Dual gradient microstructure to simultaneously improve strength and electrical conductivity of aluminum wire

High strength and high electrical conductivity are needed for the usage of aluminum wire in high-voltage lines. Strength and electrical conductivity are contradictory in metallic materials. Improving strength comes with the sacrifice of electrical conductivity. Here we produced a dual gradient microstructure to improve the strength of aluminum wire without compromising electrical conductivity. Aluminum wires with gradient microstructures and dual gradient microstructures were processed through clockwise torsion and subsequent anti-clockwise torsion. Compared with the gradient microstructural aluminum, aluminum with dual gradient microstructures possesses higher strength and higher electrical conductivity. Microstructural characterizations and numerical simulations further reveals that dual gradient grain size provides extra strain hardening and less electrical resistivity. This explains the high strength and high electrical conductivity in aluminum wire with dual gradient microstructure.