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

Abstract

The application discloses a titanium-tantalum-chromium high-entropy alloy material and a preparation method thereof. By introducing a specific content of Al elements, Cr2Al strengthening phases are generated, and more importantly, strong lattice distortion is induced, which greatly promotes the rapid diffusion of Al and Cr atoms to the surface, so that a continuous, dense and stable composite oxide film mainly composed of Al2O3 and Cr2O3 can be formed at the initial stage of high-temperature oxidation, and the inward diffusion of oxygen is effectively blocked. By adjusting the content of Al elements, the oxidation rate of the alloy is as low as 3.671 g / m2.h after static oxidation at 1000 DEG C for 48 hours, and the high-temperature service life and reliability of the TiTaCr high-entropy alloy are significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-entropy alloy preparation, and particularly relates to a titanium-tantalum-chromium high-entropy alloy material and a preparation method thereof. BACKGROUND

[0002] The traditional high-temperature alloys such as Fe, Co and Ni bases cannot meet the material requirements in the field of aerospace at present. With the continuous development of advanced aero-engines and gas turbines, advanced high-temperature structural materials have become the core elements for improving the service performance of engines, prolonging the service life, and reducing energy consumption and cost. Since the high-temperature hot-end components are in a harsh service condition, they are subjected to high-temperature oxidation, temperature impact and strong airflow scouring, and thus there is an urgent need to prepare new high-temperature alloys with high-temperature strength and high-temperature oxidation resistance.

[0003] Refractory high-entropy alloys (RHEAs) are a kind of potential new high-temperature structural materials, however, the insufficient high-temperature oxidation resistance has become a key bottleneck restricting the application of RHEAs. The application fundamentally improves the oxidation resistance by regulating micro defects from the structural design of the material. The application induces lattice distortion by introducing relevant oxidation-resistant elements, utilizes the rapid diffusion effect generated by the distortion to realize efficient transport of oxidation-resistant elements and rapid self-generation of protective films, and provides a new solution for solving the high-temperature oxidation failure problem of RHEAs. The application provides a new idea for designing and developing heat-resistant alloy materials, and is expected to solve the bottleneck of traditional alloys in structure and performance. SUMMARY

[0004] In order to solve the above technical problems, the first object of the application is to provide a preparation method of a titanium-tantalum-chromium high-entropy alloy material. The preparation method of the application is simple and controllable, and is suitable for industrial production.

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

[0006] In order to achieve the above object, the application adopts the following preparation method:

[0007] The preparation method of the titanium-tantalum-chromium high-entropy alloy material of the application is that each metal raw material is prepared according to the designed proportion, and repeated melting is carried out under a protective atmosphere, so that the titanium-tantalum-chromium high-entropy alloy material is obtained.

[0008] The current intensity of the first melting is 40-60 A, then the current intensity is increased by 5-15 A for the second to N-1 times of melting in turn, and finally the current intensity is reduced by 20-25 A for the N times of melting on the basis of the N-1 times of melting;

[0009] The melting is carried out under electromagnetic stirring;

[0010] The titanium-tantalum-chromium high-entropy alloy material is composed of Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 5%-25% in atomic percentage.

[0011] The titanium-tantalum-chromium high-entropy alloy material provided by the application generates the Cr2Al strengthening phase by introducing a specific content of Al elements, and more importantly, strong lattice distortion is induced by controlling the preparation process and the composition. The preparation method of the application uses the stepwise temperature rising melting method to make the Al elements fully diffuse and solid dissolve, increase the influence on the lattice distortion, promote the uniform precipitation of the nanoscale Cr2Al phase, and promote the uniform distribution of the solute elements by electromagnetic stirring, so as to ensure the uniformity of the lattice distortion effect and greatly promote the rapid diffusion of Al and Cr atoms to the surface. In addition, the addition of Nb can effectively reduce the lattice distortion effect of Al and Cr, and the Nb element has a larger atomic radius than Ti, which can effectively block the vacancies and channels in the TiO2 lattice, significantly reduce the diffusion rate of oxygen ions and titanium ions in TiO2, and make the oxide layer more dense, while promoting the formation of the Al2O3 film, so that a continuous, dense and stable composite oxide film mainly composed of Al2O3 and Cr2O3 can be quickly formed at the initial stage of high-temperature oxidation, effectively blocking the inward diffusion of oxygen, and greatly improving the high-temperature oxidation resistance. 5+ The atomic radius of Nb is different from that of Ti 4+ It can dissolve into the TiO2 lattice, effectively block the vacancies and channels in the lattice, significantly reduce the diffusion rate of oxygen ions and titanium ions in TiO2, and make the oxide layer more dense, while promoting the formation of the Al2O3 film, so that a continuous, dense and stable composite oxide film mainly composed of Al2O3 and Cr2O3 can be quickly formed at the initial stage of high-temperature oxidation, effectively blocking the inward diffusion of oxygen, and greatly improving the high-temperature oxidation resistance.

[0012] It is found that when the stepwise temperature rising melting method is used in the application, the first to N-1 all use the way of increasing the current intensity, i.e. increasing the temperature, while the last time needs to be cooled down, i.e. reducing the current to melt, which not only reduces the fluctuation of the molten pool during melting, but also is beneficial to the uniformity of the composition and reduces the element segregation, while avoiding the overheating and volatilization of metal elements, ensuring the stability of the alloy composition and organization.

[0013] In the preferred scheme, the metal raw material is first pretreated, and the pretreatment process is to polish with sandpaper of #80, #320, #400, #600, #800 and #1000 in turn, and then mechanically polish with diamond polishing agent until the surface is free of scratches, and then oscillate and clean the metal raw material in ultrasonic waves for 5-10 min using anhydrous ethanol as the cleaning solvent.

[0014] In the preferred scheme, the metal raw materials are taken in the designed proportion, placed in a water-cooled copper crucible, and placed in the furnace cavity of a non-consumable vacuum arc melting furnace, first vacuumized to 2x10 2 Pa, and then filled with argon to 5-10 Pa.

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

[0016] Further preferably, the pure Ta and the pure Nb are placed at the bottom of the crucible, then the pure Cr and the pure Ti are placed above the pure Ta and the pure Nb as a transition layer, and finally the pure Al is added.

[0017] Preferably, the number N of melting is 4-6 times.

[0018] Preferably, the time of any one melting is 10-60 s, and after the last melting is completed, the temperature is maintained for 5-10 min.

[0019] In actual operation, after the previous melting is completed, the melting button sample is turned over before the next melting program.

[0020] Preferably, the process of electromagnetic stirring is to alternately turn on and off the electromagnetic field, each time the electromagnetic field is turned on for 8-12 s, the electromagnetic frequency is 45-60 Hz, and the current intensity is 60-100 A.

[0021] Preferably, the titanium-tantalum-chromium high-entropy alloy material comprises, by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 9.5%-21%.

[0022] Further preferably, the titanium-tantalum-chromium high-entropy alloy material comprises, by atomic percentage: Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 18%-21%.

[0023] The application also provides a titanium-tantalum-chromium high-entropy alloy material prepared by the above preparation method.

[0024] Principle and advantage:

[0025] The atomic radius of Al element is much smaller than that of the main elements Ta, Nb and Ti in the matrix. When Al atoms are solid-solved into the BCC main phase lattice, they will replace the larger atomic positions, resulting in strong local compression strain around the lattice, thereby introducing serious lattice distortion in the entire alloy. The lattice distortion increases the defect density, such as dislocations and grain boundaries, in the titanium-tantalum-chromium high-entropy alloy. The presence of these defects provides a channel for the rapid diffusion of Al and Cr, promoting the formation of their oxides. During high-temperature oxidation, sufficient Al and Cr atoms rapidly diffuse to the alloy surface through the rapid diffusion channel, preferentially oxidizing to form a continuous, dense and well-adhesive Al(TaO4), (AlTiTa)2O 12 and CrTaO4 mixed oxide film. This protective film can effectively block the invasion of oxygen, thereby greatly reducing the oxidation rate and achieving a qualitative leap in the bulk oxidation resistance.

[0026] The present application uses TiTaCrNb high-entropy alloy as the matrix, and by introducing a specific content of Al element, not only Cr2Al strengthening phase is generated, but more importantly, strong lattice distortion is induced through process control and composition control. The preparation method of the present application uses stepwise heating melting method to make Al element fully diffuse and solid-solve, increase its influence on lattice distortion, promote the uniform precipitation of nanoscale Cr2Al phase, and through electromagnetic stirring, promote the uniform distribution of solute elements, ensure the uniformity of lattice distortion effect, greatly promote the rapid diffusion of Al and Cr atoms to the surface, so that a continuous, dense and stable composite oxide film mainly composed of Al2O3 and Cr2O3 can be formed at the initial stage of high-temperature oxidation, effectively blocking the inward diffusion of oxygen; thereby greatly improving the high-temperature oxidation resistance.

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

[0028] 1. The present application breaks through the traditional idea of simply relying on the content of oxidation-resistant elements, actively introduces lattice distortion as a new variable, utilizes the rapid diffusion channel generated by distortion, realizes efficient utilization of oxidation-resistant elements (Al, Cr) and rapid self-generation of protective film, and fundamentally solves the high-temperature oxidation problem from the perspective of kinetics.

[0029] 2. Through the synergistic effect of Al element doping and lattice distortion, the present application successfully improves the oxidation resistance of TiTaCrNb high-entropy alloy, and significantly prolongs the service life of the material in high-temperature extreme environment.

[0030] 2. The stepwise melting and intermittent electromagnetic stirring process provided by the present application can effectively control the distribution of Al element and the degree of lattice distortion, the process parameters are clear and reproducible, and it lays a solid foundation for the industrialized preparation of high-performance oxidation-resistant refractory high-entropy alloy. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 X-ray diffraction spectra of as-cast TiTaCrNbAl high-entropy alloy materials prepared for Example 1, Example 2 and Example 3.

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

[0033] Figure 3 SEM photos and EDS area scan results of as-cast TiTaCrNbAl high-entropy alloy materials prepared for Example 1, Example 2 and Example 3; wherein: (a) is TiTaCrNb alloy prepared for Example 1; (b) is TiTaCrNbAl alloy prepared for Example 2; (c) is TiTaCrNbAl alloy prepared for Example 3. 10 20

[0034] Figure 4 SEM-EDS enlarged photos of dendritic zone of as-cast TiTaCrNbAl high-entropy alloy material prepared for Example 3. 20

[0035] Figure 5 SEM photos and EDS area scan results of as-cast TiTaCrZrV high-entropy alloy materials prepared for Comparative Example 1, Comparative Example 2 and Comparative Example 3; wherein: (a) is TiTaZrV alloy prepared for Comparative Example 1; (b) is TiTaCrZrV alloy prepared for Comparative Example 2; (c) is TiTaCrZrV alloy prepared for Comparative Example 3. 10 20

[0036] Figure 6 X-ray diffraction spectra of TiTaCrNbAl high-entropy alloy materials prepared for Example 1, Example 2 and Example 3 after 1000°C oxidation for 48h.

[0037] Figure 7 Continuous weight gain curves of TiTaCrNbAl high-entropy alloy materials prepared for Example 1, Example 2 and Example 3 after 1000°C oxidation for 48h. DETAILED DESCRIPTION

[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 of the high-entropy alloy material is 100 g, and the mass ratio of Ti:Ta:Cr:Nb:Al is 12.4%:46.9%:13.5%:24.1%:3.1%. Therefore, the required mass is: Ti-12.4 g; Ta-46.9 g; Cr-13.5 g; Nb-24.1 g; and Al-3.1 g.

[0047] Metal element surface pretreatment: the metal elements Ta, Ti, Cr, Nb, and Al are polished by a manual polishing method to remove surface impurities and oxides. #80, #320, #400, #600, #800, and #1000 sandpaper are used in sequence for polishing, and diamond polishing agent is used for mechanical polishing until the surface is scratch-free. Then, the metal elements Ta, Ti, Cr, Nb, and Al are cleaned in an ultrasonic wave for 5 minutes using anhydrous ethanol as a cleaning solvent, and then dried for use.

[0048] The treated metal elements Ta, Ti, Cr, Nb, and Al are placed in a water-cooled copper crucible. Pure Ta and pure Nb are placed at the bottom of the crucible, then pure Cr and pure Ti are placed above the pure Ta and pure Nb as a transition layer, and finally pure Al is added and placed in a non-consumable vacuum arc melting furnace. After vacuumizing to 2×10 2 Pa, the inert gas argon is charged to 5 Pa.

[0049] The metal elements Ta, Ti, Cr, Nb, and Al are arc melted under the protection of argon. The first melting uses a lower current (60 A) to initially alloy the metals. The current is gradually increased to 80 A, 90 A, and 100 A for the subsequent four times of melting. The melting time is 1 min. The last melting is adjusted back to 80 A and kept for 8 minutes. At the same time, intermittent strong stirring mode is used for electromagnetic stirring to increase the uniformity of alloy mixing. The electromagnetic field is alternately turned on and off at a frequency of 50 Hz, each time for 10 seconds, and the current intensity is 80 A. After multiple arc melting, the button ingot is obtained after cooling. The oxide layer on the surface of the obtained button ingot is further polished off by an angle grinder. After cooling, the as-cast TiTaCrNbAl 10 high-entropy alloy, marked as Al10.

[0050] Example 3

[0051] A TiTaCrNbAl 20High-entropy alloy material, its preparation process is consistent with example 2, the difference is that Al element is added, and the proportion of each element of the alloy is also different, the mass of a single button ingot is 100g, and the mass ratio of Ti:Ta:Cr:Nb:Al is 12.0%:45.1%:13.0%:23.2%:6.7%, the required mass is respectively: Ti-12.0g; Ta-45.1g; Cr-13.0g; Nb-23.2g; Al-6.7g; the finally prepared as-cast TiTaCrNbAl 20 High-entropy alloy, marked as Al20.

[0052] Comparative example 1

[0053] Other conditions are the same as example 2, only this comparative example provides a TiTaZrV high-entropy alloy material, the mass of a single button ingot is 100g, and the mass ratio of Ti:Ta:Zr:V is 12.9%:48.8%:24.5%:13.8%, the required mass is respectively: Ti-12.9g; Ta-48.8g; Zr-24.5g; V-13.8g, the finally prepared as-cast TiTaZrV high-entropy alloy is marked as Cr0.

[0054] Comparative example 2

[0055] Other conditions are the same as example 2, only this comparative example provides a TiTaCr 10 ZrV high-entropy alloy material, the mass of a single button ingot is 100g, and the mass ratio of Ti:Ta:Cr:Zr:V is 12.3%:46.2%:5.3%:23.2%:13.0%, the required mass is respectively: Ti-12.3g; Ta-46.2g; Cr-5.3g; Zr-23.2g; V-13.0g; the finally prepared as-cast TiTaCr 10 ZrV high-entropy alloy is marked as Cr10.

[0056] Comparative example 3

[0057] Other conditions are the same as example 2, only this comparative example provides a TiTaCr 20 ZrV high-entropy alloy material, the mass ratio of Ti:Ta:Cr:Zr:V is 11.4%:42.8%:12.3%:21.5%:12.1%, the required mass is respectively: Ti-11.4g; Ta-42.8g; Cr-12.3g; Zr-21.5g; V-12.1g; the finally prepared as-cast TiTaCr 20 ZrV high-entropy alloy is marked 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] Furthermore, the comparative example 4 constant current smelting preparation of TiTaCrNbAl 10 alloy, after 48 hours of continuous oxidation, the oxidation rate was 135.452 g / m 2 ·h, the comparative example 5 continuously stirred preparation of TiTaCrNbAl 10 alloy, after 48 hours of continuous oxidation, the oxidation rate was 150.334 g / m 2 ·h, which are all higher than example 2.

[0072] It can be seen that the appropriate amount of Nb and Al elements cooperated with the process of the application can reduce the oxidation weight gain, greatly improve the high-temperature oxidation resistance of TiTaCr high-entropy alloy, and prolong the high-temperature service life of the alloy.

[0073] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a titanium-tantalum-chromium high-entropy alloy material, characterized in that: The titanium-tantalum-chromium high-entropy alloy material is obtained by repeatedly melting the metal raw materials in a protective atmosphere according to a designed proportion. The current intensity for the first melting is 40-60 A, then the current intensity is increased by 5-15 A for the second to N-1 melting, and finally the current intensity is reduced by 20-25 A for the N melting based on the N-1 melting. The melting is performed under electromagnetic stirring. The titanium-tantalum-chromium high-entropy alloy material comprises, by atomic percentage, Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 5%-25%.

2. The preparation method of the titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The metal raw materials are pretreated by polishing with sandpaper of #80, #320, #400, #600, #800 and #1000 in sequence, and then mechanically polishing with diamond polishing agent until no scratches are left on the surface, and then oscillating cleaning in ultrasonic waves for 5-10 min with anhydrous ethanol as the cleaning solvent.

3. The preparation method of the titanium-tantalum-chromium high-entropy alloy material according to claim 1, characterized in that: The metal raw materials are proportioned according to the design, placed in a water-cooled copper crucible, and placed in a furnace cavity of a non-consumable vacuum arc melting furnace. First, vacuum is extracted to 2×10 2 Pa, and then argon is filled to 5-10 Pa.

4. The preparation method of the 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 preparation method of the titanium-tantalum-chromium high-entropy alloy material according to claim 4, characterized in that: The pure Ta and pure Nb are placed at the bottom of the crucible, then the pure Cr and pure Ti are placed above the pure Ta and pure Nb as a transition layer, and finally the pure Al is added.

6. The method of claim 1, wherein the method further comprises: The number of melting is 4-6 times. ​ 7. The method of claim 1, wherein the method further comprises: annealing the titanium-tantalum-chromium high-entropy alloy material at a temperature of 800-1200 °C for 1-10 hours. The time for any one melting is 10-60 s, and the last melting is kept for 5-10 min after completion.

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

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 comprises, by atomic percentage, Ti 15%-30%, Ta 15%-30%, Cr 15%-30%, Nb 15%-30%, and Al 9.5%-21%.

10. The titanium-tantalum-chromium high-entropy alloy material prepared by the method 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, and the secondary dendrites contain Cr2Al phase.

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