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Mechanical Behavior of Materials, and Defects in Solids

FWP Leader:Richard LeSar
Principal Investigators: S. Bulent Biner, Alan M. Russell, Kai-Ming Ho, Cai-Zhuang Wang

We propose an integrated experimental, modeling and simulation program to examine the underlying mechanisms of plasticity in nano- and micro-sized metallic samples. We will employ a new deposition method to create systems with well-controlled compositions and sizes ranging from about 100 nanometers to many microns.  By depositing the samples on photoresist-coated substrates, we can control system morphology and avoid contaminants or damage that can be caused by other, more intrusive, fabrication schemes. 

The mechanical testing of these samples will be carried out in a novel tensile strain gauge that enables accurate measurements of stress-strain behavior with concurrent in situ transmission electron microscopy (TEM) observations of evolving dislocation microstructures. Samples too large for in situ TEM will be examined with scanning electron microscopy (SEM), supplemented with TEM studies of sectioned samples. The experiments will be coupled with a modeling and simulation program that includes both atomistics and dislocation dynamics. The experiments will provide both realistic validation of models and a deeper understanding of fundamental dislocation mechanisms, enhancing the development of new theories of deformation. 

This program will not only shed new light on small-scale plasticity by bridging the current gap between the experiments and modeling, but it will also greatly enhance our overall understanding of many collective and cooperative mechanisms of plasticity in scales spanning from the nanoscale to the continuum.