Study On Preparation And Properties Of SiC Particles Reinforced6061Aluminum Matrix Composites

SiC particle reinforced aluminum matrix composites is a new material, which shows many excellent characteristics against the traditional metal such as low density, its controlled expansion coefficient, well thermal conductivity and high specific strength and so on. The SiCP/Al composites have been used in many applications such as aerospace, aircraft and also have been research focus at present. The SiCp/6061Al composites were fabricated by powder metallurgy route and the preparation, structure and properties were researched in this paper.6061Al powers were used as matrix material, SiC particles as reinforcement,30%SiCp/6061Al composites were manufactured by vacuum hot pressing method. The density and tensile strength were tested, and the microstructures of the materials were analyzed by SEM. The temperature and pressure of hot pressing technology were analyzed, reaching the applicable technology that the temperature is580℃and the pressure is70MPa. The SiCp/6061Al composites were produced using the technology, with the SiC particle volume fraction being25%,30%,35%respectively and the effect of SiC particles volume fraction on the microstructure and properties of the composites were analyzed. The results showed that with the increase of the SiC particles volume fraction in the composites, the densification and coefficients of thermal expansion decrease and the tensile strength increases at first and decreases then. The clustering degree of the SiC particles increased in the matrix.There were used to reduce the clustering degree of SiC particles which contain using wet-ball energy ball milling method to pretreat the mixed powders, changing the diameter of matrix powders and SiC particles diameter. The35%SiCp/6061Al composites were produced by the three technologies and the properties were compared. The effect of different methods on the composites was studied respectively. The results showed that the clustering degree of the SiC particles was decreased and the mechanical property was increased by the technologies. However the best technology was changing diameter of matrix and reinforcement and it could more effectively decrease the clustering degree of SiC particles. Reaching out the appropriate producing technology of fabricating the composites by hot pressing method:10μm6061powders as matrix and7.5μm SiC particles as reinforcement were sintered at580℃and70MPa pressure circumstances.The35%SiCp/6061Al composites fabricated by vacuum hot pressing method were squeezed at high temperature. The density of the specimens was measured and the microstructure and properties were analyzed before and after hot extrusion. The composites were heated treatment and the organization and properties were studied. The results showed that SiC particles could distribute more uniformly after hot extrusion and the mechanical properties great increased. The appropriate solution temperature is530℃, solution time is90minutes, and the aging temperature is180℃, aging time is10hours. The mechanical properties were best using the heat treatment technology and the tensile strength could reach to334MPa.The fracture organization of the composites was observed and the fracture and strengthen mechanism were evaluated. The breakage of the composites was mainly due to tearing of the matrix and the failure of the SiC particles from the matrix. The dimple got deeper after hot extrusion. A good semi-coherent bonding existed between SiC and Al phase. There was no interfacial reactions generated in the interface of SiC and Al and there was semi-coherent boundary on (022) crystal face. The strengthen mechanism were refined crystalline strengthening and dislocations strengthening.