The structural, magnetic, electronic, and mechanical properties of orthogonal/hexagonal M7C3 (M = Fe and Cr) carbides from first-principles calculations. (September 2022)

• Record Type: Journal Article
• Authors: Zhang, D.; Hou, T.P.; Liang, X.; Zheng, P.; Zheng, Y.H.; Lin, H.F.; Wu, K.M.
• Is Part Of: Vacuum. Volume 203(2022)
• Publication Date: 2022-09
• Subjects: First-principles calculations -- M7C3 carbide -- Electronic structure -- Mechanical properties; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2022.111175
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: First-principles calculations were performed to investigate the structural, magnetic, electronic, and mechanical properties of orthogonal ( o- )/hexagonal ( h- ) M 7 C 3 (M = Fe and Cr) carbides. The o/h-M 7 C 3 structural framework is formed by a 9-vertex Bernal polyhedron (triplet with C-prisms) combined with tetrahedra and octahedra attached to its free triangular faces. The total magnetic properties of the M 7 C 3 carbide arise from the Wyckoff sites of Fe and Cr atom and Fe - (Fe, Cr or C) bond length. M 7 C 3 carbides have the characteristics of covalent, metallic and ionic bonds. Cr substitution causes the reinforcement of the covalent bond of Fe–Cr. Fe 3 Cr 4 C 3 has superior mechanical properties with higher hardness and strength, which indicates the probability of the excellent wear resistance of high chromium cast iron. This investigation provides a theoretical basis for obtaining the excellent physical properties of Fe-based materials. Highlights: M 7 C 3 framework is formed by tetrahedra, octahedra and a 9-vertex Bernal polyhedron. The Wyckoff sites of metal atoms and Fe–C bond length affect the magnetism of M 7 C 3 . The substitution of Cr increases the strength of the Fe–Cr covalent bonds. The Fe 3 Cr 4 C 3 has the priority to the needs of excellent mechanical properties.