High-strength and high-plasticity magnesium alloy based on rotary swaging and flash annealing and preparation method of high-strength and high-plasticity magnesium alloy

Abstract

The invention discloses a high-strength and high-plasticity magnesium alloy based on rotary swaging and flash annealing and a preparation method of the high-strength and high-plasticity magnesium alloy, and relates to the technical field of magnesium alloy materials. The high-strength and high-plasticity magnesium alloy is obtained through multiple times of rotary swaging treatment, flash annealing treatment and water quenching, and phases, corresponding to the process temperature intervals of the homogenizing heat treatment and the hot extrusion treatment, of element components of the high-strength and high-plasticity magnesium alloy only comprise an Mg phase and an Al2Ca phase. According to the high-strength and high-plasticity magnesium alloy based on rotary swaging and flash annealing and the preparation method of the high-strength and high-plasticity magnesium alloy, the strength and plasticity of the magnesium alloy can be improved at the same time.

Description

Technical Field

[0001] The present application relates to the technical field of magnesium alloy materials, and in particular to a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing and a preparation method thereof. Background Art

[0002] The density of magnesium alloy is only 1.8g / cm 3 , has excellent lightweight prospects, but its absolute strength and plasticity are low, which seriously hinders its application. Therefore, it is urgent to improve the strength and plasticity of magnesium alloys to break the limitations of their application.

[0003] Some traditional methods improve material strength by introducing defects, but at the same time they also damage its ductility, while ordinary heat treatment can reduce defects, but usually reduces strength. Therefore, it is difficult to balance the strength and plasticity of magnesium alloys. At present, there are also some research results that improve the strength and plasticity of magnesium alloys by introducing rare earth elements, but the cost is very high. Summary of the invention

[0004] The purpose of the present application is to provide a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing and a preparation method thereof, which can simultaneously improve the strength and plasticity of the magnesium alloy.

[0005] The inventors of this application found in the research process that the fundamental reason for the low strength and low plasticity of magnesium metal is that its base surface Dislocations are very easy to start, but non-basal slips are difficult to start.<c+a> Dislocations can be coordinated <c>Axial strain is an important carrier of plastic deformation in magnesium and magnesium alloys.<c+a> The critical shear stress of dislocation opening is much higher than that of basal plane.< / c> Dislocations are difficult to open in magnesium alloys, which is one of the reasons why magnesium and magnesium alloys have poor plasticity.<c+a> The opening of dislocations, although this can improve the plasticity of magnesium alloys, most alloying methods require the introduction of rare earth elements, which is very costly.

[0006] To achieve the above-mentioned purpose, the present application provides a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, which is obtained by sequentially subjecting the raw materials to smelting and mixing, casting, homogenization heat treatment, hot extrusion treatment, and multiple rotary forging treatments, flash annealing treatments, and water quenching, and the elemental composition of the high-strength and high-plasticity magnesium alloy in the process temperature range of the homogenization heat treatment and the hot extrusion treatment only includes Mg phase and Al2Ca phase. The present application designs the elemental composition of the magnesium alloy to obtain a phase that is conducive to promoting<c+a> The Mg-Al-Ca ternary alloy system formed by dislocations and the rotary forging process was used to introduce a large amount of Dislocations and<c+a> dislocation, and then use flash annealing to Dislocation climb recovery, while retaining part<c+a> dislocations, these retained<c+a> Dislocations can continue to move during subsequent tensile deformation, solving the problem of<c+a> The problem of dislocation difficulty in starting is solved, thereby improving the strength and plasticity of the alloy. In addition, flash annealing causes Al-Ca nanophase to precipitate in the alloy, further improving the strength of the alloy.

[0007] In some embodiments of the present application, the smelting and mixing is carried out under the condition of protective gas, and the smelting temperature is 680°C to 720°C; and / or, the temperature of the homogenization heat treatment is 350°C to 450°C, and the time is 12 hours to 24 hours; and / or, when performing the hot extrusion treatment, preheating is performed for 10 minutes to 20 minutes, and then extrusion is performed at 250°C to 350°C; and / or, the total equivalent effect variable of the multi-pass rotary forging treatment is 10% to 20%; and / or, the flash annealing treatment adopts induction heating, and the heating temperature is 400°C to 450°C, and the heating time is 5 seconds to 20 seconds.

[0008] In some embodiments of the present application, the high-strength and high-plasticity magnesium alloy is composed of the following elemental components in the following mass percentages: 5% to 6% aluminum, 0.7% to 0.8% calcium, and the remainder being magnesium and unavoidable impurities ≤ 0.05%.

[0009] The present application also provides a preparation method of a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, comprising: determining the raw material composition according to the designed elemental composition, and weighing the corresponding raw materials for use, wherein the phases corresponding to the elemental composition in the process temperature range of homogenization heat treatment and hot extrusion treatment only include Mg phase and Al2Ca phase; heating the raw materials to melt under the condition of protective gas, and casting the raw materials after they are smelted and mixed into molten metal; sequentially subjecting the obtained alloy ingot to the homogenization heat treatment and the hot extrusion treatment; subjecting the alloy obtained by the hot extrusion treatment to multi-pass rotary forging treatment; and subjecting the alloy obtained by the rotary forging treatment to flash annealing and water quenching to obtain the high-strength and high-plasticity magnesium alloy.

[0010] In some embodiments of the present application, the total equivalent effect variable of the multi-pass rotary forging process is 10% to 20%.

[0011] In some embodiments of the present application, the flash annealing treatment adopts induction heating, and the heating temperature is 400° C. to 450° C., and the heating time is 5 seconds to 20 seconds.

[0012] In some embodiments of the present application, the design method of the elemental composition of the high-strength and high-plasticity magnesium alloy includes: calculating the phase composition of the magnesium-aluminum-calcium ternary alloy at different temperatures through a thermodynamic ternary phase diagram, and selecting the elemental composition that only includes the Mg phase and the Al2Ca phase in the range of 350°C to 450°C.

[0013] In some embodiments of the present application, the raw material components, measured in mass percentage, include: 5% to 6% pure aluminum, 2.3% to 2.7% magnesium-30wt.% calcium master alloy, and the rest is pure magnesium.

[0014] In some embodiments of the present application, the temperature of the homogenization heat treatment is 350°C to 450°C, and the time is 12 hours to 24 hours; and / or, when performing the hot extrusion treatment, the alloy is first preheated for 10 minutes to 20 minutes, and then extruded at 250°C to 350°C.

[0015] In some embodiments of the present application, the protective gas is a mixed gas of CO2 and SF6 or a mixed gas of argon and SF6; the heating temperature of the raw material is 680°C to 720°C.

[0016] Compared with the prior art, the high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing and the preparation method thereof of the present application have the following beneficial effects:

[0017] The present invention designs the element composition so that the phases corresponding to the process temperature range of homogenization heat treatment and hot extrusion treatment only include Mg phase and Al2Ca phase, so that there is only Al2Ca second phase in the extruded alloy. The Mg-Al-Ca alloy designed in this way is easier to suppress twinning during rotary forging and promote<c+a> Dislocations are formed to coordinate plastic deformation, so it has good plasticity, so that it will not crack due to poor plasticity during the rotary forging process.

[0018] At the same time, the present invention introduces a multi-pass rotary forging process and a flash annealing process, so that the alloy can accumulate a large amount of<c+a> Dislocations can be retained after annealing, which can continue to slide and coordinate plasticity on the one hand, and improve the strength of the alloy by strengthening dislocations on the other hand. Furthermore, there are a large number of lattice defects in the alloy after rotary forging, which can increase the atomic diffusion rate, thereby accelerating the formation of Al-Ca precipitation phase during annealing and further improving the strength of the alloy.

[0019] In summary, the high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing and the preparation method thereof of the present application can simultaneously improve the strength and plasticity of the magnesium alloy, and the tensile strength can be as high as 363 MPa and the elongation can be as high as 27.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals represent similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only used for the purpose of illustration and description, and are not intended to limit the scope of this application. Other embodiments may also accomplish the inventive intent in this application. It should be understood that the drawings are not drawn to scale. Among them:

[0021] Figure 1 This is a transmission electron microscope image of the high-strength and high-plasticity magnesium alloy of Example 1 of the present application;

[0022] Figure 2 This is a transmission electron microscope image of the magnesium alloy of Comparative Example 2 of the present application;

[0023] Figure 3 The backscattered electron diffraction diagram and scanning electron microscope diagram of the high-strength and high-plasticity magnesium alloy of Example 1 of the present application and the schematic diagram of the starting ratio of each slip system under 4% strain of Example 1, Comparative Example 1 and Comparative Example 3;

[0024] Figure 4 This is a tensile performance test diagram of Example 1 and Comparative Example 3 of the present application;

[0025] Figure 5 This is a tensile performance test diagram of Comparative Example 1 and Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0026] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content in the present application. It will be apparent to those skilled in the art that various local modifications to the disclosed embodiments are apparent, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0027] The present application provides a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, wherein the magnesium alloy is obtained by sequentially subjecting raw materials to smelting and mixing, casting, homogenizing heat treatment, hot extrusion treatment, and multiple rotary forging treatments, flash annealing treatments, and water quenching, and the elemental components of the magnesium alloy correspond to phases only including Mg phase and Al2Ca phase in the process temperature range of the homogenizing heat treatment and the hot extrusion treatment, so that the alloy obtained after the homogenizing heat treatment and the hot extrusion treatment has only Al2Ca second phase.

[0028] This microstructured alloy is more likely to suppress twinning during subsequent rotary forging, promoting<c+a> Dislocation formation coordinates plastic deformation so that it will not crack due to poor plasticity during rotary forging. Therefore, after multiple rotary forging processes, a large amount of<c+a> Dislocation, after a very short flash annealing, can quickly eliminate defects.<c+a> The high climb barrier of dislocations and the limited annihilation time allow them to be retained. During the swaging and flash annealing process, nano-scale Al-Ca precipitates (Al2Ca) and clusters are formed, becoming<c+a> The barrier to dislocation climb further helps retain<c+a> These retained<c+a> On the one hand, dislocations can slide during subsequent deformation, thereby significantly improving ductility; on the other hand, they can increase the strength of the alloy by forest dislocation strengthening.

[0029] At the same time, due to the presence of a large number of lattice defects in the alloy after rotary forging, these lattice defects increase the atomic diffusion rate, thereby accelerating the formation of Al-Ca precipitates during flash annealing, and these precipitates further increase the strength of the alloy. Therefore, the present application uses element design and combines rotary forging and flash annealing processes to prepare a magnesium alloy that has both excellent high strength and high plasticity.

[0030] In some preferred embodiments, the high-strength and high-plasticity magnesium alloy is composed of the following elemental components in mass percentage: aluminum 5% to 6%, calcium 0.7% to 0.8%, and the balance is magnesium and unavoidable impurities, wherein the unavoidable impurities are ≤ 0.05%. For example, aluminum can be 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6%, or any point value within the sub-range composed of the above specific values. For example, calcium can be 0.7%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%, or any point value within the sub-range composed of the above specific values. When the mass percentage of each element is within the above range, the comprehensive mechanical properties of the magnesium alloy will reach the best.

[0031] In some preferred embodiments, the high-strength and high-plasticity magnesium alloy is composed of the following elemental components in the following mass percentages: 5.8% aluminum, 0.76% calcium, and the balance being magnesium and unavoidable impurities.

[0032] The present application also provides a method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, comprising the following steps:

[0033] Determine the raw material composition according to the designed element composition, and weigh the corresponding raw materials for use, wherein the phases corresponding to the element composition in the process temperature range of homogenization heat treatment and hot extrusion treatment only include Mg phase and Al2Ca phase;

[0034] The raw materials are heated to melt under the condition of protective gas, and casting is performed after the raw materials are melted and mixed into molten metal;

[0035] The obtained alloy ingot is subjected to the homogenization heat treatment and the hot extrusion treatment in sequence;

[0036] The alloy obtained by the hot extrusion treatment is subjected to a multi-pass rotary forging treatment;

[0037] The alloy obtained by rotary forging is flash annealed and water quenched to obtain the high-strength and high-plasticity magnesium alloy.

[0038] In some preferred embodiments, the design method of the elemental composition of the high-strength and high-plasticity magnesium alloy includes: calculating the phase composition of the magnesium-aluminum-calcium ternary alloy at different temperatures through a thermodynamic ternary phase diagram, and selecting elemental compositions that only include Mg phase and Al2Ca phase in the range of 350°C to 450°C.

[0039] In some preferred embodiments, the raw material components, measured in mass percentage, include: 5% to 6% pure aluminum, 2.3% to 2.7% magnesium-30wt.% calcium master alloy, and the rest is pure magnesium.

[0040] In some preferred embodiments, the protective gas is a mixed gas of CO2 and SF6 or a mixed gas of argon and SF6; the heating temperature of the raw material is 680°C to 720°C.

[0041] In some preferred embodiments, the homogenization heat treatment is performed at a temperature of 350° C. to 450° C. for a time of 12 hours to 24 hours.

[0042] In some preferred embodiments, when performing the hot extrusion treatment, the alloy is first preheated for 10 minutes to 20 minutes, and then extruded at 250°C to 350°C.

[0043] In some preferred embodiments, there is no limit on the number of times of the multi-pass rotary forging process, as long as the total equivalent effect variable is 10% to 20%.

[0044] In some preferred embodiments, the flash annealing treatment is performed by induction heating, and the heating time is 5 seconds to 20 seconds and the heating temperature is 400° C. to 450° C.

[0045] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solution of the present application. Unless otherwise specified, the reagents and raw materials used can be purchased through commercial channels. The experimental methods in the following examples that do not specify specific conditions are selected according to conventional methods and conditions, or according to the product specifications.

[0046] Example 1

[0047] This embodiment provides a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, which is composed of the following elemental components in mass percentage: 5.8% aluminum, 0.76% calcium, and the balance being magnesium and unavoidable impurities ≤0.05%.

[0048] This embodiment also provides a method for preparing the high-strength and high-plasticity magnesium alloy, comprising the following steps:

[0049] (1) Determine the mass of pure aluminum, magnesium-30wt.% calcium master alloy and pure magnesium based on the elemental composition and weigh them for later use;

[0050] (2) Under the protection of a mixed gas of CO2 and SF6 with a volume ratio of 50:1, pure aluminum, magnesium-30wt.% calcium master alloy and pure magnesium are smelted at 700°C, and after they are completely melted into molten metal, the molten metal is gravity cast;

[0051] (3) subjecting the obtained alloy ingot to homogenization heat treatment at 450° C. for 24 hours;

[0052] (4) Perform hot extrusion treatment by preheating the alloy for 15 minutes and then extruding it at 250°C;

[0053] (5) At room temperature, the extruded alloy was subjected to multiple rotary forging treatments, and the total equivalent effect variable was 18.3%;

[0054] (6) induction heating the swaged alloy for 10 seconds at a temperature of 450°C;

[0055] (7) After the induction heating is completed, water quenching is quickly performed to obtain the high-strength and high-plasticity magnesium alloy.

[0056] Comparative Example 1

[0057] This comparative example provides a commercial AZ31 magnesium alloy, the element composition of which is: 3% aluminum, 1% zinc, and 96% magnesium.

[0058] This comparative example also provides a method for preparing the commercial AZ31 magnesium alloy, comprising the following steps:

[0059] (1) Determine the mass of pure aluminum, pure zinc and pure magnesium based on the elemental composition and weigh them for later use;

[0060] (2) Under the protection of a mixed gas of CO2 and SF6 with a volume ratio of 50:1, pure aluminum, pure zinc and pure magnesium are smelted at 700°C, and after they are completely melted into molten metal, the molten metal is gravity cast;

[0061] (3) subjecting the obtained alloy ingot to homogenization heat treatment at 400° C. for 24 hours;

[0062] (4) Perform hot extrusion treatment by preheating the alloy for 15 minutes and then extruding it at 300°C.

[0063] Comparative Example 2

[0064] This comparative example provides a magnesium alloy whose element composition is the same as that of comparative example 1.

[0065] Compared with the preparation method of the magnesium alloy in Comparative Example 1, the preparation method of the magnesium alloy in this comparative example is different in that it further includes the following steps (5) to (7):

[0066] (5) At room temperature, the extruded alloy was subjected to multiple rotary forging treatments, and the total equivalent effect variable was 18.3%;

[0067] (6) induction heating the swaged alloy for 10 seconds at a temperature of 450°C;

[0068] (7) After the induction heating is completed, water quenching is quickly performed to obtain the magnesium alloy.

[0069] Comparative Example 3

[0070] This comparative example provides a magnesium alloy whose elemental composition is the same as that of Example 1. Compared with the preparation method of the high-strength and high-plasticity magnesium alloy of Example 1, the preparation method of the magnesium alloy of this comparative example is different in that the process steps of multiple rotary forging, induction heating and water quenching are not performed.

[0071] Transmission electron microscopy (TEM) test

[0072] The magnesium alloys prepared in Example 1 and Comparative Example 2 were subjected to transmission electron microscope testing. The testing method was as follows: a thin slice with a diameter of 3 mm and a thickness of 0.5 mm was obtained by wire cutting with electric sparks, and then mechanically ground and polished and thinned to a perforation using an ion thinning instrument. The perforated thin slice was placed in a Talos F200X G2 transmission electron microscope for observation. The results are as follows: Figure 1 and Figure 2 shown. Figure 1 It is shown in Example 1 that there is a large amount of<c+a> Dislocation, and Figure 2 It is difficult to observe in the sample of Comparative Example 2<c+a> This is because the twinning of the alloy of Example 1 was suppressed during rotary forging, which promoted<c+a> The formation of dislocations, while flash annealing only removes the faster climbing Dislocation, and<c+a> The slower dislocation climb rate is retained.

[0073] Electron Backscatter Diffraction (EBSD) and Scanning Electron Microscope (SEM) Tests

[0074] Electron backscatter diffraction test was performed on the magnesium alloys prepared in Example 1, Comparative Example 1 and Comparative Example 3. The test method was as follows: the magnesium alloy sample was wire-cut into small pieces of 5 mm × 5 mm × 3 mm for easy observation, inlaid with conductive resin, and surface ground with 320 mesh, 1000 mesh and 2000 mesh sandpaper respectively, and then polished with 3 μm, 1 μm and 0.02 μm diamond suspension polishing liquid, and finally vibrated polished with 0.02 μm diamond suspension polishing liquid to remove the stress layer to obtain a sample that can be used for EBSD observation, and the EBSD experiment was performed using a TESCAN GAIA3 scanning electron microscope with a voltage of 20 kV. The SEM experiment was performed using a TESCAN GAIA3 scanning electron microscope with a voltage of 5 kV.

[0075] Figure 3 The starting ratios of various slip systems in Example 1 (AX61-FA), Comparative Example 3 (AX61-EX) and Comparative Example 1 (AZ31-EX) at 4% strain were statistically analyzed by electron backscatter diffraction and scanning electron microscopy, wherein Figure a is a locally enlarged EBSD image of Example 1; Figure b is a SEM image of the corresponding area of ​​Figure a, and the red solid line marks the slip direction of the corresponding grain; Figure c is the marking result of the slip direction of some grains in Example 1, the blue solid line represents basal slip, the yellow solid line represents cylindrical slip, the green solid line represents primary conical slip (conical slip I), and the red solid line represents secondary conical slip (conical slip II); Figure d shows the statistical results of the starting ratios of various slip systems at 4% strain. The results show that Example 1 has the largest number of<c+a> Dislocations (marked in red in the figure).

[0076] Tensile properties test

[0077] The magnesium alloys prepared in Example 1 and Comparative Examples 1 to 3 were subjected to wire cutting to obtain tensile specimens with a gauge section size of 17 mm×3.8 mm×1.5 mm. The tensile specimens were placed in an MTS E43 tensile machine for room temperature uniaxial tensile testing at a strain rate of 0.5 mm / s. Figure 4 The tensile performance test diagrams of Example 1 and Comparative Example 3 are shown in FIG. Figure 5 The tensile performance test diagram of Comparative Example 1 and Comparative Example 2 is shown.

[0078] Since there is only Al2Ca second phase in the extruded alloy of Example 1, it is easier to suppress twinning during rotary forging and promote<c+a> Dislocations are formed, so it has good plasticity, and after rotary forging, a large amount of<c+a> Dislocations are formed and are retained after annealing, so that both strength and plasticity are improved. Furthermore, a large number of lattice defects exist in the alloy after rotary forging, and these lattice defects increase the atomic diffusion rate, thereby accelerating the formation of Al-Ca precipitation phase during annealing, so that the strength is further improved. Therefore, compared with Comparative Examples 1 to 3, the embodiments of the present application can significantly improve the strength and plasticity of the magnesium alloy.

[0079] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present application. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the contents disclosed in the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. A high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, characterized in that: The high-strength and high-plasticity magnesium alloy is obtained by sequentially subjecting the raw materials to smelting and mixing, casting, homogenizing heat treatment, hot extrusion treatment, and multiple rotary forging treatments, flash annealing treatments, and water quenching, and the elemental components of the high-strength and high-plasticity magnesium alloy correspond to phases including only Mg phase and Al2Ca phase in the process temperature range of the homogenizing heat treatment and the hot extrusion treatment.

2. The high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 1, characterized in that: The smelting and mixing is carried out under the condition of protective gas, and the smelting temperature is 680°C to 720°C; And / or, the temperature of the homogenization heat treatment is 350° C. to 450° C., and the time is 12 hours to 24 hours; and / or, when performing the hot extrusion treatment, preheating for 10 to 20 minutes and then extruding at 250° C. to 350° C.; and / or, the total equivalent effect variable of the multi-pass rotary forging process is 10% to 20%; And / or, the flash annealing treatment adopts induction heating, and the heating temperature is 400° C. to 450° C., and the heating time is 5 seconds to 20 seconds.

3. The high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 1, characterized in that: The high-strength and high-plasticity magnesium alloy is composed of the following element components in mass percentage: 5% to 6% aluminum, 0.7% to 0.8% calcium, and the balance being magnesium and unavoidable impurities ≤0.05%.

4. A method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing, characterized in that: include: Determine the raw material composition according to the designed element composition, and weigh the corresponding raw materials for use, wherein the phases corresponding to the element composition in the process temperature range of homogenization heat treatment and hot extrusion treatment only include Mg phase and Al2Ca phase; The raw materials are heated to melt under the condition of protective gas, and casting is performed after the raw materials are melted and mixed into molten metal; The obtained alloy ingot is subjected to the homogenization heat treatment and the hot extrusion treatment in sequence; The alloy obtained by the hot extrusion treatment is subjected to a multi-pass rotary forging treatment; The alloy obtained by rotary forging is flash annealed and water quenched to obtain the high-strength and high-plasticity magnesium alloy.

5. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 4, characterized in that: The total equivalent effect variable of the multi-pass rotary forging process is 10% to 20%.

6. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 4, characterized in that: The flash annealing treatment adopts an induction heating method, and the heating temperature is 400° C. to 450° C., and the heating time is 5 seconds to 20 seconds.

7. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 4, characterized in that: The design method of the element composition of the high-strength and high-plasticity magnesium alloy includes: calculating the phase composition of the magnesium-aluminum-calcium ternary alloy at different temperatures through a thermodynamic ternary phase diagram, and selecting element compositions that only include Mg phase and Al2Ca phase in the range of 350°C to 450°C.

8. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 7, characterized in that: The raw material components, measured in mass percentage, include: 5% to 6% pure aluminum, 2.3% to 2.7% magnesium-30wt.% calcium master alloy, and the rest is pure magnesium.

9. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 4, characterized in that: The temperature of the homogenization heat treatment is 350°C to 450°C, and the time is 12 hours to 24 hours; and / or, when performing the hot extrusion treatment, the alloy is first preheated for 10 minutes to 20 minutes, and then extruded at 250°C to 350°C.

10. The method for preparing a high-strength and high-plasticity magnesium alloy based on rotary forging and flash annealing according to claim 4, characterized in that: The protective gas is a mixed gas of CO2 and SF6 or a mixed gas of argon and SF6; the heating temperature of the raw material is 680°C to 720°C.

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