FeCrNiMnMoCu high-entropy alloy, and preparation method and application thereof

Abstract

The application provides a FeCrNiMnMoCu high-entropy alloy and a preparation method and application thereof, and relates to the technical field of alloy preparation. According to atomic percentage, the high-entropy alloy comprises the following elements: Fe 20-35%, Cr 20-35%, Ni 20-35%, Mn 5-20%, Mo 2.5-8.5% and Cu 1-2.5%, wherein the atomic number ratio of Mo to Cu is 1-4:1. In the system composed of Fe, Cr, Ni and Mn, Mo and Cu are introduced, the ratio of Fe, Cr, Ni, Mn, Mo and Cu is optimized, a solid solution matrix mainly in a face-centered cubic (FCC) structure is formed, and the synergistic effect of high content Cr, Ni elements and the introduced Mo element significantly enhances the stability of the passivation film and the corrosion resistance of the high-entropy alloy in harsh environments.

Description

Technical Field

[0001] This invention relates to the field of alloy manufacturing technology, and in particular to a FeCrNiMnMoCu high-entropy alloy, its preparation method, and its application. Background Technology

[0002] Dry vacuum pumps, with their outstanding advantages such as oil-free operation, high pumping efficiency, and simple maintenance, have become core equipment in high-end industries such as semiconductor manufacturing, precision chemicals, biopharmaceuticals, and aerospace. In these applications, the process environment often contains highly corrosive media, such as CF4, NF3, ClF3, HCl, and HBr generated during semiconductor etching and cleaning processes, as well as byproducts like NH4F. These corrosive substances are drawn into the pump chamber along with the process gas flow. Simultaneously, during vacuum pump operation, the rotor and gas generate a large amount of heat due to high-speed friction and compression, causing the local temperature within the pump chamber to frequently exceed 200°C. This harsh operating condition, combining high temperature and corrosion, rapidly accelerates the corrosion and surface degradation of internal pump components, leading to premature component failure and seriously threatening the long-term operational stability and process reliability of the equipment.

[0003] Currently, core components of dry vacuum pumps (such as rotors and stators) are generally made of ductile iron. This material has good casting properties, machinability, high strength and toughness, and is relatively inexpensive. However, ductile iron has severely insufficient corrosion resistance under the combined effects of high-temperature corrosive atmospheres and thermal cycling loads. Its surface is prone to pitting corrosion, uniform corrosion, and even stress corrosion cracking, which has become a major bottleneck restricting the service life and reliability of dry vacuum pumps in harsh environments.

[0004] High-entropy alloys, as a novel multi-element alloy system, exhibit superior mechanical properties, corrosion resistance, and thermal stability compared to traditional alloys due to their unique high-entropy effect, lattice distortion effect, and slow diffusion effect, making them an ideal substitute for ductile iron. Adding Mo to FeCrNiMn high-entropy alloys can improve corrosion resistance to some extent. However, the addition of Mo easily induces severe dendritic segregation and promotes the precipitation of Cr- and Mo-rich σ phases. Studies have shown that when the precipitated σ phase is continuously and widely distributed in the matrix, it will reduce the plasticity, toughness and other mechanical properties of the alloy as a brittle phase (e.g., Tirunilai AS, Wolf A, Laplanche G. Effect of TCP phases on tensile properties of engineering alloys: Insights gained from a CrMnFeCoNi high-entropy alloy[J]. Acta Materialia, 2010, 301(000):18; Yao Xiaofei, Wei Jingpeng, Lü Yukun, Li Tianye. (CoCrFeMnNi)97.02Mo2.98. σ phase precipitation evolution and mechanical properties of high-entropy alloy[J]. Acta Metallurgica Sinica, 2020, 56(5):769-775).

[0005] Meanwhile, the significant compositional and electrochemical differences between this continuous and coarse σ phase and the matrix will lead to strong microgalvanic corrosion, making it a weak area where corrosion preferentially occurs, which in turn significantly weakens the overall corrosion resistance of the alloy (e.g., references: Dong Shujun, Zhao Qiancheng, Cheng Hongxu, et al. Research progress on corrosion behavior and mechanism of high-entropy alloys[J]. Science & Technology Review, 2025(17):62-76; Duan J, Jiang Z, Huang F, et al. Mechanistic exploration of the exceptional corrosion resistance of the newly designed FeCoCrNiMoxNbxhigh-entropy alloys[J]. Journal of Materials Science & Technology, 2025, 221(000):204-219.).

[0006] Therefore, there is an urgent need to develop a new type of alloy material and its preparation method that can effectively control the morphology and distribution of the σ phase, avoid its formation of a coarse and continuous microstructure, and improve its durability in high-temperature corrosive environments. Summary of the Invention

[0007] This invention provides a FeCrNiMnMoCu high-entropy alloy, its preparation method, and its application. Through optimized composition design and preparation process, this high-entropy alloy can obtain a refined and dispersed σ-phase structure, thereby maintaining good mechanical properties while exhibiting excellent high-temperature corrosion resistance. This solves the technical problem of insufficient corrosion resistance leading to early corrosion failure of existing ductile iron under harsh working conditions involving multiple factors such as acidic atmosphere, high temperature, thermal cycling, and friction.

[0008] In a first aspect, the present invention provides a FeCrNiMnMoCu high-entropy alloy, wherein the high-entropy alloy comprises the following elements by atomic percentage: Fe 20-35%, Cr 20-35%, Ni 20-35%, Mn 5-20%, Mo 2.5-8.5% and Cu 1-2.5%, the sum of the atomic percentages of each element being 100%, wherein the atomic ratio of Mo to Cu is 1-4:1.

[0009] This invention introduces Mo and Cu into a system composed of Fe, Cr, Ni, and Mn. By optimizing the ratio of Fe, Cr, Ni, Mn, Mo, and Cu, a solid solution matrix with a face-centered cubic (FCC) structure is formed. Fe, as the main matrix element, provides the alloy with excellent plasticity and processing properties. Mn, as a strong austenite stabilizing element, effectively reduces stacking fault energy, helps maintain the stability of the FCC structure, and improves casting fluidity. The synergistic effect of high Cr and Ni content and the introduced Mo significantly enhances the stability and corrosion resistance of the passivation film of the high-entropy alloy in harsh environments. The addition of Cu can, on the one hand, form nanoscale Cu-rich clusters in the matrix, providing favorable sites for the heterogeneous nucleation of the σ phase and promoting its dispersed precipitation. On the other hand, by controlling the atomic percentages of Mo and Cu, the nucleation and growth kinetics of the σ phase can be effectively controlled. Furthermore, controlling the atomic ratio of Mo to Cu within the aforementioned range optimizes the melt structure and elemental segregation behavior during solidification, facilitating the formation of numerous fine, dispersed σ phase nuclei in the later stages of solidification and inhibiting their excessive growth and aggregation. This refines the σ phase in the alloy microstructure, resulting in a refined and dispersed σ phase distribution. These fine σ phase particles can act as precipitation strengthening agents, helping to maintain a good balance between strength and plasticity in the alloy. Simultaneously, their dispersed distribution avoids the formation of continuous galvanic corrosion channels with the matrix, thereby improving the overall corrosion resistance of the high-entropy alloy.

[0010] Preferably, the high-entropy alloy comprises the following elements by atomic percentage: Fe 20-30%, Cr 20-30%, Ni 20-30%, Mn 10-20%, Mo 5-8.5% and Cu 1-2.5%, wherein the atomic ratio of Mo to Cu is 2.5-3.5:1, and the sum of the atomic percentages of each element is 100%.

[0011] When the atomic percentages of each element and the ratio of Mo to Cu atoms are controlled within the above range, the σ phase can be more effectively dispersed and precipitated in the form of fine particles, thereby achieving better high-temperature corrosion resistance while maintaining good strength and plasticity.

[0012] In some optional embodiments of the present invention, the high-entropy alloy comprises the following elements by atomic percentage: Fe 24.1-24.7%, Cr 24.1-24.7%, Ni 24.1-24.7%, Mn 16.9-17.3%, Mo 6.2-8.4% and Cu 2.4-2.5%, wherein the atomic ratio of Mo to Cu is 2.5-3.5:1, and the sum of the atomic percentages of each element is 100%.

[0013] In one optional embodiment of the present invention, the high-entropy alloy comprises the following elements by atomic percentage: Fe 24.4%, Cr 24.4%, Ni 24.4%, Mn 17.1%, Mo 7.3% and Cu 2.4%, wherein the atomic ratio of Mo to Cu is 3:1.

[0014] In one optional embodiment of the present invention, the high-entropy alloy comprises the following elements by atomic percentage: Fe 24.7%, Cr 24.7%, Ni 24.7%, Mn 17.3%, Mo 6.2% and Cu 2.5%, wherein the atomic ratio of Mo to Cu is 2.5:1.

[0015] In one optional embodiment of the present invention, the high-entropy alloy comprises the following elements by atomic percentage: Fe 24.1%, Cr 24.1%, Ni 24.1%, Mn 16.9%, Mo 8.4% and Cu 2.4%, wherein the atomic ratio of Mo to Cu is 3.5:1.

[0016] In some optional embodiments of the present invention, the high-entropy alloy is composed of the following elements: Fe, Cr, Ni, Mn, Mo, and Cu in an atomic ratio of 1:1:1:0.7:0.25-0.35:0.1.

[0017] In one optional embodiment of the present invention, the high-entropy alloy is composed of the following elements: Fe, Cr, Ni, Mn, Mo, and Cu in an atomic ratio of 1:1:1:0.7:0.3:0.1.

[0018] In one optional embodiment of the present invention, the high-entropy alloy is composed of the following elements: Fe, Cr, Ni, Mn, Mo, and Cu in an atomic ratio of 1:1:1:0.7:0.25:0.1.

[0019] In one optional embodiment of the present invention, the high-entropy alloy is composed of the following elements: Fe, Cr, Ni, Mn, Mo, and Cu in an atomic ratio of 1:1:1:0.7:0.35:0.1.

[0020] A second aspect of the present invention provides a method for preparing the FeCrNiMnMoCu high-entropy alloy, comprising the following steps: (1) The metal raw materials containing Fe, Cr, Ni, Mn, Mo and Cu are respectively weighed according to the atomic percentage of the corresponding elements in the high entropy alloy to form a mixed raw material. The mixed raw material is then melted and cooled to obtain an alloy ingot. (2) Anneal the alloy ingot.

[0021] Further, step (1) includes the following steps: S1. Mix the metal raw materials containing Fe, Cr, Ni and Mn with a portion of the metal raw materials containing Mo and then perform a first smelting. After cooling, a first alloy ingot is obtained. S2. Add the remaining Mo-containing metal raw materials and Cu-containing metal raw materials to the primary alloy ingot, perform secondary melting, and obtain a secondary alloy ingot after cooling. S3. The secondary alloy ingot is remelted. The mass ratio of the Mo-containing metal raw material used in the primary smelting to that used in the secondary smelting is 1-2:1.

[0022] In the above technical solution, a portion of the Mo-containing metal raw material is first smelted with the Fe, Cr, Ni, and Mn-containing metal raw materials, and then the remaining Mo-containing metal raw material is smelted with the Cu-containing metal raw material in a second smelting process. Compared with the traditional one-time feeding method, this effectively promotes the uniform distribution and fusion of high-melting-point Mo in the matrix, solving the problems of uneven Mo distribution, unmelted block formation, and segregation in the traditional process, thereby significantly improving the macroscopic and microscopic compositional uniformity of the ingot. The simultaneous addition of Cu during the second smelting process utilizes Cu's regulatory effect on the composition of local micro-regions in the melt, promoting the formation of more fine σ-phase nucleation sites in the Mo-rich areas and inhibiting their excessive growth and connection, forming fine, dispersed σ-phases. These fine σ-phases not only avoid serious damage to the plasticity of the matrix, but more importantly, they have a smaller electrochemical difference with the FCC matrix, and their dispersed distribution breaks the network-like corrosion channels formed by the coarse continuous σ-phases, making corrosion less likely to occur and spread preferentially, thus significantly improving the high-temperature corrosion resistance of the high-entropy alloy.

[0023] Meanwhile, the absence of Cu-containing metal raw materials in the first smelting is to prevent Cu from interacting with Mo too early and too quickly during the initial solidification process, which could lead to the formation of coarse intermetallic compounds or elemental segregation. By delaying the addition of Cu to the second smelting and adding it together with the remaining Mo, the regulatory effect of Cu on the nucleation and growth of the σ phase can be utilized more precisely during the critical stages of remelting and compositional rehomogenization. This allows for more effective control over the size and distribution of the σ phase, contributing to the formation of fine, diffusely distributed σ phases.

[0024] In addition, controlling the mass ratio of Mo-containing metal raw materials used in primary and secondary smelting within the above range is beneficial to reducing the local concentration gradient of Mo during a single smelting process, reducing dendrite segregation, and promoting uniform mixing and diffusion of Mo with elements such as Cu and Cr.

[0025] In the preparation of the high-entropy alloy of the present invention, the stepwise and controlled addition method described above optimizes the melt solidification process, which helps to form more fine and dispersed σ phase nuclei in the subsequent annealing and inhibits their excessive growth. In the end, a microstructure that is beneficial to improving the comprehensive mechanical properties and high-temperature corrosion resistance of the high-entropy alloy is obtained, so that the high-entropy alloy maintains good mechanical properties while also having excellent high-temperature corrosion resistance.

[0026] Furthermore, in step S2, the remaining Mo-containing metal raw materials and Cu-containing metal raw materials are added to the primary alloy ingot in multiple batches for secondary smelting. That is, in step S2, the remaining Mo-containing metal raw materials and Cu-containing metal raw materials are added to the primary alloy ingot in at least two batches for multi-stage smelting. Preferably, step S2 includes: S21. Divide the remaining Mo-containing metal raw material after the first smelting into two parts; S22. Add one portion of the Mo-containing metal raw material and one portion of the Cu-containing metal raw material to the primary alloy ingot, and perform a melting and cooling process. S23. Add another portion of the Mo-containing metal raw material and the remaining Cu-containing metal raw material to the alloy ingot obtained after a first stage of melting and cooling, perform a second stage of melting, and obtain the secondary alloy ingot after cooling. The mass ratio of the Mo-containing metal raw material used in the first stage of smelting to that used in the second stage of smelting is (0.5-2):1, and the mass ratio of the Cu-containing metal raw material used in the first stage of smelting to that used in the second stage of smelting is (0.5-2):1.

[0027] Further research in this invention revealed that during the secondary smelting process, the remaining Mo-containing and Cu-containing metal raw materials after the primary smelting are added in stages. Compared to adding both directly, this method further promotes the melting and diffusion of high-melting-point Mo and Cu elements, significantly reduces macroscopic segregation of Mo and Cu, and effectively suppresses the growth of σ phase nucleation. When combining the primary and secondary smelting processes, the Mo- and Cu-containing metal raw materials are used in the aforementioned specific mass ratio, which further enhances the effect of suppressing the formation of coarse, continuously distributed σ phases and helps to form fine, dispersed σ phases. This significantly improves the mechanical properties and high-temperature corrosion resistance of the prepared high-entropy alloy.

[0028] Furthermore, the mass ratio of the Cu-containing metal raw materials used in the first-stage melting and the second-stage melting is (0.8-1.2):1. When the mass ratio of the Cu-containing metal raw materials used in the first-stage melting and the second-stage melting is controlled within the above range, it can better improve the mechanical properties and high-temperature corrosion resistance of the high-entropy alloy.

[0029] Furthermore, the parameters of the annealing treatment include: heating to 600-750℃ at a heating rate of 5-15℃ / min and holding at that temperature for 3-7 h.

[0030] In the above scheme, when the alloy ingot obtained by the present invention is treated with the specific annealing process, casting stress can be effectively eliminated, element diffusion and homogenization can be promoted, and fine σ phases can be precipitated from the supersaturated solid solution. This process spheroidizes, refines, and uniformly disperses the coarse, continuous σ phases, transforming them from harmful corrosion channels into dispersed, relatively harmless σ phases. This results in a solid solution matrix dominated by a face-centered cubic (FCC) structure, while also successfully obtaining a matrix with a uniform matrix containing dispersed σ phases with diameters within 10 micrometers. This σ phase structure can still form a uniform and stable passivation film under harsh conditions such as corrosive media and high temperatures. Simultaneously, the fine σ phases can act as beneficial strengthening phases rather than becoming corrosion initiation points, synergistically endowing the high-entropy alloy with excellent corrosion resistance.

[0031] Furthermore, the mass percentage content of the corresponding elements in each of the metal raw materials containing Fe, Cr, Ni, Mn, Mo and Cu is higher than 99.9%.

[0032] Preferably, the metal raw materials containing Fe, Cr, Ni and Mn are metal block raw materials, and the metal raw materials containing Mo and Cu are Mo powder and Cu powder, respectively.

[0033] Preferably, the metal block raw materials containing Fe, Cr, Ni and Mn need to be pretreated before use. The pretreatment process includes grinding, cleaning, pickling and drying the metal block raw materials.

[0034] Preferably, the pickling solution used is a hydrochloric acid solution with a mass concentration of 10-30%, the treatment temperature is 40-60℃, and the treatment time is 60-120 s.

[0035] Preferably, the Mo powder and Cu powder are dried before use. The drying parameters include: temperature of 50-100℃, preferably 80℃, and time of 2-6 h, preferably 4 h.

[0036] Furthermore, during the primary and secondary melting processes, the raw materials are kept in a molten state for 2-5 minutes, preferably 3 minutes, after melting before cooling.

[0037] Preferably, both the primary and secondary melting are carried out under vacuum conditions, and the parameters for the primary and secondary melting include a vacuum degree of 5.0 × 10⁻⁶. -3 The melting temperature is below Pa, the melting temperature is 1200-1600℃, and argon gas is introduced as a protective atmosphere; Preferably, the remelting is performed 1-3 times, and the parameters are the same as those of the secondary melting. Controlling the number of remeltings within the above range helps to refine the σ phase and improve the mechanical properties and high-temperature corrosion resistance of the high-entropy alloy.

[0038] In a second aspect, the present invention provides the application of the above-described FeCrNiMnMoCu high-entropy alloy or the FeCrNiMnMoCu high-entropy alloy prepared by the above-described preparation method in the preparation of corrosion-resistant components.

[0039] Preferably, the corrosion-resistant component is a vacuum pump.

[0040] Preferably, the FeCrNiMnMoCu high-entropy alloy is used in the manufacture of key components of vacuum pumps, and more preferably in the manufacture of rotors, stators, end caps, vanes, or pump chamber bushings.

[0041] The effective effects of the FeCrNiMnMoCu high-entropy alloy, its preparation method, and its application provided by this invention include at least the following: (1) In this invention, Mo and Cu are introduced into the system composed of Fe, Cr, Ni and Mn. By optimizing the ratio of Fe, Cr, Ni, Mn, Mo and Cu, a solid solution matrix with face-centered cubic (FCC) structure is formed. At the same time, the synergistic effect of the high content of Cr and Ni elements and the introduced Mo element significantly enhances the stability and corrosion resistance of the passivation film of the high entropy alloy in harsh environments. Combined with its specific preparation process, it can synergistically endow the high entropy alloy with excellent mechanical properties and corrosion resistance. (2) The key components of the dry vacuum pump made with the alloy of the present invention have a significantly improved corrosion resistance life compared with traditional ductile iron components in a corrosive environment simulating actual working conditions. At the same time, it avoids the risk of surface coating peeling, providing an ideal material solution for the long-term reliable operation of high-end dry vacuum pumps. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a process flow diagram for preparing FeCrNiMnMoCu high-entropy alloy according to the present invention.

[0044] Figure 2 These are metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Example 1, Comparative Example 1-1, and Comparative Example 1-2.

[0045] Figure 3 These are metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 2-1, 2-2, 2-1, and 2-2.

[0046] Figure 4 These are metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 3-1, 3-2, 3-1, 3-2, 3-3, and 3-4.

[0047] Figure 5 The images show the metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 4-1, 4-2, 4-3, 4-4, Comparative Examples 4-1, 4-2, and 4-3.

[0048] Figure 6 These are metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 5-1, 5-2, 5-1, and 5-2. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0051] Raw material information: Fe-containing metal blocks: purity higher than 99.9 wt.%; Cr-containing metal blocks: purity higher than 99.9 wt.%; Ni-containing metal blocks: purity higher than 99.9 wt.%; Mn-containing metal blocks: purity higher than 99.9 wt.%; Mo-containing metal powder: purity higher than 99.9 wt.%; Cu-containing metal powder: purity higher than 99.9 wt.%.

[0052] The pretreatment methods for the above metal blocks are as follows: The surface of each metal block is sanded to remove oxide scale, then ultrasonically cleaned for 15 minutes each in acetone and anhydrous ethanol to remove oil stains. After cleaning, the metal blocks are immersed in a 20% hydrochloric acid solution and acid-washed at 50°C for 90 seconds to thoroughly remove surface oxides. After acid washing, they are rinsed with deionized water, then rinsed with anhydrous ethanol, and finally dried in a cold air drying oven at 28°C for 20 minutes to obtain Fe-containing, Cr-containing, Ni-containing, and Mn-containing metal blocks, respectively.

[0053] Pretreatment method for Mo-containing metal powder and Cu-containing metal powder: Mo-containing metal powder and Cu-containing metal powder are placed in a vacuum drying oven at 80℃ and dried for 4 hours to obtain Mo powder and Cu powder respectively.

[0054] Example 1 This embodiment provides a method for preparing a FeCrNiMnMoCu high-entropy alloy, the process flow diagram of which is shown below. Figure 1 As shown, the preparation method includes the following steps: (1) Weigh out Fe-containing metal blocks, Cr-containing metal blocks, Ni-containing metal blocks, Mn-containing metal blocks, Mo powder and Cu powder according to the atomic ratio of Fe, Cr, Ni, Mn, Mo and Cu as 1:1:1:0.7:0.3:0.1, and mix them together; (2) Place the Fe-containing metal blocks, Cr-containing metal blocks, Ni-containing metal blocks, Mn-containing metal blocks, and some Mo powder into a water-cooled copper crucible in a vacuum arc melting furnace, and evacuate the furnace to 5.0 × 10⁻⁶. -3 The pressure is below 0.05 MPa, and then high-purity argon gas is introduced to 0.05 MPa; an arc is started for one melting. After the raw material is completely melted, it is kept in a molten state and stirred electromagnetically for 3 minutes. Then the melting is stopped and cooled to obtain a primary alloy ingot. (3) After flipping the first alloy ingot, the remaining Mo powder after the first melting is divided into two parts; one part of the Mo powder and some Cu powder are added to the first alloy ingot, and an arc is started for a first melting. After the raw materials are completely melted, the molten state is maintained and electromagnetic stirring is used for 3 minutes. Then the melting is stopped and the ingot is cooled. Then the other part of the Mo powder and the remaining Cu powder are added to the alloy ingot after the first melting and cooling and flipping. An arc is started for a second melting. After the raw materials are completely melted, the molten state is maintained and electromagnetic stirring is used for 3 minutes. Then the melting is stopped and the ingot is cooled. The operation steps of the second melting are completed, and a second alloy ingot is obtained. The mass ratio of Mo powder used in the first melting, the first stage melting, and the second stage melting is 2.5:1.5:1, and the mass ratio of Cu powder used in the first stage melting and the second stage melting is 1:1. (4) The secondary alloy ingot is subjected to first remelting, second remelting and third remelting (remelting is also a smelting process of the ingot). The ingot is turned over before each remelting and kept in a molten state for 3 minutes each time. The total number of remelting is 3 times, and the total number of smelting and remelting is 6 times, to obtain an alloy ingot with uniform composition; (5) The alloy ingot obtained after remelting in step (4) is sealed in a vacuum quartz tube for annealing. It is heated to 700°C at a heating rate of 10°C / min and held at this temperature for 5 hours. After the holding period, it is cooled to room temperature to obtain FeCrNiMnMoCu high-entropy alloy.

[0055] In this embodiment, the parameters for the primary melting, first-stage melting, second-stage melting, and remelting are: vacuum degree not exceeding 5.0 × 10⁻⁶. -3 Pa, argon protection pressure is 0.05 MPa, melting temperature is 1500℃, and the molten state holding time is 3 min.

[0056] Comparative Example 1-1 The difference between this comparative example and Example 1 is that all the raw materials used to prepare the FeCrNiMnMoCu high-entropy alloy were placed in a vacuum arc melting furnace for melting treatment. The specific steps are as follows: (1) Weigh out Fe-containing metal blocks, Cr-containing metal blocks, Ni-containing metal blocks, Mn-containing metal blocks, Mo powder and Cu powder according to the atomic ratio of Fe, Cr, Ni, Mn, Mo and Cu as 1:1:1:0.7:0.3:0.1, and mix them together; (2) Place all the metal raw materials (metal blocks, Mo powder and Cu powder) weighed in step (1) into the water-cooled copper crucible of the vacuum arc melting furnace, and evacuate the furnace to 5.0 × 10⁻⁶. -3 The pressure is below Pa, then high-purity argon is introduced to 0.05 MPa, the melting temperature is controlled at 1500℃, the arc is started for one melting, after the raw material is completely melted, the molten state is maintained and electromagnetic stirring is used for 3 minutes, then the melting is stopped, and after cooling, a primary alloy ingot is obtained. (3) The alloy ingot is flipped over and then processed in the same way as step (4) of Example 1 to obtain the alloy ingot; (4) The alloy ingot obtained after remelting in step (3) is subjected to the same treatment as step (5) in Example 1 to obtain FeCrNiMnMoCu high-entropy alloy.

[0057] Comparative Examples 1-2 The difference between this comparative example and Example 1 is that all the Cu powder is added in step (2), and the remaining Mo powder after the first melting in step (3) is added all at once for a second melting. The specific steps are as follows: (1) Weigh out Fe-containing metal blocks, Cr-containing metal blocks, Ni-containing metal blocks, Mn-containing metal blocks, Mo powder and Cu powder according to the atomic ratio of Fe, Cr, Ni, Mn, Mo and Cu as 1:1:1:0.7:0.3:0.1, and mix them together; (2) Place the weighed Fe, Cr, Ni, Mn metal blocks, all the Cu powder, and a portion of the Mo powder (accounting for 50% of the total Mo powder mass) into a water-cooled copper crucible in a vacuum arc melting furnace, and evacuate the furnace to 5.0 × 10⁻⁶. -3 The pressure is below Pa, then high-purity argon is introduced to 0.05 MPa, the melting temperature is controlled at 1500℃, the arc is started for one melting, after the raw material is completely melted, the molten state is maintained and electromagnetic stirring is used for 3 minutes, then the melting is stopped, and after cooling, a primary alloy ingot is obtained. (3) After flipping the primary alloy ingot, add all the remaining Mo powder. Under the same vacuum and protective atmosphere, control the molten pool temperature at 1500℃ and start the arc for secondary melting. After the raw materials are completely melted, maintain the molten state and use electromagnetic stirring for 3 minutes, then stop melting and cool to obtain the secondary alloy ingot; (4) The secondary alloy ingot is subjected to the same treatment as step (4) in Example 1 to obtain the alloy ingot; (5) The alloy ingot obtained after remelting in step (4) is subjected to the same treatment as step (5) in Example 1 to obtain FeCrNiMnMoCu high-entropy alloy.

[0058] Metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Example 1, Comparative Example 1-1, and Comparative Example 1-2 are shown below. Figure 2 As shown. Figure 2 (a) is Example 1, (b) is Comparative Example 1-1, and (c) is Comparative Example 1-2.

[0059] Example 2 The preparation methods of Examples 2-1, 2-2 and Comparative Examples 2-1, 2-2 are basically the same as those of Example 1, except that the atomic ratio of each element is different during the ingredient preparation, as detailed below: Example 2-1: The atomic ratio of Fe, Cr, Ni, Mn, Mo and Cu is 1:1:1:0.7:0.25:0.1.

[0060] Example 2-2: The atomic ratio of Fe, Cr, Ni, Mn, Mo and Cu is 1:1:1:0.7:0.35:0.1.

[0061] Comparative Example 2-1: The ratio of the number of Fe, Cr, Ni, Mn, Mo, and Cu atoms is 1:1:1:1:0.1:0.25.

[0062] Comparative Example 2-2: The ratio of the number of Fe, Cr, Ni, Mn, Mo, and Cu atoms is 1:1:1:1:0.4:0.08.

[0063] Metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 2-1, 2-2, 2-1, and 2-2 are shown below. Figure 3 As shown. Figure 3 (a) is Example 2-1, (b) is Example 2-2, (c) is Comparative Example 2-1, and (d) is Comparative Example 2-2.

[0064] Example 3 The preparation methods of Examples 3-1, 3-2 and Comparative Examples 3-1, 3-2 are basically the same as those of Example 1, except that the mass ratio of Mo powder used in the first melting, the first stage melting, and the second stage melting are different, as detailed below: Example 3-1: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 3.75:1.5:1, wherein the ratio of first melting to second melting is 1.5:1.

[0065] Example 3-2: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 5:1.5:1, wherein the ratio of first melting to second melting is 2:1.

[0066] Comparative Example 3-1: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 6:1.5:1, wherein the ratio of first melting to second melting is 2.4:1.

[0067] Comparative Example 3-2: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 1:1.5:1, wherein the ratio of first melting to second melting is 1:2.5.

[0068] Comparative Example 3-3: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 2.5:2:0.5, wherein the ratio of first melting to second melting is 1:1, and the ratio of first stage melting to second stage melting is 4:1.

[0069] Comparative Examples 3-4: The mass ratio of Mo powder used in the first melting, first stage melting and second stage melting is 2.5:0.5:2, wherein the ratio of first melting to second melting is 1:1, and the ratio of first stage melting to second stage melting is 0.025:1.

[0070] The metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 3-1, 3-2, 3-1, 3-2, 3-3, and 3-4 are shown below. Figure 4 As shown. Figure 4(a) is Example 3-1, (b) is Example 3-2, (c) is Comparative Example 3-1, (d) is Comparative Example 3-2, (e) is Comparative Example 3-3, and (f) is Comparative Example 3-4.

[0071] Example 4 The preparation methods of Examples 4-1, 4-2, 4-3, 4-4 and Comparative Examples 4-1, 4-2, 4-3 are basically the same as those of Example 1, except that the annealing temperature and heating rate are different, as detailed below: Example 4-1: Annealing temperature is 750℃.

[0072] Example 4-2: Annealing temperature is 600℃.

[0073] Example 4-3: The heating rate is 5 °C / min.

[0074] Example 4-4: The heating rate is 15 °C / min.

[0075] Comparative Example 4-1: Annealing temperature is 500℃.

[0076] Comparative Example 4-2: Annealing temperature was 900℃.

[0077] Comparative Example 4-3: The heating rate was 20℃ / min.

[0078] The metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 4-1, 4-2, 4-3, 4-4, Comparative Examples 4-1, 4-2, and 4-3 are shown below. Figure 5 As shown. Figure 5 (a) is Example 4-1, (b) is Example 4-2, (c) is Example 4-3, (d) is Example 4-4, (e) is Comparative Example 4-1, (f) is Comparative Example 4-2, and (g) is Comparative Example 4-3.

[0079] Example 5 The preparation methods of Examples 5-1, 5-2 and Comparative Examples 5-1, 5-2 are basically the same as those of Example 1, except that the mass ratio of Cu powder used in the first-stage melting and the second-stage melting is different, as detailed below: Example 5-1: The mass ratio of Cu powder used in the first stage of melting and the second stage of melting is 0.5:1.

[0080] Example 5-2: The mass ratio of Cu powder used in the first stage of melting and the second stage of melting is 2:1.

[0081] Comparative Example 5-1: The mass ratio of Cu powder used in the first stage of melting and the second stage of melting is 0.4:1.

[0082] Comparative Example 5-2: The mass ratio of Cu powder used in the first stage of melting and the second stage of melting is 2.5:1.

[0083] Metallographic images of the FeCrNiMnMoCu high-entropy alloys obtained in Examples 5-1, 5-2, Comparative Examples 5-1 and 5-2 are shown below. Figure 6 As shown. Figure 6 (a) is Example 5-1, (b) is Example 5-2, (c) is Comparative Example 5-1, and (d) is Comparative Example 5-2.

[0084] Test Example 1 Test conditions: The electrolyte used for the potentiodynamic polarization test was 0.05M HCl and 0.05M HF solution. The reference electrode was Ag / AgCl (unless otherwise specified, all potentials are relative to this reference electrode). The counter electrode was a platinum mesh. The working electrode was a cast FeCrNiMnMoCu high-entropy alloy from the examples and comparative examples. The test area was 1 cm². 2 The test temperature was 80℃. The scanning potential range was -0.3 V (vs. OCP) to 1 V (vs. Ag / AgCl), and the scan rate was 25 mV / s. The obtained polarization curves were analyzed using the Tafel extrapolation method to calculate the corrosion current density (Icorr) of the sample.

[0085] The test results are shown in Table 1: As shown in Table 1, the corrosion resistance of the FeCrNiMnMoCu high-entropy alloy prepared in the examples is significantly better than that of the comparative examples. The FeCrNiMnMoCu high-entropy alloy of the present invention has a refined and dispersed σ phase structure, thus exhibiting excellent corrosion resistance while maintaining good mechanical properties.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A FeCrNiMnMoCu high-entropy alloy, characterized in that, The high-entropy alloy comprises the following elements by atomic percentage: Fe 20-35%, Cr 20-35%, Ni 20-35%, Mn 5-20%, Mo 2.5-8.5% and Cu 1-2.5%, wherein the atomic ratio of Mo to Cu is 1-4:

1.

2. The FeCrNiMnMoCu high-entropy alloy according to claim 1, characterized in that, The high-entropy alloy comprises the following elements by atomic percentage: Fe 20-30%, Cr 20-30%, Ni 20-30%, Mn 10-20%, Mo 5-8.5% and Cu 1-2.5%, wherein the atomic ratio of Mo to Cu is 2.5-3.5:

1.

3. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to claim 1 or 2, characterized in that, Includes the following steps: (1) The metal raw materials containing Fe, Cr, Ni, Mn, Mo and Cu are respectively weighed according to the atomic percentage of the corresponding elements in the high entropy alloy to form a mixed raw material. The mixed raw material is then melted and cooled to obtain an alloy ingot. (2) Anneal the alloy ingot.

4. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to claim 3, characterized in that, Step (1) includes the following steps: S1. Mix the metal raw materials containing Fe, Cr, Ni and Mn with a portion of the metal raw materials containing Mo and then perform a first smelting. After cooling, a first alloy ingot is obtained. S2. Add the remaining Mo-containing metal raw materials and Cu-containing metal raw materials to the primary alloy ingot, perform secondary melting, and obtain a secondary alloy ingot after cooling. S3. The secondary alloy ingot is remelted. The mass ratio of the Mo-containing metal raw material used in the primary smelting to that used in the secondary smelting is 1-2:

1.

5. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to claim 4, characterized in that, In step S2, the remaining Mo-containing metal raw materials and Cu-containing metal raw materials are added to the primary alloy ingot in at least two additions for multi-stage smelting. Preferably, step S2 includes: S21. Divide the remaining Mo-containing metal raw material after the first smelting into two parts; S22. Add one portion of the Mo-containing metal raw material and one portion of the Cu-containing metal raw material to the primary alloy ingot, and perform a melting and cooling process. S23. Add another portion of the Mo-containing metal raw material and the remaining Cu-containing metal raw material to the alloy ingot obtained after a first stage of melting and cooling, perform a second stage of melting, and obtain the secondary alloy ingot after cooling. The mass ratio of the Mo-containing metal raw material used in the first stage of smelting to that used in the second stage of smelting is (0.5-2):1, and the mass ratio of the Cu-containing metal raw material used in the first stage of smelting to that used in the second stage of smelting is (0.5-2):

1.

6. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to claim 5, characterized in that, The mass ratio of the Cu-containing metal raw materials used in the first-stage smelting and the second-stage smelting is (0.8-1.2):

1.

7. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to any one of claims 3-6, characterized in that, The parameters for the annealing process include: heating to 600-750℃ at a heating rate of 5-15℃ / min and holding at that temperature for 3-7 hours.

8. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to any one of claims 3-7, characterized in that, The mass percentage of each of the metal raw materials containing Fe, Cr, Ni, Mn, Mo and Cu is higher than 99.9%.

9. The method for preparing the FeCrNiMnMoCu high-entropy alloy according to any one of claims 4-6, characterized in that, During the primary and secondary smelting processes, the raw materials are kept in a molten state for 2-5 minutes after melting before cooling. Preferably, both the primary and secondary melting are carried out under vacuum conditions, and the parameters for the primary and secondary melting include: a vacuum degree of 5.0 × 10⁻⁶. -3 The melting temperature is below Pa, the melting temperature is 1200-1600℃, and argon gas is introduced as a protective atmosphere; Preferably, the remelting is performed 1-3 times, and its parameters are the same as those of the secondary melting.

10. The application of the FeCrNiMnMoCu high-entropy alloy according to claim 1 or 2, or the FeCrNiMnMoCu high-entropy alloy prepared by the preparation method according to any one of claims 3-9, in the preparation of corrosion-resistant components; Preferably, the corrosion-resistant component is a vacuum pump.

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