Atomic Scale Simulation of Defects in Bulk Materials and Monolayer Surfaces

Abstract

When engineering alloys come into contact with an environment a corrosion reaction will occur at the interface and reaction products form. The stabilities of such products are key to the corrosion performance of the alloy. A detailed understanding of how corrosion products behave at the atomic level would be of great significance for the development and optimisation of alloy compositions.

In this thesis atomic scale simulation techniques have been used to model the incorporation of foreign elements in corrosion products and the impact on transport properties. Two systems are studied: NiF₂ which is formed on nickel alloys in fluorine environments, and M₂O₃ corundum structures that form on aluminium and steel alloys in oxidising environments.

It is recognised that further simulation advances will be required before atomic defect simulation can be used to predict large volume and long time scale processes. As such, a simulation method is reported which offers advantages over traditional techniques and can predict atomic surface structure evolution over extended timescales. Here, model systems consisting of a gas monolayer on atomically rough metal surfaces are investigated; results are presented in analytical and graphical forms.

Full Text

• Preamble
• Motivation, Scope and Basic Principles
• Atomic Interactions
• Methodology Associated with Energy Minimisation
• Nickel Fluoride Passivation of Nickel
• Corundum Oxde Passivation of Aluminium and Steel
• Methodology Associated with Cellular Automata
• Simulation of Gas Monolayers on Rough Surfaces
• The c/a ratio in Rutile Structures
• Bibliography