Effect of pre-torsion on the strength and electrical conductivity of aluminum alloy wire

Aluminum alloy wires with higher strength and better electrical conductivity are demanded in electrical engineering. Pre-torsion was employed to process aluminum alloy wire for the improvement of its properties. Uniaxial tensile and electrical tests show that simultaneous improvements of strength and electrical conductivity were achieved in the pre-torsioned aluminum alloy wire at a maximum shear strain of 0.27. Microstructural observations reveal that pre-torsion induces the formation of nanoscale rod-shaped beta' particles and the sizes of nanoscale precipitates increase with the maximum shear strain of pre-torsion. Based on the experimental results, a theoretical model is proposed to reveal the underlying mechanisms. The small nanoscale precipitates can contribute to the improvement of strength and electrical conductivity. The large size of nanoscale precipitates leads to the low strength and poor electrical conductivity. This is attributed to the weak strengthening and strong electron scattering in large nanoscale precipitates.