Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

From cars to integrated circuits, engineers locate different materials to best exploit their unique properties. It may seem odd then, that the production of structural alloys rarely employs this same optimized strategy. Despite the strong chemistry dependence of many material properties, alloys are typically designed by correlating properties to average chemistry. Recognizing this as an opportunity, our group is at the leading edge of a movement whose aim is to develop emerging processing techniques aided by advanced characterization and simulation tools to ‘put atoms where they are needed’ in engineering alloys. This is providing breakthroughs in new product development by, for example, using the natural tendency of strengthening atoms to migrate to ‘weak’ points in a material. Beyond the potential for new freedom in property design, such a chemically site-specific strategy offers a more efficient use of expensive and/or difficult to source alloying elements at a time where resource availability is an increasingly important consideration.
To achieve such site-specific chemistry and property control one can harness the natural tendency of chemical species to segregate to interfaces (internal or external) in metals. Applying this approach, recently coined ‘segregation engineering’, self-healing steels, improved conversion efficiency for low cost solar cells and photonic metallic nanostructures have been developed in the past 5 years.
A bottleneck for the development of future technologies via this route is our reliance on continuum models that are blind to the inherently atomistic structure of alloy interfaces. This lack of predictive sophistication slows development and risks missing novel solutions existing outside of current model calibrations. While current atomistic models are valuable for structure-property relationships in perfect crystals, none are well suited for alloy segregation where atomistic length-scales and diffusional timescales must be resolved for multicomponent chemistries.
This proposal seeks to fill the gap by deploying a new model, recently pioneered by our group, particularly designed for the prediction of segregation to alloy interfaces and defects. Integrating this model with an experimental program, we will map the segregation strengthening potential of alloying elements at interfaces and unravel the fundamental processes that control interfacial phase transitions and morphological instabilities. The ultimate goal is to deploy this strategy to revolutionize next generation high strength, lightweight structural alloys with surface driven functionality using the fundamentally guided interface structure-property relationships developed as part of this proposal.