A semi-solid die-casting Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy and a preparation process thereof

Abstract

This invention discloses a semi-solid die-cast Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy and its preparation process. The Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy comprises the following components by mass percentage: Al: 4-9%, Zn: 2-6%, Sn: 0.1-2%, Mn: 0.1-1%, Ca: 0.1-0.8%, unavoidable impurity elements <0.05%, and the remainder being Mg; wherein the mass ratio of Al to Zn is (0.6-2):1. This invention achieves morphological control and distribution optimization of the second phase in the alloy microstructure by controlling the Al / Zn ratio and synergistic modification of Sn, Mn, and Ca elements, and by matching and optimizing the process temperature range of semi-solid die casting. This transforms the brittle second phase, which is continuously distributed in a network at grain boundaries, into a dispersed blocky second phase, thus achieving synergistic optimization of high strength and high plasticity of the magnesium alloy.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloys and their processing technology, specifically to a semi-solid die-cast Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy and its preparation process. Background Technology

[0002] Die casting is currently the main manufacturing process for magnesium alloy structural components. However, traditional liquid die casting is prone to defects such as porosity, shrinkage cavities, and coarse dendrites, resulting in insufficient material plasticity and service reliability, which limits its application in high-performance load-bearing structural components. Semi-solid metal forming technology can complete the forming process in the solid-liquid two-phase region of the metal, and has the advantages of stable mold filling, fewer casting defects, and the ability to obtain fine spheroidal crystal structures. It is an important development direction for high-performance precision forming of magnesium alloys.

[0003] The AZ series Mg-Al-Zn magnesium alloys, which are currently the most widely used in industry, are all designed for traditional liquid die casting processes and have extremely poor compatibility with semi-solid die casting processes. The core defect is that β-Mg tends to form a continuous network distribution at the grain boundaries. 17 Al 12 The brittle phase has poor thermal stability, resulting in insufficient room temperature plasticity and high temperature strength of the alloy.

[0004] Existing technologies often modify Mg-Al-Zn alloys by adding elements such as Sn, Mn, and Ca. While this can optimize individual alloy properties to some extent, the rheological properties and microstructure stability remain insufficient under semi-solid die-casting conditions, making it difficult to meet the manufacturing requirements of high-performance semi-solid die-cast structural parts. Therefore, there is an urgent need to develop a magnesium alloy system that can form a stable spheroidal crystal structure under semi-solid die-casting conditions and further improve the mechanical and formability properties of magnesium alloys. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of continuous distribution of brittle phases at grain boundaries and the difficulty in balancing strength and plasticity in the semi-solid die casting process of magnesium alloys in the prior art. This invention provides a semi-solid die casting Mg-Al-Zn-Sn-Mn-Ca multi-component magnesium alloy and its preparation process. By controlling the content and mass ratio of Al and Zn elements, synergistically introducing Sn, Mn, and Ca elements for modification, and matching and optimizing the process temperature range of semi-solid die casting, the morphology and distribution of the second phase in the alloy microstructure are controlled and optimized. This transforms the continuous network distribution of brittle second phase at grain boundaries into a dispersed blocky second phase, thereby significantly improving the overall mechanical properties of the alloy. This Mg-Al-Zn-Sn-Mn-Ca multi-component magnesium alloy is suitable for semi-solid die casting or thixotropic molding processes. After forming, it can obtain a microstructure with fine α-Mg grains and a dispersed second phase, thus achieving synergistic optimization of high strength and high plasticity in magnesium alloys.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] The first aspect of this invention provides a Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy, wherein the Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy is prepared by a semi-solid die casting process, and the Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy comprises the following components by mass percentage:

[0008] Al: 4-9%, Zn: 2-6%, Sn: 0.1-2%, Mn: 0.1-1%, Ca: 0.1-0.8%, unavoidable impurity elements <0.05%, the remainder is Mg; wherein, the mass ratio of Al to Zn is (0.6-2):1.

[0009] During the semi-solid heating and holding process, the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy of the present invention can form a fine-grained α-Mg matrix and a dispersed β-Mg matrix. 17 Al 12 The second-phase structure, the roles of each element, and the synergistic regulation mechanism are as follows: Al element forms Mg in the matrix. 17 Al 12 The mass fraction of this phase is controlled at 2-6%, mainly distributed at grain boundaries. Zn element is dissolved in the α-Mg matrix and participates in the formation of Mg-Zn-Sn intermetallic compounds. By controlling the mass ratio of Al to Zn element within the range of (0.6-2):1, the synergistic regulation of the second phase structure can be achieved. Sn element precipitates in the form of Mg2Sn phase and is dispersed in the grain and at grain boundaries. Trace amounts of Ca element can combine with Sn element to form a high-melting-point CaMgSn phase, effectively pinning grain boundaries and inhibiting grain coarsening. Mn element can form Al-Mn phase or Al6(Fe,Mn) phase with trace amounts of Fe and Al elements in the melt, achieving melt purification and refining grains.

[0010] Under the synergistic effect of the above elements, the β-Mg in the multi-element magnesium alloy, which was originally distributed in a continuous network, becomes more stable. 17 Al 12 The transformation of the brittle phase into a discontinuous, blocky structure, combined with the dispersed distribution of Mg2Sn and CaMgSn phases, can stably control the grain size of the alloy within the range of 5-10 μm, significantly improving the toughness and high-temperature strength of the alloy.

[0011] Furthermore, the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy has a wide solid-liquid two-phase range, with a solidus temperature (i.e., solid phase initiation temperature) of 325-345 ℃, a liquidus temperature (i.e., complete melting temperature) of 590-610 ℃, and a semi-solid temperature window greater than 260 ℃.

[0012] Furthermore, the semi-solid forming temperature of the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy is 380-580℃, and the solid fraction is 40-60%.

[0013] A second aspect of this invention provides a preparation process for the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy described in the first aspect, comprising the following steps:

[0014] (1) Weigh the corresponding raw materials according to the composition ratio of the target Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy, place the raw materials in the melting equipment and melt them at 680-720 °C. After the raw materials are completely melted, refine and remove impurities, and then cast the magnesium alloy ingot.

[0015] (2) The magnesium alloy ingot obtained in step (1) is subjected to homogenization heat preservation treatment at 460-500 ℃, and then air-cooled after the heat preservation is completed;

[0016] (3) The magnesium alloy ingot after homogenization and heat preservation treatment in step (2) is processed into semi-solid die casting billet particles, which are then sent to a semi-solid die casting machine and heated to 380-580 ℃. During the heating process, the solid phase of the slurry is controlled to be 40-60%, and a semi-solid slurry is obtained by stirring.

[0017] (4) Inject the semi-solid slurry obtained in step (3) into the cavity of the semi-solid die casting mold, and apply pressure holding treatment after injection filling is completed;

[0018] (5) After the pressure holding is completed, the die casting mold and casting are cooled. After the casting is cooled, the mold is opened and the casting is demolded to obtain the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy.

[0019] The preparation process provided by this invention consists of conventional magnesium alloy processing steps, making it highly feasible and reproducible. During the preparation of the semi-solid slurry, micro-thermometry or differential scanning calorimetry (DSC) can be used to precisely detect and control the solid-liquid ratio of the slurry, and the holding time can be adjusted to ensure that the matrix grain size and second phase distribution meet the desired targets.

[0020] Further, in step (1), the raw materials include pure Mg ingots, pure Al ingots, pure Zn granules, pure Sn ingots, and magnesium-based master alloys corresponding to Mn and Ca elements; the purity of all raw materials is not less than 99.9%.

[0021] Furthermore, in step (2), the homogenization and heat preservation treatment time is 40-56 h. The heat preservation process allows the alloying elements to be fully dissolved in the matrix, eliminating the segregation of the ingot composition.

[0022] Furthermore, in step (4), the die-casting mold is preheated to 200-300 ℃.

[0023] Furthermore, in step (4), the die-casting mold is a semi-solid die-casting mold or a semi-solid thixotropic injection molding mold.

[0024] Furthermore, in step (5), the cooling process cools the mold and casting at a cooling rate of not less than 20 °C / s.

[0025] In a specific embodiment, the preparation process of Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy includes the following steps:

[0026] (1) Weigh the corresponding raw materials according to the composition ratio of the target Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy, place the raw materials in an induction furnace and melt them at 680-720 °C. After the raw materials are completely melted, refine and remove impurities, and then cast them to obtain magnesium alloy ingots.

[0027] (2) The magnesium alloy ingot obtained in step (1) is subjected to homogenization heat treatment at 460-500 ℃ for 40-56 h to allow the alloying elements to be fully dissolved in the matrix and to eliminate compositional segregation. After the heat treatment is completed, it is air-cooled.

[0028] (3) The magnesium alloy ingot after homogenization and heat preservation treatment in step (2) is processed into semi-solid die casting billet particles, which are then sent to a semi-solid die casting machine and heated to 380-580 ℃. During the heating process, the solid phase of the slurry is controlled to be 40-60%, and mechanical stirring is carried out at the same time to make the grains spheroidized to form a semi-solid slurry with good fluidity.

[0029] (4) Inject the semi-solid slurry obtained in step (3) into the cavity of the semi-solid die casting mold preheated to 200-300 ℃, inject at high speed and maintain appropriate pressure. The injection speed should ensure that the slurry is poured evenly so that the alloy fills all cavities.

[0030] (5) After the pressure holding is completed, the die casting mold and casting are cooled at a cooling rate of not less than 20 ℃ / s. After the casting is cooled to room temperature, the mold is opened and the casting is demolded to obtain the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy.

[0031] The above-described technical solution of the present invention has the following beneficial effects:

[0032] 1. The semi-solid die-cast Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy provided by this invention achieves control over the morphology and distribution of the second phase of the alloy through the regulation of the Al / Zn ratio and the synergistic modification of Sn, Mn and Ca elements. This transforms the continuous network distribution of β-Mg in traditional magnesium alloys into a more robust and sustainable system. 17 Al12 The brittle phase transforms into a discontinuous, blocky structure, which, combined with the dispersed distribution of spheroidized Mg2Sn and CaMgSn phases, effectively prevents crack propagation.

[0033] 2. The Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy provided by this invention has a semi-solid processing temperature window of not less than 260 ℃. During the semi-solid forming process, a uniform and fine spherical α-Mg matrix structure can be stably obtained. The slurry has excellent rheological properties and strong forming stability. It is suitable for industrial forming processes such as semi-solid die casting and thixotropic molding, and solves the technical problem of poor compatibility between traditional AZ series magnesium alloys and semi-solid die casting processes.

[0034] 3. The semi-solid die-cast Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy provided by this invention does not contain rare earth elements. All alloying elements used are conventional industrial raw materials, with moderate cost and strong compatibility of preparation process. The resulting products have excellent corrosion resistance and recyclability, and can be widely used in lightweight heat dissipation structural components in new energy vehicles, 3C electronics and other fields.

[0035] 4. This invention achieves synergistic optimization of high strength and high plasticity of magnesium alloys. The resulting semi-solid die-cast Mg-Al-Zn-Sn-Mn-Ca multi-element magnesium alloy has a tensile strength of up to 300 MPa, a yield strength of up to 170 MPa, and an elongation of up to 12%. Its comprehensive performance is significantly better than that of the traditional AZ91D magnesium alloy (tensile strength of about 240 MPa and elongation of about 2-6%). Detailed Implementation

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0039] Example 1

[0040] A Mg-6Al-4Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 6%, Zn: 4%, Sn: 1%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg; wherein the mass ratio of Al to Zn is 1.5:1.

[0041] The preparation process of the Mg-6Al-4Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Example 1 includes the following steps:

[0042] (1) Weigh the corresponding raw materials according to the composition ratio of the target Mg-6Al-4Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy, place the raw materials in an induction furnace and melt them at 700 °C. After the raw materials are completely melted, refine and remove impurities, and then cast the magnesium alloy ingot.

[0043] (2) The magnesium alloy ingot obtained in step (1) is subjected to homogenization heat treatment at 480 °C for 48 h to allow the alloying elements to be fully dissolved in the matrix and to eliminate compositional segregation. After the heat treatment is completed, it is air-cooled.

[0044] (3) The magnesium alloy ingot after homogenization and heat preservation treatment in step (2) is processed into metal sheets and sent into a semi-solid die casting machine to be heated to 470 ℃ (below the liquidus temperature of the alloy). During the heating process, the solid phase of the slurry is controlled to be 50%. Mechanical stirring is carried out in the semi-solid die casting machine to make the grains spheroidized to form a semi-solid slurry with good fluidity, low viscosity and stability.

[0045] (4) The semi-solid slurry obtained in step (3) is sent into the injection chamber of the semi-solid die casting machine. After the mold is closed and the mold closing pressure reaches 2100 kN, the punch injects the semi-solid slurry into the cavity of the semi-solid die casting mold that is preheated to 275 ℃ and coated with release agent at an injection speed of 3 m / s. The injection speed should ensure that the slurry is poured evenly. After the filling is completed, pressure holding treatment is applied immediately. During the pressure holding process, the slurry is ensured to completely fill all cavities of the mold.

[0046] (5) After the pressure holding is completed, the mold and casting are cooled at a cooling rate of not less than 20 °C / s. After the casting is cooled to room temperature, the mold is opened and the casting is demolded to obtain the Mg-6Al-4Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy.

[0047] Example 2

[0048] A Mg-5Al-5Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 5%, Zn: 5%, Sn: 1%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg;

[0049] The preparation process of the Mg-5Al-5Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Example 2 is basically the same as that in Example 1.

[0050] Example 3

[0051] A Mg-4Al-6Zn-0.5Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 4%, Zn: 6%, Sn: 0.5%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg;

[0052] The preparation process of the Mg-4Al-6Zn-0.5Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Example 3 is basically the same as that in Example 1.

[0053] Comparative Example 1

[0054] A Mg-7Al-3Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 7%, Zn: 3%, Sn: 1%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg;

[0055] The preparation process of the Mg-7Al-3Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Comparative Example 1 is basically the same as that in Example 1.

[0056] Comparative Example 2

[0057] A Mg-1Al-9Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 1%, Zn: 9%, Sn: 1%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg;

[0058] The preparation process of the Mg-1Al-9Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Comparative Example 2 is basically the same as that in Example 1.

[0059] Comparative Example 3

[0060] A Mg-4Al-6Zn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 4%, Zn: 6%, Mn: 0.3%, Ca: 0.2%, unavoidable impurity elements <0.05%, and the remainder being Mg;

[0061] The high-pressure die-casting preparation process of the Mg-4Al-6Zn-0.3Mn-0.2Ca series multi-element magnesium alloy of Comparative Example 3 includes the following steps:

[0062] (1) Weigh the corresponding raw materials according to the composition ratio of the target Mg-4Al-6Zn-0.3Mn-0.2Ca series multi-element magnesium alloy, place the raw materials in an induction furnace and melt them at 700 °C. After the raw materials are completely melted, refine and remove impurities.

[0063] (2) The magnesium alloy melt obtained in step (1) is poured into a cold chamber high-pressure die casting machine with a mold temperature of 200 ℃ to prepare a specific casting. The ingot is subjected to homogenization heat treatment at 480 ℃ for 48 h to allow the alloying elements to be fully dissolved in the matrix and to eliminate compositional segregation. After the heat treatment is completed, it is air-cooled.

[0064] (3) Inject the magnesium alloy melt from step (2) into the mold, inject at high speed and maintain appropriate pressure. The injection speed should ensure that the slurry is poured evenly so that the alloy fills all the cavities.

[0065] (4) After the pressure holding is completed, the mold and casting are cooled at a cooling rate of not less than 20 °C / s. After the casting is cooled to room temperature, the mold is opened and the casting is demolded to obtain the Mg-Al-Zn-Mn-Ca series multi-element magnesium alloy.

[0066] Comparative Example 4

[0067] A Mg-4Al-6Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 4%, Zn: 6%, Mn: 0.3%, Ca: 0.2%, with the remainder being Mg and unavoidable impurity elements <0.05%;

[0068] The preparation process of the Mg-4Al-6Zn-1Sn-0.3Mn-0.2Ca series multi-element magnesium alloy in Comparative Example 4 is basically the same as that in Comparative Example 3.

[0069] Test Example 1

[0070] The magnesium alloys of Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, and the test methods are as follows:

[0071] Magnesium alloy specimens were machined into tensile specimens with a cross-sectional dimension of 6 mm × 2 mm and a gauge length of 25 mm. Room temperature tensile properties were tested using an electronic universal testing machine at a strain rate of 1.0 × 10⁻⁶. -3 s -1 Before testing, the sample surface was polished with sandpaper to remove scratches. During loading, an electronic extensometer was used to collect strain data of the sample in real time, and the stress was automatically calculated by the testing machine based on the loading force and the original cross-sectional area of ​​the sample. To ensure the reliability and repeatability of the test results, each group of samples was tested in parallel three times, and the arithmetic mean was taken as the final test result.

[0072] The test results are shown in Table 1:

[0073]

[0074] As shown in Table 1, the magnesium alloys of Examples 1-3 of this invention all achieved synergistic optimization of high strength and high plasticity, with significantly better overall performance than the magnesium alloys of the comparative examples. Among them, the magnesium alloy of Example 1 falls within the preferred formulation range of this invention, exhibiting optimal synergistic effects of each element, combining balanced strength and plasticity, and demonstrating the best overall performance. The increased Zn content in the magnesium alloy of Example 2 further optimized the alloy's plasticity; although the yield strength decreased slightly, the elongation after fracture significantly increased, exhibiting superior formability. Although the Sn content in the magnesium alloy of Example 3 was relatively low, the higher Zn content further optimized the alloy's plastic deformation capability. The magnesium alloy of Comparative Example 1 had a high Al content, which, while increasing the yield strength, significantly increased β-Mg content due to excessive Al. 17 Al 12 The brittle phase severely fractures the matrix during stretching, resulting in a significant decrease in both tensile strength and elongation. While the magnesium alloy in Comparative Example 2 exhibits enhanced plasticity, its yield strength is significantly reduced, failing to achieve a balance between strength and plasticity. The magnesium alloys in Comparative Examples 3 and 4, produced using high-pressure die casting, show lower tensile strength, yield strength, and elongation compared to the semi-solid die-cast magnesium alloys. Semi-solid die casting, through laminar flow filling and spheroidal grain structure, significantly reduces defects, resulting in a substantial improvement in both strength and plasticity of the magnesium alloy.

[0075] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy, characterized in that, The Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy is produced by a semi-solid die casting process, and the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy comprises the following components by mass percentage: Al: 4-9%, Zn: 2-6%, Sn: 0.1-2%, Mn: 0.1-1%, Ca: 0.1-0.8%, unavoidable impurity elements <0.05%, the remainder is Mg; wherein, the mass ratio of Al to Zn is (0.6-2):

1.

2. The Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy according to claim 1, characterized in that, The solidus temperature of the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy is 325-345 ℃, the liquidus temperature is 590-610 ℃, and the semi-solid temperature window is greater than 260 ℃.

3. The Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy according to claim 1, characterized in that, The semi-solid forming temperature of the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy is 380-580 ℃, and the solid fraction is 40-60%.

4. A preparation process for a Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Weigh the corresponding raw materials according to the composition ratio of the target Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy, place the raw materials in the melting equipment and melt them at 680-720 °C. After the raw materials are completely melted, refine and remove impurities, and then cast the magnesium alloy ingot. (2) The magnesium alloy ingot obtained in step (1) is subjected to homogenization heat preservation treatment at 460-500 ℃, and then air-cooled after the heat preservation is completed; (3) The magnesium alloy ingot after homogenization and heat preservation treatment in step (2) is processed into semi-solid die casting billet particles, which are then sent to a semi-solid die casting machine and heated to 380-580 ℃. During the heating process, the solid phase of the slurry is controlled to be 40-60%, and a semi-solid slurry is obtained by stirring. (4) Inject the semi-solid slurry obtained in step (3) into the cavity of the semi-solid die casting mold, and apply pressure holding treatment after injection filling is completed; (5) After the pressure holding is completed, the die casting mold and casting are cooled. After the casting is cooled, the mold is opened and the casting is demolded to obtain the Mg-Al-Zn-Sn-Mn-Ca series multi-element magnesium alloy.

5. The preparation process according to claim 4, characterized in that, In step (1), the raw materials include pure Mg ingots, pure Al ingots, pure Zn granules, pure Sn ingots, and magnesium-based master alloys corresponding to Mn and Ca elements.

6. The preparation process according to claim 4, characterized in that, In step (1), the purity of all raw materials is not less than 99.9%.

7. The preparation process according to claim 4, characterized in that, In step (2), the homogenization and heat preservation treatment takes 40-56 hours.

8. The preparation process according to claim 4, characterized in that, In step (4), the die-casting mold is preheated to 200-300 ℃.

9. The preparation process according to claim 4, characterized in that, In step (4), the die casting mold is a semi-solid die casting mold or a semi-solid thixotropic injection molding mold.

10. The preparation process according to claim 4, characterized in that, In step (5), the cooling process cools the mold and casting at a cooling rate of not less than 20°C / s.

Images