Characterization of Oxides from Al–Mg–Zn Alloys with Heat Treatment, with Scanning Electron Microscopy and Fluorescence Microscopy

Abstract

Al–Mg–Zn alloys have some electrochemical properties that benefit their use to be considered as sacrificial anodes. However, its efficiencies are inadequate to the commercial values so it is necessary to apply heat treatments to them. This paper evaluates the electrochemical properties of two experimental alloys: 9.4 Mg–7.4 Zn–Al and 7.9 Mg–13.3 Zn–Al, it also characterizes the corrosion products obtained from them using SEM and FM in order to evaluate their possible impact to the environment and their use as sacrificial anodes. The heat treatment lasting between 5 and 24 h presented the best corrosion velocities and current drainage capacity, showing in both cases localized corrosion in phases τ-Al₂Mg₃Zn₃ and Mg₂Si.