Repeated grain boundary and grain corner nucleated recrystallization in one- and two-dimensional grain structures

摘要

Repeated recrystallization from grain boundaries and grain boundary corners (triple junctions) in one- and two-dimensional grain structures, respectively, has been investigated by computer simulations. In both the one- and two-dimensional cases it is demonstrated that the grain boundaries/triple junctions after recrystallization from randomly distributed nucleation sites are not completely randomly distributed, and this deviation from randomness is strengthened after several repeated recrystallization transformations. This effects both the kinetics and the resulting size distribution of recrystallized grains. In the one-dimensional case the size distribution sharpens from the initial size distribution of random one-dimensional Voronoi cells, whereas a broadening is obtained in the two-dimensional case. In both cases the Avrami exponent characterizing kinetics is affected and is no longer constant, and in the one-dimensional case it increases as the deviation from randomness increases. However, after a number of repeated transformations a quasi-stationary situation seems to be reached where neither the Avrami exponent nor the size distributions seems to change any further.