Segregation and Oxidation Behavior in Be {101̅1} Grain Boundary by First-Principles Calculations

Beryllium has been one promising candidate material for the neutron multiplication in the nuclear fusion reactor. A systematic study has been performed to get insight into the oxidation mechanism in the beryllium {101̅1} grain boundary. It has been found that the diffusion of an O atom from the bulk to grain boundary is much easier than that in the bulk and the grain boundary plane. Furthermore, multiple O atoms may segregate in the grain boundary due to the strong attraction of grain boundary. The O atoms segregated in the grain boundary could interact with the nearby Be atoms with the formation of beryllium oxide, which could be confirmed by the calculation of bond length, charge density difference, and Bader charge. Meanwhile, the pre-existing O atoms could induce the segregation of H atoms. The segregated H atoms could also interact with Be atoms, and beryllium hydride will be formed. The formation of beryllium oxide and beryllium hydride could induce the degradation of strength of Be. The present work could provide a more intensive understanding for the oxidation behavior in the Be grain boundary, which has been experimentally observed when exposed to the extreme environment.