Fe-Ni-Al-Ti series high-entropy alloy and preparation method thereof

Abstract

The invention provides a Fe-Ni-Al-Ti series high-entropy alloy and a preparation method thereof, and belongs to the technical field of high-entropy alloy materials. The Fe-Ni-Al-Ti series high-entropy alloy comprises, by atomic percent, 0%-40% of cobalt, 20%-50% of nickel, 3%-10% of aluminum, 3%-10% of titanium and the balance iron and inevitable impurities, and the cobalt content is not zero. The preparation method comprises the following steps: weighing raw materials according to the atomic percent, smelting and carrying out suction casting to obtain a cast plate, and then sequentially carrying out homogenization treatment, cold rolling treatment, crystallization annealing treatment and aging treatment to obtain the Fe-Ni-Al-Ti series high-entropy alloy. According to the Fe-Ni-Al-Ti-based high-entropy alloy and the preparation method thereof, by regulating and controlling the Co content, collaborative stabilization, moderate coarsening and optimized distribution of L12 and L21 precipitated phases are successfully achieved in the Fe-Ni-Al-Ti-based high-entropy alloy, and therefore the excellent strength, the excellent plasticity and the remarkably-improved corrosion resistance are synchronously obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-entropy alloy materials, and particularly relates to a Fe-Ni-Al-Ti system high-entropy alloy and a preparation method thereof. BACKGROUND

[0002] High-entropy alloys break the limitation of traditional alloys based on single elements. The high-entropy alloy significantly improves the mixed configuration entropy of the system through its multi-main element chemical composition, thereby effectively inhibiting the enthalpy change driving force required for the formation of intermetallic compounds, and ultimately promoting the stable existence of solid solution phases. At the same time, its slow diffusion effect helps to maintain the stability of the structure and performance, and serious lattice distortion can effectively hinder dislocation movement and thus improve mechanical properties. The cocktail effect enables us to design materials for different application requirements based on the characteristics of the components. Under the combined action of these effects, high-entropy alloys often exhibit unique structural characteristics and performance advantages. The high configuration entropy effect can inhibit the formation of brittle intermetallic compounds and promote the formation of simple solid solution structures. Research shows that by precisely controlling the size, distribution and volume fraction of L12, L21, B2 and other nano precipitates, the strength and plasticity can be synergistically improved.

[0003] In the rapid development process of modern industry and technology, material science, as the cornerstone supporting the technological progress of various industries, is becoming increasingly important. Especially in extreme working conditions, such as chemical production, marine engineering, aerospace, mechanical manufacturing and other fields, equipment and components are faced with multiple severe challenges such as extreme temperature and pressure, strong corrosive medium erosion, long-term mechanical load, etc. This requires materials not only to have excellent tensile mechanical properties (such as high strength, good plasticity) to resist deformation and fracture, but also to have excellent corrosion resistance to cope with environmental erosion. However, when dealing with such complex environments, the microstructure characteristics of traditional materials often cannot support the synergistic optimization of performance: on the one hand, the lack of stability of the microstructure may lead to significant attenuation of the tensile properties (such as yield strength, elongation) during service; on the other hand, the weak links in the microstructure (such as specific phases, grain boundaries, defects) are prone to become the preferred path for corrosion initiation and propagation, accelerating material failure. This limitation in performance not only severely restricts the service life and operational reliability of key equipment and infrastructure, but also deeply affects production efficiency and safety. Therefore, it is of urgent and important significance to develop new materials with high strength and toughness and high corrosion resistance based on the understanding of the internal relationship between the microstructure of materials and their tensile properties and corrosion properties, in order to break through the technical bottleneck and promote industrial upgrading. SUMMARY

[0004] To solve the above technical problems, the application provides a Fe-Ni-Al-Ti high-entropy alloy and a preparation method thereof.

[0005] To achieve the above object, the application provides the following technical scheme.

[0006] One of the technical schemes of the application is as follows:

[0007] A Fe-Ni-Al-Ti high-entropy alloy contains 0-40% of cobalt (Co) in terms of atomic percentage, and the content of cobalt is not 0, and further contains 20-50% of nickel (Ni), 3-10% of aluminum (Al) and 3-10% of titanium (Ti), and the balance is iron (Fe) and inevitable impurities.

[0008] Preferably, the Fe-Ni-Al-Ti high-entropy alloy contains 11-30% of cobalt, 28-38% of nickel, 7% of aluminum and 7% of titanium in terms of atomic percentage, and the balance is iron and inevitable impurities.

[0009] Preferably, the Fe-Ni-Al-Ti high-entropy alloy contains 11% of cobalt, 37.5% of nickel, 7% of aluminum and 7% of titanium in terms of atomic percentage, and the balance is iron and inevitable impurities.

[0010] Preferably, the Fe-Ni-Al-Ti high-entropy alloy contains 20.4% of cobalt, 32.8% of nickel, 7% of aluminum and 7% of titanium in terms of atomic percentage, and the balance is iron and inevitable impurities.

[0011] Preferably, the Fe-Ni-Al-Ti high-entropy alloy contains 28.6% of cobalt, 28.7% of nickel, 7% of aluminum and 7% of titanium in terms of atomic percentage, and the balance is iron and inevitable impurities.

[0012] The second technical scheme of the application is as follows:

[0013] A preparation method of the above Fe-Ni-Al-Ti high-entropy alloy comprises the following steps:

[0014] The raw materials are weighed according to atomic percentage, mixed uniformly, melted and suction cast to obtain a Fe-Ni-Al-Ti high-entropy alloy cast plate.

[0015] The Fe-Ni-Al-Ti high-entropy alloy cast plate is sequentially subjected to homogenization treatment, cold rolling treatment, crystallization annealing treatment and aging treatment to obtain the Fe-Ni-Al-Ti high-entropy alloy.

[0016] Preferably, the thickness of the Fe-Ni-Al-Ti high-entropy alloy cast plate is 5 mm.

[0017] Preferably, the melting is vacuum arc melting, and is carried out under a protective atmosphere (such as an argon atmosphere) for 5-6 times, so as to improve the uniformity of the alloy components.

[0018] Preferably, the temperature of the homogenization treatment is 1000-1300°C, and the treatment time is 1-3 h.

[0019] Preferably, the temperature of the recrystallization annealing treatment is 1000-1300°C, and the treatment time is 1-3 min.

[0020] Preferably, the temperature of the aging treatment is 700-900°C, and the treatment time is 3-5 h.

[0021] Preferably, the method comprises the following steps:

[0022] (1) Raw material pretreatment: remove the surface stains and oxide skins of the materials before weighing, and then put each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying. According to the component proportion of the target alloy, weigh the high-purity metal raw materials of Fe, Co, Ni, Al and Ti, and accurately weigh these metal raw materials (the purity is not less than 99.9%);

[0023] (2) Vacuum arc melting: put the weighed and dried metal raw materials and titanium ingots for oxygen absorption into a vacuum arc melting furnace. In order to avoid the volatilization of low-melting-point elements and ensure uniform melting, accurately weigh the metal elements in the order of low to high melting point and place them in the pits of a copper mold. Alloy melting is carried out under a protective atmosphere; preferably, the protective atmosphere during the melting process is high-purity argon, and a titanium ingot is burned by arc before alloy melting to consume residual oxygen.

[0024] (3) Alloy suction casting: suck the molten alloy liquid into a 5 mm thick copper mold to cool and form a cast plate of a predetermined shape, to obtain a Co-added Fe-Ni-Al-Ti high-entropy alloy cast plate.

[0025] (4) Homogenization treatment of the obtained cast plate at a first preset temperature for a first preset time; cold rolling treatment is performed on the alloy product after homogenization treatment to obtain a rolled product with a final rolling thickness; the rolled product is placed into a vacuum heat treatment furnace, and recrystallization annealing treatment is performed at a second preset temperature for a second preset time; finally, aging treatment is performed at a third preset temperature for a third preset time; wherein:

[0026] The first preset temperature is in the range of 1000-1300°C.

[0027] The value range of the first preset time length is 1-3 hours.

[0028] The value range of the second preset temperature is 1000-1300 DEG C.

[0029] The value range of the second preset time length is 1-3 minutes.

[0030] The value range of the second preset temperature is 700-900 DEG C.

[0031] The value range of the second preset time length is 3-5 hours.

[0032] The technical principle of the application is as follows:

[0033] The application realizes the technical effect of significant synergistic optimization by regulating the content of Co element in Fe-Ni-Al-Ti high-entropy alloy (FNAL HEAs), and solves the challenges faced by traditional high-entropy alloys in strength-plasticity balance and environmental adaptability. Specifically, on the one hand, Co element is generally beneficial to the formation of FCC phase in the alloy, and the addition of a certain amount of Co element can effectively improve the plasticity of the alloy; on the other hand, in the synergistic optimization of precipitate stability and pinning effect, the introduction of Co element effectively improves the thermal stability of L12 precipitate phase, significantly enhances its resistance to coarsening. At the same time, the addition of Co makes the L21 precipitate phase smaller, strengthens its pinning effect on the grain boundary, effectively hinders the dislocation movement and grain boundary migration, and provides excellent strengthening basis for the alloy; the breakthrough in the synergistic improvement of strength and plasticity lies in the precise control of Co content, which avoids the element segregation and excessive coarsening of precipitate phase caused by high Co. After the appropriate coarsening of L12 phase, the precipitate phase spacing increases, the freedom of dislocation movement increases, and the uniform plastic deformation capacity is enhanced, and the hindering effect of L21 phase on the grain boundary prolongs the work hardening stage, so that the highest strength and good plasticity are achieved. The application creatively realizes the "moderate coarsening" state of L12 and L21 precipitate phases. The distribution of such specific state of precipitate phase, on the one hand, ensures the ultra-high strength of the alloy, and on the other hand, significantly enhances the uniform plastic deformation capacity of the alloy; at the same time, the corrosion resistance is also significantly improved: the existence of Co species in the passivation film of high-entropy alloy is beneficial to the enhancement of corrosion resistance, and the addition of Co element significantly enhances the corrosion resistance of Fe-Ni-Al-Ti-Co high-entropy alloy in corrosive environment (such as chloride ion environment). The alloy after optimization of Co content shows lower corrosion current density and higher corrosion potential, indicating that it forms a more stable and protective passivation film, and the resistance to localized corrosion (such as pitting) is effectively improved; the optimization and control window of composition-process-performance is clear, the application not only reveals the key influence mechanism of Co content on the morphology, size, distribution and stability of L12 and L21 precipitate phases, but also clearly defines the Co content optimization window for obtaining the best comprehensive performance (including mechanical properties and corrosion resistance), which provides direct theoretical basis and practical guidance for the accurate design of subsequent aging treatment process.

[0034] Compared with the prior art, the application has the following advantages and technical effects:

[0035] The present application successfully realizes the synergistic stabilization, moderate coarsening and optimized distribution of L12 and L21 precipitated phases in Fe-Ni-Al-Ti-based high-entropy alloy by innovatively regulating the content of Co, thereby simultaneously obtaining excellent strength, excellent plasticity and significantly improved corrosion resistance. This breakthrough not only reveals unique strengthening and toughening and corrosion resistance mechanisms, but more importantly, provides a highly competitive solution for developing the next generation of high-performance structural materials suitable for aerospace key components, advanced energy equipment, marine engineering and chemical environments requiring harsh comprehensive performance (high strength, high toughness, long service life, corrosion resistance), greatly improving the industrial application potential and market prospects of the alloy system. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the accompanying drawings. In the drawings:

[0037] Figure 1 XRD patterns of the products of Comparative Example 1 and Examples 1-3;

[0038] Figure 2 SEM images of the products of Comparative Example 1 and Examples 1-3, wherein (a) is the SEM image of Comparative Example 1, (b) is the SEM image of Example 1, (c) is the SEM image of Example 2, and (d) is the SEM image of Example 3;

[0039] Figure 3 Engineering stress-strain curves of the products of Examples 1-3 under room temperature tension;

[0040] Figure 4 Polarization curves of the products of Comparative Example 1 and Example 3 in a NaCl solution with a mass fraction of 3.5%, wherein (FeNi) 86 Al7Ti7 is a Fe-Ni-Al-Ti-based high-entropy alloy cast plate in Comparative Example 1, (FeNi) 86 Al7Ti7 hot is FCNAT, (FeCoNi) 86 Al7Ti7 is a Fe-Ni-Al-Ti-based high-entropy alloy cast plate in Example 3 with the addition of Co element, (FeCoNi) 86 Al7Ti7 hot is FCNAT-3. DETAILED DESCRIPTION

[0041] Now, various exemplary embodiments of the present application will be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0042] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of a parameter, unless otherwise stated, the inclusion of either extremity of the range is to be understood as if both are stated. For example, "from 1 to 10" should be interpreted as meaning "from 1 to 10 as well as 1 to 10".

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0044] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples are illustrative only.

[0045] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0046] The Fe-Ni-Al-Ti high-entropy alloy according to the embodiments of the present application includes, in atomic percentage, 0-40% of cobalt (Co), and the content of cobalt is not 0, 20-50% of nickel (Ni), 3-10% of aluminum (Al), and 3-10% of titanium (Ti), and the balance is iron (Fe) and inevitable impurities.

[0047] In the preferred embodiments of the present application, the Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 11-30% of Co, 28-38% of Ni, 7% of Al, and 7% of Ti, and the balance is Fe and inevitable impurities.

[0048] For example, the Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 11% of Co, 37.5% of Ni, 7% of Al, and 7% of Ti, and the balance is Fe and inevitable impurities.

[0049] For example, the Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 20.4% of Co, 32.8% of Ni, 7% of Al, and 7% of Ti, with the balance being Fe and inevitable impurities.

[0050] For example, the Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 28.6% of Co, 28.7% of Ni, 7% of Al, and 7% of Ti, with the balance being Fe and inevitable impurities.

[0051] The embodiment of the present application also provides a preparation method of the Fe-Ni-Al-Ti high-entropy alloy.

[0052] (1) Raw material pretreatment: remove the surface stains and oxide skins of the materials before weighing, and then put each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying. According to the composition ratio of the target alloy, weigh the high-purity metal raw materials of Fe, Co, Ni, Al and Ti, and accurately weigh these metal raw materials (with a purity of not less than 99.9%);

[0053] (2) Vacuum arc melting: put the weighed and dried metal raw materials and titanium ingot for oxygen absorption into a vacuum arc melting furnace. In order to avoid the volatilization of low-melting-point elements and ensure uniform melting, accurately weigh the metal elements in the order of low melting point to high melting point and put them into the pits of the copper mold. Alloy melting is carried out in a protective atmosphere; preferably, the protective atmosphere in the melting process is high-purity argon, and a titanium ingot is ignited and burned before alloy melting to consume residual oxygen;

[0054] (3) Alloy suction casting: suck the molten alloy liquid into a 5mm thick copper mold to cool and form a cast plate with a predetermined shape, to obtain a 5mm thick Co element added Fe-Ni-Al-Ti high-entropy alloy cast plate;

[0055] (4) Homogenization treatment of the obtained cast plate at a first preset temperature for a first preset time; cold rolling treatment is performed on the alloy product after homogenization treatment to obtain a rolled product with a final rolling thickness; the rolled product is placed into a vacuum heat treatment furnace and subjected to recrystallization annealing treatment at a second preset temperature for a second preset time; and finally, aging treatment is performed at a third preset temperature for a third preset time; wherein:

[0056] The first preset temperature is in the range of 1000℃ to 1300℃;

[0057] The first preset time is in the range of 1 to 3h;

[0058] The second preset temperature is in the range of 1000℃ to 1300℃;

[0059] The second preset time length ranges from 1 min to 3 min.

[0060] The second preset temperature ranges from 700 DEG C to 900 DEG C.

[0061] The second preset time length ranges from 3 h to 5 h.

[0062] The metal raw materials used in the embodiments of the application are specifically iron ingots, cobalt ingots, nickel ingots, aluminum ingots and titanium ingots with a purity of greater than or equal to 99.95%.

[0063] Each raw material used in the following embodiments and comparative examples of the application is a commercially available product.

[0064] The technical solutions of the application are further described below through embodiments.

[0065] Embodiment 1

[0066] An Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 11.0% of Co, 37.5% of Ni, 7% of Al and 7% of Ti, and the balance of Fe and inevitable impurities.

[0067] The specific preparation method is as follows:

[0068] (1) Raw material pretreatment: remove the surface stains and oxide skins of the materials before weighing, and then put each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying, weigh the high-purity metal raw materials (with a purity of not less than 99.9%) of Fe, Co, Ni, Al and Ti according to the above atomic percentage;

[0069] (2) Vacuum arc melting: put the weighed and dried metal raw materials and titanium ingots for oxygen absorption into a vacuum arc melting furnace, to avoid the volatilization of low-melting-point elements and ensure uniform melting, put the weighed metal elements in the concave pits of a copper mold in the order of melting point from low to high, and perform alloy melting under a high-purity argon atmosphere, after the melting is completed and cooled, turn over the ingot and re-melt, and repeat the melting of each ingot for 5 times;

[0070] (3) Alloy suction casting: the molten alloy liquid after 5 times of melting in step (2) is sucked into a 5mm-thick copper mold to form a cast plate with a predetermined shape, and a 5mm-thick Co-added Fe-Ni-Al-Ti high-entropy alloy cast plate is obtained.

[0071] (4) homogenizing the obtained cast plate at 1150 °C for 2 h; cold-rolling the alloy product after homogenization by 65% to obtain a rolled product with a final thickness; placing the alloy product into a vacuum heat treatment furnace, recrystallizing annealing at 1150 °C for 2 min; and finally aging at 780 °C for 4 h to obtain a Fe-Ni-Al-Ti-based high-entropy alloy (denoted as FCNAT-1).

[0072] Example 2

[0073] A Fe-Ni-Al-Ti-based high-entropy alloy includes, in atomic percentage, 20.4% of Co, 32.8% of Ni, 7% of Al, and 7% of Ti, with the balance being Fe and inevitable impurities.

[0074] The specific preparation method is as follows:

[0075] (1) Raw material pretreatment: remove surface stains and oxide skins before weighing, and then place each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying, and weigh high-purity metal raw materials (purity not less than 99.9%) of Fe, Co, Ni, Al, and Ti according to the above atomic percentage;

[0076] (2) Vacuum arc melting: place the weighed and dried metal raw materials and titanium ingots for oxygen absorption into a vacuum arc melting furnace, place the weighed metal elements in the concave pits of the copper mold in the order of low melting point to high melting point to avoid quality loss caused by volatilization of low melting point elements and ensure uniform melting, and perform alloy melting under a high-purity argon atmosphere, turn the ingot after melting and cooling to re-melt, and repeat the melting of each ingot for 5 times;

[0077] (3) Alloy suction casting: suction the molten alloy liquid after 5 times of melting in step (2) into a 5 mm thick copper mold to cool and form a cast plate with a predetermined shape, to obtain a 5 mm thick Fe-Ni-Al-Ti-based high-entropy alloy cast plate with added Co elements;

[0078] (4) homogenizing the obtained cast plate at 1150 °C for 2 h; cold-rolling the alloy product after homogenization by 65% to obtain a rolled product with a final thickness; placing the alloy product into a vacuum heat treatment furnace, recrystallizing annealing at 1150 °C for 2 min; and finally aging at 780 °C for 4 h to obtain a Fe-Ni-Al-Ti-based high-entropy alloy (denoted as FCNAT-2).

[0079] Example 3

[0080] A Fe-Ni-Al-Ti high-entropy alloy includes, in atomic percentage, 28.6% of Co, 28.7% of Ni, 7% of Al, and 7% of Ti, and the balance of Fe and inevitable impurities;

[0081] The specific preparation method is:

[0082] (1) Raw material pretreatment: remove the surface stains and oxide skins of the materials before weighing, and then put each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying, weigh the high-purity metal raw materials (the purity is not less than 99.9%) of Fe, Co, Ni, Al and Ti according to the above atomic percentage;

[0083] (2) Vacuum arc melting: put the weighed and dried metal raw materials and titanium ingot for oxygen absorption into a vacuum arc melting furnace, to avoid the volatilization of low-melting-point elements and ensure uniform melting, put the weighed metal elements in the concave pits of the copper mold in the order of low melting point to high melting point, and carry out alloy melting under a high-purity argon atmosphere, after melting and cooling, turn over the ingot and re-melt, repeat the melting of each ingot for 5 times;

[0084] (3) Alloy suction casting: the molten alloy liquid after 5 times of melting in step (2) is sucked into a 5mm thick copper mold to cool and form a cast plate with a predetermined shape, to obtain a 5mm thick Co element added Fe-Ni-Al-Ti high-entropy alloy cast plate;

[0085] (4) Homogenization treatment is carried out on the obtained cast plate at 1150℃ for 2h, 65% cold rolling treatment is carried out on the alloy product after homogenization treatment to obtain a rolled product with a final rolling thickness, the alloy product is placed into a vacuum heat treatment furnace, and recrystallization annealing treatment is carried out at 1150℃ for 2min, and finally aging treatment is carried out at 780℃ for 4h, to obtain a Fe-Ni-Al-Ti high-entropy alloy (denoted as FCNAT-3).

[0086] Example 4

[0087] The same as example 1, the difference is that in step (4), the obtained cast plate is subjected to homogenization treatment at 1000℃ for 3h, 65% cold rolling treatment is carried out on the alloy product after homogenization treatment to obtain a rolled product with a final rolling thickness, the alloy product is placed into a vacuum heat treatment furnace, and recrystallization annealing treatment is carried out at 1300℃ for 1min, and finally aging treatment is carried out at 900℃ for 3h, to obtain a Fe-Ni-Al-Ti high-entropy alloy (denoted as FCNAT-4).

[0088] Example 5

[0089] The same as Example 1, the only difference is that in step (4), the obtained cast plate is subjected to homogenization treatment at 1300℃ for 1h; the alloy product after homogenization treatment is subjected to 65% cold rolling treatment to obtain a rolled product with a final rolling thickness; the alloy product is placed into a vacuum heat treatment furnace and subjected to recrystallization annealing treatment at 1000℃ for 3min; and finally, aging treatment is carried out at 700℃ for 5h to obtain a Fe-Ni-Al-Ti-based high-entropy alloy (denoted as FCNAT-5).

[0090] Comparative Example 1

[0091] A Fe-Ni-Al-Ti-based high-entropy alloy, comprising, in atomic percentage: 43% of Ni, 7% of Al and 7% of Ti, and the balance of Fe and inevitable impurities;

[0092] The specific preparation method is as follows:

[0093] (1) Raw material pretreatment: remove the surface stains and oxide skins of the materials before weighing, and then put each metal raw material into anhydrous ethanol for ultrasonic cleaning and drying, and weigh the high-purity metal raw materials (the purity is not less than 99.9%) of Fe, Ni, Al and Ti according to the above atomic percentage;

[0094] (2) Vacuum arc melting: put the weighed and dried metal raw materials and titanium ingot for oxygen absorption into a vacuum arc melting furnace, put the weighed metal elements in the concave of a copper mold in the order of low melting point to high melting point to avoid quality loss caused by volatilization of low melting point elements and ensure uniform melting, and carry out alloy melting under a high-purity argon atmosphere, turn over the ingot after melting and cooling to re-melt, and repeat the melting of each ingot for 5 times;

[0095] (3) Alloy suction casting: the molten alloy liquid after 5 times of melting in step (2) is sucked into a 5mm thick copper mold to cool and form a cast plate with a predetermined shape, and a Fe-Ni-Al-Ti-based high-entropy alloy cast plate with a thickness of 5mm is obtained;

[0096] (4) The obtained cast plate is subjected to homogenization treatment at 1150℃ for 2h; the alloy product after homogenization treatment is subjected to 65% cold rolling treatment to obtain a rolled product with a final rolling thickness; the alloy product is placed into a vacuum heat treatment furnace and subjected to recrystallization annealing treatment at 1150℃ for 2min; and finally, aging treatment is carried out at 780℃ for 4h to obtain a Fe-Ni-Al-Ti-based high-entropy alloy (denoted as FCNAT).

[0097] Performance test

[0098] (1) The products of Examples 1-3 and Comparative Example 1 are subjected to XRD test

[0099] Figure 1XRD patterns of the products of Comparative Example 1 and Examples 1-3; from Figure 1 The results show that the four FNAT, FCNAT-1, FCNAT-2, FCNAT-3 high-entropy alloys are composed of FCC and L12, L21 precipitated phases.

[0100] (2) Microstructure of the products of Examples 1-3 and Comparative Example 1 was characterized

[0101] Figure 2 SEM images of the products of Comparative Example 1 and Examples 1-3. Among them, (a) is the SEM image of Comparative Example 1, (b) is the SEM image of Example 1, (c) is the SEM image of Example 2, and (d) is the SEM image of Example 3.

[0102] from Figure 2 It can be seen that the FNAT alloy as a whole has large L12 and L21 precipitated phases; Co element is generally conducive to the formation of FCC phase in the alloy, and adding a certain content of Co element can effectively improve the plasticity of the alloy; the addition of Co element is conducive to improving the L12 thermal stability and the ability to resist coarsening, and at the same time, through the addition of Co element, fine and irregular L21 phase is obtained, which is beneficial to strengthening the pinning effect. However, higher Co content will promote element segregation, resulting in an increase in the size of the precipitated phase.

[0103] (3) Tensile property test of the products of Examples 1-3

[0104] The engineering stress-strain curves of the products of Examples 1-3 under room temperature tension are shown in Figure 3 It can be seen that by adding Co element, the plasticity of the material can be effectively improved. The yield strength and ultimate tensile strength of FCNAT-1 alloy are 864.18 MPa and 954.39 MPa, respectively, and the fracture elongation is 2.78%; the yield strength (941.55 MPa), ultimate tensile strength (1480.55 MPa), and fracture elongation (13.1%) of FCNAT-2 alloy are higher; and the yield strength (1229.80 MPa) and ultimate tensile strength (1509.31 MPa) of FCNAT-3 alloy are the highest, and the plastic fracture elongation is the highest, reaching 14.8%. FCNAT-3 has moderately coarsened and uniformly distributed L12 and L21 phases, which together enhance the uniform plastic deformation ability and ensure high strength, achieving high strength and plasticity.

[0105] (4) Electrochemical corrosion test of the products of Example 3 and Comparative Example 1

[0106] Figure 4 The polarization curves of the products of Comparative Example 1 and Example 3 in a NaCl solution with a mass fraction of 3.5% are shown in the figure. (FeNi) 86Al7Ti7 is the Fe-Ni-Al-Ti high-entropy alloy cast plate prepared in step (3) of Comparative Example 1, (FeNi) 86 Al7Ti7 is the FCNAT after heat treatment in step (4), (FeCoNi) 86 Al7Ti7 is the Fe-Ni-Al-Ti high-entropy alloy cast plate (product obtained in step (3)) of Example 3 to which Co element is added, (FeCoNi) 86 Al7Ti7 heat is FCNAT-3 (product obtained in step (4)).

[0107] It can be seen that the self-corrosion potential of the FNAT alloy after heat treatment is -0.72 V, which is slightly higher than the self-corrosion potential of the FNAT alloy in the original state, which is -0.74 V, and the self-corrosion current density of the FNAT alloy after heat treatment is 4.11 × 10 -5 A / cm 2 , which is lower than the self-corrosion current density of the FNAT alloy in the original state, which is 5.72 × 10 -5 A / cm 2 . It can also be seen that the self-corrosion potential of the FCNAT-3 high-entropy alloy after heat treatment is -0.37 V, which is higher than the self-corrosion potential of the FCNAT-3 alloy in the original state, which is -0.45 V, and the self-corrosion current density of the FCNAT-3 alloy after heat treatment is 1.97 × 10 -5 A / cm 2 , which is lower than the self-corrosion current density of the FCNAT-3 alloy in the original state, which is 3.88 × 10 -5 A / cm 2 . It shows that the heat treatment process enhances the corrosion resistance of the high-entropy alloy. The existence of Co species in the passivation film of the high-entropy alloy is beneficial to enhance the corrosion resistance. Whether in the original state or in the heat treated state, the self-corrosion potential of the FCNAT-3 alloy is higher than that of the FNAT alloy, which shows that the addition of Co enhances the corrosion resistance of the FNAT high-entropy alloy.

[0108] In summary, by regulating the Co content in the Fe-Ni-Al-Ti high-entropy alloy, the characteristics of precipitated phases, mechanical properties and corrosion resistance are optimized: Co element is usually beneficial to the formation of FCC phase in the alloy, and the addition of a certain content of Co element can effectively improve the plasticity of the alloy. At the same time, the introduction of Co significantly improves the thermal stability and anti-coarsening ability of L12 phase, and refines L21 phase to enhance the grain boundary pinning effect; by controlling the Co content, element segregation and excessive coarsening of precipitated phases are avoided, and the moderate coarsening of L12 / L21 phase is realized, which breakthroughly takes into account the ultra-high strength and uniform plastic deformation ability; the optimized alloy forms a more stable passivation film in the environment containing chloride ions, the corrosion current is reduced and the potential is increased, and the pitting resistance is significantly improved; in addition, the mechanism of Co content regulation on precipitated phases and the optimal influence on comprehensive performance are clarified, which provides direct theoretical guidance for the design of aging process.

[0109] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An Fe-Ni-Al-Ti based high-entropy alloy, characterized by, comprises, by atomic percentage: 0-40% of cobalt, and the content of cobalt is not 0, further comprises 20-50% of nickel, 3-10% of aluminum and 3-10% of titanium, and the balance is iron and inevitable impurities. 2.The Fe-Ni-Al-Ti based high-entropy alloy according to claim 1, wherein, comprises, by atomic percentage: 11-30% of cobalt, 28-38% of nickel, 7% of aluminum and 7% of titanium, and the balance is iron and inevitable impurities. 3.The Fe-Ni-Al-Ti based high-entropy alloy according to claim 2, characterized in that, comprises, by atomic percentage: 11% of cobalt, 37.5% of nickel, 7% of aluminum and 7% of titanium, and the balance is iron and inevitable impurities. 4.The Fe-Ni-Al-Ti based high-entropy alloy according to claim 2, characterized in that, comprises, by atomic percentage: 20.4% of cobalt, 32.8% of nickel, 7% of aluminum and 7% of titanium, and the balance is iron and inevitable impurities. 5.The Fe-Ni-Al-Ti based high-entropy alloy according to claim 2, wherein, comprises, by atomic percentage: 28.6% of cobalt, 28.7% of nickel, 7% of aluminum and 7% of titanium, and the balance is iron and inevitable impurities.

6. A method for producing the Fe-Ni-Al-Ti-based high-entropy alloy according to any one of claims 1 to 5, characterized by, comprises the following steps: The raw materials are weighed by atomic percentage, mixed uniformly, smelted and suction cast to obtain Fe-Ni-Al-Ti high-entropy alloy cast plate. The Fe-Ni-Al-Ti high-entropy alloy cast plate is subjected to homogenization treatment, cold rolling treatment, crystallization annealing treatment and aging treatment in sequence to obtain the Fe-Ni-Al-Ti high-entropy alloy.

7. The method of claim 6, wherein the Fe-Ni-Al-Ti based high-entropy alloy is prepared by the steps of: preparing a mixed solution of Fe, Ni, Al, and Ti; and performing a vacuum evaporation process on the mixed solution. The smelting is carried out under a protective atmosphere, and the smelting is carried out 5-6 times.

8. The method of claim 6, wherein the Fe-Ni-Al-Ti based high-entropy alloy is prepared by the steps of: preparing a mixed solution of Fe, Ni, Al, and Ti; and performing a vacuum evaporation process on the mixed solution. The temperature of the homogenization treatment is 1000-1300℃, and the treatment time is 1-3h.

9. The method of claim 6, wherein the Fe-Ni-Al-Ti based high-entropy alloy is prepared by the steps of: preparing a mixed solution of Fe, Ni, Al, and Ti; and performing a vacuum evaporation process on the mixed solution. The temperature of the crystallization annealing treatment is 1000-1300℃, and the treatment time is 1-3min.

10. The method of claim 6, wherein the Fe-Ni-Al-Ti based high-entropy alloy is prepared by the steps of: preparing a mixed solution of Fe, Ni, Al, and Ti; and performing a vacuum evaporation process on the mixed solution. The temperature of the aging treatment is 700-900℃, and the treatment time is 3-5h.

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