Design of Stable Nanocrystalline Alloys in Compound-Forming Systems
Technical Report,06 Aug 2014,05 Aug 2017
Massachusetts Institute of Technology (MIT) Cambridge United States
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The major goal of this project was to develop a set of guidelines for designing nanocrystalline alloys with structural stability that arises not due to a kinetic effect, which may be overcome with time, but due to a thermodynamic minimum in energy that is reliable. Specifically, the project sought to develop the alloy design principles for such thermodynamic stability for the entire periodic table of metals, including the alloy pairs that have negative heats of mixing and form compounds in equilibrium. These alloys are especially challenging to model in the nanostructured state, given that they can form more possible ground states that compete against a nanocrystalline state with grain boundary segregation. It was the specific goal of this project to expand our understanding of segregation-based stabilization of nanostructure to include such alloys. The specific task lines of the project formed subgoals on a path towards such detailed understanding. One task line was focused on the development of a set of computational tools for alloy design in nanostructured systems. These tools increased in sophistication as the project progressed, and have been used to propose new alloys with predicted nanostructure stability. In parallel, experiments in the PIs laboratory and with collaborators explored the alloys predicted by the computational program. These explorations validated and informed the models, and also led to materials processing strategies that have scalability and commercialization potential.
- Properties of Metals and Alloys