Stability of quasicrystalline phase in Al–Cu–Fe, Al–Cu–Co and Al–Pd–Mn systems by high energy ball milling

Abstract

The stability of the quasicrystalline phase present in as-cast Al₆₅Cu₂₀Fe₁₅, Al₆₅Cu₂₀Co₁₅ and Al₇₂Pd19.5Mn8.5 alloys during high energy ball milling and on subsequent annealing has been studied. The synthesis and stability of the quasicrystalline phase prepared by mechanical alloying of Al₆₅Cu₂₀Fe₁₅, Al₇₀Cu₂₀Fe₁₀ and Al₆₅Cu₂₀Co₁₅ alloys has also been studied. In all the cases, the quasicrystalline phase is unstable with long hours of milling and transforms to the β-phase (bcc phase), which is stable on further milling and on subsequent annealing up to 1073 K. The quasicrystalline to β-phase transformation appears to occur for grain sizes below 20 nm.