Atomistic Study of Hydrogen Occupation Sites around {112}<111> Edge Dislocation in Alpha Iron
Shinya TAKETOMI, Ryosuke MATSUMOTO and Noriyuki MIYAZAKI
Abstract:Despite the extensive investigations and the recent remarkable progress in experimental equipments, the effects of hydrogen on materials properties have not been sufficiently clarified yet. The difficulties to reveal the essential effects of hydrogen are mainly attributed to the characteristics of hydrogen such as ppm order extremely low concentration and high diffusivity in metals. In this study, we performed molecular statics (MS) analyses of hydrogen occupation sites around a {112}<111> edge dislocation in alpha iron. The stable hydrogen occupation region, where the hydrogen trap energy is strong, is not consistent with the result obtained by continuum theory of elasticity that hydrogen concentrate at the high hydrostatic stress region. According to the MS calculations, hydrogen trap energy has the different characteristics depending on the occupation sites under shear stress as well as hydrostatic stress. Furthermore, this results suggest that the hydrogen concentration on the slip plane around a {112}<111> dislocation can be extremely high. Key Words:Hydrogen embrittlement, Hydrogen diffusion, Molecular dynamics, Edge dislocation, Alpha iron