Computer Simulation of Displacement Cascades in α-Zirconium

1996 ◽  
Vol 439 ◽  
Author(s):  
F. Gao ◽  
S. J. Wooding ◽  
D. J. Bacon ◽  
A. F. Calder ◽  
L. M. Howe
Keyword(s):  
Computer Simulation ◽  
Production Efficiency ◽  
Md Simulations ◽  
Vacancy Cluster ◽  
Prism Plane ◽  
Defect Production ◽  
Displacement Cascades ◽  
Bcc Metals

AbstractThe damage produced in α-zirconium at 100 K by displacement cascades with energy up to 20 keV has been investigated by MD simulations. In agreement with modelling of fcc and bcc metals, the defect production efficiency in zirconium is well below the NRT estimate. The number and size of clusters, both vacancy and interstitial, are increased by increasing PKA energy, and clusters containing up to 25 interstitials and 30 vacancies were formed by 20 keV cascades. Most interstitial clusters have dislocation character with perfect Burgers vectors of the form 1/3<1120>, but a few metastable clusters are formed and are persistent over the timescale of MD simulations. Collapse of the 30-vacancy cluster to a faulted loop on the prism plane was found to occur over a period of more than 100 ps

The Effect of Temperature on Defect Production by Displacement Cascades in alpha;-IRON

1996 ◽  
Vol 439 ◽  
Author(s):  
F. Gao ◽  
D. J. Bacon ◽  
P. E. J. Flewitt ◽  
T. A. Lewis
Keyword(s):  
Molecular Dynamics ◽  
Md Simulations ◽  
Irradiation Temperature ◽  
Effect Of Temperature ◽  
Cascade Process ◽  
Thermal Spike ◽  
Defect Production ◽  
Alpha Iron ◽  
Displacement Cascades ◽  
The Continuum

AbstractMolecular dynamics (MD) simulations have been used to study the number and arrangement of defects produced by displacement cascades as functions of irradiation temperature, Tirr, in α-iron. The continuum treatment of heat conduction was used to adjust the temperature of the MD boundary atoms throughout the cascade process. This new hybrid model has been applied to cascades of either 2 or 5 keV at 100K, 400K, 600K and 900K. The number of Frenkel pairs decreases by about 20–30% as Tir increases from 100K to 900K, due to the increase in the lifetime of the thermal-spike phase. The same effect also brings about an increase in the proportion of selfinterstitial atoms that form clusters.

Computer Simulation of Defect Production and Behaviour in Displacement Cascades in Metals

1998 ◽  
Vol 540 ◽  
Author(s):  
D.J. Bacon ◽  
F. Gao ◽  
A.V. Barashev ◽  
Yu.N. Osetsky
Keyword(s):  
Computer Simulation ◽  
Radiation Damage ◽  
Defect Formation ◽  
Irradiation Temperature ◽  
Cascade Process ◽  
Successful Development ◽  
Defect Production ◽  
Displacement Cascades ◽  
Frenkel Defects ◽  
Atom Energy

AbstractRecent research using molecular dynamics to simulate radiation damage due to displacement cascades in metals is reviewed. It includes results dealing with the effect on defect formation of primary knock-on atom energy and irradiation temperature. Clear dependencies and trends have emerged in these areas. In terms of the development of models to describe the evolution of radiation damage microstructure, the important parameters are not only the total number of Frenkel defects but also the distribution of their population in clusters and the form and mobility of these clusters. Results on these aspects are reviewed and it is shown that computer simulation is providing detailed information that paves the way for successful development of models of the evolution of damage beyond the stage of the cascade process.

Computer Simulation of Energy Dependence of Primary Damage States in SiC

2000 ◽  
Vol 650 ◽  
Author(s):  
R. Devanathan ◽  
F. Gao ◽  
W. J. Weber
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Energy Dependence ◽  
Production Efficiency ◽  
Damage State ◽  
Defect Production ◽  
Highly Dispersed ◽  
Damage States ◽  
Primary Damage

ABSTRACTThe primary damage state in 3C-SiC has been comprehensively studied by molecular dynamics using a modified Tersoff potential. The simulations examined damage produced by Si and C primary knock-on atoms (PKA) with energies from 0.25 to 30 keV. The study also generated statistics of defect production by simulating a number of PKAs at each energy. The defect production efficiency decreases with increasing PKA energy, as observed previously in metals. However, the cascade lifetime is very short (less than 1 ps), localized melting does not occur, the defect arrangements are highly dispersed, and the tendency for defects to form clusters is much less compared to the case of metals. Frenkel pairs on the C sublattice are more numerous than Si Frenkel pairs, and 10-20% of the displacements are in the form of anti-site defects.

Computer Simulation of Defect Production and Behaviour in Displacement Cascades in Metals

1998 ◽  
Vol 538 ◽  
Author(s):  
D.J. Bacon ◽  
F. Gao ◽  
A.V. Barashev ◽  
Yu.N. Osetsky
Keyword(s):  
Computer Simulation ◽  
Radiation Damage ◽  
Defect Formation ◽  
Irradiation Temperature ◽  
Cascade Process ◽  
Successful Development ◽  
Defect Production ◽  
Displacement Cascades ◽  
Frenkel Defects ◽  
Atom Energy

AbstractRecent research using molecular dynamics to simulate radiation damage due to displacement cascades in metals is reviewed. It includes results dealing with the effect on defect formation of primary knock-on atom energy and irradiation temperature. Clear dependencies and trends have emerged in these areas. In terms of the development of models to describe the evolution of radiation damage microstructure, the important parameters are not only the total number of Frenkel defects but also the distribution of their population in clusters and the form and mobility of these clusters. Results on these aspects are reviewed and it is shown that computer simulation is providing detailed information that paves the way for successful development of models of the evolution of damage beyond the stage of the cascade process.

Kinetic Monte Carlo simulations of cascades in Fe alloys

2000 ◽  
Vol 650 ◽  
Author(s):  
C. Domain ◽  
C.S. Becquart ◽  
J.C. van Duysen
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Md Simulations ◽  
Atom Probe ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Displacement Cascades ◽  
Cu Content ◽  
Primary Damage ◽  
Eam Potential

ABSTRACTThe Pressurized Water Reactor vessel steels are embrittled by neutron irradiation. Among the solute atoms, copper play an important role in the embrittlement and different Cu-rich defects have been experimentally observed to form. We have investigated by Kinetic Monte Carlo (KMC) on rigid lattices the evolution of the primary damage. Since the point defects created by the displacement cascades have very different kinetics, their evolution is tracked in two steps. In a first step, we have studied their recombination in the cascade region and the formation of interstitial clusters using “object diffusion”. The parameters of this model are based on MD simulations, or on first principles calculations. In a second part, we have investigated the subsequent evolution of the primary damage with a model based on a vacancy jump mechanism. These simulations which rely on an adapted EAM potential show the formation of copper rich defects. Some of the potential's predictions that played a key role in the model were checked by ab initio calculations. The defects obtained from these simulations, subsequent to the primary damage created by displacement cascades, exhibit similarities with the ones observed by atom probe. The influence of temperature and Cu content on the final damage was investigated.

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