This is a past event.

Unraveling the mechanisms of alloy oxidation with surface science studies

This seminar illustrates the integration of surface science studies and material synthesis as a powerful tool to create new materials, devices, and advance integration across materials platforms. We have studied the atomic scale mechanisms of alloy oxidation Ni-based superalloys, NiCr, and NiCr-W/Mo, which are coveted for their corrosion resistance. This work is positioned at the intersection between our desire to develop a deep mechanistic understanding, and the engineering challenge to integrate corrosion resistance as a design parameter. The focus for this presentation is on dry oxidation, and specifically the initial oxidation steps where the transformation from pristine alloy to oxide layer occurs, and ultimately connects to the much better studied Cabrera-Mott regime. The competition between different oxidation pathways is at the root of compositional, and electronic heterogeneity in the alloy, oxide and its interfaces. The competing reaction pathways are unraveled using a combination of scanning probe methods (STM/STS), and electron spectroscopy techniques in synchrotron based operando studies at Brookhaven National Laboratory, and most recently a time-resolved study using XPEEM, whose preliminary results will be shown. If time permits, I will show some work on aqueous corrosion specifically with respect to the reaction with chloride, and the role of crystallographic orientation on passivation.