In-situ synthesized multi-carbide reinforced high-entropy alloy coating and preparation method

Abstract

The application discloses an in-situ self-grown multi-carbide reinforced high-entropy alloy coating and a preparation method thereof. The cladding powder is selected from Al, Co, Cr, Ni, Nb, Ti, Zr and C powders, the particle size of the C powder is 325 mesh, the particle size of the remaining powders is 100-200 mesh, the molar ratio of the powders Al, Co, Cr, Ni, Nb, Ti, Zr and C is 1:1:1:1:1 / 3:1 / 3:1 / 3:1.5, and the pre-set powder on the base material is subjected to laser cladding. The parameters of the laser cladding are as follows: the power is 800-1500 W, the scanning speed is 10-25 mm / s, the spot diameter is 2-3 mm, and the overlapping rate is 20-50%. The special alloy powder and the laser cladding parameters can be used to in-situ self-grow multi-carbides, and effectively improve the hardness, wear resistance and high-temperature oxidation resistance of the high-entropy alloy coating and the Q235 steel base body.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy coating technology, and in particular to an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating and its preparation method. Background Technology

[0002] High-entropy alloys are novel multi-principal element alloys formed by combining five or more different elements, possessing a unique elemental composition compared to traditional alloys. Compared to traditional alloys, high-entropy alloys exhibit superior performance due to four main effects: high-entropy effect, lattice distortion effect, slow diffusion effect, and the "cocktail" effect. AlCoCrFeNi-based high-entropy alloys, as a widely used high-entropy alloy system, not only possess high hardness and strength but also good tunability. However, the development of extreme applications places higher demands on the performance of high-entropy alloys. The performance of ceramic-phase particle-reinforced metallic materials has been widely applied in industry. Their high hardness, high elastic modulus, low coefficient of friction, excellent chemical stability, and self-lubricating properties result in metal matrix composites with high strength, high modulus, excellent wear resistance, corrosion resistance, and a low coefficient of thermal expansion. Therefore, combining high-entropy alloys with ceramics to improve material performance has broad application prospects.

[0003] Laser cladding technology is widely used in the surface modification of materials, and can obtain high-performance cladding layers with good metallurgical bonding to the substrate. Compared with other processes, laser cladding technology has higher precision, controllability, efficiency, and relatively low heat input. Combining high-entropy alloys with laser cladding technology can produce laser-clad high-entropy alloy coatings, thereby improving the comprehensive mechanical properties of the material surface and expanding the application range of high-entropy alloys.

[0004] Current research on ceramic phases mainly focuses on binary ceramic reinforcing phases. However, the addition of binary ceramic phases has inherent drawbacks. First, there is a 'strength-toughness conflict' behavior. The added ceramic phase is a brittle material. Second, the difference in thermal expansion coefficients between the ceramic phase and the metal matrix easily leads to crack initiation at the phase interface, causing premature failure of the metal matrix composite. Traditional binary carbides have high melting points, but their high-temperature oxidation resistance is poor, limiting their potential applications in high-temperature environments.

[0005] A well-designed microstructure can significantly influence the wear resistance, corrosion resistance, and even toughness of a coating. Multi-component high-entropy alloying provides a new approach and method for achieving uniform elemental distribution at the atomic scale. This multi-component high-entropy concept, applied to the field of ceramic phases, involves adding multiple similar elements to an existing binary ceramic phase to form compounds with simple solid solution structures. Studies show that multi-component ceramic phases formed after metal-side multi-component alloying retain the basic properties of the original binary ceramic phase while significantly improving certain properties. The lattice disorder in multi-component ceramic phases may further enhance their physical and mechanical properties. Furthermore, compared to carbide-reinforced phases prepared by external methods, in-situ carbide-reinforced metal-matrix composite coatings exhibit stronger interfacial bonding between the carbide phase and the matrix, resulting in greater stability during service.

[0006] For example, high-entropy carbide ceramic (Ti,Zr,Hf,Nb,Ta)C powder was prepared by spark plasma sintering, and its oxidation resistance was better than that of the binary carbides that make up high-entropy carbide ceramics. (TiZrNbHfTa)N and (TiZrNbHfTa)C ceramic coatings prepared by reactive co-sputtering exhibited better corrosion resistance and a lower coefficient of friction than single-component ceramic phases. However, these results still do not meet the requirements of applications. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating with good wear resistance and its preparation method.

[0008] To address the aforementioned technical problems, a method for preparing an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating includes the following steps:

[0009] S1. Pretreatment of the substrate: The substrate is made of Q235 steel plate, which is polished to remove the oxide scale.

[0010] S2. Powder pretreatment: The cladding powders selected are Al, Co, Cr, Ni, Nb, Ti, Zr and C powders. The particle size of C powder is 325 mesh, and the particle size of the other powders is 100-200 mesh. The molar ratio of Al, Co, Cr, Ni, Nb, Ti, Zr and C powders is 1:1:1:1:1 / 3:1 / 3:1 / 3:1.5. All powders are mixed evenly.

[0011] S3, Pre-applied powder: Use a binder to evenly coat the alloy powder onto the substrate surface and then dry it;

[0012] S4. Laser cladding: Laser cladding is performed on pre-placed powder on the substrate. The parameters for laser cladding are: power 800-1500W, scanning speed 10-25mm / s, spot diameter 2-3mm, and overlap rate 20-50%.

[0013] Preferably, in step S3, an adhesive is used to uniformly coat the alloy powder onto the substrate surface, with a pre-layer thickness of 1 mm. After coating, the powder is air-dried and then oven-dried.

[0014] Preferably, in step S3, the drying temperature of the pre-formed layer is 80°C and the drying time is 2 hours.

[0015] Preferably, in step S1, the substrate surface is polished sequentially using 80#, 180#, 240#, 320#, 400#, 600#, and 800# SiC sandpaper. The polished substrate is then ultrasonically cleaned for 10-30 minutes and placed in a drying oven at 200°C for 0.5-2 hours.

[0016] Preferably, in step S2, the powder used is powder that has been dried in a vacuum drying equipment. The powder is mixed uniformly using a V-type powder mixer for 2 hours. The drying temperature of the vacuum drying equipment is 120°C and the drying time is 2 hours.

[0017] Preferably, in step S2, the purity of the powder is greater than 99.9%.

[0018] Preferably, in step S4, the parameters for laser cladding are: power 1000W, scanning speed 18mm / s, spot diameter 2mm, and overlap rate 30%.

[0019] The in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating of the present invention is prepared by any of the aforementioned in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating preparation methods.

[0020] The beneficial effects of this invention are as follows: This invention uses special alloy powder and laser cladding parameters to generate multi-component carbides in situ. The performance of high-entropy alloy coatings is improved by generating multi-component carbides in situ. The selection of C powder with a larger mesh size ensures sufficient reaction between alloy elements and C elements, which is beneficial to the generation and uniform distribution of carbides. The selection of powder particle size of the other selected elements is 100-200 mesh to improve powder flowability, reduce agglomeration, and obtain a high-entropy alloy coating with good shape and uniform performance.

[0021] This invention achieves a good combination of in-situ self-generated multi-component carbides and high-entropy alloys, effectively improving the hardness, wear resistance and high-temperature oxidation resistance of the high-entropy alloy coating and the Q235 steel substrate.

[0022] This invention applies the concept of multi-element high entropy to the field of ceramic phases. That is, by adding a variety of other elements similar to the original binary ceramic phase, a multi-element carbide with a simple solid solution structure can be formed, which greatly improves its performance.

[0023] The preparation process described in this invention is simple and easy to implement, which promotes the widespread application of high-entropy alloys in material surface engineering. Attached Figure Description

[0024] Figure 1 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 XRD diffraction pattern of high-entropy alloy coating.

[0025] Figure 2-1 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 Microstructure of high-entropy alloy coating.

[0026] Figure 2-2 For existing AlCoCrFeNiTiC 1.5 Microstructure of high-entropy alloy coating.

[0027] Figure 2-3 For the existing AlCoCrFeNiZrC 1.5 Microstructure of high-entropy alloy coating.

[0028] Figure 2-4 For existing AlCoCrFeNiNbC 1.5 Microstructure of high-entropy alloy coating.

[0029] Figure 2-5 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 Point scan diagram of multi-component carbides in high-entropy alloy coating.

[0030] Figure 3-1 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Microhardness distribution diagram of high-entropy alloy coating.

[0031] Figure 3-2 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC1.5 AlCoCrFeNiNbC 1.5 Average microhardness diagram of high-entropy alloy coating.

[0032] Figure 4 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Depth and width of wear marks on high-entropy alloy coatings and Q235 steel.

[0033] Figure 5 AlCoCrFeNi(NbTiZr)C provided as an example of the present invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Wear volume of high-entropy alloy coating and Q235 steel.

[0034] Figure 6 The AlCoCrFeNi(NbTiZr)C example provided by this invention 1.5 High-entropy alloy coatings with existing AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Oxidation weight gain curves of high-entropy alloy coatings and Q235 steel. Detailed Implementation

[0035] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art.

[0036] In this specific embodiment, an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating is prepared according to the following method:

[0037] Remove the oxide scale from the Q235 steel substrate by grinding. Use 80#, 180#, 240#, 320#, 400#, 600# and 800# SiC sandpaper to grind the substrate surface in sequence. Ultrasonic clean the ground substrate for 20 minutes, and then dry it in a drying oven at 200℃ for 1 hour.

[0038] Spherical Al, Co, Cr, Ni, Nb, Ti, Zr, and C powders were dried in a vacuum drying oven at 120℃ for 2 hours. They were then uniformly mixed in a molar ratio of 1:1:1:1:1 / 3:1 / 3:1 / 3:1.5 using a V-type powder mixer for 2 hours. The C powder had a particle size of 325 mesh, while the remaining powders had a particle size of 100-200 mesh.

[0039] The mixed powder was added to water glass and stirred until homogeneous. The mixture was then evenly coated onto the substrate surface to a pre-applied thickness of 1 mm. The coating was then allowed to air dry and subsequently dried. The drying temperature for the pre-applied layer was 80℃, and the drying time was 2 hours.

[0040] Laser cladding method: cladding was performed under the following conditions: power 1000W, scanning speed 18mm / s, spot diameter 2mm, protective gas flow rate 15L / min, defocusing distance 35mm, and overlap rate 30%. This yielded an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating, namely AlCoCrFeNi(NbTiZr)C. 1.5 High-entropy alloy coating.

[0041] Figure 1 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The XRD diffraction patterns of the high-entropy alloy coatings show that each coating consists of a BCC phase and a carbide phase, with AlCoCrFeNi(NbTiZr)C being the most prominent. 1.5 The carbides formed by the high-entropy alloy coating are multi-component carbides (NbTiZr)C.

[0042] The formation mechanism of the multi-component carbide (NbTiZr)C: Nb, Ti, and Zr are all high-melting-point, strong carbide-forming elements that can react with C to form stable binary carbides. Nb, Ti, and Zr have similar atomic radii, and their relative enthalpy of mixing is close to 0. Their respective binary carbides all have an FCC structure, ensuring the formation of a stable solid solution structure. Therefore, during laser cladding, under sufficient C source conditions, the three elements can react with C to form the solid solution structure of the multi-component carbide (NbTiZr)C.

[0043] Figure 2-1 , Figure 2-2 , Figure 2-3 , Figure 2-4 , Figure 2-5 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The microstructure of the high-entropy alloy coating and the point scan images corresponding to the multi-component carbides show that the size of the multi-component carbides is significantly finer than that of the binary carbides, ranging from only 41% to 83%.

[0044] Figure 3-1 and Figure 3-2 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The microhardness distribution and average microhardness diagram of the high-entropy alloy coating show that AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The average microhardness of the high-entropy alloy coatings were 940, 832, 875, and 970 HV, respectively, all of which were significantly higher than that of the Q235 substrate (200 HV), and approximately 4.18-4.86 times that of the substrate.

[0045] Figure 4 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Wear depth and width of high-entropy alloy coating and Q235 steel.

[0046] Figure 5 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 Wear volume of high-entropy alloy coating and Q235 steel.

[0047] Combination Figure 4-5 It can be seen that the wear depth, width, and wear volume of each high-entropy alloy coating are significantly lower than those of the Q235 substrate, indicating that the wear resistance of each high-entropy alloy coating is significantly better than that of the Q235 substrate. The calculated AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The wear rate of the coating was 1.56 × 10⁻⁶. -6 3.47×10 -6 2.26×10 -6 and 4.51×10 -6 mm 3 The wear rate of the Q235 matrix is ​​2.08 × 10⁻⁶ N·m. -5 mm 3 / (N·m), the wear resistance of each coating is approximately 4.62-13.33 times that of the Q235 substrate. Among them, AlCoCrFeNi(NbTiZr)C 1.5 It has the lowest wear rate and the strongest wear resistance, which is approximately equal to that of AlCoCrFeNiTiC. 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The coating is 1.44-2.89 times stronger. AlCoCrFeNi(NbTiZr)C 1.5 The reason for the strongest wear resistance of the coating is that an ideal, ordered crystal lattice is considered a dislocation waveguide with uniform resistance, where dislocation propagation is not reflected or dispersed. However, the disorder of the lattice in multi-component carbides alters this phenomenon; the non-uniform resistance to dislocation propagation results in energy reflection and dispersion, manifesting as resistance to plastic deformation caused by dislocations. Another important reason may be solid solution strengthening, where lattice distortion hinders dislocation movement or alters its slip system. Secondly, binary carbides improve the hardness and strength of metallic materials at the expense of toughness. The mismatch in the thermal expansion coefficients of the reinforcing phase particles and the matrix easily leads to the formation of internal cracks in the coating. However, by introducing multi-component carbide-forming elements to construct microstructures with different spatial configuration distribution behaviors, the coherent or semi-coherent interface matching between the reinforcing phase and the matrix, and between reinforcing phases themselves, facilitates load transfer and suppresses the susceptibility to crack initiation. Furthermore, the in-situ formation of finely dispersed second-phase particles plays a role in second-phase reinforcement and dislocation reinforcement, and also exhibits good strength and toughness. Therefore, AlCoCrFeNi(NbTiZr)C 1.5 High-entropy alloy coatings exhibit the strongest wear resistance.

[0048] Figure 6 AlCoCrFeNi(NbTiZr)C 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5Weight gain curves of high-entropy alloy coating and Q235 substrate after 50 hours of high-temperature oxidation. It can be seen that the mass gain of the high-entropy alloy coating increases parabolically with time. (AlCoCrFeNi(NbTiZr)C) 1.5 AlCoCrFeNiTiC 1.5 AlCoCrFeNiZrC 1.5 AlCoCrFeNiNbC 1.5 The mass gains after 50 hours of coating oxidation were 13.35, 20.24, 16.82, and 28.14 mg / cm³. -2 The mass gain of the Q235 matrix increased linearly with time, reaching 140.63 mg / cm² after 50 hours of oxidation. -2 The high-temperature oxidation resistance of each coating is approximately 5.01-10.57 times that of the Q235 substrate. Among them, AlCoCrFeNi(NbTiZr)C 1.5 The high-entropy alloy coating exhibits the lowest mass gain and the strongest resistance to high-temperature oxidation after 50 hours of high-temperature oxidation, approximately 1.26-2.11 times that of other coatings.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating, characterized in that: Includes the following steps: S1. Pretreatment of the substrate: The substrate is made of Q235 steel plate, which is polished to remove the oxide scale. S2. Powder pretreatment: The cladding powders selected are Al, Co, Cr, Ni, Nb, Ti, Zr and C powders. The particle size of C powder is 325 mesh, and the particle size of the other powders is 100-200 mesh. The molar ratio of Al, Co, Cr, Ni, Nb, Ti, Zr and C powders is 1:1:1:1:1 / 3:1 / 3:1 / 3:1.

5. All powders are mixed evenly. S3. Pre-applied powder: Use a binder to evenly coat the alloy powder onto the substrate surface and then dry it; S4. Laser cladding: Laser cladding is performed on the pre-placed powder on the substrate. The parameters of laser cladding are as follows: In step S4, the parameters of laser cladding are: power 1000W, scanning speed 18 mm / s, spot diameter 2 mm, and overlap rate 30%.

2. The method for preparing in-situ self-generated multi-component carbide-reinforced high-entropy alloy coatings according to claim 1, characterized in that: In step S3, an adhesive is used to uniformly coat the alloy powder onto the substrate surface, with a pre-layer thickness of 1 mm. After coating, the powder is air-dried and then oven-dried.

3. The method for preparing in-situ self-generated multi-component carbide-reinforced high-entropy alloy coatings according to claim 2, characterized in that: In step S3, the drying temperature of the pre-formed layer is 80°C and the drying time is 2 hours.

4. The method for preparing in-situ self-generated multi-component carbide-reinforced high-entropy alloy coatings according to claim 1, characterized in that: In step S1, the substrate surface is polished sequentially using 80#, 180#, 240#, 320#, 400#, 600# and 800# SiC sandpaper. The polished substrate is then ultrasonically cleaned for 10-30 minutes and then placed in a drying oven at 200℃ for 0.5-2 hours.

5. The method for preparing in-situ self-generated multi-component carbide-reinforced high-entropy alloy coatings according to claim 1, characterized in that: In step S2, the powder used is powder that has been dried in a vacuum drying equipment. The powder is mixed uniformly using a V-type powder mixer for 2 hours. The drying temperature of the vacuum drying equipment is 120℃ and the drying time is 2 hours.

6. The method for preparing an in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating according to claim 1, characterized in that: In step S2, the purity of the powder is greater than 99.9%.

7. A high-entropy alloy coating reinforced by in-situ self-generated multi-component carbides, characterized in that: It is prepared by any one of the in-situ self-generated multi-component carbide-reinforced high-entropy alloy coating preparation methods as described in claims 1-6.

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