The Al/Si/SiC composites with medium volume fraction for electronic packaging were fabricated by gas pressure infiltration.On the premise of keeping the machinability of the composites,the silicon carbide particles,which have the similar size with silicon particles（average 13 μm）,were added to replace silicon particles of same volume fraction,and microstructure and properties of the composites were investigated.The results show that reinforcing particles are distributed uniformly and no apparent pores are observed in the composites.It is also observed that higher thermal conductivity（TC） and flexural strength will be obtained with the addition of SiC particles.Meanwhile,coefficient of thermal expansion（CTE） changes smaller than TC.Models for predicting thermal properties were also discussed.Equivalent effective conductivity（EEC） was proposed to make H-J model suitable for hybrid particles and multimodal particle size distribution.
The SiC/A356/FeNi50 composite was fabricated by gas pressure infiltration. The interfacial region of the SiC/A356/FeNi50 composite consisted of FeNi50 reaction layer, A1 reaction layer and A1 alloy matrix. The main intermetallic compounds were （Fe,Ni）a（A1,Sih3 and （Fe,Ni）2（A1,Si）5 at the A1 reaction layer and FeNi50 reaction layer, respectively. The bending behavior versus different infiltration temperatures and holding times was also investigated. The bending strength at 670 ~C was the highest and close to the bending strength of A1 alloy （223 MPa）, and 46% of SIC/A356. The brittle intermetallic compounds existing at the interface induced the decreasing of the bending strength. The pores were reduced by adequate heating time due to the homogeneous temperature of preform, which was beneficial to improve the bending strength of the composite.
A titanium coating fabricated via vacuum vapor deposition for diamond/Al composites was used to improve the interfacial bonding strength between diamond particles and Al matrix,and the Ti coated diamond particles reinforced Al matrix composites were prepared by gas pressure infiltration for electronic packaging.The surface structure of the Ti coated diamond particles was investigated by XRD and SEM.The interfacial characteristics and fracture surfaces were observed by SEM and EDS.The coefficient of thermal expansion(CTE)of 50%(volume fraction)Ti coated diamond particles reinforced Al matrix composites was measured. The Ti coating on diamond before infiltration consists of inner TiC layer and outer TiO2 layer,and the inner TiC layer is very stable and cannot be removed during infiltration process.Fractographs of the composites illustrate that aluminum matrix fracture is the dominant fracture mechanism,and the stepped breakage of a diamond particle indicates strong interfacial bonding between the Ti coated diamond particles and the Al matrix.The measured low CTEs(5.07×10-6-9.27×10 -6K -1)of the composites also show the strong interfacial bonding between the Ti coated diamond particles and the Al matrix.
