| Abstract Scope |
The shock deformation and spall failure behavior of layered FCC/BCC multiphase metallic materials usually rely on the ability of the interface to control the dislocation evolution behavior, which is determined by the interface microstructure, i.e., orientation-relationship, spacing, impedance mismatch, etc. The recent capabilities to synthesize FCC/BCC laminate microstructures enable the understanding of the competing mechanisms of dislocation slip, deformation twinning, and phase transformation under dynamic loading conditions. Large scale molecular dynamics (MD) simulations are carried out to investigate the spallation behavior of various possible Cu/Fe laminate microstructure with variation in size and orientation relationship of interfaces. The shock response behavior of this nanolaminate is characterized by deformation twinning and (BCC→HCP) phase transformation. The ductile failure behavior under the dynamic loading conditions transpires due to the interaction of reflected waves, forming triaxial tensile stresses, and is characterized by nucleation, growth, and coalescence of voids. This talk discusses the role of interface microstructure on the shock wave propagation and reflection behavior during shock compression and the contributions to plasticity from twinning and phase transformation behavior. The spacing of interfaces, as well as the loading conditions (shock pulse), modifies the wave reflection behavior and results in modifications in void nucleation at the interface and in the FCC and BCC phases. The MD snapshots are characterized to identify the twining/de-twinning mechanisms as well as the reverse phase transformation mechanisms (HCP→BCC) and the role of these mechanisms on damage nucleation and evolution behavior. The effect of orientation-relationship and impact velocity on the deformation response and the spall strength will be presented. |