High-strength heat-resistant Nb < x > Ti < y > V < m > Zr < n > series refractory multi-principal-element alloy and preparation method

Abstract

The invention discloses a high-strength heat-resistant Nb < x > Ti < y > V < m > Zr < n > series refractory multi-principal-element alloy, and belongs to the technical field of alloy casting. Ti: 0.55 < = y < = 0.60 at%; v: 0.00 < = m < = 0.05 at%; zr: 0.10 < = n < = 0.15 at%. X + y + m + n = 1, the prepared refractory multi-principal-element alloy has the advantage of high strength of a single BCC phase structure, the microhardness reaches 450 HV or above, and the refractory multi-principal-element alloy has good thermal stability within the temperature range of 1450 DEG C or below. The problems that the refractory multi-principal-element alloy is poor in thermal stability in a medium-temperature interval and the mechanical property is reduced are solved, and the refractory multi-principal-element alloy has a good development prospect in the application field with the high strength requirement and the good thermal stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy manufacturing, and relates to a high-strength and heat-resistant 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 development of modern industry, especially high-tech industries, the requirements for material properties are becoming increasingly stringent, especially in cutting-edge scientific and technological fields such as aerospace, energy and power, and chemical production. In these fields, materials often need to withstand extreme high-temperature environments while maintaining good mechanical properties and chemical stability. Therefore, the requirements for the high-temperature properties of materials, including high-temperature strength, creep resistance, oxidation resistance, etc., are continuously increasing.

[0003] Refractory multi-principal element alloys, as a new type of high-performance material, have emerged under this demand background and gradually demonstrated their unique advantages and broad application prospects. Such alloys are usually composed of multiple refractory metal elements, such as tungsten, molybdenum, tantalum, niobium, rhenium, etc. Through precise alloying design and preparation processes, they can maintain excellent mechanical properties at extremely high temperatures. Refractory multi-principal element alloys have become key materials in these fields due to their excellent high-temperature strength, good creep resistance, and high-temperature oxidation resistance. However, the existing refractory alloys often have certain limitations in terms of thermal stability and strength in high-temperature environments, which restricts their application under extreme conditions. Traditional refractory alloys have insufficient thermal stability at high temperatures and are prone to phase transformation, resulting in a decline in their mechanical properties. Especially during long-term high-temperature service, the strength of the alloy will decrease significantly. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a high-strength and heat-resistant Nb x Ti y V m Zr n series refractory multi-principal element alloy and a preparation method thereof, which solves the problems of poor thermal stability and decline in mechanical properties of refractory multi-principal element alloys in the medium-temperature range.

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

[0006] A high-strength and heat-resistant Nb x Ti y V m Zr n series refractory multi-principal element alloy, wherein the Nb x Ti y V m Zr nThe chemical composition of the refractory multi-principal element alloy is Nb: 0.25 ≤ x ≤ 0.30 at%; Ti: 0.55 ≤ y ≤ 0.60 at%; V: 0.00 ≤ m ≤ 0.05 at%; Zr: 0.10 ≤ n ≤ 0.15 at%, where x + y + m + n = 1.

[0007] Preferably, the Nb x Ti y V m Zr n The density of the refractory multi-principal element alloy does not exceed 7 g / cm 3 .

[0008] Preferably, the Nb x Ti y V m Zr n The hardness value of the refractory multi-principal element alloy reaches 464.2 HV.

[0009] Preferably, a high-strength and heat-resistant Nb x Ti y V m Zr n Preparation method of the 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 ascending order of melting point. After evacuating, carry out vacuum arc melting under an argon atmosphere;

[0012] S3, After multiple repetitions of vacuum arc melting are completed, cool to room temperature to obtain a high-strength and heat-resistant Nb x Ti y V m Zr n Refractory multi-principal element alloy.

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

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

[0015] Preferably, use the sandpaper grinding method to remove the surface oxide layer of the metal particles of Nb, Ti, V, and Zr.

[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 requirement for vacuum pumping 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 discloses a high-strength and heat-resistant Nb x Ti y V m Zr n series refractory multi-principal element alloy. The chemical composition of the Nb x Ti y V m Zr n series refractory multi-principal element alloy is Nb: 0.25≤x≤0.30 at%; Ti: 0.55≤y≤0.60 at%; V: 0.00≤m≤0.05 at%; Zr: 0.10≤n≤0.15 at%, where x + y + m + n = 1. The refractory multi-principal element alloy prepared by the present invention has the advantages of high strength with a single BCC phase structure, the microhardness reaches above 450 HV, and has good thermal stability in the temperature range below 1450 °C; the alloy of the present invention has good thermal stability in a high-temperature environment, can maintain a stable phase structure and excellent mechanical properties during long-term service, and solves the problems of poor thermal stability and decreased mechanical properties of refractory multi-principal element alloys in the medium-temperature range. It has good development prospects in application fields with high strength requirements and good thermal stability. Description of the Drawings

[0021] Figure 1 For the microstructure of the Nb 0.28 Ti 0.58 Zr 0.14 series refractory multi-principal element alloy in Example 1; among them, Figure (a) is the low-magnification metallograph; Figure (b) is the high-magnification metallograph; Figure (c) is the low-magnification scanning; (Figure (d) is the high-magnification scanning);

[0022] Figure 2 For the XRD diffraction pattern of the Nb 0.28 Ti 0.58 Zr 0.14 series refractory multi-principal element alloy in Example 1;

[0023] Figure 3 For the thermal analysis test results of the Nb 0.28 Ti 0.58 Zr 0.14 series refractory multi-principal element alloy in Example 1;

[0024] Figure 4 For Figure 4 Microhardness value comparison chart of Examples 1 - 3;

[0025] Figure 5 For Comparative Example 1 Nb 0.28 Ti 0.58 Zr 0.14 XRD results of refractory multi - principal - element alloy;

[0026] Figure 6 For Comparative Example 2 Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 Metallographic and SEM results of refractory multi - principal - element alloy, where Figure (a) is low - magnification metallography; Figure (b) is high - magnification metallography; Figure (c) is low - magnification scanning; (Figure (d) is high - magnification scanning). Specific embodiments

[0027] The following further elaborates on the present invention in conjunction with specific embodiments, which are explanations of the present invention rather than limitations thereof.

[0028] 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 of 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 scope of protection of the present invention.

[0029] Example 1

[0030] In this example, the chemical composition expression of the refractory multi - principal - element alloy is Nb 0.28 Ti 0.58 Zr 0.14 .

[0031] In this example, Nb 0.28 Ti 0.58 Zr 0.14 The preparation method of the refractory multi - principal - element alloy includes the following steps:

[0032] S1. Convert the molar ratio of each element in the composition into a mass ratio. Weigh and proportion the masses of the pure metal Nb, Ti, and Zr particles with a purity of ≥99.9 wt% according to the atomic percentages for each element required for the designed composition alloy. Use an electronic balance with a precision of 0.1 mg for raw material weighing. The error range during weighing is accurate to ±0.001 g. Proportion the alloy. Table 1 shows the actual proportioning of the high-strength and tough refractory multi-principal element alloy. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr. Ultrasonically clean the polished raw materials, and then place them in a drying oven for drying, which is used for melting and preparing the alloy;

[0033] Table 1 Nb in Example 1 0.28 Ti 0.58 Zr 0.14 Actual proportioning of refractory multi-principal element alloy (g)

[0034]

[0035] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace. Place them in the order of increasing melting points of the pure metals, ensuring that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After completing the placement of the raw materials, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from coming into contact with oxygen during the melting process;

[0036] S3. In the vacuum arc melting process, set the parameters of the arc starting current to 60 A and the melting current to 300 A. After proportioning, use the vacuum arc melting method to repeatedly melt the designed composition alloy 4 times to ensure the uniform distribution of the alloy components;

[0037] S4. After melting is completed, the material is naturally cooled to room temperature in the furnace. After cooling is completed, take it out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition.

[0038] The obtained Nb in this example 0.28 Ti 0.58 Zr 0.14 Microstructure characterization and mechanical property testing of the refractory multi-principal element alloy:

[0039] (1) Microstructure analysis of the alloy

[0040] Samples with dimensions of 8×8×8 mm were cut from the alloy ingots obtained in Example 1 by wire electrical discharge machining. The samples were ground from coarse to fine to 2000# sandpaper, polished using a velvet polishing cloth and 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 using an etching solution composed of 2% hydrofluoric acid, 3% nitric acid, and 95% water, rinsed with alcohol, and dried with cold air for standby. A metallographic microscope and a scanning electron microscope were used to analyze the microstructure of the designed composition alloy.

[0041] (2) Phase structure detection

[0042] From the alloy ingots prepared in Example 1, alloy samples with dimensions of 5 mm×5 mm×3 mm were taken out by wire electrical discharge machining. The samples were ground to a fineness of 1000-mesh sandpaper, then cleaned with alcohol and dried for standby. Subsequently, XRD analysis was performed on the alloy samples, with the scanning angle range set from 20° to 100° and the scanning speed at 5° per minute.

[0043] (3) Density test

[0044] From the alloy ingots melted in Example 1, alloy ingots with dimensions of 3×3×3 mm were cut by wire electrical discharge machining, and the surface was polished until the metallic luster was exposed. The actual density of this high-strength and high-toughness refractory multi-component alloy was measured using the drainage method. The results showed that the density of the high-strength and high-toughness refractory multi-principal element alloy Nb 0.28 Ti 0.58 Zr 0.14 was 6.59 g / cm 3 , showing a relatively obvious advantage in density compared with traditional superalloys.

[0045] (4) Thermal stability analysis

[0046] Disk-shaped samples with dimensions of Φ5×1 mm were cut from the alloy ingots melted in Example 1 by wire electrical discharge machining. The wire electrical discharge machining marks on the sample surface were removed by sanding, and the samples were taken out after 3 min of ultrasonic cleaning in alcohol and dried with cold air. A synchronous thermal analyzer (TG / DSC) was used to perform thermal analysis tests on the alloy. The relevant parameter settings during the test were: the test temperature range was from room temperature to 1450 °C, the heating rate was 10 °C / min, and the cooling rate was 10 °C / min. To prevent oxidation of the alloy during the test from affecting the test results, argon was filled as the protective atmosphere for thermal analysis.

[0047] (5) Hardness test

[0048] Wire cut 8×8×8 mm bulk alloys from the alloy ingots obtained in Example 1, polish the surface until the metallic luster is exposed, and use a microhardness tester to measure the hardness value of the alloy obtained in Example 1. The load is set to 1 kgf and the holding time is set to 10 s. Five hardness tests are performed on the sample surface, and the average hardness of these five tests is taken as the final test result of the alloy microhardness. The high-strength and tough refractory multi-principal element alloy Nb 0.28 Ti 0.58 Zr 0.14 has a microhardness value of 464.2 HV.

[0049] Example 2

[0050] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.26 Ti 0.56 V 0.03 Zr 0.15 .

[0051] In this example, the preparation method of the Nb 0.26 Ti 0.56 V 0.03 Zr 0.15 refractory multi-principal element alloy includes the following steps:

[0052] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the pure metals Nb, Ti, and Zr particles with a purity ≥ 99.9 wt% according to the atomic percentage for the alloy of the designed composition. Use an electronic balance with a precision of 0.1 mg for raw material weighing, and the error range during weighing is accurate to ±0.001 g for alloy proportioning. Remove the oxide layer on the surface of Nb, Ti, V, and Zr using sandpaper, ultrasonically clean the polished raw materials, and place them in a drying oven for drying for use in melting and preparing the alloy;

[0053] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace, and place them in the order of increasing melting points of the pure metals, ensuring that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After completing the placement of the raw materials, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from contacting oxygen during the melting process;

[0054] S3. In the vacuum arc melting process, set the parameters of the arc starting current to 60 A and the melting current to 300 A. After proportioning, use the vacuum arc melting method to repeatedly melt the alloy of the designed composition 4 times to ensure the uniform distribution of the alloy composition;

[0055] S4. After melting is completed, the material is naturally cooled to room temperature in the furnace. After cooling is completed, it is taken out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition.

[0056] The Nb obtained in this embodiment 0.26 Ti 0.56 V 0.03 Zr 0.15 Characterization of the microstructure and mechanical property testing of the refractory multi-principal element alloy:

[0057] The single-phase BCC structure Nb prepared in this embodiment 0.26 Ti 0.56 V 0.03 Zr 0.15 The room temperature hardness of the refractory multi-principal element alloy is 458.8 HV, and no phase transformation occurs from room temperature to 1450 °C.

[0058] Example 3

[0059] The chemical composition expression of the refractory high-entropy alloy in this embodiment is Nb 0.26 Ti 0.58 V 0.02 Zr 0.14 .

[0060] The Nb in this embodiment 0.26 Ti 0.58 V 0.02 Zr 0.14 The preparation method of the refractory multi-principal element alloy includes the following steps:

[0061] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the pure metals Nb, Ti, and Zr particles with a purity ≥ 99.9 wt% according to the atomic percentage for the alloy with the designed composition. Use an electronic balance with a precision of 0.1 mg for raw material weighing. The error range during weighing is accurate to ±0.001 g, and proportion the alloy. 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;

[0062] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace, place them in the order of increasing melting point of the pure metals, ensure that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After the raw material placement is completed, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops to 6.0×10 -3Below Pa. After evacuating the air, argon gas is filled into the furnace cavity as a protective gas to prevent the material from contacting with oxygen during the melting process;

[0063] S3. During the vacuum arc melting process, the parameter settings of the arc starting current of 60 A and the melting current of 300 A are adopted. After the batching is completed, the vacuum arc melting method is used, and the designed composition alloy is repeatedly melted 4 times to ensure the uniform distribution of the alloy components;

[0064] S4. After the melting is completed, the material is naturally cooled to room temperature in the furnace. After the cooling is completed, it is taken out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition.

[0065] The single-phase BCC structure Nb prepared in this embodiment 0.26 Ti 0.58 V 0.02 Zr 0.14 The room temperature hardness of the refractory multi-principal element alloy is 482.8 HV, and no phase transformation occurs at room temperature to 1450 °C.

[0066] Figure 1 For the Nb in Example 1 0.28 Ti 0.58 Zr 0.14 For the microstructure morphology of the refractory multi-principal element alloy, it can be seen under the metallographic microscope that the alloy presents an equiaxed crystal microstructure morphology. Using a scanning electron microscope to further magnify and observe this structure, it can be seen that the interior of the larger-sized equiaxed grains is composed of fine granular phases. Figure 2 For the Nb in Example 1 0.28 Ti 0.58 Zr 0.14 The XRD test analysis results of the refractory multi-principal element alloy, Nb 0.28 Ti 0.58 Zr 0.14 The phase structure of the alloy consists of a BCC single-phase structure. Figure 3 For the thermal analysis test curve of Example 1, there are no obvious endothermic peaks or exothermic peaks on the thermal analysis curve, which indicates that when the temperature is below 1450 °C, the alloy of this composition does not undergo phase transformation or melting behavior, proving its good thermal stability. Figure 4 For Nb 0.28 Ti 0.58 Zr 0.14 、Nb 0.26 Ti 0.56 V 0.03 Zr 0.15 、Nb 0.26 Ti 0.58 V 0.02 Zr 0.14Comparison of the microhardness values of three examples (corresponding to Example 1, Example 2, and Example 3 respectively), and the error bars are in the form of standard deviation. The microhardness values of all three examples are above 450 HV. The examples of the present invention can effectively optimize the hardness of refractory multi-principal element alloys.

[0067] Example 4

[0068] In this example, the chemical composition expression of the refractory high-entropy alloy is Nb 0.30 Ti 0.55 V 0.05 Zr 0.10 .

[0069] In this example, Nb 0.30 Ti 0.55 V 0.05 Zr 0.10 The preparation method of the refractory multi-principal element alloy includes the following steps:

[0070] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the pure metals Nb, Ti, and Zr particles with a purity ≥ 99.9 wt% according to the atomic percentage for the elements required for the designed composition alloy. Use an electronic balance with a precision of 0.1 mg for raw material weighing. The error range during weighing is accurate to ±0.001 g for alloy proportioning. Remove the oxide layer on the surface of Nb, Ti, V, and Zr using sandpaper, ultrasonically clean the polished raw materials, and place them in a drying oven for drying for use in melting and preparing the alloy;

[0071] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace, and place them in the order of increasing melting points of the pure metals, ensuring that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After completing the raw material placement, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from contacting oxygen during the melting process;

[0072] S3. The parameters for the vacuum arc melting process are set with an arc ignition current of 60 A and a melting current of 300 A. After proportioning, use the vacuum arc melting method to repeatedly melt the designed composition alloy 4 times to ensure the uniform distribution of the alloy components;

[0073] S4. After melting is completed, the material is naturally cooled to room temperature in the furnace. After cooling is completed, take it out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition.

[0074] The single-phase BCC-structured Nb prepared in this embodiment 0.30 Ti 0.55 V 0.05 Zr 0.10 The room-temperature hardness of the refractory multi-principal element alloy is 476.8 HV, and no phase transformation occurs from room temperature to 1450 °C.

[0075] Example 5

[0076] The chemical composition expression of the refractory high-entropy alloy in this embodiment is Nb 0.25 Ti 0.60 V 0.03 Zr 0.12 .

[0077] The Nb 0.25 Ti 0.60 V 0.03 Zr 0.12 The preparation method of the refractory multi-principal element alloy includes the following steps:

[0078] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the pure metals Nb, Ti, and Zr particles with a purity ≥ 99.9 wt% according to the atomic percentage for the elements required for the designed composition alloy. Use an electronic balance with a precision of 0.1 mg for raw material weighing, with the error range accurate to ±0.001 g during weighing, and proportion the alloy. Use sandpaper to remove the oxide layer on the surfaces of Nb, Ti, V, and Zr, ultrasonically clean the polished raw materials, and place them in a drying oven for drying for use in melting and preparing the alloy;

[0079] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of a WK-II type non-consumable vacuum melting furnace, place them in the order of increasing melting point of the pure metals, ensure that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After completing the raw material placement, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from contacting oxygen during the melting process;

[0080] S3. The parameters for the vacuum arc melting process are set with an arc starting current of 60 A and a melting current of 300 A. After completing the proportioning, use the vacuum arc melting method to repeatedly melt the designed composition alloy 4 times to ensure the uniform distribution of the alloy composition;

[0081] S4. After the melting is completed, the material is naturally cooled to room temperature in the furnace. After cooling is completed, take it out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition.

[0082] The single-phase BCC-structured Nb prepared in this example 0.25 Ti 0.60 V 0.03 Zr 0.12 The room-temperature hardness of the refractory multi-principal element alloy is 478.4 HV, and no phase transformation occurs from room temperature to 1450 °C.

[0083] Comparative Example 1:

[0084] This Comparative Example 1 provides a dual-phase Nb with the same composition as that in Example 1 but different structure 0.28 Ti 0.58 Zr 0.14 The preparation method is as follows:

[0085] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the pure metal Nb, Ti, and Zr particles with a purity of ≥99.9 wt% according to the atomic percentage for the elements required for the designed composition alloy. Use an electronic balance with a precision of 0.1 mg for raw material weighing. The error range during weighing is accurate to ±0.001 g for alloy proportioning. Remove the oxide layer on the surfaces of Nb, Ti, V, and Zr using sandpaper, ultrasonically clean the polished raw materials, and place them in a drying oven for drying for use in melting and preparing the alloy;

[0086] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of a WK-II type non-consumable vacuum melting furnace, and place them in the order of increasing melting points of the pure metals, ensuring that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After completing the raw material placement, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from contacting oxygen during the melting process;

[0087] S3. The parameters of the vacuum arc melting process are set with an arc starting current of 60 A and a melting current of 300 A. After the proportioning is completed, use the vacuum arc melting method to repeatedly melt the designed composition alloy 4 times to ensure the uniform distribution of the alloy composition;

[0088] S4. After the melting is completed, the material is naturally cooled to room temperature in the furnace. After cooling is completed, take it out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition;

[0089] S5. Comparative Example Nb 0.28 Ti 0.58 Zr 0.14After the refractory multi-principal element alloy is prepared, the as-cast alloy is placed in a box-type resistance furnace for annealing treatment at 1200 °C for 20 h;

[0090] The structure and mechanical property testing methods of the refractory multi-principal element alloy of Comparative Example 1 are the same as those of Example 1. Figure 5 Shows the XRD results of the refractory multi-principal element alloy of Comparative Example Nb 0.28 Ti 0.58 Zr 0.14 ; Figure 6 Shows the XRD results of the refractory multi-principal element alloy of Comparative Example Nb 0.09 Ti 0.37 V0 .37 Zr 0.18 ; and the metallographic and SEM results of the refractory multi-principal element alloy.

[0091] The Nb 0.28 Ti 0.58 Zr 0.14 refractory multi-principal element alloy prepared in this Comparative Example 1 undergoes annealing treatment to precipitate a second phase in the designed composition alloy, transforming into a BCC duplex structure, losing strength compared with the alloy of Example 1, with a microhardness of 302.7 HV. The alloy undergoes a phase transformation at 850 °C, resulting in poor thermal stability in the medium temperature range.

[0092] Comparative Example 2:

[0093] Taking a control experiment as a comparative example, for example, when the reaction temperature is 20 - 50 °C, test schemes corresponding to reaction temperatures outside the range of 20 - 50 can be provided;

[0094] In this Comparative Example 2, refractory high-entropy alloys outside the range are prepared according to the embodiment scheme, and the chemical composition expression is Nb 0.51 Ti 0.12 V 0.06 Zr 0.31 .

[0095] The preparation method of the refractory multi-principal element alloy of this Comparative Example Nb 0.51 Ti 0.12 V 0.06 Zr 0.31 includes the following steps:

[0096] S1. Convert the molar ratio of each element in the composition into a mass ratio, weigh and proportion the masses of the elements required for the designed composition alloy by weighing pure metal Nb, Ti, and Zr particles with a purity ≥ 99.9 wt% according to the atomic percentage. Use an electronic balance with a precision of 0.1 mg for raw material weighing, and the error range during weighing is accurate to ±0.001 g for alloy proportioning. Remove the oxide layer on the surface of Nb, Ti, V, and Zr using sandpaper, ultrasonically clean the polished raw materials, and place them in a drying oven for drying for use in melting and preparing the alloy;

[0097] S2. Place the weighed and processed alloy raw materials into the water-cooled copper crucible of the WK-II type non-consumable vacuum melting furnace, and place them in the order of increasing melting points of pure metals, ensuring that the metal with the lowest melting point is at the bottom of the crucible and the metal with the highest melting point is at the top. At the same time, to ensure the uniformity of the melted alloy ingot, try to lay the metal particles flat. After the raw material placement is completed, close and seal the furnace door, and perform a vacuum pumping operation on the furnace body until the vacuum degree in the furnace cavity drops below 6.0×10 -3 Pa. After vacuum pumping, fill the furnace cavity with argon as a protective gas to prevent the material from contacting oxygen during the melting process;

[0098] S3. In the vacuum arc melting process, set the parameters of the arc ignition current to 60A and the melting current to 300A. After the batching is completed, use the vacuum arc melting method to repeatedly melt the designed composition alloy 4 times to ensure the uniform distribution of the alloy components;

[0099] S4. After the melting is completed, the material is naturally cooled to room temperature in the furnace. After the cooling is completed, take it out of the furnace to obtain a refractory multi-principal element alloy ingot with the required composition;

[0100] The high-strength and tough refractory multi-principal element alloy Nb 0.51 Ti 0.12 V 0.06 Zr 0.31 prepared in this embodiment has a microhardness of 234.6 HV. The single-phase BCC refractory multi-principal element alloy undergoes a phase change at 1080°C and has poor thermal stability.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the specification of this invention herein are only for the purpose of describing specific embodiments and are not intended to limit the invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0102] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention; any ordinary technician in the industry can smoothly implement the present invention as shown in the accompanying drawings of the specification and described above; 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 by using the technical content disclosed above are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and variations made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-strength and heat-resistant 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: 0.25≤x≤0.30at%; Ti: 0.55≤y≤0.60at%; V: 0.00≤m≤0.05at%; Zr: 0.10≤n≤0.15at%, wherein x+y+m+n=1.

2. A high-strength and heat-resistant 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 does not exceed 7g / cm 3 .

3. A high-strength and heat-resistant 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 hardness value of the refractory multi-principal alloy reaches 464.2HV.

4. A high-strength and heat-resistant 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, cooled to room temperature, high-strength and heat-resistant Nb x Ti y V m Zr n It is a refractory multi-principal alloy.

5. A high-strength and heat-resistant 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 heat-resistant 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 heat-resistant 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 heat-resistant 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 heat-resistant 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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