Wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy, and preparation method and application thereof

Abstract

This invention relates to the field of alloy technology, specifically to a wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy, its preparation method, and its applications. The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy is composed of the following atomic percentages: V 32.6%~32.733%, Co 32.6%~32.733%, Ni 32.6%~32.734%, and Ta 1.8%~2.2%. By adding a specific atomic percentage of Ta, this invention significantly improves the wide-temperature-range mechanical properties of the medium-entropy alloy, enabling it to exhibit excellent comprehensive mechanical properties from -196℃ to 600℃.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and more specifically, to a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, its preparation method, and its applications. Background Technology

[0002] In recent years, medium-entropy alloys (MEAs), as an emerging metallic structural material, have gradually become a focus of attention in academia and industry. Research has found that equiatomic VCoNi medium-entropy alloys possess excellent comprehensive mechanical properties and show great application potential in fields with stringent requirements for comprehensive mechanical properties, such as aerospace, deep-sea engineering, and cryogenic storage and transportation containers.

[0003] However, the service temperature range of equiatomic VCoNi medium-entropy alloys remains limited. Existing technologies for improving the mechanical properties of VCoNi medium-entropy alloys do not address their high-temperature performance, or their mechanical properties over a wide temperature range.

[0004] Therefore, it is of great significance to further expand the service temperature range of equiatomic ratio VCoNi medium-entropy alloys so that they can exhibit excellent comprehensive mechanical properties over a wide temperature range (e.g., from deep cryogenic to high-temperature).

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range. By adding a specific atomic percentage of the refractory element Ta, the service temperature range of the medium-entropy alloy can be extended, enabling it to maintain excellent and stable comprehensive mechanical properties over a wide temperature range.

[0007] The second objective of this invention is to provide a method for preparing a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range.

[0008] The third objective of this invention is to provide applications of high-strength and high-toughness VCoNiTa medium-entropy alloys with wide temperature range service in aerospace, deep-sea engineering, energy and chemical engineering, advanced manufacturing and transportation, and biomedical fields.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: This invention first provides a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, which is composed of the following components in atomic percentage: V 32.6%~32.733%, Co 32.6%~32.733%, Ni 32.6%~32.734%, and Ta 1.8%~2.2%.

[0010] Furthermore, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1607 MPa, not less than 1982 MPa, and not less than 20% at -196℃.

[0011] Furthermore, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1469 MPa, not less than 1794 MPa, and not less than 25% at 25℃.

[0012] Furthermore, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1238 MPa, not less than 1569 MPa, and not less than 18% at 400℃, respectively.

[0013] Furthermore, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1191 MPa, not less than 1541 MPa, and not less than 17% at 500℃, respectively.

[0014] Furthermore, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1106 MPa, not less than 1303 MPa, and not less than 5% at 600℃.

[0015] Furthermore, the microstructure of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy consists of austenitic equiaxed crystals and spherical and rod-shaped precipitates distributed at grain boundaries and within the grains.

[0016] This invention also provides a method for preparing a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, comprising the following steps: melting raw materials containing V, Co, Ni and Ta elements to obtain a liquid alloy, and casting the liquid alloy to obtain an ingot; subjecting the ingot to hot rolling, solution treatment, cold rolling, annealing treatment and aging treatment in sequence to obtain the high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range.

[0017] Furthermore, the total deformation of the cold rolling is 74% to 76%.

[0018] Furthermore, the annealing temperature is 940℃~960℃.

[0019] Furthermore, the holding time for the annealing treatment is 2 to 4 minutes.

[0020] Furthermore, the annealing process is followed by quenching, and the time interval between the annealing process and the quenching process does not exceed 5 seconds.

[0021] Furthermore, the aging treatment temperature is 540℃~560℃.

[0022] Furthermore, the heat preservation time for the aging treatment is 10h~14h.

[0023] Furthermore, the cold rolling method is multi-pass cold rolling, with 11 passes. The deformation amount of each pass in the first 3 passes is 12%~14%, the deformation amount of each pass in the 4th and 5th passes is 8%~10%, the deformation amount of each pass in the 6th to 8th passes is 3%~5%, and the deformation amount of each pass in the 9th to 11th passes is 1%~3%.

[0024] Furthermore, the vacuum degree of the melting process is no greater than 5 Pa.

[0025] Furthermore, the refining temperature of the smelting is 1510℃~1610℃.

[0026] Furthermore, the refining time for the smelting is 10 min to 15 min.

[0027] Furthermore, the casting temperature is 1430℃~1530℃.

[0028] Furthermore, the casting time is 60s~80s.

[0029] Furthermore, the initial temperature of the hot rolling is 1100℃~1200℃.

[0030] Furthermore, the hot rolling method is multi-pass hot rolling, the number of hot rolling passes is 4, the deformation amount of each hot rolling pass is 4%~6%, and the total deformation amount after hot rolling is 19%~21%.

[0031] Furthermore, the solution temperature is 1180℃~1220℃.

[0032] Furthermore, the solid solution time is 2h to 3h.

[0033] The present invention also provides applications of wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloys or VCoNiTa medium-entropy alloys prepared according to the preparation method of wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloys in the fields of aerospace, deep-sea engineering, energy and chemical engineering, advanced manufacturing and transportation, and biomedicine.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: by adding a specific atomic percentage of Ta, the present invention significantly improves the wide temperature range mechanical properties of the medium entropy alloy, enabling the high strength and toughness VCoNiTa medium entropy alloy to exhibit excellent comprehensive mechanical properties in the range of -196℃ to 600℃. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 A schematic diagram of the tensile test dimensions for the uniaxial tensile test provided by the present invention; Figure 2 The annealed state (VCoNi) obtained in Example 1 of this invention. 98 Mechanical property test results of Ta2 alloy at different temperatures; Figure 3 The aging state (VCoNi) obtained in Example 1 of the present invention. 98 Mechanical property test results of Ta2 alloy at different temperatures; Figure 4 The annealed state (VCoNi) obtained in Example 1 of this invention. 98 Scanning electron microscope image of Ta2 alloy; Figure 5 The annealed state (VCoNi) obtained in Example 1 of this invention. 98 Transmission electron microscope image of Ta2 alloy; Figure 6 The annealed state (VCoNi) obtained in Example 1 of this invention. 98 High-energy synchrotron radiation diffraction pattern of Ta2 alloy; Figure 7 The aging state (VCoNi) obtained in Example 1 of the present invention. 98 Scanning electron microscope image of Ta2 alloy. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0038] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0039] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0040] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0041] In a first aspect, the present invention provides a high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, which is composed of the following components in atomic percentage: V 32.6%~32.733%, Co 32.6%~32.733%, Ni 32.6%~32.734%, and Ta 1.8%~2.2%. The Ta element can be 1.8%, 1.9%, 2.0%, 2.1%, or 2.2% in atomic percentage, that is, the V, Co, and Ni elements can each independently be 32.6%, 32.633%, 32.634%, 32.666%, 32.667%, 32.7%, 32.733%, or 32.734% in atomic percentage.

[0042] That is, the high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range is composed of V, Co, Ni and Ta elements. Among them, the atomic percentage of Ta is 1.8%~2.2%; the atomic ratio of V, Co and Ni is 1:1:1.

[0043] Based on the excellent mechanical properties of VCoNi medium-entropy alloys, this invention significantly enhances the wide-temperature-range mechanical properties of VCoNi medium-entropy alloys through Ta alloying, successfully developing a novel medium-entropy alloy with high strength and toughness over a wide temperature range. This alloy effectively overcomes the shortcomings of traditional materials that struggle to balance strength and toughness at extreme temperatures, enabling the material to exhibit excellent comprehensive mechanical properties from -196℃ to 600℃.

[0044] Specifically, the addition of Ta can induce lattice distortion, thereby significantly hindering dislocation movement and improving the strength of the material. Ta tends to combine with elements such as Co and Ni to form the κ phase distributed in the matrix, which acts as a "pinning" mechanism for dislocations, further enhancing the material's strength. In addition, the low diffusion rate of Ta atoms inhibits grain growth and second-phase coarsening, allowing the alloy to maintain a stable microstructure at high temperatures, thus improving its high-temperature strength.

[0045] In some specific embodiments, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1607 MPa, not less than 1982 MPa, and not less than 20% at -196℃.

[0046] In some specific embodiments, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1469 MPa, not less than 1794 MPa, and not less than 25% at 25°C.

[0047] In some specific embodiments, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1238 MPa, not less than 1569 MPa, and not less than 18% at 400℃.

[0048] In some specific embodiments, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1191 MPa, not less than 1541 MPa, and not less than 17% at 500℃.

[0049] In some specific embodiments, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength, and uniform elongation of not less than 1106 MPa, not less than 1303 MPa, and not less than 5% at 600℃.

[0050] It can be seen that the VCoNiTa medium-entropy alloy provided by this invention exhibits excellent comprehensive mechanical properties over a wide temperature range.

[0051] In some specific embodiments, the microstructure of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy consists of austenitic equiaxed crystals and spherical and rod-shaped precipitates distributed at grain boundaries and within the grains.

[0052] Secondly, the present invention provides a method for preparing the above-mentioned high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, comprising the following steps: melting raw materials containing V, Co, Ni and Ta elements to obtain a liquid alloy, and casting the liquid alloy to obtain an ingot; subjecting the ingot to hot rolling, solution treatment, cold rolling, annealing treatment and aging treatment in sequence to obtain the high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range.

[0053] The introduction of Ta element can improve the comprehensive mechanical properties of VCoNiTa medium-entropy alloys over a wide temperature range. This preparation method can obtain VCoNi medium-entropy alloys with excellent mechanical properties over a wide temperature range.

[0054] In some specific embodiments, the total deformation of the cold rolling is 74% to 76%; including but not limited to a point value of any one of 74%, 75%, and 76%, or a range between any two. By controlling the total deformation of the cold rolling, the microstructure can be significantly refined, including dislocation movement and entanglement, deformation twinning, and grain fragmentation, providing conditions for further annealing to obtain a fine-grained structure; however, if the cold rolling deformation is too high, it will cause the aggregation of micro-defects and stress concentration, thereby causing irreversible macro-defects.

[0055] In some specific embodiments, the annealing temperature is 940℃~960℃, including but not limited to any one of 940℃, 945℃, 950℃, 955℃, and 960℃, or a range between any two. The holding time for the annealing is 2min~4min, including but not limited to any one of 2min, 3min, and 4min, or a range between any two. The above-mentioned annealing temperature and annealing time are the minimum temperature and shortest time for the cold-rolled alloy to complete recrystallization, resulting in a uniform fine-grained structure that contributes to its excellent mechanical properties. If the annealing temperature and annealing time are below the given range, the alloy cannot complete recrystallization, retaining a large number of defects and reducing its plasticity. If the annealing temperature and annealing time are above the given range, grain coarsening will occur, leading to a decrease in alloy strength.

[0056] In some specific embodiments, the annealing treatment is followed immediately by quenching and cooling to room temperature, and the time interval between the annealing treatment and the quenching is no more than 5 seconds, including but not limited to any one of 5 seconds, 4 seconds, 3 seconds, 2 seconds, and 1 second, or any range between two of these values. By setting the time interval between the annealing treatment and the quenching to no more than 5 seconds, this invention avoids the formation of coarse precipitates due to slow cooling in the high-temperature range, which would degrade material properties.

[0057] In some specific embodiments, the aging treatment temperature is 540℃~560℃, including but not limited to any one of 540℃, 545℃, 550℃, 555℃, and 560℃, or a range between any two. The aging treatment holding time is 10h~14h, including but not limited to any one of 10h, 11h, 12h, 13h, and 14h, or a range between any two. The above-mentioned aging treatment temperature corresponds to the precipitation range of dispersed fine nano-precipitates (such as L12 and fine κ phases), and the above-mentioned aging time is the peak aging range; beyond this time, the improvement in material properties is no longer significant.

[0058] In some specific embodiments, the cold rolling method is multi-pass cold rolling, with 11 passes. The deformation amount per pass in the first three passes is 12%~14% (e.g., 12%, 13%, or 14%), the deformation amount per pass in the fourth and fifth passes is 8%~10% (e.g., 8%, 9%, or 10%), the deformation amount per pass in the sixth to eighth passes is 3%~5% (e.g., 3%, 4%, or 5%), and the deformation amount per pass in the ninth to eleventh passes is 1%~3% (e.g., 1%, 2%, or 3%). This invention controls the deformation amount to gradually decrease with increasing rolling passes. The deformation amount in the first three passes is controlled at 12%~14%, which is the maximum deformation amount to prevent the formation of macroscopic defects in the alloy. As microscopic defects accumulate, the deformation amount in subsequent passes gradually decreases, all with the aim of preventing the introduction of macroscopic defects.

[0059] In some specific embodiments, the cold rolling temperature is room temperature of 20~30°C, for example 23°C, 25°C or 28°C.

[0060] In some specific implementations, the vacuum degree of the melting process is no greater than 5 Pa.

[0061] In some specific embodiments, the refining temperature of the smelting is 1510℃~1610℃, including but not limited to any one of 1510℃, 1520℃, 1530℃, 1540℃, 1550℃, 1560℃, 1570℃, 1580℃, 1590℃, 1600℃, and 1610℃ or any range between two of these values; the refining time is 10min~15min, including but not limited to any one of 10min, 11min, 12min, 13min, 14min, and 15min or any range between two of these values.

[0062] In some specific embodiments, the melting is induction heating melting, which is carried out in a vacuum medium-frequency induction furnace.

[0063] In some specific embodiments, the casting temperature is 1430℃~1530℃, including but not limited to any one of 1430℃, 1440℃, 1450℃, 1460℃, 1470℃, 1480℃, 1490℃, 1500℃, 1510℃, 1520℃, and 1530℃, or a range between any two; the casting time is 60s~80s, including but not limited to any one of 60s, 65s, 70s, 75s, and 80s, or a range between any two.

[0064] In some specific embodiments, the mold used for casting includes an alumina mold shell, and the casting yields a rectangular ingot.

[0065] In some specific embodiments, the initial temperature of the hot rolling is 1100℃~1200℃, including but not limited to any one of 1100℃, 1120℃, 1130℃, 1150℃, 1160℃, 1180℃, and 1200℃, or any range between two of them.

[0066] In some specific embodiments, the hot rolling method is multi-pass hot rolling, the number of hot rolling passes is 4, the deformation amount of each hot rolling pass is 4% to 6% (e.g., 4%, 5% or 6%), and the total deformation amount after hot rolling is 19% to 21% (e.g., 19%, 20% or 21%). The purpose of hot rolling is to eliminate macroscopic defects.

[0067] In some specific embodiments, the hot rolling process yields a primary densified alloy billet with a thickness of 6 mm.

[0068] In some specific embodiments, the solution temperature is 1180℃~1220℃, including but not limited to any one of 1180℃, 1190℃, 1200℃, 1210℃, and 1220℃, or a range between any two; the solution time is 2h~3h, including but not limited to any one of 2h, 2.5h, and 3h, or a range between any two. If the solution temperature is below 1180℃, the homogenization process will be incomplete, and some precipitated phases will not be able to remelt; if the solution temperature is above 1220℃, burn-off will occur, rendering the alloy unusable.

[0069] In some specific embodiments, after the solid solution is completed, the solid solution product is cooled to obtain a solid solution alloy. The cooling method includes water cooling, and the water cooling temperature is room temperature (20~30℃). Then, the solid solution alloy is processed to a thickness of 5mm using cutting equipment such as an electrical discharge wire cutting machine.

[0070] Thirdly, the present invention provides applications of the above-mentioned high-strength and high-toughness VCoNiTa medium-entropy alloy with wide temperature range service, or the VCoNiTa medium-entropy alloy with wide temperature range service prepared according to the above-mentioned preparation method of the high-strength and high-toughness VCoNiTa medium-entropy alloy with wide temperature range service, in the fields of aerospace, deep-sea engineering, energy and chemical engineering, advanced manufacturing and transportation, and biomedicine.

[0071] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0072] Example 1 The preparation method of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy provided in this embodiment includes the following steps: (1) The raw material composed of V, Co, Ni and Ta elements is smelted, wherein the atomic ratio of V, Co, Ni and Ta elements is 32.667:32.667:32.668:2, to obtain (VCoNi). 98 The liquid alloy of Ta2 was smelted in a vacuum induction furnace under induction heating at a vacuum level of 5 Pa, a refining temperature of 1560 °C, and a refining time of 12 min.

[0073] (2) The liquid alloy obtained in step (1) is cast, wherein the casting temperature is 1480℃ and the casting time is 70s. After casting, a rectangular ingot is obtained. The mold used for casting is an alumina mold shell.

[0074] (3) The ingot obtained in step (2) is hot rolled, wherein the initial temperature of hot rolling is 1150℃, the hot rolling method is multi-pass hot rolling, the number of hot rolling passes is 4, the deformation amount of each hot rolling pass is 5%, the total deformation amount after hot rolling is 20%, and a primary densified alloy billet with a plate thickness of 6 mm is obtained after hot rolling.

[0075] (4) The primary densified alloy billet obtained in step (3) is subjected to solid solution treatment, wherein the solid solution temperature is 1200℃ and the solid solution time is 2h; after solid solution treatment, the solid solution product is cooled to obtain a solid solution alloy, wherein the cooling method is water cooling and the water cooling temperature is room temperature 25℃; then the thickness is processed to 5mm using an electric wire EDM machine.

[0076] (5) The solid solution alloy obtained in step (4) is cold rolled. The cold rolling temperature is room temperature 25°C. The rolling method is multi-pass cold rolling. The number of cold rolling passes is 11. The deformation amount of each pass in the first 3 passes is 13%. The deformation amount of each pass in the 4th and 5th passes is 9%. The deformation amount of each pass in the 6th to 8th passes is 4%. The deformation amount of each pass in the 9th to 11th passes is 2%. Finally, the total deformation amount of cold rolling is controlled to be 75%, and the cold-rolled alloy is obtained.

[0077] (6) The cold-rolled alloy obtained in step (5) is annealed at 950°C for 3 min and then immediately quenched to room temperature. The time interval between the annealing and quenching is 3 s to obtain the annealed alloy.

[0078] (7) The annealed alloy obtained in step (6) is aged at 550°C for 12 hours to obtain the aged alloy, namely the high strength and toughness VCoNiTa medium entropy alloy with wide temperature range service.

[0079] The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy prepared in this embodiment is composed of V, Co, Ni, and Ta elements, wherein the atomic percentage of Ta is 2%, and the atomic ratio of V, Co, and Ni is 1:1:1. That is, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy is composed of the following components according to atomic percentage: V 32.667%, Co 32.667%, Ni 32.668%, and Ta 2%.

[0080] Example 2 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that the atomic ratio of V, Co, Ni and Ta elements in the raw materials used in step (1) is 32.733:32.733:32.734:1.8, resulting in (VCoNi).98.2 Ta 1.8 Liquid alloys.

[0081] The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy prepared in this embodiment is composed of V, Co, Ni, and Ta elements, wherein the atomic percentage of Ta is 1.8%, and the atomic ratio of V, Co, and Ni is 1:1:1. That is, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy is composed of the following components according to atomic percentage: V 32.733%, Co 32.733%, Ni 32.734%, and Ta 1.8%.

[0082] Example 3 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that the atomic ratio of V, Co, Ni and Ta elements in the raw materials used in step (1) is 32.6:32.6:32.6:2.2, resulting in (VCoNi). 97.8 Ta 2.2 Liquid alloys.

[0083] The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy prepared in this embodiment is composed of V, Co, Ni, and Ta elements, wherein the atomic percentage of Ta is 2.2%, and the atomic ratio of V, Co, and Ni is 1:1:1. That is, the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy is composed of the following components according to atomic percentage: V 32.6%, Co 32.6%, Ni 32.6%, and Ta 2.2%.

[0084] Example 4 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that: in step (5), the number of cold rolling passes is 11, the deformation amount of each rolling pass in the first 3 passes is 14%, the deformation amount of each rolling pass in the 4th and 5th passes is 10%, the deformation amount of each rolling pass in the 6th to 8th passes is 3%, the deformation amount of each rolling pass in the 9th to 11th passes is 1%, and the total deformation amount of cold rolling is finally controlled to be 74%.

[0085] Example 5 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that: in step (5), the number of cold rolling passes is 11, the deformation amount of each rolling pass in the first 3 passes is 12%, the deformation amount of each rolling pass in the 4th and 5th passes is 8%, the deformation amount of each rolling pass in the 6th to 8th passes is 5%, the deformation amount of each rolling pass in the 9th to 11th passes is 3%, and the total deformation amount of cold rolling is finally controlled to be 76%.

[0086] Example 6 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that in step (6), annealing is performed at 940°C for 4 minutes.

[0087] Example 7 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that: in step (7), an aging treatment is performed at 540°C for 14 hours.

[0088] Example 8 The preparation method of the wide-temperature-range service high-strength and tough VCoNiTa medium-entropy alloy provided in this embodiment is basically the same as that in Example 1, except that: in step (4), the solid solution temperature is 1220℃ and the solid solution time is 2.5h.

[0089] Comparative Example 1 The preparation method of the VCoNiTa medium entropy alloy provided in this comparative example is basically the same as that in Example 1, except that the atomic ratio of V, Co, Ni and Ta elements in the raw materials used in step (1) is 32.266:32.267:32.267:3.2, resulting in (VCoNi). 96.8 Ta 3.2 Liquid alloys.

[0090] The VCoNiTa medium entropy alloy prepared in this comparative example consists of the following components in atomic percentage: V 32.266%, Co 32.267%, Ni 32.267%, and Ta 3.2%.

[0091] Comparative Example 2 The preparation method of the VCoNiTa medium entropy alloy provided in this comparative example is basically the same as that in Example 1, except that the atomic ratio of V, Co, Ni and Ta elements in the raw materials used in step (1) is 33:33:33:1, resulting in (VCoNi). 99 Ta1 liquid alloy.

[0092] The VCoNiTa medium entropy alloy prepared in this comparative example consists of the following components in atomic percentage: V 33%, Co 33%, Ni 33%, and Ta 1%.

[0093] Comparative Example 3 The preparation method of the VCoNiTa medium entropy alloy provided in this comparative example is basically the same as that in Example 1, except that: in step (5), the number of cold rolling passes is 11, the deformation amount of each rolling pass in the first 3 passes is 11%, the deformation amount of each rolling pass in the 4th and 5th passes is 6%, the deformation amount of each rolling pass in the 6th to 8th passes is 3%, the deformation amount of each rolling pass in the 9th to 11th passes is 1%, and the total deformation amount of cold rolling is finally controlled to be 60%.

[0094] Comparative Example 4 The preparation method of the VCoNiTa medium entropy alloy provided in this comparative example is basically the same as that in Example 1, except that in step (6), annealing is performed at 900°C for 3 minutes.

[0095] Comparative Example 5 The preparation method of the VCoNiTa medium entropy alloy provided in this comparative example is basically the same as that in Example 1, except that in step (7), an aging treatment is performed at 600°C for 12 hours.

[0096] Experimental Example The high-strength and high-toughness VCoNiTa medium-entropy alloys with wide temperature ranges and those prepared in each embodiment, as well as the VCoNiTa medium-entropy alloys prepared in each comparative example, were subjected to uniaxial tensile tests at -196℃, 25℃, 400℃, 500℃, and 600℃, respectively. The test results are shown in Table 1. The tensile test dimensions are as follows: Figure 1 As shown.

[0097] Table 1 Mechanical performance test results

[0098] Among them, the annealed state (VCoNi) obtained in step (6) of Example 1 98 The mechanical properties of Ta2 alloy at different temperatures are as follows: Figure 2 As shown, the aged state (VCoNi) obtained in step (7) of Example 1 98 The mechanical properties of Ta2 alloy (i.e., wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy) at different temperatures are as follows: Figure 3 As shown.

[0099] The results show that the annealed state (VCoNi) obtained in Example 1... 98The Ta2 alloy exhibits yield strength, tensile strength, and uniform elongation of 1356 MPa, 1727 MPa, and 22% at -196℃; 1133 MPa, 1528 MPa, and 27% at 25℃; 903 MPa, 1383 MPa, and 27% at 400℃; 945 MPa, 1388 MPa, and 12% at 500℃; and 1024 MPa, 1395 MPa, and 7% at 600℃. Additionally, the annealed state (VCoNi) obtained in Example 1... 98 The microstructure and phase analysis results of Ta2 alloy are as follows: Figure 4 , Figure 5 and Figure 6 As shown, its microstructure consists of austenitic equiaxed crystals and spherical and rod-shaped precipitates distributed at grain boundaries and within the grains.

[0100] The aged state (VCoNi) obtained in Example 1 98 The Ta2 alloy exhibits the following yield strengths, tensile strengths, and uniform elongation at -196℃: 1607 MPa, 1982 MPa, and 20%, respectively; at 25℃: 1469 MPa, 1794 MPa, and 25%, respectively; at 400℃: 1238 MPa, 1569 MPa, and 18%, respectively; at 500℃: 1191 MPa, 1541 MPa, and 17%, respectively; and at 600℃: 1106 MPa, 1303 MPa, and 5%, respectively. The aged state (VCoNi) obtained in Example 1... 98 The microstructure of Ta2 alloy is as follows Figure 7 As shown, its structure is also composed of austenitic equiaxed crystals and spherical and rod-shaped precipitates distributed at grain boundaries and within the grains.

[0101] In addition, the high-strength and high-toughness VCoNiTa medium-entropy alloys prepared in other embodiments all exhibit excellent comprehensive mechanical properties over a wide temperature range.

[0102] In Comparative Example 1, the excessive addition of Ta led to the formation of relatively large and locally aggregated precipitates after aging, which weakened the continuous deformation capability of the matrix and resulted in a significant decrease in the alloy's plasticity. In Comparative Example 2, the insufficient addition of Ta resulted in inadequate solid solution strengthening and precipitation strengthening, leading to limited strength improvement over a wide temperature range. Its yield strength at 25℃ and 500℃ was only 1260MPa and 884MPa, respectively, which were significantly lower than those of Example 1.

[0103] It is evident that the addition of Ta can induce lattice distortion, thereby significantly hindering dislocation movement and improving the material's strength. Ta tends to combine with elements such as Co and Ni to form the κ phase distributed in the matrix, acting as a "pinning" mechanism for dislocations, thus further enhancing the material's strength. Furthermore, the low atomic diffusion rate of Ta inhibits grain growth and second-phase coarsening, allowing the alloy to maintain a stable microstructure at high temperatures, thereby improving its high-temperature strength.

[0104] Furthermore, Comparative Example 3 suffered from insufficient deformation energy storage due to unsuitable cold rolling parameters, making it difficult to form a sufficiently fine and uniform recrystallized structure after subsequent annealing. This resulted in a weakened aging strengthening effect, and its yield strength at all temperatures was significantly lower than that of Example 1. Comparative Example 4 also suffered from insufficient recrystallization due to unsuitable annealing parameters, resulting in a large amount of residual deformation structure within the material. Although the local yield strength remained high, the uniform elongation was significantly reduced; for example, its uniform elongation at -196℃ and 25℃ was only 9% and 11%, respectively. Comparative Example 5 suffered from significant coarsening of the precipitates due to unsuitable aging parameters, leading to over-aging and a weakened dislocation pinning effect. Its yield strength at 25℃, 400℃, and 500℃ was only 1145 MPa, 896 MPa, and 858 MPa, respectively.

[0105] It is evident that controlling the preparation parameters can further enhance the comprehensive mechanical properties of VCoNiTa medium-entropy alloys over a wide temperature range.

[0106] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A high-strength, high-toughness VCoNiTa medium-entropy alloy with a wide temperature range, characterized in that, It is composed of the following components in atomic percentage: V 32.6%~32.733%, Co 32.6%~32.733%, Ni 32.6%~32.734% and Ta 1.8%~2.2%.

2. The high-strength and high-toughness VCoNiTa medium-entropy alloy with a wide temperature range according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy has a yield strength, tensile strength and uniform elongation of not less than 1607 MPa, not less than 1982 MPa and not less than 20% at -196℃, respectively; (2) The yield strength, tensile strength and uniform elongation of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy at 25℃ are not less than 1469MPa, not less than 1794MPa and not less than 25%, respectively; (3) The yield strength, tensile strength and uniform elongation of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy at 400℃ are not less than 1238MPa, not less than 1569MPa and not less than 18%, respectively; (4) The yield strength, tensile strength and uniform elongation of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy at 500℃ are not less than 1191MPa, not less than 1541MPa and not less than 17%, respectively; (5) The yield strength, tensile strength and uniform elongation of the wide temperature range high strength and toughness VCoNiTa medium entropy alloy at 600℃ are not less than 1106MPa, not less than 1303MPa and not less than 5%, respectively.

3. The wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 1 or 2, characterized in that, The microstructure of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy consists of austenitic equiaxed crystals and spherical and rod-shaped precipitates distributed at grain boundaries and within the grains.

4. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to any one of claims 1 to 3, characterized in that, Includes the following steps: A liquid alloy is obtained by melting raw materials containing V, Co, Ni and Ta elements, and the liquid alloy is then cast to obtain an ingot. The ingot is subjected to hot rolling, solution treatment, cold rolling, annealing and aging treatment in sequence to obtain the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy.

5. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The total deformation of the cold rolling is 74%~76%; (2) The annealing temperature is 940℃~960℃, and the annealing holding time is 2min~4min; (3) The annealing treatment is followed by quenching, and the time interval between the annealing treatment and the quenching is no more than 5 seconds; (4) The aging treatment temperature is 540℃~560℃, and the aging treatment holding time is 10h~14h.

6. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 4, characterized in that, The cold rolling method is multi-pass cold rolling, with 11 passes. The deformation amount of each pass in the first 3 passes is 12%~14%, the deformation amount of each pass in the 4th and 5th passes is 8%~10%, the deformation amount of each pass in the 6th to 8th passes is 3%~5%, and the deformation amount of each pass in the 9th to 11th passes is 1%~3%.

7. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The vacuum degree of the smelting is not greater than 5 Pa; (2) The refining temperature of the smelting is 1510℃~1610℃, and the refining time is 10min~15min; (3) The casting temperature is 1430℃~1530℃ and the casting time is 60s~80s.

8. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 4, characterized in that, The initial temperature of the hot rolling is 1100℃~1200℃, the hot rolling method is multi-pass hot rolling, the number of hot rolling passes is 4, the deformation of each hot rolling pass is 4%~6%, and the total deformation after hot rolling is 19%~21%.

9. The method for preparing the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy according to claim 4, characterized in that, The solution temperature is 1180℃~1220℃, and the solution time is 2h~3h.

10. Applications of the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy as described in any one of claims 1 to 3, or the wide-temperature-range service high-strength and high-toughness VCoNiTa medium-entropy alloy prepared by the preparation method according to any one of claims 4 to 9, in the fields of aerospace, deep-sea engineering, energy and chemical engineering, advanced manufacturing and transportation, and biomedicine.

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