A process for forming a magnesium-aluminum alloy

Abstract

The application relates to the technical field of a metal semi-solid die-casting forming process, in particular to a magnesium-aluminum alloy forming process. The magnesium-aluminum alloy forming process comprises the following steps: magnesium-aluminum alloy smelting: firstly, magnesium-aluminum alloy powder is transferred to a smelting furnace for melting, inert gas blowing is continuously carried out on the molten liquid during the smelting process, the molten liquid is statically placed for 10-16 min after the smelting is completed, and dross is removed; semi-solid slurry preparation: the magnesium-aluminum alloy solution is transferred to a crucible, and then the magnesium-aluminum alloy solution is subjected to cooling and stirring operation; injection forming: the semi-solid slurry is subjected to injection forming through an alloy injection molding machine, and a magnesium-aluminum alloy casting is obtained after cooling. The magnesium-aluminum alloy forming process can promote the magnesium-aluminum alloy casting prepared to have a higher yield and a more excellent surface quality.

Description

Technical Field

[0001] This application relates to the technical field of metal semi-solid die casting forming process, and more specifically, it relates to a magnesium-aluminum alloy forming process. Background Technology

[0002] Magnesium-aluminum alloys are characterized by low density, high strength, good toughness, and excellent shock absorption. They also have good plasticity and machinability, so they can be processed into products of different shapes and sizes through various processing techniques such as casting, forging, extrusion, stretching, and semi-solid die casting. They are widely used in the automotive industry, aerospace, electronics, and medical devices.

[0003] Semi-solid die casting is a metal casting process that was newly developed in the early 1970s. Compared with the traditional die casting process, it can make the alloy products produced have finer grains and more uniform microstructure. At the same time, the matrix shrinkage is reduced, the tendency to hot cracking is decreased, the tendency to shrinkage porosity in the matrix is ​​eliminated, the mechanical properties are greatly improved, the solidification shrinkage is small, and the forming accuracy is high. Therefore, it has gradually replaced the traditional die casting process.

[0004] However, the semi-solid die casting process has high requirements for raw materials, especially when processing thin-walled magnesium-aluminum alloy parts, which has the disadvantages of low yield and poor surface quality. Therefore, there is still room for improvement in the semi-solid die casting process for magnesium-aluminum alloys. Summary of the Invention

[0005] In order to improve the defects of low yield and poor surface quality when preparing thin-walled magnesium-aluminum alloy parts by semi-solid die casting process, this application provides a magnesium-aluminum alloy forming process.

[0006] This application provides a magnesium-aluminum alloy forming process, which adopts the following technical solution:

[0007] A magnesium-aluminum alloy forming process includes the following steps:

[0008] Magnesium-aluminum alloy smelting: First, transfer the magnesium-aluminum alloy powder to a smelting furnace for melting. During the smelting process, inert gas is continuously injected into the molten liquid. The inert gas is one or a mixture of nitrogen and argon. The smelting temperature is between 510-620℃. Melt until the hydrogen content of the molten liquid is <0.2cc / 100g. After smelting, let it stand for 10-16 minutes and skim off the slag.

[0009] The magnesium-aluminum alloy contains 11%-14% Al, and is doped with Ce, Ti and Yb.

[0010] Semi-solid slurry preparation: The magnesium-aluminum alloy solution is transferred to a crucible, and then cooled and stirred. Cooling is carried out by cooling air until the solution temperature is between 450-470℃ and the solid content in the slurry is greater than 40%.

[0011] Injection molding: Semi-solid slurry is injection molded using an alloy injection molding machine and cooled to obtain magnesium-aluminum alloy castings.

[0012] During the smelting process, magnesium-aluminum alloys are prone to reacting with oxygen in the air due to excessively high temperatures, resulting in the presence of oxide inclusions and gases in the melt. If purification treatment is not performed, casting defects such as shrinkage cavities, porosity, and cracks are easily generated when preparing magnesium-aluminum alloy castings, leading to low yield and poor surface quality of magnesium-aluminum alloy castings.

[0013] In response, the applicant continuously sprays inert gas into the molten metal during the smelting process, causing the inert gas to form bubbles in the melt. Due to the pressure difference between the inert gas and the alloy melt, hydrogen in the melt enters the inert gas bubbles under the action of the pressure difference, and then leaves the metal melt by floating up. At the same time, the wettability of the bubbles with metal oxide impurities is used to adsorb and carry away the oxide impurities from the melt, thereby achieving the purpose of removing hydrogen and impurities, and thus significantly improving the yield and surface quality of magnesium-aluminum alloy castings.

[0014] Furthermore, magnesium-aluminum alloys have poor fluidity, making them prone to casting defects such as shrinkage cavities, porosity, and cracks when preparing thin-walled magnesium-aluminum alloy castings. Currently, to improve the fluidity of magnesium-aluminum alloys, the Al content is usually increased. However, excessively high Al content will also lead to increased brittleness in magnesium-aluminum alloy castings, i.e., deterioration of mechanical properties, thus affecting the normal use of magnesium-aluminum alloy castings.

[0015] Rare earth elements can enhance the strength and toughness of magnesium-aluminum alloys by altering grain size and morphology. Specifically, the addition of Ce significantly reduces the crystal size of magnesium-aluminum alloys. This is because Ce can suppress the interaction forces between components in the alloy, thereby lowering the crystallization temperature and promoting grain growth. Furthermore, Ce has a high specific surface area and a high melting point, allowing it to form a stable structure within the grains, thus inhibiting crack propagation. In addition, Ce possesses good magnetic properties, generating a magnetic field effect within the grains, further improving the mechanical properties of the magnesium-aluminum alloy. The addition of Ti and Yb can affect the ductility and toughness of magnesium-aluminum alloys, thereby further reducing the brittleness of high-aluminum magnesium-aluminum alloys.

[0016] Preferably, in the magnesium-aluminum alloy smelting process, the inert gas is injected by rotary injection.

[0017] When inert gas is continuously injected into the molten metal, if a rotating nozzle is used for rotary injection, the force generated by the rotation will cause the inert bubbles to undergo strong shearing with the molten metal, causing the bubbles to break into uniformly distributed fine bubbles. The bubbles rise in a spiral manner, which helps to increase the contact time and area between the bubbles and the magnesium-aluminum alloy molten metal, further improving the molten metal purification efficiency and promoting the yield and surface quality of magnesium-aluminum alloy castings.

[0018] Preferably, in the preparation of the semi-solid slurry, the cooling air flow rate is 35-45 L / min.

[0019] When preparing semi-solid slurry, if a faster cooling air flow rate of 35-45 L / min is selected, the solidification rate of the melt will also increase, thereby promoting the gradual transformation of the grain morphology of magnesium-aluminum alloy towards spherical grains, instead of transforming into other grains such as stripes or dendrites, thus obtaining better mechanical properties, ultimately resulting in a very high yield and extremely good product surface quality.

[0020] Preferably, in the preparation of the semi-solid slurry, the stirring is carried out by a biaxial stirrer, and the stirring directions of the two stirring rods are opposite, and the stirring blades of the two stirring rods are interlaced and parallel.

[0021] Preferably, in the preparation of the semi-solid slurry, the stirring speed is 600-800 rpm.

[0022] When a single-axis stirrer is used for stirring, the slurry grains at the edge of the crucible are spherical, with finer grain size, higher roundness, and uniform grain distribution. However, the grains at the center of the crucible are usually strip-shaped, dendritic, or other types. The reason for this is that during stirring, the edge near the crucible wall experiences greater shear force, resulting in more intense collisions and friction between the alloy melts. At the same time, the melt also interacts with the crucible wall, leading to more complete dendrite breakage and thus obtaining grains with better morphology.

[0023] In this application, a twin-shaft agitator is used for stirring, and the stirring directions of the two stirring rods are opposite. The stirring blades of the two stirring rods are interlaced and parallel. As a result, during the stirring process, each area of ​​the slurry has extremely strong shear force, which promotes a more perfect and uniform grain morphology of the magnesium-aluminum alloy slurry, and further improves the yield and surface quality of the magnesium-aluminum alloy castings.

[0024] A faster stirring speed can further increase the shear force, but an excessively fast stirring speed will lead to larger grain size, which will affect the mechanical properties of magnesium-aluminum alloys. Therefore, it is better to control the stirring speed at 600-800 rpm.

[0025] Preferably, the magnesium-aluminum alloy comprises the following raw materials in the following mass percentages: Al 11-14%, Ce 0.5-2.0%, Ti 0.1-1.0%, Yb 0.1-1.0%, Zn 0.1-1.0%, Mn 0.2-0.4%, with the balance being Mg and unavoidable impurities.

[0026] Preferably, the mass ratio of Ce, Ti, and Yb is 1:(0.1-0.3):(0.2-0.4).

[0027] However, excessive rare earth elements can lead to numerous defects and cracks within the magnesium-aluminum alloy crystals, making the alloy more prone to fracture. Therefore, a reasonable ratio of Ce, Ti, and Yb is necessary to ensure that the magnesium-aluminum alloy possesses both superior fluidity and mechanical properties. In this application, experiments revealed that when the magnesium-aluminum alloy contains 11-14% Al, 0.5-2.0% Ce, 0.1-1.0% Ti, and 0.1-1.0% Yb, with a mass ratio of Ce, Ti, and Yb of 1:(0.1-0.3):(0.2-0.4), the resulting magnesium-aluminum alloy exhibits both superior fluidity and mechanical properties, ultimately resulting in an extremely high yield and excellent surface quality.

[0028] Preferably, Ce, Ti and Yb are added to the magnesium-aluminum alloy in the form of a Ce-Ti-Yb master alloy.

[0029] When Ce, Ti, and Yb are first prepared into a Ce-Ti-Yb master alloy and then added to a magnesium-aluminum alloy, Ce, Ti, and Yb will more easily and conveniently form rare earth phases, thereby making Ce, Ti, and Yb more effective in improving the mechanical properties of the magnesium-aluminum alloy.

[0030] Preferably, in the injection molding process, the injection speed is 0.05-0.15 m / s.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. During the smelting process, continuous inert gas injection into the molten metal can promote the formation of bubbles in the inert gas within the melt. Due to the pressure difference between the inert gas and the alloy melt, hydrogen in the melt enters the inert gas bubbles under the action of the pressure difference, and then leaves the molten metal through the rising of the bubbles. At the same time, the wettability of the bubbles with metal oxide impurities is used to adsorb and carry away the oxide impurities from the melt, thereby achieving the purpose of removing hydrogen and impurities, and thus significantly improving the yield and surface quality of magnesium-aluminum alloy castings.

[0033] 2. When a rotary nozzle is used for rotary blowing, the force generated by the rotation will cause the inert bubbles to undergo strong shearing with the melt, causing the bubbles to break into uniformly distributed fine bubbles. The bubbles rise in a spiral manner, which helps to increase the contact time and area between the bubbles and the magnesium-aluminum alloy melt, further improving the melt purification efficiency and promoting the yield and surface quality of magnesium-aluminum alloy castings.

[0034] 3. Rare earth elements can improve the strength and toughness of magnesium-aluminum alloys by altering grain size and morphology. Specifically, when Ce is added to magnesium-aluminum alloys, the crystal size decreases significantly. This is because Ce can suppress the interaction forces between the components in the alloy, thereby lowering the crystallization temperature and promoting grain growth. Furthermore, Ce has a high specific surface area and a high melting point, allowing it to form a stable structure within the grains, thus inhibiting crack propagation. In addition, Ce possesses good magnetic properties, generating a magnetic field effect within the grains, further enhancing the mechanical properties of the magnesium-aluminum alloy. Adding Ti and Yb to magnesium-aluminum alloys can affect their ductility and toughness, thereby further reducing the brittleness of high-aluminum magnesium-aluminum alloys. Detailed Implementation

[0035] The present application will be further described in detail below with reference to Examples 1-10 and Comparative Examples 1-2.

[0036] raw material

[0037] Al CAS: 7429-90-5; Ce CAS: 7440-45-1; Ti CAS: 7440-32-6; Yb CAS: 7440-64-4; Zn CAS: 7440-66-6; Mn CAS: 7439-96-5; Mg CAS: 7439-95-4.

[0038] Example 1

[0039] A magnesium-aluminum alloy forming process includes the following steps:

[0040] Magnesium-aluminum alloy smelting: First, transfer the magnesium-aluminum alloy powder to the smelting furnace for melting. During the smelting process, inert gas is continuously injected into the molten liquid. The inert gas is argon. The smelting temperature is between 510-620℃. Melt until the hydrogen content of the molten liquid is <0.2cc / 100g. After the smelting is completed, let it stand for 15 minutes and skim off the slag.

[0041] The magnesium-aluminum alloy comprises the following raw materials by mass percentage: Al 13%, Ce 1%, Ti 0.2%, Yb 0.3%, Zn 0.4%, Mn 0.3%, with the balance being Mg and unavoidable impurities;

[0042] The preparation process of magnesium-aluminum alloy is as follows: Al, Ce, Ti, Yb, Zn, Mn and Mg are mixed in proportion, and then melted in a melting furnace at a melting temperature of 510-620℃. After melting, the alloy is cooled and crushed to obtain magnesium-aluminum alloy powder.

[0043] Semi-solid slurry preparation: The magnesium-aluminum alloy solution was transferred to a crucible, and then cooled and stirred. Cooling was carried out with cooling air at a flow rate of 35 L / min until the solution temperature was between 450-470℃ and the solid content in the slurry was greater than 40%.

[0044] Injection molding: Semi-solid slurry is injection molded using an alloy injection molding machine and cooled to obtain magnesium-aluminum alloy castings. The injection speed is 0.10 m / s, the alloy injection molding machine model is Haitian-1300T, and the molding and cooling processes are conventional.

[0045] Example 2

[0046] The difference from Example 1 is that in the magnesium-aluminum alloy smelting, the inert gas is injected by rotary injection, that is, a rotary nozzle is used for inert gas injection.

[0047] Example 3

[0048] The difference from Example 2 is that the cooling air flow rate is 40 L / min in the preparation of the semi-solid slurry.

[0049] Example 4

[0050] The difference from Example 2 is that the cooling air flow rate is 45 L / min in the preparation of the semi-solid slurry.

[0051] Example 5

[0052] The difference from Example 3 is that in the preparation of the semi-solid slurry, the stirring is carried out by a biaxial stirrer, and the stirring directions of the two stirring rods are opposite. The stirring blades of the two stirring rods are interlaced and parallel, and the stirring speed is 600 rpm.

[0053] Example 6

[0054] The difference from Example 5 is that the stirring speed is 700 rpm.

[0055] Example 7

[0056] The difference from Example 5 is that the stirring speed is 800 rpm.

[0057] Examples 8-9

[0058] The difference from Example 6 is that the mass percentages of each component in the magnesium-aluminum alloy are different, as shown in Table 1.

[0059] Table 1. Mass percentage of each component in the magnesium-aluminum alloy of Examples 6 and 8-9

[0060] Example 6 Example 8 Example 9 Al 13 14 11 Ce 1 1 1 Ti 0.2 0.1 0.3 Yb 0.3 0.4 0.2 Zn 0.4 0.1 1.0 Mn 0.3 0.4 0.2 Mg and impurities margin margin margin

[0061] Example 10

[0062] The difference from Example 6 is that Ce, Ti, and Yb are added to the magnesium-aluminum alloy in the form of a Ce-Ti-Yb master alloy;

[0063] The preparation process of Ce-Ti-Yb master alloy is as follows: Ce, Ti and Yb are mixed in proportion, and then melted in a melting furnace at a temperature between 800-900℃. After melting, the alloy is cooled and crushed to obtain magnesium-aluminum alloy powder.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that inert gas blowing is no longer performed during the magnesium-aluminum alloy smelting.

[0066] Comparative Example 2

[0067] The difference from Example 1 is that Ce, Ti and Yb are no longer added to the magnesium-aluminum alloy.

[0068] Performance testing

[0069] Using Examples 1-10 and Comparative Examples 1-2 as raw materials, 1 mm thick boards were prepared. One thousand samples were prepared, and the pass rate of the boards was recorded. Boards with defects such as shrinkage cavities, cracks, and peeling on the surface were considered unqualified products. At the same time, samples were also knocked. If cracks or other defects occurred after knocking, the samples were also defined as unqualified products. The test data are shown in Table 2.

[0070] Table 2. Detection data of Examples 1-10 and Comparative Examples 1-2

[0071] pass rate pass rate Example 1 93.8% Example 7 98.6% Example 2 95.2% Example 8 97.9% Example 3 96.5% Example 9 98.1% Example 4 96.2% Example 10 99.8% Example 5 98.4% Comparative Example 1 81.3% Example 6 98.9% Comparative Example 2 87.9%

[0072] Referring to Example 1 and Comparative Example 1 and in conjunction with Table 2, it can be seen that the pass rate of Comparative Example 1 is significantly lower than that of Example 1. This indicates that inert gas blowing during the smelting process of magnesium-aluminum alloy can effectively improve the pass rate of magnesium-aluminum alloy castings.

[0073] The reason for this is that during the smelting process of magnesium-aluminum alloys, the temperature is too high, which makes them easily react with oxygen in the air, resulting in the presence of oxide inclusions and gases in the melt. If purification treatment is not performed, casting defects such as shrinkage cavities, porosity, and cracks are easily generated when preparing magnesium-aluminum alloy castings, resulting in low yield and poor surface quality of magnesium-aluminum alloy castings.

[0074] During the smelting process, inert gas is continuously injected into the molten metal, causing the inert gas to form bubbles in the melt. Due to the pressure difference between the inert gas and the alloy melt, hydrogen in the melt enters the inert gas bubbles under the action of the pressure difference, and then leaves the metal melt by floating up. At the same time, the wettability of the bubbles with metal oxide impurities is used to adsorb and carry out the oxide impurities from the melt, thereby achieving the purpose of removing hydrogen and impurities. This significantly improves the yield and surface quality of magnesium-aluminum alloy castings.

[0075] Referring to Example 1 and Comparative Example 1 and in conjunction with Table 2, it can be seen that the pass rate of Comparative Example 2 is also significantly lower than that of Example 1. This indicates that adding Ce, Ti, and Yb to magnesium-aluminum alloys can effectively improve the pass rate of magnesium-aluminum alloy castings.

[0076] The reason for this is that magnesium-aluminum alloys have poor fluidity, which makes them prone to casting defects such as shrinkage cavities, porosity, and cracks when preparing thin-walled magnesium-aluminum alloy castings. Currently, in order to improve the fluidity of magnesium-aluminum alloys, the Al content is usually increased. However, excessively high Al content will also lead to increased brittleness of magnesium-aluminum alloy castings, that is, a deterioration in mechanical properties, which in turn affects the normal use of magnesium-aluminum alloy castings.

[0077] Rare earth elements can enhance the strength and toughness of magnesium-aluminum alloys by altering grain size and morphology. Specifically, the addition of Ce significantly reduces the crystal size of magnesium-aluminum alloys. This is because Ce can suppress the interaction forces between components in the alloy, thereby lowering the crystallization temperature and promoting grain growth. Furthermore, Ce has a high specific surface area and a high melting point, allowing it to form a stable structure within the grains, thus inhibiting crack propagation. In addition, Ce possesses good magnetic properties, generating a magnetic field effect within the grains, further improving the mechanical properties of the magnesium-aluminum alloy. The addition of Ti and Yb can affect the ductility and toughness of magnesium-aluminum alloys, thereby further reducing the brittleness of high-aluminum magnesium-aluminum alloys.

[0078] Referring to Examples 1 and 2 and in conjunction with Table 2, it can be seen that the pass rate of Example 2 is further improved compared to Example 1. This indicates that when using rotary blowing for inert gas blowing, the pass rate of the prepared aluminum-magnesium alloy castings will be relatively higher.

[0079] The reason for this is that when inert gas is continuously sprayed onto the molten metal, if a rotating nozzle is used for rotary spraying, the force generated by the rotation will cause the inert bubbles to undergo strong shearing with the melt, causing the bubbles to break into uniformly distributed fine bubbles. These bubbles rise in a spiral manner, which helps to increase the contact time and area between the bubbles and the magnesium-aluminum alloy molten metal, further improving the melt purification efficiency and thus further improving the yield and surface quality of magnesium-aluminum alloy castings.

[0080] Referring to Examples 2-4 and Table 2, it can be seen that as the cooling air flow rate increases, the pass rate of magnesium-aluminum alloy castings will gradually increase. However, when the cooling air flow rate reaches 40 L / min, further increasing the cooling air flow rate will not significantly change the pass rate of magnesium-aluminum alloy castings. This indicates that when the cooling air flow rate is 40 L / min, magnesium-aluminum alloy castings will achieve a better pass rate.

[0081] The reason for this is that when preparing semi-solid slurry, using a faster cooling air flow rate can significantly increase the solidification rate of the melt, thereby causing the grain morphology of magnesium-aluminum alloy to gradually transform into spherical grains instead of other grains such as strips or dendrites. This results in better mechanical properties and ultimately leads to a very high yield and excellent product surface quality.

[0082] Referring to Examples 3 and 5 and in conjunction with Table 2, it can be seen that the pass rate of Example 5 is further improved compared to Example 3. This indicates that when the stirring is carried out by a biaxial stirrer in the preparation of semi-solid slurry, and the stirring directions of the two stirring rods are opposite, and the stirring blades of the two stirring rods are interlaced and parallel, the magnesium-aluminum alloy castings will have a better pass rate.

[0083] The reason for this is that when a single-axis stirrer is used for stirring, the slurry grains at the edge of the crucible are spherical, with finer grain size, higher roundness, and uniform grain distribution. However, the grains in the center of the crucible are usually strip-shaped, dendritic, or other types of grains. This is because, during the stirring process, the edge near the crucible wall experiences greater shear force, resulting in more intense collisions and friction between the alloy melts. At the same time, the melt also interacts with the crucible wall, leading to more complete dendrite breakage and thus obtaining grains with better morphology.

[0084] When a twin-shaft agitator is used for mixing, with the two agitators moving in opposite directions and their blades intersecting and parallel, the slurry exhibits extremely strong shear force in all areas. This results in a more perfect and uniform grain morphology in the magnesium-aluminum alloy slurry, further improving the yield and surface quality of magnesium-aluminum alloy castings.

[0085] Referring to Examples 5-7 and Table 2, it can be seen that Example 6 has a relatively higher pass rate, while the pass rates of Examples 5 and 7 are relatively low. This indicates that when using a twin-shaft mixer, the pass rate of magnesium-aluminum alloy castings will gradually increase with the increase of the stirring speed. However, when the stirring speed reaches 700 rpm, if the stirring speed is further increased, the pass rate of magnesium-aluminum alloy castings will actually decrease.

[0086] The reason is that a faster stirring speed can further increase the shear force, but too fast a stirring speed will lead to larger grain size, which will affect the mechanical properties of magnesium-aluminum alloy. Therefore, it is better to control the stirring speed at 700 rpm.

[0087] Referring to Examples 6 and 8-9 and in conjunction with Table 2, it can be seen that the pass rates of Examples 8 and 9 are relatively lower than those of Example 6. This indicates that when the components of the magnesium-aluminum alloy adopt the mass percentages of Example 6, the magnesium-aluminum alloy will have better fluidity, toughness and mechanical properties.

[0088] The reason is that although the addition of rare earth elements can effectively improve the strength and toughness of magnesium-aluminum alloys, too many rare earth elements will cause a large number of defects and cracks in the crystals of magnesium-aluminum alloys, making them more prone to fracture. Therefore, the addition of Ce, Ti and Yb needs to be properly proportioned to enable magnesium-aluminum alloys to have both better fluidity and mechanical properties.

[0089] Experiments have shown that when the magnesium-aluminum alloy contains 13% Al, 1% Ce, 0.2% Ti, 0.3% Yb, 0.4% Zn, and 0.3% Mn, with the balance being Mg and unavoidable impurities, the resulting magnesium-aluminum alloy will have both superior fluidity and mechanical properties, ultimately exhibiting extremely high yield and excellent surface quality.

[0090] Referring to Examples 6 and 10 and in conjunction with Table 2, it can be seen that the pass rate of Example 10 is further improved compared to Example 6. This indicates that when Ce, Ti and Yb are added to magnesium-aluminum alloys in the form of Ce-Ti-Yb master alloys, the resulting magnesium-aluminum alloys will have better fluidity, toughness and mechanical properties.

[0091] The reason for this is that when Ce, Ti, and Yb are first prepared into a Ce-Ti-Yb master alloy and then added to the magnesium-aluminum alloy, Ce, Ti, and Yb will more easily and conveniently form rare earth phases, thereby making Ce, Ti, and Yb more effective in improving the mechanical properties of the magnesium-aluminum alloy.

[0092] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A magnesium-aluminum alloy forming process, characterized in that, Includes the following steps: Magnesium-aluminum alloy smelting: First, transfer the magnesium-aluminum alloy powder to a smelting furnace for melting. During the smelting process, inert gas is continuously injected into the molten liquid. The inert gas is one or a mixture of nitrogen and argon. The smelting temperature is between 510-620℃. Melt until the hydrogen content of the molten liquid is <0.2cc / 100g. After smelting, let it stand for 10-16 minutes and skim off the slag. The magnesium-aluminum alloy contains 11%-14% Al, and is doped with Ce, Ti and Yb. Semi-solid slurry preparation: The molten magnesium-aluminum alloy is transferred to a crucible, and then cooled and stirred. Cooling is carried out by cooling air until the molten temperature is between 450-470℃ and the solid content in the slurry is greater than 40%. Injection molding: Semi-solid slurry is injected into a mold using an alloy injection molding machine and cooled to obtain magnesium-aluminum alloy castings; The magnesium-aluminum alloy comprises the following raw materials in the following mass percentages: Al 11-14%, Ce 0.5-2.0%, Ti 0.1-1.0%, Yb 0.1-1.0%, Zn 0.1-1.0%, Mn 0.2-0.4%, with the balance being Mg and unavoidable impurities.

2. The magnesium-aluminum alloy forming process according to claim 1, characterized in that: In the magnesium-aluminum alloy smelting process, the inert gas is injected by rotary jetting.

3. The magnesium-aluminum alloy forming process according to claim 1, characterized in that: In the preparation of the semi-solid slurry, the cooling air flow rate is 35-45 L / min.

4. The magnesium-aluminum alloy forming process according to claim 1, characterized in that: In the preparation of the semi-solid slurry, stirring is carried out by a biaxial stirrer, with the two stirring rods stirring in opposite directions and the stirring blades of the two stirring rods intersecting and parallel to each other.

5. The magnesium-aluminum alloy forming process according to claim 4, characterized in that: In the preparation of the semi-solid slurry, the stirring speed is 600-800 rpm.

6. The magnesium-aluminum alloy forming process according to claim 1, characterized in that: The mass ratio of Ce, Ti, and Yb is 1:(0.1-0.3):(0.2-0.4).

7. The magnesium-aluminum alloy forming process according to claim 6, characterized in that: The Ce, Ti, and Yb are added to the magnesium-aluminum alloy in the form of a Ce-Ti-Yb master alloy.

8. The magnesium-aluminum alloy forming process according to claim 1, characterized in that: In the injection molding process, the injection speed is 0.05-0.15 m / s.