Microstructural evolution of ion-beam-mixed Al-Fe multilayers for the formation of quasicrystalline or amorphous homogeneous alloys

Al and Fe multilayers thermally evaporated on sapphire substrates have been mixed by irradiation with 800-keV ${\mathrm{Xe}}^{+}$ ions at two different temperatures (liquid-nitrogen temperature and 493 K) and with fluences ranging from 2\ifmmode\times\else\texttimes\fi{}${10}^{15}$ to 3\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ions/${\mathrm{cm}}^{2}$. The structural evolution of the irradiated samples has been followed using complementary characterization techniques such as transmission electron microscopy and conversion-electron M\"ossbauer spectroscopy. Homogeneous amorphous or quasicrystalline phases are obtained at doses of 3\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ions/${\mathrm{cm}}^{2}$ at 77 K or 8\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ions/${\mathrm{cm}}^{2}$ at 493 K, respectively. Different evolutions with ion dose are observed in both cases involving combinations of various sites that tend to final states with dominant local environments characteristic of amorphous or quasicrystalline phases.