Cr / FeMoAlSiY composite material and preparation method thereof

Abstract

The invention discloses a Cr / FeMoAlSiY composite material and a preparation method, and belongs to the field of material surface modification.The Cr / FeMoAlSiY composite material comprises FeMoAlSiY layers and Cr layers which are alternately arranged in a stacked mode, heterostructures on the two sides of a heterogeneous interface between the Cr layers and the FeMoAlSiY layers are of a crystal structure and an amorphous structure, the FeMoAlSiY layers block continuous growth of the Cr layers, through coupling of the FeMoAlSiY layers and the crystal Cr layers, continuous growth of the Cr layers is blocked, and the Cr / FeMoAlSiY composite material is formed. According to the Cr / FeMoAlSiY composite material, the strain gradient is introduced at the heterogeneous interface, so that different mechanical responses of the heterogeneous structure are excited, and meanwhile, the heterogeneous interface serves as an effective dislocation well, so that the mechanical property and the thermal stability of the Cr / FeMoAlSiY composite material are improved. The Cr / FeMoAlSiY composite material has excellent comprehensive performance and good high temperature resistance, and is expected to be applied to the field of nuclear fuel cladding protective coatings.

Description

Technical Field

[0001] The present invention belongs to the field of metal surface modification, and particularly relates to a Cr / FeMoAlSiY composite material and a preparation method thereof. Background Art

[0002] Lead-bismuth eutectic (LBE) alloy has been selected as a potential coolant material for the fourth-generation fast neutron breeder reactor due to its excellent thermophysical, chemical, and neutron properties. However, the structural materials (steel materials) in direct contact with LBE will suffer from severe liquid metal corrosion (oxidation, dissolution, erosion, etc.) and liquid metal embrittlement, resulting in the failure of the structural materials and shortening the equipment life. During the process of liquid metal corrosion and liquid metal embrittlement of the structural materials, the microstructure, tissue composition, and surface morphology of the structural materials will all change, and their mechanical properties and physical and chemical properties will also change accordingly.

[0003] Protecting the structural materials with surface coatings can improve the LBE corrosion resistance of the structural materials without changing their inherent microstructure and mechanical properties; for example, ceramic coatings (oxides, carbides, and nitrides), single-metal coatings (refractory metals), and alloy coatings (including Fe-Cr-Al alloys). However, the main disadvantage of ceramic coatings is their inherent brittleness, which is prone to cracking and peeling under external loading and lacks self-healing ability after damage. The single-metal coatings made of refractory metals have a low solubility in liquid LBE, so the single-metal coatings have strong LBE dissolution corrosion, but due to the corresponding oxides being non-dense and unstable, the single-metal coatings have weak LBE oxidation corrosion resistance; alloy coatings are prone to generating a second-phase compound, especially brittle intermetallic compounds, during high-temperature service, resulting in an increase in the brittleness of the alloy coatings.

[0004] The performance improvement of existing surface coatings has tended to reach a bottleneck and it is difficult to meet the usage requirements of the fourth-generation fast neutron breeder reactor. Therefore, it is necessary to develop a new type of surface coating. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a Cr / FeMoAlSiY composite material and a preparation method thereof. By coupling the heterogeneous structure between the FeMoAlSiY layer and the Cr layer with the multi-principal element effect of the high-entropy alloy, a Cr / FeMoAlSiY composite material with uniform density and strong heterogeneous interface bonding force is formed, improving the comprehensive mechanical properties and thermal stability of the composite material.

[0006] The present invention is realized through the following technical solutions: A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: Clean the substrate to remove impurities and oxide films on the surface; Step 2: Perform vacuum etching on the substrate obtained in Step 1; Step 3: Use FeMoAlSiY target and Cr target to perform DC magnetron sputtering on the vacuum-etched substrate, alternately depositing FeMoAlSiY layer and Cr layer until reaching the predetermined thickness to obtain a layered composite material; During the DC magnetron sputtering process, first deposit the FeMoAlSiY layer, then deposit the Cr layer, and the last layer is the FeMoAlSiY layer. The deposition time of the FeMoAlSiY layer is 357 s - 1430 s, the deposition time of the Cr layer is 301 s - 1205 s, the number of modulation periods is 5 - 20, the deposition pressure is 0.3 - 1.0 Pa, and the predetermined thickness is 1.9 μm - 2.2 μm; Step 4: Cool the layered composite material to room temperature to obtain a Cr / FeMoAlSiY composite material.

[0007] Preferably, the method for cleaning the substrate to remove impurities and oxide films on the surface in Step 1 is as follows: Ultrasonically clean the substrate in acetone and ethanol in sequence, and then immerse the substrate in an aqueous hydrofluoric acid solution to remove the oxide film on the substrate surface.

[0008] Preferably, during the DC magnetron sputtering process in Step 3, the deposition temperature is room temperature, the gas flow rate is 25 - 70 sccm, and the substrate rotation speed is 10 r / min.

[0009] Preferably, the deposition thickness of the Cr layer and the FeMoAlSiY layer in each modulation period is 50 nm - 200 nm.

[0010] Preferably, the DC sputtering power of the FeMoAlSiY target and the Cr target is 200 W.

[0011] Preferably, the cooling time in Step 4 is 2 - 3 hours.

[0012] A Cr / FeMoAlSiY composite material prepared by a method for preparing a Cr / FeMoAlSiY composite material, including alternately arranged Cr layers and FeMoAlSiY layers, the thicknesses of the Cr layer and the FeMoAlSiY layer in each modulation period are the same, and the total thickness of the Cr / FeMoAlSiY composite material is 1.9 μm - 2.2 μm; The structure of the Cr layer is a crystal structure, the grain morphology is columnar crystal, and the structure of the FeMoAlSiY layer is an amorphous structure.

[0013] Preferably, a heterointerface is formed between the Cr layer and the FeMoAlSiY layer, and the two sides of the heterointerface are a crystal structure and an amorphous structure.

[0014] Preferably, the hardness of the Cr / FeMoAlSiY composite material is 5.53 GPa - 10.56 GPa.

[0015] A nuclear fuel cladding, on the surface of which the Cr / FeMoAlSiY composite material is provided.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: A Cr / FeMoAlSiY composite material provided by the present application includes an FeMoAlSiY layer and a Cr layer which are alternately stacked. The Cr element has excellent high-temperature oxidation resistance, corrosion resistance, and a low thermal neutron absorption cross section, etc. FeMoAlSiY is a high-entropy amorphous alloy, which combines the chemical composition characteristics of high-entropy alloys and the structural characteristics of amorphous alloys, and has excellent mechanical properties and yield strength. Elements such as Fe and Al in the high-entropy amorphous alloy can form an oxide film, making the Cr / FeMoAlSiY composite material have good corrosion resistance. In addition, a high-density heterointerface is formed between the Cr layer and the FeMoAlSiY layer, which restricts the rapid migration of interstitial atoms to the material surface, reduces the generation of vacancies, and promotes the re-emission of self-interstitial atoms at the heterointerface, annihilating the vacancies near the heterointerface and reducing the density of defects, thereby improving the mechanical properties and thermal stability of the Cr / FeMoAlSiY composite material.

[0017] The preparation method of the Cr / FeMoAlSiY composite material provided by the present application adjusts the thicknesses of the Cr layer and the FeMoAlSiY layer by controlling the deposition time, and simultaneously controls the grain size and the density of the hetero-interfaces; the atomic mobility is regulated by controlling the deposition pressure; during the deposition process, the large atomic radius mismatch, relatively large negative mixing enthalpy, and relatively low mixing entropy among the Fe atoms, Mo atoms, Al atoms, Si atoms, and Y atoms sputtered from the FeMoAlSiY target result in slow atomic diffusion in the matrix, low phase transformation rate, easy segregation of atoms in the alloy, poor crystallinity due to insufficient diffusion of elements in time, and high collision probability. The energy of the atoms deposited on the matrix is relatively large, so a metastable amorphous structure is formed; the Cr atoms sputtered from the Cr target are deposited to form a crystal structure. The Cr / FeMoAlSiY composite materials with different layer thicknesses are formed by deposition at different sputtering times, and the structures of the hetero-interfaces between the layers are all crystal and amorphous structures, and the hetero-interface structures are stable and do not change. The functional element thickness and the hetero-interfaces of the Cr / FeMoAlSiY composite material are important factors affecting the mechanical properties and deformation mechanism. The Cr layer is a crystal layer, and the FeMoAlSiY layer is an amorphous layer. Under the action of an external load, deformation mechanisms such as dislocations and grain boundaries in the crystal layer dominating deformation, shear transformation zones in the amorphous layer, and deformation dominated by localized shear bands are coupled through the hetero-interfaces. By controlling the deposition time, the density of the hetero-interfaces and the number of grain boundaries are regulated. The decrease in the layer thickness increases the density of the hetero-interfaces, greatly hindering the movement of dislocations in the Cr / FeMoAlSiY composite material and improving the strength of the Cr / FeMoAlSiY composite material to a certain extent. The influence of the layer thickness on the density of the hetero-interfaces results in non-uniform plastic deformation of the Cr / FeMoAlSiY composite material with a large layer thickness (above 100 nm) and uniform plastic deformation of the Cr / FeMoAlSiY composite material with a small layer thickness (below 100 nm) under the action of an external load.

[0018] Further, after the deposition is completed, it is naturally cooled in the vacuum coating chamber to room temperature in the furnace, and the cooling time is 2 - 3 hours, to avoid the Cr / FeMoAlSiY composite material falling off from the matrix under the action of internal stress due to the difference in the thermal expansion coefficients of the Cr / FeMoAlSiY composite material and the matrix, and to prevent the Cr / FeMoAlSiY composite material from contacting with air and oxidizing at high temperature, so that the deposited atoms are fully diffused to form the final dense and uniform Cr / FeMoAlSiY composite material. Description of the Drawings

[0019] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0020] Figure 1 Schematic diagrams of the structures of Cr / FeMoAlSiY composites with different layer thicknesses in Embodiments 1 to 6 of the present invention; Figure 2 XRD (X-Ray Diffraction) pattern of the Cr / FeMoAlSiY composite material of the present invention; Figure 3 TEM (Transmission Electron Microscope) cross-sectional view and EDS (Energy Dispersive Spectrometer) surface scan view of the Cr / FeMoAlSiY composite material with a total thickness of 2.2 μm prepared by the present invention; Figure 4 TEM cross-sectional view and EDS surface scan view of the Cr / FeMoAlSiY composite material with a total thickness of 1.95 μm prepared by the present invention; Figure 5 TEM cross-sectional view and EDS surface scan view of the Cr / FeMoAlSiY composite material with a total thickness of 2.1 μm prepared by the present invention; Figure 6 TEM cross-sectional view and EDS surface scan view of the Cr / FeMoAlSiY composite material with a total thickness of 2.05 μm prepared by the present invention; Figure 7 TEM cross-sectional view of the Cr / FeMoAlSiY composite material prepared at a pressure of 0.7 Pa by the present invention; Figure 8 TEM cross-sectional view of the Cr / FeMoAlSiY composite material prepared at a pressure of 0.3 Pa by the present invention; Figure 9 TEM cross-sectional view and STEM (Scanning Transmission Electron Microscopy) cross-sectional view of the Cr / FeMoAlSiY composite material of the present invention after annealing at 650 °C; Figure 10This is the nano-indentation hardness diagram of the as-deposited Cr / FeMoAlSiY composites with different layer thicknesses of the present invention and after annealing at 500 °C and 650 °C. GPa is the unit of hardness in gigapascals. Detailed implementation manners

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. Usually, the components of the embodiments of this application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application that is claimed, but merely represents selected embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0023] A Cr / FeMoAlSiY composite material of this application includes a Cr layer and a FeMoAlSiY layer. The Cr layer is a crystal layer, and the FeMoAlSiY layer is an amorphous layer.

[0024] This FeMoAlSiY is a high-entropy amorphous alloy, which combines the characteristics of multi-principal element components of high-entropy alloys and the disordered alloy characteristics formed by the long-range disorder and short-range order of amorphous alloys. High-entropy alloys are composed of five or more elements in equimolar ratio or approximate equimolar ratio. Since high-entropy amorphous alloys combine the characteristics of high-entropy alloys and amorphous alloys, high-entropy amorphous alloys exhibit unique mechanical, chemical, and physical properties, such as high strength, high fracture toughness, large elastic strain limit, excellent corrosion resistance, and excellent soft magnetic properties, etc. The FeMoAlSiY high-entropy amorphous alloy is used as the amorphous layer of the Cr / FeMoAlSiY composite material.

[0025] Under tensile load, high-entropy amorphous alloys are prone to brittle fracture of the material instantaneously due to the expansion of shear bands. Introducing any crystal phase into high-entropy amorphous alloys can inhibit highly localized shear bands, thereby exerting a constraint effect on the fracture of the surface coating, and significantly improving the overall plasticity of the surface coating by forming multiple shear bands. This constraint effect is particularly prominent at the heterointerface of crystal / amorphous multilayers. In the multilayer film, each amorphous layer is sandwiched between two adjacent crystal layers and is highly constrained. Since Cr metal has good mechanical properties and corrosion resistance, Cr metal is used as the crystal phase and introduced as an element of the crystal layer in the Cr / FeMoAlSiY composite material.

[0026] A Cr / FeMoAlSiY composite material includes alternately arranged Cr layers and FeMoAlSiY layers. The thicknesses of the Cr layers and FeMoAlSiY layers in each modulation period are the same, and the total thickness of the Cr / FeMoAlSiY composite material is 1.9 μm - 2.2 μm.

[0027] The structure of the Cr layer is a crystal structure, and the grain morphology is columnar crystals. The structure of the FeMoAlSiY layer is a uniform and dense amorphous structure.

[0028] In FeMoAlSiY, Fe and Al elements can form a dense oxide film, and Mo, Si, and Y elements inhibit the interdiffusion of Fe element and the structural material. At the same time, based on the phase formation criterion: the relationship between phase composition and mixing enthalpy, mixing entropy, and atomic radius difference, the atomic percentage of this FeMoAlSiY is 45:17:17:18.5:2.5.

[0029] This Cr / FeMoAlSiY composite material is composed of multiple alternately stacked Cr layers and FeMoAlSiY layers, forming a unique layered structure and a high-density heterogeneous interface. During the deformation process, due to the different strengths between the amorphous structure and the crystal structure, stress redistribution will occur to produce coordinated deformation, thereby introducing a strain gradient at the heterogeneous interface, stimulating different mechanical responses of the heterogeneous interface, and generating geometrically necessary dislocations at the heterogeneous interface, resulting in the heterogeneous deformation-induced hardening effect. At the same time, the heterogeneous interface serves as an effective dislocation trap, showing a unique inelastic shear slip characteristic, that is, good strain compatibility, during the plastic deformation process, thereby eliminating stress concentration. Based on the above effects, the mechanical properties of the Cr / FeMoAlSiY composite material are improved. The size of this Cr / FeMoAlSiY composite material is stable in the nanocrystalline range. This Cr / FeMoAlSiY composite material has a dense structure, good plastic deformation ability, excellent mechanical properties, and good thermal stability. The structure and mechanical properties of the heterogeneous interface are enhanced as the layer thickness decreases. The hardness of this Cr / FeMoAlSiY composite material is 5.53 GPa - 10.56 GPa.

[0030] Correspondingly, the present application also provides a preparation method for the above-mentioned Cr / FeMoAlSiY composite material, including the following steps: Step 1: Clean and dry the substrate, and remove the oxide film on the surface of the substrate.

[0031] Specifically, polish one side of the substrate, then ultrasonically clean the polished substrate in acetone and ethanol for at least 15 min in sequence, and then quickly dry it with warm air to make the surface of the substrate clean without stains and dust attachment, and the roughness is below 0.8 - 1.5 nm.

[0032] Immerse the dried substrate in an aqueous hydrofluoric acid solution for at least 5 min to remove the oxide film on the substrate surface, and then dry it. The concentration of the aqueous hydrofluoric acid solution is 40 wt.% - 45 wt.%.

[0033] The substrate is a silicon substrate.

[0034] Step 2: Perform vacuum etching on the substrate obtained in Step 1.

[0035] Fix the substrate obtained in Step 1 to the substrate holder with conductive adhesive, mechanically transfer it into the coating chamber, evacuate to below 4.0×10 -4 Pa, and use Ar + ions to etch the substrate to further remove impurities on the substrate surface.

[0036] Ar + The power of Ar ion etching is 200 W, and the etching time is at least 5 min.

[0037] Step 3: Use FeMoAlSiY target and Cr target to alternately deposit FeMoAlSiY layer and Cr layer on the substrate obtained in Step 2 by DC magnetron sputtering to obtain a layered composite material. The thickness of the layered composite material is 1.9 μm - 2.2 μm, and the deposition thicknesses of the Cr layer and FeMoAlSiY layer in each modulation period are equal.

[0038] During the DC magnetron sputtering process, the powers of both the FeMoAlSiY target and the Cr target are 200 W. The purity of the Cr target is not less than 99.99 wt.%; the purity of the FeMoAlSiY target is not less than 99.95 wt.%.

[0039] The substrate rotation speed is 10 r / min, the Ar gas flow rate is set to 25 - 70 sccm, the deposition pressure is 0.3 Pa - 1.0 Pa, and the deposition temperature is room temperature; the deposition time of the FeMoAlSiY layer is 357 s - 1430 s, the deposition time of the Cr layer is 301 s - 1205 s, the total deposition time is 14000 - 15000 s, and the number of modulation periods is 5 - 20.

[0040] During the DC magnetron sputtering process, pre-sputtering and formal sputtering are carried out in sequence. The argon gas introduction time before pre-sputtering is at least 30 s; the pre-sputtering time is at least 10 s.

[0041] Step 4: Cool the layered composite material to room temperature to obtain a Cr / FeMoAlSiY composite material.

[0042] Specifically, the layered composite material is naturally cooled in the vacuum coating chamber for 2 - 3 hours to room temperature and then taken out to obtain a Cr / FeMoAlSiY composite material.

[0043] As shown Figure 1 in the figure, the Cr / FeMoAlSiY composite material prepared by this preparation method includes an FeMoAlSiY layer and a Cr layer provided on a substrate. The FeMoAlSiY layer and the Cr layer are alternately stacked. The uppermost layer of the Cr / FeMoAlSiY composite material is the FeMoAlSiY layer. A heterointerface is formed between the Cr layer and the FeMoAlSiY layer. The atomic ratio in the FeMoAlSiY layer is Fe:Mo:Al:Si:Y = 45:17:17:18.5:2.5.

[0044] As shown Figure 2 in the figure, the XRD patterns of the Cr / FeMoAlSiY composite material all exhibit a body-centered cubic crystal structure with a preferred orientation of Cr(110), and diffraction peaks with very weak intensities of Cr(200) and Cr(211) orientations. The FeMoAlSiY layer is an amorphous layer and does not show crystal diffraction peaks. As a crystal layer, the Cr layer has a columnar crystal grain morphology, and the grain size is stably maintained within the nanocrystalline range. As the layer thickness h gradually decreases, the grain size shows a monotonically decreasing trend. When the layer thickness of the Cr layer decreases, the columnar crystals grow continuously along the deposition direction and are effectively confined within the layer, forming a highly ordered crystal structure. In addition, the Cr / FeMoAlSiY composite material also has excellent mechanical properties such as high strength and good plastic deformation ability.

[0045] Figure 2 In the figure, Intensity (a.u.) represents the strength of the Raman signal, a.u. (arbitrary units) represents arbitrary units, and degree is the diffraction angle.

[0046] Example 1 A preparation method of a Cr / FeMoAlSiY composite material includes the following steps: Step 1: Ultrasonically clean the polished silicon substrate on one side in pure acetone and ethanol for 15 min to remove surface impurities on the silicon substrate, and then quickly dry it with warm air; subsequently, immerse the silicon substrate in a 41 wt.% hydrofluoric acid aqueous solution for 5 min, and quickly dry it after removing the surface oxide film of the silicon substrate.

[0047] Step 2: Fix the silicon substrate on the substrate plate with conductive glue, and mechanically and automatically send it into the magnetron sputtering vacuum coating chamber. The background vacuum degree is 4.0×10 -4 Pa, and then perform Ar + ion etching. The etching power is 200 W, and the etching time is 5 min.

[0048] Step 3: Use DC magnetron sputtering technology to alternately deposit FeMoAlSiY layers and Cr layers on the etched silicon substrate to obtain a layered composite material; During the deposition process, turn on the FeMoAlSiY target and the Cr target in sequence to alternately deposit FeMoAlSiY layers and Cr layers with equal layer thickness. The last layer is the FeMoAlSiY layer, that is, the surface layer of the Cr / FeMoAlSiY composite material. The DC power of the FeMoAlSiY target is 200 W, and the DC power of the Cr target is 200 W.

[0049] The deposition time of the FeMoAlSiY layer is 1430 s, the deposition time of the Cr layer is 1205 s, the number of modulation periods is 5, the deposition pressure is set at 1.0 Pa, the Ar gas flow rate is 70 sccm, the deposition temperature is room temperature, and the substrate rotation speed is 10 r / min.

[0050] Step 4: Naturally cool the layered composite material to room temperature in a high-vacuum coating chamber. The cooling time is 2 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness h of 200 nm and a total thickness of 2.2 μm.

[0051] Perform microstructure characterization, mechanical property testing, and high-temperature oxidation resistance testing on the Cr / FeMoAlSiY composite material prepared in this example. As Figure 3 shown, the longitudinal section of the Cr / FeMoAlSiY composite material shows an obvious multi-layer modulation structure. The grains of the Cr layer show a columnar crystal structure, the FeMoAlSiY layer is an amorphous structure, and the thickness of each layer is equal. The columnar crystal grain size is about 40 ± 9.79 nm. The heterointerface is between the crystal layer and the amorphous layer, and there are no obvious holes or cracks at the heterointerface junction, indicating that the crystal layer and the amorphous layer are well combined. It can be seen from the EDS diagram that the heterointerface is smooth and straight, and there is no obvious element diffusion phenomenon.

[0052] Figure 3 The first picture in the first row in

[0053] is a low-magnification transmission electron microscope cross-sectional view with a scale of 200 nm and an electron diffraction pattern in the reciprocal space with a scale of 5 1 / nm. The second picture is a high-magnification transmission electron microscope cross-sectional view with a scale of 10 nm. The third picture is a bright-field transmission electron microscope cross-sectional view with a scale of 500 nm.

[0054] The Cr / FeMoAlSiY composite materials were annealed at 500 °C and 650 °C for 2 h respectively. The Cr / FeMoAlSiY composite material annealed at 500 °C was nano-indentated under a load of 9000 μN, and its hardness was measured to be 6.58 GPa; the Cr / FeMoAlSiY composite material annealed at 650 °C was nano-indentated under a load of 9000 μN, and its hardness was measured to be 6.97 GPa.

[0055] Example 2 A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: The polished silicon substrate on one side was ultrasonically cleaned in pure acetone and ethanol for 15 min in sequence to remove the surface impurities of the silicon substrate, and then quickly dried with warm air; subsequently, the silicon substrate was immersed in a 42 wt.% hydrofluoric acid aqueous solution for 5 min, and after removing the surface oxide film of the silicon substrate, it was quickly dried.

[0056] Step 2: The silicon substrate was fixed on the substrate with conductive glue and mechanically automatically sent into the magnetron sputtering vacuum coating chamber. The background vacuum degree was 4.0×10 -4 Pa, and then Ar + ion etching was carried out. The etching power was 200 W and the etching time was 5 min.

[0057] Step 3: The FeMoAlSiY layer and the Cr layer were alternately deposited on the etched silicon substrate by DC magnetron sputtering technology to obtain a layered composite material; During the deposition process, the FeMoAlSiY target and the Cr target were sequentially turned on to alternately deposit the FeMoAlSiY layer and the Cr layer with equal layer thickness. First, the FeMoAlSiY layer was deposited, then the Cr layer was deposited, and the last layer was the FeMoAlSiY layer. The DC power of the FeMoAlSiY target was 200 W, and the DC power of the Cr target was 200 W.

[0058] The deposition time of the FeMoAlSiY layer was 1070 s, the deposition time of the Cr layer was 905 s, the number of modulation periods was 6, the deposition pressure was set at 1.0 Pa, the Ar gas flow rate was 70 sccm, the deposition temperature was room temperature, and the substrate rotation speed was 10 r / min.

[0059] Step 4: The layered composite material was naturally cooled to room temperature in a high-vacuum coating chamber, and the cooling time was 2.5 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness of 150 nm and a total thickness of 1.95 μm.

[0060] The Cr / FeMoAlSiY composite material of this example was subjected to microstructure characterization, mechanical property testing and high-temperature oxidation resistance testing, such as Figure 4As shown, the longitudinal section of the Cr / FeMoAlSiY composite material exhibits an obvious multi-layer modulation structure. The grains of the Cr layer show a columnar crystal structure, and the continuous growth of the columnar crystals is blocked by the FeMoAlSiY amorphous layer. The grain size is about 42 ± 10.23 nm. The heterogeneous interface is the interface between the crystalline Cr layer and the FeMoAlSiY high-entropy amorphous layer, and the crystallographic feature is the crystal / amorphous interface. There are no obvious pores or cracks at the junction of the heterogeneous interface, and the crystal layer and the amorphous layer are well combined. It can be seen from the EDS diagram that the heterogeneous interface is smooth and straight, and there is no obvious element diffusion phenomenon.

[0061] The Cr / FeMoAlSiY composite material was subjected to nano-indentation under a load of 9000 μN, and its hardness was measured to be 5.53 ± 0.12 GPa.

[0062] The Cr / FeMoAlSiY composite material was annealed and held for 2 h at 500 °C and 650 °C respectively; the Cr / FeMoAlSiY composite material annealed at 500 °C was subjected to nano-indentation under a load of 9000 μN, and its hardness was measured to be 6.31 GPa; the Cr / FeMoAlSiY composite material annealed at 650 °C was subjected to nano-indentation under a load of 9000 μN, and its hardness was measured to be 6.88 GPa.

[0063] Example 3 A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: The single-sided polished silicon substrate was ultrasonically cleaned in pure acetone and ethanol for 15 min in sequence to remove the surface impurities of the silicon substrate, and then quickly dried with warm air; subsequently, the silicon substrate was immersed in a 45 wt.% hydrofluoric acid aqueous solution for 5 min, and after removing the surface oxide film of the silicon substrate, it was quickly dried.

[0064] Step 2: The silicon substrate was fixed on the substrate plate with conductive glue and mechanically automatically fed into the magnetron sputtering vacuum coating chamber. The background vacuum degree was 4.0×10 -4 Pa, and then Ar + ion etching was carried out. The etching power was 200 W and the time was 5 min.

[0065] Step 3: The FeMoAlSiY layer and the Cr layer were alternately deposited on the etched silicon substrate by DC magnetron sputtering technology to obtain a layered composite material; During the deposition process, the FeMoAlSiY target and the Cr target were sequentially turned on to alternately deposit the FeMoAlSiY layer and the Cr layer with equal thickness. First, the FeMoAlSiY layer was deposited, then the Cr layer was deposited, and the last layer was the FeMoAlSiY layer. The DC power of the FeMoAlSiY target was 200 W, and the DC power of the Cr target was 200 W.

[0066] The deposition time of the FeMoAlSiY layer is 715 s, the deposition time of the Cr layer is 603 s, the number of modulation periods is 10, the deposition pressure is set at 1.0 Pa, the Ar gas flow rate is 70 sccm, the deposition temperature is room temperature, and the substrate rotation speed is 10 r / min.

[0067] Step 4: Naturally cool the laminated composite material to room temperature in a high-vacuum coating chamber for 3 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness of 100 nm and a total thickness of 2.1 μm.

[0068] Perform microstructure characterization, mechanical property testing, and high-temperature oxidation resistance testing on the Cr / FeMoAlSiY composite material prepared in this example, as Figure 5 shown. The grains of the Cr layer exhibit a columnar crystal structure, and at the same time, a nanocrystalline structure appears. The size of the columnar crystal grains is approximately 34 ± 7.96 nm, and the FeMoAlSiY layer is a dense amorphous structure. A heterointerface is formed between the Cr layer and the FeMoAlSiY layer, and there are no obvious holes or cracks at the heterointerface junction. The Cr layer and the FeMoAlSiY layer are well bonded. Figure 5 The Fourier transform diagram of the RI region in the transmission electron microscope image shows the amorphous halo of the amorphous layer, and the RII region shows the BCC diffraction spots of the Cr layer. It can be seen from the EDS diagram that the heterointerface is smooth and straight, and there is no obvious element diffusion phenomenon.

[0069] Figure 5 The first picture in the first row in is a low-magnification transmission electron microscope cross-sectional image with a scale of 200 nm and an electron diffraction image in the reciprocal space with a scale of 5 1 / nm. The second picture is a high-magnification transmission electron microscope cross-sectional image with a scale of 5 nm, and the third picture is a bright-field transmission electron microscope cross-sectional image with a scale of 200 nm.

[0070] Perform nanoindentation on the Cr / FeMoAlSiY composite material under a load of 9000 μN, and measure its hardness to be 5.58 ± 0.15 GPa.

[0071] Anneal and hold the Cr / FeMoAlSiY composite material at 500 °C and 650 °C for 2 h respectively; perform nanoindentation on the Cr / FeMoAlSiY composite material after annealing at 500 °C under a load of 9000 μN, and measure its hardness to be 6.10 GPa; perform nanoindentation on the Cr / FeMoAlSiY composite material after annealing at 650 °C under a load of 9000 μN, and measure its hardness to be 6.65 GPa.

[0072] Example 4 A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: Ultrasonically clean the polished single-sided silicon substrate in pure acetone and ethanol for 15 min in sequence to remove the surface impurities of the silicon substrate, and then quickly dry it with warm air; subsequently, immerse the silicon substrate in an aqueous hydrofluoric acid solution with a concentration of 45 wt.% for 5 min, and quickly dry it after removing the surface oxide film of the silicon substrate.

[0073] Step 2: Fix the silicon substrate on the substrate plate with conductive adhesive, and mechanically and automatically send it into the magnetron sputtering vacuum coating chamber. The background vacuum degree is 4.0×10 -4 Pa, and then perform Ar + ion etching. The etching power is 200 W and the time is 5 min.

[0074] Step 3: Alternately deposit FeMoAlSiY layer and Cr layer on the etched silicon substrate by DC magnetron sputtering technology to obtain a layered composite material; During the deposition process, turn on the FeMoAlSiY target and Cr target in sequence to alternately deposit FeMoAlSiY layer and Cr layer with equal layer thickness. First deposit the FeMoAlSiY layer, then deposit the Cr layer, and the last layer is the FeMoAlSiY layer. The DC power of the FeMoAlSiY target is 200 W, and the DC power of the Cr target is 200 W.

[0075] The deposition time of the FeMoAlSiY layer is 357 s, the deposition time of the Cr layer is 301 s, the number of modulation periods is 20, the deposition pressure is set at 1.0 Pa, the Ar gas flow rate is 70 sccm, the deposition temperature is room temperature, and the substrate plate rotation speed is 10 r / min.

[0076] Step 4: Naturally cool the layered composite material to room temperature in the high-vacuum coating chamber. The cooling time is 2 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness of 50 nm and a total thickness of 2.05 μm.

[0077] Perform microstructure characterization, mechanical property testing and high-temperature oxidation resistance testing on the Cr / FeMoAlSiY composite material prepared in this example. As Figure 6 shown, there is a heterogeneous interface between the Cr layer and the FeMoAlSiY layer. There are no obvious pores and cracks at the heterogeneous interface junction. The Cr layer and the FeMoAlSiY layer are well combined. It can be seen from the EDS diagram that there is a small amount of diffusion phenomenon at the heterogeneous interface. Due to the action of internal stress, the heterogeneous interface shows a certain degree of bending. Figure 6The Fourier transform pattern of the RI region in the high-resolution transmission electron microscopy image shows the BCC diffraction spots of the Cr layer, and the RII region shows the amorphous halo of the amorphous layer. The grains in the Cr layer exhibit a columnar crystal structure, and the columnar crystal grain size is approximately 27 ± 4.68 nm. At the same time, a large number of fine nanocrystals and a small amount of amorphous regions caused by element diffusion appear in the Cr layer. A large number of fine nanocrystals in the Cr layer are dispersed in a small amount of amorphous regions, which is equivalent to dispersion strengthening. A large number of grain boundaries are generated by the fine nanocrystals. At the same time h when = 50 nm, the interface density of the layer increases, so the density of the heterogeneous interface of the Cr / FeMoAlSiY composite material increases. The hardness measured by nanoindentation under a load of 9000 μN is 6.17 ± 0.16 GPa, which is the maximum hardness value of the Cr / FeMoAlSiY composite material prepared under a pressure of 1.0 Pa; As Figure 9 shown, after holding at 650 °C for 2 h, the Cr / FeMoAlSiY composite material still maintains a clear and complete modulated structure. The FeMoAlSiY layer remains a dense amorphous structure, and no crystallization phenomenon occurs. Grain growth induced by thermal stress appears in the Cr layer, and the grain size slightly increases to approximately 43 ± 6.12 nm. The grains in the Cr layer are still blocked by the amorphous layer and the layer thickness is equal. The Fourier transform pattern of the RI region in the high-resolution transmission electron microscopy image shows that the Cr layer still has BCC diffraction spots and no phase transformation occurs; the Fourier transform pattern of the amorphous layer in the RII region still shows an amorphous halo and no crystallization spots appear. After annealing and holding at 500 °C and 650 °C for 2 h, the hardness measured by nanoindentation of the samples under a load of 9000 μN is 6.52 GPa and 6.90 GPa respectively.

[0078] Example 5 A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: Ultrasonically clean the single-sided polished silicon substrate in pure acetone and ethanol for 15 min respectively to remove the surface impurities of the silicon substrate, and then quickly dry it with warm air; subsequently, immerse the silicon substrate in a 45 wt.% hydrofluoric acid aqueous solution for 5 min to remove the surface oxide film of the silicon substrate and then quickly dry it.

[0079] Step 2: Fix the silicon substrate on the substrate plate with conductive glue, and mechanically and automatically send it into the magnetron sputtering vacuum coating chamber. The background vacuum degree is 4.0×10 -4 Pa, and then perform Ar + ion etching. The etching power is 200 W and the time is 5 min.

[0080] Step 3: Use the direct current magnetron sputtering technology to alternately deposit the FeMoAlSiY layer and the Cr layer on the etched silicon substrate to obtain a layered composite material; During the deposition process, the FeMoAlSiY target and the Cr target are sequentially turned on to alternately deposit FeMoAlSiY layers and Cr layers with equal layer thickness. First, the FeMoAlSiY layer is deposited, then the Cr layer is deposited, and the last layer is the FeMoAlSiY layer. The DC power of the FeMoAlSiY target is 200 W, and the DC power of the Cr target is 200 W.

[0081] The deposition time of the FeMoAlSiY layer is 375 s, the deposition time of the Cr layer is 326 s, the number of modulation cycles is 20, the deposition pressure is set at 0.7 Pa, the Ar gas flow rate is 50 sccm, the deposition temperature is room temperature, and the substrate rotation speed is 10 r / min.

[0082] Step 4: Naturally cool the layered composite material to room temperature in a high-vacuum coating chamber. The cooling time is 2 - 3 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness of 50 nm and a total thickness of 2.05 μm.

[0083] The Cr / FeMoAlSiY composite material prepared in this example is subjected to microstructure characterization, mechanical property testing, and high-temperature oxidation resistance testing. As Figure 7 shown, the grains of the Cr layer exhibit a columnar crystal structure, and at the same time, a nanocrystalline structure appears. The size of the columnar crystal grains is about 21 ± 7.96 nm, and the FeMoAlSiY layer is a dense amorphous structure. The Fourier transform pattern of the RI region in the high-resolution transmission electron microscopy image shows the BCC diffraction spots of the Cr layer, and the RII region shows the amorphous halo of the amorphous layer. A heterogeneous interface is formed between the Cr layer and the FeMoAlSiY layer, and no obvious pores or cracks are generated at the junction of the heterogeneous interface. The Cr layer and the FeMoAlSiY layer are well combined. It can be seen from the EDS image that the heterogeneous interface is smooth and straight, and there is no obvious element diffusion phenomenon.

[0084] The Cr / FeMoAlSiY composite material is subjected to nanoindentation under a load of 9000 μN, and its hardness is measured to be 8.49 ± 0.19 GPa.

[0085] The Cr / FeMoAlSiY composite material is annealed and held at 500 °C and 650 °C for 2 h respectively; the Cr / FeMoAlSiY composite material after annealing at 500 °C is subjected to nanoindentation under a load of 9000 μN, and its hardness is measured to be 9.68 GPa; the Cr / FeMoAlSiY composite material after annealing at 650 °C is subjected to nanoindentation under a load of 9000 μN, and its hardness is measured to be 10.44 GPa.

[0086] Example 6 A preparation method of a Cr / FeMoAlSiY composite material, comprising the following steps: Step 1: The single-sided polished silicon substrate was ultrasonically cleaned in pure acetone and ethanol for 15 min successively to remove the surface impurities of the silicon substrate, and then quickly dried with warm air; subsequently, the silicon substrate was immersed in an aqueous hydrofluoric acid solution with a concentration of 45 wt.% for 5 min, and after removing the surface oxide film of the silicon substrate, it was quickly dried.

[0087] Step 2: The silicon substrate was fixed on the substrate holder with conductive adhesive and mechanically automatically fed into the magnetron sputtering vacuum coating chamber. The background vacuum degree was 4.0×10 -4 Pa, and then Ar + ion etching was carried out. The etching power was 200 W and the time was 5 min.

[0088] Step 3: The FeMoAlSiY layer and the Cr layer were alternately deposited on the etched silicon substrate by DC magnetron sputtering technology to obtain a layered composite material; During the deposition process, the FeMoAlSiY target and the Cr target were sequentially turned on to alternately deposit the FeMoAlSiY layer and the Cr layer with equal layer thickness. First, the FeMoAlSiY layer was deposited, then the Cr layer was deposited, and the last layer was the FeMoAlSiY layer. The DC power of the FeMoAlSiY target was 200 W, and the DC power of the Cr target was 200 W.

[0089] The deposition time of the FeMoAlSiY layer was 196 s, the deposition time of the Cr layer was 182 s, the number of modulation periods was 40, the deposition pressure was set at 0.3 Pa, the Ar gas flow rate was 25 sccm, the deposition temperature was room temperature, and the substrate holder rotation speed was 10 r / min.

[0090] Step 4: The layered composite material was naturally cooled to room temperature in the high-vacuum coating chamber, and the cooling time was 3 hours to obtain a Cr / FeMoAlSiY composite material with a layer thickness of 25 nm and a total thickness of 2.025 μm.

[0091] The microstructure characterization, mechanical property testing and high-temperature oxidation resistance testing were carried out on the Cr / FeMoAlSiY composite material prepared in this example. As Figure 8 shown, the grains of the Cr layer presented a columnar crystal structure, and the columnar crystal grain size was about 11±6.96 nm. The FeMoAlSiY layer was a dense amorphous structure. The hindrance of the amorphous layer to the continuous columnar crystals was reduced, and there were continuous columnar crystals growing through the crystal / amorphous interface. A heterogeneous interface was formed between the Cr layer and the FeMoAlSiY layer, and there were no obvious pores or cracks at the heterogeneous interface junction. The Cr layer and the FeMoAlSiY layer were well combined. Figure 8 The low-magnification transmission electron microscope cross-sectional view with a scale of 100 nm in

[0092] At a deposition pressure of 0.3 Pa, the atomic mobility increases, and the atoms diffuse sufficiently over a long distance, resulting in the formation of a dense structure. Coupled with the increased density of hetero-interfaces under a small layer thickness, when the Cr / FeMoAlSiY composite material is nano-indentated under a load of 9000 μN, its hardness is measured to be 10.56 ± 0.41 GPa, which is the maximum value of the hardness of the Cr / FeMoAlSiY composite materials prepared in each example.

[0093] The Cr / FeMoAlSiY composite materials are annealed and held at 500 °C and 650 °C for 2 h respectively; the Cr / FeMoAlSiY composite material annealed at 500 °C is nano-indentated under a load of 9000 μN, and its hardness is measured to be 10.65 GPa; the Cr / FeMoAlSiY composite material annealed at 650 °C is nano-indentated under a load of 9000 μN, and its hardness is measured to be 12.26 GPa.

[0094] A nuclear fuel cladding, the surface of which is the Cr / FeMoAlSiY composite material prepared by the preparation method of any one of the above examples.

[0095] A Cr / FeMoAlSiY composite material provided by the present application, the Cr layer is a crystal layer, and the FeMoAlSiY layer is an amorphous layer. By controlling the deposition time, the grain size of the Cr layer and the density of hetero-interfaces are controlled, so as to achieve the purpose of controlling the mechanical properties of the Cr / FeMoAlSiY composite material. The hetero-structure of the hetero-interface of the Cr / FeMoAlSiY composite material is a crystal and amorphous structure, and the amorphous FeMoAlSiY layer blocks the continuous growth of the Cr crystal layer. Through the coupling of the amorphous layer and the crystal layer, a strain gradient is introduced at the hetero-interface, thereby exciting different mechanical responses of the hetero-structure. At the same time, the hetero-interface serves as an effective dislocation trap, resulting in a breakthrough in mechanical properties and thermal stability. The present invention uses magnetron sputtering for sequential deposition, with a high ionization rate and a fast deposition rate. The deposition is carried out at room temperature and the generated working temperature is low, which is not easy to cause agglomeration and back-sputtering of target elements, and the microstructure is uniform and dense.

[0096] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a Cr / FeMoAlSiY composite material, characterized in that, It includes the following steps: Step 1: Clean the substrate to remove impurities and oxide films on the surface; Step 2: Perform vacuum etching on the substrate obtained in Step 1; Step 3: Use FeMoAlSiY target and Cr target to perform DC magnetron sputtering on the vacuum-etched substrate, alternately depositing FeMoAlSiY layer and Cr layer until reaching a predetermined thickness to obtain a laminated composite material; During the DC magnetron sputtering process, the FeMoAlSiY layer is deposited first, followed by the Cr layer, and the last layer is the FeMoAlSiY layer. The deposition time of the FeMoAlSiY layer is 357 s - 1430 s, the deposition time of the Cr layer is 301 s - 1205 s, the number of modulation periods is 5 - 20, the deposition pressure is 0.3 - 1.0 Pa, and the predetermined thickness is 1.9 μm - 2.2 μm; Step 4: Cool the laminated composite material to room temperature to obtain a Cr / FeMoAlSiY composite material.

2. The preparation method of a Cr / FeMoAlSiY composite material according to claim 1, characterized in that, The method for cleaning the substrate to remove impurities and oxide films on the surface in Step 1 is as follows: The substrate is ultrasonically cleaned in acetone and ethanol in sequence, and then the substrate is immersed in an aqueous hydrofluoric acid solution to remove the oxide film on the substrate surface.

3. The preparation method of a Cr / FeMoAlSiY composite material according to claim 1, characterized in that, During the DC magnetron sputtering process in Step 3, the deposition temperature is room temperature, the gas flow rate is 25 - 70 sccm, and the substrate rotation speed is 10 r / min.

4. The preparation method of a Cr / FeMoAlSiY composite material according to claim 1, characterized in that, The deposition thickness of the Cr layer and the FeMoAlSiY layer in each modulation period is 50 nm - 200 nm.

5. The preparation method of a Cr / FeMoAlSiY composite material according to claim 1, characterized in that, The DC sputtering power of the FeMoAlSiY target and the Cr target is 200 W.

6. The preparation method of a Cr / FeMoAlSiY composite material according to claim 1, characterized in that, The cooling time in Step 4 is 2 - 3 hours.

7. A Cr / FeMoAlSiY composite material prepared by the preparation method of the Cr / FeMoAlSiY composite material according to any one of claims 1-6, characterized in that, It includes alternately arranged FeMoAlSiY layers and Cr layers. The thicknesses of the Cr layer and the FeMoAlSiY layer in each modulation period are the same, and the total thickness of the Cr / FeMoAlSiY composite material is 1.9 μm - 2.2 μm; The structure of the Cr layer is a crystal structure, and the grain morphology is columnar crystals. The structure of the FeMoAlSiY layer is an amorphous structure.

8. A Cr / FeMoAlSiY composite material prepared by the preparation method of a Cr / FeMoAlSiY composite material according to claim 7, characterized in that, Between the Cr layer and the FeMoAlSiY layer is a heterointerface, and the two sides of this heterointerface are crystal structure and amorphous structure.

9. A Cr / FeMoAlSiY composite material prepared by the preparation method of a Cr / FeMoAlSiY composite material according to claim 7, characterized in that, The hardness of the Cr / FeMoAlSiY composite material is 5.53 GPa - 10.56 GPa.

10. A nuclear fuel cladding, characterized in that, The surface of this nuclear fuel cladding is provided with the Cr / FeMoAlSiY composite material described in any one of Claims 7 - 9.

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