First-Principles Study On Structure Stability And Electronic Property Of Cr₂N And γ-Fe/Cr₂N Interface With Alloying Additives M（M=Mn, V, Ti, Mo, Ni）

High-nitrogen austenitic steels(HNAS) are widely used in many industrial sectors because of their greater corrosion resistance and mechanical properties when compared to those of the traditional stainless steels. Upon heating HNAS to high temperature for a suf?cient time, secondary phases chromium nitrides may precipitate, in particular between 700°C and 1000°C. Many investigators have reported that Cr segregated at grain boundaries and forms Cr2 N precipitates along the grain boundaries intermittently, which gives rise to the interface ?-Fe/Cr2 N and in?uences strongly both mechanical and electrochemical properties of HNAS. Though the extensive investigations is available concerned with the effect of alloying additives segregation to the grain boundary in HNAS, relying solely on experiments to systematically explore the effects of common alloying additives segregation to the ?-Fe/Cr2 N interfaces from micro-level is highly limiting due to the complexity of the nitride precipitation behavior of the high nitrogen steel. Hence, the adhesion behavior of common alloying additives at interface γ-Fe/Cr2 N is worth to study in HNAS.The structural stability and electronic properties of ε-phase Cr23MN12 were investigated by ?rst-principles calculations. The formation enthalpy and cohesive energy of Cr23MN12(M = Cr, W, Mo, Nb, Fe, Ni) are negative, which indicates that these compounds are thermodynamically stable. Among the doping elements, Nb had the most ease in forming Cr23NbN12, as well as in enhancing its alloying ability. For W and Mo, the formed the phases Cr23WN12 and Cr23MoN12 are more stabilized than pure Cr24N12. For Ni and Fe, the formed the phases Cr23NiN12 and Cr23FeN12 are less stabilized than pure Cr24N12.This study investigated the adhesive behavior of alloying additives M(M = Mn, V, Ti, Mo, Ni) at the ?-Fe(111)/Cr2N(0001) interface as well as the electrochemical effects of these additives in the interface. The results indicated that V and Ti were easily segregated at the ?-Fe(111)/Cr2N(0001) interface and enhanced the adhesive strength. While Ni, Mo, Mn were difficult to segregate at the ?-Fe(111)/Cr2N(0001) interface. Moreover, the results of work function indicated that alloying additives Mn at γ-Fe(111)/Cr2N(0001) interface enhance interfacial corrosion resistance, while alloying additives V, Ni, Ti, Mo at γ-Fe(111)/Cr2N(0001) interface were low-potential sites which usually serve as local attack initiation points.