Mechanics of Materials at the Extreme Length-Scales

At the extremely small length-scales, the conventional mechanics of materials cease to be effective and new deformation mechanisms emerge. For example, dislocation based mechanisms in metals give way for grain boundary based mechanisms at the nanoscale. The focus of this research is on how mechanical breakdown at the extreme length-scales influence other physical properties. For example, grain boundaries impede current and heat carriers several orders of magnitude higher than dislocations do. As a result, when the mechanics change from dislocation (bulk) to grain boundary (nano) dominated one, very small change in strain can cause large changes in electrical or thermal conductivity. The core concept of this proposal is that at the extremely small length-scales, the mechanical deformation mechanics is strongly coupled with other physical (thermal and electrical) properties. The research will provide fundamental insights in the mechanics of materials at the extremely small length-scales, which will allow ?tuning? of thermal or electrical properties with strain for enhanced energy transport or conversion efficiency. The objective of this proposal is to study the role of specimen size, microstructure and defects on the coupling between mechanical deformation and electrical/thermal transport at the nanoscale. The PI will nanofabricate novel experimental tools with less than 3mm x 3mm size footprint to measure mechanical stress, strain, thermal conductivity and electrical conductivity of nanoscale thin films. From the data, the PI will construct the strain-temperature-transport (thermal and electrical) map to validate the proposed coupling concept. Seeing the defects and deformation as they evolve while measuring the thermo-physical properties will herald a paradigm shift in materials characterization and reduce the gap between theory and experiments. The proposed research will potentially impact the mechanical reliability and thermal management issues in future micro-electronics, flexible electronics, opto-electronics and laser devices, to name a few.