High-strength and tough Al-Si alloy and preparation method thereof

Abstract

The present invention provides a high-strength and toughness Al-Si alloy and a preparation method thereof. The high-strength and toughness Al-Si alloy comprises an Al matrix, Si, Al-SiC particles and C-TiB2 particles. Based on 100wt.% of the high-strength and toughness Al-Si alloy, the content of Si is 8.5wt.%-12wt.%, the Al-SiC particles have the crystal structure of SiC, but are doped with Al atoms; the C-TiB2 particles are C-doped TiB2 particles, having the crystal structure of TiB2 and doped with trace C elements. The high-strength and toughness Al-Si alloy according to the present invention effectively improves strength and toughness through in-situ generated Al-SiC particles and C-TiB2 particles.

Description

Technical Field

[0001] The present invention relates to the field of metal materials, and in particular to a high-strength and toughness Al-Si alloy and a preparation method thereof. Background Art

[0002] With the increasingly stringent requirements for energy conservation and emission reduction and the rapid development of new energy vehicles, the process of automobile lightweighting is unstoppable. As far as fuel vehicles are concerned, studies have shown that for every 100kg reduction in vehicle mass, fuel consumption per 100 kilometers can be reduced by 0.3L-0.5L. As for new energy vehicles, the change in powertrain caused by the addition of the three-electric system makes the vehicle at least 200-300 kilograms heavier than fuel vehicles, so lightweighting is of great significance to improving energy efficiency, reducing energy consumption and increasing cruising range of new energy vehicles. Aluminum alloys have become the preferred material for automobile lightweighting due to their excellent specific strength, plastic toughness, casting performance, and processing and forming performance.

[0003] The chassis subframe is an important structural safety part in the car. The subframe connects and fixes the suspension system, steering system, engine and other assembly parts. Therefore, it has high requirements for its strength, rigidity, dimensional accuracy and other performance. At present, the production process mostly adopts the integrated low-pressure casting process to manufacture automobile subframes, which can not only reduce the weight of the subframe and simplify the manufacturing process, but also the integrated structure can enhance the load-bearing performance of the whole vehicle, improve the handling stability, and enhance the safety and comfort of riding. The compact structure of the integrated low-pressure casting makes the mold structure, sand core shape and pouring system more complicated, which is easy to cause defects such as air entrainment, shrinkage and shrinkage, and ultimately make the product quality substandard. Summary of the invention

[0004] The object of the present invention is to provide a high-strength and toughness Al-Si alloy and a preparation method thereof.

[0005] According to one aspect of the present invention, a high-strength and tough Al-Si alloy is provided, comprising an Al matrix, Si, in-situ generated Al-SiC particles and C-TiB 2 The particles are based on 100wt.% of the high-strength and tough Al-Si alloy, the Si content is 8.5wt.%-12wt.%, the Al-SiC particles are Al-doped SiC particles, have a SiC crystal structure and are doped with a trace amount of Al, and the C-TiB 2 The particles are C-doped TiB 2 Particles, with TiB 2 The crystal structure is doped with trace amounts of C elements.

[0006] Optionally, based on 100 wt.% of the Al-SiC particles, the Al doping amount is greater than or equal to 0.05 wt.% and less than or equal to 8 wt.%, based on 100 wt.% of the C-TiB 2Particles, C doping amount is greater than or equal to 0.02wt.% and less than or equal to 1.8wt.%.

[0007] Optionally, based on 100wt.% of the high-strength and tough Al-Si alloy, the content of the Al-SiC particles is 0.03wt.%-2wt.%, and the C-TiB 2 The content of the particles is 0.028wt.%-1.7wt.%.

[0008] Optionally, based on 100wt.% of the high-strength and toughness Al-Si alloy, the content of C is 0.01wt.%-0.6wt.%, and the content of B is 0.009wt.%-0.54wt.%.

[0009] Optionally, the high-strength and toughness Al-Si alloy further comprises at least one of Ti, Mg, Zn, RE, Sr, Fe, Cr and Mn. Based on 100wt.% of the high-strength and toughness Al-Si alloy, the content of Ti is 0.08wt.%-1.3wt.%, the content of Mg is 0.1wt.%-1.0wt.%, the content of Zn is less than or equal to 5.0wt.%, the content of RE is 0.01wt.%-0.3wt.%, the content of Sr is 0.01wt.%-0.05wt.%, the content of Fe is less than or equal to 0.3wt.%, the content of Cr is 0.01wt.%-0.15wt.%, the content of Mn is 0.05wt.%-0.7wt.%, and the total content of other impurity elements in the high-strength and toughness Al-Si alloy does not exceed 0.5wt.%.

[0010] According to another aspect of the present invention, a method for preparing a high-strength and tough Al-Si alloy is provided, the method comprising: adding a first portion of an aluminum source and an Al-Al 3 BC seed alloy is heated to 760℃-880℃, and the Al-Al 3 BC seed alloy includes Al 3 BC particles, the Al-Al 3 The addition amount of BC seed alloy is 0.2wt.%-30.0wt.% of the total weight of the high-strength and toughness Al-Si alloy; pure silicon and Al-Ti alloy are added to the melt to ensure that the mass percentage of Si in the melt is 22.0wt.%-27.0wt.%, the melt temperature is adjusted to 780℃-830℃ and reacted for 15min-45min; after the reaction is completed, the melt temperature is maintained at 780℃-830℃, and the second part of aluminum source is added to the melt to ensure that the Si content in the high-strength and toughness Al-Si alloy is 8.5wt.%-12wt.%.

[0011] Optionally, based on 100wt.% of the Al-Al 3 BC seed alloy, the Al 3 The content of BC particles is 0.3wt.%-20.0wt.%.

[0012] Optionally, the preparation method further includes: after the reaction is completed, maintaining the melt temperature at 780°C-830°C, adding Al-Fe alloy, Al-Cr alloy, and Al-Mn alloy to the melt; adjusting the melt temperature to 720°C-780°C, adding pure magnesium, pure zinc, Al-RE alloy, and Al-Sr alloy and keeping warm for 15min-30min.

[0013] Optionally, the preparation method further comprises: after adding pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy and keeping warm for 15-30 minutes, refining the melt at a temperature of 730-760°C for 10-30 minutes, and then pouring to obtain the alloy material or casting.

[0014] Optionally, the cast alloy material or casting is quenched at 400°C-500°C and aged at 155°C-175°C for 1h-10h, or the cast alloy material or casting is solution treated at 510°C-530°C for 3h-8h and quenched, and then aged at 155°C-175°C for 1h-10h.

[0015] The high-strength and tough Al-Si alloy according to the present invention comprises in-situ generated Al-SiC particles and C-TiB 2 Particles can refine the grain size and improve the grain morphology, improve the flowability, forming performance of the alloy melt and the surface quality and consistency of the casting, improve the density, reduce defects such as shrinkage and shrinkage holes, and can also effectively cooperate with eutectic Si to build a strengthening structure, and can regulate and promote the efficient precipitation of the aging phase during the heat treatment process, thereby improving the one-piece die-casting formability and toughness of the material.

[0016] According to the present invention, since Al is doped into SiC particles, the mass fraction of SiC particles can be increased on the one hand, and the size of SiC particles can be further reduced on the other hand, thereby helping to improve the strengthening and toughening effect of SiC particles.

[0017] According to the present invention, by using Al 3 In-situ generation of Al-SiC particles and C-TiB by instability of BC seeds in Al-Si-Ti melt 2 The particles have low raw material cost, simple process, green environmental protection and high industrialization potential. The high-strength and tough Al-Si alloy prepared thereby has high strength and toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings.

[0019] Figure 1 1 is a microstructure diagram and a line scanning analysis diagram of a high-strength and tough Al-Si alloy according to an embodiment of the present invention.

[0020] Figure 2 1 is a microstructure diagram and a line scanning analysis diagram of a high-strength and tough Al-Si alloy according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] Hereinafter, embodiments of the present disclosure will be described as follows with reference to the accompanying drawings.

[0024] However, the present disclosure may be exemplified in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0025] It should be understood that when the terms “include” and / or “comprises” are used in the specification, they list the presence of stated materials and / or components, but do not exclude the presence or addition of one or more other materials and / or components.

[0026] High strength and toughness Al-Si alloy

[0027] The high-strength and toughness Al-Si alloy according to an embodiment of the present invention may include an Al matrix and Si, wherein the content of Si may be 8.5 wt. %-12 wt. % based on 100 wt. % of the high-strength and toughness Al-Si alloy.

[0028] The high-strength and toughness Al-Si alloy according to the embodiment of the present invention may also include in-situ generated Al-SiC particles and C-TiB 2The Al-SiC particles are Al-doped SiC particles, which have a SiC crystal structure and are doped with a trace amount of Al. 2 The particles are C-doped TiB 2 Particles, with TiB 2 The crystal structure is doped with trace amounts of C elements.

[0029] Al-SiC particles can effectively cooperate with eutectic Si to build a strengthening structure. Because the particles are synthesized in situ, the interface between them and the aluminum matrix is ​​clean and well-bonded, which is conducive to fully exerting the load transfer during the force process and improving the strength and toughness of the material. 2 The synergistic effect of the particles can regulate and promote the efficient precipitation of the aging strengthening phase β'' during heat treatment.

[0030] C-TiB 2 The particles can refine the α-Al grain size and improve the grain morphology, improve the flow properties, forming properties of the alloy melt and the surface quality and consistency of the casting, increase the density, and reduce defects such as shrinkage and shrinkage.

[0031] Figure 1 1 is a microstructure diagram and line scanning analysis diagram of a high-strength and tough Al-Si alloy according to an embodiment of the present invention. Figure 1 As shown, the white particles are Al-SiC particles ( Figure 1 The morphology of the composite is nearly circular.

[0032] According to the embodiment of the present invention, since SiC particles are doped with Al, the mass fraction of SiC particles can be increased on the one hand, and the size of SiC particles can be further reduced on the other hand, thereby helping to improve the strengthening and toughening effect of SiC particles.

[0033] According to an embodiment of the present invention, based on 100wt.% of Al-SiC particles, the Al doping amount may be greater than or equal to 0.05wt.% and less than or equal to 8wt.%. If the Al doping amount is less than 0.05wt.% based on 100wt.% of Al-SiC particles, the toughening effect may be insufficient. If the Al doping amount exceeds 8wt.% based on 100wt.% of Al-SiC particles, the strength of the SiC particles themselves may be affected. As an example, based on 100wt.% of Al-SiC particles, the Al doping amount may be greater than or equal to 0.5wt.% and less than or equal to 6wt.%, greater than or equal to 1wt.% and less than or equal to 5wt.%, or greater than or equal to 2wt.% and less than or equal to 4wt.%. Figure 1 EDS point analysis of the white particles in the graphene shows that the Al doping amount is 7.85 wt. % based on 100 wt. % Al-SiC particles.

[0034] According to an embodiment of the present invention, based on 100wt.% of the high-strength and tough Al-Si alloy, the content of Al-SiC particles is 0.03wt.%-2wt.%. If the content of Al-SiC particles is less than 0.03wt.% based on 100wt.% of the high-strength and tough Al-Si alloy, the strengthening and toughening effect of the Al-SiC particles may be insufficient. If the content of Al-SiC particles is greater than 2wt.% based on 100wt.% of the high-strength and tough Al-Si alloy, the content of other effective elements will be reduced, which may be detrimental to the improvement of comprehensive performance. As an example, based on 100wt.% of the high-strength and tough Al-Si alloy, the content of Al-SiC particles is 0.08wt.%-1.5wt.%, 0.2wt.%-1.4wt.%, or 0.8wt.%-1.2wt.%.

[0035] Figure 2 1 is a microstructure diagram and line scanning analysis diagram of a high-strength and tough Al-Si alloy according to an embodiment of the present invention. Figure 2 As shown, the white particles are C-TiB 2 particle( Figure 2 Marked as C-TiB 2 ).

[0036] According to an embodiment of the present invention, based on 100wt.% of C-TiB 2 The C doping amount is greater than or equal to 0.02wt.% and less than or equal to 1.8wt.% to improve the refinement effect and refinement stability of α-Al grains. As an example, based on 100wt.% C-TiB 2 Particles, a C doping amount is greater than or equal to 0.08wt.% and less than or equal to 1.5wt.%, a C doping amount is greater than or equal to 0.2wt.% and less than or equal to 1.3wt.%, a C doping amount is greater than or equal to 0.5wt.% and less than or equal to 1.2wt.%, or a C doping amount is greater than or equal to 0.7wt.% and less than or equal to 1.0wt.%.

[0037] According to an embodiment of the present invention, based on 100wt.% of a high-strength and tough Al-Si alloy, C-TiB 2 The content of the particles is 0.028wt.%-1.7wt.% to improve the refinement effect of α-Al grains. As an example, based on 100wt.% of high-strength and tough Al-Si alloy, C-TiB 2 The content of the particles is 0.06wt.%-1.6wt.%, 0.1wt.%-1.4wt.%, 0.3wt.%-1.2wt.%, or 0.6wt.%-1.0wt.%.

[0038] According to an embodiment of the present invention, based on 100 wt.% of the high-strength and toughness Al-Si alloy, the content of C may be 0.01 wt.%-0.6 wt.%, and the content of B may be 0.009 wt.%-0.54 wt.%.

[0039] The high-strength and toughness Al-Si alloy according to the embodiment of the present invention may further include at least one of Ti, Mg, Zn, RE, Sr, Fe, Cr and Mn.

[0040] Zn has a high solubility in Al and can be dissolved in the aluminum matrix after casting and quenching, playing a role in solid solution strengthening. Mg and Si elements precipitate nano-strengthening phase β'' during the heat treatment aging process, which is the main strengthening phase. Cr and Mn can jointly transform the iron-rich phase from needle-like to Chinese character-like, and can also improve mold sticking. Sr and RE can jointly transform eutectic Si from coarse plate-like to coral-like. The type of RE is not specifically limited, for example, it can be at least one of La and Ce, or it can be a mixed rare earth.

[0041] According to an embodiment of the present invention, based on 100wt.% of the high-strength and toughness Al-Si alloy, the Ti content may be 0.08wt.%-1.3wt.%, the Mg content may be 0.1wt.%-1.0wt.%, the Zn content may be less than or equal to 5.0wt.%, the RE content may be 0.01wt.%-0.3wt.%, the Sr content may be 0.01wt.%-0.05wt.%, the Fe content may be less than or equal to 0.3wt.%, the Cr content may be 0.01wt.%-0.15wt.%, and the Mn content may be 0.05wt.%-0.7wt.%.

[0042] The high-strength and tough Al-Si alloy according to an embodiment of the present invention includes in-situ generated Al-SiC particles and C-TiB 2 Particles can refine the grain size and improve the grain morphology, improve the flowability, forming performance of the alloy melt and the surface quality and consistency of the casting, improve the density, reduce defects such as shrinkage and shrinkage holes, and can also effectively cooperate with eutectic Si to build a strengthening structure, and can regulate and promote the efficient precipitation of the aging phase during the heat treatment process, thereby improving the one-piece die-casting formability and toughness of the material.

[0043] Preparation method of high-strength and tough Al-Si alloy

[0044] Hereinafter, a method for preparing a high-strength and tough Al-Si alloy according to an embodiment of the present invention will be described.

[0045] The method for preparing a high-strength and tough Al-Si alloy according to an embodiment of the present invention may include: adding a first portion of an aluminum source and an Al-Al3 BC seed alloy, heated to 760℃-880℃, Al-Al 3 BC seed alloy includes Al 3 BC particles, Al-Al 3 The addition amount of BC seed alloy is 0.2wt.%-30.0wt.% of the total weight of the high-strength and tough Al-Si alloy (S1); pure silicon and Al-Ti alloy are added to the melt to ensure that the mass percentage of Si in the melt is 22.0wt.%-27.0wt.%, and the melt temperature is adjusted to 780℃-830℃ and reacted for 15min-45min (S2); after the reaction is completed, the melt temperature is maintained at 780℃-830℃, and the second part of aluminum source is added to the melt to ensure that the Si content in the high-strength and tough Al-Si alloy is 8.5wt.%-12wt.% (S3).

[0046] In step S1, an aluminum source and an Al-Al 3 BC seed alloy, as an example, the aluminum source can be pure aluminum. 3 The BC seed alloy is added into the melting furnace and then heated to melt at 760°C-880°C.

[0047] Al-Al 3 BC seed alloy includes Al 3 BC particles, Al 3 BC particles are used as reaction raw materials to react with the subsequently added Si and Ti elements to generate Al-SiC particles and C-TiB 2 particle.

[0048] Al-Al 3 The addition amount of BC seed alloy is 0.2wt.%-30.0wt.% of the total weight of the high-strength and tough Al-Si alloy. As an example, based on 100wt.% Al-Al 3 BC seed alloy, Al 3 The content of BC particles is 0.3wt.%-20.0wt.%.

[0049] In step S2, pure silicon and Al-Ti alloy are added to the melt to ensure that the mass percentage of Si in the melt is 22.0wt.%-27.0wt.%, and the melt temperature is adjusted to 780℃-830℃ and reacted for 15min-45min. 3 Al in BC seed alloy 3 BC particles react with Ti and Si to generate Al-SiC particles and C-TiB 2 particle.

[0050] According to an embodiment of the present invention, ensuring that the mass percentage of Si in the melt is 22.0wt.%-27.0wt.% is to provide the necessary Si concentration for the generation of Al-SiC particles. If the Si content in the melt exceeds the above content range, the above two particles may not be generated at the same time, or the amount of generated particles is small.

[0051] In step S3, after the reaction is completed, the melt temperature is maintained at 780°C-830°C, a second portion of aluminum source (eg, pure aluminum) is added to the melt, and the Si concentration is adjusted to ensure that the Si content in the high-strength and tough Al-Si alloy is 8.5wt.%-12wt.%.

[0052] The method for preparing a high-strength and tough Al-Si alloy according to an embodiment of the present invention may further include, after the reaction is completed, maintaining the melt temperature at 780° C. to 830° C., and adding Al-Fe alloy, Al-Cr alloy and Al-Mn alloy to the melt. The operation of adding Al-Fe alloy, Al-Cr alloy and Al-Mn alloy to the melt may be performed in step S3, or may be performed after the aluminum source is dissolved, and the present invention does not impose any specific restrictions on this.

[0053] The preparation method of the high-strength and toughness Al-Si alloy according to an embodiment of the present invention may also include: after the Al-Fe alloy, Al-Cr alloy and Al-Mn alloy are dissolved, adjusting the melt temperature to 720°C-780°C, adding pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy and keeping warm for 15min-30min.

[0054] Al-Fe alloy, Al-Cr alloy, Al-Mn alloy are added at 780℃-830℃ because they are difficult to dissolve and require higher temperatures. The melt temperature is then adjusted to 720℃-780℃ to add pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy because these materials are easily burned at high temperatures, so the temperature is appropriately lowered.

[0055] The preparation method of the high-strength and toughness Al-Si alloy according to an embodiment of the present invention may also include: after adding pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy and keeping warm for 15min-30min, refining the melt at a temperature of 730℃-760℃ for 10min-30min, and then pouring to obtain the alloy material or casting.

[0056] The method for preparing the high-strength and toughness Al-Si alloy according to the embodiment of the present invention may further include the step of heat treating the alloy material or the casting.

[0057] As an example, the step of heat treating the alloy material or casting may include: quenching the cast alloy material or casting at 400°C-500°C, and aging at 155°C-175°C for 1h-10h. If the high-strength and tough Al-Si alloy according to the present invention is used to manufacture automobile subframes, because the subframe is a thin-walled part with a wall thickness of usually 3-8mm, if conventional solution quenching heat treatment is performed, the subframe will be deformed due to internal stress, which will seriously affect its dimensional accuracy as an important connecting part and even become scrap. Therefore, choosing to cast and quench at 400°C-500°C not only ensures that the casting does not deform, but also can greatly save heat treatment energy.

[0058] As another example, the cast alloy material or casting is solution treated at 510° C.-530° C. for 3 h-8 h and quenched, and then aged at 155° C.-175° C. for 1 h-10 h. The heat treatment conditions of this example are suitable for using high-strength and tough Al-Si alloys to manufacture other products with thick walls that are not easily deformed.

[0059] According to the present invention, using Al 3 In-situ generation of Al-SiC particles and C-TiB by instability of BC seeds in Al-Si-Ti melt 2 Particles can refine the grain size and improve the grain morphology, improve the flowability, forming performance of the alloy melt and the surface quality and consistency of the casting, improve the density, reduce defects such as shrinkage and shrinkage holes, and can also effectively cooperate with eutectic Si to build a strengthening structure, and can regulate and promote the efficient precipitation of the aging phase during the heat treatment process, thereby improving the one-piece die-casting formability and toughness of the material.

[0060] Example 1

[0061] According to the following composition ratio: Al-10Si-1.2Zn-0.25Mg-0.1Ti-0.1RE-0.03Sr-0.1Fe-0.06Mn-0.03Cr-0.25(C-TiB 2 )-0.27(Al-SiC), prepare the raw materials required for high-strength and tough Al-Si alloys, pure aluminum, pure silicon, pure magnesium, pure zinc, Al-RE alloy, Al-Sr alloy, Al-Fe alloy, Al-Cr alloy, Al-Mn alloy, Al-Ti alloy, Al-Al 3 BC seed alloy.

[0062] Add some pure aluminum and Al-Al into the melting furnace 3When the BC seed alloy is heated to 820℃, pure silicon and Al-Ti alloy are added to the melt. After complete dissolution, the Si mass percentage in the alloy is guaranteed to be 23wt.%, providing sufficient Si concentration for the reaction. The melt temperature is adjusted to 800℃, and intermittent stirring is applied to promote the reaction, and the mixture is kept warm for 15 minutes.

[0063] After the above melt reaction is completed, add the remaining pure aluminum, Al-Fe alloy, Al-Cr alloy and Al-Mn alloy, adjust the melt temperature to 760°C after dissolution, add pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy, stir until dissolved and keep warm for 20 minutes.

[0064] The above alloy melts are sampled and tested. After the composition is qualified, the melt temperature is maintained at 740°C, the melt is refined for 20 minutes, and the alloy composition is tested again. After passing the test, the alloy material or casting is cast.

[0065] The cast alloy material or casting is subjected to casting quenching treatment at 450°C and aging at 160°C for 4 hours, and finally a high-strength and tough Al-Si alloy material for a subframe is obtained.

[0066] According to the mechanical property test at room temperature, the high strength and toughness Al-Si alloy material in Example 1 has a yield strength of 221 MPa, a tensile strength of 338 MPa, and an elongation of 6.5%.

[0067] Example 2

[0068] According to the following composition ratio: Al-8.5Si-2.5Zn-0.3Mg-0.12Ti-0.15RE-0.025Sr-0.12Fe-0.07Mn-0.04Cr-0.4(C-TiB 2 )-0.43(Al-SiC), prepare the raw materials required for high-strength and tough Al-Si alloys, pure aluminum, pure silicon, pure magnesium, pure zinc, Al-RE alloy, Al-Sr alloy, Al-Fe alloy, Al-Cr alloy, Al-Mn alloy, Al-Ti alloy, Al-Al 3 BC seed alloy.

[0069] Add some pure aluminum and Al-Al into the melting furnace 3 When the BC seed alloy is heated to 800℃, pure silicon and Al-Ti alloy are added to the melt. After complete dissolution, the Si mass percentage in the alloy is guaranteed to be 26wt.%, providing sufficient Si concentration for the reaction. The melt temperature is adjusted to 825℃, and intermittent stirring operation is applied to promote the reaction, and the temperature is kept for 40 minutes.

[0070] After the above melt reaction is completed, add the remaining pure aluminum, Al-Fe alloy, Al-Cr alloy and Al-Mn alloy, adjust the melt temperature to 750°C after dissolution, add pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy, stir until dissolved and keep warm for 20 minutes.

[0071] The above alloy melts are sampled and tested. After the composition is qualified, the melt temperature is maintained at 750°C, the melt is refined for 20 minutes, and the alloy composition is tested again. After passing the test, the alloy material or casting is cast.

[0072] The cast alloy material or casting is solution treated at 510°C for 6 hours and quenched, and then aged at 170°C for 6 hours to finally obtain a high-strength and tough Al-Si alloy material.

[0073] According to the mechanical property test at room temperature, the high strength and toughness Al-Si alloy material in Example 1 has a yield strength of 325 MPa, a tensile strength of 401 MPa, and an elongation of 5.0%.

[0074] As described above, the high-strength and toughness Al-Si alloy and the preparation method thereof according to the embodiments of the present invention can achieve the following beneficial technical effects which are not limited to the following.

[0075] The high-strength and tough Al-Si alloy according to the present invention comprises in-situ generated Al-SiC particles and C-TiB 2 Particles can refine the grain size and improve the grain morphology, improve the flowability, forming performance of the alloy melt and the surface quality and consistency of the casting, improve the density, reduce defects such as shrinkage and shrinkage holes, and can also effectively cooperate with eutectic Si to build a strengthening structure, and can regulate and promote the efficient precipitation of the aging phase during the heat treatment process, thereby improving the one-piece die-casting formability and toughness of the material.

[0076] According to the present invention, since Al is doped into SiC particles, the mass fraction of SiC particles can be increased on the one hand, and the size of SiC particles can be further reduced on the other hand, thereby helping to improve the strengthening and toughening effect of SiC particles.

[0077] According to the present invention, by using Al 3 In-situ generation of Al-SiC particles and C-TiB by instability of BC seeds in Al-Si-Ti melt 2 The particles have low raw material cost, simple process, green environmental protection and high industrialization potential. The high-strength and tough Al-Si alloy prepared thereby has high strength and toughness.

[0078] While exemplary embodiments of the present invention have been described in detail with reference to examples, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims.

Claims

1. A high-strength and tough Al-Si alloy, characterized in that: The high-strength and toughness Al-Si alloy includes an Al matrix, Si, C-TiB2 particles, and Al-SiC particles generated in situ by the reaction of Al3BC particles and Si. Based on 100wt.% of the high-strength and toughness Al-Si alloy, the Si content is 8.5wt.%-12wt.%. The Al-SiC particles are Al-doped SiC particles, have the crystal structure of SiC and are doped with trace Al elements. The C-TiB2 particles are C-doped TiB2 particles, have the crystal structure of TiB2 and are doped with trace C elements.

2. The high-strength and tough Al-Si alloy according to claim 1, characterized in that: Based on 100wt.% of the Al-SiC particles, the Al doping amount is greater than or equal to 0.05wt.% and less than or equal to 8wt.%, and based on 100wt.% of the C-TiB2 particles, the C doping amount is greater than or equal to 0.02wt.% and less than or equal to 1.8wt.%.

3. The high-strength and tough Al-Si alloy according to claim 1, characterized in that: Based on 100wt.% of the high-strength and toughness Al-Si alloy, the content of the Al-SiC particles is 0.03wt.%-2wt.%, and the content of the C-TiB2 particles is 0.028wt.%-1.7wt.%.

4. The high-strength and tough Al-Si alloy according to claim 1, characterized in that: Based on 100 wt. % of the high-strength and toughness Al-Si alloy, the content of C is 0.01 wt. %-0.6 wt. %, and the content of B is 0.009 wt. %-0.54 wt. %.

5. The high strength and toughness Al-Si alloy according to any one of claims 1 to 4, characterized in that: The high-strength and tough Al-Si alloy further comprises at least one of Ti, Mg, Zn, RE, Sr, Fe, Cr and Mn. Based on 100wt.% of the high-strength and toughness Al-Si alloy, the Ti content is 0.08wt.%-1.3wt.%, the Mg content is 0.1wt.%-1.0wt.%, the Zn content is less than or equal to 5.0wt.%, the RE content is 0.01wt.%-0.3wt.%, the Sr content is 0.01wt.%-0.05wt.%, the Fe content is less than or equal to 0.3wt.%, the Cr content is 0.01wt.%-0.15wt.%, and the Mn content is 0.05wt.%-0.7wt.%. The total content of other impurity elements in the high-strength and toughness Al-Si alloy does not exceed 0.5wt.%.

6. A method for preparing a high-strength and tough Al-Si alloy, characterized in that: The preparation method comprises: Adding a first portion of aluminum source and Al-Al3BC seed alloy into a smelting furnace, heating and melting to 760°C-880°C, wherein the Al-Al3BC seed alloy comprises Al3BC particles, and the addition amount of the Al-Al3BC seed alloy is 0.2wt.%-30.0wt.% of the total weight of the high-strength and tough Al-Si alloy; Add pure silicon and Al-Ti alloy to the melt to ensure that the mass percentage of Si in the melt is 22.0wt.%-27.0wt.%, adjust the melt temperature to 780℃-830℃ and react for 15min-45min; After the reaction is completed, the melt temperature is maintained at 780° C.-830° C., and a second portion of aluminum source is added to the melt to ensure that the Si content in the high-strength and tough Al-Si alloy is 8.5wt.%-12wt.%.

7. The method for preparing a high-strength and tough Al-Si alloy according to claim 6, characterized in that: Based on 100 wt. % of the Al-Al3BC seed alloy, the content of the Al3BC particles is 0.3 wt. %-20.0 wt. %.

8. The method for preparing a high-strength and tough Al-Si alloy according to claim 6, characterized in that: The preparation method further comprises: After the reaction is completed, the melt temperature is maintained at 780°C-830°C, and Al-Fe alloy, Al-Cr alloy, and Al-Mn alloy are added to the melt; The melt temperature is adjusted to 720°C-780°C, pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy are added and kept warm for 15min-30min.

9. The method for preparing a high-strength and tough Al-Si alloy according to claim 8, characterized in that: The preparation method further comprises: After adding pure magnesium, pure zinc, Al-RE alloy and Al-Sr alloy and keeping the temperature for 15-30 minutes, the melt is refined at a temperature of 730-760°C for 10-30 minutes and then poured to obtain the alloy material or casting.

10. The method for preparing a high-strength and tough Al-Si alloy according to claim 9, characterized in that: The cast alloy material or casting is quenched at 400℃-500℃ and aged at 155℃-175℃ for 1h-10h, or The cast alloy material or casting is solution treated at 510°C-530°C for 3h-8h and quenched, and then aged at 155°C-175°C for 1h-10h.

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