Surface oxidation of a quasicrystalline Al-Cu-Fe alloy: No effect of surface orientation and grain boundaries on the final state

We have used x-ray photoelectron spectroscopy and Auger electron spectrosco py to examine the characteristics of oxides on two types of quasicrystallin e Al-Cu-Fe samples. One type was formed by consolidation of powders, result ing in multiple grains with random surface orientations. The other was a si ngle grain, oriented to expose a fivefold surface. Both were oxidized to sa turation in a variety of environments at room temperature. We measured the elemental constituents that oxidized, the extent of oxygen-induced Al segre gation, and the depth of the oxide. Under the conditions of our experiments , there was little, if any, significant difference between the two types of samples. Hence, surface orientation and bulk microstructure played little or no role on the final state of the oxide under these conditions.