Recrystallization is prevented or significantly slowed by a dispersion of small, closely spaced particles due to Zener pinning on both low- and high-angle grain boundaries. This pressure directly opposes the driving force arising from the dislocation density and will influence both the nucleation and growth kinetics. The effect can be rationalized with respect to the particle dispersion level  where  is the volume fraction of the second phase and r is the radius. At low  the grain size is determined by the number of nuclei, and so initially may be very small. However the grains are unstable with respect to grain growth and so will grow during annealing until the particles exert sufficient pinning pressure to halt them. At moderate  the grain size is still determined by the number of nuclei but now the grains are stable with respect to normal growth (while abnormal growth is still possible). At high  the unrecrystallized deformed structure is stable and recrystallization is suppressed.