Quasicontinuum study the influence of misfit dislocation interactions on nanoindentation
J. W. Li, H. B. Lu, Y. S. Ni and J. F. Mei
Computational Materials Science, 50, 3162-3170 (2011).

ABSTRACT
Multiscale simulations using the quasicontinuum (QC) method with the
embedded-atom method (EAM) potential are performed to examine the mechanical
response of Cu-Ag bilayer film during nanoindentation tests. An attempt is made,
from the viewpoint of collective interaction among misfit dislocations on the
interface, to account for the strengthening and weakening mechanisms
of interface on Cu-Ag bilayer film. The details of misfit dislocation
nucleation, motion and collective interaction on Cu/Ag and Ag/Cu interfaces are
discussed systematically, respectively. The investigation shows that the
property and performance of Cu-Ag bilayer film mainly depend on the mechanical
property of upper film. Both the strengthening and weakening effects are closely
related to the collective interaction among misfit dislocations on the
interface. Due to the pinning effect of interface on misfit dislocation, both
the local interface migration and the voids can be observed at the core region
of misfit dislocations. For nanoindentation on Cu/Ag bilayer film, the plastic
deformation is localized chiefly in the lower Ag substrate and the void will
disappear with the redistribution of misfit dislocations, which indicate that
there are distinct protective and strengthening effects of the upper Cu film on
the lower Ag substrate. While, for nanoindentation on Ag/Cu bilayer film, both
the upper Ag film and the lower Cu substrate experience plastic deformation and
the voids will not disappear, which imply that there are an obvious weakening
effect of the upper Ag film on the lower Cu substrate. In addition, the
multiscale simulation results are consistent with the experimental results.