An oxide dispersion strengthened nickel-based alloy, a method of making and using the same

Abstract

This invention belongs to the field of metallic structural materials, specifically relating to an oxide dispersion-strengthened nickel-based alloy and its preparation method. The alloy composition, by weight percentage, is as follows: Mo: 16.5–18.0%, Cr: 6.5–7.5%, Fe: 3.8–4.5%, C: 0.01–0.045%, Mn: 0.4–1.0%, Si: 0.35–0.5%, Y₂O₃: 0.3–0.7%, Nb: 0.3–0.5%, Ti: 0–0.3%, S: 0–0.002%, P: 0–0.005%, N: 0–0.03%, O: 0–0.2%, with Ni as the balance. The preparation method comprises: gas atomization powder spraying – ball milling – encapsulation and degassing – hot isostatic pressing solidification – forging – heat treatment. Y₂O₃ powder is added during ball milling. By controlling process parameters such as the ball-to-powder ratio, rotation speed, and milling time, the Y₂O₃ powder is dispersed in the nickel-based superalloy powder, achieving alloying. Subsequent hot isostatic pressing (HIP) solidification yields the alloy ingot. Nanoscale Y₂O₃ is used to pin the grain boundaries, ensuring grain boundary stability. The interface between Y₂O₃ and the matrix is ​​utilized to enhance its resistance to neutron radiation.

Description

Technical Field

[0001] This invention belongs to the field of metallic structural materials, specifically relating to an oxide dispersion-strengthened nickel-based alloy and its preparation method. Background Technology

[0002] Thorium-based molten salt reactors are fourth-generation advanced nuclear energy systems that use high-temperature molten salt as a coolant. They are internationally recognized as the most suitable reactor type for the nuclear energy utilization of thorium resources. The development of thorium-based molten salt reactors can provide core technological support and feasible solutions for my country's future large-scale development and utilization of thorium resources and the development of fourth-generation advanced nuclear energy systems. Due to the harsh internal environment of thorium-based molten salt reactors, structural materials, in addition to being subjected to high temperatures, stress, and corrosion from molten fluoride salts during service, are also subjected to intense neutron radiation in some areas. Therefore, improving the neutron radiation resistance of structural alloys is crucial for the long-term service of core components in molten salt reactors.

[0003] Currently, the main structural materials for thorium-based molten salt reactors are nickel-based superalloys with high Mo content. However, their resistance to neutron irradiation remains insufficient, and their long-term service performance in the core region with high temperature and high neutron flux still needs improvement. Oxide dispersion strengthening can further improve the high-temperature strength and neutron irradiation resistance of materials and is one of the main methods for strengthening nuclear materials. Introducing dispersed nano-oxides into nickel-based alloys allows the interface between the oxides and the matrix to absorb helium generated by elemental transmutation after neutron irradiation, absorbing helium bubbles and inhibiting material embrittlement. Simultaneously, the dispersed oxides can hinder dislocation movement, improving the high-temperature strength of the alloy. Based on this, this invention proposes a novel nickel-based alloy that is resistant to high temperatures, radiation, and molten salt corrosion. Summary of the Invention

[0004] The purpose of this invention is to provide an oxide dispersion-strengthened nickel-based alloy and its preparation method. Based on the characteristic that the oxide is dispersed in the nickel-based alloy matrix, the material not only has high strength, but also good resistance to neutron irradiation.

[0005] The technical solution of this invention is: An oxide dispersion-strengthened nickel-based alloy, characterized in that it comprises a master alloy and an oxide dispersion phase dispersed therein. The master alloy composition, by weight percentage, is as follows: Mo: 16.5–18.0%, Cr: 6.5–7.5%, Fe: 3.8–4.5%, C: 0.01–0.045%, Mn: 0.4–1.0%, Si: 0.35–0.5%, Nb: 0.3–0.5%, Ti: 0–0.3%, S: 0–0.002%, P: 0–0.005%, N: 0–0.03%, O: 0–0.2%, Ni balance; the oxide dispersion phase is Y₂O₃, added at 0.3–0.7% (preferably 0.4–0.6%) of the master alloy mass.

[0006] An oxide dispersion-strengthened nickel-based alloy is characterized by: a continuous fine-grained matrix with discontinuous coarse-grained distribution within the fine-grained matrix; the coarse-grained volume accounting for 30-50% of the total volume; the grain size of the coarse-grained region being 5-50 μm; the grain size of the fine-grained region being 50-500 nm; and Y₂O₃ being uniformly dispersed in the fine grains with a number density of 10. 21 ~10 23 / m 3 The size is 10-50nm.

[0007] A method for preparing an oxide dispersion-strengthened nickel-based alloy, characterized in that: The preparation of this alloy includes the following steps: (1) Atomization powder production of master alloy: The master alloy ingot is first smelted and then sprayed with gas atomization powder, or the master alloy powder with the required composition is obtained by direct gas atomization powder spraying; the gas atomization powder spraying parameters are: atomization gas pressure 3.5~4.2MPa (preferably 3.8-4.1MPa), superheat 200~300℃ (preferably 200-240℃), and the protective atmosphere is argon with a volume purity of 99.99% or higher to ensure that the powder particle size is <75μm; (2) Ball milling: Y2O3 powder with a particle size of 30-50 nm was selected and ball-milled with the master alloy atomized powder in the required amount. The process parameters were as follows: the ball milling atmosphere was argon gas with a volume purity of 99.99% or higher; the grinding balls were 304 stainless steel balls; the mass ratio of grinding balls was Φ5mm:Φ8mm:Φ10mm = 4-6: 2.5-3.5:1.5-2.5; the mass ratio of balls to material was 8-12:1; the ball milling time was 40-70 h; the rotation speed was 120-150 r / min; and the particle size range of the powder obtained after ball milling was 10-300 μm. After sieving, powders with different particle size ranges were obtained. During the ball milling process, the Y2O3 powder was fully dispersed in the nickel-based alloy powder to achieve alloying. (3) Encapsulation and vacuuming: In order to remove the gas adsorbed on the surface of the powder particles and improve the density, the powder is encapsulated and vacuumed before welding and sealing. The encapsulation material is low carbon steel or 304 stainless steel, and the shape is a hollow, sealed cylinder or square with a wall thickness of 2.5-3 mm. The particle size of the powder encapsulated is 10-300 μm (preferably 10-100 μm), and the powder accounts for >95% of the encapsulation volume. The vacuuming parameters of the encapsulation are: vacuum pressure ≤10 -2 Pa, temperature 300~500℃, time 6~8h, after evacuation of the casing, weld and seal.

[0008] (4) Hot isostatic pressing curing molding: The sleeve after degassing and sealing is cured by hot isostatic pressing molding. The process is as follows: pressure is 120-180MPa, temperature is 1000-1200℃, and heat and pressure holding time is 3-4h.

[0009] (5) Forging: In order to further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloy after solidification, forging is adopted; the forging process is as follows: heat treatment at 1150-1250℃ for 1~3h, initial forging temperature is 1120~1200℃ (preferably 1180-1200℃), final forging temperature is 900~1050℃ (preferably 1020-1050℃), and forging ratio is ≥4; (6) Heat treatment: The alloy after forging is heat treated. The process is as follows: hold at 1100-1250℃ (preferably 1150-1200℃) for 60-90 minutes (preferably 60-70 minutes) and then air-cool or water-cool. Remove the cladding before heat treatment.

[0010] The design concept of this invention is: 1. This invention uses Ni as the alloy matrix and adds a high Mo content. Mo is a strong solid solution strengthening element in nickel-based alloys, which can increase the resistance to dislocation movement, improve the high temperature strength of the alloy, give the alloy a stable austenitic structure at high temperature, have good high temperature structural stability, and also give the alloy excellent resistance to molten salt corrosion in molten fluoride salts.

[0011] 2. This invention forms a Mo-rich carbide precipitate phase with a certain density and a size of 2-5 μm by adding C and Mo. The Mo-rich carbide is more abundant than the Cr-rich carbide. 23 The C6 phase is more stable and will reduce Cr 23 The tendency of C6 phase to form at grain boundaries can, to some extent, inhibit intergranular corrosion, while the more stable Mo-rich carbides improve the material's resistance to high-temperature creep.

[0012] 3. This invention adds Nb to nickel-based alloys. Nb is a strong carbide-forming element that absorbs additional C besides Mo-rich carbides, further reducing Cr content. 23 The tendency to form the C6 phase improves the material's resistance to intergranular corrosion and its high-temperature mechanical properties.

[0013] 4. This invention uses a nickel-based alloy as the substrate and employs ball milling and hot isostatic pressing processes to uniformly disperse nano-sized Y2O3 powder in the nickel-based alloy matrix. The interface between Y2O3 and the nickel-based alloy absorbs helium generated in the neutron-irradiated material, inhibiting the embrittlement of the material and improving its resistance to neutron irradiation. At the same time, it uses Y2O3 to pin the grain boundaries, increasing grain boundary stability and improving its durability under high temperature and long-term service conditions.

[0014] 5. This invention refines the size of nano-oxides by adding Ti to nickel-based alloys. Ti reacts with Y₂O₃ to form a finer Y₂Ti₂O₇ phase. The Y₂Ti₂O₇ phase has a semi-coherent relationship with the matrix interface, enabling it to better absorb radiation defects. Simultaneously, the finer oxides result in a higher number density, further improving the material's radiation resistance by dispersing radiation defects.

[0015] 6. This invention employs an innovative ball milling process to obtain a special microstructure: a microstructure in which fine outer grains enclose coarse inner grains, which enables the alloy to achieve an excellent balance of strength and plasticity.

[0016] The main element contents of this invention are described below: Mo: 16.5~18.0wt.% Mo is an important element in improving the corrosion resistance of alloys in molten salts. Furthermore, Mo atoms account for approximately 12% more than Ni atoms, significantly increasing the lattice constant of Ni solid solution and the elastic stress field. This increases the resistance to dislocation movement and reduces stacking fault energy, resulting in a significant increase in yield strength. Simultaneously, Mo and C can form a large number of M6C-type carbides, which to some extent improve the high-temperature strength of the alloy.

[0017] Cr: 6.5~7.5wt.% Cr can dissolve in the γ matrix of the alloy, causing lattice distortion and resulting in elastic stress field strengthening, while simultaneously reducing stacking fault energy and improving the high-temperature strength of the alloy. Cr can also form a protective oxide film, improving the alloy's oxidation and corrosion resistance. However, Cr is selectively dissolved in molten salts, therefore its addition amount in the alloy must be strictly controlled.

[0018] Fe: 3.8~4.5wt.% Fe and Ni both belong to Group VIIIA, and Fe's lattice constant differs from Ni's by 3%. When added to a Ni matrix, Fe creates a long-range stress field due to lattice distortion, hindering dislocation movement and contributing to improved high-temperature strength. Simultaneously, the addition of Fe improves the alloy's plasticity and machinability, reducing alloy costs.

[0019] C: 0.01~0.045wt.% In high-temperature alloys, carbon (C) improves the alloy's mechanical properties by forming carbides. These carbides form granular, discontinuous carbides at grain boundaries, hindering grain boundary sliding and crack propagation, thus improving the alloy's creep rupture life and high-temperature strength. However, excessive C content can lead to excessive carbide precipitation, causing grain boundary embrittlement and facilitating crack nucleation and propagation. Therefore, the C content in the alloy must be strictly controlled. Mn: 0.4~1.0wt.% The addition of manganese (Mn) to a Ni matrix can increase the adhesion between the oxide film and the matrix, improve the oxide film's resistance to peeling, and enhance its antioxidant properties. Simultaneously, as a deoxidizer, Mn can improve the smelting process, reduce the content of impurities such as oxygen (O) and sulfur (S), and increase the purity of the alloy. However, Mn tends to agglomerate near grain boundaries, reducing grain boundary bonding strength; therefore, its addition amount must be strictly controlled.

[0020] Si: 0.35~0.5wt.% Si oxides exhibit extremely high thermal stability. In oxygen-containing environments, Si can combine with oxygen (O) to form dense oxides. Adding Si to alloys allows for the formation of a stable oxide film at high temperatures, which can hinder further corrosion from the external environment and improve corrosion resistance. Utilizing this property of Si, adding an appropriate amount of Si to steel provides excellent corrosion resistance.

[0021] Nb: 0.3~0.5wt.% Nitrogen (Nb) is a strong carbide-forming element that can fix some carbon and reduce the tendency of harmful elements to segregate at grain boundaries. Therefore, it can regulate the type and distribution of grain boundary precipitates. Adding Nb can reduce grain boundary embrittlement caused by Te and improve resistance to grain boundary cracking.

[0022] Ti: 0~0.3wt.% Ti is also a strong carbide-forming element, and its strong interaction with C can regulate the morphology and distribution of carbides, helping to reduce grain boundary weakening and cracking after irradiation. Adjusting the Ti content can improve the microstructure stability of the alloy at high temperatures.

[0023] This invention utilizes nano-sized Y2O3 to pin grain boundaries, ensuring grain boundary stability, and utilizes the interface between Y2O3 and the matrix to improve its resistance to neutron radiation.

[0024] The advantages and beneficial effects of this invention are: 1. The alloy of this invention possesses excellent high-temperature resistance, radiation resistance, and molten salt corrosion resistance. Using a nickel-based alloy as the base material, the addition of a large amount of Mo not only provides excellent resistance to molten salt corrosion but also significantly improves solid solution strengthening. The introduction of Nb improves grain boundary embrittlement after irradiation. The introduction of nano-sized Y₂O₃ dispersion strengthening greatly enhances its high-temperature mechanical properties. The introduction of Ti reacts with Y₂O₃ to form a finer Y₂Ti₂O₇ phase, further improving the material's radiation resistance.

[0025] 2. This invention utilizes ball milling and hot isostatic pressing processes to uniformly disperse nano-sized Y2O3 in a nickel-based alloy matrix. The interface between the introduced dispersed reinforcing phase and the nickel-based alloy absorbs helium generated in the neutron-irradiated material, thereby inhibiting the embrittlement of the material and improving its resistance to neutron irradiation.

[0026] 3. This invention achieves excellent high-temperature mechanical properties by uniformly dispersing nano-sized Y2O3 in a nickel-based alloy matrix and using dispersion strengthening to improve the stability of the high-temperature structure. Through the coordinated design of composition and preparation process, a special microstructure is achieved by having a fine outer layer encapsulating a coarse inner layer, which enables the alloy to obtain an excellent balance of strength and plasticity.

[0027] 4. The alloy obtained by this invention has a room temperature yield strength ≥970MPa, a tensile strength ≥1150MPa, and an elongation ≥13%; a 700℃ tensile strength ≥220MPa and an elongation ≥10%.

[0028] 5. The alloy obtained by this invention can be used as a structural material in thorium-based molten salt reactors that is resistant to high temperatures, radiation, and molten salt corrosion. Attached Figure Description

[0029] Figure 1 Metallographic image of Example 1 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0030] Figure 2 The image shown is the EBSD diagram of Example 1 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0031] Figure 3 This is a SEM image of Example 1 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0032] Figure 4 This is a TEM image of Example 1 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0033] Figure 5 Metallographic image of Example 2 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0034] Figure 6 Metallographic image of Example 3 of the oxide dispersion strengthened nickel-based alloy prepared according to the present invention.

[0035] Figure 7 Metallographic image of the powder metallurgy nickel-based alloy prepared for Comparative Example 1. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0037] Example 1 In this embodiment, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization powder spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0038] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ by mass was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5mm:Φ8mm:Φ10mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0039] (3) Powder filling and air extraction To remove adsorbed gases from the powder particles and improve density, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is a hollow, sealed cylinder with a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 98% of the sleeve's volume. The evacuation process is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld the sealing sleeve.

[0040] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0041] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding at 1250℃ for 2 hours, initial forging temperature of 1200℃, final forging temperature of 1050℃, and a forging ratio of 4.

[0042] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0043] Example 2 In this embodiment, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization powder spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0044] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 120 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0045] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, with the powder occupying 97% of the sleeve's volume. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0046] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0047] (5) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0048] The difference between this embodiment and Embodiment 1 is that the ball milling speed is reduced from 150 r / min to 120 r / min.

[0049] Example 3 In this embodiment, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization powder spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0050] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.3% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0051] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and improve density, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 99% of the sleeve's capacity. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0052] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1180℃, and the holding time is 4 hours.

[0053] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0054] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0055] The difference between this embodiment and Example 1 is that the amount of Y2O3 added is reduced from 0.5 wt.% to 0.3 wt.%.

[0056] Example 4 In this embodiment, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization powder spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0057] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.7% Y₂O₃ by mass was added to the atomized powder of the master alloy and ball-milled. The particle size of the Y₂O₃ powder was 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0058] (3) Powder filling and air extraction To remove adsorbed gases from the powder particles and improve density, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 97% of the sleeve's capacity. The evacuation process is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0059] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0060] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0061] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0062] The difference between this embodiment and Example 1 is that the amount of Y2O3 added is increased from 0.5 wt.% to 0.7 wt.%.

[0063] Example 5 In this embodiment, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization powder spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0064] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 40 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size <300 μm, and after sieving, powder with a particle size <100 μm was obtained.

[0065] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and improve density, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 99% of the sleeve's capacity. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0066] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0067] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0068] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0069] The difference between this embodiment and Embodiment 1 is that the ball milling time is reduced from 70 hours to 40 hours.

[0070] Comparative Example 1 In this comparative example, a method for preparing a nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was subjected to gas atomization powder spraying. The requirements for the nickel-based alloy were as follows: powder particle size < 75 μm, atomization gas pressure 4.0 MPa, superheat 200 °C, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0071] (2) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is <75μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, with the powder occupying 98% of the sleeve's volume. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0072] (3) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0073] (4) The heat treatment process of oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1150℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0074] The difference between this comparative example and Example 1 is that it does not involve the process of introducing dispersed oxides into the alloy matrix without mechanical alloying.

[0075] Comparative Example 2 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P: <0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was subjected to gas atomization spraying. The requirements for the nickel-based alloy were as follows: powder particle size <75μm, atomization gas pressure 4.0MPa, superheat 200℃, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0076] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the milling time was 10 h; and the rotation speed was 150 r / min. The particle size of the powder obtained after ball milling was <100 μm.

[0077] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is <100μm when placed in a protective sleeve. The sleeve is made of 304 stainless steel, is cylindrical and hollow, and has a wall thickness of 3mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 100% of the sleeve's capacity. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0078] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0079] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0080] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0081] The difference between this comparative example and Example 1 is that the ball milling time was reduced from 70 hours to 10 hours.

[0082] Comparative Example 3 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was subjected to gas atomization powder spraying. The requirements for the nickel-based alloy were as follows: powder particle size < 75 μm, atomization gas pressure 4.0 MPa, superheat 200 °C, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0083] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the milling time was 70 h; and the rotation speed was 90 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0084] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is 10-100 μm, and the casing is made of 304 stainless steel, with a cylindrical hollow shape and a wall thickness of 3 mm. After the powder is loaded into the casing, air is evacuated, and the powder occupies 99% of the casing's volume. The evacuation process for the casing is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0085] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0086] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0087] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0088] The difference between this comparative example and Example 1 is that the ball milling speed was reduced from 150 r / min to 90 r / min.

[0089] Comparative Example 4 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) Preparation of master alloy powder The master alloy was prepared using a vacuum induction melting furnace. By weight percentage, the master alloy composition was: Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was then subjected to gas atomization spraying with the following requirements for the nickel-based alloy: powder particle size < 75 μm, atomizing gas pressure 4.0 MPa, superheat 200 °C, and a protective atmosphere of argon with a volume purity of ≥ 99.99%.

[0090] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the milling time was 70 h; and the rotation speed was 210 r / min. The powder obtained after ball milling had a particle size of 10–500 μm, and after sieving, powder with a particle size of 10–250 μm was obtained.

[0091] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is 10-250 μm, and the casing is made of 304 stainless steel, with a cylindrical hollow shape and a wall thickness of 3 mm. After the powder is loaded into the casing, air is evacuated, and the powder occupies 99% of the casing's volume. The evacuation process for the casing is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0092] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0093] (5) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1150℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0094] The difference between this comparative example and Example 1 is that the ball milling speed was increased from 150 r / min to 210 r / min.

[0095] Comparative Example 5 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.41%, Cr: 6.97%, Fe: 4.19%, C: 0.041%, Mn: 0.75%, Si: 0.46%, S: 0.0005%, P: <0.0005%, N: 0.0011%, O: 0.014%, with Ni as the balance. The master alloy was subjected to gas atomization spraying. The requirements for the nickel-based alloy were as follows: powder particle size <75μm, atomization gas pressure 4.0MPa, superheat 200℃, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0096] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0097] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is 10-100 μm, and the casing is made of 304 stainless steel, with a cylindrical hollow shape and a wall thickness of 3 mm. After the powder is loaded into the casing, air is evacuated, and the powder occupies 97% of the casing volume. The evacuation process for the casing is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0098] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0099] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0100] (6) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1180℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0101] The difference between this comparative example and Example 1 is that it does not contain the elements Nb and Ti.

[0102] Comparative Example 6 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was subjected to gas atomization powder spraying. The requirements for the nickel-based alloy were as follows: powder particle size < 75 μm, atomization gas pressure 4.0 MPa, superheat 200 °C, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0103] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0104] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is 10-100 μm, and the casing is made of 304 stainless steel, with a cylindrical hollow shape and a wall thickness of 3 mm. After the powder is loaded into the casing, air is evacuated, and the powder occupies 99% of the casing's volume. The evacuation process for the casing is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0105] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0106] (5) Forging To further improve the density and mechanical properties of oxide dispersion strengthened nickel-based alloys after curing, forging was employed. The forging process was as follows: holding temperature at 1250℃, initial forging temperature at 1200℃, final forging temperature at 1050℃, and forging ratio of 4.

[0107] The difference between this comparative example and Example 1 is that there is no solution treatment process and the casing is removed before performance testing.

[0108] Comparative Example 7 In this comparative example, a method for preparing an oxide dispersion-strengthened nickel-based alloy is as follows: (1) The alloy was prepared using a vacuum induction melting furnace. By weight percentage, the alloy composition was Mo: 17.3%, Cr: 6.99%, Fe: 4.26%, C: 0.043%, Mn: 0.78%, Nb: 0.47%, Ti: 0.21%, Si: 0.44%, S: 0.0006%, P < 0.0005%, N: 0.0015%, O: 0.013%, with Ni as the balance. The master alloy was subjected to gas atomization powder spraying. The requirements for the nickel-based alloy were as follows: powder particle size < 75 μm, atomization gas pressure 4.0 MPa, superheat 200 °C, and protective atmosphere of argon with a volume purity of 99.99% or higher.

[0109] (2) Ball mill To achieve a dispersed distribution of nano-oxides in the material, 0.5% Y₂O₃ (by mass) was added to the atomized powder of the master alloy and ball-milled. The Y₂O₃ powder had a particle size of 30–50 nm. The ball-milling process parameters were controlled as follows: the ball-milling atmosphere was argon gas with a volume purity of ≥99.99%; the grinding balls were 304 stainless steel balls; the total mass of the grinding balls was 40 kg; the mass ratio of grinding balls was Φ5 mm:Φ8 mm:Φ10 mm = 5:3:2; the ball-to-material mass ratio was 10:1; the ball-milling time was 70 h; and the rotation speed was 150 r / min. The powder obtained after ball milling had a particle size of 10–300 μm, and after sieving, powder with a particle size of 10–100 μm was obtained.

[0110] (3) Powder filling and air extraction To remove adsorbed gas from the powder particle surface and reduce porosity, the ball-milled powder particle size is 10-100 μm, and the sleeve is made of 304 stainless steel, with a cylindrical hollow shape and a wall thickness of 3 mm. After the powder is loaded into the sleeve, air is evacuated, and the powder occupies 100% of the sleeve's capacity. The evacuation process for the sleeve is as follows: the vacuum pressure is 10... -2 Pa, temperature 450℃, time 8h, after evacuation, weld and seal.

[0111] (4) Hot isostatic pressing The hot isostatic pressing (HIP) curing process for the sheath is as follows: pressure is 170 MPa, temperature is 1150℃, and the holding time is 4 hours.

[0112] (5) The heat treatment process of the oxide dispersion strengthened nickel-based alloy is as follows: the solution treatment process parameters are 1150℃ for 60 min and then air-cooled to room temperature. The cladding is removed before heat treatment.

[0113] The difference between this comparative example and Example 1 is that no forging process was used.

[0114] Table 1 Mechanical properties of each embodiment and comparative example at room temperature

[0115] Note: The room temperature tensile properties test was conducted in accordance with GB / T 228.1.

[0116] The results of Example 1 show that the alloy microstructure is a fine-grained continuous matrix, with coarse grains discontinuously distributed within the fine grains. Figure 1 , 2 The fine-grained region has a grain size of approximately 50-500 nm, an average grain size of approximately 202 nm, and an area of ​​approximately 44.6%; the coarse-grained region has a grain size of approximately 5-50 μm, an average grain size of approximately 15 μm. Figure 3 Y₂O₃ is uniformly dispersed in the fine grains, with a number density of 1.5 × 10⁻⁶. 22 Size 10-50nm, average size approximately 20nm ( Figure 4 The coarse grains contain virtually no Y₂O₃. It exhibits excellent mechanical properties, with a yield strength and tensile strength of 1064 MPa and 1254 MPa at room temperature, respectively, and an elongation of 20.0%; at 700℃, the tensile strength is 510 MPa, and the elongation is 13.5%.

[0117] Compared to Example 1, in Example 2, the ball milling speed was reduced from 150 r / min to 120 r / min. This reduction in speed helps to mitigate the cold welding phenomenon of the powder, and the size of the ball-milled powder is similar to that of the atomized powder. Due to the reduced ball milling energy, the powder transitions from primarily crushing to primarily deforming, resulting in a decrease in the alloying degree between the oxide and the powder. Figure 5 As shown, the fine-grained region has a lower integral number, with a fine-grained area of ​​approximately 32.8% and an average grain size of 214 nm, while the coarse-grained region has an average grain size of 17 μm. The oxide number density is 1.2 × 10⁻⁶. 22 The average size is 27 nm. As shown in Table 1, its strength and plasticity are reduced to varying degrees. The yield strength and tensile strength decreased from 1064 MPa and 1254 MPa to 993 MPa and 1208 MPa, respectively, and the elongation decreased from 20.0% to 16.5%. The tensile strength at 700℃ decreased from 510 MPa to 489 MPa, and the elongation decreased to 12.5%.

[0118] In Example 3, compared to Example 1, the amount of Y₂O₃ added was reduced from 0.5 wt.% to 0.3 wt.%. Due to the reduced amount of nano-oxide added, the number density of dispersed oxides in the alloy matrix decreased to approximately 1.0 × 10⁻⁶. 22The average grain size is 24 nm. The area of ​​fine grains is approximately 37.2%, with an average grain size of 220 nm in the fine-grained region and an average grain size of 35 μm in the coarse-grained region. Compared to Example 1, the size difference between coarse and fine grains is greater, leading to a greater difference in mechanical properties between the coarse and fine grain structures; the oxide number density is lower, resulting in a weaker pinning effect. Compared to Example 1, its room temperature mechanical properties show a decrease in yield strength and tensile strength from 1064 MPa and 1254 MPa to 1006 MPa and 1203 MPa, respectively, and an elongation from 20.0% to 17.0%. At 700°C, the tensile strength decreases to 475 MPa, and the elongation decreases to 11.5%.

[0119] In Example 4, compared to Example 1, the amount of Y₂O₃ added was increased from 0.5 wt.% to 0.7 wt.%. Due to the increased amount of nano-oxide added, the number of dispersed oxides in the alloy matrix increased to approximately 2.4 × 10⁻⁶. 22 The average grain size is 24 nm. The proportion of fine grains is approximately 49.5%, with an average grain size of 217 nm in the fine-grained region and an average grain size of 20 μm in the coarse-grained region. Oxide agglomeration and coarsening occur in the coarse grains, with the oxide size reaching up to 160 nm after coarsening. The higher number density of oxide pinning the grain boundaries increases its strength, while the coarse oxides become crack initiation sources during subsequent tensile testing, reducing the material's plasticity. In terms of strength, the yield strength and tensile strength increased from 1064 MPa and 1254 MPa to 1183 MPa and 1368 MPa, respectively. The elongation decreased to some extent compared to Example 1, from 20.0% to 13.0%. The tensile strength at 700°C increased to some extent, from 510 MPa to 533 MPa, while the elongation remained at 13.5%.

[0120] Compared to Example 1, the ball milling time in Example 5 was reduced from 70 h to 40 h. With the shortened ball milling time, the oxides were dispersed more evenly on the surface of the powder, resulting in a lower proportion of fine grains after sintering (35.1%). Compared to the alloy obtained after sintering in Example 1, the fine grain size was similar, with an average grain size of 223 nm in the fine grain region. The coarse grains filled the core region, with a similar average size of 15 μm, but the oxide dispersion was lower, approximately 1.2 × 10⁻⁶. 22 The average size of the oxide is 27 nm. Its strength is lower than that of Example 1; the yield strength and tensile strength are lower than 977 MPa and 1159 MPa, respectively; the plasticity is slightly lower (17.0%); the tensile strength at 700°C is lower than 510 MPa to 482 MPa; and the elongation is lower than 13.0%. Comparative Example 1, compared to Example 1, involves dispersion strengthening of the nickel-based alloy matrix without the addition of Y2O3 powder. Figure 7As shown in the microstructure of the powder metallurgy nickel-based alloy prepared in Comparative Example 1, the grains in the material are equiaxed, exhibiting a uniform equiaxed grain structure with an average grain size of 15 μm. At this temperature, the yield strength is 558 MPa, the tensile strength is 982 MPa, and the elongation is 41.5%. The tensile strength at 700℃ is 411 MPa, and the elongation is 20.0%.

[0121] Compared to Example 1, the ball milling time in Comparative Example 2 was reduced from 70 h to 10 h. This reduction in ball milling time decreased the degree of powder alloying, resulting in an oxide number density of 5.5 × 10⁻⁶ in the sintered alloy. 21 The average grain size is 35 nm. The proportion of fine grains is low, covering approximately 13.4% of the area. The average grain size in the fine-grained region is 203 nm, while the average grain size in the coarse-grained region is 32 μm. Due to the increased oxide size, some regions exhibit a decrease in elongation compared to Comparative Example 1, at 30.0%. The strength at room temperature is significantly lower than in Example 1, with yield strength and tensile strength decreasing from 1064 MPa and 1254 MPa to 667 MPa and 1052 MPa, respectively. The tensile strength at 700 °C decreases to 427 MPa, and the elongation is 16.5%.

[0122] Compared to Example 1, the ball milling speed in Comparative Example 3 was reduced from 150 r / min to 90 r / min. The reduced milling speed shifted the powder's composition from primarily crushing to primarily deforming, decreasing the alloying degree between the oxide and the powder. Similar to Comparative Example 2, alloying mainly occurred on the powder's surface. After sintering, only a small amount of fine grains remained, with a surface area of ​​approximately 8.6%. The average grain size in the fine grain region was 200 nm, while the average grain size in the coarse grain region was 48 μm. The insufficient ball milling time resulted in uneven alloying between the oxide and the alloy powder. After sintering, Y₂O₃ was mainly dispersed within the fine grains, with a number density of 3.7 × 10⁻⁶. 21 The average size is 40 nm, and Y2O3 particles are aggregated at the grain boundaries. Its yield strength and tensile strength are 652 MPa and 1033 MPa, respectively, with an elongation of 32.0%. At 700℃, the tensile strength is 425 MPa, and the elongation is 15.5%.

[0123] Compared to Example 1, the ball milling speed in Comparative Example 4 was increased from 150 r / min to 210 r / min. This further increase in speed intensified the cold welding of the powder; the rate of cold welding during ball milling was much greater than the rate of breakage, resulting in larger powder sizes. Because deformation did not easily reach the core of the alloy powder, the alloying degree between the large powder core and the oxide was low, with only the outer layer achieving sufficient alloying. The oxide number density was 8.7 × 10⁻⁶. 21 The average size is 30nm. For example... Figure 6As shown, the sintered alloy microstructure still consists of a fine-grained matrix with discontinuous coarse grains. However, the area fraction of the fine grains is 27.4%, the average grain size in the fine-grained region is 120 nm, and the average grain size in the coarse-grained region is 47 μm. Due to the increased difference in size and volume fraction between the fine and coarse grains, the deformation compatibility is affected to some extent. Consequently, the strength and plasticity of the material decrease to a certain degree. The yield strength and tensile strength decrease from 1064 MPa and 1254 MPa to 871 MPa and 1135 MPa, respectively, and the elongation decreases from 20.0% to 18.5%. The tensile strength at 700℃ decreases significantly, from 510 MPa to 457 MPa, and the elongation decreases from 13.5% to 11.0%.

[0124] Comparative Example 5, compared to Example 1, does not contain Nb and Ti. Since Nb is a strong carbide-forming element, it can improve the stability of carbides, and the addition of Ti can result in a finer size of the dispersion-strengthening phase. The area of ​​the fine-grained region is approximately 43.5%, the average grain size of the coarse-grained region is 16 μm, and the average grain size of the fine-grained region is 197 nm. The number density of Y₂O₃ is 1.1 × 10⁻⁶. 22 The average size is 28 nm, which is larger than that of Example 1. As can be seen from Table 1, its strength and plasticity are slightly reduced. The yield strength and tensile strength decreased from 1064 MPa and 1254 MPa to 1053 MPa and 1216 MPa, respectively. The elongation did not change significantly. The tensile strength at 700℃ decreased from 510 MPa to 463 MPa, and the elongation decreased from 13.5% to 13.0%.

[0125] Comparative Example 6, compared to Example 1, does not undergo solution treatment. Through different heat treatment regimes, alloys with different grain sizes, precipitate sizes, distributions, and contents can be obtained. Compared to Example 1, which underwent solution treatment, Comparative Example 6 has smaller grain sizes, with an average grain size of 11 μm in the coarse-grained region and 180 nm in the fine-grained region. The size difference between coarse and fine grains is reduced, and the area of ​​fine grains is approximately 43.9%. The number density of Y₂O₃ is 1.7 × 10⁻⁶. 22 The average size is 24 nm. Its yield strength and tensile strength are 1087 MPa and 1277 MPa, respectively, and the elongation decreases from 20.0% to 13.0%. The tensile strength at 700℃ decreases from 510 MPa to 461 MPa, and the elongation decreases from 13.5% to 11.5%.

[0126] Comparative Example 7, compared to Example 1, does not involve a forging process. The forging process helps to further densify the alloy after hot isostatic pressing, resulting in a denser material, increased strength, growth of fine grains, reduced size difference between coarse and fine grains, and better deformation coordination. In Comparative Example 7, the area of ​​fine grains is approximately 50.8%, the average grain size of the coarse grain region is 26 μm, and the average grain size of the fine grain region is 127 nm. The number density of Y₂O₃ is 1.5 × 10⁻⁶. 22 The average size is 25 nm. Compared with Example 1, the yield and tensile strength of Comparative Example 7 at room temperature decreased, with the yield strength and tensile strength decreasing from 1064 MPa and 1254 MPa to 749 MPa and 1116 MPa, respectively. The elongation also decreased significantly, from 20.0% to 15.5%. The tensile strength at 700°C decreased from 510 MPa to 442 MPa, and the elongation decreased from 13.5% to 10.0%.

[0127] The above embodiments are only for illustrating the technical concept and features of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An oxide dispersion-strengthened nickel-based alloy, characterized in that: The mixture includes a master alloy and a dispersed oxide phase therein. The master alloy composition, by weight percentage, is as follows: Mo: 16.5–18.0%, Cr: 6.5–7.5%, Fe: 3.8–4.5%, C: 0.01–0.045%, Mn: 0.4–1.0%, Si: 0.35–0.5%, Nb: 0.3–0.5%, Ti: 0–0.3%, S: 0–0.002%, P: 0–0.005%, N: 0–0.03%, O: 0–0.2%, Ni balance; the dispersed oxide phase is Y₂O₃, added at 0.3–0.7% (preferably 0.4–0.6%) of the master alloy mass.

2. The oxide dispersion-strengthened nickel-based alloy of claim 1, wherein: The alloy exhibits a grain structure characterized by a continuous fine-grained matrix with discontinuous coarse-grained particles distributed within it. The coarse-grained volume accounts for 30-50% of the total volume; the grain size in the coarse-grained region is 5-50 μm; and the grain size in the fine-grained region is 50-500 nm. Y₂O₃ is uniformly dispersed within the fine grains, with a number density of 10⁻⁶. 21 ~10 23 / m 3 The size is 10-50nm.

3. The oxide dispersion strengthened nickel-based alloy according to claim 1 or 2, characterized in that: This microstructure results in an alloy with a room temperature yield strength ≥970MPa, tensile strength ≥1150MPa, and elongation ≥13%; and a 700℃ tensile strength ≥470MPa and elongation ≥10%.

4. A method for preparing an oxide dispersion-strengthened nickel-based alloy according to any one of claims 1-3, characterized in that: The preparation of this alloy includes the following steps: (1) Atomization of the master alloy powder; (2) Ball milling: Y2O3 powder is added to the atomized powder of the master alloy during the ball milling process, and the Y2O3 powder is fully dispersed in the nickel-based alloy powder to achieve alloying; (3) Encapsulation and evacuation; (4) Hot isostatic pressing and curing; (5) Forging; (6) Heat treatment.

5. The method of producing an oxide dispersion strengthened nickel-based alloy according to claim 4, characterized in that: In step (1), the method of first smelting the master alloy ingot and then spraying it with gas atomization powder can be adopted, or the master alloy powder that meets the composition of the master alloy can be obtained directly by gas atomization powder spraying. The gas atomization powder spraying parameters are: atomization gas pressure 3.5~4.2MPa (preferably 3.8-4.1MPa), superheat 200~300℃ (preferably 200-240℃), and the protective atmosphere is argon gas with a volume purity of 99.99% or higher, so as to ensure that the powder particle size is <75μm.

6. The method of producing an oxide dispersion strengthened nickel-based alloy according to claim 4, characterized in that: In step (2), Y2O3 powder with a particle size of 30-50 nm is selected and ball-milled with the master alloy atomized powder in the required amount. The process parameters are as follows: the ball milling atmosphere is argon gas with a volume purity of 99.99% or higher, the grinding balls are 304 stainless steel balls, the mass ratio of grinding balls is Φ5mm:Φ8mm:Φ10mm=4-6:2.5-3.5:1.5-2.5, the mass ratio of ball to material is 8-12:1, the ball milling time is 40-70h, the rotation speed is 120-150r / min, and the particle size range of the powder obtained after ball milling is 10-300μm. After sieving, powders with different particle size ranges are obtained.

7. The method of producing an oxide dispersion strengthened nickel-based alloy according to claim 4, characterized in that: In step (3), in order to remove the gas adsorbed on the surface of the powder particles and improve the density, the powder is placed in a sleeve, vacuumed, and then welded and sealed. The sleeve is made of low carbon steel or 304 stainless steel, and is hollow and sealed in a cylindrical or square shape with a wall thickness of 2.5-3 mm. The particle size of the powder placed in the sleeve is 10-300 μm (preferably 10-100 μm), and the powder occupies >95% of the sleeve capacity. The vacuuming parameters of the sleeve are: vacuum pressure ≤10 -2 Pa, temperature 300~500℃, time 6~8h, after evacuation of the casing, weld and seal.

8. The method of producing an oxide dispersion strengthened nickel-based alloy according to claim 4, characterized in that: In step (4), the hot isostatic pressing curing process of the cladding is as follows: pressure is 120-180 MPa, temperature is 1000-1200℃, and heat and pressure holding time is 3-4 h.

9. The method of producing an oxide dispersion strengthened nickel-based alloy according to claim 4, characterized in that: In step (5), in order to further improve the density and mechanical properties of the oxide dispersion strengthened nickel-based alloy after solidification and molding, forging processing is adopted; the forging process is: holding at 1150-1250℃ for 1~3h, the initial forging temperature is 1120~1200℃ (preferably 1180-1200℃), the final forging temperature is 900~1050℃ (preferably 1020-1050℃), and the forging ratio is ≥4; in step (6), the heat treatment process is: holding at 1100~1250℃ (preferably 1150-1200℃) for 60~90min (preferably 60-70min) and then air-cooled or water-cooled, and the cladding is removed before heat treatment.

10. Use of an oxide dispersion-strengthened nickel-based alloy according to any one of claims 1 to 3, characterized in that: This alloy can be used as a structural material in one or more of the following environments: high-temperature environment, irradiation environment, or molten salt corrosion environment in thorium-based molten salt reactors.

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