Multi-scale characterization of spatially heterogeneous systems: implications for discontinuously reinforced metal–matrix composite microstructures

A new multi-scale technique is presented for characterizing the spatial distribution of second-phase particles in two-dimensional distributed multi-phase systems. The implications for the characterization of reinforcement distributions in discontinuously reinforced metallic matrix composite microstructures are discussed, along with results of the analysis both for simulated and experimental discontinuously reinforced aluminum (DRA) materials. A systematic variation in the degree of spatial heterogeneity is observed with increasing length scale. This result leads to the definition of the parameter LH or homogeneous length scale. The relevance of LH measured for a real DRA microstructure is then discussed in the context of statistical variations in mechanical properties such as tensile strength, ductility, and fracture toughness.