A comparative microstructural investigation of rapidly solidified Al-Fe and Al-Fe-Ce alloys

Rapidly solidified aluminum alloys are of considerable interest for applications in the aircraft industry. In the current study rapidly solidified Al-8 wt% Fe and Al-8 wt% Fe-3.4 wt% Ce alloys were produced by splat quenching. Microhardness measurements are reported for the two alloys for the different time-temperature aging conditions in the Intended service temperature range for these alloys. Microstructural investigations were carried out on the as cast alloys, as quenched splats and after aging for different time temperature aging conditions. Microstructural investigations were made using optical microscopy, SEM, TEM, and AEM. Metastable to stable phase transformations were mapped by x-ray diffraction techniques.

Results indicate that the metastable to stable phase transformation occurs much more slowly in the ternary alloy as compared to the binary alloy. The intermediate metastable precipitate, e¹, is shape modified with a different aspect ratio in comparison to the binary alloy. The dispersed phase coarsening was observed to be slower in the ternary alloy, suggesting that presence of cerium in aluminum plays a role in delaying particle coarsening.