Yttria dispersion strengthened NiCoCr entropy alloy powder and preparation method thereof

Abstract

The application discloses a yttrium oxide dispersion strengthened NiCoCr medium-entropy alloy powder and a preparation method thereof. The preparation method comprises the following steps: S1, ingredients are prepared according to the element ratio of 0.5-1wt% Y and 99-99.5wt% NiCoCr alloy, an alloy block ingot is prepared by vacuum smelting, and forging rolling is performed; S2, the forged and rolled alloy block ingot is mechanically processed into an alloy bar; S3, the yttrium oxide dispersion strengthened NiCoCr medium-entropy alloy powder is prepared by using a plasma rotating electrode method, the oxygen content in the atomization chamber is ensured to be not more than 100ppm during the preparation process, the inert gas in the atomization chamber is preheated to 200-280 DEG C, and the atomization preparation parameters are as follows: the rotating speed of the alloy bar is 20000-25000r / min, the feeding speed of the alloy bar is 1.5-2.0mm / s, the rotating electrode main shaft current of the rotating feeding device is 600-800A, the plasma gun power is 100-120kw, and the working current of the plasma gun is 80-120A. The yttrium oxide dispersion strengthened NiCoCr medium-entropy alloy powder prepared by the application can meet the large-scale application of additive manufacturing technology in terms of powder sphericity, fluidity and loose bulk density.

Description

Technical Field

[0001] This invention provides a yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder and its preparation method, belonging to the field of additive manufacturing powder preparation technology. Background Technology

[0002] High-entropy alloys are a class of novel materials with excellent properties, attracting widespread attention from the scientific community due to their superior mechanical properties, corrosion resistance, and thermal stability. From the perspective of mixing entropy (ΔSmix), an alloy is defined as high-entropy alloy when its ΔSmix is ​​greater than 1.5R; therefore, high-entropy alloys (HEAs) exhibit high variability in localized chemical environments. Inspired by a similar concept, medium-entropy alloys (MEAs) are being developed, with mixing entropy between 1R and 1.5R. For example, a model ternary NiCoCr medium-entropy alloy with a disordered face-centered cubic (FCC) structure.

[0003] Face-centered cubic (FCC) multicomponent alloys have shown great potential as high-performance structural materials and have therefore been extensively studied over the past decade. Ternary NiCoCr alloys, in particular, have attracted attention due to their superior low-temperature mechanical properties. Compared to any other binary, ternary, quaternary, or even quinary HEA alloys, NiCoCr exhibits a greater strength-to-ductility trade-off. However, the simplicity of the internal phases in ternary NiCoCr alloys improves the manufacturability of alloys like NiCoCr but also limits their high-temperature mechanical properties.

[0004] Powder materials, as the most fundamental raw materials for additive manufacturing, are a crucial component of the additive manufacturing industry chain. The properties of metal powders have a key impact on the stability of additive manufacturing processes, forming precision, and product microstructure and properties. Although dispersion strengthening is an effective strengthening mechanism, incorporating it into a metal matrix is ​​an extremely difficult manufacturing challenge, and it remains challenging for many applications. Conventional dispersion-strengthened alloys are typically manufactured through mechanical alloying processes, where the dispersions are alloyed using high-energy ball milling to form a mixed powder. This mixed powder contains various metal powders with different melting points, making it prone to oxidation during mixing and resulting in uneven distribution of coarse and fine particles, leading to uneven dispersion of the elemental dispersions. Furthermore, using mechanically alloyed powders for additive manufacturing presents problems because the highly deformable powders have poor flowability, thus reducing raw material transport performance. Currently developed NiCoCr alloy powders are prepared using mechanical alloying methods, but they fall short of meeting the requirements for large-scale application in additive manufacturing in terms of powder sphericity, flowability, and loose packing density. There is an urgent need to develop a NiCoCr medium-entropy alloy powder with high sphericity and excellent high-temperature mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of high-performance additive manufacturing technology that is difficult to achieve with existing NiCoCr alloy powders, and to propose a yttrium oxide dispersion-reinforced NiCoCr medium-entropy alloy powder with high sphericity and excellent high-temperature mechanical properties and its preparation method.

[0006] The technical solution adopted by this invention to achieve its objective is: a yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder and its preparation method, the preparation method comprising the following steps:

[0007] S1. The alloy is prepared by batching according to the element ratio of 0.5-1wt% Y and 99-99.5wt% NiCoCr alloy, and the alloy ingot is prepared by vacuum melting and then forged and rolled.

[0008] S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method.

[0009] S3. Preparation of yttrium oxide dispersion-reinforced NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including:

[0010] s31. Load the alloy rod prepared in step S2 into the rotary feed device, evacuate the atomization chamber to the preset vacuum level, and then fill it with inert gas so that the gas pressure in the atomization chamber reaches the preset gas pressure. Monitor the oxygen content in the atomization chamber to ensure that the oxygen content in the atomization chamber is not greater than 100ppm.

[0011] s32. Preheat the inert gas in the atomization chamber to 200-280℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, the powder in the powder collection device is vacuum-sealed for preservation. The atomization preparation parameters are: the rotation speed of the alloy rod is 20000-25000 r / min, the feed speed of the alloy rod is 1.5-2.0 mm / s, the spindle current of the rotary electrode of the rotary feed device is 600-800A, the plasma gun power is 100-120kw, and the working current of the plasma gun is 80-120A.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] I. This invention involves mixing raw materials according to the designed chemical composition ratio of medium-entropy alloy powder, and then using vacuum melting technology to melt the mixture into alloy ingots, enabling the in-situ synthesis of yttrium oxide within a medium-entropy alloy matrix. This direct in-situ nucleation and growth method within the matrix avoids the drawback of poor compatibility between oxide particles and the matrix. During subsequent powder preparation, all alloy components in the powder are fully alloyed, eliminating the need for additional mechanical alloying and thus avoiding issues such as reduced flowability due to loss of sphericity caused by mechanical alloying. During solidification, the added Y element provides compositional supercooling, promoting grain refinement. Y can combine with O elements in the alloy matrix to form Y₂O₃ particles, reducing the O content in the matrix. The generated Y₂O₃ can also pin grain boundaries and inhibit grain growth.

[0014] II. In the plasma rotary atomization process of this invention, the high-speed rotation of the rod material enables a more uniform distribution of elements in the NiCoCr matrix. Simultaneously, the centrifugal force generated by the rod rotation promotes the uniform distribution of the Y₂O₃ precipitate on the powder surface. Furthermore, the introduction of Y element reduces the surface tension in the molten pool, leading to a decrease in the viscosity of the molten pool. During plasma rotary electrode atomization, the centrifugal force generated by rotation makes it easier for molten droplets to separate from the rod material, thus reducing the average particle size of the powder. The temperature of the plasma arc in plasma rotary electrode atomization can reach several thousand degrees Celsius, providing a significant undercooling for the solidification of the alloy powder, which helps to suppress the growth of Y₂O₃, thereby forming a fine, dispersed phase.

[0015] III. The atomization preparation parameters of this invention were obtained through numerous experiments and repeated verifications, which are analyzed in detail below:

[0016] The oxygen content in the plasma rotation equipment is controlled at 100 ppm to avoid high oxygen content in the powder during atomization, which would cause the O element in the alloy to solidify and harden into a matrix, resulting in brittle powder and reduced toughness.

[0017] Preheating the inert gas in the atomization chamber to 200-280℃ can preheat the bar stock and atomization chamber, allowing them to maintain a relatively high temperature and preventing the bar stock from cracking due to sudden heating during plasma arc heating.

[0018] The rotational speed of the alloy bar was set at 20,000-25,000 r / min, which was obtained by considering the density adjustment process parameters of the NiCoCr alloy. A higher rotational speed yields smaller alloy powder particles, but if the particle size is too small (tens of micrometers), the powder's adhesion exceeds its gravity, resulting in lower powder flowability. Furthermore, excessively high rotational speeds can cause the high-density NiCoCr alloy to resonate with the equipment, leading to bar breakage. Conversely, excessively low rotational speeds result in excessively large medium-entropy powder particles with poor flowability. Therefore, a rotational speed of 20,000-25,000 r / min was ultimately chosen.

[0019] The feed rate of the alloy bar is set to 1.5-2.0 mm / s, mainly based on the high-temperature melting rate of the NiCoCr alloy. If the feed rate is too fast, the NiCoCr alloy will not atomize sufficiently; if it is too slow, the atomization powder production efficiency will be too low. The plasma gun power is selected as 100-120 kW. The plasma gun first excites the secondary arc, which further awakens and maintains the main arc. Increasing the plasma gun power will make the operation of the secondary and main arcs more stable. However, the plasma gun power cannot be increased indefinitely; issues such as plasma gun overheating and power consumption limits must be considered. Therefore, a power of 100-120 kW is selected. The rotary spindle current of the rotary feed device is selected to be 600-800A. On the one hand, this increases the plasma arc and accelerates the atomization speed of the bar stock, thereby improving atomization efficiency. However, if the spindle current is too high, the diameter of the plasma arc will be too large, leading to excessive heat load and power consumption. The rotary spindle current selected in this invention is matched with other atomization rate parameters such as the feed speed of 1.0-2.0 mm / s. The working current of the plasma gun is 100-120A. This is because a higher current makes it easier to awaken the main arc through the secondary arc, thereby improving the production efficiency of medium-entropy alloy powder. The working current of the plasma gun and the power of the plasma gun are positively correlated and related to the intensity of the plasma arc. As the value increases, it is beneficial to awaken and stabilize the main plasma arc. However, considering the power consumption, an upper limit should be set, and the problem of overheating of the plasma gun should be prevented. Therefore, the working current of the plasma gun is selected to be 100-120A.

[0020] Furthermore, the vacuum melting in step S1 of this invention is either vacuum arc self-consuming melting or vacuum induction melting. Argon gas is used for protection during the melting process, the melting power is 100K-140KW, and the number of melting times is 2-4.

[0021] Furthermore, the specific steps of step S1, vacuum melting, in this invention are as follows: First, the metal ingredients are placed in a vacuum melting furnace, and a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶ in the furnace. -3 -1×10 -2Then, argon gas is introduced for protection, the power is turned on and the melting power is set to start melting. After the raw material is melted, the power is maintained for 5-10 minutes, the power is turned off, and the power is turned on again after 4-6 minutes to continue melting. After melting 2-4 times, the temperature is lowered and the material is cast. The material is then cooled in the furnace for 30 minutes before being taken out of the furnace. The melting power is 100K-140KW.

[0022] Furthermore, in step S1 of the present invention, the forging and rolling temperature is 800-1100℃, the holding time is 80-140 min, and the deformation of the forging during the forging process is 30%-50%.

[0023] Furthermore, the alloy bar processed in step S2 of the present invention has a length of 150-200mm, a diameter of 29-31mm, and a surface roughness Ra of no more than 1.6μm.

[0024] NiCoCr alloy has a high density, so excessively long or thin rods can easily cause resonance with the atomization equipment, leading to premature breakage of the high-speed rotating rod and creating experimental hazards. Conversely, excessively short rods result in reduced powder production per batch, leading to longer rod replacement cycles and impacting production efficiency. Furthermore, excessively thick rods can cause insufficient plasma arc atomization, making it difficult to completely cover the rod. Therefore, after extensive testing, the optimal length for the NiCoCr alloy rods in this invention is determined to be 150-200 mm, and the diameter to be 29-31 mm.

[0025] Furthermore, in the atomization powder preparation process in step S3 of the present invention, the inert gas introduced into the atomization chamber is argon.

[0026] Furthermore, in step s31 of the present invention, the preset vacuum degree for evacuating the atomizing chamber to a preset vacuum degree is 1×10⁻⁶. -3 -1×10 -2 Pa, inert gas is introduced to bring the pressure in the atomization chamber to a preset pressure of 1.6 × 10⁻⁶. 5 -1.8×10 5 Pa. Attached Figure Description

[0027] Figure 1 Scanning electron microscope (SEM) images of the NiCoCr medium-entropy alloy powder prepared in Comparative Example 1 at different magnifications.

[0028] Figure 2 The images are scanning electron microscope (SEM) images of the yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder prepared in Example 1 at different magnifications.

[0029] Figure 3 This is an energy dispersive spectroscopy (EDS) surface scan image of the yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder prepared in Example 1.

[0030] Figure 4 This is a comparison diagram of the particle size distribution of NiCoCr medium-entropy alloy powder prepared in Comparative Example 1 and Example 1.

[0031] In the figure, NiCoCr represents the NiCoCr medium-entropy alloy powder prepared in Comparative Example 1, and NiCoCr-Y represents the yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder prepared in Example 1. Detailed Implementation

[0032] Comparative Example 1

[0033] A NiCoCr medium-entropy alloy powder and its preparation method, the preparation method comprising the following steps:

[0034] S1. The elements of the NiCoCr alloy with equal atomic ratio are batched, and alloy ingots are prepared by vacuum melting and then forged and rolled.

[0035] The steps for preparing alloy ingots by vacuum melting are as follows: first, the furnace is loaded, and then a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶. -3 Argon gas was introduced for protection, the power was turned on and the melting power was set to 140KW to start melting. After the raw material was melted, the power was maintained for 10 minutes, the power was turned off, and the power was turned on again after 5 minutes to continue melting. After melting 4 times, the temperature was lowered and cast, and the casting was cooled in the furnace for 30 minutes before being taken out of the furnace. The forging and rolling temperature was 960℃, the holding time was 100 minutes, and the deformation of the forging during the forging process was 50%.

[0036] S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method; the machined alloy bars are 160 mm long, 29.2 mm in diameter, and have a surface roughness Ra of no more than 1.6 μm.

[0037] S3. Preparation of NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including:

[0038] s31. Load the alloy rod prepared in step S2 into the rotary feed device, and evacuate the atomization chamber to the preset vacuum level of 8.6 × 10⁻⁶. -3 After Pa, argon gas is introduced to bring the pressure in the atomization chamber to the preset pressure of 1.7 × 10⁻⁶. 5 Pa, monitor the oxygen content in the atomization chamber, and ensure that the oxygen content in the atomization chamber is not greater than 100 ppm;

[0039] s32. Preheat the inert gas in the atomization chamber to 200℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, the powder in the powder collection device is vacuum-sealed for preservation. The atomization preparation parameters are: the rotation speed of the alloy rod is 20000 r / min, the feed speed of the alloy rod is 1.5 mm / s, the spindle current of the rotary electrode of the rotary feed device is 800 A, the power of the plasma gun is 120 kW, and the working current of the plasma gun is 120 A.

[0040] Example 1

[0041] A yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder and its preparation method, the preparation method comprising the following steps:

[0042] S1. The alloy is prepared by batching according to the element ratio of 1wt% Y and 99wt% NiCoCr alloy, and the alloy ingot is prepared by vacuum melting and then forged and rolled.

[0043] The steps for preparing alloy ingots by vacuum melting are as follows: first, the furnace is loaded, and then a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶. -3 Argon gas was introduced for protection, the power was turned on and the melting power was set to 140KW to start melting. After the raw material was melted, the power was maintained for 10 minutes, the power was turned off, and the power was turned on again after 5 minutes to continue melting. After melting 4 times, the temperature was lowered and cast, and the casting was cooled in the furnace for 30 minutes before being taken out of the furnace. The forging and rolling temperature was 960℃, the holding time was 100 minutes, and the deformation of the forging during the forging process was 50%.

[0044] S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method; the machined alloy bars are 160 mm long, 29.2 mm in diameter, and have a surface roughness Ra of no more than 1.6 μm.

[0045] S3. Preparation of NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including:

[0046] s31. Load the alloy rod prepared in step S2 into the rotary feed device, and evacuate the atomization chamber to the preset vacuum level of 8.6 × 10⁻⁶. -3 After Pa, argon gas is introduced to bring the pressure in the atomization chamber to the preset pressure of 1.7 × 10⁻⁶. 5 Pa, monitor the oxygen content in the atomization chamber, and ensure that the oxygen content in the atomization chamber is not greater than 100 ppm;

[0047] s32. Preheat the inert gas in the atomization chamber to 200℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, the powder in the powder collection device is vacuum-sealed for preservation. The atomization preparation parameters are: the rotation speed of the alloy rod is 20000 r / min, the feed speed of the alloy rod is 1.5 mm / s, the spindle current of the rotary electrode of the rotary feed device is 800 A, the power of the plasma gun is 120 kW, and the working current of the plasma gun is 120 A.

[0048] Figure 1 This is a scanning electron microscope (SEM) image of the NiCoCr medium-entropy alloy powder prepared in Comparative Example 1. SEM observation shows that the powder particles in the comparative example have larger diameters, irregular shapes, slightly rough surfaces, more satellite particles, poorer overall sphericity, and more irregular particles.

[0049] Figure 2 This is a scanning electron microscope (SEM) image of the NiCoCr medium-entropy alloy powder prepared in Example 1. SEM observation shows that the powder particles in this case are highly regular, with smooth and rounded surfaces and very few satellite spheres. The overall sphericity of the powder particles is high, with few other irregular particles, and a large number of obvious dispersed particles can be found on the powder surface, indicating a significant improvement in surface morphology quality.

[0050] Figure 3 This is an energy dispersive spectroscopy (EDS) image of the NiCoCr medium-entropy alloy powder prepared in Example 1. By performing a surface scan of the powder surface at 10,000x magnification, it was found that there was significant enrichment of Y element in the dispersed phase of the powder particles, but no significant enrichment of other elements was observed. Based on the analysis in the article, it was determined to be a dispersed distribution of yttrium oxide.

[0051] Figure 4Table 1 shows a comparison of the particle size distribution of the NiCoCr medium-entropy alloy powders prepared in Comparative Example 1 and Example 1. Table 1 also shows the powder parameters D10, D50, and D90 of the NiCoCr medium-entropy alloy powders prepared in Example 1 and Comparative Example 1. As can be seen from Table 1, the particle size parameters D10, D50, and D90 of the NiCoCr-Y medium-entropy alloy powder prepared in Example 1 are 49.90 μm, 75.96 μm, and 134.2 μm, respectively, while the D10, D50, and D90 of the NiCoCr alloy powder prepared in Comparative Example 1 are 51.15 μm, 89.57 μm, and 164.2 μm, respectively. This indicates a significant refinement in the particle size of the NiCoCr-Y alloy. The powder flowability was measured by a Hall flowmeter, and the results are shown in Table 2. As can be seen from Table 2, the average time for 50g of NiCoCr-Y alloy powder to pass through the funnel was the shortest, which was 14.17s, while the time for NiCoCr alloy powder was 14.41s. This indicates that NiCoCr-Y alloy powder actually has the best flowability. Therefore, as the Y content increases, the powder flowability gradually increases.

[0052] Table 1. Powder parameters of NiCoCr medium-entropy alloy powder prepared in Example 1 and Comparative Example 1.

[0053]

[0054] Table 2. Powder flowability of NiCoCr medium-entropy alloy powders prepared in Example 1 and Comparative Example 1.

[0055]

[0056] Example 2

[0057] A yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder and its preparation method, the preparation method comprising the following steps:

[0058] S1. The alloy is prepared by batching according to the element ratio of 0.5wt% Y and 99.5wt% NiCoCr alloy with equal atomic ratio, and the alloy ingot is prepared by vacuum melting and then forged and rolled.

[0059] The steps for preparing alloy ingots by vacuum melting are as follows: first, the furnace is loaded, and then a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶. -3 Argon gas was introduced for protection, the power was turned on and the melting power was set to 100KW to start melting. After the raw material was melted, the power was maintained for 5 minutes, the power was turned off, and the power was turned on again after 5 minutes to continue melting. After melting 4 times, the temperature was lowered and cast, and the casting was cooled in the furnace for 30 minutes before being taken out of the furnace. The forging and rolling temperature was 800℃, the holding time was 140 minutes, and the deformation of the forging during the forging process was 30%.

[0060] S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method; the machined alloy bars are 150mm long, 29mm in diameter, and have a surface roughness Ra of no more than 1.6μm.

[0061] S3. Preparation of NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including:

[0062] s31. Load the alloy rod prepared in step S2 into the rotary feed device, and evacuate the atomization chamber to the preset vacuum level of 8.6 × 10⁻⁶. -3 After Pa, argon gas is introduced to bring the pressure in the atomization chamber to the preset pressure of 1.7 × 10⁻⁶. 5 Pa, monitor the oxygen content in the atomization chamber, and ensure that the oxygen content in the atomization chamber is not greater than 100 ppm;

[0063] s32. Preheat the inert gas in the atomization chamber to 280℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, the powder in the powder collection device is vacuum-sealed for preservation. The atomization preparation parameters are: the rotation speed of the alloy rod is 25000 r / min, the feed speed of the alloy rod is 2 mm / s, the spindle current of the rotary electrode of the rotary feed device is 600A, the power of the plasma gun is 100 kW, and the working current of the plasma gun is 80A.

[0064] Example 3

[0065] A yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder and its preparation method, the preparation method comprising the following steps:

[0066] S1. The alloy is prepared by batching according to the element ratio of 0.7wt% Y and 99.3wt% NiCoCr alloy with equal atomic ratio, and the alloy ingot is prepared by vacuum melting and then forged and rolled.

[0067] The steps for preparing alloy ingots by vacuum melting are as follows: first, the furnace is loaded, and then a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶. -3 Argon gas was introduced for protection, the power was turned on and the melting power was set to 130KW to start melting. After the raw materials were melted, the power was maintained for 8 minutes, the power was turned off, and the power was turned on again after 5 minutes to continue melting. After melting twice, the temperature was lowered and cast, and the casting was carried out after cooling in the furnace for 30 minutes. The forging and rolling temperature was 1100℃, the holding time was 80 minutes, and the deformation of the forging during the forging process was 40%.

[0068] S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method; the machined alloy bars are 200mm long, 31mm in diameter, and have a surface roughness Ra of no more than 1.6μm.

[0069] S3. Preparation of NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including:

[0070] s31. Load the alloy rod prepared in step S2 into the rotary feed device, and evacuate the atomization chamber to a preset vacuum level of 9×10. -3 After Pa, argon gas is introduced to bring the pressure in the atomization chamber to the preset pressure of 1.7 × 10⁻⁶. 5 Pa, monitor the oxygen content in the atomization chamber, and ensure that the oxygen content in the atomization chamber is not greater than 100 ppm;

[0071] s32. Preheat the inert gas in the atomization chamber to 240℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, the powder in the powder collection device is vacuum-sealed for preservation. The atomization preparation parameters are: the rotation speed of the alloy rod is 23000 r / min, the feed speed of the alloy rod is 1.7 mm / s, the spindle current of the rotary electrode of the rotary feed device is 700 A, the power of the plasma gun is 110 kW, and the working current of the plasma gun is 100 A.

Claims

1. A method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder, characterized in that: Includes the following steps: S1. The alloy is prepared by batching according to the element ratio of 0.5-1wt% Y and 99-99.5wt% NiCoCr alloy, and the alloy ingot is prepared by vacuum melting and then forged and rolled. S2. The forged and rolled alloy ingot is machined into alloy bars that meet the dimensional requirements of the plasma rotating electrode method. S3. Preparation of yttrium oxide dispersion-reinforced NiCoCr medium-entropy alloy powder using the plasma rotating electrode method, specifically including: s31. Load the alloy rod prepared in step S2 into the rotary feed device, evacuate the atomization chamber to the preset vacuum level, and then fill it with inert gas so that the gas pressure in the atomization chamber reaches the preset gas pressure. Monitor the oxygen content in the atomization chamber to ensure that the oxygen content in the atomization chamber is not greater than 100ppm. s32. Preheat the inert gas in the atomization chamber to 200-280℃, start the rotary feed device and plasma gun power supply for atomization powder preparation. A high-temperature plasma arc is generated between the alloy rod and the plasma gun. Under the combined action of centrifugal force and surface tension, the rod melts and forms tiny droplets, which then solidify into metal powder. After the powder has completely cooled, vacuum seal and preserve the powder in the powder collection device. The atomization preparation parameters are: the rotation speed of the alloy rod is 20000-25000 r / min, the feed speed of the alloy rod is 1.5-2.0 mm / s, the spindle current of the rotary electrode of the rotary feed device is 600-800A, the plasma gun power is 100-120kw, and the working current of the plasma gun is 80-120A.

2. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: The vacuum melting in step S1 is either vacuum arc self-consuming melting or vacuum induction melting. Argon gas is used for protection during the melting process. The melting power is 100K-140KW, and the melting times are 2-4 times.

3. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: The specific steps of step S1, vacuum melting, are as follows: First, the metal ingredients are placed in a vacuum melting furnace, and a vacuum is drawn to achieve a vacuum degree of 1×10⁻⁶ in the furnace. -3 -1×10 -2 Then, argon gas is introduced for protection, the power is turned on and the melting power is set to start melting. After the raw material is melted, the power is maintained for 5-10 minutes, the power is turned off, and the power is turned on again after 4-6 minutes to continue melting. After melting 2-4 times, the temperature is lowered and the material is cast. The material is then cooled in the furnace for 30 minutes before being taken out of the furnace. The melting power is 100K-140KW.

4. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: The forging and rolling temperature in step S1 is 800-1100℃, the holding time is 80-140 min, and the deformation of the forging during the forging process is 30%-50%.

5. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: The alloy bar processed in step S2 has a length of 150-200mm, a diameter of 29-31mm, and a surface roughness Ra of no more than 1.6μm.

6. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: In step S3, the inert gas introduced into the atomization chamber during the atomization powder production process is argon.

7. The method for preparing yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder according to claim 1, characterized in that: In step s31, the atomizing chamber is evacuated to a preset vacuum level of 1×10⁻⁶. -3 -1×10 -2 Pa, inert gas is introduced to bring the pressure in the atomization chamber to a preset pressure of 1.6 × 10⁻⁶. 5 -1.8×10 5 Pa.

8. A yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder, characterized in that: The yttrium oxide dispersion-strengthened NiCoCr medium-entropy alloy powder is prepared by the preparation method described in any one of claims 1-7.

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