A nickel-based alloy powder resistant to high-temperature creep, a vacuum gas atomization preparation method and application thereof

Abstract

This invention discloses a nickel-based alloy powder resistant to high-temperature creep, with the following chemical composition and percentage (wt%): Cr: 22.2-22.8, Nb: 0.9-1.1, Ti: 3.6-3.8, Al: 1.8-2.0, B: 0.004-0.012, Co: 18.5-19.5, W: 1.8-2.2, Ta: 1.3-1.5, Zr: 0.05-0.14, C: 0.13-0.17, La: 0.01-0.08, Y: 0.002-0.005, and the total content of La + Y is 0.012-0.085, with the balance being Ni and unavoidable impurities; the content of P and S elements does not exceed 0.02%. This nickel-based alloy powder can improve oxidation resistance, increase grain boundary strength, and reduce hot cracking susceptibility. Meanwhile, the present invention also provides a method for preparing nickel-based alloy powder, which can reduce hollow powder, increase density, and meet the stringent requirements of In939 alloy powder for high-end additive manufacturing.

Description

Technical Field

[0001] This invention relates to a nickel-based alloy powder, its preparation method, and its application. Background Technology

[0002] In939 is a typical γ′ phase (Ni3(Al,Ti)) precipitation-strengthened nickel-based superalloy. Due to its excellent high-temperature strength and resistance to hot corrosion, it has become a core material for additive manufacturing of precision hot-end components such as turbine blades and combustion chambers in aero-engines. With the increasing application of additive manufacturing technology in the aerospace field, the preparation quality and formability of In939 alloy powder have become key factors restricting its engineering applications.

[0003] Currently, vacuum atomization (VIGA) is the mainstream process for industrial preparation of high-performance In939 alloy powder. However, traditional In939 alloy powder prepared by existing vacuum atomization has problems such as high hollow powder ratio (5-10%), high oxygen content (>150ppm), and sensitivity to printing hot cracks, which seriously affect the density and mechanical properties of additively manufactured parts. Specifically, it is described as follows: (1) Sensitivity to printing hot cracks: The Al+Ti content of In939 alloy is as high as 5.4~5.8%, so it is sensitive to rapid solidification (10³-10) in additive manufacturing. 6Under the condition of K / s), significant thermal stress and solidification shrinkage stress will be generated during the liquid-solid phase transformation of the alloy, resulting in the problem of insufficient powder grain boundary strengthening elements and weak grain boundary bonding force. Ultimately, a large number of intergranular microcracks will be generated at the grain boundaries of the formed parts, which will seriously reduce the mechanical properties and service reliability of the components; (2) Insufficient grain boundary strength: The content of B and Zr in In939 alloy is limited, and during long-term service at high temperatures above 900℃, brittle borides and carbides are easily precipitated at the grain boundaries and harmful elements will segregate, resulting in a rapid decay of the grain boundary strengthening effect. Its creep fracture life at 900℃ and 200MPa is only 200-300 hours, which cannot meet the core requirements for long-term service of hot-end components of aero-engines; (3) The oxidation resistance needs to be improved: In939 alloy at 90℃ and 200MPa has a low oxidation resistance of 900℃ and 200MPa. In high-temperature oxidation environments above 0℃, the Cr2O3 main oxide film generated on the surface has poor density and poor adhesion to the substrate, and is prone to oxide film cracking, peeling and internal oxidation, which cannot meet the anti-oxidation protection requirements for long-term high-temperature service; (4) High hollow powder rate: Traditional VIGA process generally uses high superheat above 250℃, and the parameters such as atomization pressure and gas temperature are not matched with the surface tension and viscosity characteristics of In939 melt, which leads to the formation of hollow powder due to gas entrainment during the atomization process. The hollow powder rate is as high as 5-10%, and the hollow powder is prone to cracking during the selective laser melting process and laser melting, forming irregular interconnected pore defects inside the formed part, which directly leads to the density of the formed part dropping to below 99.3%, and at the same time becomes the core source of fatigue crack initiation. That is, the existing In939 powder and its additive manufacturing formed parts have a full-chain bottleneck from powder preparation to component service, which seriously restricts its engineering batch application. Summary of the Invention

[0004] The problem this invention aims to solve is to provide a nickel-based alloy powder resistant to high-temperature creep, which can improve oxidation resistance, increase grain boundary strength, and reduce hot cracking susceptibility. Simultaneously, this invention also provides a method for preparing the nickel-based alloy powder, which can reduce hollow powder, increase density, and meet the stringent requirements of In939 alloy powder for high-end additive manufacturing.

[0005] This invention discloses a nickel-based alloy powder resistant to high-temperature creep, the chemical composition and percentage (wt%) of which are: Cr: 22.2-22.8, Nb: 0.9-1.1, Ti: 3.6-3.8, Al: 1.8-2.0, B: 0.004-0.012, Co: 18.5-19.5, W: 1.8-2.2, Ta: 1.3-1.5, Zr: 0.05-0.14, C: 0.13-0.17, La: 0.01-0.08, Y: 0.002-0.005, and the total content of La + Y is 0.012-0.085, with the balance being Ni and unavoidable impurities; the content of P and S elements does not exceed 0.02%.

[0006] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.02, Y: 0.003.

[0007] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.04, Y: 0.003.

[0008] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.003.

[0009] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.08, Y: 0.003.

[0010] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.004.

[0011] The preferred composition of the nickel-based alloy powder is: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.005.

[0012] The present invention provides a vacuum atomization preparation method for nickel-based alloy powder, comprising the following steps: (1) Batching and loading: Batching is carried out according to the composition ratio of nickel-based alloy powder, wherein easily burnable elements are added during the secondary feeding process, and the remaining raw materials are filled into the melting crucible before melting, and placed according to the principle of being dense at the bottom and loose in the middle and upper parts; (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and when the vacuum degree is less than 50Pa, proceed to the next step; (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas filling valve, and fill the gas pressure to 0.7MPa. When the furnace pressure reaches 6×10 4When the pressure reaches Pa, stop the gas filling process and repeat the above vacuuming and gas replacement steps three times. The furnace pressure is 1×10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protected melting: Increase the power of the melting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the melting crucible at high power and refine at 1480℃ for 10 minutes, while tilting the crucible 3 times to homogenize the liquid; (5) Inert gas atomization: Use high-purity argon gas (99.999%) preheated to 100~150°C for atomization. When the liquid temperature reaches 1510℃, open the atomizing gas pressure regulating valve and quickly adjust the pressure to 2.5-2.6. MPa, and at the same time, the molten liquid is poured into the intermediate ladle. The molten liquid flows out from the intermediate ladle through the guide nozzle with a diameter of 4.5 mm at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is crushed, atomized and solidified by high pressure argon gas into the nickel-based alloy powder. Among them, 5-8 minutes before pouring the liquid, the six raw materials, namely titanium rod, high-purity aluminum, nickel boron, metallic zirconium, nickel lanthanum alloy and nickel yttrium alloy, are added to the melting crucible through the secondary feeding cylinder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder of 15-45 μm.

[0013] The nickel-based alloy powder of this invention has the following characteristics: hollow powder content less than 1.5%, rare earth solid solution success rate (La) 85%, room temperature elongation 22.1%, impact energy 41J, creep rupture life at 816℃ / 250MPa 395h, and oxidation weight gain of 1.14mg / cm³ at 900℃ for 100h. 3 .

[0014] The nickel-based alloy powder obtained by the preparation method of this invention is used in laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a forming density of 99.8%.

[0015] The advantages of the alloy powder and preparation method of this invention are as follows: 1. Addition of La+Y: Based on the existing In939 standard composition, a La+Y composite component is added, with a total content of 0.012-0.085%, Y of 0.002-0.005%, and La of 0.01-0.08%. Y microalloying purifies grain boundaries and improves wettability; La modifies the oxide film and improves oxidation resistance; the two work synergistically to improve grain boundary strength and reduce hot crack sensitivity; the content of La and Y is very low because the solid solubility of La and Y in Ni-based materials is very low, and Y in Ni exceeding 0.01% easily forms the Ni5Y brittle phase; 2. Precise rare earth addition technology: Rare earth is added stepwise in the later stage of vacuum melting in the form of Ni-La and Ni-Y master alloys, avoiding oxidation loss caused by premature addition of rare earth, ensuring uniform and precise distribution of rare earth, and improving the rare earth solid solution efficiency to >80%; 3. Specialized gas atomization process: The superheat is precisely matched to 140-160°C (lower than the traditional process of more than 190°C), and the atomization pressure is dynamically adjusted to 2.5-2.6MPa (higher than the traditional process of more than 2.4MPa). Preheated gas (100-150°C) and inert gas protective atmosphere are used, and the characteristics of the melt after rare earth modification are optimized in conjunction with the process to suppress the formation of hollow powder from the source. 4. Process-composition synergistic optimization: The surface tension and viscosity of the melt change after rare earth modification. By reducing the superheat and preheating the atomizing gas, the melt fluidity is improved, gas entrainment is reduced, and the hollow powder rate is reduced to <2%.

[0016] In summary, this invention effectively suppresses gas entrainment during melt fragmentation by modifying the alloy composition and through synergistic optimization of low superheat control and atomized gas preheating, thereby reducing the generation of hollow powder from the source and ensuring that the overall powder quality meets the stringent requirements of In939 alloy powder for high-end additive manufacturing. Attached Figure Description

[0017] Figure 1 The image shows a scanning electron microscope (SEM) image (1000x magnification) of the powder particles obtained in Example 8.

[0018] Figure 2 This is a cross-sectional metallographic image of the powder particles obtained in Example 8. Detailed Implementation

[0019] The present invention will be further described in detail below through examples and comparative examples.

[0020] Comparative Example 1: Existing Traditional Preparation Process of In939 A nickel-based alloy powder has the following chemical composition by mass percentage: Cr: 22.5%, Nb: 1.0%, Ti: 3.7%, Al: 1.9%, B: 0.008%, Co: 19.0%, W: 2.0%, Ta: 1.4%, Zr: 0.10%, C: 0.15%, with the balance being Ni and unavoidable impurities; the content of P and S elements does not exceed 0.02%. The specific preparation process is as follows: (1) Batching and loading: The total weight of the materials is 50 kg. The materials include 11.25 kg of metallic chromium, 0.50 kg of nickel bars, 1.90 kg of titanium rods, 1.00 kg of high-purity aluminum, 0.02 kg of nickel boron, 9.50 kg of electrolytic cobalt, 1.00 kg of pure tungsten, 0.70 kg of tantalum ingots, 0.05 kg of metallic zirconium, 24.005 kg of nickel plates and 0.075 kg of carbon raiser. The four easily burnable elements, titanium rods, high-purity aluminum, nickel boron and metallic zirconium, are added during the secondary feeding process. The remaining raw materials are filled into the smelting crucible and placed according to the principle of being dense at the bottom and loose in the middle and upper parts to prevent bridging during smelting. (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and proceed to the next step when the vacuum degree is less than 50Pa.

[0021] (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas charging valve, and charge at a pressure of 0.7 MPa. When the furnace pressure reaches 6 × 10⁻⁶ MPa... 4 When the pressure reaches Pa, stop the gas filling process and repeat the above vacuuming and gas replacement steps three times. The furnace pressure is 1×10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protection smelting: Increase the power of the smelting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the smelting crucible at high power and refine it at 1480℃ for 10 minutes, while tilting the crucible 3 times to make the liquid uniform. (5) Inert gas atomization: When the temperature of the melt reaches 1560℃, open the atomizing gas pressure regulating valve and quickly adjust it to 2.3MPa pressure and 1600 standard cubic meters / hour flow rate. At the same time, start pouring the melt into the tundish. The melt flows out from the tundish through the 4.5mm diameter guide nozzle at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is broken, atomized and solidified by high pressure argon gas into the nickel-based alloy powder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder with a size of 15-45μm.

[0022] The nickel-based alloy powder prepared by this comparative method has a hollow powder ratio of 6.5%, which is used for laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a forming density of 99.2%.

[0023] Example 1 The alloy powder used in this embodiment is the alloy powder of the present invention, that is, La+Y is added to the original In939 alloy composition: Ni-La master alloy (La content 10%) and Ni-Y master alloy (Y content 5%) are used, that is, the content of La element is increased by 0.06% and the content of Y element is increased by 0.004%. The preparation process is basically the same as that of Comparative Example 1. (1) Batching and loading: The total weight of the materials is 50 kg. The materials include 11.25 kg of metallic chromium, 0.50 kg of nickel bars, 1.90 kg of titanium rods, 1.00 kg of high-purity aluminum, 0.02 kg of nickel boron, 9.50 kg of electrolytic cobalt, 1.00 kg of pure tungsten, 0.70 kg of tantalum ingots, 0.05 kg of metallic zirconium, 23.325 kg of nickel plates, 0.60 kg of nickel-lanthanum alloy, 0.08 kg of nickel-yttrium alloy and 0.075 kg of carbon raiser. The six easily burnable elements, titanium rods, high-purity aluminum, nickel boron, metallic zirconium, nickel-lanthanum alloy and nickel-yttrium alloy, are added during the secondary feeding process. The remaining raw materials are filled into the melting crucible before melting, and are placed according to the principle of being dense at the bottom and loose in the middle and upper parts to prevent bridging during melting. (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and proceed to the next step when the vacuum degree is less than 50Pa; (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas charging valve, and charge at a pressure of 0.7 MPa. When the furnace pressure reaches 6 × 10⁻⁶ MPa... 4 Stop charging when the pressure reaches 1 Pa. Repeat the above vacuuming and gas replacement steps three times. The furnace pressure should be 1 × 10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protection smelting: Increase the power of the smelting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the smelting crucible at high power and refine it at 1480℃ for 10 minutes, while tilting the crucible 3 times to make the liquid uniform. (5) Inert gas atomization: When the molten liquid temperature reaches 1560℃, open the atomizing gas pressure regulating valve and quickly adjust it to 2.3MPa pressure and 1600 standard cubic meters / hour flow rate. At the same time, start pouring the molten liquid into the tundish. The molten liquid flows out from the tundish through the 4.5mm diameter guide nozzle at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is crushed, atomized and solidified by high pressure argon gas into the nickel-based alloy powder. Among them, 6 minutes before pouring the liquid, the six raw materials, namely titanium rod, high-purity aluminum, nickel boron, metallic zirconium, nickel lanthanum alloy and nickel yttrium alloy, are added to the melting crucible through the secondary feeding cylinder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder with a size of 15-45μm.

[0024] Compared to the existing In939, the material in this embodiment undergoes La+Y composite modification to optimize material properties, further improving oxidation resistance and grain boundary strength. The nickel-based alloy powder prepared in this embodiment is used for laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a forming density of 99.2%.

[0025] Examples 2-6 Examples 2-6 differ from Example 1 in that the percentage of alloy powder composition is changed, but the process remains the same.

[0026] The percentages of alloy powder components in Examples 1-6 are shown in Table 1.

[0027] Table 1

[0028] Example 7 The alloy powder and composition in this embodiment are the same as in Example 1, but the process parameters are optimized: atomization pressure 2.5-2.6 MPa, atomization gas preheated to 100-150°C, and other parameters are the same as in Example 1. This combination of parameters further reduces the hollow powder ratio to 2.8%. The specific preparation process is as follows: (1) Batching and loading: The total weight of the materials is 50 kg. The materials include 11.25 kg of metallic chromium, 0.50 kg of nickel bars, 1.90 kg of titanium rods, 1.00 kg of high-purity aluminum, 0.02 kg of nickel boron, 9.50 kg of electrolytic cobalt, 1.00 kg of pure tungsten, 0.70 kg of tantalum ingots, 0.05 kg of metallic zirconium, 23.325 kg of nickel plates, 0.60 kg of nickel-lanthanum alloy, 0.08 kg of nickel-yttrium alloy and 0.075 kg of carbon raiser. The six easily burnable elements, titanium rods, high-purity aluminum, nickel boron, metallic zirconium, nickel-lanthanum alloy and nickel-yttrium alloy, are added during the secondary feeding process. The remaining raw materials are filled into the melting crucible before melting, and are placed according to the principle of being dense at the bottom and loose in the middle and upper parts to prevent bridging during melting. (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and proceed to the next step when the vacuum degree is less than 50Pa.

[0029] (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas charging valve, and charge at a pressure of 0.7 MPa. When the furnace pressure reaches 6 × 10⁻⁶ MPa... 4 When the pressure reaches Pa, stop the gas filling process and repeat the above vacuuming and gas replacement steps three times. The furnace pressure is 1×10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protection smelting: Increase the power of the smelting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the smelting crucible at high power and refine it at 1480℃ for 10 minutes, while tilting the crucible 3 times to make the liquid uniform. (5) Inert gas atomization: High-purity argon gas (99.999%) preheated to 100~150°C is used for atomization. When the molten liquid temperature reaches 1560°C, the atomizing gas pressure regulating valve is opened and the pressure is quickly adjusted to 2.5-2.6MPa. At the same time, the molten liquid is poured into the tundish. The molten liquid flows out from the tundish through the guide nozzle with a diameter of 4.5mm at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is crushed, atomized and solidified by high-pressure argon gas into the nickel-based alloy powder. Among them, 6 minutes before pouring the liquid, the six raw materials, namely titanium rod, high-purity aluminum, nickel boron, metallic zirconium, nickel lanthanum alloy and nickel yttrium alloy, are added to the melting crucible through the secondary feeding cylinder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder with a size of 15-45μm.

[0030] The nickel-based alloy powder prepared in this embodiment was used for laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a forming density of 99.55%.

[0031] Example 8 The alloy powder used in this embodiment is the same as that in Example 7, but the process parameters have been further optimized: the superheat is optimized to 140-160°C, and other parameters are the same as in Example 7. This combination of parameters further reduces the hollow powder ratio to <1.5%. The specific preparation process is as follows: (1) Batching and loading: The total weight of the materials is 50 kg. The materials include 11.25 kg of metallic chromium, 0.50 kg of nickel bars, 1.90 kg of titanium rods, 1.00 kg of high-purity aluminum, 0.02 kg of nickel boron, 9.50 kg of electrolytic cobalt, 1.00 kg of pure tungsten, 0.70 kg of tantalum ingots, 0.05 kg of metallic zirconium, 23.325 kg of nickel plates, 0.60 kg of nickel-lanthanum alloy, 0.08 kg of nickel-yttrium alloy and 0.075 kg of carbon raiser. The six easily burnable elements, titanium rods, high-purity aluminum, nickel boron, metallic zirconium, nickel-lanthanum alloy and nickel-yttrium alloy, are added during the secondary feeding process. The remaining raw materials are filled into the melting crucible before melting, and are placed according to the principle of being dense at the bottom and loose in the middle and upper parts to prevent bridging during melting. (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and proceed to the next step when the vacuum degree is less than 50Pa.

[0032] (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas charging valve, and charge at a pressure of 0.7 MPa. When the furnace pressure reaches 6 × 10⁻⁶ MPa... 4When the pressure reaches Pa, stop the gas filling process and repeat the above vacuuming and gas replacement steps three times. The furnace pressure is 1×10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protection smelting: Increase the power of the smelting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the smelting crucible at high power and refine it at 1480℃ for 10 minutes, while tilting the crucible 3 times to make the liquid uniform. (5) Inert gas atomization: High-purity argon gas (99.999%) preheated to 100~150°C is used for atomization. When the molten liquid temperature reaches 1510°C, the atomizing gas pressure regulating valve is opened and the pressure is quickly adjusted to 2.5-2.6MPa. At the same time, the molten liquid is poured into the tundish. The molten liquid flows out from the tundish through the guide nozzle with a diameter of 4.5mm at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is crushed, atomized and solidified by high-pressure argon gas into the nickel-based alloy powder. Among them, 6 minutes before pouring the liquid, the six raw materials, namely titanium rod, high-purity aluminum, nickel boron, metallic zirconium, nickel lanthanum alloy and nickel yttrium alloy, are added to the melting crucible through the secondary feeding cylinder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder with a size of 15-45μm.

[0033] The features of the preparation method in this embodiment compared with the existing gas atomization process are as follows: In step (5): 1. Atomize with high-purity argon gas preheated to 100~150°C; 2. Pour at 1510°C, the melting point of the alloy is 1350°C, and the superheat is 140-160°C (the existing pouring temperature is 1560°C, and the superheat is 190-210°C); 3. Adjust the atomization pressure to 2.5-2.6MPa (the existing parameters are 2.3-2.4MPa); 4. Precise addition of rare earth: In the form of Ni-La and Ni-Y intermediate alloys, add in steps in the later stage of vacuum melting (5-8 minutes before pouring) to avoid oxidation and burn-off, and ensure that the rare earth is evenly distributed and precisely controllable. Compared to traditional processes, this embodiment effectively suppresses gas entrainment during melt fragmentation through synergistic optimization of low superheat control and atomized gas preheating, reducing the generation of hollow powder from the source. The overall powder quality meets the stringent requirements of In939 alloy powder for high-end additive manufacturing. The powder prepared in this embodiment is used for laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a part density of 99.8%.

[0034] The nickel-based alloy powder obtained by the preparation method in this embodiment is as follows: Figure 1 As shown: It exhibits high sphericity, a smooth surface, and relatively few satellite spheres, such as... Figure 2As shown, the internal structure is dense with no obvious hollow defects. Testing revealed that the hollow powder rate was less than 1.5%, and the oxygen content was less than 80 ppm. The flowability and loose packing density of the alloy powder in this embodiment are shown in Table 2, exhibiting good loose packing density and flowability.

[0035] Table 2

[0036] The results of performance testing of the alloy powders obtained in Comparative Example 1 and Examples 1-8 are shown in Table 3.

[0037] Table 3

[0038] As can be seen from the above, compared with Comparative Example 1, Examples 1-8 of the present invention modify the alloy powder with rare earth elements, resulting in significantly improved high-temperature creep resistance and oxidation resistance, and a significant reduction in printing crack sensitivity (room temperature elongation and impact energy are both data characterizing printing hot crack sensitivity: the greater the impact energy, the fewer cracks in the printed part; the higher the elongation rate, the less likely the printed part is to break). Meanwhile, Examples 7-8 of the present invention modify the process compared to the other examples: because the surface tension and viscosity of the melt change after rare earth modification, measures such as reducing superheat and preheating the atomizing gas are used to improve melt flowability, reduce gas entrainment, and achieve a hollow powder rate of <2% and a formed part density of 99.8%.

[0039] The advantages of the nickel-based alloy powder and preparation method of this invention are as follows: 1. La+Y composite modified composition: La content 0.01-0.08wt%, Y content 0.002-0.005wt%, total content 0.012-0.085wt%. Y microalloying purifies grain boundaries, reduces brittle phases at grain boundaries, improves wettability, increases room temperature elongation from 8-10% to 14-16%, and increases impact energy by more than 30%. La modifies the oxide film, improves the density and adhesion of the oxide film, and reduces the oxidation weight gain rate at 900°C by more than 40%. La+Y synergistically improves melt wettability and solidification characteristics, increases grain boundary strength, reduces printing hot crack sensitivity, achieves crack-free forming, and increases creep rupture life at 816°C / 250MPa from 287 hours to 410 hours. 2. Precise rare earth addition process. 1. Ni-La and Ni-Y master alloys are added in stages during the later stages of vacuum melting (5-8 minutes before casting) to avoid oxidation and burn-off, ensuring uniform and precise distribution of rare earth elements. The success rate of rare earth solid solution is increased from <30% to >80%, and the Y content is precisely controlled within the range of 20-50%. 2. Special gas atomization process: superheat 140-160°C, atomization pressure 2.5-2.6MPa, preheated gas 100-150°C, optimized in conjunction with the melt characteristics after rare earth modification, so that rare earth elements are evenly distributed in the matrix, giving full play to their key roles in purifying grain boundaries, improving melt wettability, and inhibiting hot cracks. The hollow powder rate is significantly reduced from 5-10% in traditional processes to <2%, and the density of additively manufactured parts is increased from 99.2% to 99.8%, avoiding fatigue cracks.

[0040] In summary, the alloy powder of this invention is modified by adding rare earth elements and prepared through a process of low superheat, preheated gas, and high atomization pressure. This achieves coordinated optimization with the melt characteristics after rare earth modification, thereby improving grain boundary strength, enhancing oxidation resistance, improving high-temperature creep performance, and reducing the sensitivity to printing hot cracks. It ensures uniform and precise distribution of rare earth elements, reduces the hollow powder rate from 5-10% in traditional processes to <2%, and increases the density of additively manufactured parts from 99.2% to 99.8%.

Claims

1. A nickel-based alloy powder resistant to high-temperature creep, characterized in that: Its chemical composition and percentage (wt%) are as follows: Cr: 22.2-22.8, Nb: 0.9-1.1, Ti: 3.6-3.8, Al: 1.8-2.0, B: 0.004-0.012, Co: 18.5-19.5, W: 1.8-2.2, Ta: 1.3-1.5, Zr: 0.05-0.14, C: 0.13-0.17, La: 0.01-0.08, Y: 0.002-0.005, and the total content of La + Y is 0.012-0.085, with the balance being Ni and unavoidable impurities; the content of P and S elements does not exceed 0.02%.

2. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2%, Nb: 1%, Ti: 3.7%, Al: 1:9%, B: 0.008%, Co: 19%, W: 2%, Ta: 1.4%, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.

004.

3. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.02, Y: 0.

003.

4. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2%, Nb: 1%, Ti: 3.7%, Al: 1:9%, B: 0.008%, Co: 19%, W: 2%, Ta: 1.4%, Zr: 0.1, C: 0.15, La: 0.04, Y: 0.

003.

5. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2%, Nb: 1%, Ti: 3.7%, Al: 1:9%, B: 0.008%, Co: 19%, W: 2%, Ta: 1.4%, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.

003.

6. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2, Nb: 1, Ti: 3.7, Al: 1:9, B: 0.008, Co: 19, W: 2, Ta: 1.4, Zr: 0.1, C: 0.15, La: 0.08, Y: 0.

003.

7. The nickel-based alloy powder according to claim 1, characterized in that: The preferred percentages of the chemical composition are: Cr: 22.2%, Nb: 1%, Ti: 3.7%, Al: 1:9%, B: 0.008%, Co: 19%, W: 2%, Ta: 1.4%, Zr: 0.1, C: 0.15, La: 0.06, Y: 0.

005.

8. A method for preparing nickel-based alloy powder by vacuum atomization according to any one of claims 1-7, comprising the following steps: (1) Batching and loading: Batching is carried out according to the composition ratio of nickel-based alloy powder. The easily burnable elements are added during the secondary feeding process, while the remaining raw materials are filled into the melting crucible before melting, and placed according to the principle of being dense at the bottom and loose in the middle and upper parts. (2) Vacuuming: Adjust the heating power of the intermediate ladle and melting crucible to 18KW, turn on the vacuum pump, and proceed to the next step when the vacuum degree is less than 50Pa; (3) Gas replacement: Turn off the vacuum pump, open the high-purity argon gas charging valve, and charge at a pressure of 0.7 MPa. When the furnace pressure reaches 6 × 10⁻⁶ MPa... 4 When the pressure reaches Pa, stop the gas filling process and repeat the above vacuuming and gas replacement steps three times. The furnace pressure is 1×10⁻⁶ when the last replacement is completed. 5 Pa; (4) Inert gas protection smelting: Increase the power of the smelting crucible, tilt the crucible 3 times during the melting process, and after the raw materials are completely melted into liquid, keep the smelting crucible at high power and refine it at 1480℃ for 10 minutes, while tilting the crucible 3 times to make the liquid uniform. (5) Inert gas atomization: High-purity argon gas (99.999%) preheated to 100-150°C is used for atomization. When the molten liquid temperature reaches 1510°C, the atomizing gas pressure regulating valve is opened and the pressure is quickly adjusted to 2.5-2.6MPa. At the same time, the molten liquid is poured into the tundish. The molten liquid flows out from the tundish through the guide nozzle with a diameter of 4.5mm at the bottom of the composite atomizing spray plate of the annular seam and annular hole. It is crushed, atomized and solidified by high-pressure argon gas into the nickel-based alloy powder. Among them, 5-8 minutes before pouring the liquid, the six raw materials, namely titanium rod, high-purity aluminum, nickel boron, metallic zirconium, nickel lanthanum alloy and nickel yttrium alloy, are added to the melting crucible through the secondary feeding cylinder. (6) Sieving: After the powder is cooled and collected, it is sieved using an air classifier to obtain powder with a size of 15-45μm.

9. The nickel-based alloy powder obtained by the preparation method according to claim 8, characterized in that: it is hollow. The powder content is less than 1.5%, the rare earth solid solution success rate (La) is 85%, the room temperature elongation is 22.1%, the impact energy is 41J, the creep rupture life at 816℃ / 250MPa is 395h, and the oxidation weight gain at 900℃ for 100h isothermal isotherm is 1.14mg / cm³. 3 .

10. The nickel-based alloy powder obtained by the preparation method according to claim 8, characterized in that: It was used in laser powder bed melting (LPBF) additive manufacturing with a laser power of 280W, a scanning speed of 1000mm / s, a layer thickness of 40μm, and a part density of 99.8%.

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