TiZr-based high-entropy alloy with ultrahigh corrosion resistance and strong plasticity matching and preparation of TiZr-based high-entropy alloy

Abstract

The invention discloses a TiZr-based high-entropy alloy with ultrahigh corrosion resistance and strong plasticity matching and a preparation method of the TiZr-based high-entropy alloy, and belongs to the technical field of high-entropy alloys. The chemical formula of the high-entropy alloy is TiaZrbNbcVd according to atomic percent, a is larger than or equal to 25 and smaller than or equal to 65, b is larger than or equal to 12 and smaller than or equal to 35, c is larger than or equal to 0 and smaller than or equal to 35, d is larger than or equal to 0 and smaller than or equal to 35, a + b + c + d = 100, and c and d cannot be 0 at the same time. According to the preparation method, the matching high-entropy alloy with ultrahigh corrosion resistance and strong plasticity is prepared through burdening, pretreatment, smelting and forming. According to the invention, a plurality of pure metal elements are smelted to form a master alloy ingot, and the copper mold is cooled by cooling circulating water to cast and mold the alloy. The alloy material is of a single BCC phase structure, has good strength and plasticity matching and has the ultrahigh pitting resistance potential exceeding 7.0 VSCE. The preparation process is simple, and is suitable for industrial large-scale popularization and production practice.

Description

Technical Field

[0001] The present invention relates to the technical field of high entropy alloys, and in particular to a TiZr-based high entropy alloy with ultra-high corrosion resistance and strong-plasticity matching, and a preparation method thereof. Background Art

[0002] The rapid development of current science and technology has brought new challenges to the performance of materials. Traditional alloys such as stainless steel and titanium alloys have problems such as corrosion failure and environmental fracture damage in harsh environments. The development of alloys with ultra-high corrosion resistance and strong plasticity will provide guarantees for the innovative development of new engineering equipment in extreme environments.

[0003] High-entropy alloys (HEAs) have attracted considerable attention in materials science in recent years due to their unique compositional design and excellent comprehensive properties (such as high strength, hardness, corrosion resistance, and thermal stability). Therefore, the HEA concept offers the potential to achieve a balanced combination of corrosion resistance and strength / ductility. Unfortunately, in existing technologies, the diverse and complex interactions of elements alter the stability of the passive film on the alloy surface. Furthermore, interactions between different components affect the growth kinetics of the passive film, making it difficult to rapidly form the desired stable passive film on the alloy surface. Consequently, the pitting corrosion resistance of HEAs is suboptimal, failing to demonstrate their advantages over conventional alloys. Furthermore, recent studies have revealed that most HEAs exhibit significant performance trade-offs: for example, improved corrosion resistance is often accompanied by decreased ductility, while enhanced mechanical properties may compromise corrosion resistance. Furthermore, the complex phase structure (e.g., coexistence of multiple phases) of some HEAs leads to poor processing properties, making them difficult to meet the demands of industrial applications. While elements such as Ti, Zr, Nb, and V are commonly used in the design of corrosion-resistant alloys, research on these HEA systems remains insufficient. For example, some alloys have limited passivation ability in corrosive media and low pitting potentials; or due to unreasonable element ratios, the phase composition is unstable (such as the appearance of intermetallic compounds or amorphous phases), which in turn affects the uniformity of mechanical properties. In addition, the traditional preparation process is cumbersome and costly, which limits its large-scale production. Therefore, developing a high-entropy alloy system with ultra-high corrosion resistance, strong and ductile matching, and simple processing has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the existing technology, the purpose of the present invention is to provide a Ti-Zr-Nb-V series high-entropy alloy with ultra-high corrosion resistance and strong plasticity matching and a preparation method thereof. The high-entropy alloy prepared by the present invention has good strong plasticity matching, ultra-high pitting potential and excellent long-term corrosion resistance.

[0005] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0006] A TiZr-based high entropy alloy with ultra-high corrosion resistance and strong plasticity matching, characterized in that the chemical expression of the high entropy alloy is Ti a Zr b Nb c V d , where 25≤a≤65, 12≤b≤35, 0≤c≤35, 0≤d≤35, where a+b+c+d=100, and c and d cannot be 0 at the same time, and their sum 3≤c+d≤50.

[0007] The high entropy alloy according to claim 1, characterized in that: in the chemical expression of the high entropy alloy, 30≤a≤62, 15≤b≤31, 3≤c≤31, 3≤d≤31, and a+b+c+d=100.

[0008] The high entropy alloy according to claim 1 or 2, wherein the phase structure of the high entropy alloy is a single BCC phase.

[0009] The high entropy alloy according to claim 1, 2 or 3, wherein the high entropy alloy has a yield strength of 300 to 900 MPa, a tensile strength of 600 to 900 MPa, and an elongation after fracture greater than 10%.

[0010] The high entropy alloy according to claim 1, 2 or 3, wherein the self-corrosion current density of the high entropy alloy is less than 0.5 μA / cm 2 , pitting potential range is higher than 7000mV SCE , passivation range is greater than 7500mV SCE .

[0011] A preparation method according to any one of claims 1 to 5, characterized in that the TiZr-based high-entropy alloy having both high corrosion resistance and matched strength and ductility is synthesized by arc melting, and the alloy ingot melting process is carried out in an argon protective environment, and the specific steps are as follows:

[0012] S1. Ingredients

[0013] Descaling the pure metal raw material of the metal required for the high entropy alloy with ultra-high corrosion resistance and strong plasticity, and then weighing the raw materials of each element according to the chemical composition of the high entropy alloy;

[0014] S2. Melting

[0015] The weighed raw materials of S1 are melted by arc melting method. The raw materials are placed in the melting furnace and the vacuum is pumped to 4×10 -3Pa below, filled with argon for atmosphere protection; during smelting, first melt the sponge Ti for 2-3 minutes to absorb the oxygen in the furnace and then melt the target alloy metal raw material; after each smelting, the alloy ingot is turned over and re-melted after it is completely cooled and solidified. After turning and re-melting for more than 5 times, it is naturally solidified to obtain a high-entropy alloy master alloy ingot;

[0016] S3, Molding

[0017] The high entropy alloy master alloy ingot of S2 was placed in a copper crucible of an electric arc furnace and the vacuum in the furnace was pumped to 4×10 -3 Pa, fill with argon gas for atmosphere protection; turn on the smelting power supply, increase the smelting current to 450-600A (preferably 480-550A), and after the alloy ingot is completely melted, pour the alloy liquid into the mold to obtain a high-entropy alloy with ultra-high corrosion resistance and strong plasticity matching.

[0018] The preparation method according to claim 6, characterized in that:

[0019] The melting temperature of S2 is 2500-3000℃, preferably 2600-2800℃;

[0020] The alloy ingot is naturally cooled and solidified, and the temperature at which it is completely cooled and solidified is 20-200°C, preferably 25-100°C.

[0021] The preparation method according to claim 6, characterized in that:

[0022] In S2, the shape and size range of the high entropy alloy master alloy ingot is: button-shaped with a diameter of 10-150 mm;

[0023] In S2, the steel is turned over and remelted 5-10 times.

[0024] The preparation method according to claim 6, characterized in that:

[0025] S3 turns on the mechanical pump and molecular pump to pump the vacuum in the furnace to 4×10 -3 Below Pa.

[0026] The preparation method according to claim 6, characterized in that:

[0027] In S3, after the alloy ingot is completely melted, the alloy liquid is poured into a mold of the required size and shape, and cast in a copper mold. The copper mold is assembled according to the size requirements to obtain a high-entropy alloy with ultra-high corrosion resistance and matching strength and plasticity of the target shape;

[0028] In S3, the shape and size range of the target high entropy alloy are: rod-shaped or rectangular, wherein the rod has a diameter of 3-30 mm and a height of 10-120 mm, and the rectangular has a length of 5-20 mm, a width of 3-10 mm, and a height of 20-120 mm.

[0029] The design mechanism of the present invention is as follows:

[0030] Reasonable phase regulation and the selection and content of corrosion-resistant elements are effective ways to achieve the matching of corrosion resistance and mechanical properties of high entropy alloys. a Zr b Nb c V d High-entropy alloys are the target material, with the following three key design considerations. First, the TiZrNbV system readily forms a single-phase BCC structure, and the presence of lattice distortion imparts a certain degree of plasticity to the alloy while maintaining strength. Second, high Ti and Zr content can form insoluble oxides, while Nb and V can form high-valent oxides, reducing the defect density in the passivation film, thereby enabling the alloy to form a highly stable passivation film. Furthermore, Nb and V elements have high metal-metal bond energies, which can inhibit the growth kinetics of metastable pitting, further improving pitting performance.

[0031] The present invention uses a variety of pure metal elements to form a master alloy ingot, and then uses cooling circulating water to cool the copper mold to cast the alloy. The alloy material has a single BCC phase structure, has good strength and plasticity matching, and has a V SCE The invention has a simple preparation process and is suitable for large-scale industrial promotion and production practice.

[0032] The advantages and beneficial effects of the present invention are as follows:

[0033] 1. The high entropy alloy described in the present invention can achieve ultra-high pitting corrosion resistance while ensuring strong and ductile matching.

[0034] 2. The high entropy alloy of the present invention has a single BCC phase structure with lattice distortion, which makes the high entropy alloy of the present invention have a good strength-ductility match. At the same time, the corrosion current density of the high entropy alloy of the present invention is in the range of 0.089 to 0.409 μA / cm 2 , are less than 316L stainless steel and pure titanium, pitting potential range is 7644~9896mV SCE , passivation range 7928.8~10316.3mV SCE , which are higher than 316L stainless steel and pure titanium, proving that the high entropy alloy of the present invention has excellent corrosion resistance.

[0035] 3. The preparation method of the ultra-high corrosion-resistant TiZr-based high-entropy alloy with matched strength and plasticity described in the present invention can be achieved by simple vacuum arc melting and copper mold suction casting, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 XRD spectrum of .

[0037] Figure 2 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 EBSD phase diagram; wherein: (a) is a band comparison diagram of Example 1, (b) is an inverse pole figure of Example 1, and (c) is a phase distribution diagram of Example 1.

[0038] Figure 3 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 SEM-EDS images; wherein: (a)-(b) are low-magnification and high-magnification backscattered images of Example 1 respectively; (c)-(f) are distribution diagrams of Ti, Zr, Nb, and V elements.

[0039] Figure 4 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 TEM image; wherein: (a) is the high-resolution HAADF image of Example 1; (b) is the GPA analysis result of the HAADF image.

[0040] Figure 5 1-6 and the comparative example 1 show the tensile stress-strain curves of the high entropy alloys of the present invention.

[0041] Figure 6 Potentiodynamic polarization curves of the high entropy alloys of Examples 1-6 of the present invention and comparisons thereof with the high entropy alloy of Comparative Example 1, 316L stainless steel of Comparative Example 2, and pure titanium of Comparative Example 3.

[0042] Figure 7 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4The electrochemical impedance spectrum of the sample is shown in FIG. 1 and compared with the electrochemical impedance spectrum of the sample 1 and the electrochemical impedance spectroscopy of the sample 1 in FIG.

[0043] Figure 8 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 Electrochemical impedance spectroscopy of the long-term corrosion evolution process.

[0044] Figure 9 The high entropy alloy Ti of Example 1 of the present invention 46.1 Zr 23.1 Nb 15.4 V 15.4 The constant potential polarization curve and its comparison with the 316L stainless steel of comparative example 2 and the pure titanium of comparative example 3. DETAILED DESCRIPTION

[0045] The following description of the embodiments of the present invention is provided in more detail with reference to the accompanying drawings and examples to provide a better understanding of the present invention and its advantages in various aspects. However, the embodiments and examples described below are for illustrative purposes only and are not intended to limit the present invention.

[0046] Example 1

[0047] The embodiments of the present invention are all obtained by vacuum arc melting and copper mold suction casting. The chemical compositions of the specific embodiments are shown in Table 1.

[0048] The specific preparation process is:

[0049] The pure metal raw materials (Ti, Zr, Nb, V) with ultra-high corrosion resistance and strong plasticity matching the high entropy alloy were treated to remove the oxide scale. The specific process and conditions are as follows: the pure metal raw materials were polished with a file until the surface showed metallic luster. Then, the raw materials of each element were weighed according to the chemical composition of the required high entropy alloy (see Table 1);

[0050] The weighed raw materials are melted by arc melting method. The raw materials are placed in the melting furnace and the vacuum is pumped to 4×10 -3 Pa, high-purity argon (volume concentration 99.99%) is filled for atmosphere protection. During smelting, first smelt sponge Ti in a crucible in the smelting furnace for 2-3 minutes (here 2.5 minutes) to absorb the oxygen in the furnace, and then smelt the target alloy in another crucible in the smelting furnace. After each smelting (melting temperature 2700℃), the alloy ingot is turned over and re-smelted after it is completely cooled (20-30℃). After a total of 5 flipping and re-smelting, it is naturally solidified (20-30℃) to obtain a high-entropy alloy master alloy button ingot with a diameter of 70mm and a thickness of 27.4mm;

[0051] The master alloy ingot was placed in a copper crucible in an electric arc furnace, and the vacuum in the furnace was pumped to 4×10 -3 Pa, high-purity argon (99.99% by volume) was filled for atmosphere protection. The smelting power supply was turned on and the smelting current was gradually increased to 500 A. After the alloy ingot was completely melted, the alloy liquid was quickly poured into a mold with a length of 12 mm, a width of 5 mm, and a height of 100 mm. The casting was carried out in the copper mold and naturally cooled to room temperature for solidification to obtain the target shape of ultra-high corrosion-resistant high-entropy alloys with matching strength and ductility of Examples 1-6 and Comparative Example 1.

[0052] Comparative Example 2 is 316L stainless steel produced by Wuxi Hongxinwang Metal Products Co., Ltd.

[0053] Comparative Example 3 is TA2 pure titanium produced by Shaanxi Ruike Jinyan Metal Co., Ltd.

[0054] Table 1 Chemical composition (at.%) of high entropy alloys of Examples and Comparative Examples

[0055] Example Composition expression (at.%) Example 1 <![CDATA[Ti 46.1 Zr 23.1 Nb 15.4 V 15.4 ]]> Example 2 <![CDATA[Ti 56.4 Zr 28.2 Nb 7.7 V 7.7 ]]> Example 3 <![CDATA[Ti 61.6 Zr 30.8 Nb 3.8 V 3.8 ]]> Example 4 <![CDATA[Ti 56.4 Zr 28.2 Nb 15.4 ]]> Example 5 <![CDATA[Ti 56.4 Zr 28.2 V 15.4 ]]> Example 6 <![CDATA[Ti 54.5 Zr 27.3 Nb 18.2 ]]> Comparative Example 1 <![CDATA[Ti 40 Zr 10 Nb 14 V 36 ]]> Comparative Example 2 316L stainless steel Comparative Example 3 pure titanium

[0056] The phase analysis of the prepared alloy was carried out by X-ray diffractometer (XRD) technology. The equipment used was a D8 Advance diffractometer. During the measurement, the scanning range of 2θ was set to 20°~80° and the scanning rate was set to 4 degrees per minute. Figure 1 The XRD pattern of Example 1 is shown. It can be seen that there are only diffraction peaks of BCC structure in the XRD pattern of the high entropy alloy, indicating that the high entropy alloy has a single BCC structure. In order to analyze the microstructure of the alloy more clearly, EBSD test was performed on the high entropy alloy of Example 1, as shown in FIG. Figure 2 As shown, it can be found that the high entropy alloy of Example 1 has a polycrystalline single-phase BCC solid solution microstructure with uniform grain distribution, a size range of 20-80 μm, and an average grain size of 43.13 μm. Figure 3 The element distribution of the high entropy alloy of Example 1 detected by EDS is shown. It can be seen that the various constituent elements are not evenly distributed in the alloy. Ti and Nb elements tend to be enriched in the dendrite area, while Zr is enriched between dendrites. The V element is evenly distributed in the alloy without obvious segregation. Figure 4 The high-resolution high-angle annular dark field image and lattice distortion quantitative analysis of the high-entropy alloy of Example 1 are shown. GFA analysis of the high-resolution image shows that the high-entropy alloy has lattice distortion, and the lattice distortion rate is about 1.5%.

[0057] The mechanical properties of the high entropy alloys of Examples 1-6 and Comparative Example 1 were tested by tensile tests. The tensile specimens were dog-bone shaped specimens with a total length of 32 mm, a gauge length of 15 mm, a width of 2 mm, a thickness of 1 mm, a width of 10 mm at both ends, and a transition arc of 8 mm. The specific process was to maintain a constant strain rate of 5 × 10 -4 s -1 , a clamp-on extensometer with a gauge length of 12.5 mm was used throughout the process to collect mechanical data such as elongation (Reference: Zeng Shuai, Research on Composition, Microstructure and Mechanical Properties of Ti-Zr-Nb-V-Al High Entropy Alloy, 2024 Doctoral Dissertation, P33.). Figure 5 The curves of the high entropy alloys of Examples 1 to 6 of the present invention and Comparative Example 1 after tensile testing at room temperature are shown, and the corresponding mechanical performance parameters are shown in Table 2. It can be seen that the high entropy alloys of Examples 1 to 6 all exhibit high yield strength (388-871 MPa) and tensile strength (651-886 MPa) while having an elongation of more than 10%, indicating that the high entropy alloy system has a good match between strength and plasticity. While the high entropy alloy of Comparative Example 1 has a higher strength, its elongation is only 5.2%, indicating a poor match between strength and plasticity.

[0058] Table 2 Room temperature mechanical properties of high entropy alloys according to the present invention

[0059] Example Yield strength (MPa) Tensile strength (MPa) Elongation after break (%) Example 1 871 886 19.30 Example 2 388 801 19.00 Example 3 488 768 16.75 Example 4 729 737 17.70 Example 5 827 856 11.95 Example 6 635 651 12.75 Comparative Example 1 712 727 5.28

[0060] The pitting corrosion resistance of the Examples and Comparative Examples was tested using potentiodynamic polarization on a Gamry Instruments Interface 600+ electrochemical workstation. The electrolyte was a 3.5 wt.% NaCl aqueous solution. The Examples and Comparative Examples served as working electrodes, a saturated calomel electrode served as the reference electrode, and a platinum sheet served as the auxiliary electrode. Before testing, the alloy electrodes were subjected to potentiodynamic polarization for 300 seconds at a potential of -1 V relative to the reference electrode to remove the natural oxide film formed on the test surface in air. The electrodes were then immersed at open circuit potential for at least 1800 seconds to allow them to reach a relatively stable state. The potentiodynamic polarization test was performed at a potential scan rate of 20 mV / min, starting at 400 mV below the open circuit potential and continuing in a positive direction until the current suddenly increased (Reference: Wang Debin, Corrosion Mechanism of B-Containing Stainless Steel and Fe-Based Amorphous Alloy in Spent Fuel Storage Environments, 2024 PhD Dissertation, p. 36). Figure 6The potentiodynamic polarization behavior of the high entropy alloys of Examples 1 to 6 of the present invention, the high entropy alloy of Comparative Example 1, the 316L stainless steel of Comparative Example 2, and the pure titanium of Comparative Example 3 in a 3.5 wt.% NaCl aqueous solution is shown. The corresponding corrosion parameters obtained from the curves are listed in Table 3, where the corrosion current density of the high entropy alloys of Examples 1 to 6 of the present invention ranges from 0.089 to 0.409 μA / cm 2 , which are all lower than those of the high entropy alloy, 316L stainless steel and pure titanium in comparative example 1, with self-corrosion potentials of -452.8 to -284.8 mV SCE , pitting potential range 7644~9896mV SCE , passivation range 7928.8~10316.3mV SCE , which are higher than those of the high entropy alloy, 316L stainless steel and pure titanium in comparative example 1, proving that the high entropy alloy of the present invention has excellent corrosion resistance. The curves show that all the high entropy alloys of the examples directly enter the passivation zone without going through the activation-passivation transition state, which indicates the ability to spontaneously passivate at their corresponding corrosion potentials. In addition, the passivation curves of all the high entropy alloys of the examples can be distinguished into two different regions: at 6V SCE In the area below, the curve is very smooth and there is no obvious current transient peak, indicating that the high entropy alloy substrate is protected by a stable passivation film. The difference is that when the potential exceeds 6V SCE When the potential is high, a large number of current transient peaks appear, especially at higher potentials, indicating that the stability of the passivation film decreases at high potentials. At this time, the high corrosion resistance of the high entropy alloy is controlled by the growth kinetics of metastable pitting.

[0061] Table 3 Comparison of electrochemical parameters obtained by potentiodynamic polarization in 3.5 wt.% NaCl solution for high entropy alloys of Examples 1-6 of the present invention, high entropy alloy of Comparative Example 1, 316L stainless steel, and pure titanium

[0062]

[0063] The corrosion performance of the examples and comparative examples was further compared using electrochemical impedance spectroscopy (EIS) using a Gamry Instruments Interface 600+ electrochemical workstation. The electrolyte was a 3.5 wt.% NaCl aqueous solution. The examples and comparative examples served as working electrodes, a saturated calomel electrode served as the reference electrode, and a platinum sheet served as the auxiliary electrode. The tests were conducted at open circuit potential (OCP) with a potential amplitude of 10 mV and a frequency range of 10,000 to 0.01 Hz. (Reference: Wang Debin, Corrosion Mechanism of B-Containing Stainless Steel and Fe-Based Amorphous Alloy in Spent Fuel Storage Environments, 2024 PhD Dissertation, p. 37.) Figure 7Electrochemical impedance spectroscopy (EIS) measurements of Example 1, 316L stainless steel, and pure titanium. All impedance spectra show radial arcs, indicating similar passivation behavior. Notably, the radius of the high-entropy alloy from Example 1 is significantly larger than that of 316L stainless steel and pure titanium, indicating its enhanced corrosion resistance. Figure 8 The long-term corrosion evolution process of the electrochemical impedance spectroscopy of the high-entropy alloy of Example 1 is shown. It can be seen that after immersion for 8000 hours, the high-entropy alloy still maintains excellent corrosion resistance.

[0064] The pitting corrosion resistance of the examples and comparative examples was tested by potentiostatic polarization. The instrument was an Interface 600+ electrochemical workstation produced by Gamry. The electrolyte was a 3.5 wt.% NaCl aqueous solution. The examples and comparative examples were used as working electrodes, a saturated calomel electrode was used as the reference electrode, and a platinum sheet was used as the auxiliary electrode. The specific process was as follows: before the potentiostatic polarization test, the electrodes were first charged at -1V. SCE The natural oxide film on the alloy surface was removed by constant potential polarization for 300 s. Then, the corresponding potential was selected for constant potential polarization. The data recording frequency was 0.5 s per point, and the constant potential polarization time was 3600 s (Reference: Wang Debin, Study on the Corrosion Mechanism of B-Containing Stainless Steel and Fe-Based Amorphous Alloy in Spent Fuel Storage Environment, 2024 Doctoral Dissertation, P36.). Figure 9 The constant potential polarization curves of Example 1 of the present invention and 316L stainless steel and pure titanium show that the current density of the high entropy alloy and pure titanium decreases over time, which can be attributed to the growth of the passivation film on their surfaces. It is worth noting that the current density of the high entropy alloy is significantly lower than that of pure titanium, which indicates that a more protective passivation film is formed on the surface of the high entropy alloy. In contrast, the current density of 316L stainless steel continues to rise over time, which indicates that this alloy cannot form a stable passivation film at high potentials.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A TiZr-based high-entropy alloy with ultra-high corrosion resistance and matching strength and plasticity, characterized by: The chemical expression of the high entropy alloy is Ti in atomic percentage. a Zr b Nb c V d , where 25≤a≤65, 12≤b≤35, 0≤c≤35, 0≤d≤35, where a+b+c+d=100, and c and d cannot be 0 at the same time, and their sum 3≤c+d≤50.

2. The high entropy alloy according to claim 1, wherein: In the chemical expression of the high entropy alloy, 30≤a≤62, 15≤b≤31, 3≤c≤31, 3≤d≤31, and a+b+c+d=100.

3. The high entropy alloy according to claim 1 or 2, characterized in that: The phase structure of the high entropy alloy is a single BCC phase.

4. The high entropy alloy according to claim 1, 2 or 3, wherein: The high entropy alloy has a yield strength of 300-900 MPa, a tensile strength of 600-900 MPa, and an elongation after fracture greater than 10%.

5. The high entropy alloy according to claim 1, 2 or 3, wherein: The self-corrosion current density of the high entropy alloy is less than 0.5 μA / cm 2 , pitting potential range is higher than 7000mV SCE , passivation range is greater than 7500mV SCE .

6. A preparation method according to any one of claims 1 to 5, characterized in that: The ultra-high corrosion-resistant TiZr-based high-entropy alloy with matched strength and ductility is synthesized by arc melting. The alloy ingot melting process needs to be carried out in an argon protection environment. The specific steps are as follows: S1. Ingredients Descaling the pure metal raw material of the metal required for the high entropy alloy with ultra-high corrosion resistance and strong plasticity, and then weighing the raw materials of each element according to the chemical composition of the high entropy alloy; S2. Melting The weighed raw materials of S1 are melted by arc melting method. The raw materials are placed in the melting furnace and the vacuum is pumped to 4×10 -3 Pa below, filled with argon for atmosphere protection; during smelting, first melt the sponge Ti for 2-3 minutes to absorb the oxygen in the furnace and then melt the target alloy metal raw material; after each smelting, the alloy ingot is turned over and re-melted after it is completely cooled and solidified. After turning and re-melting for more than 5 times, it is naturally solidified to obtain a high-entropy alloy master alloy ingot; S3, Molding The high entropy alloy master alloy ingot of S2 was placed in a copper crucible of an electric arc furnace and the vacuum in the furnace was pumped to 4×10 -3 Pa below, fill with argon gas for atmosphere protection; Turn on the smelting power supply and increase the smelting current to 450-600A (preferably 480-550A). After the alloy ingot is completely melted, pour the alloy liquid into the mold to obtain a high-entropy alloy with ultra-high corrosion resistance and matching strength and plasticity.

7. The preparation method according to claim 6, characterized in that: The melting temperature of S2 is 2500-3000℃, preferably 2600-2800℃; The alloy ingot is naturally cooled and solidified, and the temperature at which it is completely cooled and solidified is 20-200°C, preferably 25-100°C.

8. The preparation method according to claim 6, characterized in that: In S2, the shape and size range of the high entropy alloy master alloy ingot is: button-shaped (or cylindrical), with a diameter of 10-150 mm and a thickness or height of 2-50 mm; In S2, the steel is turned over and remelted 5-10 times.

9. The preparation method according to claim 6, characterized in that: S3 turns on the mechanical pump and molecular pump to pump the vacuum in the furnace to 4×10 -3 Below Pa.

10. The preparation method according to claim 6, characterized in that: In S3, after the alloy ingot is completely melted, the alloy liquid is poured into a mold of the required size and shape, and cast in a copper mold. The copper mold is assembled according to the size requirements to obtain a high-entropy alloy with ultra-high corrosion resistance and matching strength and plasticity of the target shape; In S3, the shape and size range of the target high entropy alloy are: rod-shaped or rectangular, wherein the rod has a diameter of 3-30 mm and a height of 10-120 mm, and the rectangular has a length of 5-20 mm, a width of 3-10 mm, and a height of 20-120 mm.

Images