Refractory high-entropy alloy with layered heterostructure as well as preparation method and application of refractory high-entropy alloy

Abstract

The invention provides a refractory high-entropy alloy with a layered heterostructure and a preparation method and application of the refractory high-entropy alloy, and belongs to the technical field of light refractory high-entropy alloys. Low-density and high-melting-point Ti, Nb and Zr are selected as main elements, V is added to cooperate with Al to achieve the light weight effect, the content of all the elements is controlled, the alloy phase separation tendency is reduced, a single body-centered cubic disordered solid solution is kept, uneven deformation in the cold rolling deformation process is used for forming a high-dislocation-density deformation band, and the high-dislocation-density deformation band is formed; ni is added to promote a deformation belt to preferentially nucleate and grow in the recrystallization annealing process, then a layered heterostructure composed of double-peak crystal grains is obtained, and the plasticity of the alloy is improved while the alloy strength is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of light-weight refractory high-entropy alloys, and particularly relates to a refractory high-entropy alloy with a layered heterogeneous structure, a preparation method and application. BACKGROUND

[0002] The application of traditional metal structural materials in the fields of aerospace, weapon equipment and the like always faces the dual contradiction of "strengthening and toughening-lightweighting". In the prior art, the alloying for improving the strength often leads to an increase in density (for example, the density of a nickel-based high-temperature alloy is 8.5 g / cm3), and the traditional lightweight design (for example, a titanium alloy) is difficult to take into account the room-temperature mechanical properties and formability. Therefore, it is urgent to design and develop a new alloy material with lower density and high strength and toughness to meet the increasingly stringent comprehensive performance requirements of new-generation aerospace, spaceflight, navigation, nuclear power and other key high-end equipment bearing materials.

[0003] A refractory high-entropy alloy composed of multiple refractory metals has attracted widespread attention in the industry due to its high strength, high hardness, excellent radiation resistance and the like. However, the density of the alloy of this system is generally high, the intrinsic work hardening capacity of a body-centered cubic structure (BCC) is poor, and the current mainstream equal-atomic ratio design principle does not take into account the existence of intermetallic compounds, which leads to the fact that most of the current refractory high-entropy alloys are brittle or rapidly strain-softened at room temperature, greatly limiting the engineering application prospect of the refractory high-entropy alloy. Therefore, how to further reduce the density of the refractory high-entropy alloy and improve its plasticity has become a major challenge faced by the current refractory high-entropy alloy. SUMMARY

[0004] The application aims to provide a refractory high-entropy alloy with a layered heterogeneous structure, a preparation method and application. The refractory high-entropy alloy provided by the application has low density and high elongation.

[0005] In order to achieve the above application purposes, the application provides the following technical solutions: The application provides a refractory high-entropy alloy with a layered heterogeneous structure, and the chemical formula of the refractory high-entropy alloy with a layered heterogeneous structure is Ti a Nb b Zr c V d Al e Ni f , wherein 25.0 at%≤a≤40.0 at%, 20.0 at%≤b≤30.0 at%, 25.0 at%≤c≤40.0 at%, 4 at%≤d≤14.0 at%, 0 at%≤e≤7 at%, 0 at%<f≤2 at% and a+b+c+d+e+f=100%; The preparation method of the refractory high-entropy alloy with a layered heterogeneous structure comprises the following steps: (1) alloy raw materials are melted and cast to obtain alloy ingots; (2) the alloy ingots obtained in the step (1) are subjected to homogenization treatment to obtain homogenization treated alloys; (3) the homogenization treated alloys obtained in the step (2) are subjected to cold rolling deformation to obtain rolled alloys; (4) the rolled alloys obtained in the step (3) are subjected to recrystallization annealing treatment to obtain refractory high-entropy alloys with layered heterogeneous structures.

[0006] Preferably, the current for melting in the step (1) is 400-550 A.

[0007] Preferably, the temperature for homogenization treatment in the step (2) is 1100-1200 DEG C, and the time for homogenization treatment is 1-2 h.

[0008] Preferably, the temperature for homogenization treatment is 1150-1200 DEG C, and the time for homogenization treatment is 1.5-2 h.

[0009] Preferably, the rolling speed for cold rolling deformation in the step (3) is 0.1-0.3 m / s, the total reduction for cold rolling deformation is greater than or equal to 80%, and the single reduction for cold rolling deformation is 1-3%.

[0010] Preferably, the rolling speed for cold rolling deformation is 0.15-0.25 m / s, the total reduction for cold rolling deformation is 80-90%, and the single reduction for cold rolling deformation is 2-3%.

[0011] Preferably, the rolling speed for cold rolling deformation is 0.2 m / s, and the single reduction for cold rolling deformation is 2.5%.

[0012] Preferably, the temperature for recrystallization annealing treatment in the step (4) is 800-850 DEG C, and the time for recrystallization annealing treatment is 0.5-1.5 h.

[0013] Preferably, the temperature for recrystallization annealing treatment is 800-850 DEG C, and the time for recrystallization annealing treatment is 1 h.

[0014] The application also provides application of the refractory high-entropy alloy with layered heterogeneous structure in aviation, aerospace, navigation, nuclear power and weapon equipment.

[0015] The application provides a refractory high-entropy alloy with layered heterogeneous structure, and the chemical formula of the refractory high-entropy alloy with layered heterogeneous structure is Ti a Nb b Zr c V d Al e Nif Wherein, 25.0 at%≤a≤40.0 at%, 20.0 at%≤b≤30.0 at%, 25.0 at%≤c≤40.0 at%, 4 at%≤d≤14.0 at%, 0 at%≤e≤7 at%, 0 at%<f≤2 at% and a+b+c+d+e+f=100%; the preparation method of the refractory high-entropy alloy with layered heterogeneous structure comprises the following steps: (1) casting after melting the alloy raw material to obtain an alloy ingot; (2) homogenizing the alloy ingot obtained in step (1) to obtain a homogenized alloy; (3) cold rolling the homogenized alloy obtained in step (2) to obtain a rolled alloy; (4) recrystallization annealing the rolled alloy obtained in step (3) to obtain a refractory high-entropy alloy with layered heterogeneous structure. The present application selects Ti, Nb and Zr with low density and high melting point as main elements, adds V to cooperate with Al to achieve lightweight effect, controls the content of each element to reduce the tendency of phase separation, maintains a single BCC disordered solid solution, forms a high dislocation density deformation band during the uneven deformation in the cold rolling process, adds Ni to promote the preferential nucleation and growth of the deformation band during the recrystallization annealing process, and then obtains a layered heterogeneous structure organization composed of bimodal grains, which improves the plasticity while ensuring the strength of the alloy. The results of the examples show that the density of the refractory high-entropy alloy provided by the present application is 6.55 g / cm 3 Hereinafter, the yield strength is above 1000 MPa, the tensile strength is above 1020 MPa, the elongation at break is above 23%, and the highest can reach 45%. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The XRD pattern of the refractory high-entropy alloy with layered heterogeneous structure in Examples 1-5; Figure 2 The metallographic photo of the refractory high-entropy alloy with layered heterogeneous structure in Example 1; Figure 3 The metallographic photo of the refractory high-entropy alloy with layered heterogeneous structure in Example 2; Figure 4 The metallographic photo of the refractory high-entropy alloy with layered heterogeneous structure in Example 3; Figure 5 The metallographic photo of the refractory high-entropy alloy with layered heterogeneous structure in Example 4; Figure 6 The metallographic photo of the refractory high-entropy alloy with layered heterogeneous structure in Example 5; Figure 7 The tensile engineering stress-engineering strain curve diagram of the refractory high-entropy alloy with layered heterogeneous structure in Examples 1-5. DETAILED DESCRIPTION

[0017] The present application provides a refractory high-entropy alloy with a layered heterostructure, the chemical formula of the refractory high-entropy alloy with a layered heterostructure is Ti a Nb b Zr c V d Al e Ni f , wherein 25.0at%≤a≤40.0at%, 20.0at%≤b≤30.0at%, 25.0at%≤c≤40.0at%, 4at%≤d≤14.0at%, 0at%≤e≤7at%, 0at%<f≤2at% and a+b+c+d+e+f=100%; The preparation method of the refractory high-entropy alloy with a layered heterostructure comprises the following steps: (1) melting and casting the alloy raw material to obtain an alloy ingot; (2) homogenizing the alloy ingot obtained in the step (1) to obtain a homogenized alloy; (3) cold rolling the homogenized alloy obtained in the step (2) to obtain a rolled alloy; (4) recrystallization annealing the rolled alloy obtained in the step (3) to obtain a refractory high-entropy alloy with a layered heterostructure.

[0018] The present application provides a refractory high-entropy alloy with a layered heterostructure, the chemical formula of the refractory high-entropy alloy with a layered heterostructure is Ti a Nb b Zr c V d Al e Ni f .

[0019] In the present application, 25.0at%≤a≤40.0at%. As an embodiment, the a can be specifically 25at%, 26at%, 27at%, 28at%, 29at%, 30at%, 31at%, 32at%, 33at%, 34at%, 35at%, 36at%, 37at%, 38at%, 39at% or 40at%. In the present application, the density of Ti is 4.5g / cm 3 , which is significantly lower than that of traditional refractory metals (such as 19.3g / cm 3 of W, 16.6g / cm 3 of Ta), providing a lightweight basis for the alloy, and the addition of Ti can improve the intrinsic plasticity of the alloy, but the addition of Ti will reduce the BCC stability of the matrix, therefore, the content of Ti is controlled in the above range, which ensures the lightweight of the alloy and the phase stability of the alloy.

[0020] In the present application, the 20.0 at%≤b≤30.0 at%. As an embodiment, the b can be specifically 20 at%, 21 at%, 22 at%, 23 at%, 24 at%, 25 at%, 26 at%, 27 at%, 28 at%, 29 at% or 30 at%.

[0021] In the present application, the 25.0 at%≤c≤40.0 at%. As an embodiment, the c can be specifically 25 at%, 26 at%, 27 at%, 28 at%, 29 at%, 30 at%, 31 at%, 32 at%, 33 at%, 34 at%, 35 at%, 36 at%, 37 at%, 38 at%, 39 at% or 40 at%.

[0022] In the present application, Zr and Nb are important elements for forming intermetallic compounds, Zr and Nb can cause serious lattice distortion in refractory high-entropy alloys, and have solid solution strengthening effect, and both are BCC stable elements, which can effectively inhibit the phase transition and grain growth caused by Ti, improve the heat treatment stability of the alloy, and the mixing enthalpy between Zr and Nb is positive, compared with adding one of the elements alone, the synergistic addition of the two is beneficial to the uniform distribution of elements in the alloy, avoiding brittle fracture caused by local element enrichment, but the density of Zr and Nb is high, therefore, the content of Zr and Nb in the present application is controlled in the above range, which not only ensures the lightweight of the alloy, but also ensures the mechanical properties of the alloy.

[0023] In the present application, the 4at%≤d≤14.0at%. As an embodiment, the d can be specifically 4at%, 5at%, 6at%, 7at%, 8at%, 9at%, 10at%, 11at%, 12at%, 13at% or 14at%. In the present application, the density of V is lower than that of Zr and Nb, the addition of V can play a role in reducing the density of the alloy, and V is a BCC phase stabilizing element, the addition of V will not cause a large phase separation phenomenon like Al, by controlling the content of V, a part of V is added to replace Al to synergistically achieve the effect of lightweight, therefore, the content of V in the present application is controlled in the above range, which not only ensures the lightweight of the alloy, but also ensures the phase stability of the alloy.

[0024] In the present application, the 0at%≤e≤7at%. As an embodiment, the e can be specifically 0at%, 1at%, 2at%, 3at%, 4at%, 5at%, 6at% or 7at%. In the present application, there is a relatively negative mixing enthalpy between the Al element and the Zr element, the atomic size is relatively small, much smaller than other refractory elements such as Zr, and after adding Al, there is often a large atomic size mismatch in the alloy system, thereby causing the formation of second phase and phase separation, which can improve the room temperature strength of the alloy to some extent, but also seriously affects the plasticity of the alloy, therefore, the content of Al is controlled in the above range, which ensures the strength of the alloy and improves the plasticity of the alloy.

[0025] In the present application, the 0at%≤f≤2at%. As an embodiment, the f can be specifically 1at% or 2at%. In the present application, adding a small amount of Ni significantly reduces the grain recrystallization energy barrier near the rolling deformation zone, promotes the preferential nucleation and growth of the deformation zone during recrystallization, but the mixing enthalpy of Ni and Zr is negative, and excessive Ni will cause the precipitation of a brittle second phase that seriously deteriorates the plasticity, and its density is relatively high, therefore, the content of Ni is controlled in the above range, which ensures the lightweight of the alloy and the plasticity of the alloy.

[0026] In the present application, the preparation method of the refractory high-entropy alloy with a layered heterogeneous structure comprises the following steps: (1) The alloy raw material is melted and cast to obtain an alloy ingot; (2) The alloy ingot obtained in the step (1) is subjected to homogenization treatment to obtain a homogenization treated alloy; (3) The homogenization treated alloy obtained in the step (2) is subjected to cold rolling deformation to obtain a rolled alloy; (4) The rolled alloy obtained in the step (3) is subjected to recrystallization annealing treatment to obtain a refractory high-entropy alloy with a layered heterogeneous structure.

[0027] In the present application, the alloy raw material is melted and cast to obtain an alloy ingot.

[0028] In the present application, the alloy raw material preferably comprises Ti particles, Nb particles, Zr particles, V particles and Ni particles, and when the content of Al is not 0, it also preferably comprises Al particles. The present application does not have special limitations on the particle size of the alloy raw material, and commercially available products known to those skilled in the art can be used.

[0029] In the present application, the purity of the alloy raw material is preferably ≥99.9%.

[0030] The application does not have special limitation on the amount of the Ti particles, Nb particles, Zr particles, V particles and Ni particles, which can be determined according to the content of each element in the product.

[0031] When the Al content is not 0, the application preferably takes 5 at% of Al particles according to the Al content in the product. Because the melting point of Al is lower, and the boiling point of Al is close to the melting point of Nb, 5 at% of Al particles are taken more.

[0032] In the application, the alloy raw material is preferably polished with sandpaper, cleaned with anhydrous ethanol by ultrasonic wave and dried in sequence before use.

[0033] The application does not have special limitation on the operation of sandpaper polishing, anhydrous ethanol ultrasonic cleaning and drying, which can remove the oxide skin and stains on the surface of the alloy raw material and dry to constant weight by using the technical solution well known to those skilled in the art.

[0034] As an embodiment, the melting is performed in a vacuum arc melting furnace or a vacuum induction melting furnace. The application does not have special limitation on the model of the vacuum arc melting furnace or the vacuum induction melting furnace, which can be a commercially available device well known to those skilled in the art.

[0035] In the application, when the Al content is not 0, the Al particles and V particles are preferably placed at the bottom of the crucible, the Ti particles and Ni particles are preferably placed above the Al particles and V particles, and the Zr particles and Nb particles are preferably placed above the Ti particles and Ni particles; when the Al content is 0, the V particles are preferably placed at the bottom of the crucible, the Ti particles and Ni particles are preferably placed above the V particles, and the Zr particles and Nb particles are preferably placed above the Ti particles and Ni particles. The application places the Al particles and V particles with lower melting point at the bottom of the crucible, and places the Zr particles and Nb particles with higher melting point at the uppermost part, which is more conducive to the melting of the alloy raw material.

[0036] The application preferably evacuates the melting furnace to 2×10 -3 ~3×10 -3 Pa, fills high-purity argon (purity ≥ 99.99%) to a vacuum degree of 0.02-0.05 MPa (i.e. primary gas absorption), and then repeats the gas absorption for 1-3 times before melting. The application performs gas absorption and controls the number of times of gas absorption, which can further reduce the influence of oxygen on the alloy.

[0037] In the application, the melting is preferably performed in a high-purity argon atmosphere; and the pressure of the argon is preferably 0.02-0.05 MPa.

[0038] In the present application, the number of melting is preferably 4-6, more preferably 5; the ingot is preferably turned over 180° after each melting for the next melting; the current of single melting is preferably 400-550 A; the time of single melting is preferably 2-4 min. As an embodiment, the current of single melting can be specifically 400 A, 410 A, 420 A, 430 A, 440 A, 450 A, 460 A, 470 A, 480 A, 490 A, 500 A, 510 A, 520 A, 530 A, 540 A or 550 A; the time of single melting can be specifically 2 min, 3 min or 4 min. The present application controls the current, time and number of melting within the above range, which can make the raw materials fully melt and mix uniformly.

[0039] The present application does not have special limitation on the operation of casting, and the technical solution of casting known to those skilled in the art can be used.

[0040] The present application does not have special limitation on the shape and size of the alloy ingot, which can be selected according to actual needs. As an embodiment, the alloy ingot can be specifically alloy bar.

[0041] After obtaining the alloy ingot, the present application performs homogenization treatment on the alloy ingot to obtain a homogenization treatment alloy.

[0042] In the present application, the temperature of homogenization treatment is preferably 1100-1200℃; the time of homogenization treatment is preferably 1-2 h. As an embodiment, the temperature of homogenization treatment can be specifically 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃ or 1200℃; the time of homogenization treatment can be specifically 1 h, 1.5 h or 2 h. The present application controls the temperature and time of homogenization treatment within the above range, which can further improve the uniformity of the alloy.

[0043] In the present application, the homogenization treatment is preferably performed in air, vacuum or protective atmosphere.

[0044] The present application does not have special limitation on the vacuum degree of the vacuum, and the vacuum condition known to those skilled in the art can be used.

[0045] The present application does not have special limitation on the type of protective atmosphere, and the protective atmosphere known to those skilled in the art can be used.

[0046] The present application preferably puts the alloy ingot into a quartz glass tube, then uses hydrogen flame to seal the tube, and then performs homogenization treatment.

[0047] After the homogenization treatment is completed, the product of the homogenization treatment is preferably subjected to water quenching and polishing in sequence to obtain the homogenization treated alloy.

[0048] The application does not have special limitations on the operation of water quenching, and the water quenching technology known to those skilled in the art can be used to quench to room temperature.

[0049] The application does not have special limitations on the operation of polishing, and the polishing technology known to those skilled in the art can be used to polish the surface layer of the alloy.

[0050] After obtaining the homogenization treated alloy, the application subjects the homogenization treated alloy to cold rolling deformation to obtain the rolled alloy.

[0051] In the application, the temperature of the cold rolling deformation is preferably room temperature; the rolling speed of the cold rolling deformation is preferably 0.1-0.3 m / s; the total reduction of the cold rolling deformation is preferably ≥80%; and the single reduction of the cold rolling deformation is preferably 1-3%. As an embodiment, the rolling speed of the cold rolling deformation can be specifically 0.1 m / s, 0.15 m / s, 0.2 m / s, 0.25 m / s or 0.3 m / s; the total reduction of the cold rolling deformation can be specifically 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90%; and the single reduction of the cold rolling deformation can be specifically 1%, 2% or 3%. The application utilizes the inhomogeneous deformation during the cold rolling deformation to form a high dislocation density deformation zone, and in the subsequent recrystallization annealing process, the Ni promotes the preferential nucleation and growth of the deformation zone, thereby obtaining a layered heterogeneous structure organization composed of bimodal grains, and by controlling the parameters of the cold rolling deformation, the plasticity of the alloy is further improved while the strength of the alloy is ensured.

[0052] After obtaining the rolled alloy, the application subjects the rolled alloy to recrystallization annealing treatment to obtain a refractory high-entropy alloy with a layered heterogeneous structure.

[0053] In the application, the temperature of the recrystallization annealing treatment is preferably 800-850℃; the time of the recrystallization annealing treatment is preferably 0.5-1.5 h; and the recrystallization annealing treatment is preferably carried out under vacuum conditions. As an embodiment, the temperature of the recrystallization annealing treatment can be specifically 800℃, 810℃, 820℃, 830℃, 840℃ or 850℃; and the time of the recrystallization annealing treatment can be specifically 0.5 h, 1 h or 1.5 h. The application does not have special limitations on the vacuum degree of the vacuum, and the vacuum conditions known to those skilled in the art can be used.

[0054] The application preferably places the rolled alloy into a quartz glass tube, then uses a hydrogen gas flame to seal the tube, and then performs recrystallization annealing treatment.

[0055] After the recrystallization annealing treatment is completed, the product of the recrystallization annealing treatment is preferably water quenched to obtain a refractory high-entropy alloy with a layered heterogeneous structure.

[0056] The operation of the water quenching is not particularly limited in the present application, and the water quenching can be performed to room temperature by using a water quenching technical solution known to those skilled in the art.

[0057] The conventional light-weight refractory high-entropy alloy in the prior art is mainly alloyed by a light-weight element Al, which on the one hand plays a role in lightening through the low-density characteristics, and on the other hand reduces the BCC stable region of the matrix, so that the second phase separation is achieved through heat treatment. Although the strength can be improved, it is a measure of sacrificing plasticity to improve strength. The present application does not use the conventional high-lightweight element alloying method, and the Al content is controlled to maintain the BCC structure of the matrix, and the phase separation phenomenon is limited. However, the biggest problem brought by low Al is that the degree of lightening is insufficient and the mechanical properties are insufficient. In view of this problem, the present application forms a special structure by optimizing the alloying elements and the corresponding heat treatment process. This structure is a layered heterogeneous structure composed of bimodal grains. The strength is provided by back stress strengthening, and the plasticity is improved by using the layered structure grain boundary as a dislocation source to improve the dislocation multiplication capacity. Thus, the alloy has high strength and high plasticity at the same time, and the process is simple and controllable.

[0058] The present application selects Ti, Zr and Nb with low density and high melting point as main elements, and adds V to assist Al to play a lightening role. Compared with the existing light-weight refractory high-entropy alloy, the tendency of phase separation is lower, and the alloy can maintain a single BCC disordered solid solution. The layered heterogeneous structure is creatively introduced into the light-weight refractory high-entropy alloy. The high dislocation density deformation band is formed by inhomogeneous deformation in the cold rolling deformation process. The deformation band is preferentially nucleated and grown in the recrystallization process by adding Ni, and then the layered heterogeneous structure composed of bimodal grains is obtained, solving the imbalance between strength and plasticity of the conventional phase separation strategy. The alloy provided by the present application not only has a lower density, but also has excellent mechanical properties. The alloy exhibits good tensile plasticity at room temperature, the yield strength of the alloy at room temperature is more than 1000 MPa, and the highest elongation at break can reach 45%, realizing the matching of strength and plasticity of the light-weight refractory high-entropy alloy. At the same time, it is beneficial to subsequent processing and deformation treatment, and can realize large-size preparation.

[0059] The present application also provides the application of the refractory high-entropy alloy with the layered heterogeneous structure in aviation, aerospace, navigation, nuclear power and weapon equipment.

[0060] The operation of the application is not particularly limited in the present application, and the application can be performed by using an application technical solution known to those skilled in the art.

[0061] The technical solutions in the present application will be clearly and completely described below with reference to the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0062] Embodiment 1 A refractory high-entropy alloy with a layered heterostructure, the chemical formula of which is Ti 25 Nb 30 Zr 40 V4Ni1; The preparation method of the refractory high-entropy alloy with a layered heterostructure is as follows: (1) according to the alloy ratio, Ti particles with a purity of 99.9%, Ni particles and Nb particles, Zr particles and V particles with a purity of 99.95% are selected, and then are sequentially polished on the surface by using 120#, 320# and 600# SiC sandpaper, and then are ultrasonically cleaned by using anhydrous ethanol for 10 min, and are dried at 50℃, and then the treated alloy raw materials are placed into a vacuum arc melting furnace, the V particles are at the bottom, the Ti particles and the Ni particles are in the middle, and the Nb particles and the Zr particles are at the top, the vacuum degree of the melting furnace is extracted to 3×10 -3 Pa, high-purity argon (purity 99.99%) is filled to control the vacuum degree at 0.02 MPa (regarded as the first gas absorption), after 3 times of gas absorption, high-purity argon (purity 99.99%) is filled to 0.02 MPa, and then melting is performed, the single-time melting time is 3 min, the melting current is 400 A, the repeated melting is performed for 5 times, and finally the molten metal liquid is cast into a mold to obtain alloy rod materials; (2) the alloy rod materials obtained in step (1) are placed into a quartz glass tube, the vacuum degree of the glass tube is extracted to 2×10 3 Pa, hydrogen flame is used for tube sealing, homogenization treatment is performed at 1200℃ for 2 h, water quenching is performed to cool to room temperature, and the surface 0.3 mm in thickness is polished off to obtain homogenization treated alloy; (3) the homogenization treated alloy obtained in step (2) is subjected to cold rolling deformation, the temperature of the cold rolling deformation is room temperature, the single-time reduction is 2.5%, the rolling rate is 0.2 m / s, and the total reduction is 90% to obtain rolled alloy plate materials; (4) the rolled alloy plate materials obtained in step (3) are placed into a quartz glass tube, the vacuum degree of the glass tube is extracted to 2×10 3 Pa, hydrogen flame is used for tube sealing, recrystallization annealing treatment is performed at 800℃ for 1 h, water quenching is performed to cool to room temperature, and the refractory high-entropy alloy with a layered heterostructure is obtained.

[0063] Embodiment 2 A refractory high-entropy alloy with a layered heterostructure and the chemical formula Ti 40 Nb 20 Zr 25 V 14 Ni1; The preparation method of the refractory high-entropy alloy with layered heterostructure is the same as in Example 1.

[0064] Example 3 A refractory high-entropy alloy with a layered heterostructure and the chemical formula Ti 35 Nb 25 Zr 25 V 10 Al4Ni1; The preparation method of the refractory high entropy alloy with layered heterostructure is as follows: (1) According to the alloy ratio, select Ti particles and Ni particles with a purity of 99.9% and Nb particles, Zr particles and V particles with a purity of 99.95%. Weigh out 5 at% Al particles according to the Al content in the alloy ratio. Use 120#, 320# and 600# SiC sandpaper to polish the surface in sequence. Then use anhydrous ethanol to perform ultrasonic cleaning for 10 min. Dry at 50℃. Put the treated alloy raw materials into a vacuum arc melting furnace. Al particles and V particles are at the bottom, Ti particles and Ni particles are in the middle, and Nb particles and Zr particles are at the top. Evacuate the furnace to 3×10 -3 Pa, high-purity argon gas (99.99% purity) is introduced to control the vacuum at 0.02 MPa (considered as one gas intake). After three gas intakes, high-purity argon gas (99.99% purity) is introduced to a pressure of 0.02 MPa before melting. The melting time for each melting is 3 minutes, and the melting current is 400 A. The melting is repeated 5 times by flipping. Finally, the molten metal is poured into a mold to obtain alloy rods. (2) Place the alloy rod obtained in step (1) into a quartz glass tube and evacuate the vacuum level of the glass tube to 2×10⁻⁶. 3 Below Pa, the tube is sealed with a hydrogen flame, homogenized at 1200℃ for 2 hours, cooled to room temperature by water quenching, and the surface thickness of 0.3 mm is removed by grinding to obtain the homogenized alloy. (3) The homogenized alloy obtained in step (2) is subjected to cold rolling deformation. The temperature of cold rolling deformation is room temperature, the single reduction is 2.5%, the rolling speed is 0.2m / s, and the total reduction is 90%, to obtain the rolled alloy sheet. (4) Place the rolled alloy sheet obtained in step (3) into a quartz glass tube and evacuate the vacuum level of the glass tube to 2×10⁻⁶. 3 Below Pa, the tube was sealed with a hydrogen flame, recrystallized and annealed at 800℃ for 1 hour, and then water-quenched to room temperature to obtain a refractory high-entropy alloy with a layered heterostructure.

[0065] Example 4 A refractory high-entropy alloy with a layered heterostructure, its chemical formula being Ti 35 Nb 25 Zr 25 V6Al7Ni2; The preparation method of the refractory high-entropy alloy with layered heterostructure is the same as in Example 3.

[0066] Example 5 A refractory high-entropy alloy with a layered heterostructure, its chemical formula being Ti 35 Nb 25 Zr 25 V6Al7Ni2; The preparation method of the refractory high entropy alloy with layered heterostructure is as follows: (1) According to the alloy ratio, select Ti particles and Ni particles with a purity of 99.9% and Nb particles, Zr particles and V particles with a purity of 99.95%. Weigh out 5 at% Al particles according to the Al content in the alloy ratio. Use 120#, 320# and 600# SiC sandpaper to polish the surface in sequence. Then use anhydrous ethanol to perform ultrasonic cleaning for 10 min. Dry at 50℃. Put the treated alloy raw materials into a vacuum arc melting furnace. Al particles and V particles are at the bottom, Ti particles and Ni particles are in the middle, and Nb particles and Zr particles are at the top. Evacuate the furnace to 3×10 -3 Pa, high-purity argon gas (99.99% purity) is introduced to control the vacuum at 0.02 MPa (considered as one gas intake). After three gas intakes, high-purity argon gas (99.99% purity) is introduced to a pressure of 0.02 MPa before melting. The melting time for each melting is 3 minutes, and the melting current is 400 A. The melting is repeated 5 times by flipping. Finally, the molten metal is poured into a mold to obtain alloy rods. (2) Place the alloy rod obtained in step (1) into a quartz glass tube and evacuate the vacuum level of the glass tube to 2×10⁻⁶. 3 Below Pa, the tube is sealed with a hydrogen flame, homogenized at 1200℃ for 2 hours, cooled to room temperature by water quenching, and the surface thickness of 0.3 mm is removed by grinding to obtain the homogenized alloy. (3) The homogenized alloy obtained in step (2) is subjected to cold rolling deformation. The temperature of cold rolling deformation is room temperature, the single reduction is 2.5%, the rolling speed is 0.2m / s, and the total reduction is 80%, to obtain the rolled alloy sheet. (4) Place the rolled alloy sheet obtained in step (3) into a quartz glass tube and evacuate the vacuum level of the glass tube to 2×10⁻⁶. 3Pa and below, using a hydrogen flame to seal the tube, recrystallization annealing treatment at 850℃ for 1h, water quenching to room temperature, to obtain a refractory high-entropy alloy with a layered heterogeneous structure.

[0067] The XRD patterns of the refractory high-entropy alloys with layered heterogeneous structures in Examples 1-5 are shown in Figure 1 From Figure 1 it can be seen that the alloys in the examples are all single-phase BCC structures.

[0068] The metallographic photos of the refractory high-entropy alloys with layered heterogeneous structures in Examples 1-5 are shown in Figures 2-6 From Figures 2-6 it can be seen that the coarse grains, fine grains and rolling deformation bands of the alloys are distributed in layers.

[0069] The tensile engineering stress-engineering strain curve graphs of the refractory high-entropy alloys with layered heterogeneous structures in Examples 1-5 are shown in Figure 7 From Figure 7 it can be seen that the yield strength of the alloys is more than 1000MPa, and the highest elongation at break can reach 45%.

[0070] Hardness testing was performed using a HVS-1000A Vickers hardness tester with a load of 1Kg, and the average value was taken after hitting 5 points.

[0071] Density testing was performed using the Archimedes drainage method, and the dry weight of the alloy entity was measured using an MSA324S-000-DU electronic balance, then the alloy entity was completely immersed in distilled water, and its actual volume was calculated to calculate its actual density.

[0072] According to the national standard "Metallic Materials Tensile Test Part 1: Room Temperature Test Method" (GB / T 228.1-2021), quasi-static tensile testing of the alloy was performed using an electronic universal testing machine, and the average value of the yield strength, tensile strength and elongation at break of 5 identically treated samples was taken.

[0073] The hardness, density, yield strength, tensile strength and elongation at break of the refractory high-entropy alloys with layered heterogeneous structures in Examples 1-5 are shown in Table 1.

[0074] Table 1 Hardness, density, yield strength, tensile strength and elongation at break of the refractory high-entropy alloys with layered heterogeneous structures in Examples 1-5

[0075] From Table 1, it can be seen that the high-entropy alloy provided by the present application has a lower density, a higher hardness, and at the same time has a higher yield strength, tensile strength and elongation at break.

[0076] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A refractory high-entropy alloy having a layered heterostructure, characterized in that, The chemical formula of the refractory high-entropy alloy with a layered heterostructure is Ti a Nb b Zr c V d Al e Ni f wherein 25.0 at%≤a≤40.0 at%, 20.0 at%≤b≤30.0 at%, 25.0 at%≤c≤40.0 at%, 4 at%≤d≤14.0 at%, 0 at%≤e≤7 at%, 0 at%<f≤2 at% and a+b+c+d+e+f=100%. The preparation method of the refractory high-entropy alloy with layered heterostructure comprises the following steps: (1) alloy raw materials are melted and cast to obtain an alloy ingot; (2) the alloy ingot obtained in step (1) is subjected to homogenization treatment to obtain a homogenization treated alloy; (3) the homogenization treated alloy obtained in step (2) is subjected to cold rolling deformation to obtain a rolled alloy; (4) the rolled alloy obtained in step (3) is subjected to recrystallization annealing treatment to obtain a refractory high-entropy alloy with layered heterostructure.

2. The refractory high-entropy alloy with layered heterostructure according to claim 1, characterized in that, The current for melting in step (1) is 400-550 A.

3. The refractory high-entropy alloy with layered heterostructure according to claim 1, characterized in that, The temperature for homogenization treatment in step (2) is 1100-1200℃, and the homogenization treatment time is 1-2 h.

4. The refractory high-entropy alloy with layered heterostructure according to claim 3, characterized in that, The temperature for homogenization treatment is 1150-1200℃, and the homogenization treatment time is 1.5-2 h.

5. The refractory high-entropy alloy with layered heterostructure according to claim 1, characterized in that, The rolling speed for cold rolling deformation in step (3) is 0.1-0.3 m / s, the total reduction of cold rolling deformation is ≥80%, and the single reduction of cold rolling deformation is 1-3%.

6. The refractory high-entropy alloy with layered heterostructure according to claim 5, characterized in that, The rolling speed for cold rolling deformation is 0.15-0.25 m / s, the total reduction of cold rolling deformation is 80-90%, and the single reduction of cold rolling deformation is 2-3%.

7. The refractory high-entropy alloy with layered heterostructure according to claim 6, characterized in that, The rolling speed for cold rolling deformation is 0.2 m / s, and the single reduction of cold rolling deformation is 2.5%.

8. The refractory high-entropy alloy with layered heterostructure according to claim 1, characterized in that, The temperature for recrystallization annealing treatment in step (4) is 800-850℃, and the recrystallization annealing treatment time is 0.5-1.5 h.

9. The refractory high-entropy alloy with layered heterostructure according to claim 8, characterized in that, The temperature for recrystallization annealing treatment is 800-850℃, and the recrystallization annealing treatment time is 1 h.

10. The refractory high-entropy alloy with layered heterostructure according to any one of claims 1-9 is applied in aviation, aerospace, navigation, nuclear power and weapon equipment.

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