A TiZrMo-based refractory high-entropy alloy and its preparation method

Abstract

This invention belongs to the field of metallic materials technology, specifically a TiZrMo-based refractory high-entropy alloy and its preparation method. The refractory high-entropy alloy is composed of any two of Al, Cr, and Nb, and Ti, Zr, and Mo. The atomic radius difference δ of the refractory high-entropy alloy is ≤6.6%, the alloy entropy enthalpy ratio Ω is ≥1.1, and the mixing enthalpy ΔH is... mix The energy density ranges from -18.0 to 4.0 kJ / mol, and the vacancy electron concentration (VEC) is <6.87. Furthermore, the preparation method of this invention has the advantages of simple steps, easily controllable composition, high production efficiency, and near-net-shape forming. The prepared refractory high-entropy alloy has a stable microstructure and a density of less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ at 800℃ for 12 hours. 2 It is low in cost and easy to apply on a large scale in industrial applications.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to a TiZrMo-based refractory high-entropy alloy and its preparation method. Background Technology

[0002] The rapid development of high-temperature fields such as modern aerospace, nuclear reactors, weaponry, and gas turbines has led to increasingly stringent requirements for the performance of high-temperature structural materials. However, the performance of traditional alloys, represented by nickel-based alloys, has reached its limit, necessitating disruptive new alloy design concepts. Refractory high-entropy alloys break away from the traditional concept of alloys being dominated by one or two alloying elements, combining multiple high-melting-point elements to achieve better high-temperature strength, resistance to high-temperature softening, corrosion resistance, and radiation resistance. This represents a new direction and approach for developing new high-temperature, high-strength structural materials. However, current research is still in its early stages. Alloy composition design needs further refinement, and most alloys exhibit limited properties, including room-temperature brittleness, high alloy density, and low high-temperature oxidation resistance. Furthermore, composition design is currently challenging: refractory high-entropy alloys are composed of multiple elements, requiring consideration of the proportions of these elements, their atomic radii, and interactions. The design and optimization of novel refractory high-entropy alloys require extensive experimental and theoretical calculations.

[0003] Currently, most (>90%) methods for preparing refractory high-entropy alloys in China employ melting. However, the complexity of the composition and the significant melting point differences between different components lead to substantial volatilization and loss of low-melting-point elements in refractory high-entropy alloys prepared by melting, easily resulting in significant elemental segregation and introducing defects such as porosity and looseness into the alloy. Furthermore, the batching and machining processes for alloys prepared by melting are cumbersome, resulting in irregular shapes and limited dimensions. Powder metallurgy, as an advanced and mature forming method, features near-net-shape forming, almost no component segregation, fine and uniform grains without anisotropy, and the ability to produce large quantities with minimal subsequent machining. It has significant advantages in preparing homogenized elements and forming large-size, irregularly shaped components. The challenges of preparing refractory high-entropy alloys by powder metallurgy include the difficulty in controlling powder preparation and the crucial importance of a uniform, fine powder composition. When using processes such as ball milling, prolonged mechanical activation treatment is necessary to ensure system mixing. However, mechanical stirring and milling processes can lead to powder surface oxidation or contamination, affecting the oxidation resistance and mechanical properties of high-entropy alloys. Furthermore, the powder raw materials require high-quality raw materials and are expensive. Controlling the alloying process is challenging, and high-entropy alloys are typically prepared using high-temperature sintering under oxygen-free conditions or spark plasma sintering. However, in these methods, the sintering conditions significantly influence the composition, microstructure, and properties of the high-entropy alloy. Excessively high or low temperatures, inappropriate holding times, and inadequate atmosphere control can all lead to weight loss, thus reducing its performance. Summary of the Invention

[0004] To address the problems existing in the prior art, the main objective of this invention is to propose a TiZrMo-based refractory high-entropy alloy and its preparation method.

[0005] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0006] A TiZrMo refractory high-entropy alloy, by atomic percentage, is composed of any two of the following: 5-35% Al, 5-35% Cr, and 5-35% Nb, and 5-35% Ti, 5-35% Zr, and 5-35% Mo; the atomic radius difference δ ≤ 6.6%, the alloy entropy enthalpy ratio Ω ≥ 1.1, and the mixing enthalpy ΔH mix The range is -18.0 to 4.0 kJ / mol, and the vacancy electron concentration VEC < 6.87.

[0007] As a preferred embodiment of the TiZrMo-based refractory high-entropy alloy described in this invention, the density of the refractory high-entropy alloy is less than 7.00 g / cm³. 3It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ at 800℃ for 12 hours. 2 .

[0008] To solve the above-mentioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0009] A method for preparing the above-mentioned TiZrMo refractory high-entropy alloy includes the following steps:

[0010] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0011] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0012] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0013] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0014] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S1, the purity of the elemental powder is ≥99.5% and the particle size is <45μm.

[0015] In a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S1, the mixer is a three-dimensional mixer, and mixing is carried out under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 1 to 5 hours.

[0016] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S2, the wet milling solvent is anhydrous ethanol and / or n-heptane and / or acetone, and the solid-liquid ratio of the preliminary mixture and the wet milling solvent is 100g:(20~100)mL.

[0017] In a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S2, the grinding balls are stainless steel balls of different sizes, with diameters of 20 mm, 10 mm and 6 mm respectively, and their mass ratio is (0.5~10):(0.5~10):1.

[0018] In a preferred embodiment of the preparation method of the TiZrMo-based refractory high-entropy alloy of the present invention, in step S2, the high-energy ball milling adopts an omnidirectional planetary ball mill, the ball-to-material ratio is 5-20:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 200-400 r / min, the rotation speed of the ball mill jar is 200-400 r / min, the rotation speed of the large disc is 0.5-2 r / min, and the ball milling time is 30-100 h.

[0019] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S2, the ball milling jar is taken out every 5 hours during high-energy ball milling, and the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar under the protection of inert gas, so that the powder is fully alloyed.

[0020] In a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S3, the drying process is carried out under vacuum in a drying oven with a vacuum degree ≤1×10⁻⁶. -3 Pa, drying time is 5-10 hours.

[0021] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S3, the pressing is carried out by steel mold pressing; the pressing pressure is 100-350MPa, the holding time is 30-120s; and the sieving is carried out by a 325-400 mesh sieve.

[0022] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S4, the vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and the vacuum is evacuated to a vacuum degree ≤1×10⁻⁶. -3 Pa; heat to the sintering temperature at a heating rate of 3-10℃ / min and hold for 180-420 min.

[0023] In a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S4, during vacuuming, a vacuum is first drawn, then argon protective gas is introduced for furnace cleaning, and then a vacuum is drawn again. This process is repeated at least 5 times until the vacuum degree is ≤1×10⁻⁶. -3 Pa.

[0024] As a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S4, the sintering temperature is 66-83% of the melting point of the refractory high-entropy alloy.

[0025] In a preferred embodiment of the preparation method of the TiZrMo refractory high-entropy alloy of the present invention, in step S4, the cooling is furnace cooling.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention proposes a TiZrMo-based refractory high-entropy alloy and its preparation method. The refractory high-entropy alloy is composed of any two of Al, Cr, and Nb, and Ti, Zr, and Mo. The atomic radius difference δ of the refractory high-entropy alloy is ≤6.6%, the alloy entropy enthalpy ratio Ω is ≥1.1, and the mixing enthalpy ΔH is... mix The energy density ranges from -18.0 to 4.0 kJ / mol, and the vacancy electron concentration (VEC) is <6.87. Furthermore, the preparation method of this invention has the advantages of simple steps, easily controllable composition, high production efficiency, and near-net-shape forming. The prepared refractory high-entropy alloy has a stable microstructure and a density of less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ at 800℃ for 12 hours. 2 It is low in cost and easy to apply on a large scale in industrial applications. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0029] Figure 1 The image shows the XRD pattern of the refractory high-entropy alloy prepared in Example 1 of this invention.

[0030] Figure 2 The image shows the XRD pattern of the refractory high-entropy alloy prepared in Example 2 of this invention.

[0031] Figure 3 The image shows the XRD pattern of the refractory high-entropy alloy prepared in Example 3 of this invention.

[0032] Figure 4 The image shows the XRD pattern of the refractory high-entropy alloy prepared in Comparative Example 1 of this invention.

[0033] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] To address the problems of existing technologies, this invention innovatively combines lightweight elements with similar atomic sizes and relatively oxidation-resistant properties (Al, Ti, Cr, Zr) with high-temperature resistant elements (Mo, Nb) to create a refractory high-entropy alloy. This is based on multiple parameters, including valence electron concentration, theoretical melting point of the alloy, alloy mixing entropy, alloy mixing enthalpy, and atomic size difference, as criteria for refractory high-entropy alloys. The result is a alloy that simultaneously satisfies structural stability and has a density less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ after 12 hours at 800℃. 2 A novel high-performance refractory high-entropy alloy with specific properties and its preparation method.

[0036] According to one aspect of the present invention, the present invention provides the following technical solution:

[0037] A TiZrMo refractory high-entropy alloy, by atomic percentage, is composed of any two of the following: 5-35% Al, 5-35% Cr, and 5-35% Nb, and 5-35% Ti, 5-35% Zr, and 5-35% Mo; the refractory high-entropy alloy has an entropy enthalpy ratio Ω ≥ 1.1, an atomic radius difference δ ≤ 6.6%, and a mixing enthalpy ΔH. mix The range is -18.0 to 4.0 kJ / mol, and the vacancy electron concentration VEC < 6.87.

[0038] in,

[0039]

[0040]

[0041]

[0042]

[0043] VEC=∑C i (VEC i )

[0044] In the above formula, T m ΔS represents the melting point of a refractory high-entropy alloy. mix For the mixed entropy change of the refractory high-entropy alloy system, ΔH mixFor the mixing enthalpy change of refractory high-entropy alloy systems, (T m ) i Let r be the melting point of the i-th element. i Let be the atomic radius of the i-th element. Let C be the enthalpy of mixing between the i-th and j-th elements. i and C j The atomic percentage content of the i-th and j-th elements, respectively, VEC i Let be the vacancy electron concentration of the i-th element.

[0045] Preferably, the density of the refractory high-entropy alloy is less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ at 800℃ for 12 hours. 2 .

[0046] According to another aspect of the present invention, the present invention provides the following technical solution:

[0047] A method for preparing the above-mentioned TiZrMo refractory high-entropy alloy includes the following steps:

[0048] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0049] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0050] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0051] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0052] Preferably, in step S1, the purity of the elemental powder is ≥99.9%, and the particle size is <45μm; the mixer is a three-dimensional mixer, and mixing is carried out under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 1 to 5 hours.

[0053] Preferably, in step S2, the wet grinding solvent is anhydrous ethanol and / or n-heptane and / or acetone, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:(20-100)mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of (0.5-10):(0.5-10):1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 5-20:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 200-400 r / min, the rotation speed of the ball mill jar is 200-400 r / min, the rotation speed of the large disc is 0.5-2 r / min, and the ball milling time is 30-100 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed. Specifically, the solid-liquid ratio of the initial mixture and the wet milling solvent can be, for example, but not limited to, any one or a range between any two of 100g:20mL, 100g:40mL, 100g:60mL, 100g:80mL, 100g:100mL; the ball-to-material ratio can be, for example, but not limited to, any one or a range between any two of 5:1, 10:1, 15:1, 20:1; and the rotational speed of the large disc (i.e., the revolution speed) can be, for example, but not limited to, any one or a range between 200r / min, 250r / min, 300r / min, 350r / min, 400r / min. The range between the two; the rotational speed of the ball mill jar (i.e., the rotational speed) can be, for example, but not limited to, any one or any two of 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min; the tumbling speed of the large disc can be, for example, but not limited to, any one or any two of 0.5 r / min, 1 r / min, 1.5 r / min, 2 r / min; the ball milling time can be, for example, but not limited to, any one or any two of 30 h, 40 h, 50 h, 60 h, 70 h, 80 h, 90 h, 100 h;

[0054] Preferably, in step S3, the drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤ 1×10⁻⁶. -3The drying time is 5–10 h; the pressing and molding process uses steel molds; the pressing pressure is 100–350 MPa, and the holding time is 30–120 s; sieving is done using a 325–400 mesh sieve. Specifically, the drying time can be, for example, but not limited to, any one or any two of 5 h, 6 h, 7 h, 8 h, 9 h, 10 h; the pressing pressure can be, for example, but not limited to, any one or any two of 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa; the holding time can be, for example, but not limited to, any one or any two of 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 120 s.

[0055] Preferably, in step S4, the vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; Heat to the sintering temperature at a heating rate of 3–10 °C / min and hold for 180–420 min; When evacuating, first evacuate, then fill with argon protective gas for furnace cleaning, then evacuate again, repeating this process at least 5 times, finally evacuating to a vacuum degree ≤1×10⁻⁶. -3 Pa; the sintering temperature is 66-83% of the melting point of the refractory high-entropy alloy; the cooling is furnace cooling. Specifically, the heating rate can be, for example, but not limited to, any one or a range between any two of 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, and 10℃ / min; the holding time after reaching the sintering temperature can be, for example, but not limited to, any one or a range between any two of 180 min, 240 min, 300 min, 360 min, and 420 min.

[0056] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0057] Example 1

[0058] A TiZrMo refractory high-entropy alloy, with an atomic percentage ratio of Ti:Zr:Mo:Al:Nb = 1:1:1:1:1, has an entropy-enthalpy ratio of 1.663, an atomic radius difference of 4.69%, and a mixing enthalpy ΔH. mix The value is -17.12 kJ / mol, and the vacancy electron concentration (VEC) is 4.4.

[0059] The preparation method of the TiZrMo refractory high-entropy alloy in this embodiment includes the following steps:

[0060] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0061] The purity of the elemental powders is ≥99.9%. The D50 of Ti powder is 31.6 μm, Zr powder is 26.8 μm, Mo powder is 35.1 μm, Al powder is 22.4 μm, and Nb powder is 31.5 μm. The mixer is a three-dimensional mixer, and mixing is performed under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 2h. At this time, all elements are present in the preliminary mixture, and no alloyed powder has been formed. The D50 of the mixed powder is 29.7μm.

[0062] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0063] The wet grinding solvent is acetone, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:50mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of 1:2:1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 10:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 350 r / min, the rotation speed of the ball mill jar is 350 r / min, the rotation speed of the large disc is 1.0 r / min, and the ball milling time is 100 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed.

[0064] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0065] The drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 The drying time is 6 hours; the pressing and molding process is carried out using a steel mold; the pressing pressure is 200 MPa, and the holding time is 120 seconds; the sieve is made of 325 mesh.

[0066] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0067] The vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; Heat to 1700℃ at a heating rate of 5℃ / min and hold for 300min; During vacuuming, first evacuate the furnace, then purge with argon protective gas for cleaning, then evacuate again, repeating this process 5 times, finally evacuating to a vacuum degree ≤1×10⁻⁶. -3 Pa; cooling is achieved through furnace cooling.

[0068] The XRD results of the TiZrMoAlNb refractory high-entropy alloy prepared in this embodiment are as follows: Figure 1 As shown, its XRD diffraction pattern results indicate that the TiZrMoAlNb refractory high-entropy alloy has diffraction peaks of a BCC crystal structure solid solution and a Nb-rich phase.

[0069] Example 2

[0070] A TiZrMo refractory high-entropy alloy, with an atomic percentage ratio of Ti:Zr:Mo:Al:Nb = 0.5:1:1:1:1, an entropy enthalpy ratio of 1.571, an atomic radius difference of 4.91%, and a mixing enthalpy ΔH. mix The value is -17.98 kJ / mol, and the vacancy electron concentration (VEC) is 4.44.

[0071] The preparation method of the TiZrMo refractory high-entropy alloy in this embodiment includes the following steps:

[0072] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0073] The purity of the elemental powders is ≥99.9%. The D50 of Ti powder is 31.8 μm, Zr powder is 27.1 μm, Mo powder is 36.0 μm, Al powder is 22.9 μm, and Nb powder is 33.9 μm. The mixer is a three-dimensional mixer, and mixing is performed under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 2h. At this time, all elements are present in the preliminary mixture, and no alloyed powder has been formed. The D50 of the mixed powder is 29.6μm.

[0074] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0075] The wet grinding solvent is anhydrous ethanol, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:40mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of 5:5:1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 8:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 300 r / min, the rotation speed of the ball mill jar is 300 r / min, the rotation speed of the large disc is 0.5 r / min, and the ball milling time is 70 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed.

[0076] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0077] The drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 The drying time is 6 hours; the pressing and molding process is carried out using a steel mold; the pressing pressure is 200 MPa, and the holding time is 120 seconds; the sieve is made of 325 mesh.

[0078] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0079] The vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; Heat to 1750℃ at a heating rate of 5℃ / min and hold for 360min; During vacuuming, first evacuate the furnace, then purge with argon protective gas for furnace cleaning, then evacuate again, repeating this process 5 times, finally evacuating to a vacuum degree ≤1×10⁻⁶. -3 Pa; cooling is achieved through furnace cooling.

[0080] The Ti prepared in this embodiment 0.5 The XRD results of the ZrMoAlNb refractory high-entropy alloy are as follows: Figure 2 As shown, its XRD diffraction pattern results indicate that Ti 0.5 The ZrMoAlNb refractory high-entropy alloy exhibits BCC crystal structure solid solution diffraction peaks and an Nb-rich phase.

[0081] Example 3

[0082] A TiZrMo refractory high-entropy alloy, with an atomic percentage ratio of Ti:Zr:Mo:Cr:Nb = 1:1:1:0.5:1, has an entropy enthalpy ratio of 6.939, an atomic radius difference of 6.45%, and a mixing enthalpy ΔH. mix The concentration of vacancy electrons (VEC) is -4.54 kJ / mol, and the vacancy electron concentration (VEC) is 4.89.

[0083] The preparation method of the TiZrMo refractory high-entropy alloy in this embodiment includes the following steps:

[0084] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0085] The purity of the elemental powders is ≥99.9%. The D50 of Ti powder is 31.3 μm, Zr powder is 27.0 μm, Mo powder is 35.6 μm, Cr powder is 32.7 μm, and Nb powder is 31.4 μm. The mixer is a three-dimensional mixer, and mixing is performed under vacuum with a vacuum degree ≤1×10⁻⁶. -3Pa, mixing time is 2h. At this time, all elements are present in the preliminary mixture, and no alloyed powder has been formed. The D50 of the mixed powder is 30.14μm.

[0086] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0087] The wet grinding solvent is anhydrous ethanol, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:40mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of 5:5:1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 10:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 350 r / min, the rotation speed of the ball mill jar is 350 r / min, the rotation speed of the large disc is 0.5 r / min, and the ball milling time is 70 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed.

[0088] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0089] The drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 The drying time is 4.5 hours; the pressing and molding process is carried out using a steel mold; the pressing pressure is 180 MPa, and the holding time is 100 seconds; the sieve is made of 325 mesh.

[0090] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0091] The vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; Heat to 1800℃ at a heating rate of 5℃ / min and hold for 300min; When evacuating, first evacuate, then fill with argon protective gas for furnace cleaning, then evacuate again, repeating this process 5 times, finally evacuating to a vacuum degree ≤1×10 -3 Pa; cooling is achieved through furnace cooling.

[0092] The TiZrMoCr prepared in this embodiment 0.5 XRD results of Nb refractory high-entropy alloys are as follows: Figure 3 As shown, its XRD diffraction pattern results indicate that TiZrMoCr 0.5 The Nb refractory high-entropy alloy exhibits diffraction peaks of a BCC crystal structure solid solution and an Nb-rich phase.

[0093] Comparative Example 1

[0094] A TiZrMo refractory high-entropy alloy, with an atomic percentage ratio of Ti:Zr:Mo:Al:Cr = 1:1:1:2:1, has an entropy enthalpy ratio of 1.035, an atomic radius difference of 6.55%, and a mixing enthalpy ΔH. mix The concentration of vacancy electrons (VEC) is -23.00 kJ / mol, and the vacancy electron concentration is 4.33.

[0095] The preparation method of the TiZrMo-based refractory high-entropy alloy in this comparative example includes the following steps:

[0096] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0097] The purity of the elemental powders is ≥99.9%. The D50 of Ti powder is 32.5 μm, Zr powder is 27.3 μm, Mo powder is 36.4 μm, Al powder is 23.1 μm, and Cr powder is 33.1 μm. The mixer is a three-dimensional mixer, and mixing is performed under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 3h. At this time, all elements are present in the preliminary mixture, and no alloyed powder has been formed. The D50 of the mixed powder is 30.6μm.

[0098] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0099] The wet grinding solvent is anhydrous ethanol, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:50mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of 5:5:1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 10:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 300 r / min, the rotation speed of the ball mill jar is 300 r / min, the rotation speed of the large disc is 0.5 r / min, and the ball milling time is 80 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed.

[0100] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank.

[0101] The drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 The drying time is 6 hours; the pressing and molding process is carried out using a steel mold; the pressing pressure is 200 MPa, and the holding time is 100 seconds; the sieve is made of 325 mesh.

[0102] S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0103] The vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; Heat to 1600℃ at a heating rate of 5℃ / min and hold for 300min; When evacuating, first evacuate, then purge with argon protective gas for furnace cleaning, then evacuate again, repeating this process 5 times, finally evacuating to a vacuum degree ≤1×10⁻⁶. -3 Pa; cooling is achieved through furnace cooling.

[0104] The XRD results of the TiZrMoAl2Cr refractory high-entropy alloy prepared in this comparative example are as follows: Figure 4 As shown, its XRD diffraction pattern results indicate that the TiZrMoAl2Cr refractory high-entropy alloy is not a BCC crystal structure solid solution, but rather amorphous, and exhibits significant brittle cracking after solid-state sintering, making it difficult to form.

[0105] Comparative Example 2

[0106] A TiZrMo refractory high-entropy alloy, with an atomic percentage ratio of Ti:Zr:Mo:Al:Cr = 1:1:1:2:1, has an entropy enthalpy ratio of 1.035, an atomic radius difference of 6.55%, and a mixing enthalpy ΔH. mix The concentration of vacancy electrons (VEC) is -23.00 kJ / mol, and the vacancy electron concentration is 4.33.

[0107] The preparation method of the TiZrMo-based refractory high-entropy alloy in this comparative example includes the following steps:

[0108] S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture;

[0109] The purity of the elemental powders is ≥99.9%. The D50 of Ti powder is 32.5 μm, Zr powder is 27.3 μm, Mo powder is 36.4 μm, Al powder is 23.1 μm, and Cr powder is 33.1 μm. The mixer is a three-dimensional mixer, and mixing is performed under vacuum with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 3h. At this time, all elements are present in the preliminary mixture, and no alloyed powder has been formed. The D50 of the mixed powder is 30.6μm.

[0110] S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder.

[0111] The wet grinding solvent is anhydrous ethanol, and the solid-liquid ratio of the initial mixture to the wet grinding solvent is 100g:50mL. The grinding balls are stainless steel balls of different sizes, with diameters of 20mm, 10mm, and 6mm, and a mass ratio of 5:5:1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of 10:1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 300 r / min, the rotation speed of the ball mill jar is 300 r / min, the rotation speed of the large disc is 0.5 r / min, and the ball milling time is 80 h; during high-energy ball milling, the ball mill jar is removed every 5 h, and under the protection of inert gas, the powder in the jar body, including the inner wall and the jar cover, is scraped into the bottom of the jar to allow the powder to be fully alloyed.

[0112] S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it and then sieve the powder to obtain the pre-made powder.

[0113] The drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 Pa, drying time is 6 hours; sieve is made using a 325 mesh screen.

[0114] S4. After vacuum arc melting of the pre-made powder, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

[0115] The vacuum arc melting process is as follows: After loading the pre-made powder into the non-consumable vacuum arc melting furnace and closing the furnace door, the sample chamber is evacuated: First, the mechanical pump is turned on, and when the vacuum degree is ≤5×10 -3 After Pa, the molecular pump is turned on, with a maximum pump frequency of 450 Hz, until the vacuum degree is ≤2×10⁻⁶. -3After the pressure reaches -0.05 MPa, the molecular pump is shut off, and then high-purity argon gas is introduced into the sample chamber to -0.05 MPa. This "vacuuming-argon purging" process is repeated five times to thoroughly remove oxygen from the furnace. Then, the pure titanium ingot is melted for 5 minutes to absorb the remaining oxygen. The raw material is then repeatedly melted five times, each time for 10 minutes, followed by a 5-minute interval before the next melting. The first melting uses a low current of 200 A for low-temperature melting to reduce the volatilization loss of volatile elements. After thorough mixing, the arc is stopped, and after the ingot cools, it is rotated 180° using a lever. This rotation operation is repeated after each subsequent melting process. To ensure uniform melting, the second to fifth melting processes are carried out at a controlled current of 270A for high-temperature melting, and an electromagnetic stirring function with a current of 1.5A is used to enhance alloy fluidity and ensure uniform composition. Finally, the molten circular ingot in the copper crucible is placed on the casting mold. After arc ignition, a low current of 180A is used for low-temperature preheating. Once the ingot turns red and is heated evenly, the current is instantly increased to 380A to melt the ingot. At the same time, the suction casting button is clicked to suction cast the liquid alloy into an 80×10×3mm rectangular mold to prevent premature solidification and casting defects. After cooling, the mold is removed to obtain a rectangular suction-cast alloy ingot.

[0116] The refractory high-entropy alloy TiZrMoAl2Cr prepared in this comparative example exhibited significant brittle cracking after melting, making it difficult to form.

[0117] The properties of the alloys prepared in Examples 1-3 and Comparative Example 1 are shown in Table 1. As can be seen from the examples and comparative examples, the properties of the alloys prepared by this invention are significantly better than those of the comparative example. Furthermore, this invention has the advantages of simple steps, easy composition control, high production efficiency, and near-net-shape forming. The prepared refractory high-entropy alloy has a stable microstructure and a density of less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of approximately 6.6–10.7 mg / cm³ at 800℃ for 12 hours. 2 It is low in cost and easy to apply on a large scale in industrial applications.

[0118] Table 1. Properties of alloys prepared in Examples 1-3 and Comparative Example 1

[0119]

[0120] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A TiZrMo-based refractory high-entropy alloy, characterized in that, It is composed of any two of the following by atomic percentage: 5-35% Al, 5-35% Cr, and 5-35% Nb, and 5-35% Ti, 5-35% Zr, and 5-35% Mo; the atomic radius difference of the refractory high-entropy alloy is δ≤6.6%, the alloy entropy enthalpy ratio is Ω≥1.1, and the mixing enthalpy ΔH mix The energy range is -18.0 to 5.0 kJ / mol, and the vacancy electron concentration (VEC) is <6.

87. The density of refractory high-entropy alloys is less than 7.00 g / cm³. 3 It has a Vickers hardness greater than 1400 HV, a room temperature compressive strength consistently above 980 MPa, an elongation at break greater than 10.8%, and an oxidation weight gain of less than 15.00 mg / cm³ at 800℃ for 12 hours. 2 .

2. A method for preparing the TiZrMo refractory high-entropy alloy according to claim 1, characterized in that, Includes the following steps: S1. Take the elemental powders according to the alloy composition ratio and mix them in a mixer to obtain a preliminary mixture; S2. Add the preliminary mixture, wet grinding solvent and grinding balls into the ball milling jar, and after vacuuming, perform high-energy ball milling to obtain refractory high-entropy alloy powder. S3. After drying the refractory high-entropy alloy powder in a drying oven, grind it, sieve the powder, and press it into a pressed blank. S4. After vacuum solid-state sintering of the pressed billet, it is cooled to below 100°C to obtain a refractory high-entropy alloy.

3. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S1, the purity of the elemental powder is ≥99.5%, and the particle size is <45 μm; mixing is carried out under vacuum, with a vacuum degree ≤1×10⁻⁶. -3 Pa, mixing time is 1~5 h.

4. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S2, the wet milling solvent is anhydrous ethanol and / or n-heptane and / or acetone, and the solid-liquid ratio of the preliminary mixture to the wet milling solvent is 100g:(20~100)mL.

5. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S2, the grinding balls are stainless steel balls of different sizes, with diameters of 20 mm, 10 mm, and 6 mm, and a mass ratio of (0.5~10):(0.5~10):

1. The high-energy ball mill uses an omnidirectional planetary ball mill with a ball-to-material ratio of (5~20):1, and the vacuum degree after vacuuming is ≤1×10⁻⁶. -3 Pa, the rotation speed of the large disc is 200~400 r / min, the rotation speed of the ball mill jar is 200~400 r / min, the rotation speed of the large disc is 0.5~2 r / min, and the ball milling time is 30~100h.

6. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S3, the drying process is carried out under vacuum in a drying oven, with a vacuum degree ≤1×10⁻⁶. -3 Pa, drying time is 5~10 h.

7. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S3, the pressing and forming is done by steel mold pressing; the pressing pressure is 100~350 MPa, the holding time is 30~120 s; and the sieving is done with a 325~400 mesh screen.

8. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 2, characterized in that, In step S4, the vacuum solid-state sintering process is as follows: the pressed billet is loaded into the sintering furnace, and a vacuum is drawn until the vacuum degree is ≤1×10⁻⁶. -3 Pa; heat to the sintering temperature at a heating rate of 3~10℃ / min and hold for 180~420 min.

9. The method for preparing the TiZrMo-based refractory high-entropy alloy according to claim 8, characterized in that, In step S4, the sintering temperature is 66-83% of the melting point of the refractory high-entropy alloy.

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