The formation of quasicrystals in Al-Cu-Fe-(M=Cr, Ni) melt-spun ribbons

The influence of Cr and Ni additions in rapidly-solidified Al-Cu-Fe alloys was investigated. Four compositions, namely, Al64Cu20Fe13Ni3, Al63Cu18Fe10Ni9, Al65Cu22Fe10Cr3 and Al67Cu20Fe5Cr8 were selected based on a methodology in which the average valence electron per atom (e/a) ratio of the ternary Al-Cu-Fe quasicrystal was maintained constant. Melt-spun ribbons of all four alloys were produced and then examined by X-ray diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy. The results indicate that the Al-Cu-Fe icosahedral quasicrystalline phase has limited solubility for Ni such that with increasing Ni content, the fraction of the quasicrystalline phase decreased drastically and two primitive B2 cubic phases were formed instead. Additions of Cr resulted in the formation of a decagonal quasicrystal at the expense of the icosahedral phase. At 3 at% Cr, both icosahedral and decagonal phases were observed, with the former having the major volume fraction. For the alloy containing 8 at% Cr, only the decagonal phase was observed. (C) 2017 Elsevier B.V. All rights reserved.