High-strength and high-toughness eutectic high-entropy alloy and preparation method thereof

Abstract

The invention relates to the technical field of high-entropy alloys, in particular to a high-strength and high-toughness eutectic high-entropy alloy and a preparation method thereof. When the tensile strength of a conventional Ni-Fe-Co-Cr-Al eutectic high-entropy alloy exceeds 1100 Mpa and the yield strength of the conventional Ni-Fe-Co-Cr-Al eutectic high-entropy alloy is close to kilomega Pascal, the elongation of the conventional Ni-Fe-Co-Cr-Al eutectic high-entropy alloy is difficult to exceed 20%. In order to solve the technical problems, the invention provides the high-strength and high-toughness eutectic high-entropy alloy, the chemical components of the eutectic high-entropy alloy are designed as NiaFebCocCrdAleMof according to the atomic ratio, a is 35, b is 20, c is 15, d is 15, e is more than or equal to 12 and less than or equal to 15, f is more than or equal to 0 and less than or equal to 3, and a + b + c + d + e + f is 100. After the Ni35Fe20Co15Cr15Al14Mo1 eutectic high-entropy alloy is annealed for 70 min at the temperature of 800 DEG C, the microstructure is an FCC and BCC double-phase eutectic structure, the elongation at break is 26.6%, the yield strength is 914 MPa, the tensile strength is 1278 MPa, and excellent strength-plasticity balance is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-entropy alloys, and particularly relates to a high-strength and high-toughness eutectic high-entropy alloy and a preparation method thereof. BACKGROUND

[0002] In the field of metallic structural materials, the traditional alloy system often faces the bottleneck problems of mutual restriction between strength and toughness, insufficient performance in severe environments (such as low temperature and corrosive medium), and the like due to the limitation of design concept. In order to break through these limitations, high-entropy alloys, namely multi-principal-element alloys, emerge as the times require. The high-entropy alloys take five or more principal elements as basic components, effectively alleviate the inverted relationship between strength and toughness by means of the unique high-entropy effect and lattice distortion, and at the same time, excite excellent corrosion resistance and low-temperature fracture toughness, thereby opening up a new path for the design and industrial application of a new generation of high-performance structural materials.

[0003] The eutectic high-entropy alloy is expected to obtain an ideal solidification structure with uniform composition and fewer defects due to its inherent near-equilibrium solidification characteristics, and at the same time, has the high strength and toughness potential of the high-entropy alloy. However, the development of the current system is still in the exploratory stage, and a prominent technical bottleneck is that it is still very difficult to directly obtain an alloy with excellent strength and plasticity through simple composition design. The existing strategies are mostly focused on optimizing the performance through subsequent processing, but such methods often fall into the traditional dilemma of "strength-plasticity" trade-off. Taking the common Ni-Fe-Co-Cr-Al-based eutectic high-entropy alloy as an example, while pursuing the tensile strength exceeding 1100 MPa and the yield strength close to 1 GPa, the plasticity index (elongation) is usually limited to less than 20%, which greatly limits its application in structural components requiring high damage tolerance. SUMMARY

[0004] The existing technology has the problem that when the tensile strength of the conventional Ni-Fe-Co-Cr-Al eutectic high-entropy alloy exceeds 1100 MPa and has a yield strength close to 1 GPa, the elongation is difficult to exceed 20%. In view of the above technical problem, the present application provides a high-strength and high-toughness eutectic high-entropy alloy, the chemical composition of the eutectic high-entropy alloy is designed as Ni a Fe b Co c Cr d Al e Mo f , a=35, b=20, c=15, d=15, 12≤e≤15, 0≤f≤3, and a+b+c+d+e+f=100.

[0005] The technical scheme of the present application is implemented as follows: In a first aspect, the present application provides a high-strength and high-toughness eutectic high-entropy alloy, whose chemical composition is designed as Ni a Fe b Co c Cr d Al e Mo f wherein a = 35, b = 20, c = 15, d = 15, 12 ≤ e ≤ 15, 0 ≤ f ≤ 3, and a + b + c + d + e + f = 100.

[0006] Preferably, the chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein 1 ≤ f ≤ 3.

[0007] Preferably, the chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 15, f = 0.

[0008] Preferably, the chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 14, f = 1.

[0009] Preferably, the chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 12, f = 3.

[0010] Preferably, the eutectic high-entropy alloy comprises a dual-phase eutectic structure of FCC and BCC.

[0011] In a second aspect, the present application provides a preparation method of the eutectic high-entropy alloy according to the first aspect, comprising the following steps: S1, providing millimeter-level particles of industrial pure nickel with a purity ≥ 99.99%, millimeter-level particles of pure iron, millimeter-level particles of pure cobalt, millimeter-level particles of pure chromium, millimeter-level particles of pure aluminum, and millimeter-level particles of pure molybdenum for batching, and weighing the metal raw materials according to the atomic percentage of each element of Ni, Fe, Co, Cr, Al, and Mo; S2, raw materials Ni, Fe, Co, Cr, Al, Mo are sequentially placed in a copper mold crucible from low to high melting point in order from bottom to top to perform vacuum arc melting, and the alloy melt is obtained by repeatedly melting at least five times under the protection of argon atmosphere.

[0012] Preferably, the method further comprises the following step: S3, annealing the alloy melt obtained in step S2 at 700-900 DEG C under argon atmosphere, and water quenching.

[0013] Further preferably, the annealing time is 60-70 min; and the annealing temperature is most preferably 800 DEG C.

[0014] Preferably, the method further comprises a furnace cleaning step before step S2: the vacuum degree is extracted to 2.0*10 -3 Pa, and then argon is filled and washed at least twice, and finally, the ingot is melted by pure titanium for 2 times, each time for at least 120 seconds.

[0015] Preferably, the melting current of the vacuum arc melting is 400-450 A, and the arc lasts for 4-5 min each time.

[0016] Preferably, the vacuum arc melting is performed by electromagnetic stirring after each component raw material is melted into a liquid state, the electromagnetic stirring current is 10 A, and the duration is 2-3 min.

[0017] Compared with the prior art, the present application has the following advantages: (1) The present application provides a new type of high-strength and high-toughness eutectic high-entropy alloy Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1, the fracture elongation of the eutectic high-entropy alloy is 26.6%, the yield strength is 914 MPa, and the tensile strength is 1278 MPa, solving the problem of poor strength and plasticity matching of existing high-entropy alloys; (2) The present application uses a vacuum arc melting process to prepare the eutectic high-entropy alloy and uses one-step annealing to optimize the alloy performance, which is simple, safe and reliable; (3) The eutectic high-entropy alloy Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1 obtained by the present application has a microstructure of FCC and BCC dual-phase eutectic structure, achieving excellent strength-plasticity balance. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the Ni a Feb Co c Cr d Al e Mo f XRD pattern of eutectic high-entropy alloy; Figure 2 Ni-Fe-Co-Cr-Al-Mo alloy prepared in Example 1 of the present application a Fe b Co c Cr d Al e Mo f Microstructure image of eutectic high-entropy alloy; Figure 3 Ni-Fe-Co-Cr-Al-Mo alloy prepared in Example 2 of the present application a Fe b Co c Cr d Al e Mo f Room temperature tensile stress-strain curve of eutectic high-entropy alloy; Figure 4 Ni-Fe-Co-Cr-Al-Mo alloy prepared in Example 3 of the present application a Fe b Co c Cr d Al e Mo f XRD pattern of eutectic high-entropy alloy; Figure 5 Ni-Fe-Co-Cr-Al-Mo alloy prepared in Example 4 of the present application a Fe b Co c Cr d Al e Mo f Microstructure image of eutectic high-entropy alloy; Figure 6 Ni-Fe-Co-Cr-Al-Mo alloy prepared in Example 4 of the present application a Fe b Co c Cr d Al e Mo f Room temperature tensile stress-strain curve of eutectic high-entropy alloy. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0020] It should be noted that the present application emphasizes the strength of the alloy, not only to emphasize the tensile strength exceeding 1100 MPa, but also to have a yield strength of nearly gigapascal. However, the yield strength of the AlCoCrFeNi eutectic high-entropy alloy is generally lower than 700 MPa, such as in the documents 'Composition design, microstructure evolution and mechanical properties of AlCoCrFeNi-M (M = Mo, Ti) eutectic high-entropy alloys' and 'Mechanistic origin of abnormal annealing-induced hardening in an AlCoCrFeNi 2.1 eutectic multi-principal-element alloy', the yield strength can break through nearly a thousand megapascals when the tensile strength and elongation are both high.

[0021] In the present application, the FCC volume fraction increases with the increase of Mo content, and the BCC phase volume fraction decreases with the increase of Mo content. In addition, in the present application, the strength does not decrease from Mo0 alloy to Mo1 alloy, but the plasticity increases; to Mo3 alloy, the strength decreases and the plasticity improves. The above points are contrary to the existing literature reports. It may be due to the content design of Mo or Al.

[0022] Further, the content range of Mo is designed to control the volume fraction of FCC phase and BCC phase. Mo can partially replace Al to achieve the 'alloying toughening' of the intrinsic properties of the BCC phase. Mo atoms are dissolved in the BCC phase, not only enhancing its strength, but more importantly, by changing the electronic structure and bonding properties, significantly improving the cleavage resistance of the BCC phase, making it change from a traditional brittle phase to a 'toughened' hard phase that can bear and coordinate deformation. Thirdly, Mo segregation at the FCC / BCC phase interface stabilizes the interface structure, which can make the eutectic structure produce more persistent and stronger heterogeneous deformation-induced strengthening during deformation, thereby breaking through the traditional mutual exclusion relationship between strength and plasticity of eutectic alloys.

[0023] The present application first achieves this effect by adjusting the content of Mo or Al, and it is found that Mo partially replacing Al can achieve the 'alloying toughening' of the intrinsic properties of the BCC phase. Mo atoms are dissolved in the BCC phase, not only enhancing its strength, but more importantly, by changing the electronic structure and bonding properties, significantly improving the cleavage resistance of the BCC phase, making it change from a traditional brittle phase to a 'toughened' hard phase that can bear and coordinate deformation.

[0024] In addition, in the present application, ordered L12 phase is precipitated in the FCC phase after annealing, making the FCC phase change from'soft' to 'hard', and hindering the movement of dislocations, achieving a significant increase in strength and maintaining excellent plasticity.

[0025] It should be noted that the terms "first", "second" are only for descriptive purposes and cannot be understood to indicate or imply relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0026] In this document, the terms "containing", "including" or "comprising" are open expressions, i.e. including the indicated content of the present application, but not excluding other aspects.

[0027] In this document, the term "optional", "optionally" or "optional" generally means that the event or condition described thereafter can but does not necessarily occur, and the description includes cases where the event or condition occurs, as well as cases where it does not occur.

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0029] Unless otherwise specified, the materials and equipment used in the present application are commercially available in the art.

[0030] Example 1 The present embodiment provides a high-strength and high-toughness eutectic high-entropy alloy and a preparation method thereof, comprising the following steps: Before vacuum arc melting, a furnace cleaning operation is required, i.e. vacuumizing, then filling argon, then vacuumizing, and repeating the operation twice, so as to completely remove the air at the end of the pipeline in the furnace and ensure that the vacuum degree in the furnace is ≤2.0×10 -3 Pa.

[0031] In the present embodiment, Ni 35 Fe 20 Co 15 Cr 15 Al 15 Eutectic high-entropy alloy, namely Mo0 alloy, is prepared by the following method: using an electronic balance to weigh 39.20 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99 %, 21.32 g of pure iron millimeter-level particles, 16.87 g of pure cobalt millimeter-level particles, 14.89 g of pure chromium millimeter-level particles, and 7.72 g of pure aluminum millimeter-level particles, and placing them in a copper mold crucible in the order from low to high melting point from bottom to top and repeatedly melting five times, vacuumizing first and then filling argon, and ensuring that the vacuum degree in the furnace is ≤2.0×10-3 Pa.

[0032] During the smelting process, the smelting current is 400 A, and each smelting arc lasts for 4 min. After each component raw material is melted into a liquid state, electromagnetic stirring is performed, the electromagnetic stirring current is 10 A, and each duration is 2 min. Finally, the current is slowly returned to zero for cooling.

[0033] Example 2 The difference between this example and Example 1 is that: In this example, Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1 eutectic high-entropy alloy, namely Mo1 alloy, is prepared by using an electronic balance to respectively weigh 38.69 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 21.04 g of pure iron millimeter-level particles, 16.65 g of pure cobalt millimeter-level particles, 14.69 g of pure chromium millimeter-level particles, 7.12 g of pure aluminum millimeter-level particles, and 1.81 g of pure molybdenum millimeter-level particles. During the smelting process, the smelting current is 400 A, and each smelting arc lasts for 4 min. After each component raw material is melted into a liquid state, electromagnetic stirring is performed, the electromagnetic stirring current is 10 A, and each duration is 2 min. Finally, the current is slowly returned to zero for cooling.

[0034] The rest are the same as Example 1.

[0035] Example 3 The difference between this example and Example 1 is that: In this example, Ni 35 Fe 20 Co 15 Cr 15 Al 12 Mo3 eutectic high-entropy alloy, namely Mo3 alloy, is prepared by using an electronic balance to respectively weigh 37.71 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 20.51 g of pure iron millimeter-level particles, 16.23 g of pure cobalt millimeter-level particles, 14.32 g of pure chromium millimeter-level particles, 5.94 g of pure aluminum millimeter-level particles, and 5.28 g of pure molybdenum millimeter-level particles. During the smelting process, the smelting current is 400 A, and each smelting arc lasts for 4 min. After each component raw material is melted into a liquid state, electromagnetic stirring is performed, the electromagnetic stirring current is 10 A, and each duration is 2 min. Finally, the current is slowly returned to zero for cooling.

[0036] The rest are the same as Example 1.

[0037] The phase structure, microstructure and mechanical properties of the eutectic high-entropy alloys of the above embodiments 1-3 were characterized, and the test information is as follows: (1) Phase analysis: the phase composition of the eutectic high-entropy alloys prepared in embodiments 1-3 was characterized by X-ray diffractometer (XRD), the 2θ scanning range was 20°-90°, and the scanning speed was 3° / min, and the results are shown in Figure 1 It can be seen that the Ni a Fe b Co c Cr d Al e Mo f eutectic high-entropy alloy is a FCC+BCC dual-phase eutectic structure, and no precipitate phase is generated in it. However, as the Mo content increases, the diffraction peak shifts to low angle, indicating that significant lattice distortion occurs in the alloy.

[0038] (2) Microstructure: the microstructure of the eutectic high-entropy alloys prepared in embodiments 1-3 was characterized by scanning electron microscope (SEM), and the results are shown in Figure 2 It can be seen that the Ni a Fe b Co c Cr d Al e Mo f eutectic high-entropy alloy is a dual-phase eutectic structure, and as the Mo content increases, the volume fraction of FCC phase increases and the volume fraction of BCC phase decreases.

[0039] (3) Mechanical properties: the eutectic high-entropy alloys prepared in embodiments 1-3 were tested by room temperature tensile test using an electronic universal tensile testing machine, the tensile sample was a plate-shaped sample with a size of 46×8×2 mm 3 , and the strain rate was 1×10 -3 s -1 . At least three samples were tested for each sample to avoid accidental test results, and the results are shown in Figure 3 It can be seen that the as-cast Ni a Fe b Co c Cr d Al e Mo f eutectic high-entropy alloy, as the Mo content increases, its strength decreases and its plasticity increases. This is due to the increase of the volume fraction of FCC phase with the increase of Mo content, and the volume fraction of BCC phase is on the contrary. Among them, the as-cast Ni 35 Fe 20 Co 15 Cr 15 Al14 Mo1 eutectic high-entropy alloy has excellent comprehensive mechanical properties at room temperature, with a yield strength of 433 MPa, a tensile strength of 917 MPa, and an elongation of 34.3%. The Mo0 alloy of Example 1 has a yield strength of 424 MPa, a tensile strength of 920 MPa, and an elongation of 18.8%; the Mo3 alloy of Example 3 has a yield strength of 404 MPa, a tensile strength of 740 MPa, and an elongation of 36.5%.

[0040] Comparative Example 1

[0041] This comparative example has the same operation steps as Example 1, but differs in that: the comparative example is prepared by using an electronic balance to weigh 38.97 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 21.18 g of pure iron millimeter-level particles, 16.77 g of pure cobalt millimeter-level particles, 14.8 g of pure chromium millimeter-level particles, and 8.29 g of pure aluminum millimeter-level particles. 35 Fe 20 Co 15 Cr 15 ) 84 Al 16 eutectic high-entropy alloy, the preparation method is: using an electronic balance to weigh 38.97 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 21.18 g of pure iron millimeter-level particles, 16.77 g of pure cobalt millimeter-level particles, 14.8 g of pure chromium millimeter-level particles, and 8.29 g of pure aluminum millimeter-level particles.

[0042] Compared with Example 1 (Mo0), the alloy phase still maintains the FCC+BCC dual-phase eutectic structure, although its yield strength increases to 477 MPa, the tensile strength increases to 1058 MPa, and the elongation decreases to 12.8%. At this time, it is difficult to achieve a balance between strength and plasticity, because the increase in the Al content leads to an increase in the volume fraction of the BCC phase and a decrease in the volume fraction of the FCC phase; the relatively hard BCC phase, while improving the strength of the material, due to the excessive amount, can cause splitting of the material, reducing the plasticity of the material, making the material hard and brittle, which is the reason why Mo0 is used as the benchmark for Mo element substitution in the present application.

[0043] Comparative Example 2

[0044] This comparative example has the same operation steps as Example 2, but differs in that: the comparative example is prepared by using an electronic balance to weigh 38.97 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 21.18 g of pure iron millimeter-level particles, 16.77 g of pure cobalt millimeter-level particles, 14.8 g of pure chromium millimeter-level particles, and 8.29 g of pure aluminum millimeter-level particles. 35 Fe 20 Co 15 Cr 15 Al 15 ) 99 Mo1 eutectic high-entropy alloy, the preparation method is: using an electronic balance to weigh 38.97 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 21.18 g of pure iron millimeter-level particles, 16.77 g of pure cobalt millimeter-level particles, 14.8 g of pure chromium millimeter-level particles, and 8.29 g of pure aluminum millimeter-level particles.

[0045] Compared with Example 2 (Mo1), the alloy phase still maintains the FCC + BCC dual-phase eutectic structure, although the yield strength increases to 440 MPa and the tensile strength increases to 987 MPa, the strength is not much improved, but the elongation is greatly reduced to 15.1%, which is due to the increase of the volume fraction of BCC phase and the decrease of the volume fraction of FCC phase. The BCC phase belongs to the hard phase, and too much hard phase will increase the strength of the material but will deteriorate the plasticity of the material, and the decrease of the volume fraction of the relatively soft FCC phase will further reduce the plasticity of the material, which is not conducive to achieving the strength-plasticity balance. Therefore, the Mo element must only replace a part of the Al element, but not replace the whole Ni-Fe-Co-Cr-Al alloy. At the same time, this further illustrates that the sum of Mo element and Al element must be strictly matched according to the atomic ratio of 15%, otherwise it is difficult to achieve the strength-plasticity balance.

[0046] Comparative Example 3

[0047] The operation steps of the present comparative example are the same as those of Example 3, but the difference is that: the present comparative example prepares a Ni 35 Fe 20 Co 15 Cr 15 Al 10 Mo5 high-entropy alloy, and the preparation method is: using an electronic balance to weigh 36.78 g of industrial pure nickel millimeter-level particles with a purity of ≥99.99%, 20.00 g of pure iron millimeter-level particles, 15.83 g of pure cobalt millimeter-level particles, 13.97 g of pure chromium millimeter-level particles, 4.83 g of pure aluminum millimeter-level particles, and 8.59 g of pure molybdenum millimeter-level particles.

[0048] Compared with Example 3 (Mo3), the alloy phase has changed to single-phase FCC structure, no longer maintaining the eutectic structure, and the yield strength decreases to 380 MPa, the tensile strength decreases to 681 MPa, and the elongation increases to 48.5%. At this time, the relatively hard BCC phase completely disappears, and the matrix is not strengthened by the hard phase, although the plasticity of the material is greatly improved, but the strength is also greatly reduced, it is difficult to achieve the strength-plasticity balance.

[0049] Example 4 The eutectic high-entropy alloy prepared in Example 2 is taken as the object, and the alloy block is annealed at 700℃, 800℃ and 900℃ for 70 min under argon atmosphere, and then water quenched, namely 700A, 800A and 900A alloy blocks.

[0050] The phase structure, microstructure and mechanical properties of the eutectic high-entropy alloy of the above-mentioned Example 4 are characterized, and the test information is as follows: (1) Phase analysis: The phase composition of the eutectic high-entropy alloy prepared in Example 4 was characterized by an X-ray diffractometer, with a 2 theta scanning range of 20°-90° and a scanning speed of 3° / min, and the results are shown in Figure 4 It can be seen that after annealing, the Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1 eutectic high-entropy alloy still maintains the FCC+BCC dual-phase eutectic structure.

[0051] (2) Microstructure: The microstructure of the eutectic high-entropy alloy prepared in Example 4 was characterized by a scanning electron microscope, and the results are shown in Figure 5 It can be seen that after annealing, the Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1 eutectic high-entropy alloy still has a dual-phase eutectic structure, but as the annealing temperature increases, the volume fraction of the FCC phase continuously increases, and the volume fraction of the BCC phase continuously decreases.

[0052] (3) Mechanical properties: The eutectic high-entropy alloy prepared in Example 4 was subjected to room temperature tensile testing by using an electronic universal tensile testing machine, with a plate-shaped sample of 46×8×2 mm 3 , a strain rate of 1×10 -3 s -1 . At least three samples were tested for each sample to avoid accidental results, and the results are shown in Figure 6 It can be seen that after annealing, the Ni 35 Fe 20 Co 15 Cr 15 Al 14 Mo1 eutectic high-entropy alloy has more excellent mechanical properties at room temperature, and as the annealing temperature increases, the strength continuously decreases and the plasticity continuously increases. This is due to the increase in the volume fraction of the FCC phase and the decrease in the volume fraction of the BCC phase as the annealing temperature increases. Among them, after annealing at 800℃ for 70 min, the Ni 35 Fe 20 Co 15 Cr 15 Al 14The Mo1 eutectic high-entropy alloy has the best comprehensive mechanical properties at room temperature, with a fracture elongation of 26.6%, a yield strength of 914 MPa, and a tensile strength of 1278 MPa, achieving excellent strength-plasticity balance. The alloy annealed at 700 DEG C has a fracture elongation of 11.9%, a yield strength of 1104 MPa, and a tensile strength of 1407 MPa; the alloy annealed at 900 DEG C has a fracture elongation of 38.7%, a yield strength of 575 MPa, and a tensile strength of 942 MPa.

[0053] As can be known from the comparison of the above examples 1 to 4, Ni 35 Fe 20 Co 15 Cr 15 Al 14 The Mo1 eutectic high-entropy alloy achieves the strength-plasticity synergistic effect, with a fracture elongation of 26.6%, a yield strength of 914 MPa, and a tensile strength of 1278 MPa, and a microstructure of FCC+BCC dual-phase eutectic structure, solving the problem of poor strength-plasticity matching of existing high-entropy alloys.

[0054] The above-described embodiments are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

Claims

1. A high-strength high-toughness eutectic high-entropy alloy, characterized in that, Chemical composition: Ni a Fe b Co c Cr d Al e Mo f wherein a = 35, b = 20, c = 15, d = 15, 12 < e < 15, 0 < f < 3, and a + b + c + d + e + f = 100. 2.The co-crystal high-entropy alloy of claim 1, wherein, The chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein 1≤f≤3. 3.The co-crystal high-entropy alloy of claim 1, wherein, Its chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 15 and f = 0. 4.The co-crystal high-entropy alloy of claim 1, wherein, Its chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 14 and f = 1. 5.The co-crystal high-entropy alloy of claim 1, wherein, Its chemical composition is Ni a Fe b Co c Cr d Al e Mo f wherein e = 12, f = 3. 6.The co-crystal high-entropy alloy of claim 1, wherein, The eutectic high-entropy alloy comprises a dual-phase eutectic structure of FCC and BCC.

7. A method of preparing a co-crystal high-entropy alloy according to any one of claims 1-6, characterized in that, The method comprises the following steps: S1, providing millimeter-sized particles of industrial pure nickel with a purity of ≥99.99%, millimeter-sized particles of pure iron, millimeter-sized particles of pure cobalt, millimeter-sized particles of pure chromium, millimeter-sized particles of pure aluminum, and millimeter-sized particles of pure molybdenum for batching, and weighing the metal raw materials according to the atomic percentage of each element of Ni, Fe, Co, Cr, Al, and Mo; S2, placing the raw materials of Ni, Fe, Co, Cr, Al, and Mo in a copper mold crucible in the order from low to high melting point from bottom to top for vacuum arc melting, and repeatedly melting at least five times under the protection of an argon atmosphere to obtain an alloy melt.

8. The production method according to claim 7, characterized by, The method further comprises the following steps: S3, annealing the alloy melt obtained in step S2 at 700-900 DEG C under an argon atmosphere and water quenching.

9. The preparation method according to claim 7, characterized in that, Before step S2, there is also a furnace washing step: the vacuum degree is drawn to 2.0 x 10 -3 Pa, then argon is filled to wash the furnace at least twice, and finally, the pure titanium is smelted for ingot casting for 2 times, at least 120 seconds for each time.

10. The preparation method according to claim 7, characterized in that, The melting current of the vacuum arc melting is 400-450 A, and the arc lasts for 4-5 min each time.

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