Direct evaluation of grain boundary hydrogen embrittlement: A micro-mechanical approach

In order to directly investigate the grain boundary (GB) hydrogen embrittlement in polycrystalline materials, a novel micro-mechanical testing method was developed. By combining a site-specific sampling technique and a high-voltage environmental transmission electron microscope (HV ETEM), the fractu...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2016-04, Vol.661, p.211-216
Main Authors: Takahashi, Yoshimasa, Kondo, Hikaru, Asano, Ryo, Arai, Shigeo, Higuchi, Kimitaka, Yamamoto, Yuta, Muto, Shunsuke, Tanaka, Nobuo
Format: Article
Language:English
Subjects:
Fracture
Fracture mechanics
Grain boundaries
Hydrogen embrittlement
Intermetallic compounds
Intermetallics
Micromechanical tests
Nickel aluminides
Nucleation
Plastic deformation
Sampling
TEM
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Summary:In order to directly investigate the grain boundary (GB) hydrogen embrittlement in polycrystalline materials, a novel micro-mechanical testing method was developed. By combining a site-specific sampling technique and a high-voltage environmental transmission electron microscope (HV ETEM), the fracture property of micro-cantilever specimens fabricated from the same GB in a nickel-aluminide (Ni3Al) polycrystal was critically compared in environments with/without hydrogen (H2) gas. For randomly oriented GBs, brittle fracture nucleation accompanied by plastic deformation was observed in a H2-containing environment except for ones with small orientation difference. No GB fracture was observed for coherent Σ3 boundaries. It also appeared that the similitude of the hydrogen-enhanced decohesion (HEDE) mechanism was still valid even for the submicron-scale specimens.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2016.03.035