Preparation method of double-stage precipitation strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy

Abstract

The invention belongs to the technical field of magnesium alloy processing, and specifically relates to a preparation method of a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy. In the Mg-Zn-Cu alloy, the mass fractions of two elements, Zn and Cu, are ≤4%, and the rest is Mg; and the contents of Zn and Cu are equal; the alloy is firstly smelted to obtain cast Mg-Zn-Cu; then the cast Mg-Zn-Cu is repeatedly homogenized; the homogenized Mg-Zn-Cu is subjected to hot extrusion deformation treatment, the extrusion angle is 90 degrees, the extrusion speed is 0.4 mm / s, the extrusion ratio is 25:1, and the extrusion temperature is 220 degrees Celsius to 240 degrees Celsius; the invention realizes micron-level and nanometer-level precipitation strengthening by setting the Zn / Cu ratio, low alloying, extrusion temperature and 90 degrees extrusion angle, and balances thermal conductivity while enhancing mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of magnesium alloy processing, and relates to a preparation method of a double-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy. Background Art

[0002] As electronic devices continue to develop towards miniaturization and high performance, heat dissipation has become a key factor limiting their performance and reliability. In addition to optimizing the device structure, designing and developing lightweight and highly thermally conductive structural materials is particularly important for improving the heat dissipation performance of the device. Magnesium alloy is the lightest structural material. The thermal conductivity of pure magnesium at room temperature reaches 156W / (m·K), second only to copper and aluminum. It is a potential thermal conductive structural material.

[0003] Although pure magnesium has high thermal conductivity, its insufficient mechanical properties limit its application. The introduction of solute atoms through alloying can improve its mechanical properties (such as increasing the tensile strength to more than 200MPa), but at the same time it will reduce the thermal conductivity, which is due to the scattering effect of solute atoms on electrons. Precipitation strengthening provides a solution, which reduces the solute atoms in the matrix by forming a second phase, improves thermal conductivity, and hinders dislocation movement to enhance mechanical properties. For example, Li Zixin's research at Shanghai Jiaotong University showed that the introduction of Al in Mg-4Sm-2.6Al alloy allows Sm to form a micron-sized AlSm phase with Al, thereby improving thermal conductivity. However, such micron-sized particles may limit the overall performance due to size and distribution problems. To overcome these limitations, Qiao Xiaoguang of Harbin Institute of Technology studied the formation of a nanoscale second phase, a dynamically precipitated α-Mn phase formed in a Mg-2Mn-2.5La alloy, which increased the thermal conductivity to 135W / (m·K). Li Kun from Chongqing University successfully prepared nano-scale metastable phases in WE43 magnesium alloy by laser powder bed melting and subsequent aging treatment. Another method is to use immiscible metals to prepare metal composite materials. For example, Wu Xuebang from the Chinese Academy of Sciences prepared Cu-W alloys using spark plasma sintering technology to evenly distribute extremely fine W nanoparticles in the Cu matrix, enhancing the strength, ductility and thermal conductivity of the alloy. Other studies, such as the patent CN11557284A disclosed that the conductivity of a cast Mg-3Zn-2Cu alloy is as high as 21.03MS / m, corresponding to a thermal conductivity of about 147W / (m·K); and the patent CN117778784A mentioned a Mg-3Zn-3Cu-0.6Mn alloy extruded at 260°C, with a thermal conductivity of 125.3W / (m·K); but these technologies cannot effectively take into account both mechanical properties and thermal conductivity. Summary of the invention

[0004] The present invention overcomes the shortcomings of the prior art and proposes a method for preparing a double-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy; by achieving micron-level and nano-level precipitation strengthening, the mechanical properties of the magnesium alloy are enhanced while the thermal conductivity is balanced.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy comprises the following steps:

[0007] S1. Composition design: In Mg-Zn-Cu alloy, the mass fraction of Zn and Cu is ≤4%, and the rest is Mg; and the content of Zn and Cu is equal;

[0008] S2, alloy smelting to obtain cast Mg-Zn-Cu;

[0009] S3, repeatedly homogenizing the cast Mg-Zn-Cu; the homogenizing is to heat the cast Mg-Zn-Cu to 400°C~450°C and keep it for 15h~25h, and then immediately water-cooling;

[0010] S4. The homogenized Mg-Zn-Cu is subjected to hot extrusion deformation treatment; the hot extrusion deformation has an extrusion angle of 90°, an extrusion speed of 0.4 mm / s, an extrusion ratio of 25:1, and an extrusion temperature of 220°C to 240°C.

[0011] Preferably, the repeated homogenization treatment in step S3 is to place the cast Mg-Zn-Cu into a vacuum heat treatment furnace, heat it to 430°C and keep it for 20 hours and then immediately water cool it to room temperature, and then repeat the above operation 3 times, so that the total homogenization time is 60 hours.

[0012] Preferably, before the hot extrusion deformation treatment, the homogenized Mg-Zn-Cu is preheated, and the preheating temperature is consistent with the extrusion temperature and is kept warm for 1h~2h, and then the hot extrusion deformation is performed.

[0013] Preferably, the Mg—Zn—Cu subjected to hot extrusion deformation treatment is cooled to room temperature by a water mist method.

[0014] Preferably, the alloy smelting equipment adopts a box-type resistance furnace, and argon is used as the protective gas during the smelting process.

[0015] Preferably, before alloy smelting, the oxide layer on the surface of the raw materials of Mg, Zn and Cu is removed, and all the raw materials are placed in a drying oven and dried at a temperature of 200℃~220℃ for 0.5h~1h; the covering agent and refining agent are ground into powder and placed in a drying oven to be dried together; at the same time, the mold with the surface evenly coated with a release agent is placed in a drying oven and preheated at a temperature of 200℃~220℃.

[0016] More preferably, after the raw materials are dried, the magnesium is melted first, then the zinc is melted, and then the copper is melted.

[0017] More preferably, the magnesium is melted by placing dried pure magnesium into a crucible, sprinkling a covering agent on the surface, closing the furnace cover and passing argon gas for protection, raising the temperature to 720°C at a rate of 10°C / min and keeping the temperature for 30 minutes to completely melt the pure magnesium.

[0018] More preferably, when adding zinc to melt, after the pure magnesium has melted and been kept warm, open the furnace cover to remove the slag, then add pure zinc, evenly sprinkle the covering agent, close the furnace cover, raise the temperature to 750°C at 10°C / min and keep it warm for 5 minutes.

[0019] Better yet, add copper to melt after zinc has melted and been kept warm, scrape off the scum on the surface of the melt, then add pure copper, stir for 2 minutes after the copper sheet turns dark red, then evenly sprinkle the covering agent and close the furnace cover, and keep the temperature of the resistance furnace until it reaches 750℃, and keep it warm for 5 minutes.

[0020] Principles of alloy design of the present invention:

[0021] In the alloy design, in order to maintain excellent thermal conductivity while improving mechanical properties, the present invention selects zinc (Zn) elements that have little effect on thermal conductivity, and copper (Cu) elements that can change the second phase morphology of magnesium-zinc (Mg-Zn) alloys and increase the solid solubility of elements, to achieve the preparation of high thermal conductivity deformable magnesium alloys. Zn can improve the tensile strength of Mg alloys, but it will reduce the elongation and increase the tendency of hot cracking and shrinkage. For this reason, the Cu element is added to the Mg-Zn base alloy because it has a grain refinement effect and can also transform the MgZn phase into a continuous network of MgZnCu phase, thereby increasing the eutectic temperature of the alloy and making high-temperature homogenization treatment possible. This not only increases the solid solubility of Zn and Cu, but also forms a supersaturated solid solution, laying the foundation for the subsequent realization of micron- and nano-scale dual-stage precipitation strengthening.

[0022] The present invention forms a supersaturated solid solution by reducing the alloying degree and homogenizing. In the hot extrusion process, combined with plastic deformation, the defect density is increased to provide nucleation points for nano-scale precipitation phases. Zn and Cu elements in the matrix are dynamically precipitated during the plastic deformation process to form nano-scale precipitation phases, and micron-scale precipitation phases are precipitated during the extrusion process. These precipitation phases are combined with the MgZnCu broken during the plastic deformation process to form micron-scale and nano-scale dual-stage precipitation strengthening, thereby effectively balancing thermal conductivity and mechanical properties.

[0023] The present invention studies the influence of hot deformation on the structure and properties of Mg-Zn-Cu magnesium alloys, as well as the influence of extrusion temperature on their thermal conductivity and mechanical properties, and elaborates on the effects of hot extrusion and extrusion temperature on the α-Mg matrix and MgZnCu phase. By adjusting the extrusion temperature, the relationship between the alloy's thermal conductivity, mechanical properties and organizational changes is revealed, thereby successfully preparing a Mg-Zn-Cu high thermal conductivity deformable magnesium alloy with dual-stage precipitation strengthening characteristics.

[0024] The beneficial effects of the present invention compared with the prior art are as follows:

[0025] 1. The present invention proposes to use low alloy content and micron-level and nano-level dual-level precipitation strengthening to balance the thermal conductivity and mechanical properties of the material. Nano-level precipitation phase can be achieved by rapid solidification and metal-based material composite preparation. Rapid solidification technology produces a supersaturated solid solution through rapid cooling and promotes nano-phase precipitation through heat treatment.

[0026] 2. Compared with the existing methods, the present invention adopts homogenization treatment combined with plastic deformation to form nano-scale precipitation phase. A supersaturated solid solution is formed by homogenization, and high-density dislocations and grain boundaries are introduced by hot extrusion to provide nucleation sites for nano-phase precipitation, thereby forming a nano-scale precipitation phase. Compared with the laser powder bed fusion method and metal-based composite materials, the method of the present invention has a simple process and a denser structure after hot extrusion molding, with low porosity, low surface roughness after extrusion molding, many selectable alloy systems, and low equipment cost.

[0027] 3. The present invention achieves micron-level and nanometer-level precipitation strengthening by setting the Zn / Cu ratio, low alloying, extrusion temperature and 90° extrusion angle, thereby balancing thermal conductivity while enhancing mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of the method for preparing the double-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy of the present invention;

[0029] Figure 2The scanning microstructure photos of the cast and extruded alloys of Mg-1Zn-1Cu and Mg-2Zn-2Cu alloys in the embodiments are shown in Figure 1; (a) is cast Mg-1Zn-1Cu; (b) is Mg-1Zn-1Cu extruded at 220°C; (c) is Mg-1Zn-1Cu extruded at 240°C; (d) is cast Mg-2Zn-2Cu; (e) is Mg-2Zn-2Cu extruded at 220°C; (f) is Mg-2Zn-2Cu extruded at 240°C;

[0030] Figure 3 The mechanical properties of the cast and extruded alloys of Mg-1Zn-1Cu and Mg-2Zn-2Cu alloys in the embodiments;

[0031] Figure 4 is the thermal conductivity of the cast and extruded alloys of the Mg-1Zn-1Cu and Mg-2Zn-2Cu alloys in the embodiments. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail in conjunction with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention are described in detail below in conjunction with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0033] See also Figure 1 This embodiment provides a method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy; specifically comprising the following steps:

[0034] S1. Composition design

[0035] In order to achieve high thermal conductivity, the alloying degree in this embodiment is relatively low, the total alloying element content (mass fraction) is ≤4%, and the Zn and Cu contents are set equal. This embodiment designs two groups of magnesium alloy systems with different alloying degrees and equal Zn and Cu contents, namely: Mg-1Zn-1Cu and Mg-2Zn-2Cu.

[0036] S2. Alloy smelting

[0037] This example uses high-purity magnesium ingots, high-purity zinc ingots and high-purity copper sheets as raw materials, uses a box-type resistance furnace as the smelting equipment, and uses argon as the protective gas during the smelting process to prepare two groups of magnesium alloy samples, Mg-1Zn-1Cu and Mg-2Zn-2Cu. The detailed steps are as follows:

[0038] S2.1. Raw material preparation: remove the oxide layer on the surface of the raw material and dry it in a drying oven at 200°C for 30 minutes; grind the covering agent and refining agent into powder using a grinding mortar and dry them together in a drying oven; at the same time, put the mold with the release agent evenly coated on the surface into a drying oven and preheat it at 200°C;

[0039] S2.2. Melting pure magnesium: Place a crucible with an inner wall coated with ZnO into a resistance furnace, then heat the resistance furnace to 500°C at 10°C / min, place the dried pure magnesium into the crucible, sprinkle a covering agent on its surface, close the furnace cover and pass argon gas for protection. Magnesium alloy is a highly active and thermodynamically unstable material. During the smelting process, molten magnesium tends to react violently with oxygen in the air. Therefore, argon gas and salt covering agents are used for protection during the smelting process. Raise the temperature to 720°C at 10°C / min and keep it warm for 30 minutes to completely melt the pure magnesium;

[0040] S2.3, adding zinc: after the insulation is finished, open the furnace cover to remove the slag, then add pure zinc, evenly sprinkle the covering agent, close the furnace cover, increase the temperature to 750℃ at 10℃ / min and keep it warm for 5 minutes;

[0041] S2.4, add copper: after the insulation is finished, use a slag rod to scrape off the slag on the surface of the melt, then add pure copper, stir with a stirring rod for 2 minutes after the copper sheet turns dark red, then evenly sprinkle the covering agent and close the furnace cover. After the temperature of the resistance furnace rises to 750℃, keep it warm for 5 minutes;

[0042] S2.5. Composition detection: After the heat preservation is completed, a sampling spoon is used to take a sample and a spectrometer is poured to test the sample. After the test is completed, the burnt loss during the smelting process is supplemented. For Mg-1Zn-1Cu, the mass percentage of Zn is supplemented to 1%, the mass percentage of Cu is supplemented to 1%, and the rest is Mg, to obtain a magnesium alloy melt; for Mg-2Zn-2Cu, the mass percentage of Zn is supplemented to 2%, the mass percentage of Cu is supplemented to 2%, and the rest is Mg, to obtain a magnesium alloy melt;

[0043] S2.6, Refining: Lower the temperature of the resistance furnace to 730℃, remove the surface scum with a slag rod, add the refining agent, and stir it thoroughly with a stirring rod for 2-3 minutes, then evenly sprinkle the covering agent, close the furnace, raise the temperature to 750℃, and let it stand for 20 minutes;

[0044] S2.7. Pouring: After the insulation is completed, the temperature of the resistance furnace is lowered to 730°C, the surface scum is removed, and the magnesium alloy melt is poured into the preheated mold. After the mold temperature cools to room temperature, the cast alloy sample is taken out.

[0045] S3. Homogenization

[0046] Homogenization treatment was performed on two groups of alloys, Mg-1Zn-1Cu and Mg-2Zn-2Cu. Before homogenization treatment, cylindrical samples with a size of Φ80mm×20mm were cut from the cast alloy samples using a lathe; differential thermal analysis (DSC) was performed on the cast alloy samples at the same time. The results showed that an endothermic peak appeared at 470℃, indicating that the second phase in the alloy melted. To avoid overburning of the second phase, the solution temperature was set to 430℃. Then, the cast alloy samples were subjected to multiple homogenization treatments for a total time of 60h in a vacuum heat treatment furnace to obtain the homogenized alloy samples. The detailed steps were as follows: the cast alloy samples were placed in a vacuum heat treatment furnace, heated to 430℃ and kept warm for 20h, and then the cast alloy samples were immediately water-cooled to room temperature, and then the above operation was repeated 3 times to ensure that the total homogenization time was 60h.

[0047] Traditional homogenization treatment usually involves heating the alloy to a specific temperature and keeping it warm for a period of time to eliminate the uneven distribution of chemical components inside the material. However, long-term high-temperature insulation will cause grain coarsening, thereby reducing the mechanical properties of the material. In order to solve this problem, the present invention adopts a method of multiple homogenization treatments, and divides the homogenization process into multiple times while keeping the total high-temperature insulation time unchanged. This method effectively reduces the negative impact of grain coarsening while achieving uniform composition.

[0048] S4. Hot extrusion deformation

[0049] The surface of the homogenized alloy sample is polished to ensure the smoothness of the extruded surface. The homogenized alloy sample is preheated before extrusion, and the preheating temperature is consistent with the extrusion temperature and kept warm for 1 hour. After that, the alloy is hot extruded and deformed, and the extruded sample is cooled to room temperature by water mist method. The extrusion parameters used in this embodiment are as follows: the extrusion die angle is 90°, the extrusion speed is 0.4mm / s, and the extrusion ratio is 25:1; the extrusion temperature is 240℃ and 220℃; that is, two parallel samples of the two magnesium alloys Mg-1Zn-1Cu and Mg-2Zn-2Cu are taken, and the two parallel samples of each magnesium alloy are processed by the following two hot extrusion parameters:

[0050] (1) The extrusion angle is 90°, the extrusion speed is 0.4 mm / s, the extrusion ratio is 25:1, and the extrusion temperature is 240 °C;

[0051] (2) The extrusion angle is 90°, the extrusion speed is 0.4 mm / s, the extrusion ratio is 25:1, and the extrusion temperature is 220 °C;

[0052] The extrusion temperatures selected in this embodiment are 240°C and 220°C, respectively, and the extrusion speed is 0.4mm / s. The use of low temperature and slow extrusion can effectively reduce the heat generated between the billet and the sleeve due to friction during the extrusion process, thereby limiting the growth of dynamically recrystallized grains. In addition, low temperature and slow extrusion can also make the fluidity of the material change less, which helps to achieve uniform distribution of the structure. The extrusion ratio selected in this embodiment is 25:1, and the extrusion die angle is 90°. Through the combination of a large extrusion ratio and a flat die, the lateral shear stress on the billet can be increased during the extrusion process, and the dead zone of the billet that does not participate in the flow and deformation during the extrusion process can be reduced, thereby improving the uniformity of material deformation and making the alloy structure more uniform.

[0053] S5. Results Analysis

[0054] (1) The cast alloy consists of an α-Mg matrix and granular and semi-continuous network MgZnCu phases. After homogenization and hot extrusion deformation, the morphology of the MgZnCu phase changes to a granular state, and nanoscale precipitates dynamically precipitate in the matrix during the extrusion process (see Figure 2 ). After hot extrusion deformation, due to dynamic recrystallization, the grain size of the alloy is reduced, and the dual-stage precipitation strengthening at the micron and nano levels significantly improves the mechanical properties of the alloy. For the cast Mg-1Zn-1Cu alloy, its ultimate tensile strength is 109.4MPa and its elongation is 12%. After hot extrusion deformation at 220℃, the tensile strength is increased to 224.8MPa and the elongation reaches 22%; in contrast, after hot extrusion deformation at 240℃, the tensile strength is 217.9MPa and the elongation is 21%. For the cast Mg-2Zn-2Cu alloy, its ultimate tensile strength is 104.8MPa and its elongation is 8%. After hot extrusion deformation at 220℃, the tensile strength is increased to 222.8MPa and the elongation is 12%; in contrast, after hot extrusion deformation at 240℃, the tensile strength is 222.1MPa and the elongation reaches 25%; (see Table 1 and Figure 3 ).

[0055]

[0056] (2) The cast Mg-1Zn-1Cu alloy has a higher thermal conductivity of 145.4W / (m·K) in the cast state due to the use of fewer alloying elements. After hot extrusion deformation, micron- and nano-scale double-stage precipitation strengthening forms precipitation phases, reducing the solute atoms in the matrix, thereby improving the thermal conductivity. In the extruded state at 220°C, the thermal conductivity rises to 149.5W / (m·K), and further increases to 151.9W / (m·K) in the extruded state at 240°C. In comparison, the thermal conductivity of the cast Mg-2Zn-2Cu alloy is 132.2W / (m·K) due to the introduction of more solute atoms. After homogenization treatment and hot extrusion deformation at 220°C, the thermal conductivity of this alloy increases significantly to 150.1W / (m·K); after extrusion deformation at 240°C, the thermal conductivity is 149.7W / (m·K); (see Table 2 Figure 4 ).

[0057]

[0058] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy, characterized in that: The following steps are involved: S1. Composition design: In Mg-Zn-Cu alloy, the mass fraction of Zn and Cu is ≤4%, and the rest is Mg; and the content of Zn and Cu is equal; S2, alloy smelting to obtain cast Mg-Zn-Cu; S3, repeatedly homogenizing the cast Mg-Zn-Cu; the repeated homogenizing is to put the cast Mg-Zn-Cu into a vacuum heat treatment furnace, heat it to 430°C and keep it for 20 hours, then immediately cool it to room temperature with water, and then repeat the above operation 3 times, so that the total homogenization time is 60 hours; S4. The homogenized Mg-Zn-Cu is subjected to hot extrusion deformation treatment; the hot extrusion deformation has an extrusion angle of 90°, an extrusion speed of 0.4 mm / s, an extrusion ratio of 25:1, and an extrusion temperature of 220°C to 240°C.

2. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 1, characterized in that: Before the hot extrusion deformation treatment, the homogenized Mg-Zn-Cu is preheated, and the preheating temperature is consistent with the extrusion temperature and kept warm for 1h~2h, and then the hot extrusion deformation is carried out.

3. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 1, characterized in that: The Mg-Zn-Cu after hot extrusion deformation was cooled to room temperature by water spray method.

4. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 1, characterized in that: The alloy smelting equipment adopts a box-type resistance furnace, and argon is used as the protective gas during the smelting process.

5. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 4, characterized in that: Before alloy smelting, remove the surface oxide layer of Mg, Zn and Cu raw materials, and put all raw materials into a drying oven for drying at 200℃~220℃ for 0.5h~1h; grind the covering agent and refining agent into powder and put them into the drying oven for drying together; at the same time, put the mold with the surface evenly coated with release agent into the drying oven for preheating at 200℃~220℃.

6. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 5, characterized in that: After the raw materials are dried, magnesium is melted first, then zinc is added to melt, and then copper is added to melt.

7. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 6, characterized in that: To melt magnesium, put the dried pure magnesium into a crucible, sprinkle a covering agent on its surface, close the furnace cover and use argon gas for protection, raise the temperature to 720°C at 10°C / min and keep it warm for 30 minutes to completely melt the pure magnesium.

8. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 7, characterized in that: Zinc is added for melting. After the pure magnesium is melted and the insulation is completed, the furnace cover is opened to remove the slag, and then pure zinc is added. After the covering agent is evenly sprinkled, the furnace cover is closed and the temperature is raised to 750℃ at 10℃ / min and kept warm for 5 minutes.

9. The method for preparing a two-stage precipitation-strengthened Mg-Zn-Cu high thermal conductivity deformable magnesium alloy according to claim 8, characterized in that: When adding copper to melt, wait until zinc is melted and the insulation is finished, scrape off the slag on the surface of the melt, and then add pure copper. After the copper sheet turns dark red, stir for 2 minutes, then evenly sprinkle the covering agent and close the furnace cover. After the temperature of the resistance furnace rises to 750℃, keep it warm for 5 minutes.

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