The effect of Si on the quasicrystalline phase formation in (Al 65Cu20Fe15)100-xSix alloys by mechanical alloying has been investigated. The study indicates that mechanical alloying improves the quasicrystalline phase forming ability in comparison to rapid solidification processing by widening the range of e/a ratio over which the icosahedral phase can be obtained. This range can further be enhanced by the addition of Si. In addition, Si improves the thermal stability of the quasicrystalline phase. The quasicrystals observed in the present study are in the nanocrystalline state. No amorphization has been observed even up to 15 at.% Si. © 2004 Elsevier B.V. All rights reserved.