Profound strengthening and toughening effect of reinforcement aspect ratio in composite with network architecture

Abstract

Reinforcement aspect ratio is a fundamental parameter that affects the properties of metal-matrix composites (MMCs). Here particle- and whisker-reinforced aluminum composites with network reinforcement distribution were modeled to reveal the effects of aspect ratio on the deformation and fracture behaviors and thus mechanical properties. The results showed that the modulus and yield strength exhibited a U-shaped dependence on the aspect ratio of reinforcement because the load-bearing capacity of reinforcement showed a balance between aspect ratio and local volume fraction in the network architecture. For SiCp/Al composite with network architecture, particles in network layers parallel to external load exhibited higher stress (750–1000 MPa); while in SiCw/Al, the whiskers in perpendicular layer bore higher load, which increased with the aspect ratio of the whisker. Furthermore, the fracture elongation (εfxx) of the network composites increased with reinforcement aspect ratio. SiCp/Al composite showed a smaller εfxx and brittle fracture behavior. This is contrary to the SiCw/Al network composite, which experienced a much larger εfxx and ductile fracture due to macro-interfacial decohesion behavior between SiCw rich and lean areas.