Single-phase nickel-based superalloy powder for additive manufacturing, method of making, and alloy part manufacturing process

Abstract

The application relates to the field of additive manufacturing, and provides a single-phase nickel-based high-temperature alloy powder for additive manufacturing, a preparation method and an alloy part manufacturing process.The preparation method comprises the following steps: S1 alloy component proportioning: adopting a Ni-W-Co ternary system, and the mass percentage of W is 37-39%, the mass percentage of Co is 19-17%, and the mass percentage of Ni is the balance; S2 mother alloy smelting and ingot casting; S3 melt vacuum degassing; S4 high-purity argon atomization into alloy powder; S5 liquid-state low-temperature cooling and alloy powder screening; and S6 vacuum annealing.The alloy part manufacturing comprises the following steps: X1 setting laser selective melting process parameters; X2 layer-by-layer laying of the alloy powder, laser melting, and layer-by-layer cooling to obtain a 3D printing part; and X3 heating of the 3D printing part to 1200 DEG C and water quenching solid solution treatment.The part prepared by the application has a tensile strength of greater than or equal to 160 MPa and an elongation of greater than or equal to 45% under a service condition of 1100 DEG C, and is significantly superior to existing nickel-based alloys.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and in particular to a single-phase nickel-based high-temperature alloy powder for additive manufacturing, its preparation method, and the manufacturing process for alloy parts. Background Technology

[0002] Additive manufacturing (AM) technology has received widespread attention and application in recent years, especially in manufacturing fields with high complexity, high precision, and high customization requirements. Among these, selective laser bed fusion (LPBF), as an important additive manufacturing process, has gradually become one of the key technologies in industrial production due to its advantages such as high speed, high efficiency, and diverse material selection. Nickel-based superalloys are the most widely used and strongest high-temperature alloys. With nickel as the matrix (generally containing more than 50%), nickel-based superalloys exhibit high strength and good resistance to oxidation and gas corrosion in the temperature range of 650–850℃. Different nickel-based superalloys contain more than ten alloying elements, including Cr, Co, W, Mo, Re, Al, Ti, C, B, Zr, and Y. These different elements play roles in strengthening the alloy through solid solution strengthening, second-phase strengthening, and grain boundary strengthening. With the advancement of science and technology and the rapid development of the aerospace industry, nickel-based superalloys have become one of the most widely used blade materials in the aerospace field due to their high strength at high temperatures and good resistance to oxidation and gas corrosion.

[0003] When used as high-temperature resistant materials in national defense and scientific research, high-temperature alloys are subjected to different extreme environments in different working parts, especially under extremely high temperatures, with operating temperatures exceeding 1000℃. Therefore, providing nickel-based high-temperature alloys with superior performance above 1000℃ is particularly important. However, in traditional gas atomization powder preparation processes, the oxygen content of the powder is generally higher than 100ppm, which easily leads to grain boundary oxidation and embrittlement at high temperatures. For example, the oxygen content of existing Haynes 230 alloy gas atomized powder is ≥100ppm, and the oxidation rate is ≥0.2g / m³. 2 h leads to grain boundary catalysis, ultimately resulting in high-temperature oxidation failure. Therefore, nickel-based superalloys that can satisfy the synergistic effect of strong plasticity above 1000℃ still have some problems to be solved in practical applications.

[0004] To improve the overall performance of the forming process for complex structural components in national defense science and technology, developing a high-temperature environment that can operate at 1100℃ and meet the balance between strength and plasticity has become an urgent technical challenge.

[0005] This invention achieves a breakthrough by employing a four-stage oxygen control process: melt vacuum degassing, dynamic protection with high-purity argon, low-temperature fluidized bed cooling, and vacuum annealing. This process results in an oxygen content ≤50ppm and an oxidation rate ≤0.05g / m³. 2 h significantly improves the high-temperature lifespan of the alloy. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a single-phase nickel-based high-temperature alloy powder for additive manufacturing, its preparation method, and the manufacturing process for alloy parts. Through alloy composition design and a four-stage oxygen control process—melt vacuum degassing + high-purity argon dynamic protection + low-temperature fluidized bed cooling + vacuum annealing—a breakthrough is achieved, resulting in an alloy oxygen content ≤50ppm and an oxidation rate ≤0.05g / m³. 2 h, with a service temperature up to 1100℃, significantly improving the high-temperature life of the alloy.

[0007] The present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a method for preparing single-phase nickel-based superalloy powder for additive manufacturing, comprising:

[0009] S1. Alloy composition ratio: The Ni-W-Co ternary system is adopted, and the alloy composition is 37-39% W, 19-17% Co, and the balance is Ni by mass percentage.

[0010] S2. Master alloy melting and casting: The proportioned alloying elements are placed into a heating container in sequence, melted into a master alloy melt with uniform composition, and cooled to obtain an ingot.

[0011] S3. Vacuum degassing: The ingot is heated into a melt and then vacuum degassed so that the oxygen content of the melt is lower than a set threshold.

[0012] S4. High-purity argon atomization: The melt obtained by high-purity argon high-speed blowing step S3 is atomized into alloy powder;

[0013] S5. Liquid-state cryogenic cooling: The atomized alloy powder is placed in an air jet mill for surface treatment, and the liquid-state argon gas is circulated for cooling to improve the morphology of the alloy powder. The alloy powder is then sieved in high-purity argon gas.

[0014] S6. Vacuum annealing: Vacuum annealing is performed on the alloy powder after sieving to remove adsorbed oxygen and obtain low-oxygen spherical single-phase nickel-based high-temperature alloy powder with an oxygen content ≤50ppm, smooth surface and no satellite powder.

[0015] In addition to any of the possible implementations described above, a further implementation is provided in which, in step S2, a vacuum induction melting process is used for staged melting. After preheating the crucible to 1455±10℃, pure Ni is placed in the crucible, and the temperature is further increased to 1500±10℃. After the pure Ni melts, pure Co is pressed into the crucible. The process involves three vacuum melting processes and electromagnetic stirring, with stirring for 30 minutes. After the stirring is uniform, the melt temperature is raised to 3422±10℃, pure W is added, and stirring is performed for 30 minutes. After melting, a master alloy melt with uniform composition is obtained, ensuring that the compositional uniformity deviation of the master alloy melt is ≤0.5%.

[0016] In addition to any of the possible implementations described above, another implementation is provided in which, in step S3, the melt is kept at a vacuum of ≤1×10-3Pa for 30 minutes, and the gas is promoted to float out by electromagnetic stirring, so that the oxygen content of the melt is reduced to ≤80ppm.

[0017] In addition to any of the possible implementations described above, another implementation is provided in which, in step S4, the vacuum degree is ≤5×10 -3 Under Pa conditions, the valve at the bottom of the crucible is opened, and the melt flows out through a guide tube with an inner diameter of 3.5 mm, falling freely. During this process, the powder spraying temperature is 1670℃. High-purity argon gas with a purity of ≥99.99% is dynamically introduced into the atomization chamber at a flow rate of 5-8 L / min to maintain an oxygen partial pressure ≤5 Pa. The atomization is then impacted and atomized into fine droplets at a high pressure of 10 MPa (atomization pressure fluctuation ≤0.5 MPa) and a spray angle of 30-45°, forming alloy powder with a particle size of 15-53 μm, sphericity ≥95%, void fraction <0.1%, and oxygen content ≤200 ppm.

[0018] In addition to any of the possible implementations described above, a further implementation is provided in which, in step S5, the alloy powder obtained by gas atomization is placed in an air jet mill for surface treatment, cooled by fluidized argon circulation at a cooling rate ≥100℃ / s until below 200℃, with a gas pressure of 0.2~1.0MPa and a treatment time of 30±10min, thereby improving the morphology of the alloy powder. The fine powder yield is ≥85%, and the powder surface roughness Ra≤5μm.

[0019] On the other hand, the present invention provides a single-phase nickel-based superalloy powder for additive manufacturing, wherein the alloy powder is obtained by the above-described method for preparing single-phase nickel-based superalloy powder for additive manufacturing.

[0020] In addition to any of the possible implementations described above, another implementation is provided in which the alloy powder is composed of 37% W, 19% Co, and 44% Ni by mass percentage.

[0021] On the other hand, the present invention also provides an additive manufacturing process for high-temperature nickel-based alloy parts, the process using the above-mentioned single-phase nickel-based high-temperature alloy powder, the process comprising:

[0022] X1. Set the laser selective melting process parameters;

[0023] X2. Single-phase nickel-based high-temperature alloy powder is laid in layers, melted by laser, and cooled layer by layer to obtain 3D printed parts with a density ≥99.5%;

[0024] X3. The 3D printed part is heated to 1200℃ and subjected to water quenching and solution treatment to promote the homogenization of the single-phase FCC structure and eliminate the brittle phase at grain boundaries and the second phase.

[0025] In addition to any of the possible implementations described above, another implementation is provided in which energy input, scanning speed, layer thickness and cooling rate are optimized during LPBF additive manufacturing printing to achieve the required grain refinement and residual stress control, thereby improving high-temperature tensile properties and ductility.

[0026] In addition to any of the possible implementations described above, another implementation is provided in which the process parameters in step X1 are: laser power 150-170W, scanning speed 180-300mm / s, layer thickness 30μm, and interlayer cooling rate ≥10. 5 K / s.

[0027] In addition to any of the possible implementations described above, a further implementation is provided in which the prepared high-temperature nickel-based alloy part has a single-phase FCC structure, and under service conditions of 1100℃, has a tensile strength ≥160MPa, an elongation ≥45%, a high-temperature creep life ≥300h (1100℃ / 200MPa), and an oxidation weight gain ≤0.5mg / cm³. 2 (1100℃ / 100h).

[0028] High-tungsten nickel-based superalloys prepared by traditional processes (casting, forging, powder metallurgy, etc.) have a maximum solid solubility of W in Ni of only 15 at.%, and are accompanied by a large number of intermetallic compounds that seriously affect the alloy properties.

[0029] This invention employs composition design and high-throughput screening of alloys: based on thermodynamic calculations using a Ni-W-Co ternary isothermal phase diagram, the solid solubility window of W in the Ni matrix is ​​determined to be 37-39%; elemental Ni, W, and Co powders are mixed using mechanical ball milling, and a gradient composition design (Ni-Co-35W, Ni-Co-37W, Ni-Co-39W) combined with high-temperature oxidation resistance testing (weight gain ≤0.5 mg / cm³ at 1100℃ / 100h) is implemented. 2 ) and mechanical performance evaluation to select the optimal component ratio;

[0030] Based on the ingredient design, a four-stage deoxygenation process is adopted:

[0031] 1. Vacuum degassing of melt: After multiple melting processes, the alloy melt is held at a vacuum of ≤1×10-3Pa for 30 minutes. The gas is then stirred by electromagnetic stirring (frequency 25Hz) to promote its upward escape, thereby reducing the oxygen content of the melt from the initial 120ppm to ≤80ppm.

[0032] 2. High-purity argon atomization: After the alloy melt is melted, it is atomized under a vacuum degree ≤5×10 -3 Under Pa conditions, the valve at the bottom of the crucible is opened, and the alloy melt flows out through a guide tube with an inner diameter of 3.5 mm and falls freely. During this process, the powder spraying temperature is 1670℃. High-purity argon gas with a purity of ≥99.99% is dynamically introduced into the atomization chamber at a flow rate of 5-8 L / min to maintain an oxygen partial pressure ≤5 Pa. The gas is then impacted and atomized at a high pressure of 10 MPa and a spray angle of 30-45° to break it into fine droplets, forming alloy powder with a particle size of 15-53 μm, sphericity ≥95%, void ratio <0.1%, and oxygen content ≤200 ppm.

[0033] 3. Fluidized low-temperature cooling: The metal powder obtained by gas atomization is placed in an air jet mill for surface treatment. Fluidized argon gas is circulated and cooled (cooling rate ≥100℃ / s) to below 200℃. The gas pressure is 0.2~1.0MPa, the rotation speed is 1500~3000r / min, and the treatment time is 30±10min. Finally, the atomized metal powder with improved powder surface morphology is placed in high-purity argon gas for sieving.

[0034] 4. Vacuum annealing: The sieved powder is placed in a vacuum annealing furnace (800℃ / 2h, vacuum degree ≤5×10-3Pa) to remove adsorbed oxygen, and finally low-oxygen spherical powder with oxygen content ≤50ppm, smooth surface and no satellite powder is obtained.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. The Ni-W-Co ternary system was adopted. Through a large number of experiments, the inventors found that if other elements are added to the Ni-W-Co ternary system, a multiphase structure with precipitated phases and other harmful phases is easily formed, instead of a solid solution phase FCC single-phase structure, which in turn affects the high-temperature performance of the alloy.

[0037] 2. Single-phase eutectic alloys with high W solid solubility are designed through materials genome engineering. The amount of W added should be appropriate and should not exceed its solubility limit. Otherwise, it will increase the tendency of harmful phases such as second phase (μ, TCP) to precipitate, and at the same time reduce the high-temperature oxidation and corrosion resistance of the alloy.

[0038] 3. By optimizing the Ni, W, and Co composition ratio through high-throughput preparation, the mechanical strength of the sample was significantly improved, and the formation of the second phase was suppressed.

[0039] 4. Through a four-stage oxygen control technology—melt vacuum degassing, high-purity argon atomization, fluidized bed cryogenic cooling, and vacuum annealing—the oxygen content of the powder is reduced from ≥100ppm in traditional processes to ≤50ppm, grain boundary oxygen segregation is reduced by 70%, and the high-temperature oxidation rate of the alloy at 1100℃ is reduced to ≤0.05g / m³. 2 •h, significantly better than similar materials (e.g., Haynes 230 alloy oxidation rate ≥0.2g / m). 2 ·h).

[0040] 5. The prepared single-phase FCC nickel-based eutectic alloy has the innovative characteristics of high strength and high ductility under the premise of high tungsten content, which solves the cracking problem in the preparation of traditional high-tungsten content high-temperature alloys (GH3536, GH3230).

[0041] 6. Subsequent heat treatment processes (solution treatment) further adjust the microstructure to improve the overall mechanical properties of the material under high-temperature conditions.

[0042] 7. The present invention rationally designs the additive manufacturing process to ensure that the microstructure of the final prepared novel high-temperature alloy complex parts is uniform and meets the performance requirements under high-temperature conditions.

[0043] 8. Physical properties of alloy parts: tensile strength ≥160MPa (1100℃), elongation ≥45% (1100℃), high-temperature creep life ≥300h (1100℃ / 200MPa), oxidation weight gain ≤0.5mg / cm³ 2 (1100℃ / 100h). Attached Figure Description

[0044] Figure 1 The diagram shown is a schematic flow chart of a method for preparing single-phase nickel-based superalloy powder for additive manufacturing according to an embodiment of the present invention.

[0045] Figure 2 The diagram shown is a schematic flow chart of an additive manufacturing process for a high-temperature nickel-based alloy part according to an embodiment of the present invention.

[0046] Figure 3 The following is a schematic diagram of the alloy powder preparation process in the embodiment: (a) is the master alloy ingot; (b) is the gas atomization powder preparation; (c) is the scanning electron microscope image of the alloy powder.

[0047] Figure 4 The image shown is a physical picture of the alloy part prepared by the laser selective melting process in the embodiment. Detailed Implementation

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0049] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for preparing single-phase nickel-based superalloy powder for additive manufacturing, comprising:

[0050] S1, Alloy Composition Ratio Design

[0051] Nickel-based superalloys are the most widely used and strongest type of superalloy at high temperatures. With nickel as the base metal, nickel-based superalloys exhibit high strength and good resistance to oxidation and gas corrosion in the 650–1000℃ range, making them widely used in the aerospace field. Nickel-based superalloys typically contain more than ten alloying elements, including Cr, Co, W, Mo, Al, and Ti. These different elements contribute to the strengthening of the alloy through solid solution strengthening, second-phase strengthening, and grain boundary strengthening.

[0052] Ni: Nickel has a face-centered cubic structure and does not undergo allotropic transformation. The face-centered cubic austenitic matrix exhibits higher stability and high-temperature strength at high temperatures due to its higher self-diffusion activation energy and lower atomic diffusion ability. Simultaneously, Ni possesses high chemical stability, hardly oxidizing below 500℃ and is not easily corroded by water, moisture, or certain salt solutions at room temperature. Furthermore, the Ni matrix can dissolve more alloying elements without forming harmful phases.

[0053] Tungsten (W): Tungsten has a high solubility in nickel (1500℃), which can improve the interatomic bonding force, increase the diffusion activation energy, and slow down the diffusion process. It also raises the recrystallization temperature, improves the alloy's thermal strength, and produces a significant solid solution strengthening effect. Furthermore, the addition of W can increase the melting point of the base alloy. However, the amount of W added must be appropriate and should not exceed its solubility limit; otherwise, it will increase the tendency for harmful phases such as the alloy phase and μ phase to precipitate, and will also reduce the alloy's high-temperature oxidation and corrosion resistance.

[0054] Co: In nickel-based alloys, cobalt is mostly dissolved in the matrix, with a small amount entering the γ′ phase. Co's entry into the matrix produces a solid solution strengthening effect. Co can reduce the stacking fault energy of the matrix, and since the creep rate of an alloy is proportional to the nth power of the stacking fault energy, Co can reduce the creep rate of nickel-based alloys. Furthermore, Co can improve the hot working properties, plasticity, and impact toughness of nickel-based alloys.

[0055] To ensure that the novel high-temperature alloy possesses a single-phase microstructure (FCC), ternary isothermal phase diagrams at 1000℃, 1200℃, 1400℃, and 1600℃ were selected to obtain the eutectic composition range. Samples were then prepared using high-throughput mixing of elemental powders to determine the optimal performance composition ratios. The specific compositions are shown in Table 1 below.

[0056] Table 1. Composition Design of Novel High-Temperature Alloys (wt.%)

[0057] content margin 37～39％ 19-16％ 0.00048

[0058] S2. Master alloy melting and casting: The proportioned alloying elements are placed into a heating container in sequence, melted into a master alloy melt with uniform composition, and cooled to obtain an ingot.

[0059] S3. Vacuum degassing: The ingot is heated into a melt and then vacuum degassed so that the oxygen content of the melt is lower than a set threshold.

[0060] S4. High-purity argon atomization: The melt obtained by high-purity argon high-speed blowing step S3 is atomized into alloy powder;

[0061] S5. Liquid-state cryogenic cooling: The atomized alloy powder is placed in an air jet mill for surface treatment, and the liquid-state argon gas is circulated for cooling to improve the morphology of the alloy powder. The alloy powder is then sieved in high-purity argon gas.

[0062] S6. Vacuum annealing: Vacuum annealing is performed on the alloy powder after sieving to remove adsorbed oxygen and obtain low-oxygen spherical single-phase nickel-based high-temperature alloy powder with an oxygen content ≤50ppm, smooth surface and no satellite powder.

[0063] In one specific embodiment, in step S2, a vacuum induction melting process is used for staged melting. After preheating the crucible to 1455±10℃, pure Ni is placed in the crucible, and the temperature is further increased to 1500±10℃. After the pure Ni melts, pure Co is pressed into the crucible. The process involves three vacuum melting processes and electromagnetic stirring, with stirring for 30 minutes. After the stirring is uniform, the melt temperature is raised to 3422±10℃, pure W is added, and stirring is performed for 30 minutes. After melting, a master alloy melt with uniform composition is obtained, ensuring that the compositional uniformity deviation of the master alloy melt is ≤0.5%.

[0064] In one specific embodiment, in step S3, the melt is kept at a vacuum of ≤1×10-3Pa for 30 minutes, and the gas is promoted to float out by electromagnetic stirring, so that the oxygen content of the melt is reduced to ≤80ppm.

[0065] In one specific embodiment, in step S4, when the vacuum degree is ≤5×10 -3Under Pa conditions, the valve at the bottom of the crucible is opened, and the melt flows out through a guide tube with an inner diameter of 3.5 mm, falling freely. During this process, the powder spraying temperature is 1670℃. High-purity argon gas with a purity of ≥99.99% is dynamically introduced into the atomization chamber at a flow rate of 5-8 L / min to maintain an oxygen partial pressure ≤5 Pa. The gas is then impacted and atomized into fine droplets at a high pressure of 10 MPa and a spray angle of 30-45°, forming alloy powder with a particle size of 15-53 μm, sphericity ≥95%, void ratio <0.1%, and oxygen content ≤200 ppm.

[0066] In one specific embodiment, in step S5, the alloy powder obtained by gas atomization is placed in an air jet mill for surface treatment, and fluidized argon gas is circulated for cooling at a cooling rate of ≥100℃ / s until below 200℃. The gas pressure is 0.2~1.0MPa, and the treatment time is 30±10min, thereby improving the morphology of the alloy powder.

[0067] In one specific embodiment, cast rods of the same composition are first prepared, and then powdered.

[0068] Rod preparation:

[0069] First, prepare the required elements for the nickel alloy according to the design composition shown in Table 1. Then, place the prepared materials into a vacuum melting furnace for melting. After melting, hold the master alloy melt at a vacuum degree ≤1×10-3 Pa for 30 minutes. Use electromagnetic stirring (frequency 25Hz) to promote gas flotation and escape, reducing the oxygen content of the melt from the initial 120ppm to ≤80ppm. Cast into solid bars as shown in Table 1. Figure 3 As shown in (a).

[0070] Powder preparation:

[0071] The rod is placed in a vacuum atomization powder-making device for atomization powder production, such as... Figure 3 As shown in (b), the atomization chamber is pre-evacuated to ≤5×10⁻³ Pa, and then filled with dynamic high-purity argon gas (flow rate 5 L / min) to maintain an oxygen partial pressure ≤5 Pa. This step stabilizes the atomization of the gas-atomized powder and reduces hollow powder. The resulting melt is introduced into an atomization furnace for gas atomization treatment using an M18 crucible. A guide tube with a diameter of 3.5 mm and a length of 15.7 mm is used for gas atomization treatment. The atomization temperature is 1670℃ above the liquidus temperature. The injection speed for gas atomization treatment is controlled at 2 kg / min. The vacuum degree inside the gas atomization furnace is controlled at 4.6×10⁻³ Pa. -3 Pa; the pressure of the high-pressure atomizing medium is controlled at 10 MPa; nickel alloy powder is produced by vacuum inert gas atomization technology, the cooled powder is taken out, and the powder is sieved and graded by a vibrating sieve device, with upper and lower limits of 15 micrometers and 53 micrometers respectively. After sieving, nickel-based alloy powder with a particle size of 15-53 micrometers is obtained. Figure 3As shown in (c), the yield of fine powder is guaranteed.

[0072] Deoxidation treatment: After atomization, the powder is cooled by fluidized argon circulation (cooling rate ≥100℃ / s) to below 200℃ to inhibit the growth of surface oxide film. The sieved powder is then subjected to vacuum annealing furnace (800℃ / 2h, vacuum degree ≤5×10-3Pa) to remove adsorbed oxygen, with the final oxygen content ≤50ppm.

[0073] This invention provides a single-phase nickel-based high-temperature alloy powder for additive manufacturing, which is obtained by the above-described preparation method for single-phase nickel-based high-temperature alloy powder for additive manufacturing.

[0074] In one specific embodiment, the alloy powder is composed of 37% W, 19% Co, and 44% Ni by mass percentage, which is the optimal ratio obtained through optimization.

[0075] like Figure 2 As shown in the figure, an additive manufacturing process for a high-temperature nickel-based alloy part according to an embodiment of the present invention is provided. The process uses the above-mentioned single-phase nickel-based high-temperature alloy powder, and the process includes:

[0076] X1. Set the laser selective melting process parameters;

[0077] X2. Single-phase nickel-based high-temperature alloy powder is layered, laser-melted, and cooled layer by layer to obtain 3D printed parts with a density ≥99.5%. (The text abruptly ends here, so the translation stops as well.) Figure 4 As shown;

[0078] X3. The 3D printed part is heated to 1200℃ and subjected to water quenching and solution treatment to promote the homogenization of the single-phase FCC structure and eliminate the brittle phase at grain boundaries and the second phase.

[0079] In one specific embodiment, in step X1, the process parameters are: laser power 150-170W, scanning speed 180-300mm / s, layer thickness 30μm, and interlayer cooling rate ≥10. 5 K / s.

[0080] The high-temperature nickel-based alloy parts prepared by this invention have a single-phase FCC structure, and under service conditions of 1100℃, the tensile strength is ≥160MPa, the elongation is ≥45%, and the high-temperature creep life is ≥300h.

[0081] Example 1

[0082] In this embodiment, the alloy composition is 37% W, 19% Co, and 44% Ni by mass percentage.

[0083] Complex part forming based on laser melting additive manufacturing:

[0084] The prepared powder was sieved, and a novel high-temperature alloy powder with a diameter of 15-53 μm was selected for additive manufacturing. The reason for selecting powder in this diameter range is that the nickel-based alloy powder with a smaller particle size allows for sufficient heating during the additive manufacturing of the alloy powder, resulting in a finer microstructure and avoiding defects caused by insufficient melting. However, the particle size should not be too small, otherwise powder agglomeration may occur, which will have a negative impact on the powder bulk density, powder flowability and final alloy density.

[0085] Novel high-temperature alloy blocks (such as alloy powders) are prepared by selective laser melting (SLM). Figure 4 As shown in the figure, the selected spot diameter is 90-100μm, the laser power is 125-175W, and the scanning speed is 400-700mm / s. This, combined with the melting conditions of the aforementioned particle size, ensures that the powder is fully melted while also ensuring heat dissipation of the molten pool.

[0086] With a scanning spacing of 90–110 μm and a layer thickness of 25–35 μm, bulk samples were obtained by additive manufacturing on the substrate. The final optimal parameter data are shown in Table 2.

[0087] Table 2 Process parameters for selective laser melting (SLM) additive manufacturing

[0088] Powder particle size range (µm) 15-53 Spot diameter (µm) 100 Layer thickness (µm) 30 Scanning speed (mm / s) 500 Laser power (W) 150

[0089] Example 2

[0090] In this embodiment, the alloy composition is 38% W, 19% Co, and 43% Ni by mass percentage.

[0091] The alloy powder preparation process parameters and laser selective melting process parameters are the same as those in Example 1.

[0092] Example 3

[0093] In this embodiment, the alloy composition is 39% W, 18% Co, and 43% Ni by mass percentage.

[0094] The alloy powder preparation process parameters and laser selective melting process parameters are the same as those in Example 1.

[0095] Example 4

[0096] In this embodiment, the alloy composition is 39% W, 17% Co, and 44% Ni by mass percentage.

[0097] The alloy powder preparation process parameters and laser selective melting process parameters are the same as those in Example 1.

[0098] Performance Analysis

[0099] According to the national standard for tensile testing, the block was prepared into tensile test samples conforming to the national standard, and tensile tests were conducted. The experimental performance comparison showed that NiWCo material outperformed Haynes 230 at extreme high temperatures. Table 3 shows the experimental results:

[0100] Table 3. Composition and performance test results of the novel high-temperature alloy in the 1100℃ example.

[0101] Example 1 44 37 19 yes ≥160MPa ≥150MPa ≥45％ Example 2 43 38 19 yes ≥160MPa ≥150MPa ≥45％ Example 3 43 39 18 yes ≥160MPa ≥150MPa ≥45％ Example 4 44 39 17 yes ≥160MPa ≥150MPa ≥45％

[0102] Table 4. Performance Comparison of Haynes 230 at 1000℃:

[0103] ＞50 13 ＜5 yes - ≤150MPa ≤15％

[0104] The comparison shows that the alloy parts prepared by this invention have significantly improved performance under high-temperature service conditions.

[0105] While several embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to these embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A method for preparing single-phase nickel-based superalloy powder for additive manufacturing, characterized in that, The method includes: S1. Alloy composition ratio: The Ni-W-Co ternary system is adopted, and the alloy composition is 37-39% W, 19-17% Co, and the balance is Ni by mass percentage. S2. Master alloy melting and casting: The proportioned alloying elements are placed into a heating container in sequence, melted into a master alloy melt with uniform composition, and cooled to obtain an ingot. S3. Vacuum degassing: The ingot is heated into a melt and kept at a vacuum of ≤1×10-3Pa for 30 minutes. The gas is promoted to float out by electromagnetic stirring, so that the oxygen content of the melt is reduced to ≤80ppm. S4. High-purity argon atomization: Under a vacuum of ≤5×10-3Pa, the valve at the bottom of the crucible is opened, and the melt flows out through a guide tube with an inner diameter of 3.5mm. During this process, the powder spraying temperature is 1670℃. High-purity argon gas with a purity of ≥99.99% is dynamically introduced into the atomization chamber at a flow rate of 5-8L / min to maintain an oxygen partial pressure of ≤5Pa. The atomization is carried out at a high pressure of 10MPa and a spray angle of 30-45° to form alloy powder with a particle size of 15-53μm, sphericity ≥95%, void ratio <0.1%, and oxygen content ≤200ppm. S5. Liquid-state cryogenic cooling: The atomized alloy powder is placed in an air jet mill for surface treatment. It is cooled by fluidized argon circulation at a cooling rate of ≥100°C / s until it reaches below 200°C. The gas pressure is 0.2~1.0MPa and the treatment time is 30±10min to improve the morphology of the alloy powder. The alloy powder is then sieved in high-purity argon. S6. Vacuum annealing: Vacuum annealing is performed on the alloy powder after sieving to remove adsorbed oxygen and obtain low-oxygen spherical single-phase nickel-based high-temperature alloy powder with oxygen content ≤50 ppm, smooth surface and no satellite powder. Steps S3 to S6 constitute a continuous four-stage oxygen control process, and the alloy powder is suitable for laser selective melting additive manufacturing.

2. The method for preparing single-phase nickel-based superalloy powder for additive manufacturing as described in claim 1, characterized in that, In step S2, a vacuum induction melting process is used for staged melting. After preheating the crucible to 1455±10℃, pure Ni is placed in the crucible, and the temperature is further increased to 1500±10℃. After the pure Ni melts, pure Co is pressed into the crucible. The process involves three vacuum melting processes and electromagnetic stirring, with stirring for 30 minutes. After the stirring is uniform, the melt temperature is raised to 3422±10℃, pure W is added, and stirring is carried out for 30 minutes. After melting, a master alloy melt with uniform composition is obtained, ensuring that the compositional uniformity deviation of the master alloy melt is ≤0.5%.

3. The method for preparing single-phase nickel-based superalloy powder for additive manufacturing as described in claim 1, characterized in that, In step S5, the fine powder yield is ≥85%, and the powder surface roughness Ra≤5μm.

4. A single-phase nickel-based superalloy powder for additive manufacturing, characterized in that, The alloy powder is obtained by the preparation method of single-phase nickel-based high-temperature alloy powder for additive manufacturing as described in any one of claims 1-3.

5. The single-phase nickel-based superalloy powder for additive manufacturing as described in claim 4, characterized in that, The alloy powder is composed of 37% W, 19% Co, and 44% Ni by mass percentage.

6. An additive manufacturing process for high-temperature nickel-based alloy parts, characterized in that, The process uses the single-phase nickel-based superalloy powder as described in claim 4, and the process includes: X1. Set the laser selective melting process parameters; X2. Single-phase nickel-based high-temperature alloy powder is laid in layers, melted by laser, and cooled layer by layer to obtain 3D printed parts with a density ≥99.5%; X3. The 3D printed part is heated to 1200℃ and subjected to water quenching and solution treatment to promote the homogenization of the single-phase FCC structure and eliminate the brittle phase at grain boundaries and the second phase.

7. The additive manufacturing process for high-temperature nickel-based alloy parts as described in claim 6, characterized in that, In step X1, the process parameters are: laser power 150-170 W, scanning speed 180-300 mm / s, layer thickness 30 μm, and interlayer cooling rate ≥10. 5 K / s.

8. The additive manufacturing process for high-temperature nickel-based alloy parts as described in claim 6, characterized in that, The prepared high-temperature nickel-based alloy parts have a single-phase FCC structure and, under service conditions of 1100℃, have a tensile strength ≥160MPa, an elongation ≥45%, and a high-temperature creep life ≥300 h.

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