Origin of micrometer-scale dislocation motion during hydrogen desorption

Motomichi Koyama; Seyedeh Mohadeseh Taheri-Mousavi; Haoxue Yan; Jinwoo Kim; Benjamin Clive Cameron; Seyed Sina Moeini-Ardakani; Ju Li; Cemal Cem Tasan

doi:10.1126/sciadv.aaz1187

Origin of micrometer-scale dislocation motion during hydrogen desorption

Sci Adv. 2020 Jun 5;6(23):eaaz1187. doi: 10.1126/sciadv.aaz1187. eCollection 2020 Jun.

Authors

Motomichi Koyama¹, Seyedeh Mohadeseh Taheri-Mousavi^{2

3}, Haoxue Yan², Jinwoo Kim², Benjamin Clive Cameron⁴, Seyed Sina Moeini-Ardakani⁴, Ju Li^{2

5}, Cemal Cem Tasan²

Affiliations

¹ Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
² Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
³ Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
⁴ Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
⁵ Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.

Abstract

Hydrogen, while being a potential energy solution, creates arguably the most important embrittlement problem in high-strength metals. However, the underlying hydrogen-defect interactions leading to embrittlement are challenging to unravel. Here, we investigate an intriguing hydrogen effect to shed more light on these interactions. By designing an in situ electron channeling contrast imaging experiment of samples under no external stresses, we show that dislocations (atomic-scale line defects) can move distances reaching 1.5 μm during hydrogen desorption. Combining molecular dynamics and grand canonical Monte Carlo simulations, we reveal that grain boundary hydrogen segregation can cause the required long-range resolved shear stresses, as well as short-range atomic stress fluctuations. Thus, such segregation effects should be considered widely in hydrogen research.

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