|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||Modeling Alloying Effects on Hydrogen Evolution Reaction Kinetics for Decelerated Magnesium Corrosion
||Krista Limmer, Joseph Labukas, Jan Andzelm
|On-Site Speaker (Planned)
The corrosion behavior of magnesium has long been correlated with the hydrogen evolution reaction (HER) on the magnesium surface. Owing to the relatively slow anodic kinetics of pure magnesium, reducing the overall corrosion rate of magnesium requires a reduction in the HER kinetics. Alloying additions and impurities generally accelerate the cathodic kinetics through the formation of intermetallics, insoluble impurity islands, or the enrichment of noble elements on the magnesium surface. Alloying with arsenic has recently been observed experimentally to poison the cathodic kinetics of magnesium, although the mechanism of this reduction is uncertain. In this study the HER kinetic barriers for alloyed magnesium were evaluated using first principles density functional theory. The HER was examined on the basal (0001) surface of dilute binary Mg-X alloys following a recent atomistic mechanism model of hydrogen recombination and evolution. The adsorption energy of hydrogen atoms and the H2 molecule on the Mg-X surface was used as a method to rapidly survey more than 20 alloying additions as possible cathodic poisons. The full hydrogen recombination and evolution kinetic barriers were then examined in detail for selected alloying elements (e.g. As and Ge). This mechanistic understanding of how alloying additions contribute to the poisoning of magnesium corrosion may be used to develop magnesium alloy systems with reduced corrosion rates.
||Planned: Supplemental Proceedings volume