Magnesium alloy, magnesium alloy shell and electronic equipment

Abstract

The invention provides a magnesium alloy, a magnesium alloy shell and electronic equipment. The magnesium alloy comprises the following components in percentage by weight: 2.5%-4.5% of aluminum, 0.5%-1.0% of zinc, 0.2%-0.8% of manganese, 0.01%-1.0% of titanium, 0.01%-0.5% of antimony and the balance of magnesium, additive elements and inevitable impurities, the additive element is a lanthanum-cerium mixed element, and the total weight percentage of the lanthanum element and the cerium element is 0.5%-1.5%. The magnesium alloy can be applied to a magnesium alloy shell, a small amount of low-price mixed rare earth (La / Ce) is added into an alloy of an Mg-Al-Zn system with the low Al content, the refining effect of trace Ti and Sb elements is matched, the corrosion resistance of the magnesium alloy can be greatly improved, meanwhile, the use amount of the rare earth element and the aluminum element is reduced, the manufacturing cost is reduced, and the service life of the magnesium alloy is prolonged. The method is suitable for mass production of electronic products.

Description

Technical Field

[0001] This application relates to the field of metal materials, and more specifically, to a magnesium alloy, a magnesium alloy housing, and an electronic device. Background Art

[0002] Under the trend of lightweight of electronic products, lightweight magnesium alloy materials are increasingly applied to the housings of electronic products. However, due to reasons such as low electrode potential and poor corrosion resistance of magnesium alloys, the available surface treatment processes are single. Currently, only the conventional spraying process is available, and the full coverage of the paint layer cannot highlight the metallic texture of the magnesium alloy substrate itself. In addition, when the conventional magnesium alloy high-gloss solution is tested in a humid and hot environment, there are many problems such as corrosion discoloration, paint layer blistering and peeling, which cannot meet the use requirements of electronic products.

[0003] Therefore, there is an urgent need to provide a magnesium alloy material with strong corrosion resistance to solve the corrosion-related problems of products caused by insufficient corrosion resistance of the substrate in various environments such as salt spray, high temperature and high humidity, and to achieve a high-gloss effect of the product with a transparent coating while meeting the requirements of reliability tests. Summary of the Invention

[0004] This application provides a magnesium alloy, a magnesium alloy housing, and an electronic device, which can improve the corrosion resistance of the magnesium alloy, achieve a high-gloss effect of the magnesium alloy housing while improving its corrosion resistance, and is suitable for mass production of electronic products.

[0005] In a first aspect, a magnesium alloy is provided. The magnesium alloy comprises the following components in weight percentage: aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, and the balance is magnesium, additive elements, and impurities; the additive elements include a lanthanum-cerium mixed element, and the total weight percentage of the lanthanum element and the cerium element is: 0.5% - 1.5%, wherein the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.5.

[0006] Among them, the additive elements may include a lanthanum-cerium mixed rare earth element. Exemplarily, the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.5. It should be understood that the mixed rare earth is lower in price than the pure rare earth. By using the lanthanum-cerium mixed rare earth, the cost is lower compared to pure lanthanum and pure cerium.

[0007] In the embodiments of the present application, in an alloy of the Mg-Al-Zn system with a low Al content, a small amount of low-cost mixed rare earths (La / Ce) is added, and in combination with the refinement and modification effects of trace amounts of Ti and Sb elements, a large number of second phases with low corrosion potential and uniform distribution are formed in the material. On the one hand, the tendency of galvanic corrosion is reduced. On the other hand, a uniform and continuous dense oxide film is quickly formed during the corrosion process of the material, hindering further corrosion from occurring, and the corrosion resistance of the material is greatly improved. At the same time, the presence of the Mg-Sb second phase in the material can effectively hinder the grain growth during the hot extrusion process of the ingot, so that the produced deformed magnesium material still has a fine grain structure, giving full play to the beneficial effect of rare earth elements in improving the corrosion resistance of the material and achieving the purpose of low content and high corrosion resistance. In addition, the fine grain structure in the deformed magnesium material is more conducive to the CNC drilling tool cutting the material, reducing the micro-plastic deformation at the tip of the tool and obtaining a high-gloss surface with better surface finish. In short, under the coupling action between trace rare earth elements and refinement and modification elements, the material has less alloying element usage, high plastic deformation efficiency, low production cost, and is suitable for mass production and application of electronic products (such as magnesium alloy casings or casings of electronic devices).

[0008] In a possible implementation manner, the added element further includes tin, and the weight percentage content of the tin is 0.1% to 1.0%.

[0009] In the embodiments of the present application, by adding Sn element, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, so that the corrosion resistance of the prepared deformed magnesium material is further improved.

[0010] In a possible implementation manner, the magnesium alloy includes the following components by weight percentage: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum-cerium: 0.5% to 1.0%. Among them, lanthanum-cerium represents a lanthanum-cerium mixed element, and the total weight percentage content of lanthanum and cerium is 0.5% to 1.0%.

[0011] In a possible implementation manner, the magnesium alloy includes the following components by weight percentage: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum-cerium: 0.5% to 1.0%, tin: 0.5% to 1.0%. Among them, lanthanum-cerium represents a lanthanum-cerium mixed element, and the total weight percentage content of lanthanum and cerium is 0.5% to 1.0%.

[0012] In a possible implementation manner, based on the total weight of the magnesium alloy, the total amount of impurities such as iron, copper, nickel, and silicon does not exceed 0.015%, and among them, the content of iron does not exceed 0.005%.

[0013] It should be understood that in order to improve the corrosion resistance of the magnesium alloy substrate, the impurity content in the magnesium alloy substrate should not be too high. For example, the total amount of impurities does not exceed 0.015%. Among them, the content of Fe element in the impurities has a greater impact on the corrosion resistance of the magnesium alloy. Therefore, the content of Fe element in the magnesium alloy should not be too high and should not exceed 0.005% of the total weight of the magnesium alloy.

[0014] In a second aspect, a magnesium alloy housing is provided. The magnesium alloy housing includes: a housing substrate, which is a magnesium alloy substrate; a transition protective layer located on the surface of the housing substrate; a colored coating located on a side of the transition protective layer away from the housing substrate, and at least part of the transition protective layer and the colored coating do not cover the housing substrate; and a transparent coating at least covering a surface of the housing substrate not covered by the transition protective layer and the colored coating. Among them, the magnesium alloy substrate includes the following components by weight percentage: aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, and the balance is magnesium, additive elements and impurities; the additive elements include a lanthanum-cerium mixed element, and the total weight percentage of the lanthanum element and the cerium element is: 0.5% - 1.5%, wherein the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.5.

[0015] It should be understood that at least part of the transition protective layer and the colored coating do not cover the housing substrate, so that part of the housing substrate is exposed, and the exposed part of the housing substrate is covered by the transparent coating. That is to say, the transparent coating at least covers the surface of the housing substrate not covered by the transition protective layer and the colored coating, thereby realizing a partial high-gloss effect of the magnesium alloy housing and making the magnesium alloy housing have a strong metallic texture.

[0016] In addition, a transparent coating can also be formed at a preset position according to product requirements to improve the aesthetics of the magnesium alloy housing. Exemplarily, the transparent coating can be located on the side of the magnesium alloy housing, at the corner position of the magnesium alloy housing, etc. The present application does not limit this.

[0017] In addition, in order to improve the corrosion resistance of the magnesium alloy housing, the housing substrate can adopt a corrosion-resistant magnesium alloy substrate. By adding a small amount of low-cost mixed rare earth (La / Ce) and combining with the refinement and modification effects of trace elements Ti and Sb in an alloy of the Mg-Al-Zn system with a low Al content, a large number of second phases with low corrosion potential and uniform distribution are generated in the material. On the one hand, the tendency of galvanic corrosion is reduced. On the other hand, a uniform and continuous dense oxide film is quickly formed on the substrate during the corrosion process, hindering further corrosion, and the corrosion resistance of the material is greatly improved. At the same time, the presence of the Mg-Sb second phase in the material can effectively hinder the grain growth during the hot extrusion of the ingot, so that the produced deformed magnesium material still has a fine grain structure, fully exerting the beneficial effect of rare earth elements in improving the corrosion resistance of the material and achieving the purpose of low content and high corrosion resistance. In addition, the fine grain structure in the deformed magnesium material is more conducive to the CNC drilling tool cutting the material, reducing the micro-plastic deformation at the tip of the tool and obtaining a high-gloss surface with better surface finish. In short, under the coupling effect between trace rare earth elements and refinement and modification elements, the material has less alloying element consumption, high plastic deformation efficiency, low production cost, and is suitable for batch production of magnesium alloy housings.

[0018] That is to say, the magnesium alloy housing provided by the embodiment of the present application solves the corrosion-related problems of the product in various environments such as salt spray and high temperature and high humidity caused by insufficient corrosion resistance of the substrate by adopting a corrosion-resistant magnesium alloy substrate, and realizes the high-gloss effect of the product while meeting the requirements of reliability tests by matching with a transparent coating.

[0019] In a possible implementation manner, the transition protective layer has a first through groove; the colored coating has a second through groove, and the projection of the second through groove on the housing substrate along a first direction at least partially overlaps with the projection of the first through groove on the housing substrate along the first direction, and the first direction is the thickness direction of the magnesium alloy housing; the transparent coating includes a first part, and the first part of the transparent coating fills the first through groove and the second through groove and adheres to the surface of the housing substrate.

[0020] Exemplarily, the thickness of the first part of the transparent coating is the same as or approximately the same as the thickness of the transition protective layer and the colored coating. That is to say, the surface of the first part of the transparent coating away from the housing substrate is substantially flush with the surface of the colored coating away from the housing substrate (i.e., the height difference is within a certain range).

[0021] In the embodiments of the present application, the magnesium alloy housing can be processed by drilling and electrophoretic coating, so that the transition protective layer on the housing substrate has a first through groove, the colored coating on the housing substrate has a second through groove, and at least part of the first through groove and the second through groove overlap, so that the surface of the housing substrate is exposed. The exposed part of the housing substrate can be filled with a transparent coating, so as to achieve a local high-gloss effect on the magnesium alloy housing and endow the magnesium alloy housing with a strong metallic texture.

[0022] Exemplarily, for the processing and production requirements and to achieve a better high-gloss effect, along the first direction, the thickness of the first part of the transparent coating is less than or equal to 60 μm.

[0023] In a possible implementation manner, the transparent coating further includes a second part, and the second part of the transparent coating covers the side of the colored coating away from the housing substrate.

[0024] In the embodiments of the present application, the magnesium alloy housing can be processed by drilling and spraying, so that the transition protective layer on the housing substrate has a first through groove, the colored coating on the housing substrate has a second through groove, and at least part of the first through groove and the second through groove overlap, so that the surface of the housing substrate is exposed. The exposed part of the housing substrate and the entire surface of the colored coating can be covered with a transparent coating, so as to also achieve a local high-gloss effect on the magnesium alloy housing and endow the magnesium alloy housing with a strong metallic texture.

[0025] Exemplarily, for the processing and production requirements and to achieve a better high-gloss effect, along the first direction, the thickness of the second part of the transparent coating is less than or equal to 30 μm.

[0026] In a possible implementation manner, the housing substrate includes a bent portion, the bent portion of the housing substrate is not covered by the transition protective layer and the colored coating, and the transparent coating covers the bent portion of the housing substrate. This bent portion can be a chamfered part (such as a rounded corner or an inclined chamfer).

[0027] Exemplarily, the housing substrate may include a first side surface and a second side surface, the first side surface and the second side surface intersect at a first side edge, and the first side edge can be cut to form a first surface. That is to say, the first side surface and the second side surface intersect at the first surface, and the first surface of the housing substrate is exposed. The transparent coating can cover the intersecting surface (i.e., the first surface) of the first side surface and the second side surface. In this way, not only can a high-gloss effect be achieved on the surface of the housing substrate, but also a local high-gloss effect can be achieved on the side surface and the first surface of the housing substrate, thereby improving the aesthetics of the electronic product.

[0028] In a possible implementation manner, the transition protective layer can be a chemical conversion film and / or a micro-arc oxidation film.

[0029] In a possible implementation, the composition of the magnesium alloy substrate further includes tin, and the weight percentage of the tin is 0.1% - 1.0%.

[0030] In the embodiments of the present application, by adding Sn element into the magnesium alloy substrate, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, so that the corrosion resistance of the prepared deformed magnesium material is further improved.

[0031] In a possible implementation, the magnesium alloy substrate includes the following components by weight percentage: aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%. Among them, lanthanum - cerium represents a lanthanum - cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% - 1.0%.

[0032] In a possible implementation, the magnesium alloy substrate includes the following components by weight percentage: aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%, tin: 0.5% - 1.0%. Among them, lanthanum - cerium represents a lanthanum - cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% - 1.0%.

[0033] In a possible implementation, based on the total weight of the magnesium alloy substrate, the total amount of impurities such as iron, copper, nickel, and silicon does not exceed 0.015%, and among them, the content of iron does not exceed 0.005%.

[0034] It should be understood that in order to improve the corrosion resistance of the magnesium alloy substrate, the impurity content in the magnesium alloy substrate should not be too much, such as the total amount of impurities does not exceed 0.015%. Among them, the content of Fe element in the impurities has a greater impact on the corrosion resistance of the magnesium alloy. Therefore, the content of Fe element in the magnesium alloy should not be too high and should not exceed 0.005% of the total weight of the magnesium alloy.

[0035] In the third aspect, a preparation method of a magnesium alloy shell is provided, and the preparation method includes the following steps:

[0036] Melt pure magnesium, pure aluminum, and manganese chloride raw materials at 720°C. After the melt temperature stabilizes at 720°C, add lanthanum-cerium alloy and pure antimony. Stir the melt after melting for 30 minutes. Then raise the temperature of the melt to 800°C, add aluminum-titanium master alloy, and keep it warm for 30 minutes. Then add refining agent, solvent, etc. to remove impurities for 60 minutes, and pour the melt into a mold to obtain a magnesium alloy casting rod. Among them, the weight percentage of each component is as follows: aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, and the rest is magnesium, added elements, and inevitable impurities; the added element is a lanthanum-cerium mixed element, and the total weight percentage of lanthanum element and cerium element is: 0.5% - 1.5%, among which, the weight ratio of lanthanum element to cerium element is 1.5 - 2.5;

[0037] Process the magnesium alloy casting rod into a casting rod with specified dimensions, homogenize it at 350 - 400°C for 20 hours, and then prepare a shell substrate under the condition of an extrusion ratio of 30:1. The shell substrate is a corrosion-resistant magnesium alloy substrate;

[0038] The shell substrate is processed by CNC to obtain a shell with the required structural shape. A transition protective layer is formed on one side of the shell substrate through a chemical conversion process and / or a micro-arc oxidation process; then a colored coating is formed on the side of the transition protective layer away from the shell substrate by a spraying process;

[0039] Drill and cut in a specified area on the surface of the magnesium alloy shell so that at least part of the transition protective layer and the colored coating do not cover the shell substrate, and the surface of the shell substrate is exposed to form a high-gloss area with a metallic luster;

[0040] A transparent coating is formed on the high-gloss area by an electrophoresis process and / or a spraying process. The transparent coating adheres at least to the surface of the shell substrate not covered by the transition protective layer and the colored coating.

[0041] It should be understood that for the magnesium alloy raw materials used in this application, by adding a small amount of low-cost mixed rare earth (La / Ce) and matching trace elements of Ti and Sb for refinement and modification in the alloy of the Mg-Al-Zn system with a low Al content, a large number of second phases with low corrosion potential and uniform distribution are generated in the material. On the one hand, the tendency of galvanic corrosion is reduced. On the other hand, a uniform and continuous dense oxide film is rapidly formed during the corrosion process of the material, hindering the further occurrence of corrosion, and the corrosion resistance of the material is greatly improved. At the same time, the presence of the Mg-Sb second phase in the material can effectively hinder the grain growth during the hot extrusion of the ingot, so that the produced deformed magnesium material still has a fine grain structure, fully exerting the beneficial effect of rare earth elements in improving the corrosion resistance of the material, and achieving the purpose of low content and high corrosion resistance. In addition, the fine grain structure in the deformed magnesium material is more conducive to the CNC drilling tool cutting the material, reducing the micro-plastic deformation at the tip of the tool and obtaining a high-gloss surface with better smoothness. In short, under the coupling effect between trace rare earth elements and refinement and modification elements, the material has less alloying element consumption, high plastic deformation efficiency, low production cost, and is suitable for mass production and application of electronic products (such as magnesium alloy casings or casings of electronic devices).

[0042] In the embodiment of this application, by using a corrosion-resistant magnesium material and a one-time transparent coating process (such as an electrophoresis process and / or a spraying process), the local high-gloss effect of the magnesium alloy casing can be achieved, with a strong metallic texture. And the obtained magnesium alloy casing is subjected to a salt spray test for 120H, without problems of corrosion and blistering, and the substrate has excellent corrosion resistance. It solves the problems of corrosion discoloration, paint peeling, blistering, etc. during the testing process of magnesium high-gloss products, meets the reliability requirements of the products, and is suitable for mass production of large-size casings used in electronic products.

[0043] In a possible implementation manner, drilling is performed on a specified area on the surface of the magnesium alloy casing, so that at least part of the transition protective layer and the colored coating do not cover the casing substrate, and the surface of the casing substrate is exposed, forming a high-gloss area with a metallic luster. Specifically, it may include: drilling is performed on a specified area on the surface of the magnesium alloy casing, a first through groove is formed on the transition protective layer, a second through groove is formed on the colored coating, and the projection of the second through groove on the casing substrate along a first direction at least partially overlaps with the projection of the first through groove on the casing substrate along the first direction. The first direction is the thickness direction of the magnesium alloy casing, so that the surface of the casing substrate is exposed, forming a high-gloss area with a metallic luster;

[0044] A transparent coating is formed on the high-gloss area by using an electrophoresis process and / or a spraying process. The transparent coating at least adheres to the surface of the casing substrate not covered by the transition protective layer and the colored coating. Specifically, it may include: a transparent coating is formed on the high-gloss area by using an electrophoresis process and / or a spraying process. At least part of the transparent coating passes through the first through groove and the second through groove and adheres to the surface of the casing substrate.

[0045] In a possible implementation, forming a transparent coating on the high-gloss area by electrophoresis process includes: dipping the diamond-cut magnesium alloy housing into an electrophoresis tank, and under the condition of electrification (voltage is 120V, time is 30s), electrophoretic paint adheres to the high-gloss area to form a transparent coating.

[0046] Exemplarily, along the first direction, the thickness of the transparent coating is less than or equal to 60μm.

[0047] Exemplarily, based on the total weight of the magnesium alloy, the components and weight percentages of the corrosion-resistant magnesium alloy substrate are: 4.5wt.% Al, 0.7wt.% Zn, 0.5wt.% Mn, 0.7wt.% La / Ce, 0.2wt.% Ti, 0.4wt.% Sb, and the rest are Mg and inevitable trace elements.

[0048] In this implementation, by using corrosion-resistant magnesium material and a single transparent coating process (such as electrophoresis process), the local high-gloss effect of the magnesium alloy housing can be achieved, with a strong metallic texture. And the obtained magnesium alloy housing is subjected to a salt spray test for 120H, without corrosion and blistering problems, the substrate has excellent corrosion resistance, and the corrosion rate is 0.181mg / (cm 2 *d). It solves the problems of corrosion, discoloration, paint peeling, blistering, etc. during the testing process of magnesium high-gloss products, and meets the product reliability requirements.

[0049] In addition, uniformly fine second phases Mg-RE / Mg-Al-RE can be formed in the housing substrate, which can reduce the potential difference with the Mg matrix, thereby reducing the corrosion tendency; at the same time, the second phases are uniformly distributed in the matrix, improving the overall corrosion resistance. The corrosion-resistant magnesium alloy provided by this application has good corrosion resistance and high extrusion efficiency, and is suitable for mass production of large-size housings used in electronic products.

[0050] In another possible implementation, forming a transparent coating on the high-gloss area by spraying process includes: for the diamond-cut magnesium alloy housing, spraying a transparent paint layer by spraying process to form a transparent coating. The transparent coating can include a first part and a second part. The first part of the transparent coating passes through the first through groove and the second through groove and adheres to the surface of the housing substrate; the second part of the transparent coating covers the side of the colored coating away from the housing substrate.

[0051] Exemplarily, along the first direction, the thickness of the first part of the transparent coating is less than or equal to 60μm, and the thickness of the second part of the transparent coating is less than or equal to 30μm.

[0052] Exemplarily, based on the total weight of the magnesium alloy, the components and weight percentages of the corrosion-resistant magnesium alloy substrate are: 3.5 wt.% Al, 0.7 wt.% Zn, 0.5 wt.% Mn, 0.7 wt.% La / Ce, 0.2 wt.% Ti, 0.4 wt.% Sb, and the balance is Mg and inevitable trace elements.

[0053] In this implementation, by using a corrosion-resistant magnesium material and a one-time transparent coating process (such as a spraying process), a local high-gloss effect of the magnesium alloy housing 200 can be achieved, with a strong metallic texture. And the obtained magnesium alloy housing is subjected to a salt spray test for 120H, without corrosion and blistering problems. The substrate has excellent corrosion resistance, and the corrosion rate is 0.255 mg / (cm 2 *d). It solves the problems of corrosion discoloration, paint peeling, blistering, etc. during the testing process of magnesium high-gloss products, and meets the reliability requirements of the products.

[0054] In addition, uniformly fine second phases Mg-RE / Mg-Al-RE can be formed in the shell substrate, which can reduce the potential difference with the Mg matrix, thereby reducing the corrosion tendency; at the same time, the second phases are uniformly distributed in the matrix, improving the overall corrosion resistance. The corrosion-resistant magnesium alloy provided by this application has good corrosion resistance and high extrusion efficiency, and is suitable for mass production of large-size housings used in electronic products.

[0055] It should be noted that when the electrophoretic process is used to form the transparent coating, the baking temperature of the electrophoretic transparent coating is 160 - 180 °C. When the spraying process is used to form the transparent coating, the baking temperature of the sprayed transparent coating is 80 - 100 °C.

[0056] In a possible implementation, the transparent coating covers at least the intersection of two adjacent surfaces of the shell substrate.

[0057] Exemplarily, the shell substrate may include a first side and a second side. The side where the first side and the second side intersect is cut to form a first surface. That is to say, the first side and the second side intersect at the first surface, and the first surface of the shell substrate is exposed. The transparent coating can cover the intersecting surface (i.e., the first surface) of the first side and the second side. In this way, not only can a high-gloss effect be achieved on the surface of the shell substrate, but also a local high-gloss effect can be achieved on the side and the first surface of the shell substrate, thereby improving the aesthetics of the electronic product.

[0058] In a possible implementation, the transition protection layer can be a chemical conversion film and / or a micro-arc oxidation film.

[0059] In a possible implementation, while adding pure antimony, pure tin can also be added, so that the composition of the made corrosion-resistant magnesium alloy substrate further includes tin, and the weight percentage content of the tin is 0.1% - 1.0%.

[0060] In the embodiments of the present application, by adding Sn to the corrosion-resistant magnesium alloy substrate, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation of the ingot, so that the corrosion resistance of the prepared deformed magnesium material is further improved.

[0061] In a possible implementation, the corrosion-resistant magnesium alloy substrate includes the following components in weight percentage: aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%. Among them, lanthanum - cerium represents a lanthanum - cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% - 1.0%.

[0062] In a possible implementation, the corrosion-resistant magnesium alloy substrate includes the following components in weight percentage: aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%, tin: 0.5% - 1.0%. Among them, lanthanum - cerium represents a lanthanum - cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% - 1.0%.

[0063] In a possible implementation, based on the total weight of the corrosion-resistant magnesium alloy substrate, the total amount of inevitable impurities such as iron, copper, nickel, and silicon does not exceed 0.015%, and among them, the content of iron does not exceed 0.005%.

[0064] It should be understood that in order to improve the corrosion resistance of the magnesium alloy substrate, the impurity content in the magnesium alloy substrate should not be too much, such as the total amount of impurities does not exceed 0.015%. Among them, the content of the Fe element in the impurities has a greater impact on the corrosion resistance of the magnesium alloy. Therefore, the content of the Fe element in the magnesium alloy should not be too high and should not exceed 0.005% of the total weight of the magnesium alloy.

[0065] Fourthly, an electronic device is provided. The electronic device includes a magnesium alloy housing as in any one of the second aspect or the implementations of the second aspect; or, the electronic device includes a magnesium alloy housing, and the magnesium alloy housing is made by using the preparation method as in any one of the third aspect or the implementations of the third aspect.

[0066] Exemplarily, the electronic device can be a device with a housing, such as mobile terminals including mobile phones, wearable devices, smart watches, tablet computers, e-readers, notebook computers, laptop computers, mobile computers, augmented reality devices, virtual reality devices, and handheld game consoles, etc. The present application does not make any limitations thereto.

[0067] Among them, the beneficial effects of the fourth aspect can refer to the second aspect or the third aspect, which will not be elaborated here. Description of the Drawings

[0068] Figure 1 is a microstructural diagram of a magnesium alloy material provided by an embodiment of the present application.

[0069] Figure 2 is a schematic cross-sectional structure diagram of a magnesium alloy housing provided by an embodiment of the present application.

[0070] Figure 3 is a schematic cross-sectional structure diagram of another magnesium alloy housing provided by an embodiment of the present application.

[0071] Figure 4 is a schematic flow chart of a method for preparing a magnesium alloy housing provided by an embodiment of the present application.

[0072] Figure 5 is a schematic flow chart of another method for preparing a magnesium alloy housing provided by an embodiment of the present application. Detailed Embodiments

[0073] Next, the technical solutions in the present application will be described with reference to the accompanying drawings.

[0074] In the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. Additionally, in the description of the embodiments of the present application, "a plurality" means two or more, "at least one" and "one or more" mean one, two, or more than two. The singular forms "a", "one kind", "the", "above-mentioned", "this", and "this one" are also intended to include expressions such as "one or more" unless there is a clear contrary indication in the context. The magnitudes of the serial numbers of the following processes do not mean the order of execution. The execution order of each process should be determined by its function and internal logic and should not constitute any limitation to the implementation process of the embodiments of the present application. For example, in the embodiments of the present application, the words such as "110", "120", "130", etc. are only identifiers for convenience of description and do not limit the order of execution steps.

[0075] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0076] In the description of the embodiments of the present application, the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is defined with respect to the orientation or position in which the components in the drawings are schematically placed. It should be understood that these directional terms are relative concepts, which are used for relative description and clarification, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. It can change accordingly with the change of the orientation in which the components in the drawings are placed, and thus cannot be understood as a limitation to the present application.

[0077] Under the trend of lightweight of electronic products, lightweight magnesium alloy materials are increasingly applied to the casings of electronic products. However, the corrosion resistance of magnesium alloys is poor. Compared with other metal materials, magnesium and its alloys have relatively active chemical properties, with strong chemical and electrochemical activities, and their standard electrode potential is relatively low (-2.37V). Coupled with the fact that their oxide films are generally porous and loose, they cannot form an effective protective film on the magnesium alloy matrix, so they are easily oxidized. Severe corrosion is extremely likely to occur in a humid environment. Therefore, for magnesium alloys, improving their corrosion resistance is one of the key factors for expanding their applications.

[0078] Currently, in order to improve the corrosion resistance of magnesium alloy materials, generally a relatively high content of aluminum elements and rare earth elements will be added to form a dense oxide film during the oxidation process, thereby hindering further corrosion. However, when the aluminum content is high, the plastic deformation ability of the sheet decreases, and the extrusion production efficiency is low, resulting in high costs; rare earth elements are expensive, and the material cost is high.

[0079] In addition, due to reasons such as low electrode potential and poor corrosion resistance of magnesium alloys, the available surface treatment processes are single. Currently, only the conventional spraying process is available, and the full coverage of the paint layer cannot highlight the metallic texture of the magnesium alloy substrate itself. Moreover, when the conventional high-gloss magnesium alloy solution is tested in a humid and hot environment, there are many problems such as corrosion discoloration, paint layer blistering, and peeling, which cannot meet the applicable requirements of electronic products.

[0080] Therefore, there is an urgent need to provide a magnesium alloy material with strong corrosion resistance to solve the corrosion-related problems of products caused by insufficient corrosion resistance of the base material in various environments such as salt spray, high temperature and high humidity, and to achieve a high-gloss effect of the product while meeting the reliability test requirements with a transparent coating.

[0081] In view of this, the present application provides a magnesium alloy, a magnesium alloy housing, and an electronic device, which can improve the corrosion resistance of the magnesium alloy, achieve a high-gloss effect of the magnesium alloy housing while improving its corrosion resistance, and are suitable for mass production of electronic products.

[0082] The magnesium alloy provided by the embodiments of the present application may specifically include the following components in weight percentages: aluminum (Al): 2.5% - 4.5%, zinc (Zn): 0.5% - 1.0%, manganese (Mn): 0.2% - 0.8%, titanium (Ti): 0.01% - 1.0%, antimony (Sb): 0.01% - 0.5%, and the rest is magnesium (Mg), additive elements, and inevitable impurities; the additive element is a mixed element of lanthanum (La) and cerium (Ce), and the total weight percentage of the lanthanum (La) element and the cerium (Ce) element is: 0.5% - 1.5%, wherein the weight ratio of the lanthanum (La) element to the cerium (Ce) element is 1.5 - 2.5.

[0083] Among them, the additive element can be a lanthanum-cerium mixed rare earth element. It should be understood that the mixed rare earth is lower in price than pure rare earth. By using the lanthanum-cerium mixed rare earth, the cost is lower compared to pure lanthanum and pure cerium.

[0084] The inventors of the present application have proved through a large number of experiments that by adding a small amount of low-cost mixed rare earth (La / Ce) and combining with the refinement and modification effects of trace amounts of Ti and Sb elements, a large number of second phases with low corrosion potential and uniform distribution are generated in the material; on the one hand, the tendency of galvanic corrosion is reduced, and on the other hand, a uniform, continuous, and dense oxide film is quickly formed on the material during the corrosion process, hindering further corrosion, and the corrosion resistance of the material is greatly improved. At the same time, the presence of the Mg-Sb second phase in the material can effectively hinder the grain growth during the hot extrusion of the ingot, so that the produced deformed magnesium material still has a fine grain structure, giving full play to the beneficial effect of rare earth elements in improving the corrosion resistance of the material, achieving the purpose of low content and high corrosion resistance. In addition, the fine grain structure in the deformed magnesium material is more conducive to the CNC drilling tool cutting the material, reducing the micro-plastic deformation at the tip of the tool, and obtaining a high-gloss surface with better smoothness. In short, under the coupling effect between trace rare earth elements and refinement and modification elements, the material has less alloying element consumption, high plastic deformation efficiency, low production cost, and is suitable for mass production and application of electronic products (such as the housing of magnesium alloy housing or electronic devices).

[0085] In some embodiments, the magnesium alloy may include components with the following weight percentages: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum - cerium: 0.5% to 1.0%. Among them, lanthanum - cerium represents a lanthanum - cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% to 1.0%.

[0086] Exemplarily, the magnesium alloy may include the following components and their weight percentages: 4 wt.% Al, 1 wt.% Zn, 0.5 wt.% La / Ce, 0.4 wt.% Mn, 0.3 wt.% Ti, 0.2 wt.% Sb, and the balance is Mg and inevitable trace elements. The microstructural diagram of this magnesium alloy material can be referred to Figure 1 , such as Figure 1 shown. The gray area is Mg, and a uniform and fine second phase Mg - RE / Mg - Al - RE can be formed in Mg (as shown by arrow 10 in Figure 1 ). The presence of the second phase Mg - RE / Mg - Al - RE can reduce the potential difference with Mg, thereby reducing the corrosion tendency; at the same time, the second phase is uniformly distributed in Mg, improving the corrosion resistance of the magnesium alloy.

[0087] In some embodiments, based on the total weight of the magnesium alloy, the inevitable impurities in the magnesium alloy may include iron (Fe), copper (Cu), nickel (Ni), silicon (Si), etc., and the total amount of impurities (such as Fe, Cu, Ni, Si) in the magnesium alloy does not exceed 0.015%, wherein the content of iron (Fe) does not exceed 0.005%.

[0088] It should be understood that in order to improve the corrosion resistance of the magnesium alloy substrate, the content of impurities in the magnesium alloy substrate should not be too much, such as the total amount of impurities does not exceed 0.015%. Among them, the content of Fe element in the impurities has a greater impact on the corrosion resistance of the magnesium alloy. Therefore, the content of Fe element in the magnesium alloy should not be too high and should not exceed 0.005% of the total weight of the magnesium alloy.

[0089] In some embodiments, the composition of the magnesium alloy may further include tin (Sn), and the weight percentage of tin (Sn) is 0.1% to 1.0%.

[0090] It should be understood that by adding Sn element, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, so that the corrosion resistance of the prepared deformed magnesium material is further improved.

[0091] In some embodiments, the magnesium alloy may include components with the following weight percentages: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum-cerium: 0.5% to 1.0%, tin: 0.5% to 1.0%. Among them, lanthanum-cerium represents a lanthanum-cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% to 1.0%.

[0092] The following combines Table 1 to list the component compositions of the magnesium alloys of Examples 1 to 16, and combines Table 2 to list the component compositions of the magnesium alloys of Comparative Examples 1 to 7.

[0093] Table 1

[0094]

[0095] Table 2

[0096]

[0097]

[0098] Combining Table 1 and Table 2, it can be seen that the corrosion rates of the magnesium alloys of Examples 1 to 16 of this application after being immersed in a 3.5 wt% NaCl solution for 7 days are much lower than those of the commercial AZ31B (Comparative Example 8) and the magnesium alloys of Comparative Examples 1 to 7.

[0099] Meanwhile, it can be seen from Examples 1 to 3 and Comparative Example 1 that as the Al content increases, the corrosion rate of the magnesium alloy decreases (i.e., the better the corrosion resistance of the magnesium alloy), but the manufacturing cost of the magnesium alloy also increases accordingly; if the Al content is too low, the corrosion resistance of the magnesium alloy decreases, and the strength of the magnesium alloy decreases, making it unable to meet the mechanical reliability of the product. Therefore, through experiments, it is obtained in this application that when the Al content in the magnesium alloy is in the range of 2.5% to 4.5%, the corrosion resistance of the magnesium alloy can be improved while reducing the manufacturing cost. Combining Examples 4 and 5 and Comparative Example 2, it can be seen that when the Zn content in the magnesium alloy increases, the corrosion resistance decreases; when the Zn content in the magnesium alloy is too low, the strength of the magnesium alloy is relatively low, making it unable to meet the mechanical reliability of the product. Therefore, through experiments, it is obtained in this application that when the Zn content in the magnesium alloy is in the range of 0.5% to 1.0%, it is more appropriate. Mn in the magnesium alloy can play a role in removing impurities, such as neutralizing Fe in the impurities to avoid the decrease in corrosion resistance caused by Fe. However, when the Mn content is too high, it reacts with Al to form coarse Al-Mn phases, which is not conducive to improving the corrosion resistance of the magnesium alloy. Through experiments (such as Examples 6 and 7), it is obtained in this application that when the Mn content in the magnesium alloy is in the range of 0.2% to 0.8%, it is more suitable. The rare earth elements (La / Ce) added to the magnesium alloy can form a low-potential second phase, reduce the galvanic corrosion between the original Mg-Al phase and Mg, and improve the corrosion resistance of the magnesium alloy. However, the cost of the rare earth elements (La / Ce) is relatively high. Therefore, through experiments (such as Examples 12 and 13 and Comparative Example 5), it is obtained in this application that by controlling the total content of the lanthanum-cerium mixed elements in the magnesium alloy to be in the range of 0.5% to 1.5%, the corrosion resistance of the magnesium alloy can be improved while reducing the manufacturing cost. Adding Ti to the magnesium alloy can play a refining role, refining the α-Mg matrix and the second phase containing rare earth at the grain boundaries, ensuring the corrosion resistance of the material. However, when the Ti content is too low, the refining effect is not good; when the Ti content is too high, the corrosion resistance of the magnesium alloy will decrease. Therefore, through experiments (such as Examples 8 and 9 and Comparative Example 3), it is obtained in this application that by controlling the Ti content in the magnesium alloy to be in the range of 0.01% to 1.0%, while playing a refining role, it can also improve the corrosion resistance of the magnesium alloy. Adding Sb to the magnesium alloy can form a Mg-Sb phase at the grain boundaries, refine the second phase containing rare earth at the grain boundaries, and hinder the grain coarsening during hot deformation, ensuring the corrosion resistance of the material. However, when the Sb content is too low, the refining effect is not good; when the Sb content is too high, it will form a Sb-La / Ce phase, consuming La / Ce and thus reducing its effect, and reducing the corrosion resistance of the magnesium alloy. Therefore, through experiments (such as Examples 10 and 11 and Comparative Example 4), it is obtained in this application that by controlling the Sb content in the magnesium alloy to be in the range of 0.01% to 0.5%, while playing a refining role, it can also improve the corrosion resistance of the magnesium alloy.Adding Sn to the magnesium alloy can form high-melting-point phases in the material, which can hinder the grain coarsening during the hot extrusion process, making the grains of the deformed magnesium material fine and evenly distributed, and ensuring the corrosion resistance of the material. However, excessive Sn reacts with Mg to form large-sized Mg-Sn phases, which is not conducive to corrosion resistance. Therefore, through experiments (such as Examples 14 to 16 and Comparative Example 6), it is concluded in this application that controlling the content of Sn in the magnesium alloy within the range of 0.01% to 1.0% can not only play a refining role but also improve the corrosion resistance of the magnesium alloy.

[0100] It should be noted that the housing of the electronic device can be made of the above-mentioned magnesium alloy material formula in the embodiments of this application. Using a low-cost and corrosion-resistant magnesium alloy material can solve the corrosion-related problems of the product caused by the insufficient corrosion resistance of the base material in various environments such as salt spray and high temperature and high humidity. Matching with a transparent coating can achieve a high-gloss effect of the product while meeting the requirements of reliability tests.

[0101] Figure 2 and Figure 3 are schematic cross-sectional structural diagrams of two magnesium alloy housings provided by the embodiments of this application.

[0102] The magnesium alloy housing 100 includes a housing base material 110, a transition protection layer 120, a colored coating 130, and a transparent coating 140. Among them, the housing base material 110 is a corrosion-resistant magnesium alloy base material. That is to say, the housing base material 110 can be made of the above-mentioned magnesium alloy material formula. Based on the total weight of the magnesium alloy, the components and weight percentages of the corrosion-resistant magnesium alloy base material are: aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, and the rest are magnesium, additive elements, and inevitable impurities. The additive element is a lanthanum-cerium mixed element, and the total weight percentage of the lanthanum element and the cerium element is: 0.5% - 1.5%. Among them, the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.5.

[0103] The transition protection layer 120 is located on the surface of the housing base material 110. Exemplarily, the transition protection layer 120 can be a chemical conversion film and / or a micro-arc oxidation film.

[0104] The colored coating 130 is located on the side of the transition protection layer 120 away from the housing base material 110, and at least part of the transition protection layer 120 and the colored coating 130 do not cover the housing base material 110, so that part of the surface of the housing base material 110 is exposed without the coverage of the transition protection layer 120 and the colored coating 130, forming a local high-gloss area.

[0105] The transparent coating 140 is at least applied to the surface of the housing substrate 110 that is not covered by the transition protective layer 120 and the colored coating 130. That is to say, the exposed part of the housing substrate 110 is covered by the transparent coating 140, so that the local high-gloss effect of the magnesium alloy housing can be achieved, and the magnesium alloy housing has a strong metallic texture.

[0106] In addition, the transparent coating 140 can be formed at a preset position according to product requirements to improve the aesthetics of the magnesium alloy housing. Exemplarily, the transparent coating 140 can be located on the side of the magnesium alloy housing, at the corner position of the magnesium alloy housing (such as the side of the magnesium alloy housing), etc., and the present application does not limit this.

[0107] In addition, in order to improve the corrosion resistance of the magnesium alloy housing, the housing substrate can adopt a corrosion-resistant magnesium alloy substrate. By adding a small amount of low-cost mixed rare earth (La / Ce) and matching trace amounts of Ti and Sb elements in the alloy of the Mg-Al-Zn system with a low Al content, a large number of second phases with low corrosion potential and uniform distribution are generated in the material; on the one hand, the tendency of galvanic corrosion is reduced, and on the other hand, a uniform and continuous dense oxide film is quickly formed on the substrate during the corrosion process, hindering the further occurrence of corrosion, and the corrosion resistance of the material is greatly improved. At the same time, the presence of the Mg-Sb second phase in the material can effectively hinder the grain growth during the hot extrusion process of the ingot, so that the produced deformed magnesium material still has a fine-grained structure, fully exerting the beneficial effect of rare earth elements in improving the corrosion resistance of the material and achieving the purpose of low content and high corrosion resistance.

[0108] That is to say, the magnesium alloy housing provided by the embodiments of the present application solves the corrosion-related problems of products in various environments such as salt spray and high temperature and high humidity caused by insufficient corrosion resistance of the substrate by adopting a corrosion-resistant magnesium alloy substrate, and realizes the high-gloss effect of the product while meeting the reliability test requirements by matching with the transparent coating.

[0109] In some embodiments, as Figure 2 shown, the transition protective layer 120 has a first through groove, the colored coating 130 has a second through groove, and the projection of the second through groove on the housing substrate 110 along the first direction at least partially overlaps with the projection of the first through groove on the housing substrate 110 along the first direction, and the first direction is the thickness direction of the magnesium alloy housing. The transparent coating 140 can include a first part, and the first part of the transparent coating fills the first through groove and the second through groove and is attached to the surface of the housing substrate 110.

[0110] Exemplarily, the thickness of the first part of the transparent coating 140 in the first direction is the same as or approximately the same as the thicknesses of the transition protection layer 120 and the colored coating 110 in the first direction. That is to say, the surface of the first part of the transparent coating 140 away from the housing substrate 110 is substantially flush with the surface of the colored coating 120 away from the housing substrate 110 (the height difference is within a certain range).

[0111] It should be understood that, as Figure 2 shown, the transparent coating 140 of the magnesium alloy housing 100 can be obtained by an electrophoretic process.

[0112] In some embodiments, as Figure 3 shown, the transparent coating 140 may include a first part 141 and a second part 142 (that is, on the basis of Figure 2 the transparent coating 140 may further include a second part). The first part 141 of the transparent coating passes through the first through groove and the second through groove and adheres to the surface of the housing substrate 110; the second part 142 of the transparent coating covers the surface of the colored coating 130 away from the housing substrate 110.

[0113] It should be understood that, as Figure 3 shown, the transparent coating 140 of the magnesium alloy housing 200 can be obtained by a spraying process. When using the spraying process, the surface of the magnesium alloy housing 200 can be sprayed as a whole. Therefore, the transparent coating 140 can cover the entire surface of the colored coating 130 away from the housing substrate 110.

[0114] Exemplarily, for processing and production requirements and to achieve a better high-gloss effect, in the first direction, the thickness of the first part 141 of the transparent coating is less than or equal to 60 μm, and the thickness of the second part 142 of the transparent coating is less than or equal to 30 μm.

[0115] In a possible implementation manner, the housing substrate 110 includes a bent portion, the bent portion of the housing substrate 110 is not covered by the transition protection layer 120 and the colored coating 130, and the transparent coating 140 covers the bent portion of the housing substrate 110. This bent portion can be a chamfered part (such as a rounded corner or a beveled corner).

[0116] Exemplarily, the housing substrate 110 may include a first side surface and a second side surface, the first side surface and the second side surface intersect at a first side edge, the first side edge can be cut to form a first surface, that is to say, the first side surface and the second side surface intersect at the first surface, the first surface of the housing substrate 110 is exposed, and the transparent coating 140 can cover the intersecting surface of the first side surface and the second side surface (that is, the first surface). In this way, not only can a high-gloss effect be achieved on the surface of the housing substrate 110, but also a local high-gloss effect can be achieved on the side surface and the first surface of the housing substrate 110, thereby improving the aesthetics of the electronic product.

[0117] In a possible implementation, the composition of the magnesium alloy substrate may further include tin, and the weight percentage of the tin is 0.1% to 1.0%.

[0118] In the embodiment of the present application, by adding Sn element to the magnesium alloy substrate, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, so that the corrosion resistance of the prepared deformed magnesium material is further improved.

[0119] In a possible implementation, the magnesium alloy substrate includes the following components in weight percentages: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum-cerium: 0.5% to 1.0%. Among them, lanthanum-cerium represents a lanthanum-cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% to 1.0%.

[0120] In a possible implementation, the magnesium alloy substrate includes the following components in weight percentages: aluminum: 3% to 4%, zinc: 0.5% to 0.8%, manganese: 0.3% to 0.6%, titanium: 0.01% to 0.5%, antimony: 0.01% to 0.5%; lanthanum-cerium: 0.5% to 1.0%, tin: 0.5% to 1.0%. Among them, lanthanum-cerium represents a lanthanum-cerium mixed element, and the total weight percentage of lanthanum and cerium is 0.5% to 1.0%.

[0121] In a possible implementation, based on the total weight of the magnesium alloy substrate, the total amount of impurities such as iron, copper, nickel, and silicon does not exceed 0.015%, and among them, the content of iron does not exceed 0.005%.

[0122] It should be understood that in order to improve the corrosion resistance of the magnesium alloy substrate, the impurity content in the magnesium alloy substrate should not be too much, such as the total amount of impurities does not exceed 0.015%. Among them, the content of the Fe element in the impurities has a greater impact on the corrosion resistance of the magnesium alloy. Therefore, the content of the Fe element in the magnesium alloy should not be too high and should not exceed 0.005% of the total weight of the magnesium alloy.

[0123] The above combines Figure 2 and Figure 3 introduced the specific structure of the magnesium alloy housing. The following will combine Figure 4 and Figure 5 introduce the schematic flowcharts of two preparation methods of the magnesium alloy housing provided by the embodiments of the present application.

[0124] In some embodiments, as Figure 4 shown, the preparation method 300 of the magnesium alloy housing may include the following steps:

[0125] Step 301, batching

[0126] Weigh the raw materials according to the mass percentages of the components. Exemplarily, the corrosion-resistant magnesium alloy of Batch 1 includes the following components and their weight percentages: 4.5 wt.% Al, 0.7 wt.% Zn, 0.5 wt.% Mn, 0.7 wt.% La / Ce, 0.2 wt.% Ti, 0.4 wt.% Sb, and the rest is Mg and inevitable trace elements (i.e., impurities).

[0127] Optionally, in some other preparation methods, this step may further include: obtaining pure tin raw materials, and the weight percentage of tin may be 0.1% - 1.0%.

[0128] Step 302, alloy melting and casting

[0129] Melt pure magnesium, pure aluminum, and manganese chloride raw materials at 720°C. After stirring, degassing, and removing impurities, wait until the melt temperature stabilizes at 720°C, then add lanthanum-cerium alloy and pure antimony. Stir the melt after melting for 30 minutes; then raise the temperature of the melt to 800°C, add aluminum-titanium master alloy, keep warm for 30 minutes, then add refining agent, solvent, etc. to remove impurities for 60 minutes, and pour the melt into a mold to obtain a magnesium alloy ingot bar.

[0130] Optionally, in some other preparation methods, pure tin may be added simultaneously when adding pure antimony, so that the composition of the made magnesium alloy substrate further includes tin, and the weight percentage of tin is 0.1% - 1.0%. It should be understood that by adding Sn to the magnesium alloy substrate, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, so as to further improve the corrosion resistance of the prepared deformed magnesium material.

[0131] Step 303, homogenization treatment and hot extrusion

[0132] Process the magnesium alloy ingot bar into an ingot bar of a specified size, perform homogenization treatment at 350 - 400°C for 20 hours, and then prepare a sheet under the condition of an extrusion ratio of 30:1. Among them, this sheet is the above-mentioned housing substrate 110, and this housing substrate is a corrosion-resistant magnesium alloy substrate.

[0133] Step 304, computer numerical control (CNC) machining

[0134] The sheet is processed by a CNC machining center to obtain a housing with the required structural shape, and after grinding, chemical conversion or micro-arc oxidation, and spraying treatment, a blank is obtained.

[0135] For example, after the sheet material is processed by a CNC numerical control center to obtain a housing with the required structural shape, it can be polished as a whole to make the whole have better flatness. Then, a transition protective layer 120 can be formed on one side of the sheet material through a chemical conversion process and / or a micro-arc oxidation process. Subsequently, a colored coating 130 can be formed on the side of the transition protective layer away from the sheet material by a spraying process, thereby forming a material.

[0136] Step 305, drilling and cutting processing

[0137] Drill and cut the specified area on the surface of the material to remove the paint layer, micro-arc oxidation layer, and film layer in the specified area, exposing the corrosion-resistant magnesium alloy substrate with metallic luster to form a high-gloss area.

[0138] For example, drill and cut the specified area on the surface of the material, so as to form a first through groove on the transition protective layer 120 and a second through groove on the colored coating 130, and the projection of the second through groove on the housing substrate 110 along the first direction at least partially overlaps with the projection of the first through groove on the housing substrate 110 along the first direction. The first direction is the thickness direction of the magnesium alloy housing. It should be understood that the surface of the magnesium alloy substrate (i.e., the above-mentioned housing substrate 110) corresponding to the overlapping area of the first through groove and the second through groove in the first direction will be exposed, so that a high-gloss area with metallic luster can be formed.

[0139] Step 306, electrophoretic process processing

[0140] After the structural housing is cleaned and other processed, it is immersed in an electrophoretic tank. Under the condition of energization (such as the voltage is 120V and the time is 30s), the electrophoretic paint adheres to the high-gloss area obtained in step 305 to form a transparent coating 140. At least a part of the transparent coating 140 passes through the first through groove and the second through groove and adheres to the surface of the housing substrate. For example, the transparent coating 140 may include a first part, and the first part of the transparent coating fills the first through groove and the second through groove and adheres to the surface of the housing substrate 110.

[0141] Exemplarily, the thickness of the first part of the transparent coating 140 along the first direction is the same as or approximately the same as the thickness of the transition protective layer 120 and the colored coating 110 along the first direction. That is to say, the side of the first part of the transparent coating 140 away from the housing substrate 110 is substantially flush with the side of the colored coating 120 away from the housing substrate 110 (the height difference is within a certain range). Among them, the thickness of the first part of the transparent coating 140 is less than or equal to 60μm.

[0142] Step 307, baking treatment

[0143] Finally, a magnesium alloy product with a high-gloss effect (such as a magnesium alloy housing) is obtained through baking treatment. Among them, the baking temperature is 160 - 180°C and the time is 30min.

[0144] It should be understood that through steps 301 to 307, the magnesium alloy housing 100 as shown in Figure 2 can be obtained. That is to say, by using corrosion-resistant magnesium material and a one-time transparent coating process (such as electrophoresis process), the local high-gloss effect of the magnesium alloy housing 100 can be achieved, with a strong metallic texture. And the obtained magnesium alloy housing is subjected to a 120H salt spray test, without corrosion and blistering problems, the substrate has excellent corrosion resistance, and the corrosion rate is 0.181 ml / (cm 2 *d). It solves the problems of corrosion discoloration, paint peeling, blistering, etc. during the testing process of magnesium high-gloss products, and meets the product reliability requirements.

[0145] In addition, uniform and fine second-phase Mg-RE / Mg-Al-RE can be formed in the housing substrate, which can reduce the potential difference with the Mg matrix, thereby reducing the corrosion tendency; at the same time, the second phase is uniformly distributed in the matrix, improving the overall corrosion resistance. The corrosion-resistant magnesium alloy provided by this application has good corrosion resistance and high extrusion efficiency, and is suitable for mass production of large-size housings used in electronic products.

[0146] In some other embodiments, as shown in Figure 5 the preparation method 400 of the magnesium alloy housing may include the following steps:

[0147] Step 401, batching

[0148] Weigh the raw materials according to the mass percentage of the components. Exemplarily, the corrosion-resistant magnesium alloy of Batch 1 includes the following components and their weight percentages: 3.5 wt.% Al, 0.7 wt.% Zn, 0.5 wt.% Mn, 0.7 wt.% La / Ce, 0.2 wt.% Ti, 0.4 wt.% Sb, and the rest is Mg and unavoidable trace elements.

[0149] Optionally, in some other preparation methods, this step may further include: obtaining pure tin raw materials, and the weight percentage content of tin may be 0.1% to 1.0%.

[0150] Step 402, alloy melting and casting

[0151] Melt pure magnesium, pure aluminum, and manganese chloride raw materials at 720 °C. After stirring, degassing and impurity removal, wait for the melt temperature to stabilize at 720 °C, add lanthanum-cerium alloy, pure antimony, and pure tin, and stir the melt after melting for 30 min; then raise the temperature of the melt to 800 °C, add aluminum-titanium master alloy, keep warm for 30 min, then add refining agent, solvent, etc. to remove impurities for 60 min, and pour the melt into the mold to obtain a magnesium alloy ingot.

[0152] Optionally, in some other preparation methods, pure tin can be added simultaneously while adding pure antimony, so that the composition of the fabricated magnesium alloy substrate further includes tin, and the weight percentage of tin is 0.1% - 1.0%. It should be understood that by adding Sn to the magnesium alloy substrate, it can further play a role in refining the second phase, and at the same time hinder the grain coarsening during the hot deformation process of the ingot, further improving the corrosion resistance of the prepared deformed magnesium material.

[0153] Step 403, homogenization treatment and hot extrusion

[0154] The magnesium alloy ingot is processed into an ingot with a specified size, homogenized at 350 - 400 °C for 20 h, and then a sheet is prepared under an extrusion ratio of 30:1. Among them, this sheet is the above-mentioned housing substrate 110, and this housing substrate is a corrosion-resistant magnesium alloy substrate.

[0155] Step 404, CNC machining

[0156] The sheet is processed by a CNC numerical control center to obtain a housing with the required structural shape, and after grinding, chemical conversion or micro-arc oxidation, and spraying treatment, a blank is obtained.

[0157] For example, after the sheet is processed by a CNC numerical control center to obtain a housing with the required structural shape, it can be polished as a whole to make the whole have better flatness; then, a transition protection layer 120 can be formed on one side of the sheet through a chemical conversion process and / or a micro-arc oxidation process; subsequently, a colored coating 130 can be formed on the side of the transition protection layer away from the sheet by a spraying process, thereby forming a blank.

[0158] Step 405, drilling and cutting processing

[0159] Drilling and cutting are performed on a specified area on the surface of the blank to remove the paint layer, micro-arc oxidation layer, and film layer in the specified area, exposing the corrosion-resistant magnesium alloy substrate with a metallic luster to form a high-gloss area.

[0160] For example, drilling and cutting are performed on a specified area on the surface of the blank, so as to form a first through groove on the transition protection layer 120 and a second through groove on the colored coating 130, and the projection of the second through groove on the housing substrate 110 along a first direction at least partially overlaps with the projection of the first through groove on the housing substrate 110 along the first direction, and the first direction is the thickness direction of the magnesium alloy shell. It should be understood that the surface of the magnesium alloy substrate (i.e., the above-mentioned housing substrate 110) corresponding to the overlapping area of the first through groove and the second through groove in the first direction will be exposed, so that a high-gloss area with a metallic luster can be formed.

[0161] Step 406, spraying process processing

[0162] After the structural housing is processed such as cleaning, a transparent paint layer is sprayed by a spraying process to form a transparent coating 140. Among them, the transparent coating 140 may include a first part 141 and a second part 142. The first part 141 of the transparent coating passes through the first through groove and the second through groove and adheres to the surface of the housing substrate 110; the second part 142 of the transparent coating covers the side of the colored coating 130 away from the housing substrate 110.

[0163] When using the spraying process, it can be sprayed on the entire surface of the magnesium alloy housing 200. Therefore, the transparent coating 140 can cover the entire side of the colored coating 130 away from the housing substrate 110.

[0164] Exemplarily, for processing and production requirements and to achieve a better high-gloss effect, along the first direction, the thickness of the first part 141 of the transparent coating is less than or equal to 60 μm, and the thickness of the second part 142 of the transparent coating is less than or equal to 30 μm.

[0165] Step 407, baking treatment

[0166] Finally, through baking treatment, a magnesium alloy product (such as a magnesium alloy housing) with a high-gloss effect is obtained. Among them, the baking temperature is 80 - 100 °C and the time is 30 min.

[0167] It should be understood that through steps 401 to 407, a magnesium alloy housing 200 as shown in Figure 3 can be obtained. That is to say, by using a corrosion-resistant magnesium material and a one-time transparent coating process (such as a spraying process), the local high-gloss effect of the magnesium alloy housing 200 can be achieved, with a strong metallic texture. And the obtained magnesium alloy housing is subjected to a salt spray test for 120H, without corrosion and blistering problems, the substrate has excellent corrosion resistance, and the corrosion rate is 0.255 ml / (cm 2 *d). Solve the problems of corrosion discoloration, paint peeling, blistering, etc. during the testing process of magnesium high-gloss products, and meet the product reliability requirements.

[0168] In addition, uniform and fine second phases Mg-RE / Mg-Al-RE can be formed in the housing substrate, which can reduce the potential difference with the Mg matrix, thereby reducing the corrosion tendency; at the same time, the second phases are uniformly distributed in the matrix, improving the overall corrosion resistance. The corrosion-resistant magnesium alloy provided by this application has good corrosion resistance and high extrusion efficiency, and is suitable for mass production of large-sized housings used in electronic products.

[0169] In addition, the embodiment of this application also provides an electronic device, and the housing of this electronic device can adopt the structure as shown in Figure 2 or Figure 3 shown, or the housing of this electronic device can be made by using the above preparation method 300 or preparation method 400.

[0170] It should be understood that the electronic device may be a device with a housing, such as a mobile terminal including a mobile phone, a wearable device, a smart watch, a tablet computer, an e-reader, a notebook computer, a laptop computer, a mobile computer, an augmented reality device, a virtual reality device, a handheld game console, etc. The present application does not make any limitations thereto.

[0171] As described above, it is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all of them should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A magnesium alloy housing, characterized in that, Comprising: A housing base material, and the housing base material is a magnesium alloy base material; A transition protective layer, and the transition protective layer is located on the surface of the housing base material; A colored coating, and the colored coating is located on a side of the transition protective layer away from the housing base material, and at least part of the transition protective layer and the colored coating do not cover the housing base material; A transparent coating, and the transparent coating is at least adhered to a surface of the housing base material not covered by the transition protective layer and the colored coating; Wherein, the magnesium alloy base material comprises components with the following weight percentages: aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, and the balance is magnesium, additive elements and impurities; The additive elements include a lanthanum-cerium mixed element, and the total weight percentage of the lanthanum element and the cerium element is: 0.5% - 1.5%, wherein, the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.

5.

2. The magnesium alloy housing according to claim 1, characterized in that, The transition protective layer has a first through groove; the colored coating has a second through groove, and a projection of the second through groove on the housing base material along a first direction at least partially overlaps with a projection of the first through groove on the housing base material along the first direction, and the first direction is a thickness direction of the magnesium alloy housing; The transparent coating includes a first part, and the first part of the transparent coating fills the first through groove and the second through groove and is adhered to the surface of the housing base material.

3. The magnesium alloy housing according to claim 2, characterized in that Along the first direction, the thickness of the first part of the transparent coating is less than or equal to 60 μm.

4. The magnesium alloy housing according to claim 2 or 3, characterized in that, The transparent coating further includes a second part, and the second part of the transparent coating covers a side of the colored coating away from the housing base material.

5. The magnesium alloy housing according to claim 4, wherein Along the first direction, the thickness of the second part of the transparent coating is less than or equal to 30 μm.

6. The magnesium alloy housing according to any one of claims 1 to 5, characterized in that, The housing base material includes a bent portion, the bent portion of the housing base material is not covered by the transition protective layer and the colored coating, and the transparent coating covers the bent portion of the housing base material.

7. The magnesium alloy housing according to any one of claims 1 to 6, characterized in that, The additive elements further include tin, and the weight percentage of the tin is 0.1% - 1.0%.

8. The magnesium alloy housing according to any one of claims 1 to 6, characterized in that, The magnesium alloy base material comprises components with the following weight percentages: Aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum-cerium: 0.5% - 1.0%.

9. The magnesium alloy housing according to claim 7, wherein, The magnesium alloy base material comprises components with the following weight percentages: Aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum-cerium: 0.5% - 1.0%, tin: 0.5% - 1.0%.

10. The magnesium alloy housing according to any one of claims 1 to 9, characterized in that, Based on the total weight of the magnesium alloy base material, the total amount of iron, copper, nickel, and silicon in the impurities does not exceed 0.015%, wherein, the content of iron does not exceed 0.005%.

11. A magnesium alloy, characterized in that, The magnesium alloy comprises components with the following weight percentages: Aluminum: 2.5% - 4.5%, zinc: 0.5% - 1.0%, manganese: 0.2% - 0.8%, titanium: 0.01% - 1.0%, antimony: 0.01% - 0.5%, the balance being magnesium, additive elements and impurities; The additive elements include a lanthanum - cerium mixed element, and the total weight percentage content of the lanthanum element and the cerium element is 0.5% - 1.5%, wherein the weight ratio of the lanthanum element to the cerium element is 1.5 - 2.

5.

12. The magnesium alloy according to claim 11, wherein, The additive elements further include tin, and the weight percentage content of the tin is 0.1% - 1.0%.

13. The magnesium alloy according to claim 11, characterized in that, The magnesium alloy comprises the following components by weight percentage: Aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%.

14. The magnesium alloy according to claim 12, characterized in that, The magnesium alloy comprises the following components by weight percentage: Aluminum: 3% - 4%, zinc: 0.5% - 0.8%, manganese: 0.3% - 0.6%, titanium: 0.01% - 0.5%, antimony: 0.01% - 0.5%; lanthanum - cerium: 0.5% - 1.0%, tin: 0.5% - 1.0%.

15. The magnesium alloy according to any one of claims 11 to 14, characterized in that, Based on the total weight of the magnesium alloy, the total amount of iron, copper, nickel, and silicon in the impurities does not exceed 0.015%, wherein the content of the iron does not exceed 0.005%.

16. An electronic device, characterized in that, Comprising the magnesium alloy housing according to any one of claims 1 to 10.

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