Dislocation assisted rafting in Nickel-based superalloys: a coupled phase-field / continuum dislocation dynamics modelWednesday (28.09.2016) 12:00 - 12:15 Part of:
Nickel-based superalloys play a major role in many technologically relevant high temperature applications. Understanding and predicting the evolution of the phase microstructure during high temperature creep together with the evolution of the dislocation microstructure is a challenge that up to date has not yet been fully accomplished.
Our two-dimensional coupled phase-field/continuum dislocation dynamics model explains microstructural mechanisms which are important during the early stage of rafting in a single crystal system. These simulations show that the long range shear stresses due to γ/γ' misfit and external loading drive dislocations towards the horizontal γ/γ' interfaces where microstructures consisting predominantly of geometrically necessary dislocations are formed. Such dislocation accumulations, in turn, change the elastic energy near the γ/γ' interfaces and result in γ/γ' precipitate rafting into horizontal direction. In this work, we study the influence of different dislocation densities on the rafted γ/γ' morphologies. We show how experimental creep strains can then be used to paramterize our simulations. Finally, we show first results from an extended simulation which additionally to dislocation glide also incorporates dislocation climb.