Formation of a single quasicrystalline phase in an Al₅₅Cu_25.5Fe_12.5Be₇alloy

An alloy with a single quasicrystalline icosahedral phase (I phase) can be produced by partial replacement of Al with Be (7at.%) in an Al62Cu25.5Fe12.5. alloy. The I phase nucleates first and then grows in a dendritic manner and the remaining liquid solidifies into the metastable t phase at a later stage of solidification during conventional casting with a Cu mould. With a lower cooling rate (crucible cooling), the liquid melt solidifies into an almost single I phase without heat treatment. The present study shows that the addition of Be stabilizes the I phase and expands the I-phase region. The Al55Cu25.5Fe12.5Be7I phase exhibits a highly ordered F-type structure like the Al-Cu-Fe I phase, and the intensities of the superlattice peaks in the electron or X-ray diffraction patterns do not vary on the addition of Be.