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Kinetic Monte Carlo  Modelling of Dissolution and  Passive Film Formation in  Fe-Cr Alloys

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posted on 12.11.2021, 11:43 by Parker, Amanda Jeanne

Stainless steels differ from iron in that chromium content allows for the formation of a passive iron-chromium oxide film which is only nanometres in thickness, offering protection from the environment. While the composition of this oxide layer has been established, the mechanism of its formation is not well understood. In particular, the threshold level of chromium for oxide formation is significantly lower then the chromium content of the alloy itself. We present a Cahn Hilliard type analytical model that relates the onset of passivation to an instability which leads to a phase segregating current above 17% Cr in a bulk alloy. Proposing that this current could lead to Cr enrichment at a surface, we compare atomistic simulations with and without a surface driven Cr current. We implemented a kinetic Monte Carlo algorithm with extensions to allow for vacancy assisted nearest neighbour migration in a body centered cubic alloy, tracking a surface, dissolution and surface passivation. We compare the time evolution of Fe dissolution rates, Cr surface enrichment and the threshold for passive film formation and find that the Cr current has a significant impact on each of these properties.


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Date of Award



Te Herenga Waka—Victoria University of Wellington

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Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level


Degree Name

Master of Science

Victoria University of Wellington Item Type

Awarded Research Masters Thesis



Victoria University of Wellington School

School of Chemical and Physical Sciences


Hendy, Shaun