A computational method was described for the study of γ-precipitate strengthening of nickel-based superalloys, and for investigating the relative importance of stacking-fault energy and coherency strains. The method was a combination of parametric dislocation dynamics, an analytical solution to the spherical inclusion problem and the generalized Peierls–Nabarro model. Earlier analytical solutions to stacking-fault strengthening predicted a lower critical resolved shear stress in comparison with the results of the present model. This was attributed to shape changes of super-dislocations during their interaction with γ-precipitates. However, existing analytical solutions to coherency strengthening provide considerably larger values of the critical resolved shear stress compared with the results of present simulations. The dislocation core was found to spread widely as it interacts with γ-precipitates, and was thus much softer than what was considered in previous analytical solutions. This remarkable effect was a direct result of the core structure of dislocations interacting with precipitates. When this effect was accounted for, a new analytical solution was shown to give excellent agreement with present simulation results. The combined effects of the two strengthening mechanisms, when they operated simultaneously, were considered.

γ-Precipitate Strengthening in Nickel-Based Superalloys. A.Takahashi, M.Kawanabe, N.M.Ghoniem: Philosophical Magazine, 2010, 90[27-28], 3767-86