Structural transformations at the surface of the decagonal quasicrystal Al70Co15Ni15

By using Auger electron spectroscopy and secondary-electron imaging, we sho w that, as a result of bombardment with 1.5-keV Ar+ ions, Al is preferentia lly sputtered and the surface structure of a decagonal Al70Co15Ni15 quasicr ystal transforms to body-centered cubic. Annealing the sample at 700 It res tores the Al concentration at the surface and, thereby, the quasicrystallin e structure. Real-time observations establish the orientational relationshi p between the quasicrystalline and cubic surface structures, which we use t o propose an atomic model of their interface. [S0163-1829(98)03246-9].