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A comprehensive study utilizing first-principles calculations has examined the heterogeneous nucleation of TiN on Al2O3 in steel and the impact of alloying elements on this process. Additionally, the study delved into how this nucleation affects local corrosion activity. The findings indicate that alloying elements such as Cr, Mn, Mo, and V tend to concentrate at the Al2O3 (0001)/TiN (001) interface, enhancing the interface's stability, thereby favoring the heterogeneous nucleation of TiN on Al2O3. Consequently, the nucleation leads to the formation of interfaces, namely Al2O3 (0001)/TiN (001) and TiN (100)/bcc-Fe (100), which are less prone to adsorbing chloride ions, replacing the Al2O3(0001)/bcc-Fe (110) interface that can stably adsorb chloride ions, consequently reducing the adsorption of chloride ions at grain boundaries. Moreover, it is difficult for Cr atoms to incorporate into the TiN structure, while Ti atoms readily replace Cr in CrN. TiN exhibits a lower formation energy compared to CrN, and the precipitation of TiN mitigates the formation of Cr-depleted zones, thereby inhibiting local corrosion. |
