This work will utilize meso-scale analysis techniques to study indentation driven nucleation of dislocations in perfect crystals. In particular, the linear mechanical response of mesoscale regions, intermediate between the atomic scale and full system size, will be probed in order to search for embryonic defects. Atomistic computer simulations will be performed using classical empirical potentials to study the process in a perfect thin-film under a smooth, nanometer-scale, indenter. Furthermore, the nucleation phenomenon will be studied within a continuum framework, field dislocation mechanics (FDM). Direct comparisons will be made with in-situ electron microscopy imaging during indentation of single-crystal Al. The ultimate goal is to construct a simple analytical framework which would be able to predict thermal activation barriers governing nucleation given a few simple material parameters and geometrical loading conditions as inputs.
The current state-of-the-art for predicting plastic deformation in ductile metals remains largely empirical and phenomenological. A "first principles," bottom-up, quantitative understanding of plasticity would allow for the design of materials with optimal mechanical properties such as increased strength and toughness. The work will also involve secondary education outreach co-ordinated through the Pittsburgh Supercomputing Center and targeted at under-represented populations in the urban core of Pittsburgh.
