Effect of Fe Substitution on the Stabilization of the Icosahedral Phase in Al-Cu-V alloys

Abstract

The effect of Fe substitution on the formation and stabilization of icosahedral phase in Al-Cu-V alloys has been investigated by employing transmission electron microscope and X-ray diffraction. In the as quenched Al75-x Cu15+x Fe5V5 alloys with x = 0, 5 and 10 it has been found that grain size of icosahedral phase increases from 156nm to 0.53μm with increasing x. All the three alloys exhibit the formation of α-Al and θ-Al2Cu phases along with the i-phase. The nanoquasicrystalline and α-Al phases in Al75Cu15Fe5V5 alloy transform to Al7Cu2Fe phase by annealing at 550°C 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 Al65Cu25Fe5V5 alloy. The angles and details of twelve sectors are varying alternatively. A plausible explanation in terms of microtwin domains of θ-Al2Cu structure in [10] orientation has been given to explain the characteristic features of the pseudo-twelve fold pattern.