High-temperature-resistant eutectic high-entropy alloy and preparation method and application thereof

Abstract

The invention relates to the technical field of alloy materials, and particularly discloses a high-temperature-resistant eutectic high-entropy alloy and a preparation method and application thereof.The chemical formula of the high-temperature-resistant eutectic high-entropy alloy is MoaTabWcCd, a, b, c and d are atomic ratios of corresponding elements respectively, a is larger than or equal to 27.1 and smaller than or equal to 27.5, b is larger than or equal to 28 and smaller than or equal to 31, c is larger than or equal to 24 and smaller than or equal to 27, d is larger than or equal to 17 and smaller than or equal to 24, and a + b + c + d = 100. The high-temperature-resistant eutectic high-entropy alloy has a complete lamellar eutectic structure, is excellent in high-temperature mechanical property and still keeps excellent strength at the temperature exceeding the use limit (1473K) of a traditional nickel-based high-temperature alloy. According to the present invention, the high-temperature-resistant and high-pressure-resistant ceramic material can respectively maintain the compressive strength of 1476.7 MPa, 773.6 MPa and 281.6 MPa at the high temperatures of 1473K, 1873K and 2273K, and has ultrahigh strength at the room temperature, and the compressive strength at the room temperature is 2.23 GPa. And meanwhile, the high hardness of 1016.8 HV is achieved, and the hardness is about 4.8 times that of 304 stainless steel. The material can be used for preparing ultrahigh-temperature-resistant key hot end parts of the nuclear energy field, the national defense and military field, the aerospace field, high-temperature equipment and gas turbines.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and in particular, to a high-temperature resistant eutectic high-entropy alloy, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of cutting-edge scientific and technological fields such as the nuclear energy field, the national defense and military field, the aerospace field, high-temperature equipment, and gas turbines, there is an urgent need for key hot-end materials with structural stability and high strength under ultra-high temperature extreme conditions. Traditional nickel-based and cobalt-based superalloys have problems such as insufficient high-temperature strength, high-temperature softening, and poor high-temperature structural stability. Their melting points are around 1573K, and the service temperatures mostly do not exceed 1473K, making it difficult to meet the special requirements of key hot-end components.

[0003] To solve the problems of poor high-temperature resistance and low yield strength of traditional alloys, materials scientists have developed a high-entropy alloy system based on the design concept of multi-principal element alloys. High-entropy alloys have more excellent mechanical properties at room temperature and high temperature, wear resistance, corrosion resistance, oxidation resistance, etc. compared with traditional alloys. The refractory high-entropy alloy Nb 25 Mo 25 Ta 25 W 25 first reported by the U.S. Air Force Laboratory in 2011 has far exceeded traditional alloys in terms of yield strength, compressive strength, and fracture strain. However, with the development of science and technology, people's requirements for material properties are getting higher and higher. Refractory high-entropy alloys composed of pure metals alone can no longer meet the application requirements at ultra-high temperatures (≥2073K). Therefore, a new type of refractory high-entropy alloy with higher yield strength, compressive strength, and fracture strain at ultra-high temperatures is needed.

[0004] Therefore, it is necessary to design a new type of refractory high-entropy alloy to solve the problem that the existing refractory high-entropy alloys can no longer meet the application requirements at ultra-high temperatures (≥2073K). Summary of the Invention

[0005] In view of this, the present invention provides a high-temperature resistant eutectic high-entropy alloy, aiming to solve the problem that the existing refractory high-entropy alloys and eutectic high-entropy alloys can no longer meet the application requirements at ultra-high temperatures (≥2073K).

[0006] On the one hand, the present invention provides a high-temperature resistant eutectic high-entropy alloy, whose chemical formula is Mo a Ta b W c C d . a, b, c, and d are the atomic ratios of the corresponding elements, where 27.1 ≤ a ≤ 27.5, 28 ≤ b ≤ 31, 24 ≤ c ≤ 27, 17 ≤ d ≤ 24, and a + b + c + d = 100.

[0007] Furthermore, the Mo a Ta b W c C d The high-temperature resistant eutectic high-entropy alloy is composed of two phases: a high-entropy alloy solid solution phase with a BCC structure and a carbide phase with an HCP structure.

[0008] On the one hand, the present invention also provides a method for preparing a high-temperature resistant eutectic high-entropy alloy, comprising the following steps:

[0009] Weigh the raw materials Mo, Ta, W, and TaC according to the atomic ratio of a:b:c:d, and pre-treat the raw materials Mo, Ta, and W.

[0010] Put the raw materials into a copper crucible of a high-vacuum arc melting furnace equipped with a molecular pump and a mechanical pump, and perform the first melting to obtain a first mixture.

[0011] Wait for the first mixture to cool, then turn it over for the second melting, and then cool and cast the ingot to obtain a second mixture.

[0012] Perform repeated melting on the second mixture, and after cooling, obtain the Mo a Ta b W c C d High-temperature resistant eutectic high-entropy alloy.

[0013] Furthermore, before the first melting, put the titanium ingot into another copper crucible of the high-vacuum arc melting furnace, and melt the titanium ingot for 3 - 5 minutes under the protection of an argon atmosphere.

[0014] Furthermore, the pre-treatment is specifically as follows: Pickle the raw materials Mo, Ta, and W three times with an acid pickling solution, and then clean them with ultrasonic waves; the acid pickling solution is prepared from hydrochloric acid and water with a volume ratio of 1:9; the acid pickling time is 3 minutes; the ultrasonic cleaning time is 5 minutes.

[0015] Furthermore, the specific method for melting the titanium ingot is as follows: Use the mechanical pump to evacuate to 5 Pa, then start the molecular pump, and after the molecular pump speed reaches 27000 r / min, further evacuate to below 5×10 -3 Pa, and then fill with argon to a pressure of 0.05 - 0.06 MPa.

[0016] Furthermore, the first melting and the second melting are specifically as follows: Set the current to 300 - 400 A, start electromagnetic stirring after the raw materials are melted, the magnetic field current of the electromagnetic stirring is 0.7 A, and keep the arc for 4 - 5 minutes.

[0017] Further, the number of times of repeated melting is 5-10 times; the specific melting method is as follows: use a current of 300-400 A to melt the second mixture, and keep the arc for 4-5 minutes after melting. During this period, keep stirring. After cooling and turning over, continue to use a current of 300-400 A for melting, keep the arc for 4-5 minutes after melting, keep stirring during this period, and then cool and cast the ingot after completion.

[0018] Further, when putting the pre-treated raw materials Mo, Ta, W, and TaC into the copper crucible of the high-vacuum arc melting furnace, put them in order from the highest melting point to the lowest melting point of the raw materials. The one with the lowest melting point is placed at the bottom layer, and the one with the highest melting point is placed at the top layer.

[0019] On the other hand, the present invention also proposes an application of a high-temperature-resistant eutectic high-entropy alloy, the Mo a Ta b W c C d The high-temperature-resistant eutectic high-entropy alloy is used to prepare key ultra-high-temperature hot-end components for the nuclear energy field, national defense and military field, aerospace field, high-temperature equipment, and gas turbines.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The Mo a Ta b W c C d The high-temperature-resistant eutectic high-entropy alloy prepared by the present invention has a completely dual-phase associated lamellar eutectic structure. At the same time, the present invention adds carbides with high melting points (the melting point of Ta2C is 3603K) on the refractory high-entropy alloy matrix to in-situ generate a ceramic phase-reinforced composite material, so that the high-temperature mechanical properties of this application are excellent, and it still maintains excellent strength at temperatures exceeding the use limit of traditional nickel-based superalloys (1473K) and above. Even at 2273K, it shows a yield strength of 214.1 MPa and a compressive strength of 281.6 MPa, and the engineering strain > 35%. The yield strength at 1473K is 1085.1 MPa, the compressive strength is 1476.7 MPa, and the fracture strain is 27.5%. The yield strength at 1873K is 727.5 MPa, the compressive strength is 829.3 MPa, and the fracture strain is 17.7%. The yield strength at room temperature is 1.43 GPa, the compressive strength is 2.23 GPa, and the fracture strain is 3.9%. Compared with the earliest reported Nb 25 Mo 25 Ta 25 W 25 Refractory high-entropy alloy, Mo a Ta b W c C dThe plasticity, strength at room temperature, and high-temperature strength of the high-temperature-resistant eutectic high-entropy alloy are all improved, indicating that the effect of using carbides to strengthen the refractory high-entropy alloy matrix is good. Description of the Drawings

[0021] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0022] Figure 1 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 Backscattered SEM image of the high-temperature-resistant eutectic high-entropy alloy.

[0023] Figure 2 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 Flowchart of the preparation method of the high-temperature-resistant eutectic high-entropy alloy.

[0024] Figure 3 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 EPMA-WDS elemental distribution map of the high-temperature-resistant eutectic high-entropy alloy.

[0025] Figure 4 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 XRD pattern of the high-temperature-resistant eutectic high-entropy alloy.

[0026] Figure 5 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 Room-temperature compression engineering stress-strain curve of the high-temperature-resistant eutectic high-entropy alloy.

[0027] Figure 6 Mo provided in Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 Vickers hardness indentation map and Vickers hardness value histogram of the high-temperature-resistant eutectic high-entropy alloy.

[0028] Figure 7 Mo provided for Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 Nanoindentation force-displacement curve of the high-temperature resistant eutectic high-entropy alloy

[0029] Figure 8 Mo provided for Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 1473K compression engineering stress-strain curve diagram of the high-temperature resistant eutectic high-entropy alloy

[0030] Figure 9 Mo provided for Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 1873K compression engineering stress-strain curve diagram of the high-temperature resistant eutectic high-entropy alloy

[0031] Figure 10 Mo provided for Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 2273K compression engineering stress-strain curve diagram of the high-temperature resistant eutectic high-entropy alloy

[0032] Figure 11 Mo provided for Embodiment 1 of the present invention 27.3 Ta 29.3 W 26.0 C 17.4 DSC curve diagram of the high-temperature resistant eutectic high-entropy alloy

[0033] Figure 12 Mo provided for Embodiment 2 of the present invention 27.1 Ta 28.0 W 24.0 C 20.9 Secondary electron SEM image of the high-temperature resistant eutectic high-entropy alloy

[0034] Figure 13 Mo provided for Embodiment 2 of the present invention 27.1 Ta 28.0 W 24.0 C 20.9 XRD pattern of the high-temperature resistant eutectic high-entropy alloy

[0035] Figure 14 Mo provided for Embodiment 2 of the present invention 27.1 Ta 28.0 W 24.0 C20.9 Engineering stress-strain curve of the high-temperature resistant eutectic high-entropy alloy at room temperature.

[0036] Figure 15 Mo provided in Embodiment 2 of the present invention 27.1 Ta 28.0 W 24.0 C 20.9 DSC curve of the high-temperature resistant eutectic high-entropy alloy. Detailed implementation manners

[0037] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0038] With the rapid development of cutting-edge technology fields such as the nuclear energy field, the national defense and military field, the aerospace field, high-temperature equipment, and gas turbines, there is an urgent need for key hot-end materials with structural stability and high strength under ultra-high temperature extreme conditions. Traditional nickel-based and cobalt-based superalloys have problems such as insufficient high-temperature strength, high-temperature softening, and poor high-temperature structural stability. The melting points of nickel-based and cobalt-based superalloys are around 1573K, and the service temperatures mostly do not exceed 1473K, making it difficult to meet the special requirements of key hot-end components.

[0039] To solve the problems of poor high-temperature resistance and low yield strength of traditional alloys, materials scientists have developed a high-entropy alloy system based on the design concept of multi-principal element alloys. High-entropy alloys have more excellent mechanical properties at room temperature and high temperature, wear resistance, corrosion resistance, oxidation resistance, etc. compared with traditional alloys. The refractory high-entropy alloy of Nb 25 Mo 25 Ta 25 W 25 first reported by the US Air Force Laboratory in 2011 has far exceeded traditional alloys in terms of yield strength, compressive strength, and fracture strain. However, with the development of science and technology, people's requirements for material properties are getting higher and higher. The refractory high-entropy alloy composed of pure metals alone can no longer meet the application requirements at ultra-high temperatures (≥2073K). Therefore, a new type of refractory high-entropy alloy with higher yield strength, compressive strength, and fracture strain at ultra-high temperatures is needed. Therefore, it is necessary to design a new type of refractory high-entropy alloy to solve the problem that the existing refractory high-entropy alloys can no longer meet the needs.

[0040] On the one hand, in some embodiments of the present invention, a high-temperature resistant eutectic high-entropy alloy has a chemical formula of Mo a Ta b W c C d , where 27.1 ≤ a ≤ 27.5, 28 ≤ b ≤ 31, 24 ≤ c ≤ 27, 17 ≤ d ≤ 24, and a + b + c + d = 100.

[0041] Specifically, in the present invention, the value of a is preferably 27.3, the value of b is preferably 29.3, the value of c is preferably 26, and the value of d is preferably 17.4.

[0042] In some embodiments of the present invention, the Mo a Ta b W c C d high-temperature resistant eutectic high-entropy alloy is composed of two phases: a high-entropy alloy solid solution phase with a BCC structure and a carbide phase with an HCP structure.

[0043] On the other hand, in some embodiments of the present application, a method for preparing a high-temperature resistant eutectic high-entropy alloy is provided, including the following steps:

[0044] Weigh the raw materials Mo, Ta, W, and TaC according to the atomic ratio of a:b:c:d, and pretreat the raw materials Mo, Ta, and W;

[0045] Put the raw materials into a copper crucible of a high-vacuum arc melting furnace equipped with a molecular pump and a mechanical pump, and perform the first melting to obtain a first mixture;

[0046] Wait for the first mixture to cool, after cooling, turn it over for the second melting, stir for 2 minutes after melting, and then cool and cast to obtain a second mixture;

[0047] Repeatedly melt the second mixture, and after cooling, obtain the Mo a Ta b W c C d high-temperature resistant eutectic high-entropy alloy.

[0048] Specifically, the raw materials Mo, Ta, and W are single-element particles of each element with a purity ≥ 99.9 wt.%, and the raw material TaC is a powder with a purity ≥ 99.5 wt.%.

[0049] In some embodiments of the present application, before the first melting, put a titanium ingot into another copper crucible of the high-vacuum arc melting furnace, and first melt the titanium ingot for 3 - 5 minutes under the protection of an argon atmosphere; the melting time is preferably 4 minutes.

[0050] It is understandable that melting the titanium ingot for 3 - 5 minutes under the protection of an argon atmosphere can effectively absorb the remaining oxygen and prevent the residual oxygen from affecting the subsequent Mo. a Ta b W c C d Preparation of a high - temperature - resistant eutectic high - entropy alloy.

[0051] In some embodiments of the present application, the pretreatment is specifically as follows: pickling the raw materials Mo, Ta, and W three times with an acid pickling solution, and then cleaning with ultrasonic waves; the acid pickling solution is prepared from hydrochloric acid and water with a volume ratio of 1:9; the pickling time is 3 minutes; the ultrasonic cleaning time is 5 minutes.

[0052] It is understandable that pickling and ultrasonic cleaning of the raw materials are mainly to remove raw material impurities and surface oxide layers.

[0053] In some embodiments of the present application, the specific method for melting the titanium ingot is as follows: using a mechanical pump to evacuate to 5 Pa, then starting the molecular pump, and after the molecular pump speed reaches 27000 r / min, further evacuating to below 5×10 -3 Pa, and then filling with argon to a pressure of 0.05 - 0.06 MPa.

[0054] It is understandable that when filling with argon, observe the pressure gauge at all times, and stop immediately when the pressure is between 0.05 - 0.06 MPa.

[0055] In some embodiments of the present application, the first melting and the second melting are specifically as follows: setting the current to 300 - 400 A, starting electromagnetic stirring after the raw materials are melted, the magnitude of the electromagnetic stirring magnetic field current is 0.7 A, and keeping the arc for 4 - 5 minutes; the current is preferably 350 A, and the arc - keeping time is preferably 5 minutes.

[0056] It is understandable that maintaining the arc for a certain period of time allows elements to have sufficient time for diffusion and mixing, thereby improving the uniformity of the alloy composition and reducing the phenomenon of composition segregation, which is crucial for obtaining alloy materials with stable and consistent properties; keeping the arc for 4 - 5 minutes allows impurities and gases to have sufficient time to volatilize and be discharged out of the furnace, thereby improving the purity of the alloy and reducing the adverse effects of impurities on the alloy properties; appropriately extending the arc action time helps to stabilize the solidification structure of the alloy. During this period, the liquid alloy can make some microstructure adjustments and optimizations in a relatively stable high - temperature environment, making the solidification process of the alloy more uniform and orderly, thereby obtaining a more ideal microstructure, and further improving the mechanical properties and high - temperature resistance of the alloy.

[0057] In some embodiments of the present application, the number of times of repeated melting is 5 - 10 times; the specific method of melting is as follows: use a current of 300 - 400 A to melt the second mixture, and after melting, the electric arc continues to be maintained for 4 - 5 minutes, with stirring maintained during this period. After completion, it is cooled and flipped, and then melted again using a current of 300 - 400 A. After melting, the electric arc continues to be maintained for 4 - 5 minutes, with stirring maintained during this period. After completion, it is cooled and ingoted; the current is preferably 350 A, and the electric arc maintenance time is preferably 5 minutes.

[0058] It can be understood that as the number of melting times increases, the solidification process of the alloy becomes more uniform, which can refine the grains. During the cooling process after each melting, due to repeated thermal cycles, the grain growth mode of the alloy will change, which is more conducive to forming a fine and uniform grain structure, thereby improving the strength, toughness, and high-temperature resistance of the alloy, etc.

[0059] In some embodiments of the present application, when putting the pre-treated raw materials Mo, Ta, W, and TaC into the copper crucible of the high-vacuum arc melting furnace, they are put in order from the highest melting point to the lowest melting point of the raw materials. The one with the lowest melting point is placed at the bottom layer, and the one with the highest melting point is placed at the top layer.

[0060] It can be understood that when the raw materials are placed from the highest melting point to the lowest melting point, during the melting process, the raw materials with higher melting points are heated first. When starting to melt, the high-melting-point raw materials located at the upper layer are first heated and melted, and the molten metal after their melting will gradually flow downward under the action of gravity. Subsequently, the raw materials with slightly lower melting points are melted in turn. This order can make the raw materials with different melting points melt and mix better in sequence, which is conducive to improving the quality of the alloy. At the same time, when the raw materials are placed in the order of melting points, during the melting process, the raw materials with different melting points melt and fuse at different stages, which is conducive to discharging the gas impurities in the raw materials in a high-vacuum environment.

[0061] On the other hand, in some embodiments of the present application, the high-temperature resistant eutectic high-entropy alloy is used to prepare key ultra-high-temperature hot-end components for the nuclear energy field, national defense and military field, aerospace field, high-temperature equipment, and gas turbines.

[0062] Example 1

[0063] S1. Weigh the raw materials Mo, Ta, W, and TaC according to the atomic ratio of 27.3:29.3:26.0:17.4. Pickle the weighed Mo, Ta, and W particles 3 times with an acid cleaning solution prepared from hydrochloric acid and water with a volume ratio of 1:9 for 3 minutes each time, and then use ultrasonic cleaning for 5 minutes.

[0064] S2. Place the raw materials Mo, Ta, W, and TaC into the copper crucible of a high-vacuum arc melting furnace equipped with a molecular pump and a mechanical pump in descending order of melting point. The one with the lowest melting point is placed at the bottom layer, and the one with the highest melting point is placed at the top layer;

[0065] S3. Place the titanium ingot into another copper crucible of the high-vacuum arc melting furnace. Use the mechanical pump to evacuate to 5 Pa, then start the molecular pump. After the molecular pump speed reaches 27000 r / min, further evacuate to below 5×10 -3 Pa, and then fill with argon to a pressure of 0.05 - 0.06 MPa and first melt the titanium ingot for 3 minutes;

[0066] S4. After the melting of the titanium ingot is completed, use a current of 300 A to melt the raw materials Mo, Ta, W, and TaC. Keep the arc for 4 minutes after the raw materials are fully melted, and continuously stir during this period to obtain the first mixture;

[0067] S5. Wait for the first mixture to cool and then flip it. Then use a current of 300 A to melt it again and keep the arc for 4 minutes, continuously stir during this period, and obtain the second mixture after cooling and casting the ingot;

[0068] S6. Use a current of 300 - A to melt the second mixture. Keep the arc for 4 minutes after melting, and keep stirring during this period. After completion, cool and flip, and continue to melt using a current of 300 A. Keep the arc for 4 minutes after melting, and keep stirring during this period. After completion, cool and cast the ingot; Repeat this step 5 times to obtain the Mo 27.3 Ta 29.3 W 26.0 C 17.4 high-temperature resistant eutectic high-entropy alloy.

[0069] Example 2

[0070] S1. Weigh the raw materials Mo, Ta, W, and TaC according to the atomic ratio of 27.1:28.0:24.0:20.9. Pickle the weighed Mo, Ta, and W particles 3 times with an acid pickling solution prepared from hydrochloric acid and water with a volume ratio of 1:9 for 3 minutes each time, and then use ultrasonic cleaning for 5 minutes;

[0071] S2. Place the raw materials Mo, Ta, W, and TaC into the copper crucible of a high-vacuum arc melting furnace equipped with a molecular pump and a mechanical pump in descending order of melting point. The one with the lowest melting point is placed at the bottom layer, and the one with the highest melting point is placed at the top layer;

[0072] S3. Place the titanium ingot into another copper crucible of the high-vacuum arc melting furnace. Use the mechanical pump to evacuate to 5 Pa, then start the molecular pump. After the molecular pump speed reaches 27000 r / min, further evacuate to below 5×10 -3Below Pa, then argon is filled until the pressure reaches 0.05 - 0.06 MPa, and then the titanium ingot is melted for 3 minutes first;

[0073] S4. After the melting of the titanium ingot is completed, the raw materials Mo, Ta, W, and TaC are melted using a current of 350 A. After the raw materials are fully melted, the electric arc is maintained for 5 minutes, and stirring is continuously carried out during this period to obtain the first mixture;

[0074] S5. After waiting for the first mixture to cool, it is flipped, and then it is melted again using a current of 350 A, and the electric arc is maintained for 5 minutes. Stirring is continuously carried out during this period, and after cooling the ingot, the second mixture is obtained;

[0075] S6. After waiting for the second mixture to cool, the second mixture is melted using a current of 350 A. After melting, the electric arc is continued to be maintained for 5 minutes, and stirring is maintained during this period. After completion, it is cooled and flipped, and melting is continued using a current of 350 A. After melting, the electric arc is continued to be maintained for 5 minutes, and stirring is maintained during this period. After completion, it is cooled and the ingot is cast; this step is repeated 8 times to obtain the Mo 27.1 Ta 28.0 W 24.0 C 20.9 High-temperature resistant eutectic high-entropy alloy.

[0076] Effect test

[0077] For the Mo 27.3 Ta 29.3 W 26.0 C 17.4 High-temperature resistant eutectic high-entropy alloy prepared in Example 1 is subjected to backscattered SEM image detection, and the test results are as Figure 1 shown, and the results show that the alloy has a complete eutectic structure.

[0078] For the Mo 27.3 Ta 29.3 W 26.0 C 17.4 High-temperature resistant eutectic high-entropy alloy prepared in Example 1 is subjected to EPMA-WDS element distribution detection, and the detection results are as Figure 3 shown, Mo 27.3 Ta 29.3 W 26.0 C 17.4 has a complete eutectic structure, and the light gray phase and the dark gray phase show a lamellar distribution. The light gray phase is mainly composed of Ta and C, while the dark gray phase is rich in Mo and W.

[0079] For the Mo 27.3 Ta 29.3 W 26.0 C 17.4 High-temperature resistant eutectic high-entropy alloy prepared in Example 1 is subjected to XRD pattern detection, and the results are as Figure 4 shown, Mo27.3 Ta 29.3 W 26.0 C 17.4 The high-temperature resistant eutectic high-entropy alloy is composed of two phases: a high-entropy alloy solid solution phase with a BCC structure and a carbide phase with an HCP structure.

[0080] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 The high-temperature resistant eutectic high-entropy alloy was subjected to room-temperature compression engineering stress testing, and the test results are as Figure 5 shown. For Mo 27.3 Ta 29.3 W 26.0 C 17.4 the high-temperature resistant eutectic high-entropy alloy has a yield strength of 1.43 GPa, a compressive strength of 2.23 GPa, and a fracture strain of 3.9% at room temperature.

[0081] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 the high-temperature resistant eutectic high-entropy alloy was subjected to Vickers hardness testing. There were 15 test points, evenly distributed on the alloy surface. The results are shown in Table 1:

[0082] Table 1 Vickers hardness test results of the Mo 27.3 Ta 29.3 W 26.0 C 17.4 high-temperature resistant eutectic high-entropy alloy

[0083]

[0084]

[0085] From Table 1, it can be obtained that for Mo 27.3 Ta 29.3 W 26.0 C 17.4 the high-temperature resistant eutectic high-entropy alloy has a high hardness with an average value of 1016.8 HV. The indentation pattern and the bar chart of Vickers hardness values are as Figure 6 shown, and the hardness is about 4.8 times that of 304 stainless steel (hardness 210.0 HV).

[0086] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 the high-temperature resistant eutectic high-entropy alloy was subjected to nanoindentation testing, and the test results are as Figure 7 shown. For Mo 27.3 Ta 29.3 W26.0 C 17.4 The BCC phase of the high-temperature resistant eutectic high-entropy alloy has a high hardness of 10.8 GPa, and the HCP phase has a high hardness of 22.0 GPa.

[0087] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 The compression engineering stress of the high-temperature resistant eutectic high-entropy alloy was detected at 1473 K, and the detection results are as Figure 8 shown. For Mo 27.3 Ta 29.3 W 26.0 C 17.4 The yield strength of the high-temperature resistant eutectic high-entropy alloy at 1473 K is 1085.1 MPa, the compressive strength is 1476.7 MPa, and the fracture strain is 27.5%.

[0088] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 The compression engineering stress of the high-temperature resistant eutectic high-entropy alloy was detected at 1873 K, and the detection results are as Figure 9 shown. For Mo 27.3 Ta 29.3 W 26.0 C 17.4 The yield strength of the high-temperature resistant eutectic high-entropy alloy at 1873 K is 652.5 MPa, the compressive strength is 773.6 MPa, and the fracture strain is 17.7%.

[0089] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 The compression engineering stress of the high-temperature resistant eutectic high-entropy alloy was detected at 2273 K, and the detection results are as Figure 10 shown. For Mo 27.3 Ta 29.3 W 26.0 C 17.4 The yield strength of the high-temperature resistant eutectic high-entropy alloy at 2273 K is 214.1 MPa, the compressive strength is 281.6 MPa, and the fracture strain > 35%.

[0090] For the Mo prepared in Example 1 27.3 Ta 29.3 W 26.0 C 17.4 The DSC detection was carried out on the high-temperature resistant eutectic high-entropy alloy, and the detection results are as Figure 11 shown. For Mo 27.3 Ta29.3 W 26.0 C 17.4 The DSC curve of the high-temperature resistant eutectic high-entropy alloy shows a nearly straight line, confirming that the crystal structure of the alloy is stable in the temperature range from room temperature to 1723 K and no phase transformation occurs.

[0091] For the Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy, secondary electron SEM images were taken. The test results are as Figure 12 shown, indicating that the alloy is composed of eutectic structure and primary phase.

[0092] For the Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy, XRD patterns were detected. The results are as Figure 13 shown. The Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy is composed of two phases: a high-entropy alloy solid solution phase with a BCC structure and a carbide phase with an HCP structure.

[0093] For the Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy, room temperature compressive engineering stress was detected. The test results are as Figure 14 shown. The Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy has a yield strength of 1.04 GPa, a compressive strength of 1.15 GPa, and a fracture strain of 1.3% at room temperature.

[0094] For the Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy, DSC was detected. The test results are as Figure 15 shown. The Mo 27.1 Ta 28.0 W 24.0 C 20.9 The DSC curve of the high-temperature resistant eutectic high-entropy alloy shows a nearly straight line, confirming that the crystal structure of the alloy is stable in the temperature range from room temperature to 1723 K and no phase transformation occurs.

[0095] The Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy prepared in Example 1 was subjected to Vickers hardness testing. There were 15 test points, evenly distributed on the surface of the alloy. The results are shown in Table 2:

[0096] Table 2 Mo 27.1 Ta 28.0 W 24.0 C 20.9 Vickers hardness test results of the high-temperature resistant eutectic high-entropy alloy

[0097]

[0098]

[0099] From Table 2, it can be obtained that the Mo 27.1 Ta 28.0 W 24.0 C 20.9 high-temperature resistant eutectic high-entropy alloy has a high hardness with an average value of 1103.7 HV, and the hardness is about 5.3 times that of 304 stainless steel (hardness 210.0 HV).

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific embodiments of the present invention, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A high temperature resistant eutectic high entropy alloy, characterized in that: Its chemical formula is Mo a Ta b W c C d , a, b, c, and d are the atomic ratios of the corresponding elements, where 27.1≤a≤27.5, 28≤b≤31, 24≤c≤27, 17≤d≤24, and a+b+c+d=100.

2. The high temperature resistant eutectic high entropy alloy according to claim 1, characterized in that: The Mo a Ta b W c C d The high temperature resistant eutectic high entropy alloy is composed of two phases: a high entropy alloy solid solution phase with a BCC structure and a carbide phase with a HCP structure.

3. A method for preparing a high temperature resistant eutectic high entropy alloy as claimed in claim 1, characterized in that: The following steps are involved: Weigh raw materials Mo, Ta, W and TaC according to the atomic ratio of a:b:c:d, and pretreat the raw materials Mo, Ta and W; Putting the raw materials into a copper crucible of a high vacuum arc melting furnace equipped with a molecular pump and a mechanical pump, performing a first melting, and obtaining a first mixture; Waiting for the first mixture to cool, flipping it over after cooling to perform a second melting, and then cooling the ingot to obtain a second mixture; The second mixture is repeatedly melted and cooled to obtain the Mo a Ta b W c C d High temperature resistant eutectic high entropy alloy.

4. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 3, characterized in that: Before the first melting, the titanium ingot is placed in another copper crucible of the high vacuum arc melting furnace and melted for 3-5 minutes under the protection of argon atmosphere.

5. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 3, characterized in that: The pretreatment is specifically as follows: the raw materials Mo, Ta, and W are pickled three times with a pickling solution, and then cleaned with ultrasound; the pickling solution is composed of hydrochloric acid and water in a volume ratio of 1:9; the pickling time is 3 minutes; and the ultrasonic cleaning time is 5 minutes.

6. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 4, characterized in that: The specific method of melting the titanium ingot is: using a mechanical pump to evacuate to 5Pa, then starting the molecular pump, and after the molecular pump speed reaches 27000r / min, further evacuating to 5×10 -3 Pa, and then fill with argon to a pressure of 0.05-0.06MPa.

7. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 3, characterized in that: The first melting and the second melting are specifically as follows: the current is set to 300-400A, electromagnetic stirring is started after the raw material is melted, the electromagnetic stirring current is 0.7A, and the arc is maintained for 4-5 minutes.

8. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 3, characterized in that: The number of repeated smelting is 5-10 times; the specific smelting method is: use a current of 300-400A to melt the second mixture, and the arc is maintained for 4-5 minutes after melting, stirring is maintained during the period, and after the end, the mixture is cooled and turned over, and then the current of 300-400A is continued to be melted, and the arc is maintained for 4-5 minutes after melting, stirring is maintained during the period, and the ingot is cooled after the end.

9. The method for preparing a high temperature resistant eutectic high entropy alloy according to claim 3, characterized in that: When the pretreated raw materials Mo, Ta, W and TaC are placed in the copper crucible of the high vacuum arc melting furnace, the raw materials are placed in order from high to low according to their melting points, with the lowest melting point placed at the bottom layer and the highest melting point placed at the top layer.

10. An application of the high temperature resistant eutectic high entropy alloy according to any one of claims 1 to 8, characterized in that: The Mo a Ta b W c C d High-temperature resistant eutectic high-entropy alloys are used to prepare ultra-high-temperature resistant key hot-end components in the nuclear energy field, national defense and military field, aerospace field, high-temperature equipment, and gas turbines.

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