Microstructural Changes Associated with Annealing of Melt Spun Al<SUB>65</SUB>Cu<SUB>20</SUB>Fe<SUB>15</SUB>

Abstract

For rapidly solidified Al–Cu–Fe quasicrystals, detailed metallographic investigation on the stability of the quasicrystalline phase has been carried out. It has been shown that the quasicrystalline phase itself shows distinct changes in morphological features. Additionally the quasicrystalline phase is not entirely stable at 873 K, as has hitherto been believed. It transforms partially to a crystalline phase accompanied by repartitioning of solutes. The studies of repartitioning of the solute elements and diffraction of the transformed phases show that the product phase is the same as the coexisting crystalline phase found in small quantities in the as spun ribbons. An examination of the faceted interfaces between the quasicrystalline and crystalline phases suggest a transformation towards equilibrium state. The observed changes are related to the defect state in the quasicrystalline phase.