| dc.description.abstract | Stainless steels are widely used in industry because of their excellent corrosion resistance. In the process of manufacturing stainless steels, a small amount of interstitial carbon (C) or nitrogen (N) is often added to enhance the corrosion resistance. Currently, our understanding of how these tiny elements affect the corrosion resistance is not comprehensive. Limited knowledge is achieved on the synergistic effects of interstitial C and N at the atomic scale on the corrosion resistance of stainless steels. However, this is crucial for designing stainless steels with high corrosion resistance for specific applications. Therefore, in this study, the density functional theory (DFT) calculation is applied to explore the influence of interstitial C and N atoms on the
corrosion resistance of stainless steels. Several analysis methods were utilized, including the bond-order bond energy (BOBE) model, density of states (DOS) analysis, crystal orbital Hamilton population (COHP) analysis, charge density difference and Bader charge analysis, to explore the synergistic effects of interstitial C and N. By decomposing the bond energy of metal-metal bonds, carbon-metal bonds, and nitrogen-metal bonds using the BOBE model, it is observed that both C and N exhibit local influences on the total energy of the alloy system. From the charge
density difference and Bader charge analysis, significant electron accumulation around C and N, and electrons transfer from the metal ions to C and N. Additionally, DOS analysis reveals an overlap of C and its first nearest neighboring metal atoms, which is also found in N and its first nearest neighboring metal atoms. However, no significant interaction was found between C and N, indicating local effects of interstitial atoms. Furthermore, the COHP analysis suggests covalent bonding features between N and first nearest neighboring metal atoms. Although the analysis indicates that C and N do not directly affect their electronic structure. In addition, charge density difference shows that when C and N are within the distance of the second nearest
interstitial position, a directionality of electron accumulation occurs. Electrons around C and N tend to accumulate between C and the shared metal atom, as well as between N and the shared metal atom. | en_US |