Role of GNDs in bending strength gain of multilayer deposition generated heterostructured bulk aluminum

Gradient structured materials have been proven to have excellent mechanical properties, such as strength–ductility synergy and excellent strain hardening. In this study, the deformation mechanism of heterostructured bulk aluminum with submicron deformation mechanisms was investigated using a mechanism-based strain-gradient plasticity model, whose gradient information was obtained using a discrete gradient computation method. The model was then used to simulate bending of the material and investigate extra strain hardening. The microstructure of the material was characterized using electron backscattered diffraction analysis. The complicated dislocation reactions occurring during the deformation of multilayer deposition material were determined from the simulation results. The distribution and evolution of geometrically necessary dislocations (GNDs) were numerically determined. The simulation results demonstrate that the GNDs and the number of material gradient cycles have a direct influence on plastic hardening. Inclusion of more layer periods in the material resulted in additional large-scale strain gradient across its thickness. The results of this study advances the understanding of the underlying deformation mechanisms that control ductility and strengthening over periods and gradients and provides the possibility of obtaining multilayer materials with exceptional mechanical properties.