Comprehensive study of alloy catalysts and materials, AxByC1-x-y, is hampered by the fact that the study must span a multidimensional and continuous composition space, x = 0 ? 1 and y = 0 ? 1-x. Traditional methods of study can be circumvented by high throughput methods that use Composition Spread Alloy Films (CSAFs) as libraries of alloy composition. CSAFs are thin alloy films deposited onto substrates with gradients in their composition across the surface. As such they can contain all possible compositions of a ternary alloy, AxByC1-x-y with x = 0 ? 1 and y = 0 ? 1-x. Spatially resolved methods for characterizing the CSAF can then be used to determine bulk composition, surface composition, phase, electronic structure, etc. as functions of alloy composition, with arbitrarily high composition resolution. We demonstrate the utility of the CSAF methodology for study of alloy interface properties through a study of the surface oxidation of AlxFeyNi1-x-y alloys. The critical problem is to understand the role of Al in prevention of alloy oxidation by formation of a passivating layer of Al2O3 at the alloy surface. Using a AlxFeyNi1-x-y and a combination of energy dispersive x-ray spectroscopy, depth profiling using x-ray photoelectron spectroscopy, and Raman spectroscopy we have been able to map the Al concentration boundary in AlxFeyNi1-x-y above which the alloy is passivated. Along the AlNi binary, the passivation is caused by the formation of a surface layer of Al2O3. Along the AlFe binary, one can discern two regions of behavior, one in which the passivating layer is at the surface and the other in which the passivating layer is formed in the subsurface region beneath a layer of Fe2O3.

Oxidationproperties of AlxFeyNi1-x-ysurfaces across composition space

247th National Meeting (2014)

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