A low-density and high-strength nickel-based superalloy, its preparation method and application

Abstract

The present invention relates to a low-density and high-strength nickel-based superalloy, its preparation method and application. The chemical composition percentage of the low-density and high-strength nickel-based superalloy is as follows: Al: 4.5-5.5 wt%, Co: 15.5-16.55 wt%, Cr: 11.0-12.0 wt%, Mo: 0.3-0.7 wt%, Ti: 4.5-5.5 wt%, W: 2.0-3.0 wt%, C: 0.05-0.15 wt%, and the balance is Ni; the Al / Ti in the alloy is between 0.8-1.2, and Al + Ti ≤ 10 wt%; it has fine γ' phase and residual eutectic phase, and the density is 7.90-7.95 g / cm<supgt;3< / supgt;. This alloy has high room-temperature tensile mechanical properties. After hot isostatic pressing and homogenization treatment, the yield strength is not less than 695 MPa, the tensile strength is not less than 1008 MPa, and the elongation after fracture is higher than 24%. It is suitable for applications such as preparing blades or turbine disks of heavy-duty gas turbines and aeroengines.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature alloys, and particularly relates to a low-density and high-strength nickel-based superalloy and its preparation and application. Background Art

[0002] Nickel-based superalloys refer to metallic materials with nickel as the matrix that can work for a long time at high temperatures above 600°C under certain stress. They have excellent high-temperature strength, good oxidation and hot corrosion resistance, good fatigue performance, fracture toughness and other comprehensive properties, and are mainly used in the aerospace and energy fields. The requirements for the temperature-bearing capacity and mechanical properties of superalloys as aeroengine materials are constantly increasing. Nickel-based superalloys have a high volume fraction of γ' phase, which exists in the alloy in the form of cubic blocks and has a coherent interface with the continuous face-centered cubic γ-phase matrix, showing as narrow channels between the γ' phase blocks. The highly ordered L12 structure gives the γ' phase high strength and low dislocation tolerance, and dislocation movement is mainly restricted within the γ-phase matrix channels. Therefore, nickel-based superalloys have high high-temperature strength and creep resistance. On the other hand, density is also a key issue restricting the application of superalloys. High-density superalloys will inevitably increase the weight of the engine under a certain volume, and then generate greater stress in the turbine blades or turbine disks. The influence of density must be considered during the design process. Therefore, it is necessary to reduce the density of nickel-based superalloys as much as possible while ensuring strength. Currently, some advanced superalloy materials have the ability to maintain high strength at relatively high temperatures. For example, the equilibrium content of the γ' phase in GH4975 alloy at 760°C is as high as 63%, and it can be used for a long time in the range of 800-900°C, and can maintain excellent comprehensive properties for a long time above 850°C. However, its W content is very high, reaching 10%, and the alloy density is relatively high. Summary of the Invention

[0003] This embodiment discloses a low-density and high-strength nickel-based superalloy and its preparation and application to solve the above technical problems and other technical problems in the prior art.

[0004] To solve the above technical problems, the technical solution of the present invention is: a low-density and high-strength nickel-based superalloy, and the chemical composition mass percentages of the low-density and high-strength nickel-based superalloy are: Al: 4.5-5.5wt%, Co: 15.5-16.55wt%, Cr: 11.0-12.0wt%, Mo: 0.3-0.7wt%, Ti: 4.5-5.5wt%, W: 2.0-3.0wt%, C: 0.05-0.15wt%, and the balance is Ni.

[0005] Further, the Al / Ti in the low-density and high-strength nickel-based superalloy is between 0.8 and 1.2, and Al + Ti ≤ 10wt%.

[0006] Furthermore, the low-density and high-strength nickel-based superalloy has fine γ' phases and residual eutectic phases, and its density is 7.90 - 7.95 g / cm 3 .

[0007] Furthermore, the tensile yield strength of the low-density and high-strength nickel-based superalloy is not less than 695 MPa, the tensile strength is not less than 1008 MPa, and the elongation after fracture is higher than 24%.

[0008] Furthermore, the chemical composition of the low-density and high-strength nickel-based superalloy by mass percentage is: 59.4 wt% Ni, 16.0 wt% Co, 11.5 wt% Cr, 0.5 wt% Mo, 5.0 wt% Ti, 5.0 wt% Al, 0.1 wt% C, 2.5 wt% W, and its density is 7.93 g / cm 3 , the yield strength of the alloy is 715 MPa, the tensile strength is 1080 MPa, the elongation is 25%, the compressive yield strength is 1078 MPa, and the Vickers hardness HV0.5 is 435.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned low-density and high-strength nickel-based superalloy, and the method specifically includes the following steps:

[0010] S1) Raw material preparation: Weigh each raw material according to the designed ratio, and reserve it after pretreatment;

[0011] S2) Melting and preparation: Place each raw material after being processed by S1) into a copper crucible of a WK series small vacuum arc furnace for melting to obtain a low-density and high-strength nickel-based superalloy ingot; at this time, the ingot has columnar crystals, and the grain size perpendicular to the direction of the columnar crystals is concentrated in the range of 200 - 300 μm, and a few grains are larger than 400 μm; the types of precipitate phases in the as-cast alloy are few, mainly composed of primary γ' phases and petal-shaped eutectic phases;

[0012] Its as-cast tensile yield strength is not less than 921 MPa, the elongation after fracture is not less than 2.5%, and the tensile strength is not less than 962 MPa; the compressive yield strength is not less than 1067 MPa, no fracture failure occurs during the compression process, and the Vickers hardness HV0.5 is not less than 424.

[0013] S3) Perform homogenization heat treatment on the low-density and high-strength nickel-based superalloy ingot obtained in S2), and then perform hot isostatic pressing treatment to obtain the low-density and high-strength nickel-based superalloy.

[0014] Furthermore, each raw material in S1) is in block form; the pretreatment process is: place it in absolute ethanol for ultrasonic oscillation cleaning to remove the impurities on the surface, and reserve it after drying.

[0015] Further, the specific process in S2) is as follows:

[0016] S2.1) Before melting, the vacuum degree in the vacuum arc furnace is pumped to below 5×10 -3 Pa, and the current during melting is 320A - 350A;

[0017] S2.2) When the first melting is completed, the workpiece is turned over, and the melting is repeated at least 6 times.

[0018] Further, in S3):

[0019] S3.1) The temperature of homogenization heat treatment is 1170°C - 1190°C, the treatment time is 18 - 22 hours, and it is air-cooled;

[0020] S3.2) The temperature of hot isostatic pressing is 1170°C - 1190°C, the pressure is 140 - 160 MPa, and the time is 1.5 - 2.5 hours.

[0021] A low-density and high-strength nickel-based superalloy prepared by the above method is applied to the fields of heavy aero-engines and gas turbines.

[0022] The main alloying elements contained in the low-density and high-strength nickel-based superalloy of the present invention are Al, Co, Cr, Mo, Ti, W, and C. Among them, Al is the basic component element for forming the γ'-Ni3Al phase, mainly playing a precipitation strengthening role, and at the same time can significantly reduce the density of the alloy; Ti entering the γ matrix can play a solid solution strengthening role, and entering the γ' phase can replace the Al atoms therein, playing a precipitation strengthening role, and can also increase the number of carbides; in view of the fact that Al and Ti can directly affect the volume fraction of the γ' phase and significantly reduce the alloy density, but excessive addition will promote the formation of the γ / γ' eutectic structure between dendrites. Therefore, the mass percentages of Al and Ti elements in this alloy are both controlled at 4.5 - 5.5%, the Al / Ti is between 0.8 - 1.2, and Al + Ti ≤ 10 wt%; Cr is a solid solution strengthening element and a carbide-forming element, and can also improve the oxidation and corrosion resistance of the alloy, but excessive Cr will promote the precipitation of the topologically close-packed phase (TCP phase). Therefore, the Cr content is controlled at 11.0 - 12.0%; Co can play a solid solution strengthening role, and can also reduce the stacking fault energy of the alloy matrix, improve the medium-temperature performance of the alloy, and improve the tissue stability. Therefore, the content is controlled at 15.5 - 16.5%; Mo and W can also play a solid solution strengthening role, but excessive amounts will increase the alloy density and promote the precipitation of the TCP phase. Therefore, the Mo content is controlled at 0.3 - 0.7%, and the W content is controlled at 2.0 - 3.0%; the trace element C can control the grain size or strengthen the grain boundary, and the content is controlled at 0.05 - 0.15%.

[0023] Optionally, the density of the low-density and high-strength nickel-based superalloy is 7.90-7.95 g / cm 3 , since the sum of the contents of Al and Ti reaches about 10 wt%, and the contents of the high-density alloying elements W and Mo are strictly controlled, the density is significantly lower than that of alloys such as GH4975, GH1451, AD730, GH4169, and GH4738.

[0024] Beneficial effects of the present invention: Due to the above technical solution, the density of the low-density and high-strength nickel-based superalloy of the present invention is 7.90-7.95 g / cm 3 , and the density is significantly lower than that of alloys such as GH4975, GH4151, AD730, GH4169, and GH4738. This alloy has high room-temperature tensile mechanical properties. The as-cast tensile yield strength is not less than 921 MPa, the elongation after fracture is not less than 2.5%, and the tensile strength is not less than 962 MPa; no fracture failure occurs during the compression process, and the Vickers hardness HV0.5 is not less than 424. After hot isostatic pressing and heat treatment, the tensile yield strength can reach 695 MPa, the tensile strength reaches 1008 MPa, and the elongation after fracture is higher than 24%. The phase composition of this alloy is reasonable. The initial melting point and the final melting point are about 1280 °C and 1328 °C respectively. The temperature at which the main strengthening phase γ' phase completely dissolves back is about 1215 °C. Above 740 °C, the equilibrium phases are only γ, γ', MC and M 23 C6, and the equilibrium content of the main strengthening phase γ' phase can reach 66% at 800 °C. Description of the Drawings

[0025] Figure 1 It is the as-cast microstructure morphology of the low-density and high-strength nickel-based superalloy prepared by melting in a small vacuum arc furnace in Example 1.

[0026] (a, b) are 500x; (c) is 10000x; (d) is 30000x.

[0027] Figure 2 It is the as-cast EBSD image of the low-density and high-strength nickel-based superalloy in Example 1.

[0028] (a) is 50x parallel to the direction of columnar crystals; (b) is 50x perpendicular to the direction of columnar crystals.

[0029] Figure 3 It is the phase diagram of the low-density and high-strength nickel-based superalloy in Example 1.

[0030] Figure 4 It is the DSC test result of the low-density and high-strength nickel-based superalloy in Example 1.

[0031] Figure 5Schematic diagram of the microstructure morphology after homogenization of the low-density and high-strength nickel-based superalloy in Example 1.

[0032] (a) Remaining eutectic, 2000x (b) γ' phase, 10000x.

[0033] Figure 6 Schematic diagram of the stress-strain curve of the as-cast room-temperature compression test of the low-density and high-strength nickel-based superalloy in Example 1.

[0034] Figure 7 Schematic diagram of the stress-strain curves of the room-temperature tensile tests of the low-density and high-strength nickel-based superalloy in two states in Example 1.

[0035] Figure 8 Schematic diagram of the as-cast microstructure morphology of the low-density and high-strength nickel-based superalloy in Example 2.

[0036] Figure 9 Schematic diagram of the stress-strain curve of the as-cast room-temperature tensile test of the low-density and high-strength nickel-based superalloy in Example 2.

[0037] Figure 10 Schematic diagram of the optical microscope of the microstructure morphology after homogenization of the low-density and high-strength nickel-based superalloy in Example 3. Detailed implementation manners

[0038] The technical solutions of the present invention will be further described below in conjunction with specific embodiments and the accompanying drawings.

[0039] A low-density and high-strength nickel-based superalloy of the present invention, the chemical composition mass percentages of the low-density and high-strength nickel-based superalloy are: Al: 4.5-5.5 wt%, Co: 15.5-16.55 wt%, Cr: 11.0-12.0 wt%, Mo: 0.3-0.7 wt%, Ti: 4.5-5.5 wt%, W: 2.0-3.0 wt%, C: 0.05-0.15 wt%, and the balance is Ni. The Al / Ti in the low-density and high-strength nickel-based superalloy is between 0.8-1.2, and Al + Ti ≤ 10 wt%.

[0040] The low-density and high-strength nickel-based superalloy has fine γ' phases and remaining eutectic phases, and the density is 7.90-7.95 g / cm 3 .

[0041] The as-cast tensile yield strength of the low-density and high-strength nickel-based superalloy is not less than 921 MPa, the elongation after fracture is not less than 2.5%, and the tensile strength is not less than 962 MPa; no fracture failure occurs during the compression process, and the Vickers hardness HV0.5 is not less than 424; after hot isostatic pressing and homogenization treatment, the tensile yield strength is not less than 695 MPa, the tensile strength is not less than 1008 MPa, and the elongation after fracture is higher than 24%.

[0042] The chemical composition of the low-density and high-strength nickel-based superalloy is as follows by mass percentage: 59.4 wt% Ni, 16.0 wt% Co, 11.5 wt% Cr, 0.5 wt% Mo, 5.0 wt% Ti, 5.0 wt% Al, 0.1 wt% C, 2.5 wt% W, and its density is 7.93 g / cm 3 ;

[0043] A method for preparing the above low-density and high-strength nickel-based superalloy, the method specifically includes the following steps:

[0044] S1) Raw material preparation: Weigh each raw material according to the designed ratio, and reserve it after pretreatment;

[0045] S2) Melting preparation: Put each raw material after S1) treatment into a copper crucible of a WK series small vacuum arc furnace for melting to obtain a low-density and high-strength nickel-based superalloy ingot; at this time, the ingot has columnar crystals, and the grain size perpendicular to the direction of the columnar crystals is concentrated in the range of 200 - 300 μm, and a few grains are larger than 400 μm; the types of precipitate phases in the as-cast alloy are few, mainly composed of primary γ' phase and petal-shaped eutectic phases, as Figure 1 and Figure 2 shown;

[0046] S3) Perform homogenization heat treatment on the low-density and high-strength nickel-based superalloy ingot obtained in S2), and then perform hot isostatic pressing treatment to obtain the low-density and high-strength nickel-based superalloy.

[0047] Each raw material in S1) is in block form; the pretreatment process is: put it into absolute ethanol for ultrasonic oscillation cleaning, remove the impurities on the surface, and reserve it after drying.

[0048] The specific process in S2) is as follows:

[0049] S2.1) Before melting, evacuate the vacuum degree in the vacuum arc furnace to below 5×10 -3 Pa, and the current during melting is 320 A - 350 A;

[0050] S2.2) Turn over the ingot during the first melting, and melt it at least 6 times repeatedly.

[0051] In S3):

[0052] S3.1) The temperature of homogenization heat treatment is 1170°C to 1190°C, the treatment time is 18 - 22 hours, and it is air-cooled;

[0053] S3.2) The temperature of hot isostatic pressing is 1170°C to 1190°C, the pressure is 140 - 160 MPa, and the time is 1.5 - 2.5 hours.

[0054] A low-density and high-strength nickel-based superalloy prepared by the above method is applied to the fields of heavy aero-engines and gas turbines.

[0055] Example 1:

[0056] The chemical composition mass percentage of the low-density and high-strength nickel-based superalloy is 59.4 wt% Ni - 16.0 wt% Co - 11.5 wt% Cr - 0.5 wt% Mo - 5.0 wt% Ti - 5.0 wt% Al - 0.1 wt% C - 2.5 wt% W.

[0057] Raw material preparation: Calculate and weigh a certain amount of raw material blocks of Al, Co, Cr, Mo, Ti, W, Ni, and C. Use sandpaper to grind off the surface impurities and oxide scales generated by cutting on the raw material blocks. Then, accurately weigh the required mass of the raw materials on a balance. Subsequently, all the weighed raw materials are placed in anhydrous ethanol for ultrasonic vibration cleaning to remove surface impurities, and then dried;

[0058] Smelting preparation: Place the raw materials into a copper crucible of a small vacuum arc furnace to smelt and obtain a new nickel-based superalloy. The current requirement during smelting is 320 A. Before smelting, the vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa. Each time after smelting, it needs to be turned over, and smelted repeatedly for 6 times to obtain the ingot of this alloy;

[0059] Table 1 shows the density results tested three times by the Archimedes method. It can be seen that the density of the alloy is 7.93 g / cm 3 , which is significantly lower than alloys such as GH4975, GH4169, and GH4738. Figure 1 is the as-cast microstructure morphology of the new nickel-based superalloy prepared by smelting with a small vacuum arc furnace. Obvious dendritic structures can be seen; there are fewer types of precipitate phases, which are composed of γ' phase and eutectic phase. The γ' phase is relatively fine, with a size of about 100 nm, and the eutectic phase presents a petal shape and has a larger size. Figure 2 is the EBSD image of the as-cast alloy. The observation results are divided into the direction parallel to the columnar crystal and the direction perpendicular to the columnar crystal. The results show that the alloy ingot has columnar crystals. The grain size in the direction perpendicular to the columnar crystal is concentrated in the range of 200 - 300 μm, and a few grains are larger than 400 μm. In contrast, the grain size of the GH4975 alloy is the largest.

[0060] Table 1 Test Results of Alloy Density

[0061]

[0062] Figure 3 is the phase diagram of the new nickel-based superalloy, Figure 4 is the DSC test result of the new nickel-based superalloy. According to this result, it can be seen that the initial melting point and final melting point of the alloy are about 1280 °C and 1328 °C respectively, the solidification temperature range is small, and the initial melting point of the alloy is relatively close to that of ЭК151 alloy; the temperature at which the main strengthening phase γ′ phase completely dissolves back is about 1215 °C, and the re-dissolution process of the γ′ phase is accompanied by the remelting of the γ+γ′ eutectic phase. The homogenization process of the superalloy needs to comprehensively consider issues such as eliminating segregation, melting of low-melting-point regions, grain growth, and oxidation. The homogenization temperature cannot be set too high; and the secondary dendrite arm spacing of the ingot does not exceed 30 μm. Therefore, the homogenization temperature is set to 1170 °C - 1190 °C, the time is about 20 hours, and air cooling is used. Figure 5 is the microstructure morphology of the new nickel-based superalloy after homogenization heat treatment at 1180 °C for 20 hours and air cooling. It can be seen that the dendrite morphology is not obvious, only a small amount of γ+γ′ eutectic structure remains, the primary γ′ phase partially dissolves back, and the size of the γ′ phase slightly decreases.

[0063] Table 2 shows the results of three Vickers hardness (HV0.5) tests on different parts of the as-cast new nickel-based superalloy. It can be found that the hardness value of the alloy is relatively high, and the average HV0.5 reaches more than 430.

[0064] Table 2 Test Results of Alloy Vickers Hardness HV0.5

[0065]

[0066] The stress-strain curve of the as-cast room-temperature compression test is as Figure 6 shown, the strain rate is 0.001 s -1 , and the results show that its compressive yield strength reaches 1067 MPa and no fracture occurs during the entire compression test. Through homogenization heat treatment and hot isostatic pressing (HIP), the process of hot isostatic pressing is to process at 1170 °C for 4 hours, the homogenization heat treatment temperature is 1170 °C, the time is 20 hours and air cooling is used to eliminate casting defects. Then, the tensile properties of the as-cast, HIP + homogenized alloys are tested, and the strain rate is 0.001 s -1 , and the room-temperature tensile test results are as Figure 7 shown, the strain rate is 0.001 s -1, the results show that the yield strength and tensile strength of the as-cast alloy reach 931 MPa and 964 MPa respectively, and the elongation after fracture is 2.5%. Due to some casting defects during the preparation process, the elongation of the as-cast alloy is relatively low, but the yield strength of the alloy still shows a relatively high level in the as-cast state. After hot isostatic pressing and homogenization heat treatment, the yield strength of the alloy is 695 MPa, which decreases, but the elongation after fracture exceeds 24%, and the tensile strength exceeds 1008 MPa.

[0067] Example 2:

[0068] The chemical composition of the low-density high-strength nickel-based superalloy in mass percentage is 59.78Ni - 15.5Co - 12.0Cr - 0.7Mo - 4.5Ti - 5.5Al - 0.05C - 2.0W;

[0069] Raw material preparation: Calculate and take a certain amount of raw material blocks of Al, Co, Cr, Mo, Ti, W, Ni, and C. Use sandpaper to polish off the surface impurities and oxide scales generated by cutting on the raw material blocks. Then, accurately weigh the required mass of the raw materials on a balance. Subsequently, all the weighed raw materials are placed in absolute ethanol for ultrasonic vibration cleaning to remove surface impurities, and then dried;

[0070] Smelting preparation: Place the raw materials into a copper crucible of a small vacuum arc furnace to smelt and obtain a new nickel-based superalloy. The current requirement during smelting is 320 A. Before smelting, the vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa. Each time after smelting is completed, it needs to be turned over, and smelted repeatedly 6 times to obtain the ingot of this alloy;

[0071] Figure 8 is the morphology of the as-cast microstructure of the new nickel-based superalloy, and obvious dendritic structures can be seen.

[0072] The stress-strain curve of the as-cast room-temperature tensile test is as Figure 9 shown, the strain rate is 0.001 s -1 , and the results show that its tensile yield strength is 921 MPa, the tensile strength is 962 MPa, the elongation after fracture is 3.3%, and the density of the alloy is 7.95 g / cm 3 .

[0073] Example 3:

[0074] The chemical composition of the low-density high-strength nickel-based superalloy in mass percentage is 58.9Ni - 16.5Co - 11.0Cr - 0.3Mo - 4.8Ti - 5.3Al - 0.15C - 3.0W;

[0075] Raw material preparation: Calculate and weigh a certain amount of raw material blocks of Al, Co, Cr, Mo, Ti, W, Ni, and C. Use sandpaper to polish off the surface impurities and oxide scales generated by cutting on the raw material blocks. Subsequently, accurately weigh the required mass of the raw materials on a balance. Then, place all the weighed raw materials in anhydrous ethanol for ultrasonic oscillation cleaning to remove surface impurities, and perform drying treatment;

[0076] Smelting preparation: Place the raw materials into a copper crucible of a small vacuum arc furnace for smelting to obtain a new nickel-based superalloy. The current requirement during smelting is 320 A. Before smelting, the vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa. Each time after smelting is completed, it is necessary to turn over, and smelt repeatedly 6 times to obtain the ingot of this alloy;

[0077] Homogenization heat treatment: The temperature is 1180 °C, and homogenization heat treatment is carried out for 18 hours and then air-cooled. Figure 10 is the microstructure morphology after homogenization heat treatment of the new nickel-based superalloy. It can be seen that the dendritic morphology is relatively indistinct, and only a small amount of γ+γ′ eutectic structure remains. The density of the alloy is 7.93 g / cm 3 .

[0078] The above has introduced in detail a low-density and high-strength nickel-based superalloy and its preparation method and application provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0079] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "comprising" and "including" are open-ended terms, so they should be interpreted as "comprising / including but not limited to". "Roughly" means within an acceptable error range. Those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description in the specification is the preferred implementation manner for implementing the present application, but the description is for the purpose of explaining the general principle of the present application and is not used to limit the scope of the present application. The protection scope of the present application shall be subject to what is defined by the appended claims.

[0080] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such commodity or system. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the commodity or system comprising said element.

[0081] It should be understood that the term "and / or" used herein is merely a description of the associated relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0082] The above description shows and describes several preferred embodiments of the present application. However, as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A low-density and high-strength nickel-based superalloy, characterized in that, The chemical composition of the low-density and high-strength nickel-based superalloy in mass percentage is as follows: Al: 4.5-5.5 wt%, Co: 15.5-16.55 wt%, Cr: 11.0-12.0 wt%, Mo: 0.3-0.7 wt%, Ti: 4.5-5.5 wt%, W: 2.0-3.0 wt%, C: 0.05-0.15 wt%, and the balance is Ni; In the low-density and high-strength nickel-based superalloy, the ratio of Al / Ti is between 1 and 1.2, and 9 wt% ≤ Al + Ti ≤ 10 wt%; The low-density and high-strength nickel-based superalloy has residual eutectic phases and fine γ' phases; The density of the low-density and high-strength nickel-based superalloy is 7.90 - 7.95 g / cm 3 ; The tensile yield strength of the low-density and high-strength nickel-based superalloy is not less than 695 MPa, the tensile strength is not less than 1008 MPa, and the elongation after fracture is higher than 24%.

2. The low-density and high-strength nickel-based superalloy according to claim 1, characterized in that, The chemical composition of the low-density and high-strength nickel-based superalloy is as follows by mass percentage: 59.4 wt% Ni, 16.0 wt% Co, 11.5 wt% Cr, 0.5 wt% Mo, 5.0 wt% Ti, 5.0 wt% Al, 0.1 wt% C, 2.5 wt% W, and its density is 7.93 g / cm 3 , the tensile yield strength of the alloy is 715 MPa, the tensile strength is 1080 MPa, the elongation is 25%, the compressive yield strength is 1078 MPa, and the Vickers hardness HV0.5 is 435.

3. A method for preparing the low-density and high-strength nickel-based superalloy according to any one of claims 1 or 2, characterized in that, The method specifically includes the following steps: S1) Raw material preparation: Weigh each raw material according to the designed ratio, and reserve it after pretreatment; The pretreatment process is: Place it in absolute ethanol for ultrasonic oscillation cleaning to remove the impurities on the surface, and reserve it after drying; S2) Melting and preparation: Put each raw material after being processed in S1) into a vacuum smelting device for melting to obtain a low-density and high-strength nickel-based superalloy ingot; S3) Perform homogenization heat treatment on the low-density and high-strength nickel-based superalloy ingot obtained in S2), and then perform hot isostatic pressing treatment to obtain the low-density and high-strength nickel-based superalloy.

4. The method according to claim 3, characterized in that, The specific melting process in S2) is as follows: S2.1) Before melting, the vacuum degree in the vacuum arc furnace is pumped to below 5×10 -3 Pa, and the current during melting is 320A - 350A; S2.2) When the alloy melting is completed for one melting, turn over the obtained ingot and melt it again, and repeat the melting at least 6 times.

5. The method according to claim 3, characterized in that, In S3): S3.1) The temperature of the homogenization heat treatment is 1170°C to 1190°C, the treatment time is 18-22 hours, and air cooling is carried out; S3.2) The temperature of the hot isostatic pressing is 1170°C to 1190°C, the pressure is 140-160 MPa, and the time is 1.5-2.5 hours.

6. A low-density and high-strength nickel-based superalloy prepared by the method according to any one of claims 3-5 is applied to prepare blades or turbine disks of heavy-duty gas turbines and aeroengines.

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