Solidification paths for an icosahedral quasicrystalline phase in cast Al62Cu25.5Fe12.5 and Al55Cu25.5Fe12.5Be7 alloys

The solidification behavior of the icosahedral (i) phase in (Al62−xBex)Cu25.5Fe12.5 (x=0,7) alloys has been investigated using a conventional casting technique. It was observed that the addition of beryllium (Be) modified the i-phase formation mechanism from peritectic reaction to primary solidification compared to as-cast Al62Cu25.5Fe12.5 alloy. The establishment of the new solidification path is attributed to the narrowing of the freezing range resulting from the beryllium addition. However, the resolidification at a slow cooling rate could result in the formation of the i-phase by peritectic reaction. The conversion of the initial solidification path to the peritectic solidification was attributed to a cooling rate effect resulting from the elaboration process. A new decomposition process of the bulk single i-phase in the Be-containing alloy is also proposed in the present paper.