Effect of Fe substitution on the stabilization of the icosahedral phase in Al-Cu-V alloys

The effect of Fe substitution on the formation and stabilization of icosahedral phase in AI-Cu-V alloys has been investigated by employing transmission electron microscope and X-ray diffraction. In the as quenched Al75-xCu15-xFe5V5 alloys with x=0, 5 and 10 it has: been found that grain size of icosahedral phase increases from 156nm to 0.53 mum with increasing x. All the three alloys exhibit the formation of alpha -Al and 0-Al2Cu phases along with the i-phase. The nanoquasicrystalline and alpha -Al phases: in Al75Cu15Fe5V5 alloy transform to Al7Cu2Fe phase by annealing at 550 degreesC for 4 hrs by peritectic type of reaction. A curious type of pseudo-twelve fold electron diffraction pattern devoid of any diffuse scattering has been observed in some local regions of AI,,Cu,,Fe,V, alloy. The angles and details of twelve sectors are varying alternatively. A plausible explanation in terms of microtwin domains of 0-Al2Cu structure in [(1) over bar 10] orientation has been given to explain the characteristic features of the pseudo-twelve fold pattern.