Figure 8.

Phase-field simulation of spherulitic growth from sprinkles. a-d: Time series of the spherulite growth from sprinkles, showing frames 6, 21, 41, 60 of the simulation. a: An early frame in which sprinkles are formed, with random orientation, by nucleation from a solution with high supersaturation. b,c,d: Elongated crystal fibers grow from each sprinkle. Radially oriented crystals continue to elongate, whereas transversally oriented ones abut one another and stop growing. This growth process ultimately results in radially oriented crystals with slight misorientation across grain boundaries, that is, spherulitic growth. Notice that sprinkles nucleate at the liquid-solid interface during GFN. Three white boxes and three black boxes are positioned in identical locations in b, c, d, and are centered around a sprinkle that persists or disappears, respectively. e: Magnified images of the details boxed in b,c,d, panels shown as a function of time in each b,c,d triplet. At the center of the white boxes the sprinkle persists while other sprinkles disappear. In the black boxes at the bottom, almost all sprinkles disappear due to coarsening, which may occur by Ostwald or Smoluchowski ripening, if the system is locally liquid or solid, respectively. Locally slow, incomplete, or gradual solidification enables sprinkle shrinking or rotation.