Figure 4. Interfacial velocities of the eutectic colony during solidification.

Measured are the growth rates in the transverse and lateral directions, as indicated by the arrows on the side (90°) silhouette of the colony (see inset). Throughout the growth process, the colony evolves roughly ten times more rapidly in the transverse direction compared to the lateral. The colony extends very slowly in the lateral direction due to the sluggish kinetics of the untwinned {111} lamellae at early times and the bulbs of Al impeding growth at later times. In the transverse direction, the Ge flakes precede the metal and are able to grow unhindered. Error bars represent one s.d., with five measurements.