The present work reports the dynamic compressive strength (sigma(c)) of a dense (similar to 95%) coarse grain (similar to 20 mu m) alumina measured at 30 degrees C as a function of strain rates ((epsilon) over dot) ranging from 10(-5) to 5 x 10(-1) s(-1). The results showed a unique 40% enhancement of (sigma(c)) with the increase in ((epsilon) over dot). Extensive post mortem examination of fracture fragments obtained from the compressive failure tests by FESEM, TEM and HRTEM confirmed the formation of micro-cracks, shear bands, nanoscale cleavages and dislocations whose recurrence had increased with strain rate. Both shear induced microplasticity and nanoscale cleavages as well as dislocations had occurred concurrently yet independently during compressive fracture of coarse grain alumina even at very low strain rates. Based on these evidences a new compressive failure mechanism of alumina was proposed. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved
