Refractory high-entropy alloy with both performance improvement and cost reduction and preparation method of refractory high-entropy alloy

Abstract

The invention discloses a refractory high-entropy alloy with both performance improvement and cost reduction and a preparation method of the refractory high-entropy alloy, and relates to a refractory high-entropy alloy and a preparation method of the refractory high-entropy alloy, and the chemical formula of the refractory high-entropy alloy is HfaNbbTicZrd. Wherein b = c = d, and the atomic percentage is 0 < = a < = 25.0, 20.0 < = b < = 35.0, 20.0 < = c < = 35.0, and 20.0 < = d < = 35.0. According to the invention, the purposes of improving the strength and plasticity of the alloy and reducing the cost are achieved mainly by carrying out reduced alloying on the Hf element. The alloy is prepared through a simple vacuum arc melting technology, subsequent heat treatment and thermal deformation optimization are not needed, according to a solid solution strengthening mechanism, the yield strength of the as-cast HfaNbbTicZrd alloy is improved by 11%, the ductility is improved by 27%, and meanwhile the cost is reduced by 60%. The method is applied to the field of metal materials and preparation thereof.

Description

Technical Field

[0001] The present invention relates to a refractory high-entropy alloy with improved performance and reduced cost and a preparation method thereof. Background Art

[0002] Traditional alloys generally use one or two elements as the matrix, and add a small amount of metal or non-metal elements to change the structure and performance. With the rapid development of aerospace, nuclear reactors, and military industries, the performance of traditional alloys has been difficult to meet the needs of products. Therefore, the concept of refractory high-entropy alloys emerged. They are mainly composed of 5 or more elements. Due to their unique design concept, refractory high-entropy alloys can balance good strength, hardness, plasticity, and wear resistance, and have broad application potential.

[0003] Poor room-temperature plasticity limits the application range of refractory high-entropy alloys. Currently, there are very few refractory high-entropy alloy systems with room-temperature plasticity, including HfNbTaTiZr, NbTiVZr, TiVNbHf, and HfNbTiZr. Therefore, how to improve room-temperature plasticity is a crucial issue. The co-addition of multiple elements has been widely explored in scientific research. However, due to the differences in melting points and densities of different elements, it may affect the uniformity of the alloy, resulting in serious composition segregation in large-scale traditional melting, and the large number of element types will lead to too high cost of the alloy. But traditional alloying methods will reduce plasticity while increasing strength, and it is difficult to achieve the synergistic improvement of strength and plasticity. Moreover, the constituent elements of refractory high-entropy alloys are usually mainly high-density elements, which leads to generally high densities of refractory high-entropy alloys. The high density limits their application in fields such as aerospace that require lightweight materials. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of poor plasticity, high price, and high density of existing refractory high-entropy alloys that affect their application in the field of lightweight materials, and to propose a refractory high-entropy alloy with improved performance and reduced cost and a preparation method thereof.

[0005] The chemical formula of a refractory high-entropy alloy with improved performance and reduced cost according to the present invention is Hf a Nb b Ti c Zr d , with atomic percentages of 0≤a≤25.0%, 20.0%≤b≤35.0%, 20.0%≤c≤35.0%, 20.0%≤d≤35.0%, where a + b + c + d = 100% and b = c = d.

[0006] The preparation method of a refractory high-entropy alloy with improved performance and reduced cost according to the present invention is carried out according to the following steps:

[0007] 1. According to the chemical formula Hf a Nb b Ti c Zr d , weigh the raw materials according to the atomic ratio;

[0008] 2. Put the raw materials into the crucible of a non-consumable vacuum melting furnace, evacuate and then introduce argon, and then carry out vacuum arc melting, and then cool the furnace to obtain an alloy ingot;

[0009] 3. After repeatedly melting and cooling the alloy ingot, the refractory high-entropy alloy is obtained.

[0010] The present invention provides a preparation method for dealloying the Hf element, which enhances the solid solution strengthening effect by reducing the content of the Hf element, so as to achieve the purpose of reducing the density and price of the alloy while improving the strength and plasticity.

[0011] The present invention has the following beneficial effects:

[0012] 1. The mixing enthalpy between the four elements of Hf, Nb, Ti, and Zr selected in the present invention is small, and it is relatively easy to form a single-phase BCC solid solution, reducing the formation of hard and brittle phases such as the Laves phase, thereby improving plasticity.

[0013] 2. Hf a Nb b Ti c Zr d The alloy contains high-melting-point elements and has the potential for high-temperature applications.

[0014] 3. By reducing the Hf content, the effects of solid solution strengthening and lattice distortion are achieved, and when there is no Hf, there is a nano-scale ordered structure in the alloy that hinders the movement of dislocations, thereby improving the strength of the alloy.

[0015] 4. The Hf element has a large density and is expensive. The Hf a Nb b Ti c Zr d series alloy achieves the effect of improving the strength and plasticity while significantly reducing the density and cost by reducing the content of the Hf element, expanding its application in the field of lightweight materials.

[0016] 5. The present invention is prepared by a simple vacuum arc melting technology, without subsequent heat treatment and hot deformation optimization. According to the solid solution strengthening mechanism, the yield strength of the as-cast Hf 0 (NbTiZr) 100 alloy is higher than that of Hf 25 (NbTiZr) 75It has increased by 11%, the elongation has increased by 27%, and at the same time the cost has been reduced by 60%. Compared with other melting technologies, this method has low cost, simple process, short preparation cycle, can ensure the uniformity of alloy composition, high safety, and strong operability. Description of the Drawings

[0017] Figure 1 For Hf in Examples 1 to 6 a Nb b Ti c Zr d X-ray diffraction pattern of the refractory high-entropy alloy;

[0018] Figure 2 For Hf in Examples 1 to 6 a Nb b Ti c Zr d Microstructure diagram of the refractory high-entropy alloy;

[0019] Figure 3 For Hf in Examples 1 to 6 a Nb b Ti c Zr d EDS diagram of the refractory high-entropy alloy;

[0020] Figure 4 For Hf in Example 6 0 (NbTiZr) 100 TEM diagram of the refractory high-entropy alloy;

[0021] Figure 5 For Hf in Examples 1 to 6 a Nb b Ti c Zr d Tensile mechanical property diagram of the refractory high-entropy alloy. Detailed Implementation Modes

[0022] The technical solution of the present invention is not limited to the specific implementation modes listed below, and also includes any combination between the specific implementation modes.

[0023] Detailed Implementation Mode 1: The chemical formula of a refractory high-entropy alloy with both performance improvement and cost reduction in this implementation mode is Hf a Nb b Ti c Zr d , and in atomic percentage, 0≤a≤25.0%, 20.0%≤b≤35.0%, 20.0%≤c≤35.0%, 20.0%≤d≤35.0%, where a + b + c + d = 100% and b = c = d.

[0024] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the chemical formula of the refractory high-entropy alloy is Hf 25 (NbTiZr) 75 , where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as Specific Embodiment 1.

[0025] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the chemical formula of the refractory high-entropy alloy is Hf 20 (NbTiZr) 80 , where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as Specific Embodiment 1 or 2.

[0026] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that the chemical formula of the refractory high-entropy alloy is Hf 15 (NbTiZr) 85 , where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as any one of Specific Embodiments 1 to 3.

[0027] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that the chemical formula of the refractory high-entropy alloy is Hf 10 (NbTiZr) 90 , where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as any one of Specific Embodiments 1 to 4.

[0028] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that the chemical formula of the refractory high-entropy alloy is Hf 5 (NbTiZr) 95 , where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as any one of Specific Embodiments 1 to 5.

[0029] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that the chemical formula of the refractory high-entropy alloy is NbTiZr, where Nb, Ti, and Zr are in equiatomic ratio. Others are the same as any one of Specific Embodiments 1 to 6.

[0030] Specific Embodiment 8: The preparation method of a refractory high-entropy alloy with both performance improvement and cost reduction in this embodiment is carried out according to the following steps:

[0031] 1. According to the chemical formula Hf a Nb b Ti c Zr d, the raw materials are weighed according to the atomic percentages of 0 ≤ a ≤ 25.0, 20.0 ≤ b ≤ 35.0, 20.0 ≤ c ≤ 35.0, 20.0 ≤ d ≤ 35.0, where a + b + c + d = 100 and b = c = d;

[0032] II. Put the raw materials into the crucible of a non-consumable vacuum melting furnace, evacuate the vacuum and then introduce argon, and then carry out vacuum arc melting, and then cool the furnace to obtain an alloy ingot;

[0033] III. The refractory high-entropy alloy is obtained after the alloy ingot is repeatedly melted and cooled.

[0034] Specific Embodiment Nine: The difference between this embodiment and Specific Embodiment Eight is that: in Step II, the vacuum in the furnace is pumped to 3×10 -3 Pa, and then argon is introduced to 50 Pa. Others are the same as Specific Embodiment Eight.

[0035] Specific Embodiment Ten: The difference between this embodiment and Specific Embodiment Eight or Nine is that: in Step III, the alloy ingot is repeatedly melted 6 times. Others are the same as Specific Embodiment Eight or Nine.

[0036] The following examples are used to verify the beneficial effects of the present invention:

[0037] Example 1

[0038] A refractory high-entropy alloy that combines performance improvement and cost reduction has the chemical formula Hf 25 (NbTiZr) 75 , where Nb, Ti and Zr are in equal atomic ratios. The specific preparation steps are as follows:

[0039] (1) According to the chemical formula Hf 25 (NbTiZr) 75 , convert it into a mass ratio according to the atomic ratio and weigh the elemental metals. The mass ratio of different elements is Hf:Nb:Ti:Zr = 52.18:27.16:13.99:26.67. The total weight is weighed as 120 g, and the mass of each element is accurate to two decimal places. Among them, the Hf content is 52.18 g, accounting for 43.48% of the total mass;

[0040] (2) Put the raw materials into the crucible of a non-consumable vacuum melting furnace, and put 50 g of pure Ti in one crucible;

[0041] (3) Pump the vacuum in the furnace to 3×10 -3After reaching 50 Pa, argon is introduced until the pressure reaches 50 Pa. Then, melting begins. First, Ti is melted to consume the remaining oxygen in the furnace. The alloy ingot is melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, the output current of the power supply increases by 50 A every 15 s during the heating process, rising to 550 A until the raw materials are completely melted, and then maintaining for 15 s. After cooling, the next melting is carried out. At the end of the last melting, during the cooling process, the output current of the power supply decreases by 50 A every 15 s until the output current drops to 0 A.

[0042] X-ray diffraction experiments were carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results in, it can be known that the alloy is composed of a BCC phase. Microstructure observation was carried out on the high-entropy alloy prepared in this example, as shown in Figure 2 . The microstructure of Hf 25 (NbTiZr) 75 mainly shows a dendritic structure. According to the BSE imaging principle and the melting point differences between alloying elements, it can be inferred that the dendritic part mainly consists of elements Hf and Nb with large atomic numbers and high melting points, and the interdendritic part mainly consists of elements Ti and Zr with relatively small atomic numbers and low melting points. This conclusion can also be obtained from the Figure 3 EDS diagram. Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as shown in Figure 3 . It can be obtained that the tensile yield strength of this composition of refractory high-entropy alloy is 652 MPa, and the elongation after fracture is 11%. According to formula (1), the density of the alloy can be calculated as 8.39 g / cm 3 . Where c i is the atomic ratio, and A i is the relative atomic mass.

[0043]

[0044] Example 2

[0045] The chemical formula of a refractory high-entropy alloy with both improved performance and reduced cost is Hf 20 (NbTiZr) 80 , where Nb, Ti, and Zr have equal atomic ratios. The specific preparation steps are as follows:

[0046] (1) According to the chemical formula Hf 20 (NbTiZr) 80 , the elemental metals are weighed according to the conversion of the atomic ratio to the mass ratio. The mass ratios of different elements are Hf:Nb:Ti:Zr = 43.91:30.47:15.70:29.92. The total weight is weighed as 120 g, and the mass of each element is accurate to two decimal places. Among them, the Hf content is 52.18 g, accounting for 36.59% of the total mass;

[0047] (2) Put the raw materials into the crucible of a non-consumable vacuum melting furnace, and put 50 g of pure Ti in one crucible;

[0048] (3) After evacuating the furnace to a vacuum of 3×10 -3 Pa, introduce argon to 50 Pa. Then start melting. First, melt Ti to consume the remaining oxygen in the furnace. The alloy ingot is melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, the output current of the power supply increases by 50 A every 15 s during the heating process, increasing to 550 A until the raw materials are completely melted, and it is maintained for 15 s. After cooling, the next melting is carried out; at the end of the last melting, during the cooling process, the output current of the power supply decreases by 50 A every 15 s until the output current drops to 0 A.

[0049] X-ray diffraction experiments were carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results in, it can be known that the alloy is composed of a BCC phase. Microstructure observation was carried out on the high-entropy alloy prepared in this example, as Figure 2 shown. The microstructure of Hf 20 (NbTiZr) 80 mainly shows a dendritic structure. According to the BSE imaging principle and the melting point differences between alloy elements, it can be inferred that the dendritic part is mainly the elements Hf and Nb with large atomic numbers and high melting points, and the interdendritic part is mainly the elements Ti and Zr with smaller atomic numbers and lower melting points. This conclusion can also be obtained from the Figure 3 EDS diagram of. Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as Figure 3 shown. It can be obtained that the tensile yield strength of this composition of refractory high-entropy alloy is 622.27 MPa, and the elongation after fracture is 5.36%. It can be seen that the strength and plasticity of the Hf20 alloy are slightly lower than those of the matrix Hf25 alloy. According to formula (1), the density of this alloy can be calculated to be 8.03 g / cm 3 .

[0050] Example 3

[0051] The chemical formula of a refractory high-entropy alloy with both improved performance and reduced cost is Hf 15 (NbTiZr) 85 , where Nb, Ti, and Zr are in equiatomic ratios. The specific steps of its preparation method are as follows:

[0052] (1) According to the chemical formula Hf 15 (NbTiZr) 85, the elemental metals were weighed according to the atomic ratio converted to the mass ratio, and the mass ratio of different elements was Hf: Nb: Ti: Zr = 34.73:34.15:17.60:33.53. The total weight was weighed as 120 g, and the mass of each element was accurate to two decimal places. Among them, the Hf content was 52.18 g, accounting for 28.94% of the total mass;

[0053] (2) The raw materials were placed in the crucible of a non-consumable vacuum melting furnace, and 50 g of pure Ti was placed in one crucible;

[0054] (3) After the vacuum in the furnace was pumped to 3×10 -3 Pa, argon was introduced to 50 Pa. Then the melting started. First, Ti was melted to exhaust the remaining oxygen in the furnace. The alloy ingot was melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, during the heating process, the output current of the power supply increased by 50 A every 15 s, increased to 550 A until the raw materials were completely melted, and maintained for 15 s. After cooling, the next melting was carried out; at the end of the last melting, during the cooling process, the output current of the power supply decreased by 50 A every 15 s until the output current decreased to 0 A.

[0055] X-ray diffraction experiments were carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results in, the alloy is composed of BCC phase. Microstructure observation was carried out on the high-entropy alloy prepared in this example, as Figure 2 shown. The microstructure of Hf 15 (NbTiZr) 85 mainly showed a dendritic structure. According to the BSE imaging principle and the melting point difference between alloy elements, it can be inferred that the dendritic part is mainly the elements Hf and Nb with large atomic numbers and high melting points, and the interdendritic part is mainly the elements Ti and Zr with smaller atomic numbers and lower melting points. This conclusion can also be obtained from the Figure 3 EDS diagram. Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as Figure 3 shown. It can be obtained that the tensile yield strength of this composition of refractory high-entropy alloy is 638.81 MPa, and the elongation after fracture is 10.96%. It can be seen that the strength and plasticity of the Hf15 alloy are slightly lower than those of the matrix Hf25 alloy. According to formula (1), the density of this alloy can be calculated as 7.67 g / cm 3 .

[0056] Example 4

[0057] A refractory high-entropy alloy with both improved performance and reduced cost has the chemical formula Hf 10 (NbTiZr) 90 , where Nb, Ti and Zr are in an equiatomic ratio. The specific preparation steps are as follows:

[0058] (1) According to the chemical formula Hf 10 (NbTiZr) 90 , convert the elemental metals into mass ratios according to the atomic ratios and weigh them. The mass ratios of different elements are Hf:Nb:Ti:Zr = 24.49:38.25:19.71:37.55. The total weight is weighed as 120 g, and the mass of each element is accurate to two decimal places. Among them, the content of Hf is 24.49 g, accounting for 20.41% of the total mass;

[0059] (2) Put the raw materials into the crucible of a non-consumable vacuum melting furnace, and put 50 g of pure Ti into one crucible;

[0060] (3) After pumping the vacuum in the furnace to 3×10 -3 Pa, introduce argon to 50 Pa. Then start melting. First, melt Ti to exhaust the remaining oxygen in the furnace. The alloy ingot is melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, during the heating process, the output current of the power supply increases by 50 A every 15 s, rising to 550 A until the raw materials are completely melted, and maintaining for 15 s. After cooling, the next melting is carried out; at the end of the last melting, during the cooling process, the output current of the power supply decreases by 50 A every 15 s until the output current drops to 0 A.

[0061] X-ray diffraction experiments were carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results in, it can be known that the alloy is composed of a BCC phase. Microstructure observation was carried out on the high-entropy alloy prepared in this example, as shown in Figure 2 . The microstructure of Hf 10 (NbTiZr) 90 mainly shows a dendritic structure. According to the BSE imaging principle and the melting point differences between alloy elements, it can be inferred that the dendritic part is mainly composed of elements Hf and Nb with large atomic numbers and high melting points, and the interdendritic part is mainly composed of elements Ti and Zr with smaller atomic numbers and lower melting points. This conclusion can also be obtained from the EDS diagram in Figure 3 . Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as shown in Figure 3 . It can be obtained that the tensile yield strength of this composition of refractory high-entropy alloy is 645.54 MPa, and the elongation after fracture is 12.63%. It can be seen that the strength and plasticity of the Hf10 alloy are slightly lower than those of the matrix Hf25 alloy but better than those of Hf15. According to formula (1), the density of this alloy can be calculated as 7.30 g / cm 3 .

[0062] Example 5

[0063] A refractory high-entropy alloy with both improved performance and reduced cost has the chemical formula Hf 5 (NbTiZr)95 , where Nb, Ti, and Zr are in equiatomic ratio. The specific preparation steps are as follows:

[0064] (1) According to the chemical formula Hf 5 (NbTiZr) 95 , convert to mass ratio according to the atomic ratio and weigh the elemental metals. The mass ratio of different elements is Hf:Nb:Ti:Zr = 13.00:42.85:22.08:42.07. Weigh a total of 120 g, and the mass of each element is accurate to two decimal places. Among them, the Hf content is 24.49 g, accounting for 10.83% of the total mass;

[0065] (2) Put the raw materials into the crucible of a non-consumable vacuum melting furnace, and put 50 g of pure Ti in one crucible;

[0066] (3) After pumping the vacuum in the furnace to 3×10 -3 Pa, introduce argon to 50 Pa. Then start melting. First, melt Ti to consume the remaining oxygen in the furnace. The alloy ingot is melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, during the heating process, the output current of the power supply increases by 50 A every 15 s, rising to 550 A until the raw materials are completely melted, and maintaining for 15 s. After cooling, carry out the next melting; at the end of the last melting, during the cooling process, the output current of the power supply decreases by 50 A every 15 s until the output current drops to 0 A.

[0067] X-ray diffraction experiments were carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results, the alloy is composed of BCC phase. Microstructure observation was carried out on the high-entropy alloy prepared in this example, as Figure 2 shown. The microstructure of Hf 5 (NbTiZr) 95 mainly shows a dendritic structure. According to the BSE imaging principle and the melting point difference between alloy elements, it can be inferred that the dendritic part is mainly the elements Hf and Nb with large atomic numbers and high melting points, and the interdendritic part is mainly the elements Ti and Zr with smaller atomic numbers and lower melting points. This conclusion can also be obtained from the Figure 3 EDS diagram. Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as Figure 3 shown. It can be obtained that the tensile yield strength of this composition of refractory high-entropy alloy is 692.88 MPa, and the elongation after fracture is 9.54%. It can be seen that the strength and plasticity of the Hf5 alloy are slightly higher than those of the matrix Hf25 alloy. According to formula (1), the density of this alloy can be calculated to be 6.92 g / cm 3 .

[0068] Example 6

[0069] The chemical formula of a refractory high-entropy alloy that combines performance improvement and cost reduction is Hf 0 (NbTiZr) 100 , where Nb, Ti, and Zr are in equiatomic ratio. The specific preparation steps are as follows:

[0070] (1) According to the chemical formula Hf 0 (NbTiZr) 100 , convert to mass ratio according to the atomic ratio and weigh the elemental metals. The mass ratio of different elements is Hf:Nb:Ti:Zr = 0:48.05:24.77:47.18. Weigh a total of 120 g, and the mass of each element is accurate to two decimal places. The content of Hf is 0 g;

[0071] (2) Put the raw materials into the crucible of a non-consumable vacuum melting furnace, and put 50 g of pure Ti in one crucible;

[0072] (3) After pumping the vacuum in the furnace to 3×10 -3 Pa, introduce argon to 50 Pa. Then start melting. First, melt Ti to exhaust the remaining oxygen in the furnace. The alloy ingot is melted repeatedly 6 times to obtain the refractory high-entropy alloy. During melting, during the heating process, the output current of the power supply increases by 50 A every 15 s, rising to 550 A until the raw materials are completely melted, and maintaining for 15 s. After cooling, carry out the next melting; at the end of the last melting, during the cooling process, the output current of the power supply decreases by 50 A every 15 s until the output current drops to 0 A.

[0073] An X-ray diffraction experiment was carried out on the high-entropy alloy prepared in this example. According to Figure 1 the results in, the alloy is composed of a BCC phase. The microstructure of the high-entropy alloy prepared in this example was observed, as Figure 2 shown. The microstructure of Hf 0 (NbTiZr) 100 mainly shows a dendritic structure. According to the BSE imaging principle and the melting point difference between alloy elements, it can be inferred that the dendritic part is mainly the element Nb with a large atomic number and a high melting point, and the interdendritic part is mainly the elements Ti and Zr with a smaller atomic number and a lower melting point. This conclusion can also be obtained from the Figure 3 EDS diagram of. Figure 4 Figure (a) shows the TEM image of the Hf 0 (NbTiZr) 100 refractory high-entropy alloy, (a) has a chemically ordered structure, and (a1)(a2) are the IFFT diagrams of (a); (b) shows the obstruction to dislocations; from Figure 4It can be seen that there is a nanoscale local chemical order structure in the alloy, which hinders the movement of dislocations, thus enabling the alloy to have high strength and plasticity. Tensile mechanical property tests were carried out on the refractory high-entropy alloy prepared in this example, as Figure 5 shown. It can be obtained that the tensile yield strength of this composition refractory high-entropy alloy is 721 MPa, and the elongation after fracture is 14%. It can be seen that the strength and plasticity of the Hf0 alloy are significantly higher than those of the matrix Hf25 alloy, and its strength is the best-performing group in the examples. According to formula (1), the density of the alloy can be calculated as 6.54 g / cm 3 , which is 22% lower than that of the Hf25 alloy.

Claims

1. A refractory high entropy alloy having both improved performance and reduced cost, characterized in that: The chemical formula of the refractory high entropy alloy is Hf a Nb b Ti c Zr d , in atomic percentage, 0≤a≤25.0%, 20.0%≤b≤35.0%, 20.0%≤c≤35.0%, 20.0%≤d≤35.0%, where a+b+c+d=100% and b=c=d.

2. A refractory high entropy alloy having both improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is Hf 25 (NbTiZr) 75 , wherein Nb, Ti and Zr are in equal atomic ratios.

3. A refractory high entropy alloy with improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is Hf 20 (NbTiZr) 80 , wherein Nb, Ti and Zr are in equal atomic ratios.

4. A refractory high entropy alloy with improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is Hf 15 (NbTiZr) 85 , wherein Nb, Ti and Zr are in equal atomic ratios.

5. A refractory high entropy alloy with improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is Hf 10 (NbTiZr) 90 , wherein Nb, Ti and Zr are in equal atomic ratios.

6. A refractory high entropy alloy with improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is Hf5(NbTiZr) 95 , wherein Nb, Ti and Zr are in equal atomic ratios.

7. A refractory high entropy alloy with improved performance and reduced cost according to claim 1, characterized in that: The chemical formula of the refractory high entropy alloy is NbTiZr, wherein Nb, Ti and Zr are in an equiatomic ratio.

8. A method for preparing a refractory high entropy alloy with improved performance and reduced cost as claimed in claim 1, characterized in that: Follow these steps:

1. According to the chemical formula Hf a Nb b Ti c Zr d , weigh the raw materials according to the atomic ratio; 2. Put the raw materials into the crucible of a non-consumable vacuum melting furnace, evacuate the furnace, introduce argon gas, and then perform vacuum arc melting, followed by furnace cooling to obtain an alloy ingot; 3. The alloy ingot is repeatedly melted and cooled to obtain the refractory high entropy alloy.

9. The method for preparing a refractory high entropy alloy with improved performance and reduced cost according to claim 8, characterized in that: In step 2, the vacuum in the furnace is evacuated to 3×10 -3 After reaching 50 Pa, argon gas was introduced.

10. The method for preparing a refractory high entropy alloy with improved performance and reduced cost according to claim 8, characterized in that: In step 3, the alloy ingot is repeatedly smelted 6 times.

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