Simulation of sub-grain growth during recovery was carried out using two-dimensional discrete dislocation dynamics on a hexagonal crystal lattice having three symmetric slip planes. To account for elevated temperature (i) dislocation climb was allowed and (ii) a Langevin type thermal noise was added to the force acting on the dislocations. During the simulation, a random ensemble of dislocations developed into a sub-grain structure and power-law type growth kinetics were observed. The growth exponent was found to be independent of the climb mobility, but dependent upon the temperature introduced by the thermal noise. The in-depth statistical analysis of the sub-grain structure showed that the coarsening was abnormal, i.e. larger cells grew faster than the small ones, while the average misorientation between the adjacent sub-grains remained nearly constant. During the coarsening Holt's relation was found not to be fulfilled, such that the average sub-grain size was not proportional to the average dislocation spacing. These findings were consistent with recent high precision experiments on recovery.

Abnormal Subgrain Growth in a Dislocation-Based Model of Recovery. P.D.Ispánovity, I.Groma, W.Hoffelner, M.Samaras: Modelling and Simulation in Materials Science and Engineering, 2011, 19[4], 045008