Revealing the interface-mediated dislocation behavior and its role in delocalizing strain band in laminated aluminum

Abstract

This study investigated the plastic deformation behavior of fine-/coarse-grained laminated aluminum (Al) via in-situ tensile test coupled with digital image correlation (DIC) and electron backscatter diffraction (EBSD), aiming to unveil the relation between local strain behavior and dislocation mechanisms. The local strain analysis found that strain localization bands generating in hard but brittle fine-grained layers are effectively impeded under the constraint of neighboring coarse-grained layers. With the aid of novel misorientation mapping method, the dislocation structures, distinguished from those in the coarse grain interior, were found to be predominant within the propagation path of localized strain band. These interface-mediated slip systems, which are responsible for suppressing the strain band propagation, were further analyzed by integrating the dislocation structures and local orientation rotations. The dominant role of such mutual interactions between strain delocalization and dislocation behaviors in improving the strength-ductility synergy was also discussed. These findings are important for understanding the deformation behaviors of heterogeneous multi-layered metals, and also provide guidance for designing high-performance layered metals by regulating local strain behavior and underlying dislocation mechanisms.