AVS 62nd International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS-WeM

Paper SS-WeM11
Environmental Effects on Oxidative Surface Passivation Across AlxFeyNi1-x-y Composition Space

Wednesday, October 21, 2015, 11:20 am, Room 112

Session: Environmental Interfaces, Ambient Surfaces, In-Operando Studies and Adsorption on 2D Materials
Presenter: Matthew Payne, Carnegie Mellon University
Authors: M.A. Payne, Carnegie Mellon University
J.B. Miller, Carnegie Mellon University
A.J. Gellman, Carnegie Mellon University
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Alloys that derive robust oxidation resistance by the preferential formation of a passivating Al2O3 scale are commonly used for structural applications in thermochemically harsh operating environments. Often, one of the primary design concerns is to determine the lowest Al content required to induce passivation, so as to minimally impair the mechanical properties of the material. This “critical Al concentration” is kinetically dictated and can depend strongly on both multicomponent composition and the nature of the oxidizing environment. We have previously developed high-throughput methodology to study oxidation using composition spread alloy films (CSAFs), combinatorial sample platforms with continuous lateral composition gradients. Behavior related to oxidative corrosion and passivation can be characterized continuously across an entire ternary composition space with a single CSAF, using a combination of spatially resolved techniques including optical imaging, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoemission depth profiling. We have used this methodology to compare the oxidation of AlxFeyNi1-x-y alloys at 700 K in dry-air and humid-air environments. The critical Al concentration in the Fe-rich region of composition space was found to be significantly higher for exposure to the humid air. The continuous nature of the results provides valuable fundamental insight into the interplay of composition and environment on alloy oxidation kinetics.