Altizrtata high-entropy alloy material and preparation method thereof

Abstract

This invention discloses an AlTiCrZrTa high-entropy alloy material and its preparation method, belonging to the field of high-entropy alloy preparation technology. The high-entropy alloy material, by atomic percentage, comprises the following components: Al 5%-10%, Ti 5%-30%, Cr 1%-25%, Zr 1%-35%, Ta 15%-35%, Nb 20%-35%, W 0.5%-5.5%, and Y 0.1%-5.5%. This invention uses an AlTiCrZrTa high-entropy alloy as the matrix and, by introducing Nb, W, and Y, achieves targeted optimization of the alloy's oxidation resistance, significantly improving the high-temperature oxidation resistance of the alloy system. This enables diversified expansion of the high-entropy alloy's properties, meeting the application needs of aerospace engine hot-end components, high-temperature structural parts, and other fields, effectively solving the problems of insufficient oxidation resistance and cumbersome preparation processes in existing high-entropy alloy systems.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy preparation technology, specifically to an AlTiCrZrTa-based high-entropy alloy material and its preparation method. Background Technology

[0002] High-entropy alloys, due to their high hardness, excellent high-temperature mechanical properties, and structural stability, have become key candidate materials for high-end equipment such as hot-end components of aerospace engines and high-temperature structural parts. Among them, AlTiCrZrTa-based high-entropy alloys have attracted much attention in research and application due to their good comprehensive performance caused by the synergistic effect of multiple principal components. However, existing AlTiCrZrTa-based high-entropy alloys have significant problems with insufficient high-temperature oxidation resistance. In high-temperature service environments of 900℃ and above, a loose and discontinuous oxide film is easily formed on the alloy surface, and oxygen easily diffuses along the grain boundaries, causing preferential oxidation at the grain boundaries, resulting in a persistently high oxidation rate. The oxidation resistance level is mostly at a weak oxidation resistance level or even no oxidation resistance level, which is difficult to meet the long-term service requirements of high-temperature structural parts.

[0003] To improve the high-temperature oxidation resistance of high-entropy alloys, existing technologies often employ modification methods such as surface coating, pre-oxidation treatment, or multi-stage heat treatment. While these methods can improve surface oxidation resistance to some extent, they suffer from cumbersome processes, high preparation costs, and the coating is prone to insufficient interfacial bonding and localized detachment, failing to achieve long-term oxidation protection for the material itself. Furthermore, traditional AlTiCrZrTa-based high-entropy alloys are often prepared using conventional melting processes, which easily lead to severe dendritic segregation. Active components such as Al, Ti, and Zr become excessively enriched between dendrites, forming localized preferential oxidation channels, while antioxidant components such as Cr and Nb are unevenly distributed, making it difficult to form a stable protective oxide film, further restricting the improvement of the alloy's high-temperature oxidation resistance. In addition, some studies have attempted to optimize alloy properties through single-element doping, but it has been difficult to achieve a synergistic improvement in oxidation resistance and microstructure uniformity. The lack of directional composition design and process matching schemes for AlTiCrZrTa-based high-entropy alloys limits the engineering application of this system in high-temperature fields. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide an AlTiCrZrTa-based high-entropy alloy material and its preparation method, thereby solving the problems of insufficient high-temperature oxidation resistance of existing AlTiCrZrTa-based high-entropy alloys and difficulty in achieving synergistic improvement of oxidation resistance and microstructure uniformity.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides an AlTiCrZrTa-based high-entropy alloy material, comprising the following components by atomic percentage: Al 5%-10%, Ti 5%-30%, Cr 1%-25%, Zr 1%-35%, Ta 15%-35%, Nb 20%-35%, W 0.5%-5.5%, and Y 0.1%-5.5%.

[0006] The beneficial effects of this invention are as follows: This invention provides an AlTiCrZrTa-based high-entropy alloy material. Through the doping of Nb, W and Y elements, a continuous, dense and stable composite oxide film mainly composed of Cr(Nb,Ta)O4, TiO2 and Ta2O5 can be formed in the early stage of high-temperature oxidation, which greatly improves the high-temperature oxidation resistance of the alloy system, enabling it to reach the oxidation resistance level, and effectively solving the problem of insufficient oxidation resistance in existing high-entropy alloy systems.

[0007] Furthermore, by atomic percentage, it includes the following components: Al 8%, Ti 15%, Cr 20%, Zr 5%, Ta 20%, Nb 30%, W 1.5% and Y 0.5%.

[0008] Furthermore, the AlTiCrZrTa series high-entropy alloy material has a dendritic structure. The primary dendritic phase is a BCC structure solid solution enriched with Cr / Nb elements, and the interdendritic region is composed of phases mainly formed by Al, Ti and Zr elements.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned AlTiCrZrTa-based high-entropy alloy material, comprising the following steps: S1, Low-temperature pre-melting section processing: Al and Y raw materials are mixed and pre-melted and initially alloyed in the low temperature range of 650-700℃. S2, Medium-temperature alloying section processing: The temperature is raised to the medium temperature range of 1500-1800℃, and Cr, Ti and Zr raw materials are added to the product after preliminary alloying of S1 for alloying processing. S3, High-Temperature Homogenization Section Processing: By heating to a high temperature range of 2200-2500℃, Ta, Nb and W raw materials are added to the S2 alloying product for homogenization processing to obtain AlTiCrZrTa series high entropy alloy material.

[0010] The beneficial effects of this invention are as follows: The preparation method of this invention is simple and controllable, suitable for industrial production, and solves the problems of cumbersome processes in existing methods for improving the oxidation resistance of high-entropy alloys; by adopting a gradient temperature-controlled segmented melting method, the pre-melting and preliminary alloying of low-melting-point and easily oxidized components Al and Y are completed in the low-temperature section, the gradient fusion of medium-melting-point elements such as Cr, Ti and Zr is achieved in the medium-temperature section, reducing component stratification, and finally, high-melting-point components Ta, Nb and W are added in the high-temperature section, achieving uniform melting of all components and homogenizing the matrix composition and microstructure distribution.

[0011] Furthermore, the pretreatment process is as follows: first, use #80, #320, #400, #600, #800 and #1000 sandpaper to polish in sequence, and then use diamond polishing agent to mechanically polish until the surface is free of scratches. Then, use anhydrous ethanol as a cleaning solvent to ultrasonically vibrate and clean the metal raw material for 5-10 minutes.

[0012] Furthermore, the various metal raw materials are prepared according to the design proportions, placed in a water-cooled copper crucible, and then placed in the furnace cavity of a non-consumable vacuum arc melting furnace. A vacuum of 2×10⁻⁶ is first applied. 2 Below Pa, then fill with argon gas to 5-10 Pa.

[0013] Furthermore, the metal raw materials are pure Al, pure Ti, pure Cr, pure Zr, pure Ta, pure Nb, pure W and pure Y with a purity ≥99.9 wt%.

[0014] Furthermore, the heating rate in S1-S3 is 50-80℃ / min, and the holding time in each stage is 20-30 min.

[0015] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: By strictly controlling the heat preservation time and heating rate, the present invention avoids overheating of the melt and oxidation of the components, and achieves uniform melting of all components.

[0016] Furthermore, the smelting in S1-S3 is carried out under electromagnetic stirring.

[0017] Furthermore, S1 employs low-power intermittent electromagnetic disturbances with a power of 500-800 W, each disturbance lasting 1-2 minutes, followed by a 3-4 minute rest period.

[0018] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the present invention avoids splashing of low-melting-point melt by using low-power intermittent electromagnetic disturbance in the low-temperature pre-melting section.

[0019] Furthermore, S2 employs medium-power intermittent electromagnetic disturbances with a power of 1000-1200 W, each disturbance lasting 2-3 minutes, followed by a 2-3 minute rest period.

[0020] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the present invention strengthens component diffusion and breaks the solute enrichment layer by using medium-power intermittent electromagnetic disturbance in the medium-temperature alloying stage.

[0021] Furthermore, S3 employs high-power intermittent electromagnetic disturbances with a power of 1500-1800 W, each disturbance lasting 3-4 minutes, followed by a 1-2 minute rest period.

[0022] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the present invention promotes the polymerization and flotation of oxide inclusions by using high-power intermittent electromagnetic disturbance in the high-temperature alloying section, while ensuring the uniformity of the melt.

[0023] The present invention has the following beneficial effects: 1. Compared with traditional anti-oxidation methods such as surface coating, pre-oxidation treatment or multi-stage heat treatment, this technical solution has the characteristics of outstanding material protection, simple process and excellent performance stability, and can avoid performance degradation caused by local peeling, interface failure and other problems.

[0024] 2. This invention significantly reduces alloy dendrite segregation and homogenizes the matrix composition and microstructure distribution through gradient temperature-controlled segmented melting combined with intermittent electromagnetic disturbance process. It eliminates the excessive enrichment of active components such as Al, Ti, and Zr between dendrites, blocks the rapid channels of local preferential oxidation and internal oxidation, and ensures the continuity of the BCC matrix phase enriched with Cr and Nb antioxidant components. This provides a stable elemental supply for the formation of a protective oxide film during high-temperature oxidation and promotes the formation of a continuous and dense oxide film.

[0025] 3. This invention regulates the chemical activity of each component in the matrix by multi-element doping with trace functional elements such as Y, thereby reducing the selective oxidation driving force of easily oxidized components such as Al and Ti. At the same time, it utilizes the grain boundary segregation effect of Y to suppress the internal diffusion of oxygen along the grain boundaries and the preferential oxidation of grain boundaries. This invention successfully improves the oxidation resistance level of AlTiCrZrTa high-entropy alloys from "weak oxidation resistance" to "oxidation resistance", significantly extending the service life of the material under high temperature extreme environments. Attached Figure Description

[0026] Figure 1 XRD patterns of the as-cast AlTiCrZrTa high-entropy alloy materials prepared in Example 1 and Comparative Examples 1-2; Figure 2 The as-cast Al8Ti prepared in Example 1 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 SEM images and EDS surface scans of high-entropy alloy materials; Figure 3 As-cast Al8Ti prepared for Comparative Example 1 10 Cr 20 Zr 10 Ta 25 Nb 27 SEM images and EDS surface scans of high-entropy alloy materials; Figure 4 As-cast Al8Ti prepared for Comparative Example 2 25 Cr5Zr 30 Ta 30 SEM images and EDS surface scans of Si2 high-entropy alloy materials; Figure 5 The XRD patterns of the as-cast AlTiCrZrTa high-entropy alloy materials prepared in Example 1 and Comparative Examples 1-2 after oxidation at 900℃ for 96 h are shown. Figure 6 The graph shows the continuous weight gain curves of the as-cast AlTiCrZrTa high-entropy alloy materials prepared in Example 1 and Comparative Examples 1-2 after oxidation at 900℃ for 96 hours. Detailed Implementation

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] The metal raw materials used in the following examples are pure Al, pure Ti, pure Cr, pure Zr, pure Ta, pure Nb, pure W, pure Y and pure Si with a purity ≥99.9 wt%.

[0029] Example 1: An Al8Ti 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 The preparation method of high-entropy alloy materials includes the following steps: S1. Preparation of Metal Raw Materials The mass of a single button ingot is 100 g. The following metal elements are prepared according to the mass ratio: Al 8.0 g, Ti 15.0 g; Cr 20.0 g, Zr 5.0 g, Ta 20.0 g, Nb 30.0 g, W 1.5 g and Y 0.5 g.

[0030] S2, Surface pretreatment Impurities and oxides on the surfaces of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were removed by manual polishing. The surfaces were then polished sequentially using #80, #320, #400, #600, #800, and #1000 sandpaper, followed by mechanical polishing with diamond polishing compound until the surfaces were free of scratches. Finally, the elements were ultrasonically cleaned for 5 minutes using anhydrous ethanol as the cleaning solvent, and then dried for later use. S3, furnace loading The processed elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were placed into a water-cooled copper crucible in the order of smelting and then placed in a non-consumable vacuum arc melting furnace. Each time an elemental metal was added, the furnace was evacuated to a vacuum level of 2 × 10⁻⁶. 2 After Pa, backfill with inert argon gas until Pa reaches 5 Pa.

[0031] S4, Smelting Arc melting of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y under argon protection: First, the pre-melting and preliminary alloying of Al and Y low-melting-point easily oxidized components were completed in the low temperature range of 680℃, and electromagnetic disturbance was carried out in an intermittent stirring mode with a power of 600 W, each disturbance lasting 1 min and then settling for 2 min. Then, the temperature was increased to 1600℃ at a heating rate of 50℃ / min, and the medium-melting-point components of Cr, Ti and Zr were added. The temperature was held for 25 min, while intermittent electromagnetic disturbance of 1000 W was performed, each disturbance lasting 2 min, followed by 2 min of rest. Finally, the temperature was increased to 2350℃ at a heating rate of 50℃ / min, and high-melting-point refractory components such as Ta, Nb and W were added. The temperature was held for 25 min, while intermittent electromagnetic disturbance of 1600 W was performed. Each disturbance lasted for 3 min, followed by 2 min of rest. After arc melting, the ingots were cooled to obtain button ingots. The oxide layer on the surface of the ingots was further removed by an angle grinder, and after cooling, Al8Ti was obtained. 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 High-entropy alloy materials.

[0032] Example 2: An Al5Ti 25 Cr 15 Zr 12 Ta 15 Nb 25 The preparation method of W2Y1 high-entropy alloy material includes the following steps: S1. Preparation of Metal Raw Materials Each button ingot has a mass of 100 g. Prepare the following metal elements according to the mass ratio: Al 5.0 g, Ti 25.0 g; Cr 15.0 g, Zr 12.0 g, Ta 15.0 g, Nb 25.0 g, W 2.0 g, and Y 1.0 g.

[0033] S2, Surface pretreatment Impurities and oxides on the surfaces of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were removed by manual polishing. The surfaces were then polished sequentially using #80, #320, #400, #600, #800, and #1000 sandpaper, followed by mechanical polishing with diamond polishing compound until the surfaces were free of scratches. Finally, the elements were ultrasonically cleaned for 5 minutes using anhydrous ethanol as the cleaning solvent, and then dried for later use. S3, furnace loading The processed elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were placed into a water-cooled copper crucible in the order of smelting and then placed in a non-consumable vacuum arc melting furnace. Each time an elemental metal was added, the furnace was evacuated to a vacuum level of 2 × 10⁻⁶. 2 After Pa, backfill with inert argon gas until Pa reaches 5 Pa.

[0034] S4, Smelting Arc melting of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y under argon protection: First, the pre-melting and preliminary alloying of Al and Y low-melting-point easily oxidized components were completed in the low temperature range of 650℃, and electromagnetic disturbance was carried out in an intermittent stirring mode with a power of 500 W, each disturbance lasting 1 min and then settling for 2 min. Then, the temperature was increased to the medium temperature range of 1500℃ at a heating rate of 65℃ / min. Cr, Ti and Zr with medium melting point components were added and kept at the temperature for 20 min. At the same time, 1100 W intermittent electromagnetic disturbance was performed, with each disturbance lasting 2 min and then standing for 2 min. Finally, the temperature was increased to 2200℃ at a heating rate of 65℃ / min, and high-melting-point refractory components such as Ta, Nb and W were added. The temperature was held for 20 min, while intermittent electromagnetic disturbance of 1500 W was performed. After each disturbance for 3 min, the temperature was allowed to stand for 2 min. After arc melting, the resulting ingot was cooled to obtain a button ingot. The oxide layer on the surface of the ingot was further removed using an angle grinder, and after cooling, Al5Ti was obtained. 25 Cr 15 Zr 12 Ta 15 Nb 25 W2Y1 high-entropy alloy material.

[0035] Example 3: A kind of Al 10 Ti 20 Cr 18 Zr8Ta 22 Nb 20 W 0.5 Y 1.5 The preparation method of high-entropy alloy materials includes the following steps: S1. Preparation of Metal Raw Materials Each button ingot has a mass of 100 g. Prepare the following metal elements according to the mass ratio: Al 10.0 g, Ti 20.0 g; Cr 18.0 g, Zr 8.0 g, Ta 22.0 g, Nb 20.0 g, W 0.5 g, and Y 1.5 g.

[0036] S2, Surface pretreatment Impurities and oxides on the surfaces of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were removed by manual polishing. The surfaces were then polished sequentially using #80, #320, #400, #600, #800, and #1000 sandpaper, followed by mechanical polishing with diamond polishing compound until the surfaces were free of scratches. Finally, the elements were ultrasonically cleaned for 5 minutes using anhydrous ethanol as the cleaning solvent, and then dried for later use. S3, furnace loading The processed elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y were placed into a water-cooled copper crucible in the order of smelting and then placed in a non-consumable vacuum arc melting furnace. Each time an elemental metal was added, the furnace was evacuated to a vacuum level of 2 × 10⁻⁶. 2 After Pa, backfill with inert argon gas until Pa reaches 5 Pa.

[0037] S4, Smelting Arc melting of elemental metals Al, Ti, Cr, Zr, Ta, Nb, W, and Y under argon protection: First, the pre-melting and preliminary alloying of Al and Y low-melting-point easily oxidized components were completed in the low temperature range of 700℃, and electromagnetic disturbance was carried out in an intermittent stirring mode with an electromagnetic stirring power of 800 W for 1 min each time, followed by 2 min of standing. Then, the temperature was increased to the medium temperature range of 1800℃ at a heating rate of 80℃ / min. Cr, Ti and Zr components with medium melting points were added and kept at the temperature for 30 min. At the same time, 1200 W intermittent electromagnetic disturbance was performed, with each disturbance lasting 2 min and then standing for 2 min. Finally, the temperature was increased to 2500℃ at a heating rate of 80℃ / min, and high-melting-point refractory components such as Ta, Nb and W were added. The temperature was held for 30 min, while intermittent electromagnetic disturbance of 1800 W was performed. Each disturbance lasted for 3 min, followed by 2 min of rest. After arc melting, the resulting ingot is cooled to obtain a button ingot. The oxide layer on the surface of the ingot is further removed using an angle grinder, and after cooling, Al is obtained. 10 Ti 20 Cr 18 Zr8Ta 22 Nb 20 W 0.5 Y 1.5 High-entropy alloy materials.

[0038] Comparative Example 1: An Al8Ti 10 Cr 20 Zr 10 Ta 25 Nb 27 The high-entropy alloy material was prepared using the same method as in Example 1, except that W and Y elements were not added in Comparative Example 1, and the proportions of each element in the alloy were adjusted as follows: The mass of a single button ingot is 100 g. Prepare the following metal elements in the following mass ratios: Al 8.0 g, Ti 10.0 g; Cr 20.0 g, Zr 10.0 g, Ta 25.0 g, and Nb 27.0 g. The remaining steps remain unchanged.

[0039] Comparative Example 2: An Al8Ti 25 Cr5Zr 30 Ta 30 The Si2 high-entropy alloy material was prepared using the same method as in Example 1, except that Si was added, while Nb, W, and Y were not added, and the proportions of each element in the alloy were adjusted as follows: The mass of a single button ingot is 100 g. Prepare the following metal elements in the following mass ratio: Al 8.0 g, Ti 25.0 g, Cr 5.0 g, Zr 30.0 g, Ta 30.0 g, and Si 2.0 g. The remaining steps remain unchanged.

[0040] Comparative Example 3: A TiTaCrNb high-entropy alloy material is prepared using the same method as in Example 1, except that only Ti, Ta, Cr, and Nb elements are added in this example, and the proportions of each element in the alloy are adjusted as follows: The mass of a single button ingot is 100 g. Prepare elemental metals in the following mass ratio: Ti 12.8 g, Ta 48.4 g, Cr 13.9 g, and Nb 24.9 g. The remaining steps remain unchanged.

[0041] Comparative Example 4: A TiTaCrNbAl 10 The high-entropy alloy material was prepared using the same method as in Example 1, except that only Ti, Ta, Cr, Nb, and Al elements were added in this example, and the proportions of each element in the alloy were adjusted as follows: The mass of a single button ingot is 100 g. Prepare the elemental metals Ti 12.4 g, Ta 46.9 g, Cr 13.5 g, Nb 24.1 g and Al 3.1 g by mass ratio, and the rest of the steps remain unchanged.

[0042] Comparative Example 5: A TiTaCrNbAl 20 The high-entropy alloy material was prepared using the same method as in Example 1, except that only Ti, Ta, Cr, Nb, and Al elements were added in this example, and the proportions of each element in the alloy were adjusted as follows: The mass of a single button ingot is 100 g. Prepare the elemental metals Ti 12.0 g, Ta 45.1 g, Cr 13.0 g, Nb 23.2 g and Al 6.7 g by mass ratio, and the rest of the steps remain unchanged.

[0043] Experimental example: (1) Oxidation test The samples from Example 1 and Comparative Examples 1-4 were cut into 10×10×10 mm pieces using wire electrical discharge machining. 3 The sample was made into a cube; it was then polished with SiC sandpaper in the order of #80, #320, #400, #600, #800, and #1000 until a mirror finish appeared on the surface; it was then polished with diamond polishing agent until no obvious scratches were visible under an optical microscope; the sample was ultrasonically cleaned in anhydrous ethanol for 5 min, and then ultrasonically cleaned with water for another 5 min; it was then dried in a drying oven at a constant temperature of 70℃ for 2 h; the net weight of the dried sample was measured using an electronic balance with an accuracy of 0.0001 g, and the sample was placed in an Al2O3 crucible, and the total weight of the sample and the crucible was measured; the crucible was placed in a tube furnace at 900℃ for oxidation testing, and the sample was removed every two hours, cooled to room temperature, and then weighed.

[0044] After sample polishing, X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterization were 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 As shown, BCC has a body-centered cubic structure. The X-ray energy dispersive spectroscopy (EDS) surface scan results of the backscattered electron (BSE) image are as follows... Figure 2 , Figure 3, Figure 4 As shown, Figure 2 In the image, (a) shows the Al8Ti prepared in Example 1. 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 Alloy as-cast state; Figure 3 In the example, (b) shows Al8Ti prepared in Comparative Example 1. 10 Cr 20 Zr 10 Ta 25 Nb 27 Alloy as-cast state; Figure 4 In the diagram, (c) shows Al8Ti prepared in Comparative Example 2. 25 Cr5Zr 30 Ta 30 Si2 alloy in as-cast state.

[0045] Depend on Figure 1 It can be seen that the AlTiCrZrTa-based high-entropy alloy materials of the present invention with different component ratios all exhibit typical multiphase diffraction characteristics, with the main matrix phase being a BCC structure solid solution, accompanied by the precipitation of various multi-component intermetallic compound phases. With the introduction of high-melting-point components such as Nb, W, and Y, the Al8Ti prepared in Example 1... 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 Alloy and Al8Ti prepared in Comparative Example 1 10 Cr 20 Zr 10 Ta 25 Nb 27 The alloy's main diffraction peaks show significant broadening and angular shift. This phenomenon originates from the significant lattice distortion caused by the difference in atomic radii between the high-melting-point component and the matrix component. Simultaneously, the increased lattice stress and crystal defect density generated during the rapid solidification process in the as-cast state further exacerbate the broadening of the diffraction peaks. (Comparative Example 2: Al8Ti) 25 Cr5Zr 30 Ta 30 The presence of Zr5Si3 silicide characteristic peaks in Si2 alloys is due to the high negative mixing enthalpy of Si and Zr, which causes preferential precipitation of residual liquid phase between dendrites during solidification.

[0046] Depend on Figure 2 It can be seen that the as-cast Al8Ti prepared in Example 1 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y0.5 The alloy exhibits an atypical dendritic morphology, with dendrites rich in Cr, Nb, Ta, and W, and Al, Ti, Zr, and Y distributed relatively uniformly in the interdendritic regions. Compared to traditional dendritic as-cast structures, this alloy shows significantly refined dendritic arms, and the interdendritic second phase transforms from a continuous network to an isolated and dispersed distribution, lacking a continuous brittle phase network. This significantly improves the uniformity of the microstructure, providing a microstructural basis for the synergistic enhancement of the alloy's high-temperature oxidation resistance and toughness.

[0047] Depend on Figure 3 It can be seen that the as-cast Al8Ti prepared in Comparative Example 1 10 Cr 20 Zr 10 Ta 25 Nb 27 The alloy also exhibits a typical dendritic morphology, with dendrites rich in Cr, Nb, and Ta, and Al, Ti, and Zr basically uniformly distributed in the interdendritic regions. Compared to Example 1, Comparative Example 1 is undoped with W and Y. As a result, the number of heterogeneous nucleation sites is reduced, the segregation of Al, Ti, and Zr is intensified, and the interdendritic phase changes from dispersed to a continuous network, resulting in coarser dendrite morphology and a multi-directional framework.

[0048] Depend on Figure 4 It can be seen that the as-cast Al8Ti prepared in Comparative Example 2 25 Cr5Zr 30 Ta 30 The Si2 alloy exhibits a mixed morphology of equiaxed crystals and refined dendrites. The dendritic phase nuclei are enriched with Ta and Cr, accompanied by small amounts of Ti and Si, while the equiaxed crystal phase is enriched with Al, Ti, and Zr, with small amounts of Ta and Cr dissolved in the solid phase. Due to the difference in melting points of the components, non-equilibrium solidification and solute redistribution occur. Ta and Cr nucleate into dendrites first, while Al, Ti, and Zr nucleate into equiaxed crystals in the later stage of the residual liquid phase.

[0049] The XRD patterns of the high-entropy alloy materials prepared in Example 1 and Comparative Examples 1-2 after oxidation at 900℃ for 96 h are shown below. Figure 5 As shown.

[0050] Al8Ti prepared in Example 1 15 Cr 20 Zr5Ta 20 Nb 30 W 1.5 Y 0.5 Alloy and Al8Ti prepared in Comparative Example 1 10 Cr 20 Zr 10 Ta 25 Nb 27After oxidation, the phase composition of the surface oxide layer of the alloy is basically consistent, with six main oxidation products: Cr(Nb,Ta)O4, TiO2, TaO2, NbO2, ZrO2, and Ta2O5. Among these oxidation products, Cr(Nb,Ta)O4, TiO2, and Ta2O5 are thermodynamically stable phases at high temperatures. The Cr(Nb,Ta)O4 composite oxide has a dense rutile crystal structure, forming a continuous protective framework in the oxide layer. This effectively hinders the internal diffusion of oxygen into the alloy matrix and the external diffusion of metal cations, fundamentally inhibiting the continued oxidation reaction. The Ta2O5 refractory metal oxide possesses an extremely high melting point and excellent high-temperature chemical stability. It can fill the pores and grain boundary defects of the oxide film, significantly reducing the elemental diffusion coefficient of the oxide film. Simultaneously, it improves the high-temperature structural integrity of the oxide film, alleviates thermal stress between the oxide film and the substrate, and inhibits cracking and peeling of the oxide film during high-temperature service. Rutile TiO2 can form a dense and compatible composite oxide layer with the above-mentioned composite oxides and refractory metal oxides, further improving the barrier and protective function of the oxide film, and multi-phase synergy enhances the high-temperature oxidation resistance of the alloy.

[0051] Al8Ti prepared in Comparative Example 2 25 Cr5Zr 30 Ta 30 After oxidation, five main oxidation products—CrTaO4, TiTaO4, TiO2, ZrO2, and SiO2—are formed on the surface of the Si2 alloy. Among them, the CrTaO4 and TiTaO4 composite oxides exhibit excellent high-temperature thermodynamic stability and extremely low oxygen ion diffusion rates, forming the main protective framework of the oxide layer and significantly reducing the interdiffusion rate of elements. The ZrO2 phase effectively inhibits high-temperature coarsening of the oxide film grains, refines the oxide layer grains, optimizes the thermal expansion matching between the oxide film and the substrate, alleviates internal stress during thermal cycling, and significantly reduces the risk of oxide film peeling. The SiO2 phase forms a continuous and dense amorphous film at the oxide film grain boundaries and the substrate-oxide film interface, blocking the rapid diffusion channels of elements, significantly reducing the kinetic rate of the oxidation reaction, and passivating the active sites on the substrate surface to inhibit the further development of the oxidation reaction. The synergistic effect of these multiple protective oxide phases constructs a dense, thermally stable, and element-barrier composite protective oxide layer, significantly enhancing the alloy's long-term high-temperature oxidation resistance.

[0052] Example 1, the continuous weight gain curves of the high-entropy alloy materials prepared in Comparative Examples 1-2 after oxidation at 900℃ for 96 h are shown below. Figure 6 As shown.

[0053] Al8Ti prepared in Example 1 15 Cr 20 Zr5Ta 20 Nb 30 W1.5 Y 0.5 The alloy, after 96 hours of continuous oxidation, showed an oxidation rate of only 0.9798 g / m. 2 ·h, this high-entropy alloy belongs to the oxidation resistance level. Al8Ti prepared in Comparative Example 1 10 Cr 20 Zr 10 Ta 25 Nb 27 The alloy, lacking the protective effect of Y element at grain boundaries, exhibits rapid internal diffusion of oxygen along the grain boundaries. After 24 hours, the oxide film protection fails, and the oxidation weight gain rate increases sharply. After 96 hours of continuous oxidation, the oxidation rate reaches 3.7356 g / m³. 2 ·h. Al8Ti prepared in Comparative Example 2 25 Cr5Zr 30 Ta 30 After 96 hours of continuous oxidation, the oxidation rate of the Si2 alloy was 2.7969 g / m. 2 Compared to Comparative Examples 1 and 2, the oxidation rate in Example 1 decreased by 2.7558 g / m³. 2 ·h and 1.8171 g / m 2 ·h.

[0054] Furthermore, the TiTaCrNb alloy prepared in Comparative Example 3 exhibited an oxidation rate of 29.047 g / m after continuous oxidation at 1000℃ for 48 h. 2 ·h, TiTaCrNbAl prepared in Comparative Example 4 10 The alloy, after continuous oxidation at 1000℃ for 48 h, exhibited an oxidation rate of 15.138 g / m. 2 The h values ​​are all significantly higher than those of all embodiments.

[0055] The results show that the present invention can effectively reduce oxidation weight gain by adding appropriate amounts of Nb, W and Y elements, greatly improve the high-temperature oxidation resistance of AlTiCrZrTa high-entropy alloys, and extend the high-temperature service life of the alloys.

[0056] 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. An AlTiCrZrTa-based high-entropy alloy material, characterized in that, The AlTiCrZrTa series high-entropy alloy material comprises the following components by atomic percentage: Al 5%-10%, Ti 5%-30%, Cr 1%-25%, Zr 1%-35%, Ta 15%-35%, Nb 20%-35%, W 0.5%-5.5%, and Y 0.1%-5.5%.

2. The AlTiCrZrTa-based high-entropy alloy material according to claim 1, characterized in that, The AlTiCrZrTa-based high-entropy alloy material has a dendritic structure. The primary dendritic phase is a BCC structure solid solution enriched with Cr / Nb elements, and the interdendritic region is composed of phases mainly formed by Al, Ti and Zr elements.

3. The method for preparing the AlTiCrZrTa-based high-entropy alloy material according to claim 1 or 2, characterized in that, Includes the following steps: S1, Low-temperature pre-melting section processing: Al and Y raw materials are mixed and pre-melted and initially alloyed in the low temperature range of 650-700℃. S2, Medium-temperature alloying section processing: The temperature is raised to the medium temperature range of 1500-1800℃, and Cr, Ti and Zr raw materials are added to the product after preliminary alloying of S1 for alloying processing. S3, High-Temperature Homogenization Section Processing: By heating to a high temperature range of 2200-2500℃, Ta, Nb and W raw materials are added to the S2 alloying product for homogenization processing to obtain AlTiCrZrTa series high entropy alloy material.

4. The method for preparing AlTiCrZrTa-based high-entropy alloy materials according to claim 3, characterized in that, The metal raw material is first pretreated. The pretreatment process is as follows: first, it is polished with sandpaper of #80, #320, #400, #600, #800 and #1000 in sequence, and then mechanically polished 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.

5. The method for preparing AlTiCrZrTa-based high-entropy alloy material according to claim 3, characterized in that, The metal raw materials are pure Al, pure Ti, pure Cr, pure Zr, pure Ta, pure Nb, pure W and pure Y with a purity of ≥99.9 wt%.

6. The method for preparing AlTiCrZrTa-based high-entropy alloy material according to claim 3, characterized in that, The heating rate in S1-S3 is 50-80℃ / min, and the holding time in each stage is 20-30 min.

7. The method for preparing AlTiCrZrTa-based high-entropy alloy materials according to claim 3, characterized in that, The S1 uses low-power intermittent electromagnetic disturbance with a power of 500-800 W, each disturbance lasting 1-2 minutes, followed by a rest period of 3-4 minutes.

8. The method for preparing AlTiCrZrTa-based high-entropy alloy materials according to claim 3, characterized in that, The S2 uses medium-power intermittent electromagnetic disturbance with a power of 1000-1200 W, each disturbance lasting 2-3 minutes, followed by a rest period of 2-3 minutes.

9. The method for preparing AlTiCrZrTa-based high-entropy alloy material according to claim 3, characterized in that, The S3 uses high-power intermittent electromagnetic disturbance with a power of 1500-1800 W, each disturbance lasting 3-4 minutes, followed by a rest period of 1-2 minutes.

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