Molecular Dynamics Simulation of the Effect of Hydrogen on the Interaction Between Dislocations in Alpha-Iron

Abstract

In this study, we use extensive molecular dynamics (MD) calculations based on a highly-accurate interatomic potential to examine how hydrogen atoms impact the mechanisms behind the mobilities of edge and screw dislocations in alpha-iron (α-Fe) at a temperature ranging from 300 K to 500 K. The dislocation mobility in α-Fe is shown to be temperature and hydrogen concentration-dependent in this MD investigation. It is demonstrated from the results that hydrogen impurities that are efficient in locking dislocations exist in the form of complexes that are scattered discretely along the dislocation line and that these complexes operate as extremely effective impediments to the mobility of dislocations. The hydrogen impact on the edge dislocation motion from the dislocation velocities versus shear stress reveals that the movement of edge dislocations in α-Fe with hydrogen is much damped as the hydrogen concentration increases. Furthermore, the motion of screw dislocations in the α-Fe is by the process of kink-pair nucleation and migration. according to the simulation results, the locking mechanism of the cross-slip seen along the dislocation path is due to the strong-feature energy landscape and inherent energy fluctuation in the system, resulting in jogs formation.