Microstructure and MicroScale Performance of Light Alloys

School of Materials

University of Manchester

Chemical and electrochemical processes proceed on the light alloy surfaces exposed to the environment or subjected to treatments commonly used for aerospace, automotive, construction and electronic applications. The result of alloy exposure or treatment can be corrosion, usually localised corrosion. For example, aerospace alloys, predominantly aluminium- and magnesium-based, suffer from various forms of localised degradation upon exposure to service conditions that limit their performance; in the transport industry, although local degradation does not impact upon structural integrity of the vehicles, it can produce unsightly blemishes and surface defects in form of filiform corrosion. The localised activity of the light alloys is frequently associated with alloy microstructure, since it provides regions of microstructural and therefore electrochemical differences. Control of localised electrochemical activity on the alloy surface can be achieved through modification of alloy microstructure, namely the distribution and composition of second phase particles, alloy texture and deformation.

This project, which is part of a collaborative programme with CSIRO in Australia, will focus on developing an understanding of the local electrochemistry on the surface of light alloys of different compositions and key aspects of their thermomechanical processing and joining that result in modification of the alloy microstructure. From the previous, a clear understanding of the key degradation mechanisms will be available that can be used in process control and hence, contribute to improved performance. The research will use a combination of relatively novel local electrochemical methods combined with high resolution analytical microscopy.