CN113235051A

CN113235051A - Nano biphase high-entropy alloy film and preparation method thereof

Info

Publication number: CN113235051A
Application number: CN202110512506.0A
Authority: CN
Inventors: 姜欣; 李延涛; 曾小康; 刘茂; 冷永祥
Original assignee: Southwest Jiaotong University
Current assignee: Southwest Jiaotong University
Priority date: 2021-05-11
Filing date: 2021-05-11
Publication date: 2021-08-10
Anticipated expiration: 2041-05-11
Also published as: CN113235051B

Abstract

The invention discloses a preparation method of a nano dual-phase high-entropy alloy film. The preparation method includes two steps of substrate pretreatment and high-power pulse magnetron sputtering deposition. Using high-power pulsed magnetron sputtering technology, the splicing target of five metal elements including Cu is used as the target, high-purity Ar is used as the working gas, a negative bias voltage is applied to the pre-treated substrate, a target voltage is applied to the splicing target, and a nano dual-phase high-entropy alloy film containing an FCC matrix phase and a copper-rich BCC nano-phase is deposited on the surface of the substrate. The film not only embodies the high solid solution strengthening characteristics of the high-entropy alloy film, but also introduces a large number of phase interfaces through the precipitation of the copper-rich phase, so that it has an interface strengthening mechanism. Its hardness is up to 13GPa, and due to its excellent toughness, it can play a good protective effect on the substrate working in a high-load, high-friction environment, and has good application value.

Description

Nano biphase high-entropy alloy film and preparation method thereof

Technical Field

The invention relates to the field of high-entropy alloy materials, in particular to a preparation method of a CuNiTiNbCr nano two-phase high-entropy alloy film.

Background

The high-entropy alloy film is used as a branch of the high-entropy alloy, the concept of the high-entropy alloy film is similar to that of the high-entropy alloy, namely the high-entropy alloy film comprises five or more elements, and the atomic percent of each element is 5-35%. The high-entropy alloy film has excellent performances of high hardness, high toughness, chemical corrosion resistance, wear resistance, irradiation resistance and the like, and is a novel hard film. The excellent performances enable the fuel to have wide application prospects in the fields of seawater corrosion, high-temperature wear resistance, accident fault-tolerant fuel cladding films and the like. At present, the preparation method of the high-entropy alloy film mainly comprises magnetron sputtering, multi-arc ion plating, thermal spraying, laser cladding and the like.

The high-entropy alloy film prepared by magnetron sputtering has practical application potential due to the compact structure, good combination with a matrix and high hardness. For example, the invention patent 201410082293.2 of Jianjian province has adopted magnetron sputtering to prepare two single-phase high-entropy alloy films, the five-element high-entropy alloy film of NiCrCoCuFe is of single-phase FCC structure, and the NiCrCoCuFeAl is_4.5The six-element high-entropy alloy film is of a single-phase BCC structure; the invention patent 201910429868.6 of Wangze et al adopts a magnetron sputtering method to prepare a CoCrFeMnNi high-entropy alloy film, and the XRD result shows that the film is of a single-phase structure; the invention patent 201810556405.1 of Song faith et al adopts magnetron sputtering to prepare TiNbHfZr quaternary refractory high-entropy alloy film, the structure of which is single-phase BCC structure and a small amount of HCP structure, and the strengthening mechanism is mainly solid solution strengthening because the HCP phase content is less. For a high-entropy alloy bulk phase material, a single-phase FCC high-entropy alloy has higher toughness but lower hardness; the single-phase BCC high-entropy alloy has higher hardness but insufficient toughness. Therefore, the method for synthesizing the FCC and BCC coexisting dual-phase high-entropy alloy has the advantages of high hardness and high toughness, and is an important way for realizing the toughness and toughness integration of the high-entropy alloy. However, due to the high entropy effect of the high-entropy alloy thin film and the rapid cooling process in the magnetron sputtering preparation process, elements in the thin film are difficult to separate by diffusion to obtain a two-phase structure. Y, P, Cai and the like adopt a two-step method to prepare a two-phase high-entropy alloy film, and firstly adoptThe CoCrCuFeNi/Al multilayer film is prepared by magnetron sputtering, and then annealing is carried out for 1 hour at 500 ℃, so that the FCC + BCC two-phase high-entropy alloy film is finally obtained, the hardness of the film can reach 10.4GPa, however, the two-step method has the defects of complex process and high cost, and the annealing step can increase the energy consumption. The invention patent CN202011487504.2 of Huangping et al prepares a biphase CrMnFeCoNi high-entropy alloy film of amorphous wrapped FCC nanocrystalline with the highest hardness of 9GPa through radio frequency magnetron sputtering, and the biphase structure is essentially uniform in chemical components and still insufficient in film hardness. The preparation of the two-phase high-entropy alloy film formed by element diffusion and precipitation by a magnetron sputtering one-step method in the prior art still faces a great challenge.

Disclosure of Invention

The invention aims to provide a preparation method of a CuNiTiNbCr nano dual-phase high-entropy alloy film, aiming at the problems of the existing method for synthesizing the dual-phase high-entropy alloy film with coexisting FCC and BCC.

From the aspect of enthalpy of mixing, when the enthalpy of mixing of one element with other elements in the film is more positive, the element is easy to generate segregation by diffusion, so the enthalpy of mixing is referred to from the aspect of composition design. The enthalpy of mixing Cu with elements such as Ni, Nb, Cr, Ti, Fe, Co, Mn, V, Al and the like is more positive and is obviously higher than the enthalpy of mixing other elements such as Ni, Nb, Cr, Ti and the like between every two elements. Therefore, the selection of the above elements is expected to realize the segregation of Cu. Based on the special component design, the BCC nano second phase is formed by utilizing diffusion segregation of Cu, so that the mechanical property of the film is improved.

The preparation method of the nano biphase high-entropy alloy film mainly comprises two steps of base material pretreatment and high-power pulse magnetron sputtering deposition. The method adopts a high-power pulse magnetron sputtering technology, takes spliced targets of five elements of metal Cu, metal A, metal B, metal C and metal D as target materials, and the purity of the spliced targets is more than 99 percent; and (3) applying negative bias to the substrate by taking high-purity Ar as working gas, applying target voltage to the spliced target, and depositing on the surface of the substrate to obtain the nano two-phase high-entropy alloy film, wherein the nano two-phase high-entropy alloy film comprises an FCC substrate phase and a copper-rich BCC nano phase. The metal A is Ni or Ti; the metal B is one of Ti, Fe and Cr; the metal C is one of Nb, Co and V; the metal D is one of Cr, Al and Mn; the four elements of the metal A, the metal B, the metal C and the metal D in the target material are four different elements.

The preparation method comprises the following steps:

(1) carrying out ultrasonic cleaning on the matrix; the substrate was placed in acetone and ultrasonically cleaned for 15 minutes, followed by 15 minutes in absolute ethanol and finally taken out and blown dry with nitrogen.

(2) Plasma glow discharge sputtering cleaning: loading the substrate treated in the step (1) into a high-power pulse magnetron sputtering cavity, and vacuumizing the cavity to 1 x 10^-3Pa～5×10^-3Pa, then introducing high-purity Ar with the purity of more than or equal to 99.9 percent into the cavity, adjusting the air pressure in the cavity to 3-4 Pa, applying negative bias of-1000 to-1500V to the substrate, generating Ar plasma near the substrate, wherein Ar in the plasma⁺And (3) bombarding the substrate under the negative bias of the substrate to perform bias reverse sputtering cleaning, wherein the cleaning time is 20-30 min.

(3) The method for depositing the nano biphase high-entropy alloy film can comprise the following two operation methods:

method one, before deposition, the chamber is vacuumized to 1 × 10^-3Pa～5×10^-3Pa, keeping the flow of Ar constant, wherein the flow of Ar is 40sccm, and maintaining the vacuum degree at 0.5-2.5 Pa by controlling the pumping speed of a vacuum pump; the average power of the five-element spliced target is 4-9W/cm²Applying bias voltage of 0-200V to the substrate, and depositing a nano two-phase high-entropy alloy film on the surface of the substrate; the lower layer of the film is a single FCC matrix phase, and the surface layer of the film is a two-phase composite structure of the FCC matrix phase and a copper-rich BCC nano phase.

Second, before deposition, the chamber is vacuumized to 1 × 10^-3Pa～5×10^-3Pa, keeping the Ar gas flow unchanged, wherein the Ar flow is 40sccm, maintaining the vacuum degree at 0.5-2.5 Pa by controlling the pumping speed of a vacuum pump, and starting a heating power supply to keep the temperature of the vacuum chamber at 200 ℃; the average power of the five-element spliced target is 4-9W/cm²Applying bias voltage of 0-200V to the substrate, and depositing a nano two-phase high-entropy alloy film on the surface of the substrate, wherein the film is integrally of a two-phase composite structure of an FCC substrate phase and a copper-rich BCC nano phase.

The difference between the two methods of this step is whether heating to 200 ℃ is carried out or not, and the structure of the resulting film is also different.

(4) After the film deposition is finished, cooling to below 100 ℃ in a vacuum environment, opening a cavity and discharging, and obtaining the nano two-phase high-entropy alloy film on the surface of the substrate.

Preferably, the nano dual-phase high-entropy alloy film can be one of a CuNiTiNbCr film, a CuNiFeCoAl film, a CuTiCrVAl film and a CuNiFeCoMn film.

The components of the prepared nano biphase high-entropy alloy film are as follows according to atomic percentage:

cu: 15-35% of A, 15-35% of B, 15-35% of C, 15-35% of D, and the sum of all atomic percentages is 100%.

Compared with the prior art, the invention has the advantages that:

the nano-biphase composite high-entropy alloy toughness integrated film is prepared by controlling the diffusion and precipitation of film elements in the film deposition process, and the prepared high-entropy alloy biphase composite film has high hardness, high toughness and excellent wear resistance. In the deposition process, the diffusion of Cu element in the film is regulated and controlled by controlling the deposition pressure, the target average power and the matrix bias of the quinary spliced target, so that the content of the copper-rich phase in the film is regulated and controlled.

In the deposition process, the diffusion of Cu element is controlled by controlling the ionization rate and the particle energy of sputtering particles, so that a copper-rich phase with proper grain size is precipitated, and finally a dual-phase structure of a copper-rich BCC precipitated phase and an FCC matrix phase is formed in the film. The high-entropy alloy has a high solid solution strengthening effect, the hardness of the film can be further improved by the precipitation of the hard BCC second phase, in addition, a large number of phase interfaces are introduced into the film by the precipitation of the BCC phase, the mechanical property of the film is further improved by an interface strengthening mechanism, and meanwhile, the excellent toughness of the film is still maintained by the matrix phase of the FCC structure. The nano biphase high-entropy alloy film has the characteristic of toughness integration and has the potential of application in high-bearing and high-abrasion environments. In addition, by utilizing the cumulative effect of the substrate temperature rise in the film deposition process, a dual-phase reinforced structure with the lower layer of the film being an FCC (fluid catalytic cracking) tough phase and the surface layer being an FCC + BCC (body-centered carbon) tough phase can be obtained, and the gradient structure with strong surface and tough inside can coordinate the stress matching of the film and a matrix, improve the film-substrate binding force and prolong the service life of the film.

The CuNiTiNbCr nano dual-phase high-entropy alloy film prepared by the preparation method of the invention has the toughness and toughness integrated characteristic. The hardness of the high-strength wear-resistant steel reaches 13GPa, the high-strength wear-resistant steel has excellent toughness, and the high-strength wear-resistant steel has a good protection effect on a base body which operates in a high-bearing and high-friction environment, such as metal or alloy mechanical motion base parts, such as pistons, gears, valves and the like, so that the comprehensive performance and the service life of the base body are effectively improved, the urgent need of the rapid development of the modern mechanical industry on the surface protection problem of parts is met, and the high-strength wear-resistant steel has good application value.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a XRD test result chart of a CuNiTiNbCr nano-dual-phase high-entropy alloy film with Si as a matrix in example 1 of the invention.

FIG. 2 is a transmission electron microscope test result chart of the CuNiTiNbCr nano-dual-phase high-entropy alloy film with Si as the matrix in example 1 of the invention.

FIG. 3 is an indentation pattern of a Vickers indenter of a CuNiTiNbCr nano-sized two-phase high-entropy alloy film based on 304 stainless steel under a force of 1kg in example 1 of the present invention.

FIG. 4 is an indentation pattern of a Vickers indenter of a CuNiTiNbCr nano-sized two-phase high-entropy alloy film based on 304 stainless steel under a force of 1kg in example 2 of the present invention.

FIG. 5 is an indentation pattern of a Vickers indenter of a CuNiTiNbCr nano-sized two-phase high-entropy alloy film based on 304 stainless steel under a force of 1kg in example 3 of the present invention.

FIG. 6 is a XRD test result of the CuNiTiNbCr high-entropy alloy film based on Si in comparative example 1 of the invention.

FIG. 7 is an indentation pattern of a Vickers indenter of a CuNiTiNbCr high-entropy alloy film based on 304 stainless steel in comparative example 1 of the invention under a force of 1 kg.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Example 1

The CuNiTiNbCr nano double-phase high-entropy alloy film is prepared on a 304 stainless steel and Si substrate, and the preparation method specifically comprises the following steps:

(1) pre-plating treatment

The substrate was placed in acetone and ultrasonically cleaned for 15 minutes, followed by 15 minutes in absolute ethanol and finally taken out and blown dry with nitrogen.

(2) Plasma glow discharge sputter cleaning

Loading the substrate treated in the step (1) into a high-power pulse magnetron sputtering cavity, wherein the cavity is not heated, and the intrinsic vacuum is pre-pumped to 2.0 multiplied by 10^-3Pa; then, introducing Ar gas with purity of 99.999% or more into the cavity, wherein Ar gas pressure is 3.0Pa, applying negative bias of-1500V on the substrate, generating Ar plasma near the substrate, and Ar⁺The substrate was continuously bombarded under negative bias for 20 minutes.

(3) Deposited CuNiTiNbCr nano biphase high-entropy alloy film

Firstly, the chamber is evacuated to 1 × 10^-3Pa～5×10^-3Pa, then introducing Ar gas, keeping the flow of the Ar gas unchanged, wherein the flow is 40sccm, and maintaining the vacuum degree in the cavity at 0.5 Pa; the average power of the five-element spliced target is 4W/cm²Applying 0V bias voltage to the substrate, and depositing the CuNiTiNbCr nano two-phase high-entropy alloy film on the surface of the substrate for 40 min.

(4) After the film deposition is finished, cooling to below 100 ℃ in a vacuum environment, then discharging to atmospheric pressure, opening a cavity and discharging, and obtaining the CuNiTiNbCr nano two-phase high-entropy alloy film on the surface of the substrate.

The CuNiTiNbCr nano-biphase high-entropy alloy film prepared by the method is subjected to the following structure and performance tests:

(1) XRD and TEM are adopted to characterize the phase structure of the film. As shown in FIG. 1, the XRD pattern of the film has two sets of diffraction patterns of FCC and BCC, indicating that the film has a two-phase structure of FCC and BCC. In fig. 2, the TEM topography results of fig. 2(b) and (d) show that granular nanocrystals are precipitated in the thin film near the upper surface; the electron diffraction patterns (fig. 2(c), (e), (f)) show that the precipitated nanocrystals were BCC structure, while the matrix phase was FCC structure, consistent with XRD results. FIGS. 2(g), (h), (i) show that the side of the film close to the substrate is of FCC single-phase structure. Therefore, the film as a whole has a gradient structure with a single FCC phase on the lower side and a two-phase FCC + BCC on the upper side.

(2) And pressing the substrate into a test platform at 200 nm of MTS-Nano G to measure the hardness and the elastic modulus of the film on the surface of the substrate by a continuous stiffness method. The determination method comprises the following steps: selecting 6 different areas on the surface of the film, pressing the film into a fixed depth of 1000nm by a Berkovich diamond pressure head, then unloading the film to obtain a pressing-unloading curve, calculating to obtain the hardness and the elastic modulus of the film, and then taking an average value. As shown in Table 2, the hardness of the CuNiTiNbCr nano-sized two-phase high-entropy alloy thin film was 10.1 GPa.

(3) The toughness of the film is tested by adopting a Vickers pressure head pressing-in method, and the maximum loading force is 1 kg. As a result, as shown in FIG. 3, no cracks were observed, indicating that the film had excellent toughness.

(4) And evaluating the frictional wear performance of the surface film of the substrate in the atmospheric environment by adopting a UMT-3 multifunctional frictional wear testing machine. The specific method comprises the following steps: a coated stainless steel sample and a friction matching pair are adopted to slide in a mutual reciprocating manner, the sliding frequency is 2Hz, the load is 1N, the environmental temperature is (15 +/-3) DEG C, the relative humidity is (55 +/-5)%, and phi is 6mm of GCr15 balls serving as the friction matching pair. The average friction coefficient and the wear rate are shown in Table 2, the average friction coefficient is 0.49, and the wear rate is 8.2X 10^- ⁶mm³/N·m。

Example 2

In this embodiment, the substrate is the same as the substrate in embodiment 1, and the CuNiTiNbCr nano-two-phase composite film is prepared on the surface of the substrate, the preparation method specifically includes:

(1) same as in step (1) in example 1;

(2) same as step (2) in example 1;

(3) deposited CuNiTiNbCr nano biphase high-entropy alloy film

Firstly, the chamber is evacuated to 1 × 10^-3Pa～5×10^-3Pa, then introducing Ar gas, keeping the flow of the Ar gas unchanged, controlling the flow of 40sccm, and maintaining the vacuum degree at 1.0Pa by controlling the pumping speed of a vacuum pump; the average power of the quinary spliced target is 8W/cm²Applying 0V bias voltage to the substrate, and depositing the CuNiTiNbCr nano two-phase high-entropy alloy film on the surface of the substrate for 40 min.

(4) Same as in step (4) in example 1.

(1) XRD and TEM are adopted to characterize the phase structure of the film. The test results show that the film as a whole has a gradient structure with a single FCC phase on the lower side and a two-phase FCC + BCC on the upper side.

(2) The hardness test was the same as in test procedure (1) in example 1. As shown in Table 1, the hardness of the CuNiTiNbCr nano-sized two-phase high-entropy alloy thin film was 10.5 GPa.

(3) The film toughness test was the same as in test step (2) of example 1, and as a result, as shown in FIG. 4, slight cracks occurred at the edge of the indentation.

(4) The frictional wear test was the same as the test procedure (2) in example 1. The average friction coefficient and the wear rate are shown in Table 1, the average friction coefficient is 0.46, and the wear rate is 7.6X 10^-6mm³/N·m。

Example 3

(1) same as in step (1) in example 1;

(2) same as step (2) in example 1;

(3) deposited CuNiTiNbCr nano biphase high-entropy alloy film

Firstly, the chamber is evacuated to 1 × 10^-3Pa～5×10^-3Pa, then introducing Ar gas, keeping the flow of the Ar gas unchanged, controlling the flow of 40sccm, and maintaining the vacuum degree at 2.5Pa by controlling the pumping speed of a vacuum pump; the average power of the five-element spliced target is 6W/cm²Applying a bias voltage of-150V to the substrate, and depositing the CuNiTiNbCr nano two-phase high-entropy alloy film on the surface of the substrate for 40 min.

(4) Same as in step (4) in example 1.

(2) The hardness test was the same as in test procedure (1) in example 1. As shown in Table 1, the hardness of the CuNiTiNbCr nano-sized two-phase high-entropy alloy thin film was 12.0 GPa.

(3) The film toughness test was the same as the test procedure (2) in example 1, and the results are shown in FIG. 5, in which the indentation edge was more significantly cracked, indicating a decrease in toughness.

(4) The frictional wear test was the same as the test procedure (2) in example 1. The average friction coefficient and the wear rate are shown in Table 1, the average friction coefficient is 0.41, and the wear rate is 4.5X 10^-6mm³/N·m。

Examples 4 to 11, the preparation method was the same as example 1, and the specific values of the process parameters of each example are shown in table 1; the phase structure, hardness, friction coefficient and wear rate are shown in Table 2.

Example 12

The preparation method was carried out in the same manner as in example 1, and the specific values of the process parameters were also the same as in example 1 (as shown in Table 1), except that heating was carried out in step (3). The step (3) is specifically as follows: firstly, the chamber is vacuumized to 1 x 10^-3Pa～5×10^- ³Pa, then introducing Ar gas, and keeping the Ar gasThe flow is unchanged, the Ar flow is 40sccm, the vacuum degree is maintained at 0.5Pa by controlling the pumping speed of a vacuum pump, and a heating power supply is started to keep the temperature of the vacuum chamber at 200 ℃; the average power of the five-element spliced target is 4W/cm²Applying bias voltage of 0V to the substrate, and depositing the CuNiTiNbCr nano two-phase high-entropy alloy film on the surface of the substrate for 40 min.

XRD and TEM are adopted to characterize the phase structure of the film. The test result shows that the film is integrally of a two-phase composite structure of an FCC matrix phase and a copper-rich BCC nano phase. Other performance test results are shown in table 2.

Example 13

Splicing targets of five elements of Cu, Ni, Fe, Co and Al are adopted as targets, the operation method of the embodiment 1 is adopted, and specific values of various process parameters are shown in Table 1. And preparing the CuNiFeCoAl nano two-phase high-entropy alloy film.

XRD and TEM are adopted to characterize the phase structure of the film. The test results show that the film as a whole has a gradient structure with a single FCC phase on the lower side and a two-phase FCC + BCC on the upper side. The results of the film structure and performance testing are shown in table 2.

Example 14

Splicing targets of five elements of Cu, Ti, Cr, V and Al are adopted as targets, the operation method of the embodiment 1 is adopted, and specific values of various process parameters are shown in Table 1. And preparing the CuTiCrVAl nano two-phase high-entropy alloy film.

Example 15

Splicing targets of five elements of Cu, Ni, Fe, Co and Mn are used as targets, the operation method of the embodiment 1 is adopted, and specific values of various process parameters are shown in Table 1. And preparing the CuNiFeCoMn nano biphase high-entropy alloy film.

Comparative example 1

In this embodiment, the substrate is completely the same as the substrate in embodiment 1, and the CuNiTiNbCr film is prepared on the surface of the substrate, and the preparation method specifically comprises the following steps:

(1) same as in step (1) in example 1;

(2) same as step (2) in example 1;

(3) deposited CuNiTiNbCr nano biphase high-entropy alloy film

Firstly, the chamber is evacuated to 1 × 10^-3Pa～5×10^-3Pa, then introducing Ar gas, keeping the flow of the Ar gas constant, controlling the flow of 40sccm, and maintaining the vacuum degree at 0.4Pa by controlling the pumping speed of a vacuum pump; the average power of the quinary spliced target is 3W/cm²Applying a bias voltage of-250V to the substrate, and depositing the CuNiTiNbCr high-entropy alloy film on the surface of the substrate for 40 min.

(4) Same as in step (4) in example 1.

The CuNiTiNbCr high-entropy alloy film prepared by the method is subjected to the following structure and performance tests:

(1) and (3) characterizing the phase structure of the film by XRD. The test results (see fig. 6) show that the film is of FCC single-phase structure.

(2) The hardness test was the same as in test procedure (1) in example 1. As shown in Table 1, the hardness of the CuNiTiNbCr high-entropy alloy thin film was 7.0 GPa.

(3) The film toughness test was the same as the test procedure (2) in example 1, and as a result, as shown in fig. 7, significant peeling occurred at the edge of the indentation due to excessive stress in the film caused by too high deposition bias.

(4) The frictional wear test was the same as the test procedure (2) in example 1. The average friction coefficient and the wear rate are shown in Table 1, the average friction coefficient is 0.65, and the wear rate is 14.7X 10^-6mm³/N·m。

Specific values of the respective process parameters of comparative examples 2 to 4 are shown in Table 1; the phase structure, hardness, friction coefficient and wear rate are shown in Table 2.

Table 1, examples 4 to 15 and comparative examples 1 to 4 show the respective process parameters

TABLE 2 phase structure, hardness, friction coefficient and wear rate of the films in each of examples and comparative examples

In conclusion, in the preparation method, the two-phase nano-composite high-entropy alloy film is prepared by controlling the diffusion and precipitation of film elements in the film deposition process, and the high-entropy alloy two-phase composite film prepared by the method has high hardness, high toughness and excellent wear resistance.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for preparing a nano biphase high-entropy alloy film is characterized in that a high-power pulse magnetron sputtering technology is adopted, and a splicing target of five elements of metal Cu, metal A, metal B, metal C and metal D is adoptedTaking high-purity Ar as working gas, applying negative bias to a substrate, applying target voltage to a splicing target, and depositing on the surface of the substrate to obtain a nano two-phase high-entropy alloy film, wherein the nano two-phase high-entropy alloy film comprises an FCC substrate phase and a copper-rich BCC nano phase; controlling the vacuum degree of the cavity to be 0.5-2.5 Pa and the average power of the splicing target to be 4-9W/cm in the deposition process²The bias voltage of the substrate is 0 to-200V;

the metal A is Ni or Ti; the metal B is one of Ti, Fe and Cr; the metal C is one of Nb, Co and V; the metal D is one of Cr, Al and Mn; the four elements of the metal A, the metal B, the metal C and the metal D in the target material are four different elements.

2. The method for preparing the nano biphase high entropy alloy film as claimed in claim 1, characterized by comprising the following steps:

(1) carrying out ultrasonic cleaning on the matrix;

(2) plasma glow discharge sputtering cleaning: loading the substrate treated in the step (1) into a high-power pulse magnetron sputtering cavity, introducing high-purity Ar into the cavity, adjusting the air pressure in the cavity to 3-4 Pa, applying negative bias of-1000 to-1500V to the substrate, and bombarding the substrate by Ar plasma generated near the substrate under the negative bias of the substrate to perform bias reverse sputtering cleaning;

(3) depositing a nano biphase high-entropy alloy film;

3. The method for preparing a nano biphase high entropy alloy thin film as claimed in claim 2, wherein in the step (2), the chamber background is vacuumized to 1 x 10 before cleaning^-3Pa～5×10^-3Pa; ar pressure is 0.5-3 Pa, and cleaning time is 20-30 min.

4. The method for preparing the nano biphase high entropy alloy thin film as claimed in claim 2, wherein the step (3) is specifically: evacuating the chamber before depositionTo 1X 10^-3Pa～5×10^-3Pa, keeping the flow of Ar gas unchanged, and maintaining the vacuum degree at 0.5-2.5 Pa; the average power of the five-element spliced target is 4-9W/cm²Applying bias voltage of 0-200V to the substrate, and depositing a nano two-phase high-entropy alloy film on the surface of the substrate; the lower layer of the film is a single FCC matrix phase, and the surface layer of the film is a two-phase composite structure of the FCC matrix phase and a copper-rich BCC nano phase.

5. The method for preparing the nano biphase high entropy alloy thin film as claimed in claim 2, wherein the step (3) is specifically: before deposition, the chamber is evacuated to 1 × 10^-3Pa～5×10^-3Pa, keeping the flow of Ar gas unchanged, maintaining the vacuum degree at 0.5-2.5 Pa, and starting a heating power supply to keep the temperature of the vacuum chamber at 200 ℃; the average power of the five-element spliced target is 4-9W/cm²Applying bias voltage of 0-200V to the substrate, and depositing a nano two-phase high-entropy alloy film on the surface of the substrate, wherein the film is integrally of a two-phase composite structure of an FCC substrate phase and a copper-rich BCC nano phase.

6. The method for preparing a nano biphase high entropy alloy thin film according to claim 5, wherein the purity of the five targets of the splicing target is more than 99%.

7. The method for preparing a nano biphase high entropy alloy thin film as claimed in claim 2, wherein the cleaning process in the step (1) is as follows: the substrate was placed in acetone and ultrasonically cleaned for 15 minutes, followed by 15 minutes in absolute ethanol and finally taken out and blown dry with nitrogen.

8. A nano-sized two-phase high-entropy alloy thin film, which is produced by the production method according to any one of claims 1 to 7.

9. The nano-sized biphase high entropy alloy thin film as claimed in claim 8, wherein the composition of the thin film is as follows in atomic percent:

10. The nano-bi-phase high-entropy alloy thin film as claimed in claim 9, wherein the nano-bi-phase high-entropy alloy thin film is one of a CuNiTiNbCr thin film, a cunifeCoal thin film, a CuTiCrVAl thin film, and a CuNiFeCoMn thin film.