****Technical Abstract**** This project supports development of a new, iterative alloy design methodology for bulk metallic glass (BMG) alloys that advances the objectives of the Materials Genome Initiative (MGI). This development requires a comprehensive approach, treating dynamics in the liquid, which are essential to the glass transition, and crystallization, which must be avoided to form a glass, on an equal footing, connected by the structure of the liquid and the glass. Achieving this goal requires the integration of experiments and simulations with tight feedback. The experiments include novel high-thermal-rate, high-throughput flash DSC to measure entire time-temperature-transformation curves and liquid fragility, and fluctuation electron microscopy (FEM) to measure new, otherwise inaccessible information about nanoscale structural order. Simulations include accelerated molecular dynamics to connect structure to liquid dynamics and crystallization along with the development and release of a new reverse structure determination software tool incorporating FEM data and ab initio Hamiltonians using genetic optimization and Bayesian statistics. The new methodology will be applied to develop new, bulkier Al-based metallic glasses, starting from the Al-Sm and Al-La systems, stabilized by minor alloying. A larger goal is to uncover fundamental new connections between composition, structure, atom dynamics, and crystallization; these will be used to create general, intuitive, cluster design rules to develop new BMGs.
Bulk metallic glasses (BMGs) are alloys that can be cooled from the liquid without crystallization, resulting in a glassy, amorphous solid. Sufficiently stable BMGs can be processed like plastics if the temperature is held in the supercooled liquid region, resulting in net-shape, seamless forming of complicated shapes by blow molding and rapid fabrication of nanostructures across large areas by hard-mask imprinting. New applications include packaging, arterial stents, water purification, and miniature gears and springs. This project will develop a new methodology for discovering new BMG alloys using an iterative strategy of state-of-the-art experimental and computational tools that advances the objectives of the Materials Genome Initiative (MGI). The method requires the integration of experiments and simulations with tight feedback between the four investigators with complimentary expertise to provide new scientific insights. The novel integrated computational and experimental approach, combining structure up to the nanometer scale and the kinetics of both glass formation and crystallization, may be transformative in yielding a unique combination of tools and approaches that may lead to a general method to design new BMGs alloys for a variety of applications. This project supports the education of students and post-docs in combined experimental and computational materials research in a collaborative environment, and development of outreach materials and demonstrations for younger students and the general public. This award is funded by the Division of Materials Research (DMR) and the Division of Mathematical Sciences (DMS).
