(1. School of Material Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China) (2. Northwest Institute for Nonferrous Metal Research, Xi‘an 710016, China)
Nanostructured metallic materials prepared by severe plastic deformation (SPD) techniques not only have unique microstructure, but also demonstrate obviously different mechanical properties compared with conventional coarsegrained (CG) materials. In this paper, SPD techniques were divided into block nanocrystallization techniques and surface nanocrystallization techniques according to the difference of refinement parts. The relatively mature SPD techniques and the microstructure refinement principle of two types of SPD techniques were outlined. The microstructure characteristics and grain refinement mechanism of nanostructured metallic materials prepared by SPD technology were summarized. The recent progress on mechanical behavior of nanostructured metallic metals worldwide was reviewed, in terms of strength, plasticity and strain hardening, fracture mechanism and fatigue property. In addition, the future research direction of nanostructured metallic materials in the aspect of its grain growth and structural stability was also discussed, in order to provide theoretical support for developing nanostructured metallic materials with high strength and excellent structural stability.