Enhancing Strength and Electrical Conductivity in Al–Zr–Sc Conductor Alloys Through Sn and Sr Microalloying and Two‐Step Aging Treatment

Trace additions of Sn (0.05 and 0.15 wt.%) and Sr (0.006 and 0.013 wt.%) combined with a novel two‐step aging treatment were introduced into Al–Zr–Sc conductor alloys to investigate their effects on microstructure and mechanical properties. The additions of Sn or Sr, together with two‐step aging, improved the mechanical strength and electrical conductivity (EC) of the alloys. In the Sn15 alloy, two‐step aging enhanced microhardness, ultimate tensile strength, and EC to 78.3 HV, 216 MPa, and 58.3% IACS (International Annealed Copper Standard), respectively, compared with 74.2 HV, 206 MPa, and 57.5% IACS after conventional one‐step aging. Similarly, the Sr13 alloy exhibited improved properties, with 83.2 HV, 227 MPa, and 58.0% IACS after two‐step aging, versus 78.3 HV, 215 MPa, and 57.5% IACS with one‐step aging. These improvements—5.5 HV, 10 MPa, and 0.8% IACS for the Sn15 alloy; 5.2 HV, 12 MPa, and 0.7% IACS for the Sr13 alloy—are primarily attributed to the precipitation of a larger number of fine Al 3 (Sc, Zr) strengthening precipitates. Early‐stage Al 3 (Sc, Zr) precipitation was observed in the Sn15 alloy after the first‐step aging at 300°C for 4 hr. In the Sr‐containing alloys, enhanced strengthening was also associated with increased dislocation resistance in the presence of stacking faults. The trace additions of Sn or Sr, combined with two‐step aging, offer a cost‐effective strategy for developing the next generation of thermally stable, high‐performance conductor alloys.