Mossbauer effect studies of local Fe environments in crystalline and quasicrystalline Al-Cu-Fe alloys

Al-Cu-Fe alloys of several different stoichiometries have been prepared using a variety of sample preparation methods and have been studied using Fe-57 Mossbauer effect spectroscopy. Well ordered icosahedral, phason disordered icosahedral and rhombohedral crystalline phases were investigated. The resulting spectra indicate that the Fe environment in the various phases studied are virtually identical. However, as the sample stoichiometry is varied, two de-stabilizing mechanisms are observed for the icosahedral phase: one involving the formation of a pronounced correlation between the isomer shift and the quadrupole splitting; and the other associated with a reduction of the variance in the isomer shift distribution.