Refinement Mechanism Of (Ti, Nb)(C, N) Carbonitride In Hypereutectic Fe-Cr-C-Ti-Nb-N Coating By Ceo2: A First Principles Study

The interface relationship between (Ti, Nb)(C, N) carbonitride and CeO2 was calculated by first-principles method. The mechanism that CeO2 as the nucleus of (Ti, Nb)(C, N) carbonitride in Fe-Cr-C-Ti-Nb-N coating was analyzed. The microstructure of the hypereutectic Fe-Cr-C-Ti-Nb-N-CeO2 coating was observed in this paper. The calculated results show that, by calculating the phonon dispersion curves and binding energy, the most stable structure of (Ti, Nb)(C, N) carbonitride is Ti3NbCN3. The two-dimensional lattice misfit between Ti3NbCN3(111) and CeO2(100) is 6.47 %, which indicates that CeO2 as nucleus of Ti3NbCN3 is medium-effective. The four interface structures (O-TiNb, O-CN, Ce-TiNb and Ce-CN) were established between Ti3NbCN3(111) plane and CeO2(100) plane, in which, the interface adhesive work of the O-TiNb interface is the largest, which is 7.66 J/m(2), and its interfacial energy is the smallest, which is -0.82 J/m(2). It indicates that this interface is stable from a thermodynamic point of view. The bond of the O-TiNb interface is mainly covalent. Therefore, CeO2 can be effective heterogeneous nucleus to refine Ti3NbCN3. The experimental results show that, the coarse primary M7C3 carbides are distributed on the matrix of hypereutectic Fe-Cr-C coating. By adding Ti, Nb, N elements and CeO2 to the coaing, CeO2 can be used as heterogeneous nucleus to refine Ti3NbCN3, and thus further refine the primary M7C3 carbides.