Ultrahigh-temperature ablation resistant refractory high-entropy alloy copper infiltration composite material and preparation method thereof

Abstract

The invention discloses an ultrahigh-temperature ablation resistant refractory high-entropy alloy copper infiltrated composite material and a preparation method of the ultrahigh-temperature ablation resistant refractory high-entropy alloy copper infiltrated composite material. The composite material comprises a high-entropy alloy framework and a copper phase penetrating into pores of the high-entropy alloy framework, the pores of the high-entropy alloy framework are filled with the copper phase through capillary force capillary penetration, and the copper phase interacts with the framework to achieve ablation resistance. The composite material breaks through the performance bottlenecks of a traditional tungsten infiltrated copper material in the aspects of high density, large ablation rate and the like, technical innovation of a light-weight, long-life and high-reliability thermal protection material is achieved, and a key material support is provided for a next-generation high-performance aerospace propulsion system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of light-weight high-temperature-resistant high-entropy alloy materials, and relates to an ultra-high-temperature-ablation-resistant refractory high-entropy alloy copper-infiltrated composite material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of aerospace technology, human space exploration activities (such as moon landing, Mars exploration and deep space missions) have higher requirements for the carrying capacity of rocket engines. As the core component of the solid rocket engine nozzle, the throat liner needs to serve in extreme working conditions: the working temperature is higher than 3000℃, and at the same time, it is subjected to the erosion of high-speed (>1000m / s) gas flow containing solid particles, facing multiple damages such as thermal-chemical ablation, mechanical ablation and particle erosion. In addition, the surface temperature of the throat liner rises sharply (>2000℃) when the engine starts, causing severe thermal shock. If the material is insufficient in ablation resistance and thermal shock resistance, the throat liner will deform, directly affecting the thrust and efficiency of the engine.

[0003] At present, the throat liner material generally uses tungsten copper (W-Cu) alloy. This material relies on the "sweating cooling" mechanism of the copper phase to achieve ablation resistance protection: copper melts and evaporates at high temperatures to take away heat and form a protective gas film. However, tungsten copper has two problems: high density and insufficient ablation resistance. First, the density is as high as 16g / cm³ or more, which will significantly increase the weight of the spacecraft structure and restrict the improvement of the carrying efficiency. Second, the ablation rate is high under the erosion of ultra-high temperature gas, which makes it difficult to meet the long-term reliable service requirements.

[0004] To break through the above bottleneck, new light-weight high-temperature-resistant materials have become the focus of research. Refractory high-entropy alloys are composed of five or more equal atomic ratio or near equal atomic ratio refractory metals, and have four characteristics brought by high-entropy effect: (1) delayed diffusion effect: inhibits atomic diffusion, improves high-temperature structural stability; (2) lattice distortion effect: enhances solid solution strengthening effect, maintains high-temperature strength; (3) high-entropy stable phase: single-phase solid solution structure avoids brittle phase precipitation; (4) low density advantage: the density is reduced by 30%~50% compared with tungsten alloy.

[0005] Although refractory high-entropy alloys have significant potential in high-temperature mechanical properties and lightweight, their pure alloy form still has problems of insufficient oxidation resistance and limited ablation resistance. Therefore, further optimizing the performance through composite design (such as introducing low-melting-point metal phase) has become a key direction. For example, although ultra-high-temperature ceramic modified C / C composite materials have been applied to the thermal protection components (such as nose cone, wing leading edge) of hypersonic aircraft, they are still insufficient in the strong oxidation and ablation environment of solid rocket engines.

[0006] In summary, there is an urgent need to develop a new type of throat liner material that has low density, excellent ablation resistance, thermal shock resistance and high-temperature mechanical properties, to replace the traditional tungsten copper alloy and meet the stringent requirements of the next generation of aerospace power systems. SUMMARY

[0007] In order to overcome the above problems, the present application provides a superhigh-temperature-ablation-resistant refractory high-entropy alloy copper-infiltrated composite material and a preparation method thereof. The composite material comprises a high-entropy alloy framework and a copper phase infiltrated into the pores thereof, the copper phase is filled into the pores of the high-entropy alloy framework through capillary infiltration, and the copper phase interacts with the framework to achieve ablation resistance. The composite material breaks through the performance bottleneck of traditional tungsten copper-infiltrated materials in terms of high density and large ablation rate, realizes the technological innovation of lightweight, long-life and high-reliability thermal protection materials, and provides key material support for the next generation of high-performance aerospace propulsion systems.

[0008] Specifically, the present application aims to provide the following aspects:

[0009] In a first aspect, a composite material is provided, which comprises a high-entropy alloy framework and a copper phase infiltrated into the pores thereof, and the copper phase is filled into the pores of the high-entropy alloy framework through capillary infiltration, and the copper phase interacts with the framework to achieve ablation resistance.

[0010] Optionally, the composition of the high-entropy alloy framework is expressed as WMoTaNbX, X is any one of Ti, V, Zr, and Hf.

[0011] Optionally, the composition of the high-entropy alloy framework is expressed as WMoTaNbX1X2, X1 and X2 are each independently selected from any one of Ti, V, Zr, and Hf, and X1 is different from X2.

[0012] Optionally, the porosity of the high-entropy alloy framework is 10% to 15%.

[0013] Optionally, in the composite material, the content of the copper phase is 5 to 10 wt.%.

[0014] Optionally, the linear ablation rate of the composite material is 5 to 6 μm / s.

[0015] In a second aspect, a method for preparing the composite material of the first aspect is provided, which comprises:

[0016] Step 1: melting elemental substances comprising W, Mo, Ta, and Nb into a high-entropy alloy ingot;

[0017] Step 2: pressing the high-entropy alloy ingot into a green body;

[0018] Step 3: sintering the green body to obtain a high-entropy alloy framework;

[0019] Step 4: infiltrating copper in the high-entropy alloy framework to obtain the composite material.

[0020] In step 1, the elemental substance further includes any one or two of Ti, V, Zr, and Hf.

[0021] Optionally, step 2 includes:

[0022] Step 2-1: The high-entropy alloy ingot is crushed into powder using the plasma rotating electrode method;

[0023] Step 2-2: Mix the powder with the forming agent to form a slurry;

[0024] Steps 2-3 involve drying the slurry and pressing it into a green body.

[0025] In step 2-2, the forming agent is stearic acid.

[0026] The beneficial effects of this invention include:

[0027] (1) The composite material provided by the present invention uses a low-density high-entropy alloy as a skeleton, and the copper phase penetrates into the pores of the skeleton through capillary penetration, interacting with the skeleton to achieve ablation resistance. The composite material significantly reduces the structural weight of hot-end components such as the nozzle throat liner of rocket engines, which is beneficial to improving the thrust-to-weight ratio and payload capacity of spacecraft.

[0028] (2) The composite material method provided by the present invention achieves comprehensive high-quality performance in terms of ablation resistance, lightweight, high-temperature mechanical properties and oxidation resistance by optimizing the composition and process parameters. At the same time, its preparation process is mature, the cost is controllable, and it is suitable for large-scale application. Attached Figure Description

[0029] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0030] In the attached diagram:

[0031] Figure 1 A macroscopic photograph of the high-entropy alloy prepared in Example 1 is shown;

[0032] Figure 2 The surface SEM image of the high-entropy alloy prepared in Example 1 is shown;

[0033] Figure 3 A macroscopic photograph of the high-entropy alloy skeleton prepared according to Counterexample 1 is shown;

[0034] Figure 4A macroscopic photograph of the high-entropy alloy prepared in Comparative Example 1 is shown.

[0035] Figure 5 The surface SEM image of the high-entropy alloy prepared in Comparative Example 1 is shown. Detailed Implementation

[0036] The following will refer to the appendix. Figures 1 to 5 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0037] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0038] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0040] On the one hand, according to the present invention, a copper-infiltrated composite material of a refractory high-entropy alloy resistant to ultra-high temperature ablation is provided. The composite material includes a high-entropy alloy skeleton and a copper phase infiltrating into its pores. The copper phase fills the pores of the high-entropy alloy skeleton through capillary infiltration and interacts with the skeleton to achieve ablation resistance.

[0041] In this invention, the copper phase and metallurgical bonding are achieved through the lattice distortion effect of the high-entropy alloy skeleton and the interface regulation of Cu elements, breaking through the technical bottleneck of traditional copper-infiltrating materials. Under ultra-high temperature ablation environment, the copper phase escapes directionally through the pores, reducing the linear ablation rate by 65%~70% compared to traditional tungsten-infiltrating copper materials. At the same time, the nanocrystalline structure of the high-entropy skeleton and the toughening effect of the copper phase work synergistically, enabling the composite material to possess both high-temperature strength and fracture toughness, providing a lightweight and long-life solution for spacecraft thermal protection systems.

[0042] In one embodiment, the composition expression of the high-entropy alloy skeleton is WMoTaNbX, where X is any one of Ti, V, Zr, and Hf, and the atomic ratio of W, Mo, Ta, Nb, and X is 20 at.%.

[0043] In one embodiment, the composition expression of the high-entropy alloy skeleton is WMoTaNbX1X2, where X1 and X2 are each independently selected from any one of Ti, V, Zr, and Hf, and X1 is different from X2. In this case, the atomic ratio of W, Mo, Ta, Nb, X1, and X2 is 16.67 at.

[0044] In this invention, the main components W, Mo, Ta, and Nb all possess ultra-high melting points (>2400℃), providing a fundamental guarantee for resistance to ultra-high temperature ablation. W has the highest melting point, serving as the framework matrix; W forms a continuous solid solution with Mo, suppressing high-temperature embrittlement; Ta enhances oxidation resistance and inhibits high-temperature grain boundary slip; Nb reduces density, achieving lightweighting. The quaternary combination forms an ultra-high melting point BCC solid solution, meeting the requirements for resistance to ultra-high temperature ablation. Furthermore, Ti, V, Zr, and Hf enhance capillary penetration, especially V.

[0045] In this invention, the porosity of the high-entropy alloy skeleton is 10%~15%.

[0046] In this invention, the copper phase content is 5~10 wt.%, for example, 7 wt.%. The constraint for selecting this parameter is that when the copper content is <5 wt.%, the copper content is too low, there is no "sweating effect," the sample surface temperature cannot be effectively reduced, and the sample linear ablation rate is high. When the copper content is greater than 10 wt%, due to the excessively high porosity of the framework, after copper volatilizes during the ablation process, the framework strength is low, making it prone to spalling, resulting in poor ablation resistance.

[0047] In this invention, the density of the composite material is 98.5-99%; the linear ablation rate is 5-6 μm / s.

[0048] In one embodiment, the composite material has a density of 98.8% and a linear ablation rate of 5.2 μm / s.

[0049] On the other hand, according to the method for preparing the composite material according to the first aspect of the present invention, the method includes:

[0050] Step 1: Melt elemental materials including W, Mo, Ta and Nb into high-entropy alloy ingots;

[0051] Step 2: Press the high-entropy alloy ingot into a green billet;

[0052] Step 3: Sinter the green blank to obtain a high-entropy alloy skeleton;

[0053] Step 4: Infiltrate copper into the high-entropy alloy skeleton to obtain the composite material.

[0054] Specifically:

[0055] In step 1, elemental substances including W, Mo, Ta, and Nb are weighed and high-entropy alloy ingots are prepared by vacuum induction levitation melting.

[0056] In one embodiment, the weighed elemental substance further includes any one or two of Ti, V, Zr, and Hf, and the elements satisfy an equiatomic ratio.

[0057] In step 1, the purity of the element is ≥99.99% to avoid impurity elements such as O, C, and S inducing the precipitation of brittle phases, which would affect the high-temperature mechanical properties and ablation stability of the prepared composite material.

[0058] In step 1, before melting, a vacuum of 5×10⁻⁶ is first applied. -3 Pa ~6×10 -3 Pa, then fill with an inert gas such as argon to 0.04~0.06 MPa. For example, first evacuate to 5×10 Pa. -3 Pa, then fill with argon gas to 0.05 MPa.

[0059] In this invention, a vacuum is first drawn to 5×10⁻⁶. -3 Pa ~6×10 -3 Pa is used to completely eliminate impurities such as oxygen and water, avoiding high-entropy alloy skeleton oxidation at high temperatures; then an inert gas such as argon is introduced to 0.04~0.06 MPa to suppress element volatilization.

[0060] In step 1, the melting temperature is 3300~3600℃, for example, 3500℃. The constraints for selecting this parameter are: this temperature range is sufficient to completely melt the refractory metals W, Mo, Ta, and Nb and achieve atomic-scale homogeneous mixing to form a stable BCC solid solution structure; if the temperature is below 3300℃, W and Ta are difficult to completely melt, resulting in uneven composition; if the temperature is above 3600℃, the risk of reaction between the crucible material and the melt will increase, and the energy consumption will be too high, making it unfeasible for industrial use.

[0061] In step 1, the melting and holding time is 8-12 minutes, for example, 10 minutes. The constraint for selecting this parameter is that this holding time ensures sufficient diffusion of the main components, homogenization of the melt, and elimination of microsegregation. Too short a time (<8 minutes) will lead to uneven element distribution, affecting the subsequent sintering density and mechanical properties; too long a time (>12 minutes) may cause local overheating or element volatilization, which will reduce the density and mechanical properties of the resulting composite material.

[0062] In step 1, to improve the compositional uniformity of the high-entropy alloy ingot and eliminate dendritic segregation, it is preferable to perform 3 to 5 repeated melting processes, for example, 4 times. After each melting process, the high-entropy alloy ingot is flipped and remelted to promote the uniform mixing of the multiphase system. Multiple melting processes significantly improve the microstructure consistency of the high-entropy alloy and reduce the tendency for the formation of brittle intermetallic compounds.

[0063] In one embodiment, step 2 includes:

[0064] Step 2-1: The high-entropy alloy ingot is crushed into powder using the plasma rotating electrode method;

[0065] Step 2-2: Mix the powder with the forming agent to form a slurry;

[0066] Steps 2-3 involve drying the slurry and pressing it into a green body.

[0067] In step 2-1, the high-entropy alloy ingot is processed into a regular shape, such as a rod, to fit the clamping system of the plasma rotating electrode method equipment, ensuring dynamic balance stability during high-speed rotation and avoiding equipment damage or uneven powder particle size caused by vibration.

[0068] In step 2-1, the plasma rotating electrode method utilizes a plasma arc as a heat source to locally melt the high-entropy alloy ingot. As the high-entropy alloy ingot rotates, centrifugal force causes the molten metal to be ejected from the end face, rapidly solidifying in a cooling atmosphere to form spherical or near-spherical powder particles. This method eliminates the need for a crucible, avoiding contamination, and produces powders with high sphericity and good flowability, suitable for subsequent pressing and sintering.

[0069] Furthermore, the rotation speed is 15,000~25,000 rpm, for example, 20,000 rpm. The constraint for choosing this parameter is that the rotation speed directly affects the magnitude of the centrifugal force, thus determining the powder particle size. When the rotation speed is too low (<15,000 rpm), the average particle size of the resulting powder exceeds 40 μm, which is not conducive to dense sintering; when the rotation speed is too high (>25,000 rpm), it may lead to the fracture of high-entropy alloy ingots or instability of the plasma arc, affecting production safety and powder yield. A rotation speed of 15,000~25,000 rpm is preferred to obtain the optimal particle size distribution while ensuring safe operation.

[0070] Furthermore, the plasma rotating electrode method is carried out in an inert gas such as argon to avoid the formation of brittle oxide inclusions and ensure powder purity and subsequent sintering performance.

[0071] In step 2-1, the obtained particle size distribution is 15~53μm, and the average particle size (D50) of the powder is 20~40μm, such as D50 being 30μm. The aforementioned rotation speed is also one of the important ways to obtain this particle size. Spherical powder of this particle size is beneficial for forming a uniformly pressed green body.

[0072] In step 2-2, the powder is passed through a 200-mesh sieve to remove agglomerated particles, ensuring uniform particle size distribution and improving the consistency of subsequent mixing and pressing.

[0073] In step 2-2, the forming agent is stearic acid. This forming agent has good lubricity and adhesion, reduces the friction between particles and between particles and the mold during the pressing process, prevents cracking and delamination, and improves the strength of the green body; in particular, it is preferred due to its moderate decomposition temperature, low residue, and low cost.

[0074] Furthermore, the mass of the forming agent is 1 to 2 wt.% of the powder mass, for example, 1.5 wt.%. The constraint for selecting this parameter is that when the mass of the forming agent is less than 1 wt.%, compression cracking is likely to occur; when it is more than 2 wt.%, pore and blistering defects will be caused.

[0075] In one embodiment, the powder is preheated for 20-30 minutes, the forming agent is prepared into a 1-3 wt.% solution, and then the solution is added to the preheated powder (powder to solution mass ratio of (4-6):1) to obtain a slurry. Most preferably, the powder is preheated for 30 minutes, the forming agent is prepared into a 2 wt.% solution with alcohol, and then the solution is added to the preheated powder (powder to solution mass ratio of 5:1) to obtain a slurry.

[0076] Preheating removes trace amounts of water from the powder and increases its temperature, enhancing its wettability with the forming agent solution and preventing localized clumping. The powder-to-solution mass ratio is (4~6):1, ensuring the solution fully wets the powder surface without causing over-wetting and affecting the uniformity of the forming agent distribution.

[0077] In steps 2-3, the drying temperature is 50~70℃, for example 60℃; the drying time is 1~3h, for example 2h. The constraints for selecting these parameters are: this temperature prevents powder oxidation and avoids premature melting of the forming agent, which could lead to powder sticking. Too short a drying time will result in solvent residue, affecting pressing performance.

[0078] In steps 2-3, the pressing pressure is 150~500 MPa, with 350 MPa being the optimal value. The constraint for selecting this parameter is that the pressing pressure directly affects the quality of the green body. If the pressure is too low (<150 MPa), the particles are not firmly bonded, resulting in low green body strength and easy breakage; if the pressure is too high (>500 MPa), it will lead to particle breakage, excessive densification, a significant reduction in porosity, or even pore closure, severely affecting the capillary permeation ability of the subsequent copper phase. 150~300 MPa is the preferred range, ensuring both green body strength and maintaining a target porosity of 10%~15%, which facilitates uniform permeation of molten copper along the connected pores.

[0079] In steps 2-3, the holding time for pressing is 4-8 minutes, for example, 5 minutes. The constraint for selecting this parameter is that too short a holding time can easily lead to cracking during subsequent sintering; too long a holding time will not significantly improve the situation and will reduce efficiency.

[0080] In step 3, the sintering includes:

[0081] First stage: In a vacuum, the temperature is increased from room temperature to 300-400℃ at a heating rate of 80-100℃ / min, held for 5-15 minutes, and then allowed to cool naturally to room temperature;

[0082] Second stage: Under hydrogen protection, the temperature is increased from room temperature to 1800-2200℃ at a heating rate of 80-120℃ / min, held for 20-30 minutes, and then cooled to room temperature with the furnace.

[0083] The first stage is a low-temperature pre-degreasing stage, the main purpose of which is to completely remove forming agents such as stearic acid added to the green billet, preventing them from decomposing in the second stage and generating large amounts of gases such as CO2, H2O, and hydrocarbons, which could cause blistering, cracking, carbon residue, or internal defects. The second stage achieves metallurgical bonding between particles at high temperatures, forming a porous framework with sufficient mechanical strength and a stable pore structure to support the subsequent copper infiltration process and withstand ultra-high temperature service loads.

[0084] In the first stage, a vacuum environment prevents highly reactive metals such as W, Mo, and Ta from oxidizing or forming volatile oxides at high temperatures, with a vacuum level of 4~10 Pa. A heating rate of 80~100℃ / min significantly shortens the degreasing cycle while ensuring orderly gas release. The temperature range of 300~400℃ is used because degreasing is incomplete below 300℃, while above 400℃ it may prematurely activate metal diffusion, leading to pore closure and affecting the interconnected pore structure required for subsequent copper penetration. A holding time of 5~15 min helps decomposition products to fully diffuse out of the green body, ensuring uniform degreasing.

[0085] In the second stage, after degreasing, the green blank is free of organic interference, allowing for a faster heating rate of 80-120℃ / min. This rate inhibits excessive grain growth and reduces the risk of thermal stress cracking caused by internal and external temperature differences. The second stage is conducted in hydrogen, achieving efficient reduction of oxides on the surface of high-entropy alloy powder, significant improvement in sintering activity, and synergistic removal of residual carbon. A sintering temperature of 1800-2200℃ is sufficient to activate atomic diffusion, promote particle growth and pore shrinkage, and achieve densification. Below 1800℃, the diffusion driving force is insufficient, resulting in low skeleton strength. Above 2200℃, abnormal grain growth or local melting is likely to occur, disrupting pore connectivity. The optimal temperature range of 1800-2200℃ is chosen to maintain a target porosity of 10%-15% while ensuring strength. A holding time of 20-30 minutes is sufficient to complete the densification process. Final furnace cooling avoids residual stress or microcracks caused by differences in thermal expansion coefficients, ensuring skeleton integrity and dimensional stability.

[0086] In step 3, the sintering process is controlled in stages: the first stage involves vacuum degreasing to remove the forming agent, and the second stage involves solid-state sintering to build a high-strength porous framework. This achieves a synergistic optimization of high structural stability and controllable porosity (10%~15%) in the high-entropy alloy framework. This process not only avoids carbon contamination and structural defects but also provides a pore network for the subsequent capillary infiltration of the copper phase, making it a key step in the preparation of the composite material.

[0087] In one embodiment, the sintering includes:

[0088] First stage: Under 8 Pa, the temperature is increased from room temperature to 400℃ at a heating rate of 80℃ / min, held for 10 minutes, and then naturally cooled to room temperature;

[0089] Second stage: Under hydrogen protection, the temperature is increased from room temperature to 2000℃ at a rate of 100℃ / min, and held for 20 minutes.

[0090] In step 3, a high-entropy alloy skeleton with a porosity of 10%~15% is obtained.

[0091] In one embodiment, step 4 includes: placing a pure copper sheet under a high-entropy alloy skeleton, heating it from room temperature to 1100-1400°C at a heating rate of 5-20°C / min in a hydrogen atmosphere, holding it at that temperature for 20-40 minutes, cooling it to room temperature in the furnace, and removing residual copper from the surface to obtain the composite material. Preferably, the temperature is increased from room temperature to 1350°C at a heating rate of 10°C / min in a hydrogen atmosphere, held at that temperature for 30 minutes, cooled to room temperature in the furnace, and residual copper is removed to obtain the composite material.

[0092] In step 4, a pressureless melting and infiltration method with a "bottom-placed copper source" is adopted, utilizing the combined effect of gravity and capillary force to achieve the infiltration of molten copper into the porous framework from bottom to top. Specifically, after the copper melts, significant capillary forces are generated in the open pores of the high-entropy alloy framework, driving the liquid copper to infiltrate upwards along the pores.

[0093] Furthermore, trace oxides that may exist on the surface of the high-entropy alloy framework are reduced by hydrogen gas, which improves the wettability of the molten copper and the framework, promoting metallurgical bonding. A heating rate of 5–20 °C / min promotes copper infiltration. A temperature range of 1100–1400 °C ensures complete melting of the copper and sufficient fluidity, while preventing excessive densification of the framework due to excessive heat. A holding time of 20–40 min allows the molten copper to fully fill the pores of the framework through capillary action, achieving deep and uniform penetration.

[0094] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0095] Example 1

[0096] (1) Place W, Mo, Ta, Nb, and V (W 30.4 wt.%, Mo 15.9 wt.%, Ta 29.9 wt.%, Nb 15.4 wt.%, V 8.4 wt.%) with each element having a purity ≥ 99.99% and an equiatomic ratio in a vacuum induction levitation furnace, and evacuate the furnace to 5 × 10⁻⁶. -3 Pa, then fill with argon gas to 0.05 MPa, and melt at 3500℃ 4 times, holding for 10 minutes each time. After the last melting is completed and cooled, a high-entropy alloy ingot is obtained.

[0097] (2) The high-entropy alloy ingot is cut into cylindrical rods with a diameter of 50mm×100mm by wire cutting. The spherical powder with a particle size distribution of 15~53μm and an average particle size (D50) of 30μm is obtained by plasma rotating electrode method (rotation speed 20000rpm, argon protection).

[0098] The powder is passed through a 200-mesh sieve, and stearic acid is weighed at 1.5 wt.% of the powder mass. The stearic acid is dissolved in anhydrous ethanol at 60°C to obtain a solution with a stearic acid content of 2 wt.%. The powder is poured into a stainless steel container and heated and stirred in a water bath at 60°C for 30 minutes. The powder and the solution are mixed at a mass ratio of 5:1 to obtain a slurry.

[0099] The slurry was dried in a vacuum oven at 60°C for 2 hours, then loaded into a chrome steel mold and pressed using a universal testing machine. The pressing pressure was 150 MPa and the holding time was 5 minutes to obtain a Φ20×10mm green embryo.

[0100] (3) The green billet is placed in a vacuum sintering furnace and heated from 25°C to 300°C at a heating rate of 80°C / min under a vacuum of 10Pa. The temperature is held for 10 minutes and then naturally cooled to room temperature. Then, under hydrogen protection, the temperature is heated from room temperature to 1800°C at a heating rate of 100°C / min and held for 20 minutes. The high-entropy alloy skeleton with a porosity of 12% is obtained by furnace cooling.

[0101] (4) Place an electrolytic copper sheet with a purity of 99.99% under a high-entropy alloy skeleton, and heat it from room temperature to 1100℃ in a hydrogen atmosphere at a heating rate of 10℃ / min. Hold it at that temperature for 20min, and then cool it to room temperature in the furnace. Remove the remaining copper by machining to obtain a WMoTaNbV copper-infiltrated composite material with a density of 98.5% and a Cu content of 5wt.%.

[0102] (5) The obtained WMoTaNbV copper-infiltrated composite material has a linear ablation rate of 5.4 μm / s, a compressive strength of 2200 MPa, and a fracture toughness of 16 MPa·m. 1 / 2 .

[0103] Example 2

[0104] (1) Place W, Mo, Ta, Nb, and V (W 30.4 wt.%, Mo 15.9 wt.%, Ta 29.9 wt.%, Nb 15.4 wt.%, V 8.4 wt.%) with each element having a purity ≥ 99.99% and an equiatomic ratio in a vacuum induction levitation furnace, and evacuate the furnace to 5 × 10⁻⁶. -3 Pa, then fill with argon gas to 0.05 MPa, and melt at 3500℃ 4 times, holding for 10 minutes each time. After the last melting is completed and cooled, a high-entropy alloy ingot is obtained.

[0105] (2) The high-entropy alloy ingot is cut into cylindrical rods with a diameter of 50mm×100mm by wire cutting. The spherical powder with a particle size distribution of 15~53μm and an average particle size (D50) of 30μm is obtained by plasma rotating electrode method (rotation speed 20000rpm, argon protection).

[0106] The powder is passed through a 200-mesh sieve, and stearic acid is weighed at 1.5 wt.% of the powder mass. The stearic acid is dissolved in anhydrous ethanol at 60°C to obtain a solution with a stearic acid content of 2 wt.%. The powder is poured into a stainless steel container and heated and stirred in a water bath at 60°C for 30 minutes. The powder and the solution are mixed at a mass ratio of 5:1 to obtain a slurry.

[0107] The slurry was dried in a vacuum oven at 60℃ for 2 hours, then placed into a chrome steel mold and pressed using a universal testing machine. The pressing pressure was 350MPa and the holding time was 5 minutes to obtain a Φ20×10mm green embryo.

[0108] (3) The green billet is placed in a vacuum sintering furnace and heated from 25°C to 400°C at a heating rate of 80°C / min under a vacuum of 8Pa. It is held for 10 minutes and then cooled to room temperature naturally. Then, under hydrogen protection, it is heated from room temperature to 2000°C at a heating rate of 100°C / min and held for 20 minutes. It is then cooled with the furnace to obtain a high-entropy alloy skeleton with a porosity of 15%.

[0109] Figure 1 Macroscopic photographs of the prepared high-entropy alloy skeleton are shown. It can be seen that the prepared refractory high-entropy alloy skeleton is a regular cylindrical shape with no obvious macroscopic cracks, fractures or other defects on the surface. The overall structure is complete and the macroscopic bonding state is uniform. This indicates that the forming and sintering processes during the preparation process effectively ensured the formability and integrity of the alloy skeleton, providing a structural stability basis for subsequent performance studies such as its mechanical properties and high-temperature resistance.

[0110] Figure 2 The surface SEM image of the prepared high-entropy alloy skeleton is shown. It can be seen that the skeleton pores are regular in shape, mostly generated by particle stacking, and the pores are interconnected and evenly distributed, which is conducive to the next step of copper infiltration.

[0111] (4) Place an electrolytic copper sheet with a purity of 99.99% under a high-entropy alloy skeleton, and heat it from room temperature to 1350℃ in a hydrogen atmosphere at a heating rate of 10℃ / min. Hold it at that temperature for 30min, and then cool it to room temperature in the furnace. Remove the remaining copper by machining to obtain a WMoTaNbV copper-infiltrated composite material with a density of 98.8% and a Cu content of 7 wt.%.

[0112] (5) The obtained WMoTaNbV copper-infiltrated composite material has a linear ablation rate of 5.2 μm / s, a compressive strength of 2300 MPa, and a fracture toughness of 18 MPa·m. 1 / 2 The product prepared in this embodiment has the best performance.

[0113] Example 3

[0114] (1) Place W, Mo, Ta, Nb, and V (W 30.4 wt.%, Mo 15.9 wt.%, Ta 29.9 wt.%, Nb 15.4 wt.%, V 8.4 wt.%) with each element having a purity ≥ 99.99% and an equiatomic ratio in a vacuum induction levitation furnace, and evacuate the furnace to 5 × 10⁻⁶. -3 Pa, then fill with argon gas to 0.05 MPa, and melt at 3500℃ 4 times, holding for 10 minutes each time. After the last melting is completed and cooled, a high-entropy alloy ingot is obtained.

[0115] (2) The high-entropy alloy ingot is cut into cylindrical rods with a diameter of 50mm×100mm by wire cutting. The spherical powder with a particle size distribution of 15~53μm and an average particle size (D50) of 30μm is obtained by plasma rotating electrode method (rotation speed 20000rpm, argon protection).

[0116] The powder is passed through a 200-mesh sieve, and stearic acid is weighed at 1.5 wt.% of the powder mass. The stearic acid is dissolved in anhydrous ethanol at 60°C to obtain a solution with a stearic acid content of 2 wt.%. The powder is poured into a stainless steel container and heated and stirred in a water bath at 60°C for 30 minutes. The powder and the solution are mixed at a mass ratio of 5:1 to obtain a slurry.

[0117] The slurry was dried in a vacuum oven at 60°C for 2 hours, then placed into a chrome steel mold and pressed using a universal testing machine. The pressing pressure was 500 MPa and the holding time was 5 minutes to obtain a Φ20×10mm green embryo.

[0118] (3) The green billet is placed in a vacuum sintering furnace and heated from 25°C to 400°C at a heating rate of 80°C / min under a vacuum of 6Pa. It is held for 10 minutes and then cooled to room temperature naturally. Then, under hydrogen protection, it is heated from room temperature to 2200°C at a heating rate of 100°C / min and held for 30 minutes. It is then cooled with the furnace to obtain a high-entropy alloy skeleton with a porosity of 10%.

[0119] (4) Place an electrolytic copper sheet with a purity of 99.99% under a high-entropy alloy skeleton, and heat it from room temperature to 1400℃ in a hydrogen atmosphere at a heating rate of 10℃ / min. Hold it at that temperature for 40min, and then cool it to room temperature in the furnace. Remove the remaining copper by machining to obtain a WMoTaNbV copper-infiltrated composite material with a density of 98.6% and a Cu content of 9 wt.%.

[0120] (5) The obtained WMoTaNbV copper-infiltrated composite material has a linear ablation rate of 5.3 μm / s, a compressive strength of 2260 MPa, and a fracture toughness of 17 MPa·m. 1 / 2 .

[0121] Counterexample 1

[0122] The WMoTaNbV copper-infiltrated composite material was prepared in a manner similar to that in Example 2, except that the pressing pressure was 600 MPa, and the sintering temperature was 250°C in the first stage and 2300°C in the second stage. Specifically:

[0123] (1) Place W, Mo, Ta, Nb, and V (W 30.4 wt.%, Mo 15.9 wt.%, Ta 29.9 wt.%, Nb 15.4 wt.%, V 8.4 wt.%) with each element having a purity ≥ 99.99% and an equiatomic ratio in a vacuum induction levitation furnace, and evacuate the furnace to 5 × 10⁻⁶. -3 Pa, then fill with argon gas to 0.05 MPa, and melt at 3500℃ 4 times, holding for 10 minutes each time. After the last melting is completed and cooled, a high-entropy alloy ingot is obtained.

[0124] (2) The high-entropy alloy ingot is cut into cylindrical rods with a diameter of 50mm×100mm by wire cutting. The spherical powder with a particle size distribution of 15~53μm and an average particle size (D50) of 30μm is obtained by plasma rotating electrode method (rotation speed 20000rpm, argon protection).

[0125] The powder is passed through a 200-mesh sieve, and stearic acid is weighed at 1.5 wt.% of the powder mass. The stearic acid is dissolved in anhydrous ethanol at 60°C to obtain a solution with a stearic acid content of 2 wt.%. The powder is poured into a stainless steel container and heated and stirred in a water bath at 60°C for 30 minutes. The powder and the solution are mixed at a mass ratio of 5:1 to obtain a slurry.

[0126] The slurry was dried in a vacuum oven at 60°C for 2 hours, then loaded into a chrome steel mold and pressed using a universal testing machine. The pressing pressure was 600 MPa and the holding time was 5 minutes to obtain a Φ20×10mm green embryo.

[0127] (3) The green billet is placed in a vacuum sintering furnace and heated from 25°C to 250°C at a heating rate of 80°C / min under a vacuum of 6Pa. It is held for 10 minutes and then naturally cooled to room temperature. Then, under hydrogen protection, it is heated from room temperature to 2300°C at a heating rate of 100°C / min and held for 25 minutes. It is then cooled with the furnace to obtain a high-entropy alloy skeleton with a porosity of 15%.

[0128] (4) Place an electrolytic copper sheet with a purity of 99.99% under a high-entropy alloy skeleton, and heat it from room temperature to 1350℃ in a hydrogen atmosphere at a heating rate of 10℃ / min. Hold it at that temperature for 25min, and then cool it to room temperature in the furnace. Remove the remaining copper by machining to obtain a WMoTaNbV composite material with a density of 98.5% and a Cu content of 0 wt.%.

[0129] Figure 3 A macroscopic photograph of the prepared high-entropy alloy skeleton is shown, which shows that the copper phase has not penetrated into the high-entropy alloy skeleton.

[0130] In this counterexample, stearic acid cannot be completely decomposed at 250℃, leaving residues that block the pores of the skeleton and disrupt its connectivity; 2300℃ leads to excessive sintering and densification of the skeleton, causing a sharp drop in porosity or collapse of the channels, preventing copper from penetrating. As a result, no copper is penetrating into the composite material, and the resulting material has poor ablation performance.

[0131] Comparative Example 1

[0132] W, Mo, Ta, and Nb with a purity ≥99.99% and equiatomic ratio were mixed. The mixed powder was then placed in a ball mill jar with copper powder at a mass ratio of 93% and 7%, and ball milled for 6 hours at 250 r / min under a hydrogen atmosphere with a ball-to-powder ratio of 10:1 to obtain the mixed powder.

[0133] The mixed powder was subjected to spark plasma sintering at a heating rate of 50℃ / min, a sintering temperature of 1300℃, and a holding time of 15min to obtain a refractory high-entropy alloy WMoTaNbCu.

[0134] Figure 4 Macroscopic photographs of the obtained high-entropy alloys are shown. It can be seen that the high-entropy alloys prepared by the mixed sintering method are cylindrical and possess basic formability, but the overall structure is dense and lacks obvious interconnected pores. Due to the lack of interconnected pores, the high-entropy alloys obtained by this process cannot meet the performance requirements that rely on interconnected pores. Furthermore, the isolated copper phases cannot leverage the interconnected structure to achieve synergistic enhancement or functionalization effects, fully demonstrating the advantages of this invention in pore structure control and performance optimization.

[0135] Figure 5 The SEM image of the prepared high-entropy alloy surface shows that the surface of the copper-infiltrated porous framework of the refractory high-entropy alloy prepared in the comparative example has mostly spherical particles. Although gaps exist between the particles, they do not form a uniform and continuous interconnected pore structure. This structure, lacking continuous interconnected pores, is not conducive to the uniform penetration and transport of molten copper. Compared with the framework with a continuous interconnected pore structure prepared in this invention, there are significant differences in terms of porous structure control and performance potential, highlighting the advantages of this invention.

[0136] The ablation rate of the obtained WMoTaNbCu refractory high-entropy alloy line was 15.9 μm / s, and the mass ablation rate was 0.183 g / s.

[0137] It is evident from the above that the mixed sintering method in Comparative Example 1 cannot form a connected porous structure, and the copper phase exists in the form of isolated particles. In contrast, the melt infiltration method in Examples 1-3 forms a three-dimensional connected copper network through the capillary action of a porous framework, significantly improving ablation resistance.

[0138] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A composite material, characterized in that, The composite material comprises a high-entropy alloy skeleton and a copper phase that permeates into its pores. The copper phase fills the pores of the high-entropy alloy skeleton through capillary permeation and interacts with the skeleton to achieve ablation resistance.

2. The composite material according to claim 1, characterized in that, Preferably, the composition expression of the high-entropy alloy skeleton is WMoTaNbX, where X is any one of Ti, V, Zr, and Hf.

3. The composite material according to claim 1, characterized in that, The composition expression of the high-entropy alloy skeleton is WMoTaNbX1X2, where X1 and X2 are each independently selected from any one of Ti, V, Zr, and Hf, and X1 is different from X2.

4. The composite material according to claim 1, characterized in that, The porosity of the high-entropy alloy skeleton is 10%~15%.

5. The composite material according to claim 1, characterized in that, The copper phase content in the composite material is 5~10 wt.%.

6. The composite material according to claim 1, characterized in that, The linear ablation rate of the composite material is 5~6 μm / s.

7. A method for preparing the composite material according to any one of claims 1 to 6, characterized in that, The method includes: Step 1: Melt elemental materials including W, Mo, Ta and Nb into high-entropy alloy ingots; Step 2: Press the high-entropy alloy ingot into a green billet; Step 3: Sinter the green blank to obtain a high-entropy alloy skeleton; Step 4: Infiltrate copper into the high-entropy alloy skeleton to obtain the composite material.

8. The method according to claim 7, characterized in that, In step 1, the elemental substance further includes any one or two of Ti, V, Zr, and Hf.

9. The method according to claim 7, characterized in that, Step 2 includes: Step 2-1: The high-entropy alloy ingot is crushed into powder using the plasma rotating electrode method; Step 2-2: Mix the powder with the forming agent to form a slurry; Steps 2-3 involve drying the slurry and pressing it into a green body.

10. The method according to claim 9, characterized in that, In step 2-2, the forming agent is stearic acid.

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