Fatigue crack initiation
If you take 10 nominally identical samples and load each under fatigue until it fails, you’ll find that each sample can withstand a very different number of cycles, spanning orders of magnitude. This is due to tiny microstructural variations in the samples which can have a large influence on where and when cracks nucleate. We are using multiscale electron microscopy techniques, including EBSD analysis, in situ SEM and TEM deformation, and site specific analysis via FIB lift outs, to uncover the physics governing crack nucleation and growth under fatigue loading.
This work is supported by DOE BES
Material behavior in corrosive and embrittling environments
Materials used in application will almost always experience some form of corrosive influence, whether it be liquid metal coolants used in the next generation of nuclear reactors or simply the humidity in the air. We are developing in situ microscopy techniques to understand the relationship between microstructural features such as grain boundaries and dislocation configurations and the susceptibility to corrosive environments. Currently, we are investigating naval-relevant systems such as Al 5xxx in marine environments as well as model systems such as iron in acetic acid.
This work is supported by the Office of Naval Research