Oxidation and passivation of U(AlxSi1-x)3 alloy at elevated temperatures

Abstract The surface composition of U(AlxSi1-x)3 alloy (x = 0.57) and its interactions with oxygen, at elevated temperatures, were studied, utilizing Auger electron spectroscopy, X-Ray photoelectron spectroscopy and direct recoil spectrometry. Heating the alloy in ultra-high vacuum, results in aluminum (and some silicon) segregation to the surface, forming, above 700 K, a ∼0.6 nm self-assembly capping layer. Exposing the surface alloy to oxygen, at temperatures up to 500 K, causes oxidation of the uranium and the aluminum components, while silicon is only slightly oxidized. Above 600 K, only the aluminum segregated overlayer is oxidized, forming a passivation layer that inhibits further oxidation of the alloy.