Heterogeneous nucleation interface between NbN(111) and TiN(111) in high-nitrogen austenitic stainless steels: First-principles calculation

Heterogeneous nucleation of NbN induced by TiN inclusions is important to play the role of precipitation strengthening in high-nitrogen austenitic stainless steels. In this work, the atomic structure, interfacial stability, and interfacial fracture toughness of TiN(111)/NbN(111) are investigated based on first-principles calculation. Furthermore, the interfacial bond structure and energy of TiN(111)/NbN(111) are also analyzed with and without Cr doping on the basis of Thermo-Calc phase diagrams. The results indicate that the lattice mismatch between the crystal face of TiN(111) and NbN(111) is lower than 5%, which reveals that TiN can act as the heterogeneous nucleus for NbN to grow. Besides, the maximum adhesion work at 4.58 J/m2 and the minimum interfacial energy at 1.28 J/m2 are presented on the stacking site of N-Ti TL, which suggests that (Ti, Nb) N phases can precipitate through this interfacial bonding mode. Moreover, from the view of bonding properties on the interface with and without Cr doping, it can be found Cr doping in two layers of the interface can enhance interface stability except for N-Ti TL (2Cr). This work will give promising guidance and theoretical basis for the controllable preparation of high-nitrogen austenitic stainless steels with in-situ precipitated nitride particles.