Effect of microstructure on the fracture mechanisms of SiC/Al composites obtained by dynamic compaction

SiC/Al composites obtained by dynamic compaction of powders with different contents of SiC particles were studied to determine the effect of the microstructure on the fracture mechanisms and tensile properties. Optical and scanning electron microscopy observations were performed on fractured surfaces, on both perpendicular to cracking planes and on fractured edges. The mechanical strength was analyzed in terms of the microstructure and fracture surface observations. The main results of this study have shown that the mechanical strength usually decreases when intergranular cracking is present on the fracture surfaces. Intergranular cracking was observed when a weak bonding exists between the aluminum powder and the SiC particles, or by the presence of melting zones which are related to the compaction process.