Enhanced corrosion resistance of hypo-eutectic Al–1Mg–xSi alloys against molten sodium attack in high temperature sodium sulfur batteries

Abstract

Corrosion characteristics of hypo-eutectic Al–1Mg–xSi alloys, which can be used as insert metals of thermal compression bonding (TCB) joints in sodium sulfur cells, have been studied to enhance the corrosion resistance of the alloys in molten sodium at the cell operation temperature of 325°C. The results showed that the major corrosion product was a NaAlSi compound, and corrosion kinetics decreased as silicon concentration decreased without compromising the bonding strength. The parabolic rate constant of Al–1Mg–3Si alloys was smaller by 25.5% than that of Al–1Mg–12Si alloys.