Effects of interstitial C and N on hydrogen embrittlement behavior of non-equiatomic metastable FeMnCoCr high-entropy alloys

The hydrogen embrittlement behavior of C-doped and C-N co-doped non-equiatomic FeMnCoCr high-entropy alloys were investigated by slow strain rate tensile tests (1 × 10−5 s−1) under in-situ electrochemical hydrogen charging. Multi-scale microstructural analysis suggests that appropriate phase stabili...

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Bibliographic Details
Published in:Corrosion science 2022-01, Vol.194, p.109933, Article 109933
Main Authors: Fu, Zhenghong, Wu, Pengfei, Zhu, Shuya, Gan, Kefu, Yan, Dingshun, Li, Zhiming
Format: Article
Language:English
Subjects:
Alloys
Deformation
Doping
Formability
Grain boundaries
Heat treating
High entropy alloys
Hydrogen
Hydrogen charging
Hydrogen embrittlement
Interstitial high-entropy alloy
Martensite
Martensitic transformation
Microstructural analysis
Phase stability
Planar dislocation slip
Slow strain rate
Stability analysis
Stacking fault energy
Strain analysis
Tensile tests
Twin boundaries
Twinning
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Summary:The hydrogen embrittlement behavior of C-doped and C-N co-doped non-equiatomic FeMnCoCr high-entropy alloys were investigated by slow strain rate tensile tests (1 × 10−5 s−1) under in-situ electrochemical hydrogen charging. Multi-scale microstructural analysis suggests that appropriate phase stability and stacking fault energy adjusted by C-doping provide the alloy with slightly greater resistance to hydrogen embrittlement with the formation of abundant deformation-induced twins and ε-martensite during deformation. The C-N free alloy shows grain boundary and ε/γ interface cracking even though the γ and ε phases have high deformability. C-N co-doping promotes planar dislocation slip, assisting grain- and twin-boundary cracking under deformation in hydrogen. •Hydrogen embrittlement of C-doped and C-N co-doped non-equiatomic FeMnCoCr iHEAs were studied by multi-scale EBSD-ECCI.•Joint activation of deformation twinning and martensitic transformation restrains cracking in C-doped iHEA.•Both of the FCC-γ and HCP-ε phases show high plasticity in hydrogen environment.•Planar-dislocation-slip-induced increase of hydrogen concentration at GBs assists GB cracking in C-N co-doped iHEA.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2021.109933