  Defects play a key role in deciding the mechanisms and kinetics of phase
transformations. In this paper, we show how dislocations influence phase
separation in alloys with miscibility gap. Specifically, depending on the ratio
of pipe mobility to bulk mobility, it is seen that even in a system with
nominal compositions outside the spinodal limit, spinodal phase separation is
possible. Surprisingly, phase separation through both nucleation and growth,
and spinodal decomposition, is seen concurrently (for the case of intersecting
dislocations). Finally, the prominent role played by dislocations in
influencing the morphology of precipitates is explored. We show that these
results agree qualitatively with recent experimental results in iron based
systems obtained using Atom Probe Tomography (APT).
