23 results on '"Hong-Bo Zhou"'
Search Results
2. Influence of helium on the evolution of irradiation-induced defects in tungsten: An object kinetic Monte Carlo simulation*
- Author
-
Xing-Yu Gao, Peng-Wei Hou, Yu-Hao Li, Zhong-Zhu Li, Guang-Hong Lu, Hong-Bo Zhou, Li-Fang Wang, and Haifeng Song
- Subjects
Materials science ,chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Irradiation ,Kinetic Monte Carlo ,Atomic physics ,Tungsten ,Object (computer science) ,Helium - Abstract
Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation. Hereby, we systematically investigate the influence of He on the evolution of Frenkel pairs and collision cascades in tungsten (W) via using the object kinetic Monte Carlo (OKMC) method. Our findings suggest that the presence of He has significant effect on the evolution of irradiation-induced defects. On the one hand, the presence of He can facilitate the recombination of vacancies and self-interstitial atoms (SIAs) in W. This can be attributed to the formation of immobile He-SIA complexes, which increases the annihilation probability of vacancies and SIAs. On the other hand, due to the high stability and low mobility of He-vacancy complexes, the growth of large vacancy clusters in W is kinetically suppressed by He addition. Specially, in comparison with the injection of collision cascades and He in sequential way at 1223 K, the average sizes of surviving vacancy clusters in W via simultaneous way are smaller, which is in good agreement with previous experimental observations. These results advocate that the impurity with low concentration has significant effect on the evolution of irradiation-induced defects in materials, and contributes to our understanding of W performance under irradiation.
- Published
- 2021
3. Characterization of the energetics and configurations of hydrogen in vacancy clusters in tungsten
- Author
-
Yu-Hao Li, Guang-Hong Lu, Qing-Yuan Ren, Zhong-Zhu Li, Long Cheng, and Hong-Bo Zhou
- Subjects
Nuclear and High Energy Physics ,Materials science ,Hydrogen ,Thermal desorption spectroscopy ,Coordination number ,chemistry.chemical_element ,Condensed Matter Physics ,01 natural sciences ,Molecular physics ,010305 fluids & plasmas ,Perfect crystal ,chemistry ,Vacancy defect ,0103 physical sciences ,Cluster (physics) ,Molecule ,Shielding effect ,010306 general physics - Abstract
We have explored the retention of hydrogen (H) in tungsten (W) by investigating its dissolution and aggregation in vacancy clusters (VCs) using a first-principles method and thermodynamic models. The solution energy of a single H in the VCs is in the range of -0.99 ~ -0.64 eV, much lower than that at a mono-vacancy (~ -0.37 eV) and interstitial site (~ 1.01 eV) in W. Such a remarkable discrepancy is rationalized on the electronic interaction of H with its neighboring W atoms, which varies from repulsion to attraction with H moving from perfect crystal to vacancy/VCs. Specifically, the solution/trapping energies of H in VCs can be well categorized by the coordination number of its neighboring W atoms, i.e. the lower the coordination number of W, the stronger is the H-W attraction and the lower is the H solution/trapping energy. Furthermore, taking the V_9^m cluster as an example, it is observed that the multiple H atoms form a multilayer nested cage configuration at VCs surface initially, and then the stable H2 molecules form in the center of VCs. Interestingly, the pre-existed H atoms in VCs inner surface has a shielding effect on the H-W interaction, decreasing the electron density of the central region of VCs and facilitating the formation of H2 molecules. Moreover, the desorption temperatures of H in VCs are also predicted based on the Polanyi-Wigner equation, which are in good agreement with the available thermal desorption spectroscopy experiments. Our calculations provide a good reference to understand the influence of VCs on the retention and evolution of H in W.
- Published
- 2019
4. Towards understanding the influence of Re on H dissolution and retention in W by investigating the interaction between dispersed/aggregated-Re and H
- Author
-
Hong-Bo Zhou, Guang-Hong Lu, Wenwen Wang, Fang-Fei Ma, and Yu-Hao Li
- Subjects
Nuclear and High Energy Physics ,Materials science ,Alloy ,Thermodynamics ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Crystallographic defect ,010305 fluids & plasmas ,0103 physical sciences ,engineering ,0210 nano-technology ,Dissolution - Abstract
We have investigated the effects of Re on the behaviors of H in W as well as their interaction with point defects using a first-principles method in combination with thermodynamic models. It is clearly found that the influence of Re on H is directly related to the distribution of Re in W. For the state of Re dispersed distribution, both a single Re and its complexes with point defects have very slight effect on H dissolution and retention in W. However, the influence of Re clusters (for the state of Re aggregation) on H is extraordinary stronger than that of a single Re. The retention of H in W can be significantly decreased by Re clusters, and their influences will be enhanced with the increasing of the number of Re atoms. This can be attributed to the electronic interaction between H and Re/W, in which the repulsion of Re–H is stronger than that of W–H. We have further examined the retention of H at different temperature in W based on the Polanyi–Wigner equation. It is found that a Re4-vacancy complex can only accommodate 4 H atoms at room temperature, ~33% lower than the maximum number of H atoms in a mono-vacancy. These results give a reasonable interpretation for the experimentally observed D retention significantly decreasing in damaged W–Re alloy in comparison with that in damaged pure W. Consequently, our calculations provide a good reference for evaluating the influence of Re on the performance of W-PFM.
- Published
- 2018
5. Behaviors of transmutation elements Re and Os and their effects on energetics and clustering of vacancy and self-interstitial atoms in W
- Author
-
Huiqiu Deng, Ying Zhang, Shuo Jin, Hong-Bo Zhou, Guang-Hong Lu, and Yu-Hao Li
- Subjects
Nuclear and High Energy Physics ,Materials science ,Binding energy ,Nucleation ,chemistry.chemical_element ,02 engineering and technology ,Activation energy ,Rhenium ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Crystallographic defect ,010305 fluids & plasmas ,chemistry ,Chemical physics ,Vacancy defect ,0103 physical sciences ,Atom ,Osmium ,Atomic physics ,0210 nano-technology - Abstract
We investigate the behaviors of rhenium (Re) and osmium (Os) and their interactions with point defects in tungsten (W) using a first-principles method. We show that Re atoms are energetically favorable to disperse separately in bulk W due to the Re–Re repulsive interaction. Despite the attractive interaction between Os atoms, there is still a large activation energy barrier of 1.10 eV at the critical number of 10 for the formation of Os clusters in bulk W based on the results of the total nucleation free energy change. Interestingly, the presence of vacancy can significantly reduce the total nucleation free energy change of Re/Os clusters, suggesting that vacancy can facilitate the nucleation of Re/Os in W. Re/Os in turn has an effect on the stability of the vacancy clusters (V n ) in W, especially for small vacancy clusters. A single Re/Os atom can raise the total binding energies of V2 and V3 obviously, thus enhancing their formation. Further, we demonstrate that there is a strong attractive interaction between Re/Os and self-interstitial atoms (SIAs). Re/Os could increase the diffusion barrier of SIAs and decrease their rotation barrier, while the interstitial-mediated path may be the optimal diffusion path of Re/Os in W. Consequently, the synergistic effect between Re/Os and point defects plays a key role in Re/Os precipitation and the evolution of defects in irradiated W.
- Published
- 2017
6. Interplay between intrinsic point defects and low-angle grain boundary in bcc tungsten: effects of local stress field
- Author
-
Fei Gao, Xiaolin Shu, Ying Zhang, Guang-Hong Lu, Hong-Bo Zhou, Liang Liang Niu, and Shuo Jin
- Subjects
Materials science ,Condensed matter physics ,chemistry.chemical_element ,Tungsten ,Condensed Matter Physics ,Crystallographic defect ,Stress field ,Crystallography ,Delocalized electron ,chemistry ,Vacancy defect ,Atom ,General Materials Science ,Grain boundary ,Dislocation - Abstract
We have used molecular statics in conjunction with an embedded atom method to explore the interplay between native point defects (vacancies and self-interstitials (SIAs)) and a low-angle grain boundary (GB) in bcc tungsten. The low-angle GB has biased absorption of SIAs over vacancies. We emphasize the significance of phenomena such as vacancy delocalization and SIA instant absorption around the GB dislocation cores in stabilizing the defect structures. Interstitial loading into the GB can dramatically enhance the interaction strength between the point defects and the GB due to SIA clustering (SIA cloud formation) or SIA vacancy recombination. We propose that the 'maximum atom displacement' can complement the 'vacancy formation energy' in evaluating unstable vacancy sites. Calculations of point defect migration barriers in the vicinity of GB dislocation cores show that vacancies and SIAs preferentially migrate along the pathways in the planes immediately above and below the core, respectively.
- Published
- 2015
7. Critical concentration for hydrogen bubble formation in metals
- Author
-
Wenqing Zhang, Guang-Hong Lu, Heun Tae Lee, Hong-Bo Zhou, Shuo Jin, Lu Sun, Yoshio Ueda, and Ying Zhang
- Subjects
Hydrogen ,chemistry ,Transition metal ,Molybdenum ,Refractory metals ,chemistry.chemical_element ,Thermodynamics ,General Materials Science ,Liquid bubble ,Tungsten ,Condensed Matter Physics ,Concentration ratio ,Dimensionless quantity - Abstract
Employing a thermodynamic model with previously calculated first-principle energetics as inputs, we determined the hydrogen (H) concentration at the interstitial and monovacancy as well as its dependence on temperature and pressure in tungsten and molybdenum. Based on this, we predicted the critical H concentration for H bubble formation at different temperatures. The critical concentration, defined as the value when the concentration of H at a certain mH-vacancy complex first became equal to that of H at the interstitial, was 24 ppm/7.3 GPa and 410 ppm/4.7 GPa at 600 K in tungsten and molybdenum in the case of a monovacancy. Beyond the critical H concentration, numerous H atoms accumulated in the monovacancy, leading to the formation and rapid growth of H-vacancy complexes, which was considered the preliminary stage of H bubble formation. We expect that the proposed approach will be generally used to determine the critical H concentration for H bubble formation in metals.
- Published
- 2014
8. A review of modelling and simulation of hydrogen behaviour in tungsten at different scales
- Author
-
Charlotte Becquart, Guang-Hong Lu, and Hong-Bo Zhou
- Subjects
Nuclear and High Energy Physics ,Fusion ,Materials science ,Hydrogen ,Thermodynamics ,chemistry.chemical_element ,Tungsten ,Fusion power ,Condensed Matter Physics ,chemistry ,Thermal ,Liquid bubble ,Diffusion (business) ,Dissolution - Abstract
Tungsten (W) is considered to be one of the most promising plasma-facing materials (PFMs) for next-step fusion energy systems. However, as a PFM, W will be subjected to extremely high fluxes of low-energy hydrogen (H) isotopes, leading to retention of H isotopes and blistering in W, which will degrade the thermal and mechanical properties of W. Modelling and simulation are indispensable to understand the behaviour of H isotopes including dissolution, diffusion, accumulation and bubble formation, which can contribute directly to the design, preparation and application of W as a PFM under a fusion environment. This paper reviews the recent findings regarding the behaviour of H in W obtained via modelling and simulation at different scales.
- Published
- 2014
9. Role of helium in the sliding and mechanical properties of a vanadium grain boundary: A first-principles study
- Author
-
Ying Zhang, Liang-Liang Niu, Xiaolin Shu, Hong-Bo Zhou, and Shuo Jin
- Subjects
Materials science ,chemistry ,General Physics and Astronomy ,Vanadium ,chemistry.chemical_element ,Thermodynamics ,Charge density ,Grain boundary ,Total energy ,Embrittlement ,Helium - Abstract
The effects of helium (He) on the sliding and mechanical properties of a vanadium (V)Σ5(310)/[001] grain boundary (GB) have been investigated using a first-principles method. It has been found that He was energetically favorable sitting at the GB region with a segregation energy of −0.27 eV, which was attributed to the special atomic configurations and charge density distributions of the GB. The maximal sliding energy barrier of the He-doped GB was calculated to be 1.73 J/m2, ~ 35% larger than that of the clean GB. This suggested that the presence of He would hinder the V GB mobility. Based on the thermodynamic criterion, the total energy calculations indicated that the embrittlement of V GB would be enhanced by He segregation.
- Published
- 2014
10. Towards understanding the carbon trapping mechanism in copper by investigating the carbon—vacancy interaction
- Author
-
Hong-Bo Zhou and Shuo Jin
- Subjects
Materials science ,Nucleation ,General Physics and Astronomy ,Charge density ,chemistry.chemical_element ,Trapping ,Activation energy ,Copper ,Metal ,chemistry ,Chemical physics ,Vacancy defect ,visual_art ,Atom ,visual_art.visual_art_medium ,Atomic physics - Abstract
We propose a vacancy trapping mechanism for carbon—vacancy (C—V) complex formation in copper (Cu) according to the first-principles calculations of the energetics and kinetics of C—V interaction. Vacancy reduces charge density in its vicinity to induce C nucleation. A monovacancy is capable of trapping as many as four C atoms to form CnV (n = 1, 2, 3, 4) complexes. A single C atom prefers to interact with neighboring Cu at a vacancy with a trapping energy of −0.21 eV With multiple C atoms added, they are preferred to bind with each other to form covalent-like bonds despite of the metallic Cu environment. For the CnV complexes, C2V is the major one due to its lowest average trapping energy (1.31 eV). Kinetically the formation of the CnV complexes can be ascribed to the vacancy mechanism due to the lower activation energy barrier and the larger diffusion coefficient of vacancy than those of the interstitial C.
- Published
- 2013
11. Stress tensor: A quantitative indicator of effective volume and stability of helium in metals
- Author
-
Feng Liu, Guangquan Lu, Shuo Jin, Yu Zhang, Xiaolin Shu, and Hong-Bo Zhou
- Subjects
Materials science ,Condensed matter physics ,Cauchy stress tensor ,General Physics and Astronomy ,chemistry.chemical_element ,Thermodynamics ,Stress indicator ,Relative stability ,Condensed Matter::Materials Science ,chemistry ,Lattice (order) ,Inert gas ,Effective volume ,Helium - Abstract
We demonstrate a quantitative stress indicator as well as a qualitative hard-sphere lattice model to characterize the effective volume and stability of interstitial helium in fcc and bcc metals, based on extensive first-principles total-energy and lattice stress calculations in combination with continuum elastic theory analyses. The concept of stress indicator is believed to be generally applicable to quantify the relative stability of other inert gas elements in metals.
- Published
- 2011
12. Effects of O in a binary-phase TiAl–Ti3Al alloy: from site occupancy to interfacial energetics
- Author
-
Huibin Xu, Ye Wei, Guang-Hong Lu, Ying Zhang, and Hong-Bo Zhou
- Subjects
Materials science ,Metallurgy ,Alloy ,Energetics ,Thermodynamics ,chemistry.chemical_element ,Cleavage (crystal) ,engineering.material ,Condensed Matter Physics ,Oxygen ,Surface energy ,Octahedron ,chemistry ,Site occupancy ,engineering ,Molecule ,General Materials Science - Abstract
We have investigated site occupancy and interfacial energetics of a TiAl-Ti(3)Al binary-phase system with O using a first-principles method. Oxygen is shown to energetically occupy the Ti-rich octahedral interstitial site, because O prefers to bond with Ti rather than Al. The occupancy tendency of O in TiAl alloy from high to low is α(2)-Ti(3)Al to the γ-α(2) interface and γ-TiAl. We demonstrate that O can largely affect the mechanical properties of the TiAl-Ti(3)Al system. Oxygen at the TiAl-Ti(3)Al interface reduces both the cleavage energy and the interface energy, and thus weakens the interface strength but strongly stabilizes the TiAl/Ti(3)Al interface with the O(2) molecule as a reference. Consequently, the mechanical property variation of TiAl alloy due to the presence of O not only depends on the number of TiAl/Ti(3)Al interfaces but also is related to the O concentration in the alloy.
- Published
- 2011
13. Towards suppressing H blistering by investigating the physical origin of the H–He interaction in W
- Author
-
Shuo Jin, Hong-Bo Zhou, Guang-Hong Lu, Guang-Nan Luo, Ying Zhang, and Yue-Lin Liu
- Subjects
Nuclear and High Energy Physics ,Materials science ,Hydrogen ,Nucleation ,Noble gas ,chemistry.chemical_element ,Charge density ,Condensed Matter Physics ,Crystallographic defect ,chemistry ,Chemical physics ,Vacancy defect ,Redistribution (chemistry) ,Atomic physics ,Helium - Abstract
We investigate the physical origin of H–He interaction in W in terms of optimal charge density by calculating the energetics and diffusion properties using a first-principles method. On the one hand, we show a strong attraction between H and He in W originated from the charge density redistribution due to the presence of He, driving H segregation towards He. This can block the permeation of H into deeper bulk and thus suppress H blistering. On the other hand, we demonstrate that He, rather than H, energetically prefers to occupy the vacancy centre due to its closed-shell structure, which can block H2 formation at the vacancy centre. This is because He causes a redistribution of charge density inside the vacancy to make it ‘not optimal’ for the formation of H2 molecules, which can be treated as a preliminary nucleation of the H bubbles. We thus propose that H retention and blistering in W can be suppressed by doping the noble gas elements.
- Published
- 2010
14. Investigating behaviours of hydrogen in a tungsten grain boundary by first principles: from dissolution and diffusion to a trapping mechanism
- Author
-
Ying Zhang, Guang-Nan Luo, Guang-Hong Lu, Hong-Bo Zhou, Yue-Lin Liu, and Shuo Jin
- Subjects
Nuclear and High Energy Physics ,Materials science ,Diffusion barrier ,Hydrogen ,chemistry.chemical_element ,Charge density ,Condensed Matter Physics ,chemistry ,Chemical physics ,Vacancy defect ,Interstitial defect ,Grain boundary ,Diffusion (business) ,Dissolution - Abstract
We have investigated the dissolution, segregation and diffusion of hydrogen (H) in a tungsten (W) grain boundary (GB) using a first-principles method in order to understand the GB trapping mechanism of H. Optimal charge density plays an essential role in such a GB trapping mechanism. Dissolution and segregation of H are directly associated with the optimal charge density, which can be reflected by the H solution and segregation energy sequence for the different interstitial sites. To occupy the optimal-charge-density site, H can be easily trapped by the W GB with the solution and segregation energy of −0.23 eV and −1.11 eV, respectively. Kinetically, such a trapping is easier to realize due to the much lower diffusion barrier of 0.13–0.16 eV from the bulk to the GB in comparison with the segregation energy, suggesting that it is quite difficult for the trapped H to escape out of the GB. However, the GB can hold no more than 2 H atoms because the isosurface of optimal charge density almost disappears with the second H atom in, leading to the conclusion that H2 molecule and thus H bubble cannot form in the W GB. Taking into account the lower vacancy formation energy in the GB as compared with the bulk, we propose that the experimentally observed H bubble formation in the W GB should be via a vacancy trapping mechanism.
- Published
- 2010
15. First-principles investigation of site preference and bonding properties of alloying element in TiAl with O impurity
- Author
-
Yue-Lin Liu, Ying Zhang, Ye Wei, Guang-Hong Lu, and Hong-Bo Zhou
- Subjects
Local density of states ,Materials science ,Metallurgy ,Condensed Matter Physics ,Preference ,Computer Science Applications ,k-nearest neighbors algorithm ,Crystallography ,Octahedron ,Mechanics of Materials ,Impurity ,Modeling and Simulation ,General Materials Science ,Density functional theory ,Ductility - Abstract
We have investigated site preference and bonding properties of alloying elements including Nb, Mo, Ni and Ag in TiAl with O impurity using a first-principles method based on the density functional theory. We found that the preferable sites for O are the Ti-rich octahedral interstitial ones, while those for the alloying elements are the substitutional ones. Among these elements which are beneficial to improve the mechanical properties of TiAl, Ni and Ag occupy the Al sites, while Nb and Mo occupy the Ti sites. We demonstrate that the presence of O alters the site preference of these alloying elements in TiAl, making these elements prefer to substitute Al that is the first nearest neighbor of O, because O prefers to bond with Ti rather than Al. We suggest that, according to the local density of states results, O can be deleterious to the ductility of TiAl with Nb and Mo, but has little effect on that of TiAl with Ni and Ag.
- Published
- 2009
16. Influence of degenerate four-wave mixing on the performance of supercontinuum-based multiwavelength optical source
- Author
-
Xiao-Fan, Zhao, primary, Yan-Fu, Yang, additional, Hong-Bo, Zhou, additional, Cai-Yun, Lou, additional, and Yi-Zhi, Gao, additional
- Published
- 2007
- Full Text
- View/download PDF
17. Theoretical strength and charge redistribution of fcc Ni in tension and shear
- Author
-
Masanori Kohyama, Guang-Hong Lu, Ying Zhang, Yue-Lin Liu, and Hong-Bo Zhou
- Subjects
Nickel ,Shear (geology) ,Chemical bond ,Condensed matter physics ,Chemistry ,Ultimate tensile strength ,Shear stress ,Charge density ,chemistry.chemical_element ,General Materials Science ,Redistribution (chemistry) ,Total energy ,Condensed Matter Physics - Abstract
We employ a first-principles total-energy method to investigate the theoretical tensile and shear strengths of fcc Ni systematically. The theoretical tensile strengths are shown to be 36.1, 10.5 and 34.1 GPa in the [001], [110] and [111] directions, respectively. We indicate that [110] is the weakest direction due to the formation of an instable bct ‘phase’ in the tensile process. The theoretical shear strengths are, respectively, 5.1 and 15.8 GPa in the ‘easy’ and ‘hard’ directions in the {111}� 112� slip system, and 6.4 GPa in the {111}� 110� slip system. Both the tensile and the shear strengths are consistent with either experimental or theoretical values. The different shear strengths in the ‘easy’ and ‘hard’ directions originate from the different charge redistribution under the shear strain. The shear strain along the ‘easy’ direction of [112] results in a charge distributed in the � 001� which forms a directional bond, while the strain along the ‘hard’ direction of [112] makes the charge extend to the whole {111} interlayers. (Some figures in this article are in colour only in the electronic version)
- Published
- 2008
18. Characterization of the energetics and configurations of hydrogen in vacancy clusters in tungsten.
- Author
-
Qing-Yuan Ren, Yu-Hao Li, Hong-Bo Zhou, Zhong-Zhu Li, L. Cheng, and Guang-Hong Lu
- Subjects
THERMAL desorption ,TUNGSTEN ,VACANCIES in crystals ,WATER clusters ,ELECTRON density ,HYDROGEN ,ATOMS - Abstract
We have explored the retention of hydrogen (H) in tungsten (W) by investigating its dissolution and aggregation in vacancy clusters (VCs) using a first-principles method and thermodynamic models. The solution energy of a single H in the VCs is in the range of −0.99 to −0.64 eV, much lower than that at a mono-vacancy (~ −0.37 eV) and interstitial site (~1.01 eV) in W. Such a remarkable discrepancy is rationalized on the electronic interaction of H with its neighboring W atoms, which varies from repulsion to attraction with H moving from perfect crystal to vacancy/VCs. Specifically, the solution/trapping energies of H in VCs can be well categorized by the coordination number of its neighboring W atoms, i.e. the lower the coordination number of W, the stronger the H–W attraction and the lower the H solution/trapping energy. Furthermore, taking the cluster as an example, it is observed that the multiple H atoms form a multilayer nested cage configuration at the VC surface initially, and then the stable H
2 molecules form in the center of the VCs. Interestingly, the pre-existing H atoms in the VC inner surface have a shielding effect on the H–W interaction, decreasing the electron density of the central region of the VCs and facilitating the formation of H2 molecules. Moreover, the desorption temperatures of H in the VCs are also predicted based on the Polanyi–Wigner equation, and are in good agreement with the available thermal desorption spectroscopy experiments. Our calculations provide a good reference to understand the influence of VCs on the retention and evolution of H in W. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
19. Towards understanding the influence of Re on H dissolution and retention in W by investigating the interaction between dispersed/aggregated-Re and H.
- Author
-
Fang-Fei Ma, Wenwen Wang, Yu-Hao Li, Hong-Bo Zhou, and Guang-Hong Lu
- Subjects
DISSOLUTION (Chemistry) ,THERMODYNAMICS ,RHENIUM ,POINT defects ,TUNGSTEN compounds ,HELIUM ions - Abstract
We have investigated the effects of Re on the behaviors of H in W as well as their interaction with point defects using a first-principles method in combination with thermodynamic models. It is clearly found that the influence of Re on H is directly related to the distribution of Re in W. For the state of Re dispersed distribution, both a single Re and its complexes with point defects have very slight effect on H dissolution and retention in W. However, the influence of Re clusters (for the state of Re aggregation) on H is extraordinary stronger than that of a single Re. The retention of H in W can be significantly decreased by Re clusters, and their influences will be enhanced with the increasing of the number of Re atoms. This can be attributed to the electronic interaction between H and Re/W, in which the repulsion of Re–H is stronger than that of W–H. We have further examined the retention of H at different temperature in W based on the Polanyi–Wigner equation. It is found that a Re
4 -vacancy complex can only accommodate 4 H atoms at room temperature, ~33% lower than the maximum number of H atoms in a mono-vacancy. These results give a reasonable interpretation for the experimentally observed D retention significantly decreasing in damaged W–Re alloy in comparison with that in damaged pure W. Consequently, our calculations provide a good reference for evaluating the influence of Re on the performance of W-PFM. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
20. Behaviors of transmutation elements Re and Os and their effects on energetics and clustering of vacancy and self-interstitial atoms in W.
- Author
-
Yu-Hao Li, Hong-Bo Zhou, Shuo Jin, Ying Zhang, Huiqiu Deng, and Guang-Hong Lu
- Subjects
- *
NUCLEAR reactions , *POINT defects , *TUNGSTEN , *NUCLEATION , *OSMIUM , *RHENIUM - Abstract
We investigate the behaviors of rhenium (Re) and osmium (Os) and their interactions with point defects in tungsten (W) using a first-principles method. We show that Re atoms are energetically favorable to disperse separately in bulk W due to the Re–Re repulsive interaction. Despite the attractive interaction between Os atoms, there is still a large activation energy barrier of 1.10 eV at the critical number of 10 for the formation of Os clusters in bulk W based on the results of the total nucleation free energy change. Interestingly, the presence of vacancy can significantly reduce the total nucleation free energy change of Re/Os clusters, suggesting that vacancy can facilitate the nucleation of Re/Os in W. Re/Os in turn has an effect on the stability of the vacancy clusters (Vn) in W, especially for small vacancy clusters. A single Re/Os atom can raise the total binding energies of V2 and V3 obviously, thus enhancing their formation. Further, we demonstrate that there is a strong attractive interaction between Re/Os and self-interstitial atoms (SIAs). Re/Os could increase the diffusion barrier of SIAs and decrease their rotation barrier, while the interstitial-mediated path may be the optimal diffusion path of Re/Os in W. Consequently, the synergistic effect between Re/Os and point defects plays a key role in Re/Os precipitation and the evolution of defects in irradiated W. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. Interplay between intrinsic point defects and low-angle grain boundary in bcc tungsten: effects of local stress field.
- Author
-
Liang-Liang Niu, Ying Zhang, Xiaolin Shu, Shuo Jin, Hong-Bo Zhou, Fei Gao, and Guang-Hong Lu
- Published
- 2015
- Full Text
- View/download PDF
22. Critical concentration for hydrogen bubble formation in metals.
- Author
-
Lu Sun, Shuo Jin, Hong-Bo Zhou, Ying Zhang, Wenqing Zhang, Y Ueda, H T Lee, and Guang-Hong Lu
- Published
- 2014
- Full Text
- View/download PDF
23. Role of helium in the sliding and mechanical properties of a vanadium grain boundary: A first-principles study.
- Author
-
Hong-Bo Zhou, Shuo Jin, Ying Zhang, Xiao-Lin Shu, and Liang-Liang Niu
- Subjects
- *
HELIUM , *CRYSTAL grain boundaries , *VANADIUM , *NUCLEAR energy , *FUSION reactors , *TOKAMAKS , *THERMONUCLEAR fusion - Abstract
The effects of helium (He) on the sliding and mechanical properties of a vanadium (V)Σ5(310)/[001] grain boundary (GB) have been investigated using a first-principles method. It has been found that He was energetically favorable sitting at the GB region with a segregation energy of −0.27 eV, which was attributed to the special atomic configurations and charge density distributions of the GB. The maximal sliding energy barrier of the He-doped GB was calculated to be 1.73 J/m2, ∼ 35% larger than that of the clean GB. This suggested that the presence of He would hinder the V GB mobility. Based on the thermodynamic criterion, the total energy calculations indicated that the embrittlement of V GB would be enhanced by He segregation. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.