scholarly journals In-situ micro-cantilever bending test in environmental scanning electron microscope: Real time observation of hydrogen enhanced cracking

2017 ◽  
Vol 127 ◽  
pp. 19-23 ◽  
Author(s):  
Y. Deng ◽  
T. Hajilou ◽  
D. Wan ◽  
N. Kheradmand ◽  
A. Barnoush
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Bending Test ◽  
Environmental Scanning ◽  
Time Observation ◽  
Micro Cantilever ◽  
Cantilever Bending ◽  
Real Time Observation ◽  
Scanning Electron

scholarly journals Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope

2017 ◽  
Vol 375 (2098) ◽  
pp. 20170106 ◽  
Author(s):  
Yun Deng ◽  
Tarlan Hajilou ◽  
Afrooz Barnoush
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Ion Beam ◽  
Environmental Scanning Electron Microscope ◽  
Bending Test ◽  
Environmental Scanning ◽  
Micro Cantilever ◽  
Cantilever Bending ◽  
Scanning Electron

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10 −4  Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane. This article is part of the themed issue ‘The challenges of hydrogen and metals’.

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