Dislocation Emission and Formation of Prismatic Loop in Single Crystalline Aluminum under Indentation (Simulations by Molecular Dynamics)

Abstract

Recent new finding of unstable displacement burst observed in the relation between the indent load and indent depth of nanoindentation is much possible to be related to the collective dislocation emission. In the present paper, dislocation emission and prismatic dislocation loop formation of a single crystalline aluminum under nano-scaled indentation are simulated by the molecular dynamics. Effects of the stress distribution due to two different types of indenters and of the interatomic description by three different embedded atom type potentials are discussed with much emphasis. In result, the dislocations are emitted from the severely damaged surface atomic layer due to the indenter. Afterwards, the prismatic dislocation loops, which have the same gliding direction but not on the slip planes, are attained by both unstable reaction between the shear loops emitted from the surface and the cross slip mechanism.