Preparation method of nickel-based high-temperature alloy / eutectic high-entropy alloy layered composite material

Abstract

The invention relates to a nickel-based high-temperature alloy / eutectic high-entropy alloy layered composite material and a preparation method and application thereof. The preparation method comprises the following steps: respectively preparing a nickel-based high-temperature alloy sheet and a eutectic high-entropy alloy sheet by adopting a cold isostatic pressing process, and etching trapezoidal grooves and complementary bulges on the surfaces of the nickel-based high-temperature alloy sheet and the eutectic high-entropy alloy sheet by adopting a high-pressure water jet cutting technology; alternately stacking the two thin plates to form a mechanical interlocking structure; performing vacuum hot-pressing compounding to realize interface diffusion bonding; then carrying out directional solidification treatment to obtain a columnar crystal and eutectic structure; and finally, the surface performance is improved through two-stage shot peening strengthening. The composite material prepared through the method has high-strength interface bonding (larger than or equal to 500 MPa), the room-temperature tensile strength larger than or equal to 1200 MPa, the ductility larger than or equal to 15%, the 1000-DEG C high-temperature endurance life improved by 40-60% compared with a single nickel-based high-temperature alloy and the creep rate smaller than or equal to 1 * 10 s, and has the characteristic that columnar crystals penetrate through multiple layers. The composite material is suitable for high-temperature fields such as aero-engine turbine blades and gas turbine hot end components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance metal matrix composite material preparation, in particular to a nickel-based superalloy / eutectic high-entropy alloy laminated composite material and a preparation method and application thereof. The material is particularly suitable for high-temperature and high-stress environments such as turbine blades of an aero-engine and hot end components of a gas turbine. BACKGROUND

[0002] Nickel-based superalloys have long been the key material for hot end components of aero-engines and gas turbines due to their excellent high-temperature strength, creep resistance and good oxidation and corrosion resistance. However, with the development of aerospace technology, the requirements for engine operating temperature and thrust-to-weight ratio are continuously increasing, and the performance of traditional nickel-based superalloys has gradually approached its theoretical limit. Eutectic high-entropy alloys (EHEAs) are a new type of high-performance material developed in recent years, and their typical representative is AlCoCrFeNi 2.1 alloy. This type of material has high strength and high hardness through unique eutectic organization design, as well as good casting performance and room temperature plasticity of traditional eutectic alloys. However, compared with the most advanced nickel-based single-crystal superalloys, there is still a certain gap in high-temperature durability and creep resistance. The combination of nickel-based superalloys and eutectic high-entropy alloys to form a laminated composite material can theoretically give full play to the advantages of the two materials and achieve performance complementation. However, the existing composite material preparation technology faces two main technical problems: first, the low interfacial bonding strength of dissimilar materials, and the interfacial stress concentration and cracks are easily generated in the preparation process due to the difference in thermal physical properties of the two alloys; second, the conventional composite process cannot maintain the eutectic organization characteristics of the eutectic high-entropy alloy, making it difficult to fully exert its performance potential. Therefore, it is of great significance to develop a preparation method that can achieve high-strength interfacial bonding and maintain the eutectic organization characteristics of the eutectic high-entropy alloy for obtaining high-performance laminated composite materials. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a preparation method of a nickel-based superalloy / eutectic high-entropy alloy laminated composite material. The method ensures high-strength interfacial bonding and maintains the eutectic organization characteristics of the eutectic high-entropy alloy through innovative mechanical interlocking structure design and directional solidification treatment, thereby obtaining a laminated composite material with excellent comprehensive performance. Another object of the present application is to provide a laminated composite material prepared by the above method, which has high-strength interfacial bonding and excellent room temperature and high-temperature mechanical properties. To achieve the above-mentioned objects, the present application adopts the following technical solutions: A preparation method of a nickel-based superalloy / eutectic high-entropy alloy laminated composite material, comprising the following steps: (1) Nickel-based superalloy sheet pretreatment: A cold isostatic pressing process is used to prepare a nickel-based superalloy sheet with a thickness of 0.5-2 mm. A high-pressure water jet cutting technology (water pressure 300-500 MPa, nozzle diameter 0.1-0.3 mm) is used to etch a trapezoidal groove on the surface with a depth of 30-50% of the plate thickness, and the groove spacing is 1.5-2 times the plate thickness. This step lays the foundation for the subsequent formation of a mechanical interlocking structure.

[0004] (2) Eutectic high-entropy alloy sheet pretreatment: A cold isostatic pressing process is used to prepare a eutectic high-entropy alloy sheet with a matching thickness. A water jet cutting technology with the same parameters is used to etch a complementary convex structure to the groove shape in step (1), with a convex height tolerance of ±0.05 mm. Precise tolerance control ensures the accuracy and quality of subsequent assembly.

[0005] (3) Alternating layer assembly: The grooved sheets prepared in steps (1) and (2) are alternately stacked in the order of "superalloy-high-entropy alloy", with the grooves and convexes of adjacent layers forming a mechanical interlocking structure. The number of layers is 5-30. This design not only increases the interface contact area, but also effectively relieves thermal stress through mechanical interlocking effect.

[0006] (4) Vacuum hot pressing composite: The stacked assembly is placed in a vacuum hot pressing furnace, heated to 1100-1200°C at a rate of 10-15°C / min under a vacuum of 0.01-0.1 Pa, and a pressure of 20-50 MPa is applied for 1-3 h to realize interface diffusion bonding. This step realizes the metallurgical bonding of the interface.

[0007] (5) Directional solidification treatment: The hot-pressed composite billet is placed in a directional solidification furnace, with a temperature gradient of 50-100°C / cm and a pulling speed of 5-20 μm / s to obtain a composite material with columnar crystal structure. This key step allows the eutectic high-entropy alloy to maintain its eutectic organization characteristics and fully exploit its performance advantages.

[0008] (6) Surface shot peening: Ceramic pellets with a diameter of 0.2-0.5 mm are used to perform shot peening on the surface of the composite material at a speed of 100-200 m / s, with a coverage rate of 300-500% and a surface roughness of Ra 0.8-1.6 μm. This step improves the fatigue performance and surface quality of the material.

[0009] Preferably, the nickel-based superalloy sheet in step (1) has a composition of Ni-15Cr-8Co-5Mo-4W-3Al-2Ti-1Nb (wt%), with an oxygen content of ≤50 ppm. This composition design ensures the high-temperature performance and purity of the material.

[0010] Preferably, the composition of the eutectic high-entropy alloy sheet in step (2) is AlCoCrFeNi 2.1 , wherein the Ni content deviation is controlled within ±0.05at%, and accurate composition control ensures the accuracy of the eutectic reaction.

[0011] Preferably, the cross-sectional shape of the grooves and protrusions in steps (1) and (2) is an isosceles trapezoid with a base angle of 60-75°, and the surface roughness Ra is ≤1.0μm, which optimizes the mechanical interlocking effect and interface bonding quality.

[0012] Preferably, in the lamination assembly process of step (3), preheating treatment at 800-1000℃ for 1-3min is performed every 5 layers to eliminate accumulated stress, which prevents deformation and damage caused by stress accumulation.

[0013] Preferably, in the hot pressing process of step (4), a 20-50nm thick Ni / Ti composite intermediate layer is pre-placed at the interface, and the introduction of the intermediate layer further promotes interface diffusion and improves bonding strength.

[0014] Preferably, the directional solidification in step (5) adopts zone melting method, the melting zone width is controlled within 10-15mm, and a static magnetic field of 0.1-0.5T is applied. The application of the static magnetic field suppresses the convection of the melt, which is beneficial to obtain more uniform directional solidification structure.

[0015] Preferably, the shot peening in step (6) is carried out in two stages: the first stage uses larger shot particles (0.3-0.5mm) for rough peening, and the second stage uses smaller shot particles (0.1-0.2mm) for fine peening, which realizes the dual effects of deep strengthening and surface finishing through staged processing.

[0016] The application also provides a nickel-based superalloy / eutectic high-entropy alloy layered composite material prepared by any of the above methods, which has an interface bonding strength ≥500MPa and a high-temperature (1000℃) endurance life 40-60% higher than that of a single nickel-based superalloy.

[0017] The composite material has an alternating layered structure, with a single layer thickness of 0.3-1.5mm, an interface diffusion layer thickness of 5-15μm, and columnar crystals penetrating 3-5 material layers, and this unique microstructure is the basis for its excellent performance.

[0018] The composite material has a room temperature tensile strength ≥1200MPa, an elongation ≥15%, and a creep rate ≤1×10⁻ 7 s⁻¹ at 1000℃ / 100MPa, which indicates that the material has excellent comprehensive mechanical properties.

[0019] Compared with the prior art, the present application has the beneficial effects that: (1) Innovative composite structure design: through the precise machining of mechanical interlocking structure (trapezoidal groove / protrusion), the interface contact area is greatly increased, and the thermal stress is effectively relieved through the mechanical interlocking effect, laying the foundation for obtaining high-strength interface bonding.

[0020] (2) Maintaining the organizational characteristics of eutectic high-entropy alloy: through directional solidification treatment, the eutectic high-entropy alloy layer forms a regular directional columnar crystal organization, maintaining its unique eutectic organization characteristics and performance advantages, which cannot be achieved by conventional composite processes.

[0021] (3) High interface bonding strength: combined with mechanical interlocking and optimized hot pressing process, the interface bonding strength reaches more than 500 MPa, which is much higher than that of traditional diffusion welding method.

[0022] (4) Excellent comprehensive performance: the composite material has excellent high-temperature performance of nickel-based high-temperature alloy and high strength, good plasticity of eutectic high-entropy alloy, and the high-temperature endurance life is significantly improved.

[0023] (5) Good process controllability: the entire process flow parameters are clear, and each step cooperates with each other to form a complete process system, which is conducive to industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Microstructure diagram of the composite material obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0025] The present application will be described in detail below through specific examples, but the protection scope of the present application is not limited to the following examples. Example 1

[0026] Step (1) Nickel-based high-temperature alloy sheet pretreatment: a nickel-based high-temperature alloy sheet with a thickness of 1.0 mm is prepared by cold isostatic pressing process under a pressure of 300 MPa, and its chemical composition (wt%) is: Ni-15Cr-8Co-5Mo-4W-3Al-2Ti-1Nb, and the oxygen content is detected as 35 ppm. Using a high-pressure water jet cutting device, set the water pressure to 400 MPa, and use a diamond nozzle with a diameter of 0.2 mm to etch a trapezoidal groove with a depth of 0.4 mm (40% of the plate thickness) on the surface of the sheet. The cross section of the groove is an isosceles trapezoid with a bottom angle of 70°, and the groove spacing is 1.8 mm (1.8 times the plate thickness). The surface roughness Ra value after processing is 0.8 μm.

[0027] Step (2) Eutectic high-entropy alloy sheet pretreatment: a eutectic high-entropy alloy sheet with a thickness of 1.0 mm is prepared by the same cold isostatic pressing process, and its composition is AlCoCrFeNi 2.1(at%), and the Ni content was 33.05 at% (deviation +0.03 at%) detected by inductively coupled plasma mass spectrometer (ICP-MS). Using the same parameters of high-pressure water jet cutting technology, a convex structure completely complementary to the groove shape in step (1) was etched. The convex height was 0.4 mm, the height tolerance was controlled within ±0.03 mm, and the surface roughness Ra value was 0.7 μm.

[0028] Step (3) alternate stacking assembly: the two pre-processed sheets were alternately stacked in the order of "nickel-based superalloy-eutectic high-entropy alloy", and a total of 12 layers were stacked. The grooves between adjacent layers precisely matched the convexes, forming a firm mechanical interlocking structure. During the stacking process, after every 4 layers were stacked, the assembly was placed in a preheating furnace at 850°C for 2 minutes to eliminate the accumulated stress caused by mechanical assembly.

[0029] Step (4) vacuum hot pressing composite: the stacked assembly was placed in a vacuum hot pressing furnace, and vacuum was applied to 0.05 Pa. The temperature was raised to 1150°C at a rate of 12°C / min, then a pressure of 30 MPa was applied, and the temperature was kept for 2 h to realize full diffusion bonding of the interface.

[0030] Step (5) directional solidification treatment: the hot-pressed composite blank was placed in a Bridgman-type directional solidification furnace, and directional solidification was carried out by zone melting method. The temperature gradient was controlled at 80°C / cm, the pulling speed was 10 μm / s, and the melting zone width was 12 mm. A static magnetic field of 0.3 T was applied to suppress the convection of the melt and obtain a flat liquid-solid interface.

[0031] Step (6) surface shot peening strengthening: a two-stage shot peening process was used: in the first stage, ZrO2 ceramic pellets with a diameter of 0.4 mm were used for rough peening at a speed of 150 m / s, with a coverage rate of 400%; in the second stage, Si3N4 ceramic pellets with a diameter of 0.15 mm were used for fine peening at a speed of 120 m / s, with a coverage rate of 150%, and the final surface roughness was controlled at Ra1.2 μm.

[0032] Performance test results: interface bonding strength (using shear test): 518 MPa; room temperature tensile properties: tensile strength 1250 MPa, elongation 16.2%; high temperature stress rupture life (at 1000°C / 150 MPa): increased by 48% compared with the same composition single nickel-based superalloy; creep rate at 1000°C / 100 MPa: 9.2×10⁻ 8 s⁻¹; metallographic observation showed that the interface diffusion layer thickness was 8-12 μm, and the average columnar crystal penetrated 3-4 material layers. Example 2

[0033] Step (1) Nickel-based superalloy sheet pretreatment: Nickel-based superalloy sheet with thickness of 1.5 mm, oxygen content of 42 ppm. Use water pressure of 450 MPa, nozzle diameter of 0.25 mm, etching depth of 0.6 mm (40% of plate thickness) trapezoidal groove, groove bottom angle of 65°, pitch of 2.5 mm (1.67 times of plate thickness), surface roughness Ra of 0.9 μm.

[0034] Step (2) Eutectic high-entropy alloy sheet pretreatment: Eutectic high-entropy alloy sheet with thickness of 1.5 mm, Ni content of 32.98 at% (deviation of -0.04 at%). Etch complementary protrusions, height tolerance of ±0.04 mm, surface roughness Ra of 0.8 μm.

[0035] Step (3) Alternating stack assembly: Stack 20 layers, preheat at 900 °C for 2 minutes after every 5 layers.

[0036] Step (4) Vacuum hot pressing composite: Vacuum degree of 0.03 Pa, temperature rise to 1180 °C at 13 °C / min, apply pressure of 40 MPa for 2 h, pre-plate Ni / Ti composite intermediate layer (Ni:Ti=3:1) with thickness of 35 nm at the interface by magnetron sputtering.

[0037] Step (5) Directional solidification treatment: Temperature gradient of 90 °C / cm, pulling speed of 8 μm / s, melting zone width of 14 mm, apply static magnetic field of 0.4 T.

[0038] Step (6) Surface shot peening: First stage: 0.45 mm shot, 180 m / s, coverage of 450%, second stage: 0.18 mm shot, 130 m / s, coverage of 180%, final surface roughness Ra of 1.0 μm.

[0039] Performance test results: Interface bonding strength: 558 MPa; room temperature tensile properties: tensile strength of 1320 MPa, elongation of 15.8%; high-temperature endurance life increased by 55%; creep rate: 7.8 x 10⁻ 8 s⁻¹; interface diffusion layer thickness: 10-15 μm, columnar crystals penetrate 4-5 layers. Example 3

[0040] Step (1) Nickel-based superalloy sheet pretreatment: Nickel-based superalloy sheet with thickness of 0.8 mm, oxygen content of 28 ppm, use water pressure of 380 MPa, nozzle diameter of 0.18 mm, etching depth of 0.32 mm (40% of plate thickness) trapezoidal groove, groove bottom angle of 72°, pitch of 1.4 mm (1.75 times of plate thickness), surface roughness Ra of 0.7 μm.

[0041] Step (2) Co-crystal high-entropy alloy sheet pretreatment: Co-crystal high-entropy alloy sheet with thickness of 0.8 mm, Ni content of 33.06 at% (deviation + 0.04 at%), etched complementary protrusions, height tolerance of ± 0.02 mm, surface roughness of Ra 0.6 μm were prepared.

[0042] Step (3) Alternating lamination assembly: 8 layers were stacked, and after every 4 layers, preheating was performed at 880 ℃ for 1.5 minutes.

[0043] Step (4) Vacuum hot-pressing compounding: vacuum degree of 0.08 Pa, temperature rise to 1120 ℃ at 14 ℃ / min, 25 MPa pressure was applied for 2.5 hours.

[0044] Step (5) Directional solidification treatment: temperature gradient of 60 ℃ / cm, pulling speed of 15 μm / s, melting zone width of 10 mm, 0.2T static magnetic field was applied.

[0045] Step (6) Surface shot peening strengthening: first stage: 0.35 mm shot, 160 m / s, coverage of 350%; second stage: 0.12 mm shot, 110 m / s, coverage of 120%, final surface roughness of Ra 0.9 μm.

[0046] Performance test results: interface bonding strength: 505 MPa; room temperature tensile properties: tensile strength of 1210 MPa, elongation of 16.8%; high-temperature endurance life increased by 42%; creep rate: 9.8×10⁻ 8 s⁻¹; interface diffusion layer thickness: 6-10 μm, columnar crystals penetrated 3 layers.

[0047] Comparative Example 1 (without mechanical interlocking structure) The same material and process parameters as in Example 1 were used, but no groove / protrusion processing was performed, and flat surfaces were directly used for lamination and hot-pressing compounding.

[0048] Test results: interface bonding strength: 225 MPa; room temperature tensile properties: tensile strength of 980 MPa, elongation of 12.5%; high-temperature endurance life increased by only 9%; creep rate: 3.2×10⁻ 7 s⁻¹; metallographic observation showed that there were obvious holes and cracks at the interface.

[0049] Comparative Example 2 (without directional solidification treatment) The same material and first four steps of process as in Example 1 were used, but the directional solidification treatment step was omitted, and shot peening was directly performed after hot-pressing. Test results: interface bonding strength: 385 MPa; room temperature tensile properties: tensile strength of 1100 MPa, elongation of 14.2%; high-temperature endurance life increased by 18%; creep rate: 2.1×10⁻ 7s"1, and the organization observation shows no columnar crystal throughout phenomenon.

[0050] Comparative Example 3 (without intermediate layer) The same process as Example 2 was used, but without prepositioning the Ni / Ti composite intermediate layer. Test results: interfacial bonding strength: 465 MPa; room temperature tensile properties: tensile strength 1250 MPa, elongation 15.2%; high temperature stress-rupture life increased by 42%; creep rate: 1.2 x 10"5s"1; interfacial diffusion layer thickness: 5-8 μm. 7 s"1; interfacial diffusion layer thickness: 5-8 μm.

[0051] The above examples are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A method for preparing a nickel-based superalloy / eutectic high-entropy alloy laminated composite, characterized in that, The method comprises the following steps: (1) Nickel-based superalloy sheet pretreatment: using cold isostatic pressing process to prepare nickel-based superalloy sheet with thickness of 0.5-2mm, using high-pressure water jet cutting technology (water pressure 300-500MPa, nozzle diameter 0.1-0.3mm) to etch trapezoidal grooves with depth of 30-50% of the sheet thickness on the surface, groove spacing is 1.5-2 times of the sheet thickness; (2) Eutectic high-entropy alloy sheet pretreatment: using the same cold isostatic pressing process to prepare eutectic high-entropy alloy sheet with matching thickness, using water jet cutting technology with the same parameters to etch protruding structures complementary to the groove shape of step (1), the protrusion height tolerance is controlled within ±0.05mm; (3) Alternating layer assembly: the grooved sheet prepared in steps (1) and (2) are alternately stacked in the order of "superalloy-high-entropy alloy", the grooves and protrusions between adjacent layers form a mechanical interlocking structure, the number of layers is 5-30; (4) Vacuum hot pressing compounding: placing the layer assembly in a vacuum hot pressing furnace, under a vacuum degree of 0.01-0.1Pa, heating to 1100-1200℃ at a rate of 10-15℃ / min, applying a pressure of 20-50MPa for 1-3h to realize interface diffusion bonding; (5) Directional solidification treatment: placing the hot-pressed composite blank into a directional solidification furnace, controlling the temperature gradient to be 50-100℃ / cm, and the pulling speed to be 5-20μm / s to obtain a composite material with columnar crystal structure; (6) Surface shot peening: using ceramic pellets with a diameter of 0.2-0.5mm to perform shot peening on the surface of the composite material at a speed of 100-200m / s, the coverage rate is 300-500%, and the surface roughness is controlled within Ra0.8-1.6μm.

2. The method of claim 1, wherein, The nickel-based superalloy sheet in step (1) has a composition of Ni-15Cr-8Co-5Mo-4W-3Al-2Ti-1Nb (wt%), and the oxygen content is ≤50ppm.

3. The method of claim 1, wherein, The composition of the eutectic high-entropy alloy sheet in step (2) is: AlCoCrFeNi 2.1 wherein the Ni content is controlled within ±0.05 at%.

4. The method of claim 1, wherein, The cross-sectional shape of the grooves and protrusions in steps (1) and (2) is an isosceles trapezoid with a base angle of 60-75°, and the surface roughness Ra is ≤1.0μm.

5. The method of claim 1, wherein, During the layer assembly process of step (3), preheating at 800-1000℃ for 1-3min is performed every 5 layers to eliminate accumulated stress.

6. The method of claim 1, wherein, During the hot pressing compounding process of step (4), a Ni / Ti composite intermediate layer with a thickness of 20-50nm is prepositioned at the interface.

7. The method of claim 1, wherein, The directional solidification of step (5) uses the zone melting method, the width of the melting zone is controlled within 10-15mm, and a static magnetic field of 0.1-0.5T is applied.

8. The method of claim 1, wherein, The shot peening of step (6) is performed in two stages: the first stage uses larger pellets (0.3-0.5mm) for rough peening, and the second stage uses smaller pellets (0.1-0.2mm) for fine peening.

9. The Ni-based superalloy / eutectic high-entropy alloy laminated composite prepared by any of the methods of claims 1-8, characterized in that: The interface bonding strength is ≥500MPa, and the high-temperature (1000℃) stress rupture life is increased by 40-60% compared to single nickel-based superalloy.

10. The composite material of claim 9, wherein: It has an alternating layered structure, the single layer thickness is 0.3-1.5mm, the interface diffusion layer thickness is 5-15μm, and the columnar crystal penetrates through 3-5 material layers.

11. The composite material of claim 9, wherein: Room temperature tensile strength ≥ 1200 MPa, elongation ≥ 15%, creep rate under 1000 °C / 100 MPa conditions ≤ 1 x 10 -7 s -1 .

12. Use of a composite material according to any one of claims 9 to 11 in an aeroengine turbine blade, a gas turbine hot section component or a nuclear reactor cladding material.

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