Synthesis of an Al-based Al–Cr–Co–Ce alloy by mechanical alloying and its thermal stability

Amorphous and nanocrystalline phases generated in an elemental blend of Al94.5Cr3Co1.5Ce1 composition (at.%) in the course of mechanical alloying (MA) have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). It has been reported that rapid solidification processing (RSP) of the same composition generates a finely mixed unique structure consisting of nanoscale icosahedral (I) particles surrounded by a thin Al phase [A. Inoue, Nanostruct. Mater. 6 (1995) 53–64]. In contrast, MA of Al94.5Cr3Co1.5Ce1 composition carried out in the present study shows the formation of Al-based solid solutions along with partial amorphisation. It emerges that during MA a wide difference in the atomic size of the alloying elements in solid solution plays a pivotal role in the amorphous phase formation. The possible causes of the difference in microstructure generated by MA and RSP have been discussed. The thermal stability of the mechanically alloyed product has also been investigated by a differential scanning calorimeter (DSC) and XRD.