A copper alloy liquid cooling radiator and a preparation method thereof

Abstract

The application belongs to the alloy field, and specifically discloses a copper alloy liquid cooling radiator and a preparation method thereof.In the method, the copper alloy powder is used to print the alloy layer of the liquid flow radiator layer by layer on a substrate; after each layer is printed, the layer is subjected to remelting treatment, so that the defects in the alloy are reduced, and the growth quality of the alloy layer is improved; then, the printed alloy part after printing is subjected to blowing treatment, so that the residual powder or impurities in the liquid flow channel can be effectively removed, the probability of liquid flow channel blockage is reduced, and the heat dissipation performance of the device is improved; finally, the printed alloy part is subjected to heat treatment, so that the stress in the alloy is released, and the size stability and mechanical properties of the liquid cooling radiator are improved.Through the preparation method, the liquid cooling radiator has high compactness, high precision, high heat dissipation performance and low residual stress, and can meet the heat dissipation requirements in actual engineering applications.

Description

Technical Field

[0001] This invention belongs to the field of alloys, and specifically relates to a copper alloy liquid-cooled heat sink and its preparation method. Background Technology

[0002] Copper and copper alloys, due to their excellent thermal and electrical conductivity and good corrosion resistance, hold an irreplaceable position in heat dissipation devices in electronic equipment, new energy vehicles, aerospace, and other fields. As a high-efficiency heat dissipation component, the unobstructed flow of internal channels, structural density, dimensional accuracy, and residual stress level of copper alloy microchannel liquid coolers directly determine their heat dissipation efficiency, assembly reliability, and long-term stability. Traditional manufacturing processes (such as casting and machining) suffer from long manufacturing cycles, low material utilization, and difficulties in forming complex flow channels when preparing copper alloy microchannel liquid coolers with complex internal channels, making it difficult to meet the high-performance requirements of modern industry for precision heat dissipation devices. Laser additive manufacturing (also known as 3D printing), based on the discrete-stacking principle, can achieve near-net-shape forming of complex structural parts, providing a new technological path for the manufacturing of copper alloy microchannel liquid coolers.

[0003] However, copper alloys have low absorption rates for near-infrared lasers and high thermal conductivity, making them prone to molten pool instability during laser additive manufacturing. This can easily lead to defects such as porosity, cracks, deformation, unfused particles, and excessive residual stress. More importantly, the internal microchannel structure of copper alloy liquid-cooled heat sinks is susceptible to leaving unmelted or semi-melted copper alloy powder during the printing process. This residual powder can clog the flow channels, reduce heat dissipation efficiency, and even cause heat sink failure. Specifically, this is because: rapid heat conduction in copper alloys leads to rapid cooling of the molten pool, making it difficult for gases to escape and forming pores; the thermal stress and solidification shrinkage stress generated by rapid heating and cooling can easily cause cracks in the copper alloy, and the presence of residual stress can affect the dimensional stability of the workpiece during subsequent use; the thin-walled structure of the complex microchannels in copper alloy liquid-cooled heat sinks has low stiffness and is sensitive to thermal stress, making it prone to deformation; simultaneously, the narrow internal space of the microchannels in copper alloy liquid-cooled heat sinks makes it difficult for un-formed powder to fall off naturally during printing, resulting in residual accumulation. Therefore, developing an additive manufacturing process that can effectively control defects, reduce residual stress, thoroughly clean residual powder inside microchannels, and achieve high-quality forming of copper alloy microchannel liquid cooling plates has significant engineering application value. Summary of the Invention

[0004] To address the problems of numerous defects, blocked flow channels, and poor heat dissipation performance in copper alloy liquid coolers manufactured using additive manufacturing (3D printing) as described above, this invention provides a copper alloy liquid cooler and its manufacturing method. The method of this invention achieves high-density, high-precision, low-residual-stress, and unobstructed internal flow channels in the copper alloy microchannel liquid cooler through the synergistic effect of an in-situ remelting strategy, a microchannel internal powder cleaning process, and a heat treatment process. This solves the defects and internal residual powder problems inherent in traditional processes and conventional additive manufacturing processes.

[0005] To achieve the above objectives, the following technical solutions are specifically included: On one hand, the present invention provides a method for preparing a copper alloy liquid-cooled heat sink, comprising the following steps: S1. Copper alloy powder and substrate are placed in a laser additive manufacturing equipment. According to the liquid cooling heat sink model with liquid flow channels and its slicing path, alloy layers are printed layer by layer on the substrate. Each alloy layer is printed by sequentially including copper alloy powder laying, laser printing and remelting. After printing, the substrate is cooled and removed to obtain the printed alloy part. The printed alloy part has liquid flow channels. S2. Compressed air is used to purge the liquid flow channels in the printed alloy part, and then the part is cleaned and dried to obtain the cleaned printed alloy part. S3. The cleaned printed alloy part is heat-treated in an inert gas atmosphere to obtain a copper alloy liquid-cooled heat sink.

[0006] In the preparation method of this invention, the alloy layers of a copper alloy liquid-cooled heat sink are printed layer by layer in a laser additive manufacturing equipment. Simultaneously, after each alloy layer is printed, it undergoes in-situ remelting. This in-situ remelting is performed before the cladding layer has completely cooled, which fully utilizes residual heat, reduces energy consumption, effectively eliminates defects such as pores and microcracks generated during each printing layer, significantly reduces residual stress in the workpiece, and thoroughly removes residual powder inside the microchannels. This avoids problems such as alloy molten pool splashing and coarse grains caused by high-power laser input during printing, improves the interlayer metallurgical bonding quality, reduces internal defects in the liquid-cooled heat sink, and results in a liquid-cooled heat sink with high density, good structural integrity and sealing, excellent dimensional stability, and unobstructed internal liquid flow channels, thus exhibiting high heat dissipation performance.

[0007] Preferably, in step S1, the copper alloy powder comprises the following components by mass percentage: Cr 0.5%-1.5%, Zr 0.05%-0.3%, with the balance being Cu and unavoidable impurities. The Cr element in the alloy powder can form solid solution strengthening and a fine-grained structure, improving the high-temperature strength and density of the material; the Zr element can combine with oxygen to form stable oxides, reducing oxide inclusions, while also refining the grains and improving the forming quality.

[0008] Preferably, in step S1, the loose packing density of the copper alloy powder is 4.0-4.5 g / cm³. 3 The copper alloy powder exhibits a flowability of 15-25 s / 50g, a D10 of 20-25 μm, a D50 of 30-45 μm, a D90 of 50-55 μm, and an oxygen content of ≤500 ppm. Suitable bulk density and flowability ensure uniform powder distribution; lower oxygen content reduces porosity and oxide inclusions during printing. Using copper alloy powder with these performance parameters results in excellent powder distribution uniformity and flowability during printing. Combined with in-situ remelting, heat treatment, and internal cleaning of the liquid flow channels, high-quality molding of complex microchannel liquid-cooled heat sinks can be achieved without additional support structures, improving material utilization, shortening the manufacturing cycle, and reducing production costs.

[0009] Preferably, in step S1, the copper alloy powder further undergoes vacuum drying and sieving. The vacuum drying temperature is 80-120℃, the vacuum drying time is 2-6 hours, the vacuum degree is 0.1-0.001 Pa, and the mesh size of the sieve used for sieving is 50-150 μm. Vacuum drying removes adsorbed moisture and gas from the alloy powder. After the vacuum-dried copper alloy powder cools naturally to room temperature, it is sieved to disperse any agglomerated copper alloy powder, ensuring good flowability and laying the foundation for uniform powder spreading in subsequent steps.

[0010] Preferably, in step S1, the substrate further undergoes polishing, cleaning, and vacuum drying. Polishing, cleaning, and drying remove oxide films and impurities from the substrate, ensuring a clean and smooth substrate surface.

[0011] Preferably, the substrate is made of stainless steel.

[0012] Placing copper alloy powder and a substrate in a laser additive manufacturing equipment includes the following steps: fixing the substrate on the printing platform of the laser additive manufacturing equipment, leveling the printing chamber, and then introducing argon gas for gas purging to remove air from the chamber; placing the copper alloy powder in the powder storage bin of the laser additive manufacturing equipment.

[0013] Preferably, in step S1, the liquid flow channels in the printed alloy part include a triple periodic minimal surface (TPMS) fin structure with a fin thickness of 2-5 mm. A liquid-cooled radiator model containing the liquid flow channels is constructed using 3D modeling software. The internal liquid flow channels of the liquid-cooled radiator adopt a triple periodic minimal surface (TPMS) fin structure to increase the heat exchange area. The liquid-cooled radiator model containing the liquid flow channels is imported into slicing software for slicing processing to generate a corresponding slicing path file. This process establishes the process parameters for the printing process. The corresponding parameters in the slicing path file are set in advance in the additive manufacturing equipment to ensure the accuracy of the printing process.

[0014] Preferably, in step S1, the laser printing includes the following process parameters: the printed layer thickness is 0.02-0.03 mm, the laser wavelength is 1000-1100 nm, the laser power is 200-400 W, the scanning speed is 500-800 mm / s, the scanning spacing is 0.07-0.1 mm, and the scanning method is "Z" shaped scanning or "chessboard" scanning.

[0015] Preferably, in step S1, the angle between layers during the layer-by-layer printing of the alloy layer is 40°-70°.

[0016] Preferably, in step S1, the atmosphere during laser printing and remelting is an inert gas atmosphere, wherein the inert gas includes at least one of argon, nitrogen, and helium. The inert gas atmosphere is maintained by continuously introducing inert gas into the printing chamber at a flow rate controlled at 20-30 L / min to prevent oxidation of the copper alloy powder and the formed printed parts at high temperatures.

[0017] Preferably, in step S1, the remelting process includes the following process parameters: laser wavelength of 1000-1100nm, laser power of 200-400W, scanning speed of 500-800mm / s, scanning spacing of 0.07-0.1mm, and scanning method of "Z" shaped scanning or "checkerboard" scanning. The laser wavelength of 1000-1100nm is a laser source in the near-infrared band. Using the above-mentioned laser power, scanning speed, scanning spacing, layer thickness, and interlayer rotation angle is more conducive to the high-quality and more complete formation of the liquid flow channel structure, and is beneficial to obtaining a liquid-cooled heat sink with high density, low thermal resistance, and low pressure drop. In-situ remelting can reheat the newly formed cladding layer, promote the escape of gas in the molten pool, eliminate porosity defects, refine grains, relieve thermal stress, inhibit crack generation, and improve interlayer bonding strength and density.

[0018] More preferably, in step S1, the laser wavelength, laser power, scanning rate, scanning spacing, and scanning mode are the same in the laser printing and remelting processes.

[0019] Preferably, in step S1, the method of removing the substrate includes wire cutting.

[0020] Preferably, in step S2, the purging pressure is 0.1-1 MPa, the purging time is 5-180 min, and the purging method is as follows: first, compressed air is used to purge the surface of the printed alloy part; then, compressed air is introduced into the liquid flow channel from the inlet or outlet of the liquid flow channel on the printed alloy part through a nozzle for purging, and the purging is performed alternately from both the inlet and outlet of the liquid flow channel. The combination of compressed air purging and ultrasonic cleaning is used to remove residual powder inside the microchannel, and the air is purged alternately along the inlet and outlet of the microchannel to blow out most of the loose residual powder inside the channel.

[0021] Preferably, in step S2, the cleaning solvent includes ethanol, the cleaning is performed under ultrasound with a power of 200-800W, and the cleaning time is 60-240 minutes. The drying is vacuum drying at a temperature of 80-150℃ for 1-6 hours. The cavitation effect of ultrasound is used to remove stubborn residual powder and impurities adhering to the inner wall of the microchannel, ensuring the unobstructed flow within the microchannel.

[0022] In the composite cleaning process that combines compressed air purging and ultrasonic cleaning, compressed air purging can quickly remove loose powder in the liquid flow channel, while ultrasonic cleaning utilizes the cavitation effect of the medium to efficiently peel off stubborn powder adhering to the inner wall. The synergistic effect of the two ensures that there are no residues inside the microchannel, guarantees smooth flow, and avoids affecting heat dissipation efficiency due to powder blockage. The vacuum drying process can thoroughly remove solvent residues after cleaning, preventing the workpiece from getting damp or oxidizing.

[0023] Preferably, in step S3, the heat treatment temperature is 400-550℃, the heat treatment time is 1-6 hours, the heating rate to the heat treatment temperature is 5-12℃ / min, and the heat treatment is completed by natural cooling to room temperature. Heating at the above-mentioned heating rate avoids excessively rapid heating that could generate new thermal stress. The heat treatment holding stage promotes the release of residual stress and the homogenization of the microstructure. The inert gas atmosphere effectively prevents workpiece oxidation, and natural cooling with the furnace further reduces stress generated during cooling, significantly improving the dimensional stability and mechanical properties of the workpiece. This heat treatment process further releases residual stress generated during printing, optimizes the workpiece's microstructure, improves the material's mechanical properties and dimensional stability, avoids deformation or cracking due to stress release during subsequent use, and ensures the reliability of the liquid-cooled radiator under long-term high-temperature heat dissipation conditions.

[0024] On the other hand, the present invention provides a copper alloy liquid-cooled heat sink, which is prepared by the method for preparing the copper alloy liquid-cooled heat sink.

[0025] Preferably, the density of the copper alloy liquid-cooled heat sink is 98.0%-99.9%.

[0026] Preferably, at a liquid flow rate of 3.8 L / min and a liquid temperature of 20 °C, the thermal resistance of the liquid-cooled radiator is 0.006-009 °C / W, and the pressure drop is 262-279 kPa.

[0027] Compared with existing technologies, this invention has the following advantages: In the method of this invention, copper alloy powder is first printed layer by layer onto a substrate to form alloy layers for the liquid cooling heat sink. After each layer is printed, it is remelted to reduce defects in the alloy and improve the growth quality of the alloy layer. Then, the printed alloy parts are purged to effectively remove residual powder or impurities from the liquid flow channels, reducing the probability of blockage and improving the heat dissipation performance of the device. Finally, the printed alloy parts are heat-treated to release stress in the alloy, improving the dimensional stability and mechanical properties of the liquid cooling heat sink. The preparation method of this invention enables the liquid cooling heat sink to have high density, high precision, high heat dissipation performance, and low residual stress, meeting the heat dissipation requirements of practical engineering applications. Furthermore, the preparation method of this invention features smooth transitions between processes, simple operation, high stability, and a highly targeted and effective internal powder cleaning process, facilitating industrial-scale application and significantly expanding the application scope of copper alloys in precision heat dissipation devices. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the external three-dimensional structure of the 3D-printed copper alloy liquid-cooled heat sink according to Embodiment 1 of the present invention.

[0029] Figure 2 This is a physical image of the 3D-printed copper alloy liquid-cooled heat sink according to Embodiment 1 of the present invention.

[0030] Figure 3 This is a schematic diagram of the internal structure of the 3D-printed copper alloy liquid-cooled heat sink according to Embodiment 1 of the present invention.

[0031] Figure 4 This is a field photo of the heat dissipation performance test of the 3D printed copper alloy liquid cooler in Embodiment 1 of the present invention. Detailed Implementation

[0032] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0033] Example 1 A method for near-infrared laser additive manufacturing of a copper alloy liquid-cooled heat sink includes the following steps: (1) Copper alloy powder pretreatment: Copper alloy powder containing 0.85wt%Cr and 0.13wt%Zr was selected. Its performance parameters were: D10=21.05μm, D50=38.61μm, D90=54.86μm, oxygen content 183.45ppm, and loose packing density 4.27g / cm³. 3 The flowability was 17.8 s / 50 g. The alloy powder was placed in a vacuum dryer and dried at 120°C for 4 hours. After natural cooling, it was sieved using a 100 μm sieve to obtain pretreated copper alloy powder. The pretreated copper alloy powder was then placed in the powder storage hopper of a laser additive manufacturing equipment.

[0034] (2) Model design and slicing: A three-dimensional model of a copper alloy liquid cooler containing microchannels was constructed using three-dimensional software. The model included the microchannels inside the liquid cooler, which were designed as triple periodic minimal surface (TPMS) fins with a fin thickness of 2 mm. The model was then imported into slicing software to generate a slicing path file to determine the process parameters for printing each subsequent alloy layer.

[0035] (3) Preparation before additive printing: Select a 316L stainless steel substrate, grind it to remove the oxide film, clean and dry it with ethanol, and fix it on the printing platform of the near-infrared laser additive manufacturing equipment; after leveling the printing chamber, purge it with argon gas for 30 minutes.

[0036] (4) Additive printing and in-situ remelting: Argon protective gas is continuously introduced, and the argon flow rate is controlled at 25L / min; according to the slicing path file, the near-infrared laser additive manufacturing equipment is started, and the laser wavelength is 1064nm; the copper alloy powder in the powder storage hopper is quantitatively discharged through the powder feeder, and the powder is evenly spread on the surface of the stainless steel substrate on the printing platform using a powder spreading scraper to form an alloy powder layer of a set thickness; after each layer of powder is spread, laser printing and in-situ remelting are performed to obtain the alloy layer; after the remelting process is completed, the next alloy layer of powder spreading, laser printing and remelting process are performed again. The process of layer-by-layer powder spreading, laser printing and remelting is repeated according to the slicing path file until the entire product is printed and the printed alloy part is formed on the substrate.

[0037] The process parameters for each laser printing were: laser power 280W, scanning speed 500mm / s, layer thickness 0.03mm, scanning spacing 0.09mm, "Z" shaped scanning, and interlayer rotation angle of 67° between alloy layers. After each alloy layer was laser printed, in-situ remelting was immediately performed using the same laser scanning parameters: laser power 280W, scanning speed 500mm / s, scanning spacing 0.09mm, and "Z" shaped scanning. After the printing chamber cooled naturally to room temperature, the printed alloy part and substrate assembly were removed and separated by wire cutting. According to the designed model and slicing files, the printed alloy part contained microchannels with a triple-periodic minimal surface texture (TPMS) fin structure.

[0038] (5) Surface blowing and cleaning: Use compressed air of 0.5MPa to blow away the loose powder on the surface to complete the surface powder cleaning; (6) Internal purging and cleaning: Compressed air is introduced into the microchannel from the inlet or outlet of the printed alloy part through the nozzle to purge the inside of the microchannel. Compressed air of 0.5MPa is used to purge alternately along the inlet and outlet of the microchannel for a total of 60 minutes to complete the internal powder cleaning. Then, the workpiece is placed in an ultrasonic cleaning tank containing ethanol, the cleaning power is set to 700W, and the cleaning is carried out for 80 minutes. After cleaning, the workpiece is placed in a vacuum drying oven at 120℃ to dry for 2 hours.

[0039] (7) Heat treatment: The cleaned printed alloy parts are placed in a tube furnace, and flowing argon gas is introduced as a protective gas. The temperature is raised to 480°C at a rate of 10°C / min and held for 2 hours. Then, the parts are cooled to room temperature in the furnace under the atmosphere of flowing argon gas to obtain the finished copper alloy liquid-cooled heat sink.

[0040] Example 2 The difference between this embodiment and embodiment 1 is that the printing process parameters in step (4) are different, as follows: The printing process parameters in this embodiment are as follows: laser power 320W, scanning speed 600mm / s, layer thickness 0.03mm, scanning spacing 0.09mm, "Z" shaped scanning, and interlayer rotation angle 67°. After each alloy layer is laser printed, it is immediately remelted in situ using the same laser scanning parameters. The rest of the process is the same.

[0041] Example 3 The difference between this embodiment and embodiment 1 is that the printing process parameters in step (4) are different, as follows: The printing process parameters in this embodiment are as follows: laser power 240W, scanning speed 500mm / s, layer thickness 0.02mm, scanning spacing 0.07mm, checkerboard scanning, and interlayer rotation angle 45°. After each alloy layer is laser printed, it is immediately remelted in situ using the same laser scanning parameters. The rest of the process is the same.

[0042] Example 4 The difference between this embodiment and embodiment 1 is that the printing process parameters in step (4) are different, as follows: The printing process parameters in this embodiment are as follows: laser power 360W, scanning speed 800mm / s, layer thickness 0.03mm, scanning spacing 0.09mm, checkerboard scanning, and interlayer rotation angle 67°. After each alloy layer is laser printed, it is immediately remelted in situ using the same laser scanning parameters. The rest of the process is the same.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that in step (4), after each alloy layer is laser printed, it is not remelted, but the rest is the same.

[0044] Comparative Example 2 The difference between this comparative example and Example 1 is that the internal purging and cleaning process of step (6) is missing, while the rest are the same.

[0045] Comparative Example 3 The difference between this comparative example and Example 1 is that the heat treatment process of step (7) is missing, while the rest are the same.

[0046] Performance testing: (1) The density of the copper alloy liquid flow radiator was measured according to Archimedes' water displacement method.

[0047] (2) Use an endoscope to check whether there is residual powder inside the microchannel.

[0048] (3) Sealing test: Pass distilled water into the radiator and maintain the pressure at 20 bar for 30 minutes. Observe whether there is any leakage in the radiator.

[0049] (4) Conduct the thermal resistance voltage drop test according to GB / T8446.2-2022. For specific on-site conditions, please refer to [the relevant documentation]. Figure 4 The image shows a test of the heat dissipation performance of a copper alloy liquid cooler. It illustrates how the thermal performance of the cooler is measured by connecting wires to both ends. The test liquid flow rate is 3.8 L / min, and the liquid temperature is 20°C, measuring the thermal resistance and pressure drop.

[0050] Some of the test results are shown in Table 1.

[0051] Table 1 The external three-dimensional structure diagram of the copper alloy liquid-cooled heat sink obtained in Example 1 is shown below. Figure 1 As shown, the actual object is as follows: Figure 2As shown, its internal structural diagram is as follows: Figure 3 As shown, the microchannels of the internal triple periodic minimal surface (TPMS) fin structure can increase the heat dissipation area and improve heat dissipation performance.

[0052] As shown in Examples 1-4, the performance test results of the copper alloy microchannel liquid coolers in Examples 1-4 indicate that: the density reached 98.2%-99.2% according to Archimedes' displacement method; endoscopic inspection revealed no residual powder inside the microchannels of the liquid coolers in Examples 1-4, and the flow channels were unobstructed; the sealing test showed no leakage in the liquid coolers of Examples 1-4. According to GB / T8446.2-2022, the thermal resistance and pressure drop test was conducted. At a flow rate of 3.8 L / min and a liquid temperature of 20℃, the thermal resistance of the liquid coolers in Examples 1-4 was measured to be 0.0068-0081℃ / W, and the pressure drop was 262.81-278.22 kPa, indicating that the heat dissipation efficiency meets the actual requirements.

[0053] Compared with Example 1, Comparative Example 1 did not undergo in-situ remelting between layers. As a result, a large number of pores, lack of fusion and microcracks were generated inside the workpiece, the density decreased significantly, the thermal resistance and pressure drop increased significantly, and leakage occurred in the sealing test. This shows that in-situ remelting can effectively eliminate forming defects, improve density, improve heat dissipation performance and ensure sealing reliability.

[0054] Compared with Example 1, Comparative Example 2 lacks an internal purging and cleaning process, and the residual powder in the liquid flow channel cannot be removed, causing channel blockage and a significant increase in pressure drop and thermal resistance.

[0055] Compared with Example 1, Comparative Example 3 did not undergo heat treatment. The residual stress inside the workpiece was not released, the dimensional stability decreased, and the thermal resistance and pressure drop were slightly higher than those of Example 1. This indicates that heat treatment can further release stress and improve the dimensional accuracy and performance stability of the product.

[0056] Finally, 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 the scope of protection of the present invention. 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 essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a copper alloy liquid-cooled heat sink, characterized in that, Includes the following steps: S1. Place copper alloy powder and substrate in a laser additive manufacturing equipment, and print alloy layers on the substrate layer by layer according to the liquid cooling heat sink model with liquid flow channels and its slicing path. Each alloy layer is printed and constructed in sequence, including copper alloy powder laying, laser printing and remelting. After printing, the substrate is cooled and removed to obtain a printed alloy part; the printed alloy part has a liquid flow channel; S2. Compressed air is used to purge the liquid flow channels in the printed alloy part, and then the part is cleaned and dried to obtain the cleaned printed alloy part. S3. The cleaned printed alloy part is heat-treated in an inert gas atmosphere to obtain a copper alloy liquid-cooled heat sink.

2. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S1, the laser printing process includes the following parameters: the layer thickness is 0.02-0.03 mm, the laser wavelength is 1000-1100 nm, the laser power is 200-400 W, the scanning speed is 500-800 mm / s, the scanning spacing is 0.07-0.1 mm, and the scanning method is "Z" shaped scanning or "chessboard" scanning; and / or, the angle between layers when printing the alloy layer layer by layer is 40°-70°.

3. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S1, the remelting process includes the following process parameters: laser wavelength of 1000-1100nm, laser power of 200-400W, scanning speed of 500-800mm / s, scanning spacing of 0.07-0.1mm, and scanning method of "Z" pattern scanning or "chessboard" scanning.

4. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S3, the heat treatment temperature is 400-550℃, and the heat treatment time is 1-6h.

5. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S2, the purging pressure is 0.1-1 MPa, the purging time is 5-180 min, and the purging method is as follows: first, the surface of the printed alloy part is purged with compressed air; then, compressed air is introduced into the liquid flow channel from the inlet or outlet of the liquid flow channel on the printed alloy part through the nozzle for purging, and the purging is carried out alternately from the inlet and outlet of the liquid flow channel.

6. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S1, the liquid flow channel in the printed alloy part includes a fin structure with a triple periodic minimal curved surface, and the fin thickness is 2-5 mm.

7. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S1, the copper alloy powder comprises the following components by mass percentage: Cr 0.5%-1.5%, Zr 0.05%-0.3%, with the balance being Cu and unavoidable impurities.

8. The method for preparing the copper alloy liquid-cooled heat sink as described in claim 1, characterized in that, In step S1, the loose packing density of the copper alloy powder is 4.0-4.5 g / cm³. 3 The fluidity is 15-25s / 50g, D10 is 20-25μm, D50 is 30-45μm, D90 is 50-55μm, and the oxygen content is less than or equal to 500ppm; And / or, in step S1, the copper alloy powder is also subjected to vacuum drying and sieving; And / or, in step S1, the substrate is further subjected to polishing, cleaning and vacuum drying.

9. A copper alloy liquid-cooled heat sink, characterized in that, It is prepared by the method of any one of claims 1-8 for the preparation of copper alloy liquid-cooled heat sink.

10. The copper alloy liquid-cooled heat sink as described in claim 9, characterized in that, The density is 98.0%-99.9%, and / or, at a liquid flow rate of 3.8 L / min and a liquid temperature of 20 °C, the thermal resistance of the liquid-cooled heat sink is 0.006-009 °C / W, and the pressure drop is 262-279 kPa.

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