| AVS 65th International Symposium & Exhibition | |
| Advanced Surface Engineering Division | Tuesday Sessions |
| Session SE-TuA |
| Session: | Wear, Oxidation and Corrosion Protective Coatings |
| Presenter: | Vaithiyalingam Shutthanandan, Pacific Northwest National Laboratory |
| Authors: | V. Shutthanandan, Pacific Northwest National Laboratory A. Martinez, Pacific Northwest National Laboratory P.V. Sushko, Pacific Northwest National Laboratory A. Devaraj, Pacific Northwest National Laboratory E. Stevens, Pacific Northwest National Laboratory O.A. Marina, Pacific Northwest National Laboratory V. Joshi, Pacific Northwest National Laboratory S. Thevuthasan, Pacific Northwest National Laboratory V. Murugesan, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Magnesium metal is potential candidate for high strength to weight ratio alloys with wide application in aerospace and automotive industries. However, poor corrosion resistance under ambient environmental conditions is the bottleneck for industrial deployment. Designing passivation layers and/or corrosion resistance alloys require fundamental understanding of the corrosion process. The traditional ex-situ spectroscopic measurements of polycrystalline metal surface with ubiquitous surface impurities provided indistinct view of the corrosion process. To clearly distinguish the mechanism and sequence of corrosion process, we employed in-situ cryo-based x-ray photoelectron spectroscopy (XPS) measurements on well-defined Mg-single crystal surfaces in combination with ab initio atomistic modelling studies. Mg (0001) surfaces were exposed to ambient water conditions (i.e. D2O and 5 wt% NaCl+95 wt% D2O solution) and the subsequent interfacial reactions were studies through integrated experimental and theoretical approach. This study provides atomistic view of Mg(OH)2 nucleation as main product of the corrosion process. Under salt conditions, the competitive nucleation process between Mg(OH)2 and MgCl2 were observed. High resolution helium ion microscopy images of the corroded surface show unique morphologies of nucleates including some well-defined faceted cubic crystals and micron size faceted ribbon like structures. By combining the energy requirements from computational modelling and the electronic states of corrosion products, the mechanism and sequence of corrosion process on Mg metal will be discussed.