Titanium-tantalum-chromium series high-entropy alloy material and preparation method thereof

Abstract

The invention discloses a titanium-tantalum-chromium series high-entropy alloy material and a preparation method thereof. By introducing the Al element with the specific content, a Cr2Al strengthening phase is generated, more importantly, strong lattice distortion is induced, and rapid diffusion of Al and Cr atoms to the surface is greatly promoted, so that a layer of continuous, compact and stable composite oxide film mainly comprising Al2O3 and Cr2O3 can be formed at the initial stage of high-temperature oxidation, and inward diffusion of oxygen is effectively blocked. By adjusting the content of the Al element, the alloy is statically oxidized for 48 hours at the temperature of 1000 DEG C, the oxidation rate is as low as 3.671 g / m.h, the high-temperature service life of the TiTaCr-series high-entropy alloy is remarkably prolonged, and the reliability of the TiTaCr-series high-entropy alloy is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy alloy preparation technology, specifically relating to a titanium-tantalum-chromium high-entropy alloy material and its preparation method. Background Technology

[0002] Currently, widely used traditional high-temperature alloys such as Fe, Co, and Ni-based alloys can no longer meet the material requirements of the aerospace field. With the continuous development of advanced aero-engines and gas turbines, advanced high-temperature structural materials have become a core element in improving engine performance, extending their service life, and reducing energy consumption and costs. Due to the harsh service conditions of high-temperature hot-end components, which are subjected to high-temperature oxidation corrosion, temperature shock, and strong airflow erosion, there is an urgent need to prepare new high-temperature alloys that combine high-temperature strength and high-temperature oxidation resistance.

[0003] High-entropy refractory alloys (RHEAs) are promising new high-temperature structural materials; however, their insufficient high-temperature oxidation resistance has become a key bottleneck restricting their application. This invention starts with the material's structural design, fundamentally improving its oxidation resistance by controlling microscopic defects. This invention induces lattice distortion by introducing relevant antioxidant elements, utilizing the rapid diffusion effect generated by the distortion to achieve efficient transport of antioxidant elements and rapid self-generation of a protective film, providing a novel solution to the high-temperature oxidation failure problem of RHEAs. This offers a new approach to the design and development of heat-resistant alloy materials, and is expected to overcome the structural and performance bottlenecks of traditional alloys. Summary of the Invention

[0004] To address the aforementioned technical problems, the first objective of this invention is to provide a method for preparing titanium-tantalum-chromium-based high-entropy alloy materials. The preparation method of this invention is simple, controllable, and suitable for industrial production.

[0005] The second objective of this invention is to provide a titanium-tantalum-chromium high-entropy alloy material prepared by the above-described preparation method.

[0006] To achieve the above objectives, the present invention employs the following preparation method:

[0007] This invention discloses a method for preparing a titanium-tantalum-chromium high-entropy alloy material, wherein each metal raw material is prepared according to a design ratio and repeatedly smelted under a protective atmosphere to obtain the titanium-tantalum-chromium high-entropy alloy material.

[0008] The current intensity for the first melting is 40-60A. Then, the current intensity is increased by 5-15A for the second to N-1 meltings. Finally, for the Nth melting, the current intensity is reduced by 20-25A compared to the N-1th melting.

[0009] The smelting was carried out under electromagnetic stirring;

[0010] The titanium-tantalum-chromium high-entropy alloy material has the following composition by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, Al 5%-25%.

[0011] The titanium-tantalum-chromium high-entropy alloy material provided by this invention, by introducing a specific amount of Al element, not only generates a Cr2Al strengthening phase, but more importantly, induces strong lattice distortion through control of the preparation process and composition. The preparation method of this invention employs a stepped heating melting method to allow Al element to fully diffuse and dissolve, increasing its influence on lattice distortion, while simultaneously promoting the uniform precipitation of the nanoscale Cr2Al phase. Electromagnetic stirring further promotes the uniform distribution of solute elements, ensuring the uniformity of the lattice distortion effect and greatly promoting the rapid diffusion of Al and Cr atoms to the surface. Furthermore, the addition of Nb... 5+ Ionic radius and Ti 4+ Unlike other materials, it can dissolve into the TiO2 lattice, effectively "blocking" vacancies and channels in the lattice, significantly reducing the diffusion rate of oxygen ions and titanium ions in TiO2, thus making the oxide layer more compact. At the same time, it can promote the formation of Al2O3 film, thereby rapidly forming a continuous, dense, and stable composite oxide film mainly composed of Al2O3 and Cr2O3 in the early stage of high-temperature oxidation, effectively blocking the inward diffusion of oxygen; thus greatly improving the high-temperature oxidation resistance.

[0012] Experiments have shown that when using the stepped heating melting method of this invention, the first to N-1 steps all use a gradient increase in current intensity, i.e., heating, while the last step requires cooling, i.e., reducing the current, to melt. This not only reduces the fluctuation of the molten pool during melting, but also promotes uniform composition, reduces element segregation, and avoids the overheating and volatilization of metal elements, ensuring the stability of the alloy composition and structure.

[0013] In a preferred embodiment, the metal raw material is first pretreated. The pretreatment process involves sequentially polishing with #80, #320, #400, #600, #800 and #1000 sandpaper, followed by mechanical polishing with diamond polishing agent until the surface is free of scratches. Then, the metal raw material is ultrasonically cleaned for 5-10 minutes using anhydrous ethanol as the cleaning solvent.

[0014] The preferred method involves mixing the various metal raw materials according to the design proportions, placing them in a water-cooled copper crucible, and then placing it in the furnace cavity of a non-consumable vacuum arc melting furnace. The furnace is first evacuated to a vacuum level of 2×10⁻⁶. 2 Below Pa, then fill with argon gas to 5-10 Pa.

[0015] In a preferred embodiment, the metal raw material is pure Ti, pure Ta, pure Cr, pure Nb, or pure Al with a purity ≥ 99.9 wt%.

[0016] Further optimization involves first placing pure Ta and pure Nb at the bottom of the crucible, then placing pure Cr and pure Ti above them as a transition layer, and finally adding pure Al. This prevents Al from melting and volatilizing prematurely during the smelting process.

[0017] In a preferred embodiment, the number of melting cycles N is 4 to 6.

[0018] The preferred method is to melt for 10-60 seconds at any one time, and then hold the melt for 5-10 minutes after the last melting is completed.

[0019] In actual operation, after the previous melting is completed and before the next melting process, the melted button sample must be flipped. After all the melting processes are completed and cooled, the oxide layer on the surface of the button sample is cleaned and removed. Then the above-mentioned electric arc melting steps are performed again. Finally, after cooling, TiTaCrNbAl high-entropy alloy material can be obtained.

[0020] In a preferred embodiment, the electromagnetic stirring process involves alternately turning the electromagnetic field on and off, with each on-time lasting 8-12 seconds, an electromagnetic frequency of 45-60Hz, and a current intensity of 60-100A. Experiments have shown that this intermittent strong stirring mode effectively breaks dendrite growth, promotes the uniform distribution of solute elements (especially Al), avoids macroscopic segregation, and thus ensures the uniformity and consistency of lattice distortion effects.

[0021] In a preferred embodiment, the titanium-tantalum-chromium high-entropy alloy material has the following composition by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 9.5%-21%.

[0022] In a further preferred embodiment, the titanium-tantalum-chromium high-entropy alloy material has the following composition by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 18%-21%.

[0023] The present invention also provides a titanium-tantalum-chromium high-entropy alloy material prepared by the above preparation method, wherein the titanium-tantalum-chromium high-entropy alloy material has a dendritic structure and secondary dendrites, the secondary dendrites containing Cr2Al phase.

[0024] Principles and advantages:

[0025] The atomic radius of Al is much smaller than that of the main matrix elements Ta, Nb, and Ti. When Al atoms dissolve into the BCC main phase lattice, they replace larger atomic positions, causing strong local compressive strain in the surrounding lattice and introducing severe lattice distortion throughout the alloy. This lattice distortion increases the defect density, such as dislocations and grain boundaries, in titanium-tantalum-chromium high-entropy alloys. The presence of these defects provides channels for the rapid diffusion of antioxidant elements such as Al and Cr, promoting the formation of their antioxidant oxides. During high-temperature oxidation, sufficient Al and Cr atoms diffuse rapidly to the alloy surface through these rapid diffusion channels, preferentially oxidizing to form a continuous, dense, and well-adhered Al(TaO4) or (AlTiTa)2O layer. 12 A mixed oxide film with CrTaO4 is formed. This protective film effectively blocks the intrusion of oxygen, thereby significantly reducing the oxidation rate and achieving a qualitative leap in the body's antioxidant capacity.

[0026] This invention uses TiTaCrNb high-entropy alloy as the matrix. By introducing a specific amount of Al element, not only is a Cr2Al strengthening phase generated, but more importantly, strong lattice distortion is induced through control of the preparation process and composition. The preparation method of this invention adopts a stepped heating melting method to allow Al element to fully diffuse and dissolve, increasing its influence on lattice distortion. At the same time, it promotes the uniform precipitation of nanoscale Cr2Al phase. Electromagnetic stirring promotes the uniform distribution of solute elements, ensuring the uniformity of the lattice distortion effect. This greatly promotes the rapid diffusion of Al and Cr atoms to the surface, thereby forming a continuous, dense, and stable composite oxide film mainly composed of Al2O3 and Cr2O3 in the early stage of high-temperature oxidation, effectively blocking oxygen diffusion inward; thus significantly improving high-temperature oxidation resistance.

[0027] Compared with the prior art, the present invention has at least the following advantages:

[0028] 1. This invention breaks through the traditional approach of simply relying on the content of antioxidant elements. By actively introducing a new variable, lattice distortion, and utilizing the rapid diffusion channels generated by the distortion, it achieves efficient utilization of antioxidant elements (Al, Cr) and rapid self-generation of the protective film, fundamentally solving the problem of high-temperature oxidation from a kinetic perspective.

[0029] 2. Through the synergistic effect of Al element doping and lattice distortion, this invention successfully improves the oxidation resistance of TiTaCrNb high-entropy alloy, significantly extending the service life of the material under high-temperature extreme environments.

[0030] 2. The stepped melting and intermittent electromagnetic stirring process provided by this invention can effectively control the distribution of Al elements and the degree of lattice distortion. The process parameters are clear and the reproducibility is good, laying a solid foundation for the industrial preparation of high-performance oxidation-resistant refractory high-entropy alloys. Attached Figure Description

[0031] Figure 1 The X-ray diffraction spectra of the as-cast TiTaCrNbAl high-entropy alloy materials prepared in Examples 1, 2 and 3 are shown.

[0032] Figure 2 X-ray diffraction patterns of the as-cast TiTaCrZrV high-entropy alloy materials prepared for Comparative Examples 1, 2 and 3.

[0033] Figure 3 The images show SEM images and EDS surface scan results of the as-cast TiTaCrNbAl high-entropy alloy materials prepared in Examples 1, 2, and 3; wherein: (a) is the TiTaCrNb alloy prepared in Example 1; (b) is the TiTaCrNbAl alloy prepared in Example 2. 10 Alloy; (c) is TiTaCrNbAl prepared in Example 3 20 alloy.

[0034] Figure 4 The as-cast TiTaCrNbAl prepared in Example 3 20 Magnified SEM-EDS image of the dendritic region of a high-entropy alloy material.

[0035] Figure 5 SEM images and EDS surface scan results of the as-cast TiTaCrxZrV high-entropy alloy materials prepared in Comparative Examples 1, 2, and 3 are shown below; where: (a) is the TiTaZrV alloy prepared in Comparative Example 1; (b) is the TiTaCrxZrV alloy prepared in Comparative Example 2. 10 ZrV alloy; (c) TiTaCr prepared in Comparative Example 3 20 ZrV alloy.

[0036] Figure 6 The X-ray diffraction patterns of the TiTaCrNbAl high-entropy alloy materials prepared in Examples 1, 2 and 3 after oxidation at 1000℃ for 48 hours are shown.

[0037] Figure 7 The continuous weight gain curves of the TiTaCrNbAl high-entropy alloy materials prepared in Examples 1, 2 and 3 after oxidation at 1000℃ for 48 h are shown. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] This embodiment provides a TiTaCrNb high-entropy alloy material, the preparation process of which includes the following steps:

[0041] (1) The mass of a single button ingot is 100g. According to the mass ratio of Ti:Ta:Cr:Nb=12.8%:48.4%:13.9%:24.9%, the required masses are: Ti-12.8g; Ta-48.4g; Cr-13.9g; Nb-24.9g.

[0042] Surface pretreatment of elemental metals: Impurities and oxides on the surface of elemental metals Ta, Ti, Cr, and Nb are removed by manual grinding. They are then polished sequentially with #80, #320, #400, #600, #800, and #1000 sandpaper, followed by mechanical polishing with diamond polishing compound until the surface is free of scratches. Finally, the elemental metals Ta, Ti, Cr, and Nb are ultrasonically cleaned for 5 minutes using anhydrous ethanol as the cleaning solvent and then dried for later use.

[0043] The treated elemental metals Ta, Ti, Cr, and Nb were placed in a water-cooled copper crucible and then placed in a non-consumable vacuum arc melting furnace, and the furnace was evacuated to a vacuum level of 2 × 10⁻⁶. 2 After Pa, backfill with inert argon gas to 5 Pa;

[0044] (2) Arc melting of elemental metals Ta, Ti, Cr, and Nb was carried out under argon protection. The first melting used a low current (60A) to initially alloy the metals. For the subsequent four meltings, the current was gradually increased to 80A, 90A, and 100A, with a melting time of 1 minute. The final melting was reduced to 80A and held at that temperature for 8 minutes. Simultaneously, intermittent strong electromagnetic stirring was used to increase the uniformity of the alloy mixture. The electromagnetic field was alternately turned on and off at a frequency of 50Hz, with each onset lasting 10 seconds and a current intensity of 80A. After multiple arc meltings, the resulting ingots were cooled and the oxide layer on the surface of the ingots was further removed using an angle grinder. After cooling, a cast TiTaCrNb high-entropy alloy, labeled Al0, was obtained.

[0045] Example 2

[0046] A TiTaCrNbAl 10 The mass of a single button ingot made of high-entropy alloy material is 100g. Based on the mass ratio of Ti:Ta:Cr:Nb:Al = 12.4%:46.9%:13.5%:24.1%:3.1%, the required masses are: Ti - 12.4g; Ta - 46.9g; Cr - 13.5g; Nb - 24.1g; Al - 3.1g.

[0047] Surface pretreatment of elemental metals: Impurities and oxides on the surface of elemental metals Ta, Ti, Cr, Nb, and Al are removed by manual grinding. They are then polished sequentially with #80, #320, #400, #600, #800, and #1000 sandpaper, followed by mechanical polishing with diamond polishing compound until the surface is free of scratches. Finally, the elemental metals Ta, Ti, Cr, Nb, and Al are ultrasonically cleaned for 5 minutes using anhydrous ethanol as the cleaning solvent and then dried for later use.

[0048] The treated elemental metals Ta, Ti, Cr, Nb, and Al were placed in a water-cooled copper crucible. Pure Ta and pure Nb were first placed at the bottom of the crucible, followed by pure Cr and pure Ti as a transition layer above the pure Ta and pure Nb. Finally, pure Al was added, and the crucible was placed in a non-consumable vacuum arc melting furnace, which was then evacuated to a vacuum level of 2 × 10⁻⁶. 2 After Pa, backfill with inert argon gas to 5 Pa;

[0049] Arc melting of elemental metals Ta, Ti, Cr, Nb, and Al was performed under argon protection. The first melting used a low current (60A) to initially alloy the metals. In the subsequent four meltings, the current was gradually increased to 80A, 90A, and 100A, with a melting time of 1 minute. The final melting was reduced to 80A and held at that temperature for 8 minutes. Simultaneously, intermittent strong electromagnetic stirring was used to increase the uniformity of alloy mixing. The electromagnetic field was alternately turned on and off at a frequency of 50Hz, with each onset lasting 10 seconds and a current intensity of 80A. After multiple arc meltings, the resulting ingots were cooled and the oxide layer on the surface was further removed using an angle grinder. After cooling, the as-cast TiTaCrNbAl was obtained. 10 High-entropy alloy, designated Al10.

[0050] Example 3

[0051] A TiTaCrNbAl 20The high-entropy alloy material was prepared using the same process as in Example 2, except that Al was added and the proportions of the alloy elements were different. A single button ingot weighed 100g. Based on the mass ratio of Ti:Ta:Cr:Nb:Al = 12.0%:45.1%:13.0%:23.2%:6.7%, the required masses were: Ti - 12.0g; Ta - 45.1g; Cr - 13.0g; Nb - 23.2g; Al - 6.7g. The final product was a cast TiTaCrNbAl alloy. 20 High-entropy alloy, designated Al20.

[0052] Comparative Example 1

[0053] Other conditions are the same as in Example 2, except that this comparative example provides a TiTaZrV high-entropy alloy material. The mass of a single button ingot is 100g. According to the mass ratio of Ti:Ta:Zr:V = 12.9%:48.8%:24.5%:13.8%, the required masses are: Ti - 12.9g; Ta - 48.8g; Zr - 24.5g; V - 13.8g. Finally, a cast TiTaZrV high-entropy alloy is obtained, labeled as Cr0.

[0054] Comparative Example 2

[0055] Other conditions are the same as in Example 2, except that this comparative example provides a TiTaCr 10 For ZrV high-entropy alloy material, the mass of a single button ingot is 100g. Based on the mass ratio of Ti:Ta:Cr:Zr:V = 12.3%:46.2%:5.3%:23.2%:13.0%, the required masses are: Ti - 12.3g; Ta - 46.2g; Cr - 5.3g; Zr - 23.2g; V - 13.0g. The final product is a cast TiTaCr alloy. 10 ZrV high-entropy alloy, designated Cr10.

[0056] Comparative Example 3

[0057] Other conditions are the same as in Example 2, except that this comparative example provides a TiTaCr 20 For ZrV high-entropy alloy material, with a mass ratio of Ti:Ta:Cr:Zr:V = 11.4%:42.8%:12.3%:21.5%:12.1%, the required masses are: Ti - 11.4g; Ta - 42.8g; Cr - 12.3g; Zr - 21.5g; V - 12.1g. The final prepared as-cast TiTaCr alloy is obtained. 20 ZrV high-entropy alloy, designated as Cr20.

[0058] Comparative Example 4

[0059] Other conditions were the same as in Example 2, except that constant current melting was used. The electric arc melting was maintained at 70A for 1 minute throughout any single melting process. The thermal field provided by constant current melting was too stable, which was not conducive to breaking and severing dendrites. This resulted in coarse dendrites in the melted sample, reduced grain boundary diffusion channels, and hindered the diffusion of antioxidant elements. It also failed to promote the generation of lattice distortion. In addition, the stable current would cause the volatilization of elements to be aggravated in high-entropy alloy systems with large differences in melting points, resulting in a large deviation between the actual composition of the alloy and the designed composition.

[0060] Comparative Example 5

[0061] Other conditions are the same as in Example 2, except that electromagnetic stirring is turned on and the stirring mode is continuous stirring. The continuous and stable unidirectional eddy current will fix the flow pattern inside the molten pool. High-density elements are continuously inclined to the outside of the molten pool under the action of centrifugal force, while low-density elements are enriched in the center or upper part of the molten pool, which will aggravate macroscopic segregation at different positions of the ingot and is not conducive to the uniform distribution of antioxidant elements.

[0062] Performance testing:

[0063] Oxidation test: The alloys smelted in Examples 1, 2, 3, and Comparative Examples 1, 2, and 3 were cut into 10×10×10mm pieces using wire EDM. 2 The sample was prepared as a cube. It was then polished with SiC sandpaper in the order of #80, #320, #400, #600, #800, and #1000 until a mirror-like finish appeared on the surface. Next, it was polished with diamond polishing compound until no obvious scratches were visible under an optical microscope. The sample was ultrasonically cleaned in anhydrous ethanol for 5 minutes, followed by ultrasonic cleaning with water for another 5 minutes. It was then dried in a drying oven at 70°C for 2 hours. The net weight of the dried sample was measured using an electronic balance with an accuracy of 0.0001 g. The sample was then placed in an Al2O3 crucible, and the total weight of the sample and crucible was measured. The crucible was placed in a tube furnace at 1000°C for oxidation testing. The sample was removed every two hours, cooled to room temperature, and then weighed.

[0064] After sample polishing, X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterization can be performed. During XRD testing... With the angle set to 10-90° and the scanning speed at 5° / min, the X-ray diffraction (XRD) pattern obtained after the test is completed is as follows: Figure 1 , Figure 2 As shown, Figure 1 In this diagram, BCC has a body-centered cubic structure. The X-ray energy dispersive spectroscopy (EDS) surface scan results of the backscattered electron (BSE) image are shown below. Figure 3 , 5 As shown, Figure 3In the image, (a) shows the as-cast TiTaCrNb alloy prepared in Example 1; (b) shows the TiTaCrNbAl alloy prepared in Example 2. 10 (c) TiTaCrNbAl prepared in Example 3, in the as-cast state. 20 Alloy as-cast state; Figure 5 In the image, (a) shows the as-cast TiTaZrV alloy prepared in Comparative Example 1; (b) shows the TiTaCr alloy prepared in Comparative Example 2. 10 (c) ZrV alloy in as-cast state; (c) TiTaCr prepared in Comparative Example 3 20 ZrV alloy in as-cast state.

[0065] Depend on Figure 1 It can be seen that the TiTaCrNb alloy prepared in Example 1 and the TiTaCrNbAl alloy prepared in Example 2 are similar. 10 The alloy is mainly composed of the BCC phase. With the increase of Al content, the TiTaCrNbAl alloy prepared in Example 3... 20 The XRD diffraction peaks of the alloy showed significant broadening and shift towards lower angles. Peak broadening indicates increased lattice stress and defect density; the peak shift directly confirms that the solid solution of Al atoms led to a decrease in the BCC lattice constant. These two factors together constitute experimental evidence of severe lattice distortion. This distortion provides a rapid diffusion path for Cr and Al atoms, promoting the formation of Cr and Al oxide films and enhancing the oxidation resistance of the TiTaCr system. Example 3: TiTaCrNbAl 20 The alloy also incorporates a Cr2Al phase in addition to the BCC phase. Furthermore, the addition of Al causes the diffraction peaks to shift to the left overall. This is because Al has an atomic radius of only 118 pm, which is relatively small compared to other elements, and the addition of Al causes lattice distortion.

[0066] Depend on Figure 3 It can be seen that the as-cast TiTaCrNbAl alloy exhibits a typical dendritic morphology, with dendrites rich in Cr and Ti, interdendritic regions rich in Al and Ta, and Nb basically uniformly distributed. With increasing Al content, secondary dendrites appear in the dendritic regions. 20 This is particularly evident. A magnified image of the dendritic region is shown below. Figure 4 As shown, the secondary dendrite region is mainly enriched with Cr. Based on the elemental distribution and XRD results, it is judged that it may be Cr2Al.

[0067] Depend on Figure 5It can be seen that the as-cast TiTaCrZrV alloy also exhibits a typical dendritic morphology, in which the dendrites are rich in Zr and Ti, and the interdendritic regions are rich in V, Ta, and Cr, which are basically evenly distributed. With the increase of Cr doping, on the one hand, the rough convex particles are reduced, and when the Cr content is increased to 20 wt.%, the convex particles completely disappear; on the other hand, Cr doping is conducive to the integration of rough convex particles with the matrix.

[0068] The X-ray diffraction patterns of the high-entropy alloy materials prepared in Examples 1, 2, and 3 after oxidation at 1000℃ for 48 hours are shown below. Figure 6 As shown, all three alloys produced six oxidation products: Ta₂O₅, TaO₂, TiO₂, CrNbO₄, CrTaO₄, and TiTaO₄. The TiTaCrNbAl alloy, doped with Al, also produced oxidation products. 10 Alloys and TiTaCrNbAl 20 The alloy also produced Al(TaO4) and (AlTiTa)2O. 12 Two aluminum oxides enhance the alloy's oxidation resistance.

[0069] The continuous weight gain curves of the high-entropy alloy materials prepared in Examples 1, 2, and 3 after oxidation at 1000℃ for 48 hours are shown below. Figure 7 As shown. The TiTaCrNb alloy prepared in Example 1, after 48 hours of continuous oxidation, showed an oxidation rate of 29.047 g / m. 2 ·h, TiTaCrNbAl prepared in Example 2 10 The alloy, after 48 hours of continuous oxidation, exhibited an oxidation rate of 15.138 g / m. 2 ·h. Example 3: TiTaCrNbAl 20 After 48 hours of continuous oxidation, the oxidation rate of the alloy was only 3.671 g / m. 2 Compared to Examples 1 and 2, the oxidation rate in Example 3 decreased by 25.375 g / m³. 2 ·h and 11.466g / m 2 ·h.

[0070] The TiTaZrV high-entropy alloy material prepared in Comparative Example 1 showed an oxidation rate of 160.259 g / m after 12 hours of continuous oxidation. 2 ·h, TiTaCr prepared in Comparative Example 2 10 The ZrV alloy exhibited an oxidation rate of 103.458 g / m after 12 hours of continuous oxidation. 2 ·h, TiTaCr prepared in Comparative Example 3 20 The ZrV alloy exhibited an oxidation rate of 51.549 g / m after 12 hours of continuous oxidation. 2·h.

[0071] In addition, TiTaCrNbAl was prepared by constant current melting in Comparative Example 4. 10 The alloy, after 48 hours of continuous oxidation, exhibited an oxidation rate of 135.452 g / m. 2 ·h, Comparative Example 5: TiTaCrNbAl prepared by continuous stirring 10 The alloy, after 48 hours of continuous oxidation, exhibited an oxidation rate of 150.334 g / m. 2 ·h, all are higher than in Example 2.

[0072] It is evident that the appropriate synergistic addition of Nb and Al elements in the process of this invention can reduce oxidation weight gain, greatly improve the high-temperature oxidation resistance of TiTaCr high-entropy alloy, and extend the high-temperature service life of the alloy.

[0073] 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 within the protection scope of the present invention.

Claims

1. A method for preparing a titanium-tantalum-chromium high-entropy alloy material, characterized in that: According to the design ratio, each metal raw material is prepared and repeatedly smelted under a protective atmosphere to obtain a titanium-tantalum-chromium high-entropy alloy material. The current intensity for the first melting is 40-60A. Then, the current intensity is increased by 5-15A for the second to N-1 meltings. Finally, for the Nth melting, the current intensity is reduced by 20-25A compared to the N-1th melting. The smelting was carried out under electromagnetic stirring; The titanium-tantalum-chromium high-entropy alloy material has the following composition by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, Al 5%-25%.

2. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The metal raw material is first pretreated by grinding with #80, #320, #400, #600, #800 and #1000 sandpaper in sequence, followed by mechanical polishing with diamond polishing agent until the surface is free of scratches. Then, the metal raw material is ultrasonically cleaned for 5-10 minutes using anhydrous ethanol as the cleaning solvent.

3. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: Prepare the various metal raw materials according to the design ratio, place them in a water-cooled copper crucible, and then place it in the furnace cavity of a non-consumable vacuum arc melting furnace. First, evacuate the furnace to 2×10⁻⁶ ℃. 2 Below Pa, then fill with argon gas to 5-10 Pa.

4. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The metal raw materials are pure Ti, pure Ta, pure Cr, pure Nb, and pure Al with a purity of ≥99.9wt%.

5. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 4, characterized in that: First, place pure Ta and pure Nb at the bottom of the crucible, then place pure Cr and pure Ti on top of pure Ta and pure Nb as a transition layer, and finally add pure Al.

6. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The number of smelting cycles, N, is 4 to 6.

7. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: Each melting session lasts 10-60 seconds, and the final melting session is held at that temperature for 5-10 minutes.

8. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The electromagnetic stirring process involves alternately turning the electromagnetic field on and off, with each on-time lasting 8-12 seconds, an electromagnetic frequency of 45-60Hz, and a current intensity of 60-100A.

9. The method for preparing a titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The titanium-tantalum-chromium high-entropy alloy material has the following composition by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, Al 9.5%-21%.

10. The titanium-tantalum-chromium high-entropy alloy material prepared by the preparation method of a titanium-tantalum-chromium high-entropy alloy material according to any one of claims 1-9, characterized in that: The titanium-tantalum-chromium high-entropy alloy material has a dendritic structure and secondary dendrites, which contain the Cr2Al phase.

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