| Abstract Scope |
Atomistic simulations, using Johnson-Zhou potentials, of the core structure and mobility of ½[111] screw and edge dislocations in complex concentrated BCC alloys are presented. Molecular Dynamics results show that a moving screw dislocation leaves behind interstitial and vacancy dipole debris in these alloys. Solute-dislocation core interaction energies obtained using interatomic potentials are used to determine the critical stress for the motion of screw dislocations as a function of temperature using Rao- Suzuki model of kink migration / kink-kink collisions controlled mobility, developed for concentrated BCC random alloys. In addition, diffusional effects at very high temperatures on the predicted yield behavior are modelled. Edge dislocation mobilities in these alloys are modelled using the Maresca-Curtin model. A simple ductile-brittle transition temperature (DBTT) model for bcc alloys is also presented. The model results on yield/creep, DBTT behavior are shown to be in good agreement with experimental data in selected BCC complex concentrated alloys. |