Aluminum alloy composite material and method for manufacturing the same

Abstract

The application relates to an aluminum alloy composite material, which comprises a core material layer, at least one intermediate layer and an optional brazing layer, the core material layer comprising Si, Fe, Cu, Mg, Mn, Ni, Zn, Al and one, two or three of Cr, Ti and Zr, wherein the content of Si is 0.1-0.6% by weight, the content of Fe is 0.2-0.7% by weight, the total content of Cu and Mg is 1.2-3.3% by weight, and the weight ratio of Cu to Mg is 0.6-5; the total content of Cu and Mn is 1.2-3.3% by weight, and the weight ratio of Cu to Mn is 1-3; the content of Ni is 0.03-0.5% by weight; the content of Zn is 0.05-0.5% by weight; the content of each of Cr, Ti and Zr is less than 0.05% by weight, and the total content of Cr, Ti and Zr is less than 0.1% by weight, and wherein the number density of dispersed phases in the core material layer after brazing is 1x10 4 -5x10 4 mm-3 2 . The aluminum alloy composite material has excellent mechanical properties and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and in particular to a multilayer aluminum alloy composite material that can be used for brazing and its preparation method. Background Technology

[0002] To meet the demands of new energy vehicle development, the energy density and power density of power batteries are increasing, leading to greater heat generation. Water cooling has become the mainstream method for power battery heat dissipation, and the development of high-efficiency water-cooled plates has become a key focus of battery pack integration design. Conventional battery water-cooled plates consist of a substrate and a flow channel plate brazed at high temperatures to form coolant channels for battery heat dissipation. With the development of integrated design, water-cooled plates, in addition to heat dissipation, must also provide structural support for the battery pack. However, due to the low mechanical properties of conventional water-cooled plate materials after high-temperature brazing, they cannot effectively support the battery.

[0003] Composite plates for aluminum alloy brazing are typically composed of two or more layers of aluminum alloy, with AA3003 or AA3003mod aluminum alloy as the core material and Al-Si alloy as the brazing filler layer. The AA3003 or AA3003mod core material provides the composite material with properties such as strength and corrosion resistance after brazing. However, AA3003 or AA3003mod aluminum alloy is a non-heat-treatable strengthening alloy. Even after high-temperature brazing and modification, the yield strength of AA3003mod alloy is generally below 60 MPa, and the tensile strength is generally below 160 MPa, which does not meet the strength requirements of next-generation battery water-cooling plates.

[0004] CN115427188A relates to a brazable Al-Mg-Si aluminum alloy, wherein brazing is performed at a relatively low cooling rate and artificial aging is required to improve strength. CN114752829A relates to a brazable Al-Mg-Si aluminum alloy in which a certain amount of Mn and Cr are added to the core material to control the precipitation and distribution of the strengthening phase Mg2Si. After brazing, artificial aging is performed after air cooling or wind cooling to obtain a higher yield strength. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a high-strength aluminum alloy composite material for brazing, its preparation method, and brazed aluminum alloy components and heat exchangers made therefrom. This aluminum alloy material is suitable for controlled atmosphere brazing processes, can be used as sheet metal, and is insensitive to post-brazing cooling rates. It exhibits high post-brazing strength without requiring additional artificial aging treatment and possesses excellent corrosion resistance.

[0006] In one aspect, the present invention relates to an aluminum alloy composite material comprising: a core layer and at least one intermediate layer. The core layer comprises one, two, or three of the following: Si, Fe, Cu, Mg, Mn, Ni, Zn, Al, and Cr, Ti, and Zr. Based on the total weight of the core layer, the content of Si is 0.1 to 0.6 wt%; the content of Fe is 0.2 to 0.7 wt%; the total content of Cu and Mg is 1.2 to 3.3 wt%, and the weight ratio of Cu to Mg is 0.6 to 5; the total content of Cu and Mn is 1.2 to 3.3 wt%, and the weight ratio of Cu to Mn is 1 to 3; the content of Ni is 0.03 to 0.5 wt%; the content of Zn is 0.05 to 0.5 wt%; and the content of each of Cr, Ti, and Zr is less than 0.05 wt%, with a total content of less than 0.1 wt%. After brazing, the number density of the dispersed phase in the core layer is 1 × 10⁻⁶. 4 Up to 5×10 4 pcs / mm 2 .

[0007] In another aspect, the present invention relates to a method for preparing an aluminum alloy composite material, comprising: providing a core layer, an intermediate layer and optionally a brazing layer; heat-treating the core layer and the intermediate layer respectively; alloying the core layer, the intermediate layer and optionally the brazing layer to obtain a composite; heat-treating the composite and then rolling it to a target thickness; and annealing.

[0008] In another aspect, the present invention relates to a method for preparing aluminum alloy brazed parts, comprising: providing the aluminum alloy composite material of the present invention; brazing; and placing the brazed material at room temperature for natural aging treatment. Attached Figure Description

[0009] Figure 1a The material delivery state (O state) of Embodiment 1 of the present invention is shown as a tissue particle.

[0010] Figure 1b The microstructure of the material after brazing according to Embodiment 1 of the present invention is shown.

[0011] Figure 2a A photograph of the grain structure of the material in the delivery state (O state) of Embodiment 1 of the present invention is shown.

[0012] Figure 2b A photograph of the grain structure of the material after brazing according to Embodiment 1 of the present invention is shown.

[0013] Figure 3a A schematic diagram of the three-layer structure of the multilayer aluminum alloy composite material of the present invention is shown.

[0014] Figure 3b A schematic diagram of the four-layer structure of the multilayer aluminum alloy composite material of the present invention is shown.

[0015] Figure 3c A schematic diagram of the five-layer structure of the multilayer aluminum alloy composite material of the present invention is shown. Detailed Implementation

[0016] General definitions and terms

[0017] Unless otherwise stated, all publications, patent applications, patents and other references mentioned herein are incorporated herein in their entirety by way of citation.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of any conflict, the definitions provided herein shall prevail. Unless otherwise stated, all percentages, parts, proportions, etc., are by weight.

[0019] When a quantity, concentration, or other value or parameter is given as a range, preferred range, or preferred upper and lower limits, or a specific value, it should be understood as specifically disclosing all ranges formed by pairs of values ​​from any upper or preferred range and any lower or preferred range, regardless of whether the range is disclosed individually. Unless otherwise stated, when a numerical range is referred to herein, the range means including its endpoints and all integers and fractions within that range. The scope of this invention is not limited to the specific numerical value referenced when defining a range. For example, "1-8" encompasses 1, 2, 3, 4, 5, 6, 7, 8, and any subrange consisting of any two values ​​therein, such as 2-6, 3-5, etc.

[0020] The terms “comprising,” “including,” “having,” “containing,” or “involving,” and their other variations herein, are inclusive or open-ended and do not exclude other unlisted elements or method steps. Those skilled in the art will understand that the foregoing terms such as “comprising” encompass the meaning of “consisting of.” The expression “consisting of” excludes any unspecified elements, steps, or ingredients. The expression “substantially constitutes” limits the scope to the specified elements, steps, or ingredients, plus optional elements, steps, or ingredients that do not materially affect the essential and novel features of the claimed subject matter. It should be understood that the expression “comprising” encompasses both the expressions “substantially constitutes” and “consisting of.”

[0021] The term “selected from…” means one or more elements from the groups listed below, selected independently, and may include combinations of two or more elements.

[0022] When describing numerical or range endpoints in this document, it should be understood that the disclosure includes the specific values ​​or endpoints referenced.

[0023] As used herein, the terms “one or more” or “at least one” refer to one, two, three, four, five, six, seven, eight, nine or more.

[0024] Unless otherwise stated, the terms "combination thereof" and "mixture thereof" refer to a multi-component mixture of the elements, such as two, three, four, and up to the maximum possible multi-component mixture.

[0025] Furthermore, if the number of components or parts of the present invention is not previously specified, it indicates that there is no limitation on the number of times a component or part may appear (or be present). Therefore, it should be interpreted as including one or at least one, and the singular form of a component or part also includes the plural, unless the value clearly indicates a singular number.

[0026] As used herein, the terms “optional” or “optionally” mean that the event or situation subsequently described may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0027] As used in this article, the term "surface" refers to the interface between an object and the external environment, which typically has no thickness, such as the interface between a composite material and the external environment. Its shape usually depends on the shape of the object, and can be a planar or curved structure.

[0028] As used in this article, the term "surface layer" refers to a portion of an object located at a certain distance from its surface, typically possessing a certain thickness. For example, in composite materials, this refers to a portion of the material located at a certain distance from its surface (e.g., within a few micrometers, tens of micrometers, or hundreds of micrometers) and possessing a certain thickness. Its shape is usually related to the shape of the object, and may be a planar plate or a curved strip.

[0029] The term "composite ratio" used in this article refers to the proportion of the thickness of each layer to the total thickness of the composite material. Taking the core layer as an example, the core layer composite ratio is the proportion of the core layer thickness to the total thickness of the multilayer composite material.

[0030] As used in this article, "artificial aging" refers to a heat treatment process in which a metallic material, such as a heat-treatable aluminum alloy, is held at a high temperature for a period of time, for example, at 100 °C or higher for more than one hour, after solution treatment or equivalent solution treatment, to accelerate the precipitation of strengthening phases and improve strength and hardness. The temperature and holding time of artificial aging depend on factors such as the type, composition, thickness, and performance objectives of the metallic material.

[0031] The term "natural aging" as used in this article refers to the phenomenon and process by which a metallic material undergoes spontaneous microstructural evolution over time under room temperature or near-room temperature conditions after solution treatment or equivalent solution treatment, resulting in a gradual increase in strength and hardness.

[0032] As used in this paper, the term "cubic texture" refers to a grain with a crystallographic orientation of {100}. <001> That is, the {100} crystal plane of the grain is parallel to the rolling plane of the plate, and the grain's <001> The crystal orientation is parallel to the rolling direction of the plate.

[0033] The term “Cube” used in this article ND "Texture," also known as "rotational cubic texture" or "normal cubic texture," refers to the crystallographic orientation of a grain as {100}. <310> That is, the {100} crystal plane of the grain is parallel to the rolling plane of the plate, and the grain's <310> The crystal orientation is parallel to the rolling direction of the plate.

[0034] The term "texture proportion" as used in this article refers to a certain type of texture, such as Cube texture or Cube ND The percentage of the area covered by texture relative to the total area tested in the material. Data on the texture percentage can be obtained, for example, through electron backscatter diffraction (EBSD) testing.

[0035] As used herein, the term "AA4XXX series alloys" is a commonly used alloy designation in the art, well-known to those skilled in the art, such as in GB-T 3190-2016 Chemical Composition of Wrought Aluminum and Aluminum Alloys. AA4XXX series alloys are a series of alloys with aluminum and silicon as the main elements. For example, the 4XXX alloys mentioned herein include, but are not limited to, 4343 aluminum alloy (AA4343) and 4045 aluminum alloy (AA4045).

[0036] The term "new energy vehicle" as used in this article refers to automobiles that rely entirely or partially on electricity as their power source. Examples include, but are not limited to, battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), range-extended electric vehicles (EREVs), and fuel cell electric vehicles (FCEVs).

[0037] Aluminum alloy composite materials

[0038] The present invention relates to an aluminum alloy composite material comprising: a core layer, at least one intermediate layer, and an optional brazing layer.

[0039] In one embodiment, the aluminum alloy composite material of the present invention comprises a core layer and two intermediate layers. For example... Figure 3a As shown, the two intermediate layers are located on both sides of the core material layer.

[0040] In one embodiment, the aluminum alloy composite material of the present invention comprises a core layer, two intermediate layers, and a brazing layer. For example... Figure 3b As shown, the two intermediate layers are located on both sides of the core layer, and the brazing layer is located on the side of either intermediate layer away from the core layer.

[0041] In one embodiment, the aluminum alloy composite material of the present invention comprises a core layer, two intermediate layers, and two brazing layers. For example... Figure 3c As shown, the two intermediate layers are located on both sides of the core layer, and the two brazing layers are located on the side of the two intermediate layers away from the core layer.

[0042] The aluminum alloy composite material of the present invention has a multi-layer structure, and the thickness of each layer depends on its main function in practical applications. The thickness of the aluminum alloy composite material is related to the number of layers, and the thickness of each layer also needs to be considered for further adjustment.

[0043] The overall thickness of the aluminum alloy composite material of the present invention can be 0.5 to 2 mm, preferably 0.7 to 1.8 mm, for example 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 mm, and any range consisting of any two of these values. The thickness of each layer can be adjusted within a reasonable range according to actual needs.

[0044] The aluminum alloy composite material of the present invention can obtain excellent mechanical properties and corrosion resistance without artificial aging treatment. Therefore, in one embodiment, the aluminum alloy composite material is not artificially aged after brazing.

[0045] Core layer

[0046] The core layer is one of the main structural components of aluminum alloy composites, and its properties (such as hardness, strength, and toughness) affect the composite material. The core layer provides support and is also the main source of the material's post-weld strength.

[0047] The thickness of the core layer is affected by the number of material layers and can be selected according to actual needs. Generally, the composite ratio of the core layer can be from 50% to 95%, for example, 50%, 55%, 60%, 61%, 62%, 63%, 64%, 65%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 90%, 95%, and any two of these values, to ensure that the final composite material obtains suitable properties (such as hardness, strength, and resistance to deformation).

[0048] In this document, the core layer refers to the alloy material used to prepare the core layer, and may also be referred to as the raw material of the core layer, the raw material alloy of the core layer, etc. It is understood that during the preparation of composite materials, factors such as heat treatment and equipment contact may cause element diffusion, leading to a certain difference between the actual composition of the core layer and the core layer composition. Under the usual preparation conditions in the art, starting from the core layer of this application, the desired actual composition can be assigned to the core layer, thereby ensuring that the composite material has excellent performance. In one embodiment, in the multilayer aluminum alloy composite material obtained by the preparation method described below, the raw material of the core layer is the core layer alloy described in this application, and the core layer has the desired actual composition.

[0049] As a layer with a high composite ratio in composite materials, the core layer usually has a critical impact on the performance of the composite material. Through the rational design of the core layer, the properties of multilayer aluminum alloy composite materials, especially mechanical properties and corrosion resistance, can be effectively improved and optimized.

[0050] The types and contents of elements in the core layer alloy are important factors affecting the performance of the core layer, because the types and contents of elements will affect the types and contents of compounds formed between elements, which in turn will affect the material properties.

[0051] The inventors discovered that when aluminum alloy materials containing a combination of Cu, Mg, and Mn are used as core layer alloys, by further controlling the specific content of each element to obtain a specific composition, the mechanical properties and corrosion resistance of the core layer can be effectively improved simultaneously. This enables the composite material and its products to meet the higher requirements for strength and corrosion resistance in current practical applications.

[0052] In one embodiment, the core layer of the aluminum alloy composite material of the present invention comprises one, two, or three of Si, Fe, Cu, Mg, Mn, Ni, Zn, Al, Cr, Ti, and Zr.

[0053] The presence of silicon (Si) in the core layer affects its strength and corrosion resistance. Si promotes the precipitation of manganese (Mn) from the solid solution, resulting in a high-density dispersed AlMnSi particle phase, thus improving the strength of the composite material. Furthermore, when the alloy contains both Cu and Mg, the combination of Mg and Si precipitates Mg₂Si nanoparticles, enhancing the alloy's strength. Similarly, the combination of Mg and Cu precipitates AlCuMg nanoparticles, also improving strength. However, the strengthening effect of Mg₂Si particles is weaker than that of AlCuMg. If the Si content in the core layer is too low, it will negatively impact the product's strength; conversely, if the Si content is too high, the material's corrosion resistance will significantly deteriorate. Therefore, controlling the amount of Si added to the core layer is crucial for achieving good strength and corrosion resistance.

[0054] In one embodiment, based on the total weight of the core layer, the Si content in the core layer can be 0.1 to 0.6% by weight, preferably 0.15 to 0.5% by weight, for example, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31%. 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6% by weight, and a range consisting of any two of these values.

[0055] Fe in the core layer can combine with other elements, such as Mn and Si, to form casting crystalline phases. These crystalline phases can become intermetallic compounds with recrystallization nuclei, thus lowering the recrystallization temperature. Excessive Fe content may reduce the corrosion resistance and strength of the composite material. Therefore, it is necessary to control the Fe content in the core layer within an appropriate range.

[0056] In one embodiment, based on the total weight of the core layer, the Fe content in the core layer can be 0.2 to 0.7% by weight, preferably 0.3 to 0.6% by weight, for example, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41%. 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7% by weight, and a range consisting of any two of these values.

[0057] Cu in the core layer provides solid solution strengthening. When the Cu content exceeds a certain level (e.g., 0.8%), the dissolved Cu precipitates as fine Al₂Cu particles at low temperatures, resulting in a certain degree of age-hardening. However, Cu tends to precipitate at grain boundaries, increasing the risk of intergranular corrosion. If the Cu content in the core layer is too low, the age-hardening benefits are not significant; if the Cu content is too high, the likelihood of intergranular corrosion increases. Therefore, it is necessary to control the Cu content in the core layer within a suitable range.

[0058] In one embodiment, based on the total weight of the core layer, the Cu content in the core layer can be from 0.8 to 1.8 wt%, preferably from 0.9 to 1.7 wt%, for example, 0.8, 0.9, 0.98, 1, 1.1, 1.2, 1.24, 1.3, 1.4, 1.5, 1.52, 1.6, 1.68, 1.7, 1.8 wt%, and a range consisting of any two of these values.

[0059] Mg in the core layer can significantly improve the strength of the alloy. On one hand, Mg can enhance strength through solid solution strengthening. On the other hand, Mg combining with Si precipitates Mg₂Si nanoparticles, further increasing strength; Mg combining with Cu precipitates AlCuMg nanoparticles, also enhancing strength, and exhibiting age-hardening capabilities. Controlling the relative ratio of Mg to Cu content is crucial for managing their interactions. When the Mg content is too low, the technical effect is weak. When the Mg content is too high, Mg may diffuse during brazing, adversely affecting the flux activity and leading to poor brazing results; excessive Mg content also easily leads to grain boundary corrosion. Therefore, it is necessary to control the Mg content and the relative ratio of Mg to Cu in the core layer.

[0060] In one embodiment, based on the total weight of the core layer, the total amount of Cu and Mg in the core layer is 1.2 to 3.3% by weight, preferably 1.8 to 3% by weight, for example, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.98, 2, 2.07, 2.1, 2.11, 2.2, 2.23, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3% by weight, and a range consisting of any two of these values, and wherein the weight ratio of Cu to Mg is 0.6 to 5, preferably 0.8 to 3.5, more preferably 1. Up to 3, for example, 0.6, 0.7, 0.8, 0.87, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.67, 1.7, 1.8, 1.9, 2, 2.1, 2.16, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.05, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, and a range consisting of any two of these values.

[0061] In one embodiment, based on the total weight of the core layer, the Mg content in the core layer can be from 0.4 to 1.5% by weight, preferably from 0.6 to 1.3% by weight, for example, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.74, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.13, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5% by weight, and a range consisting of any two of these values.

[0062] Including an appropriate amount of manganese (Mn) in the core layer helps improve the material's strength, brazability, corrosion resistance, and potential. In aluminum alloys, Mn forms AlMnFe and AlMnFeSi crystalline phases with Fe and Si, which reduce the adverse effects of Fe on the strength and corrosion resistance of the aluminum alloy. Furthermore, dissolved Mn in the aluminum alloy forms a large amount of AlMn or AlMnSi dispersed phases. The formation of these dispersed phases promotes the precipitation and uniform distribution of other strengthening phases, which is beneficial for improving material strength. When Cu is also present, Mn and Cu combine to form AlMnCu-type dispersed phases. However, the precipitation of AlMnCu-type dispersed phase particles consumes Cu, thus affecting the material's strength. Therefore, it is necessary to control the Mn content and the ratio of Mn to Cu in the core layer.

[0063] In one embodiment, based on the total weight of the core layer, the total amount of Cu and Mn in the core layer is 1.2 to 3.3% by weight, preferably 1.6 to 3% by weight, for example, 1.2, 1.4, 1.5, 1.6, 1.7, 1.8, 1.83, 1.88, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.77, 2.8, 2.83, 2.9, 3, 3.1, 3.2, 3.3% by weight, and composed of... The range consisting of any two values, wherein the weight ratio of Cu to Mn is 0.8 to 3, preferably 1 to 3, for example 0.8, 0.9, 1, 1.09, 1.1, 1.16, 1.2, 1.3, 1.4, 1.5, 1.54, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, and the range consisting of any two values.

[0064] In one embodiment, based on the total weight of the core layer, the Mn content in the core layer can be from 0.4 to 1.5% by weight, preferably from 0.55 to 1.4% by weight, for example, 0.4, 0.45, 0.5, 0.55, 0.59, 0.6, 0.65, 0.7, 0.74, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.09, 1.1, 1.13, 1.15, 1.2, 1.25, 1.3, 1.31, 1.35, 1.4, 1.45, 1.5% by weight, and a range consisting of any two of these values.

[0065] Adding Ni to the core layer can form uniform Al3Ni particles, which can improve the heat resistance of the alloy. When Cu is present, Ni and Cu can form the Al7Cu4Ni phase; when Fe is present, the combination of Ni and Fe can form Al9FeNi. Once these phases are formed, they will not change during subsequent hot working processes, exhibiting good thermal stability and improving the heat resistance of the core material.

[0066] In one embodiment, based on the total weight of the core layer, the Ni content in the core layer can be from 0.03 to 0.5% by weight, preferably from 0.05 to 0.3% by weight, for example, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, ... 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5% by weight, and a range consisting of any two of these values.

[0067] Adding Zn to the core alloy reduces the electrode potential of Al and inhibits localized corrosion. Adding Zn to Cu-containing alloys neutralizes the precipitation of Cu particles, reducing their precipitation at grain boundaries and thus decreasing the tendency for intergranular corrosion in the core alloy.

[0068] In one embodiment, based on the total weight of the core layer, the Zn content in the core layer can be 0.05 to 0.5% by weight, preferably 0.06 to 0.45% by weight, for example, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5% by weight, and a range consisting of any two of these values.

[0069] Cr can form intermetallic compounds such as AlCrFe and AlMnCr in Al-containing alloys, hindering the nucleation and growth processes of recrystallization, but increasing quenching sensitivity. Therefore, the Cr content needs to be strictly controlled.

[0070] In one embodiment, based on the total weight of the core layer, the Cr content in the core layer is ≤0.05% by weight, preferably ≤0.025% by weight, for example ≤0.05, ≤0.045, ≤0.04, ≤0.035, ≤0.03, ≤0.025, ≤0.02, ≤0.015, ≤0.01% by weight.

[0071] Ti in the core layer enhances its strength and corrosion resistance through solid solution strengthening. However, excessive Ti content can lead to the formation of large intermetallic compounds, reducing the alloy's workability. Therefore, the Ti content in the core layer must be controlled within a suitable range.

[0072] In one embodiment, the Ti content in the core layer is ≤0.05% by weight, preferably ≤0.025%, for example ≤0.05, ≤0.045, ≤0.04, ≤0.035, ≤0.03, ≤0.025, ≤0.02, ≤0.015, ≤0.01% by weight, based on the total weight of the core layer.

[0073] Adding Zr to the core layer can further improve the strength of the alloy after brazing and control the size of recrystallized grains. However, when the Zr content is too high, it can easily form large intermetallic compounds, reducing the alloy's workability. Therefore, the Zr content in the core layer needs to be controlled within a suitable range.

[0074] In one embodiment, based on the total weight of the core layer, the Zr content in the core layer is ≤0.05% by weight, preferably ≤0.025%, for example ≤0.05, ≤0.045, ≤0.04, ≤0.035, ≤0.03, ≤0.025, ≤0.02, ≤0.015, ≤0.01% by weight.

[0075] In one embodiment, based on the total weight of the core layer, the total amount of Cr, Ti, and Zr in the core layer is less than 0.1% by weight.

[0076] In one embodiment, the core layer of the present invention comprises one, two, or three of the following: Si, Fe, Cu, Mg, Mn, Ni, Zn, Al, and Cr, Ti, and Zr. Among them, based on the total weight of the core material layer, the core material layer contains: The Si content is 0.1 to 0.6% by weight. The Fe content is 0.2% to 0.7% by weight. The total amount of Cu and Mg is 1.2 to 3.3% by weight, and the weight ratio of Cu to Mg is 0.6 to 5. The total amount of Cu and Mn is 1.2 to 3.3% by weight, and the weight ratio of Cu to Mn is 1 to 3. The Ni content is 0.03 to 0.5% by weight. The Zn content is 0.05 to 0.5% by weight; and The content of each of Cr, Ti and Zr is less than 0.05% by weight, and the total content is less than 0.1% by weight.

[0077] electrical conductivity

[0078] Brazing alloys involves a high-temperature treatment process. This high-temperature treatment may cause the precipitation of strengthening phases in the alloy, thus affecting its electrical conductivity.

[0079] Conductivity can be measured using conventional equipment in the art, such as the Fischer Sigmascope handheld conductivity meter. To reduce the impact of measurement errors, multiple measurements can be taken at different points on the same sample, and then the average value can be calculated. An exemplary procedure is described in the Examples section below.

[0080] In one embodiment, prior to brazing, the conductivity of the core layer of the present invention is 43 to 55% IACS, preferably 44 to 54% IACS, for example 43, 43.5, 44, 44.5, 45, 45.3, 45.4, 45.5, 45.7, 46, 46.5, 46.9, 47, 47.5, 47.8, 48, 48.5, 49, 49.5, 50, 50.1, 50.5, 51, 51.5, 52, 52.5, 52.9, 53, 53.4, 53.5, 54, 54.5, 55% IACS, and a range consisting of any two of these values.

[0081] In one embodiment, after brazing, the conductivity of the core layer of the present invention is 32 to 42% IACS, preferably 33 to 41% IACS, for example 32, 32.5, 33, 33.5, 34, 34.2, 34.4, 34.5, 34.6, 35, 35.3, 35.5, 36, 36.3, 36.5, 37, 37.2, 37.5, 37.6, 38, 38.4, 38.5, 39, 39.2, 39.5, 40, 40.5, 41, 41.5, 42% IACS, and a range consisting of any two of these values.

[0082] In one embodiment, the difference in conductivity of the core layer of the present invention before and after brazing is 8 to 16% IACS, preferably 9 to 15% IACS, for example 8, 8.5, 9, 9.5, 10, 10.5, 10.8, 11, 11.1, 11.3, 11.5, 11.6, 11.9, 12, 12.5, 12.9, 13, 13.5, 14, 14.2, 14.5, 15, 15.5, 16% IACS, and a range consisting of any two of these values.

[0083] In one embodiment, the change rate of electrical conductivity of the core layer of the present invention before and after brazing is 18% to 30%, preferably 19% to 29%, for example 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.16%, 23.5%, 23.79%, 24%, 24.04%, 24.06%, 24.5%, 24.73%, 25%, 25.5%, 25.75%, 26%, 26.5%, 26.59%, 27%, 27.41%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, and a range consisting of any two of these values.

[0084] Diffuse phase

[0085] Dispersed phases refer to fine, stable, and typically insoluble second-phase particles that are uniformly distributed within an alloy matrix. The size of dispersed phase particles is generally in the nanometer to submicron range.

[0086] Dispersed phases in alloys can affect their physical strength through various mechanisms. First, dispersed phase particles act as physical barriers, hindering dislocation slip within the crystal. When a dislocation encounters an indeformable, hard particle, it must bypass or cut through the particle, requiring additional energy. Therefore, the presence of dispersed phase particles can increase the yield strength of the material. Second, dispersed phases typically possess high melting points, high thermal stability, and are not easily coarsened or dissolved at high temperatures. Thus, dispersed phases help alloys maintain high strength and creep resistance at high temperatures. Furthermore, dispersed phase particles can pin grain boundaries, inhibiting grain growth and thus refining the grain size, further enhancing the alloy's strength.

[0087] However, excessive or overly large dispersed phases can become crack initiators, reducing the alloy's plasticity and toughness. Therefore, it is necessary to control the size, volume fraction, and distribution uniformity of the dispersed phases to balance the alloy's strength and ductility.

[0088] The size and number density of the dispersed phase can be measured using electron microscopy, and the composition of the dispersed phase can be determined using energy dispersive spectroscopy (EDS). Exemplary operating methods are described in the Examples section below.

[0089] In one embodiment, the size of the dispersed phase in the core layer of the present invention is 0.05 to 0.3 μm.

[0090] In one embodiment, the number density of the dispersed phase in the core layer of the present invention is: 1×10 4 Up to 5×10 4 pcs / mm 2 Preferred 1.2×10 4Up to 4.5×10 4 pcs / mm 2 For example, 1×10 4 1.05×10 4 1.1×10 4 1.15×10 4 1.2×10 4 1.25×10 4 1.3×10 4 1.35×10 4 1.37×10 4 1.4×10 4 1.44×10 4 1.45×10 4 1.5×10 4 1.55×10 4 1.6×10 4 1.65×10 4 1.7×10 4 1.75×10 4 1.8×10 4 1.85×10 4 1.9×10 4 1.95×10 4 2×10 4 2.05×10 4 2.1×10 4 2.15×10 4 2.2×10 4 2.25×10 4 2.3×10 4 2.35×10 4 2.4×10 4 2.45×10 4 2.48×10 4 2.5×10 4 2.53×10 4 2.55×10 4 2.6×10 4 2.65×10 4 2.7×10 4 2.75×10 4 2.8×10 4 2.85×10 4 2.9×10 4 2.95×10 4 3×10 4 3.05×10 4 3.07×10 43.1×10 4 3.14×10 4 3.15×10 4 3.2×10 4 3.22×10 4 3.25×10 4 3.3×10 4 3.35×10 4 3.4×10 4 3.45×10 4 3.5×10 4 3.55×10 4 3.6×10 4 3.65×10 4 3.7×10 4 3.75×10 4 3.8×10 4 3.85×10 4 3.9×10 4 3.95×10 4 4×10 4 4.05×10 4 4.1×10 4 4.11×10 4 4.15×10 4 4.2×10 4 4.21×10 4 4.25×10 4 4.3×10 4 4.35×10 4 4.4×10 4 4.45×10 4 4.5×10 4 4.55×10 4 4.6×10 4 4.65×10 4 4.7×10 4 4.75×10 4 4.8×10 4 4.85×10 4 4.9×10 4 4.95×10 4 5×10 4 pcs / mm 2 , and the range consisting of any two of these values.

[0091] Furthermore, different types of dispersed phases differ in their structure, hardness, interfacial properties with the matrix, thermal stability, and chemical properties. Therefore, based on the mechanism described above, the influence of the type of dispersed phase on material strength also varies.

[0092] In one embodiment, the dispersed phase in the core layer of the present invention comprises AlMnFeSi and / or AlMnCu dispersed phases.

[0093] In one embodiment, the dispersed phase in the core layer of the present invention is an AlMnFeSi and / or an AlMnCu dispersed phase.

[0094] Enhanced precipitation phase

[0095] Strengthening precipitates refer to fine, dispersed second-phase particles that precipitate from the supersaturated solid solution after the alloy has undergone solution treatment and aging (natural aging / artificial aging).

[0096] Strengthening precipitates in alloys can affect the physical strength of the alloy through various mechanisms. For fine, coherent, or semi-coherent, shearable precipitates, dislocations can directly pass through the precipitate particles. However, this process requires overcoming several obstacles. For example, due to the slight difference in lattice constant between the coherent precipitate and the matrix, the surrounding matrix generates an elastic distortion field, requiring additional work for dislocations to enter this strain field; the shear modulus of the precipitate differs from that of the matrix, causing energy changes when dislocations pass through. If the precipitate is harder, dislocations tend to bypass it; if they can cut through, additional stress is required; when a dislocation cuts through the precipitate, it breaks the chemical bonds at the precipitate-matrix interface, increasing the interface area. In this case, additional energy is needed to create a new interface. For coarse, incoherent, and non-deformable precipitates, dislocations cannot cut through them and can only bypass the particles. In this process, the dislocations must bend into an arc shape to bypass the obstacle, thus increasing the elastic strain energy.

[0097] The size and number density of the enhanced precipitate can be measured using transmission electron microscopy, and the composition of the enhanced precipitate can be determined using energy dispersive spectroscopy (EDS). Exemplary operating methods are described in the Examples section below.

[0098] Since the aluminum alloy composite material of the present invention does not require artificial aging after brazing, the reinforcing precipitates in the core layer can precipitate smoothly under natural aging conditions. Based on the mechanism described above, the type of reinforcing precipitate has a different effect on the material strength.

[0099] In one embodiment, the reinforcing precipitate in the core layer of the present invention comprises AlCuMg and / or AlCu reinforcing precipitates.

[0100] In one embodiment, the reinforcing precipitate in the core layer of the present invention is an AlCuMg and / or an AlCu reinforcing precipitate.

[0101] In one embodiment, the strengthening precipitate of the present invention is the strengthening precipitate after brazing and natural aging. The natural aging time after brazing depends on factors such as the material composition, the microstructure of the material, the brazing temperature and time, the brazing cooling rate, and the ambient temperature. The natural aging time of the aluminum alloy composite material of the present invention after brazing can be 4 to 14 days, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 days, and a range consisting of any two of these values.

[0102] Texture

[0103] Texture refers to the phenomenon where randomly oriented grains within a polycrystalline material align in a regular pattern along a specific direction. The distribution of texture can influence the mechanical properties of an alloy, such as strength, plasticity, and toughness, as well as its physical properties, such as electrical conductivity and magnetism. Therefore, texture distribution is a crucial microscopic parameter determining the properties of alloy materials.

[0104] The distribution of texture can be measured using field emission electron microscopy, and exemplary operating methods are described in the Examples section below.

[0105] In one embodiment, the core layer of the present invention comprises a cube texture.

[0106] In one embodiment, the area of ​​the cube texture of the core layer of the present invention accounts for 5% to 12% of the total area of ​​the material, preferably 6% to 11%, for example 6%, 6.32%, 6.47%, 6.5%, 7%, 7.23%, 7.42%, 7.5%, 8%, 8.5%, 8.54%, 8.81%, 8.97%, 9%, 9.5%, 10%, 10.15%, 10.37%, 10.67%, 10.5%, 11%, and a range consisting of any two of these values.

[0107] In one embodiment, the core layer of the present invention comprises a cube. ND Texture.

[0108] In one embodiment, the cube of the core material layer of the present invention NDThe area of ​​the texture accounts for 6% to 12% of the total area of ​​the material, preferably 7% to 11%, for example 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.02%, 9.05%, 9.11%, 9.14%, 9.20%, 9.21%, 9.26%, 9.37%, 9.5%, 9.55%, 9.68%, 10%, 10.5%, 11%, 11.5%, 12%, and a range consisting of any two of these values.

[0109] In one embodiment, the cube texture and cube in the core layer of the present invention ND The total area of ​​the texture accounts for 14% to 22% of the total area of ​​the material, preferably 15% to 21%, for example 15%, 15.5%, 15.68%, 15.69%, 16%, 16.5%, 16.91%, 16.97%, 17%, 17.5%, 17.65%, 17.83%, 18%, 18.17%, 18.5%, 19%, 19.29%, 19.42%, 19.5%, 19.93%, 20%, 20.5%, 21%, and a range consisting of any two of these values.

[0110] Intermediate layer

[0111] In this invention, the intermediate layer is in direct contact with the core layer. In the case of a brazing layer, the intermediate layer is located between the core layer and the brazing layer. An intermediate layer with a suitable composition and thickness can achieve the effects of corrosion prevention, erosion prevention, and prevention of element diffusion from the core layer and the brazing layer (e.g., Mg from the core layer diffuses into the brazing layer, Si from the brazing layer diffuses into the core layer, etc.).

[0112] In one embodiment, the aluminum alloy composite material of the present invention may include one or two intermediate layers. When one intermediate layer is included, it is located on one side of the core layer. When two intermediate layers are included, they are located on both sides of the core layer, respectively.

[0113] An appropriate composite ratio for the intermediate layer helps it function effectively. If the composite ratio is too high, the strength of the composite material decreases; if the composite ratio is too low, it cannot function effectively.

[0114] In one embodiment, the composite ratio of the intermediate layer is 3% to 28%, preferably 4% to 26%, for example 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, and a range consisting of any two of these values.

[0115] Si can form AlMnSi dispersed phase particles with Mn, playing a role in dispersion strengthening. The fine dispersed particles can control the recrystallization process and affect the size and orientation of the recrystallized grains. In addition, the Si in the intermediate layer also has a pinning effect on the diffusion of Mg.

[0116] In one embodiment, the Si content in the intermediate layer can be 0.3 to 1.0 wt%, preferably 0.5 to 0.9 wt%, for example 0.3, 0.4, 0.5, 0.55, 0.6, 0.67, 0.7, 0.8, 0.84, 0.9, 1 wt%, and a range consisting of any two of these values, based on the total weight of the intermediate layer.

[0117] Fe in the intermetallic layer forms intermetallic compounds in the aluminum, reducing the alloy's corrosion resistance. Therefore, the Fe content in the intermetallic layer needs to be controlled.

[0118] In one embodiment, the Fe content in the intermediate layer can be 0.05 to 0.4% by weight, preferably 0.1 to 0.3% by weight, based on the total weight of the intermediate layer, for example, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4% by weight, and a range consisting of any two of these values.

[0119] The intermediate layer contains a low amount of Mg, which helps prevent Mg from diffusing from the core layer into the solder layer, thus avoiding the poisoning effect of Mg on the F-Al-K flux.

[0120] In one embodiment, based on the total weight of the intermediate layer, the Mg content in the intermediate layer can be from 0.005 to 0.05% by weight, preferably from 0.008 to 0.03% by weight, for example, 0.005, 0.008, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05% by weight, and a range consisting of any two of these values.

[0121] Mn is the basis for the formation of various particles, and Mn-containing dispersed particles can affect the recrystallization process of grains during brazing. Appropriate Mn content can improve the strength and corrosion resistance of materials.

[0122] In one embodiment, based on the total weight of the intermediate layer, the Mn content in the intermediate layer can be from 0.04 to 1.2% by weight, preferably from 0.05 to 1% by weight, for example, 0.04, 0.06, 0.1, 0.2, 0.3, 0.32, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99, 1.0, 1.1, 1.2% by weight, and a range consisting of any two of these values.

[0123] The intermediate layer also contains Zn. On one hand, during brazing, Zn diffuses from the intermediate layer to the core layer, creating a gradient distribution of Zn from the intermediate layer to the core layer, thus improving the overall corrosion resistance. On the other hand, Mg in the core material diffuses into the intermediate layer, and Zn pins the diffusion of Mg and forms MgZn2 nanoscale reinforcing phase particles with Mg, increasing the strength of the intermediate layer alloy and further improving the overall strength of the material.

[0124] In one embodiment, the Zn content in the intermediate layer is 0.05 to 5% by weight, preferably 0.06 to 4.5% by weight, for example, 0.05, 0.08, 1, 1.5, 1.85, 2, 2.5, 3, 3.5, 4, 4.23, 4.5, 5% by weight, and a range consisting of any two of these values, based on the total weight of the intermediate layer.

[0125] The effects of the other elements in the intermediate layer alloy are as described above.

[0126] In one embodiment, the intermediate layer of the aluminum alloy material of the present invention comprises Si, Mg, Zn, Al, and optionally one, two, or three of Mn, Ti, and Zr; Among them, based on the total weight of the intermediate layer, The Si content is 0.3 to 1.0% by weight, preferably 0.5 to 0.9% by weight; The Mg content is 0.005 to 0.05% by weight, preferably 0.008 to 0.03% by weight; The Zn content is 0.05 to 5.0%, preferably 0.06 to 4.5% by weight.

[0127] Controlling the initial melting temperatures of the core layer and the intermediate layer can effectively prevent core material erosion during brazing. The initial melting temperature of the intermediate layer is at least 10 °C higher than that of the core layer, thus preventing core material erosion during conventional brazing. In this article, brazing refers to the brazing process commonly used in this field. For example, the target temperature during brazing can be 600 °C, and the specific parameters can be appropriately adjusted according to the brazing environment, the parts to be brazed, and the brazing area to form a high-quality brazed joint. The heating rate from room temperature to 550 °C is generally 30 °C / min, and the heating rate from 550 °C to the target temperature of 600 °C is generally 10 °C / min, with a holding time of generally 3 minutes. These adjustments can be made depending on the size of the heat exchanger and the brazing furnace.

[0128] The composition of the core layer and the intermediate layer affects their respective melting point. The core layer and the intermediate layer of this application have suitable compositions such that the melting point of the intermediate layer is at least 10 °C higher than that of the core layer.

[0129] The formation of grains of a certain size in the interlayer after brazing helps improve erosion resistance, thereby enhancing corrosion resistance. The average grain size of the interlayer after brazing can be above 80 μm, preferably above 100 μm. If the average grain size is too small, the interlayer cannot effectively prevent element diffusion and block the erosion of the molten solder, which may lead to core erosion, reducing the potential difference between the core material and the interlayer, and potentially decreasing corrosion resistance. The average grain size of the interlayer after brazing can be controlled by adjusting its chemical composition and by controlling its manufacturing process (e.g., heat treatment).

[0130] brazing layer

[0131] The multilayer aluminum alloy composite material of the present invention may optionally include a brazing layer. The brazing layer may cover the outer surface of the intermediate layer to impart brazing properties to the composite material.

[0132] In one embodiment, the brazing layer is located on one or both sides of the intermediate layer away from the core layer.

[0133] In one embodiment, the aluminum alloy composite material of the present invention comprises a core layer, two intermediate layers, and two brazing layers, wherein: The two intermediate layers are located on either side of the core layer; and One of the brazing layers is located on one side of the intermediate layer away from the core layer, and the other brazing layer is located on another side of the intermediate layer away from the core layer.

[0134] In one embodiment, the brazing layer of the present invention can be an aluminum-silicon alloy, and in particular, the brazing layer can be an AA4XXX series alloy, such as AA4343, AA4045, etc.

[0135] In one embodiment, the brazing layer comprises Si, Fe, Cu, Mn, Zn, and Al, wherein, based on the total weight of the brazing layer, the brazing layer contains: The Si content is 8 to 12% by weight. The Fe content is 0.05 to 0.3% by weight. The Cu content is 0.01 to 0.3% by weight. The Mn content is 0.005 to 0.03% by weight. The Zn content is 0.005 to 0.03 by weight.

[0136] The thickness of the brazing layer affects the brazing performance of composite materials. Too thin or too thick a layer is detrimental to imparting good brazing results to the composite material.

[0137] In one embodiment, the composite ratio of the brazing layer of the present invention can be 5% to 25%, preferably 6% to 21%, for example 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, and a range consisting of any two of these values.

[0138] Preparation of aluminum alloy composite materials

[0139] This invention relates to a method for preparing the aluminum alloy composite material of this invention, comprising the following steps: Prepare the alloy of the core layer, intermediate layer, and optional brazing layer; The core layer alloy and the intermediate layer alloy were heat-treated separately. A composite is obtained by alloying a core layer, an intermediate layer, and an optional brazing layer; The composite is heat-treated and then rolled to the target thickness; annealing.

[0140] Select appropriate raw materials to prepare a core layer, an intermediate layer, and an optional brazing layer having the composition described above.

[0141] Heat treatment helps to form the desired microstructure within the layer. After heat treatment, the interlayer alloy is rolled into a plate shape to obtain a plate-shaped interlayer alloy. Appropriate heat treatment can control the average grain size and elemental segregation in the interlayer alloy, thus affecting its average grain size after brazing.

[0142] The heat treatment temperature for the core layer alloy can be between 490 and 570°C. The heat treatment temperature for the intermediate layer alloy can be between 500 and 580°C.

[0143] The alloy layers can be processed using relevant techniques (such as sawing and milling).

[0144] A composite is obtained by sequentially stacking a core layer alloy, a plate-shaped intermediate layer alloy, and an optional plate-shaped brazing layer alloy. Those skilled in the art will understand that the stacking order can be designed according to the desired composite material. The relative positional relationships of the plate-shaped alloys in the composite are the same as those in the final composite material.

[0145] The composite is rolled to the target thickness. Rolling methods may include hot rolling, cold rolling, and combinations thereof.

[0146] The resulting composite material of the final thickness is then annealed. Annealing reduces rolling oil residue, eliminates internal stress, and lowers strength, preventing cracking during subsequent processing. The annealing temperature can be appropriately selected based on the specific composition of the brazing aluminum alloy composite material. However, it should be lower than the melting temperature of the brazing filler metal contained in the brazing aluminum alloy composite material to avoid melting of the filler metal during annealing.

[0147] In one embodiment, the annealing temperature is 300 to 400°C, preferably 320 to 380°C.

[0148] The preparation method of this invention can endow composite materials with desired structures (multilayer structures, microparticle state) and material properties. The obtained composite materials have high strength and excellent corrosion resistance.

[0149] Accordingly, the present invention also relates to an aluminum alloy composite material prepared by the method of the present invention.

[0150] Aluminum alloy brazed parts and their preparation

[0151] Brazing is a joining technique that uses heat to melt a filler metal with a melting point lower than that of the base metal. Without melting the base metal, the liquid filler metal flows into and wets the joint gap through capillary action, and after cooling, a strong metallurgically bonded joint is formed.

[0152] The aluminum alloy composite material of the present invention is particularly suitable for brazing; therefore, the present invention also relates to an aluminum alloy brazing component made of the aluminum alloy composite material of the present invention.

[0153] The method for preparing the aluminum alloy brazed part includes: providing the aluminum alloy composite material of the present invention and brazing.

[0154] During brazing, the filler metal needs to be melted at high temperatures. However, an oxide film easily forms on the metal surface during heating. This oxide film covers the filler metal surface, increasing the contact angle between the filler metal and the base metal, thus preventing the filler metal from flowing smoothly into the joint gap and significantly reducing the brazing effect. Furthermore, the strength of a brazed joint mainly depends on atomic diffusion and possible interfacial reactions between the filler metal and the base metal, such as the formation of solid solutions or intermetallic compounds. However, the oxide film acts as a physical barrier, isolating the filler metal from direct contact with the base metal and inhibiting the diffusion process, thereby reducing the joint strength.

[0155] To address the issue of oxide formation during brazing, flux can be added during the process. On one hand, flux can remove metal oxide films through chemical dissolution or reaction. On the other hand, the flux coating on the metal surface forms a protective film, isolating the solder from oxygen and preventing oxide film formation.

[0156] In addition, brazing can also be performed in a vacuum or protective atmosphere, such as nitrogen (N2), argon (Ar), or hydrogen (H2), to isolate the brazing filler metal from oxygen and thus prevent the formation of an oxide film during the brazing process.

[0157] After brazing, artificial aging treatment is usually required to increase the strength of the material. However, artificial aging requires a dedicated heat treatment furnace and a certain holding time, which increases production costs. The aluminum alloy material of this invention, through the adjustment of the element content of each layer and the scientific ratio of the composite structure, enables brazed parts made from the aluminum alloy material of this invention to achieve ideal strength through natural aging treatment without artificial aging treatment.

[0158] Therefore, in one embodiment, the method for preparing the aluminum alloy brazed part of the present invention further includes placing the brazed material at room temperature for natural aging treatment.

[0159] In one embodiment, the aluminum alloy brazed part of the present invention is not artificially aged.

[0160] In one embodiment, the method for preparing the aluminum alloy brazed part of the present invention does not include the step of artificial aging treatment.

[0161] Accordingly, the present invention also relates to an aluminum alloy brazing component, which is prepared by the method of the present invention.

[0162] heat exchanger

[0163] A heat exchanger is a device used to transfer heat between two or more fluids, such as liquids or gases. Its main purpose is to achieve efficient heat exchange without directly mixing the fluids. Heat exchangers are widely used in many industrial fields, including chemical, petroleum, power, refrigeration, heating, ventilation and air conditioning (HVAC), food processing, shipbuilding, and aerospace.

[0164] The brazable aluminum alloy composite material of the present invention has the advantages of easy processing, high strength and good corrosion resistance, and is particularly suitable for the manufacture and processing of heat exchangers.

[0165] Therefore, the present invention also relates to a heat exchanger comprising the aluminum alloy composite material of the present invention and / or the aluminum alloy brazed component of the present invention.

[0166] Because the aluminum alloy composite material of the present invention has both high physical strength and good corrosion resistance, it is particularly suitable for use in conditions where structural support is required and ion concentration is high, such as in batteries.

[0167] Therefore, in one embodiment, the heat exchanger of the present invention is a battery heat exchanger.

[0168] In a further implementation plan, the battery is a battery for a new energy vehicle or an energy storage power station.

[0169] Beneficial effects

[0170] Currently, aluminum alloy composite materials for brazing typically use AA3003 or AA3003mod aluminum alloy as the core material. However, AA3003 or AA3003mod aluminum alloy is a non-heat-treatable strengthening alloy. Even after modification, it is impossible to achieve ideal yield strength and tensile strength after high-temperature brazing.

[0171] To improve material strength, Al-Mg-Si aluminum alloys can be used as brazing materials. However, currently used brazable Al-Mg-Si aluminum alloys require artificial aging after brazing to achieve high strength. Artificial aging requires a dedicated heat treatment furnace and a certain holding time. Moreover, when heat treating large-sized battery water-cooling plates, there are high requirements for temperature uniformity across different locations. Artificial aging after brazing increases production costs and affects production efficiency. Furthermore, artificial aging only improves the material's strength and does not positively affect its corrosion resistance. However, with the increasing safety requirements for new energy vehicle power batteries and the release of new national standards for coolants used in battery water-cooling plates, the corrosion resistance of materials used in battery water-cooling plates is receiving increasing attention. There is a need to develop a new type of high-strength aluminum alloy composite material for battery cooling plates that can be brazed, possesses formability, high strength, and corrosion resistance. This aluminum alloy should still have good natural aging strengthening ability under low cooling rate conditions and should not require additional artificial aging treatment, thereby improving production efficiency and reducing production costs.

[0172] To address the aforementioned issues, this application achieves high strength through a well-designed core layer and excellent brazing and corrosion resistance by introducing a rationally designed intermediate layer. The composite material of this application, through the rational combination of its layers, particularly the core layer and the intermediate layer, achieves outstanding mechanical properties and high corrosion resistance without the need for additional artificial aging, thus saving production costs and improving production efficiency.

[0173] The aluminum alloy composite material of this application has excellent mechanical properties and corrosion resistance, and does not require additional artificial aging treatment, making it particularly suitable for the manufacture of heat exchangers, especially battery heat exchangers.

[0174] Example

[0175] The present invention will now be described in further detail with reference to specific embodiments.

[0176] It should be noted that the following embodiments are merely examples to clearly illustrate the technical solutions of the present invention, and are not intended to limit the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here, and obvious variations or modifications derived therefrom are still within the protection scope of this invention. Unless otherwise specified, the instruments, equipment, and reagents used herein are commercially available.

[0177] The composition of the aluminum alloy composite material of the present invention is shown in Table 1.

[0178] Samples of the embodiments and comparative examples of the present invention were prepared according to the following method: The core layer alloy, intermediate layer alloy, and optional brazing layer alloy with specific compositions are melted and cast separately to obtain ingots. The core alloy ingot is heated to 490 to 570 °C at a heating rate of 50 to 100 °C / h and held at that temperature for 5 to 10 hours. Then, it is cooled to 400 to 450 °C at a heating rate of 50 to 100 °C / h and held at that temperature for 3 to 6 hours. Afterward, it is removed from the furnace and cooled to below 120 °C at a cooling rate of 100 to 200 °C / h. The intermediate layer alloy ingot is heated to 500 to 580 ℃ at a heating rate of 50 to 100 ℃ / h and held at that temperature for 5 to 10 hours, and then cooled to below 200 ℃ at a rate of 40 to 80 ℃ / h. The intermediate layer alloy ingot is sawn, milled, and then hot-rolled into a thick plate of the corresponding thickness. After sawing and milling the core alloy ingot, it is combined with thick plates of intermediate layer alloy and optional brazing layer alloy in the corresponding order to obtain the composite body. After the composite is heated in a furnace, it is compounded by hot rolling to produce a composite material with a thickness of 3 to 8 mm. The initial rolling temperature is 450 to 520 ℃ and the final rolling temperature is 280 to 320 ℃. The composite material is cold-rolled into sheets with diameters of 0.8, 1.0, 1.2, or 1.5 mm. After annealing at 320 to 380 °C for 2 h, the composite materials were removed from the furnace and air-cooled to obtain the composite materials of each embodiment and comparative example.

[0179] The structures and components of each layer in the embodiments and comparative examples are shown in Tables 1 and 2 below.

[0180] Table 1

[0181] Table 2

[0182] Brazing simulation and natural aging

[0183] Brazing simulations were performed on the composite materials of the examples and comparative examples: Under nitrogen (N2) protection, the temperature was increased from room temperature to 600 °C over 40 minutes and held for 3 minutes. Afterward, the materials were slowly cooled in a furnace at a rate of 0.2 to 0.5 °C / s. The brazed samples were then allowed to age naturally at room temperature for 7 days to obtain the brazed simulation test materials of the examples and comparative examples. The test materials were then evaluated according to the following methods.

[0184] Mechanical property testing

[0185] Tensile test specimens were prepared from the brazed simulated test material according to EN10002-1 standard, with a gauge length of 50 mm. Tensile tests were conducted at room temperature at a tensile speed of 20 mm / min.

[0186] The test materials simulated by brazing in the embodiments of this application all exhibit high yield strength and tensile strength, demonstrating excellent mechanical properties. Table 3 below shows the specific mechanical property test results of Comparative Examples 11-13 and Examples 1-10. As can be seen from Table 3, the mechanical properties of the samples in Examples 1-10 are superior to those in Comparative Examples 11-13.

[0187] External corrosion test (SWAAT test)

[0188] The brazed simulated test material was tested according to ASTM G85(A3), with a corrosion test period of 40 days. After the experiment, the depth of the 20 deepest corrosion pits was measured, and the average value was taken.

[0189] Table 3 below shows the average depth test results of 20 maximum depth corrosion pits after 40 days of SWAAT testing for Comparative Examples 11-13 and Examples 1-10. As can be seen from Table 3, the corrosion resistance performance of the samples of Examples 1-10 in the SWAAT test is better than that of Comparative Examples 11-13.

[0190] Internal corrosion (OY test)

[0191] The brazed layer side of the simulated brazing test material was sealed and placed in an environment containing 195 ppm Cl. - 60 ppm SO4 2- 1ppm Cu 2+ and 30 ppm Fe 3+ The samples were placed in 88°C high-temperature water for 8 hours, then placed at room temperature for 16 hours for an internal corrosion cycle test, which lasted for 14 days. After the experiment, the depth of the 20 deepest corrosion pits was measured, and the average value was taken.

[0192] Table 3 below shows the average depth test results of 20 maximum depth corrosion holes after 14 days of OY experiments for Comparative Examples 11-13 and Examples 1-10.

[0193] Table 3

[0194] Measurement of conductivity

[0195] The conductivity of the samples was measured before and after the brazing simulation using a handheld conductivity meter (Fischer Sigmascope). The test probe was placed on the sample surface and the temperature of the probe was adjusted to ensure that it was consistent with the sample surface. Then the measurement was started. Three points were tested for each sample and the average value was taken.

[0196] Table 4 below shows the conductivity test results of Comparative Examples 11-13 and Examples 1-10 before and after brazing simulation.

[0197] Table 4

[0198] (Difference before and after brazing simulation / before brazing simulation) × 100%

[0199] Characterization of diffuse phase

[0200] After the brazing simulation test material was cut into 20 mm × 20 mm samples, it was ground and polished. The distribution of the dispersed phase was observed using a FEI NOVA NANO SEM200 electron microscope at a magnification of 10,000 to 30,000 times, and the composition of the dispersed phase was determined by energy dispersive spectroscopy (EDS).

[0201] Characterization of enhanced precipitates

[0202] The brazing-simulated test material was cut into 15 mm × 15 mm samples, and then thinned by sanding with 200 grit, 500 grit, and 1200 grit sandpaper in sequence. When the final sample thickness was less than 0.1 mm, a disc punch was used to punch the sample into a pre-sample with a diameter of 3 mm. Subsequently, the pre-sample was thinned by electrolytic double-spraying in a solution of 30 vol% nitric acid + 70 vol% methanol (the temperature was controlled by dry ice during the process) to complete the preparation of the final transmission electron sample. The distribution of the strengthening precipitates in the sample was observed using a JEOL JEM-F200 transmission electron microscope at a voltage of 200 kV and a magnification of 30,000 to 60,000, and the composition of the strengthening precipitates was determined by energy dispersive spectroscopy (EDS).

[0203] Representation of texture

[0204] The brazed simulated test material was cut into 20 mm × 20 mm samples and mounted. During mounting, the rolling direction of the sample was used as the observation surface, and a thick plate was used as a protective plate and as a conductive contact surface. Then, rough grinding, fine grinding, polishing, and final polishing were performed sequentially to obtain the required metallographic specimens. EBSD testing was then performed using a FEI NOVA NANOSEM200 field emission electron microscope equipped with an EBSD probe. After the testing, Aztec Crystal software was used for data processing to obtain texture percentage data.

[0205] Table 5 below shows the dispersed phase distribution density and texture ratio results of Comparative Examples 11-13 and Examples 1-10 after brazing simulation.

[0206] Table 5

[0207] As shown in Table 3, the aluminum alloy composite materials of Examples 1-10 of this invention have high strength. After 7 days of natural aging, their yield strength exceeds 95 MPa and their tensile strength exceeds 200 MPa. Furthermore, they exhibit good corrosion resistance. After 40 days of SWAAT accelerated corrosion testing, the average corrosion depth is less than 30% of the original material thickness, and after 14 days of OY accelerated corrosion testing, the average corrosion depth is less than 25% of the original material thickness. In contrast, the materials in the comparative examples are significantly weaker than those in the examples in terms of both strength and corrosion resistance.

[0208] In summary, the aluminum alloy composite material of the present invention can achieve high strength without additional artificial aging heat treatment and has good corrosion resistance. It is suitable for sheet metal applications that require high strength after brazing and higher corrosion resistance, and has broad market prospects.

[0209] The technical content and features of this disclosure have been disclosed above. However, it is understood that those skilled in the art can make various changes and improvements to the above-disclosed concept under the inventive concept of this disclosure, but these changes and improvements fall within the protection scope of this disclosure. The description of the above embodiments is exemplary and not restrictive, and the protection scope of this disclosure is determined by the claims.

Claims

1. An aluminum alloy composite material, comprising: Core layer and at least one intermediate layer, The core material layer comprises one, two, or three of the following: Si, Fe, Cu, Mg, Mn, Ni, Zn, Al, Cr, Ti, and Zr. in, Based on the total weight of the core layer, the core layer contains: The Si content is 0.1 to 0.6% by weight. The Fe content is 0.2% to 0.7% by weight. The total amount of Cu and Mg is 1.8 to 3% by weight, and the weight ratio of Cu to Mg is 0.8 to 3.

5. The total amount of Cu and Mn is 1.6 to 3% by weight, and the weight ratio of Cu to Mn is 1 to 2.

2. The Ni content is 0.03 to 0.5% by weight. The Zn content is 0.05 to 0.5% by weight; and The content of each of Cr, Ti, and Zr is less than 0.05% by weight, and the total content is less than 0.1% by weight. After brazing, the number density of the dispersed phase in the core layer is 1×10⁻⁶. 4 Up to 5×10 4 pcs / mm 2 , The intermediate layer comprises Si, Mg, Zn, Al, and optionally one, two, or three of Mn, Ti, and Zr, wherein, based on the total weight of the intermediate layer: The Si content is 0.3 to 1.0% by weight. The Mg content is 0.005 to 0.05% by weight. The Zn content ranges from 0.05% to 5.0%. The aluminum alloy composite material has the following properties: (a) The difference in electrical conductivity before and after brazing of the core layer is 8 to 16% IACS; (b) The change in conductivity of the core layer before and after brazing is 18% to 30%; (c) After brazing, the size of the dispersed phase in the core layer is 0.05 to 0.3 μm; (d) After brazing, the core layer contains AlMnFeSi and / or AlMnCu dispersed phases; (e) After brazing, the core layer contains AlCuMg and / or AlCu reinforced precipitates; (f) After brazing, the Cube in the core layer ND The area of ​​the texture accounts for 6% to 12% of the total material area; (g) After brazing, the cube texture and cube in the core layer ND The total area of ​​the texture accounts for 14% to 22% of the total material area. The preparation method of the aluminum alloy composite material includes: Provide a core layer and an intermediate layer; The core layer and the intermediate layer are heat-treated separately. A composite material is obtained by combining a core layer and an intermediate layer; The composite is heat-treated and then rolled to the target thickness; annealing.

2. The aluminum alloy composite material according to claim 1, wherein, Based on the total weight of the core layer, the core layer contains: The Fe content is 0.3 to 0.6% by weight; and / or The Cu content is 0.8 to 1.8% by weight; and / or The Mg content is 0.4 to 1.5% by weight; and / or The Mn content is 0.4 to 1.5% by weight; and / or The Ni content is 0.05 to 0.3% by weight.

3. The aluminum alloy composite material according to claim 1, wherein, The aluminum alloy composite material comprises two intermediate layers, which are located on both sides of the core layer.

4. The aluminum alloy composite material according to claim 1, wherein, The aluminum alloy composite material also includes a brazing layer, which is located on one or both sides of the intermediate layer away from the core material layer.

5. The aluminum alloy composite material according to claim 4, wherein the preparation method of the aluminum alloy composite material includes: It provides a core layer, an intermediate layer, and a solder layer; The core layer and the intermediate layer are heat-treated separately. A composite material is obtained by alloying the core layer, intermediate layer and brazing layer; The composite is heat-treated and then rolled to the target thickness; annealing.

6. The aluminum alloy composite material according to claim 4, wherein, The brazing layer is an aluminum-silicon alloy.

7. The aluminum alloy composite material according to claim 1, comprising a core layer, two intermediate layers, and two brazing layers, wherein: The two intermediate layers are located on either side of the core layer; and One of the brazing layers is located on one side of the intermediate layer away from the core layer, and the other brazing layer is located on another side of the intermediate layer away from the core layer.

8. The aluminum alloy composite material according to claim 1, wherein it has not undergone artificial aging treatment after brazing.

9. The aluminum alloy composite material according to any one of claims 1-8, wherein it has one or more of the following properties: (a) After 7 days of natural aging, the yield strength is ≥95MPa; (b) After 7 days of natural aging, the tensile strength is ≥200MPa; (c) After 40 days of SWAAT accelerated corrosion testing, the average corrosion depth was less than 30% of the original material thickness; and (d) After 14 days of accelerated corrosion by OY, the average corrosion depth was less than 25% of the original material thickness.

10. An aluminum alloy brazing component made of any one of the aluminum alloy composite materials according to claims 1-9.

11. The aluminum alloy brazed part according to claim 10, wherein, The aluminum alloy brazed parts were not artificially aged.

12. A heat exchanger comprising the aluminum alloy brazed component as described in claim 10 or 11.

13. The heat exchanger according to claim 12, wherein, The heat exchanger is a battery heat exchanger.

14. The heat exchanger according to claim 13, wherein, The battery is used in new energy vehicles or energy storage power stations.

15. A method for preparing the aluminum alloy brazed part according to claim 10 or 11, comprising: Provide an aluminum alloy composite material according to any one of claims 1-9; Brazing; The brazed materials are left to age naturally at room temperature.

16. The method according to claim 15, wherein, The method does not include the step of performing manual aging processing.

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