Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 100: Metal Substrates: Adsorption and Reactivity
O 100.6: Talk
Friday, March 20, 2015, 11:45–12:00, MA 043
An ab initio study on the oxidation of Mg-Zn alloys and the MgZn2 intermetallic compound — •Su-Ting Cheng, Mira Todorova, and Jörg Neugebauer — Max-Panck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
A first step towards protecting iron from corrosion is galvanization, i.e. coating the iron surface with Zn. Recent experimental investigations have revealed [1], that addition of Mg can significantly improve the corrosion properties of Zn: the loss of weight during electrolysis of the intermetallic compound MgZn2 was reduced by 1/3 compared to results for pure Zn [2]. This seems astonishing in view of the high affinity of Mg to oxidise, which we relate to the appearance of attractive interactions arising between electronegative adsorbates on the Mg(0001) surface [3]. Using density functional theory calculations we investigate clean and oxygen covered Mg-Zn and MgZn2 surfaces and find the formation of a rather compact surface oxide. We will discuss our results in the context of corrosion protection.
[1] R. Hausbrand, M. Stratmann, and M. Rohwerder, Corrosion Science 51 2107 (2009)
[2] E. Diler, S. Rioual, B. Lescop, D. Thierry, and B. Rouvellou, Corrosion Science 65 178 (2012).
[3] S.-T. Cheng, M. Todorova, C. Freysoldt, and J. Neugebauer, Phys. Rev. Lett., 113, 136102 (2014).