First-principles investigations of effects of solute elements on stability and electronic structure of laves phase/matrix interface in Ni-based superalloys

It is acknowledged that solute elements like Ru exert great influence on precipitation of deleterious topologically close-packed (TCP) phases. In this work, by means of first principle calculation based on density functional theory (DFT), the interface structure between C14-laves phase and matrix gamma phase has been established for the first time, and stable interfacial termination type was achieved. Effects of solute atoms like Ru on interface stability, electronic structure, and bond characteristics were further calculated. It has been proved that, unlike other elements, Ru can notably elevate the interfacial energy of C14-laves/gamma system, lower interface stability, and increase the difficulty of nucleation of C14-laves phase; on the contrary, W will decrease the interfacial energy of C14-laves/gamma and make it easier for C14-laves phase to nucleate; Re, Mo, and Cr will also increase the interfacial energy, but nowhere near the effect of Ru. Besides, in comparison with other solute elements, C14-laves/gamma substituted by Ru has the smallest degree of interfacial charge accumulation, lowest interfacial atomic bonding strength, and poorest interfacial stability. All the reasons discussed above lead to the blocking effect of Ru on the nucleation of C14-laves phase.