A Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity and its preparation method

Abstract

This invention relates to the field of thin film material preparation and surface engineering technology, specifically to a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity, and its preparation method. Addressing the problems of high surface roughness and low strain rate sensitivity in existing DC magnetron sputtering preparations of this system, an ultra-high vacuum radio frequency magnetron sputtering process is employed, using an equiatomic Ti... 16.67 Zr 16.67 Hf 16.67 Co 16.67 Ni 16.67 Cu 16.67 Using a substrate as the target material, by adjusting parameters such as substrate bias voltage of 50-150V and substrate temperature of 293K, the resulting film exhibits a surface roughness Ra as low as 0.2-0.4nm, a strain rate sensitivity index of 0.16-0.22, and uniform composition and stable structure. This invention can significantly improve the surface smoothness of thin films and is applicable to fields such as microelectronic packaging, MEMS devices, and protective coatings for micro / nano devices.

Description

Technical Field

[0001] This invention relates to the field of thin film material preparation and surface engineering technology, specifically to a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity, and its preparation method. Background Technology

[0002] High-entropy alloys are multi-principal-element alloy systems composed of five or more principal elements in equimolar or near-equimolar ratios. Due to their intrinsic high mixing entropy, they typically form simple solid solution phases. Under specific compositional and rapid cooling kinetics, high-entropy alloys can further form amorphous phases, i.e., high-entropy metallic glasses. These materials combine the compositional complexity of high-entropy alloys with the long-range disordered structure of metallic glasses, exhibiting excellent comprehensive performance in corrosion resistance, tribological properties, and surface smoothness, making them important candidate materials for advanced coatings and protective layers for micro / nano devices. The Ti-Zr-Hf-Co-Ni-Cu system has attracted widespread attention since its discovery of excellent mechanical properties in 2015. In this system, Ti, Zr, and Hf are refractory metal elements, while Co, Ni, and Cu are transition metal elements. The synergistic effect of the six principal elements endows the alloy with strong amorphous forming ability. Existing research shows that films from this system possess good structural stability and chemical homogeneity, making them suitable for microelectronic packaging protective layers, MEMS device coatings, and functional thin films.

[0003] Currently, the fabrication of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films mainly relies on DC magnetron sputtering technology. This technology suffers from several drawbacks when sputtering high-entropy alloy targets. The particle flux reaching the substrate and its energy distribution are relatively broad and lack uniformity, making it difficult to fully activate the surface diffusion behavior of adsorbed atoms. This results in surface roughness of the prepared films typically exceeding 0.6 nm, which is insufficient to meet the stringent low roughness requirements of micro / nano devices. Furthermore, the strain rate sensitivity index of films prepared using DC magnetron sputtering is relatively low (~0.1), leading to insufficient deformation adaptability in high-strain-rate service environments.

[0004] The patent with publication number CN117448653A proposes a high modulus and hardness crystalline Ti-Zr-Hf-Co-Ni-Cu high-entropy shape memory thin film and its preparation method. It adopts ultra-high vacuum DC magnetron sputtering technology, but it cannot solve the inherent problems of wide and uneven particle flux and energy distribution reaching the substrate during DC sputtering. It cannot fully activate the surface diffusion behavior of adsorbed atoms and cannot achieve ultra-low roughness control of the film surface. The film prepared by it cannot meet the stringent requirements of micro and nano devices for ultra-smooth surfaces.

[0005] The patent with publication number CN114561621A proposes a high-entropy metallic glass thin film, its preparation method and application. It targets a high-entropy metallic glass system composed of refractory metal ZrNbHfTaMo and noble metal Pt. It uses DC magnetron co-sputtering technology to prepare nano-multilayer structure thin films. It improves toughness by constructing nano-multilayer structures through noble metal doping. However, it cannot solve the inherent technical defects of DC sputtering Ti-Zr-Hf-Co-Ni-Cu thin films.

[0006] Patent CN118441245A discloses an oxygen-doped medium-entropy alloy / metallic glass nanolayered thin film and its preparation method. The prepared film is a FeCrNiO / TiVNbHfO oxygen-doped medium-entropy alloy / metallic glass nanolayered thin film. It adopts DC magnetron alternating sputtering technology and balances the strength and plasticity of the film through layered structure design. However, it does not conduct any research on the influence of the topological disorder of the amorphous structure on the strain rate sensitivity of the film or the control of the surface roughness by the substrate bias.

[0007] In contrast, radio frequency (RF) magnetron sputtering can generate more stable and spatially uniform plasma through an alternating electric field, thereby increasing plasma ionization density, narrowing the energy distribution of bombarding particles, and enhancing the surface diffusion ability of adsorbed atoms during film growth, achieving surface planarization. Furthermore, the higher degree of topological and chemical disorder retained in RF-deposited amorphous films increases the number density of nucleation sites in the shear transition region and broadens the thermal activation mechanism window for deformation, thus achieving higher strain rate sensitivity at the structural level. Additionally, by adjusting the substrate bias voltage in RF magnetron sputtering, the surface morphology and deformation behavior of the film can be precisely controlled.

[0008] The patent with publication number CN118814119A proposes a preparation technology and application of doped high-entropy alloy thin films. It uses radio frequency power supply for sputtering solid non-metallic targets, while the high-entropy alloy body film is still sputtered using DC power supply. Its core is to achieve the doping of non-metallic elements and optimize electrocatalytic performance and corrosion resistance. However, it does not study the influence of radio frequency magnetron sputtering on the amorphous structure, surface roughness, and strain rate sensitivity of high-entropy metallic glass thin films.

[0009] The patent with publication number CN119753477A proposes a multi-level nanostructured NiTiTaMoNbW high-entropy alloy thin film and its mechanical property control method. The research object is the NiTiTaMoNbW high-entropy alloy system. The scheme adopts RF and DC co-sputtering dual-target deposition and controls the crystalline phase volume ratio of the thin film through laser annealing. The core is to construct a multi-level nanostructure of crystalline / amorphous composite to balance strength and ductility. It only focuses on the yield strength and elastic strain of the thin film and does not involve the control of the surface roughness and strain rate sensitivity of the thin film.

[0010] In summary, there are currently no publicly available reports on the application of radio frequency magnetron sputtering systems in the preparation of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films. The influence of process parameters on the surface roughness and strain rate sensitivity of the thin films and the underlying physical mechanisms remain gaps to be filled in this field. Therefore, this invention is proposed. Summary of the Invention

[0011] To address the problems of the prior art, the present invention aims to provide a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity, and a method for its preparation. Specifically, the invention utilizes ultra-high vacuum radio frequency magnetron sputtering to prepare the Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity. By adjusting the substrate bias voltage during the preparation process, the invention solves the problems of high surface roughness and poor deformation adaptability under dynamic load environment in existing DC magnetron sputtering processes, achieving synergistic optimization of surface roughness and high strain rate sensitivity, and filling the application gap of radio frequency magnetron sputtering in this alloy system.

[0012] The technical solution of this invention is:

[0013] A Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity is disclosed. The high-entropy metallic glass thin film has a completely amorphous structure and is composed of Ti, Zr, Hf, Co, Ni and Cu in equal atomic ratios. The surface roughness Ra of the high-entropy metallic glass thin film is 0.2~0.4 nm, and the strain rate sensitivity index is 0.16~0.22.

[0014] The aforementioned low-roughness and high-strain-rate-sensitive Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass film contains a uniform distribution of six elements—Ti, Zr, Hf, Co, Ni, and Cu—with no second phase precipitation.

[0015] A method for preparing a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity includes the following steps:

[0016] (1) Target and substrate preparation

[0017] Single-crystal silicon wafers were selected as substrates and surface-treated to obtain single-sided polished single-crystal silicon wafers with a surface SiO2 thickness of 1~10µm. After surface cleaning and drying, the substrates were obtained after impurity removal. The polished surface of the substrates was placed downwards and horizontally inserted into an ultra-high vacuum magnetron sputtering system, with a baffle blocking the substrates. An equiatomic ratio Ti-Zr-Hf-Co-Ni-Cu alloy target prepared by powder metallurgy was fixed on the radio frequency power supply.

[0018] (2) Vacuuming and substrate pre-sputtering of magnetron sputtering equipment

[0019] A vacuum was created to a pressure of 10 using mechanical and molecular pumps. -5 Below Pa, high-purity argon gas is introduced at a flow rate of 15~40 sccm to maintain the gas pressure in the chamber at 0.3~0.7 Pa, and glow discharge cleaning is performed for 20~70 min; while maintaining the argon gas supply, the sputtering power is adjusted to 120~220W, and pre-sputtering is performed for 20~60 min to remove impurities from the target surface.

[0020] (3) Radio frequency magnetron sputtering coating

[0021] After pre-sputtering, maintain the working pressure in the ultra-high vacuum magnetron sputtering system at 0.7~0.9 Pa, the argon flow rate at 20~40 sccm, adjust the sputtering power to 120~220 W, adjust the substrate bias voltage to -50~-150 V, adjust the substrate temperature to 293 K, remove the baffle above the substrate to start formal sputtering, and simultaneously turn on the substrate 360° rotation switch, set the rotation speed to 30~60 rpm, and continue sputtering for 1~3 h. Cool with the furnace to obtain a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass film with low roughness and high strain rate sensitivity.

[0022] The method for preparing the low roughness and high strain rate sensitivity Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass film, in step (1), the size of the single crystal silicon wafer is 20mm×20mm; the surface cleaning is to use acetone for sonication for more than 40 minutes and alcohol for sonication for more than 40 minutes in sequence, and finally rinse with deionized water until the surface is clean; the drying is to use argon gas flow drying.

[0023] In the preparation method of the low roughness and high strain rate sensitivity Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film, in step (2), the high-purity argon gas conforms to the national standard GB / T4842-2017, with argon gas volume purity >99.999%, nitrogen content <5ppm, oxygen content <2ppm, hydrogen content <1ppm, total carbon content based on methane <2ppm, and moisture content <4ppm.

[0024] The design concept of this invention is:

[0025] This invention addresses the inherent technical deficiencies of existing DC magnetron sputtering technology in the preparation of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films. Based on plasma physics characteristics, it proposes a technical solution that replaces DC magnetron sputtering with radio frequency (RF) sputtering as the deposition method. This significantly reduces the film roughness and improves strain rate sensitivity. The high-entropy metallic glass thin film is composed of Ti, Zr, Hf, Co, Ni, and Cu in equiatomic ratios. The core design concept of this invention lies in using an alternating RF electric field to drive plasma discharge instead of a constant DC electric field. This fundamentally alters the flux uniformity and energy distribution characteristics of particles reaching the substrate, thereby independently controlling the two mutually constraining processes of surface densification and structural amorphization. Simultaneously, the high degree of topological and chemical disorder maintained by the RF deposition conditions helps increase the number density of nucleation sites in the shear transition region, broadening the thermal activation mechanism window for deformation and providing a structural basis for further improving the strain rate sensitivity of the thin film. This invention regulates the surface morphology and deformation behavior of the thin film by adjusting the substrate bias voltage during the preparation process, thereby achieving a synergistic improvement in surface roughness and strain rate sensitivity. It breaks through the performance bottleneck of existing DC magnetron sputtering technology in the preparation of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films, and provides a new technical path for the controllable preparation of high-performance high-entropy metallic glass thin films.

[0026] The advantages and beneficial effects of this invention are as follows:

[0027] 1. This invention is the first to apply a radio frequency magnetron sputtering system to the preparation of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films, effectively solving the process stability problem of DC magnetron sputtering on high-entropy alloy targets, and expanding the preparation technology path of thin films in this system.

[0028] 2. Under all deposition conditions, the thin films prepared by this invention maintain a complete amorphous structure, and the six elements are evenly distributed, ensuring that the composition of the thin film is similar to that of the target material. The process has good repeatability and strong composition controllability.

[0029] 3. By optimizing the substrate bias, this invention can obtain an ultra-smooth film with a surface roughness Ra as low as 0.2~0.4nm, which is 1.5~3 times lower than that of the same composition film sputtered by DC magnetron sputtering. It is the lowest roughness among the Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films reported to date, and is significantly better than the same system film sputtered by DC sputtering.

[0030] 4. The strain rate sensitivity (strain rate sensitivity index) of the thin film prepared by the present invention is 0.16~0.22, which is much higher than the reported values ​​of DC sputtered Ti-Zr-Hf-Co-Ni-Cu thin films and most metal thin films. This indicates that the radio frequency magnetron sputtering process endows the thin film with excellent deformation adaptability and can effectively cope with dynamic loads and impact environments.

[0031] 5. The method for preparing high-entropy metallic glass thin films by radio frequency magnetron sputtering of the present invention can be applied in the field of surface protection and functional coating of micro and nano devices, providing theoretical and technical support for improving the surface quality and deformation resistance of high-entropy metallic glass thin films. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. It can be seen that the following drawings are only a part of the experimental embodiments. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 The images shown are backscattered scanning electron microscopy images of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of -50V, -100V, and -150V, as shown in the examples.

[0034] Figure 2 The X-ray diffraction patterns of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of -50V, -100V, and -150V are shown in the examples.

[0035] Figure 3 The images shown are high-resolution transmission electron microscopy (a) and corresponding Fourier transform images (b) of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and a substrate bias voltage of 0 to -150V in the examples.

[0036] Figure 4 The images show the three-dimensional morphology of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of 0V, -50V, -100V, and -150V in the examples.

[0037] Figure 5The figure shows a comparison of the stress-strain rate relationship curves between the hardness of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of -50V, -100V, and -150V, and films of the same composition prepared by DC magnetron sputtering.

[0038] Figure 6 The images show a comparison of the strain rate sensitivity indices between Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of -50V, -100V, and -150V, and other metallic glass films prepared by DC magnetron sputtering. Detailed Implementation

[0039] In its specific implementation, the method for preparing the Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film of this invention employs radio frequency magnetron sputtering technology. By controlling the substrate bias voltage, the roughness of the thin film is significantly reduced and the strain rate sensitivity index is improved. The composition of the high-entropy metallic glass thin film is Ti with an equiatomic ratio. 16.67 Zr 16.67 Hf 16.67 Co 16.67 Ni 16.67 Cu 16.67 (at.%).

[0040] Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films were prepared using radio frequency magnetron sputtering. Specific parameters were as follows: the working pressure within the ultra-high vacuum magnetron sputtering system was 0.7–0.9 Pa; the argon flow rate was 20–40 sccm; the sputtering power was adjusted to 120–220 W; the substrate bias voltage was adjusted to -50–-150 V; the substrate temperature was adjusted to 293 K; the substrate was rotated 360°; and the substrate rotation speed was set to 30–60 rpm to maintain sputtering uniformity. The sputtering time was 1–3 h, followed by furnace cooling, resulting in Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. It should be noted that preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films within the above parameter range effectively ensures that the films possess ultra-low roughness and a high strain rate sensitivity index. In other embodiments of this invention, the process parameters can be adjusted as needed.

[0041] 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. It is obvious that what is described is only a part of the embodiments, and not all of them. Below, the low-roughness and high-strain-rate-sensitive Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film provided by the embodiments of the present invention will be specifically described.

[0042] Example 1

[0043] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity, which is obtained through the following preparation and heat treatment process:

[0044] (1) Prepare the target material and substrate using powder metallurgy.

[0045] A single-crystal silicon wafer was selected as the substrate and surface-treated to obtain a single-sided polished single-crystal silicon wafer with a 5µm thick SiO2 layer. The SiO2 layer enhances the adhesion between the substrate and the thin film, preventing film detachment. After surface cleaning, the wafer was dried to obtain a cleaned substrate. The dimensions of the single-crystal silicon wafer were 20mm × 20mm × 525μm (thickness). Surface cleaning involved ultrasonication with acetone for 60 minutes, followed by ultrasonication with alcohol for 60 minutes, and finally rinsing with deionized water until the surface was clean. The wafer was then dried using an argon gas flow. The cleaned and dried substrate was placed in a mold with the polished surface facing down and horizontally inserted into an ultra-high vacuum magnetron sputtering system, with a baffle blocking the substrate. An equiatomic ratio Ti-Zr-Hf-Co-Ni-Cu alloy target prepared using powder metallurgy was fixed onto the radio frequency power supply.

[0046] (2) Evacuate the magnetron sputtering equipment and pre-sputter the substrate.

[0047] A vacuum was created to a pressure of 10 using mechanical and molecular pumps. -5 Below Pa, high-purity argon gas is introduced at a flow rate of 20 sccm to maintain the gas pressure in the chamber at 0.5 Pa for glow discharge cleaning for 30 min; while maintaining the argon gas supply, the sputtering power is adjusted to 150 W, and after pre-sputtering for 30 min, surface impurities on the target are removed.

[0048] (3) Applying radio frequency magnetron sputtering for formal film deposition

[0049] After pre-sputtering, the working pressure inside the ultra-high vacuum magnetron sputtering system was maintained at 0.8 Pa, the argon flow rate at 25 sccm, the sputtering power was adjusted to 200 W, the substrate bias voltage was adjusted to -50 V, and the substrate temperature was adjusted to 293 K. The baffle above the substrate was removed to begin formal sputtering. At the same time, the substrate 360° rotation switch was turned on, and the rotation speed was set to 40 rpm to maintain sputtering uniformity. Sputtering continued for 1.5 h, followed by furnace cooling, to obtain a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass film with low roughness and high strain rate sensitivity. The final film roughness was 0.27 nm, and the strain rate sensitivity index was 0.20.

[0050] Example 2

[0051] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0052] In step (3), after pre-sputtering, the working pressure inside the ultra-high vacuum magnetron sputtering system is maintained at 0.8 Pa, the argon flow rate is 30 sccm, the sputtering power is adjusted to 150 W, the substrate bias voltage is adjusted to -100 V, the substrate temperature is adjusted to 293 K, the baffle above the substrate is removed to start formal sputtering, and the substrate 360° rotation switch is turned on at the same time, the rotation speed is set to 40 rpm to maintain the uniformity of sputtering. Sputtering continues for 2 hours, followed by furnace cooling. The final film roughness is 0.26 nm, and the strain rate sensitivity index is 0.22.

[0053] Example 3

[0054] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0055] In step (3), after the pre-sputtering is completed, the working pressure in the cavity of the ultra-high vacuum magnetron sputtering system is maintained at 0.75 Pa, the argon flow rate is 40 sccm, the sputtering power is adjusted to 180 W, the substrate bias voltage is adjusted to 0 V, the substrate temperature is adjusted to 423 K, the baffle above the substrate is removed to start the formal sputtering, and at the same time the substrate 360° rotation switch is turned on and the rotation speed is set to 30 rpm to maintain the uniformity of sputtering. Sputtering is continued for 1 hour and cooled with the furnace. The final film roughness is 0.8 nm and the strain rate sensitivity index is 0.17.

[0056] In this embodiment, the substrate temperature was increased from 293K to 423K. The film roughness was still 0.8nm under 0V bias, which is much higher than the roughness range of 0.2~0.4nm under the condition of -50~-150V / 293K of the present invention. The high temperature of 423K slightly increased the strain rate sensitivity index of the film to 0.17, but also led to a significant increase in roughness, which could not meet the stringent requirements of micro and nano devices.

[0057] Example 4

[0058] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0059] In step (3), after pre-sputtering, the working pressure in the cavity of the ultra-high vacuum magnetron sputtering system is maintained at 0.8 Pa, the argon flow rate is 25 sccm, the sputtering power is adjusted to 120 W, the substrate bias voltage is adjusted to -100 V, the substrate temperature is adjusted to 293 K, the baffle above the substrate is removed to start formal sputtering, and the substrate 360° rotation switch is turned on at the same time, the rotation speed is set to 30 rpm to maintain the uniformity of sputtering, and sputtering is continued for 1.2 h. After cooling with the furnace, the final film roughness is 0.28 nm and the strain rate sensitivity index is 0.21.

[0060] Example 5

[0061] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0062] In step (3), after pre-sputtering, the working pressure in the cavity of the ultra-high vacuum magnetron sputtering system is maintained at 0.85 Pa, the argon flow rate is 35 sccm, the sputtering power is adjusted to 220 W, the substrate bias voltage is adjusted to -70 V, the substrate temperature is adjusted to 293 K, the baffle above the substrate is removed to start formal sputtering, and the substrate 360° rotation switch is turned on at the same time, the rotation speed is set to 30 rpm to maintain the uniformity of sputtering, and sputtering is continued for 1.2 h. After cooling with the furnace, the final film roughness is 0.30 nm and the strain rate sensitivity index is 0.17.

[0063] Example 6

[0064] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0065] In step (3), after pre-sputtering, the working pressure in the cavity of the ultra-high vacuum magnetron sputtering system is maintained at 0.7 Pa, the argon flow rate is 30 sccm, the sputtering power is adjusted to 160 W, the substrate bias voltage is adjusted to 0 V, the substrate temperature is adjusted to 293 K, the baffle above the substrate is removed to start formal sputtering, and the substrate 360° rotation switch is turned on at the same time, the rotation speed is set to 35 rpm to maintain the uniformity of sputtering, and sputtering is continued for 1.5 h. After cooling with the furnace, the final film roughness is 1.05 nm and the strain rate sensitivity index is 0.12.

[0066] In this embodiment, at the same 293K room temperature substrate temperature and 0V without negative bias, the surface roughness of the thin film is as high as 1.05nm, which not only far exceeds the roughness range of 0.2~0.4nm of this invention, but also fails to reach the conventional level of 0.6nm of existing DC magnetron sputtering. Radio frequency magnetron sputtering cannot fully activate the surface diffusion ability of adsorbed atoms and cannot achieve surface smoothing. At the same 293K substrate temperature and 0V without negative bias, the strain rate sensitivity index of the thin film is only 0.12, which is basically the same as the conventional level (~0.1) of the same system thin film of existing DC magnetron sputtering. It cannot solve the problems of low strain rate sensitivity and poor deformation adaptability under dynamic load in the prior art.

[0067] Example 7

[0068] This embodiment provides a process for preparing Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films with low roughness and high strain rate sensitivity. The only difference between this process and Example 1 is that:

[0069] In step (3), after the pre-sputtering is completed, the working pressure in the cavity of the ultra-high vacuum magnetron sputtering system is maintained at 0.75 Pa, the argon flow rate is 35 sccm, the substrate bias voltage is adjusted to -150 V, the sputtering power is adjusted to 170 W, the substrate temperature is adjusted to 293 K, the baffle above the substrate is removed to start the formal sputtering, and the substrate 360° rotation switch is turned on at the same time, the rotation speed is set to 40 rpm to maintain the uniformity of sputtering. Sputtering is continued for 2 hours, and the film is cooled with the furnace. The final film roughness is 0.35 nm and the strain rate sensitivity index is 0.21.

[0070] Reference Figure 1 As shown, the Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering at a substrate temperature of 293 K and substrate bias voltages of -50 V, -100 V, and -150 V exhibit uniform microstructures and no second-phase precipitation. Furthermore, energy dispersive spectroscopy analysis revealed the following average compositions of the films:

[0071] Ti 16.8±0.02 Zr 17.1±0.04 Hf 16.4±0.03 Co 16.8±0.01 Ni16.7±0.02 Cu 16.2±0.05 ;

[0072] Ti 16.7±0.02 Zr 16.6±0.03 Hf 16.4±0.04 Co 17.0±0.02 Ni 17.0±0.03 Cu 16.3±0.05 ;

[0073] Ti 16.8±0.02 Zr 16.9±0.01 Hf 16.5±0.02 Co 16.5±0.03 Ni 16.9±0.03 Cu 16.4±0.02 ;

[0074] The composition of the target material is similar to that of the Ti-Zr-Hf-Co-Ni-Cu alloy with the same atomic ratio, indicating that radio frequency magnetron sputtering is an effective method for stably preparing high-quality Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films.

[0075] Reference Figure 2 As shown, the X-ray diffraction patterns of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering at a substrate temperature of 293K and substrate bias voltages of -50V, -100V, and -150V all exhibit broad "bun-shaped" diffraction peaks, indicating that the films all exhibit typical amorphous structural characteristics.

[0076] Reference Figure 3 As shown, high-resolution transmission electron microscopy (TEM) images of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by radio frequency magnetron sputtering at a substrate temperature of 293 K and substrate bias voltages of -50 V, -100 V, and -150 V all show that the atoms are randomly arranged and no lattice fringes are formed. The Fourier transform images also show typical amorphous ring characteristics, further illustrating that all thin films are amorphous structures. Figure 2 The results were consistent.

[0077] Reference Figure 4As shown, under the process conditions of substrate temperatures of 293K, 423K, and 523K, and substrate bias voltages of 0V, -50V, -100V, and -150V, the three-dimensional surface morphology test results of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by radio frequency magnetron sputtering technology show that when the substrate temperature is 293K and the substrate bias voltage is in the range of -50V to -150V, the peak-valley height difference of the film surface is less than 2.5nm, and the corresponding surface roughness is as low as 0.2~0.4nm, exhibiting excellent surface smoothness. In contrast, when the substrate bias voltage is 0V, the peak-valley height difference of the film surface increases to about 4.5nm, and the surface roughness is as high as 1.05nm; when the substrate temperature is increased to 423K or 523K, the peak-valley height difference of the film surface exceeds 3nm, and the surface roughness increases accordingly to 0.7~0.8nm. The above results indicate that the synergistic effect of appropriate negative bias voltage and low substrate temperature is the key process condition for obtaining ultra-low surface roughness.

[0078] Reference Figure 5 As shown, the strain rate sensitivity index of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by radio frequency magnetron sputtering is 0.16~0.22, which is much higher than that of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films prepared by DC magnetron sputtering. This is because the uniform plasma environment formed by radio frequency magnetron sputtering allows the film to retain a higher degree of topological and chemical disorder during deposition. The completely amorphous structure significantly increases the number density of nucleation sites in the shear transition region, enabling the film to activate more shear transition region cooperative motion under external load, thereby broadening the dominant window of the thermally activated deformation mechanism. In contrast, the bias-induced nanocrystalline / amorphous dual-phase structure in DC magnetron sputtering films introduces structural inhomogeneities such as grain boundaries, inhibiting the uniform distribution and thermal activation of the shear transition region, thus significantly limiting its strain rate sensitivity index.

[0079] Reference Figure 6 As shown, the Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film prepared by radio frequency magnetron sputtering in this invention exhibits a strain rate sensitivity index significantly higher than that of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin films prepared by DC magnetron sputtering and other metallic glass thin films. This demonstrates that the thin film prepared by this invention achieves a dual improvement in the number density of nucleation sites in the shear transition region and the ability to undergo thermally activated deformation within a completely amorphous structural framework, resulting in a strain rate sensitivity index that is among the leading levels in similar metallic glass thin film systems, demonstrating significant technical superiority and application competitiveness.

[0080] The results show that under a negative bias voltage of -50 to -150V, the film roughness can be as low as 0.2nm, which is more than 3 times lower than that under a 0V bias voltage. Within the specific negative bias voltage range of -50 to -150V, ultra-smooth and dense film surface is achieved by controlling the energy of ion bombardment. Increasing the substrate temperature will exacerbate the aggregation of adsorbed atoms and surface undulations. Even if the atomic diffusion ability is improved by high temperature, the surface smoothing effect brought about by the negative bias voltage cannot be achieved. Instead, it will destroy the surface smoothness. Choosing a substrate temperature of 293K room temperature, combined with a negative bias voltage of -50 to -150V, is the preferred process combination to achieve ultra-low roughness. This invention fills the technical gap in the application of radio frequency magnetron sputtering systems to the preparation of Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass films, clarifies the influence law and physical mechanism of process parameters on film surface roughness and strain rate sensitivity, and achieves synergistic optimization of film surface roughness and high strain rate sensitivity, breaking through the performance bottleneck of existing DC magnetron sputtering technology in the preparation of films in this system.

[0081] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity, characterized in that, The high-entropy metallic glass thin film has a completely amorphous structure and is composed of Ti, Zr, Hf, Co, Ni and Cu in equal atomic ratios. The surface roughness Ra of the high-entropy metallic glass thin film is 0.2~0.4 nm and the strain rate sensitivity index is 0.16~0.

22.

2. The low-roughness and high-strain-rate-sensitive Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film according to claim 1, characterized in that, In the high-entropy metallic glass thin film, the six elements Ti, Zr, Hf, Co, Ni and Cu are uniformly distributed, and no second phase is precipitated.

3. A method for preparing a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Target and substrate preparation Single-crystal silicon wafers were selected as substrates and surface-treated to obtain single-sided polished single-crystal silicon wafers with a surface SiO2 thickness of 1~10µm. After surface cleaning and drying, the substrates were obtained after impurity removal. The polished surface of the substrates was placed downwards and horizontally inserted into an ultra-high vacuum magnetron sputtering system, with a baffle blocking the substrates. An equiatomic ratio Ti-Zr-Hf-Co-Ni-Cu alloy target prepared by powder metallurgy was fixed on the radio frequency power supply. (2) Vacuuming and substrate pre-sputtering of magnetron sputtering equipment The vacuum is drawn to 10 -5 When the pressure is below 1 Pa, high-purity argon is introduced at a flow rate of 15-40 sccm, the pressure in the cavity is kept at 0.3-0.7 Pa, and glow cleaning is performed for 20-70 min; the argon introduction is kept, the sputtering power is adjusted to 120-220 W, and pre-sputtering is performed for 20-60 min to remove impurities on the surface of the target material; (3) Radio frequency magnetron sputtering coating After pre-sputtering, maintain the working pressure in the ultra-high vacuum magnetron sputtering system at 0.7~0.9 Pa, the argon flow rate at 20~40 sccm, adjust the sputtering power to 120~220 W, adjust the substrate bias voltage to -50~-150 V, adjust the substrate temperature to 293 K, remove the baffle above the substrate to start formal sputtering, and simultaneously turn on the substrate 360° rotation switch, set the rotation speed to 30~60 rpm, and continue sputtering for 1~3 h. Cool with the furnace to obtain a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass film with low roughness and high strain rate sensitivity.

4. The method for preparing a Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film with low roughness and high strain rate sensitivity according to claim 3, characterized in that, In step (1), the size of the single crystal silicon wafer is 20mm×20mm; the surface cleaning is performed by ultrasonication with acetone for more than 40 minutes and ultrasonication with alcohol for more than 40 minutes in sequence, and finally rinsing with deionized water until the surface is clean; the drying is performed by argon gas flow drying.

5. The method for preparing a low-roughness and high-strain-rate-sensitive Ti-Zr-Hf-Co-Ni-Cu high-entropy metallic glass thin film according to claim 3, characterized in that, In step (2), the high-purity argon gas conforms to the national standard GB / T4842-2017, with a volume purity of >99.999%, nitrogen content <5ppm, oxygen content <2ppm, hydrogen content <1ppm, total carbon content based on methane <2ppm, and moisture content <4ppm.

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