Molecular dynamics simulation of screw dislocations interacting with interstitial frank loops in a model FCC crystal Original Research Article

Molecular dynamics simulations of screw dislocations interacting with interstitial Frank loops are performed using specific boundary conditions in a model face-centered-cubic nickel crystal, in a configuration favorable to the formation of a helical turn on the dislocation. Both the interaction mechanism and the pinning stress caused by the defects are studied. In particular, we show (1) that the interactions involve athermal cross-slip events, (2) that the shape of the loop has a strong influence: loops with edges along 〈1 1 0〉 directions are unfaulted while loops with 〈1 2 1〉 edges are just sheared and (3) that the Frank loops are strong obstacles with unpinning reactions involving Orowan processes. The consequences of these observations on clear band formation are discussed.