Preparation and characterisation of melt-spun Al-Cu-Fe quasicrystals

The icosahedral ψ-Al65Cu20Fe15 phase forms by a peritectic reaction between the primary β-AlFe phase and the liquid, as the temperature decreases. At the later stages of cooling, the monoclinic λ-Al13Fe4 phase and the tetragonal θ-Al2Cu phase are formed in the cast alloys, as a result of peritectic reactions. In the rapidly solidified alloys, the formation of the tetragonal θ-Al2Cu phase and, in the case of alloy Al60Cu25Fe15, the monoclinic λ-Al13Fe4 phase is avoided, apparently due to high degree of undercooling. Thus, the production of single-phase quasicrystalline ribbons is not possible by the melt-spinning process, at least by using the cooling rate of 5-7×104 °C/s. In addition to phase selection, the degree on undercooling influences, for example, the composition of the ψ-Al65Cu20Fe15 phase and the grain morphology in melt-spun ribbons.