Author ORCID Identifier
Year of Publication
Doctor of Philosophy (PhD)
Materials Science and Engineering
Dr. Matthew J. Beck
The applications of computational materials science are ever-increasing, connecting fields far beyond traditional subfields in materials science. This dissertation demonstrates the broad scope of multi-scale computational techniques by investigating multiple unrelated complex material systems, namely scandate thermionic cathodes and the metallic foam component of micrometeoroid and orbital debris (MMOD) shielding. Sc-containing "scandate" cathodes have been widely reported to exhibit superior properties compared to previous thermionic cathodes; however, knowledge of their precise operating mechanism remains elusive. Here, quantum mechanical calculations were utilized to map the phase space of stable, highly-faceted and chemically-complex W nanoparticles, accounting for both finite temperature and chemical environment. The precise processing conditions required to form the characteristic W nanoparticle observed experimentally were then distilled. Metallic foams, a central component of MMOD shielding, also represent a highly-complex materials system, albeit at a far higher length scale than W nanoparticles. The non-periodic, randomly-oriented constituent ligaments of metallic foams and similar materials create a significant variability in properties that is generally difficult to model. Rather than homogenizing the material such that its unique characteristic structural features are neglected, here, a stochastic modeling approach is applied that integrates complex geometric structure and utilizes continuum calculations to predict the resulting probabilistic distributions of elastic properties. Though different in many aspects, scandate cathodes and metallic foams are united by complexity that is impractical, even dangerous, to ignore and well-suited to exploration with multi-scale computational methods.
Digital Object Identifier (DOI)
Defense Advanced Research Projects Agency (DARPA) Innovative Vacuum Electronics Science and Technology (INVEST) program, under grant number N66001-16-1-4041 from 2018-2022.
National Aeronautics and Space Administration (NASA) Space Technology Graduate Research Opportunity, under grant number 80NSSC20K1196 from 2020-2022.
Seif, Mujan N., "Application of multi-scale computational techniques to complex materials systems" (2023). Theses and Dissertations--Chemical and Materials Engineering. 147.
Mechanics of Materials Commons, Metallurgy Commons, Nanoscience and Nanotechnology Commons, Other Materials Science and Engineering Commons, Structural Materials Commons, Structures and Materials Commons