title: Hydrogen embrittlement in a magnesium grain boundary: a first-principles study.
abstract: First-principles fully relaxed tensile and shear test simulations were performed on Σ10(1124)/[1100] tilt Mg grain boundary (GB) models, with and without H segregation, to investigate mechanisms of H embrittlement of Mg. Strengthening as a result of covalent-like characteristics of Mg-H bonds prevailed over weakening of Mg-Mg bonds resulting from charge transfer; as a result, an H atom strengthened the GB. In addition, because the strong Mg-H bonds suppressed macroscopic GB fracture, elongation to failure was not reduced by H segregation. However, the resistance to GB shearing was increased by H segregation. It is therefore suggested that H segregation enhances crack growth at the GB, because dislocation emission from the crack tip is suppressed, resulting in H embrittlement of Mg.
authors.affiliation: Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Yuasa
authors.forename: Daiki
authors.initials: D
authors.lastname: Nishihara
authors.forename: Mamoru
authors.initials: M
authors.lastname: Mabuchi
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Chino