High-toughness NbxTiyVmZrn series refractory multi-principal-element alloy and preparation method thereof

Abstract

The invention provides a high-toughness NbxTiyVmZrn series refractory multi-principal element alloy and a preparation method thereof. The NbxTiyVmZrn series refractory multi-principal element alloy comprises the following chemical components: Nb: x is more than or equal to 0.05 and less than or equal to 0.10 at%; ti: 0.35 < = y < = 0.40 at%; v: 0.35 < = m < = 0.4 at%; zr: 0.15 < = n < = 0.2 at%, and x + y + m + n = 1, the problems that traditional refractory alloy is poor in plasticity and large in brittleness are solved, the yield strength of the prepared refractory multi-principal-element alloy at the room temperature can reach 1500 MPa or above, the strain rate is close to 25%, and the refractory multi-principal-element alloy is expected to be applied to the field of high-temperature materials. The preparation method of the alloy is simple and easy to implement, and has the condition for realizing batch production.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy casting, and relates to a high-strength and tough Nb x Ti y V m Zr n series refractory multi-principal element alloy and a preparation method thereof. Background Art

[0002] With the rapid progress of modern industry and technology, the demand for materials under extreme high-temperature conditions has shown a significant growth trend, which has greatly promoted the research and development in the field of materials science. Especially in the aerospace field, when high-speed aircraft and deep-space detectors cross the atmosphere or perform interstellar missions, they need to withstand extremely high temperatures and extreme thermal stresses. This requires their structural materials to not only have excellent lightweight and high-strength characteristics, but also maintain excellent mechanical properties and thermal stability under extreme high temperatures. In the aspect of energy equipment, such as high-efficiency gas turbines, nuclear power plant reactors, and advanced solar thermal conversion systems, the core components of these facilities also need to be able to withstand high-temperature and high-pressure environments for a long time without deformation or failure to ensure energy conversion efficiency and safe operation. The chemical machinery industry also has special requirements for high-temperature materials. Especially in the fields of petrochemical industry and fine chemical industry, chemical reactions under high temperature and high pressure are often involved in reactors and pipelines. This requires the materials used to not only be corrosion-resistant and wear-resistant, but also maintain stable chemical properties and good mechanical strength under specific high-temperature conditions to avoid leakage and safety accidents.

[0003] However, traditional refractory alloys, such as tungsten, molybdenum, tantalum and their alloys, although having relatively high melting points, are often limited in practical applications due to problems such as poor plasticity, high brittleness and difficult processing. These characteristics limit their applications in the manufacture of complex-shaped components, especially in occasions that need to undergo thermal cycling and drastic temperature changes, where cracks and fractures are likely to occur, thus affecting the reliability and lifespan of the entire system. In recent years, "refractory multi-element alloys" composed mainly of refractory elements such as Ti, V, Nb, Zr, Hf, Ta, Cr, Mo, W, etc., as an important branch of multi-principal element alloys, due to their unique multi-element composition and uniform microstructure, while retaining the characteristics of high-entropy alloys, also have high melting points, showing excellent mechanical properties and potential high-temperature application prospects. However, the plasticity and toughness of existing refractory multi-principal element alloys at room temperature and high temperature still need to be improved, especially to achieve good plastic deformation ability while maintaining high strength. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a high-strength and tough Nb x Ti y V m Zrn It is a refractory multi-principal element alloy and its preparation method, which solves the problems of poor plasticity and high brittleness of refractory multi-principal element alloys.

[0005] The present invention is realized through the following technical solutions:

[0006] A high-strength and tough Nb x Ti y V m Zr n series refractory multi-principal element alloy, the Nb x Ti y V m Zr n The chemical composition of the series refractory multi-principal element alloy is Nb: 0.05 ≤ x ≤ 0.10 at%; Ti: 0.35 ≤ y ≤ 0.40 at%; V: 0.35 ≤ m ≤ 0.4 at%; Zr: 0.15 ≤ n ≤ 0.2 at%, where x + y + m + n = 1.

[0007] Preferably, the yield strength of the Nb x Ti y V m Zr n series refractory multi-principal element alloy reaches above 1500 MPa at room temperature, and the strain rate reaches 25%.

[0008] Preferably, the density of the Nb x Ti y V m Zr n series refractory multi-principal element alloy is 6.3 g / cm 3 , and the hardness value reaches 291.2 HV.

[0009] A preparation method of a high-strength and tough Nb x Ti y V m Zr n series refractory multi-principal element alloy, including,

[0010] S1, Weigh the metal particles of Nb, Ti, V, and Zr according to the atomic ratio of the predetermined alloy composition, and set aside after pretreatment;

[0011] S2, Place the pretreated metal particles of Nb, Ti, V, and Zr in the crucible of the melting furnace in the order of increasing melting point. After evacuating the vacuum, carry out vacuum arc melting under an argon atmosphere;

[0012] S3, After repeating vacuum arc melting for multiple times and cooling to room temperature, obtain a high-strength and tough Nb x Ti y V m Zr n series refractory multi-principal element alloy.

[0013] Preferably, the pretreatment process of S1 is as follows:

[0014] Remove the surface oxide layer of the metal particles of Nb, Ti, V, and Zr, then rinse with alcohol, ultrasonically clean, and dry for later use.

[0015] Preferably, the surface oxide layer of the metal particles of Nb, Ti, V, and Zr is removed by sandpaper grinding.

[0016] Preferably, the pretreated metal particles of Nb, Ti, V, and Zr are placed in the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace.

[0017] Preferably, the vacuum requirement condition of S2 is to reduce the vacuum degree in the melting furnace to below 6.0×10 -3 Pa.

[0018] Preferably, the parameters of the vacuum arc melting are set as the arc starting current of 60 A and the melting current of 300 A.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention provides a high-strength and tough Nb x Ti y V m Zr n series refractory multi-principal element alloy and its preparation method. The chemical composition of the Nb x Ti y V m Zr n series refractory multi-principal element alloy is Nb: 0.05≤x≤0.10 at%; Ti: 0.35≤y≤0.40 at%; V: 0.35≤m≤0.4 at%; Zr: 0.15≤n≤0.2 at%, where x + y + m + n = 1, which solves the problems of poor plasticity and high brittleness of traditional refractory alloys. The refractory multi-principal element alloy prepared by the present invention has a yield strength of more than 1500 MPa at room temperature and a strain rate close to 25%, and is expected to be applied in the field of high-temperature materials. The alloy preparation method of the present invention is simple and easy to implement, and has the conditions for realizing batch production. Brief Description of the Drawings

[0021] Figure 1 It is the micrograph of the high-strength and tough refractory multi-principal element alloy of Example 1; among them, (a) low-magnification metallography; (b) high-magnification metallography; (c) low-magnification scanning; (d) high-magnification scanning;

[0022] Figure 2 For Example 1 Nb 0.09 Ti 0.37 V0 .37Zr 0.18 XRD diffraction pattern of refractory multi-principal element alloy

[0023] Figure 3 For Nb in Example 1 0.09 Ti 0.37 V0 .37 Zr 0.18 Room temperature compression stress-strain curve of refractory multi-principal element alloy

[0024] Figure 4 Comparison chart of microhardness values for Examples 1 - 3

[0025] Figure 5 Nanoscale indentation test pair chart for Examples 1 - 3

[0026] Figure 6 For Nb in Comparative Example 1 0.09 Ti 0.37 V0 .37 Zr 0.18 XRD diffraction pattern of refractory multi-principal element alloy after annealing

[0027] Figure 7 For Nb in Comparative Example 1 0.09 Ti 0.37 V0 .37 Zr 0.18 Microscopic morphology diagram of refractory multi-principal element alloy in the annealed state; where, (a) low magnification metallography; (b) high magnification metallography; (c) low magnification scanning; (d) high magnification scanning. Detailed implementation manners

[0028] The following further elaborates on the present invention in conjunction with specific examples, which are explanations rather than limitations of the present invention.

[0029] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Example 1:

[0031] In this example, the chemical composition expression of the refractory multi-principal element alloy is Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 .

[0032] In this example, Nb 0.09 Ti0.37 V0 .37 Zr 0.18 The preparation method of the refractory multi-principal alloy comprises the following steps:

[0033] S1. Use pure metal particles with a purity of more than 99.9% as raw materials, calculate the mass required for each pure metal according to the atomic ratio of the designed alloy components, and weigh the raw materials according to the mass fraction of the designed components using an electronic balance with an accuracy of 0.1mg. The error range of weighing is accurate to ±0.001g, and the alloy is proportioned. Table 1 shows the actual proportioning of high-strength and refractory multi-principal alloys. Use sandpaper to remove the oxide layer on the surface of Nb, Ti, V, and Zr, ultrasonically clean the polished raw materials, put them into a drying oven for drying, and use them for smelting and preparing alloys;

[0034] Table 1 Actual ingredients of high-strength and tough refractory multi-principal alloy (g)

[0035]

[0036] S2. Place the raw materials in a water-cooled copper crucible in a WK-Ⅱ non-consumable vacuum melting furnace according to the principle of placing the pure metals from low to high melting points, that is, the pure metal particles with the lowest melting point are placed at the bottom of the crucible, and the pure metal particles with the highest melting point are placed at the top of the crucible. During the placement process, in order to ensure the uniformity of smelting, the metal particles in the crucible should be laid as flat as possible. After the raw materials are placed, close and tighten the furnace door, vacuumize the furnace body, and wait until the vacuum degree in the furnace chamber is lower than 6.0×10 -3 After Pa, argon gas is filled into the furnace chamber as a protective atmosphere to avoid interference from oxygen during the smelting process. The alloy is prepared by vacuum arc melting;

[0037] S3. In order to ensure that the alloy obtained by smelting is more uniform during vacuum smelting, each alloy ingot is smelted repeatedly for 4 times, with an arc current of 60A and a smelting current of 300A;

[0038] S4. The smelted material is cooled with the furnace, and when it cools to room temperature, it is taken out of the furnace and smelted to obtain Nb 0.65 Ti 0.16 V 0.13 Zr 0.06 Refractory multi-principal alloys.

[0039] The Nb obtained in this example 0.09 Ti 0.37 V0 .37 Zr 0.18 Microstructure characterization and mechanical properties testing of refractory multi-principal alloys:

[0040] (1) Alloy microstructure analysis

[0041] Samples with dimensions of 8×8×8 mm were wire-cut from the alloy ingots obtained in Example 1. The samples were polished with 1000-mesh sandpaper, and then polished with a velvet polishing cloth and a diamond polishing agent with a particle size of 1 μm until there were no scratches on the metallographic surface. The metallographic surface of the samples was etched with a corrosion solution of 2% HF + 3% HNO3 + 95% H2O, and the metallographic surface was rinsed with alcohol and dried with cold air for standby. The metallographic structure of the alloy was observed. The sample preparation method for scanning electron microscopy analysis was exactly the same as that of the metallographic samples, and the secondary electron imaging technology was used to observe the microstructure morphology of the alloy sample surface.

[0042] (2) Phase structure detection

[0043] Block alloys with dimensions of 5×5×5 mm were wire-cut from the alloy ingots obtained in Example 1, polished to 1000#, cleaned with alcohol and dried. XRD diffraction analysis was carried out, and the scanning angle range of 2θ was set to 20 - 100°, and the scanning speed was set to 5° / min.

[0044] (3) Density test

[0045] Block alloys with dimensions of 3×3×3 mm were wire-cut from the alloy ingots obtained in Example 1, and the surface was polished until the metal luster was exposed. The actual density of the as-cast high-strength, tough and refractory multi-principal element alloy was calculated and tested using the drainage method. The results showed that the density of the high-strength, tough and refractory multi-principal element alloy Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 was 6.34 g / cm 3 , and compared with traditional superalloys, the designed composition alloy had obvious advantages in density.

[0046] (4) Hardness test

[0047] Block alloys with dimensions of 8×8×8 mm were wire-cut from the alloy ingots obtained in Example 1, and the surface was polished until the metal luster was exposed. A microhardness tester was used to measure the hardness value of the alloy obtained in Example 1. The load was set to 1 kgf, and the holding time was set to 10 s. The microhardness value of the high-strength, tough and refractory multi-principal element alloy Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 reached 291.2 HV.

[0048] (5) Nanoindentation detection

[0049] Wire cut 8×8×3 mm bulk alloys from the alloy ingots obtained in Example 1, polish the surface until the metallic luster appears. When performing 5-point tests on the alloy surface, it is only necessary to ensure a certain distance between points. During the test, the indentation depth is set to 1200 nm, and the strain rate is set to 0.05 / s. The high-strength and tough refractory multi-principal element alloy Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 has a nano-hardness of 5.47 GPa and an elastic modulus of 119.9 GPa;

[0050] (6) Room temperature compression performance test

[0051] Wire cut a Φ4×6 mm cylindrical sample from the alloy ingot obtained in Example 1, and use sandpaper to polish off the wire cutting marks on the sample surface. Use an electronic universal testing machine to perform room temperature compression tests on the sample, and set the loading rate to 1 mm / s. The high-strength and tough refractory multi-principal element alloy Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 has a strength of up to 1523 MPa and a strain close to 25%, showing good strength and toughness.

[0052] Example 2:

[0053] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 .

[0054] In this example, the preparation method of the Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 refractory multi-principal element alloy includes the following steps:

[0055] S1. Use pure metal particles with a purity exceeding 99.9% as raw materials. According to the atomic ratio of the designed alloy composition, calculate the mass of each pure metal required. According to the mass fraction of the designed composition, use an electronic balance with a precision of 0.1 mg to weigh the raw materials. The error range during weighing is accurate to ±0.001 g to prepare the alloy ingredients. Use sandpaper to remove the oxide layers on the surfaces of Nb, Ti, V, and Zr. Ultrasonically clean the polished raw materials, and put them into a drying oven for drying for use in melting and preparing the alloy;

[0056] S2. According to the principle of placing pure metal particles in the raw materials from the lowest melting point to the highest, that is, the pure metal particles with the lowest melting point are placed at the bottom of the crucible, and the pure metal particles with the highest melting point are placed at the top of the crucible. Then put them into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After the raw materials are placed, close and tighten the furnace door, and perform a vacuum pumping operation on the furnace body. Wait until the vacuum degree in the furnace cavity is lower than 6.0×10 -3 Pa, and then fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. The alloy is prepared by vacuum arc melting;

[0057] S3. During the vacuum melting process, to ensure that the obtained alloy is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc starting current of 60 A and a melting current of 300 A;

[0058] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 refractory multi-principal element alloy.

[0059] The high-strength and tough refractory multi-principal element alloy Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 obtained in Example 2 has a microhardness of 287.2 HV, a nano-hardness of 5.46 GPa, and an elastic modulus of 121.5 GPa.

[0060] Example 3:

[0061] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 .

[0062] In this example, the preparation method of the Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 refractory multi-principal element alloy includes the following steps:

[0063] S1. Use pure metal particles with a purity exceeding 99.9% as raw materials. According to the atomic ratio of the designed alloy composition, calculate the mass of each pure metal required. According to the mass fraction of the designed composition, use an electronic balance with a precision of 0.1 mg to weigh the raw materials. The error range during weighing is accurate to ±0.001 g to prepare the alloy ingredients. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr, ultrasonically clean the polished raw materials, and put them into a drying oven for drying for use in melting and preparing the alloy;

[0064] S2. According to the principle of placing pure metals in the raw materials from the lowest melting point to the highest, that is, the pure metal particles with the lowest melting point are placed at the bottom of the crucible, and the pure metal particles with the highest melting point are placed at the top of the crucible. Then put them into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After the raw materials are placed, close and tighten the furnace door, and perform a vacuum pumping operation on the furnace body. Wait until the vacuum degree in the furnace cavity is lower than 6.0×10 -3 Pa, and then fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. The alloy is prepared by vacuum arc melting;

[0065] S3. During the vacuum melting process, to ensure that the obtained alloy is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc starting current of 60 A and a melting current of 300 A;

[0066] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 refractory multi-principal element alloy.

[0067] The high-strength and tough refractory multi-principal element alloy Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 prepared in this example has a microhardness of 293.4 HV, a nano-hardness of 5.38 GPa, and an elastic modulus of up to 120.1 GPa.

[0068] Figure 1 is the microstructure morphology of Example 1 Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 As shown, the alloy presents a typical dendritic morphology, in which the color inside the crystal is bright and the area accounts for a relatively large proportion, and the area between crystals is darker and connected into a network structure. Further, energy spectrum analysis shows that there is obvious segregation behavior of elements in the alloy. The Nb element and Zr element are easily enriched between crystals, the V element is easily enriched inside the crystal, and the Ti element is distributed both inside and between dendrites. Figure 1 The XRD results in Figure 2 further show that the phase composition of Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 is mainly a BCC duplex structure. Combining the microstructure analysis, it is considered that the inside of the dendrite is the BCC (rich in [Ti, V]) phase, and the area between dendrites is the BCC (NbTiZr) phase. Figure 3 is Nb in Example 10.09 Ti 0.37 V0 .37 Zr 0.18 Room temperature compression performance test results of

[0069] Figure 4 is Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 , Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 , Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 (Corresponding to Example 1, Example 2, and Example 3 respectively) Comparison of microhardness values of three examples, and error bars are in the form of standard deviation.

[0070] Figure 5 is Nb 0.09 Ti 0.37 V 0.36 Zr 0.18 , Nb 0.06 Ti 0.39 V 0.4 Zr 0.15 , Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 (Corresponding to Example 1, Example 2, and Example 3 respectively) Comparison of nanoindentation tests of three examples.

[0071] Example 4:

[0072] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.05 Ti 0.40 V 0.35 Zr 0.20 .

[0073] In this example, Nb 0.05 Ti 0.40 V 0.35 Zr 0.20 The preparation method of the refractory multi-principal element alloy includes the following steps:

[0074] S1. Use pure metal particles with a purity exceeding 99.9% as raw materials. Calculate the mass of each pure metal required according to the atomic ratio of the designed alloy composition. Weigh the raw materials using an electronic balance with an accuracy of 0.1 mg. When weighing, the error range is accurate to ±0.001 g to prepare the alloy ingredients. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr. Ultrasonically clean the polished raw materials, place them in a drying oven to dry, and use them for melting and preparing the alloy;

[0075] S2. According to the principle of placing the pure metals in the crucible from the lowest melting point to the highest, that is, placing the pure metal particles with the lowest melting point at the bottom of the crucible and the pure metal particles with the highest melting point at the top of the crucible, put them into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After placing the raw materials, close and tighten the furnace door, perform a vacuum pumping operation on the furnace body. After waiting for the vacuum degree in the furnace cavity to be lower than 6.0×10-3 Pa, fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. Prepare the alloy by means of vacuum arc melting;

[0076] S3. During the vacuum melting process, to ensure that the obtained alloy is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc starting current of 60 A and a melting current of 300 A;

[0077] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the refractory multi-principal element alloy Nb 0.05 Ti 0.40 V 0.35 Zr 0.20 refractory multi-principal element alloy.

[0078] The high-strength and tough refractory multi-principal element alloy Nb 0.05 Ti 0.40 V 0.35 Zr 0.20 prepared in this example has a microhardness of 283.4 HV, a nano-hardness of 5.32 GPa, and an elastic modulus of up to 120.2 GPa.

[0079] Example 5:

[0080] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.10 Ti 0.35 V 0.40 Zr 0.15 .

[0081] In this example, the preparation method of the Nb 0.10 Ti 0.35 V 0.40 Zr 0.15 refractory multi-principal element alloy includes the following steps:

[0082] S1. Use pure metal particles with a purity exceeding 99.9% as raw materials. Calculate the mass of each pure metal required according to the atomic ratio of the designed alloy composition. Weigh the raw materials using an electronic balance with an accuracy of 0.1 mg. When weighing, the error range is accurate to ±0.001 g to prepare the alloy ingredients. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr. Ultrasonically clean the polished raw materials and put them into a drying oven for drying, which is used for melting and preparing the alloy;

[0083] S2. Place the pure metal particles in the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace according to the principle of placing them from the lowest melting point to the highest melting point in the raw materials, that is, the pure metal particles with the lowest melting point are placed at the bottom of the crucible, and the pure metal particles with the highest melting point are placed at the top of the crucible. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After placing the raw materials, close and tighten the furnace door, perform a vacuum pumping operation on the furnace body. After waiting for the vacuum degree in the furnace cavity to be lower than 6.0×10-3 Pa, fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. Use the method of vacuum arc melting to prepare the alloy;

[0084] S3. To ensure that the alloy obtained by melting is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc starting current of 60 A and a melting current of 300 A;

[0085] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the refractory multi-principal element alloy Nb 0.10 Ti 0.35 V 0.40 Zr 0.15 refractory multi-principal element alloy.

[0086] The high-strength and tough refractory multi-principal element alloy Nb 0.10 Ti 0.35 V 0.40 Zr 0.15 prepared in this example has a microhardness of 291.4 HV, a nano-hardness of 5.33 GPa, and an elastic modulus of 119.4 GPa.

[0087] Comparative Example 1:

[0088] This comparative example provides a preparation method of Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 with the same composition as in Example 1 but different structures, specifically as follows:

[0089] In this comparative example, the chemical composition expression of the refractory multi-principal element alloy is Nb 0.09 Ti 0.37 V0.37 Zr 0.18

[0090] Nb in this comparative example 0.09 Ti 0.37 V0 .37 Zr 0.18 The preparation method of the refractory multi - principal - element alloy comprises the following steps:

[0091] S1. Using pure metal particles with a purity exceeding 99.9% as raw materials, calculate the mass of each pure metal required according to the atomic ratio of the designed alloy composition. According to the mass fraction of the designed composition, use an electronic balance with a precision of 0.1 mg to weigh the raw materials. When weighing, the error range is accurate to ±0.001 g for alloy batching. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr, ultrasonically clean the polished raw materials, and put them into a drying oven for drying for use in melting and preparing the alloy;

[0092] S2. According to the principle of placing the pure metals in the raw materials from the lowest melting point to the highest melting point, that is, placing the pure metal particles with the lowest melting point at the bottom of the crucible and the pure metal particles with the highest melting point at the top of the crucible, put them into the water - cooled copper crucible of the WK - Ⅱ type non - consumable vacuum melting furnace. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After the raw materials are placed, close and tighten the furnace door, perform a vacuum pumping operation on the furnace body, and wait until the vacuum degree in the furnace cavity is lower than 6.0×10 -3 Pa, then fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. Use the vacuum arc melting method to prepare the alloy;

[0093] S3. During the vacuum melting process, to ensure that the obtained alloy is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc - starting current of 60 A and a melting current of 300 A;

[0094] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the Nb 0.65 Ti 0.16 V 0.13 Zr 0.06 refractory multi - principal - element alloy.

[0095] S5. After the as - cast alloy is prepared, place the as - cast alloy in a box - type resistance furnace for annealing treatment at 1200 °C for 20 h.

[0096] The structure and mechanical property testing method of the refractory multi - principal - element alloy in this comparative example are the same as those in Example 1. Figure 6 Shows the XRD results of the comparative example Nb 0.09 Ti 0.37 V 0.37 Zr 0.18 refractory multi - principal - element alloy,Figure 7 Shows the comparative example Nb 0.09 Ti 0.37 V 0.37 Zr 0.18 The metallographic and SEM results of the refractory multi - principal - element alloy

[0097] The refractory multi - principal - element alloy Nb prepared in this comparative example 1 0.09 Ti 0.37 V0 .37 Zr 0.18 Consists of a duplex structure of BCC phase and hexagonal phase, showing a typical dendritic morphology. There are fine granular phases in both the dark dendritic inner region and the bright interdendritic region. Using a scanning electron microscope to magnify and observe this microstructure, discrete fine precipitated phases can be seen inside the dendrites, and continuous layered structures exist between the grains. Further, the annealed alloy is subjected to a room - temperature compression test. The room - temperature yield strength of this alloy is only about 863 MPa, the strain during compression is less than 5%, brittle fracture occurs at room temperature, and the plasticity is poor and it cannot be applied to practical engineering.

[0098] Comparative example 2

[0099] Taking the control test as a comparative example, such as the reaction temperature is 20 - 50 °C, test schemes corresponding to reaction temperatures outside the range of 20 - 50 °C can be provided

[0100] This comparative example 2 prepares the refractory high - entropy alloy outside the range according to the embodiment scheme, and the chemical composition expression is Nb 0.08 Ti 0.37 V 0.35 Zr 0.20 .

[0101] The Nb of this comparative example 2 0.08 Ti 0.37 V 0.35 Zr 0.20 The preparation method of the refractory multi - principal - element alloy includes the following steps

[0102] S1. Using pure metal particles with a purity exceeding 99.9% as raw materials, calculate the mass of each pure metal required according to the atomic ratio of the designed alloy composition. According to the mass fraction of the designed composition, use an electronic balance with a precision of 0.1 mg to weigh the raw materials, and the error range during weighing is accurate to ±0.001 g to prepare the alloy ingredients. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr, ultrasonically clean the polished raw materials, put them into a drying oven for drying, and use them for melting and preparing the alloy;

[0103] S2. According to the principle of placing pure metals in the raw materials from the lowest melting point to the highest, that is, the pure metal particles with the lowest melting point are placed at the bottom of the crucible, and the pure metal particles with the highest melting point are placed at the top of the crucible. Then put them into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace. During the placement process, to ensure the uniformity of melting, the metal particles in the crucible should be paved as flat as possible. After the raw materials are placed, close and tighten the furnace door, and perform a vacuum pumping operation on the furnace body. Wait until the vacuum degree in the furnace cavity is lower than 6.0×10 -3 Pa, and then fill the furnace cavity with argon as a protective atmosphere to avoid the interference of oxygen during the melting process. The alloy is prepared by vacuum arc melting;

[0104] S3. During the vacuum melting process, to ensure that the obtained alloy is more uniform, each alloy ingot is repeatedly melted 4 times, with an arc starting current of 60 A and a melting current of 300 A;

[0105] S4. The melted material is cooled with the furnace and taken out of the furnace when it cools to room temperature to obtain the Nb 0.07 Ti 0.39 V 0.36 Zr 0.18 refractory multi-principal element alloy.

[0106] The microhardness of the high-strength and tough refractory multi-principal element alloy Nb 0.08 Ti 0.37 V 0.35 Zr 0.20 prepared in this Comparative Example 2 is 202.0 HV, the room temperature yield strength is about 710 MPa, the strength and toughness are poor, and brittle fracture is likely to occur.

[0107] The above is only the preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention; any ordinary technician in the industry can smoothly implement the present invention according to the illustrations in the specification and the above description; however, any minor changes, modifications, and equivalent variations made by those skilled in the art within the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and variations made to the above embodiments based on the essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-strength and tough Nb x Ti y V m Zr n It is a refractory multi-principal alloy, characterized in that: The Nb x Ti y V m Zr n The chemical composition of the refractory multi-principal alloy is Nb: 0.05≤x≤0.10at%; Ti: 0.35≤y≤0.40at%; V: 0.35≤m≤0.4at%; Zr: 0.15≤n≤0.2at%, where x+y+m+n=1.

2. A high-strength and tough Nb according to claim 1 x Ti y V m Zr n It is a refractory multi-principal alloy, characterized in that: The Nb x Ti y V m Zr n The yield strength of the refractory multi-principal alloy reaches over 1500MPa at room temperature and the strain rate reaches 25%.

3. A high-strength and tough Nb according to claim 1 x Ti y V m Zr n It is a refractory multi-principal alloy, characterized in that: The Nb x Ti y V m Zr n The density of the refractory multi-element alloy is 6.3g / cm 3 , the hardness value reaches 291.2HV.

4. A high-strength and tough Nb according to any one of claims 1 to 3 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: include, S1, weighing metal particles of Nb, Ti, V and Zr according to the atomic ratio of the predetermined alloy components, and pre-treating them for use; S2, placing the pretreated metal particles of Nb, Ti, V, and Zr in the crucible of a melting furnace in the order of melting points from low to high, and after evacuation, performing vacuum arc melting in an argon atmosphere; S3, after repeated vacuum arc melting, is cooled to room temperature to obtain high-strength and tough Nb x Ti y V m Zr n It is a refractory multi-principal alloy.

5. A high-strength and tough Nb according to claim 4 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: The preprocessing process of S1 is: The surface oxide layer of the metal particles of Nb, Ti, V and Zr is removed, and then the particles are rinsed with alcohol, ultrasonically cleaned and dried for later use.

6. A high-strength and tough Nb according to claim 5 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: The surface oxide layer of the metal particles of Nb, Ti, V and Zr was removed by sandpaper grinding.

7. A high-strength and tough Nb according to claim 4 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: The pretreated metal particles of Nb, Ti, V and Zr are placed in a water-cooled copper crucible of a WK-II type non-consumable vacuum melting furnace.

8. A high-strength and tough Nb according to claim 4 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: The vacuum requirement of S2 is to reduce the vacuum degree in the melting furnace to 6.0×10 -3 Below Pa.

9. A high-strength and tough Nb according to claim 4 x Ti y V m Zr n The invention relates to a method for preparing a refractory multi-principal alloy, characterized in that: The parameters of the vacuum arc melting are set as an arc striking current of 60A and a melting current of 300A.

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