Characterization of the icosahedral phase in as-cast quasicrystalline Al65Cu20Fe15 alloy

Morphology features and microstructures of a quasicrystalline Al65Cu20Fe15alloy were studied using X-ray diffraction, scanning electron microscopy (SEM), electron probe microanalysis, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) techniques. A typical layer dendritic microstructure of the as-cast quasicrystalline alloy consisted of four phases: an Al71Cu5Fe24phase as a core of the dendritic structure, which was surrounded by a quasicrystalline Al60Cu26Fe14phase and a crystalline Al50Cu45Fe5phase being in the interdendritic regions, and a Cu-rich Al44Cu54Fe2phase. The quasicrystalline phase was characterized of three symmetries: five-, three-, and twofold. The Kikuchi diffraction patterns obtained from both SEM and TEM are very similar. It is shown that without the need to prepare thin film specimen, EBSD is an alternative method to characterize quasicrystals.