Enhanced strength-ductility synergy in multilayered aluminum via integrating dual-heterogeneous structures

Tailoring multi-type or multi-scale heterogeneous structures offers a promising pathway to overcome the strength-ductility trade-off in metallic materials. In this study, a dual-heterogeneous structure is developed within AA3003/AA1060 multilayered aluminum via simply controlled annealing temperatures, synergizing bimodal grain distributions (fine/coarse grains with micro-scale contrast) within multilayered frameworks. Compared to the single multilayered sample, the dual-heterogeneous sample achieve a notable improvement in the uniform elongation (from 9.8 % to 15.5 %), with only a marginal reduction in yield strength (∼13 MPa). Comprehensive microstructural analyses reveal that tailored nano dispersoid redistribution within AA3003 layers enables preferential growth of partially recrystallized grains, responsible for the inclusion of the bimodal structure. By analyzing the dislocation structures upon the tensile deformation, it is found that the heterogeneous interfaces of bimodal structure can accumulate more geometrically necessary dislocations (GNDs) than conventional layered interfaces, also show a superior capacity of dislocation multiplications. These microstructural features can explain the enhanced work hardening capacity in the dual-heterogeneous structure. This work can contribute valuable insights into the design strategies for heterogeneous metals, aiming at a superior mechanical performance.