Nanomechanics of Tough Nanostructured Metals

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Nanostructured metals, with microstructural length scales typically smaller than 100 nm, have been the subject of considerable research in recent years. They are structurally characterized by a large number of internal interfaces such as grain boundaries or twin boundaries, which may significantly change their physical, mechanical, and chemical properties compared to the coarse-grained counterparts. In typical nanostructured metals, there is often a regrettable trade-off between strength and ductility. Nanocrystalline metals routinely exhibit up to five times higher strength than conventional coarse-grain metals. But their ductilities are often poor, thus limiting their structural and even functional applications. The goal of the proposed research is to develop a robust modeling and experimental framework for the design of tough nanostructured materials of ultrahigh strength and high ductility. Taking the nanostructured copper as a model system, a tightly coupled modeling and experimental study will be performed to elucidate the active mechanisms controlling ductility in nanostructured metals, and to develop novel processing methods for producing tough nanostructured materials. This research will achieve a broader impact through a fundamental advancement in the understanding of information mechanisms in nanostructured metals. The proposed research is the necessary first step toward engineering tough nanostructured materials which may lead to significant weight and energy savings in applications of microsystems. The knowledge of novel deformation mechanisms and processing techniques of nanostructured materials will be integrated into the senior undergraduate course. Minority undergraduates will be recruited for summer research on this project. We offer these opportunities to inspire their interests in pursuing the career in the area of nanoscience and nanotechnology.