scholarly journals The evolution of radiation-induced point defects near symmetrical tilt Σ5 (310) grain boundary in Ga stabilised δ-Pu: A molecular dynamics study

2021 ◽  
pp. 101107
Author(s):  
Yangzhong Wang ◽  
Wenbo Liu ◽  
Jiahui Zhang ◽  
Huan He ◽  
Di Yun ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Point Defects ◽  
Symmetrical Tilt ◽  
Radiation Induced

Atomic Mechanisms of Grain Boundary Motion

2005 ◽  
Vol 502 ◽  
pp. 157-162 ◽  
Author(s):  
A. Suzuki ◽  
Yuri M. Mishin
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Geometric Model ◽  
Lattice Rotation ◽  
Shear Stresses ◽  
Translation Rate ◽  
Embedded Atom ◽  
Local Lattice ◽  
Symmetrical Tilt ◽  
Grain Boundary Motion

We present results of atomistic computer simulations of spontaneous and stress-induced grain boundary (GB) migration in copper. Several symmetrical tilt GBs have been studied using the embedded-atom method and molecular dynamics. The GBs are observed to spontaneously migrate in a random manner. This spontaneous GB motion is always accompanied by relative translations of the grains parallel to the GB plane. Furthermore, external shear stresses applied parallel to the GB and normal to the tilt axis induce GB migration. Strong coupling is observed between the normal GB velocity vn and the grain translation rate v||. The mechanism of GB motion is established to be local lattice rotation within the GB core that does not involve any GB diffusion or sliding. The coupling constant between vn and v|| predicted within a simple geometric model accurately matches the molecular dynamics observations.

Cr-Vacancy Elastic and Chemical Interactions in Irradiated Stainless Steels

1998 ◽  
Vol 540 ◽  
Author(s):  
E. P. Simonen ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Point Defects ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Solution Annealing ◽  
Chemical Interactions ◽  
Radiation Induced ◽  
Solute Interactions ◽  
Present Evaluation ◽  
Nonequilibrium Segregation

AbstractInteractions between point defects and major solute strongly influence grain boundary concentrations during heat treatment, irradiation and annealing of austenitic stainless steels. Previous approaches to nonequilibrium segregation emphasize only elastic defect-solute interactions. The present evaluation of nonequilibrium concentrations at grain boundaries indicates chemical interactions unique to solution annealing and cooling during thermal nonequilibrium segregation (TNES). Subsequent to TNES, radiation-induced segregation and post-irradiation annealing are modeled and compared with measured changes in grain boundary composition. The latter two mechanisms are controlled by exchanges between vacancies and major solute such as Cr.

Modeling of Segregation and Microstructural Evolution near Grain Boundary in FE-CR-NI Alloy Under Irradiation

1998 ◽  
Vol 538 ◽  
Author(s):  
N. Sakaguchi ◽  
S. Watanabe ◽  
H. Takahashi
Keyword(s):  
Activation Energy ◽  
Grain Boundary ◽  
Point Defects ◽  
Solute Segregation ◽  
Extended Defects ◽  
Diffusional Process ◽  
Free Zone ◽  
Ni Alloy ◽  
Radiation Induced ◽  
Simultaneous Evolution

AbstractWe have investigated the solute segregation and simultaneous evolution of extended defects in an Fe-Cr-Ni alloy during irradiation by computer simulation. It sheds a light on the accomplishment of performing “the combined total calculation” or “the muliscale modeling” which deals with both radiation-induced segregation and various kinds of internal sink evolution. The formation of dislocation-free zone (DLFZ) was predicted in the vicinity of a grain boundary. It indicated that DLFZ formation is controlled by solute diffusional process via point defects diffusion near the grain boundary and the activation energy obtained by the width of DLFZ corresponds to the half of the value of the radiation-enhanced solute diffusivity.

Effect of vacancies on the nucleation of Cr precipitates at grain boundary in α-Fe

2019 ◽  
Vol 97 (8) ◽  
pp. 842-846
Author(s):  
Y.Y. Dai ◽  
L. Yang ◽  
J.L. Nie ◽  
S.M. Peng ◽  
X.G. Long ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Model Potential ◽  
Nucleation Mechanism ◽  
Atomic Model ◽  
Long Distance ◽  
Vacancy Clusters ◽  
Vacancy Migration ◽  
Migration Mechanism ◽  
Radiation Induced

Effect of local vacancies on the nucleation of Cr precipitates at Σ3 ⟨110⟩ {112} grain boundary (GB) in α-Fe has been studied using molecular dynamics with a two-band embedded atomic model potential. Radiation-induced vacancies and Cr atoms were directly introduced into the GB core. The local vacancies affect the accumulation of Cr atoms and the evolution of the GB. It is of interest to find that high vacancy concentrations enhance the long-distance migration of Cr, which is mainly correlated to the vacancy migration mechanism, thus leading to the formation of large vacancy-diluted Cr precipitates near the GB plane. Also, the large vacancy clusters are found to be depleted by Cr atoms during relaxation. The accumulation of vacancies and nucleation of Cr precipitates at the GB lead to significant deformation of the GB structure, resulting in the displacement and broadening of the GB. Without vacancies, the GB tends to climb perpendicular to the GB axis. The current research could help in understanding the nucleation mechanism of Cr precipitates at the GB in α-Fe.

scholarly journals Evaluation of Mechanical Properties of Σ5(210)/[001] Tilt Grain Boundary with Self-Interstitial Atoms by Molecular Dynamics Simulation

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Liang Zhang ◽  
Cheng Lu ◽  
Linqing Pei ◽  
Xing Zhao ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Shear Deformation ◽  
Uniaxial Tension ◽  
Dynamics Simulation ◽  
Interstitial Atoms ◽  
Radiation Induced ◽  
Induced Defects

Grain boundary (GB) can serve as an efficient sink for radiation-induced defects, and therefore nanocrystalline materials containing a large fraction of grain boundaries have been shown to have improved radiation resistance compared with their polycrystalline counterparts. However, the mechanical properties of grain boundaries containing radiation-induced defects such as interstitials and vacancies are not well understood. In this study, we carried out molecular dynamics simulations with embedded-atom method (EAM) potential to investigate the interaction of Σ5(210)/[001] symmetric tilt GB in Cu with various amounts of self-interstitial atoms. The mechanical properties of the grain boundary were evaluated using a bicrystal model by applying shear deformation and uniaxial tension. Simulation results showed that GB migration and GB sliding were observed under shear deformation depending on the number of interstitial atoms that segregated on the boundary plane. Under uniaxial tension, the grain boundary became a weak place after absorbing self-interstitial atoms where dislocations and cracks were prone to nucleate.

The damage and healing of quartz under radiation at high temperatures

2019 ◽  
Vol 29 (6) ◽  
pp. 923-942
Author(s):  
Shuai Zhou ◽  
J Woody Ju
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
High Temperatures ◽  
Point Defects ◽  
Potential Application ◽  
Healing Process ◽  
Dynamics Model ◽  
Radiation Induced ◽  
Damage Healing ◽  
Significant Attention

The effect of radiation on silica has attracted significant attention due to its potential application where radiation exists. However, the nature of the atomistic defects of quartz formed during the radiation-induced damage at high temperatures has not been fully elucidated. Molecular dynamics is adopted to investigate the damage-healing behavior of the quartz at high temperatures in this research. The ensuing diffusion and recovery of point defects in the irradiated specimen at high temperatures are simulated. The high temperature reduces the number of point defects. At 1400 K, all point defects are removed, while only some point defects are erased at 700 K. It is illustrated that the over-coordinated atoms are the main source of point defects at 300 K and 700 K. The temperature influences the configuration of point defects. The healing variable of the molecular dynamics model is subsequently developed to describe the healing process. The healing mechanisms of the irradiated specimen at high temperatures are summarized by analyzing the trajectories of atoms in detail. These results are helpful to understand the nature of radiation damage in quartz at high temperatures.

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