阅读说明：本技术 一种轻质高强耐蚀高熵合金及其制备方法 (Light high-strength corrosion-resistant high-entropy alloy and preparation method thereof ) 是由 马爱斌 季承维 江静华 宋丹 陈建清 于 2019-11-27 设计创作，主要内容包括：本发明公开了一种低成本的轻质高强耐蚀高熵合金及其制备方法,该合金化学成分按原子百分比为：Al 34%~36%,Mg 15%~25%,Zn 29%~31%,Cu4%~6%,Si 5%~15%。该合金采用传统的氩气保护气氛下的电阻炉进行熔炼,部分元素采用中间合金添加、以不同的温度分开熔炼易烧损元素及其他元素、最后一次重熔冷却方式采用风冷10~15秒后水冷,成功制备了大尺寸的轻质高熵合金铸锭。本发明获得的高熵合金原子尺寸差δ较小,混合晗?H<Sub>mix</Sub>接近0,可形成简单的晶体结构,同时该合金具备成本低、密度小、强度大、耐蚀性强的优点；本发明设计的制备方法简单易实施、能耗低、烧损率低、可实现大规模的工业生产。(The invention discloses a low-cost light high-strength corrosion-resistant high-entropy alloy and a preparation method thereof, wherein the alloy comprises the chemical components of, by atomic percentage, 34% of Al, ~ 36%, 15% of Mg, ~ 25%, 29% of Zn, ~ 31%, 4% of Cu, ~ 6% of Si, 5% of Si, ~ 15%, the alloy is smelted by a traditional resistance furnace under the argon protective atmosphere, a part of elements are added by intermediate alloy, elements which are easy to burn and damage are separately smelted at different temperatures and other elements are separately smelted, and a final remelting cooling mode is adopted to carry out air cooling for 10 ~ 15 seconds and then is cooled by water, so that a large-size light high-entropy alloy ingot is successfully prepared mix Close to 0, a simple crystal structure can be formed, and meanwhile, the alloy has the advantages of low cost, small density, high strength and strong corrosion resistance; the preparation method designed by the invention is simple and easy to implement, low in energy consumption and easy to burnLow loss rate and large-scale industrial production.)

1. The light high-strength corrosion-resistant high-entropy alloy is characterized by comprising 34% of Al ~ 36%, 15% of Mg ~ 25%, 29% of Zn ~ 31%, 4% of Cu ~ 6% and 5% of Si ~ 15% in atomic mole percentage.

2. The light weight, high strength, corrosion resistant and high entropy alloy of claim 1, wherein the atomic size difference delta of the high entropy alloy is less than or equal to 6.6%, and the mixing break Hmix is negative.

3. The preparation method of the light high-strength corrosion-resistant high-entropy alloy is characterized by comprising the following steps

Preparing raw materials of Zn, Al-Si intermediate alloy, Cu and Mg according to the mol percentage, wherein Al is 34 percent ~ 36 percent, Mg is 15 percent ~ 25 percent, Zn is 29 percent ~ 31 percent, Cu is 4 percent ~ 6 percent, and Si is 5 percent ~ 15 percent;

putting prepared raw materials of Zn, Al-Si intermediate alloy and Cu into a graphite crucible, putting the graphite crucible into a resistance furnace for smelting, and introducing argon as protective gas;

after the set time of smelting, putting Mg into a crucible to be continuously smelted until alloy molten slurry is formed;

and pouring the alloy molten slurry in the crucible into a mold for cooling to obtain the light high-entropy alloy cast ingot.

4. The method for preparing the light-weight high-strength corrosion-resistant high-entropy alloy as claimed in claim 3, wherein the raw materials Zn, Al-Si intermediate alloy and Cu are sequentially Zn, Al-Si intermediate alloy and Cu from bottom to top in the crucible.

5. The method for preparing the light-weight, high-strength, corrosion-resistant and high-entropy alloy according to claim 3, wherein the smelting temperature of the Zn, the Al-Si master alloy and the Cu is 750 ℃ and ~ 780 ℃.

6. The method for preparing the light-weight, high-strength, corrosion-resistant and high-entropy alloy according to claim 3, wherein the melting temperature of Mg is 680 ℃ ~ 700 ℃.

7. The preparation method of the light-weight high-strength corrosion-resistant high-entropy alloy according to claim 3, wherein the alloy melt slurry in the crucible is poured into a mold for cooling, and then repeatedly remelted for 3 times to obtain a light-weight high-entropy alloy ingot, wherein the remelting temperature is set to be 720 ℃ and ~ 750 ℃.

8. The method for preparing the light-weight high-strength corrosion-resistant high-entropy alloy according to claim 3, wherein the purity of the raw materials Al, Mg, Zn, Cu and Al-Si master alloy block is more than 99.9%.

9. The preparation method of the light weight, high strength, corrosion resistant and high entropy alloy of claim 7, wherein the cooling is performed after the final remelting, and the cooling method is performed by air cooling for 10 ~ 15 seconds and then water cooling to a set temperature.

10. The preparation method of the light-weight high-strength corrosion-resistant high-entropy alloy as claimed in claim 3, wherein the smelting temperature of Zn, Al-Si master alloy and Cu is 750 ℃ and ~ 780 ℃, the smelting time is 20 ~ 30 minutes, the smelting temperature of Mg is 680 ℃ and ~ 700 ℃, and the smelting time is 20 ~ 30 minutes.

Technical Field

The invention relates to an alloy, in particular to a light high-strength corrosion-resistant high-entropy alloy and a preparation method thereof.

Background

The Taiwan scholars, all over the leaves, firstly put forward a new alloy design idea in 2004, and prepare a multi-principal-element high-entropy alloy which is different from the traditional alloy. The high-entropy alloy is formed by mixing 5 or more than 5 (generally not more than 13) metals with equal molar ratio or nearly equal molar ratio, the atomic percent of each component is not less than 5% and not more than 35%, and the high-entropy alloy does not contain the primary and secondary elements. The high-entropy alloy has a simple microstructure and excellent performances such as high strength, high hardness, high wear resistance, high corrosion resistance and the like which cannot be compared with the traditional alloy, and has great development and use values.

Al, Fe, Co, Cr, Ti, Cu, Ni, V and Mn are used for preparing high-entropy alloy in the early stage, however, the high-entropy alloy which selects Al, Co, Cr, Cu, Fe, Mn, Ni, V and the like as the constituent elements has the advantages of mechanical property, but the alloy has large specific gravity and is not suitable for preparing airplanes, automobiles, ships and the like.

At present, methods for preparing the bulk light high-entropy alloy generally comprise a smelting method and a mechanical alloying method, wherein the smelting method mainly comprises an electric arc smelting method and an induction smelting method. The arc melting method is a method for melting metal by utilizing an arc generated between an electrode and a substance to be melted or between two electrodes, and is also the most extensive method for preparing high-entropy alloy, and is generally used for melting high-melting-point high-entropy alloy, and when the constituent elements comprise low-melting-point elements such as Mg, Zn and the like, the burning loss is extremely large; the induction melting is to utilize eddy current generated in the electromagnetic induction process to melt metal, and can be used for melting high-entropy alloy with low melting point, but the method has the disadvantages of great electric energy consumption and high cost; in addition, in the prior art, when a resistance furnace is used for smelting, the burning loss of low-melting-point elements is difficult to control, so that the light high-entropy alloy is prepared without adopting the resistance furnace for smelting generally, and the mechanical alloying method is to perform long-time ball milling on metal powder or alloy powder through a ball mill to generate atomic diffusion so as to prepare alloyed powder. After the powder is fully alloyed, the powder can be directly pressed and formed or solidified by adopting spark plasma sintering to obtain the high-entropy alloy block. The method can avoid the evaporation loss of alloy components, but because the adopted raw materials are powder, the raw materials are required to be prevented from contacting with air as much as possible so as not to be oxidized, in addition, the powder is easy to explode, the instability factor is large, and the mechanical alloying method is influenced by a die and is usually used for preparing the high-entropy alloy with small size and simple shape.

Therefore, the design of the light high-entropy alloy with small specific gravity and high strength and the preparation method meeting the requirements of low cost and large size industrial production are the difficult problems which need to be solved urgently in the field of the high-entropy alloy at present.

Disclosure of Invention

The invention provides a light high-entropy alloy for solving the problem of large specific gravity of the existing high-entropy alloy, and the high-entropy alloy has the advantages of low cost, small density, high compressive strength and excellent corrosion resistance, and is suitable for the fields of aerospace, transportation and the like.

The light high-entropy alloy comprises Al, Mg, Zn, Cu and Si, wherein the atomic percentages of the elements Al, Mg, Zn, Cu and Si are 34% to ~%, 15% to ~% to Zn29% to ~%, 54% to ~% to Cu and 5% to ~% to

Further, the atomic size difference delta of the high-entropy alloy is less than or equal to 6.6 percent, and the mixing break is negative and close to 0.

The invention also provides a preparation method of the light high-entropy alloy, the preparation method adopts a resistance furnace to smelt raw materials, the temperature in the smelting process is easy to control, the metal loss is less, and the energy consumption is low.

The preparation method of the light high-entropy alloy comprises the following steps:

preparing raw materials of Zn, Al-Si intermediate alloy, Cu and Mg;

putting prepared raw materials of Zn, Al-Si intermediate alloy and Cu into a graphite crucible, putting the graphite crucible into a resistance furnace for smelting, and introducing argon as protective gas;

after the set time of smelting, putting Mg into a crucible to be continuously smelted until alloy molten slurry is formed;

and pouring the alloy molten slurry in the crucible into a mold for cooling to obtain the light high-entropy alloy cast ingot.

The component Si is added by taking Al-Si intermediate alloy as a raw material to reduce the smelting temperature, thereby achieving the purposes of reducing the loss of low-melting-point metal and saving energy consumption.

Furthermore, the raw materials of Zn, Al-Si intermediate alloy and Cu are sequentially Zn, Al-Si intermediate alloy and Cu from bottom to top in the crucible, and the smelting method can reduce the burning loss of low-melting-point elements.

Furthermore, the smelting temperature of the Zn, the Al-Si master alloy and the Cu is 750 ℃ and ~ 780 ℃ respectively.

Further, the smelting temperature of the Mg is 680 ℃ and ~ 700 ℃.

Further, the alloy molten slurry in the crucible is poured into a mold for cooling, and then repeatedly remelted for 3 times to obtain a light high-entropy alloy cast ingot, wherein the remelting temperature is set to be 720 ℃ and ~ 750 ℃ at 750 ℃.

Furthermore, the purity of the raw materials Al, Mg, Zn, Cu and Al-Si intermediate alloy block is more than 99.9 percent.

And further, cooling is carried out after the final remelting, and the cooling method adopts air cooling for 10 ~ 15 seconds and then water cooling to the set temperature, so that the cooling method improves the ingot casting crystallization speed, refines crystal grains and reduces casting defects.

Furthermore, the smelting temperature of the Zn, Al-Si intermediate alloy and Cu is 750 ℃ and ~ 780 ℃ and the smelting time is 20 ~ 30 minutes, the smelting temperature of the Mg is 680 ℃ and ~ 700 ℃ and the smelting time is 20 ~ 30 minutes, the Zn, Al-Si intermediate alloy and Cu are firstly smelted at a higher temperature, and the Mg is added at a lower temperature, so that the smelting method can reduce the burning loss of the Mg.

Furthermore, the atomic percentages of the elements Al, Mg, Zn, Cu and Si in the raw materials are 34 percent of Al ~ 36 percent, 15 percent of Mg ~ 25 percent, 29 percent of Zn ~ 31 percent, 4 percent of Cu ~ 6 percent and 5 percent of Si ~ 15 percent.

The beneficial effects produced by the invention comprise:

1. al, Mg, Zn, Cu and Si are common elements, the cost is not high, and the melting point is relatively low. Wherein Al, Mg and Zn are used as light metal elements and widely applied to the fields of aerospace and transportation, and have the advantages of light weight and excellent mechanical propertyDifferent advantages and the like. Although Si is not a metal element, the density of Si is low, and Si can also form silicide with other metal elements and disperse in the alloy structure to generate dispersion strengthening, so that the strength, the hardness and the wear resistance of the alloy are improved. The density of Cu is higher than that of other elements, but the atomic radius of Cu is slightly different from that of other elements, so that a solid solution structure is easily formed. The high-entropy alloy with the components has low cost and small density (3.8 g/cm)³) High compression strength (more than 750 Mpa) and strong corrosion resistance, and is suitable for the fields of aerospace, transportation and the like.

2. In the existing high-entropy alloy forming technology, the electric arc melting power is large, the burning loss is easy, the induction melting cost is high, the energy consumption is high, the requirement of mechanical alloying on raw materials is high, the alloy size is limited by a die, and the large-scale production of the low-melting-point light high-entropy alloy is difficult on the premise of low cost. The resistance furnace has the advantages of simple operation, easy control of smelting temperature and low equipment cost. The invention improves the process on the basis of the traditional resistance melting, and prepares the large-size light high-entropy alloy block with larger component melting point difference by using simple equipment and lower cost through methods of reducing the melting point by using the intermediate alloy, separately melting easily-burnt components and other components at different temperatures, finally cooling and forming by air cooling and water cooling, and the like.

Drawings

FIG. 1 shows Al in example 1 of the present invention₃₅Mg₁₅Zn₃₀Cu₅Si₁₅The optical microscopic structure of (1);

FIG. 2 shows Al in example 1 of the present invention₃₅Mg₁₅Zn₃₀Cu₅Si₁₅Compressive stress strain curve of (a).

FIG. 3 shows Al in example 1 of the present invention₃₅Mg₁₅Zn₃₀Cu₅Si₁₅And Al in example 3₃₅Mg₂₅Zn₃₀Cu₅Si₅Potentiodynamic polarization profiles in 3.5% NaCl aqueous solution.

Detailed Description

The preferred embodiment alloys of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more readily understood by those skilled in the art, and thus the scope of the present invention will be more clearly and clearly defined.

Examples 1

The light high-entropy alloy of the embodiment is Al₃₅Mg₁₅Zn₃₀Cu₅Si₁₅Using bulk Al, Mg, Zn, Cu and Al-Si intermediate alloy with the purity of more than 99.9 percent as raw materials, polishing the surface of the bulk raw materials by using sand paper, removing surface oxides, ultrasonically cleaning in alcohol, and drying for later use;

weighing the pretreated block raw material according to the molar ratio of the Al element to the Mg element to the Zn element to the Cu element to the Si element of 7:3:6:1:3, and preparing the raw material, wherein 10% more Mg is added when the raw material is prepared according to the molar ratio, because the Mg is easy to burn;

preparing a release agent according to the mass ratio of sodium silicate to zinc oxide to water of 1:3:6, coating the release agent on the surfaces of a graphite crucible and a stainless steel mold, and drying in a blast drying oven for more than 30 minutes for later use;

the prepared Zn, Al-Si intermediate alloy and Cu are sequentially placed into a graphite crucible, and the placing method can reduce the burning loss of low-melting-point elements. When the temperature of the resistance furnace rises to 780 ℃, putting the graphite crucible into the furnace to start smelting, and simultaneously introducing argon as protective gas;

after smelting at 780 ℃ for 30 minutes, setting the temperature of the resistance furnace to be 680 ℃, putting the prepared Mg block into a crucible to continue smelting when the temperature is reduced to 680 ℃, preserving the temperature at 680 ℃ for 30 minutes, stirring by using a stirring rod and removing scum on the surface;

and pouring the alloy solution in the crucible into a stainless steel mold for cooling, repeatedly remelting for 3 times, setting the remelting temperature to 750 ℃, and cooling by air cooling for 15 seconds in the cooling method during the final remelting to finally obtain the light high-entropy alloy ingot.

In this example, the microstructure of the light-weight high-entropy alloy in the as-cast state (as shown in fig. 1) was observed by an optical microscope, and the as-cast crystal grains were uniformly distributed, wherein the black part was the second phase formed by Si and Mg, and the mechanical property of the alloyCan play a role in strengthening. The density of the alloy is only 3.8g/cm³Is far lower than the traditional high-entropy alloy taking Al, Fe, Co, Cr, Mn and other elements as composition components. The compression performance of the alloy at room temperature in the as-cast state is tested by using an Shimadzu ZUAG-I250KV electronic tensile testing machine (shown in figure 2), and the compression strength at room temperature can reach 760 MPa. Testing the corrosion resistance of the alloy in an as-cast state by using CHI660E electrochemical workstation to obtain a potentiodynamic polarization curve (shown in figure 3), wherein the self-corrosion potential is-1.1 v at room temperature, and the self-corrosion current density is 6.02 multiplied by 10^-6A/cm²And the corrosion resistance is better.