THE COMPARISON OF THE MICROSTRUCTURE AND CORROSION RESISTANCE OF SAND CAST ALUMINUM ALLOYS

The influence of different types of precipitation on the corrosion behavior was investigated in three aluminum-silicon-magnesium alloys. The microstructures of the alloys were studied through optical (OM) and scanning electron microscopy (SEM). The structures consisted of an alpha-Al solid solution matrix, Si eutectic crystals, secondary phases AlFeSi and AlMgFeSi (Chinese script), as well as Mg2Si. The corrosion behavior was examined with the use of a potentiodynamic polarization test followed by a SEM surface analysis. The results indicate that all the analyzed samples were in the passive state and AlSi10Mg was less reactive in the corrosive environment.