Study On Fabrication And Properties Of Silicon Carbide Particle Reinforced Aluminum Matrix Composites

High volume fraction Silicon Carbide particles reinforced aluminummatrix composite（SiC_p/Al） is one of potential materials applied in electronicpackaging for its excellent properties such as low density, high thermal conductivity,lower thermal expansion coefficient etc. Researching the structure and properties ofSiC_p/Al is of great importance, for preparing the electronic packaging materialswith excellent properties. In this paper, the influence of the Si content andmorphology on the structure and properties of SiC_p/Al composites and theinterfacial stability of composite with a low Si content were investigated.The SiC_p/Al composite produced by pressureless infiltration of liquidaluminum alloy into SiC preform was studied. The main research results are asfollowing:The distribution of Si is the same in the excess remainint solidificatedaluminium alloy after infiltrion and the SiC_p/Al composite,however, themorphology of Si phase in the excess remainint solidificated aluminium alloyafter infiltrion is different from it in the SiC_p/Al composites.When thecontent of Si is7%, Si phase in aluminum alloy exhibits mainly small roundedshort rod in shape and particles distributed in aluminum alloy, whereas in thecomposites the morphology of Si phase is still smaller with unevendistribution.When the content of Si is12%, Si phases in aluminum alloy exhibitsmain thick sheet or needle-like in shape and exhibits hook and short strip in shapeprecipitated along the boundary of SiC particle.When the content of Si is14%, Siphase in the aluminum alloy exhibits big or small block in shape, however Si phasein the composites exhibits short particle or short strip in shape dispersed in both Aland SiC. Because of the difference of the Si morphology and content in thecomposites,the bending strength of the composites accordingly vary, the highest forcontent of7%Si, second for14%Si, and minimum for12%Si.When Si content is7%in aluminum matrix of the composite, and its infiltrationtemperature is higher than800oC and the composite is interfacial instable with theemergence of hydrolysis powders. As the infiltration temperature between735oCand800oC, the composite has no Al₄C₃phase and hydrolysis powder. The bending strength of SiC_p/Al composites gradually increases with infiltrationtemperature from735oC to850oC, and not reduced by the formation of Al₄C₃phase.The SiC_p60%/AlSi7Mg8composites （65%SiC volume fraction） was preparedby pressureless infiltration of liquid aluminum alloy melt into SiC preform （shapedby the SiC power with the size of F240and F600） from bottom to up. The compositesmicrostructure is uniform with a bending strength of308³84MPa, the thermalconductivity of160¹70W/m^-1·k^-1, and an average thermal expansion coefficient is5.57×10^-6k^-1（25oC¹00oC）, which meet the requirements of electronic packaging.