Static and molecular dynamics simulations have been used with different types of interatomic potentials to investigate the structure, properties and stability of self-interstitial atom (SIA) clusters produced during irradiation. In a-iron (Fe), faulted clusters of <110> dumbbells are unstable for all the potentials. The most stable SIA clusters are sets of parallel <111> crowdions. Large clusters of this type form perfect dislocation loops with Burgers vector b = ½<111>. Small clusters (less th...
Static and molecular dynamics simulations have been used with different types of interatomic potentials to investigate the structure, properties and stability of self-interstitial atom (SIA) clusters produced during irradiation. In a-iron (Fe), faulted clusters of <110> dumbbells are unstable for all the potentials. The most stable SIA clusters are sets of parallel <111> crowdions. Large clusters of this type form perfect dislocation loops with Burgers vector b = ½<111>. Small clusters (less than 9 SIAs) of <100> crowdions are stable at 0K, but transform into a set of <111> crowdions on annealing. Larger <100> clusters are stable and form perfect dislocation loops with b = <100>. Both types of loops are glissile. In copper (Cu), clusters of parallel <100> dumbbells and <110> crowdions are stable. Large clusters of these types form faulted and perfect dislocation loops with b = ¿ <111> and ½ <110> respectively. Small faulted clusters (less than 7 SIAs) of irregular shape can transform into a set of <110> crowdions during annealing. Larger faulted clusters are stable as hexagonal ¿ <111> Frank loops at temperatures of about up to 1050K for a period of several hundred picoseconds. All faulted clusters are sessile. Clusters of <110> crowdions and ½ <110> perfect loops are glissile and stable at all temperatures. When large enough (more than 49–64 SIAs) they can dissociate on their glide prism. Symmetric three-dimensional clusters of <100> dumbbells are stable at 0K but during annealing they transform into sets of <110> crowdions. The results for both iron and copper are discussed and compared with experimental data and provide a basis for investigating and explaining the observed differences in radiation damage accumulation behaviour between fcc and bcc metals.
Grup de recerca
SC-SIMBIO - Sistemes complexos. Simulació discreta de materials i de sistemes biològics
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