REINFORCEMENT SHAPE EFFECTS ON THE FRACTURE-BEHAVIOR AND DUCTILITY OFPARTICULATE-REINFORCED 6061-AL MATRIX COMPOSITES

Particle shape effects on the fracture and ductility of a spherical an d an angular particulate-reinforced 6061-Al composite containing 20 pe t vol Al2O3 were studied using scanning electron microscopy (SEM) frac tography and modeled using the finite element method (FEM). The spheri cal particulate composite exhibited a slightly lower yield strength an d work hardening rate but a considerably higher ductility than the ang ular counterpart. The SEM fractographic examination showed that during tensile deformation, the spherical composite failed through void nucl eation and linking in the matrix near the reinforcement/matrix interfa ce, whereas the angular composite failed through particle fracture and matrix ligament rupture. The FEM results indicate that the distinctio n between the failure modes for these two composites can be attributed to the differences in the development of internal stresses and strain s within the composites due to particle shape.