CN111500905A - High-silicon aluminum alloy modified based on selective laser melting nano ceramic - Google Patents

High-silicon aluminum alloy modified based on selective laser melting nano ceramic Download PDF

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CN111500905A
CN111500905A CN202010363465.9A CN202010363465A CN111500905A CN 111500905 A CN111500905 A CN 111500905A CN 202010363465 A CN202010363465 A CN 202010363465A CN 111500905 A CN111500905 A CN 111500905A
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aluminum alloy
powder
laser melting
selective laser
silicon
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席丽霞
郭爽
顾冬冬
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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Abstract

The invention discloses a selective laser melting-based nano ceramic modified high-silicon aluminum alloy, which is characterized in that a high-energy ball milling process is adopted to prepare nano titanium diboride ceramic powder, then the high-silicon aluminum alloy powder and the nano titanium diboride ceramic powder are uniformly mixed under the protection of inert gas through a ball mill to obtain nano ceramic modified high-silicon aluminum alloy powder, and the nano ceramic modified high-silicon aluminum alloy powder is fused layer by selective laser melting forming equipment to form a target part to be established. In the process of solidifying the nano titanium diboride modified high-silicon aluminum alloy melt, the nano titanium diboride is used as a heterogeneous nucleation point to prevent the growth of silicon phase precipitated at the front edge of a solidification liquid phase, so that the star primary silicon phase is obviously reduced, the edge angle of the polygonal primary silicon phase is passivated, the edge is smooth, the fibrous eutectic silicon structure is also obviously refined, the size, the shape and the distribution state of the primary silicon phase and the eutectic silicon phase can be effectively adjusted, and the mechanical property of the high-silicon aluminum alloy is obviously improved.

Description

High-silicon aluminum alloy modified based on selective laser melting nano ceramic
Technical Field
The invention belongs to the field of high-silicon aluminum alloy materials, and particularly relates to a high-silicon aluminum alloy modified by nano ceramic based on selective laser melting.
Background
The high-silicon aluminum alloy has the advantages of low density, high strength, good corrosion resistance, low thermal expansion coefficient and the like, and has huge development potential and extremely wide application prospect in the fields of automobiles, aerospace, electronic packaging and the like. Unlike hypoeutectic and eutectic Al-Si alloys, the Si phase in the hypereutectic Si-Al alloy structure exists in the form of primary Si phase and eutectic Si phase. With the increase of the silicon content, the wear resistance and the heat resistance of the aluminum alloy are improved, but the size, the form and the distribution of primary crystal silicon and eutectic silicon phases in a microstructure of a formed piece also have obvious influence on the mechanical properties of the aluminum alloy, particularly, the coarse lath-shaped primary crystal silicon phase in a traditional casting structure seriously cracks the continuity of the structure, easily generates stress concentration at edges and sharp parts of the silicon phase, increases crack initiation particles, and finally reduces the strength and the elongation of the material. Based on the method, the nano ceramic phase is added into the aluminum matrix for structural modification, heterogeneous nucleation particles in the aluminum melt solidification process are increased, the shapes, sizes and distribution states of the primary silicon phase and the eutectic silicon phase are effectively adjusted, and the purpose of improving the mechanical properties of the material is finally achieved. In the common ceramic phase for modifying the aluminum alloy, the titanium diboride has the characteristics of higher elastic modulus (560GPa) and hardness (35GPa), excellent heat resistance and wear resistance, good wettability with an aluminum matrix and the like, so that the titanium diboride becomes an ideal structural modification material in the high-silicon aluminum alloy.
From the viewpoint of processing technology, in order to achieve the purposes of refining grains, homogenizing tissues and improving mechanical properties of materials, a rapid solidification method such as spray deposition and a powder metallurgy process is usually adopted when the hypereutectic high-silicon aluminum alloy is prepared, but the spray deposition method has complex equipment and process and high production cost, and parts prepared by the powder metallurgy process have high internal porosity and are difficult to form parts with complex structures. The selective laser melting technology is used as a novel rapid solidification technology, based on the local forming principle of layered manufacturing and cumulative superposition, and based on a three-dimensional part model designed by a computer, the selective melting, accumulation and forming are carried out on the metal powder material in a way of channel-by-channel layer-by-layer by using a high-energy laser heat source, so that the direct precise manufacturing of the metal component with the complex structure is realized. In the selective laser melting forming process, the action time of a laser heat source and a pre-laid powder layer is very short and is only about 0.5-20 ms, so that the molten material has a quite high cooling rate, favorable conditions are provided for grain refinement of the high-silicon aluminum alloy, and powder particles are completely melted under the action of a high-energy laser beam, so that adjacent scanning channels or interlaminar metallurgical bonding is good, the forming quality of the high-silicon aluminum alloy part is improved, and the mechanical property of the material is improved. The selective laser melting technology breaks through the constraint of the traditional manufacturing process, accords with the design concept of near-net-shape forming, effectively shortens the development and manufacturing period of new products, improves the production efficiency, and can form parts with complex geometric structures, so that the selective laser melting technology has great development potential for preparing high-silicon aluminum alloy materials.
Disclosure of Invention
Aiming at the problems of the existing high-silicon aluminum alloy material preparation technology and simultaneously meeting the improvement requirements, the invention provides a nano ceramic modified high-silicon aluminum alloy based on a selective laser melting technology so as to obviously improve the mechanical properties of the high-silicon aluminum alloy.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a high-silicon aluminum alloy modified by nano ceramic based on selective laser melting comprises the following steps:
(1) the nanometer is prepared by adopting a Pulverisette 6 type single-pot planetary high-energy ball milling processRice TiB2A ceramic powder;
(2) mixing Al-20Si alloy powder with the nano TiB prepared in the step (1)2The ceramic powder is evenly mixed by a QM series planetary ball mill under the protection of inert gas to obtain the nano TiB2Al-20Si composite powder;
(3) establishing a three-dimensional entity geometric model of a target part by using Soildworks software in a computer, then carrying out layered slicing on the model by using Magics software, planning a laser scanning path, dispersing a three-dimensional entity into a series of two-dimensional data, storing the file and importing the file into selective laser melting forming equipment;
(4) the selective laser melting forming equipment is used for melting the nano TiB in the step (2) according to the file saved in the step (3)2Melting the/Al-20 Si composite powder layer by layer, and forming into the target part to be established.
Preferably, in step (1), the starting material used is polygonal micron TiB2The powder has a particle size distribution range of 1-5 μm and a purity of more than 99.9%.
Preferably, in the step (1), the high-energy ball milling rotation speed is 250-300 rpm, and the ball milling time is 20-25 h.
Preferably, in the step (1), the nano TiB prepared by high-energy ball milling2The ceramic powder has a particle size of 40 to 200 nm.
Preferably, in the step (2), the particle size distribution of the Al-20Si alloy powder is 12-31 μm, wherein the content of silicon is 19.2-20 wt.%, the content of iron is 0.05-0.15%, and the balance is aluminum.
Preferably, in step (2), the TiB2Nano TiB in/Al-20 Si composite powder2The content of the particles is 1-10 wt.%, most preferably 2 wt.%, and if the nano TiB is used, the content is 1-10 wt.%2The particle content is too low, and the modification effect is poor; if nano TiB2The particle content is too high, the laser forming quality is reduced, and the performance of the composite material is influenced.
Specifically, the ball mill in the step (2) adopts a QM series planetary ball mill to perform the ball milling and powder mixing operation, the process adopts a ceramic pot, and the ball milling media are ceramic grinding balls with the diameters of 6mm and 8 mm. The ball milling process parameters are set as follows: the ball material ratio is 2: 1; meanwhile, in order to prevent the temperature in the ball milling tank from being overhigh, the operation mode of the equipment is selected in a spaced mode during ball milling, namely the air cooling is suspended for 5min after the equipment operates for 15 min. The ball milling process requires that it be conducted under inert gas shielding to prevent oxidation or contamination of the aluminum alloy powder.
Preferably, in the step (2), the ball milling speed is 150-250 rpm, and the ball milling time is 3-5 h.
The method comprises the following steps of (a) uniformly laying powder to be processed on a forming substrate by a powder laying device, scanning a slicing area line by a laser beam according to a pre-designed scanning path to enable the powder layer to be rapidly melted and solidified, so as to obtain a first two-dimensional plane of the part, (b) enabling the forming substrate to descend by a powder layer thickness by the computer control system, conversely, enabling a piston of a powder supply cylinder to ascend by a powder layer thickness, laying a layer of powder to be processed by the powder laying device, completing scanning of a second powder layer according to slicing information by the laser beam to obtain a second two-dimensional plane of the part, 2200) repeating the steps above, processing the powder to be processed to a powder layer thickness, preferably, the step of scanning the powder to be processed to a step of 50 mu M, and optimizing the laser power to be used for processing the island-shaped parts (the step is a laser melting process) to be 50 mu M, wherein the laser power is equal to 50 mu M.
According to the characteristics of the structure and the performance of the high-silicon aluminum alloy material, the high-silicon aluminum alloy structure modifier can be reasonably selected and properly added, and the preparation method combined with the leading-edge laser additive manufacturing technology is adopted, so that the appearance, the size and the distribution state of a silicon phase can be effectively adjusted, and the high-silicon aluminum alloy material with excellent comprehensive performance can be successfully prepared.
Has the advantages that:
(1) the invention takes micron-sized titanium diboride powder as raw material and utilizes a high-energy ball milling process to prepare the nano TiB2Powder and the prepared nano TiB2Mixing with Al-20Si powder, ball milling in a QM planetary ball mill, and optimizing to obtain nanometer TiB2TiB with uniform distribution and good flow property and suitable for selective laser melting forming2The process is simple to operate and saves cost.
(2) Compared with Al-20Si alloy powder, the nano TiB2The laser absorption rate of the Al-20Si powder is obviously increased, and the laser energy input of the powder bed is increased in the selective laser melting forming process, so that the powder layer can be fully melted, and the forming quality of parts is improved.
(3) The method for preparing the high-silicon aluminum alloy material by using the selective laser melting technology not only shortens the production period and improves the production efficiency of products, but also can form parts with complex geometric shapes almost without subsequent machining treatment. The cooling speed of the molten pool is extremely high and can reach 10 when the selective laser melting forming is carried out3～108K/s, the super-cooling degree of the high-silicon aluminum alloy melt is increased, the generation of thick dendrites in the traditional processing technology is avoided, and the mechanical property of the part is improved.
(4) In TiB2In the process of solidifying Al-20Si melt, the nano TiB2Heterogeneous nucleation points precipitated by the silicon phase are increased, the growth of the precipitated silicon phase at the front edge of the solidification liquid phase is hindered, the star-shaped primary silicon phase is obviously reduced, the edges of the polygonal primary silicon phase are passivated, the edges are smooth, and the fibrous eutectic silicon structure is also obviously refined. The invention passes through the nano TiB2The refining and modifying effects on the primary silicon phase and the eutectic silicon phase in the high-silicon aluminum alloy structure can effectively adjust the shapes and distribution states of the primary silicon phase and the eutectic silicon phase, and obviously improve the mechanical properties of Al-20 Si.
(5) The optimal laser power of the high-silicon aluminum alloy formed by selective laser melting is obtained through early-stage process optimization, and the laser energy density is adjusted by changing the laser scanning speed. Along with the change of laser energy input of the powder bed, the laser and the powder bedThe thermodynamics and dynamics characteristics of the molten pool formed by the action are changed, the laser energy input is adjusted by reasonably selecting laser process parameters, the metallurgical defects such as spheroidization effect, pores and cracks are reduced, and TiB with compact structure and good comprehensive performance is obtained2The Al-20Si composite material.
Drawings
Other advantages of the invention will become apparent from the following more detailed description of the invention, when taken in conjunction with the accompanying drawings and detailed description.
FIG. 1 shows the preparation of nano TiB by high energy ball milling process in example 12TEM image of (a).
FIG. 2 shows the TiB obtained in example 32SEM image of/Al-20 Si composite powder.
FIG. 3 shows the selective laser melting of nano-TiB prepared in example 32A photograph of a sample of the/Al-20 Si composite material.
FIG. 4 shows the selected area laser melting forming of nano-TiB in example 32SEM image of/Al-20 Si composite sample.
FIG. 5 is an SEM image of a selected area laser fusion formed Al-20Si alloy specimen of comparative example 1.
FIG. 6 shows the selected area laser melting forming of micro TiB in comparative example 32SEM images of/AlSi 10Mg composite samples.
Detailed Description
The invention will be better understood from the following examples.
In the following examples, TiB was used2The powder raw material is polygonal micron TiB2The powder has a particle size distribution range of 1-5 μm and a purity of more than 99.9%. The grain size of the Al-20Si alloy powder is 12-31 mu m, wherein the content of silicon is 19.2-20 wt.%, the content of iron is 0.11%, and the balance is aluminum.
Example 1
(1) Preparation of nano TiB by high-energy ball milling process2The high-energy ball milling equipment is a Pulverisette 6 type single-pot planetary high-energy ball mill, the ball milling medium in the stainless steel ball mill pot is stainless steel grinding balls with the diameter of 6mm and 20mm, and the ball-material ratio is 10: 1. When in useWhen the equipment works, the stainless steel ball milling tank rotates around the self-axis at a fixed speed, and simultaneously revolves around a fixed axis parallel to the self-axis, the ball milling speed is set to 250rpm, the ball milling time is 25h, and the grinding balls and the ceramic powder collide and impact with each other in the high-energy ball milling process to break ceramic phase particles, so that the nano TiB is obtained2A ceramic powder. The nanometer TiB prepared by the high-energy ball milling process2Powder TEM images are shown in figure 1.
(2) Nano TiB prepared in the step (1)2Adding ceramic powder into Al-20Si alloy powder according to the proportion of 1 wt.%, and performing ball milling and powder mixing to prepare TiB2The Al-20Si composite powder. The ball milling and powder mixing operation is carried out in a QM series planetary ball mill, a ceramic pot is adopted in the process, and the ball milling media are ceramic grinding balls with the diameters of 6mm and 8 mm. The ball milling process parameters are set as follows: the ball-material ratio is 2:1, the ball milling speed is 150rpm, and the ball milling time is 5 h. Meanwhile, in order to prevent the temperature in the ball milling tank from being overhigh, the operation mode of the equipment is selected in a spaced mode during ball milling, namely the air cooling is suspended for 5min after the equipment operates for 15 min. The ball milling process requires that it be conducted under argon protection to prevent oxidation or contamination of the aluminum alloy powder.
(3) Target part modeling and slicing process
The method comprises the steps of establishing a three-dimensional solid geometric model of a target part in a computer by using Soildworks software, then carrying out layered slicing and scanning path planning on the three-dimensional solid model by using Magics software, dispersing the three-dimensional solid into a series of two-dimensional data, storing the file and importing the file into selective laser melting forming equipment. Wherein the laser process parameters are set as follows: the laser power is 450W, the laser scanning speed is 1800mm/s, the scanning interval is 50 μm, the powder spreading thickness is 50 μm, a subarea island scanning strategy is adopted, and the rotation angle of the laser scanning direction of the adjacent layer is 37 degrees.
(4) Selective laser fusion forming process
The nano ceramic modified high-silicon aluminum alloy powder prepared in the step (2) is used for selective laser melting forming, S L M-150 type selective laser melting equipment is adopted, and the system mainly comprises a Y L R-500 type optical fiber laser, a laser forming chamber, an automatic powder laying system, a protective atmosphere device and a computer control systemA circuit manufacturing system and a cooling circulation system. Before forming, the aluminum substrate subjected to sand blasting treatment is fixed on a workbench of selective laser melting forming equipment and leveled, then a forming cavity is sealed and vacuumized by a sealing device, and argon protective atmosphere (the purity of argon is 99.999 percent, the outlet pressure is 30mbar) is introduced to ensure that O in a forming chamber2The content is less than 10 ppm. A typical selective laser fusion forming process is as follows: (a) the powder spreading device uniformly spreads the powder to be processed on the forming substrate, and the laser beam scans the slice area line by line according to a pre-designed scanning path to rapidly melt and solidify the powder layer, so that a first two-dimensional plane of the part is obtained; (b) the computer control system enables the forming substrate to descend by one powder layer thickness, conversely, enables the powder supply cylinder piston to ascend by one powder layer thickness, the powder laying device re-lays a layer of powder to be processed, and the laser beam completes scanning of a second powder layer according to the slicing information to obtain a second two-dimensional plane of the part; (c) and repeating the steps, and forming the powder to be processed layer by layer until the part is processed.
And after cooling, taking the formed substrate out of the equipment, and separating the part from the substrate by using a linear cutting process to obtain the nano titanium diboride modified high-silicon aluminum alloy sample. And grinding, polishing and corroding the nano titanium diboride modified high-silicon aluminum alloy block sample according to a standard metallographic sample preparation method.
TiB to be obtained2The tensile strength of the/Al-20 Si standard tensile sample can reach 409MPa after the room temperature tensile test.
Example 2
(1) Preparation of nano TiB by high-energy ball milling process2The high-energy ball milling equipment is a Pulverisette 6 type single-pot planetary high-energy ball mill, the ball milling medium in the stainless steel ball mill pot is stainless steel grinding balls with the diameter of 6mm and 20mm, and the ball-material ratio is 10: 1. When the equipment works, the stainless steel ball milling tank rotates around the self-axis at a fixed speed, and simultaneously revolves around a fixed axis parallel to the self-axis, the ball milling speed is set to 280rpm, the ball milling time is 23h, and the grinding balls and the ceramic powder collide and impact with each other in the high-energy ball milling process to break ceramic phase particles, so that the nano TiB is obtained2A ceramic powder.
(2) Nano TiB prepared in the step (1)2Adding ceramic powder into Al-20Si alloy powder according to the proportion of 10 wt.%, and performing ball milling and powder mixing to prepare TiB2The Al-20Si composite powder. The ball milling and powder mixing operation is carried out in a QM series planetary ball mill, a ceramic pot is adopted in the process, and the ball milling media are ceramic grinding balls with the diameters of 6mm and 8 mm. The ball milling process parameters are set as follows: the ball-material ratio is 2:1, the ball milling speed is 200rpm, and the ball milling time is 4 h. Meanwhile, in order to prevent the temperature in the ball milling tank from being overhigh, the operation mode of the equipment is selected in a spaced mode during ball milling, namely the air cooling is suspended for 5min after the equipment operates for 15 min. The ball milling process requires that it be conducted under argon protection to prevent oxidation or contamination of the aluminum alloy powder.
(3) Target part modeling and slicing process
The method comprises the steps of establishing a three-dimensional solid geometric model of a target part in a computer by using Soildworks software, then carrying out layered slicing and scanning path planning on the three-dimensional solid model by using Magics software, dispersing the three-dimensional solid into a series of two-dimensional data, storing the file and importing the file into selective laser melting forming equipment. Wherein the laser process parameters are set as follows: the laser power is 450W, the laser scanning speed is 2000mm/s, the scanning interval is 50 μm, the powder spreading thickness is 50 μm, a subarea island scanning strategy is adopted, and the rotation angle of the laser scanning direction of the adjacent layer is 37 degrees.
(4) Selective laser fusion forming process
Adopting S L M-150 type selective laser melting equipment, wherein the system mainly comprises a Y L R-500 type optical fiber laser, a laser forming chamber, an automatic powder laying system, a protective atmosphere device, a computer control circuit system and a cooling circulation system, fixing the aluminum substrate subjected to sand blasting treatment on a workbench of the selective laser melting forming equipment and leveling the aluminum substrate before forming, sealing and vacuumizing a forming cavity through a sealing device, and introducing argon protective atmosphere (the purity of argon is 99.999 percent, the outlet pressure is 30mbar) to ensure that O in the forming chamber is ensured2The content is less than 10 ppm. A typical selective laser fusion forming process is as follows: (a)the powder spreading device uniformly spreads the powder to be processed on the forming substrate, and the laser beam scans the slice area line by line according to a pre-designed scanning path to rapidly melt and solidify the powder layer, so that a first two-dimensional plane of the part is obtained; (b) the computer control system enables the forming substrate to descend by one powder layer thickness, conversely, enables the powder supply cylinder piston to ascend by one powder layer thickness, the powder laying device re-lays a layer of powder to be processed, and the laser beam completes scanning of a second powder layer according to the slicing information to obtain a second two-dimensional plane of the part; (c) and repeating the steps, and forming the powder to be processed layer by layer until the part is processed.
And after cooling, taking the formed substrate out of the equipment, and separating the part from the substrate by using a linear cutting process to obtain the nano titanium diboride modified high-silicon aluminum alloy sample. And grinding, polishing and corroding the nano titanium diboride modified high-silicon aluminum alloy block sample according to a standard metallographic sample preparation method.
TiB to be obtained2The tensile strength of the/Al-20 Si standard tensile sample can reach 472MPa by a room-temperature tensile test.
Example 3
(1) Preparation of nano TiB by high-energy ball milling process2The high-energy ball milling equipment is a Pulverisette 6 type single-pot planetary high-energy ball mill, the ball milling medium in the stainless steel ball mill pot is stainless steel grinding balls with the diameter of 6mm and 20mm, and the ball-material ratio is 10: 1. When the equipment works, the stainless steel ball milling tank rotates around the self-axis at a fixed speed, and simultaneously revolves around a fixed axis parallel to the self-axis, the ball milling speed is set to 300rpm, the ball milling time is 20 hours, and the grinding balls and the ceramic powder collide and impact with each other in the high-energy ball milling process to break ceramic phase particles, so that the nano TiB is obtained2A ceramic powder.
(2) Nano TiB prepared in the step (1)2Adding ceramic powder into Al-20Si alloy powder according to the proportion of 2 wt.%, and performing ball milling and powder mixing to prepare TiB2The Al-20Si composite powder. The ball milling and powder mixing operation is carried out in a QM series planetary ball mill, a ceramic pot is adopted in the process, and the ball milling media are ceramic grinding balls with the diameters of 6mm and 8 mm. Ball milling process parameters are set to: the ball-material ratio is 2:1, the ball milling speed is 250rpm, and the ball milling time is 3 h. Meanwhile, in order to prevent the temperature in the ball milling tank from being overhigh, the operation mode of the equipment is selected in a spaced mode during ball milling, namely the air cooling is suspended for 5min after the equipment operates for 15 min. The ball milling process requires that it be conducted under argon protection to prevent oxidation or contamination of the aluminum alloy powder. The nanometer TiB prepared by the ball milling mixed powder2SEM images of the/Al-20 Si powder are shown in FIG. 2.
(3) Target part modeling and slicing process
The method comprises the steps of establishing a three-dimensional solid geometric model of a target part in a computer by using Soildworks software, then carrying out layered slicing and scanning path planning on the three-dimensional solid model by using Magics software, dispersing the three-dimensional solid into a series of two-dimensional data, storing the file and importing the file into selective laser melting forming equipment. Wherein the laser process parameters are set as follows: the laser power is 450W, the laser scanning speed is 2200mm/s, the scanning interval is 50 μm, the powder spreading thickness is 50 μm, a subarea island-shaped scanning strategy is adopted, and the rotation angle of the laser scanning direction of the adjacent layer is 37 degrees.
(4) Selective laser fusion forming process
Adopting S L M-150 type selective laser melting equipment, wherein the system mainly comprises a Y L R-500 type optical fiber laser, a laser forming chamber, an automatic powder laying system, a protective atmosphere device, a computer control circuit system and a cooling circulation system, fixing the aluminum substrate subjected to sand blasting treatment on a workbench of the selective laser melting forming equipment and leveling the aluminum substrate before forming, sealing and vacuumizing a forming cavity through a sealing device, and introducing argon protective atmosphere (the purity of argon is 99.999 percent, the outlet pressure is 30mbar) to ensure that O in the forming chamber is ensured2The content is less than 10 ppm. A typical selective laser fusion forming process is as follows: (a) the powder spreading device uniformly spreads the powder to be processed on the forming substrate, and the laser beam scans the slice area line by line according to a pre-designed scanning path to rapidly melt and solidify the powder layer, so that a first two-dimensional plane of the part is obtained; (b) the computer control system lowers the formed substrate by one layer thickness and converselyEnabling the piston of the powder supply cylinder to rise by one powder layer thickness, laying a layer of powder to be processed again by the powder laying device, and finishing scanning of a second powder layer by the laser beam according to the slicing information to obtain a second two-dimensional plane of the part; (c) and repeating the steps, and forming the powder to be processed layer by layer until the part is processed, wherein the step is shown in figure 3. The nano TiB prepared by the selective laser melting process2The microstructure of the/Al-20 Si composite sample is shown in FIG. 4.
And after cooling, taking the formed substrate out of the equipment, and separating the part from the substrate by using a linear cutting process to obtain the nano titanium diboride modified high-silicon aluminum alloy sample. And grinding, polishing and corroding the nano titanium diboride modified high-silicon aluminum alloy block sample according to a standard metallographic sample preparation method. In this example, the nano-TiB2The microstructure morphology of the/Al-20 Si composite sample is shown in FIG. 4.
TiB to be obtained2The tensile strength of the/Al-20 Si standard tensile sample can reach 494MPa when the tensile sample is subjected to a room temperature tensile test.
Comparative example 1
The specific steps of the preparation method are basically the same as those of the embodiment 3, and the difference is that: in the steps (1) and (2) of the comparative example, the nano TiB is not used2Preparing nano TiB by using ball milling process as raw material2The Al-20Si composite powder is prepared by selecting near-spherical Al-20Si alloy powder prepared by gas atomization as a raw material, and performing selective laser melting forming, wherein the microstructure of the near-spherical Al-20Si alloy powder is shown in figure 5. Comparing FIG. 4 with FIG. 5, it can be seen that the nano-TiB2Compared with the Al-20Si composite material, the quantity of star-shaped and polygonal primary silicon phases in the Al-20Si alloy structure is obviously increased and is dispersed unevenly to present an aggregation state, the size of fibrous eutectic silicon is obviously increased, stress concentration is easy to occur at a brittle silicon phase aggregation area or the polygonal edge of the primary silicon phase with larger size, cracks are generated and expanded too early, and thus the mechanical property of the material is reduced.
And (4) performing a room-temperature tensile test on the Al-20Si alloy standard tensile sample prepared in the step (3), wherein the tensile strength of the Al-20Si alloy standard tensile sample can reach 357 MPa.
Comparative example 2
The specific steps of the preparation method are basically the same as those of the embodiment 3, and the difference is that: in step (2) of this comparative example, nano TiB2TiB in/Al-20 Si composite powder2The nanoparticle content was 25 wt.%. In this comparative example, since the nano TiB2The addition of ceramic in too high an amount causes agglomeration of nanoparticles and a significant increase in the viscosity of the aluminum melt, and the gaps between powder particles are not sufficiently filled with melt during subsequent solidification to form void defects, thus resulting in a severe deterioration in the quality and properties of the sample.
Comparative example 3
The specific steps of the preparation method are basically the same as those of the embodiment 3, and the difference is that: in steps (1) and (2) of this comparative example, the TiB is measured in microns2And AlSi10Mg alloy powder as raw materials, and preparing 2 wt.% TiB by adopting a ball milling process2The microstructure of the/AlSi 10Mg composite powder was formed by selective laser melting, as shown in fig. 6. Comparing FIGS. 4 and 6, it can be seen that the nano-TiB2Compared with Al-20Si composite material, micron TiB2The eutectic silicon structure in the AlSi10Mg composite material is obviously coarsened, which is mainly caused by the weak refinement degree of the microstructure of the micron ceramic relative to the aluminum matrix composite material relative to the nano ceramic phase; while the larger size ceramic phase increases the tendency of the material to stress concentrate and crack within it. The aluminum alloy used in the embodiment has low silicon content (12.6 wt.% lower than the eutectic point of the aluminum-silicon alloy), and no uniformly distributed tiny massive primary silicon phase is precipitated in the solidification process of the aluminum alloy melt, so that the strength of the composite material is reduced.
TiB by room temperature tensile test2The tensile strength of the/AlSi 10Mg composite material was 444 MPa.
From examples 1 to 3 and comparative examples 1 to 3, it can be seen that the selective laser melting formation of the nano TiB2The tensile strength of the/Al-20 Si composite material sample is obviously increased, and the mechanical property is obviously improved, which is mainly attributed to the nanometer TiB2For high silicon aluminum alloy groupRefining and modifying the primary silicon phase and eutectic silicon phase in the texture. Compared with Al-20Si alloy, the nano TiB2The star-shaped primary silicon phase in the Al-20Si composite material is obviously reduced, the edges of the polygonal primary silicon phase are passivated, the edges are smooth, and the fibrous eutectic silicon structure is obviously refined. Nano TiB2Uniformly distributed on the aluminum matrix, has dispersion strengthening effect on the high-silicon aluminum alloy matrix, and TiB2The wettability of the ceramic and the aluminum alloy is better, so that the nano TiB2The interface between the ceramic phase and the aluminum matrix is tightly combined, and the mechanical property of the material is further improved.
The invention provides a thought and a method for modifying high-silicon aluminum alloy based on selective laser melting nano ceramic, and a method and a way for realizing the technical scheme are many, the above description is only a preferred embodiment of the invention, and it should be noted that for a person skilled in the art, on the premise of not departing from the principle of the invention, a plurality of improvements and decorations can be made, and the improvements and decorations should be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims (8)

1. A high-silicon aluminum alloy modified by nano ceramic based on selective laser melting is characterized by being prepared by the following steps:
(1) preparation of nano TiB by using Pulverisette 6 type single-pot planetary high-energy ball mill2A ceramic powder;
(2) mixing Al-20Si alloy powder with the nano TiB prepared in the step (1)2The ceramic powder is evenly mixed by a QM series planetary ball mill under the protection of inert gas to obtain the nano TiB2Al-20Si composite powder;
(3) establishing a three-dimensional entity geometric model of a target part by using Soildworks software in a computer, then carrying out layered slicing on the model by using Magics software, planning a laser scanning path, dispersing a three-dimensional entity into a series of two-dimensional data, storing the file and importing the file into selective laser melting forming equipment;
(4) the selective laser melting forming equipment is protected according to the step (3)Storing the file, namely the nano TiB in the step (2)2And fusing the/Al-20 Si composite powder layer by layer, and finally forming the target part to be built.
2. The selective laser melting nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (1), the used raw material is polygonal micro TiB2The powder has a particle size distribution range of 1-5 μm and a purity of more than 99.9%.
3. The selective laser melting based nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (1), the high-energy ball milling rotation speed is 250-300 rpm, and the ball milling time is 20-25 h.
4. The selective laser melting nanoceramic modified high-silicon aluminum alloy according to claim 3, wherein in the step (1), the prepared nano TiB is prepared by high-energy ball milling2The ceramic powder has a particle size of 40 to 200 nm.
5. The selected-region-based laser melting nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (2), the grain size distribution range of the Al-20Si alloy powder is 12-31 μm, the silicon content is 19.2-20 wt.%, the iron content is 0.05-0.15%, and the balance is aluminum.
6. The selective laser melting nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (2), the nano TiB2TiB in/Al-20 Si composite powder2The content of the nano particles is 1-10 wt.%.
7. The selective laser melting based nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (2), the ball milling rotation speed is 150-250 rpm, and the ball milling time is 3-5 h.
8. The selective laser melting based nanoceramic modified high-silicon aluminum alloy according to claim 1, wherein in the step (4), the scanning speed of the laser used for selective laser melting is 1800-2200 mm/s.
CN202010363465.9A 2020-04-30 2020-04-30 High-silicon aluminum alloy modified based on selective laser melting nano ceramic Pending CN111500905A (en)

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CN112207278A (en) * 2020-08-20 2021-01-12 南京航空航天大学 Selective laser melting additive manufacturing and discharge combined machining method for aluminum alloy gear
CN112974842A (en) * 2021-02-05 2021-06-18 南京航空航天大学 Nano multiphase reinforced aluminum matrix composite material and preparation method thereof
CN113881873A (en) * 2021-09-16 2022-01-04 南京航空航天大学 High-density trans-scale solid solution ceramic reinforced aluminum matrix composite and preparation method thereof
CN114054745A (en) * 2021-11-23 2022-02-18 山东大学 Aluminum alloy powder, preparation method and application thereof, and aluminum alloy member

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CN112207278A (en) * 2020-08-20 2021-01-12 南京航空航天大学 Selective laser melting additive manufacturing and discharge combined machining method for aluminum alloy gear
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