Silicon carbide reinforced aluminum-based composite material and pressureless infiltration large-scale preparation method thereof

Abstract

The invention discloses a silicon carbide reinforced aluminum-based composite material and a pressureless infiltration large-scale preparation method thereof, and belongs to the technical field of metal-based composite material preparation. The silicon carbide reinforced aluminum-based composite material comprises an aluminum matrix, silicon carbide reinforcements are distributed in the aluminum matrix, the silicon carbide reinforcements are silicon carbide particle accumulation bodies, the aluminum matrix is Al-Si-Mg aluminum alloy, the mass percent of Si in the Al-Si-Mg aluminum alloy is 12%-16%, and the mass percent of Mg in the Al-Si-Mg aluminum alloy is 3%-7%. The Al-Si-Mg aluminum alloy contains a Ti element, and the mass percent of the Ti element is 1%-3%. According to the silicon carbide reinforced aluminum-based composite material and the pressureless infiltration large-scale preparation method thereof, the components of the Al-Si-Mg aluminum alloy are adjusted, and the Ti element is added, so that the preparation of a silicon carbide reinforced aluminum-based composite material large-size billet is realized, and the bending strength of the composite material is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of metal matrix composites, and particularly to a silicon carbide reinforced aluminum matrix composite and a method for its large-scale preparation by pressureless infiltration. Background Art

[0002] Characteristics such as low expansion, high specific modulus, high thermal conductivity, and high resonant frequency enable high-volume fraction silicon carbide particle-reinforced aluminum matrix composites to simultaneously possess excellent structural load-bearing functions, excellent thermal control functions, and unique anti-resonance functions. This new material has been applied in small batches in aerospace precision instruments and military electronic components in our country, and significant application results have been achieved.

[0003] The pressureless infiltration method is an effective process for preparing such composites. It not only has a short process flow and high production efficiency, but also the silicon carbide particles are evenly distributed in the aluminum alloy matrix and the billet size has good stability. The preparation of large-sized billets requires higher temperatures and longer holding times to achieve the spontaneous and complete infiltration of silicon carbide particle accumulations with larger projected areas and greater depths. However, maintaining a high temperature for too long will significantly increase the tendency of harmful interfacial chemical reactions between molten aluminum and silicon carbide, seriously damage the material properties, and even produce interfacial chemical reaction products - Al4C3, resulting in severe deliquescence and pulverization of the composite material. Due to this technical difficulty, the billet sizes of high-volume fraction silicon carbide particle-reinforced aluminum matrix composites prepared by the pressureless infiltration method at home and abroad are very limited at present, and only billets with a projected area of about 1 square meter and a thickness of less than 140 mm can be stably produced.

[0004] The existing Al-Si-Mg ternary matrix alloy has a low pressureless infiltration rate. If complete infiltration of large billets is to be achieved, either the process holding time is extended or the process holding temperature is increased, both of which will bring an obvious tendency of harmful interfacial chemical reactions between molten aluminum and silicon carbide. The high-reliability and high-quality preparation of large-sized silicon carbide-reinforced Al-Si-Mg composite billets is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a silicon carbide reinforced aluminum matrix composite and a method for its large-scale preparation by pressureless infiltration. By adjusting the composition of Al-Si-Mg aluminum alloy and adding Ti element, the preparation of large-sized silicon carbide-reinforced aluminum alloy composite billets is realized, and the bending strength of the composite billets is significantly improved.

[0006] To achieve the above object, the present invention provides a silicon carbide reinforced aluminum matrix composite material, which includes an aluminum matrix, and silicon carbide reinforcements are distributed inside the aluminum matrix. The silicon carbide reinforcements are silicon carbide particle aggregates, and the aluminum matrix is an Al-Si-Mg aluminum alloy. In the Al-Si-Mg aluminum alloy, the mass percentage of Si element is 12% - 16%, and the mass percentage of Mg element is 3% - 7%.

[0007] Preferably, the median particle size D50 of the silicon carbide particles is 80μm - 85μm, and the packing density of the silicon carbide particle aggregates is 50% - 60%.

[0008] Preferably, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 1% - 3%.

[0009] The method for large-scale preparation of the above silicon carbide reinforced aluminum matrix composite material by pressureless infiltration includes the following steps:

[0010] S1. Clean and dry the silicon carbide particles, place the cleaned silicon carbide particles in a graphite crucible to form an aggregate, and flatten the upper surface of the aggregate;

[0011] S2. Melt the Al-Si-Mg aluminum alloy to obtain an Al-Si-Mg aluminum alloy ingot;

[0012] S3. Cut the Al-Si-Mg aluminum alloy ingot into Al-Si-Mg aluminum alloy blocks, and place the Al-Si-Mg aluminum alloy blocks on the upper surface of the silicon carbide particle aggregate;

[0013] S4. Heat and keep the graphite crucible and its contents in a nitrogen atmosphere, and after cooling to room temperature, obtain the silicon carbide reinforced aluminum matrix composite material.

[0014] Preferably, it further includes:

[0015] S5. Measure the density of the silicon carbide reinforced aluminum matrix composite material and the infiltration rate corresponding to the preparation process, and select the aluminum alloy corresponding to the silicon carbide reinforced aluminum matrix composite material with the highest infiltration rate and the highest density as the Al-Si-Mg aluminum alloy matrix;

[0016] S6. Melt the Al-Si-Mg aluminum alloy matrix, and add Ti element according to the mass ratio therein to obtain an Al-Si-Mg-Ti aluminum alloy ingot;

[0017] S7. Cut the Al-Si-Mg-Ti aluminum alloy ingot into Al-Si-Mg-Ti aluminum alloy blocks, and place the Al-Si-Mg-Ti aluminum alloy blocks on the upper surface of the silicon carbide particle aggregate;

[0018] S8. Heat and hold the graphite crucible and its contents in a nitrogen atmosphere, and after cooling to room temperature, a silicon carbide reinforced aluminum matrix composite material is obtained.

[0019] Preferably, in S3, the mass of the Al-Si-Mg aluminum alloy block is 110% - 120% of the theoretical mass calculated based on the volume of the stacked body and the porosity of the stacked body.

[0020] Preferably, in S4, the heating temperature is 850°C - 950°C, and the holding time is 7 hours - 10 hours.

[0021] Preferably, in S6, the mass percentage of Ti element is 1% - 3%.

[0022] Preferably, in S7, the mass of the Al-Si-Mg-Ti aluminum alloy block is 110% - 120% of the theoretical mass calculated based on the volume of the stacked body and the porosity of the stacked body.

[0023] Preferably, in S8, the heating temperature is 850°C - 950°C, and the holding time is 7 hours - 10 hours.

[0024] The advantages and positive effects of the silicon carbide reinforced aluminum matrix composite material and the large-scale pressureless infiltration preparation method thereof according to the present invention are as follows:

[0025] 1. In the present invention, the contents of Si element and Mg element are increased in the Al-Si-Mg ternary aluminum alloy, and a higher pressureless infiltration rate is obtained on the premise of ensuring a higher density of the aluminum matrix composite material.

[0026] 2. In the present invention, Ti element is added to the Al-Si-Mg ternary aluminum alloy screened with a higher density and infiltration rate. The Ti element further improves the infiltration rate of the aluminum alloy matrix, effectively shortens the holding time at high temperature in the large-scale pressureless infiltration preparation method of the composite material, inhibits the harmful interfacial chemical reaction between molten aluminum and silicon carbide, and avoids the problems of deliquescence and pulverization of the composite material caused by the harmful interfacial chemical reaction product - Al4C3, which is beneficial to improving the strength of the composite material.

[0027] 3. The silicon carbide reinforced aluminum matrix composite material prepared by using the composite material and the large-scale preparation method described in the present invention can achieve the high-quality preparation of a billet with an ultra-large projected area of 3 square meters and a thickness of 170 millimeters (as shown in Figure 1 ), and at the same time, the strength of the composite material is increased by about 11%, broadening the application scenarios of the silicon carbide reinforced aluminum matrix composite material.

[0028] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0029] Figure 1 The physical diagram of the large-sized ingot of the silicon carbide reinforced aluminum matrix composite prepared in the embodiment of the present invention;

[0030] Figure 2 The diameter measurement diagram of the large-sized cylindrical ingot of the silicon carbide reinforced aluminum matrix composite prepared in the embodiment of the present invention;

[0031] Figure 3 The thickness measurement diagram of the large-sized ingot of the silicon carbide reinforced aluminum matrix composite prepared in the embodiment of the present invention;

[0032] Figure 4 The weighing diagram of the large-sized ingot of the silicon carbide reinforced aluminum matrix composite prepared in the embodiment of the present invention. Specific embodiments

[0033] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0034] The following will describe in detail the embodiments of the present invention with reference to the accompanying drawings.

[0035] Example 1

[0036] A silicon carbide reinforced aluminum matrix composite, comprising an aluminum matrix, and silicon carbide reinforcements are distributed inside the aluminum matrix. The silicon carbide reinforcements are silicon carbide particle aggregates, the aluminum matrix is an Al-Si-Mg aluminum alloy, and the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 12% and the mass percentage of Mg element is 3%.

[0037] The silicon carbide particles are commercially available abrasive-grade green silicon carbide particles. The median particle size D50 of the silicon carbide particles is 82 μm, and the packing density of the silicon carbide particle aggregates is 55%.

[0038] A method for the large-scale preparation of the silicon carbide reinforced aluminum matrix composite by pressureless infiltration, comprising the following steps:

[0039] S1. Clean and then dry the silicon carbide particles, place the cleaned silicon carbide particles in a graphite crucible to form an aggregate, and flatten the upper surface of the aggregate with a glass plate. The method of stacking the silicon carbide particles can adopt the existing pressing or vibrating method to make the silicon carbide particles closely packed, and no connection is generated between the silicon carbide particles.

[0040] S2. Melt the Al-Si-Mg aluminum alloy to obtain an Al-Si-Mg aluminum alloy ingot.

[0041] S3. Cut the Al-Si-Mg aluminum alloy ingot into Al-Si-Mg aluminum alloy blocks, and place the Al-Si-Mg aluminum alloy blocks on the upper surface of the silicon carbide particle stack.

[0042] The mass of the Al-Si-Mg aluminum alloy block is 110%-120% of the theoretical mass calculated based on the volume of the stack and the porosity (45%) of the stack. This enables the Al-Si-Mg aluminum alloy to fully wrap the silicon carbide particle stack inside the aluminum alloy.

[0043] S4. Put the graphite crucible, the silicon carbide particle stack inside it, and the Al-Si-Mg aluminum alloy blocks into a heating furnace, and heat and keep warm under a nitrogen atmosphere. The heating temperature is 900 °C, and the holding time is 8 hours.

[0044] After cooling to room temperature, a silicon carbide reinforced aluminum matrix composite is obtained.

[0045] Example 2

[0046] The distinguishing technical feature of this example from Example 1 is that the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 14%, and the mass percentage of Mg element is 3%.

[0047] Example 3

[0048] The distinguishing technical feature of this example from Example 1 is that the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 16%, and the mass percentage of Mg element is 3%.

[0049] Example 4

[0050] The distinguishing technical feature of this example from Example 1 is that the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 12%, and the mass percentage of Mg element is 5%.

[0051] Example 5

[0052] The distinguishing technical feature of this example from Example 1 is that the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 14%, and the mass percentage of Mg element is 5%.

[0053] Example 6

[0054] The distinguishing technical feature of this example from Example 1 is that the mass percentage of Si element in the Al-Si-Mg aluminum alloy is 16%, and the mass percentage of Mg element is 5%.

[0055] Example 7

[0056] The distinguishing technical features of this embodiment from Embodiment 1 are as follows: in the Al-Si-Mg aluminum alloy, the mass percentage of Si element is 12% and the mass percentage of Mg element is 7%.

[0057] Embodiment 8

[0058] The distinguishing technical features of this embodiment from Embodiment 1 are as follows: in the Al-Si-Mg aluminum alloy, the mass percentage of Si element is 14% and the mass percentage of Mg element is 7%.

[0059] Embodiment 9

[0060] The distinguishing technical features of this embodiment from Embodiment 1 are as follows: in the Al-Si-Mg aluminum alloy, the mass percentage of Si element is 16% and the mass percentage of Mg element is 7%.

[0061] The density of the silicon carbide reinforced aluminum matrix composites prepared in Embodiments 1-9 and the corresponding infiltration distance under the conditions of 900 °C × 8 h were detected, and the results are shown in Table 1.

[0062] Table 1 Density and infiltration distance of the composites prepared in Embodiments 1-9

[0063]

[0064]

[0065] It can be seen from Table 1 that under the same holding temperature and holding time conditions, the Al-7Mg-16Si matrix alloy composition used in Embodiment 9 corresponds to the longest infiltration distance and the highest density of the composite material.

[0066] By increasing the contents of Si element and Mg element in the Al-Si-Mg ternary aluminum alloy, a higher pressureless infiltration rate can be obtained on the premise of ensuring a higher density of the aluminum matrix composite. The specific mechanism is as follows:

[0067] (1) The Si element reduces the surface tension and increases the infiltration rate. The Si atom has a relatively large radius. In the alloy liquid, it will change the arrangement and interaction between atoms, weaken the inward pulling force of the surface layer atoms, thereby reducing the surface tension. During the pressureless infiltration process, the tiny pores of the silicon carbide particles are similar to capillaries. The reduction of the surface tension of the alloy liquid makes it easier to fill these pores, thereby increasing the infiltration rate. In addition, Si is enriched at the interface between the alloy liquid and the reinforcement, changing the electronic structure of the interface and enhancing the interaction between the two. Coupled with the mechanical embedding effect of the Si phase at the interface, the interface bonding condition is further improved.

[0068] (2) Si element balances the interfacial reaction and inhibits the formation of Al3C4. During the process of the molten alloy liquid infiltrating into the SiC particle stack, there is a thermodynamic tendency for interfacial chemical reactions to occur (the reaction equation is 3SiC + 4Al = Al4C3 + 3Si). According to the principle of chemical equilibrium, when the Si content in the molten aluminum liquid increases, the reaction equilibrium will shift in the direction of inhibiting the forward reaction, that is, the reaction rate of the forward interfacial reaction is reduced, which can effectively inhibit the formation of Al4C3. At the same time, in a high-Si environment, the dissolution activity of SiC can be reduced, further hindering the formation of Al4C3.

[0069] (3) Mg element destroys the oxide film on the surface of the Al liquid and reduces the surface free energy of the system. When the aluminum alloy is in a molten state, according to Gibbs adsorption theory, Mg will diffuse and accumulate on the surface of the alloy liquid. Mg has a low vapor pressure. During the pressureless infiltration process, due to the high experimental temperature, Mg is very easy to form Mg vapor and volatilize from the molten metal solution. The saturated vapor pressure produced by Mg is relatively high and can penetrate and destroy the Al2O3 layer, making the Al melt directly contact with SiC, thus eliminating the hindrance of the Al2O3 film to the infiltration behavior of the SiC / Al system and improving the wettability between the aluminum liquid and SiC and the interfacial combination between the two. At the same time, the presence of more Mg elements significantly improves the fluidity of the molten Al by reducing the surface free energy of the system and the surface tension of the melt, reduces the viscosity of the aluminum liquid, and is easy to spread rapidly on the surface of the SiC particles, thereby increasing the infiltration rate.

[0070] (4) The combined reaction of Mg, nitrogen, and aluminum liquid improves the wettability. In a nitrogen atmosphere, the volatilized Mg reacts with N2 to form Mg3N2, which covers the surface of the SiC particles. Subsequently, Mg3N2 further undergoes an exothermic reaction with the Al melt to form AlN, releasing heat and reducing the liquid-gas surface energy γ lv and the melt viscosity and improving the wettability.

[0071] Example 10

[0072] The difference between this example and Example 9 is that in this example, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 1%.

[0073] The method for large-scale preparation of pressureless infiltration of silicon carbide-reinforced aluminum matrix composites includes the following steps:

[0074] S6. Melting the Al-16Si-7Mg aluminum alloy matrix and adding Ti element according to the mass ratio therein to obtain an Al-Si-Mg-Ti aluminum alloy ingot.

[0075] S7. Cut the Al-Si-Mg-Ti aluminum alloy ingot into Al-Si-Mg-Ti aluminum alloy blocks, and place the Al-Si-Mg-Ti aluminum alloy blocks on the upper surface of the silicon carbide particle accumulation.

[0076] The mass of the Al-Si-Mg-Ti aluminum alloy block is 110%-120% of the theoretical mass calculated based on the volume of the accumulation and the porosity (45%) of the accumulation.

[0077] S8. Heat and keep warm the graphite crucible and its contents under a nitrogen atmosphere. After cooling to room temperature, a silicon carbide-reinforced aluminum matrix composite is obtained.

[0078] The heating temperature is 900 °C, and the holding time is 8 hours.

[0079] After cooling to room temperature, a silicon carbide-reinforced aluminum matrix composite is obtained.

[0080] Example 11

[0081] The difference between this example and Example 10 is that in this example, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 1.5%.

[0082] Example 12

[0083] The difference between this example and Example 10 is that in this example, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 2%.

[0084] Example 13

[0085] The difference between this example and Example 10 is that in this example, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 2.5%.

[0086] Example 14

[0087] The difference between this example and Example 10 is that in this example, the Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 3%.

[0088] Detect the bending strength of the silicon carbide-reinforced aluminum matrix composite billets prepared in Examples 10-14 and the penetration distance under the conditions of 900 °C × 8 h. The results are shown in Table 2.

[0089] Table 2 Bending strength and penetration distance of the composites prepared in Examples 10-14

[0090]

[0091] As can be seen from Table 2, after adding Ti element to Al-16Si-7Mg aluminum alloy, the infiltration penetration distance can be further increased, and the bending strength of the composite material is also improved. When the mass percentage of Ti element is 1.5%, the maximum infiltration distance of the aluminum matrix is 170 mm, and the infiltration rate is increased by about 30%. When the mass percentage of Ti element is 1.5%, the maximum bending strength of the silicon carbide reinforced aluminum matrix composite material is 432 MPa, and the bending strength is increased by about 11%.

[0092] Ti can be used as a grain refiner in Al-Si-Mg alloy. It reacts with Al to form compounds such as TiAl3. These compounds can serve as heterogeneous nucleation cores, increasing the number of nucleation and refining the alloy grains. The refined grains shorten the atomic diffusion distance. During the infiltration process, atoms in the alloy liquid are more likely to diffuse into the pores of the reinforcement, thus increasing the infiltration rate. The fine grain structure also enhances the strength and toughness of the alloy.

[0093] Ti element can reduce the interfacial energy between the alloy liquid and the reinforcement. Ti will segregate at the interface, changing the structure and properties of the interface and reducing the interfacial energy. The lower interfacial energy makes the spreading and infiltration of the alloy liquid on the surface of the reinforcement easier, which is beneficial for the alloy liquid to fill the pores, thereby increasing the infiltration rate.

[0094] Ti element can improve the fluidity of Al-Si-Mg alloy, reduce its viscosity, and enhance the fluidity of the alloy liquid. The alloy liquid with good fluidity is more likely to flow in the pores of the reinforcement during pressureless infiltration, improving the infiltration efficiency and uniformity.

[0095] The physical diagram of the aluminum matrix composite material prepared by using the silicon carbide reinforced aluminum matrix composite material and its large-scale preparation method of pressureless infiltration described in the present invention is as Figures 1-4 shown. The size (diameter) of the prepared silicon carbide reinforced aluminum matrix composite ingot reaches more than 2000 mm, and the thickness reaches more than 170 mm, realizing the preparation of large-size ingots of silicon carbide reinforced aluminum matrix composite materials.

[0096] Therefore, by using the silicon carbide reinforced aluminum matrix composite material and its large-scale preparation method of pressureless infiltration described in the present invention, through adjusting the composition of Al-Si-Mg aluminum alloy and adding Ti element, the preparation of large-size ingots of silicon carbide reinforced aluminum matrix composite materials is realized, and the bending strength of the composite material is significantly improved.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements do not enable the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A silicon carbide reinforced aluminum matrix composite material, characterized in that: It includes an aluminum matrix, in which silicon carbide reinforcements are distributed. The silicon carbide reinforcements are silicon carbide particle aggregates, and the aluminum matrix is an Al-Si-Mg aluminum alloy. In the Al-Si-Mg aluminum alloy, the mass percentage of Si element is 12% - 16%, and the mass percentage of Mg element is 3% - 7%.

2. The silicon carbide reinforced aluminum matrix composite material according to claim 1, wherein: The median particle size D50 of the silicon carbide particles is 80μm - 85μm, and the packing density of the silicon carbide particle aggregates is 50% - 60%.

3. The silicon carbide reinforced aluminum matrix composite according to claim 2, wherein: The Al-Si-Mg aluminum alloy contains Ti element, and the mass percentage of Ti element is 1% - 3%.

4. A method for large-scale preparation of silicon carbide reinforced aluminum matrix composite by pressureless infiltration as claimed in claim 3, characterized in that, It includes the following steps: S1. Clean and dry the silicon carbide particles, place the cleaned silicon carbide particles in a graphite crucible to form an aggregate, and flatten the upper surface of the aggregate; S2. Melt the Al-Si-Mg aluminum alloy to obtain an Al-Si-Mg aluminum alloy ingot; S3. Cut the Al-Si-Mg aluminum alloy ingot into Al-Si-Mg aluminum alloy blocks, and place the Al-Si-Mg aluminum alloy blocks on the upper surface of the silicon carbide particle aggregate; S4. Heat and keep warm the graphite crucible and its contents in a nitrogen atmosphere, and after cooling to room temperature, obtain a silicon carbide reinforced aluminum matrix composite material.

5. The silicon carbide reinforced aluminum matrix composite according to claim 4, wherein It also includes: S5. Measure the density of the silicon carbide reinforced aluminum matrix composite material and the infiltration rate corresponding to the preparation process, and select the aluminum alloy corresponding to the silicon carbide reinforced aluminum matrix composite material with the highest infiltration rate and the highest density as the Al-Si-Mg aluminum alloy matrix; S6. Melt the Al-Si-Mg aluminum alloy matrix, and add Ti element according to the mass ratio to obtain an Al-Si-Mg-Ti aluminum alloy ingot; S7. Cut the Al-Si-Mg-Ti aluminum alloy ingot into Al-Si-Mg-Ti aluminum alloy blocks, and place the Al-Si-Mg-Ti aluminum alloy blocks on the upper surface of the silicon carbide particle aggregate; S8. Heat and keep warm the graphite crucible and its contents in a nitrogen atmosphere, and after cooling to room temperature, obtain a silicon carbide reinforced aluminum matrix composite material.

6. A method for large-scale preparation of silicon carbide reinforced aluminum matrix composite by pressureless infiltration, characterized in that: In S3, the mass of the Al-Si-Mg aluminum alloy block is 110% - 120% of the theoretical mass calculated according to the volume of the aggregate and the porosity of the aggregate.

7. A method for large-scale preparation of silicon carbide reinforced aluminum matrix composite by pressureless infiltration, characterized in that: In S4, the heating temperature is 850°C - 950°C, and the holding time is 7 hours - 10 hours.

8. The large-scale pressureless infiltration preparation method of a silicon carbide reinforced aluminum matrix composite according to claim 5, characterized in that: In S6, the mass percentage of Ti element is 1% - 3%.

9. The large-scale pressureless infiltration preparation method of the silicon carbide reinforced aluminum matrix composite material according to claim 5, characterized in that: In S7, the mass of the Al-Si-Mg-Ti aluminum alloy block is 110% - 120% of the theoretical mass calculated according to the volume of the aggregate and the porosity of the aggregate.

10. A method for the large-scale preparation of a silicon carbide reinforced aluminum matrix composite by pressureless infiltration according to claim 5, characterized in that: In S8, the heating temperature is 850°C - 950°C, and the holding time is 7 hours - 10 hours.

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