Al-Cu-Fe quasicrystals: Stability and microstructure

AlCuFe quasicrystal has been considered a novel icosahedral quasicrystal in as much as it can be produced ill both thermodynamically stable and metastable state, It is also recognised to be a face centred structure. The system has been studied extensively in the recent past and several contentious results have been obtained, For example, evidences have been presented for both reversible and irreversible transformation of the quasicrystalline phase to the crystalline phases, Similarly, distinct transition metal sites have been proposed based on the Mossbauer studies. A subsequent study of this in fact shows an absence of such distinct sites. It has been shown that in this system, vacancy type of defects of very large concentrations exist. Many of these factors-bring into question, the various structural models that have been postulated to explain the icosahedral structure obtained in the system. A critical examination of these various aspects of the AlCuFe quasicrystal is presented.