Abstract：Metallic materials have been widely used in aviation, aerospace and civil industries. To achieve a metallic material with high yield strength and good ductility has become an important issue in the disciplines of materials, physics and mechanics. The traditional strengthening methods, such as strain hardening, solid-solution alloying, phase transformation, grain refinement, and second-phase dispersion strengthening, although can improve the strength, would greatly weaken the plastic properties. In recent years, experimental studies have demonstrated that interface design and microstructural control enable the metallic materials to be prepared with a good combination of high yield strength and high ductility. It has been proved that the interactions between the dislocations and various interfaces and the weakened stress concentration through the optimization of microstructures are the primary mechanisms of strengthening and toughening. On the basis of experimental observations, researchers applied the atomic methods to analyze the plastic deformation in the metallic materials with high strength and high ductility quantitatively, and gave insights into the strengthening mechanisms and failure behaviors. On the other hand, the mechanism-based theoretical model and the finite element approach were developed to describe the mechanical behaviors of novel metallic materials with excellent mechanical properties. In this work, we review the experimental and theoretical studies on the mechanical properties such as strength and ductility, and plastic deformations of nanotwinned metals and gradient-nanostructured metals; and put forward the prospect of optimization of high yield strength and high ductility for novel nanostructured metals.
2019, Vol. 40 
