Study on the effects of H on the plastic deformation behavior of grain boundaries in Nickle by MD simulation

JW Chen and YX Zhu and MS Huang and L Zhao and S Liang and SL Yuan and ZH Li, MATERIALS & DESIGN, 215, 110472 (2022).

DOI: 10.1016/j.matdes.2022.110472

It is generally believed that the influence of hydrogen on plastic deformation of grain boundaries should be considered when analyzing hydrogen-induced intergranular fracture in polycrystalline metals. In this paper, the equilibrated H distribution around GBs was firstly investigated by employing the grand canon-ical Monte Carlo method. Then, MD simulations were performed to study the plastic response of GBs under uniaxial tensile loads in different directions, with various bulk H concentrations considered. The results indicate that the influence of H on dislocation nucleation from GB depends on both tensile direc-tions and characteristics of GB structures. Specifically, two dislocation nucleation mechanisms, called dis-location dissociation nucleation (DDN) and heterogeneous dislocation nucleation (HDN), are identified. Careful analyses show that H segregation can increase the energy barrier of DDN, which results in H-inhibited dislocation nucleation. In contrast, the HDN mechanism involves H-enhanced or H-insensitive dislocation nucleation, which mainly depends on the influence of H on GB stress. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

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