A method of alloy brazing connection based on laser modification and a brazed product

Abstract

This invention relates to the field of brazing technology and discloses a laser-modified alloy brazing joining method and brazed products. By using a laser to modify the surface of cemented carbide, uniform and flat "V-shaped" grooves are generated, improving the wettability of the brazing filler metal on the cemented carbide surface and increasing the joint strength of the cemented carbide brazing. This invention achieves high-performance joints of cemented carbide of the same material through the construction of the groove structure, the selection of Ag-Cu-Ti active brazing filler metal, and the synergistic effect of brazing process parameters. Furthermore, there is a quantitative relationship between the laser-modified groove specifications and the reaction layer thickness; specific groove specifications, brazing filler metal, and brazing parameters can synergistically improve the joint strength of the brazed alloy of the same material. The brazed products exhibit the best overall performance when the laser power is 25W, the brazing temperature is 865℃, and the holding time is 9min.

Description

Technical Field

[0001] This invention relates to the field of brazing technology, and specifically to a laser-modified alloy brazing connection method and brazed products. Background Technology

[0002] The surface condition of a material directly affects its wettability. Therefore, surface modification has become an important means to improve the wettability and spreadability of material surfaces. Currently, surface texture processing methods mainly include direct laser processing, laser interferometry, plasma processing, and machining.

[0003] Currently, to further improve the connection strength of brazed joints, existing technologies utilize laser surface modification. For example, Li et al. improved the wettability of AlSi5 brazing filler metal on Ti6Al alloy by creating microtextures on the alloy surface using laser and varying the spacing between the grooves to enhance wettability. They found that wettability was significantly improved only when the spacing was greater than 0.25 mm, with the best result achieved at a spacing of 0.5 mm. Zhang et al. improved the hydrophilicity of ceramic surfaces through femtosecond laser processing and, after high-temperature decomposition and oxidation, formed a recast layer on the surface. This layer, when brazed with aluminum alloys, resulted in a new IMC layer. Results showed that a laser power of 24 W increased the shear strength to 44.1 MPa. Wang et al. improved the surface roughness of AlSi304 stainless steel by combining laser texturing and electroplating, promoting mechanical bonding and resulting in an average shear strength increase of 8.5% compared to untreated AlSi304 stainless steel joints. Yang et al. increased the thickness of the IMC layer at the deeper parts of the steel surface by drilling grooves of different depths on the steel surface, thereby changing the fracture mode from brittle fracture to ductile fracture and achieving a shear strength of 111 MPa in the brazed joint. These experimental results demonstrate that using a laser can improve the wettability of the material surface, thus enhancing the shear strength of the brazed joint.

[0004] Existing technologies for improving brazed joints using laser modification typically focus on studying the brazing mechanism and process of laser-modified dissimilar materials. Due to the difference in thermal expansion coefficients between dissimilar materials, this difference causes significant interfacial residual stress during the joint cooling process. Therefore, constructing groove structures on the surface of the dissimilar materials can increase mechanical interlocking and regulate interfacial residual stress, while simultaneously improving the surface wettability of the dissimilar materials, thereby enhancing the joint strength.

[0005] However, when laser-modified homogeneous materials are brazed together, there is no difference in the coefficient of thermal expansion between the materials, and the contribution of mechanical interlocking to strength is far less than that of interfacial metallurgical bonding. In this case, the groove structure generated by laser modification mainly affects the joint performance by influencing the diffusion behavior of active elements in the brazing filler metal and the formation and growth of the interfacial reaction layer. When homogeneous materials are brazed together using active brazing filler metal, the joint strength is greatly affected by the thickness and continuity of the reaction layer between the brazing filler metal and the base material. Therefore, surface laser modification of dissimilar materials is not suitable for brazing with homogeneous materials. Conversely, an unsuitable laser modification process can result in grooves that are too wide, too deep, too narrow, or too shallow, thus affecting the formation of the reaction layer, which is directly related to the joint strength. When the groove is too shallow or too narrow, the active elements are insufficiently enriched, the reaction layer is too thin, and the interfacial metallurgical bonding is inadequate; when the groove is too deep or too wide, the active elements are excessively enriched, resulting in an excessively thick reaction layer, which in turn reduces the joint strength due to the thickening of the brittle phase. Therefore, there is an optimal range of groove specifications in brazing of the same material. This range must be matched with the diffusion depth of the active brazing filler metal and the brazing process parameters. Neither too thick nor too thin a reaction layer can achieve the best joint strength after brazing of the same material.

[0006] It is evident that while current technologies have focused on brazing dissimilar materials such as laser-modified ceramics, laser-modified aluminum alloys, and laser-modified steel substrates, research on brazing processes for laser-modified homogeneous materials, particularly laser-modified cemented carbide, is scarce. Specifically, there is a lack of systematic research on the relationship between the interfacial reaction layer formed between the cemented carbide surface and the brazing filler metal, the laser modification process, and the brazing process during laser-modified cemented carbide brazing. Therefore, it is necessary to conduct process screening for laser-modified cemented carbide surface brazing. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a laser-modified alloy brazing connection method and brazed products. By using a laser to modify the surface of cemented carbide, uniform and flat "V-shaped" grooves are generated, improving the wettability of the brazing filler metal on the cemented carbide surface and increasing the connection strength of the cemented carbide brazing. This invention achieves high-performance connection of cemented carbide joints of the same material through the synergistic effect of groove structure construction, selection of Ag-Cu-Ti active brazing filler metal, and screening of brazing process parameters. Furthermore, after screening the laser modification process and brazing process, it was found that there is a quantitative relationship between the laser-modified groove specifications and the reaction layer thickness. Specific groove specifications, brazing filler metal, and brazing parameters can synergistically improve the joint strength of the cemented carbide brazing alloy.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A laser-modified alloy brazing joining method and brazed products, comprising the following steps: Step (1): Grind the cemented carbide; laser modify the ground surface of the cemented carbide, process the groove structure on the ground surface of the cemented carbide, clean, dry, and then pickle the surface to obtain the laser modified cemented carbide. The conditions for laser modification treatment are as follows: laser power of 1-50W, spacing of 0.005-0.5mm, speed of 50-150mm / s, frequency of 1-50KHz, pulse width of 2-500ns, and wavelength of 248-1065nm; the width of the trench structure is 32.8-65.9μm, and the depth is 42.3-107.6μm. Step (2): The cemented carbide and the laser-modified cemented carbide are brazed together using Ag-Cu-Ti solder paste to obtain the brazed product.

[0009] Preferably, in step (1), the mass percentage of each component in the cemented carbide is: 89% WC, 10% Co and 1% other impurities.

[0010] Preferably, in step (1), the conditions for laser modification are: laser power of 25W, spacing of 0.5mm, speed of 80mm / s, frequency of 20KHz, pulse width of 100ns, and wavelength of 1065nm; the width of the trench structure is 59.4μm and the depth is 74.1μm.

[0011] Preferably, in step (1), the pickling operation includes wiping the surface of the cemented carbide with aqua regia for 30s-1min.

[0012] Preferably, in step (2), the brazing operation includes: applying Ag-Cu-Ti solder paste to the modified surface of the laser-modified cemented carbide, placing the polished surface of another cemented carbide on the Ag-Cu-Ti solder paste, aligning the two cemented carbide surfaces, squeezing out a uniform amount of solder paste on all four sides, and finally placing the assembled sample into a vacuum brazing furnace for brazing. After brazing is completed, the sample is cooled with the furnace.

[0013] Preferably, in step (2), the mass percentage of each component in the Ag-Cu-Ti solder paste is: 23-50% Cu, 2-5% Ti, and the remainder is Ag.

[0014] Furthermore, in step (2), the mass percentage of each component in the Ag-Cu-Ti solder paste is: 68.8% Ag, 26.7% Cu, and 4.5% Ti; the coating thickness of the Ag-Cu-Ti solder paste is 0.06-0.1 mm.

[0015] Preferably, in step (2), the brazing conditions are: holding at 835-880℃ for 5-13 minutes, with a vacuum degree of 7×10⁻⁶. -4 Pa to 1×10 -3 Pa, heating rate is 1-20℃ / min, cooling rate is 1-20℃ / min.

[0016] Preferably, a brazed product is prepared using the laser-modified alloy brazing joining method described above.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention optimizes the shear strength of brazed carbide joints by laser-treating the surface of cemented carbide to create a regular groove structure, followed by vacuum brazing using Ag-Cu-Ti solder paste. This invention achieves high-performance connections between cemented carbide joints of the same material through the construction of the groove structure, the selection of Ag-Cu-Ti active solder, and the synergistic effect of brazing process parameters. Furthermore, after screening the laser modification and brazing processes, it was found that there is a quantitative relationship between the laser-modified groove specifications and the reaction layer thickness; specific groove specifications, solder, and brazing parameters can synergistically improve the joint strength of brazed carbide joints of the same material.

[0018] 2. This invention uses a laser to generate uniform and flat "V-shaped" grooves on the surface of cemented carbide. After nanosecond laser treatment, the Fe3C peak on the cemented carbide surface becomes increasingly higher. Fe3C can improve wettability and enhance the metallurgical bonding strength between the brazing filler metal and the cemented carbide, thereby improving the shear strength of the AK40 cemented carbide-AK40 cemented carbide brazed joint. As the laser power increases, the spreading area of ​​the brazing filler metal on the cemented carbide surface increases from 0.28 cm². 2 Increased to 0.38cm 2 This is because the surface trench structure after laser treatment effectively increases the contact area between the solder paste and the cemented carbide. After brazing with active solder, CuTiIMC layer + Ag[s,s] + Cu[s,s] + Ag-Cu eutectic phases are formed in the trenches and on the laser-modified AK40 cemented carbide side, thereby improving the joint strength. However, when the laser modification power is further increased, and the trench width and depth are further increased, the solder paste spreading area decreases from 0.38 cm². 2 Reduced to 0.29cm 2The trend shows an initial increase followed by a decrease. This is because excessively deep trenches may prevent the brazing filler metal from completely filling the bottom of the trench, thus reducing the effective contact area. Furthermore, the excessively thick CuTiIMC layer formed after brazing with active brazing filler metal acts as a brittle layer, leading to a decrease in joint strength. It is evident that the trenches not only increase the wetting area but also precisely control the reaction layer thickness, thereby improving joint strength. Appropriate thickening of the CuTiIMC layer enhances the shear strength of the cemented carbide joint; however, an excessively thick CuTiIMC layer may actually cause the brazed joint to be prone to brittle fracture, resulting in a decrease in joint strength.

[0019] This invention screened the optimal process parameters for laser modification. When the laser power was 25W, the spacing was 0.5mm, the speed was 80mm / s, the frequency was 20kHz, the pulse width was 100ns, and the wavelength was 1065nm, the width of the trench structure constructed on the cemented carbide surface was 59.4μm, the depth was 74.1μm, and the maximum solder paste spreading area was 0.38cm². 2 .

[0020] Meanwhile, this invention also screened brazing process parameters suitable for brazing the same material. Specifically, the composition of the brazed cemented carbide joint in this invention is AK40 cemented carbide / TiC+CuTi / Ag[s,s]+Cu[s,s]+Ag-Cu eutectic+Fe2Ti+Ni3Ti / CuTi+TiC / AK40 cemented carbide. As the brazing temperature and holding time increase, the TiC layer at the AK40 cemented carbide becomes thicker, the CuTi layer becomes more continuous and thicker, and the microstructure of the Fe2Ti and Ni3Ti phases gradually coarsens. With the growth of these hard and brittle phases, the shear strength of the joint also changes. When the brazing temperature increases from 835℃ to 880℃, the shear strength of the joint first increases and then decreases with increasing temperature. When the holding time increases from 5 min to 13 min, the shear strength of the joint first increases and then decreases with increasing time. Therefore, the optimal brazing process parameters are determined to be a brazing temperature of 865℃ and a holding time of 9 min.

[0021] In summary, this invention constructs a groove structure on the surface of cemented carbide by employing optimal process parameters for laser modification, and simultaneously selects Ag-Cu-Ti active brazing filler metal for brazing. Furthermore, the brazing process is optimized and screened to ensure that the laser-modified cemented carbide exhibits the best overall performance after brazing. This verifies that there is a quantitative relationship between the specifications of the laser-modified groove and the thickness of the reaction layer. Specific groove specifications, brazing filler metal, and brazing parameters can synergistically improve the joint strength of brazed alloys made of the same material, realizing the transformation from brittle fracture at the interface to ductile fracture within the matrix at the joint of the brazed product. Attached Figure Description

[0022] Figure 1 These are surface texture morphology images and three-dimensional morphology images of the laser-modified cemented carbide prepared in Examples 1-3 of the present invention; in the figures, (a1) is a top view of the surface texture morphology of the laser-modified cemented carbide in Example 1, (a2) is a side view of the surface texture morphology of the laser-modified cemented carbide in Example 1, (b1) is a top view of the surface texture morphology of the laser-modified cemented carbide in Example 2, (b2) is a side view of the surface texture morphology of the laser-modified cemented carbide in Example 2, (c1) is a top view of the surface texture morphology of the laser-modified cemented carbide in Example 3, and (c2) is a side view of the surface texture morphology of the laser-modified cemented carbide in Example 3; Figure 2 This is a bar chart showing the dimensions of the laser-modified cemented carbide surface grooves prepared in Examples 1-3 of this invention; Figure 3 These are XRD phase analysis diagrams of the laser-modified cemented carbide surfaces prepared in Examples 1-3 of this invention; Figure 4 The figures show top views of Ag-Cu-Ti solder paste brazed on laser-modified cemented carbide substrates prepared in Examples 1-3 of this invention and on unmodified cemented carbide substrates in Comparative Example 1, after the solder paste has solidified. In the figures, (a) is a top view of Ag-Cu-Ti solder paste brazed on unmodified cemented carbide substrates in Comparative Example 1, after the solder paste has solidified; (b) is a top view of Ag-Cu-Ti solder paste brazed on laser-modified cemented carbide substrates in Example 1, after the solder paste has solidified; (c) is a top view of Ag-Cu-Ti solder paste brazed on laser-modified cemented carbide substrates in Example 2, after the solder paste has solidified; and (d) is a top view of Ag-Cu-Ti solder paste brazed on laser-modified cemented carbide substrates in Example 3, after the solder paste has solidified. Figure 5 These are images showing the wetting angles of the surfaces of laser-modified cemented carbide prepared with solder paste in Examples 1-3 of this invention and the surface of cemented carbide without laser modification in Comparative Example 1; in the images, (a) is an image showing the wetting angle of the surface of cemented carbide without laser modification in Comparative Example 1, (b) is an image showing the wetting angle of the surface of cemented carbide with solder paste prepared with laser modification in Example 1, (c) is an image showing the wetting angle of the surface of cemented carbide with solder paste prepared with laser modification in Example 2, and (d) is an image showing the wetting angle of the surface of cemented carbide with solder paste prepared with laser modification in Example 3; Figure 6 These are CT images of the brazed product prepared in Comparative Example 1 of this invention; in the figures, (a) is a macroscopic view of the CT sample of the brazed product prepared in Comparative Example 1, and (b) is an enlarged view of the CT sample of the brazed product prepared in Comparative Example 1. Figure 7These are microstructure images of the joints of brazed products prepared in Comparative Examples 1-4 of this invention; in the figures, (a) is a microstructure image of the joint of the brazed product prepared in Comparative Example 2, (b) is a microstructure image of the joint of the brazed product prepared in Comparative Example 3, (c) is a microstructure image of the joint of the brazed product prepared in Comparative Example 1, and (d) is a microstructure image of the joint of the brazed product prepared in Comparative Example 4. Figure 8 These are microstructure images of the joints of brazed products prepared in Comparative Examples 1 and 5-6 of this invention; in the figures, (a) is a microstructure image of the joint of the brazed product prepared in Comparative Example 5, (b) is a microstructure image of the joint of the brazed product prepared in Comparative Example 1, and (c) is a microstructure image of the joint of the brazed product prepared in Comparative Example 6. Figure 9 This is a microstructure diagram of the interface of the brazed product prepared in Comparative Example 1 of this invention; in the figure, (a) is a microstructure diagram, (b) is a magnified image of the cemented carbide / brazing filler metal interface, (c) is a magnified image of the brazing filler metal / cemented carbide interface, and (d) to (i) are elemental distribution diagrams. Figure 10 These are microstructure diagrams of the brazed joints of the brazed products prepared in Examples 1-3 of this invention; in the figures, (a) is a microstructure diagram of the brazed joint of the brazed product prepared in Example 1, (b) is a microstructure diagram of the brazed joint of the brazed product prepared in Example 2, and (c) is a microstructure diagram of the brazed joint of the brazed product prepared in Example 3. Figure 11 These are line scan results of the brazed products prepared in Examples 1-3 and Comparative Example 1 of this invention; in the figures, (a) is a line scan result of the brazed product prepared in Comparative Example 1, (b) is a line scan result of the brazed product prepared in Example 1, (c) is a line scan result of the brazed product prepared in Example 2, and (d) is a line scan result of the brazed product prepared in Example 3. Figure 12 These are comparative diagrams of the shear strength at the joint of the brazed products prepared in Comparative Examples 1-6 of this invention; in the diagram, (a) is a comparative diagram of the shear strength at the joint of the brazed products prepared in Comparative Examples 1-4, and (b) is a comparative diagram of the shear strength at the joint of the brazed products prepared in Comparative Examples 1 and 5-6. Figure 13 This is a microhardness distribution diagram at the joint of the brazed product prepared in Comparative Example 1 of this invention; Figure 14 This is a comparison diagram of the shear strength of the brazed joints of the brazed products prepared in Comparative Example 1 and Examples 1-3 of this invention; Figure 15These are fracture surface morphology diagrams of the joints of brazed products prepared in Comparative Examples 1-4 of this invention; in the figures, (a) is a fracture surface morphology diagram of the joint of brazed products prepared in Comparative Example 2, (b) is a fracture surface morphology diagram of the joint of brazed products prepared in Comparative Example 3, (c) is a fracture surface morphology diagram of the joint of brazed products prepared in Comparative Example 1, (d) is a fracture surface morphology diagram of the joint of brazed products prepared in Comparative Example 4, (e) is an enlarged view of the fracture surface morphology of the joint of brazed products prepared in Comparative Example 2, (f) is an enlarged view of the fracture surface morphology of the joint of brazed products prepared in Comparative Example 3, (g) is an enlarged view of the fracture surface morphology of the joint of brazed products prepared in Comparative Example 4, and (g1) to (g5) are elemental distribution diagrams of the fracture surface of the joint of brazed products prepared in Comparative Example 4. Figure 16 These are fracture surface morphology diagrams of the joints of the brazed products prepared in Comparative Examples 1 and 5-6 of this invention; in the figures, (a) is a fracture surface morphology diagram of the joint of the brazed product prepared in Comparative Example 5, (b) is a fracture surface morphology diagram of the joint of the brazed product prepared in Comparative Example 1, and (c) is a fracture surface morphology diagram of the joint of the brazed product prepared in Comparative Example 6. Figure 17 These are XRD test images of the fracture surfaces of the joints of the brazed products prepared in Comparative Examples 1-6 of this invention; in the figures, (a) is an XRD test image of the fracture surfaces of the joints of the brazed products prepared in Comparative Examples 1-4, and (b) is an XRD test image of the fracture surfaces of the joints of the brazed products prepared in Comparative Examples 1 and 5-6. Figure 18 These are fracture surface morphology diagrams of the brazed products prepared in Example 2 and Comparative Example 1 of this invention; in the figures, (a) is the original cemented carbide fracture surface morphology diagram of the brazed product prepared in Comparative Example 1, (b) is the cemented carbide laser fracture surface morphology diagram of the brazed product prepared in Example 2, (c) is the cemented carbide non-laser fracture surface morphology diagram of the brazed product prepared in Example 2, and (d) to (h) are elemental distribution diagrams of the cemented carbide laser fracture surface of the brazed product prepared in Example 2. Figure 19 This is a schematic diagram of the joint fracture path of the brazed products prepared in Example 2 and Comparative Example 1 of the present invention; in the figure, (a) is a schematic diagram of the joint fracture path of the brazed product prepared in Comparative Example 1, and (b) is a schematic diagram of the joint fracture path of the brazed product prepared in Example 2. Figure 20These are fracture surface morphology diagrams of the brazed products prepared in Examples 1-3 of this invention; in the figures, (a1) is the laser fracture surface morphology diagram of the brazed product prepared in Example 1, (a2) is the non-laser fracture surface morphology diagram of the brazed product prepared in Example 1, (b1) is the laser fracture surface morphology diagram of the brazed product prepared in Example 2, (b2) is the non-laser fracture surface morphology diagram of the brazed product prepared in Example 2, (c1) is the laser fracture surface morphology diagram of the brazed product prepared in Example 3, and (c2) is the non-laser fracture surface morphology diagram of the brazed product prepared in Example 3. Figure 21 This is an elemental distribution diagram of the joint fracture surface of the brazed products prepared in Examples 1-3 of this invention. In the diagram, (a1) to (a5) are... Figure 20 The element distribution diagram of the joint fracture surface in (a1) is shown, and (b1) to (b5) are... Figure 20 Distribution diagram of joint fracture elements in (c1); Figure 22 This is a schematic diagram of the surface of the laser-modified cemented carbide and an assembly schematic diagram of the brazed product in this invention; Figure 23 This is a schematic diagram of the brazing mechanism when preparing brazed products in this invention. The diagram illustrates that as the brazing temperature increases, atoms in the cemented carbide and solder paste diffuse and combine. (a) to (d) are schematic diagrams of atomic diffusion and combination during the original cemented carbide brazing, and (e) is a schematic diagram of the diffusion and combination of brazed atoms after laser modification in the presence of grooves. Detailed Implementation

[0023] The present invention will be further illustrated below through specific embodiments. The following embodiments are specific implementations of the present invention, but the implementation of the present invention is not limited to the following embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

[0024] Example 1 This embodiment discloses a laser-modified alloy brazing joining method, including the following steps: Step (1): Grind a 6×6×5mm cemented carbide (AK40 cemented carbide, provided by Wuhu Lingyi Precision Tools Manufacturing Co., Ltd. of Anhui Province, with a composition of 89% WC, 10% Co and 1% other impurities); modify the surface of the cemented carbide by laser marking machine with a laser power of 12.5W, a spacing of 0.5mm, a speed of 80mm / s, a frequency of 20KHz, a pulse width of 100ns, and a wavelength of 1065nm. Groove structure is processed on the grinding surface of the cemented carbide, and it is cleaned in acetone and ethanol, dried, and then its surface is acid-washed. Aqua regia (prepared by mixing 36wt% concentrated hydrochloric acid and 68wt% concentrated nitric acid in a volume ratio of 3:1) is used to wipe the surface of the cemented carbide for 30s to obtain laser-modified cemented carbide. The trench structure has a width of 32.8 μm and a depth of 42.3 μm; Step (2): Apply Ag-Cu-Ti solder paste to the modified surface of the laser-modified cemented carbide using screen printing, with a thickness of 0.08 mm. Place another 6×6×5 mm polished surface of cemented carbide on the Ag-Cu-Ti solder paste, aligning the two cemented carbide surfaces. Extrude a uniform amount of solder paste evenly from all four sides. Finally, place the assembled sample into a vacuum brazing furnace for brazing. The brazing conditions are: holding at 865℃ for 9 minutes, with a vacuum degree of 1×10⁻⁶. -3 Pa, heating rate of 15℃ / min, cooling rate of 10℃ / min, after brazing, cooling with the furnace to obtain brazed product; The Ag-Cu-Ti solder paste contains the following mass percentages of each component: 68.8% Ag, 26.7% Cu, and 4.5% Ti.

[0025] Example 2 The difference from Example 1 is that the laser power in step (1) is changed to 25W; the width of the groove structure in the laser-modified cemented carbide is changed to 59.4μm and the depth is changed to 74.1μm; other parameters and conditions are the same as in Example 1.

[0026] Example 3 The difference from Example 1 is that the laser power in step (1) is changed to 37.5W; the width of the groove structure in the laser-modified cemented carbide is changed to 65.9μm and the depth is changed to 107.6μm; other parameters and conditions are the same as in Example 1.

[0027] Comparative Example 1 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; other parameters and conditions are the same as in Example 1.

[0028] Comparative Example 2 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; the brazing conditions were changed to holding at 835°C for 9 minutes; and the other parameters and conditions were the same as in Example 1.

[0029] Comparative Example 3 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; the brazing conditions were changed to holding at 850°C for 9 minutes; and the other parameters and conditions were the same as in Example 1.

[0030] Comparative Example 4 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; the brazing conditions were changed to holding at 880°C for 9 minutes; and the other parameters and conditions were the same as in Example 1.

[0031] Comparative Example 5 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; the brazing conditions were changed to holding at 865°C for 5 minutes; and the other parameters and conditions were the same as in Example 1.

[0032] Comparative Example 6 The difference from Example 1 is that the cemented carbide used in step (2) was not laser modified; the brazing conditions were changed to holding at 865°C for 13 minutes; and the other parameters and conditions were the same as in Example 1.

[0033] Experimental data characterization and performance testing In Examples 1-3, after laser etching and acid etching, microgroove structures of different sizes were successfully fabricated on the surface of AK40 cemented carbide. The surface depth maps and three-dimensional morphologies from different viewing angles are shown below. Figure 1 As shown. During the laser process, the material undergoes instantaneous melting, vaporization, and rapid cooling to form the groove. No obvious burrs, spatter, or recast layer defects appear on the surface of the groove, resulting in good surface quality and an overall regular V-shaped groove morphology.

[0034] like Figure 2 As shown, as the laser power increases from 12.5W to 37.5W, the geometric dimensions of the trench exhibit a significant increasing trend: the trench width increases from 32.8μm to 65.9μm, an increase of up to 101%; the trench depth increases from 42.3μm to 107.6μm, an increase of up to 154%. This indicates that within the parameter range of Examples 1-3 of this invention, the laser power has a significant regulatory effect on both the width and depth of the trench; the higher the power, the greater the amount of material removed, and the larger the trench size accordingly.

[0035] like Figure 3As shown, XRD phase analysis was performed on the original AK40 cemented carbide and the laser-modified cemented carbide prepared in Examples 1-3. The comparison revealed that the intensity of the Fe3C diffraction peak in the phase spectrum gradually increased with increasing laser power, reaching its peak at a laser power of 25W. The formation and enrichment of the Fe3C phase can effectively improve the wettability of the solder on the cemented carbide surface, promote atomic diffusion and interfacial reaction between the solder and the matrix, and thus enhance the metallurgical bonding strength between the solder and the cemented carbide matrix.

[0036] Figure 4 Top views of Ag-Cu-Ti solder paste after solidification, showing the results of brazing Ag-Cu-Ti solder paste onto laser-modified cemented carbide substrates prepared in Examples 1-3 and on unmodified cemented carbide substrates in Comparative Example 1. On the untreated cemented carbide surface, the resolidified Ag-Cu-Ti solder paste has an approximately circular shape and a spreading area of ​​approximately 0.28 cm². 2 After the cemented carbide surface was treated with laser, the solder paste spreading area was 0.32 cm². 2 0.38cm 2 and 0.29cm 2 The trend shows an initial increase followed by a decrease. When the laser power is 25W, the solder paste has the largest spreading area, which is about 35.7% larger than the spreading area of ​​the untreated surface.

[0037] In the brazing process of cemented carbide, the wetting and spreading properties of the solder paste on the base material surface are a key factor determining the quality of the interfacial bonding, and the wetting angle is the core indicator for quantitatively characterizing this property. Therefore, testing the wetting angle of the solder paste on the AK40 cemented carbide surface can directly reflect the wettability, interfacial affinity, and atomic diffusion ability between the solder paste and the base material, providing an important basis for evaluating the rationality of the brazing process and predicting the joint strength. Figure 5 The wetting angle variation of the laser-modified cemented carbide surface prepared by Ag-Cu-Ti solder paste in Examples 1-3, such as Figure 5 As shown in (a), the wetting angle of the untreated cemented carbide surface is 63.6°, and wetting can occur when the wetting angle is less than 90°; Figure 5 As shown in (b), (c), and (d), when the laser power increases from 12.5W to 37.5W, the wetting angles are 46.9°, 36.2°, and 48.9°, respectively, showing a trend of first increasing and then decreasing. When the laser power is 25W, the wetting angle is the smallest at 36.2°, which is about 43.1% lower than the wetting angle of the untreated surface. When the wetting angle is the smallest, the solder paste has the best wetting performance on the substrate. When the weight of the solder paste is constant, the larger the solder paste spreading area, the smaller the wetting angle.

[0038] Figure 6CT images of the brazed specimens prepared in Comparative Example 1, from... Figure 6 As can be seen from the magnified CT image in (b), the brazing seam is dense and without pores, indicating that the AK40 cemented carbide and Ag-Cu-Ti solder paste achieved a good metallurgical bond under the process of brazing temperature of 865℃ and holding time of 9min.

[0039] Figure 7 This is a microstructure diagram of the joint of AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide in the brazed products prepared in Comparative Examples 1-4. As the temperature increases, layers II and V become more continuous. This is because when the brazing temperature is too low, the reaction is insufficient, resulting in discontinuous reaction layers and poor bonding. With increasing temperature, the filler metal and base metal react fully, making the reaction layers more continuous. Furthermore, layers I, II, IV, and V thicken with increasing temperature. This is because the diffusion of Ti into the base metal becomes more intense with increasing brazing temperature, leading to thicker reaction layers and the formation of a TiC layer in layers I and IV. Since the TiC layer is brittle, its thickness can lead to… The bonding performance of the joint deteriorates. The remaining Ti atoms accumulated in AK40 cemented carbide / Ag-Cu-Ti and Ag-Cu-Ti / AK40 cemented carbide react with Cu atoms to form a CuTi layer. As long as the volume fraction of the generated CuTi is not high and its distribution is uniform, it helps to consume excess Ti atoms, adjust the composition and properties of the joint area, and prevent further interdiffusion between other elements in the upper layer and the lower layer material, thereby stabilizing the interface. However, it is still a brittle layer in essence, so when the CuTi becomes thicker, it will also affect the bonding performance of the joint. As the brazing temperature increases, the Ag-Cu eutectic structure in layer III becomes richer. The phase interface between the α phase and β phase can effectively hinder dislocation movement, producing a significant strengthening effect. Compared with a single solid solution, the eutectic structure can usually provide higher strength, hardness and a certain degree of plasticity at the same time, giving the joint better impact resistance and vibration fatigue resistance. However, when the brazing temperature is 880℃, the distribution of the Ag-Cu eutectic structure becomes uneven. This is because the CuTi layer in layer II becomes thicker, which consumes too many Cu atoms, resulting in an uneven distribution of the Ag-Cu eutectic structure in layer III.

[0040] Figure 8 The microstructure of the AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide interface in the brazed products prepared in Comparative Examples 1 and 5-6 is shown below. Figure 8As shown in (a)-(c), as the holding time increases, the thickness of the TiC layer in layer I gradually increases, and the CuTi layers in layers II and V also gradually thicken. The Ag-Cu eutectic structure in layer III becomes increasingly abundant and its distribution becomes more uniform. However, when the holding time is increased to 13 min, due to the thickening of layer II, Cu atoms are excessively consumed by the formation of the CuTi layer in layer II, leading to an uneven distribution of the Ag-Cu eutectic structure. This also indicates that the holding time has the same effect as the brazing temperature. It is noteworthy that with the increase of the holding time, the microstructure of the Fe2Ti and Ni3Ti phases gradually coarsens. Both Fe3Ti and Ni3Ti phases are brittle phases, and this coarsening leads to early failure of the joint performance, resulting in a decrease in shear strength at a holding time of 13 min. Increasing the holding time induces the ripening and coarsening of brittle phases, increases phase size, reduces grain boundaries, and intensifies stress concentration, significantly reducing the joint's plasticity and strength.

[0041] Table 1 Figure 9 The elemental composition (at.%) of each point in the middle

[0042] Figure 9 The image shows the interfacial microstructure of the AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide in the brazed product prepared in Comparative Example 1. The morphology shows a dense, non-porous microstructure. The EDS of the brazed seam is as follows: Figure 9 As shown in (d)-(i), C, Fe, and Ni atoms in the base material diffused and overlapped with Ti atoms in the solder. At the AK40 alloy / solder interface, Ti atoms were continuously and linearly enriched, and Ti atoms in the solder diffused into the base material. This is because Ti atoms are strong carbide-forming elements, while cemented carbide contains a large number of C atoms. Ti atoms have a very strong chemical affinity for C atoms, while Ag atoms are uniformly distributed.

[0043] As shown in Table 1, select Figure 9 In the brazed product in (a), EDS analysis of the interface between AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide was performed. Separately... Figure 9 Spot scanning was performed on points AG in (a), (b), and (c) to analyze the composition and phases. According to the atomic ratios in the table, the phases of A, B, C, D, E, F, and G are CuTi, Ag[s,s], Cu[s,s], TiC, Ni3Ti, Fe2Ti, and TiC, respectively. Figure 9 In (a), a relatively obvious black continuous region (A phase) exists at the interface of AK40 cemented carbide / Ag-Cu-Ti. Based on the atomic content ratios in Table 1, the phase at this location is CuTi. Figure 9 The large blank areas (phase B) in (a) are Ag solid solutions, while the light gray banded areas (phase C) are Cu solid solutions. Figure 9 As shown in (b) and (c), when the interfaces on both sides are magnified, black bands can be seen at the AK40 cemented carbide / Ag-Cu-Ti (D phase) and the Ag-Cu-Ti / AK40 cemented carbide (G phase). Combined with the atomic ratio in Table 1, it can be concluded that the phases formed by the D phase and the G phase are both TiC. The TiC phase is a hard and brittle phase that is prone to segregation, forming crack initiation and reducing plasticity and toughness. Figure 9 Based on the atomic ratios in Table 1, the E and F regions in (b) can be identified as Ni3Ti and Fe2Ti, respectively. Both Ni3Ti and Fe2Ti are brittle phases, and excessive or continuous distribution of them can significantly deteriorate the plasticity and toughness of the brazing seam, becoming crack initiation points and leading to low-stress brittle fracture of the joint.

[0044] In summary, combining Figure 9 As shown in (a)-(c) and Table 1, CuTi, TiC, Ni3Ti, and Fe2Ti are all distributed at the joint interface and are brittle phases, which will affect the mechanical properties of the joint. According to the interface embrittlement mechanism, continuous and coarse brittle phases will cause severe stress concentration, becoming the preferred path for crack initiation and propagation, and reducing the joint's plasticity and load-bearing capacity.

[0045] Figure 10 The image shows the microstructure of the brazed joints of AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide in the brazed products prepared in Examples 1-3. Figure 10 The brazed joint is visible to be dense, without cracks or other defects. With the increase of laser power, it is visible... Figure 10 With (a1)-(c1), the depth and width of the grooves on the AK40 cemented carbide surface increase accordingly, allowing the solder paste to bond more deeply with the cemented carbide. When... Figure 10 When the red-framed area in (a1)-(c1) is magnified, we obtain Figure 10 (a2)-(c2) were analyzed and EDS was performed on them. It can be seen that Cu atoms and Ti atoms are concentrated in the AK40 cemented carbide and / Ag-Cu-Ti.

[0046] Table 2 Figure 10 The elemental composition (at.%) of each point in the middle

[0047] As shown in Table 2, respectively for Figure 10Points A, B, and C in (a2)-(c2) were scanned and found to be CuTiIMC layers. An appropriate amount of CuTiIMC layer can effectively improve the metallurgical bonding ability between cemented carbide and Ag-Cu-Ti solder paste, and improve the interface strength and stability.

[0048] Figure 11 Line scan results of the brazed products prepared in Examples 1-3 and Comparative Example 1. Figure 11 As shown in (a) the line scan results at the joint, the thicknesses of the CuTiIMC layer were 1.5µm, 3.5µm, 2.5µm, and 1.5µm, respectively. The thickness of the CuTiIMC layer showed a trend of first increasing and then decreasing. The thickest CuTiIMC layer, 3.5µm, was reached when the laser power was 12.5W, approximately 1.3 times thicker than the CuTiIMC layer formed by the original surface brazing. However, an excessively thick CuTiIMC layer can easily lead to a decrease in joint strength, which explains why the joint strength did not improve significantly even at a laser power of 12.5W. The increase in the CuTiIMC layer thickness is due to the introduction of laser trenches, which to some extent enhanced atomic enrichment, leading to an increase in the reaction layer thickness.

[0049] Figure 12 This section describes the shear strength of AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide joints in brazed products prepared in Examples 1-6. The shear strength increases with increasing brazing temperature and holding time, then decreases. This indicates that the shear strength of the joint is significantly affected by the growth of the interfacial microstructure (see...). Figure 7 and Figure 8 This is because when the brazing temperature and holding time are relatively low, the TiC layer is relatively thin. As the brazing temperature and holding time increase, the Ag-Cu eutectic structure becomes richer, effectively hindering dislocation movement and significantly strengthening the joint. The shear strength reaches its maximum value of 189 MPa after holding at 865℃ for 10 minutes. Increasing the brazing temperature and holding time leads to a thicker brittle TiC layer, coarser morphology of the brittle Fe2Ti and Ni3Ti phases, and the growth of CuTi consumes excessive Cu atoms, resulting in an uneven distribution of the Ag-Cu eutectic structure and a decrease in the shear performance of the brazed joint.

[0050] Figure 13 This is the microhardness distribution at the joint of the brazed product prepared in Comparative Example 1. For AK40 cemented carbide / AK40 cemented carbide, the hardness of the weld and the matrix are approximately 152 HV and 1339 HV, respectively. Due to the lower strength and hardness of the silver-based solder paste, the hardness of the diffusion layer is lower than that of the cemented carbide matrix, while the CuTi phase is harder, around 400 HV, and from... Figure 7 and Figure 8 The microstructure of the interface between AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide confirms this. The CuTi phase exists in both the matrix and the weld, so the hardness of the weld exhibits a trend of first increasing, then decreasing, and then increasing again.

[0051] Figure 14 The shear strength of the brazed joints of the brazed products prepared in Examples 1-3 and Comparative Example 1. Figure 14 As shown, compared with the original cemented carbide joint in Comparative Example 1, the strength of the laser-modified joints in Examples 1-3 increased from 189 MPa to 219 MPa, an increase of 15.9%. This is because the laser formed a periodic structure and capillary effect on the cemented carbide surface, improving the wettability between the cemented carbide and the Ag-Cu-Ti brazing filler metal. Furthermore, the appropriate thickening of the CuTiIMC layer also improved the shear strength of the cemented carbide joint. However, since the CuTiIMC layer is brittle, an excessively thick CuTiIMC layer may actually lead to brittle fracture of the brazed joint. Therefore, even when the laser power was 12.5 W, the wettability of the Ag-Cu-Ti brazing filler metal on the cemented carbide surface was significantly improved, but due to the excessive thickness of the CuTiIMC layer in the cemented carbide brazed joint, the increase in shear strength was only 3.2%. Although the original cemented carbide brazed CuTiIMC layer and the CuTiIMC layer brazed with a laser power of 37.5W have similar thicknesses, their shear strength increases due to the increased wettability of the material surface and the increased contact area.

[0052] Table 3 Figure 15 and Figure 16 The elemental composition (at.%) of each point in the middle

[0053] Figure 15 Table 3 shows the fracture morphology of the brazed joints of the brazed products prepared in Comparative Examples 1-4. The elemental compositions of the AH points in the figures are Ag[s,s], Cu[s,s], Ag[s,s]+Cu[s,s], Ag[s,s]+Cu[s,s], TiC, TiC, TiC, and Cu[s,s], respectively, as shown in Table 3. When the temperature is 835℃, the fracture surface is mainly composed of Ag[s,s], Cu[s,s], and a gray-black microstructure (e.g., ...). Figure 15 (as shown in (a)), magnified Figure 15 The red-boxed area in (a) (e.g.) Figure 15 As shown in (e), perform a point scan on it (as shown in the diagram). Figure 15Point (e)E) indicates that the main phase on its surface is TiC phase, which is a brittle phase and prone to fracture. When the brazing temperature is 850℃, the microstructure of the fracture surface is mainly Ag-Cu eutectic and TiC phase (e.g., ...). Figure 15 Point D (c) and Figure 15 (f) point F). When the brazing temperature is 865℃, the fracture surface is mainly composed of Ag-Cu eutectic structure, indicating that the joint fractures mainly in the Ag-Cu eutectic alloy region, which is a ductile fracture, so the joint has good connection performance. When the brazing temperature is 880℃, the surface has a large number of gray areas, which can be observed through the analysis of... Figure 15 The red-boxed area in (d) (e.g.) Figure 15 As shown in (g), a surface scan is performed on its surface (e.g. Figure 15 As shown in (g1)-(g5), the fracture surface is mainly composed of Fe2Ti and Ni3Ti phases. Since TiC, Fe2Ti and Ni3Ti phases are all brittle phases, brittle fracture occurs here, resulting in a decrease in shear strength. When the brazing temperature increases, the thickness of the TiC layer increases, and the probability of fracture also increases.

[0054] Figure 16 Table 3 shows the fracture surface morphology of the joints of the brazed products prepared in Comparative Examples 1 and 5-6. As can be seen from Table 3, Figure 16 Points H and G in the figure represent TiC and Cu[s,s], respectively. When the holding time is 5 min, only a small amount of TiC is present on the fracture surface because the TiC layer is relatively thin at this time. Figure 16 Shear dimples can be seen in (a), further magnified. Figure 16 The red-boxed area in (a) (e.g.) Figure 16 The main component of the fracture surface (d) is Cu[s,s]. This is because the holding time is short, resulting in elemental segregation in the joint and uneven microstructure distribution, making it more prone to fracture under shear force. As the holding time increases, the TiC layer gradually thickens, and the fracture of the shear sample mainly occurs in the TiC layer, which is brittle fracture, leading to a decrease in shear strength.

[0055] The XRD patterns of the fracture surfaces of the brazed joints prepared in Comparative Examples 1-6 are shown below. Figure 17 As shown in the XRD pattern, Ag[s,s], WC, Cu[s,s], TiC, Cu[s,s], Fe2Ti and Ni3Ti can be seen on the fracture surface, which is consistent with the interface structure analysis of the fracture surface.

[0056] Figure 18 Microscopic morphology and EDS images of the fracture surface of the cemented carbide joint in the brazed products prepared in Example 2 and Comparative Example 1. Figure 18(a) is the shear fracture surface of the brazed product prepared in Comparative Example 1; Figure 18 (b) is the fracture surface of the laser-modified cemented carbide side in the brazed product of Example 2; Figure 18 (c) is the fracture surface of the non-laser modified cemented carbide side in the brazed product of Example 2; Figure 18 (d)-(h) is Figure 18 EDS plot (b). The EDS element distribution on the fracture surface shows that both W and solder paste elements occupy a large area within the fracture region, indicating that the fracture path simultaneously passes through the cemented carbide matrix and the brazing layer, rather than simply separating along the interface. Combining the shear test results and fracture morphology characteristics, it can be further determined that: if the joint failure occurs at the interface or brazing seam, the fracture surface will be dominated by elements from the solder paste, with W elements distributed less and discontinuously; however, in this invention, W elements are distributed continuously over a large area, and elements from the solder paste are also present, indicating that the crack penetrated the cemented carbide surface layer during propagation and extended within the cemented carbide, ultimately causing the fracture area to be mainly concentrated within the cemented carbide matrix, rather than at the interface or brazing seam.

[0057] Table 4 Figure 18 The elemental composition (at.%) of each point in the middle

[0058] As shown in Table 4, for Figure 18 Spot scanning of the AG points revealed that the main phase on the shear fracture surface of the original cemented carbide was an Ag-Cu eutectic structure. The phase interface between the α and β phases effectively hindered dislocation movement, producing a significant strengthening effect. Compared to a single solid solution, the eutectic structure typically provides higher strength, hardness, and a certain degree of plasticity simultaneously, giving the joint better impact and vibration fatigue resistance. Therefore, the formation of the Ag-Cu eutectic structure effectively improves the joint strength. On the fracture surfaces of both the laser-modified and non-laser-modified cemented carbide sides, in addition to the Ag-Cu eutectic region, a WC phase was also observed. Figure 10 (c) shows cracks on the fracture surface of the non-laser-modified side, indicating good interfacial bonding and contributing to the increased joint strength. Based on the above analysis, the fracture paths of brazed joints under different power levels can be obtained, such as... Figure 19 As shown.

[0059] Figure 20 The figures show the microstructure of the fracture surface of the brazed products prepared in Examples 1-3. As can be seen from the figures, with the increase of laser power, the grooves on the surface of the cemented carbide become more and more obvious, and the WC area on the fracture surface also shows a trend of first increasing and then decreasing. When shear fracture occurs inside the matrix material, it can show an increase in shear strength, which is consistent with the results of the shear test.

[0060] like Figure 21 As shown, for Figure 20 (a1) and Figure 20 EDS analysis was performed on (c1) and compared with... Figure 18 In comparison, it can be found that as the laser power increases, the W element on the fracture surface shows a trend of first increasing and then decreasing, which confirms the above-mentioned trend that the WC area also shows a trend of first increasing and then decreasing.

[0061] Table 5 Figure 20 The elemental composition (at.%) of each point in the middle

[0062] right Figure 20 The AF points in the data were scanned, and the results are shown in Table 5. Figure 20 In (a1), when the power is 12.5W, a black object with silvery-white material is found on the fracture surface of the laser-modified cemented carbide. Spot scanning reveals that the silvery-white material is Cu[s,s] and Cu2Ti, while the black object is composed of WC, proving that part of the shear fracture occurs in the matrix material. Spot scanning of the fracture surface of the non-laser-modified cemented carbide at a laser power of 12.5W reveals that the main phase is CuTi, and the presence of brittle phases leads to a decrease in shear strength. Figure 11 (b) shows that the CuTiIMC layer is thickest when the laser power is 12.5W, so it is possible that shear fracture occurs in the CuTiIMC layer. This result is consistent with the above. Figure 14 The analysis results are consistent with those of the shear test. When the laser power is 37.5W, the fracture surface is relatively smooth. Spot scanning of the fracture surfaces on both the laser-modified and non-laser-modified cemented carbide sides revealed that the main surface phases were Ag-Cu eutectic structures. Figure 21 The EDS images show that Ag and Cu elements occupy most of the surface area of ​​the fracture surface under different laser powers, which corresponds to the results of spot scanning.

[0063] The formation mechanism of laser-modified AK40 cemented carbide brazed joints and the formation mechanism of Ag-Cu-Ti brazed cemented carbide joints are as follows: Figure 22-23 As shown.

[0064] like Figure 23 As shown in (a), (b), (c), and (d), based on the analysis of the interface microstructure, the composition of AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide is AK40 cemented carbide / TiC+CuTi / Ag[s,s]+Cu[s,s]+Ag-Cu eutectic+Fe2Ti+Ni3Ti / CuTi+TiC / AK40 cemented carbide. The formation on the joint involves four processes: as... Figure 23As shown in (a), the solder comes into physical contact with the base material, the solder melts, and as the temperature rises, atoms in the solder and AK40 cemented carbide diffuse; as Figure 23 As shown in (b), active Ti atoms accumulate on the joint side of the AK40 alloy. Some Cu atoms also accumulate on the AK40 cemented carbide side, surrounding the Ti atoms. Fe and Ni atoms in the AK40 cemented carbide also accumulate at the interface; as shown in (b). Figure 23 As shown in (c), a small amount of Ti atoms react with C atoms in the AK40 cemented carbide to form a continuous TiC layer. Simultaneously, Ti atoms and Cu atoms at the junction react to form CuTi, while the remaining Ti atoms react with Fe and Ni atoms respectively to form Fe2Ti and Ni3Ti. Finally, Ag[s,s] and Cu[s,s] precipitate; as shown... Figure 23 As shown in (d), as the brazing temperature and holding time gradually increase, the reaction layer gradually thickens, the intermediate layer also tends to stabilize, and finally a weld is formed.

[0065] like Figure 23 As shown in (e), a laser is used to create uniform V-shaped grooves on the surface of a cemented carbide, according to... Figure 22 Samples of AK40 cemented carbide / Ag-Cu-Ti / AK40 cemented carbide were assembled. During the brazing heating process, after the temperature rose to the melting point of the solder paste, the Ag-Cu-T solder paste melted, and the molten solder filled the grooves on the surface of the cemented carbide under the action of capillary effect. Cu and Ti atoms in the solder diffused to the surface of the cemented carbide. As the temperature increased, Cu and Ti atoms reacted with the surface of the cemented carbide, and a CuTi IMC layer was generated in the groove and at the interface. The thickness of the CuTi IMC layer was significantly different when comparing the laser power of 12.5W and the laser power of 12.5W. The IMC layer was thicker when the laser power was 12.5W. During the heat preservation stage, the interface reaction continued, and the thickness of the IMC layer gradually stabilized. Finally, a composite phase structure of "CuTi IMC layer + Ag[s,s] + Cu[s,s] + Ag-Cu eutectic" was formed on the laser-modified side interface, and the brazed joint achieved a tight bond.

[0066] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for alloy brazing joining based on laser modification, characterized in that, Includes the following steps: Step (1): Laser-modified cemented carbide is used to process groove structures to obtain laser-modified cemented carbide. The conditions for laser modification treatment are as follows: laser power of 1-50W, spacing of 0.005-0.5mm, speed of 50-150mm / s, frequency of 1-50KHz, pulse width of 2-500ns, and wavelength of 248-1065nm; the width of the trench structure is 32.8-65.9μm, and the depth is 42.3-107.6μm. Step (2): The cemented carbide and the laser-modified cemented carbide are brazed together using Ag-Cu-Ti solder paste to obtain the brazed product.

2. A method of laser-modification based alloy brazing joining according to claim 1, characterized in that In step (1), the conditions for laser modification are: laser power of 25W, spacing of 0.5mm, speed of 80mm / s, frequency of 20KHz, pulse width of 100ns, and wavelength of 1065nm.

3. A method of laser-modification based alloy brazing joining according to claim 1, characterized in that, In step (1), the width of the trench structure is 59.4 μm and the depth is 74.1 μm.

4. The method of laser modified alloy brazing connection according to claim 1, characterized in that, In step (2), the brazing operation includes: applying solder paste to the modified surface of the laser-modified cemented carbide, placing another cemented carbide on the solder paste, brazing, and cooling with the furnace after brazing.

5. The method of laser modified alloy brazing connection according to claim 1, characterized in that, In step (2), the thickness of the Ag-Cu-Ti solder paste is 0.06-0.1 mm.

6. The laser-modified alloy brazing connection method according to claim 5, characterized in that, In step (2), the mass percentage of each component in the Ag-Cu-Ti solder paste is: 23-50% Cu, 2-5% Ti, and the balance is Ag.

7. The laser-modified alloy brazing joining method according to claim 1, characterized in that, The brazing condition in step (2) is: holding for 5-13 min at 835-880℃, vacuum degree in the furnace is 7×10 -4 Pa, heating rate is 1-20℃ / min, and cooling rate is 1-20℃ / min. - 3 Pa, heating rate is 1-20℃ / min, and cooling rate is 1-20℃ / min.

8. A brazed product prepared by the laser-modified alloy brazing joining method as described in any one of claims 1-7.

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