First-Principles Calculations on Stabilization of Iron Carbides (Fe3C, Fe5C2, and η-Fe2C) in Steels by Common Alloying Elements

The control of carbide formation is crucial for the development of advanced low-alloy steels. Hence, it is of great practical use to know the (de)stabilization of carbides by commonly used alloying elements. Here, we use ab initio density functional theory (DFT) calculations to calculate the stabilization offered by common alloying elements (Al, Si, P, S, Ti, V, Cr, Mn, Ni, Co, Cu, Nb, Mo, and W) to carbides relevant to low-alloy steels, namely cementite \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\hbox{Fe}_{3}\hbox{C}),$$\end{document} Hägg \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\hbox{Fe}_{5}\hbox{C}_{2}),$$\end{document} and eta-carbide \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\eta{\text{-}}\hbox{Fe}_{2}\hbox{C})$$\end{document}. All alloying elements are considered on the Fe sites of the carbides, whereas Al, Si, P, and S are also considered on the C sites. To consider the effect of larger supercell size on the results of (de)stabilization, we use both 1 × 1 × 1 and 2 × 2 × 2 supercells in the case of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox{Fe}_{3}\hbox{C}.$$\end{document}