The impingement effect of an inert, immobile second phase on the recrystallization of a matrix

Two-dimensional computer simulations based on the cellular automaton algorithm were carried out to study the case of the recrystallization of a matrix containing inert, immobile particles. A range of particle area fractions, sizes and aspect ratios were investigated under continuous grain nucleation conditions, assuming that the effect of particles is limited to geometric impingement upon contact with the recrystallizing grains. Particles influence both overall recrystallization kinetics and the geometric characteristics of the recrystallized grain structure. Systematic deviations from the predictions by the Johnson, Mehl, Avrami, Kolmogorov (JMAK) theory for the recrystallization of a particle-free matrix are observed with increasing particle aspect ratio, and, to a lesser extent, particle fraction and size. These deviations are not predicted by a modified JMAK equation assuming that the impingement effect of inert particles is equivalent to that of non-growing grains, and result from the aspect ration and size differences that exist between grains and particles. Inert particles also influence both mean size and mean aspect ratio of the recrystallized grains. While the normalized grain size distributions are unaffected by the particles, the normalized grain aspect ratio distributions exhibit significant variations as the particle geometric parameters are varied.