Advanced Nano Manufacturing Enables Probing Fundamental Mechanical Behaviors of Materials

Citation

Zhang, Wenxin (2025) Advanced Nano Manufacturing Enables Probing Fundamental Mechanical Behaviors of Materials. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/fxq3-7817. https://resolver.caltech.edu/CaltechTHESIS:03132025-055626664

Abstract

The trend of miniaturization has revolutionized modern technologies, with micro- and nanoscale materials driving transformative advancements in high-tech industries and scientific discovery. Among the various properties and applications enabled at these small scales, nanomechanical properties play a fundamental role, underpinning the integrity and functionality of any structures or systems. However, despite advancements in both conventional and emerging micro- and nano-manufacturing strategies, there has remained a lack of direct “bottom-up” experimental pathways to fabricate and probe the mechanical responses of submicron-sized monolithic nano-specimens with unconventional microstructures and/or 3D nano-architectures with submicron-sized features, particularly for non-carbon materials.

In this work, I will present novel nano-fabrication and manufacturing strategies and their applications in addressing these nanomechanical challenges through three key studies. In Chapter 2, the deformation characteristic of organic ice is studied via cryogenic micro-compression and molecular dynamics simulations, providing insights into a benzene-ring re-orientation-mediated densification deformation route and offering new insights into planetary geology for celestial bodies such as Titan. In Chapter 3, we experimentally unveiled unprecedented two-regime size effects in additively manufactured metallic nanopillars with hierarchical microstructures, revealing a nanocrystallinity-, nanoporosity-mediated plasticity mechanism through atomistic insights. In Chapter 4, we extended this nano-manufacturing approach to explore nanoporosity-driven deformation behaviors in nano-architected metals with in situ experiments and finite element analysis. Together, these studies not only elucidate previously unprobed fundamental small-scale mechanical behaviors but also lay the groundwork for developing an advanced micro-to-nanoscale manufacturing platform, enabling complex systems and functional applications such as energy storage, biomedical microrobots, nanophotonics, and beyond, which I will briefly discuss in Chapter 5 as an outlook with a few examples from metal/oxide nanocomposites to interpenetrated pyrolytic carbon microarchitectures.

Thesis Files