Synthesis of quasicrystalline phase during mechanical alloying of Al₇₀Cu₂₀Fe₁₀

Abstract

An icosahedral phase (i-phase) has been synthesized by mechanical alloying of an elemental blend of Al₇₀Cu₂₀Fe₁₀. Mechanical alloying of Al and Fe in the stoichiometric ratio of 3:1 and continued milling after the addition of Al and Cu to yield the nominal composition of Al₇₀Cu₂₀Fe₁₀ does not result in the i-phase formation which requires subsequent annealing at 600°C for 4h for its formation. A single i-phase cannot be obtained even after annealing. In all cases, an Al(Cu, Fe) solid solution (β phase) has been found along with the i-phase. The i-phase appears to form by a peritectoid type of reaction between the β phase and Al₂Cu. The electrical resistivity of the nanocrystalline i-phase obtained in the present study was found to be about 2-3 orders higher than that found in thin films and it shows semiconducting behaviour.