Lightweight high-strength high-temperature-resistant high-entropy alloy as well as preparation method and application thereof

Abstract

The invention provides a light high-strength high-temperature-resistant high-entropy alloy as well as a preparation method and application thereof, and relates to the technical field of high-temperature alloys. The light-weight high-strength high-temperature-resistant high-entropy alloy is composed of seven elements of Al, Cr, Mo, Nb, Ni, Ti and V. The chemical components are AlaCrbMocNbdNieTifVg, 10 < = a < = 15, 10 < = b < = 20, 5 < = c < = 10, 10 < = d < = 20, 5 < = e < = 10, 5 < = f < = 10, 30 < = g < = 40, and a + b + c + d + e + f + g = 10. The light high-strength high-temperature-resistant high-entropy alloy is prepared through raw material weighing, grinding and ultrasonic cleaning in the raw materials, vacuum degree in smelting and casting, argon adjustment, multiple times of smelting and electromagnetic stirring and solution treatment. The light high-strength high-temperature-resistant high-entropy alloy has excellent compressive strength, yield strength and hardness at room temperature and high temperature; the preparation method is simple and easy to operate, green and environment-friendly, low in cost, short in process, high in efficiency and beneficial to industrial large-scale production and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys for high-temperature use, and particularly to a lightweight and high-strength high-temperature-resistant high-entropy alloy, a preparation method thereof, and an application thereof. Background Art

[0002] At present, nickel-based superalloys are mainly used for the turbine disks of high-thrust-to-weight-ratio aeroengines. However, due to the inherent temperature-bearing limitation of the nickel-based superalloys themselves, in order to maintain high-temperature strength, a large number of high-melting-point and high-density elements (such as W, Mo, Re) need to be added, resulting in the inability to meet the urgent need of the next-generation aeroengines for lightweight and high-strength materials. In recent years, high-temperature-resistant high-entropy alloys (RHEAs) have shown potential such as low density, high strength, corrosion resistance, and high-temperature stability due to their unique multi-principal-element design concept, and have become a research hotspot for a new generation of high-performance metallic materials.

[0003] However, there are still significant technical bottlenecks in the existing high-temperature-resistant high-entropy alloy systems: on the one hand, in order to pursue high-strength and heat-resistant characteristics, most high-entropy alloys rely on high contents of heavy metal elements and are difficult to meet the lightweight requirements; on the other hand, the strengthening ability and oxidation resistance of traditional high-temperature-resistant high-entropy alloys at high temperatures (≥800 °C) are insufficient, resulting in a significant decrease in high-temperature strength and tissue stability. Therefore, under the premise of meeting the lightweight requirements, it is of great significance to develop new lightweight and high-strength high-temperature-resistant high-entropy alloys by introducing strengthening phases with high temperature-bearing capacity.

[0004] Currently, most of them are adjusted by adjusting the composition and / or heat treatment process to improve, but there are many deficiencies.

[0005] For example, Chinese Patent CN119082586A discloses a lightweight and high-strength heat-resistant high-entropy alloy and a preparation method thereof. The composition thereof contains heavy metal elements. Although it can improve the tensile strength and elongation at room temperature and high temperature, the improvement amplitude is not large, the cost of alloy elements is high, and the yield strength is also low.

[0006] The same is true for Chinese Patent CN115386780A. The addition of heavy metal elements increases the production cost, and the addition of titanium elements for lightweighting further increases the production cost. The subsequent solution aging treatment is aimed at the as-cast alloy under this composition, and its hardness and compressive strength are low.

[0007] Chinese Patent CN114277301A discloses a high-strength, high-toughness and lightweight high-entropy alloy and a preparation method thereof. Obviously, the addition of high-cost titanium elements in the composition increases the production cost. Although multiple smelting can remove impurities, the improvement of hardness and strength is not significant. The same is true for Chinese Patent CN119351848A. The addition of heavy metal elements increases the addition of titanium elements, and multiple smelting does not effectively improve the yield strength and compressive strength at room temperature and high temperature.

[0008] In addition, considering that nickel-based strengthening phases (such as γ'-Ni3Al, γ”-Ni3Nb) are still regarded as the key path to improve the temperature-bearing capacity of alloys due to their excellent coherent / semi-coherent strengthening effect and high-temperature stability, the introduction of Ni element will significantly reduce the melting point and bring great temperature-bearing limitations. Summary of the Invention

[0009] In order to solve the technical problems in the prior art that the lightweight and high-strength high-temperature-resistant high-entropy alloy contains heavy metal elements in the composition improvement, which increases the production cost of titanium element addition, and the improvement of tensile strength and elongation at room temperature and high temperature is not significant, and the improvement of hardness and compressive strength by solution aging treatment cannot meet higher requirements, and the introduction of nickel-based strengthening phase will reduce the temperature-bearing property while improving the performance; the present invention proposes a lightweight and high-strength high-temperature-resistant high-entropy alloy, a preparation method and an application that can solve the aforementioned technical problems. The technical solutions are as follows:

[0010] A lightweight and high-strength high-temperature-resistant high-entropy alloy, the chemical composition of the lightweight and high-strength high-temperature-resistant high-entropy alloy is calculated by atomic percentage as: Al a Cr b Mo c Nb d Ni e Ti f V g , where 10 ≤ a ≤ 15, 10 ≤ b ≤ 20, 5 ≤ c ≤ 10, 10 ≤ d ≤ 20, 5 ≤ e ≤ 10, 5 ≤ f ≤ 10, 30 ≤ g ≤ 40, and a + b + c + d + e + f + g = 100.

[0011] The mechanism for the selection of each component content in the present invention is as follows:

[0012] The composition design of this high-entropy alloy is based on the multi-component synergistic effect and the requirements of lightweight and high-temperature resistance. The high V content is the core of matrix strengthening and lightweighting. The density of V is 6.11 g / cm³, which is much lower than that of traditional Ni / Co-based superalloys. In addition, V has a stable BCC structure at high temperatures, providing matrix strength; certain contents of Al, Ti, and Cr can not only significantly reduce the density, but also improve the high-temperature oxidation resistance by forming a dense oxide film; Mo and Nb are the balance elements for regulating the matrix strength and plasticity. Although both have the effect of stabilizing BCC and high solution strengthening ability, when the Mo content is relatively high (>8%), it will cause serious plastic loss. When the Nb content is greater than the Mo content, it has a good ductility tendency; the introduction of Ni is on the one hand because of the excellent strengthening ability of Ni-containing strengthening phases, especially the high binding ability with Al, Ti, Nb, etc. However, the Ni content must be controlled at a relatively low level, otherwise the melting point will be greatly reduced and the high-temperature performance will be damaged.

[0013] Optionally, the melting point of the lightweight, high-strength, and high-temperature-resistant high-entropy alloy exceeds 1300 °C, and the density is 6.45 - 6.90 g / cm 3 , and the phase composition is BCC phase, Nb2NiAl phase, and α-Ti phase.

[0014] Optionally, the room-temperature strain rate of the lightweight, high-strength, and high-temperature-resistant high-entropy alloy is 0.001 s -1 , its room-temperature yield strength is 1900 - 2145 MPa, and the compressive strength is 1920 - 2190 MPa; the strain rate of the lightweight, high-strength, and high-temperature-resistant high-entropy alloy at 850 °C is 0.005 s -1 , the yield strength exceeds 1300 MPa, and the compressive strength exceeds 1400 MPa; at 1000 °C, the strain rate is 0.005 s -1 , the yield strength exceeds 720 MPa, and the compressive strength exceeds 800 MPa; the Vickers hardness value is 570 - 650 HV5.

[0015] A preparation method based on the above-mentioned lightweight, high-strength, and high-temperature-resistant high-entropy alloy. The preparation method of the lightweight, high-strength, and high-temperature-resistant high-entropy alloy includes the following steps:

[0016] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti, and V with a purity of 99.9 wt% or more according to the chemical composition of the lightweight, high-strength, and high-temperature-resistant high-entropy alloy, and perform pretreatment to obtain the processed raw materials;

[0017] S2. Melting and casting: The raw materials processed in S1 are melted multiple times by a vacuum melting process, and after casting, they are cooled to room temperature in the furnace to obtain alloy ingots;

[0018] S3. Ingot solution treatment: The alloy ingots in S2 are subjected to solution treatment in an argon atmosphere and cooled to room temperature with water to obtain the lightweight, high-strength, and high-temperature-resistant high-entropy alloy.

[0019] Optionally, the specific steps of S1 raw material weighing are as follows:

[0020] S101. All high-purity metal particles are carefully polished on the surface of the material by a grinding wheel or an angle grinder to remove the surface oxide film or impurity layer, and then the mass of the required raw materials is accurately weighed;

[0021] S102. The weighed raw materials are all placed in a beaker containing anhydrous ethanol for ultrasonic oscillation cleaning. The cleaning time is 3 - 5 min. After ultrasonic cleaning, they are rinsed with anhydrous ethanol and quickly dried to remove the impurities remaining on the surface.

[0022] Optionally, the specific steps of S2 melting and casting are as follows:

[0023] S201. Before melting, first pump the melting furnace to a vacuum level of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the gauge pressure in the furnace reaches -0.05 MPa.

[0024] S202. During the melting process, each alloy ingot is flipped and melted 5 - 7 times, with each time lasting for 3 - 5 minutes, and electromagnetic stirring function is used for stirring; after melting is completed, it is cooled to room temperature with the furnace to obtain alloy ingots.

[0025] Optionally, the solution treatment of the ingot is specifically as follows:

[0026] S301. Before the solution treatment, first seal the experimental sample of the alloy ingot into a quartz tube in an argon atmosphere.

[0027] S302. Put the quartz tube with the ingot sample into a box-type resistance furnace of KSI 1700X, set the heating rate at 4 - 6 °C / min, the solution temperature at 1150 - 1200 °C, and the holding time at 20 - 24 h. After reaching the time, quickly clamp it out and break the quartz tube, and the sample falls into water for cooling to obtain a lightweight, high-strength, high-temperature-resistant high-entropy alloy.

[0028] Application of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared according to the described lightweight, high-strength, high-temperature-resistant high-entropy alloy or the described preparation method in the field of high-temperature structural materials.

[0029] Technical principle of the present invention:

[0030] Through the selection of lightweight and high-temperature-stable BCC matrix elements and the introduction of strong ordering elements such as Ni, Al, Ti, etc., the present invention forms ordered strengthening phases, synergistically improves high-temperature oxidation resistance and lightweight and high-strength properties, and realizes multi-phase synergistic strengthening.

[0031] The above technical solution has at least the following beneficial effects compared with the prior art:

[0032] In the above solution, the present invention provides a lightweight, high-strength, high-temperature-resistant high-entropy alloy, its preparation method and application, which can solve the technical problems in the prior art that in the composition improvement of the lightweight, high-strength, high-temperature-resistant high-entropy alloy, the inclusion of heavy metal elements increases the production cost of titanium element addition, and the improvement of tensile strength and elongation at room temperature and high temperature is not significant, the solution aging treatment cannot meet higher requirements for the improvement of hardness and compressive strength, and the introduction of nickel-based strengthening phases will reduce the temperature resistance while improving the performance.

[0033] Through grinding and ultrasonic cleaning in raw material weighing, the present invention can remove the surface oxide film and impurities remaining on the surface.

[0034] The present invention can reduce the oxygen content and improve the compositional uniformity through the vacuum degree, argon regulation, multiple melting, and electromagnetic stirring in the melting and casting process.

[0035] Through the solution treatment of the ingot, the present invention can obtain a lightweight, high-strength, high-temperature-resistant high-entropy alloy with multi-phase synergistic strengthening.

[0036] In summary, compared with other traditional methods, the method of the present invention prepares a lightweight, high-strength, high-temperature-resistant high-entropy alloy through raw material weighing, grinding, ultrasonic cleaning, vacuum degree, argon regulation, multiple melting, electromagnetic stirring, and solution treatment of the ingot; the lightweight, high-strength, high-temperature-resistant high-entropy alloy has excellent compressive strength, yield strength, and hardness at room temperature and high temperature; this preparation method is simple, easy to operate, environmentally friendly, low-cost, short-process, and high-efficiency, which is conducive to large-scale industrial production and promotion. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1(a) is a 1kx secondary electron scanning image of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared by the preparation method of the lightweight, high-strength, high-temperature-resistant high-entropy alloy in Embodiment 1 of the present invention;

[0039] Figure 1(b) is a 5kx secondary electron scanning image of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared by the preparation method of the lightweight, high-strength, high-temperature-resistant high-entropy alloy in Embodiment 1 of the present invention;

[0040] Figure 1(c) is a 20kx secondary electron scanning image of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared by the preparation method of the lightweight, high-strength, high-temperature-resistant high-entropy alloy in Embodiment 1 of the present invention;

[0041] Figure 2 is a schematic diagram of the XRD analysis result of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared by the preparation method of the lightweight, high-strength, high-temperature-resistant high-entropy alloy in Embodiment 1 of the present invention;

[0042] Figure 3 is a schematic diagram of the compressive test stress-strain curve of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared by the preparation method of the lightweight, high-strength, high-temperature-resistant high-entropy alloy in Embodiment 1 of the present invention. Detailed Embodiments

[0043] The following describes the technical solutions in the present invention in conjunction with the drawings.

[0044] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to give examples, illustrations or explanations. Any embodiment or design solution described as an "example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of the word "example" is intended to present concepts in a specific manner. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one of the two.

[0045] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference is not emphasized, the meanings they express are the same.

[0046] In the embodiments of the present invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meanings they express are the same.

[0047] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] A lightweight and high-strength high-temperature resistant high-entropy alloy, the chemical composition of the lightweight and high-strength high-temperature resistant high-entropy alloy is calculated by atomic percentage as: Al a Cr b Mo c Nb d Ni e Ti f V g , where 10 ≤ a ≤ 15, 10 ≤ b ≤ 20, 5 ≤ c ≤ 10, 10 ≤ d ≤ 20, 5 ≤ e ≤ 10, 5 ≤ f ≤ 10, 30 ≤ g ≤ 40, and a + b + c + d + e + f + g = 100.

[0049] The mechanism for selecting the content of each component of the present invention is as follows:

[0050] The composition design of this high-entropy alloy is based on the synergistic effect of multiple elements and the requirements of lightweight and high-temperature resistance. A high V content is the core of matrix strengthening and lightweighting. The density of V is 6.11 g / cm³, which is much lower than that of traditional Ni / Co-based superalloys. In addition, V has a stable BCC structure at high temperatures, providing matrix strength. Appropriate contents of Al, Ti, and Cr can not only significantly reduce the density but also improve the high-temperature oxidation resistance by forming a dense oxide film. Mo and Nb are elements that regulate the balance between matrix strength and plasticity. Although both have the effect of stabilizing BCC and high solid-solution strengthening ability, when the Mo content is relatively high (>8%), it will cause serious loss of plasticity. When the Nb content is greater than the Mo content, it has a good ductility tendency. The introduction of Ni is on the one hand due to the excellent strengthening ability of Ni-containing strengthening phases, especially with high binding ability with Al, Ti, Nb, etc. However, the Ni content must be controlled at a relatively low level, otherwise the melting point will be greatly reduced, damaging the high-temperature performance.

[0051] Specifically, optionally, the melting point of the lightweight and high-strength high-temperature-resistant high-entropy alloy exceeds 1300 °C, and the density is 6.45 - 6.90 g / cm 3 , and the phase composition is BCC phase, Nb2NiAl phase, and α-Ti phase.

[0052] Specifically, the room-temperature strain rate of the lightweight and high-strength high-temperature-resistant high-entropy alloy is 0.001 s -1 , its room-temperature yield strength is 1900 - 2145 MPa, and the compressive strength is 1920 - 2190 MPa; the strain rate of the lightweight and high-strength high-temperature-resistant high-entropy alloy at 850 °C is 0.005 s -1 , the yield strength exceeds 1300 MPa, and the compressive strength exceeds 1400 MPa; at 1000 °C, the strain rate is 0.005 s -1 , the yield strength exceeds 720 MPa, and the compressive strength exceeds 800 MPa; the Vickers hardness value is 570 - 650 HV5.

[0053] A preparation method of the lightweight and high-strength high-temperature-resistant high-entropy alloy based on the above, the preparation method of the lightweight and high-strength high-temperature-resistant high-entropy alloy is as follows:

[0054] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti, and V with a purity of 99.9 wt% or more according to the chemical composition of the lightweight and high-strength high-temperature-resistant high-entropy alloy, and perform pretreatment to obtain the processed raw materials;

[0055] S2. Melting and casting: The raw materials processed in S1 are melted multiple times by a vacuum melting process, and after casting, they are cooled to room temperature in the furnace to obtain alloy ingots;

[0056] S3. Ingot solution treatment: The S2 alloy ingot is subjected to solution treatment in an argon atmosphere and water-cooled to room temperature to obtain a lightweight, high-strength, high-temperature-resistant high-entropy alloy.

[0057] Specifically, the weighing of the S1 raw materials is as follows:

[0058] S101. All high-purity metal particles are carefully polished on the surface of the material by a grinding wheel or an angle grinder to remove the surface oxide film or impurity layer, and then the mass of the required raw materials is accurately weighed.

[0059] S102. The weighed raw materials are all placed in a beaker containing anhydrous ethanol for ultrasonic oscillation cleaning. The cleaning time is 3 - 5 min. After ultrasonic cleaning, they are rinsed with anhydrous ethanol and quickly dried to remove the impurities remaining on the surface.

[0060] Specifically, the S2 melting and casting is as follows:

[0061] S201. Before melting, the melting furnace is first evacuated to a vacuum degree of -4 magnitude, and then high-purity argon with a purity of 99.999% is introduced until the internal pressure of the furnace reaches -0.05 MPa.

[0062] S202. During the melting process, each alloy ingot is flipped and melted 5 - 7 times, each time lasting for 3 - 5 min, and electromagnetic stirring is used for stirring; after melting is completed, it is cooled to room temperature with the furnace to obtain an alloy ingot.

[0063] Specifically, the S3 ingot solution treatment is as follows:

[0064] S301. Before solution treatment, the experimental sample of the alloy ingot is sealed in a quartz tube in an argon atmosphere.

[0065] S302. The quartz tube with the ingot sample is placed in a box-type resistance furnace of KSI 1700X. The heating rate is set at 4 - 6 °C / min, the solution temperature is 1150 - 1200 °C, and the holding time is 20 - 24 h. After reaching the time, it is quickly clamped out and the quartz tube is broken, and the sample falls into water for cooling to obtain a lightweight, high-strength, high-temperature-resistant high-entropy alloy.

[0066] Application of the lightweight, high-strength, high-temperature-resistant high-entropy alloy prepared according to the described lightweight, high-strength, high-temperature-resistant high-entropy alloy or the described preparation method in the field of high-temperature structural materials.

[0067] Example 1

[0068] The composition design of a lightweight, high-strength, high-temperature-resistant high-entropy alloy in this example is as follows:

[0069] Based on the thermodynamics and physical models of high-entropy alloy phase diagrams, the phase formation tendency of the alloy can be judged, and key data such as the phase types, precipitation temperature, and precipitation content can be obtained.

[0070] The phase formation tendency in the high-entropy alloy system can be judged based on the influence of the entropy-enthalpy coupling effect (Ω) and the atomic size difference (δ) on the phase composition of the multi-component solid solution. In order to improve the high-temperature strength of the alloy composition, an intermetallic compound phase (IM) is intentionally introduced. According to the empirical criterion reported in the literature, when 3.8% ≤ δ ≤ 6.6% and 1.1 ≤ Ω ≤ 10, the alloy composition has the formation tendency of solid solution phase and intermetallic compound phase. The calculation formulas of Ω and δ are shown in Formulas (1) and (2).

[0071] (1)

[0072] (2)

[0073] Among them, is the mixing enthalpy of the alloy, is the mixing entropy of the alloy, is the weighted average melting point of the alloy, c i is the atomic ratio of the i-th element, r i is the atomic radius of the i-th element, is the weighted average atomic radius of the alloy. and are calculated as shown in Formulas (3) and (4).

[0074] (3)

[0075] (4)

[0076] Among them, refers to the mixing enthalpy of the binary equiatomic ratio alloy, x i or x j represents the content of the i-th or j-th element, and R is the molar gas constant.

[0077] Regarding the temperature-bearing capacity of the alloy for practical applications, for traditional nickel-based superalloys, their melting points are usually around 1200 - 1300 °C, and the component melting point (T m ) of the alloy is set to be greater than 1300 °C to further improve the temperature-bearing limit. The alloy melting point is calculated based on the thermodynamic equilibrium phase diagram calculation.

[0078] For the lightweight, high-strength, and high-temperature-resistant high-entropy alloy in Example 1, the atomic percentages of its various elements are: Al: 10%, Cr: 20%, Mo: 5%, Nb: 15%, Ni: 5%, Ti: 5%, V: 40%. The calculation results of the phase formation tendency parameters and melting point of this alloy are shown in Table 2.

[0079] The preparation method comprises the following steps:

[0080] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti, and V with a purity of 99.9 wt% or more according to the chemical composition of the lightweight and high-strength high-temperature-resistant high-entropy alloy, and perform pretreatment to obtain the treated raw materials;

[0081] S101. Use a grinding wheel or angle grinder to carefully polish the surfaces of all the high-purity metal particles to remove the surface oxide film or impurity layer, and then accurately weigh the required mass of the raw materials;

[0082] S102. Place the weighed raw materials in a beaker containing absolute ethanol for ultrasonic oscillation cleaning for 3 minutes. After the ultrasonic cleaning is completed, rinse with absolute ethanol and quickly dry to remove the impurities remaining on the surface;

[0083] S2. Melting and casting: The raw materials treated in S1 are melted multiple times using a vacuum melting process, and after casting, they are cooled to room temperature in the furnace to obtain alloy ingots;

[0084] S201. Before melting, first pump the melting furnace to a vacuum degree of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the internal pressure of the furnace is -0.05 MPa;

[0085] S202. During the melting process, each alloy ingot is flipped and melted 5 times, with each time lasting for 3 minutes, and an electromagnetic stirring function is used for stirring; after melting is completed, it is cooled to room temperature in the furnace to obtain alloy ingots;

[0086] S3. Solution treatment of the ingot: The alloy ingot obtained in S2 is subjected to solution treatment in an argon atmosphere and cooled to room temperature with water to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy;

[0087] S301. Before the solution treatment, first seal the experimental sample of the alloy ingot in a quartz tube in an argon atmosphere;

[0088] S302. Place the quartz tube with the ingot sample in a box-type resistance furnace of KSL-1700X, set the heating rate to 6 °C / min to 1200 °C and hold for 24 h. After the time is reached, quickly clamp it out and break the quartz tube, and the sample falls into water for cooling to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy.

[0089] The density of the alloy measured by the Archimedes method is 6.618 ± 0.026 g / cm 3, belonging to a lightweight high-temperature resistant high-entropy alloy. Figures 1(a), 1(b), and 1(c) are respectively secondary electron morphology diagrams of the lightweight and high-strength high-temperature resistant high-entropy alloy structure under 1k times, 5k times, and 20k times magnifications; P1 - P3 are EDS element scans of different contrast phases in the scanned images, and the element distributions are shown in Table 1;

[0090] Table 1 EDS analysis results (at%)

[0091] Furthermore, Figure 2 is a schematic diagram of the as-cast XRD analysis results. Combining with energy spectrum analysis, the matrix BCC phase is between the gray dendrites, the off-white dendrite arms and the particles with the same contrast as them are Nb2NiAl phases, and the gray-black precipitates are precipitated phases of the near α-Ti type.

[0092] The compression test stress-strain curve of the lightweight and high-strength high-temperature resistant high-entropy alloy prepared in this example is as Figure 3 shown. The room temperature strain rate is 0.001 s -1 , its room temperature yield strength is 2012 MPa, and the compressive strength is 2028 MPa; the high temperature strain rate of the lightweight and high-strength high-temperature resistant high-entropy alloy is 0.005 s -1 , the yield strength at 850 °C is 1322 MPa, and the compressive strength is 1448 MPa; the yield strength at 1000 °C is 783 MPa, and the compressive strength is 825 MPa.

[0093] The Vickers hardness value of the lightweight and high-strength high-temperature resistant high-entropy alloy reaches 600 HV5.

[0094] Example 2

[0095] For the lightweight and high-strength high-temperature resistant high-entropy alloy of Example 2, the atomic percentages of its various elements are Al: 10%, Cr: 15%, Mo: 10%, Nb: 20%, Ni: 5%, Ti: 10%, V: 30%. The calculation results of the phase formation trend parameters and melting points of this alloy are shown in Table 2.

[0096] The preparation method is as follows:

[0097] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti, and V with a purity of 99.9 wt% and above according to the chemical composition of the lightweight and high-strength high-temperature resistant high-entropy alloy, and perform pretreatment to obtain the processed raw materials;

[0098] S101. Carefully polish the surfaces of all high-purity metal particles with a grinding wheel or angle grinder to remove the surface oxide film or impurity layer, and then accurately weigh the required mass of the raw materials;

[0099] S102. Place the weighed raw materials in a beaker containing absolute ethanol and perform ultrasonic oscillation cleaning for 4 minutes. After the ultrasonic cleaning is completed, rinse with absolute ethanol and quickly dry to remove the impurities remaining on the surface.

[0100] S2. Melting and casting: Subject the raw materials treated in S1 to multiple meltings using a vacuum melting process, and cool them in the furnace to room temperature after casting to obtain alloy ingots.

[0101] S201. Before melting, first pump the melting furnace to a vacuum degree of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the gauge pressure in the furnace is -0.05 MPa.

[0102] S202. During the melting process, each alloy ingot is flipped and melted 7 times, with each time lasting for 5 min, and electromagnetic stirring is used for stirring; after the melting is completed, cool it in the furnace to room temperature to obtain alloy ingots.

[0103] S3. Solution treatment of the ingot: Subject the alloy ingots in S2 to solution treatment under an argon atmosphere and cool them to room temperature with water to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy.

[0104] S301. Before the solution treatment, first seal the experimental samples of the alloy ingots in a quartz tube under an argon atmosphere.

[0105] S302. Place the quartz tube with the ingot samples in a box-type resistance furnace of KSL-1700X, set the heating rate to 5 °C / min to 1150 °C and hold for 22 h. After the time is reached, quickly clamp it out and break the quartz tube, and the samples fall into water for cooling to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy.

[0106] The alloy prepared by this method contains BCC phase, Nb2NiAl phase and α-Ti phase. The density of the alloy tested based on the Archimedes method is 6.811 ± 0.031 g / cm 3 . The room-temperature strain rate of this alloy is 0.001 s -1 , its room-temperature yield strength is 1900 MPa, and the compressive strength is 1920 MPa; the high-temperature strain rate of the lightweight and high-strength high-temperature-resistant high-entropy alloy is 0.005 s -1 , the yield strength at 850 °C is 1302 MPa, and the compressive strength is 1407 MPa; the yield strength at 1000 °C is 725 MPa, and the compressive strength is 800 MPa. The Vickers hardness of this alloy is 571 HV5.

[0107] Example 3

[0108] The light-weight, high-strength and high-temperature-resistant high-entropy alloy of Example 3 has the atomic percentages of each element as follows: Al: 15%, Cr: 10%, Mo: 5%, Nb: 15%, Ni: 10%, Ti: 5%, V: 40%. The calculation results of the phase formation tendency parameters and melting points of this alloy are shown in Table 2.

[0109] The preparation method comprises the following steps:

[0110] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti and V with a purity of 99.9 wt% or more according to the chemical composition of the light-weight, high-strength and high-temperature-resistant high-entropy alloy, and perform pretreatment to obtain the pretreated raw materials;

[0111] S101. Use a grinding wheel or angle grinder to carefully polish the surfaces of all high-purity metal particles to remove the surface oxide film or impurity layer, and then accurately weigh the required mass of raw materials;

[0112] S102. Place the weighed raw materials in a beaker containing absolute ethanol for ultrasonic oscillation cleaning for 5 minutes. After the ultrasonic cleaning is completed, rinse with absolute ethanol and quickly dry to remove the impurities remaining on the surface;

[0113] S2. Melting and casting: Subject the raw materials treated in S1 to multiple meltings using a vacuum melting process, and cool them to room temperature in the furnace after casting to obtain alloy ingots;

[0114] S201. Before melting, first pump the melting furnace to a vacuum level of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the gauge pressure in the furnace is -0.05 MPa;

[0115] S202. During the melting process, turn each alloy ingot over and melt it 7 times, with each time lasting for 4 minutes, and use the electromagnetic stirring function for stirring; after melting is completed, cool it to room temperature in the furnace to obtain alloy ingots.

[0116] S3. Solution treatment of ingots: Subject the alloy ingots in S2 to solution treatment in an argon atmosphere and cool them to room temperature in water to obtain the light-weight, high-strength and high-temperature-resistant high-entropy alloy;

[0117] S301. Before the solution treatment, first seal the experimental samples of the alloy ingots in a quartz tube in an argon atmosphere;

[0118] S302. Place the quartz tube with the ingot samples in a box-type resistance furnace of KSL-1700X, set the heating rate to 4 °C / min, heat to 1180 °C and hold for 20 h. After the time is reached, quickly clamp it out and break the quartz tube, and the samples fall into water for cooling to obtain the light-weight, high-strength and high-temperature-resistant high-entropy alloy.

[0119] The alloy samples prepared by this method are of BCC phase, Nb2NiAl phase and α-Ti phase. The density of the alloy tested based on the Archimedes method is 6.486 ± 0.027 g / cm 3 . The strain rate of the alloy at room temperature is 0.001 s -1 , its yield strength at room temperature is 2046 MPa, and its compressive strength is 2077 MPa; the strain rate of the lightweight, high-strength and high-temperature-resistant high-entropy alloy at high temperature is 0.005 s -1 , its yield strength at 850 °C is 1350 MPa, and its compressive strength is 1496 MPa; its yield strength at 1000 °C is 786 MPa, and its compressive strength is 835 MPa. The Vickers hardness of this alloy is 633 HV5.

[0120] Example 4

[0121] For the lightweight, high-strength and high-temperature-resistant high-entropy alloy of Example 4, the atomic percentages of its various elements are as follows: Al: 10%, Cr: 15%, Mo: 10%, Nb: 20%, Ni: 5%, Ti: 5%, V: 35%. The calculation results of the phase formation trend parameters and melting points of this alloy are shown in Table 2.

[0122] The preparation method is as follows:

[0123] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti and V with a purity of 99.9 wt% or more according to the chemical composition of the lightweight, high-strength and high-temperature-resistant high-entropy alloy, and perform pretreatment to obtain the processed raw materials;

[0124] S101. Use a grinding wheel or angle grinder to carefully polish the surfaces of all high-purity metal particles to remove the surface oxide film or impurity layer, and then accurately weigh the mass of the required raw materials;

[0125] S102. Place the weighed raw materials in a beaker containing absolute ethanol for ultrasonic oscillation cleaning. The cleaning time is 3 minutes. After ultrasonic cleaning, rinse with absolute ethanol and quickly dry to remove the impurities remaining on the surface;

[0126] S2. Melting and casting: Use the vacuum melting process to melt the raw materials processed in S1 multiple times, and cool them to room temperature with the furnace after casting to obtain alloy ingots;

[0127] S201. Before melting, first pump the melting furnace to a vacuum degree of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the gauge pressure in the furnace is -0.05 MPa;

[0128] S202. During the smelting process, each alloy ingot is flipped and smelted 6 times, with each time lasting for 5 minutes, and electromagnetic stirring function is used for stirring; after smelting is completed, it is cooled to room temperature in the furnace to obtain alloy ingots.

[0129] S3. Solution treatment of the ingot: The S2 alloy ingot is subjected to solution treatment under an argon atmosphere and cooled to room temperature with water to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy;

[0130] S301. Before the solution treatment, the experimental sample of the alloy ingot is sealed in a quartz tube under an argon atmosphere;

[0131] S302. The quartz tube with the ingot sample is placed in a box-type resistance furnace of KSL-1700X, and the heating rate is set to 6 °C / min to 1150 °C for heat preservation for 24 hours. After the time is reached, it is quickly clamped out and the quartz tube is broken, and the sample falls into water for cooling to obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy.

[0132] The alloy sample prepared by this method contains BCC phase, Nb2NiAl phase and α-Ti phase. The density of the alloy tested based on the Archimedes method is 6.901 ± 0.021 g / cm 3 . The room-temperature strain rate of this alloy is 0.001 s -1 , and its room-temperature yield strength is 1958 MPa, and the compressive strength is 2002 MPa; the high-temperature strain rate of the as-cast lightweight and high-strength high-temperature-resistant high-entropy alloy is 0.005 s -1 , the yield strength at 850 °C is 1310 MPa, and the compressive strength is 1433 MPa; the yield strength at 1000 °C is 755 MPa, and the compressive strength is 816 MPa. The Vickers hardness of this alloy is 589 HV5.

[0133] Example 5

[0134] For the lightweight and high-strength high-temperature-resistant high-entropy alloy of Example 5, the atomic percentages of its various elements are Al: 15%, Cr: 10%, Mo: 5%, Nb: 20%, Ni: 10%, Ti: 5%, V: 35%. The calculation results of the phase formation trend parameters and melting points of this alloy are shown in Table 2.

[0135] The preparation method is as follows:

[0136] S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti and V with a purity of 99.9 wt% and above according to the chemical composition of the lightweight and high-strength high-temperature-resistant high-entropy alloy, and carry out pretreatment to obtain the treated raw materials;

[0137] S101. All high-purity metal particles are used to carefully grind the surface of the material with a grinding wheel or an angle grinder to remove the surface oxide film or impurity layer, and then the mass of the required raw materials is accurately weighed.

[0138] S102. The weighed raw materials are all placed in a beaker containing anhydrous ethanol for ultrasonic oscillation cleaning. The cleaning time is 3 minutes. After the ultrasonic cleaning is completed, it is rinsed with anhydrous ethanol and quickly dried to remove the impurities remaining on the surface.

[0139] S2. Melting and casting: The raw materials processed in S1 are melted multiple times by a vacuum melting process, and after casting, they are cooled to room temperature in the furnace to obtain alloy ingots.

[0140] S201. Before melting, the melting furnace is first evacuated to a vacuum level of -4 magnitude, and then high-purity argon with a purity of 99.999% is introduced until the gauge pressure in the furnace is -0.05 MPa.

[0141] S202. During the melting process, each alloy ingot is flipped and melted 6 times, with each time lasting for 4 minutes, and electromagnetic stirring is used for stirring; after melting is completed, it is cooled to room temperature in the furnace to obtain alloy ingots.

[0142] S3. Solution treatment of ingots: The alloy ingots in S2 are subjected to solution treatment in an argon atmosphere and cooled to room temperature in water to obtain a lightweight and high-strength high-temperature resistant high-entropy alloy.

[0143] S301. Before solution treatment, the experimental samples of the alloy ingots are sealed in a quartz tube in an argon atmosphere.

[0144] S302. The quartz tube with the ingot samples is placed in a box-type resistance furnace of KSL-1700X, and the heating rate is set at 5 °C / min to 1200 °C and held for 20 h. After the time is reached, it is quickly clamped out and the quartz tube is broken, and the samples fall into water for cooling to obtain a lightweight and high-strength high-temperature resistant high-entropy alloy.

[0145] The alloy samples prepared by this method are of BCC phase, Nb2NiAl phase and α-Ti phase. The density of the alloy measured based on the Archimedes method is 6.612 ± 0.044 g / cm 3 . The room-temperature strain rate of this alloy is 0.001 s -1 , and its room-temperature yield strength is 2145 MPa and the compressive strength is 2190 MPa; the high-temperature strain rate of the lightweight and high-strength high-temperature resistant high-entropy alloy is 0.005 s -1 , the yield strength at 850 °C is 1372 MPa and the compressive strength is 1513 MPa; the yield strength at 1000 °C is 811 MPa and the compressive strength is 838 MPa. The Vickers hardness of this alloy is 650 HV5.

[0146] Table 2 Calculation Results of Phase Formation Trend Parameters and Melting Points of Alloys in Examples 1-5

[0147]

[0148] In the above solution, the present invention provides a lightweight and high-strength high-temperature-resistant high-entropy alloy, its preparation method and application, which can solve the technical problems in the prior art that in the composition improvement of lightweight and high-strength high-temperature-resistant high-entropy alloys, the inclusion of heavy metal elements in the composition increases the production cost of adding titanium elements, and the improvement of the tensile strength and elongation at room temperature and high temperature is not significant. The improvement of hardness and compressive strength by solution aging treatment cannot meet higher requirements, and the introduction of nickel-based strengthening phases will reduce the temperature resistance while improving the performance, etc.

[0149] Through grinding and ultrasonic cleaning in raw material weighing, the present invention can remove the surface oxide film and impurities remaining on the surface.

[0150] Through the vacuum degree, argon regulation, multiple melting and electromagnetic stirring in melting and casting, the present invention can reduce the oxygen content and improve the composition uniformity.

[0151] Through the treatment of the ingot by the solution method, the present invention can obtain a lightweight and high-strength high-temperature-resistant high-entropy alloy with multi-phase synergistic strengthening.

[0152] In summary, compared with other traditional methods, the method of the present invention prepares a lightweight and high-strength high-temperature-resistant high-entropy alloy through raw material weighing, grinding and ultrasonic cleaning therein, the vacuum degree, argon regulation, multiple melting and electromagnetic stirring in melting and casting, and ingot solution treatment; the lightweight and high-strength high-temperature-resistant high-entropy alloy has excellent compressive strength, yield strength and hardness at room temperature and high temperature; the preparation method is simple, easy to operate, environmentally friendly, low in cost, short in process and high in efficiency, which is conducive to large-scale industrial production and promotion.

[0153] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Among them, A and B can be singular or plural. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after, but it may also represent an "and / or" relationship, which can be specifically understood with reference to the context before and after.

[0154] In the present invention, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or a similar expression means any combination of these items, including any combination of single item(s) or plural item(s). For example, at least one of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, and c can be single or plural.

[0155] It should be understood that in various embodiments of the present invention, the magnitudes of the serial numbers of the above processes do not imply the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0156] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, and all of them should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A lightweight and high-strength high-temperature resistant high-entropy alloy, characterized in that, The chemical composition of the lightweight and high-strength high-temperature resistant high-entropy alloy is as follows by atomic percentage: Al a Cr b Mo c Nb d Ni e Ti f V g , where 10 ≤ a ≤ 15, 10 ≤ b ≤ 20, 5 ≤ c ≤ 10, 10 ≤ d ≤ 20, 5 ≤ e ≤ 10, 5 ≤ f ≤ 10, 30 ≤ g ≤ 40, and a + b + c + d + e + f + g = 100.

2. The lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 1, characterized in that, The melting point of the lightweight and high-strength high-temperature resistant high-entropy alloy exceeds 1300 °C, and the density is 6.45 - 6.90 g / cm 3 , and the phase composition is BCC phase, Nb2NiAl phase and α-Ti phase.

3. The lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 1, characterized in that, The room temperature strain rate of the lightweight and high-strength high-temperature resistant high-entropy alloy is 0.001 s -1 , its room temperature yield strength is 1900 - 2145 MPa, and the compressive strength is 1920 - 2190 MPa; the strain rate of the lightweight and high-strength high-temperature resistant high-entropy alloy at 850 °C is 0.005 s -1 , the yield strength exceeds 1300 MPa, and the compressive strength exceeds 1400 MPa; at 1000 °C, the strain rate is 0.005 s -1 , the yield strength exceeds 720 MPa, and the compressive strength exceeds 800 MPa; the Vickers hardness value is 570 - 650 HV5.

4. A preparation method of the lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 1, characterized in that, The preparation method of the light-weight and high-strength high-temperature resistant high-entropy alloy is as follows: S1. Raw material weighing: Weigh high-purity metal particles of Al, Cr, Mo, Nb, Ni, Ti and V with a purity of 99.9 wt% or more according to the chemical composition of the light-weight and high-strength high-temperature resistant high-entropy alloy, and perform pretreatment to obtain the treated raw materials; S2. Melting and casting: The raw materials treated in S1 are melted multiple times by a vacuum melting process, and after casting, they are cooled to room temperature in the furnace to obtain alloy ingots; S3. Solution treatment of ingots: The alloy ingots in S2 are subjected to solution treatment in an argon atmosphere and cooled to room temperature with water to obtain the light-weight and high-strength high-temperature resistant high-entropy alloy.

5. The preparation method of the lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 4, characterized in that, The specific steps of S1 raw material weighing are as follows: S101. Carefully polish the surface of all high-purity metal particles with a grinding wheel or angle grinder to remove the surface oxide film or impurity layer, and then accurately weigh the mass of the required raw materials; S102. Place the weighed raw materials in a beaker containing absolute ethanol for ultrasonic oscillation cleaning for 3 - 5 minutes. After ultrasonic cleaning, rinse with absolute ethanol and quickly dry to remove the impurities remaining on the surface.

6. The preparation method of the lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 4, wherein The specific steps of S2 melting and casting are as follows: S201. Before melting, first pump the melting furnace to a vacuum degree of -4 magnitude, and then introduce high-purity argon with a purity of 99.999% until the internal pressure of the furnace is -0.05 MPa; S202. During the melting process, each alloy ingot is flipped and melted 5 - 7 times, with each time lasting 3 - 5 minutes, and an electromagnetic stirring function is used for stirring; after melting, it is cooled to room temperature in the furnace to obtain alloy ingots.

7. The preparation method of the lightweight and high-strength high-temperature resistant high-entropy alloy according to claim 4, wherein, The specific steps of S3 solution treatment of ingots are as follows: S301. Before solution treatment, first seal the experimental sample of the alloy ingot in a quartz tube in an argon atmosphere; S302. Place the quartz tube with the ingot sample in a box-type resistance furnace of KSI 1700X, set the heating rate to 4 - 6 °C / min, the solution temperature to 1150 - 1200 °C, and the holding time to 20 - 24 hours. After reaching the time, quickly clamp it out and break the quartz tube, and the sample falls into water for cooling to obtain the light-weight and high-strength high-temperature resistant high-entropy alloy.

8. Application of the light-weight and high-strength high-temperature resistant high-entropy alloy according to any one of claims 1 - 3 or the light-weight and high-strength high-temperature resistant high-entropy alloy prepared by the preparation method according to any one of claims 4 - 7 in the field of high-temperature structural materials.

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