Molecular Dynamics Simulation of Dislocation-γ-Precipitate Interactions in γ’-Precipitates

There are clear experimental evidences of the formation of either spherical or platelet γ-precipitates inside cubic γ’-precipitates in nickel-based superalloys, which strengthen the mechanical property of the alloy. In this work, molecular statics (MS) and dynamics (MD) simulations of the interaction between a super edge dislocation and a γ-precipitate in γ’-precipitates were performed. The strengthening mechanism was then investigated by comparing the simulation results with the theoretical prediction. As the result, it could be found that the critical resolved shear stress (CRSS) of the interaction has a strong dependence on the shape of the γ-precipitate, and could be well predicted by the theory of precipitation strengthening. Especially, the stacking-fault, chemical, coherency and interface strengthening play a major role in determining the CRSS. Finally, the interaction under a finite temperature was simulated using the MD simulations. It was found that the influence of temperature on the interaction is negligibly small.