A method for preparing a laser-clad shell-core heterostructure precipitated phase-enhanced composite coating

Abstract

This invention discloses a method for preparing a laser-clad shell-core heterostructure precipitated phase-reinforced composite coating, belonging to the fields of surface engineering and laser modification technology. This method uses nano-TiN particles to reinforce Fe... 50 Mn 30 Co 10 Cr 10 High-entropy alloy composite powder is used as a cladding powder. Laser-fed powder cladding is employed to modify the surface of a stainless steel substrate, addressing the problems of monolithic microstructure, poor interfacial compatibility, and insufficient mechanical stability in existing surface modification layers. Under the instantaneous high temperature and rapid solidification conditions of the molten pool, a TiN phase is induced to form in the coating. Further formation of the MnTi₂O₄ phase and a 9R transition structure occurs under the influence of Mn element segregation, local oxygen participation, and non-equilibrium phase transformation, resulting in a TiN-based MnTi₂O₄-9R shell-core heterostructure precipitate-reinforced coating. The prepared coating exhibits a clear multiphase hierarchical structure, good interfacial bonding characteristics, and high mechanical stability, making it suitable for improving the crack resistance and service stability of metal surfaces.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering and laser modification technology, specifically relating to a method for preparing a laser-clad shell-core heterostructure precipitated phase-enhanced composite coating. Background Technology

[0002] Stainless steel, due to its excellent corrosion resistance, machinability, and comprehensive mechanical properties, is widely used in key components in aerospace, petrochemical, and power equipment industries. As high-end equipment evolves towards higher loads, longer lifespans, and multi-condition operation, corrosion, wear, thermal cycling, and alternating stresses couple on the material surface, making it a primary starting point for crack initiation and damage accumulation. The bottleneck in material performance is shifting from the overall matrix to the insufficient coordination between surface strength and toughness. Therefore, there is an urgent need for surface strengthening and toughening control of key metallic materials to improve the reliability and service life of critical components.

[0003] Laser cladding, as a typical surface strengthening technology, has advantages such as concentrated heating, low dilution rate, fast cooling rate, and strong metallurgical bonding with the substrate, enabling the preparation of high-performance functional coatings on metal substrates. Compared with methods such as magnetron sputtering, cold spraying, plasma spraying, and vapor deposition, laser cladding is more conducive to constructing fine-grained, non-equilibrium, and multiphase composite structures, thereby achieving controllability of microstructure and performance improvement.

[0004] For coating materials, ceramic particle-reinforced metal matrix composites have proven to be a promising advanced material system. Regarding the selection of the metal matrix, a novel alloying strategy involving four or more elements aimed at maximizing configurational entropy has opened up a new and prominent field of metallic materials: high-entropy alloys (HEAs). Compared to traditional alloys, HEAs exhibit four unique effects: high entropy, hysteretic diffusion, lattice distortion, and mixing, resulting in better mechanical properties and greater designability. TiN, as a typical high-hardness ceramic phase, possesses high thermal stability, hardness, wear resistance, and a low coefficient of friction, making it widely used in machine tool coatings and attracting significant attention as a reinforcing phase. However, relying solely on a single TiN hard phase for reinforcement often leads to problems such as localized stress concentration, insufficient interfacial compatibility, and toughness loss. Furthermore, when TiN and HEAs participate in cladding together, significant differences in linear expansion coefficients and wettability issues easily generate large residual stresses at the interface, leading to microcracks in the coating or spalling of the reinforcing phase. Furthermore, under extreme non-equilibrium conditions of high element segregation and rapid solidification, brittle phases or harmful impurities often precipitate at the interface between the matrix and the reinforcing phase, which disrupts the strength-toughness balance of the material and makes it difficult to achieve a synergistic improvement in hardness, toughness, and long-term structural stability. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-enhanced composite coating.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-enhanced composite coating, characterized in that it includes: High-purity Fe, Mn, Co, and Cr raw materials are vacuum melted to form an alloy melt, which is then broken and atomized in an inert gas atmosphere to form micro-droplets. The droplets are rapidly cooled and solidified to obtain pre-alloyed powder. Nano-TiN particles are mixed with pre-alloyed powder, ball-milled, and dried to obtain nano-TiN particle-reinforced HEAs composite powder; Polish, clean, and dry the stainless steel before use; Laser cladding equipment is used to clad the surface of stainless steel. Nano-TiN particle-reinforced HEAs composite powder is fed in. The composite powder melts synchronously with the stainless steel surface to form a molten pool. After the heat input is removed, it solidifies rapidly, and finally a dense composite cladding layer is formed on the stainless steel surface. This is the laser cladding TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure precipitated phase-reinforced composite coating.

[0009] In a preferred embodiment of the preparation method described in this invention, the atomic ratio of Fe, Mn, Co, and Cr is 50:30:10:10.

[0010] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the nano-TiN particles to the pre-alloyed powder is 1.5~2.5:98.5~97.5; the purity of the nano-TiN particles is ≥99.5%, and the particle size is 500nm.

[0011] As a preferred embodiment of the preparation method described in this invention, the pre-alloyed powder has an average particle size of 80 μm, a sphericity >95%, and other elemental impurities <0.1 wt.%.

[0012] In a preferred embodiment of the preparation method described in this invention, the ball milling speed is 200~400 rpm and the ball milling time is 1~3 h.

[0013] As a preferred embodiment of the preparation method described in this invention, the laser cladding process parameters are: laser power 1700~2000 W, scanning speed 420~540 mm / min, spot diameter 3 mm, powder feeding speed 18 g / min, and multi-track overlap rate 40%.

[0014] In a preferred embodiment of the preparation method described in this invention, the cladding treatment is performed under an argon protective gas atmosphere with a flow rate of 8-15 l / min and a pressure of 0.6-0.8 MPa.

[0015] As a preferred embodiment of the preparation method described in this invention, the feeding of nano-TiN particle-reinforced HEAs composite powder is carried out by feeding powder through a coaxial feeding nozzle and a dual-cylinder feeder at a working distance of 12-17 mm, wherein the laser spot size and powder profile width at the working distance are 3 mm and 2.5 mm, respectively.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase enhanced composite coating, characterized in that: in the shell-core heterostructure precipitated phase, TiN is the outer reinforcing phase, MnTi2O4 is the core phase, and the 9R structure is distributed between TiN and MnTi2O4, playing a role in structural stability and strain release.

[0017] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of laser cladding TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-enhanced composite coating.

[0018] Beneficial effects of this invention: (1) The ceramic-reinforced metal-based composite coating provided by the present invention is composed of TiN and Fe 50 Mn 30 Co 10 Cr 10 High-entropy alloy hybrid powder, obtained through laser cladding technology, can achieve high-quality composite coatings in situ on the surfaces of critical stainless steel components, forming a good metallurgical bond with the substrate. The resulting composite coatings are suitable for damage protection and service life extension of stainless steel and related metal components.

[0019] (2) Under laser induction, a TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure precipitate was formed in situ inside the composite coating, achieving a synergistic organizational design of the hard phase, transition phase, and core phase. This phase formation can fix oxygen atoms in the molten pool, suppress the formation of reactive pores, and make an additional contribution to reducing porosity. In addition, it leads to grain refinement when non-uniform nucleation occurs.

[0020] (3) The TiN phase provides high hardness strengthening, the 9R structure phase helps stabilize the shell and core structure and provide strain buffering, and the MnTi2O4 phase provides interface transition. It works synergistically with the dislocation slip, stacking fault, TRIP and TWIP of the matrix phase to maintain high dislocation storage and continuous work hardening, thereby improving the microstructure stability and mechanical stability of the coating. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 Fe obtained by the atomization method of this invention 50 Mn 30 Co 10 Cr 10 SEM images of the powder; Figure 2 This is a SEM image of the nano-TiN particle-reinforced HEAs composite powder of the present invention. Figure 3 This is a schematic diagram of the laser cladding process for preparing a metal coating according to Embodiment 1 of the present invention; Figure 4 Transmission electron microscopy images of the TiN-based MnTi2O4-9R shell-core heterostructure nanostructure of this invention, along with fast Fourier transform and high-resolution images of the interface in the corresponding regions. Figure 5 Line scan energy dispersive spectroscopy analysis of the nanostructure of this invention; Figure 6 This is a transmission electron micrograph of the nanostructure under high strain levels.

[0022] Figure 7 The results of single-channel X-ray microscopy computed tomography reconstruction of the coating in the comparative example are shown. Figure 8 The image shows the single-channel X-ray microscopy computed tomography reconstruction results of the nano-TiN-reinforced HEAs composite coating in Example 1. Figure 9The electron backscatter diffraction distribution and grain statistics of the coating in Comparative Example 1 are shown. Figure 10 The electron backscattering diffraction pattern and grain statistics of the nano-TiN-reinforced HEAs composite coating in Example 1 are shown.

[0023] Figure 11 This is a transmission electron microscope (TEM) image of the coating obtained in Comparative Example 2 of the present invention.

[0024] Figure 12 This is a morphology diagram of the coating obtained in Comparative Example 3 of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0029] Instruments used in the embodiments of this invention: Vacuum induction melting furnace: EIGA50 / 500 (Shenzhen Xinwei New Materials); Laser cladding equipment: Metal+® series, Nanjing Pfizer Optoelectronics Co., Ltd.; Tensile testing: INSTRON M5582 electronic tensile testing machine (Pohang University of Science and Technology); CT: Zeiss Xradia Context MicroCT (Jiangnan University); TEM equipment: FEI Talos F200X thermal field emission scanning transmission electron microscope (USA) - Central University of Finance and Economics New Materials Research Institute; EBSD equipment: Zeiss SIGMA 300 C-Nano backscattered electron diffractometer (Wuxi Vocational and Technical University).

[0030] The method for determining the mechanical properties of nano-TiN-reinforced HEAs composite coatings in this invention is as follows: Dog-bone shaped tensile specimens with a gauge length of 21 mm, a width of 8 mm, and a thickness of 1 mm are fabricated by line discharge machining and tested at room temperature using an electronic universal tensile testing machine at 10 °C. -3 s -1 The test was conducted at a constant strain rate.

[0031] Example 1 This embodiment provides a method for preparing a laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-enhanced composite coating, specifically including the following steps: (1) First, mix the high-purity Fe, Mn, Co, and Cr raw materials according to Fe 50 Mn 30 Co 10 Cr 10 The target atomic ratio ingredients are melted in a vacuum induction melting furnace to form a homogeneous alloy melt at a melting temperature of 1500℃. The melt is then discharged through a guide nozzle under an inert atmosphere, and atomized by high-speed inert gas to form numerous fine droplets. These droplets rapidly cool and solidify within the atomization tower, yielding a product such as... Figure 1 Near-spherical Fe 50 Mn 30 Co 10 Cr 10 The pre-alloyed powder has an average particle size of about 80 μm, a sphericity >95%, and other elemental impurities <0.1 wt.%.

[0032] (2) Nano-TiN particles with a purity ≥99.5% and a particle size of 500 nm are mixed with the prepared Fe 50 Mn 30 Co 10 Cr 10 High-entropy pre-alloyed powder was mixed in a mass ratio of 2 wt.% to 98 wt.% and placed in a ball mill; The mixed powder was subjected to intermittent ball milling at a speed of 300 rpm for 1.5 hours, with a powder to ball weight ratio of 1:2. The ball milling system was stopped every 15 minutes with a 5-minute interval to reduce the heat generated by the high-energy ball milling impact. The mixed powder was then dried in a drying oven at 100°C for 30 minutes to remove residual ethanol from the powder. The final obtained nano-TiN particle-reinforced HEAs composite powder is as follows: Figure 2 As shown, the particles still maintain a high degree of sphericity, and the nano-TiN particles are uniformly distributed on the surface of HEAs spherical powder.

[0033] (3) Select stainless steel as the base material. First, polish the surface of stainless steel to remove the surface oxide layer and impurities. The surface was then cleaned with an organic solvent and dried for later use. Laser cladding equipment was used to clad the stainless steel surface. The controlled process parameters were: laser power 2000W, scanning speed 420 mm / min, spot diameter 3 mm, powder feeding speed 18 g / min, and multi-track overlap rate 40%. Nano-TiN particle-reinforced HEAs composite powder was fed into the stainless steel surface through a coaxial feeding nozzle and a double-cylinder feeder at a working distance of 15 mm. The laser spot size and powder profile width at the working distance were 3 mm and 2.5 mm, respectively. The cladding process was carried out under argon protective gas with a gas flow rate of 10 l / min and a pressure of 0.8 MPa. Under laser irradiation, the fed composite powder melts synchronously with the stainless steel surface to form a molten pool, and then rapidly solidifies after the heat input is removed, ultimately forming a dense composite cladding layer on the stainless steel surface, such as... Figure 3 As shown, this is a laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase enhanced composite coating.

[0034] Example 2 This embodiment involves transmission electron microscopy analysis of the composite coating obtained in Example 1. Specifically: like Figure 4 As shown, bright-field TEM results indicate the presence of regular prismatic precipitates in the coating. Further fast Fourier transform analysis of each region reveals that the precipitates are composed of TiN phase, with MnTi2O4 phase forming in the local core region of the precipitates. A structural transition zone, namely the 9R phase, exists between the TiN phase and the surrounding region.

[0035] High-resolution transmission electron microscopy (HRTEM) results show a clear interface between the TiN phase and the FCC matrix, indicating a good crystallographic match between them. In another local region, direct contact between the TiN phase and the 9R structure phase is observed, with the 9R structure exhibiting distinct layered modulation characteristics. Furthermore, a stable interface exists between the MnTi₂O₄ and TiN phases, suggesting that the MnTi₂O₄ and TiN phases are not randomly aggregated but rather form a heterostructure with a clearly defined interface relationship.

[0036] During the cladding process, the TiN component undergoes partial melting and re-precipitation under the high-temperature environment of the molten pool. Simultaneously, Mn elements locally segregate and, with the participation of residual oxygen, promote the formation of the MnTi2O4 phase. At the nanoscale, the system tends to encapsulate the internal high-energy structure (the 9R region with high dislocation density) with a more stable, lower-interface-energy phase (TiN) to reduce the total interfacial energy. Due to the extremely high cooling rate of LC, the 9R phase does not have time to transform into the more stable FCC structure and is therefore retained internally, thus constructing a TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure precipitate phase in situ within the composite cladding layer.

[0037] Example 3 This embodiment involves elemental line scan analysis of the composite coating obtained in Example 1 along typical precipitated phases, such as... Figure 5 As shown, the results reveal that from the outermost to the central region, the following regions sequentially appear: FCC matrix region, TiN region, 9R transition region, TiN region, MnTi2O4 core region, 9R transition region, TiN region, and FCC matrix region. This line scan characteristic further confirms that the precipitated phase is not a single TiN particle, but rather a multi-layered shell-core heterogeneous nanostructure composed of a TiN outer layer, a MnTi2O4 core, and a 9R transition layer.

[0038] Example 4 This embodiment tests the tensile test of the nano-TiN particle-reinforced HEAs composite coating obtained in Example 1 at room temperature using an electronic universal tensile testing machine at 10°C. -3 s -1 A tensile test was conducted at a constant strain rate, specifically as follows: like Figure 6 The precipitated phase of the TiN-based MnTi2O4-9R shell-core heterostructure remained intact under high strain conditions, indicating that the heterostructure has a continuous contribution to the strength.

[0039] The shell-core heterostructure precipitates, as nanoscale reinforcing units, are dispersed in the FeMnCoCr high-entropy alloy cladding layer, which is beneficial to improving the microstructure stability, interface stability and surface service performance of the composite coating.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that step (2) is omitted, while the remaining steps are the same as in Example 1, that is, Fe is directly added. 50 Mn 30 Co 10 Cr 10 Pre-alloyed powder is melt-treated on the surface of stainless steel to obtain a coating without any reinforcing particles.

[0041] X-ray microscopy and computed tomography were used to reconstruct 3D distribution maps of the single-track coatings prepared in Example 1 and Comparative Example 1. Statistical analysis using Avizo software revealed that Fe without any reinforcing phase... 50 Mn 30 Co 10 Cr 10 The porosity of the high-entropy alloy coating is 1.3878%. Figure 7 The composite coating prepared in Example 1 had a porosity of 0.0395%. Figure 8 ).

[0042] In contrast, the addition of TiN significantly suppressed porosity during laser cladding. This is because the introduction of TiN and the subsequent in-situ precipitated phase preferentially form coordination bonds with oxygen atoms, significantly reducing oxygen activity in the local molten pool. This effectively prevents the occurrence of CO reaction at the chemical reaction source, thereby effectively suppressing the nucleation of reactive pores.

[0043] The coatings prepared in Example 1 and Comparative Example 1 were characterized by electron backscattering diffraction. Figure 9 Fe 50 Mn 30 Co 10 Cr 10 The high-entropy alloy coating exhibits a mixture of equiaxed and columnar grains, displaying CET behavior. Meanwhile, Fe... 50 Mn 30 Co 10 Cr 10 The average grain size of the high-entropy alloy coating is 39.43 μm. For the composite coating of the example (… Figure 10 The grain type is near-equiaxed grains with a grain size of 8.90 μm, indicating that the addition of TiN can effectively refine the grains.

[0044] This is because during the solidification process of the molten pool, most of the nano-TiN particles are distributed along the grain boundaries through the grain growth front. Due to the pinning effect, particles along the grain boundaries may hinder boundary movement, thereby limiting the grain growth rate. At the same time, some TiN particles and precipitated phases can serve as heterogeneous nucleation sites, promoting grain refinement.

[0045] Tensile tests were performed on the coated samples prepared in Example 1 and the comparative example, and the Fe obtained was... 50 Mn 30 Co 10 Cr 10 The ultimate tensile strength and elongation of the high-entropy alloy coating and the TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase reinforced composite coating are shown in Table 1.

[0046] Table 1 Tensile test results of the coatings in Comparative Example 1 and Example 1

[0047] As can be seen from Table 1, compared to Fe 50 Mn 30 Co 10 Cr 10 High-entropy alloy coatings, such as TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase reinforced composite coatings, can significantly improve strength without sacrificing too much elongation, thereby optimizing the combination of strength and plasticity.

[0048] This is due to the enhancement of precipitation strengthening and fine grain strengthening by the precipitated phase of the TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure, combined with Fe... 50 Mn 30 Co 10 Cr 10 The phase transformation-induced plasticity effect inherent in high-entropy alloys is organically combined to achieve a balance between strength and ductility.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that the nano-TiN particles and Fe in step (2) are added. 50 Mn 30 Co 10 Cr 10 The mass ratio of high-entropy pre-alloyed powder was replaced with 0.5 wt.% : 99.5 wt.%, and the remaining steps were the same as in Example 1. The resulting coating was as follows: Figure 11 As shown, it can be seen that it only has TiN and MnTi2O4 precipitates. The coating's ultimate tensile strength is 681 MPa and its elongation is 32.9%.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that the nano-TiN particles and Fe in step (2) are added. 50 Mn 30 Co 10 Cr 10 The mass ratio of the high-entropy pre-alloyed powder was replaced with 3 wt.% : 97 wt.%, and the remaining steps were the same as in Example 1. The resulting coating was as follows: Figure 12 As shown, this is due to the clustering effect, which prevents the formation of a shape.

[0051] In summary, this invention uses stainless steel as the substrate and a mixed powder composed of 2 wt.% TiN and 98 wt.% FeMnCoCr multi-principal-element high-entropy alloy as the cladding material to prepare a ceramic-based HEAs composite coating on the stainless steel surface based on laser cladding technology. Under high-energy laser induction, the mixed powder and the substrate surface melt synchronously to form a molten pool. Under the conditions of high temperature, convective mass transfer, and rapid solidification in the molten pool, TiN nanoparticles undergo partial melting, reprecipitation, and interface reconstruction. Simultaneously, Mn elements undergo local segregation and react with Ti and O, forming the MnTi2O4 phase in situ within the coating. The TiN phase encapsulates the 9R metastable phase, ultimately obtaining a composite coating containing a TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure precipitate.

[0052] In principle, the formation of the core-shell structure of this invention is essentially the result of thermodynamic and kinetic processes. The formation mechanism is as follows: under the high-temperature environment of the molten pool, the TiN component undergoes partial melting and re-precipitation, while Mn elements locally segregate and, with the participation of residual oxygen, promote the formation of the MnTi₂O₄ phase. The system tends to encapsulate the internal high-energy structure with the more stable TiN phase, while the extremely high cooling rate allows the metastable 9R phase to be retained. Therefore, as long as the molten pool temperature is sufficient to allow partial melting of TiN and the aforementioned reactions to occur, followed by rapid solidification, it is possible to form this structure.

[0053] The multi-principal high-entropy alloy of this invention is Fe 50 Mn 30 Co 10 Cr 10 This series of metastable alloys shares a high degree of elemental similarity with stainless steel, resulting in similar coefficients of thermal expansion. This is beneficial for reducing thermal mismatch during the cladding process and improving forming quality. Simultaneously, the alloy possesses low stacking fault energy, providing favorable thermodynamic conditions for the formation of the 9R phase.

[0054] The core of this invention's coating lies in the unique interfacial characteristics of the in-situ formed shell-core heterogeneous nanostructure. Analysis shows that a clear interface exists between the TiN phase and the FCC matrix, exhibiting good crystallographic matching. Under high strain conditions, the precipitated phase of this TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure remains intact, indicating that it is not a simple mechanical mixture, but rather that the 9R transition phase and the MnTi2O4 core work synergistically to optimize the interfacial chemical state and buffer stress. This design organically combines precipitation strengthening and grain refinement with the phase transformation-induced plasticity effect of FeMnCoCr high-entropy alloys, thus maintaining good plasticity while significantly improving strength.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a laser-clad shell-core heterostructure precipitated phase-enhanced composite coating, characterized in that: include, High-purity Fe, Mn, Co, and Cr raw materials are vacuum melted to form an alloy melt, which is then broken and atomized in an inert gas atmosphere to form micro-droplets. The droplets are rapidly cooled and solidified to obtain pre-alloyed powder. Nano-TiN particles are mixed with pre-alloyed powder, ball-milled, and dried to obtain nano-TiN particle-reinforced HEAs composite powder; Polish, clean, and dry the stainless steel before use; Laser cladding equipment is used to clad the surface of stainless steel. Nano-TiN particle-reinforced HEAs composite powder is fed in. The composite powder melts synchronously with the stainless steel surface to form a molten pool. After the heat input is removed, it solidifies rapidly, and finally a dense composite cladding layer is formed on the stainless steel surface. This is the laser cladding TiN-based MnTi2O4-9R shell-core heterogeneous nanostructure precipitated phase-reinforced composite coating.

2. The preparation method according to claim 1, characterized in that: The atomic ratio of Fe, Mn, Co, and Cr is 50:30:10:

10.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the nano-TiN particles to the pre-alloyed powder is 1.5~2.5:98.5~97.5; the purity of the nano-TiN particles is ≥99.5%, and the particle size is 500nm.

4. The preparation method according to claim 1, characterized in that: The pre-alloyed powder has an average particle size of 80 μm, a sphericity >95%, and other elemental impurities <0.1 wt.%.

5. The preparation method according to claim 1, characterized in that: The ball mill rotates at a speed of 200-400 rpm and the milling time is 1-3 hours.

6. The preparation method according to claim 1, characterized in that: The laser cladding process parameters are as follows: laser power 1700~2000 W, scanning speed 420~540 mm / min, spot diameter 3 mm, powder feeding speed 18 g / min, and multi-track overlap rate 40%.

7. The preparation method according to claim 1, characterized in that: The cladding process is carried out under an inert atmosphere, with a flow rate of 8~15 l / min and a pressure of 0.6~0.8 MPa.

8. The preparation method according to claim 1, characterized in that: The fed nano-TiN particle-reinforced HEAs composite powder is supplied through a coaxial feed nozzle and a dual-cylinder feeder at a working distance of 12-17 mm. The laser spot size and powder profile width at the working distance are 3 mm and 2.5 mm, respectively.

9. The laser-clad TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-reinforced composite coating prepared by the preparation method according to any one of claims 1 to 8, characterized in that: In the shell-core heterogeneous nanostructure precipitated phase, TiN is the outer reinforcing phase, MnTi2O4 is the core phase, and the 9R structure is distributed between TiN and MnTi2O4, playing a role in structural stability and strain release.

10. The application of the laser cladding TiN-based MnTi2O4-9R shell-core heterostructure precipitated phase-enhanced composite coating as described in claim 9.

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