A high-hardness nanocomposite structured high-entropy alloy coating and a method of preparing and hardening the same

Abstract

The application discloses a high-hardness nano-composite-structure high-entropy alloy coating and a preparation and hardening method thereof, and belongs to the technical field of sputtering plating. The method comprises the following steps: (1) ion etching is adopted to bombard a substrate by using a plasma, so that an activated etching substrate is obtained; subsequently, a hard coating is formed on the surface of the activated etching substrate by sputtering a high-entropy alloy as a target material by using a magnetron sputtering, so that a coated substrate is obtained; (2) the coated substrate is subjected to heat treatment to harden the surface coating, so that a high-hardness nano-composite-structure high-entropy alloy coating is obtained. The application has the advantages of simple process and high production efficiency, and the obtained high-hardness nano-composite-structure high-entropy alloy coating has high hardness, can effectively reduce friction damage, and prolongs the service life of a substrate material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sputtering coating, in particular to a high-hardness nano-composite high-entropy alloy coating and a preparation and hardening method thereof. BACKGROUND

[0002] Tools, machine parts and large facilities used in material processing and forming processes are subjected to serious tribological damage, which gradually and even catastrophically deteriorates the mechanical properties of the material surface, eventually leading to the failure of its applicability, causing huge waste of resources and economic losses. Therefore, improving the mechanical properties of mechanical equipment and parts and prolonging their service life have become urgent problems in modern industrial manufacturing.

[0003] Depositing a hard coating on the surface of a material can effectively improve the friction damage suffered by the material and prolong its service life. In addition, by combining basic material science principles with a wide variety of preparation process conditions through coating preparation technology, the comprehensive performance of the material can be further improved. Chemical vapor deposition (CVD) and physical vapor deposition (PVD) are currently the mainstream coating preparation methods. Coatings prepared by CVD technology have high bonding strength with the substrate, good chemical purity, and simple preparation process, and can be deposited on various complex-shaped parts (such as the inner wall of a pipe, a pore, etc.). However, the process of depositing a coating by CVD technology requires extremely high reaction temperatures (above 900℃), which causes problems such as grain growth in the coating and the substrate, restricting its further application. Compared with CVD technology, PVD technology can deposit coatings at relatively low temperatures (below 500℃), and the coatings prepared have a smooth surface, usually exhibit compressive stress inside, and have high mechanical strength, so it is widely used in the deposition of hard coatings. Hard coatings prepared by magnetron sputtering have nanoscale grain size, uniform microstructure, and low element segregation, and have excellent mechanical properties, so they dominate in the preparation of hard coatings by PVD technology.

[0004] High-entropy alloy is a new alloy system containing at least 5 elements. Compared with traditional alloy systems, high-entropy alloy has four unique effects, namely: high-entropy effect in thermodynamics; sluggish diffusion effect in kinetics; lattice distortion effect in structure; and "cocktail" effect in performance. Therefore, high-entropy alloy exhibits more excellent mechanical properties, wear resistance and thermal stability, and has rapidly become a hot spot of modern industrial manufacturing. In addition to bulk high-entropy alloys, the concept has been applied to hard coatings deposited by PVD technology, promoting the further development of high-hardness coatings.

[0005] The microstructure of high-entropy alloy hard coatings significantly impacts their performance, and different fabrication processes exert complex influences on the microstructure. To further improve the mechanical properties of hard coatings, it is crucial to analyze their hardening mechanism at the microstructure level and establish the correlation between process, structure, and performance—a matter of significant scientific importance. However, current research on the hardening mechanism of high-entropy alloy coatings deposited by magnetron sputtering is relatively limited. Therefore, analyzing the fine structure of high-entropy alloy coatings at the nanoscale, deeply revealing their hardening mechanism, and improving their mechanical properties has become a current research focus. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a method for preparing and hardening a high-hardness nanocomposite high-entropy alloy coating with simple process and high production efficiency is provided, comprising the following steps:

[0007] (1) Ion etching is used to bombard the substrate with plasma to obtain an activated etched substrate; then magnetron sputtering is used to sputter a hard coating on the surface of the activated etched substrate using a high-entropy alloy as the target material to obtain a coated substrate.

[0008] (2) The coating substrate is heat-treated to harden the surface coating, resulting in a high-hardness nanocomposite high-entropy alloy coating.

[0009] Preferably, the specific method of step (1) is as follows: remove impurities from the substrate surface, use ion etching, first place the substrate in a vacuum and at a certain temperature, then introduce argon gas and set the substrate bias voltage and duty cycle; argon gas is ionized under the action of arc power supply current to form Ar + Ion beam, with Ar + The substrate is bombarded with an ion beam to obtain an activated etched substrate. Argon gas is introduced again and the bias voltage and duty cycle of the substrate are set. A high-entropy alloy is used as the sputtering target and magnetron sputtering is employed to deposit the material in the sputtering target onto the surface of the activated etched substrate, thus obtaining a coated substrate.

[0010] More preferably, the temperature is 100-1300℃; in the ion etching, the gas pressure after argon gas is introduced is 0.5-11.0 Pa; in the magnetron sputtering, the gas pressure after argon gas is introduced is 0.5-11.5 Pa.

[0011] More preferably, in the ion etching, the substrate bias voltage is -200V to 50V, and the substrate duty cycle is 30% to 170%; in the magnetron sputtering, the substrate bias voltage is -300V to 10V, and the substrate duty cycle is 30% to 170%.

[0012] More preferably, the arc power supply current is 801120A.

[0013] Further preferably, the high-entropy alloy is an AlCrNbSiTi high-entropy alloy.

[0014] Further, in the AlCrNbSiTi high-entropy alloy, the atomic ratio of Al, Cr, Nb, Si and Ti is 34:22:11:11:22.

[0015] In order to regulate the microstructure of the coating, the present application designs the composition of the AlCrNbSiTi target material through theoretical calculation, regulates the microstructure of the AlCrNbSiTi hard coating by the method of theoretically guiding practice, and optimizes the performance of the coating. The present application calculates three phase structure prediction parameters of the high-entropy alloy system, reasonably designs the high-entropy alloy target material with large atomic size difference (delta), negative mixing enthalpy (Delta H 3ix ) and small mixing entropy (Delta S 3ix ) ratio (Omega) of Delta H 3ix , i.e. the atomic ratio of the AlCrNbSiTi high-entropy alloy is as described above. Under the above ratio, the strong chemical attraction caused by the extremely negative binary mixing enthalpy between Si atoms and Al, Cr, Nb and Ti atoms is fully utilized, and a high-hardness high-entropy alloy coating with a nano-composite structure of amorphous-nanocrystalline silicide is synthesized. Through high-temperature annealing treatment, the coating is further hardened, and the analysis by high-resolution transmission electron microscopy reveals that the existence of hard nanocrystalline silicide and its large precipitation after annealing treatment is the hardening mechanism of the coating.

[0016] Further preferably, the sputtering power of the magnetron sputtering is 500-1900 W.

[0017] Preferably, the specific method of step (2) is as follows: the coating substrate is placed in a vacuum environment, then inert gas is introduced as a protective gas, heated to a certain temperature, and annealing treatment is carried out at the temperature; after the annealing treatment is completed, the coating is hardened by natural cooling to room temperature, and a high-hard nano-composite structure high-entropy alloy coating is obtained.

[0018] Further preferably, the gas pressure after the inert gas is introduced is 0.5-11.0 Pa; and the heating rate is 3-15 ℃ / min.

[0019] Further preferably, the annealing treatment temperature is 600-1100 ℃, and the time is 2-15 h.

[0020] The present application can select appropriate processing parameters to meet the application requirements of different situations, and the process is flexible.

[0021] In the second aspect of the present application, a high-hard nano-composite structure high-entropy alloy coating is provided, which is prepared by the method of the first aspect of the present application.

[0022] Compared with the prior art, the application has the following advantages and beneficial effects:

[0023] The application provides a preparation method and a hardening method of a high-hardness nano-composite structure high-entropy alloy coating.

[0024] The application provides a high-hardness nano-composite structure high-entropy alloy coating. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The application provides a schematic diagram of a magnetron sputtering device used in the embodiment, wherein 1 represents a vacuum system, 2 represents a heater, 3 represents a gas pipeline, 4 represents a sample holder, 5 represents a magnetron sputtering power supply, 6 represents a sputtering target material, 7 represents an arc power supply, 8 represents an arc target material, and 9 represents a baffle.

[0026] Figure 2 In the application, (a) is the calculation result of the phase structure prediction parameters delta, delta H and omega of the AlCrNbSiTi high-entropy alloy system used when designing the sputtering target material composition; 3ix (b) is the binary mixing enthalpy between atoms in the AlCrNbSiTi high-entropy alloy sputtering target material; (c) is the phase structure corresponding to the delta-omega model and different delta-omega values; and (d) is the phase structure corresponding to the delta-delta H model and different delta-delta H values. 3ix 3ix

[0027] Figure 3 In the application, (a) is a surface topography diagram of the high-hardness nano-composite structure high-entropy alloy coating of Example 1; (b) is a three-dimensional geological topography diagram of the high-hardness nano-composite structure high-entropy alloy coating of Example 1; and (c) is a cross-sectional topography diagram of the high-hardness nano-composite structure high-entropy alloy coating of Example 1.

[0028] Figure 4 In the application, (a) is a microstructure diagram of the high-hardness nano-composite structure high-entropy alloy coating of Example 1; (b) is a Fourier transform (FFT) processed image of the A region in (a); (c) is an inverse Fourier transform (IFFT) processed image of the A region in (a); (d) is a Fourier transform (FFT) processed image of the B region in (a); and (e) is an inverse Fourier transform (IFFT) processed image of the B region in (a).

[0029] Figure 5 ​​In the figure, (a) and (b) are the microstructure diagram and selected electron diffraction pattern of the high-hardness nanocomposite high-entropy alloy coating of Example 1, respectively; (c) are the X-ray diffraction patterns of the coatings obtained in Example 1, Example 618 and Comparative Example 1.

[0030] Figure 6 The graph shows the variation of nanohardness and elastic modulus of the coatings obtained in Example 1, Example 618, and Comparative Example 1. Detailed Implementation

[0031] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0032] In the following embodiments:

[0033] The substrates are commercial single-crystal Si(100) wafers, 304 stainless steel wafers, and WC cemented carbide.

[0034] The arc target material is a commercially available Cr (99.99%) target;

[0035] The sputtering target is made by mixing powders of five elements, Al, Cr, Nb, Si and Ti, in an atomic ratio of 34:22:11:11:22 and then sintering them at 500℃ and 130MPa for 2 hours using the hot isostatic pressing method.

[0036] Example 1

[0037] A high-hardness nanocomposite high-entropy alloy coating is prepared by the following method:

[0038] (1) The substrate was ultrasonically cleaned for 103 minutes in acetone, ethanol, and deionized water respectively to remove dust, organic matter, and other stubborn contaminants from the substrate surface. After drying in a nitrogen atmosphere, it was quickly placed into a vacuum chamber to prevent recontamination. The substrate was then placed in a vacuum chamber as follows: Figure 1 The sample holder of the magnetron sputtering apparatus shown is positioned with the substrate parallel to the arc target and the sputtering target perpendicular to the arc target. The cooling system is activated, and a vacuum is drawn using the vacuum system. Simultaneously, the heater is turned on to adjust the vacuum level in the chamber to 2 × 10⁻⁶. -3 Pa, adjusted to 300℃; Ar gas was introduced into the venting pipe until the chamber pressure was 0.5 Pa; the substrate bias voltage was set to -150V and the duty cycle to 70%; the arc power supply was turned on with a current of 100A; under the action of voltage difference, an arc-enhanced glow discharge was formed, ionizing Ar into Ar... + Ar +ion beam under the potential difference, remove the oxide on the surface of the substrate and activate the surface to increase the adhesion between the substrate and the coating, obtain an activated etched substrate, in order to protect the substrate from being sputtered by Cr + influence, during the etching process, the arc target is provided with a baffle and the baffle is in a closed state, and Cr + is blocked; after the bombardment is completed, the arc power supply is turned off, the sample holder is rotated clockwise by 90°, the substrate is parallel to the sputtering target, the bias voltage and the duty cycle of the substrate are kept unchanged, Ar gas is introduced into the chamber to a pressure of 0.5 Pa, the magnetron sputtering power supply is turned on, the sputtering power is adjusted to 600 W, under the action of Ar gas flow and the magnetron sputtering power supply, the target material is sputtered and deposited on the surface of the activated etched substrate, the deposition time is controlled to form a sputtered coating with a thickness of 1.6 u3, after the preparation is completed, the magnetron sputtering device is turned off, and the chamber is naturally cooled to room temperature to obtain a coated substrate;

[0039] (2) The coated substrate is placed in a tube furnace, the vacuum degree in the tube furnace is adjusted to 3x10 -3 Pa, then Ar gas is introduced as a protective gas to a pressure of 0.5 Pa in the chamber; the temperature rising rate in the tube furnace is set to 3℃ / min, the temperature is raised to 700℃ and kept at this temperature for 2h for annealing treatment; after the annealing treatment is completed, the chamber is naturally cooled to room temperature, the hardening of the hard coating is completed, and a high-hardness nano-composite structure high-entropy alloy coating is obtained.

[0040] Example 2

[0041] A high-hardness nano-composite structure high-entropy alloy coating is made by the following method:

[0042] (1) The substrate is ultrasonically cleaned in acetone, ethanol and deionized water respectively to remove dust, organic matter and other stubborn contaminants on the surface of the substrate, then dried in a nitrogen atmosphere to prevent recontamination; the substrate is placed in the sample holder of the magnetron sputtering device as shown in Figure 1 , at this time the substrate is parallel to the arc target, and the sputtering target is perpendicular to the arc target; the cooling system is turned on, vacuum is pumped through the vacuum system, and the heater is turned on to adjust the vacuum degree in the chamber to 2x10 -3 Pa and the temperature to 250℃; Ar gas is introduced into the chamber through the gas pipeline to a pressure of 0.8 Pa, the substrate bias voltage is set to -100 V, the duty cycle is set to 50%, the arc power supply is turned on, and the arc current is 110 A; under the action of the potential difference, an arc-enhanced glow discharge is formed to ionize Ar + into Ar + , and an Ar + ion beam bombards the substrate under the potential difference, removes the oxide on the surface of the substrate and activates the surface to increase the adhesion between the substrate and the coating, obtains an activated etched substrate, in order to protect the substrate from being sputtered by CrThe etching process was affected by a baffle on the arc target, which was in a closed state. + The process involves blocking the flow of gas; after the bombardment ends, the arc power supply is turned off, and the sample holder is rotated 90° clockwise to make the substrate parallel to the sputtering target. The bias voltage and duty cycle of the substrate are kept constant, and Ar gas is introduced until the pressure in the chamber is 1.0 Pa. The magnetron sputtering power supply is turned on, and the sputtering power is adjusted to 900 W. Under the action of the Ar gas flow and the magnetron sputtering power supply, the target material is sputtered and deposited on the surface of the activated etched substrate. The deposition time is controlled to form a sputtered coating with a thickness of 1.2 μm. After the preparation is completed, the magnetron sputtering equipment is turned off and allowed to cool naturally to room temperature to obtain the coated substrate.

[0043] (2) Place the coated substrate in a tube furnace and adjust the vacuum level inside the tube furnace to 3×10⁻⁶. -3 Pa, then Ar gas is introduced as a protective gas until the pressure in the chamber is 0.5 Pa; the heating rate in the tube furnace is set to 4℃33i3, the temperature is raised to 900℃ and held at this temperature for 3h for annealing treatment; after the annealing treatment is completed, it is naturally cooled to room temperature to complete the hard coating hardening and obtain a high-hardness nanocomposite high-entropy alloy coating.

[0044] Example 3

[0045] A high-hardness nanocomposite high-entropy alloy coating is prepared by the following method:

[0046] (1) The substrate was ultrasonically cleaned for 103 minutes in acetone, ethanol, and deionized water respectively to remove dust, organic matter, and other stubborn contaminants from the substrate surface. After drying in a nitrogen atmosphere, it was quickly placed into a vacuum chamber to prevent recontamination. The substrate was then placed in a vacuum chamber as follows: Figure 1 The sample holder of the magnetron sputtering apparatus shown is positioned with the substrate parallel to the arc target and the sputtering target perpendicular to the arc target. The cooling system is activated, and a vacuum is drawn using the vacuum system. Simultaneously, the heater is turned on to adjust the vacuum level in the chamber to 2 × 10⁻⁶. -3 Pa, adjusted to 100℃; Ar gas is introduced into the venting pipe until the chamber pressure is 0.9 Pa; the substrate bias voltage is set to -200V and the duty cycle to 40%; the arc power supply is turned on with a current of 90A; under the action of voltage difference, an arc-enhanced glow discharge is formed, causing Ar to ionize into Ar. + Ar + An ion beam bombards a substrate under a potential difference, removing oxides from the substrate surface and activating the surface to increase the adhesion between the substrate and the coating, resulting in an activated etched substrate. This process is designed to protect the substrate from Cr sputtered from the arc target. + The etching process was affected by a baffle on the arc target, which was in a closed state. +Blocking; after the end of bombardment, the arc power is turned off, the sample holder is rotated 90° clockwise, the substrate is parallel to the sputtering target, the bias voltage and the duty cycle of the substrate are kept unchanged, Ar gas is introduced into the chamber to a pressure of 0.9 Pa, the magnetron sputtering power is turned on, the sputtering power is adjusted to 800 W, under the action of Ar gas flow and magnetron sputtering power, the target material is sputtered and deposited on the activated etched substrate surface, the deposition time is controlled to form a sputtering coating with a thickness of 1.0 u3, after the preparation is completed, the magnetron sputtering device is turned off, and the coating substrate is naturally cooled to room temperature.

[0047] (2) The coated substrate is placed in a tube furnace, the vacuum degree in the tube furnace is adjusted to 3×10 -3 Pa, then Ar gas is introduced as a protective gas to a pressure of 0.5 Pa in the chamber; the temperature rising rate in the tube furnace is set to 5℃ / min, the temperature is raised to 1000℃ and kept at this temperature for 4h for annealing treatment; after the annealing treatment is completed, the temperature is naturally cooled to room temperature, the hardening of the hard coating is completed, and a high-hardness nano-composite structure high-entropy alloy coating is obtained.

[0048] Example 4

[0049] (1) The substrate is ultrasonically cleaned in acetone, ethanol and deionized water respectively, and the dust, organic matter and other stubborn contaminants on the surface of the substrate are removed, then the substrate is dried in a nitrogen atmosphere and quickly loaded into a vacuum chamber to prevent recontamination; the substrate is placed in the sample holder of the magnetron sputtering device as shown in Figure 1 , at this time the substrate is parallel to the arc target, and the sputtering target is perpendicular to the arc target; the cooling system is turned on, the vacuum system is pumped, and the heater is turned on at the same time to adjust the vacuum degree in the chamber to 2×10 -3 Pa and the temperature to 150℃; Ar gas is introduced into the chamber through the gas pipeline to a pressure of 1.0 Pa, the substrate bias voltage is set to -50V, the duty cycle is set to 70%, the arc power is turned on, the arc power current is 120A, and the arc enhanced glow discharge is formed under the action of the potential difference to ionize Ar into Ar + , and the Ar + ion beam bombards the substrate under the action of the potential difference to remove the oxide on the surface of the substrate and activate the surface to increase the adhesion between the substrate and the coating, thereby obtaining an activated etched substrate; in order to protect the substrate from being affected by the sputtering of Cr + in the arc target, a baffle is arranged on the arc target during etching and the baffle is in a closed state. +Blocking; after the end of bombardment, the arc power is turned off, the sample holder is rotated 90° clockwise, the substrate is parallel to the sputtering target, the bias voltage and the duty cycle of the substrate are kept unchanged, Ar gas is introduced into the chamber to a pressure of 0.6 Pa, the magnetron sputtering power is turned on, the sputtering power is adjusted to 500 W, under the action of Ar gas flow and magnetron sputtering power, the target material is sputtered and deposited on the activated etched substrate surface, the deposition time is controlled to form a sputtering coating with a thickness of 1.8 u3, after the preparation is completed, the magnetron sputtering device is turned off, and the coating substrate is naturally cooled to room temperature.

[0050] (2) The coated substrate is placed in a tube furnace, the vacuum degree in the tube furnace is adjusted to 3x10 -3 Pa, then Ar gas is introduced as a protective gas to a pressure of 0.5 Pa in the chamber; the temperature rising rate in the tube furnace is set to 5℃ / min, the temperature is raised to 800℃ and kept at this temperature for 5h for annealing treatment; after the annealing treatment is completed, the temperature is naturally cooled to room temperature, the hardening of the hard coating is completed, and a high-hardness nanocomposite structure high-entropy alloy coating is obtained.

[0051] Example 5

[0052] (1) The substrate is ultrasonically cleaned in acetone, ethanol and deionized water respectively, and the dust, organic matter and other stubborn contaminants on the surface of the substrate are removed, then the substrate is dried in a nitrogen atmosphere and quickly loaded into a vacuum chamber to prevent recontamination; the substrate is placed in the sample holder of the magnetron sputtering device as shown in Figure 1 , at this time the substrate is parallel to the arc target, and the sputtering target is perpendicular to the arc target; the cooling system is turned on, the vacuum system is pumped, and the heater is turned on at the same time to adjust the vacuum degree in the chamber to 2x10 -3 Pa and the temperature to 200℃; Ar gas is introduced into the chamber through the gas pipeline to a pressure of 0.7 Pa, the substrate bias voltage is set to -150V and the duty cycle is set to 30%, the arc power is turned on, the arc power current is 80A, and the arc enhanced glow discharge is formed under the action of the potential difference to ionize Ar into Ar + , and the Ar + ion beam bombards the substrate under the action of the potential difference to remove the oxide on the surface of the substrate and activate the surface to increase the adhesion between the substrate and the coating, thereby obtaining an activated etched substrate; in order to protect the substrate from being affected by the sputtering of Cr + in the arc target, a baffle is provided on the arc target during etching and the baffle is in a closed state. +occlusion; after the bombardment is completed, the arc power is turned off, the sample holder is rotated 90° clockwise, the substrate is parallel to the sputtering target, the bias voltage and the duty cycle of the substrate are kept unchanged, Ar gas is introduced into the chamber to a pressure of 0.8 Pa, the magnetron sputtering power is turned on, the sputtering power is adjusted to 700 W, under the action of Ar gas flow and magnetron sputtering power, the target material is sputtered and deposited on the activated etched substrate surface, the deposition time is controlled to form a sputtering coating with a thickness of 2.0 u3, after the preparation is completed, the magnetron sputtering device is turned off, and the coating substrate is naturally cooled to room temperature.

[0053] (2) The coated substrate is placed in a tube furnace, the vacuum degree in the tube furnace is adjusted to 3x10 -3 Pa, then Ar gas is introduced as a protective gas to a pressure of 0.5 Pa in the chamber; the temperature rising rate in the tube furnace is set to 3℃ / min, the temperature is raised to 600℃ and kept at this temperature for 3h for annealing treatment; after the annealing treatment is completed, the temperature is naturally cooled to room temperature, the hardening of the hard coating is completed, and a high-hardness nanocomposite structure high-entropy alloy coating is obtained.

[0054] Example 6

[0055] This example is basically the same as Example 1, the only difference being that the annealing temperature in step (2) is 600℃.

[0056] Example 7

[0057] This example is basically the same as Example 1, the only difference being that the annealing temperature in step (2) is 800℃.

[0058] Example 8

[0059] This example is basically the same as Example 1, the only difference being that the annealing temperature in step (2) is 900℃.

[0060] Comparative Example 1

[0061] A high-entropy alloy coating is made by the following method:

[0062] The substrate is ultrasonically cleaned in acetone, ethanol and deionized water respectively to remove dust, organic matter and other stubborn contaminants on the surface of the substrate, and then dried in a nitrogen atmosphere to prevent recontamination; the substrate is placed in the sample holder of the magnetron sputtering device as shown in Figure 1 At this time, the substrate is parallel to the arc target, and the sputtering target is perpendicular to the arc target; the cooling system is turned on, vacuum is pumped through the vacuum system, and the heater is turned on to adjust the vacuum degree in the chamber to 2x10 -3Pa, adjusted to 300℃; Ar gas was introduced into the venting pipe until the chamber pressure was 0.5 Pa; the substrate bias voltage was set to -150V and the duty cycle to 70%; the arc power supply was turned on with a current of 100A; under the action of voltage difference, an arc-enhanced glow discharge was formed, ionizing Ar into Ar... + Ar + An ion beam bombards a substrate under a potential difference, removing oxides from the substrate surface and activating the surface to increase the adhesion between the substrate and the coating, resulting in an activated etched substrate. This process is designed to protect the substrate from Cr sputtered from the arc target. + The etching process was affected by a baffle on the arc target, which was in a closed state. + The process involves blocking the flow of gas; after the bombardment ends, the arc power supply is turned off, and the sample holder is rotated 90° clockwise to make the substrate parallel to the sputtering target. The bias voltage and duty cycle of the substrate are kept constant, and Ar gas is introduced until the pressure in the chamber is 0.5 Pa. The magnetron sputtering power supply is turned on, and the sputtering power is adjusted to 600 W. Under the action of the Ar gas flow and the magnetron sputtering power supply, the target material is sputtered and deposited on the surface of the activated etched substrate. The deposition time is controlled to form a sputtered coating with a thickness of 1.6 μm. After the preparation is completed, the magnetron sputtering equipment is turned off and allowed to cool naturally to room temperature to obtain a high-entropy alloy coating.

[0063] Test Example 1

[0064] The properties of the coatings obtained in the examples and test examples were tested. The microstructure of the coating obtained in Example 1 was observed using scanning electron microscopy, atomic force microscopy, and high-resolution transmission electron microscopy. The nanohardness and elastic modulus were measured by a nanoindenter based on the continuous stiffness method.

[0065] Depend on Figure 2 (a) It can be seen that the high-entropy alloy system designed in this invention has a large δ, a relatively negative ΔH3ix, and a small Ω; Figure 2 (b) It can be seen that Si atoms have a very negative binary enthalpy of mixing with Al, Cr, Nb and Ti atoms, which will cause a very strong chemical attraction and form silicides; Figure 2 (c) and (d) are based on data from the literature, obtained by Figure 2 From (c) and (d), we can see that, based on Figure 2 According to the theoretical calculation results in (a), the high-entropy alloy system designed in this invention will form an amorphous-nanocrystalline nanocomposite structure.

[0066] Depend on Figure 3 As shown in (a) and (b), the coating surface prepared in Example 1 is dense and smooth with a small roughness (Rq); Figure 3 (c) It can be seen that the coating prepared in Example 1 has no obvious defects and is tightly bonded to the substrate without obvious pores, indicating that the coating has good adhesion and can meet the application requirements.

[0067] Depend on Figure 4 (a) It can be seen that the coating prepared in Example 1 has an amorphous (region A) - nanocrystalline (region B) nanocomposite structure; Figure 4 (b) It can be seen that, Figure 4 (a) The FFT image of region A shows a diffuse ring corresponding to the amorphous phase, further confirming that region A as a whole is an amorphous phase; Figure 4 (c) It can be seen that, Figure 4 In (a), the IFFT image of region A does not show continuous lattice fringes, indicating an overall amorphous state. Some lattice fringes exist at a smaller scale (approximately 133), suggesting short-range ordered atomic arrangement in the coating around 133. Figure 5 The X-ray diffraction pattern results of the unannealed coating in (c) are consistent; Figure 4 (d) It can be seen that, Figure 4 (a) The FFT image of region B shows obvious diffraction spots of hexagonal silicide structure (Nb5Si3#08-0422, Ti5Si3#29-1362, Cr5Si3#09-0242), confirming that region B is a nanocrystalline silicide; Figure 4 (e) shows that, Figure 4 (a) The IFFT image of region B shows a typical hexagonal “ABAB” stacking pattern, further confirming that region B is a nanocrystalline silicide; Figure 4 It can be seen that the coating prepared in Example 1 has a nanocomposite structure of amorphous-nanocrystalline silicide, which is consistent with the theoretical calculation, confirming that the microstructure can be controlled according to theoretical calculation.

[0068] Depend on Figure 5 (a) It can be seen that after annealing the coating at 700°C under the conditions of Example 1, a large number of precipitates were observed in the amorphous matrix; Figure 5 (b) It can be seen that after annealing the coating at 700°C under the conditions of Example 1, the selected electron diffraction pattern shows that a large number of diffraction spots appeared in the amorphous diffraction ring, corresponding to... Figure 5 The precipitate in (a); by Figure 5 (c) It can be seen that, based on the conditions of Example 1, after annealing the coating at different temperatures, its X-ray diffraction patterns show that high-temperature annealing promotes the precipitation of silicides, and the intensity of the diffraction peaks is stronger with increasing annealing temperature (although the annealing process is carried out in a vacuum, some residual oxygen in the tube furnace caused a weak alumina diffraction peak to appear at 900°C); Figure 5 It can be seen that vacuum annealing can effectively control the microstructure of the coating in this invention.

[0069] Depend on Figure 6It can be seen that, based on the condition of example 1, the coating is annealed at different temperatures, which can effectively improve the hardness of the coating to realize its hardening, combined with Figure 5 It can be seen that the large precipitation of silicide is the mechanism of hardening of the coating.

[0070] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the existing technology according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A method for preparing and hardening a high-hardness nanocomposite high-entropy alloy coating, characterized in that, Includes the following steps: (1) Remove impurities from the substrate surface by ion etching. First, place the substrate in a vacuum and at a certain temperature, then introduce argon gas and set the substrate bias voltage and duty cycle. Argon gas is ionized under the influence of arc power supply current to form Ar + Ion beam, with Ar + Ion beam bombardment of the substrate yields an activated etched substrate; argon gas is introduced again and the bias voltage and duty cycle of the substrate are set. A high-entropy alloy is used as the sputtering target, and magnetron sputtering is employed to deposit the material in the sputtering target onto the surface of the activated etched substrate, thus obtaining a coated substrate. The high-entropy alloy is an AlCrNbSiTi high-entropy alloy, in which the atomic ratio of Al, Cr, Nb, Si, and Ti is 34:22:11:11:22; the temperature is 100~300℃; in the ion etching, the pressure after introducing argon gas is 0.5~1.0 Pa; in the magnetron sputtering, the pressure after introducing argon gas is 0.5~1.5 Pa; in the ion etching, the substrate bias voltage is -200~-50V, and the substrate duty cycle is 30%~70%; in the magnetron sputtering, the substrate bias voltage is -300~0V, and the substrate duty cycle is 30%~70%; the arc power supply current is 80~120A; and the sputtering power of the magnetron sputtering is 500~900W. (2) The coating substrate is placed in a vacuum environment, and then an inert gas is introduced as a protective gas. The temperature is raised to a certain temperature and annealed at that temperature. After the annealing is completed, it is naturally cooled to room temperature to complete the hardening of the coating and obtain a high-hardness nanocomposite high-entropy alloy coating. The annealing process is carried out at a temperature of 600~1000℃ for 2~5 hours. The pressure of the gas after the inert gas is introduced is 0.5~1.0 Pa; the heating rate is 3~5℃ / min.

2. A high-hardness nanocomposite high-entropy alloy coating, characterized in that: It is prepared by the method described in claim 1.

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