Design and Evaluation of Hyper-Reactive Grain Boundaries in Nanothermites
Abstract
Approved for Public ReleaseReactive materials are thermodynamically metastable and undergo highly exothermic reactions upon appliedstress or heat. The reactive materials community made great progress in correlating ignition and combustion of reactive materials to bulk granular features (e.g., particle size distribution, particle morphology, grain size, void topology, etc.). However, mechanisms related to atomic-scale internal interfaces, such as internal heterophase boundaries, were relatively unexplored. Meanwhile, the solid-state interfaces community put forth a new paradigm of interfacial engineering that utilizes the phase-like behavior of interfaces to control bulk material properties such as atomic diffusion and thermal conductivity. The latest developments of interfacial engineering have not been applied to reactive materials. Therefore, the overarching goal of this hypothesis-driven research is tomerge these fields of study, while the underlying goals are to identify atomic mechanisms associated with subgranular features on reactivity, leverage interfacial transformations to optimize ignition and combustion of nanostructured reactive materials, and apply state-of-the-art atomic-resolution electron microscopy to directly observe interfacial reactions and extend the fundamental understanding internal microstructure-controlled reactive materials. Harnessing reactive interfacial transformations is a bold approach, but if successful, this research will lead to a high-level understanding of undiscovered atomic mechanisms that can be used to extendnovel materials-by-design strategies for next-generation energetic materials.The main research hypotheses are that (1) certain interfacial structures/chemistries are combustion rate-determining subgranular features, and (2) internal combustion of nanostructured reactive materials initiates by interfacial transformations, where heterophase interfaces absorb elemental segregants, transform, andignite/combust, eventually leading to thermal runaway. The objectives are to (i) develop a theoretical/computational toolbox that predicts interfacial transformations within inorganic reactive materials and suggests how to control interfaces, (ii) investigate howhigh-energy powder processing and low-temperature annealing treatments modify interfacial structures using advanced characterization techniques, and (iii) perform thermoanalytical measurements and ignition burn rate experiments to correlate interfacial phenomena to energetic properties. Al-based thermite model systems will be studied, where the objective is to deepen insights of these well-studied model systems with a more specific emphasis on discovering atomic-scale mechanisms. The outcomes of this research are expectedto help develop other material systems, such as new and novel materials for hypersonic applications, all critical to the overall DoD S&T mission.This work is supported by an Advisory Panel composed of academics (Dr. Michelle Pantoya), industrial partners (Dr. Pascal Dubé), and LSU research administrators (Greg Trahan). The Panel will cement PI Marvel in the reactive materials community, cultivate new collaborations, ensure longevity of his research contributions to ONR, and help transition the main research outcomes to the energetic materials community. Dr. Marvel is poised to contribute to the DoD S&T mission considering his strong history of performing DoD-sponsored research: his Ph.D. research focused on grain boundary complexions and funded by an ONR MURI; his postdoctoral research was supported in part by the 2020 MEDE-MSA fellowship with a focus on design of armor ceramics; and his research at LSU is funded by a multi-university $25M Cooperative Agreement with the DEVCOM ARL to develop new metallic alloys for potential use in hypersonic systems. The students supported by this work will be encouraged to submit DoD-sponsored fellowships.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 12, 2025
- Source ID
- N000142512192
Entities
People
- Christopher J. Marvel
Organizations
- Louisiana State University
- Office of Naval Research
- United States Navy