Characteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites.In the present work,we perform finite element simulations to elucidate fundamental mechanis...Characteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites.In the present work,we perform finite element simulations to elucidate fundamental mechanisms involved in the ultraprecision orthogonal cutting of aluminum-based silicon carbide composites(SiCp/AI),with an emphasis on the influence of particle distribution characteristic.The SiCp/AI composite with a particle volume fraction of 25 vol%and a mean particle size of 10|im consists of randomly distributed polygon-shaped SiC particles,the elastic deformation and brittle failure of which are described by the brittle cracking model.Simulation results reveal that in addition to metal matrix tearing,cuttinginduced particle deformation in terms of dislodging,debonding,and cracking plays an important role in the microscopic deformation and correlated machining force variation and machined surface integrity.It is found that the standard deviation of particle size to the mean value has a strong influence on the machinability of microscopic particle-tool edge interactions and macroscopically observed machining results.The present work provides a guideline for the rational synthesis of particulate-reinforced metal composites with high machinability.展开更多
Stir casting is one of the simplest ways of producing aluminum matrix composites.However,it suffers from poor incorporation and distribution of the reinforcement particles in the matrix.These problems become especiall...Stir casting is one of the simplest ways of producing aluminum matrix composites.However,it suffers from poor incorporation and distribution of the reinforcement particles in the matrix.These problems become especially significant as the reinforcement size decreases due to greater agglomeration tendency and reduced wettability of the particles with the melt.Development of new methods for addition of very fine particles to metallic melts which would result in more uniform distribution and effective incorporation of the reinforcement particles into the matrix alloy is therefore valuable.In this work,356-5%SiCp(volume fraction) composites,with average SiCp sizes of about 8 and 3 μm,were produced by injection of different forms of the reinforcement particles into fully liquid as well as semisolid slurries of 356 aluminum alloy and the effects of the injected reinforcement form and the casting method on distribution of the reinforcement particles as well as their porosity,hardness and impact strength were investigated.The results reveal that addition of SiC particles in the form of(Al-SiCp)cp composite powder and casting in semisolid state decreases the SiCp particle size,enhances the wettability between the molten matrix alloy and the reinforcements and improves the distribution of the reinforcement particles in the solidified matrix.It also increases the hardness and the impact energy of the composites and decreases their porosity.展开更多
The influences of SiC content on the microstructure, porosity, hardness and wear resistance of A356？SiCp composites processed via two different methods of compocasting and vibrating cooling slope （VCS） were compare...The influences of SiC content on the microstructure, porosity, hardness and wear resistance of A356？SiCp composites processed via two different methods of compocasting and vibrating cooling slope （VCS） were compared with each other. In the as-cast condition, the matrix of VCS and compocast processed composites exhibited globular and dendritric structures, respectively. While a more uniform distribution of SiC particulates in the matrix alloy as well as higher hardness values were obtained for the VCS processed samples, the composites produced via compocasting exhibited less porosity. The increased SiC content （up to 20% in volume fraction） resulted in a more uniform distribution of SiC particles within the matrix alloy and improved wear resistance for both the composite series. However, for the VCS processed composites, the increased SiC content, resulted in the decreased size and shape factor of globules as well as better tribological properties when compared with compocast composites. It was concluded that the improved properties of the VCS processed composites when compared with their compocast counterparts was a consequence of a more uniform distribution of SiC particulates in the matrix alloy as well as the globular microstructure generated during the VCS process.展开更多
基金Funding was provided by National Natural Science Foundation of China(Grant No.51761135106)Fundamental Research Funds for the Central Universities,Science Challenge Project(Grant Nos.TZ2018006-0201-02,TZ2018006-0205-02)State Key Lab of Digital Manufacturing Equipment and Technology(Grant Nos.DMETKF 2018007,DMETKF2019016).
文摘Characteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites.In the present work,we perform finite element simulations to elucidate fundamental mechanisms involved in the ultraprecision orthogonal cutting of aluminum-based silicon carbide composites(SiCp/AI),with an emphasis on the influence of particle distribution characteristic.The SiCp/AI composite with a particle volume fraction of 25 vol%and a mean particle size of 10|im consists of randomly distributed polygon-shaped SiC particles,the elastic deformation and brittle failure of which are described by the brittle cracking model.Simulation results reveal that in addition to metal matrix tearing,cuttinginduced particle deformation in terms of dislodging,debonding,and cracking plays an important role in the microscopic deformation and correlated machining force variation and machined surface integrity.It is found that the standard deviation of particle size to the mean value has a strong influence on the machinability of microscopic particle-tool edge interactions and macroscopically observed machining results.The present work provides a guideline for the rational synthesis of particulate-reinforced metal composites with high machinability.
文摘Stir casting is one of the simplest ways of producing aluminum matrix composites.However,it suffers from poor incorporation and distribution of the reinforcement particles in the matrix.These problems become especially significant as the reinforcement size decreases due to greater agglomeration tendency and reduced wettability of the particles with the melt.Development of new methods for addition of very fine particles to metallic melts which would result in more uniform distribution and effective incorporation of the reinforcement particles into the matrix alloy is therefore valuable.In this work,356-5%SiCp(volume fraction) composites,with average SiCp sizes of about 8 and 3 μm,were produced by injection of different forms of the reinforcement particles into fully liquid as well as semisolid slurries of 356 aluminum alloy and the effects of the injected reinforcement form and the casting method on distribution of the reinforcement particles as well as their porosity,hardness and impact strength were investigated.The results reveal that addition of SiC particles in the form of(Al-SiCp)cp composite powder and casting in semisolid state decreases the SiCp particle size,enhances the wettability between the molten matrix alloy and the reinforcements and improves the distribution of the reinforcement particles in the solidified matrix.It also increases the hardness and the impact energy of the composites and decreases their porosity.
文摘The influences of SiC content on the microstructure, porosity, hardness and wear resistance of A356？SiCp composites processed via two different methods of compocasting and vibrating cooling slope （VCS） were compared with each other. In the as-cast condition, the matrix of VCS and compocast processed composites exhibited globular and dendritric structures, respectively. While a more uniform distribution of SiC particulates in the matrix alloy as well as higher hardness values were obtained for the VCS processed samples, the composites produced via compocasting exhibited less porosity. The increased SiC content （up to 20% in volume fraction） resulted in a more uniform distribution of SiC particles within the matrix alloy and improved wear resistance for both the composite series. However, for the VCS processed composites, the increased SiC content, resulted in the decreased size and shape factor of globules as well as better tribological properties when compared with compocast composites. It was concluded that the improved properties of the VCS processed composites when compared with their compocast counterparts was a consequence of a more uniform distribution of SiC particulates in the matrix alloy as well as the globular microstructure generated during the VCS process.
基金Project (51175138) supported by the National Natural Science Foundation of ChinaProject (20100111110003) supported by Specialized Research Fund for the Doctoral Program of Higher Education, ChinaProject (10040606Y21) supported by the Science and Technological Fund of Anhui Province for Outstanding Youth, China
