Ti-Al-Nb-Zr-Ta-M refractory high-entropy alloy and preparation method thereof

Abstract

The invention discloses a Ti-Al-Nb-Zr-Ta-M refractory high-entropy alloy and a preparation method of the Ti-Al-Nb-Zr-Ta-M refractory high-entropy alloy. The expression of the alloy is (Ti Al Nb < c > Zr < d > Ta) < 100-x > M < x >, wherein a, b, c, d, e and x respectively represent the atomic percent of each component and meet the following conditions: a is 35-68, b is 10-20, c is 10-20, d is 12-25, e is 0.1-1, x is 0.1-3, and a + b + c + d + e + x = 100; and the atomic radius of the M element is smaller than that of the basic alloy components Ti, Al, Nb, Zr and Ta. And the alloy performance is optimal by regulating and controlling the content of the M element. The refractory high-entropy alloy has a series of advantages of ultrahigh room-temperature tensile strength and specific strength, good percentage elongation after fracture, relatively good high-temperature mechanical properties and the like, the preparation process is simple, and the production cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of new metal materials, and relates to a Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy and a preparation method thereof, and specifically relates to a high specific strength and high elongation (Ti a Al b Nb c Zr d Ta e ) 100-x M x Refractory high entropy alloy and preparation method thereof. Background Art

[0002] High-entropy alloys (HEAs) are an emerging material that has garnered significant attention in recent years. They defy the traditional design principle of alloys consisting primarily of one or two primary elements. HEAs are composed of multiple primary elements, offering a vast compositional space for the development of new alloys. Due to the high-entropy effect, HEAs often form as single-phase solid solutions, primarily in face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP) structures. BCC alloys, often composed of refractory elements, are also known as refractory HCAs. Refractory HCAs exhibit high room-temperature strength and excellent high-temperature performance.

[0003] However, the main problem limiting the application of refractory high entropy alloys is their poor room temperature plasticity, making it difficult to achieve a balance between room temperature strength and plasticity. The currently developed TiZrHfNbTa alloys and their derivative systems are among the few alloy systems that achieve both high strength and high plasticity. However, the TiZrNbHfTa alloy system has a high density, generally around 9.9 g / cm 3 At the same time, due to the high content of Hf and Ta, the production cost is high, and this type of alloy is not suitable for industrial production.

[0004] A search of existing patent literature revealed that Chinese patent application CN112899544A - A nano-scale B2 phase precipitation strengthened TixZrNbAly multi-principal alloy and its preparation method - developed a series of alloys with excellent performance, but the maximum yield strength is between 790 and 1050 MPa, which is difficult to meet the occasions with high performance requirements and has weak market competitiveness.

[0005] The cast refractory high-entropy alloys currently developed maintain a certain elongation at break during tensile tests while their yield strength rarely exceeds 1200 MPa. The few ductile alloys that exceed 1200 MPa need to be obtained through tedious heat treatment and deformation, which increases the alloy production cost sharply and is not conducive to industrial promotion.

[0006] Chinese patent application CN 113881886 A - A high-specific-strength Ti-Al-Nb-Zr-Ta refractory high-entropy alloy - has designed and developed a series of cast alloys with excellent performance. However, the tensile strength of these alloys is less than 1200 MPa, which makes it difficult to meet the requirements of more extreme services, limiting the promotion and application of such materials. Summary of the Invention

[0007] The purpose of the present invention is to provide a Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy and a preparation method thereof, which is a high strength and high specific strength (Ti a Al b Nb c Zr d Ta e ) 100-x M x Refractory high-entropy alloys address the challenges of traditional refractory high-entropy alloys, such as poor room-temperature elongation, high density, and high production costs. These alloys offer low density, high strength, high room-temperature elongation, and excellent high-temperature performance. Furthermore, they offer low production costs and simple processing, giving them enormous potential for application in engineering.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy, the alloy expression of which is (Ti a Al b Nb c Zr d Ta e ) 100-x M x , where a, b, c, d, e, and x represent the atomic percentages of the corresponding components, respectively, and satisfy the following conditions: a is 35-68, b is 10-20, c is 10-20, d is 12-25, e is 0.1-1, x is 0.1-3, and a+b+c+d+e+x=100; the atomic radius of the M element is smaller than the atomic radius of all the components of the base alloy, Ti, Al, Nb, Zr, and Ta. This refractory high-entropy alloy combines high specific strength with good elongation after fracture, and is a lightweight refractory high-entropy alloy. The room temperature tensile strength is 1150-1340 MPa, the room temperature tensile elongation after fracture is 10-17.1%, and the specific strength is 220-260 MPa·g. -1 cm 3 .

[0010] As an embodiment of the present invention, M is one or more transition elements V, Cr, Fe, Co, Ni and Cu. The characteristics of M element are: chemical properties are similar to Ti a Alb Nb c Zr d Ta e The basic alloy components Ti, Al, Nb and Zr are similar, and their atomic radius is smaller than the atomic radius of each basic alloy component. Solid solution strengthening is the most important strengthening method for refractory high entropy alloys. The lattice distortion caused by the difference in atomic radius will cause internal stress field, and the movement of dislocations therefore requires additional work, thereby causing an increase in yield strength and tensile strength. a Al b Nb c Zr d Ta e Adding a small amount of transition element M with a small atomic radius to the alloy can intensify the lattice distortion while ensuring that no new phase appears, thereby producing a strong solid solution strengthening effect.

[0011] In some embodiments, the atomic number ratio of each component is 55.5 for Ti, 13 for Al, 14 for Nb, 15 for Zr, 0.5 for Ta, and 2 for V.

[0012] In some embodiments, the atomic number ratio of each component is 56.5 for Ti, 13 for Al, 14 for Nb, 15 for Zr, 0.5 for Ta, and 1 for Cr.

[0013] In some embodiments, the atomic ratio of each component is 62.5 for Ti, 12 for Al, 12 for Nb, 12 for Zr, 0.5 for Ta, and 1 for Fe.

[0014] In some embodiments, the atomic ratio of each component is 53.5 for Ti, 10 for Al, 15 for Nb, 20 for Zr, 0.5 for Ta, and 1 for Ni.

[0015] In some embodiments, the atomic ratio of each component is 55.5 for Ti, 13 for Al, 14 for Nb, 15 for Zr, 0.5 for Ta, 1 for V, 0.5 for Cr, and 0.5 for Fe.

[0016] The present invention also provides a method for preparing the above-mentioned Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy, the method comprising the following steps:

[0017] S1. Ingredients: Ingredients are prepared according to the alloy expression;

[0018] S2. Melting and suction casting: Place the raw materials in order of melting point, with Al and M at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. Vacuum and fill with protective gas for melting, and finally suction casting.

[0019] In one embodiment of the present invention, the raw materials have a titanium purity greater than 99.5wt%, an aluminum purity greater than 99.9wt%, a niobium purity greater than 99.9wt%, a zirconium purity greater than 99.9wt%, a tantalum purity greater than 99.9wt%, and a M purity greater than 99.9wt%. The raw materials are weighed using an electronic balance with an accuracy of 0.001g to accurately measure the mass of each component within a tolerance of ±0.005g.

[0020] As an embodiment of the present invention, the raw materials are polished, cleaned and dried.

[0021] As an embodiment of the present invention, the polishing is to remove the oxide film on the surface of the raw material by polishing with a wire brush or a grinding wheel machine.

[0022] As an embodiment of the present invention, the cleaning is ultrasonic cleaning in anhydrous ethanol, and the cleaning time is 100s to 200s.

[0023] In one embodiment of the present invention, the smelting is conducted by striking an arc. Specifically, striking an arc is conducted in a non-consumable vacuum arc furnace. In principle, the raw materials are placed in order of melting point into a water-cooled copper crucible in the non-consumable vacuum arc furnace. However, due to the relatively small amount of element M added, it is placed at the bottom. Due to the high arc temperature, placing the raw materials in this order ensures the melting of high-melting-point alloying elements and prevents the evaporation or volatilization of low-melting-point elements. Smelting is repeated five to seven times to ensure a uniform alloy composition.

[0024] As an embodiment of the present invention, a pure Ti ingot is additionally placed in one of the water-cooled copper crucibles in the water-cooled copper tray of the non-consumable vacuum arc furnace.

[0025] As an embodiment of the present invention, before the arc melting of the alloy, the preset extra Ti ingot is melted first to consume the free oxygen in the furnace, and then the melting of the alloy sample is started. Since titanium is very active at high temperatures, the elemental titanium is first used as the melting target to further consume the free oxygen in the furnace. The specific steps of the present invention are vacuuming, filling with argon, melting the Ti ingot, and melting the prepared alloy. After each subsequent melting, the Ti ingot is melted for 1 minute after the arc is started, and then the target alloy is melted. A pit is reserved on the furnace plate of the electric arc furnace for placing the Ti ingot. The Ti ingot does not need to be turned over. Except for the first time, the alloy ingot needs to be turned over each time thereafter to ensure uniform composition. In order to ensure high vacuum, the furnace will not be opened during the melting process, and the furnace will not be opened to take out the ingot until the melting is completed. The Ti ingot is generally not taken out unless the Ti ingot is severely oxidized and a new Ti ingot is replaced and put in.

[0026] As an embodiment of the present invention, the melting current is 250A to 500A, the arc starting current is 250A to 300A, and the current is increased to above 400A after melting.

[0027] In one embodiment of the present invention, during the melting process in step A2, each alloy ingot is melted for at least one minute, then flipped after cooling, and this process is repeated four to seven times. Multiple elements of the sample are placed in the same well on the furnace plate. During the first melting process, they are melted to form a single alloy ingot. Repeated flipping and melting ensures uniform alloy composition.

[0028] As an embodiment of the present invention, the vacuum degree of the vacuum pumping reaches 5×10 3 Pa or above.

[0029] As an embodiment of the present invention, the protective gas is argon. Ti, Al, Nb, Zr, Ta and M in this alloy system are very easy to oxidize during high temperature melting, so a high vacuum degree and the addition of inert gas protection are required.

[0030] The present invention discovered that for a body-centered cubic single-phase solid solution, the improvement in alloy yield strength and tensile strength primarily comes from solid solution strengthening. Atomic size differences are the primary factor determining the effect of solid solution strengthening. The present invention further enhances strength by adding alloying elements with atomic radii smaller than those of the base alloying components. Cost is also a consideration in the selection of alloying elements to enhance the commercial competitiveness of the alloy and accelerate its industrialization.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention strengthens Ti by adding a small amount of element M to solid solution a Al b Nb c Zr d Ta e Alloy, so that its strength and specific strength are further improved, and the alloy has good elongation after fracture;

[0033] (2) Ti of the present invention a Al b Nb c Zr d Ta e Nb, the smallest element in the alloy, has an atomic radius of 142.9 pm, while V, the largest element in the M element, has an atomic radius of 131.6 pm. The atomic radii of the other elements, Cr, Fe, Co, Ni, and Cu, are all around 125 pm. The atomic radii of the M elements are much smaller than those of the basic alloy components, and adding a small amount can achieve a good solid solution strengthening effect.

[0034] (3) The present invention can obtain a density of 5.1 to 5.29 g / cm 3 The low-density refractory high-entropy alloy is higher than the TiAlNbV system with the lowest density of existing refractory high-entropy alloys (5.59g / cm 3) is lower, the maximum yield strength is 1150~1340MPa, and the specific strength is 220~260MPa·g -1 cm 3 , the performance has been greatly improved, especially the strength and specific strength are much higher than those of the alloys reported so far;

[0035] (4) The properties of the refractory high entropy alloy of the present invention can be easily optimized by adjusting the content of the M element;

[0036] (5) The present invention contains elements with low prices, low cost, and the alloy has excellent comprehensive mechanical properties. Moreover, it is obtained under cast conditions and has huge market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0038] Figure 1 XRD patterns of Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy blocks in Examples 1, 2, 3 and Comparative Example 1;

[0039] Figure 2 EBSD diagram of the as-cast Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy in Example 1;

[0040] Figure 3 The stress-strain curves of the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloys in Examples 1, 2, 3, 5 and Comparative Example 1 under room temperature tensile tests are shown;

[0041] Figure 4 These are the tensile fracture morphologies of Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy at room temperature; among them, (a) Example 1, (b) Comparative Example 3. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented under the premise of the technical solution of the present invention, provide detailed implementation methods and specific operating procedures, and will help those skilled in the art to further understand the present invention. It should be pointed out that the scope of protection of the present invention is not limited to the following embodiments, and several adjustments and improvements made under the premise of the concept of the present invention all fall within the scope of protection of the present invention.

[0043] The raw materials used in the examples of this application can be obtained from commercial channels.

[0044] Example 1

[0045] A (Ti a Al b Nbc Zr d Ta e ) 100-x M x Refractory high entropy alloy, its alloy expression is Ti 55.5 Al 13 Nb 14 Zr 15 Ta 0.5 V2, whose theoretical density is 5.171 g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0046] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, tantalum with a purity of 99.9 wt%, and vanadium with a purity of 99.9 wt% were selected and prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first removed by grinding with a wire brush or a grinder. The raw materials were then ultrasonically cleaned in a beaker of anhydrous ethanol for 200 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0047] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al and V at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump in turn to evacuate the vacuum to a degree of 5×10 3 After the pressure reaches Pa, argon gas is filled for protection. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current is between 250A and 500A. Each alloy ingot is melted for at least one minute. After cooling, turn the ingot upside down and repeat the previous step six times to ensure thorough and uniform melting of the alloy. After melting, the alloy is suction-cast into a copper mold.

[0048] (3) Ti obtained in this embodiment 55.5 Al 13 Nb 14 Zr 15 Ta 0.5 The XRD pattern of V2 alloy is as follows Figure 1 The results show that the as-cast alloy consists of a single BCC phase. 55.5 Al 13 Nb 14 Zr 15 Ta 0.5 EBSD images of V2 alloy are shown in Figure 2. Figure 2The tensile test results are shown in Figure 3 As shown in Table 1, the performance data of the alloy is 1341MPa, the elongation after fracture is 12.4%, and the specific strength is 259.3MPa·g -1 cm 3 The fracture morphology of the alloy is as follows Figure 4 As shown in the figure, there are a lot of dimples on the fracture surface, indicating that the fracture is ductile fracture.

[0049] Example 2

[0050] A (Ti a Al b Nb c Zr d Ta e ) 100-x M x High entropy alloy, its alloy expression is Ti 56.5 Al 13 Nb 14 Zr 15 Ta 0.5 Cr1, its theoretical density is 5.166g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0051] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, tantalum with a purity of 99.9 wt%, and chromium with a purity of 99.9 wt% were selected and prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first removed by grinding with a wire brush or a grinder. The raw materials were then ultrasonically cleaned in a beaker of anhydrous ethanol for 100 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0052] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al and Cr at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump to evacuate the vacuum to a degree of 5×10 3 Argon gas is used for shielding when the pressure exceeds Pa. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current ranges from 250A to 450A. Each alloy ingot is melted for at least one minute, then flipped after cooling. This process is repeated five times to ensure thorough and uniform melting. After melting is complete, the alloy is suction-cast into a copper mold.

[0053] (3) The XRD pattern of the alloy is as follows Figure 1 The stress-strain curve of tensile stress at room temperature is shown in Figure 3 As shown in Table 1, the performance data of the alloy is 1234MPa, the elongation after fracture is 12.5%, and the specific strength is 238.9MPa·g -1 cm 3 .

[0054] Example 3

[0055] A (Ti a Al b Nb c Zr d Ta e ) 100-x M x High entropy alloy, its alloy expression is Ti 62.5 Al 12 Nb 12 Zr 12 Ta 0.5 Fe1, whose theoretical density is 5.173 g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0056] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, tantalum with a purity of 99.9 wt%, and iron with a purity of 99.9 wt% were selected and prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first removed by grinding with a wire brush or a grinder. The raw materials were then ultrasonically cleaned in a beaker of anhydrous ethanol for 100 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0057] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al and Fe at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump in turn to evacuate the vacuum to a degree of 5×10 3 After the temperature reaches Pa, argon shielding is applied. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current ranges from 250A to 450A. Each alloy ingot is melted for at least one minute, then flipped after cooling. This process is repeated five times to ensure thorough and uniform melting. After melting is complete, the alloy is suction-cast into a copper mold.

[0058] (3) The XRD pattern of the alloy is as follows Figure 1 The room temperature tensile test results are shown in Figure 3 As shown in Table 1, the performance data of the alloy is 1270MPa, the elongation after fracture is 13.3%, and the specific strength is 245.5MPa·g -1 cm 3 .

[0059] Example 4

[0060] A (Ti a Al b Nb c Zr d Ta e ) 100-x M x High entropy alloy, its alloy expression is Ti 53.5 Al 10 Nb 15 Zr 20 Ta 0.5 Ni1, whose theoretical density is 5.183 g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0061] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, tantalum with a purity of 99.9 wt%, and nickel with a purity of 99.9 wt% were selected and prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first removed by grinding with a wire brush or a grinder. The raw materials were then ultrasonically cleaned in a beaker of anhydrous ethanol for 100 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0062] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al and Ni at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump in turn to evacuate the vacuum to a degree of 5×10 3 After the temperature reaches Pa, argon shielding is applied. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current ranges from 250A to 450A. Each alloy ingot is melted for at least one minute, then flipped after cooling. This process is repeated five times to ensure thorough and uniform melting. After melting is complete, the alloy is suction-cast into a copper mold.

[0063] (3) The performance data of the alloy composition are shown in Table 1. The tensile strength is 1290 MPa, the elongation after fracture is 12.3%, and the specific strength is 248.9 MPa·g -1 cm 3 .

[0064] Example 5

[0065] A (Ti a Al b Nb c Zr d Ta e ) 100-x M x High entropy alloy, its alloy expression is Ti 55.5 Al 13 Nb 14 Zr 15 Ta 0. 5V1Cr 0.5 Fe 0.5 , its theoretical density is 5.186g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0066] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, tantalum with a purity of 99.9 wt%, vanadium with a purity of 99.9%, chromium with a purity of 99.9% and iron with a purity of 99.9 wt% were selected and the ingredients were prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first polished off with a wire brush or a grinding wheel. The raw materials were then ultrasonically cleaned in a beaker containing anhydrous ethanol for 100 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0067] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al, V, Cr and Fe at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump in turn to evacuate the vacuum to a degree of 5×10 3 After the temperature reaches Pa, argon shielding is applied. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current ranges from 250A to 450A. Each alloy ingot is melted for at least one minute, then flipped after cooling. This process is repeated five times to ensure thorough and uniform melting. After melting is complete, the alloy is suction-cast into a copper mold.

[0068] (3) The room temperature tensile test results of the alloy are as follows Figure 3 As shown in Table 1, the performance data is as follows: the tensile strength is 1213 MPa, the elongation after fracture is 17.1%, and the specific strength is 233.9 MPa·g -1 cm 3 .

[0069] Comparative Example 1

[0070] A Ti without M element 57.5 Al 13 Nb 14 Zr 15 Ta 0.5 High entropy alloy, its theoretical density is 5.139g / cm 3 , as a more detailed example, its preparation method and related testing include the following steps:

[0071] (1) Ingredients: Titanium with a purity of 99.5 wt%, aluminum with a purity of 99.9 wt%, niobium with a purity of 99.9 wt%, zirconium with a purity of 99.9 wt%, and tantalum with a purity of 99.9 wt% were selected and prepared according to the alloy formula. Before weighing the raw materials, the oxide film on the surface of the raw materials was first removed by grinding with a wire brush or a grinder. The raw materials were then ultrasonically cleaned in a beaker of anhydrous ethanol for 100 s and then completely dried with a hair dryer. The mass of each component was accurately weighed using an electronic balance with an accuracy of 0.001 g (the error requirement was within ±0.005 g).

[0072] (2) Melting and suction casting: In a non-consumable vacuum arc furnace, place the metal raw materials in the order of melting point into a water-cooled copper crucible, with Al at the bottom, Ti and Zr in the middle, and Nb and Ta at the top. After the raw materials are placed, turn on the mechanical pump and diffusion pump to evacuate the vacuum to a degree of 5×10 3 Argon gas is used for shielding when the pressure exceeds Pa. The arc is struck and melting begins. Before melting the alloy, a Ti ingot pre-placed in the furnace is melted to further deplete the free oxygen in the furnace. For each alloy melt, the arc starting current is 250A, and the melting current ranges from 250A to 450A. Each alloy ingot is melted for at least one minute, then flipped after cooling. This process is repeated five times to ensure thorough and uniform melting. After melting is complete, the alloy is suction-cast into a copper mold.

[0073] (3) The XRD pattern of the alloy is as follows Figure 1 The results show that the alloy is composed of a single BCC phase. The room temperature tensile test results are shown in Figure 3 As shown in Table 1, the alloy performance data is as follows: the tensile strength is 1075MPa, the elongation after fracture is 11.2%, and the specific strength is 209.2MPa·g -1 cm 3 .

[0074] Comparative Example 2

[0075] A Ti 57.45 Al 13 Nb 14 Zr 15 Ta 0.5 V 0.05 The refractory high entropy alloy was prepared in the same manner as in Example 1. It was arc-melted five times and suction-cast into a copper mold. Wire cutting was then used to prepare tensile specimens. Tensile tests were performed, and the performance data were found to be as shown in Table 1. 57.45 Al 13 Nb 14 Zr 15 Ta 0.5 V 0.05 The tensile strength and elongation after fracture of the refractory high entropy alloy are 1136 MPa and 13.1% respectively. Combined with Example 1, the room temperature tensile test results show that the V content is too low to achieve a good solid solution strengthening effect.

[0076] Comparative Example 3

[0077] A Ti 53.5 Al 14 Nb 14 Zr 15 Ta 0.5 The V4 refractory high entropy alloy was prepared in the same manner as in Example 1. It was arc-melted five times and suction-cast into a copper mold. Tensile specimens were then prepared by wire cutting and subjected to tensile testing. Finally, it was found that Ti 53.5 Al 14 Nb 14 Zr 15 Ta 0.5 The performance data of V4 alloy are shown in Table 1. The tensile strength and elongation after fracture are 654MPa and 0.3% respectively. The alloy has almost no elongation after fracture. Combined with Example 1, it is shown that excessive V is not conducive to the solid solution strengthening of the alloy and leads to brittle fracture due to lattice instability. Figure 4 , which is a typical rock candy-like brittle fracture morphology.

[0078] Comparative Example 4

[0079] A Ti 63.45 Al 12 Nb 12 Zr 12 Ta 0.5 Fe 0.05 The refractory high entropy alloy was prepared in the same manner as in Example 3. It was arc-melted five times and suction-cast into a copper mold. A tensile specimen was then prepared by wire cutting and subjected to tensile testing. The performance data are shown in Table 1. The tensile strength and elongation after fracture were 1121 MPa and 14.1%, respectively. In conjunction with Example 3, illustrate If the Fe content is too low, the solid solution strengthening will not be obvious.

[0080] Comparative Example 5

[0081] A Ti 59.5 Al 12 Nb 12 Zr 12 Ta 0.5 An Fe4 refractory high-entropy alloy was prepared using the same method as in Example 3. It was arc-melted five times and suction-cast into a copper mold. Tensile specimens were then prepared using wire cutting and subjected to tensile testing. The tensile strength and elongation were 1090 MPa and 7.6%, respectively, as shown in Table 1. In contrast to Example 3, excessive Fe content negates the solid solution strengthening effect, resulting in reduced strength and elongation.

[0082] Comparative Example 6

[0083] A Ti 53.5 Al 13 Nb 14 Zr 15 Ta 0.5 A Cr4 refractory high-entropy alloy was prepared using the same method as in Example 3. Arc melting was performed five times and suction casting was performed into a copper mold. Tensile specimens were then prepared using wire cutting and subjected to tensile testing. The tensile strength and elongation were 892 MPa and 8.7%, respectively, as shown in Table 1. In contrast to Example 3, excessive Cr content negated the solid solution strengthening effect, resulting in reduced strength and elongation.

[0084] Table 1 Tensile performance data of examples and comparative examples

[0085]

[0086]

[0087] In summary, the present invention (Ti a Al b Nb c Zr d Ta e ) 100-x M x Refractory high-entropy alloys can be used to prepare high-performance engineering structural materials, with promising applications in aerospace, aviation, and the automotive sector. By adding an appropriate amount of the element M, the alloy's properties can be optimized. Due to solid solution strengthening, the alloys exhibit high strength and a reasonable room-temperature elongation. The alloy preparation process is simple, making it suitable for industrial production.

[0088] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy, characterized in that: Its alloy expression is (Ti a Al b Nb c Zr d Ta e ) 100-x M x , where a, b, c, d, e and x represent the atomic percentages of the corresponding components, respectively, and satisfy the following conditions: a is 35-68, b is 10-20, c is 10-20, d is 12-25, e is 0.1-1, x is 0.1-3, a+b+c+d+e+x=100; the atomic radius of element M is smaller than those of Ti, Al, Nb, Zr and Ta.

2. The Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 1, characterized in that The atomic radius of the M element is smaller than that of the base alloy Ti a Al b Nb c Zr d Ta e The atomic radii of all components of the alloy.

3. The Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 1, characterized in that M is one or more of V, Cr, Fe, Co, Ni and Cu.

4. A method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 1, characterized in that: The method comprises the following steps: S1. Ingredients: Ingredients are prepared according to the alloy expression; S2. Melting and suction casting: Place Al and M in the raw materials at the bottom, Ti and Zr in the middle, Nb and Ta at the top, evacuate and fill with protective gas for melting, and finally suction cast.

5. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 4, characterized in that: The purity of titanium in the raw materials is greater than 99.5wt%, the purity of aluminum is greater than 99.99wt%, the purity of niobium is greater than 99.9wt%, the purity of zirconium is greater than 99.9wt%, the purity of tantalum is greater than 99.9wt%, and the purity of M is greater than 99.9wt%.

6. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 4, characterized in that: The smelting is arc smelting; before the arc smelting of the alloy, a preset extra Ti ingot is melted first to consume the free oxygen in the furnace, and then the smelting of the target alloy sample is started.

7. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 4, characterized in that: The melting current is 250A-500A.

8. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 7, characterized in that: The arc starting current is 250A~300A, and the current is increased to 400A-500A after melting.

9. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 4, characterized in that: During smelting, each alloy ingot is melted for at least one minute, and then turned over after the alloy cools down, and repeated 4 to 7 times.

10. The method for preparing the Ti-Al-Nb-Zr-Ta-M refractory high entropy alloy according to claim 4, characterized in that: The vacuum degree of vacuum pumping reaches 5×10 3 Pa or above; the protective gas is argon.

Images