DISLOCATION DYNAMICS IN THE 2-D FRENKEL-KONTOROVA MODEL

The Frenkel-Kontorova (FK) model is generalized to two spatial dimensions and studied by finite temperature molecular dynamics simulations. The model allows dislocations of arbitrary orientation and Burgers vector, including edge and screw dislocations. Straight dislocations, dislocation loops and mechanisms for dislocation generation are studied. Two new mechanisms for dislocation generation have been identified: (1) the heterogeneous nucleation of dislocations on pre-existing dislocations and (2) the generation of dislocation loops in the wake of a moving dislocation. These mechanisms may be important in materials subjected to high strain rates.