Plastic deformation mechanism in nanotwinned metals: An insight from molecular dynamics and mechanistic modeling

An overview is given of the deformation mechanisms in nanotwinned copper, as studied by recent molecular dynamics, dislocation mechanics and crystal plasticity modeling. We highlight the unique role of nanoscale twin lamellae in producing the hard and soft modes of dislocation glide, as well as how the coherent twin boundaries affect slip transfer, dislocation nucleation, twinning and detwinning. These twin boundary-mediated deformation mechanisms have been mechanistically linked to the mechanical properties of strength, ductility, strain hardening, activation volume, rate sensitivity, size-dependent strengthening and softening in nanotwinned metals. Finally, discussions are dedicated to identifying important unresolved issues for future research.