Quasistatic and dynamic compression of aluminum-oxide particle reinforced pure aluminum

Pure aluminum matrix composites reinforced with 40–55 vol.% Al2O3 particles of various sizes (5, 10, 29, and 58 μm) are produced by gas-pressure infiltration. Comparison of compressive flow stresses of these composites at quasistatic and dynamic strain rates shows that, in accord with the literature, the increase in flow stress of dynamically compressed composites results from the sensitivity of the matrix to strain rate. The accumulation of damage in the composites is quantified through high-precision density measurements. Damage accumulates primarily as a function of strain due to particle cracking followed by separation of the broken-particle segments and, to a lesser extent, by matrix cavitation. Composites reinforced by smaller particles have a higher flow stress, lower strain-rate sensitivity, and accumulate less damage, while a greater concentration of reinforcement increases the flow stress, strain-rate sensitivity, and the rate of damage accumulation.