Particle-reinforced high-entropy alloy spherical powder and preparation method and application thereof

Abstract

The invention provides particle reinforced high-entropy alloy spherical powder and a preparation method and application thereof. The particle strengthening high-entropy alloy spherical powder comprises the following components in percentage by weight: 10 to 40 percent of Nb, 10 to 40 percent of Mo, 10 to 40 percent of Ta and 0.5 to 10 percent of carbide particles. According to the method, the NbTaMoC series refractory high-entropy alloy is smelted through the combination of a hot isostatic pressing powder metallurgy method and an electron beam remelting method, an electrode bar large in size and uniform in component is obtained, and then the particle strengthening high-entropy alloy spherical powder is prepared through a plasma rotating electrode atomization method. The particle strengthening high-entropy alloy spherical powder is uniform in component, low in H, O and N impurity content, high in purity, good in sphericity rate, uniform and concentrated in particle size distribution and low in proportion of satellite balls and hollow powder, and is particularly suitable for being used as a powder raw material to be used in the field of subsequent powder bed additive manufacturing forming.

Description

Technical Field

[0001] The invention relates to alloy technology, and in particular to a particle-reinforced high-entropy alloy spherical powder, a preparation method and application thereof. Background Art

[0002] In recent years, high entropy alloys (HEAs) have become a hot topic in materials research due to their unique multi-principal element design concept and excellent performance. In 2010, Senkov's team developed a refractory high entropy alloy composed of high melting point metals such as W, Mo, Nb, Ta, V, Hf, and Zr in an equiatomic ratio or approximately equiatomic ratio. This type of high entropy alloy has high entropy effect, lattice distortion, hysteresis diffusion effect, and cocktail effect. It has high hardness and excellent high-temperature mechanical properties, which has attracted widespread attention in the field of materials science. It is reported that the NbMoTaW high entropy alloy prepared by the team has a compressive yield strength of 1058MPa and 405MPa at room temperature and 1600°C, respectively, showing excellent room temperature strength and high temperature mechanical properties (Mechanicalproperties of Nb 25 Mo 25 Ta 25 W 25 and V 20 Nb 20 Mo 20 Ta 20 W 20 refractory high entropy alloys[J].Intermetallics,2011,19(5):698-706.). Raman's team reported that the refractory high entropy alloy CrMoNbTiW has a high hardness of 8.9GPa. (Phase evolution of refractory high-entropy alloyCrMoNbTiW during mechanical alloying and spark plasma sintering[J].Journal ofMaterials Research,2019,34:756-766.))

[0003] In order to further improve the strength and hardness of refractory high entropy alloys, researchers have tried to introduce second phase particles, such as carbides, nitrides or oxides, into the high entropy alloy matrix. These high melting point particles have extremely high chemical stability and mechanical properties. The dispersion of these particles between grain boundaries not only inhibits grain growth, but also improves the strength and hardness of high entropy alloys through fine grain strengthening and particle strengthening mechanisms. As reported in the literature, in Mo 0.5 HkDJ 0.5The addition of carbide particles to ZrTi alloy significantly improves the compressive strength (Microstructure and mechanical properties of in-situ MC-carbide particulates-reinforced refractory high-entropyMo 0.5 HkDJ 0.5 ZrTi matrix alloy composite[J].Intermetallics,2016,69:74-77.).

[0004] Refractory high-entropy alloys and particle-reinforced refractory high-entropy alloys have obvious room temperature brittleness, and it is difficult to manufacture complex structural parts by casting and other methods, which greatly limits their scope of application. In comparison, powder bed additive manufacturing technology uses high-energy beams to melt metal powders and form them in a layer-by-layer stacking manner. It can be used to prepare parts with complex shapes and provides a good technical approach for the molding of structural parts containing high-melting point components. Spherical powder is an important raw material for powder bed additive manufacturing technology. The quality of the powder largely determines the final molding effect of the product. Therefore, high-quality spherical powder is crucial to powder bed additive forming technology. The preparation of particle-reinforced high-entropy alloy spherical powder is an important basic guarantee for the engineering application of refractory high-entropy alloys.

[0005] In the field of spherical powder preparation, vacuum induction gas atomization is a widely used method. Its basic principle is to melt the metal or alloy material through an induction heating device, then let the molten metal flow out through a nozzle, and use a high-speed gas flow to atomize the metal liquid into fine droplets. These droplets cool and solidify rapidly during flight to form spherical powders. At present, the use of vacuum induction gas atomization to prepare low-melting-point CoCrFeNiMn high-entropy alloy spherical powder powders [Patent Name: A ceramic particle reinforced high-entropy alloy composite coating and its preparation method, application / patent number: CN202410617089.X] and relatively high-melting-point titanium alloy spherical powders have been reported [Patent Name: A multi-stage gas atomization preparation method for titanium alloy spherical powders for 3D printing technology, application / patent number: CN202210086640.3], however, there are challenges in using vacuum induction gas atomization to prepare powders containing refractory metals (such as tungsten, molybdenum, hafnium, etc.). Refractory metals have extremely high melting points, which are beyond the effective operating temperature range of conventional vacuum induction gas atomization induction heating devices, resulting in the inability to completely melt in standard vacuum induction equipment. In addition, melting and atomizing refractory metals requires higher energy and high-temperature resistant materials to maintain the stability of the equipment, which makes the conventional vacuum induction gas atomization method unsuitable for preparing refractory high-entropy alloy and its composite spherical powders. Therefore, it is urgent to develop a new technology for preparing particle-reinforced high-entropy alloy spherical powders. Summary of the invention

[0006] The purpose of the present invention is to address the problem that a vacuum induction gas atomization method is not suitable for preparing spherical powders of refractory high entropy alloys and their composite materials, and to propose a particle-reinforced high entropy alloy spherical powder. The spherical powder is prepared by a plasma rotating electrode atomization method, has uniform composition, low H, O, and N impurity content, high purity, good sphericity, uniform and concentrated particle size distribution, and a low ratio of satellite spheres and hollow powders. The powder is particularly suitable as a powder raw material for use in the subsequent powder bed additive manufacturing forming field.

[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a particle-reinforced high-entropy alloy spherical powder, the components and contents of which are as follows:

[0009] Nb: 10~40at.%;

[0010] Mo: 10~40at.%;

[0011] Ta: 10~40at.%;

[0012] Carbide particles: 0.5-10wt.%.

[0013] Furthermore, the components and contents of the particle-reinforced high entropy alloy spherical powder are preferably as follows:

[0014] Nb: 20~40at.%;

[0015] Mo: 15-30 at.%;

[0016] Ta: 20~40at.%.

[0017] Carbide particles: 1-5wt.%.

[0018] Furthermore, the carbide particles are one or more of TaC, WC, ZrC and HfC.

[0019] Furthermore, the carbide particles are preferably TaC, and the preferred addition amount is 1.5 wt.%.

[0020] Furthermore, the particle size distribution range of the particle-reinforced high entropy alloy spherical powder is D 10＝ 25-40 μm, D 50＝ 45-60μm, D 90＝ 75-100μm.

[0021] Another object of the present invention is to disclose a method for preparing a particle-reinforced high entropy alloy spherical powder, comprising the following steps:

[0022] S1. Preparation of electrode rod ingot

[0023] Weigh each metal element powder and carbide particle powder in the particle-reinforced high-entropy alloy spherical powder according to the ratio, mix them and put them into a rubber sleeve, and obtain a cylindrical blank by cold isostatic pressing;

[0024] The cylindrical blank is vacuum-encapsulated in a tantalum alloy sheath, and a powder metallurgy cylindrical sample is obtained by hot isostatic pressing.

[0025] placing the powder metallurgy cylindrical sample into an electron beam vacuum melting furnace for electron beam melting to obtain a particle-reinforced refractory high entropy alloy ingot;

[0026] S2. Preparation of Rotating Electrode Alloy Rod

[0027] The particle-reinforced refractory high entropy alloy ingot is processed by a mechanical method to prepare a rotating electrode alloy rod;

[0028] S3. Rotating electrode atomization powder making

[0029] The rotating electrode alloy rod is loaded into the rotating electrode atomization powder making equipment, and after sealing, vacuum is drawn, and the rotating button is started. When the preset speed is reached, the plasma gun is started to prepare spherical powder;

[0030] S4. Obtain particle-reinforced high-entropy alloy spherical powders in different particle size ranges by sieve classification.

[0031] Furthermore, the average particle size of the metal element powder described in S1 is less than 80 μm.

[0032] Furthermore, the carbide particle powder described in S1 has a particle size of 1-10 μm.

[0033] Furthermore, the mixing in S1 adopts a V-type mixer, and the mixing time is 10-30 hours, preferably the mixing time is 20 hours.

[0034] Furthermore, the cold isostatic pressing in S1 adopts an oil press, and the hot isostatic pressing adopts a hot isostatic pressing sintering equipment.

[0035] Furthermore, the pressing intensity used in the cold isostatic pressing process of S1 is 100MPa to 500MPa, and the holding time is 5min to 30min.

[0036] Furthermore, the hot isostatic pressing in S1 has a pressure of 50 to 300 MPa, a temperature of 1300 to 2000° C., and a heat preservation time of 4 to 10 h.

[0037] Furthermore, the electron beam melting conditions described in S1 are: electron beam power of 100-260 kW, melting rate of 25-50 kg / h, and repeated remelting for 5 times or more.

[0038] Furthermore, the specifications of the rotating electrode alloy rod in S2 are: diameter 30mm-60mm, length 100-400mm, coaxiality based on the axis ≤0.05mm, and cross-sectional circular runout based on the axis ≤0.02mm.

[0039] Furthermore, S3 loads the rotating electrode alloy rod into the rotating electrode atomizing powder making equipment, seals and evacuates, then fills in argon as a protective gas, starts the rotation button, and when the preset speed is reached, starts the plasma gun to generate a high-temperature plasma arc between the rotating electrode alloy rod and the plasma gun. The end face of the rotating electrode alloy rod melts to form a metal liquid film under the heating action of the plasma beam; the metal liquid film ejects tiny spherical droplets under the combined action of centrifugal force and surface tension, and the spherical droplets quickly cool and solidify into spherical powder.

[0040] Furthermore, the purity of the argon gas in S3 is greater than or equal to 99.99%.

[0041] Furthermore, the vacuum in S3 is performed so that the pressure inside the device is less than 7×10 -3 Pa.

[0042] Furthermore, in S3, the distance between the rotating electrode alloy rod and the plasma gun is 5-15 mm, the feed speed is 0.5-2.0 mm / s, the preset rotation speed is 15000 r / min-40000 r / min, and the current intensity is 1300A-2000A.

[0043] The plasma rotating electrode atomization powder making equipment generally includes components such as a plasma heating system, a rod high-speed drive system, a water cooling system, a rod feeding system, a feeding system, a vacuum and gas circulation purification system, a powder collection system, and an automatic control system. The present invention feeds the obtained NbTaMoC rotating electrode alloy rod into the atomization chamber of the vertical plasma rotating electrode powder making equipment, and then evacuates the atomization chamber and fills it with high-purity argon gas for protection. The NbTaMoC rotating electrode alloy rod is melted into alloy droplets under the action of a transferred arc plasma gun, and the alloy droplets are centrifugally dispersed in the atomization chamber, and spherical refractory high entropy alloy powder is obtained after condensation.

[0044] In the plasma rotating electrode atomization process, the droplet breakup mechanism mainly relies on centrifugal force. The plasma rotating electrode atomization technology generates a strong centrifugal force through a high-speed rotating electrode, so that the liquid is quickly split into tiny droplets under the action of centrifugal force. This process is almost independent of the external gas environment, reducing the interference of the airflow on the droplet motion trajectory and breakup behavior. In the traditional gas atomization method, the gas flow rate and pressure play a decisive role in the breakup of the droplets, resulting in the droplets being affected by a greater aerodynamic force during the atomization process, thereby affecting the particle size distribution and morphology uniformity of the powder. Therefore, in the plasma rotating electrode atomization process, the droplets can be more evenly distributed during the atomization process, forming a more concentrated particle size distribution and a more regular morphology.

[0045] In the plasma rotating electrode atomization powder making process, the change in the thickness of the liquid film on the end surface of the rotating electrode causes the droplet breakup mechanism to present three different forms: direct droplet breakup, liquid line breakup, and liquid film breakup. Specifically, at low melting speeds, the liquid film is thinner, and regular spherical powders are generated through the direct droplet breakup mechanism; as the melting speed increases, the liquid film gradually thickens, and the liquid line breakup mechanism produces powders with a wide particle size distribution and some elliptical shapes; at higher melting speeds, the liquid film further thickens and becomes unstable, and irregular flakes and larger particles are formed through the liquid film breakup mechanism. The differences in liquid film thickness caused by process parameters such as rod rotation speed, melting speed, rod diameter, and distance between rod and arc lead to different breakup mechanisms, which significantly affect the particle size and distribution quality of the final powder.

[0046]

[0047] In the formula:

[0048] H is the determination coefficient

[0049] Q is the melting rate / m 3 ·s -1

[0050] μ is the dynamic viscosity coefficient Pa·s

[0051] ω is the angular velocity rad·s -1

[0052] γ is the surface tension coefficient J / m 2

[0053] D is the diameter of the electrode rod m

[0054] ρ is the density of the melt kg·m -3

[0055] When H < 0.07, direct droplet breakup is the main breakup mode; when 0.07 < H < 1.33, liquid line breakup is the main breakup mode; when H > 1.33, liquid line breakup is the main breakup mode.

[0056] Combined with the characteristics of the particle-reinforced high-entropy alloy of the present invention, the preferred process parameters are: the diameter of the electrode rod is 30 mm to 60 mm, the length is 100 to 400 mm, the coaxiality based on the axis is ≤ 0.05 mm, and the circular runout of the cross-section based on the axis is ≤ 0.02 mm. The distance between the plasma guns is 5 - 15 mm, the feeding speed is 0.5 - 2.0 mm / s, the preset rotational speed is 15000 r / min to 40000 r / min, and the current intensity is 1300 A to 2000 A. Through calculation and experiments, it is ensured that within the process parameter range of the present invention, the criterion value is between 0.07 < H < 1.33, meeting the conditions of the linear breakup mechanism, thus ensuring good powder sphericity, uniform particle size distribution, and few irregular powders. If the process parameters exceed the above process range, it will lead to the generation of irregular powders, thereby resulting in a decline in product quality.

[0057] Another object of the present invention also discloses the use of a particle-reinforced high-entropy alloy spherical powder in the field of powder bed additive manufacturing.

[0058] The purpose of the present invention is to provide a method for preparing high-hardness and high-temperature resistant particle-reinforced high-entropy alloy spherical powder. The powder microstructure is composed of a refractory high-entropy matrix and carbide particles, so it has high hardness and high-temperature resistance. At the same time, a method for preparing high-hardness and high-temperature resistant particle-reinforced high-entropy alloy spherical powder is provided, which effectively solves the technical problem of the difficulty in preparing high-melting point spherical powder. The alloy spherical powder prepared by the method has the characteristics of uniform composition, low H, N, and O impurity content, high purity, good sphericity, uniform and concentrated particle size distribution, and low proportion of satellite balls and hollow powders.

[0059] The particle-reinforced high-entropy alloy spherical powder, preparation method and use thereof of the present invention have the following advantages compared with the prior art:

[0060] 1) The preparation method of the particle-reinforced high-entropy alloy spherical powder of the present invention is scientific and reasonable. In the present invention, the refractory metal component and the carbide particles are uniformly mixed by ball milling according to the designed component ratio, and the alloy rod is prepared by cold pressing + hot isostatic pressing + electron beam melting method, and then the consumable electrode is prepared by a mechanical processing method. The high-speed rotating consumable electrode is heated and melted by a rotating electrode atomization powder making device under the action of a plasma beam. The liquid molten film formed by the heated and melted consumable electrode is ejected and crushed into small molten droplets under the action of centrifugal force. The ejected droplets are formed into a sphere under the action of surface tension and rapidly solidified in flight to form a spherical powder.

[0061] 2) The particle-reinforced high-entropy alloy spherical powder prepared by the present invention is composed of a refractory high-entropy alloy matrix and reinforced particles, wherein the high-entropy alloy matrix is ​​composed of Nb, Mo, and Ta as components, and the reinforced particles are carburized particles. The particle-reinforced high-entropy alloy spherical powder prepared by the present invention has uniform composition, low H, O, and N impurity content (O content 80-400ppm, H content less than 150ppm), high purity, good sphericity (sphericity>92%), uniform and concentrated particle size distribution, low proportion of satellite spheres and hollow powders (less than 1%), etc., and is particularly suitable as a powder raw material for subsequent powder bed additive manufacturing forming fields.

[0062] 3) The fluidity of the particle-reinforced high-entropy alloy spherical powder prepared by the present invention is detected by a Hall flowmeter. 50g of powder sample is weighed and the powder is allowed to flow smoothly into the container, and the flow time is recorded. The fluidity of the particle-reinforced high-entropy alloy spherical powder prepared by the present invention is 5-10s / 50g. The particle size of the particle-reinforced high-entropy alloy spherical powder prepared by the present invention is measured by a laser particle size analyzer. 10 , D 50 , D 90 Data and cumulative distribution of particle size. 10＝ 25-40 μm, D 50＝ 45-60μm, D90＝ 75-100μm;

[0063] 4) The particle-reinforced high-entropy alloy spherical powder of the present invention has very good application prospects and large-scale industrial promotion potential in the field of powder bed additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The Nb prepared in Example 1 40 Ta 40 Mo 20- 1.5wt.%TaC particles reinforced high entropy alloy ingot;

[0065] Figure 2 The Nb prepared in Example 1 40 Ta 40 Mo 20- 1.5wt.%TaC spherical powder morphology;

[0066] Figure 3 The Nb prepared in Example 1 40 Ta 40 Mo 20- 1.5wt.% TaC spherical powder particle size distribution diagram;

[0067] Figure 4 The Nb prepared in Example 1 40 Ta 40 Mo 20- Element distribution diagram of 1.5wt.% TaC spherical powder;

[0068] Figure 5 Nb prepared in Comparative Example 1 40 Ta 40 Mo 20- 1.5wt.%TaC spherical powder morphology. DETAILED DESCRIPTION

[0069] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0070] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0071] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0072] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0073] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0074] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0075] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0076] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0077] Example 1

[0078] This embodiment discloses a particle-reinforced high entropy alloy spherical powder, which contains the following components and contents: Nb: 40 at.%, Ta: 40 at.%, Mo: 20 at.%, and its corresponding chemical formula is Nb 40 Ta 40 Mo 20 According to the total weight of 10kg, the weight of Nb is 2.88kg, the weight of Ta is 5.62kg, and the weight of Mo is 1.50kg. The particle size of the metal powder used is less than 80μm. The carbide particles are TaC powder, and the particle size is 1-10μm. The added amount accounts for 1.5wt.% of the total weight, that is, the total amount of TaC powder added is 0.15kg.

[0079] The preparation method of the particle-reinforced high-entropy alloy spherical powder is as follows:

[0080] S1. Preparation of electrode rod ingot

[0081] The metal powder and carbide particle powder in the particle-reinforced high-entropy alloy spherical powder are weighed according to the ratio, mixed in a V-type mixer for 20 hours, and then loaded into a rubber sleeve, and cold isostatic pressing is used to obtain a cylindrical blank; the cold isostatic pressing is performed using an oil press. The pressing strength used in the cold isostatic pressing process is 150MPa, and the holding time is 20min.

[0082] The cylindrical blank is vacuum-encapsulated in a tantalum alloy sheath, and a powder metallurgy cylindrical sample is obtained by hot isostatic pressing, wherein the hot isostatic pressing adopts a hot isostatic pressing sintering device. The hot isostatic pressing is performed at a pressure of 140 MPa, a temperature of 1500° C., and a holding time of 6 hours.

[0083] The powder metallurgy cylindrical sample is placed in an electron beam vacuum melting furnace for electron beam melting to obtain a particle-reinforced refractory high-entropy alloy ingot; the electron beam melting conditions are: electron beam power range: 150 kW, melting rate: 30 kg / h, and repeated remelting for 5 times or more.

[0084] S2. Preparation of Rotating Electrode Alloy Rod

[0085] The particle-reinforced refractory high-entropy alloy ingot is used to prepare a rotating electrode alloy rod through a mechanical processing method; S2 The rotating electrode alloy rod has the following specifications: diameter 35mm, length 200mm, coaxiality based on the axis ≤0.05mm, and cross-sectional circular runout based on the axis ≤0.02mm.

[0086] S3. Rotating electrode atomization powder making

[0087] The rotating electrode alloy rod is placed in the rotating electrode atomizing powder making equipment, and the equipment is sealed and evacuated so that the pressure inside the equipment is less than 7×10 -3 Pa. Then, argon (purity of 99.99%) is filled as a protective gas, and the rotation button is started. When the preset rotation speed is reached, the plasma gun is started. The distance between the rotating electrode alloy rod and the plasma gun is 10 mm, the feed speed is 1.5 mm / s, the preset rotation speed is 35000 r / min, and the current intensity is 1400 A. A high-temperature plasma arc is generated between the rotating electrode alloy rod and the plasma gun. The end face of the rotating electrode alloy rod is melted to form a metal liquid film under the heating action of the plasma beam; the metal liquid film throws out tiny spherical droplets under the combined action of centrifugal force and surface tension, and the spherical droplets are quickly cooled and solidified into spherical powder.

[0088] S4. Obtain particle-reinforced high-entropy alloy spherical powders in different particle size ranges by sieve classification.

[0089] Figure 1 The Nb prepared in Example 1 40 Ta 40 Mo 20 -1.5wt.%TaC particles reinforced high entropy alloy ingot; Figure 2 The Nb prepared in Example 1 40 Ta 40 Mo 20 -1.5wt.%TaC spherical powder morphology; Figure 3 The Nb prepared in Example 1 40 Ta 40 Mo 20 -1.5wt.%TaC spherical powder particle size distribution diagram; Figure 4 The Nb prepared in Example 1 40 Ta 40 Mo 20-1.5wt.% TaC spherical powder element distribution diagram; It can be seen that the particle-reinforced high-entropy alloy powder prepared in Example 1 has excellent sphericity and surface morphology. The powder presents a nearly perfect sphere with a smooth surface and no obvious defects. At the same time, the components of the powder are evenly distributed, ensuring the consistency of the chemical composition of each particle, which can effectively guarantee the consistency and stability of subsequent processing and application. In addition, the powder particle size distribution is also relatively concentrated. After testing, the sphericity of the particle-reinforced high-entropy alloy spherical powder in this embodiment is 94%, the fluidity is 7.0 (s / 50g), the O content is 85ppm, the H content is 50ppm, and the particle size distribution is measured by Bettersize2600 laser particle size distribution instrument, D 10 =33.50μm, D 50 =52.40μm, D 90 =96.35μm. Suitable for applications requiring high precision and high quality powder, such as 3D printing, metal powder metallurgy and other fields.

[0090] Comparative Example 1

[0091] This embodiment discloses a particle-reinforced high entropy alloy spherical powder, which contains the following components and contents: Nb: 40 at.%, Ta: 40 at.%, Mo: 20 at.%, and its corresponding chemical formula is Nb 40 Ta 40 Mo 20 According to the total weight of 10kg, the weight of Nb is 2.88kg, the weight of Ta is 5.62kg, and the weight of Mo is 1.50kg. The particle size of the metal single substance powder used is less than 80μm. The carbide particles are TaC powder, and the particle size is 1-10μm. The added amount accounts for 1.5wt.% of the total weight, that is, the total amount of TaC powder added is 0.15kg.

[0092] S1. Preparation of electrode rod ingot

[0093] The metal element powders and carbide particle powders in the particle-reinforced high-entropy alloy spherical powder are weighed according to the ratio, mixed in a V-type mixer for 20 hours, and then loaded into a rubber sheath, and cold isostatic pressing is used to obtain a cylindrical blank; the cold isostatic pressing is carried out using an oil press, and the pressing strength used in the cold isostatic pressing process is 180 MPa, and the holding time is 30 minutes.

[0094] The cylindrical blank is vacuum-encapsulated in a tantalum alloy sheath, and a powder metallurgy cylindrical sample is obtained by hot isostatic pressing. The hot isostatic pressing adopts a hot isostatic pressing sintering equipment, and the hot isostatic pressing pressure is 160 MPa, the temperature is 1600° C., and the holding time is 8 hours.

[0095] The powder metallurgy cylindrical sample is placed in an electron beam vacuum melting furnace for electron beam melting to obtain a particle-reinforced refractory high-entropy alloy ingot; the electron beam melting conditions are: electron beam power range: 150 kW, melting rate: 35 kg / h, and repeated remelting for 5 times or more.

[0096] S2. Preparation of Rotating Electrode Alloy Rod

[0097] The particle-reinforced refractory high-entropy alloy ingot is mechanically processed to prepare a rotating electrode alloy rod; the rotating electrode alloy rod has the following specifications: diameter 30 mm, length 250 mm, coaxiality based on the axis ≤ 0.05 mm, and cross-sectional circular runout based on the axis ≤ 0.02 mm.

[0098] S3. Rotating electrode atomization powder making

[0099] The rotating electrode alloy rod is placed in the rotating electrode atomization powder making equipment, and the equipment is sealed and evacuated so that the pressure inside the equipment is less than 7×10 -3 Pa. Then, argon (purity of 99.99%) is filled as a protective gas, and the rotation button is started. When the preset rotation speed is reached, the plasma gun is started. The distance between the rotating electrode alloy rod and the plasma gun is 4 mm, the feed speed is 2.5 mm / s, the preset rotation speed is 13000 r / min, and the current intensity is 2200 A. A high-temperature plasma arc is generated between the rotating electrode alloy rod and the plasma gun. The end face of the rotating electrode alloy rod is melted to form a metal liquid film under the heating action of the plasma beam; the metal liquid film throws out tiny spherical droplets under the combined action of centrifugal force and surface tension, and the spherical droplets are quickly cooled and solidified into spherical powder.

[0100] S4. Obtain particle-reinforced high-entropy alloy spherical powders in different particle size ranges by sieve classification.

[0101] Figure 5 NNb prepared in Comparative Example 1 40 Ta 40 Mo 20 -1.5wt.% TaC-shaped powder morphology, it can be seen that a large amount of irregular powder appears in the powder, and the proportion of satellite sphere powder also increases. In addition, the powder particle size is also relatively large. Analysis shows that this is mainly due to the mismatch between process parameters (such as rotation speed, current intensity, feed speed, etc.). Too low rotation speed or too high melting speed, during the rotating electrode atomization process, the liquid film further thickens and becomes unstable, and irregular flaky and larger particle powders are formed through the liquid film breakage mechanism. After testing, the sphericity rate is 75%, the fluidity is 13 (s / 50g), the O content is 120ppm, the H content is 90ppm, and the particle size distribution is measured by Bettersize2600 laser particle size distribution analyzer, D 10 =36.80μm, D50 =75.40μm, D 90 =99.75μm.

[0102] Since the process parameters of Comparative Example 1 are not completely within the scope of the present invention, resulting in poor parameter matching, the powder particle size becomes larger, the particle size distribution becomes more discrete, the sphericity becomes worse, and the proportion of large-sized powder and irregular powder increases.

[0103] The test method for the particle-reinforced high entropy alloy spherical powder of Example 1 and Comparative Example 1 is as follows:

[0104] Flowability and bulk density

[0105] The flowability of spherical powder was tested by using a Hall flowmeter. 50 g of powder sample was weighed and the powder was allowed to flow smoothly into the container, and the flow time was recorded.

[0106] Sphericity

[0107] The powder is photographed using a scanning electron microscope, and the ratio of the total number of spherical powder particles to the total number of test powder particles is measured in a field of view of 100 times or 500 times or less.

[0108] Powder particle size distribution

[0109] The particle size distribution of the powder is measured using a laser particle size analyzer to obtain D 10 , D 50 , D 90 Data and cumulative distribution of particle size.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A particle-reinforced high entropy alloy spherical powder, characterized in that: The ingredients and contents are as follows: Nb: 10~40at.%; Mo: 10~40at.%; Ta: 10~40at.%; Carbide particles: 0.5-10wt.%.

2. The particle-reinforced high entropy alloy spherical powder according to claim 1, characterized in that: The carbide particles are one or more of TaC, WC, ZrC and HfC.

3. A method for preparing the particle-reinforced high entropy alloy spherical powder according to claim 1 or 2, characterized in that: The following steps are involved: S1. Preparation of electrode rod ingot Weigh metal powder and carbide particle powder according to the ratio, mix them and put them into the rubber sleeve, and use cold isostatic pressing to obtain a cylindrical blank; The cylindrical blank is vacuum-encapsulated in a tantalum alloy sheath, and a powder metallurgy cylindrical sample is obtained by hot isostatic pressing. placing the powder metallurgy cylindrical sample into an electron beam vacuum melting furnace for electron beam melting to obtain a particle-reinforced refractory high entropy alloy ingot; S2. Preparation of Rotating Electrode Alloy Rod The particle-reinforced refractory high entropy alloy ingot is processed by a mechanical method to prepare a rotating electrode alloy rod; S3. Rotating electrode atomization powder making The rotating electrode alloy rod is loaded into the rotating electrode atomization powder making equipment, and after sealing, vacuum is drawn, and the rotating button is started. When the preset speed is reached, the plasma gun is started to prepare spherical powder; S4. Obtain particle-reinforced high-entropy alloy spherical powders in different particle size ranges by sieve classification.

4. The method for preparing particle-reinforced high entropy alloy spherical powder according to claim 3, characterized in that: S1 The average particle size of the metal powder is less than 80 μm; And / or, the carbide particle powder in S1 has a particle size of 1-10 μm.

5. The method for preparing the particle-reinforced high entropy alloy spherical powder according to claim 3 or 4, characterized in that: The pressing strength used in the cold isostatic pressing process of S1 is 100MPa to 500MPa, and the holding time is 5min to 30min; And / or, the hot isostatic pressing pressure in S1 is 50-300 MPa, the temperature is 1300-2000° C., and the holding time is 4-10 h.

6. The method for preparing the particle-reinforced high entropy alloy spherical powder according to claim 3 or 5, characterized in that: The electron beam melting conditions described in S1 are: electron beam power of 100-260 kW, melting rate of 25-50 kg / h, and repeated remelting for 5 times or more.

7. The method for preparing particle-reinforced high entropy alloy spherical powder according to claim 3, characterized in that: The specifications of the rotating electrode alloy rod S2 are: diameter 30mm~60mm, length 100~400mm, coaxiality based on the axis ≤0.05mm, and cross-sectional circular runout based on the axis ≤0.02mm.

8. The method for preparing particle-reinforced high entropy alloy spherical powder according to claim 3, characterized in that: S3: Load the rotating electrode alloy rod into the rotating electrode atomizing powder making equipment, seal and evacuate, then fill with argon as a protective gas, start the rotation button, and when the preset speed is reached, start the plasma gun to generate a high-temperature plasma arc between the rotating electrode alloy rod and the plasma gun. The end face of the rotating electrode alloy rod is melted to form a metal liquid film under the heating action of the plasma beam; the metal liquid film throws out tiny spherical droplets under the combined action of centrifugal force and surface tension, and the spherical droplets are quickly cooled and solidified into spherical powder.

9. The method for preparing particle-reinforced high entropy alloy spherical powder according to claim 3 or 8, characterized in that: S3: The purity of the argon gas is greater than or equal to 99.99%; And / or, the vacuum in S3 is performed so that the pressure in the device is less than 7×10 -3 Pa; And / or, S3: the distance between the rotating electrode alloy rod and the plasma gun is 5-15 mm, the feed speed is 0.5-2.0 mm / s, the preset rotation speed is 15000 r / min-40000 r / min, and the current intensity is 1300A-2000A.

10. Use of the particle-reinforced high-entropy alloy spherical powder according to claim 1 or 2 in the field of powder bed additive manufacturing.

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