Role of Er element and two-stage heat treatment in a rheo-extruded Al–Sc–Zr alloy: Balance strength and electrical conductivity

• A high strength-conductivity Al–Sc–Zr–Er alloy was obtained via continuous rheo-extrusion and two-stage heat treatment. • Er addition promoted the precipitation of Sc and Zr atoms, causing an improvement in comprehensive performance. • The enhanced strength was associated with the formation of nanoscale Al 3 (Er, Sc, Zr) precipitates. • Solid solution, precipitation and grain boundary played a significant role in determining the electrical conductivity. Strength and electrical conductivity are critical properties for aluminum (Al) alloy wires employed in overhead transmission lines. Achieving a combination of high strength and high conductivity remains a challenge in the development of Al alloys. In this work, the effects of aging treatments on the microstructure and properties of Al–Sc–Zr (–Er) alloys prepared by continuous rheo-extrusion (CRE) were investigated through comprehensive microstructural characterization and property evaluation. The results after aging at 320 °C, there was an increase in number density for the precipitates, suggesting that erbium (Er) had an ability to promote the precipitation of Al 3 (Sc, Zr) phases. Furthermore, the Er enhanced the aging response, peak hardness, tensile strength, and conductivity. Two-stage heat treatment improved the precipitation kinetics and conductive properties. Due to the formation of coherent nanoscale precipitates with L1 2 structure in the matrix, a high tensile strength of 182 MPa and a high conductivity of 61.5 % IACS were obtained, which was superior the reported similar alloys. Precipitation caused by Er helps reduce the detrimental impact of solute atoms on conductivity and also generate a good strengthening effect. This work provides an insight into property regulation for the high strength-conductivity Al alloys via short processing technology.