Mechanical and microstructural characterisation of Al-SiC composite material obtained by dynamic compaction

Al-SiC composites produced by explosive compaction are analysed in the as-compacted condition. The SiC particles used as reinforced had an average size about 75±3 μm. Mixtures with 10, 20, 30 and 50 weight percent of SiC were prepared. Physical characterization was based on density determinations. Microstructural analysis was based on pores, phase percentage, and particle distribution. These data were related to mechanical behavior. Mechanical characterization was based on elasticity modulus, strength, microhardness and fractography on tensile specimens. Metallographic and fractographic results show that mechanical strength decreases with intergranular cracking percent on fracture surface. Intergranular cracking was found to be promoted by weak bonding between aluminum and SiC particles, or by the presence of local melting zones, related to compacting process. Physical, mechanical and microstructural characteristics of the composites in terms of E/ρ and σ/ρ ratios were established. It was for that the Al-20%SiC mixture had the best balance of properties. It is concluded that dynamic compaction offers possibility to process these kinds of materials, however, sintering would be needed to improve the quality of inter particle bonding.