CN115323241A - TiZrHfNb nanocrystalline refractory high-entropy alloy and preparation method thereof - Google Patents
TiZrHfNb nanocrystalline refractory high-entropy alloy and preparation method thereof Download PDFInfo
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- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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Abstract
The invention provides a TiZrHfNb nanocrystalline refractory high-entropy alloy and a preparation method thereof, and the preparation method comprises the following specific processes: the high-entropy alloy comprises the following components in percentage by mass: zr: hf: nb =1:1:1:1. the preparation method comprises the following steps: firstly, preparing a high-entropy alloy ingot, namely preparing the high-entropy alloy according to the proportion of each element, uniformly mixing, putting the mixture into a vacuum arc melting furnace for melting, and finally cooling along with the furnace to obtain a refractory high-entropy alloy ingot with uniform tissue which is used as a target material; and secondly, ablating and condensing the prepared target material into nano-crystal powder by an inert gas condensation method, then pre-compacting the nano-crystal high-entropy alloy powder, transferring the particles to a high-pressure compacting device, and finally preparing the TiZrHfNb nano-crystal high-entropy alloy. According to the invention, the TiZrHfNb nanocrystalline refractory high-entropy alloy with uniform structure and excellent thermal stability is prepared by using an inert gas condensation method for the first time, and the prepared nanocrystalline high-entropy alloy nanocrystalline region is of a single-phase bcc structure, so that the mechanical property of the refractory high-entropy alloy is improved.
Description
Technical Field
The invention relates to the field of nano material preparation, and also relates to the field of a nano powder compacting method. In particular to a TiZrHfNb nanocrystalline refractory high-entropy alloy and a preparation method thereof, which realize the preparation of metal nano powder and the further deposition in an inert gas environment.
Background
High Entropy Alloys (HEAs) are considered as a novel alloy with great potential due to their special design concept and excellent comprehensive properties, and are expected to replace the existing traditional engineering materials. The refractory high-entropy alloy combines the concept of the high-entropy alloy with the design concept, and the main component of the refractory high-entropy alloy is a transition group refractory metal with a high melting point, so that the refractory high-entropy alloy is a special high-entropy alloy. The refractory high-entropy alloy has high strength, good oxidation resistance and corrosion resistance and excellent high-temperature mechanical property due to the addition of the high-melting-point element. Currently, both the academic circles and the engineering circles at home and abroad are seeking a novel high-temperature alloy which can adapt to increasingly harsh high-temperature use conditions.
The most prominent structural feature of nanocrystals (grain size <100 nm) is the extremely large grain boundary volume fraction, which results in significant changes in their physical, chemical and mechanical properties compared to its coarse-grained counterparts. Nanocrystalline metals as structural materials have ultrahigh strength, hardness and excellent wear resistance, but face the problem of reduced structural stability under force/thermal fields. At present, certain achievements are obtained in the aspect of improving the stability of nanocrystalline metal, and both theoretical and experimental researches show that the diversification of elements can reduce the thermodynamic driving force of grain boundary movement, so that alloying becomes a method for effectively improving the stability of nanocrystalline.
In order to solve the problems, the invention provides a novel structural material of a nanocrystalline high-entropy alloy, which aims to obtain a nanocrystalline metal system with excellent strength and stability, and the nanocrystallized refractory high-entropy alloy can greatly improve the temperature upper limit of the nanocrystalline metal for keeping the structure stable, and is an effective way for solving the contradiction between the strength and the stability of the nanocrystalline metal, and the problem is solved.
Therefore, it is necessary to adopt a method with nanocrystallization to prepare the refractory nanocrystalline high-entropy alloy.
Disclosure of Invention
In view of the defects and problems in the prior art and the system, the invention provides a preparation method of the TiZrHfNb nanocrystalline refractory high-entropy alloy aiming at the defects and requirements, so that the high-entropy alloy has excellent mechanical properties and good thermal stability.
In order to achieve the purpose, the invention adopts the following technical scheme:
the TiZrHfNb nanocrystalline refractory high-entropy alloy comprises the following components in percentage by mass: : ti: zr: hf: nb =1:1:1:1, the size of the nanocrystalline grain is 10-30nm, the prepared alloy has a single-phase bcc structure in a nanocrystalline region, and an amorphous region also exists in the alloy.
The invention provides a preparation method of TiZrHfNb nanocrystalline high-entropy alloy, which comprises the following steps:
step one, calculating and weighing according to the proportion, respectively obtaining the required amount of each substance, placing the required amount of each substance in a balance for weighing, then placing the raw materials in vacuum arc melting equipment to prepare the block high-entropy alloy with equal atomic ratio, carrying out ingot casting pretreatment, cutting the upper convex surface and the lower convex surface of the ingot casting, and removing the surface oxide layer.
Step two, taking the alloy ingot prepared by smelting as a target material, and depositing the target material into a nanocrystalline high-entropy alloy by adopting an inert gas condensation method, which specifically comprises the following steps:
an inert gas atmosphere container apparatus is provided: and the powder making chamber comprises an external laser access device and a laser source, and is used for exciting atoms in the metal ingot. Comprises a liquid nitrogen cooling tank for adsorbing the prepared metal nanopowder and depositing the metal nanopowder. Comprises a powder storage box for collecting and transporting the prepared metal nano-particles.
A copper roller which is cooled by liquid nitrogen and is enriched with nano powder in the powder making chamber;
pumping the powder making chamber to an ultrahigh vacuum state by the chamber through a mechanical pump and a molecular pump, and filling high-purity helium gas into the high-vacuum powder making chamber;
adjusting a laser path to enable a laser to aim at a metal ingot in a powder making chamber, adjusting the laser path to enable emitted laser to be vertical to the ingot by adjusting an angle, and adjusting the distance between the laser and the ingot;
after the laser and the metal cast ingot act, the evaporation and the preparation of the nano metal powder are completed so as to further deposit and collect the metal nano powder.
And (3) performing surface pretreatment on the metal target ingot with the purity of 99.99%, grinding, polishing to remove a surface oxide layer, ultrasonically cleaning by using alcohol, and fixing the metal target ingot at a corresponding target position in the cavity.
Closing the chamber, pumping the air pressure in the powder preparation chamber to an ultrahigh vacuum state which is lower than 8Pa through a mechanical pump and a molecular pump, then filling high-purity helium gas into the powder preparation chamber after pumping the high vacuum, and controlling the air pressure in the chamber to be stabilized between 400Pa and 600Pa according to the diameter of the powder to be prepared. The air pressure is not beyond the range, and the nano powder is agglomerated when the air pressure is beyond the range, so that the grain size of the subsequently prepared alloy reaches submicron or even micron.
And adjusting the laser path to enable the laser to aim at the metal ingot in the powder making chamber, adjusting the laser path to enable the emitted laser to be vertical to the ingot by adjusting the angle, and adjusting the distance from the laser to the ingot to enable the distance from the laser emitting lens to the target to be 75 cm. So as to ensure that the power of the laser on the target material is the maximum power. The emission power is between 80W and 120W, the wavelength is 980nm picosecond laser, and for the target ingot containing various different elements, the 980nm laser is selected to ensure that the nanometer metal powder is smoothly evaporated. The metal steam evaporated by laser irradiation and the inert helium gas in the cavity collide randomly and are cooled and condensed quickly to form new solid-phase nano powder, and the formed solid-phase nano powder is adsorbed and deposited on the surface of the copper roller due to the ultralow-temperature liquid nitrogen in the copper roller. After the laser and the metal target material act for a period of time, the original metal on the surface of the outer copper roller disappears and becomes black, and the metal nano particles are successfully deposited.
The laser used in the invention is a picosecond laser ultrafine powder alloy preparation device, the wavelength and the power of the laser are adjustable, the single pulse energy exceeds 80 muJ, the pulse frequency is 500kHz, and the pulse width is less than 16ps, so that the energy of the laser is enough to vaporize a local area acted by the laser and a target material in the single pulse time.
The tizhfnb nanocrystalline high entropy alloy powder was then exfoliated and collected in a square transfer container made of stainless steel, and after transferring the powder to a low compaction apparatus, the powder was compressed into granules with a diameter of 10mm under a uniaxial pressure of about 500 MPa. After this pre-compaction step, the granules were transferred to a high pressure compaction device, in which a pressure of 5GPa was applied for 3 minutes. Due to the high vapor pressure, the nanocrystalline high entropy alloy is finally press formed.
The method for preparing the nanocrystalline high-entropy alloy has the following advantages and effects:
1. compared with the common chemical method, the physical preparation method has the advantages that the physical preparation method is adopted, the metal target material is vaporized by laser heating, the preparation process of the physical method is simple, the complicated chemical reaction process is omitted, a plurality of chemicals which are easy to prepare and explode and generate poison are avoided when the nano metal particles are prepared by the chemical method, and the safety coefficient of the method is far higher than that of all chemical methods.
2. Aiming at metal simple substances or metal compound targets made of any different materials, the method can prepare nanoparticles with uniform and controllable sizes and regular shapes by adjusting laser wavelength, power and pressure parameters of helium in a cavity.
3. The invention does not need to use a large amount of chemical reagents to participate in the reaction in the preparation process, greatly reduces the production cost, and has the characteristics of high yield and high yield, thereby being suitable for industrial production.
4. The process of preparing the nanocrystalline is carried out in a cavity which is pre-treated by pumping ultra-high vacuum, and the subsequent reaction is completely realized in the atmosphere of low-pressure inert gas.
Drawings
To better illustrate the practical application of the invention, reference will now be made in brief to the accompanying drawings, which are used by way of example or in the prior art description.
FIG. 1 is a schematic view of an inert gas condensing apparatus according to the present invention.
FIG. 2 is a graph of annealing hardness of the nanocrystalline high entropy alloy of the invention at different temperatures.
FIG. 3 is different-temperature annealing XRD patterns of the nanocrystalline high-entropy alloy of the invention.
FIG. 4 shows the size distribution of the TiZrHfNb nanocrystalline high entropy alloy pre-fabricated TEM and nanocrystalline grains of the invention; the method comprises the following steps of (a) bright field imaging, (b) dark field imaging, (c) SAED pattern drawing and (d) grain size distribution of the prefabricated TiZrHfNb nanocrystalline high entropy alloy.
FIG. 5 is a HAADF-TEM image of a prefabricated TiZrHfNb nanocrystalline high entropy alloy of the present invention, the HAADF-TEM image of (a); corresponding to the chemical element distribution diagram, wherein (b) Hf, (c) Nb, (d) Ti and (e) Zr.
FIG. 6 is a TEM image of the pre-formed TiZrHfNb nanocrystalline high entropy alloy of the present invention, (a) a TEM image of the pre-formed TiZrHfNb nanocrystalline high entropy alloy; (b) And (c) are respectively a local enlarged image and a Fourier transform image of the corresponding area in the graph (a).
Detailed Description
The invention is further explained by combining the attached drawings
Although the high-entropy alloy is complex in composition, the microstructure of the high-entropy alloy is simple, and the high-entropy alloy mainly containing refractory elements is basically in a single-phase bcc crystal structure. The invention researches and researches the relation between the microstructure and the mechanical property in the nanocrystalline around the design concept of TiZrHfNb high entropy alloy and nanocrystalline. Firstly, preparing a refractory high-entropy alloy target material by using a vacuum arc melting method, and then further depositing the metal target material prepared in the first step into a nanocrystalline alloy by using an inert gas condensation method; secondly, heat treatment is carried out on the nanocrystalline alloy prepared by the method at different temperatures respectively to observe the microstructure and the stability of the nanocrystalline, and the hardness is measured to represent the mechanical property of the nanocrystalline alloy. Finally, the microstructure of part of the alloy sample is analyzed by adopting analytical means such as XRD, TEM and the like, and the result shows that the nanocrystalline alloy is in a bcc single-phase structure when being annealed at the temperature of less than 400 ℃, and a small amount of hcp phase appears after being annealed at the temperature of 600 ℃. In connection with the microstructure and the mechanical property, the TiZrHfNb nanocrystalline high entropy alloy has no obvious crystal grain growth when in service at the temperature of below 400 ℃, and can improve the mechanical property even to a certain extent. But phase change occurs at 600 ℃ or above, and crystal grains grow rapidly, the average crystal grain size is increased to about ten times of that of the crystal grains when the crystal grains are subjected to heat treatment at 600 ℃, nanocrystalline characteristics are gradually lost, and mechanical properties are also degraded. Therefore, how to improve the thermal stability of the tizhfnb nanocrystalline high-entropy alloy is a significant direction of the research on nanocrystals at present.
The method comprises the following specific steps:
example 1
Firstly, preparing a TiZrHfNb refractory high-entropy alloy:
(1) Calculating and weighing each element metal block with the purity of more than or equal to 99.95 percent of the TiZrHfNb refractory high-entropy alloy according to the equal atomic ratio, and calculating to obtain the mass precision of each sample at 5 multiplied by 10 -4 And g, taking out the raw materials from the inert gas glove box before weighing, and further polishing the raw materials subjected to proportioning to further remove an oxide layer on the surface of the raw materials. (2) The high-entropy alloy researched by the method is prepared by carrying out ultrasonic cleaning on a weighed sample for 5 minutes by using absolute ethyl alcohol and then adopting a vacuum arc melting method, and the method has the advantages of simple operation and low requirement on experimental equipment, and is a method adopted by many scholars at present. (3) High-melting-point metals such as W and Mo are used as electrodes, high-purity argon is introduced into a vacuum environment to be used as protective gas, the raw materials are melted by utilizing heat generated by arc discharge between a crucible and the electrodes in the argon atmosphere, and high current is adopted for melting in the melting process because the melting point of refractory high-entropy alloy elements is higher, and the raw materials are solidified in the crucible to form an alloy ingot. (4) During operation, the metal raw materials weighed according to a certain proportion are placed in a crucible of a vacuum arc melting furnace from high to low according to melting points, the sample chamber is closed and then vacuumized, and the vacuum degree reaches 1.5 multiplied by 10 -3 When Pa is needed, argon is recoiled to 410-450Pa and vacuumized again until the vacuum degree reaches 1.5 multiplied by 10 -3 And recoiling argon again until the pressure is 410-450Pa for smelting. And after six times of repeated rolling and smelting, obtaining an alloy ingot with uniform components, cooling after smelting, extracting argon, opening the furnace and taking out the prepared alloy ingot.
Secondly, depositing TiZrHfNb refractory nanocrystalline high-entropy alloy
The method comprises the following steps:
taking the alloy ingot prepared by smelting as a target material, and depositing the target material into a nanocrystalline high-entropy alloy by adopting an inert gas condensation method, which specifically comprises the following steps:
provided is a container device: and the powder preparation chamber comprises an external laser emitter for exciting atoms in the metal target. Comprises a liquid nitrogen cooling tank for depositing metal nano particles and adsorbing the metal nano particles in the cavity. Comprises a square column-shaped powder collecting tank for collecting metal nanoparticles when the metal nanoparticles are directly collected without depositing, and figure 1 is a schematic view of an inert gas condensing device.
Sealing the cavity, pumping the air pressure in the milling cavity to an ultrahigh vacuum state through a mechanical pump and a molecular pump, and filling high-purity helium gas into the milling cavity;
aiming an external laser at a metal target in a cavity for ingot casting, adjusting the laser angle to enable the emitted laser to be vertical to the ingot casting, and adjusting the distance between the laser and the target;
after the laser and the metal target act, the deposition of the superfine nano metal powder is completed.
And (3) performing surface pretreatment on the metal target material with the purity of 99.99%, grinding, polishing to remove a surface oxide layer, ultrasonically cleaning by using alcohol, and fixing at a corresponding position in the cavity.
Sealing the chamber, pumping the air pressure in the powder preparation chamber to an ultrahigh vacuum state which is lower than 8Pa through a mechanical pump and a molecular pump, slowly inputting high-purity helium gas into the powder preparation chamber after the vacuum is stable, and controlling the air pressure in the chamber to be stable between 400Pa and 600Pa according to the diameter of the powder to be prepared. The air pressure is not beyond the range, and the nano powder is agglomerated when the air pressure is beyond the range, so that the grain size of the subsequently prepared alloy reaches submicron or even micron.
And adjusting the laser path to enable the laser to aim at the metal ingot in the powder making chamber, adjusting the laser path to enable the emitted laser to be vertical to the ingot by adjusting the angle, and adjusting the distance from the laser to the ingot to enable the distance from the laser emitting lens to the target to be 75 cm. To ensure that the power of the laser on the target material is the maximum power. The emission power is between 80W and 120W, the wavelength is 980nm picosecond laser, and for the target ingot containing various different elements, the 980nm laser is selected to ensure that the nanometer metal powder is smoothly evaporated. The metal vapor evaporated by laser irradiation and inert helium gas in the cavity collide randomly and are cooled and condensed quickly to form new solid phase nanometer powder, and the formed solid phase nanometer powder is adsorbed and deposited on the surface of the copper roller due to ultralow temperature liquid nitrogen in the copper roller. After the laser and the metal target material act for a period of time, the original metal on the surface of the outer copper roller disappears and becomes black, and the metal nano particles are successfully deposited.
The laser used in the invention is a picosecond laser ultrafine powder alloy preparation device, the wavelength and the power of the laser are adjustable, the single pulse energy exceeds 100 muJ, the pulse frequency is 500kHz, and the pulse width is less than 15ps, so that the energy of the laser is enough to vaporize a local area acted by the laser and a target material in the single pulse time. The nanocrystalline high entropy alloy powder was then exfoliated and collected in a transfer container made of stainless steel, and after transferring the powder to a low-pressure compaction device, the powder was compressed into granules with a diameter of 10mm under a uniaxial pressure of about 500 MPa. After this pre-compaction step, the granules were transferred to a high pressure compaction device where a pressure of 5GPa was applied for 3 minutes at ambient temperature. Due to the high vapor pressure of Mn, nanocrystalline high entropy alloys are finally press formed.
FIG. 2 is a graph showing the hardness change of the nanocrystalline high-entropy alloy at different annealing temperatures, the hardness increase and decrease should be further analyzed and studied, and the reason for the hardness increase is analyzed to be that grain boundary relaxation occurs at the grain boundary during the annealing heat treatment at 200 ℃ and 400 ℃, which also conforms to the phenomenon that the grain growth degree is smaller when the annealing heat treatment is performed at 200 ℃ and 400 ℃. Grain boundary relaxation causes rearrangement of atoms in the crystal, reduces the degree of freedom of the grain boundary, and causes higher stability of the grain boundary, so that the hardness is slightly increased, and the subsequent annealing heat treatment at 600 ℃ obviously grows up grains, thereby satisfying the Hall-Peltier relationship, namely the phenomenon of hardness reduction.
Fig. 3 is an XRD diagram of different-temperature annealing of the nanocrystalline high-entropy alloy of the invention, the sample without heat treatment in the original state has no obvious difference from the samples after heat treatment at 200 ℃ and 400 ℃, even the diffraction peaks overlap greatly, which indicates that the tizrxhfnb nanocrystalline high-entropy alloy does not undergo phase transition when heat treatment is performed below 400 ℃, and is still in a bcc single-phase structure at room temperature, and the heat treatment below 400 ℃ does not affect the original crystal structure of the sample, i.e. the sample does not undergo phase transition. However, as can be seen from the figure, the XRD pattern of the sample is significantly different at a higher temperature, such as 600 ℃, than that at a lower temperature, the peak value of the diffraction peak becomes more complex, and it is known through comparing the standard diffraction peak patterns and analyzing that the phase composition of the sample changes from the original bcc single phase to two bcc phases plus one hcp phase, i.e. the phase transition from bcc structure to hcp occurs at 600 ℃.
FIG. 6 is a TEM image of the as-fabricated TiZrHfNb nanocrystalline high entropy alloy of the present invention. In the figure, where the figure (a) is a macroscopic region diagram, we have demarcated each crystal grain and amorphous region in the figure (a), and it can be seen that the sample contains an amorphous structure in addition to a part of the crystalline structure. Where (b) and (c) are magnified images of typical crystalline and amorphous structures in the region and their corresponding fourier-transformed images, the ordering of their atomic arrangement can be more clearly observed from (b), and the fourier transformation of the (b) image shows bcc structure in the crystalline structure, which also matches perfectly the XRD peaks measured for the as-fabricated tizhfnb high-entropy alloy nanocrystals. The image obtained by fourier transforming the graph (c) is shown as typical amorphous structure. This further demonstrates that the pre-formed tizhfnb high-entropy alloy nanocrystals have both crystalline and amorphous structures.
In connection with the microstructure and the mechanical property, the TiZrHfNb nanocrystalline high entropy alloy has no obvious crystal grain growth when in service at the temperature of below 400 ℃, and can improve the mechanical property even to a certain extent. But phase change occurs at 600 ℃ or above, and crystal grains grow rapidly, the average crystal grain size is increased to about ten times of that of the crystal grains when the crystal grains are subjected to heat treatment at 600 ℃, nanocrystalline characteristics are gradually lost, and mechanical properties are also degraded. Therefore, how to improve the thermal stability of the tizhfnb nanocrystalline high-entropy alloy is a significant direction for nanocrystalline research.
Claims (5)
- The TiZrHfNb nanocrystalline refractory high-entropy alloy is characterized in that the refractory high-entropy alloy comprises the following components in percentage by mass: ti: zr: hf: nb =1:1:1:1, the size of the nanocrystalline grain is 10-30nm.
- 2. The TiZrHfNb nanocrystalline refractory high entropy alloy of claim 1, wherein the nanocrystals are of a single phase bcc structure and an amorphous region is present in the alloy during fabrication.
- 3. The TiZrHfNb nanocrystalline refractory high-entropy alloy of claim 1, wherein the purity of each elemental element is not less than 99.99%.
- 4. A method for preparing the TiZrHfNb nanocrystalline refractory high-entropy alloy based on any one of claims 1 to 3, which comprises the following steps:s1, surface treatment of raw materialsCleaning Ti, hf, nb and Zr elementary substance raw materials, removing oxide skin and impurities on the surface, cleaning and drying; according to a molar ratio of 1:1:1: weighing Ti, hf, nb and Zr simple substances respectively according to the proportion of 1;s2, alloy smeltingMixing and placing alloy elements subjected to ultrasonic cleaning by using 99.7% absolute ethyl alcohol in a copper mold crucible of a high vacuum arc melting furnace according to the proportion, performing melting casting by using the vacuum arc melting furnace to preliminarily prepare an as-cast refractory high-entropy alloy, removing upper and lower convex planes of an ingot by using a diamond cutting machine, and polishing to remove oxide skin on the surface of the ingot to obtain a drum-shaped ingot with the thickness of about 9 mm;s3, preparation of nanocrystalline alloyProviding a container device which is provided with a powder making cavity, comprises an external laser emitter, is used for exciting atoms in a metal target material arranged in the powder making cavity, comprises a liquid nitrogen cooling tank, is used for depositing metal nano particles, and comprises a square column-shaped powder collecting tank, is used for directly collecting the metal nano particles without depositing the metal nano particles;metal atoms are attached to a copper roller on the outer side of a liquid nitrogen cooling tank in the powder preparation chamber, and the copper roller rotates around a shaft so as to further collect powder;sealing the cavity, pumping the air pressure in the powder preparation cavity to an ultrahigh vacuum state through a mechanical pump and a molecular pump, and slowly inputting high-purity helium gas into the powder preparation cavity;aiming an external laser at the metal target in the cavity, adjusting the laser angle to enable the emitted laser to be vertical to the target, and adjusting the distance between the laser and the target;after the laser and the metal target react, finishing the deposition of the high-entropy alloy nano metal powder when the surface of the target alloy turns black;closing the chamber, pumping the air pressure in the powder preparation chamber to an ultrahigh vacuum state which is lower than 8Pa through a mechanical pump and a molecular pump, then filling high-purity helium gas into the powder preparation chamber after pumping the high vacuum, and controlling the air pressure in the chamber to be stabilized between 400Pa and 600Pa according to the diameter of the powder to be prepared;adjusting the laser path to enable the laser to aim at a metal ingot in the powder making chamber, adjusting the laser path to enable the emitted laser to be vertical to the ingot by adjusting the angle, and adjusting the distance between the laser and the ingot to enable the distance between a laser emitting lens and a target to be 75 cm; so as to ensure that the power of the laser on the target is the maximum power; the emission power is between 80W and 120W, and the wavelength is 980nm picosecond laser;the metal steam evaporated by laser irradiation and the inert helium gas in the cavity collide randomly and are cooled and condensed quickly to form new solid-phase nano powder, and the formed solid-phase nano powder is adsorbed and deposited on the surface of the copper roller due to ultralow-temperature liquid nitrogen in the copper roller; after the laser and the metal target material act for a period of time, the original metal on the surface of the outer copper roller disappears and becomes black, and the metal nano particles are successfully deposited.
- 5. The preparation method according to claim 4, wherein the metal target is a metal target ingot with a purity of 99.99%, and is subjected to surface pretreatment, grinding, polishing to remove a surface oxide layer, ultrasonic cleaning with alcohol, and fixing at a corresponding target position in the cavity.
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| CN115948671A (en) * | 2023-02-17 | 2023-04-11 | 南京理工大学 | Material and method for further refining nanocrystalline grains through low-temperature annealing |
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