Ab-initio study of Re and Ru effect on stability of TCP nanoparticles in Ni-based superalloys

Modern nickel-based superalloys contain high concentrations of rhenium that allows the improvement of their creep strength. The high levels of rhenium, however, results in the formation of topologically close-packed phases (TCP) which have a negative influence on its properties. The addition of ruthenium was found to reduce the precipitation of nano-sized TCP phases, but the reasons have not been established. In this paper, by using an ab-initio approach, we studied the effect of rhenium and ruthenium on the structural properties of Ni matrix as well as the TCP phases. We demonstrate that Cr, Mo and W are the most effective additions to provoke the formation of TCP phases, whereas ruthenium has a destabilizing effect.