Abstract :
Mounting evidence is pointing to some
emerging novel behaviors of metals with ultrafinegrain
(UFG) and/or nanocrystalline (NC) microstructures.
One such novel behavior is related to the
thermodynamic and kinetic aspects of plastic response
in the UFG/NC regime. Two inter-related parameters,
viz., the strain rate sensitivity (SRS) and the activation
volumes of plastic deformation, are used as fingerprints
for the thermodynamics and kinetics of plastic deformation.
Changes of these parameters with grain size
may indicate transition of plastic deformation mechanisms.
Therefore, investigations of these phenomena
may bring out new strategies for ingenious design and
synthesis of UFG/NC materials with desirable properties.
In this article, we present a critical review on the
experimental results and theories associated with the
SRS of UFG/NC metals with different lattice structures,
and the influences on some constitutive
responses.
