Application and preparation method of nano nitride dispersion strengthened nickel-based superalloy

Abstract

The invention relates to application and a preparation method of a nano nitride dispersion strengthened nickel-based superalloy, and belongs to the technical field of superalloy materials. The alloy comprises the following components in percentage by mass: 50.0 to 55.0 percent of Ni, 21.0 to 35.0 percent of Cr, 3.5 to 5.5 percent of Nb, 3.0 to 5.0 percent of Mo, 1.0 to 3.0 percent of Co, 0.3 to 1.1 percent of Al, 0.6 to 2.2 percent of Ti, 0.1 to 0.3 percent of Si, 0.01 to 1.0 percent of rare earth element (RE), 0.01 to 0.05 percent of C, 0.01 to 0.15 percent of N, 0.002 to 0.020 percent of B and the balance of Fe and impurities. By regulating and controlling the RE / N atomic ratio (1: 1-2: 3) and the Ti / Al ratio (1.5-2: 1) and combining selective laser melting (SLM) 3D printing and a multi-stage heat treatment process in a nitrogen-containing atmosphere, nanoscale rare earth nitride particles with the average size of 1-10 nm and the number density of 1 * 10 < 22 >-3 * 10 < 24 > m <-3 > are generated in an alloy matrix, and gradient distribution is formed at a gamma phase interface and a grain boundary (the surface density is 20-50% higher than that of the interior). The yield strength of the alloy at 750 DEG C reaches 1150-1260 MPa, the creep life is prolonged by 2-10 times compared with that of a traditional alloy, the use temperature upper limit is improved by 50-100 DEG C, and the alloy is suitable for high-temperature parts such as aero-engine turbine discs and combustion chambers and has high strength, long service life and oxidation resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloy materials, and in particular to an application and preparation method of a nano-nitride dispersion-strengthened nickel-based high-temperature alloy with excellent high-temperature resistance and oxidation resistance. Background Art

[0002] Superalloys are a class of materials designed to withstand long-term operation at temperatures exceeding 600°C and under certain stresses. They exhibit excellent high-temperature strength, good oxidation and corrosion resistance, as well as excellent fatigue performance and fracture toughness. Consequently, they are widely used in critical sectors such as aerospace, nuclear energy, and petroleum, crucial for national security and public safety. With the rapid development of the aerospace, petroleum, and advanced nuclear energy industries, the target operating temperatures of superalloys are continuously increasing. For example, nickel-based superalloys used as materials for aircraft turbine disks must withstand the most demanding conditions. Modern aircraft engines demand ever-increasing power and efficiency. Raising the inlet temperature of turbine disks is one of the key approaches to achieving high thrust and efficiency. This demands increasingly higher temperatures for turbine disks, placing even higher demands on their overall performance, especially their high-temperature performance. Currently, performance improvements in superalloy materials used in turbine disks for aerospace engines, such as GH4169, GH4133B, FGH97, and Inconel718, are reaching a bottleneck. There is an urgent need to develop new superalloys with higher operating temperatures and longer service lives at high temperatures.

[0003] In existing technologies, rare earth elements improve material properties by reducing the nitrogen and sulfur content in alloys and their irregular inclusions. This is primarily due to the high negative standard Gibbs free energy of rare earth element binding with nitrogen and sulfur. On the one hand, trace rare earth element additions can reduce the nitrogen and sulfur content in high-temperature alloy ingots to below 10 ppm, thereby preventing the formation of large nitrogen sulfide inclusions. On the other hand, rare earth elements dissolved in the alloy preferentially form rare earth nitrogen sulfides at high temperatures, improving the material's high-temperature oxidation resistance. The segregation of rare earth elements at grain and phase boundaries positively promotes microstructural stability. However, due to the rapid reaction of nitrogen and rare earth elements in molten alloys and their high negative standard Gibbs free energy of binding, existing technologies struggle to achieve high-solution coexistence of nitrogen and rare earth elements in the solidified alloy structure. Consequently, dispersion strengthening using nano-sized rare earth nitride particles has failed to improve the high-temperature properties of nickel-based superalloys and address the issues of low strength and short life. Summary of the Invention

[0004] The present invention aims to provide an application and preparation method for a nano-nitride dispersion-strengthened nickel-based superalloy. By optimizing the relative ratio of rare earth elements to nitrogen and designing a preparation process, the invention aims to address the three issues inherent in existing nickel-based superalloys: low operating temperature, low strength, and short lifespan.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: In a first aspect, a nano-nitride dispersion-strengthened nickel-based high-temperature alloy comprises the following components by mass percentage:

[0006] Ni: 50.0-55.0%,

[0007] Cr: 21.0-35.0%,

[0008] Nb: 3.5-5.5%,

[0009] Mo: 3.0-5.0%,

[0010] Co: 1.0-3.0%,

[0011] Al: 0.3-1.1%,

[0012] Ti: 0.6-2.2%,

[0013] Si: 0.1-0.3%,

[0014] Rare earth elements (RE): 0.01-1.0%,

[0015] C: 0.01-0.05%,

[0016] N: 0.01-0.15%,

[0017] B: 0.002-0.020%,

[0018] S≤0.003%,

[0019] P≤0.003%,

[0020] The balance is Fe and unavoidable impurities;

[0021] The solid structure of the alloy contains rare earth nano-nitride particles with an average size of 1-10 nm and a particle number density of 1×10 22 -3×10 24 m -3 , and the number density of the nitride particles in the γ phase matrix, γ' phase, γ" phase interface and grain boundary is higher than that in the matrix.

[0022] In this application, by optimizing the atomic ratio of rare earth elements (RE) and nitrogen (N) and innovatively designing the preparation process, a high-density dispersed distribution of nano-sized nitride particles in the γ phase matrix, γ' / γ" phase interface and grain boundaries is achieved. The average size of the nanoparticles is 1-10nm, and the number density is 1×10 22 -3×10 24 m -3, which significantly improves the alloy's high-temperature strength, creep resistance and oxidation resistance by pinning dislocation migration, inhibiting grain boundary slip and reducing the diffusion rate of atoms along fast diffusion channels. At the same time, combined with vacuum induction melting, laser selective melting (SLM) 3D printing under a nitrogen protective atmosphere and multi-stage heat treatment processes, it effectively regulates the gradient distribution of nitrogen and the solid-phase reaction of rare earth elements, while avoiding coarse inclusions and forming a nitride number density gradient from the surface to the interior (the surface is 20-50% higher than the interior), further optimizing the structural stability under high-temperature environments. The alloy has a yield strength of 1150-1260MPa at 750℃, a creep life 2-10 times higher than that of traditional nickel-based alloys, and an upper temperature limit increased by 50-100℃. Through the coordinated design of composition and process, it takes into account both cost and performance under the premise of controllable rare earth content. It is suitable for the manufacture of high-temperature key components such as turbine disks and combustion chambers of aircraft engines, and has significant engineering application value.

[0023] In a specific embodiment of the first aspect, the rare earth element (RE) is selected from at least one of lanthanum (La), yttrium (Y), cerium (Ce), gadolinium (Gd), erbium (Er), neodymium (Nd), praseodymium (Pr), terbium (Tb), samarium (Sm), dysprosium (Dy), and scandium (Sc), and the atomic ratio of RE to N is 1:1 to 2:3.

[0024] In a specific embodiment of the first aspect, the mass percentage ratio of Ti to Al is 1.5-2:1.

[0025] In a second aspect, a method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy is characterized by comprising the following steps:

[0026] Step 1: vacuum induction melting to prepare a primary alloy ingot, the composition of which is as described in claim 1, and processing to obtain an alloy bar with a central through hole;

[0027] Step 2: atomizing and pulverizing the rod material under a vacuum degree of ≤3×10-2Pa to obtain spherical master alloy powder with a particle size of 20-60 μm;

[0028] Step 3: Performing laser selective melting (SLM) 3D printing on the master alloy powder under a nitrogen-containing protective atmosphere, wherein:

[0029] The protective atmosphere is a mixture of nitrogen and argon, with nitrogen accounting for 0.1-1% by volume;

[0030] Powder preheating temperature is 300-1000℃;

[0031] Laser power 200-500W, spot diameter 20-120μm, scanning speed 1000-5000mm / s, layer thickness 20-100μm;

[0032] Step 4: Heat treatment of 3D printed components, including:

[0033] First homogenization: 1150℃ for 20-50 hours;

[0034] Second homogenization: 1185℃ for 10-50 hours;

[0035] Solution treatment: 950℃ for 1-5 hours;

[0036] Aging treatment: After keeping at 750-900℃ for 1-20 hours, cool to 650℃ at 50-100℃ / h and keep at this temperature for 1-5 hours, then air cool.

[0037] In a specific embodiment of the second aspect, the volume proportion of nitrogen in step three is 0.3-0.8%, the powder preheating temperature is 450-650° C., the laser power is 300-400 W, and the scanning speed is 2000-4000 mm / s.

[0038] In a specific embodiment of the second aspect, the aging treatment in step 4 is specifically: keeping warm at 850° C. for 10-15 hours and then slowly cooling to 650° C. and keeping warm for 3 hours.

[0039] In a specific implementation of the second aspect, in step three, the scanning pitch is 30-150 μm, and the ratio of the scanning pitch to the spot diameter is 0.5-1.5.

[0040] In a specific embodiment of the second aspect, after the atomization powdering in step 2, the method further includes screening under argon protection to remove powder with a particle size of >60 μm and <20 μm.

[0041] In a specific embodiment of the second aspect, the cooling method of the two homogenization treatments in step 4 is furnace cooling or inert gas forced cooling.

[0042] In a specific embodiment of the second aspect, the number density of the nitride particles in the 3D printed component is distributed in a gradient, wherein the number density in the surface area is 20-50% higher than that in the interior area.

[0043] The beneficial effects of the present invention are:

[0044] 1. The composition and preparation method of the nano-nitride dispersion-strengthened nickel-based superalloy provided by the present invention prioritize the relative ratio of rare earth elements to nitrogen content and update the preparation process, thereby solving the problems of low operating temperature, low strength, and short service life of nickel-based superalloys. Through composition design and special preparation technology, the main phase components of the final microstructure are γ phase matrix, ordered precipitation phases γ' and γ", carbides, and nano-nitride particles. The most distinctive feature is the high number density of rare earth nano-nitride particles in the structure, with an average particle size of 1-10nm and a number density of 1×10 22 -3×10 24 m -3 , and the number density is even higher at the γ, γ', γ" phase interfaces, grain boundaries, and dislocations. Nanoparticles pin dislocations, interface migration, and reduce the diffusion rate of atoms along fast diffusion channels such as grain boundaries and phase interfaces, thereby significantly improving the high-temperature strength, creep life, and oxidation resistance of high-temperature alloys.

[0045] 2. The composition and preparation method of the nano-nitride dispersion-strengthened nickel-based high-temperature alloy provided by the present invention can increase its upper limit operating temperature by 50-100°C compared to existing alloys without significantly increasing the rare metal content, and its creep life under the same temperature and stress is increased by 2-10 times. Without significantly increasing the cost, it has a significant effect on improving the service temperature and service life of the nickel-based high-temperature alloy, and thus has significant application economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a schematic flow chart of the method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy. DETAILED DESCRIPTION

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] like Figure 1 The preparation method of nano-nitride dispersion strengthened nickel-based high-temperature alloy is shown.

[0049] A nano-scale nitride dispersion-strengthened nickel-based high-temperature alloy comprises the following components in weight percentage: Ni: 50.0-55.0%, Cr: 21.0-35.0%, Nb: 3.5-5.5%, Mo: 3.0-5.0%, Co: 1.0-3.0%, Al: 0.3-1.1%, Ti: 0.6-2.2%, Si: 0.1-0.3%, RE: 0.01-1.0%, C: 0.01-0.05%, N: 0.01-0.15%, B: 0.002-0.020%, S≤0.003%, P≤0.003%, and the balance being Fe and unavoidable impurities.

[0050] (RE) element is one of lanthanum (La), yttrium (Y), cerium (Ce), gadolinium (Gd), erbium (Er), neodymium (Nd), praseodymium (Pr), terbium (Tb), samarium (Sm), dysprosium (Dy) or scandium (Sc), or multiple elements thereof, and the rare earth element content has a very important influence and effect on the alloy properties.

[0051] The final solid structure of the alloy includes a large number of rare earth nano-sized nitride particles with a particle number density of 1×10 22 -3×10 24 m -3 At the same time, the number density of nitride particles on the γ, γ', and γ" phase interfaces and grain boundaries is higher, pinning the phase interfaces and grain boundary migration and reducing the element diffusion rate, thereby improving the high temperature strength, creep life and oxidation resistance of the alloy.

[0052] A method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy, characterized by comprising the following steps:

[0053] Step 1: preparing a primary ingot by vacuum induction melting, wherein the components and their weight percentages are as follows: Ni: 50.0-55.0%, Cr: 21.0-35.0%, Nb: 3.5-5.5%, Mo: 3.0-5.0%, Co: 1.0-3.0%, Al: 0.3-1.1%, Ti: 0.6-2.2%, Si: 0.1-0.3%, RE: 0.01-1.0%, C: 0.01-0.05%, N: 0.01-0.15%, B: 0.002-0.020%, S≤0.003%, P≤0.003%, and the remainder is Fe and unavoidable impurities; removing defective parts at the head and tail of the primary ingot and performing a peeling treatment, and then processing to obtain alloy rods of different diameters, and opening a through hole in the center of the rod for atomization powder making.

[0054] Step 2: Place the rod with through hole obtained in step 1 under vacuum (3x10 -2Pa or less) to form spherical master alloy powder, which is then screened under argon protection to remove particles with a size greater than 60 μm and a size less than 20 μm to obtain a master alloy powder with high sphericity, low nitrogen content and good fluidity.

[0055] Step 3: Use SLS to 3D print the master alloy powder. 3D printing is carried out under a nitrogen-containing protective atmosphere. The protective atmosphere uses a mixture of nitrogen and argon, in which the volume ratio of nitrogen to the mixed gas is 0.1-1%. During the 3D printing process, the powder bed and the master alloy powder are heated to 300-1000℃. The 3D printing scanning speed is 1000-5000mm / s, the spot diameter used is 20-120μm, the scanning spacing is 30-150μm, the single layer powder thickness is 20-100μm, and the laser input power is 200-500W.

[0056] Step 4: Heat treat the 3D printed components, including two high-temperature homogenization cycles, solution treatment, and aging heat treatment. The first high-temperature homogenization cycle is at 1150°C for 20-50 hours, and the second high-temperature homogenization cycle is at 1185°C for 10-50 hours. The solution treatment cycle is at 950°C for 1-5 hours. The aging heat treatment cycle is at 750-900°C for 1-20 hours, followed by furnace cooling at 50-100°C / hour to 650°C, holding for 1-5 hours, and air cooling.

[0057] Example 1:

[0058] The preparation method of the nano-nitride dispersion-strengthened nickel-based high-temperature alloy improved in the embodiment of the present invention is a general typical composition and process.

[0059] A nano-scale nitride dispersion-strengthened nickel-based high-temperature alloy comprises the following components in weight percentage: Ni: 50.0-55.0%, Cr: 21.0-35.0%, Nb: 3.5-5.5%, Mo: 3.0-5.0%, Co: 1.0-3.0%, Al: 0.3-1.1%, Ti: 0.6-2.2%, Si: 0.1-0.3%, RE 0.01-1.0%, C: 0.01-0.05%, N: 0.01-0.15%, B: 0.002-0.020%, S≤0.003%, P≤0.003%, and the balance being Fe and unavoidable impurities.

[0060] Among them, the rare earth (RE) element is one of lanthanum (La), yttrium (Y), cerium (Ce), gadolinium (Gd), erbium (Er), neodymium (Nd), praseodymium (Pr), terbium (Tb), samarium (Sm), dysprosium (Dy) or scandium (Sc), or multiple elements thereof, and the content of rare earth elements has a very important influence and effect on the properties of the alloy.

[0061] The final solid structure of the alloy includes a large number of rare earth nano-nitride particles with an average particle size of 1-10 nm and a number density of 1×10 22 -3×10 24 m -3 At the same time, the number density of nitride particles is higher at the γ, γ', γ" phase interfaces, grain boundaries and dislocations. Pinning the phase interface and grain boundary migration and reducing the element diffusion rate, thereby significantly improving the high temperature strength, creep life and oxidation resistance of the high temperature alloy.

[0062] The reasons for the chemical composition and control range of the nano-scale dispersion-strengthened nickel-based high-temperature alloy of the present invention are explained as follows:

[0063] Ni (nickel): Ni is the primary element in nickel-based superalloys. It dissolves Cr, Fe, Mo, and Co in the crystal structure to form solid solutions, and forms strengthening phases with Al and Ti. Depending on the phase ratio requirements and the proportion of other dissolved elements in the final material, the Ni content is controlled to be 50.0%-55.0%.

[0064] Cr (chromium): Cr plays three roles in the composition of the present invention. First, as a nitrogen-carrying element, it absorbs nitrogen in the atmosphere during the 3D printing process and forms surface and grain boundary chromium nitride. During the subsequent heat treatment, the chromium nitride reacts with rare earth elements in the solid phase to precipitate rare earth-containing nano-nitrides in situ. Second, it promotes the formation of a single-phase austenite solid solution matrix. Third, it improves the material's resistance to oxidative corrosion. In order to prevent other alloying elements from nitriding during the 3D printing process and ensure that chromium nitride is reduced during the subsequent heat treatment, the Cr content is controlled at 21.0%-35.0%. Within this range, the higher the Cr content, the higher the atmospheric nitrogen content during the 3D printing process, and the higher the number density of nitrides in the final material.

[0065] Mo (Molybdenum): Mo is added primarily to dissolve into the single-phase austenite solid solution matrix, strengthening the matrix through solid solution and improving its corrosion resistance and high-temperature stability. The solid solution strengthening effect increases with increasing Mo content, but the effect is no longer significant above a certain level. Mo also has limited solubility in the matrix, so its content is controlled between 3.0% and 5.0%.

[0066] Co (Cobalt): Co forms the austenite matrix with Ni, Cr, Fe, and Mo. Co addition improves structural stability. Co, along with Al, Ti, and other materials, can form precipitates to strengthen grain boundaries, improving grain boundary stability. However, excessive Co content can lead to decreased toughness. Therefore, the Co content in this invention should be strictly controlled within a range of 1.0% to 3.0%.

[0067] Nb (Niobium): Nb is one of the main elements that form the γ-strengthening phase, significantly increasing the alloy's strength while also improving the material's high-temperature stability. The present invention incorporates a high Nb content primarily to produce a high content of the γ-strengthening phase. Simultaneously, through appropriate heat treatment, a small amount of NbC phase is generated. The Nb content in the present alloy is controlled within a range of 3.5% to 5.5%.

[0068] Al (aluminum), Ti (titanium), Si (silicon): The relative content of Al, Ti, and Si is one of the keys to the composition design of the present invention. Al is an essential element for the formation of γ' phase and γ" phase in nickel-based high-temperature alloys. The higher the Al content, the greater the precipitation amount of γ' and γ" phases. However, Al will combine with N to produce AlN phase that is difficult to eliminate, inhibiting the reaction between N and Cr and the introduction of solid-solution N, and making the material prone to cracking; Ti is easy to dissolve into the γ' phase, which can replace the Al atoms therein, slowing down the precipitation, and promoting the formation of rare earth-containing nano-nitrides; Si can promote the reaction of CrN formed in the 3D printing process with rare earth elements to form ternary nano-nitrides. In the present invention, the Ti content is higher than the Al content, and the Ti / Al content ratio is 1.5-2, so as to ensure that the final structure of the material contains a large amount of γ' phase, γ" phase and nano-nitrides at the same time; the Si content is lower than the Ti and Al contents, and higher than the rare earth element content.

[0069] Re (rare earth element): One of lanthanum (La), yttrium (Y), cerium (Ce), gadolinium (Gd), erbium (Er), neodymium (Nd), praseodymium (Pr), terbium (Tb), samarium (Sm), dysprosium (Dy), or scandium (Sc). This element is a key component in the design of the present invention. The rare earth element primarily reacts with nitrogen absorbed during the 3D printing process to form rare earth-containing nano-nitrides. The rare earth element content corresponds to the nitrogen content, with a Re / N atomic ratio of approximately 1:1-2:3, and an Re content of 0.01-1.0%.

[0070] Carbon (C): Carbon is an essential element for the formation of carbides in nickel-based superalloys. On the one hand, the precipitation of carbides at grain boundaries can refine grains, improving long-term strength and ductility. On the other hand, excessive carbides can lead to grain inhomogeneity and deteriorate alloy ductility. In the present material, carbides are a non-primary strengthening phase, and the C content is relatively low, at 0.01%-0.05%.

[0071] N (nitrogen): N is one of the most core elements in the nano-nitride dispersion-strengthened nickel-based high-temperature alloy of the present invention. Its main function is to form nano-nitrides with rare earth elements and Ti, Si, etc. to achieve nano-nitride dispersion strengthening. The higher the N content, the higher the volume fraction of nano-nitrides, but too high a N content will lead to the nitridation of other alloying elements and produce coarse nitride particles, which will reduce the performance of the material. According to the optimization of the nano-nitride content, the N content in the present invention is 0.01%-0.15%. At the same time, the way of introducing N is very important. It cannot be added during the initial smelting process, but needs to be introduced through atmosphere nitriding during the 3D printing process. The amount of introduction is controlled by the powder temperature and the nitrogen content in the atmosphere.

[0072] Boron (B): Boron segregation at grain and phase boundaries significantly improves the alloy's high-temperature durability and creep life, while also enhancing phase stability. However, excessive B deteriorates the alloy's hot workability and weldability. The B content in this invention is designed to be 0.002% to 0.020%, with the content increasing as the content of nano-nitrides increases.

[0073] S (sulfur) and P (phosphorus): In the composition design of the present invention, S and P are impurity elements, which will cause the coarsening and abnormal growth of nano-scale nitrides. In the design of the present invention, S≤0.003% and P≤0.003%.

[0074] See also Figure 1 A method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy comprises the following steps:

[0075] Step 1: Prepare a primary ingot by vacuum induction melting. Its composition, by weight, is as follows: Ni: 50.0-55.0%, Cr: 21.0-35.0%, Nb: 3.5-5.5%, Mo: 3.0-5.0%, Co: 1.0-3.0%, Al: 0.3-1.1%, Ti: 0.6-2.2%, Si: 0.1-0.3%, RE: 0.01-1.0%, C: 0.01-0.05%, N: 0.01-0.15%, B: 0.002-0.020%, S≤0.003%, P≤0.003%, with the remainder being Fe and unavoidable impurities. Defective areas at the head and tail of the primary ingot are removed and the surface is peeled. After this treatment, alloy bars of varying diameters are obtained. A through-hole is opened in the center of the bar for atomization and powdering.

[0076] Step 2: Place the rod with through hole obtained in step 1 under vacuum (3x10 -2 Pa or less) to form spherical master alloy powder, and sieve under argon protection to remove particles with a particle size greater than 60 μm and a particle size less than 20 μm to obtain a master alloy powder with high sphericity, low nitrogen content and good fluidity;

[0077] Step 3: Use SLS to 3D print the master alloy powder. 3D printing is carried out under a nitrogen-containing protective atmosphere. The protective atmosphere uses a mixture of nitrogen and argon, in which the volume ratio of nitrogen to the mixed gas is 0.1-1%. During the 3D printing process, the powder bed and the master alloy powder are heated to 300-1000℃. The 3D printing scanning speed is 1000-5000mm / s, the spot diameter used is 20-120μm, the scanning spacing is 30-150μm, the single layer powder thickness is 20-100μm, and the laser input power is 200-500W.

[0078] Step 4: Heat treat the 3D printed components, including two high-temperature homogenization treatments, solution treatment, and aging heat treatment. The first high-temperature homogenization treatment is at 1150°C for 20-50 hours, and the second high-temperature homogenization treatment is at 1185°C for 10-50 hours. The solution treatment is at 950°C for 1-5 hours. The aging heat treatment is at 750-900°C for 1-20 hours, then furnace cooled to 650°C at 50-100°C / hour, held for 1-5 hours, and air cooled.

[0079] The nickel-based alloy preparation method of the present invention employs the following process parameters: a 3D printing protective atmosphere with a nitrogen volume ratio of 0.3% in the mixed gas, the master alloy powder is heated to 450°C, the 3D printing scan speed is 2m / s, the spot diameter is 60μm, the scan interval is 45μm, the single layer powder thickness is 60μm, and the laser input power is 300W. After 3D printing, the component undergoes heat treatment with a first high-temperature homogenization at 1150°C for 25 hours and a second high-temperature homogenization at 1185°C for 15 hours; a solution treatment at 950°C for 3 hours; and an aging heat treatment at 850°C for 10 hours, followed by furnace cooling at 50-100°C / hour to 650°C, a holding time of 3 hours, and air cooling.

[0080] The functions of the process steps of the method for preparing nano-nitride dispersion-strengthened nickel-based high-temperature alloy of the present invention are as follows:

[0081] Step 1: Prepare a primary ingot by vacuum induction melting. This is to obtain a uniform alloy ingot containing the main alloy components for subsequent atomization and powdering. No nitrogen is added to the primary ingot.

[0082] Step 2: Atomization powder making, which is used to obtain master alloy powder with high sphericity, low nitrogen content and good fluidity for subsequent 3D printing.

[0083] Step three: 3D printing plays two roles in the method of the present invention. First, an appropriate amount of nitrogen is introduced into the alloy to react with Cr in the alloy powder to form surface and interface nitride layers. The nitrogen enters the solid phase organization for subsequent solid phase reaction to generate nano-scale nitrides. Second, the nickel-based high-temperature alloy of the invention is integrated and rapidly formed, and the desired components are directly formed through 3D printing, avoiding the aggregation and growth of nano-scale nitrides caused by the welding process during conventional component processing. Three key points need to be focused on in this step. The first is the nitrogen content in the 3D printing atmosphere, which accounts for 0.1-1% of the total volume of the protective gas to ensure that a certain amount of nitrogen enters the alloy composition. However, excessive nitrogen content will cause excessive nitridation of the powder. The second is the powder temperature, which needs to be heated to 300-1000°C to ensure a faster Cr-N reaction during the 3D printing process. At the same time, nitrogen can diffuse into the inner grain boundaries. Too high a speed will lead to excessive nitridation of the powder. The third is the control of 3D printing process parameters. A smaller spot diameter and faster scanning speed are conducive to forming a smaller molten pool volume and a better cooling rate, which is conducive to avoiding segregation and promoting the precipitation of nano-nitrides.

[0084] Step 4: Heat treatment. This method plays two main roles: first, it promotes the reaction of the surface and interface treated chromium nitride with rare earth elements to form nano-sized nitrides; second, it promotes the precipitation of precipitated phases such as γ', γ" phases and carbides. High-temperature homogenization primarily promotes element diffusion, improves alloy composition uniformity, and promotes the reaction of chromium nitride with rare earth elements; solution treatment primarily regulates composition uniformity and carbide precipitation; and aging heat treatment primarily promotes the precipitation of γ', γ" phases and nano-sized nitrides, forming a microstructure with high thermal stability.

[0085] The final solid structure of the alloy includes a large number of rare earth nano-nitride particles with an average particle size of 1-10 nm and a number density of 1×10 22 -3×10 24 m -3 At the same time, the number density of nitride particles is higher at the dislocation γ and γ', γ" phase interfaces and grain boundaries, pinning dislocations and grain boundary migration and reducing the element diffusion rate, hindering the growth of matrix grain size and improving the material's structural stability at high temperatures. As a result, the high-temperature strength, creep life and oxidation resistance of the alloy are significantly improved.

[0086] The mechanical properties of the nano-nitride dispersion strengthened nickel-based high-temperature alloy under the above composition and preparation process parameters are as follows:

[0087] Room temperature (25°C) tensile strength: yield strength 1380MPa, tensile strength 1450MPa, elongation 17%;

[0088] High temperature (750℃) tensile strength: yield strength 1210MPa, tensile strength 1320MPa, elongation 19%;

[0089] 750℃ / 925MPa creep life: 123 hours.

[0090] The nickel-based superalloy produced by the nano-nitride dispersion-strengthened nickel-based superalloy composition and preparation method of the present invention has a service temperature of 750°C or higher compared to existing alloys. The alloy's elemental composition ensures excellent corrosion resistance and long-term structural stability. At 25°C, the alloy has a yield strength of 900-1800 MPa and a deformation rate greater than 12%. At high temperatures of 650-1200°C, the yield strength reaches 1350-450 MPa and a deformation rate greater than 15%. The nickel-based superalloy of the present invention is highly suitable for manufacturing high-performance turbine disks, combustion chambers, and other components.

[0091] Example 2:

[0092] The embodiment of the present invention is a further optimization based on Example 1. The difference from Example 1 is that by increasing the Ti / Al content and increasing the RE and N contents, more rare earth nano-nitride phases are obtained, which has higher strength but reduced toughness.

[0093] The nickel-based alloy of the present invention contains the following components in percentage by mass: Ni: 51.0-51.5%, Cr: 25.0-26.0%, Nb: 4.5-4.8%, Mo: 3.2-3.5%, Co: 1.3-1.7%, Al: 0.6-0.8%, Ti: 1.0-1.2%, Si: 0.1-0.2%, RE: 0.08-0.10%, C: 0.01-0.02%, N: 0.06-0.08%, B: 0.002-0.004%, S≤0.003%, P≤0.003%, and the balance is Fe and unavoidable impurities.

[0094] The nickel-based alloy preparation method of the present invention employs the following process parameters: a 3D printing protective atmosphere with a nitrogen volume ratio of 0.5% in the mixed gas, the master alloy powder is heated to 550°C, the 3D printing scan speed is 3m / s, the spot diameter is 60μm, the scan interval is 45μm, the single layer powder thickness is 60μm, and the laser input power is 300W. After 3D printing, the component undergoes heat treatment with a first high-temperature homogenization at 1150°C for 25 hours and a second high-temperature homogenization at 1185°C for 15 hours; a solution treatment at 950°C for 3 hours; and an aging heat treatment at 850°C for 10 hours, followed by furnace cooling at 50-100°C / hour to 650°C, holding for 3 hours, and air cooling.

[0095] The mechanical properties of the nano-nitride dispersion strengthened nickel-based high-temperature alloy under the above composition and preparation process parameters are as follows:

[0096] Room temperature (25°C) tensile strength: yield strength 1430MPa, tensile strength 1497MPa, elongation 13%;

[0097] High temperature (750℃) tensile strength: yield strength 1268MPa, tensile strength 1332MPa, elongation 16%;

[0098] 750℃ / 925MPa creep life: 197 hours.

[0099] Example 3:

[0100] The embodiment of the present invention is basically the same as Examples 1 and 2, except that the Ti / Al content ratio is increased and the contents of RE, N, and B are increased, while the contents of alloy components such as Mo, Co, and Nb are reduced. The distribution and interface structure of nano-nitrides are controlled by adjusting process parameters, thereby reducing the cost of materials while maintaining high comprehensive performance, thereby achieving a compromise between performance and price.

[0101] The nickel-based alloy of the present invention comprises the following components in percentage by mass: Ni: 53.5-54.0%, Cr: 28.0-29.0%, Nb: 3.5-3.8%, Mo: 1.2-1.3%, Co: 1.0-1.1%, Al: 0.8-1.0%, Ti: 1.5-1.8%, Si: 0.18-0.20%, RE: 0.15-0.18%, C: 0.01-0.02%, N: 0.01-0.12%, B: 0.006-0.008%, S≤0.003%, P≤0.003%, and the balance is Fe and unavoidable impurities.

[0102] The nickel-based alloy preparation method of the present invention uses the following process parameters: in a 3D printing protective atmosphere, the volume ratio of nitrogen to the mixed gas is 0.8%, the master alloy powder is heated to 650°C, and the 3D printing scanning speed is 3m / s. The spot diameter is 60μm, the scanning interval is 45μm, the single layer powder thickness is 60μm, and the laser input power is 300W. After 3D printing, the component is heat treated for the first high-temperature homogenization at a temperature of 1150°C for 35 hours.

[0103] The second high-temperature homogenization temperature is 1185℃, and the time is 25 hours; the solution treatment temperature is 950℃, and the time is 5 hours; the aging heat treatment is at 850℃, kept warm for 15 hours, furnace cooled to 650℃ at 50-100℃ / hour, kept warm for 3 hours, and air cooled.

[0104] The mechanical properties of the nano-nitride dispersion strengthened nickel-based high-temperature alloy under the above composition and preparation process parameters are as follows:

[0105] Room temperature (25°C) tensile strength: yield strength 1330 MPa, tensile strength 1422 MPa, elongation 14%;

[0106] High temperature (750℃) tensile strength: yield strength 1157MPa, tensile strength 1210MPa, elongation 15%;

[0107] 750℃ / 925MPa creep life: 137 hours.

[0108] The superalloy components, proportions, and preparation methods described in the aforementioned embodiments of the present invention work in concert. First, nitrogen-free master alloy test bars are prepared in a vacuum induction melting furnace. Argon atomization is then used to atomize and pulverize the master alloy powder, followed by grading to produce a master alloy powder with high sphericity, low nitrogen content, and excellent fluidity. Selective laser sintering (SLS) is then used to control the temperature and atmosphere, introducing dissolved nitrogen and sintering the alloy powder. Finally, heat treatment is performed. The present invention focuses on the composition and proportion of the rare earth elements and the introduction of dissolved nitrogen during the selective laser sintering process. This allows for the in-situ solid-phase reaction precipitation of a large number of rare earth nano-nitrides, such as Y-Ti-N, Y-Si-N, and Y-Al-N, within the nickel-based superalloy matrix. These nano-nitrides pin dislocations and the migration of γ, γ', and γ" phase interfaces and grain boundaries, while reducing the nitrogen diffusion rate at high temperatures. This significantly improves the superalloy's high-temperature strength, creep life, and oxidation resistance.

[0109] The nano-nitride dispersion-strengthened nickel-based superalloy composition and preparation method provided in the aforementioned embodiments of the present invention focus on optimizing and updating the preparation process by utilizing the relative ratio of rare earth elements to nitrogen content, thereby addressing the issues of low operating temperature, low strength, and short service life of nickel-based superalloys. This nano-nitride dispersion-strengthened nickel-based superalloy can be used to manufacture complex and harshly designed aircraft engine and gas turbine components, nuclear reactor components, and other applications, while also improving their service temperature and service life.

[0110] It should be noted that in other embodiments of the present invention, within the scope of the steps, components, ratios, and process parameters recorded in the present invention, other different schemes obtained by making specific selections can all achieve the technical effects recorded in the present invention, so the present invention will no longer list them one by one.

Claims

1. Nano-nitride dispersion strengthened nickel-based high-temperature alloy, characterized in that: Calculated by mass percentage, it contains the following ingredients: Ni: 50.0-55.0%, Cr：21.0-35.0％、 Nb: 3.5-5.5%, Mo: 3.0-5.0%, Co: 1.0-3.0%, Al：0.3-1.1％、 Ti: 0.6-2.2%, Si: 0.1-0.3%, Rare earth elements (RE): 0.01-1.0%, C：0.01-0.05％、 N：0.01-0.15％、 B：0.002-0.020％、 S≤0.003％、 P≤0.003％， The balance is Fe and unavoidable impurities; The solid structure of the alloy contains rare earth nano-sized nitride particles with an average size of 1-10 nm and a particle number density of 1×10 22 -3×10 24 m -3 , and the number density of the nitride particles in the γ phase matrix, γ' phase, γ" phase interface and grain boundary is higher than that in the matrix.

2. The nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 1, characterized in that: The rare earth element (RE) is selected from at least one of lanthanum (La), yttrium (Y), cerium (Ce), gadolinium (Gd), erbium (Er), neodymium (Nd), praseodymium (Pr), terbium (Tb), samarium (Sm), dysprosium (Dy), and scandium (Sc), and the atomic ratio of RE to N is 1:1 to 2:

3.

3. The nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 1, characterized in that: The mass percentage ratio of Ti to Al is 1.5-2:

1.

4. A method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy, characterized in that: The following steps are involved: Step 1: vacuum induction melting to prepare a primary alloy ingot, the composition of which is as described in claim 1, and processing to obtain an alloy bar with a central through hole; Step 2: atomizing and pulverizing the rod material under a vacuum degree of ≤3×10-2Pa to obtain spherical master alloy powder with a particle size of 20-60 μm; Step 3: Performing laser selective melting (SLM) 3D printing on the master alloy powder under a nitrogen-containing protective atmosphere, wherein: The protective atmosphere is a mixture of nitrogen and argon, with nitrogen accounting for 0.1-1% by volume; Powder preheating temperature is 300-1000℃; Laser power 200-500W, spot diameter 20-120μm, scanning speed 1000-5000mm / s, layer thickness 20-100μm; Step 4: Heat treatment of 3D printed components, including: First homogenization: 1150℃ for 20-50 hours; Second homogenization: 1185℃ for 10-50 hours; Solution treatment: 950℃ for 1-5 hours; Aging treatment: After keeping at 750-900℃ for 1-20 hours, cool to 650℃ at 50-100℃ / h and keep at this temperature for 1-5 hours, then air cool.

5. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: In step 3, the volume proportion of nitrogen is 0.3-0.8%, the powder preheating temperature is 450-650° C., the laser power is 300-400 W, and the scanning speed is 2000-4000 mm / s.

6. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: The aging treatment in step 4 is specifically as follows: keeping the temperature at 850° C. for 10-15 hours and then slowly cooling to 650° C. and keeping the temperature at 650° C. for 3 hours.

7. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: In step 3, the scanning pitch is 30-150 μm, and the ratio of the scanning pitch to the spot diameter is 0.5-1.

5.

8. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: After the atomization powdering in step 2, the powder with a particle size greater than 60 μm and less than 20 μm is screened under argon protection to remove the powder.

9. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: The cooling method for the two homogenization treatments in step 4 is furnace cooling or forced cooling with inert gas.

10. The method for preparing a nano-nitride dispersion-strengthened nickel-based high-temperature alloy according to claim 4, characterized in that: The number density of nitride particles in the 3D printed component is distributed in a gradient, wherein the number density in the surface area is 20-50% higher than that in the interior area.

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