Research progress on the strengthening and toughening mechanism of metal materials with gradient structure and its preparation technology

The development of industrial equipment requires lightweight and high performance, so it is necessary to replace the original alloy materials with high specific strength materials for the core parts of the equipment. However, the problem of strength-ductility/toughness trade-off during the preparation process of high specific strength metallic materials has hindered the independent research and mass production of key components in China. In recent years, the outstanding strength-toughness/ductility synergy exhibited by the gradient microstructure of metallic materials, along with the development of relevant preparation technologies, has indicated a development path for mass-producing lightweight components with high strength and toughness. In this paper, the strengthening and toughening mechanisms of gradient microstructures and the impact of different gradient on toughening behavior were reviewed based on the research on nanometal materials. Not only the plastic preparation techniques for achieving mechanical strengthening and toughening but also the influence of preparation process mechanical conditions on constructing gradient microstructures was discussed. These provided new insights for the engineering preparation of metallic materials with excellent strength-ductility/toughness synergy in gradient microstructures.