Effects of TiC addition on the interface stability, microstructure, and mechanical properties of IN718 fabricated by laser direct metal deposition: A combined experimental, DFT and MD study

Abstract

In this study, we reveal the impact of the addition of TiC in the IN718 superalloys at both atomic and micron scales through density functional theory (DFT), molecular dynamics (MD), and experimental analysis. From the micro scales, the addition of TiC can effectively mitigate the segregation behavior of Nb and Mo atoms, promote heterogeneous nucleation, reduce grain size, and thus improve mechanical properties. From the atomic scales, the effect of alloying elements (Fe, Cr, Mo, Nb, Co) on the stability of the TiC/γ-Ni interface was investigated through first principles. Co-doping interface was more stable than other interfaces by MD calculations, followed by Cr and Fe-doping models. The heat of segregation results inferred that TiC can effectively mitigate the segregation behavior of Nb and Mo atoms in the TiC/γ-Ni interface, it is mutually verified with the experimental results. Furthermore, the interface energy values theoretically illustrated that TiC particles could promote the heterogeneous nucleation of γ-Ni, this behavior of TiC particles was verified by experiment results. This investigation results provide reference information in the study of ceramic particle reinforced alloys at atomic and micron scales.