Influence of interfaces on the mechanical behavior of SiC particulate-reinforced Al–Zn–Mg–Cu composites

In particulate-reinforced metal matrix composites (MMCs), geometrically necessary dislocations (GNDs) form in the vicinity of reinforcement/matrix interfaces. In this study, the hardness distribution across the interface was studied using nanoindentation with high spatial resolution, for composites treated under different aging conditions. The size of the GND punched zone, as determined from the hardness measurement, was found to be in agreement with that estimated by transmission electron microscopy (TEM). Mechanical characterization of bulk composites revealed a reduction in failure strain with decreasing punched zone size, while the strength of the composites was found to depend more on the intrinsic strength of the matrix alloy. These observations were interpreted in terms of the load transfer capacity between the matrix and reinforcement through the interface.