Rate-dependent behavior of hierarchical Al matrix composites

We present the rate-dependent constitutive response of hierarchical Al matrix composites which comprise a bi-modal distribution of Al in fine (nanocrystalline Al containing micro-sized B4C particles) and coarse (micro-grained Al) grain regimes. The strength of these composites is improved by various strengthening mechanisms. Shear localization is observed to be the primary failure mode. Compared to quaistatic loading, significant increase of strain to failure is observed at high strain rates. Varying rate-sensitivity is observed with different amount of B4C particles.