Formation of secondary defects in copper by 14 MeV neutron irradiation and their effects on microstructure evolution

Observation and analysis of defect cluster production and interactions with dislocations

“…During the early to mid-1980s, Kiritani and coworkers definitively demonstrated the superiority of weak beam electron microscopy for quantitative analysis of small defect clusters produced during neutron irradiation [4,[13][14][15]. Prior to their studies, weak beam microscopy was routinely used by only a few radiation effects researchers [16,17].…”

“…It is worth noting that SFTs are the predominant observed defect cluster geometry ($90% of total visible defect clusters) in ion or neutron irradiated Cu near room temperature for all doses between 10 À5 and 40 dpa [5,14,[23][24][25]34,[38][39][40]. This implies that interstitial-type defects in irradiated Cu, which according to MD simulations are mainly in the form of small glissile clusters, do not efficiently interact with each other to form larger sessile clusters that are visible by TEM.…”

Evolution of Defect Cluster Distributions during Irradiation

“…It has been established experimentally (see, e. g., Black et al [7], Kiritani et al [8]) that vacancies form dislocation loops and stacking fault tetrahedra. Evidence for the formation of interstitial dislocation loops, often in clusters of several loops, during 14 MeV neutron irradiations of copper, e.g., has been presented by Yoshida et al [17]. Molecular dynamics simulations (see, e. g., Guinan and Einney [18], Diaz de la Rubia et al [19]) indicate that vacancies cluster predominantly in the central regions of cascades, whereas interstitials form clusters at the periphery.…”