Role of Strontium on Sensitization and Unusual Passivation Behavior of a 5xxx Series Aluminum Alloy Containing a Trace Amount of Chromium

This paper reports the beneficial effects of strontium (Sr) on the sensitization kinetics and an unusually high passivation behavior in Al-5.7 wt% Mg alloy. The presence of strontium has aided not only in retarding the sensitization kinetics of Al-5.7 wt% Mg alloy but also significantly enhanced the intergranular corrosion resistance. The surface enrichment of Cr and Sr as oxides and hydroxides has caused an unusual increase in the passivity and pitting potential of Al-5.7 wt% Mg alloy. The presence of both Cr and Sr helped in retaining the passivity of the alloy even in the sensitized condition.