Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface and preparation method of Cr / TaWMoCrZr nano-multilayer coating

Abstract

The invention discloses a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface and a preparation method, and belongs to the field of material surface modification, the nano multilayer coating comprises Cr layers and TaWMoCrZr refractory high-entropy alloy layers which are alternately laminated; the crystal phase structures of the Cr layer and the TaWMoCrZr refractory high-entropy alloy layer are BCC, and the interface between the Cr layer and the TaWMoCrZr refractory high-entropy alloy layer is a heterogeneous coherent interface; the Cr / TaWMoCrZr nano-multilayer coating is prepared on a substrate by adopting a magnetron sputtering deposition method, due to the template effect of Cr, original amorphous TaWMoCrZr forms a BCC crystal structure through epitaxial growth, the BCC crystal structure has the same preferred orientation as Cr, the microstructure is greatly regulated and controlled, a heterogeneous coherent interface is formed, and the prepared coating is uniform in thickness, uniform in thickness and good in mechanical property. The Cr / TaWMoCrZr nano multilayer coating with the heterogeneous coherent interface has a uniform microstructure, good corrosion and oxidation resistance and irradiation resistance and excellent high-temperature structure stability and mechanical property.

Description

Technical Field

[0001] The invention relates to the field of material surface modification, in particular to a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface and a preparation method thereof. Background Art

[0002] Pure Cr coating has great application potential in aerospace, nuclear fuel storage, military, medical equipment and other fields due to its good corrosion resistance, high melting point, excellent mechanical strength and wear resistance. However, due to the large number of grain boundaries in metals at the nanometer scale, which hinder the movement of dislocations, the plasticity of pure Cr coating is poor, which greatly limits its development and application.

[0003] High entropy alloys have broad application prospects due to their unique organizational structure and excellent comprehensive performance, and have become a research hotspot in recent years. High entropy alloy coatings derived from high entropy alloys also have properties that are superior to traditional alloy coatings, such as mechanical properties, corrosion resistance, wear resistance, oxidation resistance, and radiation resistance. In order to better meet the service requirements of high-temperature environments, high entropy alloy coating elements should be selected from refractory metals to give the material excellent thermodynamic properties. High entropy alloy coatings can be combined with traditional coatings to achieve complementary advantages and common development.

[0004] Heterostructures can optimize the mechanical properties of materials under the synergistic effect of various strengthening mechanisms such as heterogeneous deformation induced (HDI) strengthening, dislocation regulation in nano-heterostructures, and phase change induced plasticity. While improving plasticity, the strength is improved, and the strength-plasticity trade-off is better achieved. Heterogeneous multilayer film structures can greatly improve the mechanical properties of materials. The heterogeneous coherent interface in the multilayer film structure can provide a channel for the movement of dislocations while improving strength, thereby improving plasticity and meeting application requirements.

[0005] Magnetron sputtering is a relatively mature coating preparation technology due to its low energy, controllable deposition rate and good process repeatability. It can be used to prepare nano-multilayer coatings with heterogeneous structures. Due to the high content of high entropy alloy elements, the composition is relatively complex and the controllability is low. Therefore, it has become a current technical difficulty to prepare a metal / high entropy alloy nano-multilayer coating with a heterogeneous coherent interface. Overcoming this difficulty depends on the selection and design of the high entropy alloy composition so that it can have a good lattice matching with the single metal layer to form a heterogeneous coherent interface. The interface density will greatly affect the mechanical properties of the heterogeneous coherent interface nano-multilayer coating. The interface density can be controlled by changing the magnetron sputtering process parameters to improve the material performance. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a Cr / TaWMoCrZr nano-multilayer coating with a heterogeneous coherent interface and a preparation method thereof. By controlling the microstructure of the Cr / TaWMoCrZr nano-multilayer coating by controlling the magnetron sputtering process, the Cr / TaWMoCrZr nano-multilayer coating has a uniform microstructure, good corrosion and oxidation resistance, radiation resistance, and excellent high-temperature structural stability and mechanical properties.

[0007] The present invention is achieved through the following technical solutions: A Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface, comprising Cr layers and TaWMoCrZr refractory high entropy alloy layers alternately stacked; The crystal phase structures of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer are both BCC, and the interface between the Cr layer and the TaWMoCrZr refractory high entropy alloy layer is a heterogeneous coherent interface.

[0008] Preferably, in the same modulation period, the modulation ratio of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer is 1:1, and the thickness is 10 to 100 nm.

[0009] Preferably, the thickness of the Cr / TaWMoCrZr nano multilayer coating is 1.6-5 μm.

[0010] Preferably, in the TaWMoCrZr refractory high entropy alloy layer, the atomic percentage ratio of the five elements Ta, W, Mo, Cr and Zr is 1:1:1:1:1.

[0011] Preferably, the nanoindentation hardness of the Cr / TaWMoCrZr nano multilayer coating is 8 to 11 GPa, and the Young's modulus is 164 to 187 GPa.

[0012] A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface, characterized in that it comprises the following steps: Step 1, cleaning and drying the substrate and then performing vacuum etching; Step 2, preparing a Cr / TaWMoCrZr nano multilayer coating on the substrate by magnetron sputtering; Firstly, a TaWMoCrZr refractory high entropy alloy layer is deposited on the substrate by magnetron co-sputtering using a TaWMoCr alloy target and a Zr target; Then, a Cr layer is deposited on the TaWMoCrZr refractory high entropy alloy layer using a Cr target.

[0013] Secondly, repeating the above process, alternately depositing TaWMoCrZr refractory high entropy alloy layers and Cr layers until the thickness of the nano multilayer coating reaches a predetermined thickness; The deposition time of the TaWMoCrZr refractory high entropy alloy layer is 64-625 s, the deposition time of the Cr layer is 72-714 s, and the modulation period of the magnetron sputtering is 20-200 nm; Step 3: Cool the nano multilayer coating to room temperature to obtain a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface.

[0014] Preferably, in step 2, the DC power of the TaWMoCr alloy target is 100W, the RF power of the Zr target is 100W, and the DC power of the Cr target is 200W.

[0015] Preferably, during the magnetron sputtering process in step 2, the deposition gas pressure is 0.3 Pa and the substrate rotation speed is 15 r / min.

[0016] Preferably, the cooling time in step 3 is 2-3 hours.

[0017] The invention discloses an application of a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface, wherein the nano multilayer coating is applied in the protection of a lead-bismuth fast reactor cladding of a nuclear reactor.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: The present application provides a Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interfaces, in which Cr layers and TaWMoCrZr layers are alternately superimposed to form a large number of heterogeneous coherent interfaces. The heterogeneous coherent interfaces serve as obstacles to dislocation movement, effectively hindering the slip and climb of dislocations, thereby improving the hardness of the coating; secondly, Zr elements with a large difference in atomic radius are introduced into the TaWMoCr matrix. With the increase of the Zr element, TaWMoCr undergoes a large lattice distortion, while still maintaining a BCC structure. TaWMoCrZr is a refractory high-entropy alloy, and this high-entropy design leads to severe lattice distortion, which increases the resistance to dislocation movement, thereby improving the hardness and strength of the material. At the same time, the introduction of the Zr element further increases the lattice distortion, but since the BCC structure is still maintained, this distortion maintains the stability of the structure while strengthening the material; in addition, the Cr layer serves as a template layer to induce amorphous TaWMoCrZr to form a BCC crystal structure through epitaxial growth, and has the same preferential orientation as the Cr layer. The formation of this heterogeneous coherent interface greatly regulates the microstructure and improves the overall performance of the coating.

[0019] The preparation method of the present application regulates the microstructure of the Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface by controlling the modulation period. The change of the modulation period affects the interface density and the performance change of the coating. It is of great significance to prepare a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface and excellent performance by controlling the modulation period to regulate the microstructure of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is an XRD result diagram of the Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface of the present invention; Figure 2 The TEM low-magnification morphology image, selected area electron diffraction and high-resolution image of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface of the present invention; Figure 3 This is an indentation hardness diagram of the Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface of the present invention; Figure 4 The STEM photo and EDS element distribution diagram of the Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface prepared by magnetron sputtering of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0024] A Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface, comprising Cr layers and TaWMoCrZr refractory high entropy alloy layers alternately stacked; The crystal phase structures of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer are both BCC, and a heterogeneous coherent interface is formed between the interfaces through epitaxial growth.

[0025] In the TaWMoCrZr refractory high entropy alloy layer, the atomic percentage ratio of the five elements Ta, W, Mo, Cr and Zr is 1:1:1:1:1.

[0026] The modulation ratio of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer in the same modulation period is 1:1, that is, the thickness of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer is the same, which is 10 to 100 nm.

[0027] The thickness of the Cr / TaWMoCrZr nano multilayer coating is 1.6-5 μm.

[0028] The nano indentation hardness of the Cr / TaWMoCrZr nano multilayer coating is 8 to 11 GPa, and the Young's modulus is 164 to 187 GPa.

[0029] In the Cr / TaWMoCrZr nano-multilayer coating, Cr layers and TaWMoCrZr layers are alternately stacked to form a large number of heterogeneous coherent interfaces. These interfaces act as obstacles to dislocation movement, effectively hindering the slip and climb of dislocations, thereby improving the hardness of the coating; secondly, TaWMoCrZr is a refractory high-entropy alloy, and the atomic percentage ratio of its five elements is 1:1:1:1:1. This high-entropy design leads to severe lattice distortion, which increases the resistance to dislocation movement, thereby improving the hardness and strength of the material. At the same time, the introduction of Zr elements further increases the lattice distortion, but since the BCC structure is still maintained, this distortion maintains the stability of the structure while strengthening the material; in addition, the Cr layer acts as a template layer to induce amorphous TaWMoCrZr to form a BCC crystal structure through epitaxial growth, and has the same preferred orientation as the Cr layer. The formation of this heterogeneous coherent interface greatly regulates the microstructure and improves the overall performance of the coating; the nanoindentation hardness of the Cr / TaWMoCrZr nano-multilayer coating is as high as 8-11GPa, and the Young's modulus is 164-187GPa, showing extremely high hardness and elastic modulus.

[0030] The present application achieves high hardness and high strength of the Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface through solid solution strengthening of high entropy alloy, interface strengthening of nano-multilayer structure, template effect and epitaxial growth, and modulation cycle regulation. At the same time, the coating also has good corrosion resistance, wear resistance and oxidation resistance, as well as adjustable microstructure. The Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface has broad application prospects in aerospace, automobile, energy, electronics and other fields due to its excellent comprehensive performance.

[0031] Correspondingly, the present application also provides a method for preparing a Cr / TaWMoCrZr nano multilayer coating having a heterogeneous coherent interface, comprising the following steps: Step 1: Clean and dry the substrate.

[0032] First, the substrate was polished, and the polished substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes respectively and then dried to remove impurities on the surface of the substrate.

[0033] Step 2: vacuum etching the dried substrate.

[0034] The substrate is a steel substrate or a single crystal silicon substrate. The substrate is etched in a vacuum state, and the back vacuum is drawn to 4.0×10 -4 Pa, the etching power is 200W, the etching pressure is 1.0Pa, and the etching time is 5min.

[0035] Step 3: alternately depositing Cr layers and TaWMoCrZr refractory high entropy alloy layers on the etched substrate by magnetron sputtering to obtain a surface Cr / TaWMoCrZr nano multilayer coating; Firstly, a TaWMoCrZr refractory high entropy alloy layer is deposited on the substrate by magnetron co-sputtering using a TaWMoCr alloy target and a Zr target; The DC power of the TaWMoCr alloy target is 100W, the RF power of the Zr target is 100W, the thickness of the TaWMoCrZr refractory high entropy alloy layer is 10-100nm, and the deposition time of the TaWMoCrZr refractory high entropy alloy layer is: 64-625s.

[0036] Then, a Cr layer is deposited on the TaWMoCrZr refractory high entropy alloy layer using a Cr target.

[0037] The DC power of the Cr target is 200W, the deposition time of the Cr layer is 72~714s, and the thickness of the Cr layer is 10~100nm.

[0038] Secondly, the above process is repeated to alternately deposit TaWMoCrZr refractory high entropy alloy layers and Cr layers until the thickness of the nano multilayer coating reaches a predetermined thickness.

[0039] In the process of alternately depositing TaWMoCrZr refractory high entropy alloy layer and Cr layer by magnetron sputtering, the deposition gas pressure is 0.3Pa, the substrate rotation speed is 15r / min, the modulation period is 20~200nm, and the thickness of the nano multilayer coating is 1.6~5μm.

[0040] Step 4: Cool the Cr / TaWMoCrZr nano multilayer coating to room temperature in the furnace to obtain a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface.

[0041] After deposition, the substrate is fully cooled to room temperature in the high vacuum coating chamber before being taken out to prevent debonding and cracking caused by the difference in thermal expansion coefficients between the substrate and the coating material, and to prevent oxidation with air due to high temperature.

[0042] Example 1 A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S1, the polished single crystal silicon substrate is ultrasonically cleaned in acetone and anhydrous ethanol for 15 min respectively and then dried to remove impurities on the substrate surface.

[0043] S2, vacuum etching is performed on the cleaned and dried substrate, the etching power is 200 W, the etching pressure is 1.0 Pa, the etching time is 5 min, and the back vacuum degree is evacuated to below 4.0×10-4 Pa.

[0044] S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0045] Firstly, a TaWMoCrZr layer was co-sputtered by using a TaWMoCr alloy target and a Zr target, the DC power of the TaWMoCr alloy target was 100W, and the RF power of the Zr target was 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0046] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0047] During the magnetron sputtering process, the deposition pressure was 0.3Pa, the substrate speed was 15r / min, the deposition time of the Cr layer was 72s, and the deposition time of the TaWMoCrZr layer was 64s. The single layer thickness of the Cr layer and the TaWMoCrZr layer was 10nm, the modulation period was 20nm, the number of cycles was 100, and the total thickness of the nano-multilayer coating was 2μm.

[0048] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 2 μm. The microstructure characterization and performance test of the prepared Cr / TaWMoCrZr nano multilayer coating are performed, see Figure 1-4 .

[0049] Example 2 A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S1, the polished single crystal silicon substrate is ultrasonically cleaned in acetone and anhydrous ethanol for 15 min respectively and then dried to remove impurities on the substrate surface.

[0050] S2, vacuum etching is performed on the cleaned and dried substrate, the etching power is 200 W, the etching pressure is 1.0 Pa, the etching time is 5 min, and the back vacuum degree is evacuated to below 4.0×10-4 Pa.

[0051] S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0052] Firstly, a TaWMoCrZr layer was co-sputtered by using a TaWMoCr alloy target and a Zr target, the DC power of the TaWMoCr alloy target was 100W, and the RF power of the Zr target was 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0053] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0054] During the magnetron sputtering process, the deposition gas pressure was 0.3Pa, the substrate rotation speed was 15r / min, the deposition time of the Cr layer was 179s, the deposition time of the TaWMoCrZr layer was 156s, the single layer thickness of the Cr layer and the TaWMoCrZr layer were both 25nm, the modulation period was 50nm, the number of cycles was 40, and the total thickness of the nano-multilayer coating was 2μm.

[0055] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 2 μm. The microstructure characterization and performance test of the prepared Cr / TaWMoCrZr nano multilayer coating are performed, see Figure 1-4 .

[0056] Example 3 A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S1, the polished single crystal silicon substrate is ultrasonically cleaned in acetone and anhydrous ethanol for 15 min respectively and then dried to remove impurities on the substrate surface.

[0057] S2, vacuum etching is performed on the cleaned and dried substrate, the etching power is 200 W, the etching pressure is 1.0 Pa, the etching time is 5 min, and the back vacuum degree is evacuated to below 4.0×10-4 Pa.

[0058] S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0059] Firstly, a TaWMoCrZr layer was co-sputtered by using a TaWMoCr alloy target and a Zr target, the DC power of the TaWMoCr alloy target was 100W, and the RF power of the Zr target was 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0060] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0061] During the magnetron sputtering process, the deposition gas pressure was 0.3Pa, the substrate rotation speed was 15r / min, the deposition time of the Cr layer was 357s, the deposition time of the TaWMoCrZr layer was 312s, the single layer thickness of the Cr layer and the TaWMoCrZr layer were both 50nm, the modulation period was 100nm, the number of cycles was 20, and the total thickness of the nano-multilayer coating was 2μm.

[0062] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 2 μm. The microstructure characterization and performance test of the prepared Cr / TaWMoCrZr nano multilayer coating are performed, see Figure 1-4 .

[0063] Example 4 A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S1, the polished single crystal silicon substrate is ultrasonically cleaned in acetone and anhydrous ethanol for 15 min respectively and then dried to remove impurities on the substrate surface.

[0064] S2, vacuum etching is performed on the cleaned and dried substrate, the etching power is 200 W, the etching pressure is 1.0 Pa, the etching time is 5 min, and the back vacuum degree is evacuated to below 4.0×10-4 Pa.

[0065] S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0066] Firstly, a TaWMoCr alloy target and a Zr target are co-sputtered to deposit a TaWMoCrZr layer, the DC power of the TaWMoCr alloy target is 100W, and the RF power of the Zr target is 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0067] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0068] During the magnetron sputtering process, the deposition gas pressure was 0.3Pa, the substrate rotation speed was 15r / min, the deposition time of the Cr layer was 714s, the deposition time of the TaWMoCrZr layer was 625s, the single layer thickness of the Cr layer and the TaWMoCrZr layer were both 100nm, the modulation period was 200nm, the number of cycles was 10, and the total thickness of the nano-multilayer coating was 2μm.

[0069] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 2 μm. The microstructure characterization and performance test of the prepared Cr / TaWMoCrZr nano multilayer coating are performed, see Figure 1-4 .

[0070] Example 5 The difference between this embodiment and embodiments 1-4 is that the thickness of the prepared nano multilayer coating is 1.6 μm, and the difference in the preparation method is step 3. The remaining steps are the same and will not be repeated.

[0071] A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0072] Firstly, a TaWMoCr alloy target and a Zr target are co-sputtered to deposit a TaWMoCrZr layer, the DC power of the TaWMoCr alloy target is 100W, and the RF power of the Zr target is 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0073] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0074] During the magnetron sputtering process, the deposition gas pressure was 0.3Pa, the substrate rotation speed was 15r / min, the deposition time of the Cr layer was 714s, the deposition time of the TaWMoCrZr layer was 625s, the single layer thickness of the Cr layer and the TaWMoCrZr layer were both 100nm, the modulation period was 200nm, the number of cycles was 8, and the total thickness of the nano-multilayer coating was 1.6μm.

[0075] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 1.6 μm.

[0076] Example 6 The difference between this embodiment and embodiments 1-4 is that the thickness of the prepared nano multilayer coating is 5 μm, and the difference in the preparation method is step 3. The remaining steps are the same and will not be repeated.

[0077] A method for preparing a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface comprises the following steps: S3, Cr / TaWMoCrZr nano-multilayer coating with heterogeneous coherent interface was prepared on the substrate by magnetron sputtering.

[0078] Firstly, a TaWMoCr alloy target and a Zr target are co-sputtered to deposit a TaWMoCrZr layer, the DC power of the TaWMoCr alloy target is 100W, and the RF power of the Zr target is 100W; Then, a Cr alloy target is used to deposit a Cr layer, and the DC power of the Cr target is 200W.

[0079] Next, the above process was repeated to alternately sputter-deposit TaWMoCrZr layers and Cr layers.

[0080] During the magnetron sputtering process, the deposition gas pressure was 0.3Pa, the substrate rotation speed was 15r / min, the deposition time of the Cr layer was 714s, the deposition time of the TaWMoCrZr layer was 625s, the single layer thickness of the Cr layer and the TaWMoCrZr layer were both 100nm, the modulation period was 200nm, the number of cycles was 25, and the total thickness of the nano-multilayer coating was 5μm.

[0081] S4, after the sample is naturally cooled in the vacuum coating chamber for 2-3 hours to room temperature, it is taken out to obtain a Cr / TaWMoCrZr nano multilayer coating with a thickness of about 5 μm.

[0082] See also Figure 1-4 , are the microstructure characterization and performance test results of the Cr / TaWMoCrZr nano-multilayer coatings prepared in Examples 1-4 of the present application.

[0083] Figure 1 The XRD result diagram of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface of the present invention is an obvious crystal peak. The prepared Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface has the same preferred orientation.

[0084] Figure 2 The TEM low-power morphology image, selected area electron diffraction and high-resolution image of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface of the present invention. Combined, the selected area electron diffraction has two sets of symmetrical diffraction spots, and the interface of the high-resolution image is a coherent interface with obvious epitaxial growth characteristics.

[0085] Figure 3 The indentation hardness of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface of the present invention shows a certain size dependence, and the hardness gradually decreases with the increase of layer thickness. This is because as the layer thickness increases, the interface density decreases, the elastic strain field near the interface decreases, and the barrier effect on dislocations weakens, resulting in a decrease in hardness. At the nanoscale with a single layer thickness greater than 5nm, there is a similar size effect.

[0086] Figure 4 The STEM photo and EDS element distribution diagram of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface prepared by magnetron sputtering of the present invention. Each element is evenly distributed in the structure, the interface is clear and straight, and it has excellent mechanical properties and stability.

[0087] The present application prepares Cr / TaWMoCrZr nano-multilayer coatings by depositing on a clean silicon substrate by magnetron sputtering deposition. Taking advantage of the magnetron sputtering technology, a Cr / TaWMoCrZr nano-multilayer coating with uniform distribution of alloy elements, different microstructures and excellent performance is prepared. Due to the template effect of Cr, the original amorphous TaWMoCrZr forms a BCC crystal structure through epitaxial growth, which has the same preferred orientation as Cr, greatly regulates the microstructure, and forms a heterogeneous coherent interface. In addition, the microstructure of the Cr / TaWMoCrZr nano-multilayer coating of the heterogeneous coherent interface is regulated by controlling the modulation period. The change of the modulation period affects the interface density and the performance change of the coating. This is because the difference in lattice constants between heterogeneous materials (although coherent, there is still a small mismatch) will introduce an elastic strain field near the interface. This strain field interacts with the stress field of the dislocation, hindering the dislocation slip and increasing the strength. The generated elastic strain field allows dislocations to be temporarily stored near the interface, forming a dislocation network. These stored dislocations interact with newly generated dislocations during deformation to enhance the uniform deformation capability of the material. It can be seen that the interface density greatly affects the mechanical properties of heterogeneous coherent interface nano-multilayer coatings. It is of great significance to prepare Cr / TaWMoCrZr nano-multilayer coatings with excellent performance and heterogeneous coherent interfaces by controlling the modulation period to regulate the microstructure of the coating.

[0088] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A Cr / TaWMoCrZr nano-multilayer coating with a heterogeneous coherent interface, characterized in that: It includes Cr layers and TaWMoCrZr refractory high entropy alloy layers that are alternately stacked; The crystal phase structures of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer are both BCC, and the interface between the Cr layer and the TaWMoCrZr refractory high entropy alloy layer is a heterogeneous coherent interface.

2. The Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface according to claim 1, characterized in that: The modulation ratio of the Cr layer and the TaWMoCrZr refractory high entropy alloy layer in the same modulation period is 1:1, and the thickness is 10 to 100 nm.

3. The Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface according to claim 1, characterized in that: The thickness of the Cr / TaWMoCrZr nano multilayer coating is 1.6-5 μm.

4. The Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface according to claim 1, characterized in that: In the TaWMoCrZr refractory high entropy alloy layer, the atomic percentage ratio of the five elements Ta, W, Mo, Cr and Zr is 1:1:1:1:

1.

5. The Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface according to claim 1, characterized in that: The nano indentation hardness of the Cr / TaWMoCrZr nano multilayer coating is 8 to 11 GPa, and the Young's modulus is 164 to 187 GPa.

6. A method for preparing a Cr / TaWMoCrZr nano multilayer coating having a heterogeneous coherent interface according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, cleaning and drying the substrate and then performing vacuum etching; Step 2, preparing a Cr / TaWMoCrZr nano multilayer coating on the substrate by magnetron sputtering; Firstly, a TaWMoCrZr refractory high entropy alloy layer is deposited on the substrate by magnetron co-sputtering using a TaWMoCr alloy target and a Zr target; Then, a Cr layer is deposited on the TaWMoCrZr refractory high entropy alloy layer using a Cr target. Secondly, repeating the above process, alternately depositing TaWMoCrZr refractory high entropy alloy layers and Cr layers until the thickness of the nano multilayer coating reaches a predetermined thickness; The deposition time of the TaWMoCrZr refractory high entropy alloy layer is 64-625 s, the deposition time of the Cr layer is 72-714 s, and the modulation period of the magnetron sputtering is 20-200 nm; Step 3: Cool the nano multilayer coating to room temperature to obtain a Cr / TaWMoCrZr nano multilayer coating with a heterogeneous coherent interface.

7. The method for preparing a Cr / TaWMoCrZr nano multilayer coating having a heterogeneous coherent interface according to claim 6, characterized in that: In step 2, the DC power of the TaWMoCr alloy target is 100W, the RF power of the Zr target is 100W, and the DC power of the Cr target is 200W.

8. The method for preparing a Cr / TaWMoCrZr nano multilayer coating having a heterogeneous coherent interface according to claim 6, characterized in that: During the magnetron sputtering process described in step 2, the deposition gas pressure is 0.3 Pa and the substrate rotation speed is 15 r / min.

9. The method for preparing a Cr / TaWMoCrZr nano multilayer coating having a heterogeneous coherent interface according to claim 6, characterized in that: The cooling time in step 3 is 2-3 hours.

10. An application of the Cr / TaWMoCrZr nano multilayer coating with heterogeneous coherent interface according to any one of claims 1 to 5, characterized in that: The nano multilayer coating is applied in the protection of the lead-bismuth fast reactor cladding of a nuclear reactor.

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