Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Dr. David Shoesmith

Abstract

This thesis reports a series of investigations into the influence of microstructure on the corrosion of Mg alloys. Mg alloys are prime candidates for the light-weighting of automobiles however any extensive applications are limited by their high corrosion rates. The corrosion resistance is further hindered by the susceptibility of Mg alloys to microgalvanic coupling occurring between the Mg matrix and the secondary microstructures in the alloys. This process and the individual contributions to it must be understood to improve Mg alloy design for automotive applications, develop methods for extending the lifetime of Mg alloys and developing models to successfully predict the corrosion behaviour of Mg alloys.

This thesis provides an essential contribution to the understanding of the microscaled corrosion of Mg alloys. The methodology developed can be further applied to a wide range of Mg alloys to investigate their behaviour. An ex-situ identifier of cathodic activity, a corrosion product dome, was confirmed; allowing for ease of identification of microgalvanic cathodes in future investigations. New approaches to controlling the corrosion rate of Mg alloys were also reported involving the application of small cathodic currents and introduction of ethylene glycol as the exposure medium

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