Cooling Rate Correlation between Microstructural Phases and Part Dimensions for EBM-Fabricated Parts

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This award supports fundamental research on the electron beam melting process, an additive manufacturing technology that builds three-dimensional shapes out of powder metals. The layer-by-layer fabrication process promotes distinct microstructural features dependent on cooling rates that are affected by part dimensions, among other factors. Mesh and foam cellular structures are a particular benefit of additive manufacturing and can be used to improve or increase the strength-to-weight ratio of production parts in the aerospace and other industries. Previously, these mesh and foam cellular structures fabricated by electron beam melting using a titanium alloy contained a titanium martensitic brittle phase that, hypothesized in this research, can be avoided by controlling the cooling rates during fabrication. Cooling rates will be measured with a multi-wavelength pyrometer to obtain point-specific, layer-by-layer part temperatures; and the smallest part dimensions that can be fabricated without compromising mechanical properties and microstructural architectures will be determined. Research results and dissemination of these results will provide recommendations and strategies to the broad additive manufacturing and metals fabrication communities to avoid the occurrence of brittle microstructures regardless of part dimensions. The lack of the titanium martensitic brittle phase will allow freedom in the design of parts containing mesh and foam cellular structures without compromising mechanical properties, which will provide an unprecedented benefit for using additive manufacturing technologies to directly fabricate next generation metallic components. The research will be performed at the University of Texas at El Paso, a minority serving institution with a Hispanic-majority student population, providing an unparalleled experience for the students involved in the program in the growing field of additive manufacturing.