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Joining of dissimilar metallic materials such as Inconel alloys and steel by vacuum brazing with copper (Cu) filler metal is highly desirable in a wide range of applications, for example, in construction of rotors for high-speed electrical motors. However, experiments have shown poor wettability of Cu on IN718 during vacuum brazing. In this work, molecular dynamics (MD) simulations are performed to study nanoscale interfacial phenomena that occur during brazing of IN600 and IN718 with steel using Cu. Hybrid potentials data is verified using density function theory (DFT) based energy calculation and melting point test models. The results show that IN600 coheres well with liquid Cu, whereas Niobium containing IN718 exhibits inhibited diffusion of atoms from the Inconel alloy into the liquid Cu. Additionally, the simulations show that liquid Cu atoms diffuse well into the precipitate (γ ′ ′ phase) in IN718 but barely diffuse into the parent γ phase. [Display omitted] • Molecular dynamics simulations of Copper's wettability on Inconel 718. • Niobium in Inconel restricts diffusion of alloying elements from the bulk. • Precipitates in Inconel impede spreading of copper on the interface. [ABSTRACT FROM AUTHOR]