Al2O3atTiC particle reinforced high-entropy alloy coating with in-situ authigenic core-shell structure and preparation method of Al2O3atTiC particle reinforced high-entropy alloy coating

Abstract

The invention belongs to the technical field of laser cladding surface modification, and relates to an in-situ authigenic core-shell structure Al2O3 (at) TiC particle reinforced high-entropy alloy coating and a preparation method thereof.The preparation method comprises the following steps that S1, elemental metal mixed powder is prepared, specifically, the elemental metal mixed powder comprises Al powder, Co powder, Cr powder, Ni powder and Ti powder; s2, the mixed powder prepared in the step S1 is subjected to ball milling, and preset composite powder is obtained; and S3, under the condition that protective gas is introduced into the surface of a base body, the preset composite powder obtained in the step S2 is subjected to cladding on the surface of the base body through a laser cladding technology, and the in-situ authigenic core-shell structure Al2O3-coated TiC particle reinforced high-entropy alloy coating is obtained. According to the Al2O3atTiC particle reinforced high-entropy alloy coating with the in-situ authigenic core-shell structure, the hardness and wear resistance of the alloy coating are effectively improved, and the purposes of improving the use performance of a matrix and prolonging the service life are achieved.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding surface modification technology, specifically relating to an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating and its preparation method. Background Technology

[0002] In recent years, high-entropy alloys (HEAs) composed of multiple elements in equimolar or near-equimolar ratios have become a research hotspot in the field of materials science, and have been extensively and deeply studied, thanks to the synergistic effects of their unique high-entropy effect, slow diffusion effect, lattice distortion effect, and "cocktail" effect. They exhibit comprehensive performance advantages such as high strength, high hardness, high-temperature stability, and excellent corrosion resistance and wear resistance.

[0003] AlCoCrFe series high-entropy alloys are one of the most widely studied typical systems in the field of high-entropy alloys. Their core components are Al, Co, Cr, and Fe. By introducing a fifth (or more) element (such as Ni, Ti, Mn, Cu, Si, etc.) to regulate composition and properties, diverse alloy derivative systems have been formed. AlCoCrFe series high-entropy alloy coatings achieve a good balance between performance and cost, and have broad application potential. To further synergistically improve the mechanical strength and surface wear resistance of AlCoCrFe series high-entropy alloy coatings, researchers at home and abroad have explored various improvement strategies focusing on composition design, process optimization, and microstructure control. In existing research, Liang Aimin et al. (patent publication number CN119243071A) mixed AlCoCrFeNi high-entropy alloy powder with chromium (Cr) powder and prepared a coating using high-velocity vapor deposition (HVOF) technology, achieving excellent wear resistance. Patent publication number CN119243072A discloses a method of mixing AlCoCrFeNi high-entropy alloy powder with nickel-coated carbon (Ni / C) powder and preparing a self-lubricating coating using high-velocity oxygen fuel (HVOF) spraying technology, which also achieves good friction reduction and wear resistance. Wu Kaiming et al. (patent publication number CN116356215A) added trace amounts of lanthanum (La) to an AlCrFeNiTi high-entropy alloy and prepared a bulk alloy through vacuum arc melting, achieving the research objective of simultaneously improving hardness, wear resistance, and corrosion resistance. Summary of the Invention

[0004] To improve the wear resistance of AlCoCrFe series high-entropy alloy coatings, this invention utilizes laser cladding technology to develop an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating and its preparation method. This effectively improves the hardness and wear resistance of the AlCoCrFeNiTi high-entropy alloy coating, thereby enhancing the performance of the substrate and extending its service life.

[0005] The specific technical solution is as follows:

[0006] A method for preparing an in-situ self-generated core-shell structured Al2O3@TiC particle-reinforced high-entropy alloy coating includes the following steps:

[0007] S1. Preparation of elemental metal mixed powder: The elemental metal mixed powder includes Al powder, Co powder, Cr powder, Ni powder, and Ti powder;

[0008] S2. The mixed powder prepared in step S1 is ball-milled to obtain the pre-formulated composite powder;

[0009] S3. Under the condition of introducing a protective gas into the substrate surface, the pre-placed composite powder obtained in step S2 is clad onto the substrate surface using a laser cladding process to obtain an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating.

[0010] In step S3, the carbon content in the matrix is ​​0.1~0.6wt%, and the iron content is 90.00~99.00wt%.

[0011] This invention utilizes laser cladding technology to fuse uniformly mixed high-entropy alloy powder onto the surface of a substrate, and uses the diffusion of Fe elements in the substrate to prepare an AlCoCrFeNiTi high-entropy alloy coating, which contains in-situ self-generated core-shell structured Al2O3@TiC particles.

[0012] Preferably, in step S1, the purity of the Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 99.4%~99.9%, and the particle size is 50~200μm; the molar ratio of the Al powder, Co powder, Cr powder, Ni powder, and Ti powder is (0.6~1):(0.7~1.6):(0.5~1.2):(0.7~1.5):(0.6~1).

[0013] Preferably, in step S2, the ball milling time is 3~7 hours and the rotation speed is 150~300 r / min.

[0014] Preferably, in step S3, the substrate is carbon steel or medium carbon alloy steel, more preferably H13 mold steel, Q235 steel, or 45 steel. The present invention does not have special requirements regarding the specific dimensions or specifications of the substrate.

[0015] Preferably, in step S3, the flow rate of the protective gas is 8-20 L / min, and the protective gas is preferably nitrogen or argon. Even with the protective gas introduced, a small amount of air remains in the environment around the substrate surface. During laser cladding, the oxygen in the air directly contacts the high-temperature molten pool. Laser heating raises the temperature of the molten pool to several thousand degrees Celsius, providing sufficient energy for the oxidation reaction. Aluminum powder reacts with oxygen in the air to form alumina in situ. Compared to directly adding alumina particles, the in-situ alumina bonds more tightly to the substrate, resulting in superior properties such as hardness in the alloy coating.

[0016] Preferably, in step S3, the laser cladding is performed with the following parameters: laser power of 0.6~1.9kW, scanning speed of 180~380mm / min, powder feeding amount of 15~30g / min, and overlap rate of 30%~50%.

[0017] Preferably, step S3 further includes substrate surface pretreatment, which includes substrate surface cleaning and sandblasting. The cleaning is preferably performed with anhydrous ethanol, which removes oil stains from the substrate surface. The abrasive used in the sandblasting process preferably has a particle size of 0.2~1.2 mm.

[0018] In another aspect, the present invention provides an in-situ self-generated core-shell structured Al2O3@TiC particle-reinforced high-entropy alloy coating, comprising Al a Co b Cr c Fe d Ni e Ti f High-entropy alloy coating and in-situ self-generated core-shell structured Al2O3@TiC particles; wherein Al a Co b Cr c Fe d Ni e Ti f In the high-entropy alloy coating, the molar ratio of each element a:b:c:d:e:f = (0.6~1):(0.7~1.6):(0.5~1.2):(0.5~1):(0.7~1.5):(0.6~1).

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention optimizes powder ratios and laser process parameters, using Al2O3 as a "seed" to enable TiC to heterogeneously nucleate and epitaxially grow, forming composite ceramic particles with Al2O3 as the core and TiC as the shell. This achieves in-situ generation of core-shell structured Al2O3@TiC particles. TiC encapsulates Al2O3 to form a precipitated strengthening phase, which plays a role in dispersion strengthening in the coating. At the same time, the high hardness of TiC and Al2O3 itself can resist the cutting action of wear particles, thereby improving the performance of the coating, and thus improving the performance of the substrate and extending its service life. Attached Figure Description

[0021] Figure 1 The images show the optical microscopy characterization results of the alloy coatings prepared in Examples 1-3 in different regions.

[0022] Figure 2 a is a scanning electron microscope image of the alloy coating prepared in Example 3. Figure 2 a1 is Figure 2 A magnified view of part of a. Figure 2 b-2h are the elemental distribution diagrams of Al, Co, Cr, Fe, Ni, Ti, and C of the alloy coating prepared in Example 3, respectively.

[0023] Figure 3 a is a transmission electron microscope image of the alloy coating prepared in Example 3. Figure 3 b-3i are the elemental distribution diagrams of Al, Co, Cr, Fe, Ni, Ti, C, and O in a local area of ​​the alloy coating prepared in Example 3;

[0024] Figure 4 Comparison of cross-sectional hardness of the alloy coatings prepared in Examples 1-3;

[0025] Figure 5 a-5b are the friction coefficient curves and wear morphology diagrams of the 45 steel substrate and the prepared alloy coating in Example 3, respectively. Detailed Implementation

[0026] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0027] Example 1

[0028] An in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating, including Al1Co 0.7 Cr1Fe 0.5Ni1Ti1 high-entropy alloy coating and in-situ self-generated core-shell structured Al2O3@TiC particles;

[0029] The preparation method includes the following steps:

[0030] S1. Preparation of elemental metal mixed powder: The elemental metal mixed powder includes Al powder, Co powder, Cr powder, Ni powder, and Ti powder; the purity of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 99.9%, and the particle size is 50 μm; the molar ratio of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 1:0.7:1:1:1;

[0031] S2. The mixed powder prepared in step S1 is ball-milled at a speed of 300 r / min for 3 hours to obtain the pre-formulated composite powder.

[0032] S3. H13 mold steel with a diameter of 100mm × 50mm × 20mm was selected as the substrate. The surface was first cleaned with anhydrous ethanol to remove surface oil. Then, the substrate surface was sandblasted using abrasive with a particle size of 0.2mm. Subsequently, argon gas was introduced onto the substrate surface at a flow rate of 10L / min. A laser cladding process was used to clad the pre-prepared composite powder obtained in step S2 onto the substrate surface. The laser power was 1.6kW, the scanning speed was 300mm / min, the powder feed rate was 15g / min, and the overlap rate was 35%, resulting in an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating. The chemical composition of the H13 mold steel substrate is shown in Table 1 below.

[0033] Table 1 Chemical composition of H13 steel (wt.%)

[0034] chemical composition Cr Mo V C Mn Si P S Fe content 4.96 1.25 1.12 0.40 0.33 0.89 0.01 0.01 margin

[0035] Example 2

[0036] An in-situ self-generated core-shell structured Al2O3@TiC particle-reinforced high-entropy alloy coating, comprising Al1Co1Cr1Fe 0.5 Ni 0.8 Ti1 high-entropy alloy coating and in-situ self-generated core-shell structure Al2O3@TiC particles;

[0037] The preparation method includes the following steps:

[0038] S1. Preparation of elemental metal mixed powder: The elemental metal mixed powder includes Al powder, Co powder, Cr powder, Ni powder, and Ti powder; the purity of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 99.5%, and the particle size is 100μm; the molar ratio of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 1:1:1:0.8:1;

[0039] S2 The mixed powder prepared in step S1 is ball-milled at a speed of 200 r / min for 5 hours to obtain the pre-formulated composite powder.

[0040] S3. A 100mm×50mm×20mm Q235 steel substrate was selected. The surface was first cleaned with anhydrous ethanol to remove oil stains, and then sandblasted using 0.8mm abrasive. Subsequently, argon gas was introduced onto the substrate surface at a flow rate of 12L / min. A laser cladding process was used to clad the pre-prepared composite powder obtained in step S2 onto the substrate surface. The laser power was 1.3kW, the scanning speed was 250mm / min, the powder feed rate was 30g / min, and the overlap rate was 40%, resulting in an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating. The chemical composition of the Q235 steel substrate is shown in Table 2 below.

[0041] Table 2 Chemical composition of Q235 steel (wt.%)

[0042] chemical composition C Mn Si P S Fe content 0.22 0.60 0.26 0.01 0.02 margin

[0043] Example 3

[0044] An in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating, comprising an Al1Co1Cr1Fe1Ni1Ti1 high-entropy alloy coating and in-situ self-generated core-shell structure Al2O3@TiC particles;

[0045] The preparation method includes the following steps:

[0046] S1. Preparation of elemental metal mixed powder: The elemental metal mixed powder includes Al powder, Co powder, Cr powder, Ni powder, and Ti powder; the purity of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 99.4%, and the particle size is 200 μm; the molar ratio of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 1:1:1:1:1;

[0047] S2 The mixed powder prepared in step S1 is ball-milled at a speed of 150 r / min for 7 hours to obtain the pre-formulated composite powder.

[0048] S3. A 100mm×50mm×20mm 45 steel substrate was selected. The surface was first cleaned with anhydrous ethanol to remove oil stains, and then sandblasted using 1.2mm abrasive. Subsequently, argon gas was introduced onto the substrate surface at a flow rate of 15L / min. A laser cladding process was used to clad the pre-prepared composite powder obtained in step S2 onto the substrate surface. The laser power was 0.9kW, the scanning speed was 200mm / min, the powder feed rate was 25g / min, and the overlap rate was 45%, resulting in an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating. The chemical composition of the 45 steel substrate is shown in Table 3 below.

[0049] Table 3 Chemical composition of 45 steel (wt.%)

[0050] chemical composition C Cr Ni Mn Si Cu Fe content 0.45 0.25 0.30 0.50 0.17 0.25 margin

[0051] test

[0052] The in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coatings prepared in Examples 1-3 were wire-cut to obtain test samples of 10mm×10mm×5mm; then the test samples were ground and polished using 240# sandpaper.

[0053] The in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coatings prepared in Examples 1-3 were characterized using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. Figure 1 The images show the optical microscopy characterization results of the alloy coatings prepared in Examples 1-3 in different regions, denoted as H13, Q235, and 45, respectively. As shown in the figures, the microstructure and morphology of the high-entropy alloy coatings prepared using different substrates in Examples 1-3 are basically consistent, with granular precipitates evenly distributed on the surface of the microstructure (the top, middle, and bottom regions in the figures refer to the upper, middle, and lower regions of the alloy coating). Figure 2 a is a scanning electron microscope image of the alloy coating prepared in Example 3. Figure 2 a1 is Figure 2 A magnified view of part of a. Figure 2 bh represents the elemental distribution of Al, Co, Cr, Fe, Ni, Ti, and C in the alloy coating prepared in Example 3. As shown in the figure, the precipitated particles in the alloy coating prepared in Example 3 are core-shell structured Al2O3@TiC. Figure 3 a is a transmission electron microscope image of the alloy coating prepared in Example 3. Figure 3b-3i are the elemental distribution diagrams of Al, Co, Cr, Fe, Ni, Ti, C, and O in a local area of ​​the alloy coating prepared in Example 3, respectively. As can be seen from the figure, Al2O3@TiC is a regular near square shape, which is a typical core-shell heterostructure. The Al2O3 particles are spherical core phases with a particle size of 0.35 μm, and are surrounded by a continuous and uniform TiC shell phase.

[0054] The cross-sectional hardness of the alloy coatings prepared in Examples 1-3 (referred to as H13, Q235, and 45# respectively) was tested using a microhardness tester, and the results are as follows: Figure 4 As shown. The cross-sectional hardness of the alloy coating prepared in Example 1 is 767.4 HV. 0.2 The alloy coating prepared in Example 2 has a hardness of 772.6 HV. 0.2 The alloy coating prepared in Example 3 has a hardness of 780.5 HV. 0.2 The results showed that the hardness of the alloy coatings prepared on the surfaces of H13 steel, Q235 steel and 45 steel did not differ significantly, proving the universality of the method.

[0055] Friction and wear tests were conducted on the 45 steel substrate and the prepared alloy coating (denoted as AlCoCrFeNiTi) from Example 3 using a friction and wear testing machine. The load was 100 N. The friction coefficient curve and wear morphology are shown below. Figure 5 As shown in a-5b, calculations show that the wear rate of the AlCoCrFeNiTi alloy coating prepared in Example 3 is 2.1 × 10⁻⁶. 5 mm·m -1 N -1 Compared to 45 steel matrix (3.7×10), 5 mm·m -1 N -1 The wear resistance of the substrate was reduced by 43%, significantly enhancing its anti-wear properties.

[0056] The alloy coating prepared by this invention has a good macroscopic morphology, contains core-shell structured Al2O3@TiC particles, and exhibits good hardness and friction properties.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an in-situ self-generated core-shell structured Al2O3@TiC particle-reinforced high-entropy alloy coating, characterized in that, Includes the following steps: S1. Preparation of elemental metal mixed powder: The elemental metal mixed powder includes Al powder, Co powder, Cr powder, Ni powder, and Ti powder; S2. The mixed powder prepared in step S1 is ball-milled to obtain the pre-formulated composite powder; S3. Under the condition of introducing a protective gas into the substrate surface, the pre-placed composite powder obtained in step S2 is clad onto the substrate surface using a laser cladding process to obtain an in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating. In step S3, the carbon content in the matrix is ​​0.1~0.6wt% and the iron content is 90.00~99.00wt%.

2. The preparation method according to claim 1, characterized in that, In step S1, the purity of the Al powder, Co powder, Cr powder, Ni powder, and Ti powder is 99.4%~99.9%, and the particle size is 50~200μm.

3. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of Al powder, Co powder, Cr powder, Ni powder, and Ti powder is (0.6~1):(0.7~1.6):(0.5~1.2):(0.7~1.5):(0.6~1).

4. The preparation method according to claim 1, characterized in that, In step S2, the ball milling time is 3~7 hours and the rotation speed is 150~300 r / min.

5. The preparation method according to claim 1, characterized in that, In step S3, the substrate is carbon steel or medium carbon alloy steel.

6. The preparation method according to claim 1, characterized in that, In step S3, the flow rate of the protective gas is 8~20 L / min.

7. The preparation method according to claim 1, characterized in that, In step S3, the laser cladding is specifically performed with the following parameters: laser power of 0.6~1.9kW, scanning speed of 180~380mm / min, powder feeding amount of 15~30g / min, and overlap rate of 30%~50%.

8. The preparation method according to claim 1, characterized in that, Step S3 also includes substrate surface pretreatment; the pretreatment includes substrate surface cleaning and sandblasting.

9. The in-situ self-generated core-shell structure Al2O3@TiC particle-reinforced high-entropy alloy coating prepared by any one of the preparation methods described in claims 1 to 8, characterized in that, Including Al a Co b Cr c Fe d Ni e Ti f High-entropy alloy coating and in-situ self-generated core-shell structure Al2O3@TiC particles; Among them, Al a Co b Cr c Fe d Ni e Ti f In the high-entropy alloy coating, the molar ratio of each element a:b:c:d:e:f = (0.6~1):(0.7~1.6):(0.5~1.2):(0.5~1):(0.7~1.5):(0.6~1).

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