Dislocation core structures in Ni-based superalloys computed using a density functional theory based flexible boundary condition approach

Nickel-based superalloys are widely used in applications requiring high strength and creep and fatigue resistance at elevated temperatures. Such structural properties are controlled by the glide and cross-slip of screw dislocations in the Ni matrix and Ni3Al precipitates. The strengthening mechanisms are determined in turn by screw dislocation core structures that are difficult to image with weak-beam transmission electron microscopy. Core structures of two primary superalloy deformation modes, 1/2(110)Ni screw and (110) Ni3Al screw superdislocation, are predicted using density functional theory with flexible boundary conditions.