| Abstract Scope |
Defactancy is the use of chemical species, decorated on a defect, to lower the defect energy. In polycrystals, the defactancy of grain boundaries has been pursued for several decades as a means of stabilizing fine grain sizes, but the vast array of atomic environments in polycrystals makes the problem challenging to approach rigorously. This talk will review recent computational progress in achieving a rigorous approach to grain boundary segregation, and its application to defactancy. Treating the grain boundaries in polycrystals as a continuous spectrum of site types with unique thermodynamic properties, we are now able to target alloys that best offset defect energies. For binary alloys this leads to a limited number of options, whereas ternary or higher-order alloys exhibit far more flexibility for cooperative defactancy. At the finest grain sizes, the effects of triple junctions can also be considered, providing unique angles on the problem of structural stability. |