A high-strength, high-hardness, lightweight, high-entropy alloy and its preparation method

Abstract

This invention relates to a high-strength, high-hardness, lightweight, high-entropy alloy and its preparation method, specifically to a high-strength, high-hardness, lightweight, high-entropy alloy and its preparation method. The aim is to address the insufficient room-temperature strength and hardness of existing as-cast lightweight high-entropy alloys. The formula for this lightweight high-entropy alloy is (AlNbTiVCr). 100‑x B x Preparation method: 1. Weigh the raw materials according to the atomic ratio expressed in the formula; 2. Place the raw materials on the crucible of a vacuum non-consumable arc furnace; 3. Before melting, turn on the circulating cooling water, and separately place sponge titanium and aluminum particles in the crucible. After evacuating the vacuum, under the protection of an inert gas, first melt the sponge titanium and aluminum particles, and then melt (AlNbTiVCr) with different cobalt contents in sequence. 100‑x B x After melting, the ingot sample is cooled to obtain a button ingot sample; fourth, the button ingot sample is repeatedly melted and cooled to obtain a lightweight high-entropy alloy. This invention is used to prepare lightweight high-entropy alloys.

Description

Technical Field

[0001] This invention relates to the field of lightweight alloy technology, specifically to a high-strength, high-hardness (AlNbTiVCr) alloy. 100-x B x Lightweight high-entropy alloys and their preparation methods. Background Technology

[0002] The research and application of materials are increasingly trending towards lightweighting, with fields such as aerospace and military industries requiring alloy materials with superior mechanical properties. Traditional lightweight alloys, such as magnesium alloys, titanium alloys, and aluminum alloys, have achieved significant research results and have, to some extent, replaced traditional alloys. However, these lightweight alloys have varying degrees of limitations, such as low room temperature strength, low hardness, and poor room temperature plasticity, making it difficult to meet service requirements under extreme conditions. These shortcomings significantly hinder the widespread application of lightweight alloys in aerospace and military industries.

[0003] The emergence of the concept of high-entropy alloys has provided new insights into the research of high-strength and high-hardness lightweight alloys. High-entropy alloys, also known as multi-principal-element alloys, are characterized by high mixing entropy, severe lattice distortion, slow atomic diffusion, and a wide compositional design space. These characteristics contribute to their high strength, corrosion resistance, wear resistance, high temperature resistance, and high hardness. The application of metallic materials is trending towards lightweighting, and military, industrial, aerospace, and transportation fields urgently require high-performance lightweight alloy materials. Traditional lightweight alloys such as aluminum, titanium, and magnesium alloys are no longer sufficient to meet the demanding service environments due to their inherent limitations. Currently, research on lightweight high-entropy alloys is still in its early stages and lacks a clear definition. From the perspective of alloy density, they are mainly divided into three categories: those with a density below 3 g / cm³. 3 Secondly, the density is lower than 4.5 g / cm³. 3 Third, the density is less than 7g / cm³. 3 Current research on lightweight high-entropy alloys mainly focuses on FCC solid solution-based alloys. Due to factors such as slip systems and alloy preparation and processing, FCC-based high-entropy alloys are characterized by good room-temperature plasticity but insufficient strength. Therefore, researching a lightweight high-entropy alloy with excellent mechanical properties is of great value for providing better lightweight alloy materials for future aerospace, military, and other fields, and for further exploring the practical applications of high-entropy alloys. Summary of the Invention

[0004] The present invention aims to address the problem of insufficient room temperature strength and hardness of existing cast lightweight high-entropy alloys, and to provide a high-strength, high-hardness lightweight high-entropy alloy and its preparation method.

[0005] This invention relates to a high-strength, high-hardness, lightweight, high-entropy alloy, the expression of which is (AlNbTiVCr). 100-xB x , where 0≤x≤2.

[0006] The lightweight high-entropy alloy is made from raw materials with the following atomic percentages: Al 19.6%–20%, Nb 19.6%–20%, Ti 19.6%–20%, V 19.6%–20%, Cr 19.6%–20%, and B 0.5%–2%, with the sum of the above atomic percentages being 100%.

[0007] The present invention also provides a method for preparing the above-mentioned high-strength, high-hardness, lightweight, high-entropy alloy, the specific steps of which are as follows:

[0008] I. According to the expression (AlNbTiVCr) 100-x B x The atomic ratio of raw materials is weighed to ensure that the composition ratio error is less than 0.1%; where 0 ≤ x ≤ 2;

[0009] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0010] 3. Before melting, turn on the circulating cooling water and place sponge titanium and aluminum particles in a crucible. After evacuation, under the protection of inert gas, melt the sponge titanium and aluminum particles first to absorb the residual oxygen in the vacuum melting furnace; then melt the raw materials. After melting, cool to obtain button ingot samples.

[0011] 4. Repeatedly melt the button ingot sample 5-6 times. When melting for the last time, gradually increase the current of the electric arc furnace to 550A, then gradually decrease it to 450A. Subsequently, decrease the current by 50A every 15 seconds. During this process, the arc gun moves continuously in a circular trajectory. When the current drops to 150A, turn off the power and cool to obtain (AlNbTiVCr). 100-x Co x High-entropy alloys.

[0012] Furthermore, in step one, the raw materials are Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0013] Furthermore, in step two, the raw materials need to be polished before being placed in the crucible, and then cleaned and dried.

[0014] The polishing is done using silicon carbide sandpaper.

[0015] The cleaning process involves placing the raw materials in acetone and ultrasonically cleaning them for 10–20 minutes. The ultrasonic conditions are: power 120W, frequency 36kHz.

[0016] Furthermore, in step three, the circulating cooling water flow rate is 1–3 m / s.

[0017] Furthermore, in step three, the current of the electric arc furnace is gradually increased from 90A to 600A during the smelting process.

[0018] Furthermore, in step four, the button ingot sample is rotated 180° before each melting process.

[0019] Furthermore, in step four, the current of the electric arc furnace during the smelting process is 90A to 600A, and the time is 2min to 8min.

[0020] The beneficial effects of this invention are:

[0021] 1. By adjusting the content of element B, the volume fraction and distribution of intermetallic compound phases can be controlled. At the same time, element B increases the atomic radius difference in the alloy system, thereby obtaining high strength and high hardness.

[0022] 2. (AlNbTiVCr) prepared by the method of this invention 100-x B x In lightweight high-entropy alloys, B and Ti exhibit the largest electronegativity difference; a larger electronegativity difference indicates a greater ease of forming intermetallic compounds. Simultaneously, B and Ti possess the most negative enthalpy of mixing—28 kJ / mol; a more negative enthalpy of mixing signifies stronger inter-element attraction and a greater ability to form intermetallic compounds.

[0023] 3. In the method of this invention, a portion of B dissolves into AlNbTiVCr to form a saturated solid solution, resulting in solid solution strengthening; B and Ti form dispersed intermetallic compounds, resulting in precipitated phase strengthening. The (AlNbTiVCr) prepared by this invention... 100-x B x Lightweight high-entropy alloys exhibit high strength and high hardness under the combined effects of solid solution strengthening and precipitated phase strengthening. These lightweight alloys have high compressive strength of 1520.8MPa to 1844.4MPa and high hardness of 574.8HV to 693.4HV.

[0024] 4. The alloy prepared by the method of this invention exhibits improved properties. Bo (B) has a relatively negative enthalpy of mixing with Al, Nb, Ti, V, and Cr, readily forming intermetallic compounds. These fine intermetallic compound phases hinder grain boundary movement, giving the alloy sufficient strength and hardness. Al, Ti, and Nb provide a certain degree of deformability; Cr, V, and Nb provide strength support; and the formation of intermetallic compound phases by B and Ti, with their fine dispersion throughout the alloy matrix, enhances the alloy's strength and hardness. The fracture strain of the alloy after adding B is consistently above 14.3%, and the theoretical density of this lightweight alloy is 5.73–5.77 g / cm³. 3 It is a lightweight, high-entropy alloy with great development potential. Attached Figure Description

[0025] Figure 1 (AlNbTiVCr) 100-x B x XRD pattern of a lightweight high-entropy alloy;

[0026] Figure 2 (AlNbTiVCr) 100-x B x Scanning electron microscopy (SEM) image of a lightweight, high-entropy alloy;

[0027] Figure 3 (AlNbTiVCr) 100-x B x Scanning electron microscopy (SEM) image of a lightweight, high-entropy alloy;

[0028] Figure 4 (AlNbTiVCr) 100-x B x Scanning electron microscopy (SEM) image of a lightweight, high-entropy alloy;

[0029] Figure 5 (AlNbTiVCr) 100-x B x Vickers hardness of lightweight high-entropy alloys;

[0030] Figure 6 (AlNbTiVCr) 100-x B x Room temperature compressive mechanical properties of lightweight high-entropy alloys. Detailed Implementation

[0031] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0032] Specific Implementation Method 1: This implementation method uses a high-strength, high-hardness, lightweight, high-entropy alloy, the expression of which is (AlNbTiVCr). 100-x Bx , where 0≤x≤2.

[0033] B readily forms intermetallic compounds with Al, Nb, Ti, V, and Cr. The enthalpy of mixing between B and Ti is similar to that between B and Nb. The atomic radius difference between Nb and Cr is relatively large. These elements readily form in-situ self-generated intermetallic compound phases. This alloy is produced by vacuum arc melting. Under the conditions of rapid cooling and non-equilibrium solidification, the microstructure is fine, which easily forms a dispersed intermetallic compound phase, providing sufficient strength and hardness to the alloy.

[0034] In this invention, V, B, Ti, Cr, and Nb are all transition metals with significant differences in atomic radii, leading to severe lattice distortion and making it easier to form intermetallic compounds, thus improving the strength and hardness of the alloy. The six elements in the alloy provide a large mixing entropy, which can stabilize the formation of solid solutions.

[0035] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the lightweight high-entropy alloy is made from raw materials with the following atomic percentages: Al 19.6%–20%, Nb 19.6%–20%, Ti 19.6%–20%, V 19.6%–20%, Cr 19.6%–20%, and B 0.5%–2%, with the sum of all atomic percentages being 100%. Everything else is the same as in Specific Implementation Method One.

[0036] Specific Implementation Method 3: The preparation method of the high-strength, high-hardness, lightweight, high-entropy alloy in this implementation method includes the following specific steps:

[0037] I. According to the expression (AlNbTiVCr) 100-x B x The atomic ratio of raw materials is weighed to ensure that the composition ratio error is less than 0.1%; where 0 ≤ x ≤ 2;

[0038] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace. Place B and Ti, which have the highest enthalpy of mixing, at the two ends respectively. Place the other raw materials in the middle in order of increasing melting point from top to bottom. The higher the enthalpy of mixing between elements, the stronger the ability to form intermetallic compounds. Separating the two elements with the highest enthalpy of mixing according to their enthalpy can prevent all elements from forming intermetallic compounds, ensure sufficient diffusion of elements and formation of solid solutions in the alloy, and result in a more uniform microstructure.

[0039] 3. Before melting, turn on the circulating cooling water and place sponge titanium and aluminum particles in a crucible. After evacuation, under the protection of inert gas, melt the sponge titanium and aluminum particles first to absorb the residual oxygen in the vacuum melting furnace; then melt the raw materials. After melting, cool to obtain button ingot samples.

[0040] 4. Repeatedly melt the button ingot sample 5-6 times. When melting for the last time, gradually increase the current of the electric arc furnace to 550A, then gradually decrease it to 450A. Subsequently, decrease the current by 50A every 15 seconds. During this process, the arc gun moves continuously in a circular trajectory. When the current drops to 150A, turn off the power and cool to obtain (AlNbTiVCr). 100-x Co x High-entropy alloys.

[0041] This method uses vacuum arc melting. Because the vacuum arc melting furnace is equipped with a water-cooled copper crucible, the extremely fast cooling rate gives the high-entropy alloy high strength and high hardness.

[0042] Step four, the operation at the final stage of melting, ensures that the ingot in the water-cooled copper crucible solidifies as slowly as possible, reduces stress in the alloy, and ensures diffusion and compositional uniformity.

[0043] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method Three in that the raw materials in step one are Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregularly shaped sheet-like B with a purity greater than 99.9%. Everything else is the same as in Specific Implementation Method Three.

[0044] In this embodiment, Ti is selected as sponge titanium. Sponge titanium has a porous structure and a large surface area, and its porous structure makes it easier to melt during the smelting process.

[0045] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods Three or Four in that the raw materials in step two need to be polished before being placed in the crucible, and then cleaned and dried. Everything else is the same as in Specific Implementation Methods Three or Four.

[0046] Polishing is done to remove oxide scale and surface impurities.

[0047] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the polishing is performed using silicon carbide sandpaper. Everything else is the same as in Specific Implementation Method Five.

[0048] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Five in that the cleaning involves placing the raw materials in acetone and ultrasonically cleaning them for 10-20 minutes. The ultrasonic conditions are: power 120W, frequency 36KHz. Everything else is the same as in Specific Implementation Method Five.

[0049] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods Three to Seven in that the circulating cooling water flow rate in step three is 1–3 m / s. Everything else is the same as in Specific Implementation Methods Three to Seven.

[0050] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Three to Eight in that: in step four, the button ingot sample is rotated 180° before each melting. Everything else is the same as in Specific Implementation Methods Three to Eight.

[0051] To ensure the uniformity of the alloy composition in the ingot.

[0052] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Three to Nine in that the current of the electric arc furnace during the smelting process in step four is 90A to 600A, and the time is 2-8 minutes. Everything else is the same as in Specific Implementation Methods Three to Nine.

[0053] The embodiments of the present invention will be described in detail below. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation schemes and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0054] Example 1:

[0055] This embodiment features high strength and high hardness (AlNbTiVCr). 100-x B x The lightweight high-entropy alloy has the following atomic percentages of each element: Al 19.98%, Nb 19.98%, Ti 19.98%, V 19.98%, Cr 19.98%, and is labeled as Al19.98Nb19.98Ti19.98V19.98Cr19.98B0.1 lightweight high-entropy alloy.

[0056] Step 1: Prepare the required metal raw materials according to the above element ratios: Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0057] All raw materials require pretreatment, including polishing, cleaning, and drying. Use 400-grit silicon carbide sandpaper to polish the raw materials to remove impurities and oxide scale from the surface. Place the raw materials in batches in acetone and then place them in an ultrasonic cleaner with a power of 120W and a frequency of 36KHz for 10 minutes. After cleaning, use an 800W hair dryer to dry the raw materials.

[0058] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0059] Separately place 60g of sponge titanium and 60g of aluminum granules in a crucible. Both the sponge titanium and aluminum granules can absorb residual oxygen in the furnace. A vacuum of 2×10⁻⁶ is then applied. -3 After the pressure reaches 0.05 MPa, argon gas is introduced to provide protection. Vacuuming continues during this process. After 10 minutes, the pre-vacuum valve and mechanical pump are turned off, and argon gas is introduced to reach 0.05 MPa again. This process is repeated twice. Before melting, the circulating cooling water is turned on at a flow rate of 3 m / s to ensure rapid heat removal from the bottom of the crucible. This allows the alloy to cool rapidly and achieve non-equilibrium solidification while melting continues. The arc-starting current is 90 A. 60 g of sponge titanium and 60 g of aluminum granules are melted first. During melting, the current is gradually increased to 600 A, and then the power is turned off. This process takes approximately 6 minutes. After melting, the sample is cooled to obtain a button ingot.

[0060] Step 3: Repeatedly melt the button ingot sample 5 times. Before each melting, use a flipping spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. To ensure the uniformity of composition, when melting for the last time, first gradually increase the current of the electric arc furnace to 550A, and then gradually decrease it to 450A. Subsequently, the current is reduced by 50A every 15 seconds. During this process, the electric arc gun moves continuously, and the trajectory is circular. When the current drops to 150A, turn off the power. After cooling, a high-strength and high-hardness Al20Nb20Ti20V20Cr20B0.1 lightweight high-entropy alloy is obtained.

[0061] Comparative Example 1:

[0062] The difference between this comparative example and Example 1 is as follows:

[0063] Step 2: Place the raw materials on the crucible of the vacuum non-consumable arc furnace, arranging them in order of increasing melting point from top to bottom;

[0064] Step 3: Melt the button ingot sample repeatedly 5 times. Before each melting, use a turning spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. After melting, turn off the power and cool to obtain a high-strength and high-hardness Al20Nb20Ti20V20Cr20B0.1 lightweight high-entropy alloy.

[0065] The other steps and parameters are the same as in Example 1.

[0066] Example 2:

[0067] This embodiment features high strength and high hardness (AlNbTiVCr). 100-x B xThe lightweight high-entropy alloy has the following atomic percentages: Al 19.9%, Nb 19.9%, Ti 19.9%, V 19.9%, Cr 19.9%, and B 0.5%, and is labeled as Al19.9Nb19.9Ti19.9V19.9Cr19.9B0.5 lightweight high-entropy alloy.

[0068] Step 1: Prepare the required metal raw materials according to the above element ratios: Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0069] All raw materials require pretreatment, including polishing, cleaning, and drying. Use 400-grit silicon carbide sandpaper to polish the raw materials to remove impurities and oxide scale from the surface. Place the raw materials in batches in acetone and then place them in an ultrasonic cleaner with a power of 120W and a frequency of 36KHz for 10 minutes. After cleaning, use an 800W hair dryer to dry the raw materials.

[0070] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0071] Separately place 60g of sponge titanium and 60g of aluminum granules in a crucible. Both the sponge titanium and aluminum granules can absorb residual oxygen in the furnace. A vacuum of 2×10⁻⁶ is then applied. -3 After the pressure reaches 0.05 MPa, argon gas is introduced to provide protection. Vacuuming continues during this process. After 10 minutes, the pre-vacuum valve and mechanical pump are turned off, and argon gas is introduced to reach 0.05 MPa again. This process is repeated twice. Before melting, the circulating cooling water is turned on at a flow rate of 3 m / s to ensure rapid heat removal from the bottom of the crucible. This allows the alloy to cool rapidly and achieve non-equilibrium solidification while melting continues. The arc-starting current is 90 A. 60 g of sponge titanium and 60 g of aluminum granules are melted first. During melting, the current is gradually increased to 600 A, and then the power is turned off. This process takes approximately 6 minutes. After melting, the sample is cooled to obtain a button ingot.

[0072] Step 3: Repeatedly melt the button ingot sample 5 times. Before each melting, use a flipping spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. To ensure the uniformity of composition, when melting for the last time, first gradually increase the current of the electric arc furnace to 550A, and then gradually decrease it to 450A. Subsequently, the current is reduced by 50A every 15 seconds. During this process, the electric arc gun moves continuously, and the trajectory is circular. When the current drops to 150A, turn off the power. After cooling, a high-strength and high-hardness Al19.9Nb19.9Ti19.9V19.9Cr19.9B0.5 lightweight high-entropy alloy is obtained.

[0073] Example 3:

[0074] This embodiment features high strength and high hardness (AlNbTiVCr). 100-x B x The lightweight high-entropy alloy has the following atomic percentages: Al 19.8%, Nb 19.8%, Ti 19.8%, V 19.8%, Cr 19.8%, and B 1%, and is labeled as Al19.8Nb19.8Ti19.8V19.8Cr19.8B1 lightweight high-entropy alloy.

[0075] Step 1: Prepare the required metal raw materials according to the above element ratios: Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0076] All raw materials require pretreatment, including polishing, cleaning, and drying. Use 400-grit silicon carbide sandpaper to polish the raw materials to remove impurities and oxide scale from the surface. Place the raw materials in batches in acetone and then place them in an ultrasonic cleaner with a power of 120W and a frequency of 36KHz for 10 minutes. After cleaning, use an 800W hair dryer to dry the raw materials.

[0077] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0078] Separately place 60g of sponge titanium and 60g of aluminum granules in a crucible. Both the sponge titanium and aluminum granules can absorb residual oxygen in the furnace. A vacuum of 2×10⁻⁶ is then applied. -3After the pressure reaches 0.05 MPa, argon gas is introduced to provide protection. Vacuuming continues during this process. After 10 minutes, the pre-vacuum valve and mechanical pump are turned off, and argon gas is introduced to reach 0.05 MPa again. This process is repeated twice. Before melting, the circulating cooling water is turned on at a flow rate of 3 m / s to ensure rapid heat removal from the bottom of the crucible. This allows the alloy to cool rapidly and achieve non-equilibrium solidification while melting continues. The arc-starting current is 90 A. 60 g of sponge titanium and 60 g of aluminum granules are melted first. During melting, the current is gradually increased to 600 A, and then the power is turned off. This process takes approximately 6 minutes. After melting, the sample is cooled to obtain a button ingot.

[0079] Step 3: Repeatedly melt the button ingot sample 5 times. Before each melting, use a flipping spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. To ensure the uniformity of composition, when melting for the last time, first gradually increase the current of the electric arc furnace to 550A, and then gradually decrease it to 450A. Subsequently, the current is reduced by 50A every 15 seconds. During this process, the electric arc gun moves continuously, and the trajectory is circular. When the current drops to 150A, turn off the power. After cooling, a high-strength and high-hardness Al19.8Nb19.8Ti19.8V19.8Cr19.8B1 lightweight high-entropy alloy is obtained.

[0080] Example 4:

[0081] This embodiment features high strength and high hardness (AlNbTiVCr). 100-x B x The lightweight high-entropy alloy has the following atomic percentages: Al 19.7%, Nb 19.7%, Ti 19.7%, V 19.7%, Cr 19.7%, and B 1.5%, and is labeled as Al19.7Nb19.7Ti19.7V19.7Cr19.7B1.5 lightweight high-entropy alloy.

[0082] Step 1: Prepare the required metal raw materials according to the above element ratios: Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0083] All raw materials require pretreatment, including polishing, cleaning, and drying. Use 400-grit silicon carbide sandpaper to polish the raw materials to remove impurities and oxide scale from the surface. Place the raw materials in batches in acetone and then place them in an ultrasonic cleaner with a power of 120W and a frequency of 36KHz for 10 minutes. After cleaning, use an 800W hair dryer to dry the raw materials.

[0084] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0085] Separately place 60g of sponge titanium and 60g of aluminum granules in a crucible. Both the sponge titanium and aluminum granules can absorb residual oxygen in the furnace. A vacuum of 2×10⁻⁶ is then applied. -3 After the pressure reaches 0.05 MPa, argon gas is introduced as a protective gas. Vacuuming continues during this process. After 5-10 minutes, the pre-vacuum valve and mechanical pump are turned off, and argon gas is introduced again to 0.05 MPa. This process is repeated twice. Before melting, the circulating cooling water is turned on at a flow rate of 3 m / s to ensure rapid heat removal from the bottom of the crucible. This allows the alloy to cool rapidly and achieve non-equilibrium solidification while melting continues. The arc-starting current is 90 A. 60 g of sponge titanium and 60 g of aluminum granules are melted first. During melting, the current is gradually increased to 600 A, then the power is turned off. This process takes approximately 6 minutes. After melting, the sample is cooled to obtain a button ingot.

[0086] Step 3: Repeatedly melt the button ingot sample 5 times. Before each melting, use a flipping spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. To ensure the uniformity of composition, when melting for the last time, first gradually increase the current of the electric arc furnace to 550A, and then gradually decrease it to 450A. Subsequently, the current is reduced by 50A every 15 seconds. During this process, the electric arc gun moves continuously, and the trajectory is circular. When the current drops to 150A, turn off the power. After cooling, a high-strength and high-hardness Al19.7Nb19.7Ti19.7V19.7Cr19.7B1.5 lightweight high-entropy alloy is obtained.

[0087] Example 5:

[0088] This embodiment features high strength and high hardness (AlNbTiVCr). 100-x B x The lightweight high-entropy alloy has the following atomic percentages: Al 19.6%, Nb 19.6%, Ti 19.6%, V 19.6%, Cr 19.6%, and B 2%, and is labeled as Al19.6Nb19.6Ti19.6V19.6Cr19.6B2 lightweight high-entropy alloy.

[0089] Step 1: Prepare the required metal raw materials according to the above element ratios: Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

[0090] All raw materials require pretreatment, including polishing, cleaning, and drying. Use 400-grit silicon carbide sandpaper to polish the raw materials to remove impurities and oxide scale from the surface. Place the raw materials in batches in acetone and then place them in an ultrasonic cleaner with a power of 120W and a frequency of 36KHz for 10 minutes. After cleaning, use an 800W hair dryer to dry the raw materials.

[0091] 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

[0092] Separately place 60g of sponge titanium and 60g of aluminum granules in a crucible. Both the sponge titanium and aluminum granules can absorb residual oxygen in the furnace. A vacuum of 2×10⁻⁶ is then applied. -3 After the pressure reaches 0.05 MPa, argon gas is introduced as a protective gas. Vacuuming continues during this process. After 5-10 minutes, the pre-vacuum valve and mechanical pump are turned off, and argon gas is introduced again to 0.05 MPa. This process is repeated twice. Before melting, the circulating cooling water is turned on at a flow rate of 3 m / s to ensure rapid heat removal from the bottom of the crucible. This allows the alloy to cool rapidly and achieve non-equilibrium solidification while melting continues. The arc-starting current is 90 A. 60 g of sponge titanium and 60 g of aluminum granules are melted first. During melting, the current is gradually increased to 600 A, then the power is turned off. This process takes approximately 6 minutes. After melting, the sample is cooled to obtain a button ingot.

[0093] Step 3: Repeatedly melt the button ingot sample 5 times. Before each melting, use a flipping spoon to turn the button ingot sample over. During the melting process, the current of the electric arc furnace is 550A, and the melting time is 5 minutes each time. To ensure the uniformity of composition, when melting for the last time, first gradually increase the current of the electric arc furnace to 550A, and then gradually decrease it to 450A. Subsequently, the current is reduced by 50A every 15 seconds. During this process, the electric arc gun moves continuously, and the trajectory is circular. When the current drops to 150A, turn off the power. After cooling, a high-strength and high-hardness Al19.6Nb19.6Ti19.6V19.6Cr19.6B2 lightweight high-entropy alloy is obtained.

[0094] Phase analysis of the lightweight high-entropy alloys prepared in Examples 1-5 was performed using an Empyrean intelligent X-ray diffractometer with scanning angles ranging from 20° to 100°. Figure 1 The images show the XRD patterns of the lightweight high-entropy alloys in Examples 1-5, where B0.1 represents Example 1, B0.5 represents Example 2, B1 represents Example 3, B1.5 represents Example 4, and B2 represents Example 5. Figure 1 It can be seen that the alloys prepared in Examples 1-5 exhibit BCC solid solution and TiB intermetallic compound phase structures.

[0095] The microstructure of the lightweight high-entropy alloys prepared in Examples 1-5 was analyzed using a Merlin Bmpact Zeiss field emission scanning electron microscope with an accelerating voltage of 20V-30KV. Figure 2 This is a scanning electron microscope image of the lightweight high-entropy alloy prepared in Example 1. Figure 3 The image shows a scanning electron microscope image of the lightweight high-entropy alloy prepared in Comparative Example 1. Figure 4 The image shows the microstructure of the lightweight high-entropy alloy prepared in Example 2 using a scanning electron microscope. Comparison reveals that the lightweight high-entropy alloys prepared in Examples 1 and 2 exhibit higher uniformity.

[0096] according to Figure 2 and Figure 4 As can be seen, the microstructure exhibits a typical dendritic structure, containing dark gray BCC solid solution and light gray TiB intermetallic compound phase. The microstructures of Examples 3, 4, and 5 are similar to those of Example 1.

[0097] The lightweight high-entropy alloys prepared in Examples 1-5 were subjected to Vickers hardness testing using an FM-700 Vickers hardness tester. The load was 200g, the testing time per point was 10s, and 15 points were tested per sample. The maximum and minimum values ​​were removed, and the average value was taken as the Vickers hardness value for the final example. Figure 5 As can be seen from this, (AlNbTiVCr) is used in this invention. 100-x B x The lightweight high-entropy alloys exhibited high Vickers hardness, with the highest Vickers hardness value reaching 754 HV. The room temperature compression properties of the lightweight high-entropy alloys prepared in Examples 1-5 were tested using an electronic universal testing machine at a loading rate of 0.5 mm / min. Figure 6 The blue curve represents the stress as the boron content increases, and the red curve represents the strain as the boron content increases. Figure 6 It can be seen that the compressive strength of alloy Al19.7Nb19.7Ti19.7V19.7Cr19.7B1.5 is 1904 MPa, and the fracture strength of all five alloy components is greater than 1500 MPa (AlNbTiVCr). 100-x B x Lightweight high-entropy alloys exhibit high room-temperature compressibility. The high strength and high hardness are mainly due to the severe lattice distortion caused by boron and the large atomic radius difference leading to the formation of TiB intermetallic compound phases. The melting of 60g of sponge titanium and 60g of aluminum particles during the smelting process can provide an oxygen-free environment for the alloy melting process, ensuring the purity of the alloy composition and laying the foundation for the high compressibility of the alloy.

Claims

1. A high-strength, high-hardness, lightweight, high-entropy alloy, characterized in that... This lightweight, high-entropy alloy is expressed as (AlNbTiVCr). 100-x B x , where 0.1≤ x ≤2; The preparation method of the high-strength, high-hardness, lightweight, high-entropy alloy includes the following steps: I. According to the expression (AlNbTiVCr) 100-x B x Weigh the raw materials according to their atomic ratio to ensure that the composition ratio error is less than 0.1%; where 0.1 ≤ x ≤2; 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

3. Before smelting, turn on the circulating cooling water, and separately place sponge titanium and aluminum particles in the crucible. After evacuating the vacuum, under the protection of inert gas, first melt the sponge titanium and aluminum particles, and then melt (AlNbTiVCr) with different cobalt contents in sequence. 100-x B x After melting, the button ingot samples were obtained by cooling.

4. Repeatedly melt the button ingot sample 5-6 times. When melting for the last time, gradually increase the current of the electric arc furnace to 550A, then gradually decrease it to 450A. Subsequently, decrease the current by 50A every 15 seconds. During this process, the arc gun moves continuously in a circular trajectory. When the current drops to 150A, turn off the power and cool to obtain (AlNbTiVCr). 100-x Co x High-entropy alloys.

2. The high-strength, high-hardness, lightweight, high-entropy alloy according to claim 1, characterized in that... The lightweight high-entropy alloy is made from the following raw materials in atomic percentages: Al 19.6%~20%, Nb 19.6%~20%, Ti 19.6%~20%, V 19.6%~20%, Cr 19.6%~20%, and B 0.5%~2%, with the sum of the above atomic percentages being 100%.

3. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy as described in claim 1, characterized in that... The method includes the following steps: I. According to the expression (AlNbTiVCr) 100-x B x Weigh the raw materials according to their atomic ratio to ensure that the composition ratio error is less than 0.1%; where 0.1 ≤ x ≤2; 2. Place the raw materials on the crucible of the vacuum non-consumable arc furnace, place B and Ti with the highest mixing enthalpy at both ends, and place the other raw materials in the middle in order of increasing melting point from top to bottom.

3. Before smelting, turn on the circulating cooling water, and separately place sponge titanium and aluminum particles in the crucible. After evacuating the vacuum, under the protection of inert gas, first melt the sponge titanium and aluminum particles, and then melt (AlNbTiVCr) with different cobalt contents in sequence. 100-x B x After melting, the button ingot samples were obtained by cooling.

4. Repeatedly melt the button ingot sample 5-6 times. When melting for the last time, gradually increase the current of the electric arc furnace to 550A, then gradually decrease it to 450A. Subsequently, decrease the current by 50A every 15 seconds. During this process, the arc gun moves continuously in a circular trajectory. When the current drops to 150A, turn off the power and cool to obtain (AlNbTiVCr). 100-x Co x High-entropy alloys.

4. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 3, characterized in that... In step one, the raw materials are Al particles with a purity greater than 99.9%, Nb particles with a purity greater than 99.9%, V particles with a purity greater than 99.9%, Cr particles with a purity greater than 99.9%, sponge titanium with a purity greater than 99.9%, and irregular sheet-like B with a purity greater than 99.9%.

5. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 3 or 4, characterized in that... In step two, the raw materials need to be polished before being placed in the crucible, and then cleaned and dried.

6. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 5, characterized in that... The polishing is done using silicon carbide sandpaper.

7. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 5, characterized in that... The cleaning process involves placing the raw materials in acetone and ultrasonically cleaning them for 10-20 minutes under the following conditions: power 120W and frequency 36KHz.

8. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 5, characterized in that... In step three, the circulating cooling water flow rate is 1~3m / s.

9. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 8, characterized in that... In step four, the button ingot sample is rotated 180° before each melting process.

10. The method for preparing the high-strength, high-hardness, lightweight, high-entropy alloy according to claim 9, characterized in that... In step four, the current of the electric arc furnace during the smelting process is 90A~600A, and the time is 2min~8min.

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