investigationofmechanicalbehaviorofinterfacesinnanostructuredmetals

When grain sizes of crystals are down to nano-scale, the so-called nanocrystalline materials exhibit distinct physical properties in contrast to their conventional counterparts. The strength and plastic deformation mechanisms were among the most broadly investigated properties from mechanical society. Since deformation and pre-mature failure in interfaces (including grain boundaries, twin boundaries, and interfaces between different media) could be the origin of lov'r ductility in nanocrystalline materials, the effort to evade the strength-ductility tradeoff dilemma in nanocrystalline materials, by tuning their interfacial structures/properties, is usually called as interfacial engineering. Twin boundaries stand out among all possible boundary structures for their capability to enhance strength and retain ductility of crystalline metals. In this paper, current understanding about the mechanical behavior associated with interfaces in nanostructured metals is reviewed, with a focus on the strengthening mechanisms played by twin/grain boundaries and current physical models to shed light on the size-effect induced by grain sizes and twin thicknesses