In step S103, the atomization chamber is vacuumized and inert gas is introduced.

[0057] Further, the atomization chamber is vacuumized to 5*10 -3 Pa, and then filled with inert gas to 0.05-0.1 Mpa. The vacuumization and inert gas introduction of the atomization chamber are mainly to provide a powder production environment and ensure smooth subsequent powder production. The inert gas can be argon.

[0058] In step S104, the atomization powder production process parameters are set to produce the titanium-aluminum electrode bar.

[0059] Further, the atomization powder production process parameters include rotational speed, current and feed rate; wherein the rotational speed is 24000-30000 rpm, the current is 1000-1500 A, and the feed rate is 0.8-1.5 mm / s.

[0060] It can be understood that before the titanium-aluminum electrode bar is produced by PREP, the atomization powder production process parameters are set to ensure that the titanium-aluminum electrode bar is smoothly produced by PREP.

[0061] In step S105, during the production of the titanium-aluminum electrode bar, a first aluminum increasing treatment is performed to obtain a first aluminum-increased titanium-aluminum alloy powder; wherein the first aluminum-increased treatment includes:

[0062] During the production, the first particle size aluminum powder is introduced into the molten pool end surface of the titanium-aluminum electrode bar to compensate the aluminum content of the molten pool being broken by atomization; or, aluminum vapor is introduced into the atomization chamber to wrap the titanium-aluminum liquid droplets and compensate the aluminum content of the titanium-aluminum liquid droplets; wherein the particle size of the first particle size aluminum powder is less than 30 μm, and the particle size of the first aluminum-increased titanium-aluminum alloy powder is 53-150 μm.

[0063] It can be understood that the first aluminum-increased treatment during the production of the titanium-aluminum electrode bar can increase the aluminum content in the titanium-aluminum alloy powder. The first aluminum-increased treatment mainly involves introducing the first particle size aluminum powder into the molten pool end surface of the titanium-aluminum electrode bar, or introducing aluminum vapor into the atomization chamber.

[0064] When the first-size aluminum powder is introduced into the end face of the molten pool of the titanium-aluminum electrode rod, the particle size of the first-size aluminum powder is required to be less than 30μm, the powder feeding rate is 0.01-2g / s, and the powder feeding pressure is greater than 0.2Mpa to ensure that the first-size aluminum powder is fully melted and reacted in a short time.

[0065] It should be noted that the first particle size aluminum powder can be introduced through the powder feeding pipe, the powder feeding pipe is arranged above the plasma gun, and the horizontal angle between the powder feeding pipe and the titanium aluminum electrode rod is 15°-60°. The horizontal angle between the powder feeding pipe and the titanium aluminum electrode rod can be adjusted within the range of 15° to 60°.

[0066] The theoretical feed rate of first-particle aluminum powder is related to the amount of aluminum added. For every planned 1at% aluminum addition, the required amount of aluminum added should be no less than 1.3% of the melted mass of the titanium-aluminum electrode bar per unit time. Considering that first-particle aluminum powder is easily affected by the flow field in the atomizing chamber and that the first-particle aluminum powder must cover the entire titanium-aluminum electrode bar melt pool during actual powder feeding, the straight-line distance between the powder feeding port of the powder feeding tube and the titanium-aluminum electrode bar melt pool should be no more than 60mm. The powder flow rate of the first-particle aluminum powder should be greater than 10m / s and less than 20m / s (excessive powder flow rate will disturb the plasma arc and melt pool, affecting quality stability). The inner diameter of the powder feeding tube is set to 2-10mm based on the powder feeding amount. The powder feeding port of the powder feeding tube is trumpet-shaped to ensure that the delivered first-particle aluminum powder is evenly spread across the entire end face of the titanium-aluminum electrode bar.

[0067] When aluminum vapor is introduced into the atomizing chamber, it is primarily introduced along a pipe surrounding the titanium-aluminum electrode rod. This allows the vapor to envelop the atomized titanium-aluminum droplets, compensating for the aluminum content and increasing the aluminum content in the titanium-aluminum alloy powder. The gap between the pipe and the titanium-aluminum electrode rod is 1-5 mm. Within this gap, the aluminum vapor can enter the atomizing chamber smoothly.

[0068] It should be noted that the pipe material is zirconium dioxide or pure tungsten to ensure that it can withstand the high temperature of aluminum at 2200°C.

[0069] Furthermore, the flow rate of the aluminum vapor is 0.1-3 m / s. Within this flow rate range, it is easy to smoothly introduce the aluminum vapor into the atomizing chamber.

[0070] The amount of aluminum added by introducing aluminum vapor into the atomizing chamber is limited, and the maximum amount of aluminum added is 1at%. The flow rate of aluminum vapor is 1-100L / s, and the flow rate of aluminum vapor can be adjusted according to actual conditions.

[0071] In step S106, the titanium-aluminum alloy powder after the primary aluminum addition is classified according to the particle size to obtain titanium-aluminum alloy powders of different particle size ranges.

[0072] Understandably, for electron beam 3D printing, the particle size of titanium-aluminum alloy powder is 53-150μm, a relatively large range. In the actual aluminum addition process, the amount of aluminum added to powders of different particle sizes will vary significantly, as smaller titanium-aluminum alloy powders have a larger specific surface area and therefore actually add more aluminum. Therefore, it is necessary to grade titanium-aluminum alloy powders according to particle size to facilitate subsequent testing of the aluminum content in titanium-aluminum alloy powders of different particle sizes.

[0073] Furthermore, the different particle size ranges are: 33-63μm, 64-75μm, 76-106μm, 107-125μm and 126-150μm.

[0074] It can be understood that by dividing the titanium-aluminum alloy powder into the above five different particle size intervals, it is convenient to detect the aluminum content in the titanium-aluminum alloy powder in different particle size intervals.

[0075] In step S107, if the aluminum content of the titanium-aluminum alloy powder in at least one particle size range is lower than the target aluminum content, the titanium-aluminum alloy powder in the particle size range and the second particle size aluminum powder are mechanically ball milled and homogenized in a high-temperature furnace to obtain the homogenized titanium-aluminum alloy powder; wherein the second particle size aluminum powder is nano-scale aluminum powder.

[0076] It is understandable that after obtaining the above-mentioned five different particle size intervals, the aluminum content in the titanium-aluminum alloy powder in each particle size interval is detected respectively. If the aluminum content of the titanium-aluminum alloy powder in at least one particle size interval is lower than the target aluminum content, this part of the titanium-aluminum alloy powder is mechanically ball-milled with the second particle size aluminum powder to mix and evenly coat this part of the titanium-aluminum alloy powder with the second particle size aluminum powder. The mixed powder after mechanical ball milling is then passed into a high-temperature furnace for heating reaction, and the aluminum element adsorbed on the surface of the titanium-aluminum alloy powder is evenly diffused to obtain the titanium-aluminum alloy powder after homogenization treatment. Among them, the second particle size aluminum powder is nano-scale aluminum powder. During the mechanical ball milling treatment, the nano-scale aluminum powder can ensure that the aluminum element is evenly adsorbed on the surface of the titanium-aluminum alloy powder.

[0077] It should be noted that the purpose of the homogenization treatment in a high-temperature furnace is to diffuse the aluminum element adsorbed on the surface of the titanium-aluminum alloy powder evenly, so as to obtain a titanium-aluminum alloy powder with a uniform distribution of the aluminum element.

[0078] Furthermore, during the homogenization process in a high-temperature furnace, the heating temperature is 800-1300° C., and the insulation reaction diffusion time is 5-30 minutes.

[0079] It can be understood that, in the process of homogenization treatment by the high-temperature furnace, the heating temperature of the high-temperature furnace is set to 800-1300℃, and the holding reaction diffusion time is set to 5-30min, so that the aluminum element adsorbed on the surface of the titanium-aluminum alloy powder can be uniformly diffused, and the titanium-aluminum alloy powder with uniform aluminum element distribution can be obtained.

[0080] In one embodiment, after the step of obtaining the homogenization-treated titanium-aluminum alloy powder, the following steps are included:

[0081] If the aluminum content of the homogenization-treated titanium-aluminum alloy powder is higher than the target aluminum content, the homogenization-treated titanium-aluminum alloy powder is sent into the atomization chamber for plasma flame remelting and solidification treatment, so that the aluminum content of the titanium-aluminum alloy powder reaches the target aluminum content.

[0082] It can be understood that, after obtaining the homogenization-treated titanium-aluminum alloy powder, if the aluminum content of the homogenization-treated titanium-aluminum alloy powder is higher than the target aluminum content, the homogenization-treated titanium-aluminum alloy powder needs to be treated so that the aluminum content of the titanium-aluminum alloy powder reaches the target aluminum content.

[0083] When the homogenization-treated titanium-aluminum alloy powder needs to be treated, the homogenization-treated titanium-aluminum alloy powder is mainly sent into the atomization chamber for plasma flame remelting and solidification treatment, which not only makes the element distribution in the titanium-aluminum alloy powder more uniform, but also makes the aluminum element burn out to reduce the aluminum content in the titanium-aluminum alloy powder, so that the aluminum content of the titanium-aluminum alloy powder reaches the target aluminum content.

[0084] It should be noted that, when the aluminum element in the titanium-aluminum alloy powder is burned out, the size of the aluminum element burnout in the titanium-aluminum alloy powder can be adjusted by adjusting the plasma flame power and the atomization chamber gas pressure. The plasma flame power is 20-150kW, and the atomization chamber gas pressure is 0.01-0.04Mpa.

[0085] In step S108, if the aluminum content of the homogenization-treated titanium-aluminum alloy powder is still lower than the target aluminum content, the homogenization-treated titanium-aluminum alloy powder is subjected to secondary aluminum addition treatment, so that the aluminum content of the titanium-aluminum alloy powder after secondary aluminum addition reaches the target aluminum content.

[0086] It can be understood that, if the aluminum content of the homogenization-treated titanium-aluminum alloy powder is still lower than the target aluminum content, the homogenization-treated titanium-aluminum alloy powder needs to be subjected to secondary aluminum addition treatment.

[0087] Further, in the step of subjecting the homogenization-treated titanium-aluminum alloy powder to secondary aluminum addition treatment, the following steps are included:

[0088] The titanium-aluminum alloy powder after homogenization treatment is sent into an atomization chamber, and aluminum vapor is introduced to perform aluminum enrichment treatment to obtain titanium-aluminum alloy powder after secondary aluminum enrichment; alternatively, the titanium-aluminum alloy powder after homogenization treatment and the second particle size aluminum powder are mechanically ball milled and homogenized in a high-temperature furnace to obtain titanium-aluminum alloy powder after secondary aluminum enrichment.

[0089] It is understandable that during the secondary aluminum addition treatment, the titanium-aluminum alloy powder after homogenization treatment is fed into the atomization chamber, and the powder feeding electrode rod is a high-purity tungsten rod or a high-purity copper rod. The internal interlayer of the high-purity tungsten rod or the high-purity copper rod is provided with a water channel for real-time cooling. The purpose is to ensure that the powder feeding electrode rod does not melt when the plasma flame acts on the end face of the powder feeding electrode rod, and the powder feeding electrode rod only plays a role in conducting a circuit. The rotation speed of the powder feeding electrode rod is 500-2000rpm. The rotation speed of the powder feeding electrode rod is set to a lower speed of 500-2000rpm. The purpose is to rotate the powder feeding electrode rod to ensure that the fed powder can be dispersed in time after passing through the high-temperature plasma flame, and to avoid adhesion between powders or powder adhesion to the end face of the powder feeding electrode rod. In addition, the rotation speed of the powder feeding electrode rod is low, and its centrifugal force is also low. The lower centrifugal force can maximize the stability of the airflow in the atomization chamber and reduce the difficulty of process control.

[0090] It should be noted that the method for introducing aluminum vapor during the secondary aluminum addition process is the same as the method for introducing aluminum vapor during the primary aluminum addition process in the above embodiment. The difference lies in the different powder feeding electrode rods. As mentioned above, during the secondary aluminum addition process, powder feeding electrode rods are not required to participate in the reaction. Therefore, high-purity tungsten rods or high-purity copper rods are used as powder feeding electrode rods, and water channels are provided in the inner interlayer of the high-purity tungsten rods or high-purity copper rods. During the primary aluminum addition process, powder feeding electrode rods are required to participate in the reaction. Therefore, titanium aluminum electrode rods are used as powder feeding electrode rods.

[0091] In addition, the method of mechanically ball milling the homogenized titanium aluminum alloy powder and the second particle size aluminum powder and homogenizing them in a high-temperature furnace to increase aluminum can be understood by referring to the above step S107, and this application will not elaborate on this.

[0092] In one embodiment, after the step of obtaining the homogenized titanium aluminum alloy powder, the following steps are included:

[0093] If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment reaches the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is judged as qualified powder and is packaged and stored.

[0094] It is understandable that after obtaining the titanium-aluminum alloy powder after homogenization treatment, if the aluminum content of the titanium-aluminum alloy powder after homogenization treatment reaches the target aluminum content, the titanium-aluminum alloy powder after homogenization treatment is determined to be qualified powder and packaged for storage.

[0095] It should be noted that in this application, an aluminum content greater than or equal to 46 at% is generally referred to as a high aluminum content, and the high aluminum content is the target aluminum content. The specific setting can be based on actual conditions, and this application will not elaborate on this.

[0096] The present application will be further described below through examples.

[0097] Example 1:

[0098] (1) Prepare titanium aluminum rods and process them to obtain titanium aluminum electrode rods. The titanium aluminum rods are Ti45Al8Nb, the diameter of the titanium aluminum electrode rods is 50 mm, and the target aluminum content is 47 at%, that is, to prepare Ti47Al8Nb powder, the aluminum content needs to be increased by 2 at%.

[0099] (2) Place the titanium-aluminum electrode rod into the atomizing chamber, and connect one end of the titanium-aluminum electrode rod to the connecting rod; wherein one end of the connecting rod is connected to the driving motor.

[0100] (3) Evacuate the atomization chamber to 5×10 -3 Pa, and then filled with high-purity argon gas to 0.05-0.1Mpa.

[0101] (4) Set the atomization powder making process parameters. The rotation speed of the titanium aluminum electrode bar is 20000r / min, the current is 1300A, and the feed rate is 1.2mm / s.

[0102] (5) During the powdering process of the titanium-aluminum electrode rod material, an aluminum enrichment treatment is performed to obtain titanium-aluminum alloy powder after the first aluminum enrichment.

[0103] The primary aluminum addition treatment includes: introducing aluminum powder of the first particle size into the end face of the molten pool of the titanium-aluminum electrode rod or introducing aluminum vapor into the atomization chamber.

[0104] When the first particle size aluminum powder is introduced: the powder feeding rate of the first particle size aluminum powder matches the melting rate of the titanium aluminum electrode rod. The powder feeding rate is set to 0.4g / s, the powder feeding air pressure is 2Mpa, and the powder flow rate of the first particle size aluminum powder is less than 20m / s. Setting a powder flow rate of less than 20m / s can prevent large disturbances to the molten pool. The particle size of the first particle size aluminum powder is 20μm. Setting a particle size of 20μm, on the one hand, facilitates the subsequent screening and separation of unreacted first particle size aluminum powder and titanium aluminum alloy powder. On the other hand, the finer first particle size aluminum powder can ensure that the first particle size aluminum powder is fully melted and reacted in a short time.

[0105] When aluminum vapor is introduced, it is piped along the outside of the titanium-aluminum electrode bar into the atomizing chamber, allowing the vapor to envelop the atomized titanium-aluminum droplets and compensate for the aluminum content. The gap between the pipe and the titanium-aluminum alloy bar is 3mm, the vapor velocity is 2m / s, the aluminum addition is 1at%, and the vapor flow rate is 30L / s.

[0106] (6) The titanium-aluminum alloy powder with a particle size of 53-150 μm was graded into five particle size intervals of 53-63 μm, 63-75 μm, 75-106 μm, 106-125 μm and 125-150 μm, and the aluminum content in the titanium-aluminum alloy powder in each particle size interval was detected.

[0107] (7) For titanium-aluminum alloy powder within a particle size range where the aluminum content is lower than the target aluminum content, this portion of the titanium-aluminum alloy powder is mechanically ball-milled with aluminum powder of a second particle size, and then homogenized in a high-temperature furnace to obtain a homogenized titanium-aluminum alloy powder. The aluminum powder of the second particle size is nano-sized aluminum powder.

[0108] (8) If the aluminum content of the titanium-aluminum alloy powder after homogenization treatment is higher than the target aluminum content, the titanium-aluminum alloy powder after homogenization treatment is fed into the atomization chamber through a plasma gun (a central powder feeding plasma gun with a hole punched in the middle of the powder feeding electrode rod that does not participate in the reaction). The pressure in the atomization chamber is adjusted to 0.02-0.03 MPa, and the titanium-aluminum alloy powder after homogenization treatment is re-melted and solidified to evaporate the aluminum element.

[0109] (9) If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment is still lower than the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is subjected to a secondary aluminum addition treatment so that the aluminum content of the titanium-aluminum alloy powder after the secondary aluminum addition reaches the target aluminum content, that is, the aluminum content of the titanium-aluminum alloy powder after the secondary aluminum addition is between 47±0.1at%.

[0110] The secondary aluminum enrichment treatment includes sending the titanium aluminum alloy powder after homogenization treatment into the atomization chamber and introducing aluminum vapor for aluminum enrichment treatment; or, mechanically ball milling the titanium aluminum alloy powder after homogenization treatment and the second particle size aluminum powder, and then homogenizing it in a high-temperature furnace.

[0111] When the homogenized titanium-aluminum alloy powder is introduced into the atomization chamber and aluminum vapor is introduced for aluminum enrichment, the powder is primarily fed into the atomization chamber via a powder feeding electrode rod. The feeder rod rotates at a speed of 500-2000 rpm, and the pressure within the atomization chamber is adjusted to 0.1-0.2 MPa to prevent aluminum volatilization. The aluminum vapor introduction method for the secondary aluminum enrichment treatment is the same as that for the primary aluminum enrichment treatment.

[0112] When the titanium-aluminum alloy powder after homogenization treatment and the second particle size aluminum powder are subjected to mechanical ball milling treatment, and are subjected to homogenization treatment through a high-temperature furnace, the heating temperature is 800-1300℃, and the holding reaction diffusion time is 5-30min, so that the aluminum element adsorbed on the surface of the titanium-aluminum alloy powder is uniformly diffused.

[0113] By the method provided in the application, the yield of the Ti47Al8Nb powder prepared from the Ti45Al8Nb bar material and having a particle size less than 150μm can reach 91.5%, and the aluminum content of the Ti47Al8Nb powder is between 47±0.1at%. However, the yield of the Ti47Al8Nb powder prepared from the Ti47A8Nb bar material by directly using the conventional plasma rotating electrode atomization powdering method and having a particle size less than 150μm is only 56%. Moreover, due to the element segregation of the Ti47Al8Nb bar material, the aluminum content of the Ti47Al8Nb powder having a particle size less than 150μm is 47.2at%, which is higher than the target aluminum content 47at%.

[0114] Embodiment 2:

[0115] (1) A titanium-aluminum bar material is prepared, and the titanium-aluminum bar material is processed to obtain a titanium-aluminum electrode bar material. The titanium-aluminum bar material is Ti45Al2cr2Nb, the diameter of the titanium-aluminum electrode bar material is 50mm, and the target aluminum content is 49at%, i.e., the Ti49Al2cr2Nb powder is prepared, and the aluminum increment required is 4at%.

[0116] (2) The titanium-aluminum electrode bar material is placed in an atomization chamber, and one end of the titanium-aluminum electrode bar material is connected with a connecting rod; one end of the connecting rod is connected with a driving motor.

[0117] (3) The atomization chamber is vacuumed to 5×10 -3 Pa, and then high-purity argon is filled to 0.05-0.1Mpa.

[0118] (4) The atomization powdering process parameters are set. The rotating speed of the titanium-aluminum electrode bar material is 28000r / min, the current is 1300A, and the feeding rate is 1.2mm / s.

[0119] (5) During the powdering process of the titanium-aluminum electrode bar material, a first aluminum increment treatment is performed to obtain a titanium-aluminum alloy powder after the first aluminum increment treatment.

[0120] The first aluminum increment treatment includes: introducing a first particle size aluminum powder into the molten pool end face of the titanium-aluminum electrode bar material or introducing aluminum vapor into the atomization chamber.

[0121] When the first particle size aluminum powder is introduced: the feeding rate of the first particle size aluminum powder is matched with the melting rate of the titanium-aluminum electrode rod. The feeding rate is set to 0.8 g / s, the powder feeding gas pressure is 2 MPa, and the powder flow rate of the first particle size aluminum powder is less than 20 m / s. The powder flow rate is set to less than 20 m / s to prevent large disturbance to the molten pool. The particle size of the first particle size aluminum powder is 20 μm, which is set to facilitate subsequent screening separation of the unreacted first particle size aluminum powder from the titanium-aluminum alloy powder. On the other hand, the fine first particle size aluminum powder can ensure that the first particle size aluminum powder is fully melted and reacted in a short time.

[0122] When the aluminum vapor is introduced: the pipeline along the outside of the titanium-aluminum electrode rod is used to introduce aluminum vapor into the atomization chamber to wrap the atomized titanium-aluminum liquid droplets with aluminum vapor, thereby achieving aluminum content compensation. The gap between the pipeline and the titanium-aluminum alloy rod is 5 mm, the flow rate of the aluminum vapor is 3 m / s, the aluminum content is 1 at%, and the flow rate of the aluminum vapor is 50 L / s.

[0123] (6) The titanium-aluminum alloy powder with a particle size of 53-150 μm is classified into five particle size intervals, i.e., 53-63 μm, 63-75 μm, 75-106 μm, 106-125 μm, and 125-150 μm, and the aluminum content in the titanium-aluminum alloy powder in each particle size interval is detected.

[0124] (7) For the titanium-aluminum alloy powder in the particle size interval with an aluminum content lower than the target aluminum content, the titanium-aluminum alloy powder is subjected to mechanical ball milling treatment with the second particle size aluminum powder, and is subjected to homogenization treatment in a high-temperature furnace to obtain the homogenized titanium-aluminum alloy powder. The second particle size aluminum powder is nano aluminum powder.

[0125] (8) If the aluminum content of the homogenized titanium-aluminum alloy powder is higher than the target aluminum content, the homogenized titanium-aluminum alloy powder is introduced into the atomization chamber through a plasma gun (central powder feeding plasma gun, the middle of the non-reactive powder feeding electrode rod is punched), the pressure in the atomization chamber is adjusted to 0.02-0.03 MPa, and the homogenized titanium-aluminum alloy powder is subjected to re-melting and solidification treatment to evaporate the aluminum element.

[0126] (9) If the aluminum content of the homogenized titanium-aluminum alloy powder is still lower than the target aluminum content, the homogenized titanium-aluminum alloy powder is subjected to secondary aluminum addition treatment to make the aluminum content of the titanium-aluminum alloy powder after secondary aluminum addition reach the target aluminum content, i.e., the aluminum content of the titanium-aluminum alloy powder after secondary aluminum addition is between 49±0.1 at%.

[0127] The secondary aluminum-increasing treatment includes sending the homogenized titanium-aluminum alloy powder into an atomization chamber and introducing aluminum vapor to increase the aluminum content; or mechanically ball-milling the homogenized titanium-aluminum alloy powder and second-size aluminum powder, and homogenizing the mixture in a high-temperature furnace.

[0128] When the homogenized titanium-aluminum alloy powder is sent into the atomization chamber and aluminum vapor is introduced to increase the aluminum content, the homogenized titanium-aluminum alloy powder is mainly sent into the atomization chamber by a powder feeding electrode rod. The rotation speed of the powder feeding electrode rod is 500-2000 rpm, and the pressure in the atomization chamber is adjusted to 0.1-0.2 Mpa to ensure that the aluminum element does not volatilize. The way of introducing aluminum vapor in the secondary aluminum-increasing treatment is the same as that in the primary aluminum-increasing treatment.

[0129] When the homogenized titanium-aluminum alloy powder is mechanically ball-milled with the second-size aluminum powder and homogenized in a high-temperature furnace, the heating temperature is 800-1300℃, and the holding reaction diffusion time is 5-30 min to realize the diffusion of the aluminum element adsorbed on the surface of the titanium-aluminum alloy powder.

[0130] By the method provided in the application, the yield of the Ti49Al2Cr2Nb powder prepared from the Ti45Al2Cr2Nb rod with a particle size less than 150 μm can reach 95.4%, and the aluminum content of the Ti49Al2Cr2Nb powder is between 49±0.1 at%. However, the yield of the Ti49Al2Cr2Nb powder prepared from the Ti49Al2Cr2Nb rod by the conventional plasma rotating electrode atomization method with a particle size less than 150 μm is only 43%. Moreover, due to the element segregation of the Ti49Al2Cr2Nb rod, the aluminum content of the Ti49Al2Cr2Nb powder with a particle size less than 150 μm is 48.5 at%, which is lower than the target aluminum content of 49 at%.

[0131] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

Claims

1. A method for preparing titanium aluminum alloy powder for additive manufacturing, characterized in that: The method includes: Preparing titanium aluminum rods and processing the titanium aluminum rods to obtain titanium aluminum electrode rods; wherein the aluminum content in the titanium aluminum rods is less than 46at%; The titanium-aluminum electrode rod is placed in the atomizing chamber, and one end of the titanium-aluminum electrode rod is connected to a connecting rod; wherein one end of the connecting rod is connected to a driving motor; The atomization chamber is vacuumed and an inert gas is introduced; Setting atomization powder making process parameters to powder the titanium aluminum electrode rod material; During the powdering process of the titanium-aluminum electrode rod material, an aluminum addition treatment is performed to obtain an aluminum-added titanium-aluminum alloy powder; wherein the aluminum addition treatment step comprises: During the powder making process, aluminum powder of a first particle size is introduced into the end face of the molten pool of the titanium-aluminum electrode rod material so that the aluminum powder of the first particle size compensates for the aluminum content of the molten pool that is being atomized and damaged; or aluminum vapor is introduced into the atomizing chamber so that the aluminum vapor envelops titanium-aluminum droplets and compensates for the aluminum content of the titanium-aluminum droplets; wherein the particle size of the aluminum powder of the first particle size is less than 30 μm, and the particle size of the titanium-aluminum alloy powder after the first aluminum addition is 53-150 μm; Classifying the titanium-aluminum alloy powder after the primary aluminum addition according to particle size to obtain titanium-aluminum alloy powders of different particle size ranges; If the aluminum content of the titanium-aluminum alloy powder in at least one particle size range is lower than the target aluminum content, the titanium-aluminum alloy powder in the particle size range is mechanically ball-milled with aluminum powder of a second particle size, and homogenized in a high-temperature furnace to obtain the titanium-aluminum alloy powder after homogenization; wherein the aluminum powder of the second particle size is nano-sized aluminum powder; If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment is still lower than the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is subjected to a secondary aluminum addition treatment so that the aluminum content of the titanium-aluminum alloy powder after the secondary aluminum addition reaches the target aluminum content.

2. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: After the step of obtaining the titanium-aluminum alloy powder after homogenization, the method further comprises: If the aluminum content of the titanium-aluminum alloy powder after homogenization treatment is higher than the target aluminum content, the titanium-aluminum alloy powder after homogenization treatment is sent into the atomization chamber for plasma flame re-melting and solidification treatment to make the aluminum content of the titanium-aluminum alloy powder reach the target aluminum content.

3. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The step of performing a secondary aluminum addition treatment on the titanium aluminum alloy powder after the homogenization treatment comprises: The titanium-aluminum alloy powder after homogenization treatment is sent into the atomization chamber, and the aluminum vapor is introduced to perform aluminum enrichment treatment to obtain the titanium-aluminum alloy powder after secondary aluminum enrichment; or, the titanium-aluminum alloy powder after homogenization treatment and the second particle size aluminum powder are mechanically ball milled and homogenized in a high-temperature furnace to obtain the titanium-aluminum alloy powder after secondary aluminum enrichment.

4. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The different particle size ranges are: 33-63μm, 64-75μm, 76-106μm, 107-125μm and 126-150μm.

5. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: When aluminum powder of the first particle size is introduced into the end face of the molten pool of the titanium-aluminum electrode bar, the powder feeding rate is 0.01-2 g / s, and the powder feeding pressure is greater than 0.2 MPa.

6. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: During the homogenization process in a high-temperature furnace, the heating temperature is 800-1300°C, and the insulation reaction diffusion time is 5-30 minutes.

7. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: After the step of obtaining the titanium-aluminum alloy powder after homogenization, the method further comprises: If the aluminum content of the titanium-aluminum alloy powder after the homogenization treatment reaches the target aluminum content, the titanium-aluminum alloy powder after the homogenization treatment is judged as qualified powder and is packaged and stored.

8. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The atomization powder making process parameters include rotation speed, current and feed rate; wherein, the rotation speed is 24000-30000rpm, the current is 1000-1500A, and the feed rate is 0.8-1.5mm / s.

9. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The diameter of the titanium-aluminum electrode rod is 50-70 mm, and the length of the titanium-aluminum electrode rod is 260-450 mm.

10. The method for preparing titanium-aluminum alloy powder for additive manufacturing according to claim 1, characterized in that: The flow rate of the aluminum vapor is 0.1-3 m / s.

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