Pre-embedded brazing flux aluminum alloy composite material and preparation method thereof

Abstract

The present application relates to the technical field of aluminum alloy brazing, and particularly relates to a pre-embedded brazing flux aluminum alloy composite material and a preparation method thereof. The provided preparation method comprises the following steps: filling mixed powder into a box body provided with an open end at one end, arranging a top plate at the open end to obtain a package; wherein the top plate comprises an aluminum-silicon alloy; the box body comprises an aluminum alloy; the mixed powder comprises aluminum alloy powder and brazing flux powder; vacuum hot-pressing sintering the package to obtain a first composite blank; stacking the first composite blank away from the top plate with an aluminum alloy ingot to form a second composite blank; wherein the material of the aluminum alloy ingot is the same as that of the box body; hot-rolling, cold-rolling and annealing the second composite blank to obtain the pre-embedded brazing flux aluminum alloy composite material. The preparation method of the present application improves the interface bonding strength and effectively avoids rolling cracking under high brazing flux content.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy brazing technology, and in particular to an aluminum alloy composite material with pre-embedded brazing flux and its preparation method. Background Technology

[0002] In the manufacturing of aluminum alloy heat exchangers (such as condensers, evaporators, and oil coolers), to address the problems of cumbersome processes, poor flux accessibility, and residual corrosion caused by the need for additional flux application in brazing, researchers have proposed a "pre-embedded flux" solution. This involves pre-compositing the flux into the brazing filler layer of the aluminum alloy sheet, allowing the material to autonomously break down the film and fill during brazing heating, thus eliminating the need for external flux application. Existing technologies often employ a combined process of powder metallurgy and hot rolling. For example, potassium fluoroaluminate flux powder is mechanically mixed with aluminum-silicon alloy powder and first filled into a temporary sheath made of pure aluminum or aluminum alloy. This mixture is then densified using hot isostatic pressing to obtain a powder metallurgy ingot. Subsequently, the temporary sheath is completely removed by machining, and the exposed powder metallurgy ingot is then stacked with an aluminum alloy ingot and hot-rolled to finally produce a composite sheet of the required thickness. This approach provides a feasible exploratory path for the preparation of pre-embedded flux composite materials.

[0003] However, the pre-embedded flux layer obtained through powder metallurgy differs fundamentally from the aluminum alloy core material formed by casting in terms of composition, microstructure, and high-temperature rheological stress. Their ability to coordinate deformation during subsequent high-reduction hot rolling is significantly insufficient, easily leading to defects such as poor bonding, microcracks, and even macroscopic cracking at the composite interface. These defects are particularly pronounced when rolling to thinner gauges or requiring higher flux content. Furthermore, the mechanical milling process introduced to remove the temporary sheath not only increases the number of process steps and material waste but also negatively impacts production efficiency and cost control due to the complexity of clamping and machining.

[0004] Therefore, how to obtain a pre-embedded flux aluminum alloy composite material with strong interfacial bonding and both high flux content and good processing performance has become an important research topic. Summary of the Invention

[0005] In view of this, the present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides a pre-embedded flux aluminum alloy composite material and its preparation method, which can effectively improve the interfacial bonding strength and effectively avoid rolling cracking under high flux content.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a method for preparing a pre-embedded flux aluminum alloy composite material is provided, comprising the following steps: The mixed powder is filled into a box with an open end, and a top plate is placed at the open end to obtain a casing; wherein, the top plate comprises an aluminum-silicon alloy; the box comprises an aluminum alloy; and the mixed powder comprises aluminum alloy powder and flux powder; The casing is subjected to vacuum hot pressing sintering to obtain the first composite blank; The first composite blank is stacked with an aluminum alloy ingot on the side away from the top plate to form a second composite blank; wherein the material of the aluminum alloy ingot is the same as the material of the box body; The second composite billet is hot-rolled, cold-rolled, and annealed to obtain the pre-embedded flux aluminum alloy composite material.

[0007] In some embodiments, the weight ratio of the aluminum alloy powder to the flux powder in the mixed powder is (9~18):(82~91).

[0008] In some embodiments, the aluminum alloy powder includes Al-Si alloy powder.

[0009] In some embodiments, the flux powder is a KAlF4-K2AlF5 mixed powder, wherein the weight ratio of KAlF4 to K2AlF5 is (70-80):(20-30).

[0010] In some embodiments, the housing includes a bottom plate and side plates, the bottom plate being made of 3003 aluminum alloy and the side plates being made of 3003 aluminum alloy.

[0011] In some embodiments, the aluminum-silicon alloy includes any one of alloy 4045, alloy 4047, or aluminum alloy 4343.

[0012] In some embodiments, the thickness of the top plate is 5mm to 20mm.

[0013] In some embodiments, the Al-Si alloy powder contains 7% to 12.5% ​​silicon by mass.

[0014] In some of these embodiments, the median particle size D of the Al-Si alloy powder 50 The range is 20μm to 60μm.

[0015] In some of these embodiments, the oxygen content of the Al-Si alloy powder is less than 300 ppm.

[0016] In some of these embodiments, the median particle size D of the flux powder 50 The range is 10μm to 50μm.

[0017] In some embodiments, the silicon content in the aluminum-silicon alloy is 6.8% to 13% by mass.

[0018] In some embodiments, the thickness of the side plate is 1mm to 3mm.

[0019] In some embodiments, the thickness of the base plate is 1mm to 3mm.

[0020] In some embodiments, the mixed powder is mixed using a V-type powder mixer to mix the aluminum alloy powder and the flux powder for a time of 2h to 6h and a rotation speed of 2r / min to 6r / min.

[0021] In some embodiments, prior to vacuum hot pressing sintering, the process further includes: The box body and the top plate are welded and sealed. A through hole is provided on the top plate. A vacuum is drawn into the sleeve through the through hole. When the vacuum degree inside the sleeve is less than the preset vacuum degree, the through hole is sealed. The preset vacuum degree is 1×10⁻⁶. -2 Pa.

[0022] In some embodiments, the vacuum hot pressing sintering includes: The cladding is placed in a vacuum hot-pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 1×10⁻⁶. -2 When Pa, the temperature is increased to the sintering temperature; and pressure is applied to the top and bottom of the casing. The vacuum hot pressing sintering also satisfies at least one of the following characteristics (1) to (3): (1) The sintering temperature is 450℃~550℃; (2) The applied pressure is 30MPa~80MPa, and the holding time is 2h~5h; (3) The heating rate is 8~15℃ / min.

[0023] In some of these embodiments, the first composite preform includes a dense layer, with a top layer on one side of the dense layer in the thickness direction and a bottom layer on the other side of the dense layer in the thickness direction; The top layer includes the top plate, the dense layer includes the aluminum alloy powder and the flux powder, and the bottom layer includes aluminum alloy; It also satisfies at least one of the following characteristics (1) to (4): (1) The thickness of the top layer is 5mm~20mm; (2) The thickness of the dense layer is 1.5mm~5mm; (3) The thickness of the bottom layer is 1mm~3mm; (4) The thickness of the aluminum alloy ingot is 30mm~80mm.

[0024] In some of these embodiments, the hot rolling includes: The second composite billet is heated and then subjected to multiple hot rolling processes on a hot rolling mill, with the temperature of the last hot rolling process exceeding 300°C, to obtain a hot-rolled composite plate. The heating temperature is 420℃~470℃, and the temperature is maintained for 4h~6h.

[0025] In some of these embodiments, the annealing temperature is 380°C to 400°C, and the holding time is 2 to 4 hours.

[0026] In some embodiments, the cold rolling includes: The hot-rolled composite plate is subjected to multiple cold rolling processes to obtain a cold-rolled composite plate; wherein the thickness of the cold-rolled composite plate is 0.3mm~2.0mm, and the single-pass reduction of the cold rolling is 20%~30%.

[0027] According to another aspect of the present invention, the present invention provides a pre-embedded flux aluminum alloy composite material, comprising: a pre-embedded flux aluminum alloy composite material prepared by the preparation method described in any of the above embodiments.

[0028] In some embodiments, the pre-embedded flux aluminum alloy composite material includes a composite layer, wherein an aluminum-silicon alloy layer is provided on one side of the composite layer in the thickness direction, and an aluminum alloy layer is provided on the other side of the composite layer in the thickness direction; The aluminum-silicon alloy layer includes 4045 alloy, 4047 alloy or 4343 alloy, the composite layer includes Al-Si aluminum alloy and flux, and the aluminum alloy layer includes 3003 aluminum alloy.

[0029] Implementing the technical solution of the present invention has at least the following beneficial effects: In this invention, an aluminum-silicon alloy plate is used as the top plate to form a box with an open end. A mixed powder containing aluminum alloy powder and flux powder is filled into the box, and the top plate is then added to form a casing. The casing is then subjected to vacuum hot pressing sintering to form a composite billet consisting of an aluminum-silicon alloy layer, a dense powder layer, and an aluminum alloy layer from top to bottom. Subsequently, the aluminum alloy layer side of the composite billet is stacked with an aluminum alloy ingot of the same material and subjected to hot rolling, cold rolling, and annealing. The resulting pre-embedded flux aluminum alloy composite material can effectively improve the interfacial bonding strength and effectively avoid rolling cracking under high flux content.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0032] Figure 1 The diagram shows the process flow chart of the preparation method of the pre-embedded flux aluminum alloy composite material provided by the present invention.

[0033] Figure 2 The diagram shown is a schematic diagram of the pre-embedded flux aluminum alloy composite material structure provided by the present invention.

[0034] Figure 3 The image shown is a metallographic diagram of the pre-embedded flux aluminum alloy composite material provided by the present invention.

[0035] Figure 4 The diagram shown is a process flow chart of an embodiment of the present invention.

[0036] Figure 5 The diagram shown is a schematic diagram of the sheath structure according to an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures: 10 – Composite layer; 20 – Aluminum-silicon alloy layer; 30 – Aluminum alloy layer; 1 – Exhaust pipe; 2 – Top plate; 3 – Box body; 4 – Mixed powder.

[0038] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0045] Currently, when preparing pre-embedded flux aluminum alloy composite materials using the hot-rolling composite method, a temporary sheath is typically used to hot isostatically press a mixture of flux and aluminum alloy powder to form a powder metallurgy ingot in order to pre-composite the flux into the brazing filler layer. The temporary sheath is then removed by milling, and the ingot is subsequently stacked with an aluminum alloy casting as the core material and hot-rolled. However, the powder metallurgy ingot and the cast core material differ significantly in composition, microstructure, and high-temperature rheological stress. When the two are directly stacked and subjected to large deformation during hot rolling, the synergistic deformation capacity is insufficient, and poor bonding, microcracks, or even cracking easily occur at the composite interface. This is especially true when the material needs to be rolled to a thinner specification or when the flux content in the ingot is high, as the ductility of the powder metallurgy layer decreases significantly, further increasing the risk of interface cracking. Furthermore, milling the temporary sheath after hot isostatic pressing not only increases clamping, programming, and machining processes but also causes material loss and introduces cutting stress, making the preparation process cumbersome.

[0046] Through research and analysis, the inventors of this invention discovered that the causes of the aforementioned problems may include: First, due to the difference in microstructure between the powder metallurgy structure of the pre-embedded flux layer and the cast core material, their rheological stress responses during high-temperature compression deformation are inconsistent, resulting in concentrated shear strain at the contact interface and making it difficult to form continuous atomic-level diffusion bonding. Second, when the flux addition increases, there are more brittle flux particles inside the powder layer, further reducing the plastic deformation capacity of the layer itself. During rolling and elongation, cracks are prone to initiate at initially weak points and extend to both sides. Third, the temporary sheath only serves as a forming container and needs to be removed after hot isostatic pressing. This does not contribute to the structure or function of the final product but adds extra complexity to the process and uncertainty in the surface state caused by interface reprocessing.

[0047] In view of the above-mentioned technical problems, the present invention provides a pre-embedded flux aluminum alloy composite material and its preparation method. By transforming the cladding from a temporary process device into a component that participates in the final material composition, and by converting the cladding itself into a functional layer in the composite billet, the interface matching conditions during hot rolling composite are improved. Specifically, an aluminum-silicon alloy plate is used as a top plate, and a box with an open end is formed from the aluminum alloy plate. A mixed powder containing aluminum alloy powder and flux powder is filled into the box, and the top plate is covered to form a cladding. The cladding is subjected to vacuum hot pressing sintering to form a composite billet composed of an aluminum-silicon alloy layer, a dense powder layer, and an aluminum alloy layer from top to bottom. Subsequently, the aluminum alloy layer side of the composite billet is stacked with an aluminum alloy ingot of the same material, and then hot-rolled, cold-rolled, and annealed to obtain the pre-embedded flux aluminum alloy composite material.

[0048] The specific technical solution of the present invention is as follows: In some embodiments of the present invention, a method for preparing a pre-embedded flux aluminum alloy composite material is provided, with reference to... Figure 1 This includes the following steps: S101. Fill the mixed powder into a box with an open end, and place the top plate at the open end to obtain a casing; wherein, the top plate includes an aluminum-silicon alloy; the box includes an aluminum alloy; and the mixed powder includes aluminum alloy powder and flux powder.

[0049] As an example, the box body is made of aluminum alloy, with an opening at one end to facilitate the loading of the mixed powder. The top plate is made of aluminum-silicon alloy, and its size matches the size of the opening in the box. After the mixed powder is added to the box and it is full, the top plate and the box body are connected by welding, ensuring that the interior of the resulting package is completely filled without any gaps. In a preferred embodiment, refer to... Figure 5 To ensure the mixed powder fills the box, vibration or other methods can be used, or a vacuum system can be connected to the vacuum pipe 1 pre-installed on the top plate 2 to evacuate the box 3. Finally, the vacuum pipe opening on the top plate 2 is sealed, thus filling the box with the mixed powder 4. It is understood that the aluminum alloy powder can be made of the same material as the top plate or the box. The flux powder includes, but is not limited to, potassium fluoroaluminate, sodium fluoroborate, etc. The specific shape of the box is not specifically limited in this invention.

[0050] S102. The cladding is subjected to vacuum hot pressing sintering to obtain the first composite blank.

[0051] As an example, the cladding can be vacuum hot-pressed and sintered. Specifically, the cladding can be placed in a graphite mold within a vacuum hot-pressing sintering furnace. The furnace is then equipped with a certain degree of vacuum, and the temperature is raised to a specific level for sintering. Vacuum sintering, i.e., evacuating the furnace, improves the purity of the first composite blank and reduces side reactions between the cladding and oxygen during sintering. Simultaneously, the vacuum level within the cladding effectively reduces the porosity of the first composite blank, making it more compact. Furthermore, the cladding can be pressed during sintering, for example, by using upper and lower pressure heads to apply pressure to the upper and lower surfaces of the cladding. Under high temperature and pressure, the mixed powder within the cladding is compacted and densified, and diffuses and bonds with the inner wall of the cladding. It is understandable that by controlling the vacuum level in the furnace, the sintering temperature range, the magnitude of the bidirectional pressure, the holding time, and the heating rate, the aluminum alloy powder is made to flow and rearrange in a plastic softening state, expelling residual voids and forming diffusion bonding with the inner wall of the cladding, ultimately obtaining a first composite billet with high density and good interfacial bonding between each layer.

[0052] S103. The side of the first composite billet away from the top plate is stacked with the aluminum alloy ingot to form a second composite billet; wherein the material of the aluminum alloy ingot is the same as the material of the box body.

[0053] As an example, the second composite billet obtained through step S102 is stacked with the aluminum alloy ingot, and the aluminum alloy ingot is stacked with the side of the second composite billet away from the top plate near the bottom of the box. The material of the aluminum alloy ingot is the same as that of the box, thus forming the second composite billet.

[0054] S104. The second composite billet is hot-rolled, cold-rolled, and annealed to obtain a pre-embedded flux aluminum alloy composite material.

[0055] As an example, a pre-embedded flux aluminum alloy composite material is obtained by hot rolling, cold rolling, and annealing the second composite billet. It can be understood that after vacuum hot pressing and sintering, the top plate of the cladding directly transforms into an aluminum-silicon alloy layer on the surface of the composite material, the bottom surface of the box transforms into a transition layer that can be homogeneously metallurgically bonded with the subsequent core material ingot, and the internal powder mixture is compacted into a dense pre-embedded flux layer. The resulting second composite billet consists of an aluminum-silicon alloy layer, a dense powder layer, and an aluminum alloy layer from top to bottom, with the bottom material being the same as the aluminum alloy ingot to be composited. When the two are stacked and hot rolled, the two sides of the interface are homogeneous materials, exhibiting highly consistent rheological behavior at high temperatures, and the cooperative deformation capability is fundamentally improved, thus enabling the formation of a reliable metallurgical bond at the interface and effectively suppressing rolling cracking. Simultaneously, the brittle powder layer in the second composite billet is covered in the thickness direction by the upper aluminum-silicon alloy top plate and the lower aluminum alloy bottom plate. During the large deformation process of hot rolling and cold rolling, the main shear stress is borne and transmitted by the upper and lower metal plates with good ductility. The inner powder layer is protected and does not directly bear the shear force. This allows the entire layered structure to maintain coordinated deformation without damage even with a high flux addition ratio, and pre-embedded flux composite materials with high flux content can be obtained.

[0056] Furthermore, in the encapsulation stage, the top plate and the casing are welded together for sealing, and a vacuum is applied to the inside of the encapsulation through a through-hole in the top plate. This ensures that air and adsorbed moisture between the powder particles are fully removed before heating. Once the vacuum level inside the encapsulation is guaranteed, it is then sealed and vacuum hot-pressed for sintering. This process effectively prevents powder oxidation or gas residue from occurring at high temperatures, improving the density of the dense powder layer and the purity of the interlayer interfaces.

[0057] In some embodiments, the weight ratio of aluminum alloy powder to flux powder in the mixed powder is (9~18):(82~91). Exemplarily, the weight ratio of aluminum alloy powder to flux powder can be any one of 9:91, 10:90, 12:88, 15:85, or 18:82, or any ratio between any two. This allows for the stable containment of a high flux content in the composite billet while avoiding cracking during subsequent rolling due to poor plasticity of the powder layer.

[0058] Furthermore, the researchers of this invention discovered that when the flux content is too low, the composite material provides insufficient film-breaking dosage during brazing, failing to effectively remove the oxide film on the aluminum surface, resulting in a reduced spreading area of ​​the molten solder and a decreased welding rate. Conversely, when the flux content is too high, the volume proportion of brittle flux particles in the powder layer increases significantly, disrupting the continuity of the aluminum matrix and reducing the ductility of the dense powder layer after hot pressing and sintering. During subsequent hot rolling deformation, even when protected by an outer metal plate, this highly brittle layer will still develop microcracks that propagate into interlayer separation, leading to product scrap. By limiting the flux content within the aforementioned range, a balance between film-breaking capability and processing deformation capability is achieved. This allows the mixed powder to form a continuous aluminum-silicon phase encapsulating discrete flux particles in a microstructure during sintering through the plastic rheology of the aluminum matrix. The interpenetrating network structure provides better integrity for the brittle powder layer.

[0059] In some embodiments, the aluminum alloy powder includes, but is not limited to, Al-Si alloy powder.

[0060] In some embodiments, the weight ratio of KAlF4 to K2AlF5 in the flux powder is (70-80):(20-30). Exemplarily, the weight ratio of KAlF4 to K2AlF5 can be any one of 70:30, 72:28, 76:24, or 80:20, or any value between any two.

[0061] In some embodiments, the box body includes a bottom plate and side plates. The bottom plate includes, but is not limited to, 3003 aluminum alloy, and the side plates also include, but are not limited to, 3003 aluminum alloy. Exemplarily, the box body includes multiple side plates and at least one bottom plate, with the bottom plate and top plate parallel to each other. The side plates and bottom plate are welded together, forming a box body with a receiving space, allowing the mixed powder to be loaded into the box body. It is understood that the bottom plate and side plates in the box body are made of the same material. Thus, the similarity in material between the box body and the top plate allows for a good fit, which can significantly improve the interfacial bonding strength between the box body and the aluminum alloy ingot when subsequently stacked with the aluminum alloy ingot to prepare a pre-embedded flux aluminum alloy composite material.

[0062] In some embodiments, the aluminum-silicon alloy includes, but is not limited to, any one of alloy 4045, alloy 4047, or aluminum alloy 4343, or other 3-series core materials and 4-series brazing sheaths with different compositions. It is understood that alloy 4045 comprises silicon (Si): 10.0~12.0%, aluminum (Al) balance typically >87%, iron (Fe) ≤0.80%, copper (Cu) ≤0.30%, manganese (Mn) ≤0.15%, magnesium (Mg) ≤0.10%, zinc (Zn) ≤0.20%, titanium (Ti) ≤0.10%, and other individual impurities ≤0.05%. 4047 alloy comprises aluminum (Al) and silicon (Si), with silicon content ranging from approximately 11.0% to 13.0%. It also includes iron (Fe) ≤0.8%, copper (Cu) ≤0.30%, manganese (Mn) ≤0.15%, magnesium (Mg) ≤0.10%, and zinc (Zn) ≤0.20%, as well as other individual impurity elements, each not exceeding 0.05%, totaling no more than 0.15%. 4343 aluminum alloy's main chemical composition includes aluminum (Al) as the matrix, with silicon (Si) content between 6.8% and 8.2%. It also contains trace amounts of copper (Cu) and iron (Fe), specifically: Cu 0.1%, Fe ≤0.5%, Mn ≤0.3%, Mg ≤0.05%, Zn ≤0.25%, and Ti ≤0.15%.

[0063] In some embodiments, the thickness of the top plate is 5mm to 20mm. Exemplarily, the thickness of the top plate can be any one of 5mm, 6mm, 8mm, 10mm, 12mm, 15mm, 18mm or 20mm, or any value between any two.

[0064] In some embodiments, the silicon content in the Al-Si alloy powder is 7% to 12.5% ​​by mass. Exemplarily, the silicon content in the Al-Si alloy powder can be any one of 7%, 7.2%, 7.5%, 8%, 9%, 10%, 10.5%, 11%, 11.5%, 12%, 12.2%, or 12.5%, or any value between any two. If the silicon content is below the above range, the liquidus temperature is high, and the solder fluidity is poor; if it is above the above range, there is more primary silicon, which deteriorates the brazing performance.

[0065] In some embodiments, the median particle size D of the Al-Si alloy powder 50 The particle size ranges from 20 μm to 60 μm. For example, the median particle size D of Al-Si alloy powder... 50 It can be any point value between any one of 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 58μm or 60μm.

[0066] In some embodiments, the oxygen content of the Al-Si alloy powder is less than 300 ppm. Exemplarily, the oxygen content of the Al-Si alloy powder can be any value of 300 ppm, 200 ppm, or 150 ppm and below. It is understood that the oxygen content can be determined using a LECOONH-3000 oxygen-nitrogen-hydrogen analyzer or an inert gas melting-infrared absorption method, and there is no specific limitation thereto.

[0067] In some embodiments, the median particle size D of the flux powder 50 The particle size ranges from 10 μm to 50 μm. For example, the median particle size D of the flux powder... 50 It can be any point value between any one of 10μm, 15μm, 18μm, 20μm, 25μm, 30μm, 40μm or 50μm.

[0068] In some embodiments, the silicon content in the aluminum-silicon alloy is 7% to 12.5% ​​by mass. Exemplarily, the silicon content in the aluminum-silicon alloy can be any one or any value between any two of 7%, 7.2%, 7.5%, 8%, 9%, 10%, 10.5%, 11%, 11.5%, 12%, 12.2%, or 12.5%.

[0069] In some embodiments, the thickness of the side panel is 1mm to 3mm. Exemplarily, the thickness of the side panel can be any one of 1mm, 1.5mm, 2mm or 3mm, or any value between any two.

[0070] In some embodiments, the thickness of the base plate is 1mm to 3mm. Exemplarily, the thickness of the base plate can be any one of 1mm, 1.5mm, 2mm, or 3mm, or any value between any two. By limiting the thickness range of the side plates and / or the base plate, the overall performance of the subsequent product can be guaranteed. If the thickness is too thin, it may affect subsequent hot-rolling lamination; if the thickness is too thick, encapsulation molding is difficult, and the sidewalls need to be cut off later, resulting in a decrease in yield.

[0071] In some embodiments, a V-type powder mixer is used to mix the aluminum alloy powder and flux powder for 2 to 6 hours at a rotation speed of 2 to 6 rpm. Exemplarily, the mixing time can be any one of 2 hours, 4 hours, or 6 hours, or any value between any two; the rotation speed can be any one of 2 rpm, 4 rpm, or 6 rpm, or any value between any two. Using a V-type powder mixer and its low-speed mixing parameters is to avoid significant stratification of the aluminum powder and flux powder with large density differences during mixing, ensuring uniform flux distribution in the final dense powder layer, thereby guaranteeing the consistency of the overall composite material surface properties.

[0072] In some embodiments, prior to vacuum hot pressing sintering, the following steps are also included: The box body and top plate are welded and sealed. A through hole is provided on the top plate, through which a vacuum is drawn into the enclosure. When the vacuum level inside the enclosure is lower than a preset vacuum level, the through hole is sealed. The preset vacuum level is 1×10⁻⁶. -2 Pa.

[0073] For example, refer to Figure 5 To remove air from the gaps between powder particles inside the casing and moisture adsorbed on the powder surface, degassing is required. Connect a vacuum pipe to the through-hole in the top plate, activate the vacuum system, and evacuate the internal space of the sealed casing through this through-hole. Continue evacuation until the vacuum level inside the casing is below 1×10⁻⁶. -2 Pa; After reaching the preset vacuum level, the system is sealed by cold welding or melting while maintaining the vacuum.

[0074] In some embodiments, vacuum hot pressing sintering includes: placing the cladding into a vacuum hot pressing sintering furnace, evacuating the vacuum hot pressing sintering furnace until the vacuum degree of the vacuum hot pressing sintering furnace is lower than 1×10⁻⁶. -2 When Pa, the temperature is increased to the sintering temperature; and pressure is applied to the top and bottom of the cladding.

[0075] For example, a completely sealed enclosure is placed in a graphite mold inside a vacuum hot-pressing sintering furnace. After closing the furnace cavity, the furnace cavity is evacuated again to achieve a vacuum level below 1×10⁻⁶. -2 The Pa level is adjusted to further eliminate interference from ambient gases. Then, the heating program is initiated, and the furnace temperature is rapidly increased from room temperature to the set sintering temperature for sintering. This effectively avoids side reactions between the cladding and oxygen during sintering, improving the alloy purity of the first composite billet. Simultaneously, it further reduces the porosity of the first composite billet, increasing its density and mechanical properties, thereby enhancing the brazing performance of the aluminum alloy composite material.

[0076] Optionally, vacuum hot pressing sintering also satisfies at least one of (1) to (3): (1) the sintering temperature is 450℃ to 550℃; (2) the applied pressure is 30MPa to 80MPa, and the holding time is 2h to 5h; (3) the heating rate is any one of 8℃ / min, 10℃ / min, 12℃ / min, or 15℃ / min, or any value between any two. For example, the sintering temperature can be any one of 450℃, 500℃, or 550℃, or any value between any two; the applied pressure can be any one of 30MPa, 50MPa, or 80MPa, or any value between any two. By limiting the heating rate, the temperature difference between the inside and outside of the cladding can be effectively controlled. An excessively fast heating rate may cause a large temperature gradient between the cladding wall and the internal powder, resulting in uneven thermal expansion, which in turn causes irregular deformation of the cladding and affects the geometric accuracy of the final composite blank. Simultaneously, under the combined effects of high temperature and high pressure, the mixed powder inside the cladding undergoes a violent compaction and densification process. Within this temperature range, the Al-Si alloy powder is in a high-temperature softened or even partially semi-solid state. Driven by triaxial compressive stress, it undergoes plastic rheology, gradually filling the voids between particles and causing the remaining gas to be squeezed out or pressed into the aluminum matrix to form tiny, dispersed closed pores.

[0077] In some embodiments, the first composite blank includes a dense layer, a top layer on one side of the dense layer in the thickness direction, and a bottom layer on the other side of the dense layer in the thickness direction; the top layer includes a top plate, the dense layer includes aluminum alloy powder and flux powder, and the bottom layer includes aluminum alloy. Exemplarily, the aluminum-silicon alloy layer formed by the original top plate is the top layer, the dense layer formed by densifying the mixed powder, and the aluminum alloy layer formed by the bottom of the original housing.

[0078] Optionally, at least one of the following (1) to (4) must also be satisfied: (1) the thickness of the top layer can be any value of 5 mm, 10 mm or 20 mm; (2) the thickness of the dense layer can be any value of 1.5 mm, 3 mm or 5 mm; (3) the thickness of the bottom layer can be any value of 1 mm, 2 mm or 3 mm; (4) the thickness of the aluminum alloy ingot can be any value of 30 mm, 50 mm or 80 mm.

[0079] In some embodiments, hot rolling includes heating a second composite billet and then performing multiple hot rolling operations on a hot rolling mill, with the temperature of the final hot rolling being greater than 300°C, to obtain a hot-rolled composite plate.

[0080] Optionally, the heating temperature is any value among 420℃, 450℃ or 470℃, and the holding time is any value among 4h to 6h.

[0081] For example, multiple hot rolling can be performed through 7 passes, achieving a total reduction rate of 92.5%, ultimately thinning the composite to an intermediate thickness of 6 mm, with a final rolling temperature of 350°C. Alternatively, it can be performed through 9 passes, resulting in an 8 mm thick hot-rolled plate, with a final rolling temperature of 330°C. During the multi-pass hot rolling process, the rolling force acts on the entire composite through the rolls. The top cladding layer, composed of an aluminum-silicon alloy layer and a dense powder layer, and the hot-rolled composite plate with embedded flux, experience relatively limited shear stress during this process. The inventors of this invention discovered that the intense shear deformation during hot rolling is mainly borne by the outer aluminum-silicon alloy plate, the bottom 3003 aluminum alloy plate, and the 3003 ingot core material. The brittle, dense powder layer in the middle, with poor plasticity, does not directly bear the strong in-plane shear force; its deformation is mainly due to compressive stress-driven thinning in the thickness direction and planar extension under the constraint of the upper and lower rigid layers. This stress shielding effect enables the stable rolling of high flux-content composite billets. Meanwhile, the bottom surface of the composite billet and the two sides of the interface of the 3003 ingot are made of the same material. Under high temperature and high pressure, atoms can fully diffuse across the interface, achieving atomic-level metallurgical bonding. The bonding strength far exceeds the level of mechanical interlocking of dissimilar materials.

[0082] In some embodiments, the annealing temperature can be any one of 380°C, 390°C, 400°C, or any value between any two, and the holding time can be any one of 2h, 3h, or 4h, or any value between any two.

[0083] By setting the heating temperature and holding time after the second composite billet is stacked with the first composite billet, the materials on both sides of the interface reach a suitable plastic deformation temperature range. Multiple hot rolling passes are then performed, maintaining the final rolling temperature above the set value to ensure sufficient atomic diffusion at the interface and achieve a strong metallurgical bond. Subsequent cold rolling uses controlled single-pass reduction to gradually thin the sheet to the target thickness, avoiding stress concentration and delamination caused by excessive single-pass deformation. Finally, annealing eliminates processing stress and restores the sheet's plasticity, resulting in a pre-embedded flux aluminum alloy composite material that possesses both mechanical and brazing properties.

[0084] In some embodiments, cold rolling includes: subjecting a hot-rolled composite plate to multiple cold rolling processes to obtain a cold-rolled composite plate; wherein the thickness of the cold-rolled composite plate is 0.3 mm to 2.0 mm, and the single-pass reduction of the cold rolling is 20% to 30%.

[0085] For example, to avoid interlaminar shear failure or edge cracking caused by excessive deformation in a single pass during cold rolling, the reduction in each rolling pass is limited. The reduction in a single pass is controlled within the range of 20% to 30%. For instance, using 5 passes of cold rolling with a reduction of 20% to 25% per pass, the sheet material is rolled from a thickness of 6 mm to a finished thickness of 0.8 mm; or using 7 passes of cold rolling, the sheet material is rolled from a thickness of 8 mm to a finished thickness of 1.2 mm. By limiting the reduction in a single pass to no more than 30%, it can be ensured that the layers do not separate due to excessive stress concentration during continuous synergistic deformation, enabling the stable production of ultra-thin pre-embedded flux aluminum alloy composite materials with a thickness as low as 0.3 mm.

[0086] In some embodiments, reference is made to Figure 4 The preparation method of pre-embedded flux aluminum alloy composite material includes the following steps: Step 1: Prepare the sleeve Material selection: Top plate: Aluminum-silicon alloy rolled plate (such as 4045, 4047 alloy), Si content 7~12.5%, thickness 5~20mm.

[0087] Bottom and side panels: 3003 aluminum alloy rolled plate, thickness 1~3mm.

[0088] Bending and welding: Cut the 3003 into a base plate and a side plate. Bend the side plate into a rectangle and weld it to the base plate to form an open square box. Use an Al-Si plate as the top cover, leaving a pre-filled opening for subsequent welding.

[0089] Step 2: Preparation of Mixed Powders Weigh out the following by weight percentage: Al-Si alloy powder (Si content 7%~12.5%), D 50 =20~60μm, oxygen content <300ppm. Potassium fluoroaluminate flux powder, D 50 =10~50μm. The weight ratio of flux powder to Al-Si alloy powder is (9~18):(91~82).

[0090] The two powders are mixed evenly in a V-type mixer for 2 to 6 hours at a speed of 2 to 6 r / min.

[0091] Step 3: Powder Filling and Encapsulation Fill the mixed powder into a 3003 aluminum alloy square box and vibrate until the powder volume no longer decreases. Cover with the Al-Si top plate and weld the top plate to the side plates using a fusion welding method. Connect a vacuum system to the pre-reserved evacuation port on the top plate and evacuate until the vacuum level inside the casing is below 1×10⁻⁶. -2 Pa. Seal off the extraction tube to obtain a completely sealed enclosure.

[0092] Step 4: Vacuum hot pressing sintering The sealing sleeve is placed into the graphite mold in the vacuum hot pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 1×10⁻⁶. -2 The temperature is increased to the set temperature at a heating rate of 10℃ / min, and the cladding is pressurized bidirectionally through the upper and lower pressure heads. Process parameters: sintering temperature 450~550℃, sintering pressure 30~80MPa, holding time 2~5 hours.

[0093] After cooling, the material is removed to obtain the first composite preform. The structure of the first composite preform at this time is as follows: Top layer: Aluminum-silicon alloy rolled plate (thickness 5~20mm, thickness remains unchanged).

[0094] Intermediate layer: Al-Si + flux dense composite layer (thickness 1.5~5mm, volume shrinkage rate about 50%).

[0095] Base plate and side plates: 3003 steel plate.

[0096] Step 5: Hot rolling composite Prepare a 3003 aluminum alloy ingot as the core material, with a thickness of 30-80 mm and a smooth milled surface. Stack the 3003 bottom surface of the first composite billet with the 3003 ingot (Al-Si top surface of the composite billet facing upwards). Heat the stacked billet to 420-470℃ and hold for 4-6 hours. Perform multiple hot rolling passes on a hot rolling mill, with a final rolling temperature greater than 300℃, to an intermediate thickness of 5-8 mm. Because the bottom surface of the first composite billet and the core material are both homogeneous 3003, the synergistic deformation ability during hot rolling is excellent, resulting in a high-strength metallurgical bonding interface.

[0097] Step Six: Cold Rolling and Finished Product Annealing The hot-rolled sheet is cooled to room temperature. Multiple cold rolling passes are then performed until the final finished thickness is 0.3~2.0 mm. The reduction per cold rolling pass is controlled at 20~30%. Depending on the product condition requirements, the finished product is annealed at 380~400℃ for 2~4 hours. This yields a pre-embedded flux aluminum alloy composite material.

[0098] In some embodiments of the present invention, reference is made to Figure 2 and Figure 3 A pre-embedded flux aluminum alloy composite material is provided, comprising: the pre-embedded flux aluminum alloy composite material prepared by the preparation method in any of the above embodiments.

[0099] The pre-embedded flux aluminum alloy composite material includes a composite layer 10, an aluminum-silicon alloy layer 20 on one side of the composite layer in the thickness direction, and an aluminum alloy layer 30 on the other side of the composite layer in the thickness direction. This pre-embedded flux aluminum alloy composite material exhibits excellent brazing performance.

[0100] In this embodiment, the aluminum-silicon alloy layer 20 comprises 4045 alloy or 4047 alloy, the composite layer 10 comprises Al-Si aluminum alloy and flux, and the aluminum alloy layer 30 comprises 3003 aluminum alloy. The pre-embedded flux aluminum alloy composite material in this embodiment has all the beneficial effects and advantages of the composite materials in any of the above embodiments, which will not be elaborated here.

[0101] Since the pre-embedded flux aluminum alloy composite material provided in this embodiment adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0102] The present invention will be described in detail below with reference to the accompanying drawings and examples. However, the implementation and protection of the present invention are not limited thereto. The following embodiments are only some embodiments of the present invention and are not intended to limit the present invention.

[0103] Example 1 1) Package parameters Top plate: 4045 aluminum alloy rolled plate (aluminum-silicon alloy plate, silicon content is 10.0%), 6.0mm thick, with reserved air extraction pipe.

[0104] The bottom and side plates of the box are made of 3003 aluminum alloy rolled plate with a thickness of 1.0mm.

[0105] Internal height of the sleeve: 20mm.

[0106] 2) Powder mixing parameters Al-Si alloy powder: silicon content is 10.0%, D 50 =40μm, oxygen content 250ppm. Flux powder: KAlF4-K2AlF5 mixed powder, weight ratio 70:30, D 50 =25μm. Mixing ratio: 88wt% Al-Si alloy powder, 12wt% flux powder. Mixing method: V-type powder mixer, speed 5r / min, mixing time 4h.

[0107] 3) Filling powder and encapsulation Fill the mixed powder into a 3003 aluminum alloy square box and vibrate until the powder volume no longer decreases. Cover with the Al-Si top plate and weld the top plate to the side plates using a fusion welding method. Connect a vacuum system to the pre-reserved evacuation port on the top plate and evacuate until the vacuum level inside the casing is below 1×10⁻⁶. -2 Pa. Seal off the extraction tube to obtain a completely sealed enclosure.

[0108] 4) Vacuum hot pressing sintering The sealing sleeve is placed into the graphite mold in the vacuum hot pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 2×10⁻⁶. -2 The temperature begins to rise after Pa.

[0109] Temperature: 500℃; Pressure: bidirectional pressurization, 50MPa; Holding time: 4h; Heating rate: 10℃ / min. Cooling method: Cool to room temperature with the furnace.

[0110] 5) Hot-rolled composite The first composite blank after hot pressing and sintering has a structure of aluminum-silicon alloy plate-intermediate composite layer (Al-Si alloy powder + flux) / 3003 aluminum alloy. The surface of the blank is cleaned and flattened, with a thickness of about 10mm.

[0111] Aluminum alloy ingot: The surface of the 3003 aluminum alloy ingot is milled flat and the thickness is 80mm.

[0112] Overlay method: Double-sided composite of brazed functional layers, i.e., first composite billet / 3003 ingot / first composite billet, wherein the 3003 bottom surface of the first composite billet is overlapped with the 3003 ingot. Heating temperature: 480℃; holding time: 5h; hot rolling passes: 7 passes, total reduction rate 92.5%, final rolling thickness 6mm; final rolling temperature: 350℃.

[0113] 6) Cold rolling and annealing processes Cold rolling passes: 5 passes, single pass reduction 20-25%, final rolled thickness 0.8mm. Finished product annealing: 390℃, hold for 3 hours, air cool.

[0114] Example 2 1) Package parameters Top plate: 4047 aluminum alloy rolled plate (aluminum-silicon alloy plate, silicon content is 12.0%), thickness 10mm.

[0115] The bottom and side panels of the box are made of 3003 aluminum alloy rolled plate with a thickness of 2.0mm.

[0116] Internal height of the sleeve: 30mm.

[0117] 2) Powder mixing parameters Al-Si alloy powder: silicon content is 12.0%, D 50 =50μm, oxygen content 280ppm.

[0118] Flux powder: KAlF4-K2AlF5 mixed powder, weight ratio 76:24, D 50 =35μm.

[0119] Mixing ratio: 85wt% Al-Si alloy powder, 15wt% flux powder.

[0120] Mixing method: Double cone mixer, speed 4r / min, mixing time 5h.

[0121] 3) Filling powder and encapsulation Fill the mixed powder into a 3003 aluminum alloy square box and vibrate it until the powder volume no longer decreases.

[0122] Cover with an Al-Si top plate and weld the top plate to the side plate using a fusion welding method to seal them.

[0123] Connect the vacuum system to the pre-reserved evacuation port on the top plate and evacuate until the vacuum level inside the casing is below 1×10⁻⁶. - 2 Pa.

[0124] Seal off the extraction tube to obtain a completely sealed enclosure.

[0125] 4) Hot Isostatic Pressing Process The sealing sleeve is placed into the graphite mold in the vacuum hot pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 1×10⁻⁶. -2 The temperature begins to rise after Pa.

[0126] Temperature: 480℃; Pressure: bidirectional pressurization, 80MPa; Holding time: 2h; Heating rate: 8℃ / min.

[0127] 5) Hot rolling composite process The first composite blank after hot pressing and sintering has a structure of aluminum-silicon alloy plate-intermediate composite layer (Al-Si alloy powder + flux) / 3003 aluminum alloy. The surface of the blank is cleaned and flattened, and the size is about 400mm×300mm×15mm.

[0128] Overlay method: single-sided composite of brazed functional layers, namely the first composite billet / 3003 ingot, wherein the 3003 bottom surface of the first composite billet is overlapped with the 3003 ingot.

[0129] Aluminum alloy ingot: The surface of the 3003 aluminum alloy ingot is milled flat, and the size is 400mm×300mm×135mm.

[0130] Heating temperature: 470℃; holding time: 6h; hot rolling passes: 9 passes, final rolling thickness: 8mm, final rolling temperature: 330℃.

[0131] 6) Cold rolling and annealing processes Cold rolling passes: 7 passes, final rolling thickness 1.2mm. Finished product annealing: 380℃, hold for 4 hours, air cooling.

[0132] Example 3 1) Package parameters Top plate: 4343 aluminum alloy rolled plate (aluminum-silicon alloy plate, silicon content is 7.5%), thickness 11mm.

[0133] The bottom and side panels of the box are made of 3003 aluminum alloy rolled sheet, 3mm thick. The internal dimensions of the casing (length × width × height) are 520mm × 420mm × 50mm.

[0134] 2) Powder mixing parameters Al-Si alloy powder: silicon content is 7.5%, D 50 =30μm, oxygen content 220ppm. Flux powder: KAlF4-K2AlF5 mixed powder, weight ratio 80:20, D 50 =15μm.

[0135] Mixing ratio: 91 wt% Al-Si alloy powder, 9 wt% flux powder. Mixing method: V-type powder mixer, speed 6 r / min, mixing time 3 h.

[0136] 3) Filling powder and encapsulation Fill the mixed powder into a 3003 aluminum alloy square box and vibrate until the powder volume no longer decreases. Cover with the Al-Si top plate and weld the top plate to the side plates using a fusion welding method. Connect a vacuum system to the pre-reserved evacuation port on the top plate and evacuate until the vacuum level inside the casing is below 1×10⁻⁶. -2 Pa.

[0137] Seal off the extraction tube to obtain a completely sealed enclosure.

[0138] 4) Vacuum hot pressing sintering process The sealing sleeve is placed into the graphite mold in the vacuum hot pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 3×10⁻⁶. -2 Heating begins after Pa. Hot pressing sintering temperature: 520℃; hot pressing sintering pressure: 30MPa; holding time: 5h; heating rate: 12℃ / min.

[0139] 5) Hot rolling composite process The first composite blank after hot pressing and sintering has a structure of aluminum-silicon alloy plate-intermediate composite layer (Al-Si alloy powder + flux) / 3003 aluminum alloy. The surface of the blank is cleaned and flattened, and the edges are sawn. The size is about 500mm×400mm×25mm.

[0140] Overlay method: double-sided composite of brazed functional layers, namely, first composite billet / 3003 ingot / first composite billet, wherein the 3003 bottom surface of the first composite billet is overlapped with the 3003 ingot.

[0141] Aluminum alloy ingot: 3003 aluminum alloy ingot with a smooth milled surface, dimensions 520mm×420mm×170mm. Heating temperature: 500℃; holding time: 4; hot rolling passes: 6 passes, final rolling thickness 5mm, final rolling temperature 380℃.

[0142] 6) Cold rolling and annealing processes Cold rolling passes: 4 passes, final rolling thickness 0.5mm. Finished product annealing: 400℃, hold for 2 hours, air cooling.

[0143] Example 4 The only difference between Example 4 and Example 1 is the mixing ratio: 82 wt% Al-Si alloy powder and 18 wt% flux powder.

[0144] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the Comparative Example uses hot pressing sintering instead of vacuum hot pressing sintering. Specifically: The sealed sleeve is placed into the graphite mold in the hot-press sintering furnace, and the temperature is initially raised to 500℃; pressure: bidirectional pressure, 50MPa; holding time: 4h; heating rate: 10℃ / min. Cooling method: cooled to room temperature in the furnace.

[0145] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the material of the box body is different from that of the aluminum alloy ingot. Specifically: the bottom plate and side plates of the box body are made of 7075 aluminum alloy rolled plate with a thickness of 1.0 mm. The aluminum alloy ingot is made of 3003 aluminum alloy ingot with a milled and smooth surface and a thickness of 80 mm.

[0146] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the aluminum alloy ingot is stacked with the first composite billet on the side near the top plate. Specifically, the stacking method is a double-sided composite with brazed functional layers, i.e., first composite billet / 3003 ingot / first composite billet, wherein the 4045 top plate of the first composite billet is stacked with the 3003 ingot.

[0147] Test example: 1. Thickness: Measured using a micrometer.

[0148] 2. Interface bonding strength: The interface bonding strength was tested using an electronic universal testing machine at a tensile speed of 5 mm / min.

[0149] 3. Brazing performance: Tested according to GB / T 11364-2008 "Test Method for Wetting Properties of Brazing Alloy". A Φ6mm×2mm cylindrical sample was cut from the composite material and placed in the center of a 40mm×40mm×2mm 3003 aluminum test plate. Under a nitrogen protective atmosphere, the sample was heated from room temperature to 598~605℃ for 24 minutes and held for 4~6 minutes. The spread area was measured using image analysis software, and the average value was calculated from three tests. Metallographic examination of the brazed joint cross-section was performed to check for fullness of the brazed joint. Visual inspection and scanning electron microscopy (SEM) energy dispersive spectroscopy analysis were conducted to determine the presence and quantity of flux residue.

[0150] The test results are shown in Table 1.

[0151] Table 1 As can be seen from Table 1, the pre-embedded flux aluminum alloy composite material prepared by the preparation method of the present invention has good interfacial bonding strength and good brazing performance, and no visible flux residue is visible on the surface after brazing.

[0152] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0153] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0154] It should be noted that the terms "and / or" or " / " used herein are merely descriptions of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The singular forms "a," "described," and "the" used in the embodiments of the invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0155] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a pre-embedded flux aluminum alloy composite material, characterized in that, Includes the following steps: The mixed powder is filled into a box with an open end, and a top plate is placed at the open end to obtain a casing; wherein, the top plate comprises an aluminum-silicon alloy; the box comprises an aluminum alloy; and the mixed powder comprises aluminum alloy powder and flux powder; The casing is subjected to vacuum hot pressing sintering to obtain the first composite blank; The first composite blank is stacked with an aluminum alloy ingot on the side away from the top plate to form a second composite blank; wherein the material of the aluminum alloy ingot is the same as the material of the box body; The second composite billet is hot-rolled, cold-rolled, and annealed to obtain the pre-embedded flux aluminum alloy composite material.

2. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 1, characterized in that, In the mixed powder, the weight ratio of the aluminum alloy powder to the flux powder is (9~18):(82~91). And / or, the aluminum alloy powder includes Al-Si alloy powder; And / or, the flux powder is a KAlF4-K2AlF5 mixed powder, wherein the weight ratio of KAlF4 to K2AlF5 is (70-80):(20-30).

3. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 2, characterized in that, The box body includes a bottom plate and side plates, the bottom plate is made of 3003 aluminum alloy, and the side plates are made of 3003 aluminum alloy; And / or, the aluminum-silicon alloy includes any one of alloy 4045, alloy 4047, or aluminum alloy 4343; And / or, the thickness of the top plate is 5mm to 20mm.

4. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 3, characterized in that, Satisfying at least one of features (1) to (8): (1) The silicon content in the Al-Si alloy powder is 7%~12.5% ​​by mass; (2) The median particle size D of the Al-Si alloy powder 50 The thickness ranges from 20μm to 60μm. (3) The oxygen content of the Al-Si alloy powder is less than 300 ppm; (4) The median particle size D of the flux powder 50 The range is 10μm to 50μm; (5) In the aluminum-silicon alloy, the silicon content is 6.8%~13% by mass; (6) The thickness of the side plate is 1mm~3mm; (7) The thickness of the base plate is 1mm~3mm; (8) The mixed powder is mixed using a V-type powder mixer to mix the aluminum alloy powder and the flux powder. The mixing time is 2h~6h and the rotation speed is 2r / min~6r / min.

5. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 1, characterized in that, Before the vacuum hot pressing sintering, the process also includes: The box body and the top plate are welded and sealed. A through hole is provided on the top plate. A vacuum is drawn into the sleeve through the through hole. When the vacuum degree inside the sleeve is less than the preset vacuum degree, the through hole is sealed. The preset vacuum degree is 1×10⁻⁶. -2 Pa.

6. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 1, characterized in that, The vacuum hot pressing sintering includes: The cladding is placed in a vacuum hot-pressing sintering furnace, and the furnace is evacuated until the vacuum level is below 1×10⁻⁶. -2 When Pa, the temperature is increased to the sintering temperature; and pressure is applied to the top and bottom of the casing. The vacuum hot pressing sintering also satisfies at least one of the following characteristics (1) to (3): (1) The sintering temperature is 450℃~550℃; (2) The applied pressure is 30MPa~80MPa, and the holding time is 2h~5h; (3) The heating rate is 8~15℃ / min.

7. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 1, characterized in that, The first composite preform includes a dense layer, with a top layer on one side of the dense layer in the thickness direction and a bottom layer on the other side of the dense layer in the thickness direction; The top layer includes the top plate, the dense layer includes the aluminum alloy powder and the flux powder, and the bottom layer includes aluminum alloy; It also satisfies at least one of the following characteristics (1) to (4): (1) The thickness of the top layer is 5mm~20mm; (2) The thickness of the dense layer is 1.5mm~5mm; (3) The thickness of the bottom layer is 1mm~3mm; (4) The thickness of the aluminum alloy ingot is 30mm~80mm.

8. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 1, characterized in that, The hot rolling includes: The second composite billet is heated and then subjected to multiple hot rolling processes on a hot rolling mill, with the temperature of the last hot rolling process exceeding 300°C, to obtain a hot-rolled composite plate. The heating temperature is 420℃~470℃, and the temperature is maintained for 4h~6h; And / or, the annealing temperature is 380℃~400℃, and the holding time is 2h~4h.

9. The method for preparing the pre-embedded flux aluminum alloy composite material according to claim 8, characterized in that, The cold rolling includes: The hot-rolled composite plate is subjected to multiple cold rolling processes to obtain a cold-rolled composite plate; wherein the thickness of the cold-rolled composite plate is 0.3mm~2.0mm, and the single-pass reduction of the cold rolling is 20%~30%.

10. A pre-embedded flux aluminum alloy composite material, characterized in that, include: The pre-embedded flux aluminum alloy composite material prepared by the preparation method according to any one of claims 1 to 9; The pre-embedded flux aluminum alloy composite material includes a composite layer, wherein an aluminum-silicon alloy layer is provided on one side of the composite layer in the thickness direction, and an aluminum alloy layer is provided on the other side of the composite layer in the thickness direction; The aluminum-silicon alloy layer includes 4045 alloy, 4047 alloy or 4343 alloy, the composite layer includes Al-Si aluminum alloy and flux, and the aluminum alloy layer includes 3003 aluminum alloy.

Images