Fatigue fracture resistant high-entropy alloy fastener and preparation method thereof

Abstract

The invention discloses an anti-fatigue-fracture high-entropy alloy fastener and a preparation method thereof, and belongs to the technical field of fastening materials, the anti-fatigue-fracture high-entropy alloy fastener comprises a fastener base body, a stress sensor is arranged on the end face of one end of the fastener base body, and the fastener base body is Ni-Co-Fe-Mo-Al high-entropy alloy; the stress sensor comprises a bonding layer, a supporting layer, a piezoelectric functional layer and a wear-resistant electrode layer which are stacked from inside to outside, the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy alloy layer, the supporting layer is a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano multilayer ceramic layer, the piezoelectric functional layer is a ZnO-doped layer, and the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy conductive ceramic coating. According to the method, the Ni-Co-Fe-Mo-Al high-entropy alloy material is used for preparing the high-strength anti-fatigue-fracture fastener, the problems that traditional materials such as Ti, Cr and Ag are low in hardness and poor in friction resistance can be solved, the hardness of the electrode is greatly improved, and therefore the abrasion resistance of the electrode is greatly improved, and a new fastener development thought is provided for the industry.

Description

Technical Field

[0001] The present invention relates to the technical field of fastening materials, and in particular, to a high-entropy alloy fastener with anti-fatigue fracture and a preparation method thereof. Background Art

[0002] In the manufacture of fasteners, the correct selection of fastener materials is a very important link, because the performance of fasteners is closely related to their materials; if the material selection is improper or incorrect, it may result in unmet performance requirements, shortened service life, or even accidents, processing difficulties, high manufacturing costs, etc. Therefore, the selection of fastener materials is a very important link.

[0003] Today, advanced manufacturing represented by large aircraft, large power generation equipment, automobiles, high-speed trains, large ships, large complete sets of equipment, etc. has become an important development direction, and fasteners have also entered an important development stage. Bolts with a performance grade above 8.8 are called high-strength bolts. High-strength bolts can withstand greater loads than ordinary bolts of the same specification and are mostly used for the connection of bridges, rails, high-pressure and ultra-high-pressure equipment. The fracture of such bolts is mostly brittle fracture. For high-strength bolts applied to ultra-high-pressure equipment, in order to ensure the sealing of the container, a relatively large prestress needs to be applied.

[0004] The current national standard only lists up to M39. For large-size specifications, especially high-strength bolts with a length greater than 10-15 times, there are no relevant domestic products. High-strength bolts are commonly used for the connection of bridges, rails, high-pressure and ultra-high-pressure equipment, and their materials include alloy steels such as 40Cr and 42CrMo, and carbon steels such as 8.8 grade, 10.9 grade, and 12.9 grade. 40Cr has certain toughness and hardness and relatively low price, and is suitable for applications with general high-strength requirements; 42CrMo has high strength and toughness and is suitable for occasions that bear large loads and impacts; 45# steel has good hardness and wear resistance, but is relatively brittle and is mostly used for manufacturing nuts and stud rods; 35CrMo has good strength and toughness and is suitable for manufacturing high-strength bolts with high requirements and bearing greater pressure; 20CrMoTi titanium alloy strengthening material is light in weight, corrosion-resistant and wear-resistant, and has excellent strength and toughness. If classified according to strength grades, 8.8-grade carbon steel is suitable for general structural connections; 10.9-grade carbon steel has higher strength and is suitable for higher-strength structural connections; 12.9-grade carbon steel has very high strength and is suitable for applications with very strict strength requirements. Generally speaking, if the application environment is complex, materials with corrosion resistance and wear resistance should be selected; if greater pressure needs to be borne, materials with high strength should be selected; if it is a working condition that bears tensile force, then materials with high strength and good toughness need to be selected. However, there is less research on fasteners with a tensile strength above 1500 MPa at present, and no relevant research reports have been seen. In particular, there is even less research on high-strength fasteners with anti-fatigue fracture in fields such as wind power generation.

[0005] High-entropy alloys (HEAs) are a new type of material with excellent properties and have attracted wide attention in the scientific community for their excellent mechanical properties, corrosion resistance, and thermal stability. High-entropy alloys are crystals in which more than five elements randomly occupy lattice sites. Ye Junwei et al. discovered alloys with a face-centered cubic solid-solution structure represented by CoCrCuFeNi; Zhang Yong et al. discovered alloys with a body-centered cubic solid-solution structure represented by A1CoCrFeNi. Nowadays, the high-entropy concept has been widely applied to various materials such as oxides, chalcogenides, and halides. The fracture of materials is often related to safety issues. Generally speaking, it can be divided into brittle and ductile fractures according to the failure strain. Brittle fractures show no signs of plastic deformation and usually occur in a catastrophic manner. Developing new metallic materials with excellent tensile and fatigue properties is of great significance. It is reported that when the temperature drops from 298 K to 77 K, the fracture toughness of the CrMnFeCoNi high-entropy alloy remains almost constant, while the fracture toughness of the CrCoNi high-entropy alloy slightly increases. Among these HEAs, there is no sharp ductile-brittle transition like many traditional alloys such as steel, amorphous alloys, magnesium alloys, porous metals, and nanometals, indicating that these alloys may be excellent candidates for applications under extremely cold conditions, such as materials for ship hulls, aircraft, and cryogenic storage tanks.

[0006] High-entropy alloys have the characteristics of high hardness and high strength and can be widely used in many fields such as motors, transformers, machine tools, consumer electronics, engine blades, jet engine engines, and nuclear fusion. High-entropy alloys are a brand-new alloy field that breaks out of the design framework of traditional alloys. They are special alloy systems with many excellent properties. Adjusting their composition can further optimize their properties, so they have extremely broad application prospects. The research on high-entropy alloy fasteners in China has just started. Although many researchers have begun to pay attention to the research of such alloys, the relevant data are still in the laboratory stage and have not really entered the actual application stage.

[0007] In view of this, the inventor of the present invention conducted in-depth research on this demand, and thus this case was created. Summary of the Invention

[0008] The present invention first forms a Ni-Co-Fe-Mo-Al high-entropy material by regulating the proportion of alloying elements, and obtains a high-entropy alloy material with a tensile strength exceeding 1500 MPa by using special strengthening mechanisms such as the high-entropy effect. On this basis, it is formed into a high-strength fastener through upsetting and thread rolling. Then, a ZnO composite ultrasonic sensor is prepared on the head of the bolt to form an intelligent bolt product. Designing the Ni-Co-Fe-Mo-Al high-entropy material and processing it into a high-strength fastener, and machining a stress sensor at its end to realize the detection and monitoring of the stress state during the application process, which has important value for the anti-fatigue and anti-fracture fastening connection requirements in complex environments.

[0009] One of the objectives of the present invention is to provide an anti-fatigue and fracture high-entropy alloy fastener, which includes a fastener matrix, and a stress sensor is arranged on one end face of the fastener matrix. The fastener matrix is a Ni-Co-Fe-Mo-Al high-entropy alloy; for the first time, the Ni-Co-Fe-Mo-Al high-entropy alloy material is prepared into a high-strength anti-fatigue and fracture fastener, which not only solves the problem that there is no ultra-high-strength anti-fatigue fastener at home and abroad at present, but also provides a new idea for the development of fasteners in the industry.

[0010] The stress sensor includes a bonding layer, a support layer, a piezoelectric functional layer, and a wear-resistant electrode layer stacked from the inside to the outside. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy alloy layer, the support layer is a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer ceramic layer, the piezoelectric functional layer is a doped ZnO layer, and the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy conductive ceramic coating.

[0011] Preferably, the structure of the fastener matrix is a face-centered cubic structure, and its components are Ni: 5-25 at.%, Co: 5-20 at.%, Fe: 20-40 at.%, Mo: 5-15 at.%, Al: 2-20 at.%; its crystal structure is polycrystalline, and the grain size is 5-30 microns.

[0012] Preferably, the piezoelectric functional layer is a ternary alloy co-doped piezoelectric material of V, Fe, and Cr, where the content of V is 0-5 at.%, the content of Fe is 1-5 at.%, and the content of Cr is 1-10 at.%. Co-doping ZnO with a ternary alloy of V, Fe, and Cr forms a novel ZnVFeCrO piezoelectric material, which improves the piezoelectric constant of the material and promotes the expansion of its application fields.

[0013] Preferably, the coating crystallization orientation of the piezoelectric functional layer is the (002) crystallization orientation, the crystal structure is columnar crystal, and the diameter of the columnar crystal is 0.5-2.0 microns.

[0014] Preferably, the modulation period of the support layer is 15 - 30 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 10 - 20 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 5 - 10 nm.

[0015] Preferably, the contact resistance of the wear-resistant electrode layer is less than 100 ohms, and the coating thickness is 1 - 20 μm.

[0016] Preferably, the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline alloy coating with a preferred (110) crystal plane orientation, the nanocrystalline grain size is 10 - 20 nm, and the coating thickness is 20 - 100 nm.

[0017] Preferably, a groove is formed in the head of the fastener base body, and the stress sensor is disposed in the groove.

[0018] The second object of the present invention is to provide a method for preparing the above anti-fatigue fracture high-entropy alloy fastener. By combining high-power arc ion plating and radio frequency sputtering technologies in the preparation of an ultrasonic thin film sensor, not only can the adhesion problem be solved, but also the deposition rate problem can be solved, realizing the possibility of preparing an ultrasonic sensor on various substrate materials. The heat treatment of the fastener base body is realized by solution treatment and aging. The solution treatment temperature is 800 - 1000 °C, and the holding time is 2 - 10 hours; the aging temperature is 400 - 600 °C, and the holding time is 4 - 10 hours.

[0019] Preferably, the method for preparing the above anti-fatigue fracture high-entropy alloy fastener includes the following steps:

[0020] Step 1: Melting a Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 8 - 100 mm, and performing solution treatment and aging treatment;

[0021] Step 2: The rod after solution treatment and aging is made into a fastener base body by hot forging and hot rolling. The forging temperature is 800 - 900 °C, and the rolling temperature is 300 - 500 °C; and the head of the fastener base body is polished;

[0022] Step 3: Depositing a bonding layer in an argon environment by arc ion plating technology under the conditions of 1 - 2 Pa and 50 - 150 V;

[0023] Depositing a support layer in an argon + nitrogen environment by arc ion plating under the conditions of 1 - 3 Pa and 50 - 150 V, and forming a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer film by intermittently introducing nitrogen;

[0024] Deposit the piezoelectric functional layer under the conditions of 0.5 - 2 Pa and 10 - 100 V; deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 1 - 3 Pa and 0 - 200 V to obtain the anti-fatigue fracture high-entropy alloy fastener.

[0025] Beneficial effects:

[0026] There are currently no relevant reports on the high-entropy alloy high-strength anti-fatigue fasteners prepared by the present invention, providing new ideas for the research and development of new high-strength fasteners. In addition, the present invention applies an ultrasonic stress sensor to the surface of the high-strength anti-fatigue fastener, which can detect and monitor the stress state in the fastener in real time. The technical solution of the present invention has at least the following beneficial effects:

[0027] (1) For the first time, Ni-Co-Fe-Mo-Al high-entropy alloy materials are used to prepare high-strength anti-fatigue fracture fasteners, which can not only solve the problems of low hardness and poor friction resistance of traditional materials such as Ti, Cr, and Ag, but also greatly improve the hardness of the electrode, thereby greatly improving its wear resistance, changing the problem that there are no ultra-high-strength anti-fatigue fasteners at home and abroad, and providing new ideas for the development of fasteners in the industry.

[0028] (2) Co-doping ZnO with V, Fe, and Cr ternary alloys to form a new ZnVFeCrO piezoelectric material, which can improve the piezoelectric constant of the material and promote the expansion of its application fields; and preparing a ZnO pressure sensor on the high-strength anti-fatigue fastener can realize the detection and monitoring of the stress magnitude change during the use of the fastener, which has important value for the safe operation of high-end equipment.

[0029] (3) Use arc ion plating technology to prepare Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayers, which not only improve the hardness of the coating, but also, as a metal-ceramic composite material, have low stress.

[0030] (4) Combining high-power arc ion plating and radio frequency sputtering technologies in the preparation of ultrasonic thin film sensors can not only solve the adhesion problem, but also solve the deposition rate problem, making it possible to prepare ultrasonic sensors on a variety of substrate materials. Description of the drawings

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1It is a schematic structural diagram of the high-entropy alloy fastener with anti-fatigue fracture in the present invention;

[0033] Figure 2 It is a schematic diagram of the piezoelectric thin film coating device in the present invention;

[0034] Figure 3 It is a schematic structural diagram of the stress sensor layer in the present invention;

[0035] Figure 4 It is a schematic diagram of the high-entropy alloy fastener in the present invention. Specific embodiments

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In this embodiment, the Ni-Co-Fe-Mo-Al high-entropy alloy material is first used to prepare high-strength anti-fatigue fracture fasteners, which can not only solve the problems of low hardness and poor friction resistance of traditional materials such as Ti, Cr, and Ag, but also greatly improve the hardness of the electrode, thereby greatly improving its wear resistance, changing the problem that there is no ultra-high-strength anti-fatigue fastener at home and abroad, and providing a new idea for the development of fasteners in the industry. The specific embodiments are as follows:

[0038] An anti-fatigue fracture high-entropy alloy fastener includes a fastener matrix, and a stress sensor is arranged on one end face of the fastener matrix. The fastener matrix is a Ni-Co-Fe-Mo-Al high-entropy alloy; for the first time, the Ni-Co-Fe-Mo-Al high-entropy alloy material is used to prepare high-strength anti-fatigue fracture fasteners, which not only changes the problem that there is no ultra-high-strength anti-fatigue fastener at home and abroad, but also provides a new idea for the development of fasteners in the industry.

[0039] The stress sensor includes a bonding layer, a support layer, a piezoelectric functional layer, and a wear-resistant electrode layer stacked from the inside to the outside. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy alloy layer, the support layer is a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer ceramic layer, the piezoelectric functional layer is a doped ZnO layer, preferably a ZnVFeCrO layer, and the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy conductive ceramic coating.

[0040] As a preferred embodiment, the structure of the fastener substrate is a face-centered cubic structure, and its composition is Ni: 5-25 at.%, Co: 5-20 at.%, Fe: 20-40 at.%, Mo: 5-15 at.%, Al: 2-20 at.%; its crystal structure is polycrystalline, and the grain size is 5-30 microns.

[0041] As a preferred embodiment, the piezoelectric functional layer is a ternary alloy co-doped piezoelectric material of V, Fe, and Cr, where the V content is 0-5 at.%, the Fe content is 1-5 at.%, and the Cr content is 1-10 at.%. Co-doping ZnO with a ternary alloy of V, Fe, and Cr forms a novel ZnVFeCrO piezoelectric material, which improves the piezoelectric constant of the material and promotes the expansion of its application fields.

[0042] As a preferred embodiment, the coating crystallization orientation of the piezoelectric functional layer is the (002) crystallization orientation, the crystal structure is columnar crystals, and the diameter of the columnar crystals is 0.5-2.0 microns.

[0043] As a preferred embodiment, the modulation period of the support layer is 15-30 nm, the thickness of the single-layer Ni-Co-Fe-Mo-Al layer is 10-20 nm, and the thickness of the single-layer Ni-Co-Fe-Mo-Al-N layer is 5-10 nm.

[0044] As a preferred embodiment, the contact resistance of the wear-resistant electrode layer is less than 100 ohms, and the coating thickness is 1-20 microns.

[0045] As a preferred embodiment, the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline alloy coating with a preferred orientation of the (110) crystal plane, the grain size of the nanocrystals is 10-20 nm, and the coating thickness is 20-100 nm.

[0046] As a preferred embodiment, a groove is formed in the head of the fastener substrate, and the stress sensor is disposed in the groove.

[0047] A preparation method of the above anti-fatigue fracture high-entropy alloy fastener, which combines high-power arc ion plating and radio frequency sputtering technologies in the preparation of ultrasonic thin film sensors, can not only solve the adhesion problem, but also solve the deposition rate problem, and realize the possibility of preparing ultrasonic sensors on various substrate materials. The heat treatment of the fastener substrate is realized by solution treatment and aging treatment. The solution temperature is 800-1000 °C, and the heat preservation time is 2-10 hours; the aging temperature is 400-600 °C, and the heat preservation time is 4-10 hours.

[0048] As a preferred embodiment, the preparation method of the above anti-fatigue fracture high-entropy alloy fastener includes the following steps:

[0049] Step 1: Melting the Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 8-100 mm, and performing solution treatment and aging treatment;

[0050] Step 2: The rod after solution treatment and aging treatment is made into a fastener substrate by hot heading and hot rolling. The heading temperature is 800-900 °C, and the rolling temperature is 300-500 °C; and the head of the fastener substrate is polished;

[0051] Step 3: Depositing a bonding layer in an argon environment by arc ion plating technology under the conditions of 1-2 Pa and 50-150 V;

[0052] Depositing a support layer by arc ion plating in an argon + nitrogen environment under the conditions of 1-3 Pa and 50-150 V, and intermittently introducing nitrogen to form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer film;

[0053] Depositing a piezoelectric functional layer under the conditions of 0.5-2 Pa and 10-100 V; depositing a wear-resistant electrode layer in a nitrogen environment under the conditions of 1-3 Pa and 0-200 V to obtain the anti-fatigue fracture high-entropy alloy fastener.

[0054] As Figure 1 The schematic diagram of the anti-fatigue fracture high-strength high-entropy alloy fastener of the present invention is shown. The stress sensor 103 is on the head 101 of the fastener 100. A groove 102 is processed on the head 101, and the stress sensor 103 is prepared in the groove. The purpose of the groove 102 is to protect the stress sensor 103 from being damaged.

[0055] As Figure 2The device used for preparing fasteners in the present invention is shown. The vacuum chamber of the device is surrounded by a furnace wall. The vacuum chamber is provided with an air extraction port 4, and a vacuum pumping unit evacuates the vacuum chamber through the air extraction port 4. The four corners of the vacuum chamber are heaters 3 with a heating power of 30 kW to improve the heating efficiency. Three targets are installed on the furnace wall in three columns, including an etching Cr target 1, a Ni-Co-Fe-Mo-Al coating arc target 2, and a ZnVFeCrO target 6 respectively. The sample 7 is installed on the workpiece holder 5. This layout significantly increases the plasma density in the vacuum chamber, and the workpiece is completely immersed in the plasma, resulting in a significant increase in the coating deposition rate, hardness, and adhesion. Due to the optimization of the target structure, the magnetic field distribution is more uniform, making the etching of the magnetron sputtering target surface uniform and improving the coating uniformity.

[0056] As Figure 3 It is a schematic diagram of the stress sensor layer structure in the present invention. As can be seen from the figure, there are composition and hardness gradients in the coating structure, reducing the stress of the coating and enabling the deposition of a relatively thick piezoelectric coating. It includes a substrate 10, and a Ni-Co-Fe-Mo-Al high-entropy bonding layer 20, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N high-entropy nano-multilayer support layer 30, a ZnVFeCrO piezoelectric functional layer 40, and a Ni-Co-Fe-Mo-Al-N high-entropy ceramic conductive layer 50 deposited sequentially on the surface of the substrate 10.

[0057] The Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N high-entropy nano-multilayer support layer 30 is composed of alternately stacked Ni-Co-Fe-Mo-Al layers 31 and Ni-Co-Fe-Mo-Al-N layers 32.

[0058] Figure 4 It is a microstructure morphology diagram of the high-entropy alloy material after solution treatment + failure treatment in the present invention.

[0059] The beneficial effects of the anti-fatigue fracture high-entropy alloy fasteners and their preparation process in the present invention are further evaluated through several sets of examples and comparative examples below.

[0060] Example 1:

[0061] The preparation process of the anti-fatigue fracture high-entropy alloy fasteners in this example includes the following steps:

[0062] Step 1: The Ni-Co-Fe-Mo-Al high-entropy alloy material is melted in a furnace to make a rod with a diameter of 8 mm, and then solution treatment and failure treatment are carried out. The solution temperature is 800 °C, and the holding time is 2 hours; the failure temperature is 400 °C, and the holding time is 4 hours.

[0063] Step 2: The bars after solutionizing failure treatment are made into fastener bases through hot heading and hot rolling thread. The heading temperature is 800°C, and the rolling thread temperature is 300°C; and the head of the fastener base is polished.

[0064] Step 3: Deposit a bonding layer in an argon environment using arc ion plating technology under the conditions of 1 Pa and 50 V; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with (110) crystal plane preferred orientation. The nanocrystalline grain size is 10 nm, and the coating thickness is 20 nm.

[0065] Deposit a support layer in an argon + nitrogen environment using arc ion plating under the conditions of 1 Pa and 50 V. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed; the modulation period is 15 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 10 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 5 nm.

[0066] Deposit a piezoelectric functional layer under the conditions of 0.5 Pa and 10 V. It is a V, Fe, Cr ternary alloy co-doped piezoelectric material. The V content is 0 at.%, the Fe content is 1 at.%, and the Cr content is 1 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystal, and the columnar crystal diameter is 0.5 μm.

[0067] Deposit a wear-resistant electrode layer in a nitrogen environment under the conditions of 1 Pa and 0 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 1 μm.

[0068] Finally, the anti-fatigue fracture high-entropy alloy fastener is obtained.

[0069] Example 2:

[0070] In this example, the preparation process of the anti-fatigue fracture high-entropy alloy fastener includes the following steps:

[0071] Step 1: The Ni-Co-Fe-Mo-Al high-entropy alloy material is melted in a furnace to make a bar with a diameter of 100 mm, and solutionizing and failure treatment are carried out. The solutionizing temperature is 1000°C, and the holding time is 10 hours; the failure temperature is 600°C, and the holding time is 10 hours.

[0072] Step 2: The bars after solutionizing failure treatment are made into fastener bases through hot heading and hot rolling thread. The heading temperature is 900°C, and the rolling thread temperature is 500°C; and the head of the fastener base is polished.

[0073] Step 3: Deposit a bonding layer in an argon environment using arc ion plating technology under the conditions of 2 Pa and 150 V; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with a preferred orientation of (110) crystal plane, the nanocrystalline grain size is 20 nm, and the coating thickness is 100 nm;

[0074] Deposit a support layer in an argon + nitrogen environment using arc ion plating under the conditions of 3 Pa and 150 V. Intermittently introduce nitrogen to form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film; the modulation period is 30 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nm;

[0075] Deposit a piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 5 at.%; the Fe content is 5 at.%; the Cr content is 10 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 2 μm;

[0076] Deposit a wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 200 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 μm;

[0077] Finally, obtain the anti-fatigue fracture high-entropy alloy fastener.

[0078] Example 3:

[0079] The preparation process of the anti-fatigue fracture high-entropy alloy fastener in this example includes the following steps:

[0080] Step 1: Melt a Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 40 mm, and perform solution and aging treatments. The solution temperature is 850 °C, and the holding time is 5 hours; the aging temperature is 450 °C, and the holding time is 5 hours;

[0081] Step 2: The rod after solution and aging treatments is made into a fastener substrate through hot upsetting and hot rolling. The upsetting temperature is 850 °C, and the rolling temperature is 350 °C; and polish the head of the fastener substrate;

[0082] Step 3: Deposit a bonding layer in an argon environment using arc ion plating technology under the conditions of 1 Pa and 100 V; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with a preferred orientation of (110) crystal plane, the nanocrystalline grain size is 15 nm, and the coating thickness is 30 nm;

[0083] Deposit a support layer by arc ion plating in an argon + nitrogen environment under the conditions of 2 Pa and 100 V. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed. The modulation period is 20 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 10 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nm.

[0084] Deposit a piezoelectric functional layer under the conditions of 1 Pa and 100 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 1 at.%, the Fe content is 2 at.%, and the Cr content is 1 at.%. The coating crystallization orientation is the (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 1.2 μm.

[0085] Deposit a wear-resistant electrode layer in a nitrogen environment under the conditions of 2 Pa and 100 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 10 μm.

[0086] Finally, obtain the anti-fatigue fracture high-entropy alloy fastener.

[0087] Example 4:

[0088] The preparation process of the anti-fatigue fracture high-entropy alloy fastener in this example includes the following steps:

[0089] Step 1: Make a Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 50 mm by melting in a furnace, and perform solution treatment and aging treatment. The solution temperature is 800 °C, and the holding time is 6 hours; the aging temperature is 500 °C, and the holding time is 5 hours.

[0090] Step 2: The rod after solution and aging treatment is made into a fastener substrate by hot forging and hot rolling. The forging temperature is 850 °C, and the rolling temperature is 350 °C; and polish the head of the fastener substrate.

[0091] Step 3: Deposit a bonding layer in an argon environment by arc ion plating technology under the conditions of 2 Pa and 150 V. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with (110) crystal plane preferred orientation. The nanocrystalline grain size is 20 nm, and the coating thickness is 80 nm.

[0092] Deposit a support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed. The modulation period is 20 nanometers, the thickness of a single Ni-Co-Fe-Mo-Al layer is 10 nanometers, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nanometers;

[0093] Deposit a piezoelectric functional layer under the conditions of 2 Pa and 10 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 4 at.%; the Fe content is 3 at.%; the Cr content is 3 at.%. The coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 1 micron;

[0094] Deposit a wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 0 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 10 microns;

[0095] Finally, obtain the anti-fatigue fracture high-entropy alloy fastener.

[0096] Example 5:

[0097] The preparation process of the anti-fatigue fracture high-entropy alloy fastener in this example includes the following steps:

[0098] Step 1: Make a Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 80 mm by melting in a furnace, and carry out solution and aging treatments. The solution temperature is 1000 °C, and the holding time is 10 hours; the aging temperature is 600 °C, and the holding time is 9 hours;

[0099] Step 2: The rod after solution and aging treatments is made into a fastener matrix by hot forging and hot rolling thread. The forging temperature is 900 °C, and the rolling thread temperature is 500 °C; and polish the head of the fastener matrix;

[0100] Step 3: Deposit a bonding layer by arc ion plating technology in an argon environment under the conditions of 2 Pa and 50 V. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with (110) crystal plane preferred orientation. The nanocrystalline grain size is 10 nanometers, and the coating thickness is 50 nanometers;

[0101] Deposit a support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. Intermittently introduce nitrogen to form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film. The modulation period is 30 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nm;

[0102] Deposit a piezoelectric functional layer under the conditions of 0.5 Pa and 10 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 5 at.%; the Fe content is 1 at.%; the Cr content is 1 at.%. The coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 1.5 μm;

[0103] Deposit a wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 0 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 μm;

[0104] Finally, obtain the anti-fatigue fracture high-entropy alloy fastener.

[0105] Comparative Example 1:

[0106] The preparation process of the fastener in this comparative example includes the following steps:

[0107] Step 1, melt the Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 100 mm, and perform solution and aging treatments. The solution temperature is 1000 °C, and the holding time is 10 hours; the aging temperature is 600 °C, and the holding time is 10 hours;

[0108] Step 2, the rod after solution and aging treatments is made into a fastener substrate by hot heading and hot rolling. The heading temperature is 900 °C, and the rolling temperature is 500 °C; and polish the head of the fastener substrate;

[0109] Step 3, deposit a bonding layer in an argon environment by arc ion plating technology under the conditions of 2 Pa and 150 V. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with a (110) crystal plane preferred orientation. The nanocrystalline grain size is 20 nm, and the coating thickness is 100 nm;

[0110] Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed. The modulation period is 30 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nm.

[0111] Deposit the piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 5 at.%, the Fe content is 0.5 at.%, and the Cr content is 10 at.%. The coating crystallization orientation is the (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 2 μm.

[0112] Deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 200 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 μm.

[0113] Comparative Example 2:

[0114] The preparation process of the fastener in this comparative example includes the following steps:

[0115] Step 1: Melt the Ni-Co-Fe-Mo-Al high-entropy alloy material in a furnace to make a rod with a diameter of 100 mm, and perform solution and aging treatments. The solution temperature is 1000 °C, and the holding time is 10 hours; the aging temperature is 600 °C, and the holding time is 10 hours.

[0116] Step 2: The rod after solution and aging treatments is made into a fastener substrate through hot upsetting and hot rolling. The upsetting temperature is 900 °C, and the rolling temperature is 500 °C; and polish the head of the fastener substrate.

[0117] Step 3: Deposit the bonding layer in an argon environment by arc ion plating technology under the conditions of 2 Pa and 150 V. The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with a (110) crystal plane preferred orientation. The nanocrystalline grain size is 20 nm, and the coating thickness is 100 nm.

[0118] Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed. The modulation period is 30 nm, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nm, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nm.

[0119] Deposit the piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloy. The V content is 5 at.%; the Fe content is 6 at.%; the Cr content is 10 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystal, and the columnar crystal diameter is 2 microns;

[0120] Deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 200 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 microns.

[0121] Comparative Example 3:

[0122] The preparation process of the fastener in this comparative example includes the following steps:

[0123] Step 1: Melt the Ni-Co-Fe-Mo-Al high-entropy alloy material into a rod with a diameter of 100 mm, and perform solution treatment and aging treatment. The solution temperature is 1000 °C, and the holding time is 10 hours; the aging temperature is 600 °C, and the holding time is 10 hours;

[0124] Step 2: The rod after solution and aging treatment is made into a fastener substrate by hot forging and hot rolling. The forging temperature is 900 °C, and the rolling temperature is 500 °C; and polish the head of the fastener substrate;

[0125] Step 3: Deposit the bonding layer in an argon environment by arc ion plating under the conditions of 2 Pa and 150 V; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystal bonding layer with (110) crystal plane preferred orientation, the nanocrystal grain size is 20 nanometers, and the coating thickness is 100 nanometers;

[0126] Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V, and form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film by intermittently introducing nitrogen; the modulation period is 30 nanometers, the thickness of the single-layer Ni-Co-Fe-Mo-Al layer is 20 nanometers, and the thickness of the single-layer Ni-Co-Fe-Mo-Al-N layer is 10 nanometers;

[0127] Deposit the piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloy. The V content is 5 at.%; the Fe content is 5 at.%; the Cr content is 0.5 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystal, and the columnar crystal diameter is 2 microns;

[0128] Deposit a wear-resistant electrode layer under the conditions of 3 Pa and 200 V in a nitrogen environment. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, with a contact resistance less than 100 ohms and a coating thickness of 20 microns.

[0129] Comparative Example 4:

[0130] The preparation process of the fastener in this comparative example includes the following steps:

[0131] Step 1: Melt the Ni-Co-Fe-Mo-Al high-entropy alloy material in a furnace to make a rod with a diameter of 100 mm, and perform solution and aging treatments. The solution temperature is 1000 °C, and the holding time is 10 hours; the aging temperature is 600 °C, and the holding time is 10 hours.

[0132] Step 2: The rod after solution and aging treatments is made into a fastener substrate through hot forging and hot rolling. The forging temperature is 900 °C, and the rolling temperature is 500 °C; and polish the head of the fastener substrate.

[0133] Step 3: Deposit a bonding layer in an argon environment using arc ion plating technology under the conditions of 2 Pa and 150 V; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with a (110) crystal plane preferred orientation, the nanocrystalline grain size is 20 nanometers, and the coating thickness is 100 nanometers.

[0134] Deposit a support layer in an argon + nitrogen environment using arc ion plating under the conditions of 3 Pa and 150 V, and form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film by intermittently introducing nitrogen; the modulation period is 30 nanometers, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nanometers, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nanometers.

[0135] Deposit a piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a V, Fe, Cr ternary alloy co-doped piezoelectric material, with a V content of 5 at.%; an Fe content of 5 at.%; a Cr content of 12 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 2 microns.

[0136] Deposit a wear-resistant electrode layer under the conditions of 3 Pa and 200 V in a nitrogen environment. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, with a contact resistance less than 100 ohms and a coating thickness of 20 microns.

[0137] Comparative Example 5:

[0138] The preparation process of the fastener in this example includes the following steps:

[0139] Step 1: The Ni-Co-Fe-Mo-Al high-entropy alloy material is melted in a furnace to make a rod with a diameter of 100 mm, and then solution treatment and aging treatment are carried out. The solution temperature is 1000 °C and the holding time is 10 hours; the aging temperature is 600 °C and the holding time is 10 hours.

[0140] Step 2: The rod after solution and aging treatment is made into a fastener substrate by hot forging and hot rolling thread. The forging temperature is 900 °C and the rolling thread temperature is 500 °C; and the head of the fastener substrate is polished.

[0141] Step 3: Under the conditions of 2 Pa and 150 V, the bonding layer is deposited in an argon environment by arc ion plating technology; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with (110) crystal plane preferred orientation. The grain size of the nanocrystals is 20 nm and the coating thickness is 100 nm.

[0142] Under the conditions of 3 Pa and 150 V, the support layer is deposited in an argon + nitrogen environment by arc ion plating. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed; the modulation period is 30 nm, the thickness of the single-layer Ni-Co-Fe-Mo-Al layer is 20 nm, and the thickness of the single-layer Ni-Co-Fe-Mo-Al-N layer is 10 nm.

[0143] Under the conditions of 2 Pa and 100 V, the piezoelectric functional layer is deposited. It is a piezoelectric material co-doped with V, Fe, and Cr ternary alloys. The V content is 6 at.%; the Fe content is 5 at.%; the Cr content is 10 at.%; the coating crystallization orientation is (002) crystallization orientation, and the crystal structure is columnar crystal. The diameter of the columnar crystal is 2 μm.

[0144] In a nitrogen environment, under the conditions of 3 Pa and 200 V, the wear-resistant electrode layer is deposited. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 μm.

[0145] Comparative Example 6:

[0146] The preparation process of the fastener in this comparative example includes the following steps:

[0147] Step 1: The Ni-Co-Fe-Mo-Al high-entropy alloy material is melted in a furnace to make a rod with a diameter of 100 mm, and then solution treatment and aging treatment are carried out. The solution temperature is 1000 °C and the holding time is 10 hours; the aging temperature is 600 °C and the holding time is 10 hours.

[0148] Step 2: The bars after solution failure treatment are made into fastener substrates through hot upsetting and hot rolling thread. The upsetting temperature is 900°C, and the rolling thread temperature is 500°C; and the head of the fastener substrate is polished;

[0149] Step 3: Under the conditions of 2 Pa and 150 V, the bonding layer is deposited in an argon environment by arc ion plating technology; the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline bonding layer with (110) crystal plane preferred orientation. The nanocrystalline grain size is 20 nanometers, and the coating thickness is 100 nanometers;

[0150] Under the conditions of 3 Pa and 150 V, the support layer is deposited in an argon + nitrogen environment by arc ion plating. By intermittently introducing nitrogen, a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nanomultilayer film is formed; the modulation period is 30 nanometers, the thickness of a single Ni-Co-Fe-Mo-Al layer is 20 nanometers, and the thickness of a single Ni-Co-Fe-Mo-Al-N layer is 10 nanometers;

[0151] Deposit the ZnO piezoelectric functional layer under the conditions of 2 Pa and 100 V;

[0152] Deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 200 V. The electrode material of the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 microns.

[0153] Comparative Example 7:

[0154] The preparation process of the fasteners in this comparative example includes the following steps:

[0155] Step 1: The FeCoCrNiMo high-entropy alloy material is melted in a furnace to make a bar with a diameter of 100 mm, and solution and failure treatments are carried out. The solution temperature is 1100°C, and the holding time is 8 hours; the failure temperature is 700°C, and the holding time is 6 hours;

[0156] Step 2: The bars after solution failure treatment are made into fastener substrates through hot upsetting and hot rolling thread. The upsetting temperature is 800°C, and the rolling thread temperature is 400°C; and the head of the fastener substrate is polished;

[0157] Step 3: Under the conditions of 2 Pa and 150 V, the bonding layer is deposited in an argon environment by arc ion plating technology; the bonding layer is a FeCoCrNiMo high-entropy nanocrystalline bonding layer with (111) crystal plane preferred orientation. The nanocrystalline grain size is 20 nanometers, and the coating thickness is 100 nanometers;

[0158] Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. By intermittently introducing nitrogen, a FeCoCrNiMo / FeCoCrNiMoN nanomultilayer film is formed. The modulation period is 30 nm, the thickness of a single FeCoCrNiMo layer is 20 nm, and the thickness of a single FeCoCrNiMoN layer is 10 nm.

[0159] Deposit the piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a ternary alloy co-doped piezoelectric material of V, Fe, and Cr. The V content is 5 at.%, the Fe content is 5 at.%, and the Cr content is 10 at.%. The coating crystallization orientation is the (002) crystallization orientation, the crystal structure is columnar crystals, and the columnar crystal diameter is 2 μm.

[0160] Deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 3 Pa and 200 V. The electrode material of the wear-resistant electrode layer is a FeCoCrNiMoN high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 μm.

[0161] Comparative Example 8:

[0162] The preparation process of the fastener in this comparative example includes the following steps:

[0163] Step 1: Melt the FeCoCrNiMo high-entropy alloy material into a rod with a diameter of 100 mm, and perform solution and aging treatments. The solution temperature is 900 °C, and the holding time is 8 hours; the aging temperature is 500 °C, and the holding time is 5 hours.

[0164] Step 2: The rod after solution and aging treatment is made into a fastener substrate by hot heading and hot rolling thread. The heading temperature is 850 °C, and the rolling thread temperature is 350 °C; and polish the head of the fastener substrate.

[0165] Step 3: Deposit the bonding layer in an argon environment by arc ion plating technology under the conditions of 2 Pa and 150 V. The bonding layer is a FeCoCrNiMo high-entropy nanocrystalline bonding layer with a preferred orientation of the (111) crystal plane. The nanocrystalline grain size is 20 nm, and the coating thickness is 100 nm.

[0166] Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 3 Pa and 150 V. By intermittently introducing nitrogen, a FeCoCrNiMo / FeCoCrNiMoN nanomultilayer film is formed. The modulation period is 30 nm, the thickness of a single FeCoCrNiMo layer is 20 nm, and the thickness of a single FeCoCrNiMoN layer is 10 nm.

[0167] Deposit the piezoelectric functional layer under the conditions of 2 Pa and 100 V. It is a ternary alloy co-doped piezoelectric material of V, Fe, and Cr. The V content is 5 at.%; the Fe content is 5 at.%; the Cr content is 10 at.%; the coating crystallization orientation is (002) crystallization orientation, the crystal structure is columnar crystal, and the columnar crystal diameter is 2 microns; deposit the wear-resistant electrode layer under the conditions of 3 Pa and 200 V in a nitrogen environment. The electrode material of the wear-resistant electrode layer is a FeCoCrNiMo high-entropy alloy ceramic conductive coating, the contact resistance is less than 100 ohms, and the coating thickness is 20 microns.

[0168] Next, conduct tensile strength, fatigue fracture strength, high and low temperature cycle performance, and piezoelectric performance tests on the fasteners obtained from the above 5 groups of examples and 8 groups of comparative examples.

[0169] Among them, for the high and low temperature cycle test, the low temperature test is that the fastener is placed in an environment of -30°C for 96 h and the recovery time at normal temperature is 2 h; the high temperature test is that the fastener is placed in an environment of +80°C for 96 h and the recovery time at normal temperature is 2 h; for the high temperature and high humidity cycle test, the fastener is placed in an environment of +60°C and 95% RH for 96 h and the recovery time at normal temperature is 2 h; for the temperature shock, -30°C / +80°C, 10 cycles of 1 h / 1 h, and the conversion time is less than 3 min. After the climate performance test, the adhesion of the fastener thin film device layer needs to be detected, and it is qualified when no peeling of the thin film coating is detected.

[0170] Table 1 Performance test results of fasteners in each group of examples and comparative examples

[0171]

[0172] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anti-fatigue fracture high-entropy alloy fastener, characterized in that, It includes a fastener base body, on one end face of which a stress sensor is provided, and the fastener base body is a Ni-Co-Fe-Mo-Al high-entropy alloy; The stress sensor includes a bonding layer, a support layer, a piezoelectric functional layer, and a wear-resistant electrode layer stacked from the inside to the outside. Among them, the bonding layer is a Ni-Co-Fe-Mo-Al high-entropy alloy layer, the support layer is a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer ceramic layer, the piezoelectric functional layer is a doped ZnO layer, and the wear-resistant electrode layer is a Ni-Co-Fe-Mo-Al-N high-entropy alloy conductive ceramic coating.

2. The anti-fatigue fracture high-entropy alloy fastener according to claim 1, wherein The structure of the fastener base body is a face-centered cubic structure, and its composition is Ni: 5-25 at.%, Co: 5-20 at.%, Fe: 20-40 at.%, Mo: 5-15 at.%, Al: 2-20 at.%; its crystal structure is polycrystalline, and the grain size is 5-30 microns.

3. The anti-fatigue fracture high-entropy alloy fastener according to claim 1, wherein, The piezoelectric functional layer is a V, Fe, Cr ternary alloy co-doped piezoelectric material, where the V content is 0-5 at.%, the Fe content is 1-5 at.%, and the Cr content is 1-10 at.%.

4. The high-entropy alloy fastener with anti-fatigue fracture according to claim 3, characterized in that, The coating crystallization orientation of the piezoelectric functional layer is the (002) crystallization orientation, and the crystal structure is columnar crystals, and the diameter of the columnar crystals is 0.5-2.0 microns.

5. The high-entropy alloy fastener with fatigue and fracture resistance according to claim 1, characterized in that The modulation period of the support layer is 15-30 nanometers, the thickness of the single-layer Ni-Co-Fe-Mo-Al layer is 10-20 nanometers, and the thickness of the single-layer Ni-Co-Fe-Mo-Al-N layer is 5-10 nanometers.

6. The anti-fatigue fracture high-entropy alloy fastener according to claim 1, wherein The contact resistance of the wear-resistant electrode layer is less than 100 ohms, and the coating thickness is 1-20 microns.

7. The high-entropy alloy fastener with anti-fatigue fracture according to claim 1, wherein The bonding layer is a Ni-Co-Fe-Mo-Al high-entropy nanocrystalline alloy coating with a preferred orientation of the (110) crystal plane, the grain size of the nanocrystals is 10-20 nanometers, and the coating thickness is 20-100 nanometers.

8. The high-entropy alloy fastener with anti-fatigue fracture according to claim 1, characterized in that, A groove is formed in the head of the fastener base body, and the stress sensor is arranged in the groove.

9. A method for preparing an anti-fatigue fracture high-entropy alloy fastener according to any one of claims 1-8, characterized in that, The heat treatment of the fastener base body is realized by solution treatment and aging. The solution treatment temperature is 800-1000 °C, and the holding time is 2-10 hours; the aging temperature is 400-600 °C, and the holding time is 4-10 hours.

10. The preparation method of the anti-fatigue fracture high-entropy alloy fastener according to claim 9, characterized in that, It includes the following steps: Step 1, melt the Ni-Co-Fe-Mo-Al high-entropy alloy material into a bar with a diameter of 8-100 mm, and perform solution treatment and aging; Step 2, the bar after solution treatment and aging is made into a fastener base body by hot forging and hot rolling thread. The forging temperature is 800-900 °C, and the rolling thread temperature is 300-500 °C; and polish the head of the fastener base body; Step 3, deposit the bonding layer in an argon environment by arc ion plating technology under the conditions of 1-2 Pa and 50-150 V; Deposit the support layer by arc ion plating in an argon + nitrogen environment under the conditions of 1-3 Pa and 50-150 V, and intermittently introduce nitrogen to form a Ni-Co-Fe-Mo-Al / Ni-Co-Fe-Mo-Al-N nano-multilayer film; Deposit the piezoelectric functional layer under the conditions of 0.5 - 2 Pa and 10 - 100 V; deposit the wear-resistant electrode layer in a nitrogen environment under the conditions of 1 - 3 Pa and 0 - 200 V to obtain the anti-fatigue fracture high-entropy alloy fastener.

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