Experimental study of the effect of the anisotropy of orientation of the reinforcing particles on the tensile properties of aluminium matrix composites reinforced with alpha-alumina platelets

This paper is focused on the effect of the distribution of the orientation of reinforcing particles having the shape of platelets on the tensile properties of aluminium matrix composites. To obtain different distributions of orientation, the initially isotropic composites were submitted to two secondary fabrication processes: rolling and extrusion. The conventional tensile tests performed on the isotropic, rolled and extruded composites showed that rolling and extrusion modify the initial work hardening rate, the flow behaviour at high strains and the strains to failure of the composites. The decrease in the initial work hardening rate of the rolled and extruded composites was attributed to the alignment of the platelets along the rolling or extrusion direction, which reduces the forest interaction contribution to the work hardening. The increased strains to failure were attributed to the fact that the three types of composite are characterized by three different damage mechanisms, as was shown by in-situ tensile tests performed in a scanning electron microscope. These mechanisms do not have the same incidence on the ductility of the composites.