CN116516228A - A superhard wear-resistant refractory high-entropy alloy film and its preparation method - Google Patents

Abstract

The invention belongs to the technical field of wear-resistant alloy materials, and relates to a superhard wear-resistant refractory high-entropy alloy film and a preparation method thereof. The super-hard wear-resistant refractory high-entropy alloy thin film has the characteristics of ultra-fine nanocrystals, extraordinary hardness and wear resistance, and the like. The preparation method includes the following steps: preparing a NbMoWTa refractory high-entropy alloy target; the sputtering target is formed by ball milling and mixing Nb, Mo, W, and Ta metal powders, and then plasma sintering at high temperature ; Using the magnetron sputtering method to sputter the obtained refractory high-entropy alloy target on the silicon substrate to form a film to obtain a superhard wear-resistant refractory high-entropy alloy film. The preparation process of the invention is simple, stable and controllable; the obtained product has fine and uniform crystal grains, excellent mechanical properties and wear resistance. This provides the necessary conditions for the realization of refractory high-entropy alloys in extreme engineering applications.

Description

A superhard wear-resistant refractory high-entropy alloy film and its preparation method

technical field

The invention relates to the technical field of wear-resistant alloy materials, in particular to a superhard wear-resistant refractory high-entropy alloy film and a preparation method thereof.

Background technique

High-entropy alloys are composed of four or more alloying elements mixed in an equimolar ratio or nearly equimolar ratio, and its multi-components will lead to a high mixing entropy, showing a high-entropy effect in thermodynamics, often A single-phase solid solution structure is formed instead of a brittle intermetallic compound. Therefore, compared with traditional alloys, high-entropy alloys exhibit excellent mechanical and physical and chemical properties such as high strength, radiation resistance, and corrosion resistance. Refractory high-entropy alloys are a class of high-entropy alloys that are mixed with four or more refractory metal elements (such as Nb, Mo, W, Ta, V, Zr, Hf) in equal or nearly equal atomic ratios. Entropy alloys, because the components have high melting points, etc., compared with traditional nickel-based and cobalt-based superalloys, refractory high-entropy alloys have higher tempering resistance and high-temperature softening resistance, and are expected to be used in aviation and aerospace. , Nuclear energy and other high temperature and harsh working conditions.

However, due to the high melting point of refractory high-entropy alloys, it is difficult to prepare refractory high-entropy alloys with uniform structure and single-phase structure by traditional arc melting and powder metallurgy methods, which restricts the development of refractory high-entropy alloys; Secondly, the cost of bulk refractory high-entropy alloys is too high to push them into large-scale applications. Therefore, coating refractory high-entropy alloy thin films on the surface of existing parts may have greater economic benefits.

At present, the preparation methods of thin films mainly include magnetron sputtering, laser cladding, and plasma spraying. Among them, the magnetron sputtering technology has the advantages of fast deposition speed, can be deposited on various substrates, and the obtained thin film is high in purity, uniform and dense, and can accurately control the thickness. It is an ideal technology to push it to practical production applications; On the other hand, this technology only involves the physical sputtering process of the target without heating and melting it, so it is very suitable for the preparation of refractory high-entropy alloy thin films.

In addition, due to the very different element properties among the multi-components of refractory high-entropy alloys, coating materials with special structures are expected to be prepared through reasonable regulation of the magnetron sputtering process, so as to obtain extraordinary mechanical and friction properties.

Contents of the invention

The purpose of the present invention is to provide a superhard wear-resistant refractory high-entropy alloy thin film and a preparation method thereof, so as to realize the technical effects proposed in the background art above.

In order to achieve the above object, the invention provides the following technical solution: a superhard wear-resistant refractory high-entropy alloy thin film, including the following alloy components with equal atomic percentages: Nb, Mo, W, Ta.

Preferably, the superhard wear-resistant refractory high-entropy alloy film has a single-phase BCC solid solution structure, the grain size is not higher than 25 nm, and the film thickness is 3.0-3.5 μm.

Preferably, the original structure of the superhard wear-resistant refractory high-entropy alloy thin film exhibits an amplitude-modulated layered decomposition substructure with a periodicity of 5-10 nm.

Preferably, the nano-indentation hardness of the superhard wear-resistant refractory high-entropy alloy film is 20-25 GPa, and the wear rate is 1.0×10 ^-5 -1.4×10 ^-5 mm ³ /(N·m).

A method for preparing a superhard wear-resistant refractory high-entropy alloy film, specifically comprising the following steps:

Step 1: Preparation of sputtering target: Mix metal powders of elemental elements Nb, Mo, W, and Ta in equimolar proportions using high-energy ball milling for 24-30 hours, and then use plasma sintering technology at 1500-1700°C to prepare NbMoWTa refractory high-entropy alloy target with equiatomic ratio;

Step 2: Thin film deposition: The alloy target obtained in step 1 is sputtered on the silicon substrate to form a film by magnetron sputtering technology, the sputtering power is 100~120W, the bias voltage is -80~-100V, and super Hard and wear-resistant refractory high-entropy alloy thin films.

Preferably, the silicon substrate is a single-sided polished single-crystal silicon substrate cleaned with acetone and absolute ethanol and dried.

Preferably, the deposition rate in the magnetron sputtering technique is 0.19-0.22 nm/s.

Preferably, the magnetron sputtering technology uses DC power sputtering.

Preferably, the magnetron sputtering technology uses Ar with a purity as high as 99.99% as the ionized gas.

Compared with the prior art, the beneficial effects of the invention are:

1. The ultra-hard wear-resistant refractory high-entropy alloy thin film and its preparation method, the preparation method of the ultra-hard wear-resistant refractory high-entropy alloy thin film provided has the advantages of fast deposition speed, easy process control, precise and controllable film thickness, and economic benefits Advanced advantages.

2. The ultra-hard wear-resistant refractory high-entropy alloy film and its preparation method. The prepared super-hard wear-resistant refractory high-entropy alloy film has a smooth surface, a dense structure, a grain size of no higher than 25nm, and ultrafine nanocrystalline The film thickness is 3.0-3.5μm, and the film-base bonding force is good, which can directly meet the service requirements of key wear-resistant parts; in addition, through process regulation, specific working air pressure, power supply, deposition rate, substrate rotation, Substrate bias, ionized gas protection after deposition, etc., segregate the W and Ta elements in the refractory alloy elements, resulting in the formation of an amplitude-modulated layered decomposition substructure with a periodicity of 5-10nm, in order to achieve refractory high entropy Alloy superhard and super wear resistance provide structural basis.

3. The super-hard wear-resistant refractory high-entropy alloy film and its preparation method, the nano-indentation hardness of the prepared super-hard wear-resistant refractory high-entropy alloy film is 20-25GPa, and the wear rate is 1.0× ^10-5 ～ 1.4×10 ^-5 mm ³ /(N m), in which the multi-principal solid solution strengthening, ultrafine nanocrystalline strengthening effect, unique amplitude modulation decomposition layered structure strengthening effect and the superposition effect of columnar grain boundary strengthening lead to its Ultra-high hardness; in addition, a higher substrate bias will cause the film to be bombarded by more ions during the forming process, which will increase the internal stress of the film and lead to high hardness of the film. The films prepared by the invention are all higher than the refractory high-entropy alloy films of the same system studied at the present stage, and have broad application prospects.

Description of drawings

Fig. 1 is the XRD spectrum of the NbMoWTa refractory high-entropy alloy film prepared by the present invention;

Fig. 2 is the cross-sectional image of the NbMoWTa refractory high-entropy alloy film prepared by the present invention; (a) scanning electron microscope; (b) transmission electron microscope;

Fig. 3 is the substructural element distribution image of the NbMoWTa refractory high-entropy alloy film prepared by the present invention;

Fig. 4 is a comparison diagram of the hardness and wear resistance of the NbMoWTa refractory high-entropy alloy film prepared by the present invention and the refractory metal single substance and refractory high-entropy alloy studied at the present stage: (a) hardness comparison; (b) wear rate Compared.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1:

A method for preparing a superhard wear-resistant refractory high-entropy alloy film, comprising the following steps:

1) The metal powders of elemental elements Nb, Mo, W, and Ta were mixed in equimolar proportions using high-energy ball milling for 24 hours, and then NbMoWTa refractory high-entropy alloy targets with equimolar ratios were prepared by plasma sintering technology at 1700°C material;

2) The silicon substrate was ultrasonically cleaned in acetone and absolute ethanol for 20 minutes, and then dried with a hair dryer to ensure the removal of oil and water on the surface of the silicon substrate;

3) Put the silicon substrate and the alloy target into the substrate stage and the sputtering target stage in the magnetron sputtering furnace respectively, adjust the sputtering angle to 30-45° and then fix it to ensure that the sputtered atoms can hit the silicon wafer In the center, start the mechanical pump and the molecular pump in turn, and vacuum the sputtering furnace to 4×10 ^-5 Pa to prepare for coating;

4) Introduce high-purity Ar gas to ensure that the pressure in the furnace is 0.2Pa to ensure normal glow discharge and good coating quality. Connect the target platform to the power supply of the equipment, set the sputtering power to 100W, and the bias voltage to - 80V, start the power supply and start pre-sputtering for 10 minutes;

5) Turn on the target baffle and the substrate table to rotate, and start sputtering. After 4 hours of sputtering, turn off the target baffle, power supply, and bias voltage in sequence, and keep feeding Ar gas, so that the finished film and the silicon substrate are in the Ar atmosphere. Cool in medium for 1.5 hours to avoid cracking due to excessive surface stress of the film, then stop the ventilation, and take it out after the vacuum is turned off to obtain a superhard wear-resistant refractory high-entropy alloy film deposited on a silicon substrate.

Example 2:

A method for preparing a superhard wear-resistant refractory high-entropy alloy film, comprising the following steps:

1) The metal powders of elemental elements Nb, Mo, W, and Ta were mixed in equimolar proportions using high-energy ball milling for 24 hours, and then NbMoWTa refractory high-entropy alloy targets with equimolar ratios were prepared by plasma sintering technology at 1700°C material;

2) The silicon substrate was ultrasonically cleaned in acetone and absolute ethanol for 20 minutes, and then dried with a hair dryer to ensure the removal of oil and water on the surface of the silicon substrate;

3) Put the silicon substrate and the alloy target into the substrate stage and the sputtering target stage in the magnetron sputtering furnace respectively, adjust the sputtering angle to 30-45° and then fix it to ensure that the sputtered atoms can hit the silicon wafer In the center, start the mechanical pump and the molecular pump in turn, and vacuum the sputtering furnace to 4×10 ^-5 Pa to prepare for coating;

4) Introduce high-purity Ar gas to ensure that the pressure in the furnace is 0.3Pa to ensure normal glow discharge and good coating quality. Connect the target platform to the power supply of the equipment, set the sputtering power to 110W, and the bias voltage to - 90V, start the power supply and start pre-sputtering for 10 minutes;

5) Turn on the target baffle and the substrate table to rotate, and start sputtering. After 4 hours of sputtering, turn off the target baffle, power supply, and bias voltage in sequence, and keep feeding Ar gas, so that the finished film and the silicon substrate are in the Ar atmosphere. Cool in medium for 1.5 hours to avoid cracking due to excessive surface stress of the film, then stop the ventilation, and take it out after the vacuum is turned off to obtain a superhard wear-resistant refractory high-entropy alloy film deposited on a silicon substrate.

Example 3:

A method for preparing a superhard wear-resistant refractory high-entropy alloy film, comprising the following steps:

1) The metal powders of elemental elements Nb, Mo, W, and Ta were mixed in equimolar proportions using high-energy ball milling for 24 hours, and then NbMoWTa refractory high-entropy alloy targets with equimolar ratios were prepared by plasma sintering technology at 1700°C material;

2) The silicon substrate was ultrasonically cleaned in acetone and absolute ethanol for 20 minutes, and then dried with a hair dryer to ensure the removal of oil and water on the surface of the silicon substrate;

3) Put the silicon substrate and the alloy target into the substrate stage and the sputtering target stage in the magnetron sputtering furnace respectively, adjust the sputtering angle to 30-45° and then fix it to ensure that the sputtered atoms can hit the silicon wafer In the center, start the mechanical pump and the molecular pump in turn, and vacuum the sputtering furnace to 4×10 ^-5 Pa to prepare for coating;

4) Introduce high-purity Ar gas to ensure that the pressure in the furnace is 0.2Pa to ensure normal glow discharge and good coating quality. Connect the target platform to the equipment power supply, set the sputtering power to 120W, and the bias voltage to - 100V, start the power supply and start pre-sputtering for 10 minutes;

5) Turn on the target baffle and the substrate table to rotate, and start sputtering. After 4 hours of sputtering, turn off the target baffle, power supply, and bias voltage in sequence, and keep feeding Ar gas, so that the finished film and the silicon substrate are in the Ar atmosphere. Cool in medium for 1.5 hours to avoid cracking due to excessive surface stress of the film, then stop the ventilation, and take it out after the vacuum is turned off to obtain a superhard wear-resistant refractory high-entropy alloy film deposited on a silicon substrate.

Since the performances of the superhard wear-resistant refractory high-entropy alloy thin films prepared in Examples 1-3 are basically the same, the effects of the superhard wear-resistant refractory high-entropy alloy thin films prepared in Example 1 are taken as an example below.

Fig. 1 is the XRD spectrum of the NbMoWTa refractory high-entropy alloy thin film prepared by the present invention, it can be seen that the thin film shows a single body-centered cubic solid solution structure, and has a preferred orientation of (110) crystal plane, and the diffraction peak intensity is relatively weak It is due to the fine grains inside it.

Fig. 2 is the cross-sectional scanning electron microscope and the transmission electron microscope image of the NbMoWTa refractory high-entropy alloy thin film prepared by the present invention, it can be seen that the crystal grains grow in a columnar shape perpendicular to the silicon substrate; through a higher magnification transmission electron microscope can It can be seen that the crystal grain size is extremely small, and the average size does not exceed 25 nm.

Fig. 3 is the substructure element distribution image of the NbMoWTa refractory high-entropy alloy prepared by the present invention. It can be seen that the distribution of W and Ta elements is not uniform, and it shows an amplitude-modulated decomposition substructure with a periodicity of 5-10 nm. The amplitude-modulated decomposition of ultrafine nanocrystals and alloying elements provides the structural basis for the excellent mechanical and wear resistance properties of the film.

Figure 4 is a comparison chart of the hardness and wear resistance of the NbMoWTa refractory high-entropy alloy film prepared by the present invention and the current research on the refractory metal single substance and refractory high-entropy alloy. It can be seen that the NbMoWTa refractory prepared by the present invention The hardness of the high-entropy alloy film exceeds 20GPa, which is better than that of the NbMoWTa series refractory high-entropy alloy and refractory metal element reported in the current literature 1-4, showing superhard characteristics; its wear resistance is much better than that of TiZrHfNb series, TiZrHfNbTa series and bulk NbMoWTa series refractory high-entropy alloys have wear rates ranging from 1.0×10 ^-5 to 1.4×10 ^-5 mm ³ /(N·m), showing super wear resistance.

The multi-principal solid solution strengthening, ultrafine nanocrystal strengthening effect, unique amplitude modulation decomposition substructure strengthening effect, and the superimposed effect of columnar grain boundary strengthening lead to the ultra-high hardness of the film; in addition, a higher substrate bias will lead to the thin film During the forming process, more ion bombardment increases the internal stress of the film, which is one of the reasons for the high hardness and wear resistance of the film.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (9)

1. A superhard wear-resistant refractory high-entropy alloy thin film is characterized in that: it includes the following alloy components in equal atomic percentages: Nb, Mo, W, Ta. 2. A kind of superhard wear-resistant refractory high-entropy alloy film as claimed in claim 1, characterized in that: said superhard wear-resistant refractory high-entropy alloy film has a single-phase BCC solid solution structure, and the grain size is not high At 25nm, the film thickness is 3.0-3.5μm. 3. A kind of superhard wear-resistant refractory high-entropy alloy film as claimed in claim 1, characterized in that: the original structure of the superhard wear-resistant refractory high-entropy alloy film shows periodicity of 5-10nm AM layered decomposition substructure. 4. A kind of superhard wear-resistant refractory high-entropy alloy film as claimed in claim 1, characterized in that: the nano-indentation hardness of the superhard wear-resistant refractory high-entropy alloy film is 20-25GPa, and the wear rate 1.0×10 ^-5 ~ 1.4×10 ^-5 mm ³ /(N·m). 5. A method for preparing a superhard wear-resistant refractory high-entropy alloy thin film, characterized in that it specifically comprises the following steps: Step 1: Preparation of sputtering target: Mix metal powders of elemental elements Nb, Mo, W, and Ta in equimolar proportions using high-energy ball milling for 24-30 hours, and then use plasma sintering technology at 1500-1700°C to prepare NbMoWTa refractory high-entropy alloy target with equiatomic ratio; Step 2: Thin film deposition: The alloy target obtained in step 1 is sputtered on the silicon substrate to form a film by magnetron sputtering technology, the sputtering power is 100~120W, the bias voltage is -80~-100V, and super Hard and wear-resistant refractory high-entropy alloy thin films. 6. The preparation method of a kind of superhard wear-resistant refractory high-entropy alloy thin film as claimed in claim 5, it is characterized in that: described silicon substrate adopts the one-sided polishing single-sided polishing surface after cleaning with acetone, absolute ethanol and drying. crystalline silicon substrate. 7 . The method for preparing a superhard wear-resistant refractory high-entropy alloy thin film according to claim 5 , wherein the deposition rate in the magnetron sputtering technique is 0.19-0.22 nm/s. 8. The method for preparing a superhard wear-resistant refractory high-entropy alloy thin film as claimed in claim 5, characterized in that: said magnetron sputtering technology adopts DC power sputtering. 9. The method for preparing a superhard wear-resistant refractory high-entropy alloy thin film as claimed in claim 5, characterized in that: the magnetron sputtering technology uses Ar with a purity as high as 99.99% as the ionized gas.