TWI674334B - Manufacturing method of high entropy alloy coating - Google Patents

Abstract

An embodiment of the present invention provides a method for manufacturing a high-entropy alloy coating, including: melting a high-entropy alloy material, wherein the high-entropy alloy material includes at least four metal elements, and the content of these metal elements is substantially the same; The gas atomization process forms the molten high-entropy alloy material into a high-entropy alloy powder; and the high-entropy alloy powder is heated and coated on the target substrate by a plasma spraying process.

Description

Manufacturing method of high-entropy alloy coating

The invention relates to a method for manufacturing a coating, and more particularly to a method for manufacturing a high-entropy alloy coating.

High entropy alloy (HEA) is an alloy material containing more than four main elements. In high-entropy alloys, each major element has a high atomic percentage, but each does not exceed about 35%. Therefore, the high-order effect caused by multiple elements can be fully utilized. With the random distribution of multiple element atoms, the formation of brittle compounds can be suppressed and the toughness of the material can be improved.

High-entropy alloy materials can be utilized in the form of blocks or coatings. The current method for manufacturing a high-entropy alloy coating includes making a high-entropy alloy block by smelting, and then grinding the high-entropy alloy block to form a high-entropy alloy powder. Subsequently, this high-entropy alloy powder is coated on a target substrate. However, defects are easily formed in the material during the grinding process, and the thermal energy generated by the grinding is more likely to change the material properties. As a result, the properties of high-entropy alloy coatings cannot be effectively controlled.

The invention provides a method for manufacturing a high-entropy alloy coating, which can effectively control the properties of the high-entropy alloy coating.

The manufacturing method of the high-entropy alloy coating of the present invention includes: melting a high-entropy alloy material, wherein the high-entropy alloy material includes at least four metal elements, and the content of these metal elements is substantially the same; Forming a molten high-entropy alloy material into a high-entropy alloy powder; and heating and coating the high-entropy alloy powder on a target substrate by a plasma spraying process.

In some embodiments, the molten high-entropy alloy material is rapidly cooled from a high temperature of 1150 ° C to 1500 ° C to a low temperature of 100 ° C to 250 ° C in a process of gas atomization.

In some embodiments, the high-entropy alloy powder is a substantially pure low-temperature phase.

In some embodiments, the low temperature phase is a body centered cubic phase.

In some embodiments, the high-entropy alloy powder has a low-temperature phase and a trace amount of a high-temperature phase, and the content ratio of the high-temperature phase is greater than 0% and less than 10%.

In some embodiments, the high-entropy alloy powder is substantially spherical and has an average particle diameter of 60 μm to 90 μm.

In some embodiments, the plasma gas in the plasma spraying process includes Ar gas and H ₂ , and the flow ratio of the Ar gas to H ₂ is 34: 1 to 1.5: 1.

In some embodiments, the power of the plasma spray process ranges from 20 kW to 55 kW.

The high-entropy alloy coating according to the embodiment of the present invention is the foregoing high-entropy alloy coating High-entropy alloy coating formed by the manufacturing method. The content ratio of the high-temperature phase of the high-entropy alloy coating is greater than 0% and less than 10%.

In some embodiments, the hardness of the high-entropy alloy coating is 230 HV to 600 HV, and the high-entropy alloy coating is ferromagnetic.

Based on the above, the embodiment of the present invention forms a high-entropy alloy powder by a gas atomization process, and uses a plasma spraying process to heat the high-entropy alloy powder and spray the heated high-entropy alloy powder on a target substrate to form a high-entropy alloy. coating. Compared with the high-entropy alloy powder obtained by pulverizing the block, the high-entropy alloy powder condensed from the liquid in the gas atomization process can have the advantages of uniform composition, less impurities, uniform shape, and good fluidity. In addition, during the gas atomization process, the liquid high-entropy alloy material is rapidly cooled to a low temperature. Therefore, the formed high-entropy alloy powder can be maintained in a low-temperature phase. On the other hand, since the high entropy alloy powder is heated by the plasma in the plasma spraying process for a very short time, it is difficult to generate a high temperature phase. In this way, the obtained high-entropy alloy coating can be a substantially uniform low-temperature phase. In some embodiments, methods such as screening the particle size of high-entropy alloy powder, controlling plasma power, adjusting plasma gas flow, and cooling the target substrate can be used to ensure that the high-entropy alloy coating is a substantially uniform low temperature phase. Therefore, it can be known that the above-mentioned manufacturing method of the high-entropy alloy coating can effectively control the crystalline phase of the high-entropy alloy coating. In this way, various physical properties of the high-entropy alloy coating can be adjusted more accurately.

In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.

10‧‧‧High-entropy alloy coating manufacturing equipment

100‧‧‧Gas atomization device

110‧‧‧ Plasma spraying device

AP‧‧‧Atomization Department

C‧‧‧Crucible

CB‧‧‧ powder collection cavity

CL‧‧‧High Entropy Alloy Coating

CP1, CP2‧‧‧‧Characteristic peaks

CS‧‧‧ Cooling System

DA, DB, DC, DD, DE, DF, DG, DH, DI, DJ, DK, DL, DM, DN, DO, DP, DQ, DR‧‧‧ data cable

E1, E2‧‧‧ electrodes

F‧‧‧Feeding port

GS‧‧‧Gas source

IN‧‧‧Air inlet

J‧‧‧ Plasma beam

MP‧‧‧Melting Department

NZ‧‧‧Nozzle

P‧‧‧ opening

TS‧‧‧ Target Base

FIG. 1 is a schematic diagram of a high-entropy alloy coating manufacturing apparatus according to some embodiments of the present invention.

FIG. 2A is a scanning electron microscope image of the high-entropy alloy powder of Experimental Examples 1 to 4. FIG.

FIG. 2B is a scanning electron microscope image of the high-entropy alloy powder of Experimental Examples 6 and 7. FIG.

FIG. 3 is an X-ray diffraction pattern of the high-entropy alloy powder used in Experimental Examples 1 to 7. FIG.

FIG. 4 is a plot of the saturation magnetization of the high-entropy alloy powders used in Experimental Example 1 to Experimental Example 7 with respect to the magnetic field strength.

FIG. 5 is X-ray diffraction patterns of the high-entropy alloy coatings of Experimental Examples 1 to 7. FIG.

FIG. 1 is a schematic diagram of a high-entropy alloy coating manufacturing apparatus 10 according to some embodiments of the present invention. In some embodiments, the high-entropy alloy coating CL may be formed on the target substrate TS by using the high-entropy alloy coating manufacturing apparatus 10.

Referring to FIG. 1, the high-entropy alloy coating manufacturing apparatus 10 may include a gas atomization device 100. In some embodiments, the gas atomizing device 100 includes a melting portion MP. The solid high-entropy alloy material is melted in the melting part MP to form a molten high-entropy alloy material. In some embodiments, a crucible C may be provided in the melting part MP. The solid high-entropy alloy material can be disposed in the crucible C, and is transformed into a molten state by being heated by, for example, electromagnetic induction heating. At this time, the temperature of the molten high-entropy alloy material may be in a range of 1150 ° C to 1500 ° C. In some embodiments, when the high-entropy alloy material is heated, the interior of the melting portion MP may be maintained in a vacuum environment. In addition, an inert gas and / or a reducing gas may be passed into the melting portion MP to avoid oxidation of the high-entropy alloy material. For example, the inert gas may include He gas, Ar gas, and the like, and the inert gas may include N ₂ , H _2, and the like. In some embodiments, the high-entropy alloy material includes more than four metal elements. These metal elements are the main elements of high-entropy alloy materials and have substantially equal atomic percentages. For example, the atomic percentage of each metal element is in the range of 5 at% to 35 at%. In some embodiments, the metal element of the high-entropy alloy material may include at least four of the group consisting of Ni, Fe, Co, Cr, Al, Ti, Zr, Cu, Mn, and Si. For example, the high-entropy alloy material may be Ni ₂ FeCoCrAl _x Ti _y . x is greater than or equal to 0 and less than or equal to 1.5. y is greater than or equal to 0 and less than or equal to 1.0.

In some embodiments, the gas atomizing device 100 further includes an atomizing part AP. The atomizing part AP may communicate with the melting part MP. In this way, the molten high-entropy alloy material can enter the atomizing part AP from the melting part MP. In some embodiments, the atomizing portion AP includes a nozzle NZ. The high-entropy alloy material in a molten state can be input to the nozzle NZ from the melting portion MP, and is ejected as a fluid. In addition, the atomizing part AP may further include a gas source GS. The gas source GS can be disposed on the cavity wall of the atomizing part AP, and is used to form a high-pressure gas flow in the atomizing part AP (as shown by the arrow near the nozzle NZ). This high-pressure gas flow can be directed to impinge on the high-entropy alloy fluid ejected from the nozzle NZ to form minute droplets. These droplets can fly and cool inside the atomizing part AP to form a high-entropy alloy powder. In some embodiments, the gas of the gas source GS may include an inert gas and / or a reducing gas. For example, the inert gas may include He gas, Ar gas, N ₂ and the like, and the reducing gas may include H ₂ or the like. By passing an inert gas and / or a reducing gas into the atomizing part AP, the high-entropy alloy fluid can be more prevented from being oxidized during the condensation process. Furthermore, in some embodiments, the atomizing part AP may further include a suction system (not shown) configured to maintain the inside of the atomizing part AP under a vacuum environment.

In some embodiments, the atomizing part AP may further include a powder collection cavity CB. The powder collection cavity CB may be connected to the cavity wall of the atomizing part AP and configured to collect high-entropy alloy powder. In some embodiments, the number of the powder collection chambers CB may be a majority, and may be disposed at different positions on the cavity wall of the atomizing portion AP. Generally speaking, the powder collection cavity CB closer to the nozzle NZ can collect high-entropy alloy powder with a smaller particle diameter, and the powder collection cavity CB closer to the nozzle NZ can collect high-entropy with a larger particle diameter Alloy powder. Taking the gas atomizing device 100 shown in FIG. 1 as an example, the atomizing part AP may include two powder collection cavities CB, which are respectively disposed on the side wall and the bottom of the atomizing part AP. However, those with ordinary knowledge in the art can adjust the number and position of the powder collection chambers CB according to the requirements of the process, and the embodiments of the present invention are not limited thereto. In addition, in some embodiments, the powder collection cavity CB disposed on the side wall of the atomizing portion AP may be communicated with the gas source GS, so that the gas in the atomizing portion AP may return to the gas source GS. In addition, the high-entropy alloy powder obtained by the above-mentioned gas atomization process may have the characteristics of uniform shape and good fluidity. In some embodiments, the high-entropy alloy liquid can be rapidly cooled from a high temperature of about 1500 ° C to a low temperature below 300 ° C (for example, (Eg, 100 ° C to 250 ° C or 150 ° C to 250 ° C) to form a high-entropy alloy powder. In addition, the rapid cooling time can be within 5 seconds. In some embodiments, based on this rapid cooling process, the entire high-entropy alloy powder formed can be maintained in a low-temperature phase. In other words, the high-entropy alloy powder is a substantially pure low-temperature phase. In other embodiments, the formed high-entropy alloy powder has a low-temperature phase and a small amount of a high-temperature phase. For example, the content ratio of the high-temperature phase may be less than 10%, for example, in the range of 0% to 5% or 0% to 3%. Taking the high-entropy alloy material as NiFeCoCrAl as an example, the low-temperature phase may be a body-centered cubic (BCC) phase, and the high-temperature phase may be a face-centered cubic (FCC) phase.

The high-entropy alloy coating manufacturing apparatus 10 may further include a plasma spray device 110. The high-entropy alloy powder obtained by the gas atomizing device 100 can be fed to the plasma spraying device 110. In addition, the plasma spraying device 110 can heat the high-entropy alloy powder and apply the heat-softened high-entropy alloy powder to the target substrate TS. In this way, a high-entropy alloy coating CL can be formed on the target substrate TS.

In some embodiments, the plasma spraying device 110 includes an electrode E1 and an electrode E2 for generating a plasma. The electrode E1 can serve as an anode. In some embodiments, the electrode E1 may be configured as a nozzle. In these embodiments, the nozzle-shaped electrode E1 has an opening P. On the other hand, the electrode E2 is disposed on one side of the electrode E1 and can serve as a cathode. The plasma gas used to form the plasma may flow from the air inlet IN through a region between the electrode E1 and the electrode E2. In some embodiments, the plasma gas includes Ar gas and diatomic gas. For example, the diatomic gas may be H ₂ . The plasma gas between the electrodes E1 and E2 can be released by the bias voltage between the electrodes E1 and E2 to form a plasma. In addition, the plasma may be ejected through the opening P of the electrode E1, and a plasma jet J may be formed. In some embodiments, the feeding port F of the high-entropy alloy powder may be disposed near the opening P of the electrode E1, so that the high-entropy alloy powder fed to the plasma spraying device 110 is immediately heated by the plasma. In some embodiments, the heated high-entropy alloy powder may be in a semi-fused state and reach the surface of the target substrate TS along the path of the plasma. The heat-softened high-entropy alloy powder can be stacked on the target substrate TS to form a high-entropy alloy coating CL. In some embodiments, the plasma spraying device 110 may further include a cooling system CS. The cooling system CS may be in thermal contact with the electrodes E1 and E2 to cool the electrodes E1 and E2. In some embodiments, the cooling system CS may be a water cooling system, but the embodiment of the present invention is not limited thereto.

Since the high entropy alloy powder is heated by the plasma for a very short time (for example, less than one ten thousandth of a second), the obtained high entropy alloy coating CL can have a uniform crystalline phase. In some embodiments, the high-entropy alloy powder may be screened and fed to the plasma spraying device 110. After screening, the average particle diameter (or D50) of the high-entropy alloy powder can be 60 μm to 90 μm. In these embodiments, the high-entropy alloy powder is not easily heated completely, but can be maintained in a low-temperature phase, and still has good powder flowability. As such, in some embodiments, the entire high-entropy alloy coating CL formed may be substantially a low-temperature phase. In other embodiments, the high-entropy alloy coating CL includes a majority of low-temperature phases and a small amount of high-temperature phases. For example, the content ratio of the high-temperature phase in the high-entropy alloy coating CL may be less than 10%, for example, in the range of 0% to 5% or 0% to 3%. On the other hand, when fed to the plasma spraying device 110, the average grain size of the high-entropy alloy powder is When the diameter is less than 60 μm, a high-temperature phase may be generated by plasma heating. In addition, when the average particle diameter of the high-entropy alloy powder fed to the plasma spraying device 110 is greater than 90 μm, the fluidity of the high-entropy alloy powder may be reduced, and the smooth feeding may not be performed.

In the embodiment where the high-entropy alloy material is NiFeCoCrAl, the low-temperature phase is a BCC phase and the high-temperature phase is an FCC phase. Compared with the FCC phase, the BCC phase has fewer slip systems and therefore has higher mechanical strength (for example, hardness). In addition, the BCC phase is ferromagnetic and has a high saturation magnetization. In comparison, the FCC phase is paramagnetic and has a low saturation magnetization. In some embodiments, the high-entropy alloy coating CL is substantially a BCC pure phase and can be used as a functional coating or a ferromagnetic coating to enhance the hardness of the workpiece. In these embodiments, the hardness of the high-entropy alloy coating CL ranges from 230 HV to 600 HV, such as 238 HV to 427 HV. In addition, the saturation magnetization of the high-entropy alloy coating CL may be in a range of 10 emu / g to 100 emu / g.

In addition to screening the particle size of the high-entropy alloy powder, it is also possible to assist in controlling the heating degree of the high-entropy alloy powder by adjusting the plasma power and plasma gas flow. The higher the plasma temperature, the more completely the high-entropy alloy powder is heated, and the easier it is to generate a high-temperature phase. It can be known that the crystalline phase of the high-entropy alloy coating CL can be controlled by adjusting the plasma power and the plasma gas flow rate so that the high-entropy alloy coating CL is substantially a pure low-temperature phase. In some embodiments, the plasma power can range from 20 kW to 55 kW. In addition, increasing the flow rate of Ar gas can increase the temperature of the plasma, while increasing the flow rate of the diatomic gas can stably maintain the plasma. In some embodiments, the flow ratio of the Ar gas to the diatomic gas may be 34: 1 to 1.5: 1. In these embodiments, the flow rate range of Ar can be 40slpm to 75slpm, and the flow rate range of diatomic gas can be 1.5 slpm to 9.5 slpm. Furthermore, in some embodiments, the target substrate TS can be cooled during the spraying process. In this way, it can be further ensured that the high-entropy alloy coating is maintained in a low-temperature phase.

Based on the above, the embodiment of the present invention forms a high-entropy alloy powder by a gas atomization process, and uses a plasma spraying process to heat the high-entropy alloy powder and spray the heated high-entropy alloy powder on a target substrate to form a high-entropy alloy. coating. Compared with the high-entropy alloy powder obtained by pulverizing the block, the high-entropy alloy powder condensed from the liquid in the gas atomization process can have the advantages of uniform composition, less impurities, uniform shape, and good fluidity. In addition, during the gas atomization process, the liquid high-entropy alloy material is rapidly cooled to a low temperature. Therefore, the formed high-entropy alloy powder can be maintained in a low-temperature phase. On the other hand, since the high entropy alloy powder is heated by the plasma in the plasma spraying process for a very short time, it is difficult to generate a high temperature phase. In this way, the obtained high-entropy alloy coating can be a substantially uniform low-temperature phase. In some embodiments, methods such as screening the particle size of high-entropy alloy powder, controlling plasma power, adjusting plasma gas flow, and cooling the target substrate can be used to ensure that the high-entropy alloy coating is a substantially uniform low-temperature phase. Therefore, it can be known that the above-mentioned manufacturing method of the high-entropy alloy coating can effectively control the crystalline phase of the high-entropy alloy coating. In this way, various physical properties of the high-entropy alloy coating can be adjusted more accurately.

In the following, the effects of the embodiments of the present invention are verified by Experimental Examples 1 to 7.

<Preparation of High Entropy Alloy Powder>

Referring to FIG. 1, the purity is set in the melting section MP of the gas atomizing device 100. A metal block (manufactured by Alfa Aesar) of 99.95% Al, Co, Cr, Fe, and Ni is melted and mixed in substantially equal proportions to form a molten high-entropy alloy material. The melting part MP is maintained in an Ar gas environment, and the molten high-entropy alloy material is stirred in a vibration manner during the melting and mixing process. The molten high-entropy alloy material then enters the atomizing part AP and is ejected from the nozzle NZ as a fluid. High-entropy alloy fluids are impacted by high-pressure gas streams to form small droplets. These droplets fly within the atomizing part AP and are rapidly cooled to solidify. In this way, a high-entropy alloy powder is formed. Next, the high-entropy alloy powder is screened to take out the high-entropy alloy powder having a specific average particle size range.

<Plasma spraying process>

Next, the screened high-entropy alloy powder is input to the plasma spraying apparatus 110 using N ₂ as a carrier gas. The conveying rate of the high-entropy alloy powder is about 30 g / min. In addition, a target substrate TS is provided. The target substrate TS is a 304 stainless steel plate, and is sandblasted and cleaned before the plasma spraying process. The plasma spraying device 110 includes a plasma generating device including an electrode E1 and an electrode E2 installed on a robot arm (not shown) to control a spraying distance and a spraying angle. In the spraying process, the target substrate TS can be moved and sprayed in a scanning manner. Specifically, the target substrate may be moved in the column direction in each scanning cycle. Then, the target substrate (about 140 mm) can be moved in the row direction for the next scanning cycle. Plasma gas includes Ar gas and H ₂ . In the plasma spraying process, the target substrate TS is cooled by an air jet, and the high-entropy alloy powder that does not adhere well to the target substrate TS and / or the high-entropy that is not softened by heat is removed. Alloy powder. The thickness of the high-entropy alloy coating layer CL formed on the target substrate TS is calculated by the number of plasma spraying. In the following experimental example, the plasma spraying process is performed 10 times, so the thickness of the high-entropy alloy coating CL formed is about 150 μm to 200 μm.

The following Table 1 summarizes the average particle size range of high-entropy alloy powders from Experimental Examples 1 to 7, and various plasma process parameters.

〈High Entropy Alloy Powder Analysis〉

The appearance and composition of the high-entropy alloy powders used in Experimental Examples 1 to 7 were observed with a scanning electron microscope (JSM6500F (trade name) produced by JEOL) using an energy dispersive spectrometer (EDS) device. . In addition, the high-entropy alloy powders used in Experimental Examples 1 to 7 were subjected to a crystalline phase by an XDS2000 (trade name) X-ray diffractometer produced by Scintag. Analysis. Specifically, the X-ray diffraction analysis was performed using Cu Kα radiation and performed at room temperature. In addition, by using a magnetic property measurement system (MPMS) manufactured by Quantum Design in a temperature range of 10K to 400K and an applied magnetic field range of 0T to 7T, it is used for Experimental Examples 1 to Experimental Examples. The high-entropy alloy powder of 7 was subjected to magnetic analysis.

FIG. 2A is a scanning electron microscope image of the high-entropy alloy powder of Experimental Examples 1 to 4. FIG. FIG. 2B is a scanning electron microscope image of the high-entropy alloy powder of Experimental Examples 6 and 7. FIG.

Please refer to FIG. 2A and FIG. 2B. The high-entropy alloy powders used in Experimental Examples 1-4, 6, and 7 have the same shape and are substantially spherical. In addition, as can be seen from FIG. 2B, the high-entropy alloy powder (Experimental Examples 6 and 7) having a particle size of 60 μm to 90 μm was also substantially spherical. In addition, compared with FIG. 2A, the particle size of the powder shown in FIG. 2B is more consistent. On the other hand, although the image of the high-entropy alloy powder of Experimental Example 5 is not provided, the high-entropy alloy powder used in Experimental Example 5 is the high-entropy alloy powder used in Experimental Examples 1-4 and the experimental example 6, Mixing of 7 high entropy alloy powder. From this, it can be seen that the high-entropy alloy powder used in Experimental Example 5 can also have a uniform outer shape (spherical shape). In addition, Table 2 below shows the composition ratios of the energy dispersive spectrometers to the high-entropy alloy powders used in Experimental Examples 6 and 7.

Please refer to Table 2 above. The content of each element is roughly the same, and they can all be used as the main elements of high-entropy alloys.

FIG. 3 is an X-ray diffraction pattern of the high-entropy alloy powder used in Experimental Examples 1 to 7. FIG.

Please refer to FIG. 3, data lines DA to DG are X-ray diffraction patterns of high-entropy alloy powder without particle size screening. The high-entropy alloy powder represented by data line DA is not annealed. Data line DB, data line DC, data line DD, data line DE, data line DF, and data line DG represent high entropy after annealing at 500 ° C, 600 ° C, 700 ° C, 800 ° C, 900 ° C, and 1000 ° C for 48 hours, respectively. Alloy powder. The characteristic peak CP1 represents the BCC phase, and the characteristic peak CP2 represents the FCC phase. From the data line DA to the data line DG, it can be observed that the FCC phase needs to be generated by increasing the annealing temperature above 600 ° C, and the intensity of the characteristic peak of the FCC phase (that is, the characteristic peak CP2) increases as the annealing temperature increases. On the other hand, the high-entropy alloy powder that is not annealed and annealed at 500 ° C is essentially a BCC pure phase. Therefore, it can be known that the high-entropy alloy powder obtained by the gas atomization process according to the embodiment of the present invention can be a BCC pure phase. It should be noted that in Experimental Examples 1 to 7, the high-entropy alloy powders fed to the plasma spraying device were not annealed, that is, they were all BCC pure phases shown by data line DA.

FIG. 4 is a plot of the saturation magnetization of the high-entropy alloy powders used in Experimental Example 1 to Experimental Example 7 with respect to the magnetic field strength.

Please refer to FIG. 4, the data line DH to the data line DK are the spectra of the saturation magnetization versus magnetic field strength of the high-entropy alloy powder without particle size screening. The high-entropy alloy powder represented by the data line DH is not annealed. Data line DI, data line DJ, and data line DK respectively represent high-entropy alloy powders that have been annealed at 500 ° C, 1000 ° C, and 1200 ° C. From the data line DH to the data line DK, it can be observed that as the annealing temperature increases, the saturation magnetization increases first and then gradually decreases. Specifically, when the annealing temperature is less than 500 ° C, the saturation magnetization amount increases as the annealing temperature increases. When the annealing temperature is higher than 500 ° C, the saturation magnetization decreases as the annealing temperature increases. It can be seen that the high-entropy alloy powder is ferromagnetic before the annealing temperature reaches about 500 ° C, and it is paramagnetic when the annealing temperature is higher than about 500 ° C. Combining the results of Fig. 3 and Fig. 4 can be inferred that the transition between ferromagnetic and paramagnetic should come from the transition between BCC phase and FCC phase. In other words, the BCC phase is ferromagnetic and the FCC phase is paramagnetic.

〈High Entropy Alloy Coating Analysis〉

The crystal phase of the high-entropy alloy coating CL was analyzed by an XDS2000 (trade name) X-ray diffractometer produced by Scintag. Specifically, the X-ray diffraction analysis was performed using Cu Kα radiation and performed at room temperature. In addition, the hardness of the high-entropy alloy coating was analyzed with a Vickers hardness tester under a load of 300 grams.

FIG. 5 is X-ray diffraction patterns of the high-entropy alloy coatings of Experimental Examples 1 to 7. FIG.

Please refer to FIG. 5, the data lines DL to DR respectively represent the experimental example 1 X-ray diffraction pattern of the high-entropy alloy coating CL to Experimental Example 7. The high-entropy alloy powders used to form Experimental Examples 1 to 7 are not annealed, that is, they all maintain the BCC pure phase (as shown by the data line DA in FIG. 3) and ferromagnetism. From the data line DL, data line DM, data line DN, data line DO, and data line DP, the particle diameter of the high-entropy alloy powder fed to the plasma spraying device can be observed in the range of 10 μm to 60 μm or in the range of 10 μm to 90 μm. In the internal phase, the formed high-entropy alloy coatings are all mixed phases including FCC phase and BCC phase (characteristic peak CP1 and characteristic peak CP2 appear at the same time). In addition, the content of the FCC phase (ie, the intensity of the characteristic peak CP2) increases as the plasma power and the Ar gas flow rate increase. On the other hand, from the data lines DQ and DR, it can be observed that when the particle diameter of the high-entropy alloy powder fed to the plasma spraying device is in the range of 60 μm to 90 μm, the formed high-entropy alloy coating can be maintained in BCC purity. Phase (only characteristic peak CP1 appears). Even if data lines DQ and DR correspond to experimental examples 6 and 7 using higher plasma power and Ar gas flow rate than other experimental examples, no FCC phase (ie, characteristic peak CP2) was observed. It can be known from this that the particle size of the high-entropy alloy powder fed to the plasma spraying device is one of the key factors determining whether the high-entropy alloy coating remains as a BCC pure phase.

The following table III summarizes the hardness of the high-entropy alloy coatings of Experimental Examples 1 to 7.

Please refer to FIG. 5 and Table 3 above. Compared with Experimental Examples 1-5, the high entropy alloy coatings of Experimental Examples 6 and 7 show significantly higher hardness. This result is compared with FIG. 5 to show that the high entropy alloy coating can have substantially higher hardness when the high entropy alloy coating is a pure BCC phase, compared to the FCC phase and the BCC phase of the high entropy alloy coating.

Looking at the above experimental results, it can be known that when the particle size of the high-entropy alloy powder is in a specific range, and with the control of the plasma process conditions, the crystal phase of the high-entropy alloy coating formed can be adjusted. In this way, the physical properties of the obtained high-entropy alloy coating can be controlled, such as hardness and magnetic properties.

In summary, the embodiment of the present invention forms a high-entropy alloy powder by a gas atomization process, and uses a plasma spraying process to heat the high-entropy alloy powder and spray the heated high-entropy alloy powder on a target substrate to form a high Entropy alloy coating. Compared with the high-entropy alloy powder obtained by pulverizing the block, the high-entropy alloy powder condensed from the liquid in the gas atomization process can have the advantages of uniform composition, less impurities, uniform shape, and good fluidity. In addition, during the gas atomization process, the liquid high-entropy alloy material is rapidly cooled to a low temperature. Therefore, the formed high-entropy alloy powder can be maintained in a low-temperature phase. On the other hand, the high entropy alloy powder is heated by the plasma during the plasma spraying process for a very long time. Short, it is not easy to generate high temperature phase. In this way, the obtained high-entropy alloy coating can be a substantially uniform low-temperature phase. In some embodiments, methods such as screening the particle size of high-entropy alloy powder, controlling plasma power, adjusting plasma gas flow, and cooling the target substrate can be used to ensure that the high-entropy alloy coating is a substantially uniform low-temperature phase. Therefore, it can be known that the above-mentioned manufacturing method of the high-entropy alloy coating can effectively control the crystalline phase of the high-entropy alloy coating. In this way, various physical properties of the high-entropy alloy coating can be adjusted more accurately.

Although the present invention has been disclosed as above with the examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims (10)

A method for manufacturing a high-entropy alloy coating includes: melting a high-entropy alloy material, wherein the high-entropy alloy material includes at least four metal elements, and the content of the at least four metal elements is substantially the same, wherein The at least four metal elements are selected from the group consisting of Ni, Fe, Co, Cr, Al, Ti, Zr, Cu, Mn, Si; the high entropy of the molten state is melted by a gas atomization process The alloy material is formed as a high-entropy alloy powder; and the high-entropy alloy powder is heated and coated on a target substrate by a plasma spraying process, wherein the plasma spraying process generates plasma sprayed toward the target substrate Beam, the high-entropy alloy powder is heated by the plasma beam, and the high-entropy alloy powder softened by heat flies to the target substrate along the spray direction of the plasma beam. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent application range, wherein the molten high-entropy alloy material is rapidly heated from a high temperature of 1150 ° C to 1500 ° C within 5 seconds during the gas atomization process Cool to a low temperature of 100 ° C to 250 ° C. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent application range, wherein the high-entropy alloy powder is substantially a homogeneous low-temperature phase. The method for manufacturing a high-entropy alloy coating as described in item 3 of the patent application range, wherein the low-temperature phase is a body-centered cubic phase. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent scope, wherein the high-entropy alloy powder has a low-temperature phase and a trace of high-temperature phase, and the content ratio of the high-temperature phase is greater than 0% and less than 10 %. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent application range, wherein the high-entropy alloy powder is substantially spherical and has an average particle diameter of 60 μm to 90 μm. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent application range, wherein the plasma gas of the plasma spraying process includes Ar gas and H ₂ , and the flow ratio of the Ar gas to the H ₂ From 34: 1 to 1.5: 1. The method for manufacturing a high-entropy alloy coating as described in item 1 of the patent application range, wherein the power range of the plasma spraying process is 20 kW to 55.5 kW. A high-entropy alloy coating is a high-entropy alloy coating formed by the method for manufacturing a high-entropy alloy coating according to any one of patent application items 1 to 8, wherein the high-entropy alloy coating The content ratio of the high-temperature phase of the layer is greater than or equal to 0% and less than 10%. The high-entropy alloy coating according to item 9 of the patent application range, wherein the hardness of the high-entropy alloy coating is 230HV to 600HV, and the high-entropy alloy coating is ferromagnetic.