Low-activation high-strength anti-radiation high-entropy alloy and preparation method thereof

Abstract

The invention relates to the technical field of alloy materials, and provides a low-activation high-strength anti-radiation high-entropy alloy and a preparation method thereof. The components of the alloy are (Fe < 3 > < 0.4 > Cr < 3 > V < 3 > < 0.3 > Ti < 3.0 > Ta < 3.0 > W < 3.0 >) < 100-x > C < x >, and x is larger than or equal to 0.5 and smaller than or equal to 7. The yield strength of the high-entropy alloy at the room temperature is larger than 1300 MPa, the plastic deformation amount is 15% or above, the room-temperature brittleness is greatly relieved, and compared with an existing low-activation high-entropy alloy, the low-activation high-entropy alloy has the advantages of being high in strength and toughness, low in cost and the like. In addition, after high-energy low-flux He plasma irradiation, the anti-irradiation performance of the alloy is improved, and the mechanical performance and the irradiation performance of the material can be regulated and controlled through alloy components. The low-activation high-entropy alloy serves as a nuclear material of a fusion reactor and a new-generation fission reactor, the problems that an existing traditional low-activation nuclear material is high in cost, insufficient in mechanical property and the like are solved, and application and development of nuclear energy in the fields of aviation and national defense can be further promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and particularly to a high-entropy alloy with low activation, high strength and radiation resistance, and a preparation method thereof. Background Art

[0002] The development of nuclear energy is of great significance for solving the world's energy problems. With the continuous in-depth research and development of the fourth-generation nuclear fission reactor and the International Thermonuclear Experimental Reactor, the service environment faced by nuclear structural materials is becoming increasingly complex and extreme, including long-term high temperature, high pressure, high-dose neutron irradiation, strong corrosion, friction and wear, etc., making conventional structural materials unable to meet the service requirements of advanced nuclear reactors, and there is an urgent need to develop new structural materials with low activation characteristics.

[0003] Among the currently actually served low-activation materials, low-activation steel has high radiation resistance and low thermal expansion coefficient, and is easy to be mass-produced. However, its strength drops sharply at high temperatures, making it difficult to be used permanently in the nuclear energy field; vanadium alloys have high high-temperature strength and good hot plasticity, but they have problems such as easy oxidation at high temperatures and difficult forming and welding, which limit their large-scale application; silicon carbide composites meet the high-temperature strength requirements, but they are difficult to manufacture and process, and are not easy to connect and seal. Therefore, low-activation radiation-resistant alloy materials for the fourth-generation nuclear fission reactor and fusion reactor need to be further designed and developed.

[0004] In recent years, high-entropy alloys have become one of the powerful candidate materials due to their characteristics such as low activation, high strength, good ductility, radiation resistance and corrosion resistance. In existing research, alloys such as CoCrFeNi, FeNiMnCr, Ti 2 ZrHfV 0.5 Mo 0.2 etc. have obvious advantages in suppressing dislocation loops, helium bubbles, radiation hardening and swelling during irradiation, and have good radiation resistance. However, on the one hand, the existing research on high-entropy alloys does not fully consider the characteristics of low activation and radiation resistance of the alloys. For example, in the high-entropy alloy prepared in Patent No. CN118186276B, although the Co element is removed, it still contains the highly active Ni element; on the other hand, refractory high-entropy alloys, which are more suitable as nuclear materials, still have the problem of high cost. For example, in Patent No. CN115896579B, more than 30 mol% of Ta and W elements are added, and the manufacturing cost of the material increases sharply, and the cost needs to be further controlled. The influence of C element on the microstructure and properties of BCC-structured low-activation alloys remains to be improved. For example, in Patent No. CN115896580B, up to 2 mol% of C content is added to WTaTiV, but no more is added, and the radiation resistance of the alloy is not explored. Therefore, it is of great significance to design and develop high-entropy alloys that take into account low activation and radiation resistance, high strength and toughness, and low cost. Summary of the Invention

[0005] In view of this, the present invention proposes a high entropy alloy with low activation, high strength and radiation resistance and a preparation method thereof. A small amount of Ti, Ta, W and C elements are introduced into the FeCrV alloy, and the structure and properties of the alloy are regulated by changing the C content, thereby alleviating the room temperature brittleness of the alloy and improving the radiation resistance, aiming to solve the problems of room temperature brittleness and poor radiation resistance of existing high entropy alloys.

[0006] The technical solution of the present invention is implemented as follows: In the first aspect, the present invention provides a low-activation, high-strength, radiation-resistant high-entropy alloy, the composition of the alloy is (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x , wherein x is a molar percentage, 0.5≤x≤7, and the remaining alloying elements maintain a fixed ratio, and the alloy will precipitate a small amount of carbide.

[0007] The low-activation, high-strength, radiation-resistant high-entropy alloy of the present invention has the following characteristics:

[0008] (a) Room temperature compressive yield strength is 1200~1800MPa,

[0009] (b) The compressive strain at room temperature is greater than 15%,

[0010] (c) Under low-energy, high-flux He plasma irradiation, the addition of trace element C improves the radiation resistance of the alloy.

[0011] In a second aspect, the present invention provides a method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy, comprising the following steps: preparing metal single substances and partial alloys of each element as raw materials according to the proportions of the constituent elements of the alloy, and preparing a low-activation high-entropy alloy by vacuum arc melting and adjusting the melting order.

[0012] The specific steps are as follows:

[0013] S1, selecting Fe blocks, FeC alloy blocks, Cr sheets, V particles, Ti particles, W particles, and Ta particles as raw materials for batching;

[0014] S2, placing the ingredients of S1 into a vacuum arc melting furnace, evacuating the furnace and introducing protective gas for arc melting;

[0015] S3, after the smelting is completed, the alloy melt is cooled with a water-cooled copper mold to obtain a high entropy alloy.

[0016] On the basis of the above technical solutions, preferably, in step S2, during smelting, first smelt W particles and Ta particles to obtain a W-Ta alloy, then put in V particles for smelting to obtain a W-Ta-V alloy, and finally add iron blocks, FeC alloy blocks, Cr flakes and Ti particles for smelting to obtain a high-entropy alloy.

[0017] If the smelting is not carried out in the above specified order, problems such as serious evaporation of alloy elements, inaccurate composition and difficulty in uniform smelting will occur. The reason is that except for W and Ta elements, the boiling points of other elements are lower than the melting point of W, and serious evaporation loss will occur during simultaneous smelting. The melting point of the W-Ta alloy is lower than the boiling point of V, which can effectively reduce the loss. Similarly, the melting point of the W-Ta-V alloy is further reduced, making it easier to smelt and mix evenly with other elements and not easily burned.

[0018] On the basis of the above technical solutions, preferably, in step S2, each time an alloy is smelted, the alloy ingot is kept for 3-5 minutes after being completely melted, then the alloy ingot is turned over and remelted, and the remelting is repeated 3-5 times. During smelting, the current is kept at 18-20 A.

[0019] On the basis of the above technical solutions, preferably, in step S2, the smelting temperature is 3000 °C to 3500 °C.

[0020] On the basis of the above technical solutions, preferably, in step S2, the vacuum degree during smelting is 3×10 -3 Pa to 5×10 -3 Pa.

[0021] If the vacuum degree is not high enough during smelting, after exceeding 5×10 -3 MPa, impurity phases such as titanium oxide and titanium nitride are likely to appear in the alloy (see Figure 5 ), deteriorating the alloy performance. The influence of the protective gas atmosphere pressure on impurity gases is the same.

[0022] On the basis of the above technical solutions, preferably, in step S2, the protective gas during smelting is argon with a purity of 99.999%, and the atmosphere pressure is -0.04 to -0.05 MPa.

[0023] On the basis of the above technical solutions, preferably, before smelting, first polish the raw materials to remove the surface oxide scale, and then ultrasonically clean and dry them in absolute ethanol.

[0024] On the basis of the above technical solutions, preferably, the purity of the iron blocks, FeC alloy blocks, Cr flakes, V particles, Ti particles, W particles, and Ta particles is ≥99.95 wt%, and the FeC alloy block contains 5 wt% C.

[0025] Thirdly, the present invention provides an application of a high-entropy alloy with low activation, high strength and radiation resistance in structural materials and / or nuclear radiation-resistant low-activation materials.

[0026] The high-entropy alloy with low activation, high strength and radiation resistance and its preparation method of the present invention have the following beneficial effects compared with the prior art:

[0027] (1) The novel (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x -series high-entropy alloy controls the mechanical properties of the alloy by controlling the content of C element. As the C content increases, the plasticity and yield strength of the alloy first increase and then decrease. When x = 1, the yield strength is the highest, reaching 1720 MPa; when x = 5, the plasticity is the best, and the plastic deformation amount reaches 35%. Generally, it shows high strength and high toughness. This phenomenon shows an inconsistent law compared with traditional alloys, providing experimental data support for the regulation of the mechanical properties of low-activation high-entropy alloys by C element.

[0028] (2) The (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x -series high-entropy alloy enhances the lattice distortion degree of the alloy, enhances the retardation diffusion effect of the alloy and in-situ precipitated carbides by introducing C element, and improves the radiation resistance of the alloy. Through irradiation experiments, it is found that when x = 5, the alloy has the best radiation resistance, and the generated nano-villus structure layer is the thinnest, providing a reference for regulating the radiation resistance of the alloy.

[0029] (3) The present invention prepares the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x high-entropy alloy by vacuum arc melting of elemental and alloy mixtures. It has a BCC solid solution structure with accurate composition and stable structure, contains a small amount of Laves and carbide second phases. Compared with powder metallurgy, this preparation process greatly improves production efficiency, introduces fewer impurity elements, and no impurity phases are formed in the alloy.

[0030] (4) By controlling the purity of raw materials, introducing C element through master alloy, adjusting the melting sequence, and designing the vacuum degree, purity of protective gas, and pressure of protective gas atmosphere during arc melting, the present invention can effectively protect the alloy from oxidation during preparation, avoid raw material loss while ensuring sufficient melting of raw materials for metallurgical reactions, and make the finally prepared alloy have precise composition and few impurities.

[0031] (5) The present invention focuses on the room-temperature mechanical properties and radiation resistance of high-entropy alloys. The designed alloys have a yield strength greater than 1300 MPa at room temperature, a plastic deformation of more than 15%, and greatly reduced room-temperature brittleness. Compared with existing low-activation high-entropy alloys, the alloys have the advantages of high strength, high toughness, and low cost. After irradiation with high-energy and low-flux He plasma, it is found that with the increase of C content, the radiation resistance of the alloy is improved, and the mechanical properties and radiation resistance of the material can be regulated by alloy composition. As nuclear materials for fusion reactors and new-generation fission reactors, the low-activation high-entropy alloys of the present invention solve the problems of high cost and insufficient mechanical properties of current traditional low-activation nuclear materials, and can further promote the application and development of nuclear energy in the fields of aviation and national defense. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0033] Figure 1 Room-temperature compression curves of (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x series high-entropy alloys prepared in each embodiment of the present invention.

[0034] Figure 2 Room-temperature XRD diffraction analysis diagrams of (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x series high-entropy alloys prepared in each embodiment of the present invention.

[0035] Figure 3 For (Fe 30.4 Cr30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 95 C 5 SEM micrograph of the alloy material after irradiation with low-energy high-flux He plasma.

[0036] Figure 4 For Comparative Example 3, two-step melting of Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 Alloy ingot after alloy crushing.

[0037] Figure 5 It is the titanium oxynitride impurity phase that appears in the alloy when the vacuum degree is too low. Detailed implementation manners

[0038] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] A kind of low-activation high-strength anti-irradiation high-entropy alloy provided by the present invention, the composition expression of the alloy is (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x , where x is the mole percentage, and 0.5 ≤ x ≤ 7.

[0040] The low-activation high-entropy alloy is mainly composed of low-activation elements of transition groups such as Ti, V, Cr, Mn, Fe, Ta, and W, and is usually a body-centered cubic structure. The existing low-activation high-entropy alloy materials still have room-temperature brittleness, and at the same time, the irradiation performance has not been verified in the laboratory. The present invention develops a new type of (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C xA series of alloys, by changing the carbon element content in the alloy system, to regulate the microstructure and properties of the alloy, it is found that carbon exhibits excellent mechanical properties and anti-irradiation properties within the range of molar percentage less than or equal to 7.

[0041] The present invention further discovers that with the increase of carbon content, the yield strength and plastic deformation of the alloy show a trend of first increasing and then decreasing. The yield strength of the alloy reaches the highest at x = 1, and the plastic deformation reaches the highest at x = 5.

[0042] This may be caused by two factors: Firstly, when carbon diffuses into the high-entropy alloy, it will react with metal elements to form some harder and more stable carbides, such as TiC, TaC, etc., which are distributed throughout the high-entropy alloy, forming a second phase that hinders the movement of dislocations in the alloy. At the same time, the precipitated carbides can partially hinder grain growth and refine the grains, increasing the yield strength; Secondly, part of the carbon will dissolve into the solid solution, intensifying the lattice distortion degree and increasing the resistance to dislocation movement, resulting in an increase in yield strength; However, when the carbon content increases, it will strengthen the retardation diffusion effect in the high-entropy alloy, inhibit the precipitation behavior of the alloy, greatly reduce the formation of carbides. On the contrary, carbon atoms tend to aggregate, leading to coarsening of some grains, reducing the yield strength of the alloy.

[0043] The improvement of plastic deformation may be because carbon elements are extremely easy to react with elements such as Ti and Ta in the Laves phase in the alloy to form M(Ti, Ta)C carbides, regulating the content, morphology and distribution of the brittle Laves phase in the alloy, continuously improving the plasticity; after the carbon content continues to rise, the precipitation of carbides has reached the peak, and at the same time the carbon solubility in the solid solution has reached saturation, and the excess carbon atoms begin to exist in the form of simple substances, resulting in grain coarsening and causing a decrease in plasticity.

[0044] The present invention further discovers that the anti-irradiation performance of the low-activation high-entropy alloy is improved. There are two possible reasons for this: Firstly, the compositional complexity and lattice distortion of the high-entropy alloy reduce the defect migration rate, change the defect migration behavior, effectively inhibit cavity swelling. At the same time, the retardation diffusion effect of the alloy slows down helium diffusion, which can effectively inhibit the growth of the fluff structure on the free surface and the formation and rupture of helium bubbles, improving the anti-irradiation performance of the alloy; Secondly, the introduced carbon element plays a role in inhibiting the expansion of thermal spikes, enhancing the retardation diffusion effect of the high-entropy alloy, promoting the recombination of point defects, pinning dislocation loops, etc., to improve the anti-irradiation performance of the alloy.

[0045] Specifically, a preparation method of a low-activation high-entropy alloy provided by an embodiment of the present invention includes the following steps:

[0046] S1. Composition design and batching

[0047] Design (Fe 30.4 Cr 30.3 V30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x The chemical composition of the low-activation high-entropy alloy, Fe, Cr, V, Ti, Ta and W elements are mixed in a fixed molar percentage and remain unchanged, x is a molar percentage greater than or equal to 0.5 and less than or equal to 7. The metal single substance and alloy of each element are prepared as raw materials according to the ratio of each component element of the alloy.

[0048] Preferably, the raw materials include Fe blocks with a purity of 99.95wt.%, FeC alloy blocks with a purity of 99.95wt.% (C content 5wt.%), Cr sheets with a purity of 99.95wt.%, V particles with a purity of 99.95wt.%, Ti particles with a purity of 99.95wt.%, W particles with a purity of 99.95wt.%, and Ta particles with a purity of 99.95wt.%. Further, the raw materials are polished to remove surface oxide scales, and then ultrasonically cleaned in anhydrous ethanol, and then smelted after drying.

[0049] S2. Vacuum arc melting

[0050] Put the raw materials prepared in step S1 into a vacuum arc melting furnace for vacuum arc melting to prepare a low-activation high-entropy alloy. Specifically, before the arc melting operation, check and confirm that the water circuit can work normally, and then clean the cavity and crucible of the vacuum furnace. Put the raw materials in the corresponding stations, and at the same time, put a Ti ingot on the center station for further deoxidation. After closing all valves of the furnace, evacuate to a vacuum degree of 3×10 -3 Pa~5×10 -3 Pa, and then argon gas with a purity of 99.999% is passed into the vacuum chamber until the chamber pressure is -0.05MPa. After adjusting the position of the Ti ingot in the melting chamber, the arc is started. After melting the Ti ingot twice to remove the residual oxygen, the arc is moved to the raw material station for melting.

[0051] It should be noted that the melting points of W and Ta elements are too different from those of other elements, so they should be smelted in steps. The smelting order is: W and Ta are smelted to obtain W-Ta alloy, W-Ta alloy is smelted with V to obtain W-Ta-V, and W-Ta-V is smelted with Fe, FeC, Cr, and Ti to obtain the high entropy alloy of the present invention.

[0052] The raw materials are melted until completely molten. After the alloy melt cools down, it is turned over, and then arc melting is continued. Each time, after the alloy raw materials are completely melted, it is maintained for 3 - 5 minutes, and this melting process is repeated 3 - 5 times to ensure its uniformity. Among them, the melting temperature can be controlled between 3000 °C and 3500 °C. After the melting is completed, the alloy melt is cooled with a water-cooled copper mold. After closing the arc melting furnace and opening the air release valve to fill it with gas until the atmospheric pressure, the alloy ingot is taken out, and thus a low-activation high-entropy alloy is obtained.

[0053] The above technical solutions are described in detail below in conjunction with specific embodiments.

[0054] Example 1

[0055] This example provides a high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 95 C 5 , and its preparation method is as follows:

[0056] S1. Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V grains with a purity of 99.95 wt.%, Ti grains with a purity of 99.95 wt.%, W grains with a purity of 99.95 wt.%, and Ta grains with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W grains, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 95 C 5 (denoted as C5) into a mass ratio, calculate the mass of C element required, then obtain the mass of FeC alloy, and further obtain the masses of Fe, Cr, V, Ti, and Ta required. According to this, weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V grains, Ti grains, and Ta grains for arc melting use.

[0057] The raw materials are polished to remove the surface oxide scale, and then ultrasonically cleaned in absolute ethanol and dried.

[0058] S2. Put the prepared raw materials into an arc melting furnace. Due to the difference in melting points, melting W, Ta, and V together will cause a large amount of V to burn and evaporate or W and Ta not to melt completely. Therefore, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy. Then, put V particles for melting to obtain a W-Ta-V alloy. Finally, melt it with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0059] The temperature during melting is 3500 °C. Vacuum is pumped to 3×10 -3 Pa, and then argon with a purity of 99.999% is introduced into the vacuum chamber until the chamber pressure is -0.05 MPa. Arc melting is carried out on the raw materials. After the alloy ingot at the station is completely melted, it is kept for 4 minutes. Subsequently, the alloy ingot is turned over with a turning rod and remelted. Melting is carried out 4 times, and the melting current is kept at 18 A. The above melting process is repeated for each melting of the alloy. After melting, it is cooled with a water-cooled copper mold, and the alloy ingot is taken out to obtain a low-activation high-entropy alloy.

[0060] Perform performance tests on the high-entropy alloy prepared in Example 1 as follows:

[0061] (1) Room-temperature compressive mechanical property test: Use wire cutting to cut the alloy ingot into cylindrical specimens with a diameter of 3 mm and a height of 6 mm. Polish the surfaces at both ends of the specimens to ensure they are smooth and flat. Use an MTS C45.105EY multi-material mechanical property tester to conduct a uniaxial compression test on the specimens to obtain the stress-strain curves of the specimens. During the compression process, the strain rate of the specimens is 1×10 -3 s -1 , and to ensure the accuracy of the data, at least 6 specimens are tested for each group of samples.

[0062] (2) Plasma irradiation experiment: Use a linear plasma device to conduct a He ion irradiation experiment on a 10 mm×10 mm×1 mm sheet sample. The gas pressure for plasma generation is 3.0×10 -2 Pa, the discharge power is 0.9 - 1 kW. During the irradiation process, the temperature of the sample is measured by a thermocouple at the back end to be 500 - 540 °C. The ion flux Flux = 3.967×10 21 ions / m 2 s, the incident energy is 50 eV, the irradiation time is 10 minutes, and the irradiation dose is 2.4×10 24 ions / m 2After irradiation, a GeminiSEM 300 scanning electron microscope was used to observe the morphological structure and growth thickness of the nano-villi on the sample surface. During irradiation, vacancies and pores in the material itself can trap He atoms, form He bubbles, and aggregate to form surface blistering. The diffusion and aggregation of a large number of nano-He bubbles cause the material surface to burst and swell, resulting in the generation of nano-villi structures. The nano-villi structures seriously affect the physical and chemical properties of the material, such as thermal conductivity and mechanical properties. Therefore, it is necessary to inhibit the generation of this type of irradiation damage and reduce the thickness of the nano-villi layer.

[0063] Figure 1 shows the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 95 C 5 alloy (denoted as C5 in the figure) at room temperature. It can be seen that the yield strength of the alloy is 1300 MPa and the plastic deformation is about 35%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villi structure generated on the surface of this alloy is 230 nm, and the effect of this sample is the best. Figure 3 Shows the average thickness of the nano-villi structure of the irradiation damage of C5.

[0064] Example 2

[0065] This example provides a low-activation high-strength anti-irradiation high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99 C 1 , and its preparation method is as follows:

[0066] S1, using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V grains with a purity of 99.95 wt.%, Ti grains with a purity of 99.95 wt.%, W grains with a purity of 99.95 wt.%, and Ta grains with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W grains, and then according to (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99 C 1Convert the molar percentage of each element in (denoted as C1) into a mass ratio, calculate the mass of C element required, and then obtain the mass of FeC alloy. Furthermore, obtain the masses of Fe, Cr, V, Ti, and Ta required. Weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V grains, Ti grains, and Ta grains for arc melting.

[0067] Grind the raw materials to remove the surface oxide scale, and then perform ultrasonic cleaning treatment in anhydrous ethanol and dry completely.

[0068] S2, Put the prepared raw materials into the arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy, then put V grains for melting to obtain a W-Ta-V alloy, and finally melt with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0069] The temperature during melting is 3500 °C. Pump the vacuum to 3×10 -3 Pa, and then introduce argon with a purity of 99.999% into the vacuum chamber until the chamber pressure is -0.05 MPa. Perform arc melting on the raw materials. The alloy ingot at the station remains for 4 minutes after being completely melted, and then turn the alloy ingot over with a turning rod and remelt it. Remelt 4 times, and keep the melting current at 18 A. Repeat the above melting process for each melting of the alloy. After melting, cool with a water-cooled copper mold and take out the alloy ingot to obtain a low-activation high-entropy alloy.

[0070] According to the same method as in Example 1, test the room-temperature mechanical properties and irradiation properties of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99 C 1 alloy prepared in this example. Figure 1 Shows the compressive stress-strain curve at room temperature of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99 C 1 alloy (denoted as C1 in the figure). It can be seen that the yield strength of the alloy is 1720 MPa, and the plastic deformation amount is about 17%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villus structure generated on the surface of this alloy is 310 nm.

[0071] Example 3

[0072] This embodiment provides a high-entropy alloy with low activation, high strength, and radiation resistance (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ), and its preparation method is as follows: 99.5 C 0.5 , and the specific steps are as follows:

[0073] Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V granules with a purity of 99.95 wt.%, Ti granules with a purity of 99.95 wt.%, W granules with a purity of 99.95 wt.%, and Ta granules with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W granules, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99.5 C 0.5 (denoted as C0.5) into mass ratio, calculate the mass of C element required, and then obtain the mass of FeC alloy, and further obtain the masses of Fe, Cr, V, Ti, and Ta required. Weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V granules, Ti granules, and Ta granules for arc melting.

[0074] Grind the raw materials to remove the surface oxide scale, and then perform ultrasonic cleaning treatment in anhydrous ethanol and dry them.

[0075] S2, Put the prepared raw materials into an arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy, then put V granules for melting to obtain a W-Ta-V alloy, and finally melt with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0076] The temperature during melting is 3500 °C, evacuate to 3×10 -3 Pa, and then introduce argon with a purity of 99.999% into the vacuum chamber until the chamber pressure is -0.05 MPa, and perform arc melting on the raw materials. The alloy ingot at the station is kept for 4 min after complete melting, and then the alloy ingot is turned over with a turning rod and remelted. The melting is carried out 4 times, and the melting current is kept at 18 A. Repeat the above melting process for each melting of the alloy. After melting, cool with a water-cooled copper mold, take out the alloy ingot, and obtain the low-activation high-entropy alloy.

[0077] The room-temperature mechanical properties and irradiation properties of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99.5 C 0.5 alloy prepared in this example are tested. Figure 1 Figure 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 99.5 C 0.5 alloy (denoted as C0.5 in the figure) at room temperature shows a compressive stress-strain curve. It can be seen that the yield strength of the alloy is 1700 MPa and the plastic deformation is about 17%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villus structure generated on the surface of this alloy is 330 nm.

[0078] Example 4

[0079] This example provides a low-activation, high-strength and radiation-resistant high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 97 C 3 , and its preparation method is as follows:

[0080] S1. Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V grains with a purity of 99.95 wt.%, Ti grains with a purity of 99.95 wt.%, W grains with a purity of 99.95 wt.%, and Ta grains with a purity of 99.95 wt.% as raw materials, first weigh 4 g of W grains, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 97 C 3 (denoted as C3) into mass ratio, calculate the mass of C element required, then obtain the mass of FeC alloy, and further obtain the masses of Fe, Cr, V, Ti, and Ta required. Weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V grains, Ti grains, and Ta grains for arc melting.

[0081] The raw materials are polished to remove the surface scale, and then ultrasonically cleaned in absolute ethanol and dried completely.

[0082] S2. Put the prepared raw materials into an arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy, then put V particles for melting to obtain a W-Ta-V alloy, and finally melt with Fe, FeC, Cr, Ti raw materials to obtain the sample of this embodiment.

[0083] The temperature during melting is 3500 °C, evacuate to 3×10 -3 Pa, and then introduce argon with a purity of 99.999% into the vacuum chamber until the chamber pressure is -0.05 MPa, and carry out arc melting on the raw materials. The alloy ingot at the station is kept for 4 minutes after being completely melted, and then the alloy ingot is turned over with a turning rod and remelted. The melting is carried out 4 times, and the melting current is kept at 18 A. Repeat the above melting process for each melting of the alloy. After the melting is completed, it is cooled with a water-cooled copper mold, and the alloy ingot is taken out to obtain a low-activation high-entropy alloy.

[0084] According to the same method as in Example 1, test the room-temperature mechanical properties and irradiation properties of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 97 C 3 alloy. Figure 1 Shows the compression stress-strain curve of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 97 C 3 alloy (denoted as C3 in the figure) at room temperature. It can be seen that the yield strength of the alloy is 1640 MPa, and the plastic deformation is about 24%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villus structure generated on the surface of this alloy is 270 nm.

[0085] Example 5

[0086] This embodiment provides a low-activation, high-strength and radiation-resistant high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C7 , and its preparation method is as follows:

[0087] S1. Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V grains with a purity of 99.95 wt.%, Ti grains with a purity of 99.95 wt.%, W grains with a purity of 99.95 wt.%, and Ta grains with a purity of 99.95 wt.% as raw materials, first weigh 4 g of W grains, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 (denoted as C7) into a mass ratio, calculate the mass of C element required, then obtain the mass of FeC alloy, and further obtain the masses of required Fe, Cr, V, Ti, and Ta. Weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V grains, Ti grains, and Ta grains accordingly for arc melting.

[0088] Grind the raw materials to remove the surface oxide scale, and then perform ultrasonic cleaning treatment in anhydrous ethanol and dry completely.

[0089] S2. Put the prepared raw materials into an arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy, then put V grains for melting to obtain a W-Ta-V alloy, and finally melt with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0090] The temperature during melting is 3500 °C, evacuate to 3×10 -3 Pa, then introduce argon with a purity of 99.999% into the vacuum chamber until the chamber pressure is -0.05 MPa, and perform arc melting on the raw materials. The alloy ingot at the station is kept for 4 min after being completely melted, then turn the alloy ingot over with a turning rod and remelt it. Remelt 4 times, and keep the melting current at 18 A. Repeat the above melting process for each melting of the alloy. After melting, cool with a water-cooled copper mold, take out the alloy ingot, and thus obtain a low-activation high-entropy alloy.

[0091] According to the same method as in Example 1, for the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7The room-temperature mechanical properties and irradiation properties of the alloy are tested. Figure 1 shows the 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 compression stress-strain curve of the alloy (denoted as C7 in the figure) at room temperature. It can be seen that the yield strength of the alloy is 1400 MPa and the plastic deformation is about 26%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villus structure generated on the surface of this alloy is 340 nm.

[0092] Example 6

[0093] This example provides a low-activation, high-strength and anti-irradiation high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 , and its preparation method is as follows:

[0094] S1. Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V grains with a purity of 99.95 wt.%, Ti grains with a purity of 99.95 wt.%, W grains with a purity of 99.95 wt.%, and Ta grains with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W grains, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 (denoted as C7) into mass ratio, calculate the mass of C element required, then obtain the mass of FeC alloy, and further obtain the masses of Fe, Cr, V, Ti, and Ta required. Weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V grains, Ti grains, and Ta grains accordingly for arc melting.

[0095] Grind the raw materials to remove the surface oxide scale, and then perform ultrasonic cleaning treatment in anhydrous ethanol and dry them.

[0096] S2. Put the prepared raw materials into an arc melting furnace. Due to the melting point differences, the melting process needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy. Then put V particles for melting to obtain a W-Ta-V alloy. Finally, melt with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0097] During melting, the temperature is 3000 °C. Vacuum is pumped to 4×10 -3 Pa, and then argon with a purity of 99.999% is introduced into the vacuum chamber until the chamber pressure is -0.04 MPa. Arc melting is carried out on the raw materials. After the alloy ingot at the station is completely melted, it is maintained for 3 minutes. Subsequently, the alloy ingot is turned over with a turning rod and remelted. The melting is carried out 5 times, and the melting current is maintained at 19 A. The above melting process is repeated for each melting of the alloy. After melting, it is cooled with a water-cooled copper mold, and the alloy ingot is taken out to obtain the low-activation high-entropy alloy.

[0098] Example 7

[0099] This embodiment provides a low-activation, high-strength, radiation-resistant high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 , and its preparation method is as follows:

[0100] S1. Using Fe blocks with a purity of 99.95 wt.%, Fe-C (C content 5 wt.%) alloy blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V particles with a purity of 99.95 wt.%, Ti particles with a purity of 99.95 wt.%, W particles with a purity of 99.95 wt.%, and Ta particles with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W particles, and then convert the molar percentage of each element in (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 93 C 7 (denoted as C7) into mass ratios, calculate the mass of the required C element, and then obtain the mass of the FeC alloy. Furthermore, obtain the masses of the required Fe, Cr, V, Ti, and Ta, and weigh the corresponding masses of Fe blocks, FeC alloy blocks, Cr sheets, V particles, Ti particles, and Ta particles accordingly for arc melting use.

[0101] Grind the raw materials to remove the surface oxide scale, and then carry out ultrasonic cleaning treatment in anhydrous ethanol and dry completely.

[0102] S2. Put the prepared raw materials into an arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, put Ta and W into one station for melting to obtain a W-Ta alloy, then put V particles for melting to obtain a W-Ta-V alloy, and finally melt with Fe, FeC, Cr, and Ti raw materials to obtain the sample of this embodiment.

[0103] The temperature during melting is 3300 °C. Vacuum is pumped to 5×10 -3 Pa, and then argon with a purity of 99.999% is introduced into the vacuum chamber until the chamber pressure is -0.045 MPa. Arc melting is carried out on the raw materials. The alloy ingot at the station is kept for 5 minutes after being completely melted, and then the alloy ingot is turned over with a turning rod and remelted. The melting is carried out 3 times, and the melting current is kept at 20 A. The above melting process is repeated for each melting of the alloy. After melting, it is cooled with a water-cooled copper mold, and the alloy ingot is taken out to obtain a low-activation high-entropy alloy.

[0104] Figure 2 Shows the XRD diffraction analysis patterns of the (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x series high-entropy alloys prepared in each embodiment of the present invention. The results show that the high-entropy alloy is mainly a BCC solid solution, accompanied by a little second phase. When x≤1, there are diffraction peaks of the HCP phase in the pattern, indicating the presence of the HCP phase in the alloy; when x≥1, the diffraction peaks of the HCP phase in the pattern disappear, and carbide diffraction peaks appear, indicating that the introduction of C element inhibits the appearance of the HCP phase and promotes the formation of carbides.

[0105] Comparative Example 1

[0106] The comparative example provides an alloy Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 , and its preparation method is as follows:

[0107] S1. Using Fe blocks with a purity of 99.95 wt.%, Cr sheets with a purity of 99.95 wt.%, V particles with a purity of 99.95 wt.%, Ti particles with a purity of 99.95 wt.%, W particles with a purity of 99.95 wt.%, and Ta particles with a purity of 99.95 wt.% as raw materials. First, weigh 4 g of W particles, and then according to Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta3.0 W 3.0 (denoted as C0), the molar percentage of each element is converted into a mass ratio to obtain the masses of the required Fe, Cr, V, Ti, and Ta. Accordingly, Fe blocks, Cr sheets, V grains, Ti grains, and Ta grains with corresponding masses are weighed for arc melting use.

[0108] The raw materials are polished to remove the surface oxide scale, and then subjected to ultrasonic cleaning treatment in anhydrous ethanol and dried.

[0109] The prepared raw materials are put into an arc melting furnace. Due to the melting point difference, the melting needs to be carried out in three steps. First, Ta and W are put into one station for melting to obtain a W-Ta alloy, then V grains are put in for melting to obtain a W-Ta-V alloy, and finally, it is melted with Fe, Cr, and Ti raw materials to obtain the sample.

[0110] The temperature during melting is 3500 °C, the vacuum is pumped to 5×10 -3 Pa, and then argon with a purity of 99.999% is introduced into the vacuum chamber until the chamber pressure is -0.05 MPa. The raw materials are arc melted. The alloy ingot at the station is kept for 4 minutes after being completely melted, and then the alloy ingot is turned over with a turning rod and remelted. The remelting is carried out 4 times, and the melting current is kept at 18 A. The above melting process is repeated for each melting of the alloy. After melting, it is cooled with a water-cooled copper mold, and the alloy ingot is taken out to obtain the low-activation high-entropy alloy.

[0111] In the same way as in Example 1, the room-temperature mechanical properties and irradiation properties of the Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 alloy are tested. Figure 1 Shows the compression stress-strain curve of the Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 alloy (denoted as C0 in the figure) at room temperature. It can be seen that the yield strength of the alloy is 1560 MPa, and the plastic deformation amount is about 15%. At the same time, under the irradiation of high-flux He plasma with the above parameters, the thickness of the nano-villus structure generated on the surface of this alloy is 760 nm.

[0112] Comparative Example 2

[0113] Comparative Example 2 provides a low-activation high-entropy alloy Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0W 3.0 , the preparation method is slightly different from that of Comparative Example 1. The difference lies in that the vacuum is pumped to 6×10 -3 Pa, and the remaining parameters remain the same.

[0114] The results show that an oxide layer appears on the surface of the as-cast alloy. It is found by scanning electron microscopy that large agglomerated titanium oxide or titanium nitride appears in the alloy (see Figure 5 ), seriously deteriorating the alloy performance and being unfavorable for improving the comprehensive performance of the alloy.

[0115] Comparative Example 3

[0116] Comparative Example 3 provides a low-activation high-entropy alloy Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 . The preparation method of this alloy is the same as that of Comparative Example 1. The difference lies in that the melting sequence of the alloy is two-step melting. First, W, Ta, and V are melted into W-Ta-V, and then W-Ta-V is melted with elements such as Fe, Cr, and Ti. The parameters during the melting process are the same as those in Comparative Example 1.

[0117] The results show that the alloy prepared by this method will have the situation of uneven melting. Moreover, during the first-step melting process, V burns and evaporates severely, and the alloy ingot breaks after melting, and the inside is in an unpenetrated state (see Figure 4 ).

[0118] Comparative Example 4

[0119] Comparative Example 4 provides a low-activation high-entropy alloy (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ), 92 C 8 . Its preparation method is the same as that of Example 1. After the elements in the alloy react completely and the C in the matrix is saturated in solid solution, the existence of excess C will cause the alloy grains to coarsen, thereby reducing the yield strength to 1250 MPa, deteriorating the radiation resistance performance, and the thickness of the nano-villi structure generated on the alloy surface is 650 nm, which is unfavorable for improving the comprehensive performance of the alloy.

[0120] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-activation, high-strength, radiation-resistant high-entropy alloy, characterized in that: The alloy composition is (Fe 30.4 Cr 30.3 V 30.3 Ti 3.0 Ta 3.0 W 3.0 ) 100-x C x , where x is the mole percentage, 0.5≤x≤7.

2. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 1, characterized in that: The following steps are involved: S1, selecting Fe blocks, FeC alloy blocks, Cr sheets, V particles, Ti particles, W particles, and Ta particles as raw materials for batching; S2, placing the ingredients of S1 into a vacuum arc melting furnace, evacuating the furnace and introducing protective gas for arc melting; S3, after the smelting is completed, cooling is performed to obtain a high entropy alloy.

3. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: In step S2, during smelting, W particles and Ta particles are first smelted to obtain W-Ta alloy, and then V particles are added to obtain W-Ta-V alloy, and finally Fe blocks, FeC alloy blocks, Cr sheets and Ti particles are added to obtain high entropy alloy.

4. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 3, characterized in that: In step S2, each time the alloy is melted, the alloy ingot is kept for 3-5 minutes after being completely melted, and then the alloy ingot is turned over and melted again, and the melting is repeated 3-5 times, and the current is kept at 18-20A during melting.

5. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: In step S2, the smelting temperature is 3000°C to 3500°C.

6. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: In step S2, the vacuum degree during melting is 3×10 -3 Pa~5×10 -3 Pa.

7. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: In step S2, the protective gas during smelting is argon with a purity greater than 99.9%, and the atmosphere pressure is -0.04 to -0.05 MPa.

8. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: Before smelting, the raw materials are firstly polished to remove the oxide scale on the surface, and then ultrasonically cleaned and dried in anhydrous ethanol.

9. The method for preparing a low-activation, high-strength, radiation-resistant high-entropy alloy according to claim 2, characterized in that: The purity of the Fe block, FeC alloy block, Cr sheet, V particle, Ti particle, W particle and Ta particle is ≥99.95wt%, wherein the FeC alloy block contains 5wt% C.

10. Use of the low-activation, high-strength, radiation-resistant high-entropy alloy as claimed in claim 1 in structural materials and / or nuclear radiation-resistant low-activation materials.

Images