Role of reinforcement content on the fracture behavior of DRA under dynamic loading

Discontinuously reinforced aluminum matrix composites (DRAs) are adequate candidates for substantial class of materials with improved strength, stiffness, fatigue behavior, and wear resistance. Despite these benefits, low impact resistance and damage tolerance restricted the application of DRAs. It is notable that all mechanical properties depend on the shape, size and significantly the volume fraction of second phases which control the fracture behavior of composites. In this research the effect of reinforcement concentration on the impact behavior of hot extruded Al6061-SiC was investigated. Therefore, one monolithic sample beside three types of composite, i.e. Al6061-5 , 10 and 15 vol.% SiC, were fabricated via powder metallurgy route. It was found that an increment on SiC content decreased the impact energy of composite by modifying the fracture surface of samples. Indeed, the enhancement of dislocation density at high strain rate intensified the probability of dislocation locking. By increasing the SiC content, this effect was got highlighted and eventuated in brittle fracture. In this case, the width of shear lips decreased and confirmed the restriction of plastic deformation in metal phase. This limitation in plastic strain was accompanied with modification in fracture surface at high magnification, i.e. an increment in SiC volume resulted in decrease in voids’ bands, as well as, enhancement in particle cracking within dimples.