The quasicrystalline transformation in the AlCr system

Amorphous Al₈₀Cr₂₀ films were made by coevaporation and by room temperature ion irradiation of the coevaporated films. The amorphous phase was transformed into the quasicrystalline state through two routes: thermal and ion beam assisted anneal. The intensity of the quasicrystalline electron diffraction pattern increases continuously within the annealing temperature range from 547°to 607°C. The starting state of the films (as-deposited or ion-irradiated codeposited) had no effect on the thermal transformation to the quasicrystalline state. Ion irradiation of the amorphous phase at 200°C produces a more complete set of icosahedral diffraction lines. Icosahedral AlCr has the same reciprocal lattice spacings as icosahedral AlMn.