A first-principle study of the structural, elastic, lattice dynamical and thermodynamic properties of [formula omitted] and [formula omitted] phases

Abstract

Low temperature decomposition of ferrous martensite leads to the formation of alternate C-rich and Fe-rich domains. Although some contradictions exist in the experimental results, the C-rich domains are often supposed to be the ordered α″-Fe16C2 phase. The aim of our theoretical study is to investigate the fundamental properties of the α″-Fe16C2 phase and to compare it to the isomorphic known phase α″-Fe16N2. In this paper, we present the structural, electronic, magnetic, vibrational and elastic properties of α″-Fe16C2 and Fe16N2 phases, calculated within the formalism of the DFT theory. This study is used to discuss the relative properties and stabilities of these two phases.