A high-strength low-density fe-ni-based high-entropy high-temperature alloy with spherical gamma-prime coherent strengthening and a preparation method thereof

Abstract

A high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement and its preparation method are disclosed. Belonging to the field of high-entropy superalloys, the alloy comprises Fe, Ni, Co, Al, Ti, Nb, Cr, Mo, C, B, and Zr elements. The mass percentages of the alloy composition are as follows: Ni: 29.8–33.2, Co: 13.3–16.7, Al: 2.7–3.1, Ti: 2.1–3.3, Nb: 1.0–2.1, Cr: 12.0–13.9, Mo: 1.4–1.7, C: 0.01–0.03, B: 0.005–0.015, Zr: 0.02–0.03, Fe: balance. The atomic percentage of Al / (Ti+Nb) is 1–2, and the atomic ratio of Cr / Mo is 15:1. This invention achieves coherent precipitation of spherical γ′ nanoparticles on a γ matrix through alloy composition design. The γ′ nanoparticles remain stable at 750℃ for extended periods, resulting in an alloy with excellent mechanical properties and processing deformability. Its room temperature yield strength exceeds 820 MPa, room temperature elongation exceeds 20%, and its yield strength at 700℃ exceeds 710 MPa. Furthermore, the high Fe content effectively reduces the alloy's cost, the preparation process is simple, and the density is below 7.80 g / cm³. 3 It is a high-strength, low-density Fe-Ni based high-entropy superalloy.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy superalloys, and specifically relates to a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement. Its microstructure is characterized by spherical γ′-(Ni,Fe,Co)3(Al,Ti,Nb) nanoparticles coherently precipitated on a face-centered cubic FCC-γ matrix. Furthermore, the γ′ nanoparticles do not exhibit significant coarsening after long-term aging at 750℃, demonstrating high high-temperature structural stability. Simultaneously, high-density elements such as W and Ta are eliminated, and the addition of low-density elements Al and Ti results in an alloy density ≤7.80 g / cm³. 3 . Background Technology

[0002] High-temperature alloys refer to metallic materials based on Fe, Co, and Ni that can operate for extended periods at temperatures above 600°C and under certain stresses. Ni-based high-temperature alloys, in particular, possess excellent high-temperature mechanical properties and creep resistance, and are widely used in aerospace engines and industrial gas turbines. This is primarily due to their unique microstructure, namely the coherent precipitation of spherical or square L12-γ′ nanoparticles in a face-centered cubic (FCC)-γ matrix. With the continuous development of aerospace technology, the service temperature of hot-end components such as turbine disks has exceeded 700°C. To meet their performance requirements, various alloying elements are often added to high-temperature alloys used in turbine disks, such as solid solution strengthening elements (Cr, Mo, W), precipitation strengthening elements (Al, Ti, Nb, Ta), and grain boundary strengthening elements (C, B, Zr). However, high alloying not only increases the alloy's manufacturing cost but also places high demands on smelting and hot-working technologies. Furthermore, the addition of heavy elements such as W and Ta significantly increases the alloy's density. Currently, Inconel 718, a commonly used material in domestic aero-engines, possesses excellent processing and deformation capabilities due to its high Nb content (4.75–5.50 wt.%). This results in slow Nb diffusion, a slow nucleation rate of the precipitated phase, a low precipitation temperature, and a large hot working window. However, it is prone to alloy composition segregation. Furthermore, when the operating temperature of Inconel 718 exceeds 650℃, the main strengthening phase transforms from a tetragonal γ″-Ni3Nb structure to an orthorhombic δ-Ni3Nb structure, losing its coherent relationship with the matrix FCC phase and significantly reducing alloy performance. Inconel 718Plus alloy, through replacing Fe with Co, increasing W, and raising Al, precipitates ordered L12-γ′ nanoparticles on the FCC-γ matrix, forming a γ / γ′ coherent structure with high high-temperature structural stability, thereby increasing the alloy's temperature resistance to 700℃. However, its processing and deformation capabilities are weakened, especially the elongation after fracture of cold-rolled sheets is <10%. Additionally, the addition of heavy elements such as W reduces its density (8.36 g / cm³). 3 )Increase.

[0003] Therefore, achieving coherent precipitation of γ′ nanoparticles on an FCC-γ matrix while ensuring their long-term stability in high-temperature service environments, while reducing the alloy's density and cost, is one of the key issues for the development and application of this type of alloy. In view of this, this invention provides a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement. Summary of the Invention

[0004] This invention provides a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement and its preparation method. Compared with existing superalloys, this alloy has a density ρ≤7.80g / cm³. 3 The higher iron content effectively reduces the cost of this series of alloys, and the γ / γ′ coherent structure remains stable after long-term aging at 750℃. The objective of this invention is to design a low-density, low-cost, high-strength, high-entropy high-temperature alloy for aerospace applications through alloy composition design.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement is provided. The high-strength, low-density Fe-Ni-based high-entropy superalloy is composed of two coherent phases, γ and γ′. The matrix is ​​an FCC-γ solid solution structure, and the precipitated phase is an ordered superstructure of FCC-γ solid solution, namely γ′-(Ni,Fe,Co)3(Al,Ti,Nb). The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement comprises Fe, Ni, Co, Al, Ti, Nb, Cr, Mo, C, B, and Zr elements, with the following mass percentages (wt.%): Ni: 29.8–33.2, Co: 13.3–16.7, Al: 2.7–3.1, Ti: 2.1–3.3, Nb: 1.0–2.1, Cr: 12.0–13.9, Mo: 1.4–1.7, C: 0.01–0.03, B: 0.005–0.015, Zr: 0.02–0.03, Fe: balance, and the atomic ratio of Al / (Ti+Nb) is 1–2, and the atomic ratio of Cr / Mo is 15:1.

[0007] The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement exhibits a specific microstructure: spherical γ′-(Ni,Fe,Co)3(Al,Ti,Nb) nanoparticles coherently precipitate on the FCC-γ matrix. These γ′ nanoparticles do not undergo significant coarsening after long-term aging at 750℃, demonstrating high high-temperature microstructure stability, thus resulting in excellent high-temperature mechanical properties. The alloy density ρ ≤ 7.80 g / cm³. 3This is much smaller than that of representative wrought high-temperature alloys, such as In 718 alloy (8.24 g / cm³). 3 ) and In 718Plus alloy (8.36g / cm) 3 Meanwhile, the higher iron content effectively reduces the density and cost of this series of alloys.

[0008] A method for preparing a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent strengthening includes the following steps: First, each alloy component is melted at least four times in a vacuum arc melting process according to its mass percentage to obtain an alloy ingot; second, the alloy ingot is homogenized in a muffle furnace at a temperature of 1150–1200℃ for 4–8 hours, followed by water quenching, and then subjected to multi-pass unidirectional cold rolling with a single reduction of 0.1–1 mm and a total reduction of 85–90%; finally, after solution treatment at 1000℃ for 15 minutes, it is aged at 750℃ for 24–500 hours and then water quenched to obtain a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent strengthening.

[0009] The concept for achieving the above technical solution is as follows:

[0010] The applicant's cluster-based compositional design method was used to design the composition of high-strength, low-density Fe-Ni-based high-entropy superalloys. This method divides the solid solution alloy structure into two parts: clusters and connecting atoms. A cluster refers to a nearest-neighbor coordination polyhedron formed around any given atom. For FCC-structured alloys, the clusters are cubic octahedrons with a coordination number of CN12. When these isolated clusters are stacked to form the entire structural space, the interstitial positions between the clusters are filled by connecting atoms. Generally, solute atoms with strong interactions with the matrix solvent atoms preferentially occupy the central positions of the clusters, while solvent atoms occupy the shell positions, thus representing the strongest short-range chemical properties. Solute atoms with weak interactions with the matrix are typically located at the connecting atom positions.

[0011] Therefore, in Fe-Ni based high-entropy superalloys, elements can be divided into three categories based on their roles in the alloy: Al-based elements (… Ti, Nb, Ta), Cr series elements ( Mo, W), and Ni-based elements ( (Co, Fe, etc.); among which, Al-based elements and Ni-based elements have strong interactions, so Al-based elements preferentially occupy the central atomic positions of the clusters, while Cr-based elements, which have relatively weak interactions with the matrix, occupy the connecting atomic positions. This yields the ideal cluster composition formula for Fe-Ni based high-entropy superalloys.

[0012] In Fe-Ni based high-entropy superalloys, Al-based elements are all γ′ phase-forming elements. At high temperatures, Al can form a dense Al₂O₃ protective film on the alloy surface, playing a crucial role in the alloy's oxidation resistance. Simultaneously, Al's low density helps reduce the alloy's overall density. The addition of Ti and Nb increases the volume fraction of the γ′ phase and raises its dissolution temperature, but this also increases the difficulty of alloy deformation. Excessive Ti content can also lead to the formation of the harmful η phase, while excessive Nb content can cause severe segregation and the formation of the harmful δ phase. To meet the alloy's high strength and low density requirements, the atomic percentage ratio of Al / (Ti+Nb) must be maintained at 1–2 while limiting its content. Cr-based elements play a role in solid solution strengthening. At high temperatures, Cr can form a Cr₂O₃ protective film on the alloy surface, improving the alloy's oxidation resistance and hot corrosion resistance. However, excessive Cr content can easily lead to the precipitation of the σ phase, reducing the alloy's structural stability. Mo can also reduce the alloy's notch sensitivity, but excessive addition can lead to the precipitation of harmful phases such as topologically close-packed phases (TCP). Therefore, Mo is added to replace Cr in the clusters according to an atomic ratio of 15:1. Ni-based elements can improve matrix stability, while a small amount of Co can reduce matrix stacking fault energy and significantly improve the alloy's creep strength and creep resistance while maintaining cost. Adding Fe can reduce alloy cost, but excessive addition will reduce alloy strength and creep performance. Additionally, adding C can refine grains, but excessive C will reduce the alloy's weldability and plasticity; therefore, C addition is controlled between 0.01 and 0.03 wt.%. The addition of trace elements B (0.005–0.015 wt.%) and Zr (0.02–0.03 wt.%) can improve grain boundary bonding and increase the alloy's high-temperature strength. Finally, we determined the composition of a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement as Fe-(29.8~33.2)Ni-(13.3~16.7)Co-(2.7~3.1)Al-(2.1~3.3)Ti-(1.0~2.1)Nb-(12.0~13.9)Cr-(1.4~1.7)Mo-(0.01~0.03)C-(0.005~0.015)B-(0.02~0.03)Zr (wt.%).

[0013] The preparation method of this invention is as follows: High-purity metal materials are used and proportioned according to mass percentage. The proportioned materials are melted repeatedly at least four times in a vacuum non-consumable arc furnace under argon atmosphere protection to obtain an alloy ingot with a uniform composition and a mass of 120g, with a mass loss of no more than 0.1% during the melting process. The alloy ingot is homogenized in a muffle furnace at a temperature of 1150-1200℃ for 4-8 hours, followed by water quenching, and then subjected to multi-pass unidirectional cold rolling with a single reduction of 0.1-1mm and a total reduction of 85-90%. Finally, after solution treatment at 1000℃ for 15 minutes, it is aged at 750℃ for 24-500 hours and then water quenched to obtain a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent strengthening. The density of the alloy was determined using a densitometer (XS64); the density of Cu K alloy was determined using metallographic microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). α The microstructure and structure of the alloy were detected by radiation (λ = 0.15406 nm); the hardness of the series alloys under different heat treatment conditions was tested using an HVS-1000 Vickers hardness tester; and the tensile mechanical properties at room temperature and 700℃ were tested using a UTM5504 electronic universal tensile testing machine. Based on these findings, the present invention is determined to be a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ′ coherent reinforcement, as described above. The alloy composition (wt.%) is as follows: Ni: 29.8–33.2, Co: 13.3–16.7, Al: 2.7–3.1, Ti: 2.1–3.3, Nb: 1.0–2.1, Cr: 12.0–13.9, Mo: 1.4–1.7, C: 0.01–0.03, B: 0.005–0.015, Zr: 0.02–0.03, Fe: balance. The atomic ratio of Al / (Ti+Nb) is 1–2, and the atomic ratio of Cr / Mo is 15:1. After aging at 750℃ (24–500 h), spherical γ′ nanoparticles (20–90 nm) coherently precipitate on the FCC-γ matrix, exhibiting higher high-temperature structural stability. The material's performance indicators are: room temperature hardness HV = 390–430 kgf·mm. -2 room temperature yield strength σ s ≥820MPa, tensile strength σ b ≥1200MPa, elongation after fracture δ≥20%; yield strength σ at 700℃ s ≥710MPa, tensile strength σ b ≥800MPa, elongation after fracture δ≥20%; density of the alloy ρ≤7.80g / cm³ 3 .

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) This invention designs and develops a high-strength, low-density Fe-Ni-based high-entropy high-temperature alloy with spherical γ′ coherent reinforcement based on the applicant's independently developed cluster composition method. Compared with existing high-temperature alloys, the alloy density of this invention is ρ≤7.80g / cm³. 3 This is much smaller than that of representative high-temperature alloys such as In 718 alloy (8.24 g / cm³). 3 ) and In718Plus alloy (8.36g / cm) 3 Meanwhile, the higher Fe content effectively reduces the cost of this series of alloys.

[0016] (2) The microstructure of this series of alloys is characterized by the coherent precipitation of spherical γ′-(Ni,Fe,Co)3(Al,Ti,Nb) nanoparticles on an FCC-γ matrix. The γ′ nanoparticles are uniformly distributed on the matrix with a volume fraction >30%. During deformation, the dislocation shear mechanism is dominant. Furthermore, the γ′ nanoparticles do not undergo significant coarsening after long-term aging at 750℃, exhibiting high high-temperature microstructure stability. Moreover, the high-temperature yield strength σ of this series of alloys at 700℃ is also high. s ≥710MPa, elongation after fracture δ≥20%. Attached Figure Description

[0017] Figure 1 and Figure 2 SEM microstructure of the alloy prepared in Example 1: Figure 1 The microstructure is shown after aging at 750℃ for 24 hours, i.e., spherical γ′ nanoparticles are coherently precipitated on the FCC-γ matrix, and the γ′ nanoparticles are approximately 28 nm in size. Figure 2 The microstructure is shown after aging at 750℃ for 500h, i.e., spherical γ′ nanoparticles are coherently precipitated on the FCC-γ matrix, and the γ′ nanoparticles are approximately 61nm in size. Detailed Implementation

[0018] The specific embodiments of the present invention will be described in detail below with reference to the technical solution.

[0019] Example 1: Fe-33.17Ni-13.35Co-3.06Al-2.17Ti-1.05Nb-13.80Cr-1.70Mo-0.03C-0.015B-0.03Zr (wt.%) alloy, with an Al / (Ti+Nb) atomic ratio of 2:1 and a Cr / Mo atomic ratio of 15:1;

[0020] Step 1: Alloy Preparation

[0021] High-purity metal materials were used and proportioned according to mass percentages. The materials were repeatedly melted five times in a vacuum non-consumable arc furnace under argon atmosphere protection to obtain a 120g alloy ingot with uniform composition, with a mass loss not exceeding 0.1% during the melting process. The alloy ingot was then solution-treated at 1200℃ for 4 hours in a muffle furnace, followed by water quenching. The purpose of solution treatment was to reduce or eliminate component segregation and dissolve unevenly precipitated phases. Subsequently, multiple cold rolling passes were performed, with a single reduction of 0.8mm and a total reduction of 90%. Finally, after solution treatment at 1000℃ for 15 minutes, the ingot was aged at 750℃ for 24 hours, followed by water quenching.

[0022] Step 2: Testing of alloy microstructure and mechanical properties

[0023] The microstructure and structure of the alloy after aging were detected using OM, SEM, and XRD. The results showed that the alloy microstructure of the present invention consisted of spherical γ′ nanoparticles coherently precipitated on a γ matrix, and these γ′ nanoparticles could remain stable for a long time at a high temperature of 750℃. After aging for 24 hours, the size of the γ′ nanoparticles was 28 nm. The microstructure morphology is shown in the attached figure. Figure 1 As shown; the hardness was tested using a Vickers hardness tester, and the result was HV = 396 kgf·mm. -2 Mechanical property data at room temperature were obtained using a UTM5504 electronic universal tensile testing machine: yield strength σ s =850MPa, tensile strength σ b =1233MPa, elongation after fracture δ=22%; Mechanical property data at 700℃: yield strength σ s =714MPa, tensile strength σ b =807MPa, elongation after fracture δ = 24%; the alloy density ρ, measured using a densitometer (XS64), is 7.71g / cm³. 3 .

[0024] Example 2: Fe-29.84Ni-16.65Co-2.74Al-2.70Ti-1.05Nb-13.77Cr-1.69Mo-0.02C-0.01B-0.03Zr (wt.%) alloy, with an Al / (Ti+Nb) atomic ratio of 3:2 and a Cr / Mo atomic ratio of 15:1;

[0025] Step 1: Alloy Preparation

[0026] High-purity metal materials were used and proportioned according to mass percentages. The materials were repeatedly melted six times in a vacuum non-consumable arc furnace under argon atmosphere protection to obtain a 120g alloy ingot with uniform composition, with a mass loss not exceeding 0.1% during the melting process. The alloy ingot was then solution-treated in a muffle furnace at 1150℃ for 8 hours, followed by water quenching. The purpose of solution treatment was to reduce or eliminate component segregation and dissolve unevenly precipitated phases. Subsequently, multiple cold rolling passes were performed, with a single reduction of 0.5mm and a total reduction of 88%. Finally, after solution treatment at 1000℃ for 15 minutes, the ingot was aged at 750℃ for 200 hours, followed by water quenching.

[0027] Step 2: Testing of alloy microstructure and mechanical properties

[0028] The microstructure and structure of the alloy after aging treatment were detected using OM, SEM, and XRD. The results showed that the alloy microstructure of the present invention consisted of cubic γ′ nanoparticles coherently precipitated on a γ matrix, and these γ′ nanoparticles could remain stable for a long time at a high temperature of 750℃. Similar to Example 1, the size of the γ′ nanoparticles was 50 nm after aging for 200 h. The hardness was tested using a Vickers hardness tester and the result was HV = 392 kgf·mm. -2 Mechanical property data at room temperature were obtained using a UTM5504 electronic universal tensile testing machine: yield strength σ s =826MPa, tensile strength σ b =1211MPa, elongation after fracture δ=27%; Mechanical property data at 700℃: yield strength σ s =736MPa, tensile strength σ b =840MPa, elongation after fracture δ =22%; the alloy density ρ, measured using a densitometer (XS64), is 7.73g / cm³. 3 .

[0029] Example 3: Fe-31.45Ni-14.96Co-2.74Al-2.97Ti-1.57Nb-13.20Cr-1.62Mo-0.01C-0.005B-0.02Zr (wt.%) alloy, with an Al / (Ti+Nb) atomic ratio of 9:7 and a Cr / Mo atomic ratio of 15:1;

[0030] Step 1: Alloy Preparation

[0031] High-purity metal materials were batched according to mass percentages. The batched materials were repeatedly melted four times in a vacuum non-consumable arc furnace under argon atmosphere protection to obtain a 120g alloy ingot with uniform composition, with a mass loss not exceeding 0.1% during the melting process. The alloy ingot was then solution-treated at 1200℃ for 6 hours in a muffle furnace, followed by water quenching. The purpose of solution treatment was to reduce or eliminate component segregation in the microstructure and dissolve unevenly precipitated phases. Subsequently, multiple cold rolling passes were performed, with a single reduction of 0.2mm and a total reduction of 85%. Finally, after solution treatment at 1000℃ for 15 minutes, the ingot was aged at 750℃ for 100 hours, followed by water quenching.

[0032] Step 2: Testing of alloy microstructure, mechanical properties, and corrosion resistance

[0033] The microstructure and structure of the alloy after aging treatment were detected using OM, SEM, and XRD. The results showed that the alloy microstructure of the present invention consisted of cubic γ′ nanoparticles coherently precipitated on a γ matrix, and these γ′ nanoparticles could remain stable for a long time at a high temperature of 750℃. Similar to Example 1, the size of the γ′ nanoparticles was 42 nm after aging for 100 h. The hardness was tested using a Vickers hardness tester, and the hardness HV was 410 kgf·mm. -2 Mechanical property data at room temperature were obtained using a UTM5504 electronic universal tensile testing machine: yield strength σ s =898MPa, tensile strength σ b =1343MPa, elongation after fracture δ=24%; Mechanical property data at 700℃: yield strength σ s =776MPa, tensile strength σ b =920MPa, elongation after fracture δ=21%; the alloy density ρ, measured using a densitometer (XS64), is 7.72g / cm³. 3 .

[0034] Example 4: Fe-33.09Ni-16.61Co-3.04Al-3.24Ti-2.10Nb-12.09Cr-1.49Mo-0.02C-0.005B-0.02Zr (wt.%) alloy, with an Al / (Ti+Nb) atomic ratio of 5:4 and a Cr / Mo atomic ratio of 15:1;

[0035] Step 1: Alloy Preparation

[0036] High-purity metal materials were batched according to mass percentages. The batched materials were repeatedly melted eight times in a vacuum non-consumable arc furnace under argon atmosphere protection to obtain a 120g alloy ingot with uniform composition, with a mass loss not exceeding 0.1% during the melting process. The alloy ingot was then solution-treated in a muffle furnace at 1150℃ for 8 hours, followed by water quenching. The purpose of solution treatment was to reduce or eliminate component segregation in the microstructure and dissolve unevenly precipitated phases. Subsequently, multiple cold rolling passes were performed, with a single reduction of 0.1mm and a total reduction of 85%. Finally, after solution treatment at 1000℃ for 15 minutes, the ingot was aged at 750℃ for 50 hours, followed by water quenching.

[0037] Step 2: Testing of alloy microstructure, mechanical properties, and corrosion resistance

[0038] The microstructure and structure of the alloy after aging treatment were detected using OM, SEM, and XRD. The results showed that the alloy microstructure of the present invention consisted of cubic γ′ nanoparticles coherently precipitated on a γ matrix, and these γ′ nanoparticles could remain stable for a long time at a high temperature of 750℃. Similar to Example 1, the size of the γ′ nanoparticles was 46 nm after aging for 50 h. The hardness was tested using a Vickers hardness tester and the result was HV = 428 kgf·mm. -2 Mechanical property data at room temperature were obtained using a UTM5504 electronic universal tensile testing machine: yield strength σ s =960MPa, tensile strength σ b =1462MPa, elongation after fracture δ=20%; Mechanical property data at 700℃: yield strength σ s =803MPa, tensile strength σ b =926MPa, elongation after fracture δ=20%; the alloy density ρ, measured using a densitometer (XS64), is 7.69g / cm³. 3 .

[0039] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement, characterized in that, The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement comprises Fe, Ni, Co, Al, Ti, Nb, Cr, Mo, C, B, and Zr elements, with the following mass percentages (wt.%): Ni: 29.8~33.2, Co: 13.3~16.7, Al: 2.7~3.1, Ti: 2.1~3.3, Nb: 1.0~2.1, Cr: 12.0~13.9, Mo: 1.4~1.7, C: 0.01~0.03, B: 0.005~0.015, Zr: 0.02~0.03, Fe: balance, and the atomic ratio of Al / (Ti+Nb) is 1~2, and the atomic ratio of Cr / Mo is 15:

1.

2. The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement according to claim 1, characterized in that, The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement has a specific microstructure: spherical γ´-(Ni,Fe,Co)3(Al,Ti,Nb) nanoparticles are coherently precipitated on the FCC-γ matrix, and the spherical γ´-(Ni,Fe,Co)3(Al,Ti,Nb) nanoparticles do not undergo significant coarsening after long-term aging at 750℃, exhibiting high microstructure stability.

3. The high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement according to claim 2, characterized in that, The typical properties of the high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement are: density ≤ 7.80 g / cm³. 3 The room temperature yield strength is ≥820MPa, the room temperature elongation is ≥20%, and the high temperature yield strength at 700℃ is ≥710MPa.

4. A method for preparing a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent reinforcement as described in any one of claims 1-3, characterized in that, The process includes the following steps: First, each alloy component is melted at least four times in a vacuum arc melting process according to its mass percentage to obtain a homogeneous alloy ingot; second, the alloy ingot is homogenized in a muffle furnace at a temperature of 1150~1200℃ for 4~8h, followed by water quenching, and then subjected to multiple passes of unidirectional cold rolling with a single reduction of 0.1~1mm and a total reduction of 85~90%; finally, after solution treatment at 1000℃ / 15min, it is aged at 750℃ for 24~500h and then water quenched to obtain a high-strength, low-density Fe-Ni-based high-entropy superalloy with spherical γ´ coherent strengthening.

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