阅读说明：本技术 一种CoCrNiCuFeMnAl高熵合金及其制备方法 (CoCrNiCuFeMnAl high-entropy alloy and preparation method thereof ) 是由 罗永安 李艳国 邹芹 罗文奇 邹娟 于 2020-04-15 设计创作，主要内容包括：本发明属于金属合金材料领域,涉及一种CoCrNiCuFeMnAl高熵合金,其包括钴粉5.2～38.03wt.％、铬粉4.5～34.53wt.％、镍粉5.17～37.92wt.％、铜粉5.68～40.25wt.％、铁粉0.2～20.61wt.％、锰粉0.5～33.45wt.％和铝粉0.3～20.03wt.％；其制备方法是首先将上述金属单质粉末在球磨机中进行机械合金化,然后将得到的高熵合金粉体进行预压成型、退火处理,再进行热压烧结,将烧结体进行退火处理,最后将退火后的烧结体表面进行打磨、抛光,去除样品烧结中残留的外界杂质以及烧结过程中边缘产生的毛刺,从而制得CoCrNiCuFeMnAl高熵合金块体材料。与传统合金相比,本发明的高熵合金具有更好的致密度、硬度和抗压强度。(The invention belongs to the field of metal alloy materials, and relates to a CoCrNiCuFeMnAl high-entropy alloy which comprises 5.2-38.03 wt% of cobalt powder, 4.5-34.53 wt% of chromium powder, 5.17-37.92 wt% of nickel powder, 5.68-40.25 wt% of copper powder, 0.2-20.61 wt% of iron powder, 0.5-33.45 wt% of manganese powder and 0.3-20.03 wt% of aluminum powder; the preparation method comprises the steps of firstly, carrying out mechanical alloying on the metal simple substance powder in a ball mill, then carrying out pre-pressing forming and annealing treatment on the obtained high-entropy alloy powder, then carrying out hot-pressing sintering, carrying out annealing treatment on a sintered body, and finally grinding and polishing the surface of the annealed sintered body to remove external impurities remained in sample sintering and burrs generated at the edge in the sintering process, thereby preparing the CoCrNiCuFeMnAl high-entropy alloy block material. Compared with the traditional alloy, the high-entropy alloy has better compactness, hardness and compressive strength.)

1. The CoCrNiCuFeMnAl high-entropy alloy is characterized by comprising the following components in percentage by mass: 5.2-38.03 wt% of cobalt powder, 4.5-34.53 wt% of chromium powder, 5.17-37.92 wt% of nickel powder, 5.68-40.25 wt% of copper powder, 0.2-20.61 wt% of iron powder, 0.5-33.45 wt% of manganese powder and 0.3-20.03 wt% of aluminum powder.

2. The CoCrNiCuFeMnAl high-entropy alloy is characterized in that the cobalt powder, the chromium powder, the nickel powder, the copper powder, the iron powder, the manganese powder and the aluminum powder are all elemental powders, the purity is 99.5%, and the mesh number is 200-500 meshes.

3. A method for the preparation of a CoCrNiCuFeMnAl high entropy alloy according to any of claims 1 and 2, characterized in that it comprises the following steps:

(1) carrying out ball milling on cobalt powder, chromium powder, nickel powder, copper powder, iron powder, manganese powder and aluminum powder in a ball mill for 20-30 h; the mass ratio of the grinding balls to the grinding materials is 10: 1-20: 1; the grinding balls are steel balls with the ball diameters of 1mm, 4mm and 6mm respectively, and the corresponding mass ratio is 1:3:6 respectively; the ball milling speed is 200-400 r/min, positive and negative rotation alternate operation is carried out, positive rotation is carried out for 1h, machine halt is carried out for 30min, reverse rotation is carried out for 1h, and cyclic reciprocation is carried out; dripping a process control agent every 10 hours in the ball milling process to obtain high-entropy alloy powder;

(2) filling the high-entropy alloy powder synthesized in the step (1) into a die, and prepressing and forming under the pressure of 200-500 MPa for 30-300 s; then annealing the pre-pressed block, wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 30-120 min;

(3) carrying out hot-pressing sintering on the pre-pressed block annealed in the step (2), wherein the sintering pressure is 20-50 MPa, the sintering temperature is 800-1000 ℃, the temperature is increased from room temperature to the target sintering temperature at the rate of 15-50 ℃/min, the temperature and pressure are kept for 10-60 min after the target sintering temperature is reached, the pressure is unloaded, and the pre-pressed block is cooled to room temperature and then taken out, so that a CoCrNiCuFeMnAl high-entropy alloy sintered body is obtained;

(4) annealing the sintered body prepared in the step (3), wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 1-10 h;

(5) and (4) grinding and polishing the surface of the sintered body annealed in the step (4), and removing external impurities remained in sample sintering and burrs generated at the edge in the sintering process, thereby preparing the CoCrNiCuFeMnAl high-entropy alloy block material.

4. The preparation method of the CoCrNiCuFeMnAl high-entropy alloy as claimed in claim 3, wherein the process control agent is industrial ethanol with an analytical purity of not less than 99.7%, and the dropping amount is 0.2-0.5 ml/10g of metal powder.

Technical Field

The invention relates to the field of metal alloy materials, in particular to a CoCrNiCuFeMnAl high-entropy alloy and a preparation method thereof.

Background

In 1995, leaves and the like break through the traditional concept of material design, and a new alloy design concept is provided on the basis of amorphous alloy, namely High inversion Alloys (HEAs). The high-entropy alloy is an alloy with higher mixed entropy, which is formed by alloying more than 5 element components according to equal atomic ratio or nearly equal atomic ratio and generally forms a solid solution. It was defined in 2004 as a high entropy alloy with a major element atomic fraction ranging from 5% to 35%. The high-entropy alloy has excellent performances which cannot be simultaneously possessed by the traditional alloy, such as high strength, high hardness, high wear resistance, high oxidation resistance, high corrosion resistance and the like, becomes one of hot spots with the most development potential in recent years, and has very high academic research value. In recent years, high entropy alloys have attracted increasing attention from material researchers.

In 2007, Chenmin et al prepared AlTiFeNiCuCr by vacuum melting_xThe multi-principal-element high-entropy alloy is a low-temperature brittle material, has good plastic deformation capacity and high strength at a high temperature of 1073K, has the hardness range of 343.7-369.3 HV, and has the tensile strength of a sample approaching 1300MPa at a temperature of 573K when x is 2 [ Chen Min, Liu Source, Lixiang, and the like]Journal of metals 2007(10) 1020-]. AlCr fusion casting by 2009 Lianmin et al in vacuum arc furnace_xThe CuFeNi high-entropy alloy shows that the as-cast structure of the alloy is a typical dendrite, has FCC and BCC structures, and increases with the value of x, the hardness of the alloy increases from 446HV to 518HV [ Lianmin, Zhang Xiyan. Cr influences the structure and hardness of the AlCrCuFeNi high-entropy alloy [ J]Non-ferrous metals, 2009,61(04):18-20]. In 2014, CoFeNiAl is prepared by mechanical alloying and SPS sintering_0.6Ti_0.4And CrCoFeNiAl_0.6Ti_0.4The block high-entropy alloy shows that: cr does not affect CoFeNiAl_0.6Ti_0.4The alloying sequence of the high-entropy alloy influences the crystal structure after complete alloying, so that C isoFeNiAl_0.6Ti_0.4The high-entropy alloy is changed into an fcc + bcc structure from an original single fcc structure, and after SPS sintering, CoFeNiAl is obtained_0.6Ti_0.4The high-entropy alloy mainly comprises an fcc + bcc main phase and a trace bcc phase, and the addition of Cr element promotes the alloy to be converted into the fcc main phase and the trace bcc phase (strong anvilness, old balance, square wisdom, Cr to CoFeNiAl_0.6Ti_0.4Influence of alloying behavior and organization [ J]Rare metal materials and engineering, 2014(10) 2411-]. The FeCoCrNiMn high-entropy alloy is prepared by mechanical alloying and hot-pressing sintering in 2018 Chenghu and the like, the plastic strain of the alloy is increased from 4.4 percent to 38.2 percent along with the increase of the hot-pressing sintering temperature from 700 ℃ to 1000 ℃, the yield strength is reduced from 1682MPa to 774MPa, and the FeCoCrNiMn high-entropy alloy sintered for 1 hour at 800 ℃ and 900 ℃ has better comprehensive mechanical properties (Chenghu, Xiyan Chong, Tang Dynasty, and the like)].Transactions of Nonferrous Metals Society of China,2018,28(07):1360-1367]. The NbMoCrTiAl high-entropy alloy powder is prepared by ball milling and spark plasma sintering in the color of 2019, and the like, and the change rule of the microstructure and hardness of the NbMoCrTiAl high-entropy alloy prepared by spark plasma sintering at different temperatures is discussed. The results show that: under the conditions of the rotating speed of 300r/min and the ball-material ratio of 10:1, the powder is ball-milled for 60 hours and only reaches partial alloying; under the conditions of ball-material ratio of 10:1 and ball milling for 50h, the ball milling rotating speed is higher than 400r/min, and then the single BCC solid solution high-entropy alloy can be obtained. Along with the increase of sintering temperature (1400-1600 ℃), the number of second phases of the NbMoCrTiAl high-entropy alloy is reduced and the size of the second phases is increased, so that the hardness of the alloy is reduced from 956HV to 791HV [ Yanjiahui, Likailing, Wangqi, and the like]Material guide, 2019,33(10):1671-]。

At present, the preparation methods of the block high-entropy alloy mainly comprise vacuum melting, spark plasma sintering, hot-pressing sintering, high-pressure sintering and the like. For bulk materials, arc melting has several drawbacks, such as the inability to control low boiling elements when the boiling point of a major element is near or below the melting point of some other element. Mechanical Alloying (MA) is a solid-state non-equilibrium high-energy ball milling process, and can realize alloying among high-entropy alloy elements with large melting point difference. The Spark Plasma Sintering (SPS) can be rapidly sintered to prepare the high-entropy alloy, and the sintering process can inhibit the growth of crystal grains to obtain a block material with high density and uniform structure. The hot-pressing sintering can provide larger sintering pressure on the basis of sintering, and the high-entropy alloy with larger size, fine crystal grains and uniformly distributed tissues can be prepared hopefully while mechanical alloying is combined. However, in the traditional hot-pressing sintering process, because a large amount of impurities are adsorbed by the thin high-entropy alloy powder and the pressure of hot-pressing equipment is limited, the density of the sintered high-entropy alloy is low, and the mechanical property cannot be fully expressed.

Disclosure of Invention

The invention aims to provide a CoCrNiCuFeMnAl high-entropy alloy and a preparation method thereof, which have better compactness, hardness and compressive strength.

In order to solve the technical problems, the invention provides the following technical scheme:

a CoCrNiCuFeMnAl high-entropy alloy comprises the following components in percentage by mass: 5.2-38.03 wt% of cobalt powder, 4.5-34.53 wt% of chromium powder, 5.17-37.92 wt% of nickel powder, 5.68-40.25 wt% of copper powder, 0.2-20.61 wt% of iron powder, 0.5-33.45 wt% of manganese powder and 0.3-20.03 wt% of aluminum powder.

Preferably, the cobalt powder, the chromium powder, the nickel powder, the copper powder, the iron powder, the manganese powder and the aluminum powder are all single substance powder, the purity is 99.5%, and the mesh number is 200-500 meshes.

The invention also provides a preparation method of the CoCrNiCuFeMnAl high-entropy alloy, which comprises the following steps:

(1) carrying out ball milling on cobalt powder, chromium powder, nickel powder, copper powder, iron powder, manganese powder and aluminum powder in a ball mill for 20-30 h; the mass ratio of the grinding balls to the grinding materials is 10: 1-20: 1; the grinding balls are steel balls with the ball diameters of 1mm, 4mm and 6mm respectively, and the corresponding mass ratio is 1:3:6 respectively; the ball milling speed is 200-400 r/min, positive and negative rotation alternate operation is carried out, positive rotation is carried out for 1h, machine halt is carried out for 30min, reverse rotation is carried out for 1h, and cyclic reciprocation is carried out; dripping a process control agent every 10 hours in the ball milling process to obtain high-entropy alloy powder;

(2) filling the high-entropy alloy powder synthesized in the step (1) into a die, and prepressing and forming under the pressure of 200-500 MPa for 30-300 s; then annealing the pre-pressed block, wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 30-120 min;

(3) carrying out hot-pressing sintering on the pre-pressed block annealed in the step (2), wherein the sintering pressure is 20-50 MPa, the sintering temperature is 800-1000 ℃, the temperature is increased from room temperature to the target sintering temperature at the rate of 15-50 ℃/min, the temperature and pressure are kept for 10-60 min after the target sintering temperature is reached, the pressure is unloaded, and the pre-pressed block is cooled to room temperature and then taken out, so that a CoCrNiCuFeMnAl high-entropy alloy sintered body is obtained;

(4) annealing the sintered body prepared in the step (3), wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 1-10 h;

(5) and (4) grinding and polishing the surface of the sintered body annealed in the step (4), and removing external impurities remained in sample sintering and burrs generated at the edge in the sintering process, thereby preparing the CoCrNiCuFeMnAl high-entropy alloy block material.

Preferably, the process control agent is industrial ethanol with analytical purity of more than or equal to 99.7%, and the dropping amount is 0.2-0.5 ml/10g of metal powder.

Compared with the prior art, the invention has the following beneficial effects:

the high-entropy alloy has better hardness and compressive strength at a lower sintering temperature, improves the density of a sintered body by utilizing a higher pre-pressure and annealing process, reduces the gaps of the sintered body, and solves the problem of insufficient mechanical properties caused by lower density of the traditional high-entropy alloy sintered body.

Detailed Description

Exemplary embodiments, features and performance aspects of the present invention are described in detail below.

A CoCrNiCuFeMnAl high-entropy alloy comprises the following components in percentage by mass: 5.2-38.03 wt% of cobalt powder, 4.5-34.53 wt% of chromium powder, 5.17-37.92 wt% of nickel powder, 5.68-40.25 wt% of copper powder, 0.2-20.61 wt% of iron powder, 0.5-33.45 wt% of manganese powder and 0.3-20.03 wt% of aluminum powder.

Preferably, the cobalt powder, the chromium powder, the nickel powder, the copper powder, the iron powder, the manganese powder and the aluminum powder are all single substance powder, the purity is 99.5%, and the mesh number is 200-500 meshes.

A preparation method of a CoCrNiCuFeMnAl high-entropy alloy comprises the following steps:

(1) carrying out ball milling on cobalt powder, chromium powder, nickel powder, copper powder, iron powder, manganese powder and aluminum powder in a ball mill for 20-30 h; the mass ratio of the grinding balls to the grinding materials is 10: 1-20: 1; the grinding balls are steel balls with the ball diameters of 1mm, 4mm and 6mm respectively, and the corresponding mass ratio is 1:3:6 respectively; the ball milling speed is 200-400 r/min, positive and negative rotation alternate operation is carried out, positive rotation is carried out for 1h, machine halt is carried out for 30min, reverse rotation is carried out for 1h, and cyclic reciprocation is carried out; dripping a process control agent every 10 hours in the ball milling process to obtain high-entropy alloy powder;

(2) filling the high-entropy alloy powder synthesized in the step (1) into a die, and prepressing and forming under the pressure of 200-500 MPa for 30-300 s; then annealing the pre-pressed block, wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 30-120 min;

(3) carrying out hot-pressing sintering on the pre-pressed block annealed in the step (2), wherein the sintering pressure is 20-50 MPa, the sintering temperature is 800-1000 ℃, the temperature is increased from room temperature to the target sintering temperature at the rate of 15-50 ℃/min, the temperature and pressure are kept for 10-60 min after the target sintering temperature is reached, the pressure is unloaded, and the pre-pressed block is cooled to room temperature and then taken out, so that a CoCrNiCuFeMnAl high-entropy alloy sintered body is obtained;

(4) annealing the sintered body prepared in the step (3), wherein the annealing temperature is 300-600 ℃, and the heat preservation time is 1-10 h;

(5) and (4) grinding and polishing the surface of the sintered body annealed in the step (4), and removing external impurities remained in sample sintering and burrs generated at the edge in the sintering process, thereby preparing the CoCrNiCuFeMnAl high-entropy alloy block material.

Preferably, the process control agent is industrial ethanol with analytical purity of more than or equal to 99.7%, and the dropping amount is 0.2-0.5 ml/10g of metal powder.