EAGER: Bulk Nanostructured Metals from Twinned Nanowires

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Non-technical Abstract:Metals have widespread uses in electronics and infrastructure, and are the material foundation of modern civilization. A continuous piece of metal is made of densely packed, very fine grains. The size and structure of these grains, and the way they pack together determine the macroscopic properties of the bulk material. Typically, these grains are formed during the growth of the entire bulk material, and can be somewhat restructured during further processing. This project explores a contrasting approach, in which discrete metal nanocrystals are first chemically synthesized to yield well-defined structure, then assembled and densified to yield the final bulk nanostructured metal. This new approach allows for much higher degree of freedom to control the size, structure, and orientation of the metal grains, and can potentially create metal materials with novel properties. Technical Abstract:The new approach for creating bulk nanostructured metals departs fundamentally from the current ones, which are based on extensive plastic deformation of coarse-grained metal, atom-by-atom growth through electroplating or sputtering-based techniques, and consolidation of micron-size metal powders. In the new strategy, well-defined metal grains (i.e., nanowires) are first synthesized "atom-by-atom?" and then assembled to construct the final bulk metal "grain-by-grain". This can effectively decouple the tuning of grain microstructures and grain orientations, leading to new bulk nanostructured metals with previously unattainable microstructures (e.g., grain shape, orientation and nano-twinning) and novel properties. The project addresses a long missing connection between bulk nanostructured alloys (metallurgy-oriented) and colloidal nanomaterials (materials chemistry-oriented). If successful, it will inspire and catalyze a long overdue collaboration between these two independent areas of nanomaterials research. Students trained in the project represent a new breed of material scientists that can connect metallurgy with colloidal nanomaterials, bringing fresh mindsets to both areas.