An oxidation-resistant nickel-based superalloy and a method of making the same

Abstract

The application discloses an antioxidant nickel-based high-temperature alloy and a preparation method thereof, and particularly relates to the technical field of high-temperature alloy materials, and the chemical composition of the antioxidant nickel-based high-temperature alloy comprises, in percentage by mass, 8.0-10.0% of chromium, 9.0-11.0% of cobalt, 9.5-10.5% of tungsten, 5.0-6.0% of aluminum, 1.0-2.0% of titanium, 2.5-3.5% of tantalum, 0.08-0.12% of carbon, 0.01-0.02% of boron, 0.1-0.3% of modified rare earth intermediate alloy, and the balance of nickel and inevitable impurities. The application effectively inhibits the interface reaction between the active element yttrium and the ceramic shell through a special intermediate alloy design and a late addition process, reduces oxide inclusions, improves the high-temperature antioxidant performance of the alloy, and improves the yield of precision casting.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy materials technology, and in particular to an antioxidant nickel-based high-temperature alloy and its preparation method. Background Technology

[0002] Nickel-based superalloys are core materials for turbine blades in aero-engines and gas turbines, components that need to operate for extended periods under extremely high temperatures and complex stress environments. To prevent corrosion from high-temperature gases, a dense, continuous alumina protective film must form on the alloy surface. Simple alumina films are prone to cracking and peeling during repeated heating and cooling; therefore, active elements such as yttrium, lanthanum, and hafnium need to be added to the alloy. These elements significantly enhance the adhesion between the oxide film and the alloy matrix, acting as a pinning agent to prevent the protective film from detaching, thereby extending the blade's service life.

[0003] However, the highly reactive chemical properties of these elements pose challenges to subsequent precision casting processes. In single-crystal or directional solidification casting, the molten alloy at high temperatures remains in contact with the ceramic mold shell for extended periods. Currently, commonly used ceramic mold shells are primarily composed of alumina or silicon dioxide, and the reactive elements in the melt, especially yttrium, readily react chemically with these ceramic materials.

[0004] This interfacial reaction leads to two direct consequences. Firstly, reaction products and the damaged mold shell surface peel off and fall into the molten alloy, forming non-metallic oxide inclusions. These inclusions disrupt the continuity of the alloy's internal structure, becoming crack initiations for low-cycle fatigue failure, directly resulting in a significant reduction in the yield of expensive single-crystal blades. Secondly, the reaction forms a difficult-to-remove sand layer on the casting surface. Simultaneously, a large amount of active elements are consumed in the reaction with the mold shell, resulting in insufficient effective content within the final casting, failing to provide the expected antioxidant effect.

[0005] To avoid the aforementioned issues, existing technologies typically limit the addition of yttrium to extremely low levels, such as below 50%. However, this presents another dilemma: excessively low content fails to provide sufficient adhesion for the oxide film, resulting in substandard antioxidant performance. While using ceramic shells with a full yttrium oxide coating can prevent the reaction, such shells are extremely expensive and difficult to popularize in large-scale production. Therefore, how to effectively introduce sufficient active elements to improve antioxidant performance while ensuring the stability of the casting process and the purity of the castings is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to effectively solve the technical problem of interfacial reaction between active elements and ceramic shell during precision casting, which leads to increased inclusions and decreased yield, while ensuring the excellent high-temperature oxidation resistance of nickel-based superalloys.

[0007] To achieve the above objectives, the present invention provides an antioxidant nickel-based superalloy, wherein the chemical composition of the antioxidant nickel-based superalloy comprises, by mass percentage: 8.0% to 10.0% chromium, 9.0% to 11.0% cobalt, 9.5% to 10.5% tungsten, 5.0% to 6.0% aluminum, 1.0% to 2.0% titanium, 2.5% to 3.5% tantalum, 0.08% to 0.12% carbon, 0.01% to 0.02% boron, 0.1% to 0.3% modified rare earth master alloy, and the balance being nickel and unavoidable impurities;

[0008] The modified rare earth master alloy is prepared by the following steps:

[0009] P1. Weigh out yttrium, magnesium, chromium and aluminum as raw materials according to the mass ratio;

[0010] P2. The raw material is placed in a water-cooled copper crucible in a vacuum arc melting furnace and repeatedly turned and melted under an argon protective atmosphere to obtain a master alloy ingot.

[0011] P3. Place the master alloy ingot in a quartz nozzle crucible and induction heat it to 1350℃-1400℃ under a vacuum of less than 0.005Pa to remelt it and obtain a homogeneous melt;

[0012] P4. The uniform melt is sprayed onto the surface of a high-speed rotating water-cooled copper roller with a linear velocity of 25-30 m / s using gas pressure for single-roller fast solidification, and then collected and crushed to obtain the modified rare earth intermediate alloy.

[0013] The antioxidant nickel-based superalloy is prepared by vacuum induction melting combined with precision casting. During the preparation process, the modified rare earth master alloy is added to the alloy melt 2-3 minutes before pouring, under an argon-filled environment with a pressure of 2000Pa-5000Pa.

[0014] In a preferred embodiment of the present invention, the raw materials for preparing the modified rare earth master alloy in step P1 include, by mass percentage:

[0015] Yttrium 35.0%-45.0%, magnesium 5.0%-8.0%, chromium 10.0%-15.0%, balance aluminum.

[0016] In another preferred embodiment of the present invention, the matrix grain size in the modified rare earth master alloy is less than 5 μm, and the yttrium-rich phase is dispersed in the aluminum matrix in the form of nano-precipitates of less than 500 nm.

[0017] In another preferred embodiment of the invention, the unavoidable impurities contain less than 0.001% sulfur, less than 0.002% phosphorus, less than 0.05% silicon, and in the final antioxidant nickel-based superalloy, the residual amount of magnesium is 0.005%-0.020%.

[0018] In another preferred embodiment of the present invention, in step P1, magnesium metal is wrapped in aluminum foil and placed at the bottom of a crucible, with yttrium and chromium metal covering it.

[0019] In another preferred embodiment of the present invention, in step P2, the melting process is repeated at least 4 times, and each melting process lasts for 2-5 minutes.

[0020] In another preferred embodiment of the present invention, in step P4, the gas medium for the injection pressure is high-purity argon, and the injection pressure is controlled at 0.02-0.05 MPa.

[0021] To achieve the above objectives, the present invention also provides a method for preparing the antioxidant nickel-based superalloy as described above, comprising the following steps:

[0022] S1. Except for aluminum, titanium, and modified rare earth master alloys, other metallic raw materials are loaded into the crucible of the vacuum induction melting furnace according to the specified proportions, and a vacuum is drawn until... Next, heat and melt;

[0023] S2. After all the furnace charge has melted, raise the temperature to 1550℃-1600℃ for refining and degassing;

[0024] S3. Cool to 1450℃, add aluminum and titanium, and perform electromagnetic stirring;

[0025] S4. Refill the furnace with argon gas to a pressure of 2000Pa-5000Pa, and add the modified rare earth master alloy 2-3 minutes before pouring;

[0026] S5. Adjust the melt temperature to 1420℃-1440℃ and pour it into a preheated ceramic mold.

[0027] In a preferred embodiment of the present invention, the refining and degassing time in step S2 is 15-30 minutes, and an appropriate amount of carbon is added during the refining process for deoxidation.

[0028] In another preferred embodiment of the present invention, the ceramic shell is preheated to 900°C-1000°C before casting, and the casting process is carried out under vacuum or inert gas protection.

[0029] The method provided by this invention has the following technical effects:

[0030] 1. A modified rare-earth master alloy is prepared by uniformly dispersing yttrium and magnesium as nanoscale precipitates within an aluminum-chromium matrix using a rapid melt solidification process. When this master alloy is added to a high-temperature nickel-based alloy melt, the magnesium preferentially vaporizes and reacts with residual oxygen in the melt due to its higher chemical reactivity and vapor pressure. This process instantaneously creates a localized environment with extremely low oxygen concentration around the yttrium atoms, thereby kinetically inhibiting direct contact and reaction between yttrium and the ceramic mold shell. As a result, the probability of the melt being contaminated by oxide inclusions is significantly reduced. The oxidation-resistant nickel-based superalloy prepared using this method has higher purity, increasing the yield of the final cast aero-engine turbine blades from 40-50% to 65-70%, thus reducing manufacturing costs.

[0031] 2. By employing a modified rare-earth master alloy and incorporating it within a specific time window before casting, the severe burn-off problem caused by the reaction and volatilization of active elements in traditional processes was solved. This ensures that yttrium can be stably dissolved into the final antioxidant nickel-based superalloy with a controllable and high yield. When turbine blades made from this alloy operate at high temperatures, these fully and uniformly distributed yttrium atoms segregate at the interface between the oxide film and the alloy matrix, enhancing the bonding force between the two through the active element effect. Even when the engine undergoes severe start-stop thermal cycles, this protective alumina film remains intact and does not peel off. This directly extends the effective service life of the blades under harsh operating conditions and improves the overall reliability of the aero-engine. Attached Figure Description

[0032] Figure 1 This is a metallographic microstructure image of Embodiment 1 of the present invention;

[0033] Figure 2 This is a metallographic microstructure image of Comparative Example 1 of this invention. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0035] Some exemplary embodiments of the invention have been described for illustrative purposes. It should be understood that the invention may be implemented in other ways not specifically shown in the accompanying drawings.

[0036] This invention provides a nickel-based superalloy and its preparation method.

[0037] Chemical composition of the final alloy

[0038] The chemical composition of the antioxidant nickel-based superalloy, by mass percentage, consists of the base element Ni and the following alloying elements within the specified ranges: Cr 8.0% to 10.0%, Co 9.0% to 11.0%, W 9.5% to 10.5%, Al 5.0% to 6.0%, Ti 1.0% to 2.0%, Ta 2.5% to 3.5%, C 0.08% to 0.12%, and B 0.01% to 0.02%.

[0039] The alloy composition is characterized by the introduction of a modified rare earth master alloy, which is added to the final alloy at a rate of 0.1% to 0.3%.

[0040] Preparation of modified rare earth master alloys

[0041] The preparation of this intermediate alloy includes the following steps:

[0042] First, the raw materials are weighed according to specific mass percentages, including 35.0% to 45.0% Y, 5.0% to 8.0% Mg, 10.0% to 15.0% Cr, and the balance Al. During the charging operation, to reduce the volatilization loss of metallic Mg in the initial stage of heating, it is wrapped in Al foil and placed at the bottom of a water-cooled copper crucible, and then covered with Y and Cr on top.

[0043] Subsequently, the raw materials are placed in a vacuum arc melting furnace and melted under an argon protective atmosphere. To avoid macroscopic segregation caused by differences in element melting points and densities and to ensure uniform composition, the melted alloy ingot is repeatedly turned over and remelted at least four times, with each melting time lasting 2 to 5 minutes, ultimately yielding the master alloy ingot.

[0044] Next, the master alloy ingot undergoes remelting and rapid solidification. This step is carried out in a quartz nozzle crucible. First, the environment is evacuated to less than 0.005 Pa, and then the alloy ingot is heated to 1350°C to 1400°C by induction heating to obtain a homogeneous melt. This temperature range was chosen to ensure complete melting of the alloy while controlling the volatilization rate of Mg.

[0045] The final step is rapid solidification via strip casting. Driven by high-purity Ar gas pressure of 0.02 MPa to 0.05 MPa, the molten material is sprayed from a nozzle onto the surface of a water-cooled copper roller rotating at a high linear velocity of 25 m / s to 30 m / s. Upon contact with the copper roller, the molten material solidifies into a thin strip at an extremely high cooling rate. This rapid cooling process suppresses long-range atomic diffusion, resulting in a metastable microstructure with a matrix grain size of less than 5 μm and a yttrium-rich phase dispersed as nanoscale particles smaller than 500 nm. These strips are collected and broken up to obtain the modified rare-earth master alloy.

[0046] Preparation of the final antioxidant nickel-based superalloy

[0047] After obtaining the modified rare earth master alloy, the final oxidation-resistant nickel-based superalloy is prepared by vacuum induction melting (VIM) process, with the specific steps as follows:

[0048] Metal raw materials, excluding Al, Ti, and modified rare earth master alloys, are loaded into the crucible of a VIM furnace. A vacuum is drawn to below 0.1 Pa, and the furnace charge is heated to melt. After the charge is completely melted, the temperature is raised to 1550℃ to 1600℃ and held for 15 to 30 minutes for refining and degassing. During this process, a suitable amount of carbon (C) can be added to generate CO gas through a carbon-oxygen reaction, which is then extracted by the vacuum system to reduce the oxygen content in the melt. The main reaction formula is as follows:

[0049]

[0050] (Where [C] and [O] represent carbon and oxygen dissolved in the melt)

[0051] After refining, the melt temperature is lowered to 1450℃, at which point Al and Ti are added and dissolved uniformly using electromagnetic stirring. Adding them at this temperature is to reduce the oxidation loss of these two reactive elements.

[0052] The next step is as follows: 2 to 3 minutes before pouring, high-purity Ar gas is backfilled into the furnace to a pressure environment of 2000 Pa to 5000 Pa, and then a predetermined amount of modified rare earth master alloy is added. The purpose of this operation is twofold: first, to suppress the rapid volatilization of Mg in the master alloy using a slightly positive pressure environment; and second, to limit the interaction between the highly reactive Y and the crucible lining (usually...) by shortening the addition time. or (Base) undergoes harmful interfacial reactions, for example:

[0053]

[0054] Meanwhile, Mg in the master alloy preferentially reacts with residual oxygen in the melt at this stage, further purifying and protecting Y. The reaction formula is as follows:

[0055]

[0056] Finally, the melt temperature is adjusted to a pouring window of 1420°C to 1440°C, and the melt is poured into a ceramic mold preheated to 900°C to 1000°C. The pouring process is carried out under vacuum or inert gas protection. Through the above process, the sulfur content in the final alloy can be controlled below 0.001%, the phosphorus content less than 0.002%, the silicon content less than 0.05%, and the residual magnesium content is controlled within the range of 0.005% to 0.020%.

[0057] The nickel-based superalloy prepared by this invention, due to its high purity and optimized trace element content, can form a dense and stable protective oxide film under high-temperature service conditions through the reaction of Al in the alloy with oxygen in the external environment. The main formation reaction is as follows:

[0058]

[0059] The Y element in the alloy can significantly enhance this. The bonding force between the film and the alloy substrate.

[0060] Example 1

[0061] This embodiment provides an antioxidant nickel-based superalloy and its preparation method.

[0062] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0063] Yttrium (Y) 40.0%, Magnesium (Mg) 6.5%, Chromium (Cr) 12.5%, Aluminum (Al) 41.0%

[0064] Specific preparation steps:

[0065] P1. Weigh each raw material according to the above proportions. Wrap magnesium metal in aluminum foil and place it at the bottom of the water-cooled copper crucible in the vacuum arc melting furnace, then cover it with yttrium metal and chromium metal.

[0066] P2. Under an argon protective atmosphere, the raw materials in the furnace are subjected to electric arc melting. To ensure uniform composition, the alloy ingot formed after melting is repeatedly turned over and remelted 4 times, with each melting time being 3 minutes, to obtain the master alloy ingot.

[0067] P3. Place the master alloy ingot in a quartz nozzle crucible, evacuate to an ambient pressure of less than 0.005 Pa, and then heat the alloy ingot to 1380°C by induction heating to completely remelt it and obtain a homogeneous melt.

[0068] P4. Under the pressure of high-purity argon gas (0.035 MPa), the melt is sprayed from a nozzle onto the surface of a high-speed rotating water-cooled copper roller with a linear velocity of 28 m / s for single-roll rapid solidification. The resulting metal strip is collected and broken into fragments of 2-5 mm in size to obtain the modified rare earth master alloy.

[0069] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0070] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0071] Specific preparation steps:

[0072] S1. Put the metal raw materials (nickel, chromium, cobalt, tungsten, tantalum, carbon, boron) other than aluminum, titanium and modified rare earth master alloys into the crucible of the vacuum induction melting furnace, evacuate to below 0.1 Pa, and heat to melt.

[0073] S2. After the furnace charge is completely melted, raise the temperature to 1580℃ and hold for 20 minutes for refining and degassing. During the refining process, add an appropriate amount of carbon for deoxidation.

[0074] S3. Reduce the melt temperature to 1450℃, add aluminum and titanium, and use electromagnetic stirring to dissolve them evenly.

[0075] S4. Refill the furnace with high-purity argon gas to a pressure of 3500 Pa. 2.5 minutes before pouring, add 0.2% of modified rare earth master alloy to the melt.

[0076] S5. Adjust the melt temperature to 1430℃ and pour it into a ceramic mold shell preheated to 950℃.

[0077] Example 2

[0078] This embodiment provides an antioxidant nickel-based superalloy and its preparation method.

[0079] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0080] Yttrium (Y) 35.0%, Magnesium (Mg) 5.0%, Chromium (Cr) 10.0%, Aluminum (Al) 50.0%.

[0081] Specific preparation steps:

[0082] Steps P1-P4 are exactly the same as in Example 1.

[0083] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0084] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.1%, Nickel (Ni) 60.785% (balance).

[0085] Specific preparation steps:

[0086] Steps S1-S3 are exactly the same as in Example 1.

[0087] S4. Backfill the furnace with high-purity argon gas to a pressure of 3500 Pa. Two minutes before pouring, add 0.1% of modified rare earth master alloy to the melt.

[0088] S5. The steps are exactly the same as in Example 1.

[0089] Example 3

[0090] This embodiment provides an antioxidant nickel-based superalloy and its preparation method.

[0091] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0092] Yttrium (Y) 45.0%, Magnesium (Mg) 8.0%, Chromium (Cr) 15.0%, Aluminum (Al) 32.0%.

[0093] Specific preparation steps:

[0094] Steps P1-P4 are exactly the same as in Example 1.

[0095] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0096] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.3%, Nickel (Ni) 60.585% (balance).

[0097] Specific preparation steps:

[0098] Steps S1-S3 are exactly the same as in Example 1.

[0099] S4. Backfill the furnace with high-purity argon gas to a pressure of 3500 Pa. Three minutes before pouring, add 0.3% of modified rare earth master alloy to the melt.

[0100] S5. The steps are exactly the same as in Example 1.

[0101] Example 4

[0102] This embodiment provides an antioxidant nickel-based superalloy and its preparation method.

[0103] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0104] Yttrium (Y) 40.0%, magnesium (Mg) 6.5%, chromium (Cr) 12.5%, aluminum (Al) 41.0%.

[0105] Specific preparation steps:

[0106] Steps P1-P2 are exactly the same as in Example 1.

[0107] P3. Place the master alloy ingot in a quartz nozzle crucible, evacuate to an ambient pressure of less than 0.005 Pa, and then heat the alloy ingot to 1350℃ by induction heating to completely remelt it and obtain a homogeneous melt.

[0108] P4. Under the pressure of high-purity argon gas (0.035 MPa), the melt is sprayed from a nozzle onto the surface of a high-speed rotating water-cooled copper roller with a linear velocity of 25 m / s for single-roll rapid solidification. The resulting metal strip is collected and broken into fragments of 2-5 mm in size to obtain the modified rare earth master alloy.

[0109] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0110] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0111] Specific preparation steps:

[0112] Steps S1-S5 are exactly the same as in Example 1.

[0113] Example 5

[0114] This embodiment provides an antioxidant nickel-based superalloy and its preparation method.

[0115] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0116] Yttrium (Y) 40.0%, magnesium (Mg) 6.5%, chromium (Cr) 12.5%, aluminum (Al) 41.0%.

[0117] Specific preparation steps:

[0118] Steps P1-P4 are exactly the same as in Example 1.

[0119] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0120] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0121] Specific preparation steps:

[0122] Steps S1-S3 are exactly the same as in Example 1.

[0123] S4. Backfill the furnace with high-purity argon gas to a pressure of 5000 Pa. 2.5 minutes before pouring, add 0.2% of modified rare earth master alloy to the melt.

[0124] S5. Adjust the melt temperature to 1440℃ and pour it into a ceramic mold preheated to 950℃.

[0125] Comparative Example 1

[0126] This comparative example provides an antioxidant nickel-based superalloy and its preparation method.

[0127] (a) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0128] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Yttrium (Y) 0.08%, Magnesium (Mg) 0.013%, Nickel (Ni) 60.792% (balance).

[0129] Specific preparation steps:

[0130] Steps S1-S3 are exactly the same as in Example 1.

[0131] S4. Refill the furnace with high-purity argon gas to a pressure of 3500 Pa. 2.5 minutes before pouring, add the yttrium and magnesium blocks to the melt.

[0132] S5. The steps are exactly the same as in Example 1.

[0133] Comparative Example 2

[0134] This comparative example provides an antioxidant nickel-based superalloy and its preparation method.

[0135] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0136] Yttrium (Y) 40.0%, magnesium (Mg) 6.5%, chromium (Cr) 12.5%, aluminum (Al) 41.0%.

[0137] Specific preparation steps:

[0138] Steps P1-P2 are exactly the same as in Example 1.

[0139] P3. The master alloy ingot obtained in step P2 is remelted in an induction furnace to 1380°C under argon protection, and then poured into a graphite mold and cooled to room temperature in the furnace.

[0140] P4. The cooled ingot is mechanically crushed to obtain fragments with a size of 2-5 mm, which is the modified rare earth master alloy.

[0141] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0142] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0143] Specific preparation steps:

[0144] Steps S1-S5 are exactly the same as in Example 1.

[0145] Comparative Example 3

[0146] This comparative example provides an antioxidant nickel-based superalloy and its preparation method.

[0147] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0148] Yttrium (Y) 42.8%, Chromium (Cr) 13.4%, Aluminum (Al) 43.8% (balance).

[0149] Specific preparation steps:

[0150] P1. Weigh each raw material according to the above proportions and place them in the water-cooled copper crucible of the vacuum arc melting furnace.

[0151] Steps P2-P4 are exactly the same as in Example 1.

[0152] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0153] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0154] Specific preparation steps:

[0155] Steps S1-S5 are exactly the same as in Example 1.

[0156] Comparative Example 4

[0157] This comparative example provides an antioxidant nickel-based superalloy and its preparation method.

[0158] (a) Preparation of modified rare earth master alloys: Prepare the following raw materials by mass percentage:

[0159] Yttrium (Y) 40.0%, Magnesium (Mg) 6.5%, Chromium (Cr) 12.5%, Aluminum (Al) 41.0%

[0160] Specific preparation steps:

[0161] Steps P1-P4 are exactly the same as in Example 1.

[0162] (II) Preparation of antioxidant nickel-based superalloys: Prepare the following raw materials by mass percentage:

[0163] Chromium (Cr) 9.0%, Cobalt (Co) 10.0%, Tungsten (W) 10.0%, Aluminum (Al) 5.5%, Titanium (Ti) 1.5%, Tantalum (Ta) 3.0%, Carbon (C) 0.10%, Boron (B) 0.015%, Modified Rare Earth Master Alloy 0.2%, Nickel (Ni) 60.685% (balance).

[0164] Specific preparation steps:

[0165] S1. The steps are exactly the same as in Example 1.

[0166] S2. After all the furnace charge has melted, heat the furnace to 1580℃, add 0.2% of modified rare earth master alloy to the melt, and hold for 20 minutes for refining and degassing. During the refining process, add an appropriate amount of carbon for deoxidation.

[0167] S3. The steps are exactly the same as in Example 1.

[0168] S4. Refill the furnace with high-purity argon gas until the pressure reaches 3500 Pa.

[0169] S5. The steps are exactly the same as in Example 1.

[0170] To verify the effectiveness of this invention, the test samples were prepared as follows: Following the complete preparation process of Examples 1 to 5 and Comparative Examples 1 to 4, corresponding alloy ingots were prepared by vacuum induction melting and casting. Subsequently, each group of ingots underwent the same heat treatment regime (solution treatment + aging treatment), and then, through wire cutting and machining, were prepared into standard samples required for subsequent performance testing, which were sequentially labeled as NBOA001 to NBOA009. The following performance tests were then performed on all grouped samples.

[0171] I. High-Temperature Antioxidant Performance Test

[0172] The high-temperature oxidation resistance test was conducted according to the Chinese National Standard GB / T 13303-1991, "Determination of Oxidation Resistance of Steel," which is currently valid and applicable to high-temperature alloys. The prepared standard samples (20mm × 10mm × 3mm) were ground and polished to a mirror finish, cleaned, and dried before being placed in a high-temperature resistance furnace at 1100℃ for cyclic oxidation experiments. A discontinuous weighing method was used; after every 20 hours of heating, the samples were removed, air-cooled to room temperature, and weighed using an electronic balance with an accuracy of 0.01mg. The total oxidation time was 100 hours. The oxidation rate constant (Kp, unit: ...) was calculated by recording the mass change of the samples. ) and peeling amount per unit area ( Kp is used as a quantitative evaluation index. The smaller the Kp value, the slower and denser the oxide film growth rate, and the stronger the oxidation resistance of the alloy. The lower the amount of peeling, the stronger the bonding force between the oxide film and the substrate (i.e., the better the film adhesion). This directly corresponds to the fact that the surface protective layer of the turbine blade made of this alloy has a longer anti-peeling life and higher reliability under the thermal cycle conditions of repeated engine start-stop.

[0173] II. Interfacial Reaction and Inclusion Analysis

[0174] Interface reaction and inclusion analysis were conducted according to Method A (sulfides) and Method D (spherical oxides) of the Chinese National Standard GB / T 10561-2023 "Determination of Non-metallic Inclusion Content in Steel - Standard Rating Chart Microscopic Examination Method," which is currently in effect. Metallographic samples were prepared from cross-sections of each ingot group. After mechanical polishing, the non-metallic inclusions within the field of view were observed under an optical microscope at 100x magnification. The average size (μm) of oxide inclusions and the density (inclusions / cm²) of large inclusions larger than 50μm within the field of view were statistically analyzed as quantitative evaluation indicators. Smaller inclusion size and lower density indicate a weaker interface reaction between the active elements and the ceramic mold shell during the smelting process, resulting in higher alloy purity. This directly reflects the alloy's superior process compatibility during casting. Furthermore, since large inclusions are often the source of fatigue crack initiation, their reduction means that single-crystal blades made from this alloy have a longer fatigue life.

[0175] III. Alloy Composition and Yield Analysis

[0176] The alloy composition yield analysis was conducted in accordance with relevant current and valid chemical analysis standards, including the Chinese National Standard GB / T 20127.2-2006 "Determination of Trace Elements in Iron and Steel and Alloys - Part 2: Determination of Arsenic Content by Hydride Generation-Atomic Fluorescence Spectrometry". Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used for full elemental quantitative analysis of each ingot. The yield (%) of the key active element yttrium (Y) was calculated as (measured value / theoretical addition value) × 100%, and the residual amount (wt%) of magnesium (Mg) was used as quantitative evaluation indicators. A higher Y yield (closer to 100%) indicates less burn-off and volatilization during the smelting process, and more precise process control. A stable Mg residual amount within the range of 0.005%-0.020% demonstrates successful "sacrificial protection" without contaminating the alloy, directly corresponding to the high efficiency and stability of the preparation process.

[0177] IV. Casting Surface Quality and Yield

[0178] The evaluation of casting surface quality and yield was conducted according to the latest Chinese national standard GB / T 32252-2024 "General Technical Guidelines for Investment Casting Process," which is currently in effect and covers the latest surface quality acceptance specifications for investment castings. Each experimental group simulated the precision casting process, casting 50 blade samples. After standard sandblasting, a visual inspection was first performed to assess surface sand adhesion. Subsequently, high-sensitivity fluorescent penetrant testing (FPI) was conducted according to GB / T 18851.1-2024 "Non-destructive Testing - Penetrant Testing Part 1: General Rules" to detect minute cracks. The average area percentage (%) of surface sand adhesion defects and the first-pass yield (%) meeting the acceptance requirements of GB / T 32252-2024 were used as quantitative evaluation indicators for each group of samples. The lower the proportion of sand adhering area, the weaker the chemical erosion of the ceramic shell by the alloy melt, and the more effectively the interfacial reaction is suppressed; the higher the first-pass yield, the fewer scraps caused by inclusions, cracks or surface defects, which directly corresponds to the fact that this alloy technology can significantly reduce manufacturing costs and improve production efficiency in large-scale industrial production.

[0179] The test results are summarized in the following two tables.

[0180] Table 1

[0181]

[0182] Table 2

[0183]

[0184] 1. Antioxidant performance analysis

[0185] The test results in Table 1 show that the oxidation rate constant Kp values ​​of the groups in the embodiments of the present invention are all very low. The yttrium content was between 7.0 g / m², and the amount of oxide film peeling per unit area was also less than 7.0 g / m². This indicates that the yttrium element introduced through the modification of the rare earth master alloy did indeed form a dense protective film on the alloy surface and effectively enhanced the film's adhesion.

[0186] However, in Comparative Example 1, which uses the traditional direct addition method, the Kp value reached... The amount of yttrium exfoliated also surged to 18.5 g / m². This is because during its preparation, most of the yttrium was consumed through direct contact and reaction with the ceramic shell, resulting in insufficient effective yttrium content dissolved in the matrix, thus failing to maintain a long-lasting antioxidant effect. Comparative Example 4 was even worse; due to its premature addition, almost all the active elements were burned off, resulting in the worst antioxidant performance.

[0187] 2. Interfacial Reaction and Inclusion Analysis

[0188] Instruction manual attached Figure 1 and attached Figure 2 The metallographic photographs directly explain the reasons for the aforementioned performance differences. (Attached) Figure 1 Example 1 shows a very clean metal matrix containing only a few tiny spherical particles with a size of 2-3 μm. This is consistent with the low inclusion density (1.2 inclusions / cm²) and tiny size (3.5 μm) of the NBOA001 sample in Table 1. This demonstrates that magnesium in the modified rare earth master alloy preferentially reacts with oxygen, and the resulting tiny magnesium oxide particles do not cause fragmentation of the matrix.

[0189] Appendix Figure 2 The situation in (Comparative Example 1) is completely different; large, angular inclusions exceeding 50 μm in size can be clearly seen. These inclusions are the exfoliation products resulting from the violent chemical reaction between yttrium and the ceramic shell. Table 1 confirms this, showing that the density of large inclusions in Comparative Example 1 is as high as 12.8 inclusions / cm², more than 10 times that of Example 1. These large inclusions are a major cause of blade fatigue failure.

[0190] 3. Alloy composition yield analysis

[0191] The yttrium recovery rate directly reflects the effectiveness of the process. Table 2 shows that the yttrium recovery rate in the example group of this invention was consistently around 90%, but in Comparative Example 1 it was only 55.4%, and in Comparative Example 4 it was as low as 38.2%. This proves that the combined process of "modified intermediate alloy, micro-positive pressure argon gas protection, and late addition" can indeed protect the highly reactive yttrium element, allowing it to quickly dissolve into the matrix before being oxidized or reacting with the shell.

[0192] Furthermore, the residual magnesium content in the example group was precisely controlled within the designed range of 0.008%-0.019%. This data indicates that magnesium played a "sacrificial protection" role and did not contaminate the alloy. Comparative Example 3, which contained no magnesium, showed a significant decrease in yttrium yield to 68.5%, which in turn proves the necessity of magnesium in the formulation.

[0193] 4. Casting surface quality and yield

[0194] Due to the improved alloy purity and the suppression of interfacial reactions, the sand adhesion area on the casting surface of the embodiment group of this invention is controlled to within 3%, far lower than the 12.5% ​​of Comparative Example 1. Better surface quality directly leads to a higher yield. The first-pass yield of the casting in the embodiment group is significantly improved to 66%-74%, nearly double that of the traditional process (42% of Comparative Example 1). This indicates that the technical solution of this invention has excellent potential for industrial application and large-scale production.

[0195] In summary, this invention, through a unique modified rare earth master alloy design and supporting preparation process, resolves the contradiction between "addition of active elements" and "compatibility with casting processes" in nickel-based superalloys, achieving comprehensive improvements in oxidation resistance, alloy purity, and casting yield.

[0196] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An antioxidant nickel-based superalloy, characterized in that, The chemical composition of the antioxidant nickel-based superalloy, by mass percentage, includes: Chromium 8.0%-10.0%, Cobalt 9.0%-11.0%, Tungsten 9.5%-10.5%, Aluminum 5.0%-6.0%, Titanium 1.0%-2.0%, Tantalum 2.5%-3.5%, Carbon 0.08%-0.12%, Boron 0.01%-0.02%, Modified Rare Earth Master Alloy 0.1%-0.3%, Balance: Nickel and unavoidable impurities; The preparation of the modified rare earth master alloy includes the following steps: P1. Weigh out yttrium, magnesium, chromium and aluminum as raw materials according to the mass ratio; P2. The raw material is placed in a water-cooled copper crucible in a vacuum arc melting furnace and repeatedly turned and melted under an argon protective atmosphere to obtain a master alloy ingot. P3. Place the master alloy ingot in a quartz nozzle crucible and induction heat it to 1350℃-1400℃ under a vacuum of less than 0.005Pa to remelt it and obtain a homogeneous melt; P4. The uniform melt is sprayed onto the surface of a high-speed rotating water-cooled copper roller with a linear velocity of 25-30 m / s using gas pressure for single-roller fast solidification, and then collected and crushed to obtain the modified rare earth intermediate alloy. The antioxidant nickel-based superalloy is prepared by vacuum induction melting combined with precision casting. During the preparation process, the modified rare earth master alloy is added to the alloy melt 2-3 minutes before pouring, under an environment where argon gas is backfilled in the furnace to a pressure of 2000Pa-5000Pa. The raw materials for preparing the modified rare earth master alloy in step P1, by mass percentage, include: Yttrium 35.0%-45.0%, magnesium 5.0%-8.0%, chromium 10.0%-15.0%, balance aluminum.

2. The antioxidant nickel-based superalloy according to claim 1, characterized in that, The matrix grain size in the modified rare earth master alloy is less than 5 μm, and the yttrium-rich phase is dispersed in the aluminum matrix in the form of nano-precipitates less than 500 nm.

3. The antioxidant nickel-based superalloy according to claim 1, characterized in that, Of the unavoidable impurities, the sulfur content is less than 0.001%, the phosphorus content is less than 0.002%, the silicon content is less than 0.05%, and the residual magnesium content in the antioxidant nickel-based superalloy is 0.005%-0.020%.

4. The antioxidant nickel-based superalloy according to claim 1, characterized in that, In step P1, magnesium metal is wrapped in aluminum foil and placed at the bottom of the crucible, covered with yttrium metal and chromium metal.

5. The antioxidant nickel-based superalloy according to claim 1, characterized in that, In step P2, the melting process is repeated at least 4 times, and each melting process takes 2-5 minutes.

6. The antioxidant nickel-based superalloy according to claim 1, characterized in that, In step P4, the gas medium for the injection pressure is high-purity argon, and the injection pressure is controlled between 0.02 and 0.05 MPa.

7. A method for preparing an antioxidant nickel-based superalloy as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Except for aluminum, titanium, and modified rare earth master alloys, other metallic raw materials are loaded into the crucible of the vacuum induction melting furnace according to the specified proportions, and a vacuum is drawn until... Next, heat and melt; S2. After all the furnace charge has melted, raise the temperature to 1550℃-1600℃ for refining and degassing; S3. Cool to 1450℃, add aluminum and titanium, and perform electromagnetic stirring; S4. Refill the furnace with argon gas to a pressure of 2000Pa-5000Pa, and add the modified rare earth master alloy 2-3 minutes before pouring; S5. Adjust the melt temperature to 1420℃-1440℃ and pour it into a preheated ceramic mold.

8. The preparation method according to claim 7, characterized in that, The refining and degassing time in step S2 is 15-30 minutes, and an appropriate amount of carbon is added during the refining process for deoxidation.

9. The preparation method according to claim 7, characterized in that, The ceramic mold shell is preheated to 900℃-1000℃ before casting, and the casting process is carried out under vacuum or inert gas protection.

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