A controllable preparation method for a BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating

Abstract

This invention belongs to the field of tool coating preparation technology, specifically relating to a controllable preparation method of a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating. A BCC+Laves nanosheet biphase eutectic high-entropy alloy coating is prepared on the surface of high-speed steel using laser cladding technology. Because the substrate material and coating are metallurgically bonded, they exhibit good bonding strength. Simultaneously, the carbon element in the substrate penetrates into the coating and combines with the strong carbon element Nb to form NbC particles, which can improve the hardness and wear resistance of the coating to a certain extent. Furthermore, the Fe-Cr type BCC solid solution phase itself also exhibits high hardness and wear resistance. Therefore, this method has significant development potential in the field of high-speed steel tool surface modification, and can significantly extend the service life of high-speed cutting tools while reducing manufacturing costs.

Description

Technical Field

[0001] This invention belongs to the field of tool coating preparation technology, specifically relating to a controllable preparation method of a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating. Background Technology

[0002] Improving the overall performance of coated cutting tools, rationally designing the chemical composition of the coating, and improving the bonding strength between the tool coating and the substrate to adapt to high-speed cutting technology are key issues in the development of the manufacturing industry.

[0003] BCC+Laves nanosheet biphase eutectic high-entropy alloy coating is a novel alloy with high hardness, high wear resistance, and excellent resistance to high-temperature softening. It is expected to be prepared into a high-performance coating that can greatly improve the hardness and wear resistance of cutting tools at room temperature and high temperature.

[0004] There are some existing methods for preparing BCC+Laves alloys. For example, patent document CN112553488B discloses a CrAlNbTiVZr high-entropy alloy material and its preparation method. Its elemental composition is CrAlNbTiVZr in an equimolar ratio of 1:1:1:1:1:1. Its as-cast microstructure consists of BCC and HCP solid solutions and a small amount of Laves phase. The preparation method is as follows: (1) Ultrasonic treatment: Clean each material with acetone solution and anhydrous ethanol for later use; (2) Weighing: Weigh each material in an equimolar ratio; (3) Melting: Use a non-consumable vacuum arc melting furnace to repeatedly melt the weighed materials to prepare the as-cast high-entropy alloy; (4) Heat treatment: Use a vacuum tube furnace to perform homogenization annealing of the as-cast high-entropy alloy at 980-1100℃ for 2-4 hours. However, it requires repeated melting, and the melting process takes a long time. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating and its controllable preparation method.

[0006] Specifically, this is achieved through the following technical solutions:

[0007] 1. A BCC+Laves nanosheet biphase eutectic high-entropy alloy coating, wherein the composition of the alloy coating is, in molar ratio: Al:Fe:Cr:Mo:Nb=1:1:1:1:x, x=0.4, 0.6, 0.8.

[0008] Furthermore, the BCC phase and the Laves phase in the alloy coating form a lamellar structure; the BCC phase is mainly Fe-Cr solid solution, and the Laves phase is mainly Fe2Nb.

[0009] 2. The controllable preparation method of the above-mentioned BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating includes the following steps:

[0010] (1) Ingredient mixing: Weigh the corresponding weight of alloy powder according to the proportion and put it into the ball mill jar. Then add stainless steel balls with a mass of 8 times that of the alloy powder and ball mill in a high-energy planetary ball mill for 1.5-2.5 hours at a speed of 300 r / min.

[0011] Furthermore, the average particle size of the alloy powder is 150-300 mesh.

[0012] (2) Forming the blank: Place a mold with dimensions of 40mm × 15mm × 12mm on a high-speed steel plate: Pour the powder after ball milling in step (1) into the mold with a spoon and scrape it until it is level with the mold;

[0013] (3) Cladding: Using a circular spot with a diameter of Φ=4mm, under the set laser parameters: P=1800W, v=5mm / s, laser focal length 300mm, single-pass cladding is performed according to the set path;

[0014] (4) Quenching: The coated sample is quenched in water to obtain an ultrafine nanosheet eutectic structure.

[0015] Furthermore, the formation of the eutectic structure in the coating was controlled by changing the molar ratio of Fe to Nb. With the increase of Nb content, the microstructure of the coating changed from a single BCC phase to a BCC+Laves nanosheet biphase.

[0016] 3. Microstructure Observation: The clad coating was cut into 10mm x 10mm x 5mm rectangular blocks using a wire EDM machine. The cross-sections of the wire-cut blocks were then mounted. Subsequently, the cross-sections of the coating were smoothed using sandpaper with grits of 400#, 600#, 800#, 1000#, 1200#, 1500#, 2000#, and 3000#. Mechanical polishing was then performed until no scratches were visible under a microscope. Finally, the samples were etched using a solution with a volume ratio of concentrated HNO3:concentrated HCl = 1:3. Preliminary microstructure observation of the etched metallographic samples was conducted using an OLYMPUS GX41 metallographic microscope. The microstructure of the sample after metallographic analysis and wear test was observed using a ZEISS Gemini 300 thermal field emission scanning electron microscope, which confirmed that the prepared coating was a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating.

[0017] In summary, the beneficial effects of this invention are as follows: This invention prepares a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating on the surface of high-speed steel using laser cladding technology; since the substrate material and the coating are metallurgically bonded, they exhibit good bonding strength. Simultaneously, the C element in the substrate penetrates into the coating and combines with the strong carbon element Nb to form NbC particles, which can improve the hardness and wear resistance of the coating to a certain extent. Furthermore, the Fe-Cr type BCC solid solution phase itself also exhibits high hardness and wear resistance. Therefore, this invention has great potential in the field of surface modification of high-speed steel cutting tools, and can significantly extend the service life of high-speed cutting tools and reduce manufacturing costs.

[0018] To obtain coatings with high hardness and high toughness at both room temperature and high temperature, a carbide-reinforced AlFeCrMoNb coating was designed using laser cladding technology and the infinite solid solution method. x (x=0.4, 0.6, 0.8) Two-phase BBC+Lavs nanosheet two-phase eutectic high-entropy alloy coating. Nb is a strong carbide-forming element, which combines with carbon that enters the molten pool due to partial melting of the substrate surface during laser cladding, synthesizing fine and dispersed carbides in situ to improve the hardness and wear resistance of the coating. The mixing enthalpy between Fe-Nb atomic pairs is relatively negative, and they easily form intermetallic compounds; while in the Fe-Cr-Mo system, the mixing enthalpy between atomic pairs is very close to zero, and they easily interact to form BCC disordered solid solutions. In view of the above characteristics, this invention successfully prepared a single-phase BCC solid solution high-entropy alloy coating in three steps. Step 1: Using an analytical electronic balance with an accuracy of 0.1 mg, weigh Al, Fe, Cr, Mo, and Nb powders respectively in a molar ratio of 1:1:1:x (x=0.4, 0.6, 0.8) and mix them. Step 2: Place the prepared powder into a dried stainless steel ball mill jar and mix it evenly using a planetary ball mill before spreading it on the surface of a high-speed steel substrate. Step 3: Use a fiber laser to melt the powder according to the set path and laser parameters. After the powder melts and solidifies, a "BCC+Laves nanosheet biphase eutectic high-entropy alloy coating" with good interfacial bonding with the substrate is obtained. Attached Figure Description

[0019] Figure 1 SEM micrographs of AlFeCrMoNbx (x = 0.4, 0.6, 0.8) high-entropy alloy coatings are shown. (a) and (f) are micrographs when x = 0.4, (b) and (e) are micrographs when x = 0.6, and (c) and (d) are micrographs when x = 0.8. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in further detail below, but the present invention is not limited to these embodiments. Any improvements or substitutions based on the basic spirit of these embodiments shall still fall within the scope of protection claimed by the claims of the present invention.

[0021] Example 1

[0022] Weigh out 10.7g of Al powder, 19.40g of Cr powder, 20.84g of Fe powder, 35.80g of Mo powder, 13.8g of Nb powder, and 800g of stainless steel balls. Place them in a planetary ball mill jar and ball mill for 2 hours at 300 r / min. Place the ball-milled powder in a 40mm×15mm×12mm mold on a high-speed steel plate. Pour the powder into the mold with a spoon and scrape it until it is level with the mold. Turn on the fiber laser and use a circular spot with a diameter of Φ=4mm under the set laser parameters: P=1800W, v=5mm / s, laser focal length 300mm. Perform single-pass cladding along the set path. After cooling, a single-phase BCC solid solution high-entropy alloy coating is obtained on the surface of the high-speed steel.

[0023] Example 2

[0024] Weigh out 9.42g of Al powder, 18.14g of Cr powder, 19.49g of Fe powder, 33.48g of Mo powder, 19.45g of Nb powder, and 800g of stainless steel balls. Place them in a planetary ball mill jar and ball mill for 2 hours at 300 r / min. Place the ball-milled powder in a mold with dimensions of 40mm×15mm×12mm on a high-speed steel plate. Pour the powder into the mold with a spoon and scrape it until it is flat with the mold. Turn on the fiber laser and use a circular spot with a diameter of Φ=4mm under the set laser parameters: P=1800W, v=5mm / s, laser focal length 300mm. Perform single-pass cladding according to the set path. After cooling, a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating with a pre-eutectic BCC phase is obtained on the surface of the high-speed steel.

[0025] Example 3

[0026] Weigh out 8.84g of Al powder, 17.04g of Cr powder, 18.3g of Fe powder, 31.44g of Mo powder, 24.36g of Nb powder, and 800g of stainless steel balls. Place them in a planetary ball mill jar and ball mill for 2 hours at 300 r / min. Place the ball-milled powder in a 40mm×15mm×12mm mold on a high-speed steel plate. Pour the powder into the mold with a spoon and scrape it until it is level with the mold. Turn on the fiber laser and use a circular spot with a diameter of Φ=4mm under the set laser parameters: P=1800W, v=5mm / s, laser focal length 300mm. Perform single-pass cladding along the set path. After cooling, a BCC+Laves nanosheet biphase eutectic high-entropy alloy coating is obtained on the surface of the high-speed steel.

Claims

1. A BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating, characterized in that, The composition of the alloy coating, in molar ratio, is: Al:Fe:Cr:Mo:Nb = 1:1:1:1:x, x = 0.6, 0.

8.

2. The BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating as described in claim 1, characterized in that, The BCC phase and the Laves phase in the alloy coating form a lamellar structure; the BCC phase is mainly Fe-Cr solid solution, and the Laves phase is mainly Fe2Nb.

3. A controllable preparation method for the BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating as described in claim 1, characterized in that, Includes the following steps: (1) Ingredient mixing: Weigh the corresponding weight of alloy powder according to the proportion and put it into the ball mill jar. Then add stainless steel balls with a mass of 8 times that of the alloy powder and ball mill in a high-energy planetary ball mill for 1.5-2.5 hours at a speed of 300 r / min. (2) Forming the blank: Place a mold with dimensions of 40mm×15mm×12mm on a high-speed steel plate: Pour the powder after ball milling in step (1) into the mold with a spoon and scrape it until it is level with the mold; (3) Cladding: A circular spot with a diameter of Φ=4mm is used to perform single-pass cladding according to the set path; (4) Quenching: The coated sample is quenched in water to obtain an ultrafine nanosheet eutectic structure.

4. The controllable preparation method of the BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating as described in claim 3, characterized in that, The alloy powder has an average particle size of 150-300 mesh.

5. The controllable preparation method of the BCC+Laves nanosheet dual-phase eutectic high-entropy alloy coating as described in claim 3, characterized in that, The cladding laser parameters are: P = 1800W, v = 5mm / s, and laser focal length 300mm.

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