DMREF/Collaborative Research: Designing and Synthesizing Nano-Metallic Materials with Superior Properties

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Often, the main factor limiting the performance of vehicles, power generators, civil engineering structures, and many other products is the durability of the metals they are made of. Better metals are therefore key to advancing technologies at the core of US competitiveness and security: transportation, energy, and infrastructure. Nano-metallic materials comprise a class of metals that promise to fill this need: they possess extreme strength, resistance to damage from repeated loading, and numerous unique properties such as resistance to radiation damage. This research project addresses a drawback of nano-metallic materials that has so far limited their practical use. Namely: when they stretch, they do not elongate uniformly throughout, but rather pinch off in isolated locations. This project will create nano-metallic materials that stretch uniformly and are therefore not prone to sudden failures. It will thereby remove a major impediment to the widespread technical use of nano-metallic materials and accelerate their deployment to the marketplace. This project will also undertake outreach activities to high school teachers and students, women, individuals from underrepresented minorities, and the broader scientific community. Even though many nano-metallic materials are intrinsically ductile, they appear to fail in a brittle-like manner because plastic deformation in them localizes into narrow zones that subsequently fracture. The goal of this project is to create nano-metallic materials that resist flow localization by engineering their architectures, interfaces/surfaces, and compositions via an iterative design process that integrates theory, modeling, and experiments. The project will follow an iterative design-synthesize-test cycle that scans the design space rapidly and integrates insights gained in each iteration by updating theoretical models connecting design parameters to performance metrics. Due to the nanometer-scale microstructure dimensions in nano-metallic materials, conventional dislocation-based mechanisms for averting flow localization are not applicable. Therefore, this project will explore and implement non-dislocation mechanisms that rely on twinning, surface and interface stresses, coherency stresses, interface barriers to slip, confined layer slip, and composites of flow-localizing and uniformly deforming constituents.