Microstructural evolution and corrosion behavior of nanocrystalline FeAl synthesized by mechanical alloying

• FeAl.7 exhibits a fully dense microstructure without porosity.
• Consolidation pressing has no effect on the corrosion behavior of the Fe(Al).
• FeAl.7 and FeAl.7/250 exhibit nearly similar corrosion behavior of recycled Al.

A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The mechanically alloyed powders were consolidated at room temperature under pressures of 5 and 7 GPa, then annealed at different temperatures for 2 h. The phase transformations occurring in the bulk Fe(Al) solid solutions were studied by X-ray diffraction. Scanning electron microscopy was employed to examine the morphology of the different samples. Fully dense disks with homogenous microstructure were obtained and the bulk materials show grain sizes of 20–40 nm. Electrochemical techniques were used to investigate the effect of consolidation pressure and annealing temperature on the corrosion behavior of Fe(Al) solid solution. The consolidation pressing has no effect on the corrosion behavior of the samples. Lower values for corrosion potential (Ecorr) and pitting potential (Epit) were obtained after annealing at higher temperature (450 and 650 °C). Pitting was initiated preferentially in the metastable intermetallics new phases.