Place: EuroSuperalloys, Oxford, UK
Ni is a base component in superalloys and Re is one of the key ingredients to improve mechanical properties in Ni-based alloys, especially creep resistance. It is, however, not fully understood how Re affects creep. Previous studies showed that within the dilute limit there is almost no effect of Re on the diffusivity of the atoms or the mobility of the vacancies. In this study, we extend our investigation to the non-dilute regime of Re by including Re-Re interactions. We use a kinetic Monte Carlo (KMC) approach to simulate diffusion in Ni-Re alloys and also investigate Ni-W and Ni-Ta alloys which are further important alloying elements in the Ni-based alloys. Key parameters in the KMC model are diffusion barriers, which strongly depend on the local atomic configuration. Using density-functional theory calculations we assess the composition dependence of the diffusion barriers and derive a model to explicitly include it in the KMC simulations. This allows us to study diffusion properties over the entire composition range and evaluate the vacancy mobility as a function of solute concentration.