Effect of coated B 4C reinforcement on mechanical properties of squeeze cast A356 composites

Abstract

In the present study, attempts were made to coat the B 4C powders with TiB 2via a sol-gel process, and then squeeze cast A356 matrix composites reinforced with coated B 4C particles were fabricated. X-ray diffraction studies also confirmed the existence of boron carbide and some other reaction products such as TiB 2, AlB 2and Al 3BC in composite samples. It was observed that the amount of porosity increased with increasing the volume fraction of composites. Tensile behavior and hardness of unreinforced alloy and composites were evaluated. It was noted that the elastic constant, strain-hardening and UTS of the metal matrix composites (MMCs) were higher than those of the un-reinforced Al alloy and increased with increasing of coated B 4C content. The strengthening of particulate reinforced metal-matrix composites is associated with a high dislocation density in the matrix due to the difference in coefficient of thermal expansion between the reinforcement and the matrix.