Aluminum / tungsten ultrasonic-assisted brazing method based on in-situ synthesis of low-temperature filler metal and joint

Abstract

The application discloses an aluminum / tungsten ultrasonic-assisted brazing method based on in-situ synthesis of low-temperature filler metal, and comprises the following steps: providing an aluminum alloy, a tungsten alloy and a filler metal layer, wherein the material of the filler metal layer is tin or zinc; stacking the aluminum alloy, the filler metal layer and the tungsten alloy in sequence to obtain an assembly; heating the assembly to a brazing temperature and performing ultrasonic-assisted brazing to obtain an aluminum / tungsten ultrasonic-assisted brazing joint. The method realizes low-temperature metallurgical combination of pure tin filler metal or pure zinc filler metal and the tungsten alloy by adopting the ultrasonic-assisted brazing process, reduces the brazing temperature of the tungsten alloy, and makes the brazing easier to perform. The application further provides a joint prepared by the method.

Description

Technical Field

[0001] This invention relates to the field of brazing technology, specifically to an ultrasonic-assisted brazing method and joint for aluminum / tungsten based on in-situ synthesis of low-temperature brazing filler metal. Background Technology

[0002] Nuclear energy, as an important clean energy source, is widely used in various fields such as military, medical, and industrial applications. Research shows that electronic components exposed to radiation for extended periods are prone to a series of radiation damage effects, such as total ionizing dose, single-event effects, and displacement damage, leading to component malfunctions. To ensure the long-term, normal operation of electronic components in nuclear radiation environments, appropriate shielding and protection measures are necessary.

[0003] Traditional nuclear radiation shielding materials typically use lead / steel double-layer metal shielding. However, lead and lead alloys are listed in my country's "Priority Controlled Chemicals List" and "List of Hazardous and Toxic Water Pollutants" due to their toxicity, harm to humans and the environment, and tendency to produce bremsstrahlung in nuclear radiation environments. Therefore, the application of lead-steel double-layer metal shielding materials is limited. Research has found that tungsten alloys possess excellent radiation resistance, are non-toxic, and do not produce bremsstrahlung, making them a viable alternative to lead alloys as radiation shielding metal materials. The primary function of the cladding material is to prevent the escape of fission products, requiring a small thermal neutron absorption cross-section. Currently, commonly used cladding materials include steel and aluminum alloys. Compared to steel, aluminum alloys offer advantages such as lower density, better plasticity and thermal conductivity, and a lower thermal neutron absorption cross-section (0.23 target). Therefore, aluminum / tungsten double-layer metal shielding materials, composed of aluminum alloys and tungsten alloys, hold promise as a potential replacement for lead / steel structures as a new generation of nuclear radiation shielding materials.

[0004] Tungsten (W) and aluminum (Al) have significantly different physical and chemical properties. Tungsten has a melting point of 3380℃, while aluminum has a melting point of 660℃ and a boiling point of 2327℃. When an aluminum alloy reaches its boiling point, a tungsten alloy has not yet melted. Furthermore, their coefficients of thermal expansion differ greatly; tungsten's coefficient of thermal expansion is 4.5 × 10⁻⁶. -6 C -1 The coefficient of thermal expansion of aluminum is 23.6 × 10⁻⁶. -6 C -1 The two materials have nearly four times different coefficients of thermal expansion, which may lead to large residual stress during the cooling process after welding, resulting in low joint strength. Therefore, there is an urgent need for a suitable welding method to achieve a reliable connection between the two materials. Summary of the Invention

[0005] To address this, the present invention provides an ultrasonic-assisted brazing method and joint for aluminum / tungsten based on in-situ synthesis of low-temperature brazing filler metal. The method utilizes an ultrasonically induced extreme non-equilibrium environment to promote the rapid dissolution of aluminum alloy into molten tin or zinc, generating tin-aluminum alloy or zinc-aluminum alloy brazing filler metal in situ. The localized high temperature and pressure generated by ultrasound in the liquid brazing filler metal stimulate the solid-liquid interface, promoting the metallurgical bonding of aluminum and tungsten elements in the liquid brazing filler metal, thus achieving the connection between the aluminum alloy and the tungsten alloy and solving the aforementioned problems.

[0006] This invention proposes an ultrasonic-assisted brazing method for aluminum / tungsten based on in-situ synthesized low-temperature brazing filler metal, comprising: providing an aluminum alloy, a tungsten alloy, and a brazing filler metal layer, wherein the brazing filler metal layer is made of tin or zinc; sequentially stacking the aluminum alloy, the brazing filler metal layer, and the tungsten alloy to obtain an assembly; heating the assembly to a brazing temperature and performing ultrasonic-assisted brazing to obtain an aluminum / tungsten ultrasonic-assisted brazed joint.

[0007] The above method employs ultrasonic-assisted brazing, utilizing the cavitation and acoustic flow effects of ultrasound in liquid tin to generate localized high temperatures and pressures. This excites the solid-liquid interface, causing the aluminum alloy to dissolve into the liquid tin or zinc, forming an in-situ tin-aluminum or zinc-aluminum alloy. This in-situ generation of tin-aluminum or zinc-aluminum alloy brazing filler metal allows aluminum to form compounds with tungsten at low temperatures, achieving low-temperature metallurgical bonding between pure tin or pure zinc brazing filler metal and the tungsten alloy. This lowers the brazing temperature of the tungsten alloy, making brazing easier. Furthermore, the application of ultrasonic vibration removes the oxide film from the aluminum alloy surface. No flux is required during the brazing process, resulting in energy saving, environmental protection, low cost, simple operation, and energy reduction and emission reduction.

[0008] In some embodiments, before providing the aluminum alloy, tungsten alloy, and solder layer, the method further includes: selecting the aluminum alloy and the tungsten alloy of a preset thickness; machining the surfaces of the aluminum alloy and the tungsten alloy to a mirror finish; and cleaning the aluminum alloy and the tungsten alloy to remove impurities from their surfaces, thereby obtaining the pretreated aluminum alloy and the tungsten alloy.

[0009] In some embodiments, the thickness of the aluminum alloy ranges from 3mm to 7mm, and the thickness of the tungsten alloy ranges from 3mm to 7mm.

[0010] In some embodiments, the thickness of the solder layer ranges from 50 μm to 150 μm.

[0011] In some embodiments, the method for ultrasonically assisted brazing of the assembly includes: placing the assembly in the heating device; after the temperature in the heating device reaches the brazing temperature, applying a preset pressure to the assembly to compress it; and subjecting the assembly to ultrasonic vibration to obtain an aluminum / tungsten ultrasonically assisted brazing joint.

[0012] In some embodiments, when the solder layer is made of tin, the brazing temperature ranges from 240°C to 260°C; when the solder layer is made of zinc, the brazing temperature ranges from 400°C to 420°C.

[0013] In some embodiments, applying a preset pressure to the assembly includes: continuously applying the preset pressure to the assembly using an ultrasonic tool head, wherein the vibration direction of the ultrasonic tool head is perpendicular to the assembly, and the ultrasonic vibration power of the ultrasonic tool head is 30W-300W, and the ultrasonic frequency is 20kHz.

[0014] In some embodiments, the time for applying the preset pressure is 2s-10s.

[0015] In some embodiments, the preset pressure ranges from 0.1 MPa to 0.5 MPa.

[0016] The present invention also proposes a connector prepared using the above-described method.

[0017] The aforementioned connectors have high connection strength and are suitable for use as radiation shielding metal materials. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the ultrasonic-assisted brazing process for aluminum alloy and tungsten alloy proposed in this invention.

[0019] Figure 2 This is a microstructure diagram of the ultrasonic-assisted brazed joint in Embodiment 1 of this application.

[0020] Figure 3 This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 2 of this application.

[0021] Figure 4 This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 3 of this application.

[0022] Figure 5 This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 4 of this application.

[0023] Figure 6 This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 5 of this application.

[0024] Figure 7 This is a microstructure diagram of the ultrasonic-assisted brazed joint in Embodiment 6 of this application.

[0025] Figure 8 This is a microstructure diagram of the ultrasonic-assisted brazed joint in Embodiment 7 of this application.

[0026] Figure 9This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 8 of this application.

[0027] Figure 10 This is a microstructure diagram of the ultrasonic-assisted brazing joint in Embodiment 9 of this application.

[0028] Explanation of main component symbols

[0029] Tungsten alloy 1 aluminum alloy 2 solder layer 3 solid solution 4 Ultrasonic tool head 5 Heating device 6 Detailed Implementation

[0030] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0031] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0035] Please see Figure 1 The present invention also proposes a connector, which is formed by brazing aluminum alloy 2, tungsten alloy 1 and a brazing filler layer 3, wherein the brazing filler layer 3 is disposed between aluminum alloy 2 and tungsten alloy 1. This connector has high connection strength and can be used as a radiation shielding metal material.

[0036] This invention proposes an ultrasonic-assisted brazing method for aluminum / tungsten based on in-situ synthesis of low-temperature brazing filler metal, comprising:

[0037] S10 provides aluminum alloy 2, tungsten alloy 1 and solder layer 3, the solder layer 3 being made of tin or zinc.

[0038] S20, aluminum alloy 2, brazing layer 3 and tungsten alloy 1 are stacked in sequence to obtain an assembly with a "sandwich" structure.

[0039] S30, the assembly is heated to the brazing temperature and ultrasonically assisted brazing is performed to obtain an aluminum / tungsten ultrasonically assisted brazed joint. When the material of the brazing filler layer 3 is tin, the brazing temperature range is 240℃-260℃, and the preferred brazing temperature is 250℃. When the material of the brazing filler layer 3 is zinc, the brazing temperature range is 400℃-420℃, and the preferred brazing temperature is 410℃.

[0040] In some embodiments, the method of ultrasonically assisted brazing of the assembly includes:

[0041] S31, place the assembly into the heating device 6.

[0042] S32, after the temperature inside the heating device 6 reaches the brazing temperature, a preset pressure is applied to the assembly to tighten it.

[0043] In this process, an ultrasonic tool head 5 continuously applies a preset pressure to the assembly. The vibration direction of the ultrasonic tool head 5 is perpendicular to the assembly. The power of the ultrasonic vibration of the ultrasonic tool head 5 is 30W-300W, and the ultrasonic frequency is 20kHz. Preferably, the power range of the ultrasonic vibration is 100W-180W.

[0044] The end of the ultrasonic tool head 5 is a circle with a diameter of 10mm.

[0045] The time for applying the preset pressure is 2s-10s.

[0046] The preset pressure ranges from 0.1 MPa to 0.5 MPa. Preferably, the preset pressure is 0.3 MPa.

[0047] S33, ultrasonic vibration is applied to the assembly to obtain an aluminum / tungsten ultrasonic-assisted brazing joint.

[0048] The above method employs ultrasonic-assisted brazing, utilizing the cavitation and acoustic flow effects of ultrasound in liquid tin to generate localized high temperatures and pressures. This excites the solid-liquid interface, causing the aluminum alloy to dissolve into the liquid tin or zinc, forming an in-situ tin-aluminum or zinc-aluminum alloy. This in-situ formation of the tin-aluminum or zinc-aluminum alloy brazing filler metal allows aluminum to form compounds with tungsten at temperatures of 240℃-260℃ or 400℃-420℃, achieving low-temperature metallurgical bonding between pure tin or pure zinc brazing filler metal and the tungsten alloy. This reduces the brazing temperature of the tungsten alloy, making brazing easier. Furthermore, the application of ultrasonic vibration removes the oxide film from the aluminum alloy surface. No flux is required during the brazing process, resulting in energy saving, environmental friendliness, low cost, simple operation, and energy reduction and emission reduction.

[0049] In some embodiments, before providing the aluminum alloy 2, tungsten alloy 1, and solder layer 3, the method further includes:

[0050] S01, Select aluminum alloy 2 and tungsten alloy 1 with preset thicknesses;

[0051] The thickness of aluminum alloy 2 ranges from 3mm to 7mm. Preferably, the thickness of aluminum alloy 2 is 5mm.

[0052] The thickness of tungsten alloy 1 ranges from 3mm to 7mm. Preferably, the thickness of aluminum alloy 2 is 5mm.

[0053] The thickness of the solder layer 3 ranges from 50 μm to 150 μm. The preferred thicknesses of the solder layer 3 are 50 μm, 100 μm, and 150 μm.

[0054] S02, the surfaces of aluminum alloy 2 and tungsten alloy 1 are machined to a mirror finish.

[0055] The process involves using sandpaper or a sanding disc to grind aluminum alloy 2 and tungsten alloy 1, and then using diamond polishing compound to mechanically polish aluminum alloy 2 and tungsten alloy 1 until the surfaces of aluminum alloy 2 and tungsten alloy 1 achieve a mirror finish.

[0056] S03, clean aluminum alloy 2 and tungsten alloy 1 to remove impurities from their surfaces, thereby obtaining pretreated aluminum alloy 2 and tungsten alloy 1.

[0057] In this process, aluminum alloy 2 and tungsten alloy 1 are placed in acetone and ultrasonically cleaned at room temperature for 15 minutes to remove impurities from their surfaces. After removal, they are dried with cold air for later use, resulting in pretreated aluminum alloy 2 and tungsten alloy 1.

[0058] The technical solution of the present invention is not limited to the specific embodiments exemplified below, but also includes any combination of the specific embodiments.

[0059] Example 1

[0060] Embodiment 1 of this invention proposes an ultrasonic-assisted brazing method for aluminum / tungsten based on in-situ synthesis of low-temperature brazing filler metal, comprising the following steps:

[0061] A 5mm thick 6061 aluminum alloy and a 5mm thick W90NiFe tungsten alloy were provided as the base materials to be welded. They were cut into 9mm×9mm sizes and polished with 800#, 1200#, 2000# and 3000# sandpaper or sanding discs in sequence. Then, they were polished with 0.5μm and 0.25μm diamond polishing and mechanical polishing in sequence until the surface of the base materials to be welded was mirror-like. The base materials to be welded were then placed in acetone and ultrasonically cleaned at room temperature for 15 minutes to remove impurities from the surface of the base materials to be welded. After removal, they were dried with cold air and ready for use to obtain pretreated aluminum alloy 2 and tungsten alloy 1.

[0062] Aluminum alloy 2, solder layer 3, and tungsten alloy 1 are sequentially stacked to obtain an assembly. The solder layer 3 is made of tin and has a thickness of 100 μm. It is understood that in other embodiments, the thickness of solder layer 3 is 50 μm. It is understood that in other embodiments, the thickness of solder layer 3 is 150 μm, but is not limited to this. It is understood that in other embodiments, the solder layer 3 is made of zinc.

[0063] The brazing temperature is set to 250℃. After the heating device 6 reaches the preset temperature, the assembly is placed on the heating device 6, with the tungsten alloy 1 at the top. The upper surface of the tungsten alloy 1 is directly acted on through the end of the ultrasonic tool head 5. A pressure of 0.3MPa is applied to the assembly to ensure that the assembly is always in a compressed state. The ultrasonic tool head 5 is started to apply continuous ultrasonic vibration to the assembly. The ultrasonic power is 100W, the ultrasonic frequency is 20kHz, and the ultrasonic action time is 8s. The ultrasonic vibration is transmitted through the tungsten alloy 1 to the molten pure tin, indirectly applying ultrasonic vibration to the molten pure tin. Then the ultrasonic device and the heating device 6 are turned off, and the assembly is cooled to room temperature. After the brazing filler solidifies, the pressure is removed to obtain a W90NiFe / Sn / Al ultrasonic-assisted brazed joint.

[0064] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 2 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 8.2 MPa.

[0065] Example 2

[0066] The method in this embodiment is largely the same as that in Example 1, except that the ultrasonic power of the ultrasonic tool head 5 is 100W.

[0067] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 3 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 14.1 MPa.

[0068] Example 3

[0069] The method in this embodiment is largely the same as that in Example 1, except that the ultrasonic power of the ultrasonic tool head 5 is 140W.

[0070] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 4 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 13.6 MPa.

[0071] Example 4

[0072] The method in this embodiment is largely the same as that in Example 1, except that the ultrasonic power of the ultrasonic tool head 5 is 160W.

[0073] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 5 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 11.9 MPa.

[0074] Example 5

[0075] The method in this embodiment is largely the same as that in Example 1, except that the ultrasonic power of the ultrasonic tool head 5 is 180W.

[0076] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 6 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 7.1 MPa.

[0077] Depend on Figures 2 to 6 It can be seen that the weld width of the ultrasonic-assisted brazed joints in Examples 1-5 first increases and then decreases with increasing ultrasonic power; the weld width in Example 4 reaches its maximum value of 19.13 μm. The weld in Example 1 contains only pure tin, and no Al dissolution occurs. The welds in Examples 2-5 contain Al(Sn). From the strength of the ultrasonic-assisted brazed joints in Examples 1-5, it can be seen that the strength of the ultrasonic-assisted brazed joint first increases and then decreases with increasing ultrasonic power, reaching its maximum strength when the ultrasonic power is 120W. Therefore, in the ultrasonic-assisted brazing process, the ultrasonic power is preferably 120W.

[0078] Example 6

[0079] The method in this embodiment is largely the same as that in Example 2, except that the ultrasonic treatment time is 2 seconds.

[0080] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 7 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 7.0 MPa.

[0081] Example 7

[0082] The method in this implementation is largely the same as that in Example 1, except that the ultrasonic treatment time is 4 seconds.

[0083] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 8 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 12.1 MPa.

[0084] Example 8

[0085] The method in this implementation is largely the same as that in Example 1, except that the ultrasonic treatment time is 6 seconds.

[0086] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 9 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 21.2 MPa.

[0087] Example 9

[0088] The method in this implementation is largely the same as that in Example 1, except that the ultrasonic treatment time is 10 seconds.

[0089] Microscopic observation of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint was performed using scanning electron microscopy (SEM), and the results were as follows: Figure 10 The microstructure of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint is shown. The mechanical properties of the W90NiFe / Sn / Al ultrasonic-assisted brazed joint were tested, and the joint strength was 7.3 MPa.

[0090] Please see Figure 3 , Figures 7-10 It can be seen that as the ultrasonic time increases, the weld width narrows, the amount of Al matrix dissolved into Sn gradually increases, and the solid solution 4 formed by Al(Sn) appears and extends to the W90NiFe / Sn interface. As can be seen from the ultrasonic-assisted brazing joint strength of Examples 2 and 6-9, the strength of the ultrasonic-assisted brazing joint first increases and then decreases with the increase of ultrasonic time. When the ultrasonic time is 6s, the strength of the ultrasonic-assisted brazing joint is the greatest. Therefore, in the ultrasonic-assisted brazing process, the ultrasonic time is preferably 6s.

[0091] In summary, the optimal conditions for ultrasonic-assisted brazing of aluminum alloys and tungsten alloys are: ultrasonic power of 120W and ultrasonic time of 6s; the microstructure of the ultrasonic-assisted brazed joint under optimal conditions is shown in the figure below. Figure 9 As shown, the strength of the ultrasonic-assisted brazed joint reaches 21.2 MPa.

[0092] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application 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 this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. An ultrasonic-assisted brazing method of aluminum / tungsten based on in-situ synthesis of low-temperature filler metal, characterized by, The method comprises the following steps: providing an aluminum alloy, a tungsten alloy and a filler layer, the filler layer being made of tin or zinc; stacking the aluminum alloy, the filler layer and the tungsten alloy in sequence to obtain an assembly; heating the assembly to a brazing temperature and performing ultrasonic-assisted brazing to obtain an aluminum / tungsten ultrasonic-assisted brazing joint, the rapid dissolution of the aluminum alloy into the molten tin or zinc is promoted by the extreme non-equilibrium environment induced by ultrasonic, tin-aluminum alloy filler or zinc-aluminum alloy filler is generated in situ, the local high temperature and high pressure generated in the liquid filler by ultrasonic excite the solid-liquid interface, promote the metallurgical bonding of aluminum and tungsten in the liquid filler, and realize the connection of the aluminum alloy and the tungsten alloy, when the filler layer is made of tin, the brazing temperature ranges from 240°C to 260°C; when the filler layer is made of zinc, the brazing temperature ranges from 400°C to 420°C; the method for performing ultrasonic-assisted brazing on the assembly comprises the following steps: placing the assembly in a heating device; after the temperature in the heating device reaches the brazing temperature, applying a preset pressure to the assembly to compress the assembly; performing ultrasonic vibration on the assembly to obtain an aluminum / tungsten ultrasonic-assisted brazing joint; the step of applying the preset pressure to the assembly comprises the following steps: continuously applying the preset pressure to the assembly by using an ultrasonic tool head, the vibration direction of the ultrasonic tool head is perpendicular to the assembly, the power of the ultrasonic vibration of the ultrasonic tool head is 30W-300W, and the ultrasonic frequency is 20 kHz.

2. The in-situ synthesis of low temperature braze based aluminum / tungsten ultrasonic assisted brazing method according to claim 1, characterized in that, Before the step of providing the aluminum alloy, the tungsten alloy and the filler layer, the method further comprises the following steps: selecting the aluminum alloy and the tungsten alloy with a preset thickness; processing the surfaces of the aluminum alloy and the tungsten alloy to mirror surfaces; cleaning the aluminum alloy and the tungsten alloy to remove impurities on the surfaces of the aluminum alloy and the tungsten alloy, thereby obtaining pretreated aluminum alloy and tungsten alloy.

3. The in-situ synthesis low-temperature filler metal based aluminum / tungsten ultrasonic-assisted brazing method according to claim 1 or 2, characterized in that, The thickness of the aluminum alloy ranges from 3mm to 7mm, and the thickness of the tungsten alloy ranges from 3mm to 7mm.

4. The in-situ synthesis of low temperature braze based aluminum / tungsten ultrasonic assisted brazing method according to claim 1, characterized in that, The thickness of the filler layer ranges from 50μm to 150μm.

5. The in-situ synthesis of low temperature braze based aluminum / tungsten ultrasonic assisted brazing method according to claim 1, characterized in that, The time for applying the preset pressure ranges from 2s to 10s.

6. The in-situ synthesis of low temperature braze based aluminum / tungsten ultrasonic assisted brazing method according to claim 5, characterized in that, The range of the preset pressure is 0.1MPa-0.5 MPa.

7. A joint, characterized by The method is prepared by any one of claims 1-6.

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