Though an important point of study for miniaturized systems, deformation theory, and simulation, interactions between dislocations and boundaries, grain boundaries, particles, and material layers are still not very well understood. My research investigates the dislocation-interface interactions that are available to systems as a function of the strain they experience. The research involves fabricating micro electromechanical systems (MEMS) to take in-situ stress-strain measurements, transmission electron microscopy (TEM) for visualization and analysis of systems and defects, and tomography for three dimensional visualizations.
The following time resolved image sequence, courtesy of Dr. Y. Matsukawa illustrates how the bypass process varies as a function of strain. The same precipitate is being impacted by dislocations. The first sequence shows the bypass process early in the deformation. This appears to be a simple looping mechanism although no Orowan loop is produced. With increasing deformation, the bypass process changes - just compare the dislocation images in the two sequences to see the difference. The schematics suggest possible bypass mechanisms. The question is why does the mechanism change and what is the nature of the debris produced by the early stage reactions.
PhD Program in Materials Science and Engineering
BA in Physics, Knox College
BS in Materials Science, Fu Foundation at Columbia University
in-situ studies of dislocation-interface interactions