Phase diagram of the Al–Cu–Fe quasicrystal-forming alloy system

Abstract The formation and thermal stability of φ phase in as-cast, annealed and very slowly cooled samples have been studied by means of X-ray diffraction, metallographic investigations, differential thermal analysis and magnetothermal analysis. The results of the combination of these data indicate that the φ phase forms from the β phase by a solid-state polymorphous reaction at 650 °C, it is thermodynamically stable below the formation temperature and can be in equilibrium with i, η, β, ε, and ω phases. On the other hand, an ordered β structure (β′) is found in as-cast and moderately cooled alloys, this metastability is characterized by a suppression of φ phase formation during cooling.