Effect Of Aluminum Alloy Infiltration On Properties Of SiC

SiC has many excellent properties,such as high strength,low density,high hardness,good wear resistance and chemical stability.However,the intrinsic brittleness severely restricts its application in practical engineering.Therefore,strengthening and toughening of SiC is always a hotspot in materials science research.In order to improve the toughness of SiC,an effective method is to introduce ductile metal to toughen SiC.In this paper,Al/SiC composites were fabricated by pressureless melt infiltration method.The effects of preparation process and alloy composition on the microstructure and properties of the composites were researched.The experimental results show that the elevated temperature can not only reduce the viscosity of the alloy liquid,but also promote the destruction of the Al₂O₃ film and improve the wettability of the Al/SiC system.When the holding time is not enough,the cracks in the composites are produced and the mechanical properties of the composites are reduced due to the slow infiltration rate.With the increase of infiltration temperature and time,the interfacial reaction is easy to generate more brittle Al₄C₃ which reduces the mechanical properties and causes the pulverization of the composites.Si can accelerate the spreading of aluminum alloy on the SiC and improve the wettability of the system.When 10%Si is added into the alloy,Al₄C₃ is effectively inhibited on the Al/SiC interface.The bending strength and fracture toughness of the composites are optimal,which are 348 MPa and 3.1 MPa·m^1/2,respectively.When the Si content is 15%,primary silicon with larger size is produced in the composites.Under the same preparation conditions,Al-Si/SiC composites have higher corrosion resistance than that of Al/SiC composites.Ti produces Ti₃Si?Al?C₂ at the interface which improves the wettability of the Al-Si/SiC system.With the increase of Ti contents,the thickness of the Ti₃Si?Al?C₂ reaction layer increases,the hardness of the composites decreases,and the bending strength and fracture toughness increase.When 15%Ti was added into the alloy,the bending strength and fracture toughness were 467 MPa and 4.88 MPa·m^1/2,respectively.Ti decreases the corrosion resistance of Al alloy/SiC composites.