Atomistic simulations of fracture in nanocrystalline copper under high strain rates*

Structural features of nanocrystalline materials attract continuous attention due to their unique properties and prospects for various technological applications. In this work microscopic mechanisms of plasticity and fracture in nanocrystalline copper are considered at the atomistic level by molecular dynamics method. The EAM potential model [Y. Mishin et al // PRB 63 (2001) 224106] is used to describe interatomic potential. The initial structure is created by filling random Voronoi polyhedra with different orientations of lattice and subsequent equilibration. Three ways of the high strain rate ($10^{8}$ -- $10^{10}$ s$^{- 1}$) plastic deformation and fracture processes modeling are compared: hydrostatic and uniaxial strain and shock wave loading in the impacor-target model. The dependence of the results on the average grain size, orientation and shape is studied.