scholarly journals Correlation factors for interstitial-mediated self-diffusion in the diamond lattice: Kinetic lattice Monte Carlo approach

2011 ◽  
Vol 83 (13) ◽  
Author(s):  
Renyu Chen ◽  
Scott T. Dunham
Keyword(s):  
Monte Carlo ◽  
Diamond Lattice ◽  
Monte Carlo Approach ◽  
Self Diffusion ◽  
Lattice Monte Carlo ◽  
Kinetic Lattice Monte Carlo ◽  
Correlation Factors ◽  
Kinetic Lattice

Kinetic Lattice Monte Carlo Simulations of Cascade Aging in Iron and Dilute Iron-Copper Alloys

1998 ◽  
Vol 540 ◽  
Author(s):  
B. D. Wirth ◽  
G. R. Odette
Keyword(s):  
Monte Carlo ◽  
Copper Alloys ◽  
Defect Cluster ◽  
Thermally Stable ◽  
Cluster Complexes ◽  
Vacancy Clusters ◽  
Lattice Monte Carlo ◽  
Iron Copper ◽  
Kinetic Lattice Monte Carlo ◽  
Kinetic Lattice

AbstractNeutron hardening and embrittlement of pressure vessel steels is due to a high density of nm scale features, including copper-manganese-nickel rich precipitates and what are generally believed to be defect cluster-solute complexes. It has been postulated that the sub nanometer defect cluster-solute complexes form directly in displacement cascades. Cluster-complexes that are thermally unstable mediate the effect of flux on embrittlement kinetics. Larger cluster-complexes, that are relatively thermally stable for irradiation times up to 1 Gs, cause embrittlement in low copper steels. Robust characterization of these two types of so-called matrix defects has been an elusive goal. In this work, Kinetic Lattice Monte Carlo (KLMC) simulations of the long term evolution of the vacancy-rich cascade core regions were carried out for both pure iron and dilute iron-copper alloys at the nominal irradiation temperature of 563°K up to times when the vacancy clusters completely dissolve. Energetics were based on lattice embedded atom method potentials. Special time scaling and pulse annealing techniques were used to deal with the enormous range of inherent time scales involved, viz., rapid free vacancy jumps to slow emission from large complexes. Three-dimensional clusters rapidly form, containing a wide range of vacancies, as well as copper atoms in alloys. Small complexes are very mobile and growth takes place primarily by coalescence. The vacancy clusters ultimately dissolve at times from less than 0.1 to more than 100 MS. These simulations support the hypotheses that cascade cluster- complexes constitute both thermally stable and unstable matrix defect features.

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