Influence of Surface Preparation on the Formation of Surface Pits by Dezincification of Al–11%Zn Alloys

Abstract

The influence of surface preparation on the formation of surface pits in Al–11%Zn alloys during sublimation in vacuum has been reported. It has been shown that on electrolytically polished surfaces, the formation of a small number of pits results from the preferential sublimation of zinc from certain sites (sublimation pits), on which is superposed the general sublimation. In the case of electrolytically polished and thermally oxidized surfaces, identical sublimation treatments result in the formation of a large number of pits, the origin of which has been ascribed to the vacancy condensation at the metal/oxide interface as a result of the vacancies left by zinc-atom removal during sublimation (vacancy-condensation sublimation pits).