阅读说明：本技术 一种定量控制元素含量梯度变化的高熵合金薄膜及制备方法 (High-entropy alloy film capable of quantitatively controlling element content gradient change and preparation method thereof ) 是由 黄平 杨玥玥 王飞 于 2021-08-27 设计创作，主要内容包括：本发明公开了一种定量控制元素含量梯度变化的高熵合金薄膜及制备方法,该方法采用磁控溅射同时控制直流电源和射频电源进行溅射,进而控制所需锰元素的溅射沉积速率达到含量梯度连续变化的高熵合金薄膜。该薄膜按照原子百分比为：Cr：20-24％、Mn：20-42％、Fe：16-22％、Co：13-19％、Ni：10-13％,其中锰元素含量呈现了大幅连续梯度变化,所有组分的原子百分比之和为100％。该方法得到沿高熵合金薄膜厚度方向Mn元素从20at％到42at％连续梯度变化的样品。本发明可有效预测此含量控制对高熵合金的影响,寻找最优组分,符合高通量实验的设计目标。(The invention discloses a high-entropy alloy film with quantitative control of element content gradient change and a preparation method thereof. The film comprises the following components in atomic percentage: cr: 20-24%, Mn: 20-42%, Fe: 16-22%, Co: 13-19%, Ni: 10-13%, wherein the content of manganese element presents a large continuous gradient change, and the sum of atomic percentages of all components is 100%. The method obtains a sample with Mn element continuously changing in a gradient manner from 20 at% to 42 at% along the thickness direction of the high-entropy alloy film. The method can effectively predict the influence of the content control on the high-entropy alloy, search the optimal component and meet the design target of a high-throughput experiment.)

1. A high-entropy alloy film capable of quantitatively controlling element content gradient change is characterized in that: the paint comprises the following components in atomic percentage: cr: 20-24%, Mn: 20-42%, Fe: 16-22%, Co: 13-19%, Ni: 10-13%, wherein the content of manganese element presents a large continuous gradient change, and the sum of atomic percentages of all components is 100%.

2. A preparation method of a high-entropy alloy film with quantitative control of element content gradient change is characterized by comprising the following steps:

1) fixing a clean substrate and a bottom support, and placing the substrate and the bottom support on a suspended substrate table of ultrahigh vacuum magnetron sputtering equipment;

2) fixing the required high-entropy alloy target material and pure manganese target material on corresponding radio frequency and direct current power supplies;

3) high-purity argon is used as a main ionized gas for glow discharge, two targets are effectively sputtered and deposited on a substrate;

4) in the deposition process, firstly turning on a direct-current power supply to normally start, and then turning on a radio-frequency power supply to start;

5) controlling the power of the two power supplies to carry out multiple sputtering deposition, wherein the time duration of single sputtering is 30-60 min, and the intermittent time duration is 10-20 min.

3. The method of claim 2, wherein: the high-entropy alloy target material element is CrMnFeCoNi with nearly equal atomic ratio, and the purity of the high-entropy alloy target material and the purity of the pure manganese metal target material are both 99.9-99.99 wt%.

4. The method of claim 2, wherein: the substrate is clean single crystal silicon (100), (111).

5. The method of claim 2, wherein: high-purity argon with the purity of more than or equal to 99.999 percent is adopted.

6. The method of claim 2, wherein: the power of the RF power source is fixed at 110W to 130W, and the power of the DC power source is reduced from 30W to 0W at a rate of 6-10W at a time.

7. The method of claim 2, wherein: the number of times of sputtering is 4-7.

Technical Field

The invention belongs to the field of alloy materials, and particularly relates to a preparation method for quantitatively controlling the gradient change of element content along the thickness direction in a high-entropy alloy film sample.

Background

Since 2004, the appearance of high-entropy alloy breaks through the design of the original traditional rare alloy and creates a new idea of alloy design. The high-entropy mixed solid solution is composed of 5 or more than 5 elements with near-equal atomic ratio, and the high-entropy mixed solid solution can greatly reduce Gibbs free energy and stabilize a solid solution phase. Therefore, the crystal structure of the high entropy alloy is relatively simple, rather than competing complex brittle intermetallic phases. In addition, the high-entropy alloy has stable high-temperature mechanical property, excellent low-temperature fracture toughness and good room temperature performance.

High entropy alloys are a broad field with innumerable new alloy systems. At present, the research on the method is very limited. The research focus on finding a superior alloy system with excellent comprehensive mechanical properties through component regulation is always. However, how to effectively reduce material development time? We need a new idea to navigate quickly on sensitive composition and structure dependent performance exploration roads. High throughput experiments have therefore been proposed and explored.

For high-entropy alloys, there are many researches on substitution of main components, control of contents of main components, and addition of trace elements to improve the properties thereof. It would be an effective high throughput experimental means to design a continuous variation of the content of an element or elements in a sample, even in a grain, and to measure the continuous variation of its properties.

Disclosure of Invention

Based on the above discussion, the invention aims to provide a preparation method for quantitatively controlling element gradient change in a high-entropy alloy film.

In order to achieve the purpose, the invention adopts the following technical scheme:

a high-entropy alloy film capable of quantitatively controlling element content gradient change comprises the following components in atomic percentage: cr: 20-24%, Mn: 20-42%, Fe: 16-22%, Co: 13-19%, Ni: 10-13%, wherein the content of manganese element presents a large continuous gradient change, and the sum of atomic percentages of all components is 100%.

A method for preparing a high-entropy alloy film with quantitatively controlled element content and continuous gradient distribution is characterized in that magnetron sputtering is adopted to simultaneously control a direct-current power supply and a radio-frequency power supply to carry out sputtering, and further the sputtering deposition rate of required manganese elements is controlled to achieve the high-entropy alloy film with continuously changed content gradient.

The method adopted by the invention specifically comprises the following steps:

1) the clean substrate and the bottom support are fixed and placed on a suspended substrate table of the ultrahigh vacuum magnetron sputtering equipment.

2) Fixing the required high-entropy alloy target material and pure manganese target material on corresponding radio frequency and direct current power supplies.

3) High-purity argon is used as main ionized gas for glow discharge, and two targets are effectively sputtered and deposited on a substrate.

4) In the deposition process, firstly, the direct current power supply is turned on to normally start, and then the radio frequency power supply is turned on to start.

5) The power of two power supplies is controlled to carry out multiple sputtering deposition, the time of single sputtering is 30-60 min, and the intermittent time is 10-20 min.

The purity of the target material is 99.9-99.99 wt%.

The high-entropy alloy target comprises CrMnFeCoNi with a nearly equal atomic ratio.

The substrate is monocrystalline silicon (100), (111).

The purity of the high-purity argon is more than or equal to 99.999 percent.

The power of the radio frequency power supply is fixed at 110-130W, and the power of the direct current power supply is reduced to 0W from 30W at the speed of 6-10W each time.

The number of times of sputtering is 4 to 7.

Further, when the deposition in the step 4) needs to be carried out, a substrate rotating switch is opened, and the deposition is more uniform and dense.

Further, pre-sputtering is needed before formal deposition in the step 4), impurities on the surface of the target are removed, and quantitative control of the content of the film is prevented from being influenced.

The invention has the following advantages:

1. by using the method, a sample with Mn element continuously changing in a gradient manner from 20 at% to 42 at% along the thickness direction of the high-entropy alloy film is obtained.

2. The unique content change causes the structural change from the surface nano-crystal to the inner amorphous, and the nano-crystal and amorphous composite material is formed.

3. The continuous structure and performance change of the sample are measured, the influence of the content control on the high-entropy alloy can be effectively predicted, the optimal component is searched, and the design target of a high-throughput experiment is met.

Drawings

FIG. 1 is a SEM result diagram of a high-entropy alloy thin film;

(a) EDS element content change chart.

(b) Film cross-section structure diagram.

FIG. 2 is a microscopic structure diagram of a high-entropy alloy thin film obtained by TEM.

(a) Magnified image of microstructure of thin film

(b-e) diffraction patterns of the four regions in FIG. (a)

FIG. 3 is a TEM microstructure of a comparative sample of a high entropy alloy having an Mn content of about 49 at%.

Detailed Description

The present invention will be described in detail below with reference to specific examples and drawings, but the present invention is not limited thereto.

Referring to FIG. 1, a graph (a) shows the variation of 5 elements of the high-entropy alloy thin film with the thickness of the thin film (from the surface to the inside), wherein the variation range of the manganese element content is 20 at% to 42 at%, and the variation range of the contents of the other four elements is relatively small. The total thickness of the high-entropy alloy thin film is 1.78 μm as shown in the diagram (b).

Referring to fig. 2, the graph (a) shows the overall structure of the film, with the bright areas in the film being grain boundaries (due to ion thinning). Further, the microstructure of the four regions in plot (a) was characterized by diffraction, shown in plots (b-e). The diffraction spots gradually disappeared and the amorphous rings gradually formed and became bright, indicating the structural features that gradually transitioned from the surface nanocrystalline structure to the internal amorphous structure.

Referring to FIG. 3, when the content of Mn in the high-entropy alloy thin film is about 49 at% and there is no content variation along the thickness, both the high-resolution TEM image and the diffraction pattern at the upper right corner show that the sample has an amorphous structure.

Example 1

A5-element high-entropy alloy film with the components of CrMnFeCoNi is prepared on a silicon substrate by adopting an intermittent magnetron sputtering mode. And simultaneously controlling a radio frequency power supply and a direct current power supply to sputter the CrMnFeCoNi high-entropy alloy target material and the pure manganese metal target material with approximately equal atomic ratio, wherein the power of the radio frequency power supply is fixed at 120W, the power of the direct current power supply is reduced to 0W from 30W at the speed of 10W each time, the sputtering is carried out for 4 times, the single sputtering time is 60min, the intermittent time is 20min, and the total time is 5.3 hours.

The SEM test results of the obtained high-entropy alloy thin film are shown in FIG. 1, and the results show that the content of manganese in 5 elements is in a range from 20 at% to 42 at%, while the content of the other four elements is relatively small, and the total thickness of the high-entropy alloy thin film is 1.78 μm. The content gradient changes also cause structural changes (fig. 2), and the thin film structure evolves from a nanocrystalline structure on the surface to an amorphous structure inside. That is, when the content of manganese element is higher, amorphous structure formation is more facilitated. Further, we also characterized the TEM microstructure of the high entropy alloy thin film sample with no change in manganese content (about 49 at%), showing an amorphous structure, which is consistent with the trend we have concluded. Compared with other high-entropy alloy films, the film prepared by the invention has the characteristics of gradient change of element content and high flux, shows the relation between the element content and the structure, and provides an effective way for the exploration of the high-entropy alloy.

Example 2

Through intermittent magnetron sputtering, a radio frequency power supply and a direct current power supply are simultaneously controlled to sputter a CrMnFeCoNi high-entropy alloy target material and a pure manganese metal target material with approximately equal atomic ratio, wherein the power of the radio frequency power supply is fixed at 110W, the power of the direct current power supply is reduced to 0W from 30W at the speed of 7-8W each time, the sputtering is carried out for 5 times, the single sputtering time is 30min, and the intermittent time is 15min, and the total time is 3.75 hours. The film thickness was 1.72. mu.m. The high-entropy alloy film has a structure with gradient change of manganese content. Compared with other high-entropy alloy films, the film prepared by the method has both a nanocrystalline structure and an amorphous structure, and is a composite material.

Example 3

The CrMnFeCoNi high-entropy alloy target material and the pure manganese metal target material with nearly equal atomic ratio are sputtered by simultaneously controlling a radio frequency power supply and a direct current power supply in magnetron sputtering. The power of the radio frequency power supply is fixed at 130W, the power of the direct current power supply is reduced from 30W at the speed of 6-7W each time, the sputtering is carried out for 4 times, the single sputtering time is 60min, the intermittence time is 20min, and the total time is 5.3 hours. The film thickness was about 2 μm. The film prepared by the method has the characteristic of manganese content gradient. Because the composition determines the structural characteristics of the film, the film with the changed content has more structural information, and can be used as a method for high-throughput experiments.