Deformation kinetics in Cu/Ta nanoscale multilayers

Intensive research has been carried out on two key parameters important for interpreting the deformation kinetics of nanocrystalline metals, i.e., strain rate sensitivity and activation volume. Other than nanocrystalline metals, however, only a few recent studies focus on evaluating the two parameters for nanoscale multilayers that also possess nanoscale grain size. Using transmission electron microscope and nanoindentation test, we study the deformation behavior of nanoscale Cu/Ta multilayers having modulation period of 140 nm and 18 nm, respectively. The microstructure, grain size and strain rate sensitivity of the nanoscale multilayer subjected to nanoindentation are examined to explore its deformation mechanisms. It is established that the strain rate sensitivity of nanoscale Cu/Ta multilayers differ from those of nanocrystalline metals. The implications of these findings for the mechanical properties of nanoscale multilayers are discussed.