New Insights into the Adsorption of Fe on Ti(CxN1−x) Surface: First-principles Study

The present study systematically investigates the adsorption behavior of Fe atoms on the titanium carbonitride (Ti(CxN1−x)) surface during the initial stage of austenite nucleation. The results indicate that the formation energy of TiN is lower than that of TiC, suggesting that TiN is more likely to form. However, it is observed that the TiN content in the steel is so little. The C-Top site of TiC exhibits the highest adsorption capacity for Fe atoms. For the various stacking models evaluated for Ti(CxN1−x), the CNNC model exhibits the most favorable adsorption performance for Fe atoms in Ti(C0.5N0.5). Furthermore, TiC exhibits superior adsorption performance as compared to TiN, which is attributed to its shorter bond length and higher electron orbital overlap. When the Fe atoms adsorb on the TiC(001) surface, covalent bonds are formed among C, Ti, and Fe atoms, revealing the presence of metal bonds.