title: First-principles study of He effects in a bcc Fe grain boundary: site preference, segregation and theoretical tensile strength.
abstract: We perform a first-principles calculation to investigate the effects of He in an Fe Σ5(310)/[001] grain boundary (GB) with the SIESTA code, for which the reliability of the pseudopotential and the basis set are systematically tested. We calculate the formation and segregation energies for different substitutional and interstitial cases in order to determine the site preference and the segregation properties of He in the Fe GB. It is demonstrated that the He segregation either breaks (substitution) or weakens (interstitial) the surrounding interfacial Fe-Fe bonds, leading to the GB tensile strength reduction.
authors.affiliation: Department of Physics, and Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Shu
authors.forename: Shuo
authors.initials: S
authors.lastname: Jin
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Guang-Hong
authors.initials: GH
authors.lastname: Lu
mesh_terms: D006371:Helium / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D006371:Helium; D007501:Iron