Effects of SiC volume fraction and aluminum particulate size on interfacial reactions in SiC nanoparticulate reinforced aluminum matrix composites

The SiC nanoparticulate reinforced Al-3 0 wt % Mg composites were fabricated by combining pressureless infiltration with ball-milling and cold-pressing technology at 700 degrees C for 2 h The effects of SIC nanoparticulate volume fractions (6% 10% and 14%) and Al particulate sizes (38 mu m and 74 mu m) on interfacial reactions were investigated by SEM TEM and X-ray diffraction The results show that the MgO at the interface between SIC nanoparticulate and molten Al can provide a barrier for the diffusion of Si C and Al Using Al particulate (74 mu m) as raw material the Al4C3 phase was not found in the composites containing 6 vol % and 10 vol % SIC but presented in the composites containing 14 vol % SIC When SIC content up to 14 vol % the products of MgO around SIC nanoparticulate are not enough to provide effective protection from the reaction between SIC and molten Al therefore the diffusion of Si C and Al can take place to produce Al4C3 and Si phases Using 38 mu m Al particulate as raw material the fine Al particulate possesses the high reaction activity and can easily be embedded Into the gap among the big Mg particulate segregated at the Interface resulting in the appearance of exposure surface of SiCp to the Al and the forming of diffusion channels for the atomics C Si arid Al So the formations of Al4C3 and Si phases were occurred Crown Copyright (C) 2010 Published by Elsevier B V All rights reserved