阅读说明：本技术 一种AlCrMoNbTaTi高熵合金材料及其制备方法 (AlCrMoNbTaTi high-entropy alloy material and preparation method thereof ) 是由 肖逸锋 郭景平 张汭 吴靓 张乾坤 陈宇 陈愚 于 2020-12-16 设计创作，主要内容包括：本发明涉及一种耐高温、抗氧化的AlCrMoNbTaTi高熵合金材料及其制备方法,其元素成分为等摩尔比1:1:1:1:1:1的AlCrMoNbTaTi,其铸态组织由BCC固溶体、少量A15相和Laves相组成。其制备方法如下：(1)超声处理：用丙酮溶液和无水乙醇清洗各材料备用；(2)称量：以等摩尔比称取各材料；(3)熔炼：使用非自耗真空电弧熔炼炉对称量配好的材料进行多次重复熔炼制备铸态高熵合金。(4)热处理：采用真空管式加热炉对铸态高熵合金进行1200-1350℃,保温3-5h的均匀化退火。退火处理提高了组织的均匀性,并析出了弥散分布的细小颗粒。该合金具有优异的耐高温性能,在高温结构领域有着广泛的应用前景。(The invention relates to a high-temperature-resistant and oxidation-resistant AlCrMoNbTaTi high-entropy alloy material and a preparation method thereof, wherein the element components of the high-temperature-resistant and oxidation-resistant AlCrMoNbTaTi high-entropy alloy material are AlCrMoNbTaTi with an equal molar ratio of 1:1:1:1:1:1, and the as-cast structure of the high-temperature-resistant and oxidation-resistant AlCrMoNbTaTi high-entropy alloy material is composed of a BCC solid solution. The preparation method comprises the following steps: (1) ultrasonic treatment: cleaning each material with acetone solution and absolute ethyl alcohol for later use; (2) weighing: weighing the materials according to an equimolar ratio; (3) smelting: and repeatedly smelting the weighed and proportioned material for many times by using a non-consumable vacuum arc smelting furnace to prepare the as-cast high-entropy alloy. (4) And (3) heat treatment: and carrying out homogenization annealing on the cast-state high-entropy alloy at 1200-1350 ℃ by using a vacuum tube type heating furnace for heat preservation for 3-5 h. The annealing treatment improves the uniformity of the structure and separates out the fine particles which are dispersed and distributed. The alloy has excellent high temperature resistance and wide application prospect in the field of high-temperature structures.)

1.A high-temperature-resistant and oxidation-resistant AlCrMoNbTaTi high-entropy alloy material is characterized by comprising the following steps of:

the method comprises the following steps: respectively cleaning Al, Cr, Mo, Nb, Ta and Ti metal materials with the purity of not less than 99.7 wt.% by using an ultrasonic treatment instrument, and taking out for later use after cleaning; wherein, the forms of the six materials of Al, Cr, Mo, Nb, Ta and Ti are all sheet, block or large particle except powder.

Step two: in order to ensure the accuracy of the experiment and reduce the experimental error, a ten-thousandth electronic balance scale is adopted for weighing, six materials of Al, Cr, Mo, Nb, Ta and Ti after ultrasonic cleaning and cleaning in the step one are accurately weighed according to the equal molar ratio of 1:1:1:1:1:1, and the materials wait for smelting.

Step three: opening a furnace door of the non-consumable vacuum arc melting furnace, putting the raw materials weighed and proportioned in the second step into a copper mold crucible of the non-consumable vacuum arc melting furnace, stacking the raw materials layer by layer in a mode that the material with the lowest melting point is placed at the lowest layer and the material with the highest melting point is placed at the uppermost layer, placing the pure titanium sheet into a melting tank at the middle, closing the furnace door after the placement is finished, and screwing a sample chamber sealing knob.

Step four: opening the vacuum pump, vacuumizing the sample chamber until the vacuum degree is lower than 5.0 multiplied by 10^-3Is MPa is filled inVacuumizing again to a vacuum degree of less than 5.0X 10 after the high-purity argon reaches 0.05MPa^-3MPa; the above operation is repeated several times, and the sample chamber is sufficiently cleaned to reduce the content of impurity gases.

Step five: after the sample chamber is fully cleaned, argon is injected to reach half atmospheric pressure, and arc starting smelting is started. Firstly, melting pure titanium sheets, consuming residual oxygen in a sample chamber as much as possible, and then melting samples in other copper mold crucibles one by one. Repeatedly melting each sample for 8-10 times, turning over the sample after each melting, wherein the melting time is 1-2min each time to ensure that all elements are uniformly mixed. After furnace cooling, the cast AlCrMoNbTaTi high-entropy alloy material is prepared, the structure of the alloy material is a dendritic structure, and a small amount of A15 phase dendrites and Laves phases exist among the dendrites.

Step six: putting the as-cast high-entropy alloy obtained by smelting into a vacuum tube type heating furnace for carrying out homogenization annealing at 1200-1350 ℃ and keeping the temperature for 3-5 h. The AlCrMoNbTaTi high-entropy alloy material is obtained after furnace cooling, and the structure of the AlCrMoNbTaTi high-entropy alloy material is changed into a more uniform dendritic crystal and a large number of uniformly distributed second-phase black particles.

2.A preparation method of a high-entropy AlCrMoNbTaTi alloy material with high temperature resistance and oxidation resistance is characterized by comprising the following steps:

the method comprises the following steps: respectively cleaning Al, Cr, Mo, Nb, Ta and Ti metal materials with the purity of not less than 99.7 wt.% by using an ultrasonic treatment instrument, and taking out for later use after cleaning; wherein, the forms of the six materials of Al, Cr, Mo, Nb, Ta and Ti are all sheet, block or large particle except powder.

Step two: in order to ensure the accuracy of the experiment and reduce the experimental error, a ten-thousandth electronic balance scale is adopted for weighing, six materials of Al, Cr, Mo, Nb, Ta and Ti after ultrasonic cleaning and cleaning in the step one are accurately weighed according to the equal molar ratio of 1:1:1:1:1:1, and the materials wait for smelting.

Step three: opening a furnace door of the non-consumable vacuum arc melting furnace, putting the raw materials weighed and proportioned in the second step into a copper mold crucible of the non-consumable vacuum arc melting furnace, stacking the raw materials layer by layer in a mode that the material with the lowest melting point is placed at the lowest layer and the material with the highest melting point is placed at the uppermost layer, placing the pure titanium sheet into a melting tank at the middle, closing the furnace door after the placement is finished, and screwing a sample chamber sealing knob.

Step four: opening the vacuum pump, vacuumizing the sample chamber until the vacuum degree is lower than 5.0 multiplied by 10^-3Introducing high-purity argon to 0.05MPa, vacuumizing again to a vacuum degree lower than 5.0 × 10^-3MPa; the above operation is repeated several times, and the sample chamber is sufficiently cleaned to reduce the content of impurity gases.

Step five: after the sample chamber is fully cleaned, argon is injected to reach half atmospheric pressure, and arc starting smelting is started. Firstly, melting pure titanium sheets, consuming residual oxygen in a sample chamber as much as possible, and then melting samples in other copper mold crucibles one by one. Repeatedly melting each sample for 8-10 times, turning over the sample after each melting, wherein the melting time is 1-2min each time to ensure that all elements are uniformly mixed. After furnace cooling, the cast AlCrMoNbTaTi high-entropy alloy material is prepared, the structure of the alloy material is a dendritic structure, and a small amount of A15 phase and Laves phase exist among the dendritic structure.

Step six: putting the as-cast high-entropy alloy obtained by smelting into a vacuum tube type heating furnace for carrying out homogenization annealing at 1200-1350 ℃ and keeping the temperature for 3-5 h. The AlCrMoNbTaTi high-entropy alloy material is obtained after furnace cooling, and the structure of the AlCrMoNbTaTi high-entropy alloy material is changed into a more uniform dendritic crystal and a large number of uniformly distributed second-phase black particles.

Technical Field

The invention relates to a high-entropy alloy material and a preparation method thereof, in particular to a high-entropy alloy material with high temperature resistance and oxidation resistance and an AlCrMoNbTaTi and a preparation method thereof, belonging to the technical field of alloy material preparation.

Background

In the 90 s of the 20 th century, Taiwan scholars in China originally proposed a novel alloy design concept, namely multi-principal element alloy. The multi-principal element alloy is an alloy with more than 5 constituent elements and 5 to 35 atomic percent of each main element. The alloy has many component types and high content, and the mixed entropy of the atomic arrangement is high, so the multi-principal-element alloy is also called multi-principal-element high-entropy alloy. The multi-principal-element high-entropy alloy breaks through the traditional alloy design mode based on one alloy element, can obtain a combined alloy with the microstructure simplification, the nanometer precipitate, the amorphous structure, the nanometer crystal grain and other tissue characteristics, and the excellent performances of high hardness, wear resistance, high strength, corrosion resistance, high temperature creep resistance, high temperature oxidation resistance, tempering softening resistance and the like by adjusting the alloy components, and has wide application in industrial production.

The AlCrMoNbTaTi high-entropy alloy prepared by the method has a single body-centered cubic structure, shows the advantages of high hardness, strong high-temperature oxidation resistance, high-temperature softening resistance and the like, and has considerable research value and development potential in the high-temperature field.

Disclosure of Invention

The invention aims to provide a high-temperature-resistant and oxidation-resistant CrAlNbTiVZr high-entropy alloy material and a preparation method thereof. The alloy has a simple body-centered cubic structure, has the characteristics of good room temperature plasticity and high temperature strength, and can be in service at high temperature for a long time.

The technical scheme adopted by the invention to solve the technical problems is as follows: the high-entropy alloy material comprises AlCrMoNbTaTi, wherein the molar ratio of Al to Cr to Mo to Nb to Ta to Ti is 1:1:1:1: 1. The purity of Al, Cr, Mo, Nb, Ta and Ti materials adopted by the high-entropy alloy is not less than 99.7 wt.%, and the raw materials are all in a shape of a sheet, a block or a large particle except powder.

The technical solution adopted by the present invention to solve the above technical problems further includes: a preparation method of a high-entropy alloy material with AlCrMoNbTaTi components is characterized by comprising the following steps:

the method comprises the following steps: respectively cleaning Al, Cr, Mo, Nb, Ta and Ti metal materials with the purity of not less than 99.7 wt.% by using an ultrasonic treatment instrument, and taking out for later use after cleaning; wherein, the forms of the six materials of Al, Cr, Mo, Nb, Ta and Ti are all sheet, block or large particle except powder.

Step two: in order to ensure the accuracy of the experiment and reduce the experimental error, a ten-thousandth electronic balance scale is adopted for weighing, six materials of Al, Cr, Mo, Nb, Ta and Ti after ultrasonic cleaning and cleaning in the step one are accurately weighed according to the equal molar ratio of 1:1:1:1:1:1, and the materials wait for smelting.

Step three: opening a furnace door of the non-consumable vacuum arc melting furnace, putting the raw materials weighed and proportioned in the second step into a copper mold crucible of the non-consumable vacuum arc melting furnace, stacking the raw materials layer by layer in a mode that the material with the lowest melting point is placed at the lowest layer and the material with the highest melting point is placed at the uppermost layer, placing the pure titanium sheet into a melting tank at the middle, closing the furnace door after the placement is finished, and screwing a sample chamber sealing knob.

Step four: opening the vacuum pump, vacuumizing the sample chamber until the vacuum degree is lower than 5.0 multiplied by 10^-3Introducing high-purity argon to 0.05MPa, vacuumizing again to a vacuum degree lower than 5.0 × 10^-3MPa; the above operation is repeated several times, and the sample chamber is sufficiently cleaned to reduce the content of impurity gases.

Step five: after the sample chamber is fully cleaned, argon is injected to reach half atmospheric pressure, and arc starting smelting is started. Smelting pure titanium particles, consuming residual oxygen in a sample chamber as much as possible, and then smelting samples in other copper mold crucibles one by one. Repeatedly melting each sample for 8-10 times, turning over the sample after each melting, wherein the melting time is 1-2min each time to ensure that all elements are uniformly mixed. And cooling along with the furnace to obtain the as-cast AlCrMoNbTaTi high-entropy alloy material.

Step six: putting the as-cast high-entropy alloy obtained by smelting into a vacuum tube type heating furnace for carrying out homogenization annealing at 1200-1350 ℃ and keeping the temperature for 2-4 h. And cooling along with the furnace to obtain the AlCrMoNbTaTi high-entropy alloy material.

The invention has the beneficial effects that:

1. the invention provides a high-temperature-resistant and oxidation-resistant AlCrMoNbTaTi high-entropy alloy material, which mainly comprises a BCC solid solution phase, a small amount of A15 phase and a Laves phase, and has a uniform alloy structure. The alloy has good strength and hardness at room temperature and high temperature, has good high temperature resistance, and has wide application prospect in the high temperature field.

2. The invention provides a method for preparing a high-entropy alloy by a non-consumable vacuum arc melting process, which is used for preparing a high-entropy alloy material with high toughness, excellent corrosion resistance and high temperature resistance, makes up for the defects of the traditional alloy, has excellent mechanical properties at room temperature and high temperature, and meets the application requirements of the corrosion-resistant and high-temperature-resistant material.

3. Al and Cr elements are added into the alloy, so that a compact oxide film can be generated to cover the surface of the alloy, and oxygen is prevented from directly contacting the alloy, thereby improving the oxidation resistance of the alloy.

4. The invention provides an annealing treatment process for an as-cast high-entropy alloy through a vacuum tube type heating furnace, which achieves the aim of more uniformization of tissues and components and can separate out dispersed fine particles to strengthen the strength and hardness of the alloy.

Detailed Description

The following specific examples are provided to illustrate the manner and process capabilities of the present invention, and other advantages and benefits of the present invention will become apparent to those skilled in the art from the disclosure herein.

Designing AlCrMoNbTaTi high-entropy alloy components.

The embodiment is an AlCrMoNbTaTi high-entropy alloy consisting of six elements of Al, Cr, Mo, Nb, Ta and Ti, wherein the molar ratio of Al to Cr to Mo to Nb to Ta to Ti is 1:1:1:1: 1.

And 2, preparing the AlCrMoNbTaTi high-entropy alloy.

The preparation of the high-entropy alloy is the most critical step and comprises the following steps:

1) preparing raw materials: the alloy smelting raw materials adopted by the invention are high-purity (the purity is not less than 99.5%) Al, Cr, Mo, Nb, Ta and Ti materials, and the shapes of the raw materials are all sheet, block or large particle except powder.

2) Ultrasonic treatment: placing Al, Cr, Mo, Nb, Ta and Ti materials in a container, adding an acetone solution, placing in an ultrasonic oscillator for cleaning for 15-30 min, pouring ethanol after oscillation, repeating the same steps once, and then placing in a drying box for drying to obtain the ultrasonically-treated Al, Cr, Mo, Nb, Ta and Ti materials.

3) Weighing: the Cr, Al, Nb, Ti, V and Zr materials are accurately weighed and proportioned according to the equimolar proportion and are prepared for smelting and preparing the alloy.

4) Smelting and annealing treatment: firstly, placing weighed materials in a copper mold crucible, placing pure titanium particles in a most middle smelting tank, closing a furnace door after the placing is finished, and screwing a sample chamber sealing knob; ② starting vacuum pump to vacuumize when the vacuum degree reaches 5X 10^-3After Pa, filling high-purity argon until the pressure in the furnace reaches 0.05-0.08MPa, and repeating the step for 2-3 times; the purpose of repeated vacuum pumping is gas washing, so that impurity gas in the smelting furnace is minimized as much as possible; filling argon until the pressure in the furnace reaches about half atmospheric pressure after the gas is washed, and then opening an arc power supply to prepare for smelting; melting the pure titanium particles before melting the sample, wherein the purpose is to consume residual oxygen in the furnace; fourthly, in the smelting process, in order to enable the raw materials to be mixed uniformly better, after the alloy is smelted each time, the arc is kept for 60-120s, the alloy block is turned over after being cooled, the smelting is stopped after the operation is repeated for more than 5-8 times, the alloy is cooled to the room temperature along with the furnace, and then the furnace is opened to take out a sample, and finally the AlCrMoNbTaTi high-entropy alloy ingot is obtained; sixthly, putting the cast-state high-entropy alloy obtained after smelting into a vacuum tube type heating furnace, heating to 1200-1350 ℃, preserving the heat for 3-5 hours, and then cooling the furnace to room temperature to obtain the homogenized and annealed AlCrMoNbTaTi high-entropy alloy.

3. Structure and performance analysis of AlCrMoNbTaTi high-entropy alloy

The obtained ingot is cut into square samples with the size of 4mm multiplied by 3mm by utilizing linear cutting, the samples are carefully ground by using metallographic abrasive paper of 800#, 1200#, 1500# and 2000#, and then a polishing machine is used for carrying out tissue and performance analysis after polishing.

(1) Microstructural analysis

And observing the tissue morphology of the test sample by using a scanning electron microscope. The cast structure is a dendritic crystal structure, and a small amount of A15 fine dendritic crystals and Laves phases exist among the dendrites; the crystal grains generated by the AlCrMoNbTaTi high-entropy alloy after the homogenization annealing treatment are in a dendritic form and have fine black particles which are dispersed and distributed on a matrix.

(2) Microhardness determination and analysis

The hardness of the test piece was measured with a microhardness tester model HV-1000 having a test force of 9.807N (1kgf) and a load of 15 s. And selecting 10 different positions for measuring the microhardness of the sample, removing the highest hardness value and the lowest hardness value, taking the average value of the rest hardness values as the microhardness value of the sample, and finally obtaining the microhardness value of the alloy, wherein the microhardness value is 650.3 HV.

(3) Determination and analysis of Oxidation resistance

The polished test sample is immersed into a 1mol/L H2SO4 solution and a 3.5 wt.% NaCl solution for 10 days, the weight change before and after corrosion is analyzed, the electrochemical test is carried out on the polished sample by using an electrochemical workstation with the model number of CS2350, and the corrosion behavior of the high-entropy alloy in the 1mol/L H2SO4 solution and the 3.5 wt.% NaCl solution is researched. The CrVNiHfNb high-entropy alloy has small mass change before and after corrosion in a 1mol/L H2SO4 solution and a 3.5 wt.% NaCl solution, and the surface of the alloy is almost unchanged; the corrosion potentials of the alloy in a 1mol/L H2SO4 solution and a 3.5 wt.% NaCl solution are not very different and are both relatively low. The AlCrMoNbTaTi high-entropy alloy prepared by the method has excellent corrosion resistance.

Example results summary:

the invention obtains the annealed AlCrMoNbTaTi alloy by adopting a heat treatment method on the basis of preparing the high-entropy alloy by vacuum melting. Al and Cr elements are added into the alloy, and because the Al and Cr elements can generate compact oxide films to cover the surface of the alloy and prevent oxygen from directly contacting the alloy, the oxidation resistance of the alloy is improved, the structure is more uniform by a homogenization heat treatment method, and hard particles are dispersed and distributed on a matrix, so that the strength and the hardness of the alloy are improved. The original performance of the matrix is greatly improved by heat treatment, the toughness, plasticity and hardness of the alloy are superior to those of other traditional high-entropy alloys, and the alloy has great development potential and scientific research value.

The above-described embodiments are merely exemplary and not intended to limit the present invention in any way, and any simple modifications, equivalent variations and modifications made to the above-described embodiments in accordance with the technical spirit of the present invention are within the scope of the present invention.