Effective Hydrogen Diffusion Coefficient and Microstructural Behaviors Measured by Electrochemical Hydrogen Permeation for CoCrFeMnNi High-Entropy Alloy

2019 ◽  
Author(s):  
Junghoon Lee ◽  
Cheolho Park ◽  
Hanji Park ◽  
Namhyun Kang
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Hydrogen Diffusion Coefficient ◽  
Effective Hydrogen

Hydrogen Diffusion Coefficient during Hydrogen Permeation through Nb-Based Hydrogen Permeable Membranes

2009 ◽  
Vol 283-286 ◽  
pp. 225-230 ◽  
Author(s):  
Hiroshi Yukawa ◽  
G.X. Zhang ◽  
N. Watanabe ◽  
Masahiko Morinaga ◽  
T. Nambu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffusion Coefficient ◽  
High Temperature ◽  
Solid Solutions ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient

The hydrogen diffusion coefficients are investigated during the hydrogen permeation through Nb-based hydrogen permeable membranes at high temperature. It is found that the hydrogen diffusion coefficient for pure niobium under practical conditions is much lower than the reported values measured for dilute hydrogen solid solutions. Surprisingly, the hydrogen diffusion is found to be faster in Pd-Ag alloy with fcc crystal structure than in pure niobium with bcc crystal structure at 773K during the hydrogen permeation. It is also found that the addition of Ru or W into niobium increases the hydrogen diffusion coefficient under the practical conditions.

scholarly journals Determining the effective hydrogen diffusion coefficient in 100Cr6

2020 ◽  
Vol 71 (6) ◽  
pp. 918-923
Author(s):  
Dominik Kürten ◽  
Iyas Khader ◽  
Andreas Kailer
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Diffusion Coefficient ◽  
Effective Hydrogen

scholarly journals Hydrogen Diffusivity in Different Microstructures of 42CrMo4 Steel

Hydrogen ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 414-427
Author(s):  
Atif Imdad ◽  
Alfredo Zafra ◽  
Victor Arniella ◽  
Javier Belzunce
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Ferritic Steels ◽  
Hydrogen Diffusivity ◽  
Hydrogen Atoms ◽  
Hydrogen Diffusion Coefficient ◽  
Microstructural Defects ◽  
42Crmo4 Steel

It is well known that the presence of hydrogen decreases the mechanical properties of ferritic steels, giving rise to the phenomenon known as hydrogen embrittlement (HE). The sensitivity to HE increases with the strength of the steel due to the increase of its microstructural defects (hydrogen traps), which eventually increase hydrogen solubility and decrease hydrogen diffusivity in the steel. The aim of this work is to study hydrogen diffusivity in a 42CrMo4 steel submitted to different heat treatments—annealing, normalizing and quench and tempering—to obtain different microstructures, with a broad range of hardness levels. Electrochemical hydrogen permeation tests were performed in a modified Devanathan and Stachursky double-cell. The build-up transient methodology allowed the determination of the apparent hydrogen diffusion coefficient, Dapp, and assessment of its evolution during the progressive filling of the microstructural hydrogen traps. Consequently, the lattice hydrogen diffusion coefficient, DL, was determined. Optical and scanning electron microscopy (SEM) were employed to examine the steel microstructures in order to understand their interaction with hydrogen atoms. In general, the results show that the permeation parameters are strongly related to the steel hardness, being less affected by the type of microstructure.

Analysis of hydrogen diffusion coefficient during hydrogen permeation through niobium and its alloys

2009 ◽  
Vol 476 (1-2) ◽  
pp. 102-106 ◽  
Author(s):  
H. Yukawa ◽  
G.X. Zhang ◽  
N. Watanabe ◽  
M. Morinaga ◽  
T. Nambu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Hydrogen Diffusion Coefficient

scholarly journals Effective hydrogen diffusion coefficient for solidifying aluminium alloys

2011 ◽  
Vol 59 (6) ◽  
pp. 2302-2308 ◽  
Author(s):  
M. Felberbaum ◽  
E. Landry-Désy ◽  
L. Weber ◽  
M. Rappaz
Keyword(s):  
Diffusion Coefficient ◽  
Aluminium Alloys ◽  
Hydrogen Diffusion ◽  
Hydrogen Diffusion Coefficient ◽  
Effective Hydrogen

Alloying Effects on the Hydrogen Diffusivity during Hydrogen Permeation through Nb-Based Hydrogen Permeable Membranes

2010 ◽  
Vol 297-301 ◽  
pp. 1091-1096 ◽  
Author(s):  
Hiroshi Yukawa ◽  
G.X. Zhang ◽  
Masahiko Morinaga ◽  
T. Nambu ◽  
Yoshihisa Matsumoto
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Hydrogen Permeability ◽  
Hydrogen Diffusivity ◽  
Hydrogen Flux ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient ◽  
Alloying Effects

The hydrogen solubility and the hydrogen permeability have been measured for Nb-based alloys in order to investigate the alloying effects on the hydrogen diffusivity during hydrogen permeation. The hydrogen diffusion coefficient during hydrogen permeation is estimated from a linear relationship between the normalized hydrogen flux, , and the difference of hydrogen concentration, C, between the inlet and the outlet sides of the membrane. It is found that the hydrogen diffusion coefficient during the hydrogen permeation is increased by alloying ruthenium or tungsten into niobium. On the other hand, the activation energy for hydrogen diffusion in pure niobium under the practical permeation condition is much higher than the reported values measured for dilute hydrogen solid solutions. It is interesting that the activation energy for hydrogen diffusion decreases by the addition of ruthenium or tungsten into niobium.

Analysis of hydrogen diffusion coefficient during hydrogen permeation through pure niobium

2008 ◽  
Vol 33 (16) ◽  
pp. 4419-4423 ◽  
Author(s):  
G ZHANG ◽  
H YUKAWA ◽  
N WATANABE ◽  
Y SAITO ◽  
H FUKAYA ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Pure Niobium ◽  
Hydrogen Diffusion Coefficient
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