Effect of Si addition on the formability of the icosahedral quasicrystalline phase in an Al₆₅Cu₂₀Fe₁₅ alloy

The effect of Si addition on the icosahedral forming Al₆₅Cu₂₀Fe₁₅ alloy was investigated. Conventional casting and melt spinning were employed with the addition of Si element. As Si was added up to 5 at.% replacing the Al atoms, the volume fraction of the i-phase gradually decreased. However, with increasing Si content further up to 15 at.%, an 1/1 cubic approximant phase formed instead of the i-phase. After heat treatment at 750 °C for 3 h, the volume fraction of the β-phase increased in an Al₆₄Cu₂₀Fe₁₅Si₁ alloy, while the volume fraction of the 1/1 approximant phase increased in an Al₅₀Cu₂₀Fe₁₅Si₁₅ alloy. The Al₅₀Cu₂₀Fe₁₅Si₁₅ alloy showed a relatively high hardness and fracture toughness compared to the other Si containing Al-Cu-Fe alloys.