ABSTRACT
Ductility of nanostructured metals has been a hot research topic for over a decade. Many strategies have been proposed to enhance the ductility of nanostructured metals, including pre-existing and deformation twins and second-phase precipitates, stacking faults, and high-angle grain boundaries. This chapter discusses the differences between ductility and plasticity, clarify some common misconceptions and confusions, and then briefly discuss recent progresses in improving the ductility of nanostructured metals. Plasticity can be usually measured under compressive stress since mechanical stability normally does not occur under such a loading condition. In cases where local shear-band-induced instability occurs during compressive testing, other deformation mode such as rolling could be used to evaluate the plasticity. Brittle materials typically have no mobile dislocations available to accommodate plastic deformation when deformed. Strain rate sensitivity may also play a significant rule in increasing ductility for some metals with low melting temperature. Ductility can be regarded as tensile plasticity and can only be measured using tensile test.
