Elastic constants and structural stability of non-stoichiometric epsilon Ɛ-Fe2.4C carbide

• Published in: Materials chemistry and physics 2019-04, Vol.228, p.210-214
• Main Authors: Salloom, R., Srinivasan, S.G.
• Format: Article
• Language: English
• Subjects: Dynamical stability; Elastic constants; Epsilon carbide; First principles
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2019.02.056

While the elastic properties of cementite are known, there is no corresponding experimental or theoretical data available for the well-known hexagonal Ɛ-Fe2.4C carbide. In this study we investigated the dynamical and mechanical stability of different configurational structures of the hexagonal Ɛ-Fe2.4C carbide. A reliable structural model was established through the ground state energy and phonon calculations, and was used to calculate the elastic constants. The DOS calculations of that structure revealed a strong covalent bonding between Iron and C as shown by low occupation of states at the Fermi level. The calculated mechanical properties (i.e. Young's modulus Y and shear modulus G) of Ɛ-Fe2.4C carbide surpass those of the ubiquitous θ-Fe3C cementite. The calculated elastic properties are predictions, which can be used as an input to establish reliable models for steel development. •A stable configurational model of hexagonal Ɛ-Fe2.4C carbide was identified.•The elastic properties of the hexagonal Ɛ-Fe2.4C carbide were investigated.•The mechanical properties of Ɛ-Fe2.4C carbide surpass those of the cementite.•The DOS of Ɛ-Fe2.4C carbide revealed a strong covalent bonding between atoms.