Effects of alloying elements X (Cr, Fe and Mo) on the interfacial properties of γ-Ni(110)/TiC(110) in TiC-particles reinforced NMCs: First-principles study

The interfacial structures of TiC(1 1 0)/γ-Ni(1 1 0) were established by means of first principles calculations, and the Case-IV interface among them was chosen as the most stable interfacial termination types based on the work of adhesion and interfacial energy. Effects of alloying elements X (Cr,Fe and Mo) on the Case-IV interface were analyzed from the aspects of segregation energy, interfacial stability, electronic properties, fracture mechanism and heterogeneous nucleation. The interfacial stability was researched by the work of adhesive and interfacial energy. The interfacial electronic structures and bonding characteristics were revealed by charge density difference and layer-projected DOS, respectively. The fracture mechanism was researched by carrying out first principles tensile test. The results show that Cr easily segregates at the Case-IV interface, while the segregation trend of Fe is weak and Mo is difficult to segregate at the interface. The interfacial stability is improved when Cr segregated at the Case-IV interface in the forms of Cr1, Cr2-1 and Cr2-2, but decreased by the introduction of Fe and Mo. The chemical bonds of the Case-IV interface consist of the Ni-Ti metallic bonds, Ti/Ni-C covalent bonds and Ni-C ionic bonds. The Cr-Ti metallic bonds and Cr-C polar covalent bonds with stronger bonding strength generated after the introduction of Cr contribute to stronger bonding characteristics and more stable interfacial structure in the Cr2-2 interface. The first principles tensile test shows that the doping of Cr atoms can strength the mechanical properties of the Case-IV interface. Therefore, Cr can effectively enhance the heterogeneous nucleation of γ-Ni matrix on TiC particles and improve the interfacial bonding strength in TiC-particles reinforced NMCs, while Fe and Mo play an opposite role.