Title

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

RIS ID

141672

Publication Details

Li, J., Lu, C., Pei, L., Zhang, C. & Wang, R. (2020). Hydrogen-modified interaction between lattice dislocations and grain boundaries by atomistic modelling. International Journal of Hydrogen Energy,

Abstract

2020 Hydrogen Energy Publications LLC Dislocation plasticity in the vicinity of grain boundaries (GBs) plays a critical role in H-induced intergranular failure. Their interaction mechanisms under H environment, however, remain largely unexplored. Here, the underlying interaction of a screw dislocation with [11¯0] symmetric tilt GBs was studied by using molecular dynamics simulation, with special concerns on the role of solute H in it. Our results show several interaction mechanisms including dislocation dissociation, transmission, nucleation and reflection, depending on different glide planes and GB structures. The presence of H tends to transform these reactions into ones involving dislocation absorption due to H-hindered GB migration and H-enhanced localised plasticity. Furthermore, it is quantified that solute H leads to an increase in energy barrier for dislocation-grain-boundary interaction. After dislocation absorption, the GB segregated with H atoms is activated to a more disordered atomic structure, which can be correlated to the crack nucleation and hence the ultimate fracture. These findings advance a mechanistic understanding on H-induced plasticity-mediated intergranular failure.

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Link to publisher version (DOI)

http://dx.doi.org/10.1016/j.ijhydene.2020.01.103