Aluminum alloy composite material of light-weight new energy automobile radiator and preparation process of aluminum alloy composite material

Abstract

The invention discloses an aluminum alloy composite material of a light-weight new energy automobile radiator and a preparation process of the aluminum alloy composite material, and belongs to the technical field of aluminum alloy casting. The process comprises the following steps: generating TiB2 particles in a core layer melt in situ to prepare a core layer blank; atomizing a surface layer melt containing Sc and Zr, injecting hydrophobic modified iron particles, and depositing on the surface of the core layer to form a composite blank; and finally, a finished product is obtained through cold rolling and annealing. Through TiB2 reinforcement and microalloying, equal-strength matching of the core layer and the anti-corrosion layer is achieved, and the material is allowed to be greatly thinned; the interface thermal resistance is eliminated through spray deposition, a dual anti-corrosion mechanism is established with the help of hydrophobic iron particles, and the problems that a traditional aluminum alloy composite material for the radiator is low in strength, limited in heat conduction and poor in corrosion resistance are solved.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy casting technology, and in particular to an aluminum alloy composite material for a lightweight new energy vehicle radiator and its preparation process. Background Technology

[0002] As a core component of the thermal management system, the radiator in new energy vehicles is crucial for ensuring the safe and stable operation of the battery, motor, and electronic control system under high-power conditions. With the continuous pursuit of lightweighting and energy efficiency in vehicle manufacturing, radiator materials must maintain or even improve their structural strength and thermal conductivity while reducing weight. Aluminum alloys, due to their excellent thermal conductivity, formability, and low density, are widely used in radiator manufacturing. However, in the pursuit of ultimate lightweighting, existing technologies face two prominent technical challenges:

[0003] Firstly, reducing material thickness to reduce weight usually leads to a decrease in overall structural strength, which can cause the radiator to deform, crack, or fail prematurely under the high heat load generated by fast charging and the high frequency vibration environment during vehicle operation.

[0004] Secondly, traditional multi-layer composite structures (such as rolled composite plates) often have micro-oxide films, air gaps, or incomplete metallurgical bonding areas between the core layer and the anti-corrosion layer. These interface defects introduce significant additional thermal resistance, weakening the efficient transfer of heat from the heat source to the cooling medium, thus limiting the high thermal conductivity of the material itself.

[0005] Therefore, it is necessary to provide a lightweight aluminum alloy composite material for new energy vehicle radiators and its preparation process to solve the above problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a lightweight aluminum alloy composite material for a new energy vehicle radiator and its preparation process.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator, comprising the following steps:

[0008] S1. Prepare the core layer melt, wherein the core layer melt comprises aluminum, manganese, copper and zirconium;

[0009] S2. Introduce reactive salts into the core layer melt to generate TiB2 nano-reinforcing particles through in-situ reaction. After casting and surface treatment, obtain the core layer blank and preheat the core layer blank.

[0010] S3. Prepare a surface melt, wherein the surface melt comprises aluminum, zinc, magnesium, iron, silicon, scandium, and zirconium;

[0011] S4. The surface melt is atomized into droplet streams, and iron microparticles modified with hydrophobic properties are injected into the droplet streams in the atomization area, so that the droplet streams carrying iron microparticles are deposited on the surface of the core layer billet to form a composite billet.

[0012] S5. The composite billet is heated and hot-rolled in multiple passes to form a metallurgical bonding interface between the core billet and the deposited layer.

[0013] S6. The hot-rolled strip is subjected to cold rolling deformation and finished product annealing to obtain aluminum alloy composite material.

[0014] In a preferred embodiment of the present invention, the core melt comprises the following components by mass percentage: 1.2% to 1.8% manganese, 0.5% to 1.0% copper, 0.1% to 0.2% zirconium, 0.05% to 0.15% titanium, 0.02% to 0.06% boron, with the balance being aluminum and unavoidable impurities.

[0015] In a preferred embodiment of the present invention, the surface melt comprises the following components by mass percentage: zinc 1.0%–3.5%, magnesium 0.2%–0.8%, iron 0.15%–0.4%, silicon 0.1%–0.3%, scandium 0.15%–0.35%, zirconium 0.1%–0.2%, with the balance being aluminum and unavoidable impurities.

[0016] In a preferred embodiment of the present invention, the specific method for generating TiB2 nano-reinforced particles in in-situ in step S2 is as follows: the core layer melt is heated to 750℃-800℃, dried potassium fluorotitanate and potassium fluoroborate are added, and electromagnetic stirring is applied at the same time as the addition.

[0017] The electromagnetic stirring frequency is 15Hz-35Hz, the power is 5kW-15kW, and the continuous reaction time is 15-30min.

[0018] In a preferred embodiment of the present invention, the preheating is to preheat the surface-treated core layer blank to 300°C-450°C.

[0019] In a preferred embodiment of the present invention, in step S4, the iron microparticles modified with hydrophobic surface have a particle size of 1μm-10μm and are composed of a pure iron core and a thin layer of organosilane coupling agent coated on its surface.

[0020] The injection process is as follows: the iron microparticles are fed into the low-pressure zone at the center of the atomizing cone by a powder feeding device, and the microparticles are captured by the surface tension of the droplets.

[0021] In a preferred embodiment of the present invention, the process parameters for surface melt atomization and deposition in step S4 include:

[0022] The atomizing medium is high-purity nitrogen, the atomization pressure is 0.8MPa-1.5MPa, the dew point temperature of nitrogen is controlled below -60℃, and the oxygen content is controlled below 5ppm.

[0023] The deposition chamber pressure was maintained between -0.05 MPa and -0.1 MPa.

[0024] The velocity of the liquid droplets carrying iron particles impacting the surface of the core layer blank is not less than 150 m / s;

[0025] The deposition thickness of the surface melt is controlled to be 3% to 5% of the total thickness of the composite billet.

[0026] In a preferred embodiment of the present invention, in step S5, the multi-pass hot rolling adopts a variable temperature rolling process, specifically including:

[0027] Heat the composite preform to 400℃-500℃ and hold for 2-6 hours;

[0028] The initial passes are conducted at 480℃-500℃, with a reduction rate of 15%-25% in the first pass.

[0029] Subsequent passes will be conducted at 400℃-420℃.

[0030] The total deformation during hot rolling shall not be less than 80%;

[0031] After hot rolling, the strip is subjected to laminar flow cooling at a rate of 15℃ / s-30℃ / s.

[0032] In a preferred embodiment of the present invention, in step S6, the total deformation amount of the cold rolling deformation is 75% to 90%;

[0033] The method for annealing the finished product is as follows: the cold-rolled strip is fed into an annealing furnace, the annealing temperature is 280℃-350℃, and the holding time is 1-10min; wherein, the heating rate in the annealing heating stage in the range of 200℃-280℃ is not less than 50℃ / s.

[0034] An aluminum alloy composite material is prepared using the aforementioned preparation process for a lightweight new energy vehicle radiator aluminum alloy composite material.

[0035] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0036] (1) This invention provides a process for preparing lightweight aluminum alloy composite materials for new energy vehicle radiators. The composite material is prepared using a combination of an in-situ TiB2-reinforced core layer and a Sc, Zr-containing surface layer, employing spray deposition and hot rolling processes. The clean TiB2 particles generated in situ strengthen the core layer, while the surface layer exhibits a yield strength ≥150 MPa through Al3(Sc,Zr) nanophase precipitation, achieving equal strength matching between the core layer and the anti-corrosion layer. Compared to the traditional soft anti-corrosion layer which does not contribute strength, this invention eliminates the strength dilution effect, allowing the anti-corrosion layer to effectively share the load. Furthermore, while ensuring compressive and burst resistance, the radiator wall thickness can be reduced by 10%-15%, achieving a balance between extreme lightweighting and structural safety.

[0037] (2) This invention utilizes the kinetic energy effect of solid iron microparticles acting as micro-projectiles in the jet stream to physically break up the hard oxide film on the surface of the high-strength core layer, resulting in a highly discontinuous state of the interfacial oxide film. This in-situ film-breaking mechanism overcomes the technical obstacle of simply impacting aluminum droplets to break up the oxide film of the high-alloy core layer, eliminating interfacial thermal resistance. Furthermore, it breaks through the heat transfer bottleneck, ensuring that the material can easily cope with the transient high heat flow impact under fast charging conditions, significantly improving heat dissipation efficiency.

[0038] (3) This invention unexpectedly discovered that by introducing hydrophobically modified iron microparticles, the corrosion kinetics of the anti-corrosion layer was altered. The dispersed iron microparticles dispersed the corrosion current, causing the corrosion morphology to change from a high aspect ratio longitudinal perforation type to a low aspect ratio transverse layered erosion type, significantly delaying the penetration of the radiator wall thickness. At the same time, the uniform distribution of micro-cells reduced the differences in surface electrochemical activity, significantly reducing the variance of the surface potential distribution.

[0039] (4) This invention employs 15Hz-35Hz electromagnetic stirring to assist in the in-situ reaction, utilizing fluid shear force to break the agglomerate chains in the early stages of TiB2 formation, allowing it to disperse. This ensures that TiB2 fully utilizes its Orowan strengthening and grain boundary pinning effects, significantly improving its strength and heat resistance. Compared to low-frequency agglomeration or high-frequency stirring dead zones, this specific frequency ensures the monodispersity of the reinforcing phase. Consequently, it maintains stable microstructure and properties during thermal cycling and processing, preventing stress concentration and crack initiation caused by particle segregation. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1This is a process flow diagram of the preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0044] Figure 1 A process flow diagram of the preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to an embodiment of the present invention is shown. The preparation process includes the following steps:

[0045] Step S1: Prepare the core layer melt, which includes aluminum, manganese, copper and zirconium;

[0046] Step S2: Introduce reactive salts into the core layer melt to generate TiB2 nano-reinforcing particles through in-situ reaction. After casting and surface treatment, obtain the core layer billet and preheat the core layer billet.

[0047] Step S3: Prepare the surface melt, which includes aluminum, zinc, magnesium, iron, silicon, scandium and zirconium;

[0048] Step S4: Atomize the surface melt into droplets, inject surface-hydrophobic modified iron particles into the droplets in the atomization area, so that the droplets carrying iron particles are deposited on the surface of the core billet to form a composite billet;

[0049] Step S5: The composite billet is heated and hot rolled in multiple passes to form a metallurgical bonding interface between the core billet and the deposited layer.

[0050] Step S6: Cold rolling deformation and finished product annealing are performed on the hot-rolled strip to obtain aluminum alloy composite material.

[0051] This invention's fabrication process employs an equal-strength matching design between an in-situ TiB2-reinforced core layer and a Sc / Zr microalloyed anti-corrosion layer. Combined with a hydrophobic-micro-battery dual anti-corrosion mechanism introduced by hydrophobically modified iron microparticles, it fundamentally solves the problem that traditional anti-corrosion layers, due to their low strength, cannot share the load under structural stress, merely increasing material weight without contributing to structural strength. This allows for a 10%–15% material thinning to achieve extreme lightweighting. Simultaneously, the use of spray deposition and multi-pass hot rolling technology eliminates interlayer oxide films and micro-gaps, constructing an atomically graded metallurgical bonding gradient region without interfacial thermal resistance. This ensures transient heat dissipation response under high heat flux density, thus achieving a comprehensive and synergistic breakthrough in high strength, high thermal conductivity, and long-life corrosion resistance for new energy vehicle radiator materials.

[0052] To achieve the core design concept of this invention, this fabrication process establishes an integrated technical route of in-situ endogenous strengthening—spray deposition composite—deformation densification control. This route abandons the traditional physical splicing mode of casting composite or brazing composite, and instead adopts a metallurgical fabrication framework based on atomic-level bonding. The basic framework of this fabrication process mainly consists of the following four continuous and logically related process stages:

[0053] A foundation for the smelting of the core alloy system was established. Through precise proportioning of the finished product, the solid solution properties of elements such as Mn, Cu, and Zr in the aluminum matrix were utilized to construct the material's basic strength and heat-resistant framework. Building upon this, in-situ reaction synthesis was introduced, where thermodynamically stable TiB2 nanoparticles were directly generated within the molten aluminum using salt reactions. This step differs from simple external particle stirring; it utilizes the heat released from the chemical reaction to purify the particle surface, fundamentally solving the problem of poor wettability between the reinforcing phase and the matrix, thus laying the material foundation for the subsequent preparation of a high-strength and tough core layer.

[0054] After obtaining the preheated core layer blank, an Al-Zn-Fe-Si-Mg-Sc-Zr surface melt is prepared in parallel. Unlike traditional liquid-liquid or solid-solid composite methods, this invention employs a deposition mode of semi-solid / liquid droplets impacting a solid substrate. High-pressure gas atomization technology breaks the surface melt into fine droplet streams, forming a high-energy particle beam. During this process, hydrophobically modified iron microparticles are precisely fed into the atomization cone, causing them to physically encapsulate or mechanically interlock with the flying droplets. The droplet stream carrying the iron microparticles then impacts the core layer surface at high speed, instantly breaking the natural oxide film on the substrate surface with enormous kinetic energy, achieving the spread, rapid solidification, and accumulation of droplets on the solid substrate. This process completes the initial physical bonding between the anti-corrosion layer and the core layer, forming a composite blank of a certain thickness.

[0055] Furthermore, since the spray-deposited layer is essentially an accumulation of countless micro-droplets, microscopic pores inevitably exist within it, and the deposition interface is still in a physically interlocked state. Therefore, densification must be achieved through thermomechanical processing. This preparation process employs a high-temperature, high-deformation hot rolling process. Under the combined action of heat and force, the pores in the deposition layer are forced to close, achieving full densification of the material. More importantly, by utilizing the atomic thermal motion at high temperatures, short-range interdiffusion of elements (such as Zn and Mn) at the core-to-surface interface is induced, eliminating the original deposition interface and forming a continuous crystal structure and compositional gradient transition zone. This stage marks a qualitative change in the material, from physical composite to metallurgical bonding.

[0056] Furthermore, while hot-rolled strips are dense, their strength is not yet at its maximum, and the dimensions require further precision. This manufacturing process introduces a high-density dislocation network and lattice distortion energy through cold rolling deformation with a high reduction rate. Subsequently, these stored energies are released using a finished product annealing process. A specific precipitation kinetic control step was designed for microalloying elements such as Sc and Zr. By controlling the heating rate and holding time, large-scale recrystallization (softening) of the matrix is ​​suppressed while inducing the dispersion precipitation of nano-reinforcing phases such as Al3(Sc, Zr) along dislocation lines. Through a series of deformation heat treatments, a high-strength precipitation-strengthened system is constructed in the anti-corrosion layer, and a micro-battery corrosion regulation mechanism is established around the surface iron particles, thereby obtaining a lightweight aluminum alloy composite material that meets design requirements.

[0057] The following section provides a detailed explanation and implementation guide for each step of this preparation process.

[0058] Step S1: Prepare the core layer melt, which includes aluminum, manganese, copper and zirconium.

[0059] It should be noted that the core melt, as the liquid aluminum alloy supporting the composite matrix, comprises the following components by mass percentage in this invention: manganese 1.2%–1.8%, copper 0.5%–1.0%, zirconium 0.1%–0.2%, titanium 0.05%–0.15%, boron 0.02%–0.06%, with the balance being aluminum and unavoidable impurities. Specifically:

[0060] Aluminum: The base element, using remelted aluminum ingots with a purity of not less than 99.7% to ensure excellent thermal conductivity and processing plasticity.

[0061] Manganese is a key element for improving the recrystallization temperature and high-temperature strength of aluminum alloys. In the melt, manganese atoms mix with aluminum atoms. During subsequent solidification, some manganese solidifies the matrix, while some forms Al6Mn or Al... 12 Mn2Cu dispersed phases can resist grain growth at high brazing temperatures, preventing the material from softening and sagging.

[0062] The main function of copper is solid solution strengthening and regulating the electrode potential of the core layer. Increasing the copper content will shift the core layer potential positively, thereby increasing the potential difference between the core layer and the anti-corrosion layer and enhancing the sacrificial anode protection effect.

[0063] Zirconium is key to the formation of the dispersed phase of Al3Zr. Al3Zr particles are extremely stable at high temperatures, pinning grain boundaries and subgrain boundaries, inhibiting recrystallization, and allowing the material to retain a fibrous structure after hot working, thereby significantly improving corrosion resistance and strength.

[0064] The preparation of the core melt in this step includes the following steps:

[0065] Step S11: Add aluminum ingots to the melting furnace and heat to 700℃-750℃ to completely melt them.

[0066] Step S12: Add Al-Mn, Al-Cu, and Al-Zr master alloys according to the specified ratio. Note that due to the high melting point of Zr, Al-5Zr or Al-10Zr master alloys must be used, and they should be added at a temperature above 750°C. Mechanical stirring should be used to ensure complete melting to prevent unmelted Zr particles from forming coarse inclusions later.

[0067] Step S2: Introduce reactive salts into the core layer melt to generate TiB2 nano-reinforcing particles through in-situ reaction. After casting and surface treatment, obtain the core layer billet and preheat it.

[0068] It should be noted that the reacting salt refers to a specific fluoride salt, preferably a mixed salt of potassium fluorotitanate (K2TiF6) and potassium fluoroborate (KBF4). In-situ reaction refers to the fact that the reinforcing particles are not directly added externally, but are generated within the matrix through a chemical reaction. The reaction equation is as follows: The TiB2 particles generated in situ have clean, uncontaminated surfaces and exhibit extremely strong interfacial bonding with the aluminum matrix, which is unmatched by externally added particles.

[0069] The method for generating TiB2 nanoparticles in this step includes the following steps:

[0070] In step S21, after the melt prepared in step S1 is heated to 750℃-800℃, the dried potassium fluorotitanate and potassium fluoroborate are added to the melt at a stoichiometric ratio of Ti:B atomic ratio of 1:2.

[0071] Step S22: While adding the reaction salt in step S21, electromagnetic stirring is performed at a frequency of 15Hz-35Hz and a power of 5kW-15kW for 15-30 minutes. After the reaction is completed, the reaction byproducts, namely fluoroaluminate slag, are removed from the surface.

[0072] During electromagnetic stirring, low-frequency stirring (<10Hz) mainly generates overall circulation and cannot break up agglomerates; high-frequency stirring (>50Hz) shows a significant skin effect but insufficient stirring in the core. However, stirring frequencies of 15Hz-35Hz can induce strong shear flow and micro-rheological effects inside the melt, using fluid shear force to break up the agglomerate chains of TiB2 particles in the early stages of formation, resulting in a dispersed distribution.

[0073] Specifically, the generated TiB2 particles possess high melting point, high hardness, and high modulus. In this step, the particle size is limited to 20 nm–100 nm and the mass fraction is controlled at 0.5%–2.0% by controlling the reaction conditions. These nanoparticles pin dislocations at grain boundaries, providing an Orowan strengthening mechanism.

[0074] After the in-situ reaction is complete, the core melt is introduced into a semi-continuous casting machine. The cooling water flow rate and casting speed must be matched to obtain a fine equiaxed grain structure. TiB2 particles act as heterogeneous nucleation sites during the casting process, significantly refining the ingot grains.

[0075] Furthermore, after the ingot cools, a milling machine is used to remove 2mm-5mm of the surface layer on both sides to remove the casting segregation layer, cold shut and oxide scale, exposing a clean matrix containing uniform TiB2 particles, which provides a physical basis for subsequent atomic-level bonding.

[0076] Furthermore, the milled core blank is fed into a heating furnace and preheated to 300℃-450℃. If the temperature is below 300℃, the deposited droplets solidify too quickly, resulting in poor wettability and weak interfacial bonding; if the temperature is above 450℃, the matrix is ​​too soft and is prone to deep pit deformation when impacted by droplets, and it is also prone to grain coarsening.

[0077] In step S3, a surface melt is prepared, which includes aluminum, zinc, magnesium, iron, silicon, scandium and zirconium.

[0078] It should be noted that the surface melt is a liquid aluminum alloy used to form the structural anti-corrosion layer, comprising the following components by mass percentage: zinc 1.0%–3.5%, magnesium 0.2%–0.8%, iron 0.15%–0.4%, silicon 0.1%–0.3%, scandium 0.15%–0.35%, zirconium 0.1%–0.2%, with the balance being aluminum and unavoidable impurities. Specifically:

[0079] Zinc is used to lower the potential, making the surface potential 80mV-150mV lower than the core potential, thus forming a sacrificial anode.

[0080] Magnesium and zinc work synergistically to enhance corrosion and improve corrosion morphology.

[0081] The ratio of iron to silicon (Fe:Si) is controlled between 1:1.5 and 1:2.5. At this ratio, Fe and Si form granular or skeletal α-AlFeSi phases, rather than long needle-like β-AlFeSi phases. This not only avoids fragmentation of the matrix and reduction of plasticity, but also provides microscopic hard particles, improving the wear resistance and strength of the anti-corrosion coating.

[0082] Scandium and zirconium are the core components that achieve high strength in the surface layer. The two are combined to form... Nano-precipitated phase. This phase has an L12-type structure, is coherent with the aluminum matrix, and has extremely high thermal stability and resistance to roughening. Through a strong pinning effect, the yield strength of the anti-corrosion layer is not less than 150 MPa, thus enabling it to work together with the core layer to bear the load and solve the strength dilution problem caused by traditional soft skin layers.

[0083] The melting process of the surface melt is similar to that of the core melt, with the melt temperature controlled between 720℃ and 780℃. Special attention must be paid to the method of adding scandium; an Al-2Sc master alloy is used, which is expensive, and a high yield must be ensured. Scandium and zirconium are added after refining and quickly stirred until homogeneous, minimizing their residence time in the furnace to prevent premature precipitation.

[0084] Step S4: Atomize the surface melt into droplets, inject surface-hydrophobic modified iron particles into the droplets in the atomization area, so that the droplets carrying iron particles are deposited on the surface of the core billet to form a composite billet.

[0085] It should be noted that this step employs supersonic jet deposition technology, with the atomizer utilizing a supersonic Laval nozzle structure. This nozzle accelerates the atomizing medium to supersonic speeds, generating enormous shear kinetic energy that breaks the surface melt into fine droplets with an average diameter of 20μm-80μm. These tiny droplets cool extremely rapidly, effectively suppressing the formation of coarse compounds on the surface and retaining Sc and Zr within the solid solution, laying the foundation for subsequent precipitation strengthening.

[0086] This step, regarding the hydrophobically modified iron microparticles and their injection process, specifically includes:

[0087] The hydrophobically modified iron microparticles have a particle size controlled between 1 μm and 10 μm. Each iron microparticle consists of a pure iron core and a thin layer of organosilane coupling agent coating its surface. The organosilane layer not only prevents the iron microparticles from oxidizing during high-temperature deposition but also reduces the wettability of corrosive media during subsequent service. The iron microparticles act as microcathodes in the anti-corrosion layer, inducing a uniform distribution of corrosion products and preventing localized pitting corrosion.

[0088] Furthermore, iron microparticles are delivered into the central low-pressure zone of the atomizing cone using a precision powder feeding device. Injection into this zone allows the surface tension of the droplets to capture the microparticles, encapsulating them within the semi-solid droplets or embedding them into the droplet surface, thus achieving uniform dispersion.

[0089] Specifically, the process parameters for jet deposition are controlled as follows:

[0090] The atomizing medium is high-purity nitrogen, with the pressure controlled between 0.8 MPa and 1.5 MPa. To prevent the formation of an oxide film that hinders bonding on the droplet surface, the dew point temperature of the nitrogen must be controlled below -60°C, and the oxygen content must be controlled below 5 ppm.

[0091] The deposition chamber is maintained at a slight negative pressure of -0.05MPa to -0.1MPa, and air is continuously pumped out to remove impurity gases.

[0092] The droplet stream carrying iron particles impacts the surface of the core layer blank after preheating in step S2 at a speed of not less than 150 m / s. The kinetic energy generated by the high-speed impact instantly breaks the trace oxide film on the substrate surface, enabling the droplets to spread and densely accumulate on the solid substrate.

[0093] Furthermore, by adjusting the moving speed of the core blank, the deposition thickness of the surface melt is strictly controlled, so that it accounts for 3% to 5% of the total thickness of the composite blank.

[0094] Step S5 involves heating and hot rolling the composite billet multiple times to form a metallurgical bonding interface between the core billet and the deposited layer.

[0095] It should be noted that the spray-deposited layer is essentially an accumulation of micro-droplets with internal micropores and the interfaces are still in a state of physical interlocking. The purpose of hot rolling is to close the pores through the action of heat and force, and to induce the diffusion of interfacial atoms to form a seamless metallurgical bond.

[0096] In this step, the hot rolling process employs a unique variable-temperature rolling method, specifically including the following steps:

[0097] Step S51: Send the composite billet into the heating furnace, set the temperature to 400℃-500℃, and keep it at that temperature for 2-6 hours to ensure uniform distribution of solute atoms.

[0098] Step S52: The initial pass is carried out in a high-temperature zone of 480℃-500℃, with the first pass reduction rate controlled at 15%-25%. Utilizing the high plasticity of aluminum alloy at this temperature, a significant reduction is achieved to close the pores of the deposited layer and promote atomic interdiffusion at the core-surface interface, forming a compositional gradient transition zone with a thickness of 5μm-20μm, thus eliminating interfacial thermal resistance.

[0099] Step S53: Subsequent passes gradually cool to 400℃-420℃ for rolling. Lower temperature plastic deformation allows for the accumulation of more dislocation density (work hardening), and these dislocation lines are crucial for subsequent rolling processes. Preferred nucleation sites. If high-temperature rolling is performed throughout the process, dislocations will disappear through dynamic recovery, leading to a decrease in the precipitation nucleation rate.

[0100] The total deformation during hot rolling must be no less than 80% to ensure full densification of the material.

[0101] Furthermore, at the hot rolling exit, a laminar flow cooling system is used to cool the strip, with the cooling rate controlled at 15℃ / s-30℃ / s. This rate can both prevent strip warping caused by quenching and suppress the segregation of solute atoms such as Mg, Zn, and Si at grain boundaries to form a continuous brittle network phase, thus ensuring the plasticity of the material in subsequent cold working.

[0102] Step S6: The hot-rolled strip is subjected to cold rolling deformation and finished product annealing to obtain aluminum alloy composite material.

[0103] It should be noted that this step is the finalization stage to obtain the final performance indicators. Lattice distortion energy is introduced through large deformation, and nanophase precipitation is induced through a specific annealing process.

[0104] In this step, the specific implementation of cold rolling and annealing is as follows:

[0105] Cold rolling deformation: carried out on a multi-roll cold rolling mill, with the total deformation controlled between 75% and 90%. The large deformation introduces an extremely high-density dislocation network, which is the driving force for the subsequent explosive nucleation of precipitates.

[0106] Finished product annealing: The cold-rolled strip is fed into an air-cushion continuous annealing furnace, and the annealing temperature is controlled at 280℃-350℃ for 1-10 minutes.

[0107] Specifically, the annealing heating process requires a "rapid heating process": the heating rate in the 200℃-280℃ range must be no less than 50℃ / s. Rapid passage through the low-temperature range can generate high-density GP regions or metastable phases, which serve as... The nucleation core of the composite nano-precipitate prevents the precipitate from being sparse and coarse, ultimately controlling the precipitate spacing to 50nm-150nm, achieving the best strengthening effect.

[0108] Furthermore, after the finished product is annealed, the cold-rolled strip undergoes a stretching and straightening process to control the elongation at 0.3% to 0.8%. This slight plastic deformation is used to eliminate residual thermal stress inside the strip, improve the flatness of the strip, and meet the requirements for automated forming of radiator fins.

[0109] The aluminum alloy composite material prepared by the above preparation process includes a high-strength core layer and a structural anti-corrosion layer metallurgically bonded to the surface of the high-strength core layer.

[0110] The high-strength core layer uses an Al-Mn-Cu-Zr alloy as the matrix, in which in-situ generated TiB2 nanoparticles are distributed. The TiB2 nanoparticles are located within the grains and at the grain boundaries, which not only refines the grains but also enables the core layer to maintain extremely high stiffness and fatigue resistance after thinning through dispersion strengthening and modulus strengthening mechanisms.

[0111] The structural anti-corrosion layer uses an Al-Zn-Fe-Si-Mg-Sc-Zr alloy as the matrix, with high-density [structures] distributed at the grain boundaries and within the grains. The composite nanophase enhances its yield strength to over 150 MPa, achieving a strength match with the high-strength core layer. Simultaneously, hydrophobically modified iron microparticles coated with a silane film are uniformly distributed within the matrix, serving as microcathode points to regulate corrosion.

[0112] Furthermore, there are no oxide interlayers or physical gaps between the high-strength core layer and the structural anti-corrosion layer, presenting a compositional gradient transition zone with a thickness of 5-20μm. This interface-free structure allows for smooth heat flow conduction, with almost zero interfacial thermal resistance, greatly improving heat dissipation efficiency.

[0113] The aluminum alloy composite material prepared by this invention has structural load-bearing capacity due to the structural anti-corrosion layer. It is no longer as weak as the traditional anti-corrosion layer, but has a certain strength. Moreover, the high-strength core layer is reinforced with TiB2 nanoparticles, which allows the total thickness of the material to be reduced by 10%-15% without reducing the overall structural strength.

[0114] Specifically, Zn and Mg form a negatively charged phase in the aluminum matrix, making the self-corrosion potential of the structural anti-corrosion layer lower than that of the high-strength core layer. The potential difference is controlled within the range of 80mV to 150mV, thereby providing electrochemical protection for the core layer through a sacrificial anode mechanism. Fe and Si form fine intermetallic compounds, which act as heterogeneous nuclei during deposition to promote grain refinement and synergistically enhance the initial hardness of the anti-corrosion layer.

[0115] Furthermore, the Sc and Zr in the structural anti-corrosion layer work together to form an L12-type structure with a particle size of 5nm-25nm. Composite nano-precipitates. The phase exhibits extremely high thermal stability and coherence with the matrix, enabling a significant increase in the yield strength of the structural anti-corrosion layer through a powerful pinning mechanism, ensuring that the yield strength of the structural anti-corrosion layer is not less than 150 MPa. This design transforms the anti-corrosion layer from a traditional non-load-bearing soft layer into a structurally integrated functional layer, allowing it to work in synergy with the high-strength core layer to share external loads. This eliminates the strength dilution effect of the composite material after thinning, achieving overall structural lightweighting.

[0116] The hydrophobic modified iron microparticles constitute 0.1%–0.5% of the structural anti-corrosion layer by mass. These microparticles consist of pure iron microparticles coated with a thin layer of organosilane coupling agent. The iron microparticles act as microcathodes within the anti-corrosion layer, inducing localized micro-cell reactions and resulting in a uniform distribution of corrosion products on the surface, thus preventing severe localized pitting corrosion. The organosilane coupling agent layer reduces the wettability of the liquid medium on the material surface during the initial stages of corrosion, thereby slowing the penetration rate of the corrosive medium into the material and significantly extending the CASS salt spray test life of this aluminum alloy composite material.

[0117] To further demonstrate the superiority of the technical solution of this invention, a comparative analysis is conducted below through specific embodiments, comparative examples, and experimental data.

[0118] Example 1:

[0119] The high-strength core layer composition is: Mn 1.5%, Cu 0.75%, Zr 0.15%, Ti 0.1%, B 0.04%, with the balance being Al; the mass fraction of TiB2 is 1.2%.

[0120] The structural anti-corrosion layer consists of: Zn 2.5%, Mg 0.5%, Fe 0.25%, Si 0.2%, Sc 0.25%, Zr 0.12%, with the balance being Al.

[0121] Key process parameters: electromagnetic stirring frequency 25Hz; spray deposition atomization pressure 1.2MPa; hot rolling first pass reduction rate 20%, first pass temperature 490℃; total cold rolling deformation 85%; finished product annealing temperature 320℃. Hydrophobic modified iron microparticles added 0.3%.

[0122] Example 2:

[0123] The high-strength core layer composition is: Mn 1.8%, Cu 0.6%, Zr 0.15%, Ti 0.1%, B 0.04%, with the balance being Al; the mass fraction of TiB2 is 1.8%.

[0124] The structural anti-corrosion layer consists of: Zn 3.0%, Mg 0.5%, Fe 0.25%, Si 0.2%, Sc 0.3%, Zr 0.12%, with the balance being Al.

[0125] Key process parameters: electromagnetic stirring frequency 25Hz; spray deposition atomization pressure 1.5MPa; hot rolling first pass reduction rate 20%, first pass temperature 490℃; cold rolling total deformation 85%; finished product annealing temperature 300℃. Hydrophobic modified iron microparticles added 0.3%.

[0126] Example 3:

[0127] Based on Example 2, the only difference is that the electromagnetic stirring frequency during the in-situ reaction in step S2 is set to 5Hz.

[0128] Example 4:

[0129] Based on Example 2, the only difference is that the electromagnetic stirring frequency during the in-situ reaction in step S2 is set to 60Hz.

[0130] Example 5:

[0131] Based on Example 2, the only difference is that the temperature of the initial hot rolling pass in step S5 is set to 400°C.

[0132] Example 6:

[0133] Based on Example 2, the only difference is that the temperature of the initial hot rolling pass in step S5 is set to 550°C.

[0134] Example 7:

[0135] Based on Example 2, the only difference is that the content of Sc in the structural anti-corrosion layer is 0.05%.

[0136] Example 8:

[0137] Based on Example 2, the only difference is that the content of Sc in the structural anti-corrosion layer is 0.6%.

[0138] Comparative Example 1:

[0139] The core layer uses traditional 3003 aluminum alloy (excluding TiB2 and high content of Cu and Zr), and the anti-corrosion layer uses conventional 7072 alloy. The manufacturing process uses traditional hot-rolled aluminum cladding composite process, rather than spray deposition.

[0140] Comparative Example 2:

[0141] The alloy composition of the core layer and the anti-corrosion layer is completely consistent with that of Example 1.

[0142] Instead of using spray deposition, the preparation process involves casting the core layer and anti-corrosion layer ingots separately, followed by milling and then using traditional hot-pressing and rolling composite processes.

[0143] The finished strips prepared in the above embodiments and comparative examples, with a thickness of 0.2 mm, were subjected to performance tests: Standard tensile specimens were prepared according to GB / T228.1-2010 standard, and the tensile strength (Rm), yield strength (Rp0.2), and elongation after fracture (A) were measured. The thermal diffusivity was determined using the laser flare method, the thermal conductivity was calculated, and the interfacial thermal resistance was determined using the steady-state heat flow method.

[0144] The CASS test was conducted according to ASTM B368 standard, with a test duration of 168 hours. After the test, the sample surface was cleaned, and the number of isolated corrosion spots visible to the naked eye on the sample surface was counted, defined as deep pit-like defects with a diameter > 0.5 mm. The performance comparison test data are summarized in Table 1 below.

[0145] Table 1. Summary of Experimental Data

[0146]

[0147] Furthermore, for Examples 1 and 2 and Comparative Examples 1 and 2, cross-sections of the samples were taken after the CASS test. The depth and opening width of the first five deepest corrosion pits were measured using a laser confocal microscope, and the average depth / opening width ratio was calculated. The surface of the anti-corrosion layer was scanned using scanning Kelvin probe technology, with a scanning area of ​​5 mm × 5 mm. Voltaic potential data were recorded and variance calculated. The core layer / anti-corrosion layer interface was observed using a transmission electron microscope, and the percentage of the length without continuous amorphous oxide layer coverage on the interface line within the field of view was statistically analyzed. The microscopic mechanism verification data are summarized in Table 2.

[0148] Table 2. Microscopic Mechanism Verification Data

[0149]

[0150] As can be seen from the data in Tables 1 and 2, Examples 1 and 2 have achieved fundamental breakthroughs over the prior art in terms of strength, interfacial bonding, and corrosion resistance mechanism.

[0151] Traditionally, the introduction of iron is often considered a trigger for pitting corrosion in aluminum alloys. However, the measured data in Table 1 show that after 168 hours of rigorous CASS testing, Examples 1 and 2 exhibited only 2-3 isolated corrosion pits on their surfaces, demonstrating excellent resistance to localized corrosion. In contrast, Comparative Example 1, which used a conventional composite process, showed 18 obvious isolated corrosion pits with significant depth; even Comparative Example 2, which used the same alloy composition but did not undergo microparticle injection, showed 12 isolated corrosion pits on its surface.

[0152] This significant difference is reasonably explained by the micro-indicator data in Table 2:

[0153] The corrosion pit depth-to-diameter ratio of Example 1 is only 0.18, indicating that the corrosion is mainly characterized by wide and shallow layered erosion, a form that is extremely difficult to penetrate thin-walled radiators. In contrast, the corrosion pit depth-to-diameter ratio of Comparative Example 1 is as high as 0.82, exhibiting typical deep longitudinal pit characteristics. This is the main reason for the large number and conspicuousness of isolated corrosion points.

[0154] The surface potential variance in Example 1 was significantly lower than that in Comparative Example 1. This confirms that the present invention, through a synergistic strategy of hydrophobic modification and dispersion injection, successfully transformed iron microparticles from pitting corrosion sources into current dispersants, effectively suppressing the intensity of local electrochemical reactions.

[0155] The interfacial thermal resistance of Examples 1 and 2 is extremely low, significantly better than that of the comparative examples. The interfacial oxide film breakage rate in Table 2 reveals its physical nature: the oxide film breakage rate of Example 1 is as high as 96.5%, while that of Comparative Example 2, which did not have solid particles injected, is only 78.5%. This confirms that the solid iron particles injected in step S4 of this invention significantly enhance the mechanical breakage effect on the oxide film on the substrate surface during deposition. Compared to liquid droplets, these solid hard particles embedded in the jet, when impacting the surface of the high-strength core layer, utilize their high hardness and momentum transfer efficiency to generate a strong local impact shearing effect, effectively breaking and dispersing the dense oxide film, thereby eliminating physical barriers at the interface and achieving truly unobstructed atomic-level diffusion in subsequent hot rolling.

[0156] In Examples 3 and 4, the TiB2 distribution was poor due to improper stirring frequency. Although the strength decreased, the number of isolated corrosion spots was controlled at 6-7 thanks to the preservation of the surface iron microparticle mechanism, which was still better than the comparative example. In Example 7, the insufficient Sc content resulted in low strength of the anti-corrosion layer matrix and weak resistance during corrosion, leading to an increase in the number of corrosion spots to 9. This indicates a synergistic effect between matrix strengthening and the microparticle anti-corrosion mechanism.

[0157] Furthermore, the aluminum alloy composite material and its preparation process for a lightweight new energy vehicle radiator described in this invention adopt a dual strategy of equal-strength substitution and thinning for increased efficiency in achieving lightweighting. Because the structural anti-corrosion layer itself possesses a yield strength of no less than 150 MPa, designers can fully incorporate the thickness of the anti-corrosion layer into the effective load-bearing thickness when performing structural mechanical calculations for the radiator. This is fundamentally different from the traditional design approach that only considers the core layer as a load-bearing component. Under this design logic, the wall thickness of the radiator pipe can be reduced from the traditional 0.25 mm to 0.18 mm to 0.20 mm, while the overall structural compressive strength and burst pressure resistance remain above safe limits.

[0158] In summary, this invention, through precise design of the core / anti-corrosion layer composition, combined with the organic integration of in-situ reaction, jet deposition injection, and refined thermal processing, successfully prepared an aluminum alloy composite material possessing high strength, high thermal conductivity, and high corrosion resistance. There is a close synergistic effect among the various process steps and parameter ranges; none can be omitted, perfectly solving the technical challenges faced in lightweighting radiators for new energy vehicles.

[0159] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A preparation process for an aluminum alloy composite material for a lightweight new energy vehicle radiator, characterized in that, Includes the following steps: S1. Prepare the core layer melt, wherein the core layer melt comprises aluminum, manganese, copper and zirconium; S2. Introduce reactive salts into the core layer melt to generate TiB2 nano-reinforcing particles through in-situ reaction. After casting and surface treatment, obtain the core layer blank and preheat the core layer blank. S3. Prepare a surface melt, wherein the surface melt comprises aluminum, zinc, magnesium, iron, silicon, scandium, and zirconium; S4. The surface melt is atomized into droplet streams, and iron microparticles modified with hydrophobic properties are injected into the droplet streams in the atomization area, so that the droplet streams carrying iron microparticles are deposited on the surface of the core layer billet to form a composite billet. S5. The composite billet is heated and hot-rolled in multiple passes to form a metallurgical bonding interface between the core billet and the deposited layer. S6. The hot-rolled strip is subjected to cold rolling deformation and finished product annealing to obtain aluminum alloy composite material.

2. The preparation process of the aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, The core melt comprises the following components by mass percentage: 1.2%–1.8% manganese, 0.5%–1.0% copper, 0.1%–0.2% zirconium, 0.05%–0.15% titanium, 0.02%–0.06% boron, with the balance being aluminum and unavoidable impurities.

3. The preparation process of the aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, The surface melt comprises the following components by mass percentage: zinc 1.0%–3.5%, magnesium 0.2%–0.8%, iron 0.15%–0.4%, silicon 0.1%–0.3%, scandium 0.15%–0.35%, zirconium 0.1%–0.2%, with the balance being aluminum and unavoidable impurities.

4. The preparation process of the aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, In step S2, the specific method for generating TiB2 nano-reinforced particles in situ is as follows: the core layer melt is heated to 750℃-800℃, dried potassium fluorotitanate and potassium fluoroborate are added, and electromagnetic stirring is applied at the same time as the addition. The electromagnetic stirring frequency is 15Hz-35Hz, the power is 5kW-15kW, and the continuous reaction time is 15-30min.

5. The preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, The preheating refers to preheating the surface-treated core layer blank to 300℃-450℃.

6. The preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, In step S4, the iron microparticles modified with hydrophobic surface have a particle size of 1μm-10μm and are composed of a pure iron core and a thin layer of organosilane coupling agent coated on its surface. The injection process is as follows: the iron microparticles are fed into the low-pressure zone at the center of the atomizing cone by a powder feeding device, and the microparticles are captured by the surface tension of the droplets.

7. The preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, In step S4, the process parameters for surface melt atomization and deposition include: The atomizing medium is high-purity nitrogen, the atomization pressure is 0.8MPa-1.5MPa, the dew point temperature of nitrogen is controlled below -60℃, and the oxygen content is controlled below 5ppm. The deposition chamber pressure was maintained between -0.05 MPa and -0.1 MPa. The velocity of the liquid droplets carrying iron particles impacting the surface of the core layer blank is ≥150m / s; The deposition thickness of the surface melt is controlled to be 3% to 5% of the total thickness of the composite billet.

8. The preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, In step S5, the multi-pass hot rolling adopts a variable temperature rolling process, specifically including: Heat the composite preform to 400℃-500℃ and hold for 2-6 hours; The initial passes are conducted at 480℃-500℃, with a reduction rate of 15%-25% in the first pass. Subsequent passes will be conducted at 400℃-420℃. The total deformation during hot rolling is ≥80%; and after hot rolling, the strip is subjected to laminar flow cooling at a rate of 15℃ / s-30℃ / s.

9. The preparation process of an aluminum alloy composite material for a lightweight new energy vehicle radiator according to claim 1, characterized in that, In step S6, the total deformation amount of the cold rolling deformation is 75% to 90%. The method for annealing the finished product is as follows: the cold-rolled strip is fed into an annealing furnace, the annealing temperature is 280℃-350℃, and the holding time is 1-10min; wherein, the heating rate in the annealing heating stage in the range of 200℃-280℃ is not less than 50℃ / s.

10. An aluminum alloy composite material, characterized in that, It is prepared using the aluminum alloy composite material of a lightweight new energy vehicle radiator according to any one of claims 1-9.

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