High formability high volume fraction sic / alsi10mg composite material and additive manufacturing method thereof

Abstract

This invention discloses a high-formability, high-volume-fraction SiC / AlSi10Mg composite material and its additive manufacturing method. The manufacturing method includes: pretreating SiC particles, then depositing a 1.0-2.0 μm pure aluminum coating on their surface using vacuum ion plating to obtain SiC@Al core-shell structure modified particles; mixing these modified particles with AlSi10Mg powder to obtain a composite powder with a modified particle volume fraction of 20%-30%; printing according to SLM forming parameters matched to the modified particle volume fraction; and finally performing stress-relief heat treatment. This invention effectively releases strong thermal mismatch stress and isolates the molten aluminum by constructing a pure aluminum buffer layer with dual interfaces, preventing the formation of brittle Al4C3 phase. It solves the forming problems of easy cracking, powder spreading, and poor wettability in high-content SiC systems, resulting in parts with high density and excellent comprehensive mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology for metal matrix composites, and more specifically, to a high formability, high volume fraction SiC / AlSi10Mg composite material and its additive manufacturing method. Background Technology

[0002] High-volume-fraction SiC particle-reinforced aluminum matrix composites possess both the lightweight properties of aluminum alloys and the advantages of ceramic particles, such as high modulus, low expansion, and wear resistance, making them promising for applications in aerospace precision structural components, high-performance electronic heat dissipation packaging, and key automotive parts. When the SiC volume fraction reaches 20%–30%, the thermophysical and mechanical properties of the composite material are significantly improved, further expanding its application potential under extreme service conditions. Selective laser melting (SLM), as a typical additive manufacturing technology, can achieve high-precision near-net-shape forming of complex structural parts, breaking through the forming limitations of traditional casting and powder metallurgy, and providing a new technical path for the preparation of high-volume-fraction SiC / AlSi10Mg composites.

[0003] However, when adapting high volume fraction (20%~30%) SiC / AlSi10Mg systems to additive manufacturing technology, the following insurmountable process and performance bottlenecks exist: the difference in thermal expansion coefficients between SiC particles and the AlSi10Mg matrix is ​​significant (AlSi10Mg's room temperature thermal expansion coefficient is approximately 22 × 10⁻⁶). -6 / ℃, SiC particles approximately 4.5×10 -6 / ℃). Introducing 20%~30% high-content SiC, under the extreme environment of rapid melting and thermal cycling in additive manufacturing with high-energy lasers, the interfacial thermal mismatch stress is amplified exponentially, easily leading to fatal defects such as matrix cracking, particle interface debonding, and part delamination. High-content SiC particles have poor flowability and poor wettability with molten aluminum. During the powder spreading process in additive manufacturing, powder agglomeration and uneven spreading are very likely to occur, and at high cooling rates, the molten aluminum cannot fully encapsulate the SiC particles, significantly reducing the forming density and exacerbating forming difficulties. Furthermore, under the high temperature of the laser, SiC easily comes into direct contact with the molten aluminum and generates brittle and harmful phases (such as Al4C3 phase). The formation of this brittle phase further weakens the interfacial bonding, and combined with the high brittleness inherent in the high-content ceramic phase itself, ultimately leads to cracking and scrapping of additively manufactured parts, resulting in an extremely low yield rate.

[0004] Currently, research on SLM forming of SiC / AlSi10Mg composites mainly focuses on low volume fraction systems (typically below 15%) or conventional surface modification methods. For example, modifying SiC particles using electroless nickel or copper plating improves the interfacial bonding of the composite to some extent, but these coatings have limited compatibility with the aluminum matrix, resulting in insufficient stress buffering and failing to meet the comprehensive requirements of high volume fraction systems for interface control and thermal stress relief. Furthermore, related patented technologies also have several limitations: Chinese patent application CN110170653A discloses a self-compensating SiCp / AlSi composite material and its preparation method. This method involves surface oxidation of the reinforcing SiC powder in a high-temperature tube furnace, followed by ball milling and mixing with matrix powder, and then laser melting. However, its drawbacks are as follows: Treating SiC solely through high-temperature surface oxidation does not create a robust physical barrier layer between SiC and the molten aluminum. During the rapid melting process with extremely high laser energy density, it is still impossible to completely isolate the contact between SiC and the molten aluminum, easily generating the harmful Al4C3 brittle phase. Simultaneously, the simple oxide layer cannot provide a flexible buffer, making it difficult to effectively release the huge thermal mismatch stress between the high volume fraction SiC and the aluminum matrix, resulting in a high tendency for hot cracking in the manufactured parts. Furthermore, the high-energy ball milling method used destroys the sphericity of the matrix powder, leading to poor powder flowability and severely affecting the uniformity of powder spreading in additive manufacturing.

[0005] Chinese patent application CN110331324A discloses a ceramic-aluminum composite material for additive manufacturing, its preparation method, and an additive manufacturing method for ceramic-aluminum composite structural parts. This method utilizes electrostatic self-assembly technology to adsorb negatively charged nano-ceramic powder particles onto the surface of positively charged aluminum alloy powder particles in an aqueous solution. However, its drawbacks are: this method mainly relies on the physical electrostatic adsorption of surface charges, making it difficult for ceramic particles to form a continuous and firmly bonded interfacial coating layer on the matrix surface; more importantly, this physical adhesion method cannot avoid the direct high-temperature reaction between ceramic particles and molten aluminum during SLM forming, nor can it provide a continuous stress buffer medium to alleviate the significant difference in thermal expansion coefficients between the two. Therefore, this method is only suitable for low volume fraction (5%-20%) and nano-scale ceramic particle systems, and cannot cope with the challenges of agglomeration and cracking of 20%~30% micron-scale high volume fraction SiC composite materials in additive manufacturing.

[0006] Chinese patent application CN108480625A discloses a method for forming silicon carbide particle-reinforced aluminum matrix composites based on selective laser melting technology. This method mechanically mixes 8%-12% SiC powder with AlSi10Mg powder using a powder mixer without damaging the sphericity of the aluminum matrix powder, and then shapes the composite by controlling the powder layer thickness and laser parameters. However, its drawback is that this technology is only suitable for low volume fraction SiC systems of 8%~12%. When the SiC volume fraction is significantly increased to 20%~30%, without any surface modification treatment of the SiC particles, mechanical mixing and optimization of printing process parameters alone cannot overcome the severe poor wettability and surge in interfacial thermal stress caused by high SiC content. If this method is directly used to print high volume fraction components, severe agglomeration, unfused voids, and large-area thermal mismatch cracking will inevitably occur, leading to a sharp deterioration in the forming density and mechanical properties.

[0007] Based on the defects in the existing technologies, such as large interfacial thermal mismatch stress, easy formation of brittle harmful phases, and poor spreadability and wettability of high volume fraction powders, there is an urgent need for a new material modification and additive manufacturing technology to completely block harmful interfacial reactions and effectively relieve thermal stress, thereby achieving high density and defect-free stable forming of high volume fraction SiC / AlSi10Mg composite material components. Summary of the Invention

[0008] One of the technical problems to be solved by the present invention is to provide an additive manufacturing method for a high formability, high volume fraction SiC / AlSi10Mg composite material, in order to solve the problems in the prior art where high content SiC particles are prone to strong thermal mismatch cracking, brittle harmful phase formation, and poor powder spreading and wettability during selective laser melting.

[0009] To overcome the shortcomings of the prior art, the present invention provides an additive manufacturing method for a high-formability, high-volume-fraction SiC / AlSi10Mg composite material, comprising the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: SiC particles are pretreated, and then a pure aluminum coating is deposited on the surface of the SiC particles by vacuum ion plating to obtain SiC@Al core-shell structure modified particles with a continuous and dense pure aluminum coating on the surface. The thickness of the pure aluminum coating is 1.0~2.0μm. S2: Preparation of composite powder: The SiC@Al core-shell structure modified particles and gas-atomized AlSi10Mg powder are mixed, kneaded and dried according to the volume fraction ratio to obtain a high volume fraction composite powder, wherein the volume fraction of the SiC@Al core-shell structure modified particles in the high volume fraction composite powder is 20%~30%; S3: Selective laser melting: The high volume fraction composite powder is placed in a selective laser melting device, and the corresponding selective laser melting parameters are matched according to the volume fraction of the SiC@Al core-shell structure modified particles to form a composite material part. S4: Stress-relieving heat treatment: The composite material part is subjected to heat preservation and furnace cooling treatment to obtain a high formability, high volume fraction SiC / AlSi10Mg composite material.

[0010] Compared with the prior art, the additive manufacturing method of the high formability and high volume fraction SiC / AlSi10Mg composite material of the present invention has the following advantages: The present invention replaces the exposed silicon carbide particles or the modification method of only simple surface oxidation and physical adsorption treatment in the prior art with the deposition of a pure aluminum coating layer with a thickness of 1.0~2.0μm on the SiC surface through vacuum ion plating process, thereby constructing a continuous and dense SiC@Al core-shell structure. The pure aluminum coating layer of the above thickness acts as a physical barrier medium in the high-temperature transient forming process of selective laser melting, avoiding direct contact between the inner SiC core and the external highly active aluminum melt, inhibiting the precipitation reaction of brittle harmful phases such as Al4C3, and maintaining the metallurgical bonding strength of the interface. The pure aluminum layer itself has good plasticity, and as a flexible buffer zone between the low thermal expansion coefficient SiC and the high thermal expansion coefficient AlSi10Mg matrix, it can absorb and release the thermal mismatch stress generated by the alternating hot and cold cycles of additive manufacturing, reducing the tendency for macroscopic cracking and microcrack initiation. This invention improves the fluidity of ceramic particles with a volume fraction of up to 20%~30% and their wettability with the matrix melt by mixing modified particles with aluminum-based surface properties with gas-atomized aluminum alloy matrix powder, overcoming the process bottleneck of easy agglomeration and uneven powder distribution of high-doped powder. Furthermore, by combining selective laser melting forming parameters matched to different high volume fraction nodes, the laser energy input and the thermophysical properties of the specific doped powder bed are highly synergistic, avoiding pores and incomplete fusion defects caused by excess or insufficient energy, and realizing crack-free near-net-shape forming of high-content silicon carbide reinforced aluminum matrix composites with both high density and excellent mechanical properties.

[0011] In one possible implementation, step S1 includes pretreatment consisting of sequential degreasing, acid pickling and roughening, sensitization and activation treatments.

[0012] In one possible implementation, the degreasing is performed by ultrasonic cleaning with acetone solution for 8-12 minutes; the acid pickling and roughening is performed by soaking in hydrofluoric acid solution with a mass fraction of 5%-15% for 3-7 minutes; the sensitization is performed by treatment with stannous chloride-hydrochloric acid solution for 3-5 minutes; and the activation is performed by treatment with silver nitrate-ammonia solution for 2-4 minutes.

[0013] Compared with the prior art, the present invention adopts the above-mentioned technical solution, which uses acetone ultrasonic to remove organic impurities on the surface of SiC particles, and uses a specific mass fraction of 5%~15% hydrofluoric acid solution to peel off the natural silicon oxide layer on the particle surface and construct a micro-uneven morphology on the surface, increasing the surface roughness; combined with 3~5 min and 2~4 min of stannous chloride sensitization and silver nitrate activation treatment, catalytically active silver-centered microparticles are uniformly deposited on the roughened SiC surface; this further enhances the chemical activity of the SiC particle surface, and also provides it with dense nucleation sites and mechanical anchoring points, ensuring that the pure aluminum coating generated by subsequent vacuum ion plating can form a very strong interfacial bond with the SiC particle surface, preventing the pure aluminum coating from peeling or falling off under the severe thermal stress impact of the selective laser melting process, and maintaining the structural stability of the core-shell particles.

[0014] In one possible implementation, the parameters of the vacuum ion plating process in step S1 include: A medium-purity aluminum target with a purity of not less than 99.9% is used; The vacuum degree is 3.0 × 10⁻⁶. -3 ~8.0×10 -3 Pa; The target current is 8~15A; The substrate bias voltage is -100 to -200V; The deposition time is 60-120 min; The deposition atmosphere is argon, and the flow rate of the argon is 20~40 sccm.

[0015] Compared with existing technologies, the above technical solution achieves 3.0×10 -3 ~8.0×10 -3 The high vacuum of Pa and the argon flow rate of 20~40 sccm reduce the collision and scattering loss of aluminum ions during flight, ensuring the mean free path of the deposited particles. The target current of 8~15A and the substrate bias voltage of -100~-200V work synergistically to give the aluminum ions suitable bombardment kinetic energy, preventing excessive energy from causing excessive internal stress in the deposited layer or thermal damage to the particle surface, and also avoiding the loose and porous coating layer caused by insufficient kinetic energy. Combined with the control of deposition time of 60~120min, the thickness of the pure aluminum coating layer is limited to the range of 1.0~2.0μm. This embodiment ensures that a pure, continuous and highly dense pure aluminum coating layer is obtained on the SiC surface, and enhances the ability of this barrier layer to resist direct erosion by high-temperature aluminum-based melt during laser forming.

[0016] In one possible implementation, in step S2, the particle size of the gas-atomized AlSi10Mg powder is 15~45μm; The mixing process is carried out mechanically using a three-dimensional mixer, with a mixing time of 1.5 to 2.5 hours. The drying process is carried out in a vacuum drying oven at a temperature of 70-90°C for 3-5 hours.

[0017] Compared with existing technologies, this embodiment utilizes the excellent sphericity and flowability of gas-atomized AlSi10Mg powder with a particle size range of 15~45μm, which forms a good match with micron-sized modified SiC core-shell particles in terms of size and spatial packing. Further, a three-dimensional mixer is used for mechanical mixing for 1.5~2.5 hours, enabling the powder to achieve high dispersion and uniform mixing under multi-directional shear forces. This avoids the powder sphericity damage and mechanical wear of the pure aluminum outer layer that are easily caused by traditional high-energy ball milling processes. Subsequently, the powder is dried in a vacuum environment at 70~90℃ for 3~5 hours to remove residual moisture adsorbed on the powder surface, preparing a high-volume-fraction composite powder with excellent flowability, uniform component distribution, and dryness. This improves the smoothness and density of the selective laser melting powder spreading process, eliminates internal porosity defects caused by water vapor evaporation during the forming process, and ensures the forming quality and mechanical property consistency of high-content composite material parts.

[0018] In one possible implementation, in step S3, the selected area laser melting forming parameters include laser power, scanning speed, layer thickness, scanning spacing, and substrate preheating temperature. The laser power is 300~420W; The scanning speed is 700~1300 mm / s; The layer thickness is 25~35μm; The scanning interval is 0.10~0.14mm; The substrate preheating temperature is 140~170℃.

[0019] Compared with existing technologies, the above-mentioned technical solution effectively reduces the temperature gradient between the forming base plate and the molten layer by using a substrate preheating temperature of 140~170℃, alleviating the accumulation of residual thermal stress during rapid solidification. Furthermore, by matching a laser power of 300~420W and a scanning speed of 700~1300mm / s, sufficient and suitable volume energy density can be provided in local areas of the powder bed. This ensures complete melting of the aluminum alloy matrix powder while avoiding local metal vaporization or damage to the pure aluminum cladding layer on the SiC surface due to excessive heat input. Combined with a forming layer thickness of 25~35μm and a scanning interval of 0.10~0.14mm, this embodiment ensures sufficient overlap and element diffusion between adjacent melt channels and interlayer molten pools, reducing the incidence of unfused pores and porosity defects within the composite material, and improving the macroscopic density and mechanical property consistency of additively manufactured parts in high volume fraction systems.

[0020] In one possible implementation, in step S3, the matched selected area laser melting forming parameters, based on the volume fraction of the SiC@Al core-shell structure modified particles, include: When the volume fraction of the SiC@Al core-shell modified particles is greater than or equal to 20% and less than or equal to 23.5%, the laser power is 300~360W, the scanning speed is 1000~1100mm / s, the layer thickness is 25~30μm, the scanning spacing is 0.10~0.12mm, and the substrate preheating temperature is 140~160℃; When the volume fraction of the SiC@Al core-shell structure modified particles is greater than 23.5% and less than or equal to 26.5%, the laser power is 340~360W, the scanning speed is 1100~1300mm / s, the layer thickness is 30μm, the scanning spacing is 0.12mm, and the substrate preheating temperature is 150℃. When the volume fraction of the SiC@Al core-shell structure modified particles is greater than 26.5% and less than or equal to 30%, the laser power is 380~420W, the scanning speed is 700~900mm / s, the layer thickness is 30~35μm, the scanning spacing is 0.12~0.14mm, and the substrate preheating temperature is 150~170℃.

[0021] Compared with existing technologies, this embodiment, employing the above-mentioned technical solution, can control the heat input characteristics of the powder bed and the dynamic behavior of the molten pool for different gradients of high ceramic doping: as the volume fraction of SiC particles increases, the flow resistance and liquid phase viscosity of the aluminum melt increase significantly. For the high doping range of 26.5%~30%, a high laser power of 380~420W and a low scanning speed of 700~900mm / s are used to prolong the liquid state maintenance time of the high-temperature molten pool, promoting the full spread of the high-viscosity melt and filling the tiny gaps between the dense ceramic particles. For the relatively low doping range of ≥20% and ≤23.5%, a moderate power of 300~360W and a high scanning speed of 1000~1100mm / s are used to avoid excessive energy leading to boiling of the molten pool and excessive burning of the pure aluminum coating. The above-mentioned dynamic matching linkage parameter design overcomes the local overheating or non-fusion defects that are easily caused by single fixed parameters when facing variable composition powders, ensuring that silicon carbide reinforced aluminum matrix composites at each volume fraction can obtain excellent interfacial wettability and near-fully dense forming quality.

[0022] In one possible implementation, in step S4, the heat preservation and furnace cooling process is as follows: heat preservation at 180~220℃ for 1.5~2.5h, followed by furnace cooling to room temperature.

[0023] Compared with existing technologies, the above-mentioned technical solution utilizes a specific low-temperature holding range of 180~220℃ to perform stress-relief annealing on composite material parts formed by selective laser melting. This activates the slip of dislocations in the matrix lattice and promotes the full release of microscopic residual thermal stress, while avoiding abnormal grain growth or over-aging softening of the aluminum alloy matrix caused by excessive heating temperature, thus preserving the original high-strength skeleton of the material. With a suitable holding time of 1.5~2.5h and an extremely slow cooling method of furnace cooling, this embodiment can minimize the temperature gradient between the inside and outside of the part, preventing the generation of new thermal stress during secondary cooling. The heat treatment system of this embodiment eliminates the hidden danger of macroscopic residual tensile stress caused by the alternating hot and cold of additive manufacturing, improves the dimensional stability and deformation resistance of composite material parts, and ensures the structural reliability of complex structural parts in subsequent service environments.

[0024] Another technical problem to be solved by the present invention is to provide a high formability, high volume fraction SiC / AlSi10Mg composite material, in order to solve the problems existing in the prior art where high content silicon carbide reinforced aluminum matrix composite materials suffer from severe interfacial thermal mismatch during hot processing, are prone to inducing internal stress microcracks, and are extremely prone to generating brittle and harmful phases, leading to the deterioration of comprehensive mechanical properties.

[0025] To overcome the shortcomings of the prior art, the present invention also provides a high formability, high volume fraction SiC / AlSi10Mg composite material, which is prepared by the above-mentioned additive manufacturing method.

[0026] In one possible embodiment, the composite material comprises an AlSi10Mg alloy matrix and SiC@Al core-shell structure modified particles dispersed in the AlSi10Mg alloy matrix. The volume fraction of the SiC@Al core-shell structure modified particles is 20% to 30%, and the surface of the SiC@Al core-shell structure modified particles is coated with a pure aluminum coating with a thickness of 1.0 to 2.0 μm. The pure aluminum coating forms a double-interface metallurgical bond with the internal SiC particles and the external AlSi10Mg alloy matrix.

[0027] Compared with existing technologies, the high-formability, high-volume-fraction SiC / AlSi10Mg composite material of this invention has the following advantages: The composite material of this invention replaces the exposed, dispersed, or simply surface-oxidized silicon carbide reinforcing phase in existing technologies with SiC@Al core-shell modified particles having a continuous pure aluminum coating layer with a thickness of 1.0~2.0 μm. These modified particles are dispersed in the AlSi10Mg alloy matrix at a high volume fraction of 20%~30%. The 1.0~2.0 μm thick pure aluminum coating acts as a physical barrier in the high-temperature transient environment of selective laser melting, cutting off the direct contact between the internal silicon carbide and the external highly reactive aluminum alloy melt. The contact path inhibits the precipitation of harmful brittle phases; the excellent plastic deformation capacity of pure aluminum itself forms a flexible buffer zone between the low thermal expansion coefficient of silicon carbide and the high thermal expansion coefficient of aluminum alloy matrix, effectively absorbing and dissipating the huge thermal mismatch stress accumulated during the alternating hot and cold process of additive manufacturing. The surface of the core-shell particles wrapped by pure aluminum exhibits metallic properties that are highly consistent with the aluminum alloy matrix, which greatly improves the wetting state of high-doped ceramic particles in the matrix melt. The above-mentioned core-shell structure and component distribution solve the problems of easy cracking and the presence of brittle interfacial phases in high-content silicon carbide systems in the background technology, and endow the composite material with extremely high density and excellent tensile and deformation resistance mechanical properties. Attached Figure Description

[0028] Figure 1 This is a bar chart comparing the mechanical properties of the composite materials of Example 1 and Comparative Example 1 of the present invention; Figure 1 In the diagram, (a) shows a comparison of tensile strength; (b) shows a comparison of elastic modulus. Figure 2 Microstructure diagram of carbide precipitation in unmodified SiC (25 vol.%) reinforced AlSi10Mg alloy; Figure 3 The image shows the microstructure of the SiC (25 vol.%) reinforced AlSi10Mg alloy modified by pure aluminum plating according to the present invention (showing no obvious carbide precipitation). Detailed Implementation

[0029] First, those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0030] This invention provides an additive manufacturing method for a high-formability, high-volume-fraction SiC / AlSi10Mg composite material, comprising the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: SiC particles are pretreated, and then a pure aluminum coating is deposited on the surface of the SiC particles by vacuum ion plating to obtain SiC@Al core-shell structure modified particles with a continuous and dense pure aluminum coating on the surface. The thickness of the pure aluminum coating is 1.0~2.0μm. S2: Preparation of composite powder: SiC@Al core-shell structure modified particles and gas-atomized AlSi10Mg powder are mixed, kneaded and dried according to the volume fraction ratio to obtain high volume fraction composite powder, wherein the volume fraction of SiC@Al core-shell structure modified particles in the high volume fraction composite powder is 20%~30%; S3: Selective Laser Melting: High volume fraction composite powder is placed in a selective laser melting device. Based on the volume fraction of SiC@Al core-shell structure modified particles, the corresponding selective laser melting parameters are matched for printing to obtain composite material parts. S4: Stress-relieving heat treatment: The composite material parts are subjected to heat preservation and furnace cooling treatment to obtain high formability and high volume fraction SiC / AlSi10Mg composite materials.

[0031] As a preferred embodiment, in step S1, the pretreatment includes degreasing, acid pickling and roughening, sensitization and activation treatments performed sequentially.

[0032] As a preferred method, degreasing is performed by ultrasonic cleaning with acetone solution for 8-12 minutes; acid pickling and roughening is performed by soaking in hydrofluoric acid solution with a mass fraction of 5%-15% for 3-7 minutes; sensitization is performed by treatment with stannous chloride-hydrochloric acid solution for 3-5 minutes; and activation is performed by treatment with silver nitrate-ammonia solution for 2-4 minutes.

[0033] As a preferred embodiment, the parameters for vacuum ion plating in step S1 include: A medium-purity aluminum target with a purity of not less than 99.9% is used; The vacuum degree is 3.0 × 10⁻⁶. -3 ~8.0×10 -3 Pa; The target current is 8~15A; The substrate bias voltage is -100 to -200V; The deposition time is 60-120 min; The deposition atmosphere is argon, and the flow rate of the argon is 20~40 sccm.

[0034] As a preferred embodiment, in step S2, the particle size of the gas-atomized AlSi10Mg powder is 15~45μm; The mixing process is carried out mechanically using a three-dimensional mixer, with a mixing time of 1.5 to 2.5 hours. Drying is carried out in a vacuum drying oven at a temperature of 70-90℃ for 3-5 hours.

[0035] As a preferred embodiment, in step S3, the selected area laser melting forming parameters include laser power, scanning speed, layer thickness, scanning spacing, and substrate preheating temperature. The laser power is 300~420W; The scanning speed is 700~1300 mm / s; The layer thickness is 25~35μm; The scanning interval is 0.10~0.14mm; The substrate preheating temperature is 140~170℃.

[0036] As a preferred embodiment, in step S3, the selected area laser melting forming parameters, based on the volume fraction of the SiC@Al core-shell structure modified particles, include: When the volume fraction of SiC@Al core-shell modified particles is greater than or equal to 20% and less than or equal to 23.5%, the laser power is 300~360W, the scanning speed is 1000~1100mm / s, the layer thickness is 25~30μm, the scanning spacing is 0.10~0.12mm, and the substrate preheating temperature is 140~160℃. When the volume fraction of SiC@Al core-shell modified particles is greater than 23.5% and less than or equal to 26.5%, the laser power is 340~360W, the scanning speed is 1100~1300mm / s, the layer thickness is 30μm, the scanning spacing is 0.12mm, and the substrate preheating temperature is 150℃. When the volume fraction of SiC@Al core-shell modified particles is greater than 26.5% and less than or equal to 30%, the laser power is 380~420W, the scanning speed is 700~900mm / s, the layer thickness is 30~35μm, the scanning spacing is 0.12~0.14mm, and the substrate preheating temperature is 150~170℃.

[0037] As a preferred option, in step S4, the heat preservation and furnace cooling treatment is as follows: heat preservation at 180~220℃ for 1.5~2.5h, followed by furnace cooling to room temperature.

[0038] The present invention also provides a high formability, high volume fraction SiC / AlSi10Mg composite material, which is prepared by the above-described additive manufacturing method.

[0039] As a preferred embodiment, the composite material includes an AlSi10Mg alloy matrix and SiC@Al core-shell structure modified particles dispersed in the AlSi10Mg alloy matrix. The volume fraction of the SiC@Al core-shell structure modified particles is 20%~30%, and the surface of the SiC@Al core-shell structure modified particles is coated with a pure aluminum coating with a thickness of 1.0~2.0μm. The pure aluminum coating forms a double-interface metallurgical bond with the internal SiC particles and the external AlSi10Mg alloy matrix.

[0040] The following are embodiments incorporating specific data to further elaborate on the above-described technical solutions of the present invention: Example 1 This embodiment provides a high-formability, high-volume-fraction SiC / AlSi10Mg composite material and its additive manufacturing method, specifically including the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: Pretreatment: Raw SiC particles with an average particle size of 30 μm were placed in acetone solution and ultrasonically cleaned for 10 min to remove oil; then they were soaked in 10% hydrofluoric acid solution for 5 min for acid washing and roughening; then they were treated with stannous chloride-hydrochloric acid solution for 4 min for sensitization; finally, they were treated with silver nitrate-ammonia solution for 3 min for activation.

[0041] Vacuum ion plating treatment: The pretreated SiC particles are placed in a vacuum ion plating apparatus using a medium-purity aluminum target with a purity of not less than 99.9%, and the process is carried out under a vacuum of 5.0 × 10⁻⁶. -3 Deposition was carried out for 90 min under the following conditions: Pa, target current of 12 A, substrate bias voltage of -150 V, and argon atmosphere (flow rate of 30 sccm). SiC@Al core-shell modified particles with a continuous and dense pure aluminum coating were finally obtained. The thickness of this pure aluminum coating was measured to be 1.5 μm.

[0042] S2: Preparation of composite powder: The SiC@Al core-shell modified particles prepared above were mixed with gas-atomized AlSi10Mg powder (particle size 15~45μm) at a volume fraction ratio, so that the volume fraction of SiC@Al core-shell modified particles in the mixed powder was 25%. Then, the mixture was mechanically mixed in a three-dimensional mixer for 2 hours, and finally dried in a vacuum drying oven at 80℃ for 4 hours to obtain a high volume fraction composite powder.

[0043] S3: Selective Laser Melting: High volume fraction composite powder was placed in a selective laser melting (SLM) device, and printing was performed using appropriate forming parameters matched to a 25% volume fraction. Specific parameters were: laser power 350W, scanning speed 1200mm / s, layer thickness 30μm, scanning spacing 0.12mm, and substrate preheating temperature 150℃. The resulting composite material part was then obtained.

[0044] S4: Stress-relieving heat treatment: The composite material part was placed in a heat treatment furnace and held at 200°C for 2 hours, and then cooled to room temperature with the furnace to finally obtain a high formability, high volume fraction SiC / AlSi10Mg composite material.

[0045] Test results: The composite material prepared in this embodiment has a density of 98.5%, with no cracks inside or on the surface of the part, and no Al4C3 phase was observed in the microstructure; the room temperature tensile strength is 420 MPa, the elastic modulus is 110 GPa, and the coefficient of thermal expansion is 12 × 10⁻⁶. -6 / ℃.

[0046] Example 2 This embodiment provides a high-formability, high-volume-fraction SiC / AlSi10Mg composite material and its additive manufacturing method, specifically including the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: The pretreatment steps were the same as in Example 1. During vacuum ion plating, the target current was adjusted to 8A, the deposition time was shortened to 60 min, and the remaining conditions were the same as in Example 1. Finally, SiC@Al core-shell structure modified particles with a continuous, dense pure aluminum coating on the surface were obtained, with a thickness of 1.0 μm.

[0047] S2: Preparation of composite powder: During the batching process, the volume fraction of the SiC@Al core-shell structure modified particles was adjusted to 20%, and the mixing and drying steps were the same as in Example 1 to obtain a high volume fraction composite powder.

[0048] S3: Selective Laser Melting: The high volume fraction composite powder was placed in an SLM (Surface Mount Technology) device, and the printing process was performed using appropriate forming parameters matched to a volume fraction of 20%. The specific parameters were adjusted as follows: laser power of 300W, scanning speed of 1000mm / s, layer thickness of 25μm, scanning spacing of 0.10mm, and substrate preheating temperature of 140℃.

[0049] S4: Stress-relieving heat treatment: The heat treatment process was the same as in Example 1, and the final composite material was obtained.

[0050] Test results: The composite material prepared in this embodiment has a density of 98.2% and no obvious cracks or macroscopic defects.

[0051] Example 3 This embodiment provides a high-formability, high-volume-fraction SiC / AlSi10Mg composite material and its additive manufacturing method, specifically including the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: The pretreatment steps were the same as in Example 1. During vacuum ion plating, the target current was adjusted to 15A, the deposition time was extended to 120 min, and the remaining conditions were the same as in Example 1. Finally, SiC@Al core-shell modified particles with a continuous, dense pure aluminum coating on the surface were obtained, with a thickness of 2.0 μm.

[0052] S2: Preparation of composite powder: During the batching process, the volume fraction of the SiC@Al core-shell structure modified particles was adjusted to 30%, and the mixing and drying steps were the same as in Example 1 to obtain a high volume fraction composite powder.

[0053] S3: Selective Laser Melting: The high volume fraction composite powder was placed in an SLM (Silicon-Laser Processing) device, and the printing process was performed using appropriate forming parameters matched to a volume fraction of 30%. The specific parameters were adjusted as follows: laser power of 400W, scanning speed of 800mm / s, layer thickness of 35μm, scanning spacing of 0.14mm, and substrate preheating temperature of 170℃.

[0054] S4: Stress-relieving heat treatment: The heat treatment process was the same as in Example 1, and the final composite material was obtained.

[0055] Test results: The composite material prepared in this embodiment has a density of 98.8%, good forming, and no structural defects were found.

[0056] Comparative Example 1 This comparative example provides a silicon carbide particle-reinforced aluminum matrix composite material and its additive manufacturing method. The difference from Example 1 is that raw SiC particles without surface modification are directly mixed with AlSi10Mg powder.

[0057] Specifically: step S1 in Example 1 is omitted; unmodified raw SiC particles (volume fraction of 25%) are directly mixed with gas-atomized AlSi10Mg powder, and the mixing and drying conditions are the same as in Example 1; the subsequent selective laser melting forming parameters (laser power 350W, scanning speed 1200mm / s, etc.) and stress-relief heat treatment process are completely consistent with those in Example 1.

[0058] Test results: The comparative sample part exhibited significant macroscopic cracks on both the surface and interior, with a density of only 92%. Microstructural analysis revealed the formation of a large amount of brittle Al4C3 phase within the part, and the debonding and cracking at the interfaces led to a substantial decrease in the overall mechanical properties of the composite material.

[0059] To further verify the beneficial effects of the high formability and high volume fraction SiC / AlSi10Mg composite material provided by this invention, mechanical property tests and microstructure observations were conducted on the parts prepared in Example 1 (the modified system of this invention) and Comparative Example 1 (the unmodified system). The specific comparisons are as follows: Comparative analysis of mechanical properties: like Figure 1 As shown in (a) and (b), the tensile strength and elastic modulus of the composite material of Example 1 and Comparative Example 1 are compared.

[0060] Comparative Example 1, where the SiC particles were not modified by surface pure aluminum plating, showed a tensile strength of only 280 MPa and an elastic modulus of only 75 GPa. This is because the SiC particles, with a volume fraction as high as 25%, not only exhibited poor wettability with the matrix in their unmodified state, resulting in low density, but also failed to effectively buffer the significant difference in thermal expansion coefficients between them and the aluminum matrix. This led to a large number of microcracks within the material, causing a substantial deterioration in its mechanical properties.

[0061] In contrast, the composite material prepared using the method of this invention (Example 1) exhibits a tensile strength that jumps to 420 MPa and an elastic modulus that significantly increases to 110 GPa. This fully demonstrates that the 1.0~2.0 μm thick pure aluminum coating plays a crucial role in stress buffering and bridging. The pure aluminum coating effectively absorbs and releases the enormous thermal mismatch stress generated during the rapid thermal cycling of the laser, completely eliminating microcracks, thereby perfectly transforming the excellent high strength and high modulus characteristics of the high-content SiC particles into the overall macroscopic mechanical properties of the composite material.

[0062] Microstructure and Interface Analysis: like Figure 2As shown, in the microstructure of Comparative Example 1 (unmodified SiC system), a large number of coarse, needle-like precipitates are densely interwoven and dispersed around the SiC particles and throughout the aluminum matrix. Combined with the annotations in the figure and the material properties, these crisscrossing needle-like substances are typical hard and brittle Al4C3 phases. This clearly indicates that in the transient high-temperature molten pool of SLM forming, unprotected exposed SiC particles underwent extremely severe interfacial side reactions with the highly reactive aluminum melt (4Al + 3SiC = Al4C3 + 3Si). The formation of a large number of brittle phases not only excessively consumed the reinforcement but also severely disrupted the continuity of the aluminum matrix like a wedge, leading to extreme concentration of interfacial stress. This is direct microscopic evidence of the frequent macroscopic cracking and drastic deterioration of mechanical properties in the Comparative Example 1 part.

[0063] like Figure 3 As shown, the microstructure of Example 1 (the pure aluminum-coated modified SiC system of this invention) exhibits a distinctly superior morphology. Dark-colored SiC particles are uniformly distributed within a light-colored AlSi10Mg alloy matrix, with clear particle edges, complete morphology, clean and tight interfaces, and no traces of needle-like carbide (Al4C3) precipitation observed throughout the matrix. This strongly confirms that the pure aluminum physical barrier layer pre-constructed on the surface of SiC particles by vacuum ion plating, under the high-temperature penetration of selective laser melting, perfectly blocks the direct contact between the SiC core and the molten aluminum, fundamentally inhibiting the occurrence of harmful interfacial reactions. Simultaneously, due to the high compatibility between the pure aluminum coating and the matrix composition, excellent metallurgical fusion is achieved, ultimately successfully constructing a high-strength "dual-interface bonding" structure without brittle phase interference.

[0064] In summary, the comparison results of the above embodiments and comparative examples fully illustrate the core technical advantages and inherent working mechanism of the present invention. Unmodified high volume fraction SiC particles are difficult to overcome the extremely large thermal mismatch stress and severe interfacial side reactions in additive manufacturing, which inevitably leads to cracking and performance collapse of the parts. The core principle of the present invention is that: in the preparation method of the present invention, a continuous and dense pure aluminum coating with a thickness of 1.0~2.0μm is pre-constructed on the surface of SiC particles through vacuum ion plating, which cleverly forms a SiC@Al core-shell structure. In the extreme environment of the rapid thermal cycling of selective laser melting (SLM), the pure aluminum coating plays a crucial dual role. As a physical barrier layer, it blocks the direct contact between SiC and the high-temperature aluminum melt, prevents the formation of brittle Al4C3 phase, and ensures the purity of the interface and the metallurgical bonding strength. Furthermore, as a flexible buffer layer, it absorbs and releases the thermal mismatch stress caused by the huge difference in thermal expansion coefficients between the ceramic particles and the aluminum alloy matrix, eliminating the hidden dangers of microcracks and interface debonding. Furthermore, the introduction of a pure aluminum shell greatly improves the flowability and melt wettability of high-content ceramic powder. Combined with printing process parameters precisely matched for different volume fractions of 20% to 30%, the forming bottleneck of traditional additive manufacturing is finally broken through, and stable forming of high-volume-fraction SiC / AlSi10Mg composite materials with defects-free, high density (≥98.2%), and high strength and high modulus is successfully achieved.

[0065] In the description of the embodiments of the present invention, it should be noted that the terms "inner" and "outer" and other terms indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0066] In the description of this invention, the references to "one embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An additive manufacturing method for a high-formability, high-volume-fraction SiC / AlSi10Mg composite material, characterized in that, Includes the following steps: S1: Preparation of SiC@Al core-shell structure modified particles: SiC particles are pretreated, and then a pure aluminum coating is deposited on the surface of the SiC particles by vacuum ion plating to obtain SiC@Al core-shell structure modified particles with a continuous and dense pure aluminum coating on the surface. The thickness of the pure aluminum coating is 1.0~2.0μm. S2: Preparation of composite powder: The SiC@Al core-shell structure modified particles and gas-atomized AlSi10Mg powder are mixed, kneaded and dried according to the volume fraction ratio to obtain a high volume fraction composite powder, wherein the volume fraction of the SiC@Al core-shell structure modified particles in the high volume fraction composite powder is 20%~30%; S3: Selective laser melting: The high volume fraction composite powder is placed in a selective laser melting device, and the corresponding selective laser melting parameters are matched according to the volume fraction of the SiC@Al core-shell structure modified particles to form a composite material part. S4: Stress-relieving heat treatment: The composite material part is subjected to heat preservation and furnace cooling treatment to obtain a high formability, high volume fraction SiC / AlSi10Mg composite material.

2. The additive manufacturing method according to claim 1, characterized in that, In step S1, the pretreatment includes degreasing, acid pickling and roughening, sensitization and activation treatments performed sequentially.

3. The additive manufacturing method according to claim 2, characterized in that, The degreasing is performed by ultrasonic cleaning with acetone solution for 8-12 minutes; the acid pickling and roughening is performed by soaking in hydrofluoric acid solution with a mass fraction of 5%-15% for 3-7 minutes; the sensitization is performed by treatment with stannous chloride-hydrochloric acid solution for 3-5 minutes; and the activation is performed by treatment with silver nitrate-ammonia solution for 2-4 minutes.

4. The additive manufacturing method according to claim 1, characterized in that, In step S1, the parameters of the vacuum ion plating process include: A medium-purity aluminum target with a purity of not less than 99.9% is used; The vacuum degree is 3.0 × 10⁻⁶. -3 ~8.0×10 -3 Pa; The target current is 8~15A; The substrate bias voltage is -100 to -200V; The deposition time is 60-120 min; The deposition atmosphere is argon, and the flow rate of the argon is 20~40 sccm.

5. The additive manufacturing method according to claim 1, characterized in that, In step S2, the particle size of the gas-atomized AlSi10Mg powder is 15~45μm; The mixing process is carried out mechanically using a three-dimensional mixer, with a mixing time of 1.5 to 2.5 hours. The drying process is carried out in a vacuum drying oven at a temperature of 70-90°C for 3-5 hours.

6. The additive manufacturing method according to claim 1, characterized in that, In step S3, the selected area laser melting forming parameters include laser power, scanning speed, layer thickness, scanning spacing, and substrate preheating temperature. The laser power is 300~420W; The scanning speed is 700~1300 mm / s; The layer thickness is 25~35μm; The scanning interval is 0.10~0.14mm; The substrate preheating temperature is 140~170℃.

7. The additive manufacturing method according to claim 6, characterized in that, In step S3, the selected area laser melting forming parameters, based on the volume fraction of the SiC@Al core-shell structure modified particles, include: When the volume fraction of the SiC@Al core-shell modified particles is greater than or equal to 20% and less than or equal to 23.5%, the laser power is 300~360W, the scanning speed is 1000~1100mm / s, the layer thickness is 25~30μm, the scanning spacing is 0.10~0.12mm, and the substrate preheating temperature is 140~160℃; When the volume fraction of the SiC@Al core-shell structure modified particles is greater than 23.5% and less than or equal to 26.5%, the laser power is 340~360W, the scanning speed is 1100~1300mm / s, the layer thickness is 30μm, the scanning spacing is 0.12mm, and the substrate preheating temperature is 150℃. When the volume fraction of the SiC@Al core-shell structure modified particles is greater than 26.5% and less than or equal to 30%, the laser power is 380~420W, the scanning speed is 700~900mm / s, the layer thickness is 30~35μm, the scanning spacing is 0.12~0.14mm, and the substrate preheating temperature is 150~170℃.

8. The additive manufacturing method according to claim 1, characterized in that, In step S4, the heat preservation and furnace cooling process is as follows: heat preservation at 180~220℃ for 1.5~2.5h, followed by furnace cooling to room temperature.

9. A high-formability, high-volume-fraction SiC / AlSi10Mg composite material, characterized in that, It is prepared by the additive manufacturing method as described in any one of claims 1-8.

10. The high formability, high volume fraction SiC / AlSi10Mg composite material according to claim 9, characterized in that, The composite material includes an AlSi10Mg alloy matrix and SiC@Al core-shell structure modified particles dispersed in the AlSi10Mg alloy matrix. The volume fraction of the SiC@Al core-shell structure modified particles is 20%~30%, and the surface of the SiC@Al core-shell structure modified particles is coated with a pure aluminum coating with a thickness of 1.0~2.0μm.

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