skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Simulation of defect evolution in irradiated materials: Role of intracascade clustering and correlated recombination

Abstract

The evolution of damage produced by collision cascades in Fe is studied using both kinetic Monte Carlo (kMC) and rate theory (RT) approaches. The initial damage distribution is obtained from molecular-dynamics simulations of 30 keV recoils in Fe. An isochronal annealing is simulated to identify the different thermally activated mechanisms that govern defect evolution. When clusters form during collision cascades, kMC simulations show that additional recovery peaks should be expected, in comparison to recovery curves obtained under electron irradiation conditions. Detailed kMC and RT simulations reveal that some of these recovery peaks are due to correlated recombinations at low temperature between defects. In particular, we show that under cascade-damage conditions it is possible to observe correlated recombinations between vacancies and self-interstitial clusters. These correlated recombinations cannot be reproduced with a RT model, and therefore kMC and RT differ at low temperature. However, for the conditions presented here, the contribution of correlated recombination is very small and therefore no significant differences are observed at high temperatures between these two models.

Authors:
;  [1]
  1. Departamento de Fisica Aplicada, Universidad de Alicante, 03690 San Vicente del Raspeig (Spain)
Publication Date:
OSTI Identifier:
20951408
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 18; Other Information: DOI: 10.1103/PhysRevB.75.184101; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; COLLISIONS; DAMAGE; DEFECTS; ELECTRON BEAMS; INTERSTITIALS; IRON; IRRADIATION; KEV RANGE 10-100; MOLECULAR DYNAMICS METHOD; MONTE CARLO METHOD; RECOMBINATION; SIMULATION; TEMPERATURE RANGE 0065-0273 K; VACANCIES

Citation Formats

Ortiz, C. J., and Caturla, M. J. Simulation of defect evolution in irradiated materials: Role of intracascade clustering and correlated recombination. United States: N. p., 2007. Web. doi:10.1103/PHYSREVB.75.184101.
Ortiz, C. J., & Caturla, M. J. Simulation of defect evolution in irradiated materials: Role of intracascade clustering and correlated recombination. United States. doi:10.1103/PHYSREVB.75.184101.
Ortiz, C. J., and Caturla, M. J. Tue . "Simulation of defect evolution in irradiated materials: Role of intracascade clustering and correlated recombination". United States. doi:10.1103/PHYSREVB.75.184101.
@article{osti_20951408,
title = {Simulation of defect evolution in irradiated materials: Role of intracascade clustering and correlated recombination},
author = {Ortiz, C. J. and Caturla, M. J.},
abstractNote = {The evolution of damage produced by collision cascades in Fe is studied using both kinetic Monte Carlo (kMC) and rate theory (RT) approaches. The initial damage distribution is obtained from molecular-dynamics simulations of 30 keV recoils in Fe. An isochronal annealing is simulated to identify the different thermally activated mechanisms that govern defect evolution. When clusters form during collision cascades, kMC simulations show that additional recovery peaks should be expected, in comparison to recovery curves obtained under electron irradiation conditions. Detailed kMC and RT simulations reveal that some of these recovery peaks are due to correlated recombinations at low temperature between defects. In particular, we show that under cascade-damage conditions it is possible to observe correlated recombinations between vacancies and self-interstitial clusters. These correlated recombinations cannot be reproduced with a RT model, and therefore kMC and RT differ at low temperature. However, for the conditions presented here, the contribution of correlated recombination is very small and therefore no significant differences are observed at high temperatures between these two models.},
doi = {10.1103/PHYSREVB.75.184101},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 18,
volume = 75,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • Understanding materials degradation under intense irradiation is important for the development of next generation nuclear power plants. Here we demonstrate that defect microstructural evolution in molybdenum nanofoils in situ irradiated and observed on a transmission electron microscope can be reproduced with high fidelity using an object kinetic Monte Carlo (OKMC) simulation technique. Main characteristics of defect evolution predicted by OKMC, namely, defect density and size distribution as functions of foil thickness, ion fluence and flux, are in excellent agreement with those obtained from the in situ experiments and from previous continuum-based cluster dynamics modeling. The combination of advanced in situmore » experiments and high performance computer simulation/modeling is a unique tool to validate physical assumptions/mechanisms regarding materials response to irradiation, and to achieve the predictive power for materials stability and safety in nuclear facilities.« less
  • Exposure of metallic structural materials to irradiation environments results in significant microstructural evolution, property changes, and performance degradation, which limits the extended operation of current generation light water reactors and restricts the design of advanced fission and fusion reactors. Further, it is well recognized that these irradiation effects are a classic example of inherently multiscale phenomena and that the mix of radiation-induced features formed and the corresponding property degradation depend on a wide range of material and irradiation variables. This inherently multiscale evolution emphasizes the importance of closely integrating models with high-resolution experimental characterization of the evolving radiation-damaged microstructure. Lastly,more » this article provides a review of recent models of the defect microstructure evolution in irradiated body-centered cubic materials, which provide good agreement with experimental measurements, and presents some outstanding challenges, which will require coordinated high-resolution characterization and modeling to resolve.« less
  • Transmission-electron-microscopy observations are used to evaluate damage produced by irradiating boron-rich metals, semimetals, and semiconductors of three different structure types with energetic electrons. The propensity for damage increases with decreasing carrier concentration except for borides based on twelve-atom icosahedral units. In these semiconducting icosahedral borides neither defect clusters nor amorphorization were observed. In accord with studies of other icosahedral borides, we conclude that radiation-induced boron vacancies and interstitials self-heal in icosahedral borides. We explain this self-healing as having its origin in the unusual structural and electronic stability of fragments of boron-rich icosahedra, termed degraded icosahedra.
  • No abstract prepared.
  • The degree to which ceria can be considered as a surrogate for urania is elucidated by molecular dynamics simulations that compare the types of defect clusters formed under irradiation. The simulations and their comparison with experiments suggest that the defect-clustering processes in the two materials are very similar. In particular, both materials form <1 1 1> Schottky defects and two types of interstitial clusters that, depending on the diffusion conditions, are either charge-neutral dislocation loops or charged cuboctahedral clusters.