In my project, I focus on the influence of defects and interfaces on the structural stability in Ni-based superalloys and model the electronic structure by utilizing atomistic simulation methods. This includes high-throughput and large-scale simulations employing ab-initio methods, analytic bond-order potentials, and molecular dynamics. As a part of project C1 of SFB / TR 103 I investigate the effect of refractory elements on extended defects on extended defects in Ni-based superalloys.