Formation of a stable decagonal quasicrystal in cobalt ion implanted aluminum

Abstract

A binary Al–Co decagonal quasicrystal has formed after 100 keV Co+-ion implantation into pure Al with a dose of 1.5×1017 ion/cm2, and the quasicrystal has shown a high thermal stability. The composition of stable decagonal quasicrystal is believed to be Al11Co4. Co+ ion implantation into Al first produced a multiple layer surface structure. The first layer was an amorphous layer. The second layer consisted of a decagonal quasicrystal and a coexisting amorphous phase. The amorphous phase in the implanted region where composition is close to Al11Co4 was transformed into the decagonal quasicrystal during annealing in a temperature range between 550 and 600 °C. Possible transformation mechanisms for the experimental results are discussed.