Computer simulation of recrystallization-I. Homogeneous nucleation and growth

Abstract

A Monte Carlo computer simulation technique, in which a continuum system is modeled employing a discrete lattice, has been applied to the problem of recrystallization. Primary recrystallization is modeled under conditions where the degree of stored energy is varied and nucleation occurs homogeneously (without regard for position in the microstructure). The nucleation rate is chosen as either constant or site saturated. Temporal evolution of the simulated microstructures is analyzed to provide the time dependence of the recrystallized volume fraction and grain sizes. The recrystallized volume fraction shows sigmoidal variations with time. The data are approximately fit by the Johnson-Mehl-Avrami equation with the expected exponents, however significant deviations are observed for both small and large recrystallized volume fractions. Under site saturated nucleation conditions, the microstructure is initially characterized by the growth of individual recrystallized grains which grow until impingement leaving pockets of unrecrystallized grains and a bimodal grain size distribution. These pockets then recrystallize, often leaving elongated, irregular grains with a relatively homogeneous distribution of grain sizes. When nucleations occurs at a constant rate, the propensity for irregular grain shapes is decreased and the density of two sided grains increases. The final recrystallized grain size (area) is found to be proportional to the nucleation rate to the ( -2 3) power. © 1986.