scholarly journals Effects of Mo alloying on stability and diffusion of hydrogen in the Nb16H phase: a first-principles investigation

RSC Advances ◽  
2019 ◽  
Vol 9 (34) ◽  
pp. 19495-19500 ◽  
Author(s):  
Dianhui Wang ◽  
Yang Wu ◽  
Zhenzhen Wan ◽  
Feng Wang ◽  
Zhongmin Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Structural Stability ◽  
First Principles ◽  
Hydrogen Diffusion ◽  
First Principles Calculations ◽  
Elastic Band ◽  
Diffusion Behavior ◽  
Band Method ◽  
And Diffusion ◽  
Diffusion Of Hydrogen

First-principles calculations and climbing-image nudged elastic band method were used to investigate the effects of Mo alloying on the structural stability, mechanical properties, and hydrogen-diffusion behavior of Nb.

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.

Barrier to Migration of the Intrinsic Defects in Silicon in Different Charged System Using First-principles Calculations

2005 ◽  
Vol 864 ◽  
Author(s):  
Jinyu Zhang
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Diffusion Behavior ◽  
Generalized Gradient Approximation ◽  
Charged System ◽  
And Diffusion

AbstractUsing density functional theory (DFT) calculations within the generalized gradient approximation (GGA), we have investigated the structure, energies and diffusion behavior of Si defects including interstitial, vacancy, FFCD and divacancy in various charged states.

Effect of Cr doping on the mechanical properties and electronic structure of WCoB ternary boride by first-principles calculations

2018 ◽  
Vol 32 (21) ◽  
pp. 1850240 ◽  
Author(s):  
Tong Zhang ◽  
Haiqing Yin ◽  
Cong Zhang ◽  
Xuanhui Qu ◽  
Qingjun Zheng
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Structural Stability ◽  
First Principles ◽  
Formation Enthalpy ◽  
First Principles Calculations ◽  
Metal Interactions ◽  
Metal Metal ◽  
Ternary Boride ◽  
Cr Doping

The lattice parameters, structural stability, mechanical properties, hardness and electronic structure of WCoB with Cr alloying were investigated by using first-principles calculations. The Cr atom was selected to replace 0, 1, 2, 3, 4 Co atoms in WCoB crystal and 0, 1, 2 Co atoms in W2CoB2 crystal. The calculated cohesive energy and formation enthalpy showed that all structures can retain good structural stability with different Cr doping content. The calculated mechanical properties showed Cr doping will decrease the shear modulus, Young’s modulus, bulk modulus and hardness, but increase the ductility. The larger number of valence electrons of Cr led to the increasing of bond covalence and population. According to the electronic structures analysis, the nonmetal–metal hybridization and metal–metal interactions contributed to relatively high toughness.

scholarly journals Effects of Aluminum on Hydrogen Solubility and Diffusion in Deformed Fe-Mn Alloys

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
C. Hüter ◽  
S. Dang ◽  
X. Zhang ◽  
A. Glensk ◽  
R. Spatschek
Keyword(s):  
Ab Initio ◽  
Equilibrium Model ◽  
Hydrogen Diffusion ◽  
Local Equilibrium ◽  
Minimum Energy ◽  
Trap Site ◽  
Elastic Band ◽  
Band Method ◽  
Minimum Energy Paths ◽  
And Diffusion

We discuss hydrogen diffusion and solubility in aluminum alloyed Fe-Mn alloys. The systems of interest are subjected to tetragonal and isotropic deformations. Based onab initiomodelling, we calculate solution energies and then employ Oriani’s theory which reflects the influence of Al alloying via trap site diffusion. This local equilibrium model is complemented by qualitative considerations of Einstein diffusion. Therefore, we apply the climbing image nudged elastic band method to compute the minimum energy paths and energy barriers for hydrogen diffusion. Both for diffusivity and solubility of hydrogen, we find that the influence of the substitutional Al atom has both local chemical and nonlocal volumetric contributions.

scholarly journals First-principles study of the effect of dopants (Pd, Ni) on the formation and desorption of T2O from a Li2TiO3 (001) surface

RSC Advances ◽  
2019 ◽  
Vol 9 (15) ◽  
pp. 8490-8497 ◽  
Author(s):  
Yiyu Fang ◽  
Xianggang Kong ◽  
You Yu ◽  
Xiaotong Zhang ◽  
Xiaojun Chen ◽  
...  
Keyword(s):  
First Principles ◽  
Tritiated Water ◽  
First Principles Calculations ◽  
Elastic Band ◽  
First Principles Study ◽  
Band Method ◽  
Effect Of Pd

We investigated the effect of Pd and Ni dopants on the formation and desorption of tritiated water (T2O) molecules from the Li2TiO3 (001) surface using first-principles calculations coupled with the climbing-image nudged elastic band method.

scholarly journals Retention and diffusion of transmutation H and He atoms in Be12Ti: first-principles calculations

RSC Advances ◽  
2018 ◽  
Vol 8 (62) ◽  
pp. 35735-35743 ◽  
Author(s):  
Xiaolu Zhu ◽  
Canglong Wang ◽  
Jiajia Liu ◽  
Xingming Zhang ◽  
Huiqiu Deng ◽  
...  
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Diffusion Behavior ◽  
Work First ◽  
And Diffusion ◽  
Insight Into

In this work, first-principles calculations were conducted to gain insight into the retention and diffusion behavior of transmutation H and He atoms in Be12Ti.

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