Microstructure Modification and Property Enhancement of Al-0.5Fe Alloy via Equimolar La/Ce Co-Doping: Mechanisms and Composition-Dependent Effects

The effects of equimolar La/Ce co-doping (0–0.4 wt.% of each element) on the microstructure, mechanical properties, and electrical conductivity of the Al-0.5Fe (8176) conductor alloy were investigated in the as-cast, cold-drawn, and annealed (300 °C, 2 h) states. La/Ce additions refine the as-cast eutectic cells and modify the detrimental Al13Fe4 intermetallic from coarse plate-like to fine spheroidal particles. At 0.3 wt.% La + 0.3 wt.% Ce (0.3LC), the annealed wire reaches a peak elongation of 16.7% (+42.7% relative to the rare-earth-free alloy), while its electrical conductivity rises from 59.87 to 61.81% IACS. The conductivity increase is explained by a solute-scavenging mechanism: La and Ce bind Fe and Si impurities into stable Al-RE intermetallics, reducing solute-induced electron scattering in the α-Al matrix. At the same time, thermally stable Al-RE dispersoids pin subgrain boundaries during annealing, retard recrystallization, and preserve the fine-grained structure that benefits ductility. Both effects originate from the same RE addition. This coupled scavenging–pinning pathway breaks the usual trade-off between conductivity and ductility and defines an optimal composition range for high-performance Al-Fe conductor alloys.