Microstructure and mechanical properties of rare-earth-modified Al−1Fe binary alloys

Rare-earth (RE) mischmetal modification, homogenous annealing and rolling techniques were used to improve the microstructure and mechanical properties of an Al−1Fe alloy. Al3Fe, Al6Fe and Al3Ce intermetallic phases were found in the RE-modified alloys in the as-cast state. The RE modification refined the α-Al grains, resulting in a divorced eutectic and the formation of the Al−Fe phases in the forms of discontinuous networks, flakes and particles. Elemental La dissolved in the Al−Ce phases but did not dissolve in the Al−Fe phases. The dissolution of elemental Ce in the Al−Fe phase along with homogeneous annealing caused the claw-like Al−Fe phases to transform into short flakes and particles, which were uniformly distributed in the matrix by the rolling processes. A 0.3 wt% RE modification had the optimized effect on the microstructure and mechanical properties, while a 0.4 wt% RE addition resulted in the aggregation of the Al−Ce particles, which then deteriorated the mechanical properties of the alloys.