Microstructures, mechanical properties and deformation mechanism of heterogeneous metal materials: A review

In recent years, a new type of fast emerging heterostructure materials (HSMs) has emerged in the field of metal materials. This material is composed of soft and hard regions with significant strength differences due to the heterogeneity of microstructure, crystal structure and composition. It can effectively break the inverted relationship between strength and ductility of traditional homogeneous materials, which mainly depends on the synergistic strengthening effect: hetero-deformation induced (HDI) strengthening and hardening. This paper adequately reviewed the heterogeneous deformation fundamentals, the microstructure characteristics and mechanical properties of various HSMs prepared by different processing methods. Meanwhile, we assess the mechanical behavior and influencing factors of the synergistic strengthening effect from the perspective of microscopic strain/stress, damage mechanism and key heterostructured parameters. In addition, the numerical simulations of HSMs are systematically revealed, which offers theoretical guidance for their quantitative design with the best mechanical properties. This paper aims to construct the relationships among the heterostructures, microscopic deformation mechanisms and macroscopic mechanical properties, provide a valuable reference for the optimal heterostructures, and explore crucial scientific issues that warrant further investigation.