Fig. 5: Effects of hydrogen binding configurations (HBCs) on the minimum energy pathway (MEP) of screw dislocation motion without external stress.
From: Hydrogen can both move or pin dislocations in body-centered cubic metals
a MEPs of screw dislocation motion with increasing number of S2 H atoms (see Fig. 4 for binding sites definition) in front of a free dislocation (from zero hydrogen atoms to five hydrogen atoms). Inset shows how the activation barrier changes when the distance between two S2 hydrogen atoms varies. b Representative intermediate images along the MEP for the case of two S2 hydrogen atoms induced dislocation motion (green curve in (a)). c MEPs for locally pinned screw dislocation motion with various number of S2 hydrogen atoms in front of the dislocation line. d Intermediate configurations along the MEP for the case of two S2 hydrogen atoms in (c) (green curve). Hydrogen atoms are in red, while defect Fe atoms are in gray and perfect Fe atoms are not shown.
