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Understanding the influenceof interfaces like grain and interphaseboundaries on crystalline strength andmechanical properties is of paramount importance as they often serve as obstacles for dislocation motion, as well as dislocation sources and sinks. In conventional polycrystalline metals, for example, grain boundaries (GB) obscure the passage of the gliding dislocations, causing them to pile up against the boundaries,1 which leads to strengthening via a well-known Hall-Petch mechanism.2,3 These GB-dislocations interactions result in the scaling law, where the yield strength is inversely proportional to the square root of the grain size.2,3 However, when the grain size falls below ∼30 nm (nanocrystalline metals), the role of GBs shifts toward dislocation nucleation and absorption sites,4,5 and sometimes to the deformation path itself, such as GB sliding6-8 and Coble creep.9-11 This transition is manifested by a different scaling law, often referred to as “inverse Hall-Petch relation,”where the yield strength becomes lower wit