COMPORTAMENTO DA OXIDAÇÃO NA FASE ICOSAEDRAL DO QUASICRISTAL Al62, 2Cu25,3 Fe12,5.

Oxidation behavior of the quasicrystalline alloy with nominal composition Al62,2 Cu25,3 Fe12,5 was analyzed under different conditions of duration of thermal treatment. It was used X - Ray Diffratometry to follow the alloy phases evolution and Scanning Electron Microscopy (SEM) to analyze the quasicrystal morphology and oxidation. Below 750° C the alloy shows intermetallic phases with associations of the alloy elements and above 675° C the crystalline phase is stable. In icosahedral phase, aluminum oxidation forms a dense passivating layer at the outmost surface of the quasicrystal which causes depletion in both copper and iron. In the dense layer it was observed not only the presence of alumina, γ - Al2O3, but also the formation of hematite. [ABSTRACT FROM AUTHOR]