High-modulus and high-strength aluminum-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of metal-based composite materials, in particular to a high-modulus and high-strength aluminum-based composite material and a preparation method thereof.The high-modulus and high-strength aluminum-based composite material comprises aluminum alloy matrix powder and reinforced phase particles; the aluminum alloy matrix powder comprises Mg, Si, Mn, Sc, Zr and the balance Al and inevitable impurities. The reinforced phase particles comprise TiN nanoparticles and SiN nanoparticles; the preparation method comprises the following steps: uniformly mixing aluminum alloy matrix powder and reinforced phase particles by adopting a ball milling process to obtain an aluminum-based composite powder mixture; performing a forming experiment on the mixture through a selective laser melting process to obtain a sample material; and finally, the sample material is directly subjected to aging heat treatment, and the aluminum-based composite material is obtained. The high-modulus and high-strength aluminum-based composite material not only has excellent forming performance, but also has excellent mechanical properties, and can meet the requirements of the fields of aerospace, automobiles, ships and the like on high-performance materials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal matrix composite materials, and in particular to a high-modulus and high-strength aluminum matrix composite material formed by selective laser melting through coordinated regulation of nanoscale dual-ceramic particle hybrid reinforcement and subsequent heat treatment process, and a preparation method thereof. Background Art

[0002] At present, the research on aluminum-based composite materials formed by selective laser melting mainly focuses on the following directions: (1) Single-reinforcement phase aluminum-based composite material system: mainly using single ceramic particles such as SiC, Al2O3 or TiB2 as the reinforcement phase, and preparing them by ball milling combined with selective laser melting (SLM) process. For example, SiC reinforced aluminum-based composite materials. (2) Microalloying modification research: by adding microalloying elements such as Sc and Zr to the aluminum matrix, the nanoscale precipitation phase formed by them is used to achieve the strengthening effect. For example, the Al-Mg alloy system modified by Sc element is one of the key research directions. (3) Post-processing process optimization: for aluminum alloy materials formed by SLM, researchers often use the traditional T6 heat treatment system, that is, the combination process of solid solution + aging treatment to control the performance.

[0003] However, the existing technology has the following problems: (1) The problem of uniform distribution of reinforcement phase: When a single type of nanoparticles is added and the content exceeds a certain threshold, particle agglomeration is likely to occur during mechanical ball milling and SLM processing; this agglomeration will lead to uneven distribution of components within the molten pool, which in turn causes the material density to decrease, ultimately affecting the mechanical properties of the material. (2) Limitations of mechanical property improvement: Microalloying: Adding rare earth elements such as Sc can significantly improve material properties, but its high cost limits industrial application; Reinforcement phase: Although single reinforcement phase composite materials can improve matrix strength, the improvement is limited. (3) Heat treatment process adaptability problem: The traditional T6 treatment process (typical parameters are 500℃ solution treatment + aging treatment) easily leads to coarsening of the nano-reinforcement phase, which in turn causes a decrease in material strength. Therefore, it is urgent to design a new technical solution to comprehensively solve the problems existing in the background technology. Summary of the Invention

[0004] The purpose of the present invention is to provide a high modulus and high strength aluminum-based composite material and a preparation method thereof, which can effectively solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A high modulus and high strength aluminum-based composite material comprising aluminum alloy matrix powder and reinforcement phase particles; The aluminum alloy matrix powder comprises, in percentage by mass: Mg: 7-9 wt.%, Si: 0.4-2.5 wt.%, Mn: 0.3-0.8 wt.%, Sc: 0.5-0.7 wt.%, Zr: 0.2-0.5 wt.%, and the balance is Al and unavoidable impurities; The reinforcing phase particles include TiN and Si3N4 nanoparticles, wherein the addition amount of TiN is 1 wt.% of the mass of the aluminum-based composite powder mixture (aluminum alloy matrix powder and reinforcing phase particle mixture); the addition amount of Si3N4 is 1 wt.% of the mass of the aluminum-based composite powder mixture (aluminum alloy matrix powder and reinforcing phase particle mixture).

[0006] A further solution is that the particle size distribution of the aluminum alloy matrix powder is 15~53 μm; the average particle size of the TiN and Si3N4 nanoparticles in the reinforcement phase particles is 80 nm.

[0007] At the same time, the present invention also relates to a method for preparing a high-modulus and high-strength aluminum-based composite material, comprising the following steps: using a ball milling process to uniformly mix aluminum alloy matrix powder and reinforcement phase particles to obtain an aluminum-based composite powder mixture; then performing a molding experiment on the mixture through a selective laser melting process to obtain a sample material; and finally directly subjecting the sample material to aging heat treatment to obtain an aluminum-based composite material.

[0008] A further plan is that the parameters of the ball milling process are: ball-to-material ratio of 7:1; ball mill speed of 200 r / min; ball milling time of 2~3 h (30 min operation + 5 min pause); high-purity argon is filled in the ball milling process and the ball mill jar is sealed to ensure that the oxygen content is <100 ppm to avoid oxidation and ensure uniform dispersion of nanoparticles.

[0009] A further solution is that the steps of the selective laser melting process include: (1) Construct a three-dimensional model of the target sample, and then use slicing software to perform layer processing, setting the thickness of the single layer of powder to 40 μm; (2) A 20 mm thick AlSi10Mg substrate was selected, and the surface roughness Ra was controlled within 3.2~6.4 μm after sandblasting to ensure uniform spreading of the first layer of powder; (3) The laser additive manufacturing process was carried out under an argon protective atmosphere with the following process parameters: laser power: 350 W; scanning speed: 1000 mm / s; scanning spacing: 100 μm; powder layer thickness: 40 μm; scanning strategy: partitioned strip scanning, inter-layer rotation angle 67°.

[0010] The above process parameters have a significant impact on the forming quality of aluminum-based composites, and thus their mechanical properties. Changing the laser power, scanning speed, and scanning spacing will affect the relative density and defect situation of aluminum-based composites laser melting. This experiment is based on the research group's previous experimental research. The process parameters such as scanning spacing, powder layer thickness, scanning strategy, and interlayer rotation angle remain unchanged, while the laser power (250 W-450 W) and scanning speed (900-2500 mm / s) are changed. In the early process parameter optimization, it was found that with the increase of laser power, the forming quality of the composite material first increased and then decreased; with the increase of scanning speed, the quality of the composite material first increased and then decreased. Finally, the process parameters with the best forming quality (as shown above) were selected to obtain the best mechanical properties.

[0011] A further solution is that in step (3), the oxygen content must be ensured to be <100 ppm.

[0012] A further proposal proposed direct aging heat treatment process parameters: aging temperature: 325°C; holding time: 2 hours; cooling method: air cooling. The choice of aging temperature and time significantly affects the mechanical properties of aluminum-based composites. If the aging temperature is too low and the aging time is too long, while if the aging temperature is too high, the reinforcement phase tends to coarsen and become unevenly distributed, reducing the maximum strength of the composite. Through direct aging heat treatment experiments (300°C-375°C, holding time: 1 hour), the aging temperature was determined to be 325°C. The age-hardening curve at this temperature was developed, and the optimal aging time was determined to be 2 hours.

[0013] The high modulus and high strength aluminum-based composite material and its preparation method provided in the above technical solution prepare a new type of high modulus and high strength laser additive manufacturing aluminum-based composite material through the composite regulation of nano-scale TiN and Si3N4 mixed reinforcing particles and a specific heat treatment process. The high modulus and high strength aluminum-based composite material prepared by this method not only has excellent forming performance, but also has excellent mechanical properties, which can meet the needs of aerospace, automobile, shipbuilding and other fields for high-performance materials.

[0014] The prepared selective laser melting high modulus and high strength aluminum matrix composite material has the following advantages: (1) Uniform distribution of the reinforcement phase: The ball milling process ensures that the nanoparticles are evenly dispersed in the matrix, effectively avoiding agglomeration during the laser melting process; (2) High forming quality: The optimized laser parameters (laser power, scanning speed, and interlayer angle) effectively suppress pores and cracks, and the density of composite parts is ≥99.2%; (3) Excellent mechanical properties: After direct aging heat treatment, the composite material has a tensile strength of 586.4 MPa, a yield strength of 568.9 MPa, and a modulus of 78.7 GPa. Compared with the deposited matrix (tensile strength of 403.2 MPa, yield strength of 327.6 MPa, and modulus of 55.8 GPa), the tensile strength is increased by 45%, the yield strength is increased by 74%, and the modulus is increased by 41%. It is expected to meet the needs of aerospace and other fields for lightweight, high-modulus, and high-strength materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The morphology of the matrix aluminum alloy powder and the aluminum matrix composite material powder; Figure 2 Microstructure diagrams of different materials; Figure 3 is the hardness change curve of direct aging temperature and time; Figure 4 Comparison chart of tensile mechanical properties curves of different materials. DETAILED DESCRIPTION

[0016] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following examples. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection of the present invention.

[0017] This embodiment is a method for preparing a high modulus and high strength aluminum-based composite material, which specifically includes the following steps: (1) The average particle size of the Al-Mg-Si-Mn-Sc-Zr alloy powder is 26.74 μm. The specific ratio of the alloy elements is 8 wt.% of Mg, 1.4 wt.% of Si, 0.5 wt.% of Mn, 0.6 wt.% of Sc, 0.3 wt.% of Zr, and the rest is Al. 1 wt.% of nano-TiN and 1 wt.% of nano-Si3N4 particles are introduced into the alloy. The average size of the TiN and Si3N4 particles is 80 nm. The ball milling process is completed in a planetary ball mill at a speed of 200 rpm for 2 h. The ball milling process strategy is to run for 30 min and rest for 5 min. The total machine operation time is 2.25 h. The ball-to-material ratio is set to 7:1 to ensure that the TiN particles, Si3N4 particles and aluminum alloy matrix powder are evenly mixed to form an aluminum-based composite powder material synergistically reinforced by TiN and Si3N4. Figure 1 shown.

[0018] (2) A rectangular model with a size of 85 mm × 12 mm × 10 mm was constructed using 3D UG software on a computer. The model was converted into an STL file and imported into the slicing software for slicing. The data was then imported into the selective laser melting equipment for subsequent printing.

[0019] (3) Selective laser melting (SLM) was used to prepare aluminum alloy specimens without particles and aluminum-based composites with 1wt.% TiN+1wt.% Si3N4. A Concept laser M2cusing SLM machine was used to process a 20 mm thick AlSi10Mg substrate. The substrate was pre-treated with sandblasting to ensure the uniformity of the first layer of powder. Subsequently, a constant scanning strategy (rotating 67° between adjacent layers) was used to deposit the sample onto the substrate. During the manufacturing process, 99.999% pure argon was introduced into the chamber to keep the oxygen content below 100 ppm. The powder layer thickness was set to 40 μm, the laser power was 350 W, the scanning speed was 1000 mm / s, and the scanning pitch was 100 μm.

[0020] (4) The aluminum alloy matrix and TiN+Si3N4 synergistically reinforced aluminum matrix composite material prepared by the above-mentioned embodiment process have densities of 99.15% and 99.47% respectively, with excellent forming quality and no defects such as large pores and cracks. The material shows excellent forming performance. At the same time, Figure 2 The microstructure of the aluminum alloy matrix composite material was further revealed, as well as the distribution of nano-TiN particles and nano-Si3N4 particles and the morphology of the precipitated phase.

[0021] (5) Tensile tests were carried out on aluminum alloy matrix samples prepared by selective laser melting process and TiN+Si3N4 synergistically reinforced aluminum matrix composite samples. The results showed that the tensile strength of the matrix was 403.2 MPa, the yield strength was 327.6 MPa, the elongation was 7.7%, and the modulus was 55.8 GPa; the room temperature tensile strength of the TiN+Si3N4 synergistically reinforced aluminum matrix composite was 446.6 MPa, the yield strength was 412.3 MPa, the elongation was 3.8%, and the modulus was 75.1 GPa.

[0022] (6) The prepared TiN and Si3N4 synergistically reinforced aluminum matrix composite parts were heat treated. The aging temperature was determined to be 325 ℃ through direct aging heat treatment experiments (300 ℃-375 ℃, holding temperature for 1 h). The aging hardening curve at this temperature was developed to determine the optimal aging time to be 2 h, as shown in Figure 2. Figure 3As shown. Subsequently, the precision blast drying oven was heated to 325°C, and then the parts were placed in the drying oven, taken out after 2 hours of heat preservation, and cooled at room temperature. The tensile test results show that after heat treatment at 325°C for 2 hours, the room temperature tensile strength of the aluminum-based composite material is 586.4MPa, the yield strength is 568.9MPa, the elongation is 1.9%, and the modulus is 78.7 GPa. Compared with the deposited matrix (tensile strength of 403.2 MPa, yield strength of 327.6MPa, and modulus of 55.8 GPa), the tensile strength is increased by 45%, the yield strength is increased by 74%, and the modulus is increased by 41%, as shown in FIG. Figure 4 shown.

[0023] The above describes the implementation mode of the present invention in detail with reference to the embodiments. However, the present invention is not limited to the above implementation mode. After knowing the contents described in the present invention, ordinary technicians in this technical field can make several equivalent transformations and substitutions without departing from the principles of the present invention. These equivalent transformations and substitutions should also be regarded as falling within the scope of protection of the present invention.

Claims

1. A high modulus and high strength aluminum-based composite material, characterized in that: It includes aluminum alloy matrix powder and reinforcement phase particles; The aluminum alloy matrix powder comprises, in percentage by mass: Mg: 7-9 wt.%, Si: 0.4-2.5 wt.%, Mn: 0.3-0.8 wt.%, Sc: 0.5-0.7 wt.%, Zr: 0.2-0.5 wt.%, and the balance is Al and unavoidable impurities; The reinforcing phase particles include TiN and Si3N4 nanoparticles, wherein the addition amount of TiN is 1 wt.% of the total mass of the mixture; and the addition amount of Si3N4 is 1 wt.% of the total mass of the mixture.

2. The high modulus and high strength aluminum-based composite material according to claim 1, characterized in that: The particle size distribution of the aluminum alloy matrix powder is 15~53 μm; the average particle size of TiN and Si3N4 nanoparticles in the reinforcement phase particles is both 80 nm.

3. The method for preparing the high modulus and high strength aluminum-based composite material according to claim 1, wherein: The method comprises the following steps: uniformly mixing aluminum alloy matrix powder and reinforcement phase particles by a ball milling process to obtain an aluminum-based composite powder mixture; then subjecting the mixture to a forming experiment by a selective laser melting process to obtain a sample material; and finally directly subjecting the sample material to an aging heat treatment to obtain an aluminum-based composite material.

4. The method for preparing a high modulus and high strength aluminum-based composite material according to claim 3, characterized in that: The parameters of the ball milling process are as follows: ball-to-material ratio of 7:1; ball mill speed of 200 r / min; ball milling time of 2-3 h; high-purity argon gas was filled into the ball milling jar and the ball mill was sealed to ensure that the oxygen content was <100 ppm.

5. The method for preparing a high modulus and high strength aluminum-based composite material according to claim 3, wherein: The steps of the selective laser melting process include: (1) Construct a three-dimensional model of the target sample, and then use slicing software to perform layer processing, setting the thickness of the single layer of powder to 40 μm; (2) A 20 mm thick AlSi10Mg substrate was selected, and the surface roughness Ra was controlled within 3.2-6.4 μm after sandblasting to ensure uniform spreading of the first layer of powder; (3) Under argon protective atmosphere, the selective laser melting forming process was carried out with the following process parameters: laser power: 250~450W; scanning speed: 900~2500 mm / s; scanning spacing: 100 μm; powder layer thickness: 40 μm; scanning strategy: partitioned strip scanning, with an inter-layer rotation angle of 67°~90°.

6. The method for preparing a high modulus and high strength aluminum-based composite material according to claim 5, wherein: In step (3), the laser power is 350 W, the scanning speed is 1000 mm / s, and the interlayer rotation angle is 67°.

7. The method for preparing a high modulus and high strength aluminum-based composite material according to claim 5, wherein: In step (3), the oxygen content must be ensured to be <100 ppm.

8. The method for preparing a high modulus and high strength aluminum-based composite material according to claim 3, wherein: The process parameters of direct aging heat treatment are: aging temperature: 325 ℃; holding time: 2 h; cooling method: air cooling.

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