Metal injection molding method for Al-Si-Mg series aluminum alloy

Abstract

The present invention discloses a metal injection molding method for Al-Si-Mg aluminum alloy. First, the aluminum alloy powder raw material is weighed according to the stoichiometric ratio according to the design formula, and pre-treated, and then the aluminum alloy powder raw material and the binder are mixed and granulated to obtain uniform feed, and the feed is injected into the mold cavity by injection molding technology to obtain a green product, and then the green product is subjected to the first hot degreasing and hot isostatic pressing forming treatment, and finally the second hot degreasing, sintering densification and solution aging heat treatment are completed in sequence to obtain an aluminum alloy product. Compared with the prior art, the present invention, on the basis of metal injection molding technology, adopts powder pretreatment and green embryo hot isostatic pressing and other technical means to prepare aluminum alloy parts with excellent performance, which has the advantages of good mechanical properties, high density, high production efficiency, and easy to realize mass production. The tensile strength of the obtained aluminum alloy product is ≥240MPa, the elongation is ≥1.5%, and the density is ≥95%, which is comparable to cast aluminum alloy products and can well meet customer needs.

Description

Technical Field

[0001] The invention relates to a method for preparing an aluminum alloy, in particular to a metal injection molding method for an Al-Si-Mg series aluminum alloy. Background Art

[0002] Aluminum is the most abundant element in the earth's crust, second only to oxygen and silicon, and its relative density is only 2.7g / cm -3 , has high ductility, high electrical conductivity and thermal conductivity, and can react with oxygen in the air to form a corrosion-resistant oxide film, forming a good protective effect. Nowadays, the demand for lightweight development of products is increasing. Aluminum alloys with low density and high specific strength after alloying are used as the preferred metal for lightweight solutions and have been widely used in manufacturing industries such as aircraft, automobiles, trains and ships.

[0003] Al-Si-Mg alloys not only have excellent corrosion resistance, fatigue resistance and castability, but also due to the presence of Mg element, Al-Si-Mg alloys can obtain dispersed Mg2Si phase after heat treatment, which plays a strengthening role. Therefore, this series of aluminum alloys also have higher specific strength and better comprehensive mechanical properties, and are relatively mature lightweight materials.

[0004] Aluminum has a strong affinity for oxygen, especially powder. When aluminum powder is exposed to the air, a nano-scale Al2O3 film will soon form on the surface. This film has a strong insulating effect and can isolate the matrix from the outside world, so aluminum alloys often have strong corrosion resistance and oxidation resistance. However, the presence of the surface oxide film also brings difficulties to the preparation. The raw materials need to remove the oxide film before they can effectively contact and form a metallurgical bond. At present, the main process methods to solve this problem are casting, warm pressing, high-speed pressing and powder forging. Except for casting, these other methods are without exception to apply a large pressure to deform the powder, physically break the oxide film, and make the powder effectively contact. Metal injection molding (MIM) cannot provide the metallurgical effect of casting and the pressure required to break the oxide film during the forming process, so there are great difficulties in preparing aluminum alloys using the MIM method. The patent "A method for preparing high-performance aluminum alloy using powder injection molding technology" (CN107790729B) believes that in addition to this problem, there are two other difficulties: First, due to the high proportion of organic binder in the injection molded blank, the internal porosity of the blank after degreasing is much larger than that of the pressed blank; second, aluminum powder has the characteristic of hygroscopicity, which will react with oxygen radicals and water vapor, further increasing the thickness of the oxide film on the surface of the powder, and will also cause powder agglomeration, resulting in uneven feeding composition. As a result, it is very difficult to apply MIM technology to aluminum alloy production. At present, there are few achievements in this regard. However, compared with traditional casting and powder metallurgy technology, MIM has great advantages in the preparation of high-performance complex structural parts. The prepared parts have uniform organization, high density, high shape accuracy, good surface finish, and are near-net forming technology, which is efficient and low cost in mass production. Summary of the invention

[0005] In order to solve the problems existing in the prior art, an Al-Si-Mg aluminum alloy injection molding method is provided. On the basis of MIM technology, technical means such as powder pretreatment and green embryo hot isostatic pressing are introduced to prepare aluminum alloy products with excellent performance and stable quality, further promoting the application of MIM aluminum alloy in aerospace, automotive industry, electronic information and other fields.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The invention discloses a metal injection molding method for an Al-Si-Mg series aluminum alloy. The specific preparation steps are as follows: firstly, aluminum alloy powder raw materials are weighed according to a designed formula and a stoichiometric ratio, and pre-processed, then the aluminum alloy powder raw materials and a binder are mixed and granulated to obtain a uniform feed, the feed is injected into a mold cavity by an injection molding technology to obtain a product green body, then the green body is subjected to a first hot degreasing and hot isostatic pressing forming treatment, and finally a second hot degreasing, sintering densification and solid solution aging heat treatment are sequentially performed to obtain an aluminum alloy product.

[0008] The pretreatment comprises drying and dispersing treatment, wherein the aluminum alloy powder raw material is placed in a vacuum drying oven, a desiccant is placed in the drying oven, the temperature is kept at 80 to 90° C. for 10 to 12 hours, and the powder is dispersed by using an ultrasonic vibration screen after cooling;

[0009] The desiccant is one of calcium chloride, silica gel or molecular sieve desiccant;

[0010] The hot isostatic pressing process is as follows: the forming temperature is 130-150° C., the forming pressure is 110 MPa-140 MPa, and the sheath material is rubber or plastic.

[0011] In a preferred embodiment, the aluminum alloy product comprises the following components by mass percentage: Si: 6.5-8.5%, Mg: 2-4%, and the balance is Al.

[0012] According to a preferred embodiment, the aluminum alloy powder raw materials are: Zl101 pre-alloyed powder (main elements are Al, Si, Mg), Al-12Si alloy powder, Al-50Mg alloy powder, and Al powder; the particle size of Zl101 pre-alloyed powder is ≤18μm, and the purity is ≥99.9%; the particle size of Al-12Si powder is ≤25μm, and the purity is ≥99.0%; the particle size of Al-50Mg is ≤25μm, and the purity is ≥99.5%; the particle size of Al powder is ≤25μm, and the purity is ≥99.7%.

[0013] In a preferred embodiment, the binder is composed of the following components by mass percentage:

[0014]

[0015] According to a preferred embodiment, in the feed material, the volume ratio of the aluminum alloy powder raw material to the binder is 66-70%:30-34%; the mixing process is as follows: the mixing temperature is 150-160° C., and the mixing time is 1-5 hours.

[0016] In a preferred embodiment, the injection molding process is as follows: mold temperature is 60-80° C., injection temperature is 160-190° C., and injection pressure is 110 MPa-130 MPa.

[0017] The preferred solution is that the first thermal degreasing process is: first vacuumizing, then heating, and the vacuum degree is less than or equal to 10 -3 Pa, heat up to 250-280°C at 1-5°C / min, keep warm for 60-120min and then cool with the furnace.

[0018] In a preferred embodiment, the hot isostatic pressing process is as follows: the forming temperature is 130-150° C., the forming pressure is 110 MPa-140 MPa, and the sheath material is rubber or plastic.

[0019] The preferred solution is that the second thermal debinding and sintering densification are integrated into one process, specifically: vacuuming first, then heating, and the vacuum degree is less than or equal to 10 -3 Pa, first heat up to 370-400°C at 1-3°C / min, keep warm for 60-90min, then heat up to 580-600°C at 1-3°C / min, keep warm for 60-120min and then cool with the furnace.

[0020] The preferred solution aging heat treatment process is: solution treatment is: first vacuumize, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, heating to 520-540℃ at 8-10℃ / min, keeping temperature for 4-6h, water quenching; aging treatment: vacuumizing first, then heating, vacuum degree is less than or equal to 10 -3 Pa, heat to 150-170°C at 6-8°C / min, keep warm for 1-4h, and cool in air.

[0021] Principles and advantages

[0022] The present invention utilizes metal injection molding technology and simultaneously introduces technical means such as powder pretreatment and green embryo hot isostatic pressing to prepare Al-Si-Mg series aluminum alloys with performance comparable to that of casting alloys, thereby providing a method for preparing high-quality aluminum alloy products.

[0023] The present invention adds a relatively high content of Mg in the form of Al-50Mg, and has two purposes: first, an oxide film exists on the surface of the aluminum-containing powder raw material, which hinders sintering. Mg is the main component for breaking the oxide film. A sufficient Mg content ensures the film breaking effect, and the Al-50Mg component is located near the eutectic point component of the aluminum-magnesium binary phase diagram, which is conducive to the formation of an aluminum-magnesium eutectic liquid phase and accelerates the film breaking; second, the Mg element reacts with the Si element to generate a strengthening phase Mg2Si. After breaking the Al2O3 film to form Al-Mg oxide, the Mg content is still sufficient to react with Si to generate a strengthening phase, thereby ensuring good mechanical properties after heat treatment.

[0024] The binder components used in the present invention are palm wax (CW), ethylene-vinyl acetate copolymer (EVA), high-density polyethylene (HDPE), random polypropylene (APP) and stearic acid (SA). The selected binder components are not easy to absorb moisture and do not react with powders. After mixing, they can form an effective package to prevent the metal powder from increasing the thickness of the oxide film due to moisture absorption. Among the components, CW has a low melting point and a fast decomposition rate at about 250°C. It can be quickly removed at a relatively low temperature. At the same time, the viscosity is relatively small in the melted state, which can reduce the viscosity and improve the fluidity of the feed. In order to prevent the problem of deformation caused by the excessive removal of a single component during the second degreasing, polymers with different decomposition temperatures are selected as binder support components after CW is removed, and HDPE and APP are selected as supports after CW is removed to maintain the shape and strength of the green body. APP and HDPE have poor compatibility. In order to prevent uneven mixing, a small amount of EVA is selected to be added as a compatibilizer to improve the uniformity of the feed and prevent powder agglomeration. Stearic acid is used as a surfactant. Since catalytic degreasing can easily aggravate moisture absorption and increase the thickness of the oxide film, and solvent degreasing is time-consuming and the green embryo is easily deformed, the present invention adopts two thermal degreasing methods under a vacuum environment to complete the removal of the binder, and pre-dries and disperses the powder before forming, effectively solving the problem that aluminum alloy powder is easy to absorb moisture and agglomerate, resulting in uneven mixing and thickening of the oxide film.

[0025] The present invention introduces hot isostatic pressing technology after the first hot debinding of the product to ensure uniform force on all parts of the product, more consistent density of the blank at all parts, and make up for the density reduced due to low injection pressure, so that the structure after sintering is more uniform and dense, further ensuring the product size accuracy and sintering quality.

[0026] The product prepared by the present invention has higher performance, with tensile strength of ≥240MPa, elongation of ≥1.5%, and density of ≥95%, which is comparable to the strength of aluminum alloys with similar components prepared by a casting method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the metallographic structure diagram of the aluminum alloy sintered billet in Example 2. DETAILED DESCRIPTION

[0028] The method of the present invention is further described below in conjunction with three embodiments.

[0029] Embodiment 1:

[0030] A metal injection molding method for Al-Si-Mg aluminum alloy, the process is as follows:

[0031] A. Preparation of alloy and binder raw materials: Powder raw materials use Zl101 powder with a particle size of 18μm and a purity of ≥99.7%; Al-50Mg powder with a particle size of 25μm and a purity of ≥99.5%; Al-12Si powder with a particle size of ≤25μm and a purity of ≥99%; Al powder with a particle size of ≤25μm and a purity of ≥99.7%; the specific composition of Zl101 powder is shown in the following table:

[0032] element Al Mg Si Ti Other impurities content(%) 91.5 0.28 7.99 0.14 ≤0.1

[0033] The metal raw material powders were weighed according to the mass percentage of 6.8% Si, 2% Mg, and 91.2% Al, and 50% palm wax (CW), 25% high-density polyethylene (HDPE), 15% random polypropylene (APP), 5% ethylene-vinyl acetate copolymer (EVA), and 5% stearic acid (SA) were weighed according to the mass ratio.

[0034] B. Material pretreatment: Place metal powder, HDPE, EVA and APP in a vacuum drying oven, place molecular sieve desiccant in the drying oven, and evacuate to 10 -1 When the pressure is below Pa, the temperature is raised to 90°C and dried for 10 hours. After cooling, the mixture is sieved with an ultrasonic vibration sieve with a mesh diameter of 38 μm.

[0035] C. Feed material preparation: metal powder and binder are configured in a volume ratio of 70:30 and put into an internal mixer for mixing, and then granulated to obtain feed material. During mixing, high melting point binder ingredients are added first, and then low melting point binder ingredients are added. The subsequent powder addition principles are the same. The mixing temperature of the internal mixer is 150°C and the mixing time is 4h.

[0036] D. Injection molding: Use an injection molding machine to injection mold the feed material, the injection temperature is 165°C, and the injection pressure is 130Mpa.

[0037] E. First thermal degreasing: vacuumize first, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, heat to 260°C at 2°C / min, keep warm for 120min and then cool with the furnace.

[0038] F. Hot isostatic pressing: It is processed by hot isostatic pressing machine, the sheath material is rubber, the forming pressure is 120MPa, and the temperature is 130℃.

[0039] G. Sintering: The hot isostatic pressing blank is placed in a vacuum sintering furnace for sintering; first evacuate the vacuum, then increase the temperature, and the vacuum degree is less than or equal to 10 -3 After Pa, the temperature was first increased to 380°C at 2.5°C / min, kept at this temperature for 90min, then increased to 580°C at 2°C / min, kept at this temperature for 120min, and then cooled with the furnace.

[0040] H. Heat treatment: Use a vacuum sintering furnace to heat treat the sintered blank; 8℃ / min to 520℃, keep warm for 4h, water quench, and then put it in a drying oven for drying and standby use. After drying, perform aging treatment, 6℃ / min to aging temperature 150℃, keep warm for 2h, and air cool. After heat treatment, the mechanical properties of the product are tested, and its tensile strength is 247.5MPa, elongation is 2.1%, and density is 96%.

[0041] Embodiment 2:

[0042] A metal injection molding method for Al-Si-Mg aluminum alloy, the process is as follows:

[0043] A. Preparation of alloy and binder raw materials: Powder raw materials use Zl101 powder with a particle size of 18μm and a purity of ≥99.7%; Al-50Mg powder with a particle size of 25μm and a purity of ≥99.5%; Al-12Si powder with a particle size of ≤25μm and a purity of ≥99%; Al powder with a particle size of ≤25μm and a purity of ≥99.7%; the specific composition of Zl101 powder is shown in the following table:

[0044] element Al Mg Si Ti Other impurities content(%) 91.5 0.28 7.99 0.14 ≤0.1

[0045] The metal raw material powders were weighed according to the mass percentage of 8.5% Si, 4% Mg, and 87.5% Al, and 40% palm wax (CW), 30% high-density polyethylene (HDPE), 20% random polypropylene (APP), 8% ethylene-vinyl acetate copolymer (EVA), and 2% stearic acid (SA) were weighed according to the mass ratio.

[0046] B. Material pretreatment: Place the metal powder raw materials in a vacuum drying oven, place a molecular sieve desiccant in the drying oven, and evacuate the vacuum to 10 -1 When the pressure is below Pa, the temperature is raised to 90°C and dried for 10 hours. After cooling, the mixture is sieved with an ultrasonic vibration sieve with a mesh diameter of 38 μm.

[0047] C. Feed preparation: Metal powder and binder are configured in a volume ratio of 66:34 and put into an internal mixer for mixing, and then granulated to obtain feed. When mixing, high melting point binder ingredients are added first, and then low melting point binder ingredients are added. The subsequent powder addition principles are the same. The mixing temperature of the internal mixer is 160°C and the mixing time is 2h.

[0048] D. Injection molding: Use an injection molding machine to injection mold the feed material, the injection temperature is 190℃, and the injection pressure is 110Mpa.

[0049] E. First thermal degreasing: vacuumize first, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, heat to 280℃ at 5℃ / min, keep warm for 60min and then cool with the furnace.

[0050] F. Hot isostatic pressing: It is processed by hot isostatic pressing machine, the sheath material is plastic, the forming pressure is 130MPa, and the temperature is 135℃.

[0051] G. Sintering: The hot isostatic pressing blank is placed in a vacuum sintering furnace for sintering; first evacuate the vacuum, then increase the temperature, and the vacuum degree is less than or equal to 10 -3 After Pa, the temperature was first increased to 400°C at 3°C / min, kept at this temperature for 60min, then increased to 590°C at 2°C / min, kept at this temperature for 80min, and then cooled with the furnace.

[0052] H. Heat treatment: Use a vacuum sintering furnace to heat treat the sintered blank; 10℃ / min to 540℃, keep warm for 6h, water quench, and then put it in a drying oven for drying and standby use. After drying, perform aging treatment, 6℃ / min to aging temperature 150℃, keep warm for 4h, and air cool. After heat treatment, the mechanical properties of the product are tested, and its tensile strength is 266.7MPa, elongation is 1.7%, and density is 97%.

[0053] Embodiment 3:

[0054] A metal injection molding method for Al-Si-Mg aluminum alloy, the process is as follows:

[0055] A. Preparation of alloy and binder raw materials: Powder raw materials use Zl101 powder with a particle size of 18μm and a purity of ≥99.7%; Al-50Mg powder with a particle size of 25μm and a purity of ≥99.5%; Al-12Si powder with a particle size of ≤25μm and a purity of ≥99%; Al powder with a particle size of ≤25μm and a purity of ≥99.7%; the specific composition of Zl101 powder is shown in the following table:

[0056] element Al Mg Si Ti Other impurities content(%) 91.5 0.28 7.99 0.14 ≤0.1

[0057] The metal raw material powders were weighed according to the mass percentage of 7.5% Si, 3.5% Mg, and 89.0% Al, and 45% palm wax (CW), 23% high-density polyethylene (HDPE), 20% random polypropylene (APP), 8% ethylene-vinyl acetate copolymer (EVA), and 4% stearic acid (SA) were weighed according to the mass ratio.

[0058] B. Material pretreatment: Place the metal powder raw materials in a vacuum drying oven, place a molecular sieve desiccant in the drying oven, and evacuate the vacuum to 10 -1 When the pressure is below Pa, the temperature is raised to 90°C and dried for 10 hours. After cooling, the mixture is sieved with an ultrasonic vibration sieve with a mesh diameter of 38 μm.

[0059] C. Feed preparation: Metal powder and binder are configured in a volume ratio of 68:32 and put into an internal mixer for mixing, and then granulated to obtain feed. When mixing, high melting point binder ingredients are added first, and then low melting point binder ingredients are added. The subsequent powder addition principles are the same. The mixing temperature of the internal mixer is 160°C and the mixing time is 2h.

[0060] D. Injection molding: Use an injection molding machine to injection mold the feed material, the injection temperature is 175℃, and the injection pressure is 120Mpa.

[0061] E. First thermal degreasing: vacuumize first, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, heat to 250°C at 2°C / min, keep warm for 90 min and then cool with the furnace.

[0062] F. Hot isostatic pressing: It is processed by hot isostatic pressing machine, the sheath material is plastic, the forming pressure is 130MPa, and the temperature is 140℃.

[0063] G. Sintering: The hot isostatic pressing blank is placed in a vacuum sintering furnace for sintering; first evacuate the vacuum, then increase the temperature, and the vacuum degree is less than or equal to 10 -3 After Pa, first heat up to 370℃ at 2℃ / min, keep warm for 90min, then heat up to 600℃ at 3℃ / min, keep warm for 60min and then cool with the furnace.

[0064] H. Heat treatment: Use a vacuum sintering furnace to heat treat the sintered blank; 8℃ / min to 530℃, keep warm for 4h, water quench, and then put it in a drying oven for drying and standby use. After drying, perform aging treatment, 6℃ / min to aging temperature 160℃, keep warm for 2h, and air cool. After heat treatment, the mechanical properties of the product are tested, and its tensile strength is 251.6MPa, elongation is 1.9%, and density is 96.4%.

[0065] Comparative Example 1

[0066] This comparative example adopts a method substantially the same as that of Example 2, except that the metal powder and binder raw materials are not treated before preparation, and the surface of the final product is severely oxidized and not sintered densely.

[0067] Comparative Example 2

[0068] This comparative example adopts the same method as Example 2, except for the alloy composition. The results are shown in the following table:

[0069]

[0070] Comparative Example 3

[0071] This comparative example adopts a method substantially the same as that of Example 2, except that no hot isostatic pressing treatment is performed after the first thermal degreasing. The final product has a density of 89%, a tensile strength of 171.5 MPa, and an elongation of 0.4%.

[0072] Comparative Example 4

[0073] This comparative example adopts the method basically the same as that of Example 2, except that the hot isostatic pressing parameters are different. The specific parameters and comparative results are shown in the following table:

[0074] serial number Forming temperature / ℃ Forming pressure / MPa evaluate 1 140 90 Density 92%, tensile strength 200.2MPa 2 140 160 Green deformation 3 180 130 Binder melts, green body deforms 4 90 130 Density 93%, tensile strength 210.1MPa

[0075] Comparative Example 5

[0076] This comparative example adopts the same method as Example 2, except for the sintering process. The specific sintering process and the comparative results are shown in the following table:

[0077]

[0078] The above-described examples are only preferred implementation methods of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. Other equivalent changes, modifications, substitutions and combinations made in accordance with the principles and contents of the present invention still fall within the protection scope of the present invention.

Claims

1. A metal injection molding method for Al-Si-Mg aluminum alloy, characterized in that: The method comprises the following steps: firstly, weighing the aluminum alloy powder raw material according to the stoichiometric ratio according to the designed formula and performing pretreatment, then mixing and granulating the aluminum alloy powder raw material and the binder to obtain uniform feed, injecting the feed into the mold cavity by injection molding technology to obtain a product green body, then performing a first hot degreasing and hot isostatic pressing process on the green body, and finally performing a second hot degreasing, sintering densification and solid solution aging heat treatment in sequence to obtain an aluminum alloy product; The aluminum alloy product comprises Si: 6.5-8.5%, Mg: 2-4%, and the balance Al; The pretreatment comprises drying and dispersing treatment, wherein the aluminum alloy powder raw material is placed in a vacuum drying oven, and one of calcium chloride, silica gel or molecular sieve desiccant is placed in the drying oven, and the drying oven is kept at 80 to 90° C. for 10 to 12 hours, and after cooling, the powder is dispersed using an ultrasonic vibration sieve; The binder comprises by weight percentage: 40-50% palm wax (CW), 20-30% high-density polyethylene (HDPE), 10-20% random polypropylene (APP), 2-8% ethylene-vinyl acetate copolymer (EVA), and 2-5% stearic acid (SA); The hot isostatic pressing process is as follows: the forming temperature is 130-150° C., the forming pressure is 110 MPa-140 MPa, and the sheath material is rubber or plastic; The properties of the aluminum alloy product are: tensile strength ≥240MPa, elongation ≥1.5%, and density ≥95%.

2. The metal injection molding method of an Al-Si-Mg aluminum alloy according to claim 1, characterized in that: The aluminum alloy powder raw materials are: Zl101 pre-alloyed powder, Al-12Si alloy powder, Al-50Mg alloy powder, and Al powder; the Zl101 pre-alloyed powder has a particle size of ≤18μm and a purity of ≥99.9%; the Al-12Si powder has a particle size of ≤25μm and a purity of ≥99.0%; the Al-50Mg has a particle size of ≤25μm and a purity of ≥99.5%; and the Al powder has a particle size of ≤25μm and a purity of ≥99.7%.

3. The metal injection molding method of an Al-Si-Mg aluminum alloy according to claim 1, characterized in that: In the feed material, the volume ratio of the aluminum alloy powder raw material and the binder is 66-70%:30-34%; the mixing process is as follows: the mixing temperature is 150-160° C., and the mixing time is 1-5 hours.

4. The metal injection molding method of an Al-Si-Mg aluminum alloy according to claim 1, characterized in that: The injection molding process is: mold temperature 60-80°C, injection temperature 160-190°C, and injection pressure 110MPa-130MPa.

5. The metal injection molding method of Al-Si-Mg aluminum alloy according to claim 1, characterized in that: The first thermal degreasing process is: vacuum first, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, heat up to 250-280°C at 1-5°C / min, keep warm for 60-120min and then cool with the furnace.

6. The metal injection molding method of Al-Si-Mg aluminum alloy according to claim 1, characterized in that: The second thermal debinding and sintering densification process is integrated, specifically: vacuum first, then heat up, the vacuum degree is less than or equal to 10 -3 Pa, first heat up to 370-400°C at 1-3°C / min, keep warm for 60-90min, then heat up to 580-600°C at 1-3°C / min, keep warm for 60-120min and then cool with the furnace.

7. The metal injection molding method of Al-Si-Mg aluminum alloy according to claim 1, characterized in that: Solution treatment: vacuum first, then heat up, vacuum degree is less than or equal to 10 -3 Pa, heating to 520-540℃ at 8-10℃ / min, keeping temperature for 4-6h, water quenching; aging treatment: vacuumizing first, then heating, vacuum degree is less than or equal to 10 -3 Pa, heat to 150-170°C at 6-8°C / min, keep warm for 1-4h, and cool in air.

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