Nanoscale Mechanics of Bulk Amorphous Metals

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Abstract for ?Nanoscale Mechanics of Bulk Amorphous Metals?P. M. Voyles and D. S. StoneThe goal of this project is to understand structure-property relationships in bulk amorphous metals. Broadband nanoindentation creep will be used to measure plastic deformation of selected alloys under constrained conditions which suppress failure at low strain. The activation volume and activation energy of plastic deformation will be derived from creep data covering 5-6 orders of magnitude in strain rate. Fluctuation microscopy, which is based on spatial fluctuations in electron nanodiffraction, will be used to measure the nanometer-scale structure in the same alloys. Comparing the creep data and structure data should reveal how structure controls deformation, perhaps through controlling the size, critical strain, and density of shear transformation zones.Bulk amorphous metals are a new class of metal alloys. Their exceptional properties, such as hardness greater than conventional steels, but at lower density, high tensile strength, high yield strength, high elastic limit, and excellent corrosion resistance, point to exciting applications as structural materials or in biomedical implants and tools. Those applications will benefit if plastic deformation can be understood and eventually controlled at atomic and nanometer length scales, which is one of the long-term goals of this project. This project will also promote engineering education by involving undergraduates from groups historically underrepresented in engineering in forefront engineering research, and by disseminating methods and examples in forefront electron microscopy characterization of materials via a publicly accessible web database.