Comparison of Hydrogen Thermal Desorption Analysis Curves of Electron-Irradiated F82H and Creep-Ruptured Pure Fe Obtained by Experiments and Simulations

2021 ◽  
Vol 1024 ◽  
pp. 135-144
Author(s):  
Takuya Kamimura ◽  
Hayato Yamashita ◽  
Koichi Sato ◽  
Tsunakazu Ohyama ◽  
Yoshinori Kimoto ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Thermal Desorption ◽  
Rate Theory ◽  
Hydrogen Atoms ◽  
Positron Annihilation Lifetime ◽  
Solute Atoms ◽  
Simulation Results ◽  
Diffusion Of Hydrogen ◽  
Trapping Sites ◽  
Thermal Desorption Analysis

Herein, we compared thermal desorption analysis (TDA) curves obtained by conducting experiments and simulations. In addition, we discussed the validation of our simulations and trapping sites of hydrogen atoms. In as-received F82H, when the samples contained solute atoms, grain boundaries, dislocations, and precipitates, the experimental curve corresponded to the simulated curve. In positron annihilation lifetime (PAL) measurements, di-vacancies were detected in the electron-irradiated F82H. When we changed the growth and the concentration of vacancy-type defects during temperature increase using the rate theory, the simulation results agreed with experiment results. In creep-ruptured Fe, only dislocations were detected by the PAL measurements. However, the existence of a type of defect, which was related to grain boundaries, must be assumed to fit the simulation curve to the experimental one. In the next step, the diffusion of hydrogen atoms on grain boundaries should be added to simulation program.

scholarly journals Modeling Thermal Desorption Analysis of Hydrogen in Steel

2006 ◽  
Vol 46 (9) ◽  
pp. 1381-1387 ◽  
Author(s):  
Masato Enomoto ◽  
Daisuke Hirakami ◽  
Toshimi Tarui
Keyword(s):  
Thermal Desorption ◽  
Thermal Desorption Analysis

Inhomogeneous Swelling Near Grain Boundaries in Irradiated Materials: Cavity Nucleation and Growth Saturation Effects

2000 ◽  
Vol 650 ◽  
Author(s):  
S. L. Dudarev
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Nucleation And Growth ◽  
Homogeneous Distribution ◽  
Rate Theory ◽  
Diffusional Growth ◽  
Standard Rate ◽  
Saturation Effects ◽  
Kinetics Of ◽  
Cascade Damage

ABSTRACTThe effect of inhomogeneous nucleation and growth of cavities near grain boundaries illustrates the failure of the standard rate theory to describe the kinetics of phase transformations in irradiated materials under cascade damage conditions. The enhanced swelling observed near grain boundaries is believed to result from the competition between the diffusional growth of cavities and their shrinkage due to the interaction with mobile interstitial clusters. Swelling rates associated with the two processes behave in a radically different way as a function of the size of growing cavities. For a spatially homogeneous distribution of cavities this gives rise to the saturation of swelling in the limit of large irradiation doses.We investigate the evolution of the population of cavities nucleating and growing near a planar grain boundary. We show that a cavity growing near the boundary is able to reach a size that is substantially larger than the size of a cavity growing in the interior region of the grain. For a planar grain boundary the magnitude of swelling at maximum is found to be up to eight times higher than the magnitude of swelling in the grain interior.

MOLECULAR DYNAMICS SIMULATION ON HYDROGEN STORAGE IN METALLIC NANOPARTICLES

2009 ◽  
Vol 08 (01n02) ◽  
pp. 39-42 ◽  
Author(s):  
HIROSHI OGAWA ◽  
AKINORI TEZUKA ◽  
HAO WANG ◽  
TAMIO IKESHOJI ◽  
MASAHIKO KATAGIRI
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Storage ◽  
Metallic Nanoparticles ◽  
Structural Modification ◽  
Structural Features ◽  
Dynamics Simulation ◽  
Metallic Nanoparticle ◽  
Hydrogen Atoms ◽  
Diffusion Of Hydrogen ◽  
Storage Properties

Hydrogen storage in a metallic nanoparticle was simulated by classical molecular dynamics. Distribution of hydrogen atoms inside nanoparticle was investigated by changing length and energy parameters of metal– H bonds. Hydrogen atoms diffused into the particle and distributed homogeneously in case of weak metal– H bonds. In case of strong metal– H bonds, a hydrogen-rich surface layer was observed which suppresses the inward diffusion of hydrogen atoms. Structural modification of nanoparticle accompanied by grain boundary formation due to hydrogen loading was also observed. These variations in dynamical and structural features are considered to affect the hydrogen storage properties in nanoparticles.

scholarly journals Study on the Evolution of the γ′ Phase and Grain Boundaries in Nickel-Based Superalloy during Interrupted Continuous Cooling

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1464
Author(s):  
Haiping Wang ◽  
Dong Liu ◽  
Jianguo Wang ◽  
Yanhui Yang ◽  
Haodong Rao ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Short Distance ◽  
Creep Property ◽  
Maximum Amplitude ◽  
Matrix Diffusion ◽  
Cooling Rates ◽  
Continuous Cooling ◽  
Nickel Based Superalloy ◽  
The Matrix ◽  
Solute Atoms

The formation of the irregular γ′ precipitates in the nickel-based superalloy Waspaloy was investigated during the continuous cooling, which is relevant to the cooling rates and interrupted temperature. The morphology of the γ′ precipitates was observed to change from a dispersed sphere to the flower-like one with the decreasing of the cooling rates. It was found that there are three modes of transportation of the solute atoms involved in relation to the γ′ precipitates: dissolution from the small γ′ precipitates to the γ matrix, diffusion to the large γ′ precipitates from the matrix, and the short distance among γ′ precipitates close to each other. Meanwhile, the slower cooling rates tend to result in the serrated grain boundaries, and the wavelength between successive peaks (λ) and the maximum amplitude (A) are larger with the decreasing of the cooling rates. The content of the low ΣCSL boundaries increases with the decreasing of the cooling rates, which is of great benefit in improving the creep property of the Waspaloy.

Fatigue Crack Propagation Behavior of AZ61 Magnesium Alloy under Controlled Cathodic Potential

2014 ◽  
Vol 891-892 ◽  
pp. 917-922 ◽  
Author(s):  
Tomonori Taniguchi ◽  
Yoshihiko Uematsu ◽  
Yuji Hatano ◽  
Toshifumi Kakiuchi ◽  
Masaki Nakajima ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
Cathodic Potential ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior ◽  
Corrosion Reaction ◽  
Diffusion Of Hydrogen

In the present study, fatigue crack propagation (FCP) tests on Mg alloy, AZ61, were performed in 3% NaCl solution. The cathodic potential was controlled to achieve the hydrogen charged condition without anodic dissolution to figure out the effect of hydrogen on FCP behavior. The cathodic potential was set to be-3.0V, which corresponds to the immunity region without corrosion reaction based on Pourbaix diagram of Mg. The FCP rates were accelerated under hydrogen charged condition compared to those in dry air. Magnesium hydrides, MgH2, were not detected along the crack wake in the measurement by X-ray Diffraction (XRD) method, suggesting that the acceleration could be attributed to the diffusion of hydrogen atoms.

Surface diffusion of hydrogen and CO on Rh(111): Laser‐induced thermal desorption studies

1988 ◽  
Vol 88 (10) ◽  
pp. 6597-6604 ◽  
Author(s):  
E. G. Seebauer ◽  
A. C. F. Kong ◽  
L. D. Schmidt
Keyword(s):  
Surface Diffusion ◽  
Thermal Desorption ◽  
Diffusion Of Hydrogen

Radiation-Induced Minor Element Segregation at Austenitic Stainless Steel Grain Boundaries

1996 ◽  
Vol 439 ◽  
Author(s):  
E. P. Simonen ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundaries ◽  
Neutron Irradiation ◽  
Ion Irradiation ◽  
Austenitic Stainless Steels ◽  
Minor Element ◽  
High Rate ◽  
Rate Theory ◽  
Minor Elements ◽  
Radiation Induced ◽  
Irradiation Behavior

AbstractMeasurement of minor element compositions at irradiated grain boundaries in austenitic stainless steels indicates that Si is the only element that significantly responds to radiation-induced segregation. Other minor elements, such as P or S, do not exhibit elevated grain boundary concentrations after irradiation. A rate theory evaluation of segregation is in accord with ioninduced Si enrichment, but reveals complexities in the interpretation of extrapolating behavior from ion-irradiation to neutron-irradiation behavior. The model calibrated to measured high-rate, ioninduced segregation greatly overestimates measured low-rate, neutron-irradiation segregation of Si.

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