Advanced Nano Manufacturing Enables Probing Fundamental Mechanical Behaviors of Materials

Author: Zhang, Wenxin

Year: 2025

Degree: Dissertation (Ph.D.)

Advisor: Greer, Julia R.

Committee Members: Ravichandran, Guruswami; Pellegrino, Sergio; Faber, Katherine T.; Greer, Julia R.

Option: Mechanical Engineering

DOI: 10.7907/fxq3-7817

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.

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