Achieving excellent mechanical and electrical properties in Al-Si alloy via heterogeneous lamella structure with high-density nanoprecipitates

With the increasing demands for material performance in modern industries, there is a growing need for aluminum alloys with high strength and good ductility. In addition, energy consumption in power transmission process makes developing transmission materials with high strength and outstanding electrical conductivity more urgent. Here, a heterogeneous lamella structure containing dense Si nanoprecipitates, which provides excellent mechanical and electrical properties, was intentionally introduced into a coarse-grained Al-1%Si alloy through solution treatment, heavy cold rolling, and subsequent annealing. The continuous 97.5 % cold rolled Al1%Si exhibits a yield strength of 276 MPa and a uniform elongation over 3 %. A further improved yield strength of 302 MPa, an ultimate tensile strength of 318 MPa, and a conductivity of 53.3 % IACS are achieved in the sample annealed at 150 degrees C for 1 h. The coarse size and different orientation of the original grains result in the heterogeneous lamella structure. The hetero-deformation induced hardening during tensile deformation offers an outstanding strain-hardening ability, delaying the onset of necking and enabling high strength and good ductility. The dense nanoprecipitates are the main reason for further improved strength and good electrical conductivity. Our results demonstrate the heterogeneous structure resulting in excellent comprehensive mechanical properties and offer a feasible method for preparing high strength and high electrical conductivity using Al-based dilute alloys.