COMPUTER-SIMULATION OF LEDGE MIGRATION UNDER ELASTIC INTERACTION

The diffusional growth of a phase by the motion of disconnections (led ges which contain transformation or misfit dislocations) was studied b y a finite difference computer model. The elastic stress of these disl ocations is considered to alter the (local equilibrium) solute concent ration at the riser of ledges and cause a complex diffusion field inte raction among ledges as they migrate. In some cases, however, the ledg es forming a train can migrate all at the same speed in the presence o f elastic interaction. The condition under which ledges overcome the e lastic barrier and form a multiple-height ledge was determined. The mo del was applied to the migration of ledges/Shockley partial dislocatio ns at gamma'-plate interfaces in Al-Ag alloys.