阅读说明：本技术 一种高熵合金纳米复合材料及其制备方法 (High-entropy alloy nano composite material and preparation method thereof ) 是由 韩冰 毕贵军 郭震 陈立佳 张理 卢隆星 于 2020-12-30 设计创作，主要内容包括：本发明提供了一种高熵合金纳米复合材料及其制备方法,所述高熵合金纳米复合材料的制备方法包括如下步骤：混合反应工序,将石墨烯、金属盐前驱体和研磨球混合并反应,制备表面附着有石墨烯和纳米金属颗粒的研磨球；机械球磨工序,将所述表面附着有石墨烯和纳米金属颗粒的研磨球与高熵合金进行机械球磨,制备含石墨烯、纳米金属颗粒和高熵合金的复合粉末；增材制造工序,利用激光对所述复合粉末进行加热熔化,经沉积凝固,得到高熵合金纳米复合材料。本发明不仅能有效解决石墨烯和纳米金属颗粒的团聚问题,能够细化晶粒并改善高熵合金的晶界组织及力学性能,且该方法还能制备大尺寸、复杂结构且成分均匀的高熵合金基纳米复合材料零件。(The invention provides a high-entropy alloy nano composite material and a preparation method thereof, wherein the preparation method of the high-entropy alloy nano composite material comprises the following steps: a mixing reaction step, namely mixing and reacting graphene, a metal salt precursor and grinding balls to prepare the grinding balls with the surfaces attached with the graphene and nano metal particles; a mechanical ball milling step, namely performing mechanical ball milling on the grinding balls with the surfaces attached with the graphene and the nano metal particles and the high-entropy alloy to prepare composite powder containing the graphene, the nano metal particles and the high-entropy alloy; and in the additive manufacturing process, the composite powder is heated and melted by laser, and the high-entropy alloy nano composite material is obtained through deposition and solidification. The method can effectively solve the problem of agglomeration of the graphene and the nano metal particles, refine crystal grains, improve the grain boundary structure and mechanical properties of the high-entropy alloy, and prepare the high-entropy alloy-based nano composite material part with large size, complex structure and uniform components.)

1. A preparation method of a high-entropy alloy nanocomposite is characterized by comprising the following steps:

a mixing reaction step, namely mixing and reacting graphene, a metal salt precursor and grinding balls to prepare the grinding balls with the surfaces attached with the graphene and nano metal particles;

a mechanical ball milling step, namely performing mechanical ball milling on the grinding balls with the surfaces attached with the graphene and the nano metal particles and the high-entropy alloy to prepare composite powder containing the graphene, the nano metal particles and the high-entropy alloy;

and in the additive manufacturing process, the composite powder is heated and melted by laser, and the high-entropy alloy nano composite material is obtained through deposition and solidification.

2. A method of producing a high entropy alloy nanocomposite according to claim 1, wherein the mixing reaction process includes: mixing the graphene, the metal salt precursor and the grinding balls to form a suspension, performing ultrasonic dispersion and drying on the suspension to obtain the grinding balls with the graphene and the metal salt precursor attached to the surfaces, and performing reduction reaction on the grinding balls with the graphene and the metal salt precursor attached to the surfaces under the protection of inert gas to obtain the grinding balls with the graphene and the nano metal particles attached to the surfaces.

3. A method for preparing a high-entropy alloy nanocomposite material according to claim 1 or 2, wherein a mass ratio of the total mass of the graphene and the metal salt precursor to the grinding balls is 1: 50-500, wherein the mass ratio of the graphene to the metal salt precursor is 1: 1-150.

4. A method of preparing a high entropy alloy nanocomposite material according to claim 1,

the metal salt precursor is an organic metal salt precursor, and the organic metal salt precursor contains C₁₀H₁₄NiO₄、C₁₅H₂₁CoO₆、C₂₀H₂₈ZrO₈、C₁₅H₂₁ScO₆、C₁₅H₂₃CeO₇、C₁₅H₂₁ErO₆And C₁₅H₂₄O₆At least two of Y;

the graphene is reduced graphene with the purity of more than 99%, and the number of layers of the graphene is not more than five;

the grinding balls are hard alloy grinding balls and/or ceramic grinding balls, and the diameters of the grinding balls are at least two of 15mm, 12mm, 10mm, 8mm and 5 mm.

5. A method for preparing a high-entropy alloy nanocomposite material as claimed in claim 2, wherein the frequency of ultrasonic dispersion is 10 to 30kHZ, and the time of ultrasonic dispersion is 60 to 420 min.

6. A method of producing a high entropy alloy nanocomposite according to claim 2, wherein the reduction reaction includes: under the protection of inert gas, the grinding ball with the graphene and the metal salt precursor attached to the surface is heated to the reduction reaction temperature from the normal temperature, the temperature is kept for 30-240min, wherein the reduction reaction temperature is 350-900 ℃, the heating rate is 50-200 ℃/min, and the inert gas is argon with the purity not lower than 99.9%.

7. A method for preparing a high-entropy alloy nanocomposite material according to claim 1, wherein the mass ratio of the grinding balls with the graphene and the nano-metal particles attached to the surfaces thereof to the high-entropy alloy is 10-30: 1.

8. a method of producing a high entropy alloy nanocomposite according to claim 1 or 7, wherein the high entropy alloy includes at least four of Co, Cr, Ti, Ni, Fe, Mn, Zr and Al elements, wherein the molar ratio of each element is Co: cr: ti: ni: fe: mn: zr: al is 0-35: 0-35: 0-35: 0-35: 0-25: 0-25: 0-35: 0-15.

9. A method of producing a high entropy alloy nanocomposite according to claim 1, wherein the additive manufacturing process includes: the laser heats and melts the composite powder, and the high-entropy alloy nano composite material is formed by deposition and solidification in the range of laser power of 300-: the scanning speed is 0.2-2.0m/min, the powder feeding speed is 1.0-10.0g/min, the overlapping rate is 20-60%, the diameter of a light spot is 1.0-4.0mm, the defocusing amount is 5.0-25.0mm, the layer height is 0.2-1.0mm, the protective gas is argon with the purity of more than 99.5%, and the flow of the protective gas is 5-25L/min.

10. A high-entropy alloy nanocomposite, characterized in that the high-entropy alloy nanocomposite is produced by the method for producing a high-entropy alloy nanocomposite according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of composite materials, in particular to a high-entropy alloy nano composite material and a preparation method thereof.

Background

The high-entropy alloy generally refers to a brand-new multi-element alloy system which is composed of 4 to 13 main elements in an atomic ratio or a nearly equal atomic ratio and has a simple solid solution structure. Compared with the traditional alloy, the high-entropy alloy has the advantages of high entropy effect, slow diffusion effect, serious lattice distortion effect and cocktail effect, and the characteristics enable the high-entropy alloy to have excellent performance and huge potential application value in the aspects of hardness, compressive strength, thermal stability, corrosion resistance, magnetic performance, oxidation resistance and the like.

In order to further improve the mechanical properties and microstructure of the high-entropy alloy, researchers try to form the high-entropy alloy nanocomposite by using the high-entropy alloy as a matrix and one or more nanoscale metal or nonmetal particles as reinforcements. Compared with the traditional high-entropy alloy composite material, the high-entropy alloy composite material has stronger interface bonding force, higher specific strength, specific modulus, hardness, wear resistance and other characteristics. The high-entropy alloy nano composite material is mainly prepared by using the traditional methods of casting, powder metallurgy, in-situ synthesis and the like, but the difficult problem of large agglomeration tendency of nano particles exists, and the dispersion distribution of the nano particles is difficult to realize. In addition, the high-entropy alloy nanocomposite has large deformation resistance, so that the subsequent mechanical material reduction difficulty is higher, and the manufacture of large-size high-entropy alloy nanocomposite parts with complex structures is difficult, thereby becoming a bottleneck problem restricting the application of the high-entropy alloy nanocomposite parts in key industrial fields such as aerospace, marine engineering of ships, low-temperature gas storage and the like.

Disclosure of Invention

The invention aims to solve the problem that the high-entropy alloy nanocomposite has a large tendency of nanoparticle agglomeration, so that the structure and the performance of the high-entropy alloy nanocomposite are influenced.

In order to solve the problems, the invention provides a preparation method of a high-entropy alloy nano composite material, which comprises the following steps:

a mixing reaction step, namely mixing and reacting graphene, a metal salt precursor and grinding balls to prepare the grinding balls with the surfaces attached with the graphene and nano metal particles;

a mechanical ball milling step, namely performing mechanical ball milling on the grinding balls with the surfaces attached with the graphene and the nano metal particles and the high-entropy alloy to prepare composite powder containing the graphene, the nano metal particles and the high-entropy alloy;

and in the additive manufacturing process, the composite powder is heated and melted by laser, and the high-entropy alloy nano composite material is obtained through deposition and solidification.

Preferably, the mixing reaction process comprises: mixing the graphene, the metal salt precursor and the grinding balls to form a suspension, performing ultrasonic dispersion and drying on the suspension to obtain the grinding balls with the graphene and the metal salt precursor attached to the surfaces, and performing reduction reaction on the grinding balls with the graphene and the metal salt precursor attached to the surfaces under the protection of inert gas to obtain the grinding balls with the graphene and the nano metal particles attached to the surfaces.

Preferably, the mass ratio of the total mass of the graphene and the metal salt precursor to the grinding ball is 1: 50-500, wherein the mass ratio of the graphene to the metal salt precursor is 1: 1-150.

Preferably, the metal salt precursor is an organometallic salt precursor, and the organometallic salt isThe precursor contains C₁₀H₁₄NiO₄、C₁₅H₂₁CoO₆、C₂₀H₂₈ZrO₈、C₁₅H₂₁ScO₆、C₁₅H₂₃CeO₇、C₁₅H₂₁ErO₆And C₁₅H₂₄O₆At least two of Y;

preferably, the graphene is reduced graphene with the purity of more than 99%, and the number of layers of the graphene is not more than five;

preferably, the grinding balls are cemented carbide grinding balls and/or ceramic grinding balls, and the diameters of the grinding balls are at least two of 15mm, 12mm, 10mm, 8mm and 5 mm.

Preferably, the frequency of ultrasonic dispersion is 10-30kHZ, and the time of ultrasonic dispersion is 60-420 min.

Preferably, the reduction reaction comprises: under the protection of inert gas, the grinding ball with the graphene and the metal salt precursor attached to the surface is heated to the reduction reaction temperature from the normal temperature, the temperature is kept for 30-240min, wherein the reduction reaction temperature is 350-900 ℃, the heating rate is 50-200 ℃/min, and the inert gas is argon with the purity not lower than 99.9%.

Preferably, the mass ratio of the grinding balls with the graphene and the nano metal particles attached to the surfaces to the high-entropy alloy is 10-30: 1.

preferably, the high-entropy alloy comprises at least four elements of Co, Cr, Ti, Ni, Fe, Mn, Zr and Al, wherein the molar ratio of each element is Co: cr: ti: ni: fe: mn: zr: al is 0-35: 0-35: 0-35: 0-35: 0-25: 0-25: 0-35: 0-15.

Preferably, the additive manufacturing process comprises: the laser heats and melts the composite powder, and the high-entropy alloy nano composite material is formed by deposition and solidification in the range of laser power of 300-: the scanning speed is 0.2-2.0m/min, the powder feeding speed is 1.0-10.0g/min, the overlapping rate is 20-60%, the diameter of a light spot is 1.0-4.0mm, the defocusing amount is 5.0-25.0mm, the layer height is 0.2-1.0mm, the protective gas is argon with the purity of more than 99.5%, and the flow of the protective gas is 5-25L/min.

Compared with the prior art, the preparation method of the high-entropy alloy nano composite material has the following beneficial effects:

1. the invention takes the grinding balls as carriers of the graphene and the metal salt precursor, takes the graphene as the carrier of the metal salt precursor, the metal salt precursor is subjected to reduction reaction under the action of the graphene to generate nano metal particles, the nano metal particles uniformly grow on the surface of the lamellar graphene, the graphene and the nano metal particles are combined through chemical action, the graphene and the metal salt precursor are combined with the grinding balls through van der Waals force, the graphene and the nano metal particle structure are attached to the surface of the grinding balls through van der Waals force after the reaction, the graphene and the nano metal particle structure are generated on the surface of the grinding balls in advance, the agglomeration problem of the graphene and the nano metal particles in the mechanical ball milling is effectively solved, and the phenomenon that the graphene and the nano metal particles are agglomerated on the grinding balls in the mechanical ball milling process is also effectively avoided, the grinding balls with the graphene and the nano metal particles attached to the surfaces are closely combined with the high-entropy alloy powder through collision under the action of mechanical force through mechanical ball milling to prepare uniformly distributed composite powder of the graphene, the nano metal particles and the high-entropy alloy, and finally the composite powder of the graphene, the nano metal particles and the high-entropy alloy is prepared into the high-entropy alloy composite material through a laser-assisted additive manufacturing technology, so that the efficiency of preparing the high-entropy alloy composite material is improved, the utilization rate of raw materials is improved, the manufacturing cost of the high-entropy alloy composite material is reduced, the generation of intercrystalline cracks on a large-size structural member can be effectively inhibited, and the preparation of a high-entropy alloy nano composite material part with a large size, a complex structure and uniform components can be realized through the laser additive manufacturing technology;

2. the invention takes the high-entropy alloy as a substrate, takes the graphene and the nano metal particles as a reinforcement, takes the grinding balls as a macroscopic carrier of the graphene, takes the graphene as a microscopic carrier of the nano metal particles, and distributes the nano metal particles among the sheet layers of the graphene, thereby not only effectively avoiding the agglomeration problem of the graphene and the nano metal particles, but also changing the microstructure of the graphene, realizing more flexible and precise regulation and control on the performance of the high-entropy alloy, and reducing the using amount of the graphene on the premise of ensuring that the high-entropy alloy nanocomposite material has better mechanical property, thereby reducing the production cost of the high-entropy alloy nanocomposite material, realizing grain refinement, grain boundary refinement and performance improvement of the high-entropy alloy through the synergistic effect between the graphene and the nano metal particles, and further improving the reinforcement promotion effect of the reinforcement on the high-entropy alloy, the mechanical property of the high-entropy alloy composite material is improved.

The invention also provides a high-entropy alloy nano composite material, which is prepared by adopting the preparation method of the high-entropy alloy nano composite material.

Compared with the prior art, the high-entropy alloy nanocomposite provided by the invention has the same beneficial effects as the preparation method of the high-entropy alloy nanocomposite provided by the invention has, and the detailed description is omitted.

Drawings

FIG. 1 is a flow chart of the preparation of a high-entropy alloy nanocomposite according to an embodiment of the invention;

fig. 2 is an SEM image at 50000 times of a composite powder of graphene, nano ErY metal particles and CrFeCoNi in example 1 of the present invention;

fig. 3 is a graph of EDS results at 50000 times for composite powder of graphene, nano ErY metal particles and CrFeCoNi in example 1 of the present invention;

FIG. 4 is an SEM image of a CrFeCoNi-based nanocomposite material at 3000 times in example 1 of the present invention;

fig. 5 is an SEM image of the composite powder of graphene, nano ZrErYCoNi metal particles, and CrFeCoNi at 40000 times in example 2 of the present invention;

fig. 6 is a graph of EDS results at 40000 times for the composite powder of graphene, nano ZrErYCoNi metal particles, and CrFeCoNi in example 2 of the present invention;

FIG. 7 is an SEM image of a CrFeCoNi-based nanocomposite material at 3000 times in example 2 of the present invention;

FIG. 8 is an SEM image of a CrFeCoNi high-entropy alloy of comparative example 1 of the present invention at 6000 times.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In addition, the terms "comprising," "including," "containing," and "having" are intended to be non-limiting, i.e., that other steps and other ingredients can be added that do not affect the results. Materials, equipment and reagents are commercially available unless otherwise specified.

In addition, although the invention has described the forms of S1, S2, S3 and the like for each step in the preparation, the description is only for the convenience of understanding, and the forms of S1, S2, S3 and the like do not represent the limitation of the sequence of each step.

Graphene has excellent tensile, optical, heat-conducting and electric-conducting properties, has become an ideal reinforcement of a metal-based composite material, and has been widely researched in application of the graphene in Cu, Al, Ni and Mg-based composite materials, while few researches on application of the graphene in refractory alloys such as high-entropy/medium-entropy alloys are currently carried out, and the main reason is that nano-scale graphene is easy to agglomerate, and the agglomeration tendency of the nano-scale graphene is a main problem restricting the application of the graphene in the high-entropy alloy composite materials. Although the graphene reinforced high-entropy alloy composite material is disclosed in the prior art, only the traditional mechanical ball milling method is adopted to prepare the graphene high-entropy alloy mixed powder, the traditional mechanical ball milling method cannot solve the problem of agglomeration of the nano-scale graphene, and cannot avoid adverse effects of the agglomeration of the nano-scale graphene on the matrix structure and performance of the high-entropy alloy. In addition, in the prior art, the high-entropy alloy composite material is mainly prepared by adopting a spark plasma sintering technology, a special graphite die is needed to synthesize a small block material with a simple shape, the near-net forming of the high-entropy alloy composite material is difficult to realize, the subsequent mechanical material reduction difficulty is increased, the large-size high-entropy alloy nano composite material part with a complex structure is difficult to manufacture, and the application of the high-entropy alloy composite material in the key industrial fields of aerospace, marine engineering of ships, low-temperature gas storage and the like is restricted.

In order to solve the problems, the invention provides a high-entropy alloy nano composite material and a preparation method thereof, wherein a high-entropy alloy is used as a matrix, graphene and nano metal particles are used as reinforcements, a graphene and nano metal particle structure is generated on the surface of a grinding ball in advance through ultrasonic dispersion and reduction reaction, composite powder of uniformly distributed graphene, nano metal particles and high-entropy alloy is prepared through mechanical ball milling, finally the composite powder of uniformly distributed graphene, nano metal particles and high-entropy alloy is prepared into the high-entropy alloy composite material through a laser-assisted additive manufacturing technology, the agglomeration phenomenon of the graphene and the nano metal particles in the mechanical ball milling process can be effectively avoided, the grain boundary structure and the mechanical property of the high-entropy alloy composite material are improved, and the high-entropy alloy composite material prepared through the laser-assisted additive manufacturing technology can also be used for preparing large-size high-entropy alloy composite materials, High-entropy alloy-based nanocomposite part with a complex structure and uniform components.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 1, an embodiment of the present invention provides a method for preparing a high-entropy alloy nanocomposite, including the following steps:

a mixing reaction step, namely mixing and reacting graphene, a metal salt precursor and grinding balls to prepare the grinding balls with the surfaces attached with the graphene and nano metal particles;

a mechanical ball milling process, namely performing mechanical ball milling on the grinding balls with the surfaces attached with the graphene and the nano metal particles and the high-entropy alloy to prepare composite powder containing the graphene, the nano metal particles and the high-entropy alloy;

and in the additive manufacturing process, the composite powder is heated and melted by laser, and the high-entropy alloy nano composite material is obtained through deposition and solidification.

By taking the grinding balls as carriers of the graphene and the metal salt precursor and taking the graphene as the carrier of the metal salt precursor, the metal salt precursor is subjected to a reduction reaction under the action of the graphene to generate nano metal particles, the nano metal particles are uniformly grown on the surface of the lamellar graphene, the graphene and the nano metal particles are combined through chemical action, and the graphene and the metal salt precursor are combined with the grinding ball through Van der Waals force, the graphene and the nano metal particle structure are attached to the surface of the grinding ball through Van der Waals force after reaction, by generating the graphene and nano metal particle structures on the surfaces of the grinding balls in advance, the reaction area can be increased, the generation quality and efficiency of nano metal particles are improved, the agglomeration problem of the graphene and the nano metal particles in mechanical ball milling is effectively solved, and the phenomenon that the graphene and the nano metal particles are agglomerated on the grinding balls in the mechanical ball milling process is also avoided; then, by mechanical ball milling, the grinding balls with the graphene and the nano metal particles attached to the surfaces and the high-entropy alloy powder are combined through collision under the action of mechanical force, so that the graphene, the nano metal particles and the high-entropy alloy are combined more tightly and firmly, and composite powder of the graphene, the nano metal particles and the high-entropy alloy which are uniformly distributed is prepared; finally, the high-entropy alloy composite material is prepared from the composite powder of the graphene, the nano metal particles and the high-entropy alloy through a laser-assisted additive manufacturing technology, so that the efficiency of preparing the high-entropy alloy composite material is improved, the utilization rate of raw materials is improved, the manufacturing cost of the high-entropy alloy composite material is reduced, the generation of intergranular cracks on a large-size structural member can be effectively inhibited, the preparation of high-entropy alloy nano composite material parts with large sizes, complex structures and uniform components can be realized through the laser additive manufacturing technology, and the near-net forming of the high-entropy alloy composite material is realized. According to the preparation method of the high-entropy alloy nanocomposite, the grinding balls are used as a macroscopic carrier of the graphene, the graphene is used as a microscopic carrier of the nano metal particles, the agglomeration phenomenon of the nano metal particles and the graphene can be effectively avoided, the microstructure of the graphene can be changed by the nano metal particles, the performance of the high-entropy alloy can be regulated and controlled more flexibly and accurately, the using amount of the graphene can be reduced on the premise that the high-entropy alloy nanocomposite has better mechanical properties, so that the production cost of the high-entropy alloy nanocomposite is reduced, the grain refinement, the grain boundary refinement and the performance (including microhardness, frictional wear performance and the like) of the high-entropy alloy can be improved through the synergistic effect of the graphene and the nano metal particles, and the method can also be used for preparing large-size, large-size and high-entropy alloy, High-entropy alloy-based nanocomposite part with a complex structure and uniform components.

Specifically, the mixed reaction process comprises the following steps: mixing graphene, a metal salt precursor and grinding balls to form a suspension, performing ultrasonic dispersion and drying on the suspension to obtain the grinding balls with the graphene and the metal salt precursor attached to the surfaces, and performing reduction reaction on the grinding balls with the graphene and the metal salt precursor attached to the surfaces under the protection of inert gas to obtain the grinding balls with the graphene and the nano metal particles attached to the surfaces.

Wherein the mass ratio of the total mass of the graphene and the metal salt precursor to the grinding balls is 1: 50-500, wherein the mass ratio of the graphene to the metal salt precursor is 1: 1-150. By limiting the addition of the graphene, the metal salt precursor and the grinding balls within a certain range, the refining effect of the nano metal particles on crystal grains and the improvement of the graphene on the performance of crystal boundaries can be fully exerted, and the lamellar graphene is mixed with the powdery metal salt precursor, the graphene loads the metal salt precursor, the metal salt precursor is distributed among the lamellar of the graphene, through the relation between the loading and the loaded, the problems caused by the agglomeration of the graphene and the nano metal particles can be effectively counteracted, the microstructure of the graphene can be changed, thereby further improving the refining effect on crystal grains, improving the grain boundary structure and improving the mechanical property, realizing the enhancement and promotion effect of the reinforcement on the high-entropy alloy, improving the mechanical property of the high-entropy alloy composite material, and preventing the adverse effect of the excessive reinforcement on the characteristics of the high-entropy alloy; the grinding balls can be fully loaded with graphene and nano metal particles, so that uniformly distributed composite powder of graphene, nano metal particles and high-entropy alloy can be obtained subsequently, and waste of raw materials caused by excessive amount of graphene and nano metal particles can be avoided.

In the present embodiment, the metal salt precursor is an organic metal salt precursor, and more specifically, the organic metal salt precursor contains C₁₀H₁₄NiO₄、C₁₅H₂₁CoO₆、C₂₀H₂₈ZrO₈、C₁₅H₂₁ScO₆、C₁₅H₂₃CeO₇、C₁₅H₂₁ErO₆And C₁₅H₂₄O₆At least two of Y, that is, the organic metal salt precursor may be an organic rare earth metal salt precursor, an organic non-rare earth metal salt precursor, or an organic rare earth metal salt precursor and an organic non-rare earth metal salt precursor, and when the organic metal salt precursor is only an organic rare earth metal salt precursor or only an organic non-rare earth metal salt precursor, the substances in the organic metal salt precursor may be mixed in any molar ratio, which is not particularly limited in the present invention, and for example, the molar ratio may be 1: 1, or a mixture of 1: 1: 1 mixing and the like; when the organic metal salt precursor is an organic rare earth metal salt precursor and an organic non-rare earth metal salt precursor, the molar ratio of the organic non-rare earth metal salt precursor to the organic rare earth metal salt precursor is 1: 1-5.

In the present embodiment, the metal salt precursor is in a powder form, and the particle size of the metal salt precursor in the powder form is not particularly limited. In some alternative embodiments, the particle size of the metal salt precursor may be 20-200nm, such as 50nm, 80nm, 180nm, and the like. Therefore, the particle size of the metal salt precursor is controlled within a certain range, so that the metal salt precursor can be distributed among the graphene sheets, the reinforcement and the high-entropy alloy matrix can be mixed more fully, and the compatibility among the reinforcement, the high-entropy alloy matrix and the high-entropy alloy matrix is enhanced.

In this embodiment, the graphene is in a lamellar shape, the lamellar graphene is reduced graphene having a purity of 99% or more, and the number of layers of the reduced graphene does not exceed five. In some preferred embodiments, the graphene is a multi-layer reduced graphene having a purity of not less than 99.5%, and the number of layers of the multi-layer reduced graphene is two to five. By optimizing the purity and the number of layers of the graphene, the high-entropy alloy can be enhanced and promoted more effectively, and a metal salt precursor can be loaded better, so that the performance of the prepared high-entropy alloy nanocomposite can be improved more effectively.

The microstructure of the surface of the grinding ball inevitably generates minute protrusions and depressions during machining of the grinding ball, thereby providing the surface of the grinding ball with defects, and graphene and metal salt precursors are captured or dropped therein by these surface defects during ultrasonic dispersion and are bonded to the grinding ball by van der waals force to be attached to the surface of the grinding ball. In the present embodiment, the grinding balls are hard alloy grinding balls and/or ceramic grinding balls, and more specifically, the grinding balls are one or a mixture of tungsten carbide grinding balls, corundum grinding balls, zirconia grinding balls, zirconium silicate grinding balls and agate grinding balls. The strength and the grinding effect of the hard alloy grinding balls and the ceramic grinding balls are superior to those of common alloy balls (such as stainless steel grinding balls), the phase transition point temperature of the hard alloy grinding balls and the ceramic grinding balls is higher than that of the common alloy balls, the hard alloy grinding balls and the ceramic grinding balls have better high-temperature resistance in the subsequent reaction process, still have higher hardness and strength at higher temperature, and do not influence the use in the subsequent mechanical ball grinding process and the repeated use of the grinding balls.

In this embodiment, the grinding balls have diameters of at least two of 15mm, 12mm, 10mm, 8mm and 5mm, and the mixing ratio of the grinding balls having different diameters is not particularly limited in this embodiment. In some alternative embodiments, if the grinding balls are grinding balls with two diameters, the number ratio of the grinding balls with larger diameter to the grinding balls with smaller diameter is 1: 1-10, for example: if the grinding balls are grinding balls with the diameters of 15mm and 10mm, the number ratio of the grinding balls with the diameters of 15mm to the grinding balls with the diameters of 10mm is 1: 5. in other alternative embodiments, if the grinding balls are grinding balls with three diameters, the number ratio of the grinding balls from the larger diameter to the smaller diameter is 1: 1-10: 1-15, for example: if the grinding balls are grinding balls with the diameters of 12mm, 10mm and 8mm, the number ratio of the grinding balls with the diameters of 12mm, 10mm and 8mm is 1: 1: 2.5. in other alternative embodiments, if the grinding balls are grinding balls with four diameters, the number ratio of the grinding balls from the larger diameter to the smaller diameter is 1: 1-10: 1-10: 1-15, for example: if the grinding balls are grinding balls with the diameters of 15mm, 10mm, 8mm and 5mm, the number ratio of the grinding balls with the diameters of 15mm, 10mm, 8mm and 5mm is 1: 2: 3: 5. in other alternative embodiments, if the grinding balls are grinding balls with five diameters, the number ratio of the grinding balls with the diameters of 15mm, 12mm, 10mm, 8mm and 5mm is 1: 1-10: 1-10: 1-10: 1-15, for example: the number ratio of the grinding balls with the diameters of 15mm, 12mm, 10mm, 8mm and 5mm is 1: 1: 3: 3: 5. therefore, at least two grinding balls with different diameters are selected to ensure that the grinding balls with the surfaces attached with the graphene and the nano metal particles and the high-entropy alloy can be fully mixed in the mechanical ball-milling process to prepare composite powder of the graphene, the nano metal particles and the high-entropy alloy which are uniformly distributed, and the nano metal particles and the high-entropy alloy can be more tightly and firmly combined.

In the present embodiment, the solvent and the amount thereof used for preparing the suspension of graphene, the metal salt precursor, and the milling ball in the mixing reaction process are not particularly limited. In some preferred embodiments, the solvent is absolute ethyl alcohol, and the volume ratio of the absolute ethyl alcohol to the grinding balls is 3-10: 1. the method selects the absolute ethyl alcohol as a medium, is easy to volatilize, and can more effectively and conveniently attach the graphene and the metal salt precursor to the surface of the grinding ball in the ultrasonic dispersion process.

In this example, the ultrasonic dispersion of the suspension was carried out at a frequency of 10 to 30kHZ and for a period of 60 to 420 min. In some preferred embodiments, the suspension is ultrasonically dispersed at a frequency of 15-25kHZ for 180-360 min. Therefore, the graphene and the metal salt precursor in the suspension can be uniformly coated on the surface of the grinding ball.

In this embodiment, after the suspension is ultrasonically dispersed, the grinding ball with the graphene and the metal salt precursor attached to the surface thereof is carefully taken out and dried to remove the trace amount of moisture remaining in the grinding ball. In some alternative embodiments, the drying temperature is 45-95 deg.C and the drying time is 60-600 min.

In this embodiment, under the protection of an inert gas, the temperature of the grinding ball with the graphene and the metal salt precursor attached to the surface is raised from normal temperature to the reduction reaction temperature, and the temperature is maintained for 30-240min, wherein the reduction reaction temperature is 350-. Therefore, the reduction reaction can be ensured to fully reduce the metal salt precursor into the nano metal particles.

In this embodiment, in the mechanical ball milling process, the mass ratio of the grinding balls with the graphene and the nano-metal particles attached to the surfaces to the high-entropy alloy is 10 to 30: 1. therefore, the mass ratio of the grinding balls with the graphene and the nano metal particles attached to the surfaces to the high-entropy alloy is limited within a certain range, so that the promotion effect of the reinforcement on the high-entropy alloy can be realized, the mechanical property of the high-entropy alloy nano composite material is improved, and the adverse effect of the excessive reinforcement on the characteristics of the high-entropy alloy can be prevented.

In the present embodiment, the high-entropy alloy includes at least four elements of Co, Cr, Ti, Ni, Fe, Mn, Zr, and Al, wherein the molar ratio of each element is Co: cr: ti: ni: fe: mn: zr: al is 0-35: 0-35: 0-35: 0-35: 0-25: 0-25: 0-35: 0-15.

In the present embodiment, the purity and particle size of each element powder in the high-entropy alloy are not particularly limited. In some alternative embodiments, the purity of each element powder in the high entropy alloy may be 99.5% or more. In other alternative embodiments, the high entropy alloy powder has a particle size of 45-95 μm. Therefore, the purity and the grain size of the high-entropy alloy matrix can be ensured to be within a certain range, and the mechanical property of the prepared high-entropy alloy nano composite material is improved.

In this embodiment, the grinding balls with the graphene and the nano-metal particles attached to the surfaces are mechanically ball-milled with the high-entropy alloy, the rotation speed of the mechanical ball-milling is 250-. Therefore, the composite powder of the graphene, the nano metal particles and the high-entropy alloy which are uniformly distributed can be prepared, and the graphene, the nano metal particles and the high-entropy alloy can be combined more tightly and firmly.

In this embodiment, after the mechanical ball milling process and before the additive manufacturing process, the method further includes performing size classification screening on the composite powder of graphene, nano-metal particles and the high-entropy alloy to obtain the composite powder with a particle size of 45-95 μm, so as to prepare the high-entropy alloy nanocomposite through the additive manufacturing process.

In this embodiment, the additive manufacturing process is a laser-assisted additive manufacturing process, that is, an LAAM process, and a specific process is not particularly limited, and those skilled in the art can adjust the process according to actual situations. The laser-assisted additive manufacturing process can be used for preparing the high-entropy alloy-based nanocomposite part with a large size, a complex structure and uniform components, the efficiency of preparing the high-entropy alloy-based nanocomposite is improved, intergranular cracks on a large-size structural member can be effectively inhibited through the process, so that the actual industrial application level is reached, in addition, the material utilization rate of the process is relatively high, and the manufacturing cost of the high-entropy alloy nanocomposite is more favorably reduced.

In this embodiment, the additive manufacturing process comprises: the composite powder is heated and melted by laser, and is deposited and solidified to form the high-entropy alloy nano composite material within the range of laser power of 300-2500W, wherein the laser can be generated through a processing platform (LAAM platform), and the optimization parameters of the processing platform are as follows: the scanning speed is 0.2-2.0m/min, the powder feeding speed is 1.0-10.0g/min, the overlapping rate is 20-60%, the diameter of a light spot is 1.0-4.0mm, the defocusing amount is 5.0-25.0mm, the layer height is 0.2-1.0mm, the protective gas is argon with the purity of more than 99.5%, and the flow of the protective gas is 5-25L/min. Therefore, the working stability of the processing platform can be ensured, and the additive manufacturing efficiency is improved.

The embodiment of the invention also provides a high-entropy alloy nano composite material, which is prepared by adopting the preparation method of the high-entropy alloy nano composite material.

In order to further illustrate the present invention, the following examples are given to further illustrate the present invention. The experimental methods used in the examples of the present invention are all conventional methods unless otherwise specified; materials, reagents and the like used in examples of the present invention are commercially available unless otherwise specified.

Example 1

The embodiment provides a high-entropy alloy nanocomposite, which takes CrFeCoNi as a matrix and takes graphene and nano ErY metal particles as reinforcements. The embodiment also provides a preparation method of the high-entropy alloy nanocomposite, which comprises the following steps:

1.1 selecting the multilayer reduced graphene with the purity of not less than 99.9 percent and the C with the purity of not less than 99.9 percent₁₅H₂₁ErO₆And C₁₅H₂₄O₆Y is metal salt precursor powder and tungsten carbide grinding balls are used as raw materials, and the mass of each raw material is accurately weighed by using an electronic balance, wherein C in the metal salt precursor₁₅H₂₁ErO₆And C₁₅H₂₄O₆The molar ratio of Y is 1: 1, the mass ratio of the multilayer reduced graphene to the metal salt precursor powder is 1: 50, the mass ratio of the total mass of the multilayer reduced graphene and the metal salt precursor powder to the tungsten carbide grinding balls is 1: 200, the tungsten carbide grinding balls are 12mm, 10mm and 8mm in diameter, and the quantity ratio of the 12mm, 10mm and 8mm tungsten carbide grinding balls is 2 in sequence: 2: 5; accurately weighing absolute ethyl alcohol by using a measuring cylinder and a beaker, wherein the volume ratio of the absolute ethyl alcohol to the tungsten carbide grinding balls is 8: 1, measuring absolute ethyl alcohol; pouring the weighed multilayer reduced graphene, the metal salt precursor powder, the tungsten carbide grinding balls and the absolute ethyl alcohol into a beaker together, and stirring and mixing uniformly to form a suspension;

1.2 carrying out ultrasonic dispersion treatment on the suspension obtained in the step 1.1, inserting an amplitude transformer of an ultrasonic disperser into a position 30mm below the liquid level of the suspension, carrying out ultrasonic dispersion treatment at the ultrasonic dispersion frequency of 20kHz for 300min, volatilizing most of absolute ethyl alcohol in the suspension to obtain the suspension with graphite uniformly attached to the surfaceAlkene, C₁₅H₂₁ErO₆And C₁₅H₂₄O₆Taking out the tungsten carbide grinding balls carefully, placing the tungsten carbide grinding balls into a dry beaker, placing the beaker into a drying oven, and drying at the drying temperature of 85 ℃ for 240min to remove graphene and C uniformly adhered to the surface₁₅H₂₁ErO₆And C₁₅H₂₄O₆Residual moisture in the tungsten carbide grinding balls of Y;

1.3 graphene and C are uniformly adhered to the surface obtained in the step 1.2₁₅H₂₁ErO₆And C₁₅H₂₄O₆Putting the Y tungsten carbide grinding ball into a heat treatment furnace, introducing argon with the purity of 99.9 percent into the heat treatment furnace as protective gas, and then uniformly attaching graphene and C on the surface at the heating rate of 100 ℃/min₁₅H₂₁ErO₆And C₁₅H₂₄O₆Heating the tungsten carbide grinding balls of the Y from normal temperature to 700 ℃ for reduction reaction, preserving heat for 180min, and naturally cooling to normal temperature along with the furnace to obtain the tungsten carbide grinding balls with the surfaces attached with graphene and nanometer ErY metal particles;

1.4 selecting CrFeCoNi high-entropy alloy powder as a matrix, wherein the purity of each element in the high-entropy alloy powder is not lower than 99.5%, the particle size of the high-entropy alloy powder is 45-95 μm, and the mass ratio of tungsten carbide grinding balls with graphene and nanometer ErY metal particles attached to the surfaces to the CrFeCoNi high-entropy alloy powder is 20: 1, accurately weighing CrFeCoNi high-entropy alloy powder by using an electronic balance, adding tungsten carbide grinding balls with graphene and nano ErY metal particles attached to the surfaces and the CrFeCoNi high-entropy alloy powder into a hard alloy ball-milling tank, and carrying out ball-milling for 300min at the rotating speed of 450r/min to obtain composite powder of the graphene, the nano ErY metal particles and the CrFeCoNi;

1.5 screening the composite powder of graphene, nano ErY metal particles and CrFeCoNi obtained in step 1.4 by using a mechanical powder sifter to obtain composite powder with the particle size of 45-95 μm, putting the screened composite powder into a powder feeder powder cylinder of LAAM equipment, setting the laser power to be 800W, the scanning rate to be 0.6m/min, the powder feeding rate to be 8.3g/min, the overlapping rate to be 50%, the spot diameter to be 2.5mm, the defocusing amount to be 15.0mm, the layer height to be 0.4mm, the shielding gas to be argon with the purity of 99.99%, the shielding gas flow to be 20L/min, and carrying out laser-assisted additive manufacturing to obtain the CrFeCoNi-based nano composite material, wherein the size of the CrFeCoNi-based nano composite material is 100mm multiplied by 70mm by 5 mm.

Analyzing the composite powder of graphene, nano ErY metal particles and CrFeCoNi and the CrFeCoNi-based nanocomposite material prepared in this example, obtaining the result graphs shown in fig. 2-4, where fig. 2 is an SEM (scanning electron microscope) microscopic morphology graph of the composite powder of graphene, nano ErY metal particles and CrFeCoNi at 50000 times; fig. 3 is a graph showing EDS (energy spectrum analysis) results of composite powder of graphene, nano ErY metal particles and CrFeCoNi; FIG. 4 is an SEM micrograph of CrFeCoNi-based nanocomposites at 3000 times. As can be seen from fig. 2, the particle size of the nano ErY metal particles prepared by the method of this embodiment is 10-150nm, the shape of the nano ErY metal particles is more regular and uniformly generated on the surface of graphene, and the graphene is uniformly attached to the surface of CrFeCoNi. As can be seen from fig. 4, the CrFeCoNi-based nanocomposite prepared by the method of the present embodiment has fine crystal grains, a fine equiaxed grain structure, no formation of coarse columnar crystals, and the like, and the average diameter of the crystal grains is only 1.2 to 9.3 μm, and the CrFeCoNi-based nanocomposite is composed of six elements of Cr, Fe, Co, Ni, Er, and Y. The performance of the CrFeCoNi-based nanocomposite prepared by the embodiment is tested, the hardness of the CrFeCoNi-based nanocomposite reaches 293.2HV, and the frictional wear rate at normal temperature is 3.879 multiplied by 10^-5mm³N^-1m^-1。

Example 2

The embodiment provides a high-entropy alloy nanocomposite, which takes CrFeCoNi as a matrix and takes graphene and nano ZrErYCoNi metal particles as reinforcements. The embodiment also provides a preparation method of the high-entropy alloy nanocomposite, which comprises the following steps:

2.1 selecting the multilayer reduced graphene with the purity of not less than 99.9 percent and the C with the purity of not less than 99.9 percent₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄Metal salt precursor powder and tungsten carbide grinding balls are used as raw materials, and the mass of each raw material is accurately weighed by using an electronic balance, wherein C in the metal salt precursor₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄In a molar ratio of 1: 1: 1: 1: 1, the mass ratio of the multilayer reduced graphene to the metal salt precursor powder is 1: 100, the mass ratio of the total mass of the multilayer reduced graphene and the metal salt precursor powder to the tungsten carbide grinding balls is 1: 300, the tungsten carbide grinding ball is the tungsten carbide grinding ball that the diameter is 15mm, 10mm and 5mm, and the quantity ratio of the tungsten carbide grinding ball that the diameter is 15mm, 10mm and 5mm is 3 in proper order: 3: 5; accurately weighing absolute ethyl alcohol by using a measuring cylinder and a beaker, wherein the volume ratio of the absolute ethyl alcohol to the tungsten carbide grinding balls is 10: 1, measuring absolute ethyl alcohol; pouring the weighed multilayer reduced graphene, the metal salt precursor powder, the tungsten carbide grinding balls and the absolute ethyl alcohol into a beaker together, and stirring and mixing uniformly to form a suspension;

2.2 carrying out ultrasonic dispersion treatment on the suspension obtained in the step 2.1, inserting an amplitude transformer of an ultrasonic disperser into a position 50mm below the liquid level of the suspension, carrying out ultrasonic dispersion treatment at the ultrasonic dispersion frequency of 25kHz for 300min, volatilizing most of absolute ethyl alcohol in the suspension to obtain the suspension with uniformly adhered graphene and C on the surface₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄The tungsten carbide grinding ball is carefully taken out and placed in a dry beaker, the beaker is placed in a drying oven, and the drying oven is used for drying for 300min at the drying temperature of 75 ℃ so as to remove graphene and C which are uniformly adhered to the surface₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄Residual moisture in the tungsten carbide grinding balls;

2.3 uniformly adhering graphene and C to the surface obtained in the step 2.2₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄Putting the tungsten carbide grinding balls into a heat treatment furnace, introducing argon with the purity of 99.99 percent into the heat treatment furnace as protective gas, and then uniformly adhering graphene and C on the surface at the heating rate of 80 ℃/min₂₀H₂₈ZrO₈、C₁₅H₂₁ErO₆、C₁₅H₂₄O₆Y、C₁₅H₂₁CoO₆And C₁₀H₁₄NiO₄The tungsten carbide grinding ball is heated to 600 ℃ from normal temperature for reduction reaction, and after the temperature is kept for 120min, the tungsten carbide grinding ball is naturally cooled to normal temperature along with the furnace to obtain the tungsten carbide grinding ball with the surface attached with graphene and nano ZrErYCoNi metal particles;

2.4 selecting CrFeCoNi high-entropy alloy powder as a matrix, wherein the purity of each element in the high-entropy alloy powder is not lower than 99.5%, the particle size of the high-entropy alloy powder is 45-95 μm, and the mass ratio of the tungsten carbide grinding balls with graphene and nano ZrErYCoNi metal particles attached to the surfaces to the CrFeCoNi high-entropy alloy powder is 25: 1, accurately weighing CrFeCoNi high-entropy alloy powder by using an electronic balance, adding tungsten carbide grinding balls with graphene and nano ZrErYCoNi metal particles attached to the surfaces and the CrFeCoNi high-entropy alloy powder into a hard alloy ball-milling tank, and carrying out ball-milling for 240min at the rotating speed of 420r/min to obtain composite powder of the graphene, the nano ZrErYCoNi metal particles and the CrFeCoNi;

2.5 screening the composite powder of the graphene, the nano ZrErYCoNi metal particles and the CrFeCoNi obtained in the step 2.4 by using a mechanical powder screening machine to obtain composite powder with the particle size of 45-95 μm, putting the screened composite powder into a powder feeding device powder cylinder of LAAM equipment, setting the laser power to be 880W, the scanning rate to be 0.7m/min, the powder feeding rate to be 8.3g/min, the lap joint rate to be 50%, the spot diameter to be 2.5mm, the defocusing amount to be 15.0mm, the layer height to be 0.5mm, the protective gas to be argon with the purity of 99.99%, and the protective gas flow to be 20L/min, and carrying out laser-assisted material increasing to obtain the CrFeCoNi-based nano composite material, wherein the size of the CrFeCoNi-based nano composite material is 100mm multiplied by 70mm by 5 mm.

Analyzing the composite powder of graphene, nano ZrErYCoNi metal particles and CrFeCoNi and the CrFeCoNi-based nanocomposite material prepared in this example, obtaining the result graphs shown in fig. 5-7, where fig. 5 is an SEM micrograph of the composite powder of graphene, nano ZrErYCoNi metal particles and CrFeCoNi at 40000 times; FIG. 6 is an EDS result chart of composite powder of graphene, nano ZrErYCoNi metal particles and CrFeCoNi at 40000 times; fig. 7 is an SEM micrograph of CrFeCoNi-based nanocomposites at 3000 times. As can be seen from fig. 5, the particle size of the ZrErYCoNi nano-metal particles prepared by the method of this embodiment is 50-200nm, the ZrErYCoNi nano-metal particles are regular in shape and uniformly generated on the surface of graphene, and the graphene is uniformly attached to the surface of CrFeCoNi. As can be seen from fig. 7, the CrFeCoNi-based nanocomposite prepared by the method of the present embodiment has fine crystal grains, a fine equiaxed grain structure, no formation of coarse columnar crystals, and the like, and the average diameter of the crystal grains is only 1.3 to 15.1 μm, and the CrFeCoNi-based nanocomposite is composed of seven elements of Cr, Fe, Co, Ni, Zr, Ce, and Er. The performance of the CrFeCoNi-based nanocomposite prepared by the embodiment is tested, the hardness of the CrFeCoNi-based nanocomposite reaches 292.9HV, and the frictional wear rate at normal temperature is 4.709 multiplied by 10^-5mm³N^-1m^-1。

Comparative example 1

The present example provides a CrFeCoNi high-entropy alloy, which is different from example 1 in that a high-entropy alloy nanomaterial is prepared by directly melting and depositing CrFeCoNi powder by a laser-assisted additive manufacturing technique without compounding CrFeCoNi powder, graphene and nano metal particles, and the preparation method of the CrFeCoNi high-entropy alloy comprises the following steps:

screening CrFeCoNi powder by using a mechanical powder sifter to obtain CrFeCoNi powder with the particle size of 45-95 mu m, ensuring that the CrFeCoNi powder can be continuously and stably sent into a molten pool, putting the CrFeCoNi powder obtained by screening into a powder feeder powder cylinder of LAAM equipment, setting the laser power to be 800W, the scanning rate to be 0.6m/min, the powder feeding rate to be 8.3g/min, the overlapping rate to be 50%, the spot diameter to be 2.5mm, the defocusing amount to be 15.0mm, the layer height to be 0.4mm, the protective gas to be argon with the purity of 99.99%, and the protective gas flow to be 20L/min, and carrying out laser-assisted material-increasing manufacturing to obtain the CrFeCoNi high-entropy alloy, wherein the size of the CrFeCoNi high-entropy alloy is 100mm multiplied by the width and the multiplied by the height to be 70mm by the 5 mm.

The CrFeCoNi high-entropy alloy prepared by the embodiment is analyzed, and a result graph shown in FIG. 8 is obtained, and FIG. 8 is an SEM (scanning electron microscope) microscopic morphology graph of the CrFeCoNi high-entropy alloy at 6000 times. As can be seen from fig. 8, the CrFeCoNi high-entropy alloy prepared by the method of this example has a large amount of coarse columnar grain structure, fine equiaxed grain features disappear, and intergranular crack defects are evident (as indicated by arrows in the figure). The performance of the CrFeCoNi high-entropy alloy prepared by the embodiment is tested, the hardness of the CrFeCoNi high-entropy alloy only reaches 182.6HV, and the frictional wear rate at normal temperature reaches 28.488 multiplied by 10^-5mm³N^-1m^-1All below the performance level of example 1.

Comparative example 2

The embodiment provides a CrFeCoNi-based composite material, which is different from embodiment 1 in that a graphene and nano-metal particle structure is not prepared on the surface of a tungsten carbide grinding ball in advance, the graphene and CrFeCoNi powder are directly subjected to mechanical ball milling, and the ball-milled powder is subjected to melting deposition by a laser-assisted additive manufacturing technology to prepare the CrFeCoNi-based composite material, and the preparation method of the CrFeCoNi-based composite material comprises the following steps:

selecting CrFeCoNi powder as a matrix, wherein the purity of each element in the high-entropy alloy powder is not lower than 99.5%, the particle size of the high-entropy alloy powder is 45-95 mu m, multilayer reduced graphene with the purity of not lower than 99.9% is used as a reinforcement, and the mass ratio of the multilayer graphene to the CrFeCoNi powder is 1: 100, weighing multilayer graphene and CrFeCoNi powder, adding the multilayer graphene and CrFeCoNi powder into a hard alloy ball-milling tank, and ball-milling for 300min at the rotating speed of 450r/min to obtain composite powder of graphene and CrFeCoNi;

screening the composite powder of graphene and CrFeCoNi by using a mechanical powder sifter to obtain the composite powder of graphene and CrFeCoNi with the particle size of 45-95 mu m, ensuring that the composite powder of graphene and CrFeCoNi can be continuously and stably sent into a molten pool, putting the screened composite powder of graphene and CrFeCoNi into a powder feeder powder cylinder of LAAM equipment, setting the laser power to be 800W, the scanning rate to be 0.6m/min, the powder feeding rate to be 8.3g/min, the lap joint rate to be 50%, the spot diameter to be 2.5mm, the defocusing amount to be 15.0mm, the layer height to be 0.4mm, the protective gas to be argon with the purity of 99.99%, and the protective gas flow to be 20L/min, and carrying out laser-assisted material increasing manufacturing to obtain the CrFeCoNi high-entropy alloy, wherein the size of the CrFeCoNi high-entropy alloy is 100mm, width and 70mm, 5 mm.

SEM analysis of the CrFeCoNi-based composite material obtained in this example revealed that the columnar crystal portion of the CrFeCoNi-based composite material obtained by the method of this example was transformed into equiaxed dendrites. The performance of the CrFeCoNi-based composite material prepared by the embodiment is tested, the hardness of the CrFeCoNi-based composite material only reaches 253.7HV, and the frictional wear rate at normal temperature is as high as 15.601 multiplied by 10^-5mm³N^-1m^-1All below the performance level of example 1.

According to the embodiment and the comparative example, the graphene and the nano metal particles are added into the high-entropy alloy matrix as the reinforcement, so that the refining effect of the nano metal particles and the graphene on crystal grains can be fully exerted on one hand, and the agglomeration phenomenon of the nano metal particles and the graphene can be effectively avoided by taking the grinding balls as macro carriers of the graphene and taking the graphene as micro carriers of the nano metal particles on the other hand; moreover, by changing the element composition, the raw material dosage ratio and the process parameters of the nano metal particles, the chemical composition, the morphology and the structural characteristics of the nano metal particles can be flexibly regulated and controlled, and the grain refinement, the grain boundary refinement and the performance improvement of the high-entropy alloy can be realized through the synergistic effect between the graphene and the nano metal particles, compared with the high-entropy alloy powder prepared by the traditional mechanical ball milling, the composite powder prepared by the method is beneficial to improving the mechanical property of the high-entropy alloy composite material, in addition, the high-entropy alloy composite material is prepared from the composite powder of the graphene, the nano metal particles and the high-entropy alloy by a laser-assisted additive manufacturing technology, so that the efficiency of preparing the high-entropy alloy composite material and the utilization rate of raw materials are improved, the manufacturing cost of the high-entropy alloy composite material is reduced, and the generation of intergranular cracks on large-size structural members can be effectively inhibited.

Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.