A refractory high-entropy alloy resistant to high-temperature molten aluminum erosion and erosion-wear, its preparation method and application

Abstract

This invention discloses a refractory high-entropy alloy resistant to high-temperature molten aluminum corrosion and erosion-wear, its preparation method, and its applications. The refractory high-entropy alloy of this invention comprises, by atomic percentage: 40-50 at.% Nb, 35-40 at.% Ti, 4-10 at.% Mo, 4.5-5 at.% Cr, and no more than 10 at.% Al. This invention obtains the refractory high-entropy alloy by mixing and melting the raw materials under a protective atmosphere. The refractory high-entropy alloy ingot of this invention has a single-phase BCC microstructure, exhibiting stable structure, good mechanical properties, and excellent resistance to molten aluminum corrosion and erosion-wear. The Nb-Ti-Mo-Cr based refractory high-entropy alloy resistant to molten aluminum corrosion and erosion-wear prepared using this invention can significantly improve the service life of components, reduce replacement frequency, and has high economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of erosion-resistant and erosion-wear-resistant metallic materials, specifically relating to a Nb-Ti-Mo-Cr based refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear, its preparation method and application. Background Technology

[0002] In the smelting, forming, and hot-dip galvanizing processes of pure aluminum and aluminum alloys, the parts of the production equipment that come into direct contact with the high-temperature molten aluminum are prone to erosion and erosion-wear failure, leading to a shortened service life of the equipment and severely impacting production efficiency. The failure process of materials in molten aluminum mainly consists of two aspects: first, the material diffuses and reacts with the molten aluminum, creating a reaction layer between the material and the aluminum; second, the reaction layer peels off due to mechanical and thermal stresses, exposing fresh material and accelerating the erosion process. Therefore, materials resistant to high-temperature molten aluminum erosion and erosion-wear not only need to be structurally stable and resistant to reaction with molten aluminum at high temperatures, but also need sufficient hardness to withstand high-temperature wear. Furthermore, they must possess certain high-temperature mechanical properties to ensure their service life in high-temperature environments.

[0003] High-entropy alloys were first proposed by Taiwanese scholar Yeh Chun-wei in 2004 and have attracted much attention due to their excellent comprehensive properties. Subsequently, refractory high-entropy alloys with refractory metal elements (broadly defined as metal elements with melting points above 1650℃) as the main components have emerged. These materials have good mechanical properties at high temperatures. At the same time, the solubility of refractory metal elements in high-temperature aluminum melt is often very low. According to existing research literature, equiatomic MoNbTi has a single-phase BCC (body-centered cubic) structure. This alloy has excellent tribological properties, with a yield strength of 1100 MPa at room temperature. At the same time, MoNbTi also has excellent high-temperature mechanical properties, with a yield strength of 504 MPa at 1000℃ (Zhu W, Zhao C, Zhang Y, et al. Achieving exceptional wear resistance in a compositionally complex alloy viatuning the interfacial structure and chemistry[J]. Acta Materialia, 2020,188: 697-710.). Adding Al to MoNbTi results in an equiatomic-ratio MoNbTiAl refractory high-entropy alloy that retains a single-phase BCC structure, exhibiting a yield strength of 1100 MPa at room temperature and improved high-temperature mechanical properties, with a yield strength of 540 MPa at 1000℃. However, adding Cr to MoNbTiAl results in a decrease in the yield strength of the equiatomic-ratio MoNbTiAlCr alloy at both room temperature and high temperature. This is because the excessively high Cr content leads to a microstructure composed of BCC+Laves phases (Senkov ON, Gorsse S, Miracle D B. High temperature strength of refractory complex concentrated alloys[J]. Acta Materialia, 2019, 175: (394-405.) The presence of the Laves phase increases its brittleness, making preparation more difficult and processing and shaping challenging. Furthermore, due to the structural and chemical mismatch between the Laves and BCC phases, interfacial reactions are prone to occur, reducing the structural stability of equiatomic MoNbTiAlCr and making it difficult to apply under extreme conditions. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a Nb-Ti-Mo-Cr based refractory high-entropy alloy that is resistant to erosion and erosion-wear, and to provide its preparation method. This refractory high-entropy alloy has excellent resistance to aluminum melt erosion and erosion-wear.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear, comprising, by atomic percentage: 40-50 at.% Nb, 35-40 at.% Ti, 4-10 at.% Mo, 4-5 at.% Cr, and no more than 10 at.% Al.

[0007] Preferably, by atomic percentage, it includes: 40.5-45 at.% Nb, 36-40 at.% Ti, 9-10 at.% Mo, 4.5-5 at.% Cr, and no more than 10 at.% Al.

[0008] Preferably, by atomic percentage, it comprises: 40.5-45 at.% Nb, 36-40 at.% Ti, 9-10 at.% Mo, 4.5-5 at.% Cr, and 4-10 at.% Al. More preferably, by atomic percentage, it comprises: 40.5-45 at.% Nb, 36-40 at.% Ti, 9-10 at.% Mo, 4.5-5 at.% Cr, and 4-8 at.% Al.

[0009] Preferably, the refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear has a body-centered cubic crystal structure at room temperature, a compressive strength greater than or equal to 1 GPa, and a compressive fracture strain greater than or equal to 45%.

[0010] Preferably, the volume loss of the refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear after being eroded by aluminum melt at 750℃ for 8 hours does not exceed 7.5 vol.%, and the volume loss after being eroded and worn by aluminum melt at 750℃ does not exceed 9.2 vol.%.

[0011] The above-mentioned method for preparing refractory high-entropy alloys resistant to high-temperature aluminum melt erosion and erosion-wear includes the following steps:

[0012] The raw materials of refractory high-entropy alloys are mixed and smelted under a protective atmosphere to obtain refractory high-entropy alloys that are resistant to high-temperature aluminum melt erosion and erosion-wear.

[0013] Preferably, the melting process is repeated 5 times or more;

[0014] Preferably, the melting is vacuum induction melting or vacuum arc melting;

[0015] More preferably, the vacuum arc melting current is 300-400A, and the melting time is 1-3 minutes.

[0016] Preferably, the protective atmosphere is argon;

[0017] Preferably, the pressure of the protective atmosphere is 0.5-1 atmosphere;

[0018] Preferably, the protective atmosphere is first evacuated to a vacuum of 1×10⁻⁶. -2 The solution is obtained by filling with a protective gas at a pressure below 1 Pa.

[0019] Preferably, the raw material for the refractory high-entropy alloy is a metallic element or an intermediate alloy;

[0020] More preferably, the purity of the elemental metal or intermediate alloy is not less than 99.9%.

[0021] More preferably, the metallic element is Ti, Cr, or Al;

[0022] More preferably, the intermediate alloy is Ti-Nb and Ti-Mo.

[0023] Applications of the aforementioned refractory high-entropy alloys in the preparation of high-temperature molten aluminum erosion and erosion-wear resistant molds, crucibles, nozzles, and stirring rods.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) The refractory high entropy alloy based on Nb-Ti-Mo-Cr, which is resistant to aluminum melt erosion and erosion-wear, prepared by the present invention uses four refractory metals, namely niobium (Nb), titanium (Ti), chromium (Cr) and molybdenum, as the main components. By controlling the appropriate Cr content, the formation of the harmful brittle phase Laves phase is avoided. At the same time, the addition of Nb element to the alloy can improve the wear resistance. Moreover, Nb has very low solubility in aluminum melt, which can make the alloy maintain structural stability in aluminum melt. Ti and Mo can improve the high temperature mechanical properties of the alloy. In addition, the aluminum (Al) content is controlled to reduce the chemical potential difference between the alloy and the aluminum melt, slow down the reaction rate between the refractory high entropy alloy and the aluminum melt, and ensure that the Al content is not too high, so as to prevent the reduction of the alloy's plasticity, prevent the formation of microcracks in the alloy products in molten aluminum, reduce the reliability of the reaction interface and the alloy matrix, and thus reduce its resistance to aluminum melt erosion and erosion-wear.

[0026] (2) The Nb-Ti-Mo-Cr based refractory high-entropy alloy prepared by this invention has a single-phase BCC structure with typical dendritic morphology in the as-cast state, without precipitates and with stable structure. In addition to meeting the performance requirements of various aluminum melt erosion and erosion-wear conditions, it also has good high-temperature mechanical properties. The compressive strength at room temperature reaches 1.0-1.6 GPa, and the compressive fracture strain is greater than or equal to 45%; the hardness at room temperature reaches 350-450 HV, and the high-temperature hardness at 750℃ reaches 270-390 HV. It is a new type of aluminum melt erosion and erosion-wear resistant material, which is expected to replace the application of H13 steel.

[0027] (3) The high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy material prepared by this invention, under the test conditions of aluminum melt temperature of 750℃, applied load of 10N, friction pair material of Si3N4, friction pair rotation speed of 60r / min, and erosion-wear time of 30min, after being tested by a ring-block type aluminum melt erosion-wear machine (test method refers to patent number: ZL201010526678.5), its high-temperature aluminum melt erosion and erosion-wear performance is 15-30 times higher than that of H13 steel, a commonly used hot work die steel material in industry. At the same time, the high-temperature hardness at 750℃ reaches 270-390 HV, and it has excellent wear resistance at high temperature;

[0028] (4) The Nb-Ti-Mo-Cr-based refractory high-entropy alloy that is resistant to high-temperature aluminum melt erosion and erosion-wear prepared by the present invention has a melting point much lower than that of common refractory alloys. It can be prepared by melting and forming, and the preparation process is simple and can be mass-produced. Attached Figure Description

[0029] Figure 1 The microstructure of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 1 is shown.

[0030] Figure 2 The XRD diffraction patterns of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 1 are shown.

[0031] Figure 3 The room temperature compressive stress-strain curves of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 1 are shown.

[0032] Figure 4 The images show the interface morphology of the high-temperature resistant aluminum melt erosion-resistant refractory high-entropy alloy prepared in Example 1 after aluminum melt erosion.

[0033] Figure 5 The microstructure of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 2 is shown.

[0034] Figure 6 The XRD diffraction patterns of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 2 are shown.

[0035] Figure 7 The room temperature compressive stress-strain curves of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 2 are shown.

[0036] Figure 8 The images show the interface morphology of the high-temperature resistant aluminum melt erosion and the erosion-wear refractory high-entropy alloy prepared in Example 2 after aluminum melt erosion.

[0037] Figure 9 The microstructure of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 3 is shown.

[0038] Figure 10 The XRD diffraction patterns of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 3 are shown.

[0039] Figure 11 The room temperature compressive stress-strain curves of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 3 are shown.

[0040] Figure 12 The images show the interface morphology of the high-temperature resistant aluminum melt erosion and the erosion-wear refractory high-entropy alloy prepared in Example 3 after aluminum melt erosion.

[0041] Figure 13 The microstructure of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 4 is shown.

[0042] Figure 14 The XRD diffraction patterns of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 4 are shown.

[0043] Figure 15 The room temperature compressive stress-strain curves of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy prepared in Example 4 are shown.

[0044] Figure 16 The images show the interface morphology of the high-temperature resistant aluminum melt erosion and the erosion-wear refractory high-entropy alloy prepared in Example 4 after aluminum melt erosion.

[0045] Figure 17 The figures show line graphs of volume loss due to aluminum melt erosion and aluminum melt erosion-wear of the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy and H13 steel prepared in Examples 1-4.

[0046] Figure 18The bar chart shows the volume loss of aluminum melt erosion in the high-temperature resistant aluminum melt prepared in Examples 1-4, as well as the erosion-wear refractory high-entropy alloy and H13 steel.

[0047] Figure 19 The bar chart shows the volume loss of aluminum melt erosion and wear of the high-temperature resistant aluminum melt prepared in Examples 1-4, as well as the erosion-wear of refractory high-entropy alloys and H13 steel. Detailed Implementation

[0048] To facilitate understanding of the present invention, a more comprehensive and detailed description will be provided below in conjunction with the accompanying drawings and examples. However, the implementation and protection of the present invention are not limited thereto. It should be noted that, unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art, and reagents or instruments whose manufacturers are not specified are considered to be conventional products purchased commercially. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention.

[0049] A Nb-Ti-Mo-Cr based refractory high-entropy alloy material resistant to high-temperature aluminum melt erosion and erosion-wear, comprising, by atomic percentage, 40-50 at.% Nb, 35-40 at.% Ti, 4-8 at.% Mo, 4-5 at.% Cr, and 0-10 at.% Al;

[0050] The preparation method includes the following steps:

[0051] Ingredients: Weigh out Ti, Cr, Ti-Nb master alloy, Ti-Mo master alloy, and Al raw material particles according to atomic ratio and mix them to obtain a mixture;

[0052] Furthermore, the Ti-Nb master alloy and Ti-Mo master alloy, by mass percentage, have the following compositions: 30Ti-70Nb and 50Ti-50Mo.

[0053] Melting: The mixture is melted more than five times in an argon atmosphere. After each melting, the resulting ingot is flipped over before the next melting.

[0054] Furthermore, the purity of the Ti, Cr, Ti-Nb master alloy, Ti-Mo master alloy, and Al raw material particles is not less than 99.9%;

[0055] Furthermore, the purity of the argon gas is not less than 99.99%; the atmospheric pressure of the argon gas atmosphere is 0.5-1 atmosphere.

[0056] Furthermore, the melting is vacuum arc melting, and the melting parameters are: current 300-400A melting for 3 minutes;

[0057] Furthermore, the furnace cavity of the smelting furnace is evacuated to a vacuum level of less than 5.0 × 10⁻⁶ m² before smelting. -3 Pa, then argon gas is introduced to melt the pure titanium test sample inside to absorb the residual oxygen in the cavity. After melting, the pure titanium sample is observed. If it still has a metallic luster, then further melting is carried out.

[0058] Furthermore, the melting is vacuum arc melting, with melting parameters of 340-400A current for 1 minute;

[0059] More preferably, the number of smelting cycles is eight or more.

[0060] The specific experimental methods for testing the high-temperature resistant aluminum melt erosion-wear performance in the following embodiments refer to the experimental methods described in patent document ZL 201010526678.5. The specific test conditions are: rotation speed 60 r / min; aluminum melt temperature 750℃; load 10 N; test time 30 min.

[0061] Example 1

[0062] According to Nb 45 Ti 40 Mo 10 After converting the atomic ratios of each component in the Cr5 refractory high-entropy alloy to their mass percentages (wt.%), a total mass of (80±0.1g) of pure metal raw materials was weighed using an analytical balance. The purity of the Ti, 30Ti-70Nb, and Cr, 50Ti-50Mo raw materials used was not less than 99.9%. The mass of Cr was adjusted by 1.5% as burn-off loss. The prepared metal raw materials were then placed in a copper mold crucible within a vacuum arc melting furnace. The furnace chamber pressure was evacuated to 5.5×10⁻⁶. -3 Pa, then argon gas with a purity of not less than 99.99% is introduced to 0.5 atmospheres to ensure that the sample in the furnace cavity is not oxidized during melting. Before the formal melting begins, a pure titanium sample reserved in the melting furnace is melted to absorb residual oxygen in the cavity. After the pure titanium sample cools, if its surface still has a metallic luster, the formal melting begins. During the sample melting process, the sample needs to be repeatedly remelted six times to prevent severe compositional segregation of niobium and molybdenum. After each melting, the sample needs to be flipped before the next melting. The specific parameters and operation of the melting are as follows: the tungsten needle is brought to 1-2 mm above the metal raw material sample, and an arc is started using a current of 60A. After successful arc ignition, the tungsten needle is raised to 3-5 mm above the sample, and then the current is increased to 370A for 3 minutes of melting. The final melting melts the sample into a long strip shape, finally obtaining Nb 45 Ti 40 Mo 10As-cast sample of Cr5 refractory high-entropy alloy.

[0063] For Nb 45 Ti 40 Mo 10 Cr5 refractory high-entropy alloy as-cast samples were wire-cut to obtain 10*10*6mm samples for melting and melting-wear tests and Φ4*6mm samples for compression tests. These samples were then polished with SiC sandpaper of grits of 200, 320, 600, 800, and 1000 grits until the wire-cut marks were removed. The Nb prepared in this invention... 45 Ti 40 Mo 10 Cr5 refractory high-entropy alloy exhibits excellent comprehensive properties, including a compressive fracture strain of 45% at room temperature and a compressive strength of 1.2 GPa (see...). Figure 3 The microhardness at 750℃ is 320 HV.

[0064] The microstructure and XRD diffraction pattern of the high-temperature resistant aluminum melt erosion-wear refractory high-entropy alloy prepared in this embodiment are shown below. Figure 1 and Figure 2 As shown, the microstructure of this refractory high-entropy alloy consists of a single-phase BCC phase with a dendritic morphology. The material exhibits good mechanical properties, including a compressive strength of 1.2 GPa at room temperature, a compressive fracture strain of 45%, and a room temperature hardness of 390 HV. After being etched into molten aluminum at 750℃ for 8 hours, the alloy showed a volume loss of 32.1 mm. 3 Compared to H13 steel (330.3 mm) 3 It decreased by 90.28% ( Figure 17 and Figure 18 The morphology of the aluminum melt erosion interface of this alloy is as follows: Figure 4 As shown, the alloy's erosion products have a relatively uniform composition, and the interface is serrated and wavy. The erosion products are tightly bonded together, effectively preventing the molten aluminum from eroding the alloy matrix and significantly reducing the volume loss of the alloy in the molten aluminum. After 30 minutes of erosion and wear in molten aluminum at 750℃, the volume loss of this alloy was 48.7 mm. 3 Compared to H13 steel (260.1mm) 3 ) decreased by 81.28% ( Figure 18 and Figure 19 ).

[0065] Example 2

[0066] According to Nb 43.2 Ti 38.4 Mo 9.6 Cr 4.8After converting the atomic ratios of each component in the Al4 refractory high-entropy alloy to their mass percentages (wt.%), a total mass of (80±0.1g) of pure metal raw materials was weighed using an analytical balance. The purity of the Ti, 30Ti-70Nb, Cr, 50Ti-50Mo, and Al raw materials used was not less than 99.9%. The weighed mass of Cr and Al was adjusted by an additional 1.5% and 1.0% respectively as burn-off compensation based on the converted mass. The prepared metal raw materials were then placed in a copper mold crucible within a vacuum arc melting furnace. The furnace chamber pressure was evacuated to 5.5×10⁻⁶. -3 Pa, then argon gas with a purity of not less than 99.99% is introduced to 0.5 atmospheres to ensure that the sample in the furnace cavity is not oxidized during melting. Before the formal melting begins, a pure titanium sample reserved in the melting furnace is melted to absorb residual oxygen in the cavity. After the pure titanium sample cools, if its surface still has a metallic luster, the formal melting begins. During the sample melting process, the sample needs to be repeatedly remelted six times to prevent severe compositional segregation of niobium and molybdenum. After each melting, the sample needs to be flipped before the next melting. The specific parameters and operation of the melting are as follows: the tungsten needle is brought to 1-2 mm above the metal raw material sample, and an arc is started using a current of 60A. After successful arc ignition, the tungsten needle is raised to 3-5 mm above the sample, and then the current is increased to 370A for 3 minutes of melting. The final melting melts the sample into a long strip shape, finally obtaining Nb 43.2 Ti 38.4 Mo 9.6 Cr 4.8 As-cast samples of Al4 refractory high-entropy alloy.

[0067] For Nb 43.2 Ti 38.4 Mo 9.6 Cr 4.8 As-cast Al4 refractory high-entropy alloy samples were wire-cut to obtain 10*10*6mm samples for erosion and erosion-wear tests and Φ4*6mm samples for compression tests. These samples were then polished with SiC sandpaper of grits of 200, 320, 600, 800, and 1000 grits until the wire-cut marks were removed. The Nb prepared in this invention... 43.2 Ti 38.4 Mo 9.6 Cr 4.8 Al4 refractory high-entropy alloys exhibit excellent comprehensive properties, including a compressive fracture strain of 50% at room temperature and a compressive strength of 1.3 GPa (see...). Figure 7 The microhardness at 750℃ is 339 HV.

[0068] The microstructure and XRD diffraction pattern of the high-temperature resistant aluminum melt erosion-wear refractory high-entropy alloy prepared in this embodiment are shown below. Figure 5 and Figure 6As shown, the microstructure of this refractory high-entropy alloy consists of a single-phase BCC phase with a dendritic morphology. The material exhibits good mechanical properties, including a compressive strength exceeding 1.2 GPa at room temperature, a compressive fracture strain exceeding 45%, and a room temperature hardness of 400 HV. After being etched into molten aluminum at 750℃ for 8 hours, the alloy showed a volume loss of 18.6 mm². 3 Compared to H13 steel (330.3 mm) 3 ) decreased by 94.37% ( Figure 17 and Figure 18 The morphology of the aluminum melt erosion interface of this alloy is as follows: Figure 8 As shown, the alloy's erosion products have a relatively uniform composition, a slightly smooth interface, and tight bonding between them. This effectively blocks the erosion of the alloy matrix by the molten aluminum, significantly reducing the alloy's volume loss during erosion in the molten aluminum. After 30 minutes of erosion and abrasion in molten aluminum at 750℃, the alloy's volume loss was 27.8 mm. 3 Compared to H13 steel (260.1mm) 3 ) decreased by 89.31% ( Figure 18 and Figure 19 ).

[0069] Example 3

[0070] According to Nb 41.4 Ti 36.8 Mo 9.2 Cr 4.6 After converting the atomic ratios of each component in the Al8 refractory high-entropy alloy to their mass percentages (wt.%), a total mass of (80±0.1g) of pure metal raw materials was weighed using an analytical balance. The purity of the Ti, 30Ti-70Nb, Cr, 50Ti-50Mo, and Al raw materials used was not less than 99.9%. The weighed mass of Cr and Al was adjusted by an additional 1.5% and 1% respectively as burn-off compensation based on the converted mass. The prepared metal raw materials were then placed in a copper mold crucible within a vacuum arc melting furnace. The furnace chamber pressure was evacuated to 5.5×10⁻⁶. -3Pa, then argon gas with a purity of not less than 99.99% is introduced to 0.5 atmospheres to ensure that the sample in the furnace cavity is not oxidized during melting. Before the formal melting begins, a pure titanium sample reserved in the melting furnace is melted to absorb residual oxygen in the cavity. After the pure titanium sample cools, if its surface still has a metallic luster, the formal melting begins. During the sample melting process, the sample needs to be repeatedly remelted six times to prevent severe compositional segregation of niobium and molybdenum. After each melting, the sample needs to be flipped before the next melting. The specific parameters and operation of the melting are as follows: the tungsten needle is brought to 1-2 mm above the metal raw material sample, and an arc is started using a current of 60A. After successful arc ignition, the tungsten needle is raised to 3-5 mm above the sample, and then the current is increased to 370A for 3 minutes of melting. The final melting melts the sample into a long strip shape, finally obtaining Nb 41.4 Ti 36.8 Mo 9.2 Cr 4.6 As-cast sample of Al8 refractory high-entropy alloy.

[0071] For Nb 41.4 Ti 36.8 Mo 9.2 Cr 4.6 As-cast samples of Al8 refractory high-entropy alloy were wire-cut to obtain 10*10*6mm samples for melting and erosion-wear tests and Φ4*6mm samples for compression tests. These samples were then polished with SiC sandpaper of grits 200, 320, 600, 800, and 1000 grits until the wire-cut marks were removed. The Ti-Nb-Cr-Mo-Al refractory high-entropy alloy prepared in this invention exhibits excellent comprehensive properties, with a compressive fracture strain of 80% at room temperature and a compressive strength of 1.6 GPa (see...). Figure 11 The microhardness at 750℃ is 370 HV.

[0072] The microstructure and XRD diffraction pattern of the high-temperature resistant aluminum melt erosion-wear refractory high-entropy alloy prepared in this embodiment are shown below. Figure 9 and Figure 10 As shown, the microstructure of this refractory high-entropy alloy consists of a single-phase BCC phase with a dendritic morphology. The material exhibits good mechanical properties, including a compressive strength exceeding 1.3 GPa at room temperature, a compressive fracture strain exceeding 50%, and a room temperature hardness of 425 HV. After being etched into molten aluminum at 750℃ for 8 hours, the alloy showed a volume loss of 3.9 mm. 3 Compared to H13 steel (330.3 mm) 3 ) decreased by 98.82% ( Figure 17 and Figure 18 The morphology of the aluminum melt erosion interface of this alloy is as follows: Figure 12As shown, the alloy's erosion products have a relatively uniform composition, are tightly bonded, and have a fairly smooth interface. This effectively blocks the erosion of the alloy matrix by the molten aluminum, significantly reducing the volume loss of the alloy in the molten aluminum. After 30 minutes of erosion and wear in molten aluminum at 750℃, the volume loss of this alloy was 11.3 mm. 3 Compared to H13 steel (260.1mm) 3 ) decreased by 95.66% ( Figure 18 and Figure 19 ).

[0073] Example 4

[0074] According to Nb 40.5 Ti 36 Mo9Cr 4.5 Al 10 After converting the atomic ratios of each component in the refractory high-entropy alloy to their mass percentages (wt.%), a total mass of (80±0.1g) of pure metal raw materials was weighed using an analytical balance. The purity of the Ti, 30Ti-70Nb, Cr, 50Ti-50Mo, and Al raw materials used was not less than 99.9%. The weighed mass of Cr and Al was adjusted by 1.5% and 1% respectively as compensation for burn-off. The prepared metal raw materials were then placed in a copper mold crucible in a vacuum arc melting furnace. The furnace chamber pressure was evacuated to 5.5×10⁻⁶. -3 Pa, then argon gas with a purity of not less than 99.99% is introduced to 0.5 atmospheres to ensure that the sample in the furnace cavity is not oxidized during melting. Before the formal melting begins, a pure titanium sample reserved in the melting furnace is melted to absorb residual oxygen in the cavity. After the pure titanium sample cools, if its surface still has a metallic luster, the formal melting begins. During the sample melting process, the sample needs to be repeatedly remelted six times to prevent severe compositional segregation of niobium and molybdenum. After each melting, the sample needs to be flipped before the next melting. The specific parameters and operation of the melting are as follows: the tungsten needle is brought to 1-2 mm above the metal raw material sample, and an arc is started using a current of 60A. After successful arc ignition, the tungsten needle is raised to 3-5 mm above the sample, and then the current is increased to 370A for 3 minutes of melting. The final melting melts the sample into a long strip shape, finally obtaining Nb 40.5 Ti 36 Mo9Cr 4.5 Al 10 As-cast sample of refractory high-entropy alloy.

[0075] For Nb 40.5 Ti 36 Mo9Cr 4.5 Al 10Refractory high-entropy alloy as-cast samples were wire-cut to obtain 10*10*6mm samples for melting and erosion-wear tests and Φ4*6mm samples for compression tests. These samples were then polished with SiC sandpaper of grits 200, 320, 600, 800, and 1000 grits until the wire-cut marks were removed. The Ti-Nb-Cr-Mo-Al refractory high-entropy alloy prepared in this invention exhibits excellent comprehensive properties, with a compressive fracture strain of 47% at room temperature and a compressive strength of 1.68 GPa (see...). Figure 15 The microhardness at 750℃ is 380 HV.

[0076] The microstructure and XRD diffraction pattern of the high-temperature resistant aluminum melt erosion-wear refractory high-entropy alloy prepared in this embodiment are shown below. Figure 13 and Figure 14 As shown, the microstructure of this refractory high-entropy alloy consists of a single-phase BCC phase with a dendritic morphology. The material exhibits good mechanical properties, including a compressive strength exceeding 1.6 GPa at room temperature, a compressive fracture strain exceeding 45%, and a room temperature hardness of 440 HV. After being etched into molten aluminum at 750℃ for 8 hours, the alloy showed a volume loss of 10.6 mm². 3 Compared to H13 steel (330.3 mm) 3 ) decreased by 96.79% ( Figure 17 and Figure 18 The morphology of the aluminum melt erosion interface of this alloy is as follows: Figure 16 As shown, the alloy's erosion products have a relatively uniform composition and are tightly bonded together. However, microcracks exist at the bonding interfaces, but these cracks still effectively prevent the molten aluminum from eroding the alloy matrix, significantly reducing the alloy's volume loss in the molten aluminum. After 30 minutes of erosion and wear in molten aluminum at 750℃, the alloy's volume loss was 20.1 mm. 3 Compared to H13 steel (260.1mm) 3 It decreased by 92.27% ( Figure 18 and Figure 19 Example 4 shows a decrease in resistance to molten aluminum corrosion compared to Example 3. This is because the increased Al content to 10 at.% makes the alloy more brittle, resulting in more brittle reaction products that are prone to microcracks. However, its resistance to molten aluminum corrosion is still significantly improved compared to H13 steel.

[0077] Figure 17-19 In this context, samples R1-R4 contain components from Examples 1-4, respectively. Figure 17-19 It can be seen that the high-temperature resistant aluminum melt erosion and erosion-wear refractory high-entropy alloy of the present invention has significantly better high-temperature resistant aluminum melt erosion and erosion-wear performance than H13 steel; the performance is further improved after adding aluminum (Al), and the performance is even better at the appropriate aluminum content (the performance of Example 3 is the best).

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A refractory high-entropy alloy resistant to high-temperature molten aluminum erosion and erosion-wear, characterized in that: Based on atomic percentage, its composition is: 40-50 at.% Nb, 35-40 at.% Ti, 4-10 at.% Mo, 4-5 at.% Cr, and no more than 10 at.% Al.

2. The refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear according to claim 1, characterized in that: Based on atomic percentage, its composition is: 40.5-45 at.% Nb, 36-40 at.% Ti, 9-10 at.% Mo, 4.5-5 at.% Cr, and no more than 10 at.% Al.

3. The refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear according to claim 1, characterized in that: Based on atomic percentage, its composition is: 40.5-45 at.% Nb, 36-40 at.% Ti, 9-10 at.% Mo, 4.5-5 at.% Cr, and 4-10 at.% Al.

4. The refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear according to claim 1, characterized in that, The refractory high-entropy alloy that is resistant to high-temperature aluminum melt erosion and erosion-wear has a body-centered cubic crystal structure at room temperature, a compressive strength greater than or equal to 1 GPa, and a compressive fracture strain greater than or equal to 45%.

5. The refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear according to claim 1, characterized in that, The volume loss after 8 hours of molten aluminum at 750℃ does not exceed 7.5 vol.%, and the volume loss after molten aluminum at 750℃ followed by abrasion does not exceed 9.2 vol.%.

6. The method for preparing the refractory high-entropy alloy resistant to high-temperature aluminum melt erosion and erosion-wear as described in any one of claims 1-5, characterized in that, Includes the following steps: The raw materials of refractory high-entropy alloys are mixed and smelted under a protective atmosphere to obtain refractory high-entropy alloys that are resistant to high-temperature aluminum melt erosion and erosion-wear.

7. The preparation method according to claim 6, characterized in that, The number of smelting processes is 5 or more; The melting is either vacuum induction melting or vacuum arc melting; The protective atmosphere is argon; the pressure of the protective atmosphere is 0.5-1 atmosphere; the protective atmosphere is first evacuated to 1×10⁻⁶. -2 The solution is obtained by filling with a protective gas at a pressure below 1 Pa.

8. The preparation method according to claim 7, characterized in that, The vacuum arc melting current is 300-400A, and the melting time is 1-3 minutes.

9. The preparation method according to claim 6, characterized in that, The raw material for the refractory high-entropy alloy is a metallic element or an intermediate alloy; the purity of the metallic element or intermediate alloy is not less than 99.9%. The metallic element is Ti, Cr, or Al; The intermediate alloys are Ti-Nb and Ti-Mo.

10. The application of the refractory high-entropy alloy according to any one of claims 1-5 in the preparation of molds, crucibles, nozzles, and stirring rods resistant to high-temperature aluminum melt erosion and erosion-wear.

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