Extended phase-field model of Inconel 625 with more thermodynamically-consistent diffusion parameters while overhauling mathematical framework. Monitored, maintained, and upgraded shared computer hardware in the Center for Theoretical and Computational Materials Science; helped to address user concerns by building updated software versions and exploring filesystem upgrades to alleviate resource contention. Developed training materials through High Performance Computing Carpentry, created user-editable Wiki pages for CTCMS and Enki clusters, and documented major cluster features and common workflows for each.
Implemented phase-field model for solid-state transformation in alloy systems with three components and four phases, analogous to Inconel 625. Designed initial conditions based on electron micrographs of additively manufactured Inconel 625 to simulate microstructure evolution during heat treatment. Produced thermodynamic models through simplification of quantitative CALPHAD databases while retaining key phase diagram features, using computer algebra systems to accurately generate expressions and multivariable derivatives for import into phase-field software.
Part-time during master's degree. Researched non-toxic alternatives to CdS, reporting to senior management. Traveled to Helsinki to evaluate state-of-the-art atomic layer deposition reactor.
Researched alternatives to chemical bath deposition of CdS thin films, including nontoxic materials and novel reactor geometries. Achieved 72× scaleup in CdS deposition area with only 6× increase in waste generation.
Thesis: "Bias in Polycrystal Topology Caused by Grain Boundary Motion by Mean Curvature"
Performed large-scale phase field simulations of normal isotropic grain growth on high performance computing clusters including AMOS, an IBM Blue Gene/Q supercomputer. Designed and implemented algorithms to reconstruct polyhedral grain topology (faces, edges, and vertices) from diffuse interfaces in 2D and 3D phase field datasets. Found the process of triangular face elimination responsible for biasing topology in populations of polyhedral grains in synthetic, simulated, and real metal microstructures.
Thesis: "Effects of Magnesium(II) on Zinc Oxide Nanorod Growth From Aqueous Solution"
Designed experiments to deposit ZnO on glass substrates using a novel flow-through aqueous chemical reactor. Found minor effects of Mg2+ ions on ZnO film stress and lattice parameters.
D. Wheeler, T. Keller, S. DeWitt, A. Jokisaari, D. Schwen, J. Guyer, L. Aagesen, O. Heinonen, M. Tonks, P. Voorhees, and J. Warren. "PFHub: The Phase-Field Community Hub. " Journal of Open Research Software 7 (2019) 29. DOI: 10.5334/jors.276.
T. Keller, G. Lindwall, S. Ghosh, L. Ma, B. Lane, F. Zhang, U. Kattner, J. Heigel, E. Lass, Y. Idell, M. Williams, A. Allen, J. Guyer, and L. Levine. "Application of finite element, phase-field, and CALPHAD-based methods to additive manufacturing of Ni alloys. " Acta Materialia 139 (2017) 244—253. DOI: 10.1016/j.actamat.2017.05.003.
T. Keller, B. Cutler, E. Lazar, and D. Lewis. "Comparative grain topology. " Acta Materialia 66 (2014) 414—423. DOI: 10.1016/j.actamat.2013.11.039.
T. Keller, B. Cutler, M. Glicksman, and D. Lewis. "Enumeration of polyhedra for grain growth analysis. " In Proceedings of the First International Conference on 3D Materials Science (Seven Springs, PA: 2012) 97—106. DOI: 10.1007/978-3-319-48762-5_15.
"The group is recognized for leading a stakeholder community to establish benchmarks for evaluating and validating phase field simulation software useful to the design and manufacture of advanced materials. The group convened and led 10 workshops since 2015 to establish eight distinct benchmark challenges, and to determine stakeholder needs for a benchmark repository and database. The resulting digital infrastructure that the group built, PFHub, is used by scientists worldwide and is broadly recognized as the world’s authoritative resource for validating phase field simulation software and results."
"For exceptional contribution to the field of metal additive manufacturing with a focus on developing integrated simulation methods to predict microstructure evolution based on phase-field models, computational thermodynamics, and finite element analysis."
*Presenter's name is underlined.
*Presenter's name is underlined.