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Abstract

The dependence of high-temperature properties of Ni-based superalloys on the alloying additives is a subject of ongoing research. Current knowledge is mostly phenomenological in nature and the details of solute diffusion, interaction with defects such as interfaces, vacancies, and dislocations as well as the interplay between composition and microstructure are not well understood. In this work we investigate the solute-vacancy interactions and concentration/temperature-dependent diffusion behavior of selected alloying elements using a combination of density-functional theory calculations and kinetic Monte Carlo simulations.

Vacancy mobility is found to be only weakly influenced by solute presence, even for heavy refractory elements such as Re. Diffusion coefficients calculated by our approach are shown to be in good agreement with both experiment and simpler, but more limited, analytic models.