Laser cladding layer based on copper-magnesium-titanium-zirconium gradient design and preparation method thereof

Abstract

The invention relates to the technical field of metal surface engineering, and discloses a laser cladding layer based on copper-magnesium-titanium-zirconium gradient design and a preparation method thereof.The preparation method comprises gradient structure design, a microstructure strengthening mechanism, a laser cladding process and thermal field control. By constructing a copper-magnesium-titanium component gradient transition structure and matching the thermal expansion coefficient difference between a matrix and a coating in real time, interface thermal stress accumulation can be dynamically inhibited, the crack defect caused by thermal expansion mismatch of a traditional cladding layer is avoided, ordered diffusion of elements at the interface is promoted through gradual change of gradient components, and the thermal conductivity of the cladding layer is improved. The metallurgical bonding reliability of the coating and a base body is improved, meanwhile, a stable coating is formed, the long-term service stability under the extreme working condition is guaranteed, a microstructure strengthening mechanism regulation and control means is adopted, the coating has a stable and effective protective barrier in a corrosive medium environment, and the problem of performance degradation caused by structure defects of a traditional cladding layer is solved.

Description

Technical Field

[0001] This invention relates to the field of metal surface engineering technology, specifically to a laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design and its preparation method. Background Technology

[0002] Copper and copper alloys are valued for their excellent electrical and thermal conductivity. Copper alloys are alloys composed of pure copper as the base material and several other elements. Pure copper is purplish-red and is also known as red copper. Commonly used copper alloys are divided into three main categories: brass, bronze, and cupronickel. They are widely used in electromagnetic rails, continuous casting crystallizers, and marine equipment.

[0003] Current laser cladding technology for copper alloy surfaces has several drawbacks in practical applications: Due to copper's extremely high reflectivity to 1064nm lasers, traditional cladding processes require ultra-high power (greater than 5kW) to achieve cladding, leading to a sharp increase in the risk of thermal damage to the substrate. Furthermore, the mismatch in thermal expansion coefficients caused by high power increases the incidence of interfacial thermal stress cracks. At the same time, while existing single-component coating designs can improve surface hardness, they severely sacrifice conductivity, failing to meet the requirements of power equipment for synergistic strengthening of conductivity and wear resistance. In addition, the rapid solidification process forms coarse dendritic structures with large grain sizes, which not only exacerbates intergranular corrosion sensitivity but also causes a surge in the oxidation and weight gain rate of the cladding layer under high-temperature conditions, resulting in a decrease in conductivity and severely restricting its long-term service reliability in aerospace high-temperature components and marine corrosive environments.

[0004] Therefore, a laser cladding layer based on copper-magnesium-titanium-zirconium gradient design and its preparation method are proposed to solve the above problems. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design and its preparation method, thus solving the problems mentioned in the background art.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: a laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design and its preparation method, as detailed below:

[0009] S1. Gradient structure design: A transition layer and a reinforcement layer are sequentially constructed on the surface of the copper alloy substrate;

[0010] The transition layer consists of 5 sublayers with continuously varying compositions. The compositions of each layer, in the direction of increasing distance from the matrix, are as follows:

[0011] First layer: Cu: 85%, Mg: 8%, Ti: 6%, Y2O3: 1%;

[0012] Second layer: Cu: 82%, Mg: 9%, Ti: 8%, Y2O3: 1%;

[0013] Third layer: Cu: 79%, Mg: 10%, Ti: 10%, Y2O3: 1%;

[0014] Fourth layer: Cu: 76%, Mg: 11%, Ti: 12%, Y2O3: 1%;

[0015] Fifth layer: Cu: 73%, Mg: 12%, Ti: 14%, Y2O3: 1%;

[0016] The reinforcing layer consists of 5 zirconium-boron composite reinforcing sublayers. The composition of each layer, in the direction of increasing distance from the substrate, is as follows:

[0017] First layer: Cu: 70%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 1%, B4C: 2%;

[0018] Second layer: Cu: 67%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 2%, B4C: 4%;

[0019] Third layer: Cu: 64%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 3%, B4C: 6%;

[0020] Fourth layer: Cu: 61%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 4%, B4C: 8%;

[0021] Fifth layer: Cu: 58%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 5%, B4C: 10%;

[0022] S2. Microstructure enhancement mechanism: Adding Y2O3 nanoparticles with a particle size of 70nm;

[0023] S3. Laser cladding process: laser power 2.5kW, scanning speed 500mm / min, spot diameter 3mm, overlap rate 40%;

[0024] S4. Thermal field control: The temperature is controlled at 1300℃ through an infrared temperature measurement-PID closed-loop system, with temperature fluctuations less than 20℃.

[0025] Preferably, the gradient change of the Mg to Ti molar ratio in the transition layer satisfies the following equation:

[0026]

[0027] Where k mR is the rate of change of the Mg / Ti molar ratio gradient, R1 is the Mg / Ti molar ratio of the first layer, and R n d is the molar ratio of Mg to Ti in the nth layer, d is the thickness of a single layer, and n is the sequence number;

[0028] The gradient change is non-linear, with an inflection point at the third layer. The slope increment Δk at the inflection point is:

[0029] Δk=0.03-0.05 / mm

[0030] Where Δk is the slope increment at the inflection point.

[0031] Preferably, the in-situ reaction of the hard phase in the reinforcing layer conforms to the following formula:

[0032]

[0033] Where ΔT is the molten pool overheat temperature, and the other English characters are chemical elements.

[0034] Preferably, the copper alloy matrix is ​​chromium-zirconium copper, and the pretreatment includes:

[0035] Acetone ultrasonic cleaning for 10 minutes;

[0036] Laser texturing creates grooves with a depth of 25 μm.

[0037] After dehydration, isopropanol is kept at 60°C for 30 minutes in a vacuum drying oven.

[0038] Preferably, the laser cladding process applies ultrasonic vibration with a frequency of 40 kHz and an amplitude of 20 μm, with the vibration direction forming a 60° angle with the scanning direction.

[0039] Preferably, each layer of cladding powder is pretreated during the laser cladding process. The pretreatment process is as follows:

[0040] Ball milling: ball-to-material ratio 8:1, argon protection, speed 250 rpm, time 2 hours;

[0041] Powder drying treatment: vacuum environment, 110℃, for 1 hour, powder moisture content less than 0.02wt%;

[0042] Electrostatic dispersion: Applying a 10kV voltage eliminates agglomeration.

[0043] Preferably, a gradient cooling strategy is adopted for cooling the cladding layer during the laser cladding process, as follows:

[0044] The cooling rate of the transition layer is controlled at 100℃ / s;

[0045] The cooling rate of the reinforced layer has been increased to 200℃ / s;

[0046] This is achieved by adjusting the ratio of helium and argon mixed protective gas.

[0047] Preferably, the overlapping area of ​​the laser cladding layer is treated with laser remelting, and the remelting parameters are as follows:

[0048] The power density is 40% of that of the main cladding, the scanning speed is increased by 3 times, and the number of remelting times is 2.

[0049] Preferably, a 1 μm thick transition zone is formed at the interface of the cladding layer, and this region has a Mg2CuTi+TiCu2 dual-phase structure with a grain size of 0.5 μm.

[0050] Preferably, a method for preparing a laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design, wherein the prepared laser cladding layer based on the copper-magnesium-titanium-zirconium gradient design ultimately achieves the following performance indicators:

[0051] The bonding strength with the matrix is ​​greater than 450 MPa;

[0052] Surface hardness HV 0·2 320-400;

[0053] The oxidation resistance at 700℃ is 10 times higher than that of the matrix;

[0054] The critical load for anti-fusion welding is greater than 180N.

[0055] (III) Beneficial Effects

[0056] Compared with the prior art, the present invention provides a laser cladding layer based on copper-magnesium-titanium-zirconium gradient design and its preparation method, which has the following beneficial effects:

[0057] 1. In this invention, by setting a gradient transition end, when preparing a copper alloy surface cladding layer, a copper-magnesium-titanium composition gradient transition structure is constructed to match the difference in thermal expansion coefficients between the substrate and the coating in real time. This can dynamically suppress the accumulation of interfacial thermal stress, avoid crack defects caused by thermal expansion mismatch in traditional cladding layers, and optimize element interdiffusion behavior by utilizing the gradual change of gradient composition, thereby improving the metallurgical bonding reliability between the coating and the substrate and ensuring long-term service stability under extreme conditions.

[0058] 2. In this invention, by setting a microstructure strengthening mechanism, rare earth oxide nanoparticles are introduced during the laser cladding process to control the grain growth behavior during the solidification process of the molten pool in real time, automatically correct the abnormal coarsening trend of dendrites, so that the cladding layer structure is uniform and refined, and the formation of pores and grain boundary corrosion sensitivity are suppressed at the same time, ensuring that the coating maintains a dense protective barrier in the corrosive medium environment, and solving the performance degradation problem caused by the structural defects of traditional cladding layers.

[0059] 3. In this invention, by setting up a functional synergy end, a hard phase composite structure is generated in situ in the design of the reinforcement layer. Based on the requirements of wear resistance, conductivity and corrosion resistance, multiple performance synergy optimization is automatically achieved, breaking through the functional imbalance limitation of single-component coatings. This allows the coating to maintain high conductivity when subjected to high-pressure friction and form a self-stabilizing protective film in a high-temperature oxidation environment. It fully covers the core performance requirements of power equipment and marine equipment in multiple scenarios, and improves the multi-functional integrated reinforcement effect. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0061] Figure 2 This is a schematic diagram of the transition alloy layer structure of the present invention;

[0062] Figure 3 This is a schematic diagram of the in-situ reinforcement layer structure of the present invention;

[0063] Figure 4 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] Please see Figures 1-4 A laser cladding layer based on copper-magnesium-titanium-zirconium gradient design and its preparation method, S1, gradient structure design: a transition layer and a strengthening layer are sequentially constructed on the surface of a copper alloy substrate;

[0066] The transition layer consists of 5 sublayers with continuously varying compositions. The compositions of each layer, in the direction of increasing distance from the matrix, are as follows:

[0067] First layer: Cu: 85%, Mg: 8%, Ti: 6%, Y2O3: 1%;

[0068] Second layer: Cu: 82%, Mg: 9%, Ti: 8%, Y2O3: 1%;

[0069] Third layer: Cu: 79%, Mg: 10%, Ti: 10%, Y2O3: 1%;

[0070] Fourth layer: Cu: 76%, Mg: 11%, Ti: 12%, Y2O3: 1%;

[0071] Fifth layer: Cu: 73%, Mg: 12%, Ti: 14%, Y2O3: 1%;

[0072] The reinforcing layer consists of 5 zirconium-boron composite reinforcing layers. The composition of each layer, in the direction of increasing distance from the substrate, is as follows:

[0073] First layer: Cu: 70%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 1%, B4C: 2%;

[0074] Second layer: Cu: 67%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 2%, B4C: 4%;

[0075] Third layer: Cu: 64%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 3%, B4C: 6%;

[0076] Fourth layer: Cu: 61%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 4%, B4C: 8%;

[0077] Fifth layer: Cu: 58%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 5%, B4C: 10%;

[0078] S2. Microstructure enhancement mechanism: Adding Y2O3 particles with a particle size of 70nm;

[0079] S3. Laser cladding process: laser power 2.5kW, scanning speed 500mm / min, spot diameter 3mm, overlap rate 40%;

[0080] S4. Thermal field control: The temperature is controlled at 1300℃ through an infrared temperature measurement-PID closed-loop system, with temperature fluctuations less than 20℃.

[0081] The gradient change of the Mg and Ti molar ratio in the transition layer satisfies the following equation:

[0082]

[0083] Where k m R is the rate of change of the Mg and Ti molar ratio gradient, R1 is the Mg and Ti molar ratio of the first layer, and R n d is the molar ratio of Mg to Ti in the nth layer, d is the thickness of a single layer, and n is the sequence number;

[0084] The gradient change is non-linear, with an inflection point at the third layer. The slope increment Δk at the inflection point is:

[0085] Δk=0.03-0.05 / mm

[0086] Where Δk is the slope increment at the inflection point.

[0087] The in-situ reaction of the hard phase in the reinforcement layer conforms to the following formula:

[0088]

[0089] Where ΔT is the molten pool overheat temperature, and the other English characters are chemical elements.

[0090] The copper alloy matrix is ​​chromium-zirconium copper, and the pretreatment includes:

[0091] Acetone ultrasonic cleaning for 10 minutes;

[0092] Laser texturing creates grooves with a depth of 25 μm.

[0093] After dehydration, isopropanol is kept at 60°C for 30 minutes in a vacuum drying oven.

[0094] The laser cladding process applies ultrasonic vibration with a frequency of 40kHz and an amplitude of 20μm, with the vibration direction at a 60° angle to the scanning direction.

[0095] During the laser cladding process, each layer of cladding powder undergoes pretreatment, as follows:

[0096] Ball milling: ball-to-material ratio 8:1, argon protection, speed 250 rpm, time 2 hours;

[0097] Powder drying treatment: vacuum environment, 110℃, for 1 hour, powder moisture content less than 0.02wt%;

[0098] Electrostatic dispersion: Applying a 10kV voltage eliminates agglomeration.

[0099] During the laser cladding process, a gradient cooling strategy is used to cool the cladding layer, as detailed below:

[0100] The cooling rate of the transition layer is controlled at 100℃ / s;

[0101] The cooling rate of the reinforced layer has been increased to 200℃ / s;

[0102] This is achieved by adjusting the ratio of helium and argon mixed protective gas.

[0103] The overlapping areas of the laser cladding layer are treated with laser remelting, and the remelting parameters are as follows:

[0104] The power density is 40% of that of the main cladding, the scanning speed is increased by 3 times, and the number of remelting times is 2.

[0105] A 1 μm thick transition zone is formed at the interface of the cladding layer. This region contains a Mg2CuTi+TiCu2 dual-phase structure with a grain size of 0.5 μm.

[0106] The laser cladding layer based on the copper-magnesium-titanium-zirconium gradient design ultimately achieves the following performance indicators:

[0107] The bonding strength with the matrix is ​​greater than 450 MPa;

[0108] Surface hardness HV 0.2 320-400;

[0109] The oxidation resistance at 700℃ is 10 times higher than that of the matrix;

[0110] The critical load for anti-fusion welding is greater than 180N.

[0111] Example 1: Enhanced Manufacturing of Key Components for Ultra-High Voltage Power Grid Switches

[0112] To address the reinforcement requirements of precision components in vacuum arc-extinguishing devices in 550kV UHV transmission systems, high-performance copper-chromium alloy was selected as the base material for cladding processing. First, the working surface of the component underwent laser pretreatment. Under high-purity inert gas protection, a specific frequency pulsed laser beam was used for scanning to form a three-dimensional mesh structure. The transition layer used a special alloy powder with a high copper ratio, and the laser energy was set within the lower limit of the standard value. The proportion of strengthening elements was gradually increased and the copper content was adjusted. When transitioning from the transition layer to the strengthening layer, a special alloy powder with a high proportion of strengthening elements was used. Throughout the process, a temperature closed-loop control module was used to maintain a stable molten pool temperature.

[0113] The preparation process of the reinforcement layer introduces key metal element synthesis technology. The first layer of the reinforcement layer uses standard reinforced alloy powder, which is activated to generate specific intermetallic compounds in an ultra-high temperature environment. In subsequent processing stages, the content of key reinforcement elements is gradually increased, reaching a set peak concentration in the highest stage. High-frequency mechanical vibration is applied simultaneously during processing to optimize the crystal structure. After cladding, the component undergoes rapid cooling and finally fine surface finishing. After passing the maximum current impact test, the conductivity of this reinforced component remains optimal, with no abnormal adhesion on the surface. The overall life cycle exceeds that of components using conventional reinforcement technology by more than seven times, completely solving the problem of material stability under ultra-high voltage environments.

[0114] Example 2: Protection and Reinforcement Engineering of Deep-Sea Equipment Transmission System

[0115] This technology is applied to the corrosion protection of core transmission components in the propulsion mechanism of marine resource exploration platforms. It utilizes a special stainless steel substrate with composite cladding strengthening. The substrate pretreatment employs a two-stage technique: first, an ultra-thin transition medium layer is formed through chemical deposition, followed by precision laser micro-pore processing to create a three-dimensional array structure. The transition layer manufacturing adopts a modified alloy system design: the substrate is adjusted to a copper-nickel hybrid alloy system, utilizing the bimetallic synergistic effect to optimize the interface state.

[0116] The reinforcement layer implementation phase innovatively adopts a dual-energy synergistic system: during the surface cladding process of the main energy equipment, the auxiliary energy performs thermal stabilization treatment on the cladding interface area; during the cladding process of the reinforcement layer, composite alloy powder containing special additives is added to form a reinforcing phase at the grain boundary that can enhance corrosion resistance; in the final stage, acid pickling and passivation and organic sealing processes are implemented to build a multi-protection system. After accelerated corrosion verification by professional institutions, the cladding reinforcement component showed reduced material loss and reduced surface damage density after continuous operation for a standard period of time in a typical marine corrosion environment, successfully resisting the dual erosion effects of deep-sea high pressure environment and biological corrosion.

[0117] Example 3: Strengthening of High-Temperature Sealing Interfaces in Aerospace Propulsion Systems

[0118] To address the high-temperature failure of sealing components in turbine mechanisms of novel aerospace propulsion systems, gradient cladding reinforcement is implemented at the copper alloy sealing interface, and a groundbreaking intelligent cooling device is adopted: during the cladding transition layer stage, a low-temperature medium is introduced to maintain the stability of the substrate temperature, and during the reinforcement layer stage, ultra-low temperature spraying is switched to achieve instantaneous solidification.

[0119] The transition layer composition design focuses on thermal expansion matching: the first layer maintains a low expansion characteristic metal ratio; the second, third and fourth layers add trace amounts of fibrous reinforcing materials to control dimensional deformation; the fifth layer forms a basic alloy system with thermal insulation function; the reinforcement layer is manufactured using a unique reaction control technology: high-performance alloy powder is premixed according to a specific formula, and after the key compound transformation is completed in the extreme temperature molten pool, a special gas mixture is immediately injected to guide the formation of a continuous and dense protective layer structure.

[0120] After precision machining, the sealing working surface is subjected to ion penetration strengthening treatment to form a double-layer reinforced structure. The sealing component performed excellently in thermal cycling tests under simulated launch environment. After thousands of temperature shocks, the sealing capacity remained at the best level, and the friction coefficient remained stable in the excellent range, solving the risk of interface failure during multiple rocket ignitions.

[0121] Example 4: Strengthening of Wear-Resistant Components in Precision Hydraulic Systems

[0122] To address the wear and failure issues of key hydraulic transmission components in high-end engineering machinery, a composite cladding strengthening method is implemented on a special alloy steel substrate. An innovative approach is adopted, using a rotating tooling system in conjunction with a laser synchronous tracking system: the substrate is fixed on a high-speed rotating platform, and the laser head moves precisely radially to perform spiral cladding.

[0123] The transition layer is designed as a three-layer transition system: the first layer uses a nickel-based bonding alloy to ensure interface bonding; the second layer forms a copper-iron gradient transition layer; the third layer is adjusted to a copper-based composite alloy with anti-friction properties; the strengthening layer is implemented in stages: the first half is cladding with composite powder containing a solid lubricating phase; the second half gradually increases the concentration of hard reinforcing elements; the laser power is dynamically adjusted by monitoring the reflectivity of the molten pool in real time; in the final stage, the working surface is treated with laser micro-texturing to construct a surface micro-oil storage structure; and the post-treatment uses vacuum sulfurizing technology to enhance self-lubrication.

[0124] After tens of thousands of durability tests, the friction coefficient of the reinforced components remained stable within the optimal range, key wear indicators decreased, and stable pressure output performance was maintained under continuous heavy load conditions, significantly extending the overhaul cycle of the hydraulic system.

[0125] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0126] 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 laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design, characterized in that, Specifically as follows: S1. Gradient structure design: A transition layer and a reinforcement layer are sequentially constructed on the surface of the copper alloy substrate; The transition layer consists of 5 sublayers with continuously varying compositions. The compositions of each layer, in the direction of increasing distance from the matrix, are as follows: First layer: Cu: 85%, Mg: 8%, Ti: 6%, Y2O3: 1%; Second layer: Cu: 82%, Mg: 9%, Ti: 8%, Y2O3: 1%; Third layer: Cu: 79%, Mg: 10%, Ti: 10%, Y2O3: 1%; Fourth layer: Cu: 76%, Mg: 11%, Ti: 12%, Y2O3: 1%; Fifth layer: Cu: 73%, Mg: 12%, Ti: 14%, Y2O3: 1%; The reinforcing layer consists of 5 zirconium-boron composite reinforcing sublayers. The composition of each layer, in the direction of increasing distance from the substrate, is as follows: First layer: Cu: 70%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 1%, B4C: 2%; Second layer: Cu: 67%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 2%, B4C: 4%; Third layer: Cu: 64%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 3%, B4C: 6%; Fourth layer: Cu: 61%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 4%, B4C: 8%; Fifth layer: Cu: 58%, Mg: 12%, Ti: 14%, Y2O3: 1%, Zr: 5%, B4C: 10%; S2. Microstructure enhancement mechanism: Adding Y2O3 nanoparticles with a particle size of 70nm; S3. Laser cladding process: laser power 2.5kW, scanning speed 500mm / min, spot diameter 3mm, overlap rate 40%; S4. Thermal field control: The temperature is controlled at 1300℃ through an infrared temperature measurement-PID closed-loop system, with temperature fluctuations less than 20℃.

2. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: The gradient change of the Mg and Ti molar ratio in the transition layer satisfies the following equation: Where k m R is the rate of change of the Mg and Ti molar ratio gradient, R1 is the Mg and Ti molar ratio of the first layer, and R n d is the molar ratio of Mg to Ti in the nth layer, d is the thickness of a single layer, and n is the sequence number; The gradient change is non-linear, with an inflection point at the third layer. The slope increment Δk at the inflection point is: Δk=0.03-0.05 / mm Where Δk is the slope increment at the inflection point.

3. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: The in-situ reaction of the hard phase in the reinforcement layer conforms to the following formula: Where ΔT is the overheating temperature of the molten pool, and the other English characters are chemical elements.

4. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: The copper alloy matrix is ​​chromium-zirconium copper, and the pretreatment includes: Acetone ultrasonic cleaning for 10 minutes; Laser texturing creates grooves with a depth of 25 μm. After dehydration, isopropanol is kept at 60°C for 30 minutes in a vacuum drying oven.

5. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: The laser cladding process applies ultrasonic vibration with a frequency of 40kHz and an amplitude of 20μm, with the vibration direction at a 60° angle to the scanning direction.

6. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: During the laser cladding process, each layer of cladding powder undergoes pretreatment, as follows: Ball milling: ball-to-material ratio 8:1, argon protection, speed 250 rpm, time 2 hours; Powder drying treatment: vacuum environment, 110℃, for 1 hour, powder moisture content less than 0.02wt%; Electrostatic dispersion: Applying a 10kV voltage eliminates agglomeration.

7. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: During the laser cladding process, a gradient cooling strategy is used to cool the cladding layer, as detailed below: The cooling rate of the transition layer is controlled at 100℃ / s; The cooling rate of the reinforced layer has been increased to 200℃ / s; This is achieved by adjusting the ratio of helium and argon mixed protective gas.

8. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: The overlapping areas of the laser cladding layer are treated with laser remelting, and the remelting parameters are as follows: The power density is 40% of that of the main cladding, the scanning speed is increased by 3 times, and the number of remelting times is 2.

9. The laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design according to claim 1, characterized in that: A 1 μm thick transition zone is formed at the interface of the cladding layer. This region contains a Mg2CuTi+TiCu2 dual-phase structure with a grain size of 0.5 μm.

10. A method for preparing a laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design, wherein the laser cladding layer based on a copper-magnesium-titanium-zirconium gradient design is prepared according to any one of claims 1-9, characterized in that: The laser cladding layer prepared based on the copper-magnesium-titanium-zirconium gradient design ultimately achieved the following performance indicators: The bonding strength with the matrix is ​​greater than 450 MPa; Surface hardness HV 0·2 320-400; The oxidation resistance at 700℃ is 10 times higher than that of the matrix; The critical load for anti-fusion welding is greater than 180N.

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