A high-silicon aluminum alloy composite material based on spray forming and a preparation method thereof

Abstract

The application discloses a high-silicon aluminum alloy composite material based on spray forming and a preparation method thereof, and relates to the technical field of metal matrix composite material preparation. In the method, a high-silicon aluminum alloy melt is atomized and deposited in an inert atmosphere to obtain a deposition blank with fine and uniformly distributed reinforcing particles, the interface mismatch degree of the reinforcing particles and the primary Si and alpha-Al phases in the matrix is low, the bonding strength is high, and load stress can be effectively transmitted; then, the deposition blank is heat treated to obtain the high-silicon aluminum alloy composite material. In the application, the reinforcing phase is introduced in the form of VB2 / Al-Si intermediate alloy, the synergistic effect of the spray forming process and the heat treatment process is used to refine the primary Si and avoid the agglomeration of the reinforcing particles, and the preparation of the high-silicon aluminum alloy composite material with high performance is realized. The obtained material has uniform structure, good strength and toughness matching, low thermal expansion coefficient, high wear resistance, good shock resistance and heat processing adaptability, and is suitable for high-end structural parts with the synergistic requirements of strength and toughness, wear resistance and formability.

Description

Technical Field

[0001] This invention relates to a high-silicon aluminum alloy composite material based on spray forming and its preparation method, belonging to the field of metal matrix composite material preparation technology. Background Technology

[0002] Hypereutectic Al-Si alloys, especially high-silicon aluminum alloys with Si content ≥20%, have broad application prospects in wear-resistant parts such as pistons, swashplates, and brake discs in automotive engines due to their high hardness, low coefficient of thermal expansion, and excellent wear resistance. Their performance largely depends on the size, morphology, and distribution of the primary Si phase; however, the primary Si phase obtained by traditional casting methods is usually coarse (up to tens of micrometers), sharp in morphology, and unevenly distributed, becoming stress concentration points and severely deteriorating the alloy's mechanical and machinability.

[0003] To improve this situation, introducing high-hardness, high-stability ceramic particles as reinforcing phases is one effective approach. Among them, ceramic refining agents such as VB2, TiB2, TiC, ZrB2, Al2O3, ZrO2, ZrC, SiC, and AlN can not only directly improve the matrix strength and wear resistance through load transfer and dispersion strengthening, but their fine particles can also act as a heterogeneous nucleation substrate during solidification, further refining the primary Si phase and achieving the dual effects of "reinforcement" and "refinement." While traditional stirred casting can prepare such particle-reinforced Al-Si composites, it easily introduces porosity and inclusions, and the particles are prone to agglomeration and segregation, making uniform distribution difficult. Furthermore, prolonged melt treatment at high temperatures can cause the reinforcing particles to react with the melt to form brittle phases, deteriorating interfacial bonding and leading to problems such as cracking and difficulty in deformation during hot working of high-silicon aluminum alloys. Summary of the Invention

[0004] To address the shortcomings of traditional casting methods in preparing high-silicon aluminum alloys, such as coarse primary Si phases, uneven distribution of reinforcing particles, and susceptibility to interface problems, resulting in poor hot workability, this invention provides a high-silicon aluminum alloy composite material based on spray forming and its preparation method. The core of this invention lies in the synergistic effect of specific raw material selection (using an intermediate alloy synthesized in situ to introduce reinforcing particles) and optimized spray forming and subsequent processing parameters. This leverages the rapid solidification advantage of spray forming while ensuring efficient introduction and uniform dispersion of reinforcing particles, as well as the formation of a strong and tough interface with the matrix. The result is a high-performance composite material with fine and uniform microstructure, excellent strength and toughness, and ease of hot forming.

[0005] One objective of this invention is to provide a method for preparing high-silicon aluminum alloy composite materials based on spray forming, specifically including the following steps: (1) Weigh industrial pure aluminum, metallic silicon, Al-50Cu master alloy and VB2 / Al-6Si master alloy raw materials according to the mass ratio of the chemical formula of high silicon aluminum alloy composite material xVB2 / Al-ySi-zCu. Mix the raw materials and melt them to obtain alloy melt.

[0006] (2) The alloy melt is heated to a temperature higher than the melting point and then sprayed. The droplets obtained by spraying are deposited on a pre-placed substrate to form a deposited blank.

[0007] (3) The deposited billet is solution treated, then quenched (preferably in water at 50~60℃), and then aged to obtain a high silicon aluminum alloy composite material.

[0008] Preferably, in step (1), the purity of industrial pure aluminum is ≥99.9% by mass percentage, and the purity of metallic silicon is ≥99.9% by mass percentage.

[0009] Preferably, the VB2 content in the VB2 / Al-6Si master alloy in step (1) is 11% by mass; the VB2 / Al-6Si master alloy is synthesized in situ by a melt reaction method from a mixture of industrial salts containing V (such as potassium fluorovanadate K2VF6) and industrial salts containing B (such as potassium fluoroborate KBF4).

[0010] More preferably, the preparation method of the VB2 / Al-6Si master alloy in step (1) is as follows: K2VF6 powder and KBF4 powder are mixed in a 1:1 mass ratio in a planetary ball mill. The milling jar and milling media are made of zirconium oxide. The ball-to-powder ratio is 5:1, the milling speed is 300-400 rpm, and the milling time is 1.5-2 h. Milling is carried out under an argon protective atmosphere to obtain a uniformly mixed powder. The mixed powder is dehydrated at 180-200℃ for 1.5-2 h to obtain a dehydrated mixed salt powder. Industrial pure Al and industrial pure Si are heated and melted at 820-850℃ to obtain an Al-6Si melt. The dehydrated mixed salt powder is introduced into the bottom of the Al-6Si melt, and argon is introduced as a protective gas to prevent melting. The mixture is oxidized and rapidly mechanically stirred with a graphite stirring rod at 830-850℃ for 30-60 minutes at a speed of 500-700 rpm to allow the mixed salt powder to react completely in the melt and form VB2 particles, resulting in mixed melt A. Then, hexachloroethane (C2Cl6) refining agent is added, and the mixture is refined at 720-750℃ for 8-15 minutes to obtain mixed melt B. The content of C2Cl6 refining agent in mixed melt B is 0.5%-1.0% by mass. During refining, the mixture is stirred slowly, and after standing for 5-10 minutes, the scum is skimmed off to obtain the refined melt. When the temperature of the refined melt drops to 700-720℃, it is poured into a graphite mold preheated to 250-300℃ and cast to obtain the VB2 / Al-6Si master alloy. The overall in-situ reaction equation for the VB2 / Al-6Si master alloy can be expressed as: Preferably, the chemical formula of the high silicon aluminum alloy composite material in step (1) is xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu, respectively, and the balance is Al, and 2%≤x≤4%, y≥20%, and 4%≤z≤5%.

[0011] Preferably, the melting conditions in step (1) are: melting at 750℃~800℃ for 60min~90min.

[0012] Preferably, the conditions for spray forming in step (2) are: melt temperature 850℃~870℃, spray medium is inert gas (such as high-purity nitrogen), inert gas flow rate 2.0kg / min~2.5kg / min, gas pressure 0.4MPa~0.45MPa, and spray forming time 30s~60s.

[0013] More preferably, the substrate pre-placed in step (2) is a copper substrate.

[0014] Preferably, the solution treatment conditions in step (3) are: heat treatment at 480℃~520℃ for 8h~10h; the aging treatment conditions are: heat treatment at 160℃~180℃ for 7h~9h.

[0015] Another objective of this invention is to provide a high-silicon aluminum alloy composite material prepared by the method of this invention.

[0016] Mechanism of the invention: This invention introduces a reinforcing phase through in-situ synthesis of a VB2 / Al-Si master alloy. By leveraging the synergistic effects of spray forming process parameters and solution / aging processes, a high-performance, high-silicon aluminum alloy composite material is prepared. This solves the problems of particle agglomeration and wettability, laying the foundation for uniform distribution. At extremely high cooling rates, the growth of the primary Si phase is suppressed, and VB2 particle segregation is prevented, resulting in a finely dispersed microstructure of both the reinforcing phase and primary Si. This fully activates matrix strengthening while avoiding microstructure coarsening. The synergistic system of this invention constructs a semi-coherent interface structure with strong interfacial bonding and small VB2 particles (≤8μm), thereby improving the material's hardness (≥2.1GPa), thermoplastic deformation capacity, and wear resistance.

[0017] The beneficial effects of this invention are: (1) Microstructure refinement and silicon phase nucleation control: The extremely high cooling rate of spray forming significantly inhibits the growth of the primary Si phase, promotes uniform nucleation of the Si phase through solidification kinetic regulation, and improves the plasticity of the matrix; thus refining its average size from more than ten micrometers in the as-cast state to 7~8 μm. At the same time, VB2 particles are captured by the rapidly solidified matrix, achieving a uniform dispersion distribution at the nano / submicron scale, avoiding the agglomeration phenomenon in traditional processes.

[0018] (2) Constructing a strong semi-coherent interface: Transmission electron microscopy analysis confirmed that semi-coherent interfaces were formed between VB2 particles, α-Al matrix and primary Si phase. This low-energy and stable interface structure not only reduced the nucleation barrier and promoted heterogeneous nucleation, but also, due to its high structural stability, effectively coordinated the local strain near the interface during thermal deformation, delaying the initiation and propagation of microcracks.

[0019] (3) Excellent plastic deformation capacity and hot working adaptability: Due to the rapid solidification effect unique to the spray forming process, the primary Si phase is significantly refined and the morphology tends to be round, which effectively avoids the stress concentration and fragmentation tendency of coarse and sharp Si phases during the deformation process; at the same time, the dispersed VB2 reinforcing phase forms a stable interface bond with the matrix, which can effectively suppress grain boundary migration and abnormal grain growth during hot deformation, promote the uniform refinement of dynamic recrystallization structure, and enable the material to exhibit coordinated and stable plastic rheological capacity and excellent high-temperature structural stability within a wide hot working window, providing an ideal material basis for the near-net-shape forming of wear-resistant components with complex shapes.

[0020] (4) Significantly improved hardness and wear resistance: This invention introduces VB2 through in-situ synthesis, which significantly improves the microhardness of the composite material. In the friction and wear test, the composite material exhibits a low coefficient of friction and wear depth under a 15N load; its wear mechanism is slight plowing and fatigue wear, and its wear resistance is significantly enhanced.

[0021] (5) Short process flow and low energy consumption: The present invention adopts near-net-shape spray deposition, combined with heat treatment, which avoids the complicated powder making, sieving, cold pressing and sintering processes of traditional powder metallurgy, shortens the process flow and reduces energy consumption and production costs. Attached Figure Description

[0022] Figure 1 Figure 1 shows the metallographic structure of the composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is the high silicon aluminum alloy composite material prepared in Example 1; (b) is the high silicon aluminum alloy composite material prepared in Example 2; and (c) is the Al-20Si-5Cu matrix alloy prepared in Comparative Example 1.

[0023] Figure 2 Figure 1 shows SEM images of the composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is the high silicon aluminum alloy composite material prepared in Example 1; and Figure (b) is the high silicon aluminum alloy composite material prepared in Comparative Example 2.

[0024] Figure 3 This is a TEM image of the product shown in Embodiment 1 of the present invention.

[0025] Figure 4 These are comparison charts of the compression of composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is a comparison chart of the compression of the composite material prepared in Comparative Example 1 (left) and Example 1 (right) at 30% compression, and (b) is a comparison chart of the compression of the composite material prepared in Comparative Example 2 (left) and Example 1 (right) at 60% compression.

[0026] Figure 5Figure 1 shows the microhardness diagrams of the composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is the high silicon aluminum alloy composite material prepared in Example 1; (b) is the high silicon aluminum alloy composite material prepared in Example 2; and (c) is the Al-20Si-5Cu matrix alloy prepared in Comparative Example 1.

[0027] Figure 6 Figure 1 shows the wear depth of the composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is the high silicon aluminum alloy composite material prepared in Example 1; (b) is the high silicon aluminum alloy composite material prepared in Example 2; and (c) is the Al-20Si-5Cu matrix alloy prepared in Comparative Example 1.

[0028] Figure 7 Figure 1 shows SEM images of the worn surfaces of the composite materials prepared in the embodiments and comparative examples of the present invention; wherein: Figure (a) is the high silicon aluminum alloy composite material prepared in Example 1; (b) is the high silicon aluminum alloy composite material prepared in Example 2; and (c) is the Al-20Si-5Cu matrix alloy prepared in Comparative Example 1. Detailed Implementation

[0029] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments. In the embodiments and comparative examples of this invention, unless otherwise specified, all chemical reagents used were commercially available analytical grade reagents. The industrial pure aluminum and metallic silicon used in the embodiments and comparative examples of this invention have a purity of 99.9% by mass percentage, and all proportions in the embodiments and comparative examples are mass percentages.

[0030] Example 1 A method for preparing a high-silicon aluminum alloy composite material based on spray forming specifically includes the following steps: (1) According to the chemical formula of the high-silicon aluminum alloy composite material xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu respectively, and the balance is Al, and x is 2%; y is 20%; z is 5%, industrial pure aluminum, metallic silicon, Al-50Cu master alloy and VB2 / Al-6Si master alloy raw materials are weighed and melted in an electric resistance furnace at 800℃ for 60 min to obtain a uniform alloy melt; among which VB2 / Al-6Si master alloy The VB2 content is 11% by mass. The preparation method of the VB2 / Al-6Si master alloy is as follows: in-situ synthesis is carried out by melt reaction method. K2VF6 powder and KBF4 powder are mixed by mechanical ball milling in a planetary ball mill at a mass ratio of 1:1. The ball mill jar and milling media are made of zirconium oxide. The ball-to-powder ratio is 5:1, the ball milling speed is 300 rpm, and the ball milling time is 1.5 h. Ball milling is carried out under an argon protective atmosphere to obtain a uniformly mixed powder. The mixed powder was dehydrated at 180℃ for 1.5 hours to obtain dehydrated mixed salt powder. Industrial pure Al and industrial pure Si were heated and melted at 820℃ in a specific ratio to obtain Al-6Si melt. The dehydrated mixed salt powder was introduced into the bottom of the Al-6Si melt, with argon gas introduced as a protective gas to prevent oxidation. Rapid mechanical stirring was performed at 830℃ using a graphite stirring rod at a speed of 500 rpm for 30 minutes to ensure complete reaction of the mixed salt powder in the melt. VB2 particles were generated to obtain mixed melt A; then C2Cl6 refining agent was added, and the mixture was refined at 720℃ for 8 minutes to obtain mixed melt B, wherein the content of C2Cl6 refining agent in mixed melt B was 0.5% by mass percentage. During the refining process, the mixture was stirred slowly, and after standing for 5 minutes, the scum was skimmed off to obtain the refined melt; when the temperature of the refined melt dropped to 700℃, it was poured into a graphite mold preheated to 250℃ and cast to obtain VB2 / Al-6Si master alloy.

[0031] (2) Stabilize the melt temperature at 850℃~870℃ and start the spray forming equipment; the melt flows out through the guide pipe and is atomized into fine droplets by 0.45MPa high-purity nitrogen gas, which is sprayed onto the rotating copper substrate. The high-purity nitrogen gas flow rate is 2.5kg / min and the spray forming time is 45s, forming a deposit blank with a thickness of about 36mm.

[0032] (3) The deposited billet is placed in a muffle furnace and subjected to a solution treatment at 520°C for 9 hours. Then it is quickly quenched in warm water at 50°C. After the sample is cooled, it is subjected to an artificial aging treatment at 170°C for 8 hours. Then it is air-cooled to room temperature to obtain the high silicon aluminum alloy composite material.

[0033] Metallographic testing was performed on the composite material prepared in this embodiment, and the metallographic structure is shown in the figure below. Figure 1 As shown in (a), the primary Si phase in the composite material is significantly refined after using the spray forming process and adding VB2. The average size is approximately 7.74 μm, exhibiting a fine polygonal shape and uniform distribution, with no obvious coarse plate-like Si phase observed. The introduction of VB2 particles further promotes heterogeneous nucleation and solidification inhibition, refining the microstructure. From the SEM image (… Figure 2 (a) and the surface scan results show that VB2 particles are diffusely distributed in the matrix without obvious agglomeration, indicating that the process effectively achieved good dispersion of the reinforcing phase. TEM image ( Figure 3 Further analysis shows that VB2 particles form a semi-coherent interface with the α-Al matrix and primary Si, exhibiting good interfacial bonding, which is beneficial for load transfer and strengthening. This material demonstrates excellent thermoplasticity in hot compression tests. Figure 4 No cracking occurred under 60% compression, indicating good hot working adaptability. Microhardness test results ( Figure 5 (a) shows that its hardness reaches 2.1 ± 0.47 GPa, significantly higher than that of the unreinforced sample. Friction and wear test ( Figure 6 (a) and Figure 7 (a) indicates that it has a low wear depth under a 15N load, and the wear surface is mainly characterized by slight plowing and fatigue wear, exhibiting excellent wear resistance. Its wear mechanism is mainly fatigue wear, accompanied by a certain amount of abrasive wear and adhesive wear.

[0034] In this embodiment, a reinforcing phase is introduced in the form of VB2 / Al-Si master alloy. Through the synergistic effect of spray forming process parameters and solid solution and aging processes, a VB2 particle and semi-coherent interface structure with strong interfacial bonding and small size is constructed in the material, thereby improving the material's hardness, thermoplastic deformation capacity and wear resistance.

[0035] Example 2 A method for preparing a high-silicon aluminum alloy composite material based on spray forming specifically includes the following steps: (1) According to the chemical formula of the high-silicon aluminum alloy composite material xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu respectively, and the balance is Al, and x is 3%; y is 22%; z is 4%, industrial pure aluminum, metallic silicon, Al-50Cu master alloy and VB2 / Al-6Si master alloy raw materials are weighed and melted in an electric resistance furnace at 750℃ for 90 min to obtain a uniform alloy melt; among which VB2 / Al-6Si master alloy The VB2 content is 11% by mass. The preparation method of the VB2 / Al-6Si master alloy is as follows: in-situ synthesis is carried out by melt reaction method. K2VF6 powder and KBF4 powder are mixed by mechanical ball milling in a planetary ball mill at a mass ratio of 1:1. The ball mill jar and grinding media are made of zirconium oxide. The ball-to-powder ratio is 5:1, the ball milling speed is 350 rpm, and the ball milling time is 1.8 h. Ball milling is carried out under an argon protective atmosphere to obtain a uniformly mixed powder. The mixed salt powder was dehydrated at 190℃ for 1.8 hours to obtain dehydrated mixed salt powder. Industrial pure Al and industrial pure Si were heated and melted at 830℃ to obtain Al-6Si melt. The dehydrated mixed salt powder was introduced into the bottom of the Al-6Si melt, with argon gas introduced as a protective gas to prevent oxidation. Rapid mechanical stirring was performed at 840℃ using a graphite stirring rod at a speed of 600 rpm for 40 minutes to ensure complete reaction of the mixed salt powder in the melt. VB2 particles were formed to obtain mixed melt A. Then, C2Cl6 refining agent was added, and the mixture was refined at 740°C for 12 minutes to obtain mixed melt B. The content of C2Cl6 refining agent in mixed melt B was 0.8% by mass. During the refining process, the mixture was slowly stirred, and after standing for 8 minutes, the scum was skimmed off to obtain the refined melt. When the temperature of the refined melt dropped to 720°C, it was poured into a graphite mold preheated to 280°C and cast to obtain the VB2 / Al-6Si master alloy. The same spray forming process as in Example 1 was used, except that the gas flow rate was 2.3 kg / min, the gas pressure was 0.43 MPa, and the time was 30 s, forming a deposited blank with a thickness of approximately 30 mm.

[0036] (2) The deposited billet was placed in a muffle furnace and subjected to a solution treatment at 480°C for 10 hours. Then it was quickly quenched in warm water at 60°C. After the sample cooled, it was subjected to an artificial aging treatment at 160°C for 7 hours. Then it was air-cooled to room temperature to obtain the high silicon aluminum alloy composite material.

[0037] Metallographic testing was performed on the composite material prepared in this embodiment, and its metallographic structure is as follows: Figure 1As shown in (b), it can be seen that with increased Si content and the addition of VB2, the number of primary Si phases in the composite material increases significantly, but their size remains relatively small, with an average size of approximately 7-8 μm. The morphology is mainly small blocky or approximately polygonal, with no obvious coarse lamellar Si phases, and the overall distribution is relatively uniform. This indicates that under high silicon content conditions, VB2 particles can still effectively play a role in heterogeneous nucleation and solidification inhibition, suppressing the abnormal growth of the primary Si phase. SEM morphology observation and elemental surface scanning analysis show that VB2 particles are relatively uniformly distributed in the aluminum matrix, with no obvious agglomeration or segregation observed. TEM observation results show that VB2 particles form an interfacial bond structure with the α-Al matrix and the primary Si phase, with good interfacial continuity and no obvious interfacial debonding or crack defects. Hot compression test results show that under 60% compression deformation, the sample did not exhibit macroscopic cracking, and the overall material structure remained intact. Microhardness test results are shown below. Figure 5 As shown in (b), its hardness reaches 2.37 ± 0.31 GPa, significantly higher than that of low-silicon or unreinforced samples. This is mainly attributed to the combined strengthening effect brought about by the high volume fraction of primary Si phase and the dispersed VB2 particles. In the tribological test ( Figure 6 (b) and Figure 7 (b) The material exhibits a low coefficient of friction and wear depth under a 15N load. The wear surface is mainly characterized by slight fatigue wear and localized adhesive wear. No severe ploughing or spalling was observed, indicating that it has excellent wear resistance.

[0038] In summary, under conditions of high silicon content, this embodiment successfully constructed a structure with fine and uniform primary Si phase and dispersed VB2 reinforcing phase through the synergistic effect of VB2 addition amount and spray forming and heat treatment process parameters (solution and aging), enabling the material to maintain high hardness while also having good wear resistance and structural stability.

[0039] Example 3 A method for preparing a high-silicon aluminum alloy composite material based on spray forming specifically includes the following steps: (1) According to the chemical formula of the high-silicon aluminum alloy composite material xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu respectively, and the balance is Al, and x is 4%; y is 20%; z is 4.5%, industrial pure aluminum, metallic silicon, Al-Cu50 master alloy and VB2 / Al-6Si master alloy raw materials are weighed and melted in an electric resistance furnace at 780℃ for 80 min to obtain a uniform alloy melt; among which VB2 / Al-6Si master alloy... The VB2 content in the alloy is 11% by mass. The preparation method of the VB2 / Al-6Si master alloy is as follows: in-situ synthesis is carried out by melt reaction method. K2VF6 powder and KBF4 powder are mixed mechanically by ball milling in a planetary ball mill at a mass ratio of 1:1. The ball mill jar and grinding media are made of zirconium oxide. The ball-to-powder ratio is 5:1, the ball milling speed is 400 rpm, and the ball milling time is 2 hours. Ball milling is carried out under an argon protective atmosphere to obtain a uniformly mixed powder. The mixed powder was dehydrated at 200℃ for 2 hours to obtain dehydrated mixed salt powder. Industrial pure Al and industrial pure Si were heated and melted at 850℃ in a specific ratio to obtain Al-6Si melt. The dehydrated mixed salt powder was introduced into the bottom of the Al-6Si melt, with argon gas introduced as a protective gas to prevent oxidation. Rapid mechanical stirring was performed at 850℃ using a graphite impeller at a speed of 700 rpm for 60 minutes to ensure complete reaction of the mixed salt powder in the melt. VB2 particles were used to obtain a mixed melt A. Subsequently, C2Cl6 refining agent was added, and the mixture was refined at 750°C for 15 minutes to obtain mixed melt B. The content of C2Cl6 refining agent in mixed melt B was 1.0% by mass. During the refining process, the mixture was slowly stirred, and after standing for 10 minutes, the scum was skimmed off to obtain the refined melt. When the temperature of the refined melt dropped to 710°C, it was poured into a graphite mold preheated to 300°C and cast to obtain the VB2 / Al-6Si master alloy. The same spray forming process as in Example 1 was used, except that the gas flow rate was 2.0 kg / min, the gas pressure was 0.4 MPa, and the time was 60 s, forming a deposited blank with a thickness of approximately 40 mm.

[0040] (2) The deposited billet is placed in a muffle furnace and subjected to a solution treatment at 500°C for 8 hours. Then it is quickly quenched in warm water at 55°C. After the sample is cooled, it is subjected to an artificial aging treatment at 180°C for 9 hours. Then it is air-cooled to room temperature to obtain the high silicon aluminum alloy composite material.

[0041] Metallographic testing of the composite material prepared in this embodiment showed that, even with increased VB2 content, the primary Si phase maintained a relatively small size, with an average size of approximately 7.59 μm. The morphology tended towards rounded and blunt shapes, and the distribution was relatively uniform, with no obvious coarse or sharp silicon phases observed. This indicates that higher VB2 content has a continuous refining and growth-inhibiting effect on the primary Si phase. With further increases in VB2 content, the spacing between some reinforcing particles decreased, and the particle density increased in local areas, which to some extent improved the interface constraint effect. SEM morphology and elemental distribution analysis showed that the reinforcing particles were relatively stable in the matrix, with no obvious large-scale aggregation regions observed. TEM results indicated a continuous interface structure between the reinforcing phase, the α-Al matrix, and the primary Si phase, with a clear interface transition zone and no obvious debonding or crack defects. Hot compression tests showed that under 60% compression deformation, the sample remained intact without macroscopic fracture, indicating that the material could withstand significant plastic deformation under these composition and heat treatment parameters. Microhardness testing showed a hardness of 2.15 ± 0.55 GPa. The results of friction and wear tests show that the friction coefficient and wear depth of the material remain at a low level under a load of 15N. The wear surface mainly exhibits slight plowing and fatigue spalling characteristics, without serious brittle fracture or large-area spalling. Its wear mechanism is still mainly fatigue wear, accompanied by a small amount of abrasive wear and adhesive wear.

[0042] This embodiment achieves a fine distribution of the primary Si phase through matched control of spray forming and subsequent heat treatment processes, while simultaneously reducing interparticle spacing and stabilizing the interface structure. The resulting composite material maintains a high level of hardness while exhibiting good microstructural stability and wear resistance, indicating that the overall performance of the material within this composition range is relatively balanced.

[0043] Comparative Example 1 A method for preparing an Al-20Si-5Cu matrix alloy specifically includes the following steps: The Al-20Si-5Cu matrix alloy without VB2 was prepared by weighing industrial pure aluminum, metallic silicon, and Al-50Cu master alloy raw materials in proportion and melting them in a resistance furnace at 800°C for 60 minutes to obtain a uniform alloy melt. The Al-20Si-5Cu matrix alloy was prepared by using the same spray forming and subsequent heat treatment process as in Example 1.

[0044] Metallographic analysis was performed on the Al-20Si-5Cu matrix alloy prepared in this comparative example, and its microstructure is as follows: Figure 1As shown in (c), it can be seen that under the condition of using only the spray forming process without adding the VB2 reinforcing phase, although the primary Si phase is more refined than the traditional as-cast structure, its average size is about 9.13 μm, which is significantly larger than that of the VB2 reinforced sample. Furthermore, some Si phases exhibit irregular plate-like or angular morphologies with poor distribution uniformity. SEM morphology and elemental surface scan results show that the primary Si phase is large in size and irregular in morphology, exhibiting plate-like or angular distribution. There is obvious elemental segregation in local areas, indicating that this comparative sample has insufficient heterogeneous nucleation and limited microstructure control during solidification. TEM observation further shows that the dislocation distribution in the matrix is ​​uneven, and there is a small amount of strain concentration in the interface bonding area. No obvious nano-precipitated strengthening structure is formed, indicating that the microstructure refinement and interface optimization effects are weak under this process condition. In the hot compression test ( Figure 4 (a) Left), this material is prone to cracking under large compression, indicating that the coarse and sharp primary Si phases easily induce stress concentration during deformation, limiting the material's adaptability to hot working. Microhardness test results are as follows: Figure 5 As shown in (c), its hardness is 1.76 ± 0.61 GPa, significantly lower than that of the VB2 reinforced composite material. Friction and wear test results ( Figure 6 (c) and Figure 7 (c) shows that the material has a large wear depth, and wide and deep furrows and obvious spalling pits can be observed on the wear surface. Its wear mechanism is mainly abrasive wear and brittle spalling, and its wear resistance is poor.

[0045] The above results indicate that although spray forming can refine the microstructure to some extent, it lacks the synergistic effect of VB2-type heterogeneous nucleating particles, making it difficult to obtain high-performance high-silicon aluminum alloy composite materials.

[0046] Comparative Example 2 A method for preparing a high-silicon aluminum alloy composite material based on spray forming specifically includes the following steps: According to the chemical formula of the high-silicon aluminum alloy composite material, xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu, respectively, and the balance is Al, and x is 5%, y is 20%, and z is 5%, industrial pure aluminum, metallic silicon, Al-50Cu master alloy, and VB2 / Al-6Si master alloy raw materials are weighed. The preparation method of VB2 / Al-6Si master alloy is the same as in Example 1, which is to melt it in a resistance furnace at 800°C for 60 min to obtain a uniform alloy melt. The high-silicon aluminum alloy composite material is prepared by using the same spray forming and subsequent heat treatment process as in Example 1.

[0047] Metallographic analysis of the composite material prepared in this comparative example showed that as the VB2 content increased, the size of the primary Si phase became further refined, with an average size of approximately 6.58 μm. This indicates that high VB2 content has a stronger ability to inhibit heterogeneous nucleation and solidification of the primary Si phase. SEM morphology and elemental distribution results ( Figure 2 (b) It can be observed that V element exhibits significant enrichment in local areas, indicating that VB2 particles begin to agglomerate under high addition conditions. This agglomeration not only weakens the effective dispersion strengthening effect of the reinforcing particles but also forms stress concentration sources in local areas. TEM observation shows that the interface between VB2 particles and the aluminum matrix is ​​relatively tight, but particle agglomeration is visible in local enrichment areas, and a certain density of dislocation entanglement structure exists near the interface. The strain distribution around the agglomeration area is uneven, which easily forms microcrack initiation sources. In the hot compression test ( Figure 4 (b) Left), the material showed obvious cracking under large compression, indicating that particle agglomeration and interfacial stress concentration weakened the material's ability to coordinate plastic deformation.

[0048] Its microhardness was 2.09±0.85 GPa, which did not increase significantly with increasing VB2 content. Tribological tests also showed that the wear depth and wear morphology of the material did not show further improvement, and its wear resistance was limited. The wear mechanism was still mainly fatigue wear, but accompanied by local spalling and adhesive wear.

[0049] Therefore, the introduction of excessive VB2 can easily cause particle aggregation, weakening interface coordination and overall performance, indicating that there is an upper limit to the VB2 content, which needs to be optimized within a reasonable range.

[0050] Comparative Example 3 The deposited billet was prepared using the same proportions and conditions as in Example 1. The deposited billet was then placed in a muffle furnace and subjected to solution treatment at 450°C for 6 hours. Subsequently, it was rapidly quenched in warm water at 55°C. After the sample cooled, it was subjected to artificial aging treatment at 150°C for 6 hours. Finally, it was air-cooled to room temperature to obtain the high-silicon aluminum alloy composite material.

[0051] Metallographic testing of the composite material prepared in this comparative example revealed that the overall size of the primary Si phase was significantly larger than that of the example, and coarsening of the silicon phase was observed in local areas, with decreased uniformity of distribution. This is mainly related to the lower solution temperature and insufficient holding time, resulting in incomplete dissolution of the second phase in the alloy and limiting the subsequent aging strengthening effect.

[0052] SEM observations showed that although VB2 particles were still distributed in the matrix, there were signs of localized stress concentration near the interface. Further TEM observations revealed that the number of reinforcing phases precipitated in the matrix was small, their size was relatively large and their distribution was uneven, and they did not form a diffuse and fine nanoscale precipitate structure. At the same time, there were dislocation stacking and localized lattice distortion at the interface between VB2 particles and the matrix, indicating a weak ability of the interface to coordinate deformation.

[0053] Its microhardness is 1.84±0.62 GPa, which is significantly lower than that of the example sample under optimized heat treatment conditions. Tribological test results show that the material has a large wear depth, and the wear surface shows obvious ploughing and spalling characteristics. The wear mechanism is mainly abrasive wear and fatigue spalling.

[0054] The above results indicate that the solution treatment and aging process parameters after spray forming have a significant impact on the microstructure stability and overall performance. Inappropriate heat treatment process parameters (low solution temperature and holding time) will weaken the VB2 reinforcement effect.

[0055] Comparative Example 4 The deposited billet was prepared using the same proportions and conditions as in Example 1. The deposited billet was then placed in a muffle furnace and subjected to solution treatment at 535°C for 12 hours. Subsequently, it was rapidly quenched in warm water at 55°C. After the sample cooled, it was subjected to artificial aging treatment at 200°C for 10 hours. Finally, it was air-cooled to room temperature to obtain the high-silicon aluminum alloy composite material.

[0056] Metallographic observation of the composite material prepared in this comparative example revealed that excessively high solution temperature and prolonged holding time led to coarsening of some primary Si phases, and localized heterogeneous microstructure. SEM morphology and elemental distribution results showed that the excessively high solution temperature and prolonged holding time resulted in coarsening of some primary Si phases, decreased microstructure uniformity, and significant compositional segregation in localized areas. Further TEM observation revealed a reduction in the number and uneven size distribution of precipitated phases in the matrix, the absence of a dispersed and fine reinforcing phase structure, and a certain degree of lattice distortion and dislocation stacking at the interface, indicating that excessive heat treatment weakened the microstructure stability.

[0057] Its microhardness is 1.93±0.27 GPa, which is higher than that of the unreinforced sample, but still relatively low. Tribological tests show that the material has a large wear depth, and the wear surface is mainly characterized by fatigue wear and localized spalling, indicating that its wear resistance is not fully utilized.

[0058] This indicates that excessive heat treatment (too high a solution temperature and too long a holding time) will damage the refined microstructure and stable interface structure formed by spray forming, thereby weakening the overall performance of the material.

[0059] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a high-silicon aluminum alloy composite material based on spray forming, characterized in that, Includes the following steps: (1) Weigh industrial pure aluminum, metallic silicon, Al-50Cu master alloy and VB2 / Al-6Si master alloy raw materials according to the mass ratio of the chemical formula of high silicon aluminum alloy composite material xVB2 / Al-ySi-zCu. Mix the raw materials and melt them to obtain alloy melt. (2) The alloy melt is heated to a temperature higher than the melting point and then sprayed. The droplets obtained by spraying are deposited on a pre-placed substrate to form a deposited blank. (3) The deposited billet is subjected to solution treatment, followed by quenching and then aging treatment to obtain a high silicon aluminum alloy composite material.

2. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, In step (1), the purity of industrial pure aluminum is ≥99.9% by mass percentage, and the purity of metallic silicon is ≥99.9% by mass percentage.

3. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, In step (1), the content of VB2 in the VB2 / Al-6Si master alloy is 11% by mass; the VB2 / Al-6Si master alloy is synthesized in situ by a melt reaction method using industrial salt containing V and industrial salt containing B.

4. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, The chemical formula of the high silicon aluminum alloy composite material in step (1) is xVB2 / Al-ySi-zCu, where x, y, and z represent the mass percentage content of VB2, Si, and Cu, respectively, with the balance being Al, and 2%≤x≤4%, y≥20%, and 4%≤z≤5%.

5. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, The melting conditions in step (1) are: melting at 750℃~800℃ for 60min~90min.

6. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, The conditions for spray forming in step (2) are: melt temperature 850℃~870℃, spray medium is inert gas, inert gas flow rate is 2.0kg / min~2.5kg / min, gas pressure is 0.4MPa~0.45MPa, and spray forming time is 30s~60s.

7. The method for preparing high-silicon aluminum alloy composite materials based on spray forming according to claim 1, characterized in that, The conditions for solution treatment in step (3) are: heat treatment at 480℃~520℃ for 8h~10h; the conditions for aging treatment are: heat treatment at 160℃~180℃ for 7h~9h.

8. The high-silicon aluminum alloy composite material prepared by the method according to any one of claims 1 to 7.

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