Characterization of the icosahedral quasicrystalline phase in rapidly solidified Al–Cu–Fe alloys

Abstract

Abstract The present research aimed to characterize the microstructure of icosahedral quasicrystalline phase (i-phase) in different chemical compositions of Al–Cu–Fe alloys. The ternary alloys with the nominal compositions of Al70Cu20Fe10, Al65Cu20Fe15 and Al63Cu25Fe12 (at%) were rapidly solidified by melt-spinning technique. The melt-spun ribbons were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). According to the XRD results, diffraction patterns of Al70Cu20Fe10 alloy showed the presence of the i-phase together with tetragonal θ-Al2Cu phase. However, XRD pattern of the melt-spun Al63Cu25Fe12 alloy showed the formation of i-phase together with a small amount of β-phase. The single quasicrystalline phase was observed only in the rapidly solidified Al65Cu20Fe15 alloy. The SEM examinations showed that the melt-spun Al70Cu20Fe10 and Al63Cu25Fe12 alloys composed of i-phase with an average grain size of 1–5 μm. However, for the Al65Cu20Fe15 alloy, the quasicrystalline particles in the star-shape dendritic formations were observed. The melting point of i-phase was determined as 890 °C by DTA examinations.