Heterostructured Metallic Materials: Plastic Deformation and Strain Hardening

Strong and tough metallic materials are desired for light-weight structural applications in transportation and aerospace industries. Recently, heterostructures have been found to possess unprecedented strength-and-ductility synergy, which is until now considered impossible to achieve. Heterostructured metallic materials comprise heterogeneous zones with dramatic variations (> 100%) particularly in mechanical properties. The interaction in these hetero-zones produces a synergistic effect wherein the integrated property exceeds the prediction by the rule-of-mixtures. More importantly, the heterostructured materials can be produced by current industrial facilities at large scale and low cost. The superior properties of heterostructured materials are attributed to the heterodeformation induced (HDI) strengthening and strain hardening, which is produced by the piling-up of geometrically necessary dislocations (GNDs). These GNDs are needed to accommodate the strain gradient near hetero-zone boundaries, across which there is high mechanical incompatibility and strain partitioning. This paper classifies the types of heterostructures and delineates the deformation behavior and mechanisms of heterostructured materials