In-situ synthesis binary heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating as well as preparation method and application of in-situ synthesis binary heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating

Abstract

The invention belongs to the field of additive manufacturing of metal ceramic composite materials, and relates to an in-situ synthesis binary heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating as well as a preparation method and an application of the in-situ synthesis binary heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating. The composite coating is composed of 70%-80% of AlCoCrFeNi high-entropy alloy powder and 20%-30% of an in-situ synthesis reinforced phase precursor material, and the composite coating comprises the following components in percentage by weight: 10.62% of Al, 22.24% of Co, 21.97% of Cr, 24.63% of Fe and the balance of Ni. The mass ratio of the pure Ti powder to the B4C powder is (1.25-1.35): 1. The laser cladding composite powder is adopted for preparing the composite coating, TiC-TiB2 formed in situ is evenly distributed in the coating, the coating structure is refined, good compactness and bonding strength are achieved, the aspects of high-temperature oxidation resistance, abrasion resistance and the like are improved, and the composite coating can be applied to surface repairing and strengthening of key components such as aerospace thermal barrier coating preparation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of additive manufacturing of cermet composite materials, and particularly relates to an in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating, a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in the background of the present application is only intended to increase the understanding of the overall background of the present application, and should not necessarily be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

[0003] In the field of aerospace, thermal barrier coatings and key components such as turbine blades and burners are prone to oxidation and wear under long-term high-temperature service conditions, thus higher requirements are put forward for the performance of thermal structural materials. Traditional high-temperature alloys (such as iron-based, cobalt-based, nickel-based alloys) usually undergo microstructure coarsening at high temperatures, leading to thermal corrosion and cracking, and thus seriously affecting the mechanical properties and combustion efficiency. Therefore, it is urgent to prepare a surface coating with high-temperature oxidation resistance and thermal stability to improve the long-term service life.

[0004] High-entropy alloys have good thermal stability and high-temperature oxidation resistance due to slow diffusion, high entropy, cocktail effect and lattice distortion multi-element synergistic effect. The AlCoCrFeNi high-entropy alloy with BCC+B2 dual-phase structure has excellent thermal stability in high-temperature environment, making it an ideal material for oxidation-resistant protective coatings. However, the traditional AlCoCrFeNi alloy will precipitate brittle σ-rich phase under long-term high-temperature oxidation conditions, leading to cracking of the oxidation layer and accelerating oxidation. This seriously limits its practicality in high-temperature oxidation, thermal corrosion and wear resistance. Therefore, it is urgent to develop a composite coating with high oxidation resistance, high wear resistance and excellent thermal stability. SUMMARY

[0005] In view of the needs of the prior art, the purpose of the present application is to provide an in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating, a preparation method and application thereof. The method uses B4C and Ti as precursors for in-situ synthesis of ceramic reinforcement phase (TiC-TiB2), and uses laser cladding technology to make Ti and B4C powder completely react in the high-entropy alloy, generating network-distributed dual TiC-TiB2 ceramic reinforcement phase. The generated dual-heterogeneous network TiC-TiB2 reinforced phase promotes the AlCoCrFeNi high-entropy alloy coating to exhibit better hardness, wear resistance and high-temperature oxidation resistance.

[0006] Specifically, the present application provides the following technical solutions: In a first aspect, the application provides a method for in-situ synthesizing a dual-heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating, which is composed of 70-80% AlCoCrFeNi high-entropy alloy powder and 20-30% in-situ synthesized reinforced phase precursor material by weight percentage, wherein the AlCoCrFeNi high-entropy alloy powder contains Al 10.62%, Co 22.24%, Cr 21.97%, Fe 24.63%, and the balance of Ni; the in-situ synthesized reinforced phase precursor material contains pure Ti powder and B4C powder, and the mass ratio of the pure Ti powder to the B4C powder is 1.25-1.35:1; and the TiC-TiB2 ceramic phase in the composite coating is uniformly distributed in a dual-heterogeneous reticular form.

[0007] Preferably, the in-situ synthesized dual-heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating is composed of 80% AlCoCrFeNi high-entropy alloy powder and 20% in-situ synthesized reinforced phase precursor material by weight percentage, wherein the mass ratio of the pure Ti powder to the B4C powder is 1.3:1.

[0008] Preferably, the particle size of the AlCoCrFeNi high-entropy alloy powder is 45-105 μm, the particle size of the pure Ti powder is 43-106 μm, the purity of the pure Ti powder is 99.5%, and the particle size of the B4C powder is 20-70 μm, and the purity of the B4C powder is 99.9%.

[0009] In a second aspect, the application provides a method for preparing the in-situ synthesized dual-heterogeneous reticular TiC-TiB2 reinforced high-entropy alloy composite coating, which comprises the following steps: pre-reacting Ti and B4C, ball-milling the mixed powder with AlCoCrFeNi high-entropy alloy powder, vacuum drying and sieving the slurry obtained after the ball-milling to obtain a mixed powder, and then performing laser cladding on the mixed powder to form a composite coating on the surface of a substrate.

[0010] Preferably, the pre-reaction comprises the following steps: wet-milling Ti and B4C to mix them thoroughly, setting the ball-to-material ratio to 1:1, using anhydrous ethanol as a solvent, and ball-milling at a speed of 180-200 rpm for 0.5-1 h; and then placing the mixed precursor powder in a vacuum drying oven for drying treatment, wherein the temperature of the vacuum drying is 110-130℃, and the time is 5-8 h. The above pre-reaction can ensure the sufficient generation of ceramic phases and inhibit the influence of the introduction of Ti and B4C on the phases and properties of the high-entropy alloy.

[0011] Preferably, the ball-milling is wet ball-milling, the ball-to-material ratio is set to 1:3, anhydrous ethanol is used as a solvent, and the ball-milling is performed at a speed of 150-250 rpm for 2-3 h.

[0012] Preferably, the temperature of the vacuum drying is 110-130 DEG C, and the time is 13-20 h.

[0013] Preferably, the sieving is performed by using 320 mesh and 800 mesh sieves in sequence.

[0014] Preferably, the process parameters of the laser cladding treatment are as follows: laser power is 1500-2000 W, cladding speed is 1300-1600 mm / s, lap rate is 50-65%, and spot diameter is 1.5-2.5 mm.

[0015] Preferably, the thickness of the coating formed by the laser cladding treatment is 8-10 mm.

[0016] In a third aspect, the application provides a use of the in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy AlCoCrFeNi composite coating in the preparation of thermal barrier coating bonding layers, turbine blades, and surface strengthening and repairing of combustors.

[0017] The application achieves the following beneficial effects by using one or more of the above technical solutions: (1) The dual-heterogeneous network TiC-TiB2 reinforced AlCoCrFeNi high-entropy alloy coating provided by the application is uniformly dispersed with TiB2 as the network core node, and TiC extends from the node in the form of dendrites to form a uniform network structure. This design not only enhances the mechanical properties of the coating, but also avoids the performance unevenness caused by the aggregation of the reinforcing phase (promotes the strengthening of the grain boundary, the change of the grain boundary orientation, and the increase of the dislocation density).

[0018] (2) The application uses laser cladding technology to ensure high bonding strength, density, wear resistance, corrosion resistance, and oxidation resistance of the coating and the substrate, and accurately controls the shape of the coating, which is suitable for surface repairing and strengthening of thermal barrier coating bonding layers and complex components (such as turbine blades).

[0019] (3) The application optimizes the pre-reaction and ball milling process (the precursor material Ti powder and B4C powder are first compounded to make Ti and B4C fully react, and then mixed with AlCoCrFeNi alloy powder for coating preparation) to ensure the in-situ uniform generation of TiC-TiB2, avoid the influence of the introduction of Ti on the high-entropy alloy phase and performance, and promote the uniform distribution and generation of the reinforcing phase, i.e., avoid the formation of brittle intermetallic compounds and reduce the risk of thermal cracks.

[0020] (4) The hardness of the composite coating is significantly improved, and the wear volume is greatly reduced by the in-situ synthesized dual-heterogeneous network TiC-TiB2 ceramic reinforcing phase. Among them, the polyhedral TiB2 is uniformly dispersed in the coating as the network core node, and the TiC phase exhibits dendritic growth behavior. In the process of friction and wear, the node TiB2 particles are fixed in the coating to form a hard hard phase, reducing the direct contact between the friction pair and the coating, and the TiC dendritic structure acts as a support for the fixed base and as a skeleton, thereby reducing the ploughing effect and adhesive wear.

[0021] (5) The composite coating obtained by the application has high-temperature oxidation resistance. The network TiC-TiB2 forms a pinning effect at the grain boundary, inhibits the diffusion of cations, changes the activity and diffusion coefficient of Al in the alloy coating, and improves the oxidation resistance of the coating. Specifically, the segregation of fine ceramic particles at the grain boundary and dislocation zone significantly increases the grain boundary density and subgrain boundary proportion, promotes the effective diffusion of Al and Cr active elements along the grain boundary, inhibits the migration of metal ions such as Fe and Ni to the oxidation film and the internal diffusion of O ions, and forms a more uniform and stable inner dense Al2O3 oxidation layer and outer TiO2-Cr2O3 composite oxidation film, so that the stability of the oxidation film is enhanced, and the oxidation resistance of the coating is further improved.

[0022] (6) The application realizes the comprehensive improvement of high-entropy alloy coating in hardness, wear resistance, high-temperature oxidation resistance and thermal stability by innovative design of dual-heterogeneous network TiC-TiB2 reinforcing phase and optimized laser cladding process, and provides an efficient solution for material application in high-temperature harsh environment (such as aerospace field, thermal barrier coating bonding layer, turbine blade, combustion chamber, etc.). BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of the application form a part of the application and serve to further understand the application. The schematic embodiments of the application and the description thereof are used to explain the application, and do not constitute an improper limitation on the application.

[0024] Figure 1 The isomorphic network ceramic reinforcing phase TiC-TiB2 morphology and coating XRD spectrum in the application embodiment 1, wherein (a) is the isomorphic network ceramic reinforcing phase TiC-TiB2 morphology, (b) is the coating XRD spectrum, (c) is the point scanning data of the marked position point 1 in (a), (d) is the point scanning data of the marked position point 2 in (a), and (e) is the point scanning data of the marked position point 3 in (a); Figure 2 The microstructure morphology, reverse pole figure, grain boundary figure and core average bias thermal figure of the coating prepared in the application embodiments 1-2 are shown in the following table: Figure 3Microstructure morphology, reverse pole figure, grain boundary figure, and average nucleation bias thermal figure of the coating prepared in Inventive Comparative Examples 1-2; Figure 4 Wear morphology of the coating prepared in Inventive Examples 1-2 and Comparative Examples 1-2; Figure 5 XRD patterns of the oxide film of the coating prepared in Inventive Example 1 and Comparative Example 2 at different temperatures, wherein (a) is at 700°C, (b) is at 800°C, and (c) is at 900°C; Figure 6 Surface morphology of the coating prepared in Inventive Examples 1-2 and Comparative Examples 1-2 after oxidation at 700°C for 200 h; Figure 7 Surface morphology of the coating prepared in Inventive Examples 1-2 and Comparative Examples 1-2 after oxidation at 800°C for 200 h; Figure 8 Surface morphology of the coating prepared in Inventive Examples 1-2 and Comparative Examples 1-2 after oxidation at 900°C for 200 h; Figure 9 Cross-sectional morphology and element distribution of the oxide film of the coating prepared in Inventive Example 1 after oxidation at different temperatures for 200 h. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0026] In order to enable a person skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.

[0027] Example 1 The present embodiment provides an in-situ synthesized dual-element heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating and a preparation method thereof In the present embodiment, the in-situ synthesized dual-element heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating comprises the following components (in terms of weight percentage): 80% of AlCoCrFeNi high-entropy alloy powder and 20% of in-situ synthesized reinforced phase precursor material; In the AlCoCrFeNi high-entropy alloy powder, the content of each element component is as follows: Al: 10.62%, Co: 22.24%, Cr: 21.97%, Fe: 24.63%, and the balance is Ni; The in-situ synthesized reinforcing phase precursor material includes pure Ti powder (purity 99.5%, particle size 43-106 μm) and B4C powder (purity 99.9%, particle size 20-70 μm), and the mass ratio of Ti to B4C powder is 1.3:1.

[0028] The specific preparation method is as follows: (1) Before mixing, Ti and B4C are fully reacted, and wet milling method is selected to fully mix Ti and B4C, the ball-to-material ratio is set to 1:1, the solvent is anhydrous ethanol, and the ball milling is carried out at a speed of 200 rpm for 1 h, and then 2 h of drying treatment is carried out. Avoid the influence of Ti and B4C introduced in HEA on the phase and performance of high-entropy alloy.

[0029] (2) The AlCoCrFeNi high-entropy alloy powder (particle size 45-105 μm) of the above ratio and the pre-processed in-situ synthesized reinforcing phase precursor material are uniformly mixed. Then, it is placed in a ball mill jar, stainless steel balls are added according to a ball-to-material ratio of 1:3, and anhydrous ethanol is added to two-thirds of the ball mill jar. Then, the ball mill jar is sealed and placed in a ball mill for 2.5 h. After ball milling, the ball-powder-ethanol slurry is then placed in a 120°C vacuum drying oven for 15 h. Then, 320 mesh and 800 mesh sieves are used to screen the composite powder to remove stainless steel balls, large particles and broken particle fragments in the composite powder, and obtain uniformly mixed powder.

[0030] (3) The mixed powder prepared in step (1) is melted on the surface of 45 steel by laser cladding technology, and a composite coating with a thickness of 1 cm is obtained. The process parameters of laser cladding are as follows: laser power 1800 W, cladding speed 1500 mm / s, powder feeding rate 1.2 rad / min, protective gas flow rate 12 L / min, protective gas argon, overlap rate 60%, and spot diameter 2 mm.

[0031] (4) Under the process parameters, the precursor material will undergo the following reactions in the molten pool: (5) Ti+C→TiC. (6) Ti+2B→TiB2. (7) B4C→4B+C. (8) Cr+B→CrB. (9) Cr+2B→CrB2. (10) Fe+B→FeB. (11) Fe+2B→CrB2. (12) Ni+B→NiB. (13) 3Cr+2C→Cr3C2. (14) 7Cr+3C→Cr7C3. (15) Ti + 1 / 3Cr7C3→ TiC + 7 / 3Cr. (16) Based on Gibbs free energy and calculation , TiC and TiB2 will preferentially form under lower Gibbs free energy driving, while TiB2 has a high melting point and a dense structure, which can quickly nucleate and grow. TiC is inhomogeneous nucleation on the surface of TiB2, and can also nucleate on the surface of TiC or TiB2 that has been precipitated, further inhibiting the formation of brittle intermetallic compounds such as metal carbides and metal borides, and avoiding the generation of thermal cracks during cladding, which affects the quality of the coating.

[0032] (17) As described above, due to the initial precipitation and rapid growth of TiB2, B will be depleted first, forming a hexagonal TiB2 phase. Thereafter, TiC is heterogeneously nucleated on the surface of TiB2, and the later-precipitated ceramic phase is mainly TiC. Finally, a dual-heterogeneous network of polyhedral TiB2 as the core node and TiC as the obvious dendritic growth behavior is formed.

[0033] (18) After laser cladding is completed, an in-situ dual-heterogeneous network AlCoCrFeNi + (TiC -TiB2) 20 high-entropy alloy coating is formed on the surface of the 45 steel substrate with a thickness of 1 mm.

[0034] Example 2 : The embodiment provides an in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating and a preparation method. The difference between the embodiment and embodiment 1 is that the in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating comprises the following components (in percentage by weight): 70% of AlCoCrFeNi high-entropy alloy powder and 30% of in-situ synthesized reinforced phase precursor material; the content of other components and the preparation method are consistent with those of embodiment 1. After laser cladding is completed, an in-situ dual-heterogeneous network AlCoCrFeNi + (TiC -TiB2) 30 high-entropy alloy coating is formed on the surface of the 45 steel substrate with a thickness of 1 mm.

[0035] During the coating cladding process of the embodiment, as the content of the TiC-TiB2 precursor for in-situ synthesis of ceramic reinforced phase in the coating increases, TiB2 has sufficient growth time, and at the same time, a small amount of TiC begins to precipitate and heterogeneously nucleates on the surface of each other.

[0036] Comparative Example 1 : The difference between this comparative example and Example 1 is that the in-situ synthesized binary heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating contains the following components (by weight percentage): 90% AlCoCrFeNi high-entropy alloy powder and 10% in-situ synthesized reinforcing phase precursor material; the content of other components and the preparation method are the same as in Example 1.

[0037] Comparative Example 2 : The difference between this comparative example and Example 1 is that the in-situ synthesized binary heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating contains the following components (by weight percentage): 100% AlCoCrFeNi high-entropy alloy powder, without the addition of in-situ synthesized reinforcing phase precursor material; the content of other components and the preparation method are the same as in Example 1.

[0038] Comparative Example 3 : The difference between this comparative example and Example 1 is that the in-situ synthesized binary heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating contains the following components (by weight percentage): 60% AlCoCrFeNi high-entropy alloy powder, 40% in-situ synthesized reinforcing phase precursor material, and the content and preparation method of other components are the same as in Example 1.

[0039] Experimental Example 1 This experimental example describes the structural determination of the in-situ synthesized binary heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coatings prepared in Examples 1-3. The microstructure analysis of the coating is shown in Table 1. Table 1

[0040] like Figure 1 As shown in Figure (a), isomeric TiC, TiB2, and TiC-TiB2 ceramic reinforcing phases were generated in situ in the embodiment. Figure 1 As shown in (b), energy-dispersive X-ray spectroscopy shows that with the increase of the content of the in-situ synthesized reinforcing phase precursor materials (Ti and B4C), the diffraction peak intensity of the in-situ ceramic reinforcing phase (TiC-TiB2) in the coating increases significantly.

[0041] like Figure 1 As shown in (c), based on at.%, the dark hexahedron is inferred to be TiB2, combined with... Figure 1 In (a) TiB2 is uniformly dispersed in the coating as the core nodes of the network; for example... Figure 1 As shown in (d), based on at.%, this region exhibits a TiC-TiB2 phase composite structure. Previous analysis indicates that TiC undergoes heterogeneous nucleation and growth on the TiB2 surface, forming a binary ceramic phase composite structure. Figure 1As shown in (e), based on at.%, the gray area is inferred to be TiC, exhibiting a dendritic growth morphology that spreads outward from the TiB2 node and branches to form a heterogeneous network structure.

[0042] like Figure 2 As shown in (a1) and (b1), in the embodiments of the present invention, after adding 20%~30% in-situ synthesized reinforcing phase precursor materials (Ti and B4C), a submicron to micron-scale binary heterogeneous network TiC-TiB2 reinforcing phase was formed within the AlCoCrFeNi high-entropy alloy coating. In Comparative Example 1 ( Figure 3 In Comparative Example 3 (c1), after segregation occurs within the molten pool, ceramic phases still precipitate due to insufficient in-situ synthesized powder content. However, the small amount of powder used for in-situ ceramic synthesis is insufficient, and after cladding, the mixed ceramic phase is only dispersed in the coating as small particles, failing to form a network structure. In Comparative Example 3, due to the increase in the content of Ti and B4C in the in-situ synthesized reinforcing phase precursor materials, the excessive content of Ti and B4C powder in the molten pool makes it difficult to observe the formation of the titanium-depleted region. At the same time, a small amount of TiC begins to precipitate and nucleates heterogeneously on each other's surfaces with TiC and TiB2. The previously grown TiB2 and the subsequently precipitated TiB2 have inconsistent orientations in the particle and crystal axis (e.g., TiC-TiB2) combination, which allows TiB2 sufficient nucleation and growth time, resulting in aggregation. This transformation leads to the formation of shorter blocky or rod-shaped structures in the TiB2 phase, and the irregular shape prevents the formation of a network structure. Under the same preparation process, when the precursor content in Example 1 of this application is 20%, TiC-TiB2 exhibits a network distribution. The polyhedral TiB2 phase exhibits a uniformly distributed hexahedral structure, serving as the core nodes of the network dispersed throughout the coating. The TiC phase, on the other hand, displays a distinct dendritic growth behavior, spreading outward from the TiB2 nodes and branching to form a heterogeneous network structure.

[0043] As shown in Table 1 and Figure 2 As shown in (a2) and (b2), compared to the relative proportion 2 without ceramic reinforcement, Figure 3 The average grain size of the coating in Example 1 (c2) shows a significant refinement of the microstructure. Simultaneously, with the increase in the content of the in-situ synthesized reinforcing phase precursor material, the reaction time is shortened, leaving insufficient time for grain growth, thus achieving grain refinement. Furthermore, TiC-TiB2 preferentially precipitates and forms nucleation sites, which inhibit further grain growth, leading to significant refinement of the coating structure. Specifically, the coating structure refinement rate obtained in Example 1 reached 41.2% (grain size 7.69 μm), in Example 2 it was 23.96% (grain size 9.96 μm), in Comparative Example 1 it was 37.87% (grain size 8.12 μm), and in Comparative Example 3 it was 21.84% (grain size 10.19 μm).

[0044] As shown in Table 1 and Figure 2 As shown in (a3) ​​and (b3), the in-situ binary heterogeneous network TiC-TiB2 reinforced phase prepared in the embodiments of the present invention significantly improves the grain boundary density in the coating. At the same time, the grain boundary orientation in the coating changes from high-angle grain boundaries (LAGBs) to subgrain boundaries (SGBs). Subgrain boundaries are composed of specific arrangements of dislocations, such as dislocation cells and dislocation walls. Under high temperature conditions, a high proportion of subgrain boundaries is beneficial to improving the thermal stability of the structure and suppressing the formation of brittle oxides.

[0045] As shown in Table 1 and Figure 2 As shown in (a4) and (b4), the nuclear mean bias (KAM) thermal maps reveal that the in-situ binary heterogeneous network TiC-TiB2 reinforcing phase prepared in this embodiment of the invention significantly improves the KAM value within the coating. The increase in KAM represents an extremely high dislocation density, reflecting the strong work hardening performance of Example 1.

[0046] Experimental Example 1 This experiment tested the performance of the coating materials prepared in Examples 1-3 and Comparative Examples 1-3. (1) Wear performance test, the specific data are shown in Table 2: Table 2

[0047] From the data in Table 1 and Figure 4 Analysis shows that the binary heterogeneous network reinforcing phase composed of TiC-TiB2 significantly improves the wear resistance of the coating in both room temperature and 400°C high-temperature environments. Under the same preparation process, the coating with 20% binary heterogeneous network TiC-TiB2 reinforcing phase exhibits a smoother surface on the wear track under heavy loads, without large-area lamellar peeling or detachment.

[0048] like Figure 4 As shown, the in-situ synthesis of binary heterogeneous network TiC-TiB2 not only provides grain boundary strengthening and second-phase strengthening, but also significantly enhances the average hardness of the coating due to the work hardening properties brought about by the high density of dislocations within the coating. During the friction and wear process, the high-hardness TiB2 acts as a hard bearing phase anchored within the coating, reducing direct contact between the friction pair and the coating. The dendritic TiC fixes the coating, effectively resisting plastic deformation and achieving an anchoring and strengthening effect.

[0049] (2) High-temperature antioxidant performance test, the specific data are shown in Table 3: Table 3

[0050] Analysis of the data in Table 2 shows that the binary heterogeneous network ceramic reinforcing phase (TiC-TiB2) significantly reduces the oxidation weight gain of the AlCoCrFeNi coating, exhibiting superior oxidation resistance. In Comparative Example 1, due to insufficient precursor powder content from in-situ synthesis, the segregated ceramic phase still precipitates in the Fe- and Cr-rich phases, but it is insufficient to form a network structure and cannot create a pinning effect at grain boundaries. The mixed ceramic phase can only be discretely distributed in the Fe- and Cr-rich phases, weakening the inhibition of metal ion diffusion and causing a decrease in oxidation resistance. In Comparative Example 2, under high-temperature oxidation conditions, excessive Fe and Ni accumulate on the oxide film surface to form oxides, while cracks and spalling cause severe internal oxidation, leading to increased oxidation weight gain. In Comparative Example 3, due to the uneven distribution of a large amount of TiC-TiB2 within the coating, and the segregation and aggregation of TiB2 as nodes and TiC as veins to form blocky or short rod-shaped morphologies, under high-temperature conditions, these become short-circuit channels for rapid element diffusion, exacerbating oxidation.

[0051] like Figure 5 The image shows the XRD patterns of the coating materials prepared in Example 1 and Comparative Example 2 after oxidation for 200 h. The oxide film is mainly composed of Al2O3, Cr2O3, TiO2, and a small amount of spinel oxide. The binary heterogeneous network ceramic reinforcing phase TiC-TiB2 significantly improves the diffraction peak intensity of Al2O3 and Cr2O3, while suppressing unstable Fe2O3 and Fe3O4 oxides.

[0052] like Figures 6~8 The figures show the morphology and composition of the oxide films of the coating materials prepared in the embodiments and comparative examples of the present invention after oxidation at different temperatures for 200 h. No cracks were found in the oxide films of the embodiments, and no Al2O3 island regions oxidized due to oxygen penetration were formed inside the coating. EDS analysis showed that the outer oxide film was rich in Cr oxide, and the Ti content gradually increased from the inner layer to the outer layer of the oxide film. Al, however, showed the opposite trend, forming a dense Al2O3 layer in the inner layer of the oxide film. Thanks to grain boundary strengthening and the formation of subgrain boundaries, the introduction of ceramic particles promoted the formation of the internal Al2O3 oxide film and triggered intergranular oxidation, forming a dense layer composed of active element compounds between the oxide film and the coating interface. This hindered the outward diffusion of cations in the coating, and the dense inner Al2O3 protective oxide layer further weakened the inward diffusion of O.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. In-situ synthesized dual-phase heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating, characterized in that, Composed of 70%~80% AlCoCrFeNi high-entropy alloy powder and 20%~30% in-situ synthesized reinforcing phase precursor material by weight percentage, wherein the content of each element in the AlCoCrFeNi high-entropy alloy powder is: Al: 10.62%, Co: 22.24%, Cr: 21.97%, Fe: 24.63%, and the balance is Ni; the in-situ synthesized reinforcing phase precursor material comprises pure Ti powder and B4C powder, and the mass ratio of pure Ti to B4C powder is 1.25~1.35:1; and the TiC-TiB2 ceramic phase in the composite coating is uniformly distributed in a dual-heterogeneous network.

2. The in-situ synthesized dual heterogeneous network TiC-TiB2 reinforced high entropy alloy composite coating of claim 1, wherein, The in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating is composed of 80% AlCoCrFeNi high-entropy alloy powder and 20% in-situ synthesized reinforcing phase precursor material by weight percentage, wherein the mass ratio of pure Ti to B4C powder is 1.3:

1.

3. The in-situ synthesized dual heterogeneous network TiC-TiB2 reinforced high entropy alloy composite coating of claim 1, wherein, The particle size of the AlCoCrFeNi high-entropy alloy powder is 45~105 μm, the particle size of the pure Ti powder is 43~106 μm, the purity is 99.5%, and the particle size of the B4C powder is 20~70 μm, the purity is 99.9%.

4. A method for in-situ synthesis of dual heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating according to any one of claims 1-3, characterized in that, Specifically, Ti and B4C are pre-reacted, then the mixed powder and AlCoCrFeNi high-entropy alloy powder are ball milled, the slurry obtained after ball milling is vacuum dried and sieved to obtain a mixed powder, and then the mixed powder is subjected to laser cladding treatment to form a composite coating on the surface of the substrate.

5. The production method according to claim 4, wherein The pre-reaction is to mix Ti and B4C by wet milling method, set the ball-to-material ratio to 1:1, use anhydrous ethanol as the solvent, and ball mill at a speed of 180~200 rpm for 0.5-1 h; then the mixed precursor powder is placed in a vacuum drying oven for drying treatment, the temperature of the vacuum drying is 110~130℃, and the time is 5-8 h.

6. The production method according to claim 4, wherein The ball milling is wet ball milling, the ball-to-material ratio is set to 1:3, anhydrous ethanol is used as the solvent, and the ball milling is carried out at a speed of 150~250 rpm for 2~3 h. Preferably, the temperature of the vacuum drying is 110~130℃, and the time is 13~20 h.

7. The production method according to claim 4, wherein The sieving is sieving the composite powder using 320 mesh and 800 mesh sieves in sequence.

8. The production method according to claim 4, wherein The process parameters of the laser cladding treatment are: laser power 1500~2000 W, cladding speed 1300~1600 mm / s, overlap rate 50~65%, and spot diameter 1.5~2.5 mm.

9. The production method according to claim 4, wherein The thickness of the coating formed by the laser cladding treatment is 8~10 mm.

10. Application of the in-situ synthesized dual-heterogeneous network TiC-TiB2 reinforced high-entropy alloy composite coating of any one of claims 1~3 in the preparation of aerospace thermal barrier coatings, the surface strengthening and repair of turbine blades and combustion chambers.

Images