Magnesium alloy composite material, method for preparing the same and use thereof

Abstract

The embodiment of the application provides a magnesium alloy composite material and a preparation method and application thereof, the magnesium alloy composite material comprises magnesium alloy base body constituent elements, nonmetal heat-conducting particles and heat-conducting metal elements, the nonmetal heat-conducting particles are dispersedly distributed in the magnesium alloy composite material; the magnesium alloy base body constituent elements comprise 87.5%-95% of Mg, 4%-10% of Zn, 0.05%-1% of Al, 0.05%-2% of La and Ce in total and ≤0.2% of inevitable impurities according to 100% of total mass. The magnesium alloy composite material is prepared by selecting an alloy base body with a specific component ratio, simultaneously introducing nonmetal heat-conducting particles and heat-conducting metal elements, and under the synergistic effect of various components, the magnesium alloy composite material has high heat conductivity, good formability and high yield strength.

Description

Technical Field

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

[0002] Magnesium alloys are highly favored in fields such as communications, 3C products, new energy vehicles, and aerospace due to their lightweight and high strength. However, with the continuous development of various device products, the requirements for the thermal conductivity and formability of magnesium alloys are constantly increasing. Taking optical communication devices as an example, with the soaring data transmission rates and the sharp increase in power density, devices are required to have excellent heat dissipation capabilities. At the same time, the trend of miniaturization and the need for highly integrated internal layouts further require their shells and other structural components to have complex structural characteristics such as ultra-thin wall designs and extremely small draft angles. Therefore, the thermal conductivity and formability of magnesium alloys used to manufacture the shells and other structural components of optical communication devices are challenged.

[0003] However, the low thermal conductivity of common commercial magnesium alloys, such as AZ91D (approximately 51 W / m·K after die casting), significantly limits their application in fields with high heat dissipation requirements. While some magnesium alloys with improved thermal conductivity (such as ZK60) are prone to hot cracking and therefore unsuitable for near-net-shape forming processes like die casting, they can only be used after deformation processing, making it difficult to meet the near-net-shape forming requirements of complex structural parts. Overall, most magnesium alloy materials currently used in the industry have relatively low thermal conductivity (thermal conductivity λ≤120 W / m·K), which contradicts their die casting formability. Therefore, developing a new magnesium alloy material that combines high thermal conductivity with good formability is essential. Summary of the Invention

[0004] In view of this, the present application provides a magnesium alloy composite material, its preparation method and application. The magnesium alloy composite material is made by selecting an alloy matrix with a specific component ratio and introducing non-metallic thermally conductive particles and thermally conductive metal elements. Under the synergistic effect of the components, the magnesium alloy composite material has high thermal conductivity, good formability and high yield strength.

[0005] The first aspect of this application provides a magnesium alloy composite material, which includes magnesium alloy matrix elements, non-metallic thermally conductive particles, and thermally conductive metallic elements, wherein the non-metallic thermally conductive particles are dispersed inside the magnesium alloy composite material.

[0006] The magnesium alloy matrix comprises, by total mass, 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities.

[0007] The magnesium alloy composite material provided in this application includes alloy matrix elements in a specific ratio, as well as non-metallic thermally conductive particles and thermally conductive metallic elements introduced into the magnesium alloy composite material. Through the synergistic effect of these components, the magnesium alloy composite material possesses high thermal conductivity, good formability, and high yield strength. Specifically, the specific composition and ratio of magnesium alloy matrix elements enable the magnesium alloy matrix itself to have high thermal conductivity and a good semi-solid forming process range, allowing for the formation of an excellent semi-solid spherical crystal microstructure. The magnesium alloy matrix elements include a suitable amount of Zn to form a Mg-Zn main system magnesium alloy, which is beneficial for improving the strength and hardness of the magnesium alloy, enhancing corrosion resistance, improving processing and forming performance, and reducing the tendency for hot cracking. A suitable amount of Al can further lower the liquidus temperature and improve the semi-solid formability. Suitable amounts of La (lanthanum) and Ce (cerium) can form Al with Al. 11 La3, Al 11 The Ce3 phase reduces the solid solution effect of Al in Mg, decreases lattice distortion, and improves the thermal conductivity and mechanical properties of magnesium alloys. Simultaneously, the higher magnesium content enables the magnesium alloy composite to maintain a high yield strength. Furthermore, the introduction of non-metallic thermally conductive particles and thermally conductive metallic elements into the magnesium alloy composite can effectively enhance its thermal conductivity.

[0008] In this embodiment of the application, the ratio of the mass percentage of Al to the sum of the mass percentages of La and Ce in the magnesium alloy matrix is ​​1:(1-15). This suitable ratio control can better balance the semi-solid forming performance and thermal conductivity of the magnesium alloy composite material.

[0009] In this embodiment of the application, the constituent elements of the magnesium alloy matrix also include one or more of Y, Mn, Sn, Gd, Ca, and Zr. Introducing these elements can further improve the performance of the magnesium alloy composite material.

[0010] In this embodiment, the mass percentage of non-metallic thermally conductive particles in the magnesium alloy composite material is 5%-30%. Controlling the total mass percentage of non-metallic thermally conductive particles within a suitable range facilitates uniform dispersion of these particles in the magnesium alloy matrix, preventing agglomeration and entanglement. This maximizes the role of the non-metallic thermally conductive particles in improving the thermal conductivity and strength of the magnesium alloy composite material. Simultaneously, it better controls the brittleness of the magnesium alloy composite material at a lower level, thereby enhancing the reliability of the structural components formed from the magnesium alloy composite material.

[0011] In this embodiment of the application, the mass percentage of thermally conductive metal elements in the magnesium alloy composite material is 0.1%-6%. The introduction of an appropriate amount of thermally conductive metal elements can promote the uniform dispersion of non-metallic thermally conductive particles in the magnesium alloy matrix during the preparation of the magnesium alloy composite material. It can also react in situ with the magnesium alloy matrix to generate an appropriate amount of first intermetallic compound, improving the interfacial bonding between the non-metallic thermally conductive particles and the magnesium alloy matrix. This allows for the addition of more non-metallic thermally conductive particles to the magnesium alloy composite material and achieves uniform dispersion, thereby improving the thermal conductivity of the magnesium alloy composite material. Furthermore, it avoids the negative impacts of excessive thermally conductive metal elements on the magnesium alloy composite material, such as increased weight and weakened mechanical properties.

[0012] In this embodiment, the mass ratio of the non-metallic thermally conductive particles to the thermally conductive metal element is (2-12):1. A suitable mass ratio is beneficial for better utilizing the synergistic effect of the non-metallic thermally conductive particles and the thermally conductive metal element to improve the thermal conductivity of the magnesium alloy composite material and to achieve a uniform dispersion of the non-metallic thermally conductive particles within the magnesium alloy composite material.

[0013] In this embodiment of the application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 5%-20%, and the mass percentage of the constituent elements of the magnesium alloy matrix is ​​80%-95%. This allows for a better balance of the mechanical properties, thermal conductivity, and processing performance of the magnesium alloy composite material.

[0014] In this embodiment, the non-metallic thermally conductive particles include one or more of aluminum nitride particles, graphite particles, diamond particles, and graphene particles. These non-metallic thermally conductive particles possess high thermal conductivity and high strength, which is beneficial for improving the thermal conductivity and strength of magnesium alloy composite materials.

[0015] In this embodiment, the thermally conductive metal element includes one or more metal elements that, when introduced individually or jointly into the magnesium alloy composite material, result in a magnesium lattice volume change of less than 5% and have a higher thermal conductivity than magnesium. Using an element that minimizes the magnesium lattice volume change (i.e., lattice distortion) helps reduce the negative impacts of lattice distortion caused by its introduction, such as a decrease in material thermal conductivity.

[0016] In this embodiment, the particle size of the non-metallic thermally conductive particles is 1μm-150μm. Controlling the particle size of the non-metallic thermally conductive particles within a suitable range is beneficial for the uniform dispersion of the non-metallic thermally conductive particles within the magnesium alloy composite material, and also helps to better improve the strength and hardness of the magnesium alloy composite material.

[0017] In this embodiment of the application, the thermally conductive metal element includes one or more of nickel, copper, aluminum, silver, and zinc. The thermally conductive metal element powder can be a pure metal powder (i.e., elemental powder) containing one thermally conductive metal element, or it can be an alloy powder containing two or more thermally conductive metal elements.

[0018] In this embodiment, at least a portion of the thermally conductive metal elements and the constituent elements of the magnesium alloy matrix form a first intermetallic compound; at least a portion of the first intermetallic compound is distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles. The first intermetallic compound distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles can improve the interfacial bonding between the magnesium alloy matrix and the non-metallic thermally conductive particles, which were originally neither reactive nor wettable.

[0019] In this embodiment, the magnesium alloy composite material includes a secondary α-Mg phase and a primary α-Mg phase dispersed within the secondary α-Mg phase. The primary α-Mg phase refers to the magnesium matrix phase that first precipitates from the liquid phase during the solidification process of the magnesium alloy. The secondary α-Mg phase is the magnesium matrix phase that subsequently precipitates during the growth process after the formation of the primary α-Mg phase.

[0020] In this embodiment, the particle size of the primary α-Mg phase is 10μm-100μm. These large-particle primary α-Mg phases can jointly construct heat conduction pathways through the synergistic effect of non-metallic thermally conductive particles and the first intermetallic compound, thereby bringing about high strengthening efficiency of the non-metallic thermally conductive particle-reinforced phase and better enabling the magnesium alloy composite material to have both excellent lightweight and ultra-high thermal conductivity.

[0021] In this embodiment of the application, the area ratio of the primary α-Mg phase in any cross-section of the magnesium alloy composite material is 5%-50%. The presence of a suitable amount of primary α-Mg phase is beneficial to improving the thermal conductivity of the magnesium alloy material, while also taking into account other excellent properties such as good mechanical properties.

[0022] In this embodiment of the application, the particle size of the secondary α-Mg phase is greater than or equal to 1 μm and less than 10 μm.

[0023] In this embodiment, the thermal conductivity of the magnesium alloy composite material is greater than or equal to 140 W / (m·K). The magnesium alloy composite material has high thermal conductivity and can be molded into various structural components with heat dissipation requirements, such as optical module housings and heat sink housings, to meet the high thermal conductivity and heat dissipation requirements of these structural components.

[0024] The second aspect of this application provides a method for preparing a magnesium alloy composite material, comprising:

[0025] Non-metallic thermally conductive particles, thermally conductive metal element powder, and magnesium alloy matrix particles are mixed to obtain a uniformly dispersed mixture; the thermally conductive metal element in the thermally conductive metal element powder can form a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles; the magnesium alloy matrix particles include the following constituent elements by mass percentage: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities;

[0026] The mixture was injection molded using a semi-solid injection molding process to obtain a magnesium alloy composite material.

[0027] The method for preparing magnesium alloy composite materials provided in this application weakens the agglomeration effect of non-metallic thermally conductive particles by introducing thermally conductive metal element powder, allowing the non-metallic thermally conductive particles to be more uniformly distributed in the magnesium alloy matrix. This enables the addition of non-metallic thermally conductive particles with a larger mass ratio to improve the thermal conductivity of the composite material. Similarly, the introduction of thermally conductive metal element powder allows for in-situ reaction at the interface between the non-metallic thermally conductive particles and the magnesium alloy matrix, generating controllable intermetallic compounds. These intermetallic compounds fill the interface, improving the interfacial bonding between the magnesium alloy matrix and the non-metallic thermally conductive particles. The magnesium alloy composite material prepared in this application, through the synergistic effect of the non-metallic thermally conductive particles, intermetallic compounds, and large semi-solid nascent magnesium grains, forms a relatively complete heat conduction pathway within the magnesium alloy composite material, achieving high thermal conductivity. The magnesium alloy composite material prepared in this application has good formability, allowing for one-time molding of thin-walled complex parts. It exhibits good interfacial bonding between the non-metallic thermally conductive particles and the matrix, combining excellent lightweight and superior thermal conductivity. Furthermore, the production process is environmentally friendly, has a short process flow, high cost-effectiveness, and can be mass-produced on a large scale.

[0028] In this embodiment of the application, the non-metallic thermally conductive particles are added at a total mass percentage of 5%-30% in the magnesium alloy composite material; the thermally conductive metal element powder is added at a total mass percentage of 0.1%-6% in the magnesium alloy composite material.

[0029] In this embodiment, the material storage temperature for injection molding is 595℃-620℃. A suitable material storage temperature is beneficial for maintaining the flow dynamics of the mixture, smoothly filling the mold, and also for the subsequent formation of intermetallic compounds and large semi-solid primary magnesium grains in the mold.

[0030] In this embodiment, the mold temperature for injection molding is 250℃-320℃. A suitable mold temperature allows the mixture to cool and solidify uniformly after entering the mold, which is beneficial for maintaining the uniform dispersion of the thermally conductive reinforcement and the formation of intermetallic compounds and large semi-solid primary magnesium grains.

[0031] In this embodiment, the screw shearing speed during injection molding is 100 rpm-200 rpm. Appropriate screw shearing speed control is beneficial for the uniform dispersion of the thermally conductive reinforcement and also for the formation of intermetallic compounds and large-particle semi-solid primary magnesium grains.

[0032] A third aspect of this application provides a powder composition for use in semi-solid molding of magnesium alloy composite materials. The powder composition comprises magnesium alloy matrix particles, non-metallic thermally conductive particles, and thermally conductive metal element powder. The thermally conductive metal element in the thermally conductive metal element powder is capable of forming a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles. The magnesium alloy matrix particles comprise the following constituent elements by mass percentage: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities.

[0033] A fourth aspect of this application provides a structural component, comprising the magnesium alloy composite material described in the first aspect or the magnesium alloy composite material prepared by the method described in the second aspect. This structural component can be various structural components with high thermal conductivity requirements, such as communication product structural components, consumer electronics product structural components, and vehicle structural components. Specifically, it can be, for example, an equipment housing, a heat sink housing, an optical module housing, etc., or it can be a reinforcing plate, a support plate, etc. The equipment housing can be, for example, a communication equipment housing, a consumer electronics product housing, a vehicle housing, etc.

[0034] This application also provides a device including the structural component described in the fourth aspect. This device may be, but is not limited to, communication equipment, electronic equipment, lighting equipment, heat dissipation equipment, etc. Using the magnesium alloy composite material from this application embodiment to manufacture the structural component in the above-mentioned device can improve the thermal conductivity of the structural component, while also providing significant weight reduction benefits, thereby enhancing product competitiveness and improving user experience in multiple ways.

[0035] This application also provides a vehicle including the structural component described in the fourth aspect. Using the magnesium alloy composite material from this application to manufacture the vehicle's structural components can improve the thermal conductivity of the components, while also offering significant weight reduction benefits, thereby enhancing product competitiveness and user experience. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application;

[0037] Figure 2 A schematic diagram of the structure of the front cover, middle frame, and back cover of a mobile phone provided in an embodiment of this application;

[0038] Figure 3 Here are metallographic microstructure images of the magnesium alloy composite material prepared in Example 1 of this application;

[0039] Figure 4 The image is a scanning electron microscope (SEM) image of the magnesium alloy composite material prepared in Example 4 of this application.

[0040] Figure 5 A photograph of a 0.5 mm thick thin-walled part formed from the magnesium alloy composite material of Example 1. Detailed Implementation

[0041] The embodiments of this application will now be described in conjunction with the accompanying drawings.

[0042] Magnesium alloys are highly favored in fields such as communications, 3C products, new energy vehicles, and aerospace due to their lightweight and high strength. However, with the continuous development of various device products, the requirements for the thermal conductivity and formability of magnesium alloys are constantly increasing. In view of this, this application provides a magnesium alloy composite material, its preparation method, and its application. This magnesium alloy composite material, by selecting an alloy matrix with a specific component ratio and introducing non-metallic thermally conductive particles and thermally conductive metal elements, achieves a combination of high thermal conductivity, good formability, and high yield strength through the synergistic effect of the components.

[0043] Near Net Shape Forming refers to a forming technology where parts, once formed, require only minimal or no further machining before being used as mechanical components.

[0044] The magnesium alloy composite material provided in this application includes magnesium alloy matrix constituent elements, non-metallic thermally conductive particles, and thermally conductive metallic elements. The non-metallic thermally conductive particles are dispersed inside the magnesium alloy composite material. The magnesium alloy matrix constituent elements, based on a total mass of 100%, include: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities.

[0045] The magnesium alloy composite material provided in this application includes alloy matrix elements in a specific ratio, as well as non-metallic thermally conductive particles and thermally conductive metallic elements introduced into the magnesium alloy composite material. Through the synergistic effect of these components, the magnesium alloy composite material possesses high thermal conductivity, good formability, and high yield strength. Specifically, the specific composition and ratio of magnesium alloy matrix elements enable the magnesium alloy matrix itself to have high thermal conductivity and a good semi-solid forming process range, allowing for the formation of an excellent semi-solid spherical crystal (primary α-Mg phase) microstructure. The magnesium alloy matrix elements include a suitable amount of Zn to form a Mg-Zn main system magnesium alloy, which is beneficial for improving the strength and hardness of the magnesium alloy, enhancing corrosion resistance, improving processing and forming performance, and reducing the tendency for hot cracking. A suitable amount of Al can further lower the liquidus temperature and improve the semi-solid formability. Suitable amounts of La (lanthanum) and Ce (cerium) can form Al with Al. 11 La3, Al 11 The Ce3 phase reduces the solid solution effect of Al in Mg, decreases lattice distortion, and improves the thermal conductivity and mechanical properties of magnesium alloys. Simultaneously, the high magnesium content helps maintain the lightweight and good corrosion resistance of magnesium alloy composites. Furthermore, the introduction of non-metallic thermally conductive particles and thermally conductive metallic elements into the interior of magnesium alloy composites can effectively enhance their thermal conductivity.

[0046] In this embodiment of the application, the magnesium alloy matrix comprises 87.5%-95% Mg (magnesium) by mass, meaning that the mass percentage of Mg in the magnesium alloy matrix is ​​87.5%-95%. A higher Mg (magnesium) content is beneficial for leveraging the advantages of magnesium alloys, improving the strength of magnesium alloy composites, reducing weight, and reducing brittleness. For example, the mass percentage of Mg in the magnesium alloy matrix can be 87.5%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95%.

[0047] In this embodiment, the magnesium alloy matrix comprises 4%-10% Zn (zinc) by mass, meaning that the mass percentage of Zn in the magnesium alloy matrix is ​​4%-10%. The addition of a suitable amount of Zn not only ensures that the liquidus temperature of the magnesium alloy is below 625°C, but also prevents the solidification range from becoming too wide, thus making it well-suited for semi-solid injection molding processes and reducing the tendency for hot cracking. For example, the mass percentage of Zn in the magnesium alloy matrix can be 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0048] In this embodiment, the magnesium alloy matrix comprises 0.05%-1% Al (aluminum) by mass, meaning that the mass percentage of Al in the magnesium alloy matrix is ​​0.05%-1%. The addition of a suitable amount of Al can further reduce the liquidus temperature of the magnesium alloy, improve its semi-solid forming performance, and thus better suit the semi-solid injection molding process to achieve near-net-shape forming of complex structural parts; at the same time, it does not significantly negatively impact the thermal conductivity of the magnesium alloy. For example, the mass percentage of Al in the magnesium alloy matrix can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%. To better balance thermal conductivity, formability, and mechanical properties, in some embodiments, the mass percentage of Al in the magnesium alloy matrix is ​​0.05%-0.8%; to further improve thermal conductivity and formability, in some embodiments, the mass percentage of Al in the magnesium alloy matrix is ​​0.05%-0.5%.

[0049] In this application, the magnesium alloy matrix includes Al, which is beneficial for improving semi-solid forming performance. However, Al exhibits a solid solution effect with Mg, and the formation of the solid solution leads to lattice distortion of Mg. This lattice distortion affects the mechanical and thermal conductivity of the magnesium alloy. Specifically, lattice distortion hinders dislocation movement, thus affecting the plastic deformation process of the magnesium alloy; Al atoms shorten the mean free path of electrons and phonons by substituting Mg atoms, thereby adversely affecting thermal conductivity. To reduce the lattice distortion caused by the introduction of Al, the magnesium alloy matrix in this application also includes La (lanthanum) and / or Ce (cerium).

[0050] In this embodiment, the magnesium alloy matrix comprises La (lanthanum) and Ce (cerium) in a total mass ratio of 0.05%-2%, meaning the total mass ratio of La (lanthanum) and Ce (cerium) in the magnesium alloy matrix is ​​0.05%-2%. The magnesium alloy matrix may include La (lanthanum) but exclude Ce (cerium), meaning the mass percentage of La (lanthanum) is 0.05%-2% and the mass percentage of Ce (cerium) is 0; or it may include Ce (cerium) but exclude La (lanthanum), meaning the mass percentage of Ce (cerium) is 0.05%-2% and the mass percentage of La (lanthanum) is 0; or it may include both La (lanthanum) and Ce (cerium), where the mass percentages of both La (lanthanum) and Ce (cerium) are greater than 0, and the sum of the mass percentages of La (lanthanum) and Ce (cerium) in the magnesium alloy matrix is ​​0.05%-2%. Suitable amounts of La (lanthanum) and Ce (cerium) can react with Al to form Al...11 La3, Al 11 The Ce3 phase reduces the solid solution effect of Al in Mg, reduces lattice distortion, and improves the thermal conductivity and mechanical properties of magnesium alloys; it also enables Al to... 11 La3, Al 11 The content of the second phase Ce3 phase is kept within a suitable range to avoid Al 11 La3, Al 11 Excessive Ce3 phase leads to high melt viscosity during molding, resulting in reduced semi-solid formability. For example, the combined mass percentages of La (lanthanum) and Ce (cerium) in the magnesium alloy matrix are 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, and 2%.

[0051] In this embodiment of the application, the mass ratio of La (lanthanum) in the magnesium alloy matrix can be 0-2%; exemplary values ​​include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, and 2%.

[0052] In this embodiment of the application, the mass ratio of Ce (cerium) in the magnesium alloy matrix can be 0-2%; exemplary values ​​can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%.

[0053] In this embodiment of the application, in order to better balance the semi-solid forming performance and thermal conductivity of the magnesium alloy composite material, the ratio of the mass percentage of Al to the sum of the mass percentages of La and Ce in the magnesium alloy matrix can be controlled within the range of 1:(1-15). For example, the ratio of the mass percentage of Al to the sum of the mass percentages of La and Ce can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15.

[0054] In this embodiment of the application, to further improve the performance of the magnesium alloy composite material, the magnesium alloy matrix may also include other constituent elements, such as one or more of Y (yttrium), Mn (manganese), Sn (tin), Gd (gadolinium), Ca (calcium), and Zr (zirconium). The total mass percentage of the other constituent elements in the magnesium alloy matrix may be less than or equal to 1%. For example, the mass percentage of Mn (manganese) may be 0.01%-0.2%.

[0055] In some embodiments of this application, other constituent elements include Y (yttrium), and the magnesium alloy matrix comprises 0.01%-0.5% Y (yttrium) by mass. The inclusion of a suitable amount of yttrium in the magnesium alloy matrix is ​​beneficial for better reducing the solid solution effect of Al in Mg, reducing lattice distortion, and simultaneously improving the corrosion resistance of the magnesium alloy composite material. Exemplarily, the magnesium alloy matrix comprises 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5% Y (yttrium) by mass.

[0056] In this embodiment of the application, the constituent elements of the magnesium alloy matrix also include unavoidable impurities with a mass ratio of ≤0.2%, and unavoidable impurities may include, but are not limited to, iron (Fe) and silicon (Si).

[0057] In this embodiment of the application, the total mass percentage of the magnesium alloy matrix constituent elements in the magnesium alloy composite material can be 68%-95%. For example, it can be 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, or 95%. In some embodiments, the total mass percentage of the magnesium alloy matrix constituent elements in the magnesium alloy composite material can be 80%-95%. In some embodiments, the total mass percentage of the magnesium alloy matrix constituent elements in the magnesium alloy composite material can be 80%-92%.

[0058] To improve the thermal conductivity of magnesium alloy composite materials, the magnesium alloy composite material in this application embodiment further includes non-metallic thermally conductive particles, which are dispersed within the magnesium alloy composite material. The magnesium alloy matrix constituent elements are used to form the magnesium alloy matrix, and the non-metallic thermally conductive particles are uniformly dispersed within the magnesium alloy matrix. The dispersion of non-metallic thermally conductive particles within the magnesium alloy matrix helps to construct internal heat conduction pathways in the magnesium alloy composite material, thereby improving the thermal conductivity of the composite material.

[0059] Non-metallic thermally conductive particles can be non-metallic materials with a thermal conductivity greater than 300 W / (m·K). Selecting non-metallic thermally conductive particles with a high thermal conductivity is beneficial for achieving a significant improvement in thermal conductivity with a relatively small addition amount. In this application embodiment, the non-metallic thermally conductive particles can be aluminum nitride particles, carbon-based thermally conductive particles, etc., and the carbon-based thermally conductive particles can be one or more of graphite particles, diamond particles, and graphene particles. In this application embodiment, it may include, but is not limited to, one or more of aluminum nitride particles, graphite particles, diamond particles, and graphene particles. The above-mentioned non-metallic thermally conductive particles have high thermal conductivity and high strength, which is beneficial for improving the thermal conductivity and strength of magnesium alloy composite materials. The above-mentioned non-metallic thermally conductive particles can be spherical or nearly spherical in shape, which is beneficial for dispersion in the magnesium alloy system. Graphite particles can also act as a lubricant during the molding process, improving molding performance and enabling magnesium alloy composite materials to better utilize semi-solid molding processes to achieve near-net-shape forming of complex thin-walled parts.

[0060] In this embodiment, the particle size of the non-metallic thermally conductive particles can be 1μm-150μm. Controlling the particle size of the non-metallic thermally conductive particles within a suitable range is beneficial for their uniform dispersion within the magnesium alloy composite material, and also helps to better improve the strength and hardness of the magnesium alloy composite material. In some embodiments, the particle size of the non-metallic thermally conductive particles can be 1μm, 2μm, 5μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 110μm, 120μm, 130μm, 140μm, or 150μm. In order to achieve better uniform dispersion and improve the thermal conductivity and molding properties of magnesium alloy composites, in some embodiments, the particle size of non-metallic thermally conductive particles can be in the range of 10μm-150μm.

[0061] In this embodiment, the mass percentage of non-metallic thermally conductive particles in the magnesium alloy composite material can be 5%-30%. Theoretically, the higher the mass of non-metallic thermally conductive particles added to the magnesium alloy, the better it is for improving the thermal conductivity of the magnesium alloy composite material. However, the addition of too many non-metallic thermally conductive particles can exacerbate agglomeration and entanglement, limiting the improvement of the composite material's thermal conductivity. On the other hand, it may lead to increased brittleness of the composite material, resulting in defects such as cracks during processing and reducing the fracture reliability of the magnesium alloy composite material structure. This embodiment controls the total mass percentage of non-metallic thermally conductive particles within a suitable range, which is beneficial for the uniform dispersion of non-metallic thermally conductive particles in the magnesium alloy matrix, avoiding agglomeration and entanglement, maximizing the role of non-metallic thermally conductive particles in improving the thermal conductivity and strength of the magnesium alloy composite material, and also better controlling the brittleness of the magnesium alloy composite material at a lower level, thereby improving the reliability of the structural parts obtained by molding the magnesium alloy composite material. In some embodiments, the mass percentage of non-metallic thermally conductive particles in the magnesium alloy composite material can be 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%.

[0062] In this embodiment, thermal conductivity can be further improved by introducing thermally conductive metal elements into the magnesium alloy composite material. The thermally conductive metal element can be one or more metal elements whose introduction, whether alone or together, results in a magnesium lattice volume change of less than 5% and has a higher thermal conductivity than magnesium. Using elements that minimize the volume change (i.e., lattice distortion) of the magnesium lattice is beneficial in reducing the negative impacts such as decreased thermal conductivity caused by lattice distortion. Understandably, the smaller the volume change of the magnesium lattice after introduction into the magnesium alloy composite material, the better it is to avoid negative impacts. For example, the thermally conductive metal element can be one or more metal elements whose introduction, whether alone or together, results in a magnesium lattice volume change of less than 5%, less than 4%, less than 3%, less than 2%, or less than 1%.

[0063] In some embodiments of this application, the thermally conductive metal element includes a metal element capable of forming a first intermetallic compound with the constituent elements of the magnesium alloy matrix. In some embodiments of this application, the thermally conductive metal element may be one or more of nickel, copper, aluminum, silver, and zinc. Nickel, copper, aluminum, silver, and zinc can all reduce the lattice distortion of magnesium crystals; their individual or combined introduction can minimize the distortion of the magnesium lattice and can form corresponding first intermetallic compounds with the constituent elements of the magnesium alloy matrix, thereby improving thermal conductivity, improving the interfacial bonding between the magnesium alloy matrix and non-metallic thermally conductive particles in the magnesium alloy composite material, and improving the performance of the composite material. In some embodiments of this application, the thermally conductive metal element includes copper. In some embodiments of this application, the thermally conductive metal element includes copper, and one or more of nickel, aluminum, silver, and zinc. In some embodiments of this application, the thermally conductive metal element includes nickel. In some embodiments of this application, the thermally conductive metal element includes nickel, and one or more of copper, aluminum, silver, and zinc. In some embodiments of this application, the thermally conductive metal element includes silver. In some embodiments of this application, the thermally conductive metal element includes silver, and one or more of nickel, copper, aluminum, and zinc. In some embodiments of this application, the thermally conductive metal element may be one or more selected from nickel, copper, and silver. In some embodiments of this application, the thermally conductive metal element may be one or more selected from nickel, copper, and silver, and one or more selected from aluminum and zinc. In magnesium alloy composite materials, the thermally conductive metal element can form a corresponding first intermetallic compound with the constituent elements of the magnesium alloy matrix. For example, copper can form a copper-magnesium intermetallic compound with magnesium in the magnesium alloy matrix, copper can form a copper-zinc intermetallic compound with zinc in the magnesium alloy matrix, and silver can form a silver-magnesium intermetallic compound with magnesium in the magnesium alloy matrix.

[0064] Given that the magnesium alloy matrix has a good process window, the use of non-metallic thermally conductive particles and thermally conductive metal powders can further enhance the forming ability of the magnesium alloy, exert a lubricating effect, and have excellent casting fluidity. Complex structures can be directly semi-solid molded in one step at a lower temperature, avoiding the problem of complex preparation process of traditional high thermal conductivity magnesium-based composite materials. Precision structural parts can be obtained without secondary hot deformation processing.

[0065] In this embodiment, within the magnesium alloy composite material, at least some, or even all, of the thermally conductive metal elements form a first intermetallic compound with the constituent elements of the magnesium alloy matrix. The first intermetallic compound is dispersed throughout the magnesium alloy composite material, potentially forming a network structure that facilitates thermal conductivity. The internal structure of the magnesium alloy composite material includes a magnesium alloy matrix, with at least a portion of the first intermetallic compound distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles. In some embodiments, a majority (greater than 50% by mass) or all of the first intermetallic compound is distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles. The first intermetallic compound distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles improves the interfacial bonding between the magnesium alloy matrix and the non-metallic thermally conductive particles, which were originally neither reactive nor wettable. The first intermetallic compound is relatively concentrated at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles. This is mainly because, in the preparation process of the magnesium alloy composite material in this application embodiment, the constituent elements of the magnesium alloy matrix are introduced in the form of magnesium alloy matrix particles, and the thermally conductive metal elements are introduced in the form of thermally conductive metal element powder. In this way, the thermally conductive metal element powder can not only act as a dispersant for the non-metallic thermally conductive particles in the magnesium alloy matrix, improving the problem of poor wettability between the magnesium alloy matrix and the non-metallic thermally conductive particles, and improving the dispersion uniformity of the non-metallic thermally conductive particles in the magnesium alloy composite material; it can also react with the magnesium alloy matrix in situ to generate the first intermetallic compound. These first intermetallic compounds can partially fill the interfacial gaps between the magnesium alloy matrix and the non-metallic thermally conductive particles, improving the wettability between the magnesium alloy matrix and the non-metallic thermally conductive particles, avoiding the formation of micropores, and improving the interfacial bonding between the non-metallic thermally conductive particles and the magnesium alloy matrix.

[0066] In this embodiment, the mass percentage of thermally conductive metal elements in the magnesium alloy composite material is 0.1%-6%. The introduction of an appropriate amount of thermally conductive metal elements can promote the uniform dispersion of non-metallic thermally conductive particles in the magnesium alloy matrix during the preparation of the magnesium alloy composite material. It can also react in situ with the magnesium alloy matrix to generate an appropriate amount of first intermetallic compound, improving the interfacial bonding between the non-metallic thermally conductive particles and the magnesium alloy matrix. This allows for the addition of more non-metallic thermally conductive particles to the magnesium alloy composite material and achieves uniform dispersion, thereby improving the thermal conductivity of the magnesium alloy composite material. Furthermore, it avoids the negative impacts of excessive thermally conductive metal elements on the magnesium alloy composite material, such as increased weight and weakened mechanical properties. In some embodiments, the total mass percentage of thermally conductive metal elements in the magnesium alloy composite material is 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 5%, 5.5%, and 6%.

[0067] In this application, the mass ratio of non-metallic thermally conductive particles to thermally conductive metal elements can be (2-12):1. A suitable mass ratio is beneficial for better utilizing the synergistic effect of non-metallic thermally conductive particles and thermally conductive metal elements to improve the thermal conductivity of magnesium alloy composite materials and to achieve uniform dispersion of non-metallic thermally conductive particles within the magnesium alloy composite material. For example, the mass ratio of non-metallic thermally conductive particles to thermally conductive metal elements can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, or 12:1. To better improve the performance of magnesium alloy composite materials while balancing high thermal conductivity and better formability, in some embodiments of this application, the mass ratio of non-metallic thermally conductive particles to thermally conductive metal elements can be (2-10):1.

[0068] In some embodiments of this application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 5%-32%. To better balance the mechanical properties, thermal conductivity, and processing performance of the magnesium alloy composite material, in some embodiments of this application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 5%-20%. For example, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%. To further balance the mechanical properties, thermal conductivity, and processing performance, in some embodiments of this application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 8%-20%. In some embodiments of this application, the mass percentage of the magnesium alloy matrix constituent elements in the magnesium alloy composite material is 80%-92%. For example, the mass percentage of the constituent elements of the magnesium alloy matrix is ​​80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, and 92%.

[0069] To better improve the performance of magnesium alloy composite materials, balancing high thermal conductivity and better formability, in some embodiments of this application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 5%-20%, the mass percentage of magnesium alloy matrix constituent elements is 80%-95%, and the sum of the mass percentages of non-metallic thermally conductive particles, thermally conductive metal elements, and magnesium alloy matrix constituent elements is 100%. In some embodiments of this application, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements in the magnesium alloy composite material is 8%-20%, the mass percentage of magnesium alloy matrix constituent elements is 80%-92%, and the sum of the mass percentages of non-metallic thermally conductive particles, thermally conductive metal elements, and magnesium alloy matrix constituent elements is 100%.

[0070] In this embodiment of the application, the internal microstructure of the magnesium alloy composite material includes a magnesium alloy matrix, which includes an α-Mg phase, and the α-Mg phase includes a secondary α-Mg phase and a primary α-Mg phase dispersed in the secondary α-Mg phase.

[0071] The primary α-Mg phase refers to the magnesium matrix phase that first precipitates from the liquid phase during the solidification process of magnesium alloys. The primary α-Mg phase can be a spherical or near-spherical semi-solid primary crystalline phase. In the embodiments of this application, the particle size of the primary α-Mg phase is 10μm-100μm. These large-particle primary α-Mg phases, under the synergistic effect of non-metallic thermally conductive particles and the first intermetallic compound, jointly construct a heat conduction pathway, thereby resulting in high strengthening efficiency of the non-metallic thermally conductive particle-reinforced phase and better enabling the magnesium alloy composite material to possess both excellent lightweight and ultra-high thermal conductivity. For example, the particle size of the primary α-Mg phase can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm.

[0072] In this embodiment, the area percentage of the primary α-Mg phase in any cross-section of the magnesium alloy composite material is 5%-50%. The presence of a suitable amount of primary α-Mg phase is beneficial for improving the thermal conductivity of the magnesium alloy material, while also maintaining good mechanical properties and other excellent properties. For example, the area percentage of the primary α-Mg phase in any cross-section of the magnesium alloy composite material can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0073] The secondary α-Mg phase is a magnesium matrix phase that precipitates subsequently during the growth process after the formation of the primary α-Mg phase. In the embodiments of this application, the particle size of the secondary α-Mg phase is greater than or equal to 1 μm and less than 10 μm. Exemplarily, the particle size of the secondary α-Mg phase can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0074] In this embodiment of the application, the magnesium alloy matrix may further include a second intermetallic compound formed from the constituent elements of the magnesium alloy matrix.

[0075] In this embodiment, the thermal conductivity of the magnesium alloy composite material is greater than or equal to 140 W / (m·K). The high thermal conductivity of the magnesium alloy composite material allows it to be molded into various structural components with heat dissipation requirements, such as optical module housings and heat sink housings, to meet the high heat dissipation demands of these components. In some embodiments, the thermal conductivity of the magnesium alloy composite material is greater than or equal to 150 W / (m·K). In some embodiments, the thermal conductivity of the magnesium alloy composite material is greater than or equal to 155 W / (m·K). In some embodiments, the thermal conductivity of the magnesium alloy composite material is greater than or equal to 160 W / (m·K).

[0076] In this embodiment, the yield strength of the magnesium alloy composite material is greater than or equal to 100 MPa. Yield strength is the yield limit of a metallic material when it undergoes yielding, that is, the stress that resists slight plastic deformation. Magnesium alloy composite materials have high yield strength, which can better resist external pressure, reduce the risk of deformation and fracture, improve service reliability, and also facilitate lightweight structural design. In some embodiments, the yield strength of the magnesium alloy composite material is greater than or equal to 110 MPa. In some embodiments, the yield strength of the magnesium alloy composite material is greater than or equal to 120 MPa. In some embodiments, the yield strength of the magnesium alloy composite material is greater than or equal to 130 MPa. In some embodiments, the yield strength of the magnesium alloy composite material is greater than or equal to 140 MPa.

[0077] The magnesium alloy composite material provided in this application has the advantages of being lightweight, having high thermal conductivity, good formability, and high strength. It can be used to manufacture complex structural parts in one step, making it highly practical. It can be used to form parts for various devices, such as electronic device housings, to improve product quality and market competitiveness, and enhance user experience.

[0078] This application also provides a method for preparing a magnesium alloy composite material, comprising:

[0079] S101. Non-metallic thermally conductive particles, thermally conductive metal element powder, and magnesium alloy matrix particles are mixed to obtain a uniformly dispersed mixture; the thermally conductive metal element in the thermally conductive metal element powder can form a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles; the magnesium alloy matrix particles include the following mass percentages of magnesium alloy matrix constituent elements: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities;

[0080] S102. The mixture is injection molded using a semi-solid injection molding process to obtain a magnesium alloy composite material.

[0081] In step S101, the magnesium alloy matrix particles can be prepared as follows: raw materials are prepared according to the constituent elements of the magnesium alloy matrix, and magnesium alloy matrix particles are obtained through melting, casting, and pelletizing. The constituent elements of the magnesium alloy matrix are as described above and will not be repeated here. The raw materials can be elemental or alloys of the constituent elements. For example, the raw material for Mg can be pure magnesium, the raw material for Zn can be pure zinc, the raw material for Al can be pure aluminum, and the raw materials for La and Ce can be Mg-La master alloys and Mg-Ce master alloys. The magnesium alloy matrix particles can be controlled at a millimeter-scale particle size; for example, the particle size of the magnesium alloy matrix particles can be 0.3mm-3mm. Controlling the magnesium alloy matrix particles to a suitable particle size facilitates their dispersion during the mixing process and also helps reduce machining costs. In some embodiments, the particle size of the magnesium alloy matrix particles can be 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, or 3 mm. The melting and casting temperature can be 700℃-720℃.

[0082] In step S101, the non-metallic thermally conductive particles can be added at a total mass ratio of 5%-30% in the magnesium alloy composite material. This facilitates the uniform dispersion of the non-metallic thermally conductive particles in the magnesium alloy matrix, avoiding agglomeration and entanglement, maximizing the role of the non-metallic thermally conductive particles in improving the thermal conductivity and strength of the magnesium alloy composite material, and also better controlling the brittleness of the magnesium alloy composite material at a lower level, thereby improving the reliability of the structural parts obtained by molding the magnesium alloy composite material. The specific types, mass ratios, and particle sizes of the non-metallic thermally conductive particles have been described above and will not be repeated here.

[0083] In this application, the thermally conductive metal element powder refers to the powder of the aforementioned thermally conductive metal element, and the selection of the thermally conductive metal element is as described above. In some embodiments of this application, the thermally conductive metal element may be one or more of nickel, copper, aluminum, silver, and zinc. The thermally conductive metal element powder may be a pure metal powder (i.e., elemental powder) containing one thermally conductive metal element, or it may be an alloy powder containing two or more thermally conductive metal elements. That is, the thermally conductive metal element powder may be a pure metal powder or alloy powder containing one or more of nickel, copper, aluminum, silver, and zinc. In some embodiments, the thermally conductive metal element powder includes one or more of nickel powder, copper powder, aluminum powder, silver powder, and zinc powder. In some embodiments, the thermally conductive metal element powder includes copper-nickel alloy powder, copper-zinc alloy powder, copper-silver alloy powder, copper-aluminum alloy powder, etc. The thermally conductive metal element powder may be added one or more as needed. When adding the thermally conductive metal element powder requires the simultaneous introduction of two or more thermally conductive metal elements, it may be by simultaneously adding two or more pure metal powders containing one thermally conductive metal element, or by adding alloy powder containing two or more thermally conductive metal elements.

[0084] In this embodiment of the application, the thermally conductive metal element powder can be added at a total mass percentage of 0.1%-6% in the magnesium alloy composite material. For example, the thermally conductive metal element powder can be added at a total mass percentage of 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 5%, 5.5%, and 6% in the magnesium alloy composite material.

[0085] In this embodiment, the diameter of the thermally conductive metal element powder can be 0.1 μm-20 μm. A smaller, suitable particle size of the thermally conductive metal element powder is beneficial for its uniform dispersion and for its distribution on the surface of more non-metallic thermally conductive particles, thus improving the dispersion of the non-metallic thermally conductive particles. In some embodiments, the diameter of the thermally conductive metal element powder is 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0086] In some embodiments, to achieve better dispersion, the particle size of the non-metallic thermally conductive particles is controlled to be greater than or equal to three times the diameter of the thermally conductive metal element powder.

[0087] The added thermally conductive metal element powder can utilize the strong van der Waals forces of the non-metallic thermally conductive particles for physical adsorption during the mixing process. It adsorbs onto the surface of the non-metallic thermally conductive particles and at the interface between the non-metallic thermally conductive particles and the magnesium alloy matrix particles. This results in two advantages: firstly, the strong van der Waals forces in the non-metallic thermally conductive particles, which easily lead to agglomeration and entanglement, are weakened by the adsorption of the thermally conductive metal element powder, promoting uniform dispersion of the non-metallic thermally conductive particles. Therefore, a larger mass ratio of non-metallic thermally conductive particles can be added and uniformly dispersed. Secondly, the thermally conductive metal element powder can react in situ with the magnesium alloy matrix during the forming process in step S102 to generate a first intermetallic compound. This first intermetallic compound can partially fill the interfacial gaps between the magnesium alloy matrix and the non-metallic thermally conductive particles, improving the wettability of the magnesium alloy matrix and the non-metallic thermally conductive particles, preventing the formation of micropores, and improving the interfacial bonding between the non-metallic thermally conductive particles and the magnesium alloy matrix.

[0088] In this embodiment, the non-metallic thermally conductive particles, thermally conductive metal element powder and magnesium alloy matrix particles can be mixed in one step, i.e., mixed simultaneously; or they can be mixed in multiple steps.

[0089] In some embodiments of this application, in order to better utilize the thermally conductive metal element powder to improve the uniform dispersion of the non-metallic thermally conductive particles, the operation of mixing the non-metallic thermally conductive particles, the thermally conductive metal element powder, and the magnesium alloy matrix particles specifically includes:

[0090] The non-metallic thermally conductive particles and thermally conductive metal element powder are pre-mixed and then mixed with magnesium alloy matrix particles, which is a two-step mixing process.

[0091] In this way, during the premixing stage, the thermally conductive metal element powder is pre-physically adsorbed onto the surface of the non-metallic thermally conductive particles by the strong van der Waals forces of the non-metallic thermally conductive particles, which can reduce the agglomeration tendency of the non-metallic thermally conductive particles and improve the dispersibility of both.

[0092] Non-metallic thermally conductive particles and thermally conductive metal element powders can be dried before mixing.

[0093] In this embodiment, the mixing of non-metallic thermally conductive particles, thermally conductive metal element powder, and magnesium alloy matrix particles can be carried out in a mixer, which can be a three-dimensional mixer, a vertical mixer, or other mixing equipment. During the mixing process, the speed of the mixer can be 20 rpm to 100 rpm, for example, 20 rpm, 30 rpm, 50 rpm, 80 rpm, or 100 rpm. If mixing is done in one step, the mixing time is 14 min to 70 min. If mixing is done in two steps, the first step can take 4 min to 20 min, and the second step can take 10 min to 50 min.

[0094] In step S102, the semi-solid injection molding process can be achieved using an injection molding machine to inject the mixture into magnesium alloy composite material structural parts of the required shape and size. The injection molding machine may include an injection system, a heating system, and a mold. The injection system includes a barrel, an injection device connected to the barrel, and a screw that cooperates with the barrel. The barrel stores the mixture, the screw conveys the mixture to the injection device, and the injection device injects the mixture into the mold. The heating system heats the mixture. Specifically, the injection molding machine may be a semi-solid metal thixotropic injection molding machine.

[0095] The specific process of using semi-solid injection molding to injection mold the mixture to obtain magnesium alloy composite materials can be as follows:

[0096] The mixture is transferred to the barrel of an injection molding machine, where a rotating screw shears and propels the material, gradually heating it and injecting it to obtain a magnesium alloy composite material.

[0097] In this embodiment, the injection molding slurry temperature can be 595℃-630℃. Slurry temperature refers to the temperature at which the mixture is heated into a semi-solid slurry while stored in the barrel. A suitable slurry temperature is beneficial for maintaining the flowability of the mixture, facilitating smooth filling of the mold, and also for the subsequent formation of intermetallic compounds and large semi-solid primary magnesium grains injected into the mold. In some embodiments, the injection molding slurry temperature can be 595℃, 600℃, 605℃, 610℃, 615℃, 620℃, 625℃, or 630℃. The injection speed can be 2m / s-4m / s, for example, 2m / s, 3m / s, or 4m / s.

[0098] In this embodiment, the mold temperature for injection molding can be 250℃-320℃. Mold temperature refers to the temperature inside the mold. A suitable mold temperature allows the mixture to cool and solidify uniformly after entering the mold, which is beneficial for maintaining the uniform dispersion of non-metallic thermally conductive particles and the formation of intermetallic compounds and large semi-solid primary magnesium grains. In some embodiments, the mold temperature for injection molding can be 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, or 320℃.

[0099] In this embodiment, the screw shearing speed during injection molding can be 100 rpm to 200 rpm. Screw shearing speed refers to the shear rate experienced by the barrel per second during the mixing process. The specific calculation formula is as follows: Screw shearing speed = (Screw rotation speed × π × Screw diameter) / Barrel diameter. Appropriate screw shearing speed control is beneficial for the uniform dispersion of non-metallic thermally conductive particles and also for the formation of intermetallic compounds and large semi-solid primary magnesium grains. For example, the screw shearing speed during injection molding can be 100 rpm, 120 rpm, 150 rpm, 180 rpm, or 200 rpm.

[0100] After molding is completed, the part can be cooled for 4-10 seconds before the mold is opened and the part is removed.

[0101] Semi-solid injection molding is a continuous preparation process involving simultaneous mixing, melting, and solidification. This process is beneficial for obtaining magnesium alloy composites with uniformly dispersed non-metallic thermally conductive particles. It also facilitates the in-situ reaction of thermally conductive metal element powder with the magnesium alloy matrix during molding to form intermetallic compounds, and promotes the formation of large-particle semi-solid primary magnesium grains during the formation of the magnesium alloy matrix. After semi-solid injection molding, the magnesium alloy composite material forms a specific composite structure containing a primary α-Mg phase, non-metallic thermally conductive particles, a network-like second phase (first intermetallic compound), and a post-solidified liquid phase (secondary α-Mg phase). This specific structure exhibits significantly superior electronic thermal conductivity pathways compared to traditional magnesium alloys, resulting in a substantial improvement in thermal conductivity.

[0102] The method for preparing magnesium alloy composite materials provided in this application weakens the agglomeration effect of non-metallic thermally conductive particles by introducing thermally conductive metal element powder, allowing the non-metallic thermally conductive particles to be more uniformly distributed in the magnesium alloy matrix. This enables the addition of non-metallic thermally conductive particles with a larger mass ratio to improve the thermal conductivity of the composite material. Similarly, the introduction of thermally conductive metal element powder allows for in-situ reaction at the interface between the non-metallic thermally conductive particles and the magnesium alloy matrix, which originally neither react nor wet each other, to generate a controllable first intermetallic compound. This first intermetallic compound can fill the interface, improving the interaction between the magnesium alloy matrix and the non-metallic matrix. The interface bonding of the thermally conductive particles; the magnesium alloy composite material prepared in this application forms a relatively complete heat conduction path inside the magnesium alloy composite material through the synergistic effect of non-metallic thermally conductive particles, the first intermetallic compound, and large semi-solid nascent magnesium grains, which can achieve high thermal conductivity; the magnesium alloy composite material prepared in this application has good molding properties and can be molded into thin-walled complex parts in one step. The interface bonding between the non-metallic thermally conductive particles and the matrix is ​​good, and it has both excellent lightweight and excellent thermal conductivity. Moreover, the production process is environmentally friendly, has a short process, high cost performance, and can be mass-produced on a large scale.

[0103] This application also provides a powder composition for semi-solid molding of magnesium alloy composite materials. The powder composition comprises magnesium alloy matrix particles, non-metallic thermally conductive particles, and thermally conductive metal element powder. The thermally conductive metal element in the thermally conductive metal element powder is capable of forming a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles. The magnesium alloy matrix particles comprise the following magnesium alloy matrix constituent elements by mass percentage: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities. The specific descriptions of the magnesium alloy matrix particles, non-metallic thermally conductive particles, and thermally conductive metal element powder are as described above and will not be repeated here.

[0104] This application also provides a structural component, which includes the magnesium alloy composite material described in the embodiments of this application or the magnesium alloy composite material prepared by the preparation method described in the embodiments of this application. The structural component may be made wholly or partially using the aforementioned magnesium alloy composite material. The structural component can be various structural components with high thermal conductivity requirements, such as communication product structural components, consumer electronics product structural components, and vehicle structural components. Specifically, it can be, for example, an equipment housing, a heat sink housing, an optical module housing, etc., or it can be a reinforcing plate, a support plate, etc. The equipment housing can be, for example, a communication equipment housing, a consumer electronics product housing, a vehicle housing, etc.

[0105] This application also provides a device that includes the aforementioned structural components, specifically structural components made from the aforementioned magnesium alloy composite material. This device may be, but is not limited to, communication equipment, electronic equipment, lighting equipment, heat dissipation equipment, etc.

[0106] See Figure 1 This application provides an electronic device 100, which includes a housing 101 and components such as a motherboard and battery located inside the housing 101 (not shown in the figure). The housing 101 is entirely or partially made of the magnesium alloy composite material described above in this application. The electronic device 100 may include mobile phones, tablets, laptops, wearable devices, portable computers, super mobile personal computers (MPCs), handheld computers, walkie-talkies, netbooks, POS machines, personal digital assistants (PDAs), dashcams, virtual reality devices, smart projectors, communication optical modules, satellite modules, wireless USB flash drives, Bluetooth speakers / headphones, or pre-installed automotive devices, etc., mobile terminals or fixed terminals with frames or housings.

[0107] Taking mobile phones as an example of electronic devices, Figure 2 This is a structural diagram of the front cover, middle frame, and back cover of a mobile phone provided in an embodiment of this application. Figure 2 As shown, the mobile phone casing 101 may specifically include a front cover 111 assembled on the front side of the phone (i.e., the side of the display screen), and may also include a back cover 113 assembled on the rear side. In some embodiments, the casing 101 may also include a middle frame 112 located between the front cover 111 and the back cover 113, the middle frame 112 being used to support components such as the motherboard and battery. In the embodiments of this application, the front cover 111, the back cover 113, and / or the middle frame 112 are integrally formed by the magnesium alloy composite material casing provided in the embodiments of this application, or a portion of the front cover 111, the back cover 113, and / or the middle frame 112 are formed by the magnesium alloy composite material casing provided in the embodiments of this application, for example, a portion of the back cover 113 or a portion of the front cover 111 and the middle frame 112 are formed by the magnesium alloy composite material casing provided in the embodiments of this application. In some embodiments of this application, the back cover 113 and the middle frame 112 may be an integral structure; in other embodiments of this application, the back cover 113 and the middle frame 112 may be separate structures. The mobile phone also includes a display screen. In full-screen phones, the housing 101 generally does not include a front cover; the mid-frame is located between the display and the back cover. Alternatively, in some full-screen phones, the housing 101 may not include a mid-frame that is exposed to the outside.

[0108] The magnesium alloy composite material used in the embodiments of this application is used to prepare electronic device housings, which can improve the thermal conductivity of electronic devices and also has good weight reduction benefits, thereby enhancing product competitiveness and improving user experience in many ways.

[0109] This application also provides a vehicle that includes the aforementioned structural components, specifically structural components made from the aforementioned magnesium alloy composite material. Using the magnesium alloy composite material of this application to manufacture vehicle structural components can improve the thermal conductivity of the structural components, while also providing significant weight reduction benefits, thereby enhancing product competitiveness and user experience.

[0110] The embodiments of this application will be further described below through multiple examples.

[0111] Example 1

[0112] A method for preparing a magnesium alloy composite material, comprising:

[0113] S1. Prepare raw materials according to the following composition of magnesium alloy matrix elements: Zn mass content is 8.5wt.%, Al mass content is 0.2wt.%, La and Ce total mass content is 0.5wt.%, other impurity element mass content is ≤0.1wt.%, and the remainder is Mg; melt the raw materials, cast them at 720℃, and then granulate them to obtain magnesium alloy matrix particles with a particle size of 0.3mm-3mm;

[0114] S2. Take carbon-based thermally conductive particles with a diameter of 20μm-120μm and dry them in an oven at 200℃ for 30min. Then, premix them with thermally conductive metal powder with a diameter of 0.2μm-20μm in a mixer for 15min. Next, add the magnesium alloy matrix particles obtained in step S1 to the mixer and mix for 15min to obtain a uniformly dispersed mixture. The thermally conductive metal powder includes zinc powder, aluminum powder, and copper powder. The mass ratio of the magnesium alloy matrix particles is 85wt%, the sum of the mass ratios of the carbon-based thermally conductive particles and the thermally conductive metal powder is 15%, and the mass ratio of the carbon-based thermally conductive particles to the thermally conductive metal powder is 4:1.

[0115] S3. Add the mixture obtained in step S2 to a semi-solid injection molding machine, store the material at a heating temperature of 625℃, set the screw shearing speed to 120rpm, and then quickly inject the semi-solid mixture into the mold for molding. The cooling time is 6s. Open the mold to obtain a one-time molded high thermal conductivity magnesium alloy composite material.

[0116] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 162 W / m·K, a yield strength of 130 MPa, and excellent formability. The metallographic structure of the obtained magnesium alloy composite material is shown in the image below. Figure 3 As shown, by Figure 3It can be seen that the internal structure of the magnesium alloy composite material obtained in Example 1 is very uniform. The carbon thermally conductive particles 10 are uniformly and randomly distributed and have a large content. The magnesium alloy composite material also contains multiple large-particle semi-solid primary α-Mg phases 20 with a size greater than or equal to 10 μm, and multiple small-particle secondary α-Mg phases 30 with a size greater than or equal to 1 μm and less than 10 μm.

[0117] Example 2

[0118] A method for preparing a magnesium alloy composite material, comprising:

[0119] S1. Prepare raw materials according to the following composition of magnesium alloy matrix elements: Zn mass content is 9.6wt.%, Al mass content is 0.4wt.%, La and Ce total mass content is 0.75wt.%, other impurity element mass content is ≤0.1wt.%, and the remainder is Mg; melt the raw materials, cast them at 720℃, and then granulate them to obtain magnesium alloy matrix particles with a particle size of 0.3mm-3mm;

[0120] S2. Take carbon-based thermally conductive particles with a diameter of 10μm-100μm and dry them in an oven at 200℃ for 30min. Then, premix them with thermally conductive metal powder with a diameter of 0.2μm-20μm in a mixer for 15min. Then, add the magnesium alloy matrix particles obtained in step S1 to the mixer and mix for 15min to obtain a uniformly dispersed mixture. The thermally conductive metal powder includes zinc powder, aluminum powder, and copper powder. The mass ratio of the magnesium alloy matrix particles is 85wt%, the sum of the mass ratios of the carbon-based thermally conductive particles and the thermally conductive metal powder is 15%, and the mass ratio of the carbon-based thermally conductive particles to the thermally conductive metal powder is 4:1.

[0121] S3. Add the mixture obtained in step S2 to a semi-solid injection molding machine, store the material at a heating temperature of 615℃, set the screw shearing speed to 120rpm, and then quickly inject the semi-solid mixture into the mold for molding. The cooling time is 6s. Open the mold to obtain a one-time molded high thermal conductivity magnesium alloy composite material.

[0122] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 160 W / m·K, a yield strength of 133 MPa, and excellent formability.

[0123] Example 3

[0124] A method for preparing a magnesium alloy composite material, comprising:

[0125] S1. Prepare raw materials according to the following composition of magnesium alloy matrix elements: Zn mass content is 8.5wt.%, Al mass content is 0.2wt.%, La and Ce total mass content is 0.5wt.%, other impurity element mass content is ≤0.1wt.%, and the remainder is Mg; melt the raw materials, cast them at 720℃, and then granulate them to obtain magnesium alloy matrix particles with a particle size of 0.3mm-3mm;

[0126] S2. Take carbon-based thermally conductive particles with a diameter of 20μm-120μm and dry them in an oven at 200℃ for 30min. Then, premix them with thermally conductive metal powder with a diameter of 0.2μm-20μm in a mixer for 15min. Next, add the magnesium alloy matrix particles obtained in step S1 to the mixer and mix for 15min to obtain a uniformly dispersed mixture. The thermally conductive metal powder includes zinc powder, aluminum powder, and copper powder. The mass ratio of the magnesium alloy matrix particles is 82wt%, the sum of the mass ratios of the carbon-based thermally conductive particles and the thermally conductive metal powder is 18%, and the mass ratio of the carbon-based thermally conductive particles to the thermally conductive metal powder is 4:1.

[0127] S3. Add the mixture obtained in step S2 to a semi-solid injection molding machine, store the material at a heating temperature of 620℃, set the screw shearing speed to 120rpm, and then quickly inject the semi-solid mixture into the mold for molding. The cooling time is 6s. Open the mold to obtain a one-time molded high thermal conductivity magnesium alloy composite material.

[0128] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 164 W / m·K, a yield strength of 141 MPa, and excellent formability.

[0129] Example 4

[0130] A method for preparing a magnesium alloy composite material, comprising:

[0131] S1. Prepare raw materials according to the following composition of magnesium alloy matrix elements: Zn mass content is 8.5wt.%, Al mass content is 0.1wt.%, La and Ce total mass content is 0.8wt.%, other impurity element mass content is ≤0.1wt.%, and the remainder is Mg; melt the raw materials, cast them at 720℃, and then granulate them to obtain magnesium alloy matrix particles with a particle size of 0.3mm-3mm;

[0132] S2. Take carbon-based thermally conductive particles with a diameter of 20μm-120μm and dry them in an oven at 200℃ for 30min. Then, premix them with thermally conductive metal powder with a diameter of 0.2μm-20μm in a mixer for 15min. Next, add the magnesium alloy matrix particles obtained in step S1 to the mixer and mix for 15min to obtain a uniformly dispersed mixture. The thermally conductive metal powder includes copper powder. The mass ratio of the magnesium alloy matrix particles is 90wt%, the sum of the mass ratios of the carbon-based thermally conductive particles and the thermally conductive metal powder is 10%, and the mass ratio of the carbon-based thermally conductive particles to the thermally conductive metal powder is 9:1.

[0133] S3. Add the mixture obtained in step S2 to a semi-solid injection molding machine, store the material at a heating temperature of 620℃, set the screw shearing speed to 120rpm, and then quickly inject the semi-solid mixture into the mold for molding. The cooling time is 5s. Open the mold to obtain a one-time molded high thermal conductivity magnesium alloy composite material.

[0134] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 158 W / m·K, a yield strength of 125 MPa, and excellent formability. The scanning electron microstructure of the magnesium alloy composite material is shown in the figure. Figure 4 As shown, by Figure 4 It can be seen that the magnesium alloy composite material obtained in Example 4 has a uniform composite structure inside, the carbon thermally conductive particles 10 are uniformly and randomly distributed and have a large content. The magnesium alloy composite material also contains multiple large-particle semi-solid primary α-Mg phases 20 with a size greater than or equal to 10 μm, and multiple small-particle secondary α-Mg phases 30 with a size greater than or equal to 1 μm and less than 10 μm.

[0135] Example 5

[0136] The difference from Example 1 is that the mass ratio of magnesium alloy matrix particles is 95 wt%, and the sum of the mass ratios of carbon thermally conductive particles and thermally conductive metal powder is 5%.

[0137] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 164 W / m·K and a yield strength of 141 MPa, and exhibits good formability, although its formability is weaker compared to Example 1.

[0138] Example 6

[0139] The difference from Example 2 is that the mass content of Zn in the magnesium alloy matrix is ​​7 wt.%, the mass content of Al is 0.8 wt.%, and the total mass content of La and Ce is 1.5 wt.%.

[0140] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 141 W / m·K, a yield strength of 123 MPa, and good formability, although its formability is somewhat weakened compared to Example 2.

[0141] Example 7

[0142] The difference from Example 3 is that the mass content of Zn, a constituent element of the magnesium alloy matrix, is 5 wt.%.

[0143] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 168 W / m·K, a yield strength of 136 MPa, and good formability.

[0144] Example 8

[0145] The difference from Example 4 is that the mass ratio of carbon-based thermally conductive particles to thermally conductive metal powder is 12:1.

[0146] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 151 W / m·K and a yield strength of 118 MPa, and exhibits good formability, although its formability is weaker compared to Example 4.

[0147] Example 9

[0148] The difference from Example 4 is that the diameter of the carbon-based thermally conductive particles is 2μm-8μm.

[0149] The magnesium alloy composite material obtained in this embodiment has a thermal conductivity of 146 W / m·K and a yield strength of 115 MPa, and exhibits good formability, although its formability is weaker compared to Example 1.

[0150] Comparative Example 1

[0151] The difference from Example 2 is that the magnesium alloy matrix does not include La and Ce.

[0152] The thermal conductivity of the magnesium alloy composite material obtained in this comparative example is 109 W / m·K, which is relatively low. The yield strength is 120 MPa, which is weaker than that of Example 2.

[0153] Comparative Example 2

[0154] The difference from Example 2 is that carbon-based thermally conductive particles and thermally conductive metal powder are not added; instead, the particles obtained in step S1 are directly added to a semi-solid injection molding machine for semi-solid molding.

[0155] The thermal conductivity of the magnesium alloy composite material obtained in this comparative example is 110 W / m·K, which is relatively low. The yield strength is 105 MPa, and the formability is significantly weaker than that of Example 2.

[0156] Comparative Example 3

[0157] The difference from Example 2 is that in step S2, no thermally conductive metal powder is added, but only carbon thermally conductive particles with a mass ratio of 12% are added.

[0158] The thermal conductivity of the magnesium alloy composite material obtained in this comparative example is 122 W / m·K, and the yield strength is 88 MPa. The thermal conductivity and yield strength are relatively low, and the formability is significantly weakened compared with Example 2.

[0159] Comparative Example 4

[0160] The difference from Example 6 is that the mass content of Al, a constituent element of the magnesium alloy matrix, is 1.3 wt.%.

[0161] The thermal conductivity of the magnesium alloy composite material obtained in this comparative example is 105 W / m·K, which is relatively low. The yield strength is 123 MPa, and the formability is weaker than that of Example 6.

[0162] Performance testing

[0163] Thermal conductivity: The thermal conductivity of the magnesium alloy composites from Examples 1 to 9 and Comparative Examples 1 to 4 was tested at room temperature (25°C). Test method: The thermal diffusivity α (mm²) of the magnesium alloy composites was measured using a laser transient thermal conductivity meter (LFA467HT). 2 / s); The specific heat capacity C of magnesium alloy composites was tested using a three-step method with a differential scanning calorimeter (DSC8000). p (J / (g·K)); The density ρ (g / cm³) of the magnesium alloy composite material was measured by the water displacement method using a hydrometer (ET-320). 3 Based on thermal diffusivity α and specific heat capacity C p Calculate thermal conductivity using density ρ, and thermal conductivity is equal to the product of these three factors.

[0164] Yield strength: The yield strength of the magnesium alloy composites of Examples 1 to 9 and Comparative Examples 1 to 4 were tested according to GB / T 228.1-2010.

[0165] Molding capability: The magnesium alloy composite materials of Examples 1 to 9 and Comparative Examples 1 to 4 were semi-solidly molded into thin-walled parts with a thickness of 0.5 mm in one step to evaluate the molding performance. Figure 5 This is a photograph of a 0.5 mm thick thin-walled part molded from the magnesium alloy composite material of Example 1. Figure 5 As can be seen, the thin-walled part has a complete overall structure without defects such as defects or cold shuts, and zero-degree draft forming at the blanking position is achieved in one casting process.

[0166] The thermal conductivity, yield strength, and formability of the magnesium alloy composite materials obtained in Examples 1 to 9 and Comparative Examples 1 to 4 are shown in Table 1.

[0167] Table 1

[0168]

[0169]

[0170] As shown in Table 1, the magnesium alloy composite materials obtained in Examples 1 to 9 of this application possess high thermal conductivity, good formability, and high yield strength. The thermal conductivity is all above 140 W / m·K, the formability is all above two stars, and the yield strength is all above 110 MPa.

[0171] Comparing Example 2 with Comparative Examples 1 to 3, and Example 6 with Comparative Example 4, it can be seen that the embodiments of this application prepare magnesium alloy composite materials by selecting magnesium alloy matrix particles with suitable component ratios and introducing non-metallic thermally conductive particles and thermally conductive metal powders. Under the synergistic effect of each component, the resulting magnesium alloy composite material has high thermal conductivity, good formability and high yield strength.

[0172] Comparing Examples 1 and 5, it can be seen that the total content of non-metallic thermally conductive particles and thermally conductive metal powder is higher, which is more conducive to improving thermal conductivity and molding performance.

[0173] Comparing Examples 2 and 6, it can be seen that controlling the aluminum content in the matrix components to a relatively lower value is more conducive to improving thermal conductivity and molding performance.

[0174] Comparing Examples 3 and 7, it can be seen that controlling the zinc content in the matrix constituent elements to a suitable value is beneficial to better balance high thermal conductivity and high yield strength.

[0175] Comparing Examples 4 and 8, it can be seen that the content of thermally conductive metal powder is higher than that of non-metallic thermally conductive particles, which is more conducive to the dispersion of non-metallic thermally conductive particles, thereby improving thermal conductivity and molding ability.

[0176] Comparing Examples 4 and 9, it can be seen that controlling the particle size of non-metallic thermal conductive particles to a relatively larger value is more conducive to the dispersion of non-metallic thermal conductive particles, thereby improving thermal conductivity and molding ability.

[0177] It should be understood that the use of the terms "first," "second," and various numerical designations in this document is merely for descriptive convenience and is not intended to limit the scope of this application.

[0178] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after it are in an "or" relationship.

[0179] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0180] In this application, "-" indicates a range value, including the endpoint values ​​at both ends. For example, the value of a can be 0.5-15, meaning that the value of a can be between 0.5 and 15, and includes the endpoint values ​​of 0.5 and 15.

[0181] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

Claims

1. A magnesium alloy composite material, characterized in that, The magnesium alloy composite material includes magnesium alloy matrix elements, non-metallic thermally conductive particles, and thermally conductive metallic elements, wherein the non-metallic thermally conductive particles are dispersed within the magnesium alloy composite material. The magnesium alloy matrix comprises, by total mass, 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities.

2. The magnesium alloy composite material as described in claim 1, characterized in that, In the magnesium alloy matrix, the mass percentage of Al is in the ratio of the sum of the mass percentages of La and Ce to 1:(1-15).

3. The magnesium alloy composite material as described in claim 1 or 2, characterized in that, The magnesium alloy matrix also includes one or more of the following elements: Y, Mn, Sn, Gd, Ca, and Zr.

4. The magnesium alloy composite material according to any one of claims 1-3, characterized in that, In the magnesium alloy composite material, the mass percentage of non-metallic thermally conductive particles is 5%-30%.

5. The magnesium alloy composite material according to any one of claims 1-4, characterized in that, In the magnesium alloy composite material, the mass percentage of thermally conductive metal elements is 0.1%-6%.

6. The magnesium alloy composite material according to any one of claims 1-5, characterized in that, The mass ratio of the non-metallic thermally conductive particles to the thermally conductive metal element is (2-12):

1.

7. The magnesium alloy composite material according to any one of claims 1-6, characterized in that, In the magnesium alloy composite material, the sum of the mass percentages of non-metallic thermally conductive particles and thermally conductive metal elements is 5%-20%, and the mass percentage of the constituent elements of the magnesium alloy matrix is ​​80%-95%.

8. The magnesium alloy composite material according to any one of claims 1-7, characterized in that, The non-metallic thermally conductive particles include one or more of aluminum nitride particles, graphite particles, diamond particles, and graphene particles.

9. The magnesium alloy composite material according to any one of claims 1-8, characterized in that, The particle size of the non-metallic thermally conductive particles is 1μm-150μm.

10. The magnesium alloy composite material according to any one of claims 1-9, characterized in that, The thermally conductive metal element includes one or more metal elements that, when introduced individually or jointly into the magnesium alloy composite material, result in a magnesium lattice volume change of less than 5% and have a thermal conductivity higher than that of magnesium.

11. The magnesium alloy composite material according to any one of claims 1-10, characterized in that, The thermally conductive metal element includes one or more of nickel, copper, aluminum, silver, and zinc.

12. The magnesium alloy composite material according to any one of claims 1-11, characterized in that, At least a portion of the thermally conductive metal elements form a first intermetallic compound with the constituent elements of the magnesium alloy matrix; at least a portion of the first intermetallic compound is distributed at the interface between the magnesium alloy matrix and the non-metallic thermally conductive particles.

13. The magnesium alloy composite material according to any one of claims 1-12, characterized in that, The magnesium alloy composite material includes a secondary α-Mg phase and a primary α-Mg phase dispersed within the secondary α-Mg phase.

14. The magnesium alloy composite material as described in claim 13, characterized in that, The primary α-Mg phase has a particle size of 10 μm-100 μm.

15. The magnesium alloy composite material as described in claim 13 or 14, characterized in that, The area ratio of the primary α-Mg phase in any cross section of the magnesium alloy composite material is 5%-50%.

16. The magnesium alloy composite material according to any one of claims 13-15, characterized in that, The secondary α-Mg phase has a particle size greater than or equal to 1 μm and less than 10 μm.

17. The magnesium alloy composite material according to any one of claims 1-16, characterized in that, The thermal conductivity of the magnesium alloy composite material is greater than or equal to 140 W / (m·K).

18. A method for preparing a magnesium alloy composite material, characterized in that, include: Non-metallic thermally conductive particles, thermally conductive metal element powder, and magnesium alloy matrix particles are mixed to obtain a uniformly dispersed mixture; the thermally conductive metal element in the thermally conductive metal element powder can form a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles; the magnesium alloy matrix particles include the following constituent elements by mass percentage: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities; The mixture was injection molded using a semi-solid injection molding process to obtain a magnesium alloy composite material.

19. The preparation method according to claim 18, characterized in that, The non-metallic thermally conductive particles are added at a total mass percentage of 5%-30% in the magnesium alloy composite material; the thermally conductive metal element powder is added at a total mass percentage of 0.1%-6% in the magnesium alloy composite material.

20. The preparation method according to claim 18 or 19, characterized in that, The material storage temperature for injection molding is 595℃-620℃.

21. The preparation method according to any one of claims 18-20, characterized in that, The temperature of the injection molding mold is 250℃-320℃.

22. The preparation method according to any one of claims 18-21, characterized in that, The screw shearing speed for injection molding is 100 rpm-200 rpm.

23. A powder composition for use in semi-solid molding of magnesium alloy composite materials, characterized in that, The powder composition comprises magnesium alloy matrix particles, non-metallic thermally conductive particles, and thermally conductive metal element powder; the thermally conductive metal element in the thermally conductive metal element powder is capable of forming a first intermetallic compound with the constituent elements of the magnesium alloy matrix particles; the magnesium alloy matrix particles comprise the following constituent elements by mass percentage: 87.5%-95% Mg, 4%-10% Zn, 0.05%-1% Al, a total of 0.05%-2% La and Ce, and ≤0.2% unavoidable impurities.

24. A structural component, characterized in that, The structural component includes the magnesium alloy composite material according to any one of claims 1-17 or the magnesium alloy composite material prepared by the preparation method according to any one of claims 18-23.

25. A device, characterized in that, Includes the structural component as described in claim 24.

26. A vehicle, characterized in that, Includes the structural component as described in claim 24.

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