Nickel-based alloy surface laser cladding coating and preparation method thereof

Abstract

The invention discloses a nickel-based alloy surface laser cladding coating and a preparation method thereof, and belongs to the technical field of alloy coating preparation. The preparation method of the nickel-based alloy surface laser cladding coating comprises the following steps that MoNiSi / La2O3 powder is subjected to ball milling, and pretreated powder is obtained; the nickel-based alloy base material is subjected to solid solution aging heat treatment, cleaned and dried, and a pretreated base material is obtained; and a binding agent and the pretreated powder are mixed and then laid on the surface of the pretreated base material for laser cladding, then aging heat treatment is conducted, and the nickel-based alloy surface laser cladding coating is obtained. According to the nickel-based alloy surface laser cladding coating, the surface hardness, wear resistance and service stability are greatly improved while the high-temperature strength and toughness of a nickel-based alloy matrix are kept, the service life of key parts such as a turbine disc tenon connection structure can be remarkably prolonged when the nickel-based alloy surface laser cladding coating is applied to the key parts, and the application prospect is wide.

Description

Technical Field

[0001] This invention belongs to the field of alloy coating preparation technology, specifically relating to a laser cladding coating on a nickel-based alloy surface and its preparation method. Background Technology

[0002] Nickel-based superalloy GH4169 (Inconel 718) is widely used in critical components of aero-engines, such as turbine disks, blades, and falcon joints, due to its excellent high-temperature strength, oxidation resistance, and creep resistance. However, in actual service, these components are often subjected to complex environments of high temperature, high-speed friction, and alternating loads. The turbine disk falcon joint structure, in particular, is highly susceptible to surface wear, crack initiation, and propagation due to intense fretting friction and cyclic contact stress, thus shortening the component's service life. Existing GH4169 matrix materials still suffer from insufficient surface hardness, degraded wear resistance, and a high coefficient of friction under these extreme conditions, making it difficult to meet the high reliability and long service life requirements of next-generation aero-engines.

[0003] To improve the service performance of GH4169 alloy surfaces, scholars and engineers both domestically and internationally have conducted research on various surface modification and coating strengthening processes. For example, traditional nitriding and carburizing processes can improve surface hardness to some extent, but the coating thickness is limited, and its high-temperature stability is poor, easily degrading under conditions above 600 °C. Physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods can obtain dense films, but their deposition rates are low, coating adhesion is insufficient, and it is difficult to achieve large-area uniform coverage on complex morphological components. Thermal spraying processes can produce controllable coating thickness, but the bonding interface has porosity and non-metallurgical bonding, making it prone to peeling during service, limiting its application in high-load areas. In contrast, laser cladding technology has advantages such as high energy density, fast cooling rate, and strong metallurgical bonding, enabling the rapid construction of wear-resistant coatings on GH4169 surfaces, making it a more ideal strengthening method currently available. However, existing laser cladding coating processes still have several shortcomings: on the one hand, coarse columnar crystals and segregation structures are easily formed during the cladding process, resulting in insufficient coating toughness; on the other hand, insufficient softening and strengthening phase precipitation in the heat-affected zone (HAZ) will weaken the mechanical properties of the bonding area between the substrate and the coating, making it easy to become a weak link in service failure.

[0004] Enhancing the overall service performance of coatings and improving their wear resistance and stability to effectively solve the problem of shortened lifespan caused by surface failure in key components such as turbine disk joints is one of the research hotspots in this field. Summary of the Invention

[0005] The problem to be solved by this invention is to provide a laser cladding coating on the surface of a nickel-based alloy and its preparation method, so as to solve the problems of poor mechanical property matching between the nickel-based alloy substrate and the surface coating, poor wear resistance and stability, and insufficient coating toughness.

[0006] The technical solution adopted to solve the technical problem is to provide a method for preparing a laser cladding coating on a nickel-based alloy surface, including the following steps: (1) Ball mill the MoNiSi / La2O3 powder to obtain the pretreated powder; (2) The nickel-based alloy substrate is subjected to solution aging heat treatment and then cleaned and dried to obtain a pretreated substrate; (3) After mixing the binder with the pretreatment powder, the mixture is laid on the surface of the pretreatment substrate for laser cladding, and then subjected to aging heat treatment to obtain a laser cladding coating on the surface of the nickel-based alloy.

[0007] Preferably, the mass ratio of Mo, Ni, Si and La2O3 in the MoNiSi / La2O3 powder is (41~42): (32~33): (23~24.5): (0.5~4).

[0008] More preferably, the mass ratio of Mo, Ni, Si and La2O3 in the MoNiSi / La2O3 powder is 41.7: 32.84: 24.46: 1.

[0009] Preferably, the ball milling in step (1) includes the following steps: placing grinding steel balls and MoNiSi / La2O3 powder in a ball mill jar and loading it onto a planetary ball mill, introducing inert gas and then revolving around the planet while rotating on its own axis.

[0010] More preferably, the mass ratio of grinding steel balls to MoNiSi / La2O3 powder is (8~12):1; the revolution speed is 80~120 rpm; the rotation speed is 180~220 rpm, with a pause of 5~10 min every 25~35 min of rotation; and the ball milling time is 4~6 h.

[0011] More preferably, the mass ratio of grinding steel balls to MoNiSi / La2O3 powder is 10:1; the revolution speed is 100 rpm; the rotation speed is 200 rpm, with a 5-minute pause every 30 minutes of rotation; and the ball milling time is 5 hours.

[0012] Preferably, the nickel-based alloy substrate in step (2) is GH4169 nickel-based alloy substrate; the solution aging heat treatment includes the following steps: the nickel-based alloy substrate is solution treated at 950~970℃ for 0.5~1.5 h, air quenched, and then aged at 700~740℃ for 7.5~8.5 h, and after aging, it is cooled to 600~640℃ at a cooling rate of 45~55℃ / h and held for 7.5~8.5 h, and then air cooled to room temperature.

[0013] More preferably, the solution aging heat treatment includes the following steps: the nickel-based alloy substrate is solution treated at 960°C for 1 hour, air-quenched, and then aged at 720°C for 8 hours. After aging, the temperature is lowered to 620°C at a cooling rate of 50°C / h and held for 8 hours, and then air-cooled to room temperature.

[0014] Preferably, the binder in step (3) is polyvinyl alcohol; the volume ratio of the binder to the pretreated powder is (1~2):(1~2).

[0015] More preferably, the volume ratio of binder to pretreated powder is 1:1.

[0016] Preferably, in step (3), the laser power of laser cladding is 1600~2000 W, the scanning speed is 10~20 mm / s, the laser spot diameter is 3~5 mm, and the overlap rate is 45~55%.

[0017] More preferably, in step (3), the laser power of laser cladding is 1800 W, the scanning speed is 15 mm / s, the laser spot diameter is 5 mm, and the overlap rate is 50%.

[0018] More preferably, the laser cladding thickness is 1 mm.

[0019] Preferably, the aging heat treatment in step (3) includes the following steps: heating the pretreated substrate that has undergone surface laser cladding to 275-325°C at a heating rate of 4-6°C / min, then heating it to 675-725°C at a heating rate of 8-12°C / min, holding it at that temperature for 3.5-4.5 h, and then air cooling it to room temperature.

[0020] More preferably, the aging heat treatment in step (3) includes the following steps: heating the pretreated substrate that has undergone surface laser cladding to 300°C at a heating rate of 5°C / min, then heating it to 700°C at a heating rate of 10°C / min, holding it at that temperature for 4 hours, and then air cooling it to room temperature.

[0021] The present invention also provides a laser cladding coating on a nickel-based alloy surface prepared by the above-mentioned method for preparing a laser cladding coating on a nickel-based alloy surface.

[0022] The present invention has the following beneficial effects: (1) The Mo-Ni-Si hard silicide is stably present in the laser cladding coating on the nickel-based alloy surface of the present invention, and finely dispersed γ′-Ni3(Al, Ti) is precipitated after aging, realizing the dual strengthening of "hard silicide + coherent precipitate phase". Compared with the traditional single strengthening mechanism, the coating of the present invention has the advantages of high hardness and matrix precipitation strengthening.

[0023] (2) The hardness of the laser cladding coating on the nickel-based alloy surface of the present invention is significantly improved, which effectively avoids the problem of severe softening of the heat-affected zone in the traditional cladding process.

[0024] (3) In the process of preparing the laser cladding coating on the nickel-based alloy surface of the present invention, the aging treatment improves the nanohardness of the cladding layer, the heat-affected zone and the substrate. At the same time, the wear resistance index increases significantly in each region, which improves the resistance to crack initiation and propagation, far exceeding that of single alloy cladding coatings.

[0025] (4) The wear resistance of the laser cladding coating on the nickel-based alloy surface of the present invention is significantly improved, the wear rate is low, the depth and width of the wear marks are small, the surface morphology is smoother, and it exhibits excellent wear resistance.

[0026] (5) The reliability of the laser cladding coating on the nickel-based alloy surface of the present invention is improved. By eliminating the problem of excessive performance gradient between the coating and the substrate, the mechanical property matching degree of the three regions of cladding layer, heat-affected zone and substrate is improved, and the risk of interface stress concentration and early wear failure is effectively reduced.

[0027] (6) The laser cladding coating on the surface of nickel-based alloys of the present invention significantly improves the surface hardness, wear resistance and service stability while maintaining the high temperature strength and toughness of the nickel-based alloy substrate. It can significantly extend the service life of key components such as turbine disk falcon connection structure, reduce maintenance and replacement costs, and has obvious engineering application advantages and industrialization value. Attached Figure Description

[0028] Figure 1The images show SEM images and elemental EDS surface scans of the MoNiSi alloy powder and MoNiSi / La2O3 powder obtained in Example 1 of this invention; wherein, (a) is the SEM image of the MoNiSi alloy powder; (b) is the SEM image of the MoNiSi / La2O3 powder; (c) is the EDS surface scan of the Mo element in the MoNiSi alloy powder; (d) is the EDS surface scan of the Si element in the MoNiSi alloy powder; and (e) is the EDS surface scan of the Ni element in the MoNiSi alloy powder. (f) is an EDS surface scan of O element in MoNiSi alloy powder; (g) is an EDS surface scan of Mo element in MoNiSi / La2O3 powder; (h) is an EDS surface scan of Si element in MoNiSi / La2O3 powder; (i) is an EDS surface scan of Ni element in MoNiSi / La2O3 powder; (j) is an EDS surface scan of O element in MoNiSi / La2O3 powder; (k) is an EDS surface scan of La element in MoNiSi / La2O3 powder. Figure 2 These are optical microstructure images of the clad and aged samples in different regions of the present invention; wherein, (a) is an optical microstructure image of the matrix region of the clad sample; (b) is an optical microstructure image of the fusion line region of the clad sample; (c) is an optical microstructure image of the cladding layer region of the clad sample; (d) is an optical microstructure image of the matrix region of the aged sample; (e) is an optical microstructure image of the fusion line region of the aged sample; and (f) is an optical microstructure image of the cladding layer region of the aged sample. Figure 3 These are XRD patterns of the samples in the cladding state and after aging treatment according to the present invention; Figure 4 This is a spot scan image of the cladding layer region of the cladding sample of the present invention; Figure 5 This is a Vickers hardness distribution diagram of the cross-section of the cladding state and the sample after aging treatment according to the present invention; Figure 6 This paper compares the nanoindentation performance of samples in the cladding state and after aging treatment at three locations: the cladding layer, the heat-affected zone, and the substrate. (a) represents nanohardness; (b) represents elastic recovery parameter; (c) represents maximum loading depth; (d) represents H / E value; and (e) represents H... 3 / E 2 Value; (f) represents the contact flexibility; Figure 7 The images show SEM images of nano-scratches in the cladding layer and substrate region of the cladding sample of the present invention; where (a) is the cladding layer region; (b) is the substrate region; (c) is a high-magnification SEM image of the middle part of the scratch in the cladding layer region; and (d) is a high-magnification SEM image of the end of the scratch in the cladding layer region. Figure 8The images show the three-dimensional morphology and depth curve analysis of the nano-scratches in the cladding layer region of the sample after aging treatment according to the present invention; wherein, (a) is a surface morphology image of the nano-scratches; (b) is a three-dimensional schematic diagram of the nano-scratches; and (c) is a scratch depth curve. Figure 9 The figures show the scratch depth curves of the cladding state and the sample after aging treatment according to the present invention; wherein, (a) is the cladding layer region of the cladding state sample; (b) is the cladding layer region of the sample after aging treatment; (c) is the heat-affected zone of the cladding state sample; (d) is the heat-affected zone of the sample after aging treatment; (e) is the substrate region of the cladding state sample; and (f) is the substrate region of the sample after aging treatment. Figure 10 The images show the surface morphology, three-dimensional morphology, and corresponding wear depth curves of the reciprocating friction and wear pattern; wherein, (a) is the surface morphology of the GH4169 substrate under reciprocating friction and wear; (b) is the three-dimensional morphology of the GH4169 substrate under reciprocating friction and wear; (c) is the wear depth curve of the GH4169 substrate; (d) is the surface morphology of the cladding sample under reciprocating friction and wear pattern of the present invention; (e) is the three-dimensional morphology of the cladding sample under reciprocating friction and wear pattern of the present invention; (f) is the wear depth curve of the cladding sample under reciprocating friction and wear pattern of the present invention; (g) is the surface morphology of the sample after aging treatment under the present invention; (h) is the three-dimensional morphology of the sample after aging treatment under the present invention; and (i) is the wear depth curve of the sample after aging treatment under the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of this invention, and not all of them.

[0030] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but only to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0032] Example 1 A method for preparing a laser cladding coating on a nickel-based alloy surface includes the following steps: (1) Mo, Ni, and Si are mixed to form MoNiSi alloy powder and then mixed with La2O3. The mass ratio of Mo, Ni, Si and La2O3 is 41.7: 32.84: 24.46: 1 to obtain MoNiSi / La2O3 powder. Then, 600 g of grinding steel balls and 60 g of MoNiSi / La2O3 powder are placed in a ball mill jar and loaded onto a planetary ball mill. After argon gas is introduced, the mill rotates at a speed of 100 rpm and rotates at a speed of 200 rpm. During the rotation, the mill pauses for 5 minutes every 30 minutes. The milling time is 5 hours to obtain pretreated powder. (2) The GH4169 nickel-based alloy substrate was solution treated at 960℃ for 1 h, air quenched and then aged at 720℃ for 8 h. After aging, it was cooled to 620℃ at a cooling rate of 50℃ / h and held for 8 h. It was then air-cooled to room temperature. The GH4169 nickel-based alloy substrate was ultrasonically cleaned 3 times with anhydrous ethanol and its surface oxide layer was removed with 180-2000 mesh SiC sandpaper. After ultrasonic cleaning and drying with anhydrous ethanol, the pretreated substrate was obtained. (3) Polyvinyl alcohol is used as a binder and mixed with pretreatment powder at a volume ratio of 1:1 and then laid on the surface of the pretreatment substrate for laser cladding. The thickness is 1 mm. The laser power of laser cladding is 1800 W, the scanning speed is 15 mm / s, the laser spot diameter is 5 mm, and the overlap rate is 50%. After laser cladding, the pretreatment substrate that has undergone surface laser cladding is heated to 300℃ at a heating rate of 5℃ / min, and then heated to 700℃ at a heating rate of 10℃ / min. It is kept at this temperature for 4 h and then air-cooled to room temperature to obtain the laser cladding coating on the nickel-based alloy surface.

[0033] Example 2 A method for preparing a laser cladding coating on a nickel-based alloy surface includes the following steps: (1) Mo, Ni, and Si are mixed to form MoNiSi alloy powder and then mixed with La2O3. The mass ratio of Mo, Ni, Si and La2O3 is 41:32:23:4 to obtain MoNiSi / La2O3 powder. Then, 480 g of grinding steel balls and 60 g of MoNiSi / La2O3 powder are placed in a ball mill jar and loaded onto a planetary ball mill. After argon gas is introduced, the ball mill rotates at a speed of 80 rpm and rotates at a speed of 180 rpm. During the rotation, the ball milling is paused for 5 minutes every 25 minutes. The ball milling time is 4 hours to obtain pretreated powder. (2) The GH4169 nickel-based alloy substrate was solution treated at 950℃ for 1.5 h, air quenched, and then aged at 700℃ for 8.5 h. After aging, it was cooled to 640℃ at a cooling rate of 45℃ / h and held for 7.5 h. It was then air-cooled to room temperature. The GH4169 nickel-based alloy substrate was ultrasonically cleaned 3 times with anhydrous ethanol, and its surface oxide layer was removed with 180-2000 mesh SiC sandpaper. After ultrasonic cleaning and drying with anhydrous ethanol, the pretreated substrate was obtained. (3) Polyvinyl alcohol is used as a binder and mixed with pretreatment powder at a volume ratio of 1:2 and then laid on the surface of the pretreatment substrate for laser cladding. The thickness is 1 mm. The laser power of laser cladding is 1600 W, the scanning speed is 10 mm / s, the laser spot diameter is 5 mm, and the overlap rate is 45%. After laser cladding, the pretreatment substrate that has undergone surface laser cladding is heated to 275°C at a heating rate of 4°C / min, and then heated to 725°C at a heating rate of 8°C / min. The temperature is maintained for 3.5 h, and then air-cooled to room temperature to obtain the laser cladding coating on the nickel-based alloy surface.

[0034] Example 3 A method for preparing a laser cladding coating on a nickel-based alloy surface includes the following steps: (1) Mo, Ni, and Si are mixed to form MoNiSi alloy powder and then mixed with La2O3. The mass ratio of Mo, Ni, Si and La2O3 is 24:33:24.5:0.5 to obtain MoNiSi / La2O3 powder. Then, 720 g of grinding steel balls and 60 g of MoNiSi / La2O3 powder are placed in a ball mill jar and loaded onto a planetary ball mill. After argon gas is introduced, the mill rotates at a speed of 120 rpm and rotates at a speed of 220 rpm. During the rotation, the mill pauses for 10 min every 35 min. The ball milling time is 6 h to obtain pretreated powder. (2) The GH4169 nickel-based alloy substrate was solution treated at 970℃ for 0.5 h, air quenched, and then aged at 740℃ for 7.5 h. After aging, it was cooled to 600℃ at a cooling rate of 55℃ / h and held for 8.5 h. It was then air-cooled to room temperature. The GH4169 nickel-based alloy substrate was ultrasonically cleaned 3 times with anhydrous ethanol, and its surface oxide layer was removed with 180-2000 mesh SiC sandpaper. After ultrasonic cleaning and drying with anhydrous ethanol, the pretreated substrate was obtained. (3) Polyvinyl alcohol is used as a binder and mixed with pretreatment powder at a volume ratio of 2:1 and then laid on the surface of the pretreatment substrate for laser cladding. The thickness is 1 mm. The laser power of laser cladding is 2000 W, the scanning speed is 20 mm / s, the laser spot diameter is 3 mm, and the overlap rate is 55%. After laser cladding, the pretreatment substrate that has undergone surface laser cladding is heated to 325℃ at a heating rate of 6℃ / min, and then heated to 675℃ at a heating rate of 12℃ / min. The temperature is held for 4.5 h and then air-cooled to room temperature to obtain the laser cladding coating on the nickel-based alloy surface.

[0035] Comparative Example 1 A method for preparing a laser cladding coating on a nickel-based alloy surface, which differs from the preparation method in Example 1 in that: the pretreated substrate that has undergone laser cladding treatment in step (3) is not subjected to aging heat treatment, and the remaining steps and parameters are the same as in Example 1.

[0036] Test case The pretreated substrate that underwent surface laser cladding in step (3) of Example 1 was wire-cut to obtain a test sample with a size of 1 cm × 1 cm × 1 cm, and then subjected to aging heat treatment for performance testing; the pretreated substrate that underwent surface laser cladding in step (3) of Comparative Example 1 was wire-cut to obtain a test sample with a size of 1 cm × 1 cm × 1 cm for performance testing.

[0037] 1. Microstructure and Phase Analysis The cladding state sample (Comparative Example 1) and the aged sample (Example 1) were embedded in epoxy resin and polished sequentially using SiC sandpaper ranging from 180 mesh to 2000 mesh. Subsequently, the polished surfaces were etched using CuSO4 reagent. The microstructure of different regions of the sample cross-section was observed using an optical microscope (OM). The phase composition of the cladding layer was analyzed by X-ray diffraction (XRD) using a Cu target Kα beam scan at a scanning range of 10°–90° and a scanning rate of 4° / min. The morphology of the MoNiSi / La2O3 mixed powder and the scratch morphology of the cladding layer were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in secondary electron (SE) mode. The results are as follows: Figures 1-4 As shown in Table 1.

[0038] from Figure 1As can be seen, the MoNiSi alloy powder and MoNiSi / La2O3 powder obtained in Example 1 are both granular with uniform particle size distribution, and the elements are well distributed in the micro-regions. Mo and Si elements are uniformly distributed in the mixed powder without obvious agglomeration. Ni and La elements show a certain degree of enrichment in local areas, but do not form agglomerates or continuous segregation structures, and the overall micro-dispersion remains good. This distribution characteristic is conducive to forming a coating structure with uniform structure and reasonable distribution of reinforcing phases during the subsequent cladding process. This indicates that the mixed powder has good uniformity and stability, providing a basic guarantee for the compact structure and elemental uniformity of the subsequent laser cladding coating.

[0039] Figure 2 This study demonstrates the optical microstructure evolution characteristics of laser-clad and age-treated samples in different regions (matrix, fusion line, and cladding layer). Figure 2 As seen in a and 2d, the matrix (BM) region exhibits an equiaxed crystal structure with uniform grain size and clear grain boundaries, indicating that the cladding process had a limited impact on the matrix structure. After aging treatment, the grain outlines became slightly sharper, with slight refinement in local areas, indicating that the aging process promoted the stability of the microstructure. Figure 2 As shown in b and 2e, in the fusion line (FL) region, the clad sample exhibits a transition from coarse columnar crystals to equiaxed crystals in the matrix, with obvious microstructural discontinuities and grain coarsening. In contrast, the aged sample shows a smoother grain transition in this region, with a denser columnar crystal arrangement and a significantly narrower interface transition zone, indicating that heat treatment can effectively improve the microstructural compatibility between the cladding layer and the matrix, reducing the risk of thermal stress concentration at the interface. Figure 2 As shown in 2c and 2f, in the cladding layer (CL) region, both groups of samples exhibit a typical columnar crystal structure growing along the heat flow direction. However, after aging treatment, the size of the columnar crystals is significantly reduced, the grains are more dense and uniform, and the dendrite spacing is reduced. Figure 2 Combination Figure 3 It can be seen that this microstructural evolution is related to the dispersed precipitation of the strengthening phase and the release of residual stress, which helps to improve the microstructural stability and crack resistance of the coating. In summary, aging treatment significantly improves the uniformity and density of the microstructure of the laser cladding layer and the heat-affected zone, providing an microstructural basis for improving its mechanical properties and service reliability.

[0040] from Figure 3 As can be seen, the diffraction peaks of the clad sample mainly correspond to intermetallic compounds and silicide phases, including MoNi, Ni2Si, MoSi2, MoNi4, Ni3Si2, MoNiSi and Mo2Ni3Si. At the same time, the γ-(Ni,Fe) matrix phase and a small amount of Laves-Fe2Nb phase were detected.

[0041] The SEM morphology of the cladding layer (CL) region of the cladding sample was performed by point scanning, as shown in the figure. Figure 4 As shown, the corresponding EDS element point scanning results are shown in Table 1.

[0042] Table 1 Elemental composition analysis at EDS points Combination Figure 4 As shown in Table 1, the interdendritic regions (such as P1, P2, P3, P5, and P6) are enriched with Ni, Mo, and Si elements, and also contain a certain amount of Nb and Cr. This is consistent with the Mo–Ni–Si hard silicides (such as MoNi, Ni2Si, MoNiSi, and MoSi2) detected by XRD, indicating that these regions are mainly composed of high-hardness intermetallic compounds. In contrast, the bulk region (P4) contains higher Fe and Cr contents, while the Ni, Mo, and Si contents are significantly reduced, which is speculated to be a Fe and Cr-rich γ-(Ni,Fe) solid solution phase. The small amount of Al and Ti elements detected may be dissolved in the γ matrix or exist as γ′ phase forming elements. Overall, the EDS results reveal obvious elemental segregation characteristics in the cladding layer, reflecting that a Mo-Ni-Si-rich hard phase network is preferentially formed between the dendrites during solidification, while the γ matrix phase is dominant within the dendrites, providing a multi-scale strengthening basis for subsequent mechanical properties.

[0043] Combination Figures 3-4 As shown in Table 1, the presence of hard silicides in the clad sample is related to EDS spot scan analysis ( Figure 4 The results were consistent with those of the previous study, which showed enrichment of Ni, Mo, and Si elements in the interdendritic regions (P1–P3, P5, P6), indicating segregation-driven formation of Mo–Ni–Si ternary silicides during solidification. The high Fe and Cr content in the bulk region (P4) can be attributed to the Cr-rich γ-(Ni,Fe) solid solution. The intensity of the γ'-Ni3(Al,Ti) diffraction peak in the aged sample prepared after aging at 700°C was significantly enhanced compared to the cladding state. This is consistent with the Nb-rich region and small amounts of Al and Ti elements detected by EDS spot scanning, which are typical γ′ phase-forming elements. These coherent strengthening phases precipitated in the γ matrix can effectively improve the load-bearing capacity of the matrix and enhance its resistance to plastic deformation. Furthermore, the Mo–Ni–Si silicides remained stable after aging, indicating that the interdendritic silicide network can still provide high hardness and wear resistance in subsequent use. Therefore, the strengthening mechanism of the aged coating can be summarized as "dual strengthening": on the one hand, the stable hard silicides existing between dendrites provide structural support and wear resistance; on the other hand, the precipitation of the γ′ phase brings significant matrix precipitation strengthening. This multi-scale synergistic effect can significantly improve the high-temperature strength and wear resistance of the coating.

[0044] 2 Mechanical property testing Mechanical properties were tested on the cladding state (Comparative Example 1) and the aged state (Example 1) samples. Test locations were in three regions: the cladding layer (CL), the heat-affected zone (HAZ), and the matrix region (BM). Microhardness testing was performed using a Vickers microhardness tester under a load of 300 gf and a hold time of 15 s. Nanoindentation and scratch testing were conducted on different micro-regions using a Nano Test Vantage platform equipped with a Berkovich indenter of standard geometry. Nanoindentation was performed at least six times independently on each micro-region under consistent conditions: a loading time of 20 s and a maximum load of 350 mN. Nanoscratching was performed twice on each micro-region, with a scratch length of 100 μm and a maximum load of 350 mN. Friction and wear tests were conducted using a reciprocating sliding method, with a load of 10 N, a single-pass wear length of 4 mm, a sliding speed of 8 mm / s, and a test duration of 30 min. Results are as follows: Figures 5-10 As shown.

[0045] Firstly, regarding the Vickers hardness distribution across the cross section, from... Figure 5 As can be seen, in the cladding layer (CL) region, the hardness after aging treatment is significantly higher than that in the cladding state, with the average hardness increasing from 462 HV to 548 HV. This is mainly due to the precipitation and dispersion of the γ′ strengthening phase during heat treatment, as well as the stable existence of the Mo–Ni–Si hard phase. In the heat-affected zone (HAZ), the hardness of the cladding state sample drops significantly to a minimum of approximately 240 HV, while the average hardness of the aged state remains at approximately 420 HV, indicating that heat treatment effectively suppresses the softening phenomenon in this region. This is closely related to the retention of the γ′-Ni3(Al,Ti) phase detected by XRD. The hardness difference between the two states in the matrix (BM) region is relatively small, approximately 420~440 HV, indicating that heat treatment has a limited impact on the matrix. Overall, aging heat treatment not only improves the hardness of the cladding layer but also improves the mechanical property gradient in the transition zone between the cladding layer and the matrix, which helps to enhance the overall wear resistance and service stability.

[0046] Further comparative analysis of the nanoindentation properties of the cladding state and the aged sample at three locations—the cladding layer (CL), the heat-affected zone (HAZ), and the substrate (BM)—was conducted, and the results are as follows: Figure 6 As shown. From Figure 6As can be seen, aging treatment increased the nanohardness of the three regions by 41.1%, 61.5%, and 57.1%, respectively, with the HAZ showing the largest increase. This indicates that significant precipitation of strengthening phases (such as the γ′ phase) occurred during aging, resulting in a markedly denser microstructure. The increase in elastic recovery parameters (43.5–63.6%) further demonstrates the enhanced ability of the material to store elastic energy and the reduced proportion of plastic deformation. Simultaneously, the maximum loading depth decreased by approximately 13–18% at all three locations, indicating enhanced resistance to plastic deformation after aging. H / E and H 3 / E 2 H and E are two commonly used comprehensive mechanical property indicators in nanoindentation and wear resistance analysis, where H is nanohardness and E is elastic modulus. H / E is typically used to measure a material's ability to resist plastic deformation under elastic strain. 3 / E 2 The H / E value and Hd value are durability parameters that measure a material's overall resistance to plastic deformation and indentation. 3 / E 2 The value increased significantly in all regions, especially in the H2Z region. 3 / E 2 The increase reached 332%, demonstrating that aging treatment significantly improved the material's resistance to crack initiation and propagation, which is of great significance for improving the wear life of the coating. Although the contact flexibility increased by 20-30%, the combined hardness and H... 3 / E 2 The improved properties of this "soft yet not weak" coating help disperse contact stress and reduce stress concentration at the interface. Overall, aging treatment not only simultaneously improves the strength-toughness balance between the cladding layer and the substrate, but also significantly enhances the mechanical properties of the heat-affected zone, thus laying the foundation for improved overall wear resistance and service reliability.

[0047] Furthermore, from Figure 7 As can be seen, the CL scratch grooves are shallower and more continuous, with only a small amount of material pile-up and local shear bands at the groove edges. Although there are some debris at the scratch ends, no large-scale spalling occurs, indicating stronger damage resistance under a 350 mN load. In contrast, the scratch grooves in the BM region are significantly deeper, with more severe material removal at the edges and larger debris accumulation at the ends, reflecting its greater susceptibility to plastic failure under frictional stress. Combined with mechanical parameters, the CL exhibits higher H / E and HB values. 3 / E 2 The value indicates that the cladding layer has superior elastic recovery and crack propagation resistance when subjected to external loads, and possesses stronger service stability.

[0048] The three-dimensional morphology and depth curve analysis of the nano-scratches in the cladding layer region were performed, and the results are as follows: Figure 8 As shown. Surface morphology ( Figure 8 a) and three-dimensional profile ( Figure 8 b) Both indicate that the scratches are accompanied by localized material buildup at the beginning and end, but the bottom of the groove is flat and continuous, with no obvious through cracks; the depth curve ( Figure 8 c) The maximum indentation depth of each scratch is similar, and the stable depth is relatively low, indicating that the cladding layer has a stable load-bearing capacity during the scratching process. Combined with the aforementioned XRD results, it can be seen that the reinforcing phases such as MoSi2, Mo2Ni3Si, and γʹ formed in the cladding layer collectively improve the hardness. Figure 5 This inhibits plastic flow and fatigue crack propagation, thereby giving the cladding layer superior wear resistance compared to the substrate.

[0049] The scratch depth curves of the cladding state and the 700℃ aged state at the cladding layer (CL), heat-affected zone (HAZ), and substrate (BM) were analyzed, and the results are as follows: Figure 9 As shown. From Figure 9 As can be seen, in both the cladding and aged states, the scratch depth curves at all three locations show a significant instantaneous increase in the initial stage, followed by a stabilization. This is related to the rapid plastic deformation during the initial loading stage of the scratch. Compared to the cladding state, the overall scratch depth of the aged sample in the CL, HAZ, and BM regions is significantly reduced, and the fluctuation amplitude is smaller, indicating that aging treatment effectively improves the material's resistance to plastic deformation and surface uniformity. Among them, the CL region of the aged sample shows the most obvious hardening effect, with the largest decrease in scratch depth, demonstrating a good strengthening effect. In the HAZ region, the scratch depth of the aged sample decreases significantly, which is consistent with the fact that the HAZ showed the largest strengthening amplitude in the nanoindentation test mentioned earlier (H 3 / E 2 The significant increase in values ​​further validates that aging treatment significantly improves the wear resistance of this region through precipitation strengthening and microstructure densification. Furthermore, the reduced difference in scratch depth between HAZ and BM indicates improved mechanical property matching between the coating and the substrate, which helps reduce the risk of interfacial stress concentration and wear failure during service.

[0050] The three-dimensional morphology and cross-sectional profile of wear tracks on GH4169 substrate, clad state samples, and samples aged at 700℃ under the same load conditions were analyzed. The results are as follows: Figure 10 As shown. From Figure 10 As can be seen, the wear marks on the GH4169 substrate are the most obvious, with a wear rate reaching 1.95 × 10⁻⁶. -5 mm 3The wear track width and depth were approximately 511.4 μm and 5.41 μm (N·m), respectively, indicating severe plastic ploughing and surface damage. In contrast, the wear track depth and width of the clad sample decreased to 4.47 μm and 482.4 μm, respectively, suggesting that the cladding layer can improve the material's load-bearing capacity and wear resistance to some extent. However, after aging at 700℃, the sample exhibited the best wear resistance, with its wear rate decreasing to 1.56 × 10⁻⁶. -5 mm 3 The wear resistance (N·m) is reduced to 460.5 μm and the wear track width and depth are further reduced to 4.00 μm and 4.00 μm, respectively, and the wear track morphology is smoother. Therefore, the coating prepared by this invention and optimized by heat treatment can significantly improve the wear resistance of GH4169 surface, effectively reduce the plastic deformation and abrasive plowing effect on the material surface, and has excellent application prospects.

[0051] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. A method for preparing a laser cladding coating on a nickel-based alloy surface, characterized in that, Includes the following steps: (1) Ball mill the MoNiSi / La2O3 powder to obtain the pretreated powder; (2) The nickel-based alloy substrate is subjected to solution aging heat treatment and then cleaned and dried to obtain a pretreated substrate; (3) After mixing the binder with the pretreatment powder, the mixture is laid on the surface of the pretreatment substrate for laser cladding, and then subjected to aging heat treatment to obtain a laser cladding coating on the surface of the nickel-based alloy.

2. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, The mass ratio of Mo, Ni, Si and La2O3 in the MoNiSi / La2O3 powder is (41~42): (32~33): (23~24.5): (0.5~4).

3. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, The ball milling in step (1) includes the following steps: placing grinding steel balls and MoNiSi / La2O3 powder in a ball mill jar and loading it onto a planetary ball mill, introducing inert gas and then revolving around the planet while rotating on its own axis.

4. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 3, characterized in that, The mass ratio of the grinding steel ball to the MoNiSi / La2O3 powder is (8~12):1; the revolution speed is 80~120 rpm; the rotation speed is 180~220 rpm, with a pause of 5~10 min every 25~35 min; and the ball milling time is 4~6 h.

5. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, In step (2), the nickel-based alloy substrate is GH4169 nickel-based alloy substrate; the solution aging heat treatment includes the following steps: the nickel-based alloy substrate is solution treated at 950~970℃ for 0.5~1.5 h, air quenched, and then aged at 700~740℃ for 7.5~8.5 h, and after aging, it is cooled to 600~640℃ at a cooling rate of 45~55℃ / h and held for 7.5~8.5 h, and then air cooled to room temperature.

6. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, In step (3), the binder is polyvinyl alcohol; the volume ratio of the binder to the pretreated powder is (1~2):(1~2).

7. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, In step (3), the laser power of laser cladding is 1600~2000 W, the scanning speed is 10~20 mm / s, the laser spot diameter is 3~5 mm, and the overlap rate is 45~55%.

8. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 1, characterized in that, The aging heat treatment in step (3) includes the following steps: heating the pretreated substrate that has undergone surface laser cladding to 275-325°C at a heating rate of 4-6°C / min, then heating it to 675-725°C at a heating rate of 8-12°C / min, holding it at that temperature for 3.5-4.5 h, and then air cooling it to room temperature.

9. The method for preparing a laser cladding coating on a nickel-based alloy surface as described in claim 8, characterized in that, The aging heat treatment in step (3) includes the following steps: heating the pretreated substrate that has undergone surface laser cladding to 300°C at a heating rate of 5°C / min, then heating it to 700°C at a heating rate of 10°C / min, holding it at that temperature for 4 hours, and then air cooling it to room temperature.

10. A laser cladding coating on a nickel-based alloy surface prepared by the method described in any one of claims 1 to 9.

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