Icosahedral phase formation domain in Al-Cu-Fe system by mechanical alloying

Abstract

A systematic composition dependence study on icosahedral phase (i-phase) formation in the Al-Cu-Fe system has been carried out. Structural evolution during mechanical alloying and on subsequent heat treatment has been investigated by x-ray diffraction and transmission electron microscopy. The i-phase is observed to evolve from the reaction between the Al₂Cu and b phases. The influence of the Cu to Fe ratio (R_CuFe), Al to transition metal ratio (R_AlTM), and the electron to atom ratio (e/a) on the volume fraction of the i-phase has been studied. The analysis of the present results and those published earlier indicates that quasicrystal-forming ability correlates better with the RAlTM and e/a ratios. The volume fraction of the i-phase is maximum when the R_AlTM ^~2.3 and e/a ratio ^~2.0. Formation of the i-phase in Al⁶⁵Cu²⁵Fe¹⁰ by mechanical alloying is reported for the first time.