A discrete dislocation dynamics study of precipitate bypass mechanisms in nickel-based superalloys

Order strengthening in nickel-based superalloys is associated with the extra stress required for dislocations to bypass $\gamma'$ precipitates distributed $\gamma$ matrix. A rich variety of mechanism has been identified, various shearing and Orowan looping processes giving way climb as operating conditions change from low/intermediate temperatures high regime, temperature low regime. When anti phase boundary (APB) mechanisms operate, changes increased particle size within a broad coexistence window. Another possibility, supported by indirect experimental evidence, that third "hybrid" transition may operate. In this paper we use discrete dislocation dynamics (DDD) simulations study Ni-based superalloys. We develop new method compute generalized stacking fault forces DDD simulations. square lattice spherical $a/2\langle110\rangle\{111\}$ edge dislocations, function volume fraction size. show hybrid possible it operates between regimes over large range radii. also consider effects $\gamma/\gamma'$ misfit on mechanisms, which approximate an additional precipitate computed according Eshelby's inclusion theory. looping-shearing regimes, generally results stress. For sufficiently misfit, controlled pinning trailing exit side precipitates.