  In film growth on quasicrystalline surfaces, the epitaxy-imposed ordering
cannot compete with the stable bulk phases of thick films due to absence of
translational order in the structure of the substrate. Energetically, this
renders the formation of crystalline domains in the native structure of the
film material more favorable while their global orientation is prescribed by
the quasicrystalline order. We present experimental results on the dissociative
chemisorption of oxygen on the decagonal surface of Al$_{70}$Co$_{15}$Ni$_{15}$
as well as molecular-dynamics simulations of the diffusion of adatoms on the
surface of the partially covered substrate.
