Effect of layer thickness on the enhanced strength and ductility of laminated Ti/Al composite

The layer thickness has been reported to play a crucial role in laminated metal composites (LMCs). In this work, Al/Ti/Al LMCs with varying Ti layer thickness but a constant number of interface were fabricated by hot rolling and annealing to explore the effect of layer thickness on the enhanced strength and ductility. Ex-situ electron backscatter diffraction (EBSD) and digital image correlation (DIC) techniques were used to reveal the plastic deformation mechanisms. With the decrease of the Ti layer thickness, the extra strength and elongation caused by the layered structure increase continuously until the layer thickness is reduced to ∼0.6 mm. When the best combination of strength and elongation is achieved, the width of the interface affected zone (IAZ) in the Ti layer reaches ∼0.3 mm, which is roughly half of the layer thickness of the Ti layer. Within the IAZ of the Ti layer, more pyramidal and basal slips are activated compared with that in the central part, which contributes to the increase of strain delocalization efficiency. In addition, the geometrically necessary dislocations (GNDs) also exhibit gradient distribution following the strain gradient, resulting in hetero-deformation induced (HDI) strengthening and hardening. This work further enriches the knowledge of achieving excellent strength-ductility synergy in LMCs.