Dynamics and kinetics of dislocations in Al and Al-Cu alloy under dynamic loading

The paper is focused on investigation of the mechanisms and kinetics of plastic deformation of alloys under high-rate loading (at the strain rates >10(5) s(-1)). To study alloy behavior under these conditions the multiscale approach was developed. It comprises molecular dynamics (MD) calculations of dislocation mobility and continuum mechanics model, which describes elastic-plastic deformation, kinetics and dynamics of dislocations. Dislocation velocities as functions of the applied shear stress are calculated using MD data in a wide temperature range up to the melting point. Velocity-dependent drag coefficient is introduced by means of approximation of the obtained data. The paper includes the analysis effect that Guinier-Preston zones have on dislocation motion. The obtained results are used to evaluate temperature dependence of dynamic flow stress and evolution of dislocations subsystem under shock loading. Data on attenuation of elastic precursor calculated for Al is in good agreement with the experiments. Simulation of precursor decay in Al-Cu alloy demonstrates qualitative agreement with experimental data. (C) 2013 Elsevier Ltd. All rights reserved.