2, Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Nanocrystalline alloys can be designed to be stable by intentional grain boundary segregation: by using alloying elements that will segregate to the boundaries and lower the grain boundary energy, the driving force for grain growth can be attenuated or even eliminated. The main thermodynamic data necessary for predicting stability in nanocrystalline alloys is the segregation strength of the alloying element, quantified by the segregation energy. Segregation energy is usually calculated precisely only for specific high-symmetry boundaries that are not representative of the spectrum of states in a true polycrystal, or estimated in a semi-empirical manner for some “average” grain boundary assumed typical of a polycrystal. In this work, we outline the thermodynamic and computational framework to address equilibrium grain boundary segregation in full polycrystalline grain boundary networks, by developing a variety of atomistic tools. Specifically, we aim to understand the full spectrum of segregation energies, as well as the role of solute-solute interactions at the boundary. Our efforts to apply these methods across many alloy systems will also be addressed.