title: Parameterized electronic description of carbon cohesion in iron grain boundaries.
abstract: We employ a recently developed iron-carbon orthogonal tight-binding model in calculations of carbon in iron grain boundaries. We use the model to evaluate the properties of carbon near and on the Σ5 (3 1 0)[0 0 1] symmetric tilt grain boundary (GB) in iron, and calculations show that a carbon atom lowers the GB energy by 0.29 eV/atom in accordance with DFT. Carbon segregation to the GB is analyzed, and we find an energy barrier of 0.92 eV for carbon to segregate to the carbon-free interface while segregation to a fully filled interface is disfavored. Local volume (via Voronoi tessellation), magnetic, and electronic effects are correlated with atomic energy changes, and we isolate two different mechanisms governing carbon's behavior in iron: a volumetric strain which increases the energy of carbon in interstitial α iron and a non-strained local bonding which stabilizes carbon at the GB.
authors.affiliation: ICAMS, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hatcher
authors.forename: Georg K H
authors.initials: GK
authors.lastname: Madsen
authors.forename: Ralf
authors.initials: R
authors.lastname: Drautz
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003198:Computer Simulation; D004574:Electromagnetic Fields; D004581:Electronics; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D049329:Nanostructures; D010316:Particle Size; D013499:Surface Properties
chemical_list: D002244:Carbon; D007501:Iron