scholarly journals The Effect of Stoichiometry on Hydrogen Embrittlement of Ordered Ni3Fe Intermetallics

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Y. X. Chen ◽  
Tao Chen ◽  
Haiyan Qian
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Mechanical Property ◽  
Diffusion Coefficient ◽  
Hydrogen Embrittlement ◽  
Hydrogen Diffusion ◽  
Adsorbed Hydrogen ◽  
Hydrogen Diffusion Coefficient ◽  
Fe Intermetallics ◽  
Degree Of Order

The effects of Fe stoichiometry on hydrogen embrittlement and hydrogen diffusion in ordered Ni3Fe intermetallics were investigated. The experimental results show that the ordered Ni3Fe alloy with the normal stoichiometry has the lowest mechanical property, the highest susceptibility to hydrogen, and the highest ability of catalytic reaction. The mechanical properties, the susceptibility to hydrogen embrittlement, and the amount of adsorbed hydrogen of the ordered Ni3Fe alloy are dependent of degree of order of the alloy. The apparent hydrogen diffusion coefficient of the ordered Ni3Fe alloy is independent on degree of order of the alloy but depends on Fe stoichiometry. The activation energy of hydrogen diffusion decreased linearly with Fe stoichiometry for the ordered Ni3Fe alloy.

Investigation of hydrogen diffusion behavior in 12Cr2Mo1R(H) steel by electrochemical tests and first-principles calculation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiang Qiu ◽  
Kun Zhang ◽  
Qin Kang ◽  
Yicheng Fan ◽  
Hongyu San ◽  
...  
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Hydrogen Atom ◽  
Hydrogen Embrittlement ◽  
First Principles ◽  
Hydrogen Diffusion ◽  
First Principles Calculations ◽  
Content Type ◽  
Diffusion Behavior ◽  
Hydrogen Diffusion Coefficient

Purpose This paper aims to study the mechanism of hydrogen embrittlement in 12Cr2Mo1R(H) steel, which will help to provide valuable information for the subsequent hydrogen embrittlement research of this kind of steel, so as to optimize the processing technology and take more appropriate measures to prevent hydrogen damage. Design/methodology/approach The hydrogen diffusion coefficient of 12Cr2Mo1R(H) steel was measured by the hydrogen permeation technique of double electrolytic cells. Moreover, the influence of hydrogen traps in the material and experimental temperature on hydrogen diffusion behavior was discussed. The first-principles calculations based on density functional theory were used to study the occupancy of H atoms in the bcc-Fe cell, the diffusion path and the interaction with vacancy defects. Findings The results revealed that the logarithm of the hydrogen diffusion coefficient of the material has a linear relationship with the reciprocal of temperature and the activation energy of hydrogen atom diffusion in 12Cr2Mo1R(H) steel is 23.47 kJ/mol. H atoms stably exist in the nearly octahedral interstices in the crystal cell with vacancies. In addition, the solution of Cr/Mo alloy atom does not change the lowest energy path of H atom, but increases the diffusion activation energy of hydrogen atom, thus hindering the diffusion of hydrogen atom. Cr/Mo and vacancy have a synergistic effect on inhibiting the diffusion of H atoms in α-Fe. Originality/value This article combines experiments with first-principles calculations to explore the diffusion behavior of hydrogen in 12Cr2Mo1R(H) steel from the macroscopic and microscopic perspectives, which will help to establish a calculation model with complex defects in the future.

Effect of Degree of Order on Hydrogen Diffusion in (Fe,Ni)3V Alloys

2016 ◽  
Vol 849 ◽  
pp. 475-481
Author(s):  
Ye Xin Chen ◽  
Xi Bei Hou ◽  
Tao Chen
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Diffusion ◽  
Arrhenius Equation ◽  
Time Lag ◽  
Tensile Fracture ◽  
Charging Time ◽  
Hydrogen Diffusion Coefficient ◽  
The Relationship ◽  
Degree Of Order ◽  
Diffusion Behaviors

The effect of hydrogen on the mechanical properties of disordered and ordered (Fe,Ni)3V alloys has been investigated. The diffusion behaviors of hydrogen in the disordered and ordered (Fe,Ni)3V alloys were reported. The results showed that the depth of intergranular (IG) fracture on a surface of tensile fracture of (Fe,Ni)3V alloy increased linearly with increasing pre-charging temperature at the same pre-charging time. An apparent hydrogen diffusion coefficient was calculated by the time lag method. The apparent hydrogen diffusion coefficient in the disordered (Fe,Ni)3V alloy was greater than that in the ordered (Fe,Ni)3V alloy. The relationship between the apparent hydrogen diffusion coefficient and pre-charging temperature in (Fe,Ni)3V alloy agreed with Arrhenius equation. The activation energies of apparent hydrogen diffusion in the disordered and ordered (Fe,Ni)3V alloys were 34.6 kJ/mol and 42.2 kJ/mo1, respectively.

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.

scholarly journals Hydrogen Diffusion Coefficient, Hydrogen Solution Coefficient and Hydrogen Permeability of Nb-TiNi Eutectic Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 1131-1136
Author(s):  
Wei Liang Wang ◽  
Kazuhiro Ishikawa ◽  
Kiyoshi Aoki
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Absorption ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeability ◽  
K Value ◽  
Hydrogen Flow ◽  
Hydrogen Diffusion Coefficient ◽  
High K ◽  
Pressure Region ◽  
The Difference

In general, hydrogen permeabilityΦ of the alloy membrane is expressed as the product of the hydrogen diffusion coefficient D and the hydrogen solution coefficient K. Therefore, to improve the hydrogen permeability efficiently, the values of K and D should be separately considered. In the present study, hydrogen absorption and permeation behaviors of the Nb19Ti40Ni41 alloy consisting of the eutectic phase are investigated by measuring pressure-composition-isotherm (PCI) and by the hydrogen flow method and compared with those of palladium. The hydrogen absorption in the Nb19Ti40Ni41 alloy does not obey the Sieverts’ law in the pressure region of 0-1.0MPa at 523K, but it shows linear relationship between the difference in the square root of hydrogen pressure and hydrogen content between 0.1 and 0.4MPa. Although the value of D for the Nb19Ti40Ni41 alloy is considerably lower than that of palladium, its high K value enhances the hydrogen permeability Φ. It is suggested that the enhancement of D by microstructural control for Nb19Ti40Ni41 alloy is effective for improvement of Φ.

Influence of Phases Stability on the Hydrogen Diffusion Coefficient in Ti-6Al-4V

2020 ◽  
Vol 986 ◽  
pp. 33-40
Author(s):  
Mohammed Kasim Mohsun
Keyword(s):  
Heat Treatment ◽  
Diffusion Coefficient ◽  
Titanium Alloys ◽  
Hydrogen Diffusion ◽  
Volume Fraction ◽  
Substantial Effect ◽  
Diffusion Annealing ◽  
Hydrogen Treatment ◽  
Β Phase ◽  
Hydrogen Diffusion Coefficient

For a unique microstructure creation, thermo-hydrogen treatment (THT), using hydrogen as a temporary alloying element within the heat treatment, is applied. This advanced heat treatment requires reliable data about the hydrogen diffusion coefficient (DH) for understanding diffusion kinetics and its effect on the mechanical behavior of the resulted phases. In this research, three different homogeneous microstructures were established for the investigation using different homogenization parameters. After that, the concentration of hydrogen, charged in the half-length of thin titanium rods via electrochemical hydrogenation, is specified. Then, a diffusion annealing heat treatment was carried out at different temperatures, leading to hydrogen diffusion in the hydrogenated specimens. Furthermore, DH was systematically determined using two methods including the explicit finite difference method (EFDM) and Matano technique (MT). For this purpose, Abaqus software was employed for modeling the hydrogen gradient established in the specimens. Additionally, scanning electron microscopy (SEM) was used for the microstructure examination in order to specify the influence of different hydrogen concentrations on the hydrogenated specimens. The experimental outcomes reveal a substantial effect of the β phase stability and grains sizes of the β and α phases on the hydrogen diffusion. Correspondingly, the results confirm that DH was independent of the hydrogen concentration, and obeys an Arrhenius-type temperature dependence. Furthermore, hydrogen diffusion in the α+β titanium alloys Ti-6Al-4V was slower in comparison to the hydrogen diffusion in the metastable β titanium alloys Ti-10V-2Fe-3Al. In conclusion, it was observed that DH is influenced by the previously performed heat treatments that determine the resulted microstructure types, and a slight influence of the volume fraction of the α phase on DH was observed as well.

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.

Diffusion and Effusion of Hydrogen in Microcrystalline Silicon

1997 ◽  
Vol 467 ◽  
Author(s):  
W. Beyer ◽  
P. Hapke ◽  
U. Zastrow
Keyword(s):  
Diffusion Coefficient ◽  
Infrared Absorption ◽  
Cyclotron Resonance ◽  
Hydrogen Diffusion ◽  
Electron Cyclotron Resonance ◽  
Microcrystalline Silicon ◽  
Hydrogen Diffusion Coefficient ◽  
Internal Surfaces ◽  
Substrate Temperatures ◽  
Hydrogen Effusion

ABSTRACTThe diffusion and effusion of hydrogen in hydrogenated microcrystalline silicon films deposited in an electron cyclotron resonance reactor were studied for various deposition temperatures Ts. For deposition temperatures below 250°C, hydrogen effusion is found to be dominated by desorption of hydrogen from internal surfaces followed by rapid out-diffusion of H2. Higher substrate temperatures result in an increased hydrogen stability suggesting the growth of a more compact material. For this latter type of samples, a hydrogen diffusion coefficient similar as in compact plasma-grown a-Si:H films is found despite a different predominant bonding of hydrogen according to infrared absorption.

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