Evolution of Metastable Phases During Mg Metal Corrosion: An In Situ Cryogenic X-ray Photoelectron Spectroscopy Study

Journal Article · Wed Dec 01 04:00:00 EST 2021 · Journal of Vacuum Science and Technology A--Vacuum, Surfaces and Films

DOI:https://doi.org/10.1116/6.0001305· OSTI ID:1829707

Shutthanandan, Vaithiyalingam ^[1]; Martinez, Abraham I. ^[1]; Varga, Tamas ^[1]; Devaraj, Arun ^[1]; Roy, Swadipta ^[2]; Stephens, Elizabeth V. ^[1]; Marina, Olga A. ^[1]; Thevuthasan, Suntharampillai ^[1]; Murugesan, Vijayakumar ^[1]; Joshi, Vineet V. ^[1]

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1. BATTELLE (PACIFIC NW LAB)
2. University of Texas at El Paso

Magnesium and its alloys are potential structural materials candidates for a wide variety of applications due to their high strength-to-weight ratio. However, ductility and poor corrosion resistance under ambient environmental conditions are the bottleneck for industrial deployment. Designing passivation layers and/or corrosion resistant alloys requires fundamental understanding of the corrosion process. The traditional ex-situ spectroscopic measurements of polycrystalline metal surface with ubiquitous surface impurities and grain boundaries only provided an 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 Mg single crystal surface exposed to aqueous salt solution. Clean Mg (0001) surfaces were exposed to pure D2O and NaCl aqueous solution (5 wt% NaCl+95 wt% D2O). The interfacial reactions were studied using multimodal analysis including XPS, x-ray diffraction (XRD) and scanning electron microscopy (SEM). In contrast to previous studies, our experiments demonstrated the formation of magnesium chloride hydroxide hydrate during aqueous salt corrosion processes. Evidence of metastable ClO* radicals were also found during the initial aqueous salt solution exposure.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1829707
• Report Number(s): PNNL-SA-164275
• Journal Information: Journal of Vacuum Science and Technology A--Vacuum, Surfaces and Films, Journal Name: Journal of Vacuum Science and Technology A--Vacuum, Surfaces and Films Journal Issue: 6 Vol. 39
• Country of Publication: United States
• Language: English