Hypervelocity impact induced deformation modes in α -alumina

Hypervelocity impact deformation mechanisms of α -alumina are studied using 540× 106 atom molecular dynamics simulation on massively parallel computers. The projectile impact on the (0001) surface of α -alumina at 18 kms exhibits a fundamentally different symmetry of the deformation patterns from those under lower strain rates. The simulation reveals a sequence of atomistic deformation mechanisms following localized melting and amorphization. These include pyramidal slips, basal slips and twins, rhombohedral twins, and twins along the {0 1- 11}. Some of these deformation patterns are not observed under lower impact velocities. © 2007 American Institute of Physics.