Collaborative Research: Tailoring the Stability and Deformation of Nanocrystalline Alloys through Hierarchical Engineering

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NON-TECHNICAL DESCRIPTION: Nanocrystalline metals are rapidly becoming regarded as a new class of engineering materials with advantageous mechanical properties, such as high strength and increased wear resistance. Despite the tremendous potential of these materials, structural instabilities and limited ductility continue to hinder their best technological utility. This research combines computational and experimental materials science to investigate a novel approach for improving the stability and mechanical behavior of nanocrystalline metals by introducing periodic non-crystalline regions into the crystalline matrix material. By understanding the stability and mechanical nature of these alloys, this activity assists in the development of a new generation of novel structural materials with tunable properties. The outlined framework also develops collaborative environments for seemingly disparate scientific disciplines and stimulates new research areas in the field of modern metallurgy. The addition of new educational modules into undergraduate engineering laboratory courses is infusing principles of integrated computational materials engineering into the existing engineering curricula at both Stony Brook and Drexel University. High school students are engaging in the research through cooperative research projects, which requires focused computational and experimental components, and presentation of the results at Interactive Research or "IResearch" workshops to undergraduates enrolled in the engineering laboratories. These endeavors are enriching research opportunities for students at the high school and collegiate levels, promoting student retention in STEM disciplines, and demonstrating how engineering research can positively impact society.TECHNICAL DESCRIPTION: The objective of this research is to develop a new fundamental understanding of the interplay between nanoscale grain boundary physics and interfaces at larger structural length scales, which are generated by introducing periodic amorphous regions into the monolithic nanocrystalline structure. This project combines massively-parallel atomistic simulations with the design, synthesis, and mechanical testing of nanostructured alloys composed of solute-stabilized nanoscale grain boundaries and periodically distributed amorphous layers. The research is examining how such composite structures influence stability of the nanocrystalline grain boundary network and augment the rate limiting deformation physics for enhancing ductility. Students are being trained in cutting-edge in situ characterization methods, nanomechanical testing, and computational modeling to establish correlations between microstructural variables and their thermal stability, deformation mechanism distributions, and measured mechanical properties. By developing such correlations, this research is advancing the fundamental understanding of new material architectures for enhancing ductility in nanocrystalline metals with the potential to transform current perspectives on the design of stable alloy nanostructures.