Directional coarsening of nickel based superalloys is modeled taking into account the role of anisotropic misfit relaxation by dislocations generated during creep. The directional coarsening is the response to the gradient in elastic energy induced by this anisotropic relaxation. A 3-dimensional computer simulation has been developed to describe both the morphologies and the kinetics of the phenomenon. Results of the simulation are presented and compared to experimental observations on an AMI superalloy. Morphology maps describing the expected rafting geometry for other superalloys, as a function of misfit and applied stress, are established and discussed.