Hydrogen-modified interaction between lattice dislocations and grain boundaries by atomistic modelling

Dislocation plasticity in the vicinity of grain boundaries (GBs) plays a critical role in H- Received 26 September 2019 induced intergranular failure. Their interaction mechanisms under H environment, how- Received in revised form ever, remain largely unexplored. Here, the underlying interaction of a screw dislocation 8 January 2020 with [110] symmetric tilt GBs was studied by using molecular dynamics simulation, with Accepted 16 January 2020 special concerns on the role of solute H in it. Our results show several interaction mech- Available online 13 February 2020 anisms including dislocation dissociation, transmission, nucleation and reflection, depending on different glide planes and GB structures. The presence of H tends to trans- Keywords: form these reactions into ones involving dislocation absorption due to H-hindered GB Dislocation-grain-boundary migration and H-enhanced localised plasticity. Furthermore, it is quantified that solute H interaction leads to an increase in energy barrier for dislocation-grain-boundary interaction. After Molecular dynamics dislocation absorption, the GB segregated with H atoms is activated to a more disordered Corrosion and embrittlement atomic structure, which can be correlated to the crack nucleation and hence the ultimate Fracture mechanisms fracture. These findings advance a mechanistic understanding on H-induced plasticity-mediated intergranular failure. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.