Effect of Hydrogen on Dislocation Nucleation and Motion: Nanoindentation Experiment and Discrete Dislocation Dynamics Simulation

The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with (110) surface was investigated by both nanoindentation experiments and discrete dislocation dynamics (DDD) simulation. The results of nanoindentation experiments showed that the pop-in load decreased evidently for the electrochemical hydrogen charging specimen, indicating that the dislocation nucleation strength might be reduced by hydrogen. In addition, the decrease of hardness due to hydrogen charging was also captured, implying that the dislocation motion might be promoted by hydrogen. By incorporating the effect of hydrogen on dislocation core energy, a DDD model was specifically proposed to investigate the influence of hydrogen on dislocation nucleation and motion. The results of DDD simulation revealed that under the effect of hydrogen, the dislocation nucleation strength is decreased and the motion of dislocation is promoted.