A low-density, 750-degree-Celsius-resistant Ni-Co-Fe-Cr-based deformed high-entropy high-temperature alloy and a preparation method thereof

Abstract

The application discloses a low-density Ni-Co-Fe-Cr-based deformed high-entropy high-temperature alloy resistant to 750 DEG C and a preparation method thereof. The alloy comprises Ni, Co, Fe, Cr, Mo, Al, Ti, Nb, C, B and Zr, and the alloy composition wt.% is as follows: Co is 12-25, Fe is 8.5-17.5, Cr is 15.5-17.0, Mo is 2.0-3.5, Al is 1.5-3, Ti is 2-4, Nb is 0-5.7, C is 0.01-0.05, B is 0.005-0.02, Zr is 0.01-0.03, and Ni is the balance. The atomic percentage ratio of (Ti+Nb) / Al is 0.8-2, and the atomic percentage ratio of Cr / Mo is 9-14.5. The alloy obtained by the application has good mechanical properties and excellent processing deformation capacity, the room-temperature yield strength is greater than 1100 MPa, the room-temperature plasticity is greater than 15%, and the 750 DEG C yield strength is greater than 950 MPa.

Description

Technical Field

[0001] This invention belongs to the field of wrought high-entropy high-temperature alloys, and in particular, a low-density, 750℃-resistant wrought high-strength high-temperature high-entropy alloy and its preparation method. It can maintain the stability of the γ / γ′ coherent structure after long-term aging at 750℃, the γ′ particle coarsening rate is extremely low, and the high-temperature strength at this temperature exceeds 950MPa. Background Technology

[0002] With the development of aerospace technology, the thrust-to-weight ratio of aircraft is gradually increasing, thus placing higher demands on high-performance metallic structural materials, especially the development of high-performance high-temperature alloys. High-temperature alloys refer to those based on Fe, Co, and Ni, typically operating at temperatures above 650℃ and under certain stress conditions. This places stringent requirements on the comprehensive properties of these alloys. High-temperature alloys must possess high high-temperature strength, good plasticity, resistance to high-temperature oxidation, corrosion resistance, and long-term thermal stability. To improve the service performance of alloys and meet high-temperature strength requirements, alloying elements such as Ni, Co, Cr, Mo, W, Al, Ti, Nb, and Ta are added to high-performance wrought high-temperature alloys. However, high alloying not only increases the alloy's manufacturing cost but also increases the difficulty of alloy processing deformation and microstructure control. Furthermore, the addition of high-density elements such as W and Ta increases the alloy's density.

[0003] The highly alloyed state results in a high alloy density, typically around 8.2 g / cm³. 3 The above is an example. For instance, In 718, a representative wrought high-temperature alloy, possesses excellent processing and deformation capabilities. However, the operating temperature of In 718 alloy is limited to 650℃. Once the temperature rises, a phase transformation occurs, and the main strengthening phase, the tetragonal γ″-Ni3Nb, transforms into the orthorhombic δ-Ni3Nb. Due to the loss of coherence with the matrix FCC-γ phase, the alloy's performance is significantly reduced. Subsequently, In 718 Plus alloys, by adding heat-resistant elements such as Co and W, and simultaneously increasing the Al content, precipitate ordered L12-γ′ nanoparticles on the FCC-γ matrix, forming a high-temperature stable FCC-γ / γ′ coherent structure, thereby increasing the alloy's temperature resistance to 700℃. However, its processing and deformation capabilities are weaker than those of In. 718, especially the elongation after fracture of cold-rolled sheets is <10%; the Ni-Co based TMW high-temperature alloy developed by the National Institute for Materials Science in Japan can withstand temperatures up to 725℃, with a Co content of 20-31 wt.%, a Ti content of 5.1-7.4 wt.%, and a W content of 1.0-2.0 wt.%, which improves the alloy's temperature resistance to a certain extent. However, when the Ti content exceeds 6.0 wt.%, the harmful η-Ni3Ti phase precipitates, affecting the alloy's performance, and the alloy's density is >8.0 g / cm³. 3Furthermore, with its γ′ particle content reaching 45-50%, the γ′ phase precipitation temperature is high and the hot working window is narrow, placing it within the category of difficult-to-deform high-temperature alloys. Simultaneously, the high alloying states of existing high-temperature alloys increasingly limit the compositional range of each element, making it difficult to achieve qualitative breakthroughs in performance, especially in high-temperature performance exceeding 750℃, simply by adjusting element content.

[0004] Therefore, three core issues restricting the development of current wrought superalloys are: firstly, the large number of alloying elements in current superalloys makes their microstructure and properties sensitive to the alloy composition, making it difficult to expand the composition range of existing elements; secondly, ensuring low density while maintaining high temperature resistance (750℃) and microstructure stability; and thirdly, ensuring excellent deformability while improving the high-temperature performance of the alloy. In view of this, this invention provides a low-density, 750℃-resistant Ni-Co-Fe-Cr-based wrought high-entropy superalloy and its preparation method, with an alloy density ≤7.9 g / cm³. 3 It can maintain its hardness essentially unchanged before long-term aging at 750℃, and the coarsening rate of γ′ particles is extremely low with no harmful phase precipitation. The room temperature yield strength is >1100MPa, tensile strength is >1450MPa, room temperature elongation is >15%, and high temperature yield strength at 750℃ is >950MPa. Summary of the Invention

[0005] This invention provides a low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy and its preparation method. Compared with existing cast-forged deformable superalloys and high-entropy alloys, this alloy has a density ≤7.9 g / cm³. 3 The alloy exhibits a room temperature yield strength >1100 MPa, tensile strength >1450 MPa, room temperature elongation >15%, and a high-temperature yield strength >950 MPa at 750℃, with extremely low γ′ particle coarsening rate and no harmful phase precipitation. The purpose of this invention is to develop a novel deformable high-entropy superalloy for components such as aero-engine turbine disks and gas turbine blades through precise alloy design, resulting in lower density and higher temperature resistance.

[0006] The technical solution of this invention is:

[0007] A low-density, 750℃-resistant Ni-Co-Fe-Cr-based high-entropy superalloy is characterized in that the low-density, 750℃-resistant high-entropy superalloy comprises Ni, Co, Fe, Cr, Mo, Al, Ti, Nb, C, B, and Zr elements, with the following mass percentages (wt.%): Co: 12-25, Fe: 8.5-17.5, Cr: 15.5-17.0, Mo: 2.0-3.5, Al: 1.5-3, Ti: 2-4, Nb: 0-5.7, C: 0.01-0.05, B: 0.005-0.02, Zr: 0.01-0.03, Ni: balance, and the atomic percentage ratio of (Ti+Nb) / Al is 0.8-2, and the atomic percentage ratio of Cr / Mo is 9-14.5.

[0008] Furthermore, in the aforementioned high-entropy superalloy, γ′ particles coherently precipitate on the FCC-γ matrix, with a total γ′ phase volume percentage of 30–40%, and contain a very small amount of carbides dispersed at the grain boundaries. After long-term aging at 750℃, it exhibits excellent γ / γ′ coherent structure stability: the γ′ particles show no significant coarsening, and the γ′ particle coarsening rate K ≤ 0.1 nm. 3 With no other harmful phases precipitating, this alloy exhibits excellent high-temperature structural stability, good mechanical properties, and superior processing and deformation capabilities.

[0009] Furthermore, the low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy has the following typical properties: density ≤ 7.9 g / cm³. 3 Room temperature yield strength > 1100 MPa, tensile strength > 1450 MPa, room temperature elongation > 15%, high temperature yield strength at 750℃ > 950 MPa, hardness HV ≥ 420 kgf·mm before and after long-term aging at 750℃. -2 It exhibits excellent high-temperature structural stability.

[0010] A method for preparing a low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy includes the following steps:

[0011] Step 1: Weigh the high-purity alloy material according to the mass percentage, and add it to the vacuum arc melting furnace according to the principle of lower melting point at the bottom and higher melting point at the top. Melt it repeatedly at least several times, and turn on the electromagnetic stirring system 8 to 10 times during the process without opening the furnace door in the middle to ensure that the alloy ingot composition is uniform.

[0012] Step 2: Melt it using a vacuum electric arc tilting casting furnace and then tilt it to cast a rectangular plate;

[0013] Step 3: Homogenize the alloy ingot using a muffle furnace at 1200–1250℃ for 2–4 hours, then air-cool it for 1–5 minutes before water-cooling it to room temperature. Subsequently, perform multiple passes of unidirectional cold rolling, with a single reduction of 0.1–0.5 mm and a total reduction of 80–90%, to obtain a cold-rolled sheet with a thickness of 1–2 mm. Finally, after solution treatment at 1050–1070℃ for 0.5–1 hour, water-cool it, and then age it at 740–760℃ for 20–28 hours before water-cooling to obtain the final product.

[0014] The concept behind the above technical solution is to utilize the applicant's cluster-based composition design method to design the composition of a novel low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy. This method constructs cluster-based structural units based on inter-element interactions, forming [clusters] (connecting atoms). x A cluster is composed of a group of atoms and x connecting atoms. The group is a coordination polyhedron formed by any solute atom at its center and surrounded by matrix atoms in the nearest-neighbor shell. The connecting atoms in the next nearest-neighbor shell are used to match the average density of the alloy. For FCC-based alloy systems, the cluster is typically a cubic octahedron with a coordination number of CN12, and the number of connecting atoms is usually x = 3 to 5. This cluster-based composition design method has been successfully applied to the design of various engineering alloys, such as high-temperature austenitic stainless steel, low-elasticity β-Ti alloys, and Co-based high-temperature alloys, providing new ideas and methods for the composition design of high-performance engineering alloys. Meanwhile, the high-entropy alloys proposed in recent years have broadened the composition range of alloy design, allowing alloys to no longer use a single element as the main element, but rather multiple principal elements. Therefore, the concept of high-entropy alloying is gradually being applied by researchers in the design and development of new alloys.

[0015] Based on the applicant's preliminary work, in high-entropy high-temperature alloy systems, elements can be classified into Ni-like (including Ni, Fe, and Co), Cr-like (including Cr, Mo, and W), and Al-like (including Al, Ti, Nb, and Ta) according to their inter-element interactions. For simplicity, the three clustered elements will be described as follows: in, The element has a negative mixing enthalpy with the matrix element, strong interaction, and preferentially occupies the central atomic site; Elements will preferentially occupy cluster positions, forming Clusters, with excess content entering connecting atomic sites; relatively positive enthalpy of mixing with matrix elements, and weak interaction. Elements occupy connecting atomic positions. By analyzing numerous deformed high-temperature alloys and high-entropy alloys, the composition formula of novel deformed high-entropy high-temperature alloy clusters can be obtained as follows:

[0016] In novel high-entropy high-temperature alloys Elements primarily form the γ′ coherent strengthening phase, determining not only the γ′ particle content but also its precipitation temperature and rate. This directly impacts the alloy's mechanical properties and its processing and deformation capabilities. Al is the main element forming the γ′ phase, contributing to lower alloy density and forming a protective film on the metal surface at high temperatures, enhancing oxidation and corrosion resistance. Ti, Nb, and Ta stabilize the solid solution temperature and volume fraction of the γ′ phase, improving oxidation and hot corrosion resistance. However, excessive Ti content leads to the formation of the harmful η phase and increases the γ′ phase dissolution temperature, narrowing the hot working window. Excessive Nb content causes severe segregation and the formation of the harmful δ phase. As a heavy element, excessive Ta content significantly affects alloy density and processing and deformation capabilities. The precipitation of harmful phases can seriously affect the high-temperature stability of the γ / γ′ coherent structure. At the same time, in order to ensure the low density and high strength requirements of the alloy, while limiting the content, it is necessary to ensure that the atomic percentage of (Ti+Nb) / Al is 0.8 to 2 in order to prevent the precipitation of harmful phases and ensure the high-temperature structural stability and excellent mechanical properties. These elements play a role in solid solution strengthening, as well as corrosion resistance and oxidation resistance. Furthermore, they can increase the diffusion activation energy of other elements, slowing down the diffusion process and further improving microstructure stability. However, excessive Cr can form the harmful σ phase; W, with its high specific gravity, significantly increases the alloy's density; and excessive Mo can lead to the precipitation of harmful phases such as topologically close-packed phases (TCP) and lower the precipitation temperature of the γ′ phase, resulting in insufficient temperature resistance. Therefore, while limiting the content, it is necessary to ensure that the atomic percentage of Cr / Mo is between 9 and 14.5. Elements can improve matrix stability, while the addition of Co can reduce the matrix stacking fault energy, induce stacking faults and twinning, and significantly improve the alloy's endurance strength and creep resistance. Adding Fe can reduce alloy cost, but excessive addition will reduce alloy strength and creep performance. Furthermore, in alloy system design, achieving a suitable Fe-Cr element ratio is difficult, often resulting in brittle phases due to improper addition. Additionally, to refine grains and improve grain boundary bonding, resulting in a small amount of dispersed carbides at the alloy grain boundaries, trace amounts of C, B, and Zr are required. However, excessive addition of these elements can also affect the alloy's weldability, reduce its plasticity, and impact creep performance. Therefore, by combining cluster design with the principle of high-entropy alloying, the low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy was finally determined to be: Ni-(12~25)Co-(8.5~17.5)Fe-(15.5~17)Cr-(2~3)Mo-(1.5~3)Al-(2~4)Ti-(0~5.7)Nb-(0.01~0.05)C-(0.005~0.02)B-(0.01~0.03)Zr.

[0017] This invention utilizes a densitometer (XS64) to detect the density of the alloy; and employs metallurgical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD, Cu K) to measure the density of the alloy. α The microstructure and structure of the alloy were detected by radiation (λ = 0.15406 nm); the hardness of the alloy was tested at different aging times at 750℃ using an HVS-1000 Vickers hardness tester; and the tensile mechanical properties at room temperature and 750℃ were tested using a UTM5504 electronic universal tensile testing machine. Based on these findings, the present invention is determined to be the aforementioned low-density, high-entropy high-temperature alloy resistant to deformation at 750℃. The alloy composition by mass percentage (wt.%) is as follows: Co: 12–25, Fe: 8.5–17.5, Cr: 15.5–17.0, Mo: 2.0–3.5, Al: 1.5–3, Ti: 2–4, Nb: 0–5.7, C: 0.01–0.05, B: 0.005–0.02, Zr: 0.01–0.03, Ni: balance. The atomic percentage ratio of (Ti+Nb) / Al is 0.8–2, and the atomic percentage ratio of Cr / Mo is 9–14.5. The microstructure and performance indicators are as follows: the total volume percentage of the γ′ phase in the alloy is 30–40%, with a very small amount of carbides dispersed at the grain boundaries. After long-term aging at 750℃, the γ′ particles show no significant coarsening, and the coarsening rate K of the γ′ particles is ≤0.1 nm. 3 It exhibits excellent high-temperature structural stability; density ≤7.9g / cm³. 3Room temperature yield strength > 1100 MPa, tensile strength > 1450 MPa, room temperature elongation > 15%, high temperature yield strength at 750℃ > 950 MPa, hardness HV ≥ 420 kgf·mm before and after long-term aging at 750℃. -2 It exhibits excellent high-temperature structural stability.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) This invention designs and develops a low-density, 750℃-resistant Ni-Co-Fe-Cr-based wrought high-entropy superalloy based on the applicant's independently developed cluster composition method. Compared to existing wrought superalloys and high-entropy alloys, the alloy density of this invention is ≤7.9 g / cm³. 3 This is much smaller than that of representative wrought high-temperature alloys, such as In 718 alloy (8.24 g / cm³). 3 In 718Plus alloy (8.36g / cm³) 3 ) and U720Li alloy (8.14g / cm) 3 Furthermore, the use of multiple principal matrix elements results in a wider composition range and lower alloy design and manufacturing costs.

[0020] (2) The total volume percentage of the γ′ phase in this series of alloys is 30-40%, and it contains a very small amount of carbides dispersed at the grain boundaries. After long-term aging at 750℃, the γ′ particles do not show obvious coarsening, and the coarsening rate of the γ′ particles K≤0.1nm. 3 / s, possessing excellent high-temperature structural stability, mainly due to the retarded diffusion effect of elements after high-entropy alloying, which slows down the coarsening rate of the alloy.

[0021] (3) The series alloys, in the absence of high-temperature-resistant elements such as W and Ta, can achieve a hardness HV≥420kgf·mm before and after long-term aging at 750℃. -2 The series of alloys have a high-temperature yield strength of >950MPa at 750℃. Attached Figure Description

[0022] Figure 1 The engineering stress-strain curves of the alloy prepared in Example 1 at room temperature and 750°C.

[0023] Figure 2 The image shows the SEM microstructure of the alloy prepared in Example 2, with a small amount of carbides dispersed on the grain boundaries of equiaxed grains.

[0024] Figure 3 The image shows the SEM microstructure of the alloy prepared in Example 2, where γ′ nanoparticles are coherently precipitated on the matrix. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in detail below with reference to the technical solution.

[0026] Example 1:

[0027] Ni-12.46Co-8.86Fe-16.77Cr-2.54Mo-2.57Al-4Ti-0.01C-0.005B-0.03Zr (wt.%) alloy

[0028] Step 1: Alloy Preparation

[0029] High-purity raw materials were used. 100g of raw materials were mixed according to the mass percentage and placed in a vacuum electric arc furnace. The raw materials were repeatedly melted five times under an argon atmosphere, with the electromagnetic stirring system activated eight times during the melting process, to obtain a homogeneous alloy ingot. The ingot was then melted in a vacuum electric arc tilting casting furnace and tilted into a rectangular casting plate. The alloy ingot was homogenized in a muffle furnace at 1200℃ for 4 hours, then air-cooled for 1 minute and water-cooled. Subsequently, it underwent multiple cold rolling passes with a total deformation of approximately 80%, yielding a plate sample with a thickness of approximately 2mm. After solution treatment at 1050℃ for 1 hour, it was then aged at 750℃ for 24 hours to obtain the final product.

[0030] Step Two: Testing of Alloy Density, Microstructure, and Mechanical Properties

[0031] The density of the alloy was measured using a hydrometer, and the result was 7.84 g / cm³. 3 The microstructure and structure of the stabilized alloy were examined using OM, SEM, and XRD. The results showed that the alloy grains were equiaxed, with a small amount of carbides dispersed at the grain boundaries. Figure 1 High-density γ′ nanoparticles coherently precipitate on the matrix, and these γ′ particles remain stable for a long period at 750℃. After aging for 500 hours, the γ′ particle size remains essentially unchanged, approximately 35 nm, with a stable volume percentage of approximately 40%. The γ / γ′ coherent structure is stable, with no other harmful phases precipitating. Hardness tests using a Vickers hardness tester show a hardness HV of 489 ± 11 kgf·mm after aging and after aging at 750℃ for 100, 200, and 500 hours, respectively. -2 The basic properties remain unchanged; tensile property data at room temperature and 750℃ were measured using an MTS universal tensile testing machine: room temperature yield strength σ s =1290MPa, tensile strength σ b =1508MPa, elongation after fracture δ =15.5%; high temperature yield strength σ at 750℃ s =1169MPa.

[0032] Example 2:

[0033] Ni-24.18Co-17.19Fe-15.74Cr-2.46Mo-1.66Al-2.95Ti-5.7Nb-0.05C-0.02B-0.01Zr (wt.%) alloy

[0034] Step 1: Alloy Preparation

[0035] High-purity raw materials were used. 100g of raw materials were mixed according to a specific mass percentage and placed in a vacuum electric arc furnace. The raw materials were repeatedly melted four times under an argon atmosphere, with an electromagnetic stirring system activated ten times during the melting process, resulting in a homogeneous alloy ingot. This ingot was then melted in a vacuum electric arc tilting casting furnace and cast into a rectangular plate. The alloy ingot was then homogenized in a muffle furnace at 1250℃ for 2 hours, air-cooled for 3 minutes, and then water-cooled. Subsequently, it underwent multiple cold rolling passes, with a total deformation of approximately 90%, yielding a plate sample with a thickness of approximately 1mm. After solution treatment at 1060℃ for 1 hour, and aging treatment at 740℃ for 28 hours, the final product was obtained.

[0036] Step Two: Testing of Alloy Density, Microstructure, and Mechanical Properties

[0037] The density of the alloy was tested using a hydrometer, and the result was 7.90 g / cm³. 3 The microstructure and structure of the alloy after stabilization treatment were examined using OM, SEM, and XRD. The results showed that the alloy grains were equiaxed, with a small amount of carbides dispersed at the grain boundaries. High-density γ′ nanoparticles were coherently precipitated in the matrix, similar to Example 1. Furthermore, the γ′ particles remained stable for a long period at 750℃. After aging for 500 hours, the γ′ particle size remained essentially unchanged, γ′ ~ 40 nm, and the volume percentage remained stable at ~ 37%. The γ / γ′ coherent structure was stable, with no other harmful phases precipitating. Hardness tests were performed using a Vickers hardness tester. After aging and after aging at 750℃ for 100 hours, 200 hours, and 500 hours, the hardness HV = 485 ± 18 kgf·mm². -2 The basic properties remain unchanged; tensile property data at room temperature and 750℃ were measured using an MTS universal tensile testing machine: room temperature yield strength σ s =1329MPa, tensile strength σ b =1722MPa, elongation after fracture δ =15.8%; high temperature yield strength σ at 750℃ s =980MPa.

[0038] Example 3:

[0039] Ni-12.23Co-8.69Fe-16.46Cr-2.49Mo-2.52Al-2Ti-3.86Nb-0.02C-0.0015B-0.02Zr (wt.%) alloy

[0040] Step 1: Alloy Preparation

[0041] High-purity raw materials were used. 100g of raw materials were mixed according to the mass percentage and placed in a vacuum electric arc furnace. The raw materials were repeatedly melted five times under an argon atmosphere, with the electromagnetic stirring system activated nine times during the melting process, to obtain a homogeneous alloy ingot. The ingot was then melted in a vacuum electric arc tilting casting furnace and tilted into a rectangular casting plate. The alloy ingot was homogenized in a muffle furnace at 1220℃ for 4 hours, then air-cooled for 5 minutes and water-cooled. Subsequently, it underwent multiple cold rolling passes, with a total deformation of approximately 85%, to obtain a plate sample with a thickness of approximately 1.5mm. After solution treatment at 1060℃ for 1 hour, it was then aged at 760℃ for 20 hours to obtain the final product.

[0042] Step Two: Testing of Alloy Density, Microstructure, and Mechanical Properties

[0043] The density of the alloy was tested using a hydrometer, and the result was 7.90 g / cm³. 3 The microstructure and structure of the alloy after stabilization treatment were examined using OM, SEM, and XRD. The results showed that the alloy grains were equiaxed, with a small amount of carbides dispersed at the grain boundaries. High-density γ′ nanoparticles were coherently precipitated in the matrix, similar to Example 1. Furthermore, the γ′ particles remained stable for a long period at 750℃. After aging for 500 hours, the γ′ particle size remained essentially unchanged, approximately 40 nm, with a stable volume percentage of approximately 35%. The γ / γ′ coherent structure was stable, with no other harmful phases precipitating. Hardness tests were performed using a Vickers hardness tester. After aging and after aging at 750℃ for 100 hours, 200 hours, and 500 hours, the hardness HV was 483 ± 7 kgf·mm. -2 The basic properties remain unchanged; tensile property data at room temperature and 750℃ were measured using an MTS universal tensile testing machine: room temperature yield strength σ s =1291MPa, tensile strength σ b =1520MPa, elongation after fracture δ =16.5%; high temperature yield strength σ at 750℃ s =982MPa.

[0044] Example 4:

[0045] Ni-12.28Co-11.64Fe-17Cr-3.5Mo-3Al-1.65Ti-1.94Nb-0.02C-0.015B-0.03Zr (wt.%) alloy

[0046] Step 1: Alloy Preparation

[0047] High-purity raw materials were used. 100g of raw materials were mixed according to the mass percentage and placed in a vacuum electric arc furnace. The raw materials were repeatedly melted four times under an argon atmosphere, with the electromagnetic stirring system activated eight times during the melting process, to obtain a homogeneous alloy ingot. The ingot was then melted in a vacuum electric arc tilting casting furnace and tilted into a rectangular casting plate. The alloy ingot was homogenized in a muffle furnace at 1200℃ for 4 hours, then air-cooled for 1 minute and water-cooled. Subsequently, it underwent multiple cold rolling passes with a total deformation of approximately 85%, yielding a plate sample with a thickness of approximately 1.5mm. After solution treatment at 1050℃ for 0.5 hours, it was aged at 750℃ for 24 hours to obtain the final product.

[0048] Step Two: Testing of Alloy Density, Microstructure, and Mechanical Properties

[0049] The density of the alloy was measured using a hydrometer, and the result was 7.89 g / cm³. 3 The microstructure and structure of the alloy after stabilization treatment were examined using OM, SEM, and XRD. The results showed that the alloy grains were equiaxed, with a small amount of carbides dispersed at the grain boundaries. High-density γ′ nanoparticles were coherently precipitated in the matrix, similar to Example 1. Furthermore, the γ′ particles remained stable for a long period at 750℃. After aging for 500 hours, the γ′ particle size remained essentially unchanged, approximately 50 nm, with a stable volume percentage of approximately 38%. The γ / γ′ coherent structure was stable, with no other harmful phases precipitating. Hardness tests were performed using a Vickers hardness tester. After aging and at 750℃ for 100 hours, 200 hours, and 500 hours, the hardness HV was 428 ± 7 kgf·mm. -2 The basic properties remain unchanged; tensile property data at room temperature and 750℃ were measured using an MTS universal tensile testing machine: room temperature yield strength σ s =1180MPa, tensile strength σ b =1500MPa, elongation after fracture δ=18.5%; high temperature yield strength σ at 750℃ s =952MPa.

[0050] Example 5:

[0051] Ni-15.17Co-10.35Fe-15.53Cr-2Mo-2.78Al-3.94Ti-1.91Nb-0.04C-0.02B-0.01Zr (wt.%) alloy

[0052] Step 1: Alloy Preparation

[0053] High-purity raw materials were used. 100g of raw materials were mixed according to the mass percentage and placed in a vacuum electric arc furnace. The raw materials were repeatedly melted four times under an argon atmosphere, with the electromagnetic stirring system activated six times during the melting process, to obtain a homogeneous alloy ingot. The ingot was then melted in a vacuum electric arc tilting casting furnace and tilted into a rectangular casting plate. The alloy ingot was homogenized in a muffle furnace at 1200℃ for 4 hours, then air-cooled for 3 minutes and water-cooled. Subsequently, it underwent multiple cold rolling passes, with a total deformation of approximately 85%, to obtain a plate sample with a thickness of approximately 1.5mm. After solution treatment at 1070℃ for 0.5 hours, it was aged at 740℃ for 28 hours to obtain the final product.

[0054] Step Two: Testing of Alloy Density, Microstructure, and Mechanical Properties

[0055] The density of the alloy was measured using a hydrometer, and the result was 7.78 g / cm³. 3 The microstructure and structure of the alloy after stabilization treatment were examined using OM, SEM, and XRD. The results showed that the alloy grains were equiaxed, with a small amount of carbides dispersed at the grain boundaries. High-density γ′ nanoparticles were coherently precipitated in the matrix, similar to Example 1. Furthermore, the γ′ particles remained stable for a long period at 750℃. After aging for 500 hours, the γ′ particle size remained essentially unchanged, approximately 55 nm, with a stable volume percentage of approximately 40%. The γ / γ′ coherent structure was stable, with no other harmful phases precipitating. Hardness tests were performed using a Vickers hardness tester. After aging and at 750℃ for 100 hours, 200 hours, and 500 hours, the hardness HV was 458 ± 7 kgf·mm. -2 The basic properties remain unchanged; tensile property data at room temperature and 750℃ were measured using an MTS universal tensile testing machine: room temperature yield strength σ s =1310MPa, tensile strength σ b =1585MPa, elongation after fracture δ=17.5%; high temperature yield strength σ at 750℃ s =1120MPa.

[0056] 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 low-density, Ni-Co-Fe-Cr based deformation high-entropy superalloy with a temperature resistance of 750℃, characterized in that, The low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy comprises Ni, Co, Fe, Cr, Mo, Al, Ti, Nb, C, B, and Zr elements, with the following mass percentages (wt.%): Co: 12~25, Fe: 8.5~17.5, Cr: 15.5~17.0, Mo: 2.0~3.5, Al: 1.5~3, Ti: 2~4, Nb: 0~5.7, C: 0.01~0.05, B: 0.005~0.02, Zr: 0.01~0.03, Ni: balance, and the atomic percentage ratio of (Ti+Nb) / Al is 0.8~2, and the atomic percentage ratio of Cr / Mo is 9~14.

5. In the alloy, γ′ particles are coherently precipitated on the FCC-γ matrix, with a total volume percentage of γ′ phase of 30~40%. %, and contains a very small amount of carbides dispersed at the grain boundaries. After long-term aging at 750 °C, the γ′ particles showed no significant coarsening, and the coarsening rate of the γ′ particles was [missing information]. K ≤0.1 nm 3 / s; The typical properties of the alloy are: density ≤ 7.9 g / cm³. 3 Room temperature yield strength >1100MPa, tensile strength >1450MPa, room temperature elongation >15%, high temperature yield strength at 750℃ >950MPa, hardness before and after long-term aging at 750℃ HV ≥ 420 kgf·mm -2 It exhibits excellent high-temperature structural stability.

2. A method for preparing the low-density, 750℃-resistant Ni-Co-Fe-Cr-based deformable high-entropy superalloy as described in claim 1, characterized in that, Includes the following steps, Step 1: Weigh the high-purity alloy material according to the mass percentage, and add it to the vacuum arc melting furnace according to the principle of lower melting point at the bottom and higher melting point at the top. Melt it repeatedly at least several times, and turn on the electromagnetic stirring system 8 to 10 times during the process without opening the furnace door in the middle to ensure that the alloy ingot composition is uniform. Step 2: Melt it using a vacuum electric arc tilting casting furnace and then tilt it to cast a rectangular plate; Step 3: The alloy ingot is homogenized using a muffle furnace, then air-cooled and water-cooled to room temperature; subsequently, it undergoes multiple passes of unidirectional cold rolling, with a single reduction of 0.1~0.5 mm and a total reduction of 80~90%, to obtain a cold-rolled sheet of 1~2 mm thickness; finally, after solution treatment and water cooling, it undergoes aging water cooling at 740~760℃ for 20~28 h to obtain the final product; In step three, the homogenization treatment is carried out at a temperature of 1200~1250 ℃ for 2~4 h; the solution treatment is carried out at a temperature of 1050~1070 ℃ for 0.5~1 h.

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