A magnesium-based composite material and a method for producing the same

Abstract

The application provides a magnesium-based composite material and a preparation method thereof. The magnesium-based composite material comprises at least two layers of magnesium alloy substrates and a reinforcing phase arranged between the two layers of magnesium alloy substrates. The magnesium-based composite material satisfies at least one of the following conditions: (1) the thermal conductivity is greater than or equal to 210 W / (m*K); and (2) the linear thermal expansion coefficient is 18-25 ppm / K. The method of the application does not need to use magnesium powder, but directly uses commercial magnesium alloy sheets, realizes the compounding with plated diamond particles through a laminated rolling process, and is safe, simple and easy to industrialize.

Description

Technical Field

[0001] This application relates to the field of metal matrix composites technology, and in particular to a magnesium matrix composite material and its preparation method. Background Technology

[0002] With the rapid development of electronic devices towards high power and miniaturization, the performance requirements for heat dissipation materials (also known as thermal management materials) are becoming increasingly stringent. An ideal thermal management material must simultaneously possess high thermal conductivity, low density, and an adjustable coefficient of thermal expansion to ensure the stability and reliability of electronic devices during efficient operation and to adapt to thermal stress matching between different components. Magnesium alloys have attracted attention due to their low density, but their thermal conductivity is relatively limited, typically ranging from tens to over one hundred W / (m·K), making it difficult to meet the demands of efficient heat dissipation. Diamond, on the other hand, possesses extremely high thermal conductivity (exceeding 2000 W / (m·K), making it one of the best-performing materials known for its thermal conductivity; however, its high brittleness, processing difficulties, and high cost make it unsuitable for use as a standalone structural material. Therefore, combining magnesium alloys with diamond theoretically integrates the advantages of both, forming a lightweight, high-thermal-conductivity composite material. Through interface design and structural optimization, it is hoped that the coefficient of thermal expansion can be controlled, becoming an effective way to solve the challenges of thermal management.

[0003] In existing technologies, the preparation of magnesium / diamond composites mainly employs powder metallurgy or gas pressure infiltration. Powder metallurgy involves mixing magnesium powder and diamond particles, then pressing and sintering to form the composite material. However, magnesium powder has extremely high chemical reactivity and readily reacts with oxygen during preparation, storage, and transportation, leading to oxidation or even combustion and explosion, posing serious safety hazards and increasing production costs and operational complexity. Furthermore, the oxide layer reduces the interfacial bonding strength and thermal conductivity of the composite material. Gas pressure infiltration involves impregnating molten magnesium alloy into a diamond preform under high pressure. This method requires complex pressurizing equipment and high-precision molds, with demanding process conditions. Moreover, when preparing large-size plates, ensuring uniform impregnation is difficult, easily resulting in defects and low production efficiency, thus limiting its large-scale application. In addition, both methods still face challenges in controlling interfacial reactions and optimizing the material's microstructure, affecting the overall performance of the final composite material. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this application provides a magnesium-based composite material and its preparation method, which does not require the use of magnesium powder, but directly uses commercially available magnesium alloy thin plates, and achieves composite with coated diamond particles through a lamination rolling process. The process is safe, simple and easy to industrialize.

[0005] The first aspect of this application provides a magnesium-based composite material, comprising at least two magnesium alloy matrices and a reinforcing phase disposed between the two magnesium alloy matrices; The magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ≥ 210 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 25 ppm / K.

[0006] In some specific embodiments, the magnesium alloy matrix satisfies at least one of the following conditions: (1) Tensile strength is 200-300 MPa; (2) Yield strength is 150-200 MPa; (3) The elongation rate is 8-12%; (4) The magnesium alloy matrix includes a magnesium alloy sheet; The magnesium alloy sheet is an AZ31B or ZK60 rolled sheet, and the thickness of the magnesium alloy sheet is 0.5 mm to 1.0 mm.

[0007] In some specific embodiments, the volume fraction of the reinforcing phase is 10% to 30% based on the volume of the composite material; Preferably, the reinforcing phase comprises diamond particles with a particle size of 10 μm to 50 μm.

[0008] In some specific embodiments, the surface of the diamond particles is provided with a coating, the thickness of which is 0.5 μm to 1 μm; Preferably, the coating includes any one of a titanium coating, a zirconium coating, or a chromium coating.

[0009] In some specific embodiments, the magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ranges from 210 W / (m·K) to 305 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 22 ppm / K.

[0010] A second aspect of this application provides a method for preparing the magnesium-based composite material, comprising the following steps: S1. Magnesium alloy matrix pretreatment The surfaces of the magnesium alloy substrates to be composited, consisting of at least two layers, are activated to remove the oxide film on the surface of the magnesium alloy substrates, forming an activated surface and thus obtaining an activated magnesium alloy substrate. S2. Stacking Diamond particles with a coating are obtained, and the diamond particles are evenly distributed on the activated surface of the activated magnesium alloy matrix. Then, multiple layers of magnesium alloy matrix are stacked to form a stacked blank with alternating layers of "magnesium alloy matrix-diamond particles-magnesium alloy matrix". S3. Encapsulation The laminated blank is placed in a sleeve, vacuumed, and then sealed. S4. Hot-rolled composite The sealed casing is heated and then rolled to cause plastic deformation of the magnesium alloy matrix, press diamond particles into the magnesium alloy matrix, and connect the multiple layers of magnesium alloy matrix through diamond particles to obtain a rolled composite plate. S5. Heat Treatment The rolled composite plate is heat-treated to promote the diffusion reaction between the metal coating on the surface of the diamond particles and the magnesium alloy matrix, forming a good interfacial metallurgical bond.

[0011] In some specific embodiments, the activation treatment described in step S1 includes mechanical polishing and chemical activation; Preferably, after the activation treatment, a copper interlayer or a nickel interlayer is pre-plated on the surface to be composited.

[0012] In some specific embodiments, the sleeve mentioned in step S3 is a stainless steel sleeve.

[0013] In some specific implementations, step S4 satisfies at least one of the following conditions: (1) The heating temperature is 350°C to 400°C; (2) The rolling process is a multi-pass rolling process; in the first pass of the multi-pass rolling process, the reduction rate is 30% to 50%.

[0014] In some specific embodiments, the heat treatment in step S5 satisfies at least one of the following conditions: (1) The temperature of the heat treatment is 500℃ to 550℃; (2) The heat treatment holding time is 1 to 4 hours; (3) The heat treatment is carried out under vacuum or protective atmosphere.

[0015] Compared with the prior art, this application has the following beneficial effects: The magnesium-based composite material described in this application employs a layered structure with a multi-layered magnesium alloy matrix sandwiched with reinforcing phases, which helps to construct a uniform thermal conductivity pathway while relying on the magnesium alloy matrix to ensure the overall mechanical properties of the material. This magnesium-based composite material possesses a thermal conductivity ≥210 W / m·K and / or a linear thermal expansion coefficient of 18–25 ppm / K, which can, to a certain extent, adapt to the heat dissipation requirements of electronic devices, alleviate thermal stress mismatch problems, and improve application reliability.

[0016] The preparation method described in this application uses commercially available magnesium alloy sheets as the matrix material, which can avoid the risk of combustion and explosion during the preparation, storage, and use of magnesium powder from the source. Through the coordinated process of surface activation, diamond-coated stack assembly, vacuum-clad hot rolling, and subsequent heat treatment, the mechanical interlocking of diamond and matrix can be achieved through rolling plastic deformation, and the metallurgical bonding can be formed by promoting the diffusion of the interfacial coating through heat treatment, thereby reducing interfacial thermal resistance and improving thermal conductivity to a certain extent. This preparation method relies on mature rolling technology, and the process flow is simple and standardized, providing a feasible technical path for the large-scale production of high-performance magnesium-based thermal management composite materials. Detailed Implementation

[0017] To facilitate understanding by those skilled in the art, the present application will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present application.

[0018] As used herein, “and / or” includes all combinations of any one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used herein, the singular forms “a,” “an,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. Further understanding is needed; when used in this specification, “comprising” specifies the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0019] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, terms, as defined in commonly used dictionaries, are interpreted in accordance with their meaning in the context of the relevant field and are not idealized or overly formal, unless explicitly defined herein.

[0020] The exemplary invention described herein may suitably omit any one or more limiting elements, which are not specifically disclosed herein. Therefore, terms such as “comprising,” “including,” “containing,” etc., should be interpreted broadly and non-limitingly. Furthermore, the terminology used herein is for descriptive purposes without limitation, and it is unintentional to use terms that do not include any equivalent characteristics, but only to describe a subset of their characteristics; however, various modifications are possible within the scope of this application according to the claims. Therefore, while this application has been specifically disclosed through preferred embodiments and optional features, modifications disclosed herein to embody variations of this application may be noted by those skilled in the art, and such modifications and variations are considered to be within the scope of this application.

[0021] In existing technologies, the preparation of magnesium / diamond composite materials mainly employs powder metallurgy or gas pressure infiltration. Powder metallurgy involves mixing, pressing, and sintering; however, magnesium powder is highly reactive and prone to oxidation or even explosion, increasing safety risks and production costs, and reducing the interfacial bonding strength and thermal conductivity of the composite material. Gas pressure infiltration requires high-pressure conditions to infiltrate molten magnesium alloy, resulting in complex equipment, demanding processes, poor infiltration uniformity, susceptibility to defects, and low production efficiency, hindering its large-scale application. Furthermore, both methods present challenges in controlling interfacial reactions and optimizing microstructure, affecting the final performance of the composite material. Therefore, this application provides a magnesium-based composite material and its preparation method. This method eliminates the need for magnesium powder, directly using commercially available magnesium alloy sheets and employing a lamination rolling process to composite the magnesium alloy with coated diamond particles. The process is safe, simple, and easily industrialized.

[0022] A first aspect of this application provides a magnesium-based composite material comprising at least two magnesium alloy matrices and a reinforcing phase disposed between the two magnesium alloy matrices; The magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ≥ 210 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 25 ppm / K.

[0023] The magnesium-based composite material described in this application employs a layered structure with a multi-layered magnesium alloy matrix sandwiched with reinforcing phases. This structure helps to create a uniform thermal conductivity pathway while relying on the magnesium alloy matrix to ensure the overall mechanical properties of the material. This magnesium-based composite material possesses a thermal conductivity ≥210 W / m·K and / or a linear coefficient of thermal expansion of 18–25 ppm / K, which can, to a certain extent, meet the heat dissipation requirements of electronic devices, alleviate thermal stress mismatch problems, and improve application reliability.

[0024] In summary, the magnesium-based composite material of this application combines the lightweight properties of materials with the control of thermal properties, which helps to improve the stability and reliability of electronic equipment operation, and at the same time provides a feasible structural basis for the large-scale application of thermal management materials.

[0025] In some embodiments, the magnesium alloy matrix satisfies at least one of the following conditions: (1) Tensile strength is 200-300 MPa; (2) Yield strength is 150-200 MPa; (3) The elongation rate is 8-12%; (4) The magnesium alloy matrix includes a magnesium alloy sheet; The magnesium alloy sheet is an AZ31B or ZK60 rolled sheet, and the thickness of the magnesium alloy sheet is 0.5 mm to 1.0 mm.

[0026] Through the above embodiments, while ensuring that the magnesium alloy matrix has a good strength-plasticity match, it can adapt to the plastic deformation requirements of hot rolling process, which helps to uniformly press diamond particles into the matrix and tightly composite the layers. At the same time, it provides stable mechanical support for composite materials, reduces the risk of deformation and cracking during assembly and use to a certain extent, and adapts to the application scenarios of thermal management components.

[0027] In some embodiments, the tensile strength of the magnesium alloy matrix is ​​200–300 MPa; for example, the tensile strength of the magnesium alloy matrix can be 200 MPa, 220 MPa, 240 MPa, 260 MPa, 280 MPa, 300 MPa, or any combination thereof. The tensile strength of the magnesium alloy matrix provides a reliable mechanical load-bearing foundation for the composite material, helps improve the material's resistance to deformation during the assembly and operation of electronic devices, and meets the structural stability requirements of heat dissipation components. When the tensile strength of the magnesium alloy matrix is ​​controlled within the above range, the higher matrix strength can form a synergistic effect with the diamond reinforcement phase, which can alleviate the risk of cracking and deformation under external force and thermal stress to a certain extent, ensure the structural reliability of the thermal management components for long-term use, and also provide stable performance support for subsequent processing and practical applications.

[0028] In some embodiments, the yield strength of the magnesium alloy matrix is ​​150–200 MPa; for example, the yield strength of the magnesium alloy matrix can be 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, or any combination thereof. Controlling the yield strength of the magnesium alloy matrix within the above range can effectively improve the material's resistance to plastic deformation, adapt to the stress and deformation requirements during hot rolling, and reduce the risk of abnormal deformation during processing. Simultaneously, it can improve the structural stability of the finished composite material to a certain extent, alleviate the problem of permanent deformation under thermal stress and external forces, and ensure the reliability of thermal management components.

[0029] In some embodiments, the elongation of the magnesium alloy matrix is ​​8–12%; for example, the elongation of the magnesium alloy matrix can be 8%, 9%, 10%, 11%, 12%, or any combination thereof. Controlling the elongation of the magnesium alloy matrix within the above range enables it to possess excellent plastic deformation capacity, adapting to the large deformation requirements of hot rolling processes, reducing the risk of cracking defects during rolling, and facilitating the uniform pressing of diamond particles into the matrix to form a tight interlocking structure. Good plasticity can also buffer thermal stress and external impacts to a certain extent, improving the structural stability of the composite material during service.

[0030] In some embodiments, the magnesium alloy matrix comprises a magnesium alloy sheet; The magnesium alloy sheet is an AZ31B or ZK60 rolled sheet with a thickness of 0.5 mm to 1.0 mm. For example, the thickness of the magnesium alloy sheet can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, or any combination thereof. AZ31B or ZK60 rolled sheets are readily available, which avoids the safety risks associated with using magnesium powder from the source. Furthermore, their good strength and plasticity provide a stable mechanical basis for the composite material to a certain extent. Controlling the thickness of the magnesium alloy sheet within the above range allows for the adaptation to a laminated hot rolling process, which is beneficial for uniform plastic deformation of the matrix and ensures effective intercalation of diamond particles.

[0031] In some embodiments, the volume fraction of the reinforcing phase is 10% to 30% based on the volume of the composite material; for example, the volume fraction of the reinforcing phase can be 10%, 15%, 20%, 25%, 30%, or any combination thereof. When the volume fraction of the reinforcing phase is controlled within the above range, the high thermal conductivity of the diamond phase can be effectively utilized to improve the overall thermal conductivity of the composite material while ensuring the continuity of the magnesium alloy matrix structure. Simultaneously, the linear thermal expansion coefficient of the material is controlled, taking into account both interfacial bonding quality and mechanical properties, thus meeting the comprehensive application requirements of thermal management scenarios. Specifically, in step S2 (stack) of the preparation method, the volume fraction can be controlled by adjusting the areal density (particle mass per unit area) of the diamond particles on the activated surface of the magnesium alloy matrix.

[0032] In some embodiments, the reinforcing phase comprises diamond particles with a particle size of 10 μm to 50 μm. For example, the particle size of the diamond particles can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or any combination thereof. When the particle size of the diamond particles is controlled within the above range, uniform dispersion of particles can be achieved during the lamination process, reducing particle agglomeration. This facilitates the smooth pressing of particles into the magnesium alloy matrix during rolling, reduces the risk of interfacial stress concentration, and ensures the effective construction of thermal conductivity pathways. It balances interfacial bonding quality and thermal conductivity, meeting the process characteristics requirements of lamination rolling.

[0033] In some embodiments, the surface of the diamond particles is provided with a coating, the thickness of which is 0.5 μm to 1 μm; for example, the thickness of the coating can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm or any combination thereof; when the coating thickness is controlled within the above range, the interfacial compatibility between the diamond and the magnesium alloy matrix can be improved, the interfacial diffusion reaction during the heat treatment stage can be promoted to enhance the interfacial bonding strength, and the problems of limited effect due to excessively thin coating and reduced thermal conductivity due to excessively thick coating can be avoided, thereby reducing interfacial thermal resistance and ensuring the thermal conductivity and mechanical stability of the composite material.

[0034] In some embodiments, the coating includes any one of a titanium coating, a zirconium coating, or a chromium coating. Using a titanium, zirconium, or chromium coating as an intermediate layer helps improve the interfacial compatibility between diamond and the magnesium alloy matrix, promotes interfacial diffusion reactions during heat treatment, enhances interfacial bonding strength, and reduces interfacial thermal resistance, thus playing a positive role in ensuring the thermal conductivity and mechanical stability of the composite material.

[0035] Furthermore, this application pre-coats an active metal layer (such as Ti or Zr) on the diamond surface and combines this with high-temperature heat treatment (500°C to 550°C) after rolling, promoting a full reaction between the coating and the magnesium matrix to generate carbides (such as TiC or ZrC). This in-situ generated carbide layer acts as an "interface bridge," transforming the bonding between the diamond and the magnesium matrix from mechanical interlocking to a strong and tough metallurgical bond, effectively reducing interfacial thermal resistance and fully utilizing the high thermal conductivity potential of diamond.

[0036] In some embodiments, the magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ranges from 210 W / (m·K) to 305 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 22 ppm / K.

[0037] Through the above embodiments, magnesium-based composite materials can meet the heat dissipation requirements of high-power electronic devices and improve thermal management efficiency; and / or, magnesium-based composite materials can match the thermal expansion characteristics of most electronic components, alleviate thermal stress mismatch problems, and ensure the stability and reliability of electronic equipment operation.

[0038] In some embodiments, the thermal conductivity of the magnesium-based composite material is ≥210 W / (m·K), preferably, the thermal conductivity of the magnesium-based composite material is between 210 W / (m·K) and 305 W / (m·K); for example, the thermal conductivity of the magnesium-based composite material can be 210 W / (m·K), 220 W / (m·K), 240 W / (m·K), 250 W / (m·K), 280 W / (m·K), 305 W / (m·K) or any combination thereof; after adjusting the thermal conductivity of the magnesium-based composite material to the above range, its thermal conductivity is significantly improved compared with conventional magnesium alloys, which can meet the high-efficiency heat dissipation requirements of high-power electronic devices to a certain extent. Combined with the advantage of low density of magnesium matrix, it helps to achieve a balance between lightweight thermal management components and heat dissipation performance.

[0039] In some embodiments, the linear thermal expansion coefficient of the magnesium-based composite material is 18–25 ppm / K, preferably 18–22 ppm / K. For example, the linear thermal expansion coefficient of the magnesium-based composite material can be 18 ppm / K, 19 ppm / K, 20 ppm / K, 21 ppm / K, 22 ppm / K, or any combination thereof. Adjusting the linear thermal expansion coefficient of the magnesium-based composite material to the above range can alleviate the thermal stress mismatch problem caused by temperature fluctuations to a certain extent, reduce the risk of interface cracking and structural deformation, and help improve the stability and reliability of electronic equipment operation.

[0040] A second aspect of this application provides a method for preparing the magnesium-based composite material described above, comprising the following steps: S1. Magnesium alloy matrix pretreatment The surfaces of the magnesium alloy substrates to be composited, consisting of at least two layers, are activated to remove the oxide film on the surface of the magnesium alloy substrates, forming an activated surface and thus obtaining an activated magnesium alloy substrate. S2. Stacking Diamond particles with a coating are obtained, and the diamond particles are evenly distributed on the activated surface of the activated magnesium alloy matrix. Then, multiple layers of magnesium alloy matrix are stacked to form a stacked blank with alternating layers of "magnesium alloy matrix-diamond particles-magnesium alloy matrix". S3. Encapsulation The laminated blank is placed in a sleeve, vacuumed, and then sealed. S4. Hot-rolled composite The sealed casing is heated and then rolled to cause plastic deformation of the magnesium alloy matrix, press diamond particles into the magnesium alloy matrix, and connect the multiple layers of magnesium alloy matrix through diamond particles to obtain a rolled composite plate. S5. Heat Treatment The rolled composite plate is heat-treated to promote the diffusion reaction between the metal coating on the surface of the diamond particles and the magnesium alloy matrix, forming a good interfacial metallurgical bond.

[0041] In the aforementioned technical solution, the preparation method uses commercially available magnesium alloy sheets as the matrix material, thus avoiding the risks of combustion and explosion during the preparation, storage, and use of magnesium powder. Through the coordinated processes of surface activation, diamond lamination assembly, vacuum-clad hot rolling, and subsequent heat treatment, mechanical integration between the diamond and the matrix is ​​achieved through rolling plastic deformation, while heat treatment promotes the diffusion of the interfacial coating to form a metallurgical bond, thereby reducing interfacial thermal resistance and improving thermal conductivity to a certain extent. This preparation method relies on mature rolling technology, with a simple and standardized process flow, providing a feasible technical path for the large-scale production of high-performance magnesium-based thermal management composite materials.

[0042] In some embodiments, the activation treatment in step S1 includes mechanical polishing and chemical activation; preferably, after the activation treatment, a copper or nickel interlayer is pre-plated on the surface to be laminated. The surface treatment method combining mechanical polishing and chemical activation can effectively remove the oxide film on the surface of the magnesium alloy sheet to be laminated, obtaining a clean, fresh activated surface, increasing surface energy, and helping to enhance the interfacial bonding effect in the subsequent lamination process. The pre-plating of a copper or nickel interlayer after activation can, to a certain extent, block air and delay surface re-oxidation, while optimizing interfacial compatibility, promoting interfacial diffusion bonding during rolling and heat treatment stages, which helps to reduce interfacial thermal resistance and improve the bonding strength and thermal conductivity stability of the composite material.

[0043] Furthermore, the specific process of mechanical polishing is as follows: The surface of the magnesium alloy sheet to be laminated is polished with sandpaper in successive steps until a uniform metallic luster is exposed, thoroughly removing the original oxide film, oil, and surface contaminants to obtain a clean and fresh metal surface. After polishing, the chemical activation process is immediately carried out to prevent the exposed magnesium surface from oxidizing again in the air.

[0044] Furthermore, the specific process of chemical activation is as follows: Chemical activation was performed using a phosphoric acid-ethanol system: 85% analytical grade phosphoric acid was mixed with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%; the temperature of the activation solution was controlled at 25℃, and the mechanically polished magnesium plate was immediately immersed in the activation solution for 30s to 60s; after removal, the surface was quickly dried with cold air, and the subsequent lamination process had to be carried out within 30 minutes to prevent the formation of an oxide film on the freshly activated surface.

[0045] In some embodiments, the sheath mentioned in step S3 is a stainless steel sheath. Using a stainless steel sheath to encapsulate the laminated billet can maintain a stable internal vacuum environment after vacuum sealing, helping to reduce the risk of oxidation of the magnesium alloy matrix and diamond interface during heating and rolling. Stainless steel possesses both good high-temperature strength and deformation compliance, which can form uniform constraints on the internal billet, ensuring the stability of the composite process to a certain extent and improving the quality of interface bonding.

[0046] Specifically, in step S3, the vacuum level is lower than 10 during the vacuuming process. -2 Pa, for example, evacuating the inner casing to 5 × 10 Pa. -2 Pa is then sealed by welding. Through vacuum treatment, the air inside the cladding can be discharged, preventing oxidation of the magnesium alloy matrix and diamond interface during heating and rolling. At the same time, the cladding fits tightly against the billet, ensuring uniform transmission of rolling pressure and improving the quality of interface composite.

[0047] In some embodiments, step S4 satisfies at least one of the following conditions: (1) The heating temperature is 350°C to 400°C; (2) The rolling process is a multi-pass rolling process; in the first pass of the multi-pass rolling process, the reduction rate is 30% to 50%.

[0048] The above embodiments help improve the plasticity of magnesium alloys, reduce deformation resistance, promote the uniform pressing of diamond particles into the matrix, enhance the interlayer interlocking effect, and also refine the matrix grains and reduce interface defects to a certain extent, providing a process basis for the stable molding of composite materials and subsequent interface reactions.

[0049] In some embodiments, the heating temperature in step S4 is 350°C to 400°C; for example, the heating temperature can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, or a range of any two thereof. Heating within this temperature range can significantly improve the plastic deformation performance of magnesium alloy sheets and reduce rolling deformation resistance, thereby promoting fully uniform plastic deformation of the magnesium matrix, allowing diamond particles to be smoothly embedded in the matrix, and enhancing the density and uniformity of the interlayer composite. This temperature range can effectively reduce the risk of sheet cracking caused by low temperatures, while avoiding the problems of coarse matrix grains and performance degradation caused by high temperatures, ensuring the stability of rolling forming, and laying a technological foundation for subsequent interfacial diffusion reactions and the comprehensive performance of composite materials.

[0050] In some embodiments, in step S4, the rolling is a multi-pass rolling; in the first pass of the multi-pass rolling, the reduction rate is 30% to 50%. For example, multi-pass rolling includes 2-pass rolling, 3-pass rolling, 4-pass rolling, or 5-pass rolling; for example, the reduction rate can be 30%, 35%, 40%, 45%, 50%, or any combination thereof; when the rolling process is controlled to the above range, it helps to promote sufficient and uniform plastic deformation of the magnesium alloy sheet, so that diamond particles can be effectively pressed into the matrix surface, strengthening the mechanical interlocking effect between layers, refining the magnesium alloy matrix grains to a certain extent, reducing composite interface defects, improving the uniformity of interlayer bonding, and facilitating the uniformity of interface diffusion reaction during subsequent heat treatment, thus providing process support for the composite material to obtain stable thermal conductivity and mechanical properties.

[0051] In some embodiments, the heat treatment in step S5 satisfies at least one of the following conditions: (1) The temperature of the heat treatment is 500℃ to 550℃; (2) The heat treatment holding time is 1 to 4 hours; (3) The heat treatment is carried out under vacuum or protective atmosphere.

[0052] By employing the above technical solutions, selecting appropriate temperatures and holding times can promote tissue homogenization, while vacuum or protective atmospheres can reduce oxidation, providing a more stable material basis for subsequent processing or use to a certain extent, and helping to improve the overall performance of magnesium-based composite materials.

[0053] In some embodiments, in step S5, the heat treatment temperature is between 500°C and 550°C. For example, the heat treatment temperature can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or any combination thereof. Under the heat treatment control that meets the above conditions, the interfacial atomic diffusion between the metal coating on the diamond particle surface and the magnesium alloy matrix can be effectively promoted, forming a stable metallurgical bonding interface, eliminating interfacial gaps and microscopic defects, significantly reducing interfacial thermal resistance, and ensuring the continuity of the heat conduction path and heat transfer efficiency. At the same time, this temperature range can optimize the microstructure uniformity of the magnesium alloy matrix, alleviate the interfacial stress concentration between diamond and the matrix, and improve the interfacial bonding strength and material structural stability. It can avoid the problems of insufficient interfacial diffusion and poor bonding effect caused by excessively low temperature, and also prevent defects such as overheating of the matrix and excessive generation of harmful phases at the interface caused by excessively high temperature, thus taking into account both the thermal conductivity and mechanical reliability of the composite material.

[0054] In some embodiments, the heat treatment holding time in step S5 is set to 1 to 4 hours (e.g., 1h, 2h, 3h, 4h, or any range thereof). This holding time range can promote sufficient atomic diffusion, ensure uniform distribution of alloying elements, reduce segregation, and thus improve the strength and toughness of the material, providing more stable performance support for subsequent processing and applications.

[0055] In some embodiments, the heat treatment in step S5 needs to be carried out in a vacuum or protective atmosphere to avoid direct contact between the magnesium alloy and air at high temperatures, effectively reducing the probability of side reactions such as oxidation and nitriding, thereby ensuring the stability of material properties.

[0056] Test methods and equipment: Testing the thermal conductivity of magnesium-based composite materials: The thermal conductivity of magnesium-based composite materials was tested using the laser scintillation method. The test method is as follows: After processing the sample into standard discs and performing surface treatment, the thermal diffusivity was measured using a laser flare instrument, and the density and specific heat capacity were simultaneously determined. The thermal conductivity was then calculated using a formula. Specifically, the composite material was processed into discs with a diameter of 12.7 mm and a thickness of 2 mm. After double-sided polishing, a graphite coating was sprayed onto the discs. The discs were then placed in an LFA testing instrument, and the front side of the sample was heated with a pulsed laser under inert gas protection. The temperature rise curve of the back side was recorded by an infrared detector, and the thermal diffusivity α was obtained by fitting the curve. At the same time, the density ρ and the specific heat capacity Cp of the composite material were measured, and the thermal conductivity of the single sample was calculated using the formula λ=α×Cp×ρ.

[0057] The thermal conductivity of the magnesium-based composite material was obtained by averaging the test results of the three sets of parallel samples.

[0058] Testing of the linear thermal expansion coefficient of magnesium-based composite materials: The linear thermal expansion coefficient of magnesium-based composite materials was tested using a push-rod thermal dilatometer. The test method is as follows: The sample is processed into a regular strip shape, and the length change is recorded under programmed temperature rise. The average linear thermal expansion coefficient within the test range is calculated using a formula. Specifically, the composite material is processed into a 20 mm long strip sample, ensuring that both ends are parallel. It is placed in a thermal expansion apparatus, heated at a set rate under inert gas protection, and the initial length L of the sample is recorded simultaneously. D Temperature change ΔT and corresponding length change ΔL; According to the formula K = ΔL / (L) D Calculate the average linear thermal expansion coefficient of a single sample within the test temperature range using ×ΔT).

[0059] The average value of the test results of the three sets of parallel samples was then used to obtain the linear thermal expansion coefficient of the magnesium-based composite material.

[0060] Testing the tensile strength of magnesium alloy matrix: The tensile strength of magnesium alloy matrix was tested using a room temperature tensile test method. The test method involved preparing a plate-shaped tensile specimen along the rolling direction, loading it onto a universal testing machine until fracture, recording the maximum test force, and calculating the tensile strength using a formula.

[0061] Specifically, this includes: cutting rectangular cross-sectional plate-shaped specimens along the rolling direction of the magnesium alloy sheet, and calibrating the original cross-sectional area S of the parallel section of the specimen. D The sample is clamped on an electronic universal testing machine and subjected to uniform loading at a set rate at room temperature until it breaks. The maximum test force Fm is recorded throughout the process. According to the formula Rm = Fm / S D Calculate the tensile strength of a single sample.

[0062] Then, the average value of the test results of the three sets of parallel samples was taken to obtain the tensile strength of the magnesium alloy matrix.

[0063] Testing of yield strength of magnesium alloy matrix: The yield strength of magnesium alloy matrix was tested using a room temperature tensile test. The test method involved preparing a plate-shaped tensile specimen along the rolling direction, collecting strain data with an extensometer, and using the specified plastic elongation strength as the yield strength index.

[0064] Specifically, this includes: cutting rectangular cross-sectional plate-shaped specimens along the rolling direction of the magnesium alloy sheet, and calibrating the original cross-sectional area S of the parallel section of the specimen. D The sample is clamped in an electronic universal testing machine and equipped with a contact extensometer. A uniform loading force is applied at room temperature. When the plastic elongation of the sample reaches 0.2%, the corresponding test force F is recorded. The force is then calculated using the formula R = F / S. D Calculate the yield strength of a single sample.

[0065] The yield strength of the magnesium alloy matrix was obtained by averaging the test results of the three sets of parallel samples.

[0066] Testing the elongation of magnesium alloy matrix: The elongation of magnesium alloy matrix was tested using a room temperature tensile test. The test method involved measuring the gauge length after fracture of the tensile specimen and calculating the elongation after fracture by the difference between the gauge length after fracture and the original gauge length.

[0067] Specifically, this includes: marking the original gauge length L on the parallel section of the tensile specimen. D After the specimen breaks, the two sections of the specimen are tightly aligned and fitted together along the cross-section, and the gauge length L after the break is measured. u According to the formula A=(L u -L D ) / L D Calculate the elongation rate of a single sample after fracture by multiplying by 100%.

[0068] Then, the average value of the test results of the three sets of parallel samples was taken to obtain the elongation of the magnesium alloy matrix. Example 1

[0069] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: Commercially available AZ31B magnesium alloy sheet with a thickness of 0.8 mm was selected and cut into 200 mm × 100 mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 200 MPa, 150 MPa, and 8%, respectively. Titanium-plated diamond particles with an average particle size of 30μm and a surface coated with a titanium layer of 1μm thickness were selected.

[0070] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until it reveals a metallic luster, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25°C and the activation time is 45 seconds. After removal, it is quickly dried with cold air to obtain the activated magnesium alloy substrate.

[0071] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and titanium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.02 g / cm³. 2 Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0072] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3 After Pa, the sealing sleeve is welded.

[0073] S4. Hot rolling: The cladding is heated to 380℃ and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 40%, followed by three passes of rolling, resulting in a rolled composite plate with a thickness of approximately 1.0 mm.

[0074] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 520°C under vacuum, hold it for 2 hours, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material. Example 2

[0075] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: Commercially available AZ31B magnesium alloy sheet with a thickness of 0.5 mm was selected and cut into 200 mm × 100 mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 200 MPa, 150 MPa, and 8%, respectively. Titanium-plated diamond particles with an average particle size of 10 μm and a surface coated with a titanium layer of 0.5 μm thickness were selected.

[0076] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until the metallic luster is exposed, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25°C and the activation time is 30 seconds. After removal, it is quickly dried with cold air to obtain the activated magnesium alloy substrate.

[0077] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and titanium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.015 g / cm³. 2 Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0078] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3 After Pa, the sealing sleeve is welded.

[0079] S4. Hot rolling: The cladding is heated to 350°C and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 30%, followed by two passes of rolling, resulting in a rolled composite plate with a thickness of approximately 0.9 mm.

[0080] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 500°C under vacuum, hold it for 1 hour, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material. Example 3

[0081] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: Commercially available AZ31B magnesium alloy sheet with a thickness of 1 mm was selected and cut into 200 mm × 100 mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 200 MPa, 150 MPa, and 8%, respectively. Titanium-plated diamond particles with an average particle size of 50 μm and a surface coated with a titanium layer of 0.8 μm thickness were selected.

[0082] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until the metallic luster is exposed, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25°C and the activation time is 60 seconds. After removal, it is quickly dried with cold air to obtain the activated magnesium alloy substrate.

[0083] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and titanium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.03 g / cm³. 2Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0084] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3 After Pa, the sealing sleeve is welded.

[0085] S4. Hot rolling: The cladding is heated to 400℃ and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 50%, followed by 5 passes of rolling, resulting in a rolled composite plate with a thickness of approximately 1.0 mm.

[0086] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 550°C under vacuum, hold it for 4 hours, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material. Example 4

[0087] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: A 0.7mm thick ZK60 magnesium alloy sheet was selected and cut into 200mm × 100mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 300MPa, 200MPa, and 12%, respectively. Zirconium-plated diamond particles with an average particle size of 20μm and a 0.6μm thick zirconium layer on the surface were selected.

[0088] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until it reveals a metallic luster, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25°C and the activation time is 45 seconds. After removal, it is quickly dried with cold air to obtain the activated magnesium alloy substrate.

[0089] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and zirconium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.02 g / cm³. 2 Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0090] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3After Pa, the sealing sleeve is welded.

[0091] S4. Hot rolling: The cladding is heated to 380℃ and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 40%, followed by 2-3 passes, resulting in a rolled composite plate with a thickness of approximately 1.0 mm.

[0092] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 520°C under vacuum, hold it for 2 hours, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material. Example 5

[0093] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: A 0.9mm thick ZK60 magnesium alloy sheet was selected and cut into 200mm × 100mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 300MPa, 200MPa, and 12%, respectively. Chromium-plated diamond particles with an average particle size of 40μm and a 0.8μm thick chromium layer on the surface were selected.

[0094] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until it reveals a metallic luster, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25°C and the activation time is 45 seconds. After removal, it is quickly dried with cold air to obtain the activated magnesium alloy substrate.

[0095] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and chromium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.025 g / cm³. 2 Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0096] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3 After Pa, the sealing sleeve is welded.

[0097] S4. Hot rolling: The cladding is heated to 380℃ and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 40%, followed by three passes of rolling, resulting in a rolled composite plate with a thickness of approximately 1.0 mm.

[0098] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 520°C under vacuum, hold it for 2 hours, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material. Example 6

[0099] A method for preparing a magnesium-based composite material includes the following steps: S1. Raw material preparation and pretreatment: Commercially available AZ31B magnesium alloy sheet with a thickness of 0.8 mm was selected and cut into 200 mm × 100 mm sheets to obtain the magnesium alloy matrix. The tensile strength, yield strength, and elongation of the magnesium alloy matrix were 200 MPa, 150 MPa, and 8%, respectively. Titanium-plated diamond particles with an average particle size of 30μm and a surface coated with a titanium layer of 1μm thickness were selected.

[0100] Mix 85% analytical grade phosphoric acid with anhydrous ethanol to prepare an activation solution with a phosphoric acid volume fraction of 20%. The surface of the magnesium alloy substrate to be laminated is sanded until a metallic luster is exposed, and then immediately immersed in a phosphoric acid-ethanol solution for chemical activation. The activation temperature is controlled at 25℃ and the activation time is 45 seconds. After removal, it is quickly dried with cold air, and then chemical copper plating is performed (the main components of the plating solution are 12g / L copper sulfate, 12mL / L formaldehyde, and 15g / L disodium EDTA complexing agent, with the pH adjusted to 12-13 using sodium hydroxide, and the remainder being deionized water). The reaction is carried out at 60℃ for 15 minutes to deposit a copper layer with a thickness of 0.8μm. After removal and drying, the activated magnesium alloy substrate is obtained.

[0101] S2. Layering and spreading: In an argon-filled glove box, the activated magnesium alloy substrate is laid flat, and titanium-plated diamond particles are evenly dispersed on the surface using a spraying method, controlling the diamond surface density to be approximately 0.02 g / cm³. 2 Then another activated magnesium plate is placed on top, forming a "sandwich" structure of "magnesium plate-diamond-magnesium plate" to obtain a laminated blank.

[0102] S3. Package: The laminated blanks are placed in a stainless steel sheath and vacuumed to 5×10. -3 After Pa, the sealing sleeve is welded.

[0103] S4. Hot rolling: The cladding is heated to 380℃ and held for 45 minutes. Then it is rolled on a two-roll mill with a first pass reduction of 40%, followed by three passes of rolling, resulting in a rolled composite plate with a thickness of approximately 1.0 mm.

[0104] S5. Heat treatment: Remove the cladding, place the rolled composite plate in a vacuum heat treatment furnace, heat it to 520°C under vacuum, hold it for 2 hours, and then cool it to room temperature with the furnace to obtain a magnesium-based composite material.

[0105] Comparative Example 1: A method for preparing a magnesium-based composite material, comprising the following steps: In step S1, diamond particles without a surface coating are used. The remaining conditions are the same as in Example 1.

[0106] Comparative Example 2: A method for preparing a magnesium-based composite material, comprising the following steps: The surface density of the diamond in step S1 is 0.007 g / cm³. 2 ; The remaining conditions are the same as in Example 1.

[0107] Comparative Example 3: A method for preparing a magnesium-based composite material, comprising the following steps: The surface density of the diamond in step S1 is 0.05 g / cm³. 2 ; The remaining conditions are the same as in Example 1.

[0108] Comparative Example 4: A method for preparing a magnesium-based composite material, comprising the following steps: In step S4, the heating temperature is 300°C; The remaining conditions are the same as in Example 1.

[0109] Comparative Example 5: A method for preparing a magnesium-based composite material, comprising the following steps: In step S4, the heating temperature is 500°C; The remaining conditions are the same as in Example 1.

[0110] Comparative Example 6: A method for preparing a magnesium-based composite material, comprising the following steps: In step S5, the heating temperature is 400°C; The remaining conditions are the same as in Example 1.

[0111] Comparative Example 7: A method for preparing a magnesium-based composite material, comprising the following steps: In step S5, the heating temperature is 630°C; The remaining conditions are the same as in Example 1.

[0112] The preparation parameters and test results for each embodiment and comparative example are shown in Table 1.

[0113] Table 1

[0114] Examples and comparative examples are provided to illustrate the implementation methods of this application in more detail. Those skilled in the art will understand that the preparation methods described in this application are merely examples, and any other suitable preparation methods are within the scope of this application. Unless otherwise specified, the raw materials used in the following examples are all from common commercially available products, and the apparatus or equipment used are all purchased from conventional commercial sales channels. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are based on mass.

Claims

1. A magnesium-based composite material, characterized by, It includes at least two magnesium alloy substrates and a reinforcing phase disposed between the two magnesium alloy substrates; The magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ≥ 210 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 25 ppm / K.

2. The magnesium-based composite of claim 1, wherein, The magnesium alloy matrix satisfies at least one of the following conditions: (1) Tensile strength is 200-300 MPa; (2) Yield strength is 150-200 MPa; (3) The elongation rate is 8-12%; (4) The magnesium alloy matrix includes a magnesium alloy sheet; The magnesium alloy sheet is an AZ31B or ZK60 rolled sheet, and the thickness of the magnesium alloy sheet is 0.5 mm to 1.0 mm.

3. The magnesium-based composite of claim 1, wherein, Based on the volume of the composite material, the volume fraction of the reinforcing phase is 10% to 30%. Preferably, the reinforcing phase comprises diamond particles with a particle size of 10 μm to 50 μm.

4. The magnesium-based composite of claim 3, wherein, The surface of the diamond particle is coated with a coating having a thickness of 0.5 μm to 1 μm; Preferably, the coating includes any one of a titanium coating, a zirconium coating, or a chromium coating.

5. The magnesium-based composite of claim 1, wherein, The magnesium-based composite material satisfies at least one of the following conditions: (1) Thermal conductivity ranges from 210 W / (m·K) to 305 W / (m·K); (2) The linear thermal expansion coefficient is 18 to 22 ppm / K.

6. The method of producing a magnesium-based composite material according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Magnesium alloy matrix pretreatment The surfaces of the magnesium alloy substrates to be composited, consisting of at least two layers, are activated to remove the oxide film on the surface of the magnesium alloy substrates, forming an activated surface and thus obtaining an activated magnesium alloy substrate. S2. Stacking Diamond particles with a coating are obtained, and the diamond particles are evenly distributed on the activated surface of the activated magnesium alloy matrix. Then, multiple layers of magnesium alloy matrix are stacked to form a stacked blank with alternating "magnesium alloy matrix-diamond particles-magnesium alloy matrix". S3. Encapsulation The laminated blank is placed in a sleeve, vacuumed, and then sealed. S4. Hot-rolled composite The sealed casing is heated and then rolled to cause plastic deformation of the magnesium alloy matrix, press diamond particles into the magnesium alloy matrix, and connect the multiple layers of magnesium alloy matrix through diamond particles to obtain a rolled composite plate. S5. Heat Treatment The rolled composite plate is heat-treated to promote the diffusion reaction between the metal coating on the surface of the diamond particles and the magnesium alloy matrix, forming a good interfacial metallurgical bond.

7. The production method according to claim 6, wherein The activation treatment described in step S1 includes mechanical polishing and chemical activation; Preferably, after the activation treatment, a copper interlayer or a nickel interlayer is pre-plated on the surface to be composited.

8. The preparation method according to claim 6, characterized in that, The sleeve mentioned in step S3 is a stainless steel sleeve.

9. The preparation method according to claim 6, characterized in that, Step S4 satisfies at least one of the following conditions: (1) The heating temperature is 350°C to 400°C; (2) The rolling process is a multi-pass rolling process; in the first pass of the multi-pass rolling process, the reduction rate is 30% to 50%.

10. The method of claim 6, wherein, The heat treatment described in step S5 satisfies at least one of the following conditions: (1) The temperature of the heat treatment is 500℃ to 550℃; (2) The heat treatment holding time is 1 to 4 hours; (3) the heat treatment is performed under vacuum or in a protective atmosphere.

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